A Thermodynamically-consistent FBA-based Approach to Biogeochemical Reaction Modeling

NASA Astrophysics Data System (ADS)

Shapiro, B.; Jin, Q.

2015-12-01

Microbial rates are critical to understanding biogeochemical processes in natural environments. Recently, flux balance analysis (FBA) has been applied to predict microbial rates in aquifers and other settings. FBA is a genome-scale constraint-based modeling approach that computes metabolic rates and other phenotypes of microorganisms. This approach requires a prior knowledge of substrate uptake rates, which is not available for most natural microbes. Here we propose to constrain substrate uptake rates on the basis of microbial kinetics. Specifically, we calculate rates of respiration (and fermentation) using a revised Monod equation; this equation accounts for both the kinetics and thermodynamics of microbial catabolism. Substrate uptake rates are then computed from the rates of respiration, and applied to FBA to predict rates of microbial growth. We implemented this method by linking two software tools, PHREEQC and COBRA Toolbox. We applied this method to acetotrophic methanogenesis by Methanosarcina barkeri, and compared the simulation results to previous laboratory observations. The new method constrains acetate uptake by accounting for the kinetics and thermodynamics of methanogenesis, and predicted well the observations of previous experiments. In comparison, traditional methods of dynamic-FBA constrain acetate uptake on the basis of enzyme kinetics, and failed to reproduce the experimental results. These results show that microbial rate laws may provide a better constraint than enzyme kinetics for applying FBA to biogeochemical reaction modeling.

Mechanisms of vitamin K transport and metabolism in Swiss 3T3 mouse fibroblasts

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

Canfield, L.M.; Townsend, A.F.; Hibbs, D.B.

Transport of vitamin K into isolated fibroblasts was followed using /sup 3/H vitamin K/sub 1/. The initial rate is saturable by 5 min. at 25..mu..M vitamin K with a Km(app) of 10..mu..M and V/sub max/ of 50 pmols/min/10/sup 6/ cells. Kinetics of uptake are biphasic with a second slower rate ensuing after 10 minutes. Insensitivity of the initial rate of uptake to FCCP or ouabain indicates an ATP-independent transport mechanism. Specificity of transport is shown by competition of uptake of /sup 3/H vitamin K by unlabelled vitamin and strong (>90%) inhibition of the initial rate by equimolar concentrations of themore » vitamin K analog, Chloro-K. In addition, following uptake, both vitamins K/sub 1/ and K/sub 2/ are metabolized to their respective epoxides. Vitamin K/sub 1/ epoxide is also transported into fibroblasts and metabolized to the parent quinone in a Warfarin-sensitive reaction. Following alkaline hydrolysis of isolated intracellular protein, the vitamin K-dependent amino acid, gamma carboxyglutamic acid (gla) was detected. It is concluded that vitamin K is specifically transported into fibroblasts and metabolized via the classical pathway described in liver with the concomitant production of vitamin K-dependent proteins.« less

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

Šefl, Martin, E-mail: martin.sefl@gmail.com; Kyriakou, Ioanna; Emfietzoglou, Dimitris, E-mail: demfietz@cc.uoi.gr

Purpose: To study theoretically the impact on cell survival of the radionuclide uptake rate inside tumor cells for a single administration of a radiopharmaceutical. Methods: The instantaneous-uptake model of O’Donoghue [“The impact of tumor cell proliferation in radioimmunotherapy,” Cancer 73, 974–980 (1994)] for a proliferating cell population irradiated by an exponentially decreasing dose-rate is here extended to allow for the monoexponential uptake of the radiopharmaceutical by the targeted cells. The time derivative of the survival curve is studied in detail deducing an expression for the minimum of the surviving fraction and the biologically effective dose (BED). Results: Surviving fractions aremore » calculated over a parameter range that is clinically relevant and broad enough to establish general trends. Specifically, results are presented for the therapy radionuclides Y-90, I-131, and P-32, assuming uptake half-times 1–24 h, extrapolated initial dose-rates 0.5–1 Gy h{sup −1}, and a biological clearance half-life of seven days. Representative radiobiological parameters for radiosensitive and rapidly proliferating tumor cells are used, with cell doubling time equal to 2 days and α-coefficient equal to 0.3 and 0.5 Gy{sup −1}. It is shown that neglecting the uptake phase of the radiopharmaceutical (i.e., assuming instantaneous-uptake) results in a sizeable over-estimation of cell-kill (i.e., under-estimation of cell survival) even for uptake half-times of only a few hours. The differences between the exponential-uptake model and the instantaneous-uptake model become larger for high peak dose-rates, slow uptakes, and (slightly) for long-lived radionuclides. Moreover, the sensitivity of the survival curve on the uptake model was found to be higher for the tumor cells with the larger α-coefficient. Conclusions: The exponential-uptake rate of the radiopharmaceutical inside targeted cells appears to have a considerable effect on the survival of a proliferating cell population and might need to be considered in radiobiological models of tumor cell-kill in radionuclide therapy.« less

Increase in nitrate uptake by soybean plants during interruption of the dark period with low intensity light

NASA Technical Reports Server (NTRS)

Raper, C. D. Jr; Vessey, J. K.; Henry, L. T.

1991-01-01

Diurnal patterns of net NO3- uptake by nonnodulated soybean [Glycine max (L.) Merr. cv. Ransom] plants growing in flowing hydroponic culture at 26 and 16 degrees C root temperatures were measured at hourly intervals during alternate days of a 12-day growth period. Ion chromatography was used to determine removal of NO3- from the culture solution. Day and night periods of 9 and 15 h were used during growth. The night period included two 6-h dark periods and an intervening 3-h period of night interruption by incandescent lamps to effect a long-day photoperiod and repress floral initiation. At both root temperatures, the average specific rates of NO3- uptake were twice as great during the night interruption period as during the day period; they were greater during the day period than during the dark periods; and they were greater during the dark period immediately following the day period than during the later dark period that followed the night interruption. While these average patterns were repetitious among days, measured rates of uptake varied hourly and included intervals of net efflux scattered through the day period and more frequently through the 2 dark periods. Root temperature did not affect the average daily specific rates of uptake or the qualitative relationships among day, dark and night interruption periods of the diurnal cycle.

Lesion-induced plasticity of high affinity choline uptake in the developing rat fascia dentata.

PubMed

Nadler, J V; Shelton, D L; Cotman, C W

1979-03-23

After removal of the perforant path input to the rat fascia dentata at the age of 11 days, cholinergic septohippocampal fibers invade the denervated area. We have examined the effect of this lesion on hemicholinium-sensitive, high affinity choline uptake and its coupling to acetylcholine synthesis, specific properties of the septohippocampal input. Removal of the ipsilateral perforant path fibers increased the velocity of high affinity choline uptake by dentate particulate preparations, usually within 1 day. Studies conducted 5--104 days after operation showed a consistent 50--65% elevation in the molecular (denervated) layer. In contrast, the choline uptake rate in the granular layer eventually decreased slightly. Calculation of choline uptake rates independently of protein (per whole region) revealed that fasciae dentatae from operated and control sides accumulated choline at approximately equal rates, but on the operated side a greater percentage was transported by structures from the molecular layer and a lesser percentage by those from the granular layer. The rate of acetylcholine synthesis from exogenous choline increased to the same extent as high affinity choline uptake from 3 days after operation onwards. The changes in high affinity choline uptake and acetylcholine synthesis coincided spatially and temporally with the reactive growth of septohippocampal fibers. Our results support the view that a perforant path lesion during development permanently alters the distribution of functional septohippocampal boutons in the fascia dentata. Acetylcholine synthesis is regulated to the same extent by high affinity choline uptake in the anomalous boutons as in normally located boutons.

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

Accelerated Analyte Uptake on Single Beads in Microliter-scale Batch Separations using Acoustic Streaming: Plutonium Uptake by Anion Exchange for Analysis by Mass Spectrometry

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

Paxton, Walter F.; O'Hara, Matthew J.; Peper, Shane M.

2008-06-01

The use of acoustic streaming as a non-contact mixing platform to accelerate mass transport-limited diffusion processes in small volume heterogeneous reactions has been investigated. Single bead anion exchange of plutonium at nanomolar and sub-picomolar concentrations in 20 microliter liquid volumes was used to demonstrate the effect of acoustic mixing. Pu uptake rates on individual ~760 micrometer diameter AG 1x4 anion exchange resin beads were determined using acoustic mixing and compared with Pu uptake rates achieved by static diffusion alone. An 82 MHz surface acoustic wave (SAW) device was placed in contact with the underside of a 384-well microplate containing flat-bottomedmore » semiconical wells. Acoustic energy was coupled into the solution in the well, inducing acoustic streaming. Pu uptake rates were determined by the plutonium remaining in solution after specific elapsed time intervals, using liquid scintillation counting (LSC) for nanomolar concentrations and thermal ionization mass spectrometry (TIMS) analysis for the sub-picomolar concentration experiments. It was found that this small batch uptake reaction could be accelerated by a factor of about five-fold or more, depending on the acoustic power applied.« less

Mechanisms of Hg(II) uptake and methylation in methylating bacteria

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

Morel, Francois M. M.

2016-10-14

The goal of this project was to understand the critical factors which control the availability and transport of Hg(II) into cells, a first step in the production of the neurotoxin, methylmercury. Specifically, this research focused on understanding the mechanism of bacterial mercury uptake and how mercury speciation affects the specificity and kinetics of mercury transport. Our research has shown that Hg(II) uptake in three different iron and sulfate-reducing proteobacteria occurs by the following mechanism (1) : Hg(II) uptake is an active transport process requiring energy, (2) it is dependent upon the structure of the Hg binding ligand, and (3) itmore » is mediated by a heavy metal transporter such as one which transports the essential metal, Zn(II). In order to determine whether this mechanism extends to more diverse phylogenetic groups, we have begun examining Hg(II) uptake and bioavailability in two representative Hg methylating strains within the Firmicutes. These organisms have remarkably different membrane structures distinct from the Proteobacteria. Our results show low uptake rates in these two species of Firmicutes relative to the previously characterized Proteobacteria. This may explain the low methylation rates and yields observed in these organisms. Most surprisingly, however, these organisms appear to take up Hg(II) passively, as the addition of a protonophore failed to reduce Hg(II) uptake in these organisms. This is quite different to what has been observed previously for the Proteobacteria and suggests a different mechanism for Hg(II) uptake in the Firmicutes. We are continuing to understand and describe Hg(II) uptake in these organisms. A manuscript is expected to be submitted on this research in June 2016.« less

Relative contributions of copper oxide nanoparticles and dissolved copper to Cu uptake kinetics of Gulf killifish (Fundulus grandis) embryos

USGS Publications Warehouse

Jiang, Chuanjia; Castellon, Benjamin T.; Matson, Cole W.; Aiken, George R.; Hsu-Kim, Heileen

2017-01-01

The toxicity of soluble metal-based nanomaterials may be due to the uptake of metals in both dissolved and nanoparticulate forms, but the relative contributions of these different forms to overall metal uptake rates under environmental conditions are not quantitatively defined. Here, we investigated the linkage between the dissolution rates of copper(II) oxide (CuO) nanoparticles (NPs) and their bioavailability to Gulf killifish (Fundulus grandis) embryos, with the aim of quantitatively delineating the relative contributions of nanoparticulate and dissolved species for Cu uptake. Gulf killifish embryos were exposed to dissolved Cu and CuO NP mixtures comprising a range of pH values (6.3–7.5) and three types of natural organic matter (NOM) isolates at various concentrations (0.1–10 mg-C L–1), resulting in a wide range of CuO NP dissolution rates that subsequently influenced Cu uptake. First-order dissolution rate constants of CuO NPs increased with increasing NOM concentration and for NOM isolates with higher aromaticity, as indicated by specific ultraviolet absorbance (SUVA), while Cu uptake rate constants of both dissolved Cu and CuO NP decreased with NOM concentration and aromaticity. As a result, the relative contribution of dissolved Cu and nanoparticulate CuO species for the overall Cu uptake rate was insensitive to NOM type or concentration but largely determined by the percentage of CuO that dissolved. These findings highlight SUVA and aromaticity as key NOM properties affecting the dissolution kinetics and bioavailability of soluble metal-based nanomaterials in organic-rich waters. These properties could be used in the incorporation of dissolution kinetics into predictive models for environmental risks of nanomaterials.

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

Platelet-derived-growth-factor-stimulated heterogeneous polyphosphoinositide metabolism and phosphate uptake in C3H fibroblasts.

PubMed Central

Holmsen, H; Male, R; Rongved, S; Langeland, N; Lillehaug, J

1989-01-01

Pig platelet-derived growth factor (PDGF) increased the rate of [32P]Pi uptake by murine fibroblasts, resulting in a 3-9-fold elevation of the specific radioactivity of ATP, PtdInsP, PtdInsP2, PtdIns and phosphatidic acid. The specific radioactivity was 10-60-fold higher in ATP than in the four phospholipids. These substances are therefore not in metabolic equilibrium, which complicates determination of inositol phospholipid turnover. PMID:2548480

Ceruloplasmin ferroxidase activity stimulates cellular iron uptake by a trivalent cation-specific transport mechanism

NASA Technical Reports Server (NTRS)

Attieh, Z. K.; Mukhopadhyay, C. K.; Seshadri, V.; Tripoulas, N. A.; Fox, P. L.

1999-01-01

The balance required to maintain appropriate cellular and tissue iron levels has led to the evolution of multiple mechanisms to precisely regulate iron uptake from transferrin and low molecular weight iron chelates. A role for ceruloplasmin (Cp) in vertebrate iron metabolism is suggested by its potent ferroxidase activity catalyzing conversion of Fe2+ to Fe3+, by identification of yeast copper oxidases homologous to Cp that facilitate high affinity iron uptake, and by studies of "aceruloplasminemic" patients who have extensive iron deposits in multiple tissues. We have recently shown that Cp increases iron uptake by cultured HepG2 cells. In this report, we investigated the mechanism by which Cp stimulates cellular iron uptake. Cp stimulated the rate of non-transferrin 55Fe uptake by iron-deficient K562 cells by 2-3-fold, using a transferrin receptor-independent pathway. Induction of Cp-stimulated iron uptake by iron deficiency was blocked by actinomycin D and cycloheximide, consistent with a transcriptionally induced or regulated transporter. Cp-stimulated iron uptake was completely blocked by unlabeled Fe3+ and by other trivalent cations including Al3+, Ga3+, and Cr3+, but not by divalent cations. These results indicate that Cp utilizes a trivalent cation-specific transporter. Cp ferroxidase activity was required for iron uptake as shown by the ineffectiveness of two ferroxidase-deficient Cp preparations, copper-deficient Cp and thiomolybdate-treated Cp. We propose a model in which iron reduction and subsequent re-oxidation by Cp are essential for an iron uptake pathway with high ion specificity.

The effect of folate status on the uptake of physiologically relevant compounds by Caco-2 cells.

PubMed

Tavares, Sandra; Sousa, Joana; Gonçalves, Pedro; Araújo, João R; Martel, Fátima

2010-08-25

The aim of this work was to investigate the effect of folate status on the uptake of several physiologically relevant substances by Caco-2 cells. For this, Caco-2 cells cultured in high-folate conditions (HF) and low-folate conditions (LF) were compared. Growth rates of HF and LF Caco-2 cells were similar. However, proliferation rate of LF cells was greater than that of HF cells during the first 2days of culture and slightly smaller thereafter, viability of LF cells was greater than that of HF cells, and apoptosis index was similar in both cell cultures. We verified that in LF cells, comparatively to HF cells: (1) uptake of [3H]folic acid is upregulated, via an increase in the Vmax of uptake; (2) uptake of [3H]deoxy-glucose, [3H]O-methyl-glucose and [3H]1-methyl-4-phenylpyridinium (MPP+) is downregulated, via a decrease in the Vmax of uptake; additionally, a reduction in Km was observed for [3H]O-methyl-glucose; (3) uptake of [3H]5-hydroxytryptamine and [14C]butyrate is not changed; and (4) the steady-state mRNA levels of the folic acid transporters RFC (reduced folate carrier), PCFT (proton-coupled folate transporter) and FRalpha (folate receptor alpha), of the organic cation transporter OCT1 (organic cation transporter type 1), of the glucose transporter GLUT2 (facilitative glucose transporter type 2) and of the butyrate transporter MCT1 (monocarboxylate transporter type 1) were decreased. In conclusion, folate deficiency produces substrate-specific changes in the uptake of bioactive compounds by Caco-2 cells. Moreover, these changes are associated with alterations in the mRNA levels of specific transporters for these compounds. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Nitrogen uptake by the shoots of smooth cordgrass Spartina alterniflora

USGS Publications Warehouse

Mozdzer, T.J.; Kirwan, M.; McGlathery, K.J.; Zieman, J.C.

2011-01-01

The smooth cordgrass Spartina alterniflora is the foundation species in intertidal salt marshes of the North American Atlantic coast. Depending on its elevation within the marsh, S. alterniflora may be submerged for several hours per day. Previous ecosystem-level studies have demonstrated that S. alterniflora marshes are a net sink for nitrogen (N), and that removal of N from flooding tidal water can provide enough N to support the aboveground biomass. However, studies have not specifically investigated whether S. alterniflora plants assimilate nutrients through their aboveground tissue. We determined in situ foliar and stem N uptake kinetics for 15NH4, 15NO3, and 15N-glycine by artificially flooding plants in a mid-Atlantic salt marsh. To determine the ecological importance of shoot uptake, a model was created to estimate the time of inundation of S. alterniflora in 20 cm height intervals during the growing season. Estimates of inundation time, shoot mass, N uptake rates, and N availability from long-term data sets were used to model seasonal shoot N uptake. Rates of aboveground N uptake rates (leaves + stems) were ranked as follows: NH4+ > glycine > NO3–. Our model suggests that shoot N uptake may satisfy up to 15% of the growing season N demand in mid-Atlantic salt marshes, with variation depending on plant elevation and water column N availability. However, in eutrophic estuaries, our model indicates the potential of the plant canopy as a nutrient filter, with shoot uptake contributing 66 to 100% of plant N demand.

Kinetics of phosphate uptake, growth, and accumulation of cyclic diphosphoglycerate in a phosphate-limited continuous culture of Methanobacterium thermoautotrophicum.

PubMed Central

Krueger, R D; Harper, S H; Campbell, J W; Fahrney, D E

1986-01-01

The archaebacterium Methanobacterium thermoautotrophicum was grown in continuous culture at 65 degrees C in a phosphate-limited medium at specific growth rates from 0.06 to 0.28 h-1 (maximum growth rate [mu max] = 0.36 h-1). Cyclic-2,3-diphosphoglycerate (cyclic DPG) levels ranged from 2 to 20 mM in Pi-limited cells, compared with about 30 mM in batch-grown cells. The Monod constant for Pi-limited growth was 5 nM. Pi uptake rates were determined by following the disappearance of 32Pi from the medium. Interrupting the H2 supply stopped the uptake of Pi and the release of organic phosphates. Little or no efflux of Pi occurred in the presence or absence of H2. Pi uptake of cells adapted to nanomolar Pi concentrations could be accounted for by the operation of one uptake system with an apparent Km of about 25 nM and a Vmax of 58 nmol of Pi per min per g (dry weight). Uptake curves at 30 microM Pi or above were biphasic due to a sevenfold decrease in Vmax after an initial phase of rapid movement of Pi into the cell. Under these conditions the growth rate slowed to zero and the cyclic DPG pool expanded before growth resumed. Thus, three properties of M. thermoautotrophicum make it well adapted to live in a low-P environment: the presence of a low-Km, high-Vmax uptake system for Pi; the ability to accumulate cyclic DPG rapidly; and a growth strategy in which accumulation of Pi and cyclic DPG takes precedence over a shift-up in growth rate when excess Pi becomes available. PMID:3722128

Kinetics of phosphate uptake, growth, and accumulation of cyclic diphosphoglycerate in a phosphate-limited continuous culture of Methanobacterium thermoautotrophicum.

PubMed

Krueger, R D; Harper, S H; Campbell, J W; Fahrney, D E

1986-07-01

The archaebacterium Methanobacterium thermoautotrophicum was grown in continuous culture at 65 degrees C in a phosphate-limited medium at specific growth rates from 0.06 to 0.28 h-1 (maximum growth rate [mu max] = 0.36 h-1). Cyclic-2,3-diphosphoglycerate (cyclic DPG) levels ranged from 2 to 20 mM in Pi-limited cells, compared with about 30 mM in batch-grown cells. The Monod constant for Pi-limited growth was 5 nM. Pi uptake rates were determined by following the disappearance of 32Pi from the medium. Interrupting the H2 supply stopped the uptake of Pi and the release of organic phosphates. Little or no efflux of Pi occurred in the presence or absence of H2. Pi uptake of cells adapted to nanomolar Pi concentrations could be accounted for by the operation of one uptake system with an apparent Km of about 25 nM and a Vmax of 58 nmol of Pi per min per g (dry weight). Uptake curves at 30 microM Pi or above were biphasic due to a sevenfold decrease in Vmax after an initial phase of rapid movement of Pi into the cell. Under these conditions the growth rate slowed to zero and the cyclic DPG pool expanded before growth resumed. Thus, three properties of M. thermoautotrophicum make it well adapted to live in a low-P environment: the presence of a low-Km, high-Vmax uptake system for Pi; the ability to accumulate cyclic DPG rapidly; and a growth strategy in which accumulation of Pi and cyclic DPG takes precedence over a shift-up in growth rate when excess Pi becomes available.

Carbon allocation and nitrogen acquisition in a developing Populus deltoides plantation

Treesearch

Mark D. Coleman; Christel C. Kern

2004-01-01

We established Populus deltoides Bartr. stands differing in nitrogen (N) availability and tested if: (1) N-induced carbon (C) allocation could be explained by developmental allocation controls; and (2) N uptake per unit root mass, i.e., specific N-uptake rate, increased with N availability. Closely spaced (1 x 1 m) stands were treated with 50, 100...

Role of Pseudomonas putida tol-oprL Gene Products in Uptake of Solutes through the Cytoplasmic Membrane

PubMed Central

Llamas, María A.; Rodríguez-Herva, José J.; Hancock, Robert E. W.; Bitter, Wilbert; Tommassen, Jan; Ramos, Juan L.

2003-01-01

Proteins of the Tol-Pal (Tol-OprL) system play a key role in the maintenance of outer membrane integrity and cell morphology in gram-negative bacteria. Here we describe an additional role for this system in the transport of various carbon sources across the cytoplasmic membrane. Growth of Pseudomonas putida tol-oprL mutant strains in minimal medium with glycerol, fructose, or arginine was impaired, and the growth rate with succinate, proline, or sucrose as the carbon source was lower than the growth rate of the parental strain. Assays with radiolabeled substrates revealed that the rates of uptake of these compounds by mutant cells were lower than the rates of uptake by the wild-type strain. The pattern and amount of outer membrane protein in the P. putida tol-oprL mutants were not changed, suggesting that the transport defect was not in the outer membrane. Consistently, the uptake of radiolabeled glucose and glycerol in spheroplasts was defective in the P. putida tol-oprL mutant strains, suggesting that there was a defect at the cytoplasmic membrane level. Generation of a proton motive force appeared to be unaffected in these mutants. To rule out the possibility that the uptake defect was due to a lack of specific transporter proteins, the PutP symporter was overproduced, but this overproduction did not enhance proline uptake in the tol-oprL mutants. These results suggest that the Tol-OprL system is necessary for appropriate functioning of certain uptake systems at the level of the cytoplasmic membrane. PMID:12896989

Effects of root-zone acidity on utilization of nitrate and ammonium in tobacco plants

NASA Technical Reports Server (NTRS)

Henry, L. T.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

1989-01-01

Tobacco (Nicotiana tabacum L., cv. 'Coker 319') plants were grown for 28 days in flowing nutrient culture containing either 1.0 mM NO3- or 1.0 mM NH4+ as the nitrogen source in a complete nutrient solution. Acidities of the solutions were controlled at pH 6.0 or 4.0 for each nitrogen source. Plants were sampled at intervals of 6 to 8 days for determination of dry matter and nitrogen accumulation. Specific rates of NO3- or NH4+ uptake (rate of uptake per unit root mass) were calculated from these data. Net photosynthetic rates per unit leaf area were measured on attached leaves by infrared gas analysis. When NO3- [correction of NO-] was the sole nitrogen source, root growth and nitrogen uptake rate were unaffected by pH of the solution, and photosynthetic activity of leaves and accumulation of dry matter and nitrogen in the whole plant were similar. When NH4+ was the nitrogen source, photosynthetic rate of leaves and accumulation of dry matter and nitrogen in the whole plant were not statistically different from NO3(-) -fed plants when acidity of the solution was controlled at pH 6.0. When acidity for NH4(+) -fed plants was increased to pH 4.0, however, specific rate of NH4+ uptake decreased by about 50% within the first 6 days of treatment. The effect of acidity on root function was associated with a decreased rate of accumulation of nitrogen in shoots that was accompanied by a rapid cessation of leaf development between days 6 and 13. The decline in leaf growth rate of NH4(+) -fed plants at pH 4.0 was followed by reductions in photosynthetic rate per unit leaf area. These responses of NH4(+) -fed plants to increased root-zone acidity are characteristic of the sequence of responses that occur during onset of nitrogen stress.

Fermentation process using specific oxygen uptake rates as a process control

DOEpatents

Van Hoek, Pim; Aristidou, Aristos; Rush, Brian J.

2016-08-30

Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

Fermentation process using specific oxygen uptake rates as a process control

DOEpatents

Van Hoek, Pim [Minnetonka, MN; Aristidou, Aristos [Maple Grove, MN; Rush, Brian [Minneapolis, MN

2011-05-10

Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

Fermentation process using specific oxygen uptake rates as a process control

DOEpatents

Hoek, Van; Pim, Aristidou [Minnetonka, MN; Aristos, Rush [Maple Grove, MN; Brian, [Minneapolis, MN

2007-06-19

Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

Fermentation process using specific oxygen uptake rates as a process control

DOEpatents

Van Hoek, Pim; Aristidou, Aristos; Rush, Brian

2014-09-09

Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

Specific bile acids inhibit hepatic fatty acid uptake

PubMed Central

Nie, Biao; Park, Hyo Min; Kazantzis, Melissa; Lin, Min; Henkin, Amy; Ng, Stephanie; Song, Sujin; Chen, Yuli; Tran, Heather; Lai, Robin; Her, Chris; Maher, Jacquelyn J.; Forman, Barry M.; Stahl, Andreas

2012-01-01

Bile acids are known to play important roles as detergents in the absorption of hydrophobic nutrients and as signaling molecules in the regulation of metabolism. Here we tested the novel hypothesis that naturally occurring bile acids interfere with protein-mediated hepatic long chain free fatty acid (LCFA) uptake. To this end stable cell lines expressing fatty acid transporters as well as primary hepatocytes from mouse and human livers were incubated with primary and secondary bile acids to determine their effects on LCFA uptake rates. We identified ursodeoxycholic acid (UDCA) and deoxycholic acid (DCA) as the two most potent inhibitors of the liver-specific fatty acid transport protein 5 (FATP5). Both UDCA and DCA were able to inhibit LCFA uptake by primary hepatocytes in a FATP5-dependent manner. Subsequently, mice were treated with these secondary bile acids in vivo to assess their ability to inhibit diet-induced hepatic triglyceride accumulation. Administration of DCA in vivo via injection or as part of a high-fat diet significantly inhibited hepatic fatty acid uptake and reduced liver triglycerides by more than 50%. In summary, the data demonstrate a novel role for specific bile acids, and the secondary bile acid DCA in particular, in the regulation of hepatic LCFA uptake. The results illuminate a previously unappreciated means by which specific bile acids, such as UDCA and DCA, can impact hepatic triglyceride metabolism and may lead to novel approaches to combat obesity-associated fatty liver disease. PMID:22531947

Herbivores, tidal elevation, and species richness simultaneously mediate nitrate uptake by seaweed assemblages.

PubMed

Bracken, Matthew E S; Jones, Emily; Williams, Susan L

2011-05-01

In order for research into the consequences of biodiversity changes to be more applicable to real-world ecosystems, experiments must be conducted in the field, where a variety of factors other than diversity can affect the rates of key biogeochemical and physiological processes. Here, we experimentally evaluate the effects of two factors known to affect the diversity and composition of intertidal seaweed assemblages--tidal elevation and herbivory--on nitrate uptake by those assemblages. Based on surveys of community composition at the end of a 1.5-year press experiment, we found that both tide height and herbivores affected seaweed community structure. Not surprisingly, seaweed species richness was greater at lower tidal elevations. Herbivores did not affect richness, but they altered the types of species that were present; seaweed species characterized by higher rates of nitrate uptake were more abundant in herbivore-removal plots. Both tide height and herbivores affected nitrate uptake by seaweed assemblages. Individual seaweed species, as well as entire seaweed assemblages, living higher on the shore had greater rates of biomass-specific nitrate uptake, particularly at high ambient nitrate concentrations. Grazed seaweed assemblages exhibited reduced nitrate uptake, but only at low nitrate concentrations. We evaluated the effect of seaweed richness on nitrate uptake, both alone and after accounting for effects of tidal elevation and herbivores. When only richness was considered, we found no effect on uptake. However, when simultaneous effects of richness, tide height, and herbivores on uptake were evaluated, we found that all three had relatively large and comparable effects on nitrate uptake coefficients and that there was a negative relationship between seaweed richness and nitrate uptake. Particularly because effects of richness on uptake were not apparent unless the effects of tide height and herbivory were also considered, these results highlight the importance of considering the effects of environmental context when evaluating the consequences of biodiversity change in more realistic systems.

Market uptake of new antiviral drugs for the treatment of hepatitis C.

PubMed

Lettmeier, Beate; Mühlberger, Nikolai; Schwarzer, Ruth; Sroczynski, Gaby; Wright, Davene; Zeuzem, Stefan; Siebert, Uwe

2008-10-01

Peginterferon plus ribavirin is the state-of-the-art antiviral therapy for prevention of serious complications of hepatitis C. Our aim was to compare market uptake of and access to these drugs across Europe. We collected launch and sales data for peginterferons for 21 countries in the WHO European region and compared country-specific sales rates. Additionally, we converted sales figures into patient numbers and related those to country-specific hepatitis C prevalence, taking into account genotype distribution, patient characteristics and practice patterns. Peginterferon sales rates differed considerably across countries. The earliest, most rapid and highest adoption rates were in EU founder states, followed by EU members that joined after foundation, and EU non-member states. Most new member states showed a marked increase in sales. By the end of 2005, approximately 308,000 patients had been treated with peginterferons in the 21 countries evaluated. The number of patients ever treated ranged from 16% of prevalent cases in France to less than 1% of cases in Romania, Poland, Greece and Russia. Peginterferon market uptake and access differed considerably across Europe, suggesting unequal access to optimised therapy. Besides budget restrictions, national surveillance and treatment policies should be considered as reasons for market access variation.

Nitrogen uptake by the shoots of smooth cordgrass Spartina alterniflora

USGS Publications Warehouse

Mozdzer, T.J.; Kirwan, M.; McGlathery, K.J.; Zieman, J.C.

2011-01-01

The smooth cordgrass Spartina alterniflora is the foundation species in intertidal salt marshes of the North American Atlantic coast. Depending on its elevation within the marsh, S. alterniflora may be submerged for several hours per day. Previous ecosystem-level studies have demonstrated that S. alterniflora marshes are a net sink for nitrogen (N), and that removal of N from flooding tidal water can provide enough N to support the aboveground biomass. However, studies have not specifically investigated whether S. alterniflora plants assimilate nutrients through their aboveground tissue. We determined in situ foliar and stem N uptake kinetics for 15NH4, 15NO3, and 15N-glycine by artificially flooding plants in a mid-Atlantic salt marsh. To determine the ecological importance of shoot uptake, a model was created to estimate the time of inundation of S. alterniflora in 20 cm height intervals during the growing season. Estimates of inundation time, shoot mass, N uptake rates, and N availability from long-term data sets were used to model seasonal shoot N uptake. Rates of aboveground N uptake rates (leaves + stems) were ranked as follows: NH4 + > glycine > NO3 -. Our model suggests that shoot N uptake may satisfy up to 15% of the growing season N demand in mid-Atlantic salt marshes, with variation depending on plant elevation and water column N availability. However, in eutrophic estuaries, our model indicates the potential of the plant canopy as a nutrient filter, with shoot uptake contributing 66 to 100% of plant N demand. ?? 2011 Inter-Research.

Uptake and patient outcomes of laparoscopic colon and rectal cancer surgery in a publicly funded system and following financial incentives.

PubMed

Simunovic, Marko; Baxter, Nancy N; Sutradhar, Rinku; Liu, Ning; Cadeddu, Margherita; Urbach, David

2013-11-01

To assess patterns of uptake and outcomes of laparoscopic colon and rectal cancer surgery in Ontario, and the potential influence of surgical fee incentives instituted on October 1, 2005. We used Ontario administrative databases from fiscal years 2002 to 2009. Study outcomes were uptake rates of laparoscopic surgery, hospital length of stay, 30-day operative mortality, cancer-specific survival, and overall survival. The main descriptor for multivariable regression models was a 5% increase in rate of laparoscopic colon cancer surgery in the previous year. The annual rate of laparoscopic colon and rectal cancer surgery, respectively, rose from 8.7 to 38.9% and from 4.8 to 19.6%. The greatest increase in rate of laparoscopic colon surgery occurred shortly after October 1, 2005. For each 5% increase in rate of laparoscopic surgery, the odds of 30-day mortality was 1.0 [95% confidence interval (CI) 0.96-1.01, p = 0.264], the hazard of cancer-specific survival was 1.0 (95% CI 0.97-1.00, p = 0.139), the hazard of overall survival was 1.0 (95% CI 0.98-1.00, p = 0.051), and length of hospital stay was lower (estimate = -0.10, 95% CI -0.14 to -0.06, p < 0.001). In Ontario by the year 2009, 39% of colon and 20% of rectal cancer surgery was provided laparoscopically. Increased rates were associated with a minimal decrease in hospital length of stay and no changes in 30-day mortality, cancer-specific survival, or overall survival. Financial incentives were likely responsible for the marked increase in laparoscopic colon cancer surgery observed after October 1, 2005.

Would vaccination against nicotine be a cost-effective way to prevent smoking uptake in adolescents?

PubMed

Gartner, Coral E; Barendregt, Jan J; Wallace, Angela; Hall, Wayne D

2012-04-01

We used epidemiological modelling to assess whether nicotine vaccines would be a cost-effective way of preventing smoking uptake in adolescents. We built an epidemiological model using Australian data on age-specific smoking prevalence; smoking cessation and relapse rates; life-time sex-specific disability-adjusted life years lived for cohorts of 100,000 smokers and non-smokers; government data on the costs of delivering a vaccination programme by general practitioners; and a range of plausible and optimistic estimates of vaccine cost, efficacy and immune response rates based on clinical trial results. We first estimated the smoking uptake rates for Australians aged 12-19 years. We then used these estimates to predict the expected smoking prevalence in a birth cohort aged 12 in 2003 by age 20 under (i) current policy and (ii) different vaccination scenarios that varied in cost, initial vaccination uptake, yearly re-vaccination rates, efficacy and a favourable vaccine immune response rate. Under the most optimistic assumptions, the cost to avert a smoker at age 20 was $44,431 [95% confidence interval (CI) $40,023-49,250]. This increased to $296,019 (95% CI $252,307-$355,930) under more plausible scenarios. The vaccine programme was not cost-effective under any scenario. A preventive nicotine vaccination programme is unlikely to be cost-effective. The total cost of a universal vaccination programme would be high and its impact on population smoking prevalence negligible. For these reasons, such a programme is unlikely to be publicly funded in Australia or any other developed country. © 2011 The Authors, Addiction © 2011 Society for the Study of Addiction.

Investigating the inhibitory effect of cyanide, phenol and 4-nitrophenol on the activated sludge process employed for the treatment of petroleum wastewater.

PubMed

Inglezakis, V J; Malamis, S; Omirkhan, A; Nauruzbayeva, J; Makhtayeva, Z; Seidakhmetov, T; Kudarova, A

2017-12-01

In this work, the inhibitory effect of cyanide, phenol and 4-nitrophenol on the activated sludge process was investigated. The inhibition of the aerobic oxidation of organic matter, nitrification and denitrification were examined in batch reactors by measuring the specific oxygen uptake rate (sOUR), the specific ammonium uptake rate (sAUR) and the specific nitrogen uptake rate (sNUR) respectively. The tested cyanide, phenol and 4-nitrophenol concentrations were 0.2-1.7 mg/L, 4.8-73.1 mg/L and 8.2-73.0 mg/L respectively. Cyanide was highly toxic as it significantly (>50%) inhibited the activity of autotrophic biomass, heterotrophic biomass under aerobic conditions and denitrifiers even at relatively low concentrations (1.0-1.7 mgCN - /L). The determination of the half maximum inhibitory concentration (IC 50 ) confirmed this, since for cyanide IC 50 values were very low for the examined bioprocesses (<1.5 mg/L). On the other hand, the IC 50 values for phenol and 4-nitrophenol were much higher (>25 mg/L) for the tested bioprocesses since appreciable concentrations were required to accomplish significant inhibition. The autotrophic bacteria were more sensitive to phenol than the aerobic heterotrophs. The denitrifiers were found to be very resistant to phenol. Copyright © 2016. Published by Elsevier Ltd.

Amino acid uptake by temperate tree species characteristic of low- and high-fertility habitats.

PubMed

Scott, Emily E; Rothstein, David E

2011-10-01

The relationship between inorganic nitrogen (N) cycling and plant productivity is well established. However, recent research has demonstrated the ability of plants to take up low molecular weight organic N compounds (i.e., amino acids) at rates that often rival those of inorganic N forms. In this study, we hypothesize that temperate forest tree species characteristic of low-fertility habitats will prefer amino acids over species characteristic of high-fertility habitats. We measured the uptake of (15)N-labeled amino acids (glycine, glutamine, arginine, serine), ammonium (NH(4)(+)), and nitrate (NO(3)(-)) by four tree species that commonly occur in eastern North America, where their abundances have been correlated with inorganic N availability. Specific uptake rates of amino acids were largely similar for all tree species; however, high-fertility species took up NH(4)(+) at rates more than double those of low-fertility species, rendering amino acid N relatively more important to the N nutrition of low-fertility species. Low-fertility species acquired over four times more total N from arginine compared to NH(4)(+) and NO(3)(-); high-fertility species acquired the most N from NH(4)(+). Arginine had the highest uptake rates of any amino acid by all species; there were no significant differences in uptake rates of the remaining amino acids. Our results support the idea that the dominant species in a particular habitat are those best able to utilize the most available N resources.

Determination of deployment specific chemical uptake rates for SDB-RPD Empore disk using a passive flow monitor (PFM).

PubMed

O'Brien, Dominique; Bartkow, Michael; Mueller, Jochen F

2011-05-01

The use of the adsorbent styrenedivinylbenzene-reverse phase sulfonated (SDB-RPD) Empore disk in a chemcatcher type passive sampler is routinely applied in Australia when monitoring herbicides in aquatic environments. One key challenge in the use of passive samplers is mitigating the potentially confounding effects of varying flow conditions on chemical uptake by the passive sampler. Performance reference compounds (PRCs) may be applied to correct sampling rates (R(s)) for site specific changed in flow and temperature however evidence suggests the use of PRCs is unreliable when applied to adsorbent passive samplers. The use of the passive flow monitor (PFM) has been introduced for the assessment of site-specific changes in water flow. In the presented study we have demonstrated that the R(s) at which both atrazine and prometryn are accumulated within the SDB-RPD-Empore disk is dependent on the flow conditions. Further, the calibration of the measured R(s) for chemical uptake by the SDB-RPD-Empore disk to the mass lost from the PFM has shown that the PFM provides an accurate measure of R(s) for flow velocities from 0 to 16cms(-1). Notably, for flow rates >16cms(-1), a non linear increase in the R(s) of both herbicides was observed which indicates that the key resistance to uptake into the SDB-RPD Empore disk is associated with the diffusion through the overlying diffusion limiting membrane. Overall the greatest uncertainty remains at very low flow conditions, which are unlikely to often occur in surface waters. Validation of the PFM use has also been undertaken in a limited field study. Copyright © 2011 Elsevier Ltd. All rights reserved.

Radio-manganese, -iron, -phosphorus uptake by water hyacinth and economic implications

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

Colley, T.N.; Gonzalez, M.H.; Martin, D.F.

To determine the effects of the deprivation of specific micronutrients on the water hyacinth (Eichhornia crassipes), the rate of uptake by the water hyacinth of iron and manganese in comparison with phosphorus was studied. Materials and methodology are described. Experimentation indicates that all three elements are actively absorbed by the root systems, but the rates of absorption differ markedly. The rate of absorption of manganese by roots is 13 and 21 times that for radio-iron and -phosphorous, and iron was taken up by the roots at nearly twice the rate of phosphorous. Manganese translocation appeared to be faster than phosphorusmore » translocation by an order of magnitude and 65 times faster than iron translocation. 9 references, 2 tables.« less

Carbon allocation and nitrogen acquisition in a developing Populus deltoides plantation

Treesearch

Mark D. Coleman; Christel C. Kern

2004-01-01

We established Populus deltoides Bartr. stands differing in nitrogen (N) availability and tested if: (1) N-induced carbon (C) allocation could be explained by develop- mental allocation controls; and (2) N uptake per unit root mass, i.e., specific N-uptake rate, increased with N availability. Closely spaced (1 × 1 m) stands were treated with 50, 100 and 200 kg N ha ­...

Amino acid metabolism in the human fetus at term: leucine, valine, and methionine kinetics.

PubMed

van den Akker, Chris H P; Schierbeek, Henk; Minderman, Gardi; Vermes, Andras; Schoonderwaldt, Ernst M; Duvekot, Johannes J; Steegers, Eric A P; van Goudoever, Johannes B

2011-12-01

Human fetal metabolism is largely unexplored. Understanding how a healthy fetus achieves its fast growth rates could eventually play a pivotal role in improving future nutritional strategies for premature infants. To quantify specific fetal amino acid kinetics, eight healthy pregnant women received before elective cesarean section at term, continuous stable isotope infusions of the essential amino acids [1-13C,15N]leucine, [U-13C5]valine, and [1-13C]methionine. Umbilical blood was collected after birth and analyzed for enrichments and concentrations using mass spectrometry techniques. Fetuses showed considerable leucine, valine, and methionine uptake and high turnover rates. α-Ketoisocaproate, but not α-ketoisovalerate (the leucine and valine ketoacids, respectively), was transported at net rate from the fetus to the placenta. Especially, leucine and valine data suggested high oxidation rates, up to half of net uptake. This was supported by relatively low α-ketoisocaproate reamination rates to leucine. Our data suggest high protein breakdown and synthesis rates, comparable with, or even slightly higher than in premature infants. The relatively large uptakes of total leucine and valine carbon also suggest high fetal oxidation rates of these essential branched chain amino acids.

The significance of denitrifying polyphosphate accumulating organisms in biological nutrient removal activated sludge systems.

PubMed

Hu, Z R; Wentzel, M C; Ekama, G A

2002-01-01

In this paper the advantages and disadvantages of denitrifying PAOs (polyphosphate accumulating organisms) in conventional BNRAS (biological nutrient removal activated sludge) and external nitrification BNRAS (ENBNRAS) systems are evaluated, with experimental data exhibiting a range of anoxic P uptake from low (<10%) to very high (>60%). The results indicate that the specific denitrification rate of the PAOs on internally stored PHB COD is about 1/5th of that of the "ordinary" heterotrophic organisms on SBCOD, and the PAOs contribute little (maximum 20%) to the denitrification in BNRAS systems even when the anoxic P uptake is high (60% of the total P uptake). Considering the unpredictable nature of anoxic P uptake and the reduction in BEPR it causes compared with aerobic P uptake BEPR, it is concluded that anoxic P uptake does not add a significant advantage to the BNR system.

Sodium ion-dependent amino acid transport in membrane vesicles of Bacillus stearothermophilus.

PubMed Central

Heyne, R I; de Vrij, W; Crielaard, W; Konings, W N

1991-01-01

Amino acid transport in membrane vesicles of Bacillus stearothermophilus was studied. A relatively high concentration of sodium ions is needed for uptake of L-alanine (Kt = 1.0 mM) and L-leucine (Kt = 0.4 mM). In contrast, the Na(+)-H(+)-L-glutamate transport system has a high affinity for sodium ions (Kt less than 5.5 microM). Lithium ions, but no other cations tested, can replace sodium ions in neutral amino acid transport. The stimulatory effect of monensin on the steady-state accumulation level of these amino acids and the absence of transport in the presence of nonactin indicate that these amino acids are translocated by a Na+ symport mechanism. This is confirmed by the observation that an artificial delta psi and delta mu Na+/F but not a delta pH can act as a driving force for uptake. The transport system for L-alanine is rather specific. L-Serine, but not L-glycine or other amino acids tested, was found to be a competitive inhibitor of L-alanine uptake. On the other hand, the transport carrier for L-leucine also translocates the amino acids L-isoleucine and L-valine. The initial rates of L-glutamate and L-alanine uptake are strongly dependent on the medium pH. The uptake rates of both amino acids are highest at low external pH (5.5 to 6.0) and decline with increasing pH. The pH allosterically affects the L-glutamate and L-alanine transport systems. The maximal rate of L-glutamate uptake (Vmax) is independent of the external pH between pH 5.5 and 8.5, whereas the affinity constant (Kt) increases with increasing pH. A specific transport system for the basic amino acids L-lysine and L-arginine in the membrane vesicles has also been observed. Transport of these amino acids occurs most likely by a uniport mechanism. PMID:1670936

Ammonium and nitrate uptake by soybean during recovery from nitrogen deprivation

NASA Technical Reports Server (NTRS)

Rideout, J. W.; Chaillou, S.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

1994-01-01

Soybean [Glycine max (L.) Merrill] plants that had been subjected to 15 d of nitrogen deprivation were resupplied for 10 d with 1.0 mol m-3 nitrogen provided as NO3-, NH4+, or NH4(+) + NO3- in flowing hydroponic culture. Plants in a fourth hydroponic system received 1.0 mol m-3 NO3- during both stress and resupply periods. Concentrations of soluble carbohydrates and organic acids in roots increased 210 and 370%, respectively, during stress. For the first day of resupply, however, specific uptake rates of nitrogen, determined by ion chromatography as depletion from solution, were lower for stressed than for non-stressed plants by 43% for NO3- resupply, by 32% for NH4(+) + NO3- resupply, and 86% for NH4+ resupply. When specific uptake of nitrogen for stressed plants recovered to rates for non-stressed plants at 6 to 8 d after nitrogen resupply, carbohydrates and organic acids in their roots had declined to concentrations lower than those of non-stressed plants. Recovery of nitrogen uptake capacity of roots thus does not appear to be regulated simply by the content of soluble carbon compounds within roots. Solution concentrations of NH4+ and NO3- were monitored at 62.5 min intervals during the first 3 d of resupply. Intermittent 'hourly' intervals of net influx and net efflux occurred. Rates of uptake during influx intervals were greater for the NH4(+)-resupplied than for the NO3(-)-resupplied plants. For NH4(+)-resupplied plants, however, the hourly intervals of efflux were more numerous than for NO3(-)-resupplied plants. It thus is possible that, instead of repressing NH4+ influx, increased accumulation of amino acids and NH4+ in NH4(+)-resupplied plants inhibited net uptake by stimulation of efflux on NH4+ absorbed in excess of availability of carbon skeletons for assimilation. Entry of NH4+ into root cytoplasm appeared to be less restricted than translocation of amino acids from the cytoplasm into the xylem.

Impact of phosphate limitation on PHA production in a feast-famine process.

PubMed

Korkakaki, Emmanouela; van Loosdrecht, Mark C M; Kleerebezem, Robbert

2017-12-01

Double-limitation systems have shown to induce polyhydroxyalkanoates (PHA) production in chemostat studies limited in e.g. carbon and phosphate. In this work the impact of double substrate limitation on the enrichment of a PHA producing community was studied in a sequencing batch process. Enrichments at different C/P concentration ratios in the influent were established and the effect on the PHA production capacity and the enrichment community structure was investigated. Experimental results demonstrated that when a double substrate limitation is imposed at a C/P ratio in the influent in a range of 150 (C-mol/mol), the P-content of the biomass and the specific substrate uptake rates decreased. Nonetheless, the PHA storage capacity remained high (with a maximum of 84 wt%). At a C/P ratio of 300, competition in the microbial community is based on phosphate uptake, and the PHA production capacity is lost. Biomass specific substrate uptake rates are a linear function of the cellular P-content, offering advantages for scaling-up the PHA production process due to lower oxygen requirements. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gill structural change in response to turbidity has no effect on the oxygen uptake of a juvenile sparid fish.

PubMed

Cumming, H; Herbert, N A

2016-01-01

Turbidity as a result of increased suspended sediments in coastal waters is an environmental stress of worldwide concern. Recent research on fish suggests that detrimental changes to gill structure can occur in turbid waters, with speculation that these alterations diminish fitness variables, such as growth and development, by negatively impacting the O 2 uptake capacity (respiration) of fish. Specifically to address this unknown, the impact of turbid water on the gill structure, somatic growth rate and O 2 uptake rates of a juvenile sparid species ( Pagrus auratus ) was addressed following exposure to five different turbidity treatments (<10, 20, 40, 60 or 80 nephelometric turbidity units) for 30 days. Significant gill structural change was apparent with a progressive increase in turbidity and was quantified as a reduction in lamellar density, as well as an increase in basal hyperplasia, epithelial lifting and increased oxygen diffusion distance across the lamellae. The weight of control fish did not change throughout the experiment, but all fish exposed to turbid waters lost weight, and weight loss increased with nephelometric turbidity units, confirming that long-term turbidity exposure is detrimental to growth productivity. The growth of fish could be impacted in a variety of ways, but the specific hypothesis that structural alteration of the gills impairs O 2 uptake across the gills and limits growth fitness was not supported because there was no measurable difference in the standard metabolic rate, maximal metabolic rate, aerobic metabolic scope or critical oxygen saturation limit of fish measured in clear water after 30 days of exposure. Although impaired O 2 uptake as a result of structurally adjusted gills is unlikely to be the cause of poor fish growth, the exact mechanism by which growth productivity is affected in turbid conditions remains unclear and warrants further investigation.

Gill structural change in response to turbidity has no effect on the oxygen uptake of a juvenile sparid fish

PubMed Central

Cumming, H.; Herbert, N. A.

2016-01-01

Turbidity as a result of increased suspended sediments in coastal waters is an environmental stress of worldwide concern. Recent research on fish suggests that detrimental changes to gill structure can occur in turbid waters, with speculation that these alterations diminish fitness variables, such as growth and development, by negatively impacting the O2 uptake capacity (respiration) of fish. Specifically to address this unknown, the impact of turbid water on the gill structure, somatic growth rate and O2 uptake rates of a juvenile sparid species (Pagrus auratus) was addressed following exposure to five different turbidity treatments (<10, 20, 40, 60 or 80 nephelometric turbidity units) for 30 days. Significant gill structural change was apparent with a progressive increase in turbidity and was quantified as a reduction in lamellar density, as well as an increase in basal hyperplasia, epithelial lifting and increased oxygen diffusion distance across the lamellae. The weight of control fish did not change throughout the experiment, but all fish exposed to turbid waters lost weight, and weight loss increased with nephelometric turbidity units, confirming that long-term turbidity exposure is detrimental to growth productivity. The growth of fish could be impacted in a variety of ways, but the specific hypothesis that structural alteration of the gills impairs O2 uptake across the gills and limits growth fitness was not supported because there was no measurable difference in the standard metabolic rate, maximal metabolic rate, aerobic metabolic scope or critical oxygen saturation limit of fish measured in clear water after 30 days of exposure. Although impaired O2 uptake as a result of structurally adjusted gills is unlikely to be the cause of poor fish growth, the exact mechanism by which growth productivity is affected in turbid conditions remains unclear and warrants further investigation. PMID:27766155

Inhibitory effect of cyanide on wastewater nitrification determined using SOUR and RNA-based gene-specific assays

EPA Science Inventory

The effect of CN- (CN-) on nitrification was examined with samples from nitrifying wastewater enrichments using two different approaches: by measuring substrate (ammonia) specific oxygen uptake rates (SOUR), and by using RT-qPCR to quantify the transcripts of functional genes inv...

Temperature and pH effects on plant uptake of benzotriazoles by sunflowers in hydroponic culture.

PubMed

Castro, Sigifredo; Davis, Lawrence C; Erickson, Larry E

2004-01-01

This article describes a systematic approach to understanding the effect of environmental variables on plant uptake (phyto-uptake) of organic contaminants. Uptake (and possibly phytotransformation) of xenobiotics is a complex process that may differ from nutrient uptake. A specific group of xenobiotics (benzotriazoles) were studied using sunflowers grown hydroponically with changes of environmental conditions including solution volume, temperature, pH, and mixing. The response of plants to these stimuli was evaluated and compared using physiological changes (biomass production and water uptake) and estimated uptake rates (influx into plants), which define the uptake characteristics for the xenobiotic. Stirring of the hydroponic solution had a significant impact on plant growth and water uptake. Plants were healthier, probably because of a combination of factors such as improved aeration and increase in temperature. Uptake and possibly phytotransformation of benzotriazoles was increased accordingly. Experiments at different temperatures allowed us to estimate an activation energy for the reaction leading to triazole disappearance from the solution. The estimated activation energy was 43 kJ/mol, which indicates that the uptake process is kinetically limited. Culturing plants in triazole-amended hydroponic solutions at different pH values did not strongly affect the biomass production, water uptake, and benzotriazole uptake characteristics. The sunflowers showed an unexpected capacity to buffer the solution pH.

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

Isotopic and enzymatic analyses of planktonic nitrogen utilisation in the vicinity of Cape Sines (Portugal) during weak upwelling activity

NASA Astrophysics Data System (ADS)

Slawyk, Gerd; Coste, Bernard; Collos, Yves; Rodier, Martine

1997-01-01

Using measurements of 15N uptake and activities of nitrate reductase and glutamine synthetase, the utilization of nitrogenous nutrients by microplankton in the Portuguese upwelling area was investigated. During this cruise the euphotic zone of coastal waters was in most cases bisected by a nitracline forming two layers. Total inorganic nitrogen uptake rates (NH 4+ + NO 3-) in the upper mixed and nitrate-impoverished layer ranged from 0.1 to 0.8 nM h -1 and were primarily supported by regenerated (ammonium) nitrogen (62-97%), whereas they varied between 0.9 and 10.4 nM h -1 in the deep nitrate-rich layer and were mainly driven by new (nitrate) nitrogen (52-82%). Depth profiles of Chl a-specific uptake rates for ammonium and nitrate paralleled those of absolute uptake rates, i.e. values of VNH 4+Chl were highest (up to 16.1 nmol μg -1 h -1) in nitrate-poor surface waters while values of VNO 3-Chl were maximum (up to 8.4 nmol μg -1 h -1)within the nitracline. This latter vertical ordering of planktonic nitrogen nutrition was consistent with an aged upwelling situation. However, applying several indices of cell metabolism and nutritional status, such as 15N uptake/enzyme activity, surge uptake internally controlled uptake, and V maxChl/K t ratios, we were able to demonstrate that the phytoplankton assemblages inhabiting the nutrient-impoverished upper layer still bore the signature of physically mediated nitrogen (nitrate) supply generated by active upwelling that had occurred during the week before our visit to the area. This signature was the most evident in samples from the station furthest inshore and faded with distance from shore as a result of the deepening of the nitrate isopleths (weakening of upwelling activity), which showed the same offshore trend. The appearance of nitrate-rich waters at the surface, after a strong pulse of upwelling favourable winds just before the end of the cruise, led to a five-fold increase in average (over the euphotic zone) absolute and Chl a-specific nitrate uptake rates (10.4 nM h -1, 7.5 nmol μ -1 h -1) compared to the mean rates during weak upwelling (1.7 nM h -1, 1.5 nmol μ -1 h -1). From a comparison with the neighbouring Moroccan upwelling, it is assumed that new production in the Portuguese upwelling averages 50 nM h -1. Thus, this upwelling would rank with the northwest African upwelling system off Cape Blanc or with the Californian upwelling at Point Conception for the capacity of new production, but seems to be much less efficient (seven-fold) than the highly permanent Peru upwelling.

Adult immunisation: A key element of public health programs: Synopsis of Asia Pacific Adult Immunisation Meeting, Tokyo, 1-2 December 2016.

PubMed

Rochman-Fowler, Jessica; Duarte Walsh, Virginia; Barratt, Jane

2018-06-01

To (i) improve scientific knowledge and understanding of the importance of adult vaccination within a public health framework; (ii) share an understanding of the principles of good practice that have improved adult vaccination uptake rates; (iii) appreciate the diverse nature of country-specific barriers; and (iv) reach consensus on principles of a call to action to increase adult vaccination uptake rates. Non-governmental organisations, the International Federation on Ageing and Friends of International Federation on Ageing Japan, convened the Asia Pacific Adult Immunisation Meeting, herein referred to as the 'Asia Pacific Meeting'. Delegates identified fundamental barriers to adult vaccination similar to those reported at previous meetings in Latin America and Europe and formed a road map to respond to key barriers in countries represented at the Asia Pacific Meeting. Older people are uniquely vulnerable to vaccine-preventable diseases and therefore need to be the target of a series of actions intended to improve uptake rates in this subpopulation. © 2018 AJA Inc.

Effectiveness of Vegetated Drainage Ditches for Domestic Sewage Effluent Mitigation.

PubMed

Kumwimba, Mathieu Nsenga; Zhu, Bo

2017-05-01

Plant species have an important role in eco-ditches; however, the Michaelis-Menten kinetic parameters of nutrient uptake, growth rate and purification efficiency of ditch plants and their influences on domestic sewage treatment efficiency are still unclear. Growth rates of all nine species, but especially Lemna gibba, Cladophora and Myriophyllum verticillatum were best in undiluted domestic sewage as opposed to a mixture of domestic sewage. Performance of species to accumulate nutrients was not only species-specific, but was also affected by both sewage treatments. Removal efficiency of nutrients was dependent on both plant species and treatment. Uptake kinetic parameters were significantly affected by both nutrient form and plant species. The maximum uptake rate (Vmax) of NH 4 -N was higher than NO 3 -N. Similarly, Km values for NH 4 -N were greater than NO 3 -N. These results could be used to identify plants for sewage treatment efficiency and enhance water quality in eco-ditch treatment systems.

The effect and biological mechanism of granular sludge size on performance of autotrophic nitrogen removal system.

PubMed

Ya-Juan, Xing; Jun-Yuan, Ji; Ping, Zheng; Lan, Wang; Abbas, Ghulam; Zhang, Jiqiang; Ru, Wang; Zhan-Fei, He

2018-05-31

The autotrophic process for nitrogen removal has attracted worldwide attention in the field of wastewater treatment, and the performance of this process is greatly influenced by the size of granular sludge particles present in the system. In this work, the granular sludge was divided into three groups, i.e. large size (> 1.2 mm), medium size (0.6-1.2 mm) and small size (< 0.6 mm). The medium granular sludge was observed to dominate at high volumetric nitrogen loading rates, while offering strong support for good performance. Its indispensable contribution was found to originate from improved settling velocity (0.84 ± 0.10 cm/s), high SOUR-A (specific oxygen uptake rate for ammonia oxidizing bacteria, 25.93 mg O 2 /g MLVSS/h), low SOUR-N (specific oxygen uptake rate for nitrite oxidizing bacteria, 3.39 mg O 2 /g MLVSS/h), and a reasonable microbial spatial distribution.

Comparative Computational Modeling of Airflows and Vapor Dosimetry in the Respiratory Tracts of Rat, Monkey, and Human

PubMed Central

Corley, Richard A.

2012-01-01

Computational fluid dynamics (CFD) models are 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. We improved the imaging and model development methods to the point where CFD models for the rat, monkey, and human now encompass airways from the nose or mouth to the lung. A total of 1272, 2172, and 135 pulmonary airways representing 17±7, 19±9, or 9±2 airway generations were included in the rat, monkey and human models, respectively. A CFD/physiologically based pharmacokinetic model previously developed for acrolein was adapted for these anatomically correct extended airway models. Model parameters were obtained from the literature or measured directly. Airflow and acrolein uptake patterns were determined under steady-state inhalation conditions to provide direct comparisons with prior data and nasal-only simulations. Results confirmed that regional uptake was sensitive to airway geometry, airflow rates, acrolein concentrations, air:tissue partition coefficients, tissue thickness, and the maximum rate of metabolism. Nasal extraction efficiencies were predicted to be greatest in the rat, followed by the monkey, and then the human. For both nasal and oral breathing modes in humans, higher uptake rates were predicted for lower tracheobronchial tissues than either the rat or monkey. These extended airway models provide a unique foundation for comparing material transport and site-specific tissue uptake across a significantly greater range of conducting airways in the rat, monkey, and human than prior CFD models. PMID:22584687

Effect of Caffeine Ingestion on Cardiorespiratory Endurance in Men and Women.

ERIC Educational Resources Information Center

Butts, N. K.; Crowell, D.

1985-01-01

Oxygen uptake, heart rate, and rating of perceived exertion were used to measure the effect of caffeine ingestion on active college students. The results do not support the general use of caffeine as an ergogenic aid for either males or females, although caffeine may have that effect on specific individuals. (Author/MT)

Effect of heavy metals on nitrification activity as measured by RNA- and DNA-based function-specific assays

EPA Science Inventory

Heavy metals can inhibit nitrification, a key process for nitrogen removal in wastewater treatment. The transcriptional responses of functional genes (amoA, hao, nirK and norB) were measured in conjunction with specific oxygen uptake rate (sOUR) for nitrifying enrichment cultures...

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.

Quantifying root water extraction after drought recovery using sub-mm in situ empirical data

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

Dhiman, Indu; Bilheux, Hassina Z.; DeCarlo, Keito F.

Root-specific responses to stress are not well-known, and have been largely based on indirect measurements of bulk soil water extraction, which limits mechanistic modeling of root function. Here, we used neutron radiography to examine in situ root-soil water dynamics of a previously droughted black cottonwood ( Populus trichocarpa) seedling, contrasting water uptake by younger, thinner or older, thicker parts of the fine root system. The smaller diameter roots had greater water uptake capacity per unit surface area than the larger diameter roots, but they had less total surface area leading to less total water extraction; rates ranged from 0.0027 –more » 0.0116 g cm -2 hr -1. The finest most-active roots were not visible in the radiographs, indicating the need to include destructive sampling. Analysis based on bulk soil hydraulic properties indicated substantial redistribution of water via saturated/unsaturated flow, capillary wicking, and root hydraulic redistribution across the layers - suggesting water uptake dynamics following an infiltration event may be more complex than approximated by common soil hydraulic or root surface area modeling approaches. Lastly, our results highlight the need for continued exploration of root-trait specific water uptake rates in situ, and impacts of roots on soil hydraulic properties – both critical components for mechanistic modeling of root function.« less

Quantifying root water extraction after drought recovery using sub-mm in situ empirical data

DOE PAGES

Dhiman, Indu; Bilheux, Hassina Z.; DeCarlo, Keito F.; ...

2017-09-09

Root-specific responses to stress are not well-known, and have been largely based on indirect measurements of bulk soil water extraction, which limits mechanistic modeling of root function. Here, we used neutron radiography to examine in situ root-soil water dynamics of a previously droughted black cottonwood ( Populus trichocarpa) seedling, contrasting water uptake by younger, thinner or older, thicker parts of the fine root system. The smaller diameter roots had greater water uptake capacity per unit surface area than the larger diameter roots, but they had less total surface area leading to less total water extraction; rates ranged from 0.0027 –more » 0.0116 g cm -2 hr -1. The finest most-active roots were not visible in the radiographs, indicating the need to include destructive sampling. Analysis based on bulk soil hydraulic properties indicated substantial redistribution of water via saturated/unsaturated flow, capillary wicking, and root hydraulic redistribution across the layers - suggesting water uptake dynamics following an infiltration event may be more complex than approximated by common soil hydraulic or root surface area modeling approaches. Lastly, our results highlight the need for continued exploration of root-trait specific water uptake rates in situ, and impacts of roots on soil hydraulic properties – both critical components for mechanistic modeling of root function.« less

Cyclic variations in nitrogen uptake rate of soybean plants: effects of pH and mixed nitrogen sources

NASA Technical Reports Server (NTRS)

Raper, C. D. Jr; Vessey, J. K.; Henry, L. T.; Chaillou, S.

1991-01-01

To determine if the daily pattern of NO3- and NH4+ uptake is affected by acidity or NO3- : NH4+ ratio of the nutrient solution, non-nodulated soybean plants (Glycine max) were exposed for 21 days to replenished, complete nutrient solutions at pH 6.0, 5.5, 5.0, and 4.5 which contained either 1.0 mM NH4+, 1.0 mM NO3- [correction of NO3+], 0.67 mM NH4+ plus 0.33 mM NO3- (2:1 NH4+ : NO3-) [correction of (2:1 NH3+ : NO4-)], or 0.33 mM NH4+ plus 0.67 mM NO3- (1:2 NH4+ : NO3-). Net uptake rates of NH4+ and NO3- were measured daily by ion chromatography as depletion from the replenished solutions. When NH4+ and NO3- were supplied together, cumulative uptake of total nitrogen was not affected by pH or solution NH4+ : NO3- ratio. The cumulative proportion of nitrogen absorbed as NH4+ decreased with increasing acidity; however, the proportional uptake of NH4+ and NO3- was not constant, but varied day-to-day. This day-to-day variation in relative proportions of NH4+ and NO3- absorbed when NH4+ : NO3- ratio and pH of solution were constant indicates that the regulatory mechanism is not directly competitive. Regardless of the effect of pH on cumulative uptake of NH4+, the specific nitrogen uptake rates from mixed and from individual NH4+ and NO3- sources oscillated between maxima and minima at each pH with average periodicities similar to the expected interval of leaf emergence.

Methanol induction optimization for scFv antibody fragment production in Pichia pastoris.

PubMed

Cunha, A E; Clemente, J J; Gomes, R; Pinto, F; Thomaz, M; Miranda, S; Pinto, R; Moosmayer, D; Donner, P; Carrondo, M J T

2004-05-20

Fibronectin splice variant ED B (extracellular domain B) is a promising marker for angiogenesis in growing solid tumors. Currently, recombinant antibodies against ED B are being investigated concerning their potential use, for either therapeutic or diagnostic purposes. Single-chain antibody fragments directed against the ED B can be efficiently expressed in Pichia pastoris; thus, a recombinant strain of the methylotropic yeast P. pastoris was used for this work. Three different forms of scFv antibody fragment are found in the supernatant from this fermentation: covalent homodimer, associative homodimer, and monomer. Both homodimeric forms can be converted to the monomeric form (under reducing conditions) and be efficiently radiolabeled, whereas the monomeric form of scFv already present in the supernatant cannot. It was also found that the fraction of protein in the monomeric form is highly dependent on the mode of induction rather than scFv concentration. This suggests that the monomeric form of the scFv present in the supernatant might be a result of events occurring at the expression, secretion, or folding level. A high cell density fermentation protocol was developed by optimizing methanol induction, yielding the highest scFv antibody fragment production rate and product quality; cell concentration at the induction point and specific methanol uptake rate were found to be the most important control variables. A decrease in specific methanol uptake rate led to a higher specific production rate for the scFv antibody fragment (5.4 microg g(cell) h(-1)). Product quality, i.e., percentage of product in a homodimeric form, also increased with the decrease in methanol uptake rate. Furthermore, the volumetric productivity depended on cell concentration at the induction point, increasing with the increase of cell concentration up to 320 g L(-1) wet cell weight (WCW). The reduction of the methanol feeding rate for induction, and consequently of the oxygen uptake rate, have important consequences for optimizing product titers and quality and thus on the scale-up of this production process; hence one of the major limitations upon high cell density cultivation in bioreactors is keeping the high oxygen transfer rate required. From the results obtained, a scale-up strategy was developed based on the available oxygen transfer rates at larger scales, allowing the definition of the optimum biomass concentration for induction and methanol feeding strategy for maximization of product titer and quality. Copyright 2004 Wiley Periodicals, Inc.

Analysis of factors that influence rates of carbon monoxide uptake, distribution, and washout from blood and extravascular tissues using a multicompartment model.

PubMed

Bruce, Margaret C; Bruce, Eugene N

2006-04-01

To better understand factors that influence carbon monoxide (CO) washout rates, we utilized a multicompartment mathematical model to predict rates of CO uptake, distribution in vascular and extravascular (muscle vs. other soft tissue) compartments, and washout over a range of exposure and washout conditions with varied subject-specific parameters. We fitted this model to experimental data from 15 human subjects, for whom subject-specific parameters were known, multiple washout carboxyhemoglobin (COHb) levels were available, and CO exposure conditions were identical, to investigate the contributions of exposure conditions and individual variability to CO washout from blood. We found that CO washout from venous blood was biphasic and that postexposure times at which COHb samples were obtained significantly influenced the calculated CO half times (P < 0.0001). The first, more rapid, phase of CO washout from the blood reflected the loss of CO to the expired air and to a slow uptake by the muscle compartment, whereas the second, slower washout phase was attributable to CO flow from the muscle compartment back to the blood and removal from blood via the expired air. When the model was used to predict the effects of varying exposure conditions for these subjects, the CO exposure duration, concentration, peak COHb levels, and subject-specific parameters each influenced washout half times. Blood volume divided by ventilation correlated better with half-time predictions than did cardiac output, muscle mass, or ventilation, but it explained only approximately 50% of half-time variability. Thus exposure conditions, COHb sampling times, and individual parameters should be considered when estimating CO washout rates for poisoning victims.

Microbial Group Specific Uptake Kinetics of Inorganic Phosphate and Adenosine-5′-Triphosphate (ATP) in the North Pacific Subtropical Gyre

PubMed Central

Björkman, Karin; Duhamel, Solange; Karl, David M.

2012-01-01

We investigated the concentration dependent uptake of inorganic phosphate (Pi) and adenosine-5′-triphosphate (ATP) in microbial populations in the North Pacific Subtropical Gyre (NPSG). We used radiotracers to measure substrate uptake into whole water communities, differentiated microbial size classes, and two flow sorted groups; Prochlorococcus (PRO) and non-pigmented bacteria (NPB). The Pi concentrations, uptake rates, and Pi pool turnover times (Tt) were (mean, ±SD); 54.9 ± 35.0 nmol L−1 (n = 22), 4.8 ± 1.9 nmol L−1 day−1 (n = 19), and 14.7 ± 10.2 days (n = 19), respectively. Pi uptake into >2 μm cells was on average 12 ± 7% (n = 15) of the total uptake. The kinetic response to Pi (10–500 nmol L−1) was small, indicating that the microorganisms were close to their maximum uptake velocity (Vmax). Vmax averaged 8.0 ± 3.6 nmol L−1 day−1 (n = 19) in the >0.2 μm group, with half saturation constants (Km) of 40 ± 28 nmol L−1 (n = 19). PRO had three times the cell specific Pi uptake rate of NPB, at ambient concentrations, but when adjusted to cells L−1 the rates were similar, and these two groups were equally competitive for Pi. The Tt of γ-P-ATP in the >0.2 μm group were shorter than for the Pi pool (4.4 ± 1.0 days; n = 6), but this difference diminished in the larger size classes. The kinetic response to ATP was large in the >0.2 μm class with Vmax exceeding the rates at ambient concentrations (mean 62 ± 27 times; n = 6) with a mean Vmax for γ-P-ATP of 2.8 ± 1.0 nmol L−1 day−1, and Km at 11.5 ± 5.4 nmol L−1 (n = 6). The NPB contribution to γ-P-ATP uptake was high (95 ± 3%, n = 4) at ambient concentrations but decreased to ∼50% at the highest ATP amendment. PRO had Km values 5–10 times greater than NPB. The above indicates that PRO and NPB were in close competition in terms of Pi acquisition, whereas P uptake from ATP could be attributed to NPB. This apparent resource partitioning may be a niche separating strategy and an important factor in the successful co-existence within the oligotrophic upper ocean of the NPSG. PMID:22701449

Unexpected stimulation of soil methane uptake as emergent property of agricultural soils following bio-based residue application.

PubMed

Ho, Adrian; Reim, Andreas; Kim, Sang Yoon; Meima-Franke, Marion; Termorshuizen, Aad; de Boer, Wietse; van der Putten, Wim H; Bodelier, Paul L E

2015-10-01

Intensification of agriculture to meet the global food, feed, and bioenergy demand entail increasing re-investment of carbon compounds (residues) into agro-systems to prevent decline of soil quality and fertility. However, agricultural intensification decreases soil methane uptake, reducing, and even causing the loss of the methane sink function. In contrast to wetland agricultural soils (rice paddies), the methanotrophic potential in well-aerated agricultural soils have received little attention, presumably due to the anticipated low or negligible methane uptake capacity in these soils. Consequently, a detailed study verifying or refuting this assumption is still lacking. Exemplifying a typical agricultural practice, we determined the impact of bio-based residue application on soil methane flux, and determined the methanotrophic potential, including a qualitative (diagnostic microarray) and quantitative (group-specific qPCR assays) analysis of the methanotrophic community after residue amendments over 2 months. Unexpectedly, after amendments with specific residues, we detected a significant transient stimulation of methane uptake confirmed by both the methane flux measurements and methane oxidation assay. This stimulation was apparently a result of induced cell-specific activity, rather than growth of the methanotroph population. Although transient, the heightened methane uptake offsets up to 16% of total gaseous CO2 emitted during the incubation. The methanotrophic community, predominantly comprised of Methylosinus may facilitate methane oxidation in the agricultural soils. While agricultural soils are generally regarded as a net methane source or a relatively weak methane sink, our results show that methane oxidation rate can be stimulated, leading to higher soil methane uptake. Hence, even if agriculture exerts an adverse impact on soil methane uptake, implementing carefully designed management strategies (e.g. repeated application of specific residues) may compensate for the loss of the methane sink function following land-use change. © 2015 John Wiley & Sons Ltd.

Metabolic rate in different rat brain areas during seizures induced by a specific delta opiate receptor agonist.

PubMed

Haffmans, J; De Kloet, R; Dzoljic, M R

1984-06-04

The glucose utilization during specific delta opiate agonist-induced epileptiform phenomena, determined by the [14C]2-deoxyglucose technique (2-DG), was examined in various rat brain areas at different time intervals. The peak in EEG spiking response and the most intensive 2-DG uptake occurred 5 min after intraventricular (i.v.t.) administration of the delta opiate receptor agonist. The most pronounced 2-DG uptake at this time interval can be observed in the subiculum, including the CA1 hippocampal area, frontal cortex and central amygdala. A general decrease of glucose consumption, compared to control values, is observed after 10 min, in all regions, with exception of the subiculum. Since functional activity and 2-DG uptake are correlated, we suggest that the subiculum and/or CA1 area, are probably the brain regions most involved in the enkephalin-induced epileptic phenomena.

Evaluation of Populus and Salix continuously irrigated with landfill leachate I. Genotype-specific elemental phytoremediation.

PubMed

Zalesny, Ronald S; Bauer, Edmund O

2007-01-01

There is a need for the identification and selection of specific tree genotypes that can sequester elements from contaminated soils, with elevated rates of uptake. We irrigated Populus (DN17, DN182, DN34, NM2, NM6) and Salix (94003, 94012, S287, S566, SX61) genotypes planted in large soil-filled containers with landfill leachate or municipal water and tested for differences in inorganic element concentrations (P, K, Ca, Mg, S, Zn, B, Mn, Fe, Cu, Al, Na, and Cl) in the leaves, stems, and roots. Trees were irrigated with leachate or water during the final 12 wk of the 18-wk study. Genotype-specific uptake existed. For genera, tissue concentrations exhibited four responses. First, Populus had the greatest uptake of P, K, S, Cu, and Cl. Second, Salix exhibited the greatest uptake of Zn, B, Fe, and Al. Third, Salix had greater concentrations of Ca and Mg in leaves, while Populus had greater concentrations in stems and roots. Fourth, Populus had greater concentrations of Mn and Na in leaves and stems, while Salix had greater concentrations in roots. Populus deltoides x P. nigra clones exhibited better overall phytoremediation than the P. nigra x P. maximowiczii genotypes tested. Phytoremediation for S. purpurea clones 94003 and 94012 was generally less than for other Salix genotypes. Overall, concentrations of elements in the leaves, stems, and roots corroborated those in the plant-sciences literature. Uptake was dependent upon the specific genotype for most elements. Our results corroborated the need for further testing and selecting of specific clones for various phytoremediation needs, while providing a baseline for future researchers developing additional studies and resource managers conducting on-site remediation.

Recombinant protein expression in Pichia pastoris strains with an engineered methanol utilization pathway

PubMed Central

2012-01-01

Βackground The methylotrophic yeast Pichia pastoris has become an important host organism for recombinant protein production and is able to use methanol as a sole carbon source. The methanol utilization pathway describes all the catalytic reactions, which happen during methanol metabolism. Despite the importance of certain key enzymes in this pathway, so far very little is known about possible effects of overexpressing either of these key enzymes on the overall energetic behavior, the productivity and the substrate uptake rate in P. pastoris strains. Results A fast and easy-to-do approach based on batch cultivations with methanol pulses was used to characterize different P. pastoris strains. A strain with MutS phenotype was found to be superior over a strain with Mut+ phenotype in both the volumetric productivity and the efficiency in expressing recombinant horseradish peroxidase C1A. Consequently, either of the enzymes dihydroxyacetone synthase, transketolase or formaldehyde dehydrogenase, which play key roles in the methanol utilization pathway, was co-overexpressed in MutS strains harboring either of the reporter enzymes horseradish peroxidase or Candida antarctica lipase B. Although the co-overexpression of these enzymes did not change the stoichiometric yields of the recombinant MutS strains, significant changes in the specific growth rate, the specific substrate uptake rate and the specific productivity were observed. Co-overexpression of dihydroxyacetone synthase yielded a 2- to 3-fold more efficient conversion of the substrate methanol into product, but also resulted in a reduced volumetric productivity. Co-overexpression of formaldehyde dehydrogenase resulted in a 2-fold more efficient conversion of the substrate into product and at least similar volumetric productivities compared to strains without an engineered methanol utilization pathway, and thus turned out to be a valuable strategy to improve recombinant protein production. Conclusions Co-overexpressing enzymes of the methanol utilization pathway significantly affected the specific growth rate, the methanol uptake and the specific productivity of recombinant P. pastoris MutS strains. A recently developed methodology to determine strain specific parameters based on dynamic batch cultivations proved to be a valuable tool for fast strain characterization and thus early process development. PMID:22330134

Ammonium and nitrate uptake by leaves of the seagrass Thalassia testudinum: impact of hydrodynamic regime and epiphyte cover on uptake rates

NASA Astrophysics Data System (ADS)

Cornelisen, Christopher D.; Thomas, Florence I. M.

2004-08-01

Seagrasses rely on the uptake of dissolved inorganic nitrogen (DIN) from both sediment pore water and the water column for metabolic processes. Rates at which their leaves remove nutrients from the water column may be influenced by physiological factors, such as enzyme kinetics, and physical factors, including water flow and the presence of epiphytes on the leaf surface. While there is some evidence of the individual effects of these factors on uptake rates for individual plants, there is little information on the effects of these factors on seagrasses that are situated in their natural environment. In order to isolate the combined effects of water flow and epiphyte cover on uptake rates for Thalassia testudinum leaves while they were situated in a natural canopy we applied 15N-labeled ammonium and 15N-labeled nitrate in a series of field flume experiments. Hydrodynamic parameters related to thickness of diffusive boundary layers, including bottom shear stress and the rate of turbulent energy dissipation, were estimated from velocity profiles collected with an acoustic Doppler velocimeter. Rates of NH 4+ uptake for leaves with and without epiphyte cover were proportional to bottom shear stress and energy dissipation rate, while rates of NO 3- uptake were not. For epiphytes, rates of both NH 4+ and NO 3- uptake were dependent on hydrodynamic parameters. Epiphytes covering the leaf surface reduced rates of NH 4+ uptake for seagrass leaves by an amount proportional to the spatial area covered by the epiphytes (˜90%) and although epiphytes reduced NO 3- uptake rates, the amount was not proportional to the extent of epiphyte cover. Results suggest that the rate at which seagrass leaves removed ammonium was limited by the rate of delivery to the surface of the leaves and was greatly reduced due to blockage of active uptake sites by epiphytes. Conversely, rates of nitrate uptake for the seagrass leaves were limited by the rate at which the leaves could process nitrate rather than the rate of delivery. Our findings quantitatively demonstrate the potential impact of hydrodynamic regime and epiphyte cover on rates of DIN uptake by T. testudinum leaves and how the importance of these factors in affecting uptake rates can vary depending on the form of DIN being assimilated.

Specific cesium transport via the Escherichia coli Kup (TrkD) K+ uptake system.

PubMed Central

Bossemeyer, D; Schlösser, A; Bakker, E P

1989-01-01

Escherichia coli cells which contain a functional Kup (formerly TrkD) system took up Cs+ with a moderate rate and affinity. Kup is a separate K+ uptake system with relatively little discrimination in the transport of the cations K+, Rb+, and Cs+. Regardless of the presence or absence of Kup, K+-replete cells took up Cs+ primarily by a very low affinity mode, proportional to the ratio of the Cs+ and K+ concentrations in the medium. PMID:2649491

Specific light uptake rates can enhance astaxanthin productivity in Haematococcus lacustris.

PubMed

Lee, Ho-Sang; Kim, Z-Hun; Park, Hanwool; Lee, Choul-Gyun

2016-05-01

Lumostatic operation was applied for efficient astaxanthin production in autotrophic Haematococcus lacustris cultures using 0.4-L bubble column photobioreactors. The lumostatic operation in this study was performed with three different specific light uptake rates (q(e)) based on cell concentration, cell projection area, and fresh weight as one-, two- and three-dimensional characteristics values, respectively. The q(e) value from the cell concentration (q(e1D)) obtained was 13.5 × 10⁻⁸ μE cell⁻¹ s⁻¹, and the maximum astaxanthin concentration was increased to 150 % compared to that of a control with constant light intensity. The other optimum q e values by cell projection area (q(e2D)) and fresh weight (q( e3D)) were determined to be 195 μE m⁻² s⁻¹ and 10.5 μE g⁻¹ s⁻¹ for astaxanthin production, respectively. The maximum astaxanthin production from the lumostatic cultures using the parameters controlled by cell projection area (2D) and fresh weight (3D) also increased by 36 and 22% over that of the controls, respectively. When comparing the optimal q e values among the three different types, the lumostatic cultures using q(e) based on fresh weight showed the highest astaxanthin productivity (22.8 mg L⁻¹ day⁻¹), which was a higher level than previously reported. The lumostatic operations reported here demonstrated that more efficient and effective astaxanthin production was obtained by H. lacustris than providing a constant light intensity, regardless of which parameter is used to calculate the specific light uptake rate.

High temperature stimulates acetic acid accumulation and enhances the growth inhibition and ethanol production by Saccharomyces cerevisiae under fermenting conditions.

PubMed

Woo, Ji-Min; Yang, Kyung-Mi; Kim, Sae-Um; Blank, Lars M; Park, Jin-Byung

2014-07-01

Cellular responses of Saccharomyces cerevisiae to high temperatures of up to 42 °C during ethanol fermentation at a high glucose concentration (i.e., 100 g/L) were investigated. Increased temperature correlated with stimulated glucose uptake to produce not only the thermal protectant glycerol but also ethanol and acetic acid. Carbon flux into the tricarboxylic acid (TCA) cycle correlated positively with cultivation temperature. These results indicate that the increased demand for energy (in the form of ATP), most likely caused by multiple stressors, including heat, acetic acid, and ethanol, was matched by both the fermentation and respiration pathways. Notably, acetic acid production was substantially stimulated compared to that of other metabolites during growth at increased temperature. The acetic acid produced in addition to ethanol seemed to subsequently result in adverse effects, leading to increased production of reactive oxygen species. This, in turn, appeared to cause the specific growth rate, and glucose uptake rate reduced leading to a decrease of the specific ethanol production rate far before glucose depletion. These results suggest that adverse effects from heat, acetic acid, ethanol, and oxidative stressors are synergistic, resulting in a decrease of the specific growth rate and ethanol production rate and, hence, are major determinants of cell stability and ethanol fermentation performance of S. cerevisiae at high temperatures. The results are discussed in the context of possible applications.

Assessing the Role of Dissolved Organic Phosphate on Rates of Microbial Phosphorus Cycling

NASA Astrophysics Data System (ADS)

Gonzalez, A. C.; Popendorf, K. J.; Duhamel, S.

