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Sample records for acid uptake systems

  1. Amino-acid uptake by mussels, Mytilus edulis, from natural sea water in a flow-through system

    NASA Astrophysics Data System (ADS)

    Siebers, D.; Winkler, A.

    1984-03-01

    Natural Wadden Sea water taken from the North Sea (island of Sylt) was pumped at rates of 150 and 300 l h-1 through a 4 l plexiglass tube mounted on a wooden tripod on the beach. The tube was densely filled with numerous cleaned mussels, Mytilus edulis. HPLC analysis of sea water showed that total dissolved amino acids are patchily distributed, varying by 100 % within 15 min, though proportions of individual amino acids were remarkably constant. Total amino-acid concentrations were 1528±669 nM (N=3) in October 1983 and 1198±597 nM (N=7) in July 1984. Samples taken at the entrance and the outlet of the experimental mussel bed revealed that the mussels had taken up 29 to 66 % of the amino acids dissolved in sea water. Uptake was observed for all amino acids detected in the chromatograms. 78 % of uptake resulted from the 5 most concentrated amino acids: serine, alanine, glycine/threonine, ornithine, aspartic acid. The nutritional profit obtained from uptake of dissolved amino acids amounted to 12 % (N=5, range 5 23 %, flow rate 150 l h-1) and to 24 % (N=3, range 13 38 %, flow rate 300 l h-1) of metabolic rate. The present data suggest that amino-acid concentration predominantly determines the magnitude of the nutritional profit obtained from uptake, and to a smaller extent the flow rate. These findings are in contrast to results of previous studies on Asterias rubens, interacting in small-volume closed systems with the natural bacterial sea water flora (Siebers, 1982). In these experiments, bacteria, due to rapid uptake, outcompeted the sea stars in absorption of dissolved amino acids. The present results suggest that bivalve mussels, can, due to their large gill surface areas and the great amounts of water pumped through their mantle cavity, successfully compete with bacteria in uptake of dissolved organic matter. Mussels, therefore, suggestedly play an important role in cycling dissolved organic matter.

  2. Osmotically inducible uptake of betaine via amino acid transport system A in SV-3T3 cells.

    PubMed

    Petronini, P G; De Angelis, E; Borghetti, A F; Wheeler, K P

    1994-05-15

    The osmotically inducible uptake of betaine (NNN-trimethylglycine) by SV-3T3 cells has been studied and compared with the similar process in MDCK cells. Betaine uptake by SV-3T3 cells could be described in terms of a saturable, Na(+)-dependent, component plus a small non-saturable, Na(+)-independent, component. Transport was active, producing considerable accumulation of betaine in the cells. After exposure of the cells to hypertonic conditions for 6 h, there was a marked increase in betaine uptake. Kinetic analysis indicated that this increase resulted from an increase in the Vmax. value of the saturable component, from about 88 to 185 nmol of betaine/5 min per mg of protein, the corresponding Km values of about 15 and 10 mM not being significantly different. This induction of transport activity was detectable only after about 2 h exposure of the cells to hypertonic medium, closely paralleling an induction of influx of N-methylaminoisobutyric acid, and was prevented by the presence of cycloheximide. Betaine influx was markedly inhibited by several neutral amino acids, particularly those transported by system A, such as N-methylaminoisobutyric acid and the imino acid proline. A high concentration (25 mM) of betaine also significantly inhibited the uptake of proline by SV-3T3 cells. Although very similar results were obtained with MDCK cells, prolonged exposure of cells to hypertonic conditions revealed distinct differences. When the hypertonic incubation was extended from 6 h to 24 h, betaine transport in SV-3T3 cells either remained the same or decreased, whereas it showed a further marked increase in MDCK cells, and also became sensitive to inhibition by gamma-aminobutyric acid. mRNA for the betaine transporter BGT-1 [Yamauchi, Uchida, Kwon, Preston, Brooks Robey, Garcia-Perez, Burg and Handler (1992) J. Biol. Chem. 267, 649-652] was detectable in MDCK cells exposed to hypertonic medium for 24 h, but not in SV-3T3 cells under any conditions. It is concluded that

  3. Glycinergic-Fipronil Uptake Is Mediated by an Amino Acid Carrier System and Induces the Expression of Amino Acid Transporter Genes in Ricinus communis Seedlings.

    PubMed

    Xie, Yun; Zhao, Jun-Long; Wang, Chuan-Wei; Yu, Ai-Xin; Liu, Niu; Chen, Li; Lin, Fei; Xu, Han-Hong

    2016-05-18

    Phloem-mobile insecticides are efficient for piercing and sucking insect control. Introduction of sugar or amino acid groups to the parent compound can improve the phloem mobility of insecticides, so a glycinergic-fipronil conjugate (GlyF), 2-(3-(3-cyano-1-(2,6-dichloro-4-(trifluoromethyl)phenyl)-4-((trifluoromethyl)sulfinyl)-1H-pyrazole-5-yl)ureido) acetic acid, was designed and synthesized. Although the "Kleier model" predicted that this conjugate is not phloem mobile, GlyF can be continually detected during a 5 h collection of Ricinus communis phloem sap. Furthermore, an R. communis seedling cotyledon disk uptake experiment demonstrates that the uptake of GlyF is sensitive to pH, carbonyl cyanide m-chlorophenylhydrazone (CCCP), temperature, and p-chloromercuribenzenesulfonic acid (pCMBS) and is likely mediated by amino acid carrier system. To explore the roles of amino acid transporters (AATs) in GlyF uptake, a total of 62 AAT genes were identified from the R. communis genome in silico. Phylogenetic analysis revealed that AATs in R. communis were organized into the ATF (amino acid transporter) and APC (amino acid, polyaminem and choline transporter) superfamilies, with five subfamilies in ATF and two in APC. Furthermore, the expression profiles of 20 abundantly expressed AATs (cycle threshold (Ct) values <27) were analyzed at 1, 3, and 6 h after GlyF treatment by RT-qPCR. The results demonstrated that expression levels of four AAT genes, RcLHT6, RcANT15, RcProT2, and RcCAT2, were induced by the GlyF treatment in R. communis seedlings. On the basis of the observation that the expression profile of the four candidate genes is similar to the time course observation for GlyF foliar disk uptake, it is suggested that those four genes are possible candidates involved in the uptake of GlyF. These results contribute to a better understanding of the mechanism of GlyF uptake as well as phloem loading from a molecular biology perspective and facilitate functional

  4. Fatty acid uptake in normal human myocardium

    SciTech Connect

    Vyska, K.; Meyer, W.; Stremmel, W.; Notohamiprodjo, G.; Minami, K.; Machulla, H.J.; Gleichmann, U.; Meyer, H.; Koerfer, R. )

    1991-09-01

    Fatty acid binding protein has been found in rat aortic endothelial cell membrane. It has been identified to be a 40-kDa protein that corresponds to a 40-kDa fatty acid binding protein with high affinity for a variety of long chain fatty acids isolated from rat heart myocytes. It is proposed that this endothelial membrane fatty acid binding protein might mediate the myocardial uptake of fatty acids. For evaluation of this hypothesis in vivo, influx kinetics of tracer-labeled fatty acids was examined in 15 normal subjects by scintigraphic techniques. Variation of the plasma fatty acid concentration and plasma perfusion rate has been achieved by modulation of nutrition state and exercise conditions. The clinical results suggest that the myocardial fatty acid influx rate is saturable by increasing fatty acid plasma concentration as well as by increasing plasma flow. For analysis of these data, functional relations describing fatty acid transport from plasma into myocardial tissue in the presence and absence of an unstirred layer were developed. The fitting of these relations to experimental data indicate that the free fatty acid influx into myocardial tissue reveals the criteria of a reaction on a capillary surface in the vicinity of flowing plasma but not of a reaction in extravascular space or in an unstirred layer and that the fatty acid influx into normal myocardium is a saturable process that is characterized by the quantity corresponding to the Michaelis-Menten constant, Km, and the maximal velocity, Vmax, 0.24 {plus minus} 0.024 mumol/g and 0.37 {plus minus} 0.013 mumol/g(g.min), respectively. These data are compatible with a nondiffusional uptake process mediated by the initial interaction of fatty acids with the 40-kDa membrane fatty acid binding protein of cardiac endothelial cells.

  5. Uptake and distribution of nitrogen from acidic fog within a ponderosa pine (Pinus ponderosa Laws.)/litter/soil system

    SciTech Connect

    Fenn, M.E.; Leininger, T.D.

    1995-11-01

    The magnitude and importance of wet deposition of N in forests of the South Coast (Los Angeles) Air Basin have not been well characterized. We exposed 3-yr-old ponderosa pine (Pinus ponderosa Laws.) seedlings growing in native forest soil to acidic fog treatments (pH 3.1) simulating fog chemistry from a pine forest near Los Angeles, California. Fog solutions contained either {sup 15}NH{sub 4}{sup +}, {sup 15}NO{sub 3}{sup {minus}}, or unlabeled N. The fog treatments were applied in open-top chambers in six 5-hr exposures. Soil treatments within each of the fog exposures were bare soil, soil overlain with L- and F-litter, and soil covered with plastic during the fog events to prevent fogwater from contacting soil. Seedlings were harvested and samples were collected 15 wk after the fog treatments. Uptake of {sup 15}N by roots was by far the dominant pathway for plant assimilation of fog-deposited {sup 15}N. Deposition of N in fog supplied 9.4% and 8.7% of the total N in current-year crown biomass in the litter-overlay and bare-soil treatments, respectively. Total N concentrations in every plant fraction except current-year stems were significantly higher in the bare-soil treatment than in the plastic-covered soil treatment. Less than 5% of the {sup 15}N deposited directly to the seedling crowns was retained by the plants in the covered-soil treatment, whereas 57% of the {sup 15}N deposited to the seedling/litter/soil systems was incorporated into plant biomass. The litter layers retained {sup 15}NH{sub 4}{sup +} more effectively than {sup 15}NH{sub 4}{sup +} more effectively than {sup 15}NO{sub 3}. Data from this study suggest that N deposited from fog may be an important source of N for plant growth in forests of the SCAB where fog occurrence and pollution exposure coincide. 5 refs., 5 figs., 3 tabs.

  6. Uptake of 2, 4-Dichlorophenoxyacetic acid by Pseudomonas fluorescens

    USGS Publications Warehouse

    Wedemeyer, G.A.

    1966-01-01

    WEDEMEYER, GARY (Fish-Pesticide Research Laboratory, Denver, Colo.). Uptake of 2,4-dichlorophenoxyacetic acid by Pseudomonas fluorescens. Appl. Microbiol. 14:486-491. 1966.-Factors influencing the uptake of the sodium salt of 2,4-dichlorophenoxyacetic acid (2,4-D), under conditions in which no net metabolism occurred, were investigated in an effort to determine both the significance of “nonmetabolic” uptake as a potential agent in reducing pesticide levels and the mechanisms involved. Uptake of 2,4-D was affected by pH, temperature, and the presence of other organic and inorganic compounds. Uptake was more pronounced at pH values less than 6, which implies that there may be some interaction between charged groups on the cell and the ionized carboxyl group of 2,4-D. Active transport, carriermediated diffusion, passive diffusion, and adsorption were considered as possible mechanisms. Though uptake was inhibited by glucose, sodium azide, and fluorodinitrobenzene (but not by uranylion), 2,4-D was not accumulated against a concentration gradient, a necessary consequence of an active transport system, nor was isotope counterflow found to occur. Thus, carrier-mediated diffusion was finally precluded, implying that uptake probably occurs by a two-step process: sorption onto the cell wall followed by passive diffusion into the cytoplasm.

  7. Recombinant glucose uptake system

    DOEpatents

    Ingrahm, Lonnie O.; Snoep, Jacob L.; Arfman, Nico

    1997-01-01

    Recombinant organisms are disclosed that contain a pathway for glucose uptake other than the pathway normally utilized by the host cell. In particular, the host cell is one in which glucose transport into the cell normally is coupled to PEP production. This host cell is transformed so that it uses an alternative pathway for glucose transport that is not coupled to PEP production. In a preferred embodiment, the host cell is a bacterium other than Z. mobilis that has been transformed to contain the glf and glk genes of Z. mobilis. By uncoupling glucose transport into the cell from PEP utilization, more PEP is produced for synthesis of products of commercial importance from a given quantity of biomass supplied to the host cells.

  8. Uptake of 2,4-Dichlorophenoxyacetic Acid by Pseudomonas fluorescens

    USGS Publications Warehouse

    Wedemeyer, Gary

    1966-01-01

    Factors influencing the uptake of the sodium salt of 2,4-dichlorophenoxyacetic acid (2,4-D), under conditions in which no net metabolism occurred, were investigated in an effort to determine both the significance of “non-metabolic” uptake as a potential agent in reducing pesticide levels and the mechanisms involved. Uptake of 2,4-D was affected by pH, temperature, and the presence of other organic and inorganic compounds. Uptake was more pronounced at pH values less than 6, which implies that there may be some interaction between charged groups on the cell and the ionized carboxyl group of 2,4-D. Active transport, carrier-mediated diffusion, passive diffusion, and adsorption were considered as possible mechanisms. Though uptake was inhibited by glucose, sodium azide, and fluorodinitrobenzene (but not by uranyl ion), 2,4-D was not accumulated against a concentration gradient, a necessary consequence of an active transport system, nor was isotope counterflow found to occur. Thus, carrier-mediated diffusion was finally precluded, implying that uptake probably occurs by a two-step process: sorption onto the cell wall followed by passive diffusion into the cytoplasm.

  9. Effect of zinc source and picolinic acid on /sup 65/Zn uptake in an in vitro continuous-flow perfusion system for pig and poultry intestinal segments

    SciTech Connect

    Hill, D.A.; Peo, E.R. Jr.; Lewis, A.J.

    1987-10-01

    Twenty weanling pigs and fourteen 9-wk-old broiler chickens were used in three continuous-flow in vitro perfusion experiments using noneverted intestinal sacs to 1) determine differences in /sup 65/Zn absorption due to location within the intestinal tract, 2) evaluate /sup 65/Zn uptake from ZnCl/sub 2/ and Zn-methionine (ZnMet) with or without added picolinic acid (PA) in pig intestinal sacs and 3) evaluate /sup 65/Zn uptake from ZnCl/sub 2/ and ZnMet in chicken intestinal sacs. No differences in /sup 65/Zn uptake due to gut segment position were observed in the pigs. A Zn source x PA interaction was observed for /sup 65/Zn uptake into the pig gut tissue and for /sup 65/Zn uptake to the serosal side of the gut sacs. Total /sup 65/Zn absorption in the pig gut sacs from the two Zn sources was not different, but the addition of a 5 M ratio of PA to Zn depressed /sup 65/Zn absorption. No differences were observed in total /sup 65/Zn absorption or /sup 65/Zn uptake in poultry gut sac tissue. There was, however, greater uptake of /sup 65/Zn from ZnCl/sub 2/ to the serosal side of the sacs than from ZnMet. The data indicate that /sup 65/Zn from ZnCl/sub 2/ and ZnMet is similar in total absorption and that the addition of PA depresses Zn uptake.

  10. Styrene maleic acid micelles as a nanocarrier system for oral anticancer drug delivery – dual uptake through enterocytes and M-cells

    PubMed Central

    Parayath, Neha N; Nehoff, Hayley; Müller, Philipp; Taurin, Sebastien; Greish, Khaled

    2015-01-01

    Drug delivery systems could potentially overcome low bioavailability and gastrointestinal toxicity, which are the major challenges for the development of oral anticancer drugs. Herein, we demonstrate the ability of styrene maleic acid (SMA) nanomicelles encapsulating epirubicin to traverse in vitro and ex vivo models of the intestinal epithelium without affecting the tissue integrity. Further, SMA micelles encapsulating a fluorescent dye dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI) showed twofold higher accumulation in the liver and spleen, 15-fold higher accumulation in the tumor, and sixfold higher accumulation in the lung as compared with the free DiI, following oral administration in a mice xenograft breast cancer model. Additionally, SMA micelles showed colocalization with microfold (M)-cells and accumulation in Peyer’s patches, which together confirms the M-cell mediated uptake and transport of SMA micelles. Our results indicate that SMA micelles, showing dual uptake by enterocytes and M-cells, are a potential tool for safe oral anticancer drug delivery. PMID:26229468

  11. Nucleic acids encoding metal uptake transporters and their uses

    DOEpatents

    Schroeder, Julian I.; Antosiewicz, Danuta M.; Schachtman, Daniel P.; Clemens, Stephan

    1999-01-01

    The invention provides LCT1 nucleic acids which encode metal ion uptake transporters. The invention also provides methods of modulating heavy metal and alkali metal uptake in plants. The methods involve producing transgenic plants comprising a recombinant expression cassette containing an LCT1 nucleic acid linked to a plant promoter.

  12. Cystine and dibasic amino acid uptake by opossum kidney cells

    SciTech Connect

    States, B.; Segal, S. )

    1990-06-01

    The characteristics of the uptake of L-cystine by the continuous opossum kidney cell line, OK, were examined. Uptake of cystine is rapid and, in contrast to other continuous cultured cell lines, these cells retain the cystine/dibasic amino acid transport system which is found in vivo and in freshly isolated kidney tissue. Confluent monolayers of cells also fail to show the presence of the cystine/glutamate transport system present in LLC-PK1 cells, fibroblasts, and cultured hepatocytes. Uptake of cystine occurs via a high-affinity saturable process which is independent of medium sodium concentration. The predominant site of cystine transport is across the apical cell membrane. The intracellular concentration of GSH far exceeds that of cystine with a ratio greater than 100:1 for GSH:cysteine. Incubation of cells for 5 minutes with a physiological level of labelled cystine resulted in the labelling of 66% and 5% of the total intracellular cysteine and glutathione, respectively. The ability of these cells to reflect the shared cystine/dibasic amino acid transport system makes them a suitable model for investigation of the cystine carrier which is altered in human cystinuria.

  13. Characterization of ascorbic acid uptake by isolated rat kidney cells

    SciTech Connect

    Bowers-Komro, D.M.; McCormick, D.B. )

    1991-01-01

    Isolated kidney cells accumulated L(1-14C)ascorbic acid in a time-dependent manner and reached a steady state after 15 min at 37 degrees C. Initial velocity for uptake was over 300 pmol/mg protein per min when cells were separated from the bathing solution using a density gradient established during centrifugation. The uptake process was saturable with an apparent concentration at half maximal uptake of 36 mumols/L. Ascorbate uptake was reduced by metabolic inhibitors and was temperature dependent. Although ascorbic acid is an acid anion at pH 7.4, uptake did not appear to be inhibited by other acid anions such as p-aminohippurate and probenecid; however, involvement of the ion gradient established by Na+, H(+)-adenosine triphosphatase could not be confirmed. Replacing the sodium ion with other monovalent ions reduced the accumulation of ascorbate significantly. Isoascorbic and dehydroascorbic acids inhibited ascorbate uptake (34 and 13 mmol/L, respectively), whereas high concentrations of glucose showed some stimulation. These findings indicated that ascorbic acid is reabsorbed by the kidney in a sodium-dependent active transport process that is not common to other acid anions and has some specificity for the ascorbic acid structure.

  14. Free fatty-acid uptake by isolated rat hepatocytes.

    PubMed

    Renaud, G; Bouma, M E; Foliot, A; Infante, R

    1985-11-01

    In isolated rat hepatocytes, the rate of palmitic acid binding and uptake is directly related to the concentration of free fatty acid (FFA) in the medium. After their entry into the cell, FFA are immediately incorporated into cellular phospholipids and triglycerides and no accumulation of free fatty acids can be demonstrated inside the cell. The rate of free fatty-acid uptake remains unchanged after incubation in a 2 mM KCN containing medium, indicating that in the range of fatty-acid concentrations used in this study, this phenomenon does not require energy. PMID:2421669

  15. Excitatory amino acid-stimulated uptake of /sup 22/Na+ in primary astrocyte cultures

    SciTech Connect

    Kimelberg, H.K.; Pang, S.; Treble, D.H.

    1989-04-01

    In this study we have found that L-glutamic acid, as well as being taken up by a Na+-dependent mechanism, will stimulate the uptake of 22Na+ by primary astrocyte cultures from rat brain in the presence of ouabain. By simultaneously measuring the uptake of 22Na+ and L-3H-glutamate a stoichiometry of 2-3 Na+ per glutamate was measured, implying electrogenic uptake. Increasing the medium K+ concentration to depolarize the cells inhibited L-3H-glutamate uptake, while calculations of the energetics of the observed L-3H-glutamate accumulation also supported an electrogenic mechanism of at least 2 Na+:1 glutamate. In contrast, kinetic analysis of the Na+ dependence of L-3H-glutamate uptake indicated a stoichiometry of Na+ to glutamate of 1:1, but further analysis showed that the stoichiometry cannot be resolved by purely kinetic studies. Studies with glutamate analogs, however, showed that kainic acid was a very effective stimulant of 22Na+ uptake, but 3H-kainic acid showed no Na+ -dependent uptake. Furthermore, while L-3H-glutamate uptake was very sensitive to lowered temperatures, glutamate-stimulated 22Na+ uptake was relatively insensitive. These results indicate that glutamate-stimulated uptake of 22Na+ in primary astrocytes cultures cannot be explained solely by cotransport of Na+ with glutamate, and they suggest that direct kainic acid-type receptor induced stimulation of Na+ uptake also occurs. Since both receptor and uptake effects involve transport of Na+, accurate measurements of the Na+ :glutamate stoichiometry for uptake can only be done using completely specific inhibitors of these 2 systems.

  16. Uptake of Gas-Phase Nitric Acid by Water-Ice Surfaces

    NASA Astrophysics Data System (ADS)

    Ullerstam, M.; Abbatt, J. P.

    2004-05-01

    Nitric acid is a widespread molecule found in the atmosphere. It is mainly removed from the troposphere by wet or dry deposition. In colder regions such as the upper troposphere and tropopause where cirrus clouds are formed nitric acid can also be scavenged by cirrus ice particles. The uptake of gas-phase nitric acid by water-ice films has been re-examined with a coated-wall flow tube coupled to a chemical-ionization mass spectrometer (CIMS) at 228K. Previous flow tube studies of this system have shown little dependence of the uptake over the partial pressure regime studied. In these studies the initial, short-term uptake has been the focus and the long term uptake has not been quantified. In this experimental setup it was possible to study the uptake of nitric acid at lower partial pressures resulting in a more atmospherically appropriate determination of the adsorption isotherm and the long term uptake has also been addressed. Measurement of the initial uptake coefficient representing a lower limit will also be presented. Finally, possible burial of nitric acid into the bulk of the ice during continuous growth of the ice film has been studied. In the atmosphere ice particles will be subject to cycles of evaporation and condensation which could cause the nitric acid to be encapsulated into the particle, especially since the major part of the adsorption has been proven to be irreversible. This could enhance the ice particles capacity of scavenging nitric acid.

  17. The Exocyst Complex Regulates Free Fatty Acid Uptake by Adipocytes

    PubMed Central

    Inoue, Mayumi; Akama, Takeshi; Jiang, Yibin; Chun, Tae-Hwa

    2015-01-01

    The exocyst is an octameric molecular complex that drives vesicle trafficking in adipocytes, a rate-limiting step in insulin-dependent glucose uptake. This study assessed the role of the exocyst complex in regulating free fatty acid (FFA) uptake by adipocytes. Upon differentiating into adipocytes, 3T3-L1 cells acquire the ability to incorporate extracellular FFAs in an insulin-dependent manner. A kinetic assay using fluoresceinated FFA (C12 dodecanoic acid) uptake allows the real-time monitoring of FFA internalization by adipocytes. The insulin-dependent uptake of C12 dodecanoic acid by 3T3-L1 adipocytes is mediated by Akt and phosphatidylinositol 3 (PI3)-kinase. Gene silencing of the exocyst components Exo70 and Sec8 significantly reduced insulin-dependent FFA uptake by adipocytes. Consistent with the roles played by Exo70 and Sec8 in FFA uptake, mCherry-tagged Exo70 and HA-tagged Sec8 partially colocalize with lipid droplets within adipocytes, suggesting their active roles in the development of lipid droplets. Tubulin polymerization was also found to regulate FFA uptake in collaboration with the exocyst complex. This study demonstrates a novel role played by the exocyst complex in the regulation of FFA uptake by adipocytes. PMID:25768116

  18. Effect of Acids on Water Vapor Uptake by Pyrogenic Silica

    PubMed

    Bogdan; Kulmala

    1997-07-01

    Effect of gaseous HCl and HNO3 on the water vapor uptake by pyrogenic silica was studied at different relative humidities (RH) for pure water and different compositions of binary and ternary vapor mixtures. Experiments showed that the ability of silica to uptake water strongly depends on RH and on the type of acids and their concentration in the vapor mixtures. At low acid concentration in the binary mixtures the influence of acids is probably small. Water uptake by silica does not change monotonically with acid concentration: at first it decreases and then starts to grow. However, the presence of acids promotes water uptake, and the effect is very significant at low RH. HCl seems to be more effective acid to enhance water uptake than HNO3 . In the case of ternary mixtures the adsorbed weight of water is a bit larger than that adsorbed from the binary mixtures. Acids are accumulated by silica surface, and the accumulation is larger for nitric acid. PMID:9241208

  19. Umbilical uptake of amino acids in the unstressed fetal lamb.

    PubMed Central

    Lemons, J A; Adcock, E W; Jones, M D; Naughton, M A; Meschia, G; Battaglia, F C

    1976-01-01

    The whole blood concentrations of 22 amino acids were measured in a chronic, unstressed fetal lamb preparations. Samples were taken daily from the umbilical artery, umbilical vein, and maternal artery over the latter quarter of gestation. 73 sets of samples (from the umbilical artery and vein and the maternal artery) from 13 animals were analyzed for amino acid levels. Oxygen contents were determined simultaneously in 48 sets (umbilical artery and vein) to relate fetal oxygen consumption to amino acid uptake via the umbilical circulation. The results indicate that there is no umbilical uptake of the acidic amino acids, glutamate and aspartate; there is, in fact, a net flux of glutamate out of the fetus into the placenta. As both of these amino acids are major constituents of body proteins, the data indicate that they are formed within the fetus. The umbilical uptake of some neutral and basic amino acids (e.g., valine, leucine, isoleucine, arginine, phenylalanine, and tyrosine) is in considerable excess of estimated growth requirements, suggesting that some amino acids undergo extensive transamination and oxidative degradation in the fetus. Finally, the net uptake of nitrogen, carbon, and calories by the growing ovine fetus in the form of amino acids, glucose, and lactate is compared to estimated requirements as determined in previous studies. PMID:1033209

  20. Effect of fulvic acid on neodymium uptake by goethite.

    PubMed

    Armstrong, Christopher R; Wood, Scott A

    2012-12-01

    Experimental studies of the interaction of aqueous neodymium (Nd), Suwannee River fulvic acid (FA), and solid phase goethite were conducted. Results from blank systems (individual Nd and FA), binary systems (Nd-goethite, FA-goethite, and Nd-FA), and ternary systems (Nd-FA-goethite) at 0.1 mol/kg and 25°C are reported. In the binary Nd-goethite system a classic sorption edge is observed, whereby virtually all Nd is removed from solution above the goethite point of zero charge (PZC). Similarly, the binary FA-goethite system exhibits strong FA sorption; However in this system near complete removal of FA from solution is observed below the goethite PZC. In the binary Nd-FA system, both aqueous Nd and FA feature a sharp decrease in concentration at ca. pH 9. Various experiments in the ternary system were conducted. For all concentrations, FA enhanced Nd sorption below the goethite PZC, attributed to the formation of a Type B ternary surface complex (mineral-ligand-metal ion). Notably, the 100 ppm FA ternary system showed anomalously high dissolved Nd in solution above the PZC (i.e., Nd sorption suppression) and a concomitant increase in goethite dissolution (∼9 ppm total Fe(3+) observed above circa pH 9.5). Our results suggest that Nd-FA complexation plays a key role in Nd uptake by goethite, and that this process is largely governed by pH: Whereas at pHs below the goethite PZC, Nd-FA complexation facilitates Nd sorption, above the PZC, and particularly at elevated FA concentrations, the formation of aqueous Nd-FA complexes suppresses Nd removal. Moreover, under these conditions, goethite dissolution may also play a role in mitigating Nd uptake by goethite. PMID:22958855

  1. Sialic Acid Uptake Is Necessary for Virulence of Pasteurella multocida in turkeys

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many pathogenic bacteria employ systems to incorporate sialic acid into their membranes as a means of protection against host defense mechanisms. Pasteurella multocida is an opportunistic pathogen which causes diseases of economic importance in a wide range of animal species and sialic acid uptake p...

  2. Free Fatty Acid Uptake in Humans With CD36 Deficiency

    PubMed Central

    Hames, Kazanna C.; Vella, Adrian; Kemp, Bradley J.

    2014-01-01

    Animal models have demonstrated that CD36 facilitates cell membrane free fatty acid (FFA) transport, but its role in human metabolism is not well understood. We measured heart, liver, adipose (three depots), and muscle (truncal postural and thigh locomotive) FFA uptake using [11C]palmitate positron emission tomography (PET) scans in a family of five carrying the Pro90Ser CD36 mutation (2 homozygotes had no CD36) and matched control volunteers. PET scans were done under conditions of suppressed and slightly increased palmitate concentrations. During suppressed palmitate conditions, muscle and adipose palmitate uptake were markedly reduced in homozygotes but not heterozygotes for the Pro90Ser CD36 mutation, whereas when palmitate concentration was slightly increased, uptake in muscle and adipose did not differ between control subjects and homozygous family members. Hepatic FFA uptake was similar in all participants regardless of palmitate concentrations, whereas myocardial FFA uptake was diminished in the Pro90Ser homozygotes during both suppressed and increased palmitate conditions. We conclude that CD36 1) facilitates FFA transport into muscle and adipose tissue in humans when extracellular concentrations are reduced but not when they are modestly elevated, 2) is not rate limiting for hepatic FFA uptake, and 3) is needed for normal cardiac FFA uptake over a range of FFA concentrations from low to slightly elevated. PMID:24917573

  3. Uptake of benzoic acid and chloro-substituted benzoic acids by alcaligenes denitrificans BRI 3010 and BRI 6011

    SciTech Connect

    Miguez, C.B.; Ingram, J.M.; MacLeod, R.A.

    1995-12-01

    The mechanism of uptake of benzoic and 2,4-dichlorobenzoic acid (2,4-DCBA) by Alcaligenes denitrificans BRI 3010 and BRI 6011 and Pseudomonas sp. strain B13, three organisms capable of degrading isomers of chlorinated benzoic acids, was investigated. In all three organisms, uptake of benzoic acid was inducible. For benzoic acid uptake into BRI 3010, monophasic saturation kinetics with apparent K{sub m} and V{sub max} values of 1.4 {mu}M and 3.2 nmol/min/mg of cell dry weight, respectively, were obtained. For BRI 6011, biphasic saturation kinetics were observed, suggesting presence of two uptake systems for benzoic acid with distinct K{sub m} (0.72 and 5.3 {mu}M) and V{sub max} (3.3 and 4.6 nmol/min/mg of cell dry weight) values. BRI 3010 and BRI 6011 accumulated benzoic acid against a concentration gradient by a factor of 8 and 10, respectively. A wide range of structural analogs, at 50-fold excess concentrations, inhibited benzoic acid uptake by BRI 3010 and BRI 6011, whereas with B13, only 3-chlorobenzoic acid was an effective inhibitor. For BRI 3010 and BRI 6011, the inhibition by the structural analogs was not of a competitive nature. Uptake of benzoic acid by BRI 3010 and BRI 6011 was inhibited by KCN, by the protonophore 3,5,3`, 4`-tetrachlorosalicylanilide (TCS), and, for BRI 6011, by anaerobiosis unless nitrate was present, thus indicating that energy was required for the uptake process. Uptake of 2,4-DCBA by BRI 6011 was constitutive and saturation uptake kinetics were not observed. Uptake of 2,4-DCBA by BRI 6011 was inhibited by KCN, TCS, and anaerobiosis even if nitrate was present, but the compound was not accumulated intracellularly against a concentration gradient. Uptake of 2,4-DCBA by BRI 6011 appears to occur by passive diffusion into the cell down its concentration gradient, which is maintained by the intracellular metabolism of the compound. This process could play an important role in the degradation of xenobiotic compounds by microorganisms.

  4. Uptake of aristolochic acid I into Caco-2 cells by monocarboxylic acid transporters.

    PubMed

    Kimura, Osamu; Haraguchi, Koichi; Ohta, Chiho; Koga, Nobuyuki; Kato, Yoshihisa; Endo, Tetsuya

    2014-01-01

    The uptake mechanism of aristolochic acid I (AAI) was investigated using Caco-2 cells cultured on dishes and permeable membranes. The uptake of AAI from the apical membrane of Caco-2 cells cultured on a dish was rapid, and a decrease in the pH of the incubation medium significantly increased uptake. Incubation at low temperature (4°C) and treatment with sodium azide (a metabolic inhibitor) or carbonylcyanide p-trifluoromethoxyphenylhydrazone (a protonophore) significantly inhibited the AAI uptake. Coincubation with L-lactic acid or benzoic acid, typical substrates for the proton-linked monocarboxylic acid transporters (MCTs), significantly decreased the AAI uptake, as did coincubation with α-cyano-4-hydroxycinnamate (an inhibitor of MCTs). Dixon plotting revealed the competitive inhibition of benzoic acid on the AAI uptake. To confirm the AAI uptake via MCTs, the apical-to-basolateral transport of AAI was investigated using the Caco-2 cells cultured on the permeable membranes. The transport of AAI at pH 6.0 was markedly higher than that at pH 7.4, and was significantly decreased by coincubation with benzoic acid. These results suggest that the uptake of AAI from the apical membrane of Caco-2 cells is mediated mainly by MCTs along with benzoic acid. PMID:25177030

  5. Uptake of gaseous nitrous acid (HONO) by several plant species

    NASA Astrophysics Data System (ADS)

    Schimang, Ralf; Folkers, Achim; Kleffmann, Jörg; Kleist, Einhard; Miebach, Marco; Wildt, Jürgen

    Uptake of gaseous nitrous acid (HONO) by sunflower ( Heliantus annuus L. var. gigantheus), tobacco ( Nicotiana tabacum L. var. Bel W3), castor ( Rhicinus communis L. var. Carmencita), and birch ( Betula pendula L.) was studied under controlled conditions in a continuously stirred tank reactor. Exposing plants to HONO at concentrations between 60 ppt and 10 ppb led to significant uptake by the plants. The uptake was proportional to HONO concentrations and linearly related to stomatal conductivity. HONO losses at the cuticle were of minor importance. Our data imply a quick metabolism of HONO and it is concluded that the uptake of HONO by plants is only limited by diffusion of HONO through the plants stomata. Comparing results from measurements with and without plants in the chamber it is furthermore concluded that a compensation point for HONO uptake is below 20 ppt if it exists at all. Heterogeneous formation of HONO by reactions of NO 2 on the plant surfaces was either not effective or compensated by the stomatal uptake of HONO. The data of the present study imply that plant surfaces represent a sink for HONO. Therefore, it was concluded that processes on plant surfaces cannot explain HONO formation on ground surfaces as observed in field studies.

  6. Free ferulic acid uptake in lactating cows.

    PubMed

    Soberon, M A; Cherney, J H; Liu, R H; Ross, D A; Cherney, D J R

    2012-11-01

    Ferulic acid (FRA), a phenolic compound with antioxidant and anticancer activities, naturally occurs in plants as a lignin precursor. Many veins of research have been devoted to releasing FRA from the lignin complex to improve digestibility of ruminant feeds. Thus, the objective of this research was to investigate the transfer of a given dosage of the free form of FRA into the milk of dairy cattle. Six mid- to late-lactation Holstein cows at the Cornell Research Farm (Harford, NY) were given 14-d adaptation to diet and stall position. Ad libitum access to a total mixed ration based on haylage and maize silage (31.1% neutral detergent fiber containing 5.52 mg of FRA/g) was provided during the study. A crossover design was implemented so that each cow alternated weekly between FRA-dosed and control. On d 1, jugular cannulas and urine catheters were placed in all cows. On d 2, FRA-dosed cows received a single dosage of 150 g of pure FRA powder at 0830 h via their fistula (n=4) or a balling gun for nonfistulated cows (n=2). Plasma, urine, feces, feed, orts, milk, and rumen fluid were sampled intensively for the next 36 h and analyzed for FRA concentration. On d 8, the cows crossed over and the experiment was repeated. When compared with the control, FRA administration did not have an effect on dry matter intake, milk yield, milk fat yield, milk protein yield, somatic cell count, or neutral detergent fiber content of orts and feces. The concentration of FRA in the feces did not change as a result of FRA dosage. As expected, FRA concentration increased dramatically upon FRA dosage and decreased over time until returning to basal levels in rumen fluid (4 h after dosage), plasma (5.5 h after dosage), urine (10 h after dosage), and milk (14 h after dosage). Baseline values for FRA in urine and rumen fluid were variable among cows and had an effect on FRA concentration in FRA-dosed cows. From this study, it is observed that orally ingested FRA can be transported into the

  7. Uptake of metal ions on humic acids

    SciTech Connect

    Pehlivan, E.; Arslan, G.

    2006-09-15

    The kinetics, the sorption capacities, pH and temperature dependence of sorption of humic acids (HAs) of Turkish brown coals with respect to Zn(II), Cu(II), Ni(II), Co(II) and Pb(II) ions were investigated, and the roles of the carboxylic and phenolic groups in the adsorption of metals ion on HAs were searched in this work. These metal ions are able to form complex compounds with carboxylic and phenolic groups of HAs. Adsorption equilibrium was achieved in between 50 and 60 min for all studied cations. HAs extracted from different brown coals have been characterized by chemical and physical methods. The chemical properties of HAs showed differences depending on the source from which they were obtained. The sorption of metals on the surface of HAs depends strongly on the pH, and sorption decreases with decreasing pH. Maximum removal of metal ions was demonstrated at pH values of 4.1-5.0. The Langmuir adsorption isotherm was used to describe observed sorption phenomena. The {Delta}G{sup 0} became negative as the temperature increased, and so the equilibrium constant decreased slightly. The investigation proved that the HAs are suitable materials for the studied heavy metal ion removal from aqueous solution and could be considered as potential material for purification of effluent polluted with toxic metal ions.

  8. Carrier-mediated system for pefloxacin uptake in human monocytes.

    PubMed

    Mémin, E; Panteix, G; Revol, A

    1997-08-01

    Protein transporters present in cellular membranes can influence the intracellular concentration of a variety of drugs. Pefloxacin is a fluoroquinolone which is commonly used in systemic infections. Its transport mechanisms have never been described. In the present study, we demonstrated that pefloxacin uptake is carrier-mediated. Pefloxacin crosses the membrane in zwitterionic form. The transport seems to differ from that of other fluoroquinolones which use amino acid or organic anion transporters. Pefloxacin uptake is not influenced by the presence of hexose in the incubation medium. It does not use a nucleoside transport system to penetrate the cells but adenosine increases the uptake. The carrier is inhibited by verapamil at 60 min and is activated by a Ca2+-dependent system. PMID:9301993

  9. gamma-Aminobutyric acid uptake inhibition and anticonvulsant activity of nipecotic acid esters.

    PubMed

    Crider, A M; Wood, J D; Tschappat, K D; Hinko, C N; Seibert, K

    1984-11-01

    n-Alkyl esters of nipecotic acid were prepared by Fischer esterification, and the esters were evaluated against bicuculline-induced seizures in mice. Evaluation of the alkyl esters for inhibition of gamma-aminobutyric acid uptake into mouse whole brain mini-slices revealed that the order of potency was proportional to chain length. The octyl ester inhibited gamma-aminobutyric acid and beta-alanine uptakes by apparently nonspecific mechanisms. A variety of phenyl esters of nipecotic acid were also synthesized utilizing either dicyclohexylcarbodiimide or 1,1'-carbonyldiimidazole as the condensing agent. Most of the phenyl esters were potent inhibitors of gamma-aminobutyric acid uptake. The uptake inhibition appeared to involve specific and nonspecific (detergent-like) mechanisms. The m-nitrophenyl and p-nitrophenyl esters were particularly potent against bicuculline-induced seizures in mice. PMID:6520765

  10. Tracking the morphology of fulvic acids during water uptake

    NASA Astrophysics Data System (ADS)

    Zelenay, Veronika; Krepelova, Adela; Rudich, Yinon; Huthwelker, Thomas; Ammann, Markus

    2010-05-01

    a microdispenser or as aerosol particles on the sample holder of the microreactor. The resulting dry droplet residues reached a size of about 20 -30 μm or around 0.5 μm, respectively. Using this setup we could obtain unique images showing the microstructure of the fulvic acid before and during exposure to water vapor in situ. Significant changes in morphology occurred upon water uptake, and the system consisted of a solution with embedded micron-sized colloidal particles. This further allows linking the chemical functional groups with their degree of hydration. Additional measurements were performed with two fractionated fulvic acids of low (0.5-1 kDa) and high (10-30 kDa) molecular weight. Both fractions were first analyzed for their functional and their hygroscopic properties. Although the functional group analysis shows differences, the morphology of these two fractions was found to be similar. Under dry conditions, the residues were more homogeneous over the droplet dimensions than for the unfractionated samples. Under wet conditions, the two fractions differed in the amount of water taken up but were similar in the degree to which more phenolic subunits were apparent.

  11. Inhibition of sugar uptake by ascorbic acid in Escherichia coli.

    PubMed

    Loewen, P C; Richter, H E

    1983-10-15

    The uptake of glucose by the glucose phosphotransferase system in Escherichia coli was inhibited greater than 90% by ascorbate. The uptake of the nonmetabolizable analog of glucose, methyl-alpha-glucoside, was also inhibited to the same extent, confirming that it was the transport process that was sensitive to ascorbate. Similarly, it was the transport function of mannose phosphotransferase for which mannose and nonmetabolizable 2-deoxyglucose were substrates that was partially inhibited by ascorbate. Other phosphotransferase systems, including those for the uptake of sorbitol, fructose and N-acetylglucosamine, but not mannitol, were also inhibited to varying degrees by ascorbate. The inhibitory effect on the phosphotransferase systems was reversible, required the active oxidation of ascorbate, was sensitive to the presence of free-radical scavengers, and was insensitive to uncouplers. Because ascorbate was not taken up by E. coli, it was concluded that the active inhibitory species was the ascorbate free radical and that it was interacting reversibly with a membrane component, possibly the different enzyme IIB components of the phosphotransferase systems. Ascorbate also inhibited other transport systems causing a slight reduction in the passive diffusion of glycerol, a 50% inhibition of the shock-sensitive uptake of maltose, and a complete inhibition of the proton-symport uptake of lactose. Radical scavengers had little or no effect on the inhibition of these systems. PMID:6357094

  12. Methanol Uptake By Low Temperature Aqueous Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Essin, Andrew M.; Golden, David M.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    To evaluate the role of upper tropospheric and lower stratospheric aerosols in the global budget of methanol, the solubility and reactivity of CH3OH in aqueous sulfuric acid solutions are under investigation. Using standard uptake techniques in a Knudsen cell reactor, we have measured the effective Henry's law coefficient, H(*), for methanol dissolution into 45 to 70 percent by weight H2SO4. We find that methanol solubility ranges from 10(exp 5) to 10(exp 8) M/atm and increases with decreasing temperature and with increasing sulfuric acid content. These solubility measurements include uptake due to physical solvation and all rapid equilibria which are established in solution. Our data indicate that simple uptake by aqueous sulfuric acid particles will not be a significant sink for methanol in the UT/LS. These results differ from those recently reported in the literature, and an explanation of this disparity will be presented. In addition to solvation, reaction between primary alcohols and sulfuric acid does occur, leading to the production of alkyl sulfates. Literature values for the rate of this reaction suggest that formation of CH3OSO3H may proceed in the atmosphere but is not significant under our experimental conditions. Results obtained using a complementary equilibrium measurement technique confirm this directly. In addition, the extent of methanol sequestration via formation of mono- and dimethylsulfate will be evaluated under several atmospheric conditions.

  13. Methanol Uptake by Low Temperature Aqueous Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Iraci, L. T.; Essin, A. M.; Golden, D. M.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    The global methanol budget is currently unbalanced, with source terms significantly larger than the sinks terms. To evaluate possible losses of gaseous methanol to sulfate aerosols, the solubility and reactivity of methanol in aqueous sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosols is under investigation. Methanol will partition into sulfate aerosols according to its Henry's law solubility. Using standard uptake techniques in a Knudsen cell reactor, we have measured the effective Henry's law coefficient, H*, for cold (196 - 220 K) solutions ranging between 45 and 70 wt % H2SO4. We have found that methanol solubility ranges from approx. 10(exp 5) - 10(exp 7) M/atm for UT/LS conditions. Solubility increases with decreasing temperature and with increasing sulfuric acid content. Although methanol is slightly more soluble than are acetone and formaldehyde, current data indicate that uptake by clean aqueous sulfuric acid particles will not be a significant sink for methanol in the UT/LS. These solubility measurements include uptake due to physical solvation and any rapid equilibria which are established in solution. Reaction between primary alcohols and sulfuric acid does occur, leading to the production of alkyl sulfates. Literature values for the rate of this reaction suggest that formation of CH3OSO3H is not significant over our experimental time scale for solutions below 80 wt % H2SO4. To confirm this directly, results obtained using a complementary equilibrium measurement technique will also be presented.

  14. Nitric acid uptake by sulfuric acid solutions under stratospheric conditions - Determination of Henry's Law solubility

    NASA Technical Reports Server (NTRS)

    Reihs, Christa M.; Golden, David M.; Tolbert, Margaret A.

    1990-01-01

    The uptake of nitric acid by sulfuric acid solutions representative of stratospheric particulate at low temperatures was measured to determine the solubility of nitric acid in sulfuric acid solutions as a function of H2SO4 concentration and solution temperature. Solubilities are reported for sulfuric acid solutions ranging from 58 to 87 wt pct H2SO4 over a temperature range from 188 to 240 K, showing that, in general, the solubility of nitric acid increases with decreasing sulfuric acid concentration and with decreasing temperature. The measured solubilities indicate that nitric acid in the global stratosphere will be found predominantly in the gas phase.

  15. Enhancement effect of poly(amino acid)s on insulin uptake in alveolar epithelial cells.

    PubMed

    Oda, Keisuke; Yumoto, Ryoko; Nagai, Junya; Katayama, Hirokazu; Takano, Mikihisa

    2012-01-01

    In this study, we elucidated the effect of poly(amino acid)s such as poly-L-ornithine (PLO) on FITC-insulin uptake in cultured alveolar type II epithelial cells, RLE-6TN. FITC-insulin uptake by RLE-6TN cells as well as its cell surface binding was markedly increased by PLO without cytotoxicity. The uptake of FITC-insulin in the presence of PLO was shown to be mediated by endocytosis, but in contrast to the uptake in the absence of PLO, the contribution of macropinocytosis emerged. Colocalization of FITC-insulin and LysoTracker Red was observed by confocal laser scanning microscopy both in the absence and presence of PLO, indicating that FITC-insulin was partly targeted to lysosomes in the cells and degraded. The half-life of the intracellular degradation of FITC-insulin was, however, prolonged by the presence of PLO. PLO also stimulated the uptake of other FITC-labeled compounds. Among them, the enhancement effects of PLO on FITC-albumin and FITC-insulin uptake were prominent. The effect of PLO on insulin absorption was also examined in in-vivo pulmonary administration in rats, and co-administration of PLO enhanced the hypoglycemic action of insulin. These findings suggest that co-administration of poly(amino acid)s such as PLO is a useful strategy for enhancing insulin uptake by alveolar epithelial cells and subsequent absorption from the lung. PMID:22510869

  16. Opposite regulation of CD36 ubiquitination by fatty acids and insulin: effects on fatty acid uptake.

    PubMed

    Smith, Jill; Su, Xiong; El-Maghrabi, Raafat; Stahl, Philip D; Abumrad, Nada A

    2008-05-16

    FAT/CD36 is a membrane scavenger receptor that facilitates long chain fatty acid uptake by muscle. Acute increases in membrane CD36 and fatty acid uptake have been reported in response to insulin and contraction. In this study we have explored protein ubiquitination as one potential mechanism for the regulation of CD36 level. CD36 expressed in Chinese hamster ovary (CHO) or HEK 293 cells was found to be polyubiquitinated via a process involving both lysines 48 and 63 of ubiquitin. Using CHO cells expressing the insulin receptor (CHO/hIR) and CD36, it is shown that addition of insulin (100 nm, 10 and 30 min) significantly reduced CD36 ubiquitination. In contrast, ubiquitination was strongly enhanced by fatty acids (200 microm palmitate or oleate, 2 h). Similarly, endogenous CD36 in C2C12 myotubes was ubiquitinated, and this was enhanced by oleic acid treatment, which also reduced total CD36 protein in cell lysates. Insulin reduced CD36 ubiquitination, increased CD36 protein, and inhibited the opposite effects of fatty acids on both parameters. These changes were paralleled by changes in fatty acid uptake, which could be blocked by the CD36 inhibitor sulfosuccinimidyl oleate. Mutation of the two lysine residues in the carboxyl-terminal tail of CD36 markedly attenuated ubiquitination of the protein expressed in CHO cells and was associated with increased CD36 level and enhanced oleate uptake and incorporation into triglycerides. In conclusion, fatty acids and insulin induce opposite alterations in CD36 ubiquitination, modulating CD36 level and fatty acid uptake. Altered CD36 turnover may contribute to abnormal fatty acid uptake in the insulin-resistant muscle. PMID:18353783

  17. Uptake and metabolic effects of salicylic acid on the pulvinar motor cells of Mimosa pudica L.

    PubMed

    Dédaldéchamp, Fabienne; Saeedi, Saed; Fleurat-Lessard, Pierrette; Roblin, Gabriel

    2014-01-01

    In this paper, the salicylic acid (o-hydroxy benzoic acid) (SA) uptake by the pulvinar tissues of Mimosa pudica L. pulvini was shown to be strongly pH-dependent, increasing with acidity of the assay medium. This uptake was performed according to a unique affinity system (K(m) = 5.9 mM, V(m) = 526 pmol mgDW(-1)) in the concentration range of 0.1-5 mM. The uptake rate increased with increasing temperature (5-35 °C) and was inhibited following treatment with sodium azide (NaN3) and carbonyl cyanide m-chlorophenylhydrazone (CCCP), suggesting the involvement of an active component. Treatment with p-chloromercuribenzenesulfonic acid (PCMBS) did not modify the uptake, indicating that external thiol groups were not necessary. KCl, which induced membrane depolarization had no significant effect, and fusicoccin (FC), which hyperpolarized cell membrane, stimulated the uptake, suggesting that the pH component of the proton motive force was likely a driving force. These data suggest that the SA uptake by the pulvinar tissues may be driven by two components: an ion-trap mechanism playing a pivotal role and a putative carrier-mediated mechanism. Unlike other benzoic acid derivatives acting as classical respiration inhibitors (NaN3 and KCN), SA modified the pulvinar cell metabolism by increasing the respiration rate similar to CCCP and 2,4-dinitrophenol (DNP). Furthermore, SA inhibited the osmoregulated seismonastic reaction in a pH dependent manner and induced characteristic damage to the ultrastructural features of the pulvinar motor cells, particularly at the mitochondrial level. PMID:24292275

  18. Modelling water uptake efficiency of root systems

    NASA Astrophysics Data System (ADS)

    Leitner, Daniel; Tron, Stefania; Schröder, Natalie; Bodner, Gernot; Javaux, Mathieu; Vanderborght, Jan; Vereecken, Harry; Schnepf, Andrea

    2016-04-01

    Water uptake is crucial for plant productivity. Trait based breeding for more water efficient crops will enable a sustainable agricultural management under specific pedoclimatic conditions, and can increase drought resistance of plants. Mathematical modelling can be used to find suitable root system traits for better water uptake efficiency defined as amount of water taken up per unit of root biomass. This approach requires large simulation times and large number of simulation runs, since we test different root systems under different pedoclimatic conditions. In this work, we model water movement by the 1-dimensional Richards equation with the soil hydraulic properties described according to the van Genuchten model. Climatic conditions serve as the upper boundary condition. The root system grows during the simulation period and water uptake is calculated via a sink term (after Tron et al. 2015). The goal of this work is to compare different free software tools based on different numerical schemes to solve the model. We compare implementations using DUMUX (based on finite volumes), Hydrus 1D (based on finite elements), and a Matlab implementation of Van Dam, J. C., & Feddes 2000 (based on finite differences). We analyse the methods for accuracy, speed and flexibility. Using this model case study, we can clearly show the impact of various root system traits on water uptake efficiency. Furthermore, we can quantify frequent simplifications that are introduced in the modelling step like considering a static root system instead of a growing one, or considering a sink term based on root density instead of considering the full root hydraulic model (Javaux et al. 2008). References Tron, S., Bodner, G., Laio, F., Ridolfi, L., & Leitner, D. (2015). Can diversity in root architecture explain plant water use efficiency? A modeling study. Ecological modelling, 312, 200-210. Van Dam, J. C., & Feddes, R. A. (2000). Numerical simulation of infiltration, evaporation and shallow

  19. Relating physical state and reactivity: humidity dependent ozone uptake on tannic and shikimic acid

    NASA Astrophysics Data System (ADS)

    Steimer, S.; Huisman, A.; Krieger, U.; Lampimäki, M.; Marcolli, C.; Peter, T.; Ammann, M.

    2012-04-01

    Atmospheric aerosols are an important focus of environmental research due to their effect on climate and human health. Recent findings show that organic aerosol particles are capable of forming amorphous solids and semi-solids under atmospheric conditions [1]. Such particles should be highly viscous, leading to low diffusivity within the bulk. This would then slow down eventual chemical reactions in the bulk, thereby increasing the lifetime of the organic compounds involved. First indications of such behavior were recently shown for the reaction of thin protein films with ozone [2]. To investigate the influence of the physical state on the reactivity of atmospherically relevant compounds, the uptake of ozone on two different organics was measured using a coated wall flow tube system. The investigated organic compounds are tannic acid, which is a proxy for atmospheric polyphenolic materials, and shikimic acid, a constituent of biomass burning aerosols. The viscosity of the organic film was adjusted by varying the humidity of the system, assuming a correlation between the two parameters due to water acting as a plasticizer. The investigated humidity range was 0% - 95% RH for tannic and 0% - 92% RH for shikimic acid. It was found that both of the compounds show a long term uptake of ozone which lasts for more than 20 h. The uptake coefficient is clearly humidity dependent and increases by close to two orders of magnitude between driest and wettest conditions. At a given humidity, shikimic acid is the more reactive compound. The measured humidity dependence supports the hypothesis that the uptake coefficient is a strong function of the diffusion coefficient of ozone in the organic film. 1. Virtanen, A., et al., An amorphous solid state of biogenic secondary organic aerosol particles. Nature, 2010. 467(7317): p. 824-827. 2. Shiraiwa, M., et al., Gas uptake and chemical aging of semisolid organic aerosol particles. Proceedings of the National Academy of Sciences of the

  20. Real time non invasive imaging of fatty acid uptake in vivo

    PubMed Central

    Henkin, Amy H.; Cohen, Allison S.; Dubikovskaya, Elena A.; Park, Hyo Min; Nikitin, Gennady F.; Auzias, Mathieu G.; Kazantzis, Melissa; Bertozzi, Carolyn R.; Stahl, Andreas

    2012-01-01

    Detection and quantification of fatty acid fluxes in animal model systems following physiological, pathological, or pharmacological challenges is key to our understanding of complex metabolic networks as these macronutrients also activate transcription factors and modulate signaling cascades including insulin-sensitivity. To enable non-invasive, real-time, spatiotemporal quantitative imaging of fatty acid fluxes in animals, we created a bioactivatable molecular imaging probe based on long-chain fatty acids conjugated to a reporter molecule (luciferin). We show that this probe faithfully recapitulates cellular fatty acid uptake and can be used in animal systems as a valuable tool to localize and quantitate in real-time lipid fluxes such as intestinal fatty acid absorption and brown adipose tissue activation. This imaging approach should further our understanding of basic metabolic processes and pathological alterations in multiple disease models. PMID:22928772

  1. Uptake of auxins into membrane vesicles isolated from pea stems: an in vitro auxin transport system

    SciTech Connect

    Slone, J.H.

    1985-01-01

    The objective of this research was to test the applicability of the chemiosmotic theory of auxin transport to a subcellular system. Membrane vesicles were isolated from the basal portion of the third internode of etiolated pea plants (Pisum sativum L. var. Alaska) by differential centrifugation. Uptake of auxin was determined by adding /sup 14/C-labeled indoleacetic acid (IAA) to vesicles. Nigericin, a monovalent cation ionophore, and the electrogenic protonophore, carbonyl-cyanide m-chlorophenylhydrazone (CCCP), at micromolar concentrations abolished saturable uptake. Bursting vesicles by sonication, osmotic shock and freeze/thawing also eliminated saturable uptake. As the temperature increased from 0 to 30/sup 0/C, saturable uptake decreased markedly. Nonsaturable auxin uptake was less affected by these treatments. The pH gradient-dependent uptake of auxin appeared to be a transmembrane uptake of auxin into the vesicles rather than surface binding. Unlabeled IAA, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-naphthaleneacetic acid (NAA) at low concentrations reduced the saturable accumulation of (/sup 14/C)IAA in vesicles, while phenylacetic acid, benzoic acid, and 1-NAA were effective only at high concentrations. Kinetic analysis revealed two types of sites: a high affinity site with an uptake capacity of 25 to 40 pmoles/g tissue, and a low affinity site with an uptake capacity of 260 to 600 pmole/g tissue, fresh wt. In conclusion, several principal elements of an auxin transport system, as specific by the chemiosmotic theory of polar auxin transport, were present in membrane vesicles isolated from relatively mature pea stem tissue. However, one important aspect of the theory was not demonstrated in this in vitro system - a TIBA/NPA-sensitive auxin efflux. The kinetics and specificity of auxin uptake strongly suggested that this system was physiologically significant.

  2. Uptake of Amino Acids and Other Organic Compounds by Lemna paucicostata Hegelm. 6746

    PubMed Central

    Datko, Anne H.; Mudd, S. Harvey

    1985-01-01

    A survey of the capacity of Lemna paucicostata to take up organic compounds such as might be present in the natural environment of this plant has identified eight discrete transport systems. Reciprocal inhibition studies defined the preferred substrates for these systems as follows: (a) neutral l-α-amino acids, (b) basic amino acids, (c) purine bases, (d) choline, (e) ethanolamine, (f) tyramine, (g) urea, and (h) aldohexoses. Each of these systems takes up its preferred substrates at high rates. At low concentrations, each Lemna frond during each minute takes up amounts which would be found in volumes ranging from 0.4 (tyramine) to 3.9 (urea) times its own volume. The two systems for amino acid transport both showed kinetics of the biphasic type, so that uptake by each can be described as the composite result of two Michaelis-Menten processes. The neutral amino acid system neither transports basic amino acids nor is inhibited by these compounds. The basic amino acid system does not transport neutral amino acids but is strongly inhibited by some, but not all, of these compounds. It is argued that the maintenance of these active, specific, and discrete systems in Lemna suggests they play important roles permitting this plant to utilize organic compounds occurring naturally in its environment. PMID:16664132

  3. Stromal uptake and transmission of acid is a pathway for venting cancer cell-generated acid.

    PubMed

    Hulikova, Alzbeta; Black, Nicholas; Hsia, Lin-Ting; Wilding, Jennifer; Bodmer, Walter F; Swietach, Pawel

    2016-09-01

    Proliferation and invasion of cancer cells require favorable pH, yet potentially toxic quantities of acid are produced metabolically. Membrane-bound transporters extrude acid from cancer cells, but little is known about the mechanisms that handle acid once it is released into the poorly perfused extracellular space. Here, we studied acid handling by myofibroblasts (colon cancer-derived Hs675.T, intestinal InMyoFib, embryonic colon-derived CCD-112-CoN), skin fibroblasts (NHDF-Ad), and colorectal cancer (CRC) cells (HCT116, HT29) grown in monoculture or coculture. Expression of the acid-loading transporter anion exchanger 2 (AE2) (SLC4A2 product) was detected in myofibroblasts and fibroblasts, but not in CRC cells. Compared with CRC cells, Hs675.T and InMyoFib myofibroblasts had very high capacity to absorb extracellular acid. Acid uptake into CCD-112-CoN and NHDF-Ad cells was slower and comparable to levels in CRC cells, but increased alongside SLC4A2 expression under stimulation with transforming growth factor β1 (TGFβ1), a cytokine involved in cancer-stroma interplay. Myofibroblasts and fibroblasts are connected by gap junctions formed by proteins such as connexin-43, which allows the absorbed acid load to be transmitted across the stromal syncytium. To match the stimulatory effect on acid uptake, cell-to-cell coupling in NHDF-Ad and CCD-112-CoN cells was strengthened with TGFβ1. In contrast, acid transmission was absent between CRC cells, even after treatment with TGFβ1. Thus, stromal cells have the necessary molecular apparatus for assembling an acid-venting route that can improve the flow of metabolic acid through tumors. Importantly, the activities of stromal AE2 and connexin-43 do not place an energetic burden on cancer cells, allowing resources to be diverted for other activities. PMID:27543333

  4. Arachidonic acid induces a prolonged inhibition of glutamate uptake into glial cells.

    PubMed

    Barbour, B; Szatkowski, M; Ingledew, N; Attwell, D

    Activation of NMDA (N-methyl-D-aspartate) receptors by neurotransmitter glutamate stimulates phospholipase A2 to release arachidonic acid. This second messenger facilitates long-term potentiation of glutamatergic synapses in the hippocampus, possibly by blocking glutamate uptake. We have studied the effect of arachidonic acid on glutamate uptake into glial cells using the whole-cell patch-clamp technique to monitor the uptake electrically. Micromolar levels of arachidonic acid inhibit glutamate uptake, mainly by reducing the maximum uptake rate with only small effects on the affinity for external glutamate and sodium. On removal of arachidonic acid a rapid (5 minutes) phase of partial recovery is followed by a maintained suppression of uptake lasting at least 20 minutes. Surprisingly, the action of arachidonic acid is unaffected by cyclo-oxygenase or lipoxygenase inhibitors suggesting that it inhibits uptake directly, possibly by increasing membrane fluidity. As blockade of phospholipase A2 prevents the induction of long-term potentiation (LTP), inhibition of glutamate uptake by arachidonic acid may contribute to the increase of synaptic gain that occurs in LTP. During anoxia, release of arachidonic acid could severely compromise glutamate uptake and thus contribute to neuronal death. PMID:2512508

  5. γ-Aminobutyric Acid Transporter 2 Mediates the Hepatic Uptake of Guanidinoacetate, the Creatine Biosynthetic Precursor, in Rats

    PubMed Central

    Tachikawa, Masanori; Ikeda, Saori; Fujinawa, Jun; Hirose, Shirou; Akanuma, Shin-ichi; Hosoya, Ken-ichi

    2012-01-01

    Guanidinoacetic acid (GAA) is the biosynthetic precursor of creatine which is involved in storage and transmission of phosphate-bound energy. Hepatocytes readily convert GAA to creatine, raising the possibility that the active uptake of GAA by hepatocytes is a regulatory factor. The purpose of this study is to investigate and identify the transporter responsible for GAA uptake by hepatocytes. The characteristics of [14C]GAA uptake by hepatocytes were elucidated using the in vivo liver uptake method, freshly isolated rat hepatocytes, an expression system of Xenopus laevis oocytes, gene knockdown, and an immunohistochemical technique. In vivo injection of [14C]GAA into the rat femoral vein and portal vein results in the rapid uptake of [14C]GAA by the liver. The uptake was markedly inhibited by γ-aminobutyric acid (GABA) and nipecotinic acid, an inhibitor of GABA transporters (GATs). The characteristics of Na+- and Cl−-dependent [14C]GAA uptake by freshly isolated rat hepatocytes were consistent with those of GAT2. The Km value of the GAA uptake (134 µM) was close to that of GAT2-mediated GAA transport (78.9 µM). GABA caused a marked inhibition with an IC50 value of 8.81 µM. The [14C]GAA uptake exhibited a significant reduction corresponding to the reduction in GAT2 protein expression. GAT2 was localized on the sinusoidal membrane of the hepatocytes predominantly in the periportal region. This distribution pattern was consistent with that of the creatine biosynthetic enzyme, S-adenosylmethionine∶guanidinoacetate N-methyltransferase. GAT2 makes a major contribution to the sinusoidal GAA uptake by periportal hepatocytes, thus regulating creatine biosynthesis in the liver. PMID:22384273

  6. γ-Aminobutyric acid transporter 2 mediates the hepatic uptake of guanidinoacetate, the creatine biosynthetic precursor, in rats.

    PubMed

    Tachikawa, Masanori; Ikeda, Saori; Fujinawa, Jun; Hirose, Shirou; Akanuma, Shin-ichi; Hosoya, Ken-ichi

    2012-01-01

    Guanidinoacetic acid (GAA) is the biosynthetic precursor of creatine which is involved in storage and transmission of phosphate-bound energy. Hepatocytes readily convert GAA to creatine, raising the possibility that the active uptake of GAA by hepatocytes is a regulatory factor. The purpose of this study is to investigate and identify the transporter responsible for GAA uptake by hepatocytes. The characteristics of [(14)C]GAA uptake by hepatocytes were elucidated using the in vivo liver uptake method, freshly isolated rat hepatocytes, an expression system of Xenopus laevis oocytes, gene knockdown, and an immunohistochemical technique. In vivo injection of [(14)C]GAA into the rat femoral vein and portal vein results in the rapid uptake of [(14)C]GAA by the liver. The uptake was markedly inhibited by γ-aminobutyric acid (GABA) and nipecotinic acid, an inhibitor of GABA transporters (GATs). The characteristics of Na(+)- and Cl(-)-dependent [(14)C]GAA uptake by freshly isolated rat hepatocytes were consistent with those of GAT2. The Km value of the GAA uptake (134 µM) was close to that of GAT2-mediated GAA transport (78.9 µM). GABA caused a marked inhibition with an IC(50) value of 8.81 µM. The [(14)C]GAA uptake exhibited a significant reduction corresponding to the reduction in GAT2 protein expression. GAT2 was localized on the sinusoidal membrane of the hepatocytes predominantly in the periportal region. This distribution pattern was consistent with that of the creatine biosynthetic enzyme, S-adenosylmethionine:guanidinoacetate N-methyltransferase. GAT2 makes a major contribution to the sinusoidal GAA uptake by periportal hepatocytes, thus regulating creatine biosynthesis in the liver. PMID:22384273

  7. Dependence of intestinal amino acid uptake on dietary protein or amino acid levels

    SciTech Connect

    Karasov, W.H.; Solberg, D.H.; Diamond, J.M.

    1987-05-01

    To understand how intestinal amino acid (AA) transport is regulated by dietary substrate levels, the authors measured uptake of seven radioactively-labelled AAs and glucose across the jejunal brush-border membrane of mice kept on one of three isocaloric rations differing in nitrogen content. In the high-protein ration, uptake increased by 77-81% for the nonessential, less toxic AAs, proline, and aspartate but only by 32-61% for the more toxic essential AAs tested. In the nitrogen-deficient ration, uptake decreased for the nonessential aspartate and proline but stayed constant or increased for essential AAs and for the nonessential alanine. These patterns imply independent regulation of the intestine's various AA transporters. With decreasing dietary AA (or protein), the imino acid and acidic AA private transporters are repressed, while activities of the basic AA transporter and the neutral AA public transporter decrease to an asymptote or else go through a minimum. These regulatory patterns can be understood as a compromise among conflicting constraints imposed by protein's multiple roles as a source of calories, nitrogen, and essential AAs and by the toxicity of essential AAs at high concentrations.

  8. Effects of heat and other agents on amino acid uptake in Escherichia coli.

    PubMed

    Wainberg, R H; Watkins, D K; Stebler, B A; Cramp, W A; Yatvin, M B

    1990-01-01

    In Escherichia coli K1060 grown at 37 degrees C we observed that the uptake of both L-[3H]leucine and L-[35S]methionine was inhibited by exposure of the cells to 48 degrees C. The calcium channel blockers diltiazem and verapamil, and the anti-arrhythmic agent quinidine, inhibited the uptake of L-[3H]leucine at both 37 degrees C and 48 degrees C. Verapamil also inhibited the uptake of L-[35S]methionine at 37 degrees C, but at 48 degrees C protected against some of the heat-induced decrease in the uptake of this amino acid. The local anaesthetic procaine markedly inhibited the uptake of both labelled amino acids at temperatures between 37 degrees C and 48 degrees C. Amino acid uptake and cell killing were not correlated. PMID:2198313

  9. The effect of fatty acid surfactants on the uptake of nitric acid to deliquesced NaCl aerosol

    NASA Astrophysics Data System (ADS)

    Stemmler, K.; Vlasenko, A.; Guimbaud, C.; Ammann, M.

    2008-01-01

    Surface active organic compounds have been observed in marine boundary layer aerosol. Here, we investigate the effect such surfactants have on the uptake of nitric acid (HNO3), an important removal reaction of nitrogen oxides in the marine boundary layer. The uptake of gaseous HNO3 on deliquesced NaCl aerosol was measured in a flow reactor using HNO3 labelled with the short-lived radioactive isotope 13N. The uptake coefficient γ on pure deliquesced NaCl aerosol was γ=0.5±0.2 at 60% relative humidity and 30 ppb HNO3(g). The uptake coefficient was reduced by a factor of 5-50 when the aerosol was coated with saturated linear fatty acids with carbon chain lengths of 18 and 15 atoms in monolayer quantities. In contrast, neither shorter saturated linear fatty acids with 12 and 9 carbon atoms, nor coatings with the unsaturated oleic acid (C18, cis-double bond) had a detectable effect on the rate of HNO3 uptake. It is concluded that it is the structure of the monolayers formed, which determines their resistance towards HNO3 uptake. Fatty acids (C18 and C15), which form a highly ordered film in the so-called liquid condensed state, represent a significant barrier towards HNO3 uptake, while monolayers of shorter-chain fatty acids (C9, C12) and of the unsaturated oleic acid form a less ordered film in the liquid expanded state and do not hinder the uptake. Similarly, high contents of humic acids in the aerosol, a structurally inhomogeneous, quite water soluble mixture of oxidised high molecular weight organic compounds did not affect HNO3 uptake. As surfactant films on naturally occurring aerosol are expected to be less structured due to their chemical inhomogeneity, it is likely that their inhibitory effect on HNO3 uptake is smaller than that observed here for the C15 and C18 fatty acid monolayers.

  10. The effect of fatty acid surfactants on the uptake of nitric acid to deliquesced NaCl aerosol

    NASA Astrophysics Data System (ADS)

    Stemmler, K.; Vlasenko, A.; Guimbaud, C.; Ammann, M.

    2008-09-01

    Surface active organic compounds have been observed in marine boundary layer aerosol. Here, we investigate the effect such surfactants have on the uptake of nitric acid (HNO3), an important removal reaction of nitrogen oxides in the marine boundary layer. The uptake of gaseous HNO3 on deliquesced NaCl aerosol was measured in a flow reactor using HNO3 labelled with the short-lived radioactive isotope 13N. The uptake coefficient γ on pure deliquesced NaCl aerosol was γ=0.5±0.2 at 60% relative humidity and 30 ppb HNO3(g). The uptake coefficient was reduced by a factor of 5 50 when the aerosol was coated with saturated linear fatty acids with carbon chain lengths of 18 and 15 atoms in monolayer quantities. In contrast, neither shorter saturated linear fatty acids with 12 and 9 carbon atoms, nor coatings with the unsaturated oleic acid (C18, cis-double bond) had a detectable effect on the rate of HNO3 uptake. It is concluded that it is the structure of the monolayers formed, which determines their resistance towards HNO3 uptake. Fatty acids (C18 and C15), which form a highly ordered film in the so-called liquid condensed state, represent a significant barrier towards HNO3 uptake, while monolayers of shorter-chain fatty acids (C9, C12) and of the unsaturated oleic acid form a less ordered film in the liquid expanded state and do not hinder the uptake. Similarly, high contents of humic acids in the aerosol, a structurally inhomogeneous, quite water soluble mixture of oxidised high molecular weight organic compounds did not affect HNO3 uptake. As surfactant films on naturally occurring aerosol are expected to be less structured due to their chemical inhomogeneity, it is likely that their inhibitory effect on HNO3 uptake is smaller than that observed here for the C15 and C18 fatty acid monolayers.

  11. Growth hormone enhances amino acid uptake by the human small intestine.

    PubMed Central

    Inoue, Y; Copeland, E M; Souba, W W

    1994-01-01

    OBJECTIVE: The effects of growth hormone (GH) on the luminal transport of amino acids and glucose by the human small intestine were investigated. SUMMARY BACKGROUND DATA: The anabolic effect of growth hormone administration is associated with nitrogen retention and an increase muscle strength, but the impact of growth hormone on nutrient uptake from the gut lumen has not been examined. METHODS: Twelve healthy patients received a daily subcutaneous dose of low-dose GH (0.1 mg/kg), high-dose GH (0.2 mg/kg), or no treatment (controls) for 3 days before surgery. At operation, ileum (8 patients) or jejunum (4 patients) was resected, and brush border membrane vesicles (BBMVs) were prepared by differential centrifugation. Vesicle purity was confirmed by a 16-fold enrichment of marker enzymes. The carrier-mediated transport of glutamine (System B), leucine (System L), alanine (System B), arginine (System y+), MeAIB (methyl alpha-aminoisobutyric acid [System A]), and glucose (Na(+)-dependent glucose transporter) by BBMVs was measured by a rapid mixing/filtration technique. RESULTS: Treatment with low-dose GH resulted in a statistically insignificant increase in amino acid transport rates in jejunal and ileal BBMVs. High-dose GH resulted in a generalized 20%-to 70%-stimulation of amino acid transport, whereas glucose transport was not affected. The effects of GH were similar in ileum and jejunum. Kinetic analysis of the transport of glutamine (the most abundant amino acid in the body and the principal gut fuel) and the essential amino acid leucine revealed that the increase in transport was caused by a 50% increase in carrier Vmax, consistent with an increase in the number of functional carriers in the brush border membrane. Pooled analysis of transport velocities demonstrated that total rates of amino acid uptake from the gut lumen were increased significantly by 35% in GH-treated patients. CONCLUSIONS: The ability of GH to enhance amino acid uptake from the gut lumen

  12. Root uptake of cationic amino acids by Arabidopsis depends on functional expression of amino acid permease 5.

    PubMed

    Svennerstam, Henrik; Ganeteg, Ulrika; Näsholm, Torgny

    2008-01-01

    * Specific transporters mediate uptake of amino acids by plant roots. Earlier studies have indicated that the lysine histidine transporter 1 and amino acid permease 1 participate in this process, but although plant roots have been shown to absorb cationic amino acids with high affinity, neither of these transporters seems to mediate transport of L-arginine (L-Arg) or L-lysine (L-Lys). * Here, a collection of T-DNA knockout mutants were screened for alterations in Arabidopsis root uptake rates of L-Arg and it was found that only the AAP5 mutant displayed clear phenotypic divergence on high concentrations of L-Arg. A second screen using low concentrations of (15)N-labelled L-Arg in the growth media also identified AAP5 as being involved in L-Arg acquisition. * Momentaneous root uptake of basic amino acids was strongly affected in AAP5 mutant lines, but their uptake of other types of amino acids was only marginally affected. Comparisons of the root uptake characteristics of AAP5 and LHT1 mutants corroborated the hypothesis that the two transporters have distinct affinity spectra in planta. * Root uptake of all tested amino acids, except L-aspartic acid (L-Asp), was significantly affected in double AAP5*LHT1 mutants, suggesting that these two transporters account for a major proportion of roots' uptake of amino acids at low concentrations. PMID:18681934

  13. Real-time quantification of fatty acid uptake using a novel fluorescence assay.

    PubMed

    Liao, Jinfang; Sportsman, Richard; Harris, Jeff; Stahl, Andreas

    2005-03-01

    Uptake of nonesterified long-chain fatty acids (LCFAs) into many cell types and organs such as liver, heart, intestine, and skeletal muscle occurs primarily through a saturable, protein-mediated mechanism. Membrane proteins that increase the uptake of LCFAs, such as FAT/CD36 and fatty acid transport proteins, represent significant therapeutic targets for the treatment of metabolic disorders, including type 2 diabetes. However, currently available methods for the quantification of LCFA uptake neither allow for real-time measurements of uptake kinetics nor are ideally suited for the development of LCFA uptake inhibitors in high-throughput screens. To address both problems, we developed a LCFA uptake assay using a fluorescently labeled fatty acid and a nontoxic cell-impermeable quenching agent that allows fatty acid transport to be measured in real time using fluorescence plate readers or standard fluorescence microscopy. With this assay, we faithfully reproduced known differentiation- and hormone-induced changes in LCFA uptake by 3T3-L1 cells and determined LCFA uptake kinetics with previously unobtainable temporal resolution. Applications of this novel assay should facilitate new insights into the biology of fatty acid uptake and provide new means for obesity-related drug discovery. PMID:15547301

  14. Development of amino acid uptake activity in Neurospora.

    PubMed

    Railey, R M; Kinsey, J A

    1976-02-01

    During the germination and growth of Neurospora conidia, amino acid permease systems I (neutral) and II (general) increase in specific activity. System III (basic) decreases in specific activity with the onset of germination. System I shows two peaks of activity during the logarithmic phase of growth. One peak occurs at 6 h, the other at 12 h of growth. Both peaks are abolished in the mtr mutant. Both peaks have a Km for phenylalanine of 40 muM. The peaks of system I activity appear to correlate with morphological changes. PMID:4208

  15. Reactive uptake of N2O5 by aerosols containing dicarboxylic acids. Effect of particle phase, composition, and nitrate content.

    PubMed

    Griffiths, Paul T; Badger, Claire L; Cox, R Anthony; Folkers, Mareike; Henk, Hartmut H; Mentel, Thomas F

    2009-04-30

    Reactive uptake coefficients for loss of N(2)O(5) to micron-size aerosols containing oxalic malonic, succinic, and glutaric acids, and mixtures with ammonium hydrogen sulfate and ammonium sulfate, are presented. The uptake measurements were made using two different systems: atmospheric pressure laminar flow tube reactor (Cambridge) and the Large Indoor Aerosol Chamber at Forschungszentrum Juelich. Generally good agreement is observed for the data recorded using the two techniques. Measured uptake coefficients lie in the range 5 x 10(-4)-3 x 10(-2), dependent on relative humidity, on particle phase, and on particle composition. Uptake to solid particles is generally slow, with observed uptake coefficients less than 1 x 10(-3), while uptake to liquid particles is around an order of magnitude more efficient. These results are rationalized using a numerical model employing explicit treatment of both transport and chemistry. Our results indicate a modest effect of the dicarboxylic acids on uptake and confirm the strong effect of particle phase, liquid water content, and particulate nitrate concentrations. PMID:19385680

  16. Uptake of Ambient Organic Gases to Acidic Sulfate Aerosols

    NASA Astrophysics Data System (ADS)

    Liggio, J.; Li, S.

    2009-05-01

    The formation of secondary organic aerosols (SOA) in the atmosphere has been an area of significant interest due to its climatic relevance, its effects on air quality and human health. Due largely to the underestimation of SOA by regional and global models, there has been an increasing number of studies focusing on alternate pathways leading to SOA. In this regard, recent work has shown that heterogeneous and liquid phase reactions, often leading to oligomeric material, may be a route to SOA via products of biogenic and anthropogenic origin. Although oligomer formation in chamber studies has been frequently observed, the applicability of these experiments to ambient conditions, and thus the overall importance of oligomerization reactions remain unclear. In the present study, ambient air is drawn into a Teflon smog chamber and exposed to acidic sulfate aerosols which have been formed in situ via the reaction of SO3 with water vapor. The aerosol composition is measured with a High Resolution Aerodyne Aerosol Mass Spectrometer (HR-ToF-AMS), and particle size distributions are monitored with a scanning mobility particle sizer (SMPS). The use of ambient air and relatively low inorganic particle loading potentially provides clearer insight into the importance of heterogeneous reactions. Results of experiments, with a range of sulfate loadings show that there are several competing processes occurring on different timescales. A significant uptake of ambient organic gases to the particles is observed immediately followed by a slow shift towards higher m/z over a period of several hours indicating that higher molecular weight products (possibly oligomers) are being formed through a reactive process. The results suggest that heterogeneous reactions can occur with ambient organic gases, even in the presence of ammonia, which may have significant implications to the ambient atmosphere where particles may be neutralized after their formation.

  17. Long-chain polyunsaturated fatty acids stimulate cellular fatty acid uptake in human placental choriocarcinoma (BeWo) cells.

