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Sample records for anion transporters oat1

  1. Flavonoids Are Inhibitors of Human Organic Anion Transporter 1 (OAT1)–Mediated Transport

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    An, Guohua; Wang, Xiaodong

    2014-01-01

    Organic anion transporter 1 (OAT1) has been reported to be involved in the nephrotoxicity of many anionic xenobiotics. As current clinically used OAT1 inhibitors are often associated with safety issues, identifying potent OAT1 inhibitors with little toxicity is of great value in reducing OAT1-mediated drug nephrotoxicity. Flavonoids are a class of polyphenolic compounds with exceptional safety records. Our objective was to evaluate the effects of 18 naturally occurring flavonoids, and some of their glycosides, on the uptake of para-aminohippuric acid (PAH) in both OAT1-expressing and OAT1-negative LLC-PK1 cells. Most flavonoid aglycones produced substantial decreases in PAH uptake in OAT1-expressing cells. Among the flavonoids screened, fisetin, luteolin, morin, and quercetin exhibited the strongest effect and produced complete inhibition of OAT1-mediated PAH uptake at a concentration of 50 μM. Further concentration-dependent studies revealed that both morin and luteolin are potent OAT1 inhibitors, with IC50 values of flavonoid aglycones, all flavonoid glycosides had negligible or small effects on OAT1. In addition, the role of OAT1 in the uptake of fisetin, luteolin, morin, and quercetin was investigated and fisetin was found to be a substrate of OAT1. Taken together, our results indicate that flavonoids are a novel class of OAT1 modulators. Considering the high consumption of flavonoids in the diet and in herbal products, OAT1-mediated flavonoid-drug interactions may be clinically relevant. Further investigation is warranted to evaluate the nephroprotective role of flavonoids in relation to drug-induced nephrotoxicity mediated by the OAT1 pathway. PMID:25002746

  2. Impact of the induced organic anion transporter 1 (Oat1) renal expression by furosemide on the pharmacokinetics of organic anions.

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    Severin, María Julia; Hazelhoff, María Herminia; Bulacio, Romina Paula; Mamprin, María Eugenia; Brandoni, Anabel; Torres, Adriana Mónica

    2017-08-01

    Furosemide is a loop diuretic. Different authors demonstrated that continuous administration of furosemide modulates the expression of organic anion transporters. This study was undertaken to simultaneously evaluate the effects of furosemide pretreatment on organic anion transporter 1 (Oat1) and multidrug resistance protein 2 (Mrp2) renal expressions, on p-aminohippurate (PAH) pharmacokinetics and on renal and urinary PAH levels in rats. Male Wistar rats were treated with furosemide (6 mg/100 g body weight per day, subcutaneously, 4 days) (treated group) or saline (control group). On the fifth day, PAH was administered as a bolus infusion in the femoral vein, and plasma samples were obtained from femoral artery at different time points. PAH levels in renal tissue and urine were also assessed. Renal Oat1 and Mrp2 expressions were evaluated by western blotting. Furosemide pretreatment increased both the expression of Oat1 and Mrp2. PAH plasma concentrations decreased following a biexponential function. The furosemide-treated group showed higher PAH plasma levels, a lower systemic clearance and elimination rate constant from the peripheral compartment, indicating that PAH renal elimination was decreased. PAH levels in renal tissue were significantly elevated and in urine appeared to be significantly lower as compared with control animals. Furosemide pretreatment caused a significant decrease of PAH renal elimination, despite Oat1 and Mrp2 augmented renal expression. The goal of the present study is the addition of important information in the wide gap of knowledge that exists about drug-drug interactions. Because of furosemide worldwide use, the data obtained are interesting and useful in terms of translation to clinical practice. © 2016 Asian Pacific Society of Nephrology.

  3. Male-dominant activation of rat renal organic anion transporter 1 (Oat1 and 3 (Oat3 expression by transcription factor BCL6.