2016-02-01

Phosphorus (P) is an element crucial to life, and it is limiting in many parts of the ocean. In oligotrophic environments, the dissolved P pool is cycled rapidly through the activity of microbes, with turnover times of several hours or less. The overarching aim of this study was to assess the flux of P from picoplankton to the dissolved pool and the role this plays in fueling rapid P cycling. To determine if specific microbial groups are responsible for significant return of P to the dissolved pool during cell lifetime, we compared the rate of cellular P turnover (cell-Pτ, the rate of cellular P uptake divided by cellular P content) to the rate of cellular biomass turnover (cellτ). High rates of P return to the dissolved pool during cell lifetime (high cell-Pτ/cellτ) indicate significant P regeneration, fueling more rapid turnover of the dissolved P pool. We hypothesized that cell-Pτ/cellτ varies widely across picoplankton groups. One factor influencing this variation may be each microbial group's relative uptake of dissolved organic phosphorus (DOP) versus dissolved inorganic phosphorus (DIP). As extracellular hydrolysis is necessary for P incorporation from DOP, this process may return more P to the dissolved pool than DIP incorporation. This leads to the question: does a picoplankton's relative uptake of DOP (versus DIP) affect the rate at which it returns phosphorus to the dissolved pool? To address this question, we compared the rate of cellular P turnover based on uptake of DOP and uptake DIP using cultured representatives of three environmentally significant picoplankton groups: Prochlorococcus, Synechococcus, and heterotrophic bacteria. These different picoplankton groups are known to take up different ratios of DOP to DIP, and may in turn make significantly different contributions to the regeneration and cycling phosphorus. These findings have implications towards our understanding of the timeframes of biogeochemical cycling of phosphorus in the ocean.

Race-specific trends in HPV vaccinations and provider recommendations: persistent disparities or social progress?

PubMed

Burdette, Amy M; Webb, Noah S; Hill, Terrence D; Jokinen-Gordon, Hanna

2017-01-01

Although racial and ethnic differences in HPV vaccination initiation are well established, it is unclear whether these disparities have changed over time. The role of health provider recommendations in reducing any racial and ethnic inequalities is also uncertain. This study addresses these gaps in the literature. Repeated cross-sectional design. Using data from the National Immunization Survey-Teen (2008-2013), we estimated a series of binary logistic regressions to model race-specific trends in (1) provider recommendations to vaccinate against HPV and (2) HPV vaccine initiation for males (n = 56,632) and females (n = 77,389). Provider recommendations to vaccinate and HPV vaccination uptake have increased over time for adolescent males and females and across all racial and ethnic groups. Among girls, minority youths have seen a sharper increase in provider recommendations and HPV vaccination uptake than their White counterparts. Among boys, minority teens maintain higher overall rates of HPV vaccine uptake, however, Hispanics have lagged behind non-Hispanic Whites in the rate of increase in provider recommendations and HPV vaccinations. Our results suggest that racial and ethnic disparities in provider recommendations and HPV vaccinations have waned over time among males and females. While these trends are welcomed, additional interventions are warranted to increase overall rates of vaccination across race, ethnicity, and gender. Copyright © 2016 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Nitrogen dioxide (NO2) uptake by vegetation controlled by atmospheric concentrations and plant stomatal aperture

NASA Astrophysics Data System (ADS)

Chaparro-Suarez, I. G.; Meixner, F. X.; Kesselmeier, J.

2011-10-01

Nitrogen dioxide (NO2) exchange between the atmosphere and five European tree species was investigated in the laboratory using a dynamic branch enclosure system (consisting of two cuvettes) and a highly specific NO2 analyzer. NO2 measurements were performed with a sensitive gas phase chemiluminescence NO detector combined with a NO2 specific (photolytic) converter, both from Eco-Physics (Switzerland). This highly specific detection system excluded bias from other nitrogen compounds. Investigations were performed at two light intensities (Photosynthetic Active Radiation, PAR, 450 and 900 μmol m-2 s-1) and NO2 concentrations between 0 and 5 ppb. Ambient parameters (air temperature and relative humidity) were held constant. The data showed dominant NO2 uptake by the respective tree species under all conditions. The results did not confirm the existence of a compensation point within a 95% confidence level, though we cannot completely exclude emission of NO2 under very low atmospheric concentrations. Induced stomatal stricture, or total closure, by changing light conditions, as well as by application of the plant hormone ABA (Abscisic Acid) caused a corresponding decrease of NO2 uptake. No loss of NO2 to plant surfaces was observed under stomatal closure and species dependent differences in uptake rates could be clearly related to stomatal behavior.

Estimation of time-varying growth, uptake and excretion rates from dynamic metabolomics data.

PubMed

Cinquemani, Eugenio; Laroute, Valérie; Cocaign-Bousquet, Muriel; de Jong, Hidde; Ropers, Delphine

2017-07-15

Technological advances in metabolomics have made it possible to monitor the concentration of extracellular metabolites over time. From these data, it is possible to compute the rates of uptake and excretion of the metabolites by a growing cell population, providing precious information on the functioning of intracellular metabolism. The computation of the rate of these exchange reactions, however, is difficult to achieve in practice for a number of reasons, notably noisy measurements, correlations between the concentration profiles of the different extracellular metabolites, and discontinuties in the profiles due to sudden changes in metabolic regime. We present a method for precisely estimating time-varying uptake and excretion rates from time-series measurements of extracellular metabolite concentrations, specifically addressing all of the above issues. The estimation problem is formulated in a regularized Bayesian framework and solved by a combination of extended Kalman filtering and smoothing. The method is shown to improve upon methods based on spline smoothing of the data. Moreover, when applied to two actual datasets, the method recovers known features of overflow metabolism in Escherichia coli and Lactococcus lactis , and provides evidence for acetate uptake by L. lactis after glucose exhaustion. The results raise interesting perspectives for further work on rate estimation from measurements of intracellular metabolites. The Matlab code for the estimation method is available for download at https://team.inria.fr/ibis/rate-estimation-software/ , together with the datasets. eugenio.cinquemani@inria.fr. Supplementary data are available at Bioinformatics online. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

Delivery Rate Affects Uptake of a Fluorescent Glucose Analog in Murine Metastatic Breast Cancer

PubMed Central

Rajaram, Narasimhan; Frees, Amy E.; Fontanella, Andrew N.; Zhong, Jim; Hansen, Katherine; Dewhirst, Mark W.; Ramanujam, Nirmala

2013-01-01

We demonstrate an optical strategy using intravital microscopy of dorsal skin flap window chamber models to image glucose uptake and vascular oxygenation in vivo. Glucose uptake was imaged using a fluorescent glucose analog, 2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl)amino]-2-deoxyglucose (2-NBDG). SO2 was imaged using the differential absorption properties of oxygenated [HbO2] and deoxygenated hemoglobin [dHb]. This study was carried out on two sibling murine mammary adenocarcinoma lines, 4T1 and 4T07. 2-NBDG uptake in the 4T1 tumors was lowest when rates of delivery and clearance were lowest, indicating perfusion-limited uptake in poorly oxygenated tumor regions. For increasing rates of delivery that were still lower than the glucose consumption rate (as measured in vitro), both 2-NBDG uptake and the clearance rate from the tumor increased. When the rate of delivery of 2-NBDG exceeded the glucose consumption rate, 2-NBDG uptake decreased with any further increase in rate of delivery, but the clearance rate continued to increase. This inflection point was not observed in the 4T07 tumors due to an absence of low delivery rates close to the glucose consumption rate. In the 4T07 tumors, 2-NBDG uptake increased with increasing rates of delivery at low rates of clearance. Our results demonstrate that 2-NBDG uptake in tumors is influenced by the rates of delivery and clearance of the tracer. The rates of delivery and clearance are, in turn, dependent on vascular oxygenation of the tumors. Knowledge of the kinetics of tracer uptake as well as vascular oxygenation is essential to make an informed assessment of glucose demand of a tumor. PMID:24204635

Needle age and season influence photosynthetic temperature response and total annual carbon uptake in mature Picea mariana trees

PubMed Central

Jensen, Anna M.; Warren, Jeffrey M.; Hanson, Paul J.; Childs, Joanne; Wullschleger, Stan D.

2015-01-01

Background and Aims The carbon (C) balance of boreal terrestrial ecosystems is sensitive to increasing temperature, but the direction and thresholds of responses are uncertain. Annual C uptake in Picea and other evergreen boreal conifers is dependent on seasonal- and cohort-specific photosynthetic and respiratory temperature response functions, so this study examined the physiological significance of maintaining multiple foliar cohorts for Picea mariana trees within an ombrotrophic bog ecosystem in Minnesota, USA. Methods Measurements were taken on multiple cohorts of needles for photosynthetic capacity, foliar respiration (Rd) and leaf biochemistry and morphology of mature trees from April to October over 4 years. The results were applied to a simple model of canopy photosynthesis in order to simulate annual C uptake by cohort age under ambient and elevated temperature scenarios. Key Results Temperature responses of key photosynthetic parameters [i.e. light-saturated rate of CO2 assimilation (Asat), rate of Rubisco carboxylation (Vcmax) and electron transport rate (Jmax)] were dependent on season and generally less responsive in the developing current-year (Y0) needles compared with 1-year-old (Y1) or 2-year-old (Y2) foliage. Temperature optimums ranged from 18·7 to 23·7, 31·3 to 38·3 and 28·7 to 36·7 °C for Asat, Vcmax and Jmax, respectively. Foliar cohorts differed in their morphology and photosynthetic capacity, which resulted in 64 % of modelled annual stand C uptake from Y1&2 cohorts (LAI 0·67 m2 m−2) and just 36 % from Y0 cohorts (LAI 0·52 m2 m−2). Under warmer climate change scenarios, the contribution of Y0 cohorts was even less; e.g. 31 % of annual C uptake for a modelled 9 °C rise in mean summer temperatures. Results suggest that net annual C uptake by P. mariana could increase under elevated temperature, and become more dependent on older foliar cohorts. Conclusions Collectively, this study illustrates the physiological and ecological significance of different foliar cohorts, and indicates the need for seasonal- and cohort-specific model parameterization when estimating C uptake capacity of boreal forest ecosystems under ambient or future temperature scenarios. PMID:26220656

Alexandrium minutum growth controlled by phosphorus . An applied model

NASA Astrophysics Data System (ADS)

Chapelle, A.; Labry, C.; Sourisseau, M.; Lebreton, C.; Youenou, A.; Crassous, M. P.

2010-11-01

Toxic algae are a worldwide problem threatening aquaculture, public health and tourism. Alexandrium, a toxic dinoflagellate proliferates in Northwest France estuaries (i.e. the Penzé estuary) causing Paralytic Shellfish Poisoning events. Vegetative growth, and in particular the role of nutrient uptake and growth rate, are crucial parameters to understand toxic blooms. With the goal of modelling in situ Alexandrium blooms related to environmental parameters, we first try to calibrate a zero-dimensional box model of Alexandrium growth. This work focuses on phosphorus nutrition. Our objective is to calibrate Alexandrium minutum as well as Heterocapsa triquetra (a non-toxic dinoflagellate) growth under different rates of phosphorus supply, other factors being optimal and constant. Laboratory experiments are used to calibrate two growth models and three uptake models for each species. Models are then used to simulate monospecific batch and semi-continuous experiments as well as competition between the two algae (mixed cultures). Results show that the Droop growth model together with linear uptake versus quota can represent most of our observations, although a power law uptake function can more accurately simulate our phosphorus uptake data. We note that such models have limitations in non steady-state situations and cell quotas can depend on a variety of factors, so care must be taken in extrapolating these results beyond the specific conditions studied.

Lrp5 Has a Wnt-Independent Role in Glucose Uptake and Growth for Mammary Epithelial Cells

PubMed Central

Chin, Emily N.; Martin, Joshua A.; Kim, Soyoung; Fakhraldeen, Saja A.

2015-01-01

Lrp5 is typically described as a Wnt signaling receptor, albeit a less effective Wnt signaling receptor than the better-studied sister isoform, Lrp6. Here we show that Lrp5 is only a minor player in the response to Wnt3a-type ligands in mammary epithelial cells; instead, Lrp5 is required for glucose uptake, and glucose uptake regulates the growth rate of mammary epithelial cells in culture. Thus, a loss of Lrp5 leads to profound growth suppression, whether growth is induced by serum or by specific growth factors, and this inhibition is not due to a loss of Wnt signaling. Depletion of Lrp5 decreases glucose uptake, lactate secretion, and oxygen consumption rates; inhibition of glucose consumption phenocopies the loss of Lrp5 function. Both Lrp5 knockdown and low external glucose induce mitochondrial stress, as revealed by the accumulation of reactive oxygen species (ROS) and the activation of the ROS-sensitive checkpoint, p38α. In contrast, loss of function of Lrp6 reduces Wnt responsiveness but has little impact on growth. This highlights the distinct functions of these two Lrp receptors and an important Wnt ligand-independent role of Lrp5 in glucose uptake in mammary epithelial cells. PMID:26711269

Specific physiological and biomechanical performance in elite, sub-elite and in non-elite male team handball players.

PubMed

Wagner, Herbert; Fuchs, Philip X; von Duvillard, Serge P

2018-01-01

Team handball is a dynamic sport game that is played professionally in numerous countries. However, knowledge about training and competition is based mostly on practical experience due to limited scientific studies. Consequently, the aims of our study were to compare specific physiological and biomechanical performance in elite, sub-elite and in non-elite male team handball players. Thirty-six elite, sub-elite and non-elite male team handball players performed a game based performance test, upper-body and lower-body strength tests, 30-m sprint test, counter movement jump test and an incremental treadmill running test. Significant differences (P<0.05) were found for the peak oxygen uptake, heart rate, offense and defense time, jump height and ball velocity during the jump throw in the game based performance test, maximal oxygen uptake in the incremental treadmill running test as well as in maximal leg strength and leg explosive strength in the isometric strength test. Elite male players have an enhanced specific agility, a better throwing performance, a higher team handball specific oxygen uptake and higher leg strength compared to sub-elite and non-elite players. Based on these results we recommend that training in team handball should focus on game based training methods to improve performance in specific agility, endurance and technique.

Effects of CO(2) enrichment on photosynthesis, growth, and nitrogen metabolism of the seagrass Zostera noltii.

PubMed

Alexandre, Ana; Silva, João; Buapet, Pimchanok; Björk, Mats; Santos, Rui

2012-10-01

Seagrass ecosystems are expected to benefit from the global increase in CO(2) in the ocean because the photosynthetic rate of these plants may be C(i)-limited at the current CO(2) level. As well, it is expected that lower external pH will facilitate the nitrate uptake of seagrasses if nitrate is cotransported with H(+) across the membrane as in terrestrial plants. Here, we investigate the effects of CO(2) enrichment on both carbon and nitrogen metabolism of the seagrass Zostera noltii in a mesocosm experiment where plants were exposed for 5 months to two experimental CO(2) concentrations (360 and 700 ppm). Both the maximum photosynthetic rate (P(m)) and photosynthetic efficiency (α) were higher (1.3- and 4.1-fold, respectively) in plants exposed to CO(2)-enriched conditions. On the other hand, no significant effects of CO(2) enrichment on leaf growth rates were observed, probably due to nitrogen limitation as revealed by the low nitrogen content of leaves. The leaf ammonium uptake rate and glutamine synthetase activity were not significantly affected by increased CO(2) concentrations. On the other hand, the leaf nitrate uptake rate of plants exposed to CO(2)-enriched conditions was fourfold lower than the uptake of plants exposed to current CO(2) level, suggesting that in the seagrass Z. noltii nitrate is not cotransported with H(+) as in terrestrial plants. In contrast, the activity of nitrate reductase was threefold higher in plant leaves grown at high-CO(2) concentrations. Our results suggest that the global effects of CO(2) on seagrass production may be spatially heterogeneous and depend on the specific nitrogen availability of each system. Under a CO(2) increase scenario, the natural levels of nutrients will probably become limiting for Z. noltii. This potential limitation becomes more relevant because the expected positive effect of CO(2) increase on nitrate uptake rate was not confirmed.

Effects of CO2 enrichment on photosynthesis, growth, and nitrogen metabolism of the seagrass Zostera noltii

PubMed Central

Alexandre, Ana; Silva, João; Buapet, Pimchanok; Björk, Mats; Santos, Rui

2012-01-01

Seagrass ecosystems are expected to benefit from the global increase in CO2 in the ocean because the photosynthetic rate of these plants may be Ci-limited at the current CO2 level. As well, it is expected that lower external pH will facilitate the nitrate uptake of seagrasses if nitrate is cotransported with H+ across the membrane as in terrestrial plants. Here, we investigate the effects of CO2 enrichment on both carbon and nitrogen metabolism of the seagrass Zostera noltii in a mesocosm experiment where plants were exposed for 5 months to two experimental CO2 concentrations (360 and 700 ppm). Both the maximum photosynthetic rate (Pm) and photosynthetic efficiency (α) were higher (1.3- and 4.1-fold, respectively) in plants exposed to CO2-enriched conditions. On the other hand, no significant effects of CO2 enrichment on leaf growth rates were observed, probably due to nitrogen limitation as revealed by the low nitrogen content of leaves. The leaf ammonium uptake rate and glutamine synthetase activity were not significantly affected by increased CO2 concentrations. On the other hand, the leaf nitrate uptake rate of plants exposed to CO2-enriched conditions was fourfold lower than the uptake of plants exposed to current CO2 level, suggesting that in the seagrass Z. noltii nitrate is not cotransported with H+ as in terrestrial plants. In contrast, the activity of nitrate reductase was threefold higher in plant leaves grown at high-CO2 concentrations. Our results suggest that the global effects of CO2 on seagrass production may be spatially heterogeneous and depend on the specific nitrogen availability of each system. Under a CO2 increase scenario, the natural levels of nutrients will probably become limiting for Z. noltii. This potential limitation becomes more relevant because the expected positive effect of CO2 increase on nitrate uptake rate was not confirmed. PMID:23145346

Growth of the extremophilic Deinococcus geothermalis DSM 11302 using co-substrate fed-batch culture.

PubMed

Bornot, Julie; Molina-Jouve, Carole; Uribelarrea, Jean-Louis; Gorret, Nathalie

2014-02-01

Deinococcus geothermalis metabolism has been scarcely studied to date, although new developments on its utilization for bioremediation have been carried out. So, large-scale production of this strain and a better understanding of its physiology are required. A fed-batch experiment was conducted to achieve a high cell density non-limiting culture of D. geothermalis DSM 11302. A co-substrate nutritional strategy using glucose and yeast extract was carried out in a 20-L bioreactor in order to maintain a non-limited growth at a maximal growth rate of 1 h(-1) at 45 °C. Substrate supplies were adjusted by monitoring online culture parameters and physiological data (dissolved oxygen, gas analyses, respiratory quotient, biomass concentration). The results showed that yeast extract could serve as both carbon and nitrogen sources, although glucose and ammonia were consumed too. Yeast extract carbon-specific uptake rate reached a value 4.5 times higher than glucose carbon-specific uptake rate. Cell concentration of 9.6 g L(-1) dry cell weight corresponding to 99 g of biomass was obtained using glucose and yeast extract as carbon and nitrogen sources.

Ethanol production improvement driven by genome-scale metabolic modeling and sensitivity analysis in Scheffersomyces stipitis

PubMed Central

2017-01-01

The yeast Scheffersomyces stipitis naturally produces ethanol from xylose, however reaching high ethanol yields is strongly dependent on aeration conditions. It has been reported that changes in the availability of NAD(H/+) cofactors can improve fermentation in some microorganisms. In this work genome-scale metabolic modeling and phenotypic phase plane analysis were used to characterize metabolic response on a range of uptake rates. Sensitivity analysis was used to assess the effect of ARC on ethanol production indicating that modifying ARC by inhibiting the respiratory chain ethanol production can be improved. It was shown experimentally in batch culture using Rotenone as an inhibitor of the mitochondrial NADH dehydrogenase complex I (CINADH), increasing ethanol yield by 18%. Furthermore, trajectories for uptakes rates, specific productivity and specific growth rate were determined by modeling the batch culture, to calculate ARC associated to the addition of CINADH inhibitor. Results showed that the increment in ethanol production via respiratory inhibition is due to excess in ARC, which generates an increase in ethanol production. Thus ethanol production improvement could be predicted by a change in ARC. PMID:28658270

Ethanol production improvement driven by genome-scale metabolic modeling and sensitivity analysis in Scheffersomyces stipitis.

PubMed

Acevedo, Alejandro; Conejeros, Raúl; Aroca, Germán

2017-01-01

The yeast Scheffersomyces stipitis naturally produces ethanol from xylose, however reaching high ethanol yields is strongly dependent on aeration conditions. It has been reported that changes in the availability of NAD(H/+) cofactors can improve fermentation in some microorganisms. In this work genome-scale metabolic modeling and phenotypic phase plane analysis were used to characterize metabolic response on a range of uptake rates. Sensitivity analysis was used to assess the effect of ARC on ethanol production indicating that modifying ARC by inhibiting the respiratory chain ethanol production can be improved. It was shown experimentally in batch culture using Rotenone as an inhibitor of the mitochondrial NADH dehydrogenase complex I (CINADH), increasing ethanol yield by 18%. Furthermore, trajectories for uptakes rates, specific productivity and specific growth rate were determined by modeling the batch culture, to calculate ARC associated to the addition of CINADH inhibitor. Results showed that the increment in ethanol production via respiratory inhibition is due to excess in ARC, which generates an increase in ethanol production. Thus ethanol production improvement could be predicted by a change in ARC.

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.

Unravelling evolutionary strategies of yeast for improving galactose utilization through integrated systems level analysis.

PubMed

Hong, Kuk-Ki; Vongsangnak, Wanwipa; Vemuri, Goutham N; Nielsen, Jens

2011-07-19

Identification of the underlying molecular mechanisms for a derived phenotype by adaptive evolution is difficult. Here, we performed a systems-level inquiry into the metabolic changes occurring in the yeast Saccharomyces cerevisiae as a result of its adaptive evolution to increase its specific growth rate on galactose and related these changes to the acquired phenotypic properties. Three evolved mutants (62A, 62B, and 62C) with higher specific growth rates and faster specific galactose uptake were isolated. The evolved mutants were compared with a reference strain and two engineered strains, SO16 and PGM2, which also showed higher galactose uptake rate in previous studies. The profile of intermediates in galactose metabolism was similar in evolved and engineered mutants, whereas reserve carbohydrates metabolism was specifically elevated in the evolved mutants and one evolved strain showed changes in ergosterol biosynthesis. Mutations were identified in proteins involved in the global carbon sensing Ras/PKA pathway, which is known to regulate the reserve carbohydrates metabolism. We evaluated one of the identified mutations, RAS2(Tyr112), and this mutation resulted in an increased specific growth rate on galactose. These results show that adaptive evolution results in the utilization of unpredicted routes to accommodate increased galactose flux in contrast to rationally engineered strains. Our study demonstrates that adaptive evolution represents a valuable alternative to rational design in bioengineering of improved strains and, that through systems biology, it is possible to identify mutations in evolved strain that can serve as unforeseen metabolic engineering targets for improving microbial strains for production of biofuels and chemicals.

Nitrogen fluxes at the root-soil interface show a mismatch of nitrogen fertilizer supply and sugarcane root uptake capacity

NASA Astrophysics Data System (ADS)

Inselsbacher, Erich; Schmidt, Susanne; Näsholm, Torgny; Robinson, Nicole; Guillou, Stéphane; Vinall, Kerry; Lakshmanan, Prakash; Brackin, Richard

2016-04-01

Nitrogen (N) uptake by agricultural crops is a key constituent of the global N cycle, as N captured by roots has a markedly different fate than N remaining in the soil. Global evidence indicates that only approximately 50% of applied N fertilizer is captured by crops, and the remainder can cause pollution via runoff and gaseous emissions. This inefficiency is of global concern, and requires innovation based on improved understanding of which N forms are available for and ultimately taken up by crops. However, current soil analysis methods based on destructive soil sampling provide little insight into delivery and acquisition of N forms by roots. Here, we present the results of a study in sugarcane fields receiving different fertilizer regimes comparing soil N supply rates with potential root N uptake rates. We applied microdialysis, a novel technique for in situ quantification of soil nutrient fluxes, to measure flux rates of inorganic N and amino acid N, and analyzed N uptake capacities of sugarcane roots using 15N labelled tracers. We found that in fertilized sugarcane soils, fluxes of inorganic N exceed the uptake capacities of sugarcane roots by several orders of magnitude. Contrary, fluxes of organic N closely matched roots' uptake capacity. These results indicate root uptake capacity constrains plant acquisition of inorganic N. This mismatch between soil N supply and root N uptake capacity is a likely key driver for low N efficiency in the studied crop system. Our results also suggest that the relative contribution of inorganic N for plant nutrition may be overestimated when relying on soil extracts as indicators for root-available N, and organic N may contribute more to crop N supply than is currently assumed. Overall, we show a new approach for examining in situ N relations in soil in context of crop N physiology, which provides a new avenue towards tailoring N fertilizer supply to match the specific uptake abilities and N demand of crops over the growth cycle.

Nitrogen cycling process rates across urban ecosystems.

PubMed

Reisinger, Alexander J; Groffman, Peter M; Rosi-Marshall, Emma J

2016-09-21

Nitrogen (N) pollution of freshwater, estuarine, and marine ecosystems is widespread and has numerous environmental and economic impacts. A portion of this excess N comes from urban watersheds comprised of natural and engineered ecosystems which can alter downstream N export. Studies of urban N cycling have focused on either specific ecosystems or on watershed-scale mass balances. Comparisons of specific N transformations across ecosystems are required to contextualize rates from individual studies. Here we reviewed urban N cycling in terrestrial, aquatic, and engineered ecosystems, and compared N processing in these urban ecosystem types to native reference ecosystems. We found that net N mineralization and net nitrification rates were enhanced in urban forests and riparian zones relative to reference ecosystems. Denitrification was highly variable across urban ecosystem types, but no significant differences were found between urban and reference denitrification rates. When focusing on urban streams, ammonium uptake was more rapid than nitrate uptake in urban streams. Additionally, reduction of stormwater runoff coupled with potential decreases in N concentration suggests that green infrastructure may reduce downstream N export. Despite multiple environmental stressors in urban environments, ecosystems within urban watersheds can process and transform N at rates similar to or higher than reference ecosystems. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Coupling of methylmercury uptake with respiration and water pumping in freshwater tilapia Oreochromis niloticus.

PubMed

Wang, Rui; Wong, Ming-Hung; Wang, Wen-Xiong

2011-09-01

The relationships among the uptake of toxic methylmercury (MeHg) and two important fish physiological processes-respiration and water pumping--in the Nile tilapia (Oreochromis niloticus) were explored in the present study. Coupled radiotracer and respirometric techniques were applied to measure simultaneously the uptake rates of MeHg, water, and oxygen under various environmental conditions (temperature, dissolved oxygen level, and water flow). A higher temperature enhanced MeHg influx and the oxygen consumption rate but had no effect on the water uptake, indicating the influence of metabolism on MeHg uptake. The fish showed a high tolerance to hypoxia, and the oxygen consumption rate was not affected until the dissolved oxygen concentration decreased to extremely low levels (below 1 mg/L). The MeHg and water uptake rates increased simultaneously as the dissolved oxygen level decreased, suggesting the coupling of water flux and MeHg uptake. The influence of fish swimming performance on MeHg uptake was also investigated for the first time. Rapidly swimming fish showed significantly higher uptake rates of MeHg, water, and oxygen, confirming the coupling relationships among respiration, water pumping, and metal uptake. Moreover, these results support that MeHg uptake is a rate-limiting process involving energy. Our study demonstrates the importance of physiological processes in understanding mercury bioaccumulation in fluctuating aquatic environments. Copyright © 2011 SETAC.

[Effects of carbon sources, temperature and electron acceptors on biological phosphorus removal].

PubMed

Han, Yun; Xu, Song; Dong, Tao; Wang, Bin-Fan; Wang, Xian-Yao; Peng, Dang-Cong

2015-02-01

Effects of carbon sources, temperature and electron acceptors on phosphorus uptake and release were investigated in a pilot-scale oxidation ditch. Phosphorus uptake and release rates were measured with different carbon sources (domestic sewage, sodium acetate, glucose) at 25 degrees C. The results showed that the minimum phosphorus uptake and release rates of glucose were 5.12 mg x (g x h)(-1) and 6.43 mg x (g x h)(-1), respectively, and those of domestic sewage are similar to those of sodium acetate. Phosphorus uptake and release rates increased with the increase of temperature (12, 16, 20 and 25 degrees C) using sodium acetate as carbon sources. Anoxic phosphorus uptake rate decreased with added COD. Electron acceptors (oxygen, nitrate, nitrite) had significant effects on phosphorus uptake rate and their order was in accordance with oxygen > nitrate > nitrite. The mass ratio of anoxic P uptake and N consumption (P(uptake)/N (consumption)) of nitrate and nitrite were 0.96 and 0.65, respectively.

Effect of Tumor Microenvironment on Selective Uptake of Boric Acid in HepG2 Human Hepatoma Cells.

PubMed

Bai, Yu-Chi; Hsia, Yu-Chun; Lin, Yu-Ting; Chen, Kuan-Hao; Chou, Fong-In; Yang, Chia-Min; Chuang, Yung-Jen

2017-11-01

Feasibility and efficacy of boric acid (BA)-mediated boron neutron capture therapy (BNCT) was first demonstrated by eliminating hepatocellular carcinoma (HCC) in a rat model. Furthermore, selective uptake of BA by liver tumor cells was shown in a rabbit model. To gain further insight, this study aimed to investigate the mechanisms of transportation and selective uptake of BA in HepG2 liver tumor cells. Transportation of BA in HepG2 cells was analyzed by time-course assays and by analyzing the rate of diffusion versus the concentration of BA. The effect of different tumor conditions on BA uptake was studied by treating HepG2 cells with 25 μg 10 B/ml BA under different concentrations of glucose, at different pH and in the presence of water-soluble cholesterol. HepG2 cells mainly uptake BA by simple diffusion. Cell membrane permeability may also contribute to tumor-specific uptake of BA. The selective uptake of BA was achieved primarily by diffusion, while other factors, such as low pH and increased membrane fluidity, which are hallmarks of HCC, might further enhance BA uptake. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

The contribution of water soluble and water insoluble organic fractions to oxygen uptake rate during high rate composting.

PubMed

Giuliana, D'Imporzano; Fabrizio, Adani

2007-02-01

This study aims to establish the contribution of the water soluble and water insoluble organic fractions to total oxygen uptake rate during high rate composting process of a mixture of organic fraction of municipal solid waste and lignocellulosic material. This mixture was composted using a 20 l self-heating pilot scale composter for 250 h. The composter was fully equipped to record both the biomass-temperature and oxygen uptake rate. Representative compost samples were taken at 0, 70, 100, 110, 160, and 250 h from starting time. Compost samples were fractionated in water soluble and water insoluble fractions. The water soluble fraction was then fractionated in hydrophilic, hydrophobic, and neutral hydrophobic fractions. Each fraction was then studied using quantitative (total organic carbon) and qualitative analysis (diffuse reflectance infrared spectroscopy and biodegradability test). Oxygen uptake rates were high during the initial stages of the process due to rapid degradation of the soluble degradable organic fraction (hydrophilic plus hydrophobic fractions). Once this fraction was depleted, polymer hydrolysis accounted for most of the oxygen uptake rate. Finally, oxygen uptake rate could be modeled using a two term kinetic. The first term provides the oxygen uptake rate resulting from the microbial growth kinetic type on easily available, no-limiting substrate (soluble fraction), while the second term considers the oxygen uptake rate caused by the degradation of substrate produced by polymer hydrolysis.

Evaluation of Populus and Salix continuously irrigated with landfill leachate I. Genotype-specific elemental phytoremediation

Treesearch

Ronald S., Jr. Zalesny; Edmund O. Bauer

2007-01-01

There is a need for the identification and selection of specific tree genotypes that can sequester elements from contaminated soils, with elevated rates of uptake. We irrigated Populus (DN17, DN182, DN34, NM2, NM6) and Salix (94003, 94012, S287, S566, SX61) genotypes planted in large soil-filled containers with landfill leachate or...

Estimated dose rates to members of the public from external exposure to patients with 131I thyroid treatment

DOE PAGES

Dewji, S.; Bellamy, M.; Hertel, N.; ...

2015-03-25

The purpose of this study is to estimate dose rates that may result from exposure to patients who had been administered iodine-131 ( 131I) as part of medical therapy were calculated. These effective dose rate estimates were compared with simplified assumptions under United States Nuclear Regulatory Commission Regulatory Guide 8.39, which does not consider body tissue attenuation nor time-dependent redistribution and excretion of the administered 131I. Methods: Dose rates were estimated for members of the public potentially exposed to external irradiation from patients recently treated with 131I. Tissue attenuation and iodine biokinetics were considered in the patient in a largermore » comprehensive effort to improve external dose rate estimates. The external dose rate estimates are based on Monte Carlo simulations using the Phantom with Movable Arms and Legs (PIMAL), previously developed by Oak Ridge National Laboratory and the United States Nuclear Regulatory Commission. PIMAL was employed to model the relative positions of the 131I patient and members of the public in three exposure scenarios: (1) traveling on a bus in a total of six seated or standing permutations, (2) two nursing home cases where a caregiver is seated at 30 cm from the patient’s bedside and a nursing home resident seated 250 cm away from the patient in an adjacent bed, and (3) two hotel cases where the patient and a guest are in adjacent rooms with beds on opposite sides of the common wall, with the patient and guest both in bed and either seated back-to-back or lying head to head. The biokinetic model predictions of the retention and distribution of 131I in the patient assumed a single voiding of urinary bladder contents that occurred during the trip at 2, 4, or 8 h after 131I administration for the public transportation cases, continuous first-order voiding for the nursing home cases, and regular periodic voiding at 4, 8, or 12 h after administration for the hotel room cases. Organ specific activities of 131I in the thyroid, bladder, and combined remaining tissues were calculated as a function of time after administration. Exposures to members of the public were considered for 131I patients with normal thyroid uptake (peak thyroid uptake of ~27% of administered 131I), differentiated thyroid cancer (DTC, 5% uptake), and hyperthyroidism (80% uptake). Results: The scenario with the patient seated behind the member of the public yielded the highest dose rate estimate of seated public transportation exposure cases. The dose rate to the adjacent room guest was highest for the exposure scenario in which the hotel guest and patient are seated by a factor of ~4 for the normal and differentiated thyroid cancer uptake cases and by a factor of ~3 for the hyperthyroid case. Conclusions: It was determined that for all modeled cases, the DTC case yielded the lowest external dose rates, whereas the hyperthyroid case yielded the highest dose rates. In estimating external dose to members of the public from patients with 131I therapy, consideration must be given to (patient- and case-specific) administered 131I activities and duration of exposure for a more complete estimate. The method implemented here included a detailed calculation model, which provides a means to determine dose rate estimates for a range of scenarios. Finally, the method was demonstrated for variations of three scenarios, showing how dose rates are expected to vary with uptake, voiding pattern, and patient location.« less

Estimated dose rates to members of the public from external exposure to patients with 131I thyroid treatment

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

Dewji, S.; Bellamy, M.; Hertel, N.

The purpose of this study is to estimate dose rates that may result from exposure to patients who had been administered iodine-131 ( 131I) as part of medical therapy were calculated. These effective dose rate estimates were compared with simplified assumptions under United States Nuclear Regulatory Commission Regulatory Guide 8.39, which does not consider body tissue attenuation nor time-dependent redistribution and excretion of the administered 131I. Methods: Dose rates were estimated for members of the public potentially exposed to external irradiation from patients recently treated with 131I. Tissue attenuation and iodine biokinetics were considered in the patient in a largermore » comprehensive effort to improve external dose rate estimates. The external dose rate estimates are based on Monte Carlo simulations using the Phantom with Movable Arms and Legs (PIMAL), previously developed by Oak Ridge National Laboratory and the United States Nuclear Regulatory Commission. PIMAL was employed to model the relative positions of the 131I patient and members of the public in three exposure scenarios: (1) traveling on a bus in a total of six seated or standing permutations, (2) two nursing home cases where a caregiver is seated at 30 cm from the patient’s bedside and a nursing home resident seated 250 cm away from the patient in an adjacent bed, and (3) two hotel cases where the patient and a guest are in adjacent rooms with beds on opposite sides of the common wall, with the patient and guest both in bed and either seated back-to-back or lying head to head. The biokinetic model predictions of the retention and distribution of 131I in the patient assumed a single voiding of urinary bladder contents that occurred during the trip at 2, 4, or 8 h after 131I administration for the public transportation cases, continuous first-order voiding for the nursing home cases, and regular periodic voiding at 4, 8, or 12 h after administration for the hotel room cases. Organ specific activities of 131I in the thyroid, bladder, and combined remaining tissues were calculated as a function of time after administration. Exposures to members of the public were considered for 131I patients with normal thyroid uptake (peak thyroid uptake of ~27% of administered 131I), differentiated thyroid cancer (DTC, 5% uptake), and hyperthyroidism (80% uptake). Results: The scenario with the patient seated behind the member of the public yielded the highest dose rate estimate of seated public transportation exposure cases. The dose rate to the adjacent room guest was highest for the exposure scenario in which the hotel guest and patient are seated by a factor of ~4 for the normal and differentiated thyroid cancer uptake cases and by a factor of ~3 for the hyperthyroid case. Conclusions: It was determined that for all modeled cases, the DTC case yielded the lowest external dose rates, whereas the hyperthyroid case yielded the highest dose rates. In estimating external dose to members of the public from patients with 131I therapy, consideration must be given to (patient- and case-specific) administered 131I activities and duration of exposure for a more complete estimate. The method implemented here included a detailed calculation model, which provides a means to determine dose rate estimates for a range of scenarios. Finally, the method was demonstrated for variations of three scenarios, showing how dose rates are expected to vary with uptake, voiding pattern, and patient location.« less

Comparison of sarcoplasmic reticulum capabilities in toadfish (Opsanus tau) sonic muscle and rat fast twitch muscle.

PubMed

Feher, J J; Waybright, T D; Fine, M L

1998-08-01

The sonic muscle of the oyster toadfish, Opsanus tau, can produce unfused contractions at 300 Hz. Electron microscopy shows a great abundance of the Sarcoplasmic reticulum (SR) in this muscle, but no functional characterization of the capabilities of the SR has been reported. We measured the oxalate-supported Ca2+ uptake rate and capacities of homogenates of toadfish sonic muscle and rat extensor digitorum longus (EDL) muscle, and estimated the number of pump units by titration with thapsigargin, a high-affinity, specific inhibitor of the SR Ca-ATPase. The Ca2+ uptake rate averaged 70.9 +/- 9.5 mumol min -1 per g tissue for the toad fish sonic muscle, and 73.5 +/- 3.7 mumol min -1 g-1 for rat EDL. The capacity for Ca2+ -oxalate uptake was 161 +/- 20 mumol g -1 and 33 +/- 2 mumol g -1 for toadfish sonic muscle and rat EDL, respectively. Thus, the rates of Ca2+ uptake were similar in the two muscles, but the toadfish sonic muscle had about five times the capacity of the rat EDL. The number of pumps as estimated by thapsigargin titration was 68 +/- 4 nmol of Ca-ATPase per g tissue in the toadfish, and 42 +/- 5 nmol Ca-ATPase per g tissue in the rat EDL. The turnover number, defined as the Ca2+ uptake divided by the number of pumps, was 1065 +/- 150 min -1 for toadfish and 1786 +/- 230 min -1 for rat EDL (p < 0.05) at 37 degrees C. The Ca2+ uptake rate of toadfish sonic muscle at 22 degree C, a typical temperature for calling toadfish, averaged 42 +/- 1% of its rate at 37 degree C. At these operating temperatures, the toadfish SR is likely to be slower than the rat fast-twitch SR, yet the toadfish sonic muscle supports more rapid contractions. One explanation for this is that the voluminous SR provides activator Ca2+ for contraction, but the abundant parvalbumin plays a major role in relaxation.

User’s Guide for Biodegradation Reactions in TMVOCBio

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

Jung, Yoojin; Battistelli, Alfredo

TMVOCBio is an extended version of the TMVOC numerical reservoir simulator, with the capability of simulating multiple biodegradation reactions mediated by different microbial populations or based on different redox reactions, thus involving different electron acceptors. This modeling feature is implemented within the existing TMVOC module in iTOUGH2. TMVOCBio, originally developed by Battistelli (2003; 2004), uses a general modified form of the Monod kinetic rate equation to simulate biodegradation reactions, which effectively simulates the uptake of a substrate while accounting for various limiting factors (i.e., the limitation by substrate, electron acceptor, or nutrients). Two approaches are included: 1) a multiple Monodmore » kinetic rate equation, which assumes all the limiting factors simultaneously affect the substrate uptake rate, and 2) a minimum Monod model, which assumes that the substrate uptake rate is controlled by the most limiting factor among those acting for the specific substrate. As the limiting factors, biomass growth inhibition, toxicity effects, as well as competitive and non-competitive inhibition effects are included. The temperature and moisture dependence of biodegradation reactions is also considered. This report provides mathematical formulations and assumptions used for modeling the biodegradation reactions, and describes additional modeling capabilities. Detailed description of input format for biodegradation reactions is presented along with sample problems.« less

Barriers and Misperceptions Limiting Widespread Use of Intrauterine Contraception Among Canadian Women.

PubMed

Hauck, Brian; Costescu, Dustin

2015-07-01

Unintended pregnancy is a major social and public health problem with adverse effects on neonatal and developmental outcomes, as well as maternal health and wellbeing. Traditionally, family planning policies have focused on increasing contraceptive uptake in non-users; however, rates of non-use are low in many developed nations. A high proportion of unintended pregnancies are attributable to contraceptive failure, particularly when using barrier and short-acting hormonal contraceptives. Intrauterine contraceptive devices (IUCDs) are highly effective and have been shown to reduce unintended pregnancy rates. Despite this, global utilization rates are low, and IUCD uptake in Canada has been particularly low. In this review we explore why IUCDs are not more widely used, and specifically focus on barriers and misperceptions that may influence IUCD uptake, particularly in Canada. We reviewed relevant articles published in English between 1990 and 2014, through searches of PubMed and Medline, including primary studies of any design containing information on the knowledge and attitudes of health care providers and women. Providing education to care providers, women, and policy makers may help overcome misperceptions about the use of IUCDs, and may facilitate greater use. Increased support from federal and provincial health programs may also encourage the use of IUCDs in Canadian women, and help to reduce unintended pregnancy rates.

Temperature Dependence of Inorganic Nitrogen Uptake: Reduced Affinity for Nitrate at Suboptimal Temperatures in Both Algae and Bacteria

PubMed Central

Reay, David S.; Nedwell, David B.; Priddle, Julian; Ellis-Evans, J. Cynan

1999-01-01

Nitrate utilization and ammonium utilization were studied by using three algal isolates, six bacterial isolates, and a range of temperatures in chemostat and batch cultures. We quantified affinities for both substrates by determining specific affinities (specific affinity = maximum growth rate/half-saturation constant) based on estimates of kinetic parameters obtained from chemostat experiments. At suboptimal temperatures, the residual concentrations of nitrate in batch cultures and the steady-state concentrations of nitrate in chemostat cultures both increased. The specific affinity for nitrate was strongly dependent on temperature (Q10 ≈ 3, where Q10 is the proportional change with a 10°C temperature increase) and consistently decreased at temperatures below the optimum temperature. In contrast, the steady-state concentrations of ammonium remained relatively constant over the same temperature range, and the specific affinity for ammonium exhibited no clear temperature dependence. This is the first time that a consistent effect of low temperature on affinity for nitrate has been identified for psychrophilic, mesophilic, and thermophilic bacteria and algae. The different responses of nitrate uptake and ammonium uptake to temperature imply that there is increasing dependence on ammonium as an inorganic nitrogen source at low temperatures. PMID:10347046

Variable phosphorus uptake rates and allocation across microbial groups in the oligotrophic Gulf of Mexico.

PubMed

Popendorf, Kimberly J; Duhamel, Solange

2015-10-01

Microbial uptake of dissolved phosphorus (P) is an important lever in controlling both microbial production and the fate and cycling of marine P. We investigated the relative role of heterotrophic bacteria and phytoplankton in P cycling by measuring the P uptake rates of individual microbial groups (heterotrophic bacteria and the phytoplankton groups Synechococcus, Prochlorococcus and picoeukaryotic phytoplankton) in the P-depleted Gulf of Mexico. Phosphorus uptake rates were measured using incubations with radiolabelled phosphate and adenosine triphosphate coupled with cell sorting flow cytometry. We found that heterotrophic bacteria were the dominant consumers of P on both a biomass basis and a population basis. Biovolume normalized heterotrophic bacteria P uptake rate per cell (amol P μm(-3) h(-1)) was roughly an order of magnitude greater than phytoplankton uptake rates, and heterotrophic bacteria were responsible for generally greater than 50% of total picoplankton P uptake. We hypothesized that this variation in uptake rates reflects variation in cellular P allocation strategies, and found that, indeed, the fraction of cellular P uptake utilized for phospholipid production was significantly higher in heterotrophic bacteria compared with cyanobacterial phytoplankton. These findings indicate that heterotrophic bacteria have a uniquely P-oriented physiology and play a dominant role in cycling dissolved P. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

40 CFR 503.31 - Special definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 503.31 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SEWAGE SLUDGE STANDARDS... microorganisms in the absence of air. (c) Density of microorganisms is the number of microorganisms per unit mass...) Specific oxygen uptake rate (SOUR) is the mass of oxygen consumed per unit time per unit mass of total...

Diurnal changes in net uptake rate of nitrate are associated with changes in estimated export of carbohydrates to roots

NASA Technical Reports Server (NTRS)

Rideout, J. W.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

1994-01-01

The rate of NO3- uptake by soybean (Glycine max [L.] Merrill) roots generally declines during the night in association with progressive depletion of the nonstructural carbohydrate pool in the shoot as well as the concentration of carbohydrates in roots. To determine if NO3- uptake rate changes in response to variations in translocation rate of carbohydrates from shoot to roots per se or to carbohydrate status of the roots, the night period was interrupted with a low light level from incandescent lamps to alter the diurnal pattern of NO3- uptake by roots and export of carbohydrate from shoots of nonnodulated soybean. Depletion of NO3- from replenished, complete nutrient solutions containing 1 mM NO3- was measured by ion chromatography and rates of NO3- uptake were calculated. Changes in export of carbohydrates from shoot to roots during intervals of the night period were calculated as the differences between rates of disappearance in contents of nonstructural carbohydrates and their estimated rates of utilization in shoot respiration and growth. A positive, significant correlation occurred between changes in calculated rates of carbohydrate export from shoots and NO3- uptake rates. Conversely, there was no significant correlation between concentrations of nonstructural carbohydrates in roots and NO3- uptake rates. These results support the hypothesis that carbohydrate flux from shoot to roots has a direct role in regulation of nitrogen uptake by the whole plant.

Effects of ovariectomy and intrinsic aerobic capacity on tissue-specific insulin sensitivity

PubMed Central

Park, Young-Min; Rector, R. Scott; Thyfault, John P.; Zidon, Terese M.; Padilla, Jaume; Welly, Rebecca J.; Meers, Grace M.; Morris, Matthew E.; Britton, Steven L.; Koch, Lauren G.; Booth, Frank W.; Kanaley, Jill A.

2015-01-01

High-capacity running (HCR) rats are protected against the early (i.e., ∼11 wk postsurgery) development of ovariectomy (OVX)-induced insulin resistance (IR) compared with low-capacity running (LCR) rats. The purpose of this study was to utilize the hyperinsulinemic euglycemic clamp to determine whether 1) HCR rats remain protected from OVX-induced IR when the time following OVX is extended to 27 wk and 2) tissue-specific glucose uptake differences are responsible for the protection in HCR rats under sedentary conditions. Female HCR and LCR rats (n = 40; aged ∼22 wk) randomly received either OVX or sham (SHM) surgeries and then underwent the clamp 27 wk following surgeries. [3-3H]glucose was used to determine glucose clearance, whereas 2-[14C]deoxyglucose (2-DG) was used to assess glucose uptake in skeletal muscle, brown adipose tissue (BAT), subcutaneous white adipose tissue (WAT), and visceral WAT. OVX decreased the glucose infusion rate and glucose clearance in both lines, but HCR had better insulin sensitivity than LCR (P < 0.05). In both lines, OVX significantly reduced glucose uptake in soleus and gastrocnemius muscles; however, HCR showed ∼40% greater gastrocnemius glucose uptake compared with LCR (P < 0.05). HCR also exhibited greater glucose uptake in BAT and visceral WAT compared with LCR (P < 0.05), yet these tissues were not affected by OVX in either line. In conclusion, OVX impairs insulin sensitivity in both HCR and LCR rats, likely driven by impairments in insulin-mediated skeletal muscle glucose uptake. HCR rats have greater skeletal muscle, BAT, and WAT insulin-mediated glucose uptake, which may aid in protection against OVX-associated insulin resistance. PMID:26646101

Toward a transport-based analysis of nutrient spiraling and uptake in streams

USGS Publications Warehouse

Runkel, Robert L.

2007-01-01

Nutrient addition experiments are designed to study the cycling of nutrients in stream ecosystems where hydrologic and nonhydrologic processes determine nutrient fate. Because of the importance of hydrologic processes in stream ecosystems, a conceptual model known as nutrient spiraling is frequently employed. A central part of the nutrient spiraling approach is the determination of uptake length (SW), the average distance traveled by dissolved nutrients in the water column before uptake. Although the nutrient spiraling concept has been an invaluable tool in stream ecology, the current practice of estimating uptake length from steady-state nutrient data using linear regression (called here the "SW approach") presents a number of limitations. These limitations are identified by comparing the exponential SW equation with analytical solutions of a stream solute transport model. This comparison indicates that (1) SW, is an aggregate measure of uptake that does not distinguish between main channel and storage zone processes, (2) SW, is an integrated measure of numerous hydrologie and nonhydrologic processes-this process integration may lead to difficulties in interpretation when comparing estimates of SW, and (3) estimates of uptake velocity and areal uptake rate (Vf and U) based on S W, are not independent of system hydrology. Given these findings, a transport-based approach to nutrient spiraling is presented for steady-state and time-series data sets. The transport-based approach for time-series data sets is suggested for future research on nutrient uptake as it provides a number of benefits, including the ability to (1) separately quantify main channel and storage zone uptake, (2) quantify specific hydrologic and nonhydrologic processes using various model parameters (process separation), (3) estimate uptake velocities and areal uptake rates that are independent of hydrologic effects, and (4) use short-term, non-plateau nutrient additions such that the effects of regeneration and mineralization are minimized. In summary, the transport-based, time-series approach provides a means of estimating traditional measures of nutrient uptake (SW, V?? U) while providing additional information on the location and magnitude of uptake (main channel versus storage zone). Application of the transport-based approach to time-series data from Green Creek, Antarctica, indicates that the bulk of nitrate uptake (???74% to 100%) occurred within the main channel where benthic uptake by algal mats is a likely process. Substantial uptake (???26%) also occurred in the storage zone of one reach, where uptake is attributed to the microbial community.

Can't take the heat: Temperature-enhanced toxicity in the mayfly Isonychia bicolor exposed to the neonicotinoid insecticide imidacloprid.

PubMed

Camp, A A; Buchwalter, D B

2016-09-01

Neonicotinoid insecticide usage has increased globally in recent decades. Neonicotinoids, such as imidacloprid, are potent insect neurotoxicants that may pose a threat to non-target aquatic organisms, such as aquatic insects. In nature, insects typically live in thermally fluctuating conditions, which may significantly alter both contaminant exposures and affects. Here we investigate the relationship between temperature and time-to-effect for imidacloprid toxicity with the aquatic insect Isonychia bicolor, a lotic mayfly. Additionally, we examined the mechanisms driving temperature-enhanced toxicity including metabolic rate, imidacloprid uptake rate, and tissue bioconcentration. Experiments included acute toxicity tests utilizing sublethal endpoints and mortality, as well as respirometry and radiotracer assays with [(14)C] imidacloprid. Further, we conducted additional uptake experiments with a suite of aquatic invertebrates (including I. bicolor, Neocloeon triangulifer, Macaffertium modestum, Pteronarcys proteus, Acroneuria carolinensis, and Pleuroceridae sp) to confirm and contextualize our findings from initial experiments. The 96h EC50 (immobility) for I. bicolor at 15°C was 5.81μg/L which was approximately 3.2 fold lower than concentrations associated with 50% mortality. Assays examining the impact of temperature were conducted at 15, 18, 21, and 24°C and demonstrated that time-to-effect for sublethal impairment and immobility was significantly decreased with increasing temperature. Uptake experiments with [(14)C] imidacloprid revealed that initial uptake rates were significantly increased with increasing temperature for I. bicolor, as were oxygen consumption rates. Further, in the separate experiment with multiple species across temperatures 15, 20, and 25°C, we found that all the aquatic insects tested had significantly increased imidacloprid uptake with increasing temperatures, with N. triangulifer accumulating the most imidacloprid on a mass-specific basis. Our acute toxicity results highlight the importance of evaluating sublethal endpoints, as profound impairments of motor function were evident far before mortality. Further, we demonstrate that temperature is a powerful modulator of sublethal toxicity within a range of environmentally relevant temperatures, impacting both uptake rates and metabolic rates of I. bicolor. Finally, we show that temperature alters imidacloprid uptake across a range of species, highlighting the physiological variation present within aquatic invertebrate communities and the challenge associated with relying solely on surrogate species. Taken together, this research points to the need to consider the role of temperature in toxicity assessments. Copyright © 2016 Elsevier B.V. All rights reserved.

Heart Rate and Oxygen Uptake Kinetics in Type 2 Diabetes Patients - A Pilot Study on the Influence of Cardiovascular Medication on Regulatory Processes.

PubMed

Koschate, Jessica; Drescher, Uwe; Baum, Klaus; Brinkmann, Christian; Schiffer, Thorsten; Latsch, Joachim; Brixius, Klara; Hoffmann, Uwe

2017-05-01

The aim of this pilot study was to investigate whether there are differences in heart rate and oxygen uptake kinetics in type 2 diabetes patients, considering their cardiovascular medication. It was hypothesized that cardiovascular medication would affect heart rate and oxygen uptake kinetics and that this could be detected using a standardized exercise test. 18 subjects were tested for maximal oxygen uptake. Kinetics were measured in a single test session with standardized, randomized moderate-intensity work rate changes. Time series analysis was used to estimate kinetics. Greater maxima in cross-correlation functions indicate faster kinetics. 6 patients did not take any cardiovascular medication, 6 subjects took peripherally acting medication and 6 patients were treated with centrally acting medication. Maximum oxygen uptake was not significantly different between groups. Significant main effects were identified regarding differences in muscular oxygen uptake kinetics and heart rate kinetics. Muscular oxygen uptake kinetics were significantly faster than heart rate kinetics in the group with no cardiovascular medication (maximum in cross-correlation function of muscular oxygen uptake vs. heart rate; 0.32±0.08 vs. 0.25±0.06; p=0.001) and in the group taking peripherally acting medication (0.34±0.05 vs. 0.28±0.05; p=0.009) but not in the patients taking centrally acting medication (0.28±0.05 vs. 0.30±0.07; n.s.). It can be concluded that regulatory processes for the achievement of a similar maximal oxygen uptake are different between the groups. The used standardized test provided plausible results for heart rate and oxygen uptake kinetics in a single measurement session in this patient group. © Georg Thieme Verlag KG Stuttgart · New York.

Specific Uptake of Lipid-Antibody-Functionalized LbL Microcarriers by Cells.

PubMed

Göse, Martin; Scheffler, Kira; Reibetanz, Uta

2016-11-14

The modular construction of Layer-by-Layer biopolymer microcarriers facilitates a highly specific design of drug delivery systems. A supported lipid bilayer (SLB) contributes to biocompatibility and protection of sensitive active agents. The addition of a lipid anchor equipped with PEG (shielding from opsonins) and biotin (attachment of exchangeable outer functional molecules) enhances the microcarrier functionality even more. However, a homogeneously assembled supported lipid bilayer is a prerequisite for a specific binding of functional components. Our investigations show that a tightly packed SLB improves the efficiency of functional components attached to the microcarrier's surface, as illustrated with specific antibodies in cellular application. Only a low quantity of antibodies is needed to obtain improved cellular uptake rates independent from cell type as compared to an antibody-functionalized loosely packed lipid bilayer or directly assembled antibody onto the multilayer. A fast disassembly of the lipid bilayer within endolysosomes exposing the underlying drug delivering multilayer structure demonstrates the suitability of LbL-microcarriers as a multifunctional drug delivery system.

Linking Fruit Ca Uptake Capacity to Fruit Growth and Pedicel Anatomy, a Cross-Species Study

PubMed Central

Song, Wenpei; Yi, Junwen; Kurniadinata, Odit F.; Wang, Huicong; Huang, Xuming

2018-01-01

Calcium (Ca) in flesh fruits is important for quality formation and maintenance. Most studies on fruit Ca focus on one species. This study attempted to understand some universal relations to fruit Ca uptake across species. Calcium contents in fruit tissues were analyzed in different fruits, including three cultivars of litchi, two cultivars each of grape and citrus, and one cultivar each of loquat, apple, pear, Indian jujube, and longan. In situ Ca distribution was revealed with electron probe and xylem functionality visualized by dye tracing. Fruit Ca uptake rate and activity were calculated and correlated with fruit growth and pedicel anatomy. The results showed that fruit Ca uptake rate was the highest in pomes (loquat, apple, and pear), followed by Indian jujube drupe, arillate fruits (litchis and longan) and citrus, while grape berries were the lowest. Fruit Ca uptake rate showed a strong positive correlation to growth rate. However, Ca uptake activity, reflecting Ca uptake rate relative to growth, was the highest in arillate fruits and loquat and lowest in grape berries, and had a poor correlation with fruit growth rate. In all fruits, Ca concentration in the pedicel was higher than in the fruit, and they displayed a good positive correlation. In the pedicel, Ca was most abundant in the phloem. Dye tracing showed that xylem function loss occurred with maturation in all species/varieties. Apple had the poorest xylem functionality with the least development of secondary xylem, but its Ca uptake rate was among the highest. Vessel density, size and area in the pedicel showed no correlation with fruit Ca uptake rate. It is concluded that: (1) fruit growth may be a key determinant of Ca uptake; (2) the universal pattern of Ca being higher in the pedicel than in the fruit indicates existence of a pedicel-fruit “bottleneck” effect in Ca transport across species; (3) xylem functionality loss with fruit maturation is also a universal event; (4) in the pedicel, Ca is more distributed in the phloem; (5) vessel morphology in the pedicel is not rate-limiting for fruit Ca uptake; (6) phloem pathway might contribute to fruit Ca uptake. PMID:29868049

Structure Dependence of Long-Chain [18F]Fluorothia Fatty Acids as Myocardial Fatty Acid Oxidation Probes

PubMed Central

Pandey, Mukesh K.; Belanger, Anthony P.; Wang, Shuyan; DeGrado, Timothy R.

2012-01-01

In-vivo imaging of regional fatty acid oxidation (FAO) rates would have considerable potential for evaluation of mammalian diseases. We have synthe sized and evaluated 18F-labeled thia fatty acid analogues as metabolically trapped FAO probes to understand the effect of chain length, degree of unsaturation and placement of the thia-substituent on myocardial uptake and retention. 18-[18F]fluoro-4-thia-(9Z)-octadec-9-enoic acid (3) showed excellent heart:background radioactivity concentration ratios along with highest retention in heart and liver. Pretreatment of rats with the CPT-1 inhibitor, POCA, caused >80% reduction in myocardial uptake of 16-[18F]fluoro-4-thia-hexadecanoic acid (2), and 3 indicating high specificity for FAO. In contrast, 18-[18F]fluoro-4-thia-octadecanoic acid (4), showed dramatically reduced myocardial uptake and blunted response to POCA. 18-[18F]fluoro-6-thia-octadecanoic acid (5), showed moderate myocardial uptake and no sensitivity of myocardial uptake to POCA. The results demonstrate relationships between structures of 18F-labelled thia fatty acid and uptake, and their utility as FAO probes in various tissues. PMID:23153307

40 CFR 503.33 - Vector attraction reduction.

Code of Federal Regulations, 2013 CFR

2013-07-01

... less than 15 percent, vector attraction reduction is achieved. (4) The specific oxygen uptake rate... shall be equal to or greater than 75 percent based on the moisture content and total solids prior to... the moisture content and total solids prior to mixing with other materials. (9)(i) Sewage sludge shall...

40 CFR 503.33 - Vector attraction reduction.

Code of Federal Regulations, 2014 CFR

2014-07-01

... less than 15 percent, vector attraction reduction is achieved. (4) The specific oxygen uptake rate... shall be equal to or greater than 75 percent based on the moisture content and total solids prior to... the moisture content and total solids prior to mixing with other materials. (9)(i) Sewage sludge shall...

40 CFR 503.33 - Vector attraction reduction.

Code of Federal Regulations, 2010 CFR

2010-07-01

... less than 15 percent, vector attraction reduction is achieved. (4) The specific oxygen uptake rate... shall be equal to or greater than 75 percent based on the moisture content and total solids prior to... the moisture content and total solids prior to mixing with other materials. (9)(i) Sewage sludge shall...

40 CFR 503.33 - Vector attraction reduction.

Code of Federal Regulations, 2011 CFR

2011-07-01

... less than 15 percent, vector attraction reduction is achieved. (4) The specific oxygen uptake rate... shall be equal to or greater than 75 percent based on the moisture content and total solids prior to... the moisture content and total solids prior to mixing with other materials. (9)(i) Sewage sludge shall...

40 CFR 503.33 - Vector attraction reduction.

Code of Federal Regulations, 2012 CFR

2012-07-01

... less than 15 percent, vector attraction reduction is achieved. (4) The specific oxygen uptake rate... shall be equal to or greater than 75 percent based on the moisture content and total solids prior to... the moisture content and total solids prior to mixing with other materials. (9)(i) Sewage sludge shall...

Inter- and intra-specific competition of duckweed under multiple heavy metal contaminated water.

PubMed

Zhao, Zhao; Shi, Huijuan; Kang, Xianjiang; Liu, Cunqi; Chen, Lingci; Liang, Xiaofei; Jin, Lei

2017-11-01

The influences of intra- and inter-species competition on ecosystems are poorly understood. Lemna aequinoctialis and Spirodela polyrhiza were used to assess the effects of exposure to different concentrations of multiple heavy metals (copper-cadmium-zinc), when the plants were grown in mixed- or mono-culture. Parameters assessed included relative growth rate (RGR), content of chlorophyll, glutathione (GSH), malondialdehyde (MDA), as well as the activity of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD). Inter-specific competition was affected by metal concentration, with results indicating that inter-specific competition significantly affected duckweed growth and metal uptake in different heavy metal exposure conditions. Inter-specific competition increased growth rate of duckweed under high metal concentrations, although when compared with intra-specific competition, it caused no obvious differences under low metal concentrations. The growth of L. aequinoctialis was further increased in mixed culture when exposed to high metal concentrations, with inter-specific competition increasing the content of cadmium and zinc, while decreasing copper content of L. aequinoctialis compared with under intra-specific conditions. Conversely, inter-specific competition increased the content of copper and cadmium of S. polyrhiza, without causing obvious differences in zinc accumulation under high ambient concentrations. Under high metal conditions, inter-specific competition increased antioxidant enzyme activities in duckweed species, increasing resistance to heavy metals. Results show that inter-specific competition makes duckweed develop mechanisms to increase fitness and survival, such as enhancement of antioxidant enzyme activities, rather than limiting metal uptake when exposed to high concentrations of multiple metals. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Demon voltammetry and analysis software: Analysis of cocaine-induced alterations in dopamine signaling using multiple kinetic measures

PubMed Central

Yorgason, Jordan T.; España, Rodrigo A.; Jones, Sara R.

2011-01-01

The fast sampling rates of fast scan cyclic voltammetry make it a favorable method for measuring changes in brain monoamine release and uptake kinetics in slice, anesthetized, and freely moving preparations. The most common analysis technique for evaluating changes in dopamine signaling uses well-established Michaelis-Menten kinetic methods that can accurately model dopamine release and uptake parameters across multiple experimental conditions. Nevertheless, over the years, many researchers have turned to other measures to estimate changes in dopamine release and uptake, yet to our knowledge no systematic comparison amongst these measures has been conducted. To address this lack of uniformity in kinetic analyses, we have created the Demon Voltammetry and Analysis software suite, which is freely available to academic and non-profit institutions. Here we present an explanation of the Demon Acquisition and Analysis features, and demonstrate its utility for acquiring voltammetric data under in vitro, in vivo anesthetized, and freely moving conditions. Additionally, the software was used to compare the sensitivity of multiple kinetic measures of release and uptake to cocaine-induced changes in electrically evoked dopamine efflux in nucleus accumbens core slices. Specifically, we examined and compared tau, full width at half height, half-life, T20, T80, slope, peak height, calibrated peak dopamine concentration, and area under the curve to the well-characterized Michaelis-Menten parameters, dopamine per pulse, maximal uptake rate, and apparent affinity. Based on observed results we recommend tau for measuring dopamine uptake and calibrated peak dopamine concentration for measuring dopamine release. PMID:21392532

Switching industrial production processes from complex to defined media: method development and case study using the example of Penicillium chrysogenum.

PubMed

Posch, Andreas E; Spadiut, Oliver; Herwig, Christoph

2012-06-22

Filamentous fungi are versatile cell factories and widely used for the production of antibiotics, organic acids, enzymes and other industrially relevant compounds at large scale. As a fact, industrial production processes employing filamentous fungi are commonly based on complex raw materials. However, considerable lot-to-lot variability of complex media ingredients not only demands for exhaustive incoming components inspection and quality control, but unavoidably affects process stability and performance. Thus, switching bioprocesses from complex to defined media is highly desirable. This study presents a strategy for strain characterization of filamentous fungi on partly complex media using redundant mass balancing techniques. Applying the suggested method, interdependencies between specific biomass and side-product formation rates, production of fructooligosaccharides, specific complex media component uptake rates and fungal strains were revealed. A 2-fold increase of the overall penicillin space time yield and a 3-fold increase in the maximum specific penicillin formation rate were reached in defined media compared to complex media. The newly developed methodology enabled fast characterization of two different industrial Penicillium chrysogenum candidate strains on complex media based on specific complex media component uptake kinetics and identification of the most promising strain for switching the process from complex to defined conditions. Characterization at different complex/defined media ratios using only a limited number of analytical methods allowed maximizing the overall industrial objectives of increasing both, method throughput and the generation of scientific process understanding.

Switching industrial production processes from complex to defined media: method development and case study using the example of Penicillium chrysogenum

PubMed Central

2012-01-01

Background Filamentous fungi are versatile cell factories and widely used for the production of antibiotics, organic acids, enzymes and other industrially relevant compounds at large scale. As a fact, industrial production processes employing filamentous fungi are commonly based on complex raw materials. However, considerable lot-to-lot variability of complex media ingredients not only demands for exhaustive incoming components inspection and quality control, but unavoidably affects process stability and performance. Thus, switching bioprocesses from complex to defined media is highly desirable. Results This study presents a strategy for strain characterization of filamentous fungi on partly complex media using redundant mass balancing techniques. Applying the suggested method, interdependencies between specific biomass and side-product formation rates, production of fructooligosaccharides, specific complex media component uptake rates and fungal strains were revealed. A 2-fold increase of the overall penicillin space time yield and a 3-fold increase in the maximum specific penicillin formation rate were reached in defined media compared to complex media. Conclusions The newly developed methodology enabled fast characterization of two different industrial Penicillium chrysogenum candidate strains on complex media based on specific complex media component uptake kinetics and identification of the most promising strain for switching the process from complex to defined conditions. Characterization at different complex/defined media ratios using only a limited number of analytical methods allowed maximizing the overall industrial objectives of increasing both, method throughput and the generation of scientific process understanding. PMID:22727013

Maple sap uptake, exudation, and pressure changes correlated with freezing exotherms and thawing endotherms.

PubMed

Tyree, M T

1983-10-01

Sap flow rates and sap pressure changes were measured in dormant sugar maple trees (Acer saccharum Marsh.). In the forest, sap flow rates and pressure changes were measured from tap holes drilled into tree trunks in mature trees and sap flow rates were measured from the base of excised branches. Excised branches were also brought into the laboratory where air temperature could be carefully controlled in a refrigerated box and sap flow rates and sap pressures were measured from the cut base of the branches.Under both forest and laboratory conditions, sap uptake occurred as the wood temperature declined but much more rapid sap uptake correlated with the onset of the freezing exotherm. When sap pressures were measured under conditions of negligible volume displacement, the sap pressure rapidly fell to -60 to -80 kilopascals at the start of the freezing exotherm. The volume of water uptake and the rate of uptake depended on the rate of freezing. A slow freezing rate correlated with a large volume of water uptake, a fast freezing rate induced a smaller volume of water uptake. The volume of water uptake ranged from 0.02 to 0.055 grams water per gram dry weight of sapwood. The volume of water exuded after thawing was usually less than the volume of uptake so that after several freezing and thawing cycles the sapwood water content increased from 0.7 to 0.8 grams water per gram dry weight.These results are discussed in terms of a physical model of the mechanism of maple sap uptake and exudation first proposed by P. E. R. O'Malley. The proposed mechanism of sap uptake is by vapor distillation in air filled wood fiber lumina during the freezing of minor branches. Gravity and pressurized air bubbles (compressed during freezing) cause sap flow from the canopy down the tree after the thaw.

Maple Sap Uptake, Exudation, and Pressure Changes Correlated with Freezing Exotherms and Thawing Endotherms 1

PubMed Central

Tyree, Melvin T.

1983-01-01

Sap flow rates and sap pressure changes were measured in dormant sugar maple trees (Acer saccharum Marsh.). In the forest, sap flow rates and pressure changes were measured from tap holes drilled into tree trunks in mature trees and sap flow rates were measured from the base of excised branches. Excised branches were also brought into the laboratory where air temperature could be carefully controlled in a refrigerated box and sap flow rates and sap pressures were measured from the cut base of the branches. Under both forest and laboratory conditions, sap uptake occurred as the wood temperature declined but much more rapid sap uptake correlated with the onset of the freezing exotherm. When sap pressures were measured under conditions of negligible volume displacement, the sap pressure rapidly fell to −60 to −80 kilopascals at the start of the freezing exotherm. The volume of water uptake and the rate of uptake depended on the rate of freezing. A slow freezing rate correlated with a large volume of water uptake, a fast freezing rate induced a smaller volume of water uptake. The volume of water uptake ranged from 0.02 to 0.055 grams water per gram dry weight of sapwood. The volume of water exuded after thawing was usually less than the volume of uptake so that after several freezing and thawing cycles the sapwood water content increased from 0.7 to 0.8 grams water per gram dry weight. These results are discussed in terms of a physical model of the mechanism of maple sap uptake and exudation first proposed by P. E. R. O'Malley. The proposed mechanism of sap uptake is by vapor distillation in air filled wood fiber lumina during the freezing of minor branches. Gravity and pressurized air bubbles (compressed during freezing) cause sap flow from the canopy down the tree after the thaw. PMID:16663208

Phosphorus dynamics in biogeochemically distinct regions of the southeast subtropical Pacific Ocean

NASA Astrophysics Data System (ADS)

Duhamel, Solange; Björkman, Karin M.; Repeta, Daniel J.; Karl, David M.

2017-02-01

The southeast subtropical Pacific Ocean was sampled along a zonal transect between the coasts of Chile and Easter Island. This remote area of the world's ocean presents strong gradients in physical (e.g., temperature, density and light), chemical (e.g., salinity and nutrient concentrations) and microbiological (e.g., cell abundances, biomass and specific growth rates) properties. The goal of this study was to describe the phosphorus (P) dynamics in three main ecosystems along this transect: the upwelling regime off the northern Chilean coast, the oligotrophic area associated with the southeast subtropical Pacific gyre and the transitional area in between these two biomes. We found that inorganic phosphate (Pi) concentrations were high and turnover times were long (>210 nmol l-1 and >31 d, respectively) in the upper water column, along the entire transect. Pi uptake rates in the gyre were low (euphotic layer integrated rates were 0.26 mmol m-2 d-1 in the gyre and 1.28 mmol m-2 d-1 in the upwelling region), yet not only driven by decreases in particle mass or cell abundance (particulate P- and cell- normalized Pi uptake rates in the euphotic layer were ∼1-4 times and ∼3-15 times lower in the gyre than in the upwelling, respectively). However these Pi uptake rates were at or near the maximum Pi uptake velocity (i.e., uptake rates in Pi amended samples were not significantly different from those at ambient concentration: 1.5 and 23.7 nmol l-1 d-1 at 50% PAR in the gyre and upwelling, respectively). Despite the apparent Pi replete conditions, selected dissolved organic P (DOP) compounds were readily hydrolyzed. Nucleotides were the most bioavailable of the DOP substrates tested. Microbes actively assimilated adenosine-5‧-triphosphate (ATP) leading to Pi and adenosine incorporation as well as Pi release to the environment. The southeast subtropical Pacific Ocean is a Pi-sufficient environment, yet DOP hydrolytic processes are maintained and contribute to P-cycling across the wide range of environmental conditions present in this ecosystem.

Current barriers and potential strategies to increase the use of long-acting reversible contraception (LARC) to reduce the rate of unintended pregnancies in Australia: An expert roundtable discussion.

PubMed

Mazza, Danielle; Bateson, Deborah; Frearson, Meredith; Goldstone, Philip; Kovacs, Gab; Baber, Rod

2017-04-01

Australia's abortion rates are among the highest in the developed world. Efficacy of the most commonly used form of contraception (oral contraceptives and condoms) relies on regular user compliance. Long-acting reversible contraception (LARC) virtually eradicates contraceptive failure as it is not user-dependent; however, its uptake has been low. To provide an overview of barriers to LARC use in Australia and potential strategies to overcome these barriers. A roundtable of Australian experts was convened to share clinical perspectives and to explore the barriers and potential strategies to increase LARC use. Three broad barriers to LARC uptake were identified. (i) A paucity of Australian research exists that impedes closure of evidence gaps regarding contraceptive prescription and use. Systematic data collection is required. (ii) Within primary care, lack of familiarity with LARC and misperceptions about its use, lack of access to general practitioners (GPs) trained in LARC insertion/removal and affordability impede LARC uptake. Potential strategies to encourage LARC use include, GP education to promote informed choice by women, training in LARC insertions/removals, effective funding models for nurses to perform LARC insertions/removals, and rapid referral pathways. (iii) At the health system level, primary care incentives to provide LARC to women and health economic analyses to inform government policy changes are required. Although LARC decreases unintended pregnancies by eliminating user compliance issues, its uptake is low in Australia. Strategies that promote LARC uptake by targeting specific barriers may effectively reduce Australia's high unintended pregnancy rate. © 2017 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.

Needle age and season influence photosynthetic temperature response and total annual carbon uptake in mature Picea mariana trees

DOE PAGES

Jensen, Anna M.; Warren, Jeffrey; Hanson, Paul J.; ...

2015-01-01

Using seasonal- and cohort-specific photosynthetic temperature response functions, we quantified the physiological significance of maintaining multiple foliar cohorts in mature (~40-45 year old) Picea mariana trees in an ombrotrophic Sphagnum-bog, northern Minnesota, USA. We measured photosynthetic capacity, foliar respiration (Rd), biochemistry and morphology to estimate annual carbon (C) uptake by cohort, season and canopy position. Temperature response of key photosynthetic parameters at 25 C (i.e., light-saturated rate of CO 2 assimilation (Asat), light-saturated rate of Rubisco carboxylation (Vcmax), light-saturated electron transport rate (Jmax)) were clearly dependent on season and were generally less responsive in younger needles. Temperature optimums range betweenmore » 18.7-23.7, 31.3-38.3 and 28.7-36.7 C for Asat, Vcmax and Jmax respectively. Current-year (Y0) foliage had lower photosynthetic capacities compared to one-year-old (Y1) and two-year-old (Y2) foliage. As Y0 needles matured, values of Asat, Vcmax, Jmax, foliar LMA and nitrogen increased. Values of Vcmax, Jmax and Rd were related to foliar nitrogen but only in the youngest (Y0) cohort. Foliar ontogeny affected photosynthetic capacity more than growth temperature. Morphological and physiological cohort differences were reflected by their annual contribution to modeled C uptake, with a ~36% lower estimated annual C uptake by Y0 needles (LAI 0.52 m 2m -2) compared to Y1&2 cohorts (LAI 0.67 m 2m -2). Collectively, these results illustrate the physiological and ecological significance of characterizing multiple foliar cohorts during bud break and throughout the growth season, and for cumulative C uptake model estimates.« less

A geographical and seasonal comparison of nitrogen uptake by phytoplankton in the Southern Ocean

NASA Astrophysics Data System (ADS)

Philibert, R.; Waldron, H.; Clark, D.

2015-03-01

The impact of light and nutrients (such as silicate and iron) availability on nitrogen uptake and primary production vary seasonally and regionally in the Southern Ocean. The seasonal cycle of nitrogen uptake by phytoplankton in the Southern Ocean is not fully resolved over an annual scale due to the lack of winter in situ measurements. In this study, nitrate and ammonium uptake rates were measured using 15N tracers during a winter cruise in July 2012 and a summer cruise in February-March 2013. The winter cruise consisted of two legs: leg 1 extended from Cape Town to the ice margin along the GoodHope line and leg 2 stretched from the ice margin to Marion Island. The summer cruise was mostly focused on the subantarctic zone of the Atlantic sector. In winter, nitrogen uptake rates were measured at 55 and 1% of the surface photosynthetically active radiation (sPAR). The summer uptake rates were measured at four light depths corresponding to 55, 30, 10 and 3% sPAR. The integrated nitrate uptake rates during the winter cruise ranged from 0.17 to 5.20 mmol N m-2 d-1 (average 1.14 mmol N m-2 d-1) while the ammonium uptake rates ranged from 0.60 to 32.86 mmol N m-2 d-1 (average 6.73 mmol N m-2 d-1). During the summer cruise, the mean-integrated nitrate uptake rate was 0.20 mmol N m-2 d-1 with a range between 0.10 and 0.38 mmol N m-2 d-1. The integrated ammonium uptake rate averaged 4.39 mmol N m-2 d-1 and ranged from 1.12 to 9.05 mmol N m-2 d-1. The factors controlling nitrogen uptake in winter and summer were investigated. During the winter cruise, it was found that the different nitrogen uptake regimes were not separated by the fronts of the Antarctic Circumpolar Current (ACC). Light (in terms of day length) and ammonium concentration had the most influence on the nitrogen uptake. In the summer, increases in the mixed layer depth (MLD) resulted in increased nitrogen uptake rates. This suggests that the increases in the MLD could be alleviating nutrient limitations experienced by the phytoplankton at the end of summer.

Influence of substrate diffusion on degradation of dibenzofuran and 3-chlorodibenzofuran by attached and suspended bacteria.

PubMed Central

Harms, H; Zehnder, A J

1994-01-01

Dibenzofuran uptake-associated kinetic parameters of suspended and attached Sphingomonas sp. strain HH19k cells were compared. The suspended cells were studied in a batch system, whereas glass beads in percolated columns were used as the solid support for attached cells. The maximum specific activities of cells in the two systems were the same. The apparent half-maximum uptake rate-associated concentrations (Kt') of attached cells, however, were considerably greater than those of suspended cells and depended on cell density and on percolation velocity. A mathematical model was developed to explain the observed differences in terms of substrate transport to the cells. This model was based on the assumptions that the intrinsic half-maximum uptake rate-associated concentration (Kt) was unchanged and that deviations of Kt' from Kt resulted from the stereometry and the hydrodynamics around the cells. Our calculations showed that (i) diffusion to suspended cells and to single attached cells is efficient and therefore only slightly affects Kt'; (ii) diffusion to cells located on crowded surfaces is considerably lower than that to single attached cells and greatly increases Kt', which depends on the cell density; (iii) the convective-diffusive transport to attached cells that occurs in a percolated column is influenced by the liquid flow and results in dependency of Kt' on the flow rate; and (iv) higher specific affinity of cells correlates with higher susceptibility to diffusion limitation. Properties of the experimental system which limited quantitative proof of exclusively transport-controlled variations of Kt' are discussed. PMID:8085817

Development of accelerated net nitrate uptake. [Zea mays L

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

MacKown, C.T.; McClure, P.R.

1988-05-01

Upon initial nitrate exposure, net nitrate uptake rates in roots of a wide variety of plants accelerate within 6 to 8 hours to substantially greater rates. Effects of solution nitrate concentrations and short pulses of nitrate ({le}1 hour) upon nitrate-induced acceleration of nitrate uptake in maize (Zea mays L.) were determined. Root cultures of dark-grown seedlings, grown without nitrate, were exposed to 250 micromolar nitrate for 0.25 to 1 hour or to various solution nitrate concentration (10-250 micromolar) for 1 hour before returning them to a nitrate-free solution. Net nitrate uptake rates were assayed at various periods following nitrate exposuremore » and compared to rates of roots grown either in the absence of nitrate (CaSO{sub 4}-grown) or with continuous nitrate for at least 20 hours. Three hours after initial nitrate exposure, nitrate pulse treatments increased nitrate uptake rates three- to four-fold compared to the rates of CaSO{sub 4}-grown roots. When cycloheximide (5 micrograms per milliliter) was included during a 1-hour pulse with 250 micromolar nitrate, development of the accelerated nitrate uptake state was delayed. Otherwise, nitrate uptake rates reached maximum values within 6 hours before declining. Maximum rates, however, were significantly less than those of roots exposed continuously for 20, 32, or 44 hours. Pulsing for only 0.25 hour with 250 micromolar nitrate and for 1 hour with 10 micromolar caused acceleration of nitrate uptake, but the rates attained were either less than or not sustained for a duration comparable to those of roots pulsed for 1 hour with 250 micromolar nitrate. These results indicate that substantial development of nitrate-induced accelerated nitrate uptake state can be achieved by small endogenous accumulations of nitrate, which appear to moderate the activity or level of root nitrate uptake.« less

Nitrogen and phosphorus treatment of marine wastewater by a laboratory-scale sequencing batch reactor with eco-friendly marine high-efficiency sediment.

PubMed

Cho, Seonghyeon; Kim, Jinsoo; Kim, Sungchul; Lee, Sang-Seob

2017-06-22

We screened and identified a NH 3 -N-removing bacterial strain, Bacillus sp. KGN1, and a [Formula: see text] removing strain, Vibrio sp. KGP1, from 960 indigenous marine isolates from seawater and marine sediment from Tongyeong, South Korea. We developed eco-friendly high-efficiency marine sludge (eco-HEMS), and inoculated these marine bacterial strains into the marine sediment. A laboratory-scale sequencing batch reactor (SBR) system using the eco-HEMS for marine wastewater from land-based fish farms improved the treatment performance as indicated by 88.2% removal efficiency (RE) of total nitrogen (initial: 5.6 mg/L) and 90.6% RE of total phosphorus (initial: 1.2 mg/L) under the optimal operation conditions (food and microorganism (F/M) ratio, 0.35 g SCOD Cr /g mixed liquor volatile suspended solids (MLVSS)·d; dissolved oxygen (DO) 1.0 ± 0.2 mg/L; hydraulic retention time (HRT), 6.6 h; solids retention time (SRT), 12 d). The following kinetic parameters were obtained: cell yield (Y), 0.29 g MLVSS/g SCOD Cr ; specific growth rate (µ), 0.06 d -1 ; specific nitrification rate (SNR), 0.49 mg NH 3 -N/g MLVSS·h; specific denitrification rate (SDNR), 0.005 mg [Formula: see text]/g MLVSS·h; specific phosphorus uptake rate (SPUR), 0.12 mg [Formula: see text]/g MLVSS·h. The nitrogen- and phosphorus-removing bacterial strains comprised 18.4% of distribution rate in the microbial community of eco-HEMS under the optimal operation conditions. Therefore, eco-HEMS effectively removed nitrogen and phosphorus from highly saline marine wastewater from land-based fish farms with improving SNR, SDNR, and SPUR values in more diverse microbial communities. DO: dissolved oxygen; Eco-HEMS: eco-friendly high efficiency marine sludge; F/M: food and microorganism ratio; HRT: hydraulic retention time; ML(V)SS: mixed liquor (volatile) suspended solids; NCBI: National Center for Biotechnology Information; ND: not determined; qPCR: quantitative real-time polymerase chain reaction; RE: removal efficiency; SBR: sequencing batch reactor; SD: standard deviation; SDNR: specific denitrification rate; SNR: specific nitrification rate; SPUR: specific phosphate uptake rate; SRT: solids retention time; T-N: total nitrogen; T-P: total phosphorus; (V)SS: (volatile) suspended solids; w.w.: wet weight.

Effects of nutrients on specific growth rate of bacterioplankton in oligotrophic lake water cultures

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

Coveney, M.F.; Wetzel, R.G.

The effects of organic and inorganic nutrient additions on the specific growth rates of bacterioplankton in oligotrophic lake water cultures were investigated. Lake water was first passed through 0.8-{mu}m-pore-size filters (prescreening) to remove bacterivores and to minimize confounding effects of algae. Specific growth rates were calculated from changes in both bacterial cell numbers and biovolumes over 36 h. Gross specific growth rates in unmanipulated control samples were estimated through separate measurements of grazing losses by use of penicillin. The addition of mixed organic substrates alone to prescreened water did not significantly increase bacterioplankton specific growth rates. The addition of inorganicmore » phosphorus alone significantly increased one or both specific growth rates in three of four experiments, and one experiment showed a secondary stimulation by organic substrates. The stimulatory effects of phosphorus addition were greatest concurrently with the highest alkaline phosphatase activity in the lake water. Because bacteria have been shown to dominate inorganic phosphorus uptake in other P-deficient systems, the demonstration that phosphorus, rather than organic carbon, can limit bacterioplankton growth suggests direct competition between phytoplankton and bacterioplankton for inorganic phosphorus.« less

Who uses NHS health checks? Investigating the impact of ethnicity and gender and method of invitation on uptake of NHS health checks.