    PubMed

    Johnsen, G M; Weedon-Fekjaer, M S; Tobin, K A R; Staff, A C; Duttaroy, A K

    2009-12-01

    Supplementation of long-chain polyunsaturated fatty acids (LCPUFAs) is advocated during pregnancy in some countries although very little information is available on their effects on placental ability to take up these fatty acids for fetal supply to which the fetal growth and development are critically dependent. To identify the roles of LCPUFAs on placental fatty acid transport function, we examined the effects of LCPUFAs on the uptake of fatty acids and expression of fatty acid transport/metabolic genes using placental trophoblast cells (BeWo). Following 24 h incubation of these cells with 100 microM of LCPUFAs (arachidonic acid, 20:4n-6, eicosapentaenoic acid, 20:5n-3, or docosahexaenoic acid, 22:6n-3), the cellular uptake of [(14)C] fatty acids was increased by 20-50%, and accumulated fatty acids were preferentially incorporated into phospholipid fractions. Oleic acid (OA, 18:1n-9), on the other hand, could not stimulate fatty acid uptake. LCPUFAs and OA increased the gene expression of ADRP whilst decreased the expression of ASCL3, ACSL4, ACSL6, LPIN1, and FABP3 in these cells. However, LCPUFAs but not OA increased expression of ACSL1 and ACSL5. Since acyl-CoA synthetases are involved in cellular uptake of fatty acids via activation for their channelling to lipid metabolism and/or for storage, the increased expression of ACSL1 and ACLS5 by LCPUFAs may be responsible for the increased fatty acid uptake. These findings demonstrate that LCPUFA may function as an important regulator of general fatty acid uptake in trophoblast cells and may thus have impact on fetal growth and development. PMID:19880178

  18. Nutrient uptake by protocells: a liposome model system.

    PubMed

    Monnard, P A; Deamer, D W

    2001-01-01

    Over the past decade, several liposome-based models for protocells have been developed. For example, liposome systems composed of polymerase enzymes encapsulated with their substrates have demonstrated that complex compartmentalized reactions can be carried out under conditions in which polymeric products are protected from degradation by hydrolytic enzymes present in the external medium. However, such systems do not have nutrient uptake mechanisms, which would be essential for primitive cells lacking the highly evolved nutrient transport processes present in all contemporary cells. In this report, we explore passive diffusion of solutes across lipid bilayers as one possible uptake mechanism. We have established conditions under which ionic substrates as large as ATP can permeate bilayers at rates capable of supplying an encapsulated template-dependent RNA polymerase. Furthermore, while allowing the permeation of monomer substrates such as ATP, bilayer vesicles selectively retained polymerization products as small as dimers and as large as a transfer RNA. These observations demonstrate that passive diffusion could be used by the earliest forms of cellular life for transport of important nutrients such as amino acids, phosphate, and phosphorylated organic solutes. PMID:11296517

  19. Nutrient Uptake by Protocells: A Liposome Model System

    NASA Astrophysics Data System (ADS)

    Monnard, Pierre-Alain; Deamer, David W.

    2001-02-01

    Over the past decade, several liposome-based models for protocells have been developed. For example, liposome systems composed of polymerase enzymes encapsulated with their substrates have demonstrated that complex compartmentalized reactions can be carried out under conditions in which polymeric products are protected from degradation by hydrolytic enzymes present in the external medium. However, such systems do not have nutrient uptake mechanisms, which would be essential for primitive cells lacking the highly evolved nutrient transport processes present in all contemporary cells. In this report, we explore passive diffusion of solutes across lipid bilayers as one possible uptake mechanism. We have established conditions under which ionic substrates as large as ATP can permeate bilayers at rates capable of supplying an encapsulated template-dependent RNA polymerase. Furthermore, while allowing the permeation of monomer substrates such as ATP, bilayer vesicles selectively retained polymerization products as small as dimers and as large as a transfer RNA. These observations demonstrate that passive diffusion could be used by the earliest forms of cellular life for transport of important nutrients such as amino acids, phosphate, and phosphorylated organic solutes.

  20. A serotonergic system in veins: serotonin transporter-independent uptake.

    PubMed

    Linder, A Elizabeth; Ni, Wei; Szasz, Theodora; Burnett, Robert; Diaz, Jessica; Geddes, Timothy J; Kuhn, Donald M; Watts, Stephanie W

    2008-06-01

    We hypothesized that the 5-hydroxytryptamine (5-HT; serotonin) system is present and functional in veins. In vena cava (VC), the presence of the 5-HT synthesis rate-limiting enzyme tryptophan hydroxylase-1 mRNA and accumulation of the 5-HT synthesis intermediate 5-hydroxytryptophan after incubation with tryptophan supported the ability of veins to synthesize 5-HT. The presence of 5-HT and its metabolite 5-hydroxyindole acetic acid was measured by high-performance liquid chromatography in VC and jugular vein (JV), and it was compared with similarly sized arteries aorta (RA) and carotid (CA), respectively. In rats treated with the monoamine oxidase-A (MAO-A) inhibitor pargyline to prevent 5-HT metabolism, basal 5-HT levels were higher in veins than in arteries. 5-HT uptake was observed after exposure to exogenous 5-HT in all vessels. The presence of MAO-A and the 5-HT transporter (SERT) in VC was observed by immunohistochemistry and Western analysis. However, 5-HT uptake was not inhibited by the SERT inhibitors fluoxetine and/or fluvoxamine in VC and JV, as opposed to the inhibition in RA and CA. Moreover, studies performed in VC from mutant rats lacking SERT showed no differences in 5-HT uptake compared with VC from wild type. These data suggest the SERT is not functional under physiological conditions in veins. The differences in 5-HT handling between veins and arteries may represent alternative avenues for targeting the 5-HT system in the peripheral circulation for controlling vascular tone. PMID:18322152

  1. Identification of multiple cellular uptake pathways of polystyrene nanoparticles and factors affecting the uptake: relevance for drug delivery systems.

    PubMed

    Firdessa, Rebuma; Oelschlaeger, Tobias A; Moll, Heidrun

    2014-01-01

    Nanoparticles may address challenges by human diseases through improving diagnosis, vaccination and treatment. The uptake mechanism regulates the type of threat a particle poses on the host cells and how a cell responds to it. Hence, understanding the uptake mechanisms and cellular interactions of nanoparticles at the cellular and subcellular level is a prerequisite for their effective biomedical applications. The present study shows the uptake mechanisms of polystyrene nanoparticles and factors affecting their uptake in bone marrow-derived macrophages, 293T kidney epithelial cells and L929 fibroblasts. Labeling with the endocytic marker FM4-64 and transmission electron microscopy studies show that the nanoparticles were internalized rapidly via endocytosis and accumulated in intracellular vesicles. Soon after their internalizations, nanoparticles trafficked to organelles with acidic pH. Analysis of the ultrastructural morphology of the plasma membrane invaginations or extravasations provides clear evidence for the involvement of several uptake routes in parallel to internalize a given type of nanoparticles by mammalian cells, highlighting the complexity of the nanoparticle-cell interactions. Blocking the specific endocytic pathways by different pharmacological inhibitors shows similar outcomes. The potential to take up nanoparticles varies highly among different cell types in a particle sizes-, time- and energy-dependent manner. Furthermore, infection and the activation status of bone marrow-derived macrophages significantly affect the uptake potential of the cells, indicating the need to understand the diseases' pathogenesis to establish effective and rational drug-delivery systems. This study enhances our understanding of the application of nanotechnology in biomedical sciences. PMID:25224362

  2. Increased brain uptake of gamma-aminobutyric acid in a rabbit model of hepatic encephalopathy

    SciTech Connect

    Bassett, M.L.; Mullen, K.D.; Scholz, B.; Fenstermacher, J.D.; Jones, E.A. )

    1990-03-01

    Transfer of the inhibitory neurotransmitter gamma-aminobutyric acid across the normal blood-brain barrier is minimal. One prerequisite for gamma-aminobutyric acid in plasma contributing to the neural inhibition of hepatic encephalopathy would be that increased transfer of gamma-aminobutyric acid across the blood-brain barrier occurs in liver failure. The aim of the present study was to determine if brain gamma-aminobutyric acid uptake is increased in rabbits with stage II-III (precoma) hepatic encephalopathy due to galactosamine-induced fulminant hepatic failure. A modification of the Oldendorf intracarotid artery-injection technique was applied. (3H) gamma-aminobutyric acid, (14C) butanol, and 113mIn-labeled serum protein (transferrin) were injected simultaneously 4 s before decapitation. The ipsilateral brain uptake index of gamma-aminobutyric acid was determined from measurements of the 3 isotopes in 5 brain regions. Uncorrected or simple brain uptake indices of (3H) gamma-aminobutyric acid and (113mIn) transferrin were calculated using (14C) butanol as the highly extracted reference compound. The (113mIn) transferrin data were also used to correct the brain uptake index of (3H) gamma-aminobutyric acid for intravascular retention of (3H) gamma-aminobutyric acid. The methodology adopted minimized problems attributable to rapid (3H) gamma-aminobutyric acid metabolism, and slow brain washout and recirculation of the radiolabeled tracers. Both the uncorrected and corrected brain uptake indices of gamma-aminobutyric acid as well as the simple brain uptake index of transferrin were significantly increased in both stage II and III hepatic encephalopathy in all brain regions studied. Moreover, these brain uptake indices were significantly greater in stage III hepatic encephalopathy than in stage II hepatic encephalopathy.

  3. Effects of hydrostatic pressure and temperature on the uptake and respiration of amino acids by a facultatively psychrophilic marine bacterium.

    NASA Technical Reports Server (NTRS)

    Paul, K. L.; Morita, R. Y.

    1971-01-01

    Studies of pressure and temperature effects on glutamic acid transport and utilization indicated that hydrostatic pressure and low temperature inhibit glutamate transport more than glutamate respiration. The effects of pressure on transport were reduced at temperatures near the optimum. Similar results were obtained for glycine, phenylalanine, and proline. Pressure effects on the transport systems of all four amino acids were reversible to some degree. Both proline and glutamic acid were able to protect their transport proteins against pressure damage. The data presented indicate that the uptake of amino acids by cells under pressure is inhibited, which is the cause of their inability to grow under pressure.

  4. On the Nutritive Significance of Dissolved Free Amino Acid Uptake for the Cosmopolitan Oligochaete Nais elinguisMüller (Naididae)

    NASA Astrophysics Data System (ADS)

    Petersen, S.; Arlt, G.; Faubel, A.; Carman, K. R.

    1998-01-01

    Uptake of dissolved free amino acids (DFAA) byNais elinguisMüller from a brackish water lagoon has been confirmed by autoradiographic studies, liquid scintillation counting of animals incubated with labelled DFAA, and by HPLC analysis of the incubation water. Net uptake was shown to occur at ambient DFAA concentrations. The results indicate that most of the absorbed DFAA were respired, and only a minor portion was incorporated into proteins. Parallel determination of respiration and DFAA uptake in a flow-through system allowed a calculation of the contribution of uptake to the maintainance metabolism ofN. elinguis. The average weight-specific uptake rate of mixed DFAA was 1·4 μmol g-1h-1at a salinity of 6 and 4·1 μmol g-1h-1at a salinity of 12 (temperature 20 °C). Assuming that 10 μmol of mixed amino acids (average mol wt. 100) require 44·64 μmol O2for complete oxidation, the nutritional profit of DFAA absorption at a salinity of 6 accounted for 7% of the total oxidative needs and for 24% at a salinity of 12. The results demonstrate that DFAA uptake can provide an important nutritional input.

  5. Characterization of the catecholamine uptake system in PC12

    SciTech Connect

    Koide, M.

    1988-01-01

    The catecholamine uptake system of PC12 was characterized. PC12 cells took up both norepinephrine (NE) and dopamine (DA) from the external medium. Uptake of both substances had Na/sup +/-dependent and Na/sup +/-independent portions. The Na/sup +/-dependent portion followed Michaelis-Menten kinetics. For NE the K/sub m/ was 0.5 ..mu..M, and the V/sub max/ was 2.7 pmol min/sup -1/ (mg protein)/sup -1/. For DA the K/sub m/ was 0.2 ..mu..M and the V/sub max/ was 3.8 pmol min/sup -1/ (mg protein)/sup -1/. The uptake of both substances was inhibited by desmethylimipramine with an IC/sub 50/ of 0.01 ..mu..M and by benztropine with an IC/sub 50/ of 1 ..mu..M. These results suggest that NE and DA are transported by the same uptake system. Xylamine (N-2-chloroethyl-N-ethyl-2-methylbenzylamine) irreversibly inhibited the NE uptake (IC/sub 50/ = 15 ..mu..M). This inhibitions was Na/sup +/-dependent and was prevented by the coincubation of xylamine with cocaine or NE during the exposure of the cells to xylamine. These results indicate that xylamine must interact with the functioning NE uptake system to inhibit the uptake. PC12 accumulated (/sup 3/H)xylamine; this uptake had Na/sup +/-dependent and Na/sup +/-independent portions.

  6. A defect in sodium-dependent amino acid uptake in diabetic rabbit peripheral nerve. Correction by an aldose reductase inhibitor or myo-inositol administration.

    PubMed Central

    Greene, D A; Lattimer, S A; Carroll, P B; Fernstrom, J D; Finegold, D N

    1990-01-01

    A myo-inositol-related defect in nerve sodium-potassium ATPase activity in experimental diabetes has been suggested as a possible pathogenetic factor in diabetic neuropathy. Because the sodium-potassium ATPase is essential for other sodium-cotransport systems, and because myo-inositol-derived phosphoinositide metabolites regulate multiple membrane transport processes, sodium gradient-dependent amino acid uptake was examined in vitro in endoneurial preparations derived from nondiabetic and 14-d alloxan diabetic rabbits. Untreated alloxan diabetes reduced endoneurial sodium-gradient dependent uptake of the nonmetabolized amino acid 2-aminoisobutyric acid by greater than 50%. Administration of an aldose reductase inhibitor prevented reductions in both nerve myo-inositol content and endoneurial sodium-dependent 2-aminoisobutyric acid uptake. Myo-inositol supplementation that produced a transient pharmacological elevation in plasma myo-inositol concentration, but did not raise nerve myo-inositol content, reproduced the effect of the aldose reductase inhibitor on endoneurial sodium-dependent 2-aminoisobutyric acid uptake. Phorbol myristate acetate, which acutely normalizes sodium-potassium ATPase activity in diabetic nerve, did not acutely correct 2-aminoisobutyric uptake when added in vitro. These data suggest that depletion of a small myo-inositol pool may be implicated in the pathogenesis of defects in amino acid uptake in diabetic nerve and that rapid correction of sodium-potassium ATPase activity with protein kinase C agonists in vitro does not acutely normalize sodium-dependent 2-aminoisobutyric acid uptake. PMID:2185278

  7. Uptake of Hypobromous Acid (HOBr) by Aqueous Sulfuric Acid Solutions: Low-Temperature Solubility and Reaction

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Michelsen, Rebecca R.; Ashbourn, Samatha F. M.; Rammer, Thomas A.; Golden, David M.

    2005-01-01

    Hypobromous acid (HOBr) is a key species linking inorganic bromine to the chlorine and odd hydrogen chemical families. We have measured the solubility of HOBr in 45 - 70 wt% sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosol composition. Over the temperature range 201 - 252 K, HOBr is quite soluble in sulfuric acid, with an effective Henry's law coefficient, H* = 10(exp 4) - 10(exp 7) mol/L/atm. H* is inversely dependent on temperature, with Delta H = -46.2 kJ/mol and Delta S = -106.2 J/mol/K for 55 - 70 wt% H2SO4 solutions. Our study includes temperatures which overlap both previous measurements of HOBr solubility. For uptake into aqueous 45 wt% H2SO4, the solubility can be described by log H* = 3665/T - 10.63. For 55 - 70 wt% H2SO4, log H* = 2412/T - 5.55. At temperatures colder than approx. 213 K, the solubility of HOBr in 45 wt% H2SO4 is noticeably larger than in 70 wt% H2SO4. The solubility of HOBr is comparable to that of HBr, indicating that upper tropospheric and lower stratospheric aerosols should contain equilibrium concentrations of HOBr which equal or exceed those of HBr. Our measurements indicate chemical reaction of HOBr upon uptake into aqueous sulfuric acid in the presence of other brominated gases followed by evolution of gaseous products including Br2O and Br2, particularly at 70 wt% H2SO4.

  8. Elevated sacroilac joint uptake ratios in systemic lupus erythematosus

    SciTech Connect

    De Smet, A.A.; Mahmood, T.; Robinson, R.G.; Lindsley, H.B.

    1984-08-01

    Sacroiliac joint radiographs and radionuclide sacroiliac joint uptake ratios were obtained on 14 patients with active systemic lupus erythematosus. Elevated joint ratios were found unilaterally in two patients and bilaterally in seven patients when their lupus was active. In patients whose disease became quiescent, the uptake ratios returned to normal. Two patients had persistently elevated ratios with continued clinical and laboratory evidence of active lupus. Mild sacroiliac joint sclerosis and erosions were detected on pelvic radiographs in these same two patients. Elevated quantitative sacroiliac joint uptake ratios may occur as a manifestation of active systemic lupus erythematosus.

  9. Identification of the lrp gene in Bradyrhizobium japonicum and its role in regulation of delta-aminolevulinic acid uptake.

    PubMed Central

    King, N D; O'Brian, M R

    1997-01-01

    The heme precursor delta-aminolevulinic acid (ALA) is taken up by the dipeptide permease (Dpp) system in Escherichia coli. In this study, we identified a Bradyrhizobium japonicum genomic library clone that complemented both ALA and dipeptide uptake activities in E. coli dpp mutants. The complementing B. japonicum DNA encoded a product with 58% identity to the E. coli global transcriptional regulator Lrp (leucine-responsive regulatory protein), implying the presence of Dpp-independent ALA uptake activity in those cells. Data support the conclusion that the Lrp homolog induced the oligopeptide permease system in the complemented cells by interfering with the repressor activity of the endogenous Lrp, thus conferring oligopeptide and ALA uptake activities. ALA uptake by B. japonicum was effectively inhibited by a tripeptide and, to a lesser extent, by a dipeptide, and a mutant strain that expressed the lrp homolog from a constitutive promoter was deficient in ALA uptake activity. The data show that Lrp negatively affects ALA uptake in E. coli and B. japonicum. Furthermore, the product of the isolated B. japonicum gene is both a functional and structural homolog of E. coli Lrp, and thus the regulator is not restricted to enteric bacteria. PMID:9045849

  10. Uptake and utilization of dissolved free amino acids by the brittlestar Microphiopholis gracillima (Say, 1852) (Echinodermata: Ophiuroidea) during disc regeneration

    SciTech Connect

    Clements, L.A.J.

    1988-01-01

    Dissolved organic material (DOM) may be especially important to marine organisms unable to feed due to lack of a digestive system, injury or autotomy. Disc autotomy by the brittlestar Microphiopholis gracillima includes loss of the gut and gonads, and precludes ingestion of particulate food by the animal until gut regeneration is complete. The influence of DOM on the rate of disc regeneration by autotomized M. gracillima was tested by incubating animals in artificial seawater containing different concentrations of amino acids. Rates of uptake of amino acids and excretion of amino acids, ammonia and urea by intact and regenerating M. gracillima individuals were quantified using high performance liquid chromatography. Uptake and catabolism of leucine and glycine were examined using radioisotopic techniques. Both intact and regenerating M. gracillima increased their uptake of {sup 14}C-glycine with starvation, but rates of uptake were higher for intact animals. Catabolism of leucine and glycine, as evidenced by release of labeled CO{sub 2}, was highest among intact animals indicating that the amino acids were being used as energy sources during starvation. However, regenerating animals catabolized less than 2% of the labeled glycine acquired from seawater.

  11. Improved cadmium uptake and accumulation in the hyperaccumulator Sedum alfredii: the impact of citric acid and tartaric acid* #

    PubMed Central

    Lu, Ling-li; Tian, Sheng-ke; Yang, Xiao-e; Peng, Hong-yun; Li, Ting-qiang

    2013-01-01

    The elucidation of a natural strategy for metal hyperaccumulation enables the rational design of technologies for the clean-up of metal-contaminated soils. Organic acid has been suggested to be involved in toxic metallic element tolerance, translocation, and accumulation in plants. The impact of exogenous organic acids on cadmium (Cd) uptake and translocation in the zinc (Zn)/Cd co-hyperaccumulator Sedum alfredii was investigated in the present study. By the addition of organic acids, short-term (2 h) root uptake of 109Cd increased significantly, and higher 109Cd contents in roots and shoots were noted 24 h after uptake, when compared to controls. About 85% of the 109Cd taken up was distributed to the shoots in plants with citric acid (CA) treatments, as compared with 75% within controls. No such effect was observed for tartaric acid (TA). Reduced growth under Cd stress was significantly alleviated by low CA. Long-term application of the two organic acids both resulted in elevated Cd in plants, but the effects varied with exposure time and levels. The results imply that CA may be involved in the processes of Cd uptake, translocation and tolerance in S. alfredii, whereas the impact of TA is mainly on the root uptake of Cd. PMID:23365009

  12. Improved cadmium uptake and accumulation in the hyperaccumulator Sedum alfredii: the impact of citric acid and tartaric acid.

    PubMed

    Lu, Ling-li; Tian, Sheng-ke; Yang, Xiao-e; Peng, Hong-yun; Li, Ting-qiang

    2013-02-01

    The elucidation of a natural strategy for metal hyperaccumulation enables the rational design of technologies for the clean-up of metal-contaminated soils. Organic acid has been suggested to be involved in toxic metallic element tolerance, translocation, and accumulation in plants. The impact of exogenous organic acids on cadmium (Cd) uptake and translocation in the zinc (Zn)/Cd co-hyperaccumulator Sedum alfredii was investigated in the present study. By the addition of organic acids, short-term (2 h) root uptake of (109)Cd increased significantly, and higher (109)Cd contents in roots and shoots were noted 24 h after uptake, when compared to controls. About 85% of the (109)Cd taken up was distributed to the shoots in plants with citric acid (CA) treatments, as compared with 75% within controls. No such effect was observed for tartaric acid (TA). Reduced growth under Cd stress was significantly alleviated by low CA. Long-term application of the two organic acids both resulted in elevated Cd in plants, but the effects varied with exposure time and levels. The results imply that CA may be involved in the processes of Cd uptake, translocation and tolerance in S. alfredii, whereas the impact of TA is mainly on the root uptake of Cd. PMID:23365009

  13. A phospholipid uptake system in the model plant Arabidopsis thaliana.

    PubMed

    Poulsen, Lisbeth R; López-Marqués, Rosa L; Pedas, Pai R; McDowell, Stephen C; Brown, Elizabeth; Kunze, Reinhard; Harper, Jeffrey F; Pomorski, Thomas G; Palmgren, Michael

    2015-01-01

    Plants use solar energy to produce lipids directly from inorganic elements and are not thought to require molecular systems for lipid uptake from the environment. Here we show that Arabidopsis thaliana Aminophospholipid ATPase10 (ALA10) is a P4-type ATPase flippase that internalizes exogenous phospholipids across the plasma membrane, after which they are rapidly metabolized. ALA10 expression and phospholipid uptake are high in the epidermal cells of the root tip and in guard cells, the latter of which regulate the size of stomatal apertures to modulate gas exchange. ALA10-knockout mutants exhibit reduced phospholipid uptake at the root tips and guard cells and are affected in growth and transpiration. The presence of a phospholipid uptake system in plants is surprising. Our results suggest that one possible physiological role of this system is to internalize lysophosphatidylcholine, a signalling lipid involved in root development and stomatal control. PMID:26212235

  14. Compensatory Root Water Uptake of Overlapping Root Systems

    NASA Astrophysics Data System (ADS)

    Agee, E.; Ivanov, V. Y.; He, L.; Bisht, G.; Shahbaz, P.; Fatichi, S.; Gough, C. M.; Couvreur, V.; Matheny, A. M.; Bohrer, G.

    2015-12-01

    Land-surface models use simplified representations of root water uptake based on biomass distributions and empirical functions that constrain water uptake during unfavorable soil moisture conditions. These models fail to capture the observed hydraulic plasticity that allows plants to regulate root hydraulic conductivity and zones of active uptake based on local gradients. Recent developments in root water uptake modeling have sought to increase its mechanistic representation by bridging the gap between physically based microscopic models and computationally feasible macroscopic approaches. It remains to be demonstrated whether bulk parameterization of microscale characteristics (e.g., root system morphology and root conductivity) can improve process representation at the ecosystem scale. We employ the Couvreur method of microscopic uptake to yield macroscopic representation in a coupled soil-root model. Using a modified version of the PFLOTRAN model, which represents the 3-D physics of variably saturated soil, we model a one-hectare temperate forest stand under natural and synthetic climatic forcing. Our results show that as shallow soil layers dry, uptake at the tree and stand level shift to deeper soil layers, allowing the transpiration stream demanded by the atmosphere. We assess the potential capacity of the model to capture compensatory root water uptake. Further, the hydraulic plasticity of the root system is demonstrated by the quick response of uptake to rainfall pulses. These initial results indicate a promising direction for land surface models in which significant three-dimensional information from large root systems can be feasibly integrated into the forest scale simulations of root water uptake.

  15. Interactions between uptake of amino acids and inorganic nitrogen in wheat plants

    NASA Astrophysics Data System (ADS)

    Gioseffi, E.; de Neergaard, A.; Schjoerring, J. K.

    2012-04-01

    Soil-borne amino acids may constitute a source of nitrogen (N) for plants in various terrestrial ecosystems but their importance for total N nutrition is unclear, particularly in nutrient-rich arable soils. One reason for this uncertainty is lack of information on how the absorption of amino acids by plant roots is affected by the simultaneous presence of inorganic N forms. The objective of the present study was to study absorption of glycine (Gly) and glutamine (Gln) by wheat roots and their interactions with nitrate (NO3-) and ammonium (NH4+) during uptake. The underlying hypothesis was that amino acids, when present in nutrient solution together with inorganic N, may lead to down-regulation of the inorganic N uptake, thereby resulting in similar total N uptake rates. Amino acids were enriched with double-labelled 15N and 13C, while NO3- and NH4+ acquisition was determined by their rate of removal from the nutrient solution surrounding the roots. The uptake rates of NO3- and NH4+ did not differ from each other and were generally about twice as high as the uptake rate of organic N when the different N forms were supplied separately in concentrations of 2 mM. Nevertheless, replacement of 50% of the inorganic N with organic N was able to restore the N uptake to the same level as that in the presence of only inorganic N. Co-provision of NO3- did not affect glycine uptake, while the presence of glycine down-regulated NO3- uptake. The ratio between 13C and 15N were lower in shoots than in roots and also lower than the theoretical values, reflecting higher C losses via respiratory processes compared to N losses. It is concluded that organic N can constitute a significant N-source for wheat plants and that there is an interaction between the uptake of inorganic and organic N.

  16. Uptake of Acidic and Basic Sugar Derivatives in Lemna gibba G1 1

    PubMed Central

    Sanz, Amparo; Ullrich, Cornelia I.

    1989-01-01

    The uptake of acidic and basic sugar derivatives in Lemna gibba L. was studied. Uronic acids applied to the experimental solution (50 millimolar) induced a small decrease of the membrane potential (10 ± 1 millivolt galacturonic acid, and 20 ± 4 millivolt glucuronic acid). After incubation of the plants in a 0.1 millimolar solution of these substrates, no decrease in the concentration of reducing groups in the external solution was detected. Respiration increased by 31% with 50 millimolar galacturonic acid, whereas no effect was found with the same concentration of glucuronic acid. Glucosamine caused a considerable concentration-dependent membrane depolarization. (14C)glucosamine uptake followed Michaelis-Menten kinetics together with a linear component. Influx of this substrate was inhibited by glucose but the type of competition could not be clearly distinguished. Glucosamine, 50 millimolar, inhibited the respiration rate by 30%. The glucosamine uptake was pH-dependent, with maximum uptake at around pH 7. Lack of enhancement of uptake by low pH as well as the permanent membrane depolarization suggest a uniport mechanism for the charged species of the substrate and an electroneutral diffusion of the uncharged species. PMID:16666961

  17. EFFECT OF HUMIC ACID ON UPTAKE AND TRANSFER OF COPPER FROM MICROBES TO CILIATES TO COPEPODS

    EPA Science Inventory

    This research is part of an ongoing project designed to determine the effect of humic acid on the uptake and transfer of metals by marine organisms at the lower end of the food chain. Binding affinities for Cu, Cd, Zn, and Cr to Suwannee River humic acid were determined at variou...

  18. An observing system simulation for Southern Ocean carbon dioxide uptake.

    PubMed

    Majkut, Joseph D; Carter, Brendan R; Frölicher, Thomas L; Dufour, Carolina O; Rodgers, Keith B; Sarmiento, Jorge L

    2014-07-13

    The Southern Ocean is critically important to the oceanic uptake of anthropogenic CO2. Up to half of the excess CO2 currently in the ocean entered through the Southern Ocean. That uptake helps to maintain the global carbon balance and buffers transient climate change from fossil fuel emissions. However, the future evolution of the uptake is uncertain, because our understanding of the dynamics that govern the Southern Ocean CO2 uptake is incomplete. Sparse observations and incomplete model formulations limit our ability to constrain the monthly and annual uptake, interannual variability and long-term trends. Float-based sampling of ocean biogeochemistry provides an opportunity for transforming our understanding of the Southern Ocean CO2 flux. In this work, we review current estimates of the CO2 uptake in the Southern Ocean and projections of its response to climate change. We then show, via an observational system simulation experiment, that float-based sampling provides a significant opportunity for measuring the mean fluxes and monitoring the mean uptake over decadal scales. PMID:24891388

  19. Fate and Uptake of Pharmaceuticals in Soil–Earthworm Systems

    PubMed Central

    2014-01-01

    Pharmaceuticals present a potential threat to soil organisms, yet our understanding of their fate and uptake in soil systems is limited. This study therefore investigated the fate and uptake of 14C-labeled carbamazepine, diclofenac, fluoxetine, and orlistat in soil–earthworm systems. Sorption coefficients increased in the order of carbamazepine < diclofenac < fluoxetine < orlistat. Dissipation of 14C varied by compound, and for orlistat, there was evidence of formation of nonextractable residues. Uptake of 14C was seen for all compounds. Depuration studies showed complete elimination of 14C for carbamazepine and fluoxetine treatments and partial elimination for orlistat and diclofenac, with greater than 30% of the 14C remaining in the tissue at the end of the experiment. Pore-water-based bioconcentration factors (BCFs), based on uptake and elimination of 14C, increased in the order carbamazepine < diclofenac < fluoxetine and orlistat. Liquid chromatography–tandem mass spectrometry and liquid chromatography–Fourier transform mass spectrometry indicated that the observed uptake in the fluoxetine and carbamazepine treatments was due to the parent compounds but that diclofenac was degraded in the test system so uptake was due to unidentifiable transformation products. Comparison of our data with outputs of quantitative structure−activity relationships for estimating BCFs in worms showed that these models tend to overestimate pharmaceutical BCFs so new models are needed. PMID:24762061

  20. Interactions between uptake of amino acids and inorganic nitrogen in wheat plants

    NASA Astrophysics Data System (ADS)

    Gioseffi, E.; de Neergaard, A.; Schjoerring, J. K.

    2011-11-01

    Soil-borne amino acids may constitute a nitrogen (N) source for plants in various terrestrial ecosystems but their importance for total N nutrition is unclear, particularly in nutrient-rich arable soils. One reason for this uncertainty is lack of information on how the absorption of amino acids by plant roots is affected by the simultaneous presence of inorganic N forms. The objective of the present study was to study absorption of glycine (Gly) and glutamine (Gln) by wheat roots and their interactions with nitrate (NO3-) and (NH4+) during uptake. The underlying hypothesis was that amino acids, when present in nutrient solution together with inorganic N, may lead to down-regulation of the inorganic N uptake. Amino acids were enriched with double-labelled 15N and 13C, while NO3- and NH4+ acquisition was determined by their rate of removal from the nutrient solution surrounding the roots. The uptake rates of NO3- and NH4+ did not differ from each other and were about twice as high as the uptake rate of organic N when the different N forms were supplied separately in concentrations of 2 mM. Nevertheless, replacement of 50 % of the inorganic N with organic N was able to restore the N uptake to the same level as that in the presence of only inorganic N. Co-provision of NO3- did not affect glycine uptake, while the presence of glycine down-regulated NO3- uptake. The ratio between 13C and 15N were lower in shoots than in roots and also lower than the theoretical values, reflecting higher C losses via respiratory processes compared to N losses. It is concluded that organic N can constitute a significant N-source for wheat plants and that there is an interaction between the uptake of inorganic and organic nitrogen.

  1. Effect of spermine on the uptake of amino acids in Micrococcus lysodeikticus.

    PubMed

    Ariel, M; Grossowicz, N

    1972-08-01

    Spermine inhibited the transport of neutral aliphatic amino acids (valine, leucine, isoleucine, alanine, and glycine) into cells of Micrococcus lysodeikticus. On the other hand, spermine did not affect the uptake of basic (arginine and histidine), acidic (glutamic acid), or aromatic (phenylalanine and tyrosine) amino acids. Inhibition of uptake of the neutral amino acids by spermine is apparently of a noncompetitive nature; the V(max) decreased, whereas the apparent K(m) remained unaltered. The inhibition is most likely due to a specific binding of spermine to the carrier(s) of these amino acids. Related polyamines, spermidine and cadaverine, also caused inhibition of valine uptake, though to a lesser extent; spermidine was less active than spermine, and cadaverine showed the weakest effect of all. Valine, leucine, and isoleucine were transported into M. lysodeikticus cells by a common carrier as evidenced from competition experiments. The uptake of these amino acids is an active process; it was temperature-dependent and inhibited by azide (10(-1)m to 2.5 x 10(-2)m) and dinitrophenol (10(-3)m). The intracellular concentration of valine was 100-fold higher than in the medium. PMID:5053465

  2. Uptake and Dissolution of Gaseous Ethanol in Sulfuric Acid

    NASA Technical Reports Server (NTRS)

    Michelsen, Rebecca R.; Staton, Sarah J. R.; Iraci, Laura T.

    2006-01-01

    The solubility of gas-phase ethanol (ethyl alcohol, CH3CH2OH, EtOH) in aqueous sulfuric acid solutions was measured in a Knudsen cell reactor over ranges of temperature (209-237 K) and acid composition (39-76 wt % H2SO4). Ethanol is very soluble under these conditions: effective Henry's law coefficients, H*, range from 4 x 10(exp 4) M/atm in the 227 K, 39 wt % acid to greater than 10(exp 7) M/atm in the 76 wt % acid. In 76 wt % sulfuric acid, ethanol solubility exceeds that which can be precisely determined using the Knudsen cell technique but falls in the range of 10(exp 7)-10(exp 10) M/atm. The equilibrium concentration of ethanol in upper tropospheric/lower stratospheric (UT/LS) sulfate particles is calculated from these measurements and compared to other small oxygenated organic compounds. Even if ethanol is a minor component in the gas phase, it may be a major constituent of the organic fraction in the particle phase. No evidence for the formation of ethyl hydrogen sulfate was found under our experimental conditions. While the protonation of ethanol does augment solubility at higher acidity, the primary reason H* increases with acidity is an increase in the solubility of molecular (i.e., neutral) ethanol.

  3. Atorvastatin Prevents Glutamate Uptake Reduction Induced by Quinolinic Acid Via MAPKs Signaling.

    PubMed

    Vandresen-Filho, S; Martins, W C; Bertoldo, D B; Rieger, D K; Maestri, M; Leal, R B; Tasca, C I

    2016-08-01

    Statins have been shown to promote neuroprotection in a wide range of neurological disorders. However, the mechanisms involved in such effects of statins are not fully understood. Quinolinic acid (QA) is a neurotoxin that induces seizures when infused in vivo and promotes glutamatergic excitotoxicity in the central nervous system. The aim of this study was to evaluate the putative glutamatergic mechanisms and the intracellular signaling pathways involved in the atorvastatin neuroprotective effects against QA toxicity. Atorvastatin (10 mg/kg) treatment for 7 days prevented the QA-induced decrease in glutamate uptake, but had no effect on increased glutamate release induced by QA. Moreover, atorvastatin treatment increased the phosphorylation of ERK1 and prevented the decrease in Akt phosphorylation induced by QA. Neither atorvastatin treatment nor QA infusion altered glutamine synthetase activity or the levels of phosphorylation of p38(MAPK) or JNK1/2 during the evaluation. Inhibition of MEK/ERK signaling pathway, but not PI3K/Akt signaling, abolished the neuroprotective effect of atorvastatin against QA-induced decrease in glutamate uptake. Our data suggest that atorvastatin protective effects against QA toxicity are related to modulation of glutamate transporters via MAPK/ERK signaling pathway. PMID:27084771

  4. pH-Dependent Uptake of Fumaric Acid in Saccharomyces cerevisiae under Anaerobic Conditions

    PubMed Central

    Jamalzadeh, Elaheh; Verheijen, Peter J. T.; Heijnen, Joseph J.

    2012-01-01

    Microbial production of C4 dicarboxylic acids from renewable resources has gained renewed interest. The yeast Saccharomyces cerevisiae is known as a robust microorganism and is able to grow at low pH, which makes it a suitable candidate for biological production of organic acids. However, a successful metabolic engineering approach for overproduction of organic acids requires an incorporation of a proper exporter to increase the productivity. Moreover, low-pH fermentations, which are desirable for facilitating the downstream processing, may cause back diffusion of the undissociated acid into the cells with simultaneous active export, thereby creating an ATP-dissipating futile cycle. In this work, we have studied the uptake of fumaric acid in S. cerevisiae in carbon-limited chemostat cultures under anaerobic conditions. The effect of the presence of fumaric acid at different pH values (3 to 5) has been investigated in order to obtain more knowledge about possible uptake mechanisms. The experimental results showed that at a cultivation pH of 5.0 and an external fumaric acid concentration of approximately 0.8 mmol · liter−1, the fumaric acid uptake rate was unexpectedly high and could not be explained by diffusion of the undissociated form across the plasma membrane alone. This could indicate the presence of protein-mediated import. At decreasing pH levels, the fumaric acid uptake rate was found to increase asymptotically to a maximum level. Although this observation is in accordance with protein-mediated import, the presence of a metabolic bottleneck for fumaric acid conversion under anaerobic conditions could not be excluded. PMID:22113915

  5. Retinoic acid treatment of fibroblasts causes a rapid decrease in ( sup 3 H)inositol uptake

    SciTech Connect

    Sinha, R.; Creek, K.E.; Silverman-Jones, C.; de Luca, L.M. )

    1989-04-01

    NIH 3T3 fibroblasts treated with all-trans-retinoic acid (RA) showed a dramatic decrease in the uptake of ({sup 3}H)inositol compared to solvent-treated controls. The onset of RA-induced inhibition of ({sup 3}H)inositol uptake was rapid with a 10-15% decrease occurring after 2-3 h of RA exposure and 60-70% reduction after 16 h of RA treatment. A progressive dose-dependent decrease in inositol uptake was found as the concentration of RA increased from 10{sup {minus}8} to 10{sup {minus}5} M and the effect was fully reversible within 48 h after RA removal. RA inhibition of inositol uptake was also observed in 3T3-Swiss and Balb/3T3 cells but not in two virally transformed 3T3 cell lines. Phlorizin, amiloride, and monensin inhibited inositol uptake by 66, 74, and 58%, respectively, and this inhibition was additive when the cells were treated with RA as well as these inhibitors. A decreased incorporation of ({sup 3}H)inositol into polyphosphoinositides was also observed in RA-treated cells but not to the same extent as for ({sup 3}H)inositol uptake. In conclusion, RA treatment of 3T3 fibroblasts decreases the uptake of ({sup 3}H)inositol by up to 70% within 8 to 10 h at near physiological concentrations in a reversible and specific manner.

  6. Laser photobioactivation mechanisms: In vitro studies using ascorbic acid uptake and hydroxyproline formation as biochemical markers of irradiation response

    SciTech Connect

    Labbe, R.F.; Skogerboe, K.J.; Davis, H.A.; Rettmer, R.L. )

    1990-01-01

    Clinical investigations of laser photobioactivation, or biostimulation, might be differently designed and more fruitful if knowledge of basic biochemical mechanisms were better understood. In this investigation, biochemical events identified as responses to 904 nm irradiation included increased ascorbic acid uptake by fibroblasts. These cells also showed increased hydroxyproline formation, and this was increased several-fold by the addition of proline to the medium. Maximum biochemical responses were observed at a pulse frequency of 67 Hz and a pulse width of 150 nsec with an energy density of approximately 7 mJ/cm2 per exposure. Elements in the mitochondrial cytochrome system are proposed as the radiation absorbing chromophore(s). Hypothetically, the energy generated is linked to ascorbic acid uptake, which in turn stimulates collagen synthesis.

  7. Effects of ammonium application rate on uptake of soil adsorbed amino acids by rice*

    PubMed Central

    Cao, Xiao-chuang; Ma, Qing-xu; Wu, Liang-huan; Zhu, Lian-feng; Jin, Qian-yu

    2016-01-01

    In recent years, excessive use of chemical nitrogen (N) fertilizers has resulted in the accumulation of excess ammonium (NH4 +) in many agricultural soils. Though rice is known as an NH4 +-tolerant species and can directly absorb soil intact amino acids, we still know considerably less about the role of high exogenous NH4 + content on rice uptake of soil amino acids. This experiment examined the effects of the exogenous NH4 + concentration on rice uptake of soil adsorbed glycine in two different soils under sterile culture. Our data showed that the sorption capacity of glycine was closely related to soils’ physical and chemical properties, such as organic matter and cation exchange capacity. Rice biomass was significantly inhibited by the exogenous NH4 + content at different glycine adsorption concentrations. A three-way analysis of variance demonstrated that rice glycine uptake and glycine nutritional contribution were not related to its sorption capacity, but significantly related to its glycine:NH4 + concentration ratio. After 21-d sterile cultivation, the rice uptake of adsorbed glycine accounted for 8.8%‒22.6% of rice total N uptake, which indicates that soil adsorbed amino acids theoretically can serve as an important N source for plant growth in spite of a high NH4 + application rate. However, further studies are needed to investigate the extent to which this bioavailability is realized in the field using the 13C, 15N double labeling technology.

  8. Hyaluronic acid uptake in the assessment of sinusoidal endothelial cell damage after cold storage and normothermic reperfusion of rat livers.

    PubMed

    Reinders, M E; van Wagensveld, B A; van Gulik, T M; Frederiks, W M; Chamuleau, R A; Endert, E; Klopper, P J

    1996-01-01

    The uptake of hyaluronic acid (HA) was used to assess preservation damage to sinusoidal endothelial cells (SEC) during cold storage and subsequent normothermic reperfusion of rat livers. After 8, 16, 24, and 48 h storage in University of Wisconsin (UW) solution, livers were gravity-flushed via the portal vein with a standard volume of cold UW solution containing 50 micrograms/l HA. The effluent was collected for analysis of HA, aspartate aminotransferase (AST), and lactate dehydrogenase (LDH). The mean uptake of HA at 0 h was 59.1% +/- 4.6% (mean +/- SEM). After 8 h of storage, HA uptake was similar (55.5% +/- 7.3%), whereas after 16 h of storage it was reduced to 34.7% +/- 5.8%. At 24 and 48 h of storage, no uptake of HA was found. In a second series of experiments, livers were stored in UW solution and subsequently reperfused for 90 min with a Krebs-Henseleit solution (37 degrees C) in a recirculating system containing 150 micrograms/l HA. Following 8 h of storage, 34.6% +/- 8.0% of the initial HA concentration was taken up from the perfusate. After 16 and 24 h of storage, no uptake of HA was found. The results of this study indicate that damage to SEC occurs progressively during storage, leading to zero uptake of HA by the rat livers at 24 h of cold ischemia time. Additional reperfusion injury to the SEC was demonstrated by the reduced ability of the SEC to take up HA following normothermic reperfusion. The uptake of exogenous HA in preserved livers, used as a tool to assess SEC injury, enables the detection of early preservation damage. PMID:8875786

  9. Uptake of nitric acid by sub-micron-sized ice particles

    NASA Astrophysics Data System (ADS)

    Arora, O. P.; Cziczo, D. J.; Morgan, A. M.; Abbatt, J. P. D.; Niedziela, R. F.

    The uptake of gas phase nitric acid by half-micron-diameter ice crystals has been studied at 230 K by measuring the nitrate content of ice particles which have been exposed to 5 × 10-6 torr of nitric acid in a low temperature flow tube. A cold NaOH-coated denuder is used to distinguish gas-phase nitric acid from adsorbed nitric acid. Ice particle diameters were determined by fitting measured aerosol infrared extinction spectra to spectra calculated via Mie theory, and their number density is measured directly with a CN counter. Under conditions in which the surface is saturated and not all the gas-phase nitric acid adsorbs, the measured uptakes are 1.2 × 1014 molecules/cm² where the surface area is the geometric area of the particles. Within experimental uncertainties, this surface coverage is the same as that measured on thin films of ice formed by freezing liquid water. These results are the first quantitative study of the nitric acid uptake capacity of ice particles, and they provide additional support to the suggestion that ice and snow provide a route for the efficient scavenging of nitric acid from the atmosphere.

  10. Comparison of the autoradiographic binding distribution of [3H]-gabapentin with excitatory amino acid receptor and amino acid uptake site distributions in rat brain.

    PubMed Central

    Thurlow, R. J.; Hill, D. R.; Woodruff, G. N.

    1996-01-01

    1. Gabapentin is a novel anticonvulsant with an unknown mechanism of action. Recent homogenate binding studies with [3H]-gabapentin have suggested a structure-activity relationship similar to that shown for the amino acid transport system responsible for the uptake of large neutral amino acids (LNAA). 2. The autoradiographic binding distribution of [3H]-gabapentin in rat brain was compared with the distributions for excitatory amino acid receptor subtypes and the uptake sites for excitatory and large neutral amino acids in consecutive rat brain sections. 3. Densitometric measurement of the autoradiographic images followed by normalisation with respect to the hippocampus CA1 stratum radiatum, was carried out before comparison of each binding distribution with that of [3H]-gabapentin by linear regression analysis. The correlation coefficients observed showed no absolute correlation was observed between the binding distributions of [3H]-gabapentin and those of the excitatory amino acid receptor subtypes. The acidic and large neutral amino acid uptake site distributions demonstrated a much closer correlation to the [3H]-gabapentin binding site distribution. The correlation coefficients for D-[3H]-aspartate, L-[3H]-leucine and L-[3H]-isoleucine binding site distributions were 0.76, 0.90 and 0.88 respectively. 4. Concentration-dependent inhibition by unlabelled gabapentin of autoradiographic binding of L-[3H]-leucine and L-[3H]-isoleucine was observed, with non-specific binding levels being reached at concentrations between 10 and 100 microM. 5. Excitotoxic quinolinic acid lesion studies in rat brain caudate putamen and autoradiography were carried out for the amino acid uptake sites mentioned above. The resulting glial infiltration of the lesioned areas was visualized by autoradiography using the peripheral benzodiazepine receptor specific ligand [3H]-PK11195. A significant decrease in binding density in the lesioned area compared with sham-operated animals was observed

  11. Non-Mendelian Mutation Allowing Ureidosuccinic Acid Uptake in Yeast

    PubMed Central

    Lacroute, Francois

    1971-01-01

    Mutants of Saccharomyces cerevisiae capable of growth on a minimal medium supplemented with ureidosuccinic and glutamic acids have been isolated from a pyrimidineless strain. One of these mutants consistently yielded a non-Mendelian meiotic segregation. Moreover, the mitotic transmission of the mutation was very high. It is suggested that the mutation is nonchromosomal and could be mitochondrial. However, this mutation behaves very differently from other mitochondrial mutations. PMID:5573734

  12. Biochemical Characterization of Branched Chain Amino Acids Uptake in Trypanosoma cruzi.

    PubMed

    Manchola, Nubia C; Rapado, Ludmila N; Barisón, María J; Silber, Ariel M

    2016-05-01

    Trypanosoma cruzi is the etiological agent of Chagas disease. During its life cycle, it alternates among vertebrate and invertebrate hosts. Metabolic flexibility is a main biochemical characteristic of this parasite, which is able to obtain energy by oxidizing a variety of nutrients that can be transported from the extracellular medium. Moreover, several of these metabolites, more specifically amino acids, have a variety of functions beyond being sources of energy. Branched chain amino acids (BCAA), beyond their role in ATP production, are involved in sterol biosynthesis; for example, leucine is involved as a negative regulator of the parasite differentiation process occurring in the insect midgut. BCAA are essential metabolites in most nonphotosynthetic eukaryotes, including trypanosomes. In view of this, the metabolism of BCAA in T. cruzi depends mainly on their transport into the cell. In this work, we kinetically characterized the BCAA transport in T. cruzi epimastigotes. Our data point to BCAA as being transported by a single saturable transport system able to recognize leucine, isoleucine and valine. In view of this, we used leucine to further characterize this system. The transport increased linearly with temperature from 10 to 45 °C, allowing the calculation of an activation energy of 51.30 kJ/mol. Leucine uptake was an active process depending on ATP production and a H(+) gradient, but not on a Na(+) or K(+) gradient at the cytoplasmic membrane level. PMID:26496801

  13. The importance of epithelial uptake systems in lung toxicity

    SciTech Connect

    Smith, L.L.; Lewis, C.P.L.; Wyatt, I. ); Cohen, G.M. )

    1990-04-01

    The discovery that the herbicide paraquat was selectively accumulated by the lung, both in vivo and in vitro, in comparison with other tissues, provided an explanation for its selective toxicity to the lung. This uptake process is energy dependent and obeys saturation kinetics. A characterization of the process led to the identification of endogenous chemicals that are the natural substrates for the system. Among these are a series of diamines and polyamines, as well as the diaminodisulfide cystamine. It appears that paraquat, because of specific structural similarities to these endogenous polyamines, is mistakenly accumulated by the lung. This uptake process is specifically located in the alveolar Type II cell, the Clara cell, and probably the alveolar Type I cell. With the development of knowledge of the structural requirements of chemicals to be accumulated by this system, it is possible to predict which chemicals will be accumulated by the lung or design molecules that are targeted to the alveolar epithelial and Clara cells. In the wider perspective, this polyamine uptake system has been found on a number of cancerous cells or tissues. With the knowledge of the uptake system in the lung, it should be possible to design drugs that will be specifically concentrated in cells that possess this system.

  14. Nitric Acid Uptake on Subtropical Cirrus Cloud Particles

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The redistribution of HNO3 via uptake and sedimentation by cirrus cloud particles is considered an important term in the upper tropospheric budget of reactive nitrogen. Numerous cirrus cloud encounters by the NASA WB-57F high-altitude research aircraft during CRYSTAL-FACE were accompanied by the observation of condensed-phase HNO3 with the NOAA chemical ionization mass spectrometer. The instrument measures HNO3 with two independent channels of detection connected to separate forward- and downward-facing inlets that allow a determination of the amount of HNO3 condensed on ice particles. Subtropical cirrus clouds, as indicated by the presence of ice particles, were observed coincident with condensed-phase HNO3 at temperatures of 197 K - 224 K and pressures of 122 hPa - 224 hPa. Maximum levels of condensed-phase HNO3 approached the gas-phase equivalent of 0.8 ppbv. Ice particle surface coverages as high as 1.4- 10(exp 14) molecules/sq cm were observed. A dissociative Langmuir adsorption model, when using an empirically derived HNO3 adsorption enthalpy of -11.0 kcal/mol, effectively describes the observed molecular coverages to within a factor of 5. The percentage of total HNO3 in the condensed phase ranged from near zero to 100% in the observed cirrus clouds. With volume-weighted mean particle diameters up to 700 pm and particle fall velocities up to 10 m/s, some observed clouds have significant potential to redistribute HNO3 in the upper troposphere.

  15. Nitric Acid Uptake on Subtropical Cirrus Cloud Particles

    NASA Technical Reports Server (NTRS)

    Popp, P. J.; Gao, R. S.; Marcy, T. P.; Fahey, D. W.; Hudson, P. K.; Thompson, T. L.; Kaercher, B.; Ridley, B. A.; Weinheimer, A. J.; Knapp, D. J.; Montzka, D. D.; Baumgardner, D.; Garrett, T. J.; Weinstock, E. M.; Smith, J. B.; Sayres, D. S.; Pittman, J. V.; Dhaniyala, S.; Bui, T. P.; Mahoney, M. J.

    2004-01-01

    The redistribution of HNO3 via uptake and sedimentation by cirrus cloud particles is considered an important term in the upper tropospheric budget of reactive nitrogen. Numerous cirrus cloud encounters by the NASA WB-57F high-altitude research aircraft during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) were accompanied by the observation of condensed-phase HNO3 with the NOAA chemical ionization mass spectrometer. The instrument measures HNO3 with two independent channels of detection connected to separate forward and downward facing inlets that allow a determination of the amount of HNO3 condensed on ice particles. Subtropical cirrus clouds, as indicated by the presence of ice particles, were observed coincident with condensed-phase HNO3 at temperatures of 197-224 K and pressures of 122-224 hPa. Maximum levels of condensed-phase HNO3 approached the gas-phase equivalent of 0.8 ppbv. Ice particle surface coverages as high as 1.4 # 10(exp 14) molecules/ square cm were observed. A dissociative Langmuir adsorption model, when using an empirically derived HNO3 adsorption enthalpy of -11.0 kcal/mol, effectively describes the observed molecular coverages to within a factor of 5. The percentage of total HNO3 in the condensed phase ranged from near zero to 100% in the observed cirrus clouds. With volume-weighted mean particle diameters up to 700 ?m and particle fall velocities up to 10 m/s, some observed clouds have significant potential to redistribute HNO3 in the upper troposphere.

  16. The role of citric acid in cadmium and nickel uptake and translocation, in Halimione portulacoides.

    PubMed

    Duarte, Bernardo; Delgado, Marta; Caçador, Isabel

    2007-10-01

    Some plants have high ability to absorb heavy metals in high concentrations. In this study, Halimione portulacoides was tested in conjunction with citric acid, in order to evaluate the possible use of this plant in phytoremediation processes in salt marshes. Two different concentrations of chelator were used combined with two heavy metal concentrations. When 25microM of citric acid was applied, Cd uptake and translocation was enhanced while for Ni these processes were almost inhibited. Increasing citric acid concentration to 50microM, Ni absorption decreased by the roots while for Cd there was still an increase in root uptake. Analysing translocation with this concentration of chelator, a decreased metal content in the upper organs for both metals was observed. While for Cd an optimal concentration of 25microM of citric acid was observed for phytoremediative processes, for nickel neither concentrations of chelator showed advantages for application in this remediative method. PMID:17585999

  17. Uptake and/or utilization of two simple phenolic acids by Cucumis sativus

    SciTech Connect

    Shann, J.R.

    1986-01-01

    The uptake of ferulic acid (FA) and p-hydroxybenzoic acid (p-HBA) from solutions (0.1 to 1.00 mM, pH 4.0 to 7.0), was determined for intact and excised roots of Cucumis sativus. Uptake methods based on high performance liquid chromatographic (HPLC) analysis of phenolic acid depletion from solution were compared to those radioisotopic methods employing (U-ring-/sup 14/C)FA or p-HBA. Although radiotracer methods more accurately reflected actual uptake of the compounds by cucumber seedlings, HPLC solution depletion methods may be useful in the elucidation of trends over very limited periods of time. The uptake of FA was unaffected by the presence of p-HBA. The uptake of p-HBA was reduced by 30% in the presence of FA when compared to the uptake from solutions containing p-HBA alone. Ferulic acid acts both as an allelopathic agent and precursor in the endogenous process of lignification. To evaluate the involvement of exogenous FA in lignin biosynthesis, roots of hydroponically grown cucumber seedlings were exposed to concentrations of FA labeled with (U-ring-/sup 14/C)FA. Radiotracer was distributed throughout the seedling. A quantitative change in lignification occurred in treated seedlings. In roots and stems, the level of lignin increased with the number of exposures and as the concentrations of exogenous FA increased. Radiotracer was found in the residues of lignin isolated from seedling tissue treated with (U-ring-/sup 14/C)FA. This suggested the utilization of the exogenously applied FA in the endogenous process of lignification.

  18. Impact of Mistletoe Triterpene Acids on the Uptake of Mistletoe Lectin by Cultured Tumor Cells

    PubMed Central

    Mulsow, Katharina; Enzlein, Thomas; Delebinski, Catharina; Jaeger, Sebastian; Seifert, Georg; Melzig, Matthias F.

    2016-01-01

    Complementary treatment possibilities for the therapy of cancer are increasing in demand due to the severe side effects of the standard cytostatics used in the first-line therapy. A common approach as a complementary treatment is the use of aqueous extracts of Viscum album L. (Santalaceace). The therapeutic activity of these extracts is attributed to Mistletoe lectins which are Ribosome-inactivating proteins type II. Besides these main constituents the extract of Viscum album L. comprises also a mixture of lipophilic ingredients like triterpene acids of the oleanane, lupane and ursane type. However, these constituents are not contained in commercially available aqueous extracts due to their high lipophilicity and insolubility in aqueous extraction media. To understand the impact of the extract ingredients in cancer therapy, the intracellular uptake of the mistletoe lectin I (ML) by cultured tumor cells was investigated in relation to the mistletoe triterpene acids, mainly oleanolic acid. Firstly, these hydrophobic triterpene acids were solubilized using cyclodextrins (“TT” extract). Afterwards, the uptake of either single compounds (isolated ML and the aqueous “viscum” extract) or in combination with the TT extract (ML+TT, viscumTT), was analyzed. The uptake of ML was studied inTHP-1-, HL-60-, 143B- and Ewing TC-71-cells and determined after 30, 60 and 120 minutes by an enzyme linked immunosorbent assay which quantifies the A-chain of the hololectin. It could be shown that the intracellular uptake after 120 minutes amounted to 20% in all cell lines after incubation with viscumTT. The studies further revealed that the uptake in THP-1-, HL-60- and Ewing TC-71-cells was independent of the addition of TT extract. Interestingly, the uptake of ML by 143B-cells could only be measured after addition of triterpenes pointing to resistance to mistletoe lectin. PMID:27088729

  19. [Effect of cholinomimetics on L-glutamic acid release and uptake in the neostriatum of rats].

    PubMed

    Godukhin, O V; Budantsev, A Iu; Selifonova, O V; Agapova, V N

    1983-12-01

    The effects of cholinomimetics on release and uptake of exogenic glutamic acid in the rat brain neostriatum in vivo and in vitro were studied. Carbocholine and nicotin were shown to inhibit the release, carbocholine acting directly on the presynaptic receptors whereas nicotin acting indirectly through the interneurons of neostriatum. PMID:6141074

  20. UPTAKE AND METABOLISM OF ALL-TRANS RETINOIC ACID BY THREE NATIVE NORTH AMERICAN RANIDS

    EPA Science Inventory

    Retinoids, which are Vvitamin A derivatives, are important signaling molecules that regulate processes critical for development in all vertebrates. The objective of our study was to examine uptake and metabolism of the model retinoid, all-trans retinoic acid (all-trans RA), by th...

  1. Evaluation of [11C]oseltamivir uptake into the brain during immune activation by systemic polyinosine-polycytidylic acid injection: a quantitative PET study using juvenile monkey models of viral infection

    PubMed Central

    2014-01-01

    Background Abnormal behaviors of young patients after taking the anti-influenza agent oseltamivir (Tamiflu®, F. Hoffmann-La Roche, Ltd., Basel, Switzerland) have been suspected as neuropsychiatric adverse events (NPAEs). Immune response to viral infection is suspected to cause elevation of drug concentration in the brain of adolescents. In the present study, the effect of innate immune activation on the brain uptake of [11C]oseltamivir was quantitatively evaluated in juvenile monkeys. Methods Three 2-year-old monkeys underwent positron emission tomography (PET) scans at baseline and immune-activated conditions. Both scans were conducted under pre-dosing of clinically relevant oseltamivir. The immune activation condition was induced by the intravenous administration of polyinosine-polycytidylic acid (poly I:C). Dynamic [11C]oseltamivir PET scan and serial arterial blood sampling were performed to obtain [11C]oseltamivir kinetics. Brain uptake of [11C]oseltamivr was evaluated by its normalized brain concentration, brain-to-plasma concentration ratio, and plasma-to-brain transfer rate. Plasma pro-inflammatory cytokine levels were also measured. Results Plasma interleukin-6 was elevated after intravenous administration of poly I:C in all monkeys. Brain radioactivity was uniform both at baseline and under poly I:C treatment. The mean brain concentrations of [11C]oseltamivir were 0.0033 and 0.0035% ID/cm3 × kg, the mean brain-to-plasma concentration ratios were 0.58 and 0.65, and the plasma-to-brain transfer rates were 0.0047 and 0.0051 mL/min/cm3 for baseline and poly I:C treatment, respectively. Although these parameters were slightly changed by immune activation, the change was not notable. Conclusions The brain uptake of [11C]oseltamivir was unchanged by poly I:C treatment in juvenile monkeys. This study demonstrated that the innate immune response similar to the immune activation of influenza would not notably change the brain concentration of oseltamivir in

  2. The role of L-type amino acid transporters in the uptake of glyphosate across mammalian epithelial tissues.

    PubMed

    Xu, Jiaqiang; Li, Gao; Wang, Zhuoyi; Si, Luqin; He, Sijie; Cai, Jialing; Huang, Jiangeng; Donovan, Maureen D

    2016-02-01

    Glyphosate is one of the most commonly used herbicides worldwide due to its broad spectrum of activity and reported low toxicity to humans. Glyphosate has an amino acid-like structure that is highly polar and shows low bioavailability following oral ingestion and low systemic toxicity following intravenous exposures. Spray applications of glyphosate in agricultural or residential settings can result in topical or inhalation exposures to the herbicide. Limited systemic exposure to glyphosate occurs following skin contact, and pulmonary exposure has also been reported to be low. The results of nasal inhalation exposures, however, have not been evaluated. To investigate the mechanisms of glyphosate absorption across epithelial tissues, the permeation of glyphosate across Caco-2 cells, a gastrointestinal epithelium model, was compared with permeation across nasal respiratory and olfactory tissues excised from cows. Saturable glyphosate uptake was seen in all three tissues, indicating the activity of epithelial transporters. The uptake was shown to be ATP and Na(+) independent, and glyphosate permeability could be significantly reduced by the inclusion of competitive amino acids or specific LAT1/LAT2 transporter inhibitors. The pattern of inhibition of glyphosate permeability across Caco-2 and nasal mucosal tissues suggests that LAT1/2 play major roles in the transport of this amino-acid-like herbicide. Enhanced uptake into the epithelial cells at barrier mucosae, including the respiratory and gastrointestinal tracts, may result in more significant local and systemic effects than predicted from glyphosate's passive permeability, and enhanced uptake by the olfactory mucosa may result in further CNS disposition, potentially increasing the risk for brain-related toxicities. PMID:26701683

  3. Dietary ellagic acid attenuates oxidized LDL uptake and stimulates cholesterol efflux in murine macrophages.

    PubMed

    Park, Sin-Hye; Kim, Jung-Lye; Lee, Eun-Sook; Han, Seon-Young; Gong, Ju-Hyun; Kang, Min-Kyung; Kang, Young-Hee

    2011-11-01

    Foam cell formation is the hallmark of early atherosclerosis. Lipid uptake by scavenger receptors (SR) in macrophages initiates chronic proinflammatory cascades linked to atherosclerosis. It has been reported that the upregulation of cholesterol efflux may be protective in the development of atherosclerosis. Ellagic acid, a polyphenolic compound mostly found in berries, walnuts, and pomegranates, possesses antioxidative, growth-inhibiting and apoptosis-promoting activities in cancer cells. However, the antiatherogenic actions of ellagic acid are not well defined. The current study elucidated oxidized LDL handling of ellagic acid in J774A1 murine macrophages. Noncytotoxic ellagic acid suppressed SR-B1 induction and foam cell formation within 6 h after the stimulation of macrophages with oxidized LDL, confirmed by Oil red O staining of macrophages. Ellagic acid at ≤5 μmol/L upregulated PPARγ and ATP binding cassette transporter-1 in lipid-laden macrophages, all responsible for cholesterol efflux. In addition, 5 μmol/L ellagic acid accelerated expression and transcription of the nuclear receptor of liver X receptor-α highly implicated in the PPAR signaling. Furthermore, ellagic acid promoted cholesterol efflux in oxidized LDL-induced foam cells. These results provide new information that ellagic acid downregulated macrophage lipid uptake to block foam cell formation of macrophages and boosted cholesterol efflux in lipid-laden foam cells. Therefore, dietary and pharmacological interventions with berries rich in ellagic acid may be promising treatment strategies to interrupt the development of atherosclerosis. PMID:21940512

  4. Viscosity controls humidity dependence of N2O5 uptake to citric acid aerosol

    NASA Astrophysics Data System (ADS)

    Gržinić, G.; Bartels-Rausch, T.; Berkemeier, T.; Türler, A.; Ammann, M.

    2015-12-01

    The heterogeneous loss of dinitrogen pentoxide (N2O5) to aerosol particles has a significant impact on the night-time nitrogen oxide cycle and therefore the oxidative capacity in the troposphere. Using a 13N short-lived radioactive tracer method, we studied the uptake kinetics of N2O5 on citric acid aerosol particles as a function of relative humidity (RH). The results show that citric acid exhibits lower reactivity than similar dicarboxylic and polycarboxylic acids, with uptake coefficients between ∼ 3 × 10-4-∼ 3 × 10-3 depending on humidity (17-70 % RH). At RH above 50 %, the magnitude and the humidity dependence can be best explained by the viscosity of citric acid as compared to aqueous solutions of simpler organic and inorganic solutes and the variation of viscosity with RH and, hence, diffusivity in the organic matrix. Since the diffusion rates of N2O5 in highly concentrated citric acid solutions are not well established, we present four different parameterizations of N2O5 diffusivity based on the available literature data or estimates for viscosity and diffusivity of H2O. Above 50 % RH, uptake is consistent with the reacto-diffusive kinetic regime whereas below 50 % RH, the uptake coefficient is higher than expected from hydrolysis of N2O5 within the bulk of the particles, and the uptake kinetics is most likely limited by loss on the surface only. This study demonstrates the impact of viscosity in highly oxidized and highly functionalized secondary organic aerosol material on the heterogeneous chemistry of N2O5 and may explain some of the unexpectedly low loss rates to aerosol derived from field studies.

  5. Role of organic anion-transporting polypeptides for cellular mesalazine (5-aminosalicylic acid) uptake.

    PubMed

    König, Jörg; Glaeser, Hartmut; Keiser, Markus; Mandery, Kathrin; Klotz, Ulrich; Fromm, Martin F

    2011-06-01

    The therapeutic effects and metabolism of mesalazine (5-aminosalicylic acid) in patients with inflammatory bowel disease require intracellular accumulation of the drug in intestinal epithelial cells and hepatocytes. The molecular mechanisms of mesalazine uptake into cells have not been characterized so far. Using human embryonic kidney cells stably expressing uptake transporters of the organic anion-transporting polypeptide (OATP) family, which are expressed in human intestine and/or liver, we found that mesalazine uptake is mediated by OATP1B1, OATP1B3, and OATP2B1 but not by OATP1A2 and OATP4A1. Moreover, genetic variations (*1b, *5, *15) in the SLCO1B1 gene encoding OATP1B1 reduced the K(m) value for mesalazine uptake from 55.1 to 16.3, 24.3, and 32.4 μM, respectively, and the respective V(max) values. Finally, budesonide, cyclosporine, and rifampin were identified as inhibitors of OATP1B1-, OATP1B3-, and OATP2B1-meditated mesalazine uptake. These in vitro data indicate that OATP-mediated uptake and its modification by genetic factors and comedications may play a role for mesalazine effects. PMID:21430235

  6. Uptake of 4-chloro-2-methylphenoxyacetic acid (MCPA) from the apical membrane of Caco-2 cells by the monocarboxylic acid transporter

    SciTech Connect

    Kimura, Osamu; Tsukagoshi, Kensuke; Endo, Tetsuya

    2008-03-15

    The cellular uptake mechanism of 4-chloro-2-methylphenoxyacetic acid (MCPA), a phenoxyacetic acid derivative, was investigated using Caco-2 epithelial cells. The cells were incubated with 50 {mu}M MCPA at pH 6.0 and 37 deg. C, and the uptake of MCPA from the apical membranes was measured. The uptake of MCPA was significantly decreased by incubation at low temperature (4 {sup o}C) and markedly increased by lowering the extracellular pH. Pretreatment with a protonophore, carbonylcyanide-p-(trifluoromethoxy)phenylhydrazone (25 {mu}M), or metabolic inhibitors, 2,4-dinitrophenol (1 mM) and sodium azide (10 mM), significantly decreased the uptake of MCPA by 53%, 45% and 48%, respectively. Coincubation of MCPA with 10 mM L-lactic acid or {alpha}-cyano-4-hydroxycinnamate, which is a substrate or an inhibitor of the monocarboxylic acid transporters (MCTs), significantly decreased the uptake of MCPA by 31% and 20%, respectively, and coincubation with benzoic acid profoundly decreased the uptake by 68%. In contrast, coincubation with succinic acid (a dicarboxylic acid) did not affect the uptake. Kinetic analysis of initial MCPA uptake suggested that MCPA is taken up via a carrier-mediated process [K{sub m} = 1.37 {+-} 0.15 mM, V{sub max} = 115 {+-} 6 nmol (mg protein){sup -1} (3 min){sup -1}]. Lineweaver-Burk plots show that benzoic acid competitively inhibits the uptake of MCPA with a K{sub i} value of 4.68 {+-} 1.76 mM. A trans-stimulation effect on MCPA uptake was found in cells preloaded with benzoic acid. These results suggest that the uptake of MCPA from the apical membrane of Caco-2 cells is mainly mediated by common MCTs along with benzoic acid but also in part by L-lactic acid.

  7. Reactive uptake of N2O5 by aerosol particles containing mixtures of humic acid and ammonium sulfate.

    PubMed

    Badger, Claire L; Griffiths, Paul T; George, Ingrid; Abbatt, Jonathan P D; Cox, R Anthony

    2006-06-01

    The kinetics of reactive uptake of N2O5 on submicron aerosol particles containing humic acid and ammonium sulfate has been investigated as a function of relative humidity (RH) and aerosol composition using a laminar flow reactor coupled with a differential mobility analyzer (DMA) to characterize the aerosol. For single-component humic acid aerosol the uptake coefficient, gamma, was found to increase from 2 to 9 x 10(-4) over the range 25-75% RH. These values are 1-2 orders of magnitude below those typically observed for single-component sulfate aerosols (Phys. Chem. Chem. Phys. 2003, 5, 3453-3463;(1) Atmos. Environ. 2000, 34, 2131-2159(2)). For the mixed aerosols, gamma was found to decrease with increasing humic acid mass fraction and increase with increasing RH. For aerosols containing only 6% humic acid by dry mass, a decrease in reactivity of more than a factor of 2 was observed compared with the case for single-component ammonium sulfate. The concentration of liquid water in the aerosol droplets was calculated using the aerosol inorganic model (for the ammonium sulfate component) and a new combined FTIR-DMA system (for the humic acid component). Analysis of the uptake coefficients using the water concentration data shows that the change in reactivity cannot be explained by the change in water content alone. We suggest that, due to its surfactant properties, the main effect of the humic acid is to reduce the mass accommodation coefficient for N2O5 at the aerosol particle surface. This has implications for the use of particle hygroscopicity data for predictions of the rate of N2O5 hydrolysis. PMID:16722713

  8. Nonnutritive flow impairs uptake of fatty acid by white muscles of the perfused rat hindlimb.

    PubMed

    Clerk, L H; Smith, M E; Rattigan, S; Clark, M G

    2003-03-01

    Triglyceride hydrolysis by the perfused rat hindlimb is enhanced with serotonin-induced nonnutritive flow (NNF) and may be due to the presence of nonnutritive route-associated connective tissue fat cells. Here, we assess whether NNF influences muscle uptake of 0.55 mM palmitate in the perfused hindlimb. Comparisons were made with insulin-mediated glucose uptake. NNF induced during 60 nM insulin infusion inhibited hindlimb oxygen uptake from 22.0 +/- 0.5 to 9.7 +/- 0.8 micromol x g(-1) x h(-1) (P < 0.001), 1-methylxanthine metabolism (indicator of nutritive flow) from 5.8 +/- 0.4 to 3.8 +/- 0.4 nmol x min(-1) x g(-1) (P = 0.004), glucose uptake from 29.2 +/- 1.7 to 23.1 +/- 1.8 micromol x g(-1) x h(-1) (P = 0.005) and muscle 2-deoxyglucose uptake from 82.1 +/- 4.6 to 41.6 +/- 6.7 micromol x g(-1) x h(-1) (P < 0.001). Palmitate uptake, unaffected by insulin alone, was inhibited by NNF in extensor digitorum longus, white gastrocnemius, and tibialis anterior muscles; average inhibition was from 13.9 +/- 1.2 to 6.9 +/- 1.4 micromol x g(-1) x h(-1) (P = 0.02). Thus NNF impairs both fatty acid and glucose uptake by muscle by restricting flow to myocytes but, as shown previously, favors triglyceride hydrolysis and uptake into nearby connective tissue fat cells. The findings have implications for lipid partitioning in limb muscles between myocytes and attendant adipocytes. PMID:12453824

  9. Increased physical activity decreases hepatic free fatty acid uptake: a study in human monozygotic twins.

    PubMed

    Hannukainen, Jarna C; Nuutila, Pirjo; Borra, Ronald; Ronald, Borra; Kaprio, Jaakko; Kujala, Urho M; Janatuinen, Tuula; Heinonen, Olli J; Kapanen, Jukka; Viljanen, Tapio; Haaparanta, Merja; Rönnemaa, Tapani; Parkkola, Riitta; Knuuti, Juhani; Kalliokoski, Kari K

    2007-01-01

    Exercise is considered to be beneficial for free fatty acid (FFA) metabolism, although reports of the effects of increased physical activity on FFA uptake and oxidation in different tissues in vivo in humans have been inconsistent. To investigate the heredity-independent effects of physical activity and fitness on FFA uptake in skeletal muscle, the myocardium, and liver we used positron emission tomography (PET) in nine healthy young male monozygotic twin pairs discordant for physical activity and fitness. The cotwins with higher physical activity constituting the more active group had a similar body mass index but less body fat and 18 +/- 10% higher (P < 0.001) compared to the less active brothers with lower physical activity. Low-intensity knee-extension exercise increased skeletal muscle FFA and oxygen uptake six to 10 times compared to resting values but no differences were observed between the groups at rest or during exercise. At rest the more active group had lower hepatic FFA uptake compared to the less active group (5.5 +/- 4.3 versus 9.0 +/- 6.1 micromol (100 ml)(-1) min(-1), P = 0.04). Hepatic FFA uptake associated significantly with body fat percentage (P = 0.05). Myocardial FFA uptake was similar between the groups. In conclusion, in the absence of the confounding effects of genetic factors, moderately increased physical activity and aerobic fitness decrease body adiposity even in normal-weighted healthy young adult men. Further, increased physical activity together with decreased intra-abdominal adiposity seems to decrease hepatic FFA uptake but has no effects on skeletal muscle or myocardial FFA uptake. PMID:17053033

  10. Photoenhanced nitrous acid formation upon NO2 uptake on tannic and gentisic acid films

    NASA Astrophysics Data System (ADS)

    Sosedova, Yulia; Rouvière, Aurélie; Ammann, Markus

    2010-05-01

    The heterogeneous chemistry of nitrogen dioxide (NO2) is a potential source of nitrous acid (HONO). Hydroxy and methoxy substituted phenols may play a significant role in the aqueous-phase chemistry occurring on the ground or within aerosol particles in air masses affected by biomass burning. It is well established that electron transfer between phenols and NO2 in alkaline aqueous solutions is fast and could be a source of nitrite in the aqueous phase and HONO in the gas phase. However its kinetics is very slow under atmospheric conditions. The role of phenolic species as electron donors has also been suspected to be responsible for the photoenhanced transformation of NO2 to HONO over humic acids [1]. In this study we used tannic (TA) and gentisic (GA) as another proxy for atmospheric phenolic compounds. TA was shown to easily decompose under near UV light irradiation [2] resulting in oxidized products that might change the hygroscopic properties of the original material or have some potential photosensitizing effect. It was interesting to check the hypothesis that the presence of such products could lead to photoenhanced HONO formation upon NO2 uptake to aqueous surfaces containing TA. Experiments were performed in a horizontal coated wall flow tube (40 cm × 5.9 cm i.d.) circularly surrounded by 7 fluorescence lamps (UV: 300-420 nm, or visible: 400-750 nm), in an air cooled lamp housing. The inner surface coating was containing ~0.5 mg/cm-2 of either TA or GA, and was operated under RH 20-80%, 21-23 °C and ambient pressure. Concentration of HONO in the gas phase at the flow tube exit was measured with a LOPAP (Long Path Absorption Spectrometer). The uptake coefficient (γ) leading to NO2 to HONO conversion above aqueous films containing GA or TA in the dark was in the range 4×10-7 - 2×10-6. The photochemically enhanced HONO production was demonstrated by UV irradiation of the GA or TA coatings being in contact with gaseous NO2. In this case γ was 3-10 times

  11. Uptake of 13N-labeled N2O5 to citric acid aerosol particles

    NASA Astrophysics Data System (ADS)

    Grzinic, Goran; Bartels-Rausch, Thorsten; Birrer, Mario; Türler, Andreas; Ammann, Markus

    2013-04-01

    Dinitrogen pentoxide is a significant reactive intermediate in the night time chemistry of nitrogen oxides. Depending on atmospheric conditions it can act either as a NO3 radical reservoir or as a major NOx sink by heterogeneous hydrolysis on aerosol surfaces. As such, it can influence tropospheric ozone production and therefore the oxidative capacity of the atmosphere. Furthermore it's suspected of being a non negligible source of tropospheric Cl, even over continental areas [1,2]. We used the short-lived radioactive tracer 13N delivered by PSI's PROTRAC facility [3] in conjunction with an aerosol flow tube reactor in order to study N2O5 uptake kinetics on aerosol particles. 13NO is mixed with non labeled NO and O3 in a gas reactor where N2O5 is synthesized under dry conditions to prevent hydrolysis on the reactor walls. The resulting N2O5 flow is fed into an aerosol flow tube reactor together with a humidified aerosol flow. By using movable inlets we can vary the length of the aerosol flow tube and thus the reaction time. The gas feed from the reactor is then directed into a narrow parallel plate diffusion denuder system that allows for selective separation of the gaseous species present in the gas phase. Aerosol particles are trapped on a particle filter placed at the end of the denuder system. The activity of 13N labeled species trapped on the denuder plates and in the particle filter can be monitored via scintillation counters. Aerosol uptake measurements were performed with citric acid aerosols in a humidity range of 27-61.5% RH. The results obtained from our measurements have shown that the uptake coefficient increases with humidity from 1.65±0.3x10-3 (~27% RH) to 1.25±0.3x10-2 (45% RH) and 2.00±0.3x10-2 (61.5% RH). Comparison to literature data shows that this is similar to values reported for some polycarboxylic acids (like malonic acid), while being higher than some others [4]. The increase is likely related to the increasing amount of water associated

  12. Relationship of Cell Sap pH to Organic Acid Change During Ion Uptake 1

    PubMed Central

    Hiatt, A. J.

    1967-01-01

    Excised roots of barley (Hordeum vulgare, var. Campana) were incubated in KCl, K2SO4, CaCl2, and NaCl solutions at concentrations of 10−5 to 10−2 n. Changes in substrate solution pH, cell sap pH, and organic acid content of the roots were related to differences in cation and anion absorption. The pH of expressed sap of roots increased when cations were absorbed in excess of anions and decreased when anions were absorbed in excess of cations. The pH of the cell sap shifted in response to imbalances in cation and anion uptake in salt solutions as dilute as 10−5 n. Changes in cell sap pH were detectable within 15 minutes after the roots were placed in 10−3 n K2SO4. Organic acid changes in the roots were proportional to expressed sap pH changes induced by unbalanced ion uptake. Changes in organic acid content in response to differential cation and anion uptake appear to be associated with the low-salt component of ion uptake. PMID:16656506

  13. The Humidity Dependence of N2O5 Uptake to Citric Acid Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Grzinic, G.; Bartels-Rausch, T.; Tuerler, A.; Ammann, M.

    2013-12-01

    Dinitrogen pentoxide is a significant reactive intermediate in the night time chemistry of nitrogen oxides. Depending on atmospheric conditions it can act either as a NO3 radical reservoir or as a major NOx sink by heterogeneous hydrolysis on aerosol surfaces. As such, it can influence tropospheric ozone production and therefore the oxidative capacity of the atmosphere. The heterogeneous loss of N2O5 to aerosol particles has remained uncertain, and reconciling lab and field data has demonstrated some gaps in our understanding of the detailed mechanism. We used the short-lived radioactive tracer 13N to study N2O5 uptake kinetics on aerosol particles in an aerosol flow reactor at ambient pressure, temperature and relative humidity. Citric acid, representing strongly oxidized polyfunctional organic compounds in atmospheric aerosols, has been chosen as a proxy due to its well established physical properties. Aerosol uptake measurements were performed with citric acid aerosols in a humidity range of 15-75 % RH, within which the uptake coefficient varies between about 0.001 and about 0.02. Taking into account the well established hygroscopic properties of citric acid, we interpret uptake in terms of disproportionation of N2O5 into nitrate ion and nitronium ion and reaction of the latter with liquid water.

  14. Insulin effect on amino acid uptake by unloaded rat hindlimb muscles

    NASA Technical Reports Server (NTRS)

    Jaspers, S. R.; Tischler, M. E.