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    Waja Wegner

    Full Text Available BACKGROUND: Organic anion transporters 1 (Oat1 and 3 (Oat3 mediate the transport of organic anions, including frequently prescribed drugs, across cell membranes in kidney proximal tubule cells. In rats, these transporters are known to be male-dominant and testosterone-dependently expressed. The molecular mechanisms that are involved in the sex-dependent expression are unknown. Our aim was to identify genes that show a sex-dependent expression and could be involved in male-dominant regulation of Oat1 and Oat3. METHODOLOGY/PRINCIPAL FINDINGS: Promoter activities of Oat1 and Oat3 were analyzed using luciferase assays. Expression profiling was done using a SurePrint G3 rat GE 8 × 60K microarray. RNA was isolated from renal cortical slices of four adult rats per sex. To filter the achieved microarray data for genes expressed in proximal tubule cells, transcription database alignment was carried out. We demonstrate that predicted androgen response elements in the promoters of Oat1 and Oat3 are not functional when the promoters were expressed in OK cells. Using microarray analyses we analyzed 17,406 different genes. Out of these genes, 56 exhibit a sex-dependent expression in rat proximal tubule cells. As genes potentially involved in the regulation of Oat1 and Oat3 expression, we identified, amongst others, the male-dominant hydroxysteroid (17-beta dehydrogenase 1 (Hsd17b1, B-cell CLL/lymphoma 6 (BCL6, and polymerase (RNA III (DNA directed polypeptide G (Polr3g. Moreover, our results revealed that the transcription factor BCL6 activates promoter constructs of Oat1 and Oat3. CONCLUSION: The results indicate that the male-dominant expression of both transporters, Oat1 and Oat3, is possibly not directly regulated by the classical androgen receptor mediated transcriptional pathway but appears to be regulated by the transcription factor BCL6.

  4. α-Ketoglutarate-related inhibitors of HIF prolyl hydroxylases are substrates of renal organic anion transporters 1 (OAT1) and 4 (OAT4).

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    Hagos, Yohannes; Schley, Gunnar; Schödel, Johannes; Krick, Wolfgang; Burckhardt, Gerhard; Willam, Carsten; Burckhardt, Birgitta C

    2012-10-01

    2-Oxoglutarate or α-ketoglutarate (αKG) is a substrate of HIF prolyl hydroxylases 1-3 that decrease cellular levels of the hypoxia-inducible factor 1α (HIF-1α) in the presence of oxygen. αKG analogs are applied to stabilize HIF-1α even in the presence of oxygen and thus provide a novel therapeutic option in treating kidney diseases. In the kidneys, the organic anion transporters 1 and 3 (OAT1 and OAT3, respectively) in cooperation with the sodium-dependent dicarboxylate transporter 3 (NaDC3) and the OAT4 might be responsible for the uptake of αKG analogs into and the efflux out of the tubular cells. Using the radiolabelled substrates p-aminohippurate (PAH, OAT1), estrone-3-sulfate (ES; OAT3, OAT4), and succinate (NaDC3), N-oxalylglycine (NOG), dimethyloxalyl glycine (DMOG), 2,4-diethylpyridine dicarboxylate (2,4-DPD), and pyridine-2,4-dicarboxylic acid (PDCA) were tested in cis-inhibition and trans-stimulation experiments. None of these αKG analogs interacted with NaDC3. 2,4-DPD and PDCA inhibited ES uptake by OAT3 moderately. NOG, 2,4-DPD and PDCA, but not DMOG, inhibited PAH uptake by OAT1 significantly. trans-Stimulation experiments and experiments demonstrating stabilization of HIF-1α revealed that NOG and PDCA, but not 2,4-DPD, are translocated by OAT1. All compounds trans-stimulated ES uptake by OAT4, but only PDCA stabilized HIF-1α. The data suggest that OAT1 is involved in the uptake of NOG and PDCA across the basolateral membrane of proximal tubule cells, whereas OAT4 may release these compounds into the primary urine.

  5. Organic anion and cation SLC22 "drug" transporter (Oat1, Oat3, and Oct1 regulation during development and maturation of the kidney proximal tubule.