PubMed

Cook, Erica J; Sharp, Chloe; Randhawa, Gurch; Guppy, Andy; Gangotra, Raj; Cox, Jonathon

2016-01-20

NHS Health Checks is a national risk assessment prevention programme for all individuals aged 40-74 that reside in England. Through the systematic assessment of an individual's ten year disease risk, this programme aims to provide early identification and subsequent management of this risk. However, there is limited evidence on how socio-demographic factors impact on uptake and what influence the invitation method has on uptake to this programme. NHS Health Check data from April 2013 to March 2014 was analysed (N = 50,485) for all 30 GP Practices in Luton, a culturally diverse town in England, UK. Data was collected for age, ethnicity, uptake (attendance and non attendance) and invitation method (letter written, verbal face-to-face, telephone). Actual usage of NHS Health Checks was determined for each ethnic group of the population and compared using Chi-square analysis. The overall uptake rate for Luton was 44 %, markedly lower that the set target of 50-75 %. The findings revealed a variation of uptake in relation to age, gender, level of deprivation. Ethnicity and gender variations were also found, with 'White British' 'Black Caribbean' and 'Indian' patients most likely to take up a NHS Health Check. However, patients from 'Any Other White Background' and 'Black African' were significantly less likely to uptake an NHS Health Check compared to all other ethnic groups. Ethnicity and gender differences were also noted in relation to invitation method. The findings revealed that different invitation methods were effective for different ethnic and gender groups. Therefore, it is suggested that established protocols of invitation are specifically designed for maximizing the response rate for each population group. Future research should now focus on uncovering the barriers to uptake in particular culturally diverse population groups to determine how public health teams can better engage with these communities.

Uptake and metabolism of 14C-palmitate by fetal rabbit tissues.

PubMed

Hudson, D G; Hull, D

1977-01-01

The uptake and esterification of 14C-palmitate into lipid classes in placenta, fetal brown adipose tissue (BAT) and liver of rabbits were investigated in vitro. Fetal BAT showed a high rate of fatty acid uptake, 8.5 mumol-a-1 tissue-h-1. From 5 min onwards, the majority of incorporated label was in the triglyceride fraction. The placenta and fetal liver also incorporated I-[14C]-palmitate into both FFA and esterified lipid fractions, although at much lower rates than observed for BAT. In the liver, triglycerides, but in the placenta phospholipids, contained the majority of the label after 1 h incubation. BAT from both fetal and newborn rabbits released 14CO2 and the production of 14 CO2 was greater in the presence of noradrenaline. The specific activity of the CO2 was the same in stimulated and unstimulated tissue. It is concluded that BAT as well as the liver are important sites of free fatty acid removal from the fetal circulation. The potential for fatty acid oxidation is present in BAT of the 28-day rabbit fetus.

Vouchers for family planning and sexual and reproductive health services: a review of voucher programs involving Marie Stopes International among 11 Asian and African countries.

PubMed

Eva, Gillian; Quinn, Andrew; Ngo, Thoai D

2015-08-01

To evaluate provision of vouchers for family planning and sexual and reproductive health (SRH) services. A review was conducted to assess the effects of 24 voucher programs in Marie Stopes International programs across 11 countries in Asia and Africa between 2005 and the present. The outcome measures were uptake of services; service use among specific subgroups; user satisfaction with service quality; and efficiency of service delivery. Twelve of the 24 programs covered family planning only, whereas the other 12 programs covered family planning and/or SRH. Service uptake increased following implementation, although voucher redemption rates varied by program (44.1%-92.4%). Most programs were successful in reaching subgroups, such as the poor and young (under 25years), although this outcome depended on the targeting approach. Most programs recorded high user satisfaction; however, the evidence regarding efficiency was mixed. Vouchers increased uptake of services and, in some cases, improved service quality and reach to specific groups. Nevertheless, robust evaluation designs are required to measure efficiency. Copyright © 2015. Published by Elsevier Ireland Ltd.

Onset of and recovery from nitrogen stress during reproductive growth of soybean

NASA Technical Reports Server (NTRS)

Henry, L. T.; Raper, C. D. Jr; Rideout, J. W.; Raper CD, J. r. (Principal Investigator)

1992-01-01

Photosynthetic rates and allocation of dry matter, nitrogen, and nonstructural carbohydrates were determined during onset of and recovery from a nitrogen stress for reproductive soybean (Glycine max [L.] Merrill cv Ransom) plants. Until the beginning of seed fill, non-nodulated plants were grown in flowing solution culture with 1.0 mM NO3- in a complete nutrient solution. One set of plants then was transferred to minus-nitrogen solution for 24 d of seed fill; a second set was transferred to a minus-nitrogen solution for 14 d followed by return to the complete solution with 1.0 mM NO3- for the remaining 10 d of seed fill; and a third set was continued on the complete solution. Net CO2 exchange rates of individual leaves, which remained nearly constant during seed fill for nonstressed plants, declined at an accelerated rate during onset of nitrogen stress as the specific content of reduced nitrogen in the leaves was decreased by remobilization of nitrogen to support pod growth. The rate of nitrogen remobilization out of leaves initially was relatively greater than the decrease in photosynthetic rate. While rate of pod growth declined in response to the developing nitrogen stress, photosynthetic assimilation of carbon exceeded reproductive demand and nonstructural carbohydrates accumulated within tissues. Following resupply of exogenous NO3-, specific rate of NO3- uptake by roots was enhanced relative to nonstressed plants. While there was little increase in content of reduced nitrogen in leaves, net remobilization of nitrogen out of leaves ceased, and the decline in photosynthetic rate stabilized at about 51% of that for nonstressed plants. This level of photosynthesis, combined with the availability of elevated pools of carbohydrates accumulated during stress, was sufficient to support the increases in both the specific rates of NO3- uptake and the rate of pod growth during recovery.

Cyclic variations in nitrogen uptake rate of soybean plants: ammonium as a nitrogen source

NASA Technical Reports Server (NTRS)

Henry, L. T.; Raper, C. D. Jr

1989-01-01

When NO3- is the sole nitrogen source in flowing solution culture, the net rate of nitrogen uptake by nonnodulated soybean (Glycine max L. Merr. cv Ransom) plants cycles between maxima and minima with a periodicity of oscillation that corresponds with the interval of leaf emergence. Since soybean plants accumulate similar quantities of nitrogen when either NH4+ or NO3- is the sole source in solution culture controlled at pH 6.0, an experiment was conducted to determine if the oscillations in net rate of nitrogen uptake also occur when NH4+ is the nitrogen source. During a 21-day period of vegetative development, net uptake of NH4+ was measured daily by ion chromatography as depletion of NH4+ from a replenished nutrient solution containing 1.0 millimolar NH4+. The net rate of NH4+ uptake oscillated with a periodicity that was similar to the interval of leaf emergence. Instances of negative net rates of uptake indicate that the transition between maxima and minima involved changes in influx and efflux components of net NH4+ uptake.

Characterizing roots and water uptake in a ground cover rice production system.

PubMed

Li, Sen; Zuo, Qiang; Wang, Xiaoyu; Ma, Wenwen; Jin, Xinxin; Shi, Jianchu; Ben-Gal, Alon

2017-01-01

Water-saving ground cover rice production systems (GCRPS) are gaining popularity in many parts of the world. We aimed to describe the characteristics of root growth, morphology, distribution, and water uptake for a GCRPS. A traditional paddy rice production system (TPRPS) was compared with GCRPS in greenhouse and field experiments. In the greenhouse, GCRPS where root zone average soil water content was kept near saturation (GCRPSsat), field capacity (GCRPSfwc) and 80% field capacity (GCRPS80%), were evaluated. In a two-year field experiment, GCRPSsat and GCRPS80% were applied. Similar results were found in greenhouse and field experiments. Before mid-tillering the upper soil temperature was higher for GCRPS, leading to enhanced root dry weight, length, surface area, specific root length, and smaller diameter of roots but lower water uptake rate per root length compared to TPRPS. In subsequent growth stages, the reduced soil water content under GCRPS caused that the preponderance of root growth under GCRPSsat disappeared in comparison to TPRPS. Under other GCRPS treatments (GCRPSfwc and GCRPS80%), significant limitation on root growth, bigger root diameter and higher water uptake rate per root length were found. Discrepancies in soil water and temperature between TPRPS and GCRPS caused adjustments to root growth, morphology, distribution and function. Even though drought stress was inevitable after mid-tillering under GCRPS, especially GCRPS80%, similar or even enhanced root water uptake capacity in comparison to TPRPS might promote allocation of photosynthetic products to shoots and increase water productivity.

Manganese acquisition by Lactobacillus plantarum

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

Archibald, F.S.; Duong, M.N.

1984-04-01

Lactobacillus plantarum has an unusually high Mn(II) requirement for growth and accumulated over 30 mM intracellular Mn(II). The acquisition of Mn(II) by L. plantarum occurred via a specific active transport system powered by the transmembrane proton gradient. The Mn(II) uptake system has a K/sub m/ of 0.2 ..mu..M and a V/sub max/ of 24 nmol mg/sup -1/ of protein min/sup -1/. Above a medium Mn(II) concentration of 200 ..mu..M, the intracellular Mn(II) level was independent of the medium Mn(II) and unresponsive to oxygen stresses but was reduced by phosphate limitation. At a pH of 5.5, citrate, isocitrate, and cis-aconitate effectivelymore » promoted MN(II) uptake, although measurable levels of 1,5-(/sup 14/C)citrate were not accumulated. When cells were presented with equimolar Mn(II) and Cd(II), Cd(II) was preferentially taken up by the Mn(II) transport system. Both Mn(II) and Cd(II) uptake were greatly increased by Mn(II) starvation. Mn(II) uptake by Mn(II)-starved cells was subject to a negative feedback regulatory mechanism functioning less than 1 min after exposure of the cells to Mn(II) and independent of protein synthesis. When presented with a relatively large amount of exogenous Mn(II), Mn(II)-starved cells exhibited a measurable efflux of their internal Mn(II), but the rate was only a small fraction of the maximal Mn(II) uptake rate.« less

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.

Sugar uptake by intestinal basolateral membrane vesicles.

PubMed

Wright, E M; van Os, C H; Mircheff, A K

1980-03-27

A high yield of membrane vesicles was prepared from the basolateral surface of rat intestinal cells using an N2 cavitation bomb and density gradient centrifugation. The membranes were enriched 10-fold and were free of significatn contamination by brush border membranes and mitochondria. The rate of D-E114C]glucose and L-E13H]glucose uptake into the vesicle was measured using a rapid filtration technique. D-Glucose equilibrated within the vesicles with a half-time 1/25th that for L-glucose. The stereospecific uptake exhibited saturation kinetics with a Km of approx. 44 mM and a V of approx. 110 nmol . mg-1 min-1 at 10 degrees C. The activation energy for the process was 14 kcal . mol-1 below 15 degrees C and it approached 3 kcal . mol-1 above 22 degrees C. Carrier-mediated uptake was eliminated in the presence of 1 mM HgCl2 and 0.5 mM phloretin. The rate of transport was unaffected by the absence or presence of sodium concentration gradients. Competition studies demonstrated that all sugars with the D-glucose pyranose ring chair conformation shared the transport system, and that, with the possible exception of the -OH group at carbon No. 1, there were no specific requirements for an equatorial -OH group at any position in the pyranose ring. In the case of alpha-methyl-D-glucoside its inability to share the D-glucose transport system may be due to steric hindrance posed by the -OCH3 group rather than by a specific requirement for a free hydroxyl group at the position in the ring. It is concluded that sugars are transported across the basolateral membrane of the intestinal epithelium by a facilitated diffusion system reminiscent of that in human red blood cells.

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.

Solute-specific scaling of inorganic nitrogen and phosphorus uptake in streams

NASA Astrophysics Data System (ADS)

Hall, R. O., Jr.; Baker, M. A.; Rosi-Marshall, E. J.; Tank, J. L.; Newbold, J. D.

2013-11-01

Stream ecosystem processes such as nutrient cycling may vary with stream position in the network. Using a scaling approach, we examined the relationship between stream size and nutrient uptake length, which represents the mean distance that a dissolved solute travels prior to removal from the water column. Ammonium (NH4+) uptake length increased proportionally with stream size measured as specific discharge (discharge/stream width) with a scaling exponent = 1.01. In contrast, uptake lengths for nitrate (NO3-) and soluble reactive phosphorus (SRP) increased more rapidly than increases in specific discharge (scaling exponents = 1.19 for NO3- and 1.35 for SRP). Additionally, the ratio of inorganic nitrogen (N) uptake length to SRP uptake length declined with stream size; there was relatively lower demand for SRP compared to N as stream size increased. Finally, we related the scaling of uptake length with specific discharge to that of stream length using Hack's law and downstream hydraulic geometry. Ammonium uptake length increased less than proportionally with distance from the headwaters, suggesting a strong role for larger streams and rivers in regulating nutrient transport.

Kinetic studies of the acylation of pig muscle–d-glyceraldehyde 3-phosphate dehydrogenase by 1,3-diphosphoglycerate and of proton uptake and release in the overall enzyme mechanism

PubMed Central

Harrigan, P. J.; Trentham, D. R.

1973-01-01

In the presence of NAD+ the acylation by 1,3-diphosphoglycerate of the four active sites of pig muscle d-glyceraldehyde 3-phosphate dehydrogenase can be monitored at 365nm by the disappearance of the absorption band present in the binary complex of NAD+ and the enzyme. A non-specific salt effect decreased the acylation rate 25-fold when the ionic strength was increased from 0.10 to 1.0. This caused acylation to be the rate-limiting process in the enzyme-catalysed reductive dephosphorylation of 1,3-diphosphoglycerate at high ionic strength at pH8. The salt effect permitted investigation of the acylation over a wide range of conditions. Variation of pH from 5.4 to 8.6 produced at most a two-fold change in the acylation rate. One proton was taken up per site acylated at pH8.0. By using a chromophoric H+ indicator the rate of proton uptake could be monitored during the acylation and was also almost invariant in the pH range 5.5–8.5. Transient kinetic studies of the overall enzyme-catalysed reaction indicated that acylation was the process involving proton uptake at pH8.0. The enzyme mechanism is discussed in the light of these results. PMID:4360248

Effects of carbon-to-sulfur (C/S) ratio and nitrate (N) dosage on Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorus Removal (DS-EBPR)

PubMed Central

Yu, Mei; Lu, Hui; Wu, Di; Zhao, Qing; Meng, Fangang; Wang, Yudan; Hao, Xiaodi; Chen, Guang-Hao

2016-01-01

In this study, the Denitrifying Sulfur cycle-associated Enhanced Biological Phosphorous Removal (DS-EBPR) with 20 mg P/L/d of the volumetric P removal rate was successfully achieved in a Sequencing Batch Reactor (SBR). The effects of carbon-to-sulfur (C/S) mass ratio and nitrate (N) dosage were investigated through two batch tests to reveal the role of wastewater compositions in DS-EBPR performance. The optimal specific P release and uptake rates (0.4 and 2.4 mg P/g VSS/h, respectively) were achieved at C/S/P/N mass ratio of 150/200/20/20, and poly-S is supplied as a potential electron and energy storage. The nitrate dosage in a range of 10–50 mg N/L had no significant influence on P uptake rates (2.1 ~ 2.4 mg P/g VSS/h), but significantly affected the storage of inclusion poly-S, the poly-S oxidation rate was increased about 16% while dosing nitrate from 20 to 30 mg N/L. It implies that nitrate is denitrified in the P uptake phase, and excess nitrate is further consumed by poly-S. Moreover, the microbial analysis showed that the functional bacteria should mostly belong to denitrifying bacteria or Unclassified genera. PMID:26983801

Decisional Stage Distribution for Colorectal Cancer Screening among Diverse, Low-Income Study Participants

ERIC Educational Resources Information Center

Hester, C. M.; Born, W. K.; Yeh, H. W.; Young, K. L.; James, A. S.; Daley, C. M.; Greiner, K. A.

2015-01-01

Colorectal cancer (CRC) screening uptake among minorities and those with lower incomes is suboptimal. Behavioral interventions specifically tailored to these populations can increase screening rates and save lives. The Precaution Adoption Process Model (PAPM) allows assignment of a decisional stage for adoption of a behavior such as CRC screening.…

Development of a (99m)Tc-labeled lactam bridge-cyclized alpha-MSH derivative peptide as a possible single photon imaging agent for melanoma tumors.

PubMed

Shamshirian, Danial; Erfani, Mostafa; Beiki, Davood; Fallahi, Babak; Shafiei, Mohammad

2015-10-01

Melanocortin-1 (MC1) receptor is an attractive melanoma-specific target which has been used for melanoma imaging and therapy. In this work, a new lactam bridge α-MSH analog was labeled with (99m)Tc via HYNIC and EDDA/tricine as coligands including gamma aminobutyric acid (GABA) as a three carbon chain spacer between HYNIC and the N-terminus of the cyclic peptide. Also, stability in human serum, receptor bound internalization, in vivo tumor uptake, and tissue biodistribution were thoroughly investigated. HYNIC-GABA-Nle-CycMSHhept was synthesized using a standard Fmoc strategy. Labeling was performed at 95 °C and analysis involved instant thin layer chromatography and high performance liquid chromatography methods. The receptor bound internalization rate was studied in MC1 receptor expressing B16/F10 cells. Biodistribution of radiopeptide was studied in nude mice bearing B16/F10 tumor. Labeling yield of >98 % (n = 3) was obtained corresponding to a specific activity of 81 MBq/nmol. Peptide conjugate showed efficient stability in the presence of human serum. The radioligand showed specific internalization into B16/F10 cells (12.45 ± 1.1 % at 4 h). In biodistribution studies, a receptor-specific uptake was observed in MC1 receptor-positive organs so that after 2 h the uptake in mouse tumor was 5.10 ± 0.08 % ID/g, while low accumulation in the kidney uptake was observed (4.58 ± 0.68 % ID/g at 2 h after injection). The obtained results show that the presented new designed labeled peptide conjugate may be a suitable candidate for diagnosis of malignant tumors.

Root growth and function of three Mojave Desert grasses in response to elevated atmospheric CO2 concentration

USGS Publications Warehouse

Yoder, C.K.; Vivin, P.; DeFalco, L.A.; Seemann, J.R.; Nowak, R.S.

2000-01-01

Root growth and physiological responses to elevated CO2 were investigated for three important Mojave Desert grasses: the C3 perennial Achnatherum hymenoides, the C4 perennial Pleuraphis rigida and the C3 annual Bromus madritensis ssp. rubens. Seeds of each species were grown at ambient (360 μl l−1) or elevated (1000 μl l−1) CO2 in a glasshouse and harvested at three phenological stages: vegetative, anthesis and seed fill. Because P. rigida did not flower during the course of this study, harvests for this species represent three vegetative stages. Primary productivity was increased in both C3 grasses in response to elevated CO2 (40 and 19% for A. hymenoides and B. rubens, respectively), but root biomass increased only in the C3 perennial grass. Neither above-ground nor below-ground biomass of the C4 perennial grass was significantly affected by the CO2 treatment. Elevated CO2 did not significantly affect root surface area for any species. Total plant nitrogen was also not statistically different between CO2treatments for any species, indicating no enhanced uptake of N under elevated CO2. Physiological uptake capacities for NO3 and NH4 were not affected by the CO2 treatment during the second harvest; measurements were not made for the first harvest. However, at the third harvest uptake capacity was significantly decreased in response to elevated CO2 for at least one N form in each species. NO3 uptake rates were lower in A. hymenoides and P. rigida, and NH4 uptake rates were lower in B. rubens at elevated CO2. Nitrogen uptake on a whole root-system basis (NO3+NH4uptake capacity × root biomass) was influenced positively by elevated CO2 only for A. hymenoidesafter anthesis. These results suggest that elevated CO2 may result in a competitive advantage forA. hymenoides relative to species that do not increase root-system N uptake capacity. Root respiration measurements normalized to 20 °C were not significantly affected by the CO2treatment. However, specific root respiration was significantly correlated with either root C∶N ratio or root water content when all data per species were included within a simple regression model. The results of this study provide little evidence for up-regulation of root physiology in response to elevated CO2 and indicate that root biomass responses to CO2 are species-specific.

Inhibition of catalase-dependent ethanol metabolism in alcohol dehydrogenase-deficient deermice by fructose.

PubMed Central

Handler, J A; Bradford, B U; Glassman, E B; Forman, D T; Thurman, R G

1987-01-01

Hepatic microsomal fractions from ADH (alcohol dehydrogenase)-negative deermice incubated with an NADPH-generating system metabolized butanol and ethanol at rates around 10 nmol/min per mg. In contrast, cytosolic catalase from ADH-negative deermouse liver oxidized ethanol, but not butanol, when incubated with an H2O2-generating system. Thus butanol is oxidized by cytochrome P-450 in microsomal fractions, but not by cytosolic catalase, in tissues from ADH-negative deermice. In perfused livers from ADH-negative deermice, rates of ethanol uptake at low concentrations of ethanol (1.5 mM) were about 60 mumol/h per g, yet butanol (1.5 mM) uptake was undetectable (less than 4 mumol/h per g). At higher concentrations of alcohol (25-30 mM), rates of ethanol uptake were about 80 mumol/h per g, whereas rates of butanol uptake were only about 9 mumol/h per g. Because rates of butanol metabolism via cytochrome P-450 in deermice were more than an order of magnitude lower than rates of ethanol uptake in livers from ADH-negative deermice, it is concluded that ethanol uptake by perfused livers from ADH-negative deermice is catalysed predominantly via catalase-H2O2. In support of this conclusion, rates of H2O2 generation, which are rate-limiting for the peroxidation of ethanol by catalase, were about 65 mumol/h per g in livers from ADH-negative deermice, values similar to rates of ethanol uptake of about 60 mumol/h per g measured under identical conditions. Rates of ethanol uptake by perfused livers from ADH-positive, but not from ADH-negative, deermice were increased by about 50% by infusion of fructose. Thus it is concluded that the stimulation of hepatic ethanol uptake by fructose is dependent on the presence of ADH. Unexpectedly, fructose decreased rates of ethanol metabolism and H2O2 generation by about 60% in perfused livers from ADH-negative deermice, probably by decreasing activation of fatty acids and thus diminishing rates of peroxisomal beta-oxidation. PMID:3435455

Sortase Independent and Dependent Systems for Acquisition of Haem and Haemoglobin in Listeria monocytogenes

PubMed Central

Xiao, Qiaobin; Jiang, Xiaoxu; Moore, Kyle J.; Shao, Yi; Pi, Hualiang; Dubail, Iharilalao; Charbit, Alain; Newton, Salete M.; Klebba, Phillip E.

2011-01-01

Summary We studied three Fur-regulated systems of Listeria monocytogenes: the srtB region, that encodes sortase-anchored proteins and a putative ABC transporter, and the fhu and hup operons, that produce putative ABC transporters for ferric hydroxamates and haemin (Hn)/haemoglobin (Hb), respectively. Deletion of lmo2185 in the srtB region reduced listerial [59Fe]-Hn transport, and purified Lmo2185 bound [59Fe]-Hn (KD = 12 nM), leading to its designation as a Hn/Hb binding protein (hbp2). Purified Hbp2 also acted as a hemophore, capturing and supplying Hn from the environment. Nevertheless, Hbp2 only functioned in [59Fe]-Hn transport at external concentrations less than 10 nM: at higher Hn levels its uptake occurred with equivalent affinity and rate without Hbp2. Similarly, deletion of sortase A had no effect on ferric siderophore or Hn/Hb transport at any concentration, and the srtA-independence of listerial Hn/Hb uptake distinguished it from comparable systems of Staphylococcus aureus. In the cytoplasmic membrane, the Hup transporter was specific for Hn: its lipoprotein (HupD) only showed high affinity for the iron porphyrin (KD = 26 nM). Conversely, the FhuD lipoprotein encoded by the fhu operon had broad specificity: it bound both ferric siderophores and Hn, with the highest affinity for ferrioxamine B (KD = 123 nM). Deletions of Hup permease components hupD, hupG, or hupDGC reduced Hn/Hb uptake, and complementation of ΔhupC and ΔhupG by chromosomal integration of hupC+ and hupG+ alleles on pPL2 restored growth promotion by Hn/Hb. However, ΔhupDGC did not completely eliminate [59Fe]-Hn transport, implying the existence of another cytoplasmic membrane Hn transporter. The overall KM of Hn uptake by wild-type strain EGD-e was 1 nM, and it occurred at similar rates (Vmax = 23 pMol/109 cells/min) to those of ferric siderophore transporters. In the ΔhupDBGC strain uptake occurred at a 3-fold lower rate (Vmax = 7 pMol/109 cells/min). The results show that at low (< 50 nM) levels of Hn, SrtB-dependent peptidoglycan-anchored proteins (e.g., Hbp2) bind the porphyrin, and HupDGC or another transporter completes its uptake into the cytoplasm. However, at higher concentrations Hn uptake is SrtB-independent: peptidoglycan-anchored binding proteins are dispensable because HupDGC directly absorbs and internalizes Hn. Finally, ΔhupDGC increased the LD50 of L. monocytogenes 100-fold in the mouse infection model, reiterating the importance of this system in listerial virulence. PMID:21545655

Hydroponic Uptake of Atrazine and Lambda-cyhalothrin in Aquatic Macrophytes

NASA Astrophysics Data System (ADS)

Bouldin, J. L.; Farris, J. L.; Moore, M. T.; Smith, S.; Cooper, C. M.

2005-05-01

Phytoremediation encompasses an array of plant-associated processes known to mitigate contaminants from soil, sediment, and water. Modification of pesticides associated with agricultural runoff includes processes directly associated with aquatic macrophytes in addition to soil geochemical modifications and associated rhizospheric degradation. Remediation attributes of two vegetative species common to agricultural drainages in the Mississippi Delta, USA, were assessed using atrazine and lambda-cyhalothrin. Concentrations used in 8-d hydroponic exposures were calculated using recommended field applications and a 5% runoff model from a 0.65-cm rainfall event on a 2.02-ha field. While greater atrazine uptake was measured in Juncus effusus, greater lambda-cyhalothrin uptake occurred in Ludwigia peploides. Maximum pesticide uptake was reached within 48 h for each exposure and subsequent translocation of pesticides to upper plant biomass occurred in macrophytes exposed to atrazine. Sequestration of 98.2% of lambda-cyhalothrin in roots of L. peploides was measured after 8 d. Translocation of lambda-cyhalothrin in J. effusus resulted in 25.4% of pesticide uptake partitioned to upper plant biomass. These individual macrophyte remediation studies measured species- and pesticide-specific uptake rates, indicating that the seasonality of pesticide applications and macrophyte emergence might interact strongly to enhance mitigation capabilities in edge-of-field conveyance structures.

Hydroponic uptake of atrazine and lambda-cyhalothrin in Juncus effusus and Ludwigia peploides.

PubMed

Bouldin, J L; Farris, J L; Moore, M T; Smith, S; Cooper, C M

2006-11-01

Phytoremediation encompasses an array of plant-associated processes known to mitigate contaminants from soil, sediment, and water. Modification of pesticides associated with agricultural runoff includes processes directly associated with aquatic macrophytes in addition to changes in soil geochemistry and associated rhizospheric degradation. Remediation attributes of two vegetative species common to agricultural drainages in the Mississippi Delta, USA, were assessed using atrazine and lambda-cyhalothrin. Concentrations used in 8-d hydroponic exposures were calculated using recommended field applications and a 5% runoff model from a 0.65-cm rainfall event on a 2.02-ha field. While greater atrazine uptake was measured in Juncus effusus, greater lambda-cyhalothrin uptake occurred in Ludwigia peploides. Maximum pesticide uptake was reached within 48h for each exposure and subsequent translocation of pesticides to upper plant biomass occurred in macrophytes exposed to atrazine. Sequestration of 98.2% of lambda-cyhalothrin in roots of L. peploides was measured after 8d. Translocation of lambda-cyhalothrin in J. effusus resulted in 25.4% of pesticide uptake partitioned to upper plant biomass. These individual macrophyte remediation studies measured species- and pesticide-specific uptake rates, indicating that seasonality of pesticide applications and macrophyte emergence might interact strongly to enhance mitigation capabilities in edge-of-field conveyance structures.

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.

Associations of Methanotrophs With the Roots and Rhizomes of Aquatic Vegetation

NASA Technical Reports Server (NTRS)

King, Gary M.

1994-01-01

Results of an in vitro assay revealed that root-associated methane consumption was a common attribute or diverse emergent wetland macrophytes from a variety of habitats. Maximum potential uptake rates (V(sub maxp)) varied between about 1 and 10 micro mol g/ (dry weight) h, with no obvious correlation between rate and gross morphological characteristics of the plants. The V(sub maxp) corresponded to about 2 x 10(exp 18) to 2 x 10(exp 9) methanotrophs g/ (dry weight), assuming that root-associated methanotrophs have cell-specific activities comparable to those of known isolates. V(sub maxp) varied seasonally for an aquatic grass, Calamogrostis canadensis, and for the cattail, Typha latifolia, with highest rates in late summer. V(sub maxp) was well correlated with ambient temperature for C. canadensis but weakly correlated for T. Wifolia. The seasonal changes in V(sub maxp), as well as inferences from apparent half-saturation constants for methane uptake (K(sub app); generally 3 to 6 micro M), indicated that oxygen availability might be more important than methane as a rate determinant. In addition, roots incubated under anoxic conditions showed little or no postanoxia aerobic methane consumption, indicating that root-associated metbanotrophic populations might not tolerate variable oxygen availability. Hybridization of oligodeoxynucleotide probes specific for group 1 or group 2 methylotrophs also varied seasonally. The group 2-specific probe consistently hybridized to a greater extent than the group 1 probe, and the relative amount of group 2 probe hybridization to C. canadensis root extracts was positively correlated with V(sub maxp).

Recovery of phenotypes obtained by adaptive evolution through inverse metabolic engineering.

PubMed

Hong, Kuk-Ki; Nielsen, Jens

2012-11-01

In a previous study, system level analysis of adaptively evolved yeast mutants showing improved galactose utilization revealed relevant mutations. The governing mutations were suggested to be in the Ras/PKA signaling pathway and ergosterol metabolism. Here, site-directed mutants having one of the mutations RAS2(Lys77), RAS2(Tyr112), and ERG5(Pro370) were constructed and evaluated. The mutants were also combined with overexpression of PGM2, earlier proved as a beneficial target for galactose utilization. The constructed strains were analyzed for their gross phenotype, transcriptome and targeted metabolites, and the results were compared to those obtained from reference strains and the evolved strains. The RAS2(Lys77) mutation resulted in the highest specific galactose uptake rate among all of the strains with an increased maximum specific growth rate on galactose. The RAS2(Tyr112) mutation also improved the specific galactose uptake rate and also resulted in many transcriptional changes, including ergosterol metabolism. The ERG5(Pro370) mutation only showed a small improvement, but when it was combined with PGM2 overexpression, the phenotype was almost the same as that of the evolved mutants. Combination of the RAS2 mutations with PGM2 overexpression also led to a complete recovery of the adaptive phenotype in galactose utilization. Recovery of the gross phenotype by the reconstructed mutants was achieved with much fewer changes in the genome and transcriptome than for the evolved mutants. Our study demonstrates how the identification of specific mutations by systems biology can direct new metabolic engineering strategies for improving galactose utilization by yeast.

Controlled field evaluation of water flow rate effects on sampling polar organic compounds using polar organic chemical integrative samplers.

PubMed

Li, Hongxia; Vermeirssen, Etiënne L M; Helm, Paul A; Metcalfe, Chris D

2010-11-01

The uptake of polar organic contaminants into polar organic chemical integrative samplers (POCIS) varies with environmental factors, such as water flow rate. To evaluate the influence of water flow rate on the uptake of contaminants into POCIS, flow-controlled field experiments were conducted with POCIS deployed in channel systems through which treated sewage effluent flowed at rates between 2.6 and 37 cm/s. Both pharmaceutical POCIS and pesticide POCIS were exposed to effluent for 21 d and evaluated for uptake of pharmaceuticals and personal care products (PPCPs) and endocrine disrupting substances (EDS). The pesticide POCIS had higher uptake rates for PPCPs and EDS than the pharmaceutical POCIS, but there are some practical advantages to using pharmaceutical POCIS. The uptake of contaminants into POCIS increased with flow rate, but these effects were relatively small (i.e., less than twofold) for most of the test compounds. There was no relationship observed between the hydrophobicity (log octanol/water partition coefficient, log K(OW)) of model compounds and the effects of flow rate on the uptake kinetics by POCIS. These data indicate that water flow rate has a relatively minor influence on the accumulation of PPCPs and EDS into POCIS. © 2010 SETAC.

Evaluation of [99mTc/EDDA/HYNIC0]octreotide derivatives compared with [111In-DOTA0,Tyr3, Thr8]octreotide and [111In-DTPA0]octreotide: does tumor or pancreas uptake correlate with the rate of internalization?

PubMed

Storch, Daniel; Béhé, Martin; Walter, Martin A; Chen, Jianhua; Powell, Pia; Mikolajczak, Renata; Mäcke, Helmut R

2005-09-01

Radiolabeled somatostatin analogs are important tools for the in vivo localization and targeted radionuclide therapy of somatostatin receptor-positive tumors. The aim of this study was to compare 3 somatostatin analogs designed for the labeling with (99m)Tc (where HYNIC is 6-hydrazinopyridine-3-carboxylic acid): 6-hydrazinopyridine-3-carboxylic acid(0)-octreotide (HYNIC-OC/(99m)Tc-(1)), [HYNIC(0),Tyr(3)]octreotide (HYNIC-TOC/(99m)Tc-(2)), and [HYNIC(0),Tyr(3),Thr(8)]octreotide (HYNIC-TATE/(99m)Tc-(3)), using ethylenediamine-N,N'-diacetic acid (EDDA) as a coligand. In addition, we compared the (99m)Tc-labeled peptides [(111)In-diethylenetriaminepentaacetic acid(0)]octreotide ([(111)In-DTPA]-OC) and [(111)In-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid(0),Tyr(3),Thr(8)]octreotide ([(111)In-DOTA]-TATE) with regard to the rate of internalization and the biodistribution in AR4-2J (expressing the somatostatin receptor subtype 2) tumor-bearing rats. The main attention was directed toward a potential correlation between the rate of internalization and the tumor or pancreas uptake. Synthesis was performed on solid phase using a standard Fmoc strategy. Internalization was studied in cell culture (AR4-2J) and biodistribution was studied using a Lewis rat tumor model (AR4-2J). The 5 radiopeptides showed a specific internalization into AR4-2J cells in culture (as shown by blocking experiments). The rate of internalization of the 5 radiopeptides differed significantly according to the following order: (99m)Tc-(1) approximately = [(111)In-DTPA]-OC < (99m)Tc-(2) < (99m)Tc-(3) approximately = [(111)In-DOTA]-TATE. All radiopeptides displayed a rapid blood clearance and a fast clearance from all somatostatin receptor-negative tissues predominantly via the kidneys. A receptor-specific uptake of radioactivity was observed for all compounds in somatostatin receptor-positive organs such as the pancreas, the adrenals, and the stomach. After 4 h, the uptake in the AR4-2J tumor was comparable for (99m)Tc-(2) (3.85 +/- 1.0 injected dose per gram tissue (%ID/g)), (99m)Tc-(3) (3.99 +/- 0.58%ID/g), and [(111)In-DOTA]-TATE (4.12 +/- 0.74%ID/g) but much lower for [(111)In-DTPA]-OC (0.99 +/- 0.08%ID/g) and (99m)Tc-(1) (0.70 +/- 0.13%ID/g). The specificity was determined by blocking experiments using a large excess of [Tyr(3)]octreotide. (99m)Tc-(3) displayed the highest tumor-to-kidney ratio (2.5:1), followed by (99m)Tc(2) (1.9:1) and [(111)In-DOTA]-TATE (1.7:1). These data show that the 5 radiopeptides are specific radioligands for the somatostatin receptor subtype 2. The rate of internalization correlates with the uptake in the tumor (R(2) = 0.75; P = 0.026) and pancreas (R(2) = 0.98; P = 7.4.10(-5)). [Tyr(3),Thr(8)]octreotide derivatives show superiority over the corresponding octreotide and [Tyr(3)]octreotide derivatives, indicating that [(111)In-DOTA]-TATE and [(99m)Tc/EDDA/HYNIC]-TATE are suitable candidates for clinical studies.

Nitrogen uptake by wheat seedlings, interactive effects of four nitrogen sources: NO3-, NO2-, NH4+, and urea

NASA Technical Reports Server (NTRS)

Criddle, R. S.; Ward, M. R.; Huffaker, R. C.

1988-01-01

The net influx (uptake) rates of NO3-, NH4+, NO2-, and urea into roots of wheat (Triticum aestivum cv Yecora Rojo) seedlings from complete nutrient solutions containing all four compounds were monitored simultaneously. Although urea uptake was too slow to monitor, its presence had major inhibitory effects on the uptake of each of the other compounds. Rates of NO3-, NH4+, and NO2- uptake depended in a complex fashion on the concentration of all four N compounds. Equations were developed which describe the uptake rates of each of the compounds, and of total N, as functions of concentrations of all N sources. Contour plots of the results show the interactions over the range of concentrations employed. The coefficients of these equations provide quantitative values for evaluating primary and interactive effects of each compound on N uptake.

Uptake of free amino acids by bacteria-free larvae of the sand dollar Dendraster excentricus.

PubMed

Davis, J P; Stephens, G C

1984-10-01

Larvae of Dendraster excentricus were produced by collecting gametes and carrying out fertilization under aseptic conditions. Since gametes are free of bacteria in the gonad, bacteria-free (axenic) suspensions of larvae result. Net rates of entry of 14 amino acids and the rate of production of ammonia were simultaneously determined by high-performance liquid chromatography. The net rates of uptake of neutral amino acids were an order of magnitude greater than rates for basic and acidic amino acids. Influx of 14C-labeled leucine, arginine, and glutamate accurately reflects the net entry rate of these substrates. Uptake of amino acids by axenic suspensions of larvae was compared with uptake by suspensions prepared without aseptic precautions. There was no significant difference in net uptake of the 14 amino acids or in the pattern of oxidation and assimilation of [14C]leucine during short-term experiments of 4-h duration or less.

Novel alpha-MSH peptide analogs for melanoma targeting

NASA Astrophysics Data System (ADS)

Flook, Adam Michael

Skin cancer is the one of the most diagnosed cancers in the United States with increasing incidence over the past two decades. There are three major forms of skin cancer but melanoma is the deadliest. It is estimated that 76,690 new diagnoses of melanoma and 9,480 deaths will occur in 2013. Melanoma accounts for approximately 1.6% of all cancer related deaths and is the 5 th leading diagnosed cancer in the United States. The mean survival rate of patients diagnosed with metastatic melanoma is six months, with five year survival rates of less than 5%. In this project, we describe the design and characterization of novel melanoma-targeting peptide analogs for use in diagnostic imaging of both primary and metastatic melanoma lesions. Novel alpha-MSH peptide conjugates were designed to target the melanocortin-1 receptor present and over-expressed on melanoma cells. These peptides were synthesized and their in-vitro melanocortin-1 receptor binding affinities were established in murine melanoma cells. Once binding affinities were determined, the peptides were radiolabeled with 99mTc utilizing a novel direct radiolabeling technique developed in our laboratory. The peptides were purified via reverse-phase high performance liquid chromatography and in-vivo melanoma targeting and pharmacokinetic properties were determined in B16/F1 melanoma-bearing female C57BL/6 mice. Biodistribution and SPECT/CT imaging studies were performed with the promising 99m Tc-labeled peptide conjugates. All alpha-MSH peptide conjugates tested showed low nanomolar binding affinity for the melanocortin-1 receptor. All peptides were readily radiolabeld with 99mTc with greater than 95% radiochemical purity. All 99mTc-labeled peptides displayed high specific in-vivo melanoma tumor uptake while maintaining low normal organ accumulation, and were excreted through the urinary system in a timely fashion. In addition, all tested 99mTc-labeld alpha-MSH peptides demonstrated clear visualization of in-vivo tumor lesions with SPECT/CT. While all peptides exhibited high melanoma uptake, extremely high non-specific renal uptake was of concern. After synthesis of alpha-MSH peptide conjugates containing a different amino acid linker, renal uptake was drastically reduced and a lead compound had emerged, showing favorable in-vivo melanoma targeting and uptake properties with limited amounts of non-specific renal accumulation.

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

Jensen, Anna M.; Warren, Jeffrey; Hanson, Paul J.

Using seasonal- and cohort-specific photosynthetic temperature response functions, we quantified the physiological significance of maintaining multiple foliar cohorts in mature (~40-45 year old) Picea mariana trees in an ombrotrophic Sphagnum-bog, northern Minnesota, USA. We measured photosynthetic capacity, foliar respiration (Rd), biochemistry and morphology to estimate annual carbon (C) uptake by cohort, season and canopy position. Temperature response of key photosynthetic parameters at 25 C (i.e., light-saturated rate of CO 2 assimilation (Asat), light-saturated rate of Rubisco carboxylation (Vcmax), light-saturated electron transport rate (Jmax)) were clearly dependent on season and were generally less responsive in younger needles. Temperature optimums range betweenmore » 18.7-23.7, 31.3-38.3 and 28.7-36.7 C for Asat, Vcmax and Jmax respectively. Current-year (Y0) foliage had lower photosynthetic capacities compared to one-year-old (Y1) and two-year-old (Y2) foliage. As Y0 needles matured, values of Asat, Vcmax, Jmax, foliar LMA and nitrogen increased. Values of Vcmax, Jmax and Rd were related to foliar nitrogen but only in the youngest (Y0) cohort. Foliar ontogeny affected photosynthetic capacity more than growth temperature. Morphological and physiological cohort differences were reflected by their annual contribution to modeled C uptake, with a ~36% lower estimated annual C uptake by Y0 needles (LAI 0.52 m 2m -2) compared to Y1&2 cohorts (LAI 0.67 m 2m -2). Collectively, these results illustrate the physiological and ecological significance of characterizing multiple foliar cohorts during bud break and throughout the growth season, and for cumulative C uptake model estimates.« less

Similarity of nutrient uptake and root dimensions of Engelmann spruce and subalpine fir at two contrasting sites in Colorado

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

Yanai, R; McFarlane, K; Lucash, M

2009-10-09

Nutrient uptake capacity is an important parameter in modeling nutrient uptake by plants. Researchers commonly assume that uptake capacity measured for a species can be used across sites. We tested this assumption by measuring the nutrient uptake capacity of intact roots of Engelmann spruce (Picea engelmanni Parry) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) at Loch Vale Watershed and Fraser Experimental Forest in the Rocky Mountains of central Colorado. Roots still attached to the tree were exposed to one of three concentrations of nutrient solutions for time periods ranging from 1 to 96 hours, and solutions were analyzed for ammonium,more » nitrate, calcium, magnesium, and potassium. Surprisingly, the two species were indistinguishable in nutrient uptake within site for all nutrients (P > 0.25), but uptake rates differed by site. In general, nutrient uptake was higher at Fraser (P = 0.01, 0.15, 0.03, 0.18 for NH{sub 4}{sup +}, NO{sub 3}{sup -}, Ca{sup 2+}, and K{sup +}, respectively), which is west of the Continental Divide and has lower atmospheric deposition of N than Loch Vale. Mean uptake rates by site for ambient solution concentrations were 0.12 {micro}mol NH{sub 4}{sup +} g{sub fwt}{sup -1} h{sup -1}, 0.02 {micro}mol NO{sub 3}{sup -} g{sub fwt}{sup -1}, 0.21 {micro}mol Ca{sup 2+} g{sub fwt}{sup -1} h{sup -1}, and 0.01 {micro}mol Mg{sup 2+} g{sub fwt}{sup -1} h{sup -1} at Loch Vale, and 0.21 {micro}mol NH{sub 4}{sup +} f{sub fwt}{sup -1}h{sup -1}, 0.04 {micro}mol NO{sub 3}{sup -} g{sub fwt}{sup -1} h{sup -1}, 0.51 {micro}mol Ca{sup 2+}g{sub fwt}{sup -1}h{sup -1}, and 0.07 {micro}mol Mg{sup 2+} f{sub fwt}{sup -1}h{sup -1} at Fraser. The importance of site conditions in determining uptake capacity should not be overlooked when parameterizing nutrient uptake models. We also characterized the root morphology of these two species and compared them to other tree species we have measured at various sites in the northeastern USA. Engelman spruce and subalpine fir were indistinguishable in specific root length and diameter distribution, while most of the other ten species had statistically distinct diameter distributions across five diameter classes < 2 mm. Based on specific root length, subalpine fir and Engelmann spruce had significantly coarser roots than red pine (Pinus resinosa Soland), yellow birch (Betula allegheniensis Britt.), sugar maple (Acer saccharum Marsh.), chestnut oak (Quercus prinus L.), black cherry (Prunus serotina Ehrh.), and red spruce (Picea rubens Sarg.). White oak (Quercus alba L.), balsam fir (Abies balsamea (L.) Mill.), American beech (Fagus grandifolia Ehrh.) and loblolly pine (Pinus taeda L.) were intermediate in SRL (indistinguishable from Engelmann spruce and subalpine fir by ANOVA). Species that differ more in physiology and morphology than the two species we compared would likely show dissimilar uptake characteristics even at the same site.« less

Estimated dose rates to members of the public from external exposure to patients with {sup 131}I thyroid treatment

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

Dewji, S., E-mail: dewjisa@ornl.gov; Bellamy, M.; Leggett, R.

Purpose: Estimated dose rates that may result from exposure to patients who had been administered iodine-131 ({sup 131}I) as part of medical therapy were calculated. These effective dose rate estimates were compared with simplified assumptions under United States Nuclear Regulatory Commission Regulatory Guide 8.39, which does not consider body tissue attenuation nor time-dependent redistribution and excretion of the administered {sup 131}I. Methods: Dose rates were estimated for members of the public potentially exposed to external irradiation from patients recently treated with {sup 131}I. Tissue attenuation and iodine biokinetics were considered in the patient in a larger comprehensive effort to improvemore » external dose rate estimates. The external dose rate estimates are based on Monte Carlo simulations using the Phantom with Movable Arms and Legs (PIMAL), previously developed by Oak Ridge National Laboratory and the United States Nuclear Regulatory Commission. PIMAL was employed to model the relative positions of the {sup 131}I patient and members of the public in three exposure scenarios: (1) traveling on a bus in a total of six seated or standing permutations, (2) two nursing home cases where a caregiver is seated at 30 cm from the patient’s bedside and a nursing home resident seated 250 cm away from the patient in an adjacent bed, and (3) two hotel cases where the patient and a guest are in adjacent rooms with beds on opposite sides of the common wall, with the patient and guest both in bed and either seated back-to-back or lying head to head. The biokinetic model predictions of the retention and distribution of {sup 131}I in the patient assumed a single voiding of urinary bladder contents that occurred during the trip at 2, 4, or 8 h after {sup 131}I administration for the public transportation cases, continuous first-order voiding for the nursing home cases, and regular periodic voiding at 4, 8, or 12 h after administration for the hotel room cases. Organ specific activities of {sup 131}I in the thyroid, bladder, and combined remaining tissues were calculated as a function of time after administration. Exposures to members of the public were considered for {sup 131}I patients with normal thyroid uptake (peak thyroid uptake of ∼27% of administered {sup 131}I), differentiated thyroid cancer (DTC, 5% uptake), and hyperthyroidism (80% uptake). Results: The scenario with the patient seated behind the member of the public yielded the highest dose rate estimate of seated public transportation exposure cases. The dose rate to the adjacent room guest was highest for the exposure scenario in which the hotel guest and patient are seated by a factor of ∼4 for the normal and differentiated thyroid cancer uptake cases and by a factor of ∼3 for the hyperthyroid case. Conclusions: It was determined that for all modeled cases, the DTC case yielded the lowest external dose rates, whereas the hyperthyroid case yielded the highest dose rates. In estimating external dose to members of the public from patients with {sup 131}I therapy, consideration must be given to (patient- and case-specific) administered {sup 131}I activities and duration of exposure for a more complete estimate. The method implemented here included a detailed calculation model, which provides a means to determine dose rate estimates for a range of scenarios. The method was demonstrated for variations of three scenarios, showing how dose rates are expected to vary with uptake, voiding pattern, and patient location.« less

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.

Measuring oxygen uptake in fishes with bimodal respiration.

PubMed

Lefevre, S; Bayley, M; McKenzie, D J

2016-01-01

Respirometry is a robust method for measurement of oxygen uptake as a proxy for metabolic rate in fishes, and how species with bimodal respiration might meet their demands from water v. air has interested researchers for over a century. The challenges of measuring oxygen uptake from both water and air, preferably simultaneously, have been addressed in a variety of ways, which are briefly reviewed. These methods are not well-suited for the long-term measurements necessary to be certain of obtaining undisturbed patterns of respiratory partitioning, for example, to estimate traits such as standard metabolic rate. Such measurements require automated intermittent-closed respirometry that, for bimodal fishes, has only recently been developed. This paper describes two approaches in enough detail to be replicated by the interested researcher. These methods are for static respirometry. Measuring oxygen uptake by bimodal fishes during exercise poses specific challenges, which are described to aid the reader in designing experiments. The respiratory physiology and behaviour of air-breathing fishes is very complex and can easily be influenced by experimental conditions, and some general considerations are listed to facilitate the design of experiments. Air breathing is believed to have evolved in response to aquatic hypoxia and, probably, associated hypercapnia. The review ends by considering what realistic hypercapnia is, how hypercapnic tropical waters can become and how this might influence bimodal animals' gas exchange. © 2015 The Fisheries Society of the British Isles.

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.

Simulating and explaining passive air sampling rates for semi-volatile compounds on polyurethane foam passive samplers

PubMed Central

Petrich, Nicholas T.; Spak, Scott N.; Carmichael, Gregory R.; Hu, Dingfei; Martinez, Andres; Hornbuckle, Keri C.

2013-01-01

Passive air samplers (PAS) including polyurethane foam (PUF) are widely deployed as an inexpensive and practical way to sample semi-volatile pollutants. However, concentration estimates from PAS rely on constant empirical mass transfer rates, which add unquantified uncertainties to concentrations. Here we present a method for modeling hourly sampling rates for semi-volatile compounds from hourly meteorology using first-principle chemistry, physics, and fluid dynamics, calibrated from depuration experiments. This approach quantifies and explains observed effects of meteorology on variability in compound-specific sampling rates and analyte concentrations; simulates nonlinear PUF uptake; and recovers synthetic hourly concentrations at a reference temperature. Sampling rates are evaluated for polychlorinated biphenyl congeners at a network of Harner model samplers in Chicago, Illinois during 2008, finding simulated average sampling rates within analytical uncertainty of those determined from loss of depuration compounds, and confirming quasi-linear uptake. Results indicate hourly, daily and interannual variability in sampling rates, sensitivity to temporal resolution in meteorology, and predictable volatility-based relationships between congeners. We quantify importance of each simulated process to sampling rates and mass transfer and assess uncertainty contributed by advection, molecular diffusion, volatilization, and flow regime within the PAS, finding PAS chamber temperature contributes the greatest variability to total process uncertainty (7.3%). PMID:23837599

Monosaccharide uptake by erythrocytes of the embryonic and adult chicken.

PubMed

Ingermann, R L; Stock, M K; Metcalfe, J; Bissonnette, J M

1985-01-01

Rates of monosaccharide uptake by adult and 10-18 day old embryonic chicken erythrocytes were quantitated. The rate of carrier-mediated, stereospecific transport decreased 28% from day 10 to day 14 of incubation and was unchanged thereafter. At no time, however, did the rate of carrier-mediated transport by embryonic erythrocytes differ significantly from that of the adult cells. The rate of transfer by simple diffusion was 3-5 fold faster in embryonic than in adult erythrocytes. Uptake by simple diffusion decreased slightly as the embryo developed. Chronic hyperoxic incubation (70% O2) had little influence on total monosaccharide uptake by embryonic erythrocytes.

The significance of respiration timing in the energetics estimates of free-ranging killer whales (Orcinus orca).

PubMed

Roos, Marjoleine M H; Wu, Gi-Mick; Miller, Patrick J O

2016-07-01

Respiration rate has been used as an indicator of metabolic rate and associated cost of transport (COT) of free-ranging cetaceans, discounting potential respiration-by-respiration variation in O2 uptake. To investigate the influence of respiration timing on O2 uptake, we developed a dynamic model of O2 exchange and storage. Individual respiration events were revealed from kinematic data from 10 adult Norwegian herring-feeding killer whales (Orcinus orca) recorded with high-resolution tags (DTAGs). We compared fixed O2 uptake per respiration models with O2 uptake per respiration estimated through a simple 'broken-stick' O2-uptake function, in which O2 uptake was assumed to be the maximum possible O2 uptake when stores are depleted or maximum total body O2 store minus existing O2 store when stores are close to saturated. In contrast to findings assuming fixed O2 uptake per respiration, uptake from the broken-stick model yielded a high correlation (r(2)>0.9) between O2 uptake and activity level. Moreover, we found that respiration intervals increased and became less variable at higher swimming speeds, possibly to increase O2 uptake efficiency per respiration. As found in previous studies, COT decreased monotonically versus speed using the fixed O2 uptake per respiration models. However, the broken-stick uptake model yielded a curvilinear COT curve with a clear minimum at typical swimming speeds of 1.7-2.4 m s(-1) Our results showed that respiration-by-respiration variation in O2 uptake is expected to be significant. And though O2 consumption measurements of COT for free-ranging cetaceans remain impractical, accounting for the influence of respiration timing on O2 uptake will lead to more consistent predictions of field metabolic rates than using respiration rate alone. © 2016. Published by The Company of Biologists Ltd.

Characterizing roots and water uptake in a ground cover rice production system

PubMed Central

Li, Sen; Zuo, Qiang; Wang, Xiaoyu; Ma, Wenwen; Jin, Xinxin; Shi, Jianchu; Ben-Gal, Alon

2017-01-01

Background and aims Water-saving ground cover rice production systems (GCRPS) are gaining popularity in many parts of the world. We aimed to describe the characteristics of root growth, morphology, distribution, and water uptake for a GCRPS. Methods A traditional paddy rice production system (TPRPS) was compared with GCRPS in greenhouse and field experiments. In the greenhouse, GCRPS where root zone average soil water content was kept near saturation (GCRPSsat), field capacity (GCRPSfwc) and 80% field capacity (GCRPS80%), were evaluated. In a two-year field experiment, GCRPSsat and GCRPS80% were applied. Results Similar results were found in greenhouse and field experiments. Before mid-tillering the upper soil temperature was higher for GCRPS, leading to enhanced root dry weight, length, surface area, specific root length, and smaller diameter of roots but lower water uptake rate per root length compared to TPRPS. In subsequent growth stages, the reduced soil water content under GCRPS caused that the preponderance of root growth under GCRPSsat disappeared in comparison to TPRPS. Under other GCRPS treatments (GCRPSfwc and GCRPS80%), significant limitation on root growth, bigger root diameter and higher water uptake rate per root length were found. Conclusions Discrepancies in soil water and temperature between TPRPS and GCRPS caused adjustments to root growth, morphology, distribution and function. Even though drought stress was inevitable after mid-tillering under GCRPS, especially GCRPS80%, similar or even enhanced root water uptake capacity in comparison to TPRPS might promote allocation of photosynthetic products to shoots and increase water productivity. PMID:28686687

Factors Determining the Uptake of Influenza Vaccination Among Children With Chronic Conditions.

PubMed

Chau, Janita Pak Chun; Lo, Suzanne Hoi Shan; Choi, Kai Chow; Chau, Matthew Hoi Kin; Tong, Danny Wah Kun; Kwong, Tany Kam Yuk; Thompson, David R

2017-07-01

Studies report that the influenza vaccination uptake rate among children with chronic conditions is alarmingly low. In Hong Kong, there has been no study examining parental decision making about influenza vaccination for children with chronic conditions, thereby limiting the knowledge base to inform the development of specific strategies to improve influenza vaccination rates. The aim of this study was to identify factors determining the uptake of influenza vaccination among children with chronic conditions. We conducted a cross-sectional survey of 623 parents with children having a chronic condition recruited from pediatric wards and specialty outpatient departments of 2 acute hospitals. A questionnaire developed by Daley et al based on the Health Belief Model was used to examine parents' beliefs and attitudes toward influenza and vaccination. The parents' and their children's mean age were 40.1 ± 8.1 and 8.0 ± 4.5 years, respectively. Among the children, the most prevalent chronic conditions were asthma, chronic respiratory disease and cardiomyopathy. One-third (33%) of the children had influenza vaccination in the past 12 months. More than one-third (39%) of parents intended to vaccinate their children against influenza in the coming influenza season. A multivariable logistic regression analysis revealed that all subscale scores except perceived severity and knowledge about influenza were independently significantly associated with uptake. The findings indicate that parents of children with chronic conditions lack awareness of the risks of influenza and have insufficient understanding about the benefits of vaccination. These findings could inform the development of interventions to promote vaccination uptake among children with chronic conditions.

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.

Regulation of the Na+2Cl–K+ cotransporter in in vitro perfused rectal gland tubules of Squalus acanthias.

PubMed

Warth, R; Bleich, M; Thiele, I; Lang, F; Greger, R

1998-07-01

Previously it has been shown that the Na+2Cl–K+ cotransporter accepts NH4 + at its K+ binding site. This property can be used to estimate its transport rates by adding NH4 + to the bath and measuring the initial furosemide-dependent rates of change in BCECF fluorescence. We have utilized this technique to determine the regulation of the furosemide-inhibitable Na+2Cl–K+ cotransporter in in vitroperfused rectal gland tubules (RGT) of Squalus acanthias. Addition of NH4 + to the bath (20 mmol/l) led to an initial alkalinization, corresponding to NH3 uptake. This was followed by an acidification, corresponding to NH4 + uptake. The rate of this uptake was quantified by exponential curve fitting and is given in arbitrary units (Δfluorescence/time). This acidification could be completely inhibited by furosemide. In the absence of any secretagogue preincubation of RGT in a low Cl– solution (6 mmol/l, low Cl–) for 10 min enhanced the uptake rate significantly from 4.04±0.51 to 12.7±1.30 (n=5). The addition of urea (200 mmol/l) was without effect, but the addition of 300 mmol/l mannitol (+300 mannitol) enhanced the rate significantly from 7.24±1.33 to 14.7±4.6 (n=6). Stimulation of NaCl secretion by a solution maximizing the cytosolic cAMP concentration (Stim) led to a significant increase in NH4 + uptake rate from 5.00±1.33 to 13.3±1.54 (n=6). Similar results were obtained in the additional presence of Ba2+ (1 mmol/l): the uptake rate was increased significantly from 4.23±0.34 to 15.1±1.86 (n=16). In the presence of Stim low Cl– had no additional effect on the uptake rate: 15.1±3.1 versus 15.2±2.8 in high Cl– (n=6). The uptake rate in Stim containing additional +300 mannitol (22.3±4.0, n=5) was not significantly different from that obtained with Stim or +300 mannitol alone. By whatever mechanism the NH4 + uptake rate was increased furosemide (500 µmol/l) always reduced this rate to control values. Hence three manoeuvres enhanced furosemide-inhibitable uptake rates of the Na+2Cl–K+ cotransporter probably independently: (1) lowering of cytosolic Cl– concentration; (2) cell shrinkage; and (3) activation by cAMP.

Nitrate removal rates change over time during tracer tests: towards zone specific reaction rates and watershed budgets.

NASA Astrophysics Data System (ADS)

Aubeneau, A. F.; Ghassani, A. F.; Avilar, C.; Xiong, X.; Wang, S.

2016-12-01

Fertilizer pollution leading to downstream eutrofication and hypoxia is a grand challenge affecting aquatic ecosystems and human activities. Here, we present numerical and experimental results showing that simple tracer tests can provide sufficient data to disentangle the contribution of the water column, the benthic zone and the hyporheic zone to total nitrate uptake at the reach scale. The processes that drive nitrate removal are very different in these three distinct environments and their relative contribution change along the river continuum. The dark, often hypoxic hyporheic zone is where denitrification takes place, while autotrophs temporarily store nitrogen in their biomass in the benthos or the water column. The contribution of pelagic uptake increases downstream as rivers are deeper and slower. Together, these findings can be gathered to empirically inform watershed models and arrive at better nutrient budgets and water quality predictions.

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.

Fluorodeoxyglucose--positive internal mammary lymph node in breast cancer patients with silicone implants: is it always metastatic cancer?

PubMed

Soudack, Michalle; Yelin, Alon; Simansky, David; Ben-Nun, Alon

2013-07-01

Patients with breast cancer following mastectomy and silicone implant reconstruction may have enlarged internal mammary lymph nodes with pathological uptake on positron emission tomography with (18)F-fluorodeoxyglucose. This lymphadenopathy is usually considered as metastatic in nature, but has also been reported to be related to other conditions, including silicon migration. The purpose of this study was to determine the rate of metastatic disease in this unique group of patients. A retrospective comparative study of 12 female patients with breast cancer with silicone implants referred for biopsy due to isolated internal mammary lymph node fluorodeoxyglucose uptake on positron emission tomography. Five patients (41.6%) had histological findings related to silicone (n = 4) or non-specific inflammation (n = 1). The remaining 7 (58.3%) had histological evidence of cancer recurrence. There was no significant difference in the fluorodeoxyglucose-standardized uptake value between the two groups. Fluorodeoxyglucose-positive mammary lymph nodes in patients with breast cancer following silicone implant reconstruction may be due to metastatic deposits, non-specific inflammation or silicone migration. Clinical and imaging characteristics are insufficient in differentiating between these conditions. Biopsy is recommended prior to initiation of further treatment.

A five-year study of the impact of nitrogen addition on methane uptake in alpine grassland.

PubMed

Yue, Ping; Li, Kaihui; Gong, Yanming; Hu, Yukun; Mohammat, Anwar; Christie, Peter; Liu, Xuejun

2016-08-30

It remains unclear how nitrogen (N) deposition affects soil methane (CH4) uptake in semiarid and arid zones. An in situ field experiment was conducted from 2010 to 2014 to systematically study the effect of various N application rates (0, 10, 30, and 90 kg N ha(-1) yr(-1)) on CH4 flux in alpine grassland in the Tianshan Mountains. No significant influence of N addition on CH4 uptake was found. Initially the CH4 uptake rate increased with increasing N application rate by up to 11.5% in 2011 and then there was gradual inhibition by 2014. However, the between-year variability in CH4 uptake was very highly significant with average uptake ranging from 52.9 to 106.6 μg C m(-2) h(-1) and the rate depended largely on seasonal variability in precipitation and temperature. CH4 uptake was positively correlated with soil temperature, air temperature and to a lesser extent with precipitation, and was negatively correlated with soil moisture and NO3(-)-N content. The results indicate that between-year variability in CH4 uptake was impacted by precipitation and temperature and was not sensitive to elevated N deposition in alpine grassland.

A five-year study of the impact of nitrogen addition on methane uptake in alpine grassland

PubMed Central

Yue, Ping; Li, Kaihui; Gong, Yanming; Hu, Yukun; Mohammat, Anwar; Christie, Peter; Liu, Xuejun

2016-01-01

It remains unclear how nitrogen (N) deposition affects soil methane (CH4) uptake in semiarid and arid zones. An in situ field experiment was conducted from 2010 to 2014 to systematically study the effect of various N application rates (0, 10, 30, and 90 kg N ha−1 yr−1) on CH4 flux in alpine grassland in the Tianshan Mountains. No significant influence of N addition on CH4 uptake was found. Initially the CH4 uptake rate increased with increasing N application rate by up to 11.5% in 2011 and then there was gradual inhibition by 2014. However, the between-year variability in CH4 uptake was very highly significant with average uptake ranging from 52.9 to 106.6 μg C m−2 h−1 and the rate depended largely on seasonal variability in precipitation and temperature. CH4 uptake was positively correlated with soil temperature, air temperature and to a lesser extent with precipitation, and was negatively correlated with soil moisture and NO3−-N content. The results indicate that between-year variability in CH4 uptake was impacted by precipitation and temperature and was not sensitive to elevated N deposition in alpine grassland. PMID:27571892

Retention Kinetics of the 18F-Labeled Sympathetic Nerve PET Tracer LMI1195: Comparison with 11C-Hydroxyephedrine and 123I-MIBG.

PubMed

Werner, Rudolf A; Rischpler, Christoph; Onthank, David; Lapa, Constantin; Robinson, Simon; Samnick, Samuel; Javadi, Mehrbod; Schwaiger, Markus; Nekolla, Stephan G; Higuchi, Takahiro

2015-09-01

(18)F-N-[3-bromo-4-(3-fluoro-propoxy)-benzyl]-guanidine ((18)F-LMI1195) is a new PET tracer designed for noninvasive assessment of sympathetic innervation of the heart. The (18)F label facilitates the imaging advantages of PET over SPECT technology while allowing centralized manufacturing. Highly specific neural uptake of (18)F-LMI1195 has previously been established, but the retention kinetics are not yet fully understood. Healthy New Zealand White rabbits were studied with (18)F-LMI1195 using a small-animal PET system. Dynamic 40-min chest scans were started just before intravenous bolus injection of (18)F-LMI1195. Imaging was performed under norepinephrine transport inhibition with desipramine pretreatment, a 1.5 mg/kg desipramine chase administered 10 min after tracer injection, and saline treatment of controls. As a reference, cardiac uptake of (11)C-hydroxyephedrine and (123)I-metaiodobenzylguanidine ((123)I-MIBG) was examined by PET and planar scintigraphy, respectively. Cardiac uptake of all 3 tracers was inhibited by pretreatment with desipramine. Stable cardiac tracer retention was delineated by dynamic PET in control rabbits for (11)C-hydroxyephedrine (washout rate, 0.42% ± 0.57%/min) and (18)F-LMI1195 (washout rate, 0.058% ± 0.28%/min). A desipramine chase increased (11)C-hydroxyephedrine washout from the heart (2.43% ± 0.15%/min, P < 0.001), whereas (18)F-LMI1195 washout was not influenced (0.059% ± 0.11%/min, not statistically significant). Additionally, a desipramine chase did not change the cardiac (123)I-MIBG uptake (delayed heart-to-mediastinum ratio, 1.99 ± 0.12 (desipramine chase) vs. 2.05 ± 0.16 (controls), not statistically significant). In vivo norepinephrine transporter (NET) blockade with desipramine confirmed specific neural uptake of (18)F-LMI1195, (11)C-hydroxyephedrine, and (123)I-MIBG in rabbit hearts. (11)C-hydroxyephedrine cardiac retention was sensitive to a NET inhibitor chase, indicating a cycle of continuous NET uptake and release at the nerve terminals. In contrast, (18)F-LMI1195 and (123)I-MIBG demonstrated stable storage at the nerve terminal with resistance to a NET inhibitor chase, mimicking physiologic norepinephrine turnover. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Lacrimal gland uptake of (67)Ga-gallium citrate correlates with biopsy results in patients with suspected sarcoidosis.

PubMed

Tannen, Bradford L; Kolomeyer, Anton M; Turbin, Roger E; Frohman, Larry; Langer, Paul D; Oh, Cheongeun; Ghesani, Nasrin V; Zuckier, Lionel S; Chu, David S

2014-02-01

To investigate whether lacrimal gland uptake on (67)Ga-gallium citrate scintigraphy correlates with histopathologic evidence of sarcoidosis. A retrospective, pilot study of 31 patients with suspected sarcoidosis who underwent gallium scintigraphy and lacrimal gland biopsy. Lacrimal gland gallium uptake was assessed by subjective visual scoring (SVS) and lacrimal uptake ratio (LUR). Eleven (36%) patients had lacrimal gland biopsies containing noncaseating granulomas. A statistically significant correlation was found between lacrimal gland gallium uptake and biopsy positivity using SVS (p = 0.03) or LUR (p = 0.01). Using SVS, biopsy positivity rate increased from 0 to 50% in patients with mild to intense uptake. Using LUR, biopsy positivity rate increased linearly as the ratio increased from 13% (LUR < 4) to 100% (LUR > 8). Lacrimal biopsy positivity rate significantly correlated with gallium uptake on scintigraphy. Both SVS and LUR methods appear to correlate with histologic results and may potentially aid in patient selection for biopsy.

Influence of body size, metabolic rate and life history stage on the uptake and excretion of the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) by invasive sea lampreys (Petromyzon marinus).

PubMed

Tessier, Laura R; Long, Tristan A F; Wilkie, Michael P

2018-01-01

Invasive sea lamprey (Petromyzon marinus) are controlled in the Great Lakes using the lampricide 3-trifluoromethyl-4-nitrophenol (TFM), which is applied to streams infested with larval lamprey. However, lamprey that survive treatments (residuals) remain a challenge because they may subsequently undergo metamorphosis into parasitic juvenile animals that migrate downstream to the Great Lakes, where they feed on important sport and commercial fishes. The goal of this study was to determine if body size and life stage could potentially influence sea lamprey tolerance to TFM by influencing patterns of TFM uptake and elimination. Because mass specific rates of oxygen consumption (M˙O 2 ) are lower in larger compared to smaller lamprey, we predicted that TFM uptake would be negatively correlated to body size, suggesting that large larvae would be more tolerant to TFM exposure. Accordingly, TFM uptake and M˙O 2 were measured in larvae ranging in size from 0.2-4.2g using radio-labelled TFM ( 14 C-TFM) and static respirometry. Both were inversely proportional to wet mass (M), and could be described usingthe allometric power relationship: Y=aM b , in which M˙O 2 =1.86M 0.53 and TFM Uptake=7.24M 0.34 . We also predicted that body size would extend to rates of TFM elimination, which was measured following the administration of 14 C-TFM (via intraperitoneal injection). However, there were no differences in the half-lives of elimination of TFM (T 1/2 -TFM). There were also no differences in M˙O 2 or TFM uptake amongst size-matched larval, metamorphosing (stages 6-7), or post-metamorphic (juvenile) sea lamprey. However, the T 1/2 -TFM was significantly lower in larval than post-metamorphic lamprey (juvenile), indicating the larval lamprey cleared TFM more efficiently than juvenile lamprey. We conclude that larger larval sea lamprey are more likely to survive TFM treatments suggesting that body size might be an important variable to consider when treating streams with TFM to control these invasive species. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Cell line-dependent differences in uptake and retention of the hypoxia-selective nuclear imaging agent Cu-ATSM.

PubMed

Burgman, Paul; O'Donoghue, Joseph A; Lewis, Jason S; Welch, Michael J; Humm, John L; Ling, C Clifton

2005-08-01

Cu-diacetyl-bis(N(4)-methylthiosemicarbazone) [Cu-ATSM] is a potential marker for tumor hypoxia that has been under evaluation for clinical use. In this study, we examined the mechanisms underlying the uptake of (64)Cu in cells incubated with (64)Cu-ATSM. The in vitro uptake of (64)Cu was determined as a function of oxygenation conditions and incubation time with (64)Cu-ATSM using four and two tumor cell lines of human origin and rodent origin, respectively. Additionally, the rate of (64)Cu efflux and Cu-ATSM metabolism was determined. (64)Cu accumulation is rapid during the first 0.5-1 h of incubation. It is highest in anoxic cells but is also significant in normoxic cells. After this initial period, the level of intracellular (64)Cu varies depending on the cell line and the oxygenation conditions and, in some circumstances, may decrease. During the first 0.5-1 h, the ratio of (64)Cu levels between anoxic and normoxic cells is approximately 2:10 and that between hypoxic (0.5% O(2)) and normoxic cells is approximately 1:2.5, depending on the cell line. These ratios generally decrease at longer times. The (64)Cu-ATSM compound was found to be metabolized during incubation in a manner dependent on oxygenation conditions. Within 2 h under anoxic conditions, (64)Cu-ATSM could no longer be detected, although 60-90% of the amount of (64)Cu added as (64)Cu-ATSM was present in the medium. Non-ATSM (64)Cu was taken up by the cells, albeit at a much slower rate. Efflux rates of (64)Cu were found to be cell line dependent and appeared to be inversely correlated with the final (64)Cu uptake levels under anoxic conditions. The uptake and retention of (64)Cu and their relation to oxygenation conditions were found to be cell line dependent. Given the complexities in the oxygen dependence and cell line-dependent kinetics of uptake and retention of Cu following exposure to Cu-ATSM, the clinical utility of this compound may be disease site specific.

Taurine transport across hepatocyte plasma membranes: analysis in isolated rat liver sinusoidal plasma membrane vesicles.

PubMed

Inoue, M; Arias, I M

1988-07-01

To elucidate the mechanism of taurine transport across the hepatic plasma membranes, rat liver sinusoidal plasma membrane vesicles were isolated and the transport process was analyzed. In the presence of a sodium gradient across the membranes (vesicle inside less than vesicle outside), an overshooting uptake of taurine occurred. In the presence of other ion gradients (K+, Li+, and choline+), taurine uptake was very small and no such overshoot was observed. Sodium-dependent uptake of taurine occurred into an osmotically active intravesicular space. Taurine uptake was stimulated by preloading vesicles with unlabeled taurine (transstimulation) in the presence of NaCl, but not in the presence of KCl. Sodium-dependent transport followed saturation kinetics with respect to taurine concentration; double-reciprocal plots of uptake versus taurine concentration gave a straight line from which an apparent Km value of 0.38 mM and Vmax of 0.27 nmol/20 s x mg of protein were obtained. Valinomycin-induced K+-diffusion potential failed to enhance the rate of taurine uptake, suggesting that taurine transport does not depend on membrane potential. Taurine transport was inhibited by structurally related omega-amino acids, such as beta-alanine and gamma-aminobutyric acid, but not by glycine, epsilon-aminocaproic acid, or other alpha-amino acids, such as L-alanine. These results suggest that Na+-dependent uptake of taurine might occur across the hepatic sinusoidal plasma membranes via a transport system that is specific for omega-amino acids having 2-3 carbon chain length.

Plant traits related to nitrogen uptake influence plant-microbe competition.

PubMed

Moreau, Delphine; Pivato, Barbara; Bru, David; Busset, Hugues; Deau, Florence; Faivre, Céline; Matejicek, Annick; Strbik, Florence; Philippot, Laurent; Mougel, Christophe

2015-08-01

Plant species are important drivers of soil microbial communities. However, how plant functional traits are shaping these communities has received less attention though linking plant and microbial traits is crucial for better understanding plant-microbe interactions. Our objective was to determine how plant-microbe interactions were affected by plant traits. Specifically we analyzed how interactions between plant species and microbes involved in nitrogen cycling were affected by plant traits related to 'nitrogen nutrition in interaction with soil nitrogen availability. Eleven plant species, selected along an oligotrophic-nitrophilic gradient, were grown individually in a nitrogen-poor soil with two levels of nitrate availability. Plant traits for both carbon and nitrogen nutrition were measured and the genetic structure and abundance of rhizosphere. microbial communities, in particular the ammonia oxidizer and nitrate reducer guilds, were analyzed. The structure of the bacterial community in the rhizosphere differed significantly between plant species and these differences depended on nitrogen availability. The results suggest that the rate of nitrogen uptake per unit of root biomass and per day is a key plant trait, explaining why the effect of nitrogen availability on the structure of the bacterial community depends on the plant species. We also showed that the abundance of nitrate reducing bacteria always decreased with increasing nitrogen uptake per unit of root biomass per day, indicating that there was competition for nitrate between plants and nitrate reducing bacteria. This study demonstrates that nitrate-reducing microorganisms may be adversely affected by plants with a high nitrogen uptake rate. Our work puts forward the role of traits related to nitrogen in plant-microbe interactions, whereas carbon is commonly considered as the main driver. It also suggests that plant traits related to ecophysiological processes, such as nitrogen uptake rates, are more relevant for understanding plant-microbe interactions than composite traits, such as nitrophily, which are related to a number of ecophysiological processes.

Physiological effects of a new racing suit for elite cross country skiers.

PubMed

Sperlich, B; Holmberg, H C

2011-12-01

The aim of this paper was to investigate the influence of the new cross country racing suit, designed for the Olympic Winter Games in Vancouver 2010, on cardio-respiratory, thermoregulatory and perceptual responses. Six elite cross country skiers (29±6 years, peak oxygen uptake 73.2±6.9 mL·min-1·kg-1) performed two exercise bouts wearing either the 2009 or the 2010 racing suit. Bouts consisted of incremental testing on roller skis (12 km·h-1 at 5° inclination; 11 km·h-1 at 6° inclination and 12 km·h-1at 8° inclination for six minutes). During increasing intensities, significantly lower values were found for oxygen uptake, minute ventilation, RER and heart rate when wearing the new suit compared to the old one (P<0.05; effect sizes: 0.21-4.00). Core temperature was lower with the new suit during steps 2 and 3 (P<0.05, effect size: 1.22-1.27). Also, mean skin temperature was lower during the last increment (P<0.05, effect size: 0.87). The new 2010 racing suit, developed specifically for the Olympic Winter Games in Vancouver 2010, demonstrated lower values for oxygen uptake, minute ventilation, heart rate, skin and core temperature, ratings of thermal and sweat sensation when compared to the 2009 racing suit.

Specific stimulated uptake of acetylcholine by Torpedo electric organ synaptic vesicles.

PubMed Central

Parsons, S M; Koenigsberger, R

1980-01-01

The specificity of acetylcholine uptake by synaptic vesicles isolated from the electric organ of Torpedo californica was studied. In the absence of cofactors, [3H]acetylcholine was taken up identically to[14C]choline in the same solution (passive uptake), and the equilibrium concentration achieved inside the vesicles was equal to the concentration outside. In the presence of MgATP, [3H]acetylcholine and [14C]choline in the same solution were taken up identically, except only about half as much of each was taken up (suppressed uptake). [3H]Acetylcholine uptake was stimulated by MgATP and HCO3- about 4-fold relative to suppressed uptake, for a net concentrative uptake of about 2:1 (stimulated uptake). Uptake of [14C]choline in the same solution remained at the suppressed level. [3H]Acetylcholine taken up under stimulated conditions migrated with vesicles containing [14C]mannitol on analytical glycerol density gradients during centrifugation. Vesicle were treated with nine protein modification reagents under mild conditions. Two reagents had no effect on, dithiothreitol potentiated, and six reagents strongly inhibited subsequent stimulated uptake of [3H]acetylcholine. The results indicate that uptake of acetylcholine is conditionally specific for the transported substrate, is carried out by the synaptic vesicles rather than a contaminant of the preparation, and requires a functional protein system containing a critical sulfhydryl group. PMID:6934549

Comparative Physiological Studies of the Yeast and Mycelial Forms of Histoplasma capsulatum: Uptake and Incorporation of l-Leucine

PubMed Central

Gupta, Rishab K.; Howard, Dexter H.

1971-01-01

l-Leucine entered the cells of both morphological forms of Histoplasma capsulatum by a permease-like system at low external concentrations of substrate. However, at levels greater than 5 × 10−5m l-leucine, the amino acid entered the cells both through a simple diffusion-like process and the permease-like system. The rate of the amino acid diffusion into yeast and mycelial forms appeared to be the same, whereas the initial rate of accumulation through the permease-like system was 5 to 10 times faster in the mycelial phase than it was in the yeast phase. The Michaelis constants were 2.2 × 10−5m in yeast phase and 2 × 10−5m in mycelial phase cells. Transport of l-leucine at an external concentration of 10−5m showed all of the characteristics of a system of active transport, which was dependent on temperature and pH. Displacement or removal of the α-amino group, or modification of the α-carboxyl group abolished amino acid uptake. The process was competitively inhibited by neutral aliphatic side-chain amino acids (inhibition constants ranged from 1.5 × 10−5 to 6.2 × 10−5m). Neutral aromatic side-chain amino acids and the d-isomers of leucine and valine did not inhibit l-leucine uptake. These data were interpreted to mean that the l-leucine transport system is stereospecific and is highly specific for neutral aliphatic side-chain amino acids. Incorporation of l-leucine into macromolecules occurred at almost the same rate in both morphological forms of the fungus. The mycelial phase but not the yeast phase showed a slight initial lag in incorporation. In both morphological forms the intracellular pool of l-leucine was of limited capacity, and the total uptake of the amino acid was a function of intracellular pool size. The initial rate of l-leucine uptake was independent of the level of intracellular pool. Both morphological forms deaminated and degraded only a minor fraction of the accumulated leucine. PMID:4323295

( sup 14 C)-Sucrose uptake by guard cell protoplasts of pisum sativum, argenteum mutant

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

Rohrig, K.; Raschke, K.

1991-05-01

Guard cells rely on import for their supply with reduced carbon. The authors tested by silicone oil centrifugation the ability of guard cell protoplasts to accumulated ({sup 14}C)-sucrose. Uptake rates were corrected after measurement of {sup 14}C-sorbitol and {sup 3}H{sub 2}O spaces. Sucrose uptake followed biphasic kinetics, with a high-affinity component below 1 mM external sucrose (apparent K{sub m} 0.8 mM at 25C) and a low-affinity nonsaturable component above. Uptake depended on pH (optimum at pH 5.0). Variations in the concentrations of external KCl, CCCP, and valinomycin indicated that about one-half of the sucrose uptake rate could be related tomore » an electrochemical gradient across the plasmalemma. Total uptake rates measured at 5 mM external sucrose seem to be sufficient to replenish emptied plastids with starch within a few hours.« less

Effect of cysteine and humic acids on bioavailability of Ag from Ag nanoparticles to a freshwater snail

USGS Publications Warehouse

Luoma, Samuel N.; Tasha Stoiber,; Croteau, Marie-Noele; Isabelle Romer,; Ruth Merrifeild,; Lead, Jamie

2016-01-01

Metal-based engineered nanoparticles (NPs) will undergo transformations that will affect their bioavailability, toxicity and ecological risk when released to the environment, including interactions with dissolved organic material. The purpose of this paper is to determine how interactions with two different types of organic material affect the bioavailability of silver nanoparticles (AgNPs). Silver uptake rates by the pond snail Lymnaea stagnalis were determined after exposure to 25 nmol l-1 of Ag as PVP AgNPs, PEG AgNPs or AgNO3, in the presence of either Suwannee River humic acid or cysteine, a high-affinity thiol-rich organic ligand. Total uptake rate of Ag from the two NPs was either increased or not strongly affected in the presence of 1 – 10 mg 1-1 humic acid. Humic substances contain relatively few strong ligands for Ag explaining their limited effects on Ag uptake rate. In contrast, Ag uptake rate was substantially reduced by cysteine. Three components of uptake from the AgNPs were quantified in the presence of cysteine using a biodynamic modeling approach: uptake of dissolved Ag released by the AgNPs, uptake of a polymer or large (>3kD) Ag-cysteine complex and uptake of the nanoparticle itself. Addition of 1:1 Ag:cysteine reduced concentrations of dissolved Ag, which contributed to, but did not fully explain the reductions in uptake. A bioavailable Ag-cysteine complex (> 3kD) appeared to be the dominant avenue of uptake from both PVP AgNPs and PEG AgNPs in the presence of cysteine. Quantifying the different avenues of uptake sets the stage for studies to assess toxicity unique to NPs.

Response of soil methane uptake to simulated nitrogen deposition and grazing management across three types of steppe in Inner Mongolia, China.

PubMed

Li, Xianglan; He, Hong; Yuan, Wenping; Li, Linghao; Xu, Wenfang; Liu, Wei; Shi, Huiqiu; Hou, Longyu; Chen, Jiquan; Wang, Zhiping

2018-01-15

The response of soil methane (CH 4 ) uptake to increased nitrogen (N) deposition and grazing management was studied in three types of steppe (i.e., meadow steppe, typical steppe, and desert steppe) in Inner Mongolia, China. The experiment was designed with four simulated N deposition rates such as 0, 50, 100, and 200kgNha -1 , respectively, under grazed and fenced management treatments. Results showed that the investigated steppes were significant sinks for CH 4 , with an uptake flux of 1.12-3.36kgha -1 over the grass growing season and that the magnitude of CH 4 uptake significantly (P<0.05) decreased with increasing N deposition rates. The soil CH 4 uptake rates were highest in the desert steppe, moderate in the typical steppe, and lowest in the meadow steppe. Compared with grazed plots, fencing increased the CH 4 uptake by 4.7-40.2% with a mean value of 20.2% across the three different steppe types. The responses of soil CH 4 uptake to N deposition in the continental steppe varied depending on the N deposition rate, steppe type, and grazing management. A significantly positive correlation between CH 4 uptake and soil temperature was found in this study, whereas no significant relationship between soil moisture and CH 4 uptake occurred. Our results may contribute to the improvement of model parameterization for simulating biosphere-atmosphere CH 4 exchange processes and for evaluating the climate change feedback on CH 4 soil uptake. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Mann, S.J.; Pickering, T.G.; Sos, T.A.

The purpose of this study was to determine the sensitivity, specificity, and clinical usefulness of renography performed in combination with captopril administration (captopril renography) in diagnosing renal artery stenosis. Fifty-five patients with suspected renal artery stenosis underwent renography prior to performance of renal angiography. Renography was performed on two consecutive days using technetium-99m-diethylenetiamine pentaacetic acid (DTPA) as an index of glomerular filtration rate and iodine-131-orthoiodohippurate (OIH) as an index of renal blood flow. Captopril (25 mg orally, crushed) was administered 1 hour before the second study. Renal artery stenosis was defined as a stenosis exceeding 70%. Renographic criteria were thenmore » established, retrospectively, to differentiate renal artery stenosis from essential hypertension based on (1) asymmetry of function and (2) the presence of captopril-induced changes. Renal artery stenosis was detected in 35 of 55 patients (21 with unilateral and 14 with bilateral stenosis). Three criteria were established for diagnosing renal artery stenosis: (1) a percent uptake of DTPA by the affected kidney of less than 40% of the combined bilateral uptake, (2) a delayed time to peak uptake of DTPA, which was more than 5 minutes longer in the affected kidney than in the contralateral kidney, (3) a delayed excretion of DTPA, with retention at 15 minutes, as a fraction of peak activity, more than 20% greater than in the contralateral kidney. The presence of one or more of these criteria was diagnostic of renal artery stenosis, with a sensitivity and specificity of 71% and 75%, respectively before captopril administration, and 94% and 95% after captopril administration. Lesser degrees of asymmetry (i.e., uptake of 40% to 50%) had very poor diagnostic specificity.« less

Detection and severity classification of extracardiac interference in {sup 82}Rb PET myocardial perfusion imaging

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

Orton, Elizabeth J., E-mail: eorton@physics.carleton.ca; Kemp, Robert A. de; Glenn Wells, R.

2014-10-15

Purpose: Myocardial perfusion imaging (MPI) is used for diagnosis and prognosis of coronary artery disease. When MPI studies are performed with positron emission tomography (PET) and the radioactive tracer rubidium-82 chloride ({sup 82}Rb), a small but non-negligible fraction of studies (∼10%) suffer from extracardiac interference: high levels of tracer uptake in structures adjacent to the heart which mask the true cardiac tracer uptake. At present, there are no clinically available options for automated detection or correction of this problem. This work presents an algorithm that detects and classifies the severity of extracardiac interference in {sup 82}Rb PET MPI images andmore » reports the accuracy and failure rate of the method. Methods: A set of 200 {sup 82}Rb PET MPI images were reviewed by a trained nuclear cardiologist and interference severity reported on a four-class scale, from absent to severe. An automated algorithm was developed that compares uptake at the external border of the myocardium to three thresholds, separating the four interference severity classes. A minimum area of interference was required, and the search region was limited to that facing the stomach wall and spleen. Maximizing concordance (Cohen’s Kappa) and minimizing failure rate for the set of 200 clinician-read images were used to find the optimal population-based constants defining search limit and minimum area parameters and the thresholds for the algorithm. Tenfold stratified cross-validation was used to find optimal thresholds and report accuracy measures (sensitivity, specificity, and Kappa). Results: The algorithm was capable of detecting interference with a mean [95% confidence interval] sensitivity/specificity/Kappa of 0.97 [0.94, 1.00]/0.82 [0.66, 0.98]/0.79 [0.65, 0.92], and a failure rate of 1.0% ± 0.2%. The four-class overall Kappa was 0.72 [0.64, 0.81]. Separation of mild versus moderate-or-greater interference was performed with good accuracy (sensitivity/specificity/Kappa = 0.92 [0.86, 0.99]/0.86 [0.71, 1.00]/0.78 [0.64, 0.92]), while separation of moderate versus severe interference severity classes showed reduced sensitivity/Kappa but little change in specificity (sensitivity/specificity/Kappa = 0.83 [0.77, 0.88]/0.82 [0.77, 0.88]/0.65 [0.60, 0.70]). Specificity was greater than sensitivity for all interference classes. Algorithm execution time was <1 min. Conclusions: The algorithm produced here has a low failure rate and high accuracy for detection of extracardiac interference in {sup 82}Rb PET MPI scans. It provides a fast, reliable, automated method for assessing severity of extracardiac interference.« less

Study on kinetics of glucose uptake by some species of plankton

NASA Astrophysics Data System (ADS)

Li, Wenquan; Wang, Xian; Zhang, Yaohua

1993-03-01

The rates of glucose uptake by some species of plankton were determined by3H-glucose tracer method. Experimental results indicated that the observed glucose uptake at natural seawater concentrations by Platymonas subcordiformis and Brachionus plicatilis was principally a metabolic process fitted with the Michaelis-Menten equation in the range of adaptive temperatures. Heterotrophic uptake by Platymonas subcordiformis was mainly dependent on diffusion at high glucose levels. The uptake by Brachionus plicatilis showed active transport even at high glucose levels, indicating its high heterotrophic activity. The uptake rate by Artemia salina was lower, and its V m/K ratio was lower than those of the other two species of plankton.

Kinetic control on Zn isotope signatures recorded in marine diatoms

NASA Astrophysics Data System (ADS)

Köbberich, Michael; Vance, Derek

2017-08-01

Marine diatoms dominate the oceanic cycle of the essential micronutrient zinc (Zn). The stable isotopes of zinc and other metals are increasingly used to understand trace metal micronutrient cycling in the oceans. One clear feature of the early isotope data is the heavy Zn isotope signature of the average oceanic dissolved pool relative to the inputs, potentially driven by uptake of light isotopes into phytoplankton cells and export to sediments. However, despite the fact that diatoms strip Zn from surface waters across the Antarctic polar front in the Southern Ocean, the local upper ocean is not isotopically heavy. Here we use culturing experiments to quantify the extent of Zn isotope fractionation by diatoms and to elucidate the mechanisms driving it. We have cultured two different open-ocean diatom species (T. oceanica and Chaetoceros sp.) in a series of experiments at constant medium Zn concentration but at bioavailable medium Fe ranging from limiting to replete. We find that T. oceanica can maintain high growth rates and Zn uptake rates over the full range of bioavailable iron (Fe) investigated, and that the Zn taken up has a δ66Zn that is unfractionated relative to that of the bioavailable free Zn in the medium. The studied representative of the genus Chaetoceros, on the other hand, shows more significantly reduced Zn uptake rates at low Fe and records more variable biomass δ66Zn signatures, of up to 0.85‰ heavier than the medium. We interpret the preferential uptake of heavy isotopes at extremely low Zn uptake rates as potentially due to either of the following two mechanisms. First, the release of extracellular polymeric substances (EPS), at low Fe levels, may preferentially scavenge heavy Zn isotopes. Second, the Zn uptake rate may be slow enough to establish pseudo-equilibrium conditions at the transporter site, with heavy Zn isotopes forming more stable surface complexes. Thus we find that, in our experiments, Fe-limitation exerts a key control that not only limits diatom growth, but also affects the Zn uptake physiology of diatoms. Uptake of heavy isotopes occurs under Fe-limiting conditions that drive extremely low Zn uptake rates. On the other hand, more rapid Zn uptake rates result in biomass that is indistinguishable from the external bioavailable free Zn pool. These experimental results can, in principle, explain the range of Zn isotopic compositions found in the real surface ocean, given the geographically variable interplay between Fe-limitation, Zn uptake rates, and the degree of organic complexation of oceanic Zn.

Bistability of the lac operon during growth of Escherichia coli on lactose and lactose+glucose.

PubMed

Narang, Atul; Pilyugin, Sergei S

2008-05-01

The lac operon of Escherichia coli can exhibit bistability. Early studies showed that bistability occurs during growth on TMG/succinate and lactose+glucose, but not during growth on lactose. More recently, studies with lacGFP-transfected cells show bistability during growth on TMG/succinate, but not during growth on lactose and lactose+glucose. In the literature, these results are invariably attributed to variations in the destabilizing effect of the positive feedback generated by induction. Specifically, during growth on TMG/succinate, lac induction generates strong positive feedback because the permease stimulates the accumulation of intracellular TMG, which in turn, promotes the synthesis of even more permease. This positive feedback is attenuated during growth on lactose because hydrolysis of intracellular lactose by beta-galactosidase suppresses the stimulatory effect of the permease. It is attenuated even more during growth on lactose + glucose because glucose inhibits the uptake of lactose. But it is clear that the stabilizing effect of dilution also changes dramatically as a function of the medium composition. For instance, during growth on TMG/succinate, the dilution rate of lac permease is proportional to its activity, e, because the specific growth rate is independent of e (it is completely determined by the concentration of succinate). However, during growth on lactose, the dilution rate of the permease is proportional to e2 because the specific growth rate is proportional to the specific lactose uptake rate, which in turn, proportional to e. We show that: (a) This dependence on e2 creates such a strong stabilizing effect that bistability is virtually impossible during growth on lactose, even in the face of the intense positive feedback generated by induction. (b) This stabilizing effect is weakened during growth on lactose+glucose because the specific growth rate on glucose is independent of e, so that the dilution rate once again contains a term that is proportional to e. These results imply that the lac operon is much more prone to bistability if the medium contains carbon sources that cannot be metabolized by the lac enzymes, e.g., succinate during growth on TMG/succinate and glucose during growth on lactose+glucose. We discuss the experimental data in the light of these results.

Targeted Therapy for Melanoma

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

Quinn, Thomas; Moore, Herbert

The research project, entitled ”Targeted Therapy for Melanoma,” was focused on investigating the use of kidney protection measures to lower the non-specific kidney uptake of the radiolabeled Pb-DOTA-ReCCMSH peptide. Previous published work demonstrated that the kidney exhibited the highest non-target tissue uptake of the 212Pb/203Pb radiolabeled melanoma targeting peptide DOTA-ReCCMSH. The radiolabeled alpha-melanocyte stimulating hormone (α-MSH) peptide analog DOTA-Re(Arg 11)CCMSH, which binds the melanocortin-1 receptor over-expressed on melanoma tumor cells, has shown promise as a PRRT agent in pre-clinical studies. High tumor uptake of 212Pb labeled DOTA-Re(Arg 11)CCMSH resulted in tumor reduction or eradication in melanoma therapy studies. Of particularmore » note was the 20-50% cure rate observed when melanoma mice were treated with alpha particle emitter 212Pb. However, as with most PRRT agents, high radiation doses to the kidneys where observed. To optimize tumor treatment efficacy and reduce nephrotoxicity, the tumor to kidney uptake ratio must be improved. Strategies to reduce kidney retention of the radiolabeled peptide, while not effecting tumor uptake and retention, can be broken into several categories including modification of the targeting peptide sequence and reducing proximal tubule reabsorption.« less

Amino Acid Transporters and Release of Hydrophobic Amino Acids in the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120.

PubMed

Pernil, Rafael; Picossi, Silvia; Herrero, Antonia; Flores, Enrique; Mariscal, Vicente

2015-04-23

Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that can use inorganic compounds such as nitrate or ammonium as nitrogen sources. In the absence of combined nitrogen, it can fix N2 in differentiated cells called heterocysts. Anabaena also shows substantial activities of amino acid uptake, and three ABC-type transporters for amino acids have been previously characterized. Seven new loci encoding predicted amino acid transporters were identified in the Anabaena genomic sequence and inactivated. Two of them were involved in amino acid uptake. Locus alr2535-alr2541 encodes the elements of a hydrophobic amino acid ABC-type transporter that is mainly involved in the uptake of glycine. ORF all0342 encodes a putative transporter from the dicarboxylate/amino acid:cation symporter (DAACS) family whose inactivation resulted in an increased uptake of a broad range of amino acids. An assay to study amino acid release from Anabaena filaments to the external medium was set up. Net release of the alanine analogue α-aminoisobutyric acid (AIB) was observed when transport system N-I (a hydrophobic amino acid ABC-type transporter) was engaged in the uptake of a specific substrate. The rate of AIB release was directly proportional to the intracellular AIB concentration, suggesting leakage from the cells by diffusion.

Rice Genotype Differences in Tolerance of Zinc-Deficient Soils: Evidence for the Importance of Root-Induced Changes in the Rhizosphere

PubMed Central

Mori, Asako; Kirk, Guy J. D.; Lee, Jae-Sung; Morete, Mark J.; Nanda, Amrit K.; Johnson-Beebout, Sarah E.; Wissuwa, Matthias

2016-01-01

Zinc (Zn) deficiency is a major constraint to rice production and Zn is also often deficient in humans with rice-based diets. Efforts to breed more Zn-efficient rice are constrained by poor understanding of the mechanisms of tolerance to deficiency. Here we assess the contributions of root growth and root Zn uptake efficiency, and we seek to explain the results in terms of specific mechanisms. We made a field experiment in a highly Zn-deficient rice soil in the Philippines with deficiency-tolerant and -sensitive genotypes, and measured growth, Zn uptake and root development. We also measured the effect of planting density. Tolerant genotypes produced more crown roots per plant and had greater uptake rates per unit root surface area; the latter was at least as important as root number to overall tolerance. Tolerant and sensitive genotypes took up more Zn per plant at greater planting densities. The greater uptake per unit root surface area, and the planting density effect can only be explained by root-induced changes in the rhizosphere, either solubilizing Zn, or neutralizing a toxin that impedes Zn uptake (possibly HCO3− or Fe2+), or both. Traits for these and crown root number are potential breeding targets. PMID:26793198

Rice Genotype Differences in Tolerance of Zinc-Deficient Soils: Evidence for the Importance of Root-Induced Changes in the Rhizosphere.

PubMed

Mori, Asako; Kirk, Guy J D; Lee, Jae-Sung; Morete, Mark J; Nanda, Amrit K; Johnson-Beebout, Sarah E; Wissuwa, Matthias

2015-01-01

Zinc (Zn) deficiency is a major constraint to rice production and Zn is also often deficient in humans with rice-based diets. Efforts to breed more Zn-efficient rice are constrained by poor understanding of the mechanisms of tolerance to deficiency. Here we assess the contributions of root growth and root Zn uptake efficiency, and we seek to explain the results in terms of specific mechanisms. We made a field experiment in a highly Zn-deficient rice soil in the Philippines with deficiency-tolerant and -sensitive genotypes, and measured growth, Zn uptake and root development. We also measured the effect of planting density. Tolerant genotypes produced more crown roots per plant and had greater uptake rates per unit root surface area; the latter was at least as important as root number to overall tolerance. Tolerant and sensitive genotypes took up more Zn per plant at greater planting densities. The greater uptake per unit root surface area, and the planting density effect can only be explained by root-induced changes in the rhizosphere, either solubilizing Zn, or neutralizing a toxin that impedes Zn uptake (possibly [Formula: see text] or Fe(2+)), or both. Traits for these and crown root number are potential breeding targets.

Effect of Thiols, Zinc, and Redox Conditions on Hg Uptake in Shewanella oneidensis

DOE PAGES

Szczuka, Aleksandra; Morel, Francois M. M.; Schaefer, Jeffra K.

2015-05-18

Mercury uptake in bacteria represents a key first step in the production and accumulation Of methylmercury in biota. Previous experiments with mercury methylating bacteria have shown that Hg uptake is enhanced by some thiols, in particular cysteine, and that it is an energy-dependent process through heavy Metal TA transporters. In this study, we examine Hg uptake in the nonmethylating facultative aerobe, Shewanella oneidensis, under both anaerobic and aerobic conditions. Our results demonstrate similar characteristics of the Hg uptake system to those of the Hg methylating strains: uptake is enhanced in the presence of some thiols but not others; uptake ismore » energy dependent as evidenced by inhibition by a protonophore; and uptake is inhibited by high Zn(II) concentrations. Initial cellular uptake rates in S. oneidensis were remarkably similar under aerobic and fumarate-reducing conditions. In conclusion, these data support a similar Hg(II) uptake mechanism within the proteobacteria of accidental Hg(II) transport through heavy metal transporters with similar rates of uptake but differences in the ability to take up Hg bound to different thiols.« less

A comparison of chelator-facilitated metal uptake by a halophyte and a glycophyte.

PubMed

Jordan, Fiona L; Robin-Abbott, Molly; Maier, Raina M; Glenn, Edward P

2002-12-01

Phytoextraction is the use of plants to remove contaminants, in particular metals, from soil via root uptake and translocation to the shoots. Efficient phytoextraction requires high-biomass plants with efficient translocating properties. Halophytes characteristically accumulate large quantities of salts in above ground tissue material and can have high biomass production. It has been speculated that salt-tolerant plants may also be heavy metal tolerant and, further, may be able to accumulate metals. This study compared growth and metal uptake by a halophyte, Atriplex nummularia, and a common glycophyte, Zea mays, in a mine-tailing contaminated soil:mulch mixture. Two chelators, ethylenediaminetetraacetic acid (EDTA) and rhamnolipid, were used to facilitate plant metal uptake. Despite a lower growth rate (2% growth/d) in the contaminated soil, the halophyte accumulated roughly the same amount of metals as the glycophyte on a mass basis (30-40 mg/kg dry wt). Neither plant, however, hyperaccumulated any of the metals tested. When treated with EDTA, specific differences in patterns of metal uptake between the two plants emerged. The halophyte accumulated significantly more Cu (2x) and Pb (1x) in the shoots than the glycophyte, but root metal concentrations were generally higher for the glycophyte, indicating that the halophyte translocated more metal from the root to the shoot than the glycophyte. For example, Zn shoot-to-root ratios ranged from 1.4 to 2.1 for Atriplex and from 0.5 to 0.6 for Z. mays. The biodegradable chelator rhamnolipid was not effective at enhancing shoot metal concentrations, even though radiolabeled chelator was found in the shoot material of both plants. Our results suggest that halophytes, despite their slower growth rates, may have greater potential to selectively phytoextract metals from contaminated soils than glycophytes.

Ouabain-insensitive salt and water movements in duck red cells. I. Kinetics of cation transport under hypertonic conditions

PubMed Central

Schmidt III, WF; McManus, TJ

1977-01-01

Duck red cells in hypertonic media experience rapid osmotic shrinkage followed by gradual reswelling back toward their original volume. This uptake of salt and water is self limiting and demands a specific ionic composition of the external solution. Although ouabain (10(-4)M) alters the pattern of cation accumulation from predominantly potassium to sodium, it does not affect the rate of the reaction, or the total amount of salt or water taken up. To study the response without the complications of active Na-K transport, ouabain was added to most incubations. All water accumulated by the cells can be accounted for by net salt uptake. Specific external cation requirements for reswelling include: sufficient sodium (more than 23 mM), and elevated potassium (more than 7 mM). In the absence of external potassium cells lose potassium without gaining sodium and continue to shrink instead of reswelling. Adding rubidium to the potassium- free solution promotes an even greater loss of cell potassium, yet causes swelling due to a net uptake of sodium and rubidium followed by chloride. The diuretic furosemide (10(-3)M) inhibits net sodium uptake which depends on potassium (or rubidium), as well as inhibits net sodium uptake which depends on sodium. As a result, cell volume is stabilized in the presence of this drug by inhibition of shrinkage, at low, and of swelling at high external potassium. The response has a high apparent energy of activation (15-20 kcal/mol). We propose that net salt and water movements in hypertonic solutions containing ouabain are mediated by direct coupling or cis-interaction, between sodium and potassium so that the uphill movement of one is driven by the downhill movement of the other in the same direction. PMID:894251

The absorption of protons with specific amino acids and carbohydrates by yeast

PubMed Central

Seaston, A.; Inkson, C.; Eddy, A. A.

1973-01-01

1. Proton uptake in the presence of various amino acids was studied in washed yeast suspensions containing deoxyglucose and antimycin to inhibit energy metabolism. A series of mutant strains of Saccharomyces cerevisiae with defective amino acid permeases was used. The fast absorption of glycine, l-citrulline and l-methionine through the general amino acid permease was associated with the uptake of about 2 extra equivalents of protons per mol of amino acid absorbed, whereas the slower absorption of l-methionine, l-proline and, possibly, l-arginine through their specific permeases was associated with about 1 proton equivalent. l-Canavanine and l-lysine were also absorbed with 1–2 equivalents of protons. 2. A strain of Saccharomyces carlsbergensis behaved similarly with these amino acids. 3. Preparations of the latter yeast grown with maltose subsequently absorbed it with 2–3 equivalents of protons. The accelerated rate of proton uptake increased up to a maximum value with the maltose concentration (Km=1.6mm). The uptake of protons was also faster in the presence of α-methylglucoside and sucrose, but not in the presence of glucose, galactose or 2-deoxyglucose. All of these compounds except the last could cause acid formation. The uptake of protons induced by maltose, α-methylglucoside and sucrose was not observed when the yeast was grown with glucose, although acid was then formed both from sucrose and glucose. 4. A strain of Saccharomyces fragilis that both fermented and formed acid from lactose absorbed extra protons in the presence of lactose. 5. The observations show that protons were co-substrates in the systems transporting the amino acids and certain of the carbohydrates. PMID:4587071

Nutrient controls on new production in the Bodega Bay, California, coastal upwelling plume

NASA Astrophysics Data System (ADS)

Dugdale, R. C.; Wilkerson, F. P.; Hogue, V. E.; Marchi, A.

2006-12-01

A theoretical framework for the time-dependent processes leading to the high rates of new production in eastern boundary upwelling systems has been assembled from a series of past upwelling studies. As part of the CoOP WEST (Wind Events and Shelf Transport) study, new production in the Bodega Bay upwelling area and it's control by ambient nitrate and ammonium concentrations and the advective wind regime are described. Data and analyses are focused primarily on the WEST 2001 cruise (May-June 2001) when the two legs differed greatly in wind regimes but not nutrient concentrations. Elevated concentrations of ammonium in upwelled water with high nitrate were observed in both legs. Nitrate uptake by phytoplankton as a function of nitrate concentration was linear rather than Michaelis-Menten-like, modulated by inhibitory levels of ammonium, yielding coefficients that enable the specific nitrate uptake element of new production to be estimated from nutrient concentrations. The range of specific nitrate uptake rates for the two legs of WEST 2001 were similar, essentially a physiological response to nutrient conditions. However, the low "realization" of new production i.e. incorporation of biomass as particulate nitrogen that occurred in this system compared to the theoretical maximum possible was determined by the strong advective and turbulent conditions that dominated the second leg of the WEST 2001 study. These data are compared with other upwelling areas using a physiological shift-up model [Dugdale, R.C., Wilkerson, F.P., Morel, A. 1990. Realization of new production in coastal upwelling areas: a means to compare relative performance. Limnology and Oceanography 35, 822-829].

Predicting Phenologic Response to Water Stress and Implications for Carbon Uptake across the Southeast U.S.

NASA Astrophysics Data System (ADS)

Lowman, L.; Barros, A. P.

2016-12-01

Representation of plant photosynthesis in modeling studies requires phenologic indicators to scale carbon assimilation by plants. These indicators are typically the fraction of photosynthetically active radiation (FPAR) and leaf area index (LAI) which represent plant responses to light and water availability, as well as temperature constraints. In this study, a prognostic phenology model based on the growing season index is adapted to determine the phenologic indicators of LAI and FPAR at the sub-daily scale based on meteorological and soil conditions. Specifically, we directly model vegetation green-up and die-off responses to temperature, vapor pressure deficit, soil water potential, and incoming solar radiation. The indices are based on the properties of individual plant functional types, driven by observational data and prior modeling applications. First, we describe and test the sensitivity of the carbon uptake response to predicted phenology for different vegetation types. Second, the prognostic phenology model is incorporated into a land-surface hydrology model, the Duke Coupled Hydrology Model with Prognostic Vegetation (DCHM-PV), to demonstrate the impact of dynamic phenology on modeled carbon assimilation rates and hydrologic feedbacks. Preliminary results show reduced carbon uptake rates when incorporating a prognostic phenology model that match well against the eddy-covariance flux tower observations. Additionally, grassland vegetation shows the most variability in LAI and FPAR tied to meteorological and soil conditions. These results highlight the need to incorporate vegetation-specific responses to water limitation in order to accurately estimate the terrestrial carbon storage component of the global carbon budget.

Contrasting effects of exercise and NOS inhibition on tissue-specific fatty acid and glucose uptake in mice.

PubMed

Rottman, Jeffrey N; Bracy, Deanna; Malabanan, Carlo; Yue, Zou; Clanton, Jeff; Wasserman, David H

2002-07-01

Isotopic techniques were used to test the hypothesis that exercise and nitric oxide synthase (NOS) inhibition have distinct effects on tissue-specific fatty acid and glucose uptakes in a conscious, chronically catheterized mouse model. Uptakes were measured using the radioactive tracers (125)I-labeled beta-methyl-p-iodophenylpentadecanoic acid (BMIPP) and deoxy-[2-(3)H]glucose (DG) during treadmill exercise with and without inhibition of NOS. [(125)I]BMIPP uptake at rest differed substantially among tissues with the highest levels in heart. With exercise, [(125)I]BMIPP uptake increased in both heart and skeletal muscles. In sedentary mice, NOS inhibition induced by nitro-L-arginine methyl ester (L-NAME) feeding increased heart and soleus [(125)I]BMIPP uptake. In contrast, exercise, but not L-NAME feeding, resulted in increased heart and skeletal muscle [2-(3)H]DG uptake. Significant interactions were not observed in the effects of combined exercise and L-NAME feeding on [(125)I]BMIPP and [2-(3)H]DG uptakes. In the conscious mouse, exercise and NOS inhibition produce distinct patterns of tissue-specific fatty acid and glucose uptake; NOS is not required for important components of exercise-associated metabolic signaling, or other mechanisms compensate for the absence of this regulatory mechanism.

Effects of sewage sludge on Di-(2-ethylhexyl) phthalate uptake by plants. [Lactuca sativa L. ; Daucus carota L. ; Capsicum annuum L. ; Festuca arundinacea Schreb

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

Aranda, J.M.; O'Connor, G.A.; Eiceman, G.A.

Di-(2-ethylhexyl) phthalate (DEHP) is a priority organic pollutant frequently found in municipal sludges. A greenhouse study was conducted to determine the effect of sludge on plant uptake of {sup 14}C-DEHP (carbonyl labeled). Plants grown included three food chain crops, lettuce (Lactuca sativa L.), carrot (Daucus carota L.) and chile pepper (Capsicum annuum L.) and tall fescue (Festuca arundinacea Schreb.). Net {sup 14}C concentration in plants grown in soil amended with {sup 14}C-DEHP-contaminated sludge was independent of sludge rate (at the same DEHP loading) for lettuce, chile fruit, and carrot roots. Net {sup 14}C concentration, however, was inversely related to sludgemore » rate in carrot tops, fescue, and chile plants. Intact DEHP was not detected in plants by gas chromatography/mass spectrometry analysis. Calculated plant DEHP concentrations (based on measured net {sup 14}C concentrations and DEHP specific activities) were generally correlated better with DEHP soil solution concentrations than with total DEHP soil concentrations. Net {sup 14}C-DEHP bioconcentration factors were calculated from initial soil DEHP concentration and plant fresh weights. Bioconcentration factors ranged from 0.01 to 0.03 for fescue, lettuce, carrots, and chile, suggesting little DEHP uptake. Additionally, because intact DEHP was not detected in any plants, DEHP uptake by plants was of minor importance and would not limit sludge additions to soils used to grow these crops.« less

Pneumococcal and influenza vaccine uptake in adults with inflammatory bowel disease in France: Results from a web-based study.

PubMed

Loubet, Paul; Verger, Pierre; Abitbol, Vered; Peyrin-Biroulet, Laurent; Launay, Odile

2018-06-01

Despite specific immunization guidelines for immunocompromised patients, there is a dearth of studies on inflammatory bowel disease (IBD) population in France. To estimate the prevalence and predictors of influenza and pneumococcal vaccination rates in a sample of French IBD adults. An anonymous online survey was submitted to members of several French immunocompromised patients' associations during the winter 2016. Overall, there were 199/1625 (12%) participants with an IBD. Among these, 32% were <30 years old, 85% were male, and 62% were treated with immunosuppressive therapy. Self-reported influenza vaccine uptake was 34% (95% CI [28-41]) and 38% (95% CI [31-44]) for pneumococcal vaccines. Healthcare provider's (HCP) recommendation for vaccination (adjusted OR 12.7 95% CI [5.6-28.8]), immunosuppressive therapy (aOR 2.3 [1.1-5.3]), better knowledge of vaccination (aOR 3.2 [1.1-9.2]) and favorable attitudes towards vaccination (aOR 3.4 [1.2-9.5]) were positively associated with influenza vaccine uptake. Vaccine recommendation by HCPs was the only independently associated factor with pneumococcal vaccines uptake (OR 187.7 [24.8-1422.5]). Immunization rates in our sample do not reach recommended levels. Factors associated with vaccination included high knowledge, favorable attitudes towards vaccination and recommendation for vaccination. This underlines the role of health care providers in contact with IBD patients. Copyright © 2018 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Alkali-earth metal bridges formed in biofilm matrices regulate the uptake of fluoroquinolone antibiotics and protect against bacterial apoptosis.

PubMed

Kang, Fuxing; Wang, Qian; Shou, Weijun; Collins, Chris D; Gao, Yanzheng

2017-01-01

Bacterially extracellular biofilms play a critical role in relieving toxicity of fluoroquinolone antibiotic (FQA) pollutants, yet it is unclear whether antibiotic attack may be defused by a bacterial one-two punch strategy associated with metal-reinforced detoxification efficiency. Our findings help to assign functions to specific structural features of biofilms, as they strongly imply a molecularly regulated mechanism by which freely accessed alkali-earth metals in natural waters affect the cellular uptake of FQAs at the water-biofilm interface. Specifically, formation of alkali-earth-metal (Ca 2+ or Mg 2+ ) bridge between modeling ciprofloxacin and biofilms of Escherichia coli regulates the trans-biofilm transport rate of FQAs towards cells (135-nm-thick biofilm). As the addition of Ca 2+ and Mg 2+ (0-3.5 mmol/L, CIP: 1.25 μmol/L), the transport rates were reduced to 52.4% and 63.0%, respectively. Computational chemistry analysis further demonstrated a deprotonated carboxyl in the tryptophan residues of biofilms acted as a major bridge site, of which one side is a metal and the other is a metal girder jointly connected to the carboxyl and carbonyl of a FQA. The bacterial growth rate depends on the bridging energy at anchoring site, which underlines the environmental importance of metal bridge formed in biofilm matrices in bacterially antibiotic resistance. Copyright © 2016 Elsevier Ltd. All rights reserved.

Insights into the Adsorption of Carbon Dioxide in the Presence of Water Vapor Utilizing a Low Molecular Weight Polyethylenimine-Impregnated CARiACT Silica Sorbent

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

Monazam, Esmail R.; Breault, Ronald W.; Fauth, Daniel J.

Thermogravimetric analysis was employed to investigate the CO 2 and H 2O adsorption rates and water vapor equilibrium on anhydrous and pre-hydrate linear polyethylenimine (LPEI) sorbent impregnated within a commercially functional CARiACT G10 (HPV) silica support. Water vapor experiments utilizing specific humidity of 2%, 8%, and 16% in contact with an anhydrous PEI sorbent resulted in proportional quantities of water vapor uptake. Subsequently, both anhydrous and pre-hydrated PEI-impregnated sorbents were made available to identical humidified gaseous streams containing a CO 2 concentration of 10% at 60oC. CO 2 capacity increased dramatically in the presence of different levels of humidity. Variousmore » kinetic models were systematically employed to interpret the experimental data including single and multiple-step models. The rate data was best represented by a reaction mechanism pathway involving the interplay of CO 2 with PEI-impregnated sorbents exhibited a quick adsorption phase followed by a slow approach to equilibrium. Moreover, a phenomenological rate model was developed to describe the dynamic H 2O and CO 2 uptakes at specific humidity levels studied. The kinetic study showed good agreement with experimental data. Furthermore, the effects observed during the adsorption and hydration are shown to be complementary to known chemical and physical transformations within the polyethylenimine’s macromolecule.« less

Insights into the Adsorption of Carbon Dioxide in the Presence of Water Vapor Utilizing a Low Molecular Weight Polyethylenimine-Impregnated CARiACT Silica Sorbent

DOE PAGES

Monazam, Esmail R.; Breault, Ronald W.; Fauth, Daniel J.; ...

2017-07-20

Thermogravimetric analysis was employed to investigate the CO 2 and H 2O adsorption rates and water vapor equilibrium on anhydrous and pre-hydrate linear polyethylenimine (LPEI) sorbent impregnated within a commercially functional CARiACT G10 (HPV) silica support. Water vapor experiments utilizing specific humidity of 2%, 8%, and 16% in contact with an anhydrous PEI sorbent resulted in proportional quantities of water vapor uptake. Subsequently, both anhydrous and pre-hydrated PEI-impregnated sorbents were made available to identical humidified gaseous streams containing a CO 2 concentration of 10% at 60oC. CO 2 capacity increased dramatically in the presence of different levels of humidity. Variousmore » kinetic models were systematically employed to interpret the experimental data including single and multiple-step models. The rate data was best represented by a reaction mechanism pathway involving the interplay of CO 2 with PEI-impregnated sorbents exhibited a quick adsorption phase followed by a slow approach to equilibrium. Moreover, a phenomenological rate model was developed to describe the dynamic H 2O and CO 2 uptakes at specific humidity levels studied. The kinetic study showed good agreement with experimental data. Furthermore, the effects observed during the adsorption and hydration are shown to be complementary to known chemical and physical transformations within the polyethylenimine’s macromolecule.« less

A (99m) Tc-tricine-HYNIC-labeled peptide targeting the neurotensin receptor for single-photon imaging in malignant tumors.

PubMed

Erfani, Mostafa; Zarrabi Ahrabi, Nakisa; Shafiei, Mohammad; Shirmardi, Seyed Pezhman

2014-03-01

In this study, a new neurotensin (NT) analog was labeled with (99m) Tc via HYNIC chelator and tricine as coligand and investigated further. An NT (7-13) analog was prepared, and labeling with (99m) Tc was performed. The internalization rate and biodistribution of radiopeptide were studied in HT-29 cells and nude mice bearing tumor, respectively. Radiolabeling with (99m) Tc was performed at high specific activities (54 MBq/nmol) with an acceptable labeling yield (>95%). In vitro cell line studies showed a specific internalization uptake up to 13.23 ± 0.45% during 4 h which was blocked in the presence of excess cold peptide to 0.83 ± 0.15%. In biodistribution studies, uptake was observed in NT receptor-positive organs so that after 1 h the uptakes in mouse intestine and tumor were 1.23 ± 0.16% ID/g and 1.12 ± 0.11% ID/g, respectively. In animals co-injected with excess cold peptide, reduction uptake in tumor and intestines were 73% (1.10% vs. 0.29% ID/g at 4 h) and 61% (1.22% vs. 0.47% ID/g at 4 h) respectively. Predominant renal excretion pathway with a highest accumulation of activity in bladder was observed for this radiopeptide. This radiolabeled peptide could be a candidate for detection of NT positive tumors. Copyright © 2014 John Wiley & Sons, Ltd.

Subtle Differences in Symbiont Cell Surface Glycan Profiles Do Not Explain Species-Specific Colonization Rates in a Model Cnidarian-Algal Symbiosis

PubMed Central

Parkinson, John E.; Tivey, Trevor R.; Mandelare, Paige E.; Adpressa, Donovon A.; Loesgen, Sandra; Weis, Virginia M.

2018-01-01

Mutualisms between cnidarian hosts and dinoflagellate endosymbionts are foundational to coral reef ecosystems. These symbioses are often re-established every generation with high specificity, but gaps remain in our understanding of the cellular mechanisms that control symbiont recognition and uptake dynamics. Here, we tested whether differences in glycan profiles among different symbiont species account for the different rates at which they initially colonize aposymbiotic polyps of the model sea anemone Aiptasia (Exaiptasia pallida). First, we used a lectin array to characterize the glycan profiles of colonizing Symbiodinium minutum (ITS2 type B1) and noncolonizing Symbiodinium pilosum (ITS2 type A2), finding subtle differences in the binding of lectins Euonymus europaeus lectin (EEL) and Urtica dioica agglutinin lectin (UDA) that distinguish between high-mannoside and hybrid-type protein linked glycans. Next, we enzymatically cleaved glycans from the surfaces of S. minutum cultures and followed their recovery using flow cytometry, establishing a 48–72 h glycan turnover rate for this species. Finally, we exposed aposymbiotic host polyps to cultured S. minutum cells masked by EEL or UDA lectins for 48 h, then measured cell densities the following day. We found no effect of glycan masking on symbiont density, providing further support to the hypothesis that glycan-lectin interactions are more important for post-phagocytic persistence of specific symbionts than they are for initial uptake. We also identified several methodological and biological factors that may limit the utility of studying glycan masking in the Aiptasia system. PMID:29765363

Explaining variation in Down's syndrome screening uptake: comparing the Netherlands with England and Denmark using documentary analysis and expert stakeholder interviews.

PubMed

Crombag, Neeltje M T H; Vellinga, Ynke E; Kluijfhout, Sandra A; Bryant, Louise D; Ward, Pat A; Iedema-Kuiper, Rita; Schielen, Peter C J I; Bensing, Jozien M; Visser, Gerard H A; Tabor, Ann; Hirst, Janet

2014-09-25

The offer of prenatal Down's syndrome screening is part of routine antenatal care in most of Europe; however screening uptake varies significantly across countries. Although a decision to accept or reject screening is a personal choice, it is unlikely that the widely differing uptake rates across countries can be explained by variation in individual values alone.The aim of this study was to compare Down's syndrome screening policies and programmes in the Netherlands, where uptake is relatively low (<30%) with England and Denmark where uptake is higher (74 and > 90% respectively), in an attempt to explain the observed variation in national uptake rates. We used a mixed methods approach with an embedded design: a) documentary analysis and b) expert stakeholder analysis. National central statistical offices and legal documents were studied first to gain insight in demographic characteristics, cultural background, organization and structure of healthcare followed by documentary analysis of primary and secondary sources on relevant documents on DSS policies and programme. To enhance interpretation of these findings we performed in-depth interviews with relevant expert stakeholders. There were many similarities in the demographics, healthcare systems, government abortion legislation and Down's syndrome screening policy across the studied countries. However, the additional cost for Down's syndrome screening over and above standard antenatal care in the Netherlands and an emphasis on the 'right not to know' about screening in this country were identified as potential explanations for the 'low' uptake rates of Down's syndrome screening in the Netherlands. The social context and positive framing of the offer at the service delivery level may play a role in the relatively high uptake rates in Denmark. This paper makes an important contribution to understanding how macro-level demographic, social and healthcare delivery factors may have an impact on national uptake rates for Down's syndrome screening. It has suggested a number of policy level and system characteristics that may go some way to explaining the relatively low uptake rates of Down's syndrome screening in the Netherlands when compared to England and Denmark.

Bicarbonate uptake via an anion exchange protein is the main mechanism of inorganic carbon acquisition by the giant kelp Macrocystis pyrifera (Laminariales, Phaeophyceae) under variable pH.

PubMed

Fernández, Pamela A; Hurd, Catriona L; Roleda, Michael Y

2014-12-01

Macrocystis pyrifera is a widely distributed, highly productive, seaweed. It is known to use bicarbonate (HCO3 (-) ) from seawater in photosynthesis and the main mechanism of utilization is attributed to the external catalyzed dehydration of HCO3 (-) by the surface-bound enzyme carbonic anhydrase (CAext ). Here, we examined other putative HCO3 (-) uptake mechanisms in M. pyrifera under pHT 9.00 (HCO3 (-) : CO2  = 940:1) and pHT 7.65 (HCO3 (-) : CO2  = 51:1). Rates of photosynthesis, and internal CA (CAint ) and CAext activity were measured following the application of AZ which inhibits CAext , and DIDS which inhibits a different HCO3 (-) uptake system, via an anion exchange (AE) protein. We found that the main mechanism of HCO3 (-) uptake by M. pyrifera is via an AE protein, regardless of the HCO3 (-) : CO2 ratio, with CAext making little contribution. Inhibiting the AE protein led to a 55%-65% decrease in photosynthetic rates. Inhibiting both the AE protein and CAext at pHT 9.00 led to 80%-100% inhibition of photosynthesis, whereas at pHT 7.65, passive CO2 diffusion supported 33% of photosynthesis. CAint was active at pHT 7.65 and 9.00, and activity was always higher than CAext , because of its role in dehydrating HCO3 (-) to supply CO2 to RuBisCO. Interestingly, the main mechanism of HCO3 (-) uptake in M. pyrifera was different than that in other Laminariales studied (CAext -catalyzed reaction) and we suggest that species-specific knowledge of carbon uptake mechanisms is required in order to elucidate how seaweeds might respond to future changes in HCO3 (-) :CO2 due to ocean acidification. © 2014 Phycological Society of America.

Molecular analysis of maltotriose transport and utilization by Saccharomyces cerevisiae.

PubMed

Day, Rachel E; Rogers, Peter J; Dawes, Ian W; Higgins, Vincent J

2002-11-01

Efficient fermentation of maltotriose is a desired property of Saccharomyces cerevisiae for brewing. In a standard wort, maltotriose is the second most abundant sugar, and slower uptake leads to residual maltotriose in the finished product. The limiting factor of sugar metabolism is its transport, and there are conflicting reports on whether a specific maltotriose permease exists or whether the mechanisms responsible for maltose uptake also carry out maltotriose transport. In this study, radiolabeled maltotriose was used to show that overexpression of the maltose permease gene, MAL61, in an industrial yeast strain resulted in an increase in the rate of transport of maltotriose as well as maltose. A strain derived from W303-1A and lacking any maltose or maltotriose transporter but carrying a functional maltose transport activator (MAL63) was developed. By complementing this strain with permeases encoded by MAL31, MAL61, and AGT1, it was possible to measure their specific transport kinetics by using maltotriose and maltose. All three permeases were capable of high-affinity transport of maltotriose and of allowing growth of the strain on the sugar. Maltotriose utilization from the permease encoded by AGT1 was regulated by the same genetic mechanisms as those involving the maltose transcriptional activator. Competition studies carried out with two industrial strains, one not containing any homologue of AGT1, showed that maltose uptake and maltotriose uptake were competitive and that maltose was the preferred substrate. These results indicate that the presence of residual maltotriose in beer is not due to a genetic or physiological inability of yeast cells to utilize the sugar but rather to the lower affinity for maltotriose uptake in conjunction with deteriorating conditions present at the later stages of fermentation. Here we identify molecular mechanisms regulating the uptake of maltotriose and determine the role of each of the transporter genes in the cells.

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.

Application of balancing methods in modeling the penicillin fermentation.

PubMed

Heijnen, J J; Roels, J A; Stouthamer, A H

1979-12-01

This paper shows the application of elementary balancing methods in combination with simple kinetic equations in the formulation of an unstructured model for the fed-batch process for the production of penicillin. The rate of substrate uptake is modeled with a Monod-type relationship. The specific penicillin production rate is assumed to be a function of growth rate. Hydrolysis of penicillin to penicilloic acid is assumed to be first order in penicillin. In simulations with the present model it is shown that the model, although assuming a strict relationship between specific growth rate and penicillin productivity, allows for the commonly observed lag phase in the penicillin concentration curve and the apparent separation between growth and production phase (idiophase-trophophase concept). Furthermore it is shown that the feed rate profile during fermentation is of vital importance in the realization of a high production rate throughout the duration of the fermentation. It is emphasized that the method of modeling presented may also prove rewarding for an analysis of fermentation processes other than the penicillin fermentation.

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.

Quantitative analysis of [99mTc]C2A-GST distribution in the area at risk after myocardial ischemia and reperfusion using a compartmental model.

PubMed

Audi, Said; Poellmann, Michael; Zhu, Xiaoguang; Li, Zhixin; Zhao, Ming

2007-11-01

It was recently demonstrated that the radiolabeled C2A domain of synaptotagmin I accumulates avidly in the area at risk after ischemia and reperfusion. The objective was to quantitatively characterize the dynamic uptake of radiolabeled C2A in normal and ischemically injured myocardia using a compartmental model. To induce acute myocardial infarction, the left descending coronary artery was ligated for 18 min, followed by reperfusion. [99mTc]C2A-GST or its inactivated form, [99mTc]C2A-GST-NHS, was injected intravenously at 2 h after reperfusion. A group of four rats was sacrificed at 10, 30, 60 and 180 after injection. Uptake of [99mTc]C2A-GST and [99mTc]C2A-GST-NHS in the area at risk and in the normal myocardium were determined by gamma counting. A compartmental model was developed to quantitatively interpret myocardial uptake kinetic data. The model consists of two physical spaces (vascular space and tissue space), with plasma activity as input. The model allows for [99mTc]C2A-GST and [99mTc]C2A-GST-NHS diffusion between vascular and tissue spaces, as well as for [99mTc]C2A-GST sequestration in vascular and tissue spaces via specific binding. [99mTc]C2A-GST uptake in the area at risk was significantly higher than that for [99mTc]C2A-GST-NHS at all time points. The compartmental model separated [99mTc]C2A-GST uptake in the area at risk due to passive retention from that due to specific binding. The maximum amount of [99mTc]C2A-GST that could be sequestered in the area at risk due to specific binding was estimated at a total of 0.048 nmol/g tissue. The rate of [99mTc]C2A-GST sequestration within the tissue space of the area at risk was 0.012 ml/min. Modeling results also revealed that the diffusion rate of radiotracer between vascular and tissue spaces is the limiting factor of [99mTc]C2A-GST sequestration within the tissue space of the area at risk. [99mTc]C2A-GST is sequestered in the ischemically injured myocardium in a well-defined dynamic profile. Model parameters will be valuable indicators for gauging and guiding the development of future-generation molecular probes.

The logistic growth of duckweed (Lemna minor) and kinetics of ammonium uptake.

PubMed

Zhang, Kun; Chen, You-Peng; Zhang, Ting-Ting; Zhao, Yun; Shen, Yu; Huang, Lei; Gao, Xu; Guo, Jin-Song

2014-01-01

Mathematical models have been developed to describe nitrogen uptake and duckweed growth experimentally to study the kinetics of ammonium uptake under various concentrations. The kinetics of duckweed ammonium uptake was investigated using the modified depletion method after plants were grown for two weeks at different ammonium concentrations (0.5-14 mg/L) in the culture medium. The maximum uptake rate and Michaelis-Menten constant for ammonium were estimated as 0.082 mg/(g fresh weight x h) and 1.877 mg/L, respectively. Duckweed growth was assessed when supplied at different total nitrogen (TN) concentrations (1-5 mg/L) in the culture medium. The results showed that the intrinsic growth rate was from 0.22 to 0.26 d(-1), and TN concentrations had no significant influence on the duckweed growth rate.

Cyclic variations in nitrogen uptake rate of soybean plants: effects of external nitrate concentration

NASA Technical Reports Server (NTRS)

Tolley-Henry, L.; Raper, C. D. Jr; Granato, T. C.; Raper CD, J. r. (Principal Investigator)

1988-01-01

Net uptake of NO3- by non-nodulated soybean plants [Glycine max (L.) Merr. cv. Ransom] growing in flowing hydroponic cultures containing 0.5, 1.0 and 10.0 mol m-3 NO3- was measured daily during a 24-d period of vegetative development to determine if amplitude of maximum and minimum rates of net NO3- uptake are responsive to external concentrations of NO3-. Removal of NO3- from the replenished solutions during each 24-h period was determined by ion chromatography. Neither dry matter accumulation nor the periodicity of oscillations in net uptake rate was altered by the external NO3- concentrations. The maxima of the oscillations in net uptake rate, however, increased nearly 3-fold in response to external NO3- concentrations. The maxima and minima, respectively, changed from 4.0 and 0.6 mmol NO3- per gram root dry weight per day at an external solution level of 0.5 mol m-3 NO3- to 15.2 and -2.7 mmol NO3- per gram root dry weight per day at an external solution level of 10.0 mol m-3 NO3-. The negative values for minimum net uptake rate from 10.0 mol m-3 NO3- solutions show that net efflux was occurring and indicate that the magnitude of the efflux component of net uptake was responsive to external concentration of NO3-.

Cyclic variations in nitrogen uptake rate in soybean plants: uptake during reproductive growth

NASA Technical Reports Server (NTRS)

Vessey, J. K.; Raper, C. D. Jr; Henry, L. T.; Raper CD, J. r. (Principal Investigator)

1990-01-01

Net uptake of NO3- by non-nodulated soybean plants [Glycine max (L.) Merr. cv. Ransom] growing in flowing hydroponic culture was measured daily during a 63 d period of reproductive development between the first florally inductive photoperiod and [unknown word] seed growth. Removal of NO3- from a replenished solution containing 1.0 mol m-3 NO3- was determined by ion chromatography. Uptake of NO3- continued throughout reproductive development. The net uptake rate of NO3- cycled between maxima and minima with a periodicity of oscillation of 3 to 7 d during the floral stage and about 6 d during the fruiting stage. Coupled with increasing concentrations of carbon and C : N ratios in tissues, the oscillations in net uptake rates of NO3- are evidence that the demand for carbohydrate by reproductive organs is contingent on the availability of nitrogen in the shoot pool rather than that the demand for nitrogen follows the flux of carbohydrate into reproductive tissues.

Regional impacts of climate change on a temperate mixed forest: species-specific microscopic root water uptake strategies

NASA Astrophysics Data System (ADS)

He, L.; Ivanov, V. Y.; Bisht, G.; Schneider, C.; Kalbacher, T.; Hildebrandt, A.

2013-12-01

The current generation of ecohydrological or land surface models oversimplify fine-scale root water uptake processes and are thus likely to produce errors in estimating regional transpiration flux when soil approaches dry condition. As future climate is likely to result in a drier soil state in many regions around the world, a better understanding and numerical representation of plant root water uptake process is crucial. In this study, a microscopic root water uptake approach is proposed to simulate the three-dimensional radial moisture fluxes from the soil to roots, and water flux transfer processes within the root systems. During dry conditions, this microscopic approach can simulate plant's ability to compensate the suppressed root water uptake in water-stressed regions by increasing uptake density in moister regions. This study incorporated the microscopic root water uptake approach based on 'aRoot' and 'PFLOTRAN' models into a larger-scale ecohydrological model ('tRIBS+VEGGIE'). The ecohydrological model provides boundary conditions for the microscopic module, and the latter feedbacks with actual transpiration rates and profiles of moisture sinks. The study is conducted for a northern temperate mixed forest of Northern Michigan. The study addresses two species (oak and aspen) with different root architectures, the primary and secondary type root systems. The modeling results use historical climate situations, as well as empirical observations suggesting that transpiration was not limited by soil moisture even when the surface soil water content approached the residual value. Climate projection scenarios are used to predict different water stress levels that would be experienced by the studied species.

Awareness and uptake of colorectal, breast, cervical and prostate cancer screening tests in Spain.

PubMed

Carrasco-Garrido, Pilar; Hernandez-Barrera, Valentın; Lopez de Andres, Ana; Jimenez-Trujillo, Isabel; Gallardo Pino, Carmen; Jimenez-Garcıa, Rodrigo

2014-04-01

We aim to describe levels of awareness and uptake of colorectal, breast, cervical and prostate cancer screening tests and to analyze the association to socio-demographic and health-related variables. Population-based cross-sectional study conducted using a home-based personal interview survey on a nationwide representative sample (n = 7938) of population aged ≥18 years (Oncobarometro Survey). Awareness was assessed by asking participants: Now I am going to mention several medical tests for cancer detection, please tell me if you already know about them or if this is the first time you have heard of them? The tests mentioned were faecal occult blood test (FOBT), mammography, Pap smear and prostate-specific antigen (PSA). Cancer screening uptake was assessed by asking participants whether they had received tests within the previous 2 years. Awareness rates of 38.55% for FOBT, 95.03% for mammography, 70.84% for Pap smears and 54.72% for PSA were found. Uptake mammography was 74.46%, Pap smears 65.57%, PSA 35.19% and FOBT 9.40%. Factors such as immigration status, lower educational level or income and not suffering from chronic conditions are negative predictors for uptake. Awareness and uptake results showed acceptable figures for mammography, moderate for Pap smears and unacceptably low for FOBT. Inequalities exist in uptake of cancer screening. It is necessary to develop public health educational programmes, especially for the vulnerable populations, aiming to inform and motivate them to use screening services on a regular basis. Our data suggest that although PSA is not recommended, this opportunistic screening is frequently used in Spain.

Hierarchically porous organic polymers: highly enhanced gas uptake and transport through templated synthesis.

PubMed

Chakraborty, Sanjiban; Colón, Yamil J; Snurr, Randall Q; Nguyen, SonBinh T

2015-01-01

Porous organic polymers (POPs) possessing meso- and micropores can be obtained by carrying out the polymerization inside a mesoporous silica aerogel template and then removing the template after polymerization. The total pore volume (tpv) and specific surface area (ssa) can be greatly enhanced by modifying the template (up to 210% increase for tpv and 73% for ssa) as well as by supercritical processing of the POPs (up to an additional 142% increase for tpv and an additional 32% for ssa) to include larger mesopores. The broad range of pores allows for faster transport of molecules through the hierarchically porous POPs, resulting in increased diffusion rates and faster gas uptake compared to POPs with only micropores.

Predicting dietborne metal toxicity from metal influxes

USGS Publications Warehouse

Croteau, M.-N.; Luoma, S.N.

2009-01-01

Dietborne metal uptake prevails for many species in nature. However, the links between dietary metal exposure and toxicity are not well understood. Sources of uncertainty include the lack of suitable tracers to quantify exposure for metals such as copper, the difficulty to assess dietary processes such as food ingestion rate, and the complexity to link metal bioaccumulation and effects. We characterized dietborne copper, nickel, and cadmium influxes in a freshwater gastropod exposed to diatoms labeled with enriched stable metal isotopes. Metal influxes in Lymnaea stagnalis correlated linearly with dietborne metal concentrations over a range encompassing most environmental exposures. Dietary Cd and Ni uptake rate constants (kuf) were, respectively, 3.3 and 2.3 times higher than that for Cu. Detoxification rate constants (k detox) were similar among metals and appeared 100 times higher than efflux rate constants (ke). Extremely high Cu concentrations reduced feeding rates, causing the relationship between exposure and influx to deviate from linearity; i.e., Cu uptake rates leveled off between 1500 and 1800 nmol g-1 day-1. L. stagnalis rapidly takes up Cu, Cd, and Ni from food but detoxifies the accumulated metals, instead of reducing uptake or intensifying excretion. Above a threshold uptake rate, however, the detoxification capabilities of L. stagnalis are overwhelmed.

A Radiochemical Biotechnological Approach: Preliminary Study of Lactose Uptake Rate by Kefir Cells, Using 14C-labeled Lactose, in Anaerobic Fermentation

NASA Astrophysics Data System (ADS)

Golfinopoulos, A.; Soupioni, M.; Kanellaki, M.; Koutinas, A. A.

2008-08-01

The effect of initial lactose concentration on lactose uptake rate by kefir free cells, during the lactose fermentation, was studied in this work. For the investigation 14C-labelled lactose was used due to the fact that labeled and unlabeled molecules are fermented in the same way. The results illustrated lactose uptake rates are about up to two fold higher at lower initial ∘Bé densities as compared with higher initial ∘Bé densities.

Gaseous oxygen uptake in porous media at different moisture contents and airflow velocities.

PubMed

Sharma, Prabhakar; Poulsen, Tjalfe G; Kalluri, Prasad N V

2009-06-01

The presence and distribution of water in the pore space is a critical factor for flow and transport of gases through unsaturated porous media. The water content also affects the biological activity necessary for treatment of polluted gas streams in biofilters. In this research, microbial activity and quantity of inactive volume in a porous medium as a function of moisture content and gas flow rate were investigated. Yard waste compost was used as a test medium, and oxygen uptake rate measurements were used to quantify microbial activity and effective active compost volume using batch and column flow-through systems. Compost water contents were varied from air-dry to field capacity and gas flows ranged from 0.2 to 2 L x min(-1). The results showed that overall microbial activity and the relative fraction of active compost medium volume increased with airflow velocity for all levels of water content up to a certain flow rate above which the oxygen uptake rate assumed a constant value independent of gas flow. The actual value of the maximum oxygen uptake rate was controlled by the water content. The oxygen uptake rate also increased with increasing water content and reached a maximum between 42 and 48% volumetric water content, above which it decreased, again likely because of formation of inactive zones in the compost medium. Overall, maximum possible oxygen uptake rate as a function of gas flow rate across all water contents and gas flows could be approximated by a linear expression. The relative fraction of active volume also increased with gas flow rate and reached approximately 80% for the highest gas flows used.

Uptake of Free HPV Vaccination among Young Women: A Comparison of Rural versus Urban Rates

ERIC Educational Resources Information Center

Crosby, Richard A.; Casey, Baretta R.; Vanderpool, Robin; Collins, Tom; Moore, Gregory R.

2011-01-01

Purpose: To contrast rates of initial HPV vaccine uptake, offered at no cost, between a rural clinic, a rural community college, and an urban college clinic and to identify rural versus urban differences in uptake of free booster doses. Methods: Young rural women attending rural clinics (n = 246), young women attending a rural community college (n…

Liquid scintillation counting for /sup 14/C uptake of single algal cells isolated from natural samples

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

Rivkin, R.B.; Seliger, H.H.

1981-07-01

Short term rates of /sup 14/C uptake for single cells and small numbers of isolated algal cells of five phytoplankton species from natural populations were measured by liquid scintillation counting. Regression analysis of uptake rates per cell for cells isolated from unialgal cultures of seven species of dinoflagellates, ranging in volume from ca. 10/sup 3/ to 10/sup 7/ ..mu..m/sup 3/, gave results identical to uptake rates per cell measured by conventional /sup 14/C techniques. Relative standard errors or regression coefficients ranged between 3 and 10%, indicating that for any species there was little variation in photosynthesis per cell.

[Kinetic properties of the fructose influx across the brush border of the rat jejunum. Effects of a diet rich in fructose].

PubMed

Crouzoulon, G

1978-10-01

The unidirectional influx (i.e. initial rate of uptake) of D-fructose across the brush border of rat jejunum is a saturable function of concentration, with a Kt of 125 mM, which implicates a carrier mechanism. This mechanism appears to be very specific for fructose in view of the lack of influx inhibition observed in the presence of large concentrations of the sugars or polyols, D-glucose, D-galactose, D-mannose, D-xylose, L-sorbose, D-tagatose, sorbitol or mannitol. D-Fructose uptake is inhibited by incubation, preceded by a 30-min preincubation in the same inhibitory conditions, in the absence of Na, or in the presence of metabolic poisons, NaF, 2,4-dinitrophenol, monoiodoacetate. Phloridzin (10-3 M), with or without preincubation, has no effect on uptake. D-Fructose influx is stimulated by fructose feeding, mainly because the augmentation of the number of active sites of transfer: Jmax is increased two-fold, Kt is more weakly affected.

Use of pregnancy counselling services in Australia 2007-2012.

PubMed

Shelley, Julia M; Kavanagh, Shane; Graham, Melissa; Mayes, Catherine

2015-02-01

To assess the uptake of Medicare Benefit payments for non-directive pregnancy support counselling which commenced in November 2006. Counts of services for pregnancy counselling from 1 July 2007 to 30 June 2012, where a Medicare rebate was paid, were used to calculate age-, state- and provider-specific rates per 100,000 women aged 15-44 years, and rates per 100,000 births for each study year. Rates of Medicare rebates for pregnancy counselling were low, with a mean of 90.6 services per 100,000 women recorded over the study period. GP services were accessed most frequently, while services provided by allied health professionals averaged less than 5% of those for GPs. The overall rate of services fell in all jurisdictions except Victoria/Tasmania, although services provided by allied health professionals remained steady or rose in all jurisdictions over the study period. There has been a low uptake of pregnancy counselling covered by the Medicare Benefits Item numbers introduced in 2006, especially for services provided by allied health professionals. Due to a lack of available data, the impact on abortion rates is unknown. Provision of Medicare rebates for pregnancy counselling does not appear to be an effective way of assisting women with unintended pregnancies. © 2015 Public Health Association of Australia.

Nitrate Transport Is Independent of NADH and NAD(P)H Nitrate Reductases in Barley Seedlings 1

PubMed Central

Warner, Robert L.; Huffaker, Ray C.

1989-01-01

Barley (Hordeum vulgare L.) has NADH-specific and NAD(P)H-bispecific nitrate reductase isozymes. Four isogenic lines with different nitrate reductase isozyme combinations were used to determine the role of NADH and NAD(P)H nitrate reductases on nitrate transport and assimilation in barley seedlings. Both nitrate reductase isozymes were induced by nitrate and were required for maximum nitrate assimilation in barley seedlings. Genotypes lacking the NADH isozyme (Az12) or the NAD(P)H isozyme (Az70) assimilated 65 or 85%, respectively, as much nitrate as the wild type. Nitrate assimilation by genotype (Az12;Az70) which is deficient in both nitrate reductases, was only 13% of the wild type indicating that the NADH and NAD(P)H nitrate reductase isozymes are responsible for most of the nitrate reduction in barley seedlings. For all genotypes, nitrate assimilation rates in the dark were about 55% of the rates in light. Hypotheses that nitrate reductase has direct or indirect roles in nitrate uptake were not supported by this study. Induction of nitrate transporters and the kinetics of net nitrate uptake were the same for all four genotypes indicating that neither nitrate reductase isozyme has a direct role in nitrate uptake in barley seedlings. PMID:11537465

Uptake and selective partitioning of dietary lipids to ovarian and muscle tissue of maturing female coho salmon, Oncorhynchus kisutch, during secondary oocyte growth.

PubMed

Johnson, Ronald B; Kroeger, Eric L; Reichert, William L; Carter, Cameron S; Rust, Michael B

2017-06-01

Female coho salmon, Oncorhynchus kisutch, were fed one of two experimental feeds containing lipids with markedly different stable 13 C isotope signatures during the late cortical alveolus, lipid droplet, and vitellogenesis stages of secondary oocyte growth. Ovarian and muscle lipids fatty acid concentrations were significantly affected by treatment during all three stages of development. Stable 13 C isotope analyses confirmed that dietary lipids were incorporated into both ovarian and muscle lipids during all three stages and revealed that ovarian lipids were more affected than muscle lipids during vitellogenesis. Arachidonic acid (ARA) was incorporated into ovarian lipids at the highest rate of all fatty acids examined with the greatest uptake observed during the cortical alveolus and lipid droplet stages of development. Docosahexaenoic acid (DHA) was incorporated into ovarian lipids at the next highest rate with the greatest uptake observed during the lipid droplet stage of development. The presence of an ovary specific, fatty acid transfer mechanism is proposed. Results from this study demonstrate the ability to greatly alter the fatty acid composition of ovarian lipids through a dietary change during secondary oocyte growth and may be of great interest to producers of farmed salmon and salmon broodstock programs. Published by Elsevier Inc.

Designing herbicide formulation characteristics to maximize efficacy and minimize rice injury in paddy environments.

PubMed

Cryer, S A; Mann, R K; Erhardt-Zabik, S; Keeney, F N; Handy, P R

2001-06-01

Mathematical descriptors, coupled with experimental observations, are used to quantify differential uptake of an experimental herbicide in Japonica and Indica rice (Oryza sativa, non-target) and barnyardgrass (Echinochloa crus-galli, target). Partitioning, degradation, plant uptake and metabolism are described using mass-balance conservation equations in the form of kinetic approximations. Estimated environmental concentrations, governed by the pesticide formulation, are described using superimposed analytical solutions for the one-dimensional diffusion equation in spherical coordinates and by a finite difference representation of the two-dimensional diffusion equation in Cartesian coordinates. Formulation attributes from granules include active ingredient release rates, particle sizes, pesticide loading, and granule spacing. The diffusion model for pesticide transport is coupled with the compartment model to follow the fate and transport of a pesticide from its initial application location to various environmental matrices of interest. Formulation effects, partitioning and degradation in the various environmental matrices, differential plant uptake and metabolism, and dose-response information for plants are accounted for. This novel model provides a mechanism for selecting formulation delivery systems that optimize specific attributes (such as weed control or the therapeutic index) for risk-assessment procedures. In this report we describe how this methodology was used to explore the factors affecting herbicide efficacy and to define an optimal release rate for a granule formulation.

Effect of Pore Clogging on Kinetics of Lead Uptake by Clinoptilolite.

PubMed

Inglezakis; Diamandis; Loizidou; Grigoropoulou

1999-07-01

The kinetics of lead-sodium ion exchange using pretreated natural clinoptilolite are investigated, more specifically the influence of agitation (0, 210, and 650 rpm) on the limiting step of the overall process, for particle sizes of 0.63-0.8 and 0.8-1 mm at ambient temperature and initial lead solutions of 500 mg l-1 without pH adjustment. The isotopic exchange model is found to fit the ion exchange process. Particle diffusion is shown to be the controlling step for both particle sizes under agitation, while in the absence of agitation film diffusion is shown to control. The ion exchange process effective diffusion coefficients are calculated and found to depend strongly on particle size in the case of agitation at 210 rpm and only slightly on particle size at 650 rpm. Lead uptake rates are higher for smaller particles only at rigorous agitation, while at mild agitation the results are reversed. These facts are due to partial clogging of the pores of the mineral during the grinding process. This is verified through comparison of lead uptake rates for two samples of the same particle size, one of which is rigorously washed for a certain time before being exposed to the ion exchange. Copyright 1999 Academic Press.

Nitrate transport is independent of NADH and NAD(P)H nitrate reductases in barley seedlings

NASA Technical Reports Server (NTRS)

Warner, R. L.; Huffaker, R. C.

1989-01-01

Barley (Hordeum vulgare L.) has NADH-specific and NAD(P)H-bispecific nitrate reductase isozymes. Four isogenic lines with different nitrate reductase isozyme combinations were used to determine the role of NADH and NAD(P)H nitrate reductases on nitrate transport and assimilation in barley seedlings. Both nitrate reductase isozymes were induced by nitrate and were required for maximum nitrate assimilation in barley seedlings. Genotypes lacking the NADH isozyme (Az12) or the NAD(P)H isozyme (Az70) assimilated 65 or 85%, respectively, as much nitrate as the wild type. Nitrate assimilation by genotype (Az12;Az70) which is deficient in both nitrate reductases, was only 13% of the wild type indicating that the NADH and NAD(P)H nitrate reductase isozymes are responsible for most of the nitrate reduction in barley seedlings. For all genotypes, nitrate assimilation rates in the dark were about 55% of the rates in light. Hypotheses that nitrate reductase has direct or indirect roles in nitrate uptake were not supported by this study. Induction of nitrate transporters and the kinetics of net nitrate uptake were the same for all four genotypes indicating that neither nitrate reductase isozyme has a direct role in nitrate uptake in barley seedlings.

Comparative sodium transport patterns provide clues for understanding salinity and metal responses in aquatic insects.

PubMed

Scheibener, S A; Richardi, V S; Buchwalter, D B

2016-02-01

The importance of insects in freshwater ecosystems has led to their extensive use in ecological monitoring programs. As freshwater systems are increasingly challenged by salinization and metal contamination, it is important to understand fundamental aspects of aquatic insect physiology (e.g., osmoregulatory processes) that contribute to insect responses to these stressors. Here we compared the uptake dynamics of Na as NaCl, NaHCO3 and Na2SO4 in the caddisfly Hydropsyche betteni across a range of Na concentrations (0.06-15.22 mM) encompassing the vast majority of North American freshwater ecosystems. Sulfate as the major anion resulted in decreased Na uptake rates relative to the chloride and bicarbonate salts. A comparison of Na (as NaHCO3) turnover rates in the caddisfly Hydropsyche sparna and the mayfly Maccaffertium sp. revealed different patterns in the 2 species. Both species appeared to tightly regulate their whole body sodium concentrations (at ∼47±1.8 μmol/g wet wt) across a range of Na concentrations (0.06-15.22 mM) over 7 days. However, at the highest Na concentration (15.22 mM), Na uptake rates in H. sparna (419.1 μM Na g(-1) hr(-1) wet wt) appeared close to saturation while Na uptake rates in Maccaffertium sp. were considerably faster (715 g μM Na g(-1) hr(-1) wet wt) and appeared to not be close to saturation. Na efflux studies in H. sparna revealed that loss rates are commensurate with uptake rates and are responsive to changes in water Na concentrations. A comparison of Na uptake rates (at 0.57 mM Na) across 9 species representing 4 major orders (Ephemeroptera, Plecoptera, Trichoptera and Diptera) demonstrated profound physiological differences across species after accounting for the influence of body weight. Faster Na uptake rates were associated with species described as being sensitive to salinization in field studies. The metals silver (Ag) and copper (Cu), known to be antagonistic to Na uptake in other aquatic taxa did not generally exhibit this effect in aquatic insects. Ag only reduced Na uptake at extremely high concentrations, while Cu generally stimulated Na uptake in aquatic insects, rather than suppress it. These results help explain the lack of insect responses to dissolved metal exposures in traditional toxicity testing and highlight the need to better understand fundamental physiological processes in this ecologically important faunal group. Copyright © 2015 Elsevier B.V. All rights reserved.

Organic and inorganic nitrogen uptake by 21 dominant tree species in temperate and tropical forests.

PubMed

Liu, Min; Li, Changcheng; Xu, Xingliang; Wanek, Wolfgang; Jiang, Ning; Wang, Huimin; Yang, Xiaodong

2017-11-01

Evidence shows that many tree species can take up organic nitrogen (N) in the form of free amino acids from soils, but few studies have been conducted to compare organic and inorganic N uptake patterns in temperate and tropical tree species in relation to mycorrhizal status and successional state. We labeled intact tree roots by brief 15N exposures using field hydroponic experiments in a temperate forest and a tropical forest in China. A total of 21 dominant tree species were investigated, 8 in the temperate forest and 13 in the tropical forest. All investigated tree species showed highest uptake rates for NH4+ (ammonium), followed by glycine and NO3- (nitrate). Uptake of NH4+ by temperate trees averaged 12.8 μg N g-1 dry weight (d.w.) root h-1, while those by tropical trees averaged 6.8 μg N g-1 d.w. root h-1. Glycine uptake rates averaged 3.1 μg N g-1 d.w. root h-1 for temperate trees and 2.4 μg N g-1 d.w. root h-1 for tropical trees. NO3- uptake was the lowest (averaging 0.8 μg N g-1 d.w. root h-1 for temperate trees and 1.2 μg N g-1 d.w. root h-1 for tropical trees). Uptake of NH4+ accounted for 76% of the total uptake of all three N forms in the temperate forest and 64% in the tropical forest. Temperate tree species had similar glycine uptake rates as tropical trees, with the contribution being slightly lower (20% in the temperate forest and 23% in the tropical forest). All tree species investigated in the temperate forest were ectomycorrhizal and all species but one in the tropical forest were arbuscular mycorrhizal (AM). Ectomycorrhizal trees showed significantly higher NH4+ and lower NO3- uptake rates than AM trees. Mycorrhizal colonization rates significantly affected uptake rates and contributions of NO3- or NH4+, but depended on forest types. We conclude that tree species in both temperate and tropical forests preferred to take up NH4+, with organic N as the second most important N source. These findings suggest that temperate and tropical forests demonstrate similar N uptake patterns although they differ in physiology of trees and soil biogeochemical processes. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Human Papillomavirus Vaccine Uptake in Adolescent Boys: An Evidence Review.

PubMed

Voss, Danielle S; Wofford, Linda G

2016-10-01

Despite evidence-based guidelines recommending routine vaccination against human papillomavirus (HPV) for adolescent boys, ages 11-12 years, vaccine uptake among this population remains low. To examine reasons for low HPV quadrivalent vaccine uptake and methods available to increase vaccine uptake among adolescent males, ages 11-12 years. Of 341 identified studies, 30 were included from three databases. The 30 studies were grouped into six categories: population-specific, problem-specific, educational interventions, theory-specific, political implications, and foundational guidelines and Websites. Among eight studies, low vaccine uptake was attributed to lack of parental, adolescent, and physician knowledge of HPV4 vaccine availability and recommendations. HPV4 vaccine educational interventions for parents and adolescents were the most effective for promoting vaccine uptake. Theory applications and gain-framed messages were shown to be effective for assessing HPV vaccine attitudes and perceptions. Political implication studies reveal the need for political and financial measures to encourage HPV vaccine acceptability among the population. To promote HPV vaccine uptake among adolescent males, providers must remain current with HPV vaccine recommendations and offer parental and adolescent HPV education focusing on benefits of vaccine acceptance and risks of vaccine refusal. The results of this review inform our understanding of effective educational strategies to positively impact HPV vaccine uptake in adolescent males. Based on this review, clinicians can employ several evidence-based educational strategies to facilitate HPV vaccine uptake. © 2016 Sigma Theta Tau International.

Atmospheric nitrous oxide uptake in boreal spruce forest soil

NASA Astrophysics Data System (ADS)

Siljanen, Henri; Welti, Nina; Heikkinen, Juha; Biasi, Christina; Martikainen, Pertti

2017-04-01

Nitrous oxide (N2O) uptake from the atmosphere has been found in forest soils but environmental factors controlling the uptake and its atmospheric impact are poorly known. We measured N2O fluxes over growing season in a boreal spruce forest having control plots and plots with long nitrogen fertilization history. Also methane (CH4) fluxes were measured to compare the atmospheric impact of N2O and CH4fluxes. Soil chemical and physical characteristics and climatic conditions were measured as background data. Nitrous oxide consumption and uptake mechanisms were measured in complementary laboratory incubation experiments using stable isotope approaches. Gene transcript numbers of nitrous oxide reductase (nosZ) I and II genes were quantified along the incubation with elevated N2O atmosphere. The spruce forests without fertilization history showed highest N2O uptake rates whereas pine forest had low emissions. Nitrous oxide uptake correlated positively with soil moisture, high soil silt content, and low temperature. Nitrous oxide uptake varied seasonally, being highest in spring and autumn when temperature was low and water content was high. The spruce forest was sink for CH4.Methane fluxes were decoupled from the N2O fluxes (i.e. when the N2O uptake was high the CH4 uptake was low). By using GWP approach, the cooling effect of N2O uptake was on average 30% of the cooling effect of CH4 uptake in spruce forest without fertilization. Anoxic conditions promoted higher N2O consumption rates in all soils. Gene transcription of nosZ-I genes were activated at beginning of the incubation. However, atypical/clade-II nosZ was not detected. These results suggests, that also N2O uptake rates have to be considered when accounting for the GHG budget of spruce forests.

Immunological Evidence for the Existence of a Carrier Protein for Sucrose Transport in Tonoplast Vesicles from Red Beet (Beta vulgaris L.) Root Storage Tissue.

PubMed Central

Getz, H. P.; Grosclaude, J.; Kurkdjian, A.; Lelievre, F.; Maretzki, A.; Guern, J.

1993-01-01

Monoclonal antibodies were raised in mice against a highly purified tonoplast fraction from isolated red beet (Beta vulgaris L. ssp. conditiva) root vacuoles. Positive hybridoma clones and sub-clones were identified by prescreening using an enzyme-linked immunosorbent assay (ELISA) and by postscreening using a functional assay. This functional assay consisted of testing the impact of hybridoma supernatants and antibody-containing ascites fluids on basal and ATP-stimulated sugar uptake in vacuoles, isolated from protoplasts, as well as in tonoplast vesicles, prepared from tissue homogenates of red beet roots. Antibodies from four clones were particularly positive in ELISAs and they inhibited sucrose uptake significantly. These antibodies were specific inhibitors of sucrose transport, but they exhibited relatively low membrane and species specificity since uptake into red beet root protoplasts and sugarcane tonoplast vesicles was inhibited as well. Fast protein liquid chromatography assisted size exclusion chromatography on Superose 6 columns yielded two major peaks in the 55 to 65-kD regions and in the 110- to 130-kD regions of solubilized proteins from red beet root tonoplasts, which reacted positively in immunoglobulin-M(IgM)-specific ELISAs with anti-sugarcane tonoplast monoclonal IgM antibodies. Only reconstituted proteoliposomes containing polypeptides from the 55- to 65-kD band took up [14C]-sucrose with linear rates for 2 min, suggesting that this fraction contains the tonoplast sucrose carrier. PMID:12231863

Quantitative Impact of Plasma Clearance and Down-regulation on GLP-1 Receptor Molecular Imaging.

PubMed

Zhang, Liang; Thurber, Greg M

2016-02-01

Quantitative molecular imaging of beta cell mass (BCM) would enable early detection and treatment monitoring of type 1 diabetes. The glucagon-like peptide-1 (GLP-1) receptor is an attractive target due to its beta cell specificity and cell surface location. We quantitatively investigated the impact of plasma clearance and receptor internalization on targeting efficiency in healthy B6 mice. Four exenatide-based probes were synthesized that varied in molecular weight, binding affinity, and plasma clearance. The GLP-1 receptor internalization rate and in vivo receptor expression were quantified. Receptor internalization (54,000 receptors/cell in vivo) decreased significantly within minutes, reducing the benefit of a slower-clearing agent. The multimers and albumin binding probes had higher kidney and liver uptake, respectively. Slow plasma clearance is beneficial for GLP-1 receptor peptide therapeutics. However, for exendin-based imaging of islets, down-regulation of the GLP-1 receptor and non-specific background uptake result in a higher target-to-background ratio for fast-clearing agents.

Quantitative Impact of Plasma Clearance and Down-regulation on GLP-1 Receptor Molecular Imaging

PubMed Central

Zhang, Liang; Thurber, Greg M.

2016-01-01

Purpose Quantitative molecular imaging of beta cell mass (BCM) would enable early detection and treatment monitoring of type-1 diabetes. The glucagon like peptide-1 (GLP-1) receptor is an attractive target due to its beta cell specificity and cell surface location. We quantitatively investigated the impact of plasma clearance and receptor internalization on targeting efficiency in healthy B6 mice. Procedures Four exenatide-based probes were synthesized that varied in molecular weight, binding affinity, and plasma clearance. The GLP-1 receptor internalization rate and in vivo receptor expression were quantified. Results Receptor internalization (54,000 receptors/cell in vivo) decreased significantly within minutes, reducing the benefit of a slower clearing agent. The multimers and albumin binding probes had higher kidney and liver uptake, respectively. Conclusions Slow plasma clearance is beneficial for GLP-1 receptor peptide therapeutics. However, for exendin-based imaging of islets, downregulation of the GLP-1 receptor and non-specific background uptake result in a higher TBR for fast-clearing agents. PMID:26194012

Aquatic Plant Control Research Program: Chemical Control of Hydrilla in Flowing Water: Herbicide Uptake Characteristics and Concentrations versus Exposure.

DTIC Science & Technology

1988-03-01

and di ecious hydrilla with diquat, endothall, and fluridone , and (c) to examine time-course uptak characteristics of these herbicides by hydrilla...diquat is effective in hydrilla control at a lower rate than is endothall. Uptake of fluridone by excised hydrilla tissue was linear with time when...ambient fluridone levels were 0.1 to 0.5 mg/i. However, a biphasic uptake curve was obtained at the high treatment rate of 1.0 mg/i fluridone . At this

Microbial Enzyme Activity, Nutrient Uptake, and Nutrient Limitation in Forested Streams

EPA Science Inventory

We measured NH4 + and PO4 -3 uptake length (Sw), uptake velocity (Vf), uptake rate (U), biofilm enzyme activity (BEA), and channel geomorphology in streams draining forested catchments in the Northwestern (Northern California Coast Range and Cascade Mountains) and Southeastern (A...

The link of feast-phase dissolved oxygen (DO) with substrate competition and microbial selection in PHA production.

PubMed

Wang, Xiaofei; Oehmen, Adrian; Freitas, Elisabete B; Carvalho, Gilda; Reis, Maria A M

2017-04-01

Polyhydroxyalkanoates (PHAs) are biobased and biodegradable polyesters with the potential to replace conventional plastics. Aeration requires large amounts of energy in PHA production by mixed microbial cultures (MMCs), particularly during the feast phase due to substrate uptake. The objective of this study was to investigate the impact of DO concentrations on microbial selection, substrate competition and PHA production performance by MMCs. This represents the first study investigating DO impact on PHA production while feeding the multiple volatile fatty acids (VFAs) typically encountered in real fermented feedstocks, as well as the substrate preferences at different DO levels. Efficient microbial cultures were enriched under both high (3.47 ± 1.12 mg/L) and low (0.86 ± 0.50 mg/L) DO conditions in the feast phase containing mostly the same populations but with different relative abundance. The most abundant microorganisms in the two MMCs were Plasticicumulans, Zoogloea, Paracoccus, and Flavobacterium. Butyrate and valerate were found to be the preferred substrates as compared to acetate and propionate regardless of DO concentrations. In the accumulation step, the PHA storage capacity and yield were less affected by the change of DO levels when applying the culture selected under low DO in the feast phase (PHA storage capacity >60% and yield > 0.9 Cmol PHA/Cmol VFA). A high DO level is required for maximal PHA accumulation rates with the four VFAs (acetate, propionate, butyrate and valerate) present, due to the lower specific uptake rates of acetate and propionate under low DO conditions. However, butyrate and valerate specific uptake rates were less impacted by DO levels and hence low DO for PHA accumulation may be effective when feed is composed of these substrates only. Copyright © 2017 Elsevier Ltd. All rights reserved.

Experimentally validated mathematical model of analyte uptake by permeation passive samplers.

PubMed

Salim, F; Ioannidis, M; Górecki, T

2017-11-15

A mathematical model describing the sampling process in a permeation-based passive sampler was developed and evaluated numerically. The model was applied to the Waterloo Membrane Sampler (WMS), which employs a polydimethylsiloxane (PDMS) membrane as a permeation barrier, and an adsorbent as a receiving phase. Samplers of this kind are used for sampling volatile organic compounds (VOC) from air and soil gas. The model predicts the spatio-temporal variation of sorbed and free analyte concentrations within the sampler components (membrane, sorbent bed and dead volume), from which the uptake rate throughout the sampling process can be determined. A gradual decline in the uptake rate during the sampling process is predicted, which is more pronounced when sampling higher concentrations. Decline of the uptake rate can be attributed to diminishing analyte concentration gradient within the membrane, which results from resistance to mass transfer and the development of analyte concentration gradients within the sorbent bed. The effects of changing the sampler component dimensions on the rate of this decline in the uptake rate can be predicted from the model. Performance of the model was evaluated experimentally for sampling of toluene vapors under controlled conditions. The model predictions proved close to the experimental values. The model provides a valuable tool to predict changes in the uptake rate during sampling, to assign suitable exposure times at different analyte concentration levels, and to optimize the dimensions of the sampler in a manner that minimizes these changes during the sampling period.

Influence of environmental conditions on the toxicokinetics of cadmium in the marine copepod Acartia tonsa.

PubMed

Pavlaki, Maria D; Morgado, Rui G; van Gestel, Cornelis A M; Calado, Ricardo; Soares, Amadeu M V M; Loureiro, Susana

2017-11-01

mMarine and estuarine ecosystems are highly productive areas that often act as a final sink for several pollutants, such as cadmium. Environmental conditions in these habitats can affect metal speciation, as well as its uptake and depuration by living organisms. The aim of this study was to assess cadmium uptake and depuration rates in the euryhaline calanoid copepod Acartia tonsa under different pH, salinity and temperature conditions. Cadmium speciation did not vary with changing pH or temperature, but varied with salinity. Free Cd 2+ ion activity increased with decreasing salinities resulting in increased cadmium concentrations in A. tonsa. However, uptake rate, derived using free Cd 2+ ion activity, showed no significant differences at different salinities indicating a simultaneous combined effect of Cd 2+ speciation and metabolic rates for osmoregulation. Cadmium concentration in A. tonsa and uptake rate increased with increasing pH, showing a peak at the intermediate pH of 7.5, while depuration rate fluctuated, thus suggesting that both parameters are mediated by metabolic processes (to maintain homeostasis at pH levels lower than normal) and ion competition at membrane binding sites. Cadmium concentration in A. tonsa, uptake and depuration rates increased with increasing temperature, a trend that can be attributed to an increase in metabolic energy demand at higher temperatures. The present study shows that cadmium uptake and depuration rates in the marine copepod A. tonsa is mostly affected by biological processes, mainly driven by metabolic mechanisms, and to a lesser extent by metal speciation in the exposure medium. Copyright © 2017 Elsevier Inc. All rights reserved.

[Kinetics of uptake of phosphates and nitrates by marine multicellular algae Gelidium latifolium (Grev.) Born. et Thur].

PubMed

Silkin, V A; Chubchikova, I N

2007-01-01

We studied nonstationary kinetics of the uptake of phosphates and nitrates by the red marine algae Gelidium latifolium (Grev.) Born et Thur. and calculated constants of the Michaelis-Menten equation for these elements. In the area of 0-3 microM, the kinetics of phosphate consumption had the following coefficients: maximum rate of uptake 0.8 micromol/(g x h), constant of half-saturation 1.745 microM. For nitrate nitrogen at 0-30 microM, an adaptive strategy of uptake kinetics was noted with change of the equation parameters with time: after 1 h, the maximum rate of uptake was 5.1 micromol/(g x h) and constant of half-saturation 19 gM, while within 2 h, the maximum rate of uptake significantly increased. This could be related to the synthesis of nitrate reductase. Coupled with the uptake of nitrates, nonstationary kinetics of the release of nitrates in the surrounding medium had a one-peak pattern: the maximum concentration of nitrites in the medium and the time of its achievement increased with the initial concentration of nitrates. The maximum concentration of nitrites was 6 to 14% of the initial concentration in the medium.

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).

[Effects of nitrogen application rate on potassium uptake and utilization of direct-seeded cotton after wheat harvest].

PubMed

Zhang, Guo Wei; Yang, Chang Qin; Liu, Rui Xian; Zhang, Lei; Ni, Wan Chao

2016-10-01

By using cotton cultivar CCRI-50 as material, field experiments were conducted in the summer seasons of 2013 and 2014 at the experimental station of Jiangsu Academy of Agricultural Sciences (Nanjing, China) to study the effects of different nitrogen application rates (0, 60, 120, 150, 180 and 240 kg N·hm -2 ) on the potassium uptake and utilization of the cotton plant that was direct-seeded after wheat harvest. Data suggested that the elevated nitrogen application rates increased the cotton potassium uptake of all growth stages, and the largest increment was observed at the peak flowering-boll opening stage. Nitrogen application also changed the uptake percentage of potassium uptake of each stage, i.e., the percentage of potassium uptake decreased in the stage from seedling to peak flowering, while increased in the stage from peak flowering to boll maturing. In addition, the elevated nitrogen applications reduced the decreasing rate of nitrogen concentration in upper fruiting branches, but promoted the decreasing rate in middle and low fruiting branches at later growth stages. As the nitrogen application rate increased, the marginal effect of potassium uptake (promoted amount of potassium uptake due to 1 kg increase of N application) increased first and then decreased, and the lint production efficiency of potassium descended steadily. In cotton plants that were direct-seeded after wheat harvest, potassium and biomass were mainly accumulated in the lower and middle fruiting branches. At the 150 and 180 kg N·hm -2 application levels, much more potassium was allocated to the reproductive organs and the characters and the eigenvalues of simulated curves of potassium concentration and total potassium accumulation were more optimized than those at the higher or the lower N application levels. At the high nitrogen application (more than 180 kg N·hm -2 ) level, the marginal effect of potassium uptake and lint production efficiency decreased, and at the lower nitrogen application (less than 150 kg N·hm -2 ) level, lint yield was lower due to the decrease of economic coefficient of biomass and potassium in the middle and low fruiting branches.

Achieving Lower Nitrogen Balance and Higher Nitrogen Recovery Efficiency Reduces Nitrous Oxide Emissions in North America's Maize Cropping Systems

PubMed Central

Omonode, Rex A.; Halvorson, Ardell D.; Gagnon, Bernard; Vyn, Tony J.

2017-01-01

Few studies have assessed the common, yet unproven, hypothesis that an increase of plant nitrogen (N) uptake and/or recovery efficiency (NRE) will reduce nitrous oxide (N2O) emission during crop production. Understanding the relationships between N2O emissions and crop N uptake and use efficiency parameters can help inform crop N management recommendations for both efficiency and environmental goals. Analyses were conducted to determine which of several commonly used crop N uptake-derived parameters related most strongly to growing season N2O emissions under varying N management practices in North American maize systems. Nitrogen uptake-derived variables included total aboveground N uptake (TNU), grain N uptake (GNU), N recovery efficiency (NRE), net N balance (NNB) in relation to GNU [NNB(GNU)] and TNU [NNB(TNU)], and surplus N (SN). The relationship between N2O and N application rate was sigmoidal with relatively small emissions for N rates <130 kg ha−1, and a sharp increase for N rates from 130 to 220 kg ha−1; on average, N2O increased linearly by about 5 g N per kg of N applied for rates up to 220 kg ha−1. Fairly strong and significant negative relationships existed between N2O and NRE when management focused on N application rate (r2 = 0.52) or rate and timing combinations (r2 = 0.65). For every percentage point increase, N2O decreased by 13 g N ha−1 in response to N rates, and by 20 g N ha−1 for NRE changes in response to rate-by-timing treatments. However, more consistent positive relationships (R2 = 0.73–0.77) existed between N2O and NNB(TNU), NNB(GNU), and SN, regardless of rate and timing of N application; on average N2O emission increased by about 5, 7, and 8 g N, respectively, per kg increase of NNB(GNU), NNB(TNU), and SN. Neither N source nor placement influenced the relationship between N2O and NRE. Overall, our analysis indicated that a careful selection of appropriate N rate applied at the right time can both increase NRE and reduce N2O. However, N2O reduction benefits of optimum N rate-by-timing practices were achieved most consistently with management systems that reduced NNB through an increase of grain N removal or total plant N uptake relative to the total fertilizer N applied to maize. Future research assessing crop or N management effects on N2O should include N uptake parameter measurements to better understand N2O emission relationships to plant NRE and N uptake. PMID:28690623

Light Conditions Affect the Measurement of Oceanic Bacterial Production via Leucine Uptake

PubMed Central

Morán, Xosé Anxelu G.; Massana, Ramon; Gasol, Josep M.

2001-01-01

The effect of irradiance in the range of 400 to 700 nm or photosynthetically active radiation (PAR) on bacterial heterotrophic production estimated by the incorporation of 3H-leucine (referred to herein as Leu) was investigated in the northwestern Mediterranean Sea and in a coastal North Atlantic site, with Leu uptake rates ranging over 3 orders of magnitude. We performed in situ incubations under natural irradiance levels of Mediterranean samples taken from five depths around solar noon and compared them to incubations in the dark. In two of the three stations large differences were found between light and dark uptake rates for the surfacemost samples, with dark values being on average 133 and 109% higher than in situ ones. Data obtained in coastal North Atlantic waters confirmed that dark enclosure may increase Leu uptake rates more than threefold. To explain these differences, on-board experiments of Leu uptake versus irradiance were performed with Mediterranean samples from depths of 5 and 40 m. Incubations under a gradient of 12 to 1,731 μmol of photons m−2 s−1 evidenced a significant increase in incorporation rates with increasing PAR in most of the experiments, with dark-incubated samples departing from this pattern. These results were not attributed to inhibition of Leu uptake in the light but to enhanced bacterial response when transferred to dark conditions. The ratio of dark to light uptake rates increased as dissolved inorganic nitrogen concentrations decreased, suggesting that bacterial nutrient deficiency was overcome by some process occurring only in the dark bottles. PMID:11525969

Relation between the location of elements in the periodic table and tumor-uptake rate.

PubMed

Ando, A; Ando, I; Hiraki, T; Hisada, K

1985-01-01

The bipositive ions and anions, with few exceptions, indicated a low tumor uptake rate. On the other hand, compounds of Hg, Au and Bi, which have a strong binding power to protein, showed a high tumor uptake rate. As Hg2+, Au+ and Bi3+ are soft acids according to the classification of Lewis acids, it was thought that these ions would bind strongly to soft bases (R-SH, R-S-) present in tumor tissue. For many hard acids such as 85Sr2+, 67Ga3+, 181Hf4+, and 95Nb5+, tumor uptake rates are shown as a function of ionic potentials (valency/ionic radii) of the metal ions. Considering the present data and previously reported results, it was presumed that hard acids of trivalence, quadrivalence and pentavalence would replace calcium in the calcium salts of hard bases (calcium salts of acid mucopolysaccharides, etc.). Ionic potentials of alkaline metals and Tl were small, but the tumor-uptake rate of these elements indicated various values. As Ge and Sb are bound by covalent bonds to chloride, GeCl4 and SbCl3 behaved differently from many metallic compounds in tumor tissue.

Within-session responses to high-intensity interval training in spinal cord injury.

PubMed

Astorino, Todd Anthony; Thum, Jacob S

2018-02-01

Completion of high-intensity interval training (HIIT) increases maximal oxygen uptake and health status, yet its feasibility in persons with spinal cord injury is unknown. To compare changes in cardiorespiratory and metabolic variables between two interval training regimes and moderate intensity exercise. Nine adults with spinal cord injury (duration = 6.8 ± 6.2 year) initially underwent determination of peak oxygen uptake. During subsequent sessions, they completed moderate intensity exercise, HIIT, or sprint interval training. Oxygen uptake, heart rate, and blood lactate concentration were measured. Oxygen uptake and heart rate increased (p < 0.05) during both interval training sessions and were similar (p > 0.05) to moderate intensity exercise. Peak oxygen uptake and heart rate were higher (p < 0.05) with HIIT (90% peak oxygen uptake and 99% peak heart rate) and sprint interval training (80% peak oxygen uptake and 96% peak heart rate) versus moderate intensity exercise. Despite a higher intensity and peak cardiorespiratory strain, all participants preferred interval training versus moderate exercise. Examining long-term efficacy and feasibility of interval training in this population is merited, considering that exercise intensity is recognized as the most important variable factor of exercise programming to optimize maximal oxygen uptake. Implications for Rehabilitation Spinal cord injury (SCI) reduces locomotion which impairs voluntary physical activity, typically resulting in a reduction in peak oxygen uptake and enhanced chronic disease risk. In various able-bodied populations, completion of high-intensity interval training (HIIT) has been consistently reported to improve cardiorespiratory fitness and other health-related outcomes, although its efficacy in persons with SCI is poorly understood. Data from this study in 9 men and women with SCI show similar changes in oxygen uptake and heart in response to HIIT compared to a prolonged bout of aerobic exercise, although peak values were higher in response to HIIT. Due to the higher peak metabolic strain induced by HIIT as well as universal preference for this modality versus aerobic exercise as reported in this study, further work testing utility of HIIT in this population is merited.

Proximal Tubules Have the Capacity to Regulate Uptake of Albumin.

PubMed

Wagner, Mark C; Campos-Bilderback, Silvia B; Chowdhury, Mahboob; Flores, Brittany; Lai, Xianyin; Myslinski, Jered; Pandit, Sweekar; Sandoval, Ruben M; Wean, Sarah E; Wei, Yuan; Satlin, Lisa M; Wiggins, Roger C; Witzmann, Frank A; Molitoris, Bruce A

2016-02-01

Evidence from multiple studies supports the concept that both glomerular filtration and proximal tubule (PT) reclamation affect urinary albumin excretion rate. To better understand these roles of glomerular filtration and PT uptake, we investigated these processes in two distinct animal models. In a rat model of acute exogenous albumin overload, we quantified glomerular sieving coefficients (GSC) and PT uptake of Texas Red-labeled rat serum albumin using two-photon intravital microscopy. No change in GSC was observed, but a significant decrease in PT albumin uptake was quantified. In a second model, loss of endogenous albumin was induced in rats by podocyte-specific transgenic expression of diphtheria toxin receptor. In these albumin-deficient rats, exposure to diphtheria toxin induced an increase in albumin GSC and albumin filtration, resulting in increased exposure of the PTs to endogenous albumin. In this case, PT albumin reabsorption was markedly increased. Analysis of known albumin receptors and assessment of cortical protein expression in the albumin overload model, conducted to identify potential proteins and pathways affected by acute protein overload, revealed changes in the expression levels of calreticulin, disabled homolog 2, NRF2, angiopoietin-2, and proteins involved in ATP synthesis. Taken together, these results suggest that a regulated PT cell albumin uptake system can respond rapidly to different physiologic conditions to minimize alterations in serum albumin level. Copyright © 2016 by the American Society of Nephrology.

Proximal Tubules Have the Capacity to Regulate Uptake of Albumin

PubMed Central

Wagner, Mark C.; Campos-Bilderback, Silvia B.; Chowdhury, Mahboob; Flores, Brittany; Lai, Xianyin; Myslinski, Jered; Pandit, Sweekar; Sandoval, Ruben M.; Wean, Sarah E.; Wei, Yuan; Satlin, Lisa M.; Wiggins, Roger C.; Witzmann, Frank A.

2016-01-01

Evidence from multiple studies supports the concept that both glomerular filtration and proximal tubule (PT) reclamation affect urinary albumin excretion rate. To better understand these roles of glomerular filtration and PT uptake, we investigated these processes in two distinct animal models. In a rat model of acute exogenous albumin overload, we quantified glomerular sieving coefficients (GSC) and PT uptake of Texas Red-labeled rat serum albumin using two-photon intravital microscopy. No change in GSC was observed, but a significant decrease in PT albumin uptake was quantified. In a second model, loss of endogenous albumin was induced in rats by podocyte-specific transgenic expression of diphtheria toxin receptor. In these albumin-deficient rats, exposure to diphtheria toxin induced an increase in albumin GSC and albumin filtration, resulting in increased exposure of the PTs to endogenous albumin. In this case, PT albumin reabsorption was markedly increased. Analysis of known albumin receptors and assessment of cortical protein expression in the albumin overload model, conducted to identify potential proteins and pathways affected by acute protein overload, revealed changes in the expression levels of calreticulin, disabled homolog 2, NRF2, angiopoietin-2, and proteins involved in ATP synthesis. Taken together, these results suggest that a regulated PT cell albumin uptake system can respond rapidly to different physiologic conditions to minimize alterations in serum albumin level. PMID:26054544

High affinity choline uptake (HACU) and choline acetyltransferase (ChAT) activity in neuronal cultures for mechanistic and drug discovery studies

PubMed Central

Ray, Balmiki; Bailey, Jason A.; Simon, Jay R.; Lahiri, Debomoy K.

2012-01-01

Acetylcholine (ACh) is the neurotransmitter used by cholinergic neurons at the neuromuscular junction and in parasympathetic nerve terminals in the periphery, as well as important memory-related circuits in the brain and also takes part in several critical functions. ACh is synthesized from choline and acetyl coenzyme-A by the enzyme choline acetyltransferase (ChAT). The formation of acetylcholine in cholinergic nerve terminals requires both the transport of choline into the cells from the extracellular space, and the activity of ChAT. High affinity choline uptake (HACU) represents the majority of choline uptake into the nerve terminal, and is the acutely regulated, rate-limiting step in ACh synthesis. The HACU component of choline uptake can be differentiated from non-specific choline uptake by inhibition of the choline transporter with hemicholinium. Several methods have been described previously to measure HACU and ChAT simultaneously in synaptosomes, but a well-documented protocol for cultured cells is lacking. We describe a procedure to simultaneously measure HACU and ChAT in cultured cells by simple radionuclide-based techniques. In this procedure we have quantitatively determined HACU and ChAT activity in cholinergically differentiated human neuroblastoma (SK-N-SH) cells. These simple methods can be used for neurochemical and drug discovery studies relevant to several disorders including Alzheimer’s disease, myasthenia gravis, and cardiovascular disease. PMID:22752895

Effect of specific plant-growth-promoting rhizobacteria (PGPR) on growth and uptake of neonicotinoid insecticide thiamethoxam in corn (Zea mays L.) seedlings.

PubMed

Myresiotis, Charalampos K; Vryzas, Zisis; Papadopoulou-Mourkidou, Euphemia

2015-09-01

Corn (Zea mays L.) is one of the most important cereal crops in the world and is used for food, feed and energy. Inoculation with plant-growth-promoting rhizobacteria (PGPR) would reduce the use of chemical fertilisers and pesticides and could be suggested as an alternative practice for sustainable production of corn in modern agricultural systems. In this study, the effect of two Bacillus PGPR formulated products, Companion (B. subtilis GB03) and FZB24 (B. subtilis FZB24), on corn growth and root uptake of insecticide thiamethoxam was investigated. All bacterial treatments enhanced root biomass production by 38-65% compared with the uninoculated control, with no stimulatory effect of PGPR on above-ground biomass of corn. The uptake results revealed that, in plants inoculated with the PGPR B. subtilis FZB24 and B. subtilis GB03, singly or in combination, the uptake and/or systemic translocation of thiamethoxam in the above-ground corn parts was significantly higher at the different growth ages compared with the control receiving no bacterial treatment. The findings suggest that the PGPR-elicited enhanced uptake of thiamethoxam could lead to improved efficiency of thiamethoxam using reduced rates of pesticides in combination with PGPR as an alternative crop protection technique. © 2014 Society of Chemical Industry.

Increased presynaptic regulation of dopamine neurotransmission in the nucleus accumbens core following chronic ethanol self-administration in female macaques

PubMed Central

Siciliano, Cody A.; Calipari, Erin S.; Yorgason, Jordan T.; Lovinger, David M.; Mateo, Yolanda; Jimenez, Vanessa A.; Helms, Christa M.; Grant, Kathleen A.; Jones, Sara R.

2016-01-01

Rationale Hypofunction of striatal dopamine neurotransmission, or hypodopaminergia, is a consequence of excessive ethanol use, and is hypothesized to be a critical component of alcoholism, driving alcohol intake in an attempt to restore dopamine levels; however, the neurochemical mechanisms involved in these dopaminergic deficiencies are unknown. Objective Here we examined the specific dopaminergic adaptations that produce hypodopaminergia and contribute to alcohol use disorders using direct, sub-second measurements of dopamine signaling in nonhuman primates following chronic ethanol self-administration. Methods Female rhesus macaques completed one year of daily (22 hr/day) ethanol self-administration. Subsequently, fast-scan cyclic voltammetry was used in nucleus accumbens core brain slices to determine alterations in dopamine terminal function, including release and uptake kinetics, and sensitivity to quinpirole (D2/D3 dopamine receptor agonist) and U50,488 (kappa-opioid receptor agonist) induced inhibition of dopamine release. Results Ethanol drinking greatly increased uptake rates, which were positively correlated with lifetime ethanol intake. Furthermore, the sensitivity of dopamine D2/D3 autoreceptors and kappa-opioid receptors, which both act as negative regulators of presynaptic dopamine release, were moderately and robustly enhanced in ethanol drinkers. Conclusions Greater uptake rates and sensitivity to D2-type autoreceptor and kappa-opioid receptor agonists could converge to drive a hypodopaminergic state, characterized by reduced basal dopamine and an inability to mount appropriate dopaminergic responses to salient stimuli. Together, we outline the specific alterations to dopamine signaling that may drive ethanol-induced hypofunction of the dopamine system, and suggest that the dopamine and dynorphin/kappa-opioid receptor systems may be efficacious pharmcotherapeutic targets in the treatment of alcohol use disorders. PMID:26892380

Increased presynaptic regulation of dopamine neurotransmission in the nucleus accumbens core following chronic ethanol self-administration in female macaques.

PubMed

Siciliano, Cody A; Calipari, Erin S; Yorgason, Jordan T; Lovinger, David M; Mateo, Yolanda; Jimenez, Vanessa A; Helms, Christa M; Grant, Kathleen A; Jones, Sara R

2016-04-01

Hypofunction of striatal dopamine neurotransmission, or hypodopaminergia, is a consequence of excessive ethanol use and is hypothesized to be a critical component of alcoholism, driving alcohol intake in an attempt to restore dopamine levels; however, the neurochemical mechanisms involved in these dopaminergic deficiencies are not fully understood. Here we examined the specific dopaminergic adaptations that produce hypodopaminergia and contribute to alcohol use disorders using direct, sub-second measurements of dopamine signaling in nonhuman primates following chronic ethanol self-administration. Female rhesus macaques completed 1 year of daily (22 h/day) ethanol self-administration. Subsequently, fast-scan cyclic voltammetry was used in nucleus accumbens core brain slices to determine alterations in dopamine terminal function, including release and uptake kinetics, and sensitivity to quinpirole (D2/D3 dopamine receptor agonist) and U50,488 (kappa opioid receptor agonist) induced inhibition of dopamine release. Ethanol drinking greatly increased uptake rates, which were positively correlated with lifetime ethanol intake. Furthermore, the sensitivity of dopamine D2/D3 autoreceptors and kappa opioid receptors, which both act as negative regulators of presynaptic dopamine release, was moderately and robustly enhanced in ethanol drinkers. Greater uptake rates and sensitivity to D2-type autoreceptor and kappa opioid receptor agonists could converge to drive a hypodopaminergic state, characterized by reduced basal dopamine and an inability to mount appropriate dopaminergic responses to salient stimuli. Together, we outline the specific alterations to dopamine signaling that may drive ethanol-induced hypofunction of the dopamine system and suggest that the dopamine and dynorphin/kappa opioid receptor systems may be efficacious pharmacotherapeutic targets in the treatment of alcohol use disorders.

Effect of summer throughfall exclusion, summer drought, and winter snow cover on methane fluxes in a temperate forest soil

USGS Publications Warehouse

Borken, W.; Davidson, E.A.; Savage, K.; Sundquist, E.T.; Steudler, P.

2006-01-01

Soil moisture strongly controls the uptake of atmospheric methane by limiting the diffusion of methane into the soil, resulting in a negative correlation between soil moisture and methane uptake rates under most non-drought conditions. However, little is known about the effect of water stress on methane uptake in temperate forests during severe droughts. We simulated extreme summer droughts by exclusion of 168 mm (2001) and 344 mm (2002) throughfall using three translucent roofs in a mixed deciduous forest at the Harvard Forest, Massachusetts, USA. The treatment significantly increased CH4 uptake during the first weeks of throughfall exclusion in 2001 and during most of the 2002 treatment period. Low summertime CH4 uptake rates were found only briefly in both control and exclusion plots during a natural late summer drought, when water contents below 0.15 g cm-3 may have caused water stress of methanotrophs in the A horizon. Because these soils are well drained, the exclusion treatment had little effect on A horizon water content between wetting events, and the effect of water stress was smaller and more brief than was the overall treatment effect on methane diffusion. Methane consumption rates were highest in the A horizon and showed a parabolic relationship between gravimetric water content and CH4 consumption, with maximum rate at 0.23 g H2O g-1 soil. On average, about 74% of atmospheric CH4 was consumed in the top 4-5 cm of the mineral soil. By contrast, little or no CH4 consumption occurred in the O horizon. Snow cover significantly reduced the uptake rate from December to March. Removal of snow enhanced CH4 uptake by about 700-1000%, resulting in uptake rates similar to those measured during the growing season. Soil temperatures had little effect on CH4 uptake as long as the mineral soil was not frozen, indicating strong substrate limitation of methanotrophs throughout the year. Our results suggest that the extension of snow periods may affect the annual rate of CH4 oxidation and that summer droughts may increase the soil CH4 sink of temperate forest soils. ?? 2005 Elsevier Ltd. All rights reserved.

Electric motor assisted bicycle as an aerobic exercise machine.

PubMed

Nagata, T; Okada, S; Makikawa, M

2012-01-01

The goal of this study is to maintain a continuous level of exercise intensity around the aerobic threshold (AT) during riding on an electric motor assisted bicycle using a new control system of electrical motor assistance which uses the efficient pedaling rate of popular bicycles. Five male subjects participated in the experiment, and the oxygen uptake was measured during cycling exercise using this new pedaling rate control system of electrical motor assistance, which could maintain the pedaling rate within a specific range, similar to that in previous type of electrically assisted bicycles. Results showed that this new pedaling rate control system at 65 rpm ensured continuous aerobic exercise intensity around the AT in two subjects, and this intensity level was higher than that observed in previous type. However, certain subjects were unable to maintain the expected exercise intensity because of their particular cycling preferences such as the pedaling rate. It is necessary to adjust the specific pedaling rate range of the electrical motor assist control according to the preferred pedaling rate, so that this system becomes applicable to anyone who want continuous aerobic exercise.

Effects of calcium on hepatocyte iron uptake from transferrin, iron-pyrophosphate and iron-ascorbate.

PubMed

Nilsen, T

1991-10-16

Calcium stimulates hepatocyte iron uptake from transferrin, ferric-iron-pyrophosphate and ferrous-iron-ascorbate. Maximal stimulation of iron uptake is observed at 1-1.5 mM of extra-cellular calcium and the effect is reversible and immediate. Neither the receptor affinity for transferrin, nor the total amounts of transferrin associated with the cells or the rate of transferrin endocytosis are significantly affected by calcium. In the presence of calcium the rate of iron uptake of non-transferrin bound iron increases abruptly at approximate 17 degrees C and 27 degrees C and as assessed by Arrhenius plots, the activation energy is reduced in a calcium dependent manner at approx. 27 degrees C. At a similar temperature, i.e., between 25 degrees C and 28 degrees C, calcium increases the rates of cellular iron uptake from transferrin in a way that is not reflected in the rate of transferrin endocytosis. By the results of this study it is concluded that calcium increases iron transport across the plasma membrane by a mechanism dependent on membrane fluidity.

Correction for photobleaching in dynamic fluorescence microscopy: application in the assessment of pharmacokinetic parameters in ultrasound-mediated drug delivery

NASA Astrophysics Data System (ADS)

Derieppe, M.; Bos, C.; de Greef, M.; Moonen, C.; de Senneville, B. Denis

2016-01-01

We have previously demonstrated the feasibility of monitoring ultrasound-mediated uptake of a hydrophilic model drug in real time with dynamic confocal fluorescence microscopy. In this study, we evaluate and correct the impact of photobleaching to improve the accuracy of pharmacokinetic parameter estimates. To model photobleaching of the fluorescent model drug SYTOX Green, a photobleaching process was added to the current two-compartment model describing cell uptake. After collection of the uptake profile, a second acquisition was performed when SYTOX Green was equilibrated, to evaluate the photobleaching rate experimentally. Photobleaching rates up to 5.0 10-3 s-1 were measured when applying power densities up to 0.2 W.cm-2. By applying the three-compartment model, the model drug uptake rate of 6.0 10-3 s-1 was measured independent of the applied laser power. The impact of photobleaching on uptake rate estimates measured by dynamic fluorescence microscopy was evaluated. Subsequent compensation improved the accuracy of pharmacokinetic parameter estimates in the cell population subjected to sonopermeabilization.

Exchange of polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) between air and a mixed pasture sward.

PubMed

Barber, Jonathan L; Thomas, Gareth O; Bailey, Rebekah; Kerstiens, Gerhard; Jones, Kevin C

2004-07-15

To improve understanding of air-to-vegetation transfer of persistent organic pollutants (POPs), uptake and depuration of polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) between grass sward and air was investigated. Pasture swards were placed in fanned (2 m s(-1) wind speed) and unfanned conditions for a period of 20 days and sampled at intervals. Depuration was carried out after a short (4 days) and a long (14 days) exposure period. Prior to contamination, a mixed pasture sward at a semi-rural location contained sigmaPCN concentrations 15-20% of the sigmaPCB concentration. Uptake of both PCBs and PCNs was broadly linear in fanned and unfanned conditions over the 20-day period, i.e., the pasture did not reach equilibrium with the air. Uptake rates (fluxes) were greater under the fanned conditions. The difference in uptake rates between fanned and unfanned conditions increased with degree of chlorination for both PCBs and PCNs, ranging between a factor of 2 for tri-chlorinated PCBs and PCNs and a factor 5 for octa-chlorinated PCBs. Depuration results over the first hours were very scattered, showing an initial period of loss, followed by an increase in concentrations, possibly as a result of re-volatilization of PCBs from the soil in the trays, with consequent recapture by the overlying sward. Rapid clearance was observed over the following days, but depuration of PCBs and PCNs was still incomplete after 14 days, with 20% of the initial concentration of the sigmaPCBs and 10% of the sigmaPCNs retained by the sward. There was no difference in the proportion of POPs retained in the sward between the 4- and 14-day contamination treatments. POP-specific differences in the amount of compound "trapped" in leaves after contamination were observed. The results show that, although changes in the rate of air movement around a pasture have an effect on the uptake rate of POPs into the vegetation, plant-side resistance controls both the air-to-pasture and pasture-to-air exchange of gas-phase PCBs and PCNs; i.e., differences between plant species in cuticle composition and/or structure affecting the permeability of the cuticle are of greater importance than differences in leaf morphology affecting aerodynamic roughness.

AMPKα2 deficiency uncovers time dependency in the regulation of contraction-induced palmitate and glucose uptake in mouse muscle.

PubMed

Abbott, Marcia J; Bogachus, Lindsey D; Turcotte, Lorraine P

2011-07-01

AMP-activated protein kinase (AMPK) is a fuel sensor in skeletal muscle with multiple downstream signaling targets that may be triggered by increases in intracellular Ca(2+) concentration ([Ca(2+)]). The purpose of this study was to determine whether increases in intracellular [Ca(2+)] induced by caffeine act solely via AMPKα(2) and whether AMPKα(2) is essential to increase glucose uptake, fatty acid (FA) uptake, and FA oxidation in contracting skeletal muscle. Hindlimbs from wild-type (WT) or AMPKα(2) dominant-negative (DN) transgene mice were perfused during rest (n = 11), treatment with 3 mM caffeine (n = 10), or muscle contraction (n = 11). Time-dependent effects on glucose and FA uptake were uncovered throughout the 20-min muscle contraction perfusion period (P < 0.05). Glucose uptake rates did not increase in DN mice during muscle contraction until the last 5 min of the protocol (P < 0.05). FA uptake rates were elevated at the onset of muscle contraction and diminished by the end of the protocol in DN mice (P < 0.05). FA oxidation rates were abolished in the DN mice during muscle contraction (P < 0.05). The DN transgene had no effect on caffeine-induced FA uptake and oxidation (P > 0.05). Glucose uptake rates were blunted in caffeine-treated DN mice (P < 0.05). The DN transgene resulted in a greater use of intramuscular triglycerides as a fuel source during muscle contraction. The DN transgene did not alter caffeine- or contraction-mediated changes in the phosphorylation of Ca(2+)/calmodulin-dependent protein kinase I or ERK1/2 (P > 0.05). These data suggest that AMPKα(2) is involved in the regulation of substrate uptake in a time-dependent manner in contracting muscle but is not necessary for regulation of FA uptake and oxidation during caffeine treatment.

The ImmProve Project: Leveraging electronic health record data to promote immunization delivery

PubMed Central

Bundy, David G.; Persing, Nichole M.; Solomon, Barry S.; King, Tracy M.; Murakami, Peter; Thompson, Richard E.; Engineer, Lilly D.; Lehmann, Christoph U.; Miller, Marlene R.

2013-01-01

Objective Though an essential pediatric preventive service, immunizations are challenging to deliver reliably. Our objective was to measure the impact on pediatric immunization rates of providing clinicians with electronic health record-derived immunization prompting. Methods Operating in a large, urban, hospital-based pediatric primary care clinic, we evaluated 2 interventions to improve immunization delivery to children ages 2, 6, and 13 years: point-of-care, patient-specific electronic clinical decision support (CDS) when children overdue for immunizations presented for care and provider-specific bulletins listing children overdue for immunizations. Results Overall, the proportion of children up-to-date for a composite of recommended immunizations at ages 2, 6, and 13 years was not different in the intervention (CDS active) and historical control (CDS not active) periods; historical immunization rates were high. The proportion of children receiving 2 doses of hepatitis A immunization prior to their second birthday was significantly improved during the intervention period. Human papilloma virus (HPV) immunization delivery was low during both control and intervention periods and was unchanged for 13-year-olds. For 14-year-olds, however, 4 of the 5 highest quarterly rates of complete HPV immunization occurred in the final year of the intervention. Provider-specific bulletins listing children overdue for immunizations increased the likelihood of identified children receiving catch-up hepatitis A immunizations (hazard ratio: 1.32 [95% confidence interval (CI): 1.12–1.56]); results for HPV and the composite of recommended immunizations were of a similar magnitude but not statistically significant. Conclusions In our patient population, with high baseline uptake of recommended immunizations, electronic health record-derived immunization prompting had a limited effect on immunization delivery. Benefit was more clearly demonstrated for newer immunizations with lower baseline uptake. PMID:23726754

Improving immunization delivery using an electronic health record: the ImmProve project.

PubMed

Bundy, David G; Persing, Nichole M; Solomon, Barry S; King, Tracy M; Murakami, Peter N; Thompson, Richard E; Engineer, Lilly D; Lehmann, Christoph U; Miller, Marlene R

2013-01-01

Though an essential pediatric preventive service, immunizations are challenging to deliver reliably. Our objective was to measure the impact on pediatric immunization rates of providing clinicians with electronic health record-derived immunization prompting. Operating in a large, urban, hospital-based pediatric primary care clinic, we evaluated 2 interventions to improve immunization delivery to children ages 2, 6, and 13 years: point-of-care, patient-specific electronic clinical decision support (CDS) when children overdue for immunizations presented for care, and provider-specific bulletins listing children overdue for immunizations. Overall, the proportion of children up to date for a composite of recommended immunizations at ages 2, 6, and 13 years was not different in the intervention (CDS active) and historical control (CDS not active) periods; historical immunization rates were high. The proportion of children receiving 2 doses of hepatitis A immunization before their second birthday was significantly improved during the intervention period. Human papillomavirus (HPV) immunization delivery was low during both control and intervention periods and was unchanged for 13-year-olds. For 14-year-olds, however, 4 of the 5 highest quarterly rates of complete HPV immunization occurred in the final year of the intervention. Provider-specific bulletins listing children overdue for immunizations increased the likelihood of identified children receiving catch-up hepatitis A immunizations (hazard ratio 1.32; 95% confidence interval 1.12-1.56); results for HPV and the composite of recommended immunizations were of a similar magnitude but not statistically significant. In our patient population, with high baseline uptake of recommended immunizations, electronic health record-derived immunization prompting had a limited effect on immunization delivery. Benefit was more clearly demonstrated for newer immunizations with lower baseline uptake. Copyright © 2013 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

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.

MICROSCOPIC METABOLISM OF CALCIUM IN BONE. IV. Ca$sup 45$ DEPOSITION AND GROWTH RATE IN CANINE OSTEONS

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

Marshall, J.H.; Jowsey, J.; Rowland, R.E.

1959-02-01

The Ca/sup 45/ content of individual osteons in three dogs given single intravenous injections has been measured autoradiographically and correlated with osteon canal diameter measured from microradiographs. An osteon was found to contain up to 10/sup -6/ of the injected activity, its total activity per unit length being approximately proportional to the square of its canal diameter at the time of injection. The activities observed at 12 hours or 2 weeks after injection divided by the corresponding time integral of the blood specific activity yield an accretion rate for calcium at each canal diameter such that the half-diameter time formore » the canal of an average forming osteon in a rather wide distnibution is 3 plus or minus 1 weeks, which is consistent with direct observations of osteon growth. It is concluded that the intense concentrations or in vivo-deposited Ca/sup 45/ which we have observed in canine osteons 12 hours or more after injection are due to accretion of calcium in appositional growth at approximately the specific activity measured in the large veins. The nature of the Ca/sup 45/ uptake in osteons which have completed or arrested appositional growth before injection cannot be inferred from the present data, but such uptake is here of an order of magnitude less than that due to appositional growth. Comparison of calculated blood flow with observed osteon growth rate indieates that an osteon in the early stages of appositiona« less

Extracellular thiol-assisted selenium uptake dependent on the xc− cystine transporter explains the cancer-specific cytotoxicity of selenite

PubMed Central

Olm, Eric; Fernandes, Aristi P.; Hebert, Christina; Rundlöf, Anna-Klara; Larsen, Erik H.; Danielsson, Olof; Björnstedt, Mikael

2009-01-01

The selenium salt selenite (SeO32−) is cytotoxic in low to moderate concentrations, with a remarkable specificity for cancer cells resistant to conventional chemotherapy. Our data show that selenium uptake and accumulation, rather than intracellular events, are crucial to the specific selenite cytotoxicity observed in resistant cancer cells. We show that selenium uptake depends on extracellular reduction, and that the extracellular environment is a key factor specific to selenite cytotoxicity. The extracellular reduction is mediated by cysteine, and the efficacy is determined by the uptake of cystine by the xc− antiporter and secretion of cysteine by multidrug resistance proteins, both of which are frequently overexpressed by resistant cancer cells. This mechanism provides molecular evidence for the existence of an inverse relationship between resistance to conventional chemotherapy and sensitivity to selenite cytotoxicity, and highlights the great therapeutic potential in treating multidrug-resistant cancer. PMID:19549867

Estimating Children's Soil/Dust Ingestion Rates through ...

EPA Pesticide Factsheets

Background: Soil/dust ingestion rates are important variables in assessing children’s health risks in contaminated environments. Current estimates are based largely on soil tracer methodology, which is limited by analytical uncertainty, small sample size, and short study duration. Objectives: The objective was to estimate site-specific soil/dust ingestion rates through reevaluation of the lead absorption dose–response relationship using new bioavailability data from the Bunker Hill Mining and Metallurgical Complex Superfund Site (BHSS) in Idaho, USA. Methods: The U.S. Environmental Protection Agency (EPA) in vitro bioavailability methodology was applied to archived BHSS soil and dust samples. Using age-specific biokinetic slope factors, we related bioavailable lead from these sources to children’s blood lead levels (BLLs) monitored during cleanup from 1988 through 2002. Quantitative regression analyses and exposure assessment guidance were used to develop candidate soil/dust source partition scenarios estimating lead intake, allowing estimation of age-specific soil/dust ingestion rates. These ingestion rate and bioavailability estimates were simultaneously applied to the U.S. EPA Integrated Exposure Uptake Biokinetic Model for Lead in Children to determine those combinations best approximating observed BLLs. Results: Absolute soil and house dust bioavailability averaged 33% (SD ± 4%) and 28% (SD ± 6%), respectively. Estimated BHSS age-specific soil/du

Effects of filtration modes on membrane fouling behavior and treatment in submerged membrane bioreactor.

PubMed

Maqbool, Tahir; Khan, Sher Jamal; Lee, Chung-Hak

2014-11-01

Relaxation or backwashing is obligatory for effective operation of membrane module and intermittent aeration is helpful for nutrients removal. This study was performed to investigate effects of different filtration modes on membrane fouling behavior and treatment in membrane bioreactor (MBR) operated at three modes i.e., 12, 10 and 8min filtration and 3, 2, and 2min relaxation corresponding to 6, 5 and 4cycles/hour, respectively. Various parameters including trans-membrane pressure, specific cake resistance, specific oxygen uptake rate, nutrients removal and sludge dewaterability were examined to optimize the filtration mode. TMP profiles showed that MBR(8+2) with 8min filtration and 2min relaxation reduced the fouling rate and depicted long filtration time in MBR treating synthetic wastewater. MBR(12+3) was more efficient in organic and nutrients removal while denitrification rate was high in MBR(8+2). Copyright © 2014 Elsevier Ltd. All rights reserved.

Evaluation of a low-carbohydrate diet-based preparation protocol without fasting for cardiac PET/MR imaging.

PubMed

Nensa, Felix; Tezgah, E; Schweins, K; Goebel, J; Heusch, P; Nassenstein, K; Schlosser, T; Poeppel, T D

2017-06-01

Assessment of increased glucose uptake in inflammatory or malignant myocardial disease using PET/MRI relies on uptake suppression in normal myocardium. We evaluated the efficacy of a ≥24 hours high-fat, low-carbohydrate, and protein-permitted diet (HFLCPP) in combination with unfractionated heparin for suppression of "physiologic" myocardial glucose uptake. PET/MRI was successfully performed in 89 patients. HFLCPP was started ≥24 hours prior to PET/MRI. All patients received i.v. injection of unfractionated heparin (50 IU·kg -1 ) 15 minutes prior to FDG administration. Left ventricular FDG uptake was visually evaluated by two readers. Diffuse myocardial uptake exceeding liver uptake, isolated uptake in the lateral wall, or diffuse uptake in the entire circumference of the heart base were defined as failed suppression. Homogeneous myocardial uptake below liver uptake with/without focal uptake was defined as successful suppression. Success rate was 84%. Suppression was unsuccessful in 14 patients. No significant influence of gender (P = .40) or age (P = .21) was found. However, insufficient suppression was more common in patients younger than 45 years (20% vs 7%). PET/MR imaging completion rate was >97%. A HFLCPP diet in combination with unfractionated heparin was successfully implemented for cardiac PET/MRI and resulted in a sufficient suppression of myocardial FDG uptake in 84% of patients.

Uptake Kinetics of Arsenic Species in Rice Plants

PubMed Central

Abedin, Mohammed Joinal; Feldmann, Jörg; Meharg, Andy A.

2002-01-01

Arsenic (As) finds its way into soils used for rice (Oryza sativa) cultivation through polluted irrigation water, and through historic contamination with As-based pesticides. As is known to be present as a number of chemical species in such soils, so we wished to investigate how these species were accumulated by rice. As species found in soil solution from a greenhouse experiment where rice was irrigated with arsenate contaminated water were arsenite, arsenate, dimethylarsinic acid, and monomethylarsonic acid. The short-term uptake kinetics for these four As species were determined in 7-d-old excised rice roots. High-affinity uptake (0–0.0532 mm) for arsenite and arsenate with eight rice varieties, covering two growing seasons, rice var. Boro (dry season) and rice var. Aman (wet season), showed that uptake of both arsenite and arsenate by Boro varieties was less than that of Aman varieties. Arsenite uptake was active, and was taken up at approximately the same rate as arsenate. Greater uptake of arsenite, compared with arsenate, was found at higher substrate concentration (low-affinity uptake system). Competitive inhibition of uptake with phosphate showed that arsenite and arsenate were taken up by different uptake systems because arsenate uptake was strongly suppressed in the presence of phosphate, whereas arsenite transport was not affected by phosphate. At a slow rate, there was a hyperbolic uptake of monomethylarsonic acid, and limited uptake of dimethylarsinic acid. PMID:11891266

Heart rate response to submaximal and maximal workloads during running and swimming.

PubMed

Hauber, C; Sharp, R L; Franke, W D

1997-07-01

The purpose of the present study was to determine if common indexes of exercise intensity, assessed with land-based exercise, could be applied to swimming. Consequently, the heart rate (HR) and oxygen uptake (VO2) responses to submaximal and maximal treadmill running (TR) and free swimming (SW) in 11 fitness swimmers were assessed to determine if the responses to TR could be used to predict those of SW. A maximal graded exercise test using a discontinuous protocol was used for TR, while four graded submaximal 200 yd swims and one 400 yd maximal swim was used for SW. Rest periods were similar for each mode. Significantly lower (p < 0.05) peak values were found in SW compared to TR for both HR (174 +/- 3 vs 183 +/- 3 bt x min(-1)) and VO2 (3.58 +/- 0.18 vs 3.97 +/- 0.22 L x min(-1)), SW vs TR; +/- SE, respectively. However, regression analyses of submaximal HR vs VO2 for each subject revealed similar slopes for TR and SW (30.5 +/- 1.7 vs 29.9 +/- 3.5 bt x L(-1), p > 0.05) and similar intercepts (67.3 +/- 2.6 vs 66.5 +/- 11.5 bt x min(-1), p > 0.05). At the VO2 equivalent to 50% treadmill VO2max, the heart rate predicted from SW did not differ significantly from TR (118 +/- 5 vs 124 +/- 1 bt x min(-1), p > 0.05). This was also true at 85% treadmill VO2max (171 +/- 4 vs 166 +/- 3 bt x min(-1), SW vs TR, respectively; p > 0.05). These data suggest that peak heart rate and oxygen uptake appear to be mode specific, but exercising at a given submaximal oxygen uptake will elicit a similar heart rate regardless of the mode. Thus, target heart rate ranges designed for land-based exercise appear to be appropriate for fitness swimmers during swimming.

From experiments to simulations: tracing Na+ distribution around roots under different transpiration rates and salinity levels

NASA Astrophysics Data System (ADS)

Perelman, Adi; Jorda, Helena; Vanderborght, Jan; Pohlmeier, Andreas; Lazarovitch, Naftali

2017-04-01

When salinity increases beyond a certain threshold it will result in reduced crop yield at a fixed rate, according to Maas and Hoffman model (1976). Thus, there is a great importance of predicting salinization and its impact on crops. Current models do not consider the impact of environmental conditions on plants salt tolerance, even though these conditions are affecting plant water uptake and therefore salt accumulation around the roots. Different factors, such as transpiration rates, can influence the plant sensitivity to salinity by influencing salt concentrations around the roots. Better parametrization of a model can help improving predicting the real effects of salinity on crop growth and yield. The aim of this research is to study Na+ distribution around roots at different scales using different non-invasive methods, and study how this distribution is being affected by transpiration rate and plant water uptake. Results from tomato plants growing on Rhizoslides (capillary paper growth system), show that Na+ concentration is higher at the root- substrate interface, compared with the bulk. Also, Na+ accumulation around the roots decreased under low transpiration rate, which is supporting our hypothesis. Additionally, Rhizoslides enable to study roots' growth rate and architecture under different salinity levels. Root system architecture was retrieved from photos taken during the experiment and enabled us to incorporate real root systems into a simulation. To observe the correlation of root system architectures and Na+ distribution in three dimensions, we used magnetic resonance imaging (MRI). MRI provides fine resolution of Na+ accumulation around a single root without disturbing the root system. With time, Na+ was accumulating only where roots were found in the soil and later on around specific roots. These data are being used for model calibration, which is expected to predict root water uptake in saline soils for different climatic conditions and different soil water availabilities.

Changes in calcium uptake rate by rat cardiac mitochondria during postnatal development.

PubMed

Bassani, R A; Fagian, M M; Bassani, J W; Vercesi, A E

1998-10-01

Ca2+ uptake, transmembrane electrical potential (Deltapsim) and oxygen consumption were measured in isolated ventricular mitochondria of rats from 3 days to 5 months of age. Estimated values of ruthenium red-sensitive, succinate-supported maximal rate of Ca2+ uptake (Vmax, expressed as nmol Ca2+/min/mg protein) were higher in neonates and gradually fell during postnatal development (from 435+/-24 at 3-6 days, to 156+/-10 in adults,P<0.001), whereas K0.5 values (approximately 10 microM were not significantly affected by age. Under similar conditions, mitochondria from adults (5 months old) and neonates (4-6 days old) showed comparable state 4 (succinate and alpha-ketoglutarate as substrates) and state 3ADP (alpha-ketoglutarate-supported) respiration rates, as well as Deltapsim values (approximately-150 mV). Respiration-independent Deltapsim and Ca2+ uptake, supported by valinomycin-induced K+ efflux were also investigated at these ages. A transient Deltapsim (approximately -30 mV) was evoked by valinomycin in both neonatal and adult mitochondria. Respiration-independent Ca2+ uptake was also transient, but its initial rate was significantly higher in neonates than in adults (49. 4+/-10.0v 28.0+/-5.7 mmol Ca2+/min/mg protein,P<0.01). These results indicate that Ca2+ uptake capacity of rat cardiac mitochondria is remarkably high just after birth and declines over the first weeks of postnatal life, without change in apparent affinity of the transporter. Increased mitochondrial Ca2+ uptake rate in neonates appears to be related to the uniporter itself, rather than to modification of the driving force of the transport. Copyright 1998 Academic Press

Rate and predictors of human papillomavirus vaccine uptake among women who have sex with women in the United States, the National Health and Nutrition Examination Survey, 2009-2012.

PubMed

Makris, Nicole; Vena, Catherine; Paul, Sudeshna

2016-12-01

To examine rates and associated correlates of human papilloma virus vaccine uptake in women who have sex with women in the United States, and to determine whether they differ from those in women who do not have sex with women. Women who have sex with women are at risk for human papilloma virus infection but are less likely to receive preventive gynaecological services. Little research has been carried out to evaluate human papilloma virus vaccination rates and associated predictors of vaccination uptake in this population. Cross-sectional descriptive study. Data from two consecutive cohorts of the National Health and Nutrition Examination Survey conducted by the United States' Centers for Disease Control were analysed. The sample (N = 1105) consisted of women aged 18-26 years. There was no difference in human papilloma virus vaccine uptake between women who have sex with women and women who do not have sex with women. Overall, the vaccination rate was low (32·5%). Having health insurance and more education were significant predictors of vaccine uptake in women who have sex with women. Higher education and younger age were predictors in women who do not have sex with women. Vaccination rates of women are far lower than the national target of 80%. The predictors of vaccine uptake were different in women who have sex with women than for women who do not have sex with women. Women in their 20s (regardless of their sexual orientation) should be recognised as an undervaccinated population and require targeted interventions to improve vaccination uptake. © 2016 John Wiley & Sons Ltd.

Coral Uptake of Inorganic Phosphorus and Nitrogen Negatively Affected by Simultaneous Changes in Temperature and pH

PubMed Central

Godinot, Claire; Houlbrèque, Fanny

2011-01-01

The effects of ocean acidification and elevated seawater temperature on coral calcification and photosynthesis have been extensively investigated over the last two decades, whereas they are still unknown on nutrient uptake, despite their importance for coral energetics. We therefore studied the separate and combined impacts of increases in temperature and pCO2 on phosphate, ammonium, and nitrate uptake rates by the scleractinian coral S. pistillata. Three experiments were performed, during 10 days i) at three pHT conditions (8.1, 7.8, and 7.5) and normal temperature (26°C), ii) at three temperature conditions (26°, 29°C, and 33°C) and normal pHT (8.1), and iii) at three pHT conditions (8.1, 7.8, and 7.5) and elevated temperature (33°C). After 10 days of incubation, corals had not bleached, as protein, chlorophyll, and zooxanthellae contents were the same in all treatments. However, photosynthetic rates significantly decreased at 33°C, and were further reduced for the pHT 7.5. The photosynthetic efficiency of PSII was only decreased by elevated temperature. Nutrient uptake rates were not affected by a change in pH alone. Conversely, elevated temperature (33°C) alone induced an increase in phosphate uptake but a severe decrease in nitrate and ammonium uptake rates, even leading to a release of nitrogen into seawater. Combination of high temperature (33°C) and low pHT (7.5) resulted in a significant decrease in phosphate and nitrate uptake rates compared to control corals (26°C, pHT = 8.1). These results indicate that both inorganic nitrogen and phosphorus metabolism may be negatively affected by the cumulative effects of ocean warming and acidification. PMID:21949839

A model for planning local contraceptive services.

PubMed

Wilson, S

1989-09-01

Data were collected on abortion referral rates, single young maternity rates and uptake of contraceptive services in order to identify specific areas of unmet need in the Nottingham Health District. Comparisons were made between boroughs and in the City of Nottingham between electoral wards. There was a direct relationship between abortion rate, single young maternity rate and social disadvantage. Analysis of contraceptive usage suggested a more ineffective service in the inner city, which has implications for the more efficient use of resources in the future. Targeting of consumer acceptable services to residents of the inner city and teenagers in general was recommended as a result of the study. For future planning a more useful routine data set was developed to record the activity at family planning clinics.

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.

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

Synthesis and evaluation of a radiolabeled bis-zinc(II)-cyclen complex as a potential probe for in vivo imaging of cell death.

PubMed

Wang, Hongliang; Wu, Zhifang; Li, Sijin; Hu, Kongzhen; Tang, Ganghua

2017-04-01

The exposition of phosphatidylserine (PS) from the cell membrane is associated with most cell death programs (apoptosis, necrosis, autophagy, mitotic catastrophe, etc.), which makes PS an attractive target for overall cell death imaging. To this end, zinc(II) macrocycle coordination complexes with cyclic polyamine units as low-molecular-weight annexin mimics have a selective affinity for biomembrane surfaces enriched with PS, and are therefore useful for detection of cell death. In the present study, a 11 C-labeled zinc(II)-bis(cyclen) complex ( 11 C-CyclenZn2) was prepared and evaluated as a new positron emission tomography (PET) probe for cell death imaging. 11 C-CyclenZn2 was synthesized by methylation of its precursor, 4-methoxy-2,5-di-[10-methyl-1,4,7,10-tetraazacyclododecane-1,4,7-tricarboxylic acid tri-tert-butyl ester] phenol (Boc-Cyclen2) with 11 C-methyl triflate as a prosthetic group in acetone, deprotection by hydrolysis in aqueous HCl solution, and chelation with zinc nitrate. The cell death imaging capability of 11 C-CyclenZn2 was evaluated using in vitro cell uptake assays with camptothecin-treated PC-3 cells, biodistribution studies, and in vivo PET imaging in Kunming mice bearing S-180 fibrosarcoma. Starting from 11 C-methyl triflate, the total preparation time for 11 C-CyclenZn2 was ~40 min, with an uncorrected radiochemical yield of 12 ± 3% (based on 11 C-CH 3 OTf, n = 10), a radiochemical purity of greater than 95%, and the specific activity of 0.75-1.01 GBq/μmol. The cell death binding specificity of 11 C-CyclenZn2 was demonstrated by significantly different uptake rates in camptothecin-treated and control PC-3 cells in vitro. Inhibition experiments for 18 F-radiofluorinated Annexin V binding to apoptotic/necrotic cells illustrated the necessity of zinc ions for zinc(II)-bis(cyclen) complexation in binding cell death, and zinc(II)-bis(cyclen) complexe and Annexin V had not identical binding pattern with apoptosis/necrosis cells. Biodistribution studies of 11 C-CyclenZn2 revealed a fast clearance from blood, low uptake rates in brain and muscle tissue, and high uptake rates in liver and kidney, which provide the main metabolic route. PET imaging using 11 C-CyclenZn2 revealed that cyclophosphamide-treated mice (CP-treated group) exhibited a significant increase of uptake rate in the tumor at 60 min postinjection, compared with control mice (Control group). The results indicate that the ability of 11 C-CyclenZn2 to detect cell death is comparable to Annexin V, and it has potential as a PET tracer for noninvasive evaluation and monitoring of anti-tumor chemotherapy.

Simultaneous saccharification and co-fermentation of paper sludge to ethanol by Saccharomyces cerevisiae RWB222--Part I: kinetic modeling and parameters.

PubMed

Zhang, Jiayi; Shao, Xiongjun; Townsend, Oliver V; Lynd, Lee R

2009-12-01

A kinetic model was developed to predict batch simultaneous saccharification and co-fermentation (SSCF) of paper sludge by the xylose-utilizing yeast Saccharomyces cerevisiae RWB222 and the commercial cellulase preparation Spezyme CP. The model accounts for cellulose and xylan enzymatic hydrolysis and competitive uptake of glucose and xylose. Experimental results show that glucan and xylan enzymatic hydrolysis are highly correlated, and that the low concentrations of xylose encountered during SSCF do not have a significant inhibitory effect on enzymatic hydrolysis. Ethanol is found to not only inhibit the specific growth rate, but also to accelerate cell death. Glucose and xylose uptake rates were found to be competitively inhibitory, but this did not have a large impact during SSCF because the sugar concentrations are low. The model was used to evaluate which constants had the greatest impact on ethanol titer for a fixed substrate loading, enzyme loading, and fermentation time. The cellulose adsorption capacity and cellulose hydrolysis rate constants were found to have the greatest impact among enzymatic hydrolysis related constants, and ethanol yield and maximum ethanol tolerance had the greatest impact among fermentation related constants.

Uptake and loss kinetics of Cd, Cr and Zn in the bivalves Potamocorbula amurensis and Macoma balthica: Effects of size and salinity

USGS Publications Warehouse

Lee, B.-G.; Wallace, W.G.; Luoma, S.N.

1998-01-01

Radiotracer studies were employed to quantitatively compare the biokinetics of uptake from the dissolved phase (influx rates) and loss (efflux) between 2 bivalves, Potamocorbula amurensis and Macoma balthica, and among the metals Cd, Cr and Zn. Effects of salinity on influx rate were evaluated in these 2 highly euryhaline species as were effects of animal size on uptake and loss. Metal speciation and biological attributes interacted to differentiate bioaccumulation processes among metals and between species. Influx rates of the 3 metals (??g g-1 [dry wt] d-1) increased linearly with dissolved metal concentrations. Influx rates of Zn in both clams were 3 to 4x those for Cd and 15x those for Cr. However, influx on the basis of free ion activities would be faster for Cd than for Zn. Relative influx rates among the metals were similar in the 2 bivalves. But, absolute influx rates of all 3 metals were 4 to 5x greater in P. amurensis than in M. balthica, probably because of differences in biological attributes (i.e. clearance rate or gill surface area). As salinity was reduced from 30 to 5 psu, the influx rate of Cd for P. amurensis increased 4-fold and that for M. balthica increased 6-fold, consistent with expected changes in speciation. However the influx rates of Cr in both clams also increased 2.4-fold over the same range, indicating a biological contribution to the salinity effect. Influx rates of Zn were not significantly affected by salinity. Weight specific metal influx rates (??g g-1 [dry wt] d-1) were negatively correlated with the tissue dry weight of the clams, but most rate constants determining physiological turnover of assimilated metals were not affected by clam size. The exception was the rate constant for Cd loss, which resulted in faster turnover in large M. balthica than in smaller clams. The rate constant of loss for P. amurensis increased in the order of Cd (0.011 d-1) < Zn (0.027 d-1) < Cr (0.048 d-1). This was different from the hierarchy of rate constants for M. balthica: Zn (0.012 d-1) < Cd (0.018 d-1) < Cr (0.024 d-1).

Improved Cellular Specificity of Plasmonic Nanobubbles versus Nanoparticles in Heterogeneous Cell Systems

PubMed Central

Lukianova-Hleb, Ekaterina Y.; Ren, Xiaoyang; Constantinou, Pamela E.; Danysh, Brian P.; Shenefelt, Derek L.; Carson, Daniel D.; Farach-Carson, Mary C.; Kulchitsky, Vladimir A.; Wu, Xiangwei; Wagner, Daniel S.; Lapotko, Dmitri O.

2012-01-01

The limited specificity of nanoparticle (NP) uptake by target cells associated with a disease is one of the principal challenges of nanomedicine. Using the threshold mechanism of plasmonic nanobubble (PNB) generation and enhanced accumulation and clustering of gold nanoparticles in target cells, we increased the specificity of PNB generation and detection in target versus non-target cells by more than one order of magnitude compared to the specificity of NP uptake by the same cells. This improved cellular specificity of PNBs was demonstrated in six different cell models representing diverse molecular targets such as epidermal growth factor receptor, CD3 receptor, prostate specific membrane antigen and mucin molecule MUC1. Thus PNBs may be a universal method and nano-agent that overcome the problem of non-specific uptake of NPs by non-target cells and improve the specificity of NP-based diagnostics, therapeutics and theranostics at the cell level. PMID:22509318

Improved cellular specificity of plasmonic nanobubbles versus nanoparticles in heterogeneous cell systems.

PubMed

Lukianova-Hleb, Ekaterina Y; Ren, Xiaoyang; Constantinou, Pamela E; Danysh, Brian P; Shenefelt, Derek L; Carson, Daniel D; Farach-Carson, Mary C; Kulchitsky, Vladimir A; Wu, Xiangwei; Wagner, Daniel S; Lapotko, Dmitri O

2012-01-01

The limited specificity of nanoparticle (NP) uptake by target cells associated with a disease is one of the principal challenges of nanomedicine. Using the threshold mechanism of plasmonic nanobubble (PNB) generation and enhanced accumulation and clustering of gold nanoparticles in target cells, we increased the specificity of PNB generation and detection in target versus non-target cells by more than one order of magnitude compared to the specificity of NP uptake by the same cells. This improved cellular specificity of PNBs was demonstrated in six different cell models representing diverse molecular targets such as epidermal growth factor receptor, CD3 receptor, prostate specific membrane antigen and mucin molecule MUC1. Thus PNBs may be a universal method and nano-agent that overcome the problem of non-specific uptake of NPs by non-target cells and improve the specificity of NP-based diagnostics, therapeutics and theranostics at the cell level.

Comparative analysis of nitrite uptake and hemoglobin-nitrite reactions in erythrocytes: sorting out uptake mechanisms and oxygenation dependencies.

PubMed

Jensen, Frank B; Rohde, Sabina

2010-04-01

Nitrite uptake into red blood cells (RBCs) precedes its intracellular reactions with hemoglobin (Hb) that forms nitric oxide (NO) during hypoxia. We investigated the uptake of nitrite and its reactions with Hb at different oxygen saturations (So(2)), using RBCs with (carp and rabbit) and without (hagfish and lamprey) anion exchanger-1 (AE1) in the membrane, with the aim to unravel the mechanisms and oxygenation dependencies of nitrite transport. Added nitrite rapidly diffused into the RBCs until equilibrium. The distribution ratio of nitrite across the membrane agreed with that expected from HNO(2) diffusion and AE1-mediated facilitated NO(2)(-) diffusion. Participation of HNO(2) diffusion was emphasized by rapid transmembrane nitrite equilibration also in the natural AE1 knockouts. Following the equilibration, nitrite was consumed by reacting with Hb, which created a continued inward diffusion controlled by intracellular reaction rates. Changes in nitrite uptake with So(2), pH, or species were accordingly explained by corresponding changes in reaction rates. In carp, nitrite uptake rates increased linearly with decreasing So(2) over the entire So(2) range. In rabbit, nitrite uptake rates were highest at intermediate So(2), producing a bell-shaped relationship with So(2). Nitrite consumption increased approximately 10-fold with a 1 unit decrease in pH, as expected from the involvement of protons in the reactions with Hb. The reaction of nitrite with deoxyhemoglobin was favored over that with oxyhemoglobin at intermediate So(2). We propose a model for RBC nitrite uptake that involves both HNO(2) diffusion and AE1-mediated transport and that explains both the present and previous (sometimes puzzling) results.

[Effects of reduced N application rate on yield and nutrient uptake and utilization in maize-soybean relay strip intercropping system].

PubMed

Yong, Tai-Wen; Liu, Xiao-Ming; Wen-Yu, Liu; Su, Ben-Ying; Song, Chun; Yang, Feng; Wang, Xiao-Chun; Yang, Wen-Yu

2014-02-01

A field experiment with three N application rates (0, 180, 240 N kg x hm(-2), representing zero, reduced and conventional N application, respectively) and three planting patterns (maize monoculture, soybean monoculture and maize-soybean relay strip intercropping) was conducted to reveal the effects of cropping patterns and N application rates on yield, nutrient uptake and nitrogen use efficiency of maize and soybean. The results showed that the grain yield, N, P and K uptake and harvest index of the intercropped maize reduced slightly compared with the monoculture maize, however these indices of the intercropped soybean increased significantly compared with the monoculture. With the increase in nitrogen fertilizer application, the excellence of relay strip intercropping was weakened in the maize-soybean intercropping system. The grain yield, economic coefficient, N, P and K uptake, harvest index, N agronomy efficiency and N uptake efficiency of maize and soybean increased significantly at the reduced nitrogen rate (180 N kg x hm(-2)), but the rate of soil N contribution declined, compared with the conventional rate of N application by local farmers (240 N kg x hm(-2)). In the reduced nitrogen rate treatment, total soil N and P contents of the maize strip reduced, whereas the total soil N, P and K contents of soybean strip and the total K content of maize strip increased compared with the zero N application treatment. With the reduced N application, the annual total grain yield, N, P and K uptake of above-ground biomass in the maize-soybean relay strip intercropping system were higher than in the monoculture, and the land equivalent ratio (LER) was 2.28. N uptake efficiency of maize in the relay strip intercropping system was 20.2% higher than in the maize monoculture, and the index of soybean was 30.5% lower than in the monoculture. The rate of soil N contribution in the relay strip intercropping system was 20.0% and 8.8% lower than in the maize and soybean monoculture, respectively. The reduced N application in the maize-soybean relay strip intercropping system was helpful to promote annual grain yield and improve N utilization efficiency.

Nitrogen and phosphorus uptake rates of different species from a coral reef community after a nutrient pulse

PubMed Central

den Haan, Joost; Huisman, Jef; Brocke, Hannah J.; Goehlich, Henry; Latijnhouwers, Kelly R. W.; van Heeringen, Seth; Honcoop, Saskia A. S.; Bleyenberg, Tanja E.; Schouten, Stefan; Cerli, Chiara; Hoitinga, Leo; Vermeij, Mark J. A.; Visser, Petra M.

2016-01-01

Terrestrial runoff after heavy rainfall can increase nutrient concentrations in waters overlying coral reefs that otherwise experience low nutrient levels. Field measurements during a runoff event showed a sharp increase in nitrate (75-fold), phosphate (31-fold) and ammonium concentrations (3-fold) in waters overlying a fringing reef at the island of Curaçao (Southern Caribbean). To understand how benthic reef organisms make use of such nutrient pulses, we determined ammonium, nitrate and phosphate uptake rates for one abundant coral species, turf algae, six macroalgal and two benthic cyanobacterial species in a series of laboratory experiments. Nutrient uptake rates differed among benthic functional groups. The filamentous macroalga Cladophora spp., turf algae and the benthic cyanobacterium Lyngbya majuscula had the highest uptake rates per unit biomass, whereas the coral Madracis mirabilis had the lowest. Combining nutrient uptake rates with the standing biomass of each functional group on the reef, we estimated that the ammonium and phosphate delivered during runoff events is mostly taken up by turf algae and the two macroalgae Lobophora variegata and Dictyota pulchella. Our results support the often proposed, but rarely tested, assumption that turf algae and opportunistic macroalgae primarily benefit from episodic inputs of nutrients to coral reefs. PMID:27353576

Nitrogen and phosphorus uptake rates of different species from a coral reef community after a nutrient pulse

NASA Astrophysics Data System (ADS)

den Haan, Joost; Huisman, Jef; Brocke, Hannah J.; Goehlich, Henry; Latijnhouwers, Kelly R. W.; van Heeringen, Seth; Honcoop, Saskia A. S.; Bleyenberg, Tanja E.; Schouten, Stefan; Cerli, Chiara; Hoitinga, Leo; Vermeij, Mark J. A.; Visser, Petra M.

2016-06-01

Terrestrial runoff after heavy rainfall can increase nutrient concentrations in waters overlying coral reefs that otherwise experience low nutrient levels. Field measurements during a runoff event showed a sharp increase in nitrate (75-fold), phosphate (31-fold) and ammonium concentrations (3-fold) in waters overlying a fringing reef at the island of Curaçao (Southern Caribbean). To understand how benthic reef organisms make use of such nutrient pulses, we determined ammonium, nitrate and phosphate uptake rates for one abundant coral species, turf algae, six macroalgal and two benthic cyanobacterial species in a series of laboratory experiments. Nutrient uptake rates differed among benthic functional groups. The filamentous macroalga Cladophora spp., turf algae and the benthic cyanobacterium Lyngbya majuscula had the highest uptake rates per unit biomass, whereas the coral Madracis mirabilis had the lowest. Combining nutrient uptake rates with the standing biomass of each functional group on the reef, we estimated that the ammonium and phosphate delivered during runoff events is mostly taken up by turf algae and the two macroalgae Lobophora variegata and Dictyota pulchella. Our results support the often proposed, but rarely tested, assumption that turf algae and opportunistic macroalgae primarily benefit from episodic inputs of nutrients to coral reefs.

Nitrogen and phosphorus uptake rates of different species from a coral reef community after a nutrient pulse.

PubMed

den Haan, Joost; Huisman, Jef; Brocke, Hannah J; Goehlich, Henry; Latijnhouwers, Kelly R W; van Heeringen, Seth; Honcoop, Saskia A S; Bleyenberg, Tanja E; Schouten, Stefan; Cerli, Chiara; Hoitinga, Leo; Vermeij, Mark J A; Visser, Petra M

2016-06-29

Terrestrial runoff after heavy rainfall can increase nutrient concentrations in waters overlying coral reefs that otherwise experience low nutrient levels. Field measurements during a runoff event showed a sharp increase in nitrate (75-fold), phosphate (31-fold) and ammonium concentrations (3-fold) in waters overlying a fringing reef at the island of Curaçao (Southern Caribbean). To understand how benthic reef organisms make use of such nutrient pulses, we determined ammonium, nitrate and phosphate uptake rates for one abundant coral species, turf algae, six macroalgal and two benthic cyanobacterial species in a series of laboratory experiments. Nutrient uptake rates differed among benthic functional groups. The filamentous macroalga Cladophora spp., turf algae and the benthic cyanobacterium Lyngbya majuscula had the highest uptake rates per unit biomass, whereas the coral Madracis mirabilis had the lowest. Combining nutrient uptake rates with the standing biomass of each functional group on the reef, we estimated that the ammonium and phosphate delivered during runoff events is mostly taken up by turf algae and the two macroalgae Lobophora variegata and Dictyota pulchella. Our results support the often proposed, but rarely tested, assumption that turf algae and opportunistic macroalgae primarily benefit from episodic inputs of nutrients to coral reefs.

Effect of temperature on rates of ammonium uptake and nitrification in the western coastal Arctic during winter, spring, and summer

NASA Astrophysics Data System (ADS)

Baer, Steven E.; Connelly, Tara L.; Sipler, Rachel E.; Yager, Patricia L.; Bronk, Deborah A.

2014-12-01

Biogeochemical rate processes in the Arctic are not currently well constrained, and there is very limited information on how rates may change as the region warms. Here we present data on the sensitivity of ammonium (NH4+) uptake and nitrification rates to short-term warming. Samples were collected from the Chukchi Sea off the coast of Barrow, Alaska, during winter, spring, and summer and incubated for 24 h in the dark with additions of 15NH4+ at -1.5, 6, 13, and 20°C. Rates of NH4+ uptake and nitrification were measured in conjunction with bacterial production. In all seasons, NH4+ uptake rates were highest at temperatures similar to current summertime conditions but dropped off with increased warming, indicative of psychrophilic (i.e., cold-loving) microbial communities. In contrast, nitrification rates were less sensitive to temperature and were higher in winter and spring compared to summer. These findings suggest that as the Arctic coastal ecosystem continues to warm, NH4+ assimilation may become increasingly important, relative to nitrification, although the magnitude of NH4+ assimilation would be still be lower than nitrification.

The Capacity for Thermal Protection of Photosynthetic Electron Transport Varies for Different Monoterpenes in Quercus ilex1

PubMed Central

Copolovici, Lucian O.; Filella, Iolanda; Llusià, Joan; Niinemets, Ülo; Peñuelas, Josep

2005-01-01

Heat stress resistance of foliar photosynthetic apparatus was investigated in the Mediterranean monoterpene-emitting evergreen sclerophyll species Quercus ilex. Leaf feeding with fosmidomycin, which is a specific inhibitor of the chloroplastic isoprenoid synthesis pathway, essentially stopped monoterpene emission and resulted in the decrease of the optimum temperature of photosynthetic electron transport from approximately 38°C to approximately 30°C. The heat stress resistance was partly restored by fumigation with 4 to 5 nmol mol−1 air concentrations of monoterpene α-pinene but not with fumigations with monoterpene alcohol α-terpineol. Analyses of monoterpene physicochemical characteristics demonstrated that α-pinene was primarily distributed to leaf gas and lipid phases, while α-terpineol was primarily distributed to leaf aqueous phase. Thus, for a common monoterpene uptake rate, α-terpineol is less efficient in stabilizing membrane liquid-crystalline structure and as an antioxidant in plant membranes. Furthermore, α-terpineol uptake rate (U) strongly decreased with increasing temperature, while the uptake rates of α-pinene increased with increasing temperature, providing a further explanation of the lower efficiency of thermal protection by α-terpineol. The temperature-dependent decrease of α-terpineol uptake was both due to decreases in stomatal conductance, gw, and increased volatility of α-terpineol at higher temperature that decreased the monoterpene diffusion gradient between the ambient air (FA) and leaf (FI; U = gw[FA − FI]). Model analyses suggested that α-pinene reacted within the leaf at higher temperatures, possibly within the lipid phase, thereby avoiding the decrease in diffusion gradient, FA − FI. Thus, these data contribute to the hypothesis of the antioxidative protection of leaf membranes during heat stress by monoterpenes. These data further suggest that fumigation with the relatively low atmospheric concentrations of monoterpenes that are occasionally observed during warm windless days in the Mediterranean canopies may significantly improve the heat tolerance of nonemitting vegetation that grows intermixed with emitting species. PMID:16126854

Cancer screening behaviours among South Asian immigrants in the UK, US and Canada: a scoping study.

PubMed

Crawford, Joanne; Ahmad, Farah; Beaton, Dorcas; Bierman, Arlene S

2016-03-01

South Asian (SA) immigrants settled in the United Kingdom (UK) and North America [United States (US) and Canada] have low screening rates for breast, cervical and colorectal cancers. Incidence rates of these cancers increase among SA immigrants after migration, becoming similar to rates in non-Asian native populations. However, there are disparities in cancer screening, with low cancer screening uptake in this population. We conducted a scoping study using Arksey & O'Malley's framework to examine cancer screening literature on SA immigrants residing in the UK, US and Canada. Eight electronic databases, key journals and reference lists were searched for English language studies and reports. Of 1465 identified references, 70 studies from 1994 to November 2014 were included: 63% on breast or cervical cancer screening or both; 10% examined colorectal cancer screening only; 16% explored health promotion/service provision; 8% studied breast, cervical and colorectal cancer screening; and 3% examined breast and colorectal cancer screening. A thematic analysis uncovered four dominant themes: (i) beliefs and attitudes towards cancer and screening included centrality of family, holistic healthcare, fatalism, screening as unnecessary and emotion-laden perceptions; (ii) lack of knowledge of cancer and screening related to not having heard about cancer and its causes, or lack of awareness of screening, its rationale and/or how to access services; (iii) barriers to access including individual and structural barriers; and (iv) gender differences in screening uptake and their associated factors. Findings offer insights that can be used to develop culturally sensitive interventions to minimise barriers and increase cancer screening uptake in these communities, while recognising the diversity within the SA culture. Further research is required to address the gap in colorectal cancer screening literature to more fully understand SA immigrants' perspectives, as well as research to better understand gender-specific factors that influence screening uptake. © 2015 John Wiley & Sons Ltd.

Soil and plant factors influencing the accumulation of heavy metals by plants.

PubMed Central

Cataldo, D A; Wildung, R E

1978-01-01

The use of plants to monitor heavy metal pollution in the terrestrial environment must be based on a cognizance of the complicated, integrated effects of pollutant source and soil-plant variables. To be detectable in plants, pollutant sources must significantly increase the plant available metal concentration in soil. The major factor governing metal availability to plants in soils is the solubility of the metal associated with the solid phase, since in order for root uptake to occur, a soluble species must exist adjacent to the root membrane for some finite period. The rate of release and form of this soluble species will have a strong influence on the rate and extent of uptake and, perhaps, mobility and toxicity in the plant and consuming animals. The factors influencing solubility and form of available metal species in soil vary widely geographically and include the concentration and chemical form of the element entering soil, soil properties (endogenous metal concentration, mineralogy, particle size distribution), and soil processes (e.g., mineral weathering, microbial activity), as these influence the kinetics of sorption reactions, metal concentration in solution and the form of soluble and insoluble chemical species. The plant root represents the first barrier to the selective accumulation of ions present in soil solution. Uptake and kinetic data for nutrient ions and chemically related nonnutrient analogs suggest that metabolic processes associated with root absorption of nutrients regulate both the affinity and rate of absorption of specific nonnutrient ions. Detailed kinetic studies of Ni, Cd, and Tl uptake by intact plants demonstrate multiphasic root absorption processes over a broad concentration range, and the use of transport mechanisms in place for the nutrient ions Cu, Zn, and K. Advantages and limitations of higher plants as indicators of increased levels of metal pollution are discussed in terms of these soil and plant phenomena. PMID:367766

The use of a mercury biosensor to evaluate the bioavailability of mercury-thiol complexes and mechanisms of mercury uptake in bacteria

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

Ndu, Udonna; Barkay, Tamar; Mason, Robert P.

We discuss as mercury (Hg) biosensors are sensitive to only intracellular Hg, they are useful in the investigation of Hg uptake mechanisms and the effects of speciation on Hg bioavailability to microbes. In this study, bacterial biosensors were used to evaluate the roles that several transporters such as the glutathione, cystine/cysteine, and Mer transporters play in the uptake of Hg from Hg-thiol complexes by comparing uptake rates in strains with functioning transport systems to strains where these transporters had been knocked out by deletion of key genes. The Hg uptake into the biosensors was quantified based on the intracellular conversionmore » of inorganic mercury (Hg(II)) to elemental mercury (Hg(0)) by the enzyme MerA. It was found that uptake of Hg from Hg-cysteine (Hg(CYS) 2) and Hg-glutathione (Hg(GSH) 2) complexes occurred at the same rate as that of inorganic complexes of Hg(II) into Escherichia coli strains with and without intact Mer transport systems. However, higher rates of Hg uptake were observed in the strain with a functioning Mer transport system. These results demonstrate that thiol-bound Hg is bioavailable to E. coli and that this bioavailability is higher in Hg-resistant bacteria with a complete Mer system than in non-resistant strains. No difference in the uptake rate of Hg from Hg(GSH) 2 was observed in E. coli strains with or without functioning glutathione transport systems. There was also no difference in uptake rates between a wildtype Bacillus subtilis strain with a functioning cystine/cysteine transport system, and a mutant strain where this transport system had been knocked out. These results cast doubt on the viability of the hypothesis that the entire Hg-thiol complex is taken up into the cell by a thiol transporter. It is more likely that the Hg in the Hg-thiol complex is transferred to a transport protein on the cell membrane and is subsequently internalized.« less

The use of a mercury biosensor to evaluate the bioavailability of mercury-thiol complexes and mechanisms of mercury uptake in bacteria

DOE PAGES

Ndu, Udonna; Barkay, Tamar; Mason, Robert P.; ...

2015-09-15

We discuss as mercury (Hg) biosensors are sensitive to only intracellular Hg, they are useful in the investigation of Hg uptake mechanisms and the effects of speciation on Hg bioavailability to microbes. In this study, bacterial biosensors were used to evaluate the roles that several transporters such as the glutathione, cystine/cysteine, and Mer transporters play in the uptake of Hg from Hg-thiol complexes by comparing uptake rates in strains with functioning transport systems to strains where these transporters had been knocked out by deletion of key genes. The Hg uptake into the biosensors was quantified based on the intracellular conversionmore » of inorganic mercury (Hg(II)) to elemental mercury (Hg(0)) by the enzyme MerA. It was found that uptake of Hg from Hg-cysteine (Hg(CYS) 2) and Hg-glutathione (Hg(GSH) 2) complexes occurred at the same rate as that of inorganic complexes of Hg(II) into Escherichia coli strains with and without intact Mer transport systems. However, higher rates of Hg uptake were observed in the strain with a functioning Mer transport system. These results demonstrate that thiol-bound Hg is bioavailable to E. coli and that this bioavailability is higher in Hg-resistant bacteria with a complete Mer system than in non-resistant strains. No difference in the uptake rate of Hg from Hg(GSH) 2 was observed in E. coli strains with or without functioning glutathione transport systems. There was also no difference in uptake rates between a wildtype Bacillus subtilis strain with a functioning cystine/cysteine transport system, and a mutant strain where this transport system had been knocked out. These results cast doubt on the viability of the hypothesis that the entire Hg-thiol complex is taken up into the cell by a thiol transporter. It is more likely that the Hg in the Hg-thiol complex is transferred to a transport protein on the cell membrane and is subsequently internalized.« less

Fatty acid transport protein-2 inhibitor Grassofermata/CB5 protects cells against lipid accumulation and toxicity

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

Saini, Nipun; Black, Paul N.; Montefusco, David

The inhibition of the fatty acid uptake into non-adipose tissues provides an attractive target for prevention of lipotoxicity leading to obesity-associated non-alcoholic fatty liver disease and type 2 diabetes. Fatty acid transport proteins (FATPs) are bifunctional proteins involved in the uptake and activation of fatty acids by esterification with coenzyme A. Here we characterize Grassofermata/CB5, previously identified as a fatty acid uptake inhibitor directed against HsFATP2. The compound was effective in inhibiting the uptake of fatty acids in the low micro-molar range (IC{sub 50} 8–11 μM) and prevented palmitate-mediated lipid accumulation and cell death in cell lines that are models formore » intestines, liver, muscle and pancreas. In adipocytes, uptake inhibition was less effective (IC{sub 50} 58 μM). Inhibition was specific for long chain fatty acids and was ineffective toward medium chain fatty acids, which are transported by diffusion. Kinetic analysis of Grassofermata-dependent FA transport inhibition verified a non-competitive mechanism. By comparison with Grassofermata, several atypical antipsychotic drugs previously implicated as inhibitors of FA uptake were ineffectual. In mice Grassofermata decreased absorption of {sup 13}C-oleate demonstrating its potential as a therapeutic agent. - Highlights: • Grassofermata is a small compound inhibitor of FATP2. • Uptake inhibition is specific for long chain fatty acids. • Uptake kinetics shows low specificity for adipocytes compared to other cell types. • Inhibition is by a non-competitive mechanism. • Atypical antipsychotics do not inhibit FA uptake by comparison with Grassofermata.« less

Factors Associated with HPV Vaccination among Cambodian American Teenagers.

PubMed

Lee, Haeok; Kim, Minjin; Kiang, Peter; Shi, Ling; Tan, Kevin; Chea, Phala; Peou, Sonith; Grigg-Saito, Dorcas C

2016-11-01

Parents have general influence over their children's health and health behavior. However, given the dearth of specific literature regarding knowledge level and social and cultural factors influencing HPV vaccination behaviors among Cambodian American (CA) parent, it is difficult to develop an effective, evidence-based public health HPV vaccination program. Therefore, the objectives of this study were to determine the HPV vaccine uptakes among CA teenagers and to examine factors influencing HPV vaccine uptakes. A descriptive, cross-sectional survey design and a combination of network and targeted sampling methods were used. CA mothers (n = 130) completed a health survey through face-to-face interviews in either English or Khmer language. Girls vaccination rates were 29% while that of boys was 16%. Awareness and knowledge of HPV among CA mothers was very low, and many believed that their daughters, who speak English and were educated in the U.S., had more knowledge about health than they did. Logistic regression analysis showed that CA girls had significantly higher odds of vaccination when their mothers possessed a higher level of English reading ability and had greater awareness and knowledge of HPV. The strikingly low rates of HPV vaccination among CA girls and boys underscore the need to improve vaccination outreach, education, and uptake. The findings can be used to develop targeted public health HPV vaccination programs for CAs, which will reduce cervical cancer disparities. © 2016 Wiley Periodicals, Inc.

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

Adult root structure of Mediterranean shrubs: relationship with post-fire regenerative syndrome.

PubMed

Saura-Mas, S; Lloret, F

2014-01-01

Life-history attributes can impose differences on root system structures and properties related to nutrient and water uptake. Here, we assess whether plants with different post-fire regenerative strategies (resprouters, seeders and seeder-resprouters) differ in the topological and morphological properties of their root systems (external path, altitude, magnitude, topological index, specific root length, root length, root-to-shoot biomass ratio, length of the main axis of the root system and link length). To achieve these objectives, we sampled individuals from eight woody species in a shrubland located in the western Mediterranean Basin. We sampled the adult root systems using manual field excavation with the aid of an air compressor. The results indicate that resprouters have a higher root-to-shoot ratio, confirming their higher ability to store water, starch and nutrients and to invest in the belowground biomass. Moreover, this pattern would allow them to explore deeper parts of the soil layers. Seeder species would benefit from a higher specific root length, pointing to increased relative root growth and water uptake rates. This study confirms that seeders and resprouters may differ in nutrient and water uptake ability according to the characteristics of their root system. Species that can both resprout and establish seedlings after fire had different patterns of root system structure; in particular, root:shoot ratio was more similar to resprouters and specific root length was closer to seeders, supporting the distinct functional performance of this type of species. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

Relative importance of plant uptake and plant associated denitrification for removal of nitrogen from mine drainage in sub-arctic wetlands.

PubMed

Hallin, Sara; Hellman, Maria; Choudhury, Maidul I; Ecke, Frauke

2015-11-15

Reactive nitrogen (N) species released from undetonated ammonium-nitrate based explosives used in mining or other blasting operations are an emerging environmental problem. Wetlands are frequently used to treat N-contaminated water in temperate climate, but knowledge on plant-microbial interactions and treatment potential in sub-arctic wetlands is limited. Here, we compare the relative importance of plant uptake and denitrification among five plant species commonly occurring in sub-arctic wetlands for removal of N in nitrate-rich mine drainage in northern Sweden. Nitrogen uptake and plant associated potential denitrification activity and genetic potential for denitrification based on quantitative PCR of the denitrification genes nirS, nirK, nosZI and nosZII were determined in plants growing both in situ and cultivated in a growth chamber. The growth chamber and in situ studies generated similar results, suggesting high relevance and applicability of results from growth chamber experiments. We identified denitrification as the dominating pathway for N-removal and abundances of denitrification genes were strong indicators of plant associated denitrification activity. The magnitude and direction of the effect differed among the plant species, with the aquatic moss Drepanocladus fluitans showing exceptionally high ratios between denitrification and uptake rates, compared to the other species. However, to acquire realistic estimates of N-removal potential of specific wetlands and their associated plant species, the total plant biomass needs to be considered. The species-specific plant N-uptake and abundance of denitrification genes on the root or plant surfaces were affected by the presence of other plant species, which show that both multi- and inter-trophic interactions are occurring. Future studies on N-removal potential of wetland plant species should consider how to best exploit these interactions in sub-arctic wetlands. Copyright © 2015 Elsevier Ltd. All rights reserved.

Glycyrrhetinic Acid Liposomes Containing Mannose-Diester Lauric Diacid-Cholesterol Conjugate Synthesized by Lipase-Catalytic Acylation for Liver-Specific Delivery.

PubMed

Chen, Jing; Chen, Yuchao; Cheng, Yi; Gao, Youheng

2017-09-24

Mannose-diester lauric diacid-cholesterol (Man-DLD-Chol), as a liposomal target ligand, was synthesized by lipase catalyzed in a non-aqueous medium. Its chemical structure was confirmed by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. Glycyrrhetinic acid (GA) liposomes containing Man-DLD-Chol (Man-DLD-Chol-GA-Lp) were prepared by the film-dispersion method. We evaluated the characterizations of liposomes, drug-release in vitro, the hemolytic test, cellular uptake, pharmacokinetics, and the tissue distributions. The cellular uptake in vitro suggested that the uptake of Man-DLD-Chol-modified liposomes was significantly higher than that of unmodified liposomes in HepG2 cells. Pharmacokinetic parameters indicated that Man-DLD-Chol-GA-Lp was eliminated more rapidly than GA-Lp. In tissue distributions, the targeting efficiency (Te) of Man-DLD-Chol-GA-Lp on liver was 54.67%, relative targeting efficiency (R Te ) was 3.39, relative uptake rate (Re) was 4.78, and peak concentration ratio (Ce) was 3.46. All these results supported the hypothesis that Man-DLD-Chol would be an efficient liposomal carrier, and demonstrated that Man-DLD-Chol-GA-Lp has potential as a drug delivery for liver-targeting therapy.

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

A conserved carboxylic acid group mediates light-dependent proton uptake and signaling by rhodopsin.

PubMed

Arnis, S; Fahmy, K; Hofmann, K P; Sakmar, T P

1994-09-30

A carboxylic acid residue is conserved at the cytoplasmic border of the third transmembrane segment among nearly all G protein-coupled receptors. In the visual receptor rhodopsin, replacement of the conserved Glu134 by a neutral glutamine results in enhanced transducin activation. Here we show that a key event in forming the active state of rhodopsin is proton uptake by Glu134 in the metarhodopsin II (MII) photoproduct. Site-directed mutants E134D and E134Q were studied by flash photolysis, where formation rates of their photoproducts and rates of pH change could be monitored simultaneously. Both mutants showed normal MII formation rates. However, E134D displayed a slowed rate of proton uptake and E134Q displayed a loss of light-induced uptake of two protons from the aqueous phase. Thus, Glu134 mediates light-dependent proton uptake by MII. We propose that receptor activation requires a light-induced conformational change that allows protonation of Glu134 and subsequent protonation of a second group. The strong conservation of Glu134 in G protein-coupled receptors implies a general requirement for a proton acceptor group at this position to allow light- or ligand-dependent receptor activation.

Skeletal muscle protein accretion rates and hindlimb growth are reduced in late gestation intrauterine growth-restricted fetal sheep.

PubMed

Rozance, Paul J; Zastoupil, Laura; Wesolowski, Stephanie R; Goldstrohm, David A; Strahan, Brittany; Cree-Green, Melanie; Sheffield-Moore, Melinda; Meschia, Giacomo; Hay, William W; Wilkening, Randall B; Brown, Laura D

2018-01-01

Adults who were affected by intrauterine growth restriction (IUGR) suffer from reductions in muscle mass, which may contribute to insulin resistance and the development of diabetes. We demonstrate slower hindlimb linear growth and muscle protein synthesis rates that match the reduced hindlimb blood flow and oxygen consumption rates in IUGR fetal sheep. These adaptations resulted in hindlimb blood flow rates in IUGR that were similar to control fetuses on a weight-specific basis. Net hindlimb glucose uptake and lactate output rates were similar between groups, whereas amino acid uptake was significantly lower in IUGR fetal sheep. Among all fetuses, blood O 2 saturation and plasma glucose, insulin and insulin-like growth factor-1 were positively associated and norepinephrine was negatively associated with hindlimb weight. These results further our understanding of the metabolic and hormonal adaptations to reduced oxygen and nutrient supply with placental insufficiency that develop to slow hindlimb growth and muscle protein accretion. Reduced skeletal muscle mass in the fetus with intrauterine growth restriction (IUGR) persists into adulthood and may contribute to increased metabolic disease risk. To determine how placental insufficiency with reduced oxygen and nutrient supply to the fetus affects hindlimb blood flow, substrate uptake and protein accretion rates in skeletal muscle, late gestation control (CON) (n = 8) and IUGR (n = 13) fetal sheep were catheterized with aortic and femoral catheters and a flow transducer around the external iliac artery. Muscle protein kinetic rates were measured using isotopic tracers. Hindlimb weight, linear growth rate, muscle protein accretion rate and fractional synthetic rate were lower in IUGR compared to CON (P < 0.05). Absolute hindlimb blood flow was reduced in IUGR (IUGR: 32.9 ± 5.6 ml min -1 ; CON: 60.9 ± 6.5 ml min -1 ; P < 0.005), although flow normalized to hindlimb weight was similar between groups. Hindlimb oxygen consumption rate was lower in IUGR (IUGR: 10.4 ± 1.4 μmol min -1  100 g -1 ; CON: 14.7 ± 1.3 μmol min -1  100 g -1 ; P < 0.05). Hindlimb glucose uptake and lactate output rates were similar between groups, whereas amino acid uptake was lower in IUGR (IUGR: 1.3 ± 0.5 μmol min -1  100 g -1 ; CON: 2.9 ± 0.2 μmol min -1  100 g -1 ; P < 0.05). Blood O 2 saturation (r 2  = 0.80, P < 0.0001) and plasma glucose (r 2  = 0.68, P < 0.0001), insulin (r 2  = 0.40, P < 0.005) and insulin-like growth factor (IGF)-1 (r 2  = 0.80, P < 0.0001) were positively associated and norepinephrine (r 2  = 0.59, P < 0.0001) was negatively associated with hindlimb weight. Slower hindlimb linear growth and muscle protein synthesis rates match reduced hindlimb blood flow and oxygen consumption rates in the IUGR fetus. Metabolic adaptations to slow hindlimb growth are probably hormonally-mediated by mechanisms that include increased fetal norepinephrine and reduced IGF-1 and insulin. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Season and application rates affect vaccine bait consumption by prairie dogs in Colorado and Utah, USA

USGS Publications Warehouse

Tripp, Daniel W.; Rocke, Tonie E.; Streich, Sean P.; Brown, Nathanael L.; Fernandez, Julia Rodriguez-Ramos; Miller, Michael W.

2014-01-01

Plague, a zoonotic disease caused by the bacterium Yersinia pestis, causes high rates of mortality in prairie dogs (Cynomys spp.). An oral vaccine against plague has been developed for prairie dogs along with a palatable bait to deliver vaccine and a biomarker to track bait consumption. We conducted field trials between September 2009 and September 2012 to develop recommendations for bait distribution to deliver plague vaccine to prairie dogs. The objectives were to evaluate the use of the biomarker, rhodamine B, in field settings to compare bait distribution strategies, to compare uptake of baits distributed at different densities, to assess seasonal effects on bait uptake, and to measure bait uptake by nontarget small mammal species. Rhodamine B effectively marked prairie dogs' whiskers during these field trials. To compare bait distribution strategies, we applied baits around active burrows or along transects at densities of 32, 65, and 130 baits/ha. Distributing baits at active burrows or by transect did not affect uptake by prairie dogs. Distributing baits at rates of ≥65/ha (or ≥1 bait/active burrow) produced optimal uptake, and bait uptake by prairie dogs in the autumn was superior to uptake in the spring. Six other species of small mammals consumed baits during these trials. All four species of tested prairie dogs readily consumed the baits, demonstrating that vaccine uptake will not be an obstacle to plague control via oral vaccination.

Calcium uptake in aquatic insects: influences of phylogeny and metals (Cd and Zn).

PubMed

Poteat, Monica D; Buchwalter, David B

2014-04-01

Calcium sequestration in the hypo-osmotic freshwater environment is imperative in maintaining calcium homeostasis in freshwater aquatic organisms. This uptake process is reported to have the unintended consequence of potentially toxic heavy metal (Cd, Zn) uptake in a variety of aquatic species. However, calcium uptake remains poorly understood in aquatic insects, the dominant invertebrate faunal group in most freshwater ecosystems. Here, we examined Ca uptake and interactions with heavy metals (Cd, Zn) at low ambient Ca levels (12.5 μmol l(-1)) in 12 aquatic insect species within Ephemerellidae (mayfly) and Hydropsychidae (caddisfly), two families differentially responsive to trace metal pollution. We found Ca uptake varied 70-fold across the 12 species studied. Body mass and clade (family) were found to significantly influence both Ca uptake and adsorption (P≤0.05). Zn and Cd uptake rate constants (ku) exhibited a strong correlation (r=0.96, P<0.0001), suggesting a shared transport system. Ca uptake failed to significantly correlate with either Zn or Cd ku values. Further, neither Zn nor Cd exhibited inhibitory effects toward Ca uptake. In fact, we saw evidence of modest stimulation of Ca uptake rates in some metal treatments. This work suggests that insects generally differ from other freshwater taxa in that aqueous Ca uptake does not appear to be compromised by Cd or Zn exposure. It is important to understand the trace metal and major ion physiology of aquatic insects because of their ecological importance and widespread use as ecological indicators.

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.

Effects of temperature, algae biomass and ambient nutrient on the absorption of dissolved nitrogen and phosphate by Rhodophyte Gracilaria asiatica

NASA Astrophysics Data System (ADS)

Du, Rongbin; Liu, Liming; Wang, Aimin; Wang, Yongqiang

2013-03-01

Gracilaria asiatica, being highly efficient in nutrient absorption, is cultivated in sea cucumber ponds to remove nutrients such as nitrogen and phosphate. It was cultured in a laboratory simulating field conditions, and its nutrient absorption was measured to evaluate effects of environmental conditions. Ammonia nitrogen (AN), nitrate nitrogen (NN), total inorganic nitrogen (TIN), and soluble reactive phosphorus (SRP) uptake rate and removal efficiency were determined in a 4×2 factorial design experiment in water temperatures ( T) at 15°C and 25°C, algae biomass (AB) at 0.5 g/L and 1.0 g/L, total inorganic nitrogen (TIN) at 30 μmol/L and 60 μmol/L, and soluble reactive phosphorus (SRP) at 3 and 6 μmol/L. AB and ambient TIN or SRP levels significantly affected uptake rate and removal efficiency of AN, NN, TIN, and SRP ( P< 0.001). G. asiatica in AB of 0.5 g/L showed higher uptake rate and lower removal efficiency relative to that with AB of 1.0 g/L. Nitrogen and phosphorus uptake rate rose with increasing ambient nutrient concentrations; nutrient removal efficiency decreased at higher environmental nutrient concentrations. The algae preferred to absorb AN to NN. Uptake rates of AN, NN, and SRP were significantly affected by temperature ( P < 0.001); uptake rate was higher for the 25°C group than for the 15°C group at the initial experiment stage. Only the removal efficiency of AN and SRP showed a significant difference between the two temperature groups ( P< 0.01). The four factors had significant interactive effects on absorption of N and P, implying that G. asiatica has great bioremedial potential in sea cucumber culture ponds.

Hierarchically porous organic polymers: highly enhanced gas uptake and transport through templated synthesis† †Electronic supplementary information (ESI) available: Complete procedures for the synthesis of hierarchically porous organic polymers and characterization data (gas adsorption–desorption isotherms, pore size distribution graphs, SEM images, and density data). Detailed procedures for propane uptake experiments and calculation of diffusion constants. See DOI: 10.1039/c4sc02502d Click here for additional data file.

PubMed Central

Chakraborty, Sanjiban; Colón, Yamil J.; Snurr, Randall Q.

2015-01-01

Porous organic polymers (POPs) possessing meso- and micropores can be obtained by carrying out the polymerization inside a mesoporous silica aerogel template and then removing the template after polymerization. The total pore volume (tpv) and specific surface area (ssa) can be greatly enhanced by modifying the template (up to 210% increase for tpv and 73% for ssa) as well as by supercritical processing of the POPs (up to an additional 142% increase for tpv and an additional 32% for ssa) to include larger mesopores. The broad range of pores allows for faster transport of molecules through the hierarchically porous POPs, resulting in increased diffusion rates and faster gas uptake compared to POPs with only micropores. PMID:28966764

Diflerent formulations of microbial respiratory losses and microbial efficiency have pronounced short and long term consequences for soil C dynamics and soil respiration

NASA Astrophysics Data System (ADS)

Ballantyne, F.; Billings, S. A.

2016-12-01

Much of the variability in projections of Earth's future C balance derives from uncertainty in how to formulate and parameterize models of biologically mediated transformations of soil organic C (SOC). Over the past decade, models of belowground decomposition have incorporated more realism, namely microbial biomass and exoenzyme pools, but it remains unclear whether microbially mediated decomposition is accurately formulated. Different models and different assumptions about how microbial efficiency, defined in terms of respiratory losses, varies with temperature exert great influence on SOC and CO2 flux projections for the future. Here, we incorporate a physiologically realistic formulation of CO2 loss from microbes, distinct from extant formulations and logically consistent with microbial C uptake and losses, into belowground dynamics and contrast its projections for SOC pools and CO2 flux from soils to those from the phenomenological formulations of efficiency in current models. We quantitatively describe how short and long term SOC dynamics are influenced by different mathematical formulations of efficiency, and that our lack of knowledge regarding loss rates from SOC and microbial biomass pools, specific respiration rate and maximum substrate uptake rate severely constrains our ability to confidently parameterize microbial SOC modules in Earth System Models. Both steady-state SOC and microbial biomass C pools, as well as transient responses to perturbations, can differ substantially depending on how microbial efficiency is derived. In particular, the discrepancy between SOC stocks for different formulations of efficiency varies from negligible to more than two orders of magnitude, depending on the relative values of respiratory versus non-respiratory losses from microbial biomass. Mass-specific respiration and proportional loss rates from soil microbes emerge as key determinants of the consequences of different formulations of efficiency for C flux in soils.

[Effects of Triton X-100 on the oxygen uptake rate of photosystem I particles treated at 70 degrees C].

PubMed

Chen, Wei; Yang, Zhen-Le; Li, Liang-Bi; Kuang, Ting-Yun

2005-06-01

The characteristics including oxygen uptake rates, fluorescence spectra and absorption spectra of photosystem I particles with or without Triton-X 100 treatment before or after the incubation at 70 degrees C for 10 min were compared. The oxygen uptake rates of photosystem I particles decreased after being incubated at 70 degrees C for 10 min, which could be recovered by the addition of Triton-X 100. Singlet oxygen was formed when the light-harvesting complex I was separated from the core complex of photosystem I, which resulted in high oxygen uptake rate. There was much difference in the fluorescence spectra of photosystem I particles between photosystem I particles treated with Triton-X 100 after the incubation at 70 degrees C for 10 min or not, which implies the ability of Triton-X 100 to promote the recovery of photosystem I particles after the incubation at 70 degrees C for 10 min.

Relation between the location of elements in the periodic table and various organ-uptake rates.

PubMed

Ando, A; Ando, I; Hiraki, T; Hisada, K

1989-01-01

Fifty four elements and 65 radioactive compounds were examined to determine the organ uptake rates for rats 3, 24 and 48 h after i.v. injection of these compounds. They were prepared as carrier free nuclides, or containing a small amount of stable nuclide. Generally speaking, behaviors of K, Rb, Cs and Tl in all the organs were very similar to one another, but they differed from that of Na. Bivalent hard acids were avidly taken up into bone; therefore, uptake rates in soft tissues were very small. Hard acids of tri-, quadri- and pentavalence which were taken up into the soft tissue organs decreased more slowly from these organs than other ions. Soft acids such as Hg2+ were bound very firmly to the component in the kidney. Anions (with few exceptions), GeCl4 and SbCl3 were rapidly excreted in urine, so that the uptake rates in organs were low.

Effect of the amino acid histidine on the uptake of cadmium from the digestive system of the blue crab, Callinectes sapidus

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

Pecon, J.; Powell, E.N.

1981-07-01

The digestive tract functions in the storage, metabolism, and excretion of heavy metals in invertebrates. The importance of the digestive tract and the processes governing digestion and absorption of nutrients in heavy metal uptake is becoming increasingly clear. The results of this study suggest that in order to understand the processes controlling heavy metal uptake in invertebrates, it will be necessary to investigate the role that digestion and absorption play in determining the transport rate of metals across the gut wall into the blood. For example, some amino acids increase metal absorption rates, whereas other compounds, such as phytate, decreasemore » metal absorption rates. The results also suggest that experimental designs to investigate metal absorption must include an appreciation of the significant role that the feeding state of the animal (e.g. fed or starved) and the role chelators, particularly those produced by the organisms themselves during digestion, may play in the observed uptake rates of metal ions.« less

Mass media effect on vaccines uptake during silent polio outbreak.

PubMed

Sagy, Iftach; Novack, Victor; Gdalevich, Michael; Greenberg, Dan

2018-03-14

During 2013, isolation of a wild type 1 poliovirus from routine sewage sample in Israel, led to a national OPV campaign. During this period, there was a constant cover of the outbreak by the mass media. To investigate the association of media exposure and OPV and non-OPV vaccines uptake during the 2013 silent polio outbreak in Israel. We received data on daily immunization rates during the outbreak period from the Ministry of Health (MoH). We conducted a multivariable time trend analysis to assess the association between daily media exposure and vaccines uptake. Analysis was stratified by ethnicity and socio-economic status (SES). During the MoH supplemental immunization activity, 138,799 OPV vaccines were given. There was a significant association between media exposure and OPV uptake, most prominent in a lag of 3-5 days from the exposure among Jews (R.R 1.79C.I 95% 1.32-2.41) and high SES subgroups (R.R 1.71C.I 95% 1.27-2.30). These subgroups also showed increased non-OPV uptake in a lag of 3-5 days from the media exposure, in all vaccines except for MMR. Lower SES and non-Jewish subgroups did not demonstrate the same association. Our findings expand the understanding of public behaviour during outbreaks. The public response shows high variability within specific subgroups. These findings highlight the importance of tailored communication strategies for each subgroup. Copyright © 2018 Elsevier Ltd. All rights reserved.

Relationship between volition, physical activity and weight loss maintenance: Study rationale, design, methods and baseline characteristics.

PubMed

Dandanell, Sune; Elbe, Anne-Marie; Pfister, Gertrud; Elsborg, Peter; W Helge, Jørn

2017-05-01

To investigate the relationship between volition, physical activity and weight loss maintenance. We recruited 84 sedentary (maximal oxygen uptake: 25 ± 5 ml/min), overweight and obese (Body mass index (BMI) 38 ± 7 m/h 2 , fat 44 ± 7 %) women ( n = 55) and men ( n = 29) for an interdisciplinary prospective study with follow-up. The change in lifestyle and weight loss is promoted via a 3-month intensive lifestyle intervention at a private health school. The intervention consists of supervised training (1-3 hours/day), a healthy hypo-caloric diet (-500 to -700 kCal/day) and education in healthy lifestyle in classes/groups. The participants' body weight and composition (Dual Energy X-ray absorptiometry), volitional skills (questionnaire), physical activity level (heart rate accelerometer/questionnaire) and maximal oxygen uptake (indirect calorimetry) are to be monitored before, after, and 3 and 12 months after the intervention. At the 12-month follow-up, three different groups will be established: Clinical weight loss maintenance (> 10% weight loss from baseline), moderate weight loss maintenance (1-10% weight loss) and no weight loss (or weight regain). A linear mixed model analysis will be used to compare levels of volitional skills, physical activity and maximal oxygen uptake over time, between the three groups. Correlational analyses will be used to investigate possible associations between volition, maximal oxygen uptake, physical activity level and weight loss maintenance. If specific volitional skills are identified as predictors of adherence to physical activity and success in clinical weight loss maintenance, these can be trained in future intensive lifestyle interventions in order to optimize the success rate.

Water flow and solute transport in the soil-plant-atmosphere continuum: Upscaling from rhizosphere to root zone

NASA Astrophysics Data System (ADS)

Lazarovitch, Naftali; Perelman, Adi; Guerra, Helena; Vanderborght, Jan; Pohlmeier, Andreas

2016-04-01

Root water and nutrient uptake are among the most important processes considered in numerical models simulating water content and fluxes in the subsurface, as they control plant growth and production as well as water flow and nutrient transport out of the root zone. Root water uptake may lead to salt accumulation at the root-soil interface, resulting in rhizophere salt concentrations much higher than in the bulk soil. This salt accumulation is caused by soluble salt transport towards the roots by mass flow through the soil, followed by preferential adsorption of specific nutrients by active uptake, thereby excluding most other salts at the root-soil interface or in the root apoplast. The salinity buildup can lead to large osmotic pressure gradients across the roots thereby effectively reducing root water uptake. The initial results from rhizoslides (capillary paper growth system) show that sodium concentration is decreasing with distance from the root, compared with the bulk that remained more stable. When transpiration rate was decreased under high salinity levels, sodium concentration was more homogenous compared with low salinity levels. Additionally, sodium and gadolinium distributions were measured nondestructively around tomato roots using magnetic resonance imaging (MRI). This technique could also observe the root structure and water content around single roots. Results from the MRI confirm the solutes concentration pattern around roots and its relation to their initial concentration. We conclude that local water potentials at the soil-root interface differ from bulk potentials. These relative differences increase with decreasing root density, decreasing initial salt concentration and increasing transpiration rate. Furthermore, since climate may significantly influence plant response to salinity a dynamic climate-coupled salinity reduction functions are critical in while using macroscopic numerical models.

Renal uptake and tolerability of a 2'-O-methoxyethyl modified antisense oligonucleotide (ISIS 113715) in monkey.

PubMed

Henry, Scott P; Johnson, Mark; Zanardi, Thomas A; Fey, Robert; Auyeung, Diana; Lappin, Patrick B; Levin, Arthur A

2012-11-15

The primary target organ for uptake of systemically administered phosphorothioate oligonucleotides is the kidney cortex and the proximal tubular epithelium in particular. To determine the effect of oligonucleotide uptake on renal function, a detailed renal physiology study was performed in cynomolgus monkeys treated with 10-40 mg/kg/week ISIS 113715 for 4 weeks. The concentrations of oligonucleotide in the kidney cortex ranged from 1400 to 2600 μg/g. These concentrations were associated with histologic changes in proximal tubular epithelial cells that ranged from the appearance of cytoplasmic basophilic granules to atrophic and degenerative changes at higher concentrations. However, there were no renal functional abnormalities as determined by the typical measurements of blood urea nitrogen, serum creatinine, creatinine clearance, or urine specific gravity. Nor were there changes in glomerular filtration rate, or renal blood flow. Specific urinary markers of tubular epithelial cell damage, such as N-acetyl-glucosaminidase, and α-glutathione-s-transferase were not affected. Tubular function was further evaluated by monitoring the urinary excretion of amino acids, β(2)-microglobulin, or glucose. Renal function was challenged by administering a glucose load and by examining concentrating ability after a 4-h water deprivation. Neither challenge produced any evidence of change in renal function. The only change observed was a low incidence of increased urine protein/creatinine ratio in monkeys treated with ≥40 mg/kg/week which was rapidly reversible. Collectively, these data indicate that ISIS 113715-uptake by the proximal tubular epithelium has little or no effect on renal function at concentrations of 2600 μg/g. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Effect of raw humus under two adult Scots pine stands on ectomycorrhization, nutritional status, nitrogen uptake, phosphorus uptake and growth of Pinus sylvestris seedlings.

PubMed

Schulz, Horst; Schäfer, Tina; Storbeck, Veronika; Härtling, Sigrid; Rudloff, Renate; Köck, Margret; Buscot, François

2012-01-01

Ectomycorrhiza (EM) formation improves tree growth and nutrient acquisition, particularly that of nitrogen (N). Few studies have coupled the effects of naturally occurring EM morphotypes to the nutrition of host trees. To investigate this, pine seedlings were grown on raw humus substrates collected at two forest sites, R2 and R3. Ectomycorrhiza morphotypes were identified, and their respective N uptake rates from organic (2-(13)C, (15)N-glycine) and inorganic ((15)NH(4)Cl, Na(15)NO(3), (15)NH(4)NO(3), NH(4)(15)NO(3)) sources as well as their phosphate uptake rates were determined. Subsequently, the growth and nutritional status of the seedlings were analyzed. Two dominant EM morphotypes displayed significantly different mycorrhization rates in the two substrates. Rhizopogon luteolus Fr. (RL) was dominant in R2 and Suillus bovinus (Pers.) Kuntze (SB) was dominant in R3. (15)N uptake of RL EM was at all times higher than that of SB EM. Phosphate uptake rates by the EM morphotypes did not differ significantly. The number of RL EM correlated negatively and the number of SB EM correlated positively with pine growth rate. Increased arginine concentrations and critical P/N ratios in needles indicated nutrient imbalances of pine seedlings from humus R2, predominantly mycorrhizal with RL. We conclude that different N supply in raw humus under Scots pine stands can induce shifts in the EM frequency of pine seedlings, and this may lead to EM formation by fungal strains with different ability to support tree growth.

The Role of Transporters in the Toxicity of Nucleoside and Nucleotide Analogs

PubMed Central

Koczor, Christopher A; Torres, Rebecca A

2013-01-01

Introduction Two families of nucleoside analogs have been developed to treat viral infections and cancer, but these compounds can cause tissue and cell-specific toxicity related to their uptake and subcellular activity which are dictated by host enzymes and transporters. Cellular uptake of these compounds requires nucleoside transporters that share functional similarities but differ in substrate specificity. Tissue-specific cellular expression of these transporters enables nucleoside analogs to produce their tissue specific toxic effects, a limiting factor in the treatment of retroviruses and cancer. Areas Covered This review discusses the families of nucleoside transporters and how they mediate cellular uptake of nucleoside analogs. Specific focus is placed on examples of known cases of transporter-mediated cellular toxicity and classification of the toxicities resulting. Efflux transporters are also explored as a contributor to analog toxicity and cell-specific effects. Expert Opinion Efforts to modulate transporter uptake/clearance remain long-term goals of oncologists and virologists. Accordingly, subcellular approaches that either increase or decrease intracellular nucleoside analog concentrations are eagerly sought and include transporter inhibitors and targeting transporter expression. However, additional understanding of nucleoside transporter kinetics, tissue expression, and genetic polymorphisms are required to design better molecules and better therapies. PMID:22509856

Modification of meta-iodobenzylguanidine uptake in neuroblastoma cells by elevated temperature.

PubMed Central

Armour, A.; Mairs, R. J.; Gaze, M. N.; Wheldon, T. E.

1994-01-01

Successful imaging or treatment of neuroblastoma with 131I-meta-iodobenzylguanidine (131I-mIBG) depends on the selectivity of active (type 1) uptake of mIBG in neuroblastoma cells relative to passive (type 2) uptake present in most normal tissues. This study investigates the effects of moderately elevated temperature (39-41 degrees C) on the cellular uptake of 131I-mIBG in two neuroblastoma cell lines [SK-N-BE(2c) and IMR-32] and in a non-neuronal (ovarian carcinoma) cell line (A2780). In SK-N-BE(2c), a cell line with high active uptake capacity, the specific (type 1) uptake was reduced by 75% (P < 0.001) at 39 degrees C. Both IMR-32 and A2780 have a low capacity for accumulation of mIBG by active uptake. These cell lines demonstrated a statistically significant increase in accumulation at 39 degrees C, mainly as a result of increased non-specific transport. At 41 degrees C uptake of 131I-mIBG was reduced in all cell lines. Thus, the active component of mIBG uptake is more vulnerable to increased temperature than the passive component. It seems probable that moderately increased temperature will have an unfavourable effect on the therapeutic differential for targeted radiotherapy of neuroblastoma using radiolabelled mIBG. PMID:8080728

MO-FG-BRA-05: Dosimetric and Radiobiological Validation of Respiratory Gating in Conventional and Hypofractionated Radiotherapy of the Lung: Effect of Dose, Dose Rate, Gating Window and Breathing Pattern

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

Cervino, L; Soultan, D; Pettersson, N

2016-06-15

Purpose: to evaluate the dosimetric and radiobiological consequences from having different gating windows, dose rates, and breathing patterns in gated VMAT lung radiotherapy. Methods: A novel 3D-printed moving phantom with central high and peripheral low tracer uptake regions was 4D FDG-PET/CT-scanned using ideal, patient-specific regular, and irregular breathing patterns. A scan of the stationary phantom was obtained as a reference. Target volumes corresponding to different uptake regions were delineated. Simultaneous integrated boost (SIB) 6 MV VMAT plans were produced for conventional and hypofractionated radiotherapy, using 30–70 and 100% cycle gating scenarios. Prescribed doses were 200 cGy with SIB to 240more » cGy to high uptake volume for conventional, and 800 with SIB to 900 cGy for hypofractionated plans. Dose rates of 600 MU/min (conventional and hypofractionated) and flattening filter free 1400 MU/min (hypofractionated) were used. Ion chamber measurements were performed to verify delivered doses. Vials with A549 cells placed in locations matching ion chamber measurements were irradiated using the same plans to measure clonogenic survival. Differences in survival for the different doses, dose rates, gating windows, and breathing patterns were analyzed. Results: Ion chamber measurements agreed within 3% of the planned dose, for all locations, breathing patterns and gating windows. Cell survival depended on dose alone, and not on gating window, breathing pattern, MU rate, or delivery time. The surviving fraction varied from approximately 40% at 2Gy to 1% for 9 Gy and was within statistical uncertainty relative to that observed for the stationary phantom. Conclusions: Use of gated VMAT in PET-driven SIB radiotherapy was validated using ion chamber measurements and cell survival assays for conventional and hypofractionated radiotherapy.« less

Size-related and seasonal diet of the manila clam (Ruditapes philippinarum), as determined using dual stable isotopes

NASA Astrophysics Data System (ADS)

Suh, Yeon Jee; Shin, Kyung-Hoon

2013-12-01

Stable isotope ratios of lab-cultured Manila clams (Ruditapes philippinarum) and those from natural tidal flats of Seonjae Island in Korea were investigated in terms of their dietary uptake patterns in relation to body size and season. The smallest size group of wild Manila clams revealed significantly depleted δ15N based on the results of a one-way ANOVA. There was significant seasonal change in the proportional contribution of food sources, especially in winter, from benthic particulate organic matter (BPOM) to pelagic particulate organic matter (POM). Laboratory-cultured Manila clams showed growth rates of 6.02-37.75 mm/yr, and smaller-sized clams did not fully utilise the microalgal diets that were provided constantly. Instead, they derived most of their energy from detritus or dead microalgae that had settled on the bottom. Bigger clams, however, exhibited well-balanced source contributions, converting the microalgal diets into biomass. This demonstrates intra-specific differences in the growth rates and preferred diet uptakes of Manila clams, even under similar environmental conditions.

Functional analysis of apf1 mutation causing defective amino acid transport in Saccharomyces cerevisiae.

PubMed

Horák, J; Kotyk, A

1993-04-01

Mutation in the Apf1 locus causes a pleiotropic effect of H(+)-driven active amino acid transport in baker's yeast Saccharomyces cerevisiae. The uptake of other, presumably H(+)-driven, substances, e.g. of purine and pyrimidine bases, maltose and phosphate ions, is not significantly influenced by this mutation. The apf1 mutation decreases not only the initial rates of amino acid uptake but also the accumulation ratios of amino acids taken up but has virtually no effect on the membrane potential or on the delta pH which constitute the thermodynamically relevant source of energy for their transport. Similarly, no changes in intracellular ATP content, in ATP-hydrolyzing and H(+)-extruding H(+)-ATPase activities, in the efflux of intracellularly accumulated amino acids, or in rates of endogenous respiration, were observed in the apf1 mutant phenotype. Hence, all these data are in accordance with the experiments showing that the Apf1 protein, an integral protein of the endoplasmic reticulum, is required exclusively for efficient processing and translocation of transport proteins specific for amino acids from the endoplasmic reticulum to their final destination, the plasma membrane.

Real‐time monitoring of specific oxygen uptake rates of embryonic stem cells in a microfluidic cell culture device

PubMed Central

Super, Alexandre; Jaccard, Nicolas; Cardoso Marques, Marco Paulo; Macown, Rhys Jarred; Griffin, Lewis Donald; Veraitch, Farlan Singh

2016-01-01

Abstract Oxygen plays a key role in stem cell biology as a signaling molecule and as an indicator of cell energy metabolism. Quantification of cellular oxygen kinetics, i.e. the determination of specific oxygen uptake rates (sOURs), is routinely used to understand metabolic shifts. However current methods to determine sOUR in adherent cell cultures rely on cell sampling, which impacts on cellular phenotype. We present real‐time monitoring of cell growth from phase contrast microscopy images, and of respiration using optical sensors for dissolved oxygen. Time‐course data for bulk and peri‐cellular oxygen concentrations obtained for Chinese hamster ovary (CHO) and mouse embryonic stem cell (mESCs) cultures successfully demonstrated this non‐invasive and label‐free approach. Additionally, we confirmed non‐invasive detection of cellular responses to rapidly changing culture conditions by exposing the cells to mitochondrial inhibiting and uncoupling agents. For the CHO and mESCs, sOUR values between 8 and 60 amol cell−1 s−1, and 5 and 35 amol cell−1 s−1 were obtained, respectively. These values compare favorably with literature data. The capability to monitor oxygen tensions, cell growth, and sOUR, of adherent stem cell cultures, non‐invasively and in real time, will be of significant benefit for future studies in stem cell biology and stem cell‐based therapies. PMID:27214658

A quality improvement initiative to increase HPV vaccine rates using an educational and reminder strategy with parents of preteen girls.

PubMed

Cassidy, Brenda; Braxter, Betty; Charron-Prochownik, Denise; Schlenk, Elizabeth A

2014-01-01

A quality improvement project was undertaken to determine if an evidence-based educational brochure and reminder system can increase human papillomavirus (HPV) vaccine uptake and dose completion rates. Development of a brochure to promote HPV vaccine uptake was based on predictors of parental acceptance and Health Belief Model concepts. Electronic alerts prompted telephone reminders for dose completion. This quality improvement project utilized a quasi-experimental design with 24 parents of preteen girls from a private pediatric practice and a historical control group of 29 parents. HPV vaccine rates were compared between the groups. A significant difference in HPV vaccine uptake (χ(2) = 11.668, P = .001; odds ratio [OR] = 9.429, 95% confidence interval [CI] = 2.686-33.101) and dose completion (χ(2) = 16.171, P < .001; OR = 22.500, 95% CI = 4.291-117.990) rates were found between the historical control and intervention groups. Parents who received the clinical protocol were 9.4 times and 22.5 times more likely to have HPV vaccine uptake and dose completion, respectively. Low national HPV vaccine rates demonstrate the need for theory-based vaccine delivery programs. These results show that an evidence-based educational brochure and reminder system appeared to improve HPV vaccine uptake and dose completion rates at this private pediatric practice. Copyright © 2014 National Association of Pediatric Nurse Practitioners. Published by Mosby, Inc. All rights reserved.

Kalman filter based glucose control at small set points during fed-batch cultivation of Saccharomyces cerevisiae.

PubMed

Arndt, Michael; Hitzmann, Bernd

2004-01-01

A glucose control system is presented, which is able to control cultivations of Saccharomyces cerevisiae even at low glucose concentrations. Glucose concentrations are determined using a special flow injection analysis (FIA) system, which does not require a sampling module. An extended Kalman filter is employed for smoothing the glucose measurements as well as for the prediction of glucose and biomass concentration, the maximum specific growth rate, and the volume of the culture broth. The predicted values are utilized for feedforward/feedback control of the glucose concentration at set points of 0.08 and 0.05 g/L. The controller established well-defined conditions over several hours up to biomass concentrations of 13.5 and 20.7 g/L, respectively. The specific glucose uptake rates at both set points were 1.04 and 0.68 g/g/h, respectively. It is demonstrated that during fed-batch cultivation an overall pure oxidative metabolism of glucose is maintained at the lower set point and a specific ethanol production rate of 0.18 g/g/h at the higher set point.

Effects of nitrogen and phosphorus additions on soil methane uptake in disturbed forests

NASA Astrophysics Data System (ADS)

Zheng, Mianhai; Zhang, Tao; Liu, Lei; Zhang, Wei; Lu, Xiankai; Mo, Jiangming

2016-12-01

Atmospheric nitrogen (N) deposition is generally thought to suppress soil methane (CH4) uptake in natural forests, and phosphorus (P) input may alleviate this negative effect. However, it remains unclear how N and P inputs control soil CH4 uptake in disturbed forests. In this study, soil CH4 uptake rates were measured in two disturbed forests, including a secondary forest (with previous, but not recent, disturbance) and a plantation forest (with recent continuous disturbance), in southern China for 34 months of N and/or P additions: control, N addition (150 kg N ha-1 yr-1), P addition (150 kg P ha-1 yr-1), and NP addition (150 kg N ha-1 yr-1 plus 150 kg P ha-1 yr-1). Mean CH4 uptake rate in control plots was significantly higher in the secondary forest (24.40 ± 0.81 µg CH4-C m-2 h-1) than in the plantation forest (17.07 ± 0.70 µg CH4-C m-2 h-1). CH4 uptake rate had negative relationships with soil water-filled pore space in both forests. In the secondary forest, N, P, and NP additions significantly decreased CH4 uptake by 39.7%, 27.8%, and 37.6%, respectively, but had no significant effects in the plantation forest, indicating that P input does not alleviate the suppression of CH4 uptake by N deposition. Taken together, our findings suggest that reducing anthropogenic disturbance, including harvesting of forest floor, and anthropogenic N and P inputs will increase soil CH4 uptake in disturbed forests, which is important in view of the increased trends in global warming during recent decades.

Hydrologic and geochemical effects on oxygen uptake in bottom sediments of an effluent-dominated river

USGS Publications Warehouse

McMahon, P.B.; Tindall, J.A.; Collins, J.A.; Lull, K.J.; Nuttle, J.R.

1995-01-01

More than 95% of the water in the South Platte River downstream from the largest wastewater treatment plant serving the metropolitan Denver, Colorado, area consists of treated effluent during some periods of low flow. Fluctuations in effluent-discharge rates caused daily changes in river stage that promoted exchange of water between the river and bottom sediments. Groundwater discharge measurements indicated fluxes of water across the sediment-water interface as high as 18 m3 s−1 km−1. Laboratory experiments indicated that downward movement of surface water through bottom sediments at velocities comparable to those measured in the field (median rate ≈0.005 cm s−1) substantially increased dissolved oxygen uptake rates in bottom sediments (maximum rate 212 ± 10 μmol O2 L−1 h−1) compared with rates obtained when no vertical advective flux was generated (maximum rate 25 ± 8.8 μmol O2 L−1 h−1). Additions of dissolved ammonium to surface waters generally increased dissolved oxygen uptake rates relative to rates measured in experiments without ammonium. However, the magnitude of the advective flux through bottom sediments had a greater effect on dissolved oxygen uptake rates than did the availability of ammonium. Results from this study indicated that efforts to improve dissolved oxygen dynamics in effluent-dominated rivers might include stabilizing daily fluctuations in river stage.

Evaluation of software sensors for on-line estimation of culture conditions in an Escherichia coli cultivation expressing a recombinant protein.

PubMed

Warth, Benedikt; Rajkai, György; Mandenius, Carl-Fredrik

2010-05-03

Software sensors for monitoring and on-line estimation of critical bioprocess variables have mainly been used with standard bioreactor sensors, such as electrodes and gas analyzers, where algorithms in the software model have generated the desired state variables. In this article we propose that other on-line instruments, such as NIR probes and on-line HPLC, should be used to make more reliable and flexible software sensors. Five software sensor architectures were compared and evaluated: (1) biomass concentration from an on-line NIR probe, (2) biomass concentration from titrant addition, (3) specific growth rate from titrant addition, (4) specific growth rate from the NIR probe, and (5) specific substrate uptake rate and by-product rate from on-line HPLC and NIR probe signals. The software sensors were demonstrated on an Escherichia coli cultivation expressing a recombinant protein, green fluorescent protein (GFP), but the results could be extrapolated to other production organisms and product proteins. We conclude that well-maintained on-line instrumentation (hardware sensors) can increase the potential of software sensors. This would also strongly support the intentions with process analytical technology and quality-by-design concepts. 2010 Elsevier B.V. All rights reserved.

Improving pneumococcal and herpes zoster vaccination uptake: expanding pharmacist privileges.

PubMed

Taitel, Michael S; Fensterheim, Leonard E; Cannon, Adam E; Cohen, Edward S

2013-09-01

To investigate how state-authorized pharmacist immunization privileges influence pharmacist intervention effectiveness in delivering pneumococcal and herpes zoster vaccinations and assess the implications these privileges have on vaccination rates. Cross-sectional study of Walgreens vaccination records from August 2011 to March 2012. A random sample of patients having a claim for influenza vaccination in the study period was selected. Vaccination uptake rates for pneumococcal disease and herpes zoster were calculated for previously unvaccinated patients at high risk for these conditions. Rates were examined by state-level pharmacist privileges. For states authorizing immunization by protocol or prescriptive authority, the 1-year pneumococcal vaccination uptake rate for previously unvaccinated, high-risk persons was 6.6%, compared with 2.5% for states requiring a prescription (P <.0001), and 2.8% for states with no authorization (P <.0001). For herpes zoster, the 1-year vaccination uptake rate was 3.3% for states authorizing per protocol/prescriptive authority, compared with 2.8% (not significant, P <.05) for states authorizing by prescription, and 1.0% for states with no authorization (P <.0001). A 148% increase of pneumococcal vaccination and a 77% increase of herpes zoster vaccination would result if all states granted pharmacists full immunization privileges. This analysis demonstrates that states that offer pharmacists full immunization privileges have higher vaccination uptake rates than states with restricted or no authorization. Considering the suboptimal vaccination rates of pneumonia and shingles and the public health goals of 2020, states with limited or no immunization authorization for pharmacists should consider expanding pharmacist privileges for these vaccinations.

Glucose uptake and glycolytic flux in adipose tissue from rats adapted to a high-protein, carbohydrate-free diet.

PubMed

Brito, S R; Moura, M A; Kawashita, N H; Brito, M N; Kettelhut, I C; Migliorini, R H

2001-10-01

Rates of glucose uptake by epididymal and retroperitoneal adipose tissue in vivo, as well as rates of hexose uptake and glycolytic flux in isolated adipocytes, were determined in rats adapted to a high-protein, carbohydrate-free (HP) diet and in control rats fed a balanced (N) diet. Adaptation to the HP diet induced a significant reduction in rates of glucose uptake, estimated with 2-deoxy-[1-(3)H]-glucose, both by adipose tissue (epididymal and retroperitoneal) in vivo and by isolated adipocytes. Twelve hours after replacement of the HP diet with the balanced diet, rates of adipose tissue uptake in vivo in HP-adapted rats returned to levels that did not differ significantly from those in N-fed rats. The rate of flux in the glycolytic pathway, estimated with (3)H[5]-glucose, was also significantly reduced in adipocytes from HP-fed rats. In agreement with the above findings, the activities of hexokinase (HK), phosphofructo-1-kinase (PFK-1), and pyruvate kinase (PK) were markedly reduced in adipose tissue from HP-adapted rats. The activity of pyruvate kinase was partially reverted by diet replacement for 12 hours. The low-plasma insulin and high-glucagon levels in HP-fed rats may have played an important role in the reduction of adipose tissue glucose utilization in these animals. Copyright 2001 by W.B. Saunders Company

Point-particle method to compute diffusion-limited cellular uptake.

PubMed

Sozza, A; Piazza, F; Cencini, M; De Lillo, F; Boffetta, G

2018-02-01

We present an efficient point-particle approach to simulate reaction-diffusion processes of spherical absorbing particles in the diffusion-limited regime, as simple models of cellular uptake. The exact solution for a single absorber is used to calibrate the method, linking the numerical parameters to the physical particle radius and uptake rate. We study the configurations of multiple absorbers of increasing complexity to examine the performance of the method by comparing our simulations with available exact analytical or numerical results. We demonstrate the potential of the method to resolve the complex diffusive interactions, here quantified by the Sherwood number, measuring the uptake rate in terms of that of isolated absorbers. We implement the method in a pseudospectral solver that can be generalized to include fluid motion and fluid-particle interactions. As a test case of the presence of a flow, we consider the uptake rate by a particle in a linear shear flow. Overall, our method represents a powerful and flexible computational tool that can be employed to investigate many complex situations in biology, chemistry, and related sciences.

Levels and determinants of breast and cervical cancer screening uptake in HIV-infected women compared with the general population in France.

PubMed

Tron, L; Lert, F; Spire, B; Dray-Spira, R

2017-03-01

Cancer is a growing concern for HIV-infected people, and screening plays a major role in alleviating the burden it causes. We sought to investigate the levels and determinants of breast cancer screening (BCS) and cervical cancer screening (CCS) in HIV-infected women as compared with the general population. The Agence Nationale de Recherche sur le Sida et les Hépatites Virales (ANRS)-Vespa2 study was conducted in 2011 in a national representative sample of 3022 HIV-infected hospital out-patients in France. The rates and correlates of BCS and CCS among HIV-infected women were compared with those in the general population using multivariate Poisson regression models. The BCS rate during the 2 years preceding the survey interview was 80.7% among HIV-infected women vs. 89.1% in the general population (P = 0.146). The CCS rate during the preceding 3 years was 88.1% among HIV-infected women vs. 83.1% in the general population (P = 0.021). During the preceding year, the CCS rate among HIV-infected women was 76.5%. The barriers to BCS and CCS were a low educational level [BCS: adjusted prevalence rate ratio 0.88; 95% confidence interval (CI) 0.80-0.97; CCS: adjusted prevalence rate ratio 0.91; 95% CI 0.83-0.99], not having supplementary health insurance (CCS: adjusted prevalence rate ratio 0.92; 95% CI 0.86-0.98), an irregular gynaecological follow-up (BCS: adjusted prevalence rate ratio 0.77; 95% CI 0.64-0.92; CCS: adjusted prevalence rate ratio 0.72; 95% CI 0.64-0.81) and a low CD4 count (BCS: adjusted prevalence rate ratio 0.83; 95% CI 0.71-0.97; CCS: adjusted prevalence rate ratio 0.78; 95% CI 0.63-0.98). The disparities in CCS uptake in terms of age, employment and gynaecological follow-up were less pronounced among HIV-infected women than in the general population. BCS and CCS uptake was not lower among HIV-infected women than in the general population, but CCS was suboptimal. Specificities in the profile of barriers to screening emerged. © 2016 British HIV Association.

Measurements of nitrogen productivity in the equatorial Pacific

NASA Technical Reports Server (NTRS)

Wilkerson, Frances P.; Dugdale, Richard C.

1992-01-01

During the R/V Wecoma WEC88 cruise that sampled a meridional transect along 150 deg W from 15 deg N to 15 deg S, uptake of nitrate and ammonium by phytoplankton was measured using the stable isotope N-15 with simulated in-situ bottle incubations and shipboard mass spectrometry. A set of 25 daily productivity stations showed the influence of equatorial upwelling on nitrate distribution and N-15 uptake in a band from 6 deg N to 7.5 deg S compared with the oligotrophic waters to the north and south, with the highest values of nitrate uptake occurring at the equator. During a 5-day time series at the equator, there was an increase in nitrate accompanied by increased nitrate uptake. Interestingly, nitrate uptake rates (equivalent to new production rates) at the equator were lower than those predicted by previous investigators. Holdover experiments and uptake versus irradiance curves showed that the phytoplankton was in an early stage of metabolic adaptation and that can be a contributing factor.

INTERREGIONAL COMPARISON OF NUTRIENT UPTAKE RATES IN MANAGED AND OLD-GROWTH WATERSHEDS

EPA Science Inventory

We compared nutrient uptake rates to examine the effect of timber harvest on streams. From 1999-2002, nutrient additions were conducted in 50 stream reaches in 4 ecoregions (southern Blue Ridge, NC, Ouachita Mountains, AR, Cascade Mountains, OR, and the redwood forests of the Co...

Linkages Between Terrestrial Carbon Uptake and Interannual Climate Variability over the Texas-northern Mexico High Plains

NASA Astrophysics Data System (ADS)

Parazoo, N.; Barnes, E. A.; Worden, J.; Harper, A. B.; Bowman, K. W.; Frankenberg, C.

2014-12-01

The Texas-northern Mexico high plains experienced record drought conditions in 2011 during strong negative phases of ENSO and the NAO. Given predictions of increased frequency and severity of drought under projected climate change [e.g., Reichstein et al., 2013] and recent findings of CO2 growth rate sensitivity to interannual variability of carbon uptake in semi-arid ecosystems [Poulter et al., 2014], we investigate the response of carbon uptake in the Texas high plains to interannual climate variability with the goal of improved mechanistic understanding of climate-carbon cycle links. Specifically, we examine (1) observed tendencies in regional scale carbon uptake and soil moisture from 2010 to 2011 using satellite observations of gross primary production (GPP) (from plant fluorescence) from GOSAT and soil moisture from SMOS, and (2) the interannual relationship between GPP and ENSO & NAO variability using terrestrial biosphere simulations from 1950-2012. Observations reveal widespread decline of GPP in 2011 (0.42 +/- 0.04 Pg C yr-1) correlated with negative soil moisture tendencies (r = 0.85 +/- 0.21) which leads to corresponding declines in net carbon uptake and transpiration (according to model simulations). Further examination of model results over the period 1950-2012 indicates that negative GPP anomalies are linked systematically to winter and spring precipitation deficits associated with overlapping negative phases of winter NAO and ENSO, with increasing magnitude of negative anomalies in strong La Niña years. Furthermore, the strongest decline of GPP, carbon uptake, and transpiration on record occurred during the 2011 drought and were associated with extreme negative phases of ENSO and NAO, with 2011 being the only year since 1950 that both indices exceeded 1 σ standard deviation.

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.

Role of reactive oxygen species in contraction-mediated glucose transport in mouse skeletal muscle

PubMed Central

Sandström, Marie E; Zhang, Shi-Jin; Bruton, Joseph; Silva, José P; Reid, Michael B; Westerblad, Håkan; Katz, Abram

2006-01-01

Exercise increases glucose transport into skeletal muscle via a pathway that is poorly understood. We investigated the role of endogenously produced reactive oxygen species (ROS) in contraction-mediated glucose transport. Repeated contractions increased 2-deoxyglucose (2-DG) uptake roughly threefold in isolated, mouse extensor digitorum longus (fast-twitch) muscle. N-Acetylcysteine (NAC), a non-specific antioxidant, inhibited contraction-mediated 2-DG uptake by ∼50% (P < 0.05 versus control values), but did not significantly affect basal 2-DG uptake or the uptake induced by insulin, hypoxia or 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR, which mimics AMP-mediated activation of AMP-activated protein kinase, AMPK). Ebselen, a glutathione peroxidase mimetic, also inhibited contraction-mediated 2-DG uptake (by almost 60%, P < 0.001 versus control values). Muscles from mice overexpressing Mn2+-dependent superoxide dismutase, which catalyses H2O2 production from superoxide anions, exhibited a ∼25% higher rate of contraction-mediated 2-DG uptake versus muscles from wild-type control mice (P < 0.05). Exogenous H2O2 induced oxidative stress, as judged by an increase in the [GSSG]/[GSH + GSSG] (reduced glutathione + oxidized glutathione) ratio to 2.5 times control values, and this increase was substantially blocked by NAC. Similarly, NAC significantly attenuated contraction-mediated oxidative stress as judged by measurements of glutathione status and the intracellular ROS level with the fluorescent indicator 5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein (P < 0.05). Finally, contraction increased AMPK activity and phosphorylation ∼10-fold, and NAC blocked ∼50% of these changes. These data indicate that endogenously produced ROS, possibly H2O2 or its derivatives, play an important role in contraction-mediated activation of glucose transport in fast-twitch muscle. PMID:16777943

GFPT2-expressing cancer-associated fibroblasts mediate metabolic reprogramming in human lung adenocarcinoma.

PubMed

Zhang, Weiruo; Bouchard, Gina; Yu, Alice; Shafiq, Majid; Jamali, Mehran; Shrager, Joseph B; Ayers, Kelsey; Bakr, Shaimaa; Gentles, Andrew J; Diehn, Maximilian; Quon, Andrew; West, Robert B; Nair, Viswam; van de Rijn, Matt; Napel, Sandy; Plevritis, Sylvia K

2018-05-14

Metabolic reprogramming of the tumor microenvironment is recognized as a cancer hallmark. To identify new molecular processes associated with tumor metabolism, we analyzed the transcriptome of bulk and flow-sorted human primary non-small cell lung cancer (NSCLC) together with 18FDG-positron emission tomography scans, which provide a clinical measure of glucose uptake. Tumors with higher glucose uptake were functionally enriched for molecular processes associated with invasion in adenocarcinoma (AD) and cell growth in squamous cell carcinoma (SCC). Next, we identified genes correlated to glucose uptake that were predominately overexpressed in a single cell-type comprising the tumor microenvironment. For SCC, most of these genes were expressed by malignant cells, whereas in AD they were predominately expressed by stromal cells, particularly cancer-associated fibroblasts (CAFs). Among these AD genes correlated to glucose uptake, we focused on Glutamine-Fructose-6-Phosphate Transaminase 2 (GFPT2), which codes for the Glutamine-Fructose-6-Phosphate Aminotransferase 2 (GFAT2), a rate-limiting enzyme of the hexosamine biosynthesis pathway (HBP), which is responsible for glycosylation. GFPT2 was predictive of glucose uptake independent of GLUT1, the primary glucose transporter, and was prognostically significant at both gene and protein level. We confirmed that normal fibroblasts transformed to CAF-like cells, following TGF-β treatment, upregulated HBP genes, including GFPT2, with less change in genes driving glycolysis, pentose phosphate pathway and TCA cycle. Our work provides new evidence of histology-specific tumor-stromal properties associated with glucose uptake in NSCLC and identifies GFPT2 as a critical regulator of tumor metabolic reprogramming in AD. Copyright ©2018, American Association for Cancer Research.

Analysis of optimal phenotypic space using elementary modes as applied to Corynebacterium glutamicum

PubMed Central

Gayen, Kalyan; Venkatesh, KV

2006-01-01

Background Quantification of the metabolic network of an organism offers insights into possible ways of developing mutant strain for better productivity of an extracellular metabolite. The first step in this quantification is the enumeration of stoichiometries of all reactions occurring in a metabolic network. The structural details of the network in combination with experimentally observed accumulation rates of external metabolites can yield flux distribution at steady state. One such methodology for quantification is the use of elementary modes, which are minimal set of enzymes connecting external metabolites. Here, we have used a linear objective function subject to elementary modes as constraint to determine the fluxes in the metabolic network of Corynebacterium glutamicum. The feasible phenotypic space was evaluated at various combinations of oxygen and ammonia uptake rates. Results Quantification of the fluxes of the elementary modes in the metabolism of C. glutamicum was formulated as linear programming. The analysis demonstrated that the solution was dependent on the criteria of objective function when less than four accumulation rates of the external metabolites were considered. The analysis yielded feasible ranges of fluxes of elementary modes that satisfy the experimental accumulation rates. In C. glutamicum, the elementary modes relating to biomass synthesis through glycolysis and TCA cycle were predominantly operational in the initial growth phase. At a later time, the elementary modes contributing to lysine synthesis became active. The oxygen and ammonia uptake rates were shown to be bounded in the phenotypic space due to the stoichiometric constraint of the elementary modes. Conclusion We have demonstrated the use of elementary modes and the linear programming to quantify a metabolic network. We have used the methodology to quantify the network of C. glutamicum, which evaluates the set of operational elementary modes at different phases of fermentation. The methodology was also used to determine the feasible solution space for a given set of substrate uptake rates under specific optimization criteria. Such an approach can be used to determine the optimality of the accumulation rates of any metabolite in a given network. PMID:17038164

Inhibition of Phosphate Uptake in Corn Roots by Aluminum-Fluoride Complexes1

PubMed Central

Façanha, Arnoldo Rocha; Okorokova-Façanha, Anna L.

2002-01-01

F forms stable complexes with Al at conditions found in the soil. Fluoroaluminate complexes (AlFx) have been widely described as effective analogs of inorganic phosphate (Pi) in Pi-binding sites of several proteins. In this work, we explored the possibility that the phytotoxicity of AlFx reflects their activity as Pi analogs. For this purpose, 32P-labeled phosphate uptake by excised roots and plasma membrane H+-ATPase activity were investigated in an Al-tolerant variety of maize (Zea mays L. var. dwarf hybrid), either treated or not with AlFx. In vitro, AlFx competitively inhibited the rate of root phosphate uptake as well as the H+-ATPase activity. Conversely, pretreatment of seedlings with AlFx in vivo promoted no effect on the H+-ATPase activity, whereas a biphasic effect on Pi uptake by roots was observed. Although the initial rate of phosphate uptake by roots was inhibited by AlFx pretreatment, this situation changed over the following minutes as the rate of uptake increased and a pronounced stimulation in subsequent 32Pi uptake was observed. This kinetic behavior suggests a reversible and competitive inhibition of the phosphate transporter by fluoroaluminates. The stimulation of root 32Pi uptake induced by AlFx pretreatment was tentatively interpreted as a phosphate starvation response. This report places AlF3 and AlF4− among Al-phytotoxic species and suggests a mechanism of action where the accumulation of Pi-mimicking fluoroaluminates in the soil may affect the phosphate absorption by plants. The biochemical, physiological, and environmental significance of these findings is discussed. PMID:12177489

Relationship between root water uptake and soil respiration: A modeling perspective

NASA Astrophysics Data System (ADS)

Teodosio, Bertrand; Pauwels, Valentijn R. N.; Loheide, Steven P.; Daly, Edoardo

2017-08-01

Soil moisture affects and is affected by root water uptake and at the same time drives soil CO2 dynamics. Selecting root water uptake formulations in models is important since this affects the estimation of actual transpiration and soil CO2 efflux. This study aims to compare different models combining the Richards equation for soil water flow to equations describing heat transfer and air-phase CO2 production and flow. A root water uptake model (RWC), accounting only for root water compensation by rescaling water uptake rates across the vertical profile, was compared to a model (XWP) estimating water uptake as a function of the difference between soil and root xylem water potential; the latter model can account for both compensation (XWPRWC) and hydraulic redistribution (XWPHR). Models were compared in a scenario with a shallow water table, where the formulation of root water uptake plays an important role in modeling daily patterns and magnitudes of transpiration rates and CO2 efflux. Model simulations for this scenario indicated up to 20% difference in the estimated water that transpired over 50 days and up to 14% difference in carbon emitted from the soil. The models showed reduction of transpiration rates associated with water stress affecting soil CO2 efflux, with magnitudes of soil CO2 efflux being larger for the XWPHR model in wet conditions and for the RWC model as the soil dried down. The study shows the importance of choosing root water uptake models not only for estimating transpiration but also for other processes controlled by soil water content.

Nitrate concentration effects on NO3-N uptake and reduction, growth, and fruit yield in strawberry

NASA Technical Reports Server (NTRS)

Darnell, R. L.; Stutte, G. W.; Sager, J. C. (Principal Investigator)

2001-01-01

Strawberries (Fragaria xananassa Duch. 'Osogrande') were grown hydroponically with three NO3-N concentrations (3.75, 7.5, or 15.0 mM) to determine effects of varying concentration on NO3-N uptake and reduction rates, and to relate these processes to growth and fruit yield. Plants were grown for 32 weeks, and NO3-N uptake and nitrate reductase (NR) activities in roots and shoots were measured during vegetative and reproductive growth. In general, NO3-N uptake rates increased as NO3-N concentration in the hydroponics system increased. Tissue NO3- concentration also increased as external NO3-N concentration increased, reflecting the differences in uptake rates. There was no effect of external NO3-N concentration on NR activities in leaves or roots during either stage of development. Leaf NR activity averaged approximately 360 nmol NO2 formed/g fresh weight (FW)/h over both developmental stages, while NR activity in roots was much lower, averaging approximately 115 nmol NO2 formed/g FW/h. Vegetative organ FW, dry weight (DW), and total fruit yield were unaffected by NO3-N concentration. These data suggest that the inability of strawberry to increase growth and fruit yield in response to increasing NO3-N concentrations is not due to limitations in NO3-N uptake rates, but rather to limitations in NO3- reduction and/or assimilation in both roots and leaves.

Development of an inflammation imaging tracer, 111In-DOTA-DAPTA, targeting chemokine receptor CCR5 and preliminary evaluation in an ApoE-/- atherosclerosis mouse model.

PubMed

Wei, Lihui; Petryk, Julia; Gaudet, Chantal; Kamkar, Maryam; Gan, Wei; Duan, Yin; Ruddy, Terrence D

2018-02-07

Chemokine receptor 5 (CCR5) plays an important role in atherosclerosis. Our objective was to develop a SPECT tracer targeting CCR5 for imaging plaque inflammation by radiolabeling D-Ala-peptide T-amide (DAPTA), a CCR5 antagonist, with 111 In. 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) conjugated DAPTA (DOTA-DAPTA) was labeled with 111 In. Cell uptake studies were conducted in U87-CD4-CCR5 and U87-MG cells. Biodistribution was determined in C57BL/6 mice. Autoradiography, en face and Oil Red O (ORO) imaging studies were performed in ApoE -/- mice. DOTA-DAPTA was radiolabeled with 111 In with high radiochemical purity (> 98%) and specific activity (70 MBq·nmol). 111 In-DOTA-DAPTA exhibited fast blood and renal clearance and high spleen uptake. The U87-CD4-CCR5 cells had significantly higher uptake in comparison to the U87-MG cells. The cell uptake was reduced by three times with DAPTA, indicating the receptor specificity of the uptake. Autoradiographic images showed significantly higher lesion uptake of 111 In-DOTA-DAPTA in ApoE -/- mice than that in C57BL/6 mice. The tracer uptake in 4 month old ApoE -/- high fat diet (HFD) mice with blocking agent was twofold lower than the same mice without the blocking agent, demonstrating the specificity of the tracer for the CCR5 receptor. 111 In-DOTA-DAPTA, specifically targeting chemokine receptor CCR5, is a potential SPECT agent for imaging inflammation in atherosclerosis.

Applicability of avidin protein coated mesoporous silica nanoparticles as drug carriers in the lung

NASA Astrophysics Data System (ADS)

van Rijt, S. H.; Bölükbas, D. A.; Argyo, C.; Wipplinger, K.; Naureen, M.; Datz, S.; Eickelberg, O.; Meiners, S.; Bein, T.; Schmid, O.; Stoeger, T.

2016-04-01

Mesoporous silica nanoparticles (MSNs) exhibit unique drug delivery properties and are thus considered as promising candidates for next generation nano-medicines. In particular, inhalation into the lungs represents a direct, non-invasive delivery route for treating lung disease. To assess MSN biocompatibility in the lung, we investigated the bioresponse of avidin-coated MSNs (MSN-AVI), as well as aminated (uncoated) MSNs, after direct application into the lungs of mice. We quantified MSN distribution, clearance rate, cell-specific uptake, and inflammatory responses to MSNs within one week after instillation. We show that amine-functionalized (MSN-NH2) particles are not taken up by lung epithelial cells, but induced a prolonged inflammatory response in the lung and macrophage cell death. In contrast, MSN-AVI co-localized with alveolar epithelial type 1 and type 2 cells in the lung in the absence of sustained inflammatory responses or cell death, and showed preferential epithelial cell uptake in in vitro co-cultures. Further, MSN-AVI particles demonstrated uniform particle distribution in mouse lungs and slow clearance rates. Thus, we provide evidence that avidin functionalized MSNs (MSN-AVI) have the potential to serve as versatile biocompatible drug carriers for lung-specific drug delivery.Mesoporous silica nanoparticles (MSNs) exhibit unique drug delivery properties and are thus considered as promising candidates for next generation nano-medicines. In particular, inhalation into the lungs represents a direct, non-invasive delivery route for treating lung disease. To assess MSN biocompatibility in the lung, we investigated the bioresponse of avidin-coated MSNs (MSN-AVI), as well as aminated (uncoated) MSNs, after direct application into the lungs of mice. We quantified MSN distribution, clearance rate, cell-specific uptake, and inflammatory responses to MSNs within one week after instillation. We show that amine-functionalized (MSN-NH2) particles are not taken up by lung epithelial cells, but induced a prolonged inflammatory response in the lung and macrophage cell death. In contrast, MSN-AVI co-localized with alveolar epithelial type 1 and type 2 cells in the lung in the absence of sustained inflammatory responses or cell death, and showed preferential epithelial cell uptake in in vitro co-cultures. Further, MSN-AVI particles demonstrated uniform particle distribution in mouse lungs and slow clearance rates. Thus, we provide evidence that avidin functionalized MSNs (MSN-AVI) have the potential to serve as versatile biocompatible drug carriers for lung-specific drug delivery. Electronic supplementary information (ESI) available: Synthesis of MSN particles. Characterisation of MSN particles (Fig. S1 and S2), DLS measurements of MSNs over time, lymphocyte and PMN cell count after MSN exposure (Fig. S3). Toxicity in BAL cytospins controls, phalloidin staining on BAL cytospins of MSN-NH2 exposed mice (Fig. S4), nanoparticle distribution in lung cryo-slices of Balb/c mice exposed to 100 μg MSNs (Fig. S5). Balb/c mice cryo-slices exposed to MSN-AVI for 1 or 7 days, co-stained with alveolar epithelial cell type 1 marker or with alveolar epithelial cell type 2 marker (Fig. S6), DiD selective labeling in a co-culture set-up (Fig. S7). See DOI: 10.1039/c5nr04119h

A quantitative model for oxygen uptake and release in a family of hemeproteins.

PubMed

Bustamante, Juan P; Szretter, María E; Sued, Mariela; Martí, Marcelo A; Estrin, Darío A; Boechi, Leonardo

2016-06-15

Hemeproteins have many diverse functions that largely depend on the rate at which they uptake or release small ligands, like oxygen. These proteins have been extensively studied using either simulations or experiments, albeit only qualitatively and one or two proteins at a time. We present a physical-chemical model, which uses data obtained exclusively from computer simulations, to describe the uptake and release of oxygen in a family of hemeproteins, called truncated hemoglobins (trHbs). Through a rigorous statistical analysis we demonstrate that our model successfully recaptures all the reported experimental oxygen association and dissociation kinetic rate constants, thus allowing us to establish the key factors that determine the rates at which these hemeproteins uptake and release oxygen. We found that internal tunnels as well as the distal site water molecules control ligand uptake, whereas oxygen stabilization by distal site residues controls ligand release. Because these rates largely determine the functions of these hemeproteins, these approaches will also be important tools in characterizing the trHbs members with unknown functions. lboechi@ic.fcen.uba.ar Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Oxygen uptake on-kinetics during six-minute walk test predicts short-term outcomes after off-pump coronary artery bypass surgery.

PubMed

Rocco, Isadora Salvador; Viceconte, Marcela; Pauletti, Hayanne Osiro; Matos-Garcia, Bruna Caroline; Marcondi, Natasha Oliveira; Bublitz, Caroline; Bolzan, Douglas William; Moreira, Rita Simone Lopes; Reis, Michel Silva; Hossne, Nelson Américo; Gomes, Walter José; Arena, Ross; Guizilini, Solange

2017-12-26

We aimed to investigate the ability of oxygen uptake kinetics to predict short-term outcomes after off-pump coronary artery bypass grafting. Fifty-two patients aged 60.9 ± 7.8 years waiting for off-pump coronary artery bypass surgery were evaluated. The 6-min walk test distance was performed pre-operatively, while simultaneously using a portable cardiopulmonary testing device. The transition of oxygen uptake kinetics from rest to exercise was recorded to calculate oxygen uptake kinetics fitting a monoexponential regression model. Oxygen uptake at steady state, constant time, and mean response time corrected by work rate were analysed. Short-term clinical outcomes were evaluated during the early post-operative of off-pump coronary artery bypass surgery. Multivariate analysis showed body mass index, surgery time, and mean response time corrected by work rate as independent predictors for short-term outcomes. The optimal mean response time corrected by work rate cut-off to estimate short-term clinical outcomes was 1.51 × 10 -3  min 2 /ml. Patients with slower mean response time corrected by work rate demonstrated higher rates of hypertension, diabetes, EuroSCOREII, left ventricular dysfunction, and impaired 6-min walk test parameters. The per cent-predicted distance threshold of 66% in the pre-operative was associated with delayed oxygen uptake kinetics. Pre-operative oxygen uptake kinetics during 6-min walk test predicts short-term clinical outcomes after off-pump coronary artery bypass surgery. From a clinically applicable perspective, a threshold of 66% of pre-operative predicted 6-min walk test distance indicated slower kinetics, which leads to longer intensive care unit and post-surgery hospital length of stay. Implications for rehabilitation Coronary artery bypass grafting is a treatment aimed to improve expectancy of life and prevent disability due to the disease progression; The use of pre-operative submaximal functional capacity test enabled the identification of patients with high risk of complications, where patients with delayed oxygen uptake kinetics exhibited worse short-term outcomes; Our findings suggest the importance of the rehabilitation in the pre-operative in order to "pre-habilitate" the patients to the surgical procedure; Faster oxygen uptake on-kinetics could be achieved by improving the oxidative capacity of muscles and cardiovascular conditioning through rehabilitation, adding better results following cardiac surgery.

Precipitation of CaCO3 due to the Uptake of CO2 in Aqueous Solutions - Mechanisms and Rates

NASA Astrophysics Data System (ADS)

Dietzel, M.; Purgstaller, B.; Rinder, T.; Niedermayr, A.

2012-12-01

In natural and man-made environments the exchange of CO2 between aqueous solutions and the atmosphere frequently induces precipitation of CaCO3 polymorphs. Liberation of gaseous CO2 is well known to induce carbonate formation and extensively studied. In contrast significant gaps of knowledge exist with respect to the combined CO2 uptake and CaCO3 formation, although it is known to be highly valid for many natural and man-made surroundings causing e.g. travertine and scaling in analogy to CO2 liberation. Recently CO2 uptake is also discussed for biomineralization issues and debated for CO2 sequestration by using alkaline residue materials. In the present study CO2 uptake and CaCO3 precipitation mechanisms and rates were experimentally studied by diffusion of CO2 through a polyethylene membrane from an inner to an outer solution containing carbonic acid and CaCl2 (10 mM), respectively. The pH of the outer solution was kept constant between 8.3 and 11.5 by pH stat. technique (25°C). At a critical Ion Activity Product (IAP) CaCO3 is formed in the outer solution. The NaOH titration curve and Ca2+ concentrations reflect CO2 uptake and CaCO3 precipitation rates. To discover the impact of a drift in pH due to CO2 uptake on CaCO3 precipitation hydrogeochemical modeling was applied. XRD, (micro)Raman pattern and SEM imaging reveal the formation of calcite and vaterite at pH 8.3 and 9, whereas at pH > 10 vaterite is additionally formed. However at a given pH the formation of individual CaCO3 polymorphs strongly depends on the CO2 uptake rate (adjusted by membrane thickness), which controls carbonate accumulation in the solution. At elevated pH of the outer solution the uptake rate of CO2 is significantly higher and less time for nucleation of CaCO3 is required compared to lower pH. Surprisingly at the total experimental time of ≈ 20 h the amount of precipitated CaCO3 is similar for all experiments. This can be explained by significant higher CaCO3 precipitation rates at low versus high pH if once a critical IAP is reached. If a drift in pH is permitted the internal Pco2 value can be used as a reliable proxy to evaluate whether uptake of CO2 results in an increase or decrease of IAP with a threshold value of 10-6.15 atm at 25°C (pH ≈ 11). The obtained relationships for CaCO3 formation through CO2 uptake are discussed for selected alkaline environments.

Age alters uptake pattern of organic and inorganic nitrogen by rubber trees.

PubMed

Liu, Min; Xu, Fanzhen; Xu, Xingliang; Wanek, Wolfgang; Yang, Xiaodong

2018-04-05

Several studies have explored plant nutrient acquisition during ecosystem succession, but it remains unclear how age affects nitrogen (N) acquisition by the same tree species. Clarifying the age effect will be beneficial to fertilization management through improving N-use efficiency and reducing the risk of environmental pollution due to NO3- leaching. To clarify the effect of age on N uptake, rubber (Hevea brasiliensis (Willd. ex A. Juss.) Muell. Arg.) plantations of five ages (7, 16, 24, 32 and 49 years) were selected in Xishuangbanna of southern China for brief 15N exposures of intact roots using field hydroponic experiments. 15N-labeled NH4+, NO3- or glycine were applied in this study. All targeted rubber trees uptake rates followed an order of NH4+ > glycine > NO3-. As age increased, NH4+ uptake increased first and then decreased sharply, partly consistent with the pattern of soil NH4+ concentrations. Uptake of glycine decreased first and then increased gradually, while no significant change of NO3- uptake rates existed with increasing age. Overall, rubber trees with ages from 7 to 49 years all showed a preference for NH4+ uptake. Young rubber trees (7 and 16 years) had higher NH4+ and lower glycine preferences than older trees (24, 32 and 49 years). Mycorrhizal colonization rates of rubber trees were higher in intermediately aged plantations (16, 24 and 32 years) than in plantations aged 7 and 49 years. A positive relationship was observed between arbuscular mycorrhizal colonization rates and NO3- preference. The results from this study demonstrate that rubber trees do not change their preference for NH4+ but strongly decreased their reliance on it with age. These findings indicate that the shift of N uptake patterns with age should be taken into account for rubber fertilization management to improve N-use efficiency and reduce the risk of environmental pollution during rubber production.

Social disparities in access to breast and cervical cancer screening by women living in Spain.

PubMed

Ricardo-Rodrigues, I; Jiménez-García, R; Hernández-Barrera, V; Carrasco-Garrido, P; Jiménez-Trujillo, I; López de Andrés, A

2015-07-01

To describe uptake of breast and cervical cancer screening by women living in Spain, analyse the possible associated social and health factors, and compare uptake rates with those obtained in previous surveys. Cross-sectional study using data from the 2011 Spanish national health survey. Uptake of breast cancer screening was analysed by asking women aged 40-69 years whether they had undergone mammography in the previous two years. Uptake of cervical cancer screening was analysed by asking women aged 25-65 years whether they had undergone cervical cytology in the previous three years. Independent variables included sociodemographic characteristics, and variables related to health status and lifestyle. Seventy-two percent of women had undergone mammography in the previous two years. Having private health insurance increased the probability of breast screening uptake four-fold [odds ratio (OR) 3.96, 95% confidence interval (CI) 2.71-5.79], and being an immigrant was a negative predictor for breast screening uptake. Seventy percent of women had undergone cervical cytology in the previous three years. Higher-educated women were more likely to have undergone cervical cancer screening (OR 2.59, 95% CI 1.97-3.40), and obese women and women living in rural areas were less likely to have undergone cervical cancer screening. There have been no relevant improvements in uptake rates of either breast or cervical cancer screening since 2006. Uptake of breast and cervical cancer screening could be improved in Spain, and uptake rates have stagnated over recent years. Social disparities have been detected with regard to access to these screening tests, indicating that it is necessary to continue researching and optimizing prevention programmes in order to improve uptake and reduce these disparities. Copyright © 2015 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Impact of Gender-Specific Human Papillomavirus Vaccine Recommendations on Uptake of Other Adolescent Vaccines: Analysis of the NIS-Teen (2008-2012).

PubMed

Bednarczyk, Robert A; Orenstein, Walter A; Omer, Saad B

In the United States, human papillomavirus vaccination was routinely recommended for adolescent females in 2006 and provisionally recommended for adolescent males in 2009. We evaluated the hypothesis that gender-specific human papillomavirus vaccination recommendations would impact gender-specific uptake of other vaccines using National Immunization Survey-Teen public use data sets (2008-2012). Female adolescents had higher coverage than males of at least 1 other adolescent vaccine in 2008 (3.0% higher) and 2009 (4.3% higher). Gender differences abated in 2010, 2011, and 2012 (0.2%, 0.9%, and 0.4%, respectively). To evaluate unintended consequences of gender-based recommendations, countries with female-only human papillomavirus vaccination recommendations should evaluate gender-specific uptake of other adolescent vaccines.

Combining endocytic and freezing-induced trehalose uptake for cryopreservation of mammalian cells.

PubMed

Zhang, Miao; Oldenhof, Harriëtte; Sieme, Harald; Wolkers, Willem F

2017-01-01

Fibroblasts take up trehalose during freezing and thawing, which facilitates cryosurvival of the cells. The aim of this study was to investigate if trehalose uptake via fluid-phase endocytosis prefreeze increases cryosurvival. To determine endocytic trehalose uptake in attached as well as suspended fibroblasts, intracellular trehalose concentrations were determined during incubation at 37°C using an enzymatically based trehalose assay. In addition, freezing-induced trehalose uptake of extracellularly added trehalose was determined. Cryosurvival rates were determined via trypan blue staining. Intracellular trehalose contents of attached as well as suspended cells were found to increase linearly with time, consistent with fluid-phase endocytosis. Furthermore, the intracellular trehalose concentration increased with increasing extracellular trehalose concentration (0-100 mM) in a linear fashion. Prefreeze loading of cells with trehalose via fluid-phase endocytosis only showed increased cryosurvival rates at extracellular trehalose concentrations lower than 50 mM in the cryopreservation medium. To obtain satisfactory cryosurvival rates after endocytic preloading, extracellular trehalose is needed to prevent efflux of trehalose during freezing and thawing and for freezing-induced trehalose uptake. At trehalose concentrations greater than 100 mM, cryosurvival rates were similar or slightly higher if cells were not loaded with trehalose prefreeze. Cells that were grown in the presence of trehalose showed a tendency to aggregate after harvesting. It is concluded that it is particularly freezing-induced trehalose uptake that facilitates cryosurvival when trehalose is used as the sole cryoprotectant for cryopreservation of fibroblasts. Preloading with trehalose does not increase cryosurvival rates if trehalose is also added as extracellular protectant. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:229-230, 2017. © 2016 American Institute of Chemical Engineers.

Laboratory investigation of inorganic carbon uptake by cryoconite debris from Werenskioldbreen, Svalbard

NASA Astrophysics Data System (ADS)

Stibal, Marek; Tranter, Martyn

2007-12-01

Laboratory experiments were undertaken to determine the inorganic carbon uptake rate and the interactions between photosynthesis and water chemistry, particularly pH and nutrient concentrations, for cryoconite debris from Werenskioldbreen, a well-researched Svalbard glacier. Microorganisms in cryoconite debris took up inorganic carbon at rates between 0.6 and 15 μg C L-1 h-1 and fixed it as organic carbon. Cyanobacterial photosynthesis (75-93%) was the main process responsible for inorganic carbon fixation, while heterotrophic uptake (6-15%) only accounted for a minor part. The microbes in cryoconite debris were active shortly after melt and fixed carbon as long as there were favorable conditions. They were not truly psychrophilic: their physiological optimum temperature was higher than is prevalent in cryoconite holes. The pH was also a factor affecting photosynthesis in the cryoconite slurry. The highest dissolved inorganic carbon (DIC) uptake rates per liter of slurry occurred at pH ˜7, and there was a significant correlation between the initial pH and DIC fixation on a per cell basis, showing increasing DIC uptake rates when pH increased from ˜5.5 to 9. Inorganic carbon fixation resulted in an increased pH in solution. However, the microbes were able to photosynthesize in a wide range of pH from ˜4 to ˜10. The average C:N:P molar ratios in solution were ˜350:75:1. Unlike nitrogen, phosphorus concentrations decreased with increasing carbon uptake, and when the rate approached ˜15 μg C L-1 h-1, all available dissolved phosphorus was utilized within 6 h. Hence phosphorus is probably biolimiting in this system.

Biomass Content Governs Fermentation Rate in Nitrogen-Deficient Wine Musts

PubMed Central

Varela, Cristian; Pizarro, Francisco; Agosin, Eduardo

2004-01-01

Problematic fermentations are common in the wine industry. Assimilable nitrogen deficiency is the most prevalent cause of sluggish fermentations and can reduce fermentation rates significantly. A lack of nitrogen diminishes a yeast's metabolic activity, as well as the biomass yield, although it has not been clear which of these two interdependent factors is more significant in sluggish fermentations. Under winemaking conditions with different initial nitrogen concentrations, metabolic flux analysis was used to isolate the effects. We quantified yeast physiology and identified key metabolic fluxes. We also performed cell concentration experiments to establish how biomass yield affects the fermentation rate. Intracellular analysis showed that trehalose accumulation, which is highly correlated with ethanol production, could be responsible for sustaining cell viability in nitrogen-poor musts independent of the initial assimilable nitrogen content. Other than the higher initial maintenance costs in sluggish fermentations, the main difference between normal and sluggish fermentations was that the metabolic flux distributions in nitrogen-deficient cultures revealed that the specific sugar uptake rate was substantially lower. The results of cell concentration experiments, however, showed that in spite of lower sugar uptake, adding biomass from sluggish cultures not only reduced the time to finish a problematic fermentation but also was less likely to affect the quality of the resulting wine as it did not alter the chemistry of the must. PMID:15184136

Early dynamic imaging in 68Ga- PSMA-11 PET/CT allows discrimination of urinary bladder activity and prostate cancer lesions.

PubMed

Uprimny, Christian; Kroiss, Alexander Stephan; Decristoforo, Clemens; Fritz, Josef; Warwitz, Boris; Scarpa, Lorenza; Roig, Llanos Geraldo; Kendler, Dorota; von Guggenberg, Elisabeth; Bektic, Jasmin; Horninger, Wolfgang; Virgolini, Irene Johanna

2017-05-01

PET/CT with 68 Ga-labelled prostate-specific membrane antigen (PSMA)-ligands has been proven to establish a promising imaging modality in the work-up of prostate cancer (PC) patients with biochemical relapse. Despite a high overall detection rate, the visualisation of local recurrence may be hampered by high physiologic tracer accumulation in the urinary bladder on whole body imaging, usually starting 60 min after injection. This study sought to verify whether early dynamic 68 Ga-PSMA-11 (HBED-CC)PET/CT can differentiate pathologic PC-related tracer uptake from physiologic tracer accumulation in the urinary bladder. Eighty consecutive PC patients referred to 68 Ga -PSMA-11 PET/CT were included in this retrospective analysis (biochemical relapse: n = 64; primary staging: n = 8; evaluation of therapy response/restaging: n = 8). In addition to whole-body PET/CT acquisition 60 min post injection early dynamic imaging of the pelvis in the first 8 min after tracer injection was performed. SUV max of pathologic lesions was calculated and time-activity curves were generated and compared to those of urinary bladder and areas of physiologic tracer uptake. A total of 55 lesions consistent with malignancy on 60 min whole body imaging exhibited also pathologic 68 Ga-PSMA-11 uptake during early dynamic imaging (prostatic bed/prostate gland: n = 27; lymph nodes: n = 12; bone: n = 16). All pathologic lesions showed tracer uptake within the first 3 min, whereas urinary bladder activity was absent within the first 3 min of dynamic imaging in all patients. Suv max was significantly higher in PC lesions in the first 6 min compared to urinary bladder accumulation (p < 0.001). In the subgroup of PC patients with biochemical relapse the detection rate of local recurrence could be increased from 20.3 to 29.7%. Early dynamic imaging in 68 Ga-PSMA-11 PET/CT reliably enables the differentiation of pathologic tracer uptake in PC lesions from physiologic bladder accumulation. Performance of early dynamic imaging in addition to whole body imaging 60 min after tracer injection might improve the detection rate of local recurrence in PC patients with biochemical relapse referred for 68 Ga-PSMA-11 PET/CT.

Increased uptake and improved outcomes of bowel cancer screening with a faecal immunochemical test: results from a pilot study within the national screening programme in England.

PubMed

Moss, Sue; Mathews, Christopher; Day, T J; Smith, Steve; Seaman, Helen E; Snowball, Julia; Halloran, Stephen P

2017-09-01

The National Health Service Bowel Cancer Screening Programme (BCSP) in England uses a guaiac-based faecal occult blood test (gFOBt). A quantitative faecal immunochemical test (FIT) for haemoglobin (Hb) has many advantages, including being specific for human blood, detecting Hb at a much lower concentration with a single faecal sample and improved uptake. In 2014, a large comparative pilot study was performed within BCSP to establish the acceptability and diagnostic performance of FIT. Over a 6-month period, 40 930 (1 in 28) subjects were sent a FIT (OC-SENSOR) instead of a gFOBt. A bespoke FIT package was used to mail FIT sampling devices to and from FIT subjects. All participants positive with either gFOBt or FIT (cut-off 20 µg Hb/g faeces) were referred for follow-up. Subgroup analysis included cut-off concentrations, age, sex, screening history and deprivation quintile. While overall uptake increased by over 7 percentage points with FIT (66.4% vs 59.3%, OR 1.35, 95% CI 1.33 to 1.38), uptake by previous non-responders almost doubled (FIT 23.9% vs gFOBt 12.5%, OR 2.20, 95% CI 2.10 to 2.29). The increase in overall uptake was significantly higher in men than women and was observed across all deprivation quintiles. With the conventional 20 µg/g cut-off, FIT positivity was 7.8% and ranged from 5.7% in 59-64-year-old women to 11.1% in 70-75-year-old men. Cancer detection increased twofold and that for advanced adenomas nearly fivefold. Detection rates remained higher with FIT for advanced adenomas, even at 180 µg Hb/g. Markedly improved participation rates were achieved in a mature gFOBt-based national screening programme and disparities between men and women were reduced. High positivity rates, particularly in men and previous non-respondents, challenge the available colonoscopy resource, but improvements in neoplasia detection are still achievable within this limited resource. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Hepatitis A and B vaccination--the rate of uptake and course completion in patients with hepatitis C.

PubMed

Fredericks, Trinity; Kwan, Kellie; Mak, Donna

2010-10-01

Western Australian general practitioners may order Department of Health funded hepatitis A and B vaccines for patients newly notified with hepatitis C to prevent complications associated with co-infections. The aim of this study was to determine vaccination uptake of hepatitis C patients through this program. We reviewed hepatitis C notifications and hepatitis A and B vaccine orders received in 2007 and 2008 to determine the rate of vaccine uptake and course completion. Vaccination orders for initial doses were received for 37% (448/1209) of patients. Vaccination uptake was positively associated with age and non- Aboriginality. Final vaccination doses were ordered for 30% of patients for whom an initial order had been received. Uptake of hepatitis A and B vaccination was higher than that of similar populations. However, vaccination course completion was low. General practitioners need to emphasise to their patients the importance of completing a vaccine course.

18F-DCFBC Prostate-Specific Membrane Antigen-Targeted PET/CT Imaging in Localized Prostate Cancer: Correlation With Multiparametric MRI and Histopathology.

PubMed

Turkbey, Baris; Mena, Esther; Lindenberg, Liza; Adler, Stephen; Bednarova, Sandra; Berman, Rose; Ton, Anita T; McKinney, Yolanda; Eclarinal, Philip; Hill, Craig; Afari, George; Bhattacharyya, Sibaprasad; Mease, Ronnie C; Merino, Maria J; Jacobs, Paula M; Wood, Bradford J; Pinto, Peter A; Pomper, Martin G; Choyke, Peter L

2017-10-01

To assess the ability of (N-[N-[(S)-1,3-dicarboxypropyl]carbamoyl]-4-F-fluorobenzyl-L-cysteine) (F-DCFBC), a prostate-specific membrane antigen-targeted PET agent, to detect localized prostate cancer lesions in correlation with multiparametric MRI (mpMRI) and histopathology. This Health Insurance Portability and Accountability Act of 1996-compliant, prospective, institutional review board-approved study included 13 evaluable patients with localized prostate cancer (median age, 62.8 years [range, 51-74 years]; median prostate-specific antigen, 37.5 ng/dL [range, 3.26-216 ng/dL]). Patients underwent mpMRI and F-DCFBC PET/CT within a 3 months' window. Lesions seen on mpMRI were biopsied under transrectal ultrasound/MRI fusion-guided biopsy, or a radical prostatectomy was performed. F-DCFBC PET/CT and mpMRI were evaluated blinded and separately for tumor detection on a lesion basis. For PET image analysis, MRI and F-DCFBC PET images were fused by using software registration; imaging findings were correlated with histology, and uptake of F-DCFBC in tumors was compared with uptake in benign prostatic hyperplasia nodules and normal peripheral zone tissue using the 80% threshold SUVmax. A total of 25 tumor foci (mean size, 1.8 cm; median size, 1.5 cm; range, 0.6-4.7 cm) were histopathologically identified in 13 patients. Sensitivity rates of F-DCFBC PET/CT and mpMRI were 36% and 96%, respectively, for all tumors. For index lesions, the largest tumor with highest Gleason score, sensitivity rates of F-DCFBC PET/CT and mpMRI were 61.5% and 92%, respectively. The average SUVmax for primary prostate cancer was higher (5.8 ± 4.4) than that of benign prostatic hyperplasia nodules (2.1 ± 0.3) or that of normal prostate tissue (2.1 ± 0.4) at 1 hour postinjection (P = 0.0033). The majority of index prostate cancers are detected with F-DCFBC PET/CT, and this may be a prognostic indicator based on uptake and staging. However, for detecting prostate cancer with high sensitivity, it is important to combine prostate-specific membrane antigen PET/CT with mpMRI.

Nitrogen Uptake and Denitrification in Restored and Unrestored Streams in Urban Maryland, USA

EPA Science Inventory

There is growing interest in rates of nitrate uptake and denitrification in restored streams to better understand the effects of restoration on nitrogen processing. This study quantified nitrate uptake in 2 restored and 2 unrestored streams in Baltimore, Maryland, U.S.A. using n...

An online self-care education program to support patients after total laryngectomy: feasibility and satisfaction.

PubMed

Cnossen, Ingrid C; van Uden-Kraan, Cornelia F; Eerenstein, Simone E J; Jansen, Femke; Witte, Birgit I; Lacko, Martin; Hardillo, José A; Honings, Jimmie; Halmos, Gyorgy B; Goedhart-Schwandt, Noortje L Q; de Bree, Remco; Leemans, C René; Verdonck-de Leeuw, Irma M

2016-03-01

The purpose of this study was to investigate the feasibility of an online self-care education program supporting early rehabilitation of patients after total laryngectomy (TLPs) and factors associated with satisfaction. Health care professionals (HCPs) were invited to participate and to recruit TLPs. TLPs were informed on the self-care education program "In Tune without Cords" (ITwC) after which they gained access. A study specific survey was used (at baseline T0 and postintervention T1) on TLPs' uptake. Usage, satisfaction (general impression, willingness to use, user-friendliness, satisfaction with self-care advice and strategies, Net Promoter Score (NPS)), sociodemographic, and clinical factors were analyzed. HCPs of 6 out of 9 centers (67% uptake rate) agreed to participate and recruited TLPs. In total, 55 of 75 TLPs returned informed consent and the baseline T0 survey and were provided access to ITwC (73% uptake rate). Thirty-eight of these 55 TLPs used ITwC and completed the T1 survey (69% usage rate). Most (66%) TLPs were satisfied (i.e., score ≥7 (scale 1-10) on 4 survey items) with the self-care education program (mean score 7.2, SD 1.1). NPS was positive (+5). Satisfaction with the self-care education program was significantly associated with (higher) educational level and health literacy skills (P = .004, P = .038, respectively). No significant association was found with gender, age, marital status, employment status, Internet use, Internet literacy, treatment modality, time since total laryngectomy, and quality of life. The online self-care education program ITwC supporting early rehabilitation was feasible in clinical practice. In general, TLPs were satisfied with the program.

Binding, uptake, and release of nicotine by human gingival fibroblasts

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

Hanes, P.J.; Schuster, G.S.; Lubas, S.

1991-02-01

Previous studies of the effects of nicotine on fibroblasts have reported an altered morphology and attachment of fibroblasts to substrates and disturbances in protein synthesis and secretion. This altered functional and attachment response may be associated with changes in the cell membrane resulting from binding of the nicotine, or to disturbances in cell metabolism as a result of high intracellular levels of nicotine. The purpose of the present study, therefore, was to (1) determine whether gingival fibroblasts bound nicotine and if any binding observed was specific or non-specific in nature; (2) determine whether gingival fibroblasts internalized nicotine, and if so,more » at what rate; (3) determine whether gingival fibroblasts also released nicotine back into the extracellular environment; and (4) if gingival fibroblasts release nicotine intact or as a metabolite. Cultures of gingival fibroblasts were prepared from gingival connective tissue biopsies. Binding was evaluated at 4{degree}C using a mixture of {sup 3}H-nicotine and unlabeled nicotine. Specific binding was calculated as the difference between {sup 3}H-nicotine bound in the presence and absence of unlabeled nicotine. The cells bound 1.44 (+/- 0.42) pmols/10(6) cells in the presence of unlabeled nicotine and 1.66 (+/- 0.55) pmols/10(6) cells in the absence of unlabeled nicotine. The difference was not significant. Uptake of nicotine was measured at 37{degree}C after treating cells with {sup 3}H-nicotine for time periods up to 4 hours. Uptake in pmols/10(6) cells was 4.90 (+/- 0.34) at 15 minutes, 8.30 (+/- 0.75) at 30 minutes, 12.28 (+/- 2.62) at 1 hour and 26.31 (+/- 1.15) at 4 hours.« less

Molecular Uptake of Chitooligosaccharides through Chitoporin from the Marine Bacterium Vibrio harveyi

PubMed Central

Suginta, Wipa; Chumjan, Watcharin; Mahendran, Kozhinjampara R.; Janning, Petra; Schulte, Albert; Winterhalter, Mathias

2013-01-01

Background Chitin is the most abundant biopolymer in marine ecosystems. However, there is no accumulation of chitin in the ocean-floor sediments, since marine bacteria Vibrios are mainly responsible for a rapid turnover of chitin biomaterials. The catabolic pathway of chitin by Vibrios is a multi-step process that involves chitin attachment and degradation, followed by chitooligosaccharide uptake across the bacterial membranes, and catabolism of the transport products to fructose-6-phosphate, acetate and NH3. Principal Findings This study reports the isolation of the gene corresponding to an outer membrane chitoporin from the genome of Vibrio harveyi. This porin, expressed in E. coli, (so called VhChiP) was found to be a SDS-resistant, heat-sensitive trimer. Immunoblotting using anti-ChiP polyclonal antibody confirmed the expression of the recombinant ChiP, as well as endogenous expression of the native protein in the V. harveyi cells. The specific function of VhChiP was investigated using planar lipid membrane reconstitution technique. VhChiP nicely inserted into artificial membranes and formed stable, trimeric channels with average single conductance of 1.8±0.13 nS. Single channel recordings at microsecond-time resolution resolved translocation of chitooligosaccharides, with the greatest rate being observed for chitohexaose. Liposome swelling assays showed no permeation of other oligosaccharides, including maltose, sucrose, maltopentaose, maltohexaose and raffinose, indicating that VhChiP is a highly-specific channel for chitooligosaccharides. Conclusion/Significance We provide the first evidence that chitoporin from V. harveyi is a chitooligosaccharide specific channel. The results obtained from this study help to establish the fundamental role of VhChiP in the chitin catabolic cascade as the molecular gateway that Vibrios employ for chitooligosaccharide uptake for energy production. PMID:23383078

A novel Na+/HCO3--codependent choline transporter in the syncytial epithelium of the cestode Hymenolepis diminuta.

PubMed

Webb, R A; Xue, L

1998-02-01

Absorption of exogenous choline by the cestode Hymenolepis diminuta was found to be both Na+- and HCO3--dependent and, at pH 6 to 7, accounted for up to 65% of the total choline uptake. Na+/HCO3- dependent choline uptake was activated at approximately 6 mM HCO3- (EC50 approximately 9 mM), and, above 100 mM Na+, the rate of uptake was directly proportional to the Na+ concentration. Atempts to uncouple Na+-dependent uptake from HCO3--dependent uptake were not successful: K+-depolarization was without effect on HCO3--dependent choline uptake, and use of valinoomycin to hyperpolarize the brush-border membrane resulted in inhibition of uptake. Na-/HCO3--dependent choline uptake was not associated with solvent drag. The Na+/HCO3--dependent choline uptake displayed a Q10 of 6.4 (27 degrees to 37 degrees) and a relatively high activation energy of 126 kJ x mol(-1). At pH 6.0 and 7.0, Na-/HCO3--dependent choline uptake rates were similar, but Na+/HCO3--dependent choline uptake was reduced at pH 5.0. The Na+/HCO3--dependent choline uptake, at pH 7.0, displayed a Kt of approximately 500 microM and a Vmax of 4.01 pmol x mg wet weight(-1) x min(-1). The Na+/HCO3--dependent choline uptake was hemicholinium-3 sensitive, but not significantly inhibited by 200 microM bumetanide, 100 microM amiloride, benzamil, or EIPA or by 1 mM 4,4'-diisothiocyano-2,2'-stilbene disulfonate (DIDS) or 4-acetamido-4'-isothiocvanostilbene-2,2'-disulfonic acid (SITS). Although it remains to be shown that HCO3- uptake is coupled directly to both choline and Na+ uptake, the data suggest that choline up take occurs via choline/Na+/HCO3--co-trans porter.

Aeration control strategies to stimulate simultaneous nitrification-denitrification via nitrite during the formation of aerobic granular sludge.

PubMed

Dobbeleers, Thomas; D'aes, Jolien; Miele, Solange; Caluwé, Michel; Akkermans, Veerle; Daens, Dominique; Geuens, Luc; Dries, Jan

2017-09-01

In this study, a sequencing batch reactor (SBR), treating synthetic wastewater (COD/N = 5), was operated in two stages. During stage I, an aeration control strategy based on oxygen uptake rate (OUR) was applied, to accomplish nitrogen removal via nitrite >80%. In stage II, the development of aerobic granular sludge (AGS) was examined while two aeration control strategies (OUR and pH slope) maintained the nitrite pathway and optimized the simultaneous nitrification-denitrification (SND) performance. Stimulation of slow-growing organisms, (denitrifying) polyphosphate-accumulating organisms (D)PAO and (denitrifying) glycogen-accumulating organisms (D)GAO leads to full granulation (at day 200, SVI 10  = 47.0 mL/g and SVI 30  = 43.1 mL/g). The average biological nutrient removal efficiencies, for nitrogen and phosphorus, were 94.6 and 83.7%, respectively. Furthermore, the benefits of an increased dissolved oxygen concentration (1.0-2.0 mg O 2 /L) were shown as biomass concentrations increased with approximately 2 g/L, and specific ammonium removal rate and phosphorus uptake rate increased with 33 and 44%, respectively. It was shown that the combination of both aeration phase-length control strategies provided an innovative method to achieve SND via nitrite in AGS.

Estuarine microbial food web patterns in a Lake Erie coastal wetland.

PubMed

Lavrentyev, P J; McCarthy, M J; Klarer, D M; Jochem, F; Gardner, W S

2004-11-01

Composition and distribution of planktonic protists were examined relative to microbial food web dynamics (growth, grazing, and nitrogen cycling rates) at the Old Woman Creek (OWC) National Estuarine Research Reserve during an episodic storm event in July 2003. More than 150 protistan taxa were identified based on morphology. Species richness and microbial biomass measured via microscopy and flow cytometry increased along a stream-lake (Lake Erie) transect and peaked at the confluence. Water column ammonium (NH4+) uptake (0.06 to 1.82 microM N h(-1)) and regeneration (0.04 to 0.55 microM N h(-1)) rates, measured using 15NH4+ isotope dilution, followed the same pattern. Large light/dark NH4+ uptake differences were observed in the hypereutrophic OWC interior, but not at the phosphorus-limited Lake Erie site, reflecting the microbial community structural shift from net autotrophic to net heterotrophic. Despite this shift, microbial grazers (mostly choreotrich ciliates, taxon-specific growth rates up to 2.9 d(-1)) controlled nanophytoplankton and bacteria at all sites by consuming 76 to 110% and 56 to 97% of their daily production, respectively, in dilution experiments. Overall, distribution patterns and dynamics of microbial communities in OWC resemble those in marine estuaries, where plankton productivity increases along the river-sea gradient and reaches its maximum at the confluence.

Encystment of parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae coincides with increased metabolic rate and haematocrit in juvenile brown trout (Salmo trutta).

PubMed

Filipsson, Karl; Brijs, Jeroen; Näslund, Joacim; Wengström, Niklas; Adamsson, Marie; Závorka, Libor; Österling, E Martin; Höjesjö, Johan

2017-04-01

Gill parasites on fish are likely to negatively influence their host by inhibiting respiration, oxygen transport capacity and overall fitness. The glochidia larvae of the endangered freshwater pearl mussel (FPM, Margaritifera margaritifera (Linnaeus, 1758)) are obligate parasites on the gills of juvenile salmonid fish. We investigated the effects of FPM glochidia encystment on the metabolism and haematology of brown trout (Salmo trutta Linnaeus, 1758). Specifically, we measured whole-animal oxygen uptake rates at rest and following an exhaustive exercise protocol using intermittent flow-through respirometry, as well as haematocrit, in infested and uninfested trout. Glochidia encystment significantly affected whole-animal metabolic rate, as infested trout exhibited higher standard and maximum metabolic rates. Furthermore, glochidia-infested trout also had elevated levels of haematocrit. The combination of an increased metabolism and haematocrit in infested fish indicates that glochidia encystment has a physiological effect on the trout, perhaps as a compensatory response to the potential respiratory stress caused by the glochidia. When relating glochidia load to metabolism and haematocrit, fish with low numbers of encysted glochidia were the ones with particularly elevated metabolism and haematocrit. Standard metabolic rate decreased with substantial glochidia loads towards levels similar to those of uninfested fish. This suggests that initial effects visible at low levels of encystment may be countered by additional physiological effects at high loads, e.g. potential changes in energy utilization, and also that high numbers of glochidia may restrict oxygen uptake by the gills.

Crassulacean acid metabolism, CO2-recycling, and tissue desiccation in the Mexican epiphyte Tillandsia schiedeana Steud (Bromeliaceae).

PubMed

Martin, C E; Adams, W W

1987-01-01

After 23 days without water in a greenhouse, rates of nocturnal CO2 uptake in Tillandsia schiedeana decreased substantially and maximum rates occurred later in the dark period eventually coinciding with the onset of illumination. Nocturnal CO2 uptake accounted for less than half the total nighttime increase in acidity measured in well-watered plants. With increased tissue desiccation, only 11-12% of measured acid accumulation was attributable to atmospheric CO2 uptake. Plants desiccated for 30 days regained initial levels of nocturnal acid accumulation and CO2 uptake after rehydration for 10h. These results stress the importance of CO2 recycling via CAM in this epiphytic bromeliad, especially during droughts.

Prolonged Maltose-Limited Cultivation of Saccharomyces cerevisiae Selects for Cells with Improved Maltose Affinity and Hypersensitivity

PubMed Central

Jansen, Mickel L. A.; Daran-Lapujade, Pascale; de Winde, Johannes H.; Piper, Matthew D. W.; Pronk, Jack T.

2004-01-01

Prolonged cultivation (>25 generations) of Saccharomyces cerevisiae in aerobic, maltose-limited chemostat cultures led to profound physiological changes. Maltose hypersensitivity was observed when cells from prolonged cultivations were suddenly exposed to excess maltose. This substrate hypersensitivity was evident from massive cell lysis and loss of viability. During prolonged cultivation at a fixed specific growth rate, the affinity for the growth-limiting nutrient (i.e., maltose) increased, as evident from a decreasing residual maltose concentration. Furthermore, the capacity of maltose-dependent proton uptake increased up to 2.5-fold during prolonged cultivation. Genome-wide transcriptome analysis showed that the increased maltose transport capacity was not primarily due to increased transcript levels of maltose-permease genes upon prolonged cultivation. We propose that selection for improved substrate affinity (ratio of maximum substrate consumption rate and substrate saturation constant) in maltose-limited cultures leads to selection for cells with an increased capacity for maltose uptake. At the same time, the accumulative nature of maltose-proton symport in S. cerevisiae leads to unrestricted uptake when maltose-adapted cells are exposed to a substrate excess. These changes were retained after isolation of individual cell lines from the chemostat cultures and nonselective cultivation, indicating that mutations were involved. The observed trade-off between substrate affinity and substrate tolerance may be relevant for metabolic engineering and strain selection for utilization of substrates that are taken up by proton symport. PMID:15066785

mhpT encodes an active transporter involved in 3-(3-hydroxyphenyl)propionate catabolism by Escherichia coli K-12.

PubMed

Xu, Ying; Chen, Bing; Chao, Hongjun; Zhou, Ning-Yi

2013-10-01

Escherichia coli K-12 utilizes 3-(3-hydroxyphenyl)propionate (3HPP) as a sole carbon and energy source. Among the genes in its catabolic cluster in the genome, mhpT was proposed to encode a hypothetical transporter. Since no transporter for 3HPP uptake has been identified, we investigated whether MhpT is responsible for 3HPP uptake. MhpT fused with green fluorescent protein was found to be located at the periphery of cells by confocal microscopy, consistent with localization to the cytoplasmic membrane. Gene knockout and complementation studies clearly indicated that mhpT is essential for 3HPP catabolism in E. coli K-12 W3110 at pH 8.2. Uptake assays with (14)C-labeled substrates demonstrated that strain W3110 and strain W3110ΔmhpT containing recombinant MhpT specifically transported 3HPP but not benzoate, 3-hydroxybenzoate, or gentisate into cells. Energy dependence assays suggested that MhpT-mediated 3HPP transport was driven by the proton motive force. The change of Ala-272 of MhpT to a histidine, surprisingly, resulted in enhanced transport activity, and strain W3110ΔmhpT containing the MhpT A272H mutation had a slightly higher growth rate than the wild-type strain at pH 8.2. Hence, we demonstrated that MhpT is a specific 3HPP transporter and vital for E. coli K-12 W3110 growth on this substrate under basic conditions.

Cadmium uptake by cocoa trees in agroforestry and monoculture systems under conventional and organic management.

PubMed

Gramlich, A; Tandy, S; Andres, C; Chincheros Paniagua, J; Armengot, L; Schneider, M; Schulin, R

2017-02-15

Cadmium (Cd) uptake by cocoa has recently attracted attention, after the European Union (EU) decided to establish values for tolerable Cd concentrations in cocoa products. Bean Cd concentrations from some cocoa provenances, especially from Latin America, were found to exceed these values. Cadmium uptake by cocoa is expected not only to depend on a variety of soil factors, but also on plant and management factors. In this study, we investigated the influence of different production systems on Cd uptake by cocoa in a long-term field trial in the Alto Beni Region of Bolivia, where cocoa trees are grown in monocultures and in agroforestry systems, both under organic and conventional management. Leaf, fruits and roots of two cultivars were sampled from each production system along with soil samples collected around these trees. Leaf, pod husk and bean samples were analysed for Cd, iron (Fe) and zinc (Zn), the roots for mycorrhizal abundance and the soil samples for 'total' and 'available' Cd, Fe and Zn as well as DGT-available Cd and Zn, pH, organic matter, texture, 'available' phosphorus (P) and potassium (K). Only a small part of the variance in bean and pod husk Cd was explained by management, soil and plant factors. Furthermore, the production systems and cultivars alone had no significant influence on leaf Cd. However, we found lower Cd leaf contents in agroforestry systems than in monocultures when analysed in combination with DGT-available soil Cd, cocoa cultivar and soil organic matter. Overall, this model explained 60% of the variance of the leaf Cd concentrations. We explain lower leaf Cd concentrations in agroforestry systems by competition for Cd uptake with other plants. The cultivar effect may be explained by cultivar specific uptake capacities or by a growth effect translating into different uptake rates, as the cultivars were of different size. Copyright © 2016 Elsevier B.V. All rights reserved.

Visualization of angiogenesis during cancer development in the polyoma middle T breast cancer model: molecular imaging with (R)-[11C]PAQ.

PubMed

Samén, Erik; Lu, Li; Mulder, Jan; Thorell, Jan-Olov; Damberg, Peter; Tegnebratt, Tetyana; Holmgren, Lars; Rundqvist, Helene; Stone-Elander, Sharon

2014-03-26

Vascular endothelial growth factor receptor 2 (VEGFR2) is a crucial mediator of tumour angiogenesis. High expression levels of the receptor have been correlated to poor prognosis in cancer patients. Reliable imaging biomarkers for stratifying patients for anti-angiogenic therapy could therefore be valuable for increasing treatment success rates. The aim of this study was to investigate the pharmacokinetics and angiogenesis imaging abilities of the VEGFR2-targeting positron emission tomography (PET) tracer (R)-[11C]PAQ. (R)-[11C]PAQ was evaluated in the mouse mammary tumour virus-polyoma middle T (MMTV-PyMT) model of metastatic breast cancer. Mice at different stages of disease progression were imaged with (R)-[11C]PAQ PET, and results were compared to those obtained with [18 F]FDG PET and magnetic resonance imaging. (R)-[11C]PAQ uptake levels were also compared to ex vivo immunofluorescence analysis of tumour- and angiogenesis-specific biomarkers. Additional pharmacokinetic studies were performed in rat and mouse. A heterogeneous uptake of (R)-[11C]PAQ was observed in the tumorous mammary glands. Ex vivo analysis confirmed the co-localization of areas with high radioactivity uptake and areas with elevated levels of VEGFR2. In some animals, a high focal uptake was observed in the lungs. The lung uptake correlated to metastatic and angiogenic activity, but not to uptake of [18 F]FDG PET. The pharmacokinetic studies revealed a limited metabolism and excretion during the 1-h scan and a distribution of radioactivity mainly to the liver, kidneys and lungs. In rat, a high uptake was additionally observed in adrenal and parathyroid glands. The results indicate that (R)-[11C]PAQ is a promising imaging biomarker for visualization of angiogenesis, based on VEGFR2 expression, in primary tumours and during metastasis development.

Visualization of angiogenesis during cancer development in the polyoma middle T breast cancer model: molecular imaging with (R)-[11C]PAQ

PubMed Central

2014-01-01

Background Vascular endothelial growth factor receptor 2 (VEGFR2) is a crucial mediator of tumour angiogenesis. High expression levels of the receptor have been correlated to poor prognosis in cancer patients. Reliable imaging biomarkers for stratifying patients for anti-angiogenic therapy could therefore be valuable for increasing treatment success rates. The aim of this study was to investigate the pharmacokinetics and angiogenesis imaging abilities of the VEGFR2-targeting positron emission tomography (PET) tracer (R)-[11C]PAQ. Methods (R)-[11C]PAQ was evaluated in the mouse mammary tumour virus-polyoma middle T (MMTV-PyMT) model of metastatic breast cancer. Mice at different stages of disease progression were imaged with (R)-[11C]PAQ PET, and results were compared to those obtained with [18 F]FDG PET and magnetic resonance imaging. (R)-[11C]PAQ uptake levels were also compared to ex vivo immunofluorescence analysis of tumour- and angiogenesis-specific biomarkers. Additional pharmacokinetic studies were performed in rat and mouse. Results A heterogeneous uptake of (R)-[11C]PAQ was observed in the tumorous mammary glands. Ex vivo analysis confirmed the co-localization of areas with high radioactivity uptake and areas with elevated levels of VEGFR2. In some animals, a high focal uptake was observed in the lungs. The lung uptake correlated to metastatic and angiogenic activity, but not to uptake of [18 F]FDG PET. The pharmacokinetic studies revealed a limited metabolism and excretion during the 1-h scan and a distribution of radioactivity mainly to the liver, kidneys and lungs. In rat, a high uptake was additionally observed in adrenal and parathyroid glands. Conclusion The results indicate that (R)-[11C]PAQ is a promising imaging biomarker for visualization of angiogenesis, based on VEGFR2 expression, in primary tumours and during metastasis development. PMID:24670127

Survival analysis of time to uptake of modern contraceptives among sexually active women of reproductive age in Nigeria

PubMed Central

Adebowale, Ayo Stephen; Morhason-Bello, ImranOludare

2015-01-01

Objective To assess the timing of modern contraceptive uptake among married and never-married women in Nigeria. Design A retrospective cross-sectional study. Data and method We used nationally representative 2013 Demographic and Health Survey data in Nigeria. Modern contraceptive uptake time was measured as the period between first sexual intercourse and first use of a modern contraceptive. Non-users of modern contraceptives were censored on the date of the survey. Kaplan–Meier survival curves were used to determine the rate of uptake. A Cox proportional-hazards model was used to determine variables influencing the uptake at 5% significance level. Participants A total of 33 223 sexually active women of reproductive age. Outcome measure Time of uptake of a modern contraceptive after first sexual intercourse. Results The median modern contraceptive uptake time was 4 years in never-married and 14 years among ever-married women. Significant differences in modern contraceptive uptake existed in respondents’ age, location, education and wealth status. Never-married women were about three times more likely to use a modern contraceptive than ever-married women (aHR=3.24 (95% CI 2.82 to 3.65)). Women with higher education were six times more likely to use a modern contraceptive than those without education (aHR=6.18 (95% CI 5.15 to 7.42)). Conclusions The rate of modern contraceptive uptake is low, and timing of contraceptive uptake during or after first sexual intercourse differed according to marital status. Age and number of children ever born influenced modern contraceptive uptake among the never-married women, but religion and place of residence were associated with the probability of modern contraceptive uptake among ever-married women. PMID:26671948

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.

Gut transport characteristics in herbivorous and carnivorous serrasalmid fish from ion-poor Rio Negro water.

PubMed

Pelster, Bernd; Wood, Chris M; Speers-Roesch, Ben; Driedzic, William R; Almeida-Val, Vera; Val, Adalberto

2015-02-01

Three closely related characids, Tambaqui (omnivore), black Piranha (carnivore), and Pacu (herbivore), all Serrasalmidae, inhabit the ion-poor, acidic Rio Negro. We compared O2-consumption and N excretion rates in vivo, and sodium, chloride, glucose, and ammonia transport characteristics of gut sac preparations in vitro. The Pacu had a significantly higher weight-specific oxygen consumption, and a lower N/Q ratio than the omnivorous Tambaqui, and a significantly lower urea-N excretion rate than the carnivorous black Piranha, suggesting N-limitation in the herbivorous Pacu. With a value of 2.62 ± 0.15, gut to fork length ratio in the Pacu was about 2.5 times higher than in the black Piranha, and 2.0 times higher than in the Tambaqui. Anterior intestinal activities of three enzymes involved in N-fixation for amino acid synthesis (glutamate dehydrogenase, glutamate-oxaloacetate transferase, and glutamate-pyruvate transferase) were generally greatest in the carnivore and lowest in the herbivore species. In all three species, sodium, chloride, glucose, and ammonia were taken up at high rates from the intestine, resulting in an isosmotic fluid flux. Comparing the area-specific fluid flux of the anterior, mid, and posterior gut sections, no difference was detected between the three sections of the Pacu, while in the Tambaqui, it was highest in the anterior section, and in the black Piranha highest in the middle section. Overall, the area-specific uptake rates for sodium, chloride, glucose, and ammonia of anterior, mid, and posterior sections were similar in all three species, indicating that there is no difference in the area-specific transport rates associated with trophic position. The net ammonia uptake flux from gut interior was not significantly different from the net ammonia efflux to the serosal fluid, so that the ammonia removed from the intestine by the mucosal epithelium was quantitatively transferred through the tissue to the serosal side in all three species. Thus, metabolic activity of gut tissue did not significantly influence the net ammonia transfer. Due to the much higher gut to fork length ratio, the overall transport capacity of the gut of the herbivorous Pacu by far exceeded the transport capacity of their carnivorous and omnivorous relatives, thus compensating for the lower digestibility and the low Na(+), Cl(-), and N-content of the plant diet. Accordingly, in order to cope with the more difficult digestible plant material and the very low nitrogen content of plants, herbivorous fish have not evolved more effective area-specific transport capacities, but rather have increased the length of the gut.

Determinants of breast cancer screening uptake in Kurdish women of Iran.

PubMed

Aminisani, Nayyereh; Fattahpour, Roujin; Dastgiri, Saeed; Asghari-Jafarabadi, Mohammad; Allahverdipour, Hamid

2016-01-01

Recently, a national breast cancer screening program has been introduced in Iran.The aim of this study was to examine the determinants of breast cancer screening uptake among Kurdish women, in order to identify those characteristics that may be potentially associated with the screening uptake. Through a cross sectional study, in 2014, a random sample of 561 women aged 40 years and older without the history of breast cancer and identified with Kurdish background in Baneh county, Iran, were recruited and interviewed by two trained interviewers. Data were collected using a valid and reliable researcher made questionnaire. Univariate and multivariate logistic regression models with self-reported screening history as the dependent variable were used to estimate the odds ratios (ORs) with 95% of CI. The mean age of women was 43.64 (SD = 5.17). The participation rate in the mammography program was 16.8% (95% CI: 13.7-19.8%). The lowest level of participation was found among women aged 60 and older (OR = 0.30, 95% CI: 0.14-0.69), illiterate (OR = 0.63,95% CI: 0.40-0.99) and post-menopausal (OR = 0.56, 95% CI: 0.35-0.91) women. It was found that the level of breast screening uptake was low among Kurdish women compared to those reported in the previous studies. Designing participation enhancing interventions with a specific focus on older, illiterate and post-menopausal women are recommended.

Use of a dynamic simulation model to understand nitrogen cycling in the middle Rio Grande, NM.

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

Meixner, Tom; Tidwell, Vincent Carroll; Oelsner, Gretchen

2008-08-01

Water quality often limits the potential uses of scarce water resources in semiarid and arid regions. To best manage water quality one must understand the sources and sinks of both solutes and water to the river system. Nutrient concentration patterns can identify source and sink locations, but cannot always determine biotic processes that affect nutrient concentrations. Modeling tools can provide insight into these large-scale processes. To address questions about large-scale nitrogen removal in the Middle Rio Grande, NM, we created a system dynamics nitrate model using an existing integrated surface water--groundwater model of the region to evaluate our conceptual modelsmore » of uptake and denitrification as potential nitrate removal mechanisms. We modeled denitrification in groundwater as a first-order process dependent only on concentration and used a 5% denitrification rate. Uptake was assumed to be proportional to transpiration and was modeled as a percentage of the evapotranspiration calculated within the model multiplied by the nitrate concentration in the water being transpired. We modeled riparian uptake as 90% and agricultural uptake as 50% of the respective evapotranspiration rates. Using these removal rates, our model results suggest that riparian uptake, agricultural uptake and denitrification in groundwater are all needed to produce the observed nitrate concentrations in the groundwater, conveyance channels, and river as well as the seasonal concentration patterns. The model results indicate that a total of 497 metric tons of nitrate-N are removed from the Middle Rio Grande annually. Where river nitrate concentrations are low and there are no large nitrate sources, nitrate behaves nearly conservatively and riparian and agricultural uptake are the most important removal mechanisms. Downstream of a large wastewater nitrate source, denitrification and agricultural uptake were responsible for approximately 90% of the nitrogen removal.« less

Mechanisms by which moisture generates cocrystals.

PubMed

Jayasankar, Adivaraha; Good, David J; Rodríguez-Hornedo, Naír

2007-01-01

The purpose of this study is to determine the mechanisms by which moisture can generate cocrystals when solid particles of cocrystal reactants are exposed to deliquescent conditions (when moisture sorption forms an aqueous solution). It is based on the hypothesis that cocrystallization behavior during water uptake can be derived from solution chemistry using models that describe cocrystal solubility and reaction crystallization of molecular complexes. Cocrystal systems were selected with active pharmaceutical ingredients (APIs) that form hydrates and include carbamazepine, caffeine, and theophylline. Moisture uptake and crystallization behavior were studied by gravimetric vapor sorption, X-ray powder diffraction, and on-line Raman spectroscopy. Results indicate that moisture uptake generates cocrystals of carbamazepine-nicotinamide, carbamazepine-saccharin, and caffeine or theophylline with dicarboxylic acid ligands (oxalic acid, maleic acid, glutaric acid, and malonic acid) when solid mixtures with cocrystal reactants deliquesce. Microscopy studies revealed that the transformation mechanism to cocrystal involves (1) moisture uptake, (2) dissolution of reactants, and (3) cocrystal nucleation and growth. Studies of solid blends of reactants in a macro scale show that the rate and extent of cocrystal formation are a function of relative humidity, moisture uptake, deliquescent material, and dissolution rates of reactants. It is shown that the interplay between moisture uptake and dissolution determines the liquid phase composition, supersaturation, and cocrystal formation rates. Differences in the behavior of deliquescent additives (sucrose and fructose) are associated with moisture uptake and composition of the deliquesced solution. Our results show that deliquescence can transform API to cocrystal or reverse the reaction given the right conditions. Key indicators of cocrystal formation and stability are (1) moisture uptake, (2) cocrystal aqueous solubility, (3) solubility and dissolution of cocrystal reactants, and (4) transition concentration.

Effects of upland disturbance and instream restoration on hydrodynamics and ammonium uptake in headwater streams

USGS Publications Warehouse

Roberts, B.J.; Mulholland, P.J.; Houser, J.N.

2007-01-01

Delivery of water, sediments, nutrients, and organic matter to stream ecosystems is strongly influenced by the catchment of the stream and can be altered greatly by upland soil and vegetation disturbance. At the Fort Benning Military Installation (near Columbus, Georgia), spatial variability in intensity of military training results in a wide range of intensities of upland disturbance in stream catchments. A set of 8 streams in catchments spanning this upland disturbance gradient was selected for investigation of the impact of disturbance intensity on hydrodynamics and nutrient uptake. The size of transient storage zones and rates of NH4+ uptake in all study streams were among the lowest reported in the literature. Upland disturbance did not appear to influence stream hydrodynamics strongly, but it caused significant decreases in instream nutrient uptake. In October 2003, coarse woody debris (CWD) was added to 1/2 of the study streams (spanning the disturbance gradient) in an attempt to increase hydrodynamic and structural complexity, with the goals of enhancing biotic habitat and increasing nutrient uptake rates. CWD additions had positive short-term (within 1 mo) effects on hydrodynamic complexity (water velocity decreased and transient storage zone cross-sectional area, relative size of the transient storage zone, fraction of the median travel time attributable to transient storage over a standardized length of 200 m, and the hydraulic retention factor increased) and nutrient uptake (NH4+ uptake rates increased). Our results suggest that water quality in streams with intense upland disturbances can be improved by enhancing instream biotic nutrient uptake capacity through measures such as restoring stream CWD. ?? 2007 by The North American Benthological Society.

Balancing the competing requirements of air-breathing and display behaviour during male-male interactions in Siamese fighting fish Betta splendens.

PubMed

Alton, Lesley A; Portugal, Steven J; White, Craig R

2013-02-01

Air-breathing fish of the Anabantoidei group meet their metabolic requirements for oxygen through both aerial and aquatic gas exchange. Siamese fighting fish Betta splendens are anabantoids that frequently engage in aggressive male-male interactions which cause significant increases in metabolic rate and oxygen requirements. These interactions involve opercular flaring behaviour that is thought to limit aquatic oxygen uptake, and combines with the increase in metabolic rate to cause an increase in air-breathing behaviour. Air-breathing events interrupt display behaviour and increase risk of predation, raising the question of how Siamese fighting fish manage their oxygen requirements during agonistic encounters. Using open-flow respirometry, we measured rate of oxygen consumption in displaying fish to determine if males increase oxygen uptake per breath to minimise visits to the surface, or increase their reliance on aquatic oxygen uptake. We found that the increased oxygen requirements of Siamese fighting fish during display behaviour were met by increased oxygen uptake from the air with no significant changes in aquatic oxygen uptake. The increased aerial oxygen uptake was achieved almost entirely by an increase in air-breathing frequency. We conclude that limitations imposed by the reduced gill surface area of air-breathing fish restrict the ability of Siamese fighting fish to increase aquatic uptake, and limitations of the air-breathing organ of anabantoids largely restrict their capacity to increase oxygen uptake per breath. The resulting need to increase surfacing frequency during metabolically demanding agonistic encounters has presumably contributed to the evolution of the stereotyped surfacing behaviour seen during male-male interactions, during which one of the fish will lead the other to the surface, and each will take a breath of air. Copyright © 2012. Published by Elsevier Inc.

Diagnosis of Pediatric Hyperthyroidism: Technetium 99 Uptake Versus Thyroid Stimulating Immunoglobulins

PubMed Central

Misra, Madhusmita; Levitsky, Lynne L.

2015-01-01

Background: Treatment with antithyroid drugs is effective in conditions of increased thyroid hormone production (mostly Graves' Disease; GD), but not in subacute thyroiditis (SAT) or autoimmune thyroiditis (AIT). Positive thyroid stimulating immunoglobulins (TSI) make GD likely. However, not all children with GD have increased TSI. Uptake studies with 123I or 99Tc (99mTc) provide accurate and rapid diagnosis but are expensive and involve radiation exposure. Our objective was to compare TSI with 99mTc uptake for diagnosis of pediatric hyperthyroidism. Methods: We performed a retrospective chart review of hyperthyroid children who had both TSI estimation and 99mTc uptake assessment at presentation. Based on subsequent laboratory studies and follow-up, 37 had GD and 10 had non-GD thyroiditis. The TSI index was considered positive (TSI+) when it was above the upper limit of normal. 99mTc uptake was considered positive (Tc+) for any uptake >0.4% and negative (and low) (Tc-) for uptake ≤0.4%. Results: Forty-seven youth (83% females), aged 12.3±4.6 years, presented with a suppressed thyrotropin (TSH) and elevated free thyroxine and total triiodothyronine. All 37 patients with GD were Tc+ (100% sensitivity and specificity). The sensitivity of TSI for diagnosing GD was 84%, and the specificity was 100%. Six patients with GD were discordant with Tc+ but TSI–. Elevated TSI correlated with Tc+ (p=0.01) with a degree of agreement (kappa) of 0.69. Conclusion: 99mTc has excellent specificity and sensitivity in diagnosing GD. Given additional costs of 99mTc (two and a half times as much as TSI), it is reasonable to reserve 99mTc uptake assessment for hyperthyroidism of unclear etiology and negative TSI. PMID:25257665

Diagnosis of pediatric hyperthyroidism: technetium 99 uptake versus thyroid stimulating immunoglobulins.

PubMed

Baskaran, Charumathi; Misra, Madhusmita; Levitsky, Lynne L

2015-01-01

Treatment with antithyroid drugs is effective in conditions of increased thyroid hormone production (mostly Graves' Disease; GD), but not in subacute thyroiditis (SAT) or autoimmune thyroiditis (AIT). Positive thyroid stimulating immunoglobulins (TSI) make GD likely. However, not all children with GD have increased TSI. Uptake studies with (123)I or (99)Tc ((99m)Tc) provide accurate and rapid diagnosis but are expensive and involve radiation exposure. Our objective was to compare TSI with (99m)Tc uptake for diagnosis of pediatric hyperthyroidism. We performed a retrospective chart review of hyperthyroid children who had both TSI estimation and (99m)Tc uptake assessment at presentation. Based on subsequent laboratory studies and follow-up, 37 had GD and 10 had non-GD thyroiditis. The TSI index was considered positive (TSI+) when it was above the upper limit of normal. (99m)Tc uptake was considered positive (Tc+) for any uptake >0.4% and negative (and low) (Tc-) for uptake ≤0.4%. Forty-seven youth (83% females), aged 12.3±4.6 years, presented with a suppressed thyrotropin (TSH) and elevated free thyroxine and total triiodothyronine. All 37 patients with GD were Tc+ (100% sensitivity and specificity). The sensitivity of TSI for diagnosing GD was 84%, and the specificity was 100%. Six patients with GD were discordant with Tc+ but TSI-. Elevated TSI correlated with Tc+ (p=0.01) with a degree of agreement (kappa) of 0.69. (99m)Tc has excellent specificity and sensitivity in diagnosing GD. Given additional costs of (99m)Tc (two and a half times as much as TSI), it is reasonable to reserve (99m)Tc uptake assessment for hyperthyroidism of unclear etiology and negative TSI.

Transcriptomic Profiling and Physiological Responses of Halophyte Kochia sieversiana Provide Insights into Salt Tolerance

PubMed Central

Zhao, Long; Yang, Zongze; Guo, Qiaobing; Mao, Shun; Li, Shaoqiang; Sun, Fasheng; Wang, Huan; Yang, Chunwu

2017-01-01

Halophytes are remarkable plants that can tolerate extremely high-salinity conditions, and have different salinity tolerance mechanisms from those of glycophytic plants. In this work, we investigated the mechanisms of salinity tolerance of an extreme halophyte, Kochia sieversiana (Pall.) C. A. M, using RNA sequencing and physiological tests. The results showed that moderate salinity stimulated the growth and water uptake of K. sieversiana and, even under 480-mM salinity condition, K. sieversiana maintained an extremely high water content. This high water content may be a specific adaptive strategy of K. sieversiana to high salinity. The physiological analysis indicated that increasing succulence and great accumulations of sodium, alanine, sucrose, and maltose may be favorable to the water uptake and osmotic regulation of K. sieversiana under high-salinity stress. Transcriptome data indicated that some aquaporin genes and potassium (K+) transporter genes may be important for water uptake and ion balance, respectively, while different members of those gene families were employed under low- and high-salinity stresses. In addition, several aquaporin genes were up-regulated in low- but not high-salinity stressed roots. The highly expressed aquaporin genes may allow low-salinity stressed K. sieversiana plants to uptake more water than control plants. The leaf K+/root K+ ratio was enhanced under low- but not high-salinity stress, which suggested that low salinity might promote K+ transport from the roots to the shoots. Hence, we speculated that low salinity might allow K. sieversiana to uptake more water and transport more K+ from roots to shoots, increasing the growth rate of K. sieversiana. PMID:29225608

Kinetics and biodistribution in relation to tumour detection with 111In-labelled OV-TL 3 F(ab')2 in patients with ovarian cancer.

PubMed

Massuger, L F; Claessens, R A; Kenemans, P; Verheijen, R H; Boerman, O C; Meeuwis, A P; Schijf, C P; Buijs, W C; Hanselaar, T G; Corstens, F H

1991-07-01

The biological behaviour of 111In-labelled OV-TL 3 F(ab')2 was studied in 22 patients with suspected ovarian cancer. After i.v. injection with 140 MBq 111In-OV-TL 3 F(ab')2 (1 mg) blood samples were taken up to 96 h and urine and faeces were collected throughout the whole study. At surgery, 5 to 7 days post-injection, primary and metastatic tumour tissues, as well as fragments of several normal tissues, were removed and 111In uptake was measured. Blood activity disappeared with half-life values of 6.1 +/- 1.1 and 17.9 +/- 6.5 h. Within 96 h excretion in urine and faeces was 16.1 +/- 2.0% i.d. (mean +/- S.D.) and 3.1 +/- 1.9% i.d., respectively. Mean tissue uptake, expressed as % i.d. kg-1 was 3.9 +/- 1.0 for primary tumour, 11.5 +/- 5.0 for liver and 0.4 +/- 0.1 for several normal background tissues. Higher tumour uptake correlated with a higher detection rate at immunoscintigraphy. However, no strict correlation was found between the amount of tumour uptake and the expression of the monoclonal antibody defined OA3 antigen. Quantitation of organ activity, using region of interest analysis, resulted in mean peak organ activities for the liver of 16% i.d., spleen 9% i.d. and kidney 4% i.d. Distribution data indicate that besides specific antibody-antigen interaction several other mechanisms play a role in uptake in tumour and other tissues.

Combined Effect of Cameo2 and CBP on the Cellular Uptake of Lutein in the Silkworm, Bombyx mori

PubMed Central

Dong, Xiao-Long; Chai, Chun-Li; Pan, Cai-Xia; Tang, Hui; Chen, Yan-Hong; Dai, Fang-Yin; Pan, Min-Hui; Lu, Cheng

2014-01-01

Formation of yellow-red color cocoons in the silkworm, Bombyx mori, occurs as the result of the selective delivery of carotenoids from the midgut to the silk gland via the hemolymph. This process of pigment transport is thought to be mediated by specific cellular carotenoids carrier proteins. Previous studies indicated that two proteins, Cameo2 and CBP, are associated with the selective transport of lutein from the midgut into the silk gland in Bombyx mori. However, the exact roles of Cameo2 and CBP during the uptake and transport of carotenoids are still unknown. In this study, we investigated the respective contributions of these two proteins to lutein and β-carotene transport in Bombyx mori as well as commercial cell-line. We found that tissues, expressed both Cameo2 and CBP, accumulate lutein. Cells, co-expressed Cameo2 and CBP, absorb 2 fold more lutein (P<0.01) than any other transfected cells, and the rate of cellular uptake of lutein was concentration-dependent and reached saturation. From immunofluorescence staining, confocal microscopy observation and western blot analysis, Cameo2 was localized at the membrane and CBP was expressed in the cytosol. What’s more, bimolecular fluorescence complementation analysis showed that these two proteins directly interacted at cellular level. Therefore, Cameo2 and CBP are necessarily expressed in midguts and silk glands for lutein uptake in Bombyx mori. Cameo2 and CBP, as the membrane protein and the cytosol protein, respectively, have the combined effect to facilitate the cellular uptake of lutein. PMID:24475153

Does elevated CO 2 alter silica uptake in trees?

DOE PAGES

Fulweiler, Robinson W.; Maguire, Timothy J.; Carey, Joanna C.; ...

2015-01-13

Human activities have greatly altered global carbon (C) and Nitrogen (N) cycling. In fact, atmospheric concentrations of carbon dioxide (CO 2) have increased 40% over the last century and the amount of N cycling in the biosphere has more than doubled. In an effort to understand how plants will respond to continued global CO 2 fertilization, longterm free-air CO 2 enrichment experiments have been conducted at sites around the globe. Here we examine how atmospheric CO 2 enrichment and N fertilization affects the uptake of silicon (Si) in the Duke Forest, North Carolina, a stand dominated by Pinus taeda (loblollymore » pine), and five hardwood species. Specifically, we measured foliar biogenic silica concentrations in five deciduous and one coniferous species across three treatments: CO 2 enrichment, N enrichment, and N and CO 2 enrichment. We found no consistent trends in foliar Si concentration under elevated CO 2, N fertilization, or combined elevated CO 2 and N fertilization. However, two-thirds of the tree species studied here have Si foliar concentrations greater than well-known Si accumulators, such as grasses. Based on net primary production values and aboveground Si concentrations in these trees, we calculated forest Si uptake rates under control and elevated CO 2 concentrations. Due largely to increased primary production, elevated CO 2 enhanced the magnitude of Si uptake between 20 and 26%, likely intensifying the terrestrial silica pump. This uptake of Si by forests has important implications for Si export from terrestrial systems, with the potential to impact C sequestration and higher trophic levels in downstream ecosystems.« less

Clearance and organ localization of particles and soluble complexes in mice with circulating complexes.

PubMed Central

Carter, S D; Brennan, F M; Grace, S A; Elson, C J

1984-01-01

The clearance and organ localization of a number of substances cleared by either Fc-dependent or -independent mechanisms was studied in normal mice and in mice with endogenously produced persistent circulating complexes. Clearance of covalent dimers of mouse IgG, chicken IgG and ovalbumin were no different between the two groups of mice. By contrast, hepatic and splenic uptake of dimeric mouse IgG (but not of chicken IgG or ovalbumin dimer) was impaired in the mice with persisting complexes. Surprisingly the rate of clearance of sheep red blood cells (SRBC) was increased in mice with persisting complexes as was hepatic uptake of polyvinyl pyrrolidone. It is suggested that the mononuclear phagocytes of mice with persistent circulating complexes are non-specifically stimulated while their ability to take up soluble complexes by Fc-dependent attachment is selectively impaired. PMID:6746002

Influence of CeO{sub 2} NPs on biological phosphorus removal and bacterial community shifts in a sequencing batch biofilm reactor with the differential effects of molecular oxygen

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

Xu, Yi; Wang, Chao

2016-11-15

The effects of CeO{sub 2} nanoparticles (CeO{sub 2} NPs) on a sequencing batch biofilm reactor (SBBR) with established biological phosphorus (P) removal were investigated from the processes of anaerobic P release and aerobic P uptake. At low concentration (0.1 mg/L), no significant impact was observed on total phosphorus (TP) removal after operating for 8 h. However, at a concentration of 20 mg/L, TP removal efficiency decreased from 83.68% to 55.88% and 16.76% when the CeO{sub 2} NPs were added at the beginning of the anaerobic and aerobic periods, respectively. Further studies illustrated that the inhibition of the specific P releasemore » rate was caused by the reversible states of Ce{sup 3+} and Ce{sup 4+}, which inhibited the activity of exopolyphosphatase (PPX) and transformation of poly-β-hydoxyalkanoates (PHA) and glycogen, as well as the uptake of volatile fatty acids (VFAs). The decrease in the specific P uptake rate was mainly attributed to the significantly suppressed energy generation and decreased abundance of Burkholderia caused by excess reactive oxygen species. The removal of chemical oxygen demand (COD) was not influenced by CeO{sub 2} NPs under aerobic conditions, due to the increased abundance of Acetobacter and Acidocella after exposure. The inhibitory effects of CeO{sub 2} NPs with molecular oxygen were reduced after anaerobic exposure due to the enhanced particle size and the presence of Ce{sup 3+}. - Highlights: • CeO{sub 2} NPs (20 mg/L) had a notable toxicity effect on P removal in SBBR system. • The deteriorated SPRR was caused by the inhibited key enzyme activity (PPX). • The decreased SPUR was caused by the bacterial community shifts. • Ce ions converting and excess ROS generation are related toxicity mechanisms.« less

Health behaviour modelling for prenatal diagnosis in Australia: a geodemographic framework for health service utilisation and policy development

PubMed Central

Muggli, Evelyne E; McCloskey, David; Halliday, Jane L

2006-01-01

Background Despite the wide availability of prenatal screening and diagnosis, a number of studies have reported no decrease in the rate of babies born with Down syndrome. The objective of this study was to investigate the geodemographic characteristics of women who have prenatal diagnosis in Victoria, Australia, by applying a novel consumer behaviour modelling technique in the analysis of health data. Methods A descriptive analysis of data on all prenatal diagnostic tests, births (1998 and 2002) and births of babies with Down syndrome (1998 to 2002) was undertaken using a Geographic Information System and socioeconomic lifestyle segmentation classifications. Results Most metropolitan women in Victoria have average or above State average levels of uptake of prenatal diagnosis. Inner city women residing in high socioeconomic lifestyle segments who have high rates of prenatal diagnosis spend 20% more on specialist physician's fees when compared to those whose rates are average. Rates of prenatal diagnosis are generally low amongst women in rural Victoria, with the lowest rates observed in farming districts. Reasons for this are likely to be a combination of lack of access to services (remoteness) and individual opportunity (lack of transportation, low levels of support and income). However, there are additional reasons for low uptake rates in farming areas that could not be explained by the behaviour modelling. These may relate to women's attitudes and choices. Conclusion A lack of statewide geodemographic consistency in uptake of prenatal diagnosis implies that there is a need to target health professionals and pregnant women in specific areas to ensure there is increased equity of access to services and that all pregnant women can make informed choices that are best for them. Equally as important is appropriate health service provision for families of children with Down syndrome. Our findings show that these potential interventions are particularly relevant in rural areas. Classifying data to lifestyle segments allowed for practical comparisons of the geodemographic characteristics of women having prenatal diagnosis in Australia at a population level. This methodology may in future be a feasible and cost-effective tool for service planners and policy developers. PMID:16945156

Low rate loading-induced convection enhances net transport into the intervertebral disc in vivo.

PubMed

Gullbrand, Sarah E; Peterson, Joshua; Mastropolo, Rosemarie; Roberts, Timothy T; Lawrence, James P; Glennon, Joseph C; DiRisio, Darryl J; Ledet, Eric H

2015-05-01

The intervertebral disc primarily relies on trans-endplate diffusion for the uptake of nutrients and the clearance of byproducts. In degenerative discs, diffusion is often diminished by endplate sclerosis and reduced proteoglycan content. Mechanical loading-induced convection has the potential to augment diffusion and enhance net transport into the disc. The ability of convection to augment disc transport is controversial and has not been demonstrated in vivo. To determine if loading-induced convection can enhance small molecule transport into the intervertebral disc in vivo. Net transport was quantified via postcontrast enhanced magnetic resonance imaging (MRI) into the discs of the New Zealand white rabbit lumbar spine subjected to in vivo cyclic low rate loading. Animals were administered the MRI contrast agent gadodiamide intravenously and subjected to in vivo low rate loading (0.5 Hz, 200 N) via a custom external loading apparatus for either 2.5, 5, 10, 15, or 20 minutes. Animals were then euthanized and the lumbar spines imaged using postcontrast enhanced MRI. The T1 constants in the nucleus, annulus, and cartilage endplates were quantified as a measure of gadodiamide transport into the loaded discs compared with the adjacent unloaded discs. Microcomputed tomography was used to quantify subchondral bone density. Low rate loading caused the rapid uptake and clearance of gadodiamide in the nucleus compared with unloaded discs, which exhibited a slower rate of uptake. Relative to unloaded discs, low rate loading caused a maximum increase in transport into the nucleus of 16.8% after 5 minutes of loading. Low rate loading increased the concentration of gadodiamide in the cartilage endplates at each time point compared with unloaded levels. Results from this study indicate that forced convection accelerated small molecule uptake and clearance in the disc induced by low rate mechanical loading. Low rate loading may, therefore, be therapeutic to the disc as it may enhance the nutrient uptake and waste product clearance. Copyright © 2015 Elsevier Inc. All rights reserved.

Hydroxyl/bile acid exchange. A new mechanism for the uphill transport of cholate by basolateral liver plasma membrane vesicles.

PubMed

Blitzer, B L; Terzakis, C; Scott, K A

1986-09-15

In order to characterize the driving forces for the concentrative uptake of unconjugated bile acids by the hepatocyte, the effects of pH gradients on the uptake of [3H]cholate by rat basolateral liver plasma membrane vesicles were studied. In the presence of an outwardly directed hydroxyl gradient (pH 6.0 outside and pH 7.5 inside the vesicle), cholate uptake was markedly stimulated and the bile acid was transiently accumulated at a concentration 1.5- to 2-fold higher than at equilibrium ("overshoot"). In the absence of a pH gradient (pH 6.0 or 7.5 both inside and outside the vesicle), uptake was relatively slower and no overshoot was seen. Reductions in the magnitude of the transmembrane pH gradient were associated with slower initial uptake rates and smaller overshoots. Cholate uptake under pH gradient conditions was inhibited by furosemide and bumetanide but not by 4, 4'-diisothiocyano-2,2'-disulfonic stilbene (SITS), 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (DIDS), or probenecid. In the absence of a pH gradient, an inside-positive valinomycin-induced K+ diffusion potential caused a slight increase in cholate uptake which was insensitive to furosemide. Moreover, in the presence of an outwardly directed hydroxyl gradient, uphill cholate transport was observed even under voltage clamped conditions. These findings suggest that pH gradient-driven cholate uptake was not due to associated electrical potentials. Despite an identical pKa to that of cholate, an outwardly directed hydroxyl gradient did not drive uphill transport of three other unconjugated bile acids (deoxycholate, chenodeoxycholate, ursodeoxycholate), suggesting that a non-ionic diffusion mechanism cannot account for uphill cholate transport. In canalicular vesicles, although cholate uptake was relatively faster in the presence of a pH gradient than in the absence of a gradient, peak uptake was only slightly above that found at equilibrium under voltage clamped conditions. These findings suggest a specific carrier on the basolateral membrane of the hepatocyte which mediates hydroxyl/cholate exchange (or H+-cholate co-transport). A model for uphill cholate transport is discussed in which the Na+ pump would ultimately drive Na+/H+ exchange which in turn would drive hydroxyl/cholate exchange.

Protein/oligonucleotide conjugates as a cell specific PNA carrier.

PubMed

Obara, K; Ishihara, T; Akaike, T; Maruyama, A

2001-01-01

We have focused on proteineus ligand conjugate with oligonucleotides (ODNs) as a cell-specific delivery vector for peptide nucleic acids (PNAs). Asialofetuin (AF), a hepatocyte-specific proteineus ligand, was conjugated with ODNs that served as binding sites for PNAs. Succinimidyl-transe-4(N-maleimidylmethyl)-cyclohexane-1-carboxylate (SMCC) modified AF was coupled with 5'-thiolated oligodeoxynucleotide (HS-ODN). The resulting conjugate held PNAs with sequence-specific manner. The PNA/DNA conjugate complex has resistance against nucleases in serum. The efficient release of PNA from the complex was observed when the complex was made in contact with a target nucleotide. PNA uptake to hepatocytes was greatly enhanced when hepatocytes was incubated with PNA/conjugate complex. Free AF thoroughly inhibited PNA uptake with the conjugate, evidencing asialoglycoprotein receptor (ASGP-R) mediated endocytosis to be a major-route for the cellular uptake.

Nitrate removal in stream ecosystems measured by 15N addition experiments: Denitrification

USGS Publications Warehouse

Mulholland, P.J.; Hall, R.O.; Sobota, D.J.; Dodds, W.K.; Findlay, S.E.G.; Grimm, N. B.; Hamilton, S.K.; McDowell, W.H.; O'Brien, J. M.; Tank, J.L.; Ashkenas, L.R.; Cooper, L.W.; Dahm, Clifford N.; Gregory, S.V.; Johnson, S.L.; Meyer, J.L.; Peterson, B.J.; Poole, G.C.; Valett, H.M.; Webster, J.R.; Arango, C.P.; Beaulieu, J.J.; Bernot, M.J.; Burgin, A.J.; Crenshaw, C.L.; Helton, A.M.; Johnson, L.T.; Niederlehner, B.R.; Potter, J.D.; Sheibley, R.W.; Thomasn, S.M.

2009-01-01

We measured denitrification rates using a field 15N-NO- 3 tracer-addition approach in a large, cross-site study of nitrate uptake in reference, agricultural, and suburban-urban streams. We measured denitrification rates in 49 of 72 streams studied. Uptake length due to denitrification (SWden) ranged from 89 m to 184 km (median of 9050 m) and there were no significant differences among regions or land-use categories, likely because of the wide range of conditions within each region and land use. N2 production rates far exceeded N2O production rates in all streams. The fraction of total NO-3 removal from water due to denitrification ranged from 0.5% to 100% among streams (median of 16%), and was related to NHz 4 concentration and ecosystem respiration rate (ER). Multivariate approaches showed that the most important factors controlling SWden were specific discharge (discharge / width) and NO-3 concentration (positive effects), and ER and transient storage zones (negative effects). The relationship between areal denitrification rate (Uden) and NO- 3 concentration indicated a partial saturation effect. A power function with an exponent of 0.5 described this relationship better than a Michaelis-Menten equation. Although Uden increased with increasing NO- 3 concentration, the efficiency of NO-3 removal from water via denitrification declined, resulting in a smaller proportion of streamwater NO-3 load removed over a given length of stream. Regional differences in stream denitrification rates were small relative to the proximate factors of NO-3 concentration and ecosystem respiration rate, and land use was an important but indirect control on denitrification in streams, primarily via its effect on NO-3 concentration. ?? 2009.

UPTAKE AND ELIMINATION OF IONIZABLE ORGANIC CHEMICALS AT FISH GILLS: PART I. MODEL FORMULATION, PARAMETERIZATION, AND BEHAVIOR

EPA Science Inventory

Effects of pH and alkalinity on uptake and elimination of ionizable organic chemicals at the gills of large rainbow trout were studied. Increased pH reduced uptake rates of weakly-acidic chlorinated phenols and increased that of weakly-basic 3,4-dichlorobenzylamine, indicating gr...

Optimum aerobic volume control based on continuous in-line oxygen uptake monitoring.

PubMed

Svardal, K; Lindtner, S; Winkler, S

2003-01-01

Dynamic adaptation of the aerated volume to changing load conditions is essential to maximise the nitrogen removal performance and to minimise energy consumption. A control strategy is presented which provides optimum aerobic volume control (OAV-control concept) based on continuous in-line oxygen uptake monitoring. For ammonium concentrations below 1 mg/l the oxygen uptake rate shows a strong and almost linear dependency on the ammonium concentration. Therefore, the oxygen uptake rate is an ideal indicator for the nitrification performance in activated sludge systems. The OAV-control concept provides dynamic variation of the minimum aerobic volume required for complete nitrification and therefore maximises the denitrification performance. In-line oxygen uptake monitoring is carried out by controlling the oxygen concentration in a continuous aerated zone of the aeration tank and measuring the total air flow to the aeration tank. The total air flow to the aeration tank is directly proportional to the current oxygen uptake rate and can therefore be used as an indicator for the required aerobic volume. The instrumentation requirements for installation of the OAV-control are relatively low, oxygen sensors in the aeration tank and an on-line air flow measurement are needed. This enables individual control of aeration tanks operated in parallel at low investment costs. The OAV-control concept is installed at the WWTP Linz-Asten (1 Mio PE) and shows very good results. Full scale results are presented.

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.

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

LAS bioconcentration is isomer specific

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

Tolls, J.; Haller, M.; Graaf, I. de

1995-12-31

The authors measured parent compound specific bioconcentration data for linear alkylbenzene sulfonates in Pimephales promelas. They did so by using cold, custom synthesized sulfophenyl alkanes. They observed that, within homologous series of isomers, the uptake rate constants (k{sub 1}) and the bioconcentration factor (BCF) increase with increasing number of carbon atoms in the alkyl chain (n{sub C-atoms}). In contrast, the elimination rate constant k{sub 2} appears to be independent of the alkyl chain length. Regressions of log BCF vs n{sub C-atoms} yielded different slopes for the homologous groups of the 5- and the 2-sulfophenyl alkane isomers. Regression of all logmore » BCF-data vs log 1/CMC yielded a good description of the data. However, when regressing the data for both homologous series separately again very different slopes are obtained. The results therefore indicate that hydrophobicity-bioconcentration relationships may be different for different homologous groups of sulfophenyl alkanes.« less

Evaluating the Efficacy of GLUT Inhibitors Using a Seahorse Extracellular Flux Analyzer.

PubMed

Wei, Changyong; Heitmeier, Monique; Hruz, Paul W; Shanmugam, Mala

2018-01-01

Glucose is metabolized through anaerobic glycolysis and aerobic oxidative phosphorylation (OXPHOS). Perturbing glucose uptake and its subsequent metabolism can alter both glycolytic and OXPHOS pathways and consequently lactate and/or oxygen consumption. Production and secretion of lactate, as a consequence of glycolysis, leads to acidification of the extracellular medium. Molecular oxygen is the final electron acceptor in the electron transport chain, facilitating oxidative phosphorylation of ADP to ATP. The alterations in extracellular acidification and/or oxygen consumption can thus be used as indirect readouts of glucose metabolism and assessing the impact of inhibiting glucose transport through specific glucose transporters (GLUTs). The Seahorse bioenergetics analyzer can measure both the oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). The proposed methodology affords a robust, high-throughput method to screen for GLUT inhibition in cells engineered to express specific GLUTs, providing live cell read-outs upon GLUT inhibition.

Irrigation frequency alters nutrient uptake in container-grown Rhododendron plants grown with different rates of nitrogen

USDA-ARS?s Scientific Manuscript database

The influence of irrigation frequency (same amount of water per day given at different times) on nutrient uptake of container-grown evergreen Rhododendron ‘P.J.M. Compact’ (PJM) and ‘English Roseum’ (ER) and deciduous Rhododendron ‘Gibraltar’ (AZ) grown with different rates of nitrogen (N) fertilize...

Body acceleration distribution and O2 uptake in humans during running and jumping

NASA Technical Reports Server (NTRS)

Bhattacharya, A.; Mccutcheon, E. P.; Shvartz, E.; Greenleaf, J. E.

1980-01-01

The distribution of body acceleration and associated oxygen uptake and heart rate responses are investigated in treadmill running and trampoline jumping. Accelerations in the +Gz direction were measured at the lateral ankle, lumbosacral region and forehead of eight young men during level treadmill walking and running at four speeds and trampoline jumping at four heights, together with corresponding oxygen uptake and heart rate. With increasing treadmill speed, peak acceleration at the ankle is found always to exceed that at the back and forehead, and acceleration profiles with higher frequency components than those observed during jumping are observed. Acceleration levels are found to be more uniformly distributed with increasing height in jumping, although comparable oxygen uptake and heat rates are obtained. Results indicate that the magnitude of the biomechanical stimuli is greater in trampoline jumping than in running, which finding could be of use in the design of procedures to avert deconditioning in persons exposed to weightlessness.

Rotenone-sensitive mitochondrial potential in Phytomonas serpens: electrophoretic Ca(2+) accumulation.

PubMed

Moysés, Danuza Nogueira; Barrabin, Hector

2004-06-07

Phytomonas sp. are flagellated trypanosomatid plant parasites that cause diseases of economic importance in plantations of coffee, oil palm, cassava and coconuts. Here we investigated Ca(2+) uptake by the vanadate-insensitive compartments using permeabilized Phytomonas serpens promastigotes. This uptake occurs at a rate of 1.13+/-0.23 nmol Ca(2+) mg x protein(-1) min(-1). It is completely abolished by the H(+) ionophore FCCP and by valinomycin and nigericin. It is also inhibited by 2 microM ruthenium red, which, at this low concentration, is known to inhibit the mitochondrial calcium uniport. Furthermore, salicylhydroxamic acid (SHAM) and propylgallate, specific inhibitors of the alternative oxidase in plant and parasite mitochondria, are also effective as inhibitors of the Ca(2+) transport. These compounds abolish the membrane potential that is monitored with safranine O. Rotenone, an inhibitor of NADH-CoQ oxidoreductase, can also dissipate 100% of the membrane potential. It is suggested that the mitochondria of P. serpens can be energized via oxidation of NADH in a pathway involving the NADH-CoQ oxidoreductase and the alternative oxidase to regenerate the ubiquinone. The electrochemical H(+) gradient can be used to promote Ca(2+) uptake by the mitochondria.

Fatty acid uptake by isolated rat heart myocytes represents a carrier-mediated transport process.

PubMed Central

Stremmel, W

1988-01-01

The mechanism by which fatty acids enter cardiomyocytes is unclear. Therefore, the influx kinetics of [3H]oleate into isolated rat heart myocytes were examined. Cells were incubated at 37 degrees C with [3H]oleate bound to albumin in various molar ratios and the initial rate of uptake (V0) was determined as a function of the unbound oleate concentration in the medium. V0 was saturable with increasing oleate concentrations incubated (Km 78 nM; Vmax 1.9 nmol X min-1 per 10(6) cells) and temperature dependent with an optimum at 37 degrees C. Furthermore, binding of [3H]oleate to isolated plasma membranes of cardiomyocytes was saturable, revealing a KD of 42 nM, and was inhibited by heat denaturation or trypsin pretreatment of the membranes. From these membranes a single 40-kD protein with high affinity for a variety of long chain fatty acids was isolated. With a monospecific antibody to this membrane protein, binding as well as cellular influx of [3H]oleate was selectively inhibited. These data indicate that at least a portion of myocardial fatty acid uptake is mediated by a specific membrane protein. Images PMID:3343344

Positron emission tomography with α-[11C]methyl-L-tryptophan in tuberous sclerosis complex-related epilepsy.

PubMed

Rubí, Sebastià; Costes, Nicolas; Heckemann, Rolf A; Bouvard, Sandrine; Hammers, Alexander; Martí Fuster, Berta; Ostrowsky, Karine; Montavont, Alexandra; Jung, Julien; Setoain, Xavier; Catenoix, Hélène; Hino, Keiko; Liger, François; Le Bars, Didier; Ryvlin, Philippe

2013-12-01

Tuberous sclerosis complex (TSC) is often associated with cerebral tubers and medically intractable epilepsy. We reevaluated whether increased uptake of α-[(11) C]methyl-l-tryptophan (AMT) in cerebral tubers is associated with tuber epileptogenicity. We included 12 patients (six male, 4-53 years old) with TSC and refractory seizures who were evaluated for epilepsy surgery in our center, including video-electroencephalographic (EEG) monitoring, fluid-attenuated inversion recovery magnetic resonance imaging (FLAIR MRI), and positron emission tomography (PET) with α-[(11) C]methyl-l-tryptophan (AMT-PET). Nine of these 12 patients also underwent intracerebral EEG recording. AMT uptake in each tuber was visually evaluated on PET coregistered with MRI. An AMT uptake index based on lesional/healthy cortex ratio was also calculated. Sensitivity and specificity values of AMT-PET in the detection of epileptogenic lesions were obtained, using the available electroclinical and neuroimaging evidence as the gold standard for epileptogenicity. A total of 126 tubers were identified. Two of 12 patients demonstrated a tuber with clearly increased AMT uptake, one of whom also showed a subtle increased AMT uptake in another contralateral tuber. Four other patients showed only subtle increased AMT uptake. The only two tubers with clearly increased AMT uptake proved to be epileptogenic based on intracerebral EEG data, whereas none of the tubers associated with subtle increased AMT uptake were involved at ictal onset. In a per-patient approach, this yielded a sensitivity of clearly increased AMT uptake in detecting tuber epileptogenicity of 17% (2/12 patients), whereas the per-lesion sensitivity and specificity were 12% (95% confidence interval [CI]: 3-34%) and 100% (95% CI: 97-100%), respectively. AMT-PET is a specific neuroimaging technique in the identification of epileptogenic tubers in TSC. Despite its low sensitivity, the clinical usefulness of AMT-PET still deserves to be considered according to the challenging complexity of epilepsy surgery in tuberous sclerosis. Wiley Periodicals, Inc. © 2013 International League Against Epilepsy.

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.

Kinetic Modelling of Infection Tracers [18F]FDG, [68Ga]Ga-Citrate, [11C]Methionine, and [11C]Donepezil in a Porcine Osteomyelitis Model.

PubMed

Jødal, Lars; Jensen, Svend B; Nielsen, Ole L; Afzelius, Pia; Borghammer, Per; Alstrup, Aage K O; Hansen, Søren B

2017-01-01

Positron emission tomography (PET) is increasingly applied for infection imaging using [ 18 F]FDG as tracer, but uptake is unspecific. The present study compares the kinetics of [ 18 F]FDG and three other PET tracers with relevance for infection imaging. A juvenile porcine osteomyelitis model was used. Eleven pigs underwent PET/CT with 60-minute dynamic PET imaging of [ 18 F]FDG, [ 68 Ga]Ga-citrate, [ 11 C]methionine, and/or [ 11 C]donepezil, along with blood sampling. For infectious lesions, kinetic modelling with one- and two-tissue-compartment models was conducted for each tracer. Irreversible uptake was found for [ 18 F]FDG and [ 68 Ga]Ga-citrate; reversible uptake was found for [ 11 C]methionine (two-tissue model) and [ 11 C]donepezil (one-tissue model). The uptake rate for [ 68 Ga]Ga-citrate was slow and diffusion-limited. For the other tracers, the uptake rate was primarily determined by perfusion (flow-limited uptake). Net uptake rate for [ 18 F]FDG and distribution volume for [ 11 C]methionine were significantly higher for infectious lesions than for correspondingly noninfected tissue. For [ 11 C]donepezil in pigs, labelled metabolite products appeared to be important for the analysis. The kinetics of the four studied tracers in infection was characterized. For clinical applications, [ 18 F]FDG remains the first-choice PET tracer. [ 11 C]methionine may have a potential for detecting soft tissue infections. [ 68 Ga]Ga-citrate and [ 11 C]donepezil were not found useful for imaging of osteomyelitis.

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.

Tracking intracellular uptake and localisation of alkyne tagged fatty acids using Raman spectroscopy

NASA Astrophysics Data System (ADS)

Jamieson, Lauren E.; Greaves, Jennifer; McLellan, Jayde A.; Munro, Kevin R.; Tomkinson, Nicholas C. O.; Chamberlain, Luke H.; Faulds, Karen; Graham, Duncan

2018-05-01

Intracellular uptake, distribution and metabolism of lipids are tightly regulated characteristics in healthy cells. An analytical technique capable of understanding these characteristics with a high level of species specificity in a minimally invasive manner is highly desirable in order to understand better how these become disrupted during disease. In this study, the uptake and distribution of three different alkyne tagged fatty acids in single cells were monitored and compared, highlighting the ability of Raman spectroscopy combined with alkyne tags for better understanding of the fine details with regard to uptake, distribution and metabolism of very chemically specific lipid species. This indicates the promise of using Raman spectroscopy directly with alkyne tagged lipids for cellular studies as opposed to subsequently clicking of a fluorophore onto the alkyne for fluorescence imaging.

Cadmium uptake and xylem loading are active processes in the hyperaccumulator Sedum alfredii.

PubMed

Lu, Ling-li; Tian, Sheng-ke; Yang, Xiao-e; Li, Ting-qiang; He, Zhen-li

2009-04-01

Sedum alfredii is a well known cadmium (Cd) hyperaccumulator native to China; however, the mechanism behind its hyperaccumulation of Cd is not fully understood. Through several hydroponic experiments, characteristics of Cd uptake and translocation were investigated in the hyperaccumulating ecotype (HE) of S. alfredii in comparison with its non-hyperaccumulating ecotype (NHE). The results showed that at Cd level of 10 microM measured Cd uptake in HE was 3-4 times higher than the implied Cd uptake calculated from transpiration rate. Furthermore, inhibition of transpiration rate in the HE has no essential effect on Cd accumulation in shoots of the plants. Low temperature treatment (4 degrees C) significantly inhibited Cd uptake and reduced upward translocation of Cd to shoots for 9 times in HE plants, whereas no such effect was observed in NHE. Cadmium concentration was 3-4-fold higher in xylem sap of HE, as compared with that in external uptake solution, whereas opposite results were obtained for NHE. Cadmium concentration in xylem sap of HE was significantly reduced by the addition of metabolic inhibitors, carbonyl cyanide m-chlorophenylhydrazone (CCCP) and 2,4-dinitrophenol (DNP), in the uptake solutions, whereas no such effect was noted in NHE. These results suggest that Cd uptake and translocation is an active process in plants of HE S. alfredii, symplastic pathway rather than apoplastic bypass contributes greatly to root uptake, xylem loading and translocation of Cd to the shoots of HE, in comparison with the NHE plants.

Toxicokinetics/toxicodynamics links bioavailability for assessing arsenic uptake and toxicity in three aquaculture species.

PubMed

Chen, Wei-Yu; Liao, Chung-Min

2012-11-01

The purpose of this study was to link toxicokinetics/toxicodynamics (TK/TD) and bioavailability-based metal uptake kinetics to assess arsenic (As) uptake and bioaccumulation in three common farmed species of tilapia (Oreochromis mossambicus), milkfish (Chanos chanos), and freshwater clam (Corbicula fluminea). We developed a mechanistic framework by linking damage assessment model (DAM) and bioavailability-based Michaelis-Menten model for describing TK/TD and As uptake mechanisms. The proposed model was verified with published acute toxicity data. The estimated TK/TD parameters were used to simulate the relationship between bioavailable As uptake and susceptibility probability. The As toxicity was also evaluated based on a constructed elimination-recovery scheme. Absorption rate constants were estimated to be 0.025, 0.016, and 0.175 mL g(-1) h(-1) and As uptake rate constant estimates were 22.875, 63.125, and 788.318 ng g(-1) h(-1) for tilapia, milkfish, and freshwater clam, respectively. Here we showed that a potential trade-off between capacities of As elimination and damage recovery was found among three farmed species. Moreover, the susceptibility probability can also be estimated by the elimination-recovery relations. This study suggested that bioavailability-based uptake kinetics and TK/TD-based DAM could be integrated for assessing metal uptake and toxicity in aquatic organisms. This study is useful to quantitatively assess the complex environmental behavior of metal uptake and implicate to risk assessment of metals in aquaculture systems.

Preclinical PET imaging of EGFR levels: pairing a targeting with a non-targeting Sel-tagged Affibody-based tracer to estimate the specific uptake.

PubMed

Cheng, Qing; Wållberg, Helena; Grafström, Jonas; Lu, Li; Thorell, Jan-Olov; Hägg Olofsson, Maria; Linder, Stig; Johansson, Katarina; Tegnebratt, Tetyana; Arnér, Elias S J; Stone-Elander, Sharon; Ahlzén, Hanna-Stina Martinsson; Ståhl, Stefan

2016-12-01

Though overexpression of epidermal growth factor receptor (EGFR) in several forms of cancer is considered to be an important prognostic biomarker related to poor prognosis, clear correlations between biomarker assays and patient management have been difficult to establish. Here, we utilize a targeting directly followed by a non-targeting tracer-based positron emission tomography (PET) method to examine some of the aspects of determining specific EGFR binding in tumors. The EGFR-binding Affibody molecule ZEGFR:2377 and its size-matched non-binding control ZTaq:3638 were recombinantly fused with a C-terminal selenocysteine-containing Sel-tag (ZEGFR:2377-ST and ZTaq:3638-ST). The proteins were site-specifically labeled with DyLight488 for flow cytometry and ex vivo tissue analyses or with (11)C for in vivo PET studies. Kinetic scans with the (11)C-labeled proteins were performed in healthy mice and in mice bearing xenografts from human FaDu (squamous cell carcinoma) and A431 (epidermoid carcinoma) cell lines. Changes in tracer uptake in A431 xenografts over time were also monitored, followed by ex vivo proximity ligation assays (PLA) of EGFR expressions. Flow cytometry and ex vivo tissue analyses confirmed EGFR targeting by ZEGFR:2377-ST-DyLight488. [Methyl-(11)C]-labeled ZEGFR:2377-ST-CH3 and ZTaq:3638-ST-CH3 showed similar distributions in vivo, except for notably higher concentrations of the former in particularly the liver and the blood. [Methyl-(11)C]-ZEGFR:2377-ST-CH3 successfully visualized FaDu and A431 xenografts with moderate and high EGFR expression levels, respectively. However, in FaDu tumors, the non-specific uptake was large and sometimes equally large, illustrating the importance of proper controls. In the A431 group observed longitudinally, non-specific uptake remained at same level over the observation period. Specific uptake increased with tumor size, but changes varied widely over time in individual tumors. Total (membranous and cytoplasmic) EGFR in excised sections increased with tumor growth. There was no positive correlation between total EGFR and specific tracer uptake, which, since ZEGFR:2377 binds extracellularly and is slowly internalized, indicates a discordance between available membranous and total EGFR expression levels. Same-day in vivo dual tracer imaging enabled by the Sel-tag technology and (11)C-labeling provides a method to non-invasively monitor membrane-localized EGFR as well as factors affecting non-specific uptake of the PET ligand.

A cross sectional survey of attitudes, awareness and uptake of the parental pertussis booster vaccine as part of a cocooning strategy, Victoria, Australia

PubMed Central

2013-01-01

Background The Victorian Government Department of Health funded a diphtheria, tetanus and acellular pertussis vaccine for parents of infants from June 2009 to June 2012 as part of a cocooning strategy for the control of pertussis. The aim of this study was to assess parents’ attitudes and awareness of the vaccination program, and to estimate vaccine uptake. Methods A cross-sectional survey of 253 families with a child born in the first quarter of 2010 residing within five metropolitan and four rural local government areas in Victoria was conducted. Univariate analyses were performed to describe the relationship between demographic variables, knowledge and awareness of the disease, the vaccine program and vaccine uptake. Multivariate analyses examining predictors for awareness of the vaccine program and for the uptake of vaccination were also conducted. Results One hundred and five families were surveyed (response rate 43%). Of these, 93% indicated that they had heard of ‘pertussis’ or ‘whooping cough’ and 75% of mothers and 69% of fathers were aware the pertussis vaccine was available and funded for new parents. Overall, 70% of mothers and 53% of fathers were vaccinated following their child’s birth, with metropolitan fathers less likely to be vaccinated as rural fathers (RR = 0.6, p = 0.002). Being a younger mother (p = 0.02) or father (p = 0.047), and being an Australian-born father (RR = 1.9, p = 0.03) were found to predict uptake of the vaccine in parents. Conclusion Parents indicated a reasonable level of knowledge of pertussis and a willingness to be vaccinated to protect their child. However, vaccine uptake estimates indicated further opportunity for program improvement. Future cocooning strategies would benefit from specifically targeting fathers and metropolitan maternity hospitals to increase vaccine uptake. Wider promotion of the availability of vaccine providers may increase uptake to maximise the success of cocooning programs. Further investigation of the effectiveness of the cocooning strategy in decreasing infant morbidity and mortality is required. PMID:23875762

Real-time monitoring of specific oxygen uptake rates of embryonic stem cells in a microfluidic cell culture device.

PubMed

Super, Alexandre; Jaccard, Nicolas; Cardoso Marques, Marco Paulo; Macown, Rhys Jarred; Griffin, Lewis Donald; Veraitch, Farlan Singh; Szita, Nicolas

2016-09-01

Oxygen plays a key role in stem cell biology as a signaling molecule and as an indicator of cell energy metabolism. Quantification of cellular oxygen kinetics, i.e. the determination of specific oxygen uptake rates (sOURs), is routinely used to understand metabolic shifts. However current methods to determine sOUR in adherent cell cultures rely on cell sampling, which impacts on cellular phenotype. We present real-time monitoring of cell growth from phase contrast microscopy images, and of respiration using optical sensors for dissolved oxygen. Time-course data for bulk and peri-cellular oxygen concentrations obtained for Chinese hamster ovary (CHO) and mouse embryonic stem cell (mESCs) cultures successfully demonstrated this non-invasive and label-free approach. Additionally, we confirmed non-invasive detection of cellular responses to rapidly changing culture conditions by exposing the cells to mitochondrial inhibiting and uncoupling agents. For the CHO and mESCs, sOUR values between 8 and 60 amol cell(-1) s(-1) , and 5 and 35 amol cell(-1) s(-1) were obtained, respectively. These values compare favorably with literature data. The capability to monitor oxygen tensions, cell growth, and sOUR, of adherent stem cell cultures, non-invasively and in real time, will be of significant benefit for future studies in stem cell biology and stem cell-based therapies. © 2016 The Authors. Biotechnology Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanoparticle tumor localization, disruption of autophagosomal trafficking, and prolonged drug delivery improve survival in peritoneal mesothelioma.

PubMed

Liu, Rong; Colby, Aaron H; Gilmore, Denis; Schulz, Morgan; Zeng, Jialiu; Padera, Robert F; Shirihai, Orian; Grinstaff, Mark W; Colson, Yolonda L

2016-09-01

The treatment outcomes for malignant peritoneal mesothelioma are poor and associated with high co-morbidities due to suboptimal drug delivery. Thus, there is an unmet need for new approaches that concentrate drug at the tumor for a prolonged period of time yielding enhanced antitumor efficacy and improved metrics of treatment success. A paclitaxel-loaded pH-responsive expansile nanoparticle (PTX-eNP) system is described that addresses two unique challenges to improve the outcomes for peritoneal mesothelioma. First, following intraperitoneal administration, eNPs rapidly and specifically localize to tumors. The rate of eNP uptake by tumors is an order of magnitude faster than the rate of uptake in non-malignant cells; and, subsequent accumulation in autophagosomes and disruption of autophagosomal trafficking leads to prolonged intracellular retention of eNPs. The net effect of these combined mechanisms manifests as rapid localization to intraperitoneal tumors within 4 h of injection and persistent intratumoral retention for >14 days. Second, the high tumor-specificity of PTX-eNPs leads to delivery of greater than 100 times higher concentrations of drug in tumors compared to PTX alone and this is maintained for at least seven days following administration. As a result, overall survival of animals with established mesothelioma more than doubled when animals were treated with multiple doses of PTX-eNPs compared to equivalent dosing with PTX or non-responsive PTX-loaded nanoparticles. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of simultaneously induced environmental stimuli on electrical signalling and gas exchange in maize plants.

PubMed

Vuralhan-Eckert, Jasmin; Lautner, Silke; Fromm, Jörg

2018-04-01

Electrical signalling in response to environmental stimuli is a well-known phenomenon in higher plants. For example, in maize, different stimuli, such as wounding or re-irrigation after drought, incite characteristic electrical signals which have quite particular effects on gas exchange. What is less well understood is how plants (specifically maize) respond when two different environmental stimuli are applied simultaneously. To explore this, a three-stage experiment was designed. In the first stage, drought conditions were simulated by decreasing the soil water content to 30-40 % of field capacity. In these conditions, and in contrast to well-watered plants, the maize exhibited only 60-70% of the original level of stomatal conductance and 50-60 % of the original photosynthesis rate. In the second stage of the experiment the plants were re-irrigated and heat stimulated separately. Re-irrigation led to specific electrical signals followed by a gradual increase of gas exchange. In contrast, after heat stimulation of a leaf an electrical signal was evoked that reduced the net CO 2 -uptake rate as well as stomatal conductance. In the third stage, to elucidate how plants process simultaneous re-irrigation and heat stimulation, the drought-stressed maize plants were re-watered and heat-stimulated at the same time. Results showed a two phase response. In the first phase there was a rapid decrease in both the CO 2 uptake rate and the stomatal conductance, while in the second phase each of these parameters increased gradually. Thus, the results strongly support the view that the responses from both stimuli were combined, indicating that maize plants can process simultaneously applied stimuli. Copyright © 2018 Elsevier GmbH. All rights reserved.

Comparison of mineral weathering and biomass nutrient uptake in two small forested watersheds underlain by quartzite bedrock, Catoctin Mountain, Maryland, USA

USGS Publications Warehouse

Rice, Karen; Price, Jason R.

2014-01-01

To quantify chemical weathering and biological uptake, mass-balance calculations were performed on two small forested watersheds located in the Blue Ridge Physiographic Province in north-central Maryland, USA. Both watersheds, Bear Branch (BB) and Fishing Creek Tributary (FCT), are underlain by relatively unreactive quartzite bedrock. Such unreactive bedrock and associated low chemical-weathering rates offer the opportunity to quantify biological processes operating within the watershed. Hydrologic and stream-water chemistry data were collected from the two watersheds for the 9-year period from June 1, 1990 to May 31, 1999. Of the two watersheds, FCT exhibited both higher chemical-weathering rates and biomass nutrient uptake rates, suggesting that forest biomass aggradation was limited by the rate of chemical weathering of the bedrock. Although the chemical-weathering rate in the FCT watershed was low relative to the global average, it masked the influence of biomass base-cation uptake on stream-water chemistry. Any differences in bedrock mineralogy between the two watersheds did not exert a significant influence on the overall weathering stoichiometry. The difference in chemical-weathering rates between the two watersheds is best explained by a larger proportion of reactive phyllitic layers within the bedrock of the FCT watershed. Although the stream gradient of BB is about two-times greater than that of FCT, its influence on chemical weathering appears to be negligible. The findings of this study support the biomass nutrient uptake stoichiometry of K1.0Mg1.1Ca0.97 previously determined for the study site. Investigations of the chemical weathering of relatively unreactive quartzite bedrock may provide insight into critical zone processes.

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.

Sarcoplasmic reticulum Ca2+ uptake and leak properties, and SERCA isoform expression, in type I and type II fibres of human skeletal muscle.

PubMed

Lamboley, C R; Murphy, R M; McKenna, M J; Lamb, G D

2014-03-15

The Ca(2+) uptake properties of the sarcoplasmic reticulum (SR) were compared between type I and type II fibres of vastus lateralis muscle of young healthy adults. Individual mechanically skinned muscle fibres were exposed to solutions with the free [Ca(2+)] heavily buffered in the pCa range (-log10[Ca(2+)]) 7.3-6.0 for set times and the amount of net SR Ca(2+) accumulation determined from the force response elicited upon emptying the SR of all Ca(2+). Western blotting was used to determine fibre type and the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) isoform present in every fibre examined. Type I fibres contained only SERCA2 and displayed half-maximal Ca(2+) uptake rate at ∼pCa 6.8, whereas type II fibres contained only SERCA1 and displayed half-maximal Ca(2+) uptake rate at ∼pCa 6.6. Maximal Ca(2+) uptake rate was ∼0.18 and ∼0.21 mmol Ca(2+) (l fibre)(-1) s(-1) in type I and type II fibres, respectively, in good accord with previously measured SR ATPase activity. Increasing free [Mg(2+)] from 1 to 3 mM had no significant effect on the net Ca(2+) uptake rate at pCa 6.0, indicating that there was little or no calcium-induced calcium release occurring through the Ca(2+) release channels during uptake in either fibre type. Ca(2+) leakage from the SR at pCa 8.5, which is thought to occur at least in part through the SERCA, was ∼2-fold lower in type II fibres than in type I fibres, and was little affected by the presence of ADP, in marked contrast to the larger SR Ca(2+) leak observed in rat muscle fibres under the same conditions. The higher affinity of Ca(2+) uptake in the type I human fibres can account for the higher relative level of SR Ca(2+) loading observed in type I compared to type II fibres, and the SR Ca(2+) leakage characteristics of the human fibres suggest that the SERCAs are regulated differently from those in rat and contribute comparatively less to resting metabolic rate.

Bulk chlorine uptake by polyamide active layers of thin-film composite membranes upon exposure to free chlorine-kinetics, mechanisms, and modeling.

PubMed

Powell, Joshua; Luh, Jeanne; Coronell, Orlando

2014-01-01

We studied the volume-averaged chlorine (Cl) uptake into the bulk region of the aromatic polyamide active layer of a reverse osmosis membrane upon exposure to free chlorine. Volume-averaged measurements were obtained using Rutherford backscattering spectrometry with samples prepared at a range of free chlorine concentrations, exposure times, and mixing, rinsing, and pH conditions. Our volume-averaged measurements complement previous studies that have quantified Cl uptake at the active layer surface (top ≈ 7 nm) and advance the mechanistic understanding of Cl uptake by aromatic polyamide active layers. Our results show that surface Cl uptake is representative of and underestimates volume-averaged Cl uptake under acidic conditions and alkaline conditions, respectively. Our results also support that (i) under acidic conditions, N-chlorination followed by Orton rearrangement is the dominant Cl uptake mechanism with N-chlorination as the rate-limiting step; (ii) under alkaline conditions, N-chlorination and dechlorination of N-chlorinated amide links by hydroxyl ion are the two dominant processes; and (iii) under neutral pH conditions, the rates of N-chlorination and Orton rearrangement are comparable. We propose a kinetic model that satisfactorily describes Cl uptake under acidic and alkaline conditions, with the largest discrepancies between model and experiment occurring under alkaline conditions at relatively high chlorine exposures.

Exercise-induced muscle glucose uptake in mice with graded, muscle-specific GLUT-4 deletion.

PubMed

Howlett, Kirsten F; Andrikopoulos, Sofianos; Proietto, Joseph; Hargreaves, Mark

2013-08-01

To investigate the importance of the glucose transporter GLUT-4 for muscle glucose uptake during exercise, transgenic mice with skeletal muscle GLUT-4 expression approximately 30-60% of normal (CON) and approximately 5-10% of normal (KO) were generated using the Cre/Lox system and compared with wild-type (WT) mice during approximately 40 min of treadmill running (KO: 37.7 ± 1.3 min; WT: 40 min; CON: 40 min, P = 0.18). In WT and CON animals, exercise resulted in an overall increase in muscle glucose uptake. More specifically, glucose uptake was increased in red gastrocnemius of WT mice and in the soleus and red gastrocnemius of CON mice. In contrast, the exercise-induced increase in muscle glucose uptake in all muscles was completely abolished in KO mice. Muscle glucose uptake increased during exercise in both red and white quadriceps of WT mice, while the small increases in CON mice were not statistically significant. In KO mice, there was no change at all in quadriceps muscle glucose uptake. No differences in muscle glycogen use during exercise were observed between any of the groups. However, there was a significant increase in plasma glucose levels after exercise in KO mice. The results of this study demonstrated that a reduction in skeletal muscle GLUT-4 expression to approximately 10% of normal levels completely abolished the exercise-induced increase in muscle glucose uptake.

Sexual behavior and factors associated with young age at first intercourse and HPV vaccine uptake among young women in Germany: implications for HPV vaccination policies.

PubMed

Remschmidt, Cornelius; Fesenfeld, Michaela; Kaufmann, Andreas M; Deleré, Yvonne

2014-12-05

In Germany, immunization against human papillomaviruses (HPV) is free of charge for all females aged 12 to 17 years. Since HPV infection rates rise soon after first intercourse, immunization against HPV should be completed before sexual debut. Knowledge of country-specific data on age at first intercourse and related risk factors is important to optimize prevention of HPV and other sexually transmitted infections. Therefore, the primary aim of this study was to describe sexual behavior in young women in Germany. Secondary aims were to identify factors that are (i) associated with younger age at first intercourse and (ii) with HPV vaccine uptake. Between 2010 and 2012, we conducted a cross-sectional study among randomly selected women aged 20 to 25 years in Germany. We used a structured, self-administered questionnaire to collect sociodemographic data, information on sexual habits such as age at first intercourse, and information on HPV vaccine uptake. We used univariate and multivariate logistic regression analyses to identify factors associated with younger age at first intercourse and with HPV vaccine uptake. A total of 823 women (response rate: 14.2%) participated, 785 (95.4%) of which reported having had intercourse already. 70% of these women experienced first intercourse before the age of 18 years. However, less than 5% were younger than 14 years at sexual debut. Younger age at first intercourse was independently associated with a higher number of sexual partners, smoking, and past pregnancies. HPV vaccine uptake was associated with higher education, whereas smoking and a migrant background reduced the chance of being vaccinated. In Germany, only a small proportion of women experienced first intercourse before the age of 14 years. Younger age at first intercourse was associated with behavior that might increase the risk of HPV infections or other sexually transmitted infections. Therefore, to optimize the HPV vaccination strategy, HPV vaccination series should be completed before the age of 14 years in Germany.

Direct determination of the driving forces for taurocholate uptake into rat liver plasma membrane vesicles.

PubMed

Duffy, M C; Blitzer, B L; Boyer, J L

1983-10-01

To determine directly the driving forces for bile acid entry into the hepatocyte, the uptake of [3H]taurocholic acid into rat liver plasma membrane vesicles was studied. The membrane preparation contained predominantly right-side-out vesicles, and was highly enriched in plasma membrane marker enzymes. The uptake of taurocholate at equilibrium was inversely related to medium osmolarity, indicating transport into an osmotically sensitive space. In the presence of an inwardly directed sodium gradient (NaCl or sodium gluconate), the initial rate of uptake was rapid and taurocholate was transiently accumulated at a concentration twice that at equilibrium (overshoot). Other inwardly directed cation gradients (K+, Li+, choline+) or the presence of sodium in the absence of a gradient (Na+ equilibrated) resulted in a slower initial uptake rate and did not sustain an overshoot. Bile acids inhibited sodium-dependent taurocholate uptake, whereas bromsulphthalein inhibited both sodium-dependent and sodium-independent uptake and D-glucose had no effect on uptake. Uptake was temperature dependent, with maximal overshoots occurring at 25 degrees C. Imposition of a proton gradient across the vesicle (pHo less than pHi) in the absence of a sodium gradient failed to enhance taurocholate uptake, indicating that double ion exchange (Na+-H+, OH- -anion) is unlikely. Creation of a negative intravesicular potential by altering accompanying anions or by valinomycin-induced K+-diffusion potentials did not enhance taurocholate uptake, suggesting an electroneutral transport mechanism. The kinetics of taurocholate uptake demonstrated saturability with a Michaelis constant at 52 microM and maximum velocity of 4.5 nmol X mg-1 X protein X min-1. These studies provide definitive evidence for a sodium gradient-dependent, carrier-mediated, electrically neutral transport mechanism for hepatic taurocholate uptake. These findings are consistent with a model for bile secretion in which the basolateral enzyme Na+,K+-ATPase provides the driving force for "uphill" bile acid transport by establishing a trans-membrane sodium gradient.

Increasing uptake rates of cervical cancer screening amongst Hong Kong Chinese women: the role of the practitioner.

PubMed

Twinn, S; Cheng, F

2000-08-01

Women's attendance for regular cervical screening has been identified as a significant factor in the prevention of cervical cancer. Evidence suggests, however, that both extrinsic and intrinsic factors influence women's attendance patterns for screening. Extrinsic factors, in particular the practitioner undertaking the screening procedure, have been shown to influence women's return rates for further screening. In Hong Kong, where uptake rates amongst Chinese women remain comparatively low, a study was undertaken to examine Chinese women's experiences and perceptions of cervical screening undertaken by either a female doctor or nurse. A multiple case study design using both qualitative and quantitative methods of data collection was employed. This paper reports the findings from the qualitative data obtained from 52 women participating in 12 focus group interviews held in the two case studies. Thematic analysis of the data demonstrated the importance of the caring nature, communication skills, experience and expertise of the practitioner to women's attendance pattern for screening. The experience and expertise of the practitioner, described by women as teaching, minimizing pain and discomfort and being considerate, were considered more influential to uptake rates than the professional discipline of the practitioner. Findings such as these indicate the importance of the influence of the practitioner in determining uptake rates for cervical screening amongst this population group.

Ethanol production during semi-continuous syngas fermentation in a trickle bed reactor using Clostridium ragsdalei.

PubMed

Devarapalli, Mamatha; Atiyeh, Hasan K; Phillips, John R; Lewis, Randy S; Huhnke, Raymond L

2016-06-01

An efficient syngas fermentation bioreactor provides a mass transfer capability that matches the intrinsic kinetics of the microorganism to obtain high gas conversion efficiency and productivity. In this study, mass transfer and gas utilization efficiencies of a trickle bed reactor during syngas fermentation by Clostridium ragsdalei were evaluated at various gas and liquid flow rates. Fermentations were performed using a syngas mixture of 38% CO, 28.5% CO2, 28.5% H2 and 5% N2, by volume. Results showed that increasing the gas flow rate from 2.3 to 4.6sccm increased the CO uptake rate by 76% and decreased the H2 uptake rate by 51% up to Run R6. Biofilm formation after R6 increased cells activity with over threefold increase in H2 uptake rate. At 1662h, the final ethanol and acetic acid concentrations were 5.7 and 12.3g/L, respectively, at 200ml/min of liquid flow rate and 4.6sccm gas flow rate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Taking hospital treatments home: a mixed methods case study looking at the barriers and success factors for home dialysis treatment and the influence of a target on uptake rates.

PubMed

Combes, Gill; Allen, Kerry; Sein, Kim; Girling, Alan; Lilford, Richard

2015-10-27

Despite healthcare policies and evidence which promote home dialysis, uptake rates have been falling for over 10 years in England. A target introduced by commissioners in the West Midlands provided a unique opportunity to study how hospitals can increase home-based treatment for a group of patients with complex life-threatening conditions. Quantitative changes in home treatment uptake rates in seven hospitals in the West Midlands were compared with the rest of England for 3 years pre and post the introduction of the target in 2010, using a logistic regression model. Qualitative interviews in four hospitals with 96 clinical and managerial staff and 93 dialysis patients explored the barriers and facilitators to increasing the uptake of home treatment and the impact of the target. Home treatment uptake rates increased significantly in the seven study hospitals compared with the 3 years prior to the introduction of the target and compared with the rest of England where rates remained static. The four main factors facilitating increased uptake were as follows: the commissioner's target, linked to financial penalties; additional funding for specialist staff and equipment; committed, visible clinical champions and good systems for patient training and ongoing healthcare support at home. The three main barriers were as follows: lack of training for non-specialist staff, poorly developed patient education and considerable unrecognised and unmet emotional and psychological patient needs. This study shows the impact of using targets with financial penalties to achieve change and how hospitals can increase significantly the uptake of home-based self-care for a group of patients with complex medical needs. It provides useful pointers to the main barriers and facilitators, which are likely to be relevant to other groups of patients who could be treated at home. It also highlights two neglected areas which need to improve if patients with life-threatening long-term conditions are to be encouraged to take up home treatment: individualised patient education which allows exploration of the impacts of treatment options and the provision of ongoing emotional support.

In situ Measurements of Dissolved Gas Dynamics and Root Uptake in the Wetland Rhizosphere

NASA Astrophysics Data System (ADS)

Reid, Matthew; Jaffe, Peter

2013-04-01

Anaerobic wetland soils are important natural sources of various atmospheric trace gases that are detrimental to the environment, including methane (CH4), nitrous oxide, elemental mercury (Hg°), and halomethanes. The balance between production and uptake in soils depends, in part, on mass transfer within the soil and between soil and the atmosphere. Observed volatilization rates of trace gases are highly variable and poorly described by models, however, so there is a clear need for new process measurements to clarify the rates of these transport mechanisms. Here we present results from mesocosm push-pull tests intended to quantify transport processes of dissolved gases in wetland sediments, with a focus on uptake by wetland plant roots and partitioning into trapped gas bubbles. This technique uses a suite of nonreactive volatile tracers to pinpoint transport mechanisms without the confounding influence of biochemical transformations. Mass balance approaches are used to determine transport kinetics, and a new analytical method to interpret dissolved gas push-pull test data is presented and compared to traditional analytical techniques. Results confirm the key role of vegetation in dramatically enhancing removal rates of dissolved gases from wetland soils. Root uptake is shown to be diffusion-limited and relative root uptake rates are modeled as an empirical function of molecular size. We use the porewater removal rates measured here to estimate potential volatilization fluxes of CH4, methyl chloride, and Hg° from wetlands vegetated with Typha latifolia and Scirpus acutus. The implementation of this new push-pull test methodology to field settings will be discussed.

Similar specificities of symbiont uptake by adults and larvae in an anemone model system for coral biology

PubMed Central

Hambleton, Elizabeth A.; Guse, Annika; Pringle, John R.

2014-01-01

Reef-building corals depend for much of their energy on photosynthesis by symbiotic dinoflagellate algae (genus Symbiodinium) that live within their gastrodermal cells. However, the cellular mechanisms underpinning this ecologically critical symbiosis, including those governing the specificity of symbiont uptake by the host, remain poorly understood, in part because of the difficulties of working with corals in the laboratory. Here, we used the small symbiotic sea anemone Aiptasia as an experimentally tractable model system to analyze the specificity and timing of symbiosis onset in larval and adult animals under controlled laboratory conditions. Using four clonal, axenic Symbiodinium strains, we found no difference in uptake specificity between larvae (even when very young) and adults. Although both compatible and incompatible algal strains were found within the larval guts, only the former appeared to be internalized by gastrodermal cells, and they (but not incompatible algae) proliferated rapidly within the larvae in the absence of detectable exchange with other larvae. Older larvae showed reduced ingestion of both compatible and incompatible algae, and the addition of food failed to promote the uptake of an incompatible algal strain. Thus, Aiptasia adults and larvae appear to have similar mechanisms for discriminating between compatible and incompatible dinoflagellate types prior to phagocytosis by host gastrodermal cells. Whether a particular algal strain is compatible or incompatible appears to be stable during years of axenic culture in the absence of a host. These studies provide a foundation for future analyses of the mechanisms of symbiont-uptake specificity in this emerging model system. PMID:24526722

Radiosynthesis and ex vivo evaluation of (R)-(-)-2-chloro-N-[1-11C-propyl]n-propylnorapomorphine.

PubMed

Palner, Mikael; McCormick, Patrick; Gillings, Nic; Begtrup, Mikael; Wilson, Alan A; Knudsen, Gitte M

2010-01-01

Several dopamine D(2) agonist radioligands have been used with positron emission tomography (PET), including [(11)C-]-(-)-MNPA, [(11)C-]-(-)-NPA and [(11)C]-(+)-PHNO. These radioligands are considered particularly powerful for detection of endogenous dopamine release, but they either provide PET brain images with limited contrast or have affinity for both D(2) and D(3) receptors. We here present the carbon-11 radiolabeling and ex vivo evaluation of 2-Cl-(-)-NPA, a novel PET-tracer candidate with high in vitro D(2)/D(3) selectivity. 2-Cl-[(11)C]-(-)-NPA and [(11)C]-(-)-NPA were synthesized by a two step N-acylation-reduction process using [(11)C]-propionyl chloride. Awake rats were injected with either tracer, via the tail vein. The rats were decapitated at various times, the brains were removed and quickly dissected, and plasma metabolites were measured. Radioligand specificity, and P-glycoprotein involvement in brain uptake, was also assessed. 2-Cl-[(11)C]-(-)-NPA and [(11)C]-(-)-NPA were produced in high specific activity and purity. 2-Cl-[(11)C]-(-)-NPA accumulated slower in the striatum than [(11)C]-(-)-NPA, reaching maximum concentrations after 30 min. The maximal striatal uptake of 2-Cl-[(11)C]-(-)-NPA (standard uptake value 0.72+/-0.24) was approximately half that of [(11)C]-(-)-NPA (standard uptake value 1.37+/-0.18). Nonspecific uptake was similar for the two compounds. 2-Cl-[(11)C]-(-)-NPA was metabolized quickly, leaving only 17% of the parent compound in the plasma after 30 min. The specific binding of 2-Cl-[(11)C]-(-)-NPA was completely blocked and inhibition of P-glycoprotein did not alter the brain uptake. Ex vivo experiments showed, despite a favorable D(2)/D(3) selectivity, that 2-Cl-[(11)C]-(-)-NPA is inferior to [(11)C]-(-)-NPA as a PET tracer in rat, because of slower brain uptake and lower specific to nonspecific binding ratio. Copyright 2010 Elsevier Inc. All rights reserved.

Uptake and elimination kinetics of metals in soil invertebrates: a review.

PubMed

Ardestani, Masoud M; van Straalen, Nico M; van Gestel, Cornelis A M

2014-10-01

Uptake and elimination kinetics of metals in soil invertebrates are a function of both soil and organism properties. This study critically reviewed metal toxicokinetics in soil invertebrates and its potential use for assessing bioavailability. Uptake and elimination rate constants of different metals are summarized. Invertebrates have different strategies for essential and non-essential metals. As a consequence, different types of models must be applied to describe metal uptake and elimination kinetics. We discuss model parameters for each metal separately and show how they are influenced by exposure concentrations and by physiological properties of the organisms. Soil pH, cation exchange capacity, clay and organic matter content significantly affect uptake rates of non-essential metals in soil invertebrates. For essential metals, kinetics is hardly influenced by soil properties, but rather prone to physiological regulation mechanisms of the organisms. Our analysis illustrates that toxicokinetics can be a valuable measurement to assess bioavailability of soil-bound metals. Copyright © 2014 Elsevier Ltd. All rights reserved.

Plasma non-esterified docosahexaenoic acid is the major pool supplying the brain

PubMed Central

Chen, Chuck T.; Kitson, Alex P.; Hopperton, Kathryn E.; Domenichiello, Anthony F.; Trépanier, Marc-Olivier; Lin, Lauren E.; Ermini, Leonardo; Post, Martin; Thies, Frank; Bazinet, Richard P.

2015-01-01

Despite being critical for normal brain function, the pools that supply docosahexaenoic acid (DHA) to the brain are not agreed upon. Using multiple kinetic models in free-living adult rats, we first demonstrate that DHA uptake from the plasma non-esterified fatty acid (NEFA) pool predicts brain uptake of DHA upon oral administration, which enters the plasma NEFA pool as well as multiple plasma esterified pools. The rate of DHA loss by the brain is similar to the uptake from the plasma NEFA pool. Furthermore, upon acute iv administration, although more radiolabeled lysophosphatidylcholine (LPC)-DHA enters the brain than NEFA-DHA, this is due to the longer plasma half-life and exposure to the brain. Direct comparison of the uptake rate of LPC-DHA and NEFA-DHA demonstrates that uptake of NEFA-DHA into the brain is 10-fold greater than LPC-DHA. In conclusion, plasma NEFA-DHA is the major plasma pool supplying the brain. PMID:26511533

Concomitant uptake of antimicrobials and Salmonella in soil and into lettuce following wastewater irrigation.

PubMed

Sallach, J Brett; Zhang, Yuping; Hodges, Laurie; Snow, Daniel; Li, Xu; Bartelt-Hunt, Shannon

2015-02-01

The use of wastewater for irrigation may introduce antimicrobials and human pathogens into the food supply through vegetative uptake. The objective of this study was to investigate the uptake of three antimicrobials and Salmonella in two lettuce cultivars. After repeated subirrigation with synthetic wastewater, lettuce leaves and soil were collected at three sequential harvests. The internalization frequency of Salmonella in lettuce was low. A soil horizon-influenced Salmonella concentration gradient was determined with concentrations in bottom soil 2 log CFU/g higher than in top soil. Lincomycin and sulfamethoxazole were recovered from lettuce leaves at concentrations as high as 822 ng/g and 125 ng/g fresh weight, respectively. Antimicrobial concentrations in lettuce decreased from the first to the third harvest suggesting that the plant growth rate may exceed antimicrobial uptake rates. Accumulation of antimicrobials was significantly different between cultivars demonstrating a subspecies level variation in uptake of antibiotics in lettuce. Copyright © 2014 Elsevier Ltd. All rights reserved.

Tree specific traits vs. stand level characteristics - assessing the source depths of plant water uptake in a mixed forest stand

NASA Astrophysics Data System (ADS)

Seeger, Stefan; Brinkmann, Nadine; Kahmen, Ansgar; Weiler, Markus

2017-04-01

Due to differences in fine root distributions, physiological root characteristics and plant plasticity, the spatial and temporal characteristics of plant water uptake are expected to vary between different tree species. This has implications on the overall water budget of a forest stand as well as on the drought sensitivity of particular trees. A four-year time series of climate data, soil moisture, and stable water isotopes in soil and tree xylem was used to investigate plant water uptake dynamics of four tree species (beech - Fagus sylvatica, spruce - Picea abies, ash - Fraxinus excelsior and maple - Acer pseudoplatanus) in a mixed forest stand. Modeling with a modified version of the soil hydrological model Hydrus-1D allowed us to simulate continuous time series of stable water isotopes in plant water uptake, which were compared to the measured values in tree xylem water and soil water. We found that different estimated species specific fine root distributions and root water uptake parameters lead to very similar simulated water balances and soil water isotope depth profiles for all four species. According to our simulations, differences in evaporative demand (i.e. LAI) had the biggest influence on water uptake and soil water distributions. Comparing the isotopic signatures of simulated root water uptake and measured xylem water, the simulations for beech were most suited to predict the observed signatures of all four species. This indicates that isolated, tree specific parametrized 1-D simulations are not suited to predict actual water uptake of different trees in a mixed stand. Due to overlapping root spaces dominant trees (in our case beeches with an LAI of around 5.5) may influence the soil water storage below accompanying trees (spruces, ashes and maples with LAIs between 1.8 and 3.1) in a degree that their actual water uptake cannot be predicted with 1-D simulations based on their smaller LAI values. Consequently, for a mixed forest stand the interplay of trees with different traits has to be accounted for in order to correctly model plant water uptake of single trees.

Uptake of photosensitizers by bacteria is influenced by the presence of cations

NASA Astrophysics Data System (ADS)

Kishen, A.; George, S.

2007-05-01

This investigation studies the influence of cations on photosensitizer uptake by Enterococcus faecalis (gram positive) and Actinobacillus actinomycetemcomitans (gram negative). Methods- The uptake of Methylene blue (MB) and Indocyanine Green (ICG), by bacteria were studied under the influence of divalent cations (CaCl II & MgCl II) and EDTA. Further, E. faecalis cells subjected to trypsinisation and calcium channel blocker (verapamil) were also analysed for MB and ICG uptake inorder to understand the mechanism of photosensitizer uptake. Results- Uptake of ICG was enhanced in the presence of divalent cations in E. faecalis and A. actinomycetemcomitans. Treating cells with EDTA had no significant effect on the photosensitizer uptake, although the highest concentration tested showed an enhancement of uptake. In contrast to ICG, MB showed a decreased uptake by bacterial cells on subjecting them to divalent cations and EDTA. Calcium channel blocker had no significant inhibitory effect on photosensitizers uptake. However, trypsin treatment resulted in significant reduction of ICG uptake. The result suggested that ICG uptake by bacteria is mediated through specific transporter protein while MB is associated with the outer surface structures of bacterial cells.

Tests of bioaccumulation models for polychlorinated biphenyl compounds: a study of young-of-the-year bluefish in the Hudson River estuary, USA.

PubMed

Leblanc, Lawrence A; Buckel, Jeffrey A; Conover, David O; Brownawell, Bruce J

2006-08-01

A field-based study regarding uptake of polychlorinated biphenyl compounds (PCBs) by young-of-the-year (YOY) bluefish (Pomatomus saltatrix) was initiated to test a steady-state model of bioaccumulation and trophic transfer in a rapidly growing fish. Determination of prey composition as well as size-dependent growth and specific consumption rates for YOY bluefish from separate field and laboratory studies enabled the input of these species-specific parameters into the model. Furthermore, the time and duration of the exposure of YOY bluefish to dissolved PCBs from a well-characterized system (Hudson River, USA) was well known. Patterns of accumulation of individual PCB congeners differed relative to the accumulation of total PCBs, with the greatest net accumulation occurring for the higher-molecular-weight congeners. Comparison of lipid-normalized bioaccumulation factors (BAFs) with the octanol-water partition coefficients of individual PCB congeners revealed bluefish to be above the BAFs predicted by lipid-based equilibrium partitioning, suggesting that uptake from food is an important source of PCBs in YOY bluefish. Comparison of measured BAFs with values predicted by a steady-state, food-chain model showed good first-order agreement.

[Adaptive specific features of energy metabolism in fish ontogenesis].

PubMed

Ozerniuk, N D

2011-01-01

A review of data on the pattern of change of the intensity of oxygen consumption during early ontogenesis of different fish species (rainbow trout, loach, zebrafish, carp, and grass carp) is provided. It has a similar pattern: this index increases in the period of embryonic and larval development and, after passing of larvae to an active feeding, it begins to gradually decline. This dynamics is determined by specific features of an increase in the rate of oxygen uptake and body weight in the course of early stages of fish ontogenesis. For determining optimal temperature conditions of development, a method of total (for a definite stage of development) oxygen uptake was suggested, which makes it possible to determine minimal energy expenditures necessary for the process of a particular stage of embryogenesis to take place. Analysis of temperature dependence of kinetic properties of enzymes with reference to the Michaelis constant (Km) for lactate dehydrogenase demonstrated that minimal Km, corresponding to maximal enzyme-substrate affinity, for embryos of different fish species differs in correspondence with differences in temperature conditions of development of these species in nature. For embryos of one species developing at changing temperature conditions (salmonids), this index changes in accordance with a temperature drift in nature.

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

Effects of irrigation frequency and nitrogen fertilizer rate on water stress, nitrogen uptake, and plant growth of container-grown Rhododendron

USDA-ARS?s Scientific Manuscript database

The influence of irrigation frequency (same amount of water per day given at different times) and nitrogen (N) fertilizer rate on water stress (stomatal conductance, gs), N uptake, and growth (biomass) of container-grown evergreen Rhododendron ‘P.J.M. Compact’ and ‘English Roseum’ and deciduous Rhod...

What shapes research impact on policy? Understanding research uptake in sexual and reproductive health policy processes in resource poor contexts

PubMed Central

2011-01-01

Assessing the impact that research evidence has on policy is complex. It involves consideration of conceptual issues of what determines research impact and policy change. There are also a range of methodological issues relating to the question of attribution and the counter-factual. The dynamics of SRH, HIV and AIDS, like many policy arenas, are partly generic and partly issue- and context-specific. Against this background, this article reviews some of the main conceptualisations of research impact on policy, including generic determinants of research impact identified across a range of settings, as well as the specificities of SRH in particular. We find that there is scope for greater cross-fertilisation of concepts, models and experiences between public health researchers and political scientists working in international development and research impact evaluation. We identify aspects of the policy landscape and drivers of policy change commonly occurring across multiple sectors and studies to create a framework that researchers can use to examine the influences on research uptake in specific settings, in order to guide attempts to ensure uptake of their findings. This framework has the advantage that distinguishes between pre-existing factors influencing uptake and the ways in which researchers can actively influence the policy landscape and promote research uptake through their policy engagement actions and strategies. We apply this framework to examples from the case study papers in this supplement, with specific discussion about the dynamics of SRH policy processes in resource poor contexts. We conclude by highlighting the need for continued multi-sectoral work on understanding and measuring research uptake and for prospective approaches to receive greater attention from policy analysts. PMID:21679384

Comparative Studies on the Toxicokinetics of Benzo[a]pyrene in Pinctada martensii and Perna viridis.

PubMed

Wang, Haihua; Cui, Lili; Cheng, Huamin; Zhang, Yu; Diao, Xiaoping; Wang, Jun

2017-05-01

Research on the kinetics of Benzo[a]pyrene (B[a]P) bioaccumulation in the clam Pinctada martensii and mussel Perna viridis showed that the initial rate of uptake was directly related to the PAH concentrations in the ambient environment. The uptake and depuration rate constants were different at the four B[a]P exposure levels, which indicated that the toxicokinetic rate constants mainly depended on the exposure levels of pollutants to the environment. In addition, the uptake rate constants of B[a]P were higher than the depuration rate constants in the entire experiment. The comparison demonstrated that mussels release B[a]P more rapidly than clams. The bioconcentration factors (BCFs) of B[a]P varied from 3335 to 12892 in the clam and 2373-6235 in the mussel. These findings on the bioaccumulation kinetics for petroleum hydrocarbons, in association with the critical body residue, will be valuable when choosing sensitive organisms to assess the potential ecotoxicological risk to the marine environment.

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.

Seasonal influenza vaccine uptake in HSE-funded hospitals and nursing homes during the 2011/2012 influenza season.

PubMed

O'Lorcain, P; Cotter, S; Hickey, L; O'Flanagan, D; Corcoran, B; O'Meara, M

2014-03-01

Annual seasonal influenza vaccine is recommended for all health care workers (HCWs) in Ireland. For the 2011/2012 influenza season, information was collected on influenza vaccination uptake among HCWs employed in Health Service Executive (HSE)-funded hospitals (primarily acute) and of nursing homes (NHs) and also among NH long-term and short-term respite care residents. Forty-five hospitals (80%) and 120 NHs (75%) provided uptake data. Nationally, influenza vaccine uptake among hospital employed HCWs was estimated to be 18% and 14% among HCWs in NHs; in NHs vaccine uptake among long-term care residents was estimated to 88%. These findings highlight the continued low uptake among HCWs of all categories and demonstrate the need for sustained measures to improve uptake rates.

Influence of taekwondo as security martial arts training on anaerobic threshold, cardiorespiratory fitness, and blood lactate recovery.

PubMed

Kim, Dae-Young; Seo, Byoung-Do; Choi, Pan-Am

2014-04-01

[Purpose] This study was conducted to determine the influence of Taekwondo as security martial arts training on anaerobic threshold, cardiorespiratory fitness, and blood lactate recovery. [Subjects and Methods] Fourteen healthy university students were recruited and divided into an exercise group and a control group (n = 7 in each group). The subjects who participated in the experiment were subjected to an exercise loading test in which anaerobic threshold, value of ventilation, oxygen uptake, maximal oxygen uptake, heart rate, and maximal values of ventilation / heart rate were measured during the exercise, immediately after maximum exercise loading, and at 1, 3, 5, 10, and 15 min of recovery. [Results] At the anaerobic threshold time point, the exercise group showed a significantly longer time to reach anaerobic threshold. The exercise group showed significantly higher values for the time to reach VO2max, maximal values of ventilation, maximal oxygen uptake and maximal values of ventilation / heart rate. Significant changes were observed in the value of ventilation volumes at the 1- and 5-min recovery time points within the exercise group; oxygen uptake and maximal oxygen uptake were significantly different at the 5- and 10-min time points; heart rate was significantly different at the 1- and 3-min time points; and maximal values of ventilation / heart rate was significantly different at the 5-min time point. The exercise group showed significant decreases in blood lactate levels at the 15- and 30-min recovery time points. [Conclusion] The study results revealed that Taekwondo as a security martial arts training increases the maximal oxygen uptake and anaerobic threshold and accelerates an individual's recovery to the normal state of cardiorespiratory fitness and blood lactate level. These results are expected to contribute to the execution of more effective security services in emergencies in which violence can occur.

Temporal variation in the importance of a dominant consumer to stream nutrient cycling

DOE PAGES

Griffiths, Natalie A.; Hill, Walter

2014-06-19

Animal excretion can be a significant nutrient flux within ecosystems, where it supports primary production and facilitates microbial decomposition of organic matter. The effects of excretory products on nutrient cycling have been documented for various species and ecosystems, but temporal variation in these processes is poorly understood. We examined variation in excretion rates of a dominant grazing snail, Elimia clavaeformis, and its contribution to nutrient cycling, over the course of 14 months in a well-studied, low-nutrient stream (Walker Branch, east Tennessee, USA). Biomass-specific excretion rates of ammonium varied over twofold during the study, coinciding with seasonal changes in food availabilitymore » (measured as gross primary production) and water temperature (multiple linear regression, R 2 = 0.57, P = 0.053). The contribution of ammonium excretion to nutrient cycling varied with seasonal changes in both biological (that is, nutrient uptake rate) and physical (that is, stream flow) variables. On average, ammonium excretion accounted for 58% of stream water ammonium concentrations, 26% of whole-stream nitrogen demand, and 66% of autotrophic nitrogen uptake. Phosphorus excretion by Elimia was contrastingly low throughout the year, supplying only 1% of total dissolved phosphorus concentrations. The high average N:P ratio (89:1) of snail excretion likely exacerbated phosphorus limitation in Walker Branch. To fully characterize animal excretion rates and effects on ecosystem processes, multiple measurements through time are necessary, especially in ecosystems that experience strong seasonality.« less

Metabolic Response of “Candidatus Accumulibacter Phosphatis” Clade II C to Changes in Influent P/C Ratio

PubMed Central

Welles, Laurens; Abbas, Ben; Sorokin, Dimitry Y.; Lopez-Vazquez, Carlos M.; Hooijmans, Christine M.; van Loosdrecht, Mark C. M.; Brdjanovic, Damir

2017-01-01

The objective of this study was to investigate the ability of a culture highly enriched with the polyphosphate-accumulating organism, “Candidatus Accumulibacter phosphatis” clade IIC, to adjust their metabolism to different phosphate availabilities. For this purpose the biomass was cultivated in a sequencing batch reactor with acetate and exposed to different phosphate/carbon influent ratios during six experimental phases. Activity tests were conducted to determine the anaerobic kinetic and stoichiometric parameters as well as the composition of the microbial community. Increasing influent phosphate concentrations led to increased poly-phosphate content and decreased glycogen content of the biomass. In response to higher biomass poly-phosphate content, the biomass showed higher specific phosphate release rates. Together with the phosphate release rates, acetate uptake rates also increased up to an optimal poly-phosphate/glycogen ratio of 0.3 P-mol/C-mol. At higher poly-phosphate/glycogen ratios (obtained at influent P/C ratios above 0.051 P-mol/C-mol), the acetate uptake rates started to decrease. The stoichiometry of the anaerobic conversions clearly demonstrated a metabolic shift from a glycogen dominated to a poly-phosphate dominated metabolism as the biomass poly-phosphate content increased. FISH and DGGE analyses confirmed that no significant changes occurred in the microbial community, suggesting that the changes in the biomass activity were due to different metabolic behavior, allowing the organisms to proliferate under conditions with fluctuating phosphate levels. PMID:28111570

Temporal variation in the importance of a dominant consumer to stream nutrient cycling

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

Griffiths, Natalie A.; Hill, Walter

Animal excretion can be a significant nutrient flux within ecosystems, where it supports primary production and facilitates microbial decomposition of organic matter. The effects of excretory products on nutrient cycling have been documented for various species and ecosystems, but temporal variation in these processes is poorly understood. We examined variation in excretion rates of a dominant grazing snail, Elimia clavaeformis, and its contribution to nutrient cycling, over the course of 14 months in a well-studied, low-nutrient stream (Walker Branch, east Tennessee, USA). Biomass-specific excretion rates of ammonium varied over twofold during the study, coinciding with seasonal changes in food availabilitymore » (measured as gross primary production) and water temperature (multiple linear regression, R 2 = 0.57, P = 0.053). The contribution of ammonium excretion to nutrient cycling varied with seasonal changes in both biological (that is, nutrient uptake rate) and physical (that is, stream flow) variables. On average, ammonium excretion accounted for 58% of stream water ammonium concentrations, 26% of whole-stream nitrogen demand, and 66% of autotrophic nitrogen uptake. Phosphorus excretion by Elimia was contrastingly low throughout the year, supplying only 1% of total dissolved phosphorus concentrations. The high average N:P ratio (89:1) of snail excretion likely exacerbated phosphorus limitation in Walker Branch. To fully characterize animal excretion rates and effects on ecosystem processes, multiple measurements through time are necessary, especially in ecosystems that experience strong seasonality.« less

Insulin resistance in striated muscle-specific integrin receptor beta1-deficient mice.

PubMed

Zong, Haihong; Bastie, Claire C; Xu, Jun; Fassler, Reinhard; Campbell, Kevin P; Kurland, Irwin J; Pessin, Jeffrey E

2009-02-13

Integrin receptor plays key roles in mediating both inside-out and outside-in signaling between cells and the extracellular matrix. We have observed that the tissue-specific loss of the integrin beta1 subunit in striated muscle results in a near complete loss of integrin beta1 subunit protein expression concomitant with a loss of talin and to a lesser extent, a reduction in F-actin content. Muscle-specific integrin beta1-deficient mice had no significant difference in food intake, weight gain, fasting glucose, and insulin levels with their littermate controls. However, dynamic analysis of glucose homeostasis using euglycemichyperinsulinemic clamps demonstrated a 44 and 48% reduction of insulin-stimulated glucose infusion rate and glucose clearance, respectively. The whole body insulin resistance resulted from a specific inhibition of skeletal muscle glucose uptake and glycogen synthesis without any significant effect on the insulin suppression of hepatic glucose output or insulin-stimulated glucose uptake in adipose tissue. The reduction in skeletal muscle insulin responsiveness occurred without any change in GLUT4 protein expression levels but was associated with an impairment of the insulin-stimulated protein kinase B/Akt serine 473 phosphorylation but not threonine 308. The inhibition of insulin-stimulated serine 473 phosphorylation occurred concomitantly with a decrease in integrin-linked kinase expression but with no change in the mTOR.Rictor.LST8 complex (mTORC2). These data demonstrate an in vivo crucial role of integrin beta1 signaling events in mediating cross-talk to that of insulin action.

Prostate-Specific Membrane Antigen Expression in Adrenocortical Carcinoma on 68Ga-Prostate-Specific Membrane Antigen PET/CT.

PubMed

Arora, Saurabh; Damle, Nishikant Avinash; Aggarwal, Sameer; Passah, Averilicia; Behera, Abhishek; Arora, Geetanjali; Bal, Chandrasekhar; Tripathi, Madhavi

2018-06-01

We present here a case of metastatic adrenocortical carcinoma with bilateral lung nodules. The patient had been treated with mitotane therapy initially and then was later referred for chemotherapy. There was progression of disease noted on the F-FDG PET/CT. Ga prostate-specific membrane antigen (PSMA) PET/CT was planned to explore the possibility of future treatment with Lu-DKFZ-PSMA-617. It revealed peripheral increased uptake of Ga-HBED-CC-PSMA equal to liver uptake.

Lethal and sublethal effects of chlorine, phenol, and chlorine-phenol mixtures on the mud crab, Panopeus herbstii.

PubMed

Key, P B; Scott, G I

1986-11-01

The mud crab, Panopeus herbstii, was acutely exposed (96-hr) to chlorine-produced oxidants (CPO), phenol, and a CPO-phenolic mixture (1:1) to determine lethal and sublethal effects. The 96-hr (LC50) values were determined for each individual compound and mixture. Additionally, whole-animal respiration rates were measured following acute exposure to sublethal concentrations of each compound or mixture. Phenol uptake/depuration rates were measured in the phenol and CPO-phenol mixture concentrations. Results indicated 96-hr LC50 values of 1.06 mg/L for CPO (fiducial limits (FL) = 0.53-2.01 mg/L), 52.8 mg/L for phenol (FL = 45.6-64.5 mg/L), and 184.7 mg/L total toxicant units (TTU) for the CPO-phenol mixture (FL = 143.7-250.2 mg/L TTU). Statistical analysis indicated that the acute toxicity of the CPO-phenol mixture was less than additive. Sublethal studies indicated that only acute exposure to sublethal concentrations of CPO caused altered respiration rates. After 96-hr depuration, metabolic rates in all CPO-exposure crabs generally returned to control rates. Uptake/depuration rate studies indicated significantly lower phenol uptake rates in crabs exposed to the CPO-phenol mixture. These findings suggest that the less-than-additive toxicity of the CPO-phenol mixture may result from lowered uptake/depuration rate kinetics and indicate that the discharge of chlorinated-phenolic waste may not result in additive and/or synergistic interactions, but rather in less-than-additive effects on decapod aquatic species.

Americium-241 uptake by Bahiagrass as influenced by soil type, lime, and organic matter

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

Hoyt, G.D.; Adriano, D.C.

1979-07-01

Availability of /sup 241/Am to bahiagrass (Paspalum notatum), a major forage crop in the southeastern US, was studied under greenhouse conditions using two soil types, two rates of lime, and four rates of organic matter. The plants were grown in pots until three clippings were obtained. Americium-241 concentrations in plant tissues from the unlimed Dothan (24% clay) soil were, on the average, approximately twice as high as those from unlimed Troup (10% clay) soil. Lime significantly reduced /sup 241/Am uptake from both soils. The americium concentration ratios (americium concentration in dry plant tissue/average americium concentration in dry soil) for limedmore » treatments were, in general, one order of magnitude lower than those for unlimed treatments. Organic matter, added to the soils as bermuda grass hay, somewhat reduced /sup 241/Am uptake, especially when added at high rates in unlimed soils. The effect of lime on uptake could be attributed to immobilization of americium ions external to the roots as a result of decreased solubility of this radionuclide and/or antagonistic effect of increased calcium ion concentration in the soil solution on americium ions. The effect of organic matter on uptake could be attributed to its fixing capacity for metals.« less

Catabolic efficiency of aerobic glycolysis: the Warburg effect revisited.

PubMed

Vazquez, Alexei; Liu, Jiangxia; Zhou, Yi; Oltvai, Zoltán N

2010-05-06

Cancer cells simultaneously exhibit glycolysis with lactate secretion and mitochondrial respiration even in the presence of oxygen, a phenomenon known as the Warburg effect. The maintenance of this mixed metabolic phenotype is seemingly counterintuitive given that aerobic glycolysis is far less efficient in terms of ATP yield per moles of glucose than mitochondrial respiration. Here, we resolve this apparent contradiction by expanding the notion of metabolic efficiency. We study a reduced flux balance model of ATP production that is constrained by the glucose uptake capacity and by the solvent capacity of the cell's cytoplasm, the latter quantifying the maximum amount of macromolecules that can occupy the intracellular space. At low glucose uptake rates we find that mitochondrial respiration is indeed the most efficient pathway for ATP generation. Above a threshold glucose uptake rate, however, a gradual activation of aerobic glycolysis and slight decrease of mitochondrial respiration results in the highest rate of ATP production. Our analyses indicate that the Warburg effect is a favorable catabolic state for all rapidly proliferating mammalian cells with high glucose uptake capacity. It arises because while aerobic glycolysis is less efficient than mitochondrial respiration in terms of ATP yield per glucose uptake, it is more efficient in terms of the required solvent capacity. These results may have direct relevance to chemotherapeutic strategies attempting to target cancer metabolism.

Acute changes in cellular zinc alters zinc uptake rates prior to zinc transporter gene expression in Jurkat cells.

PubMed

Holland, Tai C; Killilea, David W; Shenvi, Swapna V; King, Janet C

2015-12-01

A coordinated network of zinc transporters and binding proteins tightly regulate cellular zinc levels. Canonical responses to zinc availability are thought to be mediated by changes in gene expression of key zinc transporters. We investigated the temporal relationships of actual zinc uptake with patterns of gene expression in membrane-bound zinc transporters in the human immortalized T lymphocyte Jurkat cell line. Cellular zinc levels were elevated or reduced with exogenous zinc sulfate or N,N,N',N-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), respectively. Excess zinc resulted in a rapid 44 % decrease in the rate of zinc uptake within 10 min. After 120 min, the expression of metallothionein (positive control) increased, as well as the zinc exporter, ZnT1; however, the expression of zinc importers did not change during this time period. Zinc chelation with TPEN resulted in a rapid twofold increase in the rate of zinc uptake within 10 min. After 120 min, the expression of ZnT1 decreased, while again the expression of zinc importers did not change. Overall, zinc transporter gene expression kinetics did not match actual changes in cellular zinc uptake with exogenous zinc or TPEN treatments. This suggests zinc transporter regulation may be the initial response to changes in zinc within Jurkat cells.

A Comparative Study of Iron Uptake Mechanisms in Marine Microalgae: Iron Binding at the Cell Surface Is a Critical Step1[W][OA

PubMed Central

Sutak, Robert; Botebol, Hugo; Blaiseau, Pierre-Louis; Léger, Thibaut; Bouget, François-Yves; Camadro, Jean-Michel; Lesuisse, Emmanuel

2012-01-01

We investigated iron uptake mechanisms in five marine microalgae from different ecologically important phyla: the diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana, the prasinophyceae Ostreococcus tauri and Micromonas pusilla, and the coccolithophore Emiliania huxleyi. Among these species, only the two diatoms were clearly able to reduce iron, via an inducible (P. tricornutum) or constitutive (T. pseudonana) ferrireductase system displaying characteristics similar to the yeast (Saccharomyces cerevisiae) flavohemoproteins proteins. Iron uptake mechanisms probably involve very different components according to the species, but the species we studied shared common features. Regardless of the presence and/or induction of a ferrireductase system, all the species were able to take up both ferric and ferrous iron, and iron reduction was not a prerequisite for uptake. Iron uptake decreased with increasing the affinity constants of iron-ligand complexes and with increasing ligand-iron ratios. Therefore, at least one step of the iron uptake mechanism involves a thermodynamically controlled process. Another step escapes to simple thermodynamic rules and involves specific and strong binding of ferric as well as ferrous iron at the cell surface before uptake of iron. Binding was paradoxically increased in iron-rich conditions, whereas uptake per se was induced in all species only after prolonged iron deprivation. We sought cell proteins loaded with iron following iron uptake. One such protein in O. tauri may be ferritin, and in P. tricornutum, Isip1 may be involved. We conclude that the species we studied have uptake systems for both ferric and ferrous iron, both involving specific iron binding at the cell surface. PMID:23033141

Tau Antibody Targeting Pathological Species Blocks Neuronal Uptake and Interneuron Propagation of Tau in Vitro.

PubMed

Nobuhara, Chloe K; DeVos, Sarah L; Commins, Caitlin; Wegmann, Susanne; Moore, Benjamin D; Roe, Allyson D; Costantino, Isabel; Frosch, Matthew P; Pitstick, Rose; Carlson, George A; Hock, Christoph; Nitsch, Roger M; Montrasio, Fabio; Grimm, Jan; Cheung, Anne E; Dunah, Anthone W; Wittmann, Marion; Bussiere, Thierry; Weinreb, Paul H; Hyman, Bradley T; Takeda, Shuko

2017-06-01

The clinical progression of Alzheimer disease (AD) is associated with the accumulation of tau neurofibrillary tangles, which may spread throughout the cortex by interneuronal tau transfer. If so, targeting extracellular tau species may slow the spreading of tau pathology and possibly cognitive decline. To identify suitable target epitopes, we tested the effects of a panel of tau antibodies on neuronal uptake and aggregation in vitro. Immunodepletion was performed on brain extract from tau-transgenic mice and postmortem AD brain and added to a sensitive fluorescence resonance energy transfer-based tau uptake assay to assess blocking efficacy. The antibodies reduced tau uptake in an epitope-dependent manner: N-terminal (Tau13) and middomain (6C5 and HT7) antibodies successfully prevented uptake of tau species, whereas the distal C-terminal-specific antibody (Tau46) had little effect. Phosphorylation-dependent (40E8 and p396) and C-terminal half (4E4) tau antibodies also reduced tau uptake despite removing less total tau by immunodepletion, suggesting specific interactions with species involved in uptake. Among the seven antibodies evaluated, 6C5 most efficiently blocked uptake and subsequent aggregation. More important, 6C5 also blocked neuron-to-neuron spreading of tau in a unique three-chamber microfluidic device. Furthermore, 6C5 slowed down the progression of tau aggregation even after uptake had begun. Our results imply that not all antibodies/epitopes are equally robust in terms of blocking tau uptake of human AD-derived tau species. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

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.

From Experiments to Simulations: Downscaling Measurements of Na+ Distribution at the Root-Soil Interface

NASA Astrophysics Data System (ADS)

Perelman, A.; Guerra, H. J.; Pohlmeier, A. J.; Vanderborght, J.; Lazarovitch, N.

2017-12-01

When salinity increases beyond a certain threshold, crop yield will decrease at a fixed rate, according to the Maas and Hoffman model (1976). Thus, it is highly important to predict salinization and its impact on crops. Current models do not consider the impact of the transpiration rate on plant salt tolerance, although it affects plant water uptake and thus salt accumulation around the roots, consequently influencing the plant's sensitivity to salinity. Better model parametrization can improve the prediction of real salinity effects on crop growth and yield. The aim of this research is to study Na+ distribution around roots at different scales using different non-invasive methods, and to examine how this distribution is affected by the transpiration rate and plant water uptake. Results from tomato plants that were grown on rhizoslides (a capillary paper growth system) showed that the Na+ concentration was higher at the root-substrate interface than in the bulk. Also, Na+ accumulation around the roots decreased under a low transpiration rate, supporting our hypothesis. The rhizoslides enabled the root growth rate and architecture to be studied under different salinity levels. The root system architecture was retrieved from photos taken during the experiment, enabling us to incorporate real root systems into a simulation. Magnetic resonance imaging (MRI) was used to observe correlations between root system architectures and Na+ distribution. The MRI provided fine resolution of the Na+ accumulation around a single root without disturbing the root system. With time, Na+ accumulated only where roots were found in the soil and later around specific roots. Rhizoslides allow the root systems of larger plants to be investigated, but this method is limited by the medium (paper) and the dimension (2D). The MRI can create a 3D image of Na+ accumulation in soil on a microscopic scale. These data are being used for model calibration, which is expected to enable the prediction of root water uptake in saline soils for different climatic conditions and different soil water availabilities.

Improving influenza vaccine uptake in frontline staff.

PubMed

Aziz, Ann-Marie

Influenza is a highly contagious upper respiratory tract disease causing significant morbidity and mortality among high-risk groups. Immunization of frontline healthcare workers (HCWs) in the NHS is thought to be beneficial in reducing subclinical infection, staff sickness absences and protects patients. Each year Public Health England launches the Seasonal Flu Campaign to help reduce influenza transmission by reinforcing the message that it is vital that frontline HCWs get vaccinated. Public Health produces figures on frontline workers who have been vaccinated annually. The 2011/2012 campaign showed uptake figures of the influenza vaccine was averaging 44.6% nationally. The efforts of an NHS trust to increase staff uptake of the annual seasonal flu vaccination programme has been highly commended as it achieved an impressive 68.7% uptake against a target of 70%. This article shows how the trust worked hard to improve uptake on flu vaccinations for HCWs during the 2012/2013 flu season. Recognised as a Top Improver by NHS Employers (2013) for vaccination uptake, the Trust identifies how measures can be adopted to improve vaccination rates and what barriers can prevent total compliance. High rates of HCW vaccination can benefit staff, patients and the communities within which they work and live.

Transport of adenine, hypoxanthine and uracil into Escherichia coli.

PubMed Central

Burton, K

1977-01-01

Uptake of adenine, hypoxanthine and uracil by an uncA strain of Escherichia coli is inhibited by uncouplers or when phosphate in the medium is replaced by less than 1 mM-arsenate, indicating a need for both a protonmotive force and phosphorylated metabolites. The rate of uptake of adenine or hypoxanthine was not markedly affected by a genetic deficiency of purine nucleoside phosphorylase. In two mutants with undetected adenine phosphoribosyltransferase, the rate of adenine uptake was about 30% of that in their parent strain, and evidence was obtained to confirm that adenine had then been utilized via purine nucleoside phosphorylase. In a strain deficient in both enzymes adenine uptake was about 1% of that shown by wild-type strains. Uptake of hypoxanthine was similarly limited in a strain lacking purine nucleoside phosphorylase, hypoxanthine phosphoribosyltransferase and guanine phosphoribosyltransferase. Deficiency of uracil phosphoribosyltransferase severely limits uracil uptake, but the defect can be circumvented by addition of inosine, which presumably provides ribose 1-phosphate for reversal of uridine phosphorylase. The results indicate that there are porter systems for adenine, hypoxanthine and uracil dependent on a protonmotive force and facilitated by intracellular metabolism of the free bases. PMID:413544

Side-by-Side Comparison of Commonly Used Biomolecules That Differ in Size and Affinity on Tumor Uptake and Internalization

PubMed Central

Leelawattanachai, Jeerapond; Kwon, Keon-Woo; Michael, Praveesuda; Ting, Richard; Kim, Ju-Young; Jin, Moonsoo M.

2015-01-01

The ability to use a systemically injected agent to image tumor is influenced by tumor characteristics such as permeability and vascularity, and the size, shape, and affinity of the imaging agent. In this study, six different imaging biomolecules, with or without specificity to tumor, were examined for tumor uptake and internalization at the whole body, ex-vivo tissue, and cellular levels: antibodies, antibody fragments (Fab), serum albumin, and streptavidin. The time of peak tumor uptake was dependent solely on the size of molecules, suggesting that molecular size is the major factor that influences tumor uptake by its effect on systemic clearance and diffusion into tumor. Affinity to tumor antigen failed to augment tumor uptake of Fab above non-specific accumulation, which suggests that Fab fragments of typical monoclonal antibodies may fall below an affinity threshold for use as molecular imaging agents. Despite abundant localization into the tumor, albumin and streptavidin were not found on cell surface or inside cells. By comparing biomolecules differing in size and affinity, our study highlights that while pharmacokinetics are a dominant factor in tumor uptake for biomolecules, affinity to tumor antigen is required for tumor binding and internalization. PMID:25901755

Bone scintigraphy in the investigation of occult lameness in the dog.

PubMed

Schwarz, T; Johnson, V S; Voute, L; Sullivan, M

2004-05-01

99mTechnetium methylene diphosphonate (99mTc-MDP) scintigraphy was performed in 14 dogs of different breeds after clinical lameness examination, radiography and synovial fluid analysis failed to localise lameness to a specific area of pain. The scintigraphic protocol included an intravenous injection of 17 MBq 99mTc-MDP/kg bodyweight and vascular, soft tissue and bone phase scans in standardised positions with a low-energy all-purpose collimator. Confirmation of diagnosis was achieved in nine dogs by arthroscopy, repeated lesion-orientated radiography, computed tomography and response to treatment. In seven cases, bone phase scans showed single elbow uptakes, in two cases unilateral limb uptake, and in one case each a single shoulder and tibia uptake; in three cases there was no increased uptake. Vascular and soft tissue phase images did not reveal additional information. Diagnosis of humeral condyle fissures, a fragmented medial coronoid process, panosteitis and arthropathy was possible in nine cases. Skeletal pathology was ruled out in three normal scintigrams. In two dogs with unilateral uptake of multiple joints, no diagnostic benefit was gained from scintigraphy. The highly sensitive and relatively specific uptake allowed localisation and characterisation or exclusion of skeletal lesions in most dogs.

Characterization of the biotin uptake system encoded by the biotin-inducible bioYMN operon of Corynebacterium glutamicum

PubMed Central

2012-01-01

Background The amino acid-producing Gram-positive Corynebacterium glutamicum is auxotrophic for biotin although biotin ring assembly starting from the precursor pimeloyl-CoA is still functional. It possesses AccBC, the α-subunit of the acyl-carboxylases involved in fatty acid and mycolic acid synthesis, and pyruvate carboxylase as the only biotin-containing proteins. Comparative genome analyses suggested that the putative transport system BioYMN encoded by cg2147, cg2148 and cg2149 might be involved in biotin uptake by C. glutamicum. Results By comparison of global gene expression patterns of cells grown with limiting or excess supply of biotin or with dethiobiotin as supplement replacing biotin revealed that expression of genes coding for enzymes of biotin ring assembly and for the putative uptake system was regulated according to biotin availability. RT-PCR and 5'-RACE experiments demonstrated that the genes bioY, bioM, and bioN are transcribed from one promoter as a single transcript. Biochemical analyses revealed that BioYMN catalyzes the effective uptake of biotin with a concentration of 60 nM biotin supporting a half-maximal transport rate. Maximal biotin uptake rates were at least five fold higher in biotin-limited cells as compared to cells grown with excess biotin. Overexpression of bioYMN led to an at least 50 fold higher biotin uptake rate as compared to the empty vector control. Overproduction of BioYMN alleviated biotin limitation and interfered with triggering L-glutamate production by biotin limitation. Conclusions The operon bioYMN from C. glutamicum was shown to be induced by biotin limitation. Transport assays with radio-labeled biotin revealed that BioYMN functions as a biotin uptake system. Overexpression of bioYMN affected L-glutamate production triggered by biotin limitation. PMID:22243621

Plankton copper requirements and uptake in the subarctic Northeast Pacific Ocean

NASA Astrophysics Data System (ADS)

Semeniuk, David M.; Cullen, Jay T.; Johnson, W. Keith; Gagnon, Katie; Ruth, Thomas J.; Maldonado, Maria T.

2009-07-01

We undertook the first measurements of metabolic Cu requirements (net Cu:C assimilation ratios) and steady-state Cu uptake rates (ρCu ss) of natural plankton assemblages in the northeast subarctic Pacific using the short-lived radioisotope 67Cu. Size-fractionated net Cu:C assimilation ratios varied ˜3 fold (1.35-4.21 μmol Cu mol C -1) among the stations along Line P, from high Fe coastal waters to the Fe-limited open ocean. The variability in Cu:C was comparable to biogenic Fe:C ratios in this region. As previously observed for Fe uptake, the bacterial size class accounted for half of the total particulate ρCu ss. Interestingly, carbon biomass-normalized rates of Fe uptake from the siderophore desferrioxamine B (DFB) (ρFe DFB; a physiological proxy for Fe-limitation) by the >20 μm size class were positively correlated with the intracellular net Cu:C assimilation ratios in this size class, suggesting that intracellular Cu requirements for large phytoplankton respond to increased Fe-limitation. At Fe-limited Ocean Station Papa (OSP), we performed short-term Cu uptake (ρCu L) assays to determine the relative bioavailability of Cu bound to natural and synthetic ligands. Like the volumetric ρCu ss measured along Line P, the bacterial size class was responsible for at least 50% of the total ρCu L. Uptake rates of Cu from the various organic complexes suggest that Cu uptake was controlled by the oxidation state of the metal and by the metal:ligand concentration ratio, rather than the concentration of inorganic species of Cu in solution. Collectively, these data suggest that Cu likely plays an important role in the physiology of natural plankton communities beyond the toxicological effects studied previously.

Urea Uptake and Carbon Fixation by Marine Pelagic Bacteria and Archaea during the Arctic Summer and Winter Seasons

PubMed Central

Connelly, Tara L.; Baer, Steven E.; Cooper, Joshua T.; Bronk, Deborah A.

2014-01-01

How Arctic climate change might translate into alterations of biogeochemical cycles of carbon (C) and nitrogen (N) with respect to inorganic and organic N utilization is not well understood. This study combined 15N uptake rate measurements for ammonium, nitrate, and urea with 15N- and 13C-based DNA stable-isotope probing (SIP). The objective was to identify active bacterial and archeal plankton and their role in N and C uptake during the Arctic summer and winter seasons. We hypothesized that bacteria and archaea would successfully compete for nitrate and urea during the Arctic winter but not during the summer, when phytoplankton dominate the uptake of these nitrogen sources. Samples were collected at a coastal station near Barrow, AK, during August and January. During both seasons, ammonium uptake rates were greater than those for nitrate or urea, and nitrate uptake rates remained lower than those for ammonium or urea. SIP experiments indicated a strong seasonal shift of bacterial and archaeal N utilization from ammonium during the summer to urea during the winter but did not support a similar seasonal pattern of nitrate utilization. Analysis of 16S rRNA gene sequences obtained from each SIP fraction implicated marine group I Crenarchaeota (MGIC) as well as Betaproteobacteria, Firmicutes, SAR11, and SAR324 in N uptake from urea during the winter. Similarly, 13C SIP data suggested dark carbon fixation for MGIC, as well as for several proteobacterial lineages and the Firmicutes. These data are consistent with urea-fueled nitrification by polar archaea and bacteria, which may be advantageous under dark conditions. PMID:25063662

Characterization of the biotin uptake system encoded by the biotin-inducible bioYMN operon of Corynebacterium glutamicum.

PubMed

Schneider, Jens; Peters-Wendisch, Petra; Stansen, K Corinna; Götker, Susanne; Maximow, Stanislav; Krämer, Reinhard; Wendisch, Volker F

2012-01-13

The amino acid-producing Gram-positive Corynebacterium glutamicum is auxotrophic for biotin although biotin ring assembly starting from the precursor pimeloyl-CoA is still functional. It possesses AccBC, the α-subunit of the acyl-carboxylases involved in fatty acid and mycolic acid synthesis, and pyruvate carboxylase as the only biotin-containing proteins. Comparative genome analyses suggested that the putative transport system BioYMN encoded by cg2147, cg2148 and cg2149 might be involved in biotin uptake by C. glutamicum. By comparison of global gene expression patterns of cells grown with limiting or excess supply of biotin or with dethiobiotin as supplement replacing biotin revealed that expression of genes coding for enzymes of biotin ring assembly and for the putative uptake system was regulated according to biotin availability. RT-PCR and 5'-RACE experiments demonstrated that the genes bioY, bioM, and bioN are transcribed from one promoter as a single transcript. Biochemical analyses revealed that BioYMN catalyzes the effective uptake of biotin with a concentration of 60 nM biotin supporting a half-maximal transport rate. Maximal biotin uptake rates were at least five fold higher in biotin-limited cells as compared to cells grown with excess biotin. Overexpression of bioYMN led to an at least 50 fold higher biotin uptake rate as compared to the empty vector control. Overproduction of BioYMN alleviated biotin limitation and interfered with triggering L-glutamate production by biotin limitation. The operon bioYMN from C. glutamicum was shown to be induced by biotin limitation. Transport assays with radio-labeled biotin revealed that BioYMN functions as a biotin uptake system. Overexpression of bioYMN affected L-glutamate production triggered by biotin limitation.

Uptake routes of tumor-antigen MAGE-A3 by dendritic cells determine priming of naïve T-cell subtypes.

PubMed

Moeller, Ines; Spagnoli, Giulio C; Finke, Jürgen; Veelken, Hendrik; Houet, Leonora

2012-11-01

Induction of tumor-antigen-specific T cells in active cancer immunotherapy is generally difficult due to the very low anti-tumoral precursor cytotoxic T cells. By improving tumor-antigen uptake and presentation by dendritic cells (DCs), this problem can be overcome. Focusing on MAGE-A3 protein, frequently expressed in many types of tumors, we analyzed different DC-uptake routes after additional coating the recombinant MAGE-A3 protein with either a specific monoclonal antibody or an immune complex formulation. Opsonization of the protein with antibody resulted in increased DC-uptake compared to the uncoated rhMAGE-A3 protein. This was partly due to Fcγ receptor-dependent internalization. However, unspecific antigen internalization via macropinocytosis also played a role. When analyzing DC-uptake of MAGE-A3 antigen expressed in multiple myeloma cell line U266, pretreatment with proteasome inhibitor bortezomib resulted in increased apoptosis compared to γ-irradiation. Bortezomib-mediated immunogenic apoptosis, characterized by elevated surface expression of hsp90, triggered higher phagocytosis of U266 cells by DCs involving specific DC-derived receptors. We further investigated the impact of antigen delivery on T-cell priming. Induction of CD8(+) T-cell response was favored by stimulating naïve T cells with either antibody-opsonized MAGE-A3 protein or with the bortezomib-pretreated U266 cells, indicating that receptor-mediated uptake favors cross-presentation of antigens. In contrast, CD4(+) T cells were preferentially induced after stimulation with the uncoated protein or protein in the immune complex, both antigen formulations were preferentially internalized by DCs via macropinocytosis. In summary, receptor-mediated DC-uptake mechanisms favored the induction of CD8(+) T cells, relevant for clinical anti-tumor response.

Exploratory clinical trial of (4S)-4-(3-[18F]fluoropropyl)-L-glutamate for imaging xC- transporter using positron emission tomography in patients with non-small cell lung or breast cancer.

PubMed

Baek, Sora; Choi, Chang-Min; Ahn, Sei Hyun; Lee, Jong Won; Gong, Gyungyub; Ryu, Jin-Sook; Oh, Seung Jun; Bacher-Stier, Claudia; Fels, Lüder; Koglin, Norman; Hultsch, Christina; Schatz, Christoph A; Dinkelborg, Ludger M; Mittra, Erik S; Gambhir, Sanjiv S; Moon, Dae Hyuk

2012-10-01

(4S)-4-(3-[(18)F]fluoropropyl)-l-glutamate (BAY 94-9392, alias [(18)F]FSPG) is a new tracer to image x(C)(-) transporter activity with positron emission tomography (PET). We aimed to explore the tumor detection rate of [(18)F]FSPG in patients relative to 2-[(18)F]fluoro-2-deoxyglucose ([(18)F]FDG). The correlation of [(18)F]FSPG uptake with immunohistochemical expression of x(C)(-) transporter and CD44, which stabilizes the xCT subunit of system x(C)(-), was also analyzed. Patients with non-small cell lung cancer (NSCLC, n = 10) or breast cancer (n = 5) who had a positive [(18)F]FDG uptake were included in this exploratory study. PET images were acquired following injection of approximately 300 MBq [(18)F]FSPG. Immunohistochemistry was done using xCT- and CD44-specific antibody. [(18)F]FSPG PET showed high uptake in the kidney and pancreas with rapid blood clearance. [(18)F]FSPG identified all 10 NSCLC and three of the five breast cancer lesions that were confirmed by pathology. [(18)F]FSPG detected 59 of 67 (88%) [(18)F]FDG lesions in NSCLC, and 30 of 73 (41%) in breast cancer. Seven lesions were additionally detected only on [(18)F]FSPG in NSCLC. The tumor-to-blood pool standardized uptake value (SUV) ratio was not significantly different from that of [(18)F]FDG in NSCLC; however, in breast cancer, it was significantly lower (P < 0.05). The maximum SUV of [(18)F]FSPG correlated significantly with the intensity of immunohistochemical staining of x(C)(-) transporter and CD44 (P < 0.01). [(18)F]FSPG seems to be a promising tracer with a relatively high cancer detection rate in patients with NSCLC. [(18)F]FSPG PET may assess x(C)(-) transporter activity in patients with cancer.

Effects of prolonged drought stress on Scots pine seedling carbon allocation.

PubMed

Aaltonen, Heidi; Lindén, Aki; Heinonsalo, Jussi; Biasi, Christina; Pumpanen, Jukka

2017-04-01

As the number of drought occurrences has been predicted to increase with increasing temperatures, it is believed that boreal forests will become particularly vulnerable to decreased growth and increased tree mortality caused by the hydraulic failure, carbon starvation and vulnerability to pests following these. Although drought-affected trees are known to have stunted growth, as well as increased allocation of carbon to roots, still not enough is known about the ways in which trees can acclimate to drought. We studied how drought stress affects belowground and aboveground carbon dynamics, as well as nitrogen uptake, in Scots pine (Pinus sylvestris L.) seedlings exposed to prolonged drought. Overall 40 Scots pine seedlings were divided into control and drought treatments over two growing seasons. Seedlings were pulse-labelled with 13CO2 and litter bags containing 15N-labelled root biomass, and these were used to follow nutrient uptake of trees. We determined photosynthesis, biomass distribution, root and rhizosphere respiration, water potential, leaf osmolalities and carbon and nitrogen assimilation patterns in both treatments. The photosynthetic rate of the drought-induced seedlings did not decrease compared to the control group, the maximum leaf specific photosynthetic rate being 0.058 and 0.045 µmol g-1 s-1 for the drought and control treatments, respectively. The effects of drought were, however, observed as lower water potentials, increased osmolalities as well as decreased growth and greater fine root-to-shoot ratio in the drought-treated seedlings. We also observed improved uptake of labelled nitrogen from soil to needles in the drought-treated seedlings. The results indicate acclimation of seedlings to long-term drought by aiming to retain sufficient water uptake with adequate allocation to roots and root-associated mycorrhizal fungi. The plants seem to control water potential with osmolysis, for which sufficient photosynthetic capability is needed. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Concepts of skin protection: considerations for the evaluation and terminology of the performance of skin protective equipment.

PubMed

Brouwer, Derk H; Aitken, Robert J; Oppl, Reinhard; Cherrie, John W

2005-09-01

This article proposes a common language for better understanding processes involved in dermal exposure and skin protection. A conceptual model has been developed that systematically describes the transport of agent mass from sources, eventually resulting in "loading" of the skin surface or the skin contaminant layer. In view of a harmonized glossary of exposure terminology this is considered the exposure surface. Loading is defined as agent mass present in this layer divided by the exposure surface area. Skin protective equipment (SPE) is meant to reduce uptake, that is, an agent crosses the absorption barrier of the skin, by intervening in the processes of loading the exposure surface; however, the design of the equipment may fail to cover skin surface entirely. In addition, part of the mass intercepted by the SPE may reach the skin surface either by permeation, penetration, or by transfer when touching the contaminated exterior of the SPE. Evaluation of SPE performance has earlier focused on chemical resistance performance testing for permeation, penetration, or degradation of SPE-materials. In use-scenario practice, however, all processes will occur concurrently. Thus, SPE field performance evaluation including user-SPE interaction complementary to material testing is warranted. Results of laboratory testing for SPE-materials are reported as substance-specific breakthrough times and permeation rates. SPE field performance should be evaluated for reduction of either uptake or parameters that reflect the outcome of dermal exposure. Ideally, this should be based on the results of intervention-type workplace studies, for (e.g., assessment of exposure loading). The level of reduction can be expressed as a protection factor (ratio without/with SPE) for different parameters of dermal exposure or uptake. It is concluded that for evaluation of SPE-type performance, generic protection factors can be derived for substance-independent processes (e.g., reduction of exposure loading) but not for substance-specific reduction of uptake.

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.

Effect of pH and calcium on short-term NO3- fluxes in roots of barley seedlings

NASA Technical Reports Server (NTRS)

Aslam, M.; Travis, R. L.; Huffaker, R. C.

1995-01-01

The effect of pH and Ca2+ on net NO3- uptake, influx, and efflux by intact roots of barley (Hordeum vulgare L.) seedlings was studied. Seedlings were induced with NO3- or NO2-. Net NO3- uptake and efflux, respectively, were determined by following its depletion from, and accumulation in, the external solution. Since roots of both uninduced and NO2(-)-induced seedlings contain little internal NO3- initial net uptake rates are equivalent to influx (M. Aslam, R.L. Travis, R.C. Huffaker [1994] Plant Physiol 106: 1293-1301). NO3-, uptake (influx) by these roots was little affected at acidic pH. In contrast, in NO3(-)-induced roots, which accumulate NO3-, net uptake rates decreased in response to acidic pH. Under these conditions, NO3- efflux was stimulated and was a function of root NO3- concentration. Conversely, at basic pH, NO3- uptake by NO3- and NO2(-)-induced and uninduced roots decreased, apparently because of the inhibition of influx. Calcium had little effect on NO3- uptake (influx) by NO2(-)-induced roots at either pH 3 or 6. However, in NO3(-)-induced roots, lack of Ca2+ at pH 3 significantly decreased net NO3- uptake and stimulated efflux. The results indicate that at acidic pH the decrease in net NO3- uptake is due to the stimulation of efflux, whereas at basic pH, it is due to the inhibition of influx.

Stimulatory effect of insulin on glucose uptake by muscle involves the central nervous system in insulin-sensitive mice.

PubMed

Coomans, Claudia P; Biermasz, Nienke R; Geerling, Janine J; Guigas, Bruno; Rensen, Patrick C N; Havekes, Louis M; Romijn, Johannes A

2011-12-01

Insulin inhibits endogenous glucose production (EGP) and stimulates glucose uptake in peripheral tissues. Hypothalamic insulin signaling is required for the inhibitory effects of insulin on EGP. We examined the contribution of central insulin signaling on circulating insulin-stimulated tissue-specific glucose uptake. Tolbutamide, an inhibitor of ATP-sensitive K(+) channels (K(ATP) channels), or vehicle was infused into the lateral ventricle in the basal state and during hyperinsulinemic-euglycemic conditions in postabsorptive, chow-fed C57Bl/6J mice and in postabsorptive C57Bl/6J mice with diet-induced obesity. Whole-body glucose uptake was measured by d-[(14)C]glucose kinetics and tissue-specific glucose uptake by 2-deoxy-d-[(3)H]glucose uptake. During clamp conditions, intracerebroventricular administration of tolbutamide impaired the ability of insulin to inhibit EGP by ∼20%. In addition, intracerebroventricular tolbutamide diminished insulin-stimulated glucose uptake in muscle (by ∼59%) but not in heart or adipose tissue. In contrast, in insulin-resistant mice with diet-induced obesity, intracerebroventricular tolbutamide did not alter the effects of insulin during clamp conditions on EGP or glucose uptake by muscle. Insulin stimulates glucose uptake in muscle in part through effects via K(ATP) channels in the central nervous system, in analogy with the inhibitory effects of insulin on EGP. High-fat diet-induced obesity abolished the central effects of insulin on liver and muscle. These observations stress the role of central insulin resistance in the pathophysiology of diet-induced insulin resistance.

From air to clothing: characterizing the accumulation of semi-volatile organic compounds to fabrics in indoor environments.

PubMed

Saini, A; Okeme, J O; Mark Parnis, J; McQueen, R H; Diamond, M L

2017-05-01

Uptake kinetics of semi-volatile organic compounds (SVOCs) present indoors, namely phthalates and halogenated flame retardants (HFRs), were characterized for cellulose-based cotton and rayon fabrics. Cotton and rayon showed similar accumulation of gas- and particle-phase SVOCs, when normalized to planar surface area. Accumulation was 3-10 times greater by rayon than cotton, when normalized to Brunauer-Emmett-Teller (BET) specific surface area which suggests that cotton could have a longer linear uptake phase than rayon. Linear uptake rates of eight consistently detected HFRs over 56 days of 0.35-0.92 m 3 /day.dm 2 planar surface area and mass transfer coefficients of 1.5-3.8 m/h were statistically similar for cotton and rayon and similar to those for uptake to passive air sampling media. These results suggest air-side controlled uptake and that, on average, 2 m 2 of clothing typically worn by a person would sequester the equivalent of the chemical content in 100 m 3 of air per day. Distribution coefficients between fabric and air (K') ranged from 6.5 to 7.7 (log K') and were within the range of partition coefficients measured for selected phthalates as reported in the literature. The distribution coefficients were similar for low molecular weight HFRs, and up to two orders of magnitude lower than the equilibrium partition coefficients estimated using the COSMO-RS model. Based on the COSMO-RS model, time to reach 95% of equilibrium for PBDEs between fabric and gas-phase compounds ranged from 0.1 to >10 years for low to high molecular weight HFRs. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The KCNQ1-KCNE2 K+ channel is required for adequate thyroid I− uptake

PubMed Central

Purtell, Kerry; Paroder-Belenitsky, Monika; Reyna-Neyra, Andrea; Nicola, Juan P.; Koba, Wade; Fine, Eugene; Carrasco, Nancy; Abbott, Geoffrey W.

2012-01-01

The KCNQ1 α subunit and the KCNE2 β subunit form a potassium channel in thyroid epithelial cells. Genetic disruption of KCNQ1-KCNE2 causes hypothyroidism in mice, resulting in cardiac hypertrophy, dwarfism, alopecia, and prenatal mortality. Here, we investigated the mechanistic requirement for KCNQ1-KCNE2 in thyroid hormone biosynthesis, utilizing whole-animal dynamic positron emission tomography. The KCNQ1-specific antagonist (−)-[3R,4S]-chromanol 293B (C293B) significantly impaired thyroid cell I− uptake, which is mediated by the Na+/I− symporter (NIS), in vivo (dSUV/dt: vehicle, 0.028±0.004 min−1; 10 mg/kg C293B, 0.009±0.006 min−1) and in vitro (EC50: 99±10 μM C293B). Na+-dependent nicotinate uptake by SMCT, however, was unaffected. Kcne2 deletion did not alter the balance of free vs. thyroglobulin-bound I− in the thyroid (distinguished using ClO4−, a competitive inhibitor of NIS), indicating that KCNQ1-KCNE2 is not required for Duox/TPO-mediated I− organification. However, Kcne2 deletion doubled the rate of free I− efflux from the thyroid following ClO4− injection, a NIS-independent process. Thus, KCNQ1-KCNE2 is necessary for adequate thyroid cell I− uptake, the most likely explanation being that it is prerequisite for adequate NIS activity.—Purtell, K., Paroder-Belenitsky, M., Reyna-Neyra, A., Nicola, J. P., Koba, W., Fine, E., Carrasco, N., Abbott, G. W. The KCNQ1-KCNE2 K+ channel is required for adequate thyroid I− uptake. PMID:22549510

Uptake of oleate by isolated rat adipocytes is mediated by a 40-kDa plasma membrane fatty acid binding protein closely related to that in liver and gut

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

Schwieterman, W.; Sorrentino, D.; Potter, B.J.

1988-01-01

A portion of the hepatocellular uptake of nonesterified long-chain fatty acids is mediated by a specific 40-kDa plasma membrane fatty acid binding protein, which has also been isolated from the gut. To investigate whether a similar transport process exists in other tissues with high transmembrane fatty acid fluxes, initial rates (V/sub O/) of (/sup 3/H)-oleate uptake into isolated rat adipocytes were studied as a function of the concentration of unbound (/sup 3/H)oleate in the medium. V/sub O/ reached a maximum as the concentration of unbound oleate was increased and was significantly inhibited both by phloretin and by prior incubation ofmore » the cells with Pronase. A rabbit antibody to the rat liver plasma membrane fatty acid binding protein inhibited adipocyte fatty acid uptake by up to 63% in dose-dependent fashion. Inhibition was noncompetitive; at an immunoglobulin concentration of 250 ..mu..g/ml V/sub max/ was reduced from 2480 /plus minus/ 160 to 1870 /plus minus/ 80 pmol/min per 5 /times/ 10/sup 4/ adipocytes, with no change in K/sub m/. A basic kDa adipocyte plasma membrane fatty acid binding protein, isolated from crude adipocyte plasma membrane fractions, reacted strongly in both agar gel diffusion and electrophoretic blots with the antibody raised against the corresponding hepatic plasma membrane protein. These data indicate that the uptake of oleate by rat adipocytes is mediated by a 40-kDa plasma membrane fatty acid binding protein closely related to that in liver and gut.« less

Prostate and Colorectal Cancer Screening Uptake among US and Foreign-Born Males: Evidence from the 2015 NHIS Survey.

PubMed

Ilunga Tshiswaka, Daudet; Donley, Tiffany; Okafor, Anthony; Memiah, Peter; Mbizo, Justice

2017-06-01

Research suggests that prostate and colorectal cancers disproportionately affect men in the US, but little is known about the determinants of prostate-specific antigen (PSA) and colorectal cancer (CRC) screening uptake among US and foreign-born males. The purpose of this study was to investigate what factors influence prostate and colorectal cancer screening uptake among US-native born and foreign-born men. Using the 2015 National Health Interview Survey, we conducted bivariate and multivariate analyses to highlight factors associated with the uptake of prostate and colorectal cancer screening among US-native born and foreign-born men. The sample size consisted of 5651 men respondents, with the mean age of 59.7 years (SD = 12.1). Of these, more than two-fifths (42%) were aged 50-64 years old. With respect to race/ethnicity, the sample was predominantly non-Hispanic Whites (65.5%), 863 (15.6%) Hispanics, and 710 (12.4%) Blacks. Our analysis found higher rates of both US-born and foreign-born men aged 65 years or older, who had either a PSA or CRC screening tests than those aged <65 years. Results of the general multivariate model suggest that men under 50 years old, US-born and foreign-born alike, are statistically significantly less likely to have prostate or colorectal cancer screenings than men aged 65 years or above. This study highlights the influencing factors that encourage or discourage PSA and CRC screening uptake between US-native born and foreign-born men. The results of this inquiry provide an evidence-based blueprint for policymakers and interventionists seeking to address prostate and colorectal cancer among men.

Temperature influences on the accumulation and elimination of mercury in a freshwater cladoceran, Daphnia magna.

PubMed

Tsui, Martin T K; Wang, Wen-Xiong

2004-12-10

Temperature is an important environmental variable affecting the physiology and metabolism of aquatic invertebrates and can potentially affect the rate and pathway of the uptake and elimination of contaminants. In this study, we studied the effects of the ambient temperature on the uptake (from water and food) and elimination of inorganic mercury [Hg(II)] and methymercury (MeHg) in a freshwater cladoceran, Daphnia magna, in the laboratory. At different temperatures (i.e., 14, 19 and 24 degrees C), the assimilation efficiencies of both Hg species from ingested alga were not significantly different while the dissolved uptake rates were 32 and 73% lower at 14 degrees C than at 24 degrees C for Hg(II) and MeHg, respectively. The reduced uptake rates of Hg(II) at 14 degrees C could be adequately explained by the reduced filtration rate (40% reduction), but for MeHg, the reduced filtration rate could not completely explain reduction in MeHg uptake rate. Despite the elimination rates of both Hg compounds not being affected by the temperature, the relative importance of different routes of Hg loss (i.e., excretion, egestion, molting and reproduction) was significantly different at various temperatures. The relative importance of excretion to MeHg loss increased from 24 to 14 degrees C (i.e., 52 to 85% of Hg loss) while that of reproduction to MeHg loss decreased from 43 to 11% simultaneously. Using a kinetic model, we showed that the fraction of MeHg accumulated in the daphnids coming from the dietary phase was higher at lower temperature, while there was increased accumulation of both Hg(II) and MeHg in the daphnids at higher temperatures. Nevertheless, the trophic transfer potentials for both Hg species in this algae-daphnids food chain were not influenced by the temperature.