    1988-01-01

    The effect of insulin on the uptake of alpha-amino-isobutyric acid (AIB) by unloaded rat hindlimb muscles was investigated using soleus and extensor digitorum longus (EDL) muscles from intact and adrenalectomized (ADX) rats that were tail-casted for six days. It was found that, at insulin levels above 0.00001 units/ml, the in vitro rate of AIB uptake by muscles from intact animals was stimulated more in the weight bearing muscles than in unloaded ones. In ADX animals, this differential response to insulin was abolished.

  15. Uptake of Small Organic Compounds by Sulfuric Acid Aerosols: Dissolution and Reaction

    NASA Technical Reports Server (NTRS)

    Iraci, L. T.; Michelsen, R. R.; Ashbourn, S. F. M.; Staton, S. J. R.

    2003-01-01

    To assess the role of oxygenated volatile organic compounds in the upper troposphere and lower stratosphere, the interactions of a series of small organic compounds with low-temperature aqueous sulfuric acid will be evaluated. The total amount of organic material which may be taken up from the gas phase by dissolution, surface layer formation, and reaction during the particle lifetime will be quantified. Our current results for acetaldehyde uptake on 40 - 80 wt% sulfuric acid solutions will be compared to those of methanol, formaldehyde, and acetone to investigate the relationships between chemical functionality and heterogeneous activity. Where possible, equilibrium uptake will be ascribed to component pathways (hydration, protonation, etc.) to facilitate evaluation of other species not yet studied in low temperature aqueous sulfuric acid.

  16. Plant-uptake of uranium: Hydroponic and soil system studies

    USGS Publications Warehouse

    Ramaswami, A.; Carr, P.; Burkhardt, M.

    2001-01-01

    Limited information is available on screening and selection of terrestrial plants for uptake and translocation of uranium from soil. This article evaluates the removal of uranium from water and soil by selected plants, comparing plant performance in hydroponic systems with that in two soil systems (a sandy-loam soil and an organic-rich soil). Plants selected for this study were Sunflower (Helianthus giganteus), Spring Vetch (Vicia sativa), Hairy Vetch (Vicia villosa), Juniper (Juniperus monosperma), Indian Mustard (Brassica juncea), and Bush Bean (Phaseolus nanus). Plant performance was evaluated both in terms of the percent uranium extracted from the three systems, as well as the biological absorption coefficient (BAC) that normalized uranium uptake to plant biomass. Study results indicate that uranium extraction efficiency decreased sharply across hydroponic, sandy and organic soil systems, indicating that soil organic matter sequestered uranium, rendering it largely unavailable for plant uptake. These results indicate that site-specific soils must be used to screen plants for uranium extraction capability; plant behavior in hydroponic systems does not correlate well with that in soil systems. One plant species, Juniper, exhibited consistent uranium extraction efficiencies and BACs in both sandy and organic soils, suggesting unique uranium extraction capabilities.

  17. Poor Tc-99m dimercaptosuccinic acid uptake, re-evaluation with Tc-99m MAG3 scintigraphy in Lowe syndrome

    PubMed Central

    Koca, Gokhan; Atilgan, Hasan Ikbal; Demirel, Koray; Diri, Akif; Korkmaz, Meliha

    2011-01-01

    Tc-99m dimercaptosuccinic acid (DMSA) is filtered through the glomeruli and reabsorbed by the proximal tubules as low molecular weight proteins. In Lowe syndrome this mechanism is impaired and so poor DMSA uptake is seen. Poor DMSA uptake was shown in very few studies, but none mentioned normal Tc-99m MAG3 uptake. In this case, the patient had poor DMSA uptake, normal MAG3 uptake and a neurogenic bladder in anterior to the left kidney that attenuates left kidney. PMID:23559713

  18. Influence of free fatty acids on glucose uptake in prostate cancer cells☆

    PubMed Central

    Andersen, Kim Francis; Divilov, Vadim; Sevak, Kuntalkumar; Koziorowski, Jacek; Lewis, Jason S.; Pillarsetty, NagaVaraKishore

    2016-01-01

    Introduction The study focuses on the interaction between glucose and free fatty acids (FFA) in malignant human prostate cancer cell lines by an in vitro observation of uptake of fluoro-2-deoxy-d-glucose (FDG) and acetate. Methods Human prostate cancer cell lines (PC3, CWR22Rv1, LNCaP, and DU145) were incubated for 2 h and 24 h in glucose-containing (5.5 mM) Dulbecco’s Modified Eagle’s Medium (DMEM) with varying concentrations of the free fatty acid palmitate (0–1.0 mM). Then the cells were incubated with [18 F]-FDG (1 µCi/mL; 0.037 MBq/mL) in DMEM either in presence or absence of glucose and in presence of varying concentrations of palmitate for 1 h. Standardized procedures regarding cell counting and measuring for 18F radioactivity were applied. Cell uptake studies with 14C-1-acetate under the same conditions were performed on PC3 cells. Results In glucose containing media there was significantly increased FDG uptake after 24 h incubation in all cell lines, except DU145, when upper physiological levels of palmitate were added. A 4-fold increase of FDG uptake in PC3 cells (15.11% vs. 3.94%/106 cells) was observed in media with 1.0 mM palmitate compared to media with no palmitate. The same tendency was observed in PC3 and CWR22Rv1 cells after 2 h incubation. In glucose-free media no significant differences in FDG uptake after 24 h incubation were observed. The significant differences after 2 h incubation all pointed in the direction of increased FDG uptake when palmitate was added. Acetate uptake in PC3 cells was significantly lower when palmitate was added in glucose-free DMEM. No clear tendency when comparing FDG or acetate uptake in the same media at different time points of incubation was observed. Conclusions Our results indicate a FFA dependent metabolic boost/switch of glucose uptake in PCa, with patterns reflecting the true heterogeneity of the disease. PMID:24440212

  19. Fate and Uptake of Pharmaceuticals in Soil–Plant Systems

    PubMed Central

    2014-01-01

    Pharmaceuticals have been detected in the soil environment where there is the potential for uptake into crops. This study explored the fate and uptake of pharmaceuticals (carbamazepine, diclofenac, fluoxetine, propranolol, sulfamethazine) and a personal care product (triclosan) in soil–plant systems using radish (Raphanus sativus) and ryegrass (Lolium perenne). Five of the six chemicals were detected in plant tissue. Carbamazepine was taken up to the greatest extent in both the radish (52 μg/g) and ryegrass (33 μg/g), whereas sulfamethazine uptake was below the limit of quantitation (LOQ) (<0.01 μg/g). In the soil, concentrations of diclofenac and sulfamethazine dropped below the LOQ after 7 days. However, all pharmaceuticals were still detectable in the pore water at the end of the experiment. The results demonstrate the ability of plant species to accumulate pharmaceuticals from soils with uptake apparently specific to both plant species and chemical. Results can be partly explained by the hydrophobicity and extent of ionization of each chemical in the soil. PMID:24405013

  20. Uptake and incorporation of saturated and unsaturated fatty acids into macrophage lipids and their effect upon macrophage adhesion and phagocytosis.

    PubMed Central

    Calder, P C; Bond, J A; Harvey, D J; Gordon, S; Newsholme, E A

    1990-01-01

    Murine thioglycollate-elicited peritoneal macrophages were cultured in the presence of a variety of fatty acids added as complexes with bovine serum albumin. All fatty acids tested were taken up readily by the cells and both neutral and phospholipid fractions were enriched with the fatty acid provided in the medium. This generated a range of cells enriched in saturated, monounsaturated or polyunsaturated fatty acids, including n-3 acids of fish oil origin. Saturated fatty acid enrichment enhanced macrophage adhesion to both tissue culture plastic and bacterial plastic compared with enrichment with polyunsaturated fatty acids. Macrophages enriched with the saturated fatty acids myristate or palmitate showed decreases of 28% and 21% respectively in their ability to phagocytose unopsonized zymosan particles. Those enriched with polyunsaturated fatty acids showed 25-55% enhancement of phagocytic capacity. The greatest rate of uptake was with arachidonate-enriched cells. Phagocytic rate was highly correlated with the saturated/unsaturated fatty acid ratio, percentage of polyunsaturated fatty acid and index of unsaturation, except for macrophages enriched with fish-oil-derived fatty acids; they showed lower phagocytic activity than expected on the basis of their degree of unsaturation. These results suggest that membrane fluidity is important in determining macrophage adhesion and phagocytic activity. However, in the case of phagocytosis, this effect may be partially overcome if the cells are enriched with fish-oil-derived fatty acids. Thus it may be possible to modulate the activity of cells of the immune system, and so an immune response, by dietary lipid manipulation. PMID:2117922

  1. The effect of fatty acid surfactants on the uptake of ozone to aqueous halogenide particles

    NASA Astrophysics Data System (ADS)

    Rouvière, A.; Ammann, M.

    2010-12-01

    The reactive uptake of ozone to deliquesced potassium iodide aerosol particles coated with linear saturated fatty acids (C9, C12, C15, C18 and C20) was studied. The experiments were performed in an aerosol flow tube at 293 K and atmospheric pressure. The uptake coefficient on pure deliquesced KI aerosol was γ = (1.10±0.20)×10-2 at 72-75% relative humidity. In presence of organic coatings, the uptake coefficient decreased significantly for long straight chain surfactants (≥C15), while it was only slightly reduced for the short ones (C9, C12). We linked the kinetic results to the monolayer properties of the surfactants, and specifically to the expected phase state of the monolayer formed (liquid expanded or liquid condensed state). The results showed a decrease of the uptake coefficient by 30% for C12, 85% for C15 and 50% for C18 in presence of a monolayer of a fatty acid at the equilibrium spreading pressure at the air/water interface. The variation among C12, C15 and C18 follows the density of the monolayer at equilibrium spreading pressure, which is highest for the C15 fatty acid. We also investigated the effect of organic films to mixed deliquesced aerosol composed of a variable mixture of KI and NaCl, which allowed determining the resistance exerted to O3 at the aqueous surface by the two longer chained surfactants pentadecanoic acid (C15) and stearic acid (C18). For these, the probability that a molecule hitting the surface is actually transferred to the aqueous phase underneath was βC15=6.8×10-4 and βC18 = 3.3×10-4, respectively. Finally, the effect of two-component coatings, consisting of a mixture of long and short chained surfactants, was studied qualitatively.

  2. Plant uptake and soil retention of phthalic acid applied to Norfolk sandy loam

    SciTech Connect

    Dorney, J.R.; Weber, J.B.; Overcash, M.R.; Strek, H.J.

    1985-01-01

    Plant uptake and soil retention of /sup 14/C carboxyl-labeled phthalic acid were studied at application rates of 0.6, 6.0, 60.0, and 600.0 ppm (soil dry weight) to Norfolk sandy loam (Typic Paleudult, fine loamy, kaolinitic, thermic). Height and dry weight of corn (Zea mays L. Pioneer 3368A) (21 day), tall fescue (Festuca arundinacea Schreb. Kentucky 31) (45 day) immature soybean (Glycine max (L.) Merr. Altoona) (21 day) plant, mature soybean plant, and mature wheat (Triticum aestivum L. Butte) straw were not affected by phthalic acid applied to soil. In addition, soybean seed and wheat seed dry weight were unaffected. Immature wheat (40 day) height decreased at the 600 ppm rate. Plant uptake of phthalic acid ranged from 0 to 23 ppm and was significantly above background for all plants and plant materials except soybean pods. Fescue and immature plants exhibited the highest concentration of phthalic acid while mature wheat plants and wheat seeds exhibited the least. Most of the phthalic acid volatilized or was decomposed from the soil by the end of the study; an average of only 5.7% of the originally applied chemical was recovered in both soil or plants. An average of 0.02% of the originally applied phthalic acid leached out of the treated zone. Considering the low toxicity of phthalic acid and its relatively rapid disappearance from soil, it is unlikely to become a health hazard from contaminated plants. However, plant uptake of other toxic organics could potentially become a hazard on soils treated with sludge containing significant quantities of these substances.

  3. Uptake of formaldehyde by sulfuric acid solutions - Impact on stratospheric ozone

    NASA Technical Reports Server (NTRS)

    Tolbert, Margaret A.; Pfaff, Jeanne; Jayaweera, Indira; Prather, Michael J.

    1993-01-01

    The study investigates the uptake of CH2O by low temperature sulfuric acid solutions representative of global stratospheric particulate. It is argued that if similar uptake occurs under stratospheric pressures of CH2O, i.e., 1000 times lower than used in the present study, then the removal of CH2O from the gas phase can take away a significant source of odd hydrogen in the mid- and high-latitude lower stratosphere. It is shown that with the inclusion of this reaction, concentrations of OH and H2O are reduced by as much as 4 percent under background levels of aerosols and more than 15 percent under elevated (volcanic) conditions. The accumulation of CH2O in stratospheric aerosols over a season, reaching about 1 M solutions, will alter the composition and may even change the reactivity of these sulfuric acid-water mixtures.

  4. Morphological and chemical modification of mineral dust: Observational insight into the heterogeneous uptake of acidic gases

    NASA Astrophysics Data System (ADS)

    Matsuki, Atsushi; Iwasaka, Yasunobu; Shi, Guangyu; Zhang, Daizhou; Trochkine, Dmitri; Yamada, Maromu; Kim, Yoon-Suk; Chen, Bin; Nagatani, Tetsuji; Miyazawa, Takeshi; Nagatani, Masahiro; Nakata, Hiroshi

    2005-11-01

    Aerosol samples were collected in the urban atmosphere of Beijing, China, by deploying a tethered balloon. Coarse particles (d > 1 μm) were individually analyzed using electron microscopes, to investigate the extent of dust modification by acidic gases in the atmosphere. Based on the elemental composition, irregularly shaped mineral dust was separated into carbonate and silicate groups. Both sulfate and nitrate were found to accumulate on carbonate more readily than silicate particles. Interestingly, spherical particles resembling Ca-carbonate in composition were spotted frequently in the samples. These Ca-rich spherical particles were more abundant under humid conditions, suggesting that they are deliquesced carbonate particles that formed in the atmosphere following the uptake of acidic gases. Sulfate and nitrate were more frequently detected in the Ca-rich spherical particles than in carbonate in the original solid form, indicating that the gas uptake efficiency of carbonate is further enhanced after the phase transition.

  5. In vitro inhibition of OATP-mediated uptake of phalloidin using bile acid derivatives

    SciTech Connect

    Herraez, Elisa; Macias, Rocio I.R.; Vazquez-Tato, Jose; Vicens, Marta; Monte, Maria J.; Marin, Jose J.G.

    2009-08-15

    Hepatocyte uptake of phalloidin is carried out mainly by OATP1B1. We have used this compound as a prototypic substrate and assayed the ability to inhibit OATP-mediated phalloidin transport of four bile acid derivatives (BALU-1, BALU-2, BALU-3 and BALU-4) that showed positive results in preliminary screening. Using Xenopus laevis oocytes for heterologous expression of transporters, BALUs were found to inhibit taurocholic acid (TCA) transport by OATP1B1 (but not OATP1B3) as well as by rat Oatp1a1, Oatp1a4 and Oatp1b2. The study of their ability to inhibit sodium-dependent bile acid transporters revealed that the four BALUs induced an inhibition of rat Asbt-mediated TCA transport, which was similar to TCA-induced self-inhibition. Regarding human NTCP and rat Ntcp, BALU-1 differs from the other three BALUS in its lack of effect on TCA transport by these proteins. Using HPLC-MS/MS and CHO cells stably expressing OATP1B1 the ability of BALU-1 to inhibit the uptake of phalloidin itself by this transporter was confirmed. Kinetic analysis using X. laevis oocytes revealed that BALU-1-induced inhibition of OATP1B1 was mainly due to a competitive mechanism (Ki = 8 {mu}M). In conclusion, BALU-1 may be useful as a pharmacological tool to inhibit the uptake of compounds mainly taken up by OATP1B1 presumably without impairing bile acid uptake by the major carrier accounting for this process, i.e., NTCP.

  6. The effect of fatty acid surfactants on the uptake of ozone to aqueous halogenide particles

    NASA Astrophysics Data System (ADS)

    Rouvière, A.; Ammann, M.

    2010-06-01

    The reactive uptake of ozone to deliquesced potassium iodide aerosol particles coated with linear saturated fatty acids (C9, C12, C15, C18 and C20) as surfactants was studied. The experiments were performed in an aerosol flow tube at 293 K and atmospheric pressure. The uptake coefficient on pure deliquesced KI aerosol was γ=(1.10±0.20)×10-2 at 72-75% relative humidity. In presence of organic coatings, the uptake coefficient decreased significantly for long straight chain surfactants (>C15), while it was only slightly reduced for the short ones (C9, C12). We linked the kinetic results to the monolayer properties of the surfactants, and specifically to the phase state of the monolayer formed (liquid expanded or liquid condensed state). We also investigated the effect of organic films to mixed deliquesced aerosol composed of a variable mixture of KI and NaCl, which allowed determining the resistance exerted to O3 at the aqueous surface by the two longer chained surfactants pentadecanoic acid (C15) and stearic acid (C18). Finally, the effect of two-component coatings, consisting of a mixture of long and short chained surfactants, was also studied.

  7. Fasting-induced liver GADD45β restrains hepatic fatty acid uptake and improves metabolic health.

    PubMed

    Fuhrmeister, Jessica; Zota, Annika; Sijmonsma, Tjeerd P; Seibert, Oksana; Cıngır, Şahika; Schmidt, Kathrin; Vallon, Nicola; de Guia, Roldan M; Niopek, Katharina; Berriel Diaz, Mauricio; Maida, Adriano; Blüher, Matthias; Okun, Jürgen G; Herzig, Stephan; Rose, Adam J

    2016-01-01

    Recent studies have demonstrated that repeated short-term nutrient withdrawal (i.e. fasting) has pleiotropic actions to promote organismal health and longevity. Despite this, the molecular physiological mechanisms by which fasting is protective against metabolic disease are largely unknown. Here, we show that, metabolic control, particularly systemic and liver lipid metabolism, is aberrantly regulated in the fasted state in mouse models of metabolic dysfunction. Liver transcript assays between lean/healthy and obese/diabetic mice in fasted and fed states uncovered "growth arrest and DNA damage-inducible" GADD45β as a dysregulated gene transcript during fasting in several models of metabolic dysfunction including ageing, obesity/pre-diabetes and type 2 diabetes, in both mice and humans. Using whole-body knockout mice as well as liver/hepatocyte-specific gain- and loss-of-function strategies, we revealed a role for liver GADD45β in the coordination of liver fatty acid uptake, through cytoplasmic retention of FABP1, ultimately impacting obesity-driven hyperglycaemia. In summary, fasting stress-induced GADD45β represents a liver-specific molecular event promoting adaptive metabolic function. PMID:27137487

  8. The effects of anaesthetics on the uptake and release of amino acid neurotransmitters in thalamic slices.

    PubMed Central

    Kendall, T. J.; Minchin, M. C.

    1982-01-01

    1 The effect of thiopentone, methohexitone, urethane and ketamine on the uptake and release of gamma-aminobutyric acid (GABA) and D-aspartate by rat thalamic slices has been investigated. 2 A high, supra-anaesthetic concentration of methohexitone increased the uptake of both D-aspartate and GABA. 3 None of the anaesthetics used had any detectable effect upon the spontaneous release of either amino acid. 4 Urethane and ketamine had no effect upon the K+-stimulated release of either amino acid. 5 Methohexitone and thiopentone produced a biphasic dose-response on the K+-stimulated release of both amino acids; low concentrations enhanced release, high concentrations depressed release. 6 Bicuculline hydrochloride and picrotoxin both significantly reduced the barbiturate-induced enhancement of K+-stimulated amino acid release, but did not significantly alter the depression of K+-stimulated release at higher barbiturate concentrations. 7 Baclofen, either alone (1 microM to 1 mM), or tested against the barbiturates, had no detectable effect. PMID:6122480

  9. Correlation between organic acid exudation and metal uptake by ectomycorrhizal fungi grown on pond ash in vitro.

    PubMed

    Ray, Prasun; Adholeya, Alok

    2009-04-01

    Experiments were conducted to investigate the effect of coal ash on organic acid exudation and subsequent metal uptake by ectomycorrhizal fungi. Four isolates of ectomycorrhizal fungi namely, Pisolithus tinctorius (EM-1293 and EM-1299), Scleroderma verucosum (EM-1283) and Scleroderma cepa (EM-1233) were grown on pond ash moistened with Modified Melin-Norkans medium in vitro. Exudation of formic acid, malic acid and succinic acid by these fungi were detected by HPLC. Mycelial accumulation of Al, As, Cd, Cr, Ni and Pb by these fungi was assayed by atomic absorption spectrophotometer. Relationship between organic acid exudation and metal uptake was determined using classical multivariate linear regression model. Correlation between organic acid exudation and metal uptake could be substantiated when several metals are considered collectively. The finding supports the widespread role of low molecular weight organic acid as a function of tolerance, when exposed to metals in vitro. PMID:18800194

  10. The uptake of N{sub 2}O{sub 5} onto small sulfuric acid particles

    SciTech Connect

    Hanson, D.R.; Lovejoy, E.R. |

    1994-11-01

    The probabilities for N{sub 2}O{sub 5} loss onto sulfuric acid aerosol (60-80 wt% H{sub 2}SO{sub 4}, 0.1-0.2 {mu}m radius, 230-300 K) were measured using a laminar flow reactor coupled to a sulfuric acid aerosol source and a chemical ionization mass spectrometer. The aerosol morphology was extracted from measurements of the aerosol extinction of ultraviolet light (200-370nm) by using Mie theory. The reaction probabilities, {gamma}, are large (0.06-0.12) and are comparable to probabilities measured previously under similar conditions on bulk sulfuric acid surfaces and small aerosol. These measurements confirm that the overall reaction of N{sub 2}O{sub 5} with H{sub 2}O in/on 60-80% sulfuric acid is fast and the uptake is due to loss very close to the liquid surface. 15 refs., 3 figs., 1 tab.

  11. Receptor-mediated uptake of low density lipoprotein stimulates bile acid synthesis by cultured rat hepatocytes

    SciTech Connect

    Junker, L.H.; Davis, R.A. )

    1989-12-01

    The cellular mechanisms responsible for the lipoprotein-mediated stimulation of bile acid synthesis in cultured rat hepatocytes were investigated. Adding 280 micrograms/ml of cholesterol in the form of human or rat low density lipoprotein (LDL) to the culture medium increased bile acid synthesis by 1.8- and 1.6-fold, respectively. As a result of the uptake of LDL, the synthesis of (14C)cholesterol from (2-14C)acetate was decreased and cellular cholesteryl ester mass was increased. Further studies demonstrated that rat apoE-free LDL and apoE-rich high density lipoprotein (HDL) both stimulated bile acid synthesis 1.5-fold, as well as inhibited the formation of (14C)cholesterol from (2-14C)acetate. Reductive methylation of LDL blocked the inhibition of cholesterol synthesis, as well as the stimulation of bile acid synthesis, suggesting that these processes require receptor-mediated uptake. To identify the receptors responsible, competitive binding studies using 125I-labeled apoE-free LDL and 125I-labeled apoE-rich HDL were performed. Both apoE-free LDL and apoE-rich HDL displayed an equal ability to compete for binding of the other, suggesting that a receptor or a group of receptors that recognizes both apolipoproteins is involved. Additional studies show that hepatocytes from cholestyramine-treated rats displayed 2.2- and 3.4-fold increases in the binding of apoE-free LDL and apoE-rich HDL, respectively. These data show for the first time that receptor-mediated uptake of LDL by the liver is intimately linked to processes activating bile acid synthesis.

  12. Ruminant and industrial trans-fatty acid uptake in the heart.

    PubMed

    Ganguly, Riya; LaVallee, Renee; Maddaford, Thane G; Devaney, Brittany; Bassett, Chantal M C; Edel, Andrea L; Pierce, Grant N

    2016-05-01

    Dietary trans-fats are strongly associated with heart disease. However, the capacity for the tissues of the body, and specifically the heart, to take up trans-fats is unknown. It is also unknown if different trans-fats have different uptake capacities in the heart and other tissues of the body. Diets of low-density lipoprotein receptor-deficient mice were supplemented for 14weeks with foods that contained 1.5% of the trans-fat elaidic acid or vaccenic acid. Tissues were extracted and frozen in liquid nitrogen, and then lipids were analyzed by gas chromatography for fatty acid content. Isolated cardiomyocytes were also exposed to elaidic or vaccenic acid in cell culture media for 24h. Dietary supplementation with vaccenic or elaidic acid resulted in a 20-fold higher accumulation of these TFAs in fat deposits in the body in comparison to liver. Liver tissue accumulated about twice as much per gram tissue as heart. Similar quantities of both elaidic acid and vaccenic acid were taken up by the tissues. Isolated cardiomyocytes exhibited an unusually large uptake of trans-fat, and this was dependent upon both the concentration and duration of exposure to the trans-fats but not upon the type of trans-fat. Expression levels of CD36 and FATP4 were not significantly changed during dietary interventions or exposure of cells to trans-fats. We conclude that fat, liver and heart (including cardiomyocytes) are all capable of accumulating trans-fat in response to dietary supplementation without changes in fatty acid transport protein expression. PMID:27133424

  13. Dietary uptake of omega-3 fatty acids in mouse tissue studied by time-of-flight secondary ion mass spectrometry (TOF-SIMS).

    PubMed

    Sjövall, Peter; Rossmeisl, Martin; Hanrieder, Jörg; Kuda, Ondrej; Kopecky, Jan; Bryhn, Morten

    2015-07-01

    Dietary intake of omega-3 fatty acids is associated with considerable health benefits, including the prevention of metabolic disorders such as cardiovascular disease and type 2 diabetes. Furthermore, incorporation of the main omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), at the systemic level has been found to be more efficient when these fatty acids are supplied in the form of marine phospholipids compared to triglycerides. In this work, the uptake of omega-3 fatty acids and their incorporation in specific lipids were studied in adipose, skeletal muscle, and liver tissues of mice given high-fat diets with or without omega-3 supplements in the form of phospholipids or triglycerides using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The results demonstrate significant uptake of EPA and DHA, and the incorporation of these fatty acids in specific lipid molecules, in all three tissue types in response to the dietary omega-3 supplements. Moreover, the results indicate reduced concentrations of arachidonic acid (AA) and depletion of lipids containing AA in tissue samples from mice given supplementary omega-3, as compared to the control mice. The effect on the lipid composition, in particular the DHA uptake and AA depletion, was found to be significantly stronger when the omega-3 supplement was supplied in the form of phospholipids, as compared to triglycerides. TOF-SIMS was found to be a useful technique for screening the lipid composition and simultaneously obtaining the spatial distributions of various lipid classes on tissue surfaces. PMID:25694146

  14. Synthesis and cellular uptake of folic acid-conjugated cellulose nanocrystals for cancer targeting.

    PubMed

    Dong, Shuping; Cho, Hyung Joon; Lee, Yong Woo; Roman, Maren

    2014-05-12

    Elongated nanoparticles have recently been shown to have distinct advantages over spherical ones in targeted drug delivery applications. In addition to their oblong geometry, their lack of cytotoxicity and numerous surface hydroxyl groups make cellulose nanocrystals (CNCs) promising drug delivery vectors. Herein we report the synthesis of folic acid-conjugated CNCs for the targeted delivery of chemotherapeutic agents to folate receptor-positive cancer cells. Folate receptor-mediated cellular binding/uptake of the conjugate was demonstrated on human (DBTRG-05MG, H4) and rat (C6) brain tumor cells. Folate receptor expression of the cells was verified by immunofluorescence staining. Cellular binding/uptake of the conjugate by DBTRG-05MG, H4, and C6 cells was 1452, 975, and 46 times higher, respectively, than that of nontargeted CNCs. The uptake mechanism was determined by preincubation of the cells with the uptake inhibitors chlorpromazine or genistein. DBTRG-05MG and C6 cells internalized the conjugate primarily via caveolae-mediated endocytosis, whereas H4 cells internalized the conjugate primarily via clathrin-mediated endocytosis. PMID:24716601

  15. Dehydroascorbic acid uptake by coronary artery smooth muscle: effect of intracellular acidification.

    PubMed Central

    Holmes, Melanie E; Mwanjewe, James; Samson, Sue E; Haist, James V; Wilson, John X; Dixon, S Jeffrey; Karmazyn, Morris; Grover, Ashok K

    2002-01-01

    Dehydroascorbic acid (DHAA) enters cells via Na(+)-independent glucose transporters (GLUT) and is converted to ascorbate. However, we found that Na(+) removal inhibited [(14)C]DHAA uptake by smooth-muscle cells cultured from pig coronary artery. The uptake was examined for 2-12 min at 10-200 microM DHAA in either the presence of 134 mM Na(+) or in its absence (N-methyl D-glucamine, choline or sucrose replaced Na(+)). This inhibition of DHAA uptake by Na(+) removal was paradoxical because it was inhibited by 2-deoxyglucose and cytochalasin B, as expected of transport via the GLUT pathway. We tested the hypothesis that this paradox resulted from an inefficient intracellular reduction of [(14)C]DHAA into [(14)C]ascorbate upon intracellular acidosis caused by the Na(+) removal. Consistent with this hypothesis: (i) the Na(+)/H(+)-exchange inhibitors ethylisopropyl amiloride and cariporide also decreased the uptake, (ii) Na(+) removal and Na(+)/H(+)-exchange inhibitors lowered cytosolic pH, with the decrease being larger in 12 min than in 2 min, and (iii) less of the cellular (14)C was present as ascorbate (determined by HPLC) in cells in Na(+)-free buffer than in those in Na(+)-containing buffer. This inability to obtain ascorbate from extracellular DHAA may be detrimental to the coronary artery under hypoxia-induced acidosis during ischaemia/reperfusion. PMID:11853561

  16. Optimising root system hydraulic architectures for water uptake

    NASA Astrophysics Data System (ADS)

    Meunier, Félicien; Couvreur, Valentin; Draye, Xavier; Javaux, Mathieu

    2015-04-01

    In this study we started from local hydraulic analysis of idealized root systems to develop a mathematical framework necessary for the understanding of global root systems behaviors. The underlying assumption of this study was that the plant is naturally optimised for the water uptake. The root system is thus a pipe network dedicated to the capture and transport of water. The main objective of the present research is to explain the fitness of major types of root architectures to their environment. In a first step, we developed links between local hydraulic properties and macroscopic parameters of (un)branched roots. The outcome of such an approach were functions of apparent conductance of entire root system and uptake distribution along the roots. We compared our development with some allometric scaling laws for the root water uptake: under the same simplifying assumptions we were able to obtain the same results and even to expand them to more physiological cases. Using empirical data of measured root conductance, we were also able to fit extremely well the data-set with this model. In a second stage we used generic architecture parameters and an existent root growth model to generate various types of root systems (from fibrous to tap). We combined both sides (hydraulic and architecture) then to maximize under a volume constraint either apparent conductance of root systems or the soil volume explored by active roots during the plant growth period. This approach has led to the sensitive parameters of the macroscopic parameters (conductance and location of the water uptake) of each single plant selected for this study. Scientific questions such as: "What is the optimal sowing density of a given hydraulic architecture ?" or "Which plant traits can we change to better explore the soil domain ?" can be also addressed with this approach: some potential applications are illustrated. The next (and ultimate phase) will be to validate our conclusions with real architectures

  17. Inhibition of Large Neutral Amino Acid Transporters Suppresses Kynurenic Acid Production Via Inhibition of Kynurenine Uptake in Rodent Brain.

    PubMed

    Sekine, Airi; Kuroki, Yusuke; Urata, Tomomi; Mori, Noriyuki; Fukuwatari, Tsutomu

    2016-09-01

    The tryptophan metabolite, kynurenic acid (KYNA), is a preferential antagonist of the α7 nicotinic acetylcholine receptor and N-methyl-D-aspartic acid receptor at endogenous brain concentrations. Recent studies have suggested that increases of brain KYNA levels are involved in psychiatric disorders such as schizophrenia and depression, and regulation of KYNA production has become a new target for treatment of these diseases. Kynurenine (KYN), the immediate precursor of KYNA, is transported into astrocytes via large neutral amino acid transporters (LATs). In the present study, the effect of LATs regulation on KYN uptake and KYNA production was investigated in vitro and in vivo using an LATs inhibitor, 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH). In the in vitro study, cortical slices of rat brain were incubated with a physiological concentration of KYN and 3 µmol/L-3 mmol/L BCH. BCH inhibited KYNA production and KYN uptake in a dose-dependent manner, and their IC50 values were 90.7 and 97.4 µmol/L, respectively. In the in vivo study, mice were administered KYN (50 mg/kg BW) orally and BCH (200 mg/kg BW) intravenously. Administration of KYN increased brain KYN and KYNA levels compared with the mice treated with vehicle, whereas additional administration of BCH suppressed KYN-induced elevations in KYN and KYNA levels to 50 and 70 % in the brain. These results suggest that inhibition of LATs prevented the increase of KYNA production via blockade of KYN uptake in the brain in vitro and in vivo. LATs can be a target to modulate brain function by regulation of KYNA production in the brain. PMID:27161376

  18. Hepatic fatty acid uptake is regulated by the sphingolipid acyl chain length.

    PubMed

    Park, Woo-Jae; Park, Joo-Won; Merrill, Alfred H; Storch, Judith; Pewzner-Jung, Yael; Futerman, Anthony H

    2014-12-01

    Ceramide synthase 2 (CerS2) null mice cannot synthesize very-long acyl chain (C22-C24) ceramides resulting in significant alterations in the acyl chain composition of sphingolipids. We now demonstrate that hepatic triacylglycerol (TG) levels are reduced in the liver but not in the adipose tissue or skeletal muscle of the CerS2 null mouse, both before and after feeding with a high fat diet (HFD), where no weight gain was observed and large hepatic nodules appeared. Uptake of both BODIPY-palmitate and [VH]-palmitate was also abrogated in the hepa- tocytes and liver. The role of a number of key proteins involved in fatty acid uptake was examined, including FATP5, CD36/FAT, FABPpm and cytoplasmic FABP1. Levels of FATP5 and FABP1 were decreased in the CerS2 null mouse liver, whereas CD36/FAT levels were significantly elevated and CD36/FAT was also mislocalized upon insulin treatment. Moreover, treatment of hepatocytes with C22-C24-ceramides down-regulated CD36/FAT levels. Infection of CerS2 null mice with recombinant adeno-associated virus (rAAV)-CerS2 restored normal TG levels and corrected the mislocalization of CD36/FAT, but had no effect on the intracellular localization or levels of FATP5 or FABP1. Together, these results demonstrate that hepatic fatty acid uptake via CD36/FAT can be regulated by altering the acyl chain composition of sphingolipids. PMID:25241943

  19. The Campylobacter jejuni Ferric Uptake Regulator Promotes Acid Survival and Cross-Protection against Oxidative Stress.

    PubMed

    Askoura, Momen; Sarvan, Sabina; Couture, Jean-François; Stintzi, Alain

    2016-05-01

    Campylobacter jejuni is a prevalent cause of bacterial gastroenteritis in humans worldwide. The mechanisms by which C. jejuni survives stomach acidity remain undefined. In the present study, we demonstrated that the C. jejuni ferric uptake regulator (Fur) plays an important role in C. jejuni acid survival and acid-induced cross-protection against oxidative stress. A C. jejuni Δfur mutant was more sensitive to acid than the wild-type strain. Profiling of the acid stimulon of the C. jejuni Δfur mutant allowed us to uncover Fur-regulated genes under acidic conditions. In particular, Fur was found to upregulate genes involved in flagellar and cell envelope biogenesis upon acid stress, and mutants with deletions of these genes were found to be defective in surviving acid stress. Interestingly, prior acid exposure of C. jejuni cross-protected against oxidative stress in a catalase (KatA)- and Fur-dependent manner. Western blotting and reverse transcription-quantitative PCR revealed increased expression of KatA upon acid stress. Electrophoretic mobility shift assays (EMSAs) demonstrated that the binding affinity between Fur and the katA promoter is reduced in vitro under conditions of low pH, rationalizing the higher levels of expression of katA under acidic conditions. Strikingly, the Δfur mutant exhibited reduced virulence in both human epithelial cells and the Galleria mellonella infection model. Altogether, this is the first study showing that, in addition to its role in iron metabolism, Fur is an important regulator of C. jejuni acid responses and this function cross-protects against oxidative stress. Moreover, our results clearly demonstrate Fur's important role in C. jejuni pathogenesis. PMID:26883589

  20. Purification of organic acids by chromatography with strong anionic resins: Investigation of uptake mechanisms.

    PubMed

    Lemaire, Julien; Blanc, Claire-Line; Lutin, Florence; Théoleyre, Marc-André; Stambouli, Moncef; Pareau, Dominique

    2016-08-01

    Bio-based organic acids are promising renewable carbon sources for the chemical industry. However energy-consuming purification processes are used, like distillation or crystallization, to reach high purities required in some applications. That is why preparative chromatography was studied as an alternative separation technique. In a previous work dealing with the purification of lactic, succinic and citric acids, the Langmuir model was insufficient to explain the elution profiles obtained with a strong anionic resin. Consequently the Langmuir model was coupled with a usual ion-exchange model to take into account the retention of their conjugate bases (<2%), which are commonly neglected at low pH (<1.5). Elution simulations with both uptake mechanisms fitted very well with experimental pulse tests. Only two parameters were optimized (equilibrium constant of acid uptake and ion-exchange selectivity coefficient of conjugate base) and their value were coherent with experimental and resin suppliers' data. These results confirmed that the singular tailing and apparent delay observed with succinic and citric acids can be explained by the high affinity of succinate and citrate for resin cationic sites. The model was implemented in a preparative chromatography simulation program in order to optimize operating parameters of our pilot-scale ISMB unit (Improved Simulated Moving Bed). The comparison with experimental ISMB profiles was conclusive. PMID:27373374

  1. Contrast of volatile fatty acid driven and inorganic acid or base driven phosphorus release and uptake in enhanced biological phosphorus removal.

    PubMed

    Randall, Andrew A

    2012-04-01

    Addition of an inorganic acid or base was detrimental to net phosphorus removals in short-term batch experiments, suggesting there might be system upset when pH changes. In contrast, addition of volatile fatty acids (VFAs) increased anaerobic phosphorus release and aerobic phosphorus uptake while maintaining or improving net phosphorus removals. The effect of pH change differed if the acid or base added was inorganic versus organic. Volatile fatty acids that resulted in poly-3-hydroxy-butyrate rather than poly-3-hydroxy-valerate resulted in greater net phosphorus removals, and this corresponded to differences in consumption of reducing equivalents. Acetic acid resulted in improved net phosphorus removal compared to sodium acetate, suggesting that acid forms of VFAs might be superior as supplemental VFAs. It is hypothesized that anaerobic phosphorus release following addition of inorganic acid is primarily a result of phosphorus and proton (H+) symport (excretion from the cell) for pH homeostasis, whereas addition of VFAs results in phosphorus and H+ release to maintain the proton motive force. PMID:22834218

  2. Development of a high-affinity GABA uptake system in embryonic amphibian spinal neurons.

    PubMed

    Lamborghini, J E; Iles, A

    1985-11-01

    High-affinity uptake systems for amino acid neurotransmitter precursors have been highly correlated with the use of the particular amino acid or its derivative as a transmitter. We have found interneurons in the Xenopus embryo spinal cord which accumulate GABA by a high-affinity uptake system. They originate near the end of gastrulation and their ability to accumulate GABA first appears at the early tail bud stage. By position and appearance they are comparable to some of the embryonic interneurons described by A. Roberts and J. D. W. Clarke (1982, Phil. Trans. R. Soc. London Ser. B 296, 195-212). GABA-accumulating neurons also develop in dissociated cell cultures made from the presumptive spinal cord of neural plate stage Xenopus embryos. GABA accumulation in cultured neurons, as in cells in vivo, occurs via a high-affinity uptake system; GABA-accumulating cells have the same time of origin as the cells in vivo, and the ability to accumulate GABA in the population of cultured neurons appears at a time equivalent to that observed in intact sibling embryos. Thus it seems likely that the population of GABA-accumulating neurons developing in cell culture corresponds to the GABA-accumulating interneurons in vivo. The development of these neurons in dissociated cell cultures permits perturbation experiments that would be difficult to perform in vivo. We have examined the development of high-affinity GABA uptake in conditions that permit no electrical impulse activity in the cultures. The onset and extent of development of GABA accumulation in the neuronal population are normal under these conditions. PMID:3932109

  3. Effects of gamma-aminobutyric acid on skate retinal horizontal cells: evidence for an electrogenic uptake mechanism.

    PubMed Central

    Malchow, R P; Ripps, H

    1990-01-01

    In the retinae of many vertebrates, there are classes of horizontal cell that probably utilize gamma-aminobutyric acid (GABA) as a neurotransmitter. As with other amino acid transmitter agents, the postsynaptic action of GABA is thought to be terminated by uptake into neurons and glia surrounding the release site. The present study examined whether an uptake system for GABA could be detected in isolated skate horizontal cells by means of electrophysiological methods. Pressure ejection of GABA onto voltage-clamped horizontal cells produced an inward current that showed no sign of desensitization regardless of the GABA concentration. The dose-response relationship followed simple Michaelis-Menten kinetics, with a half-maximal response elicited at approximately 110 microM. Nipecotic acid produced a similar current and reduced the responses to GABA when introduced in the bath solution prior to the GABA pulse. On the other hand, application of 500 microM muscimol or 1 mM baclofen, GABAA and GABAB receptor agonists, respectively, were completely without effect. The GABA-induced current was not blocked by superfusion with 500 microM bicuculline, 500 microM picrotoxin, or 500 microM phaclofen. However, the responses to GABA were abolished when the cells were superfused in Ringer's solution in which choline or lithium had been substituted for sodium, and were reduced when the extracellular chloride concentration was decreased from 266 mM to 16 mM. Current-voltage data showed a maximal response to GABA when the cells were held at or below their resting potential. At more depolarized levels, the inward current became progressively smaller until, near +50 mV, it could no longer be detected; over the range tested (-90 to +50 mV), the response never reversed into an outward current. These findings suggest that the GABA-induced currents in skate horizontal cells are mediated by an electrogenic uptake mechanism. PMID:2247470

  4. Assessment of plant-driven uptake and translocation of clofibric acid by Scirpus validus.

    PubMed

    Zhang, Dong Qing; Gersberg, Richard M; Hua, Tao; Zhu, Junfei; Ng, Wun Jern; Tan, Soon Keat

    2013-07-01

    Pharmaceutical compounds are now considered as emerging contaminants of environmental concern. The overall objective of this study was to evaluate the uptake and translocation of clofibric acid (CA) by the macrophyte Scirpus validus growing hydroponically. A set of the three replicates was established for each exposure time and for each CA concentration. Plants were grown in 4 L vessels (four plants per vessel corresponding to the three exposure period studies, i.e., 7, 14, 18, and 21 days) which contained an aerated modified Hoagland nutrient solution that was spiked with CA at concentrations of 0.5, 1.0, and 2.0 mg L(-1). At each exposure period, CA concentration was measured in the nutrient solutions. A sea sand disruption method was employed for the extraction of CA from plant tissues. The determination of the pharmaceutical concentration was carried out using solid phase extraction (SPE) followed by chromatographic analysis. The quantification of CA concentrations in both nutrient solutions (after SPE) and plant tissues (after extraction) was conducted by chromatographic analysis. CA concentrations of 5.4-26.8 μg g(-1) (fresh weight) were detected in the roots and 7.2-34.6 μg g(-1) (fresh weight) in the shoots after 21 days. Mass balance calculations showed that S. validus uptake alone accounted for a significant contribution (6-13% for the roots and 22-49% for the shoots) of the total loss of CA. The bioaccumulation factors (BAFs) based on fresh weight for the roots ranged from 6.6 to 23.2, while values for the shoots ranged from 9.5 to 32.1. All the BAFs for the shoots were greater than those in the roots, implying that CA has greater tendency to be translocated to the shoots, rather than the roots of S. validus. All the shoot-to-root concentration ratios were more than 1, denoting that the shoots of S. validus do preferentially accumulate CA. We demonstrated that CA can be actively taken up, subsequently translocated and accumulated by aboveground

  5. Uranyl ion uptake capacity of poly (N-isopropylacrylamide/maleic acid) copolymeric hydrogels prepared by gamma rays

    NASA Astrophysics Data System (ADS)

    Kam, Erol; Taşdelen, Betul; Osmanlioglu, A. Erdal

    2012-06-01

    The effect of gel composition, absorbed dose and pH of the solution on the uranyl ion uptake capacity of N-isopropylacrylamide/maleic acid copolymeric hydrogels containing 0-3 mol% of maleic acid at 48 kGy have been investigated. Uranyl uptake capacity of hydrogels are found to increase from 18.5 to 94.8 mg [UO22+]/g dry gel as the mole % of maleic acid content in the gel structure increased from 0 to 3. The percent swelling, equilibrium swelling and diffusion coefficient values have been evaluated for poly(N-isopropylacrylamide/maleic acid) hydrogels at 500 ppm of uranyl nitrate solution.

  6. Effect of HEPES buffer on the uptake and transport of P-glycoprotein substrates and large neutral amino acids

    PubMed Central

    Luo, Shuanghui; Pal, Dhananjay; Shah, Sujay J.; Kwatra, Deep; Paturi, Kalyani D.; Mitra, Ashim. K.

    2010-01-01

    HEPES has been widely employed as an organic buffer agent in cell culture medium as well as uptake and transport experiments in vitro. However, concentrations of HEPES used in such studies vary from one laboratory to another. In this study, we investigated the effect of HEPES on the uptake and bidirectional transport of P-gp substrates employing both Caco-2 and MDCK-MDR1 cells. ATP-dependent uptake of glutamic acid was also examined. ATP production was further quantified applying ATP Determination Kit. An addition of HEPES to the cellular washing and incubation media significantly altered the uptake and transport of P-gp substrates in both Caco-2 and MDCK-MDR1 cells. Uptake of P-gp substrates substantially diminished as the HEPES concentration was raised to 25 mM. Bidirectional (A-B and B-A) transport studies revealed that permeability ratio of PappB-A to PappA-B in the presence of 25 mM HEPES was significantly higher than control. The uptake of phenylalanine is an ATP-independent process, whereas the accumulation of glutamic acid is ATP-dependent. While phenylalanine uptake remained unchanged glutamic acid uptake was elevated with the addition of HEPES. Verapamil is an inhibitor of P-gp mediated uptake, elevation of cyclosporine uptake in the presence of 5 μM verapamil was compromised by the presence of 25 mM HEPES. The results of ATP assay indicated that HEPES stimulated the production of ATP. This study suggests that the addition of HEPES in the medium modulated the energy dependent efflux and uptake processes. The effect of HEPES on P-gp mediated drug efflux and transport may provide some mechanistic insight into possible reasons for inconsistencies in the results reported from various laboratories. PMID:20163160

  7. Proton-dependent glutamine uptake by aphid bacteriocyte amino acid transporter ApGLNT1.

    PubMed

    Price, Daniel R G; Wilson, Alex C C; Luetje, Charles W

    2015-10-01

    Aphids house large populations of the gammaproteobacterial symbiont Buchnera aphidicola in specialized bacteriocyte cells. The combined biosynthetic capability of the holobiont (Acyrthosiphon pisum and Buchnera) is sufficient for biosynthesis of all twenty protein coding amino acids, including amino acids that animals alone cannot synthesize; and that are present at low concentrations in A. pisum's plant phloem sap diet. Collaborative holobiont amino acid biosynthesis depends on glutamine import into bacteriocytes, which serves as a nitrogen-rich amino donor for biosynthesis of other amino acids. Recently, we characterized A. pisum glutamine transporter 1 (ApGLNT1), a member of the amino acid/auxin permease family, as the dominant bacteriocyte plasma membrane glutamine transporter. Here we show ApGLNT1 to be structurally and functionally related to mammalian proton-dependent amino acid transporters (PATs 1-4). Using functional expression in Xenopus laevis oocytes, combined with two-electrode voltage clamp electrophysiology we demonstrate that ApGLNT1 is electrogenic and that glutamine induces large inward currents. ApGLNT1 glutamine induced currents are dependent on external glutamine concentration, proton (H+) gradient across the membrane, and membrane potential. Based on these transport properties, ApGLNT1-mediated glutamine uptake into A. pisum bacteriocytes can be regulated by changes in either proton gradients across the plasma membrane or membrane potential. PMID:26028424

  8. Uptake of intact zinc-ethylenediaminetetraacetic acid from soil is dependent on plant species and complex concentration.

    PubMed

    Collins, Richard N; Merrington, Graham; McLaughlin, Mike J; Knudsen, Chris

    2002-09-01

    Pot experiments were conducted with barley (Hordeum vulgare L.), potato (Solanum tuberosum L.), Indian mustard (Brassicajuncea L.), and white lupin (Lupinus albus L.) to determine the nature of Zn mobilization, uptake, and root-shoot transport from a Zn-contaminated soil in the presence of increasing concentrations of ethylenediaminetetraacetic acid (EDTA; 0.0-3.4 mmole/kg soil). Increasing EDTA concentrations lead to a greater proportion of soil-solution Zn being detected as the ZnEDTA complex. However, a significant increase in the concentration of soil-solution Zn was only observed after the addition of 3.4 mmole EDTA/ kg soil. At this application rate, regardless of the plant species, 97 +/- 9% (+/- SD) of the increase in soil-solution Zn could be accounted for by chelation/desorption, and 89 +/- 9% of total Zn in solution was measured as ZnEDTA. Although the complex was detected in the xylem exudate of B. juncea after 0.34 mmole EDTA/kg soil had been added, ZnEDTA was only found in the xylem exudate of the other plant species following the highest application rate of EDTA. In this case, the accumulation of Zn and the concentration of ZnEDTA in the xylem sap of B. juncea were significantly greater than those of H. vulgare and S. tuberosum. Measurements of plant transpiration following the addition of EDTA indicated that B. juncea experienced greater physiological stress in the presence of high concentrations of EDTA. It was therefore concluded that two different mechanisms of ZnEDTA uptake existed for these plant species. Based on a review of the literature, it was hypothesized that uptake of ZnEDTA by B. juncea occurred only after physiological damage to its root system, whereas uptake by H. vulgare and S. tuberosum was via an apoplastic pathway (passive extracellular transport into the xylem). PMID:12206435

  9. Effect of surface and membrane potentials on IAA (indoleactic acid) uptake and binding by zucchini membrane vesicles

    SciTech Connect

    Clark, K.A.; Goldsmith, M.H.M.

    1986-08-01

    The polar transport of the endogenous hormone controlling extension growth of plant cells, indoleacetic acid (IAA), is thought to depend on transmembrane pH and electrical gradients resulting in part from the action of proton ATPases in the plasma membrane. Elements of this transport process are permeation of the membrane by the undissociated lipophilic indoleacetic acid (IAAH) from the acidic apoplast, followed by dissociation of the weak acid and accumulation of the IAA anion (IAA/sup -/) in the alkaline cytoplasm; a saturable symport of IAA/sup -/ with one or more protons; a carrier-mediated efflux of IAA/sup -/ down a considerable electrochemical gradient. The efflux is greater from the basal than the apical end of cells and is thought to be responsible for the overall polarity of the process. This step is also the site of action of napthylphthalamic acid (NPA) and herbicides that inhibit polar transport but stimulate net accumulation of auxin by tissues and cells. We are using membrane vesicles as a simplified system for studying the mechanisms involved in the transport and accumulation of auxin. In particular, we are interested in determining the involvement of the transmembrane pH (pH/sub o/ < pH/sub i/) and voltage gradients (K/sup +/ diffusion potential, (K/sup +/)/sub in/ > (K/sup +/)/sub out/) in IAA uptake. 19 refs., 6 figs.

  10. Apolipoprotein D Transgenic Mice Develop Hepatic Steatosis through Activation of PPARγ and Fatty Acid Uptake.

    PubMed

    Labrie, Marilyne; Lalonde, Simon; Najyb, Ouafa; Thiery, Maxime; Daneault, Caroline; Des Rosiers, Chrisitne; Rassart, Eric; Mounier, Catherine

    2015-01-01

    Transgenic mice (Tg) overexpressing human apolipoprotein D (H-apoD) in the brain are resistant to neurodegeneration. Despite the use of a neuron-specific promoter to generate the Tg mice, they expressed significant levels of H-apoD in both plasma and liver and they slowly develop hepatic steatosis and insulin resistance. We show here that hepatic PPARγ expression in Tg mice is increased by 2-fold compared to wild type (WT) mice. Consequently, PPARγ target genes Plin2 and Cide A/C are overexpressed, leading to increased lipid droplets formation. Expression of the fatty acid transporter CD36, another PPARgamma target, is also increased in Tg mice associated with elevated fatty acid uptake as measured in primary hepatocytes. Elevated expression of AMPK in the liver of Tg leads to phosphorylation of acetyl CoA carboxylase, indicating a decreased activity of the enzyme. Fatty acid synthase expression is also induced but the hepatic lipogenesis measured in vivo is not significantly different between WT and Tg mice. In addition, expression of carnitine palmitoyl transferase 1, the rate-limiting enzyme of beta-oxidation, is slightly upregulated. Finally, we show that overexpressing H-apoD in HepG2 cells in presence of arachidonic acid (AA), the main apoD ligand, increases the transcriptional activity of PPARγ. Supporting the role of apoD in AA transport, we observed enrichment in hepatic AA and a decrease in plasmatic AA concentration. Taken together, our results demonstrate that the hepatic steatosis observed in apoD Tg mice is a consequence of increased PPARγ transcriptional activity by AA leading to increased fatty acid uptake by the liver. PMID:26083030

  11. Uptake of perfluorinated alkyl acids by hydroponically grown lettuce (Lactuca sativa).

    PubMed

    Felizeter, Sebastian; McLachlan, Michael S; de Voogt, Pim

    2012-11-01

    An uptake study was carried out to assess the potential human exposure to perfluorinated alkyl acids (PFAAs) through the ingestion of vegetables. Lettuce (Lactuca sativa) was grown in PFAA-spiked nutrient solutions at four different concentrations, ranging from 10 ng/L to 10 μg/L. Eleven perfluorinated carboxylic acids (PFCAs) and three perfluorinated sulfonic acids (PFSAs) were analyzed by HPLC-MS/MS. At the end of the experiment, the major part of the total mass of each of the PFAAs (except the short-chain, C4-C7, PFCAs) taken up by plants appeared to be retained in the nonedible part, viz. the roots. Root concentration factors (RCF), foliage/root concentration factors (FRCF), and transpiration stream concentration factors (TSCF) were calculated. For the long chained PFAAs, RCF values were highest, whereas FRCF were lowest. This indicates that uptake by roots is likely governed by sorption of PFAAs to lipid-rich root solids. Translocation from roots to shoots is restricted and highly depending on the hydrophobicity of the compounds. Although the TSCF show that longer-chain PFCAs (e.g., perfluorododecanoic acid) get better transferred from the nutrient solution to the foliage than shorter-chain PFCAs (e.g., perfluoroheptanoic acid), the major fraction of longer-chain PFCAs is found in roots due to additional adsorption from the spiked solution. Due to the strong electron-withdrawing effect of the fluorine atoms the role of the negative charge of the dissociated PFAAs is likely insignificant. PMID:23043263

  12. PDR-type ABC transporter mediates cellular uptake of the phytohormone abscisic acid

    PubMed Central

    Kang, Joohyun; Hwang, Jae-Ung; Kim, Yu-Young; Assmann, Sarah M.; Martinoia, Enrico; Lee, Youngsook

    2010-01-01

    Abscisic acid (ABA) is a ubiquitous phytohormone involved in many developmental processes and stress responses of plants. ABA moves within the plant, and intracellular receptors for ABA have been recently identified; however, no ABA transporter has been described to date. Here, we report the identification of the ATP-binding cassette (ABC) transporter Arabidopsis thaliana Pleiotropic drug resistance transporter PDR12 (AtPDR12)/ABCG40 as a plasma membrane ABA uptake transporter. Uptake of ABA into yeast and BY2 cells expressing AtABCG40 was increased, whereas ABA uptake into protoplasts of atabcg40 plants was decreased compared with control cells. In response to exogenous ABA, the up-regulation of ABA responsive genes was strongly delayed in atabcg40 plants, indicating that ABCG40 is necessary for timely responses to ABA. Stomata of loss-of-function atabcg40 mutants closed more slowly in response to ABA, resulting in reduced drought tolerance. Our results integrate ABA-dependent signaling and transport processes and open another avenue for the engineering of drought-tolerant plants. PMID:20133880

  13. Influence of salinity and temperature on uptake of perfluorinated carboxylic acids (PFCAs) by hydroponically grown wheat (Triticum aestivum L.).

    PubMed

    Zhao, Hongxia; Qu, Baocheng; Guan, Yue; Jiang, Jingqiu; Chen, Xiuying

    2016-01-01

    Perfluoroalkyl substances (PFASs) have recently attracted increasing concerns due to their ubiquitous existence, adverse effects and persistence in environment. This study employed four perfluorinated carboxylic acids (PFCAs) to examine effects of salinity and temperature on the PFAS uptake in wheat, one of the major crops in the North China Plain. Wheat plants were grown in the spiked-PFCA hydroponic culture system at different salinities and temperatures. As expected, salinity and temperature significantly impacted the root uptake and translocation of wheat to four PFCAs, and the concentrations for each of PFCAs in wheat root and shoot increased with increasing salinity and temperature, respectively. PFCA concentrations at high salinity or high temperature were up to thrice those found at low salinity or low temperature. Except for perfluorobutanoic acid, the amount of PFCAs in root was always higher than that in shoot at the ranges of salinity and temperature tested. Additionally salinity and temperature were also capable of influencing the transfer factors (TFs) of four PFCAs, and significant increase was observed in the TFs in response to the increases in salinity and temperature. PMID:27186505

  14. A relationship between vitamin B sub 12 , folic acid, ascorbic acid, and mercury uptake and methylation

    SciTech Connect

    Zorn, N.E.; Smith, J.T. )

    1990-01-01

    Ingestion of megadoses of certain vitamins appears to influence the in vivo methylation of mercuric chloride in guinea pigs. The addition of megadoses of vitamin B{sub 12} fed either singularly or in combination with folic acid resulted in increased methylmercury concentrations in the liver. Moreover, percent methylmercury levels were significantly increased with B{sub 12} treatment in the liver (B{sub 12} only and B{sub 12}/folic acid) and brain (B{sub 12}/vitamin C). Incorporation of high levels of folic acid into the dietary regime also increased the methylmercury concentration particularly in the liver and hair tissues. The addition of vitamin C in the diet, particularly in combination with B{sub 12} (brain) or folic acid (muscle) resulted in increased methylmercury levels in these tissues and percent methylmercury values with B{sub 12} in the muscle and brain tissue.

  15. Root-zone acidity affects relative uptake of nitrate and ammonium from mixed nitrogen sources

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    Soybean plants (Glycine max [L.] Merr. cv Ransom) were grown for 21 days on 4 sources of N (1.0 mM NO3-, 0.67 mM NO3- plus 0.33 mM NH4+, 0.33 mM NO3- plus 0.67 mM NH4+, and 1.0 mM NH4+) in hydroponic culture with the acidity of the nutrient solution controlled at pH 6.0, 5.5, 5.0, and 4.5. Dry matter and total N accumulation of the plants was not significantly affected by N-source at any of the pH levels except for decreases in these parameters in plants supplied solely with NH4+ at pH 4.5. Shoot-to-root ratios increased in plants which had an increased proportion [correction of proporiton] of NH4(+)-N in their nutrient solutions at all levels of root-zone pH. Uptake of NO3- and NH4+ was monitored daily by ion chromatography as depletion of these ions from the replenished hydroponic solutions. At all pH levels the proportion of either ion that was absorbed increased as the ratio of that ion increased in the nutrient solution. In plants which were supplied with sources of NO3- plus NH4+, NH4+ was absorbed at a ratio of 2:1 over NO3- at pH 6.0. As the pH of the root-zone declined, however, NH4+ uptake decreased and NO3- uptake increased. Thus, the NH4+ to NO3- uptake ratio declined with decreases in root-zone pH. The data indicate a negative effect of declining root-zone pH on NH4+ uptake and supports a hypothesis that the inhibition of growth of plants dependent on NH4(+)-N at low pH is due to a decline in NH4+ uptake and a consequential limitation of growth by N stress.

  16. Uptake of Amino Acids and Their Metabolic Conversion into the Compatible Solute Proline Confers Osmoprotection to Bacillus subtilis

    PubMed Central

    Zaprasis, Adrienne; Bleisteiner, Monika; Kerres, Anne; Hoffmann, Tamara

    2014-01-01

    The data presented here reveal a new facet of the physiological adjustment processes through which Bacillus subtilis can derive osmostress protection. We found that the import of proteogenic (Glu, Gln, Asp, Asn, and Arg) and of nonproteogenic (Orn and Cit) amino acids and their metabolic conversion into proline enhances growth under otherwise osmotically unfavorable conditions. Osmoprotection by amino acids depends on the functioning of the ProJ-ProA-ProH enzymes, but different entry points into this biosynthetic route are used by different amino acids to finally yield the compatible solute proline. Glu, Gln, Asp, and Asn are used to replenish the cellular pool of glutamate, the precursor for proline production, whereas Arg, Orn, and Cit are converted into γ-glutamic semialdehyde/Δ1-pyrroline-5-carboxylate, an intermediate in proline biosynthesis. The import of Glu, Gln, Asp, Asn, Arg, Orn, and Cit did not lead to a further increase in the size of the proline pool that is already present in osmotically stressed cells. Hence, our data suggest that osmoprotection of B. subtilis by this group of amino acids rests on the savings in biosynthetic building blocks and energy that would otherwise have to be devoted either to the synthesis of the proline precursor glutamate or of proline itself. Since glutamate is the direct biosynthetic precursor for proline, we studied its uptake and found that GltT, an Na+-coupled symporter, is the main uptake system for both glutamate and aspartate in B. subtilis. Collectively, our data show how effectively B. subtilis can exploit environmental resources to derive osmotic-stress protection through physiological means. PMID:25344233

  17. Elevated free fatty acid uptake via CD36 promotes epithelial-mesenchymal transition in hepatocellular carcinoma

    PubMed Central

    Nath, Aritro; Li, Irene; Roberts, Lewis R.; Chan, Christina

    2015-01-01

    Hepatocellular carcinoma (HCC) is the second-leading cause of cancer-related death worldwide, and the factors influencing HCC progression are poorly understood. Here we reveal that HCC progression via induction of epithelial-mesenchymal transition (EMT) is closely associated with the expression of CD36/fatty acid translocase and elevated free fatty acid (FFA) levels. Although obesity is manifested as elevated FFA levels, the degree of EMT was not associated with the body mass index of the patients, highlighting the specific roles of CD36 and FFA uptake. Treatment of human liver cancer cell lines with FFAs exacerbated the EMT phenotype, whereas chemical inhibition of CD36 mitigated these effects. Furthermore, the Wnt and TGF-β signaling pathways were activated upon FFA treatment, potentially acting as upstream activators of the EMT program. These results provide the first direct evidence associating CD36 and elevated FFAs with HCC progression. PMID:26424075

  18. Gold nanoparticles with different amino acid surfaces: serum albumin adsorption, intracellular uptake and cytotoxicity.

    PubMed

    Cai, Huanxin; Yao, Ping

    2014-11-01

    Gold nanoparticles with aspartate, glycine, leucine, lysine, and serine surfaces were produced from the mixed solutions of HAuCl4 and respective amino acids via UV irradiation. The amino acids bind to the nanoparticle surfaces via amine groups and their carboxylic groups extend out to stabilize the nanoparticles. The nanoparticles have diameters of 15-47 nm in pH 7.4 aqueous solution and have diameters of 62-73 nm after 48 h incubation in cell culture containing serum. The nanoparticles adsorb human and bovine serum albumins on their surfaces by specific interactions, characterized by the intrinsic fluorescence quenching of the albumins. The albumin adsorption effectively decreases the aggregation of the nanoparticles in cell culture and also decreases the intracellular uptake of the nanoparticles. The gold nanoparticles produced from leucine and lysine, which have amphiphilic groups on their surfaces, present better biocompatibility than the other gold nanoparticles. PMID:25466455

  19. Tissue-selective uptake of pravastatin in rats: contribution of a specific carrier-mediated uptake system.

    PubMed

    Yamazaki, M; Tokui, T; Ishigami, M; Sugiyama, Y

    1996-12-01

    Previously we demonstrated that a hydrophilic HMG-CoA reductase inhibitor, pravastatin, was actively taken up by the liver via the 'multispecific anion transporter' using isolated rat hepatocytes (M. Yamazaki, H. Suzuki, M. Hanano, T. Tokui, T. Komai, and Y. Sugiyama, Am. J. Physiol., 264, G36-G44 (1993)). Such a carrier-mediated uptake of pravastatin may contribute to the liver selective inhibition of the cholesterol synthesis in vivo. To examine the early-phase tissue distribution of this drug, we carried out a pharmacokinetic and tissue distribution analysis of pravastatin in rats. After i.v. bolus administration of [14C]pravastatin, the time profiles of [14C]radioactivity in plasma and several tissues were determined to calculate the tissue uptake clearance (CLuptake). Among the tissues examined, liver accounted for the major uptake (CLuptake,liver = 22.8 mL min-1 kg-1), followed by kidney (CLuptake,kidney (GFR corrected) = 2.36 mL min-1 kg-1). Other tissues showed no significant uptake (less than 0.2 mL min-1 kg-1). After portal vein administration, the distribution to the liver became much larger than that to the kidney due to the extensive first-pass removal by the liver. The first-pass hepatic uptake ratio was estimated as 0.66. Administering a range of doses (0.4-400 mumol kg-1) intravenously, an increase in early-phase half-life and a decrease in CLuptake,liver were observed simultaneously at doses over 40 mumol kg-1. In addition, CLuptake,kidney decreased at doses over 4 mumol kg-1. The effect of DBSP or PAH co-infusion (i.e. typical substrates for the transport system for organic anions in liver and kidney, respectively) on the initial uptake of pravastatin was also examined. DBSP clearly inhibited both the hepatic and renal uptake; however, PAH did not reduce the hepatic uptake of pravastatin although it inhibited the renal uptake. The transport systems in liver and kidney are thus considered different, based on the different saturability and

  20. Increased hepatic Fatty Acid uptake and esterification contribute to tetracycline-induced steatosis in mice.

    PubMed

    Choi, You-Jin; Lee, Chae-Hyeon; Lee, Kang-Yo; Jung, Seung-Hwan; Lee, Byung-Hoon

    2015-06-01

    Tetracycline induces microvesicular steatosis, which has a poor long-term prognosis and a higher risk of steatohepatitis development compared with macrovesicular steatosis. Recent gene expression studies indicated that tetracycline treatment affects the expression of many genes associated with fatty acid transport and esterification. In this study, we investigated the role of fatty acid transport and esterification in tetracycline-induced steatosis. Intracellular lipid accumulation and the protein expression of fatty acid translocase (FAT or CD36) and diacylglycerol acyltransferase (DGAT) 2 were increased in both mouse liver and HepG2 cells treated with tetracycline at 50 mg/kg (intraperitoneal injection, i.p.) and 100 μM, respectively. Tetracycline increased the cellular uptake of boron-dipyrromethene-labeled C16 fatty acid, which was abolished by CD36 RNA interference. Oleate-induced cellular lipid accumulation was further enhanced by co-incubation with tetracycline. Tetracycline downregulated extracellular signal-regulated kinase (ERK) phosphorylation, which negatively regulated DGAT2 expression. U0126, a specific ERK inhibitor, also increased DGAT2 expression and cellular lipid accumulation. DGAT1 and 2 knock-down with specific small interfering (si)-RNA completely abrogated the steatogenic effect of tetracycline in HepG2 cells. Taken together, our data showed that tetracycline induces lipid accumulation by facilitating fatty acid transport and triglyceride esterification by upregulating CD36 and DGAT2, respectively. PMID:25745068

  1. Endothelial cell damage after gamma-irradiation in vitro: impaired uptake of alpha-aminoisobutyric acid. [137Cs

    SciTech Connect

    Kwock, L.; Douglas, W.H.; Lin, P.S.; Baur, W.E.; Fanburg, B.L.

    1982-01-01

    The effects of gamma-irradiation with a cesium-137 source were assessed on endothelial cells isolated from bovine pulmonary arteries and maintained in culture. The radiobiologic parameters that characterize the dose-response survival curve for these cells, expressed as mean +/- SD were found to be n . 1.6 +/- 0.2, Dq . 71 +/- 13 rads, and Do . 161 +/- 35 rads, indicating a relatively low capacity of these cells to accumulate or repair radiation damage. Increasing doses of radiation led to decreasing uptake by endothelial cells of (14C)2-aminoisobutyric acid (AIB), a Na+-dependent and nonmetabolizable amino acid. A dose of 500 rads, which caused marked inhibition of cell survival, resulted in a 45% decrease in AIB uptake at 6 h and a 69% decrease in uptake at 24 h after irradiation. No morphologic abnormality was noted in these cells by light microscopy at 24 h after this dose of radiation. Bovine pulmonary artery fibroblasts, on the other hand, showed no significant impairment in uptake of AIB 24 h after exposure to doses of radiation as high as 5,000 rads. The uptake by endothelial cells of (14C)1-aminocyclopentane-1-carboxylic acid, an amino acid transported by a Na+-independent process, was not influenced by 5,000 rads of radiation. Our studies show that endothelial cells are sensitive to radiation and that impaired Na+-dependent uptake of AIB represents an early event in radiation damage to the endothelial cell.

  2. Phytochrome controlled C-sucrose uptake into etiolated pea buds: effects of gibberellic Acid and other substances.

    PubMed

    Goren, R; Galston, A W

    1967-08-01

    The previously reported red light enhancement of (14)C-sucrose uptake into etiolated pea buds is inhibited by gibberellic acid applied no later than 2 hours after the light. Auxins, cytokinins and inhibitors of gibberellin biosynthesis are without effect, either alone or in the presence of gibberellic acid. PMID:16656618

  3. Nitrated fatty acids reverse pulmonary fibrosis by dedifferentiating myofibroblasts and promoting collagen uptake by alveolar macrophages

    PubMed Central

    Reddy, Aravind T.; Lakshmi, Sowmya P.; Zhang, Yingze; Reddy, Raju C.

    2014-01-01

    Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal disease, thought to be largely transforming growth factor β (TGFβ) driven, for which there is no effective therapy. We assessed the potential benefits in IPF of nitrated fatty acids (NFAs), which are unique endogenous agonists of peroxisome proliferator-activated receptor γ (PPARγ), a nuclear hormone receptor that exhibits wound-healing and antifibrotic properties potentially useful for IPF therapy. We found that pulmonary PPARγ is down-regulated in patients with IPF. In vitro, knockdown or knockout of PPARγ expression in isolated human and mouse lung fibroblasts induced a profibrotic phenotype, whereas treating human fibroblasts with NFAs up-regulated PPARγ and blocked TGFβ signaling and actions. NFAs also converted TGFβ to inactive monomers in cell-free solution, suggesting an additional mechanism through which they may inhibit TGFβ. In vivo, treating mice bearing experimental pulmonary fibrosis with NFAs reduced disease severity. Also, NFAs up-regulated the collagen-targeting factor milk fat globule-EGF factor 8 (MFG-E8), stimulated collagen uptake and degradation by alveolar macrophages, and promoted myofibroblast dedifferentiation. Moreover, treating mice with established pulmonary fibrosis using NFAs reversed their existing myofibroblast differentiation and collagen deposition. These findings raise the prospect of treating IPF with NFAs to halt and perhaps even reverse the progress of IPF.—Reddy, A. T., Lakshmi, S. P., Zhang, Y., Reddy, R. C. Nitrated fatty acids reverse pulmonary fibrosis by dedifferentiating myofibroblasts and promoting collagen uptake by alveolar macrophages. PMID:25252739

  4. Increased brain uptake of targeted nanoparticles by adding an acid-cleavable linkage between transferrin and the nanoparticle core.

    PubMed

    Clark, Andrew J; Davis, Mark E

    2015-10-01

    Most therapeutic agents are excluded from entering the central nervous system by the blood-brain barrier (BBB). Receptor mediated transcytosis (RMT) is a common mechanism used by proteins, including transferrin (Tf), to traverse the BBB. Here, we prepared Tf-containing, 80-nm gold nanoparticles with an acid-cleavable linkage between the Tf and the nanoparticle core to facilitate nanoparticle RMT across the BBB. These nanoparticles are designed to bind to Tf receptors (TfRs) with high avidity on the blood side of the BBB, but separate from their multidentate Tf-TfR interactions upon acidification during the transcytosis process to allow release of the nanoparticle into the brain. These targeted nanoparticles show increased ability to cross an in vitro model of the BBB and, most important, enter the brain parenchyma of mice in greater amounts in vivo after systemic administration compared with similar high-avidity nanoparticles containing noncleavable Tf. In addition, we investigated this design with nanoparticles containing high-affinity antibodies (Abs) to TfR. With the Abs, the addition of the acid-cleavable linkage provided no improvement to in vivo brain uptake for Ab-containing nanoparticles, and overall brain uptake was decreased for all Ab-containing nanoparticles compared with Tf-containing ones. These results are consistent with recent reports of high-affinity anti-TfR Abs trafficking to the lysosome within BBB endothelium. In contrast, high-avidity, Tf-containing nanoparticles with the acid-cleavable linkage avoid major endothelium retention by shedding surface Tf during their transcytosis. PMID:26392563

  5. Blood-brain barrier and brain fatty acid uptake: Role of arachidonic acid and PGE2.

    PubMed

    Murphy, Eric J

    2015-12-01

    How do fatty acids enter the brain and what role, if any, do membrane and cytosolic fatty acid binding proteins have on facilitating this process? This is a fundamental question that many lipid neurochemists will freely admit they cannot answer in any kind of definitive manner. A study by Dalvi and colleagues in this issue of the Journal of Neurochemistry now adds to our knowledge in this field. Among other important observations, their experiments demonstrate that a physiological level of arachidonic acid (ARA), that could be associated with many different physiological and pathophysiological states, increases permeability in a model of the human blood brain barrier (BBB) in the absence of cytokines. This last point is very important as it suggests increases in BBB permeability may occur in situations other than those associated with increases in tumor necrosis factor a (TNFα) and interleukin1b (IL1β), giving additional options for developing drugs impacting BBB permeability. PMID:26383055

  6. Nanomolar Caffeic Acid Decreases Glucose Uptake and the Effects of High Glucose in Endothelial Cells

    PubMed Central

    Natarelli, Lucia; Ranaldi, Giulia; Leoni, Guido; Roselli, Marianna; Guantario, Barbara; Comitato, Raffaella; Ambra, Roberto; Cimino, Francesco; Speciale, Antonio; Virgili, Fabio; Canali, Raffaella

    2015-01-01

    Epidemiological studies suggest that moderate and prolonged consumption of coffee is associated with a reduced risk of developing type 2 diabetes but the molecular mechanisms underlying this effect are not known. In this study, we report the effects of physiological concentrations of caffeic acid, easily achievable by normal dietary habits, in endothelial cells cultured in 25 mM of glucose (high glucose, HG). In HG, the presence of 10 nM caffeic acid was associated with a decrease of glucose uptake but not to changes of GLUT-1 membrane localization or mRNA levels. Moreover, caffeic acid countered HG-induced loss of barrier integrity, reducing actin rearrangement and FITC-dextran passage. The decreased flux of glucose associated to caffeic acid affected HG induced apoptosis by down-regulating the expression of initiator (caspase 8 and 9) and effector caspases (caspase 7 and 3) and by increasing the levels of phosphorylated Bcl-2. We also observed that caffeic acid in HG condition was associated to a reduction of p65 subunit nuclear levels with respect to HG alone. NF-κB activation has been shown to lead to apoptosis in HG treated cells and the analysis of the expression of a panel of about 90 genes related to NF-κB signaling pathway revealed that caffeic acid significantly influenced gene expression changes induced by HG. In conclusion, our results suggest that caffeic acid, decreasing the metabolic stress induced by HG, allows the activation of survival mechanisms mediated by a different modulation of NF-κB-related signaling pathways and to the activation of anti-apoptotic proteins. PMID:26544184

  7. Uptake of HCl and HOCl onto sulfuric acid. Solubilities, diffusivities, and reaction

    SciTech Connect

    Hanson, D.R.; Ravishankara, A.R. Univ. of Colorado, Boulder, CO )

    1993-11-25

    The interaction of HOCl and HCl vapors with liquid sulfuric acid surfaces was studied in a flow tube equipped with chemical ionization mass spectrometry detection. Time-dependent uptake of HCl and HOCl was measured. A methodology for deriving the value of the quantity H[radical]D[sub 1], (the product of the Henry's law coefficient and the square root of the liquid-phase diffusion coefficient) is discussed. The partial pressures of HCl over HCl-doped sulfuric acid solutions were also measured to directly determine H for HCl (H[sub HCl]*). Using the measured values of H[sub HCl]* and H[sub HCl]*[radical]D[sub 1], the value of D[sub 1] for HCl in 50 wt % sulfuric acid was extracted. Values for H[sub HOCl] and for the second-order rate coefficient for the reaction between dissolved HOCl and HCl were also obtained. The application of these results to modeling stratospheric heterogeneous processes in sulfuric acid aerosols is discussed. 31 refs., 14 refs., 3 tabs.

  8. Water uptake of internally mixed ammonium sulfate and dicarboxylic acid particles probed by infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Miñambres, Lorena; Méndez, Estíbaliz; Sánchez, María N.; Castaño, Fernando; Basterretxea, Francisco J.

    2013-05-01

    Tropospheric aerosols are usually mixtures of inorganic and organic compounds in variable proportions, and the relative amount of organic fraction can influence the hygroscopic properties of the particles. Infrared spectra of submicrometer internally mixed dry particles of ammonium sulfate (AS) with various dicarboxylic acids (oxalic, malonic, maleic, glutaric and pimelic) have been measured in an aerosol flow tube at several solute mass ratios. The spectra show a notable broadening in the bandwidth of sulfate ion ν3 vibrational band near 1115 cm-1 with respect to pure AS. We attribute these perturbations, that are biggest at AS/organic acid mass ratio near unity, to intermolecular interactions between inorganic ions and organic acid molecules in the internally mixed solids. The water uptake behavior of internally mixed particles has been measured by recording the infrared integrated absorbance of liquid water as a function of relative humidity (RH). The amount of water present in the particles prior to deliquescence correlates partially with the water solubilities of the dicarboxylic acids, and also with the relative magnitudes of intermolecular interactions in the internally mixed dry solids. Phase change of ammonium sulfate in the internally mixed particles with RH has been spectrally monitored, and it is shown that water uptaken before full deliquescence produces structural changes in the particles that are revealed by their vibrational spectra.

  9. Effect of fatty acid coatings on ozone uptake to deliquesced KI/NaCl aerosol particles

    NASA Astrophysics Data System (ADS)

    Ammann, M.; Rouvière, A.

    2009-12-01

    Phase transfer kinetics of gas phase oxidants may limit oxidative aging of aerosol particles. The aim of this work is to study the role of amphiphilic organic aerosol constituents on the kinetics of phase transfer of gaseous species to the bulk aqueous phase. The effect of (C9-C20) fatty acid surfactants on the phase transfer of ozone to deliquesced potassium iodide and sodium chloride have been investigated. Some other experiments of ozone uptake have been performed with different mixtures and proportions of fatty acids. The kinetic experiments were performed in an aerosol flow tube at room temperature and atmospheric pressure. To obtain deliquesced inorganic particles, the relative humidity was adjusted in the range of 75% to 80%. It is shown that the fatty acids in monolayer quantities may substantially inhibit the phase transfer of ozone to deliquesced particles. The results showed that especially the C15-C20 limit the mass transfer of ozone to the aqueous phase, whereby the magnitude of this effect was following the monolayer properties of the fatty acids. It was also possible to determine a resistance of such films to the transfer of ozone to the bulk phase.

  10. A sodium-indpendent low affinity transport system for neutral amino acids in rabbit ileal mucosa.

    PubMed Central

    Paterson, J Y; Sepúlveda, F V; Smith, M W

    1980-01-01

    1. The kinetic parameters for serine, alanine and methionine uptake by rabbit ileal mucosa have been determined in the absence of Na. 2. Uptake of all three amino acids took place through a single mediated system. The apparent Km values of serine, alanine and methionine for this system were equal to their respective apparent K1 values (approximately 89, 75 and 23 mM respectively). 3. Autoradiography was used to measure the cellular location of alanine uptake by rabbit ileum. Approximately 80% of the total uptake took place in the upper third of each villus. This uptake was reduced by 75% either by removal of Na or addition of serine. The proportional distribution of Na-dependent and Na-independent alanine uptakes along the villus was found to be equal. 4. The kinetic properties of the low affinity uptake mechanism for neutral amino acids, seen in the absence of Na, were virtually identical with those of one of the uptake mechanisms seen previously in the presence of Na. 5. The low affinity uptake mechanism appears to be Na-independent. It is suggested that the Na-coupled uptake of amino acid takes place through the high affinity system. PMID:7359411

  11. How fulvic acid affects heavy metal uptake on the muscovite (001) surface

    NASA Astrophysics Data System (ADS)

    Lee, S.; Fenter, P.; Park, C.; Sturchio, N. C.; Nagy, K.

    2009-12-01

    Understanding the molecular-scale reactions at mineral-solution interfaces is crucial for developing predictive models to assess the transport and bioavailability of dissolved heavy metals in the surface environment. We investigated the vertical distribution of divalent heavy metals (Cu, Zn, Sr, Hg, and Pb) adsorbed at the muscovite (001)-solution interface in the absence and presence of fulvic acid (FA) using interface-specific specular X-ray reflectivity combined with element-specific resonant anomalous X-ray reflectivity with a sub-angstrom resolution. The experimental solutions were prepared using 1-10 mmol/kg metal nitrates with or without 100 mg/kg Elliott Soil Fulvic Acid II or Suwannee River Fulvic Acid from the International Humic Substances Society at pH 2-5.5. Reflectivity data were measured at the Advanced Photon Source, Argonne National Laboratory. In the absence of FA, the results show a complex picture in which there are three distinct adsorbed species that coexist at the interface: classical inner- and outer-sphere complexes plus a third OS fraction that is more broadly distributed at heights farther from the surface than the other species. Systematic trends in cation adsorption show that these three species are correlated and that their partitioning can be explained by thermodynamic equilibrium among these three species which is controlled mainly by cation hydration energy. The presence of dissolved FA modifies heavy metal uptake by two different mechanisms: it can form complexes with metal cations in solution and adsorb on muscovite as metal-organic complexes when the metal has a relatively high affinity for organic matter. In this case, the adsorbed metal cation shows a characteristic broad distribution within the entire film, resulting in formation of a more electron-dense and thicker organic film on muscovite compared to that without metals. Metals with lower organophilicity show that the enhanced metal uptake occurs mainly within the outer

  12. Brain Uptake of the Drug of Abuse γ-Hydroxybutyric Acid in Rats

    PubMed Central

    Roiko, Samuel A.; Felmlee, Melanie A.

    2012-01-01

    γ-Hydroxybutyric acid (GHB) is an endogenous compound and a substrate for the ubiquitous monocarboxylate transporter (MCT) family. GHB is also a drug of abuse due to its sedative/hypnotic and euphoric effects, with overdoses resulting in toxicity and death. The goal of this study was to characterize the distribution of GHB into the brain using in vivo microdialysis and in vitro uptake studies and to determine concentration-effect relationships for GHB in a rat animal model. GHB was administered to rats (400, 600, and 800 mg/kg i.v.), and blood, dialysate, and urine were collected for 6 h post-GHB administration. The GHB plasma and extracellular fluid (ECF) concentration-time profiles revealed that GHB concentrations in ECF closely followed plasma GHB concentrations. Sleep time increased in a dose-dependent manner (91 ± 18, 134 ± 11, and 168 ± 13 min, for GHB 400, 600, and 800 mg/kg, respectively). GHB partitioning into brain ECF was not significantly different at 400, 600, and 800 mg/kg. GHB uptake in rat and human brain endothelial cells exhibited concentration dependence. The concentration-dependent uptake of GHB at pH 7.4 was best-fit to a single-transporter model [Km = 18.1 mM (human), 23.3 mM (rat), Vmax = 248 and 258 pmol · mg−1 · min−1 for human and rat, respectively]. These findings indicate that although GHB distribution into the brain is mediated via MCT transporters, it is not capacity-limited over the range of doses studied in this investigation. PMID:22019629

  13. Uptake of silica covered Quantum Dots into living cells: Long term vitality and morphology study on hyaluronic acid biomaterials.

    PubMed

    D'Amico, Michele; Fiorica, Calogero; Palumbo, Fabio Salvatore; Militello, Valeria; Leone, Maurizio; Dubertret, Benoit; Pitarresi, Giovanna; Giammona, Gaetano

    2016-10-01

    Quantum Dots (QDs) are promising very bright and stable fluorescent probes for optical studies in the biological field but water solubility and possible metal bio-contamination need to be addressed. In this work, a simple silica-QD hybrid system is prepared and the uptake in bovine chondrocytes living cells without any functionalization of the external protective silica shield is demonstrated. Moreover, long term treated cells vitality (up to 14days) and the transfer of silica-QDs to the next cell generations are here reported. Confocal fluorescence microscopy was also used to determine the morphology of the so labelled cells and the relative silica-QDs distribution. Finally, we employ silica-QD stained chondrocytes to characterize, as proof of concept, hydrogels obtained from an amphiphilic derivative of hyaluronic acid (HA-EDA-C18) functionalized with different amounts of the RGD peptide. PMID:27287118

  14. Maintenance of Different Mannitol Uptake Systems during Starvation in Oxidative and Fermentative Marine Bacteria

    PubMed Central

    Davis, Claire L.; Robb, Frank T.

    1985-01-01

    The mannitol uptake systems in marine Vibrio and Pseudomonas isolates from the kelp beds off the South African west coast were examined. The fermentative Vibrio isolate possessed a constitutive rapid mannitol uptake system and also a soluble mannitol-1-phosphate dehydrogenase, indicative of a mannitol phosphotransferase system. An inducible, relatively less active mannitol uptake system was detected in the oxidative Pseudomonas isolate, and this strain possessed a mannitol dehydrogenase. The maintenance of these systems during starvation survival was studied. The Vibrio isolate maintained its initial uptake system for approximately 5 weeks of starvation, after which time the uptake system was replaced by one with a higher affinity for mannitol. The mannitol transport system of the Pseudomonas isolate was depressed early in starvation (30 h) but could be readily induced by exogenous mannitol after 6 weeks of starvation. The relative proportions of mannitol which was incorporated and respired were determined in starved Vibrio and Pseudomonas strains. PMID:16346909

  15. A novel glyceryl monoolein-bearing cubosomes for gambogenic acid: Preparation, cytotoxicity and intracellular uptake.

    PubMed

    Luo, Qing; Lin, Tongyuan; Zhang, Cai Yuan; Zhu, Tingting; Wang, Lei; Ji, Zhaojie; Jia, Buyun; Ge, Tao; Peng, Daiyin; Chen, Weidong

    2015-09-30

    Lyotropic cubic liquid crystalline nanoparticles, also known as 'cubosomes', have been tested as effective carriers for a variety of drugs due to their ability to enhance delivery efficiency and reduced drug side effects. Cubosomes are colloidal carriers composed of biodegradable Glyceryl monooleate and F127. Being composed of well tolerable and physiological materials, these carriers are well tolerated, compatible and non-toxic. In this study, therefore, we developed a novel, water-soluble, glyceryl monooleate and F127 based multiblock copolymer for Gambogenic acid (GNA) by emulsion-evaporation and low temperature-solidification technique. Physicochemical properties, in vitro cytotoxicity, cellular uptake and in vivo pharmacokinetic of GNA-loaded cubosomes (GNA-Cubs) were investigated. The results revealed that GNA-Cubs were spherical or ellipsoidal monocellular by dynamic light scattering, meanwhile, 150-250nm in mean size with narrow polydispersity indexas determined by transmission electron microscopy. Small angle X-ray scattering indicated that GNA-Cubs retain the Pn3m cubic symmetry. Compared with GNA solution, GNA-Cubs exhibited markedly prolonged inhibitory activity in SMMC-7721 cells, as well as time-dependent increases in intra-cellular uptake. Furthermore, in vivo pharmacokinetic study showed that the Cmax values and the AUC of GNA-Cubs were higher than GNA solution approximately 1.2-fold and 9.1-fold, respectively. In conclusion, the results showed that the cubic liquid crystalline nanoparticles could be a potentially nanocarrier in the delivery of GNA for cancer therapy. PMID:26209071

  16. Uptake of Cs and Sr radionuclides within oleic acid coated nanomagnetite-hematite composite

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, J.; Sengupta, Pranesh; Sen, D.; Mazumdar, S.; Tyagi, A. K.

    2015-12-01

    Nano-sized magnetic composite sorbent material like nanomagnetite - nanohematite has been synthesized for uptake of cesium and strontium ions from low level environmental effluents in effective decontamination from waste water. Synthesis of material was based on co-precipitation route and in situ coating of oleic acid on magnetite-hematite nanocomposite. Magnetic properties were studied for both the uncoated as prepared and coated nanocomposite materials. The magnetization curves showed no hysteresis or remnant magnetization. Both the materials exhibited super-paramagnetism. Saturation magnetization of the coated nanocomposite was found to be 30 emu/g whereas for as prepared nanocomposite it was 64 emu/g. Detailed characterizations of the materials was carried out by X ray diffraction and Transmission electron microscopic techniques and the grain sizes were found to vary between 10 and 15 nm range. Sorption experiments on cesium and strontium were carried out by batch mode equilibrium study. The uptake studies were performed by Atomic Absorption Spectroscopy for cesium ions and inductively coupled Plasma - Atomic Emission Spectroscopy for strontium ions. Size distributions of the particle were measure through Small Angle X ray Scattering (SAXS) experiment. Shifting in weak repulsive potential facilitates enhanced sorption for more period of time in stable condition in comparison of uncoated nanocomposite which forms larger aggregates.

  17. Uptake and release of adrenal ascorbic acid in the guinea pig after injection of ACTH

    SciTech Connect

    Kipp, D.E.; Rivers, J.M.

    1987-09-01

    The effect of a single injection of ACTH (3 IU/100 g body weight) on the distribution of ascorbic acid (AA) and radiolabeled AA in 20 tissues was studied in adult male guinea pigs consuming 500 mg AA/kg diet. Saline- or ACTH-injected animals were simultaneously injected with (1-/sup 14/C)AA, and killed at 0.5, 1, 2, 4 and 6 h after injection. There was no significant difference between treatments in the weight of any tissue over the 6-h experimental period. As anticipated, the concentration of AA in the adrenals of animals injected with ACTH was 33% of that of animals injected with saline at 4 h. Unexpectedly, the concentration of radiolabeled AA in the adrenals at 0.5 h after ACTH injection was 172% of that after saline injection. The concentration of radiolabeled AA in the adrenal of the saline-injected animals increased slowly over time to reach a level similar to that of ACTH-injected animals by 6 h. There was no effect of ACTH on the level of AA or uptake in any of the other tissues examined. These results demonstrate that a single dose of ACTH markedly influences the retention of AA in the adrenal gland without similarly altering retention of AA in other tissues. Furthermore, ACTH treatment causes both accelerated uptake and release of AA into the adrenals.

  18. Neuregulin 1 Controls Glutamate Uptake by Up-regulating Excitatory Amino Acid Carrier 1 (EAAC1).

    PubMed

    Yu, Ha-Nul; Park, Woo-Kyu; Nam, Ki-Hoan; Song, Dae-Yong; Kim, Hye-Sun; Baik, Tai-Kyoung; Woo, Ran-Sook

    2015-08-14

    Neuregulin 1 (NRG1) is a trophic factor that is thought to have important roles in the regulating brain circuitry. Recent studies suggest that NRG1 regulates synaptic transmission, although the precise mechanisms remain unknown. Here we report that NRG1 influences glutamate uptake by increasing the protein level of excitatory amino acid carrier (EAAC1). Our data indicate that NRG1 induced the up-regulation of EAAC1 in primary cortical neurons with an increase in glutamate uptake. These in vitro results were corroborated in the prefrontal cortex (PFC) of mice given NRG1. The stimulatory effect of NRG1 was blocked by inhibition of the NRG1 receptor ErbB4. The suppressed expression of ErbB4 by siRNA led to a decrease in the expression of EAAC1. In addition, the ablation of ErbB4 in parvalbumin (PV)-positive neurons in PV-ErbB4(-/-) mice suppressed EAAC1 expression. Taken together, our results show that NRG1 signaling through ErbB4 modulates EAAC1. These findings link proposed effectors in schizophrenia: NRG1/ErbB4 signaling perturbation, EAAC1 deficit, and neurotransmission dysfunction. PMID:26092725

  19. Root uptake and translocation of perfluorinated alkyl acids by three hydroponically grown crops.

    PubMed

    Felizeter, Sebastian; McLachlan, Michael S; De Voogt, Pim

    2014-04-16

    Tomato, cabbage, and zucchini plants were grown hydroponically in a greenhouse. They were exposed to 14 perfluorinated alkyl acids (PFAAs) at four different concentrations via the nutrient solution. At maturity the plants were harvested, and the roots, stems, leaves, twigs (where applicable), and edible parts (tomatoes, cabbage head, zucchinis) were analyzed separately. Uptake and transfer factors were calculated for all plant parts to assess PFAA translocation and distribution within the plants. Root concentration factors were highest for long-chain PFAAs (>C11) in all three plant species, but these chemicals were not found in the edible parts. All other PFAAs were present in all above-ground plant parts, with transpiration stream concentration factors (TSCFs) of 0.05-0.25. These PFAAs are taken up with the transpiration stream and accumulate primarily in the leaves. Although some systematic differences were observed, overall their uptake from nutrient solution to roots and their further distribution within the plants were similar between plant species and among PFAAs. PMID:24646206

  20. Laboratory Experiments on Nitric Acid Uptake by a Meteoric Smoke Analogue

    NASA Astrophysics Data System (ADS)

    James, A.; Frankland, V. L.; Plane, J. M.

    2013-12-01

    Amorphous olivine particles have been synthesised using the sol-gel technique to provide analogues of meteoric smoke particles. A Knudsen cell was used to measure an uptake coefficient of nitric acid on meteoric smoke of 3 × 4 x 10-3. Employing this parameter in an atmospheric model of smoke transport suggests that in the polar winter vortex, where meteoric smoke is concentrated (and photolysis is negligible) the lifetime of HNO3 with respect to heterogeneous removal is around 4 months, which is similar to the length of the polar winter. One uncertainty in this estimate is the size of the cosmic dust input to the atmosphere (assumed here to be 20 t d-1, one quarter of which ablates).

  1. Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

    DOEpatents

    Rau, Gregory Hudson

    2012-05-15

    A system is described for forming metal hydroxide from a metal carbonate utilizing a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate, in particular water-insoluble calcium carbonate or magnesium carbonate, is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide. Among other uses, the metal hydroxide formed can be employed to absorb acid gases such as carbon dioxide from a gas mixture. The invention can also generate hydrogen and oxidative gases such as oxygen or chlorine.

  2. [Separate evaluation of beta-methyl fatty acid uptake and perfusion in rat myocardium].

    PubMed

    Taniguchi, M; Bunkou, H; Nakajima, K; Taki, J; Muramori, A; Matsunari, I; Nambu, I; Shiirei, Y; Tonami, N; Hisada, K

    1989-12-01

    The kinetics and distribution of I-125 beta-methyl iodophenyl pentadecanoic acid (BMIPP) in rat's heart were studied for separate evaluation of perfusion and metabolism. Tl-201 and BMIPP were simultaneously injected. The experimental groups consisted of control (C), glucose (G) and sodium lactate loaded group (L). In C, myocardial uptake at 5 minutes after BMIPP injection was 3.60% ID/g and remained constant up to 60 minutes. The myocardium/lung ratio (2.44) and the myocardium/muscle ratio (4.55) of BMIPP were almost equal to those of Tl-201. But myocardium/liver ratio was low (1.31). In G, myocardial uptake of BMIPP (1.94 +/- 0.36% ID/g) and g-BMIPP/Tl (0.31 +/- 0.03) at 15 minutes after injection were significantly decreased (p less than 0.001) than those of C (3.16 +/- 0.18% ID/g and 0.48 +/- 0.05). In L. myocardial perfusion was decreased and g-BMIPP/Tl (0.73 +/- 0.14) was significantly higher (p less than 0.01) than those of C. Coefficient of variance of the density within a myocardium, and the ratio of inner to outer layer of myocardium (I/O ratio) were calculated from autoradiogram by videodensitometry. The myocardial distribution of BMIPP was more inhomogeneous, and the I/O ratio was lower than that of Tl-201, although these were not specific for metabolic interventions. In conclusion BMIPP is suitable for SPECT imaging and dual nuclide imaging by BMIPP and Tl-201 will provide informations about myocardial fatty acid metabolism and perfusion. PMID:2622083

  3. 21 CFR 862.1715 - Triiodothyronine uptake test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... albumin of serum and plasma. The device provides an indirect measurement of thyrkoxine levels in serum and plasma. Measurements of triiodothyronine uptake are used in the diagnosis and treatment of...

  4. 21 CFR 862.1715 - Triiodothyronine uptake test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... albumin of serum and plasma. The device provides an indirect measurement of thyrkoxine levels in serum and plasma. Measurements of triiodothyronine uptake are used in the diagnosis and treatment of...

  5. 21 CFR 862.1715 - Triiodothyronine uptake test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... albumin of serum and plasma. The device provides an indirect measurement of thyrkoxine levels in serum and plasma. Measurements of triiodothyronine uptake are used in the diagnosis and treatment of...

  6. 21 CFR 862.1715 - Triiodothyronine uptake test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... albumin of serum and plasma. The device provides an indirect measurement of thyrkoxine levels in serum and plasma. Measurements of triiodothyronine uptake are used in the diagnosis and treatment of...

  7. 21 CFR 862.1715 - Triiodothyronine uptake test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... albumin of serum and plasma. The device provides an indirect measurement of thyrkoxine levels in serum and plasma. Measurements of triiodothyronine uptake are used in the diagnosis and treatment of...

  8. Metabolic influence of lead on polyhydroxyalkanoates (PHA) production and phosphate uptake in activated sludge fed with glucose or acetic acid as carbon source.

    PubMed

    You, Sheng-Jie; Tsai, Yung-Pin; Cho, Bo-Chuan; Chou, Yi-Hsiu

    2011-09-01

    Sludge in a sequential batch reactor (SBR) system was used to investigate the effect of lead toxicity on metabolisms of polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) communities fed with acetic acid or glucose as their sole carbon source, respectively. Results showed that the effect of lead on substrate utilization of both PAOs and GAOs was insignificant. However, lead substantially inhibited both of phosphate release and uptake of PAOs. In high concentration of acetic acid trials, an abnormal aerobic phosphate release was observed instead of phosphate uptake and the release rate increased with increasing lead concentration. Results also showed that PAOs could normally synthesize polyhydroxybutyrate (PHB) in the anaerobic phase even though lead concentration was 40 mg L(-1). However, they could not aerobically utilize PHB normally in the presence of lead. On the other hand, GAOs could not normally metabolize polyhydroxyvalerate (PHV) in both the anaerobic and aerobic phases. PMID:21704513

  9. Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

    DOEpatents

    Rau, Gregory Hudson

    2014-07-01

    A system for forming metal hydroxide from a metal carbonate utilizes a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide.

  10. Endocytotic Uptake of Zoledronic Acid by Tubular Cells May Explain Its Renal Effects in Cancer Patients Receiving High Doses of the Compound

    PubMed Central

    Verhulst, Anja; Sun, Shuting; McKenna, Charles E.; D’Haese, Patrick C.

    2015-01-01

    Zoledronic acid, a highly potent nitrogen-containing bisphosphonate used for the treatment of pathological bone loss, is excreted unmetabolized via the kidney if not bound to the bone. In cancer patients receiving high doses of the compound renal excretion may be associated with acute tubular necrosis. The question of how zoledronic acid is internalized by renal tubular cells has not been answered until now. In the current work, using a primary human tubular cell culture system, the pathway of cellular uptake of zoledronic acid (fluorescently/radiolabeled) and its cytotoxicity were investigated. Previous studies in our laboratory have shown that this primary cell culture model consistently mimics the physiological characteristics of molecular uptake/transport of the epithelium in vivo. Zoledronic acid was found to be taken up by tubular cells via fluid-phase-endocytosis (from apical and basolateral side) as evidenced by its co-localization with dextran. Cellular uptake and the resulting intracellular level was twice as high from the apical side compared to the basolateral side. Furthermore, the intracellular zoledronic acid level was found to be dependent on the administered concentration and not saturable. Cytotoxic effects however, were only seen at higher administration doses and/or after longer incubation times. Although zoledronic acid is taken up by tubular cells, no net tubular transport could be measured. It is concluded that fluid-phase-endocytosis of zoledronic acid and cellular accumulation at high doses may be responsible for the acute tubular necrosis observed in some cancer patients receiving high doses of the compound. PMID:25756736

  11. Uptake of gamma-valerolactone--detection of gamma-hydroxyvaleric acid in human urine samples.

    PubMed

    Andresen-Streichert, H; Jungen, H; Gehl, A; Müller, A; Iwersen-Bergmann, S

    2013-05-01

    Gamma-valerolactone (GVL) is reported to be a substance that can be used as a legal substitute for gamma-hydroxybutyric acid (GHB), which is currently a controlled substance in several countries. Unlike gamma-butyrolactone and 1,4-butanediol, GVL is not metabolized to GHB, which causes the effects after uptake of these two chemicals. In the case of GVL, the lactone ring is split to gamma-hydroxyvaleric acid (GHV or 4-methyl-GHB) by a lactonase. Because of its affinity for the GHB receptor, GHV reveals similar effects to GHB, although it is less potent. Intoxications with GVL, or its use as a date rape drug, are conceivable. Despite these facts, there are no publications in the literature regarding detections of GHV in human samples. This study reports three cases, including five urine samples, in which GHV could be detected in concentrations between 3 and 5.8 mg/L. In one of these cases, a drug-facilitated sexual assault (DFSA) was assumed; four of these samples were from two people suspected of abusing GHB. The results indicate that GVL is used as an alternative to GHB and its precursors and should be taken seriously. GVL or GHV should be included in toxicological analysis, particularly in DFSA cases. More information is needed regarding the pharmacokinetics of GVL/GHV for the meaningful interpretation of positive or negative results. PMID:23486087

  12. Uptake of triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) and dicamba (3,6-dichloro-2-methoxybenzoic acid) from the apical membranes of the human intestinal Caco-2 cells.

    PubMed

    Kimura, Osamu; Tsukagoshi, Kensuke; Hayasaka, Moriaki; Endo, Tetsuya

    2012-01-01

    We investigated whether the uptake of triclopyr (3, 5, 6-trichloro-2-pyridinyloxyacetic acid) and dicamba (3,6-dichloro-2-methoxybenzoic acid) across the apical membrane of Caco-2 cells was mediated via proton-linked monocarboxylic acid transporters (MCTs). The uptake of triclopyr from the apical membranes was fast, pH-, temperature-, and concentration dependent, required metabolic energy to proceed, and was competitively inhibited by monocarboxylic acids such as benzoic acid and ferulic acid (substrates of L-lactic acid-insensitive MCTs), but not by L-lactic acid. Thus, the uptake of triclopyr in Caco-2 cells appears to be mediated mainly via L-lactic acid-insensitive MCTs. In contrast, the uptake of dicamba (a benzoic acid derivative) was slow, and it was both pH- and temperature dependent. Coincubation with ferulic acid did not decrease the uptake of dicamba, although coincubation with benzoic acid moderately decreased it. The uptake of dicamba appears to be mediated mainly via passive diffusion, which is in contrast to the uptake of benzoic acid via MCTs. We speculate that the substituted groups in dicamba may inhibit uptake via MCTs. PMID:21766207

  13. Effects of Fatty Acids on Benzo[a]pyrene Uptake and Metabolism in Human Lung Adenocarcinoma A549 Cells

    PubMed Central

    Barhoumi, Rola; Mouneimne, Youssef; Chapkin, Robert S.; Burghardt, Robert C.

    2014-01-01

    Dietary supplementation with natural chemoprotective agents is receiving considerable attention because of health benefits and lack of toxicity. In recent in vivo and in vitro experimental studies, diets rich in n-3 polyunsaturated fatty acids have been shown to provide significant anti-tumor action. In this investigation, the effects of control fatty acids (oleic acid (OA), linoleic acid (LA)) and n-3 PUFA, e.g., docosahexaenoic acid (DHA) on the uptake and metabolism of the carcinogenic polycyclic aromatic hydrocarbon, benzo[a]pyrene (BaP) was investigated in A549 cells, a human adenocarcinoma alveolar basal epithelial cell line. A549 cells activate BaP through the cytochrome P450 enzyme system to form reactive metabolites, a few of which covalently bind to DNA and proteins. Therefore, multiphoton microscopy spectral analysis combined with linear unmixing was used to identify the parent compound and BaP metabolites formed in cells, in the presence and absence of fatty acids. The relative abundance of select metabolites was associated with altered P450 activity as determined using ethoxyresorufin-O-deethylase activity in cells cultured in the presence of BSA-conjugated fatty acids. In addition, the parent compound within cellular membranes increases significantly in the presence of each of the fatty acids, with the greatest accumulation observed following DHA treatment. DHA treated cells exhibit significantly lower pyrene-like metabolites indicative of lower adducts including DNA adducts compared to control BSA, OA or LA treated cells. Further, DHA reduced the abundance of the proximate carcinogen BaP 7,8-dihydrodiol and the 3-hydroxybenzo[a]pyene metabolites compared to other treatments. The significant changes in BaP metabolites in DHA treated cells may be mediated by the effects on the physicochemical properties of the membrane known to affect enzyme activity related to phase I and phase II metabolism. In summary, DHA is a highly bioactive chemo

  14. FOLIAR LEACHING AND ROOT UPTAKE OF CA, MG, AND K IN RELATION TO ACID FOG EFFECTS ON DOUGLAS-FIR

    EPA Science Inventory

    The impact of acid fog on foliar leaching and root uptake of Ca, Mg, and K by Douglas-fir (Pseudotsuga menziesii) seedlings was examined. n a factorial experiment, 1-year old seedlings were grown in solution culture at two levels of nutrient availability (low and moderate) and ex...

  15. Composite polymeric beads containing N,N,N',N'-tetraoctyldiglycolamide for actinide ion uptake from nitric acid feeds: Batch uptake, kinetic modelling and column studies.

    PubMed

    Gujar, R B; Mohapatra, P K; Lakshmi, D Shanthana; Figoli, A

    2015-11-27

    Polyethersulphone (PES) based composite polymeric beads (CPB) containing TODGA (N,N,N',N'-tetraoctyldiglycolamide) as the extractant were prepared by conventional phase inversion technique and were tested for the uptake of actinide ions such as Am(3+), UO2(2+), Pu(4+), Np(4+) and fission product ions such as Eu(3+) and Sr(2+). The CPBs containing 2.5-10wt.% TODGA were characterized by various physical methods and their porosity, size, surface morphology, surface area and the degradation profile by thermogravimetry were analyzed. The batch uptake studies involved kinetics of metal ion sorption, uptake as a function of nitric acid concentration, kinetic modelling and adsorption isotherms and most of the studies involved the Am(3+) ions. The batch saturation sorption capacities for Eu(3+) loading at 3M HNO3 were determined to be 6.6±0.02, 9.1±0.02 and 22.3±0.04mgg(-1) of CRBs with 2.5wt.%, 5wt.% and 10wt.% TODGA, respectively. The sorption isotherm analysis with Langmuir, D-R and Freundlisch isotherms indicated chemisorption monolayer mechanism. Chromatographic studies indicated breakthrough of Eu(3+) (using a solution containing Eu carrier) after about 0.75 bed volume (3.5-4mL). Elution of the loaded Eu was carried out using 0.01M EDTA as the eluent. PMID:26518494

  16. Phosphotransferase system-mediated glucose uptake is repressed in phosphoglucoisomerase-deficient Corynebacterium glutamicum strains.

    PubMed

    Lindner, Steffen N; Petrov, Dimitar P; Hagmann, Christian T; Henrich, Alexander; Krämer, Reinhard; Eikmanns, Bernhard J; Wendisch, Volker F; Seibold, Gerd M

    2013-04-01

    Corynebacterium glutamicum is particularly known for its industrial application in the production of amino acids. Amino acid overproduction comes along with a high NADPH demand, which is covered mainly by the oxidative part of the pentose phosphate pathway (PPP). In previous studies, the complete redirection of the carbon flux toward the PPP by chromosomal inactivation of the pgi gene, encoding the phosphoglucoisomerase, has been applied for the improvement of C. glutamicum amino acid production strains, but this was accompanied by severe negative effects on the growth characteristics. To investigate these effects in a genetically defined background, we deleted the pgi gene in the type strain C. glutamicum ATCC 13032. The resulting strain, C. glutamicum Δpgi, lacked detectable phosphoglucoisomerase activity and grew poorly with glucose as the sole substrate. Apart from the already reported inhibition of the PPP by NADPH accumulation, we detected a drastic reduction of the phosphotransferase system (PTS)-mediated glucose uptake in C. glutamicum Δpgi. Furthermore, Northern blot analyses revealed that expression of ptsG, which encodes the glucose-specific EII permease of the PTS, was abolished in this mutant. Applying our findings, we optimized l-lysine production in the model strain C. glutamicum DM1729 by deletion of pgi and overexpression of plasmid-encoded ptsG. l-Lysine yields and productivity with C. glutamicum Δpgi(pBB1-ptsG) were significantly higher than those with C. glutamicum Δpgi(pBB1). These results show that ptsG overexpression is required to overcome the repressed activity of PTS-mediated glucose uptake in pgi-deficient C. glutamicum strains, thus enabling efficient as well as fast l-lysine production. PMID:23396334

  17. Characterization of cesium uptake mediated by a potassium transport system of bacteria in a soil conditioner.

    PubMed

    Zhang, Pengyao; Idota, Yoko; Yano, Kentaro; Negishi, Masayuki; Kawabata, Hideaki; Arakawa, Hiroshi; Morimoto, Kaori; Tsuji, Akira; Ogihara, Takuo

    2014-01-01

    We found that bacteria in a commercial soil conditioner sold in Ishinomaki, Miyagi, exhibited concentrative and saturable cesium ion (Cs(+)) uptake in the natural range of pH and temperature. The concentration of intracellular Cs(+) could be condensed at least a few times higher compared with the outside medium of the cells. This uptake appeared to be mediated by a K(+) transport system, since Cs(+) uptake was dose-dependently inhibited by potassium ion (K(+)). Eadie-Hofstee plot analysis indicated that the Cs(+) uptake involved a single saturable process. The maximum uptake amount (Jmax) was the same in the presence and absence of K(+), suggesting that Cs(+) and K(+) uptakes were competitive with respect to each other. These bacteria might be useful for bioremediation of cesium-contaminated soil. PMID:24694606

  18. Ursodeoxycholic and deoxycholic acids: Differential effects on intestinal Ca(2+) uptake, apoptosis and autophagy of rat intestine.

    PubMed

    Rodríguez, Valeria A; Rivoira, María A; Pérez, Adriana del V; Marchionatti, Ana M; Tolosa de Talamoni, Nori G

    2016-02-01

    The aim of this work was to study the effect of sodium deoxycholate (NaDOC) and ursodeoxycholic acid (UDCA) on Ca(2+) uptake by enterocytes and the underlying mechanisms. Rats were divided into four groups: a) controls, b) treated with NaDOC, c) treated with UDCA d) treated with NaDOC and UDCA. Ca(2+) uptake was studied in enterocytes with different degrees of maturation. Apoptosis, autophagy and NO content and iNOS protein expression were evaluated. NaDOC decreased and UDCA increased Ca(2+) uptake only in mature enterocytes. The enhancement of protein expression of Fas, FasL, caspase-8 and caspase-3 activity by NaDOC indicates triggering of the apoptotic extrinsic pathway, which was blocked by UDCA. NO content and iNOS protein expression were enhanced by NaDOC, and avoided by UDCA. The increment of acidic vesicular organelles and LC3 II produced by NaDOC was also prevented by UDCA. In conclusion, the inhibitory effects of NaDOC on intestinal Ca(2+) absorption occur by decreasing the Ca(2+) uptake by mature enterocytes. NaDOC triggers apoptosis and autophagy, in part as a result of nitrosative stress. In contrast, UDCA increases the Ca(2+) uptake by mature enterocytes, and in combination with NaDOC acts as an antiapoptotic and antiautophagic agent normalizing the transcellular Ca(2+) pathway. PMID:26707246

  19. Gallium-67 uptake by the thyroid associated with progressive systemic sclerosis

    SciTech Connect

    Sjoberg, R.J.; Blue, P.W.; Kidd, G.S.

    1989-01-01

    Although thyroidal uptake of gallium-67 has been described in several thyroid disorders, gallium-67 scanning is not commonly used in the evaluation of thyroid disease. Thyroidal gallium-67 uptake has been reported to occur frequently with subacute thyroiditis, anaplastic thyroid carcinoma, and thyroid lymphoma, and occasionally with Hashimoto's thyroiditis and follicular thyroid carcinoma. A patient is described with progressive systemic sclerosis who, while being scanned for possible active pulmonary involvement, was found incidentally to have abnormal gallium-67 uptake only in the thyroid gland. Fine needle aspiration cytology of the thyroid revealed Hashimoto's thyroiditis. Although Hashimoto's thyroiditis occurs with increased frequency in patients with progressive systemic sclerosis, thyroidal uptake of gallium-67 associated with progressive systemic sclerosis has not, to our knowledge, been previously described. Since aggressive thyroid malignancies frequently are imaged by gallium-67 scintigraphy, fine needle aspiration cytology of the thyroid often is essential in the evaluation of thyroidal gallium-67 uptake.

  20. Evaluation of cellular uptake and intracellular trafficking as determining factors of gene expression for amino acid-substituted gemini surfactant-based DNA nanoparticles

    PubMed Central

    2012-01-01

    Background Gene transfer using non-viral vectors offers a non-immunogenic and safe method of gene delivery. Cellular uptake and intracellular trafficking of the nanoparticles can impact on the transfection efficiency of these vectors. Therefore, understanding the physicochemical properties that may influence the cellular uptake and the intracellular trafficking can aid the design of more efficient non-viral gene delivery systems. Recently, we developed novel amino acid-substituted gemini surfactants that showed higher transfection efficiency than their parent compound. In this study, we evaluated the mechanism of cellular uptake of the plasmid/gemini surfactant/helper lipid nanoparticles and their effect on the transfection efficiency. Results Nanoparticles were incubated with Sf 1 Ep cells in the presence of different endocytic inhibitors and gene expression (interferon-γ) was measured using ELISA. Clathrin-mediated and caveolae-mediated uptake were found to be equally contributing to cellular internalization of both P/12-7NH-12/L (parent gemini surfactant) and P/12-7NGK-12/L (amino acid-substituted gemini surfactant) nanoparticles. The plasmid and the helper lipid were fluorescently tagged to track the nanoparticles inside the cells, using confocal laser scanning microscopy. Transmission electron microscopy images showed that the P/12-7NGK-12/L particles were cylindrical while the P/12-7NH-12/L particles were spherical which may influence the cellular uptake behaviour of these particles. Dye exclusion assay and pH-titration of the nanoparticles suggested that high buffering capacity, pH-dependent increase in particle size and balanced DNA binding properties may be contributing to a more efficient endosomal escape of P/12-7NGK-12/L compared to the P/12-7NH-12/L nanoparticles, leading to higher gene expression. Conclusion Amino-acid substitution in the spacer of gemini surfactant did not alter the cellular uptake pathway, showing similar pattern to the

  1. Organ-specific dietary fatty acid uptake in humans using positron emission tomography coupled to computed tomography.

    PubMed

    Labbé, Sébastien M; Grenier-Larouche, Thomas; Croteau, Etienne; Normand-Lauzière, François; Frisch, Frédérique; Ouellet, René; Guérin, Brigitte; Turcotte, Eric E; Carpentier, André C

    2011-03-01

    A noninvasive method to determine postprandial fatty acid tissue partition may elucidate the link between excess dietary fat and type 2 diabetes. We hypothesized that the positron-emitting fatty acid analog 14(R,S)-[(18)F]fluoro-6-thia-heptadecanoic acid ((18)FTHA) administered orally during a meal would be incorporated into chylomicron triglycerides, allowing determination of interorgan dietary fatty acid uptake. We administered (18)FTHA orally at the beginning of a standard liquid meal ingested in nine healthy men. There was no significant (18)FTHA uptake in the portal vein and the liver during the 1st hour. Whole body PET/CT acquisition revealed early appearance of (18)FTHA in the distal thoracic duct, reaching a peak at time 240 min. (18)FTHA mean standard uptake value increased progressively in the liver, heart, quadriceps, and subcutaneous and visceral adipose tissues between time 60 and 240 min. Most circulating (18)F activity between time 0 and 360 min was recovered into chylomicron triglycerides. Using Triton WR-1339 treatment in rats that received (18)FTHA by gavage, we confirmed that >90% of this tracer reached the circulation as triglycerides. This novel noninvasive method to determine tissue dietary fatty acid distribution in humans should prove useful in the study of the mechanisms leading to lipotoxicity. PMID:21098737

  2. Docosahexaenoic acid in neural signaling systems.

    PubMed

    Crawford, Michael A

    2006-01-01

    Docosahexaenoic acid has been conserved in neural signalling systems in the cephalopods, fish, amphibian, reptiles, birds, mammals, primates and humans. This extreme conservation, despite wide genomic changes over 500 million years, testifies to a uniqueness of this molecule in the brain. The brain selectively incorporates docosahexaenoic acid and its rate of incorporation into the developing brain has been shown to be greater than ten times more efficient than its synthesis from the omega 3 fatty acids of land plant origin. Data has now been published demonstrating a significant influence of dietary omega 3 fatty acids on neural gene expression. As docosahexaenoic acid is the only omega 3 fatty acid in the brain, it is likely that it is the ligand involved. The selective uptake, requirement for function and stimulation of gene expression would have conferred an advantage to a primate which separated from the chimpanzees in the forests and woodlands and sought a different ecological niche. In view of the paucity of docosahexaenoic acid in the land food chain it is likely that the advantage would have been gained from a lacustrine or marine coastal habitat with access to food rich in docosahexaenoic acid and the accessory micronutrients, such as iodine, zinc, copper, manganese and selenium, of importance in brain development and protection against peroxidation. Land agricultural development has, in recent time, come to dominate the human food chain. The decline in use and availability of aquatic resources is not considered important by Langdon (2006) as he considers the resource was not needed for human evolution and can be replaced from the terrestrial food chain. This notion is not supported by the biochemistry nor the molecular biology. He misses the point that the shoreline hypothesis is not just dependent on docosahexaenoic acid but also on the other accessory nutrients specifically required by the brain. Moreover he neglects the basic principle of Darwinian

  3. Short-chain fatty acid (SCFA) uptake into Caco-2 cells by a pH-dependent and carrier mediated transport mechanism.

    PubMed

    Stein, J; Zores, M; Schröder, O

    2000-06-01

    The short-chain fatty acids, acetate, propionate, and butyrate, are the most abundant organic anions in the human colon. SCFA play a pivotal role in maintaining homeostasis in the colon. Particularly butyrate induces cell differentiation and regulates growth and proliferation of colonic mucosal epithelial cells, whereas it reduces the growth rate of colorectal cancer cell. Previous studies by several groups, including our own, using isolated membrane vesicles have demonstrated that the uptake of butyrate is at least in part mediated by a non-electrogenic SCFA-/HCO3- antiporter. The purpose of the present study was to determine (1) whether Caco-2 cells could serve as an experimental model to assess the mechanisms of SCFA transport, and (2) whether monocarboxlate transporters could play a role in SCFA transport in these cells. Caco-2 cells were found to transport 14C-butyrate in a concentration and time dependent manner. The uptake was sodium independent, but was stimulated by lowering extracellular pH. The uptake of 500 microM butyrate was reduced by 49.6% +/- 3.3% in the presence of propionate and by 57.2% +/- 4.8% in the presence of 10 mM L-lactate. The addition of 1 mM alpha-cyano-4-hydroxycinnamate and phloretin, both known to be potent inhibitors of MCT1, decreased the uptake of 500 microM 14C-butyrate by 59.4% +/- 4.1% and 48.9% +/- 3.3%, respectively, whereas similar concentrations of DIDS did not have any effect. These data suggest that the uptake of butyrate in Caco-2 cells occurs via a carrier mediated transport system specific for monocarboxylic acids, which is in accordance with characteristics of the MCT 1. PMID:10918994

  4. Carrier-Mediated Uptake of 1-(Malonylamino)cyclopropane-1-Carboxylic Acid in Vacuoles Isolated from Catharanthus roseus Cells 1

    PubMed Central

    Bouzayen, Mondher; Latché, Alain; Pech, Jean-Claude; Marigo, Gérard

    1989-01-01

    The uptake of 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC), the conjugated form of the ethylene precursor, into vacuoles isolated from Catharanthus roseus cells has been studied by silicone layer floatation filtering. The transport across the tonoplast of MACC is stimulated fourfold by 5 millimolar MgATP, has a Km of about 2 millimolar, an optimum pH around 7, and an optimum temperature at 30°C. Several effectors known to inhibit ATPase (N,N′-dicyclohexylcarbodiimide) and to collapse the transtonoplastic H+ electrochemical gradient (carbonylcyanide m-chlorophenylhydrazone, gramicidin, and benzylamine) all reduced MACC uptake. Abolishing the membrane potential with SCN− and valinomycin also greatly inhibited MACC transport. Our data demonstrate that MACC accumulates in the vacuole against a concentration gradient by means of a proton motive force generated by a tonoplastic ATPase. The involvement of a protein carrier is suggested by the strong inhibition of uptake by compounds known to block SH—, OH—, and NH2— groups. MACC uptake is antagonized competitively by malonyl-d-tryptophan, indicating that the carrier also accepts malonyl-d-amino acids. Neither the moities of these compounds taken separately [1-aminocyclopropane-1-carboxylic acid, malonate, d-tryptophan or d-phenylalanine] nor malate act as inhibitors of MACC transport. The absence of inhibition of malate uptake by MACC suggests that MACC and malate are taken up by two different carriers. We propose that the carrier identified here plays an important physiological role in withdrawing from the cytosol MACC and malonyl-d-amino acids generated under stress conditions. PMID:16667182

  5. Anti-glioma activity and the mechanism of cellular uptake of asiatic acid-loaded solid lipid nanoparticles.

    PubMed

    Garanti, Tanem; Stasik, Aneta; Burrow, Andrea Julie; Alhnan, Mohamed A; Wan, Ka-Wai

    2016-03-16

    Asiatic acid (AA), a pentacyclic triterpene found in Centella Asiatica, has shown neuroprotective and anti-cancer activity against glioma. However, owing to its poor aqueous solubility, effective delivery and absorption across biological barriers, in particular the blood brain barrier (BBB), are challenging. Solid lipid nanoparticles (SLNs) have shown a promising potential as a drug delivery system to carry lipophilic drugs across the BBB, a major obstacle in brain cancer therapy. Nevertheless, limited information is available about the cytotoxic mechanisms of nano-lipidic carriers with AA on normal and glioma cells. This study assessed the anti-cancer efficacy of AA-loaded SLNs against glioblastoma and their cellular uptake mechanism in comparison with SVG P12 (human foetal glial) cells. SLNs were systematically investigated for three different solid lipids; glyceryl monostearate (MS), glyceryl distearate (DS) and glyceryl tristearate (TS). The non-drug containing MS-SLNs (E-MS-SLNs) did not show any apparent toxicity towards normal SVG P12 cells, whilst the AA-loaded MS-SLNs (AA-MS-SLNs) displayed a more favourable drug release profile and higher cytotoxicity towards U87 MG cells. Therefore, MS-SLNs were chosen for further in vitro studies. Cytotoxicity studies of SLNs (± AA) were performed using MTT assay where AA-SLNs showed significantly higher cytotoxicity towards U87 MG cells than SVG P12 normal cells, as confirmed by flow cell cytometry. Cellular uptake of SLNs also appeared to be preferentially facilitated by energy-dependent endocytosis as evidenced by fluorescence imaging and flow cell cytometry. Using the Annexin V-PI double staining technique, it was found that these AA-MS-SLNs displayed concentration-dependent apoptotic activity on glioma cells, which further confirms the potential of exploiting these AA-loaded MS-SLNs for brain cancer therapy. PMID:26775062

  6. Differential effects of eicosapentaenoic and docosahexaenoic acids upon oxidant-stimulated release and uptake of arachidonic acid in human lymphoma U937 cells.

    PubMed

    Obajimi, Oluwakemi; Black, Kenneth D; MacDonald, Donald J; Boyle, Rose M; Glen, Iain; Ross, Brian M

    2005-08-01

    The use of n-3 polyunsaturated fatty acids, as found in fish-oil derived dietary supplements, as anti-inflammatory agents is supported by a variety of biochemical and physiological data. Recent studies investigating the therapeutic potential of long chain (>C20) n-3 fatty acids in mental illness have lead to the conclusion, however, that not all n-3 fatty acid types are equally efficacious. In particular eicosapentaeoic acid (EPA) appears to possess antidepressant and antipsychotic activity, while docosahexaenoic acid (DHA) does not, an effect suggested to be due to a differential ability to antagonize arachidonic acid (AA)-dependent cell signalling. In this study, we examine the effect of EPA and DHA supplementation upon uptake and release of arachidonic acid stimulated by tert-butyl hydroperoxide/Fe2+ in U937 cells. Oxidant-stimulated 3H-AA release from cells was enhanced by pre-treatment with EPA, DHA and AA, but not stearic or oleic acids for 18 days, with the order of effect magnitude being EPA > DHA = AA. Supplementation of cells for 1 day gave qualitatively similar results, although the effect magnitude was smaller. To determine whether enhanced release was due to decreased reuptake of AA, cells were cultured in the presence of 10 microM fatty acids. Pre-treatment of cells with EPA, and to a lesser extent AA, but not DHA, inhibited uptake of 3H-AA measured subsequent to the removal of unesterified fatty acids. This study suggests that, in U937 cells, EPA can alter the rate of uptake and release of AA from phospholipids in an exposure time-dependent manner, whereas DHA has no or little effect. Our results predict that EPA will have a more pronounced effect upon AA-dependent processes compared to DHA, and suggests that the relative amounts of EPA and DHA in fish oil supplements may modify their biochemical, and potentially, behavioural effects. PMID:15967385

  7. Molecular and cellular characterisation of the zinc uptake (Znu) system of Nostoc punctiforme.

    PubMed

    Hudek, Lee; Pearson, Leanne A; Michalczyk, Agnes; Neilan, Brett A; Ackland, M Leigh

    2013-11-01

    Metal homoeostasis in cyanobacteria is based on uptake and export systems that are controlled by their own regulators. This study characterises the zinc uptake (Znu) system in Nostoc punctiforme. The system was found to comprise of three subunits in an ACB operon: a Zn(2+)-binding protein (ZnuA18), a transmembrane domain (ZnuB) and an ATPase (ZnuC). These proteins are encoded within the znu operon regulated by a zinc uptake transcription repressor (Zur). Interestingly, a second Zn(2+)-binding protein (ZnuA08) was also identified at a distal genomic location. Interactions between components of the ZnuACB system were investigated using knockouts of the individual genes. The znuA08(-), znuA18(-), znuB(-) and znuC(-) mutants displayed overall reduced znuACB transcript levels, suggesting that all system components are required for normal expression of znu genes. Zinc uptake assays in the Zn(2+)-binding protein mutant strains showed that the disruption of znuA18 had a greater negative effect on zinc uptake than disruption of znuA08. Complementation studies in Escherichia coli indicated that both znuA08 and znuA18 were able to restore zinc uptake in a znuA(-) mutant, with znuA18 permitting the highest zinc uptake rate. The N. punctiforme zur was also able to complement the E. coli zur(-) mutant. PMID:23710564

  8. Plasma membrane phospholipase A2 controls hepatocellular fatty acid uptake and is responsive to pharmacological modulation: implications for nonalcoholic steatohepatitis.

    PubMed

    Stremmel, Wolfgang; Staffer, Simone; Wannhoff, Andreas; Pathil, Anita; Chamulitrat, Walee

    2014-07-01

    Excess hepatic fat accumulation leads to nonalcoholic steatohepatitis (NASH), a serious threat to health for which no effective treatment is available. However, the mechanism responsible for fatty acid uptake by hepatocytes remains unclear. Using the human hepatocyte-derived tumor cell line HepG2, we found that fatty acid influx is mediated by a heterotetrameric plasma membrane protein complex consisting of plasma membrane fatty acid-binding protein, caveolin-1, CD36, and calcium-independent membrane phospholipase A2 (iPLA2β). Blocking iPLA2β with the bile acid-phospholipid conjugate ursodeoxycholate-lysophosphatidylethanolamide (UDCA-LPE) caused the dissociation of the complex, thereby inhibiting fatty acid influx (IC50 47 μM), and suppressed the synthesis of all subunits through a reduction in lysophosphatidylcholine from 8.0 to 3.5 μmol/mg of protein and corresponding depletion of phosphorylated c-Jun N-terminal kinase. These findings were substantiated by an observed 56.5% decrease in fatty acid influx in isolated hepatocytes derived from iPLA2β-knockout mice. Moreover, steatosis and inflammation were abrogated by UDCA-LPE treatment in a cellular model of NASH. Thus, iPLA2β acts as an upstream checkpoint for mechanisms that regulate fatty acid uptake, and its inhibition by UDCA-LPE qualifies this nontoxic compound as a therapeutic candidate for the treatment of NASH.-Stremmel, W., Staffer, S., Wannhoff, A., Pathil, A., Chamulitrat, W. Plasma membrane phospholipase A2 controls hepatocellular fatty acid uptake and is responsive to pharmacological modulation: implications for nonalcoholic steatohepatitis. PMID:24719358

  9. Similarity in microbial amino acid uptake in surface waters of the North and South Atlantic (sub-)tropical gyres

    NASA Astrophysics Data System (ADS)

    Hill, Polly G.; Mary, Isabelle; Purdie, Duncan A.; Zubkov, Mikhail V.

    2011-12-01

    The Earth’s most extensive biomes - the oceanic subtropical gyres - are considered to be expanding with current surface ocean warming. Although it is well established that microbial communities control gyre biogeochemistry, comparisons of their metabolic activities between gyres are limited. In order to estimate metabolic activities including production of microbial communities, the uptake rates of amino acids leucine, methionine and tyrosine at ambient concentrations were estimated in surface waters of the Atlantic Ocean using radioisotopically labelled tracers. Data were acquired during six research cruises covering main oceanic provinces herein termed: North and South Atlantic Gyres, Bermuda Atlantic Time-series Study site (BATS), Equatorial region, and Mauritanian Upwelling (off Cape Blanc). Data were divided between provinces, the extents of which were identified by ocean colour data, in order to achieve provincial mean uptake rates. Leucine and methionine uptake rates did not differ between sampling periods, and were comparable between the North and South subtropical gyres. Furthermore, variation in uptake rates measured throughout the two oligotrophic gyres, where sampling covered ∼4 × 10 6 km 2, was considerably lower than that measured within the Mauritanian Upwelling and Equatorial regions, and even at the BATS site. Tyrosine was generally the slowest of the amino acids to be taken up, however, it was assimilated faster than methionine within the Mauritanian Upwelling region. Thus, we propose that one value for leucine (12.6 ± 3.2 pmol L -1 h -1) and methionine (10.0 ± 3.3 pmol L -1 h -1) uptake could be applied to the oligotrophic subtropical gyres of the Atlantic Ocean. However, with the significantly lower uptake rates observed at the BATS site, we would not advise extrapolation to the Sargasso Sea.

  10. Tracking amino acid's uptake into the protozoan Acanthamoeba castellanii by stable-isotope labelling and Raman spectral imaging

    NASA Astrophysics Data System (ADS)

    Naemat, Abida; Elsheikha, Hany M.; Notingher, Ioan

    2016-04-01

    The capacity of pathogens to acquire nutrients from their host cells is one of the most fundamental aspects of infection biology. Hence, measuring the patterns of nutrients' uptake by pathogens is essential for understanding the interactions of pathogens with eukaryotic host cells. In this study, we optimized a technique that allows fast and non-destructive measurement of the amino acid Phenylalanine (Phe) acquired by the trophozoite stage of the protozoan Acanthamoeba castellanii (A. castellanii) as they engage with individual human retinal pigment epithelial cells (ARPE-19). ARPE-19 host cells were pre-saturated with Deuterated Phe (L-Phe(D8)) to replace the native substrate Phe (L-Phe). The uptake of L-Phe(D8) by A. castellanii trophozoites was measured by Raman microspectroscopy. This approach allowed us to characterize the uptake patterns of this essential amino acid into A. castellanii trophozoites at a single cell level. At 24 hours post infection (PI) A. castellanii trophozoites are capable of salvaging L-Phe(D8) from host cells. The uptake pattern was time-dependent during the first 24 hours of infection and complete substitution with L-Phe(D8) in all parasites was detected at 48 hours PI. On the other hand, isolated A. castellanii trachyzoites (grown without host cells) did not show significant uptake for L-Phe(D8) from the media; only achieved an uptake ratio of 16-18% of L-Phe(D8) from the culture medium after 24 hours. These findings demonstrate the potential of combining Raman microspectroscopy and stable isotope labelling approaches to elucidate the role of metabolism in mediating A. castellanii interaction with host cells.

  11. Arsenic uptake by Lemna minor in hydroponic system.

    PubMed

    Goswami, Chandrima; Majumder, Arunabha; Misra, Amal Kanti; Bandyopadhyay, Kaushik

    2014-01-01

    Arsenic is hazardous and causes several ill effects on human beings. Phytoremediation is the use of aquatic plants for the removal of toxic pollutants from external media. In the present research work, the removal efficiency as well as the arsenic uptake capacity of duckweed Lemna minor has been studied. Arsenic concentration in water samples and plant biomass were determined by AAS. The relative growth factor of Lemna minor was determined. The duckweed had potential to remove as well as uptake arsenic from the aqueous medium. Maximum removal of more than 70% arsenic was achieved atinitial concentration of 0.5 mg/1 arsenic on 15th day of experimental period of 22 days. Removal percentage was found to decrease with the increase in initial concentration. From BCF value, Lemna minor was found to be a hyperaccumulator of arsenic at initial concentration of 0.5 mg/L, such that accumulation decreased with increase in initial arsenic concentration. PMID:24933913

  12. Effects of Lipids on in Vitro Release and Cellular Uptake of β-Carotene in Nanoemulsion-Based Delivery Systems.

    PubMed

    Yi, Jiang; Zhong, Fang; Zhang, Yuzhu; Yokoyama, Wallace; Zhao, Liqing

    2015-12-23

    β-Carotene (BC) nanoemulsions were successfully prepared by microfluidization. BC micellarization was significantly affected by bile salts and pancreatin concentration. Positive and linear correlation was observed between BC release and bile salts concentration. Pancreatin facilitated BC's release in simulated digestion. Compared to the control (bulk oil) (4.6%), nanoemulsion delivery systems significantly improved the micellarization of BC (70.9%). The amount of BC partitioned into micelles was positively proportional to the length of carrier oils. Unsaturated fatty acid (UFA)-rich oils were better than saturated fatty acid (SFA)-rich oils in transferring BC (p < 0.05). No significant difference was observed between monounsaturated fatty acid (MUFA)-rich oils and polyunsaturated fatty acid (PUFA)-rich oils (p > 0.05). A positive and linear relationship between the degree of lipolysis and the release of BC in vitro digestion was observed. Bile salts showed cytotoxicity to Caco-2 cells below 20 times dilution. BC uptake by Caco-2 cells was not affected by fatty acid (FA) compositions in micelles, but BC uptake was proportional to its concentration in the diluted micelle fraction. The results obtained are beneficial to encapsulate and deliver BC or other bioactive lipophilic carotenoids in a wide range of commercial products. PMID:26629789

  13. The routes and kinetics of trichloroacetic acid uptake and elimination in Sitka spruce ( Picea sitchensis) saplings via atmospheric deposition pathways

    NASA Astrophysics Data System (ADS)

    Heal, M. R.; Dickey, C. A.; Cape, J. N.; Heal, K. V.

    A major flux of trichloroacetic acid (TCA) to forests is via wet deposition, but the transfer of TCA into tree foliage may occur by an above- or below-ground pathway. To investigate the routes and kinetics of TCA uptake, two groups of 10 Sitka spruce saplings (with an equivalent number of controls) were exposed to a single application of 200 μg TCA in solution, either to the soil only, or sprayed as a mist to the foliage only. The needle foliage was subsequently analysed regularly for TCA for 3 months during the growing season. Significant uptake into current year ( C) needles was observed from both routes just a few days after application, providing direct evidence of an above-ground uptake route. Uptake of TCA was also observed in the previous year needle class ( C+1). Kinetic modelling of the data indicated that the half-life for within-needle elimination (during the growing season) was ˜50±30 days. Most of the applied TCA appeared to be degraded before uptake, either in the soil, or externally on the sapling foliage.

  14. Iron uptake in Pseudomonas aeruginosa mediated by N-(2,3-dihydroxybenzoyl)-L-serine and 2,3-dihydroxybenzoic acid.

    PubMed

    Screen, J; Moya, E; Blagbrough, I S; Smith, A W

    1995-03-15

    Pseudomonas aeruginosa is known to have an inducible uptake system for the enterobacterial siderophore enterobactin. In this work we have examined iron transport mediated by the biosynthetic precursor 2,3-dihydroxybenzoic acid and N-(2,3-dihydroxybenzoyl)-L-serine, a breakdown product of enterobactin. Iron complexed with 2,3-dihydroxybenzoyl-L-serine was transported into P. aeruginosa IA1 via a transport system which is energy-dependent and iron-repressible. The rate of transport was not altered by growing the cells in the presence of either pyoverdin or pyochelin, which have been shown previously to induce transport via that system. Growth of the cells in the presence of enterobactin did cause an increase in the rate of transport, indicating that the complex can be transported by the inducible enterobactin uptake system, but also that a separate system must exist. In contrast, transport of iron complexed with 2,3-dihydroxybenzoic acid was neither iron-repressible nor strongly energy-dependent, from which we conclude that there must be a novel mode of transport not characteristic of iron-siderophore transport systems. PMID:7737477

  15. Warming decreased and grazing increased plant uptake of amino acids in an alpine meadow.

    PubMed

    Ma, Shuang; Zhu, Xiaoxue; Zhang, Jing; Zhang, Lirong; Che, Rongxiao; Wang, Fang; Liu, Hanke; Niu, Haishan; Wang, Shiping; Cui, Xiaoyong

    2015-09-01

    Organic nitrogen (N) uptake by plants has been recognized as a significant component of terrestrial N cycle. Several studies indicated that plants have the ability to switch their preference between inorganic and organic forms of N in diverse environments; however, research on plant community response in organic nitrogen uptake to warming and grazing is scarce. Here, we demonstrated that organic N uptake by an alpine plant community decreased under warming with (13)C-(15)N-enriched glycine addition method. After 6 years of treatment, warming decreased plant organic N uptake by 37% as compared to control treatment. Under the condition of grazing, warming reduced plant organic N uptake by 44%. Grazing alone significantly increased organic N absorption by 15%, whereas under warming condition grazing did not affect organic N uptake by the Kobresia humilis community on Tibetan Plateau. Besides, soil NO 3-N content explained more than 70% of the variability observed in glycine uptake, and C:N ratio in soil dissolved organic matter remarkably increased under warming treatment. These results suggested warming promoted soil microbial activity and dissolved organic N mineralization. Grazing stimulated organic N uptake by plants, which counteracted the effect of warming. PMID:26442646

  16. VERSATILE GAS UPTAKE INHALATION SYSTEM USED IN PHARMACOKINETIC AN METABOLIC STUDIES OF VOLATILE ORGANIC COMPOUNDS

    EPA Science Inventory

    This paper describes an automated gas uptake system for pharmacokinetic research with volatiles, designed to operate within the parameters maintained during conventional whole body inhalation exposures, according to the Good Laboratory Practices (GLP) guidelines. he benefit is to...

  17. Characterization of the Rhizobium (Sinorhizobium) meliloti high- and low-affinity phosphate uptake systems.

    PubMed Central

    Voegele, R T; Bardin, S; Finan, T M

    1997-01-01

    Genetic studies have suggested that Rhizobium (Sinorhizobium) meliloti contains two distinct phosphate (Pi) transport systems, encoded by the phoCDET genes and the orfA-pit genes, respectively. Here we present data which show that the ABC-type PhoCDET system has a high affinity for Pi (Km, 0.2 microM) and that Pi uptake by this system is severely inhibited by phosphonates. This high-affinity uptake system was induced under Pi-limiting conditions and was repressed in the presence of excess Pi. Uptake via the OrfA-Pit system was examined in (i) a phoC mutant which showed increased expression of the orfA-pit genes as a result of a promoter-up mutation and (ii) a phoB mutant (PhoB is required for phoCDET expression). Pi uptake in both strains exhibited saturation kinetics (Km, 1 to 2 microM) and was not inhibited by phosphonates. This uptake system was active in wild-type cells grown with excess Pi and appeared to be repressed when the cells were starved for Pi. Thus, our biochemical data show that the OrfA-Pit and PhoCDET uptake systems are differentially expressed depending on the state of the cell with respect to phosphate availability. PMID:9393684

  18. Isoprene Epoxydiols as Precursors to Secondary Organic Aerosol Formation: Acid-Catalyzed Reactive Uptake Studies with Authentic Compounds

    PubMed Central

    Lin, Ying-Hsuan; Zhang, Zhenfa; Docherty, Kenneth S.; Zhang, Haofei; Budisulistiorini, Sri Hapsari; Rubitschun, Caitlin L.; Shaw, Stephanie L.; Knipping, Eladio M.; Edgerton, Eric S.; Kleindienst, Tadeusz E.; Gold, Avram; Surratt, Jason D.

    2011-01-01

    Isoprene epoxydiols (IEPOX), formed from the photooxidation of isoprene under low-NOx conditions, have recently been proposed as precursors of secondary organic aerosol (SOA) on the basis of mass spectrometric evidence. In the present study, IEPOX isomers were synthesized in high purity (> 99%) to investigate their potential to form SOA via reactive uptake in a series of controlled dark chamber studies followed by reaction product analyses. IEPOX-derived SOA was substantially observed only in the presence of acidic aerosols, with conservative lower-bound yields of 4.7–6.4% for β-IEPOX and 3.4–5.5% for δ-IEPOX, providing direct evidence for IEPOX isomers as precursors to isoprene SOA. These chamber studies demonstrate that IEPOX uptake explains the formation of known isoprene SOA tracers found in ambient aerosols, including 2-methyltetrols, C5-alkene triols, dimers, and IEPOX-derived organosulfates. Additionally, we show reactive uptake on the acidified sulfate aerosols supports a previously unreported acid-catalyzed intramolecular rearrangement of IEPOX to cis- and trans-3-methyltetrahydrofuran-3,4-diols (3-MeTHF-3,4-diols) in the particle phase. Analysis of these novel tracer compounds by aerosol mass spectrometry (AMS) suggests that they contribute to a unique factor resolved from positive matrix factorization (PMF) of AMS organic aerosol spectra collected from low-NOx, isoprene-dominated regions influenced by the presence of acidic aerosols. PMID:22103348

  19. Nitrogen nutrition in the cyanobacterium Nostoc ANTH, a symbiotic isolate from Anthoceros: uptake and assimilation of inorganic-n and amino acids.

    PubMed

    Bhattacharya, Jyotirmoy; Singh, Arvind Kumar; Rai, Amar Nath

    2002-06-01

    Amino acid uptake and utilization of various nitrogen sources (amino acids, nitrite, nitrate and ammonia) were studied in Nostoc ANTH and i ts mu tant (Het(-)Nif(-)) isolate defective in heterocyst formation and N2-fixation. Both parent and its mutant grew at the expense of glutamine, asparagine and arginine as a source of fixed-nitrogen. Growth was better in glutamine-and asparagine-media as compared to that in arginine media. Glutamine and asparagine repressed heterocyst formation, N2-fixation and nitrate reduction in Nostoc ANTH, but arginine did so only partially. The poor growth in arginine-medium was not due to poor uptake rates, since the uptake rates were not significantly different from those for glutamine or asparagine. The glutamine synthetase activity remained unaffected during cultivation in media containing any one of the three amino acids tested. The uptake of amino acids was substrate-inducible, energy-dependent and required de novo protein synthesis. Nitrate and ammonium repressed ammonium uptake, but did not repress uptake of amino acids. In N2-medium (BG-11(0)), the uptake of ammonium and amino acids in the mutant was significantly higher than its parent strain. This was apparently due to nitrogen limitation since the mutant was unable to fix N2 and the growth medium lacked combined-N. PMID:22905386

  20. Sulfate metabolism. I. Sulfate uptake and redistribution of acid rain sulfate by edible plants

    SciTech Connect

    Dallam, R.D.

    1987-03-23

    Sulfur is the major component of polluted air in industrialized societies. Atmospheric sulfur is converted to sulfuric acid through a series of chemical reactions which can eventually reenter many ecosystems. When edible plants are grown in soils containing varying amounts of sulfate, the roots take up and transport inorganic sulfate to the stems and leaves. The sulfate taken up by the roots and the amount transported to the stem and leaves was found to be a function of the concentration of sulfate in the soil. Inorganic sulfate taken up by a corn plant seedling can be rapidly converted to organic sulfate by the root system. Nine days after one of a pair of pea plants was inoculated with artificial acid rain sulfate (dilute H/sub 2//sup 35/SO/sub 4/) it was found that the sulfate was translocated not only in the inoculated plant, but also to the uninoculated pea plant in the same container. Also, when the leaves of a mature potato plant were inoculated with artificial acid rain sulfate it was found that the sulfate was translocated into the edible potatoes. Fractionation of the potatoes showed that most of the sulfate was water soluble of which 30% was inorganic sulfate and 70% was in the form of organic sulfur. One third of the non-water soluble translocated acid rain sulfate was equally divided between lipid and non-lipid organic sulfur of the potato. 9 references, 2 figures, 5 tables.

  1. Characteristics and osmoregulatory roles of uptake systems for proline and glycine betaine in Lactococcus lactis.

    PubMed Central

    Molenaar, D; Hagting, A; Alkema, H; Driessen, A J; Konings, W N

    1993-01-01

    Lactococcus lactis subsp. lactis ML3 contains high pools of proline or betaine when grown under conditions of high osmotic strength. These pools are created by specific transport systems. A high-affinity uptake system for glycine betaine (betaine) with a Km of 1.5 microM is expressed constitutively. The activity of this system is not stimulated by high osmolarities of the growth or assay medium but varies strongly with the medium pH. A low-affinity proline uptake system (Km, > 5 mM) is expressed at high levels only in chemically defined medium (CDM) with high osmolarity. This transport system is also stimulated by high osmolarity. The expression of this proline uptake system is repressed in rich broth with low or high osmolarity and in CDM with low osmolarity. The accumulated proline can be exchanged for betaine. Proline uptake is also effectively inhibited by betaine (Ki of between 50 and 100 microM). The proline transport system therefore probably also transports betaine. The inhibition of proline transport by betaine results in low proline pools in cells grown in high-osmotic-strength, betaine-containing CDM. The energy and pH dependency and the influence of ionophores on the activity of both transport systems suggest that these systems are not proton motive force driven. At low osmolarities, proline uptake is low but significant. This low proline uptake is also inhibited by betaine, although to a lesser extent than in cells grown in high-osmotic-strength CDM. These data indicate that proline uptake in L. lactis is enzyme mediated and is not dependent on passive diffusion, as was previously believed. PMID:8366030

  2. The differential hepatic uptake of chylomicron remnants of different fatty acid composition is not mediated by hepatic lipase.

    PubMed

    Lambert, M S; Avella, M A; Berhane, Y; Shervill, E; Botham, K M

    2001-05-01

    The hypothesis that hepatic lipase mediates the differential hepatic uptake of chylomicron remnants of different fatty acid composition, demonstrated in previous work from our laboratory, was tested by investigating the effect of antibodies to the enzyme on the uptake of remnants enriched with saturated or n-3 polyunsaturated fatty acids by the perfused rat liver. After perfusion of rat livers with polyclonal antibodies to rat hepatic lipase raised in rabbits or with rabbit non-immune serum for 15 min, [3H]oleate-labelled chylomicron remnants, derived from chylomicrons of rats given a bolus of either palm (rich in saturated fatty acids) oil or fish (rich in n-3 polyunsaturated fatty acids) oil, were added. The disappearance of radioactivity from the perfusate during 120 min and its recovery in the liver at the end of the experiments were then measured. Although the rabbit anti-rat hepatic lipase antiserum was shown to inhibit hepatic lipase activity by up to 90%, and to bind extensively to hepatic sinusoidal surfaces when added to the perfusate, radioactivity from remnants of chylomicrons from rats given a bolus of fish oil as compared with palm oil disappeared from the perfusate and appeared in the liver more rapidly in the presence both the antiserum and the non-immune serum, and the differences between the uptake of the two types of remnants were similar. We conclude, therefore, that differential interaction with hepatic lipase is not responsible for the differences in the rate of removal of chylomicron remnants of different fatty acid composition from the blood. PMID:11348572

  3. The role of acid-sensing ion channels in epithelial Na+ uptake in adult zebrafish (Danio rerio).

    PubMed

    Dymowska, Agnieszka K; Boyle, David; Schultz, Aaron G; Goss, Greg G

    2015-04-15

    Acid-sensing ion channels (ASICs) are epithelial Na(+) channels gated by external H(+). Recently, it has been demonstrated that ASICs play a role in Na(+) uptake in freshwater rainbow trout. Here, we investigate the potential involvement of ASICs in Na(+) transport in another freshwater fish species, the zebrafish (Danio rerio). Using molecular and histological techniques we found that asic genes and the ASIC4.2 protein are expressed in the gill of adult zebrafish. Immunohistochemistry revealed that mitochondrion-rich cells positive for ASIC4.2 do not co-localize with Na(+)/K(+)-ATPase-rich cells, but co-localize with cells expressing vacuolar-type H(+)-ATPase. Furthermore, pharmacological inhibitors of ASIC and Na(+)/H(+)-exchanger significantly reduced uptake of Na(+) in adult zebrafish exposed to low-Na(+) media, but did not cause the same response in individuals exposed to ultra-low-Na(+) water. Our results suggest that in adult zebrafish ASICs play a role in branchial Na(+) uptake in media with low Na(+) concentrations and that mechanisms used for Na(+) uptake by zebrafish may depend on the Na(+) concentration in the acclimation medium. PMID:25722005

  4. Tartaric Acid-based Amphiphilic Macromolecules with Ether Linkages Exhibit Enhanced Repression of Oxidized Low Density Lipoprotein Uptake

    PubMed Central

    Abdelhamid, Dalia; Zhang, Yingue; Lewis, Daniel R.; Moghe, Prabhas V.; Welsh, William J.; Uhrich, Kathryn E.

    2015-01-01

    Cardiovascular disease initiates with the atherogenic cascade of scavenger receptor- (SR-) mediated oxidized low-density lipoprotein (oxLDL) uptake. Resulting foam cell formation leads to lipid-rich lesions within arteries. We designed amphiphilic macromolecules (AMs) to inhibit these processes by competitively blocking oxLDL uptake via SRs, potentially arresting atherosclerotic development. In this study, we investigated the impact of replacing ester linkages with ether linkages in the AM hydrophobic domain. We hypothesized that ether linkages would impart flexibility for orientation to improve binding to SR binding pockets, enhancing anti-atherogenic activity. A series of tartaric acid-based AMs with varying hydrophobic chain lengths and conjugation chemistries were synthesized, characterized, and evaluated for bioactivity. 3-D conformations of AMs in aqueous conditions may have significant effects on anti-atherogenic potency and were simulated by molecular modeling. Notably, ether-linked AMs exhibited significantly higher levels of inhibition of oxLDL uptake than their corresponding ester analogues, indicating a dominant effect of linkage flexibility on pharmacological activity. The degradation stability was also enhanced for ether-linked AMs. These studies further suggested that alkyl chain length (i.e., relative hydrophobicity), conformation (i.e., orientation), and chemical stability play a critical role in modulating oxLDL uptake, and guide the design of innovative cardiovascular therapies. PMID:25890704

  5. Tissue specific uptake and elimination of perfluoroalkyl acids (PFAAs) in adult rainbow trout (Oncorhynchus mykiss) after dietary exposure.

    PubMed

    Falk, Sandy; Failing, Klaus; Georgii, Sebastian; Brunn, Hubertus; Stahl, Thorsten

    2015-06-01

    Tissue specific uptake and elimination of perfluoroalkyl acids (PFAAs) were studied in rainbow trout (Oncorhynchus mykiss). Adult trout were exposed to perfluorobutane sulfonic acid (PFBS), perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA) via food over a time period of 28d. In the following 28-d depuration period the fish were fed PFAA-free food. At defined sampling times four animals were removed from the experimental tank, euthanized and dissected. Muscle, liver, kidneys, gills, blood, skin and carcass were examined individually. At the end of the accumulation phase between 0.63% (PFOA) and 15.5% (PFOS) of the absolute, applied quantity of PFAAs was recovered in the whole fish. The main target organ was the liver with recovery rates between 0.11% (PFBS) and 4.01% (PFOS) of the total amount of ingested PFAAs. Perfluoroalkyl sulfonic acids were taken up more readily and had longer estimated elimination half-lives than perfluoroalkyl carboxylic acids of the same chain length. The longest estimated elimination half-lives were found to be for PFOS between 8.4d in muscle tissue and 20.4d in the liver and for PFNA between 8.2d in the blood and 11.6d in the liver. PMID:25022474

  6. Gamma-aminobutyric acid esters. 1. Synthesis, brain uptake, and pharmacological studies of aliphatic and steroid esters of gamma-aminobutyric acid

    SciTech Connect

    Shashoua, V.E.; Jacob, J.N.; Ridge, R.; Campbell, A.; Baldessarini, R.J.

    1984-05-01

    Labeled and unlabeled aliphatic and steroid esters of gamma-amino(U-/sup 14/C)butyric acid (GABA) were synthesized and tested for their capacity to penetrate the blood-brain barrier and for evidence of central neuropharmacological activity in rodents. The uptake of the labeled 9,12,15-octadecatrienyl (linolenyl), 3-cholesteryl, 1-butyl, and the 9-fluoro-11 beta,17-dihydroxy-16 alpha-methyl-3,20-dioxopregna -1,4-dien-21-yl (dexamethasone) esters of GABA into mouse brain increased 2-, 25-, 74-, and 81-fold over GABA, respectively. The cholesteryl ester of GABA depressed the general motor activity of mice and rats in a dose-dependent manner, whereas the 1-butyl, linolenyl, and dexamethasone esters were inactive by this test. Studies of the rates of hydrolysis, GABA receptor binding capacity, and octanol/water partition coefficients indicated that pharmacological activity of the esters after entry into the central nervous system (CNS) was dependent on their capacity to release GABA by enzymatic hydrolysis and their lipid solubility.

  7. Increased Hepatic Fatty Acids Uptake and Oxidation by LRPPRC-Driven Oxidative Phosphorylation Reduces Blood Lipid Levels

    PubMed Central

    Lei, Shi; Sun, Run-zhu; Wang, Di; Gong, Mei-zhen; Su, Xiang-ping; Yi, Fei; Peng, Zheng-wu

    2016-01-01

    Hyperlipidemia is one of the major risk factors of atherosclerosis and other cardiovascular diseases. This study aimed to investigate the impact of leucine rich pentatricopeptide repeat containing protein (LRPPRC)-driven hepatic oxidative phoshorylation on blood lipid levels. The hepatic LRPPRC level was modulated by liver-specific transgenic or adeno-associated virus 8 carried shRNA targeting Lrpprc (aav-shLrpprc). Mice were fed with a high fat diet to induce obesity. Gene expression was analyzed by quantitative real-time PCR and / or western blot. The hepatic ATP level, hepatic and serum lipids contents, and mitochondria oxidative phosphorylation (OxPhos) complex activities were measured using specific assay kits. The uptake and oxidation of fatty acid by hepatocytes were assessed using 14C-palmitate. LRPPRC regulated the expression of genes encoded by mitochondrial genome but not those by nuclear genome involved in mitochondria biogenesis, OxPhos, and lipid metabolism. Increased OxPhos in liver mediated by LRPPRC resulted in the increase of hepatic ATP level. Lrpprc promoted palmitate uptake and oxidation by hypatocytes. The hepatic and serum triglyceride and total cholesterol levels were inversely associated with the hepatic LRPPRC level. These data demonstrated that LRPPRC-driven hepatic OxPhos could promote fatty acids uptake and oxidation by hepatocytes and reduce both hepatic and circulating triglyceride and cholesterol levels. PMID:27462273

  8. Increased Hepatic Fatty Acids Uptake and Oxidation by LRPPRC-Driven Oxidative Phosphorylation Reduces Blood Lipid Levels.

    PubMed

    Lei, Shi; Sun, Run-Zhu; Wang, Di; Gong, Mei-Zhen; Su, Xiang-Ping; Yi, Fei; Peng, Zheng-Wu

    2016-01-01

    Hyperlipidemia is one of the major risk factors of atherosclerosis and other cardiovascular diseases. This study aimed to investigate the impact of leucine rich pentatricopeptide repeat containing protein (LRPPRC)-driven hepatic oxidative phoshorylation on blood lipid levels. The hepatic LRPPRC level was modulated by liver-specific transgenic or adeno-associated virus 8 carried shRNA targeting Lrpprc (aav-shLrpprc). Mice were fed with a high fat diet to induce obesity. Gene expression was analyzed by quantitative real-time PCR and / or western blot. The hepatic ATP level, hepatic and serum lipids contents, and mitochondria oxidative phosphorylation (OxPhos) complex activities were measured using specific assay kits. The uptake and oxidation of fatty acid by hepatocytes were assessed using (14)C-palmitate. LRPPRC regulated the expression of genes encoded by mitochondrial genome but not those by nuclear genome involved in mitochondria biogenesis, OxPhos, and lipid metabolism. Increased OxPhos in liver mediated by LRPPRC resulted in the increase of hepatic ATP level. Lrpprc promoted palmitate uptake and oxidation by hypatocytes. The hepatic and serum triglyceride and total cholesterol levels were inversely associated with the hepatic LRPPRC level. These data demonstrated that LRPPRC-driven hepatic OxPhos could promote fatty acids uptake and oxidation by hepatocytes and reduce both hepatic and circulating triglyceride and cholesterol levels. PMID:27462273

  9. Organosulfate formation during the uptake of pinonaldehyde on acidic sulfate aerosols

    NASA Astrophysics Data System (ADS)

    Liggio, John; Li, Shao-Meng

    2006-07-01

    Organosulfates are observed in studies of pinonaldehyde reactions with acidic sulfate aerosols using aerosol mass spectrometry, during which a significant fraction of the pinonaldehyde reaction products were found to consist of organosulfate compounds that account for 6-51% of the initial SO4= mass. Resultant aerosol mass spectra were consistent with proposed sulfate ester mechanisms, which likely form stable products. The existence of organosulfates was also confirmed in studies of the reaction system in bulk solution. The formation of organosulfates suggests that conventional inorganic SO4= chemical analysis may underestimate total SO4= mass in ambient aerosols.

  10. Potential use of carbon-11 labeled alpha-aminoisobutyric acid (AIB) as an in vivo tracer of amino acid uptake in differing metabolic states

    SciTech Connect

    Conti, P.S.; Starnes, H.F.; Brennan, M.F.

    1986-05-01

    AIB has been used as a model amino acid for the evaluation of alanine-preferring amino acid transport. Hormonal factors and starvation alter the tissue distribution of amino acids, particularly in liver and muscle. With positron emission tomography and labeling of biochemical tracers with C-11, (t1/2=20.4 min), it is now possible to study amino acid kinetics in vivo using external imaging. In order to investigate the utility of C-11 AIB as an in vivo tracer of altered tissue metabolism, C-14 AIB was studied in groups of rats with either streptozotocin-induced diabetes, insulin-induced hypoglycemia or starvation. The data suggest an increased amino acid uptake in liver in starvation, an increased uptake in muscle in response to insulin and associated hypoglycemia and decreased transport in muscle in starvation, as seen by other investigators. These results suggest that C-11 AIB may be useful as an in vivo monitor of metabolic changes in body tissues.

  11. Contributions of five secondary metal uptake systems to metal homeostasis of Cupriavidus metallidurans CH34.

    PubMed

    Kirsten, Andreas; Herzberg, Martin; Voigt, Alexander; Seravalli, Javier; Grass, Gregor; Scherer, Judith; Nies, Dietrich H

    2011-09-01

    Cupriavidus metallidurans is adapted to high concentrations of transition metal cations and is a model system for studying metal homeostasis in difficult environments. The elemental composition of C. metallidurans cells cultivated under various conditions was determined, revealing the ability of the bacterium to shield homeostasis of one essential metal from the toxic action of another. The contribution of metal uptake systems to this ability was studied. C. metallidurans contains three CorA members of the metal inorganic transport (MIT) protein family of putative magnesium uptake systems, ZupT of the ZRT/IRT protein, or ZIP, family, and PitA, which imports metal phosphate complexes. Expression of the genes for all these transporters was regulated by zinc availability, as shown by reporter gene fusions. While expression of zupT was upregulated under conditions of zinc starvation, expression of the other genes was downregulated at high zinc concentrations. Only corA(1) expression was influenced by magnesium starvation. Deletion mutants were constructed to characterize the contribution of each system to transition metal import. This identified ZupT as the main zinc uptake system under conditions of low zinc availability, CorA(1) as the main secondary magnesium uptake system, and CorA(2) and CorA(3) as backup systems for metal cation import. PitA may function as a cation-phosphate uptake system, the main supplier of divalent metal cations and phosphate in phosphate-rich environments. Thus, metal homeostasis in C. metallidurans is achieved by highly redundant metal uptake systems, which have only minimal cation selectivity and are in combination with efflux systems that "worry later" about surplus cations. PMID:21742896

  12. Design, synthesis and SAR studies of GABA uptake inhibitors derived from 2-substituted pyrrolidine-2-yl-acetic acids.

    PubMed

    Steffan, Tobias; Renukappa-Gutke, Thejavathi; Höfner, Georg; Wanner, Klaus T

    2015-03-15

    In this paper, we disclose the design and synthesis of a series of 2-substituted pyrrolidine-2-yl-acetic acid as core structures and the N-arylalkyl derivatives thereof as potential GABA transport inhibitors. The 2-position in the side chain of pyrrolidine-2-yl-acetic acid derivatives was substituted with alkyl, hydroxy and amino groups to modulate the activity and selectivity to mGAT1 and mGAT4 proteins. SAR studies of the compounds performed for the four mouse GABA transporter proteins (mGAT1-mGAT4) implied significant potencies and subtype selectivities for 2-hydroxy-2-pyrrolidine-2-yl-acetic acid derivatives. The racemate rac-(u)-13c exhibited the highest potency (pIC50 5.67) at and selectivity for mGAT1 in GABA uptake assays. In fact, the potency of rac-(u)-13c at hGAT-1 (pIC50 6.14) was even higher than its potency at mGAT1. These uptake results for rac-(u)-13c are in line with the binding affinities to the aforesaid proteins mGAT1 (pKi 6.99) and hGAT-1 (pKi 7.18) determined by MS Binding Assay based on NO711 as marker quantified by LC-ESI-MS-MS analysis. Interestingly, the 2-hydroxy-2-pyrrolidine-2-yl-acetic acid rac-(u)-13d containing 2-{[tris(4-methoxyphenyl)]methoxy} ethyl group at the nitrogen atom of the pyrrolidine ring showed high potency at mGAT4 and a comparatively better selectivity for this protein (>15 against mGAT3) than the well known mGAT4 uptake inhibitor (S)-SNAP-5114. PMID:25698617

  13. Role of Iron Uptake Systems in Pseudomonas aeruginosa Virulence and Airway Infection.

    PubMed

    Minandri, Fabrizia; Imperi, Francesco; Frangipani, Emanuela; Bonchi, Carlo; Visaggio, Daniela; Facchini, Marcella; Pasquali, Paolo; Bragonzi, Alessandra; Visca, Paolo

    2016-08-01

    Pseudomonas aeruginosa is a leading cause of hospital-acquired pneumonia and chronic lung infections in cystic fibrosis patients. Iron is essential for bacterial growth, and P. aeruginosa expresses multiple iron uptake systems, whose role in lung infection deserves further investigation. P. aeruginosa Fe(3+) uptake systems include the pyoverdine and pyochelin siderophores and two systems for heme uptake, all of which are dependent on the TonB energy transducer. P. aeruginosa also has the FeoB transporter for Fe(2+) acquisition. To assess the roles of individual iron uptake systems in P. aeruginosa lung infection, single and double deletion mutants were generated in P. aeruginosa PAO1 and characterized in vitro, using iron-poor media and human serum, and in vivo, using a mouse model of lung infection. The iron uptake-null mutant (tonB1 feoB) and the Fe(3+) transport mutant (tonB1) did not grow aerobically under low-iron conditions and were avirulent in the mouse model. Conversely, the wild type and the feoB, hasR phuR (heme uptake), and pchD (pyochelin) mutants grew in vitro and caused 60 to 90% mortality in mice. The pyoverdine mutant (pvdA) and the siderophore-null mutant (pvdA pchD) grew aerobically in iron-poor media but not in human serum, and they caused low mortality in mice (10 to 20%). To differentiate the roles of pyoverdine in iron uptake and virulence regulation, a pvdA fpvR double mutant defective in pyoverdine production but expressing wild-type levels of pyoverdine-regulated virulence factors was generated. Deletion of fpvR in the pvdA background partially restored the lethal phenotype, indicating that pyoverdine contributes to the pathogenesis of P. aeruginosa lung infection by combining iron transport and virulence-inducing capabilities. PMID:27271740

  14. Photosynthetic mixed culture polyhydroxyalkanoate (PHA) production from individual and mixed volatile fatty acids (VFAs): substrate preferences and co-substrate uptake.

    PubMed

    Fradinho, J C; Oehmen, A; Reis, M A M

    2014-09-20

    This work studied the effect of the substrate feeding composition on the polyhydroxyalkanoate (PHA) accumulation capacity of an acetate enriched photosynthetic mixed culture (PMC). From the six tested organic acids - malate, citrate, lactate, acetate, propionate and butyrate - only the three volatile fatty acids (VFAs) enabled PHA production, with acetate and butyrate leading to polyhydroxybutyrate (PHB) formation and propionate leading to a HB:HV copolymer with a 51% fraction of hydroxyvalerate (HV). Also, results showed an acceleration of butyrate and propionate consumption when fed in the presence of acetate, suggesting that the latter can act as a co-substrate for butyrate and propionate uptake. Furthermore, results suggest that some PMC bacterial groups present a substrate preference for butyrate in relation to acetate and propionate. These findings indicate the possibility of feeding the PMC with cheap VFA rich fermented wastes, leading to a more cost-effective and environmentally sustainable PHA production system. PMID:24915131

  15. Intracellular Uptake and Trafficking of Difluoroboron Dibenzoylmethane-Poly(lactic acid) Nanoparticles in HeLa Cells

    PubMed Central

    Contreras, Janette; Xie, Jiansong; Chen, Yin Jie; Pei, Hua; Zhang, Guoqing; Fraser, Cassandra L.; Hamm-Alvarez, Sarah F.

    2010-01-01

    In this study, nanoparticles based on difluoroboron dibenzoylmethane-poly(lactic acid) (BF2dbmPLA) are prepared. Polylactic acid or polylactide is a commonly used degradable polymer, while the boron dye possesses a large extinction coefficient, high emission quantum yield, 2-photon absorption, and sensitivity to the surrounding environment. BF2dbmPLA exhibits molecular weight-dependent emission properties, and can be formulated as stable nanoparticles, suggesting that its unique optical properties may be useful in multiple contexts for probing intracellular environments. Here we show that BF2dbmPLA nanoparticles are internalized into cultured HeLa cells by endocytosis, and that within the cellular milieu they retain their fluorescence properties. BF2dbmPLA nanoparticles are photostable, resisting laser-induced photobleaching under conditions that destroy the fluorescence of a common photostable probe, LysoTracker™ blue. Their endocytosis is also lipid raft-dependent, as evidenced by their significant co-localization with cholera toxin B subunit in membrane compartments after uptake, and their sensitivity of uptake to methyl-β-cyclodextrin. Additionally, BF2dbmPLA nanoparticle endocytosis utilizes microtubules and actin filaments. Internalized BF2dbmPLA nanoparticles do not accumulate in acidic late endosomes and lysosomes, but within a perinuclear non-lysosomal compartment. These findings demonstrate the feasibility of using novel BF2dbmPLA nanoparticles exhibiting diverse emission properties for in situ, live cell imaging, and suggest that their endogenous uptake occurs through a lipid-raft dependent endocytosis mechanism. PMID:20420413

  16. An Inexpensive Electrode and Cell for Measurement of Oxygen Uptake in Chemical and Biochemical Systems.

    ERIC Educational Resources Information Center

    Brunet, Juan E.; And Others

    1983-01-01

    The continuous measurement of oxygen consumption in an enzymatic reaction is a frequent experimental fact and extremely important in the enzymatic activity of oxygenase. An electrochemical system, based on a polarographic method, has been developed to monitor the oxygen uptake. The system developed and electrode used are described. (JN)

  17. Acid-sensing ion channels are involved in epithelial Na+ uptake in the rainbow trout Oncorhynchus mykiss

    PubMed Central

    Dymowska, Agnieszka K.; Schultz, Aaron G.; Blair, Salvatore D.; Chamot, Danuta

    2014-01-01

    A role for acid-sensing ion channels (ASICs) to serve as epithelial channels for Na+ uptake by the gill of freshwater rainbow trout was investigated. We found that the ASIC inhibitors 4′,6-diamidino-2-phenylindole and diminazene decreased Na+ uptake in adult rainbow trout in a dose-dependent manner, with IC50 values of 0.12 and 0.96 μM, respectively. Furthermore, we cloned the trout ASIC1 and ASIC4 homologs and demonstrated that they are expressed differentially in the tissues of the rainbow trout, including gills and isolated mitochondrion-rich cells. Immunohistochemical analysis using custom-made anti-zASIC4.2 antibody and the Na+-K+-ATPase (α5-subunit) antibody demonstrated that the trout ASIC localizes to Na+/K+-ATPase-rich cells in the gill. Moreover, three-dimensional rendering of confocal micrographs demonstrated that ASIC is found in the apical region of mitochondrion-rich cells. We present a revised model whereby ASIC4 is proposed as one mechanism for Na+ uptake from dilute freshwater in the gill of rainbow trout. PMID:24898589

  18. Foliar leaching and root uptake of Ca, Mg and K in relation to acid fog effects on Douglas Fir

    SciTech Connect

    Turner, D.P.; Tingey, D.T.

    1990-01-01

    The impact of acid fog on foliar leaching and root uptake of Ca, Mg, and K by Douglas-fir (Pseudotsuga menziesii) seedlings was examined. In a factorial experiment, 1-year old seedlings were grown in a solution culture at two levels of nutrient availability (low and moderate) and exposed twice a week (4 hr per event) for 12 weeks to fog at pH 5.6 or pH 3.1. Throughfall enrichment of Ca, Mg and K was determined from drip collectors at the base of each seedling and root uptake rates for trees under the moderate nutrient regime were evaluated by monitoring nutrient solution depletion. Throughfall enrichment was higher in the pH 3.1 fog than the pH 5.6 fog but much of the enrichment appeared to be wash off of precipitate from previous fogs. The amounts of nutrients coming off of the foliage with the low pH fog were small relative to the daily uptake rates. Foliar concentrations of K and Mg at the end of the exposures were lower under the low nutrient regime but were not affected by fog pH. Comparisons of wax weight and examinations of epicuticular wax by electron microscopy did not indicate a significant impact from exposure to the low pH fog.

  19. Docosahexaenoic acid enhances iron uptake by modulating iron transporters and accelerates apoptotic death in PC12 cells.

    PubMed

    Schonfeld, Eldi; Yasharel, Ilanit; Yavin, Ephraim; Brand, Annette

    2007-10-01

    The effect of docosahexaenoic acid (DHA; 22:6 n-3) on Fe(2+)-mediated and/or H(2)O(2)-mediated oxidative stress (OS) was investigated in a PC12 pheochromocytoma cell line in the presence or absence of 50 ng/ml nerve growth factor (NGF). DHA-supplemented cells showed enhanced Fe(2+)-induced cell damage as evident by increased lipid peroxides formation (10-fold) and reduced neutral red (NR) dye uptake in a NGF-independent fashion. DHA caused a nearly 10-fold increase in free iron uptake in NGF-treated cells and doubled iron uptake in nondifferentiated cells. DHA-enrichment induced an elevation in the transferrin receptor protein in the nondifferentiated cells whereas NGF-treatment led to a substantial increase in the ubiquitous divalent metal ion transporter 1 (DMT-1) as detected by mRNA levels using qRT-PCR. The mechanism of action of DHA to accelerate cell death may be associated with the externalization of amino-phosphoglycerides (PG) species of which, increased ethanolamine plasmalogen levels, may be essential for cell rescue as noted in NGF-treated PC12 cells. PMID:17551831

  20. Nitrate sensing and uptake in Arabidopsis are enhanced by ABI2, a phosphatase inactivated by the stress hormone abscisic acid.

    PubMed

    Léran, Sophie; Edel, Kai H; Pervent, Marjorie; Hashimoto, Kenji; Corratgé-Faillie, Claire; Offenborn, Jan Niklas; Tillard, Pascal; Gojon, Alain; Kudla, Jörg; Lacombe, Benoît

    2015-05-01

    Living organisms sense and respond to changes in nutrient availability to cope with diverse environmental conditions. Nitrate (NO3-) is the main source of nitrogen for plants and is a major component in fertilizer. Unraveling the molecular basis of nitrate sensing and regulation of nitrate uptake should enable the development of strategies to increase the efficiency of nitrogen use and maximize nitrate uptake by plants, which would aid in reducing nitrate pollution. NPF6.3 (also known as NRT1.1), which functions as a nitrate sensor and transporter; the kinase CIPK23; and the calcium sensor CBL9 form a complex that is crucial for nitrate sensing in Arabidopsis thaliana. We identified two additional components that regulate nitrate transport, sensing, and signaling: the calcium sensor CBL1 and protein phosphatase 2C family member ABI2, which is inhibited by the stress-response hormone abscisic acid. Bimolecular fluorescence complementation assays and in vitro kinase assays revealed that ABI2 interacted with and dephosphorylated CIPK23 and CBL1. Coexpression studies in Xenopus oocytes and analysis of plants deficient in ABI2 indicated that ABI2 enhanced NPF6.3-dependent nitrate transport, nitrate sensing, and nitrate signaling. These findings suggest that ABI2 may functionally link stress-regulated control of growth and nitrate uptake and utilization, which are energy-expensive processes. PMID:25943353

  1. Acid-sensing ion channels are involved in epithelial Na+ uptake in the rainbow trout Oncorhynchus mykiss.

    PubMed

    Dymowska, Agnieszka K; Schultz, Aaron G; Blair, Salvatore D; Chamot, Danuta; Goss, Greg G

    2014-08-01

    A role for acid-sensing ion channels (ASICs) to serve as epithelial channels for Na(+) uptake by the gill of freshwater rainbow trout was investigated. We found that the ASIC inhibitors 4',6-diamidino-2-phenylindole and diminazene decreased Na(+) uptake in adult rainbow trout in a dose-dependent manner, with IC50 values of 0.12 and 0.96 μM, respectively. Furthermore, we cloned the trout ASIC1 and ASIC4 homologs and demonstrated that they are expressed differentially in the tissues of the rainbow trout, including gills and isolated mitochondrion-rich cells. Immunohistochemical analysis using custom-made anti-zASIC4.2 antibody and the Na(+)-K(+)-ATPase (α5-subunit) antibody demonstrated that the trout ASIC localizes to Na(+)/K(+)-ATPase-rich cells in the gill. Moreover, three-dimensional rendering of confocal micrographs demonstrated that ASIC is found in the apical region of mitochondrion-rich cells. We present a revised model whereby ASIC4 is proposed as one mechanism for Na(+) uptake from dilute freshwater in the gill of rainbow trout. PMID:24898589

  2. K+ uptake in plant roots. The systems involved, their regulation and parallels in other organisms.

    PubMed

    Nieves-Cordones, Manuel; Alemán, Fernando; Martínez, Vicente; Rubio, Francisco

    2014-05-15

    Potassium (K(+)) is an essential macronutrient for plants. It is taken into the plant by the transport systems present in the plasma membranes of root epidermal and cortical cells. The identity of these systems and their regulation is beginning to be understood and the systems of K(+) transport in the model species Arabidopsis thaliana remain far better characterized than in any other plant species. Roots can activate different K(+) uptake systems to adapt to their environment, important to a sessile organism that needs to cope with a highly variable environment. The mechanisms of K(+) acquisition in the model species A. thaliana are the best characterized at the molecular level so far. According to the current model, non-selective channels are probably the main pathways for K(+) uptake at high concentrations (>10mM), while at intermediate concentrations (1mM), the inward rectifying channel AKT1 dominates K(+) uptake. Under lower concentrations of external K(+) (100μM), AKT1 channels, together with the high-affinity K(+) uptake system HAK5 contribute to K(+) acquisition, and at extremely low concentrations (<10μM) the only system capable of taking up K(+) is HAK5. Depending on the species the high-affinity system has been named HAK5 or HAK1, but in all cases it fulfills the same functions. The activation of these systems as a function of the K(+) availability is achieved by different mechanisms that include phosphorylation of AKT1 or induction of HAK5 transcription. Some of the characteristics of the systems for root K(+) uptake are shared by other organisms, whilst others are specific to plants. This indicates that some crucial properties of the ancestral of K(+) transport systems have been conserved through evolution while others have diverged among different kingdoms. PMID:24810767

  3. Uptake measurements of acetic acid on ice and nitric acid-doped thin ice films over upper troposphere/lower stratosphere temperatures.

    PubMed

    Romanias, Manolis N; Zogka, Antonia G; Papadimitriou, Vassileios C; Papagiannakopoulos, Panos

    2012-03-01

    The adsorption of gaseous acetic acid (CH(3)C(O)OH) on thin ice films and on ice doped with nitric acid (1.96 and 7.69 wt %) was investigated over upper troposphere and lower stratosphere (UT/LS) temperatures (198-208 K), and at low gas concentrations. Experiments were performed in a Knudsen flow reactor coupled to a quadrupole mass spectrometer. The initial uptake coefficients, γ(0), on thin ice films or HNO(3)-doped ice films were measured at low surface coverage. In all cases, γ(0) showed an inverse temperature dependence, and for pure thin ice films, it was given by the expression γ(0)(T) = (4.73 ± 1.13) × 10(-17) exp[(6496 ± 1798)/T]; the quoted errors are the 2σ precision of the linear fit, and the estimated systematic uncertainties are included in the pre-exponential factor. The inverse temperature dependence suggests that the adsorption process occurs via the formation of an intermediate precursor state. Uptakes were well represented by the Langmuir adsorption model, and the saturation surface coverage, N(max), on pure thin ice films was (2.11 ± 0.16) × 10(14) molecules cm(-2), independent of temperature in the range 198-206 K. Light nitration (1.96 and 7.69 wt %) of ice films resulted in more efficient CH(3)C(O)OH uptakes and larger N(max) values that may be attributed to in-bulk diffusion or change in nature of the gas-ice surface interaction. Finally, it was estimated that the rate of adsorption of acetic acid on high-density cirrus clouds in the UT/LS is fast, and this is reflected in the short atmospheric lifetimes (2-8 min) of acetic acid; however, the extent of this uptake is minor resulting in at most a 5% removal of acetic acid in UT/LS cirrus clouds. PMID:22313232

  4. Influence of different acid and alkaline cleaning agents on the effects of irrigation of synthetic dairy factory effluent on soil quality, ryegrass growth and nutrient uptake.

    PubMed

    Liu, Y-Y; Haynes, R J

    2013-01-01

    The aim of this study was to examine the effects of replacement of phosphoric acid with nitric or acetic acid, and replacement of NaOH with KOH, as cleaning agents in dairy factories, on the effects that irrigation of dairy factory effluent (DFE) has on the soil-plant system. A 16-week greenhouse study was carried out in which the effects of addition of synthetic dairy factory effluent containing (a) milk residues alone or milk residues plus (b) H(3)PO(4)/NaOH, (c) H(3)PO(4)/HNO(3)/NaOH or (d) CH(3)COOH/KOH, on soil's chemical, physical and microbial properties and perennial ryegrass growth and nutrient uptake were investigated. The cumulative effect of DFE addition was to increase exchangeable Na, K, Ca, Mg, exchangeable sodium percentage, microbial biomass C and N and basal respiration in the soil. Dry matter yields of ryegrass were increased by additions of DFE other than that containing CH(3)COOH. Plant uptake of P, Ca and Mg was in the same order as their inputs in DFE but for Na; inputs were an order of magnitude greater than plant uptake. Replacement of NaOH by KOH resulted in increased accumulation of exchangeable K. The effects of added NaOH and KOH on promoting breakdown of soil aggregates during wet sieving (and formation of a < 0.25 mm size class) were similar. Replacement of H(2)PO(4) by HNO(3) is a viable but CH(3)COOH appears to have detrimental effects on plant growth. Replacement of NaOH by KOH lowers the likelihood of phytotoxic effects of Na, but K and Na have similar effects on disaggregation. PMID:22707204

  5. Transfection of L6 myoblasts with adipocyte fatty acid-binding protein cDNA does not affect fatty acid uptake but disturbs lipid metabolism and fusion.

    PubMed Central

    Prinsen, C F; Veerkamp, J H

    1998-01-01

    We studied the involvement of fatty acid-binding protein (FABP) in growth, differentiation and fatty acid metabolism of muscle cells by lipofection of rat L6 myoblasts with rat heart (H) FABP cDNA or with rat adipocyte (A) FABP cDNA in a eukaryotic expression vector which contained a puromycin acetyltransferase cassette. Stable transfectants showed integration into the genome for all constructs and type-specific overexpression at the mRNA and protein level for the clones with H-FABP and A-FABP cDNA constructs. The rate of proliferation of myoblasts transfected with rat A-FABP cDNA was 2-fold higher compared with all other transfected cells. In addition, these myoblasts showed disturbed fusion and differentiation, as assessed by morphological examination and creatine kinase activity. Uptake rates of palmitate were equal for all clone types, in spite of different FABP content and composition. Palmitate oxidation over a 3 h period was similar in all clones from growth medium. After being cultured in differentiation medium, mock- and H-FABP-cDNA-transfected cells showed a lower fatty acid-oxidation rate, in contrast with A-FABP-cDNA-transfected clones. The ratio of [14C]palmitic acid incorporation into phosphatidylcholine and phosphatidylethanolamine of A-FABP-cDNA-transfected clones changed in the opposite direction in differentiation medium from that of mock- and H-FABP-cDNA-transfected clones. In conclusion, transfection of L6 myoblasts with A-FABP cDNA does not affect H-FABP content and fatty acid uptake, but changes fatty acid metabolism. The latter changes may be related to the observed fusion defect. PMID:9425108

  6. Understanding Groundwater Uptake by Phreatophytic Vegetation using a System Dynamics Modeling Approach

    NASA Astrophysics Data System (ADS)

    Gou, S.; Miller, G. R.

    2012-12-01

    Modeling root water uptake provides a powerful tool for illustrating the tight linkage of phreatophytic vegetation with spatial and temporal soil water content variation and groundwater level fluctuations. In this study, we develop a new model framework to simulate root water uptake of phreatophytic vegetation using system dynamics approach. The model simulates root water uptake from saturated and unsaturated zones driven by the potential gradients along the groundwater-soil-plant-atmosphere continuum (GSPAC). It incorporates variable soil and plant hydraulic conductivity properties. A new water stress function is introduced; it considers the influence of both soil water and groundwater on phreatophyte water stress. This function is based on the "vulnerability curve" theory that the loss of hydraulic conductance along the soil-plant pathway limits the plant's capability of extracting and transporting water for transpiration. The model calculates energy balance (water potential changes) and water balance (water content changes) in both soil and plant media simultaneously and has the ability to simulate hydraulic redistribution. This model is applied to simulate water uptake of Quercus douglasii (blue oak) in a California savanna; this species has previously been identified as an obligate phreatophyte. The model results show good agreement with the measured ET, soil moisture, and leaf water potential data. The model indicates that the primary water source of blue oak switches from soil water in wet season to groundwater in dry season. In June, July and August, the average groundwater uptake rate is 13 mm/month, which contributes over 90% of dry season transpiration. During the extreme dry period, the rhizosphere resistance increases significantly and becomes the dominant resistance along the GSPAC. Under such conditions, uptake of groundwater becomes more thermodynamically favorable than uptake of soil water. In addition, the model predicts that during the dry season

  7. A two-component high-affinity nitrate uptake system in barley.

    PubMed

    Tong, Yiping; Zhou, Jing-Jiang; Li, Zhensheng; Miller, Anthony J

    2005-02-01

    The analysis of genome databases for many different plants has identified a group of genes that are related to one part of a two-component nitrate transport system found in algae. Earlier work using mutants and heterologous expression has shown that a high-affinity nitrate transport system from the unicellular green algae, Chlamydomonas reinhardtii required two gene products for function. One gene encoded a typical carrier-type structure with 12 putative trans-membrane (TM) domains and the other gene, nar2 encoded a much smaller protein that had only one TM domain. As both gene families occur in plants we investigated whether this transport model has more general relevance among plants. The screening for nitrate transporter activity was greatly helped by a novel assay using (15)N-enriched nitrate uptake into Xenopus oocytes expressing the proteins. This assay enables many oocytes to be rapidly screened for nitrate transport activity. The functional activity of a barley nitrate transporter, HvNRT2.1, in oocytes required co-injection of a second mRNA. Although three very closely related nar2-like genes were cloned from barley, only one of these was able to give functional nitrate transport when co-injected into oocytes. The nitrate transport performed by this two-gene system was inhibited at more acidic external pH and by acidification of the cytoplasm. This specific requirement for two-gene products to give nitrate transport function has important implications for attempts to genetically manipulate this fundamental process in plants. PMID:15659102

  8. The role of the cell cycle in the cellular uptake of folate-modified poly(l-amino acid) micelles in a cell population

    NASA Astrophysics Data System (ADS)

    Tang, Jihui; Liu, Ziwei; Ji, Fenqi; Li, Yao; Liu, Junjie; Song, Jian; Li, Jun; Zhou, Jianping

    2015-12-01

    Nanoparticles are widely recognized as a vehicle for tumor-targeted therapies. There are many factors that can influence the uptake of nanoparticles, such as the size of the nanoparticles, and/or their shape, elasticity, surface charge and even the cell cycle phase. However, the influence of the cell cycle on the active targeting of a drug delivery system has been unknown until now. In this study, we initially investigated the folate receptor α (FR-α) expression in different phases of HeLa cells by flow cytometric and immunocytochemical methods. The results obtained showed that FR-α expression was cell cycle-dependent, i.e. the S cells' folate receptor expression was the highest as the cell progressed through its cycle. Then, we used folate modified poly(l-amino acid) micelles (FA-PM) as an example to investigate the influence of the cell cycle on the active targeting drug delivery system. The results obtained indicated that the uptake of FA-PM by cells was influenced by the cell cycle phase, and the S cells took up the greatest number of folate conjugated nanoparticles. Our findings suggest that future studies on ligand-mediated active targeting preparations should consider the cell cycle, especially when this system is used for a cell cycle-specific drug.

  9. Excess cation uptake, and extrusion of protons and organic acid anions by Lupinus albus under phosphorus deficiency.

    PubMed

    Sas, L; Rengel, Z; Tang, C

    2001-05-01

    In symbiotically-grown legumes, rhizosphere acidification may be caused by a high cation/anion uptake ratio and the excretion of organic acids, the relative importance of the two processes depending on the phosphorus nutritional status of the plants. The present study examined the effect of P deficiency on extrusions of H(+) and organic acid anions (OA(-)) in relation to uptake of excess cations in N(2)-fixing white lupin (cv. Kiev Mutant). Plants were grown for 49 days in nutrient solutions treated with 1, 5 or 25 mmol P m(-3) Na(2)HPO(4) in a phytotron room. The increased formation of cluster roots occurred prior to a decrease in plant growth in response to P deficiency. The number of cluster roots was negatively correlated with tissue P concentrations below 2.0 g kg(-1) in shoots and 3 g kg(-1) in roots. Cluster roots generally had higher concentrations of Mg, Ca, N, Cu, Fe, and Mn but lower concentrations of K than non-cluster roots. Extrusion of protons and OA(-) (90% citrate and 10% malate) from roots was highly dependent on P supply. The amounts of H(+) extruded per unit root biomass decreased with time during the experiment. On the equimolar basis, H(+) extrusion by P-deficient plants (grown at 1 and 5 mmol P m(-3)) were, on average, 2-3-fold greater than OA(-) exudation. The excess cation content in plants was generally the highest at 1 mmol P m(-3) and decreased with increasing P supply. The ratio of H(+) release to excess cation uptake increased with decreasing P supply. The results suggest that increased exudation of OA(-) due to P deficiency is associated with H(+) extrusion but contributes only a part of total acidification. PMID:11337076

  10. Docosahexaenoyl ethanolamide improves glucose uptake and alters endocannabinoid system gene expression in proliferating and differentiating C2C12 myoblasts

    PubMed Central

    Kim, Jeffrey; Carlson, Morgan E.; Watkins, Bruce A.

    2014-01-01

    Skeletal muscle is a major storage site for glycogen and a focus for understanding insulin resistance and type-2-diabetes. New evidence indicates that overactivation of the peripheral endocannabinoid system (ECS) in skeletal muscle diminishes insulin sensitivity. Specific n-6 and n-3 polyunsaturated fatty acids (PUFA) are precursors for the biosynthesis of ligands that bind to and activate the cannabinoid receptors. The function of the ECS and action of PUFA in skeletal muscle glucose uptake was investigated in proliferating and differentiated C2C12 myoblasts treated with either 25 μM of arachidonate (AA) or docosahexaenoate (DHA), 25 μM of EC [anandamide (AEA), 2-arachidonoylglycerol (2-AG), docosahexaenoylethanolamide (DHEA)], 1 μM of CB1 antagonist NESS0327, and CB2 inverse agonist AM630. Compared to the BSA vehicle control cell cultures in both proliferating and differentiated myoblasts those treated with DHEA, the EC derived from the n-3 PUFA DHA, had higher 24 h glucose uptake, while AEA and 2-AG, the EC derived from the n-6 PUFA AA, had lower basal glucose uptake. Adenylyl cyclase mRNA was higher in myoblasts treated with DHA in both proliferating and differentiated states while those treated with AEA or 2-AG were lower compared to the control cell cultures. Western blot and qPCR analysis showed higher expression of the cannabinoid receptors in differentiated myoblasts treated with DHA while the opposite was observed with AA. These findings indicate a compensatory effect of DHA and DHEA compared to AA-derived ligands on the ECS and associated ECS gene expression and higher glucose uptake in myoblasts. PMID:24711795

  11. Impact of acid effluent from Kawah Ijen crater lake on irrigated agricultural soils: Soil chemical processes and plant uptake

    NASA Astrophysics Data System (ADS)

    van Rotterdam-Los, A. M. D.; Heikens, A.; Vriend, S. P.; van Bergen, M. J.; van Gaans, P. F. M.

    2008-12-01

    Volcanogenic contamination of irrigation water, caused by effluent from the hyperacid Ijen crater lake, has severely affected the properties of agricultural soils in East Java, Indonesia. From a comparison of acidified topsoil with subsoil and with top- and subsoil in a reference area, we identified processes responsible for changes in soil and soil solution chemistry induced by acid irrigation water, with emphasis on the nutrients Ca, Mg, Fe, and Mn, and on Al, which may become phytotoxic under acid conditions in soils. Compositional data for bulk soil composition and selective extractions with 1 M KCl and 0.2 M acid ammonium oxalate are used in a mass balance approach to specify element fluxes, including uptake by rice plants. The results show that input via irrigation water has produced an increase in the total aluminum content in the affected topsoil, which is of the same order of magnitude as the increase in labile Al. High bioavailability of Al, as reflected by concentrations in KCl extracts, is consistent with elevated concentrations observed in rice plants. In contrast, and despite the high input via irrigation water, Ca and Mg concentrations have decreased in all measured soil fractions through dissolution of amorphous phases and minerals, and through competition of Al for adsorption sites on the exchange complex and plant roots. Strong leaching is also evident for Fe and especially Mn. In terms of the overall mass balance of the topsoil, plant uptake of Al, Ca, Fe, Mg and Mn is negligible. If the use of acid irrigation would be stopped and the soil pH were to increase to values above 4.5, the observed phytotoxicity of Al will be halted. However, crops may then become fully dependent on the input from irrigation water or fertilizer for essential elements, due to the previous removal from the topsoil through leaching.

  12. Exogenous abscisic acid alleviates zinc uptake and accumulation in Populus × canescens exposed to excess zinc.

    PubMed

    Shi, Wen-Guang; Li, Hong; Liu, Tong-Xian; Polle, Andrea; Peng, Chang-Hui; Luo, Zhi-Bin

    2015-01-01

    A greenhouse experiment was conducted to study whether exogenous abscisic acid (ABA) mediates the responses of poplars to excess zinc (Zn). Populus × canescens seedlings were treated with either basal or excess Zn levels and either 0 or 10 μm ABA. Excess Zn led to reduced photosynthetic rates, increased Zn accumulation, induced foliar ABA and salicylic acid (SA), decreased foliar gibberellin (GA3 ) and auxin (IAA), elevated root H2 O2 levels, and increased root ratios of glutathione (GSH) to GSSG and foliar ratios of ascorbate (ASC) to dehydroascorbate (DHA) in poplars. While exogenous ABA decreased foliar Zn concentrations with 7 d treatments, it increased levels of endogenous ABA, GA3 and SA in roots, and resulted in highly increased foliar ASC accumulation and ratios of ASC to DHA. The transcript levels of several genes involved in Zn uptake and detoxification, such as yellow stripe-like family protein 2 (YSL2) and plant cadmium resistance protein 2 (PCR2), were enhanced in poplar roots by excess Zn but repressed by exogenous ABA application. These results suggest that exogenous ABA can decrease Zn concentrations in P. × canescens under excess Zn for 7 d, likely by modulating the transcript levels of key genes involved in Zn uptake and detoxification. PMID:25158610

  13. Uptake of dissolved free amino acids by four cold-water coral species from the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Gori, Andrea; Grover, Renaud; Orejas, Covadonga; Sikorski, Séverine; Ferrier-Pagès, Christine

    2014-01-01

    Dissolved organic matter, which contains many compounds such as lipids, sugars and amino acids, is an important source of carbon and nitrogen for several symbiotic and asymbiotic tropical coral species. However, there is still no information on its possible uptake by cold-water coral species. In this study, we demonstrated that dissolved organic matter, in the form of dissolved free amino acids (DFAA), is actively absorbed by four cold-water coral species from the Mediterranean Sea. Although the uptake rates observed with 3 μM DFAA concentration were one order of magnitude lower than those observed in tropical species, they corresponded to 12-50% of the daily excreted-nitrogen, and 16-89% of the daily respired-carbon of the cold-water corals. Consequently, DFAA, even at in situ concentrations lower than those tested in this study, can supply a significant amount of carbon and nitrogen to the corals, especially during periods when particulate food is scarce.

  14. Uptake and Intracellular Transport of Acidic Fibroblast Growth Factor: Evidence for Free and Cytoskeleton-anchored Fibroblast Growth Factor Receptors

    PubMed Central

    Citores, Lucía; Wesche, Jørgen; Kolpakova, Elona; Olsnes, Sjur

    1999-01-01

    Endocytic uptake and intracellular transport of acidic FGF was studied in cells transfected with FGF receptor 4 (FGFR4). Acidification of the cytosol to block endocytic uptake from coated pits did not inhibit endocytosis of the growth factor in COS cells transfected with FGFR4, indicating that it is to a large extent taken up by an alternative endocytic pathway. Fractionation of the cells demonstrated that part of the growth factor receptor was present in a low-density, caveolin-containing fraction, but we were unable to demonstrate binding to caveolin in immunoprecipitation studies. Upon treatment of the cells with acidic FGF, the activated receptor, together with the growth factor, moved to a juxtanuclear compartment, which was identified as the recycling endosome compartment. When the cells were lysed with Triton X-100, 3-([3-chloramidopropyl]dimethylammonio)-2-hydroxy-1-propanesulfonate, or 2-octyl glucoside, almost all surface-exposed and endocytosed FGFR4 was solubilized, but only a minor fraction of the total FGFR4 in the cells was found in the soluble fraction. The data indicate that the major part of FGFR4 is anchored to detergent-insoluble structures, presumably cytoskeletal elements associated with the recycling endosome compartment. PMID:10564275

  15. Effect of basic amino acids and aminoglycosides on /sup 3/H-gentamicin uptake in cortical slices of rat and human kindney

    SciTech Connect

    Bennett, W.M.; Plamp, C.E.; Elliott, W.C.; Parker, R.A.; Porter, G.A.

    1982-02-01

    The uptake of /sup 3/H-gentamicin was assessed in renal cortical slices of Fischer 344 male rats and four human cadaver kidneys not utilized for renal transplantation. In both species the uptake was maximal at 90 min and maintained a steady state therafter. The characteristics of the energy-dependent component of /sup 3/H-gentamicin uptake were not altered by various basic amino acids, but competitive inhibition was induced by other aminoglycosides in a dose-dependent fashion. Thus aminoglycosides appear to share a transport process that is distinct from those of organic bases or other cationic substances. In addition, under the experimental conditions employed, the basolateral membranes of the tubular cell is capable of energy-dependent uptake of gentamicin. The role of this route of cellular uptake of aminoglycoside in clinical nephrotoxicity is speculative.

  16. Topical imiquimod yields systemic effects due to unintended oral uptake.

    PubMed

    Grine, Lynda; Steeland, Sophie; Van Ryckeghem, Sara; Ballegeer, Marlies; Lienenklaus, Stefan; Weiss, Siegfried; Sanders, Niek N; Vandenbroucke, Roosmarijn E; Libert, Claude

    2016-01-01

    Repetitive application of topical imiquimod is used as an experimental model for the induction of psoriasiform skin lesions in mice. The model is characterized by several inflammatory processes, including cytokine production both locally and systemically, cellular infiltration, and splenomegaly. To investigate the production of type I interferons in response to imiquimod-containing Aldara cream, IFNβ-luciferase reporter mice were imaged in vivo and ex vivo. Type I interferons were found to be produced in the skin, but also in the intestinal system caused by unintended ingestion of imiquimod by the mice. Through the use of Elizabethan collars to prevent ingestion, these effects, including psoriasiform lesions were nearly completely prevented. Our findings reveal that topical treatment with Aldara induces a psoriasiform skin inflammation, but that its mode of action depends on ingestion of the chemical, which leads to systemic responses and affects local inflammation. Therefore, potential ingestion of topical treatments during experimental procedures should be taken into account during assessment of cutaneous inflammatory parameters in skin disease models. PMID:26818707

  17. Topical imiquimod yields systemic effects due to unintended oral uptake

    PubMed Central

    Grine, Lynda; Steeland, Sophie; Van Ryckeghem, Sara; Ballegeer, Marlies; Lienenklaus, Stefan; Weiss, Siegfried; Sanders, Niek N.; Vandenbroucke, Roosmarijn E.; Libert, Claude

    2016-01-01

    Repetitive application of topical imiquimod is used as an experimental model for the induction of psoriasiform skin lesions in mice. The model is characterized by several inflammatory processes, including cytokine production both locally and systemically, cellular infiltration, and splenomegaly. To investigate the production of type I interferons in response to imiquimod-containing Aldara cream, IFNβ-luciferase reporter mice were imaged in vivo and ex vivo. Type I interferons were found to be produced in the skin, but also in the intestinal system caused by unintended ingestion of imiquimod by the mice. Through the use of Elizabethan collars to prevent ingestion, these effects, including psoriasiform lesions were nearly completely prevented. Our findings reveal that topical treatment with Aldara induces a psoriasiform skin inflammation, but that its mode of action depends on ingestion of the chemical, which leads to systemic responses and affects local inflammation. Therefore, potential ingestion of topical treatments during experimental procedures should be taken into account during assessment of cutaneous inflammatory parameters in skin disease models. PMID:26818707

  18. Bioavailability of Fullerene under Environmentally Relevant Conditions: Effects of Humic Acid and Fetal Bovine Serum on Accumulation in Lipid Bilayers and Cellular Uptake.

    PubMed

    Ha, Yeonjeong; Wang, Xianzhe; Liljestrand, Howard M; Maynard, Jennifer A; Katz, Lynn E

    2016-07-01

    Carbon fullerene (C60) has emerged at the forefront of nanoscale research and application due to its unique properties. As the production of this nanoparticle rapidly increases, it can be released into natural aquatic environments and can accumulate in biological systems. This research examined the effects of humic acid and fetal bovine serum (FBS), which are ubiquitous in aquatic environments and representative of blood plasma in living organisms, respectively, on bioavailability of fullerene. Bioavailability was investigated using in vitro methods for lipid membrane accumulation and cellular uptake studies. Humic acid and FBS significantly changed the characteristics of fullerene including its particle size and surface charge. The effects of humic acid on lipid accumulation of fullerene depended on the lipid head charge. FBS also significantly decreased the lipid accumulation when positively charged and zwitterionic head groups were present on the lipids, possibly due to the higher steric repulsion of the protein coated nanoparticles. In addition, both humic acid and FBS protein effectively lowered the amounts of fullerene taken up by Caco-2 cells, which are derived from a human colorectal adenocarcinoma and have similar functions to the small intestinal epithelium. Results of this study suggest that surface modification of fullerene by environmentally relevant matrices can significantly affect the biological transport, as well as the possible toxicity of this nanomaterial. PMID:26943027

  19. Anti-1-Amino-3-18F-Fluorocyclobutane-1-Carboxylic Acid: Physiologic Uptake Patterns, Incidental Findings, and Variants That May Simulate Disease

    PubMed Central

    Schuster, David M.; Nanni, Cristina; Fanti, Stefano; Oka, Shuntaro; Okudaira, Hiroyuki; Inoue, Yusuke; Sörensen, Jens; Owenius, Rikard; Choyke, Peter; Turkbey, Baris; Bogsrud, Trond V.; Bach-Gansmo, Tore; Halkar, Raghuveer K.; Nye, Jonathon A.; Odewole, Oluwaseun A.; Savir-Baruch, Bital; Goodman, Mark M.

    2016-01-01

    Anti-1-amino-3-18F-fluorocyclobutane-1-carboxylic acid (18F-FACBC) is a synthetic amino acid analog PET radiotracer undergoing clinical trials for the evaluation of prostate and other cancers. We aimed to describe common physiologic uptake patterns, incidental findings, and variants in patients who had undergone 18F-FACBC PET. Methods Sixteen clinical trials involving 611 18F-FACBC studies from 6 centers, which included dosimetry studies on 12 healthy volunteers, were reviewed. Qualitative observations of common physiologic patterns, incidental uptake, and variants that could simulate disease were recorded and compared with similar observations in studies of the healthy volunteers. Quantitative analysis of select data and review of prior published reports and observations were also made. Results The liver and pancreas demonstrated the most intense uptake. Moderate salivary and pituitary uptake and variable mild to moderate bowel activity were commonly visualized. Moderate bone marrow and mild muscle activity were present on early images, with marrow activity decreasing and muscle activity increasing with time. Brain and lungs demonstrated activity less than blood pool. Though 18F-FACBC exhibited little renal excretion or bladder uptake during the clinically useful early imaging time window, mild to moderate activity might accumulate in the bladder and interfere with evaluation of adjacent prostate bed and seminal vesicles in 5%–10% of patients. Uptake might also occur from benign processes such as infection, inflammation, prostatic hyperplasia, and metabolically active benign bone lesions such as osteoid osteoma. Conclusion Common physiologic uptake patterns were similar to those noted in healthy volunteers. The activity in organs followed the presence of amino acid transport and metabolism described with other amino acid–based PET radiotracers. As with other PET radiotracers such as 18F-FDG, focal nonphysiologic uptake may represent incidental malignancy

  20. Enhanced cellular uptake of protoporphyrine IX/linolenic acid-conjugated spherical nanohybrids for photodynamic therapy.

    PubMed

    Lee, Hye-In; Kim, Young-Jin

    2016-06-01

    Protoporphyrin IX (PpIX) has wide applications in photodynamic diagnosis and photodynamic therapy (PDT) in many human diseases. However, poor water solubility and cancer cell localization limit its direct application for PDT. We improved the water-solubility and cellular internalization of PpIX to enhance PDT efficacy by developing biocompatible PpIX/linolenic acid-conjugated polyhedral oligomeric silsesquioxane (PPLA) nanohybrids. The resulting PPLA nanohybrids exhibited a quasi-spherical shape with a size of <200nm. (1)H NMR analysis confirmed the synthesis of PPLA. The singlet oxygen formation of PPLA nanohybrids on laser irradiation was detected by photoluminescence emission. Fluorescence-activated cell sorting (FACS) analysis displayed higher cellular internalization of PPLA compared with free PpIX. In addition, PPLA nanohybrids exhibited significantly reduced dark-toxicity and a high phototoxicity mostly because of apoptotic cell death against human gastric cancer cells. These results imply that the PPLA nanohybrid system may be applicable in PDT. PMID:26954084

  1. EFFECT OF ACIDIC CONDITIONS ON CADMIUM UPTAKE BY THREE AQUATIC PLANTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acidic runoff from mining and storage of mined materials creates an undesirable environmental impact on both flora and fauna. Presence of heavy metals such as Cadmium (CD) creates an additional negative factor in acidic environments. Accumulation of Cd in plant tissues of aquatic vascular plants i...

  2. Identification and Functions of Amino Acid Residues in PotB and PotC Involved in Spermidine Uptake Activity*

    PubMed Central

    Higashi, Kyohei; Sakamaki, Yoshiharu; Herai, Emiko; Demizu, Risa; Uemura, Takeshi; Saroj, Sunil D.; Zenda, Risa; Terui, Yusuke; Nishimura, Kazuhiro; Toida, Toshihiko; Kashiwagi, Keiko; Igarashi, Kazuei

    2010-01-01

    Amino acid residues on PotB and PotC involved in spermidine uptake were identified by random and site-directed mutagenesis. It was found that Trp8, Tyr43, Trp100, Leu110, and Tyr261 in PotB and Trp46, Asp108, Glu169, Ser196, Asp198, and Asp199 in PotC were strongly involved in spermidine uptake and that Tyr160, Glu172, and Leu274 in PotB and Tyr19, Tyr88, Tyr148, Glu160, Leu195, and Tyr211 in PotC were moderately involved in spermidine uptake. Among 11 amino acid residues that were strongly involved in spermidine uptake, Trp8 in PotB was important for insertion of PotB and PotC into membranes. Tyr43, Trp100, and Leu110 in PotB and Trp46, Asp108, Ser196, and Asp198 in PotC were found to be involved in the interaction with PotD. Leu110 and Tyr261 in PotB and Asp108, Asp198, and Asp199 in PotC were involved in the recognition of spermidine, and Trp100 and Tyr261 in PotB and Asp108, Glu169, and Asp198 in PotC were involved in ATPase activity of PotA. Accordingly, Trp100 in PotB was involved in both PotD recognition and ATPase activity, Leu110 in PotB was involved in both PotD and spermidine recognition, and Tyr261 in PotB was involved in both spermidine recognition and ATPase activity. Asp108 and Asp198 in PotC were involved in PotD and spermidine recognition as well as ATPase activity. These results suggest that spermidine passage from PotD to the cytoplasm is coupled to the ATPase activity of PotA through a structural change of PotA by its ATPase activity. PMID:20937813

  3. Genetically designed biomolecular capping system for mesoporous silica nanoparticles enables receptor-mediated cell uptake and controlled drug release

    NASA Astrophysics Data System (ADS)

    Datz, Stefan; Argyo, Christian; Gattner, Michael; Weiss, Veronika; Brunner, Korbinian; Bretzler, Johanna; von Schirnding, Constantin; Torrano, Adriano A.; Spada, Fabio; Vrabel, Milan; Engelke, Hanna; Bräuchle, Christoph; Carell, Thomas; Bein, Thomas

    2016-04-01

    Effective and controlled drug delivery systems with on-demand release and targeting abilities have received enormous attention for biomedical applications. Here, we describe a novel enzyme-based cap system for mesoporous silica nanoparticles (MSNs) that is directly combined with a targeting ligand via bio-orthogonal click chemistry. The capping system is based on the pH-responsive binding of an aryl-sulfonamide-functionalized MSN and the enzyme carbonic anhydrase (CA). An unnatural amino acid (UAA) containing a norbornene moiety was genetically incorporated into CA. This UAA allowed for the site-specific bio-orthogonal attachment of even very sensitive targeting ligands such as folic acid and anandamide. This leads to specific receptor-mediated cell and stem cell uptake. We demonstrate the successful delivery and release of the chemotherapeutic agent Actinomycin D to KB cells. This novel nanocarrier concept provides a promising platform for the development of precisely controllable and highly modular theranostic systems.Effective and controlled drug delivery systems with on-demand release and targeting abilities have received enormous attention for biomedical applications. Here, we describe a novel enzyme-based cap system for mesoporous silica nanoparticles (MSNs) that is directly combined with a targeting ligand via bio-orthogonal click chemistry. The capping system is based on the pH-responsive binding of an aryl-sulfonamide-functionalized MSN and the enzyme carbonic anhydrase (CA). An unnatural amino acid (UAA) containing a norbornene moiety was genetically incorporated into CA. This UAA allowed for the site-specific bio-orthogonal attachment of even very sensitive targeting ligands such as folic acid and anandamide. This leads to specific receptor-mediated cell and stem cell uptake. We demonstrate the successful delivery and release of the chemotherapeutic agent Actinomycin D to KB cells. This novel nanocarrier concept provides a promising platform for the

  4. Antioxidant modulation of oxidant-stimulated uptake and release of arachidonic acid in eicosapentaenoic acid-supplemented human lymphoma U937 cells.

    PubMed

    Obajimi, Oluwakemi; Black, Kenneth D; Glen, Iain; Ross, Brian M

    2007-02-01

    Omega-3 polyunsaturated fatty acids (PUFA) are increasingly finding use as treatments for a variety of medical conditions. PUFA supplementation can, however, result in increased oxidative stress causing elevated turnover rate of membrane phospholipids, impairment of membrane integrity and increased formation of inflammatory mediators. The aim of this study was to determine which antioxidant compounds were most effective in ameliorating the stimulation of phospholipid turnover by oxidative stress. U937 cells were supplemented with eicosapentaenoic acid and either ascorbic acid, alpha-tocopherol, beta-carotene or astaxanthin prior to being challenged with oxidant. Although all antioxidants were found to be effective in decreasing oxidant-stimulated peroxide formation, only alpha-tocopherol significantly decreased oxidant-stimulated release of 3H-labeled arachidonic acid (AA), while ascorbic acid markedly increased release. All antioxidants except alpha-tocopherol decreased oxidant-stimulated 3H-AA uptake. Our data suggest that antioxidants are not equally effective in combating the effects of oxidative stress upon membrane phospholipid turnover, and that optimal protection will require mixtures of antioxidants. PMID:17198751

  5. Selective retrograde labeling of lateral olivocochlear neurons in the brainstem based on preferential uptake of 3H-D-aspartic acid in the cochlea

    SciTech Connect

    Ryan, A.F.; Schwartz, I.R.; Helfert, R.H.; Keithley, E.; Wang, Z.X.

    1987-01-22

    We have previously shown that perfusion of the gerbil cochlea with probe concentrations of /sup 3/H-D-aspartic acid (D-ASP) results in immediate, selective labeling of 50-60% of the efferent terminals under the inner hair cells, presumably by high-affinity uptake. The present study was undertaken to determine the origin of these endings. Twenty-four hours after cochlear perfusion with D-ASP, labeled neurons were observed in the ipsilateral, and to a much lesser extent in the contralateral, lateral superior olivary nucleus (LSO). The cells were small, primarily fusiform, and showed fewer synaptic contacts than other LSO cells. Combined transport of D-ASP and horseradish peroxidase indicated that all olivocochlear neurons within the LSO that projected to the injected cochlea were labeled by D-ASP. Labeled fibers coursed dorsally from the LSO, joined contralateral fibers that had passed under the floor of the fourth ventricle, and entered the VIIIth nerve root at its ventromedial edge. Adjacent to the ventral cochlear nucleus (VCN), densely labeled collateral fibers crossed the nerve root to enter the VCN. Labeled fibers and terminals were prominent in the central VCN. Neither retrograde transport of D-ASP by medial olivocochlear and vestibular efferents nor anterograde transport by VIIIth nerve afferents was observed. The D-ASP-labeled cells and fibers are clearly lateral olivocochlear efferents. Retrograde transport of D-ASP thus allows the cells, axons, and collaterals of the lateral olivocochlear system to be studied, morphologically, in isolation from other cells that project to the cochlea. Since the olivocochlear neurons are almost certainly cholinergic, retrograde amino acid transport does not necessarily identify the primary neurotransmitter of a neuron. Rather, it indicates the presence of selective uptake by the processes of that neuron at the site of amino acid injection.

  6. Stimulatory effect of isoferulic acid on alpha1A-adrenoceptor to increase glucose uptake into cultured myoblast C2C12 cell of mice.

    PubMed

    Liu, I M; Tsai, C C; Lai, T Y; Cheng, J T

    2001-05-14

    In an attempt to elucidate the effect of isoferulic acid on alpha1-adrenoceptor (AR), the myoblast C2C12 cells of mice were employed to investigate the change of glucose uptake in the present study. Isoferulic acid enhanced the uptake of radioactive glucose into C2C12 cells in a concentration-dependent manner, which were abolished by pretreatment with prazosin. Effect of isoferulic acid on alpha1-AR was further characterized using the displacement of [3H]YM617 binding in C2C12 cells. The radioactive glucose uptake increasing action of isoferulic acid was abolished by tamsulosin or WB 4101 at concentration sufficient to block alpha1A-adrenoceptor (alpha1A-AR) but it was not modified by chlorethylclonidine (CEC) at the concentration sufficient to abolish alpha1B-AR. An activation of alpha1A-AR by isoferulic acid in C2C12 cells can thus be considered. Pharmacological inhibition of phospholipase C (PLC) by U73312 resulted in a concentration-dependent reduction of isoferulic acid-stimulated glucose uptake in C2C12 cells. This inhibition by U73112 was specific because the inactive congener, U73343, failed to modify the action of isoferulic acid. Also, chelerythrine and GF 109203X diminished the action of isoferulic acid at concentration sufficient to inhibit the activity of protein kinase C (PKC). The obtained data suggest that an activation of alpha1A-AR by isoferulic acid may increase the glucose uptake via PLC-PKC pathway in C2C12 cells. PMID:11474559

  7. Amino acid transport across the tonoplast of vacuoles isolated from barley mesophyll protoplasts: Uptake of alanine, leucine, and glutamine. [Hordeum vulgare L

    SciTech Connect

    Dietz, K.J.; Jaeger, R.; Kaiser, G.; Martinoia, E. )

    1990-01-01

    Mesophyll protoplasts from leaves of well-fertilized barley (Hordeum vulgare L.) plants contained amino acids at concentrations as high as 120 millimoles per liter. With the exception of glutamic acid, which is predominantly localized in the cytoplasm, a major part of all other amino acids was contained inside the large central vacuole. Alanine, leucine, and glutamine are the dominant vacuolar amino acids in barley. Their transport into isolated vacuoles was studied using {sup 14}C-labeled amino acids. Uptake was slow in the absence of ATP. A three- to sixfold stimulation of uptake was observed after addition of ATP or adenylyl imidodiphosphate an ATP analogue not being hydrolyzed by ATPases. Other nucleotides were ineffective in increasing the rate of uptake. ATP-Stimulated amino acid transport was not dependent on the transtonoplast pH or membrane potential. p-Chloromercuriphenylsulfonic acid and n-ethyl maleimide increased transport independently of ATP. Neutral amino acids such as valine or leucine effectively decreased the rate of alanine transport. Glutamine and glycine were less effective or not effective as competitive inhibitors of alanine transport. The results indicate the existence of a uniport translocator specific for neutral or basic amino acids that is under control of metabolic effectors.

  8. Synthesis of 4-substituted nipecotic acid derivatives and their evaluation as potential GABA uptake inhibitors.

    PubMed

    Hellenbrand, Tim; Höfner, Georg; Wein, Thomas; Wanner, Klaus T

    2016-05-01

    In this study, we disclose the design and synthesis of novel 4-susbtituted nipecotic acid derivatives as inhibitors of the GABA transporter mGAT1. Based on molecular modeling studies the compounds are assumed to adopt a binding pose similar to that of the potent mGAT1 inhibitor nipecotic acid. As substitution in 4-position should not cause an energetically unfavorable orientation of nipecotic acid as it is the case for N-substituted derivatives this is expected to lead to highly potent binders. For the synthesis of novel 4-substituted nipecotic acid derivatives a linear synthetic strategy was employed. As a key step, palladium catalyzed cross coupling reactions were used to attach the required biaryl moieties to the ω-position of the alkenyl- or alkynyl spacers of varying length in the 4-position of the nipecotic acid scaffold. The resulting amino acids were characterized with respect to their binding affinities and inhibitory potencies at mGAT1. Though the biological activities found were generally insignificant to poor, two compounds, one of which possesses a reasonable binding affinity for mGAT1, rac-57, the other a notable inhibitory potency at mGAT4, rac-84, both displaying a slight subtype selectivity for the individual transporters, could be identified. PMID:27039250

  9. Variation for N Uptake System in Maize: Genotypic Response to N Supply.

    PubMed

    Garnett, Trevor; Plett, Darren; Conn, Vanessa; Conn, Simon; Rabie, Huwaida; Rafalski, J Antoni; Dhugga, Kanwarpal; Tester, Mark A; Kaiser, Brent N

    2015-01-01

    An understanding of the adaptations made by plants in their nitrogen (N) uptake systems in response to reduced N supply is important to the development of cereals with enhanced N uptake efficiency (NUpE). Twenty seven diverse genotypes of maize (Zea mays, L.) were grown in hydroponics for 3 weeks with limiting or adequate N supply. Genotypic response to N was assessed on the basis of biomass characteristics and the activities of the nitrate ([Formula: see text]) and ammonium ([Formula: see text]) high-affinity transport systems. Genotypes differed greatly for the ability to maintain biomass with reduced N. Although, the N response in underlying biomass and N transport related characteristics was less than that for biomass, there were clear relationships, most importantly, lines that maintained biomass at reduced N maintained net N uptake with no change in size of the root relative to the shoot. The root uptake capacity for both [Formula: see text] and [Formula: see text] increased with reduced N. Transcript levels of putative [Formula: see text] and [Formula: see text] transporter genes in the root tissue of a subset of the genotypes revealed that predominately ZmNRT2 transcript levels responded to N treatments. The correlation between the ratio of transcripts of ZmNRT2.2 between the two N levels and a genotype's ability to maintain biomass with reduced N suggests a role for these transporters in enhancing NUpE. The observed variation in the ability to capture N at low N provides scope for both improving NUpE in maize and also to better understand the N uptake system in cereals. PMID:26617612

  10. Variation for N Uptake System in Maize: Genotypic Response to N Supply

    PubMed Central

    Garnett, Trevor; Plett, Darren; Conn, Vanessa; Conn, Simon; Rabie, Huwaida; Rafalski, J. Antoni; Dhugga, Kanwarpal; Tester, Mark A.; Kaiser, Brent N.

    2015-01-01

    An understanding of the adaptations made by plants in their nitrogen (N) uptake systems in response to reduced N supply is important to the development of cereals with enhanced N uptake efficiency (NUpE). Twenty seven diverse genotypes of maize (Zea mays, L.) were grown in hydroponics for 3 weeks with limiting or adequate N supply. Genotypic response to N was assessed on the basis of biomass characteristics and the activities of the nitrate (NO3−) and ammonium (NH4+) high-affinity transport systems. Genotypes differed greatly for the ability to maintain biomass with reduced N. Although, the N response in underlying biomass and N transport related characteristics was less than that for biomass, there were clear relationships, most importantly, lines that maintained biomass at reduced N maintained net N uptake with no change in size of the root relative to the shoot. The root uptake capacity for both NO3− and NH4+ increased with reduced N. Transcript levels of putative NO3− and NH4+ transporter genes in the root tissue of a subset of the genotypes revealed that predominately ZmNRT2 transcript levels responded to N treatments. The correlation between the ratio of transcripts of ZmNRT2.2 between the two N levels and a genotype's ability to maintain biomass with reduced N suggests a role for these transporters in enhancing NUpE. The observed variation in the ability to capture N at low N provides scope for both improving NUpE in maize and also to better understand the N uptake system in cereals. PMID:26617612

  11. Characterization of a Dipartite Iron Uptake System from Uropathogenic Escherichia coli Strain F11*

    PubMed Central

    Koch, Doreen; Chan, Anson C. K.; Murphy, Michael E. P.; Lilie, Hauke; Grass, Gregor; Nies, Dietrich H.

    2011-01-01

    In the uropathogenic Escherichia coli strain F11, in silico genome analysis revealed the dicistronic iron uptake operon fetMP, which is under iron-regulated control mediated by the Fur regulator. The expression of fetMP in a mutant strain lacking known iron uptake systems improved growth under iron depletion and increased cellular iron accumulation. FetM is a member of the iron/lead transporter superfamily and is essential for iron uptake by the Fet system. FetP is a periplasmic protein that enhanced iron uptake by FetM. Recombinant FetP bound Cu(II) and the iron analog Mn(II) at distinct sites. The crystal structure of the FetP dimer reveals a copper site in each FetP subunit that adopts two conformations: CuA with a tetrahedral geometry composed of His44, Met90, His97, and His127, and CuB, a second degenerate octahedral geometry with the addition of Glu46. The copper ions of each site occupy distinct positions and are separated by ∼1.3 Å. Nearby, a putative additional Cu(I) binding site is proposed as an electron source that may function with CuA/CuB displacement to reduce Fe(III) for transport by FetM. Together, these data indicate that FetMP is an additional iron uptake system composed of a putative iron permease and an iron-scavenging and potentially iron-reducing periplasmic protein. PMID:21596746

  12. PGC-1α Coordinates Mitochondrial Respiratory Capacity and Muscular Fatty Acid Uptake via Regulation of VEGF-B.

    PubMed

    Mehlem, Annika; Palombo, Isolde; Wang, Xun; Hagberg, Carolina E; Eriksson, Ulf; Falkevall, Annelie

    2016-04-01

    Vascular endothelial growth factor (VEGF) B belongs to the VEGF family, but in contrast to VEGF-A, VEGF-B does not regulate blood vessel growth. Instead, VEGF-B controls endothelial fatty acid (FA) uptake and was identified as a target for the treatment of type 2 diabetes. The regulatory mechanisms controlling Vegfb expression have remained unidentified. We show that peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) together with estrogen-related receptor α (ERR-α) regulates expression of Vegfb Mice overexpressing PGC-1α under the muscle creatine kinase promoter (MPGC-1αTG mice) displayed increased Vegfb expression, and this was accompanied by increased muscular lipid accumulation. Ablation of Vegfb in MPGC-1αTG mice fed a high-fat diet (HFD) normalized glucose intolerance, insulin resistance, and dyslipidemia. We suggest that VEGF-B is the missing link between PGC-1α overexpression and the development of the diabetes-like phenotype in HFD-fed MPGC-1αTG mice. The findings identify Vegfb as a novel gene regulated by the PGC-1α/ERR-α signaling pathway. Furthermore, the study highlights the role of PGC-1α as a master metabolic sensor that by regulating the expression levels of Vegfa and Vegfb coordinates blood vessel growth and FA uptake with mitochondrial FA oxidation. PMID:26822083

  13. Uptake of Nitrite by Neurospora crassa

    PubMed Central

    Schloemer, Robert H.; Garrett, Reginald H.

    1974-01-01

    Like the nitrate transport system, the nitrite uptake system in Neurospora crassa is induced by either nitrate or nitrite. This induction is prevented by cycloheximide, puromycin, or 6-methyl purine. The Km for nitrite of the induced nitrite uptake system is 86 μM, and the Vmax is 100 μmol of nitrite per g (wet weight) per h. Nitrite uptake is inhibited by metabolic poisons such as arsenate, dinitrophenol, cyanide, and antimycin A. No repression or inhibition of the nitrite transport system by ammonia, nitrate, or Casamino Acids was observed. PMID:4274458

  14. Water uptake by a maize root system - An explicit numerical 3-dimensional simulation.

    NASA Astrophysics Data System (ADS)

    Leitner, Daniel; Schnepf, Andrea; Klepsch, Sabine; Roose, Tiina

    2010-05-01

    Water is one of the most important resources for plant growth and function. An accurate modelling of the unsaturated flow is not only substantial to predict water uptake but also important to describe nutrient movement regarding water saturation and transport. In this work we present a model for water uptake. The model includes the simultaneous flow of water inside the soil and inside the root network. Water saturation in the soil volume is described by the Richards equation. Water flow inside the roots' xylem is calculated using the Poiseuille law for water flow in a cylindrical tube. The water saturation in the soil as well as water uptake of the root system is calculated numerically in three dimensions. We study water uptake of a maize plant in a confined pot under different supply scenarios. The main improvement of our approach is that the root surfaces act as spatial boundaries of the soil volume. Therefore water influx into the root is described by a surface flux instead of a volume flux, which is commonly given by an effective sink term. For the numerical computation we use the following software: The 3-dimensional maize root architecture is created by a root growth model based on L-Systems (Leitner et al 2009). A mesh of the surrounding soil volume is created using the meshing software DistMesh (Persson & Strang 2004). Using this mesh the partial differential equations are solved with the finite element method using Comsol Multiphysics 3.5a. Modelling results are related to accepted water uptake models from literature (Clausnitzer & Hopmans 1994, Roose & Fowler 2004, Javaux et al 2007). This new approach has several advantages. By considering the individual roots it is possible to analyse the influence of overlapping depletion zones due to inter root competition. Furthermore, such simulations can be used to estimate the influence of simplifying assumptions that are made in the development of effective models. The model can be easily combined with a nutrient

  15. MINIATURE ACID CONDENSATION SYSTEM: DESIGN AND OPERATION

    EPA Science Inventory

    An extractive source sampling system was designed and constructed. The sampling system measures gaseous sulfuric acid and sulfur dioxide in combustion emissions. The miniature acid condensation system (MACS) includes a high-temperature quartz probe and quartz-filter holder. Since...

  16. Behaviors of acrylamide/itaconic acid hydrogels in uptake of uranyl ions from aqueous solutions

    SciTech Connect

    Karadag, E.; Saraydin, D.; Gueven, O.

    1995-12-01

    In this study, adsorptions of uranyl ions from two different aqueous uranyl solutions by acrylamide-itaconic acid hydrogels were investigated by a spectroscopic method. The hydrogels were prepared by irradiating with {gamma}-radiation. In the experiment of uranyl ions adsorption, Type II adsorption was found. One gram of acrylamide-itaconic acid hydrogels sorbed 178-219 mg uranyl ions from the solutions of uranyl acetate, 42-76 mg uranyl ions from the aqueous solutions of uranyl nitrate, while acrylamide hydrogel did not sorb any uranyl ion. For the hydrogel containing 40 mg of itaconic acid and irradiated to 3.73 kGy, swelling of the hydrogels was observed in water (1660%), in the aqueous solution of uranyl acetate (730%), and in the aqueous solution of uranyl nitrate (580%). Diffusions of water onto hydrogels were a non-Fickian type of diffusion, whereas diffusions of uranyl ions were a Fickian type of diffusion.

  17. Methane uptake and emissions in a typical steppe grazing system during the grazing season

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoya; Zhang, Yingjun; Huang, Ding; Li, Zhiqiang; Zhang, Xiaoqing

    2015-03-01

    This study investigated the effects of livestock grazing on CH4 emissions by testing six grazing conditions at Guyuan State Key Monitoring and Research Station of Grassland Ecosystem (China) in 2011 and 2012. Under all grazing systems, steppe soils were measured to be CH4 sinks. The uptake of CH4 by grassland was primarily determined by topsoil (7 cm) temperature and soil (0-7 cm) moisture in grassland at short-term grazing and non-grazing. The cumulative uptake of CH4 during the grazing period for all conditions was 0.88-3.23 kg hm-2 CH4, and the highest level was observed in the continuously moderate grazing condition. Reducing grazing stocking in the short-term did not significantly change the uptake of CH4 when compared with continuously heavy grazing condition. Enteric CH4 emissions were not significantly affected by the grazing period or conditions. The uptake of CH4 by grassland soil offset 3.1-8.6% of the CH4 emissions from the grazing sheep and was most effective at the continuously moderate grazing condition. These findings imply that continuously moderate grazing is the best approach considered here for optimizing the soil as a sink for atmospheric CH4.

  18. Effects of acidic deposition on nutrient uptake, nutrient cycling and growth processes of vegetation in the spruce-fir ecosystem

    SciTech Connect

    McLaughlin, S.B.; Garten, C.T.; Wullschleger, S.D.

    1996-10-16

    This report summarizes progress in three years of field research designed to evaluate biological and chemical indicators of the current and future health of the Southern Appalachian spruce-fir ecosystem. The emphasis of this research has been on the identification and understanding of mechanisms through which current levels of acidic deposition are impacting ecosystem processes. The identification of these principal mechanisms and key biological indicators of change was designed to improve our capabilities to detect, monitor, and assess the effects of air quality regulations and attendant future air quality changes on ecosystem response. Individual research tasks focused on the following research areas: (1) the significance of foliar uptake of atmospheric sources of nitrogen in relationship to plant utilization of N from available soil reserves; (2) linkages between atmospheric inputs to the soil surface, solution chemistry, and decomposition in the upper organic soil horizons; (3) effects of soil solution chemistry on uptake of cations and aluminum by fine roots; and (4) the effects of varying rates of calcium supply on carbon metabolism of Fraser fir and red spruce, and the relationship between calcium levels in wood cells and integrity of wood formed in bole and branches. Each of the individual tasks was designed to focus upon a mechanism or process that we consider critical to understanding chemical and biological linkages. These linkages will be important determinants in understanding the basis of past and potential future responses of the high elevation Southern Appalachian Forest to acidic deposition and other co-occurring environmental stresses. This report contains (1) background and rationale for the research undertaken in 1992-94; (2) a summary of principal research findings; (3) publications from this research; and (4) characterization of data sets produced by this research which will be the basis of future research, analyses and/or publications.

  19. Root-zone acidity and nitrogen source affects Typha latifolia L. growth and uptake kinetics of ammonium and nitrate.

    PubMed

    Brix, Hans; Dyhr-Jensen, Kirsten; Lorenzen, Bent

    2002-12-01

    The NH(4)(+) and NO(3)(-) uptake kinetics by Typha latifolia L. were studied after prolonged hydroponics growth at constant pH 3.5, 5.0, 6.5 or 7.0 and with NH(4)(+) or NO(3)(-) as the sole N-source. In addition, the effects of pH and N source on H(+) extrusion and adenine nucleotide content were examined. Typha latifolia was able to grow with both N sources at near neutral pH levels, but the plants had higher relative growth rates, higher tissue concentrations of the major nutrients, higher contents of adenine nucleotides, and higher affinity for uptake of inorganic nitrogen when grown on NH(4)(+). Growth almost completely stopped at pH 3.5, irrespective of N source, probably as a consequence of pH effects on plasma membrane integrity and H(+) influx into the root cells. Tissue concentrations of the major nutrients and adenine nucleotides were severely reduced at low pH, and the uptake capacity for inorganic nitrogen was low, and more so for NO(3)(-)-fed than for NH(4)(+)-fed plants. The maximum uptake rate, V(max), was highest for NH(4)(+) at pH 6.5 (30.9 micro mol h(-1) g(-1) root dry weight) and for NO(3)(-) at pH 5.0 (31.7 micro mol h(-1) g(-1) root dry weight), and less than 10% of these values at pH 3.5. The affinity for uptake as estimated by the half saturation constant, K((1/2)), was lowest at low pH for NH(4)(+) and at high pH for NO(3)(-). The changes in V(max) and K((1/2)) were thus consistent with the theory of increasing competition between cations and H(+) at low pH and between anions and OH(-) at high pH. C(min) was independent of pH, but slightly higher for NO(3)(-) than for NH(4)(+) (C(min)(NH(4)(+)) approximately 0.8 mmol m(-3); C(min)(NO(3)(-)) approximately 2.8 mmol m(-3)). The growth inhibition at low pH was probably due to a reduced nutrient uptake and a consequential limitation of growth by nutrient stress. Typha latifolia seems to be well adapted to growth in wetland soils where NH(4)(+) is the prevailing nitrogen compound, but very low p

  20. Surfactant Control of HCl and HBr Uptake into Supercooled Sulfuric Acid

    NASA Astrophysics Data System (ADS)

    Glass, Samuel; Lawrence, Jennifer; Park, Seong-Chan; Nathanson, Gilbert

    2004-03-01

    Surfactant molecules on sulfuric acid droplets potentially alter the rates of heterogeneous reactions in the atmosphere by impeding gas entry. In previous work, we have measured the surface segregation of n-butanol and n-hexanol in sulfuric acid solutions. We have now performed molecular beam experiments with deuterated sulfuric acid solutions (60, 64, and 68 wt % D_2SO4 at 213 K) at concentrations of butanol from 0-1 M and of hexanol from 0-0.1 M. We direct a beam of a protic gas HX (X = Cl or Br) at a continuously renewed film of supercooled D_2SO_4/D_2O in vacuum and measure the fraction of thermalized HX which undergo HX→ DX exchange. Our results contradict the notion that surfactants impede gas transport. The presence of surface butanol or hexanol does not alter the rate of D_2O evaporation from the liquid surface. Our most striking result is that surface alcohol actually increases the HX→ DX exchange fraction, implying that HX dissociates more readily at the interface when alcohol is present. This enhancement may be caused by the dilution of the acid near the surface by segregated alcohol molecules, which provide additional OH groups for protonation by HX.

  1. Development of real-time radioisotope imaging systems for plant nutrient uptake studies

    PubMed Central

    Kanno, Satomi; Yamawaki, Masato; Ishibashi, Hiroki; Kobayashi, Natsuko I.; Hirose, Atsushi; Tanoi, Keitaro; Nussaume, Laurent; Nakanishi, Tomoko M.

    2012-01-01

    Ionic nutrition is essential for plant development. Many techniques have been developed to image and (or) measure ionic movement in plants. Nevertheless, most of them are destructive and limit the analysis. Here, we present the development of radioisotope imaging techniques that overcome such restrictions and allow for real-time imaging of ionic movement. The first system, called macroimaging, was developed to visualize and measure ion uptake and translocation between organs at a whole-plant scale. Such a device is fully compatible with illumination of the sample. We also modified fluorescent microscopes to set up various solutions for ion uptake analysis at the microscopic level. Both systems allow numerical analysis of images and possess a wide dynamic range of detection because they are based on radioactivity. PMID:22527392

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

    SciTech Connect

    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 exposure 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.

  3. RAI Thyroid Bed Uptake After Total Thyroidectomy: A Novel SPECT-CT Anatomic Classification System

    PubMed Central

    Zeuren, Rebecca; Biagini, Agnese; Grewal, Ravinder K.; Randolph, Gregory W.; Kamani, Dipti; Sabra, Mona M.; Shaha, Ashok R.; Tuttle, R. Michael

    2016-01-01

    Objective Recent, more selective use of radioactive iodine (RAI) has led to reevaluation of the clinical importance of achieving complete total thyroidectomy with minimal residual normal thyroid tissue. We utilize the improved localization by post-RAI remnant ablation, single photon emission computerized tomography-computed tomography (SPECT-CT) to define specific anatomic sites of residual RAI-uptake foci after total thyroidectomy for differentiated thyroid cancer (DTC) and to provide a novel classification system relating uptake to thyroid anatomy and preservation of adjacent neural structures. Study Design Retrospective. Method Radioactive iodine-uptake foci in thyroid bed were localized by SPECT/CT imaging at the time of RAI remnant ablation in 141 DTC patients undergoing total thyroidectomy. Results Minimal residual RAI uptake (median 0.32% at 24 hours) in the thyroid bed was detected by diagnostic planar whole body scans in 93% and by posttherapy SPECT/CT imaging in 99% of subjects. Discrete RAI uptake foci were identified on the SPECT/CT imaging at Berry’s ligament (87%), at superior thyroid poles (79%), in paratracheal-lobar regions (67%), in isthmus-region (54%), and in pyramidal lobe (46%). Despite the residual foci, the nonstimulated thyroglobulin (Tg) prior to remnant ablation (with a median thyroid-stimulating hormone of 0.36 m IU/L) was <0.6 ng/mL in 53% and <1 ng/mL in 73% of cases. Conclusion After extracapsular total thyroidectomy, highly sensitive detection tools identify microscopic residual RAI avid foci in thyroid bed in the majority of patients. These foci can be classified as 1) neural-related and 2) capsule-related. These common residual foci have no relationship to postoperative Tg, suggesting that attempts at radical removal of thyroid tissue in these locations may not be warranted. PMID:25891354

  4. Hypertonic upregulation of amino acid transport system A in vascular smooth muscle cells.

    PubMed

    Chen, J G; Klus, L R; Steenbergen, D K; Kempson, S A

    1994-08-01

    The A10 line of vascular smooth muscle cells has Na+ dependent transport systems for alanine, proline, and Pi, whereas uptake of leucine, myo-inositol and D-glucose is Na+ independent. When A10 cells were incubated for 4 h in medium made hypertonic by addition of sucrose, there was a marked increase in Na(+)-dependent transport of alanine and proline but no change in Na(+)-dependent Pi uptake or Na(+)-independent uptake of leucine and inositol. Intracellular alanine content was increased 61% by the hypertonic treatment. Other nonpenetrating solutes, such as cellobiose and mannitol, reproduced the effect of sucrose, but urea, a penetrating solute, did not. Studies with 2-(methylamino)-isobutyric acid revealed that the upregulation by hypertonicity involved only system A. Increases in alanine and proline uptake also occurred after incubating the cells in isotonic medium containing 0.1 mM ouabain, suggesting that an increase in intracellular Na+ may be part of the intracellular signal for upregulation of system A. Hypertonic upregulation of Na(+)-dependent alanine transport occurred also in primary cultures of vascular smooth muscle cells. The response was blocked by actinomycin D and cycloheximide, indicating that gene transcription and protein synthesis play important roles in the mechanism leading to increased alanine uptake. We conclude that vascular smooth muscle cells, during prolonged hypertonic stress, activate system A and accumulate specific neutral amino acids which may act as organic osmolytes to help maintain normal cell volume. PMID:8074188

  5. Plant uptake of cadmium from acid-extracted anaerobically digested sewage sludge. [Beta vulgaris

    SciTech Connect

    Logan, T.J.; Feltz, R.E.

    1985-01-01

    Approximately 80% of the Cd in an anaerobically digested sewage sludge was removed by acid extraction and dewatering. The acid extracted sludge was treated by (i) neutralization to pH 5.9 with Ca(OH)/sub 2/, (ii) addition of monocalcium phosphate (MCP) followed by Ca(OH)/sub 2/ neutralization to pH 5.9, and, (iii) addition of rock phosphate (RP) followed by Ca(OH)/sub 2/ neutralization to pH 5.9. The three treated sludges and the non acid-extracted sludge were applied to Spinks loamy sand at rates equivalent to 18.7 and 37.4 ..mu..mol Cd kg/sup -1/. Swiss chard (Beta vulgaris) was grown in the greenhouse for 56 d. Cadmium, Fe, Ca, and P were measured in saturation extracts of treated soil after sludge addition. These data indicated that hydroxyapatite was stable throughout the study in the soil receiving MCP treated sludge but not in other soil treatments. Cadmium concentration in saturation extracts of the soil with MCP sludge decreased while Cd concentration in saturation extracts of the other sludge treatments were much higher throughout the study. Chard yields were higher in the control than in any of the sludge treatments, and the difference was attributed to greater N availability in the control. Cadmium concentration in Swiss chard tissue at harvest was significantly lower from the MCP sludge than from the other sludges. Cadmium concentration in chard tissue was also higher from the aerated sludge (11.9 mmol Cd kg/sup -1/) than from the three acid-extracted sludges (2.58-3.29 mmol Cd kg/sup -1/). No significant difference in the Cd concentration of chard was obtained for the 18.7 and 37.4 ..mu..mol Cd kg/sup -1/ rates of the MCP sludge, while Cd concentrations in chard increased linearly with Cd applied by the other sludges.

  6. Generation, Release, and Uptake of the NAD Precursor Nicotinic Acid Riboside by Human Cells.

    PubMed

    Kulikova, Veronika; Shabalin, Konstantin; Nerinovski, Kirill; Dölle, Christian; Niere, Marc; Yakimov, Alexander; Redpath, Philip; Khodorkovskiy, Mikhail; Migaud, Marie E; Ziegler, Mathias; Nikiforov, Andrey

    2015-11-01

    NAD is essential for cellular metabolism and has a key role in various signaling pathways in human cells. To ensure proper control of vital reactions, NAD must be permanently resynthesized. Nicotinamide and nicotinic acid as well as nicotinamide riboside (NR) and nicotinic acid riboside (NAR) are the major precursors for NAD biosynthesis in humans. In this study, we explored whether the ribosides NR and NAR can be generated in human cells. We demonstrate that purified, recombinant human cytosolic 5'-nucleotidases (5'-NTs) CN-II and CN-III, but not CN-IA, can dephosphorylate the mononucleotides nicotinamide mononucleotide and nicotinic acid mononucleotide (NAMN) and thus catalyze NR and NAR formation in vitro. Similar to their counterpart from yeast, Sdt1, the human 5'-NTs require high (millimolar) concentrations of nicotinamide mononucleotide or NAMN for efficient catalysis. Overexpression of FLAG-tagged CN-II and CN-III in HEK293 and HepG2 cells resulted in the formation and release of NAR. However, NAR accumulation in the culture medium of these cells was only detectable under conditions that led to increased NAMN production from nicotinic acid. The amount of NAR released from cells engineered for increased NAMN production was sufficient to maintain viability of surrounding cells unable to use any other NAD precursor. Moreover, we found that untransfected HeLa cells produce and release sufficient amounts of NAR and NR under normal culture conditions. Collectively, our results indicate that cytosolic 5'-NTs participate in the conversion of NAD precursors and establish NR and NAR as integral constituents of human NAD metabolism. In addition, they point to the possibility that different cell types might facilitate each other's NAD supply by providing alternative precursors. PMID:26385918

  7. Endothelial lipase modulates pressure overload-induced heart failure through alternative pathway for fatty acid uptake.

    PubMed

    Nakajima, Hideto; Ishida, Tatsuro; Satomi-Kobayashi, Seimi; Mori, Kenta; Hara, Tetsuya; Sasaki, Naoto; Yasuda, Tomoyuki; Toh, Ryuji; Tanaka, Hidekazu; Kawai, Hiroya; Hirata, Ken-ichi

    2013-05-01

    Lipoprotein lipase has been considered as the only enzyme capable of generating lipid-derived fatty acids for cardiac energy. Endothelial lipase is another member of the triglyceride lipase family and hydrolyzes high-density lipoproteins. Although endothelial lipase is expressed in the heart, its function remains unclear. We assessed the role of endothelial lipase in the genesis of heart failure. Pressure overload-induced cardiac hypertrophy was generated in endothelial lipase(-/-) and wild-type mice by ascending aortic banding. Endothelial lipase expression in cardiac tissues was markedly elevated in the early phase of cardiac hypertrophy in wild-type mice, whereas lipoprotein lipase expression was significantly reduced. Endothelial lipase(-/-) mice showed more severe systolic dysfunction with left-ventricular dilatation compared with wild-type mice in response to pressure overload. The expression of mitochondrial fatty acid oxidation-related genes, such as carnitine palmitoyltransferase-1 and medium-chain acyl coenzyme A dehydrogenase, was significantly lower in the heart of endothelial lipase(-/-) mice than in wild-type mice. Also, endothelial lipase(-/-) mice had lower myocardial adenosine triphosphate levels than wild-type mice after aortic banding. In cultured cardiomyocytes, endothelial lipase was upregulated by inflammatory stimuli, whereas lipoprotein lipase was downregulated. Endothelial lipase-overexpression in cardiomyocytes resulted in an upregulation of fatty acid oxidation-related enzymes and intracellular adenosine triphosphate accumulation in the presence of high-density lipoprotein. Endothelial lipase may act as an alternative candidate to provide fatty acids to the heart and regulate cardiac function. This effect seemed relevant particularly in the diseased heart, where lipoprotein lipase action is downregulated. PMID:23460280

  8. Reactivity of fluoride dentifrices with artificial caries. III. Quantitative aspects of acquired acid resistance (AAR): F uptake, retention, surface hardening and remineralization.

    PubMed

    White, D J

    1991-01-01

    A pH cycling remineralization/dimineralization model has been used to compare remineralization and acid resistance benefits provided by commercial MFP and NaF dentifrices. Test results show that fluoride dentifrice systems were effective in enhancing lesion remineralization and providing acquired acid resistance (AAR) to carious lesions, with AAR benefits considerably greater in magnitude. Fluoride uptake into the carious lesions was associated with remineralization and AAR benefits. Dentifrices containing the highest levels of soluble ionic fluoride were found most effective in this protocol with MFP dentifrices showing significantly less activity. MFP dentifrice efficacy was enhanced slightly in calcium abrasives. The enhanced activity could be explained by increased levels of background ionic fluoride in the formulations. In contrast to the latter effects, a dual-active NaF+MFP dentifrice in a calcium abrasive system exhibited decreased efficacy relative to a silica abrasive formulation due to incompatibility of free fluoride ion. Comparison of analytical techniques for measurement of AAR in shallow lesions demonstrates that surface microhardness methods match radiographic measures and are thus adequate for ICT measurement of cariogenicity and F remineralization. PMID:1812910

  9. An updated model for nitrate uptake modelling in plants. II. Assessment of active root involvement in nitrate uptake based on integrated root system age: measured versus modelled outputs

    PubMed Central

    Malagoli, Philippe; Le Deunff, Erwan

    2014-01-01

    Background and Aims An updated version of a mechanistic structural–functional model was developed to predict nitrogen (N) uptake throughout the growth cycle by a crop of winter oilseed rape, Brassica napus, grown under field conditions. Methods The functional component of the model derives from a revisited conceptual framework that combines the thermodynamic Flow–Force interpretation of nitrate uptake isotherms and environmental and in planta effects on nitrate influx. Estimation of the root biomass (structural component) is based upon a combination of root mapping along the soil depth profile in the field and a relationship between the specific root length and external nitrate concentration. The root biomass contributing actively to N uptake was determined by introduction of an integrated root system age that allows assignment of a root absorption capacity at a specific age of the root. Key Results Simulations were well matched to measured data of N taken up under field conditions for three levels of N fertilization. The model outputs indicated that the two topsoil layers (0–30 and 30–60 cm) contained 75–88 % of the total root length and biomass, and accounted for 90–95 % of N taken up at harvest. Conclusions This conceptual framework provides a model of nitrate uptake that is able to respond to external nitrate fluctuations at both functional and structural levels. PMID:24709791

  10. An updated model for nitrate uptake modelling in plants. II. Assessment of active root involvement in nitrate uptake based on integrated root system age: measured versus modelled outputs.

    PubMed

    Malagoli, Philippe; Le Deunff, Erwan

    2014-05-01

    Background and Aims An updated version of a mechanistic structural-functional model was developed to predict nitrogen (N) uptake throughout the growth cycle by a crop of winter oilseed rape, Brassica napus, grown under field conditions. Methods The functional component of the model derives from a revisited conceptual framework that combines the thermodynamic Flow-Force interpretation of nitrate uptake isotherms and environmental and in planta effects on nitrate influx. Estimation of the root biomass (structural component) is based upon a combination of root mapping along the soil depth profile in the field and a relationship between the specific root length and external nitrate concentration. The root biomass contributing actively to N uptake was determined by introduction of an integrated root system age that allows assignment of a root absorption capacity at a specific age of the root. Key Results Simulations were well matched to measured data of N taken up under field conditions for three levels of N fertilization. The model outputs indicated that the two topsoil layers (0-30 and 30-60 cm) contained 75-88 % of the total root length and biomass, and accounted for 90-95 % of N taken up at harvest. Conclusions This conceptual framework provides a model of nitrate uptake that is able to respond to external nitrate fluctuations at both functional and structural levels. PMID:24709791

  11. Characterization of Iron Uptake from Ferrioxamine B by Chlorella vulgaris

    PubMed Central

    Allnutt, F. C. Thomas; Bonner, Walter D.

    1987-01-01

    Iron uptake from two Fe3+-hydroxamate siderophores, ferrioxamine B and Fe3+-rhodotorulate, by iron-stressed Chlorella vulgaris (ATCC strain 11468) was evaluated with some comparison to iron uptake from synthetic and organic acid ferric chelates. Iron-stress induced iron uptake from ferrioxamine B. Dissipation of the electrochemical gradient, via uncouplers, inhibited iron uptake. Respiratory inhibitors gave variable results, an indication that a direct link to respiration was not apparent. Vanadate inhibition of iron uptake indicated that an ATPase or phosphate intermediate could be involved in the uptake mechanism. Divalent cations manifested variable effects dependent on the cation and chelator used. These data confirm that C. vulgaris has an inducible iron-uptake system for Fe3+-hydroxamic acid siderophores which may involve a different mechanism than that observed for other chelates. PMID:16665771

  12. [sup 90]Y-labeled antibody uptake by human tumor xenografts and the effect of systemic administration of EDTA

    SciTech Connect

    Rowlinson-Busza, G.; Snook, D.; Epenetos, A.A. )

    1994-03-30

    A human tumor xenograft model was used to compare the tumor and normal tissue uptake of a tumor-associated monoclonal antibody radiolabeled with [sup 125]I or [sup 90]Y. Nude mice bearing SC xenografts of the human colon adenocarcinoma, HT29, were injected with a mixture of [sup 125]I- and [sup 90]Y-DTPA-labeled AUA1 monoclonal antibody, which recognizes an antigen expressed on the surface of the tumor cells. In addition, the effect of systemic ethylenediaminetetraacetic acid (EDTA) administration on [sup 90]Y-labeled antibody clearance, tumor uptake of antibody and bone accumulation of [sup 90]Y was studied in a nude mouse model of intraperitoneal cancer. Both the absolute amount (%id[center dot]g[sup -1]) and the tumor:normal tissue ratios were superior for the [sup 90]Y-labeled antibody, compared with the iodinated antibody, with the notable exception of bone. These results suggest that [sup 90]Y is a preferable isotope to iodine for radioimmunotherapy of solid masses, but that myelotoxicity due to bone uptake of released [sup 90]Y will limit the radiation dose which can be given when DTPA is used to chelate the [sup 90]Y. The [sup 90]Y-labeled antibody showed similar serum stability in vitro in the presence or absence of EDTA after incubation for up to 48 h. In vivo, urine excretion of [sup 90]Y was significantly enhanced in mice receiving daily injections of 20 mg EDTA for 3 days, commencing 2 h after intraperitoneal antibody administration, compared with control mice. There was no significant difference in the tumor uptake of [sup 90]Y-labeled antibody in EDTA-treated and control mice at any time-point up to 9 days postinjection. However, the bone levels of [sup 90]Y were significantly reduced in EDTA-treated mice at all times from 1 to 9 days. Based on these results, it should be possible to increase the amount of [sup 90]Y-labeled antibody administered, by chelating the released [sup 90]Y with systemic EDTA to facilitate its excretion. 50 refs., 5 figs.

  13. Light-Activated Amino Acid Transport Systems in Halobacterium halobium Envelope Vesicles: Role of Chemical and Electrical Gradients

    NASA Technical Reports Server (NTRS)

    MacDonald, Russell E.; Greene, Richard V.; Lanyi, Janos K.

    1977-01-01

    The accumulation of 20 commonly occurring L-amino acids by cell envelope vesicles of Halobacterium halobium, in response to light-induced membrane potential and an artificially created sodium gradient, has been studied. Nineteen of these amino acids are actively accumulated under either or both of these conditions. Glutamate is unique in that its uptake is driven only by a chemical gradient for sodium. Amino acid concentrations at half-maximal uptake rates (Km) and maximal transport rates (V(sub max) have been determined for the uptake of all 19 amino acids. The transport systems have been partially characterized with respect to groups of amino acids transported by common carriers, cation effects, and relative response to the electrical and chemical components of the sodium gradient, the driving forces for uptake. The data presented clearly show that the carrier systems, which are responsible for uptake of individual amino acids, are as variable in their properties as those found in other organisms, i. e., some are highly specific for individual amino acids, some transport several amino acids competitively, some are activated by a chemical gradient of sodium only, and some function also in the complete absence of such a gradient. For all amino acids, Na(+) and K(+) are both required for maximal rate of uptake. The carriers for L-leucine and L-histidine are symmetrical in that these amino acids are transported in both directions across the vesicle membrane. It is suggested that coupling of substrate transport to metabolic energy via transient ionic gradients may be a general phenomenon in procaryotes.

  14. Uptake of (N-Me-3H)-choline by synaptosomes from the central nervous system of Locusta migratoria

    SciTech Connect

    Breer, H.

    1982-03-01

    The accumulation of 3H-choline by isolated synaptosomes from the central nervous system of locust was studied at concentrations varying from 0.05 to 40 microM. Kinetic analysis of the saturable process revealed a high-affinity and a low-affinity system. The high-affinity uptake was competitively inhibited by hemicholinium-3 and was absolutely dependent on external sodium. Elevated potassium concentrations inhibited choline uptake. The choline uptake by insect synaptosomes was found to be remarkably resistant to a variety of metabolic inhibitors. The reduced choline uptake under depolarizing conditions (high potassium concentration or veratridine) in the absence of calcium implies that electrochemical gradients are important for high-affinity choline uptake. Depolarization of preloaded synaptosomes under appropriate conditions resulted in a significant release of newly accumulated choline radioactivity.

  15. The mechanisms of North Atlantic CO2 uptake in a large Earth System Model ensemble

    NASA Astrophysics Data System (ADS)

    Halloran, P. R.; Booth, B. B. B.; Jones, C. D.; Lambert, F. H.; McNeall, D. J.; Totterdell, I. J.; Völker, C.

    2015-07-01

    The oceans currently take up around a quarter of the carbon dioxide (CO2) emitted by human activity. While stored in the ocean, this CO2 is not influencing Earth's radiation budget; the ocean CO2 sink therefore plays an important role in mitigating global warming. CO2 uptake by the oceans is heterogeneous, with the subpolar North Atlantic being the strongest CO2 sink region. Observations over the last 2 decades have indicated that CO2 uptake by the subpolar North Atlantic sink can vary rapidly. Given the importance of this sink and its apparent variability, it is critical that we understand the mechanisms behind its operation. Here we explore the combined natural and anthropogenic subpolar North Atlantic CO2 uptake across a large ensemble of Earth System Model simulations, and find that models show a peak in sink strength around the middle of the century after which CO2 uptake begins to decline. We identify different drivers of change on interannual and multidecadal timescales. Short-term variability appears to be driven by fluctuations in regional seawater temperature and alkalinity, whereas the longer-term evolution throughout the coming century is largely occurring through a counterintuitive response to rising atmospheric CO2 concentrations. At high atmospheric CO2 concentrations the contrasting Revelle factors between the low latitude water and the subpolar gyre, combined with the transport of surface waters from the low latitudes to the subpolar gyre, means that the subpolar CO2 uptake capacity is largely satisfied from its southern boundary rather than through air-sea CO2 flux. Our findings indicate that: (i) we can explain the mechanisms of subpolar North Atlantic CO2 uptake variability across a broad range of Earth System Models; (ii) a focus on understanding the mechanisms behind contemporary variability may not directly tell us about how the sink will change in the future; (iii) to identify long-term change in the North Atlantic CO2 sink we should focus

  16. The mechanisms of North Atlantic CO2 uptake in a large Earth System Model ensemble

    NASA Astrophysics Data System (ADS)

    Halloran, P. R.; Booth, B. B. B.; Jones, C. D.; Lambert, F. H.; McNeall, D. J.; Totterdell, I. J.; Völker, C.

    2014-10-01

    The oceans currently take up around a quarter of the carbon dioxide (CO2) emitted by human activity. While stored in the ocean, this CO2 is not influencing Earth's radiation budget; the ocean CO2 sink therefore plays an important role in mitigating global warming. CO2 uptake by the oceans is heterogeneous, with the subpolar North Atlantic being the strongest CO2 sink region. Observations over the last two decades have indicated that CO2 uptake by the subpolar North Atlantic sink can vary rapidly. Given the importance of this sink and its apparent variability, it is critical that we understand the mechanisms behind its operation. Here we explore subpolar North Atlantic CO2 uptake across a large ensemble of Earth System Model simulations, and find that models show a peak in sink strength around the middle of the century after which CO2 uptake begins to decline. We identify different drivers of change on interannual and multidecadal timescales. Short-term variability appears to be driven by fluctuations in regional seawater temperature and alkalinity, whereas the longer-term evolution throughout the coming century is largely occurring through a counterintuitive response to rising atmospheric CO2 concentrations. At high atmospheric CO2 concentrations the contrasting Ravelle factors between the subtropical and subpolar gyres, combined with the transport of surface waters from the subtropical to subpolar gyre, means that the subpolar CO2 uptake capacity is largely satisfied from its southern boundary rather than through air-sea CO2 flux. Our findings indicate that: (i) we can explain the mechanisms of subpolar North Atlantic CO2 uptake variability across a broad range of Earth System Models, (ii) a focus on understanding the mechanisms behind contemporary variability may not directly tell us about how the sink will change in the future, (iii) to identify long-term change in the North Atlantic CO2 sink we should focus observational resources on monitoring subtropical as

  17. Uptake of algal carbon and the synthesis of an "essential" fatty acid by Uvigerina ex. gr. semiornata (Foraminifera) within the Pakistan margin oxygen minimum zone: evidence from fatty acid biomarker and 13C tracer experiments

    NASA Astrophysics Data System (ADS)

    Larkin, K. E.; Gooday, A. J.; Woulds, C.; Jeffreys, R.; Schwartz, M.; Cowie, G.; Whitcraft, C.; Levin, L.; Dick, J. R.; Pond, D. W.

    2014-01-01

    Foraminifera are an important component of benthic communities in oxygen depleted settings, where they potentially play a~significant role in the processing of organic matter. We tracked the uptake of a 13C-labeled algal food source into individual fatty acids in the benthic foraminiferal species, Uvigerina ex. gr. semiornata, from the Arabian Sea oxygen minimum zone (OMZ). The tracer experiments were conducted on the Pakistan Margin during the late/post monsoon period (August-October 2003). A monoculture of the diatom Thalassiosira weisflogii was 13C-labeled and used to simulate a pulse of phytoplankton in two complementary experiments. A lander system was used for in situ incubations at 140 m and for 2.5 days duration, whilst a laboratory incubation used an oxystat system to maintain ambient dissolved oxygen concentrations. These shipboard experiments were terminated after 5 days. Uptake of diatoms was rapid, with high incorporation of diatom fatty acids into foraminifera after ~2 days in both experiments. Ingestion of the diatom food source was indicated by the increase over time in the quantity of diatom biomarker fatty acids in the foraminifera and by the high percentage of 13C in many of the fatty acids present at the endpoint of both in~situ and laboratory-based experiments. These results indicate that U. ex. gr. semiornata rapidly ingested the diatom food source and that this foraminifera will play an important role in the short-term cycling of organic matter within this OMZ environment. The experiments also suggested that U. ex. gr. semiornata consumed non-labeled bacterial food items, particularly bacteria, and synthesised the polyunsaturated fatty acid 20:4(n-6) de novo. 20:4(n-6) is often abundant in benthic fauna yet its origins and function have remained unclear. This study demonstrates that U. ex. gr. semiornata is capable of de novo synthesis of this "essential fatty acid" and is potentially a major source of this dietary nutrient in benthic food

  18. Hepatocellular uptake of oleate is energy dependent, sodium linked, and inhibited by an antibody to a hepatocyte plasma membrane fatty acid binding protein.

    PubMed Central

    Stremmel, W; Strohmeyer, G; Berk, P D

    1986-01-01

    Several studies suggest that a portion of hepatocellular nonesterified fatty acid uptake may be carrier mediated. To further investigate this process, initial rates (Vo) of [14C]oleate uptake into rat hepatocytes, isolated by collagenase perfusion and incubated at 37 degrees C with oleate in the presence of bovine serum albumin, were studied as a function of the concentration of unbound [14C]oleate in the medium. Vo was saturable with increasing unbound oleate concentration (Km = 8.3 X 10(-8) M; Vmax = 197 pmol per min per 5 X 10(4) hepatocytes) and was not inhibited by up to 40 microM sulfobromophthalein, taurocholate, or cholic acid. Oleate uptake was sodium dependent. Vo was significantly diminished when Li+, K+, choline, or sucrose were substituted for Na+ in the incubation medium and was reduced 46% by 1 mM ouabain. Uptake was also markedly reduced after exposure of cells to metabolic inhibitors (e.g., 2,4-dinitrophenol, carbonyl cyanide m-chlorophenylhydrazone, antimycin, KCN). To evaluate the physiologic significance of the previously isolated rat liver plasma membrane fatty acid-binding protein, the effect of an antibody directed against this protein on hepatocellular [14C]oleate uptake was examined. Preincubation of hepatocytes with the IgG fraction of this antiserum inhibited Vo of [14C]oleate by up to 65% in dose-related fashion, without altering Vo for [35S]sulfobromophthalein, [14C]taurocholate, or [3H]cholate. These data indicate that at least a portion of hepatocellular oleate uptake is energy dependent, sodium linked, and mediated by a specific liver plasma membrane-fatty acid-binding protein. PMID:3459144

  19. Lack of effect of entorhinal kindling on L-(/sup 3/H)glutamic acid presynaptic uptake and postsynaptic binding in hippocampus

    SciTech Connect

    Slevin, J.T.; Ferrara, L.P.

    1985-07-01

    Sodium-independent L-(/sup 3/H)glutamic acid binding and sodium-dependent L-(/sup 3/H)glutamic acid high affinity uptake were measured in hippocampal membranes of rats administered electroshock seizures or kindled to class 5 seizures by entorhinal cortical stimulation. There were no differences in these glutamatergic synaptic markers among electroshocked, kindled, or surgical control animals. Entorhinal kindling is not a reflection of activity-regulated facilitation of perforant path glutamatergic neurotransmission.

  20. Efficient Docosahexaenoic Acid Uptake by the Brain from a Structured Phospholipid.

    PubMed

    Hachem, Mayssa; Géloën, Alain; Van, Amanda Lo; Foumaux, Baptiste; Fenart, Laurence; Gosselet, Fabien; Da Silva, Pedro; Breton, Gildas; Lagarde, Michel; Picq, Madeleine; Bernoud-Hubac, Nathalie

    2016-07-01

    Docosahexaenoic acid (DHA) is the main essential omega-3 fatty acid in brain tissues required for normal brain development and function. An alteration of brain DHA in neurodegenerative diseases such as Alzheimer's and Parkinson's is observed. Targeted intake of DHA to the brain could compensate for these deficiencies. Blood DHA is transported across the blood-brain barrier more efficiently when esterified at the sn-2 position of lyso-phosphatidylcholine. We used a structured phosphatidylcholine to mimic 2-docosahexaenoyl-lysoPC (lysoPC-DHA), named AceDoPC (1-acetyl,2-docosahexaenoyl-glycerophosphocholine), that may be considered as a stabilized form of the physiological lysoPC-DHA and that is neuroprotective in experimental ischemic stroke. The aim of the present study was to investigate whether AceDoPC is a relevant delivery form of DHA to the brain in comparison with other forms of the fatty acid. By combining in vitro and in vivo experiments, our findings report for the first time that AceDoPC is a privileged and specific carrier of DHA to the brain, when compared with DHA-containing PC and non-esterified DHA. We also show that AceDoPC was hydrolyzed, in part, into lysoPC-DHA. Ex vivo autoradiography of rat brain reveals that DHA from AceDoPC was localized in specific brain regions playing key roles in memory, thoughts, and cognitive functions. Finally, using molecular modeling approaches, we demonstrate that electrostatic and lipophilic potentials are distributed very similarly at the surfaces of AceDoPC and lysoPC-DHA. Our findings identify AceDoPC as an efficient way to specifically target DHA to the brain, which would allow potential preventive and therapeutic approaches for neurological diseases. PMID:26041661

  1. Eco-Hydro-Connectivity: Tracking the Diurnal Signal of Plant Water Uptake through the Hydrologic System

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Plant water uptake during summer is characterized by strong diurnal fluctuations. As a result a diurnal sink term is imposed on catchment storage, affecting the unsaturated zone, sometimes the saturated zone and even streamflow. Detecting this signal and understanding its propagation through the hydrological system may help to better quantify eco-hydrological connectivity. The extent and strength of the propagation of this signal from plant to soil to ground- and streamwater was investigated with a unique setup of 46 field sites in Luxemburg and 15 field sites in Germany. These sites cover a range of geologies, soils, topographies and types of vegetation. Vegetation types include grassland, pine forest (young and old) and different deciduous forest stands. Available data at all sites includes information at high temporal resolution from 3-5 soil moisture profiles, matrix potential, piezometers and sapflow sensors (as proxy for plant water uptake) as well as standard climate data. At sites with access to a stream, discharge or water level is also recorded. Signal strength (amplitude of diurnal fluctuations) can thus be traced through the system and gives an indication of the physical sphere of influence of plant water uptake i.e. the "eco-hydro-connectivity". The analysis of time lags (or phase shifts) between daily fluctuations in temperature, radiation, sapflow, soil water, groundwater and streamflow gives further insights into the processes driving and propagating these signals and inter-site comparison allows for the investigation of local controls.

  2. Tracking the diurnal signal of plant water uptake through the hydrologic system

    NASA Astrophysics Data System (ADS)

    Blume, Theresa; Hassler, Sibylle; Heidbüchel, Ingo; Weiler, Markus; Simard, Sonia; Güntner, Andreas; Heinrich, Ingo

    2015-04-01

    Plant water uptake during summer is characterized by strong diurnal fluctuations. As a result a diurnal sink term is imposed on catchment storage, affecting the unsaturated zone, sometimes the saturated zone and even streamflow. Detecting this signal and understanding its propagation through the hydrological system may help to better quantify eco-hydrological connectivity. The extent and strength of the propagation of this signal from plant to soil to ground- and stream water was investigated with a unique setup of 46 field sites in Luxemburg and 15 field sites in Germany. These sites cover a range of geologies, soils, topographies and types of vegetation. Vegetation types include grassland, pine forest (young and old) and different deciduous forest stands. Available data at all sites includes information at high temporal resolution from 3-5 soil moisture profiles, matrix potential, piezometers and sapflow sensors (as proxy for plant water uptake) as well as standard climate data. At sites with access to a stream, discharge or water level is also recorded. Signal strength (amplitude of diurnal fluctuations) can thus be traced through the system and gives an indication of the physical sphere of influence of plant water uptake i.e. the "eco-hydro-connectivity". Temporal dynamics of signal strength furthermore suggest a shifting spatial distribution of root water uptake with time. The analysis of time lags (or phase shifts) between daily fluctuations in temperature, radiation, sapflow, soil water, groundwater and streamflow gives further insights into the processes driving and propagating these signals and inter-site comparison allows for the investigation of local controls.

  3. Factors Influencing the Diversity of Iron Uptake Systems in Aquatic Microorganisms

    PubMed Central

    Desai, Dhwani K.; Desai, Falguni D.; LaRoche, Julie

    2012-01-01

    Iron (Fe) is an essential micronutrient for many processes in all living cells. Dissolved Fe (dFe) concentrations in the ocean are of the order of a few nM, and Fe is often a factor limiting primary production. Bioavailability of Fe in aquatic environments is believed to be primarily controlled through chelation by Fe-binding ligands. Marine microbes have evolved different mechanisms to cope with the scarcity of bioavailable dFe. Gradients in dFe concentrations and diversity of the Fe-ligand pool from coastal to open ocean waters have presumably imposed selection pressures that should be reflected in the genomes of microbial communities inhabiting the pelagic realm. We applied a hidden Markov model (HMM)-based search for proteins related to cellular iron metabolism, and in particular those involved in Fe uptake mechanisms in 164 microbial genomes belonging to diverse taxa and occupying different aquatic niches. A multivariate statistical approach demonstrated that in phototrophic organisms, there is a clear influence of the ecological niche on the diversity of Fe uptake systems. Extending the analyses to the metagenome database from the Global Ocean Sampling expedition, we demonstrated that the Fe uptake and homeostasis mechanisms differed significantly across marine niches defined by temperatures and dFe concentrations, and that this difference was linked to the distribution of microbial taxa in these niches. Using the dN/dS ratios (which signify the rate of non-synonymous mutations) of the nucleotide sequences, we identified that genes encoding for TonB, Ferritin, Ferric reductase, IdiA, ZupT, and Fe2+ transport proteins FeoA and FeoB were evolving at a faster rate (positive selection pressure) while genes encoding ferrisiderophore, heme and Vitamin B12 uptake systems, siderophore biosynthesis, and IsiA and IsiB were under purifying selection pressure (evolving slowly). PMID:23087680

  4. Dust Modeling with GEOS-Chem: Evidence for Acidic Uptake on Dust Surfaces during INTEX-B

    NASA Technical Reports Server (NTRS)

    Fairlie, T. Duncan

    2007-01-01

    We use measurements of aerosol ion composition and size made from the DC8 aircraft during the 2006 INTEX-B airborne campaign to identify mineral dust signatures, and look for evidence for interaction of dust with acidic components. Coating of dust with sulfate or nitrate favors the role of dust particles as cloud condensation nucleii, can promote further uptake of SO2 and N2O5, can impact NOx/HNO3 partitioning, and can shift sulfate or nitrate towards larger sizes, affecting atmospheric lifetimes for both aerosol and gas components. Mineral dust had a pervasive presence on flights made during the Northern Pacific deployment of the INTEX-B mission. We use scatter plots of ion mixing ratios with Na+ and Ca(2+) to distinguish sea salt and mineral components of the aerosol distribution, respectively. Positive correlations of non-sea-salt sulfate and nitrate with calcium indicate that the dusty air stream is associated with polluted air masses. Sulfate-ammonium scatter plots indicate sulfate to be primarily in the form of (NH4)2SO4. A positive correlation between Ca(2+) and NO-, but little evidence of NH4NO3, suggests that NO3- may be associated with mineral dust surfaces. 3-d model simulations conducted with the GEOS-Chem chemical transport model indicate that transpacific transport from East Asia was principally responsible for the dust observed from the aircraft over the Pacific. We compare the aerosol component relationships in the model with those observed. Uptake of sulfate and nitrate on the dust is not yet represented in the model.

  5. Multifunctional Hyaluronic Acid and Chondroitin Sulfate Nanoparticles: Impact of Glycosaminoglycan Presentation on Receptor Mediated Cellular Uptake and Immune Activation.

    PubMed

    Oommen, Oommen P; Duehrkop, Claudia; Nilsson, Bo; Hilborn, Jöns; Varghese, Oommen P

    2016-08-17

    Hyaluronic acid (HA) and chondroitin sulfate (CS) polymers are extensively used for various biomedical applications, such as for tissue engineering, drug delivery, and gene delivery. Although both these biopolymers are known to target cell surface CD44 receptors, their relative cellular targeting properties and immune activation potential have never been evaluated. In this article, we present the synthesis and characterization of novel self-assembled supramolecular HA and CS nanoparticles (NPs). These NPs were developed using fluorescein as a hydrophobic component that induced amphiphilicity in biopolymers and also efficiently stabilized anticancer drug doxorubicin (DOX) promoting a near zero-order drug release. The cellular uptake and cytotoxicity studies of these NPs in different human cancer lines, namely, human colorectal carcinoma cell line HCT116 and human breast cancer cell line MCF-7 demonstrated dose dependent cytotoxicity. Interestingly, both NPs showed CD44 dependent cellular uptake with the CS-DOX NP displaying higher dose-dependent cytotoxicity than the HA-DOX NP in different mammalian cells tested. Immunological evaluation of these nanocarriers in an ex vivo human whole blood model revealed that unlike unmodified polymers, the HA NP and CS NP surprisingly showed platelet aggregation and thrombin-antithrombin complex formation at high concentrations (0.8 mg/mL). We also observed a clear difference in early- and late-stage complement activation (C3a and sC5b-9) with CS and CS NP triggering significant complement activation at high concentrations (0.08-0.8 mg/mL), unlike HA and HA NP. These results offer new insight into designing glycosaminoglycan-based NPs and understanding their hematological responses and targeting ability. PMID:27468113

  6. Carnosic acid stimulates glucose uptake in skeletal muscle cells via a PME-1/PP2A/PKB signalling axis.

    PubMed

    Lipina, Christopher; Hundal, Harinder S

    2014-11-01

    Carnosic acid (CA) is a major constituent of the labiate herbal plant Rosemary (Rosmarinus officinalis), which has been shown to exhibit a number of beneficial health properties. In particular, recently there has been growing interest into the anti-obesity effects conveyed by CA, including its ability to counteract obesity-associated hyperglycaemia and insulin resistance. However, the mechanisms underlying its anti-diabetic responses are not fully understood. In this study, we hypothesized that CA may act to improve glycaemic status through enhancing peripheral glucose clearance. Herein, we demonstrate that CA acts to mimic the metabolic actions of insulin by directly stimulating glucose uptake in rat skeletal L6 myotubes, concomitant with increased translocation of the GLUT4 glucose transporter to the plasma membrane. Mechanistically, CA-induced glucose transport was found to be dependent on protein kinase B (PKB/Akt) but not AMPK, despite both kinases being activated by CA. Crucially, in accordance with its ability to activate PKB and stimulate glucose uptake, we show that CA conveys these effects through a pathway involving PME-1 (protein phosphatase methylesterase-1), a key negative regulator of the serine/threonine phosphatase PP2A (protein phosphatase 2A). Herein, we demonstrate that CA promotes PME-1 mediated demethylation of the PP2A catalytic subunit leading to its suppressed activity, and in doing so, alleviates the repressive action of PP2A towards PKB. Collectively, our findings provide new insight into how CA may improve glucose homeostasis through enhancing peripheral glucose clearance in tissues such as skeletal muscle through a PME-1/PP2A/PKB signalling axis, thereby mitigating pathological effects associated with the hyperglycaemic state. PMID:25038454

  7. Preparation of HIFU-triggered tumor-targeted hyaluronic acid micelles for controlled drug release and enhanced cellular uptake.

    PubMed

    Zheng, Shaohui; Jin, Zhen; Han, Jiwon; Cho, Sunghoon; Nguyen, Van Du; Ko, Seong Young; Park, Jong-Oh; Park, Sukho

    2016-07-01

    In this study, a novel type of high intensity focused ultrasound (HIFU)-triggered active tumor-targeting polymeric micelle was prepared and investigated for controlled drug release and enhanced cellular uptake. Amphiphilic hyaluronic acid (HA) conjugates were synthesized to form docetaxel loaded micelles in aqueous conditions with high encapsulation efficiencies of over 80%. The micelle sizes were limited to less than 150nm, and they varied slightly according to the encapsulated drug amount. Modifying the micellar surface modification with polyethylene glycol diamine successfully inhibited premature drug leakage at a certain level, and it can be expected to prolong the circulation time of the particles in blood. In addition, high-intensity focused ultrasound was introduced to control the release of docetaxel from micelles, to which the release behavior of a drug can be tuned. The in-vitro cell cytotoxicity of docetaxel-loaded micelles was verified against CT-26 and MDA-MB-231 cells. The IC50 values of drug-loaded micelles to CT-26 and MDA-MB-231 cells were 1230.2 and 870.9ng/mL, respectively. However, when exposed to HIFU, the values decreased significantly, to 181.9 and 114.3ng/mL, suggesting that HIFU can enhance cell cytotoxicity by triggering the release of a drug from the micelles. Furthermore, cellular uptake tests were conducted via the quantitative analysis of intracellular drug concentration within CT-26 (CD44 negative), MDA-MB-231 (CD44 positive), and MDA-MB-231 (CD44 blocked), and then imaged with coumarin-6 loaded micelles. The results verified that intracellular drug delivery can be enhanced efficiently via the CD44 receptor-mediated endocytosis of HA micelles. Moreover, HIFU enhanced the cellular uptake behavior by altering the permeability of the cell membrane. It was also able to aid with the extravasation of micelles into the interior of tumors, which will be explained in further research. Therefore, the present study demonstrates that the micelles

  8. Characterization of methylaminoisobutyric acid transport by system A in rat mammary gland.

    PubMed

    Tovar, A R; Avila, E; DeSantiago, S; Torres, N

    2000-07-01

    During lactation, the mammary gland has a large demand for amino acids for the synthesis of milk proteins and fatty acids. Arteriovenous differences in amino acids across the mammary gland show an elevated uptake of small neutral amino acids that are mainly transported via system A. The purpose of this study was to characterize the transport of methylaminoisobutyric acid (MeAIB), an amino acid analog used to model transport by system A in lactating rat mammary gland explants. MeAIB accumulation in mammary gland cells increased steadily, and after 3 hours of incubation, the intracellular concentration of the analog was 8-fold higher than the concentration in the medium. MeAIB transport into mammary gland explants showed a Km of 3.3 +/- 0.4 mmol/L and a maximal velocity (Vmax) of 555 +/- 23 pmol/microL intracellular fluid (ICF) x min, indicating a system with high capacity but low affinity for its substrate. MeAIB transport into mammary tissue depended highly on Na+, and the uptake was inhibited by addition of natural and analog small neutral amino acids. Cationic, anionic, and large neutral amino acids did not reduce MeAIB transport into mammary gland explants. Preincubation of mammary gland explants in an amino acid-free medium stimulated MeAIB transport, suggesting an adaptive regulation. The addition of an equimolar mixture of alanine, glycine, and serine to the preincubation medium inhibited stimulation of MeAIB transport. Furthermore, stimulation of MeAIB uptake by amino acid starvation was also prevented by the addition of actinomycin D, cycloheximide, tunicamycin, and colchicine. Dibutyryl cyclic adenosine monophosphate (cAMP) increased MeAIB uptake, whereas phorbol 12-myristate 13-acetate (PMA) did not stimulate MeAIB transport. During the first postweaning days, kinetic analyses showed a decrease of 27% in the Vmax. Injection of rat lactating mammary gland mRNA into Xenopus laevis oocytes induced expression of the MeAIB transport system; however, the

  9. Human uptake and incorporation of an immunogenic nonhuman dietary sialic acid

    PubMed Central

    Tangvoranuntakul, Pam; Gagneux, Pascal; Diaz, Sandra; Bardor, Muriel; Varki, Nissi; Varki, Ajit; Muchmore, Elaine

    2003-01-01

    Humans are genetically unable to produce the sialic acid N-glycolylneuraminic acid (Neu5Gc), because of a mutation that occurred after our last common ancestor with great apes. Although Neu5Gc is presumed absent from normal humans, small amounts have been claimed to exist in human tumors and fetal meconium. We have generated an antibody with high specificity and avidity for Neu5Gc. Fetal tissues, normal adult tissues, and breast carcinomas from humans showed reactivity to this antibody, primarily within secretory epithelia and blood vessels. The presence of small amounts of Neu5Gc was confirmed by MS. Absent any known alternate pathway for its synthesis, we reasoned that these small amounts of Neu5Gc might originate from exogenous sources. Indeed, human cells fed with Neu5Gc incorporated it into endogenous glycoproteins. When normal human volunteers ingested Neu5Gc, a portion was absorbed and eliminated in urine, and small quantities were incorporated into newly synthesized glycoproteins. Neu5Gc has never been reported in plants or microbes to our knowledge. We found that Neu5Gc is rare in poultry and fish, common in milk products, and enriched in red meats. Furthermore, normal humans have variable amounts of circulating IgA, IgM, and IgG antibodies against Neu5Gc, with the highest levels comparable to those of the previously known anti-α-galactose xenoreactive antibodies. This finding represents an instance wherein humans absorb and metabolically incorporate a nonhuman dietary component enriched in foods of mammalian origin, even while generating xenoreactive, and potentially autoreactive, antibodies against the same molecule. Potential implications for human diseases are briefly discussed. PMID:14523234

  10. Synthetic nanoparticles camouflaged with biomimetic erythrocyte membranes for reduced reticuloendothelial system uptake.

    PubMed

    Rao, Lang; Xu, Jun-Hua; Cai, Bo; Liu, Huiqin; Li, Ming; Jia, Yan; Xiao, Liang; Guo, Shi-Shang; Liu, Wei; Zhao, Xing-Zhong

    2016-02-26

    Suppression of the reticuloendothelial system (RES) uptake is one of the most challenging tasks in nanomedicine. Coating stratagems using polymers, such as poly(ethylene glycol) (PEG), have led to great success in this respect. Nevertheless, recent observations of immunological response toward these synthetic polymers have triggered a search for better alternatives. In this work, natural red blood cell (RBC) membranes are camouflaged on the surface of Fe3O4 nanoparticles for reducing the RES uptake. In vitro macrophage uptake, in vivo biodistribution and pharmacokinetic studies demonstrate that the RBC membrane is a superior alternative to the current gold standard PEG for nanoparticle 'stealth'. Furthermore, we systematically investigate the in vivo potential toxicity of RBC membrane-coated nanoparticles by blood biochemistry, whole blood panel examination and histology analysis based on animal models. The combination of synthetic nanoparticles and natural cell membranes embodies a novel and biomimetic nanomaterial design strategy and presents a compelling property of functional materials for a broad range of biomedical applications. PMID:26820630

  11. Synthetic nanoparticles camouflaged with biomimetic erythrocyte membranes for reduced reticuloendothelial system uptake

    NASA Astrophysics Data System (ADS)

    Rao, Lang; Xu, Jun-Hua; Cai, Bo; Liu, Huiqin; Li, Ming; Jia, Yan; Xiao, Liang; Guo, Shi-Shang; Liu, Wei; Zhao, Xing-Zhong

    2016-02-01

    Suppression of the reticuloendothelial system (RES) uptake is one of the most challenging tasks in nanomedicine. Coating stratagems using polymers, such as poly(ethylene glycol) (PEG), have led to great success in this respect. Nevertheless, recent observations of immunological response toward these synthetic polymers have triggered a search for better alternatives. In this work, natural red blood cell (RBC) membranes are camouflaged on the surface of Fe3O4 nanoparticles for reducing the RES uptake. In vitro macrophage uptake, in vivo biodistribution and pharmacokinetic studies demonstrate that the RBC membrane is a superior alternative to the current gold standard PEG for nanoparticle ‘stealth’. Furthermore, we systematically investigate the in vivo potential toxicity of RBC membrane-coated nanoparticles by blood biochemistry, whole blood panel examination and histology analysis based on animal models. The combination of synthetic nanoparticles and natural cell membranes embodies a novel and biomimetic nanomaterial design strategy and presents a compelling property of functional materials for a broad range of biomedical applications.

  12. Computational screening of iodine uptake in zeolitic imidazolate frameworks in a water-containing system.

    PubMed

    Yuan, Yue; Dong, Xiuqin; Chen, Yifei; Zhang, Minhua

    2016-08-17

    Iodine capture is of great environmental significance due to the high toxicity and volatility of I2. Here we conduct a systematic computational investigation of iodine adsorption in zeolitic imidazolate frameworks (ZIFs) by adopting the grand canonical Monte Carlo (GCMC) simulation and the density functional theory (DFT) method. The results confirm the vital structural factors for iodine adsorption at 298 K and moderate pressures including metal sites, organic linkers, symmetry, and topology types. The uptake will be enhanced by active metal sites, the simple imidazolate linker and single asymmetric linkers with polar functional groups. The symmetry effect is stronger than the surface properties. Meanwhile low steric hindrance is more beneficial than polar functional groups to iodine adsorption. The specific topology types like mer bringing large surface areas and large diameter cages result in high iodine capacities. Iodine molecules tend to locate in cages with large diameters and aggregates along the sides of cages. In contrast, water prefers small diameter cages. In hydrophilic materials, water has a negative impact on iodine uptake due to its similar adsorption sites to iodine. The selectivity of iodine over water increases with increasing water content due to the large diameter cages of ZIFs. This work proves that ZIFs can be identified as efficient and economical adsorbents with high diversity for iodine in a water-containing system. Furthermore, it provides comprehensive insights into key structural factors for iodine uptake and separation in silver-free porous solids. PMID:27499079

  13. Uptake of algal carbon and the likely synthesis of an "essential" fatty acid by Uvigerina ex. gr. semiornata (Foraminifera) within the Pakistan margin oxygen minimum zone: evidence from fatty acid biomarker and 13C tracer experiments

    NASA Astrophysics Data System (ADS)

    Larkin, K. E.; Gooday, A. J.; Woulds, C.; Jeffreys, R. M.; Schwartz, M.; Cowie, G.; Whitcraft, C.; Levin, L.; Dick, J. R.; Pond, D. W.

    2014-07-01

    Foraminifera are an important component of benthic communities in oxygen-depleted settings, where they potentially play a significant role in the processing of organic matter. We tracked the uptake of a 13C-labelled algal food source into individual fatty acids in the benthic foraminiferal species Uvigerina ex. gr. semiornata from the Arabian Sea oxygen minimum zone (OMZ). The tracer experiments were conducted on the Pakistan margin during the late/post monsoon period (August-October 2003). A monoculture of the diatom Thalassiosira weisflogii was 13C-labelled and used to simulate a pulse of phytoplankton in two complementary experiments. A lander system was used for in situ incubations at 140 m water depth and for 2.5 days in duration. Shipboard laboratory incubations of cores collected at 140 m incorporated an oxystat system to maintain ambient dissolved oxygen concentrations and were terminated after 5 days. Uptake of diatoms was rapid, with a high incorporation of diatom fatty acids into foraminifera after ~ 2 days in both experiments. Ingestion of the diatom food source was indicated by the increase over time in the quantity of diatom biomarker fatty acids in the foraminifera and by the high percentage of 13C in many of the fatty acids present at the endpoint of both in situ and laboratory-based experiments. These results indicate that acid" is often abundant in benthic fauna, yet

  14. Arbuscular mycorrhizal fungi and rhizobium facilitate nitrogen uptake and transfer in soybean/maize intercropping system

    PubMed Central

    Meng, Lingbo; Zhang, Aiyuan; Wang, Fei; Han, Xiaoguang; Wang, Dejiang; Li, Shumin

    2015-01-01

    The tripartite symbiosis between legumes, rhizobia and mycorrhizal fungi are generally considered to be beneficial for the nitrogen (N) uptake of legumes, but the facilitation of symbiosis in legume/non-legume intercropping systems is not clear. Therefore, the aims of the research are as follows: (1) to verify if the dual inoculation can facilitate the N uptake and N transfer in maize/soybean intercropping systems and (2) to calculate how much N will be transferred from soybean to maize. A pot experiment with different root separations [solid barrier, mesh (30 μm) barrier and no barrier] was conducted, and the 15N isotopic tracing method was used to calculate how much N transferred from soybean to maize inoculated with arbuscular mycorrhizal fungi (AMF) and rhizobium in a soybean (Glycine max L.cv. Dongnong No. 42)/maize (Zea mays L.cv. Dongnong No. 48) intercropping system. Compared with the Glomus mosseae inoculation (G.m.), Rhizobium SH212 inoculation (SH212), no inoculation (NI), the dual inoculation (SH212+G.m.) increased the N uptake of soybean by 28.69, 39.58, and 93.07% in a solid barrier system. N uptake of maize inoculated with both G. mosseae and rhizobium was 1.20, 1.28, and 1.68 times more than that of G.m., SH212 and NI, respectively, in solid barrier treatments. In addition, the amount of N transferred from soybean to maize in a dual inoculation system with a mesh barrier was 7.25, 7.01, and 11.45 mg more than that of G.m., SH212 and NI and similarly, 6.40, 7.58, and 12.46 mg increased in no barrier treatments. Inoculating with both AMF and rhizobium in the soybean/maize intercropping system improved the N fixation efficiency of soybean and promoted N transfer from soybean to maize, resulting in the improvement of yield advantages of legume/non-legume intercropping. PMID:26029236

  15. Cell Permeability: a Factor in the Biotin-Oleate Relationship in Lactobacillus arabinosus II. Effect of Oleic Acid and Other Surfactants on Free Biotin Uptake

    PubMed Central

    Waller, James R.; Lichstein, Herman C.

    1967-01-01

    Bound biotin-saturated cells were incubated in the presence of biotin and glucose (37 C, pH 7.5) with or without oleic acid, Tween 20, 40, 60, and 80, Aerosol OT, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide, Triton X-100, Non-Ion-Ox, and Haemo-Sol. With low concentrations (up to 5 μg/ml) and short reaction times (up to 10 min), oleic acid stimulated free biotin accumulation. Increased concentrations (10 to 50 μg/ml) or reaction times (10 to 30 min) caused progressive reductions in uptake or increased release of previously accumulated vitamin. Combination of Tween 40 (1 mg/ml) with oleic acid (up to 50 μg/ml) detoxified oleic acid and stimulated free biotin uptake. Oleic acid (5 μg/ml or more) reduced cell viability, an effect which was overcome by Tween 40. All other surfactants tested stimulated free biotin accumulation at sublethal concentrations. Aerosol OT and SDS exhibited the same degree of stimulatory activity as detoxified oleic acid; however, at concentrations higher than 200 μm, a rapid decrease in vitamin accumulation was observed which paralleled that caused by increased oleic acid concentrations. The results suggest that oleic acid and other surfactants affect the permeability of cells of Lactobacillus plantarum (formerly called L. arabinosus) in a similar manner. PMID:6020402

  16. Delivery Systems for In Vivo Use of Nucleic Acid Drugs

    PubMed Central

    Resende, R.R; Torres, H.A.M; Yuahasi, K.K; Majumder, P; Ulrich, H

    2007-01-01

    The notorious biotechnological advance of the last few decades has allowed the development of experimental methods for understanding molecular mechanisms of genes and new therapeutic approaches. Gene therapy is maturing into a viable, practical method with the potential to cure a variety of human illnesses. Some nucleic-acid-based drugs are now available for controlling the progression of genetic diseases by inhibiting gene expression or the activity of their gene products. New therapeutic strategies employ a wide range of molecular tools such as bacterial plasmids containing transgenic inserts, RNA interference and aptamers. A nucleic-acid based constitution confers a lower immunogenic potential and as result of the high stringency selection of large molecular variety, these drugs have high affinity and selectivity for their targets. However, nucleic acids have poor biostability thus requiring chemical modifications and delivery systems to maintain their activity and ease their cellular internalization. This review discusses some of the mechanisms of action and the application of therapies based on nucleic acids such as aptamers and RNA interference as well as platforms for cellular uptake and intracellular delivery of therapeutic oligonucleotides and their trade-offs. PMID:21901073

  17. Expression of amino acid transport systems in cultured human umbilical vein endothelial cells.

    PubMed

    Mann, G E; Pearson, J D; Sheriff, C J; Toothill, V J

    1989-03-01

    1. Nutrient transport in cultured human umbilical vein endothelial cells was characterized using a rapid dual-isotope dilution technique. Microcarrier beads with confluent endothelial cells were perfused in small columns, and uptake and efflux were assessed relative to D-mannitol (extracellular tracer) during a single transit through the column. 2. At tracer concentrations significant unidirectional uptakes were measured for L-leucine (53 +/- 2%), L-phenylalanine (73 +/- 2%), L-serine (40 +/- 4%), L-arginine (42 +/- 3%) and L-ornithine (26 +/- 3%). Uptake for L-proline, D-glucose, dopamine and serotonin was lower (6-10%), whereas uptake for the system A analogue 2-methylaminoisobutyric acid (2-MeAIB) was negligible. Uptakes rapidly decreased with time due to tracer efflux. 3. Endothelial cell transport of L-leucine was markedly inhibited during perfusion with 1 mM-BCH (beta-2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid, system L analogue), L-leucine, D-leucine, L-phenylalanine, L-methionine and L-DOPA. 2-MeAIB, L-cysteine, glycine, L-proline, hydroxy-L-proline, L-aspartate and beta-alanine were poor inhibitors, while L-serine and the cationic substrates L-lysine and L-arginine inhibited uptake by 10-35%. 4. When the kinetics of L-leucine transport were examined over a wide range of substrate concentrations (0.025-1 mM) transport was saturable. A single entry site analysis gave a half-maximal saturation constant Kt = 0.24 +/- 0.08 mM (mean +/- S.E.M., n = 5) and a Vmax = 27.8 +/- 4.6 nmol/min per column (approximately 3 x 10(6) cells). 5. Removal of sodium from the perfusate inhibited tracer uptake of L-leucine, L-serine and L-arginine by respectively 20 +/- 5% (n = 3), 77 +/- 5% (n = 3) and 35 +/- 4% (n = 3). 6. Our results provide the first evidence that cultured human endothelial cells of venous origin express a saturable transport system for large neutral amino acids resembling system L described in brain microvascular endothelium. Detection of Na

  18. Impaired uptake of conjugated bile acids and hepatitis b virus pres1-binding in na+-taurocholate cotransporting polypeptide knockout mice

    PubMed Central

    Slijepcevic, Davor; Kaufman, Christina; Wichers, Catharina GK; Gilglioni, Eduardo H; Lempp, Florian A; Duijst, Suzanne; de Waart, Dirk R; Oude Elferink, Ronald PJ; Mier, Walter; Stieger, Bruno; Beuers, Ulrich; Urban, Stephan; van de Graaf, Stan FJ

    2015-01-01

    The Na+-taurocholate cotransporting polypeptide (NTCP) mediates uptake of conjugated bile acids (BAs) and is localized at the basolateral membrane of hepatocytes. It has recently been recognized as the receptor mediating hepatocyte-specific entry of hepatitis B virus and hepatitis delta virus. Myrcludex B, a peptide inhibitor of hepatitis B virus entry, is assumed to specifically target NTCP. Here, we investigated BA transport and Myrcludex B binding in the first Slc10a1-knockout mouse model (Slc10a1 encodes NTCP). Primary Slc10a1−/− hepatocytes showed absence of sodium-dependent taurocholic acid uptake, whereas sodium-independent taurocholic acid uptake was unchanged. In vivo, this was manifested as a decreased serum BA clearance in all knockout mice. In a subset of mice, NTCP deficiency resulted in markedly elevated total serum BA concentrations, mainly composed of conjugated BAs. The hypercholanemic phenotype was rapidly triggered by a diet supplemented with ursodeoxycholic acid. Biliary BA output remained intact, while fecal BA excretion was reduced in hypercholanemic Slc10a1−/− mice, explained by increased Asbt and Ostα/β expression. These mice further showed reduced Asbt expression in the kidney and increased renal BA excretion. Hepatic uptake of conjugated BAs was potentially affected by down-regulation of OATP1A1 and up-regulation of OATP1A4. Furthermore, sodium-dependent taurocholic acid uptake was inhibited by Myrcludex B in wild-type hepatocytes, while Slc10a1−/− hepatocytes were insensitive to Myrcludex B. Finally, positron emission tomography showed a complete abrogation of hepatic binding of labeled Myrcludex B in Slc10a1-/- mice. Conclusion: The Slc10a1-knockout mouse model supports the central role of NTCP in hepatic uptake of conjugated BAs and hepatitis B virus preS1/Myrcludex B binding in vivo; the NTCP-independent hepatic BA uptake machinery maintains a (slower) enterohepatic circulation of BAs, although it is occasionally

  19. A system to obtain radiotracer uptake data simultaneously with NMR spectra in a high field magnet

    SciTech Connect

    Buchanan, M.; Marsden, P.K.; Garlick, P.B.; Mielke, C.H.

    1996-06-01

    Radiotracer techniques and nuclear magnetic resonance (NMR) spectroscopy are two complementary methods that are widely used to investigate cardiac metabolism. The authors have now developed a novel gamma photon detector system that will operate within a wide-bore, 9.4 T magnet. With this detector in position, it is possible to acquire radiotracer uptake data while simultaneously collecting NMR spectra. The advantages of this new system are firstly, that it enables correlations between radiotracer and NMR data to be made on individual rat hearts, and secondly that it allows the number of experiments required to obtain results of statistical significance to be greatly decreased. The extension of the system, to one in which positron emission tomography (PET) and magnetic resonance imaging (MRI) data are acquired simultaneously, clearly has enormous clinical potential. The detector consists of a NaI(Tl) scintillation crystal coupled to a magnetic field-insensitive photomultiplier tube by a 72.5 cm long, acrylic light pipe. This detector configuration satisfies the two, conflicting requirements of the crystal being near the sample, and thus in a high magnetic field, and the PMT being in a low magnetic field and thus far from the sample. In this paper the authors present the technical specifications of their new system together with what they believe are the first examples of simultaneously acquired NMR spectra and {sup 18}F-fluorodeoxyglucose ({sup 18}FDG) uptake data, obtained from isolated, perfused rat hearts.

  20. 21 CFR 862.1450 - Lactic acid test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Lactic acid test system. 862.1450 Section 862.1450....1450 Lactic acid test system. (a) Identification. A lactic acid test system is a device intended to measure lactic acid in whole blood and plasma. Lactic acid measurements that evaluate the acid-base...

  1. 21 CFR 862.1450 - Lactic acid test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ....1450 Lactic acid test system. (a) Identification. A lactic acid test system is a device intended to measure lactic acid in whole blood and plasma. Lactic acid measurements that evaluate the acid-base status... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Lactic acid test system. 862.1450 Section...

  2. 21 CFR 862.1450 - Lactic acid test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Lactic acid test system. 862.1450 Section 862.1450....1450 Lactic acid test system. (a) Identification. A lactic acid test system is a device intended to measure lactic acid in whole blood and plasma. Lactic acid measurements that evaluate the acid-base...

  3. Uptake of perfluorooctanoic acid, perfluorooctane sulfonate and perfluorooctane sulfonamide by carrot and lettuce from compost amended soil.

    PubMed

    Bizkarguenaga, E; Zabaleta, I; Mijangos, L; Iparraguirre, A; Fernández, L A; Prieto, A; Zuloaga, O

    2016-11-15

    Sewage sludge, which acts like a sink for many pollutants, including metals, pathogens and organic pollutants, that are not completely removed in waste water treatment plants (WWTPs), is applied as a nutrient rich organic fertilizer in many agricultural applications. In the present work, carrot and lettuce crops were grown in two different compost amended soils fortified with perfluorooctanoic acid (PFOA), perfluorosulfonate acid (PFOS) and perfluorosulfonamide (FOSA) and cultivated in a greenhouse. The plants were harvested and divided into root core, root peel and leaves in the case of carrots and into heart and leaves for lettuces. Concentrations for all the different compartments were determined to assess the bioconcentration factors (BCFs) and the plant distribution of the target analytes. The highest carrot BCFs for PFOA and PFOS were determined in the leaves (0.6-3.4), while lower values were calculated in the core (0.05-0.6) and the peel (0.05-1.9) compartments. However, PFOA was taken up in the translocation stream and accumulated more than PFOS in the edible part of lettuce. FOSA was totally degraded in the presence of carrot; however, a lower FOSA degradation was observed in presence of the lettuce, which was dependent on the total organic carbon (TOC) content of the soil. The higher the TOC value, the higher the FOSA degradation observed. No degradation was observed in the crop absence. In the case of the carrot experiments, different polymeric materials (polyethersulfone, PES, polyoxymethylene, and silicone rod) were tested to predict the concentration in the cultivation media. A high correlation (r(2)>0.63) was observed for the BCFs in the PES and in the carrot core and peel for PFOA and PFOS. It could be, concluded that the PES can be used as a first approach for the determination of the uptake of compounds such as PFOS and PFOA in carrot. PMID:27450950

  4. Root-Uptake of C-14 Acetic Acid by Various Plants and C-14 Dynamics Surrounding the Experimental Tessera

    SciTech Connect

    Ogiyama, S.; Takeda, H.; Uchida, S.; Suzuki, H.; Inubushi, K.

    2008-07-01

    Carbon-14 (C-14, t{sub 1/2} = 5.73x10{sup 3} yrs) from radioactive waste is one of the most important radioactive nuclides for environmental assessment in the context of geological disposal, and understanding the transfer of radioactive elements to plants is essential for public health safety. In order to obtain fundamental knowledge, culture experiments using marigold (Tagetes patula L.), tall fescue (Festuca arundinacea S.), paddy rice (Oryza sativa L.), radish (Raphanus sativus L.), and carrot (Daucus carota L.) plants were conducted to examine root-uptake and dynamics of C-14 in the laboratory. The C-14 radioactivity in each plant part (e.g. shoot, root, edible part, etc.), medium (e.g. culture solution, sand, etc.), and air was determined. The distribution of C-14 in the plants was visualized using autoradiography. For a comparison, autoradiography was also done using Na-22. Results of the present study indicated that C-14 labeled CO{sub 2} gas was released from the culture solution to the atmosphere. Clear autoradiography images were observed in plants for the shoots and lower roots which were soaked in the culture solution. The upper roots which were not soaked in the culture solution were not clearly imaged. In the radiotracer experiment using Na-22, a clear image was observed for the whole carrot seedling, even including the upper root, on the autoradiography. However, the amounts of C-14 acetic acid absorbed by all the plants through their roots were considered to be very small. Inorganic carbon transformed from C-14 acetic acid would be taken up by plants through the roots, and some fraction of C-14 would be assimilated into the shoots by photosynthesis. (authors)

  5. Uptake and bioavailability of anthocyanins and phenolic acids from grape/blueberry juice and smoothie in vitro and in vivo.

    PubMed

    Kuntz, Sabine; Rudloff, Silvia; Asseburg, Heike; Borsch, Christian; Fröhling, Bettina; Unger, Franziska; Dold, Sebastian; Spengler, Bernhard; Römpp, Andreas; Kunz, Clemens

    2015-04-14

    The goal of eating five servings of fruits and vegetables a day has not yet been achieved. The intake of polyphenols such as anthocyanins (ACN) could be improved by consuming smoothies and juices that are increasingly popular, especially in children; however, bioavailability data concerning food matrix effects are scarce. Thus, we conducted a randomised, cross-over, bioavailability study (n 10) to determine the bioavailability of ACN and their metabolites from an ACN-rich grape/blueberry juice (841 mg ACN/litre) and smoothie (983 mg ACN/litre) in vivo, and the uptake of a corresponding grape/blueberry extract in vitro. After the intake of beverage (0·33 litres), plasma and fractionated urine samples were collected and analysed by ultra-performance liquid chromatography coupled to MS. The most abundant ACN found in plasma and urine were malvidin and peonidin as native ACN and as glucuronidated metabolites as well as 3,4-dihydroxybenzoic acid (3,4-DHB); minor ACN (delphinidin, cyanidin and petunidin) were only detected as native glycosides. Plasma pharmacokinetics and recoveries of urinary metabolites of ACN were not different for juice or smoothie intake; however, the phenolic acid 3,4-DHB was significantly better bioavailable from juice in comparison to smoothie. In vitro data with absorptive intestinal cells indicated that despite their weak chemical stability, ACN and 3,4-DHB could be detected at the basal side in their native forms. Whether smoothies as well as juices should be recommended to increase the intake of potentially health-promoting ACN and other polyphenols requires the consideration of other ingredients such as their relatively high sugar content. PMID:25778541

  6. Effects of exogenous gibberellic acid3 on iron and manganese plaque amounts and iron and manganese uptake in rice.

    PubMed

    Guo, Yue; Zhu, Changhua; Gan, Lijun; Ng, Denny; Xia, Kai

    2015-01-01

    Gibberellins (GA) regulate various components of plant development. Iron and Mn plaque result from oxiding and hydroxiding Fe and Mn, respectively, on the roots of aquatic plant species such as rice (Oryza sativa L.). In this study, we found that exogenous gibberellic acid3 (GA3) spray decreased Fe plaque, but increased Mn plaque, with applications of Kimura B nutrient solution. Similar effects from GA3, leading to reduced Fe plaque and increased Mn plaque, were also found by scanning electron microscopy and energy dispersive X-ray spectrometric microanalysis. Reduced Fe plaque was observed after applying GA3 to the groups containing added Fe2+ (17 and 42 mg•L(-1)) and an increasing trend was detected in Mn plaques of the Mn2+ (34 and 84 mg•L(-1)) added treatments. In contrast, an inhibitor of GA3, uniconazole, reversed the effects of GA3. The uptake of Fe or Mn in rice plants was enhanced after GA3 application and Fe or Mn plaque production. Strong synergetic effects of GA3 application on Fe plaque production were detected. However, no synergetic effects on Mn plaque production were detected. PMID:25710173

  7. Fluorinated Peptide Nucleic Acids with Fluoroacetyl Side Chain Bearing 5-(F/CF3)-Uracil: Synthesis and Cell Uptake Studies.

    PubMed

    Ellipilli, Satheesh; Palvai, Sandeep; Ganesh, Krishna N

    2016-08-01

    Fluorine incorporation into organic molecules imparts favorable physicochemical properties such as lipophilicity, solubility and metabolic stability necessary for drug action. Toward such applications using peptide nucleic acids (PNA), we herein report the chemical synthesis of fluorinated PNA monomers and biophysical studies of derived PNA oligomers containing fluorine in in the acetyl side chain (-CHF-CO-) bearing nucleobase uracil (5-F/5-CF3-U). The crystal structures of fluorinated racemic PNA monomers reveal interesting base pairing of enantiomers and packing arrangements directed by the chiral F substituent. Reverse phase HPLC show higher hydrophobicity of fluorinated PNA oligomers, dependent on the number and site of the fluorine substitution: fluorine on carbon adjacent to the carbonyl group induces higher lipophilicity than fluorine on nucleobase or in the backbone. The PNA oligomers containing fluorinated bases form hybrids with cDNA/RNA with slightly lower stability compared to that of unmodified aeg PNA, perhaps due to electronic effects. The uptake of fluorinated homooligomeric PNAs by HeLa cells was as facile as that of nonfluorinated PNA. In conjunction with our previous work on PNAs fluorinated in backbone and at N-terminus, it is evident that the fluorinated PNAs have potential to emerge as a new class of PNA analogues for applications in functional inhibition of RNA. PMID:27391099

  8. Effects of Exogenous Gibberellic Acid3 on Iron and Manganese Plaque Amounts and Iron and Manganese Uptake in Rice

    PubMed Central

    Guo, Yue; Zhu, Changhua; Gan, Lijun; Ng, Denny; Xia, Kai

    2015-01-01

    Gibberellins (GA) regulate various components of plant development. Iron and Mn plaque result from oxiding and hydroxiding Fe and Mn, respectively, on the roots of aquatic plant species such as rice (Oryza sativa L.). In this study, we found that exogenous gibberellic acid3 (GA3) spray decreased Fe plaque, but increased Mn plaque, with applications of Kimura B nutrient solution. Similar effects from GA3, leading to reduced Fe plaque and increased Mn plaque, were also found by scanning electron microscopy and energy dispersive X-ray spectrometric microanalysis. Reduced Fe plaque was observed after applying GA3 to the groups containing added Fe2+ (17 and 42 mg•L-1) and an increasing trend was detected in Mn plaques of the Mn2+ (34 and 84 mg•L-1) added treatments. In contrast, an inhibitor of GA3, uniconazole, reversed the effects of GA3. The uptake of Fe or Mn in rice plants was enhanced after GA3 application and Fe or Mn plaque production. Strong synergetic effects of GA3 application on Fe plaque production were detected. However, no synergetic effects on Mn plaque production were detected. PMID:25710173

  9. An in situ optical imaging system for measuring lipid uptake, vessel contraction, and lymph flow in small animal lymphatic vessels

    NASA Astrophysics Data System (ADS)

    Kassis, Timothy; Weiler, Michael J.; Dixon, J. Brandon

    2012-03-01

    All dietary lipids are transported to venous circulation through the lymphatic system, yet the underlying mechanisms that regulate this process remain unclear. Understanding how the lymphatics functionally respond to changes in lipid load is important in the diagnosis and treatment of lipid and lymphatic related diseases such as obesity, hypercholesterolemia, and lymphedema. Therefore, we sought to develop an in situ imaging system to quantify and correlate lymphatic function as it relates to lipid transport. A custom-built optical set-up provides us with the capability of dual-channel imaging of both high-speed bright-field video and fluorescence simultaneously. This is achieved by dividing the light path into two optical bands. Utilizing high-speed and back-illuminated CCD cameras and post-acquisition image processing algorithms, we have the potential quantify correlations between vessel contraction, lymph flow and lipid concentration of mesenteric lymphatic vessels in situ. Local flow velocity is measured through lymphocyte tracking, vessel contraction through measurements of the vessel walls and lipid uptake through fluorescence intensity tracking of a fluorescent long chain fatty acid analogue, Bodipy FL C16. This system will prove to be an invaluable tool for both scientists studying lymphatic function in health and disease, and those investigating strategies for targeting the lymphatic system with orally delivered drugs.

  10. l-Methionine Placental Uptake

    PubMed Central

    Araújo, João R.; Correia-Branco, Ana; Ramalho, Carla; Gonçalves, Pedro; Pinho, Maria J.; Keating, Elisa

    2013-01-01

    Our aim was to investigate the influence of gestational diabetes mellitus (GDM) and GDM-associated conditions upon the placental uptake of 14C-l-methionine (14C-l-Met). The 14C-l-Met uptake by human trophoblasts (TBs) obtained from normal pregnancies (normal trophoblast [NTB] cells) is mainly system l-type amino acid transporter 1 (LAT1 [L])-mediated, although a small contribution of system y+LAT2 is also present. Comparison of 14C-l-Met uptake by NTB and by human TBs obtained from GDM pregnancies (diabetic trophoblast [DTB] cells) reveals similar kinetics, but a contribution of systems A, LAT2, and b0+ and a greater contribution of system y+LAT1 appears to exist in DTB cells. Short-term exposure to insulin and long-term exposure to high glucose, tumor necrosis factor-α, and leptin decrease 14C-l-Met uptake in a human TB (Bewo) cell line. The effect of leptin was dependent upon phosphoinositide 3-kinase, extracellular-signal-regulated kinase 1/2 (ERK/MEK 1/2), and p38 mitogen-activated protein kinase. In conclusion, GDM does not quantitatively alter 14C-l-Met placental uptake, although it changes the nature of transporters involved in that process. PMID:23653387

  11. Uptake and Reactions of Formaldehyde, Acetaldehyde, Acetone, Propanal and Ethanol in Sulfuric Acid solutions at 200-240 K: Implications for upper tropospheric aerosol composition

    NASA Astrophysics Data System (ADS)

    Iraci, L. T.; Williams, M. B.; Axson, J.; Michelsen, R.

    2007-12-01

    The production of light absorbing, organic material in aerosol that is normally considered to be transparent in the UV and visible wavelength regions has significant implications for biogeochemical cycling and climate modelling. Production mechanisms likely involve carbonyl compounds such as formaldehyde, acetone, acetaldehyde and propanal that are present in significant quantities in the upper troposphere (UT). In this study, we have performed experiments focusing on a class of acid catalyzed carbonyl reactions, the formation of acetals. R2C=O + 2R'OH --> R2C(OR')2 + H2O Using a Knudsen cell apparatus, we have measured the rate of uptake of formaldehyde, acetaldehyde, acetone, propanal, and ethanol into sulfuric acid solutions ranging between 40-70 wt% of acid, containing 0-0.1 M of ethanol, acetone or formaldehyde at temperatures of 220-250 K. For all reactant pairs, the aldol condensation path, including self reaction, should be insignificant at the acidities studied. Evidence for reaction between organics was observed for all pairs, except those involving propanal which were likely limited by the very low solubility. We attribute enhanced uptake to the formation of acetals, such as 1,1-diethoxyethane and 2,2- diethoxypropane, among others. Enhanced uptake was observed to proceed on timescales > 1 hour and sometimes shows complex dependence on acidity that is likely related to speciation of the individual carbonyls in acidic solution. The acetal products do not absorb in the visible but are less volatile than parent molecules, allowing for accumulation in sulfuric acid particles, and enhanced uptake. Cross reactions of carbonyls with alcohols in sulfuric acid medium have not been previously measured, yet methanol and ethanol show high solubility and are present at significant concentrations in the UT. Thus even at slow reaction rates, the acetal reaction has ample starting material and proceeds under conditions common to the UT. We will present results for the

  12. Rat long chain acyl-CoA synthetase 5 increases fatty acid uptake and partitioning to cellular triacylglycerol in McArdle-RH7777 cells.

    PubMed

    Mashek, Douglas G; McKenzie, Michelle A; Van Horn, Cynthia G; Coleman, Rosalind A

    2006-01-13

    Long chain acyl-CoA synthetase (ACSL) catalyzes the initial step in long chain fatty acid metabolism. Of the five mammalian ACSL isoforms cloned and characterized, ACSL5 is the only isoform found to be located, in part, on mitochondria and thus was hypothesized to be involved in fatty acid oxidation. To elucidate the specific roles of ACSL5 in fatty acid metabolism, we used adenoviral-mediated overexpression of ACSL5 (Ad-ACSL5) in rat hepatoma McArdle-RH7777 cells. Confocal microscopy revealed that Ad-ACSL5 colocalized to both mitochondria and endoplasmic reticulum. When compared with cells infected with Ad-GFP, Ad-ACSL5-infected cells at 24 h after infection had 2-fold higher acyl-CoA synthetase activities and 30% higher rates of fatty acid uptake when incubated with 500 microM [1-(14)C]oleic acid. Metabolism of [1-(14)C]oleic acid to cellular triacylglycerol (TAG) increased 42% in Ad-ACSL5-infected cells, but when compared with control cells, metabolism to acid-soluble metabolites, phospholipids, and medium TAG did not differ substantially. The incorporation of [1-(14)C]oleate and [1,2,3-(3)H]glycerol into TAG was similar in Ad-ACSL5-infected cells, thus indicating that Ad-ACSL5 increased TAG synthesis through both de novo and reacylation pathways. However, [1-(14)C]acetic acid incorporation into cellular lipids showed that, when compared with control cells, Ad-ACSL5-infected cells did not increase the metabolism of fatty acids that were derived from de novo synthesis. These results suggest that uptake of fatty acids into cells is regulated by metabolism and that overexpressed ACSL5 partitions exogenously derived fatty acids toward TAG synthesis and storage. PMID:16263710

  13. Dual-channel in-situ optical imaging system for quantifying lipid uptake and lymphatic pump function.

    PubMed

    Kassis, Timothy; Kohan, Alison B; Weiler, Michael J; Nipper, Matthew E; Cornelius, Rachel; Tso, Patrick; Dixon, J Brandon

    2012-08-01

    Nearly all dietary lipids are transported from the intestine to venous circulation through the lymphatic system, yet the mechanisms that regulate this process remain unclear. Elucidating the mechanisms involved in the functional response of lymphatics to changes in lipid load would provide valuable insight into recent implications of lymphatic dysfunction in lipid related diseases. Therefore, we sought to develop an in situ imaging system to quantify and correlate lymphatic function as it relates to lipid transport. The imaging platform provides the capability of dual-channel imaging of both high-speed bright-field video and fluorescence simultaneously. Utilizing post-acquisition image processing algorithms, we can quantify correlations between vessel pump function, lymph flow, and lipid concentration of mesenteric lymphatic vessels in situ. All image analysis is automated with customized LabVIEW virtual instruments; local flow is measured through lymphocyte velocity tracking, vessel contraction through measurements of the vessel wall displacement, and lipid uptake through fluorescence intensity tracking of an orally administered fluorescently labelled fatty acid analogue, BODIPY FL C16. This system will prove to be an invaluable tool for scientists studying intestinal lymphatic function in health and disease, and those investigating strategies for targeting the lymphatics with orally delivered drugs to avoid first pass metabolism. PMID:23224192

  14. Dual-channel in-situ optical imaging system for quantifying lipid uptake and lymphatic pump function

    NASA Astrophysics Data System (ADS)

    Kassis, Timothy; Kohan, Alison B.; Weiler, Michael J.; Nipper, Matthew E.; Cornelius, Rachel; Tso, Patrick; Brandon Dixon, J.

    2012-08-01

    Nearly all dietary lipids are transported from the intestine to venous circulation through the lymphatic system, yet the mechanisms that regulate this process remain unclear. Elucidating the mechanisms involved in the functional response of lymphatics to changes in lipid load would provide valuable insight into recent implications of lymphatic dysfunction in lipid related diseases. Therefore, we sought to develop an in situ imaging system to quantify and correlate lymphatic function as it relates to lipid transport. The imaging platform provides the capability of dual-channel imaging of both high-speed bright-field video and fluorescence simultaneously. Utilizing post-acquisition image processing algorithms, we can quantify correlations between vessel pump function, lymph flow, and lipid concentration of mesenteric lymphatic vessels in situ. All image analysis is automated with customized LabVIEW virtual instruments; local flow is measured through lymphocyte velocity tracking, vessel contraction through measurements of the vessel wall displacement, and lipid uptake through fluorescence intensity tracking of an orally administered fluorescently labelled fatty acid analogue, BODIPY FL C16. This system will prove to be an invaluable tool for scientists studying intestinal lymphatic function in health and disease, and those investigating strategies for targeting the lymphatics with orally delivered drugs to avoid first pass metabolism.

  15. Dual-channel in-situ optical imaging system for quantifying lipid uptake and lymphatic pump function

    PubMed Central

    Kassis, Timothy; Kohan, Alison B.; Weiler, Michael J.; Nipper, Matthew E.; Cornelius, Rachel; Tso, Patrick

    2012-01-01

    Abstract. Nearly all dietary lipids are transported from the intestine to venous circulation through the lymphatic system, yet the mechanisms that regulate this process remain unclear. Elucidating the mechanisms involved in the functional response of lymphatics to changes in lipid load would provide valuable insight into recent implications of lymphatic dysfunction in lipid related diseases. Therefore, we sought to develop an in situ imaging system to quantify and correlate lymphatic function as it relates to lipid transport. The imaging platform provides the capability of dual-channel imaging of both high-speed bright-field video and fluorescence simultaneously. Utilizing post-acquisition image processing algorithms, we can quantify correlations between vessel pump function, lymph flow, and lipid concentration of mesenteric lymphatic vessels in situ. All image analysis is automated with customized LabVIEW virtual instruments; local flow is measured through lymphocyte velocity tracking, vessel contraction through measurements of the vessel wall displacement, and lipid uptake through fluorescence intensity tracking of an orally administered fluorescently labelled fatty acid analogue, BODIPY FL C16. This system will prove to be an invaluable tool for scientists studying intestinal lymphatic function in health and disease, and those investigating strategies for targeting the lymphatics with orally delivered drugs to avoid first pass metabolism. PMID:23224192

  16. The comparison of 2-18F-2-deoxyglucose and 15-(ortho-123I-phenyl)-pentadecanoic acid uptake in persisting defects on thallium-201 tomography in myocardial infarction

    SciTech Connect

    Henrich, M.M.; Vester, E.; von der Lohe, E.; Herzog, H.; Simon, H.; Kuikka, J.T.; Feinendegen, L.E. )

    1991-07-01

    The myocardial uptake of glucose and fatty acids into 201Tl redistribution defects were studied in 32 patients with myocardial infarction by tomography using 2-18F-2-deoxyglucose (FDG) and 15-(ortho-123I-phenyl)-pentadecanoic acid (oPPA). A total of 1153 segments were analyzed, 408 (35%) of which showed a persistent thallium-defect in stress-redistribution images. Of the segments with a decreased 201Tl uptake in these redistribution tomograms, 50.5% had a decreased uptake of both FDG and oPPA; in 21.8% FDG as well as oPPA uptake was within normal range. Normal FDG uptake but decreased oPPA uptake was detected in 17.4%, whereas 10.3% of the segments had normal oPPA uptake but decreased FDG uptake (chi-square test, p less than 0.001). A significant correlation of FDG and oPPA uptake (r = 0.51) was found in the segments with persistent 201Tl defect. Thus, a substantial fraction of persistent thallium-defects after healed myocardial infarction exhibit FDG as well as oPPA uptake, probably due to residual fatty acid metabolism in partially ischemic regions.

  17. Angiopoietin-Like 4 Mediates PPAR Delta Effect on Lipoprotein Lipase-Dependent Fatty Acid Uptake but Not on Beta-Oxidation in Myotubes

    PubMed Central

    Robciuc, Marius R.; Skrobuk, Paulina; Anisimov, Andrey; Olkkonen, Vesa M.; Alitalo, Kari; Eckel, Robert H.; Koistinen, Heikki A.; Jauhiainen, Matti; Ehnholm, Christian

    2012-01-01

    Peroxisome proliferator-activated receptor (PPAR) delta is an important regulator of fatty acid (FA) metabolism. Angiopoietin-like 4 (Angptl4), a multifunctional protein, is one of the major targets of PPAR delta in skeletal muscle cells. Here we investigated the regulation of Angptl4 and its role in mediating PPAR delta functions using human, rat and mouse myotubes. Expression of Angptl4 was upregulated during myotubes differentiation and by oleic acid, insulin and PPAR delta agonist GW501516. Treatment with GW501516 or Angptl4 overexpression inhibited both lipoprotein lipase (LPL) activity and LPL-dependent uptake of FAs whereas uptake of BSA-bound FAs was not affected by either treatment. Activation of retinoic X receptor (RXR), PPAR delta functional partner, using bexarotene upregulated Angptl4 expression and inhibited LPL activity in a PPAR delta dependent fashion. Silencing of Angptl4 blocked the effect of GW501516 and bexarotene on LPL activity. Treatment with GW501516 but not Angptl4 overexpression significantly increased palmitate oxidation. Furthermore, Angptl4 overexpression did not affect the capacity of GW501516 to increase palmitate oxidation. Basal and insulin stimulated glucose uptake, glycogen synthesis and glucose oxidation were not significantly modulated by Angptl4 overexpression. Our findings suggest that FAs-PPARdelta/RXR-Angptl4 axis controls the LPL-dependent uptake of FAs in myotubes, whereas the effect of PPAR delta activation on beta-oxidation is independent of Angptl4. PMID:23056264

  18. Spatiotemporal variation of nitrate uptake kinetics within the maize (Zea mays L.) root system is associated with greater nitrate uptake and interactions with architectural phenes.

    PubMed

    York, Larry M; Silberbush, Moshe; Lynch, Jonathan P

    2016-06-01

    Increasing maize nitrogen acquisition efficiency is a major goal for the 21st century. Nitrate uptake kinetics (NUK) are defined by I max and K m, which denote the maximum uptake rate and the affinity of transporters, respectively. Because NUK have been studied predominantly at the molecular and whole-root system levels, little is known about the functional importance of NUK variation within root systems. A novel method was created to measure NUK of root segments that demonstrated variation in NUK among root classes (seminal, lateral, crown, and brace). I max varied among root class, plant age, and nitrate deprivation combinations, but was most affected by plant age, which increased I max, and nitrate deprivation time, which decreased I max K m was greatest for crown roots. The functional-structural simulation SimRoot was used for sensitivity analysis of plant growth to root segment I max and K m, as well as to test interactions of I max with root system architectural phenes. Simulated plant growth was more sensitive to I max than K m, and reached an asymptote near the maximum I max observed in the empirical studies. Increasing the I max of lateral roots had the largest effect on shoot growth. Additive effects of I max and architectural phenes on nitrate uptake were observed. Empirically, only lateral root tips aged 20 d operated at the maximum I max, and simulations demonstrated that increasing all seminal and lateral classes to this maximum rate could increase plant growth by as much as 26%. Therefore, optimizing I max for all maize root classes merits attention as a promising breeding goal. PMID:27037741

  19. Biomass production and nutrient uptake by Neochloris oleoabundans in an open trough system.

    PubMed

    Murray, Kyle E; Healy, Frank G; McCord, Rebecca S; Shields, Jeremy A

    2011-04-01

    The purpose of this paper is to present biomass and nutrient uptake data from Neochloris oleoabundans production in an open trough system. The growth medium used was BG11, temperature ranged from 16.7 °C to 25.3 °C, and pH ranged from 5.52 to 9.94 because the customary pH increase during algal biomass production was moderated by incoming CO(2) gas streams (atmospheric, 2%, 4%, and 6% CO(2)). Peak concentrations of algal biomass ranged from 643 to 970 mg L(-1), specific growth rates ranged from 0.15 to 0.37 day(-1), and doubling times ranged from 4.8 to 1.9 days. Carbon, nitrogen, and phosphorus were incorporated into the biomass at 0.05%, 8.3%, and 54% of supplied amounts. Open growth systems supplemented with CO(2) should be designed to regulate medium pH within the range of 6.3 to 7.1. Future research should examine various media and alternative carbon sources to decrease doubling times, increase peak concentrations, and optimize nutrient uptake. PMID:21184060

  20. The effect of external stimuli on the uranyl ions uptake capacity of poly( N-vinyl 2-pyrrolidone/itaconic acid) hydrogels prepared by gamma rays

    NASA Astrophysics Data System (ADS)

    Kantoğlu, Ö.; Şen, M.; Güven, O.

    1999-05-01

    The effect of external stimuli such as pH of the solution, ionic strength and temperature on the uranyl ions uptake capacity of poly( N-vinyl 2-pyrrolidone/itaconic acid) (P(VP/IA)) hydrogels was investigated. Polyelectrolyte P(VP/IA) hydrogels with varying compositions were prepared in the form of rods from ternary mixtures of N-vinyl 2-pyrrolidone/itaconic acid/water. Uranyl adsorption capacity of hydrogels were found to increase from 26.7 to 70 (mg UO 22+ /g dry gel) with decreasing pH of the swelling solution. Adsorption studies have shown that other stimuli, such as temperature and ionic strength of the swelling solution have also influence on the uranyl ions uptake capacity of P(VP/IA) hydrogels.

  1. Micro-electro-mechanical systems phosphoric acid fuel cell

    DOEpatents

    Sopchak, David A.; Morse, Jeffrey D.; Upadhye, Ravindra S.; Kotovsky, Jack; Graff, Robert T.

    2010-08-17

    A phosphoric acid fuel cell system comprising a porous electrolyte support, a phosphoric acid electrolyte in the porous electrolyte support, a cathode electrode contacting the phosphoric acid electrolyte, and an anode electrode contacting the phosphoric acid electrolyte.

  2. Micro-electro-mechanical systems phosphoric acid fuel cell

    DOEpatents

    Sopchak, David A.; Morse, Jeffrey D.; Upadhye, Ravindra S.; Kotovsky, Jack; Graff, Robert T.

    2010-12-21

    A phosphoric acid fuel cell system comprising a porous electrolyte support, a phosphoric acid electrolyte in the porous electrolyte support, a cathode electrode contacting the phosphoric acid electrolyte, and an anode electrode contacting the phosphoric acid electrolyte.

  3. Sulfuric acid thermoelectrochemical system and method

    DOEpatents

    Ludwig, Frank A.

    1989-01-01

    A thermoelectrochemical system in which an electrical current is generated between a cathode immersed in a concentrated sulfuric acid solution and an anode immersed in an aqueous buffer solution of sodium bisulfate and sodium sulfate. Reactants consumed at the electrodes during the electrochemical reaction are thermochemically regenerated and recycled to the electrodes to provide continuous operation of the system.

  4. Functional Dependence between Septal Protein SepJ from Anabaena sp. Strain PCC 7120 and an Amino Acid ABC-Type Uptake Transporter

    PubMed Central

    Escudero, Leticia; Mariscal, Vicente

    2015-01-01

    ABSTRACT In the diazotrophic filaments of heterocyst-forming cyanobacteria, two different cell types, the CO2-fixing vegetative cells and the N2-fixing heterocysts, exchange nutrients, including some amino acids. In the model organism Anabaena sp. strain PCC 7120, the SepJ protein, composed of periplasmic and integral membrane (permease) sections, is located at the intercellular septa joining adjacent cells in the filament. The unicellular cyanobacterium Synechococcus elongatus strain PCC 7942 bears a gene, Synpcc7942_1024 (here designated dmeA), encoding a permease homologous to the SepJ permease domain. Synechococcus strains lacking dmeA or lacking dmeA and expressing Anabaena sepJ were constructed. The Synechococcus dmeA mutant showed a significant 22 to 32% decrease in the uptake of aspartate, glutamate, and glutamine, a phenotype that could be partially complemented by Anabaena sepJ. Synechococcus mutants of an ATP-binding-cassette (ABC)-type transporter for polar amino acids showed >98% decreased uptake of glutamate irrespective of the presence of dmeA or Anabaena sepJ in the same strain. Thus, Synechococcus DmeA or Anabaena SepJ is needed to observe full (or close to full) activity of the ABC transporter. An Anabaena sepJ deletion mutant was significantly impaired in glutamate and aspartate uptake, which also in this cyanobacterium requires the activity of an ABC-type transporter for polar amino acids. SepJ appears therefore to generally stimulate the activity of cyanobacterial ABC-type transporters for polar amino acids. Conversely, an Anabaena mutant of three ABC-type transporters for amino acids was impaired in the intercellular transfer of 5-carboxyfluorescein, a SepJ-related property. Our results unravel possible functional interactions in transport elements important for diazotrophic growth. IMPORTANCE Membrane transporters are essential for many aspects of cellular life, from uptake and export of substances in unicellular organisms to intercellular

  5. Testing a structural model of young driver willingness to uptake Smartphone Driver Support Systems.

    PubMed

    Kervick, Aoife A; Hogan, Michael J; O'Hora, Denis; Sarma, Kiran M

    2015-10-01

    There is growing interest in the potential value of using phone applications that can monitor driver behaviour (Smartphone Driver Support Systems, 'SDSSs') in mitigating risky driving by young people. However, their value in this regard will only be realised if young people are willing to use this technology. This paper reports the findings of a study in which a novel structural model of willingness to use SDSSs was tested. Grounded in the driver monitoring and Technology Acceptance (TA) research literature, the model incorporates the perceived risks and gains associated with potential SDSS usage and additional social cognitive factors, including perceived usability and social influences. A total of 333 smartphone users, aged 18-24, with full Irish driving licenses completed an online questionnaire examining willingness or Behavioural Intention (BI) to uptake a SDSS. Following exploratory and confirmatory factor analyses, structural equation modelling indicated that perceived gains and social influence factors had significant direct effects on BI. Perceived risks and social influence also had significant indirect effects on BI, as mediated by perceived gains. Overall, this model accounted for 72.5% of the variance in willingness to uptake SDSSs. Multi-group structural models highlighted invariance of effects across gender, high and low risk drivers, and those likely or unlikely to adopt novel phone app technologies. These findings have implications for our understanding of the willingness of young drivers to adopt and use SDSSs, and highlight potential factors that could be targeted in behavioural change interventions seeking to improve usage rates. PMID:26277411

  6. Coupling Physiology and Gene Regulation in Bacteria: The Phosphotransferase Sugar Uptake System Delivers the Signals

    NASA Astrophysics Data System (ADS)

    Stülke, Jörg; Hillen, Wolfgang

    In many bacteria a crucial link between metabolism and regulation of catabolic genes is based on the phosphotransferase sugar uptake system (PTS). We summarize the mechanisms of the signaling pathways originating from PTS and leading to regulation of transcription. A protein domain, called PTS regulation domain (PRD), is linked to many antiterminators and transcriptional activators and regulates their activity depending on its state of phosphorylation. Two sites can be phosphorylated in most PRDs: HPr-dependent modification at one site leads to activation while enzyme II dependent phosphorylation of the other site renders it inactive. In addition, PTS components are used to generate cofactors for regulators of transcription. The paradigm is the enzyme II dependent activity of adenylate cyclase determining the cyclic AMP level in Escherichia coli and thereby the activity of the catabolite activator protein. In many gram-positive bacteria catabolite repression is mediated by the catabolite control protein CcpA, which requires HPr Ser-46 phosphate as a cofactor to regulate transcription of catabolic genes. HPr Ser-46 phosphate is produced by HPr kinase, the activity of which is under metabolic control via the concentrations of glycolytic intermediates. These recent results establish a multifaceted regulatory role for PTS in addition to its well-established function in active sugar uptake.

  7. Overlap of copper and iron uptake systems in mitochondria in Saccharomyces cerevisiae

    PubMed Central

    Wang, Jing; Gammon, Micah G.; Maynard, Margaret K.; White, Olivia L.; Cobine, Jai A.; Mahone, Wilkerson K.

    2016-01-01

    In Saccharomyces cerevisiae, the mitochondrial carrier family protein Pic2 imports copper into the matrix. Deletion of PIC2 causes defects in mitochondrial copper uptake and copper-dependent growth phenotypes owing to decreased cytochrome c oxidase activity. However, copper import is not completely eliminated in this mutant, so alternative transport systems must exist. Deletion of MRS3, a component of the iron import machinery, also causes a copper-dependent growth defect on non-fermentable carbon. Deletion of both PIC2 and MRS3 led to a more severe respiratory growth defect than either individual mutant. In addition, MRS3 expressed from a high copy number vector was able to suppress the oxygen consumption and copper uptake defects of a strain lacking PIC2. When expressed in Lactococcus lactis, Mrs3 mediated copper and iron import. Finally, a PIC2 and MRS3 double mutant prevented the copper-dependent activation of a heterologously expressed copper sensor in the mitochondrial intermembrane space. Taken together, these data support a role for the iron transporter Mrs3 in copper import into the mitochondrial matrix. PMID:26763345

  8. Role of the twin-arginine translocase (tat) system in iron uptake in Listeria monocytogenes.

    PubMed

    Tiwari, Kiran B; Birlingmair, Jacob; Wilkinson, Brian J; Jayaswal, Radheshyam K

    2015-02-01

    The twin-arginine translocase (Tat) complex is a unique system that translocates folded proteins across the cytoplasmic membrane. In this study, the Tat transporter system in Listeria monocytogenes was characterized to determine the role of Tat in the iron uptake pathway. A putative tatAC operon, containing conserved Fur-binding sequences in the promoter region, has been predicted to encode Tat-translocase components. Another operon, fepCAB, with a putative Fur-binding sequence in the promoter, close to TatAC, was identified in the complementary strands of L. monocytogenes. Electrophoretic mobility shift assay showed that the listerial Fur-repressor binds to the promoter of the tatAC operon, suggesting that tat is under Fur regulation. Using a heterologous system in a reporter assay, FepB was translocated across the membrane. Mutations in tatC and fepB were constructed to determine the roles of Tat and FepB, respectively. In a whole-cell ferric reductase assay, the fepB and tatC mutants were found to have reduced levels of ferric reductase activities compared with those of the isogenic parent strain. Although ferric reductase activity has been demonstrated in Listeria, a conventional ferric reductase encoding sequence does not appear to be present in its genome. Hence, we propose that fepB encodes a ferric reductase enzyme, which is translocated by the Tat-translocase system onto the bacterial cell surface, and plays an important role in the reductive iron uptake process in L. monocytogenes. PMID:25416690

  9. 21 CFR 862.1290 - Fatty acids test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Fatty acids test system. 862.1290 Section 862.1290....1290 Fatty acids test system. (a) Identification. A fatty acids test system is a device intended to measure fatty acids in plasma and serum. Measurements of fatty acids are used in the diagnosis...

  10. Effects of cAMP modulators on long-chain fatty-acid uptake and utilization by electrically stimulated rat cardiac myocytes.

    PubMed Central

    Luiken, J J F P; Willems, J; Coort, S L M; Coumans, W A; Bonen, A; Van Der Vusse, G J; Glatz, J F C

    2002-01-01

    Recently, we established that cellular contractions increase long-chain fatty-acid (FA) uptake by cardiac myocytes. This increase is dependent on the transport function of an 88 kDa membrane FA transporter, FA translocase (FAT/CD36), and, in analogy to skeletal muscle, is likely to involve its translocation from an intracellular pool to the sarcolemma. In the present study, we investigated whether cAMP-dependent signalling is involved in this translocation process. Isoproterenol, dibutyryl-cAMP and the phosphodiesterase (PDE) inhibitor, amrinone, which markedly raised the intracellular cAMP level, did not affect cellular FA uptake, but influenced the fate of intracellular FAs by directing these to mitochondrial oxidation in electrostimulated cardiac myocytes. The PDE inhibitors 3-isobutyl-1-methylxanthine, milrinone and dipyridamole each significantly stimulated FA uptake as well as intracellular cAMP levels, but these effects were quantitatively unrelated. The stimulatory effects of these PDE inhibitors were antagonized by sulpho- N -succinimidylpalmitate, indicating the involvement of FAT/CD36, albeit that the different PDE inhibitors use different molecular mechanisms to stimulate FAT/CD36-mediated FA uptake. Notably, 3-isobutyl-1-methylxanthine and milrinone increased the intrinsic activity of FAT/CD36, possibly through its covalent modification, and dipyridamole induces translocation of FAT/CD36 to the sarcolemma. Elevation of intracellular cGMP, but not of cAMP, by the PDE inhibitor zaprinast did not have any effect on FA uptake and metabolism by cardiac myocytes. The stimulatory effects of PDE inhibitors on cardiac FA uptake should be considered when applying these agents in clinical medicine. PMID:12093365

  11. Exogenous abscisic acid application decreases cadmium accumulation in Arabidopsis plants, which is associated with the inhibition of IRT1-mediated cadmium uptake

    PubMed Central

    Fan, Shi Kai; Fang, Xian Zhi; Guan, Mei Yan; Ye, Yi Quan; Lin, Xian Yong; Du, Shao Ting; Jin, Chong Wei

    2014-01-01

    Cadmium (Cd) contamination of agricultural soils is an increasingly serious problem. Measures need to be developed to minimize Cd entering the human food chain from contaminated soils. We report here that, under Cd exposure condition, application with low doses of (0.1–0.5 μM) abscisic acid (ABA) clearly inhibited Cd uptake by roots and decreased Cd level in Arabidopsis wild-type plants (Col-0). Expression of IRT1 in roots was also strongly inhibited by ABA treatment. Decrease in Cd uptake and the inhibition of IRT1 expression were clearly lesser pronounced in an ABA-insensitive double mutant snrk2.2/2.3 than in the Col-0 in response to ABA application. The ABA-decreased Cd uptake was found to correlate with the ABA-inhibited IRT1 expression in the roots of Col-0 plants fed two different levels of iron. Furthermore, the Cd uptake of irt1 mutants was barely affected by ABA application. These results indicated that inhibition of IRT1 expression is involved in the decrease of Cd uptake in response to exogenous ABA application. Interestingly, ABA application increased the iron level in both Col-0 plants and irt1 mutants, suggesting that ABA-increased Fe acquisition does not depend on the IRT1 function, but on the contrary, the ABA-mediated inhibition of IRT1 expression may be due to the elevation of iron level in plants. From our results, we concluded that ABA application might increase iron acquisition, followed by the decrease in Cd uptake by inhibition of IRT1 activity. Thus, for crop production in Cd contaminated soils, developing techniques based on ABA application potentially is a promising approach for reducing Cd accumulation in edible organs in plants. PMID:25566293

  12. Differing patterns of striatal sup 18 F-dopa uptake in Parkinson's disease, multiple system atrophy, and progressive supranuclear palsy

    SciTech Connect

    Brooks, D.J.; Ibanez, V.; Sawle, G.V.; Quinn, N.; Lees, A.J.; Mathias, C.J.; Bannister, R.; Marsden, C.D.; Frackowiak, R.S. )

    1990-10-01

    Using positron emission tomography (PET), we studied regional striatal 18F-dopa uptake in 16 patients with L-dopa-responsive Parkinson's disease (PD), 18 patients with multiple system atrophy, and 10 patients with progressive supranuclear palsy. Results were compared with those of 30 age-matched normal volunteers. The patients with PD showed significantly reduced mean uptake of 18F-dopa in the caudate and putamen compared to controls, but while function in the posterior part of the putamen was severely impaired (45% of normal), function in the anterior part of the putamen and in the caudate was relatively spared (62% and 84% of normal). Mean 18F-dopa uptake in the posterior putamen was depressed to similar levels in all patients. Unlike patients with PD, the patients with progressive supranuclear palsy showed equally severe impairment of mean 18F-dopa uptake in the anterior and posterior putamen. Caudate 18F-dopa uptake was also significantly lower in patients with progressive supranuclear palsy than in patients with PD, being depressed to the same level as that in the putamen. Mean 18F-dopa uptake values in the anterior putamen and caudate in patients with multiple system atrophy lay between PD and progressive supranuclear palsy levels. Locomotor disability of individual patients with PD or multiple system atrophy correlated with decline in striatal 18F-dopa uptake, but this was not the case for the patients with progressive supranuclear palsy. We conclude that patients with PD have selective nigral pathological features with relative preservation of the dopaminergic function in the anterior putamen and caudate, whereas there is progressively more extensive nigral involvement in multiple system atrophy and progressive supranuclear palsy.

  13. The role of receptor topology in the vitamin D3 uptake and Ca(2+) response systems.

    PubMed

    Morrill, Gene A; Kostellow, Adele B; Gupta, Raj K

    2016-09-01

    The steroid hormone, vitamin D3, regulates gene transcription via at least two receptors and initiates putative rapid response systems at the plasma membrane. The vitamin D receptor (VDR) binds vitamin D3 and a second receptor, importin-4, imports the VDR-vitamin D3 complex into the nucleus via nuclear pores. Here we present evidence that the Homo sapiens VDR homodimer contains two transmembrane (TM) helices ((327)E - D(342)), two TM "half-helix" ((264)K N(276)), one or more large channels, and 16 cholesterol binding (CRAC/CARC) domains. The importin-4 monomer exhibits 3 pore-lining regions ((226)E - L(251); (768)V - G(783); (876)S - A(891)) and 16 CRAC/CARC domains. The MEMSAT algorithm indicates that VDR and importin-4 may not be restricted to cytoplasm and nucleus. VDR homodimer TM helix-topology predicts insertion into the plasma membrane, with two 84 residue C-terminal regions being extracellular. Similarly, MEMSAT predicts importin-4 insertion into the plasma membrane with 226 residue extracellular N-terminal regions and 96 residue C-terminal extracellular loops; with the pore-lining regions contributing gated Ca(2+) channels. The PoreWalker algorithm indicates that, of the 427 residues in each VDR monomer, 91 line the largest channel, including two vitamin D3 binding sites and residues from both the TM helix and "half-helix". Cholesterol-binding domains also extend into the channel within the ligand binding region. Programmed changes in bound cholesterol may regulate both membrane Ca(2+) response systems and vitamin D3 uptake as well as receptor internalization by the endomembrane system culminating in uptake of the vitamin D3-VDR-importin-4 complex into the nucleus. PMID:27369077

  14. Characterization of the haem-uptake system of the equine pathogen Streptococcus equi subsp. equi.

    PubMed

    Meehan, Mary; Burke, Fiona M; Macken, Susan; Owen, Peter

    2010-06-01

    Streptococcus equi possesses a haem-uptake system homologous to that of Streptococcus pyogenes and Streptococcus zooepidemicus. The system consists of two ligand-binding proteins (Shr and Shp) and proteins (HtsA-C) with homology to an ABC transporter. The haem-uptake system of S. equi differs from that of S. pyogenes and S. zooepidemicus in that Shr is truncated by two-thirds. This study focused on the SeShr, SeShp and SeHtsA proteins of S. equi. Analysis of shr, shp and shphtsA knockout mutants showed that all three proteins were expressed in vitro and that expression was upregulated under conditions of iron limitation. SeShr possesses no membrane-/cell wall-spanning sequences and was shown to be secreted. Both SeShp and SeHtsA were confirmed to be envelope-associated. Recombinant SeShp and SeHtsA proteins have been previously shown to bind haem and SeHtsA could capture haem from SeShp. This report extends these studies and shows that both SeShp and SeHtsA can sequester haem from haemoglobin but not from haemoglobin-haptoglobin complexes. Like full-length Shr, SeShr possesses haemoglobin and haemoglobin-haptoglobin binding ability but unlike full-length Shr, it lacks haem- or fibronectin-binding capabilities. Analysis of SeShr truncates showed that residues within and upstream of the near transporter (NEAT) domain are required for this ligand binding. Structural predictions suggest that truncation of NEAT1 in SeShr accounts for its impaired ability to bind haem. Haem and haemoglobin restored to almost normal the impaired growth rates of wild-type S. equi cultured under iron-limiting conditions. However, no difference in the growth rates of wild-type and mutants could be detected under the in vitro growth conditions tested. PMID:20223800

  15. Trace element uptake by Eleocharis equisetina (spike rush) in an abandoned acid mine tailings pond, northeastern Australia: implications for land and water reclamation in tropical regions.

    PubMed

    Lottermoser, Bernd G; Ashley, Paul M

    2011-10-01

    This study was conducted to determine the uptake of trace elements by the emergent wetland plant species Eleocharis equisetina at the historic Jumna tin processing plant, tropical Australia. The perennial emergent sedge was found growing in acid waters (pH 2.45) and metal-rich tailings (SnAsCuPbZn). E. equisetina displayed a pronounced acid tolerance and tendency to exclude environmentally significant elements (Al, As, Cd, Ce, Co, Cu, Fe, La, Ni, Pb, Se, Th, U, Y, Zn) from its above-substrate biomass. This study demonstrates that geobotanical and biogeochemical examinations of wetland plants at abandoned mined lands of tropical areas can reveal pioneering, metal-excluding macrophytes. Such aquatic macrophytes are of potential use in the remediation of acid mine waters and sulfidic tailings and the reclamation of disturbed acid sulfate soils in subtropical and tropical regions. PMID:21550704

  16. Mouse Strain Impacts Fatty Acid Uptake and Trafficking in Liver, Heart, and Brain: A Comparison of C57BL/6 and Swiss Webster Mice.

    PubMed

    Seeger, D R; Murphy, E J

    2016-05-01

    C57BL/6 and Swiss Webster mice are used to study lipid metabolism, although differences in fatty acid uptake between these strains have not been reported. Using a steady state kinetic model, [1-(14)C]16:0, [1-(14)C]20:4n-6, or [1-(14)C]22:6n-3 was infused into awake, adult male mice and uptake into liver, heart, and brain determined. The integrated area of [1-(14)C]20:4n-6 in plasma was significantly increased in C57BL/6 mice, but [1-(14)C]16:0 and [1-(14)C]22:6n-3 were not different between groups. In heart, uptake of [1-(14)C]20:4n-6 was increased 1.7-fold in C57BL/6 mice. However, trafficking of [1-(14)C]22:6n-3 into the organic fraction of heart was significantly decreased 33 % in C57BL/6 mice. Although there were limited differences in fatty acid tracer trafficking in liver or brain, [1-(14)C]16:0 incorporation into liver neutral lipids was decreased 18 % in C57BL/6 mice. In heart, the amount of [1-(14)C]16:0 and [1-(14)C]22:6n-3 incorporated into total phospholipids were decreased 45 and 49 %, respectively, in C57BL/6 mice. This was accounted for by a 53 and 37 % decrease in [1-(14)C]16:0 and 44 and 52 % decrease in [1-(14)C]22:6n-3 entering ethanolamine glycerophospholipids and choline glycerophospholipids, respectively. In contrast, there was a significant increase in [1-(14)C]20:4n-6 esterification into all heart phospholipids of C57BL/6 mice. Although changes in uptake were limited to heart, several significant differences were found in fatty acid trafficking into heart, liver, and brain phospholipids. In summary, our data demonstrates differences in tissue fatty acid uptake and trafficking between mouse strains is an important consideration when carrying out fatty acid metabolic studies. PMID:26797754

  17. Postprandial fatty acid uptake and adipocyte remodeling in angiotensin type 2 receptor-deficient mice fed a high-fat/high-fructose diet.

    PubMed

    Noll, Christophe; Labbé, Sébastien M; Pinard, Sandra; Shum, Michael; Bilodeau, Lyne; Chouinard, Lucie; Phoenix, Serge; Lecomte, Roger; Carpentier, André C; Gallo-Payet, Nicole

    2016-01-01

    The role of the angiotensin type-2 receptor in adipose physiology remains controversial. The aim of the present study was to demonstrate whether genetic angiotensin type-2 receptor-deficiency prevents or worsens metabolic and adipose tissue morphometric changes observed following a 6-week high-fat/high-fructose diet with injection of a small dose of streptozotocin. We compared tissue uptake of nonesterified fatty acid and dietary fatty acid in wild-type and angiotensin type-2 receptor-deficient mice by using the radiotracer 14(R,S)-[(1) (8)F]-fluoro-6-thia-heptadecanoic acid in mice fed a standard or high-fat diet. Postprandial fatty acid uptake in the heart, liver, skeletal muscle, kidney and adipose tissue was increased in wild-type mice after a high-fat diet and in angiotensin type-2 receptor-deficient mice on both standard and high-fat diets. Compared to the wild-type mice, angiotensin type-2 receptor-deficient mice had a lower body weight, an increase in fasting blood glucose and a decrease in plasma insulin and leptin levels. Mice fed a high-fat diet exhibited increased adipocyte size that was prevented by angiotensin type-2 receptor-deficiency. Angiotensin type-2 receptor-deficiency abolished the early hypertrophic adipocyte remodeling induced by a high-fat diet. The small size of adipocytes in the angiotensin type-2 receptor-deficient mice reflects their inability to store lipids and explains the increase in fatty acid uptake in non-adipose tissues. In conclusion, a genetic deletion of the angiotensin type-2 receptor is associated with metabolic dysfunction of white adipose depots, and indicates that adipocyte remodeling occurs before the onset of insulin resistance in the high-fat fed mouse model. PMID:27144096

  18. Investigating the Uptake Mechanisms of Hydrogen Peroxide to Single and Polycrystalline Ice with a Novel Flow Tube System

    NASA Astrophysics Data System (ADS)

    Hong, Angela; Ammann, Markus; Bartels-Rausch, Thorsten

    2016-04-01

    Air-ice chemical interactions are important for describing the distribution and subsequent chemical fate of trace atmospheric gases within ice and snow and determining the oxidative capacities of these environments. The nature of this interaction is governed by a compound's physicochemical properties as well as ice microstructure. Hydrogen peroxide (H2O2), a reservoir of HOx radicals in the atmosphere and an important chromophore in snow and ice, is a trace gas that demonstrates complex uptake behaviour to frozen aqueous media by the reversible, fast adsorption to the air-ice interface, aggregation, and lateral interactions, and a slower process, ostensibly via uptake into the bulk. However, the exact mechanism and kinetics for the slow uptake of H2O2 and the size of this reservoir is unknown. It is important to describe and quantify this loss term, over environmentally-relevant timescales, accommodation of H2O2 into the bulk may be the dominant process which controls the composition and chemistry of the snow and overlying atmosphere. We hypothesize that the slow uptake of H2O2 occurs by diffusion into the grain boundaries of ice. To provide mechanistic insight to the macroscopic phenomenon of atmospheric gas uptake to ice, and discern various mechanisms including adsorption to air-ice interface and accommodation into the bulk through uptake into grain boundaries, we design, machine, and validate a novel flow reactor system featuring a Drilled Ice Flow Tube (DIFT). Our flow reactor system is uniquely suited to testing these uptake mechanisms: by controlling the degree of grain boundaries present in the DIFT (ie. monocrystalline or polycrystalline), we can directly observe the effect of the ice microstructure on the adsorptive and bulk uptake of trace atmospheric gases over long timescales (eg. on the order of hours). Here, we describe method development of the DIFT and demonstrate using polarised microscopy imagery that our experimental set-up allows for the direct

  19. Identification and Characterization of the Dicarboxylate Uptake System DccT in Corynebacterium glutamicum▿

    PubMed Central

    Youn, Jung-Won; Jolkver, Elena; Krämer, Reinhard; Marin, Kay; Wendisch, Volker F.

    2008-01-01

    Many bacteria can utilize C4-carboxylates as carbon and energy sources. However, Corynebacterium glutamicum ATCC 13032 is not able to use tricarboxylic acid cycle intermediates such as succinate, fumarate, and l-malate as sole carbon sources. Upon prolonged incubation, spontaneous mutants which had gained the ability to grow on succinate, fumarate, and l-malate could be isolated. DNA microarray analysis showed higher mRNA levels of cg0277, which subsequently was named dccT, in the mutants than in the wild type, and transcriptional fusion analysis revealed that a point mutation in the promoter region of dccT was responsible for increased expression. The overexpression of dccT was sufficient to enable the C. glutamicum wild type to grow on succinate, fumarate, and l-malate as the sole carbon sources. Biochemical analyses revealed that DccT, which is a member of the divalent anion/Na+ symporter family, catalyzes the effective uptake of dicarboxylates like succinate, fumarate, l-malate, and likely also oxaloacetate in a sodium-dependent manner. PMID:18658264

  20. Fur-Regulated Iron Uptake System of Edwardsiella ictaluri and Its Influence on Pathogenesis and Immunogenicity in the Catfish Host

    PubMed Central

    Golden, Greg; Wanda, Soo-Young; Curtiss, Roy

    2012-01-01

    The ability of bacterial pathogens to take up iron from the host during infection is necessary for their multiplication within the host. However, host high-affinity iron binding proteins limit levels of free iron in fluids and tissues. To overcome this deficiency of iron during infection, bacterial pathogens have developed iron uptake systems that are upregulated in the absence of iron, typically tightly controlled by the ferric uptake regulator (Fur) protein. The iron uptake system of Edwardsiella ictaluri, a host-restricted pathogen of channel catfish (Ictalurus punctatus) and the main pathogen of this fish in aquaculture, is unknown. Here we describe the E. ictaluri Fur protein, the iron uptake machinery controlled by Fur, and the effects of fur gene deletion on virulence and immunogenicity in the fish host. Analysis of the E. ictaluri Fur protein shows that it lacks the N-terminal region found in the majority of pathogen-encoded Fur proteins. However, it is fully functional in regulated genes encoding iron uptake proteins. E. ictaluri grown under iron-limited conditions upregulates an outer membrane protein (HemR) that shows heme-hemoglobin transport activity and is tightly regulated by Fur. In vivo studies showed that an E. ictaluri Δfur mutant is attenuated and immune protective in zebrafish (Danio rerio) and catfish (Ictalurus punctatus), triggering systemic immunity. We conclude that an E. ictaluri Δfur mutant could be an effective component of an immersion-oral vaccine for the catfish industry. PMID:22615248

  1. 21 CFR 862.1509 - Methylmalonic acid (nonquantitative) test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Methylmalonic acid (nonquantitative) test system... Test Systems § 862.1509 Methylmalonic acid (nonquantitative) test system. (a) Identification. A methylmalonic acid (nonquantitative) test system is a device intended to identify methylmalonic acid in...

  2. 21 CFR 862.1509 - Methylmalonic acid (nonquantitative) test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Methylmalonic acid (nonquantitative) test system... Test Systems § 862.1509 Methylmalonic acid (nonquantitative) test system. (a) Identification. A methylmalonic acid (nonquantitative) test system is a device intended to identify methylmalonic acid in...

  3. 21 CFR 862.1509 - Methylmalonic acid (nonquantitative) test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Methylmalonic acid (nonquantitative) test system... Test Systems § 862.1509 Methylmalonic acid (nonquantitative) test system. (a) Identification. A methylmalonic acid (nonquantitative) test system is a device intended to identify methylmalonic acid in...

  4. 21 CFR 862.1509 - Methylmalonic acid (nonquantitative) test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Methylmalonic acid (nonquantitative) test system... Test Systems § 862.1509 Methylmalonic acid (nonquantitative) test system. (a) Identification. A methylmalonic acid (nonquantitative) test system is a device intended to identify methylmalonic acid in...

  5. 21 CFR 862.1795 - Vanilmandelic acid test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Vanilmandelic acid test system. 862.1795 Section... Systems § 862.1795 Vanilmandelic acid test system. (a) Identification. A vanilmandelic acid test system is a device intended to measure vanilmandelic acid in urine. Measurements of vanilmandelic...

  6. 21 CFR 862.1795 - Vanilmandelic acid test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Vanilmandelic acid test system. 862.1795 Section... Systems § 862.1795 Vanilmandelic acid test system. (a) Identification. A vanilmandelic acid test system is a device intended to measure vanilmandelic acid in urine. Measurements of vanilmandelic...

  7. Contribution of C3 carboxylation to the circadian rhythm of carbon dioxide uptake in a Crassulacean acid metabolism plant Kalanchoë daigremontiana.

    PubMed

    Wyka, Tomasz P; Lüttge, Ulrich E

    2003-05-01

    During the endogenous circadian rhythm of carbon dioxide uptake in continuous light by a Crassula cean acid metabolism plant, Kalanchoë daigremontiana, the two carboxylating enzymes, phosphoenolpyruvate carboxylase (PEPC) and ribulose 1,5 bisphosphate carboxylase/oxygenase (Rubisco), are active simultaneously, although, until now, only the role of PEPC in generating the rhythm has been acknowledged. According to the established model, the rhythm is primarily regulated at the PEPC activity level, modulated by periodic compartmentation of its inhibitor, malate, in the vacuole and controlled by tension/relaxation of the tonoplast. However, the circadian accumulation of malic acid (the main indicator of PEPC activity) dampened significantly within the first few periods without affecting the rhythm's amplitude. Moreover, the amount of malate accumulated during a free-running oscillation was several-fold lower than the amount expected if PEPC were the key carboxylating enzyme, based on a 1:1 stoichiometry of CO(2) and malate. Together with the observation that rates of CO(2) uptake under continuous light were higher than in darkness, the evidence shows that C(3) carboxylation greatly contributes to the generation of rhythmic CO(2) uptake in continuous light in this 'obligate' CAM plant. Because the shift from predominantly CAM to predominantly C(3) carboxylation is smooth and does not distort the trajectory of the rhythm, its control probably arises from a robust network of oscillators, perhaps also involving stomata. PMID:12709493

  8. Determining the functional role of waterborne amino acid uptake in hagfish nutrition: a constitutive pathway when fasting or a supplementary pathway when feeding?

    PubMed

    Glover, Chris N; Blewett, Tamzin A; Wood, Chris M

    2016-10-01

    Hagfish are unique among aquatic "vertebrates" in their ability to absorb amino acids directly from the water via skin and gill epithelia, but it is unknown whether this phenomenon extends beyond a few studied substrates; what effect fed state has on absorption; and what functional role this may play in hagfish nutrition. Using in vivo and in vitro transport assays, uptake and tissue distribution of the waterborne amino acids L-alanine, L-lysine, and L-phenylalanine were examined as a function of fed state. All three amino acids were shown to be taken up from the water (lysine and phenylalanine for the first time). Following immersion in radiolabelled solutions for 24 h, phenylalanine was the amino acid that accumulated at the highest levels in almost all tissues, with the highest accumulation noted in red blood cells and bile, followed by gill and liver. In general, tissues of fed hagfish displayed a significantly reduced phenylalanine accumulation compared to tissues of hagfish fasted for 3 weeks. An in vitro assay showed that phenylalanine was transported across the skin at the highest rate, with the uptake of lysine occurring at the lowest rate. Feeding status had no significant effect on in vitro transport. These data indicate that dissolved organic nutrients are a significant source of nutrition to hagfish, and may be relatively more important during periods of fasting than during periods of feeding when immersed in decaying carcasses. PMID:27215782

  9. Calcium sensor kinase activates potassium uptake systems in gland cells of Venus flytraps.

    PubMed

    Scherzer, Sönke; Böhm, Jennifer; Krol, Elzbieta; Shabala, Lana; Kreuzer, Ines; Larisch, Christina; Bemm, Felix; Al-Rasheid, Khaled A S; Shabala, Sergey; Rennenberg, Heinz; Neher, Erwin; Hedrich, Rainer

    2015-06-01

    The Darwin plant Dionaea muscipula is able to grow on mineral-poor soil, because it gains essential nutrients from captured animal prey. Given that no nutrients remain in the trap when it opens after the consumption of an animal meal, we here asked the question of how Dionaea sequesters prey-derived potassium. We show that prey capture triggers expression of a K(+) uptake system in the Venus flytrap. In search of K(+) transporters endowed with adequate properties for this role, we screened a Dionaea expressed sequence tag (EST) database and identified DmKT1 and DmHAK5 as candidates. On insect and touch hormone stimulation, the number of transcripts of these transporters increased in flytraps. After cRNA injection of K(+)-transporter genes into Xenopus oocytes, however, both putative K(+) transporters remained silent. Assuming that calcium sensor kinases are regulating Arabidopsis K(+) transporter 1 (AKT1), we coexpressed the putative K(+) transporters with a large set of kinases and identified the CBL9-CIPK23 pair as the major activating complex for both transporters in Dionaea K(+) uptake. DmKT1 was found to be a K(+)-selective channel of voltage-dependent high capacity and low affinity, whereas DmHAK5 was identified as the first, to our knowledge, proton-driven, high-affinity potassium transporter with weak selectivity. When the Venus flytrap is processing its prey, the gland cell membrane potential is maintained around -120 mV, and the apoplast is acidified to pH 3. These conditions in the green stomach formed by the closed flytrap allow DmKT1 and DmHAK5 to acquire prey-derived K(+), reducing its concentration from millimolar levels down to trace levels. PMID:25997445

  10. Identification and Characterization of the Nickel Uptake System for Urease Biogenesis in Streptococcus salivarius 57.I

    PubMed Central

    Chen, Yi-Ywan M.; Burne, Robert A.

    2003-01-01

    Ureases are multisubunit enzymes requiring Ni2+ for activity. The low pH-inducible urease gene cluster in Streptococcus salivarius 57.I is organized as an operon, beginning with ureI, followed by ureABC (structural genes), and ureEFGD (accessory genes). Urease biogenesis also requires a high-affinity Ni2+ uptake system. By searching the partial genome sequence of a closely related organism, Streptococcus thermophilus LMG18311, three open reading frame (ORFs) homologous to those encoding proteins involved in cobalamin biosynthesis and cobalt transport (cbiMQO) were identified immediately 3′ to the ure operon. To determine whether these genes were involved in urease biogenesis by catalyzing Ni2+ uptake in S. salivarius, regions 3′ to ureD were amplified by PCRs from S. salivarius by using primers identical to the S. thermophilus sequences. Sequence analysis of the products revealed three ORFs. Reverse transcriptase PCR was used to demonstrate that the ORFs are transcribed as part of the ure operon. Insertional inactivation of ORF1 with a polar kanamycin marker completely abolished urease activity and the ability to accumulate 63Ni2+ during growth. Supplementation of the growth medium with NiCl2 at concentrations as low as 2.5 μM partially restored urease activity in the mutant. Both wild-type and mutant strains showed enhanced urease activity when exogenous Ni2+ was provided at neutral pH. Enhancement of urease activity by adding nickel was regulated at the posttranslational level. Thus, ORF1, ORF2, and ORF3 are part of the ure operon, and these genes, designated ureM, ureQ, and ureO, respectively, likely encode a Ni2+-specific ATP-binding cassette transporter. PMID:14617641

  11. Calcium sensor kinase activates potassium uptake systems in gland cells of Venus flytraps

    PubMed Central

    Scherzer, Sönke; Böhm, Jennifer; Krol, Elzbieta; Shabala, Lana; Kreuzer, Ines; Larisch, Christina; Bemm, Felix; Al-Rasheid, Khaled A. S.; Shabala, Sergey; Rennenberg, Heinz; Neher, Erwin; Hedrich, Rainer

    2015-01-01

    The Darwin plant Dionaea muscipula is able to grow on mineral-poor soil, because it gains essential nutrients from captured animal prey. Given that no nutrients remain in the trap when it opens after the consumption of an animal meal, we here asked the question of how Dionaea sequesters prey-derived potassium. We show that prey capture triggers expression of a K+ uptake system in the Venus flytrap. In search of K+ transporters endowed with adequate properties for this role, we screened a Dionaea expressed sequence tag (EST) database and identified DmKT1 and DmHAK5 as candidates. On insect and touch hormone stimulation, the number of transcripts of these transporters increased in flytraps. After cRNA injection of K+-transporter genes into Xenopus oocytes, however, both putative K+ transporters remained silent. Assuming that calcium sensor kinases are regulating Arabidopsis K+ transporter 1 (AKT1), we coexpressed the putative K+ transporters with a large set of kinases and identified the CBL9-CIPK23 pair as the major activating complex for both transporters in Dionaea K+ uptake. DmKT1 was found to be a K+-selective channel of voltage-dependent high capacity and low affinity, whereas DmHAK5 was identified as the first, to our knowledge, proton-driven, high-affinity potassium transporter with weak selectivity. When the Venus flytrap is processing its prey, the gland cell membrane potential is maintained around −120 mV, and the apoplast is acidified to pH 3. These conditions in the green stomach formed by the closed flytrap allow DmKT1 and DmHAK5 to acquire prey-derived K+, reducing its concentration from millimolar levels down to trace levels. PMID:25997445

  12. Exceptional gravimetric and volumetric CO2 uptake in a palladated NbO-type MOF utilizing cooperative acidic and basic, metal-CO2 interactions.

    PubMed

    Spanopoulos, I; Bratsos, I; Tampaxis, C; Vourloumis, D; Klontzas, E; Froudakis, G E; Charalambopoulou, G; Steriotis, T A; Trikalitis, P N

    2016-08-18

    A novel NbO-type MOF is reported based on a palladated organic linker, showing a remarkable gravimetric and volumetric CO2 uptake, reaching 201.8 cm(3) g(-1) (9.0 mmol g(-1), 39.7 wt%) and 187.8 cm(3) cm(-3) at 273 K and 1 bar, respectively. Accurate theoretical calculations revealed that the exceptional CO2 uptake is due to the combination of Lewis base Pd(ii)-CO2 (24.3 kJ mol(-1)) and Lewis acid Cu(ii)-CO2 (30.3 kJ mol(-1)) interactions, as well as synergistic pore size effects. PMID:27498783

  13. Acid mine water aeration and treatment system

    DOEpatents

    Ackman, Terry E.; Place, John M.

    1987-01-01

    An in-line system is provided for treating acid mine drainage which basically comprises the combination of a jet pump (or pumps) and a static mixer. The jet pump entrains air into the acid waste water using a Venturi effect so as to provide aeration of the waste water while further aeration is provided by the helical vanes of the static mixer. A neutralizing agent is injected into the suction chamber of the jet pump and the static mixer is formed by plural sections offset by 90 degrees.

  14. The group A streptococcal dipeptide permease (Dpp) is involved in the uptake of essential amino acids and affects the expression of cysteine protease.

    PubMed

    Podbielski, A; Leonard, B A

    1998-06-01

    The majority of characterized bacterial dipeptide permeases (Dpp) are membrane-associated complexes of five proteins belonging to the ABC-transporter family. They have been found to be involved in the uptake of essential amino acids, haem production, chemotaxis and sporulation. A 5.8 kb genomic DNA fragment of the serotype M49 group A streptococcal (GAS) strain CS101 was sequenced and found to contain five putative GAS Dpp genes (dppA to dppE). Deduced amino acid sequences exhibited 17-54% similarity to corresponding ABC-transporter sequences. The operon organization of the five genes was confirmed by transcriptional analysis, and a shorter, more abundant, dppA-only transcript was detected similar to that found in the GAS oligopeptide permease (Opp) system. Insertional inactivation was used to create serotype M2 and M49 strains that did not express the dppD and dppEATPase genes or nearly the entire operon. In feeding experiments with di- to hexapeptides, the wild-type strain grew with each peptide tested. The dpp mutants were unable to grow on dipeptides, whereas hexapeptides did not sustain the growth of opp mutants. Expression of the dpp operon was induced approximately fourfold in late exponential growth phase. In addition, a striking increase in the dppA to dppA-E ratio from 5:1 to more than 20:1 occurred during late exponential growth phase in complex medium. Growth in chemically defined medium (CDM) supplemented with various dipeptides specifically induced the expression of dpp and reduced both the dppA to dppA-E and oppA to oppA-F mRNA ratios. Expression of the virulence factor SpeB (major cysteine protease) was reduced eightfold in dpp mutants, whereas dpp expression was decreased about fourfold in a Mga virulence regulator mutant. Taken together, these data indicate a correlation between levels of intracellular essential amino acids and the regulation of virulence factor expression. PMID:9680220

  15. Static magnetic field reduced exogenous oligonucleotide uptake by spermatozoa using magnetic nanoparticle gene delivery system

    NASA Astrophysics Data System (ADS)

    Katebi, Samira; Esmaeili, Abolghasem; Ghaedi, Kamran

    2016-03-01

    Spermatozoa could introduce exogenous oligonucleotides of interest to the oocyte. The most important reason of low efficiency of sperm mediated gene transfer (SMGT) is low uptake of exogenous DNA by spermatozoa. The aim of this study was to evaluate the effects of static magnetic field on exogenous oligonucleotide uptake of spermatozoa using magnetofection method. Magnetic nanoparticles (MNPs) associated with the labeled oligonucleotides were used to increase the efficiency of exogenous oligonucleotide uptake by rooster spermatozoa. We used high-field/high-gradient magnet (NdFeB) to enhance and accelerate exogenous DNA sedimentation at the spermatozoa surface. Flow cytometry analysis was performed to measure viability and percentage of exogenous oligonucleotide uptake by sperm. Flow cytometry analysis showed a significant increase in exogenous oligonucleotide uptake by rooster spermatozoa (P<0.001) when spermatozoa were incubated in exogenous oligonucleotide solution and MNPs. However, by applying static magnetic field during magnetofection method, a significant decrease in exogenous oligonucleotide uptake was observed (P<0.05). Findings of this study showed that MNPs were effective to increase exogenous oligonucleotide uptake by rooster spermatozoa; however unlike others studies, static magnetic field, was not only ineffective to enhance exogenous oligonucleotide uptake by rooster spermatozoa but also led to reduction in efficiency of magnetic nanoparticles in gene transfer.

  16. A Highly Conserved Bacterial D-Serine Uptake System Links Host Metabolism and Virulence.

    PubMed

    Connolly, James P R; Gabrielsen, Mads; Goldstone, Robert J; Grinter, Rhys; Wang, Dai; Cogdell, Richard J; Walker, Daniel; Smith, David G E; Roe, Andrew J

    2016-01-01

    The ability of any organism to sense and respond to challenges presented in the environment is critically important for promoting or restricting colonization of specific sites. Recent work has demonstrated that the host metabolite D-serine has the ability to markedly influence the outcome of infection by repressing the type III secretion system of enterohaemorrhagic Escherichia coli (EHEC) in a concentration-dependent manner. However, exactly how EHEC monitors environmental D-serine is not understood. In this work, we have identified two highly conserved members of the E. coli core genome, encoding an inner membrane transporter and a transcriptional regulator, which collectively help to "sense" levels of D-serine by regulating its uptake from the environment and in turn influencing global gene expression. Both proteins are required for full expression of the type III secretion system and diversely regulated prophage-encoded effector proteins demonstrating an important infection-relevant adaptation of the core genome. We propose that this system acts as a key safety net, sampling the environment for this metabolite, thereby promoting colonization of EHEC to favorable sites within the host. PMID:26727373

  17. The Sus operon: a model system for starch uptake by the human gut Bacteroidetes.

    PubMed

    Foley, Matthew H; Cockburn, Darrell W; Koropatkin, Nicole M

    2016-07-01

    Resident bacteria in the densely populated human intestinal tract must efficiently compete for carbohydrate nutrition. The Bacteroidetes, a dominant bacterial phylum in the mammalian gut, encode a plethora of discrete polysaccharide utilization loci (PULs) that are selectively activated to facilitate glycan capture at the cell surface. The most well-studied PUL-encoded glycan-uptake system is the starch utilization system (Sus) of Bacteroides thetaiotaomicron. The Sus includes the requisite proteins for binding and degrading starch at the surface of the cell preceding oligosaccharide transport across the outer membrane for further depolymerization to glucose in the periplasm. All mammalian gut Bacteroidetes possess analogous Sus-like systems that target numerous diverse glycans. In this review, we discuss what is known about the eight Sus proteins of B. thetaiotaomicron that define the Sus-like paradigm of nutrient acquisition that is exclusive to the Gram-negative Bacteroidetes. We emphasize the well-characterized outer membrane proteins SusDEF and the α-amylase SusG, each of which have unique structural features that allow them to interact with starch on the cell surface. Despite the apparent redundancy in starch-binding sites among these proteins, each has a distinct role during starch catabolism. Additionally, we consider what is known about how these proteins dynamically interact and cooperate in the membrane and propose a model for the formation of the Sus outer membrane complex. PMID:27137179

  18. Nonrecirculating hydroponic systems suitable for uptake studies at very low nutrient concentrations

    SciTech Connect

    Gutschick, V.P.; Kay, L.E. )

    1991-04-01

    The authors describe the mechanical, electronic, hydraulic, and structural design of a nonrecirculating hydroponic system. The system is particularly suited to sutides at very low nutrient concentratons, for which on-line concentration monitoring methods either do not exist or are costly and limited to monitoring relatively few indivitual plants. Solutions are mised automatically to chosen concentrations, which can be set differently for every pump fed from a master supply of deionized water and nutrient concentrates. Pumping rates can be varied over a 50-fold range, up to 400 liters per day, which suffices to maintain a number of large, post-seedling plants in rapid growth at (sub)micromolar levels of N and P. The outflow of each pump is divided among as many as 12 separate root chambers. In each changer one may monitor uptake by individual plant roots or segments thereof, by measuring nutrient depletion in batch samples of solution. The system is constructed from nontoxic materials that do not adsorb nutrient ions; no transient shifts of nitrate and phosphate concentrations are observable at the submicromolar level. Nonrecirculaton of solution limits porblems of pH shifts, microbial contamination, and cumulative imbalances in unmonitored nutrients. They note several disadvantages, principally related to high consumption of deionized water and solutes. The reciprocating pumps can be constructed inexpensively, particularly by the researcher. They also report previously unattainable control of passive temperature rise of chambers exposed to full sunlight, by use of white epoxy paint.

  19. A Highly Conserved Bacterial D-Serine Uptake System Links Host Metabolism and Virulence

    PubMed Central

    Connolly, James P. R.; Gabrielsen, Mads; Goldstone, Robert J.; Grinter, Rhys; Wang, Dai; Cogdell, Richard J.; Walker, Daniel; Smith, David G. E.; Roe, Andrew J.

    2016-01-01

    The ability of any organism to sense and respond to challenges presented in the environment is critically important for promoting or restricting colonization of specific sites. Recent work has demonstrated that the host metabolite D-serine has the ability to markedly influence the outcome of infection by repressing the type III secretion system of enterohaemorrhagic Escherichia coli (EHEC) in a concentration-dependent manner. However, exactly how EHEC monitors environmental D-serine is not understood. In this work, we have identified two highly conserved members of the E. coli core genome, encoding an inner membrane transporter and a transcriptional regulator, which collectively help to “sense” levels of D-serine by regulating its uptake from the environment and in turn influencing global gene expression. Both proteins are required for full expression of the type III secretion system and diversely regulated prophage-encoded effector proteins demonstrating an important infection-relevant adaptation of the core genome. We propose that this system acts as a key safety net, sampling the environment for this metabolite, thereby promoting colonization of EHEC to favorable sites within the host. PMID:26727373

  20. 21 CFR 862.1775 - Uric acid test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Uric acid test system. 862.1775 Section 862.1775....1775 Uric acid test system. (a) Identification. A uric acid test system is a device intended to measure uric acid in serum, plasma, and urine. Measurements obtained by this device are used in the...

  1. Uptake of Fluorescent Gentamicin by Peripheral Vestibular Cells after Systemic Administration

    PubMed Central

    Liu, Jianping; Kachelmeier, Allan; Dai, Chunfu; Li, Hongzhe; Steyger, Peter S.

    2015-01-01

    Objective In addition to cochleotoxicity, systemic aminoglycoside pharmacotherapy causes vestibulotoxicity resulting in imbalance and visual dysfunction. The underlying trafficking routes of systemically-administered aminoglycosides from the vasculature to the vestibular sensory hair cells are largely unknown. We investigated the trafficking of systemically-administered gentamicin into the peripheral vestibular system in C56Bl/6 mice using fluorescence-tagged gentamicin (gentamicin-Texas-Red, GTTR) imaged by scanning laser confocal microscopy to determine the cellular distribution and intensity of GTTR fluorescence in the three semicircular canal cristae, utricular, and saccular maculae at 5 time points over 4 hours. Results Low intensity GTTR fluorescence was detected at 0.5 hours as both discrete puncta and diffuse cytoplasmic fluorescence. The intensity of cytoplasmic fluorescence peaked at 3 hours, while punctate fluorescence was plateaued after 3 hours. At 0.5 and 1 hour, higher levels of diffuse GTTR fluorescence were present in transitional cells compared to hair cells and supporting cells. Sensory hair cells typically exhibited only diffuse cytoplasmic fluorescence at all time-points up to 4 hours in this study. In contrast, non-sensory cells rapidly exhibited both intense fluorescent puncta and weaker, diffuse fluorescence throughout the cytosol. The numbers and size of fluorescent puncta in dark cells and transitional cells increased over time. There is no preferential GTTR uptake by the five peripheral vestibular organs’ sensory cells. Control vestibular tissues exposed to Dulbecco’s phosphate-buffered saline or hydrolyzed Texas Red had negligible fluorescence. Conclusions All peripheral vestibular cells rapidly take up systemically-administered GTTR, reaching peak intensity 3 hours after injection. Sensory hair cells exhibited only diffuse fluorescence, while non-sensory cells displayed both diffuse and punctate fluorescence. Transitional cells may

  2. Secondary Organic Aerosol Formation from 2-Methyl-3-Buten-2-ol Photooxidation: Evidence of Acid-Catalyzed Reactive Uptake of Epoxides

    SciTech Connect

    Zhang, Haofei; Zhang, Zhenfa; Cui, Tianqu; Lin, Ying-Hsuan; Bhathela, Neil A.; Ortega, John; Worton, David; Goldstein, Allen H.; Guenther, Alex B.; Jimenez, Jose L.; Gold, Avram; Surratt, Jason D.

    2014-04-08

    Secondary organic aerosol (SOA) formation from 2-methyl-3-buten-2-ol (MBO) photooxidation has recently been observed in both field and laboratory studies. Similar to isoprene, MBO-derived SOA increases with elevated aerosol acidity in the absence of nitric oxide; therefore, an epoxide intermediate, (3,3-dimethyloxiran-2-yl)methanol (MBO epoxide) was synthesized and tentatively proposed here to explain this enhancement. In the present study, the potential of the synthetic MBO epoxide to form SOA via reactive uptake was systematically examined. SOA was observed only in the presence of acidic aerosols. Major SOA constituents, 2,3-dihydroxyisopentanol (DHIP) and MBO-derived organosulfate isomers, were chemically characterized in both laboratory-generated SOA and in ambient fine aerosols collected from the BEACHON-RoMBAS field campaign during summer 2011, where MBO emissions are substantial. Our results support epoxides as potential products of MBO photooxidation leading to formation of atmospheric SOA and suggest that reactive uptake of epoxides may generally explain acid enhancement of SOA observed from other biogenic hydrocarbons.

  3. Secretion of a pneumococcal type II secretion system pilus correlates with DNA uptake during transformation

    PubMed Central

    Balaban, Murat; Bättig, Patrick; Muschiol, Sandra; Tirier, Stephan M.; Wartha, Florian; Normark, Staffan; Henriques-Normark, Birgitta

    2014-01-01

    Streptococcus pneumoniae is a major human pathogen that successfully adapts to the host environment via an efficient uptake system for free DNA liberated from other organisms in the upper respiratory tract, facilitating immune evasion and drug resistance. Although the initial signaling events leading to pneumococcal competence for DNA transformation and the fate of DNA when it has been taken up have been extensively studied, the actual mechanism by which DNA in the environment may traverse the thick capsular and cell wall layers remains unknown. Here we visualize that induction of competence results in the formation of a native morphologically distinct pilus structure on the bacterial surface. This plaited pilus is encoded by the competence (com)G locus, and, after assembly, it is rapidly released into the surrounding medium. Heterologous pneumococcal pilus expression in Escherichia coli was obtained by replacing the pulE-K putative pilin genes of the Klebsiella oxytoca type II secretion system with the complete comG locus. In the pneumococcus, the coordinated secretion of pili from the cells correlates to DNA transformation. A model for DNA transformation is proposed whereby pilus assembly “drills” a channel across the thick cell wall that becomes transiently open by secretion of the pilus, providing the entry port for exogenous DNA to gain access to DNA receptors associated with the cytoplasmic membrane. PMID:24550320

  4. Endotoxin-stimulated macrophages decrease bile acid uptake in WIF-B cells, a rat hepatoma hybrid cell line.

    PubMed

    Sturm, E; Zimmerman, T L; Crawford, A R; Svetlov, S I; Sundaram, P; Ferrara, J L; Karpen, S J; Crawford, J M

    2000-01-01

    Endotoxemia leads to cytokine-mediated alterations of the hepatocellular sodium-taurocholate-cotransporting polypeptide (ntcp). We hypothesized that stimulated macrophages are essential transducers for down-regulating hepatocellular bile salt uptake in response to endotoxin (lipopolysaccharide [LPS]) exposure. Using an in vitro model, we exposed mouse macrophages (IC-21 cell line) to LPS for 24 hours. Concentrations of cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, and IL-6 increased 10.6-fold, 12.5-fold, and 444-fold, respectively, in LPS-conditioned IC-21 medium (CM) versus unconditioned IC-21 medium (UM). WIF-B rat hepatoma hybrid cells were incubated with either CM or UM or treated directly with medium containing recombinant TNF-alpha, IL-1beta, and IL-6. [(3)H]Taurocholate ([(3)H]TC) uptake decreased in WIF-B cells exposed to either TNF-alpha (54% of control), IL-1beta (78%), IL-6 (55%) as single additives, or in triple combination (TCC) (43%). A virtually identical decrease was observed after exposing WIF-B cells to CM (52%, P <.001). LPS had no direct effect on [(3)H]TC uptake. CM treatment did not decrease L-alanine transport in WIF-B cells. Blocking antibodies against TNF-alpha, IL-1beta, and IL-6 restored the diminished [(3)H]TC uptake in cells exposed to TCC and CM to 87% and 107% of controls, respectively. Northern blotting revealed that ntcp messenger RNA (mRNA) expression was significantly reduced in WIF-B cells after exposure to CM, and in primary rat hepatocytes exposed to CM or TNF-alpha (68%, 14%, and 29% of control, respectively). We conclude that macrophages and their ability to secrete the cytokines TNF-alpha, IL-1beta, and IL-6 may be essential in mediating the endotoxin-induced cholestatic effect of decreased hepatocellular bile salt uptake. PMID:10613737

  5. Poly(itaconic acid)-grafted chitosan adsorbents with different cross-linking for Pb(II) and Cd(II) uptake.

    PubMed

    Kyzas, George Z; Siafaka, Panoraia I; Lambropoulou, Dimitra A; Lazaridis, Nikolaos K; Bikiaris, Dimitrios N

    2014-01-14

    Two novel chitosan (CS) adsorbents were prepared in powder form, after modification with the grafting of itaconic acid (CS-g-IA) and cross-linking with either glutaraldehyde (CS-g-IA(G)) or epichlorohydrin (CS-g-IA(E)). Their adsorption properties were evaluated in batch experiments for Cd(II) or Pb(II) uptake. Characterization techniques were applied to the prepared adsorbents as swelling experiments, TGA, SEM, XRD, and FTIR. Adsorption mechanisms were suggested for different pH conditions. Various adsorption parameters were determined as the effect of pH, contact time, and temperature. The maximum adsorption capacities for Cd(II) uptake were 405 and 331 mg/g for CS-g-IA(G) and CS-g-IA(E), respectively, revealing the capacity enhancement after grafting (124 and 92 mg/g were the respective values before grafting, respectively). A similar grafting effect was observed for Pb(II) uptake, proving its adsorption effectiveness on the CS backbone. The reuse of adsorbents was tested with 20 adsorption-desorption cycles. PMID:24011255

  6. Inflammatory T cell responses rely on amino acid transporter ASCT2 facilitation of glutamine uptake and mTORC1 kinase activation

    PubMed Central

    Nakaya, Mako; Xiao, Yichuan; Zhou, Xiaofei; Chang, Jae-Hoon; Chang, Mikyoung; Cheng, Xuhong; Blonska, Marzenna; Lin, Xin; Sun, Shao-Cong

    2014-01-01

    Glutamine has been implicated as an immunomodulatory nutrient, but how glutamine uptake is mediated during T-cell activation is poorly understood. We have shown that naïve T-cell activation is coupled with rapid glutamine uptake, which depended on the amino acid transporter ASCT2. ASCT2 deficiency impaired the induction of T helper-1 (Th1) and Th17 cells and attenuated inflammatory T-cell responses in mouse models of immunity and autoimmunity. Mechanistically, ASCT2 was required for T cell receptor (TCR)-stimulated activation of the metabolic kinase mTORC1. We have further shown that TCR-stimulated glutamine uptake and mTORC1 activation also required a TCR signaling complex composed of the scaffold protein CARMA1, the adaptor molecule BCL10, and the paracaspase MALT1. This function was independent of IKK kinase, a major downstream target of the CARMA1 complex. These findings highlight a mechanism of T-cell activation involving ASCT2-dependent integration of the TCR signal and a metabolic signaling pathway. PMID:24792914

  7. Mannosylation Allows for Synergic (CD44/C-Type Lectin) Uptake of Hyaluronic Acid Nanoparticles in Dendritic Cells, but Only upon Correct Ligand Presentation.

    PubMed

    Gennari, Arianna; Pelliccia, Maria; Donno, Roberto; Kimber, Ian; Tirelli, Nicola

    2016-04-01

    The selective targeting of dendritic cells (DCs) can lead to more efficacious vaccines. Here, materials have been designed for a synergic DC targeting: interacting with CD44 through the use of hyaluronic acid (HA), and with mannose-binding lectins (typical DC pattern recognition receptors) through HA mannosylation. Negatively charged, HA-displaying nanoparticles are produced via polyelectrolyte complexation of (mannosylated) HA and high- or low- molecular-weight chitosan (CS, 36 and 656 kDa). Using CS36, HA is better exposed and the particles have a higher affinity for HA receptors; this means a higher number of receptors clustered around each particle and, due to the rather limited CD44 availability, an overall lower uptake per cell. Employing Langerhans-like XS106 cells, all particles show negligible toxicity or inflammatory activation. The cellular uptake kinetics are qualitatively similar to other leukocytic models and thus considered to be CD44-dominated; the uptake increases with increasing HA mannosylation and with the use of adjuvants (LPS, mannan) for CS36/HA but not for CS656//HA particles; this indicates that the interactions with mannose-binding receptors requires a correct ligand presentation, and only in that case can they be enhanced by appropriate adjuvants. In summary, mannose-binding receptors can be used to enhance the internalization of HA-based carriers, although this positive synergy depends on the mode of ligand presentation. PMID:26865006

  8. CONTINUOUS, AUTOMATED AND SIMULTANEOUS MEASUREMENT OF OXYGEN UPTAKE AND CARBON DIOXIDE EVOLUTION IN BIOLOGICAL SYSTEMS

    EPA Science Inventory

    Commercial respirometers are capable of continuously and automatically measuring oxygen uptake in bioreactors. A method for continuously and automatically measuring carbon dioxide evolution can be retrofitted to commercial respirometers. Continuous and automatic measurements of...

  9. Nnuclear uptake and retention of a synthetic progestin in the cardiovascular system of the baboon

    SciTech Connect

    Sheridan, P.J.; McGill, H.C. Jr.

    1984-06-01

    It has long been known that there is a sexual dimorphism in the incidence of coronary heart disease. This observation, together with more recent reports of increased cardiovascular disease associated with the use of oral contraceptives, led to a search for steroid receptors in the cardiovascular system. In this study the nuclear uptake and retention of a synthetic progestin was examined in the cardiovascular system of the baboons. Long term oophorectomized baboons were primed with estradiol benzoate for 3 days before the experiment (50 micrograms/kg, im) and adrenalectomized 2 days before the experiment. On the day of the experiment, the animals were injected under anesthesia with 2.5 micrograms/kg BW (/sup 3/H)ORG 2058 (16 alpha-ethyl-21-hydroxy-19-nor-(6,7-/sup 3/H)pregn-4-ene-3,20-dione) or with (/sup 3/H) ORG 2058 plus a 1000-fold excess of unlabeled progesterone (control). One hour after the injection, the animals were rapidly exsanguinated, and parts of the cardiovascular system were removed and processed for autoradiography. Localization of the synthetic progestin was found in nuclei of between 25-75% of all smooth muscle cells of the media of all arteries examined and to a lesser extent in the nuclei of the fibroblasts and others cells of the adventitia. Localization of the synthetic progestin in the heart was limited to approximately 1% of the myocardial cells and less than 5% of interstitial cell nuclei. The pattern of localization found differs from that for estrogen and androgen and suggests the possible presence of estrogen-independent progesterone receptors in smooth muscle cells of the media of the aorta and coronary arteries.

  10. Characterization of OpuA, a glycine-betaine uptake system of Lactococcus lactis.

    PubMed

    Bouvier, J; Bordes, P; Romeo, Y; Fourçans, A; Bouvier, I; Gutierrez, C

    2000-04-01

    A Lactococcus lactis glycine-betaine transport system was identified by functional complementation of an Escherichia coli proP proU mutant with a gene library from L. lactis sbsp. cremoris. The cloned locus forms an operon highly homologous to opuA, encoding a glycine-betaine uptake system of Bacillus subtilis. Disruption of opuA in L. lactis abolished protection by glycine-betaine against elevated osmolarity. OpuA belongs to the so-called "ABC transporters" family, which comprise an extracellularly localized substrate-binding protein. In B. subtilis OpuA system, this binding protein is a lipoprotein, attached to the external face of the cytoplasmic membrane by its lipidic moiety. In contrast, in the L. lactis opuA operon, and in other gram-positive homologues as well, a fusion between the gene encoding the integral membrane protein and the substrate-binding protein components gave rise to a hybrid protein presumably attaching the substrate-binding protein to the surface of the cell via its covalent link to the integral membrane component. Mapping of L. lactis opuA transcription start identified one mRNA, more abundant in cells grown at elevated osmolarity. Construction of an opuA-gusA fusion confirmed that opuA transcription is directed by a promoter osmotically inducible in L. lactis. When recombined upstream from a lac transcriptional fusion in the chromosome of E. coli, the opuA promoter appeared as very strong, and only poorly stimulated by elevated osmotic pressure, suggesting the existence of a specific machinery involved in the osmotic signal transduction in L. lactis. PMID:10939245

  11. The effect of gestational age on expression of genes involved in uptake, trafficking and synthesis of fatty acids in the rat placenta.

    PubMed

    Rodríguez-Cruz, Maricela; González, Raúl Sánchez; Maldonado, Jorge; López-Alarcón, Mardia; Bernabe-García, Mariela

    2016-10-15

    Gestation triggers a tight coordination among maternal tissues to provide fatty acids (FA) to the fetus through placental transport; however, there is insufficient evidence regarding regulation of proteins involved in placental transport of FA according to gestational age. The aim of this study was to determine the role of gestational age on the expression of genes involved in FA uptake, trafficking and synthesis in the rat placenta to support fetal demands. Gene expression of encoding proteins for placental transport and synthesis of FA was measured in placenta. Also, FA composition was measured in placenta, fetuses and newborns. mRNA expression of lipoprotein lipase (lpl) and fatp-1 (for uptake) was 4.4- and 1.43-fold higher, respectively, during late gestation than at P14, but expression of p-fabp-pm decreased 0.37-fold at late pregnancy in comparison with P14. Only mRNA fabp-4 member for trafficking of FA was 2.95-fold higher at late gestation than at P14. mRNA of fasn and elovl-6 participating in saturated FA and enzymes for the polyunsaturated FA synthesis were downregulated during late gestation and their regulator srebf-1c increased at P16. This study suggests that gestational age has an effect on expression of some genes involved in uptake, trafficking and synthesis of FA in the rat placenta; mRNA expression of lpl and, fatp-1 for uptake and fabp-4 implicated in trafficking was expressed at high levels at late gestation. In addition, placenta expresses the mRNAs involved in FA synthesis; these genes were expressed at low levels at late gestation. Additionally, mRNAs of Srebf-1c transcriptional regulator of desaturases and elongases was highly expressed during late gestation. Finally, these changes in the rat placenta allowed the placenta to partially supply saturated and monounsaturated FA to the fetus. PMID:27317891

  12. Nucleic acid detection systems for enteroviruses.

    PubMed Central

    Rotbart, H A

    1991-01-01

    The enteroviruses comprise nearly 70 human pathogens responsible for a wide array of diseases including poliomyelitis, meningitis, myocarditis, and neonatal sepsis. Current diagnostic tests for the enteroviruses are limited in their use by the slow growth, or failure to grow, of certain serotypes in culture, the antigenic diversity among the serotypes, and the low titer of virus in certain clinical specimens. Within the past 6 years, applications of molecular cloning techniques, in vitro transcription vectors, automated nucleic acid synthesis, and the polymerase chain reaction have resulted in significant progress toward nucleic acid-based detection systems for the enteroviruses that take advantage of conserved genomic sequences across many, if not all, serotypes. Similar approaches to the study of enteroviral pathogenesis have already produced dramatic advances in our understanding of how these important viruses cause their diverse clinical spectra. PMID:1649002

  13. Adjunctive β2-agonist treatment reduces glycogen independently of receptor-mediated acid α-glucosidase uptake in the limb muscles of mice with Pompe disease

    PubMed Central

    Farah, Benjamin L.; Madden, Lauran; Li, Songtao; Nance, Sierra; Bird, Andrew; Bursac, Nenad; Yen, Paul M.; Young, Sarah P.; Koeberl, Dwight D.

    2014-01-01

    Enzyme or gene replacement therapy with acid α-glucosidase (GAA) has achieved only partial efficacy in Pompe disease. We evaluated the effect of adjunctive clenbuterol treatment on cation-independent mannose-6-phosphate receptor (CI-MPR)-mediated uptake and intracellular trafficking of GAA during muscle-specific GAA expression with an adeno-associated virus (AAV) vector in GAA-knockout (KO) mice. Clenbuterol, which increases expression of CI-MPR in muscle, was administered with the AAV vector. This combination therapy increased latency during rotarod and wirehang testing at 12 wk, in comparison with vector alone. The mean urinary glucose tetrasaccharide (Glc4), a urinary biomarker, was lower in GAA-KO mice following combination therapy, compared with vector alone. Similarly, glycogen content was lower in cardiac and skeletal muscle following 12 wk of combination therapy in heart, quadriceps, diaphragm, and soleus, compared with vector alone. These data suggested that clenbuterol treatment enhanced trafficking of GAA to lysosomes, given that GAA was expressed within myofibers. The integral role of CI-MPR was demonstrated by the lack of effectiveness from clenbuterol in GAA-KO mice that lacked CI-MPR in muscle, where it failed to reverse the high glycogen content of the heart and diaphragm or impaired wirehang performance. However, the glycogen content of skeletal muscle was reduced by the addition of clenbuterol in the absence of CI-MPR, as was lysosomal vacuolation, which correlated with increased AKT signaling. In summary, β2-agonist treatment enhanced CI-MPR-mediated uptake and trafficking of GAA in mice with Pompe disease, and a similarly enhanced benefit might be expected in other lysosomal storage disorders.—Farah, B. L., Madden, L., Li, S., Nance, S., Bird, A., Bursac, N., Yen, P. M., Young, S. P., Koeberl, D. D. Adjunctive β2-agonist treatment reduces glycogen independently of receptor-mediated acid α-glucosidase uptake in the limb muscles of mice with

  14. Translocation of amino acids in the xylem of apple (Malus domestica Borkh.) trees in spring as a consequence of both N remobilization and root uptake.

    PubMed

    Malaguti, D; Millard, P; Wendler, R; Hepburn, A; Tagliavini, M

    2001-08-01

    Nitrogen is remobilized from storage for the growth of Malus domestica leaves each spring. Seasonal patterns of N translocation in the xylem sap as a consequence of remobilization were determined in 2-year-old 'Golden delicious' trees grafted on M9 rootstocks. The trees were grown in sand culture and (15)NH(4)(15)NO(3) at 10.4 atom% abundance supplied during August-September. The following year no further N was supplied and destructive harvests were taken during bud burst and leaf growth to determine the patterns of N remobilization together with the isolation of xylem sap for an analysis of their amino acid profiles and (15)N enrichments by GC-MS. The concentration of amino acids in the xylem sap rose following bud burst, peaked at full bloom and then fell again during petal fall and fruit set. The peak in amino acid concentration corresponded with the period when the rate of N remobilization was the fastest. The majority of labelled N was recovered in Asn, Gln + Glu and Asp demonstrating that they were being translocated as a consequence of remobilization. In a second experiment, 8-year-old trees growing in an orchard were fertilized with N either in the autumn or spring. Xylem sap samples were collected in the spring and early summer and, by comparison with the amino acid profiles recovered in trees from both treatments, Asn was identified as the main compound translocated as a consequence of both remobilization and root uptake of N, although there was evidence that root uptake of N occurred later. The data are discussed in relation to quantifying the internal cycling of N in trees. PMID:11479331

  15. Laboratory studies of the reactive uptake of biogenic species: Evidence for the direct polymerization of isoprene, terpenes and sesquiterpenes on acidic aerosols

    NASA Astrophysics Data System (ADS)

    Li, S.; Liggio, J.; Mihele, C.; Brook, J.

    2006-12-01

    Numerous studies on heterogeneous reactions have shown that polymerization of semi-volatile and volatile organic compounds occurs in aerosols. To date, most evidence suggests that gaseous hydrocarbon oxidation products containing carbonyl functionality are the prime candidates for these processes. Such processes involve primarily hydration, acetal formation, polymerization and aldol-condensation reactions, resulting in oligomer products of potential significance with respect to secondary organic aerosol formation (SOA). However, little information on the heterogeneous reactions of unsaturated hydrocarbons (olefins) is known. Given that biogenic species, many of them unsaturated, make up a considerable portion of hydrocarbons emitted globally, direct reactive uptake of these compounds on aerosols would also potentially be a major source of SOA. In the present study, individual biogenic hydrocarbons were exposed to pre-existing acidic sulfate aerosols within a 2 m3 Teflon reaction chamber under varying relative humidity conditions. An Aerosol Mass Spectrometer was used to quantify any subsequent increase in organic mass as a function of time, and to obtain information regarding the structure of products via aerosol mass spectra. A Proton Transfer Reaction Mass Spectrometer was used to measure the gas-phase concentrations of isoprene, terpenes (?-pinene, ?-pinene, limonene, and carene) and sesquiterpenes (?-caryophylene and humulene) in the reaction chamber. Results from these experiments show that a significant amount of these compounds are taken up by the acidic aerosols rapidly, in a polymerization process which was highly dependent on the particle acidity. This polymerization mechanism likely involves the oxygenation of the resulting polymers via acid catalyzed hydration. The uptake of the unsaturated hydrocarbons suggests that gas-phase oxidation of biogenics to condensable products is not the only route to SOA. Details of the polymerization and hydration

  16. Whole body synthesis rates of DHA from α-linolenic acid are greater than brain DHA accretion and uptake rates in adult rats[S

    PubMed Central

    Domenichiello, Anthony F.; Chen, Chuck T.; Trepanier, Marc-Olivier; Stavro, P. Mark; Bazinet, Richard P.

    2014-01-01

    Docosahexaenoic acid (DHA) is important for brain function, however, the exact amount required for the brain is not agreed upon. While it is believed that the synthesis rate of DHA from α-linolenic acid (ALA) is low, how this synthesis rate compares with the amount of DHA required to maintain brain DHA levels is unknown. The objective of this work was to assess whether DHA synthesis from ALA is sufficient for the brain. To test this, rats consumed a diet low in n-3 PUFAs, or a diet containing ALA or DHA for 15 weeks. Over the 15 weeks, whole body and brain DHA accretion was measured, while at the end of the study, whole body DHA synthesis rates, brain gene expression, and DHA uptake rates were measured. Despite large differences in body DHA accretion, there was no difference in brain DHA accretion between rats fed ALA and DHA. In rats fed ALA, DHA synthesis and accretion was 100-fold higher than brain DHA accretion of rats fed DHA. Also, ALA-fed rats synthesized approximately 3-fold more DHA than the DHA uptake rate into the brain. This work indicates that DHA synthesis from ALA may be sufficient to supply the brain. PMID:24212299

  17. Synthesis and characterization of poly(maleic acid)-grafted crosslinked chitosan nanomaterial with high uptake and selectivity for Hg(II) sorption.

    PubMed

    Ge, Huacai; Hua, Tingting

    2016-11-20

    Chitosan-poly(maleic acid) nanomaterial (PMACS) with the size of 400-900nm was synthesized by grafting poly(maleic acid) onto chitosan and then crosslinking with glutaraldehyde. The synthesis conditions were optimized. The structure and morphology of PMACS were characterized by FT-IR, XRD, SEM and TGA. PMACS was used to adsorb some heavy metal ions such as Hg(II), Pb(II), Cu(II), Cd(II), Co(II), and Zn(II). The results indicated that PMACS had selectivity for Hg(II) sorption. The effects of various variables for sorption of Hg(II) were further explored. The maximum capacity for Hg(II) sorption was found to be 1044mgg(-1) at pH 6.0, which could compare with the maximal value of the recently reported other sorbents. The sorption followed the pseudo-second-order kinetics and Langmuir isotherm models. The rising of temperature benefited the uptake and the sorption was a spontaneous chemical process. The sorbent could be reused with EDTA. Hence, the nanomaterial would be used as a selective and high uptake sorbent in the removal of Hg(II) from effluents. PMID:27561493

  18. Interplay between seven secondary metal uptake systems is required for full metal resistance of Cupriavidus metallidurans.

    PubMed

    Herzberg, M; Bauer, L; Kirsten, A; Nies, D H

    2016-03-01

    The beta-proteobacterium Cupriavidus metallidurans is able to grow in metal-contaminated environments due to having sophisticated metal efflux systems. Here, the contribution of all seven known secondary metal uptake systems (ZupT, PitA, CorA1, CorA2, CorA3, ZntB, HoxN) to metal resistance is characterized. In a strategic deletion approach, all ten double deletion mutants, a variety of triple and quadruple mutants, and from the Δ4 mutant (ΔzupT ΔcorA1 ΔcorA2 ΔcorA3) the mutants Δ5 (=Δ4 ΔpitA), Δ6 (=Δ4 ΔpitA ΔzntB), and finally Δ7 (ΔzupT ΔcorA1 ΔcorA2 ΔcorA3 ΔpitA ΔzntB ΔhoxN) were constructed. Metal resistance, metal content, and regulation of expression of these genes were characterized in these mutants. The ΔzupT single deletion strain exhibited an extended lag phase in Tris-buffered liquid mineral salts medium (TMM) compared to its parent strain AE104, indicating a decreased fitness level. Further deletions up to Δ6 did not influence growth in TMM without added metals but fitness of the Δ7 strain dropped to a lower level compared to Δ6, Δ5 and ΔzupT. The cells of the Δ7 multiple deletion strain still contained all essential metals, demonstrating that additional metal import systems must exist in C. metallidurans. PitA was an important contributor of metal:phosphate complexes to C. metallidurans. Up to Δ5 no evidence was found for increased expression of the transporter genes to recruit substitutes for the deleted importers. Only the hoxN-lacZ reporter gene fusion displayed a changed expression pattern in the Δ6 strain, indicating recruitment of HoxN. Metal resistance of the deletion strains decreased along the deletion series although all strains still contained metal efflux systems: up to the Δ6 mutant the overall fitness was kept at the ΔzupT mutant strain level at the cost of a diminished competence to handle μM concentrations of transition metals. Together, these data demonstrated an important contribution of the seven

  19. Factors Associated with Uptake of Visual Inspection with Acetic Acid (VIA) for Cervical Cancer Screening in Western Kenya

    PubMed Central

    Orang’o, Elkanah Omenge; Wachira, Juddy; Asirwa, Fredrick Chite; Busakhala, Naftali; Naanyu, Violet; Kisuya, Job; Otieno, Grieven; Keter, Alfred; Mwangi, Ann; Inui, Thomas

    2016-01-01

    Purpose Cervical cancer screening has been successful in reducing the rates of cervical cancer in developed countries, but this disease remains the leading cause of cancer deaths among women in sub-Saharan Africa. We sought to understand factors associated with limited uptake of screening services in our cervical cancer-screening program in Western Kenya. Participants and Methods Using items from a previously validated cancer awareness questionnaire repurposed for use in cervical cancer and culturally adapted for use in Kenya, we interviewed 2,505 women aged 18–55 years receiving care in gynecology clinics or seeking other services in 4 health facilities in Western Kenya between April 2014 and September 2014. We used logistic regression modeling to assess factors associated with uptake (or non-uptake), associated odds ratios (ORs) and the 95% confidence intervals (95% CI). Results Only two hundred and seventy-three women out of 2505 (11%) accepted VIA cervical cancer screening. Knowledge of just how women are screened for cervical cancer was significantly associated with reduced uptake of cervical cancer screening (OR: 0.53; CI 0.38–0.73) as was fear that screening would reveal a cancer (OR 0.70; CI 0.63–0.77), and reliance on prayer with the onset of illness (OR 0.43; CI 0.26–0.71). Participants who thought that one should get cervical cancer screening even if there were no symptoms were more than twice as likely to accept cervical cancer screening (OR 2.21; 95% CI 1.24–3.93). Older patients, patients living with HIV and women who do not know if bleeding immediately after sex might be a sign of cervical cancer were also more likely to accept screening (OR 1.03, CI 1.02–1.04; OR 1.78, CI 1.01–3.14; OR 2.39, CI 1.31–4.39, respectively). Conclusions In our population, a high percent of women knew that it is appropriate for all women to get cervical cancer screening, but only a small proportion of women actually got screening. There may be an

  20. Soil-based cycling and differential uptake of amino acids by three species of strawberry (Fragaria spp.) plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evidence is growing that amino acids can be an important source of plant N in nutrient limited natural ecosystems, but relatively little is known about the effect of agricultural management on soil amino acid pools and turnover. In order to determine the relative effects of soil type and management ...

  1. Introduction of an 8-Aminooctanoic Acid Linker Enhances the melanoma uptake of Tc-99m-labeled Lactam Bridge-Cyclized Alpha-MSH Peptide

    PubMed Central

    Guo, Haixun; Miao, Yubin

    2015-01-01

    The purpose of this study was to examine the effects of amino acid, hydrocarbon and polyethylene glycol (PEG) linkers on melanoma targeting and imaging properties of 99mTc-labeled lactam bridge-cyclized HYNIC-linker-Nle-CycMSHhex {hydrazinonicotinamide-linker-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2} peptides. Methods four novel peptides {HYNIC-GGGNle-CycMSHhex, HYNIC-GSGNle-CycMSHhex, HYNIC-PEG2Nle-CycMSHhex and HYNIC-AocNle-CycMSHhex} were designed and synthesized. The melanocortin-1 (MC1) receptor binding affinities of the peptides were determined in B16/F1 melanoma cells. The biodistribution of 99mTc(EDDA)-HYNIC-GGGNle-CycMSHhex, 99mTc(EDDA)-HYNIC-GSGNle-CycMSHhex, 99mTc(EDDA)-HYNIC-PEG2Nle-CycMSHhex and 99mTc(EDDA)-HYNIC-AocNle-CycMSHhex were determined in B16/F1 melanoma-bearing C57 mice at 2 h post-injection to select a lead peptide for further evaluation. The melanoma targeting and imaging properties of 99mTc(EDDA)-HYNIC-AocNle-CycMSHhex were further examined because of its high melanoma uptake. Results The IC50 values of HYNIC-GGGNle-CycMSHhex, HYNIC-GSGNle-CycMSHhex, HYNIC-PEG2Nle-CycMSHhex, and HYNIC-AocNle-CycMSHhex were 0.7 ± 0.1, 0.8 ± 0.09, 0.4 ± 0.08, and 0.3 ± 0.06 nM in B16/F1 melanoma cells, respectively. Among these four 99mTc-labeled peptides, 99mTc(EDDA)-HYNIC-AocNle-CycMSHhex displayed the highest melanoma uptake (22.3 ± 1.72% ID/g) at 2 h post-injection. 99mTc(EDDA)-HYNIC-AocNle-CycMSHhex exhibited high tumor to normal organ uptake ratios except for the kidneys. The tumor/kidney uptake ratios of 99mTc(EDDA)-HYNIC-AocNle-CycMSHhex were 3.29, 3.63 and 6.78 at 2, 4 and 24 h post-injection. The melanoma lesions were clearly visualized by single photon emission computed tomography (SPECT)/CT using 99mTc(EDDA)-HYNIC-AocNle-CycMSHhex as an imaging probe at 2 h post-injection. Conclusion High melanoma uptake and fast urinary clearance of 99mTc(EDDA)-HYNIC-AocNle-CycMSHhex highlighted its potential for metastatic melanoma detection in the future

  2. Investigations of the uptake of transuranic radionuclides by humic and fulvic acids chemically immobilized on silica gel and their competitive release by complexing agents

    SciTech Connect

    Bulman, R.A.; Szabo, G.; Clayton, R.F.; Clayton, C.R.

    1998-07-01

    The chemistry of the interactions of transuranic elements (TUs) with humic substances needs to be understood so that humate-mediated movement of transuranic radionuclides through the environment can be predicted. This paper reports the chemical immobilization on silica gel of humic and fulvic acids and evaluates the potential of these new materials for the retention of Pu and Am. In addition to the preparation of the foregoing immobilized humic substances, other low molecular weight metal-binding ligands have also been immobilized on silica gel to investigate the binding sites for transuranic elements (TUs) in humic substances. The X-ray photoelectron spectra (XPS) of Th(IV) complexed by humic acid and the immobilized humic acid are similar thus it appears that immobilization of humic acid does not generate any configurational changes in the Th(IV)-binding sites of the macromolecule. A variety of chelating agents partly mobilize these TUs sorbed on the solid phases. A batch method was used to determine the distribution coefficients (R{sub d}) of Pu and Am between the silica gels and aqueous solutions of phosphate and citrate. The effects of the immobilized ligands, the anions and pH in the solution on sorption were assessed. Distributed coefficients (R{sub d}) for the uptake of Pu and Am by these prepared solid phases are, in some cases, of a similar order of magnitude as those determined for soil and particles suspended in terrestrial surface waters.

  3. Using a Genome-Scale Metabolic Model of Enterococcus faecalis V583 To Assess Amino Acid Uptake and Its Impact on Central Metabolism

    PubMed Central

    Solheim, Margrete; van Grinsven, Koen W. A.; Olivier, Brett G.; Levering, Jennifer; Grosseholz, Ruth; Hugenholtz, Jeroen; Holo, Helge; Nes, Ingolf; Teusink, Bas; Kummer, Ursula

    2014-01-01

    Increasing antibiotic resistance in pathogenic bacteria necessitates the development of new medication strategies. Interfering with the metabolic network of the pathogen can provide novel drug targets but simultaneously requires a deeper and more detailed organism-specific understanding of the metabolism, which is often surprisingly sparse. In light of this, we reconstructed a genome-scale metabolic model of the pathogen Enterococcus faecalis V583. The manually curated metabolic network comprises 642 metabolites and 706 reactions. We experimentally determined metabolic profiles of E. faecalis grown in chemically defined medium in an anaerobic chemostat setup at different dilution rates and calculated the net uptake and product fluxes to constrain the model. We computed growth-associated energy and maintenance parameters and studied flux distributions through the metabolic network. Amino acid auxotrophies were identified experimentally for model validation and revealed seven essential amino acids. In addition, the important metabolic hub of glutamine/glutamate was altered by constructing a glutamine synthetase knockout mutant. The metabolic profile showed a slight shift in the fermentation pattern toward ethanol production and increased uptake rates of multiple amino acids, especially l-glutamine and l-glutamate. The model was used to understand the altered flux distributions in the mutant and provided an explanation for the experimentally observed redirection of the metabolic flux. We further highlighted the importance of gene-regulatory effects on the redirection of the metabolic fluxes upon perturbation. The genome-scale metabolic model presented here includes gene-protein-reaction associations, allowing a further use for biotechnological applications, for studying essential genes, proteins, or reactions, and the search for novel drug targets. PMID:25527553

  4. 2-Oxocarboxylic acids and function of pancreatic islets in obese–hyperglycaemic mice. Insulin secretion in relation to 45Ca uptake and metabolism

    PubMed Central

    Lenzen, Sigurd; Panten, Uwe

    1980-01-01

    The effects of aliphatic 2-oxocarboxylic acids, at concentrations of up to 40mm, on the function of pancreatic islets from ob/ob (obese–hyperglycaemic) mice were investigated. 1. 2-Oxopentanoate, dl-3-methyl-2-oxopentanoate, 4-methyl-2-oxopentanoate and 2-oxohexanoate all induced insulin release by isolated incubated islets and a biphasic insulin-secretory pattern in perfused mouse pancreas. The last two substances were similar in potency to glucose. Pyruvate, 2-oxobutyrate, 3-methyl-2-oxobutyrate and 2-oxo-octanoate did not induce insulin release significantly. 2. 2-Oxocarboxylic acids with significant insulin-secretory potency also induced significant 45Ca uptake by isolated incubated islets. 3. The rates of decarboxylation of [1-14C]pyruvate, 3-methyl-2-oxo[1-14C]butyrate and 4-methyl-2-oxo[1-14C]pentanoate were twice as high as the rates of oxidation of the corresponding U-14C-labelled compounds. However, whereas the rates of metabolism of labelled pyruvate and 3-methyl-2-oxobutyrate steadily increased over the concentration range 1–40mm, those of labelled 4-methyl-2-oxopentanoate and d-[U-14C]glucose levelled off at concentrations above 10mm. 4. Omission of 40CaCl2 from the incubation medium reduced the rate of oxidation of the insulin secretagogue [U-14C]4-methyl-2-oxopentanoate, but left that of the non-(insulin secretagogue) [U-14C]3-methyl-2-oxobutyrate unaffected. 5. Only glucose, and not pyruvate, 3-methyl-2-oxobutyrate and 4-methyl-2-oxopentanoate, significantly inhibited oxidation of endogenous fatty acids. 6. It is suggested that stimulus–secretion coupling and the resulting exocytosis of insulin in pancreatic β-cells may modulate both fuel oxidation and 45Ca uptake. PMID:6989358

  5. Dual Regulation of the Arabidopsis High-Affinity Root Iron Uptake System by Local and Long-Distance Signals1

    PubMed Central

    Vert, Grégory A.; Briat, Jean-François; Curie, Catherine

    2003-01-01

    Regulation of the root high-affinity iron uptake system by whole-plant signals was investigated at the molecular level in Arabidopsis, through monitoring FRO2 and IRT1 gene expression. These two genes encode the root ferric-chelate reductase and the high-affinity iron transporter, respectively, involved in the iron deficiency-induced uptake system. Recovery from iron-deficient conditions and modulation of apoplastic iron pools indicate that iron itself plays a major role in the regulation of root iron deficiency responses at the mRNA and protein levels. Split-root experiments show that the expression of IRT1 and FRO2 is controlled both by a local induction from the root iron pool and through a systemic pathway involving a shoot-borne signal, both signals being integrated to tightly control production of the root iron uptake proteins. We also show that IRT1 and FRO2 are expressed during the day and down-regulated at night and that this additional control is overruled by iron starvation, indicating that the nutritional status prevails on the diurnal regulation. Our work suggests, for the first time to our knowledge, that like in grasses, the root iron acquisition in strategy I plants may also be under diurnal regulation. On the basis of the new molecular insights provided in this study and given the strict coregulation of IRT1 and FRO2 observed, we present a model of local and long-distance regulation of the root iron uptake system in Arabidopsis. PMID:12805609

  6. Dual regulation of the Arabidopsis high-affinity root iron uptake system by local and long-distance signals.

    PubMed

    Vert, Grégory A; Briat, Jean-François; Curie, Catherine

    2003-06-01

    Regulation of the root high-affinity iron uptake system by whole-plant signals was investigated at the molecular level in Arabidopsis, through monitoring FRO2 and IRT1 gene expression. These two genes encode the root ferric-chelate reductase and the high-affinity iron transporter, respectively, involved in the iron deficiency-induced uptake system. Recovery from iron-deficient conditions and modulation of apoplastic iron pools indicate that iron itself plays a major role in the regulation of root iron deficiency responses at the mRNA and protein levels. Split-root experiments show that the expression of IRT1 and FRO2 is controlled both by a local induction from the root iron pool and through a systemic pathway involving a shoot-borne signal, both signals being integrated to tightly control production of the root iron uptake proteins. We also show that IRT1 and FRO2 are expressed during the day and down-regulated at night and that this additional control is overruled by iron starvation, indicating that the nutritional status prevails on the diurnal regulation. Our work suggests, for the first time to our knowledge, that like in grasses, the root iron acquisition in strategy I plants may also be under diurnal regulation. On the basis of the new molecular insights provided in this study and given the strict coregulation of IRT1 and FRO2 observed, we present a model of local and long-distance regulation of the root iron uptake system in Arabidopsis. PMID:12805609

  7. UPTAKE OF HEAVY METALS IN BATCH SYSTEMS BY A RECYCLED IRON-BEARING MATERIAL

    EPA Science Inventory

    An iron-bearing material deriving from surface finishing operations in the manufacturing of cast-iron components demonstrates potential for removal of heavy metals from aqueous waste streams. Batch isotherm and rate experiments were conducted for uptake of cadmium, zinc, and lead...

  8. Fatty acid oxidation: systems analysis and applications.

    PubMed

    Cintolesi, Angela; Rodríguez-Moyá, María; Gonzalez, Ramon

    2013-01-01

    Fatty acids (FAs) are essential components of cellular structure and energy-generating routes in living organisms. They exist in a variety of chemical configurations and functionalities and are catabolized by different oxidative routes, according to their structure. α- and ω-Oxidation are minor routes that occur only in eukaryotes, while β-oxidation is the major degradation route in eukaroytes and prokaryotes. These pathways have been characterized and engineered from different perspectives for industrial and biomedical applications. The severity of FA oxidation disorders in humans initially guided the study of FA metabolism at a molecular-level. On the other hand, recent advances in metabolic engineering and systems biology have powered the study of FA biosynthetic and catabolic routes in microorganisms at a systems-level. Several studies have proposed these pathways as platforms for the production of fuels and chemicals from biorenewable sources. The lower complexity of microbial systems has allowed a more comprehensive study of FA metabolism and has opened opportunities for a wider range of applications. Still, there is a need for techniques that facilitate the translation of high-throughput data from microorganisms to more complex eukaryotic systems in order to aid the development of diagnostic and treatment strategies for FA oxidation disorders. In addition, further systems biology analyses on human systems could also provide valuable insights on oxidation disorders. This article presents a comparison of the three main FA oxidative routes, systems biology analyses that have been used to study FA metabolism, and engineering efforts performed on microbial systems. PMID:23661533

  9. Effects of inorganic and organic amendments on the uptake of lead and trace elements by Brassica chinensis grown in an acidic red soil.

    PubMed

    Tang, Xianjin; Li, Xia; Liu, Xingmei; Hashmi, Muhammad Z; Xu, Jianming; Brookes, Philip C

    2015-01-01

    A greenhouse study was conducted to investigate the effects of inorganic (phosphate rock, single superphosphate and calcium magnesium phosphate) and organic amendments (peat, straw manure and pig manure) on the uptake of lead (Pb) and trace elements by Chinese Cabbage (Brassica chinensis) grown in an acidic red soil. The application of all organic amendments increased the soil pH while inorganic amendments such as single superphosphate did not. Both inorganic and organic amendments decreased the availability and uptake of Pb while the organic amendments were superior to the inorganic (phosphate) amendments in reducing the availability of the more labile (soluble and exchangeable Pb) forms of soil Pb. More Pb was taken up by roots than shoots with all soil amendments. Among the organic amendments, straw manure and pig manure caused the largest decrease in Pb availability at 456.5 and 457.3 mg kg(-1), respectively, when a high level of 30 g organic amendments kg(-1) was applied. The organic amendments greatly increased the fraction D targeted to Fe-Mn oxides bound Pb, and decreased the fraction A (water-soluble), B (exchangeable), and C (carbonate-bound), thereby decreasing the solubility and mobility of Pb in soil. The organic amendments also significantly improved the concentrations of Fe, Mn, Cu and Zn in the soil and shoots (except Fe in shoots and/or roots), which are essential for plant nutrition. The organic amendments of straw and pig manure lowered the availability and uptake of Pb but not that of other trace metals. Thus, these amendments have the potential to remediate Pb-contaminated soils in situ. PMID:24992219

  10. The Uptake of GABA in Trypanosoma cruzi.

    PubMed

    Galvez Rojas, Robert L; Ahn, Il-Young; Suárez Mantilla, Brian; Sant'Anna, Celso; Pral, Elizabeth Mieko Furusho; Silber, Ariel Mariano

    2015-01-01

    Gamma aminobutyric acid (GABA) is widely known as a neurotransmitter and signal transduction molecule found in vertebrates, plants, and some protozoan organisms. However, the presence of GABA and its role in trypanosomatids is unknown. Here, we report the presence of intracellular GABA and the biochemical characterization of its uptake in Trypanosoma cruzi, the etiological agent of Chagas' disease. Kinetic parameters indicated that GABA is taken up by a single transport system in pathogenic and nonpathogenic forms. Temperature dependence assays showed a profile similar to glutamate transport, but the effect of extracellular cations Na(+) , K(+) , and H(+) on GABA uptake differed, suggesting a different uptake mechanism. In contrast to reports for other amino acid transporters in T. cruzi, GABA uptake was Na(+) dependent and increased with pH, with a maximum activity at pH 8.5. The sensitivity to oligomycin showed that GABA uptake is dependent on ATP synthesis. These data point to a secondary active Na(+) /GABA symporter energized by Na(+) -exporting ATPase. Finally, we show that GABA occurs in the parasite's cytoplasm under normal culture conditions, indicating that it is regularly taken up from the culture medium or synthesized through an still undescribed metabolic pathway. PMID:25851259

  11. High resolution modeling of water and nutrient uptake by plant roots: at a scale from single root to root system

    NASA Astrophysics Data System (ADS)

    Abesha, Betiglu; Vanderborght, Jan; Javaux, Mathieu; Schnepf, Andrea; Vereecken, Harry

    2014-05-01

    The uptake of nutrients by plant roots is a multiscale problem. At the small scale, nutrient fluxes towards single roots lead to strong gradients in nutrient concentrations around single roots. At the scale of the root system and soil profile, nutrient fluxes are generated by water fluxes and variations in nutrient uptake due to spatially varying root density, nutrient concentrations and water contents. In this contribution, we present a numerical simulation model that describes the processes at the scale of a single root and the scale of the entire root system simultaneously. Water flow and nutrient transport in the soil are described by the 3-D Richards and advection-dispersion equations, respectively. Water uptake by a root segment is simulated based on the difference between the soil water potential at the soil root interface and in the xylem tissue. The xylem water potential is derived from solving a set of flow equations that describe flow in the root network (Javaux et al., 2008). Nutrient uptake by a segment is simulated as a function of the nutrient concentration at the soil-root interface using a nonlinear Michaelis-Menten equation. An accurate description of the nutrient concentrations gradients around single roots requires a spatial resolution in the sub mm scale and is therefore not feasible for simulations of the entire root system or soil profile. In order to address this problem, a 1-D axisymmetric model (Barber and Cushman, 1981) was used to describe nutrient transport towards a single root segment. The network of connected cylindrical models was coupled to a 3-D regular grid that was used to solve the flow and transport equations at the root system scale. The coupling was done by matching the fluxes across the interfaces of the voxels of the 3-D grid that contain root segments with the fluxes at the outer boundaries of the cylindrical domains and by matching the sink terms in these voxels with uptake by the root segments. To demonstrate the

  12. System A amino acid transporter SNAT2 shows subtype-specific affinity for betaine and hyperosmotic inducibility in placental trophoblasts.

    PubMed

    Nishimura, Tomohiro; Yagi, Risa; Usuda, Mariko; Oda, Kenji; Yamazaki, Mai; Suda, Sayaka; Takahashi, Yu; Okazaki, Fumiyasu; Sai, Yoshimichi; Higuchi, Kei; Maruyama, Tetsuo; Tomi, Masatoshi; Nakashima, Emi

    2014-05-01

    Betaine uptake is induced by hypertonic stress in a placental trophoblast cell line, and involvement of amino acid transport system A was proposed. Here, we aimed to identify the subtype(s) of system A that mediates hypertonicity-induced betaine uptake. Measurement of [(14)C]betaine uptake by HEK293 cells transiently transfected with human or rat sodium-coupled neutral amino acid transporters (SNATs), SNAT1, SNAT2 and SNAT4 revealed that only human and rat SNAT2 have betaine uptake activity. The Michaelis constants (Km) of betaine uptake by human and rat SNAT2 were estimated to be 5.3 mM and 4.6 mM, respectively. Betaine exclusively inhibited the uptake activity of SNAT2 among the rat system A subtypes. We found that rat SNAT1, SNAT2 and SNAT4 were expressed at the mRNA level under isotonic conditions, while expression of SNAT2 and SNAT4 was induced by hypertonicity in TR-TBT 18d-1 cells. Western blot analyses revealed that SNAT2 expression on plasma membrane of TR-TBT 18d-1 cells was more potently induced by hypertonicity than that in total cell lysate. Immunocytochemistry confirmed the induction of SNAT2 expression in TR-TBT 18d-1 cells exposed to hypertonic conditions and indicated that SNAT2 was localized on the plasma membrane in these cells. Our results indicate that SNAT2 transports betaine, and that tonicity-sensitive SNAT2 expression may be involved in regulation of betaine concentration in placental trophoblasts. PMID:24434061

  13. Fluorous Peptide Nucleic Acids: PNA Analogues with Fluorine in Backbone (γ-CF2-apg-PNA) Enhance Cellular Uptake.

    PubMed

    Ellipilli, Satheesh; Ganesh, Krishna N

    2015-09-18

    Fluorous PNA analogues possessing fluorine as inherent part of aminopropylglycine (apg) backbone (γ-CF2-apg PNA) have been synthesized and evaluated for biophysical and cell penetrating properties. These form duplexes of higher thermal stability with cRNA than cDNA, although destabilized compared to duplexes of standard aeg-PNA. Cellular uptake of the fluorinated γ-CF2-apg PNAs in NIH 3T3 and HeLa cells was 2-3-fold higher compared to that of nonfluorinated apg PNA, with NIH 3T3 cells showing better permeability compared to HeLa cells. The backbone fluorinated PNAs, which are first in this class, when combined with other chemical modifications may have potential for future PNA-based antisense agents. PMID:26322827

  14. Epidermal growth factor inhibits radioiodine uptake but stimulates deoxyribonucleic acid synthesis in newborn rat thyroids grown in nude mice

    SciTech Connect

    Ozawa, S.; Spaulding, S.W. )

    1990-08-01

    We have studied the effect of altering the level of circulating epidermal growth factor (EGF) on the function and growth of newborn rat thyroids transplanted into nude mice. Preliminary studies confirmed that sialoadenectomy reduced circulating EGF levels in nude mice (from 0.17 +/- 0.02 to 0.09 +/- 0.02 ng/ml), and that ip injection of 5 micrograms EGF raised EGF levels (the peak level of 91.7 +/- 3.3 ng/ml was achieved at 30 min, with a subsequent half-life of about 1 h). The radioiodine uptake by newborn rat thyroid transplants in the sialoadenectomized and sham-operated animals correlated inversely with the circulating EGF levels determined when the mice were killed (r = -0.99). Low-dose TSH treatment (0.1 microU/day) generally stimulated the radioiodine uptake, but high-dose TSH groups (100 microU/day) were not significantly different from the control group. The 5-day nuclear (3H)thymidine labeling index was 6.8 +/- 0.5% IN newborn rat thyroid transplants grown in sialoadenectomized animals, 13.1 +/- 0.3% in sham-operated animals, and 16.8 +/- 0.5% in nude mice receiving 5 micrograms EGF ip daily. In general, both low-dose and high-dose TSH promoted DNA synthesis under low EGF conditions but were ineffective in the presence of higher levels of EGF. Adult rat thyroid transplants showed no significant responses. Although sialoadenectomy may alter other factors besides EGF, it appears that changes in the levels of circulating EGF within the physiological range affect the function and growth of newborn rat thyroid transplants. Circulating EGF may play a role in thyroid maturation and may also be involved in the regulation of thyroid function throughout life.

  15. Morphine Induces Redox-Based Changes in Global DNA Methylation and Retrotransposon Transcription by Inhibition of Excitatory Amino Acid Transporter Type 3–Mediated Cysteine Uptake

    PubMed Central

    Trivedi, Malav; Shah, Jayni; Hodgson, Nathaniel; Byun, Hyang-Min

    2014-01-01

    Canonically, opioids influence cells by binding to a G protein–coupled opioid receptor, initiating intracellular signaling cascades, such as protein kinase, phosphatidylinositol 3-kinase, and extracellular receptor kinase pathways. This results in several downstream effects, including decreased levels of the reduced form of glutathione (GSH) and elevated oxidative stress, as well as epigenetic changes, especially in retrotransposons and heterochromatin, although the mechanism and consequences of these actions are unclear. We characterized the acute and long-term influence of morphine on redox and methylation status (including DNA methylation levels) in cultured neuronal SH-SY5Y cells. Acting via μ-opioid receptors, morphine inhibits excitatory amino acid transporter type 3–mediated cysteine uptake via multiple signaling pathways, involving different G proteins and protein kinases in a temporal manner. Decreased cysteine uptake was associated with decreases in both the redox and methylation status of neuronal cells, as defined by the ratios of GSH to oxidized forms of glutathione and S-adenosylmethionine to S-adenosylhomocysteine levels, respectively. Further, morphine induced global DNA methylation changes, including CpG sites in long interspersed nuclear elements (LINE-1) retrotransposons, resulting in increased LINE-1 mRNA. Together, these findings illuminate the mechanism by which morphine, and potentially other opioids, can influence neuronal-cell redox and methylation status including DNA methylation. Since epigenetic changes are implicated in drug addiction and tolerance phenomenon, this study could potentially extrapolate to elucidate a novel mechanism of action for other drugs of abuse. PMID:24569088

  16. Diatoms Si uptake capacity drives carbon export in coastal upwelling systems

    NASA Astrophysics Data System (ADS)

    Abrantes, Fatima; Cermeno, Pedro; Lopes, Cristina; Romero, Oscar; Matos, Lélia; Van Iperen, Jolanda; Rufino, Marta; Magalhães, Vitor

    2016-07-01

    Coastal upwelling systems account for approximately half of global ocean primary production and contribute disproportionately to biologically driven carbon sequestration. Diatoms, silica-precipitating microalgae, constitute the dominant phytoplankton in these productive regions, and their abundance and assemblage composition in the sedimentary record is considered one of the best proxies for primary production. The study of the sedimentary diatom abundance (SDA) and total organic carbon content (TOC) in the five most important coastal upwelling systems of the modern ocean (Iberia-Canary, Benguela, Peru-Humboldt, California, and Somalia-Oman) reveals a global-scale positive relationship between diatom production and organic carbon burial. The analysis of SDA in conjunction with environmental variables of coastal upwelling systems such as upwelling strength, satellite-derived net primary production, and surface water nutrient concentrations shows different relations between SDA and primary production on the regional scale. On the global scale, SDA appears modulated by the capacity of diatoms to take up silicic acid, which ultimately sets an upper limit to global export production in these ocean regions.

  17. Use of ( sup 11 C)aminocyclohexanecarboxylate for the measurement of amino acid uptake and distribution volume in human brain

    SciTech Connect

    Koeppe, R.A.; Mangner, T.; Betz, A.L.; Shulkin, B.L.; Allen, R.; Kollros, P.; Kuhl, D.E.; Agranoff, B.W. )

    1990-09-01

    A quantitative positron emission tomographic (PET) method to measure amino acid blood-brain barrier (BBB) transport rate and tissue distribution volume (DV) has been developed using {sup 11}C-labeled aminocyclohexanecarboxylate (ACHC), a nonmetabolized amino acid analogue. Dynamic PET data were acquired as a series of 15 scans covering a total of 60 min and analyzed by means of a two-compartment, two-parameter model. Functional images were calculated for the amino acid transport rate constants across the BBB and the amino acid DV in the brain. Results show ({sup 11}C)ACHC to have an influx rate constant in gray matter of approximately 0.03-0.04 ml g-1 min-1, indicating a single-pass extraction fraction of approximately 5-7%. The intersubject coefficient of variation was approximately 15% while intrasubject variability of repeat scans was only slightly greater than 5%. Studies were performed in 15 young normal volunteer control subjects, 5 elderly controls, 7 patients with probable Alzheimer's disease, and one patient with phenylketonuria. Results indicate that ({sup 11}C)-ACHC will serve as the basis of a method for measuring amino acid transport rate and DV in the normal and pathological human brain.

  18. High-Speed Microdialysis-Capillary Electrophoresis Assays for Measuring Branched Chain Amino Acid Uptake in 3T3-L1 cells.

    PubMed

    Harstad, Rachel K; Bowser, Michael T

    2016-08-16

    We have developed a high-throughput microdialysis-capillary electrophoresis (MD-CE) assay for monitoring branched chain amino acid (BCAA) uptake/release dynamics in 3T3-L1 cells. BCAAs (i.e., isoleucine, leucine, and valine) and their downstream metabolites (i.e., alanine, glutamine, and glutamate) are important indicators of adipocyte lipogenesis. To perform an analysis, amino acids were sampled using microdialysis, fluorescently labeled in an online reaction, separated using CE, and detected using laser-induced fluorescence (LIF) in a sheath flow cuvette. Separation conditions were optimized for the resolution of the BCAAs isoleucine, leucine, and valine, as well as 13 other amino acids, including ornithine, alanine, glutamine, and glutamate. CE separations were performed in <30 s, and the temporal resolution of the online MD-CE assay was <60 s. Limits of detection (LOD) were 400, 200, and 100 nM for isoleucine, leucine, and valine, respectively. MD-CE dramatically improved throughput in comparison to traditional offline CE methods, allowing 8 replicates of 15 samples (i.e., 120 analyses) to be assayed in <120 min. The MD-CE assay was used to assess the metabolism dynamics of 3T3-L1 cells over time, confirming the utility of the assay. PMID:27398773

  19. Lysophosphatidic Acid signaling in the nervous system.

    PubMed

    Yung, Yun C; Stoddard, Nicole C; Mirendil, Hope; Chun, Jerold

    2015-02-18

    The brain is composed of many lipids with varied forms that serve not only as structural components but also as essential signaling molecules. Lysophosphatidic acid (LPA) is an important bioactive lipid species that is part of the lysophospholipid (LP) family. LPA is primarily derived from membrane phospholipids and signals through six cognate G protein-coupled receptors (GPCRs), LPA1-6. These receptors are expressed on most cell types within central and peripheral nervous tissues and have been functionally linked to many neural processes and pathways. This Review covers a current understanding of LPA signaling in the nervous system, with particular focus on the relevance of LPA to both physiological and diseased states. PMID:25695267

  20. Retinoic Acid in the Immune System

    PubMed Central

    Pino-Lagos, Karina; Benson, Micah J.; Noelle, Randolph J.

    2013-01-01

    On occasion, emerging scientific fields intersect and great discoveries result. In the last decade, the discovery of regulatory T cells (Treg) in immunity has revolutionized our understanding of how the immune system is controlled. Intersecting the rapidly emerging field of Treg function, has been the discovery that retinoic acid (RA) controls both the homing and differentiation of Treg. Instantly, the wealth and breadth of knowledge of the molecular basis for RA action, its receptors, and how it controls cellular differentiation can and will be exploited to understand its profound effects on Treg. Historically, vitamin A deprivation and repletion and RA agonists have been shown to profoundly affect immunity. Now these findings can be interpreted in light of the revelations that RA controls leukocyte homing and Treg function. PMID:19076350

  1. Hydroxybenzoic acid isomers and the cardiovascular system

    PubMed Central

    2014-01-01

    Today we are beginning to understand how phytochemicals can influence metabolism, cellular signaling and gene expression. The hydroxybenzoic acids are related to salicylic acid and salicin, the first compounds isolated that have a pharmacological activity. In this review we examine how a number of hydroxyphenolics have the potential to ameliorate cardiovascular problems related to aging such as hypertension, atherosclerosis and dyslipidemia. The compounds focused upon include 2,3-dihydroxybenzoic acid (Pyrocatechuic acid), 2,5-dihydroxybenzoic acid (Gentisic acid), 3,4-dihydroxybenzoic acid (Protocatechuic acid), 3,5-dihydroxybenzoic acid (α-Resorcylic acid) and 3-monohydroxybenzoic acid. The latter two compounds activate the hydroxycarboxylic acid receptors with a consequence there is a reduction in adipocyte lipolysis with potential improvements of blood lipid profiles. Several of the other compounds can activate the Nrf2 signaling pathway that increases the expression of antioxidant enzymes, thereby decreasing oxidative stress and associated problems such as endothelial dysfunction that leads to hypertension as well as decreasing generalized inflammation that can lead to problems such as atherosclerosis. It has been known for many years that increased consumption of fruits and vegetables promotes health. We are beginning to understand how specific phytochemicals are responsible for such therapeutic effects. Hippocrates’ dictum of ‘Let food be your medicine and medicine your food’ can now be experimentally tested and the results of such experiments will enhance the ability of nutritionists to devise specific health-promoting diets. PMID:24943896

  2. Analysis of the high-affinity iron uptake system at the Chlamydomonas reinhardtii plasma membrane.

    PubMed

    Terzulli, Alaina; Kosman, Daniel J

    2010-05-01

    Multicopper ferroxidases play a vital role in iron metabolism in bacteria, fungi, algae, and mammals. Saccharomyces cerevisiae utilizes a channeling mechanism to couple the ferroxidase activity of Fet3p to Fe(3+) transport into the cell by Ftr1p. In contrast, the mechanisms by which mammals couple the ferroxidase reaction to iron trafficking is unclear. The human ferroxidases ceruloplasmin and hephaestin are twice the size of Fet3p and interact with proteins that are not expressed in fungi. Chlamydomonas FOX1 is a homolog of the human ferroxidases but likely supports iron uptake in a manner similar to that of yeast, since Chlamydomonas reinhardtii expresses a ferric iron permease homolog, FTR1. The results presented support this hypothesis. We show that FOX1 is trafficked to the plasma membrane and is oriented with its multicopper oxidase/ferroxidase domain in the exocytoplasmic space. Our analysis of FTR1 indicates its topology is similar to that of S. cerevisiae Ftr1p, with a potential exocytoplasmic iron channeling motif and two potential iron permeation motifs in membrane-spanning regions. We demonstrate that high-affinity iron uptake is dependent on FOX1 and the copper status of the cell. Kinetic inhibition of high-affinity iron uptake by a ferric iron chelator does not reflect the strength of the chelator, supporting a ferric iron channeling mechanism for high-affinity iron uptake in Chlamydomonas. Last, recombinant FOX1 (rFOX1) has been isolated in a partially holo form that exhibits the UV-visible absorbance spectrum of a multicopper oxidase and the catalytic activity of a ferroxidase. PMID:20348389

  3. Uptake Mechanism for Iodine Species to Black Carbon

    SciTech Connect

    Choung, Sungwook; Um, Wooyong; Kim, Min Kyung; Kim, Min-Gyu

    2013-08-13

    Natural organic matter (NOM) plays an important role in determining the fate and transport of iodine species such as iodide (I-) and iodate (IO3-) in groundwater system. Although NOM exists as diverse forms in environments, prior iodine studies have mainly focused on uptake processes of iodide and iodate to humic materials. This study was conducted to determine the iodide and iodate uptake potential for a particulate NOM (i.e., black carbon [BC]). A laboratory-produced BC and commercial humic acid were used for batch experiments to compare their iodine uptake properties. The BC exhibited >100 times greater uptake capability for iodide than iodate at low pH~3, while iodide uptake was negligible for the humic acid. The uptake properties of both solids strongly depend on the initial iodine aqueous concentrations. After uptake reaction of iodide to the BC, X-ray Absorption Fine Structure spectroscopy results indicated that the iodide was converted to electrophilic species, and iodine was covalently bound to carbon atom in polycyclic aromatic hydrocarbons present in the BC. The computed distribution coefficients (i.e., Kd values) suggest that the BC materials retard significantly the transport of iodide at low pH in environmental systems containing even a small amount of BC.

  4. Simultaneous monitoring of electrical capacitance and water uptake activity of plant root system

    NASA Astrophysics Data System (ADS)

    Cseresnyés, Imre; Takács, Tünde; Füzy, Anna; Rajkai, Kálmán

    2014-10-01

    Pot experiments were designed to test the applicability of root electrical capacitance measurement for in situ monitoring of root water uptake activity by growing cucumber and bean cultivars in a growth chamber. Half of the plants were inoculated with Funneliformis mosseae arbuscular mycorrhizal fungi, while the other half served as non-infected controls. Root electrical capacitance and daily transpiration were monitored during the whole plant ontogeny. Phenology-dependent changes of daily transpiration (related to root water uptake) and root electrical capacitance proved to be similar as they showed upward trends from seedling emergence to the beginning of flowering stage, and thereafter decreased continuously during fruit setting. A few days after arbuscular mycorrhizal fungi-colonization, daily transpiration and root electrical capacitance of infected plants became significantly higher than those of non-infected counterparts, and the relative increment of the measured parameters was greater for the more highly mycorrhizal-dependent bean cultivar compared to that of cucumber. Arbuscular mycorrhizal fungi colonization caused 29 and 69% relative increment in shoot dry mass for cucumbers and beans, respectively. Mycorrhization resulted in 37% increase in root dry mass for beans, but no significant difference was observed for cucumbers. Results indicate the potential of root electrical capacitance measurements for monitoring the changes and differences of root water uptake rate.

  5. The contribution of SNAT1 to system A amino acid transporter activity in human placental trophoblast

    SciTech Connect

    Desforges, M.; Greenwood, S.L.; Glazier, J.D.; Westwood, M.; Sibley, C.P.

    2010-07-16

    Research highlights: {yields} mRNA levels for SNAT1 are higher than other system A subtype mRNAs in primary human cytotrophoblast. {yields} SNAT1 knockdown in cytotrophoblast cells significantly reduces system A activity. {yields} SNAT1 is a key contributor to system A-mediated amino acid transport in human placenta. -- Abstract: System A-mediated amino acid transport across the placenta is important for the supply of neutral amino acids needed for fetal growth. All three system A subtypes (SNAT1, 2, and 4) are expressed in human placental trophoblast suggesting there is an important biological role for each. Placental system A activity increases as pregnancy progresses, coinciding with increased fetal nutrient demands. We have previously shown SNAT4-mediated system A activity is higher in first trimester than at term, suggesting that SNAT1 and/or SNAT2 are responsible for the increased system A activity later in gestation. However, the relative contribution of each subtype to transporter activity in trophoblast at term has yet to be evaluated. The purpose of this study was to identify the predominant subtype of system A in cytotrophoblast cells isolated from term placenta, maintained in culture for 66 h, by: (1) measuring mRNA expression of the three subtypes and determining the Michaelis-Menten constants for uptake of the system A-specific substrate, {sup 14}C-MeAIB, (2) investigating the contribution of SNAT1 to total system A activity using siRNA. Results: mRNA expression was highest for the SNAT1 subtype of system A. Kinetic analysis of {sup 14}C-MeAIB uptake revealed two distinct transport systems; system 1: K{sub m} = 0.38 {+-} 0.12 mM, V{sub max} = 27.8 {+-} 9.0 pmol/mg protein/20 min, which resembles that reported for SNAT1 and SNAT2 in other cell types, and system 2: K{sub m} = 45.4 {+-} 25.0 mM, V{sub max} = 1190 {+-} 291 pmol/mg protein/20 min, which potentially represents SNAT4. Successful knockdown of SNAT1 mRNA using target-specific si

  6. Regional and systemic oxygen delivery/uptake relations and lactate flux in hyperdynamic, endotoxin-treated dogs.

    PubMed

    Curtis, S E; Cain, S M

    1992-02-01

    Pathologic oxygen supply dependency (PO2SD) may be etiologic in multisystem organ failure (MSOF) and has been related to mortality in sepsis. Although elevated lactate levels are generally assumed to be a marker of anaerobiosis in these patients, endotoxin may increase serum lactate by inactivation of pyruvate dehydrogenase (PDH), unrelated to tissue PO2. We hypothesized that regional lactate flux may correlate poorly with local oxygen delivery in sepsis. This study examined both the whole-body (WB) and regional (isolated hind limb L and gut G) responses to endotoxin infusion in terms of oxygen delivery, oxygen uptake, and lactate flux in 12 pentobarbital-anesthetized dogs. To separate hypoxia-induced lactate production from that related to inactivation of PDH by endotoxin, half the dogs received dichloroacetate (DCA), a PDH activator. After endotoxin and volume resuscitation, each animal had low systemic vascular resistance with normal to high cardiac output. Despite adequate oxygen delivery to WB, L, and G, arterial lactate levels rose significantly. A 30-min hypoxic challenge (12% FIO2) did not increase lactate levels but did increase WB O2 uptake. DCA normalized lactate levels without influencing oxygen delivery and uptake relations. These data show that lactate levels in endotoxic states may be a poor marker of tissue hypoxia and may be more related to PDH activity. PMID:1736740

  7. Dendritic polymer imaging systems for the evaluation of conjugate uptake and cleavage

    NASA Astrophysics Data System (ADS)

    Krüger, Harald R.; Nagel, Gregor; Wedepohl, Stefanie; Calderón, Marcelo

    2015-02-01

    Fluorescent turn-on probes combined with polymers have a broad range of applications, e.g. for intracellular sensing of ions, small molecules, or DNA. In the field of polymer therapeutics, these probes can be applied to extend the in vitro characterization of novel conjugates beyond cytotoxicity and cellular uptake studies. This is particularly true in cases in which polymer conjugates contain drugs attached by cleavable linkers. Better information on the intracellular linker cleavage and drug release would allow a faster evaluation and optimization of novel polymer therapeutic concepts. We therefore developed a fluorescent turn-on probe that enables direct monitoring of pH-mediated cleavage processes over time. This is achieved by exploiting the fluorescence resonance energy transfer (FRET) between two dyes that have been coupled to a dendritic polymer. We demonstrate the use of this probe to evaluate polymer uptake and intracellular release of cargo in a cell based microplate assay that is suitable for high throughput screening.Fluorescent turn-on probes combined with polymers have a broad range of applications, e.g. for intracellular sensing of ions, small molecules, or DNA. In the field of polymer therapeutics, these probes can be applied to extend the in vitro characterization of novel conjugates beyond cytotoxicity and cellular uptake studies. This is particularly true in cases in which polymer conjugates contain drugs attached by cleavable linkers. Better information on the intracellular linker cleavage and drug release would allow a faster evaluation and optimization of novel polymer therapeutic concepts. We therefore developed a fluorescent turn-on probe that enables direct monitoring of pH-mediated cleavage processes over time. This is achieved by exploiting the fluorescence resonance energy transfer (FRET) between two dyes that have been coupled to a dendritic polymer. We demonstrate the use of this probe to evaluate polymer uptake and intracellular

  8. Lack of Control in Inorganic Phosphate Uptake by Catharanthus roseus (L.) G. Don Cells (Cytoplasmic Inorganic Phosphate Homeostasis Depends on the Tonoplast Inorganic Phosphate Transport System?).

    PubMed Central

    Sakano, K.; Yazaki, Y.; Okihara, K.; Mimura, T.; Kiyota, S.

    1995-01-01

    Inorganic phosphate (Pi) uptake by Catharanthus roseus (L.) G. Don cells was studied in relation to its apparent uncontrolled uptake using 31P-nuclear magnetic resonance spectroscopy. Kinetics of Pi uptake by the cells indicated that apparent Km and Vm were about 7 [mu]M and 20 [mu]mol g-1 fresh weight h-1, respectively. Pi uptake in Murashige-Skoog medium under different Pi concentrations and different initial cell densities followed basically the same kinetics. When supplied with abundant Pi, cells absorbed Pi at a constant rate (Vm) for the first hours and accumulated it in the vacuole. As the endogenous pool expanded, the rate of Pi uptake gradually decreased to nil. Maximum Pi accumulation was 100 to 120 [mu]mol g-1 fresh weight if cell swelling during Pi uptake (about 2-fold in cell volume) was not considered. Results indicated that (a) the rate of Pi uptake by Catharanthus cells was independent of initial cell density and was constant over a wide range of Pi concentrations (2 mM to about 10 [mu]M) unless the cells were preloaded with excess Pi, and (b) there was no apparent feedback control over the Pi uptake process in the plasma membrane to avoid Pi toxicity. The importance of the tonoplast Pi transport system in cytoplasmic Pi homeostasis is discussed. PMID:12228474

  9. Abscisic acid ameliorates the systemic sclerosis fibroblast phenotype in vitro

    SciTech Connect

    Bruzzone, Santina; Battaglia, Florinda; Mannino, Elena; Parodi, Alessia; Fruscione, Floriana; Basile, Giovanna; Salis, Annalisa; Sturla, Laura; Negrini, Simone; Kalli, Francesca; Stringara, Silvia; Filaci, Gilberto; and others

    2012-05-25

    Highlights: Black-Right-Pointing-Pointer ABA is an endogenous hormone in humans, regulating different cell responses. Black-Right-Pointing-Pointer ABA reverts some of the functions altered in SSc fibroblasts to a normal phenotype. Black-Right-Pointing-Pointer UV-B irradiation increases ABA content in SSc cultures. Black-Right-Pointing-Pointer SSc fibroblasts could benefit from exposure to ABA and/or to UV-B. -- Abstract: The phytohormone abscisic acid (ABA) has been recently identified as an endogenous hormone in humans, regulating different cell functions, including inflammatory processes, insulin release and glucose uptake. Systemic sclerosis (SSc) is a chronic inflammatory disease resulting in fibrosis of skin and internal organs. In this study, we investigated the effect of exogenous ABA on fibroblasts obtained from healthy subjects and from SSc patients. Migration of control fibroblasts induced by ABA was comparable to that induced by transforming growth factor-{beta} (TGF-{beta}). Conversely, migration toward ABA, but not toward TGF-{beta}, was impaired in SSc fibroblasts. In addition, ABA increased cell proliferation in fibroblasts from SSc patients, but not from healthy subjects. Most importantly, presence of ABA significantly decreased collagen deposition by SSc fibroblasts, at the same time increasing matrix metalloproteinase-1 activity and decreasing the expression level of tissue inhibitor of metalloproteinase (TIMP-1). Thus, exogenously added ABA appeared to revert some of the functions altered in SSc fibroblasts to a normal phenotype. Interestingly, ABA levels in plasma from SSc patients were found to be significantly lower than in healthy subjects. UV-B irradiation induced an almost 3-fold increase in ABA content in SSc cultures. Altogether, these results suggest that the fibrotic skin lesions in SSc patients could benefit from exposure to high(er) ABA levels.

  10. Role of SbmA in the uptake of peptide nucleic acid (PNA)-peptide conjugates in E. coli.

    PubMed

    Ghosal, Anubrata; Vitali, Ally; Stach, James E M; Nielsen, Peter E

    2013-02-15

    Antisense PNA oligomers targeting essential genes (acpP or ftsZ) and conjugated to the delivery peptide L((KFF)(3)K) show complete growth inhibition of wild type E. coli strain (MG1655) with submicromolar MIC. In this study we show that resistant mutants generated against such PNA-peptide conjugates had disruptions in the region of sbmA, a gene encoding an inner membrane peptide transporter. The wild type sensitivity to the PNA conjugates was re-established in the resistance mutants by complementation with sbmA. Furthermore, deletion of sbmA in E. coli AS19, a strain that is sensitive to unmodified PNA, resulted in resistance to PNA. Finally, PNA conjugated with the corresponding non-biological H-D((KFF)(3)K) peptide retained antibacterial activity in sbmA deletion strains, whereas the same conjugate with a protease-sensitive linker did not. These results clearly identify SbmA as a carrier of naked PNA over the inner bacterial membrane and thereby infer that the peptide is transporting the PNA conjugates over the outer membrane. Strains lacking SbmA were used to screen novel peptide-PNA carriers that were SbmA-independent. Four such PNA-peptide conjugates, H-D((KFF)(3)K), H-(RFR)(4)-Ahx-βAla, H-(R-Ahx-R)(4)-Ahx-βAla, and H-(R-Ahx)(6)-βAla, were identified that utilize an alternative uptake mechanism but retain their antimicrobial potency. In addition SbmA is the first protein identified to recognize PNA. PMID:23138594

  11. 21 CFR 862.1295 - Folic acid test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Folic acid test system. 862.1295 Section 862.1295 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862.1295 Folic acid test system. (a)...

  12. 21 CFR 862.1450 - Lactic acid test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Lactic acid test system. 862.1450 Section 862.1450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862.1450 Lactic acid test system....

  13. 21 CFR 862.1775 - Uric acid test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Uric acid test system. 862.1775 Section 862.1775 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862.1775 Uric acid test system. (a) Identification....

  14. 21 CFR 862.1450 - Lactic acid test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Lactic acid test system. 862.1450 Section 862.1450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862.1450 Lactic acid test system....

  15. Preparation of poly(β-L-malic acid)-based charge-conversional nanoconjugates for tumor-specific uptake and cellular delivery

    PubMed Central

    Zhou, Qing; Yang, Tiehong; Qiao, Youbei; Guo, Songyan; Zhu, Lin; Wu, Hong

    2015-01-01

    In this study, a multifunctional poly(β-L-malic acid)-based nanoconjugate with a pH-dependent charge conversional characteristic was developed for tumor-specific drug delivery. The short branched polyethylenimine-modified poly(β-L-malic acid) (PEPM) was first synthesized. Then, the fragment HAb18 F(ab′)2 and 2,3-dimethylmaleic anhydride were covalently attached to the PEPM to form the nanoconjugate, HDPEPM. In this nanoconjugate, the 2,3-dimethylmaleic anhydride, the shielding group, could shield the positive charge of the conjugate at pH 7.4, while it was selectively hydrolyzed in the tumor extracellular space (pH 6.8) to expose the previously-shielded positive charge. To study the anticancer activity, the anticancer drug, doxorubicin, was covalently attached to the nanoconjugate. The doxorubicin-loaded HDPEPM nanoconjugate was able to efficiently undergo a quick charge conversion from −11.62 mV to 9.04 mV in response to the tumor extracellular pH. The electrostatic interaction between the positively charged HDPEPM nanoconjugates and the negatively charged cell membrane significantly enhanced their cellular uptake, resulting in the enhanced anticancer activity. Also, the tumor targetability of the nanoconjugates could be further improved via the fragment HAb18 F(ab′)2 ligand–receptor-mediated tumor cell-specific endocytosis. PMID:25792828

  16. Genetic diversity of inorganic carbon uptake systems causes variation in CO2 response of the cyanobacterium Microcystis

    PubMed Central

    Sandrini, Giovanni; Matthijs, Hans C P; Verspagen, Jolanda M H; Muyzer, Gerard; Huisman, Jef

    2014-01-01

    Rising CO2 levels may act as an important selective factor on the CO2-concentrating mechanism (CCM) of cyanobacteria. We investigated genetic diversity in the CCM of Microcystis aeruginosa, a species producing harmful cyanobacterial blooms in many lakes worldwide. All 20 investigated Microcystis strains contained complete genes for two CO2 uptake systems, the ATP-dependent bicarbonate uptake system BCT1 and several carbonic anhydrases (CAs). However, 12 strains lacked either the high-flux bicarbonate transporter BicA or the high-affinity bicarbonate transporter SbtA. Both genes, bicA and sbtA, were located on the same operon, and the expression of this operon is most likely regulated by an additional LysR-type transcriptional regulator (CcmR2). Strains with only a small bicA fragment clustered together in the phylogenetic tree of sbtAB, and the bicA fragments were similar in strains isolated from different continents. This indicates that a common ancestor may first have lost most of its bicA gene and subsequently spread over the world. Growth experiments showed that strains with sbtA performed better at low inorganic carbon (Ci) conditions, whereas strains with bicA performed better at high Ci conditions. This offers an alternative explanation of previous competition experiments, as our results reveal that the competition at low CO2 levels was won by a specialist with only sbtA, whereas a generalist with both bicA and sbtA won at high CO2 levels. Hence, genetic and phenotypic variation in Ci uptake systems provide Microcystis with the potential for microevolutionary adaptation to changing CO2 conditions, with a selective advantage for bicA-containing strains in a high-CO2 world. PMID:24132080

  17. Cationic Amino Acid Uptake Constitutes a Metabolic Regulation Mechanism and Occurs in the Flagellar Pocket of Trypanosoma cruzi

    PubMed Central

    Bouvier, León A.; Cámara, María de los Milagros; Montserrat, Javier; Pereira, Claudio A.

    2012-01-01

    Trypanosomatids' amino acid permeases are key proteins in parasite metabolism since they participate in the adaptation of parasites to different environments. Here, we report that TcAAP3, a member of a Trypanosoma cruzi multigene family of permeases, is a bona fide arginine transporter. Most higher eukaryotic cells incorporate cationic amino acids through a single transporter. In contrast, T. cruzi can recognize and transport cationic amino acids by mono-specific permeases since a 100-fold molar excess of lysine could not affect the arginine transport in parasites that over-express the arginine permease (TcAAP3 epimastigotes). In order to test if the permease activity regulates downstream processes of the arginine metabolism, the expression of the single T. cruzi enzyme that uses arginine as substrate, arginine kinase, was evaluated in TcAAP3 epimastigotes. In this parasite model, intracellular arginine concentration increases 4-folds and ATP level remains constant until cultures reach the stationary phase of growth, with decreases of about 6-folds in respect to the controls. Interestingly, Western Blot analysis demonstrated that arginine kinase is significantly down-regulated during the stationary phase of growth in TcAAP3 epimastigotes. This decrease could represent a compensatory mechanism for the increase in ATP consumption as a consequence of the displacement of the reaction equilibrium of arginine kinase, when the intracellular arginine concentration augments and the glucose from the medium is exhausted. Using immunofluorescence techniques we also determined that TcAAP3 and the specific lysine transporter TcAAP7 co-localize in a specialized region of the plasma membrane named flagellar pocket, staining a single locus close to the flagellar pocket collar. Taken together these data suggest that arginine transport is closely related to arginine metabolism and cell energy balance. The clinical relevance of studying trypanosomatids' permeases relies on the

  18. Regulations of essential amino acids and proteomics of bacterial endophytes Sphingomonas sp. Lk11 during cadmium uptake.

    PubMed

    Khan, Abdul Latif; Ullah, Ihsan; Hussain, Javid; Kang, Sang-Mo; Al-Harrasi, Ahmed; Al-Rawahi, Ahmed; Lee, In-Jung

    2016-07-01

    Endophytic bacteria have been recently known for their potential to bioaccumulate metal from contaminated mediums. However, little is known about the physiological responses of phytohormone producing (gibberellins and auxins) endophytes during metal stressed environment. Endophytic bacteria Sphingomonas sp. LK11 was assessed for metals bioaccumulation and its physiological responses towards metal stress. The endophyte was grown in cadmium (Cd), zinc (Zn), aluminum (Al), manganese (Mn), and copper (Cu) contaminated mediums. The results revealed significantly higher endophytic growth potentials in Cd, Cu and Zn contaminations; however, the bio-accumulation rate of Cd was more prolific as compared to Zn and Cu. Interestingly, the SDS-PAGE profile showed increased expressions of proteins in Zn and Cu than in Cd. A similar attenuate response of amino acids was also observed for Cd than in case of Zn and Cu. Only asparagine, glutamate and proline showed significant impact in Cd while Cu and Zn had significantly higher responses of almost all amino acids. Detailed protein profile showed the activation of chaperone, antioxidative and detoxification proteins. Increased regulations of oxidoreductases, superoxide dismutase, thioredoxin, malate dehydrogenase, 2-oxoisovalerate dehydrogenase, 2-oxoisovalerate dehydrogenase, and dihydrolipoyl dehydrogenase were observed. The cellular defense-related protein responses were potent against Cd stress. The results conclude that Sphingomonas sp. LK11 reprogram its amino acids and proteomic expressions and maintain a steady growth during Cd stress. Using such phytohromones producing endophytic bacterium can be ideal approach to increase the phytoextraction potential of metal remediating plants. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 887-896, 2016. PMID:25533023

  19. Amino acid isotopic analysis in agricultural systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A relatively new approach to stable isotopic analysis—referred to as compound-specific isotopic analysis (CSIA)—has emerged, centering on the measurement of 15N:14N ratios in amino acids (glutamic acid and phenylalanine). CSIA has recently been used to generate trophic position estimates among anima...

  20. Androgen uptake in the female reproductive system of a nonhuman primate

    SciTech Connect

    Weaker, F.J.; Sheridan, P.J.

    1981-07-15

    The nuclear uptake and retention of /sup 3/H-dehydrotestosterone (/sup 3/H-DHT) were studied in the reproductive organs of the female rhesus monkey by autoradiography. Ovariectomized and adrenalectomized adult female monkeys were injected with 1 microgram of /sup 3/H-DHT (107 Ci/mmole) and were exsanguinated 1 hour later. The uterus, cervix, vagina, and fimbriae of the fallopian tubes were removed and processed for autoradiography. Localization of the androgen was observed in the nuclei of fibroblasts, but not in the nuclei of smooth muscle and tissues of the blood vessels, of all four organs. The uptake of androgen by the epithelium varied for each organ. The simple columnar epithelium of the fallopian tube demonstrated nuclear labeling, but the epithelium of the uterus did not. The cells of the germinative layer of the stratified squamous epithelium of both the cervix and vagina exhibited nuclear concentration of label; however, the simple columnar epithelium of the cervix contiguous with the uterus was free of label. The results suggest that androgens may have a physiologic role in the female reproductive organs, and that the therapeutic effect of drugs such as danazol may be mediated via an androgen receptor.

  1. Effects of simulated acid rain on nutrient uptake in annual rye grass grown in surface mine soil

    SciTech Connect

    Martin, A.; Aharrah, E.C.

    1984-12-01

    This study was performed to determine the effects of simulated acid rain on the growth, along with the Fe, Mn, and Al concentrations found in a common revegetation species, annual rye grass, Lolium multiflorum Lam. Annual rye grass seeds were planted in two sets of pots. One set was filled with potting soil and the other with surface mine soil. Both sets were divided into three groups, each receiving applications of simulated acid rain of either pH 5.7, 4.0, or 3.0. After five weeks of growth, grasses from each pot were harvested. Dry weight, root length, leaf blade length, plant number, and concentrations of Al, Mn, and Fe were determined for each sample. There was an observable decrease in plant growth and number as the pH decreased. Seed germination ranged from six to ten days longer in pots receiving waterings of pH 3.0 compared to those with a pH of 5.7. The concentrations of Al and Fe increased in the plants between treatments 4.0 and 3.0. Mn concentrations were unaffected by pH. Plants grown in mine soil produced less biomass and showed an increase in Al, Mn, and Fe content as compared to those plants grown in potting soil.

  2. Citric acid modifies surface properties of commercial CeO2 nanoparticles reducing their toxicity and cerium uptake in radish (Raphanus sativus) seedlings.

    PubMed

    Trujillo-Reyes, J; Vilchis-Nestor, A R; Majumdar, S; Peralta-Videa, J R; Gardea-Torresdey, J L

    2013-12-15

    Little is known about the mobility, reactivity, and toxicity to plants of coated engineered nanoparticles (ENPs). Surface modification may change the interaction of ENPs with living organisms. This report describes surface changes in commercial CeO2 NPs coated with citric acid (CA) at molar ratios of 1:2, 1:3, 1:7, and 1:10 CeO2:CA, and their effects on radish (Raphanus sativus) seed germination, cerium and nutrients uptake. All CeO2 NPs and their absorption by radish plants were characterized by TEM, DLS, and ICP-OES. Radish seeds were germinated in pristine and CA coated CeO2 NPs suspensions at 50mg/L, 100mg/L, and 200mg/L. Deionized water and CA at 100mg/L were used as controls. Results showed ζ potential values of 21.6 mV and -56 mV for the pristine and CA coated CeO2 NPs, respectively. TEM images showed denser layers surrounding the CeO2 NPs at higher CA concentrations, as well as better distribution and smaller particle sizes. None of the treatments affected seed germination. However, at 200mg/L the CA coated NPs at 1:7 ratio produced significantly (p ≤ 0.05) more root biomass, increased water content and reduced by 94% the Ce uptake, compared to bare NPs. This suggests that CA coating decrease CeO2 NPs toxicity to plants. PMID:24231324

  3. Adjunctive β2-agonist treatment reduces glycogen independently of receptor-mediated acid α-glucosidase uptake in the limb muscles of mice with Pompe disease.

    PubMed

    Farah, Benjamin L; Madden, Lauran; Li, Songtao; Nance, Sierra; Bird, Andrew; Bursac, Nenad; Yen, Paul M; Young, Sarah P; Koeberl, Dwight D

    2014-05-01

    Enzyme or gene replacement therapy with acid α-glucosidase (GAA) has achieved only partial efficacy in Pompe disease. We evaluated the effect of adjunctive clenbuterol treatment on cation-independent mannose-6-phosphate receptor (CI-MPR)-mediated uptake and intracellular trafficking of GAA during muscle-specific GAA expression with an adeno-associated virus (AAV) vector in GAA-knockout (KO) mice. Clenbuterol, which increases expression of CI-MPR in muscle, was administered with the AAV vector. This combination therapy increased latency during rotarod and wirehang testing at 12 wk, in comparison with vector alone. The mean urinary glucose tetrasaccharide (Glc4), a urinary biomarker, was lower in GAA-KO mice following combination therapy, compared with vector alone. Similarly, glycogen content was lower in cardiac and skeletal muscle following 12 wk of combination therapy in heart, quadriceps, diaphragm, and soleus, compared with vector alone. These data suggested that clenbuterol treatment enhanced trafficking of GAA to lysosomes, given that GAA was expressed within myofibers. The integral role of CI-MPR was demonstrated by the lack of effectiveness from clenbuterol in GAA-KO mice that lacked CI-MPR in muscle, where it failed to reverse the high glycogen content of the heart and diaphragm or impaired wirehang performance. However, the glycogen content of skeletal muscle was reduced by the addition of clenbuterol in the absence of CI-MPR, as was lysosomal vacuolation, which correlated with increased AKT signaling. In summary, β2-agonist treatment enhanced CI-MPR-mediated uptake and trafficking of GAA in mice with Pompe disease, and a similarly enhanced benefit might be expected in other lysosomal storage disorders. PMID:24448824

  4. Benzene Uptake and Glutathione S-transferase T1 Status as Determinants of S-Phenylmercapturic Acid in Cigarette Smokers in the Multiethnic Cohort

    PubMed Central

    Haiman, Christopher A.; Patel, Yesha M.; Stram, Daniel O.; Carmella, Steven G.; Chen, Menglan; Wilkens, Lynne R.; Le Marchand, Loic; Hecht, Stephen S.

    2016-01-01

    Research from the Multiethnic Cohort (MEC) demonstrated that, for the same quantity of cigarette smoking, African Americans and Native Hawaiians have a higher lung cancer risk than Whites, while Latinos and Japanese Americans are less susceptible. We collected urine samples from 2,239 cigarette smokers from five different ethnic groups in the MEC and analyzed each sample for S-phenylmercapturic acid (SPMA), a specific biomarker of benzene uptake. African Americans had significantly higher (geometric mean [SE] 3.69 [0.2], p<0.005) SPMA/ml urine than Whites (2.67 [0.13]) while Japanese Americans had significantly lower levels than Whites (1.65 [0.07], p<0.005). SPMA levels in Native Hawaiians and Latinos were not significantly different from those of Whites. We also conducted a genome-wide association study in search of genetic risk factors related to benzene exposure. The glutathione S-transferase T1 (GSTT1) deletion explained between 14.2–31.6% (p = 5.4x10-157) and the GSTM1 deletion explained between 0.2%-2.4% of the variance (p = 1.1x10-9) of SPMA levels in these populations. Ethnic differences in levels of SPMA remained strong even after controlling for the effects of these two deletions. These results demonstrate the powerful effect of GSTT1 status on SPMA levels in urine and show that uptake of benzene in African American, White, and Japanese American cigarette smokers is consistent with their lung cancer risk in the MEC. While benzene is not generally considered a cause of lung cancer, its metabolite SPMA could be a biomarker for other volatile lung carcinogens in cigarette smoke. PMID:26959369

  5. Benzene Uptake and Glutathione S-transferase T1 Status as Determinants of S-Phenylmercapturic Acid in Cigarette Smokers in the Multiethnic Cohort.

    PubMed

    Haiman, Christopher A; Patel, Yesha M; Stram, Daniel O; Carmella, Steven G; Chen, Menglan; Wilkens, Lynne R; Le Marchand, Loic; Hecht, Stephen S

    2016-01-01

    Research from the Multiethnic Cohort (MEC) demonstrated that, for the same quantity of cigarette smoking, African Americans and Native Hawaiians have a higher lung cancer risk than Whites, while Latinos and Japanese Americans are less susceptible. We collected urine samples from 2,239 cigarette smokers from five different ethnic groups in the MEC and analyzed each sample for S-phenylmercapturic acid (SPMA), a specific biomarker of benzene uptake. African Americans had significantly higher (geometric mean [SE] 3.69 [0.2], p<0.005) SPMA/ml urine than Whites (2.67 [0.13]) while Japanese Americans had significantly lower levels than Whites (1.65 [0.07], p<0.005). SPMA levels in Native Hawaiians and Latinos were not significantly different from those of Whites. We also conducted a genome-wide association study in search of genetic risk factors related to benzene exposure. The glutathione S-transferase T1 (GSTT1) deletion explained between 14.2-31.6% (p = 5.4x10-157) and the GSTM1 deletion explained between 0.2%-2.4% of the variance (p = 1.1x10-9) of SPMA levels in these populations. Ethnic differences in levels of SPMA remained strong even after controlling for the effects of these two deletions. These results demonstrate the powerful effect of GSTT1 status on SPMA levels in urine and show that uptake of benzene in African American, White, and Japanese American cigarette smokers is consistent with their lung cancer risk in the MEC. While benzene is not generally considered a cause of lung cancer, its metabolite SPMA could be a biomarker for other volatile lung carcinogens in cigarette smoke. PMID:26959369

  6. Is nutrient uptake by plant roots sensitive to the rate of mass flow? Reappraisal of an old chestnut for spatially distributed root systems

    NASA Astrophysics Data System (ADS)

    McMurtrie, R. E.; Näsholm, T.

    2015-12-01

    Numerous modelling papers have considered the contribution of mass flow to nutrient uptake by a single plant root, but few have evaluated its contribution at the scale of an entire root system. We derive equations for nitrogen (N) influx per unit root surface area (J) and N uptake by a single root (U) as functions of soil nitrogen supply, root-length density (RLD) and the velocity of water at the root surface (vo). This model of N uptake by a single root can be used to evaluate N uptake by an entire root system if spatial distributions are known for soil N supply, root biomass and water-uptake velocity. In this paper we show that spatial distributions of RLD and vo can be estimated simultaneously under an optimisation hypothesis (MaxNup, McMurtrie et al. 2012), according to which total root mass and total water uptake are distributed vertically in order to maximise total N uptake. The MaxNup hypothesis leads to equations for optimal vertical profiles of RLD, vo, J and U, maximum rooting depth and the fraction of total available soil nitrogen taken up by the root system. Predicted values of vo are enhanced at depths where nitrogen influx per unit root surface area (J) is more sensitive to vo and diminished at depths where J is less sensitive to vo. Predicted vo is largest at the base of the root system where RLD is lowest, and is smallest in upper soil layers where RLD is highest. MaxNup thus predicts that water uptake will be distributed preferentially to soil depths where it will enhance nitrogen uptake U; this tendency will amplify the sensitivity of total N uptake to total water uptake, compared with strategies where vo is the same for all roots, or where vo is elevated for roots in upper soil layers. Reference McMurtrie RE, Iversen CM, Dewar RC, Medlyn BE, Näsholm T, Pepper DA, Norby RJ. 2012. Plant root distributions and nitrogen uptake predicted by a hypothesis of optimal root foraging. Ecology and Evolution 2: 1235-1250.

  7. Tested Demonstrations: Color Oscillations in the Formic Acid-Nitric Acid-Sulfuric Acid System.

    ERIC Educational Resources Information Center

    Raw, C. J. G.; And Others

    1983-01-01

    Presented are procedures for demonstrating the production of color oscillations when nitric acid is added to a formic acid/concentrated sulfuric acid mixture. Because of safety considerations, "Super-8" home movie of the color changes was found to be satisfactory for demonstration purposes. (JN)

  8. A Cell-Targeted, Size-Photocontrollable, Nuclear-Uptake Nanodrug Delivery System for Drug-Resistant Cancer Therapy

    PubMed Central

    2015-01-01

    The development of multidrug resistance (MDR) has become an increasingly serious problem in cancer therapy. The cell-membrane overexpression of P-glycoprotein (P-gp), which can actively efflux various anticancer drugs from the cell, is a major mechanism of MDR. Nuclear-uptake nanodrug delivery systems, which enable intranuclear release of anticancer drugs, are expected to address this challenge by bypassing P-gp. However, before entering the nucleus, the nanocarrier must pass through the cell membrane, necessitating coordination between intracellular and intranuclear delivery. To accommodate this requirement, we have used DNA self-assembly to develop a nuclear-uptake nanodrug system carried by a cell-targeted near-infrared (NIR)-responsive nanotruck for drug-resistant cancer therapy. Via DNA hybridization, small drug-loaded gold nanoparticles (termed nanodrugs) can self-assemble onto the side face of a silver–gold nanorod (NR, termed nanotruck) whose end faces were modified with a cell type-specific internalizing aptamer. By using this size-photocontrollable nanodrug delivery system, anticancer drugs can be efficiently accumulated in the nuclei to effectively kill the cancer cells. PMID:25479133

  9. A cell-targeted, size-photocontrollable, nuclear-uptake nanodrug delivery system for drug-resistant cancer therapy.

    PubMed

    Qiu, Liping; Chen, Tao; Öçsoy, Ismail; Yasun, Emir; Wu, Cuichen; Zhu, Guizhi; You, Mingxu; Han, Da; Jiang, Jianhui; Yu, Ruqin; Tan, Weihong

    2015-01-14

    The development of multidrug resistance (MDR) has become an increasingly serious problem in cancer therapy. The cell-membrane overexpression of P-glycoprotein (P-gp), which can actively efflux various anticancer drugs from the cell, is a major mechanism of MDR. Nuclear-uptake nanodrug delivery systems, which enable intranuclear release of anticancer drugs, are expected to address this challenge by bypassing P-gp. However, before entering the nucleus, the nanocarrier must pass through the cell membrane, necessitating coordination between intracellular and intranuclear delivery. To accommodate this requirement, we have used DNA self-assembly to develop a nuclear-uptake nanodrug system carried by a cell-targeted near-infrared (NIR)-responsive nanotruck for drug-resistant cancer therapy. Via DNA hybridization, small drug-loaded gold nanoparticles (termed nanodrugs) can self-assemble onto the side face of a silver-gold nanorod (NR, termed nanotruck) whose end faces were modified with a cell type-specific internalizing aptamer. By using this size-photocontrollable nanodrug delivery system, anticancer drugs can be efficiently accumulated in the nuclei to effectively kill the cancer cells. PMID:25479133

  10. Bioactive and metal uptake studies of carboxymethyl chitosan-graft-D-glucuronic acid membranes for tissue engineering and environmental applications.

    PubMed

    Jayakumar, R; Rajkumar, M; Freitas, H; Sudheesh Kumar, P T; Nair, S V; Furuike, T; Tamura, H

    2009-08-01

    Carboxymethyl chitosan-graft-D-glucuronic acid (CMCS-g-D-GA) was prepared by grafting D-GA onto CMCS in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and then the membranes were made from it. In this work, the bioactivity studies of CMCS-g-D-GA membranes were carried out and then characterized by SEM, CLSM, XRD and FT-IR. The CMCS-g-D-GA membranes were found to be bioactive. The adsorption of Ni2+, Zn2+ and Cu2+ ions onto CMCS-g-D-GA membranes has also been investigated. The maximum adsorption capacity of CMCS-g-D-GA for Ni2+, Zn2+ and Cu2+ was found to be 57, 56.4 and 70.2 mg/g, respectively. Hence, these membranes were useful for tissue engineering, environmental and water purification applications. PMID:19409415

  11. Phytosiderophores revisited: 2′-deoxymugineic acid-mediated iron uptake triggers nitrogen assimilation in rice (Oryza sativa L.) seedlings

    PubMed Central

    Araki, Ryoichi; Namba, Kosuke; Murata, Yoshiko; Murata, Jun

    2015-01-01

    Poaceae plants release phytosiderophores into the rhizosphere in order to chelate iron (Fe), which often exists in insoluble forms especially under high pH conditions. The impact of phytosiderophore treatment at the physiological and molecular levels in vivo remains largely elusive, although the biosynthesis of phytosiderophores and the transport of phytosiderophore-metal complexes have been well studied. We recently showed that the application of 30 μM of the chemically synthesized phytosiderophore 2′-deoxymugineic acid (DMA) was sufficient for apparent full recovery of otherwise considerably reduced growth of hydroponic rice seedlings at high pH. Moreover, unexpected induction of high-affinity nitrate transporter gene expression as well as nitrate reductase activity indicates that the nitrate response is linked to Fe homeostasis. These data shed light on the biological relevance of DMA not simply as a Fe chelator, but also as a trigger that promotes plant growth by reinforcing nitrate assimilation. PMID:26023724

  12. Reduction in uptake by rice and soybean of aromatic arsenicals from diphenylarsinic acid contaminated soil amended with activated charcoal.

    PubMed

    Arao, Tomohito; Maejima, Yuji; Baba, Koji

    2011-10-01

    Activated charcoal (AC) amendment has been suggested as a promising method to immobilize organic contaminants in soil. We performed pot experiments with rice and soybean grown in agricultural soil polluted by aromatic arsenicals (AAs). The most abundant AA in rice grains and soybean seeds was methylphenylarsinic acid (MPAA). MPAA concentration in rice grains was significantly reduced to 2% and 3% in 0.2% AC treated soil compared to untreated soil in the first year of rice cultivation. In the second year, MPAA concentration in rice grains was significantly reduced to 15% in 0.2% AC treated soil compared to untreated soil. MPAA concentration in soybean seeds was significantly reduced to 44% in 0.2% AC treated soil compared to untreated soil. AC amendment was effective in reducing AAs in rice and soybean. PMID:21782301

  13. Ultrastructural characterization of gerbil olivocochlear neurons based on differential uptake of /sup 3/H-D-aspartic acid and a wheatgerm agglutinin-horseradish peroxidase conjugate from the cochlea

    SciTech Connect

    Helfert, R.H.; Schwartz, I.R.; Ryan, A.F.

    1988-09-01

    Two populations of olivocochlear (OC) neurons have been identified in the gerbil brain stem on the basis of differential labeling patterns of 3H-D-aspartic acid (D-ASP) and wheatgerm agglutinin-horseradish peroxidase conjugate (WGA/HRP) from the cochlear perilymph. While both populations are capable of uptake and retrograde uptake of WGA/HRP, one population accumulates and retrogradely transports D-ASP (D-ASP OC neurons) and the other does not (non-D-ASP OC neurons). D-ASP OC neurons are found in or near the lateral superior olive, are small in size, and receive very few synaptic contacts. The vast majority of these synapses contain small, mildly pleomorphic vesicles with scattered dense core vesicles. Synapses with distinctly larger pleomorphic vesicles have also been observed. These neurons possess all of the features common to neurons of the lateral olivocochlear system. Non-D-ASP OC neurons are found primarily in the ventral nucleus of the trapezoid body, as well as in the area between the medial superior olive and the medial nucleus of the trapezoid body. These neurons are larger and receive greater numbers and types of synaptic contacts than those found on D-ASP OC neurons. The 2 most common synapses found on non-D-ASP OC neurons are axosomatic ones containing small, mildly pleomorphic vesicles and scattered dense core vesicles similar to those seen on the D-ASP OC neurons, and axodendritic synapses containing large, round vesicles. Much less frequently observed are synapses containing small, round vesicles or ones containing predominantly flat vesicles. The ultrastructural features of the non-D-ASP OC neurons correspond to those described for neurons of the medial olivocochlear system.

  14. Stimulation of glycolysis and amino acid uptake in NRK-49F cells by transforming growth factor beta and epidermal growth factor.

    PubMed Central

    Boerner, P; Resnick, R J; Racker, E

    1985-01-01

    Glycolysis in normal resting rat kidney cells (NRK-49F) was stimulated by a 2-hr exposure to transforming growth factors prior to assay. Transforming growth factor beta (TGF-beta) was effective when added alone, and further addition of epidermal growth factor (EGF) had little effect. The stimulation by TGF-beta was abolished when cycloheximide was present during the incubation, suggesting that protein synthesis is required for the effect. Incubation of the cells with 25 mM methionine abolished the stimulation of glycolysis by TGF-beta. The uptake of methylaminoisobutyrate via system A was stimulated by either TGF-beta or EGF. The greater than 3-fold stimulation of uptake by 1 ng of pure TGF-beta per ml was usually somewhat enhanced on addition of 0.5 ng of EGF per ml. Moreover, an antiserum against EGF receptor partially depressed the response to TGF-beta, suggesting some overlapping interactions of EGF and TGF-beta. Images PMID:3871948

  15. Hexachlorobenzene uptake by fathead minnows and macroinvertebrates in recirculating sediment/water systems

    SciTech Connect

    Schuytema, G.S.; Krawczyk, D.F.; Griffis, W.L.; Nebeker, A.V.; Robideaux, M.L.

    1990-01-01

    Fathead minnow (Pimephales promelas), the worm, Lumbriculus variegatus, and the amphipods Hyalella azteca and Gammarus lacustris were exposed to hexachlorobenzene (HCB) in water with and without a bed of HCB-spiked sediment. Water HCB concentrations were maintained by recirculation through HCB-packed columns. Recirculating HCB-bound particulates and possibly eroded HCB particulates were an added source of HCB in addition to the sediment bed. Significant bioaccumulation of HCB in animal tissues was observed in water-only and water-sediment exposures. The presence of the HCB-spiked sediment did not result in a significant increase in the uptake of HCB by the organisms, but there was a substantial increase in sediment HCB levels over time. Higher tissue HCB levels in aquaria without sediment suggest that the sediment was a more efficient sink for HCB than the organisms.

  16. Continuous-flow free acid monitoring method and system

    DOEpatents

    Strain, J.E.; Ross, H.H.

    1980-01-11

    A free acid monitoring method and apparatus is provided for continuously measuring the excess acid present in a process stream. The disclosed monitoring system and method is based on the relationship of the partial pressure ratio of water and acid in equilibrium with an acid solution at constant temperature. A portion of the process stream is pumped into and flows through the monitor under the influence of gravity and back to the process stream. A continuous flowing sample is vaporized at a constant temperature and the vapor is subsequently condensed. Conductivity measurements of the condensate produces a nonlinear response function from which the free acid molarity of the sample process stream is determined.

  17. Continuous-flow free acid monitoring method and system

    DOEpatents

    Strain, James E.; Ross, Harley H.

    1981-01-01

    A free acid monitoring method and apparatus is provided for continuously measuring the excess acid present in a process stream. The disclosed monitoring system and method is based on the relationship of the partial pressure ratio of water and acid in equilibrium with an acid solution at constant temperature. A portion of the process stream is pumped into and flows through the monitor under the influence of gravity and back to the process stream. A continuous flowing sample is vaporized at a constant temperature and the vapor is subsequently condensed. Conductivity measurements of the condensate produces a nonlinear response function from which the free acid molarity of the sample process stream is determined.

  18. 'Alperujo' compost amendment of contaminated calcareous and acidic soils: effects on growth and trace element uptake by five Brassica species.

    PubMed

    Fornes, Fernando; García-de-la-Fuente, Rosana; Belda, Rosa M; Abad, Manuel

    2009-09-01

    The effects of 'alperujo' compost on trace element availability and on microbial activity of two contaminated soils, a calcareous soil (S1) with high contents of Pb and Zn, and an acidic soil (S2) with a substantial amount of Al, As, Pb and Zn, were assessed. Additionally, the growth and capacity for contaminant phytoextraction of five Brassica species were studied. Compost amendment did not affect S1, but in S2 it increased soil pH, thus reducing Al and Zn bioavailability and toxicity. Compost application also increased microbial population and bioactivity in both soils. Brassica plants did not survive in S2, yet they thrived in S1. When compost was applied to S2, Brassica carinata, Brassica napus and Brassica oleracea grew adequately. Considering both the capacity to accumulate trace elements in the shoot and the ability to grow in the contaminated soils tested, the most efficient phytoextractors were Brassica juncea in S1 (particularly for Zn) and Brassica oleracea in S2 (for Al, As, Pb and Zn). PMID:19369067

  19. Uptake of a web-based oncology protocol system: how do cancer clinicians use eviQ cancer treatments online?

    PubMed Central

    2013-01-01

    Background The use of computerized systems to support evidence-based practice is commonplace in contemporary medicine. Despite the prolific use of electronic support systems there has been relatively little research on the uptake of web-based systems in the oncology setting. Our objective was to examine the uptake of a web-based oncology protocol system (http://www.eviq.org.au) by Australian cancer clinicians. Methods We used web-logfiles and Google Analytics to examine the characteristics of eviQ registrants from October 2009-December 2011 and patterns of use by cancer clinicians during a typical month. Results As of December 2011, there were 16,037 registrants; 85% of whom were Australian health care professionals. During a typical month 87% of webhits occurred in standard clinical hours (08:00 to 18:00 weekdays). Raw webhits were proportional to the size of clinician groups: nurses (47% of Australian registrants), followed by doctors (20%), and pharmacists (14%). However, pharmacists had up to three times the webhit rate of other clinical groups. Clinicians spent five times longer viewing chemotherapy protocol pages than other content and the protocols viewed reflect the most common cancers: lung, breast and colorectal. Conclusions Our results demonstrate eviQ is used by a range of health professionals involved in cancer treatment at the point-of-care. Continued monitoring of electronic decision support systems is vital to understanding how they are used in clinical practice and their impact on processes of care and patient outcomes. PMID:23497080