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    Thomas F Gallegos

    Full Text Available Proper physiological function in the pre- and post-natal proximal tubule of the kidney depends upon the acquisition of selective permeability, apical-basolateral epithelial polarity and the expression of key transporters, including those involved in metabolite, toxin and drug handling. Particularly important are the SLC22 family of transporters, including the organic anion transporters Oat1 (originally identified as NKT and Oat3 as well as the organic cation transporter Oct1. In ex vivo cultures of metanephric mesenchyme (MM; the embryonic progenitor tissue of the nephron Oat function was evident before completion of nephron segmentation and corresponded with the maturation of tight junctions as measured biochemically by detergent extractability of the tight junction protein, ZO-1. Examination of available time series microarray data sets in the context of development and differentiation of the proximal tubule (derived from both in vivo and in vitro/ex vivo developing nephrons allowed for correlation of gene expression data to biochemically and functionally defined states of development. This bioinformatic analysis yielded a network of genes with connectivity biased toward Hnf4α (but including Hnf1α, hyaluronic acid-CD44, and notch pathways. Intriguingly, the Oat1 and Oat3 genes were found to have strong temporal co-expression with Hnf4α in the cultured MM supporting the notion of some connection between the transporters and this transcription factor. Taken together with the ChIP-qPCR finding that Hnf4α occupies Oat1, Oat3, and Oct1 proximal promoters in the in vivo differentiating rat kidney, the data suggest a network of genes with Hnf4α at its center plays a role in regulating the terminal differentiation and capacity for drug and toxin handling by the nascent proximal tubule of the kidney.

  6. Regulation of Expression of Renal Organic Anion Transporters OAT1 and OAT3 in a Model of Ischemia/Reperfusion Injury

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    Christina Preising

    2015-08-01

    Full Text Available Background: Recently, we gained evidence that impairment of rOat1 and rOat3 expression induced by ischemic acute kidney injury (AKI is mediated by COX metabolites and this suppression might be critically involved in renal damage. Methods: (i Basolateral organic anion uptake into proximal tubular cells after model ischemia and reperfusion (I/R was investigated by fluorescein uptake. The putative promoter sequences from hOAT1 (SLC22A6 and hOAT3 (SCL22A8 were cloned into a reporter plasmid, transfected into HEK cells and (ii transcriptional activity was determined after model ischemia and reperfusion as a SEAP reporter gen assay. Inhibitors or antagonists were applied with the beginning of reperfusion. Results: By using inhibitors of PKA (H89 and PLC (U73122, antagonists of E prostanoid receptor type 2 (AH6809 and type 4 (L161,982, we gained evidence that I/R induced down regulation of organic anion transport is mediated by COX1 metabolites via E prostanoid receptor type 4. The latter signaling was confirmed by application of butaprost (EP2 agonist or TCS2510 (EP4 agonist to control cells. In brief, the latter signaling was verified for the transcriptional activity in the reporter gen assay established. Therein, selective inhibitors for COX1 (SC58125 and COX2 (SC560 were also applied. Conclusion: Our data show (a that COX1 metabolites are involved in the regulation of renal organic anion transport(ers after I/R via the EP4 receptor and (b that this is due to transcriptional regulation of the respective transporters. As the promoter sequences cloned were of human origin and expressed in a human renal epithelial cell line we (c hypothesize that the regulatory mechanisms described after I/R is meaningful for humans as well.

  7. Low doses of ochratoxin A upregulate the protein expression of organic anion transporters Oat1, Oat2, Oat3 and Oat5 in rat kidney cortex

    International Nuclear Information System (INIS)

    Zlender, Vilim; Breljak, Davorka; Ljubojevic, Marija; Flajs, Dubravka; Balen, Daniela; Brzica, Hrvoje; Domijan, Ana-Marija; Peraica, Maja; Fuchs, Radovan; Anzai, Naohiko; Sabolic, Ivan

    2009-01-01

    Mycotoxin ochratoxin A (OTA) is nephrotoxic in various animal species. In rodents, OTA intoxication impairs various proximal tubule (PT) functions, including secretion of p-aminohippurate (PAH), possibly via affecting the renal organic anion (OA) transporters (Oat). However, an effect of OTA on the activity/expression of specific Oats in the mammalian kidney has not been reported. In this work, male rats were gavaged various doses of OTA every 2nd day for 10 days, and in their kidneys we studied: tubule integrity by microscopy, abundance of basolateral (rOat1, rOat3) and brush-border (rOat2, rOat5) rOat proteins by immunochemical methods, and expression of rOats mRNA by RT-PCR. The OTA treatment caused: a) dose-dependent damage of the cells in S3 segments of medullary rays, b) dual effect upon rOats in PT: low doses (50-250 μg OTA/kg b.m.) upregulated the abundance of all rOats, while a high dose (500 μg OTA/kg b.m.) downregulated the abundance of rOat1, and c) unchanged mRNA expression for all rOats at low OTA doses, and its downregulation at high OTA dose. Changes in the expression of renal Oats were associated with enhanced OTA accumulation in tissue and excretion in urine, whereas the indicators of oxidative stress either remained unchanged (malondialdehyde, glutathione, 8-hydroxydeoxyguanosine) or became deranged (microtubules). While OTA accumulation and downregulation of rOats in the kidney are consistent with the previously reported impaired renal PAH secretion in rodents intoxicated with high OTA doses, the post-transcriptional upregulation of Oats at low OTA doses may contribute to OTA accumulation and development of nephrotoxicity.

  8. Inhibitory effects of p-aminohippurate and probenecid on the renal clearance of adefovir and benzylpenicillin as probe drugs for organic anion transporter (OAT) 1 and OAT3 in humans.

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    Maeda, Kazuya; Tian, Ying; Fujita, Tomoe; Ikeda, Yasuhiko; Kumagai, Yuji; Kondo, Tsunenori; Tanabe, Kazunari; Nakayama, Hideki; Horita, Shigeru; Kusuhara, Hiroyuki; Sugiyama, Yuichi

    2014-08-01

    Probe substrates for, and inhibitors of, specific transporters are desired to evaluate quantitatively the in vivo functions of transporters in humans. Based on published data, adefovir and benzylpenicillin were selected as organic anion transporter (OAT) 1- and OAT3-selective probe substrates, respectively. In human kidney slices, probenecid potently inhibited the uptake of both adefovir and benzylpenicillin with inhibition constant (Ki) values of 18.6±5.1 and 12.6±4.2μM, respectively, whereas p-aminohippurate (PAH) preferentially inhibited adefovir uptake. A clinical drug-interaction study involving healthy subjects was performed to investigate the dose-dependent inhibition potencies of probenecid and PAH on the renal clearance of the probe substrates. Adefovir or benzylpenicillin was coadministered with different oral doses of probenecid (500, 750, or 1500mg) or intravenous PAH infusion rates (70, 120, or 210mg/min/person) to the same subject using a crossover design. The renal clearance of adefovir was reduced by 45% and 46% in the subjects treated with the maximum dose of probenecid and PAH, respectively, which was in accordance with the results of in vitro inhibition study. On the other hand, renal clearance of benzylpenicillin was reduced by 78% in the subjects treated with the maximum dose of probenecid (1500mg), which could be explained by its in vitro Ki values. However, PAH unexpectedly increased the renal clearance of benzylpenicillin by 47%. These results suggest that adefovir and benzylpenicillin can be used as probe drugs for OAT1 and OAT3, respectively, and that PAH can be used to investigate the role of OAT1 in the urinary excretion of drugs in humans, whereas it may modulate other transport processes in the kidney. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Molecular Properties of Drugs Interacting with SLC22 Transporters OAT1, OAT3, OCT1, and OCT2: A Machine-Learning Approach.

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    Liu, Henry C; Goldenberg, Anne; Chen, Yuchen; Lun, Christina; Wu, Wei; Bush, Kevin T; Balac, Natasha; Rodriguez, Paul; Abagyan, Ruben; Nigam, Sanjay K

    2016-10-01

    Statistical analysis was performed on physicochemical descriptors of ∼250 drugs known to interact with one or more SLC22 "drug" transporters (i.e., SLC22A6 or OAT1, SLC22A8 or OAT3, SLC22A1 or OCT1, and SLC22A2 or OCT2), followed by application of machine-learning methods and wet laboratory testing of novel predictions. In addition to molecular charge, organic anion transporters (OATs) were found to prefer interacting with planar structures, whereas organic cation transporters (OCTs) interact with more three-dimensional structures (i.e., greater SP3 character). Moreover, compared with OAT1 ligands, OAT3 ligands possess more acyclic tetravalent bonds and have a more zwitterionic/cationic character. In contrast, OCT1 and OCT2 ligands were not clearly distinquishable form one another by the methods employed. Multiple pharmacophore models were generated on the basis of the drugs and, consistent with the machine-learning analyses, one unique pharmacophore created from ligands of OAT3 possessed cationic properties similar to OCT ligands; this was confirmed by quantitative atomic property field analysis. Virtual screening with this pharmacophore, followed by transport assays, identified several cationic drugs that selectively interact with OAT3 but not OAT1. Although the present analysis may be somewhat limited by the need to rely largely on inhibition data for modeling, wet laboratory/in vitro transport studies, as well as analysis of drug/metabolite handling in Oat and Oct knockout animals, support the general validity of the approach-which can also be applied to other SLC and ATP binding cassette drug transporters. This may make it possible to predict the molecular properties of a drug or metabolite necessary for interaction with the transporter(s), thereby enabling better prediction of drug-drug interactions and drug-metabolite interactions. Furthermore, understanding the overlapping specificities of OATs and OCTs in the context of dynamic transporter tissue

  10. Uraemic toxins induce proximal tubular injury via organic anion transporter 1-mediated uptake

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    Motojima, Masaru; Hosokawa, Atsuko; Yamato, Hideyuki; Muraki, Takamura; Yoshioka, Toshimasa

    2002-01-01

    A direct effect of uraemic toxins in promoting progression of chronic renal disease has not been established. In this study, we investigated the toxic effects of organic anions which characteristically appeared in the patients with progressive renal disease on renal proximal tubular cells expressing human organic anion transporter (hOAT) 1. A renal proximal tubular cell line, opossum kidney (OK) cells, was transformed with hOAT1. Among the organic anions examined, hippuric acid, para-hydroxyhippuric acid, ortho-hydroxyhippuric acid, indoxyl sulphate and indoleacetic acid showed a high affinity for hOAT1 expressed in the OK cells. Indoxyl sulphate and indoleacetic acid concentration-dependently inhibited proliferation of the hOAT1-transformed cells. The h.p.l.c. analysis demonstrated that cellular uptake of these organic anions was significantly elevated in hOAT1-transformed cells. These organic anions also concentration-dependently stimulated cellular free radical production. The degrees of inhibition of cell proliferation and the stimulation of free radical production induced by the organic anions were significantly higher in the hOAT1-transformed cells than vector-transformed cells. The stimulatory effect of indoxyl sulphate on free radical production was abolished by anti-oxidants and probenecid. Less free radical production was observed in the hOAT1-transformed cells treated with p-hydroxyhippuric acid, o-hydroxyhippuric acid compared with indoxyl sulphate and indoleacetic acid. Hippuric acid had little effect on free radical production. Organic anions present in the serum of patients with progressive renal disease may cause proximal tubular injury via hOAT1-mediated uptake. The mechanism of cellular toxicity by these uraemic toxins involves free radical production. Thus, some uraemic toxins may directly promote progression of chronic renal disease. PMID:11815391

  11. Organic anion transporter 3- and organic anion transporting polypeptides 1B1- and 1B3-mediated transport of catalposide

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    Jeong HU

    2015-01-01

    Full Text Available Hyeon-Uk Jeong,1 Mihwa Kwon,2 Yongnam Lee,3 Ji Seok Yoo,3 Dae Hee Shin,3 Im-Sook Song,2 Hye Suk Lee1 1College of Pharmacy, The Catholic University of Korea, Bucheon 420-743, Korea; 2College of Pharmacy and Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu 702-701, Korea; 3Central R&D Institute, Yungjin Pharm Co., Ltd., Suwon 443-270, Korea Abstract: We investigated the in vitro transport characteristics of catalposide in HEK293 cells overexpressing organic anion transporter 1 (OAT1, OAT3, organic anion transporting polypeptide 1B1 (OATP1B1, OATP1B3, organic cation transporter 1 (OCT1, OCT2, P-glycoprotein (P-gp, and breast cancer resistance protein (BCRP. The transport mechanism of catalposide was investigated in HEK293 and LLC-PK1 cells overexpressing the relevant transporters. The uptake of catalposide was 319-, 13.6-, and 9.3-fold greater in HEK293 cells overexpressing OAT3, OATP1B1, and OATP1B3 transporters, respectively, than in HEK293 control cells. The increased uptake of catalposide via the OAT3, OATP1B1, and OATP1B3 transporters was decreased to basal levels in the presence of representative inhibitors such as probenecid, furosemide, and cimetidine (for OAT3 and cyclosporin A, gemfibrozil, and rifampin (for OATP1B1 and OATP1B3. The concentration-dependent OAT3-mediated uptake of catalposide revealed the following kinetic parameters: Michaelis constant (Km =41.5 µM, maximum uptake rate (Vmax =46.2 pmol/minute, and intrinsic clearance (CLint =1.11 µL/minute. OATP1B1- and OATP1B3-mediated catalposide uptake also showed concentration dependency, with low CLint values of 0.035 and 0.034 µL/minute, respectively. However, the OCT1, OCT2, OAT1, P-gp, and BCRP transporters were apparently not involved in the uptake of catalposide into cells. In addition, catalposide inhibited the transport activities of OAT3, OATP1B1, and OATP1B3 with half-maximal inhibitory concentration values of 83, 200, and 235 µ

  12. Interaction between rhein acyl glucuronide and methotrexate based on human organic anion transporters.

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    Yuan, Yuan; Yang, Hua; Kong, Linghua; Li, Yuan; Li, Ping; Zhang, Hongjian; Ruan, Jianqing

    2017-11-01

    Rhein, a major bioactive compound of many medicinal herbs and the prodrug of diacerein, is often used with low dose of methotrexate as drug combination to treat rheumatoid arthritis. In this study, potential drug-drug interaction between methotrexate and rhein was investigated based on organic anion transporters (OAT). Our study demonstrated that rhein acyl glucuronide (RAG), the major metabolite of rhein in the human blood circulation, significantly inhibited the uptake of p-aminohippurate in hOAT1 transfected cells with IC 50 value of 691 nM and estrone sulfate uptake in hOAT3 transfected cells with IC 50 value of 78.5 nM. As the substrate of both hOAT1 and hOAT3, the methotrexate transport was significantly inhibited by RAG in hOAT1 transfected cells at 50 μM and hOAT3 transfected cells at 1 μM by 69% and 87%, respectively. Further in vivo study showed that after co-administrated with RAG in rats the AUC 0-24 values of methotrexate increased from 3109 to 5370 ng/mL*hr and the t 1/2 was prolonged by 40.5% (from 7.4 to 10.4 h), demonstrating the inhibitory effect of RAG on methotrexate excretion. In conclusion, rhein acyl glucuronide could significantly decrease the transport of methotrexate by both hOAT1 and hOAT3. The combination use of rhein, diacerein or other rhein-containing herbs with methotrexate may cause obvious drug-drug interaction and require close monitoring for potential drug interaction in clinical practice. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Cumulative organic anion transporter-mediated drug-drug interaction potential of multiple components in salvia miltiorrhiza (danshen) preparations.

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    Wang, Li; Venitz, Jürgen; Sweet, Douglas H

    2014-12-01

    To evaluate organic anion transporter-mediated drug-drug interaction (DDI) potential for individual active components of Danshen (Salvia miltiorrhiza) vs. combinations using in vitro and in silico approaches. Inhibition profiles for single Danshen components and combinations were generated in stably-expressing human (h)OAT1 and hOAT3 cells. Plasma concentration-time profiles for compounds were estimated from in vivo human data using an i.v. two-compartment model (with first-order elimination). The cumulative DDI index was proposed as an indicator of DDI potential for combination products. This index was used to evaluate the DDI potential for Danshen injectables from 16 different manufacturers and 14 different lots from a single manufacturer. The cumulative DDI index predicted in vivo inhibition potentials, 82% (hOAT1) and 74% (hOAT3), comparable with those observed in vitro, 72 ± 7% (hOAT1) and 81 ± 10% (hOAT3), for Danshen component combinations. Using simulated unbound Cmax values, a wide range in cumulative DDI index between manufacturers, and between lots, was predicted. Many products exhibited a cumulative DDI index > 1 (50% inhibition). Danshen injectables will likely exhibit strong potential to inhibit hOAT1 and hOAT3 function in vivo. The proposed cumulative DDI index might improve prediction of DDI potential of herbal medicines or pharmaceutical preparations containing multiple components.

  14. Roles of organic anion transporters (OATs) in renal proximal tubules and their localization.

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    Otani, Naoyuki; Ouchi, Motoshi; Hayashi, Keitaro; Jutabha, Promsuk; Anzai, Naohiko

    2017-03-01

    Organic anions (OAs) are secreted in renal proximal tubules in two steps. In the first step, OAs are transported from the blood through basolateral membranes into proximal tubular cells. The prototypical substrate for renal organic anion transport systems, para-aminohippurate (PAH), is transported across basolateral membranes of proximal tubular cells via OAT1 (SLC22A6) and OAT3 (SLC22A8) against an electrochemical gradient in exchange for intracellular dicarboxylates. In the second step, OAs exit into urine through apical membranes of proximal tubules. This step is thought to be performed by multidrug efflux transporters and a voltage-driven organic anion transporter. However, the molecular nature and precise functional properties of these efflux systems are largely unknown. Recently, we characterized an orphan transporter known as human type I sodium-phosphate transporter 4, hNPT4 (SLC17A3), using the Xenopus oocyte expression system. hNPT4 acts as a voltage-driven efflux transporter ("human OATv1") for several OAs such as PAH, estrone sulfate, diuretic drugs, and urate. Here, we describe a model for an OA secretory pathway in renal tubular cells in which OAs exit cells and enter the tubular lumen via hOATv1 (hNPT4). Additionally, hOATv1 functions as a common renal secretory pathway for both urate and drugs, indicating that hOATv1 may be a leak pathway for excess urate that is reabsorbed via apical URAT1 to control the intracellular urate levels. Therefore, we propose a molecular mechanism for the induction of hyperuricemia by diuretics: the diuretics enter proximal tubular cells via basolateral OAT1 and/or OAT3 and may then interfere with the NPT4-mediated apical urate efflux in the renal proximal tubule.

  15. Probenecid, an organic anion transporter 1 and 3 inhibitor, increases plasma and brain exposure of N-acetylcysteine.

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    Hagos, Fanuel T; Daood, Monica J; Ocque, Jacob A; Nolin, Thomas D; Bayir, Hulya; Poloyac, Samuel M; Kochanek, Patrick M; Clark, Robert S B; Empey, Philip E

    2017-04-01

    1. N-acetylcysteine (NAC) is being investigated as an antioxidant for several conditions including traumatic brain injury, but the mechanism by which it crosses membrane barriers is unknown. We have attempted to understand how the transporter inhibitor, probenecid, affects NAC pharmacokinetics and to evaluate the interaction of NAC with transporters. 2. Juvenile Sprague-Dawley rats were administered NAC alone or in combination with probenecid intraperitoneally. Plasma and brain samples were collected serially and NAC concentrations were measured. Transporter studies were conducted with human embryonic kidney-293 cells that overexpress organic anion transporter (OAT)1 or OAT3 and with human multi-drug resistance-associated protein (MRP)1 or MRP4 membrane vesicles. 3. NAC area under the curve was increased in plasma (1.65-fold) and brain (2.41-fold) by probenecid. The apparent plasma clearance was decreased by 65%. Time- and concentration-dependent NAC uptake that was inhibitable by probenecid was observed with OAT1 and OAT3. No uptake of NAC was observed with MRP1 or MRP4. 4. Our results indicate for the first time that NAC is substrate for OAT1 and OAT3 and that probenecid increases NAC plasma and brain exposure in vivo. These data provide insight regarding how NAC crosses biological barriers and suggest a promising therapeutic strategy to increase NAC exposure.

  16. Structure-affinity relationship in the interactions of human organic anion transporter 1 with caffeine, theophylline, theobromine and their metabolites.

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    Sugawara, Mitsuru; Mochizuki, Takahiro; Takekuma, Yoh; Miyazaki, Katsumi

    2005-08-15

    It is well known that human organic anion transporter 1 (hOAT1) transports many kinds of drugs, endogenous compounds, and toxins. However, little is known about the structure-affinity relationship. The aim of this study was to elucidate the structure-affinity relationship using a series of structurally related compounds that interact with hOAT1. