Unilateral physiological FDG uptake in teres minor muscle seems well associated with IV tracer injection procedures.

PubMed

Nakatani, Koya; Nakamoto, Yuji; Togashi, Kaori

2015-01-01

FDG uptake in teres minor (TM) muscle is often physiologically observed. Here we reviewed data of 578 consecutive patients; TM uptake was observed in 138 patients-in 2 of 68 patients who were administered with FDG via a preexisting line and in 136 of 510 after on-site puncture. In 126 patients with TM uptake without unsuccessful on-site puncture, 78% of TM uptake sites were on the ipsilateral side of injection, 8% on the contralateral side, and 14% on both sides; Cohen κ coefficient was 0.815 when confined to unilateral uptake. Therefore, TM uptake seems well associated with tracer injection procedures.

Glucocorticoid interactions with ethanol effects on depolarization-induced calcium influx in brain synaptosomes.

PubMed

Sze, P Y

1996-04-01

Depolarization-induced Ca2+ influx in brain synaptosomes is known to be inhibited by ethanol and stimulated by glucocorticoids. The present study was undertaken to characterize the interactions of corticosterone (CORT) with ethanol effects on 45Ca2+ uptake in synaptosomes depolarized by high K+ (70 mM). CORT was shown to antagonize the inhibitory effects of ethanol on the fast-phase component of the K(+)-induced 45Ca2+ uptake (the initial 3 s following depolarization). Glucocorticoid antagonism of ethanol inhibition of the 45Ca2+ uptake exhibited a high degree of steroid specificity; steroids with glucocorticoid activity including cortisol, dexamethasone and triamcinolone were effective, whereas gonadal steroids and excitatory neuroactive steroid metabolites were ineffective. From the shift of concentration-response relationships when CORT and ethanol were present in combination, the interaction between steroid stimulation and ethanol inhibition of 45Ca2+ uptake occurred in an additive manner over the range of their effective concentrations. Parallel to 45Ca2+ uptake, the binding sites for [3H]PN 200-110 were reduced by ethanol and increased by CORT. These opposite effects on [3H]dihydropyridine labeled sites were found also to antagonize each other, and the antagonism again occurred in an additive relationship. These results demonstrate that glucocorticoids antagonized ethanol inhibition of voltage-dependent Ca2+ channel activity in brain synaptosomes, and support the notion that these steroids may be among the endogenous factors that modulate neuronal sensitivity to ethanol.

Geochemical Influence on Microbial Diversity in the Warm, Salty, Stinking Spring, Utah, USA

NASA Astrophysics Data System (ADS)

Spear, J. R.

2012-12-01

Little is known of the geochemistry and microbiology in the Stinking Springs, a sulfidic, saline, warm spring northeast of the Great Salt Lake, Utah. The International Geobiology Course of 2012 investigated the geochemistry, lipid abundances, dissolved inorganic carbon (DIC) uptake rates and microbial diversity on different kinds of samples from a number of locations in the spring. The measured pH, temperature, salinity, and sulfide concentration along the 100 m flow path ranged from 6.64-7.77, 40-28° C, 2.9-2.2%, and 250 μM - negligible, respectively. Five sites were selected along the flow path and within each site microbial mats were sub-sampled according to their morphological characteristics; a range from floating to streamer-style in zones of higher flow rates to highly-layered mats in low- or sheet-flow zones. Geochemical characterization of the above plus metals, anions and cations were conducted at each site. Genomic DNA was extracted from each microbial sample / layer, and 16S rRNA genes were amplified and subjected to pyrosequencing. Fatty acids and pigments were extracted from the mat samples / layers and analyzed by liquid chromatography and mass spectrometry for lipid / pigment composition. Bicarbonate uptake rates for mat samples / layers were determined with 24 hour light and dark incubations of 13HCO3-spiked spring water. Microbial diversity varied by site and was generally high in all three domains of life with phototrophs, sulfur oxidizers, sulfate reducers, methanogens, and other bacteria / archaea identified by 16S rRNA gene sequence. Diatoms, identified by both microscopy and lipid analyses were found to increase in abundance with distance from the source. Methanogens were generally more abundant in deeper mat laminae and underlying sediments. Photoheterotrophs were found in all mat layers. Microbial diversity increased significantly with depth at most sites. In addition, two distinct microbial streamers were also identified and characterized at the two fast flowing sites. These two streamer varieties were dominated by either cyanobacteria or flavobacteria. Bicarbonate uptake in the light ranged from 0-2.1%/day with maximum rates found in floating, surface mats. Uptake in the dark ranged from 0-0.3%/day and was higher in lower layers. Both 16S rRNA analysis and pigment extractions showed no correlation between high autotrophic rates and presence of cyanobacteria or chlorophyll A. Lipid analysis showed no correlation between bicarbonate uptake and diatom abundance. The results suggest that carbon cycling in the various kinds of mats sampled is dominated by heterotrophs and anaerobic phototrophs despite abundant cyanobacteria and diatoms. A large depletion in sulfate from 16 mM to almost zero combined with low concentrations of measured sulfide and presence of elemental sulfur crystals in most mat samples indicate that the mats are a major sink of S in the system. Overall, our geochemical, genetic, lipid and bicarbonate analysis suggests that the physical and geochemical environment was more predictive of the community composition than mat morphology.

Novel Method to Detect and Characterize 18F-FDG Infiltration at the Injection Site: A Single-Institution Experience.

PubMed

Muzaffar, Razi; Frye, Sarah A; McMunn, Anna; Ryan, Kelley; Lattanze, Ron; Osman, Medhat M

2017-12-01

A novel quality control and quality assurance device provides time-activity curves that can identify and characterize PET/CT radiotracer infiltration at the injection site during the uptake phase. The purpose of this study was to compare rates of infiltration detected by the device with rates detected by physicians. We also assessed the value of using the device to improve injection results in our center. Methods: 109 subjects consented to the study. All had passive device sensors applied to their skin near the injection site and mirrored on the contralateral arm during the entire uptake period. Nuclear medicine physicians reviewed standard images for the presence of dose infiltration. Sensor-generated time-activity curves were independently examined and then compared with the physician reports. Injection data captured by the software were analyzed, and the results were provided to the technologists. Improvement measures were implemented, and rates were remeasured. Results: Physician review of the initial 40 head-to-toe field-of-view images identified 15 cases (38%) of dose infiltration (9 minor, 5 moderate, and 1 significant). Sensor time-activity curves on these 40 cases independently identified 22 cases (55%) of dose infiltration (16 minor, 5 moderate, and 1 significant). After the time-activity curve results and the contributing factor analysis were shared with technologists, injection techniques were modified and an additional 69 cases were studied. Of these, physician review identified 17 cases (25%) of infiltration (13 minor, 3 moderate, and 1 significant), a 34% decline. Sensor time-activity curves identified 4 cases (6%) of infiltration (2 minor and 2 moderate), an 89% decline. Conclusion: The device provides valuable quality control information for each subject. Time-activity curves can further characterize visible infiltration. Even when the injection site was out of the field of view, the time-activity curves could still detect and characterize infiltration. Our initial experience showed that the quality assurance information obtained from the device helped reduce the rate and severity of infiltration. The device revealed site-specific contributing factors that helped nuclear medicine physicians and technologists customize their quality improvement efforts to these site-specific issues. Reducing infiltration can improve image quality and SUV quantification, as well as the ability to minimize variability in a site's PET/CT results. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

Uptake of Workplace HIV Counselling and Testing: A Cluster-Randomised Trial in Zimbabwe

PubMed Central

Corbett, Elizabeth L; Dauya, Ethel; Matambo, Ronnie; Cheung, Yin Bun; Makamure, Beauty; Bassett, Mary T; Chandiwana, Steven; Munyati, Shungu; Mason, Peter R; Butterworth, Anthony E; Godfrey-Faussett, Peter; Hayes, Richard J

2006-01-01

Background HIV counselling and testing is a key component of both HIV care and HIV prevention, but uptake is currently low. We investigated the impact of rapid HIV testing at the workplace on uptake of voluntary counselling and testing (VCT). Methods and Findings The study was a cluster-randomised trial of two VCT strategies, with business occupational health clinics as the unit of randomisation. VCT was directly offered to all employees, followed by 2 y of open access to VCT and basic HIV care. Businesses were randomised to either on-site rapid HIV testing at their occupational clinic (11 businesses) or to vouchers for off-site VCT at a chain of free-standing centres also using rapid tests (11 businesses). Baseline anonymised HIV serology was requested from all employees. HIV prevalence was 19.8% and 18.4%, respectively, at businesses randomised to on-site and off-site VCT. In total, 1,957 of 3,950 employees at clinics randomised to on-site testing had VCT (mean uptake by site 51.1%) compared to 586 of 3,532 employees taking vouchers at clinics randomised to off-site testing (mean uptake by site 19.2%). The risk ratio for on-site VCT compared to voucher uptake was 2.8 (95% confidence interval 1.8 to 3.8) after adjustment for potential confounders. Only 125 employees (mean uptake by site 4.3%) reported using their voucher, so that the true adjusted risk ratio for on-site compared to off-site VCT may have been as high as 12.5 (95% confidence interval 8.2 to 16.8). Conclusions High-impact VCT strategies are urgently needed to maximise HIV prevention and access to care in Africa. VCT at the workplace offers the potential for high uptake when offered on-site and linked to basic HIV care. Convenience and accessibility appear to have critical roles in the acceptability of community-based VCT. PMID:16796402

Target-specific cellular uptake of PLGA nanoparticles coated with poly(L-lysine)-poly(ethylene glycol)-folate conjugate.

PubMed

Kim, Sun Hwa; Jeong, Ji Hoon; Chun, Ki Woo; Park, Tae Gwan

2005-09-13

Poly(D,L-lactic-co-glycolic acid) (PLGA) nanoparticles with anionic surface charge were surface coated with cationic di-block copolymer, poly(L-lysine)-poly(ethylene glycol)-folate (PLL-PEG-FOL) conjugate, for enhancing their site-specific intracellular delivery against folate receptor overexpressing cancer cells. The PLGA nanoparticles coated with the conjugate were characterized in terms of size, surface charge, and change in surface composition by XPS. By employing the flow cytometry method and confocal image analysis, the extent of cellular uptake was comparatively evaluated under various conditions. PLL-PEG-FOL coated PLGA nanoparticles demonstrated far greater extent of cellular uptake to KB cells, suggesting that they were mainly taken up by folate receptor-mediated endocytosis. The enhanced cellular uptake was also observed even in the presence of serum proteins, possibly due to the densely seeded PEG chains. The PLL-PEG-FOL coated PLGA nanoparticles could be potentially applied for cancer cell targeted delivery of various therapeutic agents.

Fatty Acids as Therapeutic Auxiliaries for Oral and Parenteral Formulations

PubMed Central

Hackett, Michael J.; Zaro, Jennica L.; Shen, Wei-Chiang; Guley, Patrick C.; Cho, Moo J.

2012-01-01

Many drugs have decreased therapeutic activity due to issues with absorption, distribution, metabolism and excretion. The co-formulation or covalent attachment of drugs with fatty acids has demonstrated some capacity to overcome these issues by improving intestinal permeability, slowing clearance and binding serum proteins for selective tissue uptake and metabolism. For orally administered drugs, albeit at low level of availability, the presence of fatty acids and triglycerides in the intestinal lumen may promote intestinal uptake of small hydrophilic molecules. Small lipophilic drugs or acylated hydrophilic drugs also show increased lymphatic uptake and enhanced passive diffusional uptake. Fatty acid conjugation of small and large proteins or peptides have exhibited protracted plasma half-lives, site-specific delivery and sustained release upon parenteral administration. These improvements are most likely due to associations with lipid-binding serum proteins, namely albumin, LDL and HDL. These molecular interactions, although not fully characterized, could provide the ability of using the endogenous carrier systems for improving therapeutic outcomes. PMID:22921839

The interplay of contextual elements in implementation: an ethnographic case study.

PubMed

McCullough, Megan B; Chou, Ann F; Solomon, Jeffrey L; Petrakis, Beth Ann; Kim, Bo; Park, Angela M; Benedict, Ashley J; Hamilton, Alison B; Rose, Adam J

2015-02-14

Contextual elements have significant impact on uptake of health care innovations. While existing conceptual frameworks in implementation science suggest contextual elements interact with each other, little research has described how this might look in practice. To bridge this gap, this study identifies the interconnected patterns among contextual elements that influence uptake of an anticoagulation clinic improvement initiative. We completed 51 semi-structured interviews and ethnographic observations across five case study sites involved in an evidence-based practice (EBP) quality improvement initiative. We analyzed data in NVivo 10 using an a priori approach based on the Promoting Action on Research Implementation in Health Services (PARIHS) model and an emergent thematic analysis. Key contextual elements, such as leadership, teamwork, and communication, interacted with each other in contributing to site-level uptake of the EBP, often yielding results that could not be predicted by looking at just one of these elements alone. Sites with context conducive to change in these areas predictably had high uptake, while sites with uniformly weak contextual elements had low uptake. Most sites presented a mixed picture, with contextual elements being strongly supportive of change in some areas and weak or moderate in others. In some cases, we found that sites with strong context in at least one area only needed to have adequate context in other areas to yield high uptake. At other sites, weak context in just one area had the potential to contribute to low uptake, despite countervailing strengths. Even a site with positive views of EBPs could not succeed when context was weak. Interrelationships among different contextual elements can act as barriers to uptake at some sites and as facilitators at others. Accounting for interconnections among elements enables PARIHS to more fully describe the determinants of successful implementation as they operate in real-world settings.

Semiquantitative analysis and characterization of physiological biodistribution of (68)Ga-DOTA-TATE PET/CT.

PubMed

Kunikowska, Jolanta; Królicki, Leszek; Pawlak, Dariusz; Zerizer, Imene; Mikołajczak, Renata

2012-11-01

The aim of this study was to describe the normal physiological distribution of (68)Ga-DOTA-TATE using the SUV to reflect the density of somatostatin receptors in various organ systems. A total of 250 patients (90 men and 160 women) were imaged on a Biograph 64 PET/CT TruePoint (Siemens Medical Solutions) 60 to 80 minutes after injection of 120 to 200 MBq (3.2-5.4 mCi) of (68)Ga-DOTA-TATE. Visual assessment was performed on all studies on the multimodality workstation, and sites of increased uptake were recorded. The SUVmax was also calculated for each organ demonstrating increased (68)Ga-DOTA-TATE uptake. Visual assessment of the (68)Ga-DOTA-TATE PET/CT studies revealed increased uptake in the pituitary, salivary, thyroid glands, liver, spleen, adrenals, kidneys and bone reflecting normal increased somatostatin receptor expression. These sites were confirmed to be disease free on clinical follow-up and on correlation with other imaging (CT/MRI/ultrasound). Using semiquantitative analysis, SUVmax values were the highest in the pituitary gland [11 (4.5)], spleen [18.9 (6.6)], adrenal [14.0 (5.6)], and kidneys [14.2 (3.6)]. In addition, increasing uptake in the uncinate process of pancreas was noted in 12% of patients with SUVmax of 9.2 (3.3). Moderate (68)Ga-DOTA-TATE uptake was also present in salivary gland [3.4 (1.8)], thyroid [2.9 (1.2)], and normal liver [6.5 (2.2)]. The bones generally showed low (68)Ga-DOTA-TATE uptake with an SUVmax of 1.0 (0.3). Knowledge of the normal (68)Ga-DOTA-TATE distribution is highly important for accurate interpretation of this novel imaging modality, which is increasingly being used in the imaging of neuroendocrine tumor.

Improvement of the Uranium Sequestration Ability of a Chlamydomonas sp. (ChlSP Strain) Isolated From Extreme Uranium Mine Tailings Through Selection for Potential Bioremediation Application.

PubMed

Baselga-Cervera, Beatriz; Romero-López, Julia; García-Balboa, Camino; Costas, Eduardo; López-Rodas, Victoria

2018-01-01

The extraction and processing of uranium (U) have polluted large areas worldwide, rendering anthropogenic extreme environments inhospitable to most species. Noticeably, these sites are of great interest for taxonomical and applied bioprospection of extremotolerant species successfully adapted to U tailings contamination. As an example, in this work we have studied a microalgae species that inhabits extreme U tailings ponds at the Saelices mining site (Salamanca, Spain), characterized as acidic (pH between 3 and 4), radioactive (around 4 μSv h -1 ) and contaminated with metals, mainly U (from 25 to 48 mg L -1 ) and zinc (from 17 to 87 mg L -1 ). After isolation of the extremotolerant ChlSP strain, morphological characterization and internal transcribed spacer (ITS)-5.8S gene sequences placed it in the Chlamydomonadaceae , but BLAST analyses identity values, against the nucleotide datasets at the NCBI database, were very low (<92%). We subjected the ChlSP strain to an artificial selection protocol to increase the U uptake and investigated its response to selection. The ancestral strain ChlSP showed a U-uptake capacity of ≈4.30 mg U g -1 of dry biomass (DB). However, the artificially selected strain ChlSG was able to take up a total of ≈6.34 mg U g -1 DB, close to the theoretical maximum response (≈7.9 mg U g -1 DB). The selected ChlSG strain showed two possible U-uptake mechanisms: the greatest proportion by biosorption onto cell walls (ca. 90%), and only a very small quantity, ~0.46 mg g -1 DB, irreversibly bound by bioaccumulation. Additionally, the kinetics of the U-uptake process were characterized during a microalgae growth curve; ChlSG cells removed close to 4 mg L -1 of U in 24 days. These findings open up promising prospects for sustainable management of U tailings waters based on newly evolved extremotolerants and outline the potential of artificial selection in the improvement of desired features in microalgae by experimental adaptation and selection.

Improvement of the Uranium Sequestration Ability of a Chlamydomonas sp. (ChlSP Strain) Isolated From Extreme Uranium Mine Tailings Through Selection for Potential Bioremediation Application

PubMed Central

Baselga-Cervera, Beatriz; Romero-López, Julia; García-Balboa, Camino; Costas, Eduardo; López-Rodas, Victoria

2018-01-01

The extraction and processing of uranium (U) have polluted large areas worldwide, rendering anthropogenic extreme environments inhospitable to most species. Noticeably, these sites are of great interest for taxonomical and applied bioprospection of extremotolerant species successfully adapted to U tailings contamination. As an example, in this work we have studied a microalgae species that inhabits extreme U tailings ponds at the Saelices mining site (Salamanca, Spain), characterized as acidic (pH between 3 and 4), radioactive (around 4 μSv h−1) and contaminated with metals, mainly U (from 25 to 48 mg L−1) and zinc (from 17 to 87 mg L−1). After isolation of the extremotolerant ChlSP strain, morphological characterization and internal transcribed spacer (ITS)-5.8S gene sequences placed it in the Chlamydomonadaceae, but BLAST analyses identity values, against the nucleotide datasets at the NCBI database, were very low (<92%). We subjected the ChlSP strain to an artificial selection protocol to increase the U uptake and investigated its response to selection. The ancestral strain ChlSP showed a U-uptake capacity of ≈4.30 mg U g−1 of dry biomass (DB). However, the artificially selected strain ChlSG was able to take up a total of ≈6.34 mg U g−1 DB, close to the theoretical maximum response (≈7.9 mg U g−1 DB). The selected ChlSG strain showed two possible U-uptake mechanisms: the greatest proportion by biosorption onto cell walls (ca. 90%), and only a very small quantity, ~0.46 mg g−1 DB, irreversibly bound by bioaccumulation. Additionally, the kinetics of the U-uptake process were characterized during a microalgae growth curve; ChlSG cells removed close to 4 mg L−1 of U in 24 days. These findings open up promising prospects for sustainable management of U tailings waters based on newly evolved extremotolerants and outline the potential of artificial selection in the improvement of desired features in microalgae by experimental adaptation and selection. PMID:29662476

Towards real-time topical detection and characterization of FDG dose infiltration prior to PET imaging.

PubMed

Williams, Jason M; Arlinghaus, Lori R; Rani, Sudheer D; Shone, Martha D; Abramson, Vandana G; Pendyala, Praveen; Chakravarthy, A Bapsi; Gorge, William J; Knowland, Joshua G; Lattanze, Ronald K; Perrin, Steven R; Scarantino, Charles W; Townsend, David W; Abramson, Richard G; Yankeelov, Thomas E

2016-12-01

To dynamically detect and characterize 18 F-fluorodeoxyglucose (FDG) dose infiltrations and evaluate their effects on positron emission tomography (PET) standardized uptake values (SUV) at the injection site and in control tissue. Investigational gamma scintillation sensors were topically applied to patients with locally advanced breast cancer scheduled to undergo limited whole-body FDG-PET as part of an ongoing clinical study. Relative to the affected breast, sensors were placed on the contralateral injection arm and ipsilateral control arm during the resting uptake phase prior to each patient's PET scan. Time-activity curves (TACs) from the sensors were integrated at varying intervals (0-10, 0-20, 0-30, 0-40, and 30-40 min) post-FDG and the resulting areas under the curve (AUCs) were compared to SUVs obtained from PET. In cases of infiltration, observed in three sensor recordings (30 %), the injection arm TAC shape varied depending on the extent and severity of infiltration. In two of these cases, TAC characteristics suggested the infiltration was partially resolving prior to image acquisition, although it was still apparent on subsequent PET. Areas under the TAC 0-10 and 0-20 min post-FDG were significantly different in infiltrated versus non-infiltrated cases (Mann-Whitney, p < 0.05). When normalized to control, all TAC integration intervals from the injection arm were significantly correlated with SUV peak and SUV max measured over the infiltration site (Spearman ρ ≥ 0.77, p < 0.05). Receiver operating characteristic (ROC) analyses, testing the ability of the first 10 min of post-FDG sensor data to predict infiltration visibility on the ensuing PET, yielded an area under the ROC curve of 0.92. Topical sensors applied near the injection site provide dynamic information from the time of FDG administration through the uptake period and may be useful in detecting infiltrations regardless of PET image field of view. This dynamic information may also complement the static PET image to better characterize the true extent of infiltrations.

Arsenic (V) bioconcentration kinetics in freshwater macroinvertebrates and periphyton is influenced by pH.

PubMed

Lopez, Adeline R; Funk, David H; Buchwalter, David B

2017-05-01

Arsenic is an important environmental pollutant whose speciation and mobility in freshwater food webs is complex. Few studies have characterized uptake and efflux rates of arsenic in aquatic benthic invertebrates. Further, we lack a fundamental understanding of how pH influences uptake kinetics in these organisms or how this key environmental variable could alter dietary exposure for primary consumers. Here we used a radiotracer approach to characterize arsenate accumulation dynamics in benthic invertebrates, the influence of pH on uptake in a subset of these organisms, and the influence of pH on uptake of arsenate by periphyton - an important food source at the base of aquatic food webs. Uptake rate constants (K u ) from aqueous exposure were modest, ranging from ∼0.001 L g -1 d -1 in three species of mayfly to 0.06 L g -1 d -1 in Psephenus herricki. Efflux rate constants ranged from ∼0.03 d -1 in Corbicula fluminea to ∼0.3 d -1 in the mayfly Isonychia sp, and were generally high. Arsenate uptake decreased with increasing pH, which may be a function of increased adsorption at lower pHs. A similar but much stronger correlation was observed for periphyton where K u decreased from ∼3.0 L g -1 d -1  at 6.5 pH to ∼0.7 L g -1 d -1  at 8.5 pH, suggesting that site specific pH could significantly alter arsenic exposure, particularly for primary consumers. Together, these findings shed light on the complexity of arsenic bioavailability and help explain observed differences reported in the literature. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bacillus subtilis Fur represses one of two paralogous haem-degrading monooxygenases

PubMed Central

Gaballa, Ahmed

2011-01-01

Identification of genes regulated by the ferric uptake regulator (Fur) protein has provided insights into the diverse mechanisms of adaptation to iron limitation. In the soil bacterium Bacillus subtilis, Fur senses iron sufficiency and represses genes that enable iron uptake, including biosynthetic and transport genes for the siderophore bacillibactin and uptake systems for siderophores produced by other organisms. We here demonstrate that Fur regulates hmoA (formerly yetG), which encodes a haem monooxygenase. HmoA is the first characterized member of a divergent group of putative monooxygenases that cluster separately from the well-characterized IsdG family. B. subtilis also encodes an IsdG family protein designated HmoB (formerly YhgC). Unlike hmoA, hmoB is constitutively expressed and not under Fur control. HmoA and HmoB both bind haemin in vitro with approximately 1 : 1 stoichiometry and degrade haemin in the presence of an electron donor. Mutational and spectroscopic analyses indicate that HmoA and HmoB have distinct active site architectures and interact differently with haem. We further show that B. subtilis can use haem as an iron source, but that this ability is independent of HmoA and HmoB. PMID:21873409

Characterization of the Hanford 300 area burial grounds. Task IV. Biological transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fitzner, R.E.; Gano, K.A.; Rickard, W.H.

The characteristics of radioactive waste burial sites at the 300 area burial grounds on the Department of Energy's Hanford Site, southeastern Washington were studied. The potential vectors of radionuclide transport studied were vegetation and animals. The overall results showed a low potential for uptake and transport of radionuclides from the 300 area sites. However, additional methods to control physical and biological mechanisms may contribute to the effectiveness of waste burial practices. From the results, the Biological Transport task recommended field studies which include reduction of soil erosion and addition of biobarriers to plants and animals. Vegetation plays a major rolemore » in reducing soil erosion, and thereby maintaining the backfill over the burial sites. Of the several species found on the 300 area sites, cheatgrass (Bromus tectorum) appears to be the most desirable as a cover. Besides retarding erosion, it has a shallow root system (does not easily penetrate buried material); it has a low affinity for radionuclide uptake; and its tissues are not easily blown away. Small mammals (specifically, mice) appear to have the most potential for radionuclide exposure and uptake. Small mammals were live-trapped within 10 x 10-meter trap grids. Each animal trapped was surgically implanted with a thermoluminescent dosimeter. When the animal was recaptured, the dosimeter was removed and read for exposure. Exposures were reported in milli-Roentgens. The most consistently trapped small mammals were the Great Basin pocket mouse (Perognathus parvus) and the deer mouse (Peromyscus maniculatus). Results from the dosimeter readings showed that some of those animals had higher than background exposures. Biobarriers to animals could be considered as a mechanism to reduce the potential for radionuclide transport.« less

Cloning, expression, and characterization of cadmium and manganese uptake genes from Lactobacillus plantarum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hao, Z.; Chen, S.; Wilson, D.B.

1999-11-01

An Mn{sup 2+} and Cd{sup 2+} uptake gene, mntA, was cloned from Lactobacillus plantarum ATCC 14917 into Escherichia coli. Its expression conferred on E. coli cells increased Cd{sup 2+} sensitivity as well as energy-dependent Cd{sup 2+} uptake activity. Both transcription and translation of mntA were induced by Mn{sup 2+} starvation in L. plantarum, as indicated by reverse transcriptase PCR and immunoblotting. Two Cd{sup 2+} uptake systems have been identified in L. plantarum: one is a high-affinity Mn{sup 2+} and Cd{sup 2+} uptake system that is expressed in Mn{sup 2+}-starved cells, and the other is a nonsaturable Cd{sup 2+} uptake systemmore » that is expressed in Cd{sup 2+}-sufficient cells. MntA was not detected in an Mn{sup 2+}-dependent mutant of L. plantarum which had lost high-affinity Mn{sup 2+} and Cd{sup 2+} uptake activity. The results suggest that mntA is the gene encoding the high-affinity Mn{sup 2+} and Cd{sup 2+} transporter. On the basis of its predicted amino acid sequence, MntA belongs to the family of P-type cation-translocating ATPases. The topology and potential Mn{sup 2+}- and Cd{sup 2+}-binding sites of MntA are discussed. A second clone containing a low-affinity Cd{sup 2+} transport system was also isolated.« less

The K+/site and H+/site stoichiometry of mitochondrial electron transport.

PubMed

Reynafarje, B; Lehninger, A L

1978-09-25

Electrode measurements of the average number of H+ ejected and K+ taken up (in the presence of valinomycin) per pair of electrons passing the energy-conserving sites of the respiratory chain of rat liver and rat heart mitochondria have given identical values of the H+/site and 5+/site ratios very close to 4 in the presence of N-ethylmaleimide, an inhibitor of interfering respiration-coupled uptake of H+ + H2PO4-. The K+/site uptake ratio of 4 not only shows that inward movement of K+ provides quantitative charge-compensation for the 4 H+ ejected, but also confirms that 4 charges are separated per pair of electrons per site. When N-ethylmaleimide is omitted, the H+/site ejection ratio is depressed, because of the interfering secondary uptake of H/+ with H2PO4- on the phosphate carrier, but the K+/site uptake ratio remains at 4.0. Addition of phosphate or acetate, which can carry H+ into respiring mitochondria, further depresses the H+/site ratio, but does not affect the K+/site ratio, which remains at 4.0. These and other considerations thus confirm our earlier stoichiometric measurements that the average H+/site ratio is 4.0 and also show that the K+/site uptake ratio can be used as a measure of the intrinsic H+/site ratio, regardless of the presence of phosphate in the medium and without the necessity of adding N-ethylmaleimide or other inhibitors of H+ + H2PO4- transport.

Root Water Uptake and Soil Moisture Pattern Dynamics - Capturing Connections, Controls and Causalities

NASA Astrophysics Data System (ADS)

Blume, T.; Heidbuechel, I.; Hassler, S. K.; Simard, S.; Guntner, A.; Stewart, R. D.; Weiler, M.

2015-12-01

We hypothesize that there is a shift in controls on landscape scale soil moisture patterns when plants become active during the growing season. Especially during the summer soil moisture patterns are not only controlled by soils, topography and related abiotic site characteristics but also by root water uptake. Root water uptake influences soil moisture patterns both in the lateral and vertical direction. Plant water uptake from different soil depths is estimated based on diurnal fluctuations in soil moisture content and was investigated with a unique setup of 46 field sites in Luxemburg and 15 field sites in Germany. These sites cover a range of geologies, soils, topographic positions and types of vegetation. Vegetation types include pasture, pine forest (young and old) and different deciduous forest stands. Available data at all sites includes information at high temporal resolution from 3-5 soil moisture and soil temperature profiles, matrix potential, piezometers and sapflow sensors as well as standard climate data. At sites with access to a stream, discharge or water level is also recorded. The analysis of soil moisture patterns over time indicates a shift in regime depending on season. Depth profiles of root water uptake show strong differences between different forest stands, with maximum depths ranging between 50 and 200 cm. Temporal dynamics of signal strength within the profile furthermore suggest a locally shifting spatial distribution of root water uptake depending on water availability. We will investigate temporal thresholds (under which conditions spatial patterns of root water uptake become most distinct) as well as landscape controls on soil moisture and root water uptake dynamics.

Carbon exchange between the atmosphere and subtropical forested cypress and pine wetlands

USGS Publications Warehouse

Shoemaker, W. Barclay; Anderson, Frank E.; Barr, Jordan G.; Graham, Scott L.; Botkin, Daniel B.

2015-01-01

Carbon dioxide exchange between the atmosphere and forested subtropical wetlands is largely unknown. Here we report a first step in characterizing this atmospheric–ecosystem carbon (C) exchange, for cypress strands and pine forests in the Greater Everglades of Florida as measured with eddy covariance methods at three locations (Cypress Swamp, Dwarf Cypress and Pine Upland) for 2 years. Links between water and C cycles are also examined at these three sites, as are methane emission measured only at the Dwarf Cypress site. Each forested wetland showed net C uptake from the atmosphere both monthly and annually, as indicated by the net ecosystem exchange (NEE) of carbon dioxide (CO2). For this study, NEE is the difference between photosynthesis and respiration, with negative values representing uptake from the atmosphere that is retained in the ecosystem or transported laterally via overland flow (unmeasured for this study). Atmospheric C uptake (NEE) was greatest at the Cypress Swampp (−900 to −1000 g C m2 yr−1), moderate at the Pine Upland (−650 to −700 g C m2 yr−1) and least at the Dwarf Cypress (−400 to −450 g C m2 yr−1). Changes in NEE were clearly a function of seasonality in solar insolation, air temperature and flooding, which suppressed heterotrophic soil respiration. We also note that changes in the satellite-derived enhanced vegetation index (EVI) served as a useful surrogate for changes in NEE at these forested wetland sites.

Usefulness and pitfalls of MAA SPECT/CT in identifying digestive extrahepatic uptake when planning liver radioembolization.

PubMed

Lenoir, Laurence; Edeline, Julien; Rolland, Yann; Pracht, Marc; Raoul, Jean-Luc; Ardisson, Valérie; Bourguet, Patrick; Clément, Bruno; Boucher, Eveline; Garin, Etienne

2012-05-01

Identifying gastroduodenal uptake of (99m)Tc-macroaggregated albumin (MAA), which is associated with an increased risk of ulcer disease, is a crucial part of the therapeutic management of patients undergoing radioembolization for liver tumours. Given this context, the use of MAA single photon emission computed tomography (SPECT)/CT may be essential, but the procedure has still not been thoroughly evaluated. The aim of this retrospective study was to determine the effectiveness of MAA SPECT/CT in identifying digestive extrahepatic uptake, while determining potential diagnostic pitfalls. Overall, 139 MAA SPECT/CT scans were performed on 103 patients with different hepatic tumour types. Patients were followed up for at least 6 months according to standard requirements. Digestive, or digestive-like, uptake other than free pertechnetate was identified in 5.7% of cases using planar imaging and in 36.6% of cases using SPECT/CT. Uptake sites identified by SPECT/CT included the gastroduodenal region (3.6%), gall bladder (12.2%), portal vein thrombosis (6.5%), hepatic artery (6.5%), coil embolization site (2.1%) as well as falciform artery (5.0%). For 2.1% of explorations, a coregistration error between SPECT and CT imaging could have led to a false diagnosis by erroneously attributing an uptake site to the stomach or gall bladder, when the uptake actually occurred in the liver. SPECT/CT is more efficacious than planar imaging in identifying digestive extrahepatic uptake sites, with extrahepatic uptake observed in one third of scans using the former procedure. However, more than half of the uptake sites in our study were vascular in nature, without therapeutic implications. The risk of coregistration errors must also be kept in mind.

Human erythrocytes transport dehydroascorbic acid and sugars using the same transporter complex

PubMed Central

Sage, Jay M.

2014-01-01

GLUT1, the primary glucose transport protein in human erythrocytes [red blood cells (RBCs)], also transports oxidized vitamin C [dehydroascorbic acid (DHA)]. A recent study suggests that RBC GLUT1 transports DHA as its primary substrate and that only a subpopulation of GLUT1 transports sugars. This conclusion is based on measurements of cellular glucose and DHA equilibrium spaces, rather than steady-state transport rates. We have characterized RBC transport of DHA and 3-O-methylglucose (3-OMG), a transported, nonmetabolizable sugar. Steady-state 3-OMG and DHA uptake in the absence of intracellular substrate are characterized by similar Vmax (0.16 ± 0.01 and 0.13 ± 0.02 mmol·l−1·min−1, respectively) and apparent Km (1.4 ± 0.2 and 1.6 ± 0.7 mM, respectively). 3-OMG and DHA compete for uptake, with Ki(app) of 0.7 ± 0.4 and 1.1 ± 0.1 mM, respectively. Uptake measurements using RBC inside-out-membrane vesicles demonstrate that 3-OMG and DHA compete at the cytoplasmic surface of the membrane, with Ki(app) of 0.7 ± 0.1 and 0.6 ± 0.1 mM, respectively. Intracellular 3-OMG stimulates unidirectional uptake of 3-OMG and DHA. These findings indicate that DHA and 3-OMG bind at mutually exclusive sites at exo- and endofacial surfaces of GLUT1 and are transported via the same GLUT1 complex. PMID:24598365

Human erythrocytes transport dehydroascorbic acid and sugars using the same transporter complex.

PubMed

Sage, Jay M; Carruthers, Anthony

2014-05-15

GLUT1, the primary glucose transport protein in human erythrocytes [red blood cells (RBCs)], also transports oxidized vitamin C [dehydroascorbic acid (DHA)]. A recent study suggests that RBC GLUT1 transports DHA as its primary substrate and that only a subpopulation of GLUT1 transports sugars. This conclusion is based on measurements of cellular glucose and DHA equilibrium spaces, rather than steady-state transport rates. We have characterized RBC transport of DHA and 3-O-methylglucose (3-OMG), a transported, nonmetabolizable sugar. Steady-state 3-OMG and DHA uptake in the absence of intracellular substrate are characterized by similar Vmax (0.16 ± 0.01 and 0.13 ± 0.02 mmol·l(-1)·min(-1), respectively) and apparent Km (1.4 ± 0.2 and 1.6 ± 0.7 mM, respectively). 3-OMG and DHA compete for uptake, with Ki(app) of 0.7 ± 0.4 and 1.1 ± 0.1 mM, respectively. Uptake measurements using RBC inside-out-membrane vesicles demonstrate that 3-OMG and DHA compete at the cytoplasmic surface of the membrane, with Ki(app) of 0.7 ± 0.1 and 0.6 ± 0.1 mM, respectively. Intracellular 3-OMG stimulates unidirectional uptake of 3-OMG and DHA. These findings indicate that DHA and 3-OMG bind at mutually exclusive sites at exo- and endofacial surfaces of GLUT1 and are transported via the same GLUT1 complex. Copyright © 2014 the American Physiological Society.

A study of the uptake of chloroquine in malaria-infected erythrocytes. High and low affinity uptake and the influence of glucose and its analogues.

PubMed

Diribe, C O; Warhurst, D C

1985-09-01

A study of concentration- and substrate-dependence of chloroquine uptake has been carried out on mouse erythrocytes infected with the chloroquine-sensitive NK65 and the chloroquine-resistant RC strains of Plasmodium berghei. The presence of drug binding sites of high and low affinity in such strains of P. berghei was confirmed. High affinity uptake sites in cells parasitized with chloroquine-sensitive and chloroquine-resistant parasites have similar characteristics, but in the sensitive strain the major component of chloroquine-uptake is at high affinity and dependent on the availability of ATP whilst in the resistant strain the major component of uptake is at low affinity and independent of energy. An absolute increase in the quantity of the low affinity site in erythrocytes parasitized with chloroquine-resistant P. berghei was noted, which may be related to an increase in quantity of parasite membrane.

5-HT receptor probe (/sup 3/H)8-OH-DPAT labels the 5-HT transporter in human platelets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ieni, J.R.; Meyerson, L.R.

1988-01-01

The present study characterizes a serotonin (5-HT) binding site on human platelet membranes, using (/sup 3/H)8-OH-DPAT as the radioligand. (/sup 3/H)8-OH-DPAT binds specifically and saturably to a site on human platelet membranes with an average K/sub D/ of 43 nM and B/sub max/ of 1078 fmol/mg protein. Determinations of IC/sub 50/ values for various serotonergic characterizing agents in platelets for displacement of (/sup 3/H)8-OH-DPAT were performed. The pharmacological inhibitory profile of the platelet 8-OH-DPAT site is not consistent with profiles reported for brain. 8-OH-DPAT does not inhibit (/sup 3/H) imipramine binding, however, it does inhibit (/sup 3/H)5-HT uptake in humanmore » platelets near 5-HT's K/sub m/ value (IC/sub 50/ = 2-4 ..mu..M). These results suggest that the human platelet site labelled by (/sub 3/H)8-OH-DPAT is pharmocologically different from the neuronal site and probably is a component of the 5-HT transporter. 32 references, 1 figure, 4 tables.« less

Neuroendocrine tumor imaging with 68Ga-DOTA-NOC: physiologic and benign variants.

PubMed

Kagna, Olga; Pirmisashvili, Natalia; Tshori, Sagi; Freedman, Nanette; Israel, Ora; Krausz, Yodphat

2014-12-01

Imaging with (68)Ga-labeled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-octreotide analogs has become an important modality in patients with neuroendocrine tumors (NETs). In addition to high uptake in NET lesions, prominent physiologic radiotracer activity has been reported in the pituitary gland, pancreas, adrenal glands, liver, and spleen, and faint activity has been reported in the thyroid and gastrointestinal tract. This article describes previously unknown sites of 68Ga-DOTA-1-NaI3-octreotide (NOC) uptake unrelated to NETs. One hundred eighty-two patients (96 female and 86 male patients; age range, 4-89 years) with documented (n=156) or suspected (n=26) NETs underwent 207 68Ga-DOTA-NOC PET/CT studies. Studies were retrospectively reviewed for the presence, intensity, and localization of foci of increased uptake that were further correlated with findings on additional imaging studies and clinical follow-up for a period of 4-32 months. Uptake of 68Ga-DOTA-NOC not identified as NET or known physiologic activity was detected in 297 sites with confirmation in 149 of 207 studies (72%). The most common location of non-NET-related 68Ga-DOTA-NOC-avid sites was in small lymph nodes, followed by prostate, uterus, breasts, lungs, brown fat, musculoskeletal system, and other sites, including oropharynx, pineal body, thymus, aortic plaque, genitalia, surgical bed, and subcutaneous granuloma. Intensity of uptake in non-NET-related 68Ga-DOTA-NOC-avid sites ranged in maximum standardized uptake value from 0.8 to 10.5. Previously unreported benign sites of 68Ga-DOTA-NOC uptake were found in the majority of studies, suggesting the presence of somatostatin receptors in physiologic variants or processes with no evidence of tumor. Knowledge of increased tracer uptake in non-NET-related sites is important for accurate interpretation and for avoiding potential pitfalls of 68Ga-DOTA-NOC PET/CT.

Functional characterization of the dimerization domain of the ferric uptake regulator (Fur) of Pseudomonas aeruginosa

PubMed Central

Bai, Erdeni; Rosell, Federico I.; Lige, Bao; Mauk, Marcia R.; Lelj-Garolla, Barbara; Moore, Geoffrey R.; Mauk, A. Grant

2006-01-01

The functional properties of the recombinant C-terminal dimerization domain of the Pseudomonas aeruginosa Fur (ferric uptake regulator) protein expressed in and purified from Escherichia coli have been evaluated. Sedimentation velocity measurements demonstrate that this domain is dimeric, and the UV CD spectrum is consistent with a secondary structure similar to that observed for the corresponding region of the crystallographically characterized wild-type protein. The thermal stability of the domain as determined by CD spectroscopy decreases significantly as pH is increased and increases significantly as metal ions are added. Potentiometric titrations (pH 6.5) establish that the domain possesses a high-affinity and a low-affinity binding site for metal ions. The high-affinity (sensory) binding site demonstrates association constants (KA) of 10(±7)×106, 5.7(±3)×106, 2.0(±2)×106 and 2.0(±3)×104 M−1 for Ni2+, Zn2+, Co2+ and Mn2+ respectively, while the low-affinity (structural) site exhibits association constants of 1.3(±2)×106, 3.2(±2)×104, 1.76(±1)×105 and 1.5(±2)×103 M−1 respectively for the same metal ions (pH 6.5, 300 mM NaCl, 25 °C). The stability of metal ion binding to the sensory site follows the Irving–Williams order, while metal ion binding to the partial sensory site present in the domain does not. Fluorescence experiments indicate that the quenching resulting from binding of Co2+ is reversed by subsequent titration with Zn2+. We conclude that the domain is a reasonable model for many properties of the full-length protein and is amenable to some analyses that the limited solubility of the full-length protein prevents. PMID:16928194

Structure of GlnK1 with bound effectors indicates regulatory mechanism for ammonia uptake.

PubMed

Yildiz, Ozkan; Kalthoff, Christoph; Raunser, Stefan; Kühlbrandt, Werner

2007-01-24

A binary complex of the ammonia channel Amt1 from Methanococcus jannaschii and its cognate P(II) signalling protein GlnK1 has been produced and characterized. Complex formation is prevented specifically by the effector molecules Mg-ATP and 2-ketoglutarate. Single-particle electron microscopy of the complex shows that GlnK1 binds on the cytoplasmic side of Amt1. Three high-resolution X-ray structures of GlnK1 indicate that the functionally important T-loop has an extended, flexible conformation in the absence of Mg-ATP, but assumes a compact, tightly folded conformation upon Mg-ATP binding, which in turn creates a 2-ketoglutarate-binding site. We propose a regulatory mechanism by which nitrogen uptake is controlled by the binding of both effector molecules to GlnK1. At normal effector levels, a 2-ketoglutarate molecule binding at the apex of the compact T-loop would prevent complex formation, ensuring uninhibited ammonia uptake. At low levels of Mg-ATP, the extended loops would seal the ammonia channels in the complex. Binding of both effector molecules to P(II) signalling proteins may thus represent an effective feedback mechanism for regulating ammonium uptake through the membrane.

Foliar concentrations of volunteer willows growing on polluted sediment-derived sites versus sites with baseline contamination levels.

PubMed

Vandecasteele, Bart; Quataert, Paul; De Vos, Bruno; Tack, Filip M G; Muys, Bart

2004-04-01

Many alluvial soils along navigable waterways are affected by disposal of dredged sediments or overbank sedimentation and contain metal concentrations that are elevated compared to baseline levels. Uptake patterns for metals and other elements by several volunteer Salix species growing on these sites were determined during a growing season in field plots and compared with the same species growing on soils with baseline contamination levels. For Cd and Zn, foliar concentrations were clearly higher on dredged sediment landfills. Uptake patterns differed significantly between species. A high uptake of Mn and low uptake of Cu, K and S in S. cinerea was attributed to wetland soil chemistry. Site effects on metal uptake were evaluated in more detail for Salix cinerea and S. alba growing on different sediment-derived sites under field conditions. Foliar Cd concentrations were higher in S. cinerea than in S. alba. This appeared to be a genetic feature not influenced by soil chemical properties, as it was observed both on clean sites and polluted sediment-derived sites. For S. cinerea, soil chemistry was reflected in foliar concentrations, while foliar Cd concentrations and bioavailability were found to be independent of the thickness of the polluted horizon. Dredged sediment landfills and freshwater tidal marshes with comparable Cd soil pollution had significantly different foliar Cd concentrations.

Fundamentals of pulmonary drug delivery.

PubMed

Groneberg, D A; Witt, C; Wagner, U; Chung, K F; Fischer, A

2003-04-01

Aerosol administration of peptide-based drugs plays an important role in the treatment of pulmonary and systemic diseases and the unique cellular properties of airway epithelium offers a great potential to deliver new compounds. As the relative contributions from the large airways to the alveolar space are important to the local and systemic availability, the sites and mechanism of uptake and transport of different target compounds have to be characterized. Among the different respiratory cells, the ciliated epithelial cells of the larger and smaller airways and the type I and type II pneumocytes are the key players in pulmonary drug transport. With their diverse cellular characteristics, each of these cell types displays a unique uptake possibility. Next to the knowledge of these cellular aspects, the nature of aerosolized drugs, characteristics of delivery systems and the depositional and pulmonary clearance mechanisms display major targets to optimize pulmonary drug delivery. Based on the growing knowledge on pulmonary cell biology and pathophysiology due to modern methods of molecular biology, the future characterization of pulmonary drug transport pathways can lead to new strategies in aerosol drug therapy.

[Adrenal incidentaloma and nuclear medicine examination].

PubMed

Tenenbaum, F

2009-03-01

In the setting of adrenal incidentaloma, nuclear medicine evaluation is only indicated after biological and imaging work-up has been completed. MIBG scintigraphy is helpful to characterize pheochromocytomas. In lesions without MIBG uptake, 18F FDG or 18F DOPA PET can be considered to characterize chromaffin cell tumours. To characterize lesions of the adrenal cortex, iodocholesterol scintigraphy is performed to confirm the origin of the adenoma and the benign or malignant nature of the lesion since benign adenomas show tracer uptake and malignant lesions show no tracer uptake. 18F FDG PET only characterizes the lesion as benign or malignant.

Low transient storage and uptake efficiencies in seven agricultural streams: implications for nutrient demand

USGS Publications Warehouse

Sheibley, Rich W.; Duff, John H.; Tesoriero, Anthony J.

2014-01-01

We used mass load budgets, transient storage modeling, and nutrient spiraling metrics to characterize nitrate (NO3−), ammonium (NH4+), and inorganic phosphorus (SRP) demand in seven agricultural streams across the United States and to identify in-stream services that may control these conditions. Retention of one or all nutrients was observed in all but one stream, but demand for all nutrients was low relative to the mass in transport. Transient storage metrics (As/A, Fmed200, Tstr, and qs) correlated with NO3− retention but not NH4+ or SRP retention, suggesting in-stream services associated with transient storage and stream water residence time could influence reach-scale NO3− demand. However, because the fraction of median reach-scale travel time due to transient storage (Fmed200) was ≤1.2% across the sites, only a relatively small demand for NO3− could be generated by transient storage. In contrast, net uptake of nutrients from the water column calculated from nutrient spiraling metrics were not significant at any site because uptake lengths calculated from background nutrient concentrations were statistically insignificant and therefore much longer than the study reaches. These results suggest that low transient storage coupled with high surface water NO3− inputs have resulted in uptake efficiencies that are not sufficient to offset groundwater inputs of N. Nutrient retention has been linked to physical and hydrogeologic elements that drive flow through transient storage areas where residence time and biotic contact are maximized; however, our findings indicate that similar mechanisms are unable to generate a significant nutrient demand in these streams relative to the loads.

Understanding the in vivo uptake kinetics of a phosphatidylethanolamine-binding agent 99mTc-Duramycin

PubMed Central

Audi, Said; Li, Zhixin; Capacete, Joseph; Liu, Yu; Fang, Wei; Shu, Laura G.; Zhao, Ming

2013-01-01

Introduction 99mTc-Duramycin is a peptide-based molecular probe that binds specifically to phosphatidylethanolamine (PE). The goal was to characterize the kinetics of molecular interactions between 99mTc-Duramycin and the target tissue. Methods High level of accessible PE is induced in cardiac tissues by myocardial ischemia (30 min) and reperfusion (120 min) in Sprague Dawley rats. Target binding and biodistribution of 99mTc-duramycin was captured using SPECT/CT. To quantify the binding kinetics, the presence of radioactivity in ischemic versus normal cardiac tissues was measured by gamma counting at 3, 10, 20, 60 and 180 min after injection. A partially inactivated form of 99mTc-Duramycin was analyzed in the same fashion. A compartment model was developed to quantify the uptake kinetics of 99mTc-Duramycin in normal and ischemic myocardial tissue. Results 99mTc-duramycin binds avidly to the damaged tissue with a high target-to-background radio. Compartment modeling shows that accessibility of binding sites in myocardial tissue to 99mTc-Duramycin is not a limiting factor and the rate constant of target binding in the target tissue is at 2.2 ml/nmol/min/g. The number of available binding sites for 99mTc-Duramycin in ischemic myocardium was estimated at 0.14 nmol/g. Covalent modification of D15 resulted in a 9 fold reduction in binding affinity. Conclusion 99mTc-Duramycin accumulates avidly in target tissues in a PE-dependent fashion. Model results reflect an efficient uptake mechanism, consistent with the low molecular weight of the radiopharmaceutical and the relatively high density of available binding sites. These data help better define the imaging utilities of 99mTc-Duramycin as a novel PE-binding agent. PMID:22534031

Characterization of the hupSL promoter activity in Nostoc punctiforme ATCC 29133

PubMed Central

2009-01-01

Background In cyanobacteria three enzymes are directly involved in the hydrogen metabolism; a nitrogenase that produces molecular hydrogen, H2, as a by-product of nitrogen fixation, an uptake hydrogenase that recaptures H2 and oxidize it, and a bidirectional hydrogenase that can both oxidize and produce H2.Nostoc punctiforme ATCC 29133 is a filamentous dinitrogen fixing cyanobacterium containing a nitrogenase and an uptake hydrogenase but no bidirectional hydrogenase. Generally, little is known about the transcriptional regulation of the cyanobacterial uptake hydrogenases. In this study gel shift assays showed that NtcA has a specific affinity to a region of the hupSL promoter containing a predicted NtcA binding site. The predicted NtcA binding site is centred at 258.5 bp upstream the transcription start point (tsp). To further investigate the hupSL promoter, truncated versions of the hupSL promoter were fused to either gfp or luxAB, encoding the reporter proteins Green Fluorescent Protein and Luciferase, respectively. Results Interestingly, all hupsSL promoter deletion constructs showed heterocyst specific expression. Unexpectedly the shortest promoter fragment, a fragment covering 57 bp upstream and 258 bp downstream the tsp, exhibited the highest promoter activity. Deletion of the NtcA binding site neither affected the expression to any larger extent nor the heterocyst specificity. Conclusion Obtained data suggest that the hupSL promoter in N. punctiforme is not strictly dependent on the upstream NtcA cis element and that the shortest promoter fragment (-57 to tsp) is enough for a high and heterocyst specific expression of hupSL. This is highly interesting because it indicates that the information that determines heterocyst specific gene expression might be confined to this short sequence or in the downstream untranslated leader sequence. PMID:19284581

Studies on the lithium transport across the red cell membrane. II. Characterization of ouabain-sensitive and ouabain-insensitive Li+ transport. Effects of bicarbonate and dipyridamole.

PubMed

Duhm, J; Becker, B F

1977-01-17

In studies on Li+ net-transport across the human red cell membrane following results were obtained: 1. In K+- and Na+-free choline chloride media, Li+ is transported into the erythrocytes against an electrochemical gradient. This Li+ uphill transport as well as Li+ downhill transport into the cells is inhibited by ouabain, ATP-depletion, and by external K+ and Na+. The effects of K+ and Na+ are relieved at high Li+ concentrations. 2. Ouabain-sensitive Li+ uptake, determined at 10 mM external Na+, does not obey simple Michaelis-Menten kinetics and exhibits a maximum at about pH 7. 3. Ouabain-resistant Li+ downhill transport into erythrocytes increases with rising pH. It is comprised of a saturating component and a component linearly dependent on external Li+. The linear component is partly inhibited by dipyridamole and accelerated by bicarbonate. The bicarbonate effect can be completely blocked by dipyridamole, phlorizin and phenylbutazone. 4. Li+ release is not inhibited by ouabain, ATP-depletion and external K+. It increases with external Na+ concentration, tending to saturate at 150 mM Na+. Na+-independent Li+ release is stimulated by bicarbonate. It is concluded that ouabain-sensitive Li+ uptake is mediated at the K+-site(s) of the Na+-K+ pump. Li+, K+ and Na+ appear to compete for a common site (or sites). The stimulation of Li+ transfer by bicarbonate and the inhibition by dipyridamole suggest a participation of anionic species in ouabain-resistant Li+ transfer. The Na+-dependent Li+ release and the "saturating component" of Li+ uptake are ascribed to the Na+-dependent Li+ countertransport system.

Combining multiple ecosystem productivity measurements to constrain carbon uptake estimates in semiarid grasslands and shrublands

NASA Astrophysics Data System (ADS)

Maurer, G. E.; Krofcheck, D. J.; Collins, S. L.; Litvak, M. E.

2016-12-01

Recent observational and modeling studies have indicated that semiarid ecosystems are more dynamic contributors to the global carbon budget than once thought. Semiarid carbon fluxes, however, are generally small, with high interannual and spatial variability, which suggests that validating their global significance may depend on examining multiple productivity measures and their associated uncertainties and inconsistencies. We examined ecosystem productivity from eddy covariance (NEE), harvest (NPP), and terrestrial biome models (NEPm) at two very similar grassland sites and one creosote shrubland site in the Sevilleta National Wildlife Refuge of central New Mexico, USA. Our goal was to assess site and methodological correspondence in annual carbon uptake, patterns of interannual variability, and measurement uncertainty. One grassland site was a perennial carbon source losing 30 g C m-2 per year on average, while the other two sites were carbon sources or sinks depending on the year, with average net uptake of 5 and 25 g C m-2 per year at the grassland and shrubland site, respectively. Uncertainty values for cumulative annual NEE overlapped between the three sites in most years. When combined, aboveground and belowground annual NPP measurements were 15% higher than annual NEE values and did not confirm a loss of carbon at any site in any year. Despite differences in mean site carbon balance, year-to-year changes in cumulative annual NEE and NPP were similar at all sites with years 2010 and 2013 being favorable for carbon uptake and 2011 and 2012 being unfavorable at all sites. Modeled NEPm data for a number of nearby grid cells reproduced only a fraction of the observed range in carbon uptake and its interannual variability. These three sites are highly similar in location and climate and multiple carbon flux measurements confirm the high interannual variability in carbon flux. The exact magnitude of these fluxes, however, remains difficult to discern.

Characterization of Cadmium Uptake by Plant Tissue 12

PubMed Central

Cutler, Jay M.; Rains, Donald W.

1974-01-01

The uptake of cadmium by excised root tissue of barley (Hordeum vulgare L. cv. Arivat) was investigated with respect to kinetics, concentration, and interactions with various cations. The role of metabolism in Cd absorption was examined using a range of temperatures, anaerobic treatments, and chemical inhibitors. The uptake and distribution of Cd in intact barley plants was also determined. A large fraction of the Cd taken up by excised barley roots was apparently the result of exchange adsorption and was displaced by subsequent desorption with unlabeled Cd, Zn, Cu, or Hg. Another fraction of Cd which could not be displaced by desorption in unlabeled Cd was thought to result from strong irreversible binding of Cd, perhaps on sites of the cell wall. The fraction of the Cd taken up beyond that by exchange adsorption by fresh roots was a linear function of temperature, and inhibited by conditions of low oxygen and by the presence of 2,4-dinitrophenol. It was concluded that this fraction of Cd entered excised barley roots by diffusion. Diffusion, when followed by sequestering, probably accounts for the accumulation of Cd observed in intact barley plants. PMID:16658840

Effects of high-dose fenfluramine treatment on monoamine uptake sites in rat brain: Assessment using quantitative autoradiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Appel, N.M.; Mitchell, W.M.; Contrera, J.F.

1990-01-01

Fenfluramine is an amphetamine derivative that in humans is used primarily as an anorectic agent in the treatment of obesity. In rats, subchronic high-dose d,l-fenfluramine treatment (24 mg/kg subcutaneously, twice daily for 4 days) causes long-lasting decreases in brain serotonin (5HT), its metabolite 5-hydroxyindoleacetic acid, and high-affinity 5HT uptake sites. Moreover, this high-dose treatment regimen causes both selective long-lasting decreases in fine-caliber 5HT-immunoreactive axons and appearance of other 5HT-immunoreactive axons with morphology characteristic of degenerating axons. Determination of the potential neurotoxic effects of fenfluramine treatment using immunohistochemistry is limited from the perspectives that staining is difficult to quantify and thatmore » it relies on presence of the antigen (in this case 5HT), and the 5HT-depleting effects of fenfluramine are well known. In the present study, we used quantitative in vitro autoradiography to assess, in detail, the density and regional distribution of (3H)paroxetine-labeled 5HT and (3H)mazindol-labeled catecholamine uptake sites in response to the high-dose fenfluramine treatment described above. Because monoamine uptake sites are concentrated on monoamine-containing nerve terminals, decreases in uptake site density would provide a quantitative assessment of potential neurotoxicity resulting from this fenfluramine treatment regimen. Marked decreases in densities of (3H)paroxetine-labeled 5HT uptake sites occurred in brain regions in which fenfluramine treatment decreased the density of 5HT-like immunostaining when compared to saline-treated control rats. These included cerebral cortex, caudate putamen, hippocampus, thalamus, and medial hypothalamus.« less

Uptake of choline by rat mammary-gland epithelial cells.

PubMed Central

Chao, C K; Pomfret, E A; Zeisel, S H

1988-01-01

The neonatal mammal requires especially large amounts of choline to sustain growth. Much of this choline is derived from the newborn's only source of food, milk. The concentration of choline in rat milk [182 +/- 24 microM (S.E.M.)] was much higher than that in maternal serum (11.6 +/- 0.9 microM), suggesting that a mechanism capable of concentrating choline into milk must exist. We characterized choline uptake by mammary epithelial cells (the site of milk production) of the lactating rat. We observed two uptake processes, one saturable and obeying Michaelis-Menten kinetics, and the other non-saturable and linear. At physiological blood choline concentrations, the saturable component of choline uptake predominated. The saturable component had Kapp. = 35 +/- 16 microM, and Vmax. = 1.24 +/- 0.19 nmol/h per mg of protein. Saturable uptake of choline was inhibited by hemicholinium-3. Ca2+ was required for uptake, but Mg2+ was not. Replacement Na+ with K+, Li+ or sucrose inhibited transport. Ouabain did not inhibit choline uptake. Choline concentration in epithelial cells was 67.7 +/- 1.9 nmol/g wet wt. at the start of incubation at 37 degrees C and rose to 80.9 +/- 6.5 nmol/g wet wt. over 30 min. Much of the choline accumulated by the mammary gland (in the presence of endogenous concentrations of choline) remained in the form of choline (50 +/- 1.2%), phosphatidylcholine (12 +/- 2.3%), lysophosphatidylcholine (0.1 +/- 0.03%), betaine (7 +/- 0.3% and phosphocholine (6 +/- 0.5%). In addition, we isolated 25 +/- 1.2% of choline-derived radiolabel in an unidentified compound. Images Fig. 1. Fig. 3. PMID:3178755

Autoradiographic localization of /sup 3/H-paroxetine-labeled serotonin uptake sites in rat brain

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Souza, E.B.; Kuyatt, B.L.

1987-01-01

Paroxetine is a potent and selective inhibitor of serotonin uptake into neurons. Serotonin uptake sites have been identified, localized, and quantified in rat brain by autoradiography with 3H-paroxetine; 3H-paroxetine binding in slide-mounted sections of rat forebrain was of high affinity (KD = 10 pM) and the inhibition affinity constant (Ki) values of various drugs in competing 3H-paroxetine binding significantly correlated with their reported potencies in inhibiting synaptosomal serotonin uptake. Serotonin uptake sites labeled by 3H-paroxetine were highly concentrated in the dorsal and median raphe nuclei, central gray, superficial layer of the superior colliculus, lateral septal nucleus, paraventricular nucleus of themore » thalamus, and the islands of Calleja. High concentrations of 3H-paroxetine binding sites were found in brainstem areas containing dopamine (substantia nigra and ventral tegmental area) and norepinephrine (locus coeruleus) cell bodies. Moderate concentrations of 3H-paroxetine binding sites were present in laminae I and IV of the frontal parietal cortex, primary olfactory cortex, olfactory tubercle, regions of the basal ganglia, septum, amygdala, thalamus, hypothalamus, hippocampus, and some brainstem areas including the interpeduncular, trigeminal, and parabrachial nuclei. Lower densities of 3H-paroxetine binding sites were found in other regions of the neocortex and very low to nonsignificant levels of binding were present in white matter tracts and in the cerebellum. Lesioning of serotonin neurons with 3,4-methylenedioxyamphetamine caused large decreases in 3H-paroxetine binding. The autoradiographic distribution of 3H-paroxetine binding sites in rat brain corresponds extremely well to the distribution of serotonin terminals and cell bodies as well as with the pharmacological sites of action of serotonin.« less

Interaction between phloretin and the red blood cell membrane

PubMed Central

1976-01-01

Phloretin binding to red blood cell components has been characterized at pH6, where binding and inhibitory potency are maximal. Binding to intact red cells and to purified hemoglobin are nonsaturated processes approximately equal in magnitude, which strongly suggests that most of the red cell binding may be ascribed to hemoglobin. This conclusion is supported by the fact that homoglobin-free red cell ghosts can bind only 10% as much phloretin as an equivalent number of red cells. The permeability of the red cell membrane to phloretin has been determined by a direct measurement at the time-course of the phloretin uptake. At a 2% hematocrit, the half time for phloretin uptake is 8.7s, corresponding to a permeability coefficient of 2 x 10(-4) cm/s. The concentration dependence of the binding to ghosts reveals two saturable components. Phloretin binds with high affinity (K diss = 1.5 muM) to about 2.5 x 10(6) sites per cell; it also binds with lower affinity (Kdiss = 54 muM) to a second (5.5 x 10(7) per cell) set of sites. In sonicated total lipid extracts of red cell ghosts, phloretin binding consists of a single, saturable component. Its affinity and total number of sites are not significantly different from those of the low affinity binding process in ghosts. No high affinity binding of phloretin is exhibited by the red cell lipid extracts. Therefore, the high affinity phloretin binding sites are related to membrane proteins, and the low affinity sites result from phloretin binding to lipid. The identification of these two types of binding sites allows phloretin effects on protein-mediated transport processes to be distinguished from effects on the lipid region of the membrane. PMID:5575

Harmane: an atypical neurotransmitter?

PubMed

Abu Ghazaleh, Haya; Lalies, Maggie D; Nutt, David J; Hudson, Alan L

2015-03-17

Harmane is an active component of clonidine displacing substance and a candidate endogenous ligand for imidazoline binding sites. The neurochemistry of tritiated harmane was investigated in the present study examining its uptake and release properties in the rat brain central nervous system (CNS) in vitro. At physiological temperature, [(3)H]harmane was shown to be taken up in rat brain cortex. Further investigations demonstrated that treatment with monoamine uptake blockers (citalopram, nomifensine and nisoxetine) did not alter [(3)H]harmane uptake implicating that the route of [(3)H]harmane transport was distinct from the monoamine uptake systems. Furthermore, imidazoline ligands (rilmenidine, efaroxan, 2-BFI and idazoxan) showed no prominent effect on [(3)H]harmane uptake suggesting the lack of involvement of imidazoline binding sites. Subsequent analyses showed that disruption of the Na(+) gradient using ouabain or choline chloride did not block [(3)H]harmane uptake suggesting a Na(+)-independent transport mechanism. Moreover, higher temperatures (50°C) failed to impede [(3)H]harmane uptake implying a non-physiological transporter. The failure of potassium to evoke the release of preloaded [(3)H]harmane from rat brain cortex indicates that the properties of this putative endogenous ligand for imidazoline binding sites do not resemble that of a conventional neurotransmitter. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Ga-68 DOTA-NOC uptake in the pancreas: pathological and physiological patterns.

PubMed

Krausz, Yodphat; Rubinstein, Rina; Appelbaum, Liat; Mishani, Eyal; Orevi, Marina; Fraenkel, Merav; Tshori, Sagi; Glaser, Benjamin; Bocher, Moshe; Salmon, Asher; Chisin, Roland; Gross, David J; Freedman, Nanette

2012-01-01

Gallium-68 (Ga-68) DOTA-1-NaI3-octreotide (DOTA-NOC) positron emission tomography (PET)/computed tomography (CT) is increasingly used for neuroendocrine tumors (NETs), often found primarily in the pancreas. However, physiologic uptake of DOTA-NOC has been described in the uncinate process of the pancreas. We studied DOTA-NOC uptake in this organ. Ninety-six patients underwent 103 DOTA-NOC scans, with pathology-proven pancreatic NET (n = 40) and nonpancreatic NET or biochemical suspicion of NET (n = 63). DOTA-NOC uptake was detected in 35 documented pancreatic tumor sites (SUV: 5.5-165; mean: 25.7 ± 28.8; median: 17.8). Among 63 cases without previous known pathology, uptake was suspicious for tumor in 24 sites (SUV: 4.7-35; mean 16.3 ± 8.0; median: 14.1), and in 38 sites, it was judged as physiological, generally lower relative to adjacent structures (SUV: 2.2-12.6; mean: 6.6 ± 2.2; median: 6.2). In 24 scans with suspected tumor and in 37 of 38 scans with physiological uptake, diagnostic computed tomography or magnetic resonance imaging or endoscopic ultrasonography failed to detect tumor. Pancreatic DOTA-NOC uptake must be interpreted with caution, and further studies are required.

Interactive effects of nocturnal transpiration and climate change on the root hydraulic redistribution and carbon and water budgets of southern United States pine plantations.

PubMed

Domec, Jean-Christophe; Ogée, Jérôme; Noormets, Asko; Jouangy, Julien; Gavazzi, Michael; Treasure, Emrys; Sun, Ge; McNulty, Steve G; King, John S

2012-06-01

Deep root water uptake and hydraulic redistribution (HR) have been shown to play a major role in forest ecosystems during drought, but little is known about the impact of climate change, fertilization and soil characteristics on HR and its consequences on water and carbon fluxes. Using data from three mid-rotation loblolly pine plantations, and simulations with the process-based model MuSICA, this study indicated that HR can mitigate the effects of soil drying and had important implications for carbon uptake potential and net ecosystem exchange (NEE), especially when N fertilization is considered. At the coastal site (C), characterized by deep organic soil, HR increased dry season tree transpiration (T) by up to 40%, and such an increase affected NEE through major changes in gross primary productivity (GPP). Deep-rooted trees did not necessarily translate into a large volume of HR unless soil texture allowed large water potential gradients to occur, as was the case at the sandy site (S). At the Piedmont site (P) characterized by a shallow clay-loam soil, HR was low but not negligible, representing up to 10% of T. In the absence of HR, it was predicted that at the C, S and P sites, annual GPP would have been diminished by 19, 7 and 9%, respectively. Under future climate conditions HR was predicted to be reduced by up to 25% at the C site, reducing the resilience of trees to precipitation deficits. The effect of HR on T and GPP was predicted to diminish under future conditions by 12 and 6% at the C and P sites, respectively. Under future conditions, T was predicted to stay the same at the P site, but to be marginally reduced at the C site and slightly increased at the S site. Future conditions and N fertilization would decrease T by 25% at the C site, by 15% at the P site and by 8% at the S site. At the C and S sites, GPP was estimated to increase by 18% and by >70% under future conditions, respectively, with little effect of N fertilization. At the P site, future conditions would stimulate GPP by only 12%, but future conditions plus N fertilization would increase GPP by 24%. As a consequence, in all sites, water use efficiency was predicted to improve dramatically with future conditions. Modeling the effect of reduced annual precipitation indicated that limited water availability would decrease all carbon fluxes, including NEE and respiration. Our simulations highlight the interactive effects of nutrients and elevated CO(2), and showed that the effect of N fertilization would be greater under future climate conditions.

Stomata open at night in pole-sized and mature ponderosa pine: implications for O3 exposure metrics.

PubMed

Grulke, N E; Alonso, R; Nguyen, T; Cascio, C; Dobrowolski, W

2004-09-01

Ponderosa pine (Pinus ponderosa Dougl. ex Laws.) is widely distributed in the western USA. We report the lack of stomatal closure at night in early summer for ponderosa pine at two of three sites investigated. Trees at a third site with lower nitrogen dioxide and nitric acid exposure, but greater drought stress, had slightly open stomata at night in early summer but closed stomata at night for the rest of the summer. The three sites had similar background ozone exposure during the summer of measurement (2001). Nighttime stomatal conductance (gs) ranged from one tenth to one fifth that of maximum daytime values. In general, pole-sized trees (< 40 years old) had greater nighttime gs than mature trees (> 250 years old). In late summer, nighttime gs was low (< 3.0 mmol H2O m(-2) s(-1)) for both tree size classes at all sites. Measurable nighttime gs has also been reported in other conifers, but the values we observed were higher. In June, nighttime ozone (O3) uptake accounted for 9, 5 and 3% of the total daily O3 uptake of pole-sized trees from west to east across the San Bernardino Mountains. In late summer, O3 uptake at night was < 2% of diel uptake at all sites. Nocturnal O3 uptake may contribute to greater oxidant injury development, especially in pole-sized trees in early summer.

Atmospheric CO and hydrogen uptake and CO oxidizer phylogeny for miyake-jima, Japan volcanic deposits.

PubMed

King, Gary M; Weber, Carolyn F; Nanba, Kenji; Sato, Yoshinori; Ohta, Hiroyuki

2008-01-01

We have assayed rates of atmospheric CO and hydrogen uptake, maximum potential CO uptake and the major phylogenetic composition of CO-oxidizing bacterial communities for a variety of volcanic deposits on Miyake-jima, Japan. These deposits represented different ages and stages of plant succession, ranging from unvegetated scoria deposited in 1983 to forest soils on deposits >800 yr old. Atmospheric CO and hydrogen uptake rates varied from -2.0±1.8-6.3±0.1 mg CO m(-2) d(-1) and 0.0±0.4-2.0±0.2 mg H(2) m(-2) d(-1), respectively, and were similar to or greater than values reported for sites on Kilauea volcano, Hawaii, USA. At one of the forested sites, CO was emitted to the atmosphere, while two vegetated sites did not consume atmospheric hydrogen, an unusual observation. Although maximum potential CO uptake rates were also comparable to values for Kilauea, the relationship between these rates and organic carbon contents of scoria or soil indicated that CO oxidizers were relatively more abundant in Miyake-jima deposits. Phylogenetic analyses based on the large sub-unit gene for carbon monoxide dehydrogenase (coxL) indicated that many novel lineages were present on Miyake-jima, that CO-oxidizing Proteobacteria were prevalent in vegetated sites and that community structure appeared to vary more than composition among sites.

Tumor-Associated Macrophages Are Predominant Carriers of Cyclodextrin-Based Nanoparticles into Gliomas

PubMed Central

Alizadeh, Darya; Zhang, Leying; Hwang, Jungyeon; Schluep, Thomas; Badie, Behnam

2009-01-01

The goal of this study was to evaluate the mechanism of cyclodextrin-based nanoparticle (CDP-NP) uptake into a murine glioma model. Using mixed in vitro culture systems, we demonstrated that CDP-NP was preferentially taken up by BV2 and N9 microglia (MG) cells as compared to GL261 glioma cells. Fluorescent microscopy and flow cytometry analysis of intracranial (i.c.) GL261 gliomas confirmed these findings and demonstrated a predominant CDP-NP uptake by macrophages (MP) and MG within and around the tumor site. Interestingly, in mice bearing bilateral i.c. tumor, MG and MP carrying CDP-NP were able to migrate to the contralateral tumors. In conclusion, these studies better characterize the cellular distribution of CDP-NP in i.c. tumors and demonstrate that MP and MG could potentially be used as nanoparticle drug carriers into malignant brain tumors. PMID:19836468

Chemical Carcinogen-Induced Changes in tRNA Metabolism in Human Cells

DTIC Science & Technology

1984-11-20

uptake Chart 7 by POD was not affected by concurrent treatment with 0.1 mM quercetin (Chart 7). Epidermal growth factor (100 nM) also had no affect on...Therefore, we examined the affect on queuine uptake of quercetin , a flavanoid inhibitor of protein kinase C which binds to a site separate from the...phorbol ester binding site (12). Quercetin did not relieve the POO-effected inhibition of rQT3 uptake.. Although some residual activity of membrane bound

Trivalent chromium removal from aqueous solutions by a sol–gel synthesized silica adsorbent functionalized with sulphonic acid groups

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gomez-Gonzalez, Sergio Efrain; Carbajal-Arizaga, Gregorio Guadalupe; Manriquez-Gonzalez, Ricardo

Highlights: • Corpuscular sulphonic acid-functionalized silica holds improved uptake of chromium. • Mesopores on adsorbent facilitate (CH{sub 3}COO){sub 2}Cr{sup +} ion uptake on sulphonate sites. • Formation of chromium acetate sulphonate complex proposed from XPS results. • Fixed bed chromium uptake results suggest potential industrial use. - Abstract: A high capacity hybrid silica adsorbent was synthesized via sol–gel processing with sulphonic acid groups as trivalent chromium complex ions chelators from aqueous solutions. The synthesis included co-condensation of tetraethoxysilane (TEOS) with 3-(mercaptopropyl)trimethoxysilane (MPS), and oxidation of thiol to sulphonic acid groups. Chromium uptake kinetic, batch and fixed-bed experiments were performed tomore » assess the removal of this metal from aqueous solutions. {sup 13}C, {sup 29}Si CPMAS NMR, FTIR, XPS were used to characterize the adsorbent structure and the nature of chromium complexes on the adsorbent surface. Chromium maximum uptake was obtained at pH 3 (72.8 mg/g). Elemental analysis results showed ligand density of 1.48 mmol sulphonic groups/g. About 407 mL of Cr(III) solution (311 mg/L) were treated to breakthrough point reaching ≤0.06 mg/L at the effluent. These results comply with USEPA regulation for chromium concentration in drinking water (≤0.1 mg/L). The adsorbent shows potential to be used in chromium separations to the industrial level.« less

A top-down approach of surface carbonyl sulfide exchange by a Mediterranean oak forest ecosystem in southern France

NASA Astrophysics Data System (ADS)

Belviso, Sauveur; Reiter, Ilja Marco; Loubet, Benjamin; Gros, Valérie; Lathière, Juliette; Montagne, David; Delmotte, Marc; Ramonet, Michel; Kalogridis, Cerise; Lebegue, Benjamin; Bonnaire, Nicolas; Kazan, Victor; Gauquelin, Thierry; Fernandez, Catherine; Genty, Bernard

2016-12-01

The role that soil, foliage, and atmospheric dynamics have on surface carbonyl sulfide (OCS) exchange in a Mediterranean forest ecosystem in southern France (the Oak Observatory at the Observatoire de Haute Provence, O3HP) was investigated in June of 2012 and 2013 with essentially a top-down approach. Atmospheric data suggest that the site is appropriate for estimating gross primary production (GPP) directly from eddy covariance measurements of OCS fluxes, but it is less adequate for scaling net ecosystem exchange (NEE) to GPP from observations of vertical gradients of OCS relative to CO2 during the daytime. Firstly, OCS and carbon dioxide (CO2) diurnal variations and vertical gradients show no net exchange of OCS at night when the carbon fluxes are dominated by ecosystem respiration. This contrasts with other oak woodland ecosystems of a Mediterranean climate, where nocturnal uptake of OCS by soil and/or vegetation has been observed. Since temperature, water, and organic carbon content of soil at the O3HP should favor the uptake of OCS, the lack of nocturnal net uptake would indicate that its gross consumption in soil is compensated for by emission processes that remain to be characterized. Secondly, the uptake of OCS during the photosynthetic period was characterized in two different ways. We measured ozone (O3) deposition velocities and estimated the partitioning of O3 deposition between stomatal and non-stomatal pathways before the start of a joint survey of OCS and O3 surface concentrations. We observed an increasing trend in the relative importance of the stomatal pathway during the morning hours and synchronous steep drops of mixing ratios of OCS (amplitude in the range of 60-100 ppt) and O3 (amplitude in the range of 15-30 ppb) after sunrise and before the break up of the nocturnal boundary layer. The uptake of OCS by plants was also characterized from vertical profiles. However, the time window for calculation of the ecosystem relative uptake (ERU) of OCS, which is a useful tool for partitioning measured NEE, was limited in June 2012 to a few hours after midday. This was due to the disruption of the vertical distribution of OCS by entrainment of OCS rich tropospheric air in the morning and because the vertical gradient of CO2 reverses when it is still light. Moreover, polluted air masses (up to 700 ppt of OCS) produced dramatic variation in atmospheric OCS / CO2 ratios during the daytime in June 2013, further reducing the time window for ERU calculation.

A Universal Isotherm Model to Capture Adsorption Uptake and Energy Distribution of Porous Heterogeneous Surface.

PubMed

Ng, Kim Choon; Burhan, Muhammad; Shahzad, Muhammad Wakil; Ismail, Azahar Bin

2017-09-06

The adsorbate-adsorbent thermodynamics are complex as it is influenced by the pore size distributions, surface heterogeneity and site energy distribution, as well as the adsorbate properties. Together, these parameters defined the adsorbate uptake forming the state diagrams, known as the adsorption isotherms, when the sorption site energy on the pore surfaces are favorable. The available adsorption models for describing the vapor uptake or isotherms, hitherto, are individually defined to correlate to a certain type of isotherm patterns. There is yet a universal approach in developing these isotherm models. In this paper, we demonstrate that the characteristics of all sorption isotherm types can be succinctly unified by a revised Langmuir model when merged with the concepts of Homotattic Patch Approximation (HPA) and the availability of multiple sets of site energy accompanied by their respective fractional probability factors. The total uptake (q/q*) at assorted pressure ratios (P/P s ) are inextricably traced to the manner the site energies are spread, either naturally or engineered by scientists, over and across the heterogeneous surfaces. An insight to the porous heterogeneous surface characteristics, in terms of adsorption site availability has been presented, describing the unique behavior of each isotherm type.

Extrapulmonary sites of radiogallium accumulation in sarcoidosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sulavik, S.B.; Palestro, C.J.; Spencer, R.P.

1990-12-01

In an effort to detect extrapulmonary sites of radiogallium accumulation in cases of sarcoidosis, 145 separate Ga-67 citrate studies of 114 patients with biopsy-proven sarcoidosis were examined. The most characteristic extrapulmonary radiogallium uptake pattern was the panda sign in 47 patients (41%). The most common site of prominent extrapulmonary radiogallium uptake was the lacrimal glands in 101 patients (88%). Second most common was activity in one or more superficial lymph node regions such as the cervical, axillary, femoral, or inguinal in 19 patients (17%). Other extrapulmonary sites included breast uptake in 6 out of 80 women (8%), prominent splenic andmore » nasal uptake in 9 (8%) patients, periportal accumulation in 7 (6%), and cutaneous/subcutaneous activity in 4 (4%). Because many of these individuals were receiving corticosteroids, the natural (untreated) prevalence of extrapulmonary findings may be even higher. Although the sensitivity and specificity of extrapulmonary radiogallium accumulation has still to be determined, many of the sites may be accessible to biopsy both for diagnostic purposes and to follow the effects of medications. It is therefore suggested that whole-body imaging be performed when radiogallium is administered to patients with suspected or known sarcoidosis.« less

Anorectic activities of serotonin uptake inhibitors: correlation with their potencies at inhibiting serotonin uptake in vivo and /sup 3/H-mazindol binding in vitro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Angel, I.; Taranger, M.A.; Claustre, Y.

1988-01-01

The mechanism of anorectic action of several serotonin uptake inhibitors was investigated by comparing their anorectic potencies with several biochemical and pharmacological properties and in reference to the novel compound SL 81.0385. The anorectic effect of the potent serotonin uptake inhibitor SL 81.0385 was potentiated by pretreatment with 5-hydroxytryptophan and blocked by the serotonin receptor antagonist metergoline. A good correlation was obtained between the ED/sub 50/ values of anorectic action and the ED/sub 50/ values of serotonin uptake inhibition in vivo (but not in vitro) for several specific serotonin uptake inhibitors. Most of the drugs tested displaced (/sup 3/H)-mazindol frommore » its binding to the anorectic recognition site in the hypothalamus, except the pro-drug zimelidine which was inactive. Excluding zimelidine, a good correlation was obtained between the affinities of these drugs for (/sup 3/H)-mazindol binding and their anorectic action indicating that their anorectic activity may be associated with an effect mediated through this site. Taken together these results suggest that the anorectic action of serotonin uptake inhibitors is directly associated to their ability to inhibit serotonin uptake and thus increasing the synaptic levels of serotonin. The interactions of these drugs with the anorectic recognition site labelled with (/sup 3/H)-mazindol is discussed in connection with the serotonergic regulation of carbohydrate intake.« less

Tryptophanyl-tRNA synthetase mediates high-affinity tryptophan uptake into human cells.

PubMed

Miyanokoshi, Miki; Yokosawa, Takumi; Wakasugi, Keisuke

2018-06-01

The tryptophan (Trp) transport system has a high affinity and selectivity toward Trp, and has been reported to exist in both human and mouse macrophages. Although this system is highly expressed in interferon-γ (IFN-γ)-treated cells and indoleamine 2,3-dioxygenase 1 (IDO1)-expressing cells, its identity remains incompletely understood. Tryptophanyl-tRNA synthetase (TrpRS) is also highly expressed in IFN-γ-treated cells and also has high affinity and selectivity for Trp. Here, we investigated the effects of human TrpRS expression on Trp uptake into IFN-γ-treated human THP-1 monocytes or HeLa cells. Inhibition of human TrpRS expression by TrpRS-specific siRNAs decreased and overexpression of TrpRS increased Trp uptake into the cells. Of note, the TrpRS-mediated uptake system had more than hundred-fold higher affinity for Trp than the known System L amino acid transporter, promoted uptake of low Trp concentrations, and had very high Trp selectivity. Moreover, site-directed mutagenesis experiments indicated that Trp- and ATP-binding sites, but not tRNA-binding sites, in TrpRS are essential for TrpRS-mediated Trp uptake into the human cells. We further demonstrate that the addition of purified TrpRS to cell culture medium increases Trp uptake into cells. Taken together, our results reveal that TrpRS plays an important role in high-affinity Trp uptake into human cells. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Plant uptake of 238U, 235U, 232Th, 226Ra, 210Pb and 40K from a coal ash and slag disposal site and control soil under field conditions: A preliminary study.

PubMed

Skoko, Božena; Marović, Gordana; Babić, Dinko; Šoštarić, Marko; Jukić, Mirela

2017-06-01

The aim of this study was to investigate the uptake of 238 U, 235 U, 232 Th, 226 Ra, 210 Pb and 40 K by plants that grow on a coal ash and slag disposal site known for its higher content of naturally occurring radionuclides. Plant species that were sampled are common for the Mediterranean flora and can be divided as follows: grasses & herbs, shrubs and trees. To compare the activity concentrations and the resultant concentration ratios of the disposal site with those in natural conditions, we used control data specific for the research area, obtained for plants growing on untreated natural soil. Radionuclide activity concentrations were determined by high resolution gamma-ray spectrometry. Media parameters (pH, electrical conductivity and organic matter content) were also analysed. We confirmed significantly higher activity concentrations of 238 U, 235 U, 226 Ra and 210 Pb in ash and slag compared to control soil. However, a significant increase in the radionuclide activity concentration in the disposal site's vegetation was observed only for 226 Ra. On the contrary, a significantly smaller activity concentration of 40 K in ash and slag had no impact on its activity concentration in plant samples. The calculated plant uptake of 238 U, 235 U, 226 Ra and 210 Pb is significantly smaller in comparison with the uptake at the control site, while it is vice versa for 40 K. No significant difference was observed between the disposal site and the control site's plant uptake of 232 Th. These results can be the foundation for further radioecological assessment of this disposal site but also, globally, they can contribute to a better understanding of nature and long-term management of such disposal sites. Copyright © 2017 Elsevier Ltd. All rights reserved.

Light dependence of selenium uptake by phytoplankton and implications for predicting selenium incorporation into food webs

USGS Publications Warehouse

Baines, S.B.; Fisher, N.S.; Doblin, M.A.; Cutter, G.A.; Cutter, L.S.; Cole, B.

2004-01-01

The potentially toxic element selenium is first concentrated from solution to a large but highly variable degree by algae and bacteria before being passed on to consumers. The large loads of abiotic and detrital suspended particles often present in rivers and estuaries may obscure spatial and temporal patterns in Se concentrations at the base of the food web. We used radiotracers to estimate uptake of both selenite (Se(IV)) and C by intact plankton communities at two sites in the Sacramento/San Joaquin River Delta. Our goals were to determine (1) whether C and Se(IV) uptake were coupled, (2) the role of bacteria in Se(IV) uptake, and (3) the Se:C uptake ratio of newly produced organic material. Se(IV) uptake, like C uptake, was strongly related to irradiance. The shapes of both relationships were very similar except that at least 42-56% of Se(IV) uptake occurred in the dark, whereas C uptake in the dark was negligible. Of this dark Se(IV) uptake, 34-67% occurred in the 0.2-1.0-??m size fraction, indicating significant uptake by bacteria. In addition to dark uptake, total Se(IV) uptake consisted of a light-driven component that was in fixed proportion to C uptake. Our estimates of daily areal Se(IV):C uptake ratios agreed very well with particulate Se:C measured at a site dominated by phytoplankton biomass. Estimates of bacterial Se:C were 2.4-13 times higher than for the phytoplankton, suggesting that bacteriovores may be exposed to higher dietary Se concentrations than herbivores.

Variable effects of plant colonization on black slate uptake into microbial PLFAs

NASA Astrophysics Data System (ADS)

Seifert, Anne-Gret; Trumbore, Susan; Xu, Xiaomei; Zhang, Dachung; Gleixner, Gerd

2013-04-01

Microbial degradation of carbon derived from black shale and slate has been shown in vitro. However, in natural settings where other labile carbon sources are likely to exist, this has not been previously demonstrated. We investigated the uptake of ancient carbon derived from slate weathering and from recently photosynthesised organic matter by different groups of microorganisms. Therefore we isolated microbial biomarkers (phospholipid fatty acids, PLFAs) from black slates collected at a chronosequence of waste piles which differed in age and vegetation cover. We quantified the amount of PLFAs and performed stable isotope and radiocarbon measurements on individual or grouped PLFAs to quantify the fraction of slate derived carbon. We used black slate from a pile heaped in the 1950s with either uncovered black slate material (bare site) or material slightly colonized by small plants (greened site) and from a forested leaching pile (forested site) used for alum-mining in the 19th century. Colonization by plants influenced the amount and composition of the microbial community. Greater amounts of PLFAs (5410 ng PLFA/g dw) were extracted from slate sampled at the forested site as opposed to the bare site (960 ng PLFAs/g dw) or the greened (annual grasses and mosses) rock waste pile (1050 ng PLFAs/g dw). We found the highest proportion of PLFAs representing Gram-negative bacteria on the forested site and the highest proportion of PLFAs representing Gram-positive bacteria on the bare site. The fungal PLFA was most abundant at the greened site. Sites with less plant colonization (bare and greened site) tended to have more depleted δ13C values compared to the forested site. Radiocarbon measurements on PLFAs indicated that fungi and Gram-positive bacteria were best adapted to black slate carbon uptake. In the fungal PLFA (combined bare and greened waste pile sample) and in PLFAs of Gram-positive bacteria (greened site) we measured 39.7% and 28.9% ancient carbon uptake, respectively. Our results prove that black slate degradation followed by carbon uptake takes place in situ. Results imply that plant colonization might additionally affect this process. Slight colonization with few plants increased slate derived carbon uptake in PLFAs of Gram-positive bacteria. Evidently, Gram-positive bacteria represented by specific PLFAs from the greened site held more ancient carbon than from the bare site. In contrast, no black slate derived carbon was used by microorganisms at the forested site with 2-3 times greater carbon content. Results suggest that the use of ancient slate derived carbon dominates mainly in early stages of microbial colonization of surfaces and that with increasing ecosystem development recycling of plant derived carbon dominates.

Optimizing the mobility of residents with dementia: a pilot study promoting healthcare aide uptake of a simple mobility innovation in diverse nursing home settings.

PubMed

Slaughter, Susan E; Estabrooks, Carole A

2013-10-18

Almost 90 percent of nursing home residents have some type of mobility limitation. Many spend most of their waking hours lying in bed or sitting. Such inactivity can negatively affect residents' health and general well-being. This pilot study aimed to assess (1) the effect of the sit-to-stand activity on mobility outcomes of nursing home residents, (2) the effect of an audit-and-feedback intervention on uptake of the sit-to-stand activity by healthcare aides, and (3) the contextual factors influencing uptake of the sit-to-stand activity by healthcare aides. This quasi-experimental pilot study was conducted in two nursing homes in western Canada. Twenty-six residents with dementia completed the sit-to-stand activity with 56 healthcare aides during daily care; separately, 71 healthcare aides completed a research use and context survey. Preliminary mobility feedback was presented to healthcare aides in one site. Resident mobility was measured using the 30-second sit-to-stand test. Healthcare aide uptake of the activity was measured using documentation flowsheets and a survey-based measure. Context was measured using the Alberta Context Tool. Mobility and uptake outcomes were analyzed over time and by site with analysis of covariance. Spearman and Pearson correlations were used to correlate context data with research use. Residents who more frequently completed the sit-to-stand activity were more likely to maintain or improve mobility compared with those who completed it less frequently (F=4.46; p=0.046, after adjustment for age). Uptake for one site was significantly different from the other (t-score=2.67; p=0.01, after adjustment for resident covariates). The audit-and-feedback intervention was associated with increased uptake of the activity from pre-intervention to post-intervention (t-score=-2.48; p=0.02). More context domains correlated significantly with aides' use of conceptual research and information sources in one site than the other. The sit-to-stand activity is a promising means to maintain or improve transfer ability of nursing home residents with dementia. In the nursing home with initially weak uptake, strengthened uptake followed an audit-and-feedback intervention. Activity participation was higher in the site with stronger correlations between context and measured research use. Results are sufficiently promising to warrant proceeding with a full clinical trial.

A computational prediction of structure and function of novel homologue of Arabidopsis thaliana Vps51/Vps67 subunit in Corchorus olitorius.

PubMed

Zaman, Aubhishek; Fancy, Nurun Nahar

2012-12-01

Vps mediated vesicular transport is important for transferring macromolecules trapped inside a vesicle. Although highly abundant, Vps shows tremendous sequence variation among diverse array of species. However, this difference in sequence, which seems to also translate into substantial functional variation, is hardly characterized in Corchorus spp. Here, our computational study investigates structural and functional features of one of the Vps subunit namely Vps51/Vps67 in C. olitorius. Broad scale structural characterization revealed novel information about the overall Vps structure and binding sites. Moreover, functional analyses indicate interaction partners which were unexplored to date. Since membrane trafficking is essentially associated with nutrient uptake and chemical de-toxification, characterization of the Vps subunit can well provide us with better insight into important agronomic traits such as stress response, immune response and phytoremediation capacity.

Sphagnum Mosses - Masters of Efficient N-Uptake while Avoiding Intoxication

PubMed Central

Fritz, Christian; Lamers, Leon P. M.; Riaz, Muhammad; van den Berg, Leon J. L.; Elzenga, Theo J. T. M.

2014-01-01

Peat forming Sphagnum mosses are able to prevent the dominance of vascular plants under ombrotrophic conditions by efficiently scavenging atmospherically deposited nitrogen (N). N-uptake kinetics of these mosses are therefore expected to play a key role in differential N availability, plant competition, and carbon sequestration in Sphagnum peatlands. The interacting effects of rain N concentration and exposure time on moss N-uptake rates are, however, poorly understood. We investigated the effects of N-concentration (1, 5, 10, 50, 100, 500 µM), N-form (15N - ammonium or nitrate) and exposure time (0.5, 2, 72 h) on uptake kinetics for Sphagnum magellanicum from a pristine bog in Patagonia (Argentina) and from a Dutch bog exposed to decades of N-pollution. Uptake rates for ammonium were higher than for nitrate, and N-binding at adsorption sites was negligible. During the first 0.5 h, N-uptake followed saturation kinetics revealing a high affinity (Km 3.5–6.5 µM). Ammonium was taken up 8 times faster than nitrate, whereas over 72 hours this was only 2 times. Uptake rates decreased drastically with increasing exposure times, which implies that many short-term N-uptake experiments in literature may well have overestimated long-term uptake rates and ecosystem retention. Sphagnum from the polluted site (i.e. long-term N exposure) showed lower uptake rates than mosses from the pristine site, indicating an adaptive response. Sphagnum therefore appears to be highly efficient in using short N pulses (e.g. rainfall in pristine areas). This strategy has important ecological and evolutionary implications: at high N input rates, the risk of N-toxicity seems to be reduced by lower uptake rates of Sphagnum, at the expense of its long-term filter capacity and related competitive advantage over vascular plants. As shown by our conceptual model, interacting effects of N-deposition and climate change (changes in rainfall) will seriously alter the functioning of Sphagnum peatlands. PMID:24416125

Sphagnum mosses--masters of efficient N-uptake while avoiding intoxication.

PubMed

Fritz, Christian; Lamers, Leon P M; Riaz, Muhammad; van den Berg, Leon J L; Elzenga, Theo J T M

2014-01-01

Peat forming Sphagnum mosses are able to prevent the dominance of vascular plants under ombrotrophic conditions by efficiently scavenging atmospherically deposited nitrogen (N). N-uptake kinetics of these mosses are therefore expected to play a key role in differential N availability, plant competition, and carbon sequestration in Sphagnum peatlands. The interacting effects of rain N concentration and exposure time on moss N-uptake rates are, however, poorly understood. We investigated the effects of N-concentration (1, 5, 10, 50, 100, 500 µM), N-form ((15)N-ammonium or nitrate) and exposure time (0.5, 2, 72 h) on uptake kinetics for Sphagnum magellanicum from a pristine bog in Patagonia (Argentina) and from a Dutch bog exposed to decades of N-pollution. Uptake rates for ammonium were higher than for nitrate, and N-binding at adsorption sites was negligible. During the first 0.5 h, N-uptake followed saturation kinetics revealing a high affinity (Km 3.5-6.5 µM). Ammonium was taken up 8 times faster than nitrate, whereas over 72 hours this was only 2 times. Uptake rates decreased drastically with increasing exposure times, which implies that many short-term N-uptake experiments in literature may well have overestimated long-term uptake rates and ecosystem retention. Sphagnum from the polluted site (i.e. long-term N exposure) showed lower uptake rates than mosses from the pristine site, indicating an adaptive response. Sphagnum therefore appears to be highly efficient in using short N pulses (e.g. rainfall in pristine areas). This strategy has important ecological and evolutionary implications: at high N input rates, the risk of N-toxicity seems to be reduced by lower uptake rates of Sphagnum, at the expense of its long-term filter capacity and related competitive advantage over vascular plants. As shown by our conceptual model, interacting effects of N-deposition and climate change (changes in rainfall) will seriously alter the functioning of Sphagnum peatlands.

Uptake of lactosylated low-density lipoprotein by galactose-specific receptors in rat liver.

PubMed

Bijsterbosch, M K; Van Berkel, T J

1990-08-15

The liver contains two types of galactose receptors, specific for Kupffer and parenchymal cells respectively. These receptors are only expressed in the liver, and therefore are attractive targets for the specific delivery of drugs. We provided low-density lipoprotein (LDL), a particle with a diameter of 23 nm in which a variety of drugs can be incorporated, with terminal galactose residues by lactosylation. Radioiodinated LDL, lactosylated to various extents (60-400 mol of lactose/ mol of LDL), was injected into rats. The plasma clearance and hepatic uptake of radioactivity were correlated with the extent of lactosylation. Highly lactosylated LDL (greater than 300 lactose/LDL) is completely cleared from the blood by liver within 10 min. Pre-injection with N-acetylgalactosamine blocks liver uptake, which indicates that the hepatic recognition sites are galactose-specific. The hepatic uptake occurs mainly by parenchymal and Kupffer cells. At a low degree of lactosylation, approx. 60 lactose/LDL, the specific uptake (ng/mg of cell protein) is 28 times higher in Kupffer cells than in parenchymal cells. However, because of their much larger mass, parenchymal cells are the main site of uptake. At high degrees of lactosylation (greater than 300 lactose/LDL), the specific uptake in Kupffer cells is 70-95 times that in parenchymal cells. Under these conditions, Kupffer cells are, despite their much smaller mass, the main site of uptake. Thus not only the size but also the surface density of galactose on lactosylated LDL is important for the balance of uptake between Kupffer and parenchymal cells. This knowledge should allow us to design particulate galactose-bearing carriers for the rapid transport of various drugs to either parenchymal cells or Kupffer cells.

Quantitative PET/CT scanner performance characterization based upon the society of nuclear medicine and molecular imaging clinical trials network oncology clinical simulator phantom.

PubMed

Sunderland, John J; Christian, Paul E

2015-01-01

The Clinical Trials Network (CTN) of the Society of Nuclear Medicine and Molecular Imaging (SNMMI) operates a PET/CT phantom imaging program using the CTN's oncology clinical simulator phantom, designed to validate scanners at sites that wish to participate in oncology clinical trials. Since its inception in 2008, the CTN has collected 406 well-characterized phantom datasets from 237 scanners at 170 imaging sites covering the spectrum of commercially available PET/CT systems. The combined and collated phantom data describe a global profile of quantitative performance and variability of PET/CT data used in both clinical practice and clinical trials. Individual sites filled and imaged the CTN oncology PET phantom according to detailed instructions. Standard clinical reconstructions were requested and submitted. The phantom itself contains uniform regions suitable for scanner calibration assessment, lung fields, and 6 hot spheric lesions with diameters ranging from 7 to 20 mm at a 4:1 contrast ratio with primary background. The CTN Phantom Imaging Core evaluated the quality of the phantom fill and imaging and measured background standardized uptake values to assess scanner calibration and maximum standardized uptake values of all 6 lesions to review quantitative performance. Scanner make-and-model-specific measurements were pooled and then subdivided by reconstruction to create scanner-specific quantitative profiles. Different makes and models of scanners predictably demonstrated different quantitative performance profiles including, in some cases, small calibration bias. Differences in site-specific reconstruction parameters increased the quantitative variability among similar scanners, with postreconstruction smoothing filters being the most influential parameter. Quantitative assessment of this intrascanner variability over this large collection of phantom data gives, for the first time, estimates of reconstruction variance introduced into trials from allowing trial sites to use their preferred reconstruction methodologies. Predictably, time-of-flight-enabled scanners exhibited less size-based partial-volume bias than non-time-of-flight scanners. The CTN scanner validation experience over the past 5 y has generated a rich, well-curated phantom dataset from which PET/CT make-and-model and reconstruction-dependent quantitative behaviors were characterized for the purposes of understanding and estimating scanner-based variances in clinical trials. These results should make it possible to identify and recommend make-and-model-specific reconstruction strategies to minimize measurement variability in cancer clinical trials. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Probing functional groups at the gas-aerosol interface using heterogeneous titration reactions: a tool for predicting aerosol health effects?

PubMed

Setyan, Ari; Sauvain, Jean-Jacques; Guillemin, Michel; Riediker, Michael; Demirdjian, Benjamin; Rossi, Michel J

2010-12-17

The complex chemical and physical nature of combustion and secondary organic aerosols (SOAs) in general precludes the complete characterization of both bulk and interfacial components. The bulk composition reveals the history of the growth process and therefore the source region, whereas the interface controls--to a large extent--the interaction with gases, biological membranes, and solid supports. We summarize the development of a soft interrogation technique, using heterogeneous chemistry, for the interfacial functional groups of selected probe gases [N(CH(3))(3), NH(2)OH, CF(3)COOH, HCl, O(3), NO(2)] of different reactivity. The technique reveals the identity and density of surface functional groups. Examples include acidic and basic sites, olefinic and polycyclic aromatic hydrocarbon (PAH) sites, and partially and completely oxidized surface sites. We report on the surface composition and oxidation states of laboratory-generated aerosols and of aerosols sampled in several bus depots. In the latter case, the biomarker 8-hydroxy-2'-deoxyguanosine, signaling oxidative stress caused by aerosol exposure, was isolated. The increase in biomarker levels over a working day is correlated with the surface density N(i)(O3) of olefinic and/or PAH sites obtained from O(3) uptakes as well as with the initial uptake coefficient, γ(0), of five probe gases used in the field. This correlation with γ(0) suggests the idea of competing pathways occurring at the interface of the aerosol particles between the generation of reactive oxygen species (ROS) responsible for oxidative stress and cellular antioxidants.

Radiological bioconcentration factors for aquatic, terrestrial, and wetland ecosystems at the Savannah River Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cummins, C.L.

As a result of operations at the Savannah River Site (SRS), over 50 radionuclides have been released to the atmosphere and to onsite streams and seepage basins. Now, many of these radionuclides are available to aquatic and/or terrestrial organisms for uptake and cycling through the food chain. Knowledge about the uptake and cycling of these radionuclides is now crucial in evaluating waste management and clean-up alternatives for the site. Numerous studies have been conducted at the SRS over the past forty years to study the uptake and distribution of radionuclides in the Savannah River Site environment. In many instances, bioconcentrationmore » factors have been calculated to quantify the uptake of a radionuclide by an organism from the surrounding medium (i.e., soil or water). In the past, it has been common practice to use bioconcentration factors from the literature because site-specific data were not readily available. However, because of the variability of bioconcentration factors due to experimental or environmental conditions, site-specific data should be used when available. This report compiles and summarizes site-specific bioconcentration factors for selected radionuclides released at the Savannah River Site (SRS). An extensive literature search yielded site-specific bioconcentration factors for cesium, strontium, cobalt, plutonium, americium, curium, and tritium. These eight radionuclides have been the primary radionuclides studied at SRS because of their long half lives or because they are major contributors to radiological dose from exposure. For most radionuclides, it was determined that the site-specific bioconcentration factors were higher than those reported in literature. This report also summarizes some conditions that affect radionuclide bioavailability to and bioconcentration by aquatic and terrestrial organisms.« less

Action of insecticidal N-alkylamides at site 2 of the voltage-sensitive sodium channel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ottea, J.A.; Payne, G.T.; Soderlund, D.M.

1990-08-01

Nine synthetic N-alkylamides were examined as inhibitors of the specific binding of ({sup 3}H)batrachotoxinin A 20{alpha}-benzoate (({sup 3}H)BTX-B) to sodium channels and as activators of sodium uptake in mouse brain synaptoneurosomes. In the presence of scorpion (Leiurus quinquestriatus) venom, the six insecticidal analogues were active as both inhibitors of ({sup 3}H)BTX-B binding and stimulators of sodium uptake. These findings are consistent with an action of these compounds at the alkaloid activator recognition site (site 2) of the voltage-sensitive sodium channel. The three noninsecticidal N-alkylamides also inhibited ({sup 3}H)BTX-B binding but were ineffective as activators of sodium uptake. Concentration-response studies revealedmore » that some of the insecticidal amides also enhanced sodium uptake through a second, high-affinity interaction that does not involve site 2, but this secondary effect does not appear to be correlated with insecticidal activity. The activities of N-alkylamides as sodium channel activators were influenced by the length of the alkenyl chain and the location of unsaturation within the molecule. These results further define the actions of N-alkylamides on sodium channels and illustrate the significance of the multiple binding domains of the sodium channel as target sites for insect control agents.« less

Strategies for sustainable woodland on contaminated soils.

PubMed

Dickinson, N M

2000-07-01

Extensive in situ reclamation treatment technologies are appropriate for a large proportion of contaminated land in place of total removal or complete containment of soil. In this paper, initial results are presented of site descriptions, tree survival and metal uptake patterns from two field planting trials on a highly industrially contaminated site adjacent to a metal refinery and on old sanitary landfill sites. Survival rate was high in both trials but factors besides heavy metals were particularly significant. Uptake patterns of metals into foliage and woody tissues were variable, with substantial uptake in some species and clones supporting the findings of earlier pot experiments. It is argued that there is sufficient evidence to consider the use of trees in reclamation as part of a realistic, integrated, low-cost, ecologically-sound and sustainable reclamation strategy for contaminated land. This is an opportunity to bring a large number of brownfield sites into productive use, which otherwise would be prohibitively expensive to restore.

Highly porous organic polymers bearing tertiary amine group and their exceptionally high CO{sub 2} uptake capacities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gomes, Ruth; Bhaumik, Asim, E-mail: msab@iacs.res.in

2015-02-15

We report a very simple and unique strategy for synthesis of a tertiary amine functionalized high surface area porous organic polymer (POP) PDVTA-1 through the co-polymerization of monomers divinylbenzene (DVB) and triallylamine (TAA) under solvothermal reaction conditions. Two different PDVTA-1 samples have been synthesized by varying the molar ratio of the monomers. The porous polymeric materials have been thoroughly characterized by solid state {sup 13}C CP MAS-NMR, FT-IR and UV–vis spectroscopy, N{sub 2} sorption, HR TEM and FE SEM to understand its chemical environment, nanostructure, bonding, morphology and related surface properties. PDVTA-1 with higher amine content (DVB/TAA=4.0) showed exceptionally highmore » CO{sub 2} uptake capacity of 85.8 wt% (19.5 mmol g{sup −1}) at 273 K and 43.69 wt% (9.93 mmol g{sup −1}) at 298 K under 3 bar pressure, whereas relatively low amine loaded material (DVB/TAA=7.0) shows uptake capacity of 59.2 wt% (13.45 mmol g{sup −1}) at 273 K and 34.36 wt% (7.81 mmol g{sup −1}) at 298 K. Highly porous nanostructure together with very high surface area and basicity at the surface due to the presence of abundant basic tertiary amine N-sites in the framework of PDVTA-1 could be responsible for very high CO{sub 2} adsorption. - Graphical abstract: Exceptionally high CO2 uptake (85.8 wt % at 273 K) has been observed over a high surface area porous organic polymer PDVTA-1 synthesized through copolymerization of divinylbenzene and triallyl amine. - Highlights: • Designing the synthesis of a new N-rich cross-linked porous organic polymer PDVTA-1. • PDVTA-1 showed mesoporosity with very high surface area of 903 m{sup 2} g{sup −1}. • High surface area and presence of basic sites facilitates the CO{sub 2} uptake. • PDVTA-1 showed exceptionally high CO{sub 2} adsorption capacity of 85.8 wt% at 273 K, 3 bar pressure.« less

Association of vascular fluoride uptake with vascular calcification and coronary artery disease.

PubMed

Li, Yuxin; Berenji, Gholam R; Shaba, Wisam F; Tafti, Bashir; Yevdayev, Ella; Dadparvar, Simin

2012-01-01

The feasibility of a fluoride positron emission tomography/computed tomography (PET/CT) scan for imaging atherosclerosis has not been well documented. The purpose of this study was to assess fluoride uptake of vascular calcification in various major arteries, including coronary arteries. We retrospectively reviewed the imaging data and cardiovascular history of 61 patients who received whole-body sodium [¹⁸F]fluoride PET/CT studies at our institution from 2009 to 2010. Fluoride uptake and calcification in major arteries, including coronary arteries, were analyzed by both visual assessment and standardized uptake value measurement. Fluoride uptake in vascular walls was demonstrated in 361 sites of 54 (96%) patients, whereas calcification was observed in 317 sites of 49 (88%) patients. Significant correlation between fluoride uptake and calcification was observed in most of the arterial walls, except in those of the abdominal aorta. Fluoride uptake in coronary arteries was demonstrated in 28 (46%) patients and coronary calcifications were observed in 34 (56%) patients. There was significant correlation between history of cardiovascular events and presence of fluoride uptake in coronary arteries. The coronary fluoride uptake value in patients with cardiovascular events was significantly higher than in patients without cardiovascular events. sodium [¹⁸F]fluoride PET/CT might be useful in the evaluation of the atherosclerotic process in major arteries, including coronary arteries. An increased fluoride uptake in coronary arteries may be associated with an increased cardiovascular risk.

Beta-test Results for an HPV Information Web site: GoHealthyGirls.org – Increasing HPV Vaccine Uptake in the United States

PubMed Central

Nodulman, Jessica A.; Kong, Alberta S.; Wheeler, Cosette M.; Buller, David B.; Woodall, W. Gill

2014-01-01

A web site, GoHealthyGirls, was developed to educate and inform parents and their adolescent daughters about human papillomavirus (HPV) and HPV vaccines. This article provides an overview of web site development and content followed by the results of a beta-test of the web site. 63 New Mexican parents of adolescent girls tested the site. Results indicated that GoHealthyGirls was a functioning and appealing web site. During this brief educational intervention, findings suggest that the web site has the potential to increase HPV vaccine uptake. This research supports the Internet as a valuable channel to disseminate health education and information to diverse populations. PMID:25221442

Characterization of the Commercially-Available Fluorescent Chloroquine-BODIPY Conjugate, LynxTag-CQGREEN, as a Marker for Chloroquine Resistance and Uptake in a 96-Well Plate Assay

PubMed Central

Chan, Kitti W. K.; Choy, Kit-Ying; Rénia, Laurent; Russell, Bruce; Lear, Martin J.; Nosten, François H.; Tan, Kevin S. W.; Chow, Larry M. C.

2014-01-01

Chloroquine was a cheap, extremely effective drug against Plasmodium falciparum until resistance arose. One approach to reversing resistance is the inhibition of chloroquine efflux from its site of action, the parasite digestive vacuole. Chloroquine accumulation studies have traditionally relied on radiolabelled chloroquine, which poses several challenges. There is a need for development of a safe and biologically relevant substitute. We report here a commercially-available green fluorescent chloroquine-BODIPY conjugate, LynxTag-CQGREEN, as a proxy for chloroquine accumulation. This compound localized to the digestive vacuole of the parasite as observed under confocal microscopy, and inhibited growth of chloroquine-sensitive strain 3D7 more extensively than in the resistant strains 7G8 and K1. Microplate reader measurements indicated suppression of LynxTag-CQGREEN efflux after pretreatment of parasites with known reversal agents. Microsomes carrying either sensitive- or resistant-type PfCRT were assayed for uptake; resistant-type PfCRT exhibited increased accumulation of LynxTag-CQGREEN, which was suppressed by pretreatment with known chemosensitizers. Eight laboratory strains and twelve clinical isolates were sequenced for PfCRT and Pgh1 haplotypes previously reported to contribute to drug resistance, and pfmdr1 copy number and chloroquine IC50s were determined. These data were compared with LynxTag-CQGREEN uptake/fluorescence by multiple linear regression to identify genetic correlates of uptake. Uptake of the compound correlated with the logIC50 of chloroquine and, more weakly, a mutation in Pgh1, F1226Y. PMID:25343249

Endogenous and exogenous control of ecosystem function: N cycling in headwater streams.

PubMed

Valett, H M; Thomas, S A; Mulholland, P J; Webster, J R; Dahm, C N; Fellows, C S; Crenshaw, C L; Peterson, C G

2008-12-01

Allochthonous inputs act as resource subsidies to many ecosystems, where they exert strong influences on metabolism and material cycling. At the same time, metabolic theory proposes endogenous thermal control independent of resource supply. To address the relative importance of exogenous and endogenous influences, we quantified spatial and temporal variation in ecosystem metabolism and nitrogen (N) uptake using seasonal releases of 15N as nitrate in six streams differing in riparian-stream interaction and metabolic character. Nitrate removal was quantified using a nutrient spiraling approach based on measurements of downstream decline in 15N flux. Respiration (R) and gross primary production (GPP) were measured with whole-stream diel oxygen budgets. Uptake and metabolism metrics were addressed as z scores relative to site means to assess temporal variation. In open-canopied streams, areal uptake (U; microg N x m(-2) x s(-1)) was closely related to GPP, metabolic rates increased with temperature, and R was accurately predicted by metabolic scaling relationships. In forested streams, N spiraling was not related to GPP; instead, uptake velocity (v(f); mm/s) was closely related to R. In contrast to open-canopied streams, N uptake and metabolic activity were negatively correlated to temperature and poorly described by scaling laws. We contend that streams differ along a gradient of exogenous and endogenous control that relates to the relative influences of resource subsidies and in-stream energetics as determinants of seasonal patterns of metabolism and N cycling. Our research suggests that temporal variation in the propagation of ecological influence between adjacent systems generates phases when ecosystems are alternatively characterized as endogenously and exogenously controlled.

Deletion of the Uracil Permease Gene Confers Cross-Resistance to 5-Fluorouracil and Azoles in Candida lusitaniae and Highlights Antagonistic Interaction between Fluorinated Nucleotides and Fluconazole

PubMed Central

Gabriel, Frédéric; Sabra, Ayman; El-Kirat-Chatel, Sofiane; Pujol, Sophie; Fitton-Ouhabi, Valérie; Brèthes, Daniel; Dementhon, Karine; Accoceberry, Isabelle

2014-01-01

We characterized two additional membrane transporters (Fur4p and Dal4p) of the nucleobase cation symporter 1 (NCS1) family involved in the uptake transport of pyrimidines and related molecules in the opportunistic pathogenic yeast Candida lusitaniae. Simple and multiple null mutants were constructed by gene deletion and genetic crosses. The function of each transporter was characterized by supplementation experiments, and the kinetic parameters of the uptake transport of uracil were measured using radiolabeled substrate. Fur4p specifically transports uracil and 5-fluorouracil. Dal4p is very close to Fur4p and transports allantoin (glyoxyldiureide). Deletion of the FUR4 gene confers resistance to 5-fluorouracil as well as cross-resistance to triazoles and imidazole antifungals when they are used simultaneously with 5-fluorouracil. However, the nucleobase transporters are not involved in azole uptake. Only fluorinated pyrimidines, not pyrimidines themselves, are able to promote cross-resistance to azoles by both the salvage and the de novo pathway of pyrimidine synthesis. A reinterpretation of the data previously obtained led us to show that subinhibitory doses of 5-fluorocytosine, 5-fluorouracil, and 5-fluorouridine also were able to trigger resistance to fluconazole in susceptible wild-type strains of C. lusitaniae and of different Candida species. Our results suggest that intracellular fluorinated nucleotides play a key role in azole resistance, either by preventing azoles from targeting the lanosterol 14-alpha-demethylase or its catalytic site or by acting as a molecular switch for the triggering of efflux transport. PMID:24867971

In vitro and in vivo pharmacokinetics and toxicity evaluation of curcumin incorporated titanium dioxide nanoparticles for biomedical applications.

PubMed

Sherin, Sainulabdeen; Sheeja, Sathyabhama; Sudha Devi, Rukhmini; Balachandran, Sreedharan; Soumya, Rema Sreenivasan; Abraham, Annie

2017-09-25

The present study deals with the preparation of stable Curcumin incorporated Titaniumdioxide Nanoparticles (CTNPs) by coprecipitation method for improving the bioavailability of curcumin and site specific drug delivery. The prepared nanoparticles were characterized by UV visible spectroscopy, FTIR, XRD, DLS, SEM and EDX. The characterization studies showed the interaction of curcumin to titanium dioxide nanoparticles. The average size of the prepared CTNPs was found to be ∼29 nm with zetapotential of-53.790 mV. In vivo and in vitro toxicological evaluations were carried out to determine the biological effect of CTNPs. In vitro parameters like cell viability, Lactate dehydrogenase (LDH) Assay, Neutral red uptake (NRU) assay and uptake of curcumin from CTNPs by the cells had been investigated. In vitro toxicity studies in THP1 and H9c2 cell lines showed that CTNPs are safe even at a dose of 200 ng. The in vivo part of the study was carried out with different doses of Curcumin (1 mg-20 mg/kg body weight), Titaniumdioxide Nanoparticles (TNPs) (1 mg-5 mg/kg Body weight) and CTNPs (5 mg-10 mg/kg Body weight) in Sprague dawley rat models to determine the pharmacokinetics and genotoxicity of the nanoparticle. This was done by analysing the parameters like SGPT, SGOT, LDH, hematological parameters and biodistribution of the nanomaterial at different organ sites. Genotoxicity of samples were done by comet assay on blood cells. No significant toxicity was observed in the parameters in samples treated group compared to controls. The overall results indicated that the CTNPs are nontoxic and is highly stable with improved site specific application compared to native curcumin and are suitable for biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Carbonyl sulfide exchange in soils for better estimates of ecosystem carbon uptake

DOE PAGES

Whelan, Mary E.; Hilton, Timothy W.; Berry, Joseph A.; ...

2016-03-21

Carbonyl sulfide (COS) measurements are one of the emerging tools to better quantify gross primary production (GPP), the largest flux in the global carbon cycle. COS is a gas with a similar structure to CO 2; COS uptake is thought to be a proxy for GPP. However, soils are a potential source or sink of COS. This study presents a framework for understanding soil–COS interactions. Excluding wetlands, most of the few observations of isolated soils that have been made show small uptake of atmospheric COS. Recently, a series of studies at an agricultural site in the central United States foundmore » soil COS production under hot conditions an order of magnitude greater than fluxes at other sites. To investigate the extent of this phenomenon, soils were collected from five new sites and incubated in a variety of soil moisture and temperature states. We found that soils from a desert, an oak savannah, a deciduous forest, and a rainforest exhibited small COS fluxes, behavior resembling previous studies. However, soil from an agricultural site in Illinois, >800 km away from the initial central US study site, demonstrated comparably large soil fluxes under similar conditions. These new data suggest that, for the most part, soil COS interaction is negligible compared to plant uptake of COS. We present a model that anticipates the large agricultural soil fluxes so that they may be taken into account. Furthermore, while COS air-monitoring data are consistent with the dominance of plant uptake, improved interpretation of these data should incorporate the soil flux parameterizations suggested here.« less

3,4-Methylenedioxymethamphetamine and 3,4-methylenedioxyamphetamine destroy serotonin terminals in rat brain: quantification of neurodegeneration by measurement of (/sup 3/H)paroxetine-labeled serotonin uptake sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Battaglia, G.; Yeh, S.Y.; O'Hearn, E.

1987-09-01

This study examines the effects of repeated systemic administration (20 mg/kg s.c., twice daily for 4 days) of 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyamphetamine (MDA) on levels of brain monoamines, their metabolites and on the density of monoamine uptake sites in various regions of rat brain. Marked reductions (30-60%) in the concentration of 5-hydroxyindoleacetic acid were observed in cerebral cortex, hippocampus, striatum, hypothalamus and midbrain at 2 weeks after a 4-day treatment regimen of MDMA or MDA; less consistent reductions in serotonin (5-HT) content were observed in these brain regions. In addition, both MDMA and MDA caused comparable and substantial reductions (50-75%)more » in the density of (/sup 3/H)paroxetine-labeled 5-HT uptake sites in all brain regions examined. In contrast, neither MDMA nor MDA caused any widespread or long-term changes in the content of the catecholaminergic markers (i.e., norepinephrine, dopamine, 3,4 dihydroxyphenylacetic acid and homovanillic acid) or in the number of (/sup 3/H)mazindol-labeled norepinephrine or dopamine uptake sites in the brain regions examined. These data demonstrate that MDMA and MDA cause long-lasting neurotoxic effects with respect to both the functional and structural integrity of serotonergic neurons in brain. Furthermore, our measurement of reductions in the density of 5-HT uptake sites provides a means for quantification of the neurodegenerative effects of MDMA and MDA on presynaptic 5-HT terminals.« less

Characterization of nanoparticle uptake by endothelial cells.

PubMed

Davda, Jasmine; Labhasetwar, Vinod

2002-02-21

Endothelium is an important target for drug or gene therapy because of its important role in the biological system. In this paper, we have characterized nanoparticle uptake by endothelial cells in cell culture. Nanoparticles were formulated using poly DL-lactide-co-glycolide polymer containing bovine serum albumin as a model protein and 6-coumarin as a fluorescent marker. It was observed that the cellular uptake of nanoparticles depends on the time of incubation and the concentration of nanoparticles in the medium. The uptake of nanoparticles was rapid with confocal microscopy demonstrating their localization mostly in the cytoplasm. The mitogenic study demonstrated biocompatability of nanoparticles with the cells. The study thus demonstrates that nanoparticles could be used for localizing therapeutic agents or gene into endothelial cells. Nanoparticles localized in the endothelium could provide prolonged drug effects because of their sustained release characterics, and also could protect the encapsulated agent from enzymatic degradation.

Predicting pathologic tumor response to chemoradiotherapy with histogram distances characterizing longitudinal changes in 18F-FDG uptake patterns

PubMed Central

Tan, Shan; Zhang, Hao; Zhang, Yongxue; Chen, Wengen; D’Souza, Warren D.; Lu, Wei

2013-01-01

Purpose: A family of fluorine-18 (18F)-fluorodeoxyglucose (18F-FDG) positron-emission tomography (PET) features based on histogram distances is proposed for predicting pathologic tumor response to neoadjuvant chemoradiotherapy (CRT). These features describe the longitudinal change of FDG uptake distribution within a tumor. Methods: Twenty patients with esophageal cancer treated with CRT plus surgery were included in this study. All patients underwent PET/CT scans before (pre-) and after (post-) CRT. The two scans were first rigidly registered, and the original tumor sites were then manually delineated on the pre-PET/CT by an experienced nuclear medicine physician. Two histograms representing the FDG uptake distribution were extracted from the pre- and the registered post-PET images, respectively, both within the delineated tumor. Distances between the two histograms quantify longitudinal changes in FDG uptake distribution resulting from CRT, and thus are potential predictors of tumor response. A total of 19 histogram distances were examined and compared to both traditional PET response measures and Haralick texture features. Receiver operating characteristic analyses and Mann-Whitney U test were performed to assess their predictive ability. Results: Among all tested histogram distances, seven bin-to-bin and seven crossbin distances outperformed traditional PET response measures using maximum standardized uptake value (AUC = 0.70) or total lesion glycolysis (AUC = 0.80). The seven bin-to-bin distances were: L2 distance (AUC = 0.84), χ2 distance (AUC = 0.83), intersection distance (AUC = 0.82), cosine distance (AUC = 0.83), squared Euclidean distance (AUC = 0.83), L1 distance (AUC = 0.82), and Jeffrey distance (AUC = 0.82). The seven crossbin distances were: quadratic-chi distance (AUC = 0.89), earth mover distance (AUC = 0.86), fast earth mover distance (AUC = 0.86), diffusion distance (AUC = 0.88), Kolmogorov-Smirnov distance (AUC = 0.88), quadratic form distance (AUC = 0.87), and match distance (AUC = 0.84). These crossbin histogram distance features showed slightly higher prediction accuracy than texture features on post-PET images. Conclusions: The results suggest that longitudinal patterns in 18F-FDG uptake characterized using histogram distances provide useful information for predicting the pathologic response of esophageal cancer to CRT. PMID:24089897

Understanding the in vivo uptake kinetics of a phosphatidylethanolamine-binding agent (99m)Tc-Duramycin.

PubMed

Audi, Said; Li, Zhixin; Capacete, Joseph; Liu, Yu; Fang, Wei; Shu, Laura G; Zhao, Ming

2012-08-01

(99m)Tc-Duramycin is a peptide-based molecular probe that binds specifically to phosphatidylethanolamine (PE). The goal was to characterize the kinetics of molecular interactions between (99m)Tc-Duramycin and the target tissue. High level of accessible PE is induced in cardiac tissues by myocardial ischemia (30 min) and reperfusion (120 min) in Sprague-Dawley rats. Target binding and biodistribution of (99m)Tc-duramycin were captured using SPECT/CT. To quantify the binding kinetics, the presence of radioactivity in ischemic versus normal cardiac tissues was measured by gamma counting at 3, 10, 20, 60 and 180 min after injection. A partially inactivated form of (99m)Tc-Duramycin was analyzed in the same fashion. A compartment model was developed to quantify the uptake kinetics of (99m)Tc-Duramycin in normal and ischemic myocardial tissue. (99m)Tc-duramycin binds avidly to the damaged tissue with a high target-to-background radio. Compartment modeling shows that accessibility of binding sites in myocardial tissue to (99m)Tc-Duramycin is not a limiting factor and the rate constant of target binding in the target tissue is at 2.2 ml/nmol/min/g. The number of available binding sites for (99m)Tc-Duramycin in ischemic myocardium was estimated at 0.14 nmol/g. Covalent modification of D15 resulted in a 9-fold reduction in binding affinity. (99m)Tc-Duramycin accumulates avidly in target tissues in a PE-dependent fashion. Model results reflect an efficient uptake mechanism, consistent with the low molecular weight of the radiopharmaceutical and the relatively high density of available binding sites. These data help better define the imaging utilities of (99m)Tc-Duramycin as a novel PE-binding agent. Copyright © 2012 Elsevier Inc. All rights reserved.

Soil moisture and wild olive tree transpiration relationship in a water-limited Mediterranean ecosystem.

NASA Astrophysics Data System (ADS)

Curreli, M.; Montaldo, N.; Oren, R.

2016-12-01

Typically, during the dry summers, Mediterranean ecosystems are characterized by a simple dual PFTs system with strong-resistant woody vegetation and bare soil, since grass died. In these conditions the combined use of sap flow measurements, based on Granier's thermo-dissipative probes, eddy covariance technique and soil water content measurements provides a robust estimation of evapotranspiration (ET). An eddy covariance micrometeorological tower, thermo-dissipative probes based on the Granier technique and TDR sensors have been installed in the Orroli site in Sardinia (Italy). The site landscape is a mixture of Mediterranean patchy vegetation types: wild olives, different shrubs and herbaceous species, which died during the summer. 33 sap flow sensors have been installed at the Orroli site into 15 wild olives clumps with different characteristics (tree size, exposition to wind, solar radiation and soil depth). Sap flow measurements show the significantly impacts on transpiration of soil moisture, radiation and vapor pressure deficit (VPD). In addition ET is strongly influenced by the tree position into the clump. Results show a significant difference in sap flow rate for the south exposed trees compared to inside clump and north exposed trees. Using an innovative scaling procedure, the transpiration calculated from sap flow measurements have been compared to the eddy covariance ET. Sap flow measurements show night time uptake allows the recharge of the stem capacity, depleted during the day before due to transpiration. The night uptake increases with increasing VPD and transpiration but surprisingly it is independent to soil water content. Soil moisture probes allow monitoring spatial and temporal dynamics of water content at different soil depth and distance to the trees, and estimating its correlation with hydraulic lift. During the light hours soil moisture is depleted by roots to provide the water for transpiration and during night time the lateral roots transfer water from pasture in conjunction whit deep roots uptake to recharge water in the stem.

Differential Resistance Mechanisms to Glyphosate Result in Fitness Cost for Lolium perenne and L. multiflorum

PubMed Central

Fernández-Moreno, Pablo T.; Alcántara-de la Cruz, Ricardo; Smeda, Reid J.; De Prado, Rafael

2017-01-01

Multiple mechanisms of resistance to glyphosate are exhibited by populations of Lolium spp. worldwide. Association of resistance with growth and reproductive fitness is an important predictor for long-term success of glyphosate-resistant (R) versus glyphosate-susceptible (S) biotypes. Numerous studies were conducted on R- and S-biotypes of Italian ryegrass (Lolium multiflorum) and perennial ryegrass (L. perenne) to characterize the underlying mechanism(s) of glyphosate resistance and associate this with growth and reproductive fitness. L. perenne expressed both altered uptake and translocation as well as a genetic change at 106-Pro to –Ser, This pattern for two resistance mechanisms is unique. L. multiflorum also exhibited altered uptake and translocation as well as duplication of EPSPS gene copies. Reduced plant biomass and height for R-versus S-biotypes of both species was evident over two growing seasons. This resulted in S- versus R- L. multiflorum producing up to 47 and 38% more seeds in 2014 and 2015, respectively. S- L. perenne produced up to 20 and 30% more seeds in 2014 and 2015, respectively. Both non-target site and target-site mechanisms of glyphosate resistance can render Lolium spp. at a competitive disadvantage. This has long-term implications for the success of glyphosate-resistant plants in the absence of selection pressure. PMID:29089958

Sources and sinks of selected trace gases in the tropospheric boundary layer of the eastern United States

NASA Astrophysics Data System (ADS)

White, Marguerite L.

This dissertation describes three major research projects with the common goal of characterizing sources and sinks of trace gases of strong relevance to regional air quality and global climate issues. In the first study, volatile organic compound (VOC) measurements collected at a marine and continental site in northern New England were compared and examined for evidence of regional VOC sources. Biogenic VOCs, including isoprene, monoterpenes, and oxygenated VOCs, were significant components of the total reactivity at both locations. However, very different VOC distributions were observed for each site. The impact of local anthropogenic hydrocarbon sources such as liquefied petroleum gas (LPG) leakage was also evident at both sites. During the campaign, a propane flux of 9 (+/-2) x 109 molecules cm-2 s-1 was calculated for the continental site. In the second study, three hydrocarbon sources were investigated for their potential contributions to the summertime atmospheric toluene enhancements observed at a rural location in southern New Hampshire. These sources included: (1) warm season fuel evaporation emissions, (2) local industrial emissions, and (3) local vegetative emissions. The estimated contribution of fuel evaporation emissions (16-30 pptv d-1) could not fully account for observed summertime toluene enhancements (20-50 pptv d-1). Vegetation enclosure measurements suggested biogenic toluene emissions (5 and 12 pptv d-1 for alfalfa and pine trees) made significant contributions to summertime enhancements. Industrial toluene emissions, estimated at 7 pptv d-1, most likely occurred year round rather than seasonally. Finally, controls over carbonyl sulfide (COS) uptake in a temperate loblolly pine forest grown under ambient and elevated CO2 were examined in the third study. Vegetative consumption dominated net ecosystem COS uptake (10 to 40 pmol m-2 s-1) under both CO2 regimes. Environmental controls over vegetation stomatal conductance and photosynthetic capacity were the major factors influencing COS uptake rates. The loblolly pines exhibited substantial COS consumption overnight (50% of daytime rates) that was independent of CO2 assimilation. This suggests current estimates of the global vegetative COS sink, which assume that COS and CO2 are consumed simultaneously, may need to be reevaluated.

Use of a chemical equilibrium model to describe surface properties and uptake of cadmium, strontium, and lead by Chlorella (UTEX 252)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hassett, J.M.

1988-01-01

Metal-aquatic biota interactions are important in both natural and engineered systems. In this study, the uptake of cadmium, strontium and lead by the unicellular green alga Chlorella (UTEX 252) was investigated. Variables included metal concentration, pH, and ionic strength. Data gathered included dry weights (mg/l), cell counts (cells/ml), electrophoretic mobilities (EPMs, {mu}m/sec/V/cm) of metal-free and metal-exposed cells, and metal uptake - difference in concentration in filtrate of cell-metal and cell-free metal solutions. Derived data included cell volumes and surface area, uptake on a {mu}M/m{sup 2} basis, {zeta}-potentials, diffuse layer potentials and charge densities. Typical uptake values were 1.1, 5.2, andmore » 6 {mu}M/m{sup 2} for Cd, Pb, and Sr, respectively, from solutions of pH 6, ionic strength 0.02M, and metal concentration 10{sup {minus}4} M. Cell EPMs were insensitive to metal; under certain conditions, however, (pM > 4, pH > 8), cadmium exposed cells exhibited a reversal in surface charge from negative to positive. The chemical equilibrium model MINEQL1 + STANFORD was used to model algal surface properties and metal uptake. Input data included site pK, density, and {Delta}pK, estimated from EPM-pH data. The model described surface properties of Chlorella (UTEX 252) as judged by a close fit of {zeta}-potentials and model-derived diffuse layer potentials. Metal uptake was modelled by adjusting site density and/or metal-surface site equilibrium constants. Attempts to model surface properties and metal uptake simultaneously were not successful.« less

BOREAS TE-1 CO2 and CH4 Flux Data Over the SSA-OBS Site

NASA Technical Reports Server (NTRS)

Anderson, Darwin; Papagno, Andrea; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor)

2000-01-01

The BOREAS TE-1 team collected various data to characterize the soil-plant systems in the BOREAS SSA. Particular emphasis was placed on nutrient biochemistry, the stores and transfers of organic carbon, and how the characteristics were related to measured methane fluxes. The overall transect in the Prince Albert National Park (Saskatchewan, Canada) included the major plant communities and related soils that occurred in that section of the boreal forest. Soil physical, chemical, and biological measurements along the transect were used to characterize the static environment, which allowed them to be related to methane fluxes. Chamber techniques were used to provide a measure of methane production/uptake. Chamber measurements coupled with flask sampling were used to determine the seasonality of methane fluxes. This particular data set contains carbon dioxide and methane flux values from the SSA-OBS site. The data were collected from 09-Jun to 04-Sep-1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Characterization of the growth and auxin physiology of roots of the tomato mutant, diageotropica

NASA Technical Reports Server (NTRS)

Muday, G. K.; Lomax, T. L.; Rayle, D. L.

1995-01-01

Roots of the tomato (Lycopersicon esculentum, Mill.) mutant (diageotropica (dgt) exhibit an altered phenotype. These roots are agravitropic and lack lateral roots. Relative to wild-type (VFN8) roots, dgt roots are less sensitive to growth inhibition by exogenously applied IAA and auxin transport inhibitors (phytotropins), and the roots exhibit a reduction in maximal growth inhibition in response to ethylene. However, IAA transport through roots, binding of the phytotropin, tritiated naphthylphthalamic acid ([3H]NPA), to root microsomal membranes, NPA-sensitive IAA uptake by root segments, and uptake of [3H]NPA into root segments are all similar in mutant and wild-type roots. We speculate that the reduced sensitivity of dgt root growth to auxin-transport inhibitors and ethylene is an indirect result of the reduction in sensitivity to auxin in this single gene, recessive mutant. We conclude that dgt roots, like dgt shoots, exhibit abnormalities indicating they have a defect associated with or affecting a primary site of auxin perception or action.

Charge-conversional poly(amino acid)s derivatives as a drug delivery carrier in response to the tumor environment.

PubMed

Yoon, Se Rim; Yang, Hee-Man; Park, Chan Woo; Lim, Sujin; Chung, Bong Hyun; Kim, Jong-Duk

2012-08-01

A charge-converting and pH-dependent nanocarrier was achieved by conjugating 2,3-dimethylmaleic anhydride (DMMA) to the amino group of an octadecyl grafted poly (2-hydroxyethyl aspartamide) (PHEA-g-C(18)-NH(2)) backbone, thereby forming a spherical micelle. PHEA, a poly(amino acid)s derivative, was derived from poly(succinimide), which is biocompatible and biodegradable. DMMA, a detachable component at the tumor site, was added, preventing aggregation with negative blood serum and enhancing the nanocarrier's cellular uptake. The polymeric micelle was comprehensively characterized and doxorubicin was encapsulated successively. The cellular uptake and anticancer therapeutic effect were evaluated by flow cytometry, confocal laser scanning microscopy, and a MTT assay. The properties of the nanocarrier can further be exploited to develop an early detection module for cancer. The present work is also expected to advance the study of designing smart carriers for drug and gene delivery. Copyright © 2012 Wiley Periodicals, Inc.

Groundwater discharge by evapotranspiration, flow of water in unsaturated soil, and stable isotope water sourcing in areas of sparse vegetation, Amargosa Desert, Nye County, Nevada

USGS Publications Warehouse

Moreo, Michael T.; Andraski, Brian J.; Garcia, C. Amanda

2017-08-29

This report documents methodology and results of a study to evaluate groundwater discharge by evapotranspiration (GWET) in sparsely vegetated areas of Amargosa Desert and improve understanding of hydrologic-continuum processes controlling groundwater discharge. Evapotranspiration and GWET rates were computed and characterized at three sites over 2 years using a combination of micrometeorological, unsaturated zone, and stable-isotope measurements. One site (Amargosa Flat Shallow [AFS]) was in a sparse and isolated area of saltgrass (Distichlis spicata) where the depth to groundwater was 3.8 meters (m). The second site (Amargosa Flat Deep [AFD]) was in a sparse cover of predominantly shadscale (Atriplex confertifolia) where the depth to groundwater was 5.3 m. The third site (Amargosa Desert Research Site [ADRS]), selected as a control site where GWET is assumed to be zero, was located in sparse vegetation dominated by creosote bush (Larrea tridentata) where the depth to groundwater was 110 m.Results indicated that capillary rise brought groundwater to within 0.9 m (at AFS) and 3 m (at AFD) of land surface, and that GWET rates were largely controlled by the slow but relatively persistent upward flow of water through the unsaturated zone in response to atmospheric-evaporative demands. Greater GWET at AFS (50 ± 20 millimeters per year [mm/yr]) than at AFD (16 ± 15 mm/yr) corresponded with its shallower depth to the capillary fringe and constantly higher soil-water content. The stable-isotope dataset for hydrogen (δ2H) and oxygen (δ18O) illustrated a broad range of plant-water-uptake scenarios. The AFS saltgrass and AFD shadscale responded to changing environmental conditions and their opportunistic water use included the time- and depth-variable uptake of unsaturated-zone water derived from a combination of groundwater and precipitation. These results can be used to estimate GWET in other areas of Amargosa Desert where hydrologic conditions are similar.

Sorption of Metal Ions on Clay Minerals.

PubMed

Schlegel; Charlet; Manceau

1999-12-15

The mechanism of Co uptake from aqueous solution onto hectorite (a magnesian smectite) and its impact on the stability of this clay mineral were investigated as a function of Co concentration (TotCo = 20 to 200 µM, 0.3 M NaNO(3)) and ionic strength (0.3 and 0.01 M NaNO(3), TotCo = 100 µM) by combining kinetics measurements and Co K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The morphology of the sorbent phase was characterized by atomic force microscopy (AFM) and consists of lath-type particles bounded by large basal planes and layer edges. At low ionic strength (0.01 M NaNO(3)), important Co uptake occurred within the first 5 min of reaction, consistent with Co adsorption on exchange sites of hectorite basal planes. Thereafter, the sorption rate dramatically decreased. In contrast, at high ionic strength (0.3 M NaNO(3)), Co uptake rate was much slower within the first 5 min and afterward higher than at 0.01 M NaNO(3), consistent with Co adsorption on specific surface sites located on the edges of hectorite. Time-dependent isotherms for Co uptake at high ionic strength indicated the existence of several sorption mechanisms having distinct equilibration times. The dissolution of hectorite was monitored before and after Co addition. A congruent dissolution regime was observed prior to Co addition. Just after Co addition, an excess release of Mg relatively to congruent dissolution rates occurred at both high and low ionic strengths. At high ionic strength, this excess release nearly equaled the amount of sorbed Co. The dissolution rate of hectorite then decreased at longer Co sorption times. EXAFS spectra of hectorite reacted with Co at high and low ionic strengths and for reaction times longer than 6 h, exhibited similar features, suggesting that the local structural environments of Co atoms are similar. Spectral simulations revealed the occurrence of approximately 2 Mg and approximately 2 Si neighboring cations at interatomic distances characteristic of edge-sharing linkages between Co and Mg octahedra and corner-sharing linkages between Co octahedra and Si tetrahedra, respectively. This local structure is characteristic of inner sphere mononuclear surface complexes at layer edges of hectorite platelets. The occurrence of these complexes even at low ionic strength apparently conflicts with kinetics results, as exchangeable divalent cations are known to form outer sphere surface complexes. To clarify this issue, the amount of Co adsorbed on exchange sites was calculated from the solute Co concentration, assuming that cation exchange was always at equilibrium. These calculations showed that sorbed Co was transferred within 48 h from exchange sites to edge sorption sites. Copyright 1999 Academic Press.

A novel metal-organic framework for high storage and separation of acetylene at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, Xing, E-mail: star1987@hdu.edu.cn; Wang, Huizhen; Ji, Zhenguo

2016-09-15

A novel 3D microporous metal-organic framework with NbO topology, [Cu{sub 2}(L)(H{sub 2}O){sub 2}]∙(DMF){sub 6}·(H{sub 2}O){sub 2} (ZJU-10, ZJU = Zhejiang University; H{sub 4}L =2′-hydroxy-[1,1′:4′,1″-terphenyl]-3,3″,5,5″-tetracarboxylic acid; DMF =N,N-dimethylformamide), has been synthesized and structurally characterized. With suitable pore sizes and open Cu{sup 2+} sites, ZJU-10a exhibits high BET surface area of 2392 m{sup 2}/g, as well as moderately high C{sub 2}H{sub 2} volumetric uptake capacity of 132 cm{sup 3}/cm{sup 3}. Meanwhile, ZJU-10a is a promising porous material for separation of acetylene from methane and carbon dioxide gas mixtures at room temperature. - Graphical abstract: A new NbO-type microporous metal-organic framework ZJU-10 withmore » suitable pore size and open Cu{sup 2+} sites was synthesized to realize the strong interaction with acetylene molecules, which can separate the acetylene from methane and carbon dioxane gas mixtures at room temperature. Display Omitted - Highlights: • A novel 3D NbO-type microporous metal-organic framework ZJU-10 was solvothermally synthesized and structurally characterized. • ZJU-10a exhibits high BET surface area of 2392 m{sup 2}/g. • ZJU-10a shows a moderately high C{sub 2}H{sub 2} gravimetric (volumetric) uptake capacity of 174 (132) cm{sup 3}/g at 298 K and 1 bar. • ZJU-10a can separate acetylene from methane and carbon dioxide gas mixtures at room temperature.« less

Species turnover (β-diversity) in ectomycorrhizal fungi linked to NH4+ uptake capacity.

PubMed

Kranabetter, J M; Hawkins, B J; Jones, M D; Robbins, S; Dyer, T; Li, T

2015-12-01

Ectomycorrhizal (EcM) fungal communities may be shaped by both deterministic and stochastic processes, potentially influencing ecosystem development and function. We evaluated community assembly processes for EcM fungi of Pseudotsuga menziesii among 12 sites up to 400 km apart in southwest British Columbia (Canada) by investigating species turnover (β-diversity) in relation to soil nitrogen (N) availability and physical distance. We then examined functional traits for an N-related niche by quantifying net fluxes of NH4+, NO3- and protons on excised root tips from three contrasting sites using a microelectrode ion flux measurement system. EcM fungal communities were well aligned with soil N availability and pH, with no effect of site proximity (distance-decay curve) on species assemblages. Species turnover was significant (β(1/2) = 1.48) along soil N gradients, with many more Tomentella species on high N than low N soils, in contrast to Cortinarius species. Ammonium uptake was greatest in the spring on the medium and rich sites and averaged over 190 nmol/m(2)/s for Tomentella species. The lowest uptake rates of NH4+ were by nonmycorrhizal roots of axenically grown seedlings (10 nmol/m(2)/s), followed by Cortinarius species (60 nmol/m(2)/s). EcM roots from all sites displayed only marginal uptake of nitrate (8.3 nmol/m(2)/s). These results suggest NH4+ uptake capacity is an important functional trait influencing the assembly of EcM fungal communities. The diversity of EcM fungal species across the region arguably provides critical belowground adaptations to organic and inorganic N supply that are integral to temperate rainforest ecology. © 2015 John Wiley & Sons Ltd.

CO2 exchange in the Hudson Bay lowlands: Community characteristics and multispectral reflectance properties

NASA Technical Reports Server (NTRS)

Whiting, Gary J.

1994-01-01

Net ecosystem CO2 exchange was measured during the 1990 growing season (June to August) along a transect starting 10 km inland from James Bay and extending 100 km interior to Kinosheo Lake, Ontario. Sites were chosen in three distinct areas: a coastal fen, an interior fen, and a bog. For the most productive sites in the bog, net daily uptake rates reached a maximum of 2.5 g C-CO2 m(exp -2)/d with an area-weighted exchange of 0.3 g C-CO2 m(exp -2)/d near midsummer. This site was estimated to be a net carbon source of 9 g C-CO2 m(exp -2) to the atmosphere over a 153-day growing season. The interior fen was less productive on a daily basis with a net maximum uptake of 0.5 g C-CO2 m(exp -2)/d and with corresponding area-weighted uptake of 0.1 g C-CO2 m(exp -2)/d during midsummer. Early and late season release of carbon to the atmosphere resulted in a net loss of 21 g C-CO2 m(exp -2) over the growing season from this site. The coastal fen was the most productive site with uptake rates peaking near 1.7 g C-CO2 m(exp -2)/d which corresponded to an area-weighted uptake of 0.8 g C-CO2 m(exp -2)/d during midsummer and an estimated net uptake of 6 g C-CO2 m(exp -2) for the growing season. Associated with net CO2 exchange measurements, multispectral reflectance properties of the sites were measured over the growing season using portable radiometers. These properties were related to exchange rates with the goal of examining the potential for satellite remote sensing to monitor biosphere/atmosphere CO2 exchange in this biome. The normalized difference vegetation index (NDVI) computed from surface reflectance was correlated with net CO2 exchange for all sites with the exception of areas with large proportions of Sphagnum moss cover. These mosses have greater near-infrared reflectance than typical surrounding vegetation and may require special adjustment for regional exchange/remote sensing applications.

Safety and biodistribution of 111In-amatuximab in patients with mesothelin expressing cancers using Single Photon Emission Computed Tomography-Computed Tomography (SPECT-CT) imaging

PubMed Central

Adler, Stephen; Mena, Esther; Kurdziel, Karen; Maltzman, Julia; Wallin, Bruce; Hoffman, Kimberly; Pastan, Ira; Paik, Chang Hum; Choyke, Peter; Hassan, Raffit

2015-01-01

Amatuximab is a chimeric high-affinity monoclonal IgG1/k antibody targeting mesothelin that is being developed for treatment of mesothelin-expressing cancers. Considering the ongoing clinical development of amatuximab in these cancers, our objective was to characterize the biodistribution, and dosimetry of 111Indium (111In) radiolabelled amatuximab in mesothelin-expressing cancers. Between October 2011 and February 2013, six patients including four with malignant mesothelioma and two with pancreatic adenocarcinoma underwent Single Photon Emission Computed Tomography-Computed Tomography (SPECT/CT) imaging following administration of 111In amatuximab. SPECT/CT images were obtained at 2–4 hours, 24–48 hours and 96–168 hours after radiotracer injection. In all patients, tumor to background ratios (TBR) consistently met or exceeded an uptake of 1.2 (range 1.2–62.0) which is considered the minimum TBR that can be visualized. TBRs were higher in tumors of patients with mesothelioma than pancreatic adenocarcinoma. 111In-amatuximab uptake was noted in both primary tumors and metastatic sites. The radiotracer dose was generally well-tolerated and demonstrated physiologic uptake in the heart, liver, kidneys and spleen. This is the first study to show tumor localization of an anti-mesothelin antibody in humans. Our results show that 111In-amatuximab was well tolerated with a favorable dosimetry profile. It localizes to mesothelin expressing cancers with a higher uptake in mesothelioma than pancreatic cancer. PMID:25756664

Copper uptake by the water hyacinth. [Eichornia crassipes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, T.A.; Hardy, J.K.

1987-01-01

Factors affecting Cu/sup +2/ uptake by the water hyacinth (Eichornia crassipes) were examined. Two phases of copper uptake were observed throughout the uptake range (1-1000 mg/1). An initial rapid uptake phase of 4 hours followed by a slower, near linear uptake phase extending past 48 hours was observed. Stirring the solution enhanced uptake, suggesting copper removal is partially diffusion limited. Variations in pH over the range of 3 to 10 did not significantly affect uptake. Increasing the root mass of the plant increased the amount of copper taken up. As solution volume was increased more copper was removed. The presencemore » of complexing agents during the uptake phase reduced copper uptake. The inability of complexing agents to recover all copper initially removed by a plant suggests a migration to sites within the plant.« less

Different components of /sup 3/H-imipramine binding in rat brain membranes: relation to serotonin uptake sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gobbi, M.; Taddei, C.; Mennini, T.

1988-01-01

In the present paper, the authors confirm and extend previous studies showing heterogeneous /sup 3/H-imipramine (/sup 3/H-IMI) binding sites. Inhibition curves of various drugs (serotonin, imipramine, desmethyl-imipramine, d-fenfluramine, d-norfenfluramine and indalpine, a potent serotonin uptake inhibitor) obtained using 2 nM /sup 3/H-IMI and in presence of 120 mM NaCl, confirmed the presence of at least three /sup 3/H-IMI binding sites: two of these were serotonin-insensitive while the third one was selectively inhibited by serotonin and indalpine with nanomolar affinities. Moreover this last component was found to be selectively modulated by chronic imipramine treatment thus suggesting a close relation to serontoninmore » uptake mechanism. These data indicate that the use of a more selective inhibitors of the serotonin-sensitive component (like indalpine or serotonin itself) to define non specific /sup 3/H-IMI, may be of help in understanding its relation with serotonin uptake system. 22 references, 2 figures, 2 tables.« less

Widespread Distribution and Functional Specificity of the Copper Importer CcoA: Distinct Cu Uptake Routes for Bacterial Cytochrome c Oxidases

DOE PAGES

Khalfaoui-Hassani, Bahia; Wu, Hongjiang; Blaby-Haas, Crysten E.; ...

2018-02-27

ABSTRACT Cytochromecoxidases are members of the heme-copper oxidase superfamily. These enzymes have different subunits, cofactors, and primary electron acceptors, yet they all contain identical heme-copper (Cu B) binuclear centers within their catalytic subunits. The uptake and delivery pathways of the Cu Batom incorporated into this active site, where oxygen is reduced to water, are not well understood. Our previous work with the facultative phototrophic bacteriumRhodobacter capsulatusindicated that the copper atom needed for the Cu Bsite ofcbb 3-type cytochromecoxidase (cbb 3-Cox) is imported to the cytoplasm by a major facilitator superfamily-type transporter, CcoA. In this study, a comparative genomic analysis ofmore » CcoA orthologs in alphaproteobacterial genomes showed that CcoA is widespread among organisms and frequently co-occurs with cytochromecoxidases. To define the specificity of CcoA activity, we investigated its function inRhodobacter sphaeroides, a close relative ofR. capsulatusthat contains bothcbb 3- andaa 3-Cox. Phenotypic, genetic, and biochemical characterization of mutants lacking CcoA showed that in its absence, or even in the presence of its bypass suppressors, only the production ofcbb 3-Cox and not that ofaa 3-Cox was affected. We therefore concluded that CcoA is dedicated solely tocbb 3-Cox biogenesis, establishing that distinct copper uptake systems provide the Cu Batoms to the catalytic sites of these two similar cytochromecoxidases. These findings illustrate the large variety of strategies that organisms employ to ensure homeostasis and fine control of copper trafficking and delivery to the target cuproproteins under different physiological conditions. IMPORTANCEThecbb 3- andaa 3-type cytochromecoxidases belong to the widespread heme-copper oxidase superfamily. They are membrane-integral cuproproteins that catalyze oxygen reduction to water under hypoxic and normoxic growth conditions. These enzymes diverge in terms of subunit and cofactor composition, yet they all share a conserved heme-copper binuclear site within their catalytic subunit. In this study, we show that the copper atoms of the catalytic center of two similar cytochromecoxidases from this superfamily are provided by different copper uptake systems during their biogenesis. This finding illustrates different strategies by which organisms fine-tune the trafficking of copper, which is an essential but toxic micronutrient.« less

Widespread Distribution and Functional Specificity of the Copper Importer CcoA: Distinct Cu Uptake Routes for Bacterial Cytochrome c Oxidases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khalfaoui-Hassani, Bahia; Wu, Hongjiang; Blaby-Haas, Crysten E.

ABSTRACT Cytochromecoxidases are members of the heme-copper oxidase superfamily. These enzymes have different subunits, cofactors, and primary electron acceptors, yet they all contain identical heme-copper (Cu B) binuclear centers within their catalytic subunits. The uptake and delivery pathways of the Cu Batom incorporated into this active site, where oxygen is reduced to water, are not well understood. Our previous work with the facultative phototrophic bacteriumRhodobacter capsulatusindicated that the copper atom needed for the Cu Bsite ofcbb 3-type cytochromecoxidase (cbb 3-Cox) is imported to the cytoplasm by a major facilitator superfamily-type transporter, CcoA. In this study, a comparative genomic analysis ofmore » CcoA orthologs in alphaproteobacterial genomes showed that CcoA is widespread among organisms and frequently co-occurs with cytochromecoxidases. To define the specificity of CcoA activity, we investigated its function inRhodobacter sphaeroides, a close relative ofR. capsulatusthat contains bothcbb 3- andaa 3-Cox. Phenotypic, genetic, and biochemical characterization of mutants lacking CcoA showed that in its absence, or even in the presence of its bypass suppressors, only the production ofcbb 3-Cox and not that ofaa 3-Cox was affected. We therefore concluded that CcoA is dedicated solely tocbb 3-Cox biogenesis, establishing that distinct copper uptake systems provide the Cu Batoms to the catalytic sites of these two similar cytochromecoxidases. These findings illustrate the large variety of strategies that organisms employ to ensure homeostasis and fine control of copper trafficking and delivery to the target cuproproteins under different physiological conditions. IMPORTANCEThecbb 3- andaa 3-type cytochromecoxidases belong to the widespread heme-copper oxidase superfamily. They are membrane-integral cuproproteins that catalyze oxygen reduction to water under hypoxic and normoxic growth conditions. These enzymes diverge in terms of subunit and cofactor composition, yet they all share a conserved heme-copper binuclear site within their catalytic subunit. In this study, we show that the copper atoms of the catalytic center of two similar cytochromecoxidases from this superfamily are provided by different copper uptake systems during their biogenesis. This finding illustrates different strategies by which organisms fine-tune the trafficking of copper, which is an essential but toxic micronutrient.« less

Comparison of Carbon Sequestration Rates and Energy Balance of Turf in the Denver Urban Ecosystem and an Adjacent Native Grassland

NASA Astrophysics Data System (ADS)

Thienelt, T. S.; Anderson, D. E.; Powell, K. M.

2011-12-01

Urban ecosystems are currently characterized by rapid growth, are expected to continually expand and, thus, represent an important driver of land use change. A significant component of urban ecosystems is lawns, potentially the single largest irrigated "crop" in the U.S. Beginning in March of 2011 (ahead of the growing season), eddy covariance measurements of net carbon exchange and evapotranspiration along with energy balance fluxes were conducted for a well-watered, fertilized lawn (rye-bluegrass-mix) in metropolitan Denver and for a nearby tallgrass prairie (big bluestem, switchgrass, cheatgrass, blue grama). Due to the semi-arid climate conditions of the Denver region, differences in management (i.e., irrigation and fertilization) are expected to have a discernible impact on ecosystem productivity and thus on carbon sequestration rates, evapotranspiration, and the sensible and latent heat partitioning of the energy balance. By mid-July, preliminary data indicated that cumulative evapotranspiration was approximately 270 mm and 170 mm for urban and native grasslands, respectively, although cumulative carbon sequestration at that time was similar for both (approximately 40 mg/m2). However, the pattern of carbon exchange differed between the grasslands. Both sites showed daily net uptake of carbon starting in late May, but the urban lawn displayed greater diurnal variability as well as greater uptake rates in general, especially following fertilization in mid-June. In contrast, the trend of carbon uptake at the prairie site was occasionally reversed following strong convective precipitation events, resulting in a temporary net release of carbon. The continuing acquisition of data and investigation of these relations will help us assess the potential impact of urban growth on regional carbon sequestration.

A Numerical Study of the Effect of Periodic Nutrient Supply on Pathways of Carbon in a Coastal Upwelling Regime

NASA Technical Reports Server (NTRS)

Carr, Mary-Elena

1998-01-01

A size-based ecosystem model was modified to include periodic upwelling events and used to evaluate the effect of episodic nutrient supply on the standing stock, carbon uptake, and carbon flow into mesozooplankton grazing and sinking flux in a coastal upwelling regime. Two ecosystem configurations were compared: a single food chain made up of net phytoplankton and mesozooplankton (one autotroph and one heterotroph, A1H1), and three interconnected food chains plus bacteria (three autotrophs and four heterotrophs, A3H4). The carbon pathways in the A1H1 simulations were under stronger physical control than those of the A3H4 runs, where the small size classes are not affected by frequent upwelling events. In the more complex food web simulations, the microbial pathway determines the total carbon uptake and grazing rates, and regenerated nitrogen accounts for more than half of the total primary production for periods of 20 days or longer between events. By contrast, new production, export of carbon through sinking and mesozooplankton grazing are more important in the A1H1 simulations. In the A3H4 simulations, the turnover time scale of the autotroph biomass increases as the period between upwelling events increases, because of the larger contribution of slow-growing net phytoplankton. The upwelling period was characterized for three upwelling sites from the alongshore wind speed measured by the NASA Scatterometer (NSCAT) and the corresponding model output compared with literature data. This validation exercise for three upwelling sites and a downstream embayment suggests that standing stock, carbon uptake and size fractionation were best supported by the A3H4 simulations, while the simulated sinking fluxes are not distinguishable in the two configurations.

A novel insulin receptor-binding protein from Momordica charantia enhances glucose uptake and glucose clearance in vitro and in vivo through triggering insulin receptor signaling pathway.

PubMed

Lo, Hsin-Yi; Ho, Tin-Yun; Li, Chia-Cheng; Chen, Jaw-Chyun; Liu, Jau-Jin; Hsiang, Chien-Yun

2014-09-10

Diabetes, a common metabolic disorder, is characterized by hyperglycemia. Insulin is the principal mediator of glucose homeostasis. In a previous study, we identified a trypsin inhibitor, named Momordica charantia insulin receptor (IR)-binding protein (mcIRBP) in this study, that might interact with IR. The physical and functional interactions between mcIRBP and IR were clearly analyzed in the present study. Photo-cross-linking coupled with mass spectrometry showed that three regions (17-21, 34-40, and 59-66 residues) located on mcIRBP physically interacted with leucine-rich repeat domain and cysteine-rich region of IR. IR-binding assay showed that the binding behavior of mcIRBP and insulin displayed a cooperative manner. After binding to IR, mcIRBP activated the kinase activity of IR by (5.87 ± 0.45)-fold, increased the amount of phospho-IR protein by (1.31 ± 0.03)-fold, affected phosphoinositide-3-kinase/Akt pathways, and consequently stimulated the uptake of glucose in 3T3-L1 cells by (1.36 ± 0.12)-fold. Intraperitoneal injection of 2.5 nmol/kg mcIRBP significantly decreased the blood glucose levels by 20.9 ± 3.2% and 10.8 ± 3.6% in normal and diabetic mice, respectively. Microarray analysis showed that mcIRBP affected genes involved in insulin signaling transduction pathway in mice. In conclusion, our findings suggest that mcIRBP is a novel IRBP that binds to sites different from the insulin-binding sites on IR and stimulates both the glucose uptake in cells and the glucose clearance in mice.

A greenhouse and field-based study to determine the accumulation of arsenic in common homegrown vegetables grown in mining-affected soils

PubMed Central

Ramirez-Andreotta, Monica D.; Brusseau, Mark L.; Artiola, Janick F.; Maier, Raina M.

2012-01-01

The uptake of arsenic by plants from contaminated soils presents a health hazard that may affect home gardeners neighboring contaminated environments. A controlled greenhouse study was conducted in parallel with a co-created citizen science program (home garden experiment) to characterize the uptake of arsenic by common homegrown vegetables near the Iron King Mine and Humboldt Smelter Superfund site in southern Arizona. The greenhouse and home garden arsenic soil concentrations varied considerably, ranging from 2.35 to 533 mg kg−1. In the greenhouse experiment four vegetables were grown in three different soil treatments and in the home garden experiment a total of 63 home garden produce samples were obtained from 19 properties neighboring the site. All vegetables accumulated arsenic in both the greenhouse and home garden experiments, ranging from 0.01 to 23.0 mg kg−1 dry weight. Bioconcentration factors were determined and show that arsenic uptake decreased in the order: Asteraceae > Brassicaceae > Amaranthaceae > Cucurbitaceae > Liliaceae > Solanaceae > Fabaceae. Certain members of the Asteraceae and Brassicaceae plant families have been previously identified as hyperaccumulator plants, and it can be inferred that members of these families have genetic and physiological capacity to accumulate, translocate, and resist high amounts of metals. Additionally, a significant linear correlation was observed between the amount of arsenic that accumulated in the edible portion of the plant and the arsenic soil concentration for the Asteraceae, Brassicaceae, Amaranthaceae, and Fabaceae families. The results suggest that home gardeners neighboring mining operations or mine tailings with elevated arsenic levels should be made aware that arsenic can accumulate considerably in certain vegetables, and in particular, it is recommended that gardeners limit consumption of vegetables from the Asteraceae and Brassicaceae plant families. PMID:23201696

Functional intercalated nanocomposites with chitosan-glutathione-glycylsarcosine and layered double hydroxides for topical ocular drug delivery.

PubMed

Xu, Tingting; Xu, Xiaoyue; Gu, Yan; Fang, Lei; Cao, Feng

2018-01-01

To enhance ocular bioavailability, the traditional strategies have focused on prolonging precorneal retention and improving corneal permeability by nano-carriers with positive charge, thiolated polymer, absorption enhancer and so on. Glycylsarcosine (GS) as an active target ligand of the peptide tranpsporter-1 (PepT-1), could specific interact with the PepT-1 on the cornea and guide the nanoparticles to the treating site. The objective of the study was to explore the active targeting intercalated nanocomposites based on chitosan-glutathione-glycylsarcosine (CG-GS) and layered double hydroxides (LDH) as novel carriers for the treatment of mid-posterior diseases. CG-GS-LDH intercalated nanocomposites were prepared by the coprecipitation hydrothermal method. In vivo precorneal retention study, ex vivo fluorescence images, in vivo experiment for distribution and irritation were studied in rabbits. The cytotoxicity and cellular uptake were studied in human corneal epithelial primary cells (HCEpiC). CG-GS-LDH nanocomposites were prepared successfully and characterized by FTIR and XRD. Experiments with rabbits showed longer precorneal retention and higher distribution of fluorescence probe/model drug. In vitro cytological study, CG-GS-LDH nanocomposites exhibited enhanced cellular uptake compared to pure drug solution. Furthermore, the investigation of cellular uptake mechanisms demonstrated that both the active transport by PepT-1 and clathrin-mediated endocytosis were involved in the internalization of CG-GS-LDH intercalated nanocomposites. An ocular irritation study and a cytotoxicity test indicated that these nanocomposites produced no significant irritant effects. The active targeting intercalated nanocomposites could have great potential for topical ocular drug delivery due to the capacity for prolonging the retention on the ocular surface, enhancing the drug permeability through the cornea, and efficiently delivering the drug to the targeted site.

Functional intercalated nanocomposites with chitosan-glutathione-glycylsarcosine and layered double hydroxides for topical ocular drug delivery

PubMed Central

Gu, Yan

2018-01-01

Background To enhance ocular bioavailability, the traditional strategies have focused on prolonging precorneal retention and improving corneal permeability by nano-carriers with positive charge, thiolated polymer, absorption enhancer and so on. Glycylsarcosine (GS) as an active target ligand of the peptide tranpsporter-1 (PepT-1), could specific interact with the PepT-1 on the cornea and guide the nanoparticles to the treating site. Purpose The objective of the study was to explore the active targeting intercalated nanocomposites based on chitosan-glutathione-glycylsarcosine (CG-GS) and layered double hydroxides (LDH) as novel carriers for the treatment of mid-posterior diseases. Materials and methods CG-GS-LDH intercalated nanocomposites were prepared by the coprecipitation hydrothermal method. In vivo precorneal retention study, ex vivo fluorescence images, in vivo experiment for distribution and irritation were studied in rabbits. The cytotoxicity and cellular uptake were studied in human corneal epithelial primary cells (HCEpiC). Results CG-GS-LDH nanocomposites were prepared successfully and characterized by FTIR and XRD. Experiments with rabbits showed longer precorneal retention and higher distribution of fluorescence probe/model drug. In vitro cytological study, CG-GS-LDH nanocomposites exhibited enhanced cellular uptake compared to pure drug solution. Furthermore, the investigation of cellular uptake mechanisms demonstrated that both the active transport by PepT-1 and clathrin-mediated endocytosis were involved in the internalization of CG-GS-LDH intercalated nanocomposites. An ocular irritation study and a cytotoxicity test indicated that these nanocomposites produced no significant irritant effects. Conclusions The active targeting intercalated nanocomposites could have great potential for topical ocular drug delivery due to the capacity for prolonging the retention on the ocular surface, enhancing the drug permeability through the cornea, and efficiently delivering the drug to the targeted site. PMID:29491707

Interspinous bursitis is common in polymyalgia rheumatica, but is not associated with spinal pain.

PubMed

Camellino, Dario; Paparo, Francesco; Morbelli, Silvia; Cutolo, Maurizio; Sambuceti, Gianmario; Cimmino, Marco A

2014-12-01

Polymyalgia rheumatica (PMR) is a common inflammatory disease in older people characterized by shoulder and/or pelvic girdle, and cervical and, occasionally, lumbar pain. Interspinous bursitis has been suggested as a potential cause of spinal symptoms. We evaluated, by 18 F-fluorodeoxyglucose (FDG) positron emission tomography integrated with computed tomography (PET/CT), the vertebral structures involved in PMR in a cohort of consecutive, untreated patients. Sixty-five consecutive patients with PMR were studied. After a standardized physical examination, which included evaluation of pain and tenderness in the vertebral column, they underwent FDG-PET/CT. Sites of increased uptake and their correlation with spontaneous and provoked pain were recorded. For comparison, FDG-PET/CT was performed also in 65 age- and sex-matched controls and in 10 rheumatoid arthritis (RA) patients. The most frequent site of spontaneous and provoked pain was the cervical portion. FDG uptake was more frequent in the lumbar portion than at any other location, and in the cervical rather than in the thoracic portion (P <0.0001). No correlation was found between uptake and spontaneous or provoked pain. There was an association between presence of cervical and lumbar bursitis (r = 0.34, P = 0.007). None of the control patients and one out of ten RA patients showed interspinous bursitis. Interspinous bursitis is a frequent finding in the lumbar spine of patients with PMR. However, it is not associated with clinical symptoms and can hardly explain the spinal pain reported by the patients. Cervical pain is more frequent than lumbar pain in PMR patients and may be caused by shoulder girdle involvement.

The Eco-Hydrological Role of Physical Surface Sealing in Dry Environments

NASA Astrophysics Data System (ADS)

Sela, Shai; Svoray, Tal; Assouline, Shmuel

2016-04-01

Soil surface sealing is a widespread natural process in dry environments occurring frequently in bare soil areas between vegetation patches. The low hydraulic conductivity that characterizes the seal layer reduces both infiltration and evaporation fluxes from the soil, and thus has the potential to affect local vegetation water availability and consequently transpiration rates. This effect is investigated here using two separate physically based models - a runoff model, and a root water uptake model. High resolution rainfall data is used to demonstrate the seal layer effect on runoff generation and vegetation water availability, while the seal layer effect on vegetation water uptake is studied using a long-term climatic dataset (44 years) from three dry sites presenting a climatic gradient in the Negev Desert, Israel. The Feddes water uptake parameters for the dominant shrub at the study site (Sarcopoterium spinosum) were acquired using an inverse calibration procedure using data from a lysimeter experiment. The results indicate that the presence of surface sealing increases significantly vegetation water availability through runoff generation. Following water infiltration, the shrub transpiration generally increases if the shrub is surrounded by a seal layer, but this effect can switch from positive to negative depending on initial soil water content, rainfall intensity, and the duration of the subsequent drying intervals. These factors have a marked effect on inter-annual variability of the seal layer effect on the shrub transpiration, which on average was found to be 26% higher under sealed conditions than in the case of unsealed soil surfaces. These results shed light on the importance of surface sealing on the eco-hydrology of dry environments and its contribution to the resilience of woody vegetation.

The binding of [3H]-propylbenzilylcholine mustard by longitudinal muscle strips from guinea-pig small intestine

PubMed Central

Burgen, A.S.V.; Hiley, C.R.; Young, J.M.

1974-01-01

1 The synthesis of tritium labelled propylbenzilylcholine mustard ([3H]-PrBCM; N-2′-chloroethyl-N-[2″, 3″-3H2] propyl-2-aminoethyl benzilate) is described. 2 The uptake by muscle strips was measured and shown to be considerably increased by previous immersion of the muscle in distilled water. 3 A considerable part of the uptake is inhibited selectively by atropine, but not by nicotinic antagonists. A number of muscarinic agonists also inhibit uptake and their apparent affinity constants have been determined. 4 The uptake by atropine-sensitive sites is temperature-insensitive, whereas the other sites are temperature-sensitive. Recovery is highly temperature-sensitive and there is good agreement between recovery of sensitivity to agonists and loss of radioactivity from the muscle. PMID:4150888

Seventeen Sxy-Dependent Cyclic AMP Receptor Protein Site-Regulated Genes Are Needed for Natural Transformation in Haemophilus influenzae

PubMed Central

Mell, Joshua C.; Redfield, Rosemary J.

2012-01-01

Natural competence is the ability of bacteria to actively take up extracellular DNA. This DNA can recombine with the host chromosome, transforming the host cell and altering its genotype. In Haemophilus influenzae, natural competence is induced by energy starvation and the depletion of nucleotide pools. This induces a 26-gene competence regulon (Sxy-dependent cyclic AMP receptor protein [CRP-S] regulon) whose expression is controlled by two regulators, CRP and Sxy. The role of most of the CRP-S genes in DNA uptake and transformation is not known. We have therefore created in-frame deletions of each CRP-S gene and studied their competence phenotypes. All but one gene (ssb) could be deleted. Although none of the remaining CRP-S genes were required for growth in rich medium or survival under starvation conditions, DNA uptake and transformation were abolished or reduced in most of the mutants. Seventeen genes were absolutely required for transformation, with 14 of these genes being specifically required for the assembly and function of the type IV pilus DNA uptake machinery. Only five genes were dispensable for both competence and transformation. This is the first competence regulon for which all genes have been mutationally characterized. PMID:22821979

Seventeen Sxy-dependent cyclic AMP receptor protein site-regulated genes are needed for natural transformation in Haemophilus influenzae.

PubMed

Sinha, Sunita; Mell, Joshua C; Redfield, Rosemary J

2012-10-01

Natural competence is the ability of bacteria to actively take up extracellular DNA. This DNA can recombine with the host chromosome, transforming the host cell and altering its genotype. In Haemophilus influenzae, natural competence is induced by energy starvation and the depletion of nucleotide pools. This induces a 26-gene competence regulon (Sxy-dependent cyclic AMP receptor protein [CRP-S] regulon) whose expression is controlled by two regulators, CRP and Sxy. The role of most of the CRP-S genes in DNA uptake and transformation is not known. We have therefore created in-frame deletions of each CRP-S gene and studied their competence phenotypes. All but one gene (ssb) could be deleted. Although none of the remaining CRP-S genes were required for growth in rich medium or survival under starvation conditions, DNA uptake and transformation were abolished or reduced in most of the mutants. Seventeen genes were absolutely required for transformation, with 14 of these genes being specifically required for the assembly and function of the type IV pilus DNA uptake machinery. Only five genes were dispensable for both competence and transformation. This is the first competence regulon for which all genes have been mutationally characterized.

Recovery of ponderosa pine ecosystem carbon and water fluxes from thinning and stand-replacing fire.

PubMed

Dore, Sabina; Montes-Helu, Mario; Hart, Stephen C; Hungate, Bruce A; Koch, George W; Moon, John B; Finkral, Alex J; Kolb, Thomas E

2012-10-01

Carbon uptake by forests is a major sink in the global carbon cycle, helping buffer the rising concentration of CO 2 in the atmosphere, yet the potential for future carbon uptake by forests is uncertain. Climate warming and drought can reduce forest carbon uptake by reducing photosynthesis, increasing respiration, and by increasing the frequency and intensity of wildfires, leading to large releases of stored carbon. Five years of eddy covariance measurements in a ponderosa pine (Pinus ponderosa)-dominated ecosystem in northern Arizona showed that an intense wildfire that converted forest into sparse grassland shifted site carbon balance from sink to source for at least 15 years after burning. In contrast, recovery of carbon sink strength after thinning, a management practice used to reduce the likelihood of intense wildfires, was rapid. Comparisons between an undisturbed-control site and an experimentally thinned site showed that thinning reduced carbon sink strength only for the first two posttreatment years. In the third and fourth posttreatment years, annual carbon sink strength of the thinned site was higher than the undisturbed site because thinning reduced aridity and drought limitation to carbon uptake. As a result, annual maximum gross primary production occurred when temperature was 3 °C higher at the thinned site compared with the undisturbed site. The severe fire consistently reduced annual evapotranspiration (range of 12-30%), whereas effects of thinning were smaller and transient, and could not be detected in the fourth year after thinning. Our results show large and persistent effects of intense fire and minor and short-lived effects of thinning on southwestern ponderosa pine ecosystem carbon and water exchanges. © 2012 Blackwell Publishing Ltd.

Extracardiac 18F-florbetapir imaging in patients with systemic amyloidosis: more than hearts and minds.

PubMed

Wagner, T; Page, J; Burniston, M; Skillen, A; Ross, J C; Manwani, R; McCool, D; Hawkins, P N; Wechalekar, Ashutosh D

2018-07-01

18 F-Florbetapir has been reported to show cardiac uptake in patients with systemic light-chain amyloidosis (AL). This study systematically assessed uptake of 18 F-florbetapir in patients with proven systemic amyloidosis at sites outside the heart. Seventeen patients with proven cardiac amyloidosis underwent 18 F-florbetapir PET/CT imaging, 15 with AL and 2 with transthyretin amyloidosis (ATTR). Three patients had repeat scans. All patients had protocolized assessment at the UK National Amyloidosis Centre including imaging with 123 I-serum amyloid P component (SAP). 18 F-Florbetapir images were assessed for areas of increased tracer accumulation and time-uptake curves in terms of standardized uptake values (SUV mean ) were produced. All 17 patients showed 18 F-florbetapir uptake at one or more extracardiac sites. Uptake was seen in the spleen in 6 patients (35%; 6 of 9, 67%, with splenic involvement on 123 I-SAP scintigraphy), in the fat in 11 (65%), in the tongue in 8 (47%), in the parotids in 8 (47%), in the masticatory muscles in 7 (41%), in the lungs in 3 (18%), and in the kidney in 2 (12%) on the late half-body images. The 18 F-florbetapir spleen retention index (SRI) was calculated. SRI >0.045 had 100% sensitivity/sensitivity (in relation to 123 I-SAP splenic uptake, the current standard) in detecting splenic amyloid on dynamic imaging and a sensitivity of 66.7% and a specificity of 100% on the late half-body images. Intense lung uptake was seen in three patients, one of whom had lung interstitial infiltration suggestive of amyloid deposition on previous high-resolution CT. Repeat imaging showed a stable appearance in all three patients suggesting no early impact of treatment response. 18 F-Florbetapir PET/CT is a promising tool for the detection of extracardiac sites of amyloid deposition. The combination of uptake in the heart and uptake in the spleen on 18 F-florbetapir PET/CT, a hallmark of AL, suggests that this tracer holds promise as a screening tool for AL.

Ethanol intake and sup 3 H-serotonin uptake II: A study in alcoholic patients using platelets sup 3 H-paroxetine binding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daoust, M.; Boucly, P.; Ernouf, D.

1991-01-01

The kinetic parameters of {sup 3}H-paroxetine binding and {sup 3}H-serotonin uptake were studied in platelets of alcoholic patients. There was no difference between alcoholic and non alcoholic subjects in {sup 3}H-paroxetine binding. When binding and {sup 3}H-serotonin uptake were studied, in the same plasma of the same subjects, the Vmax of serotonin uptake was increased in alcoholics. The data confirm the involvement of serotonin uptake system in alcohol dependance and suggest that serotonin uptake and paroxetine binding sites may be regulated independently in this pathology.

Isolation and characterization of iron chelators from turmeric (Curcuma longa): selective metal binding by curcuminoids.

PubMed

Messner, Donald J; Surrago, Christine; Fiordalisi, Celia; Chung, Wing Yin; Kowdley, Kris V

2017-10-01

Iron overload disorders may be treated by chelation therapy. This study describes a novel method for isolating iron chelators from complex mixtures including plant extracts. We demonstrate the one-step isolation of curcuminoids from turmeric, the medicinal food spice derived from Curcuma longa. The method uses iron-nitrilotriacetic acid (NTA)-agarose, to which curcumin binds rapidly, specifically, and reversibly. Curcumin, demethoxycurcumin, and bisdemethoxycurcumin each bound iron-NTA-agarose with comparable affinities and a stoichiometry near 1. Analyses of binding efficiencies and purity demonstrated that curcuminoids comprise the primary iron binding compounds recovered from a crude turmeric extract. Competition of curcuminoid binding to the iron resin was used to characterize the metal binding site on curcumin and to detect iron binding by added chelators. Curcumin-Iron-NTA-agarose binding was inhibited by other metals with relative potency: (>90% inhibition) Cu 2+  ~ Al 3+  > Zn 2+  ≥ Ca 2+  ~ Mg 2+  ~ Mn 2+ (<20% inhibition). Binding was also inhibited by pharmaceutical iron chelators (desferoxamine or EDTA) or by higher concentrations of weak iron chelators (citrate or silibinin). Investigation of the physiological effects of iron binding by curcumin revealed that curcumin uptake by cultured cells was reduced >80% by addition of iron to the media; uptake was completely restored by desferoxamine. Ranking of metals by relative potencies for blocking curcumin uptake agreed with their relative potencies in blocking curcumin binding to iron-NTA-agarose. We conclude that curcumin can selectively bind toxic metals including iron in a physiological setting, and propose inhibition of curcumin binding to iron-NTA-agarose for iron chelator screening.

Development and characterization of multifunctional nanoparticles for drug delivery to cancer cells

NASA Astrophysics Data System (ADS)

Nahire, Rahul Rajaram

Lipid and polymeric nanoparticles, although proven to be effective drug delivery systems compared to free drugs, have shown considerable limitations pertaining to their uptake and release at tumor sites. Spatial and temporal control over the delivery of anticancer drugs has always been challenge to drug delivery scientists. Here, we have developed and characterized multifunctional nanoparticles (liposomes and polymersomes) which are targeted specifically to cancer cells, and release their contents with tumor specific internal triggers. To enable these nanoparticles to be tracked in blood circulation, we have imparted them with echogenic characteristic. Echogenicity of nanoparticles is evaluated using ultrasound scattering and imaging experiments. Nanoparticles demonstrated effective release with internal triggers such as elevated levels of MMP-9 enzyme found in the extracellular matrix of tumor cells, decreased pH of lysosome, and differential concentration of reducing agents in cytosol of cancer cells. We have also successfully demonstrated the sensitivity of these particles towards ultrasound to further enhance the release with internal triggers. To ensure the selective uptake by folate receptor- overexpressing cancer cells, we decorated these nanoparticles with folic acid on their surface. Fluorescence microscopic images showed significantly higher uptake of folate-targeted nanoparticles by MCF-7 (breast cancer) and PANC-1 (pancreatic cancer) cells compared to particles without any targeting ligand on their surface. To demonstrate the effectiveness of these nanoparticles to carry the drugs inside and kill cancer cells, we encapsulated doxorubicin and/or gemcitabine employing the pH gradient method. Drug loaded nanoparticles showed significantly higher killing of the cancer cells compared to their non-targeted counterparts and free drugs. With further development, these nanoparticles certainly have potential to be used as a multifunctional nanocarriers for image guided, targeted delivery of anticancer drugs.

Deletion of the uracil permease gene confers cross-resistance to 5-fluorouracil and azoles in Candida lusitaniae and highlights antagonistic interaction between fluorinated nucleotides and fluconazole.

PubMed

Gabriel, Frédéric; Sabra, Ayman; El-Kirat-Chatel, Sofiane; Pujol, Sophie; Fitton-Ouhabi, Valérie; Brèthes, Daniel; Dementhon, Karine; Accoceberry, Isabelle; Noël, Thierry

2014-08-01

We characterized two additional membrane transporters (Fur4p and Dal4p) of the nucleobase cation symporter 1 (NCS1) family involved in the uptake transport of pyrimidines and related molecules in the opportunistic pathogenic yeast Candida lusitaniae. Simple and multiple null mutants were constructed by gene deletion and genetic crosses. The function of each transporter was characterized by supplementation experiments, and the kinetic parameters of the uptake transport of uracil were measured using radiolabeled substrate. Fur4p specifically transports uracil and 5-fluorouracil. Dal4p is very close to Fur4p and transports allantoin (glyoxyldiureide). Deletion of the FUR4 gene confers resistance to 5-fluorouracil as well as cross-resistance to triazoles and imidazole antifungals when they are used simultaneously with 5-fluorouracil. However, the nucleobase transporters are not involved in azole uptake. Only fluorinated pyrimidines, not pyrimidines themselves, are able to promote cross-resistance to azoles by both the salvage and the de novo pathway of pyrimidine synthesis. A reinterpretation of the data previously obtained led us to show that subinhibitory doses of 5-fluorocytosine, 5-fluorouracil, and 5-fluorouridine also were able to trigger resistance to fluconazole in susceptible wild-type strains of C. lusitaniae and of different Candida species. Our results suggest that intracellular fluorinated nucleotides play a key role in azole resistance, either by preventing azoles from targeting the lanosterol 14-alpha-demethylase or its catalytic site or by acting as a molecular switch for the triggering of efflux transport. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Contributions of Atmospheric CO and Hydrogen Uptake to Microbial Dynamics on Recent Hawaiian Volcanic Deposits†

PubMed Central

King, Gary M.

2003-01-01

A series of sites were established on Hawaiian volcanic deposits ranging from about 18 to 300 years old. Three sites occurred in areas that supported tropical rain forests; the remaining sites were in areas that supported little or no plant growth. Sites >26 years old consumed atmospheric CO and hydrogen at rates ranging from about 0.2 to 5 mg of CO m−2 day−1 and 0.1 to 4 mg of H2 m−2 day−1, respectively. Respiration, measured as CO2 production, for a subset of the sites ranged from about 40 to >1,400 mg of CO2 m−2 day−1. CO and H2 accounted for about 13 to 25% of reducing equivalent flow for all but a forested site, where neither substrate appeared significant. Based on responses to chloroform fumigation, hydrogen utilization appeared largely due to microbial uptake. In contrast to results for CO and hydrogen, methane uptake occurred consistently only at the forest site. Increasing deposit age was generally accompanied by increasing concentrations of organic matter and microbial biomass, measured as phospholipid phosphate. Exoenzymatic activities (acid and alkaline phosphatases and α- and β-glucosidases) were positively correlated with deposit age in spite of considerable variability within sites. The diversity of substrates utilized in Biolog Ecoplate assays also increased with deposit age, possibly reflecting changes in microbial community complexity. PMID:12839783

Maltose Uptake by the Novel ABC Transport System MusEFGK2I Causes Increased Expression of ptsG in Corynebacterium glutamicum

PubMed Central

Henrich, Alexander; Kuhlmann, Nora; Eck, Alexander W.; Krämer, Reinhard

2013-01-01

The Gram-positive Corynebacterium glutamicum efficiently metabolizes maltose by a pathway involving maltodextrin and glucose formation by 4-α-glucanotransferase, glucose phosphorylation by glucose kinases, and maltodextrin degradation via maltodextrin phosphorylase and α-phosphoglucomutase. However, maltose uptake in C. glutamicum has not been investigated. Interestingly, the presence of maltose in the medium causes increased expression of ptsG in C. glutamicum by an unknown mechanism, although the ptsG-encoded glucose-specific EII permease of the phosphotransferase system itself is not required for maltose utilization. We identified the maltose uptake system as an ABC transporter encoded by musK (cg2708; ATPase subunit), musE (cg2705; substrate binding protein), musF (cg2704; permease), and musG (cg2703; permease) by combination of data obtained from characterization of maltose uptake and reanalyses of transcriptome data. Deletion of the mus gene cluster in C. glutamicum Δmus abolished maltose uptake and utilization. Northern blotting and reverse transcription-PCR experiments revealed that musK and musE are transcribed monocistronically, whereas musF and musG are part of an operon together with cg2701 (musI), which encodes a membrane protein of unknown function with no homologies to characterized proteins. Characterization of growth and [14C]maltose uptake in the musI insertion strain C. glutamicum IMcg2701 showed that musI encodes a novel essential component of the maltose ABC transporter of C. glutamicum. Finally, ptsG expression during cultivation on different carbon sources was analyzed in the maltose uptake-deficient strain C. glutamicum Δmus. Indeed, maltose uptake by the novel ABC transport system MusEFGK2I is required for the positive effect of maltose on ptsG expression in C. glutamicum. PMID:23543710

Effect of Combined 68Ga-PSMAHBED-CC Uptake Pattern and Multiparametric MRI Derived With Simultaneous PET/MRI in the Diagnosis of Primary Prostate Cancer: Initial Experience.

PubMed

Taneja, Sangeeta; Jena, Amarnath; Taneja, Rajesh; Singh, Aru; Ahuja, Aashim

2018-06-01

The purpose of this study is to assess whether temporal changes in 68 Ga-prostate-specific membrane antigen (PSMA)-HBED-CC uptake and multiparametric MRI parameters derived using PET/MRI can aid in characterization of benign and malignant prostate lesions. Thirty-five men with 29 malignant and six benign prostate lesions undergoing complete clinical workup including histologic analysis were enrolled for this retrospective study. All had undergone simultaneous whole-body 68 Ga-PSMAHBED-CC PET/MRI. Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) assessment was made using a 5-point scale showing the likelihood of cancer with the combination of multiparametric MRI findings. Gallium-68-PSMA uptake was recorded at two time points: early (7 minutes) and delayed (54 minutes), adopting a copy-and-paste function of the ROI defined on MR images. ROC curve analysis was performed to test the diagnostic accuracy of early versus delayed PSMA uptake (measured as maximum standardized uptake value [SUV]). A multiple-ROI analysis was done to obtain ROCs for combined PET SUV and multiparametric MRI datasets. Spearman analysis was performed to assess the correlations. There was a significant difference between early and delayed PSMA uptake in malignant prostatic lesions (p < 0.01), which was able to characterize prostate lesions with an AUC of 0.83 and 0.94. Combined ROC analysis of PI-RADSv2 category derived from multiparametric MRI and differential PSMA uptake in characterizing prostatic lesions improved the AUC to 0.99. Dual-phase PSMA uptake improves accuracy of classifying malignant versus benign prostate lesions and complements multiparametric MRI in the diagnosis of prostate cancer.

Spatial analysis of agri-environmental policy uptake and expenditure in Scotland.

PubMed

Yang, Anastasia L; Rounsevell, Mark D A; Wilson, Ronald M; Haggett, Claire

2014-01-15

Agri-environment is one of the most widely supported rural development policy measures in Scotland in terms of number of participants and expenditure. It comprises 69 management options and sub-options that are delivered primarily through the competitive 'Rural Priorities scheme'. Understanding the spatial determinants of uptake and expenditure would assist policy-makers in guiding future policy targeting efforts for the rural environment. This study is unique in examining the spatial dependency and determinants of Scotland's agri-environmental measures and categorised options uptake and payments at the parish level. Spatial econometrics is applied to test the influence of 40 explanatory variables on farming characteristics, land capability, designated sites, accessibility and population. Results identified spatial dependency for each of the dependent variables, which supported the use of spatially-explicit models. The goodness of fit of the spatial models was better than for the aspatial regression models. There was also notable improvement in the models for participation compared with the models for expenditure. Furthermore a range of expected explanatory variables were found to be significant and varied according to the dependent variable used. The majority of models for both payment and uptake showed a significant positive relationship with SSSI (Sites of Special Scientific Interest), which are designated sites prioritised in Scottish policy. These results indicate that environmental targeting efforts by the government for AEP uptake in designated sites can be effective. However habitats outside of SSSI, termed here the 'wider countryside' may not be sufficiently competitive to receive funding in the current policy system. Copyright © 2013 Elsevier Ltd. All rights reserved.

Phenological and physiological mechanisms underlying interannual variability of terrestrial net ecosystem production

NASA Astrophysics Data System (ADS)

Niu, S.; Luo, Y.; Hui, D.; Chen, J.

2013-12-01

The interannual variability (IAV) of atmospheric CO2 concentration varies substantial and is largely ascribed to IAV of terrestrial ecosystem carbon fluxes. However, we have limited understanding on the mechanisms that control the IAV on the carbon flux of terrestrial ecosystems. Here, we hypothesized that physiological and phonological processes regulate IAV significantly in terrestrial carbon uptake (i.e., net ecosystem production, NEP). To test this hypothesis, we analyzed eddy-covariance data from 24 sites with more than 8 years data in deciduous broadleaf forests (DBF), evergreen forests (EF), and grasslands (GRA) in the northern hemisphere. Ecosystem physiology is represented by the maximum carbon uptake capacity (NEPmax) in one year whereas phonology is represented by carbon uptake period (CUP). We found that yearly anomalies of CUP and NEPmax accounted for 40% and 60% separately, and 73% in combination, of the anomalies in annual NEP across all the 253 site-years, with their relative contributions varying among the sites. The IAV of CUP was determined by the anomalies of spring and autumn carbon uptake phenology, both of which were sensitive to climate changes but controlled by different environmental factors in different biomes. IAV of NEPmax was determined by summer precipitation anomalies in DBF and GRA. The results suggest that IAV of NEP is consistently co-determined by CUP and NEPmax anomalies among sites in the northern hemisphere. Overall, the mechanisms revealed by our study on NEP anomalies through changing in phenology and physiology contribute to predictive understanding of temporal dynamics of terrestrial carbon uptake.

Numerical model for the uptake of groundwater contaminants by phreatophytes

USGS Publications Warehouse

Widdowson, M.A.; El-Sayed, A.; Landmeyer, J.E.

2008-01-01

Conventional solute transport models do not adequately account for the effects of phreatophytic plant systems on contaminant concentrations in shallow groundwater systems. A numerical model was developed and tested to simulate threedimensional reactive solute transport in a heterogeneous porous medium. Advective-dispersive transport is coupled to biodegradation, sorption, and plantbased attenuation processes including plant uptake and sorption by plant roots. The latter effects are a function of the physical-chemical properties of the individual solutes and plant species. Models for plant uptake were tested and evaluated using the experimental data collected at a field site comprised of hybrid poplar trees. A non-linear equilibrium isotherm model best represented site conditions.

A molecular recognizing system of serotonin in rat fetal axonal growth cones: uptake and high affinity binding.

PubMed

Mercado, R; Hernández, J

1992-09-18

Axonal growth cone particles (AGCP) isolated from prenatal and postnatal rat brain had different high-affinity 5-HT uptake characteristics. In postnatal AGCP the uptake behaves as in the adult rat brain, while in the prenatal AGCP the uptake characteristics seem to be in a transitional stage. Also in prenatal AGCP we observed specific, high-affinity 5-HT binding sites. These results support the idea of an important role for 5-HT during axogenesis.

Selective Inhibition of K+, Na+, Cl−, and PO43− Uptake in Zea mays L. by Bipolaris (Helminthosporium) maydis Race T Pathotoxin

PubMed Central

Mertz, Stuart M.; Arntzen, Charles J.

1977-01-01

Pathotoxin preparations were obtained from either axenic culture filtrate of race T of Bipolaris maydis (Nisikado) Shoemaker (new culture media and toxin purification procedures are described) or extracts of maize leaves infected with the fungus. The toxins (10−6 to 10−8m) caused inhibition of [86Rb]K+ uptake in leaf discs and apical root segments of Zea mays L. cv W64A Texas (Tcms) and normal (N) cytoplasms. Significant inhibition was measurable as early as 5 min after adding toxin. In Tcms per cent inhibition was increased by increasing toxin concentration and time in toxin, by using solution at pH 5 rather than pH 7, by decreasing external KCl concentration over the range 50 to 0.1 mm (in the presence of 0.5 mm CaSO4), or by exposing leaf discs to light rather than dark during the uptake period in toxin. Root uptake of 22Na+ and 36Cl− was inhibited to a lesser extent than K+. Inhibition of 32PO43− uptake occurred after 40 min when cyclosis had ceased. When combined with data in the literature, our data indicate that the plasmalemma is the probable primary site of toxin action in N and Tcms maize. Comparison of the effects of toxin on K+ uptake in N and Tcms maize suggests the existence of more than one mode of toxin action: a weak disruptive effect in N and Tcms, and in addition, specific membrane sites in Tcms involved in monovalent ion uptake. Six genotypes in N or Tcms cytoplasm which exhibited different degrees of disease susceptibility in the field showed a corresponding gradation of susceptibility to the toxin when a K+ uptake bioassay was used. This correlation is strong evidence that the sites of toxin action affecting K+ transport have characteristics closely related to cellular factors regulating susceptibility to fungal attack. PMID:16660094

An assessment of health risks associated with arsenic exposure via consumption of homegrown vegetables near contaminated glassworks sites.

PubMed

Uddh-Söderberg, Terese E; Gunnarsson, Sara J; Hogmalm, K Johan; Lindegård, M I Boel G; Augustsson, Anna L M

2015-12-01

The health risk posed by arsenic in vegetables grown in private gardens near 22 contaminated glassworks sites was investigated in this study. Firstly, vegetable (lettuce and potato) and soil samples were collected and arsenic concentrations measured to characterize the arsenic uptake in the selected crops. Secondly, a probabilistic exposure assessment was conducted to estimate the average daily intake (ADIveg), which was then evaluated against toxicological reference values by the calculation of hazard quotients (HQs) and cancer risks (CRs). The results show that elevated arsenic concentrations in residential garden soils are mirrored by elevated concentrations in vegetables, and that consumption of these vegetables alone may result in an unacceptable cancer risk; the calculated reasonable maximum exposure, for example, corresponded to a cancer incidence 20 times higher than the stated tolerance limit. However, the characterization of risk depends to a great extent on which toxicological reference value is used for comparison, as well as how the exposure is determined. Based on the assumptions made in the present study, the threshold levels for chronic non-carcinogenic or acute effects were not exceeded, but the cancer risks indicated highlight the need for further exposure studies, as dietary intake involves more than just homegrown vegetables and total exposure is a function of more than just one exposure pathway. In addition, glassworks sites--and contaminated sites in general--contain multiple contaminants, affecting the final and total risk. Copyright © 2015. Published by Elsevier B.V.

Mechanism of potassium ion uptake by the Na+/K+-ATPase

PubMed Central

Castillo, Juan P.; Rui, Huan; Basilio, Daniel; Das, Avisek; Roux, Benoît; Latorre, Ramon; Bezanilla, Francisco; Holmgren, Miguel

2015-01-01

The Na+/K+-ATPase restores sodium (Na+) and potassium (K+) electrochemical gradients dissipated by action potentials and ion-coupled transport processes. As ions are transported, they become transiently trapped between intracellular and extracellular gates. Once the external gate opens, three Na+ ions are released, followed by the binding and occlusion of two K+ ions. While the mechanisms of Na+ release have been well characterized by the study of transient Na+ currents, smaller and faster transient currents mediated by external K+ have been more difficult to study. Here we show that external K+ ions travelling to their binding sites sense only a small fraction of the electric field as they rapidly and simultaneously become occluded. Consistent with these results, molecular dynamics simulations of a pump model show a wide water-filled access channel connecting the binding site to the external solution. These results suggest a mechanism of K+ gating different from that of Na+ occlusion. PMID:26205423

Preparation and in vivo/in vitro evaluation of formononetin phospholipid/vitamin E TPGS micelles.

PubMed

Cheng, Xudong; Yan, Hongmei; Jia, Xiaobin; Zhang, Zhenhai

2016-01-01

To enhance the formononetin (FN) antitumor effect, we developed a passive targeting FN-contained formulation. FN-contained Vitamin E d-α-tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS or TPGS)/phospholipid micelles were prepared by the solvent injection method. Particle size, polydispersity, zeta potential, encapsulation efficiency, drug release profile, and micelles morphology were evaluated and characterized by various methods including high-performance liquid chromatography, dynamic light scattering, and transmission electron microscopy. Cellular uptake of micelles was evaluated with fluorescence imaging coupled with HPLC method. Cytotoxicity of FN micelles and free FN was compared using MTT method. In vivo imaging was employed to assess the accumulation of DiR micelles and free DiR at tumor site. The antitumor effect of FN micelles was examined in tumor-bearing mice. The results showed that prepared FN micelles had an average particle diameter of 111.91 ± 5.82 nm with good stability. FN micelles enhanced the cellular uptake and improved cell cytotoxicity than free FN. Furthermore, DiR micelles quickly accumulated at the tumor site than free DiR. FN micelles significantly improved tumor inhibition rate compared to that observed with free FN in tumor-bearing mice with great biosafety. Thus, FN micelles demonstrated a clear treatment advantage and provided an ideal drug administration system to improve the antitumor effect of FN.

Significant enhancement of gas uptake capacity and selectivity via the judicious increase of open metal sites and Lewis basic sites within two polyhedron-based metal-organic frameworks.

PubMed

Liu, Bing; Yao, Shuo; Shi, Chao; Li, Guanghua; Huo, Qisheng; Liu, Yunling

2016-02-21

Two new isomorphous polyhedron-based MOFs ( and ), with dual functionalities of OMSs and LBSs, have been synthesized by using the SBB strategy. By judiciously avoiding the DABCO axial ligand, possesses more OMSs than , and exhibits a significant enhancement of CO2 uptake capacity 210 versus 162 cm(3) g(-1) for at 273 K under 1 bar.

Native Plant Uptake Model for Radioactive Waste Disposal Areas at the Nevada Test Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

BROWN,THERESA J.; WIRTH,SHARON

1999-09-01

This report defines and defends the basic framework, methodology, and associated input parameters for modeling plant uptake of radionuclides for use in Performance Assessment (PA) activities of Radioactive Waste Management Sites (RWMS) at the Nevada Test Site (NTS). PAs are used to help determine whether waste disposal configurations meet applicable regulatory standards for the protection of human health, the environment, or both. Plants adapted to the arid climate of the NTS are able to rapidly capture infiltrating moisture. In addition to capturing soil moisture, plant roots absorb nutrients, minerals, and heavy metals, transporting them within the plant to the above-groundmore » biomass. In this fashion, plant uptake affects the movement of radionuclides. The plant uptake model presented reflects rooting characteristics important to plant uptake, biomass turnover rates, and the ability of plants to uptake radionuclides from the soil. Parameters are provided for modeling plant uptake and estimating surface contaminant flux due to plant uptake under both current and potential future climate conditions with increased effective soil moisture. The term ''effective moisture'' is used throughout this report to indicate the soil moisture that is available to plants and is intended to be inclusive of all the variables that control soil moisture at a site (e.g., precipitation, temperature, soil texture, and soil chemistry). Effective moisture is a concept used to simplify a number of complex, interrelated soil processes for which there are too little data to model actual plant available moisture. The PA simulates both the flux of radionuclides across the land surface and the potential dose to humans from that flux. Surface flux is modeled here as the amount of soil contamination that is transferred from the soil by roots and incorporated into aboveground biomass. Movement of contaminants to the surface is the only transport mechanism evaluated with the model presented here. Parameters necessary for estimating surface contaminant flux due to native plants expected to inhabit the NTS RWMSS are developed in this report. The model is specific to the plant communities found at the NTS and is designed for both short-term (<1,000 years) and long-term (>1,000 years) modeling efforts. While the model has been crafted for general applicability to any NTS PA, the key radionuclides considered are limited to the transuranic (TRU) wastes disposed of at the NTS.« less

Uptake of Free Choline by Isolated Perfused Rat Liver

NASA Astrophysics Data System (ADS)

Zeisel, Steven H.; Story, David L.; Wurtman, Richard J.; Brunengraber, Henri

1980-08-01

The uptake of free choline by isolated perfused rat liver was characterized. A saturable uptake mechanism [Ka=0.17± 0.07 mM (SD); Vmax=0.84± 0.16\\ μ mol/min × g dry weight] and a nonsaturable mechanism (through which uptake is proportional to choline concentration in the perfusate) were identified. Most of the choline transported into hepatocytes was converted to betaine, phosphorylcholine, or lecithin. Free choline also accumulated within the intracellular space, suggesting that choline oxidase activity does not always limit choline's uptake by the liver.

Axillary lymph node uptake of technetium-99m-MDP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ongseng, F.; Goldfarb, C.R.; Finestone, H.

We sought to determine the frequency and significance of axillary lymph node visualization on bone scans performed with diphosphonates. Consecutive {sup 99m}Tc-methylene diphosphonate ({sup 99m}Tc-MDP) bone scans (2435) were inspected for axillary soft-tissue uptake. In positive cases, the results of physical examination, correlative imaging studies and serial bone scans were recorded, as was the site of venipuncture. Forty-eight studies (2%) showed axillary uptake ipsilateral to the injection site. Extravasation of tracer, documented by focal activity near the injection site, was present in every case. There was no association with axillary adenopathy, mass, induration of radiographically visible calcification. On some images,more » foci adjacent to the axilla were superimposed on the rib, scapula, or humerus. The bone-to-background ratio was frequently reduced; repeat imaging after 1-2 hr usually improved osseous detail. Ipsilateral axillary lymph node visualization due to extravasation of {sup 99m}Tc-MDP is frequently associated with additional foci superimposed on osseous structures simulating pathology. Delayed skeletal uptake is common in such cases and necessitates a greater time interval between injection and imaging. 7 refs., 3 figs.« less

Investigation of Heterogeneous N2O5 Uptake and ClNO2 Yield at a Rural and a Mountain-top Site in Northern China

NASA Astrophysics Data System (ADS)

Wang, Z.; Tham, Y. J.; Wang, W.; LI, Q.; Yun, H.; Wang, X.; Xue, L.; Wang, T.

2017-12-01

Dinitrogen pentoxide (N2O5) is a reactive intermediate in the atmospheric oxidation of nitrogen oxides (NOx), and its heterogeneous reaction plays key roles in the chemical transformation and removal of NOx, as well as the production of nitrate and nitryl chloride (ClNO2) that affects the radical budget and photochemical ozone formation. Ambient measurements at a rural site and a mountain top site in northern China in the summer of 2014 revealed significant ClNO2 mixing ratios (up to 2.1 ppbv) produced by fast heterogeneous N2O5 uptake on atmospheric aerosols. Frequently intercepted ClNO2-laden plumes at the mountain site indicate significant ClNO2 production occurred in the nocturnal residual layer, and could help explain the sustained ClNO2 peaks after sunrise observed in the ground site in the region. The meteorological and chemical analysis suggested that elevated ClNO2 plumes were mostly associated with nocturnal buoyant emission from point combustion sources, such as power and industry plants. The uptake coefficients (γ) of N2O5 and yields (ϕ) of ClNO2 were then derived for different plumes observed at the ground and mountain sites, and the factors affecting the variability of γ and ϕ under different conditions were also investigated. The uptake coefficients and yields obtained in this study in northern China will be compared with other observations in the world, and also compared to the existing parameterizations based on aerosol compositions. The contribution of fast N2O5 heterogeneous reaction to the nocturnal NOx processing and nitrate aerosol formation will be further examined, to better understand the impacts of heterogeneous reactive nitrogen chemistry on air quality in northern China.

Forest canopy uptake of atmospheric nitrogen deposition at eastern U.S. conifer sites: Carbon storage implications?

Treesearch

Herman Sievering; Ivan Fernandez; John Lee; John Hom; Lindsey Rustad

2000-01-01

Dry deposition determinations, along with wet deposition and throughfall (TF) measurements, at a spruce fir forest in central Maine were used to estimate the effect of atmospherically deposited nitrogen (N) uptake on forest carbon storage. Using nitric acid and particulate N as well as TF ammonium and nitrate data, the growing season (May-October) net canopy uptake of...

Water uptake by two river red gum ( Eucalyptus camaldulensis) clones in a discharge site plantation in the Western Australian wheatbelt

NASA Astrophysics Data System (ADS)

Marshall, John K.; Morgan, Anne L.; Akilan, Kandia; Farrell, Richard C. C.; Bell, David T.

1997-12-01

The heat-pulse technique was used to estimate year-long water uptake in a discharge zone plantation of 9-year-old clonal Eucalyptus camaldulensis Dehnh. near Wubin, Western Australia. Water uptake matched rainfall closely during weter months but exceeded rainfall as the dry season progressed. Average annual water uptake (1148 mm) exceeded rainfall (432 mm) by about 2.7 fold and approached 56% of pan evaporation for the area. The data suggest that at least 37% (i.e. ( {1}/{2.7}) × 100 ) of the lower catchment discharge zone should be planted to prevent the rise of groundwater. Water uptake varied with soil environment, season and genotype. Upslope trees used more water than did downslope trees. Water uptake was higher in E. camaldulensis clone M80 than in clone M66 until late spring. The difference reversed as summer progressed. Both clones, however, have the potential to dry out the landscape when potential evapotranspiration exceeds rainfall. This variation in water uptake within the species indicates the potential for manipulating plantation uptake by matching tree characteristics to site characteristics. Controlled experiments on the heat-pulse technique indicated accuracy errors of approximately 10%. This, combined with the ability to obtain long-term, continuous data and the superior logistics of use of the heat-pulse technique, suggests that results obtained by it would be much more reliable than those achieved by the ventilated chamber technique.

Characterization of endocytosis and exocytosis of cationic nanoparticles in airway epithelium cells

NASA Astrophysics Data System (ADS)

Youta Dombu, Christophe; Kroubi, Maya; Zibouche, Rima; Matran, Regis; Betbeder, Didier

2010-09-01

A major challenge of drug delivery using colloids via the airway is to understand the mechanism implied in their interactions with epithelial cells. The purpose of this work was to characterize the process of endocytosis and exocytosis of cationic nanoparticles (NPs) made of maltodextrin which were developed as a delivery system for antigens in vaccine applications. Confocal microscopy demonstrated that these NP are rapidly endocytosed after as little as 3 min incubation, and that the endocytosis was also faster than NP binding since most of the NPs were found in the middle of the cells around the nuclei. A saturation limit was observed after a 40 min incubation, probably due to an equilibrium becoming established between endocytosis and exocytosis. Endocytosis was dramatically reduced at 4 °C compared with 37 °C, or by NaN3 treatment, both results suggesting an energy dependent process. Protamine pretreatment of the cells inhibited NPs uptake and we found that clathrin pathway is implied in their endocytosis. Cholesterol depletion increased NP uptake by 300% and this phenomenon was explained by the fact that cholesterol depletion totally blocked NP exocytosis. These results suggest that these cationic NPs interact with anionic sites, are quickly endocytosed via the clathrin pathway and that their exocytosis is cholesterol dependent, and are similar to those obtained in other studies with viruses such as influenza.

Evaluation of folate conjugated superparamagnetic iron oxide nanoparticles for scintigraphic/magnetic resonance imaging.

PubMed

Chauhan, Ram Prakash; Mathur, Rashi; Singh, Gurjaspreet; Kaul, Ankur; Bag, Narmada; Singh, Sweta; Kumar, Hemanth; Patra, Manoj; Mishra, Anil K

2013-03-01

The physical and chemical properties of the nanoparticles influence their pharmacokinetics and ability to accumulate in tumors. In this paper we report a facile method to conjugate folic acid molecule to iron oxide nanoparticles to increase the specific uptake of these nanoparticles by the tumor, which will be useful in targeted imaging of the tumor. The iron oxide nanoparticles were synthesized by alkaline co precipitation method and were surface modified with dextranto make them stable. The folic acid is conjugated to the dextran modified iron oxide nanoparticles by reductive amination process after the oxidation of the dextran with periodate. The synthesized folic acid conjugated nanoparticles were characterized for size, phase, morphology and magnetization by using various physicochemical characterization techniques such as transmission electron microscopy, X-ray diffraction, fourier transform infrared spectroscopy, vibrating sample magnetometry, dynamic light scattering and zetasizer etc. The quantification of the generated carbonyl groups and folic acid conjugated to the surface of the magnetic nanoparticles was done by colorimetric estimations using UV-Visible spectroscopy. The in vitro MR studies were carried out over a range of concentrations and showed significant shortening of the transverse relaxation rate, showing the ability of the nanoconjugate to act as an efficient probe for MR imaging. The biodistribution studies and the scintigraphy done by radiolabeling the nanoconjugate with 99mTc show the enhanced uptake at the tumor site showing its enhanced specificity.

Characterization of the homologs of flerovium with crown ether based extraction chromatography resins: studies in nitric acid

DOE PAGES

Despotopulos, John D.; Kmak, Kelly N.; Gharibyan, Narek; ...

2016-09-17

Eichrom’s Pb resin, a crown-ether-based extraction chromatography resin, was characterized for separation of the flerovium (Fl) homologs, Pb and Sn. Batch uptake of Pb(II) and Sn(IV) radionuclides was determined from an HNO 3 matrix. Pb(II) was strongly retained on the resin at all HNO 3 concentrations, while Sn(IV) showed no uptake. Extraction kinetics for Pb(II) were examined and show suitable uptake on the second time scale. Here, separation methods for the isolation of individual homologs, Pb(II) and Sn(IV), have been established using 2 mL pre-packed vacuum flow Pb resin columns.

Carbon availability for the fungus triggers nitrogen uptake and transport in the arbuscular mycorrhizal symbiosis

USDA-ARS?s Scientific Manuscript database

The arbuscular mycorrhizal (AM) symbiosis is characterized by a transfer of nutrients in exchange for carbon. We tested the effect of the carbon availability for the AM fungus Glomus intraradices on nitrogen (N) uptake and transport in the symbiosis. We followed the uptake and transport of 15N and ...

The 'glial' glutamate transporter, EAAT2 (Glt-1) accounts for high affinity glutamate uptake into adult rodent nerve endings.

PubMed

Suchak, Sachin K; Baloyianni, Nicoletta V; Perkinton, Michael S; Williams, Robert J; Meldrum, Brian S; Rattray, Marcus

2003-02-01

The excitatory amino acid transporters (EAAT) removes neurotransmitters glutamate and aspartate from the synaptic cleft. Most CNS glutamate uptake is mediated by EAAT2 into glia, though nerve terminals show evidence for uptake, through an unknown transporter. Reverse-transcriptase PCR identified the expression of EAAT1, EAAT2, EAAT3 and EAAT4 mRNAs in primary cultures of mouse cortical or striatal neurones. We have used synaptosomes and glial plasmalemmal vesicles (GPV) from adult mouse and rat CNS to identify the nerve terminal transporter. Western blotting showed detectable levels of the transporters EAAT1 (GLAST) and EAAT2 (Glt-1) in both synaptosomes and GPVs. Uptake of [3H]D-aspartate or [3H]L-glutamate into these preparations revealed sodium-dependent uptake in GPV and synaptosomes which was inhibited by a range of EAAT blockers: dihydrokainate, serine-o-sulfate, l-trans-2,4-pyrrolidine dicarboxylate (PDC) (+/-)-threo-3-methylglutamate and (2S,4R )-4-methylglutamate. The IC50 values found for these compounds suggested functional expression of the 'glial, transporter, EAAT2 in nerve terminals. Additionally blockade of the majority EAAT2 uptake sites with 100 micro m dihydrokainate, failed to unmask any functional non-EAAT2 uptake sites. The data presented in this study indicate that EAAT2 is the predominant nerve terminal glutamate transporter in the adult rodent CNS.

Response of antioxidant enzymes in Nicotiana tabacum clones during phytoextraction of heavy metals.

PubMed

Lyubenova, Lyudmila; Nehnevajova, Erika; Herzig, Rolf; Schröder, Peter

2009-07-01

Tobacco, Nicotiana tabacum, is a widely used model plant for growth on heavy-metal-contaminated sites. Its high biomass and deep rooting system make it interesting for phytoextraction. In the present study, we investigated the antioxidative activities and glutathione-dependent enzymes of different tobacco clones optimized for better Cd and Zn accumulation in order to characterize their performance in the field. The improved heavy metal resistance also makes the investigated tobacco clones interesting for understanding the plant defense enzyme system in general. Freshly harvested plant material (N. tabacum leaves) was used to investigate the antioxidative cascade in plants grown on heavy metal contaminated sites with and without amendments of different ammonium nitrate and ammonium sulfate fertilizers. Plants were grown on heavily polluted soils in north-east Switzerland. Leaves were harvested at the field site and directly deep frozen in liquid N(2). Studies were concentrated on the antioxidative enzymes of the Halliwell-Asada cycle, and spectrophotometric measurements of catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11), superoxide dismutase (SOD, EC 1.15.1.1), glutathione peroxidase (GPX, EC 1.11.1.9), glutathione reductase (GR, EC 1.6.4.2), glutathione S-transferase (GST, EC 2.5.1.18) were performed. We tried to explain the relationship between fertilizer amendments and the activity of the enzymatic defense systems. When tobacco (N. tabacum) plants originating from different mutants were grown under field conditions with varying fertilizer application, the uptake of cadmium and zinc from soil increased with increasing biomass. Depending on Cd and Zn uptake, several antioxidant enzymes showed significantly different activities. Whereas SOD and CAT were usually elevated, several other enzymes, and isoforms of GST were strongly inhibited. Heavy metal uptake represents severe stress to plants, and specific antioxidative enzymes are induced at the cost of more general reactions of the Halliwell-Asada cycle. In well-supplied plants, the glutathione level remains more or less unchanged. The lack of certain glutathione S-transferases upon exposure to heavy metals might be problematic in cases when organic pollutants coincide with heavy metal pollution. When planning phytoremediation of sites, mixed pollution scenarios have to be foreseen and plants should be selected according to both, their stress resistance and hyperaccumulative capacity.

Studies on hydrogenase

PubMed Central

YAGI, Tatsuhiko; HIGUCHI, Yoshiki

2013-01-01

Hydrogenases are microbial enzymes which catalyze uptake and production of H2. Hydrogenases are classified into 10 classes based on the electron carrier specificity, or into 3 families, [NiFe]-family (including [NiFeSe]-subfamily), [FeFe]-family and [Fe]-family, based on the metal composition of the active site. H2 is heterolytically cleaved on the enzyme (E) to produce EHaHb, where Ha and Hb have different rate constants for exchange with the medium hydron. X-ray crystallography unveiled the three-dimensional structures of hydrogenases. The simplest [NiFe]-hydrogenase is a heterodimer, in which the large subunit bears the Ni-Fe center buried deep in the protein, and the small subunit bears iron-sulfur clusters, which mediate electron transfer between the Ni-Fe center and the protein surface. Some hydrogenases have additional subunit(s) for interaction with their electron carriers. Various redox states of the enzyme were characterized by EPR, FTIR, etc. Based on the kinetic, structural and spectroscopic studies, the catalytic mechanism of [NiFe]-hydrogenase was proposed to explain H2-uptake, H2-production and isotopic exchange reactions. PMID:23318679

Nutrient uptake by agricultural crops from biochar-amended soils: results from two field experiments in Austria

NASA Astrophysics Data System (ADS)

Karer, Jasmin; Zehetner, Franz; Kloss, Stefanie; Wimmer, Bernhard; Soja, Gerhard

2013-04-01

The use of biochar as soil amendment is considered as a promising agricultural soil management technique, combining carbon sequestration and soil fertility improvements. These expectations are largely founded on positive experiences with biochar applications to impoverished or degraded tropical soils. The validity of these results for soils in temperate climates needs confirmation from field experiments with typical soils representative for intensive agricultural production areas. Frequently biochar is mixed with other organic additives like compost. As these two materials interact with each other and each one may vary considerably in its basic characteristics, it is difficult to attribute the effects of the combined additive to one of its components and to a specific physico-chemical parameter. Therefore investigations of the amendment efficacy require the study of the pure components to characterize their specific behavior in soil. This is especially important for adsorption behavior of biochar for macro- and micronutrients because in soil there are multiple nutrient sinks that compete with plant roots for vital elements. Therefore this contribution presents results from a field amendment study with pure biochar that had the objective to characterize the macro- and microelement uptake of crops from different soils in two typical Austrian areas of agricultural production. At two locations in North and South-East Austria, two identical field experiments on different soils (Chernozem and Cambisol) were installed in 2011 with varying biochar additions (0, 30 and 90 t/ha) and two nitrogen levels. The biochar was a product from slow pyrolysis of wood (SC Romchar SRL). During the installation of the experiments, the biochar fraction of <2 mm was mixed with surface soil to a depth of 15 cm in plots of 33 m2 each (n=4). Barley (at the Chernozem soil) and maize (at the Cambisol) were cultivated according to standard agricultural practices. The highest crop yields at both study sites were observed after a biochar application rate of 90 t/ha and an abundant nitrogen supply (mineral N fertilizer rates: 120 kg/ha for barley, 150 kg/ha for corn). An omission of biochar addition at the same nitrogen addition rate resulted in a yield decrease of 10 % for barley although the total N uptake was 11 % higher but P and K uptake decreased by 14 and 6 %. This indicates that the higher yields with biochar were accompanied by increased availability of P and K but not N. The N deficiency treatment (with biochar amendment) resulted in yield decreases of 23 %, which were similar as the reductions of N uptake while reductions of P and K uptake were less pronounced. For corn, the omission of biochar caused only marginal yield effects (6%) and no significant changes in the N, P, and K uptake rates. Deficient N supply, however, resulted in severe yield reductions (46%) in spite of the high biochar application rate. The reductions of macronutrient uptake were in the same range for N (44%) but lower for P, K, Ca and Mg (19 to 33%). In summary, N and Cu were the elements that were least available for plant uptake at high biochar application rates.

Self-assembled silk sericin/poloxamer nanoparticles as nanocarriers of hydrophobic and hydrophilic drugs for targeted delivery

NASA Astrophysics Data System (ADS)

Mandal, Biman B.; Kundu, S. C.

2009-09-01

In recent times self-assembled micellar nanoparticles have been successfully employed in tissue engineering for targeted drug delivery applications. In this review, silk sericin protein from non-mulberry Antheraea mylitta tropical tasar silk cocoons was blended with pluronic F-127 and F-87 in the presence of solvents to achieve self-assembled micellar nanostructures capable of carrying both hydrophilic (FITC-inulin) and hydrophobic (anticancer drug paclitaxel) drugs. The fabricated nanoparticles were subsequently characterized for their size distribution, drug loading capability, cellular uptake and cytotoxicity. Nanoparticle sizes ranged between 100 and 110 nm in diameter as confirmed by dynamic light scattering. Rapid uptake of these particles into cells was observed in in vitro cellular uptake studies using breast cancer MCF-7 cells. In vitro cytotoxicity assay using paclitaxel-loaded nanoparticles against breast cancer cells showed promising results comparable to free paclitaxel drugs. Drug-encapsulated nanoparticle-induced apoptosis in MCF-7 cells was confirmed by FACS and confocal microscopic studies using Annexin V staining. Up-regulation of pro-apoptotic protein Bax, down-regulation of anti-apoptotic protein Bcl-2 and cleavage of regulatory protein PARP through Western blot analysis suggested further drug-induced apoptosis in cells. This study projects silk sericin protein as an alternative natural biomaterial for fabrication of self-assembled nanoparticles in the presence of poloxamer for successful delivery of both hydrophobic and hydrophilic drugs to target sites.

Self-assembled silk sericin/poloxamer nanoparticles as nanocarriers of hydrophobic and hydrophilic drugs for targeted delivery.

PubMed

Mandal, Biman B; Kundu, S C

2009-09-02

In recent times self-assembled micellar nanoparticles have been successfully employed in tissue engineering for targeted drug delivery applications. In this review, silk sericin protein from non-mulberry Antheraea mylitta tropical tasar silk cocoons was blended with pluronic F-127 and F-87 in the presence of solvents to achieve self-assembled micellar nanostructures capable of carrying both hydrophilic (FITC-inulin) and hydrophobic (anticancer drug paclitaxel) drugs. The fabricated nanoparticles were subsequently characterized for their size distribution, drug loading capability, cellular uptake and cytotoxicity. Nanoparticle sizes ranged between 100 and 110 nm in diameter as confirmed by dynamic light scattering. Rapid uptake of these particles into cells was observed in in vitro cellular uptake studies using breast cancer MCF-7 cells. In vitro cytotoxicity assay using paclitaxel-loaded nanoparticles against breast cancer cells showed promising results comparable to free paclitaxel drugs. Drug-encapsulated nanoparticle-induced apoptosis in MCF-7 cells was confirmed by FACS and confocal microscopic studies using Annexin V staining. Up-regulation of pro-apoptotic protein Bax, down-regulation of anti-apoptotic protein Bcl-2 and cleavage of regulatory protein PARP through Western blot analysis suggested further drug-induced apoptosis in cells. This study projects silk sericin protein as an alternative natural biomaterial for fabrication of self-assembled nanoparticles in the presence of poloxamer for successful delivery of both hydrophobic and hydrophilic drugs to target sites.

[MoS4]2- Cluster Bridges in Co-Fe Layered Double Hydroxides for Mercury Uptake from S-Hg Mixed Flue Gas.

PubMed

Xu, Haomiao; Yuan, Yong; Liao, Yong; Xie, Jiangkun; Qu, Zan; Shangguan, Wenfeng; Yan, Naiqiang

2017-09-05

[MoS 4 ] 2- clusters were bridged between CoFe layered double hydroxide (LDH) layers using the ion-exchange method. [MoS 4 ] 2- /CoFe-LDH showed excellent Hg 0 removal performance under low and high concentrations of SO 2 , highlighting the potential for such material in S-Hg mixed flue gas purification. The maximum mercury capacity was as high as 16.39 mg/g. The structure and physical-chemical properties of [MoS 4 ] 2- /CoFe-LDH composites were characterized with FT-IR, XRD, TEM&SEM, XPS, and H 2 -TPR. [MoS 4 ] 2- clusters intercalated into the CoFe-LDH layered sheets; then, we enlarged the layer-to-layer spacing (from 0.622 to 0.880 nm) and enlarged the surface area (from 41.4 m 2 /g to 112.1 m 2 /g) of the composite. During the adsorption process, the interlayer [MoS 4 ] 2- cluster was the primary active site for mercury uptake. The adsorbed mercury existed as HgS on the material surface. The absence of active oxygen results in a composite with high sulfur resistance. Due to its high efficiency and SO 2 resistance, [MoS 4 ] 2- /CoFe-LDH is a promising adsorbent for mercury uptake from S-Hg mixed flue gas.

Carbon and water fluxes from ponderosa pine forests disturbed by wildfire and thinning.

PubMed

Dore, S; Kolb, T E; Montes-Helu, M; Eckert, S E; Sullivan, B W; Hungate, B A; Kaye, J P; Hart, S C; Koch, G W; Finkral, A

2010-04-01

Disturbances alter ecosystem carbon dynamics, often by reducing carbon uptake and stocks. We compared the impact of two types of disturbances that represent the most likely future conditions of currently dense ponderosa pine forests of the southwestern United States: (1) high-intensity fire and (2) thinning, designed to reduce fire intensity. High-severity fire had a larger impact on ecosystem carbon uptake and storage than thinning. Total ecosystem carbon was 42% lower at the intensely burned site, 10 years after burning, than at the undisturbed site. Eddy covariance measurements over two years showed that the burned site was a net annual source of carbon to the atmosphere whereas the undisturbed site was a sink. Net primary production (NPP), evapotranspiration (ET), and water use efficiency were lower at the burned site than at the undisturbed site. In contrast, thinning decreased total ecosystem carbon by 18%, and changed the site from a carbon sink to a source in the first posttreatment year. Thinning also decreased ET, reduced the limitation of drought on carbon uptake during summer, and did not change water use efficiency. Both disturbances reduced ecosystem carbon uptake by decreasing gross primary production (55% by burning, 30% by thinning) more than total ecosystem respiration (TER; 33-47% by burning, 18% by thinning), and increased the contribution of soil carbon dioxide efflux to TER. The relationship between TER and temperature was not affected by either disturbance. Efforts to accurately estimate regional carbon budgets should consider impacts on carbon dynamics of both large disturbances, such as high-intensity fire, and the partial disturbance of thinning that is often used to prevent intense burning. Our results show that thinned forests of ponderosa pine in the southwestern United States are a desirable alternative to intensively burned forests to maintain carbon stocks and primary production.

The pitcher plant Sarracenia purpurea can directly acquire organic nitrogen and short-circuit the inorganic nitrogen cycle.

PubMed

Karagatzides, Jim D; Butler, Jessica L; Ellison, Aaron M

2009-07-07

Despite the large stocks of organic nitrogen in soil, nitrogen availability limits plant growth in many terrestrial ecosystems because most plants take up only inorganic nitrogen, not organic nitrogen. Although some vascular plants can assimilate organic nitrogen directly, only recently has organic nitrogen been found to contribute significantly to the nutrient budget of any plant. Carnivorous plants grow in extremely nutrient-poor environments and carnivory has evolved in these plants as an alternative pathway for obtaining nutrients. We tested if the carnivorous pitcher plant Sarracenia purpurea could directly take up intact amino acids in the field and compared uptake of organic and inorganic forms of nitrogen across a gradient of nitrogen deposition. We hypothesized that the contribution of organic nitrogen to the nitrogen budget of the pitcher plant would decline with increasing nitrogen deposition. At sites in Canada (low nitrogen deposition) and the United States (high nitrogen deposition), individual pitchers were fed two amino acids, glycine and phenylalanine, and inorganic nitrogen (as ammonium nitrate), individually and in mixture. Plants took up intact amino acids. Acquisition of each form of nitrogen provided in isolation exceeded uptake of the same form in mixture. At the high deposition site, uptake of organic nitrogen was higher than uptake of inorganic nitrogen. At the low deposition site, uptake of all three forms of nitrogen was similar. Completeness of the associated detritus-based food web that inhabits pitcher-plant leaves and breaks down captured prey had no effect on nitrogen uptake. By taking up intact amino acids, Sarracenia purpurea can short-circuit the inorganic nitrogen cycle, thus minimizing potential bottlenecks in nitrogen availability that result from the plant's reliance for nitrogen mineralization on a seasonally reconstructed food web operating on infrequent and irregular prey capture.

Linking activity, composition and seasonal dynamics of atmospheric methane oxidizers in a meadow soil

PubMed Central

Shrestha, Pravin Malla; Kammann, Claudia; Lenhart, Katharina; Dam, Bomba; Liesack, Werner

2012-01-01

Microbial oxidation is the only biological sink for atmospheric methane. We assessed seasonal changes in atmospheric methane oxidation and the underlying methanotrophic communities in grassland near Giessen (Germany), along a soil moisture gradient. Soil samples were taken from the surface layer (0–10 cm) of three sites in August 2007, November 2007, February 2008 and May 2008. The sites showed seasonal differences in hydrological parameters. Net uptake rates varied seasonally between 0 and 70 μg CH4 m−2 h−1. Greatest uptake rates coincided with lowest soil moisture in spring and summer. Over all sites and seasons, the methanotrophic communities were dominated by uncultivated methanotrophs. These formed a monophyletic cluster defined by the RA14, MHP and JR1 clades, referred to as upland soil cluster alphaproteobacteria (USCα)-like group. The copy numbers of pmoA genes ranged between 3.8 × 105–1.9 × 106 copies g−1 of soil. Temperature was positively correlated with CH4 uptake rates (P<0.001), but had no effect on methanotrophic population dynamics. The soil moisture was negatively correlated with CH4 uptake rates (P<0.001), but showed a positive correlation with changes in USCα-like diversity (P<0.001) and pmoA gene abundance (P<0.05). These were greatest at low net CH4 uptake rates during winter times and coincided with an overall increase in bacterial 16S rRNA gene abundances (P<0.05). Taken together, soil moisture had a significant but opposed effect on CH4 uptake rates and methanotrophic population dynamics, the latter being increasingly stimulated by soil moisture contents >50 vol% and primarily related to members of the MHP clade. PMID:22189499

Linking activity, composition and seasonal dynamics of atmospheric methane oxidizers in a meadow soil.

PubMed

Shrestha, Pravin Malla; Kammann, Claudia; Lenhart, Katharina; Dam, Bomba; Liesack, Werner

2012-06-01

Microbial oxidation is the only biological sink for atmospheric methane. We assessed seasonal changes in atmospheric methane oxidation and the underlying methanotrophic communities in grassland near Giessen (Germany), along a soil moisture gradient. Soil samples were taken from the surface layer (0-10 cm) of three sites in August 2007, November 2007, February 2008 and May 2008. The sites showed seasonal differences in hydrological parameters. Net uptake rates varied seasonally between 0 and 70 μg CH(4) m(-2) h(-1). Greatest uptake rates coincided with lowest soil moisture in spring and summer. Over all sites and seasons, the methanotrophic communities were dominated by uncultivated methanotrophs. These formed a monophyletic cluster defined by the RA14, MHP and JR1 clades, referred to as upland soil cluster alphaproteobacteria (USCα)-like group. The copy numbers of pmoA genes ranged between 3.8 × 10(5)-1.9 × 10(6) copies g(-1) of soil. Temperature was positively correlated with CH(4) uptake rates (P<0.001), but had no effect on methanotrophic population dynamics. The soil moisture was negatively correlated with CH(4) uptake rates (P<0.001), but showed a positive correlation with changes in USCα-like diversity (P<0.001) and pmoA gene abundance (P<0.05). These were greatest at low net CH(4) uptake rates during winter times and coincided with an overall increase in bacterial 16S rRNA gene abundances (P<0.05). Taken together, soil moisture had a significant but opposed effect on CH(4) uptake rates and methanotrophic population dynamics, the latter being increasingly stimulated by soil moisture contents >50 vol% and primarily related to members of the MHP clade.

The African American Women and Mass Media (AAMM) campaign in Georgia: quantifying community response to a CDC pilot campaign

PubMed Central

Johnson-Turbes, Ashani; Berkowitz, Zahava; Zavahir, Yasmine

2015-01-01

Purpose To evaluate whether a culturally appropriate campaign using “Black radio” and print media increased awareness and utilization of local mammography screening services provided by the Centers for Disease Control and Prevention’s National Breast and Cervical Cancer Early Detection Program among African American women. Methods The evaluation used a quasi-experimental design involving data collection during and after campaign implementation in two intervention sites in GA (Savannah with radio and print media and Macon with radio only) and one comparison site (Columbus, GA). We used descriptive statistics to compare mammography uptake for African American women during the initial months of the campaign (8/08–1/09) with the latter months (2/09–8/09) and a post-campaign (9/09–12/09) period in each of the study sites. Comparisons of monthly mammogram uptake between cities were performed with multinomial logistic regression. We assumed a p value <0.05 to be significant. Results We observed an increase of 46 and 20 % in Savannah and Macon, respectively, from the initial period of the campaign to the later period. However, the increase did not persist in the post-campaign period. Analysis comparing monthly mammogram uptake in Savannah and Macon with Columbus showed a significant increase in uptake from the first to the second period in Savannah only (OR 1.269, 95 % CI (1.005–1.602), p = 0.0449). Conclusions Dissemination of health promotion messages via a culturally appropriate, multicomponent campaign using Black radio and print media was effective in increasing mammogram uptake in Savannah among low-income, African American women. Additional research is needed to quantify the relative contribution of campaign radio, print media, and community components to sustain increased mammography uptake. PMID:25732344

Study of the radiocesium dynamics in the Fukushima forest ecosystems

NASA Astrophysics Data System (ADS)

Yoschenko, Vasyl; Konoplev, Alexei; Takase, Tsugiko; Nanba, Kenji; Onda, Yuichi; Zheleznyak, Mark; Kivva, Sergii

2016-04-01

Accident at Fukushima Dai-ichi NPP on March 11, 2011, has resulted in release into the environment of large amounts of radiocesium (134Cs and 137Cs) and in radioactive contamination of terrestrial and aquatic ecosystems. Up to 2/3 of the most contaminated territory in Fukushima prefecture is covered with forests, and efforts aimed at revitalization of this territory should include, therefore, elaboration of the forestry strategy. In particular, understanding of the radiocesium dynamics in the ecosystem compartments is necessary for the reliable long-term prognosis. Numerous studies revealed and quantified the key processes governing radiocesium redistribution in Fukushima forests at the early stage after the accident, when initially intercepted radiocesium was gradually transported from the trees' crowns to the soil surface and profile with precipitations and litterfall, and the general trend was a decrease of the radiocesium total inventory in the forest biomass. However, at the later stage, the radiocesium activities in the biomass compartments can increase due to its root uptake from the soil profile; the two major processes, radionuclide root uptake and its return to soil, will determine the future radiocesium levels in the forest compartments. Objectives of our study were characterization of the radiocesium distribution at the beginning of the late stage, revealing its dynamics and parameterization of the above-mentioned fluxes for prognosis of the radiocesium long-term redistribution in the typical Fukushima forest ecosystems. The study started at one experimental site (Yamakiya district, Kawamata town, Fukushima Prefecture) in the spring of 2014; to the moment, it has been continuing at several experimental sites in the Fukushima zone characterized by different species composition and soil-landscape conditions. For the typical Japanese cedar (Cryptomeria japonica) and Japanese red pine (Pinus Densiflora) forests, we determined distributions of radiocesium in the ecosystems and in the aboveground biomass compartments by the end of 2014 or 2015. At the best studied Yamakiya site the radiocesium distributions were determined for the two consequent years. In 2014, about 74% of the total radiocesium inventory at this site was localized in soil, 20% was in the litter, and only 6% was associated with the aboveground biomass. Within the tree compartments, the largest radiocesium activity fraction, about 46%, was observed in old foliage. The aggregate soil-to-wood transfer factor was 0.0011 m2/kg d.w. Based on the radiocesium activities measured in the biomass compartments of the studied ecosystems, we derived the estimates of its main fluxes and compared to the apparent dynamics of its inventories in biomass at the Yamakiya site.

Biogeochemistry and plant physiological traits interact to reinforce patterns of post-fire dominance in boreal forests

NASA Astrophysics Data System (ADS)

Shenoy, A.; Kielland, K.; Johnstone, J. F.

2011-12-01

Increases in the frequency, extent, and severity of fire in the North American boreal region are projected to continue under a warming climate and are likely to be associated with changes in future vegetation composition. In interior Alaska, fire severity is linked to the relative dominance of deciduous versus coniferous canopy species. Severely burned areas have high levels of deciduous recruitment and subsequent stand dominance, while lightly burned areas exhibit black spruce self-replacement. To elucidate potential mechanisms by which differential fire severity results in differential post-fire vegetation development, we examined changes in soil nitrogen (N) supply (NO3- and NH4+) and in situ 15N uptake by young aspen (Populus tremuloides) and black spruce (Picea mariana) trees growing in lightly and severely burned areas. We hypothesized that (a) soil nitrate supply would be higher in severely burned sites and (b) since conifers have been shown to have a reduced physiological capacity for NO3- uptake, aspen would display greater rates of NO3- uptake than spruce in severely burned sites. Our results suggested that the composition and magnitude of inorganic N supply 14 years after the fire was nearly identical in high-severity and low-severity sites, and nitrate represented nearly 50% of the supply. However, both aspen and spruce took up substantially more NH4+-N than NO3- -N regardless of fire severity. Surprisingly, spruce exhibited only a moderately lower rate of NO3- uptake (μg N/g root-1h-1) than aspen. At the stand level, aspen took up nearly an order-of-magnitude more N per hectare in severely burned sites compared to lightly burned sites, while spruce exhibited the opposite pattern of N uptake with respect to fire severity. Whereas ammonium appeared to be preferred by both species, nitrate represented a larger component of N uptake (based on the NO3-:NH4+ uptake ratio) in aspen (0.7) than in spruce (0.4). We suggest that these species-specific differences in N preference coupled with their respective physiological response to fire severity represent a positive feedback loop that reinforce the opposing stand dominance patterns that have developed at the two ends of the fire severity spectrum. Shifts in forest composition from the current dominance by conifers to a future landscape dominated by deciduous forest are of concern due to impacts on climate-albedo feedbacks, forest productivity, ecosystem carbon storage, and wildlife habitat use.

Temperature responses of carbon monoxide and hydrogen uptake by vegetated and unvegetated volcanic cinders

PubMed Central

King, Caitlin E; King, Gary M

2012-01-01

Ecosystem succession on a large deposit of volcanic cinders emplaced on Kilauea Volcano in 1959 has resulted in a mosaic of closed-canopy forested patches and contiguous unvegetated patches. Unvegetated and unshaded surface cinders (Bare) experience substantial diurnal temperature oscillations ranging from moderate (16 °C) to extreme (55 °C) conditions. The surface material of adjacent vegetated patches (Canopy) experiences much smaller fluctuations (14–25 °C) due to shading. To determine whether surface material from these sites showed adaptations by carbon monoxide (CO) and hydrogen (H2) consumption to changes in ambient temperature regimes accompanying succession, we measured responses of CO and H2 uptake to short-term variations in temperature and long-term incubations at elevated temperature. Based on its broader temperature optimum and lower activation energy, Canopy H2 uptake was less sensitive than Bare H2 uptake to temperature changes. In contrast, Bare and Canopy CO uptake responded similarly to temperature during short-term incubations, indicating no differences in temperature sensitivity. However, during extended incubations at 55 °C, CO uptake increased for Canopy but not Bare material, which indicated that the former was capable of thermal adaptation. H2 uptake for material from both sites was completely inhibited at 55 °C throughout extended incubations. These results indicated that plant development during succession did not elicit differences in short-term temperature responses for Bare and Canopy CO uptake, in spite of previously reported differences in CO oxidizer community composition, and differences in average daily and extreme temperatures. Differences associated with vegetation due to succession did, however, lead to a notable capacity for thermophilic CO uptake by Canopy but not Bare material. PMID:22258097

Temperature responses of carbon monoxide and hydrogen uptake by vegetated and unvegetated volcanic cinders.

PubMed

King, Caitlin E; King, Gary M

2012-08-01

Ecosystem succession on a large deposit of volcanic cinders emplaced on Kilauea Volcano in 1959 has resulted in a mosaic of closed-canopy forested patches and contiguous unvegetated patches. Unvegetated and unshaded surface cinders (Bare) experience substantial diurnal temperature oscillations ranging from moderate (16 °C) to extreme (55 °C) conditions. The surface material of adjacent vegetated patches (Canopy) experiences much smaller fluctuations (14-25 °C) due to shading. To determine whether surface material from these sites showed adaptations by carbon monoxide (CO) and hydrogen (H(2)) consumption to changes in ambient temperature regimes accompanying succession, we measured responses of CO and H(2) uptake to short-term variations in temperature and long-term incubations at elevated temperature. Based on its broader temperature optimum and lower activation energy, Canopy H(2) uptake was less sensitive than Bare H(2) uptake to temperature changes. In contrast, Bare and Canopy CO uptake responded similarly to temperature during short-term incubations, indicating no differences in temperature sensitivity. However, during extended incubations at 55 °C, CO uptake increased for Canopy but not Bare material, which indicated that the former was capable of thermal adaptation. H(2) uptake for material from both sites was completely inhibited at 55 °C throughout extended incubations. These results indicated that plant development during succession did not elicit differences in short-term temperature responses for Bare and Canopy CO uptake, in spite of previously reported differences in CO oxidizer community composition, and differences in average daily and extreme temperatures. Differences associated with vegetation due to succession did, however, lead to a notable capacity for thermophilic CO uptake by Canopy but not Bare material.

Adsorption of phosphate from seawater on calcined MgMn-layered double hydroxides.

PubMed

Chitrakar, Ramesh; Tezuka, Satoko; Sonoda, Akinari; Sakane, Kohji; Ooi, Kenta; Hirotsu, Takahiro

2005-10-01

Adsorptive properties of MgMn-3-300 (MgMn-type layered double hydroxide with Mg/Mn mole ratio of 3, calcined at 300 degrees C) for phosphate were investigated in phosphate-enriched seawater with a concentration of 0.30 mg-P/dm3. It showed the highest phosphate uptake from the seawater among the inorganic adsorbents studied (hydrotalcite, calcined hydrotalcite, activated magnesia, hydrous aluminum oxide, manganese oxide (delta-MnO2)). The phosphate uptake by MgMn-3-300 reached 7.3 mg-P/g at an adsorbent/solution ratio of 0.05 g/2 dm3. The analyses of the uptakes of other constituents (Na+, K+, Ca(+, Cl-, and SO(2-)4) of seawater showed that the adsorbent had a markedly high selectivity for the adsorption of phosphate ions. Effects of initial phosphate concentration, temperature, pH, and salinity on phosphate uptake were investigated in detail by a batch method. The phosphate uptake increased slightly with an increase in the adsorption temperature. The adsorption isotherm followed Freundlich's equation with constants of logK(F)=1.25 and 1/n=0.65, indicating that it could effectively remove phosphate even from a solution of markedly low phosphate concentration as well as with large numbers of coexisting ions. The pH dependence showed a maximum phosphate uptake around pH 8.5. The pH dependence curve suggested that selective phosphate adsorption progresses mainly by the ion exchange of HPO(2-)4. The study on the effect of salinity suggested the presence of two kinds of adsorption sites in the adsorbent: one nonspecific site with weak interaction and one specific site with strong interaction. The effective desorption of phosphate could be achieved using a mixed solution of 5 M NaCl + 0.1 M NaOH (1 M = 1 mol/dm3), with negligible dissolution of adsorbent. The adsorbent had high chemical stability against the adsorption/desorption cycle; it kept a good phosphate uptake even after the repetition of the seventh cycle.

Assessment of producers' response to Salmonella biosecurity issues and uptake of advice on laying hen farms in England and Wales.

PubMed

Gosling, R J; Martelli, F; Wintrip, A; Sayers, A R; Wheeler, K; Davies, R H

2014-01-01

High standards of biosecurity are known to reduce the risk of disease outbreaks; however, uptake of advice and implementation of biosecurity measures are dependent on many factors. This study assessed the uptake of targeted biosecurity advice by 60 laying hen farms provided during biosecurity audit visits. Advice was provided as bullet point cards focusing on specific areas identified as benefitting from improvement. These covered site entrance, site tidiness, vaccination, boot hygiene, hand hygiene, house tidiness, rodent control, fly control, red mite control and cleaning and disinfection between flocks. Background knowledge of Salmonella and biosecurity and farmers' willingness and intent to implement additional measures were assessed. About 50% of the principal decision-makers had basic background knowledge of Salmonella, with 22% considered well informed; almost all agreed that biosecurity could impact on Salmonella control and many appeared willing to implement additional biosecurity measures. Sixty-three per cent of study farms were categorised using the Defra Farmer Segmentation Model as Modern Family Businesses (MFBs), with 7-11% of farms being categorised as Custodian, Lifestyle Choice, Pragmatist or Challenged Enterprise; however, categorisation, did not determine uptake of advice. The most frequently used advice cards were boot hygiene, red mite control, hand hygiene, site entrance and cleaning and disinfection; uptake of advice ranged from 54 to 80% depending on the advice card. Uptake of advice by the farmers was encouraging, especially considering it was being provided by people other than their usual source of biosecurity information. Those who did not implement the recommended measures cited cost, difficulty of enforcement and practicality as the main reasons. However, the positive uptake of advice and implementation of recommended measures by many farmers demonstrates that targeted advice, discussed face to face with farmers, on a small number of key areas, is a potentially effective method of providing biosecurity information to complement more lengthy formal advisory reports.

Interaction of SR 33557 with skeletal muscle calcium channel blocker receptors in the baboon: characterization of its binding sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sol-Rolland, J.; Joseph, M.; Rinaldi-Carmona, M.

1991-05-01

A procedure for the isolation of primate skeletal microsomal membranes was initiated. Membranes exhibited specific enzymatic markers such as 5'-nucleotidase, Ca{sup 2}{sup +},Mg({sup 2}{sup +})-adenosine triphosphatase and an ATP-dependent calcium uptake. Baboon skeletal microsomes bound specifically with high-affinity potent Ca{sup 2}{sup +} channel blockers such as dihydropyridine, phenylalkylamine and benzothiazepine derivatives. Scatchard analysis of equilibrium binding assays with ({sup 3}H)(+)-PN 200-110, ({sup 3}H)(-)-desmethoxyverapamil (( {sup 3}H)(-)-D888) and ({sup 3}H)-d-cis-dilitiazem were consistent with a single class of binding sites for the three radioligands. The pharmacological profile of SR 33557, an original compound with calcium antagonist properties, was investigated using radioligand bindingmore » studies. SR 33557 totally inhibited the specific binding of the three main classes of Ca{sup 2}{sup +} channel effectors and interacted allosterically with them. In addition, SR 33557 bound with high affinity to a homogeneous population of binding sites in baboon skeletal muscle.« less

Fat-soluble vitamin intestinal absorption: absorption sites in the intestine and interactions for absorption.

PubMed

Goncalves, Aurélie; Roi, Stéphanie; Nowicki, Marion; Dhaussy, Amélie; Huertas, Alain; Amiot, Marie-Josèphe; Reboul, Emmanuelle

2015-04-01

The interactions occurring at the intestinal level between the fat-soluble vitamins A, D, E and K (FSVs) are poorly documented. We first determined each FSV absorption profile along the duodenal-colonic axis of mouse intestine to clarify their respective absorption sites. We then investigated the interactions between FSVs during their uptake by Caco-2 cells. Our data show that vitamin A was mostly absorbed in the mouse proximal intestine, while vitamin D was absorbed in the median intestine, and vitamin E and K in the distal intestine. Significant competitive interactions for uptake were then elucidated among vitamin D, E and K, supporting the hypothesis of common absorption pathways. Vitamin A also significantly decreased the uptake of the other FSVs but, conversely, its uptake was not impaired by vitamins D and K and even promoted by vitamin E. These results should be taken into account, especially for supplement formulation, to optimise FSV absorption. Copyright © 2014 Elsevier Ltd. All rights reserved.

AmeriFlux US-UMd UMBS Disturbance

DOE Data Explorer

Curtis, Peter [Ohio State University; Gough, Christopher [Virginia Commonwealth University

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-UMd UMBS Disturbance. Site Description - The UMBS Disturbance site is an artificial disturbance site that has recently been created as part of the Forest Accelerate Succession ExperimenT (FASET). In Spring 2008, every aspen and birch tree (>6,700, ~35% canopy LAI), the dominant early successional trees, were girdled over 39 ha of the FASET treatment plot to stimulate a disturbance that will move the forest into a later successional stage, dominated by maples, oaks, and white pine. This treatment caused aspen and birch mortality within 2 - 3 years. As a result of the changed canopy structure, there is a divergence in net ecosystem exchange between the control plot (enhanced carbon uptake) and the treatment plot (reduced carbon uptake).

Timing of electron and proton transfer in the ba(3) cytochrome c oxidase from Thermus thermophilus.

PubMed

von Ballmoos, Christoph; Lachmann, Peter; Gennis, Robert B; Ädelroth, Pia; Brzezinski, Peter

2012-06-05

Heme-copper oxidases are membrane-bound proteins that catalyze the reduction of O(2) to H(2)O, a highly exergonic reaction. Part of the free energy of this reaction is used for pumping of protons across the membrane. The ba(3) oxidase from Thermus thermophilus presumably uses a single proton pathway for the transfer of substrate protons used during O(2) reduction as well as for the transfer of the protons that are pumped across the membrane. The pumping stoichiometry (0.5 H(+)/electron) is lower than that of most other (mitochondrial-like) oxidases characterized to date (1 H(+)/electron). We studied the pH dependence and deuterium isotope effect of the kinetics of electron and proton transfer reactions in the ba(3) oxidase. The results from these studies suggest that the movement of protons to the catalytic site and movement to a site located some distance from the catalytic site [proposed to be a "proton-loading site" (PLS) for pumped protons] are separated in time, which allows individual investigation of these reactions. A scenario in which the uptake and release of a pumped proton occurs upon every second transfer of an electron to the catalytic site would explain the decreased proton pumping stoichiometry compared to that of mitochondrial-like oxidases.

Characterisation of glufosinate resistance mechanisms in Eleusine indica.

PubMed

Jalaludin, Adam; Yu, Qin; Zoellner, Peter; Beffa, Roland; Powles, Stephen B

2017-06-01

An Eleusine indica population has evolved resistance to glufosinate, a major post-emergence herbicide of global agriculture. This population was analysed for target-site (glutamine synthetase) and non-target-site (glufosinate uptake, translocation and metabolism) resistance mechanisms. Glutamine synthetase (GS) activity extracted from susceptible (S) and resistant (R*) plants was equally sensitive to glufosinate inhibition, with IC 50 values of 0.85 mm and 0.99 mm, respectively. The extractable GS activity was also similar in S and R* samples. Foliar uptake of [ 14 C]-glufosinate did not differ in S and R* plants, nor did glufosinate net uptake in leaf discs. Translocation of [ 14 C]-glufosinate into untreated shoots and roots was also similar in both populations, with 44% to 47% of the herbicide translocated out from the treated leaf 24 h after treatment. The HPLC and LC-MS analysis of glufosinate metabolism revealed no major metabolites in S or R* leaf tissue. Glufosinate resistance in this resistant population is not due to an insensitive GS, or increased activity, or altered glufosinate uptake and translocation, or enhanced glufosinate metabolism. Thus, target-site resistance is likely excluded and the exact resistance mechanism(s) remain to be determined. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

A Phase 2 Study of 16α-[18F]-fluoro-17β-estradiol Positron Emission Tomography (FES-PET) as a Marker of Hormone Sensitivity in Metastatic Breast Cancer (MBC)

PubMed Central

Peterson, Lanell M.; Kurland, Brenda F.; Schubert, Erin K.; Link, Jeanne M.; Gadi, V.K.; Specht, Jennifer M.; Eary, Janet F.; Porter, Peggy; Shankar, Lalitha K.; Mankoff, David A.; Linden, Hannah M.

2014-01-01

Purpose 16α-[18F]-fluoro-17β-estradiol positron emission tomography (FES-PET) quantifies estrogen receptor (ER) expression in tumors and may provide diagnostic benefit. Procedures Women with newly diagnosed metastatic breast cancer (MBC) from an ER-positive primary tumor were imaged before starting endocrine therapy. FES uptake was evaluated qualitatively and quantitatively, and associated with response and with ER expression. Results Nineteen patients underwent FES imaging. Fifteen had a biopsy of a metastasis and 15 were evaluable for response. Five patients had quantitatively low FES uptake, six had at least one site of qualitatively FES-negative disease. All patients with an ER-negative biopsy had both low uptake and at least one site of FES-negative disease. Of response-evaluable patients, 2/2 with low FES standard uptake value tumors had progressive disease within 6 months, as did 2/3 with qualitatively FES-negative tumors. Conclusions Low/absent FES uptake correlates with lack of ER expression. FES-positron emission tomography can help identify patients with endocrine resistant disease and safely measures ER in MBC. PMID:24170452

ComEA Is Essential for the Transfer of External DNA into the Periplasm in Naturally Transformable Vibrio cholerae Cells

PubMed Central

Seitz, Patrick; Pezeshgi Modarres, Hassan; Borgeaud, Sandrine; Bulushev, Roman D.; Steinbock, Lorenz J.; Radenovic, Aleksandra; Dal Peraro, Matteo; Blokesch, Melanie

2014-01-01

The DNA uptake of naturally competent bacteria has been attributed to the action of DNA uptake machineries resembling type IV pilus complexes. However, the protein(s) for pulling the DNA across the outer membrane of Gram-negative bacteria remain speculative. Here we show that the competence protein ComEA binds incoming DNA in the periplasm of naturally competent Vibrio cholerae cells thereby promoting DNA uptake, possibly through ratcheting and entropic forces associated with ComEA binding. Using comparative modeling and molecular simulations, we projected the 3D structure and DNA-binding site of ComEA. These in silico predictions, combined with in vivo and in vitro validations of wild-type and site-directed modified variants of ComEA, suggested that ComEA is not solely a DNA receptor protein but plays a direct role in the DNA uptake process. Furthermore, we uncovered that ComEA homologs of other bacteria (both Gram-positive and Gram-negative) efficiently compensated for the absence of ComEA in V. cholerae, suggesting that the contribution of ComEA in the DNA uptake process might be conserved among naturally competent bacteria. PMID:24391524

Characterization of cadmium uptake and cytotoxicity in human osteoblast-like MG-63 cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levesque, Martine; Martineau, Corine; Jumarie, Catherine

Since bone mass is maintained constant by the balance between osteoclastic bone resorption and osteoblastic bone formation, alterations in osteoblast proliferation and differentiation may disturb the equilibrium of bone remodeling. Exposure to cadmium (Cd) has been associated with the alteration of bone metabolism and the development of osteoporosis. Because little information is available about the direct effects of Cd on osteoblastic cells, we have characterized in vitro the cellular accumulation and cytotoxicity of Cd in human osteoblastic cells. Incubation of osteoblast-like MG-63 cells with increasing concentrations of Cd in serum-free culture medium reduced cell viability in a time- and concentration-dependentmore » manner, suggesting that Cd accumulates in osteoblasts. Consequently, an uptake time-course could be characterized for the cellular accumulation of {sup 109}Cd in serum-free culture medium. In order to characterize the mechanisms of Cd uptake, experiments have been conducted under well-defined metal speciation conditions in chloride and nitrate transport media. The results revealed a preferential uptake of Cd{sup 2+} species. The cellular accumulation and cytotoxicity of Cd increased in the absence of extracellular calcium (Ca), suggesting that Cd may enter the cells in part through Ca channels. However, neither the cellular accumulation nor the cytotoxicity of Cd was modified by voltage-dependent Ca channel (VDCC) modulators or potassium-induced depolarization. Moreover, exposure conditions activating or inhibiting capacitative Ca entry (CCE) failed to modify the cellular accumulation and cytotoxicity of Cd, which excludes the involvement of canonical transient receptor potential (TRPC) channels. The cellular accumulation and cytotoxicity of Cd were reduced by 2-APB, a known inhibitor of the Mg and Ca channel TRPM7 and were increased in the absence of extracellular magnesium (Mg). The inhibition of Cd uptake by Mg and Ca was not additive, suggesting that each ion inhibits the same uptake mechanism. Our results indicate that Cd uptake in human osteoblastic cells occurs, at least in part, through Ca- and Mg-inhibitable transport mechanisms, which may involve channels of the TRPM family. The effect of Cd on bone metabolism may be enhanced under low Ca and/or Mg levels.« less

Pharmacological evaluation of an [(123)I] labelled imidazopyridine-3-acetamide for the study of benzodiazepine receptors.

PubMed

Mattner, Filomena; Mardon, Karine; Loc'h, Christian; Katsifis, Andrew

2006-06-13

In vitro binding of the iodinated imidazopyridine, N',N'-dimethyl-6-methyl-(4'-[(123)I]iodophenyl)imidazo[1,2-a]pyridine-3-acetamide [(123)I]IZOL to benzodiazepine binding sites on brain cortex, adrenal and kidney membranes is reported. Saturation experiments showed that [(123)I]IZOL, bound to a single class of binding site (n(H)=0.99) on adrenal and kidney mitochondrial membranes with a moderate affinity (K(d)=30 nM). The density of binding sites was 22+/-6 and 1.2+/-0.4 pmol/mg protein on adrenal and kidney membranes, respectively. No specific binding was observed in mitochondrial-synaptosomal membranes of brain cortex. In biodistribution studies in rats, the highest uptake of [(123)I]IZOL was found 30 min post injection in adrenals (7.5% ID/g), followed by heart, kidney, lung (1% ID/g) and brain (0.12% ID/g), consistent with the distribution of peripheral benzodiazepine binding sites. Pre-administration of unlabelled IZOL and the specific PBBS drugs, PK 11195 and Ro 5-4864 significantly reduced the uptake of [(123)I]IZOL by 30% (p<0.05) in olfactory bulbs and by 51-86% (p<0.01) in kidney, lungs, heart and adrenals, while it increased by 30% to 50% (p<0.01) in the rest of the brain and the blood. Diazepam, a mixed CBR-PBBS drug, inhibited the uptake in kidney, lungs, heart, adrenals and olfactory bulbs by 32% to 44% (p<0.01) but with no effect on brain uptake and in blood concentration. Flumazenil, a central benzodiazepine drug and haloperidol (dopamine antagonist/sigma receptor drug) displayed no effect in [(123)I]IZOL in peripheral organs and in the brain. [(123)I]IZOL may deserve further development for imaging selectively peripheral benzodiazepine binding sites.

In vitro uptake of apoptotic body mimicking phosphatidylserine-quantum dot micelles by monocytic cell line

NASA Astrophysics Data System (ADS)

Maiseyeu, Andrei; Bagalkot, Vaishali

2014-04-01

A new quantum dot (QD) PEGylated micelle laced with phosphatidylserine (PS) for specific scavenger receptor-mediated uptake by macrophages is reported. The size and surface chemistry of PS-QD micelles were characterized by standard methods and the effects of their physicochemical properties on specific targeting and uptake were comprehensively studied in a monocytic cell line (J774A.1).

Testicular regulation of neuronal glucose and monocarboxylate transporter gene expression profiles in CNS metabolic sensing sites during acute and recurrent insulin-induced hypoglycemia.

PubMed

Vavaiya, Kamlesh V; Paranjape, Sachin A; Briski, Karen P

2007-01-01

Recurrent insulin-induced hypoglycemia (RIIH) impairs glucose counter-regulatory function in male humans and rodents and, in the latter, diminishes neuronal activation in CNS structures that monitor metabolic homeostasis, including the lateral hypothalamic area (LHA) and dorsal vagal complex (DVC). We investigated whether habituated neuronal reactivity in CNS sensing sites to hypoglycemia is correlated with modified monocarboxylate and/or glucose uptake by using quantitative real-time RT-PCR to analyze neuronal monocarboxylate transporter (MCT2) and glucose transporter variant (GLUT and GLUT4) gene expression profiles in the microdissected LHA, ventromedial nucleus hypothalamus (VMH), and DVC after one or multiple insulin injections. Because orchidectomy (ORDX) maintains uniform glycemic responses to RIIH in male rats, we also examined whether regional gene response patterns are testes dependent. In the intact male rat DVC, MCT2, GLUT3, and GLUT4 gene expression was not altered by acute hypoglycemia but was enhanced by RIIH. MCT2 and GLUT3 mRNA levels in the ORDX rat DVC did not differ among groups, but GLUT4 transcripts were progressively increased by acute and recurrent hypoglycemia. Precedent hypoglycemia decreased or increased basal MCT2 and GLUT4 gene expression, respectively, in the intact rat LHA; LHA GLUT3 transcription was augmented by RIIH in intact rats only. Acute hypoglycemia suppressed MCT2, GLUT3, and GLUT4 gene expression in the intact rat VMH, a response that was abolished by RIIH. In ORDX rats, VMH gene transcript levels were unchanged in response to one dose of insulin but were selectively diminished during RIIH. These data demonstrate site-specific, testes-dependent effects of acute and recurrent hypoglycemia on neuronal metabolic substrate transporter gene expression in characterized rat brain metabolic sensing loci and emphasize the need to assess the impact of potential alterations in glucose and lactate uptake during RIIH on general and specialized, e.g., metabolic monitoring, functions of neurons in those sites.

A black alder plantation improves the greenhouse gas balance of a degraded moist peat grassland

NASA Astrophysics Data System (ADS)

Bereswill, Sarah; Hoffmann, Mathias; Huth, Vytas; Popova, Yulia; Zak, Dominik; Augustin, Jürgen

2017-04-01

Drained peatlands are among the strongest terrestrial sources of the greenhouse gases (GHG) CO2 and N2O. Therefore, activities of peatland revitalisation through rewetting, often combined with the implementation of peat forming vegetation, aim to restore the GHG sink function that is characteristic for pristine peatlands. Black alder (Alnus glutinosa) naturally occurs in temperate marshes and minerotrophic peatlands (= fens) and is also suitable for paludiculture, the cultivation of biomass on wet or rewetted peatlands. However, only little information exists, if a black alder plantation can reduce the climate impact of restored peatlands. Therefore, we investigated the effect of a newly established black alder plantation on the net GHG balance of a degraded fen in north-eastern Germany during a two-year study (August 2010 - August 2012). We compared the alder plantation (Awet) with an extensively used meadow (Mwet) both characterized by very moist soil conditions and a drier reference meadow (Mdry) characterized by moderately moist soil conditions. CO2, CH4 and N2O fluxes were measured monthly to bi-monthly with the manual closed chamber method. Fluxes were calculated using a modular R script and gap filled to obtain continuous daily fluxes. Awet was a net GHG sink of -4.8 t CO2-eq ha-1 yr-1, Mwet was climate neutral (-0.03 t CO2-eq ha-1 yr-1), and Mdry was a net GHG source of 15.7 t CO2-eq ha-1 yr-1. This was mainly caused by CO2 uptake at the two very moist sites and a high CO2 release at the drier reference site. In addition, Awet was a larger CO2 sink than Mwet, likely caused by an additional CO2 uptake of the alder stand. All sites were significant CH4 sources. Due to inundation following extraordinarily heavy precipitation in summer 2011 remarkable CH4emission peaks were found on all sites which accounted for up to 70 % of the cumulated two-year CH4emissions. However, overall Awet emitted significantly lesser CH4(4.9 g C m-2 yr-1). We assume that the black alders decreased the CH4emissions due to their effective O2 transport mechanism. N2O emissions were negligible at all three sites. Our results indicate that rewetting and planting black alders significantly improve the GHG balances of formerly drained fens already in the first two years after plantation. Furthermore, only one wet summer significantly increased the CH4 emissions of our study site, despite two-year average groundwater levels (GWL) of -0.2 to -0.35 m. This highlights the importance of acknowledging extreme precipitation events and groundwater fluctuations for the derivation of reliable GHG emission factors.

Using Digital Repeat Photography to Link Vegetative Phenology and Carbon Fluxes to Biotic and Abiotic Drivers in Three Semi-arid Systems (New Mexico, USA)

NASA Astrophysics Data System (ADS)

Hallmark, A.; Litvak, M. E.; Collins, S. L.

2015-12-01

Arid and semi-arid ecosystems account for over 45% of global land cover. While mean annual carbon uptake in these ecosystems is relatively low, aridlands collectively store a significant amount of carbon. There is high inter- and intra-annual variability of plant growth in aridlands, depending largely on the timing and size of rainfall events. This variation is also of great significance, as the variation in annual semi-aridland carbon uptake accounts for ~39% of the inter-annual variability of the global terrestrial carbon sink, the largest percentage of any land cover type. Although arid and semi-arid ecosystems are of global importance, they are understudied. To better understand the drivers and variability of carbon uptake in these critical ecosystems, we utilize a six-year record of digital images (45,000+ images), carbon flux and meteorological data, soil water content, and associated ecological measurements from three eddy covariance tower sites in central New Mexico. These sites include a Chihuahuan Desert/short-grass Plains grassland site, and post-fire successional grassland site, and a creosote-encroached shrubland site, each of which have unique species compositions, carbon fluxes, and reactions to disturbance and resource addition. All images used are co-registered and corrected for radial lens distortions (when necessary) and greenness indices (2GRBi, gcc, and/or NDVI) are calculated for each scene's overall "canopy" and for individual species and plant functional types therein. At all three sites, camera-derived greenness is correlated to measured carbon uptake with fine resolution (R2 up to 0.8), capturing temporal and spatial variation usually not seen in satellite-based imagery. At sites with lower LAI, species-specific ROI's were more correlated to the site's measured carbon flux across shorter time scales. Understanding the biota comprising each image and its contribution to changing scene greenness at different times of year can lead to more accurate carbon flux predictions in semi-arid systems, with species-specific biotic constraints (maximum growth rate, lifespan, and seasonality), growth parameters (light availability, VPD, soil water content, and temperature) as well as community-wide abiotic drivers considered.

Recovery of Platinum from Dilute Chloride Media Using Biosorbents

NASA Astrophysics Data System (ADS)

Zeytuncu, B.; Morcali, M. H.; Yucel, O.

Pistachio nut shells and Rice husk, a biomass residue, were investigated as adsorbents for the platinum uptake from synthetically prepared dilute chloroplatinic acid solutions. The effects of the different uptake parameters on platinum uptake (%) were studied in detail on a batch sorption. Before the pistachio nut shell material was activated, platinum uptake (%) was poor compared with rice husk. However, after the pistachio nut shell material was activated at 1000°C under an argon atmosphere, the platinum uptake (%) increased two-fold. The pistachio nut shell (inactivated and activated) and rice husk were characterized by Attenuated Total Reflection-Fourier transform infrared spectroscopy (ATR-FTIR).

Effects of salinity on short-term waterborne zinc uptake, accumulation and sub-lethal toxicity in the green shore crab (Carcinus maenas).

PubMed

Niyogi, Som; Blewett, Tamzin A; Gallagher, Trevor; Fehsenfeld, Sandra; Wood, Chris M

2016-09-01

Waterborne zinc (Zn) is known to cause toxicity to freshwater animals primarily by disrupting calcium (Ca) homeostasis during acute exposure, but its effects in marine and estuarine animals are not well characterized. The present study investigated the effects of salinity on short-term Zn accumulation and sub-lethal toxicity in the euryhaline green shore crab, Carcinus maenas. The kinetic and pharmacological properties of short-term branchial Zn uptake were also examined. Green crabs (n=10) were exposed to control (no added Zn) and 50μM (3.25mgL(-1)) of waterborne Zn (∼25% of 96h LC50 in 100 seawater) for 96h at 3 different salinity regimes (100%, 60% and 20% seawater). Exposure to waterborne Zn increased tissue-specific Zn accumulation across different salinities. However, the maximum accumulation occurred in 20% seawater and no difference was recorded between 60% and 100% seawater. Gills appeared to be the primary site of Zn accumulation, since the accumulation was significantly higher in the gills relative to the hepatopancreas, haemolymph and muscle. Waterborne Zn exposure induced a slight increase in haemolymph osmolality and chloride levels irrespective of salinity. In contrast, Zn exposure elicited marked increases in both haemolymph and gill Ca levels, and these changes were more pronounced in 20% seawater relative to that in 60% or 100% seawater. An in vitro gill perfusion technique was used to examine the characteristics of short-term (1-4h) branchial Zn uptake over an exposure concentration range of 3-12μM (200-800μgL(-1)). The rate of short-term branchial Zn uptake did not change significantly after 2h, and no difference was recorded in the rate of uptake between the anterior (respiratory) and posterior (ion transporting) gills. The in vitro branchial Zn uptake occurred in a concentration-dependent manner across different salinities. However, the rate of uptake was consistently higher in 20% seawater relative to 60% or 100% seawater - similar to the trend observed with tissue Zn accumulation during in vivo exposure. The short-term branchial Zn uptake was found to be inhibited by lanthanum (a blocker of voltage-independent Ca channels), suggesting that branchial Zn uptake occurs via the Ca transporting pathways, at least in part. Overall, our findings indicate that acute exposure to waterborne Zn leads to the disruption of Zn and Ca homeostasis in green crab, and these effects are exacerbated at the lower salinity. Copyright © 2016 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Napier, Bruce A.; Fellows, Robert J.; Krupka, Kenneth M.

This report describes work performed for the U.S. Nuclear Regulatory Commission’s project Assessment of Food Chain Pathway Parameters in Biosphere Models, which was established to assess and evaluate a number of key parameters used in the food-chain models used in performance assessments of radioactive waste disposal facilities. Section 2 of this report summarizes characteristics of samples of soils and groundwater from three geographical regions of the United States, the Southeast, Northwest, and Southwest, and analyses performed to characterize their physical and chemical properties. Because the uptake and behavior of radionuclides in plant roots, plant leaves, and animal products depends onmore » the chemistry of the water and soil coming in contact with plants and animals, water and soil samples collected from these regions of the United States were used in experiments at Pacific Northwest National Laboratory to determine radionuclide soil-to-plant concentration ratios. Crops and forage used in the experiments were grown in the soils, and long-lived radionuclides introduced into the groundwater provide the contaminated water used to water the grown plants. The radionuclides evaluated include 99Tc, 238Pu, and 241Am. Plant varieties include alfalfa, corn, onion, and potato. The radionuclide uptake results from this research study show how regional variations in water quality and soil chemistry affect radionuclide uptake. Section 3 summarizes the procedures and results of the uptake experiments, and relates the soil-to-plant uptake factors derived. In Section 4, the results found in this study are compared with similar values found in the biosphere modeling literature; the study’s results are generally in line with current literature, but soil- and plant-specific differences are noticeable. This food-chain pathway data may be used by the NRC staff to assess dose to persons in the reference biosphere (e.g., persons who live and work in an area potentially affected by radionuclide releases) of waste disposal facilities and decommissioning sites.« less

Nickel binding to NikA: an additional binding site reconciles spectroscopy, calorimetry and crystallography.

PubMed

Addy, Christine; Ohara, Masato; Kawai, Fumihiro; Kidera, Akinori; Ikeguchi, Mitsunori; Fuchigami, Sotaro; Osawa, Masanori; Shimada, Ichio; Park, Sam-Yong; Tame, Jeremy R H; Heddle, Jonathan G

2007-02-01

Intracellular nickel is required by Escherichia coli as a cofactor for a number of enzymes and is necessary for anaerobic respiration. However, high concentrations of nickel are toxic, so both import and export systems have evolved to control the cellular level of the metal. The nik operon in E. coli encodes a nickel-uptake system that includes the periplasmic nickel-binding protein NikA. The crystal structures of wild-type NikA both bound to nickel and in the apo form have been solved previously. The liganded structure appeared to show an unusual interaction between the nickel and the protein in which no direct bonds are formed. The highly unusual nickel coordination suggested by the crystal structure contrasted strongly with earlier X-ray spectroscopic studies. The known nickel-binding site has been probed by extensive mutagenesis and isothermal titration calorimetry and it has been found that even large numbers of disruptive mutations appear to have little effect on the nickel affinity. The crystal structure of a binding-site mutant with nickel bound has been solved and it is found that nickel is bound to two histidine residues at a position distant from the previously characterized binding site. This novel site immediately resolves the conflict between the crystal structures and other biophysical analyses. The physiological relevance of the two binding sites is discussed.

The role of vegetation in the CO2 flux from a tropical urban neighbourhood

NASA Astrophysics Data System (ADS)

Velasco, E.; Roth, M.; Tan, S. H.; Quak, M.; Nabarro, S. D. A.; Norford, L.

2013-03-01

Urban surfaces are usually net sources of CO2. Vegetation can potentially have an important role in reducing the CO2 emitted by anthropogenic activities in cities, particularly when vegetation is extensive and/or evergreen. Negative daytime CO2 fluxes, for example have been observed during the growing season at suburban sites characterized by abundant vegetation and low population density. A direct and accurate estimation of carbon uptake by urban vegetation is difficult due to the particular characteristics of the urban ecosystem and high variability in tree distribution and species. Here, we investigate the role of urban vegetation in the CO2 flux from a residential neighbourhood in Singapore using two different approaches. CO2 fluxes measured directly by eddy covariance are compared with emissions estimated from emissions factors and activity data. The latter includes contributions from vehicular traffic, household combustion, soil respiration and human breathing. The difference between estimated emissions and measured fluxes should approximate the biogenic flux. In addition, a tree survey was conducted to estimate the annual CO2 sequestration using allometric equations and an alternative model of the metabolic theory of ecology for tropical forests. Palm trees, banana plants and turfgrass were also included in the survey with their annual CO2 uptake obtained from published growth rates. Both approaches agree within 2% and suggest that vegetation captures 8% of the total emitted CO2 in the residential neighbourhood studied. A net uptake of 1.4 ton km-2 day-1 (510 ton km-2 yr-1 ) was estimated from the difference between the daily CO2 uptake by photosynthesis (3.95 ton km-2 ) and release by respiration (2.55 ton km-2). The study shows the importance of urban vegetation at the local scale for climate change mitigation in the tropics.

Protein and Peptide Gas-phase Structure Investigation Using Collision Cross Section Measurements and Hydrogen Deuterium Exchange

NASA Astrophysics Data System (ADS)

Khakinejad, Mahdiar

Protein and peptide gas-phase structure analysis provides the opportunity to study these species outside of their explicit environment where the interaction network with surrounding molecules makes the analysis difficult [1]. Although gas-phase structure analysis offers a unique opportunity to study the intrinsic behavior of these biomolecules [2-4], proteins and peptides exhibit very low vapor pressures [2]. Peptide and protein ions can be rendered in the gas-phase using electrospray ionization (ESI) [5]. There is a growing body of literature that shows proteins and peptides can maintain solution structures during the process of ESI and these structures can persist for a few hundred milliseconds [6-9]. Techniques for monitoring gas-phase protein and peptide ion structures are categorized as physical probes and chemical probes. Collision cross section (CCS) measurement, being a physical probe, is a powerful method to investigate gas-phase structure size [3, 7, 10-15]; however, CCS values alone do not establish a one to one relation with structure(i.e., the CCS value is an orientationally averaged value [15-18]. Here we propose the utility of gas-phase hydrogen deuterium exchange (HDX) as a second criterion of structure elucidation. The proposed approach incudes extensive MD simulations to sample biomolecular ion conformation space with the production of numerous, random in-silico structures. Subsequently a CCS can be calculated for these structures and theoretical CCS values are compared with experimental values to produce a pool of candidate structures. Utilizing a chemical reaction model based on the gas-phase HDX mechanism, the HDX kinetics behavior of these candidate structures are predicted and compared to experimental results to nominate the best in-silico structures which match (chemically and physically) with experimental observations. For the predictive approach to succeed, an extensive technique and method development is essential. To combine CCS measurements and gas-phase HDX studies at the amino acid residue level, for the first time a drift tube is connected to a linear ion trap (LIT) with electron transfer dissociation (ETD) capability[19, 20]. In this manner CCS and per-residue deuterium uptake measurements for a model peptide carried out successfully[19]. In this study, the gas-phase conformations of electrosprayed ions of the model peptide KKDDDDIIKIIK have been examined. Using ion structures obtained from molecular dynamics (MD) simulation and considering charge-site/exchange-site density the level of the maximum total deuterium uptake for the gas-phase ions is explained. Also a new hydrogen accessibility scoring (HAS) model that includes two distance calculations (charge site to carbonyl group and carbonyl group to exchange site) is applied to the in-silico structures to describe the expected HDX behavior for these structures. Further investigation to improve the accuracy of the model is accomplished by a "per-residue" HDX kinetics study of the model peptide [21]. In this study, the ion residence time and the deuterium uptake of each residue is measured at different partial pressures of D2O. Subsequently the contribution each residue to the overall HDX rate of the intact peptide ion is calculated. These rate contributions of the residues exhibit a better fit to HAS than their maximum deuterium uptake. Proteins and peptides with very frequent acidic residue in their sequence provide very poor signal levels when employing positive polarity ESI. Also, the comparison of protonated and deprotonated ions of these biomolecules offers the potential to provide a better structural characterization [22]. Per-residue deuterium uptake values resulting from collision-induced dissociation (CID) of the model peptide KKDDDDIIKIIK were used to investigated the degree of hydrogen deuterium scrambling for deprotonated ions [23]. Remarkably, limited isotopic scrambling was observed in this study of this small model peptide. This data and the per-residue deuterium uptake of the triply-protonated model peptide Acetyl-PAAAAKAAAAKAAAAKAAAAK are exploited to propose a lemma to allocate protonation and deprotonation sites for peptide ions in the gas-phase. Insulin ions, as a small protein model system, are examined to investigate the relation of the maximum deuterium uptake value for each insulin chain to the exposed surface area of each insulin subunit [22]. The results show that the methodology can be applied on the protein complexes to provide information about the exposed surface area of each subunit.

Transcriptomic and physiological characterization of the fefe mutant of melon (Cucumis melo) reveals new aspects of iron–copper crosstalk

PubMed Central

Waters, Brian M.; McInturf, Samuel A.; Amundsen, Keenan

2014-01-01

Summary Iron (Fe) and copper (Cu) homeostasis are tightly linked across biology. In previous work, Fe deficiency interacted with Cu regulated genes and stimulated Cu accumulation. The C940-fe (fefe) Fe uptake mutant of melon (Cucumis melo) was characterized, and the fefe mutant was used to test whether Cu deficiency could stimulate Fe uptake. Wild type and fefe mutant transcriptomes were determined by RNA-seq under Fe and Cu deficiency. FeFe regulated genes included core Fe uptake, metal homeostasis, and transcription factor genes. Numerous genes were regulated by both Fe and Cu. The fefe mutant was rescued by high Fe or by Cu deficiency, which stimulated ferric-chelate reductase activity, FRO2 expression, and Fe accumulation. Accumulation of Fe in Cu deficient plants was independent of the normal Fe uptake system. One of the four FRO genes in the melon and cucumber (Cucumis sativus) genomes was Fe regulated, and one was Cu regulated. Simultaneous Fe and Cu deficiency synergistically upregulated Fe uptake gene expression. Overlap in Fe and Cu deficiency transcriptomes highlights the importance of Fe– Cu crosstalk in metal homeostasis. The fefe gene is not orthologous to FIT, thus identification of this gene will provide clues to help understand regulation of Fe uptake in plants. PMID:24975482

Utilization of a Model for Uptake of Cadmium by Plants as a Phytoremediation Assessment Tool

NASA Astrophysics Data System (ADS)

Takahashi, M.; Furbish, D. J.; Clarke, J.

2008-12-01

Some traditional methods of environmental remediation, such as removal and disposal of contaminated soil, are loosing economic favor and public acceptance, while others, such as in situ phytoremediation, are being carefully examined because of their attractiveness as environmentally friendly, low-cost solutions to site clean-up. The success of phytoremediation strategies, however, hinges on the ability of selected plants, or plant communities, to effectively uptake, accumulate and tolerate targeted contaminants. Heavy metals, specifically cadmium (Cd), are not essential nutrients to plants. However, chemically similar zinc (Zn) is a micronutrient and is actively taken up by hyperaccumulators. For this reason, the mechanisms involved in uptake of Cd parallel those of Zn. Ideally, Cd would be allocated to the stem, leaf, and/or flower, where it becomes harvestable. Our modeling work simulates the uptake and the storage of Cd in a growing hyperaccumulator. After uptake, Cd is partitioned between adsorption to plant tissue and upward movement to leaves driven by transpiration. Uptake, adsorption and transport are also regulated by phytotoxicity. Simulations suggest that a young plant with small biomass can quickly reach phytotoxicity, which shuts down the normal operation of the plant. Conversely, mature plants on a mildly contaminated site, if harvested before the plants die due to phytotoxicity or natural cause, not only survive but may occasionally thrive. The immediate aim is to estimate the effectiveness and limitations of Cd uptake by hyperaccumulators. The eventual goal of this study is to expand the model in spatial and temporal scales, from individual plants to the community scale, and from one harvest interval to several generations. Understanding the interface between physical and biological processes, specifically the uptake and release of contaminants, provides scientists and engineers tools to assess whether phytoremediation is a reasonable strategy for a given environment.

Proton exchange membranes for application in fuel cells: grafted silica/SPEEK nanocomposite elaboration and characterization.

PubMed

Reinholdt, Marc X; Kaliaguine, Serge

2010-07-06

Hydrogen technologies and especially fuel cells are key components in the battle to find alternate sources of energy to the highly polluting and economically constraining fossil fuels in an aim to preserve the environment. The present paper shows the synthesis of surface functionalized silica nanoparticles, which are used to prepare grafted silica/SPEEK nanocomposite membranes. The nanoparticles are grafted either with hexadecylsilyl or aminopropyldimethylsilyl moieties or both. The synthesized particles are analyzed using XRD, NMR, TEM, and DLS to collect information on the nature of the particles and the functional groups, on the particle sizes, and on the hydrophilic/hydrophobic character. The composite membranes prepared using the synthesized particles and two SPEEK polymers with sulfonation degrees of 69.4% and 85.0% are characterized for their proton conductivity and water uptake properties. The corresponding curves are very similar for the composites prepared with both polymers and the nanoparticles bearing the two functional groups. The composites prepared with the nanoparticles bearing solely the aminopropyldimethylsilyl moiety exhibit lower conductivity and water uptake, possibly due to higher interaction of the polymer sulfonic acid sites with the amine groups. The composites prepared with the nanoparticles bearing solely the hexadecylsilyl moiety were not further investigated because of very high particles segregation. A study of the proton conductivity as a function of temperature was performed on selected membranes and showed that nanocomposites made with nanoparticles bearing both functional moieties have a higher conductivity at higher temperatures.

A simplified method for active-site titration of lipases immobilised on hydrophobic supports.

PubMed

Nalder, Tim D; Kurtovic, Ivan; Barrow, Colin J; Marshall, Susan N

2018-06-01

The aim of this work was to develop a simple and accurate protocol to measure the functional active site concentration of lipases immobilised on highly hydrophobic supports. We used the potent lipase inhibitor methyl 4-methylumbelliferyl hexylphosphonate to titrate the active sites of Candida rugosa lipase (CrL) bound to three highly hydrophobic supports: octadecyl methacrylate (C18), divinylbenzene crosslinked methacrylate (DVB) and styrene. The method uses correction curves to take into account the binding of the fluorophore (4-methylumbelliferone, 4-MU) by the support materials. We showed that the uptake of the detection agent by the three supports is not linear relative to the weight of the resin, and that the uptake occurs in an equilibrium that is independent of the total fluorophore concentration. Furthermore, the percentage of bound fluorophore varied among the supports, with 50 mg of C18 and styrene resins binding approximately 64 and 94%, respectively. When the uptake of 4-MU was calculated and corrected for, the total 4-MU released via inhibition (i.e. the concentration of functional lipase active sites) could be determined via a linear relationship between immobilised lipase weight and total inhibition. It was found that the functional active site concentration of immobilised CrL varied greatly among different hydrophobic supports, with 56% for C18, compared with 14% for DVB. The described method is a simple and robust approach to measuring functional active site concentration in immobilised lipase samples. Copyright © 2018 Elsevier Inc. All rights reserved.

Magnetic iron oxide and manganese-doped iron oxide nanoparticles for the collection of alpha-emitting radionuclides from aqueous solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Hara, Matthew J.; Carter, Jennifer C.; Warner, Cynthia L.

Magnetic nanoparticles are well known to possess chemically active surfaces and high surface areas that can be employed to extract a range of ions from aqueous solutions. Additionally, their paramagnetic property provides a convenient means for bulk collection of the material from solution after the targeted ions have been adsorbed. Herein, two nanoscale amphoteric metal oxides, each possessing useful magnetic attributes, were evaluated for their ability to collect both naturally occurring radioactive isotopes (polonium (Po), radium (Ra), and uranium (U)) as well as the transuranic element americium (Am) from a suite of naturally occurring aqueous matrices. The nanomaterials include commerciallymore » available paramagnetic magnetite (Fe3O4) and magnetite that was modified to incorporate manganese (Mn) into the crystal structure. The chemical stability of these nanomaterials was evaluated in Hanford Site, WA ground water between the natural pH (~8) and pH 1 (acidified with HCl). Whereas the magnetite was observed to have good stability over the pH range, the Mn-doped material was observed to leach Mn at low pH. The materials were evaluated in parallel to characterize their uptake performance of the aforementioned alpha-emitting radionuclide spikes from Hanford Site ground water across a range of pH (from ~8 down to 2). In addition, radiotracer uptake experiments were performed on Columbia River water, seawater, and human urine at their natural pH and at pH 2. Despite the observed leaching of Mn from the Mn-doped nanomaterial in the lower pH range, it exhibited generally superior analyte extraction performance compared to the magnetite, and analyte uptake was observed across a broader pH range. The uptake behavior of the various radiotracers on these two materials at different pH levels can generally be explained by the amphoteric nature of the nanoparticle surfaces. Finally, the rate of sorption of the radiotracers on the two materials in unacidified groundwater was evaluated. The uptake curves generally indicate that equilibrium is obtained within a few minutes, which is attributed to the high surface areas of the nanomaterials and the high level of dispersion in the liquids. Overall, the results indicate that these nanomaterials may have the potential to be employed for a range of applications to extract radionuclides from aqueous solutions. These applications may include analytical chemistry, waste water treatment and remediation, mining, and in vitro radiobioassay.« less

Does biofilm contribute to diel cycling of Zn in High Ore Creek, Montana?

USGS Publications Warehouse

Morris, J.M.; Nimick, D.A.; Farag, A.M.; Meyer, J.S.

2005-01-01

Concentrations of metals cycle daily in the water column of some mining-impacted streams in the Rocky Mountains of the western USA. We hypothesized that biofilm in High Ore Creek, Montana, USA, sorbs and releases Zn on a diel cycle, and this uptake-and-release cycle controls the total and dissolved (0.45-??m filtered) Zn concentrations. We collected water samples from three sites (upstream, middle and downstream at 0, 350 and 650 m, respectively) along a 650-m reach of High Ore Creek during a 47-h period in August 2002 and from the upstream and downstream sites during a 24-h period in August 2003; we also collected biofilm samples at these sites. In 2002 and 2003, total and dissolved Zn concentrations did not exhibit a diel cycle at the upstream sampling site, which was ???30 m downstream from a settling pond through which the creek flows. However, total and dissolved Zn concentrations exhibited a diel cycle at the middle and downstream sampling sites, with the highest Zn concentrations occurring at dawn and the lowest Zn concentrations occurring during late afternoon (>2-fold range of concentrations at the downstream site). Based on (1) concentrations of Zn in biofilm at the three sites and (2) results of streamside experiments that demonstrated Zn uptake and release by nai??ve biofilm during the light and dark hours of a photocycle, respectively, we conclude that Zn uptake in photosynthetic biofilms could contribute a large percentage to the cycling of Zn concentrations in the water column in High Ore Creek. ?? Springer 2005.

An exposure system for measuring nasal and lung uptake of vapors in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahl, A.R.; Brookins, L.K.; Gerde, P.

1995-12-01

Inhaled gases and vapors often produce biological damage in the nasal cavity and lower respiratory tract. The specific site within the respirator tract at which a gas or vapor is absorbed strongly influences the tissues at risk to potential toxic effects; to predict or to explain tissue or cell specific toxicity of inhaled gases or vapors, the sites at which they are absorbed must be known. The purpose of the work reported here was to develop a system for determining nose and lung absorption of vapors in rats, an animal commonly used in inhalation toxicity studies. In summary, the exposuremore » system described allows us to measure in the rate: (1) nasal absorption and desorption of vapors; (2) net lung uptake of vapors; and (3) the effects of changed breathing parameters on vapor uptake.« less

Zinc isotope investigation of surface and pore waters in a mountain watershed impacted by acid rock drainage.

PubMed

Aranda, Suzan; Borrok, David M; Wanty, Richard B; Balistrieri, Laurie S

2012-03-15

The pollution of natural waters with metals derived from the oxidation of sulfide minerals like pyrite is a global environmental problem. However, the metal loading pathways and transport mechanisms associated with acid rock drainage reactions are often difficult to characterize using bulk chemical data alone. In this study, we evaluated the use of zinc (Zn) isotopes to complement traditional geochemical tools in the investigation of contaminated waters at the former Waldorf mining site in the Rocky Mountains, Colorado, U.S.A. Geochemical signatures and statistical analysis helped in identifying two primary metal loading pathways at the Waldorf site. The first was characterized by a circumneutral pH, high alkalinity, and high Zn/Cd ratios. The second was characterized by acidic pHs and low Zn/Cd ratios. Zinc isotope signatures in surface water samples collected across the site were remarkably similar (the δ(66)Zn, relative to JMC 3-0749-L, for most samples ranged from 0.20 to 0.30‰±0.09‰ 2σ). This probably suggests that the ultimate source of Zn is consistent across the Waldorf site, regardless of the metal loading pathway. The δ(66)Zn of pore water samples collected within a nearby metal-impacted wetland area, however, were more variable, ranging from 0.20 to 0.80‰±0.09‰ 2σ. Here the Zn isotopes seemed to reflect differences in groundwater flow pathways. However, a host of secondary processes might also have impacted Zn isotopes, including adsorption of Zn onto soil components, complexation of Zn with dissolved organic matter, uptake of Zn into plants, and the precipitation of Zn during the formation of reduced sulfur species. Zinc isotope analysis proved useful in this study; however, the utility of this isotopic tool would improve considerably with the addition of a comprehensive experimental foundation for interpreting the complex isotopic relationships found in soil pore waters. Copyright © 2012 Elsevier B.V. All rights reserved.

Is integrated 18F-FDG PET/MRI superior to 18F-FDG PET/CT in the differentiation of incidental tracer uptake in the head and neck area?

PubMed

Schaarschmidt, Benedikt Michael; Gomez, Benedikt; Buchbender, Christian; Grueneisen, Johannes; Nensa, Felix; Sawicki, Lino Morris; Ruhlmann, Verena; Wetter, Axel; Antoch, Gerald; Heusch, Philipp

2017-01-01

We aimed to investigate the accuracy of 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (18F-FDG PET/MRI) compared with contrast-enhanced 18F-FDG PET/computed tomography (PET/CT) for the characterization of incidental tracer uptake in examinations of the head and neck. A retrospective analysis of 81 oncologic patients who underwent contrast-enhanced 18F-FDG PET/CT and subsequent PET/MRI was performed by two readers for incidental tracer uptake. In a consensus reading, discrepancies were resolved. Each finding was either characterized as most likely benign, most likely malignant, or indeterminate. Using all available clinical information including results from histopathologic sampling and follow-up examinations, an expert reader classified each finding as benign or malignant. McNemar's test was used to compare the performance of both imaging modalities in characterizing incidental tracer uptake. Forty-six lesions were detected by both modalities. On PET/CT, 27 lesions were classified as most likely benign, one as most likely malignant, and 18 as indeterminate; on PET/MRI, 31 lesions were classified as most likely benign, one lesion as most likely malignant, and 14 as indeterminate. Forty-three lesions were benign and one lesion was malignant according to the reference standard. In two lesions, a definite diagnosis was not possible. McNemar's test detected no differences concerning the correct classification of incidental tracer uptake between PET/CT and PET/MRI (P = 0.125). In examinations of the head and neck area, incidental tracer uptake cannot be classified more accurately by PET/MRI than by PET/CT.

Long-Term Management Strategy for Dredged Material Disposal for Naval Facilities at Pearl Harbor, Hawaii Phase III - Analysis of Alternatives and Development of an LTMS

DTIC Science & Technology

2000-03-01

are needed to restrict contaminants losses via the leachate and volatilization pathways. Plant uptake testing indicated a potential need to restrict...or control future use of the site, to amend the material with soil additives, to phytoremediate , or to provide a final surface cover of clean...initial release including toxicity and bioaccumulation, effluent, runoff, leachate , plant uptake, upland and aquatic animal uptake, and

Cost minimization analysis and utility of pretreatment and posttreatment total body iodine-131 scans in patients with thyroid carcinoma.

PubMed

Grigsby, P

1998-03-01

The purpose of this study was to evaluate the utility of posttreatment total body iodine-131 (I-131) scans. The records of 63 consecutive patients with thyroid carcinoma treated with surgery and postoperative I-131 were reviewed. Patients underwent a postoperative diagnostic total body I-131 scan. Subsequently, patients received therapeutic administration of I-131. Posttreatment total body I-131 scans were performed. The postoperative diagnostic total body I-131 scans revealed uptake in the neck in all 63 patients and also demonstrated lung and mediastinal uptake in 7 patients with known sites of metastatic disease. The posttreatment total body I-131 scans also revealed neck uptake in all patients and demonstrated uptake in the lung and mediastinum in those with known metastasis to those sites. Additional foci of neck uptake were revealed on the posttreatment total body I-131 scans in six patients. Stepwise logistic regression was performed to identify prognostic factors predictive of additional foci of uptake on the posttreatment total body I-131 scans compared with the pretreatment diagnostic total body I-131 scans. Variables found to correlate significantly with additional uptake on the posttreatment total body I-131 scans were tumor size > or = 2 cm, follicular histology, and multifocal disease. Posttreatment total body I-131 scans yielded additional information in only 10% (6 of 63) of the study patient population treated with postoperative I-131 for thyroid carcinoma. Therefore, the cost, and the associated inconvenience to the patient, of performing a posttreatment total body I-131 scan can be eliminated for most patients.

Ozone uptake, water loss and carbon exchange dynamics in annually drought-stressed Pinus ponderosa forests: measured trends and parameters for uptake modeling.

PubMed

Panek, Jeanne A

2004-03-01

This paper describes 3 years of physiological measurements on ponderosa pine (Pinus ponderosa Dougl. ex Laws.) growing along an ozone concentration gradient in the Sierra Nevada, California, including variables necessary to parameterize, validate and modify photosynthesis and stomatal conductance algorithms used to estimate ozone uptake. At all sites, gas exchange was under tight stomatal control during the growing season. Stomatal conductance was strongly correlated with leaf water potential (R2=0.82), which decreased over the growing season with decreasing soil water content (R2=0.60). Ozone uptake, carbon uptake, and transpirational water loss closely followed the dynamics of stomatal conductance. Peak ozone and CO2 uptake occurred in early summer and declined progressively thereafter. As a result, periods of maximum ozone uptake did not correspond to periods of peak ozone concentration, underscoring the inappropriateness of using current metrics based on concentration (e.g., SUM0, W126 and AOT40) for assessing ozone exposure risk to plants in this climate region. Both Jmax (maximum CO2-saturated photosynthetic rate, limited by electron transport) and Vcmax (maximum rate of Rubisco-limited carboxylation) increased toward the middle of the growing season, then decreased in September. Intrinsic water-use efficiency rose with increasing drought stress, as expected. The ratio of Jmax to Vcmax was similar to literature values of 2.0. Nighttime respiration followed a Q10 of 2.0, but was significantly higher at the high-ozone site. Respiration rates decreased by the end of the summer as a result of decreased metabolic activity and carbon stores.

Antenatal glucocorticoid treatment alters Na+ uptake in renal proximal tubule cells from adult offspring in a sex-specific manner.

PubMed

Su, Yixin; Bi, Jianli; Pulgar, Victor M; Figueroa, Jorge; Chappell, Mark; Rose, James C

2015-06-01

We have shown a sex-specific effect of fetal programming on Na(+) excretion in adult sheep. The site of this effect in the kidney is unknown. Therefore, we tested the hypothesis that renal proximal tubule cells (RPTCs) from adult male sheep exposed to betamethasone (Beta) before birth have greater Na(+) uptake than do RPTCs from vehicle-exposed male sheep and that RPTCs from female sheep similarly exposed are not influenced by antenatal Beta. In isolated RPTCs from 1- to 1.5-yr-old male and female sheep, we measured Na(+) uptake under basal conditions and after stimulation with ANG II. To gain insight into the mechanisms involved, we also measured nitric oxide (NO) levels, ANG II receptor mRNA levels, and expression of Na(+)/H(+) exchanger 3. Basal Na(+) uptake increased more in cells from Beta-exposed male sheep than in cells from vehicle-exposed male sheep (400% vs. 300%, P < 0.00001). ANG II-stimulated Na(+) uptake was also greater in cells from Beta-exposed males. Beta exposure did not increase Na(+) uptake by RPTCs from female sheep. NO production was suppressed more by ANG II in RPTCs from Beta-exposed males than in RPTCs from either vehicle-exposed male or female sheep. Our data suggest that one site of the sex-specific effect of Beta-induced fetal programming in the kidney is the RPTC and that the enhanced Na(+) uptake induced by antenatal Beta in male RPTCs may be related to the suppression of NO in these cells. Copyright © 2015 the American Physiological Society.

Localization of serotoni (5-hydroxytryptamine, 5-HT) with partial purification and characterization of a serotonin binding protein in the intestinal tissue of the nematode Ascaris suum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, R.E.

1989-01-01

An intracellular 5-HT binding protein (SBP) from intestinal tissue was partially purified and characterized. Binding of ({sup 3}H) 5-HT to the protein appeared to be Fe{sup +2}-sensitive and maximal (20.8pmol/mg protein) at 5 {times} 10{sup {minus}4}M Fe{sup +2} and 10{sup {minus}7}M ({sup 3}H) 5-HT. There were two 5-HT binding sites present at optimum Fe{sup +2} concentrations. The Bmax values of these sites were more sensitive to Fe{sup +2} than Kd values. Sulfhydryl reducing agents, cation chelators, Fe{sup +3}, Ca{sup +2} and antagonists of 5-HT uptake and storage inhibited binding of 5-HT to SBP. Gel exclusion chromatography indicated the presence ofmore » a 45Kda SBP that in 5 {times} 10{sup {minus}5}M Fe{sup +2} may form aggregates ranging in size from approximately 80 to >1000Kda. The data indicate these in vitro aggregates may correspond to the electron-opaque patches observed in situ. Ascaris suum may provide a model system to further elucidate the physiological role of analogous serotonin binding proteins that have been identified in mammalian systems.« less

Diurnal and Seasonal Variations of Eddy-Covariance Carbon Dioxide Fluxes Above an Urban Wetland, Partitioned by Vegetation Cover

NASA Astrophysics Data System (ADS)

Schafer, K. V.; Duman, T.

2017-12-01

The New Jersey Meadowlands are an urban brackish marsh with a long history of human activity causing disturbances and alterations. Carbon emissions were measured from two sites in the Meadowlands, a natural site and a restored site, using eddy-covariance (EC) from 2014 to 2016. At each site, the EC towers were placed at the interface of two vegetation covers, allowing capturing this aspect of the wetland's heterogeneity. Using footprint modeling and light response curves we were able to partition measured fluxes between vegetation cover types and compare CO2 fluxes from patches of invasive versus native wetland vegetation communities. We show that further separating the data into seasonal and diurnal fluxes reveals patterns in CO2 fluxes that allow determining the nature of each vegetation cover as a source or sink for CO2. Our results also show that CO2 emissions from the restored wetland are significantly higher than the natural wetland. Areas of invasive Phragmites australis at the natural site had the lowest CO2 release rates during winter. These were consistently lower in magnitude than summer daytime uptake, therefore making this part of the wetland a CO2 sink. Areas planted with native Spartina alterniflora at the restored site had the largest uptake during daytime, therefore seemingly justifying restoration activities. However, they also had the highest emission rates during summer nighttime, and therefore the daily summer net uptake was not the highest compared with other vegetation covers. Furthermore, emissions from the restored site during winter were larger compared to the natural site, indicating that restoration activities might have led to a significant increase of carbon release from the wetland. Thus, during the study period the restored wetland acted as a carbon source.

GZ-793A, a lobelane analog, interacts with the vesicular monoamine transporter-2 to inhibit the effect of methamphetamine

PubMed Central

Horton, David B.; Nickell, Justin R.; Zheng, Guangrong; Crooks, Peter A.; Dwoskin, Linda P.

2013-01-01

GZ-793A inhibits methamphetamine-evoked dopamine release from striatal slices and methamphetamine self-administration in rats. GZ-793A potently and selectively inhibits dopamine uptake at the vesicular monoamine transporter-2 (VMAT2). The present study determined GZ-793A’s ability to evoke [3H]dopamine release and inhibit methamphetamine-evoked [3H]dopamine release from isolated striatal synaptic vesicles. Results show GZ-793A concentration-dependent [3H]dopamine release; nonlinear regression revealed a two-site model of interaction with VMAT2 (High- and Low-EC50 = 15.5 nM and 29.3 µM, respectively). Tetrabenazine and reserpine completely inhibited the GZ-793A-evoked [3H]dopamine release, however, only at the High-affinity site. Low concentrations of GZ-793A that interact with the extravesicular dopamine uptake site and the High-affinity intravesicular DA release site also inhibited methamphetamine-evoked [3H]dopamine release from synaptic vesicles. A rightward shift in the methamphetamine concentration-response was evident with increasing concentrations of GZ-793A, and the Schild regression slope was 0.49±0.08, consistent with surmountable allosteric inhibition. These results support a hypothetical model of GZ-793A interaction at more than one site on VMAT2 protein, which explains its potent inhibition of dopamine uptake, dopamine release via a High-affinity tetrabenazine- and reserpine-sensitive site, dopamine release via a Low-affinity tetrabenazine- and reserpine-insensitive site, and low-affinity interaction with the dihydrotetrabenazine binding site on VMAT2. GZ-793A-inhibition of the effects of methamphetamine supports its potential as a therapeutic agent for the treatment of methamphetamine abuse. PMID:23875622

Quantifying stream nutrient uptake from ambient to saturation with instantaneous tracer additions

NASA Astrophysics Data System (ADS)

Covino, T. P.; McGlynn, B. L.; McNamara, R.

2009-12-01

Stream nutrient tracer additions and spiraling metrics are frequently used to quantify stream ecosystem behavior. However, standard approaches limit our understanding of aquatic biogeochemistry. Specifically, the relationship between in-stream nutrient concentration and stream nutrient spiraling has not been characterized. The standard constant rate (steady-state) approach to stream spiraling parameter estimation, either through elevating nutrient concentration or adding isotopically labeled tracers (e.g. 15N), provides little information regarding the stream kinetic curve that represents the uptake-concentration relationship analogous to the Michaelis-Menten curve. These standard approaches provide single or a few data points and often focus on estimating ambient uptake under the conditions at the time of the experiment. Here we outline and demonstrate a new method using instantaneous nutrient additions and dynamic analyses of breakthrough curve (BTC) data to characterize the full relationship between spiraling metrics and nutrient concentration. We compare the results from these dynamic analyses to BTC-integrated, and standard steady-state approaches. Our results indicate good agreement between these three approaches but we highlight the advantages of our dynamic method. Specifically, our new dynamic method provides a cost-effective and efficient approach to: 1) characterize full concentration-spiraling metric curves; 2) estimate ambient spiraling metrics; 3) estimate Michaelis-Menten parameters maximum uptake (Umax) and the half-saturation constant (Km) from developed uptake-concentration kinetic curves, and; 4) measure dynamic nutrient spiraling in larger rivers where steady-state approaches are impractical.

Size of submicrometric and nanometric particles affect cellular uptake and biological activity of macrophages in vitro.

PubMed

Leclerc, L; Rima, W; Boudard, D; Pourchez, J; Forest, V; Bin, V; Mowat, P; Perriat, P; Tillement, O; Grosseau, P; Bernache-Assollant, D; Cottier, M

2012-08-01

Micrometric and nanometric particles are increasingly used in different fields and may exhibit variable toxicity levels depending on their physicochemical characteristics. The aim of this study was to determine the impact of the size parameter on cellular uptake and biological activity, working with well-characterized fluorescent particles. We focused our attention on macrophages, the main target cells of the respiratory system responsible for the phagocytosis of the particles. FITC fluorescent silica particles of variable submicronic sizes (850, 500, 250 and 150 nm) but with similar surface coating (COOH) were tailored and physico-chemically characterized. These particles were then incubated with the RAW 264.7 macrophage cell line. After microscopic observations (SEM, TEM, confocal), a quantitative evaluation of the uptake was carried out. Fluorescence detected after a quenching with trypan blue allows us to distinguish and quantify entirely engulfed fluorescent particles from those just adhering to the cell membrane. Finally, these data were compared to the in vitro toxicity assessed in terms of cell damage, inflammation and oxidative stress (evaluated by LDH release, TNF-α and ROS production respectively). Particles were well characterized (fluorescence, size distribution, zeta potential, agglomeration and surface groups) and easily visualized after cellular uptake using confocal and electron microscopy. The number of internalized particles was precisely evaluated. Size was found to be an important parameter regarding particles uptake and in vitro toxicity but this latter strongly depends on the particles doses employed.

Site-specific conjugation of monodispersed DOTA-PEGn to a thiolated diabody reveals the effect of increasing peg size on kidney clearance and tumor uptake with improved 64-copper PET imaging.

PubMed

Li, Lin; Crow, Desiree; Turatti, Fabio; Bading, James R; Anderson, Anne-Line; Poku, Erasmus; Yazaki, Paul J; Carmichael, Jenny; Leong, David; Wheatcroft, David; Wheatcroft, Michael P; Raubitschek, Andrew A; Hudson, Peter J; Colcher, David; Shively, John E

2011-04-20

Optimal PET imaging of tumors with radiolabeled engineered antibodies requires, among other parameters, matching blood clearance and tumor uptake with the half-life of the engineered antibody. Although diabodies have favorable molecular sizes (50 kDa) for rapid blood clearance (t(1/2) = 30-60 min) and are bivalent, thereby increasing tumor uptake, they exhibit substantial kidney uptake as their major route of clearance, which is especially evident when they are labeled with the PET isotope (64)Cu (t(1/2) = 12 h). To overcome this drawback, diabodies may be conjugated to PEG, a modification that increases the apparent molecular size of the diabody and reduces kidney uptake without adversely affecting tumor uptake or the tumor to blood ratio. We show here that site-specific attachment of monodispersed PEGn of increasing molecular size (n = 12, 24, and 48) can uniformly increase the apparent molecular size of the PEG-diabody conjugate, decrease kidney uptake, and increase tumor uptake, the latter due to the increased residence time of the conjugate in the blood. Since the monodispersed PEGs were preconjugated to the chelator DOTA, the conjugates were able to bind radiometals such as (111)In and (64)Cu that can be used for SPECT and PET imaging, respectively. To allow conjugation of the DOTA-PEG to the diabody, the DOTA-PEG incorporated a terminal cysteine conjugated to a vinyl sulfone moiety. In order to control the conjugation chemistry, we have engineered a surface thiolated diabody that incorporates two cysteines per monomer (four per diabody). The thiolated diabody was expressed and purified from bacterial fermentation and only needs to be reduced prior to conjugation to the DOTA-PEGn-Cys-VS. This novel imaging agent (a diabody with DOTA-PEG48-Cys-VS attached to introduced thiols) gave up to 80%ID/g of tumor uptake with a tumor to blood ratio (T/B) of 8 at 24 h when radiolabeled with (111)In and 37.9% ID/g of tumor uptake (T/B = 8) at 44 h when radiolabeled with (64)Cu in PET imaging in an animal model. Tumor uptake was significantly improved from the 50% ID/g at 24 h observed with diabodies that were pegylated on surface lysine residues. Importantly, there was no loss of immunoreactivity of the site-specific Cys-conjugated diabody to its antigen (TAG-72) compared to the parent, unconjugated diabody. We propose that thiolated diabodies conjugated to DOTAylated monodisperse PEGs have the potential for superior SPECT and PET imaging in a clinical setting.

Characterization of strychnine-sensitive glycine receptor in the intact frog retina: modulation by protein kinases.

PubMed

Salceda, Rocío; Aguirre-Ramirez, Marisela

2005-03-01

We studied 3H-glycine and 3H-strychnine specific binding to glycine receptor (GlyR) in intact isolated frog retinas. To avoid glycine binding to glycine uptake sites, experiments were performed at low ligand concentrations in a sodium-free medium. The binding of both radiolabeled ligands was saturated. Scatchard analysis of bound glycine and strychnine revealed a KD of 2.5 and 2.0 microM, respectively. Specific binding of glycine was displaced by beta-alanine, sarcosine, and strychnine. Strychnine binding was displaced 50% by glycine, and sarcosine. Properties of the strychnine-binding site in the GlyR were modified by sarcosine. Binding of both radioligands was considerably reduced by compounds that inhibit or activate adenylate cyclase and increased cAMP levels. A phorbol ester activator of PKC remarkably decreased glycine and strychnine binding. These results suggest modulation of GlyR in response to endogenous activation of protein kinases A and C, as well as protein phosphorylation modulating GlyR function in retina.

PROCEEDINGS ON SYNCHROTRON RADIATION: Transfer characterization of sulfur from coal-burning emission to plant leaves by PIXE and XANES

NASA Astrophysics Data System (ADS)

Bao, Liang-Man; Zhang, Gui-Lin; Zhang, Yuan-Xim; Li, Yan; Lin, Jun; Liu, Wei; Cao, Qing-Chen; Zhao, Yi-Dong; Ma, Chen-Yan; Han, Yong

2009-11-01

The impact of coal-burning emission on sulfur in camphor leaves was investigated using Proton Induced X-ray Emission (PIXE) and synchrotron radiation technique X-ray Absorption Near-Edge Structure (XANES) spectroscopy. The PIXE results show that the sulfur concentrations in the leaves collected at the polluted site are significantly higher than those in controls. The Sulfur XANES spectra show the presence of organic (disulfides, thiols, thioethers, sulfonates and sulfoxides) and inorganic sulfur (sulfates) in the leaves. The inorganic sulfur in the leaves of camphor tree polluted by coal combustion is 15% more than that of the control site. The results suggest that the long-term coal-burning pollution resulted in an enhanced content of the total sulfur and sulfate in the leaves, and the uptake of sulfur by leaves had exceeded the metabolic requirement of plants and the excess of sulfur was stored as SO2-4. It can monitor the sulfur pollution in atmosphere.

Positive Newborn Screen for Methylmalonic Aciduria Identifies the First Mutation in TCblR/CD320, the Gene for Cellular Uptake of Transcobalamin-bound Vitamin B12

PubMed Central

Quadros, Edward V.; Lai, Shao-Chiang; Nakayama, Yasumi; Sequeira, Jeffrey M.; Hannibal, Luciana; Wang, Sihe; Jacobsen, Donald W.; Fedosov, Sergey; Wright, Erica; Gallagher, Renata C.; Anastasio, Natascia; Watkins, David; Rosenblatt, David S.

2010-01-01

Elevated methylmalonic acid in five asymptomatic newborns whose fibroblasts showed decreased uptake of transcobalamin-bound cobalamin (holo-TC), suggested a defect in the cellular uptake of cobalamin. Analysis of TCblR/CD320, the gene for the receptor for cellular uptake of holo-TC, identified a homozygous single codon deletion, c.262_264GAG (p.E88del), resulting in the loss of a glutamic acid residue in the low-density lipoprotein receptor type A-like domain. Inserting the codon by site-directed mutagenesis fully restored TCblR function. PMID:20524213

Caffeine inhibition of aflatoxin synthesis: probable site of action.

PubMed Central

Buchanan, R L; Lewis, D F

1984-01-01

Aflatoxin production by pregrown cultures of Aspergillus parasiticus was completely inhibited by incorporation of 2 mg of caffeine per ml into the medium. This was accompanied by a decrease in glucose utilization and an inhibition of oxygen uptake and carbon dioxide evolution. Enzyme analyses indicated no significant differences in specific activities on glucose-6-phosphate dehydrogenase, mannitol dehydrogenase, phosphofructokinase, fructose 1,6-diphosphatase, pyruvate kinase, or malate dehydrogenase. Glucose uptake kinetics indicated a linear dose-related inhibition of glucose uptake. It appears likely that caffeine inhibits aflatoxin synthesis by restricting the uptake of carbohydrates which are ultimately used by the mold to synthesize this family of mycotoxins. PMID:6331311

Enhancing outreach for persons with serious mental illness: 12-month results from a cluster randomized trial of an adaptive implementation strategy.

PubMed

Kilbourne, Amy M; Almirall, Daniel; Goodrich, David E; Lai, Zongshan; Abraham, Kristen M; Nord, Kristina M; Bowersox, Nicholas W

2014-12-28

Few implementation strategies have been empirically tested for their effectiveness in improving uptake of evidence-based treatments or programs. This study compared the effectiveness of an immediate versus delayed enhanced implementation strategy (Enhanced Replicating Effective Programs (REP)) for providers at Veterans Health Administration (VA) outpatient facilities (sites) on improved uptake of an outreach program (Re-Engage) among sites not initially responding to a standard implementation strategy. One mental health provider from each U.S. VA site (N = 158) was initially given a REP-based package and training program in Re-Engage. The Re-Engage program involved giving each site provider a list of patients with serious mental illness who had not been seen at their facility for at least a year, requesting that providers contact these patients, assessing patient clinical status, and where appropriate, facilitating appointments to VA health services. At month 6, sites considered non-responsive (N = 89, total of 3,075 patients), defined as providers updating documentation for less than <80% of patients on their list, were randomized to two adaptive implementation interventions: Enhanced REP (provider coaching; N = 40 sites) for 6 months followed by Standard REP for 6 months; versus continued Standard REP (N = 49 sites) for 6 months followed by 6 months of Enhanced REP for sites still not responding. Outcomes included patient-level Re-Engage implementation and utilization. Patients from sites that were randomized to receive Enhanced REP immediately compared to Standard REP were more likely to have a completed contact (adjusted OR = 2.13; 95% CI: 1.09-4.19, P = 0.02). There were no differences in patient-level utilization between Enhanced and Standard REP sites. Enhanced REP was associated with greater Re-Engage program uptake (completed contacts) among sites not responding to a standard implementation strategy. Further research is needed to determine whether national implementation of Facilitation results in tangible changes in patient-level outcomes. ISRCTN21059161.

Metabolism and insulin signaling in common metabolic disorders and inherited insulin resistance.

PubMed

Højlund, Kurt

2014-07-01

Type 2 diabetes, obesity and polycystic ovary syndrome (PCOS) are common metabolic disorders which are observed with increasing prevalences, and which are caused by a complex interplay between genetic and environmental factors, including increased calorie intake and physical inactivity. These metabolic disorders are all characterized by reduced plasma adiponectin and insulin resistance in peripheral tissues. Quantitatively skeletal muscle is the major site of insulin resistance. Both low plasma adiponectin and insulin resistance contribute to an increased risk of type 2 diabetes and cardiovascular disease. In several studies, we have investigated insulin action on glucose and lipid metabolism, and at the molecular level, insulin signaling to glucose transport and glycogen synthesis in skeletal muscle from healthy individuals and in obesity, PCOS and type 2 diabetes. Moreover, we have described a novel syndrome characterized by postprandial hyperinsulinemic hypoglycemia and insulin resistance. This syndrome is caused by a mutation in the tyrosine kinase domain of the insulin receptor gene (INSR). We have studied individuals with this mutation as a model of inherited insulin resistance. Type 2 diabetes, obesity and PCOS are characterized by pronounced defects in the insulin-stimulated glucose uptake, in particular glycogen synthesis and to a lesser extent glucose oxidation, and the ability of insulin to suppress lipid oxidation. In inherited insulin resistance, however, only insulin action on glucose uptake and glycogen synthesis is impaired. This suggests that the defects in glucose and lipid oxidation in the common metabolic disorders are secondary to other factors. In young women with PCOS, the degree of insulin resistance was similar to that seen in middle-aged patients with type 2 diabetes. This supports the hypothesis of an unique pathogenesis of insulin resistance in PCOS. Insulin in physiological concentrations stimulates glucose uptake in human skeletal muscle in vivo by activation of the insulin signaling cascade to glucose transport through the enzymes IRS1, PI3K, Akt2, AS160/TBC1D4 and RAC1, and to glycogen synthesis through Akt2, inhibition of GSK3 and activation of glycogen synthase (GS) via dephosphorylation of serine residues in both the NH2-terminal (site 2+2a) and the COOH-terminal end (site 3a+3b). In type 2 diabetes, obesity and PCOS, there is, although with some variation from study to study, defects in insulin signaling through IRS1, PI3K, Akt2 and AS160/TBC1D4, which can explain reduced insulin action on glucose transport. In type 2 diabetes an altered intracellular distribution of SNAP23 and impaired activation of RAC1 also seem to play a role for reduced insulin action on glucose transport. In all common metabolic disorders, we observed an impaired insulin activation of GS, which seems to be caused by attenuated dephosphorylation of GS at site 2+2a, whereas as the inhibition of GSK3 and the dephosphorylation of GS at its target sites, site 3a+3a, appeared to be completely normal. In individuals with inherited insulin resistance, we observed largely the same defects in insulin action on IRS1, PI3K, Akt2 and GS, as well as a normal inhibition of GSK3 and dephosphorylation of GS at site 3a+3b. In these individuals, however, a markedly reduced insulin clearance seems to partially rescue insulin signaling to glucose transport and GS. Adiponectin is thought to improve insulin sensitivity primarily by increasing lipid oxidation through activation of the enzyme AMPK, and possibly via cross-talking of adiponectin with insulin signaling, and hence glucose transport and glycogen synthesis. We demonstrated a strong correlation between plasma adiponectin and insulin action on glucose disposal and glycogen synthesis in obesity, type 2 diabetes and PCOS. In individuals with inherited insulin resistance, plasma adiponectin was normal, but the correlation of adiponectin with insulin-stimulated glucose uptake and glycogen synthesis was at least equally strong. Moreover, we found a correlation between plasma adiponectin and insulin activation of GS. This result is supported by a number of recent studies of animal models and muscle cell lines, which have shown that adiponectin augments insulin action on enzymes in the insulin signaling cascade. In contrast, we observed no differences in the abundance or activity of AMPK in obesity, type 2 diabetes, PCOS or inherited insulin resistance. This indicates that reduced insulin sensitivity in these conditions is not mediated via abnormal AMPK activity. The results from these studies demonstrate that the well-established abnormalities in insulin action on glucose uptake and glycogen synthesis are reflected by defects in insulin signaling to these cellular processes in type 2 diabetes, obesity, and PCOS, and as expected also in inherited insulin resistance caused by a mutation in INSR. In common metabolic disorders, low plasma adiponectin may contribute to insulin resistance and defects in insulin signaling, whereas in inherited insulin resistance a normal plasma adiponectin and reduced insulin clearance could contribute to maintain a sufficient activation of the insulin signaling cascade. The insight gained from these studies have improved our understanding of the molecular mechanisms underlying insulin resistance in skeletal muscle of humans, and can form the basis for further studies, which can lead to the development of treatment that more directly targets insulin resistance, and hence reduce the risk of type 2 diabetes and cardiovascular disease.

Synergistically enhanced selective intracellular uptake of anticancer drug carrier comprising folic acid-conjugated hydrogels containing magnetite nanoparticles

NASA Astrophysics Data System (ADS)

Kim, Haneul; Jo, Ara; Baek, Seulgi; Lim, Daeun; Park, Soon-Yong; Cho, Soo Kyung; Chung, Jin Woong; Yoon, Jinhwan

2017-01-01

Targeted drug delivery has long been extensively researched since drug delivery and release at the diseased site with minimum dosage realizes the effective therapy without adverse side effects. In this work, to achieve enhanced intracellular uptake of anticancer drug carriers for efficient chemo-therapy, we have designed targeted multifunctional anticancer drug carrier hydrogels. Temperature-responsive poly(N-isopropylacrylamide) (PNIPAm) hydrogel core containing superparamagnetic magnetite nanoparticles (MNP) were prepared using precipitation polymerization, and further polymerized with amine-functionalized copolymer shell to facilitate the conjugation of targeting ligand. Then, folic acid, specific targeting ligand for cervical cancer cell line (HeLa), was conjugated on the hydrogel surface, yielding the ligand conjugated hybrid hydrogels. We revealed that enhanced intracellular uptake by HeLa cells in vitro was enabled by both magnetic attraction and receptor-mediated endocytosis, which were contributed by MNP and folic acid, respectively. Furthermore, site-specific uptake of the developed carrier was confirmed by incubating with several other cell lines. Based on synergistically enhanced intracellular uptake, efficient cytotoxicity and apoptotic activity of HeLa cells incubated with anticancer drug loaded hybrid hydrogels were successfully achieved. The developed dual-targeted hybrid hydrogels are expected to provide a platform for the next generation intelligent drug delivery systems.

Novel targets of the CbrAB/Crc carbon catabolite control system revealed by transcript abundance in Pseudomonas aeruginosa.

PubMed

Sonnleitner, Elisabeth; Valentini, Martina; Wenner, Nicolas; Haichar, Feth el Zahar; Haas, Dieter; Lapouge, Karine

2012-01-01

The opportunistic human pathogen Pseudomonas aeruginosa is able to utilize a wide range of carbon and nitrogen compounds, allowing it to grow in vastly different environments. The uptake and catabolism of growth substrates are organized hierarchically by a mechanism termed catabolite repression control (Crc) whereby the Crc protein establishes translational repression of target mRNAs at CA (catabolite activity) motifs present in target mRNAs near ribosome binding sites. Poor carbon sources lead to activation of the CbrAB two-component system, which induces transcription of the small RNA (sRNA) CrcZ. This sRNA relieves Crc-mediated repression of target mRNAs. In this study, we have identified novel targets of the CbrAB/Crc system in P. aeruginosa using transcriptome analysis in combination with a search for CA motifs. We characterized four target genes involved in the uptake and utilization of less preferred carbon sources: estA (secreted esterase), acsA (acetyl-CoA synthetase), bkdR (regulator of branched-chain amino acid catabolism) and aroP2 (aromatic amino acid uptake protein). Evidence for regulation by CbrAB, CrcZ and Crc was obtained in vivo using appropriate reporter fusions, in which mutation of the CA motif resulted in loss of catabolite repression. CbrB and CrcZ were important for growth of P. aeruginosa in cystic fibrosis (CF) sputum medium, suggesting that the CbrAB/Crc system may act as an important regulator during chronic infection of the CF lung.

Starch-coated magnetic liposomes as an inhalable carrier for accumulation of fasudil in the pulmonary vasculature.

PubMed

Nahar, Kamrun; Absar, Shahriar; Patel, Brijeshkumar; Ahsan, Fakhrul

2014-04-10

In this study, we tested the feasibility of magnetic liposomes as a carrier for pulmonary preferential accumulation of fasudil, an investigational drug for the treatment of pulmonary arterial hypertension (PAH). To develop an optimal inhalable formulation, various magnetic liposomes were prepared and characterized for physicochemical properties, storage stability and in vitro release profiles. Select formulations were evaluated for uptake by pulmonary arterial smooth muscle cells (PASMCs) - target cells - using fluorescence microscopy and HPLC. The efficacy of the magnetic liposomes in reducing hyperplasia was tested in 5-HT-induced proliferated PASMCs. The drug absorption profiles upon intratracheal administration were monitored in healthy rats. Optimized spherical liposomes - with mean size of 170 nm, zeta potential of -35mV and entrapment efficiency of 85% - exhibited an 80% cumulative drug release over 120 h. Fluorescence microscopic study revealed an enhanced uptake of liposomes by PASMCs under an applied magnetic field: the uptake was 3-fold greater compared with that observed in the absence of magnetic field. PASMC proliferation was reduced by 40% under the influence of the magnetic field. Optimized liposomes appeared to be safe when incubated with PASMCs and bronchial epithelial cells. Compared with plain fasudil, intratracheal magnetic liposomes containing fasudil extended the half-life and area under the curve by 27- and 14-fold, respectively. Magnetic-liposomes could be a viable delivery system for site-specific treatment of PAH. Copyright © 2014 Elsevier B.V. All rights reserved.

Fucosterol activates the insulin signaling pathway in insulin resistant HepG2 cells via inhibiting PTP1B.

PubMed

Jung, Hyun Ah; Bhakta, Himanshu Kumar; Min, Byung-Sun; Choi, Jae Sue

2016-10-01

Insulin resistance is a characteristic feature of type 2 diabetes mellitus (T2DM) and is characterized by defects in insulin signaling. This study investigated the modulatory effects of fucosterol on the insulin signaling pathway in insulin-resistant HepG2 cells by inhibiting protein tyrosine phosphatase 1B (PTP1B). In addition, molecular docking simulation studies were performed to predict binding energies, the specific binding site of fucosterol to PTP1B, and to identify interacting residues using Autodock 4.2 software. Glucose uptake was determined using a fluorescent D-glucose analogue and the glucose tracer 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxyglucose, and the signaling pathway was detected by Western blot analysis. We found that fucosterol enhanced insulin-provoked glucose uptake and conjointly decreased PTP1B expression level in insulin-resistant HepG2 cells. Moreover, fucosterol significantly reduced insulin-stimulated serine (Ser307) phosphorylation of insulin receptor substrate 1 (IRS1) and increased phosphorylation of Akt, phosphatidylinositol-3-kinase, and extracellular signal- regulated kinase 1 at concentrations of 12.5, 25, and 50 µM in insulin-resistant HepG2 cells. Fucosterol inhibited caspase-3 activation and nuclear factor kappa B in insulin-resistant hepatocytes. These results suggest that fucosterol stimulates glucose uptake and improves insulin resistance by downregulating expression of PTP1B and activating the insulin signaling pathway. Thus, fucosterol has potential for development as an anti-diabetic agent.

Minimizing antibody surface density on liposomes while sustaining cytokine-activated EC targeting.

PubMed

Almeda, Dariela; Wang, Biran; Auguste, Debra T

2015-02-01

Liposomes may be engineered to target inflamed endothelium by mimicking ligand-receptor interactions between leukocytes and cytokine-activated endothelial cells (ECs). The upregulation and assembly of vascular cell adhesion molecule-1 (VCAM1) and E-selectin on the cell membrane upon exposure to cytokines have shown potential for drug delivery vehicles to target sites of chronic endothelial inflammation, such as atherosclerosis and cancer. Herein, we characterized EC surfaces by measuring the E-selectin and VCAM1 surface densities and adhesion forces of aVCAM1 and aE-selectin to ECs. We quantified the antibody density, ratio, and diffusivity of liposomes to achieve significant binding and internalization. At 1 h, the 1:1 ratio of VCAM1:E-selectin antibodies was significantly higher than 1:0 and 0:1. Significant binding and uptake was achieved at aE-selectin densities as low as 400 molecules/μm(2). The highest levels of binding and uptake were achieved when using a 1:1 ratio of VCAM1:E-selectin antibodies at a density of 1000 molecules/μm(2); this density is 85% lower than previous reports. The binding and uptake of functionalized liposomes were reduced to levels comparable to IgG functionalized liposomes upon a 10-fold reduction in liposome membrane diffusivity. We conclude with a liposomal design that discriminates between healthy and inflamed endothelium while reducing antibody surface presentation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Seaweeds along KwaZulu-Natal coast of South Africa-3: elemental uptake by Ulva lactuca (Sea lettuce).

PubMed

Misheer, Natasha; Kindness, A; Jonnalagadda, S B

2006-01-01

The elemental uptake by Ulva lactuca (Sea lettuce), a marine macro-algae (chlorophyta, green alga) grown richly along KwaZulu-Natal coastline. The total elemental concentrations of seven important elements, namely manganese, iron, arsenic, boron, titanium, zinc and mercury, selected based on their abundance in U. lactuca were investigated for one year cycle (June 2002 to May 2003). The four selected sampling sites, Zinkwasi, Ballito, Treasure Beach and Park Ryrie are spread over 150 km wide along the KwaZulu-Natal coastline from North to South. The Ulva lectuca possess good manganese and arsenic accumulating ability and an excellent bio-indicator for most of the metals studied. A typical U. lectuca sample at Zinkwasi (in winter) recorded Mn (25.3 +/- 1.16 ppm), Fe (21.0 +/- 0.85 ppm), As (6.2 +/- 0.30 ppm), B (935 +/- 14 ppb), Ti (863 +/- 34 ppb), Zn (421 +/- 21 ppb), and Hg (61.3 +/- 1.2 ppb). The general trend found at all sites was high elemental concentrations in winter and a decrease in concentrations from winter to spring and summer. Iron uptake was lowest in summer and autumn at all sites. Ulva lactuca recorded highest mercury levels (>400 ppb) during the spring season at the Treasure Beach site near Durban.

Correlation of inflammation assessed by 18F-FDG PET, active mineral deposition assessed by 18F-fluoride PET, and vascular calcification in atherosclerotic plaque: a dual-tracer PET/CT study.

PubMed

Derlin, Thorsten; Tóth, Zoltán; Papp, László; Wisotzki, Christian; Apostolova, Ivayla; Habermann, Christian R; Mester, Janos; Klutmann, Susanne

2011-07-01

Formation and progression of atherosclerotic plaque is a dynamic and complex process involving various pathophysiologic steps including inflammation and calcification. The purpose of this study was to compare macrophage activity as determined by (18)F-FDG PET and ongoing mineral deposition as measured by (18)F-sodium fluoride PET in atherosclerotic plaque and to correlate these findings with calcified plaque burden as assessed by CT. Forty-five patients were examined by whole-body (18)F-FDG PET, (18)F-sodium fluoride PET, and CT. Tracer uptake in various arterial segments was analyzed both qualitatively and semiquantitatively by measuring the blood-pool-corrected standardized uptake value (target-to-background ratio [TBR]). The pattern of tracer uptake in atherosclerotic lesions was compared after color-coded multistudy image fusion of PET and CT studies. The Fisher exact test and the Spearman correlation coefficient r(s) were used for statistical analysis of image-based results and cardiovascular risk factors. Intra- and interrater reproducibility were evaluated using the Cohen κ. (18)F-sodium fluoride uptake was observed at 105 sites in 27 (60%) of the 45 study patients, and mean TBR was 2.3 ± 0.7. (18)F-FDG uptake was seen at 124 sites in 34 (75.6%) patients, and mean TBR was 1.5 ± 0.3. Calcified atherosclerotic lesions were observed at 503 sites in 34 (75.6%) patients. Eighty-one (77.1%) of the 105 lesions with marked (18)F-sodium fluoride uptake and only 18 (14.5%) of the 124 lesions with (18)F-FDG accumulation were colocalized with arterial calcification. Coincident uptake of both (18)F-sodium fluoride and (18)F-FDG was observed in only 14 (6.5%) of the 215 arterial lesions with radiotracer accumulation. PET/CT with (18)F-FDG and (18)F-sodium fluoride may allow evaluation of distinct pathophysiologic processes in atherosclerotic lesions and might provide information on the complex interactions involved in formation and progression of atherosclerotic plaque.

The Pitcher Plant Sarracenia purpurea Can Directly Acquire Organic Nitrogen and Short-Circuit the Inorganic Nitrogen Cycle

PubMed Central

Karagatzides, Jim D.; Butler, Jessica L.; Ellison, Aaron M.

2009-01-01

Background Despite the large stocks of organic nitrogen in soil, nitrogen availability limits plant growth in many terrestrial ecosystems because most plants take up only inorganic nitrogen, not organic nitrogen. Although some vascular plants can assimilate organic nitrogen directly, only recently has organic nitrogen been found to contribute significantly to the nutrient budget of any plant. Carnivorous plants grow in extremely nutrient-poor environments and carnivory has evolved in these plants as an alternative pathway for obtaining nutrients. We tested if the carnivorous pitcher plant Sarracenia purpurea could directly take up intact amino acids in the field and compared uptake of organic and inorganic forms of nitrogen across a gradient of nitrogen deposition. We hypothesized that the contribution of organic nitrogen to the nitrogen budget of the pitcher plant would decline with increasing nitrogen deposition. Methodology and Principal Findings At sites in Canada (low nitrogen deposition) and the United States (high nitrogen deposition), individual pitchers were fed two amino acids, glycine and phenylalanine, and inorganic nitrogen (as ammonium nitrate), individually and in mixture. Plants took up intact amino acids. Acquisition of each form of nitrogen provided in isolation exceeded uptake of the same form in mixture. At the high deposition site, uptake of organic nitrogen was higher than uptake of inorganic nitrogen. At the low deposition site, uptake of all three forms of nitrogen was similar. Completeness of the associated detritus-based food web that inhabits pitcher-plant leaves and breaks down captured prey had no effect on nitrogen uptake. Conclusions and Significance By taking up intact amino acids, Sarracenia purpurea can short-circuit the inorganic nitrogen cycle, thus minimizing potential bottlenecks in nitrogen availability that result from the plant's reliance for nitrogen mineralization on a seasonally reconstructed food web operating on infrequent and irregular prey capture. PMID:19582167

Characterizing Active Pharmaceutical Ingredient Binding to Human Serum Albumin by Spin-Labeling and EPR Spectroscopy.

PubMed

Hauenschild, Till; Reichenwallner, Jörg; Enkelmann, Volker; Hinderberger, Dariush

2016-08-26

Drug binding to human serum albumin (HSA) has been characterized by a spin-labeling and continuous-wave (CW) EPR spectroscopic approach. Specifically, the contribution of functional groups (FGs) in a compound on its albumin-binding capabilities is quantitatively described. Molecules from different drug classes are labeled with EPR-active nitroxide radicals (spin-labeled pharmaceuticals (SLPs)) and in a screening approach CW-EPR spectroscopy is used to investigate HSA binding under physiological conditions and at varying ratios of SLP to protein. Spectral simulations of the CW-EPR spectra allow extraction of association constants (KA ) and the maximum number (n) of binding sites per protein. By comparison of data from 23 SLPs, the mechanisms of drug-protein association and the impact of chemical modifications at individual positions on drug uptake can be rationalized. Furthermore, new drug modifications with predictable protein binding tendency may be envisaged. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Uptake of gentamicin by separated, viable renal tubules from rabbits.

PubMed

Barza, M; Murray, T; Hamburger, R J

1980-04-01

The proximal renal tubules have a marked affinity for gentamicin; they also are the major site of nephrotoxicity caused by this drug. The uptake of radiolabeled gentamicin in separated, viable renal tubules prepared by enzymatic digestion of rabbit kidneys was studied. The preparations showed rapid initial uptake of gentamicin followed by continued slower uptake. Accumulation was not affected by pH, but was significantly inhibited by ouabain, dinitrophenol, anoxia, and hypothermia in the absence of evident cellular damage. At gentamicin concentrations of greater than 50 microgram/ml in the medium, there was competition for drug uptake. Gentamicin efflux in tubules that were taken from a medium containing antibiotic and placed into antibiotic-free fluid was slow and incomplete. From these data it appears that gentamicin uptake by separated renal tubules occurs by a process that requires metabolic energy; thereafter, the drug resides in a poorly exchangeable cellular pool.

Contribution of electrostatics to the binding of pancreatic-type ribonucleases to membranes.

PubMed

Sundlass, Nadia K; Eller, Chelcie H; Cui, Qiang; Raines, Ronald T

2013-09-17

Pancreatic-type ribonucleases show clinical promise as chemotherapeutic agents but are limited in efficacy by the inefficiency of their uptake by human cells. Cellular uptake can be increased by the addition of positive charges to the surface of ribonucleases, either by site-directed mutagenesis or by chemical modification. This observation has led to the hypothesis that ribonuclease uptake by cells depends on electrostatics. Here, we use a combination of experimental and computational methods to ascertain the contribution of electrostatics to the cellular uptake of ribonucleases. We focus on three homologous ribonucleases: Onconase (frog), ribonuclease A (cow), and ribonuclease 1 (human). Our results support the hypothesis that electrostatics are necessary for the cellular uptake of Onconase. In contrast, specific interactions with cell-surface components likely contribute more to the cellular uptake of ribonuclease A and ribonuclease 1 than do electrostatics. These findings provide insight for the design of new cytotoxic ribonucleases.

Supporting the Uptake of Nursing Guidelines: what you really need to know to move nursing guidelines into practice.

PubMed

Matthew-Maich, Nancy; Ploeg, Jenny; Dobbins, Maureen; Jack, Susan

2013-05-01

There is a current push to use best practice guidelines (BPGs) in health care to enhance client care and outcomes. Even though intensive resources have been invested internationally to develop BPGs, a gap in knowledge exists about how to consistently and efficiently move them into practice. Constructivist grounded theory was used to explore the complex processes of a breastfeeding BPG implementation and uptake in three acute care hospitals. Interviews (n = 120) with 112 participants representing clients, nurses, lactation consultants, midwives, physicians, managers, administrators, and nurse educators as well as document and field note analysis informed this study. Data were analyzed using constant comparison and coding steps outlined by Charmaz: initial coding, selective (focused) coding, then theoretical coding. Triangulation of data types and sources were used as well as theoretical sampling. Data were collected from 2009 to 2010. Two sites showed BPG uptake while one did not. Factors present in the uptake sites included, ongoing passionate frontline leaders, the use of multifaceted strategies, and processes that occurred at organizational, leadership, individual and social levels. Particularly noteworthy was the transformation of individual nurses to believing in and using the BPG. Impacts occurred at client, nurse, unit, inter-professional, organizational and system levels. A conceptual framework: Supporting the Uptake of Nursing Guidelines, was developed that reveals essential processes used to facilitate BPG uptake into nursing practice and a process of nurse transformation to believing in and using the BPG. © Sigma Theta Tau International.

Uptake of antibiotics by human polymorphonuclear leukocyte cytoplasts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hand, W.L.; King-Thompson, N.L.

Enucleated human polymorphonuclear leukocytes (PMN cytoplasts), which have no nuclei and only a few granules, retain many of the functions of intact neutrophils. To better define the mechanisms and intracellular sites of antimicrobial agent accumulation in human neutrophils, we studied the antibiotic uptake process in PMN cytoplasts. Entry of eight radiolabeled antibiotics into PMN cytoplasts was determined by means of a velocity gradient centrifugation technique. Uptakes of these antibiotics by cytoplasts were compared with our findings in intact PMN. Penicillin entered both intact PMN and cytoplasts poorly. Metronidazole achieved a concentration in cytoplasts (and PMN) equal to or somewhat lessmore » than the extracellular concentration. Chloramphenicol, a lipid-soluble drug, and trimethoprim were concentrated three- to fourfold by cytoplasts. An unusual finding was that trimethroprim, unlike other tested antibiotics, was accumulated by cytoplasts more readily at 25 degrees C than at 37 degrees C. After an initial rapid association with cytoplasts, cell-associated imipenem declined progressively with time. Clindamycin and two macrolide antibiotics (roxithromycin, erythromycin) were concentrated 7- to 14-fold by cytoplasts. This indicates that cytoplasmic granules are not essential for accumulation of these drugs. Adenosine inhibited cytoplast uptake of clindamycin, which enters intact phagocytic cells by the membrane nucleoside transport system. Roxithromycin uptake by cytoplasts was inhibited by phagocytosis, which may reduce the number of cell membrane sites available for the transport of macrolides. These studies have added to our understanding of uptake mechanisms for antibiotics which are highly concentrated in phagocytes.« less

Characterization of the binding of 8-anilinonaphthalene sulphonate to rat class Mu GST M1-1

PubMed Central

Kinsley, Nichole; Sayed, Yasien; Armstrong, Richard N.; Dirr, Heini W.

2008-01-01

Molecular docking and ANS-displacement experiments indicated that 8-anilinonaphthalene sulphonate (ANS) binds the hydrophobic site (H-site) in the active site of dimeric class Mu rGST M1-1. The naphthalene moiety provides most of the van der Waals contacts at the ANS-binding interface while the anilino group is able to sample different rotamers. The energetics of ANS binding were studied by isothermal titration calorimetry (ITC) over the temperature range of 5–30 °C. Binding is both enthalpically and entropically driven and displays a stoichiometry of one ANS molecule per subunit (or H-site). ANS binding is linked to the uptake of 0.5 protons at pH 6.5. Enthalpy of binding depends linearly upon temperature yielding a ΔCp of −80 ± 4 cal K−1 mol−1 indicating the burial of solvent-exposed nonpolar surface area upon ANS-protein complex formation. While ion-pair interactions between the sulfonate moiety of ANS and protein cationic groups may be significant for other ANS-binding proteins, the binding of ANS to rGST M1-1 is primarily hydrophobic in origin. The binding properties are compared with those of other GSTs and ANS-binding proteins. PMID:18703268

Aspartic acid 397 in subunit B of the Na+-pumping NADH:quinone oxidoreductase from Vibrio cholerae forms part of a sodium-binding site, is involved in cation selectivity, and affects cation-binding site cooperativity.

PubMed

Shea, Michael E; Juárez, Oscar; Cho, Jonathan; Barquera, Blanca

2013-10-25

The Na(+)-pumping NADH:quinone complex is found in Vibrio cholerae and other marine and pathogenic bacteria. NADH:ubiquinone oxidoreductase oxidizes NADH and reduces ubiquinone, using the free energy released by this reaction to pump sodium ions across the cell membrane. In a previous report, a conserved aspartic acid residue in the NqrB subunit at position 397, located in the cytosolic face of this protein, was proposed to be involved in the capture of sodium. Here, we studied the role of this residue through the characterization of mutant enzymes in which this aspartic acid was substituted by other residues that change charge and size, such as arginine, serine, lysine, glutamic acid, and cysteine. Our results indicate that NqrB-Asp-397 forms part of one of the at least two sodium-binding sites and that both size and charge at this position are critical for the function of the enzyme. Moreover, we demonstrate that this residue is involved in cation selectivity, has a critical role in the communication between sodium-binding sites, by promoting cooperativity, and controls the electron transfer step involved in sodium uptake (2Fe-2S → FMNC).

Aspartic Acid 397 in Subunit B of the Na+-pumping NADH:Quinone Oxidoreductase from Vibrio cholerae Forms Part of a Sodium-binding Site, Is Involved in Cation Selectivity, and Affects Cation-binding Site Cooperativity

PubMed Central

Shea, Michael E.; Juárez, Oscar; Cho, Jonathan; Barquera, Blanca

2013-01-01

The Na+-pumping NADH:quinone complex is found in Vibrio cholerae and other marine and pathogenic bacteria. NADH:ubiquinone oxidoreductase oxidizes NADH and reduces ubiquinone, using the free energy released by this reaction to pump sodium ions across the cell membrane. In a previous report, a conserved aspartic acid residue in the NqrB subunit at position 397, located in the cytosolic face of this protein, was proposed to be involved in the capture of sodium. Here, we studied the role of this residue through the characterization of mutant enzymes in which this aspartic acid was substituted by other residues that change charge and size, such as arginine, serine, lysine, glutamic acid, and cysteine. Our results indicate that NqrB-Asp-397 forms part of one of the at least two sodium-binding sites and that both size and charge at this position are critical for the function of the enzyme. Moreover, we demonstrate that this residue is involved in cation selectivity, has a critical role in the communication between sodium-binding sites, by promoting cooperativity, and controls the electron transfer step involved in sodium uptake (2Fe-2S → FMNC). PMID:24030824

Phytoplankton productivity, respiration, and nutrient uptake and regeneration in the Potomac River, August 1977 - August 1978

USGS Publications Warehouse

Cole, B.E.; Harmon, D.D.

1981-01-01

Rates of phytoplankton productivity, respiration, and nutrient uptake and regeneration are presented. These observations were made on the Potomac River estuary (POTE) during four cruises between August 1977 and August 1978. Four experimental methods were used: carbon uptake using carbon-14, carbon uptake and respiration by a pH method, productivity and respiration by the dissolved oxygen method, and nutrient (NH4+, NO3-, NO2-, PO4=, and SiO2=) uptake and regeneration by colorimetry. The experiments were made at sites representative of conditions in four principal reaches of the tidal Potomac River estuary: near the mouth, seaward of the summer nutrient and phytoplankton maximum, near the region of maximum phytoplankton standing stock , and near the maximum anthropogenic nutrient source. (USGS)

Caffeine inhibition of GLUT1 is dependent on the activation state of the transporter.

PubMed

Gunnink, Leesha K; Busscher, Brianna M; Wodarek, Jeremy A; Rosette, Kylee A; Strohbehn, Lauren E; Looyenga, Brendan D; Louters, Larry L

2017-06-01

Caffeine has been shown to be a robust uncompetitive inhibitor of glucose uptake in erythrocytes. It preferentially binds to the nucleotide-binding site on GLUT1 in its tetrameric form and mimics the inhibitory action of ATP. Here we demonstrate that caffeine is also a dose-dependent, uncompetitive inhibitor of 2-deoxyglucose (2DG) uptake in L929 fibroblasts. The inhibitory effect on 2DG uptake in these cells was reversible with a rapid onset and was additive to the competitive inhibitory effects of glucose itself, confirming that caffeine does not interfere with glucose binding. We also report for the first time that caffeine inhibition was additive to inhibition by curcumin, suggesting distinct binding sites for curcumin and caffeine. In contrast, caffeine inhibition was not additive to that of cytochalasin B, consistent with previous data that reported that these two inhibitors have overlapping binding sites. More importantly, we show that the magnitude of maximal caffeine inhibition in L929 cells is much lower than in erythrocytes (35% compared to 90%). Two epithelial cell lines, HCLE and HK2, have both higher concentrations of GLUT1 and increased basal 2DG uptake (3-4 fold) compared to L929 cells, and subsequently display greater maximal inhibition by caffeine (66-70%). Interestingly, activation of 2DG uptake (3-fold) in L929 cells by glucose deprivation shifted the responsiveness of these cells to caffeine inhibition (35%-70%) without a change in total GLUT1 concentration. These data indicate that the inhibition of caffeine is dependent on the activity state of GLUT1, not merely on the concentration. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

Distribution and dynamics of nitrogen and microbial plankton in southern Lake Michigan during spring transition 1999-2000

NASA Astrophysics Data System (ADS)

Gardner, Wayne S.; Lavrentyev, Peter J.; Cavaletto, Joann F.; McCarthy, Mark J.; Eadie, Brian J.; Johengen, Thomas H.; Cotner, James B.

2004-03-01

Ammonium and amino acid fluxes were examined as indicators of N and microbial food web dynamics in southern Lake Michigan during spring. Either 15NH4+ or a mixture of 15N-labelled amino acids (both at 4 μM N final concentration) was added to Lake Michigan water. Net fluxes were measured over 24 h under natural light and dark conditions using deck-top incubators and compared to microbial food web characteristics. Isotope dilution experiments showed similar light and dark NH4+ regeneration rates at lake (6 versus 5 nM N h-1) and river-influenced (20 versus 24 nM N h-1) sites. Ammonium uptake rates were similar to regeneration rates in dark bottles. Dark uptake (attributed mainly to bacteria) accounted for ˜70% of total uptake (bacteria plus phytoplankton) in the light at most lake sites but only ˜30% of total uptake at river-influenced sites in or near the St. Joseph River mouth (SJRM). Cluster analysis grouped stations having zero, average, or higher than average N-cycling rates. Discriminant analysis indicated that chlorophyll concentration, oligotrich ciliate biomass, and total P concentration could explain 66% of N-cycling rate variation on average. Heterotrophic bacterial N demand was about one third of the NH4+ regeneration rate. Results suggest that, with the exception of SJRM stations, bacterial uptake and protist grazing mediated much of the N dynamics during spring transition. Since NH4+ is more available to bacteria than NO3-, regenerated NH4+ may have a strong influence on spring, lake biochemical energetics by enhancing N-poor organic matter degradation in this NO3- -replete ecosystem.

Prospective flutemetamol positron emission tomography and histopathology in normal pressure hydrocephalus.

PubMed

Rinne, Juha O; Frantzen, Janek; Leinonen, Ville; Lonnrot, Kimmo; Laakso, Aki; Virtanen, Kirsi A; Solin, Olof; Kotkansalo, Anna; Koivisto, Anne; Sajanti, Juha; Karppinen, Atte; Lehto, Hanna; Rummukainen, Jaana; Buckley, Chris; Smith, Adrian; Jones, Paul A; Sherwin, Paul; Farrar, Gill; McLain, Richard; Kailajarvi, Marita; Grachev, Igor D

2014-01-01

BACKGOUND/OBJECTIVE: To determine the level of association between uptake of the amyloid positron emission tomography (PET) imaging agent [(18)F]flutemetamol and the level of amyloid-β measured by immunohistochemical and histochemical staining in a frontal cortical region biopsy site. Seventeen patients with probable normal pressure hydrocephalus (NPH) underwent prospective [(18)F]flutemetamol PET and subsequent frontal cortical brain biopsy during ventriculoperitoneal shunting. Tissue amyloid-β was evaluated using the monoclonal antibody 4G8, thioflavin S and Bielschowsky silver stain. Four of the 17 patients (23.5%) had amyloid-β pathology based on the overall pathology read and also showed increased [(18)F]flutemetamol uptake. [(18)F]Flutemetamol standardized uptake values from the biopsy site were significantly associated with biopsy specimen amyloid-β levels (Pearson's r = 0.67; p = 0.006). There was also good correlation between the biopsy specimen amyloid-β level and uptake of [(18)F]flutemetamol in the region contralateral to the biopsy site (r = 0.67; p = 0.006), as well as with composite cortical [(18)F]flutemetamol uptake (r = 0.65; p = 0.008). The blinded visual read showed a high level of agreement between all readers (κ = 0.88). Two of 3 readers were in full agreement on all images; 1 reader disagreed on 1 of the 17 NPH cases. Blinded visual assessments of PET images by 1 reader were associated with 100% sensitivity to the overall pathology read, and assessments by the 2 others were associated with 75% sensitivity (overall sensitivity by majority read was 75%); specificity of all readers was 100%. [(18)F]Flutemetamol detects brain amyloid-β in vivo and shows promise as a valuable tool to study and possibly facilitate diagnosis of Alzheimer's disease both in patients with suspected NPH and among the wider population.

Comparison of radionuclide levels in soil, sagebrush, plant litter, cryptogams, and small mammals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landeen, D.S.

1994-09-01

Soil, sagebrush, plant litter, cryptogam, and small mammal samples were collected and analyzed for cesium-137, strontium-90, plutonium-238, plutonium 239/240, technetium-99, and iodine-129 from 1981 to 1986 at the US Department of Energy Hanford Site in southeastern Washington State as part of site characterization and environmental monitoring activities. Samples were collected on the 200 Areas Plateau, downwind from ongoing waste management activities. Plant litter, cryptogams, and small mammals are media that are not routinely utilized in monitoring or characterization efforts for determination of radionuclide concentrations. Studies at Hanford, other US Department of Energy sites, and in eastern Europe have indicated thatmore » plant litter and cryptogams may serve as effective ``natural`` monitors of air quality. Plant litter in this study consists of fallen leaves from sagebrush and ``cryptogams`` describes that portion of the soil crust composed of mosses, lichens, algae, and fungi. Comparisons of cesium-137 and strontium-90 concentrations in the soil, sagebrush, litter, and cryptogams revealed significantly higher (p<0.05) levels in plant litter and cryptogams. Technetium-99 values were the highest in sagebrush and litter. Plutonium-238 and 239/40 and iodine-129 concentrations never exceeded 0.8 pCi/gm in all media. No evidence of any significant amounts of any radionuclides being incorporated into the small mammal community was discovered. The data indicate that plant litter and cryptogams may be better, indicators of environmental quality than soil or vegetation samples. Augmenting a monitoring program with samples of litter and cryptogams may provide a more accurate representation of radionuclide environmental uptake and/or contamination levels in surrounding ecosystems. The results of this study may be applied directly to other radioecological monitoring conducted at other nuclear sites and to the monitoring of other pollutants.« less

Salmonella typhimurium IroN and FepA Proteins Mediate Uptake of Enterobactin but Differ in Their Specificity for Other Siderophores

PubMed Central

Rabsch, Wolfgang; Voigt, Wolfgang; Reissbrodt, Rolf; Tsolis, Renée M.; Bäumler, Andreas J.

1999-01-01

Salmonella typhimurium possesses two outer membrane receptor proteins, IroN and FepA, which have been implicated in the uptake of enterobactin. To determine whether both receptors have identical substrate specificities, fepA and iroN mutants and a double mutant were characterized. While both receptors transported enterobactin, the uptake of corynebactin and myxochelin C was selectively mediated by IroN and FepA, respectively. PMID:10348879

Characterization of loxoprofen transport in Caco-2 cells: the involvement of a proton-dependent transport system in the intestinal transport of loxoprofen.

PubMed

Narumi, Katsuya; Kobayashi, Masaki; Kondo, Ayuko; Furugen, Ayako; Yamada, Takehiro; Takahashi, Natsuko; Iseki, Ken

2016-11-01

Loxoprofen, a propionate non-steroidal anti-inflammatory drug (NSAID), is used widely in East Asian countries. However, little is known about the transport mechanisms contributing to its intestinal absorption. The objectives of this study were to characterize the intestinal transport of loxoprofen using the human intestinal Caco-2 cell model. The transport of loxoprofen was investigated in cellular uptake studies. The uptake of loxoprofen into Caco-2 cells was pH- and concentration-dependent, and was described by a Michaelis-Menten equation with passive diffusion (K m : 4.8 mm, V max : 142 nmol/mg protein/30 s, and K d : 2.2 μl/mg protein/30 s). Moreover, the uptake of loxoprofen was inhibited by a typical monocarboxylate transporter (MCT) inhibitor as well as by various monocarboxylates. The uptake of [ 14 C] l-lactic acid, a typical MCT substrate, in Caco-2 cells was saturable with relatively high affinity for MCT. Because loxoprofen inhibited the uptake of [ 14 C] l-lactic acid in a noncompetitive manner, it was unlikely that loxoprofen uptake was mediated by high-affinity MCT(s). Our results suggest that transport of loxoprofen in Caco-2 cells is, at least in part, mediated by a proton-dependent transport system. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Fluorescence-encoded gold nanoparticles: library design and modulation of cellular uptake into dendritic cells.

PubMed

Rodriguez-Lorenzo, Laura; Fytianos, Kleanthis; Blank, Fabian; von Garnier, Christophe; Rothen-Rutishauser, Barbara; Petri-Fink, Alke

2014-04-09

In order to harness the unique properties of nanoparticles for novel clinical applications and to modulate their uptake into specific immune cells we designed a new library of homo- and hetero-functional fluorescence-encoded gold nanoparticles (Au-NPs) using different poly(vinyl alcohol) and poly(ethylene glycol)-based polymers for particle coating and stabilization. The encoded particles were fully characterized by UV-Vis and fluorescence spectroscopy, zeta potential and dynamic light scattering. The uptake by human monocyte derived dendritic cells in vitro was studied by confocal laser scanning microscopy and quantified by fluorescence-activated cell sorting and inductively coupled plasma atomic emission spectroscopy. We show how the chemical modification of particle surfaces, for instance by attaching fluorescent dyes, can conceal fundamental particle properties and modulate cellular uptake. In order to mask the influence of fluorescent dyes on cellular uptake while still exploiting its fluorescence for detection, we have created hetero-functionalized Au-NPs, which again show typical particle dependent cellular interactions. Our study clearly prove that the thorough characterization of nanoparticles at each modification step in the engineering process is absolutely essential and that it can be necessary to make substantial adjustments of the particles in order to obtain reliable cellular uptake data, which truly reflects particle properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controls on seasonal patterns of maximum ecosystem carbon uptake and canopy-scale photosynthetic light response: contributions from both temperature and photoperiod.

PubMed

Stoy, Paul C; Trowbridge, Amy M; Bauerle, William L

2014-02-01

Most models of photosynthetic activity assume that temperature is the dominant control over physiological processes. Recent studies have found, however, that photoperiod is a better descriptor than temperature of the seasonal variability of photosynthetic physiology at the leaf scale. Incorporating photoperiodic control into global models consequently improves their representation of the seasonality and magnitude of atmospheric CO2 concentration. The role of photoperiod versus that of temperature in controlling the seasonal variability of photosynthetic function at the canopy scale remains unexplored. We quantified the seasonal variability of ecosystem-level light response curves using nearly 400 site years of eddy covariance data from over eighty Free Fair-Use sites in the FLUXNET database. Model parameters describing maximum canopy CO2 uptake and the initial slope of the light response curve peaked after peak temperature in about 2/3 of site years examined, emphasizing the important role of temperature in controlling seasonal photosynthetic function. Akaike's Information Criterion analyses indicated that photoperiod should be included in models of seasonal parameter variability in over 90% of the site years investigated here, demonstrating that photoperiod also plays an important role in controlling seasonal photosynthetic function. We also performed a Granger causality analysis on both gross ecosystem productivity (GEP) and GEP normalized by photosynthetic photon flux density (GEP n ). While photoperiod Granger-caused GEP and GEP n in 99 and 92% of all site years, respectively, air temperature Granger-caused GEP in a mere 32% of site years but Granger-caused GEP n in 81% of all site years. Results demonstrate that incorporating photoperiod may be a logical step toward improving models of ecosystem carbon uptake, but not at the expense of including enzyme kinetic-based temperature constraints on canopy-scale photosynthesis.

The Potential of Carbonyl Sulfide as a Tracer for Gross Primary Productivity at Flux Tower Sites

USDA-ARS?s Scientific Manuscript database

Regional/continental scale studies of atmospheric carbonyl sulfide (OCS) seasonal dynamics and leaf level studies of plant OCS uptake have shown a close relationship to CO2 dynamics and uptake, suggesting potential for OCS as a tracer for gross primary productivity (GPP). Canopy CO2 and OCS differen...

Uptake of As, Cd, Cu, Fe, Mn, Pb, and Zn in pasture grasses on three metal-contamimated soils from Montana

USDA-ARS?s Scientific Manuscript database

One of the biggest challenges to successfully phytoremediate contaminated mine land soils is the identification of plant materials that possess a broad adaptation to ecological sites and either exclude or uptake heavy metals of interest. This study evaluted forage concentrations (mg kg-1 DM) of arse...

Non-Invasive Methods to Characterize Soil-Plant Interactions at Different Scales

NASA Astrophysics Data System (ADS)

Javaux, M.; Kemna, A.; Muench, M.; Oberdoerster, C.; Pohlmeier, A.; Vanderborght, J.; Vereecken, H.

2006-05-01

Root water uptake is a dynamic and non-linear process, which interacts with the soil natural variability and boundary conditions to generate heterogeneous spatial distributions of soil water. Soil-root fluxes are spatially variable due to heterogeneous gradients and hydraulic connections between soil and roots. While 1-D effective representation of the root water uptake has been successfully applied to predict transpiration and average water content profiles, finer spatial characterization of the water distribution may be needed when dealing with solute transport. Indeed, root water uptake affects the water velocity field, which has an effect on solute velocity and dispersion. Although this variability originates from small-scale processes, these may still play an important role at larger scales. Therefore, in addition to investigate the variability of the soil hydraulic properties, experimental and numerical tools for characterizing root water uptake (and its effects on soil water distribution) from the pore to the field scales are needed to predict in a proper way the solute transport. Obviously, non-invasive and modeling techniques which are helpful to achieve this objective will evolve with the scale of interest. At the pore scale, soil structure and root-soil interface phenomena have to be investigated to understand the interactions between soil and roots. Magnetic resonance imaging may help to monitor water gradients and water content changes around roots while spectral induced polarization techniques may be used to characterize the structure of the pore space. At the column scale, complete root architecture of small plants and water content depletion around roots can be imaged by magnetic resonance. At that scale, models should explicitly take into account the three-dimensional gradient dependency of the root water uptake, to be able to predict solute transport. At larger scales however, simplified models, which implicitly take into account the heterogeneous root water uptake along roots, should be preferred given the complexity of the system. At such scales, electrical resistance tomography or ground-penetrating radar can be used to map the water content changes and derive effective parameters for predicting solute transport.

18F-FDG PET/CT in Diagnostic and Prognostic Evaluation of Patients With Suspected Recurrence of Chondrosarcoma.

PubMed

Vadi, Shelvin Kumar; Mittal, Bhagwant Rai; Gorla, Arun Kumar Reddy; Sood, Ashwani; Basher, Rajender Kumar; Sood, Apurva; Kakkar, Nandita; Sen, Ramesh K

2018-02-01

The aim of the study was to analyze the diagnostic and prognostic utility of F-FDG PET/CT to predict the disease-specific survival (DSS) with FDG uptake and tumor grade in recurrent chondrosarcoma. Retrospective analysis of FDG PET/CT findings in 31 previously treated patients (46 studies) with mean follow-up period of 40.7 ± 23.9 months (range, 3-77 months) from the date of first PET/CT study was done. Kaplan-Meier DSS analysis was made with respect to tumor grade, FDG uptake at the recurrent primary sites, and a combination of grade and FDG uptake as parameters. Recurrence (local and distant) was shown in 28 (60.8%) of 46 FDG PET/CT studies with sensitivity and specificity of 88.9% and 78.9%, respectively. The median SUVmax at the recurrent primary sites differed significantly (P = 0.008) among 3 tumor grade groups, with higher median SUVmax in higher grades. There was significant difference in median SUVmax among different grade groups except between grade II and grade III. Recurrent primary site SUVmax cutoff at 6.15 derived from the receiver operating characteristic curve yielded significant difference (P < 0.001) in mean DSS time. Significant difference in survival was noted between 3 different tumor grade groups (P = 0.016). The combination of SUVmax and grade improved the survival prediction than with grade alone. In recurrent chondrosarcoma, the recurrent primary site FDG uptake and grade were found to be reliable prognostic factors with respect to DSS. PET/CT in recurrence setting has the potential to predict tumor grade and survival and may assist in clinical management.

Repeatability of quantitative FDG-PET/CT and contrast-enhanced CT in recurrent ovarian carcinoma: test-retest measurements for tumor FDG uptake, diameter, and volume.

PubMed

Rockall, Andrea G; Avril, Norbert; Lam, Raymond; Iannone, Robert; Mozley, P David; Parkinson, Christine; Bergstrom, Donald; Sala, Evis; Sarker, Shah-Jalal; McNeish, Iain A; Brenton, James D

2014-05-15

Repeatability of baseline FDG-PET/CT measurements has not been tested in ovarian cancer. This dual-center, prospective study assessed variation in tumor 2[18F]fluoro-2-deoxy-D-glucose (FDG) uptake, tumor diameter, and tumor volume from sequential FDG-PET/CT and contrast-enhanced computed tomography (CECT) in patients with recurrent platinum-sensitive ovarian cancer. Patients underwent two pretreatment baseline FDG-PET/CT (n = 21) and CECT (n = 20) at two clinical sites with different PET/CT instruments. Patients were included if they had at least one target lesion in the abdomen with a standardized uptake value (SUV) maximum (SUVmax) of ≥ 2.5 and a long axis diameter of ≥ 15 mm. Two independent reading methods were used to evaluate repeatability of tumor diameter and SUV uptake: on site and at an imaging clinical research organization (CRO). Tumor volume reads were only performed by CRO. In each reading set, target lesions were independently measured on sequential imaging. Median time between FDG-PET/CT was two days (range 1-7). For site reads, concordance correlation coefficients (CCC) for SUVmean, SUVmax, and tumor diameter were 0.95, 0.94, and 0.99, respectively. Repeatability coefficients were 16.3%, 17.3%, and 8.8% for SUVmean, SUVmax, and tumor diameter, respectively. Similar results were observed for CRO reads. Tumor volume CCC was 0.99 with a repeatability coefficient of 28.1%. There was excellent test-retest repeatability for FDG-PET/CT quantitative measurements across two sites and two independent reading methods. Cutoff values for determining change in SUVmean, SUVmax, and tumor volume establish limits to determine metabolic and/or volumetric response to treatment in platinum-sensitive relapsed ovarian cancer. ©2014 American Association for Cancer Research.

Natural attenuation of metals and radionuclides: Report from a workshop held by Sandia National Laboratories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brady, P.V.; Borns, D.J.

1997-11-01

Natural attenuation is increasingly applied to remediate contaminated soils and ground waters. Roughly 25% of Superfund groundwater remedies in 1995 involved some type of monitored natural attenuation, compared to almost none 5 years ago. Remediation by natural attenuation (RNA) requires clear evidence that contaminant levels are decreasing sufficiently over time, a defensible explanation of the attenuation mechanism, long-term monitoring, and a contingency plan at the very least. Although the primary focus of implementation has to date been the biodegradation of organic contaminants, there is a wealth of scientific evidence that natural processes reduce the bioavailability of contaminant metals and radionuclides.more » Natural attenuation of metals and radionuclides is likely to revolve around sorption, solubility, biologic uptake and dilution controls over contaminant availability. Some of these processes can be applied to actively remediate sites. Others, such as phytoremediation, are likely to be ineffective. RNA of metals and radionuclides is likely to require specialized site characterization to construct contaminant and site-specific conceptual models of contaminant behavior. Ideally, conceptual models should be refined such that contaminant attenuation can be confidently predicted into the future. The technical approach to RNA of metals and radionuclides is explored here.« less

Distribution of 3H-GABA uptake sites in the nematode Ascaris

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guastella, J.; Stretton, A.O.

1991-05-22

The distribution of uptake sites for the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the nematode Ascaris suum was examined by autoradiography of 3H-GABA uptake. Single neural processes in both the ventral and dorsal nerve cords were labeled with 3H-GABA. Serial section analysis identified the cells of origin of these processes as the RMEV-like and RMED-like neurons. These cells belong to a set of four neurons in the nerve ring, all of which are labeled by 3H-GABA. 3H-GABA labeling of at least two other sets of cephalic neurons was seen. One of these pairs consists of medium-sized lateral ganglia neurons, locatedmore » at the level of the amphid commissure bundle. A second pair is located in the lateral ganglia at the level of the deirid commissure bundle. The position and size of these lateral ganglia cells suggest that they are the GABA-immunoreactive lateral ganglia cells frequently seen in whole-mount immunocytochemical preparations. Four neuronal cell bodies located in the retrovesicular ganglion were also labeled with 3H-GABA. These cells, which are probably cholinergic excitatory motor neurons, do not contain detectable GABA-like immunoreactivity. Heavy labeling of muscle cells was also observed. The ventral and dorsal nerve cord inhibitory motor neurons, which are known to contain GABA-like immunoreactivity, were not labeled above background with 3H-GABA. Together with the experiments reported previously, these results define three classes of GABA-associated neurons in Ascaris: (1) neurons that contain endogenous GABA and possess a GABA uptake system; (2) neurons that contain endogenous GABA, but that either lack a GABA uptake system or possess a GABA uptake system of low activity; (3) neurons that possess a GABA uptake system, but that lack endogenous GABA.« less

Bounding the heterogeneous gas uptake on aerosols and ground using resistance model

NASA Astrophysics Data System (ADS)

Su, H.; Li, M.; Cheng, Y.

2017-12-01

Heterogeneous uptake on aerosols and ground are potential important atmospheric sinks for gases. Different schemes have been used to characterize the dry deposition and heterogeneous aerosol gas uptake, although they share similar characteristics. In this work, we propose a unified resistance model to compare the uptake flux on both ground and aerosols, to identify the dominate heterogeneous process within the planetary boundary layer (PBL). The Gamma(eq) is introduced to represent the reactive uptake coefficient on aerosols when these two processes are equally important. It's shown that Gamma(eq) is proportional to the dry deposition velocity, inversely proportional to aerosol surface area concentration. Under typical regional background condition, Gamma(eq) vary from 1x10-5 to 4x10-4 with gas species, land-use type and season, which indicates that aerosol gas uptake should be included in atmospheric models when uptake coefficient higher than 10-5. We address the importance of heterogeneous gas uptake on aerosols over ground especially for ozone uptake on liquid organic aerosols and for marine PBL atmosphere.

[Methoxyflurane and ethanol do not inhibit the neuronal uptake of noradrenaline (uptake 1) at the desipramine binding site].

PubMed

Kress, H G; Schömig, E

1990-07-01

We recently demonstrated that the net accumulation of 3H-norepinephrine in the rat pheochromocytoma cell line PC12 was reduced by anesthetic concentrations of n-alkanols and the volatile anesthetics halothane, enflurane, isoflurane, and methoxyflurane. In PC12 cells, as in adrenergic neurons, norepinephrine is transported across the plasma membrane by a saturable, high-affinity, carrier-mediated mechanism (uptake1), which follows Michaelis-Menten kinetics, is energy- and sodium-dependent, and is inhibited by low concentrations of cocaine and the tricyclic antidepressant desipramine. Although uptake1 is the most important process for the removal of norepinephrine from the synaptic cleft, the net accumulation of norepinephrine within the neuron also depends on other factors including its vesicular uptake and storage within the granules, its metabolism by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT), and the efflux of its more lipophilic metabolites. In our previous report we could not exclude the contribution of any of these factors to the observed inhibitory effects of volatile substances. Therefore, the aim of the present study with ethanol and methoxyflurane was: (1) to elucidate further the exact mechanism responsible for the reduction of the norepinephrine accumulation; and (2) to investigate the anesthetics' interaction with the substrate recognition site, which is identical with the desipramine binding site on the norepinephrine carrier. METHODS. For 3H-norepinephrine uptake experiments, PC12 cells were cultured on dishes (60 mm, Nunc) coated with polyornithine. Reserpine (10 microM) was added to the culture 24 h before the experiment to deplete endogenous norepinephrine. The initial carrier-mediated transport rate (60 s) was measured as previously described. 3H-desipramine equilibrium binding was determined with isolated plasma membranes prepared from PC12 cells grown in suspension culture. The carrier-mediated uptake of 3H-norepinephrine and the specific 3H-desipramine binding were defined as those inhibited by 1 microM nisoxetine. All buffers contained 10 microM pargyline and 10 microM U-0521 to inhibit MAO and COMT. Incubations were done in the presence and absence of methoxyflurane (1% and 2% vol/vol in synthetic air containing 5% CO2) or ethanol (5% vol/vol). Media had been equilibrated with methoxyflurane by bubbling (30 min) and were routinely checked by gas chromatography. RESULTS AND DISCUSSION. Methoxyflurane and ethanol inhibited uptake1. However, reduction of uptake1 was far less pronounced than that previously found for the net accumulation of norepinephrine. Even at a vaporous concentration of 2% (corresponding with an over 15-fold half-maximal inhibitory concentration for norepinephrine accumulation), methoxyflurane produced only 58% inhibition of the high-affinity uptake...

Ion Mobility Spectrometry-Hydrogen Deuterium Exchange Mass Spectrometry of Anions: Part 2. Assessing Charge Site Location and Isotope Scrambling

NASA Astrophysics Data System (ADS)

Khakinejad, Mahdiar; Ghassabi Kondalaji, Samaneh; Donohoe, Gregory C.; Valentine, Stephen J.

2016-03-01

Ion mobility spectrometry (IMS) coupled with gas-phase hydrogen deuterium exchange (HDX)-mass spectrometry (MS) and molecular dynamic simulations (MDS) has been used for structural investigation of anions produced by electrospraying a sample containing a synthetic peptide having the sequence KKDDDDDIIKIIK. In these experiments the potential of the analytical method for locating charge sites on ions as well as for utilizing collision-induced dissociation (CID) to reveal the degree of deuterium uptake within specific amino acid residues has been assessed. For diffuse (i.e., more elongated) [M - 2H]2- ions, decreased deuterium content along with MDS data suggest that the D4 and D6 residues are charge sites, whereas for the more diffuse [M - 3H]3- ions, the data suggest that the D4, D7, and the C-terminus are deprotonated. Fragmentation of mobility-selected, diffuse [M - 2H]2- ions to determine deuterium uptake at individual amino acid residues reveals a degree of deuterium retention at incorporation sites. Although the diffuse [M - 3H]3- ions may show more HD scrambling, it is not possible to clearly distinguish HD scrambling from the expected deuterium uptake based on a hydrogen accessibility model. The capability of the IMS-HDX-MS/MS approach to provide relevant details about ion structure is discussed. Additionally, the ability to extend the approach for locating protonation sites on positively-charged ions is presented.

Screening hydroxyapatite for cadmium and lead immobilization in aqueous solution and contaminated soil: The role of surface area.

PubMed

Li, Hongying; Guo, Xisheng; Ye, Xinxin

2017-02-01

Hydroxyapatite (HAP) has been widely used to immobilize many cationic metals in water and soils. The specific reason why an increase in the surface area of HAP enhances cadmium (Cd) uptake, but has no effect on lead (Pb) uptake, is not clear. The aim of this study was to determine the factors causing the differences in sorption behavior between Cd and Pb by evaluating HAPs with different surface areas. We synthesized HAPs with two different surface areas, which were characterized by X-ray diffraction, N 2 adsorption, and scanning electron microscopy, and then evaluated them as sorbents for Cd and Pb removal by testing in single and binary systems. The sorption capacity of large surface area HAP (1.85mmol/g) for Cd in the single-metal system was higher than that of small surface area HAP (0.64mmol/g), but there were no differences between single- and binary-metal solutions containing Pb. After the Cd experiments, the HAP retained a stable structure and intact morphology, which promotes the accessibility of reactive sites for Cd. However, a newly formed precipitate covered the surface and blocked the channels in the presence of Pb, which reduced the number of potential adsorption sites on HAP for Cd and Pb. Remediation experiments using Cd- and Pb-contaminated soil produced similar results to the solution tests. These results indicate that alterations of the structure and morphology during the reaction is an important factor influencing metal sorption to HAP. Copyright © 2016. Published by Elsevier B.V.

Impacts of manganese mining activity on the environment: interactions among soil, plants, and arbuscular mycorrhiza.

PubMed

Rivera-Becerril, Facundo; Juárez-Vázquez, Lucía V; Hernández-Cervantes, Saúl C; Acevedo-Sandoval, Otilio A; Vela-Correa, Gilberto; Cruz-Chávez, Enrique; Moreno-Espíndola, Iván P; Esquivel-Herrera, Alfonso; de León-González, Fernando

2013-02-01

The mining district of Molango in the Hidalgo State, Mexico, possesses one of the largest deposits of manganese (Mn) ore in the world. This research assessed the impacts of Mn mining activity on the environment, particularly the interactions among soil, plants, and arbuscular mycorrhiza (AM) at a location under the influence of an open Mn mine. Soils and plants from three sites (soil under maize, soil under native vegetation, and mine wastes with some vegetation) were analyzed. Available Mn in both soil types and mine wastes did not reach toxic levels. Samples of the two soil types were similar regarding physical, chemical, and biological properties; mine wastes were characterized by poor physical structure, nutrient deficiencies, and a decreased number of arbuscular mycorrhizal fungi (AMF) spores. Tissues of six plant species accumulated Mn at normal levels. AM was absent in the five plant species (Ambrosia psilostachya, Chenopodium ambrosoides, Cynodon dactylon, Polygonum hydropiperoides, and Wigandia urens) established in mine wastes, which was consistent with the significantly lower number of AMF spores compared with both soil types. A. psilostachya (native vegetation) and Zea mays showed mycorrhizal colonization in their root systems; in the former, AM significantly decreased Mn uptake. The following was concluded: (1) soils, mine wastes, and plant tissues did not accumulate Mn at toxic levels; (2) despite its poor physical structure and nutrient deficiencies, the mine waste site was colonized by at least five plant species; (3) plants growing in both soil types interacted with AMF; and (4) mycorrhizal colonization of A. psilostachya influenced low uptake of Mn by plant tissues.

Imaging vascular endothelial growth factor (VEGF) receptors in turpentine-induced sterile thigh abscesses with radiolabeled single-chain VEGF.

PubMed

Levashova, Zoia; Backer, Marina; Backer, Joseph M; Blankenberg, Francis G

2009-12-01

Angiogenesis plays a central role in the pathogenesis of chronic inflammatory disorders. Vascular endothelial growth factor (VEGF) and its receptors are the most important regulators of angiogenesis. We wished to determine whether labeled forms of single-chain VEGF (scVEGF) could be used to image VEGF receptors in a well-characterized model of sterile soft-tissue inflammation induced by intramuscular injection of turpentine. Anesthetized adult male Swiss-Webster mice received a 20-microL intramuscular injection of turpentine into the right thigh. At 4, 7, or 10 d later, groups of 3-5 mice were injected via the tail vein with 50 microg of either scVEGF that had been site specifically labeled with Cy5.5 (scVEGF/Cy) or inactivated scVEGF/Cy (inVEGF/Cy) and then examined by fluorescence imaging. At 3, 4, 6, 7, 9, 10, or 12 d, additional groups of 3-5 mice were injected via the tail vein with 74-111 MBq of (99m)Tc-scVEGF (or (99m)Tc-inVEGF) and then examined by SPECT imaging. On days 3 through 10, both forms of scVEGF (scVEGF/Cy and (99m)Tc-scVEGF) showed significantly higher uptake (P < 0.05) in the right (abscessed) thigh than in the contralateral thigh (and higher uptake than the inactivated tracer). Peak uptake occurred on day 7 (3.67 +/- 1.79 [ratio of uptake in abscessed thigh to uptake in normal thigh, mean +/- SD] and 0.72 +/- 0.01 for scVEGF/Cy and inVEGF/Cy, respectively, and 3.49 +/- 1.22 and 1.04 +/- 0.41 for (99m)Tc-scVEGF and (99m)Tc-inVEGF, respectively) and slowly decreased thereafter. Autoradiography revealed peak tracer uptake in the thick irregular angiogenic rim of the abscess cavity on day 9 (5.83 x 10(-7) +/- 9.22 x 10(-8) and 5.85 x 10(-8) +/- 5.95 x 10(-8) percentage injected dose per pixel for (99m)Tc-scVEGF and (99m)Tc-inVEGF, respectively); in comparison, a thin circumscribed rim of uptake was seen with (99m)Tc-inVEGF. Immunostaining revealed that VEGFR-2 (VEGF receptor) colocalized with CD31 (endothelial cell marker) at all time points in the abscess rim, whereas F4/80 (macrophage) immunostaining reached a maximum at day 7 and decreased by day 10. The uptake of scVEGF in turpentine-induced abscesses was specific and directly related to VEGFR-2 expression in the neovasculature of the angiogenic rim. Peak tracer uptake coincided with maximum macrophage infiltration, suggesting that scVEGF imaging may be useful for the detection, localization, and monitoring of chronic inflammation in bone, joints, or soft tissues.

Intracerebroventricular administration of okadaic acid induces hippocampal glucose uptake dysfunction and tau phosphorylation.

PubMed

Broetto, Núbia; Hansen, Fernanda; Brolese, Giovana; Batassini, Cristiane; Lirio, Franciane; Galland, Fabiana; Dos Santos, João Paulo Almeida; Dutra, Márcio Ferreira; Gonçalves, Carlos-Alberto

2016-06-01

Intraneuronal aggregates of neurofibrillary tangles (NFTs), together with beta-amyloid plaques and astrogliosis, are histological markers of Alzheimer's disease (AD). The underlying mechanism of sporadic AD remains poorly understood, but abnormal hyperphosphorylation of tau protein is suggested to have a role in NFTs genesis, which leads to neuronal dysfunction and death. Okadaic acid (OKA), a strong inhibitor of protein phosphatase 2A, has been used to induce dementia similar to AD in rats. We herein investigated the effect of intracerebroventricular (ICV) infusion of OKA (100 and 200ng) on hippocampal tau phosphorylation at Ser396, which is considered an important fibrillogenic tau protein site, and on glucose uptake, which is reduced early in AD. ICV infusion of OKA (at 200ng) induced a spatial cognitive deficit, hippocampal astrogliosis (based on GFAP increment) and increase in tau phosphorylation at site 396 in this model. Moreover, we observed a decreased glucose uptake in the hippocampal slices of OKA-treated rats. In vitro exposure of hippocampal slices to OKA altered tau phosphorylation at site 396, without any associated change in glucose uptake activity. Taken together, these findings further our understanding of OKA neurotoxicity, in vivo and vitro, particularly with regard to the role of tau phosphorylation, and reinforce the importance of the OKA dementia model for studying the neurochemical alterations that may occur in AD, such as NFTs and glucose hypometabolism. Copyright © 2016 Elsevier Inc. All rights reserved.

Convergence of the effect of root hydraulic functioning and root hydraulic redistribution on ecosystem water and carbon balance across divergent forest ecosystems

NASA Astrophysics Data System (ADS)

domec, J.; King, J. S.; Ogée, J.; Noormets, A.; Warren, J.; Meinzer, F. C.; Sun, G.; Jordan-Meille, L.; Martineau, E.; Brooks, R. J.; Laclau, J.; Battie Laclau, P.; McNulty, S.

2012-12-01

INVITED ABSTRACT: Deep root water uptake and hydraulic redistribution (HR) play a major role in forest ecosystems during drought, but little is known about the impact of climate change on root-zone processes influencing HR and its consequences on water and carbon fluxes. Using data from two old growth sites in the western USA, two mature sites in the eastern USA, one site in southern Brazil, and simulations with the process-based model MuSICA, our objectives were to show that HR can 1) mitigate the effects of soil drying on root functioning, and 2) have important implications for carbon uptake and net ecosystem exchange (NEE). In a dry, old-growth ponderosa pine (USA) and a eucalyptus stand (Brazil) both characterized by deep sandy soils, HR limited the decline in root hydraulic conductivity and increased dry season tree transpiration (T) by up to 30%, which impacted NEE through major increases in gross primary productivity (GPP). The presence of deep-rooted trees did not necessarily imply high rates of HR unless soil texture allowed large water potential gradients to occur, as was the case in the wet old-growth Douglas-fir/mixed conifer stand. At the Duke mixed hardwood forest characterized by a shallow clay-loam soil, modeled HR was low but not negligible, representing annually up to 10% of T, and maintaining root conductance high. At this site, in the absence of HR, it was predicted that annual GPP would have been diminished by 7-19%. At the coastal loblolly pine plantation, characterized by deep organic soil, HR limited the decline in shallow root conductivity by more than 50% and increased dry season T by up to 40%, which increased net carbon gain by the ecosystem by about 400 gC m-2 yr-1, demonstrating the significance of HR in maintaining the stomatal conductance and assimilation capacity of the whole ecosystem. Under future climate conditions (elevated atmospheric [CO2] and temperature), HR is predicted to be reduced by up to 50%; reducing the resilience of trees to droughts. Under future conditions, T is predicted to stay the same at the Duke mixed hardwood forest, but to decline slightly at the coastal loblolly pine plantation and slightly increase at the old-growth ponderosa pine stand and the eucalyptus plantation. As a consequence, water use efficiency in all sites was predicted to improve dramatically under future climate conditions. Our simulations also showed that the negative effect of drier nights on HR would be greater under future climate conditions. Assuming no increase in stomatal control with increasing drier nights, increased vapor pressure deficit at night under future conditions was sufficient to drive significant nighttime T at all sites , which reduced HR, because the plant and the atmosphere became a sink for hydraulically redistributed water . We concluded that the predicted reductions in HR under future climate conditions are expected to play an important regulatory role in land-atmosphere interactions by affecting whole ecosystem carbon and water balance. We suggest that root distribution should be treated dynamically in response to climate change and that HR and its interactions with rooting depth and soil texture should be implemented in soil-vegetation-atmosphere transfer models.

Up-scaling mineral-aqueous interfacial processes that govern isotope and trace element partitioning during calcite growth

NASA Astrophysics Data System (ADS)

Lammers, L. N.

2014-12-01

The dependence of the isotopic and trace element composition of calcium carbonate minerals on growth conditions including temperature, pH, and salinity is widely used to infer paleoclimate conditions. These inferences rely heavily on phenomenological observations of biogenic and inorganic precipitation both in and ex situ, where only limited variability in solution conditions can be explored. Ionic fluxes between the mineral surface and aqueous growth solution govern the net uptake of both stoichiometric and trace species during calcification, so developing a mechanistic understanding of the reactions governing these fluxes is critical to refine existing proxies and to develop new ones. The micro-scale mechanisms of calcite precipitation from aqueous solution have been extensively studied, and net ionic uptake post-nucleation is known to occur primarily at monomolecular kink sites along step edges at the mineral surface. In this talk, I will present a theoretical framework that uses the quasi-elementary ion attachment and detachment reactions governing ion uptake at kink sites to simultaneously model bulk mineral growth kinetics and tracer partitioning during calcite precipitation. Several distinct processes occur during ion uptake at kink sites that can influence the distribution of trace species, directly impacting the composition of various carbonate paleoproxies including δ44Ca, δ18O, Sr/Ca and Mg/Ca. The distribution of these trace species will be shown to depend on (1) the relative rates of ion desolvation during attachment to kink sites, (2) the relative rates of bond breaking during detachment from kink sites, and (3) the equilibrium partitioning of trace aqueous species. This model accounts for the impact of solution conditions on net ion fluxes and surface speciation, which in turn controls the population of kink sites available for direct ion exchange with the aqueous phase. The impacts of solution variables including pH, temperature and salinity can be treated independently, which unlike traditional partitioning studies allows the impacts of these parameters to be deconvolved. The type of theoretical framework discussed here can be readily extended to explicitly account for each of the major solution composition variables that are implicated in paleoproxy composition.

A field study on the dynamic uptake and transfer of heavy metals in Chinese cabbage and radish in weak alkaline soils.

PubMed

Ai, Shiwei; Guo, Rui; Liu, Bailin; Ren, Liang; Naeem, Sajid; Zhang, Wenya; Zhang, Yingmei

2016-10-01

Vegetables and crops can take up heavy metals when grown on polluted lands. The concentrations and dynamic uptake of heavy metals vary at different growth points for different vegetables. In order to assess the safe consumption of vegetables in weak alkaline farmlands, Chinese cabbage and radish were planted on the farmlands of Baiyin (polluted site) and Liujiaxia (relatively unpolluted site). Firstly, the growth processes of two vegetables were recorded. The growth curves of the two vegetables observed a slow growth at the beginning, an exponential growth period, and a plateau towards the end. Maximum concentrations of copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd) were presented at the slow growth period and showed a downtrend except the radish shoot. The concentrations of heavy metals (Cu, Zn, and Cd) in vegetables of Baiyin were higher than those of Liujiaxia. In the meanwhile, the uptake contents continued to increase during the growth or halted at maximum at a certain stage. The maximum uptake rates were found on the maturity except for the shoot of radish which took place at the exponential growth stages of root. The sigmoid model could simulate the dynamic processes of growth and heavy metals uptake of Chinese cabbage and radish. Conclusively, heavy metals have higher bioaccumulation tendency for roots in Chinese cabbage and for shoots in radish.

Internalization and Subcellular Trafficking of Poly-l-lysine Dendrimers Are Impacted by the Site of Fluorophore Conjugation.

PubMed

Avaritt, Brittany R; Swaan, Peter W

2015-06-01

Internalization and intracellular trafficking of dendrimer-drug conjugates play an important role in achieving successful drug delivery. In this study, we aimed to elucidate the endocytosis mechanisms and subcellular localization of poly-l-lysine (PLL) dendrimers in Caco-2 cells. We also investigated the impact of fluorophore conjugation on cytotoxicity, uptake, and transepithelial transport. Oregon green 514 (OG) was conjugated to PLL G3 at either the dendrimer periphery or the core. Chemical inhibitors of clathrin-, caveolin-, cholesterol-, and dynamin-mediated endocytosis pathways and macropinocytosis were employed to establish internalization mechanisms, while colocalization with subcellular markers was used to determine dendrimer trafficking. Cell viability, internalization, and uptake were all influenced by the site of fluorophore conjugation. Uptake was found to be highly dependent on cholesterol- and dynamin-mediated endocytosis as well as macropinocytosis. Dendrimers were trafficked to endosomes and lysosomes, and subcellular localization was impacted by the fluorophore conjugation site. The results of this study indicate that PLL dendrimers exploit multiple pathways for cellular entry, and internalization and trafficking can be impacted by conjugation. Therefore, design of dendrimer-drug conjugates requires careful consideration to achieve successful drug delivery.

Effect of (18)F-fluorodeoxyglucose extravasation on time taken for tumoral uptake to reach a plateau: animal and clinical PET analyses.

PubMed

Lee, Jong Jin; Chung, Jin Hwa; Kim, Seog-Young

2016-10-01

The present study aimed to investigate the effect of (18)F-fluorodeoxyglucose (FDG) extravasation on the time taken for tumoral uptake to reach a plateau. For the animal experiment, FDG extravasation was conducted in the tails of HCT116 tumor-bearing xenograft mice models in three groups (no extravasation, 40 % extravasation, and 80 % extravasation; n = 5, each). Dynamic positron emission tomography (PET) images were acquired over a period of 2 h following injection. Time-activity curves for FDG in the tails and tumors were calculated. For the clinical experiment, 22 patients (male:female, 14:8; age range, 70.8 ± 9.2 years) were subjected to PET/computed tomography (PET/CT) 1 h after the injection of FDG. The inclusion criteria were as follows: (1) submitted to both whole-body and subsequent regional scanning; (2) entire extravasation activity visualized in the whole-body images; (3) tumor visualized on both whole-body and additional regional images; and (4) status of tumor either confirmed by biopsy or clinically suspected for malignancy. The standardized uptake values (SUVs) of the tumors (on the whole-body and additional PET images) and extravasation sites were recorded. There were no significant differences in the time taken for tumoral uptake to reach a plateau and that to reach minimum activity at the extravasation site among the three groups of mice. However, the mean tumoral activity and activity at the extravasation site were negatively correlated at 1 h post-injection. According to the clinical PET findings, the differences in SUV between the whole-body and regional images were not significantly correlated with the interval between injection of FDG and start of whole-body scanning, interval between the start of whole-body scanning and start of regional scanning, extravasation volume, maximum SUV of the extravasation site, or total activity at the extravasation site. The time taken for tumoral uptake to reach a plateau is not affected by extravasation, even at extensive degrees. Thus, in routine practice, the imaging time of approximately 60 min post-injection need not be modified even if extravasation is identified. However, tumor SUV may be underestimated in cases of extravasation.

Soil methane oxidation in both dry and wet temperate eucalypt forests shows a near-identical relationship with soil air-filled porosity

NASA Astrophysics Data System (ADS)

Fest, Benedikt J.; Hinko-Najera, Nina; Wardlaw, Tim; Griffith, David W. T.; Livesley, Stephen J.; Arndt, Stefan K.

2017-01-01

Well-drained, aerated soils are important sinks for atmospheric methane (CH4) via the process of CH4 oxidation by methane-oxidising bacteria (MOB). This terrestrial CH4 sink may contribute towards climate change mitigation, but the impact of changing soil moisture and temperature regimes on CH4 uptake is not well understood in all ecosystems. Soils in temperate forest ecosystems are the greatest terrestrial CH4 sink globally. Under predicted climate change scenarios, temperate eucalypt forests in south-eastern Australia are predicted to experience rapid and extreme changes in rainfall patterns, temperatures and wild fires. To investigate the influence of environmental drivers on seasonal and inter-annual variation of soil-atmosphere CH4 exchange, we measured soil-atmosphere CH4 exchange at high-temporal resolution (< 2 h) in a dry temperate eucalypt forest in Victoria (Wombat State Forest, precipitation 870 mm yr-1) and in a wet temperature eucalypt forest in Tasmania (Warra Long-Term Ecological Research site, 1700 mm yr-1). Both forest soil systems were continuous CH4 sinks of -1.79 kg CH4 ha-1 yr-1 in Victoria and -3.83 kg CH4 ha-1 yr-1 in Tasmania. Soil CH4 uptake showed substantial temporal variation and was strongly controlled by soil moisture at both forest sites. Soil CH4 uptake increased when soil moisture decreased and this relationship explained up to 90 % of the temporal variability. Furthermore, the relationship between soil moisture and soil CH4 flux was near-identical at both forest sites when soil moisture was expressed as soil air-filled porosity (AFP). Soil temperature only had a minor influence on soil CH4 uptake. Soil nitrogen concentrations were generally low and fluctuations in nitrogen availability did not influence soil CH4 uptake at either forest site. Our data suggest that soil MOB activity in the two forests was similar and that differences in soil CH4 exchange between the two forests were related to differences in soil moisture and thereby soil gas diffusivity. The differences between forest sites and the variation in soil CH4 exchange over time could be explained by soil AFP as an indicator of soil moisture status.

Integrated MRI and [11 C]-PBR28 PET Imaging in Amyotrophic Lateral sclerosis.

PubMed

Alshikho, Mohamad J; Zürcher, Nicole R; Loggia, Marco L; Cernasov, Paul; Reynolds, Beverly; Pijanowski, Olivia; Chonde, Daniel B; Izquierdo Garcia, David; Mainero, Caterina; Catana, Ciprian; Chan, James; Babu, Suma; Paganoni, Sabrina; Hooker, Jacob M; Atassi, Nazem

2018-05-08

To characterize [ 11 C]-PBR28 brain uptake using positron emission tomography (PET) in people with amyotrophic lateral sclerosis (ALS), and primary lateral sclerosis (PLS). We have previously shown increased [ 11 C]-PBR28 uptake in the precentral gyrus in a small group of ALS patients. Herein, we confirm our initial finding, study the longitudinal changes, and characterize the gray vs. white matter distribution of [ 11 C]-PBR28 uptake in a larger cohort of patients with ALS and PLS. Eighty-five participants including 53 ALS, 11 PLS and 21 healthy controls underwent integrated [ 11 C]-PBR28 PET-MR brain imaging. Patients were clinically assessed using the upper motor neuron burden (UMNB), and the revised ALS functional rating scale (ALSFRS-R). [ 11 C]-PBR28 uptake was quantified as standardized uptake value ratio (SUVR), and compared between groups. Cortical thickness, and fractional anisotropy were compared between groups and correlated with SUVR and the clinical data. [ 11 C]-PBR28 uptake and ALSFRS-R were compared longitudinally over six-month in ten ALS individuals. Whole brain voxel-wise, surface-based and region of interest analyses revealed increased [ 11 C]-PBR28 uptake in the precentral and paracentral gyri in ALS, and in the sub-cortical white matter for the same regions in PLS, compared to controls. The increase in [ 11 C]-PBR28 uptake co-localized and correlated with cortical thinning, reduced fractional anisotropy, increased mean diffusivity, and correlated with higher UMNB score. No significant changes were detected in [ 11 C]-PBR28 uptake over six-month despite clinical progression. Glial activation measured by in vivo [ 11 C]-PBR28 PET is increased in pathologically relevant regions in people with ALS and correlates with clinical measures. This article is protected by copyright. All rights reserved. © 2018 American Neurological Association.

Uptake of Al, As, Cr, Cd, Cu, Fe, Mn, Ni, Pb, Sr, and Zn in native wheatgrasses, wildryes, and bluegrass on three metal-contaminated soils from Montana

USDA-ARS?s Scientific Manuscript database

One of the biggest challenges to successfully phytoremediate contaminated mineland soils is the identification of native plants that possess a broad adaptation to ecological sites and either exclude or uptake heavy metals of interest. This study evaluated forage concentrations of aluminum (Al), ars...

Examining College Students' Uptake of Facebook through the Lens of Domestication Theory

ERIC Educational Resources Information Center

Lohnes Watulak, Sarah; Whitfield, Dean

2016-01-01

Given the prevalence of social network sites (SNS) uptake among college students, and Facebook use in particular, we seek to understand the variety of ways in which Facebook is embedded in the routine, everyday lives of undergraduates. In addition to Facebook use, we aim to shed light on non-use; why do some American undergraduates choose to use…

Ozone exposure, uptake, and response of different-sized black cherry trees

Treesearch

Todd S. Frederickson; John M. Skelly; Kim C. Steiner; Thomas E. Kolb

1996-01-01

Differences in exposure, uptake and relative sensitivity to ozone between seedling, sapling, and canopy black cherry (Prunus serotina Ehrh.) trees were characterized during two growing seasons in north central Pennsylvania. Open-grown trees of all sizes received a similar amount of ozone exposure. Seedlings had greater foliar ozone injury, expressed...

Water Uptake along the Length of Grapevine Fine Roots: Developmental anatomy, tissue specific aquaporin expression, and pathways of water transport

USDA-ARS?s Scientific Manuscript database

To better understand water uptake patterns in root systems of woody perennial crops, we detailed the developmental anatomy and hydraulic physiology along the length of grapevine fine roots- from the tip to secondary growth zones. Our characterization included localization of suberized structures an...

Characterization of dopamine releasable and reserve pools in Drosophila larvae using ATP/P2X2-mediated stimulation

PubMed Central

Xiao, Ning; Venton, B. Jill

2015-01-01

Dopaminergic signaling pathways are conserved between mammals and Drosophila, but the factors important for maintaining the functional pool of synaptic dopamine are not fully understood in Drosophila. In this study, we characterized the releasable and reserve dopamine pools in Drosophila larvae using ATP/ P2X2-mediated stimulation. Dopamine release was stable with stimulations performed at least every 5 min but decayed with stimulations performed 2 min apart or less, indicating the replenishment of the releasable pool occurred on a time scale between 2 and 5 min. Dopamine synthesis or uptake were pharmacologically inhibited with 3-iodotyrosine and cocaine, respectively, to evaluate their contributions to maintaining the releasable dopamine pool. We found that both synthesis and uptake were needed to maintain the releasable dopamine pool, with synthesis playing a major part in long-term replenishment and uptake being more important for short-term replenishment. These effects of synthesis and uptake on different time scales in Drosophila are analogous to mammals. However, unlike in mammals, cocaine did not activate a reserve pool of dopamine in Drosophila when using P2X2 stimulations. Our study shows that both synthesis and uptake replenish the releasable pool, providing a better understanding of dopamine regulation in Drosophila. PMID:25951875

Pharmacological characterization of a fluorescent uptake assay for the noradrenaline transporter.

PubMed

Haunsø, Anders; Buchanan, Dawn

2007-04-01

The noradrenaline transporter (NET) is a Na(+)/Cl(-) dependent monoamine transporter that mediates rapid clearance of noradrenaline from the synaptic cleft, thereby terminating neuronal signaling. NET is an important target for drug development and is known to be modulated by many psychoactive compounds, including psychostimulants and antidepressants. Here, the authors describe the development and pharmacological characterization of a nonhomogeneous fluorescent NET uptake assay using the compound 4-(4-dimethylaminostyryl)-N-methylpyridinium (ASP(+)). Data presented show that the pharmacology of both the classic radiolabeled (3)H-noradrenaline- and ASP(+)-based uptake assays are comparable, with an excellent correlation between potency obtained for known modulators of NET (r = 0.95, p < 0.0001). Furthermore, the fluorescent uptake assay is highly reproducible and has sufficiently large Z' values to be amenable for high-throughput screening (HTS). The advantage of this assay is compatibility with both 96- and 384-well formats and lack of radioactivity usage. Thus, the authors conclude that the assay is an inexpensive, viable approach for the identification and pharmacological profiling of small-molecule modulators of the monoamine transporter NET and may be amenable for HTS.

The nitrogen budget for different forest types in the central Congo Basin

NASA Astrophysics Data System (ADS)

Bauters, Marijn; Verbeeck, Hans; Cizungu, Landry; Boeckx, Pascal

2016-04-01

Characterization of fundamental processes in different forest types is vital to understand the interaction of forests with their changing environment. Recent data analyses, as well as modeling activities have shown that the CO2 uptake by terrestrial ecosystems strongly depends on site fertility, i.e. nutrient availability. Accurate projections of future net forest growth and terrestrial CO2 uptake thus necessitate an improved understanding on nutrient cycles and how these are coupled to the carbon (C) cycle in forests. This holds especially for tropical forests, since they represent about 40-50% of the total carbon that is stored in terrestrial vegetation, with the Amazon basin and the Congo basin being the largest two contiguous blocks. However, due to political instability and reduced accessibility in the central Africa region, there is a strong bias in scientific research towards the Amazon basin. Consequently, central African forests are poorly characterized and their role in global change interactions shows distinct knowledge gaps, which is important bottleneck for all efforts to further optimize Earth system models explicitly including this region. Research in the Congo Basin region should combine assessments of both carbon stocks and the underlying nutrient cycles which directly impact the forest productivity. We set up a monitoring network for carbon stocks and nitrogen fluxes in four different forest types in the Congo Basin, which is now operative. With the preliminary data, we can get a glimpse of the differences in nitrogen budget and biogeochemistry of African mixed lowland rainforest, monodominant lowland forest, mixed montane forest and eucalypt plantations.

Development and Characterization of Nanoembedded Microparticles for Pulmonary Delivery of Antitubercular Drugs against Experimental Tuberculosis.

PubMed

Goyal, Amit Kumar; Garg, Tarun; Rath, Goutam; Gupta, Umesh Datta; Gupta, Pushpa

2015-11-02

The foremost objective of the present research study was to develop and evaluate the potential of rifampicin (RIF) and isoniazid (INH) loaded spray dried nanoembedded microparticles against experimental tuberculosis (TB). In this study, RIF-INH loaded various formulations (chitosan, guar gum, mannan, and guar gum coated chitosan) were prepared by spray drying and characterized on the basis of in vitro as well as in vivo studies. Results showed that guar gum spray dried particles showed uniform size distribution with smooth surface as compare to mannan formulations. Guar gum batches exhibited excellent flow ability attributed to their optimum moisture content and uniform size distribution. The drug release showed the biphasic pattern of release, i.e., initial burst followed by a sustained release pattern. The preferential uptake of guar gum coated formulations suggested the presence and selective uptake capability of mannose moiety to the specific cell surface of macrophages. In vivo lung distribution study showed that guar gum coated chitosan (GCNP) batches demonstrated prolonged residence at the target site and thereby improve the therapeutic utility of drug with a significant reduction in systemic toxicity. Optimized drug loaded GCNP formulation has resulted in almost 5-fold reduction of the number of bacilli as compared to control group. Histopathology study also demonstrated that none of the treated groups show any evidence of lung tissue abnormality. Hence, GCNPs could be a promising carrier for selective delivery of antitubercular drugs to alveolar macrophages with the interception of minimal side effects, for efficient management of TB.

Feasibility of Using Phytoextraction to Remediate a Compost-Based Soil Contaminated with Cadmium.

PubMed

Parisien, Michele A; Rutter, Allison; Zeeb, Barbara A

2015-01-01

Greenhouse and in-situ field experiments were used to determine the potential for phytoextraction to remediate soil contaminated with Cd from municipal solid waste (MSW) and sewage sludge (SS) compost application at a Peterborough (Canada) site. For the greenhouse experiment, one native (Chenopodium album) and three naturalized (Poa compressa, Brassica juncea, Helianthus annuus) plant species were planted in soil containing no detectable Cd (<1.0 μg·g(-1)), and soil from the site containing low (5.0 ± 0.3 μg·g(-1) Cd), and high (16.5 ± 1.2 μg⋅g(-1) Cd) Cd concentrations. Plant uptake was low (root BAFs ≤0.5) for all species except P. compressa in the low Cd treatment (BAF 1.0). Only B. juncea accumulated Cd in its shoots, though uptake was low (BAF ≤0.3). For the field experiment, B. juncea was planted in-situ in areas of low and high Cd concentrations. Brassica juncea Cd uptake was low (root and shoot BAFs <0.2) in both treatments. Sequential extraction analysis indicated that Cd is retained primarily by low bioavailability soil fractions, and phytoextraction is therefore not feasible at this site. Though low Cd bioavailability has negative implications for Cd phytoextraction from MSW/SS compost-based soils, it may limit receptor exposure to Cd sufficiently to eliminate the potential for risk at this site.

The Global Influence of Cloud Optical Thickness on Terrestrial Carbon Uptake

NASA Astrophysics Data System (ADS)

Zhu, P.; Cheng, S. J.; Keppel-Aleks, G.; Butterfield, Z.; Steiner, A. L.

2016-12-01

Clouds play a critical role in regulating Earth's climate. One important way is by changing the type and intensity of solar radiation reaching the Earth's surface, which impacts plant photosynthesis. Specifically, the presence of clouds modifies photosynthesis rates by influencing the amount of diffuse radiation as well as the spectral distribution of solar radiation. Satellite-derived cloud optical thickness (COT) may provide the observational constraint necessary to assess the role of clouds on ecosystems and terrestrial carbon uptake across the globe. Previous studies using ground-based observations at individual sites suggest that below a COT of 7, there is a greater increase in light use efficiency than at higher COT values, providing evidence for higher carbon uptake rates than expected given the reduction in radiation by clouds. However, the strength of the COT-terrestrial carbon uptake correlation across the globe remains unknown. In this study, we investigate the influence of COT on terrestrial carbon uptake on a global scale, which may provide insights into cloud conditions favorable for plant photosynthesis and improve our estimates of the land carbon sink. Global satellite-derived MODIS data show that tropical and subtropical regions tend to have COT values around or below the threshold during growing seasons. We find weak correlations between COT and GPP with Fluxnet MTE global GPP data, which may be due to the uncertainty of upscaling GPP from individual site measurements. Analysis with solar-induced fluorescence (SIF) as a proxy for GPP is also evaluated. Overall, this work constructs a global picture of the role of COT on terrestrial carbon uptake, including its temporal and spatial variations.

Cloning and functional characterization of the high-affinity K+ transporter HAK1 of pepper.

PubMed

Martínez-Cordero, M Angeles; Martínez, Vicente; Rubio, Francisco

2004-10-01

High-affinity K+ uptake in plants plays a crucial role in K+ nutrition and different systems have been postulated to contribute to the high-affinity K+ uptake. The results presented here with pepper (Capsicum annum) demonstrate that a HAK1-type transporter greatly contributes to the high-affinity K+ uptake observed in roots. Pepper plants starved of K+ for 3 d showed high-affinity K+ uptake (Km of 6 microM K+) that was very sensitive to NH and their roots expressed a high-affinity K+ transporter, CaHAK1, which clusters in group I of the KT/HAK/KUP family of transporters. When expressed in yeast ( Saccharomyces cerevisiae ), CaHAK1 mediated high-affinity K+ and Rb+ uptake with Km values of 3.3 and 1.9 microM, respectively. Rb+ uptake was competitively inhibited by micromolar concentrations of NH and Cs+, and by millimolar concentrations of Na+.

Is there a strategy I iron uptake mechanism in maize?

PubMed

Li, Suzhen; Zhou, Xiaojin; Chen, Jingtang; Chen, Rumei

2018-04-03

Iron is a metal micronutrient that is essential for plant growth and development. Graminaceous and nongraminaceous plants have evolved different mechanisms to mediate Fe uptake. Generally, strategy I is used by nongraminaceous plants like Arabidopsis, while graminaceous plants, such as rice, barley, and maize, are considered to use strategy II Fe uptake. Upon the functional characterization of OsIRT1 and OsIRT2 in rice, it was suggested that rice, as an exceptional graminaceous plant, utilizes both strategy I and strategy II Fe uptake systems. Similarly, ZmIRT1 and ZmZIP3 were identified as functional zinc and iron transporters in the maize genome, along with the determination of several genes encoding Zn and Fe transporters, raising the possibility that strategy I Fe uptake also occurs in maize. This mini-review integrates previous reports and recent evidence to obtain a better understanding of the mechanisms of Fe uptake in maize.

SITE SITE DISTURBANCE EFFECTS ON A CLAY SOIL UNDER PINUS RADIATA - ROOT BIOMASS, MYCORRHIZAL COLONISATION, 15AMMONIUM UPTAKE, AND FOLIAR NUTRIENT LEVELS

EPA Science Inventory

Timber harvesting can result in adverse physical, chemical and biological alterations to soil. The objective of this study was to examine the effects of site disturbance to determine the extent and duration of possible harvesting impacts on soil chemical and biological propertie...

Mechanism of Aluminum Inhibition of Net 45Ca2+ Uptake by Amaranthus Protoplasts 1

PubMed Central

Rengel, Zdenko; Elliott, Daphne C.

1992-01-01

Calcium ions serve as a second messenger in signal transduction and metabolic regulation. Effects of Al on calcium homeostasis remain to be elucidated. Short-term net 45Ca2+ uptake by Amaranthus tricolor protoplasts was monitored from uptake media prepared to test the influence of pH, Al, and various inhibitors. Accumulation of 45Ca2+ increased during the first 3 to 6 minutes and then leveled off or declined. Al and Ca2+ channel blockers (verapamil and bepridil) decreased net 45Ca2+ uptake. This decrease was more pronounced when Al and bepridil were both present in uptake media, but Al did not aggravate verapamil-induced reduction of net 45Ca2+ uptake. Erythrosin B and calmidazolium each increased net 45Ca2+ uptake, probably by interfering with Ca2+ efflux. This effect was undetectable in the presence of Al. Mycophenolic acid decreased net 45Ca2+ uptake; guanosine alleviated this effect. Al-induced reduction of net 45Ca2+ uptake was not aggravated by mycophenolic acid. Net 45Ca2+ uptake was generally less at pH 4.5 than at 5.5 for all treatments. It is concluded that Al ions affect net 45Ca2+ uptake by binding to the verapamil-specific channel site that is different from the bepridil-specific one, as well as by interfering with the action of guanosine 5′-triphosphate-binding proteins. PMID:16668688

Nitrogen dynamics in Turbic Cryosols from Siberia and Greenland.

PubMed

Wild, Birgit; Schnecker, Jörg; Bárta, Jiří; Capek, Petr; Guggenberger, Georg; Hofhansl, Florian; Kaiser, Christina; Lashchinsky, Nikolaj; Mikutta, Robert; Mooshammer, Maria; Santrůčková, Hana; Shibistova, Olga; Urich, Tim; Zimov, Sergey A; Richter, Andreas

2013-12-01

Turbic Cryosols (permafrost soils characterized by cryoturbation, i.e., by mixing of soil layers due to freezing and thawing) are widespread across the Arctic, and contain large amounts of poorly decomposed organic material buried in the subsoil. This cryoturbated organic matter exhibits retarded decomposition compared to organic material in the topsoil. Since soil organic matter (SOM) decomposition is known to be tightly linked to N availability, we investigated N transformation rates in different soil horizons of three tundra sites in north-eastern Siberia and Greenland. We measured gross rates of protein depolymerization, N mineralization (ammonification) and nitrification, as well as microbial uptake of amino acids and NH 4 + using an array of 15 N pool dilution approaches. We found that all sites and horizons were characterized by low N availability, as indicated by low N mineralization compared to protein depolymerization rates (with gross N mineralization accounting on average for 14% of gross protein depolymerization). The proportion of organic N mineralized was significantly higher at the Greenland than at the Siberian sites, suggesting differences in N limitation. The proportion of organic N mineralized, however, did not differ significantly between soil horizons, pointing to a similar N demand of the microbial community of each horizon. In contrast, absolute N transformation rates were significantly lower in cryoturbated than in organic horizons, with cryoturbated horizons reaching not more than 32% of the transformation rates in organic horizons. Our results thus indicate a deceleration of the entire N cycle in cryoturbated soil horizons, especially strongly reduced rates of protein depolymerization (16% of organic horizons) which is considered the rate-limiting step in soil N cycling.

Fluorescent solute-partitioning characterization of layered soft contact lenses.

PubMed

Dursch, T J; Liu, D E; Oh, Y; Radke, C J

2015-03-01

Partitioning of aqueous packaging, wetting, and care-solution agents into and out of soft contact lenses (SCLs) is important for improving wear comfort and also for characterizing lens physico-chemical properties. We illustrate both features of partitioning by application of fluorescent-solute partitioning into DAILIES TOTAL1® (delefilcon A) water-gradient SCLs, which exhibit a layered structure of a silicone-hydrogel (SiHy) core sandwiched between thin surface-gel layers. Two-photon fluorescence confocal laser-scanning microscopy and attenuated total-reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) characterize the lens and assess uptake profiles of six prototypical fluorescent solutes. Comparison of solute uptake in a SiHy-core prototype lens (i.e., O2OPTIX(TM)) validates the core SiHy structure of DAILIESTOTAL1®. To establish surface-layer charge, partition coefficients and water contents are obtained for aqueous pH values of 4 and 7.4. Solute fluorescence-intensity profiles clearly confirm a layered structure for the DAILIES TOTAL1® lenses. In all cases, aqueous solute partition coefficients are greater in the surface layers than in the SiHy core, signifying higher water in the surface gels. ATR-FTIR confirms surface-layer mass water contents of 82±3%. Water uptake and hydrophilic-solute uptake at pH 4 compared with that at pH 7.4 reveal that the surface-gel layers are anionic at physiologic pH 7.4, whereas both the SiHy core and O2OPTIX™ (lotrafilcon B) are nonionic. We successfully confirm the layered structure of DAILIES TOTAL1®, consisting of an 80-μm-thick SiHy core surrounded by 10-μm-thick polyelectrolyte surface-gel layers of significantly greater water content and aqueous solute uptake compared with the core. Accordingly, fluorescent-solute partitioning in SCLs provides information on gel structure and composition, in addition to quantifying uptake and release amounts and rates. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Cold tuberculous abscess identified by FDG PET.

PubMed

Yago, Yuzo; Yukihiro, Masashi; Kuroki, Hirofumi; Katsuragawa, Yuzo; Kubota, Kazuo

2005-09-01

We report FDG PET of two cases of cold abscess due to Mycobacterium tuberculosis. Case 1 had colon cancer; FDG PET showed high FDG uptake in the colon lesion and low uptake in the inguinal lesion. The latter was a tuberculous cold abscess confirmed by CT/MRI and biopsy. Case 2 received radiotherapy for lung cancer and presented with suspected vertebral metastasis. Further studies revealed tuberculosis of the vertebra and a tuberculous cold abscess in the iliopsoas muscle. FDG PET showed moderate uptake in the third lumbar spine and low uptake in the abscess center of iliopsoas lesion. Both tuberculous cold abscesses showed moderate FDG uptake in the capsule and low uptake in the center. These features are unique compared with non-tuberculous abscess and typical tuberculosis lesions, which are characterized by high FDG uptake. Pathologically, tuberculous cold abscess is not accompanied by active inflammatory reaction. Our findings suggested that the FDG uptake by tuberculous lesion varies according to the grade of inflammatory activity. The new diagnostic features of tuberculous cold abscess may be useful in the evaluation of such lesions by FDG PET.

137Cs soil-to-plant transfer for individual species in a semi-natural grassland. Influence of potassium soil content.

PubMed

Ciuffo, Liliana; Velasco, Hugo; Belli, Mar; Sansone, Umberto

2003-09-01

In the present study we assessed the radiocaesium uptake by plants in order to piece together information on factors affecting the uptake processes, particularly K supply and plant species differences. Vegetation uptake from soil contaminated by the Chernobyl accident was compared at two semi-natural grasslands. The Cs/K discrimination factor (DF), which is often used to evaluate a plant's efficiency in absorbing nutrients from soil, was estimated. The obtained DF values (0.01 to 0.8) vary with K soil concentrations and plant species, indicating that the (40)K is more efficiently absorbed than (137)Cs. The soil-to-plant relationship was evaluated by means of the transfer factor (TF). The (137)Cs TF(sp) values obtained from separated plant species varied within the range of 0.016 to 0.400 (site 1) and 0.017 to 0.171 (site 2). When mixed grass samples were considered a large variation was observed, mainly for site 1. The (137)Cs TF(mix) ranges were: 0.018 to 0.250 for site 1 and 0.017 to 0.167 for site 2. These values fall within the range of TFs commonly reported (0.0001-1). Our present data suggest that these pastures are apt for forage use. Different plant species presented different individual behavior regarding their (137)Cs TF(sp) when the (40)K soil activity concentration was taken in account. For most of the species analyzed, we observed a gradual decrease in the individual (137)Cs TF(sp) when the (40)K soil activity concentration was increased, with the exception of Taraxacum officinale at one of the sampling sites.

Characterization of nicosulfuron availability in aged soils.

PubMed

Regitano, Jussara B; Koskinen, William C

2008-07-23

Sorption-desorption interactions of pesticides with soil determine their availability for transport, plant uptake, and microbial degradation. These interactions are affected by the physical-chemical properties of the pesticide and soil, and for some pesticides, their residence time in the soil. This research evaluated changes in sorption/availability of nicosulfuron (2-[[[[(4,6-dimethoxy-2-pyrimidinyl]amino]carbonyl]amino]sulfonyl]-N,N-dimethyl-3-pyridinecarboxamide) herbicide with aging in different soils, using a radiolabeled ((14)C) tracer. Aging significantly increased sorption. For instance, after the 41-day incubation, calculated K d,app increased by a factor of 2 to 3 in Mollisols from the Midwestern United States and by a factor of 5 to 9 in Oxisols from Brazil and Hawaii, as compared to freshly treated soils. In view of this outcome, potential transport of nicosulfuron would be overpredicted if freshly treated soil K d values were used to predict transport. The fact that the nicosulfuron solution concentration decreased faster than the soil concentration with time suggested that the increase in sorption was because the rate of degradation in solution and on labile sites was faster than the rate of desorption of the neutral species from the soil particles. It may have also been due to nicosulfuron anion diffusion to less accessible sites with time, leaving the more strongly bound neutral molecules for the sorption characterization. Regardless of the mechanism, these results are further evidence that increases in sorption during pesticide aging should be taken into account during the characterization of the sorption process for mathematical models of pesticide degradation and transport.

Selective labeling of serotonin uptake sites in rat brain by (/sup 3/H)citalopram contrasted to labeling of multiple sites by (/sup 3/H)imipramine

DOE Office of Scientific and Technical Information (OSTI.GOV)

D'Amato, R.J.; Largent, B.L.; Snowman, A.M.

1987-07-01

Citalopram is a potent and selective inhibitor of neuronal serotonin uptake. In rat brain membranes (/sup 3/H)citalopram demonstrates saturable and reversible binding with a KD of 0.8 nM and a maximal number of binding sites (Bmax) of 570 fmol/mg of protein. The drug specificity for (/sup 3/H)citalopram binding and synaptosomal serotonin uptake are closely correlated. Inhibition of (/sup 3/H)citalopram binding by both serotonin and imipramine is consistent with a competitive interaction in both equilibrium and kinetic analyses. The autoradiographic pattern of (/sup 3/H)citalopram binding sites closely resembles the distribution of serotonin. By contrast, detailed equilibrium-saturation analysis of (/sup 3/H)imipramine bindingmore » reveals two binding components, i.e., high affinity (KD = 9 nM, Bmax = 420 fmol/mg of protein) and low affinity (KD = 553 nM, Bmax = 8560 fmol/mg of protein) sites. Specific (/sup 3/H)imipramine binding, defined as the binding inhibited by 100 microM desipramine, is displaced only partially by serotonin. Various studies reveal that the serotonin-sensitive portion of binding corresponds to the high affinity sites of (/sup 3/H)imipramine binding whereas the serotonin-insensitive binding corresponds to the low affinity sites. Lesioning of serotonin neurons with p-chloroamphetamine causes a large decrease in (/sup 3/H)citalopram and serotonin-sensitive (/sup 3/H)imipramine binding with only a small effect on serotonin-insensitive (/sup 3/H)imipramine binding. The dissociation rate of (/sup 3/H)imipramine or (/sup 3/H)citalopram is not altered by citalopram, imipramine or serotonin up to concentrations of 10 microM. The regional distribution of serotonin sensitive (/sup 3/H)imipramine high affinity binding sites closely resembles that of (/sup 3/H)citalopram binding.« less

Temporal variations in arsenic uptake by rice plants in Bangladesh: the role of iron plaque in paddy fields irrigated with groundwater

PubMed Central

Garnier, J.-M.; Travassac, F.; Lenoble, V.; Rose, J.; Zheng, Y.; Hossain, M.S.; Chowdhury, S. H.; Biswas, A. K.; Ahmed, K.M.; Cheng, Z.; van Geen, A.

2010-01-01

The transfer of arsenic to rice grains is a human health issue of growing relevance in regions of southern Asia where shallow groundwater used for irrigation of paddy fields is elevated in As. In the present study, As and Fe concentrations in soil water and in the roots of rice plants, primarily the Fe plaque surrounding the roots, were monitored during the 4-month growing season at two sites irrigated with groundwater containing ~130 μg/L As and two control sites irrigated with water containing <15 μg/L As. At both sites irrigated with contaminated water, As concentrations in soil water increased from <10 μg/L to >1000 μg/L during the first five weeks of the growth season and then gradually declined to <10 μg/L during the last five weeks. At the two control sites, concentrations of As in soil water never exceeded 40 μg/L. At both contaminated sites, the As content of roots and Fe plaque rose to 1000-1500 mg/kg towards the middle of the growth season. It then declined to ~300 mg/kg towards the end, a level still well above As concentration of ~100 mg/kg in roots and plaque measured throughout the growing season at the two control sites. These time series, combined with simple mass balance considerations, demonstrate that the formation of Fe plaque on the roots of rice plants by micro-aeration significant limits uptake of As by rice plants grown in paddy fields. Large variations in the As and Fe content of plant stems at two of the sites irrigated with contaminated water and one of the control sites were also recorded. The origin of these variations, particularly during the last month of the growth season, need to be better understood because they are likely to influence uptake of As in rice grains. PMID:20576285

Potential role of combined FDG PET/CT & contrast enhancement MRI in a rectal carcinoma model with nodal metastases characterized by a poor FDG-avidity.

PubMed

Farace, Paolo; Conti, Giamaica; Merigo, Flavia; Tambalo, Stefano; Marzola, Pasquina; Sbarbati, Andrea; Quarta, Carmelo; D'Ambrosio, Daniela; Chondrogiannis, Sotirios; Nanni, Cristina; Rubello, Domenico

2012-04-01

To investigate the additional role of MRI contrast enhancement (CE) in the primary tumor and the FDG uptake at PET in the lymph-node metastases. A model of colorectal cancer induced by orthotopic HT-29 cells microinjection, producing pelvic lymph node metastases, was assessed using CE-MRI and FDG-PET. Histology and GLUT-1 immunohistochemistry were performed on primary tumors and iliac lymph nodes. Primary tumors were characterized by low FDG-uptake but high CE-MRI, particularly at tumor periphery. Undetectable FDG-uptake characterized the metastatic lymph-nodes. Histology revealed large stromal bundles at tumor periphery and a dense network of stromal fibers and neoplastic cells in the inner portion of the tumors. Both primary tumors and positive lymph nodes showed poor GLUT-1 staining. Our data support the complementary role of MRI-CE and FDG PET in some types of carcinomas characterized by abundant cancer-associated stroma and poor FDG avidity consequent to poor GLUT-1 transported. In these tumors FDG-PET alone may be not completely adequate to obtain an adequate tumor radiotherapy planning, and a combination with dual CE-MRI is strongly recommended. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

NF-κB p65 Subunit Mediates Lipopolysaccharide-Induced Na+/I− Symporter Gene Expression by Involving Functional Interaction with the Paired Domain Transcription Factor Pax8

PubMed Central

Nicola, Juan Pablo; Nazar, Magalí; Mascanfroni, Iván Darío; Pellizas, Claudia Gabriela; Masini-Repiso, Ana María

2010-01-01

The Gram-negative bacterial endotoxin lipopolysaccharide (LPS) elicits a variety of biological responses. Na+/I− symporter (NIS)-mediated iodide uptake is the main rate-limiting step in thyroid hormonogenesis. We have recently reported that LPS stimulates TSH-induced iodide uptake. Here, we further analyzed the molecular mechanism involved in the LPS-induced NIS expression in Fisher rat thyroid cell line 5 (FRTL-5) thyroid cells. We observed an increase in TSH-induced NIS mRNA expression in a dose-dependent manner upon LPS treatment. LPS enhanced the TSH-stimulated NIS promoter activity denoting the NIS-upstream enhancer region (NUE) as responsible for the stimulatory effects. We characterized a novel putative conserved κB site for the transcription factor nuclear factor-κB (NF-κB) within the NUE region. NUE contains two binding sites for the transcription factor paired box 8 (Pax8), main regulator of NIS transcription. A physical interaction was observed between the NF-κB p65 subunit and paired box 8 (Pax8), which appears to be responsible for the synergic effect displayed by these transcription factors on NIS gene transcription. Moreover, functional blockage of NF-κB signaling and site-directed mutagenesis of the κB cis-acting element abrogated LPS stimulation. Silencing expression of p65 confirmed its participation as an effector of LPS-induced NIS stimulation. Furthermore, chromatin immunoprecipitation corroborated that NIS is a novel target gene for p65 transactivation in response to LPS. Moreover, we were able to corroborate the LPS-stimulatory effect on thyroid cells in vivo in LPS-treated rats, supporting that thyrocytes are capable of responding to systemic infections. In conclusion, our results reveal a new mechanism involving p65 in the LPS-induced NIS expression, denoting a novel aspect in thyroid cell differentiation. PMID:20667985

Optical tracer size differences allow quantitation of active pumping rate versus Stokes-Einstein diffusion in lymphatic transport

NASA Astrophysics Data System (ADS)

DSouza, Alisha V.; Marra, Kayla; Gunn, Jason R.; Samkoe, Kimberley S.; Pogue, Brian W.

2016-10-01

Lymphatic uptake of interstitially administered agents occurs by passive convective-diffusive inflow driven by interstitial concentration and pressure, while the downstream lymphatic transport is facilitated by active propulsive contractions of lymphatic vessel walls. Near-infrared fluorescence imaging in mice was used to measure these central components of lymphatic transport for the first time, using two different-sized molecules-methylene blue (MB) and fluorescence-labeled antibody immunoglobulin G (IgG)-IRDye 680RD. This work confirms the hypothesis that lymphatic passive inflow and active propulsion rates can be separated based upon the relative differences in Stokes-Einstein diffusion coefficient. This coefficient specifically affects the passive-diffusive uptake when the interstitial volume and pressure are constant. Parameters such as mean time-to-peak signal, overall fluorescence signal intensities, and number of active peristaltic pulses, were estimated from temporal imaging data. While the mean time to attain peak signal representative of diffusion-dominated flow in the lymph vessels was 0.6±0.2 min for MB and 8±6 min for IgG, showing a size dependence, the active propulsion rates were 3.4±0.8 pulses/min and 3.3±0.5 pulses/min, respectively, appearing size independent. The propulsion rates for both dyes decreased with clearance from the interstitial injection-site, indicating intrinsic control of the smooth muscles in response to interstitial pressure. This approach to size-comparative agent flow imaging of lymphatic function can enable noninvasive characterization of diseases related to uptake and flow in lymph networks.

Optimization of cell receptor-specific targeting through multivalent surface decoration of polymeric nanocarriers

PubMed Central

D’Addio, Suzanne M.; Baldassano, Steven; Shi, Lei; Cheung, Lila; Adamson, Douglas H.; Bruzek, Matthew; Anthony, John E.; Laskin, Debra L.; Sinko, Patrick J.; Prud’homme, Robert K.

2013-01-01

Treatment of tuberculosis is impaired by poor drug bioavailability, systemic side effects, patient non-compliance, and pathogen resistance to existing therapies. The mannose receptor (MR) is known to be involved in the recognition and internalization of Mycobacterium tuberculosis. We present a new assembly process to produce nanocarriers with variable surface densities of mannose targeting ligands in a single step, using kinetically-controlled, block copolymer-directed assembly. Nanocarrier association with murine macrophage J774 cells expressing the MR is examined as a function of incubation time and temperature, nanocarrier size, dose, and PEG corona properties. Amphiphilic diblock copolymers are prepared with terminal hydroxyl, methoxy, or mannoside functionality and incorporated into nanocarrier formulations at specific ratios by Flash NanoPrecipitation. Association of nanocarriers protected by a hydroxyl-terminated PEG corona with J774 cells is size dependent, while nanocarriers with methoxy-terminated PEG coronas do not associate with cells, regardless of size. Specific targeting of the MR is investigated using nanocarriers having 0-75% mannoside-terminated PEG chains in the PEG corona. This is a wider range of mannose densities than has been previously studied. Maximum nanocarrier association is attained with 9% mannoside-terminated PEG chains, increasing uptake more than 3-fold compared to non-targeted nanocarriers with a 5 kg mol−1 methoxy-terminated PEG corona. While a 5 kg mol−1 methoxy-terminated PEG corona prevents non-specific uptake, a 1.8 kg mol−1 methoxy-terminated PEG corona does not sufficiently protect the nanocarriers from nonspecific association. There is continuous uptake of MR-targeted nanocarriers at 37°C, but a saturation of association at 4°C. The majority of targeted nanocarriers associate with J774E cells are internalized at 37°C and uptake is receptor-dependent, diminishing with competitive inhibition by dextran. This characterization of nanocarrier uptake and targeting provides promise for optimizing drug delivery to macrophages for TB treatment and establishes a general route for optimizing targeted formulations of nanocarriers for specific delivery at targeted sites. PMID:23419950

Imipramine treatment differentially affects platelet /sup 3/H-imipramine binding and serotonin uptake in depressed patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suranyi-Cadotte, B.E.; Quirion, R.; Nair, N.P.V.

1985-02-25

Uptake of serotonin and /sup 3/H-imipramine binding in platelets of depressed patients were investigated simultaneously with changes in clinical state. Both V/sub max/ for serotonin uptake and B/sub max/ for /sup 3/H-imipramine binding were significantly lower in unmedicated depressed patients with respect to normal subjects. Successful treatment with imipramine led to a significant increase in B/sub max/ for /sup 3/H-imipramine binding, without significant change in V/sub max/ for serotonin uptake. B/sub max/ values increased to the normal range following complete, rather than partial clinical improvement. These data indicate that successful antidepressant treatment may increase the density of /sup 3/H-imipramine bindingmore » sites on platelets by a process which is independent of the uptake of serotonin. 29 references, 1 table.« less

Renal amyloidosis. Evaluation by gallium imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, V.W.; Skinner, M.; Cohen, A.S.

1986-09-01

A study has been performed to evaluate the efficacy of gallium imaging in the detection of renal amyloidosis. Ten of the 11 patients who had biopsy-proven renal amyloidosis demonstrated marked uptake in both kidneys. One patient revealed moderate gallium uptake in his kidneys. None of the patients had underlying renal or extrarenal pathology other than amyloidosis, which could account for renal gallium uptake (renal infection, neoplasm, hepatic failure or frequent blood transfusions). Four patients also had extrarenal foci of abnormal gallium uptake, suggesting other sites of amyloid deposits. Our data strongly suggest that gallium imaging has a high sensitivity formore » detection of renal amyloidosis. Its specificity is enhanced significantly by careful review of the clinical history to exclude other known causes of renal gallium uptake. Potentially, gallium imaging may be used to monitor the progress of patients under experimental therapy.« less

Quantifying substrate uptake by individual cells of marine bacterioplankton by catalyzed reporter deposition fluorescence in situ hybridization combined with microautoradiography.

PubMed

Sintes, Eva; Herndl, Gerhard J

2006-11-01

Catalyzed reporter deposition fluorescence in situ hybridization combined with microautoradiography (MICRO-CARD-FISH) is increasingly being used to obtain qualitative information on substrate uptake by individual members of specific prokaryotic communities. Here we evaluated the potential for using this approach quantitatively by relating the measured silver grain area around cells taking up (3)H-labeled leucine to bulk leucine uptake measurements. The increase in the silver grain area over time around leucine-assimilating cells of coastal bacterial assemblages was linear during 4 to 6 h of incubation. By establishing standardized conditions for specific activity levels and concomitantly performing uptake measurements with the bulk community, MICRO-CARD-FISH can be used quantitatively to determine uptake rates on a single-cell level. Therefore, this approach allows comparisons of single-cell activities for bacterial communities obtained from different sites or growing under different ecological conditions.

Quantifying Substrate Uptake by Individual Cells of Marine Bacterioplankton by Catalyzed Reporter Deposition Fluorescence In Situ Hybridization Combined with Microautoradiography▿

PubMed Central

Sintes, Eva; Herndl, Gerhard J.

2006-01-01

Catalyzed reporter deposition fluorescence in situ hybridization combined with microautoradiography (MICRO-CARD-FISH) is increasingly being used to obtain qualitative information on substrate uptake by individual members of specific prokaryotic communities. Here we evaluated the potential for using this approach quantitatively by relating the measured silver grain area around cells taking up 3H-labeled leucine to bulk leucine uptake measurements. The increase in the silver grain area over time around leucine-assimilating cells of coastal bacterial assemblages was linear during 4 to 6 h of incubation. By establishing standardized conditions for specific activity levels and concomitantly performing uptake measurements with the bulk community, MICRO-CARD-FISH can be used quantitatively to determine uptake rates on a single-cell level. Therefore, this approach allows comparisons of single-cell activities for bacterial communities obtained from different sites or growing under different ecological conditions. PMID:16950912

Pharmacology and expression analysis of glycine transporter GlyT1 with [3H]-(N-[3-(4'-fluorophenyl)-3-(4'phenylphenoxy)propyl])sarcosine.

PubMed

Mallorga, Pierre J; Williams, Jacinta B; Jacobson, Marlene; Marques, Rosemary; Chaudhary, Ashok; Conn, P Jeffrey; Pettibone, Douglas J; Sur, Cyrille

2003-10-01

In the central nervous system, re-uptake of the neurotransmitter glycine is mediated by two different glycine transporters, GlyT1 and GlyT2. GlyT2 is found in brainstem and spinal cord, whereas GlyT1 is expressed in rat forebrain regions where it is responsible for most glycine transport activity. Initially, GlyT1 and GlyT2 were pharmacologically differentiated by sarcosine, a weak selective inhibitor of GlyT1. The recently described selective and potent GlyT1 antagonist, NFPS/ALX-5407 provided an important additional tool to further characterize GlyT1 pharmacology. In the present study, we have radiolabeled the racemic form of NFPS (N-[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)propyl])sarcosine (also known as ALX-5407) to investigate its interaction with GlyT1, as well as define GlyT1 expression in the rat central nervous system. Kinetic studies indicated that [3H]NFPS binds rapidly to rat forebrain membranes and dissociates with a t(1/2) of 28 +/- 5 min. [3H]NFPS labeled a saturable population of sites in rat forebrain with a Kd of 7.1+/-1.3 nM and a B(max) of 3.14 +/- 0.26 pmol/mg protein. Bound [3H]NFPS was fully and potently displaced by unlabeled NFPS, whereas glycine and sarcosine were weak, Na+-dependent inhibitors with IC50 of 1,008 and 190 microM, respectively. Additional saturation experiments indicated that glycine and sarcosine were non-competitive antagonists of [3H]NFPS binding. Functional studies revealed that NFPS was a non-competitive inhibitor of [3H]glycine uptake and does not interact with Na+ and Cl- binding sites of GlyT1. Overall, this work shows that [3H]NFPS is a valuable tool in studying GlyT1 expression and pharmacology and that NFPS interacts with GlyT1 at a site different from the transporter translocation and ion binding sites.

Enzyme-Responsive Liposomes for the Delivery of Anticancer Drugs

PubMed Central

Fouladi, Farnaz; Steffen, Kristine J.; Mallik, Sanku

2017-01-01

Liposomes are nanocarriers that deliver the payloads at the target site, leading to therapeutic drug concentrations at the diseased site and reduced toxic effects in healthy tissues. Several approaches have been used to enhance the ability of the nanocarrier to target the specific tissues, including ligand-targeted liposomes and stimuli-responsive liposomes. Ligand-targeted liposomes exhibit higher uptake by the target tissue due to the targeting ligand attached to the surface, while, the stimuli-responsive liposomes do not release their cargo unless they expose to an endogenous or exogenous stimulant at the target site. In this review, we mainly focus on the liposomes that are responsive to pathologically increased levels of enzymes at the target site. Enzyme-responsive liposomes release their cargo upon contact with the enzyme through several destabilization mechanisms: a) structural perturbation in the lipid bilayer, b) removal of a shielding polymer from the surface and increased cellular uptake, c) cleavage of a lipopeptide or lipopolymer incorporated in the bilayer, and d) activation of a prodrug in the liposomes. PMID:28201868

Enzyme-Responsive Liposomes for the Delivery of Anticancer Drugs.

PubMed

Fouladi, Farnaz; Steffen, Kristine J; Mallik, Sanku

2017-04-19

Liposomes are nanocarriers that deliver the payloads at the target site, leading to therapeutic drug concentrations at the diseased site and reduced toxic effects in healthy tissues. Several approaches have been used to enhance the ability of the nanocarrier to target the specific tissues, including ligand-targeted liposomes and stimuli-responsive liposomes. Ligand-targeted liposomes exhibit higher uptake by the target tissue due to the targeting ligand attached to the surface, while the stimuli-responsive liposomes do not release their cargo unless they expose to an endogenous or exogenous stimulant at the target site. In this review, we mainly focus on the liposomes that are responsive to pathologically increased levels of enzymes at the target site. Enzyme-responsive liposomes release their cargo upon contact with the enzyme through several destabilization mechanisms: (1) structural perturbation in the lipid bilayer, (2) removal of a shielding polymer from the surface and increased cellular uptake, (3) cleavage of a lipopeptide or lipopolymer incorporated in the bilayer, and (4) activation of a prodrug in the liposomes.

A novel Online-to-Offline (O2O) model for pre-exposure prophylaxis and HIV testing scale up.

PubMed

Anand, Tarandeep; Nitpolprasert, Chattiya; Trachunthong, Deondara; Kerr, Stephen J; Janyam, Surang; Linjongrat, Danai; Hightow-Weidman, Lisa B; Phanuphak, Praphan; Ananworanich, Jintanat; Phanuphak, Nittaya

2017-03-13

PrEP awareness and uptake among men who have sex with men (MSM) and transgender women (TG) in Thailand remains low. Finding ways to increase HIV testing and PrEP uptake among high-risk groups is a critical priority. This study evaluates the effect of a novel Adam's Love Online-to-Offline (O2O) model on PrEP and HIV testing uptake among Thai MSM and TG and identifies factors associated with PrEP uptake. The O2O model was piloted by Adam's Love (www.adamslove.org) HIV educational and counselling website. MSM and TG reached online by PrEP promotions and interested in free PrEP and/or HIV testing services contacted Adam's Love online staff, received real-time PrEP eCounseling, and completed online bookings for receiving services at one of the four sites in Bangkok based on their preference. Auto-generated site- and service-specific e-tickets and Quick Response (QR) codes were sent to their mobile devices enabling monitoring and check-in by offline site staff. Service uptake and participant's socio-demographic and risk behaviour characteristics were analyzed. Factors associated with PrEP uptake were assessed using multiple logistic regression. Between January 10th and April 11th, 2016, Adam's Love reached 272,568 people online via the PrEP O2O promotions. 425 MSM and TG received eCounseling and e-tickets. There were 325 (76.5%) MSM and TG who checked-in at clinics and received HIV testing. Nine (2.8%) were diagnosed with HIV infection. Median (IQR) time between receiving the e-ticket and checking-in was 3 (0-7) days. Of 316 HIV-negative MSM and TG, 168 (53.2%) started PrEP. In a multivariate model, higher education (OR 2.30, 95%CI 1.14-4.66; p  = 0.02), seeking sex partners online (OR 2.05, 95%CI 1.19-3.54; p  = 0.009), being aware of sexual partners' HIV status (OR 2.37, 95%CI 1.29-4.35; p  = 0.008), ever previously using post-exposure prophylaxis (PEP) (OR 2.46, 95%CI 1.19-5.09; p  = 0.01), and enrolment at Adam's Love clinic compared to the other three sites (OR 3.79, 95%CI 2.06-6.95; p  < 0.001) were independently associated with PrEP uptake. Adam's Love O2O model is highly effective in linking online at-risk MSM and TG to PrEP and HIV testing services, and has high potential to be replicated and scaled up in other settings with high Internet penetration among key populations.

Negatively Cooperative Binding of High Density Lipoprotein to the HDL Receptor SR-BI†

PubMed Central

Nieland, Thomas J.F.; Xu, Shangzhe; Penman, Marsha; Krieger, Monty

2011-01-01

Scavenger receptor class B, type I (SR-BI) is a high-density lipoprotein (HDL) receptor, which also binds low density lipoprotein (LDL), and mediates the cellular selective uptake of cholesteryl esters from lipoproteins. SR-BI also is a co-receptor for hepatitis C virus and a signaling receptor that regulates cell metabolism. Many investigators have reported that lipoproteins bind to SR-BI via a single class of independent (not interacting), high affinity binding sites (one site model). We have re-investigated the ligand concentration dependence of 125I-HDL binding to SR-BI and SR-BI-mediated specific uptake of [3H]CE from [3H]CE-HDL using an expanded range of ligand concentrations (<1 µg protein/ml, lower than previously reported). Scatchard and non-linear least squares model fitting analyses of the binding and uptake data were both inconsistent with a single class of independent binding sites binding univalent lipoprotein ligands. The data are best fit by models in which SR-BI has either two independent classes of binding sites, or one class of sites exhibiting negative cooperativity due to either classic allostery or ensemble effects (‘ lattice model’). Similar results were observed for LDL. Application of the ‘infinite dilution’ dissociation rate method established that the binding of 125I-HDL to SR-BI at 4 °C exhibits negative cooperativity. The unexpected complexity of the interactions of lipoproteins with SR-BI should be taken into account when interpreting the results of experiments that explore the mechanism(s) by which SR-BI mediates ligand binding, lipid transport and cell signaling. PMID:21254782

Fire effects on the mobilization and uptake of nitrogen by cheatgrass (Bromus tectorum L.)

Treesearch

Brittany G. Johnson; Dale W. Johnson; Jeanne C. Chambers; Robert R. Blank

2011-01-01

Cheatgrass (Bromus tectorum L.), an invasive annual grass, is displacing native species and causing increased fire frequency in the Great Basin of the southwestern United States. Growth and nitrogen uptake patterns by cheatgrass were examined in a greenhouse study using soils from sites with the same soil type but different fire histories: 1) an area that burned in...

Characterization of the selenite uptake mechanism in the coccolithophore Emiliania huxleyi (Haptophyta).

PubMed

Araie, Hiroya; Sakamoto, Kou; Suzuki, Iwane; Shiraiwa, Yoshihiro

2011-07-01

The marine coccolithophore Emiliania huxleyi (Haptophyta) requires selenium as an essential element for growth, and the active species absorbed is selenite, not selenate. This study characterized the selenite uptake mechanism using ⁷⁵Se as a tracer. Kinetic analysis of selenite uptake showed the involvement of both active and passive transport processes. The active transport was suppressed by 0.5 mM vanadate, a membrane-permeable inhibitor of H⁺-ATPase, at pH 8.3. When the pH was lowered from 8.3 to 5.3, the selenite uptake activity greatly increased, even in the presence of vanadate, suggesting that the H⁺ concentration gradient may be a motive force for selenite transport. [⁷⁵Se]Selenite uptake at selenite-limiting concentrations was hardly affected by selenate, sulfate and sulfite, even at 100 μM. In contrast, 3 μM orthophosphate increased the K(m) 5-fold. These data showed that HSeO₃⁻, a dominant selenite species at acidic pH, is the active species for transport through the plasma membrane and transport is driven by ΔpH energized by H⁺-ATPase. Kinetic analysis showed that the selenite uptake activity was competitively inhibited by orthophosphate. Furthermore, the active selenite transport mechanism was shown to be induced de novo under Se-deficient conditions and induction was suppressed by the addition of either sufficient selenite or cycloheximide, an inhibitor of de novo protein synthesis. These results indicate that E. huxleyi cells developed an active selenite uptake mechanism to overcome the disadvantages of Se limitation in ecosystems, maintaining selenium metabolism and selenoproteins for high viability.

Regional glucose utilization in infarcted and remote myocardium: its relation to coronary anatomy and perfusion.

PubMed

Fragasso, G; Chierchia, S L; Landoni, C; Lucignani, G; Rossetti, E; Sciammarella, M; Vanoli, G E; Fazio, F

1998-07-01

We studied the relationship between coronary anatomy, perfusion and metabolism in myocardial segments exhibiting transient and persistent perfusion defects on stress/rest 99Tcm-MIBI single photon emission tomography in 35 patients (31 males, 4 females, mean age 56 +/- 7 years) with a previous myocardial infarction. Quantitative coronary angiography and assessment of myocardial perfusion reserve and glucose metabolism were performed within 1 week of one another. Perfusion was assessed by SPET after the intravenous injection of 740 MBq of 99Tcm-MIBI at rest and after exercise. Regional myocardial glucose metabolism was assessed by position emission tomography at rest (200 MBq of 18F-2-deoxyglucose, FDG) after an overnight fast with no glucose loading. All 35 patients exhibited persistent perfusion defects consistent with the clinically identified infarct site, and 27 (77%) also showed various degrees of within-infarct FDG uptake; 11 patients developed exercise-induced transient perfusion defects within, or in the vicinity of, 15 infarct segments and resting FDG uptake was present in 10 of these segments (67%). Five patients also showed exercise-induced transient perfusion defects in nine segments remote from the site of infarct: resting FDG uptake was present in six of these regions (67%). Finally, nine patients had increased glucose uptake in non-infarcted regions not showing transient perfusion defects upon exercise testing and perfused by coronary arteries with only minor irregularities. Our results confirm the presence of viable tissue in a large proportion of infarct sites. Moreover, FDG uptake can be seen in regions perfused by coronary arteries showing minor irregularities, not necessarily resulting in detectable transient perfusion defects on a MIBI stress scan. Since the clinical significance of such findings is not clear, further studies should be conducted to assess the long-term evolution of perfusion, function and metabolism in non-revascularized patients of those remote areas which are apparently normally perfused, but show abnormal fasting FDG uptake after myocardial infarction. Such studies may have important implications for the management of post-infarct patients, as the preservation of coronary vasodilator reserve and myocardial metabolism in remote myocardium may be seen as an additional goal in the treatment of such patients.

Characterizing the Solid-Solution Coefficient and Plant Uptake Factor of As, Cd and Pb in California Croplands

USDA-ARS?s Scientific Manuscript database

In risk assessment models, the solid-solution partition coefficient (Kd), and plant uptake factor (PUF), are often employed to model the fate and transport of trace elements in soils. The trustworthiness of risk assessments depends on the reliability of the parameters used. In this study, we exami...

Implementing effective policy in a national mental health re-engagement program for Veterans

PubMed Central

Smith, Shawna N.; Lai, Zongshan; Almirall, Daniel; Goodrich, David E.; Abraham, Kristen M.; Nord, Kristina M.; Kilbourne, Amy M.

2016-01-01

Policy is a powerful motivator of clinical change, but implementation success can depend on organizational characteristics. This paper used validated measures of organizational resources, culture and climate to predict uptake of a nationwide VA policy aimed at implementing Re-Engage, a brief care management program that re-establishes contact with Veterans with serious mental illness lost to care. Patient care databases were used to identify 2,738 Veterans lost to care. Local Recovery Coordinators (LRCs) were to update disposition for 2,738 Veterans at 158 VA facilities and, as appropriate, facilitate a return to care. Multivariable regression assessed organizational culture and climate as predictors of early policy compliance (via LRC presence) and uptake at six months. Higher composite climate and culture scores were associated with higher odds of having a designated LRC, but were not predictive of higher uptake. Sites with LRCs had significantly higher rates of updated documentation than sites without LRCs. PMID:27668352

Barrier dysfunction and bacterial uptake in the follicle-associated epithelium of ileal Crohn's disease.

PubMed

Keita, Asa V; Söderholm, Johan D

2012-07-01

The ability to control uptake across the mucosa and protect from harmful substances in the gut lumen is defined as intestinal barrier function. The etiology of Crohn's disease is unknown, but genetic, environmental, and immunological factors all contribute. The frontline between these factors lies in the intestinal barrier. The most important inflammation-driving environmental factor in Crohn's disease is the microbiota, where Esherichia coli strains have been assigned a key role. The first observable signs of Crohn's disease are small aphtoid ulcers over Peyer's patches and lymphoid follicles. The overlaying follicle-associated epithelium (FAE) is specialized for luminal sampling and is an entry site for antigens and bacteria. We have demonstrated increased E. coli uptake across the FAE in Crohn's disease, which may initiate inflammation. This short review will discuss barrier dysfunction and bacteria in the context of ileal Crohn's disease, and how the FAE might be the site of initial inflammation. © 2012 New York Academy of Sciences.

Value of 18F-3,4-dihydroxyphenylalanine PET/MR image fusion in pediatric supratentorial infiltrative astrocytomas: a prospective pilot study.

PubMed

Morana, Giovanni; Piccardo, Arnoldo; Milanaccio, Claudia; Puntoni, Matteo; Nozza, Paolo; Cama, Armando; Zefiro, Daniele; Cabria, Massimo; Rossi, Andrea; Garrè, Maria Luisa

2014-05-01

Infiltrative astrocytomas (IAs) represent a group of astrocytic gliomas ranging from low-grade to highly malignant, characterized by diffuse invasion of the brain parenchyma. When compared with their adult counterpart, pediatric IAs may be considered biologically distinct entities; nevertheless, similarly to those in adults they represent a complex oncologic challenge. The aim of this study was to investigate the diagnostic role, clinical contribution, and prognostic value of fused (18)F-3,4-dihydroxyphenylalanine ((18)F-DOPA) PET/MR images in pediatric supratentorial IAs. Pediatric patients with supratentorial IAs involving at least 2 cerebral lobes, either newly diagnosed or with suspected disease progression, prospectively underwent (18)F-DOPA PET and conventional MR imaging, performed within 10 d of each other. (18)F-DOPA PET data were interpreted qualitatively and semiquantitatively, fusing images with MR images. PET scans were classified as positive if tumors identified on MR imaging exhibited tracer uptake above the level of the corresponding contralateral normal brain. Maximum standardized uptake values, tumor-to-normal contralateral tissue ratios, and tumor-to-normal striatum ratios were calculated for all tumors. Correlations between the degree and extent of (18)F-DOPA uptake, MR imaging tumor characteristics, and histologic results were investigated. The contribution of (18)F-DOPA PET/MR image fusion was considered relevant if it enabled one to select the most appropriate biopsy site, discriminate between disease progression and treatment-related changes, or influence treatment strategy. The patient's outcome was finally correlated with (18)F-DOPA uptake. Thirteen patients (8 boys and 5 girls) were included (5 diffuse astrocytomas, 2 anaplastic astrocytomas, 5 gliomatosis cerebri, and 1 glioblastoma multiforme). The (18)F-DOPA uptake pattern was heterogeneous in all positive scans (9/13), revealing metabolic heterogeneities within each tumor. Significant differences in terms of (18)F-DOPA uptake were found between low- and high-grade lesions (P < 0.05). The diagnostic and therapeutic contribution of (18)F-DOPA PET/MR image fusion was relevant in 9 of 13 patients (69%). (18)F-DOPA uptake correlated significantly with progression-free survival (P = 0.004). Our results indicate that (18)F-DOPA PET/MR image fusion may be a reliable imaging biomarker of pediatric IAs. Information gathered by this combined imaging approach can be readily transferred to the everyday practice and may help clinicians to better stratify patients with IAs, especially diffuse astrocytomas and gliomatosis cerebri, for diagnostic, therapeutic, and prognostic purposes.

Rising atmospheric CO2 leads to large impact of biology on Southern Ocean CO2 uptake via changes of the Revelle factor

PubMed Central

Hauck, J; Völker, C

2015-01-01

The Southern Ocean is a key region for global carbon uptake and is characterized by a strong seasonality with the annual CO2 uptake being mediated by biological carbon drawdown in summer. Here we show that the contribution of biology to CO2 uptake will become even more important until 2100. This is the case even if biological production remains unaltered and can be explained by the decreasing buffer capacity of the ocean as its carbon content increases. The same amount of biological carbon drawdown leads to a more than twice as large reduction in CO2(aq) concentration and hence to a larger CO2 gradient between ocean and atmosphere that drives the gas exchange. While the winter uptake south of 44°S changes little, the summer uptake increases largely and is responsible for the annual mean response. The combination of decreasing buffer capacity and strong seasonality of biological carbon drawdown introduces a strong and increasing seasonality in the anthropogenic carbon uptake. Key Points Decrease of buffer capacity leads to stronger summer CO2 uptake in the future Biology will contribute more to future CO2 uptake in Southern Ocean Seasonality affects anthropogenic carbon uptake strongly PMID:26074650

Novel Therapeutic Targets to Treat Social Behavior Deficits in Autism and Related Disorders

DTIC Science & Technology

2014-10-01

2a. Effects of D- 22 on [3H] serotonin uptake in vitro We have made good progress toward characterizing D- 22 ’s ability to block serotonin (5- HT ...b. Fig 4. [3H] 5- HT Synaptosomal Uptake Blockade by D- 22 and Fluoxetine. D- 22 is effective in vitro at µM concentrations...c. In vivo chronoamperometry to measure the effect of D- 22 on 5- HT uptake In BTBR mice, the effects of systemic (i.p.) injection of D- 22 on in vivo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Despotopulos, John D.; Kmak, Kelly N.; Gharibyan, Narek

Eichrom’s Pb resin, a crown-ether-based extraction chromatography resin, was characterized for separation of the flerovium (Fl) homologs, Pb and Sn. Batch uptake of Pb(II) and Sn(IV) radionuclides was determined from an HNO 3 matrix. Pb(II) was strongly retained on the resin at all HNO 3 concentrations, while Sn(IV) showed no uptake. Extraction kinetics for Pb(II) were examined and show suitable uptake on the second time scale. Here, separation methods for the isolation of individual homologs, Pb(II) and Sn(IV), have been established using 2 mL pre-packed vacuum flow Pb resin columns.

Nuclear uptake of an amino-terminal fragment of apolipoprotein E4 promotes cell death and localizes within microglia of the Alzheimer's disease brain.

PubMed

Love, Julia E; Day, Ryan J; Gause, Justin W; Brown, Raquel J; Pu, Xinzhu; Theis, Dustin I; Caraway, Chad A; Poon, Wayne W; Rahman, Abir A; Morrison, Brad E; Rohn, Troy T

2017-01-01

Although harboring the apolipoprotein E4 ( APOE4 ) allele is a well known risk factor in Alzheimer's disease (AD), the mechanism by which it contributes to disease risk remains elusive. To investigate the role of proteolysis of apoE4 as a potential mechanism, we designed and characterized a site-directed cleavage antibody directed at position D151 of the mature form of apoE4 and E3. Characterization of this antibody indicated a high specificity for detecting synthesized recombinant proteins corresponding to the amino acid sequences 1-151 of apoE3 and E4 that would generate the 17 kDa (p17) fragment. In addition, this antibody also detected a ~17 kDa amino-terminal fragment of apoE4 following incubation with collagenase and matrix metalloproteinase-9 (MMP-9), but did not react with full-length apoE4. Application of this amino-terminal apoE cleavage-fragment (nApoECFp17) antibody, revealed nuclear labeling within glial cells and labeling of a subset of neurofibrillary tangles in the human AD brain. A quantitative analysis indicated that roughly 80% of labeled nuclei were microglia. To confirm these findings, cultured BV2 microglia cells were incubated with the amino-terminal fragment of apoE4 corresponding to the cleavage site at D151. The results indicated efficient uptake of this fragment and trafficking to the nucleus that also resulted in significant cell death. In contrast, a similarly designed apoE3 fragment showed no toxicity and primarily localized within the cytoplasm. These data suggest a novel cleavage event by which apoE4 is cleaved by the extracellular proteases, collagenase and MMP-9, generating an amino-terminal fragment that is then taken up by microglia, traffics to the nucleus and promotes cell death. Collectively, these findings provide important mechanistic insights into the mechanism by which harboring the APOE4 allele may elevate dementia risk observed in AD.

Analysis of chorioallantoic membranes to assess PCB accumulation in American alligators and Loggerhead sea turtles from the coast of South Carolina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cobb, G.P.; Wood, P.D.; O`Quinn, M.

1995-12-31

Investigation of contaminant burdens in threatened and endangered species is difficult due to the small number of samples that can be collected. Many samples can be collected if the sampling methods are non-lethal and more specifically non-invasive. Analysis of chorioallantoic membranes is demonstrated for American alligators and Loggerhead sea turtles. Significant differences were found in PCB, uptake by alligators from the Ashepoo-Combahee-Edisto Basin reference site and a contaminated site in Winyah Bay. Intrasite and intersite differences in uptake and distribution of PCB homologues were noted. These data will be discussed as they relate to egg viability and embryo development.

A chemical equilibrium model for metal adsorption onto bacterial surfaces

NASA Astrophysics Data System (ADS)

Fein, Jeremy B.; Daughney, Christopher J.; Yee, Nathan; Davis, Thomas A.

1997-08-01

This study quantifies metal adsorption onto cell wall surfaces of Bacillus subtilis by applying equilibrium thermodynamics to the specific chemical reactions that occur at the water-bacteria interface. We use acid/base titrations to determine deprotonation constants for the important surface functional groups, and we perform metal-bacteria adsorption experiments, using Cd, Cu, Pb, and Al, to yield site-specific stability constants for the important metal-bacteria surface complexes. The acid/base properties of the cell wall of B. subtilis can best be characterized by invoking three distinct types of surface organic acid functional groups, with pK a values of 4.82 ± 0.14, 6.9 ± 0.5, and 9.4 ± 0.6. These functional groups likely correspond to carboxyl, phosphate, and hydroxyl sites, respectively, that are displayed on the cell wall surface. The results of the metal adsorption experiments indicate that both the carboxyl sites and the phosphate sites contribute to metal uptake. The values of the log stability constants for metal-carboxyl surface complexes range from 3.4 for Cd, 4.2 for Pb, 4.3 for Cu, to 5.0 for Al. These results suggest that the stabilities of the metal-surface complexes are high enough for metal-bacterial interactions to affect metal mobilities in many aqueous systems, and this approach enables quantitative assessment of the effects of bacteria on metal mobilities.

First Case of the Cervical Lymph Node as the Only Site of Metastasis from Anal Cancer.

PubMed

Wang, Bo; Jaiswal, Sunny; Saif, Muhammad W

2017-05-30

Anal squamous cell carcinoma was a previously uncommon malignancy that has steadily increased in incidence with the increased prevalence of human papillomavirus (HPV) and human immunodeficiency virus (HIV). Anal squamous cell carcinoma is typically characterized by local and regional involvement and distant metastases are far less common. Here, we report a case of a 36-year-old female initially diagnosed with anal squamous cell carcinoma manifesting as an anal mass along with an enlarged inguinal lymph node. After receiving chemoradiation therapy, she remained disease-free until recently, when she presented with an isolated left infraclavicular lymph node found on physical examination followed by a biopsy that was consistent with recurrent anal squamous cell carcinoma. The positron emission tomography-computed tomography (PET-CT) uptake of her original left inguinal lymph node was decreased, suggesting improved regional disease, and no other metastases were found. Our case represents a rare occurrence of metastatic anal squamous cell carcinoma to an isolated distal lymph node and reminds physicians not to forget a unusual site of metastasis and prevent any delay in treatment.

Moisture sorption by cellulose powders of varying crystallinity.

PubMed

Mihranyan, Albert; Llagostera, Assumpcio Piñas; Karmhag, Richard; Strømme, Maria; Ek, Ragnar

2004-01-28

Moisture in microcrystalline cellulose may cause stability problems for moisture sensitive drugs. The aim of this study was to investigate the influence of crystallinity and surface area on the uptake of moisture in cellulose powders. Powders of varying crystallinity were manufactured, and the uptake of moisture was investigated at different relative humidities. The structure of the cellulose powders was characterized by X-ray diffraction, BET surface area analysis, and scanning electron microscopy. Moisture uptake was directly related to the cellulose crystallinity and pore volume: Cellulose powders with higher crystallinity showed lower moisture uptake at relative humidities below 75%, while at higher humidities the moisture uptake could be associated with filling of the large pore volume of the cellulose powder of highest crystallinity. In conclusion, the structure of cellulose should be thoroughly considered when manufacturing low moisture grades of MCC.

Accumulation of Ag and Cu in Amanita strobiliformis and characterization of its Cu and Ag uptake transporter genes AsCTR2 and AsCTR3.

PubMed

Beneš, Vojtěch; Hložková, Kateřina; Matěnová, Michaela; Borovička, Jan; Kotrba, Pavel

2016-04-01

Macrofungi can accumulate in their sporocarps remarkably high concentrations of Cu and Ag. We have previously demonstrated that the non-essential Ag is in the ectomycorrhizal, Ag-hyperaccumulating Amanita strobiliformis sequestered by 3.4-kDa metallothioneins (MTs) produced as AsMT1a, 1b and 1c isoforms. Here, we describe two populations of wild-grown A. strobiliformis sporocarps, which showed certain correlation between the concentrations of accumulated Ag (284 ± 64 and 67 ± 15 mg kg(-1)) and Cu (76 ± 13 and 30 ± 12 mg kg(-1)), suggesting that an overlap may exist in the cell biology of Ag and Cu in this species. Metal speciation analysis revealed that the intracellular Cu in the sporocarps of both populations was, like Ag, associated with the 3.4-kDa MTs. A search of A. strobiliformis transcriptome for sequences encoding proteins of the Cu transporter (CTR) family identified four AsCTR cDNAs, which were, like AsMT1s, confirmed in both populations. The predicted AsCTR proteins showed homology to vacuolar (AsCTR1 and AsCTR4) and plasma membrane (AsCTR2 and AsCTR3) CTRs. Heterologous expression of AsCTR2, AsCTR3 and their translational fusions with green fluorescent protein (GFP) in Cu uptake-deficient S. cerevisiae indicated that both AsCTRs are functional Cu and Ag uptake transporters: recombinant genes complemented growth defects and increased Cu and Ag uptake rates in yeasts and the GFP-tagged protein localized to the cell periphery. Site directed mutagenesis revealed the importance of the conserved-among-CTRs M-X3-M motif for the AsCTR2- and AsCTR3-mediated transport of both Cu and Ag. These results provide the first evidence that fungal CTRs can recognize Ag for transport.

Synthesis and in vitro biochemical evaluation of oxime bond-linked daunorubicin–GnRH-III conjugates developed for targeted drug delivery

PubMed Central

Schuster, Sabine; Biri-Kovács, Beáta; Szeder, Bálint; Farkas, Viktor; Buday, László; Szabó, Zsuzsanna; Halmos, Gábor

2018-01-01

Gonadotropin releasing hormone-III (GnRH-III), a native isoform of the human GnRH isolated from sea lamprey, specifically binds to GnRH receptors on cancer cells enabling its application as targeting moieties for anticancer drugs. Recently, we reported on the identification of a novel daunorubicin–GnRH-III conjugate (GnRH-III–[4Lys(Bu), 8Lys(Dau=Aoa)] with efficient in vitro and in vivo antitumor activity. To get a deeper insight into the mechanism of action of our lead compound, the cellular uptake was followed by confocal laser scanning microscopy. Hereby, the drug daunorubicin could be visualized in different subcellular compartments by following the localization of the drug in a time-dependent manner. Colocalization studies were carried out to prove the presence of the drug in lysosomes (early stage) and on its site of action (nuclei after 10 min). Additional flow cytometry studies demonstrated that the cellular uptake of the bioconjugate was inhibited in the presence of the competitive ligand triptorelin indicating a receptor-mediated pathway. For comparative purpose, six novel daunorubicin–GnRH-III bioconjugates have been synthesized and biochemically characterized in which 6Asp was replaced by D-Asp, D-Glu and D-Trp. In addition to the analysis of the in vitro cytostatic effect and cellular uptake, receptor binding studies with 125I-triptorelin as radiotracer and degradation of the GnRH-III conjugates in the presence of rat liver lysosomal homogenate have been performed. All derivatives showed high binding affinities to GnRH receptors and displayed in vitro cytostatic effects on HT-29 and MCF-7 cancer cells with IC50 values in a low micromolar range. Moreover, we found that the release of the active drug metabolite and the cellular uptake of the bioconjugates were strongly affected by the amino acid exchange which in turn had an impact on the antitumor activity of the bioconjugates. PMID:29719573

Polyamine Uptake in Carrot Cell Cultures 1

PubMed Central

Pistocchi, Rossella; Bagni, Nello; Creus, José A.

1987-01-01

Putrescine and spermidine uptake into carrot (Daucus carota L.) cells in culture was studied. The time course of uptake showed that the two polyamines were very quickly transported into the cells, reaching a maximum absorption within 1 minute. Increasing external polyamine concentrations up to 100 millimolar showed the existence of a biphasic system with different affinities at low and high polyamine concentrations. The cellular localization of absorbed polyamines was such that a greater amount of putrescine was present in the cytoplasmic soluble fraction, while spermidine was mostly present in cell walls. The absorbed polyamines were released into the medium in the presence of increasing external concentrations of the corresponding polyamine or Ca2+. The effects of Ca2+ were different for putrescine and spermidine; putrescine uptake was slightly stimulated by 10 micromolar Ca2+ and inhibited by higher concentrations, while for spermidine uptake there was an increasing stimulation in the Ca2+ concentration range between 10 micromolar and 1 millimolar. La3+ nullified the stimulatory effect of 10 micromolar Ca2+ on putrescine uptake and that of 1 millimolar Ca2+ on spermidine uptake. La3+ at 0.5 to 1 millimolar markedly inhibited the uptake of both polyamines, suggesting that it interferes with the sites of polyamine uptake. Putrescine uptake was affected to a lesser extent by metabolic inhibitors than was spermidine uptake. It is proposed that the entry of polyamines into the cells is driven by the transmembrane electrical gradient, with a possible antiport mechanism between external and internal polyamine molecule. PMID:16665446

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corley, Richard A.; Kabilan, Senthil; Kuprat, Andrew P.

Coupling computational fluid dynamics (CFD) with physiologically based pharmacokinetic (PBPK) models is useful for predicting site-specific dosimetry of airborne materials in the respiratory tract and elucidating the importance of species differences in anatomy, physiology, and breathing patterns. Historically, these models were limited to discrete regions of the respiratory system. CFD/PBPK models have now been developed for the rat, monkey, and human that encompass airways from the nose or mouth to the lung. A PBPK model previously developed to describe acrolein uptake in nasal tissues was adapted to the extended airway models as an example application. Model parameters for each anatomicmore » region were obtained from the literature, measured directly, or estimated from published data. Airflow and site-specific acrolein uptake patterns were determined under steadystate inhalation conditions to provide direct comparisons with prior data and nasalonly simulations. Results confirmed that regional uptake was dependent upon airflow rates and acrolein concentrations with nasal extraction efficiencies predicted to be greatest in the rat, followed by the monkey, then the human. For human oral-breathing simulations, acrolein uptake rates in oropharyngeal and laryngeal tissues were comparable to nasal tissues following nasal breathing under the same exposure conditions. For both breathing modes, higher uptake rates were predicted for lower tracheo-bronchial tissues of humans than either the rat or monkey. These extended airway models provide a unique foundation for comparing dosimetry across a significantly more extensive range of conducting airways in the rat, monkey, and human than prior CFD models.« less

Moss bags as sentinels for human safety in mercury-polluted groundwaters.

PubMed

Cesa, Mattia; Nimis, Pier Luigi; Buora, Clara; Lorenzonetto, Alberta; Pozzobon, Alessandro; Raris, Marina; Rosa, Maria; Salvadori, Michela

2014-05-01

An equation to estimate Hg concentrations of <4 μg/L in groundwaters of a polluted area in NE Italy was set out by using transplants of the aquatic moss Rhynchostegium riparioides as trace element bioaccumulators. The equation is derived from a previous mathematical model which was implemented under laboratory conditions. The work aimed at (1) checking the compliance of the uptake kinetics with the model, (2) improving/adapting the model for groundwater monitoring, (3) comparing the performances of two populations of moss collected from different sites, and (4) assessing the environmental impact of Hg contamination on a small river. The main factors affecting Hg uptake in the field were-as expected-water concentration and time of exposure, even though the uptake kinetics in the field were slightly different from those which were previously observed in the lab, since the redox environmental conditions influence the solubility of cationic Fe, which is a negative competitor of Hg(2+). The equation was improved by including the variable 'dissolved oxygen concentration'. A numerical parameter depending on the moss collection site was also provided, since the differences in uptake efficiency were observed between the two populations tested. Predicted Hg concentrations well fitted the values measured in situ (approximately ±50%), while a notable underestimation was observed when the equation was used to predict Hg concentration in a neighbouring river (-96%), probably due to the organic pollution which hampers metal uptake by mosses.

Knowledge, attitude, and uptake related to human papillomavirus vaccination among young women in Germany recruited via a social media site.

PubMed

Remschmidt, Cornelius; Walter, Dietmar; Schmich, Patrick; Wetzstein, Matthias; Deleré, Yvonne; Wichmann, Ole

2014-01-01

Many industrialized countries have introduced human papillomavirus (HPV) vaccination of young women, but vaccine uptake often remains suboptimal. This study aimed to investigate whether a social media site like Facebook is an appropriate tool to assess knowledge, attitude and uptake related to HPV vaccination in young women in Germany. Between December 2012 and January 2013 two different targeting strategies were implemented on Facebook, providing a link to an online questionnaire. Advertisements were displayed to female Facebook users aged 18-25 years living in Germany. During the simple targeting strategy, advertisements comprised health-related images along with various short titles and text messages. During the focused strategy, advertisements were targeted to users who in addition had certain fashion brands or pop stars listed on their profiles. The targeting strategies were compared with respect to participant characteristics. Univariate and multivariate analyses were used to identify factors associated with HPV vaccine uptake. A total of 1161 women participated. The two targeting strategies resulted in significant differences regarding educational status and migrant background. Overall, awareness of HPV was high, but only 53% received at least one vaccine dose. In multivariate analysis, HPV vaccine uptake was independently associated with a physician's recommendation and trust in vaccine effectiveness. Concerns of adverse effects were negatively associated with vaccine uptake. Social network recruitment permits fast and convenient access to young people. Sample characteristics can be manipulated by adjusting targeting strategies. There is further need for promoting knowledge of HPV vaccination among young women. Physicians have a major role in the vaccination decision-making process of young women.

Knowledge, attitude, and uptake related to human papillomavirus vaccination among young women in Germany recruited via a social media site

PubMed Central

Remschmidt, Cornelius; Walter, Dietmar; Schmich, Patrick; Wetzstein, Matthias; Deleré, Yvonne; Wichmann, Ole

2014-01-01

Background: Many industrialized countries have introduced human papillomavirus (HPV) vaccination of young women, but vaccine uptake often remains suboptimal. This study aimed to investigate whether a social media site like Facebook is an appropriate tool to assess knowledge, attitude and uptake related to HPV vaccination in young women in Germany. Methods: Between December 2012 and January 2013 two different targeting strategies were implemented on Facebook, providing a link to an online questionnaire. Advertisements were displayed to female Facebook users aged 18–25 years living in Germany. During the simple targeting strategy, advertisements comprised health-related images along with various short titles and text messages. During the focused strategy, advertisements were targeted to users who in addition had certain fashion brands or pop stars listed on their profiles. The targeting strategies were compared with respect to participant characteristics. Univariate and multivariate analyses were used to identify factors associated with HPV vaccine uptake. Results: A total of 1161 women participated. The two targeting strategies resulted in significant differences regarding educational status and migrant background. Overall, awareness of HPV was high, but only 53% received at least one vaccine dose. In multivariate analysis, HPV vaccine uptake was independently associated with a physician's recommendation and trust in vaccine effectiveness. Concerns of adverse effects were negatively associated with vaccine uptake. Discussion: Social network recruitment permits fast and convenient access to young people. Sample characteristics can be manipulated by adjusting targeting strategies. There is further need for promoting knowledge of HPV vaccination among young women. Physicians have a major role in the vaccination decision-making process of young women. PMID:25483492

Characteristics of competitive uptake between Microcystin-LR and natural organic matter (NOM) fractions using strongly basic anion exchange resins.

PubMed

Dixit, Fuhar; Barbeau, Benoit; Mohseni, Madjid

2018-08-01

Microcystins are the most commonly occurring cyanotoxins, and have been extensively studied across the globe. In the present study, a strongly basic anion exchange resin was employed to investigate the removal of Microcystin-LR (MCLR), one of the most toxic microcystin variants. Factors influencing the uptake behavior included the MCLR and resin concentrations, resin dosage, and natural organic matter (NOM) characteristics, specifically, the charge density and molecular weight distribution of source water NOM. Equivalent background concentration (EBC) was employed to evaluate the competitive uptake between NOM and MCLR. The experimental data were compared with different mathematical and physical models and pore diffusion was determined as the rate-limiting step. The resin dose/solute concentration ratio played a key role in the MCLR uptake process and MCLR removal was attributed primarily to electrostatic attractions. Charge density and molecular weight distribution of the background NOM fractions played a major role in MCLR removal at lower resin dosages (200 mg/L ∼ 1 mL/L and below), where a competitive uptake was observed due to the limited exchange sites. Further, evidences of pore blockage and site reduction were also observed in the presence of humics and larger molecular weight organic fractions, where a four-fold reduction in the MCLR uptake was observed. Comparable results were obtained for laboratory studies on synthetic laboratory water and surface water under similar conditions. Given their excellent performance and low cost, anion exchange resins are expected to present promising potentials for applications involving the removal of removal of algal toxins and NOM from surface waters. Copyright © 2018 Elsevier Ltd. All rights reserved.

Pharmacological evaluation of [123I]-CLINDE: a radioiodinated imidazopyridine-3-acetamide for the study of peripheral benzodiazepine binding sites (PBBS).

PubMed

Mattner, Filomena; Mardon, Karine; Katsifis, Andrew

2008-04-01

The study aims to evaluate the iodinated imidazopyridine, N',N'-diethyl-6-Chloro-(4'-[(123)I]iodophenyl)imidazo[1,2-a]pyridine-3-acetamide ([(123)I]-CLINDE) as a tracer for the study of peripheral benzodiazepine binding sites (PBBS). In vitro studies were performed using membrane homogenates and sections from kidney, adrenals, and brain cortex of Sprague-Dawley (SD) rats and incubated with [(123)I]-CLINDE. For in vivo studies, the rats were injected with [(123)I]-CLINDE. In competition studies, PBBS-specific drugs PK11195 and Ro 5-4864 and the CBR specific drug Flumazenil were injected before the radiotracer. In vitro binding studies in adrenal, kidney, and cortex mitochondrial membranes indicated that [(123)I]-CLINDE binds with high affinity to PBBS, K(d) = 12.6, 0.20, and 3.84 nM, respectively. The density of binding sites was 163, 5.3, and 0.34 pmol/mg protein, respectively. In vivo biodistribution indicated high uptake in adrenals (5.4), heart (1.5), lungs (1.5), kidney (1.5) %ID/g at 6 h p.i. In the central nervous system (CNS), the olfactory bulbs displayed the highest uptake; up to six times the activity in blood. Pre-administration of unlabeled CLINDE, PK11195 and Ro 5-4864 (1 mg/kg) reduced the uptake of [(123)I]-CLINDE by 70-55% in olfactory bulbs. In the kidney and heart, a reduction of 60-80% ID/g was observed, while an increase was observed in the adrenals requiring 10 mg/kg for significant displacement. Flumazenil had no effect on uptake in peripheral organs and brain. Metabolite analysis indicated >90% of the radioactivity in the above tissues was intact [(123)I]-CLINDE. [(123)I]-CLINDE displays high and selective uptake for the PBBS and warrants further development as a probe for imaging PBBS using single photon emission computed tomography (SPECT).

Trinucleotide Insertions, Deletions, and Point Mutations in Glucose Transporters Confer K+ Uptake in Saccharomyces cerevisiae

PubMed Central

Liang, Hong; Ko, Christopher H.; Herman, Todd; Gaber, Richard F.

1998-01-01

Deletion of TRK1 and TRK2 abolishes high-affinity K+ uptake in Saccharomyces cerevisiae, resulting in the inability to grow on typical synthetic growth medium unless it is supplemented with very high concentrations of potassium. Selection for spontaneous suppressors that restored growth of trk1Δ trk2Δ cells on K+-limiting medium led to the isolation of cells with unusual gain-of-function mutations in the glucose transporter genes HXT1 and HXT3 and the glucose/galactose transporter gene GAL2. 86Rb uptake assays demonstrated that the suppressor mutations conferred increased uptake of the ion. In addition to K+, the mutant hexose transporters also conferred permeation of other cations, including Na+. Because the selection strategy required such gain of function, mutations that disrupted transporter maturation or localization to the plasma membrane were avoided. Thus, the importance of specific sites in glucose transport could be independently assessed by testing for the ability of the mutant transporter to restore glucose-dependent growth to cells containing null alleles of all of the known functional glucose transporter genes. Twelve sites, most of which are conserved among eukaryotic hexose transporters, were revealed to be essential for glucose transport. Four of these have previously been shown to be essential for glucose transport by animal or plant transporters. Eight represented sites not previously known to be crucial for glucose uptake. Each suppressor mutant harbored a single mutation that altered an amino acid(s) within or immediately adjacent to a putative transmembrane domain of the transporter. Seven of 38 independent suppressor mutations consisted of in-frame insertions or deletions. The nature of the insertions and deletions revealed a striking DNA template dependency: each insertion generated a trinucleotide repeat, and each deletion involved the removal of a repeated nucleotide sequence. PMID:9447989

Retention in care and reasons for discontinuation of lifelong antiretroviral therapy in a cohort of Cameroonian pregnant and breastfeeding HIV-positive women initiating 'Option B+' in the South West Region.

PubMed

Atanga, Pascal N; Ndetan, Harrison T; Achidi, Eric A; Meriki, Henry D; Hoelscher, Michael; Kroidl, Arne

2017-02-01

To assess linkage and retention in care along the PMTCT cascade in HIV-positive pregnant and breastfeeding women initiating Option B+ in Cameroon. We prospectively determined uptake of HIV testing and counselling (HTC), uptake of ART and retention in care after Option B+ initiation between October 2013 and December 2014 in pregnant and breastfeeding women from five sites within the Kumba Health District. Retention in care was assessed over at least 12 months follow-up and estimated by Kaplan-Meier analysis. During follow-up, tracing outcomes and reasons for discontinuing treatment were documented. The uptake of HTC of 5813 women with unknown HIV status was 98.5%, 251 (4.4%) were newly diagnosed HIV positive, and ART uptake in women eligible to start Option B+ was 96.8%. We enrolled 268 women initiating lifelong ART in the follow-up. Overall, 65 (24.3%) discontinued treatment, either defined by loss to follow-up (44.6%) or actively stopped treatment (55.8%). Retention in care was 88.0% and 81.1% at 6 and 12 months, respectively. Discontinuation was significantly associated in multivariate analysis with small sites and high staff turnover [aOR 2.5 (95% CI 1.6, 3.9), P < 0.001]. Main reasons for stopping treatment were HIV status denial and stigma (52.8%), religious reasons (25.0%) and lack of transport fare (11.1%). We observed good uptake of HTC, ART and retention in care, which declined over time. Discontinuation of Option B+ was highest at small sites with a high staff turnover. Improved staffing, adequate task shifting and community interventions to track defaulters including reducing stigma and religious beliefs may improve Option B+ retention. © 2016 John Wiley & Sons Ltd.

Plutonium Particle Migration in the Shallow Vadose Zone: The Nevada Test Site as an Analog Site

NASA Astrophysics Data System (ADS)

Hunt, J. R.; Smith, D. K.

2004-12-01

The upper meter of the vadose zone in desert environments is the horizon where wastes have been released and human exposure is determined through dermal, inhalation, and food uptake pathways. This region is also characterized by numerous coupled processes that determine contaminant transport, including precipitation infiltration, evapotranspiration, daily and annual temperature cycling, dust resuspension, animal burrowing, and geochemical weathering reactions. While there is considerable interest in colloidal transport of minerals, pathogenic organisms, and contaminants in the vadose zone, there are limited field sites where the actual occurrence of contaminant migration can be quantified over the appropriate spatial and temporal scales of interest. At the US Department of Energy Nevada Test Site, there have been numerous releases of radionuclides since the 1950's that have become field-scale tracer tests. One series of tests was the four safety shots conducted in an alluvial valley of Area 11 in the 1950's. These experiments tested the ability of nuclear materials to survive chemical explosions without initiating fission reactions. Four above-ground tests were conducted and they released plutonium and uranium on the desert valley floor with only one of the tests undergoing some fission. Shortly after the tests, the sites were surveyed for radionuclide distribution on the land surface using aerial surveys and with depth. Additional studies were conducted in the 1970's to better understand the fate of plutonium in the desert that included studies of depth distribution and dust resuspension. More recently, plutonium particle distribution in the soil profile was detected using autoradiography. The results to date demonstrate the vertical migration of plutonium particles to depths in excess of 30 cm in this arid vadose zone. While plutonium migration at the Nevada Test Site has been and continues to be a concern, these field experiments have become analog sites for the release of radiological materials potentially important to consequence management investigations. In particular, these 50-year old experiments with long and detailed site investigations under relative undisturbed conditions offer insights into transport pathways that must be represented in simulation models that evaluate responses to radiological dispersal devices (RDDs). A compilation of the available site characterization data suggests additional experimental and modeling programs that can ultimately quantify the fate of contaminant particles released at the soil surface.

Electrochemistry suggests proton access from the exit site to the binuclear center in Paracoccus denitrificans cytochrome c oxidase pathway variants.

PubMed

Meyer, Thomas; Melin, Frédéric; Richter, Oliver-M H; Ludwig, Bernd; Kannt, Aimo; Müller, Hanne; Michel, Hartmut; Hellwig, Petra

2015-02-27

Two different pathways through which protons access cytochrome c oxidase operate during oxygen reduction from the mitochondrial matrix, or the bacterial cytoplasm. Here, we use electrocatalytic current measurements to follow oxygen reduction coupled to proton uptake in cytochrome c oxidase isolated from Paracoccus denitrificans. Wild type enzyme and site-specific variants with defects in both proton uptake pathways (K354M, D124N and K354M/D124N) were immobilized on gold nanoparticles, and oxygen reduction was probed electrochemically in the presence of varying concentrations of Zn(2+) ions, which are known to inhibit both the entry and the exit proton pathways in the enzyme. Our data suggest that under these conditions substrate protons gain access to the oxygen reduction site via the exit pathway. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Community and Ecosystem-Level Impacts of an Emergent Macrophyte on the Ventura River, California.

NASA Astrophysics Data System (ADS)

Simpson, J.; Leydecker, A.; Melack, J.

2005-05-01

Ludwigia hexapetala is a pervasive, emergent vascular plant on the lower Ventura River. Presence of this plant appears to facilitate growth of shade-tolerant diatoms, while indirectly inhibiting filamentous green macroalgae. Four sites on the river were monitored during 2003; three downstream of a wastewater treatment plant, where Ludwigia is present, and one upstream site where it is absent. Filamentous algae occurred at all four sites, but declined rapidly at the below-treatment plant sites as growth and cover of vascular plants increased. By late summer, percent cover at these sites was dominated by Ludwigia, while the upstream site was consistently dominated by green macroalgae. Submerged plant parts provided substrate for diatom colonization, roughly doubling benthic diatom biomass (measured as chlorophyll a) at the downstream sites. Presence of the Ludwigia population also had strong ecosystem-level effects. The wastewater effluent produced typical stream water nitrate concentrations of 100-200 uM. Nitrate uptake rates downstream of the treatment plant inputs averaged 5 kg N/km/day, and direct uptake by Ludwigia could account for 20-40% of this nitrate drawdown. Further nitrate removal from the water column may be indirectly facilitated by the presence of Ludwigia through facilitation of diatom population growth.

Oxygen interaction with disordered and nanostructured Ag(001) surfaces

NASA Astrophysics Data System (ADS)

Vattuone, L.; Burghaus, U.; Savio, L.; Rocca, M.; Costantini, G.; Buatier de Mongeot, F.; Boragno, C.; Rusponi, S.; Valbusa, U.

2001-08-01

We investigated O2 adsorption on Ag(001) in the presence of defects induced by Ne+ sputtering at different crystal temperatures, corresponding to different surface morphologies recently identified by scanning tunneling microscopy. The gas-phase molecules were dosed with a supersonic molecular beam. The total sticking coefficient and the total uptake were measured with the retarded reflector method, while the adsorption products were characterized by high resolution electron energy loss spectroscopy. We find that, for the sputtered surfaces, both sticking probability and total O2 uptake decrease. Molecular adsorption takes place also for heavily damaged surfaces but, contrary to the flat surface case, dissociation occurs already at a crystal temperature, T, of 105 K. The internal vibrational frequency of the O2 admolecules indicates that two out of the three O2- moieties present on the flat Ag(001) surface are destabilized by the presence of defects. The dissociation probability depends on surface morphology and drops for sputtering temperatures larger than 350 K, i.e., when surface mobility prevails healing the defects. The latter, previously identified with kink sites, are saturated at large O2 doses. The vibrational frequency of the oxygen adatoms, produced by low temperature dissociation, indicates the formation of at least two different adatom moieties, which we tentatively assign to oxygen atoms at kinks and vacancies.

Characterization of the effects of serotonin on the release of (/sup 3/H)dopamine from rat nucleus accumbens and striatal slices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nurse, B.; Russell, V.A.; Taljaard, J.J.

1988-05-01

The effect of serotonin agonists on the depolarization (K+)-induced, calcium-dependent, release of (/sup 3/H)dopamine (DA) from rat nucleus accumbens and striatal slices was investigated. Serotonin enhanced basal /sup 3/H overflow and reduced K+-induced release of (/sup 3/H)DA from nucleus accumbens slices. The effect of serotonin on basal /sup 3/H overflow was not altered by the serotonin antagonist, methysergide, or the serotonin re-uptake blocker, chlorimipramine, but was reversed by the DA re-uptake carrier inhibitors nomifensine and benztropine. With the effect on basal overflow blocked, serotonin did not modulate K+-induced release of (/sup 3/H)DA in the nucleus accumbens or striatum. The serotoninmore » agonists, quipazine (in the presence of nomifensine) and 5-methoxytryptamine, did not significantly affect K+-induced release of (/sup 3/H)DA in the nucleus accumbens. This study does not support suggestions that serotonin receptors inhibit the depolarization-induced release of dopamine in the nucleus accumbens or striatum of the rat brain. The present results do not preclude the possibility that serotonin may affect the mesolimbic reward system at a site which is post-synaptic to dopaminergic terminals in the nucleus accumbens.« less

Localization of azithromycin in Toxoplasma gondii-infected cells.

PubMed Central

Schwab, J C; Cao, Y; Slowik, M R; Joiner, K A

1994-01-01

Agents effective against intracellular pathogens must enter infected cells, crossing vacuolar membranes surrounding the organisms and then penetrating into the microbe and localizing to the microbial target site. We have characterized these parameters for azithromycin entry into Toxoplasma gondii-infected Chinese hamster ovary cells and murine macrophage-like J774 cells. Azithromycin uptake into infected host cells was concentrative and was dependent upon proton gradients. Subcellular fractionation of azithromycin-loaded infected CHO cells demonstrated > 95% intracellular drug in host cell lysosomes and cytosol, with < 5% associated with the parasite. Uptake of azithromycin into the T. gondii vacuole increased if parasites were coated with antibody prior to internalization by murine J774 cells, conditions which result in the formation of acidified phagolysosomes. No redistribution or retention of azithromycin in the parasite was observed when drug efflux from antibiotic-loaded infected CHO cells was monitored. Azithromycin entry into extracellular T. gondii was concentrative, was temperature and pH dependent, and was not different when azithromycin-sensitive and -resistant parasites were compared. These results demonstrate that azithromycin concentrates primarily in acidified compartments in parasites and host cells. The high concentration of azithromycin within these compartments may not be biologically relevant to inhibition of intracellular parasite growth by this agent. PMID:7979295

β-cyclodextrin functionalized poly (5-amidoisophthalicacid) grafted Fe3O4 magnetic nanoparticles: A novel biocompatible nanocomposite for targeted docetaxel delivery

NASA Astrophysics Data System (ADS)

Tarasi, Roghayeh; Khoobi, Mehdi; Niknejad, Hassan; Ramazani, Ali; Ma'mani, Leila; Bahadorikhalili, Saeed; Shafiee, Abbas

2016-11-01

Thiol-lactam initiated radical polymerization (TLIRP) was successfully employed to prepare poly-N-5-acrylamidoisophthalicacid grafted onto Fe3O4 magnetic nanoparticles (MNPs@PAIP). β-Cyclodextrin (CD) was then conjugated to the carboxylic groups of the prepared MNPs via carbodiimide activation. Subsequently, tumor-targeting folic acid (FA) was attached to the hydroxyl groups of CD on the surface of the latter MNPs to increase the site-specific intracellular delivery. The prepared MNPs were fully characterized by FTIR, VSM, TGA, XRD, FE-SEM and TEM. Docetaxel (DTX) as hydrophobic anticancer drug was loaded via host-guest inclusion complexation with CD and the release profile of the system was studied at different pH. The effect of MNPs on the cell viability was evaluated for the human embryonic kidney normal cell line (HEK293) as well as HeLa and MDA-MB-231 cancerous cell lines and the results did not show any apparent cytotoxic effect. In comparison, DTX loaded MNPs reduced the growth of HeLa and MDA-MB-231 cells more than free DTX. Intracellular uptake ability of DTX loaded MNPs was also studied using fluorescent microscopy and showed cellular uptake about 90% after 4 h treatment.

Transferrin-tailored solid lipid nanoparticles as vectors for site-specific delivery of temozolomide to brain

NASA Astrophysics Data System (ADS)

Jain, Aviral; Singhai, Priyanka; Gurnany, Ekta; Updhayay, Satish; Mody, Nishi

2013-03-01

Blood-brain barrier restricts the uptake of many important hydrophilic drugs and limits their efficacy in the treatment of brain diseases because of the presence of tight junctions, high metabolic capacity, low pinocytic vesicular traffic, and efficient efflux mechanisms. In the present project, transferrin (Tf)-conjugated solid lipid nanoparticles (Tf-SLNs) were investigated for their ability to deliver temozolomide (TMZ) to the brain. SLNs were prepared by an ethanol injection method using hydrogenated soya phosphatidylcholine, triolein, cholesterol and distearoylphosphatidylethanolamine. Conjugation of SLNs with Tf was achieved by incubation of Tf with TMZ-loaded SLNs in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride in phosphate buffered saline (pH 7.4) as a cross linker. SLNs preparation were characterized for particle size, polydispersity index, zeta potential, surface morphology, percent drug entrapment efficiency, in vitro drug release, and hemolytic toxicity studies. In vitro cytotoxicity studies were performed on human cancer cell lines. The average size was found to be 221 ± 3.22 nm with entrapment efficiency of 69.83 ± 2.52 and 249 ± 2.61 nm with entrapment efficiency decreased to 64.21 ± 2.27 % for unconjugated SLNs and Tf-SLNs, respectively. Fluorescence studies revealed the enhanced uptake of Tf-SLNs in brain tissue compared with unconjugated SLNs.

Lower Respiratory Tract Infection of the Ferret by 2009 H1N1 Pandemic Influenza A Virus Triggers Biphasic, Systemic, and Local Recruitment of Neutrophils.

PubMed

Camp, Jeremy V; Bagci, Ulas; Chu, Yong-Kyu; Squier, Brendan; Fraig, Mostafa; Uriarte, Silvia M; Guo, Haixun; Mollura, Daniel J; Jonsson, Colleen B

2015-09-01

Infection of the lower respiratory tract by influenza A viruses results in increases in inflammation and immune cell infiltration in the lung. The dynamic relationships among the lung microenvironments, the lung, and systemic host responses during infection remain poorly understood. Here we used extensive systematic histological analysis coupled with live imaging to gain access to these relationships in ferrets infected with the 2009 H1N1 pandemic influenza A virus (H1N1pdm virus). Neutrophil levels rose in the lungs of H1N1pdm virus-infected ferrets 6 h postinfection and became concentrated at areas of the H1N1pdm virus-infected bronchiolar epithelium by 1 day postinfection (dpi). In addition, neutrophil levels were increased throughout the alveolar spaces during the first 3 dpi and returned to baseline by 6 dpi. Histochemical staining revealed that neutrophil infiltration in the lungs occurred in two waves, at 1 and 3 dpi, and gene expression within microenvironments suggested two types of neutrophils. Specifically, CCL3 levels, but not CXCL8/interleukin 8 (IL-8) levels, were higher within discrete lung microenvironments and coincided with increased infiltration of neutrophils into the lung. We used live imaging of ferrets to monitor host responses within the lung over time with [(18)F]fluorodeoxyglucose (FDG). Sites in the H1N1pdm virus-infected ferret lung with high FDG uptake had high levels of proliferative epithelium. In summary, neutrophils invaded the H1N1pdm virus-infected ferret lung globally and focally at sites of infection. Increased neutrophil levels in microenvironments did not correlate with increased FDG uptake; hence, FDG uptake may reflect prior infection and inflammation of lungs that have experienced damage, as evidenced by bronchial regeneration of tissues in the lungs at sites with high FDG levels. Severe influenza disease is characterized by an acute infection of the lower airways that may progress rapidly to organ failure and death. Well-developed animal models that mimic human disease are essential to understanding the complex relationships of the microenvironment, organ, and system in controlling virus replication, inflammation, and disease progression. Employing the ferret model of H1N1pdm virus infection, we used live imaging and comprehensive histological analyses to address specific hypotheses regarding spatial and temporal relationships that occur during the progression of infection and inflammation. We show the general invasion of neutrophils at the organ level (lung) but also a distinct pattern of localized accumulation within the microenvironment at the site of infection. Moreover, we show that these responses were biphasic within the lung. Finally, live imaging revealed an early and sustained host metabolic response at sites of infection that may reflect damage and repair of tissues in the lungs. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Lower Respiratory Tract Infection of the Ferret by 2009 H1N1 Pandemic Influenza A Virus Triggers Biphasic, Systemic, and Local Recruitment of Neutrophils

PubMed Central

Camp, Jeremy V.; Bagci, Ulas; Chu, Yong-Kyu; Squier, Brendan; Fraig, Mostafa; Uriarte, Silvia M.; Guo, Haixun; Mollura, Daniel J.

2015-01-01

ABSTRACT Infection of the lower respiratory tract by influenza A viruses results in increases in inflammation and immune cell infiltration in the lung. The dynamic relationships among the lung microenvironments, the lung, and systemic host responses during infection remain poorly understood. Here we used extensive systematic histological analysis coupled with live imaging to gain access to these relationships in ferrets infected with the 2009 H1N1 pandemic influenza A virus (H1N1pdm virus). Neutrophil levels rose in the lungs of H1N1pdm virus-infected ferrets 6 h postinfection and became concentrated at areas of the H1N1pdm virus-infected bronchiolar epithelium by 1 day postinfection (dpi). In addition, neutrophil levels were increased throughout the alveolar spaces during the first 3 dpi and returned to baseline by 6 dpi. Histochemical staining revealed that neutrophil infiltration in the lungs occurred in two waves, at 1 and 3 dpi, and gene expression within microenvironments suggested two types of neutrophils. Specifically, CCL3 levels, but not CXCL8/interleukin 8 (IL-8) levels, were higher within discrete lung microenvironments and coincided with increased infiltration of neutrophils into the lung. We used live imaging of ferrets to monitor host responses within the lung over time with [18F]fluorodeoxyglucose (FDG). Sites in the H1N1pdm virus-infected ferret lung with high FDG uptake had high levels of proliferative epithelium. In summary, neutrophils invaded the H1N1pdm virus-infected ferret lung globally and focally at sites of infection. Increased neutrophil levels in microenvironments did not correlate with increased FDG uptake; hence, FDG uptake may reflect prior infection and inflammation of lungs that have experienced damage, as evidenced by bronchial regeneration of tissues in the lungs at sites with high FDG levels. IMPORTANCE Severe influenza disease is characterized by an acute infection of the lower airways that may progress rapidly to organ failure and death. Well-developed animal models that mimic human disease are essential to understanding the complex relationships of the microenvironment, organ, and system in controlling virus replication, inflammation, and disease progression. Employing the ferret model of H1N1pdm virus infection, we used live imaging and comprehensive histological analyses to address specific hypotheses regarding spatial and temporal relationships that occur during the progression of infection and inflammation. We show the general invasion of neutrophils at the organ level (lung) but also a distinct pattern of localized accumulation within the microenvironment at the site of infection. Moreover, we show that these responses were biphasic within the lung. Finally, live imaging revealed an early and sustained host metabolic response at sites of infection that may reflect damage and repair of tissues in the lungs. PMID:26063430

Plant selective uptake of halogenated flame retardants at an e-waste recycling site in southern China.

PubMed

Wang, Shaorui; Wang, Yan; Luo, Chunling; Li, Jun; Yin, Hua; Zhang, Gan

2016-07-01

The concentrations and homolog patterns of halogenated flame retardants (HFRs) in vegetables grown at an e-waste contaminated site were investigated. Polybrominated diphenyl ethers (PBDEs) were the dominant HFRs in vegetable tissues, with concentrations ranging from 10.3 to 164 ng g(-1) and 1.16-107 ng g(-1) in shoots and roots, respectively, followed by novel brominated flame retardants (NBFRs) and dechlorane plus (DPs). This is an indication that PBDE contamination in vegetables grown around e-waste recycling sites may pose a risk to the local terrestrial ecosystem and residents. In addition, this is the first report on the concentrations and compositions of NBFRs in vegetables around e-waste recycling sites. The HFRs concentrations in vegetables varied greatly with the vegetable species, with the highest concentrations observed in Brassica oleracea var. capitata. Root concentration factors (RCF) decreased with increasing log Kow of HFRs, which indicated that the uptake of HFRs was controlled mainly by log Kow. Dissimilar HFRs profiles in shoots and roots suggested that the uptake and translocation of HFRs by plants were selective, with lower halogenated congeners prone to accumulation in vegetable tissues. Positive relationships between PBDEs and their substitutes were observed in vegetable tissues, suggesting that the replacement of PBDEs by NBFRs has not resulted in an obvious transition in plants within the study area. Copyright © 2016 Elsevier Ltd. All rights reserved.

Variation in salt marsh CO2 fluxes across a latitudinal gradient along the US Atlantic coast

NASA Astrophysics Data System (ADS)

Forbrich, I.; Nahrawi, H. B.; Leclerc, M.; O'Connell, J. L.; Mishra, D. R.; Fogarty, M. C.; Edson, J. B.; Lule, A. V.; Vargas, R.; Giblin, A. E.; Alber, M.

2017-12-01

Salt marshes occur at the dynamic interface of land and ocean, where they play an important role as sink and source of nutrients, carbon (C) and sediment. They often are strong carbon sinks, because they continuously accumulate soil organic matter and sediment to keep their position relative to sea level. Decadal average C sequestration rates can be inferred from soil carbon density and mass accumulation rates, but little information about biological and climatic controls on C cycling and storage in these systems exists. In this study, we report measurements of atmospheric CO2 exchange from salt marshes along the US Atlantic coast from Massachusetts to Georgia. These measurements were made over periods from one to five years. Spartina alterniflora is the dominant vegetation at all sites. At the northern most site, Plum Island Ecosystems (PIE) LTER, and the southern most site, Georgia Coastal Ecosystems (GCE) LTER, flux measurements over several years have shown variations in the net CO2 flux influenced by the local climate. For example, annual net C uptake at the PIE LTER over 5 years (2013-2017) depends on rainfall in the growing season (June-August) which modulates soil salinity levels. This pattern is not as evident at the GCE LTER (2014-2015). Furthermore, the growing season length differs between both sites. Based on the CO2 flux measurements, a temperature threshold of 15o C limits the net C uptake at both sites and daily rates of net C uptake are generally smaller during the longer growing season in Georgia. Nevertheless, gross primary production (GPP) is similar for both sites. We will extend this analysis to include sites from Delaware and North Carolina to assess controls (e.g. leaf area using MODIS vegetation indices, temperature, photoperiod) on Spartina phenology and CO2 exchange.

BOREAS TE-1 CH4 Flux Data Over The SSA-OA

NASA Technical Reports Server (NTRS)

Anderson, Darwin; Papagno, Andrea; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor)

2000-01-01

The BOREAS TE-1 team collected various data to characterize the soil-plant systems in the BOREAS SSA. Particular emphasis was placed on nutrient biochemistry, the stores and transfers of organic carbon, and how the characteristics were related to measured methane fluxes. The overall transect in the Prince Albert National Park (Saskatchewan, Canada) included the major plant communities and related soils that occurred in that section of the boreal forest. Soil physical, chemical, and biological measurements along the transect were used to characterize the static environment, which allowed them to be related to methane fluxes. Chamber techniques were used to provide a measure of methane production/uptake. Chamber measurements coupled with flask sampling were used to determine the seasonality of methane fluxes. This particular data set contains methane flux and soil profile methane concentration values from the SSA-OA site. The data were collected from 29-May to 17-Sep-1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Clay Minerals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mueller, Karl T.; Sanders, Rebecca L.; Washton, Nancy M.

2014-03-14

Clay minerals are important components of the environment and are involved or implicated in processes such as the uptake of pollutants and the release of nutrients and as potential platforms for a number of chemical reactions. Owing to their small particle sizes (typically, on the order of microns or smaller) and mixing with a variety of other minerals and soil components, advanced characterization methods are needed to study their structures, dynamics, and reactivities. In this article, we describe the use of solid-state NMR methods to characterize the structures and chemistries of clay minerals. Early one-pulse magic-angle spinning (MAS) NMR studiesmore » of 27Al and 29Si have now been enhanced and extended with new studies utilizing advanced methodologies (such as Multiple Quantum MAS) as well as studies of less-sensitive nuclei. In additional work, the issue of reactivity of clay minerals has been addressed, including studies of reactive surface area in the environment. Utilizations of NMR-sensitive nuclides within the clay minerals themselves, and in molecules that react with specific sites on the clay mineral surfaces, have aided in understanding the reactivity of these complex aluminosilicate systems.« less

BOREAS TE-1 SSA-Fen Soil Profile Nutrient Data

NASA Technical Reports Server (NTRS)

Papagno, Andrea; Anderson, Darwin; Newcomer, Jeffrey A. (Editor); Hall, Forrest G. (Editor)

2000-01-01

The BOREAS TE-1 team collected various data to characterize the soil-plant systems in the BOREAS SSA. Particular emphasis was placed on nutrient biochemistry, the stores and transfers of organic carbon, and how the characteristics were related to measured methane fluxes. The overall traniect in the Prince Albert National Park (Saskatchewan, Canada) included the major plant communities and related soils that occurred in that section of the boreal forest. Soil physical, chemical, and biological measurements along the transect were used to characterize the static environment, which allowed them to be related to methane fluxes. Chamber techniques were used to provide a measure of methane production/uptake. Chamber measurements coupled with flask sampling were used to determine the seasonality of methane fluxes. This particular data set contains soil profile measurements of various nutrients at the SSA-Fen site. The data were collected from 23-May to 21-Oct- 1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Estimated carrier frequency of creatine transporter deficiency in females in the general population using functional characterization of novel missense variants in the SLC6A8 gene.

PubMed

DesRoches, Caro-Lyne; Patel, Jaina; Wang, Peixiang; Minassian, Berge; Salomons, Gajja S; Marshall, Christian R; Mercimek-Mahmutoglu, Saadet

2015-07-10

Creatine transporter deficiency (CRTR-D) is an X-linked inherited disorder of creatine transport. All males and about 50% of females have intellectual disability or cognitive dysfunction. Creatine deficiency on brain proton magnetic resonance spectroscopy and elevated urinary creatine to creatinine ratio are important biomarkers. Mutations in the SLC6A8 gene occur de novo in 30% of males. Despite reports of high prevalence of CRTR-D in males with intellectual disability, there are no true prevalence studies in the general population. To determine carrier frequency of CRTR-D in the general population we studied the variants in the SLC6A8 gene reported in the Exome Variant Server database and performed functional characterization of missense variants. We also analyzed synonymous and intronic variants for their predicted pathogenicity using in silico analysis tools. Nine missense variants were functionally analyzed using transient transfection by site-directed mutagenesis with In-Fusion HD Cloning in HeLa cells. Creatine uptake was measured by liquid chromatography tandem mass spectrometry for creatine measurement. The c.1654G>T (p.Val552Leu) variant showed low residual creatine uptake activity of 35% of wild type transfected HeLa cells and was classified as pathogenic. Three variants (c.808G>A; p.Val270Met, c.942C>G; p.Phe314Leu and c.952G>A; p.Ala318Thr) were predicted to be pathogenic based on in silico analysis, but proved to be non-pathogenic by our functional analysis. The estimated carrier frequency of CRTR-D was 0.024% in females in the general population. We recommend functional studies for all novel missense variants by transient transfection followed by creatine uptake measurement by liquid chromatography tandem mass spectrometry as fast and cost effective method for the functional analysis of missense variants in the SLC6A8 gene. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

The levels of boron-uptake proteins in roots are correlated with tolerance to boron stress in barley

USDA-ARS?s Scientific Manuscript database

Boron (B) is an essential micronutrient required for plant growth and development. Recently, two major B-uptake proteins, BOR1 and NIP5;1 have been identified and partially characterized. BOR1 is a high-affinity B transporter involved in xylem loading in roots, and NIP5;1 acts is a major boric-acid ...

Recognizing critical mine spoil health characteristics to design biochars for site improvement to promote stabilizing plant growth

EPA Science Inventory

Biochar can be used as an amendment to remediate metal-contaminated mine spoils for improved site phytostabilization. For successful phytostabilization to occur, biochar amendments must improve mine spoil health with respect to plant rooting plus uptake of water and nutrients. ...

Mechanisms of cell uptake, inflammatory potential and protein corona effects with gold nanoparticles.

PubMed

Li, Yang; Monteiro-Riviere, Nancy A

2016-12-01

To assess inflammation, cellular uptake and endocytic mechanisms of gold nanoparticles (AuNP) in human epidermal keratinocytes with and without a protein corona. Human epidermal keratinocytes were exposed to 40 and 80 nm AuNP with lipoic acid, polyethylene glycol (PEG) and branched polyethyleneimine (BPEI) coatings with and without a protein corona up to 48 h. Inhibitors were selected to characterize endocytosis. BPEI-AuNP showed the greatest uptake, while PEG-AuNP had the least. Protein coronas decreased uptake and affected their mechanism. AuNP uptake was energy-dependent, except for 40 nm lipoic-AuNP. Most AuNP were internalized by clathrin and lipid raft-mediated endocytosis, except for 40 nm PEG was by raft/noncaveolae mediated endocytosis. Coronas inhibited caveolae-mediated-endocytosis with lipoic acid and BPEI-AuNP and altered 40 nm PEG-AuNP from raft/noncaveolae to clathrin. Inflammatory responses decreased with a plasma corona. Results suggest protein coronas significantly affect cellular uptake and inflammatory responses of AuNP.

Metal uptake by homegrown vegetables – The relative importance in human health risk assessments at contaminated sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Augustsson, Anna L.M., E-mail: anna.augustsson@lnu.se; Uddh-Söderberg, Terese E.; Hogmalm, K. Johan

Risk assessments of contaminated land often involve the use of generic bioconcentration factors (BCFs), which express contaminant concentrations in edible plant parts as a function of the concentration in soil, in order to assess the risks associated with consumption of homegrown vegetables. This study aimed to quantify variability in BCFs and evaluate the implications of this variability for human exposure assessments, focusing on cadmium (Cd) and lead (Pb) in lettuce and potatoes sampled around 22 contaminated glassworks sites. In addition, risks associated with measured Cd and Pb concentrations in soil and vegetable samples were characterized and a probabilistic exposure assessmentmore » was conducted to estimate the likelihood of local residents exceeding tolerable daily intakes. The results show that concentrations in vegetables were only moderately elevated despite high concentrations in soil, and most samples complied with applicable foodstuff legislation. Still, the daily intake of Cd (but not Pb) was assessed to exceed toxicological thresholds for about a fifth of the study population. Bioconcentration factors were found to vary more than indicated by previous studies, but decreasing BCFs with increasing metal concentrations in the soil can explain why the calculated exposure is only moderately affected by the choice of BCF value when generic soil guideline values are exceeded and the risk may be unacceptable. - Highlights: • Uptake of Cd and Pb by lettuce and potatoes increased with soil contamination. • Consumption of homegrown vegetables may lead to a daily Cd intake above TDIs. • The variability in the calculated BCFs is high when compared to previous studies. • Exposure assessments are most sensitive to the choice of BCFs at low contamination.« less

How do land management practices affect net ecosystem CO2 exchange of an invasive plant infestation?

NASA Astrophysics Data System (ADS)

Sonnentag, O.; Detto, M.; Runkle, B.; Kelly, M.; Baldocchi, D. D.

2009-12-01

Ecosystem gas and energy exchanges of invasive plant infestations under different land management practices have been subject of few studies and thus little is known. Our goal is to characterize seasonal changes in net ecosystem CO2 exchange (NEE) through the processes of photosynthesis (GEP) and ecosystem respiration (Reco) of a grassland used as pasture yet infested by perennial pepperweed (Lepidium latifolium) in California’s Sacramento-San Joaquin River Delta. We analyze eddy-covariance supported by environmental and canopy-scale hyperspectral reflectance measurements acquired in 2007-2009. Our study covers three summer drought periods with slightly different land management practices. Over the study period the site was subject to year-round grazing, and in 2008 the site was additionally mowed. Specific questions we address are a) how does pepperweed flowering affect GEP, b) does a mowing event affect NEE mainly through GEP or Reco, and c) can the combined effects of phenology and mowing on pepperweed NEE potentially be tracked using routinely applied remote sensing techniques? Preliminary results indicate that pepperweed flowering drastically decreases photosynthetic CO2 uptake due to shading by the dense arrangement of white flowers at the canopy top, causing the infestation to be almost CO2 neutral. In contrast, mowing causes the infestation to act as moderate net CO2 sink, mainly due to increased CO2 uptake during regrowth. We demonstrate that spectral regions other than commonly-used red and near-infrared might be more promising for pepperweed monitoring because of its spectral uniqueness during the flowering phase. Our results have important implications for land-use land-cover (LULC) change studies when biological invasions and their management alter ecosystem structure and functioning but not necessarily the respective LULC class.

Beneficial reuse and sustainability: the fate of organic compounds in land-applied waste.

PubMed

Overcash, Michael; Sims, Ronald C; Sims, Judith L; Nieman, J Karl C

2005-01-01

Land application systems, also referred to as beneficial reuse systems, are engineered systems that have defined and permitted application areas based on site and waste characteristics to determine the land area size requirement. These terrestrial systems have orders of magnitude greater microbial capability and residence time to achieve decomposition and assimilation compared with aquatic systems. In this paper we focus on current information and information needs related to terrestrial fate pathways in land treatment systems. Attention is given to conventional organic chemicals as well as new estrogenic and pharmaceutical chemicals of commerce. Specific terrestrial fate pathways addressed include: decomposition, bound residue formation, leaching, runoff, and crop uptake. Molecular decomposition and formation of bound residues provide the basis for the design and regulation of land treatment systems. These mechanisms allow for assimilation of wastes and nondegradation of the environment and accomplish the goal of sustainable land use. Bound residues that are biologically produced are relatively immobile, degrade at rates similar to natural soil materials, and should present a significantly reduced risk to the environment as opposed to parent contaminants. With regard to leaching and runoff pathways, no comprehensive summary or mathematical model of organic chemical migration from land treatment systems has been developed. For the crop uptake pathway, a critical need exists to develop information for nonagricultural chemicals and to address full-scale performance and monitoring at more land application sites. The limited technology choices for treatment of biosolids, liquids, and other wastes implies that acceptance of some risks and occurrence of some benefits will continue to characterize land application practices that contribute directly to the goal of beneficial reuse and sustainability.

Selective synthesis and characterization of chlorins as sensitizers for photodynamic therapy

NASA Astrophysics Data System (ADS)

Montforts, Franz-Peter; Kusch, Dirk; Hoper, Frank; Braun, Stefan; Gerlach, Benjamin; Brauer, Hans-Dieter; Schermann, Guido; Moser, Joerg G.

1996-04-01

Chlorin type sensitizers have ideal photophysical properties for an application in PDT. The basic chlorin framework of these sensitizers has to be modified by attachment of lipophilic and hydrophilic residues to achieve a good cell uptake and tumor enrichment. In the present study we describe the selective synthesis of amphiphilic chlorins starting from the readily accessible red blood pigment heme. The photophysical properties of the well defined synthetic chlorins are characterized by photophysical investigations. The kinetic of cell uptake, the localization in the cell and the photodynamic behavior of the amphiphilic sensitizers are demonstrated by incubation of A 375 cancer cell lines with structurally different chlorins.

Coupling of NAD+ Biosynthesis and Nicotinamide Ribosyl Transport: Characterization of NadR Ribonucleotide Kinase Mutants of Haemophilus influenzae

PubMed Central

Merdanovic, Melisa; Sauer, Elizabeta; Reidl, Joachim

2005-01-01

Previously, we characterized a pathway necessary for the processing of NAD+ and for uptake of nicotinamide riboside (NR) in Haemophilus influenzae. Here we report on the role of NadR, which is essential for NAD+ utilization in this organism. Different NadR variants with a deleted ribonucleotide kinase domain or with a single amino acid change were characterized in vitro and in vivo with respect to cell viability, ribonucleotide kinase activity, and NR transport. The ribonucleotide kinase mutants were viable only in a nadV+ (nicotinamide phosphoribosyltransferase) background, indicating that the ribonucleotide kinase domain is essential for cell viability in H. influenzae. Mutations located in the Walker A and B motifs and the LID region resulted in deficiencies in both NR phosphorylation and NR uptake. The ribonucleotide kinase function of NadR was found to be feedback controlled by NAD+ under in vitro conditions and by NAD+ utilization in vivo. Taken together, our data demonstrate that the NR phosphorylation step is essential for both NR uptake across the inner membrane and NAD+ synthesis and is also involved in controlling the NAD+ biosynthesis rate. PMID:15968050

Coupling of NAD+ biosynthesis and nicotinamide ribosyl transport: characterization of NadR ribonucleotide kinase mutants of Haemophilus influenzae.

PubMed

Merdanovic, Melisa; Sauer, Elizabeta; Reidl, Joachim

2005-07-01

Previously, we characterized a pathway necessary for the processing of NAD+ and for uptake of nicotinamide riboside (NR) in Haemophilus influenzae. Here we report on the role of NadR, which is essential for NAD+ utilization in this organism. Different NadR variants with a deleted ribonucleotide kinase domain or with a single amino acid change were characterized in vitro and in vivo with respect to cell viability, ribonucleotide kinase activity, and NR transport. The ribonucleotide kinase mutants were viable only in a nadV+ (nicotinamide phosphoribosyltransferase) background, indicating that the ribonucleotide kinase domain is essential for cell viability in H. influenzae. Mutations located in the Walker A and B motifs and the LID region resulted in deficiencies in both NR phosphorylation and NR uptake. The ribonucleotide kinase function of NadR was found to be feedback controlled by NAD+ under in vitro conditions and by NAD+ utilization in vivo. Taken together, our data demonstrate that the NR phosphorylation step is essential for both NR uptake across the inner membrane and NAD+ synthesis and is also involved in controlling the NAD+ biosynthesis rate.

Macrophages phagocytose nonopsonized silica particles using a unique microtubule-dependent pathway

PubMed Central

Gilberti, Renée M.; Knecht, David A.

2015-01-01

Silica inhalation leads to the development of the chronic lung disease silicosis. Macrophages are killed by uptake of nonopsonized silica particles, and this is believed to play a critical role in the etiology of silicosis. However, the mechanism of nonopsonized-particle uptake is not well understood. We compared the molecular events associated with nonopsonized- and opsonized-particle phagocytosis. Both Rac and RhoA GTPases are activated upon nonopsonized-particle exposure, whereas opsonized particles activate either Rac or RhoA. All types of particles quickly generate a PI(3,4,5)P3 and F-actin response at the particle attachment site. After formation of a phagosome, the events related to endolysosome-to-phagosome fusion do not significantly differ between the pathways. Inhibitors of tyrosine kinases, actin polymerization, and the phosphatidylinositol cascade prevent opsonized- and nonopsonized-particle uptake similarly. Inhibition of silica particle uptake prevents silica-induced cell death. Microtubule depolymerization abolished uptake of complement-opsonized and nonopsonized particles but not Ab-opsonized particles. Of interest, regrowth of microtubules allowed uptake of new nonopsonized particles but not ones bound to cells in the absence of microtubules. Although complement-mediated uptake requires macrophages to be PMA-primed, untreated cells phagocytose nonopsonized silica and latex. Thus it appears that nonopsonized-particle uptake is accomplished by a pathway with unique characteristics. PMID:25428990

Factors Influencing Uptake of Sylvatic Plague Vaccine Baits by Prairie Dogs.

PubMed

Abbott, Rachel C; Russell, Robin E; Richgels, Katherine L D; Tripp, Daniel W; Matchett, Marc R; Biggins, Dean E; Rocke, Tonie E

2017-11-20

Sylvatic plague vaccine (SPV) is a virally vectored bait-delivered vaccine expressing Yersinia pestis antigens that can protect prairie dogs (Cynomys spp.) from plague and has potential utility as a management tool. In a large-scale 3-year field trial, SPV-laden baits containing the biomarker rhodamine B (used to determine bait consumption) were distributed annually at a rate of approximately 100-125 baits/hectare along transects at 58 plots encompassing the geographic ranges of four species of prairie dogs. We assessed site- and individual-level factors related to bait uptake in prairie dogs to determine which were associated with bait uptake rates. Overall bait uptake for 7820 prairie dogs sampled was 70% (95% C.I. 69.9-72.0). Factors influencing bait uptake rates by prairie dogs varied by species, however, in general, heavier animals had greater bait uptake rates. Vegetation quality and day of baiting influenced this relationship for black-tailed, Gunnison's, and Utah prairie dogs. For these species, baiting later in the season, when normalized difference vegetation indices (a measure of green vegetation density) are lower, improves bait uptake by smaller animals. Consideration of these factors can aid in the development of species-specific SPV baiting strategies that maximize bait uptake and subsequent immunization of prairie dogs against plague.

Factors influencing uptake of sylvatic plague vaccine baits by prairie dogs

USGS Publications Warehouse

Abbott, Rachel C.; Russell, Robin E.; Richgels, Katherine; Tripp, Daniel W.; Matchett, Marc R.; Biggins, Dean E.; Rocke, Tonie E.

2017-01-01

Sylvatic plague vaccine (SPV) is a virally vectored bait-delivered vaccine expressing Yersinia pestis antigens that can protect prairie dogs (Cynomys spp.) from plague and has potential utility as a management tool. In a large-scale 3-year field trial, SPV-laden baits containing the biomarker rhodamine B (used to determine bait consumption) were distributed annually at a rate of approximately 100–125 baits/hectare along transects at 58 plots encompassing the geographic ranges of four species of prairie dogs. We assessed site- and individual-level factors related to bait uptake in prairie dogs to determine which were associated with bait uptake rates. Overall bait uptake for 7820 prairie dogs sampled was 70% (95% C.I. 69.9–72.0). Factors influencing bait uptake rates by prairie dogs varied by species, however, in general, heavier animals had greater bait uptake rates. Vegetation quality and day of baiting influenced this relationship for black-tailed, Gunnison’s, and Utah prairie dogs. For these species, baiting later in the season, when normalized difference vegetation indices (a measure of green vegetation density) are lower, improves bait uptake by smaller animals. Consideration of these factors can aid in the development of species-specific SPV baiting strategies that maximize bait uptake and subsequent immunization of prairie dogs against plague.

Microscale characterization of dissolved organic matter production and uptake in marine microbial mat communities

NASA Technical Reports Server (NTRS)

Paerl, H. W.; Bebout, B. M.; Joye, S. B.; Des Marais, D. J.

1993-01-01

Intertidal marine microbial mats exhibited biologically mediated uptake of low molecular weight dissolved organic matter (DOM), including D-glucose, acetate, and an L-amino acid mixture at trace concentrations. Uptake of all compounds occurred in darkness, but was frequently enhanced under natural illumination. The photosystem 2 inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) generally failed to inhibit light-stimulated DOM uptake. Occasionally, light plus DCMU-amended treatments led to uptake rates higher than light-incubated samples, possibly due to phototrophic bacteria present in subsurface anoxic layers. Uptake was similar with either 3H- or 14C-labeled substrates, indicating that recycling of labeled CO2 via photosynthetic fixation was not interfering with measurements of light-stimulated DOM uptake. Microautoradiographs showed a variety of pigmented and nonpigmented bacteria and, to a lesser extent, cyanobacteria and eucaryotic microalgae involved in light-mediated DOM uptake. Light-stimulated DOM uptake was often observed in bacteria associated with sheaths and mucilage surrounding filamentous cyanobacteria, revealing a close association of organisms taking up DOM with photoautotrophic members of the mat community. The capacity for dark- and light-mediated heterotrophy, coupled to efficient retention of fixed carbon in the mat community, may help optimize net production and accretion of mats, even in oligotrophic waters.

Importance of plant species and external silicon concentration to active silicon uptake and transport.

PubMed

Liang, Yongchao; Hua, Haixia; Zhu, Yong-Guan; Zhang, Jie; Cheng, Chunmei; Römheld, Volker

2006-01-01

Here, we characterized silicon (Si) uptake and xylem loading in Oryza sativa, Zea mays, Helianthus annuus and Benincase hispida in a series of hydroponic experiments. Both active and passive Si-uptake components co-exist in all the plants tested. The active component is the major mechanism responsible for Si uptake in O. sativa and Z. mays. By contrast, passive uptake prevails in H. annuus and B. hispida at a higher external Si concentration (0.85 mM), while the active component constantly exists and contributes to the total Si uptake, especially at a lower external Si concentration (0.085 mM). Short experiments showed that Si uptake was significantly suppressed in O. sativa and Z. mays by metabolic inhibitors or low temperature, regardless of external Si concentrations. By contrast, Si uptake in H. annuus and B. hispida was inhibited more significantly by metabolic inhibitors or low temperature at lower (for example, 0.085 mM) than at higher (for example, 1.70 mM) external Si concentrations. It can be concluded that both active and passive Si-uptake components co-exist in O. sativa, Z. mays, H. annuus and B. hispida, with their relative contribution being dependent much upon both plant species and external Si concentrations.

Immobilization and Natural Attenuation of Arsenic in Surface and Subsurface Sediments

NASA Astrophysics Data System (ADS)

O'Day, P. A.; Illera, V.; Choi, S.; Vlassopoulos, D.

2008-12-01

Understanding of molecular-scale biogeochemical processes that control the mobilization and distribution of As and other oxyanions can be used to develop remediation strategies that take advantage of natural geochemical and hydrologic gradients. Arsenic and other toxic oxyanions can be mobilized at low bulk sediment concentrations (ppm range) and thus, treatment technologies are challenged by low contaminant concentrations, widespread sources, variable pH and Eh conditions, and inaccessibility of subsurface environments. In situ chemical amendments to soils and sediments can be used to decrease the mobility and bioaccessibility of As and oxyanions through sorption to, or precipitation with, stabilizing phases. At a site near San Francisco Bay (CA, USA), treatment of As-contaminated soils with sulfate-cement amendments has effectively immobilized As. Laboratory experiments with field soils and spectroscopic characterizations showed that in high pH cement-type treatments, As is precipitated in ettringite-type phases (Ca-Al sulfates), whereas in low pH ferrous sulfate treatments, As is associated with an iron-arsenate phase (angellelite). The presence of As-associated ettringite-type phases in field sediments amended more than a decade ago indicates long-term stability of these neophases, as long as environmental conditions are relatively constant. At sites of subsurface contamination, monitored natural attenuation (MNA) as a remediation approach for As is gaining interest and acceptance. Successful implementation of MNA requires a mechanistic understanding of As sequestration processes and of the subsurface conditions that may enhance or reduce long-term effectiveness. At a former military site (MA, USA), naturally occurring As was mobilized from sediments as a result of reducing conditions from addition of organic carbon as a biodegradation treatment of chlorinated solvents. Elevated As concentrations were not detected further than about 30 m downgradient of the injection, indicating that As sequestration was also occurring by natural processes in the aquifer. Laboratory experiments with aquifer sediments and spectroscopic characterization of reaction products were used to quantify the extent of As(III) sorption and abiotic oxidation to As(V), probably by Mn(III,IV) present in sediment minerals. Interrogation by XANES spectroscopy and analysis of uptake data indicated that sediments have a limited abiotic oxidation capacity for As(III), which did not exceed 30% of the total amount of As sorbed and was estimated at 0.025 to 0.4 mmol/kg sediment. Results indicate that pH-controlled sorption is the primary mechanism for As uptake and sediment capacity for oxidative sorption is limited. As such, MNA may be temporarily effective at this site, depending on the size of the contaminant plume and the rate of groundwater flow.

Through form to function: root hair development and nutrient uptake

NASA Technical Reports Server (NTRS)

Gilroy, S.; Jones, D. L.

2000-01-01

Root hairs project from the surface of the root to aid nutrient and water uptake and to anchor the plant in the soil. Their formation involves the precise control of cell fate and localized cell growth. We are now beginning to unravel the complexities of the molecular interactions that underlie this developmental regulation. In addition, after years of speculation, nutrient transport by root hairs has been demonstrated clearly at the physiological and molecular level, with evidence for root hairs being intense sites of H(+)-ATPase activity and involved in the uptake of Ca(2+), K(+), NH(4)(+), NO(3)(-), Mn(2+), Zn(2+), Cl(-) and H(2)PO(4)(-).

RedOx-controlled sorption of iodine anions by hydrotalcite composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levitskaia, Tatiana G.; Chatterjee, Sayandev; Arey, Bruce W.

2016-01-01

The radioactive contaminant iodine-129 (I-129) is one of the top risk drivers at radiological waste disposal and contaminated groundwater sites where nuclear material fabrication or reprocessing has occurred. Currently there are very few options available to treat I-129 in the groundwater, which is partially related to its complex biogeochemical behavior in the subsurface and occurrence in the multiple chemical forms. We hypothesize that layered hydrotalcite materials containing redox active transition metal ions offer a potential solution, benefiting from the simultaneous adsorption of iodate (IO3-) and iodide (I-) anions, which exhibit different electronic and structural properties and therefore may require dissimilarmore » hosts. To test this hypothesis, Cr3+- based materials were selected based on the rationale that Cr3+ readily reduces IO3- in solution. It was combined with either redox-active Co2+ or redox-inactive Ni2+ so that two model materials were prepared by hydrothermal synthesis including Co2+-Cr3+ and Ni2+-Cr3+(M-Cr). Obtained M-Cr materials comprised of Co2+-Cr3+ or Ni2+-Cr3+ layered hydrotalcite and small fractions of Co3O4 spinel or Ni(OH)2 theophrastite phases were structurally characterized before and after uptake of periodate (IO4-), IO3-, and I- anions. It was found that the IO3- uptake is driven by its chemical reduction to I2 and I-. Interestingly, in the Co2+-Cr3+ hydrotalcite, Co2+ and not Cr3+ serves as a reductant while in the Ni2+-Cr3+ hydrotalcite Cr3+ is responsible for the reduction of IO3-. A different uptake mechanism was identified for the IO4- anion. The Co2+-Cr3+ hydrotalcite phase efficiently uptakes IO4- by a diffusion-limited ion exchange mechanism and is not accompanied by the redox process, while Cr3+ in the Ni2+-Cr3+ hydrotalcite reduces IO4- to IO3-, I2 and I-. Iodide exhibited high affinity only to the Co-Cr material. The Co-Cr material performed remarkably well for the removal of IO3-, I- and total iodine from the groundwater collected from the US DOE Hanford site, WA, USA outperforming non-redox active hydrotalcites (e.g., Mg2+-Al3+) reported previously. This work demonstrates that redox-controlled sorption can be a highly effective method for the treatment of anions based on elements with mobile oxidation states. Further, multiple anions of interest could be simultaneously removed through combination of approaches.« less

Developing a Suitable Model for Water Uptake for Biodegradable Polymers Using Small Training Sets.

PubMed

Valenzuela, Loreto M; Knight, Doyle D; Kohn, Joachim

2016-01-01

Prediction of the dynamic properties of water uptake across polymer libraries can accelerate polymer selection for a specific application. We first built semiempirical models using Artificial Neural Networks and all water uptake data, as individual input. These models give very good correlations (R (2) > 0.78 for test set) but very low accuracy on cross-validation sets (less than 19% of experimental points within experimental error). Instead, using consolidated parameters like equilibrium water uptake a good model is obtained (R (2) = 0.78 for test set), with accurate predictions for 50% of tested polymers. The semiempirical model was applied to the 56-polymer library of L-tyrosine-derived polyarylates, identifying groups of polymers that are likely to satisfy design criteria for water uptake. This research demonstrates that a surrogate modeling effort can reduce the number of polymers that must be synthesized and characterized to identify an appropriate polymer that meets certain performance criteria.

Calcium-ion transport by intact Ehrlich ascites-tumour cells. Role of respiratory substrates, Pi and temperature.

PubMed

Charlton, R R; Wenner, C E

1978-03-15

1. The interaction of intact Ehrlich ascites-tumour cells with Ca2+ at 37 degrees C consists of Ca2+ uptake followed by efflux from the cells. Under optimum conditions, two or three cycles of uptake and efflux are observed in the first 15 min after Ca2+ addition. 2. The respiratory substrates malate, succinate and ascorbate plus p-phenylenediamine support Ca2+ uptake. Ca2+ uptake at 37 degrees C is sensitive to the respiratory inhibitors rotenone and antimycin A when appropriate substrates are present. Ca2+ uptake and retention are inhibited by the uncoupler S-13. 3. Increasing extracellular Pi (12 to 30 mM) stimulates uncoupler-sensitive Ca2+ uptake, which reaches a maximum extent of 15 nmol/mg of protein when supported by succinate respiration. Ca2+ efflux is partially inhibited at 30 mM-Pi. 4. Optimum Ca2+ uptake occurs in the presence of succinate and Pi, suggesting that availability of substrate and Pi are rate-limiting. K. Ca2+ uptake occurs at 4 degrees C and is sensitive to uncouplers and oligomycin. Ca2+ efflux at this temperature is minimal. These data are consistent with a model in which passive diffusion of Ca2+ through the plasma membrane is followed by active uptake by the mitochondria. Ca2+ uptake is supported by substrates entering respiration at all three energy-coupling sites. Ca2+ efflux appears to be an active process with a high temperature coefficient.

Uptake of heavy metals by Typha capensis from wetland sites polluted by effluent from mineral processing plants: implications of metal-metal interactions.

PubMed

Zaranyika, M F; Nyati, W

2017-10-01

The aim of the present work was to demonstrate the existence of metal-metal interactions in plants and their implications for the absorption of toxic elements like Cr. Typha capensis , a good accumulator of heavy metals, was chosen for the study. Levels of Fe, Cr, Ni, Cd, Pb, Cu and Zn were determined in the soil and roots, rhizomes, stems and leaves of T. capensis from three Sites A, B and C polluted by effluent from a chrome ore processing plant, a gold ore processing plant, and a nickel ore processing plant, respectively. The levels of Cr were extremely high at Site A at 5415 and 786-16,047 μg g -1 dry weight in the soil and the plant, respectively, while the levels of Ni were high at Site C at 176 and 24-891 μg g -1 in the soil and the plant, respectively. The levels of Fe were high at all three sites at 2502-7500 and 906-13,833 μg g -1 in the soil and plant, respectively. For the rest of the metals, levels were modest at 8.5-148 and 2-264 μg g -1 in the soil and plant, respectively. Pearson's correlation analysis confirmed mutual synergistic metal-metal interactions in the uptake of Zn, Cu, Co, Ni, Fe, and Cr, which are attributed to the similarity in the radii and coordination geometry of the cations of these elements. The implications of such metal-metal interactions (or effects of one metal on the behaviour of another) on the uptake of Cr, a toxic element, and possible Cr detoxification mechanism within the plant, are discussed.

The sites of catabolism of murine monomeric IgA.

PubMed

Moldoveanu, Z; Epps, J M; Thorpe, S R; Mestecky, J

1988-07-01

The tissue sites of monomeric IgA (mIgA) catabolism were determined in a BALB/c mouse model. Mouse mIgA myeloma proteins were labeled either by direct iodination or by coupling the residualizing label, dilactitol-125I-tyramine (125I-DLT) to the proteins; catabolites from protein labeled with 125I-DLT accumulate at the site of protein degradation, allowing identification of the tissue and cellular sites involved in catabolism of the protein. The circulating half-lives of 125I- and 125I-DLT-mIgA were the same. The distribution of radioactivity in tissues was measured at 1, 3, 24, and 96 h after iv. injection of 125I-DLT-labeled mIgA, dimeric IgA (dIgA), IgG, or mouse serum albumin. The greatest uptake of 125I-DLT-mIgA was attributable to the liver. This organ accounted for more internal catabolism of mIgA than all other tissues combined. In contrast, 125I-DLT-IgG was catabolized equally in skin, muscle, and liver. These data indicate that, in mice, the liver is the major site of mIgA catabolism. To determine the cell types involved, collagenase digestion was used to isolate parenchymal and non-parenchymal cells from perfused liver of animals injected with 125-DLT-mIgA. Most of the radioactivity was associated with the hepatocyte fraction, even though both cell types showed uptake of 125I-DLT-mIgA. Inhibition studies, with asialofetuin and mouse IgA demonstrated that the uptake of mIgA by liver cells was mediated primarily by the asialoglycoprotein receptor.

2016 winter campaigns on ClNO2 and N2O5 at a mountain top and a semi-rural site in southern China: overview and initial results

NASA Astrophysics Data System (ADS)

Wang, T.; Wang, W.; Yun, H.; Tham, Y. J.; Xia, M.; Yu, C.; Wang, Z.; Zhang, N.; Cui, L.; Poon, S.; Lee, S.; Ou, Y.; Yue, D.; Zhai, Y.

2017-12-01

In the past decade, heterogeneous uptake of dinitrogen pentoxide (N2O5) on aerosol and subsequent production of nitryl chloride (ClNO2) have been found to impact the oxidative capacity, NOx fate, and the formation of aerosol nitrate and photochemical ozone. However, the detailed processes and effects are not completely understand for diverse environments of the globe. Our previous measurements at a mountain top (957 m a.s.l) in Hong Kong in winter 2013 revealed elevated concentrations of N2O5 (up to 7.7 ppb) and ClNO2 (up to 4.7 ppb) and that the polluted air masses originated from inland urban areas of the Pearl River delta (PRD). To understand the detailed uptake processes, an intensive measurement campaign was conducted at the same site (Tai Mo Shan, TMS) during October-December 2016 and at a semi-rural site (Heshan) in the center of the PRD in January 2017. Key parameters related to N2O5 and ClNO2 processes, including aerosol ionic composition, aerosol number and size, volatile organic compounds as well as ozone, NOx and NOy, were measured during the two campaigns. Elevated (up to 3.4 ppb) ClNO2 concentrations were observed at the mountain site on many nights a few hours after sunset, and extremely high levels of ClNO2 (up to 8.3 ppb) were measured in the inland site during a heavy pollution event. The meteorological conditions and variations of ClNO2 will be examined with concurrently measured parameters to elucidate factors determining N2O5 uptake and ClNO2 production. The 2016 results at TMS will be compared with those from 2013.

The [NiFe]-hydrogenase of the cyanobacterium Synechocystis sp. PCC 6803 works bidirectionally with a bias to H2 production.

PubMed

McIntosh, Chelsea L; Germer, Frauke; Schulz, Rüdiger; Appel, Jens; Jones, Anne K

2011-07-27

Protein film electrochemistry (PFE) was utilized to characterize the catalytic activity and oxidative inactivation of a bidirectional [NiFe]-hydrogenase (HoxEFUYH) from the cyanobacterium Synechocystis sp. PCC 6803. PFE provides precise control of the redox potential of the adsorbed enzyme so that its activity can be monitored under changing experimental conditions as current. The properties of HoxEFUYH are different from those of both the standard uptake and the "oxygen-tolerant" [NiFe]-hydrogenases. First, HoxEFUYH is biased toward proton reduction as opposed to hydrogen oxidation. Second, despite being expressed under aerobic conditions in vivo, HoxEFUYH is clearly not oxygen-tolerant. Aerobic inactivation of catalytic hydrogen oxidation by HoxEFUYH is total and nearly instantaneous, producing two inactive states. However, unlike the Ni-A and Ni-B inactive states of standard [NiFe]-hydrogenases, both of these states are quickly (<90 s) reactivated by removal of oxygen and exposure to reducing conditions. Third, proton reduction continues at 25-50% of the maximal rate in the presence of 1% oxygen. Whereas most previously characterized [NiFe]-hydrogenases seem to be preferential hydrogen oxidizing catalysts, the cyanobacterial enzyme works effectively in both directions. This unusual catalytic bias as well as the ability to be quickly reactivated may be essential to fulfilling the physiological role in cyanobacteria, organisms expected to experience swings in cellular reduction potential as they switch between aerobic conditions in the light and dark anaerobic conditions. Our results suggest that the uptake [NiFe]-hydrogenases alone are not representative of the catalytic diversity of [NiFe]-hydrogenases, and the bidirectional heteromultimeric enzymes may serve as valuable models to understand the diverse mechanisms of tuning the reactivity of the hydrogen activating site.

The tau positron-emission tomography tracer AV-1451 binds with similar affinities to tau fibrils and monoamine oxidases.

PubMed

Vermeiren, Céline; Motte, Philippe; Viot, Delphine; Mairet-Coello, Georges; Courade, Jean-Philippe; Citron, Martin; Mercier, Joël; Hannestad, Jonas; Gillard, Michel

2018-02-01

Lilly/Avid's AV-1451 is one of the most advanced tau PET tracers in the clinic. Although results obtained in Alzheimer's disease patients are compelling, discrimination of tracer uptake in healthy individuals and patients with supranuclear palsy (PSP) is less clear as there is substantial overlap of signal in multiple brain regions. Moreover, accurate quantification of [ 18 F]AV-1451 uptake in Alzheimer's disease may not be possible. The aim of the present study was to characterize the in vitro binding of AV-1451 to understand and identify potential off-target binding that could explain the poor discrimination observed in PSP patients. [ 3 H]AV-1451 and AV-1451 were characterized in in vitro binding assays using recombinant and native proteins/tissues from postmortem samples of controls and Alzheimer's disease and PSP patients. [ 3 H]AV-1451 binds to multiple sites with nanomolar affinities in brain homogenates and to tau fibrils isolated from Alzheimer's disease or PSP patients. [ 3 H]AV-1451 also binds with similarly high affinities in brain homogenates devoid of tau pathology. This unexpected binding was demonstrated to be because of nanomolar affinities of [ 3 H]AV-1451 for monoamine oxidase A and B enzymes. High affinity of AV-1451 for monoamine oxidase proteins may limit its utility as a tau PET tracer in PSP and Alzheimer's disease because of high levels of monoamine oxidase expression in brain regions also affected by tau deposition, especially if monoamine oxidase levels change over time or with a treatment intervention. © 2017 International Parkinson and Movement Disorder Society. © 2017 International Parkinson and Movement Disorder Society.

A False-Negative Case of Primary Central Nervous System Lymphoma on 11C-Methionine PET and Intense 18F-FDG Uptake.

PubMed

García-Garzon, J R; Villasboas-Rosciolesi, Diego; Baquero, Miguel; Bassa, Pere; Soler, Marina; Riera, Eduard

2016-08-01

We report a case of a 44-year-old man with neurological symptoms and MRI findings, which were unable to differentiate between glioma and lymphoma. Metabolic characterization by means of PET imaging with F-FDG and C-methionine is proposed to determine the benign or tumor (high- and low-grade) origin of brain lesions. In this case, the MRI lesion corresponded with an inconclusive metabolic pattern of intense F-FDG uptake and no significant C-methionine uptake. Pathological study revealed a false-negative case of C-methionine due to lymphoma.

Nitrogen dynamics in Turbic Cryosols from Siberia and Greenland☆

PubMed Central

Wild, Birgit; Schnecker, Jörg; Bárta, Jiří; Čapek, Petr; Guggenberger, Georg; Hofhansl, Florian; Kaiser, Christina; Lashchinsky, Nikolaj; Mikutta, Robert; Mooshammer, Maria; Šantrůčková, Hana; Shibistova, Olga; Urich, Tim; Zimov, Sergey A.; Richter, Andreas

2013-01-01

Turbic Cryosols (permafrost soils characterized by cryoturbation, i.e., by mixing of soil layers due to freezing and thawing) are widespread across the Arctic, and contain large amounts of poorly decomposed organic material buried in the subsoil. This cryoturbated organic matter exhibits retarded decomposition compared to organic material in the topsoil. Since soil organic matter (SOM) decomposition is known to be tightly linked to N availability, we investigated N transformation rates in different soil horizons of three tundra sites in north-eastern Siberia and Greenland. We measured gross rates of protein depolymerization, N mineralization (ammonification) and nitrification, as well as microbial uptake of amino acids and NH4+ using an array of 15N pool dilution approaches. We found that all sites and horizons were characterized by low N availability, as indicated by low N mineralization compared to protein depolymerization rates (with gross N mineralization accounting on average for 14% of gross protein depolymerization). The proportion of organic N mineralized was significantly higher at the Greenland than at the Siberian sites, suggesting differences in N limitation. The proportion of organic N mineralized, however, did not differ significantly between soil horizons, pointing to a similar N demand of the microbial community of each horizon. In contrast, absolute N transformation rates were significantly lower in cryoturbated than in organic horizons, with cryoturbated horizons reaching not more than 32% of the transformation rates in organic horizons. Our results thus indicate a deceleration of the entire N cycle in cryoturbated soil horizons, especially strongly reduced rates of protein depolymerization (16% of organic horizons) which is considered the rate-limiting step in soil N cycling. PMID:24302785

Enlightening mineral iron sensing in Pseudomonas fluorescens by surface active maghemite nanoparticles: Involvement of the OprF porin.

PubMed

Magro, Massimiliano; Fasolato, Luca; Bonaiuto, Emanuela; Andreani, Nadia Andrea; Baratella, Davide; Corraducci, Vittorino; Miotto, Giovanni; Cardazzo, Barbara; Vianello, Fabio

2016-10-01

Mineral iron(III) recognition by bacteria is considered a matter of debate. The peculiar surface chemistry of novel naked magnetic nanoparticles, called SAMNs (surface active maghemite nanoparticles) characterized by solvent exposed Fe(3+) sites on their surface, was exploited for studying mineral iron sensing in Pseudomonas fluorescens. SAMNs were applied for mimicking Fe(3+) ions in solution, acting as magnetically drivable probes to evaluate putative Fe(3+) recognition sites on the microorganism surface. Culture broths and nano-bio-conjugates were characterized by UV-Vis spectroscopy and mass spectrometry. The whole heritage of a membrane porin (OprF) of P. fluorescens Ps_22 cells was recognized and firmly bound by SAMNs. The binding of nanoparticles to OprF porin was correlated to a drastic inhibition of a siderophore (pyoverdine) biosynthesis and to the stimulation of the production and rate of formation of a secondary siderophore. The analysis of metabolic pathways, based on P. fluorescens Ps_22 genomic information, evidenced that this putative secondary siderophore does not belong to a selection of the most common siderophores. In the scenario of an adhesion mechanism, it is plausible to consider OprF as the biological component deputed to the mineral iron sensing in P. fluorescens Ps_22, as well as one key of siderophore regulation. The present work sheds light on mineral iron sensing in microorganisms. Peculiar colloidal naked iron oxide nanoparticles offer a useful approach for probing the adhesion of bacterial surface on mineral iron for the identification of the specific recognition site for this iron uptake regulation in microorganisms. Copyright © 2016 Elsevier B.V. All rights reserved.

[11C]choline uptake in regenerating liver after partial hepatectomy or CCl4-administration.

PubMed

Sasaki, Toru

2004-02-01

To characterize [methyl-(11)C]choline ([(11)C]choline) as an oncologic PET radiopharmaceutical, [(11)C]choline uptake in regenerating livers after partial hepatectomy as a model of typical proliferating tissue and after CCl(4) insult as that of proliferating tissue with inflammation, was studied in rats. [(11)C]Choline, [(18)F]2-fluoro-2-deoxy-D-glucose ([(18)F]FDG) and [2-(14)C]thymidine ([(14)C]TdR) uptake was studied in regenerating rat liver after 70% partial hepatectomy or CCl(4)-administration. [(11)C]Choline uptake in regenerating liver after partial hepatectomy was significantly increased with [(14)C]TdR uptake as a marker of DNA synthesis at 18 hours after surgery. On the other hand, the uptake was not accelerated by CCl(4)-administration, though it significantly increased [(14)C]TdR uptake. There were no differences of [(11)C]choline uptake acceleration following partial hepatectomy among the three parts of the regenerating liver. [(18)F]FDG uptake was accelerated in the regenerating liver on either partial hepatectomy or CCl(4)-administration. The magnitude of the increase in [(18)F]FDG uptake in the regenerating liver induced by partial hepatectomy was greater than that for [(11)C]choline. [(11)C]Choline uptake in the liver was accelerated by partial hepatectomy, but not by CCl(4)-administration. This might be expected given that the differentiation between proliferating tissues such as tumor and inflammatory tissue was possible by [(11)C]choline-PET.

A novel approach to investigate the uptake and internalization of Escherichia coli O157:H7 in spinach cultivated in soil and hydroponic media

USDA-ARS?s Scientific Manuscript database

Internalization of E. coli O157:H7 into spinach plants through root uptake is a potential route of contamination. A Tn7-based plasmid vector was used to insert the green fluorescent protein (gfp) gene into the attTn7 site in the E. coli chromosome. Three gfp-labeled E. coli inocula, O157:H7 strains ...

Gallium-67 imaging in muscular sarcoidosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edan, G.; Bourguet, P.; Delaval, P.

1984-07-01

A case is presented of sarcoid myopathy in which radiogallium was seen to accumulate in the sites of muscle involvement. Uptake of the radiotracer disappeared following institution of corticosteroid therapy. The exceptional nature of this case contrasts with the high frequency of biopsy evidence of sarcoid granulomas in muscle. Gallium-67 imaging can be used to determine the extent of muscle involvement and, through evaluation of uptake intensity, the degree of disease activity before and after treatment.

Inorganic N and P dynamics of Antarctic glacial meltwater streams as controlled by hyporheic exchange and benthic autotrophic communities

USGS Publications Warehouse

McKnight, Diane M.; Runkel, R.L.; Tate, C.M.; Duff, J.H.; Moorhead, D.L.

2004-01-01

The McMurdo Dry Valleys of South Victoria Land, Antarctica, contain numerous glacial meltwater streams that drain into lakes on the valley floors. Many of the streams have abundant perennial mats of filamentous cyanobacteria. The algal mats grow during streamflow in the austral summer and are in a dormant freeze-dried state during the rest of the year. NO3 and soluble reactive P (SRP) concentrations were lower in streams with abundant algal mats than in streams with sparse algal mats. NO3 and SRP concentrations were higher in the hyporheic zone of a stream with abundant algal mats than in the stream itself. An experimental injection of LiCl, NaNO3, and K3PO4 was conducted in Green Creek, which has abundant algal mats. Substantial hyporheic exchange occurred. The NO3 and PO4 concentrations at 50 m below the injection were 55 ??M and 18 ??M, respectively, during the experiment. NO3 and PO4 concentrations were below the detection limit of 1 to 2 ??M at a site 497 m below the injection during the Cl tracer arrival, indicating a high capacity for nutrient uptake by algal communities. NO2 and NH4 were present at sites 226 and 327 m below the injection, indicating that, in addition to denitrification and algal uptake, dissimilatory NO3 reduction to NO2 and NH4 may be a NO3 sink during transport. Transport modelling with nutrient uptake represented as a 1st-order process yielded reach-scale parameters of 4.3 ?? 10-5 to 3.9 ?? 10-4/s and 1.4 ?? 10-4 to 3.8 ?? 10 -4/s for uptake of NO3 and PO4, respectively. The best match with the observed data was a model in which PO4 uptake occurred only in the main channel and NO3 uptake occurred in the main channel and in the hyporheic zone. Hyporheic NO3 uptake was 7 to 16% of the total uptake for the different stream reaches. These results demonstrate that nutrient flux to the lakes is controlled by hyporheic exchange and nutrient uptake by algal mats in dry valley streams. Streams without algal mats contribute more nutrients to the lakes than streams with algal mats.

A novel Online-to-Offline (O2O) model for pre-exposure prophylaxis and HIV testing scale up

PubMed Central

Anand, Tarandeep; Nitpolprasert, Chattiya; Trachunthong, Deondara; Kerr, Stephen J; Janyam, Surang; Linjongrat, Danai; Hightow-Weidman, Lisa B; Phanuphak, Praphan; Ananworanich, Jintanat; Phanuphak, Nittaya

2017-01-01

Abstract Introduction: PrEP awareness and uptake among men who have sex with men (MSM) and transgender women (TG) in Thailand remains low. Finding ways to increase HIV testing and PrEP uptake among high-risk groups is a critical priority. This study evaluates the effect of a novel Adam’s Love Online-to-Offline (O2O) model on PrEP and HIV testing uptake among Thai MSM and TG and identifies factors associated with PrEP uptake. Methods: The O2O model was piloted by Adam’s Love (www.adamslove.org) HIV educational and counselling website. MSM and TG reached online by PrEP promotions and interested in free PrEP and/or HIV testing services contacted Adam’s Love online staff, received real-time PrEP eCounseling, and completed online bookings for receiving services at one of the four sites in Bangkok based on their preference. Auto-generated site- and service-specific e-tickets and Quick Response (QR) codes were sent to their mobile devices enabling monitoring and check-in by offline site staff. Service uptake and participant’s socio-demographic and risk behaviour characteristics were analyzed. Factors associated with PrEP uptake were assessed using multiple logistic regression. Results: Between January 10th and April 11th, 2016, Adam’s Love reached 272,568 people online via the PrEP O2O promotions. 425 MSM and TG received eCounseling and e-tickets. There were 325 (76.5%) MSM and TG who checked-in at clinics and received HIV testing. Nine (2.8%) were diagnosed with HIV infection. Median (IQR) time between receiving the e-ticket and checking-in was 3 (0–7) days. Of 316 HIV-negative MSM and TG, 168 (53.2%) started PrEP. In a multivariate model, higher education (OR 2.30, 95%CI 1.14–4.66; p = 0.02), seeking sex partners online (OR 2.05, 95%CI 1.19–3.54; p = 0.009), being aware of sexual partners’ HIV status (OR 2.37, 95%CI 1.29–4.35; p = 0.008), ever previously using post-exposure prophylaxis (PEP) (OR 2.46, 95%CI 1.19–5.09; p = 0.01), and enrolment at Adam’s Love clinic compared to the other three sites (OR 3.79, 95%CI 2.06–6.95; p < 0.001) were independently associated with PrEP uptake. Conclusions: Adam’s Love O2O model is highly effective in linking online at-risk MSM and TG to PrEP and HIV testing services, and has high potential to be replicated and scaled up in other settings with high Internet penetration among key populations. PMID:28362062

Cadmium and calcium uptake in the mollusc donax rugosus and effect of a calcium channel blocker

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sidoumou, Z.; Gnassia-Barelli, M.; Romeo, M.

Donax rugosus, a common bivalve mollusc in the coastal waters of Mauritania, has been studied for trace metal concentrations as a function of sampling site (from South of Mauritania to the North of this country) and of season. In this paper, the uptake of cadmium was experimentally studied in the different organs of D. rugosus. Since metals such as cadmium, copper and mercury may alter calcium homeostasis, calcium uptake was also studied in the animals treated with cadmium. Since calcium is taken up through specific channels, it appears that metals inhibit Ca uptake by interacting with these channels in themore » plasma membrane. Cadmium and calcium have very similar atomic radii, thus cadmium may be taken up through the calcium channels, particularly through voltage-dependent channels. The uptake of cadmium and calcium by D. Rugosus was therefore also studied in the presence of the calcium channel blocker verapamil. 13 refs., 3 figs., 1 tab.« less

N-isopropyl-(/sup 123/I)p-iodoamphetamine: single-pass brain uptake and washout; binding to brain synaptosomes; and localization in dog and monkey brain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winchell, H.S.; Horst, W.D.; Braun, L.

1980-10-01

The kinetics of N-isopropyl-p-(/sup 123/I)iodoamphetamine in rat brains were determined by serial measurements of brain uptake index (BUI) after intracarotid injection; also studied were its effects on amine uptake and release in rat's brain cortical synaptosomes; and its in vivo distribution in the dog and monkey. No specific localization in brain nuclei of the dog was seen, but there was progressive accumulation in the eyes. Rapid initial brain uptake in the ketamine-sedated monkey was noted, and further slow brain uptake occurred during the next 20 min but without retinal localization. High levels of brain activity were maintained for several hours.more » The quantitative initial single-pass clearance of the agent in the brain suggests its use in evaluation of regional brain perfusion. Its interaction with brain amine-binding sites suggests its possible application in studies of cerebral amine metabolism.« less

All puffed out: do pufferfish hold their breath while inflated?

PubMed Central

McGee, Georgia Evelyn; Clark, Timothy Darren

2014-01-01

The inflation response of pufferfishes is one of the most iconic predator defence strategies in nature. Current dogma suggests that pufferfish inflation represents a breath-holding response, whereby gill oxygen uptake ceases for the duration of inflation and cutaneous respiration increases to compensate. Here, we show that the black-saddled pufferfish (Canthigaster valentini) has an excellent capacity for oxygen uptake while inflated, with uptake rates increasing to five-times that of resting levels. Moreover, we show that this species has negligible capacity for cutaneous respiration, concluding that the gills are the primary site of oxygen uptake while inflated. Despite this, post-deflation recovery of aerobic metabolism took an average of 5.6 h, suggesting a contribution of anaerobic metabolism during pre-inflation activity and during the act of ingesting water to achieve inflation. PMID:25472941

Multiphase CT scanning and different intravenous contrast media concentrations in combined F-18-FDG PET/CT: Effect on quantitative and clinical assessment.

PubMed

Rebière, Marilou; Verburg, Frederik A; Palmowski, Moritz; Krohn, Thomas; Pietsch, Hubertus; Kuhl, Christiane K; Mottaghy, Felix M; Behrendt, Florian F

2012-08-01

To evaluate the influence of multiphase CT scanning and different intravenous contrast media on contrast enhancement, attenuation correction and image quality in combined PET/CT. 140 patients were prospectively enrolled for F-18-FDG-PET/CT including a low-dose unenhanced, arterial and venous contrast enhanced CT. The first (second) 70 patients, received contrast medium with 370 (300) mg iodine/ml. The iodine delivery rate (1.3mg/s) and total iodine load (44.4g) were identical for both groups. Contrast enhancement and maximum and mean standardized FDG uptake values (SUVmax and SUVmean) were determined for the un-enhanced, arterial and venous PET/CT at multiple anatomic sites and PET reconstructions were visually evaluated. Arterial contrast enhancement was significantly higher for the 300mg/ml contrast medium compared to 370mgI/ml at all anatomic sites. Venous enhancement was not different between the two contrast media. SUVmean and SUVmax were significantly higher for the contrast enhanced compared to the non-enhanced PET/CT at all anatomic sites (all P<0.001). Tracer uptake was significantly higher in the arterial than in the venous PET/CT in the arteries using both contrast media (all P<0.001). No differences in tracer uptake were found between the contrast media (all P>0.05). Visual assessment revealed no relevant differences between the different PET reconstructions. There is no relevant qualitative influence on the PET scan from the use of different intravenous contrast media in its various phases in combined multiphase PET/CT. For quantitative analysis of tracer uptake it is required to use an identical PET/CT protocol. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Interactions between bacterial carbon monoxide and hydrogen consumption and plant development on recent volcanic deposits.

PubMed

King, Gary M; Weber, Carolyn F

2008-02-01

Patterns of microbial colonization and interactions between microbial processes and vascular plants on volcanic deposits have received little attention. Previous reports have shown that atmospheric CO and hydrogen contribute significantly to microbial metabolism on Kilauea volcano (Hawaii) deposits with varied ages and successional development. Relationships between CO oxidation and plant communities were not clear, however, since deposit age and vegetation status covaried. To determine plant-microbe interactions in deposits of uniform ages, CO and hydrogen dynamics have been assayed for unvegetated tephra on a 1959 deposit at Pu'u Puai (PP-bare), at the edge of tree 'islands' within the PP deposit (PP-edge) and within PP tree islands (PP-canopy). Similar assays have been conducted for vegetated and unvegetated sites on a 1969 Mauna Ulu (MU) lava flow. Net in situ atmospheric CO uptake was highest at PP-edge and PP-bare sites (2.2+/-0.5 and 1.3+/-0.1 mg CO m(-2) day(-1), respectively), and least for PP-canopy (-3.2+/-0.9 mg CO m(-2) day(-1), net emission). Respiration rates, microbial biomass and maximum CO uptake potential showed an opposing pattern. Comparisons of atmospheric CO uptake and CO(2) production rates indicate that CO contributes significantly to microbial metabolism in PP-bare and MU-unvegetated sites, but negligibly where vegetation is well developed. Nonetheless, maximum potential CO uptake rates indicate that CO oxidizer populations increase with increasing plant biomass and consume CO actively. Some of these CO oxidizers may contribute to elevated nitrogen fixation rates (acetylene reduction) measured within tree islands, and thus, support plant successional development.

Stoichiometry and kinetics of mercury uptake by photosynthetic bacteria.

PubMed

Kis, Mariann; Sipka, Gábor; Maróti, Péter

2017-05-01

Mercury adsorption on the cell surface and intracellular uptake by bacteria represent the key first step in the production and accumulation of highly toxic mercury in living organisms. In this work, the biophysical characteristics of mercury bioaccumulation are studied in intact cells of photosynthetic bacteria by use of analytical (dithizone) assay and physiological photosynthetic markers (pigment content, fluorescence induction, and membrane potential) to determine the amount of mercury ions bound to the cell surface and taken up by the cell. It is shown that the Hg(II) uptake mechanism (1) has two kinetically distinguishable components, (2) includes co-opted influx through heavy metal transporters since the slow component is inhibited by Ca 2+ channel blockers, (3) shows complex pH dependence demonstrating the competition of ligand binding of Hg(II) ions with H + ions (low pH) and high tendency of complex formation of Hg(II) with hydroxyl ions (high pH), and (4) is not a passive but an energy-dependent process as evidenced by light activation and inhibition by protonophore. Photosynthetic bacteria can accumulate Hg(II) in amounts much (about 10 5 ) greater than their own masses by well-defined strong and weak binding sites with equilibrium binding constants in the range of 1 (μM) -1 and 1 (mM) -1 , respectively. The strong binding sites are attributed to sulfhydryl groups as the uptake is blocked by use of sulfhydryl modifying agents and their number is much (two orders of magnitude) smaller than the number of weak binding sites. Biofilms developed by some bacteria (e.g., Rvx. gelatinosus) increase the mercury binding capacity further by a factor of about five. Photosynthetic bacteria in the light act as a sponge of Hg(II) and can be potentially used for biomonitoring and bioremediation of mercury-contaminated aqueous cultures.

Pretargeting of carcinoembryonic antigen-expressing cancers with a trivalent bispecific fusion protein produced in myeloma cells.

PubMed

Rossi, Edmund A; Chang, Chien-Hsing; Losman, Michele J; Sharkey, Robert M; Karacay, Habibe; McBride, William; Cardillo, Thomas M; Hansen, Hans J; Qu, Zhengxing; Horak, Ivan D; Goldenberg, David M

2005-10-01

To characterize a novel trivalent bispecific fusion protein and evaluate its potential utility for pretargeted delivery of radionuclides to tumors. hBS14, a recombinant fusion protein that binds bispecifically to carcinoembryonic antigen (CEA) and the hapten, histamine-succinyl-glycine (HSG), was produced by transgenic myeloma cells and purified to near homogeneity in a single step using a novel HSG-based affinity chromatography system. Biochemical characterization included size-exclusion high-performance liquid chromatography (SE-HPLC), SDS-PAGE, and isoelectric focusing. Functional characterization was provided by BIAcore and SE-HPLC. The efficacy of hBS14 for tumor pretargeting was evaluated in CEA-expressing GW-39 human colon tumor-bearing nude mice using a bivalent HSG hapten (IMP-241) labeled with (111)In. Biochemical analysis showed that single-step affinity chromatography provided highly purified material. SE-HPLC shows a single protein peak consistent with the predicted molecular size of hBS14. SDS-PAGE analysis shows only two polypeptide bands, which are consistent with the calculated molecular weights of the hBS14 polypeptides. BIAcore showed the bispecific binding properties and suggested that hBS14 possesses two functional CEA-binding sites. This was supported by SE-HPLC immunoreactivity experiments. All of the data suggest that the structure of hBS14 is an 80 kDa heterodimer with one HSG and two CEA binding sites. Pretargeting experiments in the mouse model showed high uptake of radiopeptide in the tumor, with favorable tumor-to-nontumor ratios as early as 3 hours postinjection. The results indicate that hBS14 is an attractive candidate for use in a variety of pretargeting applications, particularly tumor therapy with radionuclides and drugs.

Design and characterization of α-melanotropin peptide analogs cyclized through rhenium and technetium metal coordination

PubMed Central

Giblin, Michael F.; Wang, Nannan; Hoffman, Timothy J.; Jurisson, Silvia S.; Quinn, Thomas P.

1998-01-01

α-Melanocyte stimulating hormone (α-MSH) analogs, cyclized through site-specific rhenium (Re) and technetium (Tc) metal coordination, were structurally characterized and analyzed for their abilities to bind α-MSH receptors present on melanoma cells and in tumor-bearing mice. Results from receptor-binding assays conducted with B16 F1 murine melanoma cells indicated that receptor-binding affinity was reduced to approximately 1% of its original levels after Re incorporation into the cyclic Cys4,10, d-Phe7–α-MSH4-13 analog. Structural analysis of the Re–peptide complex showed that the disulfide bond of the original peptide was replaced by thiolate–metal–thiolate cyclization. A comparison of the metal-bound and metal-free structures indicated that metal complexation dramatically altered the structure of the receptor-binding core sequence. Redesign of the metal binding site resulted in a second-generation Re–peptide complex (ReCCMSH) that displayed a receptor-binding affinity of 2.9 nM, 25-fold higher than the initial Re–α-MSH analog. Characterization of the second-generation Re–peptide complex indicated that the peptide was still cyclized through Re coordination, but the structure of the receptor-binding sequence was no longer constrained. The corresponding 99mTc- and 188ReCCMSH complexes were synthesized and shown to be stable in phosphate-buffered saline and to challenges from diethylenetriaminepentaacetic acid (DTPA) and free cysteine. In vivo, the 99mTcCCMSH complex exhibited significant tumor uptake and retention and was effective in imaging melanoma in a murine-tumor model system. Cyclization of α-MSH analogs via 99mTc and 188Re yields chemically stable and biologically active molecules with potential melanoma-imaging and therapeutic properties. PMID:9788997

Follow-up bone scan in breast cancer patients: what is the appropriate interpretation of purely rib uptake?

PubMed

Seo, Minjung; Ko, Byung Kyun; Tae, Soon Young; Koh, Su-Jin; Noh, Young Ju; Choi, Hye-Jeong; Bae, Kyungkyg; Bang, Minseo; Jun, Sungmin; Park, Seol Hoon

2016-12-01

Although rib uptake is frequently detected in follow-up bone scans of breast cancer patients, few studies have assessed its clinical significance. Among 1208 breast cancer patients who underwent a bone scan between 2011 and 2014, 157 patients presented with newly detected rib uptake at follow-up. Patients who had underlying bone metastases (n=8) or had simultaneous new uptake in sites other than the rib (n=13) were excluded. The patients enrolled finally were those who had purely rib uptakes. The location, intensity, and final diagnosis of the uptake were evaluated by nuclear medicine physicians. A total of 275 new instances of rib uptake were detected in follow-up bone scans of 136 patients. These were more frequently located on the ipsilateral side of the breast cancer (61.1%) and the anterior arc (65.1%), and they presented as moderate to intense (93.1%) uptakes. Among these, 265 lesions in 130 patients turned out to be benign fractures (96.4%), whereas only 10 lesions in six patients were metastases. The proportion of metastases was significantly higher if the uptake was linear or if the patient had recurrence. It was marginally higher if the uptake was located in the posterior arc. The proportion of metastases within the radiation field was significantly lower in patients with a history of irradiation. Newly detected purely rib uptake on a follow-up bone scan in patients who have been treated for breast cancer is mostly because of fractures and rarely signals metastasis. However, if the patient has disease recurrence, metastasis should strongly be suspected, particularly when uptake is linear or located in the posterior arc.

Oxidative phosphorylation. The relation between the specific binding of trimethlytin and triethyltin to mitochondria and their effects on various mitochondrial functions

PubMed Central

Aldridge, W. N.; Street, B. W.

1971-01-01

1. A binding site (site 1) is present in mitochondria with affinity for trimethyltin and triethyltin adequate for a site to which they could be attached when the processes of energy conservation are inhibited. 2. The quantitative relationships between the binding of trimethyltin and triethyltin to site 1 and their effects on various mitochondrial functions have been examined. 3. ATP synthesis linked to the oxidation of pyruvate, succinate and intramitochondrial substrate, ATP synthesis and oxygen uptake (succinate or pyruvate as substrate) stimulated by uncoupling agents are all inhibited by trimethyltin and triethyltin; when inhibition is less than 50% the ratio (percentage inhibition)/(percentage of binding site 1 complexed) is approx. 10:1. 4. ATP synthesis linked to the oxidation of reduced cytochrome c (ascorbate+NNN′N′-tetramethyl-p-phenylenediamine), ATP hydrolysis and oxygen uptake in the presence of low concentrations of trimethyltin and triethyltin approach zero activity as the proportion of binding site 1 complexed approaches 100%. 5. Possible interpretations of these findings are discussed with reference to published arrangements for coupling of electron transport to ATP synthesis and also to our present knowledge of the chemical and biological specificity of trialkyltin compounds. PMID:5126473

The use of the brown macroalgae, Sargassum flavicans, as a potential bioindicator of industrial nutrient enrichment.

PubMed

Alquezar, Ralph; Glendenning, Lionel; Costanzo, Simon

2013-12-15

Nutrient bioindicators are increasingly being recognised as a diagnostic tool for nutrient enrichment of estuarine and marine ecosystems. Few studies, however, have focused on field translocation of bioindicator organisms to detect nutrient discharge from industrial waste. The brown macroalgae, Sargassum flavicans, was investigated as a potential bioindicator of nutrient-enriched industrial effluent originating from a nickel refinery in tropical north-eastern Australia. S. flavicans was translocated to a number of nutrient enriched creek and oceanic sites over two seasons and assessed for changes in stable isotope ratios of (15)N and (13)C within the plant tissue in comparison to reference sites. Nutrient uptake in macroalgae, translocated to the nutrient enriched sites adjacent to the refinery, increased 3-4-fold in δ(15)N, compared to reference sites. Using δ(15)N of translocated S. flavicans proved to be a successful method for monitoring time-integrated uptake of nitrogen, given the current lack of passive sampler technology for nutrient monitoring. Copyright © 2013 Elsevier Ltd. All rights reserved.

Characterization of Avt1p as a vacuolar proton/amino acid antiporter in Saccharomyces cerevisiae.

PubMed

Tone, Junichi; Yoshimura, Ayumi; Manabe, Kunio; Murao, Nami; Sekito, Takayuki; Kawano-Kawada, Miyuki; Kakinuma, Yoshimi

2015-01-01

Several genes for vacuolar amino acid transport were reported in Saccharomyces cerevisiae, but have not well been investigated. We characterized AVT1, a member of the AVT vacuolar transporter family, which is reported to be involved in lifespan of yeast. ATP-dependent uptake of isoleucine and histidine by the vacuolar vesicles of an AVT exporter mutant was lost by introducing avt1∆ mutation. Uptake activity was inhibited by the V-ATPase inhibitor: concanamycin A and a protonophore. Isoleucine uptake was inhibited by various neutral amino acids and histidine, but not by γ-aminobutyric acid, glutamate, and aspartate. V-ATPase-dependent acidification of the vesicles was declined by the addition of isoleucine or histidine, depending upon Avt1p. Taken together with the data of the amino acid contents of vacuolar fractions in cells, the results suggested that Avt1p is a proton/amino acid antiporter important for vacuolar compartmentalization of various amino acids.

AF64A depletes hippocampal high-affinity choline uptake but does not alter the density of alpha-bungarotoxin binding sites or modify the effect of exogenous choline.

PubMed

Morley, B J; Garner, L L

1990-06-11

Sodium-dependent, high-affinity choline uptake (HACU) and the density of alpha-bungarotoxin (BuTX) receptor-binding sites were measured in the hippocampus following the intraventricular infusion of ethylcholine aziridinium ion (AF64A), a neurotoxin that competes with choline at high-affinity choline transport sites and may result in the degeneration of cholinergic axons. Eight days after the infusion of AF64A into the lateral ventricles (2.5 nmol/side), HACU was depleted by 60% in the hippocampus of experimental animals in comparison with controls, but the density of BuTX-binding sites was not altered. The administration of 15 mg/ml of choline chloride in the drinking water increased the density of BuTX-binding sites, as previously reported by this laboratory. The administration of AF64A did not prevent the effect of exogenous choline on the density of binding sites, nor did choline treatment alter the effect of AF64A on HACU. These data indicate that the density of BuTX-binding sites in the hippocampus is not altered following a substantial decrease in HACU and presumed degeneration of cholinergic axons. Since the effect of exogenous choline was not prevented by AF64A treatment, the data are interpreted to support the hypothesis that the increase in the density of BuTX-binding sites following dietary choline supplementation is attributable to a direct effect of choline on receptor sites.

Old and Not-So-Old: Examining Changes in Forest Ecosystem Carbon Exchange With Stand Age in the Upper Midwest U.S.

NASA Astrophysics Data System (ADS)

Desai, A. R.; Cook, B.; Davis, K. J.; Bolstad, P.; Carey, E.; Martin, J.; Kreller, L.; Wang, W.

2003-12-01

Forest stand age is an important determinant of ecosystem carbon uptake. Though there are biometric measurements and ecological models for forests of all ages, there are few stand-scale eddy-flux measurements of net carbon exchange in older forests, though the number is increasing. In order to scale carbon fluxes from sites to regions, where stands of multiple ages may exist, it is necessary to measure to the effect of stand age on carbon exchange. Measuring the effect of stand age on carbon exchange is also necessary when trying to predict future or past carbon exchange (scaling across time). Many researchers have noted that site disturbance history is the fundamental factor in determining carbon uptake by forests over time scales of decades to centuries. The 8,500 ha Sylvania Wilderness in the upper peninsula of Michigan is one of several large tracts of old-growth forest in the Midwest. Trees range from 0-350 years old. Primary species are sugar maple, eastern hemlock and yellow birch. Catastrophic disturbance is rare. A research plot near the wilderness was established in late 2001 to measure the net ecosystem exchange (NEE) of carbon and water using eddy-flux, component flux and biometric methods. This site is part of the Chequamegon Ecosystem Atmosphere Study (ChEAS, http://cheas.psu.edu), a loose affiliation of researchers conducting carbon and water research in northern Wisconsin and upper Michigan. Another similar research plot within ChEAS and not far from Sylvania is the Willow Creek mature uplands site. This forest is about 70 years old and the primary species are sugar maple, basswood and green ash. The site had presettlement old-growth vegetation similar to what is currently seen in the Sylvania Wilderness. Thus, the carbon exchange seen at Sylvania may be representative of carbon uptake at Willow Creek had it not been logged in the early 20th century, and may also represent the future (or past) carbon uptake for similar forests in northern Wisconsin/upper Michigan. Initial results from 2002 show that both Sylvania and Willow Creek were sinks of carbon, though the annual NEE of carbon at Sylvania was only -72 gC/m2/yr, while it was -447 gC/m2/yr at Willow Creek. The lack of carbon balance at the old-growth site may be caused by growth enhancement due to carbon/nutrient fertilization, climate warming, or recent local-scale disturbances. A standard moving-window Arrenhius-style temperature-nighttime NEE relationship was used to separate total ecosystem respiration from gross ecosystem production (GEP). Total annual respiration was much greater at Sylvania (965 gC/m2/yr) than Willow Creek (667 gC/m2/yr), while GEP at Sylvania (1045 gC/m2/yr) was only slightly smaller than Willow Creek (1136 gC/m2/yr). The largest differences in respiration between the two sites occurred in early summer, whereas the largest difference in GEP occurred in late summer. The observed differences between the two sites matches well with theory. Ecosystem respiration is expected to increase steadily with stand age while gross ecosystem production is expected to increase rapidly as new species are established, but eventually level off. Current ongoing component flux measurements will help determine the mechanisms for the observed differences in carbon uptake at the two sites and provide insight on the causes of declining carbon exchange with stand age.

Uncovering the transmembrane metal binding site of the novel bacterial major facilitator superfamily-type copper importer CcoA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khalfaoui-Hassani, Bahia; Verissimo, Andreia F.; Koch, Hans -Georg

In this study, uptake and trafficking of metals and their delivery to their respective metalloproteins are important processes. Cells need precise control of each step to avoid exposure to excessive metal concentrations and their harmful consequences. Copper (Cu) is a required micronutrient used as a cofactor in proteins. However, in large amounts, it can induce oxidative damage; hence, Cu homeostasis is indispensable for cell survival. Biogenesis of respiratory heme-Cu oxygen (HCO) reductases includes insertion of Cu into their catalytic subunits to form heme-Cu binuclear centers. Previously, we had shown that CcoA is a major facilitator superfamily (MFS)-type bacterial Cu importermore » required for biogenesis of cbb 3-type cytochrome coxidase ( cbb 3-Cox). Here, using Rhodobacter capsulatus, we focused on the import and delivery of Cu to cbb 3-Cox. By comparing the CcoA amino acid sequence with its homologues from other bacterial species, we located several well-conserved Met, His, and Tyr residues that might be important for Cu transport. We determined the topology of the transmembrane helices that carry these residues to establish that they are membrane embedded, and substituted for them amino acids that do not ligand metal atoms. Characterization of these mutants for their uptake of radioactive 64Cu and cbb 3-Cox activities demonstrated that Met233 and His261 of CcoA are essential and Met237 and Met265 are important, whereas Tyr230 has no role for Cu uptake or cbb3-Cox biogenesis. These findings show for the first time that CcoA-mediated Cu import relies on conserved Met and His residues that could act as metal ligands at the membrane-embedded Cu binding domain of this transporter.« less

Nuclear delivery of a therapeutic peptide by long circulating pH-sensitive liposomes: benefits over classical vesicles.

PubMed

Ducat, E; Deprez, J; Gillet, A; Noël, A; Evrard, B; Peulen, O; Piel, G

2011-11-28

The purpose of this study is to propose a suitable vector combining increased circulation lifetime and intracellular delivery capacities for a therapeutic peptide. Long circulating classical liposomes [SPC:CHOL:PEG-750-DSPE (47:47:6 molar% ratio)] or pH-sensitive stealth liposomes [DOPE:CHEMS:CHOL:PEG(750)-DSPE (43:21:30:6 molar% ratio)] were used to deliver a therapeutic peptide to its nuclear site of action. The benefit of using stealth pH-sensitive liposomes was investigated and formulations were compared to classical liposomes in terms of size, shape, charge, encapsulation efficiency, stability and, most importantly, in terms of cellular uptake. Confocal microscopy and flow cytometry were used to evaluate the intracellular fate of liposomes themselves and of their hydrophilic encapsulated material. Cellular uptake of peptide-loaded liposomes was also investigated in three cell lines: Hs578t human epithelial cells from breast carcinoma, MDA-MB-231 human breast carcinoma cells and WI-26 human diploid lung fibroblast cells. The difference between formulations in terms of peptide delivery from the endosome to the cytoplasm and even to the nucleus was investigated as a function of time. Characterization studies showed that both formulations possess acceptable size, shape and encapsulation efficiency but cellular uptake studies showed the important benefit of the pH-sensitive formulation over the classical one, in spite of liposome PEGylation. Indeed, stealth pH-sensitive liposomes were able to deliver hydrophilic materials strongly to the cytoplasm. Most importantly, when encapsulated in pH-sensitive stealth liposomes, the peptide was able to reach the nucleus of tumorigenic and non tumorigenic breast cancer cells. Copyright © 2011 Elsevier B.V. All rights reserved.

Are health interventions implemented where they are most needed? District uptake of the integrated management of childhood illness strategy in Brazil, Peru and the United Republic of Tanzania.

PubMed Central

Victora, C. G.; Huicho, L.; Amaral, J. J.; Armstrong-Schellenberg, J.; Manzi, F.; Mason, E.; Scherpbier, R.

2006-01-01

OBJECTIVE: To describe geographical patterns of implementation of the Integrated Management of Childhood Illness (IMCI) strategy in three countries and to assess whether the strategy was implemented in areas with the most pressing child health needs. METHODS: We conducted interviews with key informants at the national and district levels in Brazil, Peru and the United Republic of Tanzania, and an ecological study of factors associated with health worker training in IMCI. Explanatory factors included district population, distance from the capital, human development index, other socioeconomic indicators and baseline mortality rates in children younger than five years. FINDINGS: In line with recommendations by WHO, early implementation districts were characterized by proximity to the capital and suitable training sites, presence of motivated health managers and a functioning health system. In the expansion phase, IMCI tended to be adopted by other districts with similar characteristics. In Brazil, uptake by poor and small municipalities and those further away from the state capital was significantly lower. In Peru, there was no association with distance from Lima, and a non-significant trend for IMCI adoption by small and poor departments. In the United Republic of Tanzania, the only statistically significant finding was a lower uptake by remote districts. Implementation was not associated with baseline mortality levels in any country studied. CONCLUSION: Whereas clear and reasonable guidelines are provided for selection of early use districts, no criteria for promoting IMCI expansion had been issued, and areas of greatest need were not prioritized. Equity analyses based on the geographical deployment of new programmes and strategies can contribute to assessing whether they are reaching those who need them most. PMID:17128359

Pharmacological characterization of ecstasy synthesis byproducts with recombinant human monoamine transporters.

PubMed

Pifl, Christian; Nagy, Gabor; Berényi, Sándor; Kattinger, Alexandra; Reither, Harald; Antus, Sándor

2005-07-01

Ecstasy samples often contain byproducts of the illegal, uncontrolled synthesis of N-methyl-3,4-methylenedioxy-amphetamine or 3,4-methylenedioxymethamphetamine (MDMA). MDMA and eight chemically defined byproducts of MDMA synthesis were investigated for their interaction with the primary sites of action of MDMA, namely the human plasmalemmal monamine transporters for norepinephrine, serotonin, and dopamine [(norepinephrine transporter (NET), serotonin transporter (SERT), and dopamine transporter (DAT)]. SK-N-MC neuroblastoma and human embryonic kidney cells stably transfected with the transporter cDNA were used for uptake and release experiments. Two of the eight compounds, 1,3-bis (3,4-methylenedioxyphenyl)-2-propanamine (12) and N-formyl-1,3-bis (3,4-methylenedioxyphenyl)-prop-2-yl-amine (13) had uptake inhibitory potencies with IC50 values in the low micromolar range similar to MDMA. Compounds with nitro instead of amino groups and a phenylethenyl instead of a phenylethyl structure or a formamide or acetamide modification had IC50 values beyond 100 microM. MDMA, 12, and 13 were examined for induction of carrier-mediated release by superfusion of transporter expressing cells preloaded with the metabolically inert transporter substrate [3H]1-methyl-4-phenylpyridinium. MDMA induced release mediated by NET, SERT, or DAT with EC50 values of 0.64, 1.12, and 3.24 microM, respectively. 12 weakly released from NET- and SERT-expressing cells with maximum effects less than one-tenth of that of MDMA and did not release from DAT cells. 13 had no releasing activity. 12 and 13 inhibited release induced by MDMA, and the concentration dependence of this effect correlated with their uptake inhibitory potency at the various transporters. These results do not support a neurotoxic potential of the examined ecstasy synthesis byproducts and provide interesting structure-activity relationships on the transporters.

Uncovering the transmembrane metal binding site of the novel bacterial major facilitator superfamily-type copper importer CcoA

DOE PAGES

Khalfaoui-Hassani, Bahia; Verissimo, Andreia F.; Koch, Hans -Georg; ...

2016-01-19

In this study, uptake and trafficking of metals and their delivery to their respective metalloproteins are important processes. Cells need precise control of each step to avoid exposure to excessive metal concentrations and their harmful consequences. Copper (Cu) is a required micronutrient used as a cofactor in proteins. However, in large amounts, it can induce oxidative damage; hence, Cu homeostasis is indispensable for cell survival. Biogenesis of respiratory heme-Cu oxygen (HCO) reductases includes insertion of Cu into their catalytic subunits to form heme-Cu binuclear centers. Previously, we had shown that CcoA is a major facilitator superfamily (MFS)-type bacterial Cu importermore » required for biogenesis of cbb 3-type cytochrome coxidase ( cbb 3-Cox). Here, using Rhodobacter capsulatus, we focused on the import and delivery of Cu to cbb 3-Cox. By comparing the CcoA amino acid sequence with its homologues from other bacterial species, we located several well-conserved Met, His, and Tyr residues that might be important for Cu transport. We determined the topology of the transmembrane helices that carry these residues to establish that they are membrane embedded, and substituted for them amino acids that do not ligand metal atoms. Characterization of these mutants for their uptake of radioactive 64Cu and cbb 3-Cox activities demonstrated that Met233 and His261 of CcoA are essential and Met237 and Met265 are important, whereas Tyr230 has no role for Cu uptake or cbb3-Cox biogenesis. These findings show for the first time that CcoA-mediated Cu import relies on conserved Met and His residues that could act as metal ligands at the membrane-embedded Cu binding domain of this transporter.« less

Uptake of carbamazepine by rhizomes and endophytic bacteria of Phragmites australis

PubMed Central

Sauvêtre, Andrés; Schröder, Peter

2015-01-01

Carbamazepine is an antiepileptic and mood-stabilizing drug which is used widely in Europe and North America. In the environment, it is found as a persistent and recalcitrant contaminant, being one of the most prominent hazardous pharmaceuticals and personal care products in effluents of wastewater treatment plants. Phragmites australis is one of the species with both, the highest potential of detoxification and phytoremediation. It has been used successfully in the treatment of industrial and municipal wastewater. Recently, the identification of endophytic microorganisms from different plant species growing in contaminated sites has provided a list of candidates which could be used as bio-inoculants for bioremediation of difficult compounds. In this study, Phragmites australis plants were exposed to 5 mg/L of carbamazepine. After 9 days the plants had removed 90% of the initial concentration. Endophytic bacteria were isolated from these plants and further characterized. Phylogenetic analysis based on 16S rDNA sequencing revealed that the majority of these isolates belong to three groups: Proteobacteria, Actinobacteria, and Bacteroidetes. Carbamazepine uptake and plant growth promoting (PGP) traits were analyzed among the isolates. Ninety percent of the isolates produce indole acetic acid (IAA) and all of them possess at least one of the PGP traits tested. One isolate identified as Chryseobacterium taeanense combines good carbamazepine uptake and all of the PGP traits. Rhizobium daejeonense can remove carbamazepine and produces 23 μg/mL of IAA. Diaphorobacter nitroreducens and Achromobacter mucicolens are suitable for carbamazepine removal while both, Pseudomonas veronii and Pseudomonas lini show high siderophore production and phosphate solubilization. Alone or in combination, these isolates might be applied as inoculates in constructed wetlands in order to enhance the phytoremediation of carbamazepine during wastewater treatment. PMID:25750647

Anatomic Site Variability in Rat Skeletal Uptake and Desorption Of Fluorescently Labeled Bisphosphonate

PubMed Central

Wen, D.; Qing, L.; Harrison, G.; Golub, E.; Akintoye, S.O.

2010-01-01

Objectives Bisphosphonates commonly used to treat osteoporosis, Paget’s disease, multiple myeloma, hypercalcemia of malignancy and osteolytic lesions of cancer metastasis have been associated with bisphosphonate-associated jaw osteonecrosis (BJON). The underlying pathogenesis of BJON is unclear, but disproportionate bisphosphonate concentration in the jaw has been proposed as one potential etiological factor. This study tested the hypothesis that skeletal biodistribution of intravenous bisphosphonate is anatomic site-dependent in a rat model system. Materials and Methods Fluorescently labeled pamidronate was injected intravenously in athymic rats of equal weights followed by in vivo whole body fluorimetry, ex vivo optical imaging of oral, axial and appendicular bones and ethylenediaminetetraacetic acid bone decalcification to assess hydroxyapatite-bound bisphosphonate. Results Bisphosphonate uptake and bisphosphonate released per unit calcium were similar in oral and appendicular bones but lower than those in axial bones. Hydroxyapatite-bound bisphosphonate liberated by sequential acid decalcification was highest in oral relative to axial and appendicular bones (p < 0.05). Conclusions This study demonstrates regional differences in uptake and release of bisphosphonate from oral, axial and appendicular bones of immune deficient rats. PMID:21122034

Influence of Prolonged Spaceflight on Heart Rate and Oxygen Uptake Kinetics

NASA Astrophysics Data System (ADS)

Hoffmann, U.; Moore, A.; Drescher, U.

2013-02-01

During prolonged spaceflight, physical training is used to minimize cardiovascular deconditioning. Measurement of the kinetics of cardiorespiratory parameters, in particular the kinetic analysis of heart rate, respiratory and muscular oxygen uptake, provides useful information with regard to the efficiency and regulation of the cardiorespiratory system. Practically, oxygen uptake kinetics can only be measured at the lung site (V’O2 resp). The dynamics of V’O2 resp, however, is not identical with the dynamics at the site of interest: skeletal muscle. Eight Astronauts were tested pre- and post-flight using pseudo random binary workload changes between 30 and 80 W. Their kinetic responses of heart rate, respiratory as well as muscular V’O2 kinetics were estimated by using time-series analysis. Statistical analysis revealed that the kinetic responses of respiratory as well as muscular V’O2 kinetics are slowed post-flight than pre-flight. Heart rate seems not to be influenced following flight. The influence of other factors (e. g. astronauts’ exercise training) may impact these parameters and is an area for future studies.

AUX1 regulates root gravitropism in Arabidopsis by facilitating auxin uptake within root apical tissues.

PubMed Central

Marchant, A; Kargul, J; May, S T; Muller, P; Delbarre, A; Perrot-Rechenmann, C; Bennett, M J

1999-01-01

Plants employ a specialized transport system composed of separate influx and efflux carriers to mobilize the plant hormone auxin between its site(s) of synthesis and action. Mutations within the permease-like AUX1 protein significantly reduce the rate of carrier-mediated auxin uptake within Arabidopsis roots, conferring an agravitropic phenotype. We are able to bypass the defect within auxin uptake and restore the gravitropic root phenotype of aux1 by growing mutant seedlings in the presence of the membrane-permeable synthetic auxin, 1-naphthaleneacetic acid. We illustrate that AUX1 expression overlaps that previously described for the auxin efflux carrier, AtPIN2, using transgenic lines expressing an AUX1 promoter::uidA (GUS) gene. Finally, we demonstrate that AUX1 regulates gravitropic curvature by acting in unison with the auxin efflux carrier to co-ordinate the localized redistribution of auxin within the Arabidopsis root apex. Our results provide the first example of a developmental role for the auxin influx carrier within higher plants and supply new insight into the molecular basis of gravitropic signalling. PMID:10205161

Contaminated groundwater characterization at the Chalk River Laboratories, Ontario, Canada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schilk, A.J.; Robertson, D.E.; Thomas, C.W.

1993-03-01

The licensing requirements for the disposal of low-level radioactive waste (10 CFR 61) specify the performance objectives and technical requisites for federal and commercial land disposal facilities, the ultimate goal of which is to contain the buried wastes so that the general population is adequately protected from harmful exposure to any released radioactive materials. A major concern in the operation of existing and projected waste disposal sites is subterranean radionuclide transport by saturated or unsaturated flow, which could lead to the contamination of groundwater systems as well as uptake by the surrounding biosphere, thereby directly exposing the general public tomore » such materials. Radionuclide transport in groundwater has been observed at numerous commercial and federal waste disposal sites [including several locations within the waste management area of Chalk River Laboratories (CRL)], yet the physico-chemical processes that lead to such migration are still not completely understood. In an attempt to assist in the characterization of these processes, an intensive study was initiated at CRL to identify and quantify the mobile radionuclide species originating from three separate disposal sites: (a) the Chemical Pit, which has received aqueous wastes containing various radioisotopes, acids, alkalis, complexing agents and salts since 1956, (b) the Reactor Pit, which has received low-level aqueous wastes from a reactor rod storage bay since 1956, and (c) the Waste Management Area C, a thirty-year-old series of trenches that contains contaminated solid wastes from CRL and various regional medical facilities. Water samples were drawn downgradient from each of the above sites and passed through a series of filters and ion-exchange resins to retain any particulate and dissolved or colloidal radionuclide species, which were subsequently identified and quantified via radiochemical separations and gamma spectroscopy. These groundwaters were also analyzed for anions, trace metals, Eh, pH, alkalinity and dissolved oxygen.« less

Pharmacological characterization of the voltage-dependent Ca2+ channels present in synaptosomes from rat and chicken central nervous system.

PubMed

Alvarez Maubecin, V; Sanchez, V N; Rosato Siri, M D; Cherksey, B D; Sugimori, M; Llinás, R; Uchitel, O D

1995-06-01

The voltage-dependent calcium channels present in mammalian and chicken brain synaptosomes were characterized pharmacologically using specific blockers of L-type channels (1,4-dihydropyridines), N-type channels (omega-conotoxin GVIA), and P-type channels [funnel web toxin (FTX) and omega-agatoxin IVA]. K(+)-induced Ca2+ uptake by chicken synaptosomes was blocked by omega-conotoxin GVIA (IC50 = 250 nM). This toxin at 5 microM did not block Ca2+ entry into rat frontal cortex synaptosomes. FTX and omega-agatoxin IVA blocked Ca2+ uptake by rat synaptosomes (IC50 = 0.17 microliter/ml and 40 nM, respectively). Likewise, in chicken synaptosomes, FTX and omega-agatoxin IVA affected Ca2+ uptake, FTX (3 microliters/ml) exerted a maximal inhibition of 40% with an IC50 similar to the one obtained in rat preparations, whereas with omega-agatoxin IVA saturation was not reached even at 5 microM. In chicken preparations, the combined effect of saturating concentrations of FTX (1 microliter/ml) and different concentrations of omega-conotoxin GVIA showed no additive effects. However, the effect of saturating concentrations of FTX and omega-conotoxin GVIA was never greater than the one observed with omega-conotoxin GVIA. We also found that 60% of the Ca2+ uptake by rat and chicken synaptosomes was inhibited by omega-conotoxin MVIID (1 microM), a toxin that has a high index of discrimination against N-type channels. Conversely, nitrendipine (10 microM) had no significant effect on Ca2+ uptake in either the rat or the chicken. In conclusion, Ca2+ uptake by rat synaptosomes is potently inhibited by different P-type Ca2+ channel blockers, thus indicating that P-type channels are predominant in this preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Reserpine-induced Reduction in Norepinephrine Transporter Function Requires Catecholamine Storage Vesicles

PubMed Central

Mandela, Prashant; Chandley, Michelle; Xu, Yao-Yu; Zhu, Meng-Yang; Ordway, Gregory A.

2010-01-01

Treatment of rats with reserpine, an inhibitor of the vesicular monoamine transporter (VMAT), depletes norepinephrine (NE) and regulates NE transporter (NET) expression. The present study examined the molecular mechanisms involved in regulation of the NET by reserpine using cultured cells. Exposure of rat PC12 cells to reserpine for a period as short as 5 min decreased [3H]NE uptake capacity, an effect characterized by a robust decrease in the Vmax of the transport of [3H]NE. As expected, reserpine did not displace the binding of [3H]nisoxetine from the NET in membrane homogenates. The potency of reserpine for reducing [3H]NE uptake was dramatically lower in SK-N-SH cells that have reduced storage capacity for catecholamines. Reserpine had no effect on [3H]NE uptake in HEK-293 cells transfected with the rat NET (293-hNET), cells that lack catecholamine storage vesicles. NET regulation by reserpine was independent of trafficking of the NET from the cell surface. Pre-exposure of cells to inhibitors of several intracellular signaling cascades known to regulate the NET, including Ca2+/Ca2+-calmodulin dependent kinase and protein kinases A, C and G, did not affect the ability of reserpine to reduce [3H]NE uptake. Treatment of PC12 cells with the catecholamine depleting agent, α-methyl-p-tyrosine, increased [3H]NE uptake and eliminated the inhibitory effects of reserpine on [3H]NE uptake. Reserpine non-competitively inhibits NET activity through a Ca2+-independent process that requires catecholamine storage vesicles, revealing a novel pharmacological method to modify NET function. Further characterization of the molecular nature of reserpine's action could lead to the development of alternative therapeutic strategies for treating disorders known to be benefitted by treatment with traditional competitive NET inhibitors. PMID:20176067

Estimating uncertainty in ambient and saturation nutrient uptake metrics from nutrient pulse releases in stream ecosystems

DOE PAGES

Brooks, Scott C.; Brandt, Craig C.; Griffiths, Natalie A.

2016-10-07

Nutrient spiraling is an important ecosystem process characterizing nutrient transport and uptake in streams. Various nutrient addition methods are used to estimate uptake metrics; however, uncertainty in the metrics is not often evaluated. A method was developed to quantify uncertainty in ambient and saturation nutrient uptake metrics estimated from saturating pulse nutrient additions (Tracer Additions for Spiraling Curve Characterization; TASCC). Using a Monte Carlo (MC) approach, the 95% confidence interval (CI) was estimated for ambient uptake lengths (S w-amb) and maximum areal uptake rates (U max) based on 100,000 datasets generated from each of four nitrogen and five phosphorous TASCCmore » experiments conducted seasonally in a forest stream in eastern Tennessee, U.S.A. Uncertainty estimates from the MC approach were compared to the CIs estimated from ordinary least squares (OLS) and non-linear least squares (NLS) models used to calculate S w-amb and U max, respectively, from the TASCC method. The CIs for Sw-amb and Umax were large, but were not consistently larger using the MC method. Despite the large CIs, significant differences (based on nonoverlapping CIs) in nutrient metrics among seasons were found with more significant differences using the OLS/NLS vs. the MC method. Lastly, we suggest that the MC approach is a robust way to estimate uncertainty, as the calculation of S w-amb and U max violates assumptions of OLS/NLS while the MC approach is free of these assumptions. The MC approach can be applied to other ecosystem metrics that are calculated from multiple parameters, providing a more robust estimate of these metrics and their associated uncertainties.« less

Estimating uncertainty in ambient and saturation nutrient uptake metrics from nutrient pulse releases in stream ecosystems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brooks, Scott C.; Brandt, Craig C.; Griffiths, Natalie A.

Nutrient spiraling is an important ecosystem process characterizing nutrient transport and uptake in streams. Various nutrient addition methods are used to estimate uptake metrics; however, uncertainty in the metrics is not often evaluated. A method was developed to quantify uncertainty in ambient and saturation nutrient uptake metrics estimated from saturating pulse nutrient additions (Tracer Additions for Spiraling Curve Characterization; TASCC). Using a Monte Carlo (MC) approach, the 95% confidence interval (CI) was estimated for ambient uptake lengths (S w-amb) and maximum areal uptake rates (U max) based on 100,000 datasets generated from each of four nitrogen and five phosphorous TASCCmore » experiments conducted seasonally in a forest stream in eastern Tennessee, U.S.A. Uncertainty estimates from the MC approach were compared to the CIs estimated from ordinary least squares (OLS) and non-linear least squares (NLS) models used to calculate S w-amb and U max, respectively, from the TASCC method. The CIs for Sw-amb and Umax were large, but were not consistently larger using the MC method. Despite the large CIs, significant differences (based on nonoverlapping CIs) in nutrient metrics among seasons were found with more significant differences using the OLS/NLS vs. the MC method. Lastly, we suggest that the MC approach is a robust way to estimate uncertainty, as the calculation of S w-amb and U max violates assumptions of OLS/NLS while the MC approach is free of these assumptions. The MC approach can be applied to other ecosystem metrics that are calculated from multiple parameters, providing a more robust estimate of these metrics and their associated uncertainties.« less

Continuous measurements of methane flux in two Japanese temperate forests based on the micrometeorological and chamber methods

NASA Astrophysics Data System (ADS)

Yoshikawa, K.; Ueyama, M.; Takagi, K.; Kominami, Y.

2015-12-01

Methane (CH4) budget in forest ecosystems have not been accurately quantified due to limited measurements and considerable spatiotemporal heterogeneity. In order to quantify CH4 fluxes at temperate forest at various spatiotemporal scales, we have continuously measured CH4 fluxes at two upland forests based on the micrometeorological hyperbolic relaxed eddy accumulation (HREA) and automated dynamic closed chamber methods.The measurements have been conducted at Teshio experimental forest (TSE) since September 2013 and Yamashiro forest meteorology research site (YMS) since November 2014. Three automated chambers were installed on each site. Our system can measure CH4 flux by the micrometeorological HREA, vertical concentration profile at four heights, and chamber measurements by a laser-based gas analyzer (FGGA-24r-EP, Los Gatos Research Inc., USA).Seasonal variations of canopy-scale CH4 fluxes were different in each site. CH4 was consumed during the summer, but was emitted during the fall and winter in TSE; consequently, the site acted as a net annual CH4 source. CH4 was steadily consumed during the winter, but CH4 fluxes fluctuated between absorption and emission during the spring and summer in YMS. YMS acted as a net annual CH4 sink. CH4 uptake at the canopy scale generally decreased with rising soil temperature and increased with drying condition for both sites. CH4 flux measured by most of chambers showed the consistent sensitivity examined for the canopy scale to the environmental variables. CH4 fluxes from a few chambers located at a wet condition were independent of variations in soil temperature and moisture at both sites. Magnitude of soil CH4 uptake was higher than the canopy-scale CH4 uptake. Our results showed that the canopy-scale CH4 fluxes were totally different with the plot-scale CH4 fluxes by chambers, suggesting the considerable spatial heterogeneity in CH4 flux at the temperate forests.

Use of natural clays as sorbent materials for rare earth ions: Materials characterization and set up of the operative parameters.

PubMed

Iannicelli-Zubiani, Elena Maria; Cristiani, Cinzia; Dotelli, Giovanni; Gallo Stampino, Paola; Pelosato, Renato; Mesto, Ernesto; Schingaro, Emanuela; Lacalamita, Maria

2015-12-01

Two mineral clays of the montmorillonite group were tested as sorbents for the removal of Rare Earths (REs) from liquid solutions. Lanthanum and neodymium model solutions were used to perform uptake tests in order to: (a) verify the clays sorption capability, (b) investigate the sorption mechanisms and (c) optimize the experimental parameters, such as contact time and pH. The desorption was also studied, in order to evaluate the feasibility of REs recovery from waters. The adsorption-desorption procedure with the optimized parameters was also tested on a leaching solution obtained by dissolution of a dismantled NdFeB magnet of a hard-disk. The clays were fully characterized after REs adsorption and desorption by means of X-ray powder diffraction (XRPD) and X-ray photoelectron spectroscopy (XPS); the liquid phase was characterized via Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) analyses. The experimental results show that both clays are able to capture and release La and Nd ions, with an ion exchange mechanism. The best total efficiency (capture ≈ 50%, release ≈ 70%) is obtained when the uptake and release processes are performed at pH=5 and pH=1 respectively; in real leached scrap solutions, the uptake is around 40% but release efficiency is strongly decreased passing from a mono-ion system to a real system (from 80% to 5%). Furthermore, a strong matrix effect is found, with the matrix largely affecting both the uptake and the release of neodymium. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nicotine transport in lung and non-lung epithelial cells.

PubMed

Takano, Mikihisa; Kamei, Hidetaka; Nagahiro, Machi; Kawami, Masashi; Yumoto, Ryoko

2017-11-01

Nicotine is rapidly absorbed from the lung alveoli into systemic circulation during cigarette smoking. However, mechanism underlying nicotine transport in alveolar epithelial cells is not well understood to date. In the present study, we characterized nicotine uptake in lung epithelial cell lines A549 and NCI-H441 and in non-lung epithelial cell lines HepG2 and MCF-7. Characteristics of [ 3 H]nicotine uptake was studied using these cell lines. Nicotine uptake in A549 cells occurred in a time- and temperature-dependent manner and showed saturation kinetics, with a Km value of 0.31mM. Treatment with some organic cations such as diphenhydramine and pyrilamine inhibited nicotine uptake, whereas treatment with organic cations such as carnitine and tetraethylammonium did not affect nicotine uptake. Extracellular pH markedly affected nicotine uptake, with high nicotine uptake being observed at high pH up to 11.0. Modulation of intracellular pH with ammonium chloride also affected nicotine uptake. Treatment with valinomycin, a potassium ionophore, did not significantly affect nicotine uptake, indicating that nicotine uptake is an electroneutral process. For comparison, we assessed the characteristics of nicotine uptake in another lung epithelial cell line NCI-H441 and in non-lung epithelial cell lines HepG2 and MCF-7. Interestingly, these cell lines showed similar characteristics of nicotine uptake with respect to pH dependency and inhibition by various organic cations. The present findings suggest that a similar or the same pH-dependent transport system is involved in nicotine uptake in these cell lines. A novel molecular mechanism of nicotine transport is proposed. Copyright © 2017 Elsevier Inc. All rights reserved.

Radioluminescence Microscopy: Measuring the Heterogeneous Uptake of Radiotracers in Single Living Cells

PubMed Central

Pratx, Guillem; Chen, Kai; Sun, Conroy; Martin, Lynn; Carpenter, Colin M.; Olcott, Peter D.; Xing, Lei

2012-01-01

Radiotracers play an important role in interrogating molecular processes both in vitro and in vivo. However, current methods are limited to measuring average radiotracer uptake in large cell populations and, as a result, lack the ability to quantify cell-to-cell variations. Here we apply a new technique, termed radioluminescence microscopy, to visualize radiotracer uptake in single living cells, in a standard fluorescence microscopy environment. In this technique, live cells are cultured sparsely on a thin scintillator plate and incubated with a radiotracer. Light produced following beta decay is measured using a highly sensitive microscope. Radioluminescence microscopy revealed strong heterogeneity in the uptake of [18F]fluoro-deoxyglucose (FDG) in single cells, which was found consistent with fluorescence imaging of a glucose analog. We also verified that dynamic uptake of FDG in single cells followed the standard two-tissue compartmental model. Last, we transfected cells with a fusion PET/fluorescence reporter gene and found that uptake of FHBG (a PET radiotracer for transgene expression) coincided with expression of the fluorescent protein. Together, these results indicate that radioluminescence microscopy can visualize radiotracer uptake with single-cell resolution, which may find a use in the precise characterization of radiotracers. PMID:23056276

Roles of sulfuric acid in elemental mercury removal by activated carbon and sulfur-impregnated activated carbon.

PubMed

Morris, Eric A; Kirk, Donald W; Jia, Charles Q; Morita, Kazuki

2012-07-17

This work addresses the discrepancy in the literature regarding the effects of sulfuric acid (H(2)SO(4)) on elemental Hg uptake by activated carbon (AC). H(2)SO(4) in AC substantially increased Hg uptake by absorption particularly in the presence of oxygen. Hg uptake increased with acid amount and temperature exceeding 500 mg-Hg/g-AC after 3 days at 200 °C with AC treated with 20% H(2)SO(4). In the absence of other strong oxidizers, oxygen was able to oxidize Hg. Upon oxidation, Hg was more readily soluble in the acid, greatly enhancing its uptake by acid-treated AC. Without O(2), S(VI) in H(2)SO(4) was able to oxidize Hg, thus making it soluble in H(2)SO(4). Consequently, the presence of a bulk H(2)SO(4) phase within AC pores resulted in an orders of magnitude increase in Hg uptake capacity. However, the bulk H(2)SO(4) phase lowered the AC pore volume and could block the access to the active surface sites and potentially hinder Hg uptake kinetics. AC treated with SO(2) at 700 °C exhibited a much faster rate of Hg uptake attributed to sulfur functional groups enhancing adsorption kinetics. SO(2)-treated carbon maintained its fast uptake kinetics even after impregnation by 20% H(2)SO(4).

Calcium transport across the inner mitochondrial membrane: molecular mechanisms and pharmacology

PubMed Central

Csordás, György; Várnai, Peter; Golenár, Tünde; Sheu, Shey-Shing; Hajnóczky, György

2011-01-01

Growing evidence supports that mitochondrial calcium uptake is important for cell metabolism, signaling and survival. However, both the molecular nature of the mitochondrial Ca2+ transport sites and the calcium signals they respond to remained elusive. Recent RNA interference studies have identified new candidate proteins for Ca2+ uptake across the inner mitochondrial membrane, including LETM1, MCU, MICU1 and NCLX. The sensitivity of these factors to several drugs has been tested and in parallel, some new inhibitors of mitochondrial Ca2+ uptake have been described. This paper provides an update on the pharmacological aspects of the molecular mechanisms of the inner mitochondrial membrane Ca2+ transport. PMID:22123069

Calcium uptake in the skin of a freshwater teleost.

PubMed Central

McCormick, S D; Hasegawa, S; Hirano, T

1992-01-01

The skin, particularly the opercular membrane of some teleosts, contains mitochondrion-rich "chloride" cells and has been widely used as a model to study branchial salt-extrusion mechanisms in seawater fish. Skin isolated from the operculum of the freshwater Nile tilapia (Oreochromis niloticus) can transport Ca2+ against an ionic and electrical gradient. Adaptation of Nile tilapia to a low-Ca2+ environment increased the capacity of the opercular membrane to transport Ca2+. The density of mitochondrion-rich cells increased in parallel with Ca2+ transport capacity. The results demonstrate net Ca2+ uptake by vertebrate skin and strongly implicate mitochondrion-rich cells as the site of Ca2+ uptake in fresh water. Images PMID:1565659

The binding of calcium ions by erythrocytes and `ghost'-cell membranes

PubMed Central

Long, C.; Mouat, Barbara

1971-01-01

1. Washed human erythrocytes, suspended in iso-osmotic sucrose containing 2.5mm-calcium chloride, bind about 400μg-atoms of calcium/litre of packed cells. Sucrose may be replaced by other sugars. 2. Partial replacement of sucrose by iso-osmotic potassium chloride diminishes the uptake of calcium, 50% inhibition occurring at about 50mm-potassium chloride. 3. Other univalent cations behave like potassium, whereas bivalent cations are much more inhibitory. The tervalent cations, yttrium and lanthanum, however, are the most effective inhibitors of calcium uptake. 4. An approximate correlation exists between the calcium uptake and the sialic acid content of erythrocytes of various species and of human erythrocytes that have been partially depleted of sialic acid by treatment with neuraminidase. However, even after complete removal of sialic acid, human erythrocytes still bind about 140μg-atoms of calcium/litre of packed cells. 5. A Scatchard (1949) plot of calcium uptake at various Ca2+ concentrations in the suspending media shows the presence of three different binding sites on the external surface of the human erythrocyte membrane. 6. Erythrocyte `ghost' cells, the membranes of which appear to be permeable to Ca2+ ions, can bind about 1000μg-atoms of calcium per `ghost'-cell equivalent of 1 litre of packed erythrocytes. This indicates that there are also binding sites for calcium on the internal surface of the erythrocyte membrane. PMID:5124387

A hierarchical examination of methane uptake: field patterns, lab physiology, community composition and biogeography

NASA Astrophysics Data System (ADS)

von Fischer, J. C.; Koyama, A.; Johnson, N. G.; Webb, C. T.

2015-12-01

Scaling problems abound in biogeochemistry. At the finest scale, soil microbes experience habitats and environmental changes that affect the chemical transformations of interest. We collect the DNA of these organisms from sites across landscapes and note differences in who is there, and we seek to evaluate why group membership changes in space (biogeography) and why activity rates change over time (physiology). The goal of efforts at finer scales is often to better predict patterns at larger scales. We conducted such a hierarchical examination of methane uptake in the Great Plains grasslands of North America, gathering data from 22 plots at 8 field locations, scattered from South Dakota to New Mexico and Colorado to Kansas. Our work provides insight into methanotroph biogeochemistry at all of these scales. For example, we found that methane uptake rates vary mostly due to the methanotroph activity, and less so due to diffusivity. A combination of field and lab observations reveal that methanotroph communities differ in their sensitivity to soil moisture and to ammonium (an inhibitor of methanotrophy). Examination of methanotroph community composition reveals tantalizing patterns in composition, dominance and richness across sites, that appears to be structured by patterns of precipitation and soil texture. We anticipate that greater synthesis of these hierarchical findings will paint a richer picture of methanotroph life and enable improved prediction of methane uptake at regional scales.

18F-FDG uptake in the colon is modulated by metformin but not associated with core body temperature and energy expenditure.

PubMed

Bahler, Lonneke; Holleman, Frits; Chan, Man-Wai; Booij, Jan; Hoekstra, Joost B; Verberne, Hein J

2017-01-01

Physiological colonic 18F-fluorodeoxyglucose (18F-FDG) uptake is a frequent finding on 18F-FDG positron emission tomography computed tomography (PET-CT). Interestingly, metformin, a glucose lowering drug associated with moderate weight loss, is also associated with an increased colonic 18F-FDG uptake. Consequently, increased colonic glucose use might partly explain the weight losing effect of metformin when this results in an increased energy expenditure and/or core body temperature. Therefore, we aimed to determine whether metformin modifies the metabolic activity of the colon by increasing glucose uptake. In this open label, non-randomized, prospective mechanistic study, we included eight lean and eight overweight males. We measured colonic 18F-FDG uptake on PET-CT, energy expenditure and core body temperature before and after the use of metformin. The maximal colonic 18F-FDG uptake was measured in 5 separate segments (caecum, colon ascendens,-transversum,-descendens and sigmoid). The maximal colonic 18F-FDG uptake increased significantly in all separate segments after the use of metformin. There was no significant difference in energy expenditure or core body temperature after the use of metformin. There was no correlation between maximal colonic 18F-FDG uptake and energy expenditure or core body temperature. Metformin significantly increases colonic 18F-FDG uptake, but this increased uptake is not associated with an increase in energy expenditure or core body temperature. Although the colon might be an important site of the glucose plasma lowering actions of metformin, this mechanism of action does not explain directly any associated weight loss.

Comparison of L-serine uptake by human placental microvillous membrane vesicles and placental villous fragments.

PubMed

Brand, A P; Greenwood, S L; Glazier, J D; Bennett, E J; Godfrey, K M; Sibley, C P; Hanson, M A; Lewis, R M

2010-05-01

Both syncytiotrophoblast microvillous plasma membrane vesicles (MVM) and placental villous fragments are used to characterize the placental uptake of maternal substrate and to investigate changes in uptake associated with pathological conditions. However, the two techniques have not been directly compared. In this study uptake of (14)C-L-serine was compared in placental villous fragments and in MVM prepared from the same placentas. (14)C-L-serine uptake into MVM vesicles was mediated by System L and System A and smaller unidentified Na(+)-dependent and Na(+)-independent components. In villous fragments an unidentified Na(+)-dependent component mediated the majority of (14)C-L-serine uptake followed by System A and System L. The unidentified Na(+)-independent component of L-serine uptake was not detected in villous fragments. The ratio of System A activity to System L activity was similar in villous fragments and MVM vesicles. However, the unidentified Na(+)-dependent component in villous fragments was significantly higher than that in MVM vesicles. This indicates that the main differences in serine uptake mechanisms identified using the two techniques were not due to differences in System A and System L activity but to differences in the unidentified Na(+)-dependent component. This study suggests that uptake of L-serine into MVM vesicles and villous fragments via Systems A and L is comparable, but that this is not true for all components of L-serine uptake. (c) 2010 Elsevier Ltd. All rights reserved.

The interrelation between aPKC and glucose uptake in the skeletal muscle during contraction and insulin stimulation.

PubMed

Santos, J M; Benite-Ribeiro, S A; Queiroz, G; Duarte, J A

2014-12-01

Contraction and insulin increase glucose uptake in skeletal muscle. While the insulin pathway, better characterized, requires activation of phosphoinositide 3-kinase (PI3K) and atypical protein kinase (aPKC), muscle contraction seems to share insulin-activated components to increase glucose uptake. This study aimed to investigate the interrelation between the pathway involved in glucose uptake evoked by insulin and muscle contraction. Isolated muscle of rats was treated with solvent (control), insulin, wortmannin (PI3K inhibitor) and the combination of insulin plus wortmannin. After treatment, muscles were electrically stimulated (contracted) or remained at rest. Glucose transporter 4 (GLUT4) localization, glucose uptake and phospho-aPKC (aPKC activated form) were assessed. Muscle contraction and insulin increased glucose uptake in all conditions when compared with controls not stimulating an effect that was accompanied by an increase in GLUT4 and of phospho-aPKC at the muscle membrane. Contracted muscles treated with insulin did not show additive effects on glucose uptake or aPKC activity compared with the response when these stimuli were applied alone. Inhibition of PI3K blocked insulin effect on glucose uptake and aPKC but not in the contractile response. Thus, muscle contraction seems to stimulate aPKC and glucose uptake independently of PI3K. Therefore, aPKC may be a convergence point and a rate limit step in the pathway by which, insulin and contraction, increase glucose uptake in skeletal muscle. Copyright © 2014 John Wiley & Sons, Ltd.

Effect of enhanced manganese oxidation in the hyporheic zone on basin-scale geochemical mass balance

USGS Publications Warehouse

Harvey, Judson W.; Fuller, Christopher C.

1998-01-01

We determined the role of the hyporheic zone (the subsurface zone where stream water and shallow groundwater mix) in enhancing microbially mediated oxidation of dissolved manganese (to form manganese precipitates) in a drainage basin contaminated by copper mining. The fate of manganese is of overall importance to water quality in Pinal Creek Basin, Arizona, because manganese reactions affect the transport of trace metals. The basin-scale role of the hyporheic zone is difficult to quantify because stream-tracer studies do not always reliably characterize the cumulative effects of the hyporheic zone. This study determined cumulative effects of hyporheic reactions in Pinal Creek basin by characterizing manganese uptake at several spatial scales (stream-reach scale, hyporheic-flow-path scale, and sediment-grain scale). At the stream-reach scale a one-dimensional stream-transport model (including storage zones to represent hyporheic flow paths) was used to determine a reach-averaged time constant for manganese uptake in hyporheic zones, 1/λs, of 1.3 hours, which was somewhat faster but still similar to manganese uptake time constants that were measured directly in centimeter-scale hyporheic flow paths (1/λh= 2.6 hours), and in laboratory batch experiments using streambed sediment (1/λ = 2.7 hours). The modeled depths of subsurface storage zones (ds = 4–17 cm) and modeled residence times of water in storage zones (ts = 3–12 min) were both consistent with direct measurements in hyporheic flow paths (dh = 0–15 cm, th = 1–25 min). There was also good agreement between reach-scale modeling and direct measurements of the percentage removal of dissolved manganese in hyporheic flow paths (fs = 8.9%, andfh = 9.3%rpar;. Manganese uptake experiments in the laboratory using sediment from Pinal Creek demonstrated (through comparison of poisoned and unpoisoned treatments) that the manganese removal process was enhanced by microbially mediated oxidation. The cumulative effect of hyporheic exchange in Pinal Creek basin was to remove approximately 20% of the dissolved manganese flowing out of the drainage basin. Our results illustrate that the cumulative significance of reactive uptake in the hyporheic zone depends on the balance between chemical reaction rates, hyporheic porewater residence time, and turnover of streamflow through hyporheic flow paths. The similarity between the hyporheic reaction timescale (1/λs ≈ 1.3 hours), and the hyporheic porewater residence timescale (ts ≈ 8 min) ensured that there was adequate time for the reaction to progress. Furthermore, it was the similarity between the turnover length for stream water flow through hyporheic flow paths (Ls = stream velocity/storage-zone exchange coefficient ≈ 1.3 km) and the length of Pinal Creek (L ≈ 7 km), which ensured that all stream water passed through hyporheic flow paths several times. As a means to generalize our findings to other sites where similar types of hydrologic and chemical information are available, we suggest a cumulative significance index for hyporheic reactions, Rs = λstsL/Ls (dimensionless); higher values indicate a greater potential for hyporheic reactions to influence geochemical mass balance. Our experience in Pinal Creek basin suggests that values of Rs > 0.2 characterize systems where hyporheic reactions are likely to influence geochemical mass balance at the drainage-basin scale.

Subunit III-depleted cytochrome c oxidase provides insight into the process of proton uptake by proteins

PubMed Central

Varanasi, Lakshman; Hosler, Jonathan P.

2011-01-01

We review studies of subunit III-depleted cytochrome c oxidase (CcO III (−)) that elucidate the structural basis of steady-state proton uptake from solvent into an internal proton transfer pathway. The removal of subunit III from R. sphaeroides CcO makes proton uptake into the D pathway a rate-determining step, such that measurements of the pH dependence of steady-state O2 consumption can be used to compare the rate and functional pKa of proton uptake by D pathways containing different initial proton acceptors. The removal of subunit III also promotes spontaneous suicide inactivation by CcO, greatly shortening its catalytic lifespan. Because the probability of suicide inactivation is controlled by the rate at which the D pathway delivers protons to the active site, measurements of catalytic lifespan provide a second method to compare the relative efficacy of proton uptake by engineered CcO III (−) forms. These simple experimental systems have been used to explore general questions of proton uptake by proteins, such as the functional value of an initial proton acceptor, whether an initial acceptor must be surface-exposed, which side chains will function as initial proton acceptors and whether multiple acceptors can speed proton uptake. PMID:22023935

Estimating the contribution of bryophytes to the atmospheric COS budget

NASA Astrophysics Data System (ADS)

Gimeno, Teresa; Ogee, Jerome; Wingate, Lisa

2017-04-01

In the past decade, global biogeochemical modellers have embraced enthusiastically the potential of carbonyl sulphide (COS) as a tracer for gross primary productivity (GPP). COS is the most abundant sulphur-containing gas in the atmosphere, it is produced mainly in the ocean and it is consumed by the biosphere, with terrestrial vegetation being the most important contributor. Plant COS uptake is proportional to photosynthetic CO2 withdraw and that is why measurements of the biosphere-atmosphere COS flux can serve a proxy for GPP. Plant COS uptake is mediated by the light-independent enzyme carbonic anhydrase that irreversibly hydrolyses COS into H2S, which is quickly utilised as a sulphur source. Currently, there are no described plant-processes with COS as a by-product and hence the atmospheric-plant COS flux is assumed unidirectional. So far, we had focused on characterizing plant COS uptake dynamics on vascular plants and previous studies are consistent with the unidirectional flux assumption. However, although early works on sulphur metabolism suggested non-vascular plants might not abide to this assumption, we lack estimates of COS uptake dynamics for non-vascular communities. Bryophytes are key constituents of biocrusts and non-vascular photoautrophic communities and in temperate and cold latitudes contribute significantly to ecosystem carbon and nutrient cycling. We expect that in these ecosystems the coupling between COS and CO2 uptake will be influenced by specific environmental cues that control gas-exchange in bryophytes. We expect tissue hydration to be the most influential driver on COS uptake. In contrast, light would constrain CO2 but not COS uptake and therefore we expect greater uncoupling of COS and CO2 in the dark than in vascular plants. We characterized COS and CO2 uptake dynamics in two broadly distributed bryophytes, with contrasting life forms and evolutionary origins: the liverwort Marchantia polymorpha and the feather moss Scleropodium purum. We measured CO2 and COS uptake with varying hydration status, light and temperatures. Our results showed that COS uptake is limited by either excess or low tissue water content, similar to photosynthetic CO2 uptake. We found that COS uptake continued in the dark, despite impaired photosynthesis. We demonstrate that the COS flux in bryophytes is not unidirectional and that COS emissions are temperature and not light driven. Our results also suggest that both the uptake and the emission components are subject to seasonal regulation, with both uptakes limited in winter by low temperatures. Our results serve as a first approximation to model seasonal COS fluxes from air temperature and humidity in bryophyte-dominated ecosystems in high latitudes. We suggest that bryophytes might have an unexpected contribution to the ecosystem COS budget: during the day, when photosynthesis dominates the CO2 flux, COS emission are enhanced by warmer temperatures, while COS uptake is limited by tissue hydration and bryophytes act a net COS source; at night when the temperatures are cool and humidity is high, COS uptake dominates and bryophytes would act a net COS sink, while continuing to emit CO2 from respiration.

Molecular Speciation of Trace Metal Organic Complexes in the Pacific Ocean

NASA Astrophysics Data System (ADS)

Repeta, D.; Boiteau, R. M.; Bundy, R. M.; Babcock-Adams, L.

2017-12-01

Microbial production across approximately one third of the surface ocean is limited by extraordinarily low (picomolar) concentrations of dissolved iron, essentially all of which is complexed to strong organic ligands of unknown composition. Other biologically important trace metals (cobalt, copper, zinc, nickel) are also complexed to strong organic ligands, which again have not been extensively characterized. Nevertheless, organic ligands exert a strong influence on metal bioavailability and toxicity. For example, amendment experiments using commercially available siderophores, organic compounds synthesized by microbes to facilitate iron uptake, show these ligands can both facilitate or impede iron uptake depending on the siderophore composition and available uptake pathways. Over the past few years we have developed analytical techniques using high pressure liquid chromatography interfaced with inductively coupled plasma and electrospray ionization mass spectrometry to identify and quantify trace metal organic complexes in laboratory cultures of marine microbes and in seawater. We found siderophores to be widely distributed in the ocean, particularly in regions characterized by low iron concentrations. We also find chemically distinct complexes of copper, zinc, colbalt and nickel that we have yet to fully characterize. We will discuss some of our recent work on trace metal organic speciation in seawater and laboratory cultures, and outline future efforts to better understand the microbial cycling of trace metal organic complexes in the sea.

Review of Extraskeletal Activity on Tc-99m Methylene Diphosphonate Bone Scintigraphy and Value of Cross-Sectional and SPECT-CT Imaging Correlation.

PubMed

Bermo, Mohammed; Behnia, Sanaz; Fair, Joanna; Miyaoka, Robert S; Elojeimy, Saeed

2017-07-31

Recognizing the different mechanisms and imaging appearance of extraskeletal Tc-99m methylene diphosphonate uptake enhances the diagnostic value of bone scan interpretation. In this article, we present a pictorial review of the different mechanisms of extraskeletal Tc-99m methylene diphosphonate uptake on bone scintigraphy including neoplastic, inflammatory, ischemic, traumatic, excretory, and iatrogenic. We also illustrate through case examples the added value of correlation with cross-sectional and single photon emission computed tomography and computed tomography imaging in localizing and characterizing challenging cases of extraskeletal uptake. Copyright © 2017 Elsevier Inc. All rights reserved.

Characterization of Adsorption Enthalpy of Novel Water-Stable Zeolites and Metal-Organic Frameworks

NASA Astrophysics Data System (ADS)

Kim, Hyunho; Cho, H. Jeremy; Narayanan, Shankar; Yang, Sungwoo; Furukawa, Hiroyasu; Schiffres, Scott; Li, Xiansen; Zhang, Yue-Biao; Jiang, Juncong; Yaghi, Omar M.; Wang, Evelyn N.

2016-01-01

Water adsorption is becoming increasingly important for many applications including thermal energy storage, desalination, and water harvesting. To develop such applications, it is essential to understand both adsorbent-adsorbate and adsorbate-adsorbate interactions, and also the energy required for adsorption/desorption processes of porous material-adsorbate systems, such as zeolites and metal-organic frameworks (MOFs). In this study, we present a technique to characterize the enthalpy of adsorption/desorption of zeolites and MOF-801 with water as an adsorbate by conducting desorption experiments with conventional differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). With this method, the enthalpies of adsorption of previously uncharacterized adsorbents were estimated as a function of both uptake and temperature. Our characterizations indicate that the adsorption enthalpies of type I zeolites can increase to greater than twice the latent heat whereas adsorption enthalpies of MOF-801 are nearly constant for a wide range of vapor uptakes.

Characterization of Adsorption Enthalpy of Novel Water-Stable Zeolites and Metal-Organic Frameworks

PubMed Central

Kim, Hyunho; Cho, H. Jeremy; Narayanan, Shankar; Yang, Sungwoo; Furukawa, Hiroyasu; Schiffres, Scott; Li, Xiansen; Zhang, Yue-Biao; Jiang, Juncong; Yaghi, Omar M.; Wang, Evelyn N.

2016-01-01

Water adsorption is becoming increasingly important for many applications including thermal energy storage, desalination, and water harvesting. To develop such applications, it is essential to understand both adsorbent-adsorbate and adsorbate-adsorbate interactions, and also the energy required for adsorption/desorption processes of porous material-adsorbate systems, such as zeolites and metal-organic frameworks (MOFs). In this study, we present a technique to characterize the enthalpy of adsorption/desorption of zeolites and MOF-801 with water as an adsorbate by conducting desorption experiments with conventional differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). With this method, the enthalpies of adsorption of previously uncharacterized adsorbents were estimated as a function of both uptake and temperature. Our characterizations indicate that the adsorption enthalpies of type I zeolites can increase to greater than twice the latent heat whereas adsorption enthalpies of MOF-801 are nearly constant for a wide range of vapor uptakes. PMID:26796523

A factor influence study of trace element bioaccumulation in moss bags.

PubMed

Cesa, M; Campisi, B; Bizzotto, A; Ferraro, C; Fumagalli, F; Nimis, P L

2008-10-01

Moss bags of Rhynchostegium riparioides were exposed to different water concentrations of 11 trace elements under laboratory conditions, according to a saturated fractional factorial design (67 treated combinations), with the aim of measuring (1) element uptake and (2) the main effects and first-order interactions of influent factors. Bioaccumulation was directly proportional to water concentration, but the uptake ratio (ranging from 10(2) to 10(5)) also depended on the concentration of other metals. The highest uptake ratios were observed for Al, Cu, Cr, Hg, and Pb. The multiple regression model showed that interactions among elements exist and induce both antagonism (Fe is the most frequent competitor) and synergism (Cr exerts a great influence on Pb and Zn uptake). Interactions might be relatively strong (as for As, Cr, and Pb) or weak (Cd and Hg). This evidence should be taken into consideration in biomonitoring surveys of industrial sites, where effluents release more than one contaminant.

Conformational coupling between the active site and residues within the K(C)-channel of the Vibrio cholerae cbb3-type (C-family) oxygen reductase.

PubMed

Ahn, Young O; Mahinthichaichan, Paween; Lee, Hyun Ju; Ouyang, Hanlin; Kaluka, Daniel; Yeh, Syun-Ru; Arjona, Davinia; Rousseau, Denis L; Tajkhorshid, Emad; Adelroth, Pia; Gennis, Robert B

2014-10-21

The respiratory chains of nearly all aerobic organisms are terminated by proton-pumping heme-copper oxygen reductases (HCOs). Previous studies have established that C-family HCOs contain a single channel for uptake from the bacterial cytoplasm of all chemical and pumped protons, and that the entrance of the K(C)-channel is a conserved glutamate in subunit III. However, the majority of the K(C)-channel is within subunit I, and the pathway from this conserved glutamate to subunit I is not evident. In the present study, molecular dynamics simulations were used to characterize a chain of water molecules leading from the cytoplasmic solution, passing the conserved glutamate in subunit III and extending into subunit I. Formation of the water chain, which controls the delivery of protons to the K(C)-channel, was found to depend on the conformation of Y241(Vc), located in subunit I at the interface with subunit III. Mutations of Y241(Vc) (to A/F/H/S) in the Vibrio cholerae cbb3 eliminate catalytic activity, but also cause perturbations that propagate over a 28-Å distance to the active site heme b3. The data suggest a linkage between residues lining the K(C)-channel and the active site of the enzyme, possibly mediated by transmembrane helix α7, which contains both Y241(Vc) and the active site cross-linked Y255(Vc), as well as two CuB histidine ligands. Other mutations of residues within or near helix α7 also perturb the active site, indicating that this helix is involved in modulation of the active site of the enzyme.

Site of water vapor absorption in the desert cockroach, Arenivaga investigata.

PubMed Central

O'Donnell, M J

1977-01-01

The desert cockroach, Arenivaga investigata, can gain weight by absorption of water-vapor from unsaturated atmospheres above 82.5% relative humidity. Blocking the anus or the dorsal surface with wax does not prevent water vapor uptake, but interference with movements of the mouthparts or blocking the mouth with wax-prevents such uptake. Weight gains are associated with the protrusion from the mouth of two bladder-like extensions of the hypopharynx. During absorption these structures are warmer than the surrounding mouthparts, their surface temperature increasing with relative humidity. This suggests that the surfaces of the bladder-like structures function at least as sites for condensation of water vapor, but the precise location of its transfer into the hemolymph has not yet been identified. Images PMID:266217

Characterization of ursodeoxycholic and norursodeoxycholic acid as substrates of the hepatic uptake transporters OATP1B1, OATP1B3, OATP2B1 and NTCP.

PubMed

König, Jörg; Klatt, Sabine; Dilger, Karin; Fromm, Martin F

2012-08-01

Ursodeoxycholic acid (UDCA) is the only approved treatment for primary biliary cirrhosis, and norursodeoxycholic acid (norUDCA) is currently tested in clinical trials for future treatment of primary sclerosing cholangitis because of beneficial effects in cholestatic Mdr2 knock-out mice. Uptake of UDCA and norUDCA into hepatocytes is believed to be a prerequisite for subsequent metabolism and therapeutic action. However, the molecular determinants of hepatocellular uptake of UDCA and norUDCA are poorly understood. We therefore investigated whether UDCA and norUDCA are substrates of the hepatic uptake transporters OATP1B1, OATP1B3, OATP2B1 and Na(+) -taurocholate co-transporting polypeptide (NTCP), which are localized in the basolateral membrane of hepatocytes. Uptake of [(3) H]UDCA and [(14) C]norUDCA into Human embryonic kidney (HEK) cells stably expressing OATP1B1, OATP1B3, OATP2B1 or NTCP was investigated and compared with uptake into vector control cells. Uptake ratios were calculated by dividing uptake into transporter-transfected cells by uptake into respective control cells. Uptake ratios of OATP1B1-, OATP1B3- and OATP2B1-mediated UDCA and norUDCA uptake were at maximum 1.23 and 1.49, respectively. Uptake of UDCA was significantly higher into HEK-NTCP cells only at the lowest tested concentration (1 μM, p < 0.001) compared with the control cells with an uptake ratio of 1.34-fold. NorUDCA was not significantly transported by NTCP. The low uptake rates suggest that OATP1B1, OATP1B3, OATP2B1 and NTCP are not relevant for hepatocellular uptake and effects of UDCA and norUDCA in human beings. © 2012 The Authors Basic & Clinical Pharmacology & Toxicology © 2012 Nordic Pharmacological Society.

Determinants of physiological uptake of 18F-fluorodeoxyglucose in palatine tonsils.

PubMed

Birkin, Emily; Moore, Katherine S; Huang, Chao; Christopher, Marshall; Rees, John I; Jayaprakasam, Vetrisudar; Fielding, Patrick A

2018-06-01

To determine the extent of physiological variation of uptake of F-flurodeoxyglucose (FDG) within palatine tonsils. To define normal limits for side-to-side variation and characterize factors affecting tonsillar uptake of FDG.Over a period of 16 weeks 299 adult patients at low risk for head and neck pathology, attending our center for FDG positron emission tomography/computed tomography (PET/CT) scans were identified. The maximum standardized uptake value (SUVmax) was recorded for each palatine tonsil. For each patient age, gender, smoking status, scan indication and prior tonsillectomy status as well as weather conditions were noted.There was a wide variation in palatine tonsil FDG uptake with SUVmax values between 1.3 and 11.4 recorded. There was a strong left to right correlation for tonsillar FDG uptake within each patient (P < .01). The right palatine tonsil showed increased FDG uptake (4.63) compared to the left (4.47) (P < .01). In multivariate analysis, gender, scan indication, and prevailing weather had no significant impact of tonsillar FDG uptake. Lower tonsillar uptake was seen in patients with a prior history of tonsillectomy (4.13) than those without this history (4.64) (P < .01). Decreasing tonsillar FDG uptake was seen with advancing age (P < .01). Significantly lower uptake was seen in current smokers (SUVmax 4.2) than nonsmokers (SUV 4.9) (P = .03).Uptake of FDG in palatine tonsils is variable but shows a strong side-to-side correlation. We suggest the left/ right SUVmax ratio as a guide to normality with a first to 99th percentiles of (0.70-1.36) for use in patients not suspected to have tonsillar pathology.

Selected Phytochemicals and Culinary Plant Extracts Inhibit Fructose Uptake in Caco-2 Cells.

PubMed

Lee, Yurim; Lim, Yeni; Kwon, Oran

2015-09-18

This study compared the ability of nine culinary plant extracts containing a wide array of phytochemicals to inhibit fructose uptake and then explored the involvement of intestinal fructose transporters and phytochemicals for selected samples. The chemical signature was characterized by high performance liquid chromatography with mass spectrometry. Inhibition of [(14)C]-fructose uptake was tested by using human intestinal Caco-2 cells. Then, the relative contribution of the two apical-facing intestinal fructose transporters, GLUT2 and GLUT5, and the signature components for fructose uptake inhibition was confirmed in naive, phloretin-treated and forskolin-treated Caco-2 cells. HPLC/MS analysis of the chemical signature revealed that guava leaf contained quercetin and catechin, and turmeric contained curcumin, bisdemethoxycurcumin and dimethoxycurcumin. Similar inhibition of fructose uptake (by ~50%) was observed with guava leaf and turmeric in Caco-2 cells, but with a higher contribution of GLUT2 for turmeric and that of GLUT5 for guava leaf. The data suggested that, in turmeric, demethoxycurcumin specifically contributed to GLUT2-mediated fructose uptake inhibition, and curcumin did the same to GLUT5-mediated fructose uptake inhibition, but GLUT2 inhibition was more potent. By contrast, in guava leaf, catechin specifically contributed to GLUT5-mediated fructose uptake inhibition, and quercetin affected both GLUT5- and GLUT2-mediated fructose uptake inhibition, resulting in the higher contribution of GLUT5. These results suggest that demethoxycurcumin is an important contributor to GLUT2-mediated fructose uptake inhibition for turmeric extract, and catechin is the same to GLUT5-mediated fructose uptake inhibition for guava leaf extract. Quercetin, curcumin and bisdemethoxycurcumin contributed to both GLUT5- and GLUT2-mediated fructose uptake inhibition, but the contribution to GLUT5 inhibition was higher than the contribution to GLUT2 inhibition.

Overcoming phytoremediation limitations. A case study of Hg contaminated soil

NASA Astrophysics Data System (ADS)

Barbafieri, Meri

2013-04-01

Phytoremediation is a broad term that comprises several technologies to clean up water and soil. Despite the numerous articles appearing in scientific journals, very few field applications of phytoextraction have been successfully realized. The research here reported on Phytoextraction, the use the plant to "extract" metals from contaminated soil, is focused on implementations to overcome two main drawbacks: the survival of plants in unfavorable environmental conditions (contaminant toxicity, low fertility, etc.) and the often lengthy time it takes to reduce contaminants to the requested level. Moreover, to overcome the imbalance between the technology's potential and its drawbacks, there is growing interest in the use of plants to reduce only the fraction that is the most hazardous to the environment and human health, that is to target the bioavailable fractions of metals in soil. Bioavailable Contaminant Stripping (BCS) would be a remediation approach focused to remove the bioavailable metal fractions. BCS have been used in a mercury contaminated soil from Italian industrial site. Bioavailable fractions were determined by sequential extraction with H2O and NH4Cl.Combined treatments of plant hormone and thioligand to strength Hg uptake by crop plants (Brassica juncea and Helianthus annuus) were tested. Plant biomass, evapotranspiration, Hg uptake and distribution following treatments were compared. Results indicate the plant hormone, cytokinine (CK) foliar treatment, increased evapotranspiration rate in both tested plants. The Hg uptake and translocation in both tested plants increased with simultaneous addition of CK and TS treatments. B. juncea was the most effective in Hg uptake. Application of CK to plants grown in TS-treated soil lead to an increase in Hg concentration of 232% in shoots and 39% in roots with respect to control. While H. annuus gave a better response in plant biomass production, the application of CK to plants grown in TS-treated soil lead to an increase in Hg concentration of 248% in shoots and 185% in roots with respect to control plants. The BCS efficiency were evaluated analyzing the labile-Hg residue in the soil after the plant growing. Plants grown with CK and TS in one growing cycle significantly affected labile-Hg pools in soil characterized by sequential extraction, but did not significantly reduce the total metals in the soil. Moreover, if properly optimized, the use of a coupled phytohormone/thioligand system may be a viable strategy to strength Hg uptake by crop plants.

Magnetic iron oxide and manganese-doped iron oxide nanoparticles for the collection of alpha-emitting radionuclides from aqueous solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Hara, Matthew J.; Carter, Jennifer C.; Warner, Cynthia L.

Magnetic nanoparticles are well known to possess chemically active surfaces and large surface areas that can be employed to extract a range of ions from aqueous solutions. In addition, their superparamagnetic properties provide a convenient means for bulk collection of the material from solution after the targeted ions have been adsorbed. We evaluated two nanoscale amphoteric metal oxides, each possessing useful magnetic attributes for their ability to collect trace levels of a chemically diverse range of alpha emitting radioactive isotopes (polonium (Po), radium (Ra), uranium (U), and americium (Am)) from a wide range of aqueous solutions. The nanomaterials include commerciallymore » available magnetite (Fe3O4) and magnetite modified to incorporate manganese (Mn) into the crystal structure. The chemical stability of these nanomaterials was evaluated in Hanford Site, WA ground water between the natural pH (~8) and pH 1. Whereas the magnetite was observed to have good stability over the pH range, the Mn-doped material was observed to leach Mn at low pH. The materials were evaluated in parallel to characterize their uptake performance of the alpha-emitting radionuclide spikes from ground water across a range of pH (from ~8 down to 2). In addition, radiotracer uptake experiments were performed on Columbia River water, seawater, and human urine at their natural pH and at pH 2. Despite the observed leaching of Mn from the Mn-doped nanomaterial in the lower pH range, it exhibited generally superior analyte extraction performance compared to the magnetite, and analyte uptake was observed across a broader pH range. We show that the uptake behavior of the various radiotracers on these two materials at different pH levels can generally be explained by the amphoteric nature of the nanoparticle surfaces. Finally, the rate of sorption of the radiotracers on the two materials in unacidified ground water was evaluated. The uptake curves generally indicate that equilibrium is obtained within a few minutes, which is attributed to the high surface areas of the nanomaterials and the high level of dispersion in the liquids. In sum, our results indicate that these nanomaterials may have the potential to be employed for a range of applications to extract radionuclides from aqueous solutions.« less

Magnetic iron oxide and manganese-doped iron oxide nanoparticles for the collection of alpha-emitting radionuclides from aqueous solutions

DOE PAGES

O'Hara, Matthew J.; Carter, Jennifer C.; Warner, Cynthia L.; ...

2016-10-31

Magnetic nanoparticles are well known to possess chemically active surfaces and large surface areas that can be employed to extract a range of ions from aqueous solutions. In addition, their superparamagnetic properties provide a convenient means for bulk collection of the material from solution after the targeted ions have been adsorbed. We evaluated two nanoscale amphoteric metal oxides, each possessing useful magnetic attributes for their ability to collect trace levels of a chemically diverse range of alpha emitting radioactive isotopes (polonium (Po), radium (Ra), uranium (U), and americium (Am)) from a wide range of aqueous solutions. The nanomaterials include commerciallymore » available magnetite (Fe3O4) and magnetite modified to incorporate manganese (Mn) into the crystal structure. The chemical stability of these nanomaterials was evaluated in Hanford Site, WA ground water between the natural pH (~8) and pH 1. Whereas the magnetite was observed to have good stability over the pH range, the Mn-doped material was observed to leach Mn at low pH. The materials were evaluated in parallel to characterize their uptake performance of the alpha-emitting radionuclide spikes from ground water across a range of pH (from ~8 down to 2). In addition, radiotracer uptake experiments were performed on Columbia River water, seawater, and human urine at their natural pH and at pH 2. Despite the observed leaching of Mn from the Mn-doped nanomaterial in the lower pH range, it exhibited generally superior analyte extraction performance compared to the magnetite, and analyte uptake was observed across a broader pH range. We show that the uptake behavior of the various radiotracers on these two materials at different pH levels can generally be explained by the amphoteric nature of the nanoparticle surfaces. Finally, the rate of sorption of the radiotracers on the two materials in unacidified ground water was evaluated. The uptake curves generally indicate that equilibrium is obtained within a few minutes, which is attributed to the high surface areas of the nanomaterials and the high level of dispersion in the liquids. In sum, our results indicate that these nanomaterials may have the potential to be employed for a range of applications to extract radionuclides from aqueous solutions.« less

Mechanisms of Protein Seeding in Neurodegenerative Diseases

PubMed Central

Walker, Lary C.; Diamond, Marc I.; Duff, Karen E.; Hyman, Bradley T.

2013-01-01

Most age-associated neurodegenerative diseases involve the aggregation of specific proteins within the nervous system. In Alzheimer’s disease, the insidious pathogenic process begins many years before the symptoms emerge, and the lesions that characterize the disease – senile plaques and neurofibrillary tangles – ramify systematically through the brain. We review evidence that the β-amyloid and tau proteins, which aggregate to form senile plaques and neurofibrillary tangles, respectively, are induced to misfold and self-assemble by a process of templated conformational change that amplifies a toxic species. Recent data also indicate that the spread of these lesions from one site to another is mediated by the cellular uptake, transport and release of endogenous seeds formed by the cognate proteins. This simple pathogenic principle suggests that the formation, trafficking and metabolism of pathogenic protein seeds are promising therapeutic targets for Alzheimer’s disease and other neurodegenerative disorders. PMID:23599928

Selective extraction of clonazepam from human plasma and urine samples by molecularly imprinted polymeric beads.

PubMed

Panahi, Homayon Ahmad; Mehramizi, Ali; Ghassemi, Somayeh; Moniri, Elham

2014-03-01

A molecularly imprinted polymer (MIP) based on free-radical polymerization was prepared with 1-(N,N-biscarboxymethyl)amino-3-allylglycerol and N,N-dimethylacrylamide as functional monomers, N,N-methylene diacrylamide as the cross-linker, copper ion-clonazepam as the template and 2,2-azobis(2-methylbutyronitrile) as the initiator. The imprinted polymer was characterized by Fourier transform infrared spectroscopy, elemental analysis, thermo-gravimetric analysis, and SEM. The MIP of agglomerated microparticles with multipores was used for SPE. The imprinted polymer sorbent was selective for clonazepam. The optimum pH and sorption capacity were 5 and 0.18 mg/g at 20C, respectively. The profile of the drug uptake by the sorbent reflects good accessibility of the active sites in the imprinted polymer sorbent. The MIP-SPE was the most feasible technique for the extraction of clonazepam with a high recovery from human plasma and urine samples.

Uptake and intracellular processing of PEG-liposomes and PEG-immunoliposomes by kupffer cells in vitro 1 *.

PubMed

Koning, G A; Morselt, H W; Kamps, J A; Scherphof, G L

2001-01-01

Specific targeting of drugs to for instance tumors or sites of inflammation may be achieved by means of immunoliposomes carrying site-specific antibodies on their surface. The presence of these antibodies may adversely affect the circulation kinetics of such liposomes as a result of interactions with cells of the mononuclear phagocyte system (MPS), mainly represented by macrophages in liver and spleen. The additional insertion of poly(ethylene glycol) chains on the surface of the immunoliposomes may, however, attenuate this effect. We investigated the influence of surface-coupled rat or rabbit antibodies and of PEG on the uptake of liposomes by rat Kupffer cells in culture with (3)H-cholesteryloleyl ether as a metabolically stable marker. Additionally, we assessed the effects of surface-bound IgG and PEG on the intracellular processing of the liposomes by the Kupffer cells, based on a double-label assay using the (3)H-cholesteryl ether as an absolute measure for liposome uptake and the hydrolysis of the degradable marker cholesteryl-(14)C-oleate as relative measure of degradation. Attachment of both rat and rabbit antibodies to PEG-free liposomes caused a several-fold increase in apparent size. The uptake by Kupffer cells, however, was 3-4 fold higher for the rat than for the rabbit IgG liposomes. The presence of PEG drastically reduced the difference between these liposome types. Uptake of liposomes without antibodies amounted to only about 10% (non-PEGylated) or less (PEGylated) of that of the immunoliposomes. In contrast to the marked effects of IgG and PEG on Kupffer cell uptake, the rate of intracellular processing of the liposomes remained virtually unaffected by the presence of these substances on the liposomal surface. These observations are discussed with respect to the design of optimally formulated liposomal drug preparations, combining maximal therapeutic efficacy with minimal toxicity.

Transport of polyamines in Drosophila S2 cells: kinetics, pharmacology and dependence on the plasma membrane proton gradient

PubMed Central

Romero-Calderón, Rafael; Krantz, David E.

2005-01-01

Polyamine transport activities have been described in diverse multicellular systems, but their bioenergetic mechanisms and molecular identity remain unclear. In the present paper, we describe a high-affinity spermine/spermidine transport activity expressed in Drosophila S2 cells. Ion-replacement experiments indicate that polyamine uptake across the cell membrane is Na+-, K+-, Cl−- and Ca2+-independent, but pH-sensitive. Additional experiments using ionophores suggest that polyamine uptake may be H+-coupled. Pharmacological experiments show that polyamine uptake in S2 cells is selectively blocked by MGBG {methylglyoxal bis(guanylhydrazone) or 1,1′-[(methylethanediylidine)-dinitrilo]diguanidine} and paraquat (N,N-dimethyl-4,4′-bipyridylium), two known inhibitors of polyamine uptake in mammalian cells. In addition, inhibitors known to block the Slc22 (solute carrier 22) family of organic anion/cation transporters inhibit spermine uptake in S2 cells. These data and the genetic tools available in Drosophila will facilitate the molecular identification and further characterization of this activity. PMID:16248856

Transport of polyamines in Drosophila S2 cells: kinetics, pharmacology and dependence on the plasma membrane proton gradient.

PubMed

Romero-Calderón, Rafael; Krantz, David E

2006-01-15

Polyamine transport activities have been described in diverse multicellular systems, but their bioenergetic mechanisms and molecular identity remain unclear. In the present paper, we describe a high-affinity spermine/spermidine transport activity expressed in Drosophila S2 cells. Ion-replacement experiments indicate that polyamine uptake across the cell membrane is Na+-, K+-, Cl-- and Ca2+-independent, but pH-sensitive. Additional experiments using ionophores suggest that polyamine uptake may be H+-coupled. Pharmacological experiments show that polyamine uptake in S2 cells is selectively blocked by MGBG {methylglyoxal bis(guanylhydrazone) or 1,1'-[(methylethanediylidine)-dinitrilo]diguanidine} and paraquat (N,N-dimethyl-4,4'-bipyridylium), two known inhibitors of polyamine uptake in mammalian cells. In addition, inhibitors known to block the Slc22 (solute carrier 22) family of organic anion/cation transporters inhibit spermine uptake in S2 cells. These data and the genetic tools available in Drosophila will facilitate the molecular identification and further characterization of this activity.

Atmospheric scavenging of solid rocket exhaust effluents

NASA Technical Reports Server (NTRS)

Fenton, D. L.; Purcell, R. Y.

1978-01-01

Solid propellant rocket exhaust was directly utilized to ascertain raindrop scavenging rates for hydrogen chloride. Two chambers were used to conduct the experiments; a large, rigid walled, spherical chamber stored the exhaust constituents, while the smaller chamber housing all the experiments was charged as required with rocket exhaust HCl. Surface uptake experiments demonstrated an HCl concentration dependence for distilled water. Sea water and brackish water HCl uptake was below the detection limit of the chlorine-ion analysis technique used. Plant life HCl uptake experiments were limited to corn and soybeans. Plant age effectively correlated the HCl uptake data. Metallic corrosion was not significant for single 20 minute exposures to the exhaust HCl under varying relative humidity. Characterization of the aluminum oxide particles substantiated the similarity between the constituents of the small scale rocket and the full size vehicles.

Enhancement of Glucose Uptake by Meso-Dihydroguaiaretic Acid through GLUT4 Up-Regulation in 3T3-L1 Adipocytes.

PubMed

Lee, Anna; Choi, Kyeong-Mi; Jung, Won-Beom; Jeong, Heejin; Kim, Ga-Yeong; Lee, Ju Hyun; Lee, Mi Kyeong; Hong, Jin Tae; Roh, Yoon-Seok; Sung, Sang-Hyun; Yoo, Hwan-Soo

2017-08-28

Type 2 diabetes is characterized by insulin resistance, which leads to increased blood glucose levels. Adipocytes are involved in the development of insulin resistance, resulting from the dysfunction of the insulin signaling pathway. In this study, we investigated whether meso -dihydroguaiaretic acid (MDGA) may modulate glucose uptake in adipocytes, and examined its mechanism of action. MDGA enhanced adipogenesis through up-regulation of peroxisome proliferator-activated receptor γ and CCAAT/enhancer-binding protein α in 3T3-L1 adipocytes partially differentiated with sub-optimal concentrations of insulin. MDGA also increased glucose uptake by stimulating expression and translocation of glucose transporter 4 (GLUT4) in adipocytes. These results suggest that MDGA may increase GLUT4 expression and its translocation by promoting insulin sensitivity, leading to enhanced glucose uptake.

Dual targeted polymeric nanoparticles based on tumor endothelium and tumor cells for enhanced antitumor drug delivery.

PubMed

Gupta, Madhu; Chashoo, Gousia; Sharma, Parduman Raj; Saxena, Ajit Kumar; Gupta, Prem Narayan; Agrawal, Govind Prasad; Vyas, Suresh Prasad

2014-03-03

Some specific types of tumor cells and tumor endothelial cells represented CD13 proteins and act as receptors for Asn-Gly-Arg (NGR) motifs containing peptide. These CD13 receptors can be specifically recognized and bind through the specific sequence of cyclic NGR (cNGR) peptide and presented more affinity and specificity toward them. The cNGR peptide was conjugated to the poly(ethylene glycol) (PEG) terminal end in the poly(lactic-co-glycolic) acid PLGA-PEG block copolymer. Then, the ligand conjugated nanoparticles (cNGR-DNB-NPs) encapsulating docetaxel (DTX) were synthesized from preformed block copolymer by the emulsion/solvent evaporation method and characterized for different parameters. The various studies such as in vitro cytotoxicity, cell apoptosis, and cell cycle analysis presented the enhanced therapeutic potential of cNGR-DNB-NPs. The higher cellular uptake was also found in cNGR peptide anchored NPs into HUVEC and HT-1080 cells. However, free cNGR could inhibit receptor mediated intracellular uptake of NPs into both types of cells at 37 and 4 °C temperatures, revealing the involvement of receptor-mediated endocytosis. The in vivo biodistribution and antitumor efficacy studies indicated that targeted NPs have a higher therapeutic efficacy through targeting the tumor-specific site. Therefore, the study exhibited that cNGR-functionalized PEG-PLGA-NPs could be a promising approach for therapeutic applications to efficient antitumor drug delivery.

A novel heavy metal ATPase peptide from Prosopis juliflora is involved in metal uptake in yeast and tobacco.

PubMed

Keeran, Nisha S; Ganesan, G; Parida, Ajay K

2017-04-01

Heavy metal pollution of agricultural soils is one of the most severe ecological problems in the world. Prosopis juliflora, a phreatophytic tree species, grows well in heavy metal laden industrial sites and is known to accumulate heavy metals. Heavy Metal ATPases (HMAs) are ATP driven heavy metal pumps that translocate heavy metals across biological membranes thus helping the plant in heavy metal tolerance and phytoremediation. In the present study we have isolated and characterized a novel 28.9 kDa heavy metal ATPase peptide (PjHMT) from P. juliflora which shows high similarity to the C-terminal region of P 1B ATPase HMA1. It also shows the absence of the invariant signature sequence DKTGT, and the metal binding CPX motif but the presence of conserved regions like MVGEGINDAPAL (ATP binding consensus sequence), HEGGTLLVCLNS (metal binding domain) and MLTGD, GEGIND and HEGG motifs which play important roles in metal transport or ATP binding. PjHMT, was found to be upregulated under cadmium and zinc stress. Heterologous expression of PjHMT in yeast showed a higher accumulation and tolerance of heavy metals in yeast. Further, transgenic tobacco plants constitutively expressing PjHMT also showed increased accumulation and tolerance to cadmium. Thus, this study suggests that the transport peptide from P. juliflora may have an important role in Cd uptake and thus in phytoremediation.

Nitrogen fluxes in the forests of the Congo Basin

NASA Astrophysics Data System (ADS)

Bauters, Marijn; Verbeeck, Hans; Cizungu, Landry; Makelele, Isaac; Boeckx, Pascal

2017-04-01

The tropical forest of the Congo basin remains very poorly investigated and understood; mainly because of logistic, political and research capacity constraints. Nevertheless, characterization and monitoring of fundamental processes in this biome is vital to understand future responses and to correctly parameterize Earth system models. Nutrient fluxes are key in these processes for the functioning of tropical forests, since CO2 uptake by terrestrial ecosystems strongly depends on site fertility, i.e. nutrient availability. Accurate projections of future net forest growth and terrestrial CO2 uptake thus necessitate an improved understanding on nutrient cycles and how these are coupled to the carbon (C) cycle in forests. Research in the Congo Basin region should combine assessments of both carbon fluxes and the underlying nutrient cycles which directly impact the forest productivity. We set up a monitoring network for nitrogen fluxes in four different forest types in the Congo Basin, resulting in a unique and integrate dataset. The questions to be answered: How do the N-budgets of four different forest types in the Congo Basin compare? How do these fluxes compare to fluxes in the Amazon forest? What is the influence from the strong slash-and-burn regimes on the N-cycle in the natural forests? We answer these questions with our empirical dataset of one hydrological year, combined with satellite and modeling data.

Development of 4-hexadecyl-4,7-diaza-1,10-decanedithiol (HDD) kit for the preparation of the liver cancer therapeutic agent Re-188-HDD/lipiodol.

PubMed

Banka, Vinay Kumar; Moon, Sung-Hyun; Jeong, Jae Min; Seelam, Sudhakara Reddy; Lee, Yun-Sang; Kim, Young Joo; Lee, Dong Soo; Chung, June-Key

2015-03-01

A lipiodol solution of (188)Re-4-hexadecyl-2,2,9,9-tetramethyl-4,7-diaza-1,10-decanedithiol (HTDD) has been successfully developed for liver cancer therapy; however, its preparation requires a multi-step synthesis and it is characterized by a low labeling yield. We synthesized a new compound, 4-hexadecyl-4,7-diaza-1,10-decanedithioacetate (AHDD), without gem dimethyl groups to address these issues. AHDD was formulated into a kit and was labeled with (188)Re. Biodistribution study was performed using normal BALB/c mice. The kit was labeled with (188)Re with a high efficiency (98.8±0.2%). After extraction with lipiodol, the overall yield of (188)Re-HDD/lipiodol was as high as 90.2±2.6%. A comparative biodistribution study of (188)Re-HTDD and (188)Re-HDD was performed in normal mice after intravenous injection. The lungs were identified as the main uptake site due to capillary-blockage. (188)Re-HDD/lipiodol showed a significantly higher lung uptake than that of (188)Re-HTDD/lipiodol (p<0.05). The newly synthesized (188)Re-HDD/lipiodol showed improved radiolabeling yield and biodistribution results compared to (188)Re-HTDD/lipiodol, and may therefore be more suitable for liver cancer therapy. Copyright © 2014 Elsevier Inc. All rights reserved.

Precision spherical nucleic acids for delivery of anticancer drugs† †Electronic supplementary information (ESI) available: DNA nanoparticle design and assembly, evaluation of BKM120 encapsulation, structural characterization, stability and shelf-life of drug-loaded structures, cellular uptake in cancer cells, in vitro cell studies, HSA binding experiments and in vivo studies. See DOI: 10.1039/c7sc01619k Click here for additional data file. Click here for additional data file. Click here for additional data file.

PubMed Central

Bousmail, Danny; Amrein, Lilian; Fakhoury, Johans J.; Fakih, Hassan H.; Hsu, John C. C.

2017-01-01

We report a spherical nucleic acid (SNA) system for the delivery of BKM120, an anticancer drug for treatment of chronic lymphocytic leukemia (CLL). While promising for cancer treatment, this drug crosses the blood–brain barrier causing significant side-effects in patients. The DNA nanoparticle encapsulates BKM120 in high efficiency, and is unparalleled in its monodispersity, ease of synthesis and stability in different biological media and in serum. These DNA nanostructures demonstrate efficient uptake in human cervical cancer (HeLa) cells, and increased internalization of cargo. In vitro studies show that BKM120-loaded nanoparticles promote apoptosis in primary patient CLL lymphocytes, and act as sensitizers of other antitumor drugs, without causing non-specific inflammation. Evaluation of this drug delivery system in vivo shows long circulation times up to 24 hours, full body distribution, accumulation at tumor sites and minimal leakage through the blood–brain barrier. Our results demonstrate the great potential of these delivery vehicles as a general platform for chemotherapeutic drug delivery. PMID:28989655

Functional Analysis of Arabidopsis Sucrose Transporters

DOE Office of Scientific and Technical Information (OSTI.GOV)

John M. Ward

2009-03-31

Sucrose is the main photosynthetic product that is transported in the vasculature of plants. The long-distance transport of carbohydrates is required to support the growth and development of net-importing (sink) tissues such as fruit, seeds and roots. This project is focused on understanding the transport mechanism sucrose transporters (SUTs). These are proton-coupled sucrose uptake transporters (membrane proteins) that are required for transport of sucrose in the vasculature and uptake into sink tissues. The accomplishments of this project included: 1) the first analysis of substrate specificity for any SUT. This was accomplished using electrophysiology to analyze AtSUC2, a sucrose transporter frommore » companion cells in Arabidopsis. 2) the first analysis of the transport activity for a monocot SUT. The transport kinetics and substrate specificity of HvSUT1 from barley were studied. 3) the first analysis of a sucrose transporter from sugarcane. and 4) the first analysis of transport activity of a sugar alcohol transporter homolog from plants, AtPLT5. During this period four primary research papers, funded directly by the project, were published in refereed journals. The characterization of several sucrose transporters was essential for the current effort in the analysis of structure/function for this gene family. In particular, the demonstration of strong differences in substrate specificity between type I and II SUTs was important to identify targets for site-directed mutagenesis.« less

Linking CO 2 Sorption Performance to Polymer Morphology in Aminopolymer/Silica Composites through Neutron Scattering

DOE PAGES

Holewinski, Adam; Sakwa-Novak, Miles A.; Jones, Christopher W.

2015-08-26

Composites of poly(ethylenimine) (PEI) and mesoporous silica are effective, reversible adsorbents for CO 2, both from flue gas and in direct air-capture applications. The morphology of the PEI within the silica can strongly impact the overall carbon capture efficiency and rate of saturation. Here, we directly probe the spatial distribution of the supported polymer through small-angle neutron scattering (SANS). Combined with textural characterization from physisorption analysis, the data indicate that PEI first forms a thin conformal coating on the pore walls, but all additional polymer aggregates into plug(s) that grow along the pore axis. This model is consistent with observedmore » trends in amine-efficiency (CO 2/N binding ratio) and pore size distributions, and points to a trade-off between achieving high chemical accessibility of the amine binding sites, which are inaccessible when they strongly interact with the silica, and high accessibility for mass transport, which can be hampered by diffusion through PEI plugs. In conclusion, we illustrate this design principle by demonstrating higher CO 2 capacity and uptake rate for PEI supported in a hydrophobically modified silica, which exhibits repulsive interactions with the PEI, freeing up binding sites.« less

Simultaneous uptake of NOM and Microcystin-LR by anion exchange resins: Effect of inorganic ions and resin regeneration.

PubMed

Dixit, Fuhar; Barbeau, Benoit; Mohseni, Madjid

2018-02-01

This study investigated the efficiency of a strongly basic macroporous anion exchange resin for the co-removal of Microcystin-LR (MCLR) and natural organic matter (NOM) in waters affected by toxic algal blooms. Environmental factors influencing the uptake behavior included MCLR and resin concentrations, NOM and anionic species, specifically nitrate, sulphate and bicarbonate. A860 resin exhibited an excellent adsorption capacity of 3800 μg/g; more than 60% of the MCLR removal was achieved within 10 min with a resin dosage of 200 mg/L (∼1 mL/L). Further, kinetic studies revealed that the overall removal of MCLR is influenced by both external diffusion and intra-particle diffusion. Increasing NOM concentration resulted in a significant reduction of MCLR uptake, especially at lower resin dosages, where a competitive uptake between the charged NOM fractions and MCLR was observed due to limited active sites. In addition, MCLR uptake was significantly reduced in the presence of sulphate and nitrate in the water matrix. Moreover, performance of the resin proved to be stable from one regeneration cycle to another. Approximately 80% of MCLR and 50% of dissolved organic carbon (DOC) were recovered in the regenerated brine. Evidences of resin saturation and site reduction were also observed after 2000 bed volumes (BV) of operation. For all the investigated water matrices, a resin dosage of 1000 mg/L (∼4.5 mL/L) was sufficient to lower MCLR concentration from 100 μg/L to below the World Health Organization guideline of 1 μg/L, while simultaneously providing more than 80% NOM removal. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of Vegetation Cover on Rain Pulse Responses in Semi-Arid Savannas in Central Texas

NASA Astrophysics Data System (ADS)

Litvak, M.; Heilman, J.; McInnes, K.; Thijs, A.; Kjelgaard, J.

2007-12-01

Savannas in central Texas are dominated by live oak (Quercus virginiana) and Ashe juniper (Juniperus asheii) underlain by perennial, C3/C4 grasslands, and are increasingly becoming juniper and mesquite dominated due to overgrazing and suppression of wildfires. Since 2004, we have been investigating how carbon, water and energy exchange in these rain-limited savannas respond to rainfall variability and this observed vegetation change. In semi-arid regions, rainfall pulses provide inputs of soil moisture and trigger biotic activity in the form of plant gas exchange and microbial metabolism as well as water dependent physical processes in the soil. Each of these components has a different characteristic response curve to soil moisture and integrates soil water content over a different range of depths. Here we focus on examining how the observed increase of woody species in central Texas savannas alters the response of net ecosystem exchange and its components, ecosystem respiration and gross ecosystem exchange, to rain pulses. Using data we have collected over the last three years from three Ameriflux tower sites at Freeman Ranch near San Marcos, TX (C3/C4 grassland, juniper/mesquite savanna with 50 percent woody cover, and oak/juniper woodland), we quantify the responses of both ecosystem respiration and daily carbon uptake to rainfall pulses throughout the year. Specifically, we look at the enhancement and persistence of ecosystem respiration and carbon uptake responses following a pulse, and isolate the main controlling factors on the observed response: seasonality, antecedent soil moisture and temperature, or previous pulses. In all three land covers, the general response to precipitation pulses is a respiration pulse followed by an increase in total carbon uptake. Differences in pulse responses observed at the savanna site compared to the grassland and woodland sites can be explained, in part, by the observed differences in rooting structure and photosynthetic capacity due to differences in plant functional groups and leaf area index. The woodland site is most sensitive to winter pulses in terms of enhanced sink strength following pulses and is dependent on both temperature and pulse size. Both the grassland and shrubland sites show greater sink strength following summer pulses, rather than winter pulses. Both the ecosystem respiration and net uptake responses in all three sites are dependent upon whether there was shallow versus deep soil moisture recharge following pulses. Implications for the influence of future climate change on carbon dynamics in these savanna ecosystems will be discussed.

Characterization of Transporters in the Hepatic Uptake of TAK-475 M-I, a Squalene Synthase Inhibitor, in Rats and Humans.

PubMed

Ebihara, T; Takeuchi, T; Moriya, Y; Tagawa, Y; Kondo, T; Moriwaki, T; Asahi, S

2016-06-01

TAK-475 (lapaquistat acetate) is a squalene synthase inhibitor and M-I is a pharmacologically active metabolite of TAK-475. Preclinical pharmacokinetic studies have demonstrated that most of the dosed TAK-475 was hydrolyzed to M-I during the absorption process and the concentrations of M-I in the liver, the main organ of cholesterol biosynthesis, were much higher than those in the plasma after oral administration to rats. In the present study, the mechanism of the hepatic uptake of M-I was investigated.The uptake studies of (14)C-labeled M-I into rat and human hepatocytes indicated that the uptakes of M-I were concentrative, temperature-dependent and saturable in both species with Km values of 4.7 and 2.8 μmol/L, respectively. M-I uptake was also inhibited by cyclosporin A, an inhibitor for hepatic uptake transporters including organic anion transporting polypeptide (OATP). In the human hepatocytes, M-I uptake was hardly inhibited by estrone 3-sulfate as an inhibitor for OATP1B1, and most of the M-I uptake was Na(+)-independent. Uptake studies using human transporter-expressing cells revealed the saturable uptake of M-I for OATP1B3 with a Km of 2.13 μmol/L. No obvious uptake of M-I was observed in the OATP1B1-expressing cells.These results indicated that M-I was taken up into hepatocytes via transporters in both rats and humans. OATP1B3 would be mainly involved in the hepatic uptake of M-I in humans. These findings suggested that hepatic uptake transporters might contribute to the liver-selective inhibition of cholesterol synthesis by TAK-475. This is the first to clarify a carrier-mediated hepatic uptake mechanism for squalene synthase inhibitors. © Georg Thieme Verlag KG Stuttgart · New York.

Myths on Bi-direction Communication of Web 2.0 Based Social Networks: Is Social Network Truly Interactive?

DTIC Science & Technology

2011-03-10

more and more social interactions are happening on the on-line. Especially recent uptake of the social network sites (SNSs), such as Facebook (http...results give overviews on social interactions on a popular social network site . As each twitter account has different characteristics based on...the public and individuals post their private stories on their blogs and share their interests using social network sites . On the other hand, people

Surface chemistry of ferrihydrite: Part 2. Kinetics of arsenate adsorption and coprecipitation

USGS Publications Warehouse

Fuller, C.C.; Dadis, J.A.; Waychunas, G.A.

1993-01-01

The kinetics of As(V) adsorption by ferrihydrite was investigated in coprecipitation and postsynthesis adsorption experiments conducted in the pH range 7.5-9.0. In coprecipitation experiments, As(V) was present in solution during the hydrolysis and precipitation of iron. In adsorption experiments, a period of rapid (<5 min) As(V) uptake from solution was followed by continued uptake for at least eight days, as As(V) diffused to adsorption sites on ferrihydrite surfaces within aggregates of colloidal particles. The time dependence of As(V) adsorption is well described by a general model for diffusion into a sphere if a subset of surface sites located near the exterior of aggregates is assumed to attain adsorptive equilibrium rapidly. The kinetics of As(V) desorption after an increase in pH were also consistent with diffusion as a rate-limiting process. Aging of pure ferrihydrite prior to As(V) adsorption caused a decrease in adsorption sites on the precipitate owing to crystallite growth. In coprecipitation experiments, the initial As(V) uptake was significantly greater than in post-synthesis adsorption experiments, and the rate of uptake was not diffusion limited because As(V) was coordinated by surface sites before crystallite growth and coagulation processes could proceed. After the initial adsorption, As(V) was slowly released from coprecipitates for at least one month, as crystallite growth caused desorption of As(V). Adsorption densities as high as 0.7 mole As(V) per mole of Fe were measured in coprecipitates, in comparison to 0.25 mole As(V) per mole of Fe in post-synthesis adsorption experiments. Despite the high Concentration of As(V) in the precipitates, EXAFS spectroscopy (Waychunas et al., 1993) showed that neither ferric arsenate nor any other As-bearing surface precipitate or solid solution was formed. The high adsorption densities are possible because the ferrihydrite particles are extremely small, approaching the size of small dioctahedral chains at the highest As(V) adsorption density. The results suggest that the solid solution model proposed by Fox (1989, 1992) for control of arsenate and phosphate concentrations in natural waters may be invalid. ?? 1993.

Hot and Cool Spots of Primary Production, Respiration and 15N Nitrate and Ammonium Uptake: Spatial Heterogeneity in Tropical Streams and Rivers

NASA Astrophysics Data System (ADS)

Dodds, W. K.; Tromboni, F.; Neres-Lima, V.; Zandoná, E.; Moulton, T. P.

2016-12-01

While whole-stream measures of metabolism and uptake have become common methods to characterize biogeochemical transport and processing, less is known about how nitrogen (N) uptake, gross primary production (GPP) and ecosystem respiration (ER) covary among different stream substrata as smaller scales. We measured 15N ammonium and nitrate uptake seperately, and GPP and ER of ecosystem compartments (leaves, epilithon, sand-associated biota and macrophytes) in closed circulating chambers in three streams/ rivers of varied size. The streams drain pristine Brazilian Atlantic Rainforest watersheds and are all within a few km of eachother. The smallest stream had dense forest canopy cover; the largest river was almost completely open. GPP could not be detected in the closed canopy stream. Epilithon (biofilms on rocks) was a dominant compartment for GPP and N uptake in the two open streams, and macrophytes rivaled epilithon GPP and N uptake rates in the most open stream. Even though leaves covered only 1-3% of the stream bottom, they could account for around half of all the ER in the streams but almost no N uptake. Sand had minimal rates of N uptake, GPP and R associated with it in all streams due to relatively low organic material content. The data suggest that N uptake, GPP and ER of different substrata are not closely linked over relatively small spatial (dm) scales, and that different biogeochemical processes may map to different hot and cool spots for ecosystem rates.

Biodistribution of 99mTc-MAA on SPECT/CT performed for 90Y radioembolization therapy planning: a pictorial review.

PubMed

Bailey, J J; Dewaraja, Y; Hubers, D; Srinivasa, R N; Frey, K A

2017-10-01

To evaluate the frequency of 99mTc-MAA uptake in extrahepatic organs during 90Y radioembolization therapy planning. This retrospective case series of 70 subjects who underwent 99mTc-MAA hepatic artery perfusion studies between January 2014 and July 2016 for 90Y radioembolization therapy planning at our institution involved direct image review for all subjects, with endpoints recorded: lung shunt fraction, extrahepatic radiotracer uptake, time from MAA injection to imaging. Combined planar and SPECT/CT imaging findings in the 70 subjects demonstrated lung shunt fraction measurements of less than 10% in 53 (76%) subjects and greater than 10% in 17 (24%) subjects. All patients demonstrated renal cortical uptake, 23 (33%) demonstrated salivary gland uptake, 23 (33%) demonstrated thyroid uptake, and 32 (46%) demonstrated gastric mucosal uptake, with significant overlap between these groups. The range of elapsed times between MAA injection and initial imaging was 41-138 min, with a mean of 92 min. There was no correlation between time to imaging and the presence of extrahepatic radiotracer uptake at any site. During hepatic artery perfusion scanning for 90Y radioembolization therapy planning, extrahepatic uptake is common, particularly in the kidney, salivary gland, thyroid and gastric mucosa, and is hypothesized to result from breakdown of 99mTc-MAA over time. Given the breakdown to smaller aggregates and ultimately pertechnetate, this should not be a contraindication to actual Y-90 microsphere therapy. Although we found no correlation between time to imaging and extrahepatic uptake, most of our injection to imaging times were relatively short.

Crassulacean Acid Metabolism in the Epiphyte Tillandsia usneoides L. (Spanish Moss) 1

PubMed Central

Martin, Craig E.; Siedow, James N.

1981-01-01

Patterns of CO2 exchange in Spanish moss under various experimental conditions were measured using an infrared gas analysis system. Plants were collected from a study site in North Carolina and placed in a gas exchange chamber for several days of continuous measurements. No substantial seasonal effects on CO2 exchange were observed. High rates of nocturnal CO2 uptake were observed under day/night temperature regimes of 25/10, 25/15, 25/20, 30/20, and 35/20 C; however, daytime temperatures of 40 C eliminated nighttime CO2 uptake and a nighttime temperature of 5 C eliminated nocturnal CO2 uptake, regardless of day temperature. Constant chamber conditions also inhibited nocturnal CO2 uptake. Constant high relative humidity (RH) slightly stimulated CO2 uptake while low nighttime RH reduced nocturnal CO2 uptake. Reductions in daytime irradiance to approximately 25% full sunlight had no effect on CO2 exchange. Continuous darkness resulted in continuous CO2 loss by the plants, but a CO2 exchange pattern similar to normal day/night conditions was observed under constant illumination. High tissue water content inhibited CO2 uptake. Wetting of the tissue at any time of day or night resulted in net CO2 loss. Abrupt increases in temperature or decreases in RH resulted in sharp decreases in net CO2 uptake. The results indicate that Spanish moss is tolerant of a wide range of temperatures, irradiances, and water contents. They also indicate that high nighttime RH is a prerequisite for high rates of CO2 uptake. PMID:16661912

Crassulacean Acid Metabolism in the Epiphyte Tillandsia usneoides L. (Spanish Moss) : RESPONSES OF CO(2) EXCHANGE TO CONTROLLED ENVIRONMENTAL CONDITIONS.

PubMed

Martin, C E; Siedow, J N

1981-08-01

Patterns of CO(2) exchange in Spanish moss under various experimental conditions were measured using an infrared gas analysis system. Plants were collected from a study site in North Carolina and placed in a gas exchange chamber for several days of continuous measurements. No substantial seasonal effects on CO(2) exchange were observed. High rates of nocturnal CO(2) uptake were observed under day/night temperature regimes of 25/10, 25/15, 25/20, 30/20, and 35/20 C; however, daytime temperatures of 40 C eliminated nighttime CO(2) uptake and a nighttime temperature of 5 C eliminated nocturnal CO(2) uptake, regardless of day temperature. Constant chamber conditions also inhibited nocturnal CO(2) uptake. Constant high relative humidity (RH) slightly stimulated CO(2) uptake while low nighttime RH reduced nocturnal CO(2) uptake.Reductions in daytime irradiance to approximately 25% full sunlight had no effect on CO(2) exchange. Continuous darkness resulted in continuous CO(2) loss by the plants, but a CO(2) exchange pattern similar to normal day/night conditions was observed under constant illumination. High tissue water content inhibited CO(2) uptake. Wetting of the tissue at any time of day or night resulted in net CO(2) loss. Abrupt increases in temperature or decreases in RH resulted in sharp decreases in net CO(2) uptake.The results indicate that Spanish moss is tolerant of a wide range of temperatures, irradiances, and water contents. They also indicate that high nighttime RH is a prerequisite for high rates of CO(2) uptake.

Quantitating Antibody Uptake In Vivo: Conditional Dependence on Antigen Expression Levels

PubMed Central

Thurber, Greg M.; Weissleder, Ralph

2010-01-01

Purpose Antibodies form an important class of cancer therapeutics, and there is intense interest in using them for imaging applications in diagnosis and monitoring of cancer treatment. Despite the expanding body of knowledge describing pharmacokinetic and pharmacodynamic interactions of antibodies in vivo, discrepancies remain over the effect of antigen expression level on tumoral uptake with some reports indicating a relationship between uptake and expression and others showing no correlation. Procedures Using a cell line with high EpCAM expression and moderate EGFR expression, fluorescent antibodies with similar plasma clearance were imaged in vivo. A mathematical model and mouse xenograft experiments were used to describe the effect of antigen expression on uptake of these high affinity antibodies. Results As predicted by the theoretical model, under subsaturating conditions, uptake of the antibodies in such tumors is similar because localization of both probes is limited by delivery from the vasculature. In a separate experiment, when the tumor is saturated, the uptake becomes dependent on the number of available binding sites. In addition, targeting of small micrometastases is shown to be higher than larger vascularized tumors. Conclusions These results are consistent with the prediction that high affinity antibody uptake is dependent on antigen expression levels for saturating doses and delivery for subsaturating doses. It is imperative for any probe to understand whether quantitative uptake is a measure of biomarker expression or transport to the region of interest. The data provide support for a predictive theoretical model of antibody uptake, enabling it to be used as a starting point for the design of more efficacious therapies and timely quantitative imaging probes. PMID:20809210

Quantitating antibody uptake in vivo: conditional dependence on antigen expression levels.

PubMed

Thurber, Greg M; Weissleder, Ralph

2011-08-01

Antibodies form an important class of cancer therapeutics, and there is intense interest in using them for imaging applications in diagnosis and monitoring of cancer treatment. Despite the expanding body of knowledge describing pharmacokinetic and pharmacodynamic interactions of antibodies in vivo, discrepancies remain over the effect of antigen expression level on tumoral uptake with some reports indicating a relationship between uptake and expression and others showing no correlation. Using a cell line with high epithelial cell adhesion molecule expression and moderate epidermal growth factor receptor expression, fluorescent antibodies with similar plasma clearance were imaged in vivo. A mathematical model and mouse xenograft experiments were used to describe the effect of antigen expression on uptake of these high-affinity antibodies. As predicted by the theoretical model, under subsaturating conditions, uptake of the antibodies in such tumors is similar because localization of both probes is limited by delivery from the vasculature. In a separate experiment, when the tumor is saturated, the uptake becomes dependent on the number of available binding sites. In addition, targeting of small micrometastases is shown to be higher than larger vascularized tumors. These results are consistent with the prediction that high affinity antibody uptake is dependent on antigen expression levels for saturating doses and delivery for subsaturating doses. It is imperative for any probe to understand whether quantitative uptake is a measure of biomarker expression or transport to the region of interest. The data provide support for a predictive theoretical model of antibody uptake, enabling it to be used as a starting point for the design of more efficacious therapies and timely quantitative imaging probes.

18F-FDG uptake in the colon is modulated by metformin but not associated with core body temperature and energy expenditure

PubMed Central

Bahler, Lonneke; Holleman, Frits; Chan, Man-Wai; Booij, Jan; Hoekstra, Joost B.; Verberne, Hein J.

2017-01-01

Purpose Physiological colonic 18F-fluorodeoxyglucose (18F-FDG) uptake is a frequent finding on 18F-FDG positron emission tomography computed tomography (PET-CT). Interestingly, metformin, a glucose lowering drug associated with moderate weight loss, is also associated with an increased colonic 18F-FDG uptake. Consequently, increased colonic glucose use might partly explain the weight losing effect of metformin when this results in an increased energy expenditure and/or core body temperature. Therefore, we aimed to determine whether metformin modifies the metabolic activity of the colon by increasing glucose uptake. Methods In this open label, non-randomized, prospective mechanistic study, we included eight lean and eight overweight males. We measured colonic 18F-FDG uptake on PET-CT, energy expenditure and core body temperature before and after the use of metformin. The maximal colonic 18F-FDG uptake was measured in 5 separate segments (caecum, colon ascendens,—transversum,—descendens and sigmoid). Results The maximal colonic 18F-FDG uptake increased significantly in all separate segments after the use of metformin. There was no significant difference in energy expenditure or core body temperature after the use of metformin. There was no correlation between maximal colonic 18F-FDG uptake and energy expenditure or core body temperature. Conclusion Metformin significantly increases colonic 18F-FDG uptake, but this increased uptake is not associated with an increase in energy expenditure or core body temperature. Although the colon might be an important site of the glucose plasma lowering actions of metformin, this mechanism of action does not explain directly any associated weight loss. PMID:28464031

Spatiotemporal heterogeneity in carbon exchange at a restored peatland in Alberta, Canada

NASA Astrophysics Data System (ADS)

MacDonald, Scott; Strachan, Ian; Strack, Maria

2017-04-01

Boreal peatlands store a substantial portion of Earth's soil carbon, but the commercial peat extraction process upsets this carbon-sink dynamic. A best-practices restoration process has been developed that aims to return the vegetation and ecosystem functions of post-extraction peatlands. This includes the blocking and infilling of ditches, leveling of the peatland surface and re-introduction of vegetation through the moss layer transfer technique. The dynamics of carbon gas exchange in these restored peatlands are still poorly understood. We investigated ecosystem-scale and microscale carbon flux in a recently restored, post-extraction peatland near Seba Beach, Alberta, Canada. Two eddy covariance (EC) towers continuously measured CO2 and CH4 fluxes in hydrologically distinct parts of the peatland site. Here, we report on growing season measurements made during the fourth year following extraction. Regular static chamber measurements during June-August 2016 were also taken to study gas fluxes across an infilled drainage ditch on the site. Results suggest that if the peatland restoration process successfully returns high water table position, strong carbon uptake may be attained within several years of restoration. However, differences in peatland topography resulted spatial heterogeneity in carbon dynamics at this restored site. A gradient of revegetation success and attendant carbon-flux dynamics were observed, with much stronger net uptake of CO2 and substantial CH4 efflux measured at the tower with higher vegetation cover. Revegetation elsewhere was much sparser, and thus low CO2 uptake rates persisted at much of the peatland, though these conditions conversely inhibited substantial CH4 efflux. More broadly, the contrast in flux data between our two EC towers at the site suggests that attention be made to the selection of representative carbon flux values in similar restored peatlands.

Field measures show methanotroph sensitivity to soil moisture follows precipitation regime of the grassland sites across the US Great Plains

NASA Astrophysics Data System (ADS)

Koyama, A.; Webb, C. T.; Johnson, N. G.; Brewer, P. E.; von Fischer, J. C.

2015-12-01

Methane uptake rates are known to have temporal variation in response to changing soil moisture levels. However, the relative importance of soil diffusivity vs. methanotroph physiology has not been disentangled to date. Testing methanotroph physiology in the laboratory can lead to misleading results due to changes in the fine-scale habitat where methanotrophs reside. To assay the soil moisture sensitivity of methanotrophs under field conditions, we studied 22 field plots scattered across eight Great Plains grassland sites that differed in precipitation regime and soil moisture, making ca. bi-weekly measures during the growing seasons over three years. Quantification of methanotroph activity was achieved from chamber-based measures of methane uptake coincident with SF6-derived soil diffusivity, and interpretation in a reaction-diffusion model. At each plot, we also measured soil water content (SWC), soil temperature and inorganic nitrogen (N) contents. We also assessed methanotroph community composition via 454 sequencing of the pmoA gene. Statistical analyses showed that methanotroph activity had a parabolic response with SWC (concave down), and significant differences in the shape of this response among sites. Moreover, we found that the SWC at peak methanotroph activity was strongly correlated with mean annual precipitation (MAP) of the site. The sequence data revealed distinct composition patterns, with structure that was associated with variation in MAP and soil texture. These results suggest that local precipitation regime shapes methanotroph community composition, which in turn lead to unique sensitivity of methane uptake rates with soil moisture. Our findings suggest that methanotroph activity may be more accurately modeled when the biological and environmental responses are explicitly described.

Seasonal influences on ozone uptake and foliar injury to ponderosa and Jeffrey pines at a southern California site

Treesearch

Patrick J. Temple; Paul R. Miller

1998-01-01

Ambient ozone was monitored from 1992 to 1994 near a forested site dominated by mature Jeffrey and ponderosa pines (Pinus jeffrey Grev. & Balf. and Pinus ponderosa Dougl. ex Laws.) at 2,000 m in the San Bernardino Mountains of southern California. Ozone injury symptoms, including percent chlorotic mottle and foliage retention,...

A statistical approach to estimate O3 uptake of ponderosa pine in a mediterranean climate

Treesearch

N.E. Grulke; H.K. Preisler; C.C. Fan; W.A. Retzlaff

2002-01-01

In highly polluted sites, stomatal behavior is sluggish with respect to light, vapor pressure deficit, and internal CO2 concentration (Ci) and poorly described by existing models. Statistical models were developed to estimate stomatal conductance (gs) of 40-year-old ponderosa pine at three sites differing in pollutant exposure for the purpose of...

Noncompetitive blocking of human GLUT1 hexose transporter by methylxanthines reveals an exofacial regulatory binding site.

PubMed

Ojeda, Paola; Pérez, Alejandra; Ojeda, Lorena; Vargas-Uribe, Mauricio; Rivas, Coralia I; Salas, Monica; Vera, Juan Carlos; Reyes, Alejandro M

2012-09-01

Glucose transporter (GLUT)1 has become an attractive target to block glucose uptake in malignant cells since most cancer cells overexpress GLUT1 and are sensitive to glucose deprivation. Methylxanthines are natural compounds that inhibit glucose uptake; however, the mechanism of inhibition remains unknown. Here, we used a combination of binding and glucose transport kinetic assays to analyze in detail the effects of caffeine, pentoxifylline, and theophylline on hexose transport in human erythrocytes. The displacement of previously bound cytochalasin B revealed a direct interaction between the methylxanthines and GLUT1. Methylxanthines behave as noncompetitive blockers (inhibition constant values of 2-3 mM) in exchange and zero-trans efflux assays, whereas mixed inhibition with a notable uncompetitive component is observed in zero-trans influx assays (inhibition constant values of 5-12 mM). These results indicate that methylxanthines do not bind to either exofacial or endofacial d-glucose-binding sites but instead interact at a different site accessible by the external face of the transporter. Additionally, infinite-cis exit assays (Sen-Widdas assays) showed that only pentoxifylline disturbed d-glucose for binding to the exofacial substrate site. Interestingly, coinhibition assays showed that methylxanthines bind to a common site on the transporter. We concluded that there is a methylxanthine regulatory site on the external surface of the transporter, which is close but distinguishable from the d-glucose external site. Therefore, the methylxanthine moiety may become an attractive framework for the design of novel specific noncompetitive facilitative GLUT inhibitors.

Cellular Uptake of Chloroquine Is Dependent on Binding to Ferriprotoporphyrin IX and Is Independent of NHE Activity in Plasmodium falciparum

PubMed Central

Bray, Patrick G.; Janneh, Omar; Raynes, Kaylene J.; Mungthin, Mathirut; Ginsburg, Hagai; Ward, Stephen A.

1999-01-01

Here we provide definitive evidence that chloroquine (CQ) uptake in Plasmodium falciparum is determined by binding to ferriprotoporphyrin IX (FPIX). Specific proteinase inhibitors that block the degradation of hemoglobin and stop the generation of FPIX also inhibit CQ uptake. Food vacuole enzymes can generate cell-free binding, using human hemoglobin as a substrate. This binding accounts for CQ uptake into intact cells and is subject to identical inhibitor specificity. Inhibition of CQ uptake by amiloride derivatives occurs because of inhibition of CQ–FPIX binding rather than inhibition of the Na+/H+ exchanger (NHE). Inhibition of parasite NHE using a sodium-free medium does not inhibit CQ uptake nor does it alter the ability of amilorides to inhibit uptake. CQ resistance is characterized by a reduced affinity of CQ–FPIX binding that is reversible by verapamil. Diverse compounds that are known to disrupt lysosomal pH can mimic the verapamil effect. These effects are seen in sodium-free medium and are not due to stimulation of the NHE. We propose that these compounds increase CQ accumulation and overcome CQ resistance by increasing the pH of lysosomes and endosomes, thereby causing an increased affinity of binding of CQ to FPIX. PMID:10209030

Measurement and modeling of polychlorinated biphenyl bioaccumulation from sediment for the marine polychaete neanthes arenaceodentata and response to sorbent amendment

USGS Publications Warehouse

Janssen, E.M.-L.; Croteau, M.-N.; Luoma, S.N.; Luthy, R.G.

2010-01-01

Bioaccumulation rates of polychlorinated biphenyls (PCBs) for the marine polychaete Neanthes arenaceodentata were characterized, including PCB uptake rates from water and sediment, and the effect of sorbent amendment to the sediment on PCB bioavailability, organism growth, and lipid content. Physiological parameters were incorporated into a biodynamic model to predict contaminant uptake. The results indicate rapid PCB uptake from contaminated sediment and significant organism growth dilution during time-series exposure studies. PCB uptake from the aqueous phase accounted for less than 3% of the total uptake for this deposit-feeder. Proportional increase of gut residence time and assimilation efficiency as a consequence of the organism's growth was assessed by PCB uptake and a reactor theory model of gut architecture. Pulse-chase feeding and multilabeled stable isotope tracing techniques proved high sediment ingestion rates (i.e., 6?10 times of dry body weight per day) indicating that such deposit-feeders are promising biological indicators for sediment risk assessment. Activated carbon amendment reduced PCB uptake by 95% in laboratory experiments with no observed adverse growth effects on the marine polychaete. Biodynamic modeling explained the observed PCB body burdens for N. arenaceodentata, with and without sorbent amendment. ?? 2009 American Chemical Society.

Biogeochemical controls of uranium bioavailability from the dissolved phase in natural freshwaters

USGS Publications Warehouse

Croteau, Marie-Noele; Fuller, Christopher C.; Cain, Daniel J.; Campbell, Kate M.; Aiken, George R.

2016-01-01

To gain insights into the risks associated with uranium (U) mining and processing, we investigated the biogeochemical controls of U bioavailability in the model freshwater speciesLymnaea stagnalis (Gastropoda). Bioavailability of dissolved U(VI) was characterized in controlled laboratory experiments over a range of water hardness, pH, and in the presence of complexing ligands in the form of dissolved natural organic matter (DOM). Results show that dissolved U is bioavailable under all the geochemical conditions tested. Uranium uptake rates follow first order kinetics over a range encompassing most environmental concentrations. Uranium uptake rates in L. stagnalis ultimately demonstrate saturation uptake kinetics when exposure concentrations exceed 100 nM, suggesting uptake via a finite number of carriers or ion channels. The lack of a relationship between U uptake rate constants and Ca uptake rates suggest that U does not exclusively use Ca membrane transporters. In general, U bioavailability decreases with increasing pH, increasing Ca and Mg concentrations, and when DOM is present. Competing ions did not affect U uptake rates. Speciation modeling that includes formation constants for U ternary complexes reveals that the aqueous concentration of dicarbonato U species (UO2(CO3)2–2) best predicts U bioavailability to L. stagnalis, challenging the free-ion activity model postulate.

Enhancement of GABAergic transmission by zolpidem, an imidazopyridine with preferential affinity for type I benzodiazepine receptors.

PubMed

Biggio, G; Concas, A; Corda, M G; Serra, M

1989-02-28

The effect of zolpidem, an imidazopyridine derivative with high affinity at the type I benzodiazepine recognition site, on the function of the GABAA/ionophore receptor complex was studied in vitro. Zolpidem, mimicking the action of diazepam, increased [3H]GABA binding, enhanced muscimol-stimulated 36Cl- uptake and reduced [35S]TBPS binding in rat cortical membrane preparations. Zolpidem was less effective than diazepam on the above parameters. Zolpidem induced a lower increase of [3H]GABA binding (23 vs. 35%) and muscimol-stimulated 36Cl- uptake (22 vs. 40%) and a smaller decrease of [35S]TBPS binding (47 vs. 77%) than diazepam. The finding that zolpidem enhanced the function of GABAergic synapses with an efficacy qualitatively and quantitatively different from that of diazepam suggests that this compound is a partial agonist at the benzodiazepine recognition site. Thus, our results are consistent with the view that the biochemical and pharmacological profile of a benzodiazepine recognition site ligand reflects its efficacy to enhance GABAergic transmission. Whether the preferential affinity of zolpidem at the type I site is involved in its atypical biochemical and pharmacological profile remains to be clarified.

( sup 3 H)opipramol labels a novel binding site and sigma receptors in rat brain membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferris, C.D.; Hirsch, D.J.; Brooks, B.P.

1991-02-01

Opipramol (OP), a clinically effective antidepressant with a tricyclic structure, is inactive as an inhibitor of biogenic amine uptake. ({sup 3}H)Opipramol binds saturably to rat brain membranes (apparent KD = 4 nM, Bmax = 3 pmol/mg of protein). ({sup 3}H)Opipramol binding can be differentiated into haloperidol-sensitive and -resistant components, with Ki values for haloperidol of 1 nM (Bmax = 1 pmol/mg of protein) and 350 nM (Bmax = 1.9 pmol/mg of protein), respectively. The drug specificity of the haloperidol-sensitive component is the same as that of sigma receptors labeled with (+)-({sup 3}H)3-(3-hydroxyphenyl)-N-(1-propyl)piperdine. The haloperidol-resistant component does not correspond to anymore » known neurotransmitter receptor or uptake recognition site. It displays high affinity for phenothiazines and related structures such as perphenazine, clopenthixol, and flupenthixol, whose potencies are comparable to that of opipramol. Because certain of these drugs are more potent at the haloperidol-resistant opipramol site than in exerting any other action, it is possible that this opipramol-selective site may mediate their therapeutic effects.« less

Kd Values for Agricultural and Surface Soils for Use in Hanford Site Farm, Residential, and River Shoreline Scenarios

DOE Office of Scientific and Technical Information (OSTI.GOV)

Serne, R. Jeffrey

This report provides best estimate Kd values and a minimum and maximum range of Kd values to be used for agricultural soils and Columbia River bank sediments that exist today or would exist in the future when portions of the Hanford Site are released for farming, residential, and recreational use after the U. S. Department of Energy (DOE) completes clean up of defense waste on the site. The Kd values should be used to determine the fate and transport rates of contaminants and their availability for plant and animal uptake in selected non-groundwater scenarios included in Hanford Site environmental impactmore » statements, risk assessments and specific facility performance assessments. This report describes scenarios such as a small farm where drilling of a well inadvertently goes through buried waste and brings waste to the surface, allowing the tailings to become available for direct human exposure or incorporation into garden crops and farm animals used for food by the farm family. The Kd values recommended in this report can also be used to calculate sediment-water partitioning factors used to predict plant and animal uptake from interaction with the contaminated soil.« less

A biophysical approach using water deficit factor for daily estimations of evapotranspiration and CO2 uptake in Mediterranean environments

NASA Astrophysics Data System (ADS)

Helman, David; Lensky, Itamar M.; Osem, Yagil; Rohatyn, Shani; Rotenberg, Eyal; Yakir, Dan

2017-09-01

Estimations of ecosystem-level evapotranspiration (ET) and CO2 uptake in water-limited environments are scarce and scaling up ground-level measurements is not straightforward. A biophysical approach using remote sensing (RS) and meteorological data (RS-Met) is adjusted to extreme high-energy water-limited Mediterranean ecosystems that suffer from continuous stress conditions to provide daily estimations of ET and CO2 uptake (measured as gross primary production, GPP) at a spatial resolution of 250 m. The RS-Met was adjusted using a seasonal water deficit factor (fWD) based on daily rainfall, temperature and radiation data. We validated our adjusted RS-Met with eddy covariance flux measurements using a newly developed mobile lab system and the single active FLUXNET station operating in this region (Yatir pine forest station) at a total of seven forest and non-forest sites across a climatic transect in Israel (280-770 mm yr-1). RS-Met was also compared to the satellite-borne MODIS-based ET and GPP products (MOD16 and MOD17, respectively) at these sites.Results show that the inclusion of the fWD significantly improved the model, with R = 0.64-0.91 for the ET-adjusted model (compared to 0.05-0.80 for the unadjusted model) and R = 0.72-0.92 for the adjusted GPP model (compared to R = 0.56-0.90 of the non-adjusted model). The RS-Met (with the fWD) successfully tracked observed changes in ET and GPP between dry and wet seasons across the sites. ET and GPP estimates from the adjusted RS-Met also agreed well with eddy covariance estimates on an annual timescale at the FLUXNET station of Yatir (266 ± 61 vs. 257 ± 58 mm yr-1 and 765 ± 112 vs. 748 ± 124 gC m-2 yr-1 for ET and GPP, respectively). Comparison with MODIS products showed consistently lower estimates from the MODIS-based models, particularly at the forest sites. Using the adjusted RS-Met, we show that afforestation significantly increased the water use efficiency (the ratio of carbon uptake to ET) in this region, with the positive effect decreasing when moving from dry to more humid environments, strengthening the importance of drylands afforestation. This simple yet robust biophysical approach shows promise for reliable ecosystem-level estimations of ET and CO2 uptake in extreme high-energy water-limited environments.

Effect of ten quaternary ammonium cations on tetrachloromethane sorption to clay from water

USGS Publications Warehouse

Smith, J.A.

1990-01-01

The mineral surface of Wyoming bentonite (clay) was modified by replacing inorganic ions by each of 10 quaternary ammonium compounds, and tetrachloromethane sorption to the modified sorbents from water was studied. Tetrachloromethane sorption from solution to clay modified with tetramethyl-, tetraethyl-, benzyltrimethyl-, or benzyltriethylammonium cations generally is characterized by relatively high solute uptake, isotherm nonlinearity, and competitive sorption (with trichloroethene as the competing sorbate). For these sorbents, the ethyl functional groups yield reduced sorptive capacity relative to methyl groups, whereas the benzyl group appears to have a similar effect on sorbent capacity as the methyl group. Sorption of tetrachloromethane to clay modified with dodecyldimethyl(2-phenoxyethyl)-, dodecyltrimethyl-, tetradecyltrimethyl-, hexadecyltrimethyl-, or benzyldimethylhexadecylammonium bromide is characterized by relatively low solute uptake, isotherm linearity, and noncompetitive sorption. For these sorbents, an increase in the size of the nonpolar functional group(s) causes an increase in the organic carbon normalized sorption coefficient (Koc). No measurable uptake of tetrachloromethane sorption by the unmodified clay or clay modified by ammonium bromide was observed. ?? 1990 American Chemical Society.

Micro-Spectroscopic Chemical Imaging of Individual Identified Marine Biogenic and Ambient Organic Ice Nuclei (Invited)

NASA Astrophysics Data System (ADS)

Knopf, D. A.; Alpert, P. A.; Wang, B.; OBrien, R. E.; Moffet, R. C.; Aller, J. Y.; Laskin, A.; Gilles, M.

2013-12-01

Atmospheric ice formation represents one of the least understood atmospheric processes with important implications for the hydrological cycle and climate. Current freezing descriptions assume that ice active sites on the particle surface initiate ice nucleation, however, the nature of these sites remains elusive. Here, we present a new experimental method that allows us to relate physical and chemical properties of individual particles with observed water uptake and ice nucleation ability using a combination of micro-spectroscopic and optical single particle analytical techniques. We apply this method to field-collected particles and particles generated via bursting of bubbles produced by glass frit aeration and plunging water impingement jets in a mesocosm containing artificial sea water and bacteria and/or phytoplankton. The most efficient ice nuclei (IN) within a particle population are identified and characterized. Single particle characterization is achieved by computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy. A vapor controlled cooling-stage coupled to an optical microscope is used to determine the onsets of water uptake, immersion freezing, and deposition ice nucleation of the individual particles as a function of temperature (T) as low as 200 K and relative humidity (RH) up to water saturation. In addition, we perform CCSEM/EDX to obtain on a single particle level the elemental composition of the entire particle population. Thus, we can determine if the IN are exceptional in nature or belong to a major particle type class with respect to composition and size. We find that ambient and sea spray particles are coated by organic material and can induce ice formation under tropospheric relevant conditions. Micro-spectroscopic single particle analysis of the investigated particle samples invokes a potential paradigm shift: Individual ice nucleating particle composition indicates that IN are similar to the majority of particles in the population and not exceptional. This suggests that composition alone may not be a determinant for IN identification. Furthermore, the results suggest that particle abundance may be a crucial parameter for IN efficiency when predicting cloud glaciation processes. These findings would have important consequences for cloud modeling, laboratory ice nucleation experiments, and field measurements.

A primary fish gill cell culture model to assess pharmaceutical uptake and efflux: Evidence for passive and facilitated transport

PubMed Central

Stott, Lucy C.; Schnell, Sabine; Hogstrand, Christer; Owen, Stewart F.; Bury, Nic R.

2015-01-01

The gill is the principle site of xenobiotic transfer to and from the aqueous environment. To replace, refine or reduce (3Rs) the large numbers of fish used in in vivo uptake studies an effective in vitro screen is required that mimics the function of the teleost gill. This study uses a rainbow trout (Oncorhynchus mykiss) primary gill cell culture system grown on permeable inserts, which tolerates apical freshwater thus mimicking the intact organ, to assess the uptake and efflux of pharmaceuticals across the gill. Bidirectional transport studies in media of seven pharmaceuticals (propranolol, metoprolol, atenolol, formoterol, terbutaline, ranitidine and imipramine) showed they were transported transcellularly across the epithelium. However, studies conducted in water showed enhanced uptake of propranolol, ranitidine and imipramine. Concentration-equilibrated conditions without a concentration gradient suggested that a proportion of the uptake of propranolol and imipramine is via a carrier-mediated process. Further study using propranolol showed that its transport is pH-dependent and at very low environmentally relevant concentrations (ng L−1), transport deviated from linearity. At higher concentrations, passive uptake dominated. Known inhibitors of drug transport proteins; cimetidine, MK571, cyclosporine A and quinidine inhibited propranolol uptake, whilst amantadine and verapamil were without effect. Together this suggests the involvement of specific members of SLC and ABC drug transporter families in pharmaceutical transport. PMID:25544062

Defect Creation by Linker Fragmentation in Metal-Organic Frameworks and Its Effects on Gas Uptake Properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barin, G; Krungleviciute, V; Gutov, O

2014-07-07

We successfully demonstrate an approach based on linker fragmentation to create defects and tune the pore volumes and surface areas of two metal-organic frameworks, NU-125 and HKUST-1, both of which feature copper paddlewheel nodes. Depending on the linker fragment composition, the defect can be either a vacant site or a functional group that the original linker does not have. In the first case, we show that both surface area and pore volume increase, while in the second case they decrease. The effect of defects on the high-pressure gas uptake is also studied over a large temperature and pressure range formore » different gases. We found that despite an increase in pore volume and surface area in structures with vacant sites, the absolute adsorption for methane decreases for HKUST-1 and slightly increases for NU-125. However, the working capacity (deliverable amount between 65 and 5 bar) in both cases remains similar to parent frameworks due to lower uptakes at low pressures. In the case of NU-125, the effect of defects became more pronounced at lower temperatures, reflecting the greater surface areas and pore volumes of the altered forms.« less

Uptake of explosives from contaminated soil by existing vegetation at the Iowa Army Ammunition Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schneider, J.F.; Zellmer, S.D.; Tomczyk, N.A.

This study examines the uptake of explosives by existing vegetation growing in soils contaminated with 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitro-3,5-triazine (RDX) in three areas at the Iowa Army Ammunition Plant (IAAP). To determine explosives uptake under natural environmental conditions, existing plant materials and soil from the root zone were sampled at different locations in each area, and plant materials were separated by species. Standard methods were used to determine the concentrations of explosives, their derivatives, and metabolites in the soil samples. Plant materials were also analyzed. The compound TNT was not detected in the aboveground portion of plants, and vegetation growingmore » on TNT-contaminated soils is not considered a health hazard. However, soil and plant roots may contain TNT degradation products that may be toxic; hence, their consumption is not advised. The compound RDX was found in the tops and roots of plants growing on RDX-contaminated soils at all surveyed sites. Although RDX is not a listed carcinogen, several of its potentially present degradation products are carcinogens. Therefore, the consumption of any plant tissues growing on RDX-contaminated sites should be considered a potential health hazard.« less

Fivefold increase of hydrogen uptake in MOF74 through linker decorations

NASA Astrophysics Data System (ADS)

Arter, C. A.; Zuluaga, S.; Harrison, D.; Welchman, E.; Thonhauser, T.

2016-10-01

We present ab initio results for linker decorations in Mg-MOF74, i.e., attaching various metals M =Li, Na, K, Sc, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Pd, Ag, and Pt near the ring of the linker, creating new strong adsorption sites and thus maximizing small-molecule uptake. We find that in most cases these decorations influence the overall form and structure of Mg-MOF74 only marginally. After the initial screening, we chose metals that bind favorably to the linker and further investigated adsorption of H2,CO2, and H2O for M =Li , Na, K, and Sc. For the case of H2 we show that up to 24 additional guest molecules can be adsorbed in the metal-organic framework (MOF) unit cell, with binding energies comparable to the original open-metal sites at the six corners of the channel. This leads to a fivefold increase of the molecule uptake in Mg-MOF74, with tremendous impact on many applications in general and hydrogen storage in particular, where the gravimetric hydrogen density increases from 1.63 to 7.28 mass % and the volumetric density increases from 15.10 to 75.50 g H2L-1 .

Performance of deep-rooted phreatophytic trees at a site containing total petroleum hydrocarbons.

PubMed

Ferro, Ari M; Adham, Tareq; Berra, Brett; Tsao, David

2013-01-01

Poplar and willow tree stands were installed in 2003 at a site in Raleigh, North Carolina containing total petroleum hydrocarbon - contaminated groundwater. The objective was groundwater uptake and plume control. The water table was 5 to 6 m below ground surface (bgs) and therefore methods were used to encourage deep root development. Growth rates, rooting depth and sap flow were measured for trees in Plot A located in the center of the plume and in Plot B peripheral to the plume. The trees were initially sub-irrigated with vertically installed drip-lines and by 2005 had roots 4 to 5 m bgs. Water balance calculations suggested groundwater uptake. In 2007, the average sap flow was higher for Plot B (approximately 59 L per day per tree) than for Plot A (approximately 23 L per day per tree), probably as a result of TPH-induced stress in Plot A. Nevertheless, the estimated rate of groundwater uptake for Plot A was sufficient, relative to the calculated rate of groundwater flux beneath the stand, that a high level of plume control was achieved based on MODFLOW modeling results. Down-gradient groundwater monitoring wells installed in late 2011 should provide quantitative data for plume control.

Models for root water uptake under deficit irrigation

NASA Astrophysics Data System (ADS)

Lazarovitch, Naftali; Krounbi, Leilah; Simunek, Jirka

2010-05-01

Modern agriculture, with its dependence on irrigation, fertilizers, and pesticide application, contributes significantly to the water and solute influx through the soil into the groundwater, specifically in arid areas. The quality and quantity of this water as it passes through the vadose zone is influenced primarily by plant roots. Root water uptake is a function of both a physical root parameter, commonly referred to as the root length density, and the soil water status. The location of maximum water uptake in a homogenous soil profile of uniform water content and hydraulic conductivity occurs in the soil layer containing the largest root length density. Under field conditions, in a drying soil, plants are both subject to, and the source of, great spatial variability in the soil water content. The upper soil layers containing the bulk of the root zone are usually the most water depleted, while the deeper regions of the soil profile containing fewer roots are wetter. Changes in the physiological functioning of plants have been shown to result from extended periods of water stress, but the short term effects of water stress on root water uptake are less well understood. While plants can minimize transpiration and the resulting growth rates under limiting conditions to conserve water, many plants maintain a constant potential transpiration rate long after the commencement of the drying process. Compensatory uptake, whereby plants respond to non-uniform, limiting conditions by increasing water uptake from areas in the root zone characterized by more favorable conditions, is one such mechanism by which plants sustain potential transpiration rates in drying soils. The development of models which accurately characterize temporal and spatial root water uptake patterns is important for agricultural resource optimization, upon which subsequent management decisions affecting resource conservation and environmental pollution are based. Numerical simulations of root water uptake in various irrigation and fertilization regimes provide a much-needed alternative to tiring and expensive field work. These simulations can aid in raising agricultural water use efficiency while preserving soil and water resources. In this research, controlled lab experiments were carried out in soil-packed lysimeters designed for plant cultivation. Both the water balance of the growing plants as well as the temporary matric head distribution in the soil profile were calculated and measured. The experiment was conducted with sweet sorghum grown in two different soil profiles with different hydraulic properties. The experiment provided the data necessary to calculate the parameters of various models used to simulate root water uptake, by using an inverse solution method imbedded in the HYDRUS-1D code. The observed increase in uptake from the wetter soil regions under drying conditions, as measured and calculated, sheds light on the dominant role of soil hydraulic properties over the root distribution, and consequently root water uptake.

WZB117 (2-Fluoro-6-(m-hydroxybenzoyloxy) Phenyl m-Hydroxybenzoate) Inhibits GLUT1-mediated Sugar Transport by Binding Reversibly at the Exofacial Sugar Binding Site.

PubMed

Ojelabi, Ogooluwa A; Lloyd, Kenneth P; Simon, Andrew H; De Zutter, Julie K; Carruthers, Anthony

2016-12-23

WZB117 (2-fluoro-6-(m-hydroxybenzoyloxy) phenyl m-hydroxybenzoate) inhibits passive sugar transport in human erythrocytes and cancer cell lines and, by limiting glycolysis, inhibits tumor growth in mice. This study explores how WZB117 inhibits the erythrocyte sugar transporter glucose transport protein 1 (GLUT1) and examines the transporter isoform specificity of inhibition. WZB117 reversibly and competitively inhibits erythrocyte 3-O-methylglucose (3MG) uptake with K i (app) = 6 μm but is a noncompetitive inhibitor of sugar exit. Cytochalasin B (CB) is a reversible, noncompetitive inhibitor of 3MG uptake with K i (app) = 0.3 μm but is a competitive inhibitor of sugar exit indicating that WZB117 and CB bind at exofacial and endofacial sugar binding sites, respectively. WZB117 inhibition of GLUTs expressed in HEK293 cells follows the order of potency: insulin-regulated GLUT4 ≫ GLUT1 ≈ neuronal GLUT3. This may explain WZB117-induced murine lipodystrophy. Molecular docking suggests the following. 1) The WZB117 binding envelopes of exofacial GLUT1 and GLUT4 conformers differ significantly. 2) GLUT1 and GLUT4 exofacial conformers present multiple, adjacent glucose binding sites that overlap with WZB117 binding envelopes. 3) The GLUT1 exofacial conformer lacks a CB binding site. 4) The inward GLUT1 conformer presents overlapping endofacial WZB117, d-glucose, and CB binding envelopes. Interrogating the GLUT1 mechanism using WZB117 reveals that subsaturating WZB117 and CB stimulate erythrocyte 3MG uptake. Extracellular WZB117 does not affect CB binding to GLUT1, but intracellular WZB117 inhibits CB binding. These findings are incompatible with the alternating conformer carrier for glucose transport but are consistent with either a multisubunit, allosteric transporter, or a transporter in which each subunit presents multiple, interacting ligand binding sites. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

WZB117 (2-Fluoro-6-(m-hydroxybenzoyloxy) Phenyl m-Hydroxybenzoate) Inhibits GLUT1-mediated Sugar Transport by Binding Reversibly at the Exofacial Sugar Binding Site*

PubMed Central

Ojelabi, Ogooluwa A.; Lloyd, Kenneth P.; Simon, Andrew H.; De Zutter, Julie K.; Carruthers, Anthony

2016-01-01

WZB117 (2-fluoro-6-(m-hydroxybenzoyloxy) phenyl m-hydroxybenzoate) inhibits passive sugar transport in human erythrocytes and cancer cell lines and, by limiting glycolysis, inhibits tumor growth in mice. This study explores how WZB117 inhibits the erythrocyte sugar transporter glucose transport protein 1 (GLUT1) and examines the transporter isoform specificity of inhibition. WZB117 reversibly and competitively inhibits erythrocyte 3-O-methylglucose (3MG) uptake with Ki(app) = 6 μm but is a noncompetitive inhibitor of sugar exit. Cytochalasin B (CB) is a reversible, noncompetitive inhibitor of 3MG uptake with Ki(app) = 0.3 μm but is a competitive inhibitor of sugar exit indicating that WZB117 and CB bind at exofacial and endofacial sugar binding sites, respectively. WZB117 inhibition of GLUTs expressed in HEK293 cells follows the order of potency: insulin-regulated GLUT4 ≫ GLUT1 ≈ neuronal GLUT3. This may explain WZB117-induced murine lipodystrophy. Molecular docking suggests the following. 1) The WZB117 binding envelopes of exofacial GLUT1 and GLUT4 conformers differ significantly. 2) GLUT1 and GLUT4 exofacial conformers present multiple, adjacent glucose binding sites that overlap with WZB117 binding envelopes. 3) The GLUT1 exofacial conformer lacks a CB binding site. 4) The inward GLUT1 conformer presents overlapping endofacial WZB117, d-glucose, and CB binding envelopes. Interrogating the GLUT1 mechanism using WZB117 reveals that subsaturating WZB117 and CB stimulate erythrocyte 3MG uptake. Extracellular WZB117 does not affect CB binding to GLUT1, but intracellular WZB117 inhibits CB binding. These findings are incompatible with the alternating conformer carrier for glucose transport but are consistent with either a multisubunit, allosteric transporter, or a transporter in which each subunit presents multiple, interacting ligand binding sites. PMID:27836974

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kahl, S.B.

Although significant progress toward the application of boronated LDL for site selective boron drug delivery has been made during the past year, the loss of our animal and cell culture testing site at WSU has seriously hampered progress on this project. Results are reported of one in vivo biodistribution study in B16BL6-bearing mice and a series of in vitro studies that demonstrate very substantial uptake of boronated LDL in certain cell lines. The influence of 17{alpha}-ethinyl estradiol (EE) on cellular uptake has also been probed. Most significantly LDL loaded with HC was demonstrated to be taken up with exceptional ariditymore » in several lines. Significant progress has also been made in the development of a rapid infrared analysis of boron in boronated LDL solution, which may be useful for clinical BNCT studies in Finland.« less

Tc-99m imaging in thyroidectomized differentiated thyroid cancer patients immediately before I-131 treatment.

PubMed

Tsai, Chi-Jung; Cheng, Cheng-Yi; Shen, Daniel Hueng-Yuan; Kuo, Shou Jen; Wang, Lien-Yen; Lee, Chiang-Hsuan; Wang, Jhi-Joung; Chang, Ming-Che; Huang, Wen-Sheng

2016-02-01

The aim of this study was to evaluate the clinical role of technetium-99m pertechnetate (Tc-99m) imaging in thyroidectomized differentiated thyroid cancer patients immediately before radioiodine-131 (I-131) treatment (Tx). Eighty-six consecutive post-total-thyroidectomy patients (15 men, 71 women; mean age: 46.8 years) with pathologically diagnosed differentiated thyroid cancer were retrospectively studied. Tc-99m imaging immediately before I-131 Tx using both patient-based and lesion-based measurements were analyzed and were further compared with those of post-Tx I-131 whole-body scans. For patients with unequivocally positive Tc-99m uptake, the sensitivity was 77% (patient-based) and 59% (site-based). The positive predictive value (PPV) was 100% for both patient-based and site-based measurements. If equivocal Tc-99m uptake was counted as positive, the sensitivity was 83 and 67%, and the PPV was 100 and 99% for patient-based and site-based measurements, respectively. (a) To increase sensitivity yet maintaining high PPV, equivocal Tc-99m uptake should be considered a positive finding. (b) The nearly 100% PPV of Tc-99m imaging immediately before I-131 Tx for remnant detection suggests that Tc-99m imaging not only serves as an alternative to low-dose I-131 scanning in the low-risk post-thyroidectomy patients but also provides a clue for the subsequent I-131 therapeutic dosage and even for the outcome prediction.

Novel single skeletal muscle fiber analysis reveals a fiber type-selective effect of acute exercise on glucose uptake.

PubMed

Cartee, Gregory D; Arias, Edward B; Yu, Carmen S; Pataky, Mark W

2016-11-01

One exercise session can induce subsequently elevated insulin sensitivity that is largely attributable to greater insulin-stimulated glucose uptake by skeletal muscle. Because skeletal muscle is a heterogeneous tissue comprised of diverse fiber types, our primary aim was to determine exercise effects on insulin-independent and insulin-dependent glucose uptake by single fibers of different fiber types. We hypothesized that each fiber type featuring elevated insulin-independent glucose uptake immediately postexercise (IPEX) would be characterized by increased insulin-dependent glucose uptake at 3.5 h postexercise (3.5hPEX). Rat epitrochlearis muscles were isolated and incubated with 2-[ 3 H]deoxyglucose. Muscles from IPEX and sedentary (SED) controls were incubated without insulin. Muscles from 3.5hPEX and SED controls were incubated ± insulin. Glucose uptake (2-[ 3 H]deoxyglucose accumulation) and fiber type (myosin heavy chain isoform expression) were determined for single fibers dissected from the muscles. Major new findings included the following: 1) insulin-independent glucose uptake was increased IPEX in single fibers of each fiber type (types I, IIA, IIB, IIBX, and IIX), 2) glucose uptake values from insulin-stimulated type I and IIA fibers exceeded the values for the other fiber types, 3) insulin-stimulated glucose uptake for type IIX exceeded IIB fibers, and 4) the 3.5hPEX group vs. SED had greater insulin-stimulated glucose uptake in type I, IIA, IIB, and IIBX but not type IIX fibers. Insulin-dependent glucose uptake was increased at 3.5hPEX in each fiber type except for IIX fibers, although insulin-independent glucose uptake was increased IPEX in all fiber types (including type IIX). Single fiber analysis enabled the discovery of this fiber type-related difference for postexercise, insulin-stimulated glucose uptake. Copyright © 2016 the American Physiological Society.

Spontaneous plant colonization of brownfield soil and sludges and effects on substrate properties and pollutants mobility

NASA Astrophysics Data System (ADS)

Rocco, Claudia; Agrelli, Diana; Gonzalez, Maria Isabel; Mingo, Antonio; Motti, Riccardo; Stinca, Adriano; Coppola, Ida; Adamo, Paola

2017-04-01

This work was done on brownfield soil and sludges from a dismantled steel plant, moderately polluted by heavy metals (mainly Pb and Zn), 1) to analyzed the effects of substrate properties and environmental conditions on spontaneous vegetation; 2) to assess changes in the chemical properties of soils and sludges, with particular reference to the mobility and bioavailability of pollutants, induced by spontaneous plants revegetation. From 2006 to 2011, spontaneous plant colonization was monitored in the presence or absence of acidic peat both inside the degraded brownfield site and after transferal into a nearby Oak Park environment. During the five experimental years the vegetation growth was monitored using phytosociological method and data analyzed statistically. Both substrates, before and after plant growth, were analyzed for main chemical properties. Metals mobility and bioavailability was assessed using single (H2O; DTPA) and sequential extractions (EU-BCR). At the end of the experiment, plant ability to uptake metal was evaluated on selected species. Overall, 57 plant species grew healthily on the substrates. The combination of soil and sludges with peat resulted in an effective revegetation with a sensible increasing of plants biomass. Most of the species were found in the park (91%), showing plant colonization was mainly affected by the immediate environment rather than by substrate properties. Furthermore, after the five years, the substrate properties (pH, O.C.) were slightly affected by plant growth and, although metal pollutants in both substrates are characterized by low water solubility and DTPA availability, after plants growth an increase (even if not significant) of rhizospheric Cu, Fe, Mn and Zn solubility in H2O was detected. Metals speciation indicated a low risk of Pb and Zn mobility being either largely trapped in the mineralogical structure of oxides and silicates and occluded in easily reducible manganese or iron oxides. Restricted metal uptake and tissue accumulation by selected plants were measured, with only Daucus carota showing a higher ability to translocate metals to shoots (shoot/root metal concentration quotient >1 with peat). Water always underestimated plant uptake, while DTPA and sequential extractions better predicted Pb and Zn uptake. Phytostabilization with native plant species can be an efficient, environmentally appropriate and low cost technology for rehabilitation of industrial sites. The addition of organic matter may help the spontaneous re-vegetation and could facilitate the recovery of degraded environment. However, the changing induced by peat and plants might induced a solubilization of metal pollutants. A continuous monitoring of the potential changes of pollutants mobility-bioavailability by plants is crucial to prevent risks to the environment and human health. Key words: Heavy metals, phytoremediation, Peat addition, bioavailability, sequential extractions

Quantification of tomato and Arabidopsis mobile RNAs trafficking into the parasitic plant Cuscuta pentagona.

PubMed

LeBlanc, Megan; Kim, Gunjune; Patel, Beneeta; Stromberg, Verlyn; Westwood, James

2013-12-01

The cross-species movement of mRNA from hosts to the parasitic plant Cuscuta pentagona has been reported previously, but has not been characterized quantitatively or with attention to uptake patterns and the fate of specific mRNAs. Real-time PCR and RNA-Seq approaches were used to identify and characterize mobile transcripts from tomato and Arabidopsis hosts into C. pentagona. Tomato transcripts of Gibberellic Acid Insensitive (SlGAI) and Cathepsin D Proteinase Inhibitor (SlPI) differed significantly in the rate of uptake into the parasite, but were then distributed over the length of the parasite shoot. When parasite shoots were detached from the hosts, the SlPI transcript concentrations in the parasite showed the greatest decrease within the first 8 h. Arabidopsis transcripts also varied in mobility into the parasite, and assay of specific regions of a Salt-inducible Zinc Finger Protein (AtSZF1) transcript revealed distinct patterns of abundance in the parasite. The uptake and distribution of host mRNAs into C. pentagona appears to vary among mRNAs, and perhaps even with the region of the mRNA under investigation. We propose that mRNAs traffic into the parasite via multiple routes, or that other mechanisms for selective uptake and mobility exist between host and parasite. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Preparation and characterization of nanocomposite polymer electrolytes poly(vinylidone fluoride)/nanoclay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahmawati, Suci A.; Sulistyaningsih,; Putro, Alviansyah Z. A.

2016-02-08

Polymer electrolytes are defined as semi solid electrolytes used as separator in lithium ion battery. Separator used as medium for transfer ions and to prevent electrical short circuits in battery cells. To obtain the optimal battery performance, separator with high porosity and electrolyte uptake is required. This can reduce the resistance in the transfer of ions between cathode and anode. The main objective of this work is to investigate the impact of different solvent (Dimethyl acetamide (DMAc), N-methyl-2-pyrrolidone (NMP) and dimethyl formamide (DMF)), pore forming agent poly(vinylpyrolidone) (PVP) and nanoclay as filler in addition of membrane using phase inversion methodmore » on the morphology, porosity, electrolyte uptake and degree of crystallinity. The membrane was prepared by the phase inversion method by adding PVP and Nanoclay using different solvents. The phase inversion method was prepared by dissolving Nanoclay and PVP in solvent for 1-2 hours, and then add the PVDF with stirring for 4 hours at 60°C. The membranes were characterized by porosity test, electrolyte uptake test, scanning electron microscope (SEM), and X-ray diffraction (XRD). The results showed that DMAc as solvent gives the highest value of porosity and electrolyte uptake. The addition of nanoclay and PVP enlarge the size of the pores and reduce the degree of crystallinity. So, the usage of DMAc as solvent is better than NMP or DMF.« less

SITE CHARACTERIZATION LIBRARY VERSION 3.0

EPA Science Inventory

The Site Characterization Library is a CD that provides a centralized, field-portable source for site characterization information. Version 3 of the Site Characterization Library contains additional (from earlier versions) electronic documents and computer programs related to th...

Arsenic Transport in Rice and Biological Solutions to Reduce Arsenic Risk from Rice

PubMed Central

Chen, Yanshan; Han, Yong-He; Cao, Yue; Zhu, Yong-Guan; Rathinasabapathi, Bala; Ma, Lena Q.

2017-01-01

Rice (Oryza sativa L.) feeds ∼3 billion people. Due to the wide occurrence of arsenic (As) pollution in paddy soils and its efficient plant uptake, As in rice grains presents health risks. Genetic manipulation may offer an effective approach to reduce As accumulation in rice grains. The genetics of As uptake and metabolism have been elucidated and target genes have been identified for genetic engineering to reduce As accumulation in grains. Key processes controlling As in grains include As uptake, arsenite (AsIII) efflux, arsenate (AsV) reduction and AsIII sequestration, and As methylation and volatilization. Recent advances, including characterization of AsV uptake transporter OsPT8, AsV reductase OsHAC1;1 and OsHAC1;2, rice glutaredoxins, and rice ABC transporter OsABCC1, make many possibilities to develop low-arsenic rice. PMID:28298917

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guha, A.; Prasad, G.C.; Udupa, K.N.

Scintillography and autoradiography were used to study the healing of humeral fractures in rats injected with Sr/sup 85/. Among various agents studied for an influence on the rate of fracture healing, the total extract of the herb Cissus quadrangularis was tested. In both controls and animals receiving C. quadrangularis extract there was demineralization of the fractured bone at the site of fracture. In the treated group, there was a somewhat earlier rise in Sr/ sup 85/ uptake just after the first injection. Thereafter, uptake again became high, similar to the control samples from the 6th day onward. The maximum uptakemore » of control bone was found to be around the 19th day after fracturing, while in the treated group, maximum uptake was on 15th day. Though there was a minor difference in the period of maximum uptake between treated and control bone, the rate of uptake in the treated sample was markedly higher than that of the control sample. The fall of Sr/sup 85/ uptake in the treated bone was very rapid, whereas in the untreated animals it was more gradual. All these findings on the uptake of Sr/sup 85/ as measured by a G-M counter, corroborated x-ray pictures and gross autoradiography at different stages of fracture healing. The radiological and autoradiographic findings also clearly showed that the healing in the treated group was quicker than in the controls. Furthermore, the callus in the treated animals underwent remodeling processes much earlier than in the nontreated ones. It is concluded that if the uptake of Sr in the treated andimals is greater thand in the control samples at the site of fracture, healing activity is more pronounced. However, studies on patients have shown that the uptake of Sr/sup 85/ alone in the fractured region may not give an accurate picture of the healing processes. Thus, at the end of first week after fractures, accretion rate of Ca reached a peak and thereafter remained higher than normal throughout the period of healing. But when these results were compared with x-ray pictures, it was observed that the accretion rate in poorly uniting fractures did not diifer from that of normally healing fractures, so that in interpreting the rate of healing by the uptake of Sr/sup 85/, radiography is also required to make the correct assessment of the status of fracture healing. The Sr/sup 85/ uptake curves show that the uptake pattern can be divided into three definite phases. ln the first phase, which lasts for six days, there is and enormous amount of decalcification from the broken fragments of bone possibly due to increased vascularity of the region, and also to the increased accumulation of mucopolysaccharides locally. In the second phase, which lasts for another 8 to 12 days, rapid increase in the accretion of Ca as evidenced by increase in the uptake of Sr/sup 85/ noted. During the 2nd phase, histologic studies indicated that large amounts of collagen fibers appear, which possibly combine with all the available Ca salts there. The third phase shows a rapid fall of Sr/sup 85/ uptake, indicating that the callus formed in the second phase is rapidly being remodeled. (BBB)« less

SPECT/CT tracer uptake is influenced by tunnel orientation and position of the femoral and tibial ACL graft insertion site.

PubMed

Hirschmann, Michael T; Mathis, Dominic; Rasch, Helmut; Amsler, Felix; Friederich, Niklaus F; Arnold, Markus P

2013-02-01

SPECT/CT is a hybrid imaging modality, which combines a 3D scintigraphy (SPECT) and a conventional computerised tomography (CT). SPECT/CT allows accurate anatomical localisation of metabolic tracer activity. It allows the correlation of surgical factors such as tunnel position and orientation with mechanical alignment, clinical outcome and biological factors. The purpose of this study was to investigate whether the SPECT/CT tracer uptake (intensity and distribution) correlates with the stability and laxity of the knee joint and the position and orientation of the tibial and femoral tunnels in patients after anterior cruciate ligament (ACL) reconstruction. A consecutive series of knees (n=66), with symptoms of pain and/or instability after ACL reconstruction were prospectively evaluated using clinical examination and 99mTc-HDP-SPECT/CT. Clinical laxity testing was performed using the Rolimeter (Ormed, Freiburg, Germany) including Lachman testing (0-2 mm, 3-5 mm, 6-10 mm, >10 mm), anterior drawer test (0-2 mm, 3-5 mm, 6-10 mm, >10 mm), pivot shift test (positive versus negative) and patient-based subjective instability (yes versus no). For analysis of SPECT/CT tracer uptake a previously validated SPECT/CT localisation scheme consisting of 17 tibial, nine femoral and four patellar regions on standardised axial, coronal, and sagittal slices was used. The tracer activity on SPECT/CT was localised and recorded using a 3D volumetric and quantitative analysis software. Mean, standard deviation, minimum and maximum of grading for each area of the localisation scheme were recorded. The position and orientation of the tibial and femoral tunnel was assessed using a previously published method on 3D-CT. Correlation of instability, pivot shift as well as clinical laxity testing with 99mTc-HDP-SPECT/CT tracer uptake intensity and distribution showed no significant correlation. 99mTc-HDP-SPECT/CT tracer uptake correlated significantly with the position and orientation of the ACL graft. A more horizontal femoral graft position showed significantly increased tracer uptake within the superior and posterior femoral regions. A more posteriorly-placed femoral insertion site showed significantly more tracer uptake within the femoral and tibial tunnel regions. A more vertical or a less medial tibial tunnel orientation showed significant increased uptake within the tibial and femoral tunnel regions. A more anterior tibial tunnel position showed significantly more tracer uptake in the femoral and tibial tunnel regions as well as the entire tibiofemoral joint. SPECT/CT tracer uptake intensity and distribution showed a significant correlation with the femoral and tibial tunnel position and orientation in patients with symptomatic knees after ACL reconstruction. No correlation was found with stability or clinical laxity. SPECT/CT tracer uptake distribution has the potential to give us important information on joint homeostasis and remodelling after ACL reconstruction. It might help to predict ACL graft failure and improve our surgical ACL reconstruction technique in finding the optimal tunnel and graft position and orientation.

Field measurements on the exchange of carbonyl sulfide between lichens and the atmosphere

NASA Astrophysics Data System (ADS)

Kuhn, U.; Wolf, A.; Gries, C.; , T. H. Nash, III; Kesselmeier, J.

The exchange of carbonyl sulfide (COS) between lichens and the atmosphere was investigated under natural field conditions. Using dynamic enclosures flushed with ambient air, we demonstrate that lichens act as a major sink for atmospheric COS in the investigated ecosystem. Diel courses of the exchange are shown in an open oak woodland ecosystem at a rural site in central California. The measurements were distributed over a variety of weather conditions during the dry (May/June) and the wet season (Nov/Dec). The physiological parameters (CO 2 exchange and thallus hydration status) plus environmental variables (temperature, irradiance, atmospheric humidity and ambient COS mixing ratio) were recorded. Lichens are capable of continuous uptake of COS in the dark as well as in the light, depending mainly on their moisture status. Results indicate that the uptake is additionally dependent on temperature and COS ambient mixing ratio. Enzyme inactivation by high temperature denaturation demonstrate that the uptake is under physiological control. Light and thus photosynthetic activity do not have a direct influence on the uptake rate. Under these field investigations the COS uptake on a dry weight basis ranged between 0.015 and 0.071 pmol g-1 s-1. On a thallus surface area basis the sink strength is comparable to the uptake by higher vegetation.

Conductive choline transport by alveolar epithelial plasma membrane vesicles.

PubMed

Oelberg, D G; Xu, F

1998-11-01

Choline is an important substrate in alveolar epithelia for both surfactant production and cellular maintenance. The underlying mechanisms of uptake and sites of membrane transport remain uncertain. To test the hypothesis that choline transport occurs at the basolateral side of alveolar epithelia by both Na+-independent and -dependent mechanisms, plasma membrane vesicles were prepared from the apical and basolateral membranes of mature porcine type II pneumocytes. Choline+ transport was assayed by uptake of [3H]choline+ by enriched apical or basolateral vesicles. In the presence of imposed, inside-negative charge gradients, basolateral vesicles exhibited early overshoot of [3H]choline+ uptake unaffected by the presence or absence of external Na+ (541 +/- 53 vs 564 +/- 79 pmol/mg protein (NS)). High sensitivity to hemicholinium-3 was observed in the presence or absence of Na+. In the absence of inside-negative charge gradients, uptake was reduced 12-fold in the presence or absence of Na+, and external choline+ induced internal alkalization of acidified basolateral vesicles. Accumulative [3H]choline+ uptakes by apical vesicles in the presence or absence of inside-negative charge gradients and Na+ were insignificant. We conclude that predominant choline+ uptake by type II pneumocytes occurs at the basolateral membrane by Na+-independent, electrogenic choline+ conductance. The presence of electroneutral choline+/H+ exchange is suggested. Copyright 1998 Academic Press.

A local renal renin-angiotensin system activation via renal uptake of prorenin and angiotensinogen in diabetic rats.

PubMed

Tojo, Akihiro; Kinugasa, Satoshi; Fujita, Toshiro; Wilcox, Christopher S

2016-01-01

The mechanism of activation of local renal renin-angiotensin system (RAS) has not been clarified in diabetes mellitus (DM). We hypothesized that the local renal RAS will be activated via increased glomerular filtration and tubular uptake of prorenin and angiotensinogen in diabetic kidney with microalbuminuria. Streptozotocin (STZ)-induced DM and control rats were injected with human prorenin and subsequently with human angiotensinogen. Human prorenin uptake was increased in podocytes, proximal tubules, macula densa, and cortical collecting ducts of DM rats where prorenin receptor (PRR) was expressed. Co-immunoprecipitation of kidney homogenates in DM rats revealed binding of human prorenin to the PRR and to megalin. The renal uptake of human angiotensinogen was increased in DM rats at the same nephron sites as prorenin. Angiotensin-converting enzyme was increased in podocytes, but decreased in the proximal tubules in DM rats, which may have contributed to unchanged renal levels of angiotensin despite increased angiotensinogen. The systolic blood pressure increased more after the injection of 20 μg of angiotensinogen in DM rats than in controls, accompanied by an increased uptake of human angiotensinogen in the vascular endothelium. In conclusion, endocytic uptake of prorenin and angiotensinogen in the kidney and vasculature in DM rats was contributed to increased tissue RAS and their pressor response to angiotensinogen.

Model simulation of NO3, N2O5 and ClNO2 at a rural site in Beijing during CAREBeijing-2006

NASA Astrophysics Data System (ADS)

Wang, Haichao; Lu, Keding; Tan, Zhaofeng; Sun, Kang; Li, Xin; Hu, Min; Shao, Min; Zeng, Limin; Zhu, Tong; Zhang, Yuanhang

2017-11-01

A chemical box model was used to study nitrate radical (NO3), dinitrogen pentoxide (N2O5) and nitryl chloride (ClNO2) in a rural site during the Campaign of Air Quality Research in Beijing 2006 (CAREBeijing-2006). The model was based on regional atmospheric chemistry mechanism version 2 (RACM2) with the heterogeneous uptake of N2O5 and the simplified chloride radical (Cl) chemistry mechanism. A high production rate of NO3 with a mean value of 0.8 ppbv/h and low mixing ratios of NO3 and N2O5 (peak values of 17 pptv and 480 pptv, respectively) existed in this site. Budget analysis showed that NO emission suppressed the NO3 chemistry at the surface layer, the reaction of NO3 with VOCs made a similar contribution to NO3 loss as N2O5 heterogeneous uptake. The NO3 chemistry was predominantly controlled by isoprene, and NO3 oxidation produced organic nitrate with a mean value of 0.06 ppbv/h during nighttime. The organic nitrate production initiated by NO3 was equal to that initiated by OH, implying the importance of nighttime chemistry for secondary organic aerosol (SOA) formation. We confirmed that the N2O5 heterogeneous reaction accounted for nighttime particle NO3- enhancement, with a large day to day variability, and made less of a contribution to NOx loss compared to that of OH reacting with NO2. Additionally, abundant ClNO2, up to 5.0 ppbv, was formed by N2O5 heterogeneous uptake. ClNO2 was sustained at a high level until noon in spite of the gradually increasing photolysis of ClNO2 after sunrise. Chlorine activation caused by N2O5 heterogeneous uptake increased primary ROx formation by 5% and accounted for 8% of the net ozone production enhancement in the morning.

Coherence between woody carbon uptake and net ecosystem productivity at five eddy-covariance sites

NASA Astrophysics Data System (ADS)

Babst, F.; Bouriaud, O.; Papale, D.; Gielen, B.; Janssens, I.; Nikinmaa, E.; Ibrom, A.; Wu, J.; Bernhofer, C.; Koestner, B.; Gruenwald, T.; Seufert, G.; Ciais, P.; Frank, D. C.

2013-12-01

Forest growth ranks amongst the most important processes that determine the carbon balance of terrestrial ecosystems. Quantifications of forest carbon cycling can be made e.g. using biometric and eddy-covariance (EC) techniques. Both offer different perspectives on carbon uptake and attempts to combine them have been inconsistent and variably successful in the past. This contributes to persistent uncertainties regarding carbon allocation in forest ecosystems and complicates precise vegetation model parameterization. Aiming to reconcile assessments of carbon cycling from biometric and EC techniques, we measured radial tree growth and wood density at five long-term EC stations across Europe. The resulting records were used to calculate annual carbon uptake during above-ground wood formation and compared to monthly and seasonal CO2-flux measurements. Efforts were made to identify i) the time periods when EC and tree-ring data correspond best in different parts of Europe and ii) the fraction of eddy-fluxes which is associated with changes in above-ground woody carbon stocks. Biometric measurements and net ecosystem productivity (NEP) proved largely compatible at seasonal time scales while relationships with gross primary productivity (GPP) were often weaker. Results suggest a partitioning of sequestered carbon mainly used for volume increase (January-June) and a combination of cell-wall thickening and storage (July-September). The inter-annual variability in above-ground woody carbon uptake was significantly linked with absolute productivity ranging between 69-366 g C m-2 y-1 at boreal and temperate sites, thereby accounting for 10-25% of GPP, 15-32% of TER, and 25-80% of NEP. These findings from sites representing the major European climate zones and tree species contribute to improved quantification of above-ground carbon allocation in forests. Furthermore, they refine knowledge on processes driving ecosystem productivity important for e.g. vegetation models and provide an enhanced framework for integrative studies linking tree-ring parameters with EC measurements.

Tianeptine: 5-HT uptake sites and 5-HT(1-7) receptors modulate memory formation in an autoshaping Pavlovian/instrumental task.

PubMed

Meneses, Alfredo

2002-05-01

Recent studies using invertebrate and mammal species have revealed that, endogenous serotonin (5-hydroxytryptamine, 5-HT) modulates cognitive processes, particularly learning and memory, though, at present, it is unclear the manner, where, and how long 5-HT systems are involved. Hence in this work, an attempt was made to study the effects of 5-HT endogenous on memory formation, using a 5-HT uptake facilitator (tianeptine) and, selective 5-HT(1-7) receptor antagonists to determine whether 5-HT uptake sites and which 5-HT receptors are involved, respectively. Results showed that post-training tianeptine injection enhanced memory consolidation in an autoshaping Pavlovian/instrumental learning task, which has been useful to detect changes on memory formation elicited by drugs or aging. On interaction experiments, ketanserin (5-HT(1D/2A/2C) antagonist) slightly enhanced tianeptine effects, while WAY 100635 (5-HT(1A) antagonist), SB-224289 (5-HT(1B) inverse agonist), SB-200646 (5-HT(2B/2C) antagonist), ondansetron (5-HT(3) antagonist), GR 127487 (5-HT(4) antagonist), Ro 04-6790 (5-HT(6) antagonist), DR 4004 (5-HT(7) antagonist), or fluoxetine (an inhibitor of 5-HT reuptake) blocked the facilitatory tianeptine effect. Notably, together tianeptine and Ro 04-6790 impaired learning consolidation. Moreover, 5-HT depletion completely reversed the tianeptine effect. Tianeptine also normalized an impaired memory elicited by scopolamine (an antimuscarinic) or dizocilpine (non-competitive glutamatergic antagonist), while partially reversed that induced by TFMPP (5-HT(1B/1D/2A-2C/7) agonist/antagonist). Finally, tianeptine-fluoxetine coadministration had no effect on learning consolidation; nevertheless, administration of an acetylcholinesterase inhibitor, phenserine, potentiated subeffective tianeptine or fluoxetine doses. Collectively, these data confirmed that endogenously 5-HT modulates, via uptake sites and 5-HT(1-7) receptors, memory consolidation, and are consistent with the emerging notion that 5-HT plays a key role on memory formation.

(68)Ga-DOTA-peptide: A novel molecular biomarker for nasopharyngeal carcinoma.

PubMed

Khor, Lih Kin; Loi, Hoi Yin; Sinha, Arvind Kumar; Tong, Kian Ti; Goh, Boon Cher; Loh, Kwok Seng; Lu, Suat-Jin

2016-04-01

Increased somatostatin receptor (SSTR) expression in patients with undifferentiated nasopharyngeal carcinoma (NPC) has been demonstrated with receptor autoradiography, (111) In-Octreotide scintigraphy, and (68) Ga-DOTA-TOC positron emission tomography (PET)/CT imaging. We sought to compare and correlate the uptake of fluorodeoxyglucose (FDG) and DOTA-NOC in undifferentiated NPC to ascertain the possible role of (68) Ga-DOTA-NOC PET/CT as a new imaging biomarker and to assess whether targeted peptide receptor radionuclide therapy is a feasible treatment option. After obtaining approval from our institutional review board, 4 patients with biopsy proven nonkeratinizing undifferentiated NPC who had just undergone routine staging/restaging (18) F-FDG PET/CT imaging were prospectively and consecutively recruited for (68) Ga-DOTA-NOC PET/CT imaging. Of these 4 patients, 3 were newly diagnosed with untreated NPC, whereas 1 patient was diagnosed with a case of recurrent NPC with previous treatment. These patients subsequently underwent (68) Ga-DOTA-NOC PET/CT within 10 days from the (18) F-FDG PET/CT to ensure lesion comparability. Tracer uptake in tumor lesions were assessed visually and semiquantitatively by measuring maximum standardized uptake values (SUVmax). There were 12 FDG-avid lesions of which 7 showed avid uptake of DOTA-NOC greater than liver uptake, whereas 5 showed low uptake of DOTA-NOC less than liver uptake. Subset analysis of the FDG-avid lesions at the primary and recurrent sites showed that all the FDG-avid primary tumors in the nasopharynx showed avid uptake of DOTA-NOC. On the contrary, the case of recurrent NPC showed avid FDG uptake but low DOTA-NOC uptake. Subset analysis of the suspicious FDG-avid cervical lymph nodes showed that 50% of them demonstrated avid DOTA-NOC uptake greater than liver uptake, whereas the remaining demonstrated low-grade DOTA-NOC uptake less than liver uptake. The 2 subcentimeter cervical lymph nodes that showed low-grade uptake of FDG lower than mediastinal blood pool activity were deemed to be reactive/inflammatory and showed low-grade uptake of DOTA-NOC. This study highlights the potential of (68) Ga-DOTA-peptide PET/CT as a new molecular biomarker for newly diagnosed undifferentiated NPC, and less so for recurrent NPC and metastatic nodes. This potentially opens up new diagnostic and therapeutic options in the management of undifferentiated NPC. © 2015 Wiley Periodicals, Inc.

Activity of a sodium-dependent vitamin C transporter (SVCT) in MDCK-MDR1 cells and mechanism of ascorbate uptake

PubMed Central

Luo, Shuanghui; Wang, Zhiying; Kansara, Viral; Pal, Dhananjay; Mitra, Ashim. K.

2008-01-01

The objective of this research was to functionally characterize sodium-dependent vitamin C transporter (SVCT) in MDCK-MDR1 cells and to study the effect of substituted benzene derivatives on the intracellular accumulation of ascorbic acid (AA). Mechanism of AA uptake and transport was delineated. Uptake of [14C]ascorbic acid ([14C]AA) was studied in the absence and presence of excess unlabelled AA, anion transporter inhibitors, and a series of mono- and di- substituted benzenes. Transepithelial transport of [14C]AA across polarized cell membrane has been studied for the first time. Role of cellular protein kinase mediated pathways on the regulation of AA uptake has been investigated. The cellular localizations of SVCTs were observed using confocal microscopy. Uptake of AA was found to be saturable with a Km of 83.2 μM and Vmax of 94.2 pmol/min/mg protein for SVCT1. The process was pH, sodium, temperature, and energy dependent. It was under the regulation of cellular protein kinase C (PKC) and Ca2+/CaM mediated pathways. [14C]AA uptake was significantly inhibited in the presence of excess unlabelled AA and a series of electron-withdrawing group i.e. halogen- and nitro- substituted benzene derivatives. AA appears to translocate across polarized cell membrane from apical to basal side (A−B) as well as basal to apical side (B−A) at a similar permeability. It appears that SVCT1 was mainly expressed on the apical side and SVCT2 may be located on both apical and basal sides. In conclusion, SVCT has been functionally characterized in MDCK-MDR1 cells. The interference of a series of electrophile substituted benzenes on the AA uptake process may be explained by their structural similarity. SVCT may be targeted to facilitate the delivery of drugs with low bioavailability by conjugating with AA and its structural analogs. MDCK-MDR1 cell line may be utilized as an in vitro model to study the permeability of AA conjugated prodrugs. PMID:18417304

Reserpine-induced reduction in norepinephrine transporter function requires catecholamine storage vesicles.

PubMed

Mandela, Prashant; Chandley, Michelle; Xu, Yao-Yu; Zhu, Meng-Yang; Ordway, Gregory A

2010-01-01

Treatment of rats with reserpine, an inhibitor of the vesicular monoamine transporter (VMAT), depletes norepinephrine (NE) and regulates NE transporter (NET) expression. The present study examined the molecular mechanisms involved in regulation of the NET by reserpine using cultured cells. Exposure of rat PC12 cells to reserpine for a period as short as 5min decreased [(3)H]NE uptake capacity, an effect characterized by a robust decrease in the V(max) of the transport of [(3)H]NE. As expected, reserpine did not displace the binding of [(3)H]nisoxetine from the NET in membrane homogenates. The potency of reserpine for reducing [(3)H]NE uptake was dramatically lower in SK-N-SH cells that have reduced storage capacity for catecholamines. Reserpine had no effect on [(3)H]NE uptake in HEK-293 cells transfected with the rat NET (293-hNET), cells that lack catecholamine storage vesicles. NET regulation by reserpine was independent of trafficking of the NET from the cell surface. Pre-exposure of cells to inhibitors of several intracellular signaling cascades known to regulate the NET, including Ca(2+)/Ca(2+)-calmodulin dependent kinase and protein kinases A, C and G, did not affect the ability of reserpine to reduce [(3)H]NE uptake. Treatment of PC12 cells with the catecholamine depleting agent, alpha-methyl-p-tyrosine, increased [(3)H]NE uptake and eliminated the inhibitory effects of reserpine on [(3)H]NE uptake. Reserpine non-competitively inhibits NET activity through a Ca(2+)-independent process that requires catecholamine storage vesicles, revealing a novel pharmacological method to modify NET function. Further characterization of the molecular nature of reserpine's action could lead to the development of alternative therapeutic strategies for treating disorders known to be benefitted by treatment with traditional competitive NET inhibitors. Copyright 2010 Elsevier Ltd. All rights reserved.

Interaction of human organic anion transporter 2 (OAT2) and sodium taurocholate cotransporting polypeptide (NTCP) with antineoplastic drugs.

PubMed

Marada, Venkata V V R; Flörl, Saskia; Kühne, Annett; Müller, Judith; Burckhardt, Gerhard; Hagos, Yohannes

2015-01-01

The ability of an antineoplastic drug to exert its cytostatic effect depends largely on the balance between its uptake into and extrusion from the cancer cells. ATP driven efflux transporter proteins drive the export of antineoplastic drugs and play a pivotal role in the development of chemoresistance. As regards uptake transporters, comparably less is known on their impact in drug action. In the current study, we characterized the interactions of two uptake transporter proteins, expressed mainly in the liver; the organic anion transporter 2 (OAT2, encoded by the SLC22A7 gene) and the sodium taurocholate cotransporting polypeptide (NTCP, encoded by the SLC10A1 gene), stably transfected in human embryonic kidney cells, with some antineoplastic agents that are routinely being used in cancer chemotherapy. Whereas NTCP did not show any strong interactions with the cytostatics tested, we observed a very strong inhibition of OAT2 mediated [(3)H] cGMP uptake in the presence of bendamustine, irinotecan and paclitaxel. The Ki values of OAT2 for bendamustine, irinotecan and paclitaxel were determined to be 43.3±4.33μM, 26.4±2.34μM and 10.4±0.45μM, respectively. Incubation of bendamustine with OAT2 expressing cells increased the caspase-3 activity, and this increase was inhibited by simultaneous incubation with bendamustine and probenecid, a well-known inhibitor of OATs, suggesting that bendamustine is a substrate of OAT2. A higher accumulation of irinotecan was observed in OAT2 expressing cells compared to control pcDNA cells by HPLC analysis of cell lysates. The accumulation was diminished in the presence of cGMP, the substrate we used to functionally characterize OAT2, suggesting specificity of this uptake and the fact that OAT2 mediates uptake of irinotecan. Copyright © 2014 Elsevier Ltd. All rights reserved.

K+ uptake in plant roots. The systems involved, their regulation and parallels in other organisms.

PubMed

Nieves-Cordones, Manuel; Alemán, Fernando; Martínez, Vicente; Rubio, Francisco

2014-05-15

Potassium (K(+)) is an essential macronutrient for plants. It is taken into the plant by the transport systems present in the plasma membranes of root epidermal and cortical cells. The identity of these systems and their regulation is beginning to be understood and the systems of K(+) transport in the model species Arabidopsis thaliana remain far better characterized than in any other plant species. Roots can activate different K(+) uptake systems to adapt to their environment, important to a sessile organism that needs to cope with a highly variable environment. The mechanisms of K(+) acquisition in the model species A. thaliana are the best characterized at the molecular level so far. According to the current model, non-selective channels are probably the main pathways for K(+) uptake at high concentrations (>10mM), while at intermediate concentrations (1mM), the inward rectifying channel AKT1 dominates K(+) uptake. Under lower concentrations of external K(+) (100μM), AKT1 channels, together with the high-affinity K(+) uptake system HAK5 contribute to K(+) acquisition, and at extremely low concentrations (<10μM) the only system capable of taking up K(+) is HAK5. Depending on the species the high-affinity system has been named HAK5 or HAK1, but in all cases it fulfills the same functions. The activation of these systems as a function of the K(+) availability is achieved by different mechanisms that include phosphorylation of AKT1 or induction of HAK5 transcription. Some of the characteristics of the systems for root K(+) uptake are shared by other organisms, whilst others are specific to plants. This indicates that some crucial properties of the ancestral of K(+) transport systems have been conserved through evolution while others have diverged among different kingdoms. Copyright © 2013 Elsevier GmbH. All rights reserved.

The binding sites for benztropines and dopamine in the dopamine transporter overlap

PubMed Central

Bisgaard, Heidi; Larsen, M. Andreas B.; Mazier, Sonia; Beuming, Thijs; Newman, Amy Hauck; Weinstein, Harel; Shi, Lei; Loland, Claus J.; Gether, Ulrik

2013-01-01

Analogues of benztropines (BZTs) are potent inhibitors of the dopamine transporter (DAT) but are less effective than cocaine as behavioral stimulants. As a result, there have been efforts to evaluate these compounds as leads for potential medication for cocaine addiction. Here we use computational modeling together with site-directed mutagenesis to characterize the binding site for BZTs in DAT. Docking into molecular models based on the structure of the bacterial homologue LeuT supported a BZT binding site that overlaps with the substrate binding pocket. In agreement, mutations of residues within the pocket, including Val1523.46* to Ala or Ile, Ser4228.60 to Ala and Asn1573.51 to Cys or Ala, resulted in decreased affinity for BZT and the analog JHW007, as assessed in [3H]dopamine uptake inhibition assays and/or [3H]CFT competition binding assay. A putative polar interaction of one of the phenyl ring fluorine substituents in JHW007 with Asn1573.51 was used as a criterion for determining likely binding poses and establish a structural context for the mutagenesis findings. The analysis positioned the other fluorine substituted phenyl ring of JHW007 in close proximity to Ala47910.51/Ala48010.52 in transmembrane segment (TM) 10. The lack of such an interaction for BZT led to a more tilted orientation, as compared to JHW007, bringing one of the phenyl rings even closer to Ala47910.51/Ala48010.52. Mutation of Ala47910.51 and Ala48010.52 to valines supported these predictions with a larger decrease in the affinity for BZT than for JHW007. Summarized, our data suggest that BZTs display a classical competitive binding mode with binding sites overlapping those of cocaine and dopamine. PMID:20816875

How Users Take Advantage of Different Forms of Interactivity on Online News Sites: Clicking, E-Mailing, and Commenting

ERIC Educational Resources Information Center

Boczkowski, Pablo J.; Mitchelstein, Eugenia

2012-01-01

This study examines the uptake of multiple interactive features on news sites. It looks at the thematic composition of the most clicked, most e-mailed, and most commented stories during periods of heightened and routine political activity. Results show that (a) during the former period, the most commented stories were more likely to be focused on…

Primary production export flux in Marguerite Bay (Antarctic Peninsula): Linking upper water-column production to sediment trap flux

NASA Astrophysics Data System (ADS)

Weston, Keith; Jickells, Timothy D.; Carson, Damien S.; Clarke, Andrew; Meredith, Michael P.; Brandon, Mark A.; Wallace, Margaret I.; Ussher, Simon J.; Hendry, Katharine R.

2013-05-01

A study was carried out to assess primary production and associated export flux in the coastal waters of the western Antarctic Peninsula at an oceanographic time-series site. New, i.e., exportable, primary production in the upper water-column was estimated in two ways; by nutrient deficit measurements, and by primary production rate measurements using separate 14C-labelled radioisotope and 15N-labelled stable isotope uptake incubations. The resulting average annual exportable primary production estimates at the time-series site from nutrient deficit and primary production rates were 13 and 16 mol C m-2, respectively. Regenerated primary production was measured using 15N-labelled ammonium and urea uptake, and was low throughout the sampling period. The exportable primary production measurements were compared with sediment trap flux measurements from 2 locations; the time-series site and at a site 40 km away in deeper water. Results showed ˜1% of the upper mixed layer exportable primary production was exported to traps at 200 m depth at the time-series site (total water column depth 520 m). The maximum particle flux rate to sediment traps at the deeper offshore site (total water column depth 820 m) was lower than the flux at the coastal time-series site. Flux of particulate organic carbon was similar throughout the spring-summer high flux period for both sites. Remineralisation of particulate organic matter predominantly occurred in the upper water-column (<200 m depth), with minimal remineralisation below 200 m, at both sites. This highly productive region on the Western Antarctic Peninsula is therefore best characterised as 'high recycling, low export'.

Contributions of system A subtypes to α-methylaminoisobutyric acid uptake by placental microvillous membranes of human and rat.

PubMed

Takahashi, Yu; Nishimura, Tomohiro; Maruyama, Tetsuo; Tomi, Masatoshi; Nakashima, Emi

2017-04-01

System A consists of three subtypes, sodium-coupled neutral amino acid transporter 1 (SNAT1), SNAT2, and SNAT4, which are all expressed in the placenta. The aim of this study was to evaluate the contributions of each of the three subtypes to total system A-mediated uptake in placental MVM of human and rat, using betaine and L-arginine as subtype-selective inhibitors of SNAT2 and SNAT4, respectively. Appropriate concentrations of betaine and L-arginine for subtype-selective inhibition in SNAT-overexpressing cells were identified. It was found that 10 mM betaine specifically and almost completely inhibited human and rat SNAT2-mediated [ 14 C]α-methylaminoisobutyric acid ([ 14 C]MeAIB) uptake, while 5 mM L-arginine specifically and completely inhibited [ 3 H]glycine uptake via human SNAT4, as well as [ 14 C]MeAIB uptake via rat SNAT4. In both human and rat placental MVM vesicles, sodium-dependent uptake of [ 14 C]MeAIB was almost completely inhibited by 20 mM unlabeled MeAIB. L-Arginine (5 mM) partly inhibited the uptake in humans, but hardly affected that in rats. Betaine (10 mM) partly inhibited the uptake in rats, but hardly affected it in humans. These results suggest that SNAT1 is most likely the major contributor to system A-mediated MeAIB uptake by human and rat MVM vesicles and that the remaining uptake is mainly mediated by SNAT4 in humans and SNAT2 in rats. Thus, inhibition studies using betaine and L-arginine are useful to characterize the molecular mechanisms of system A-mediated transport.

Translocation of myocardial GLUT-4 and increased glucose uptake through activation of AMPK by AICAR.

PubMed

Russell, R R; Bergeron, R; Shulman, G I; Young, L H

1999-08-01

Insulin increases glucose uptake through the translocation of GLUT-4 via a pathway mediated by phosphatidylinositol 3-kinase (PI3K). In contrast, myocardial glucose uptake during ischemia and hypoxia is stimulated by the translocation of GLUT-4 to the surface of cardiac myocytes through a PI3K-independent pathway that has not been characterized. AMP-activated protein kinase (AMPK) activity is also increased by myocardial ischemia, and we examined whether AMPK stimulates glucose uptake and GLUT-4 translocation. In isolated rat ventricular papillary muscles, 5-aminoimidazole-4-carboxyamide-1-beta-D-ribofuranoside (AICAR), an activator of AMPK, as well as cyanide-induced chemical hypoxia and insulin, increased 2-[(3)H]deoxyglucose uptake two- to threefold. Wortmannin, a PI3K inhibitor, did not affect either the AICAR- or the cyanide-stimulated increase in deoxyglucose uptake but eliminated the insulin-stimulated increase in deoxyglucose uptake. Immunofluorescence studies demonstrated translocation of GLUT-4 to the myocyte sarcolemma in response to stimulation with AICAR, cyanide, or insulin. Preincubation of papillary muscles with the kinase inhibitor iodotubercidin or adenine 9-beta-D-arabinofuranoside (araA), a precursor of araATP (a competitive inhibitor of AMPK), decreased AICAR- and cyanide-stimulated glucose uptake but did not affect basal or insulin-stimulated glucose uptake. In vivo infusion of AICAR caused myocardial AMPK activation and GLUT-4 translocation in the rat. We conclude that AMPK activation increases cardiac muscle glucose uptake through translocation of GLUT-4 via a pathway that is independent of PI3K. These findings suggest that AMPK activation may be important in ischemia-induced translocation of GLUT-4 in the heart.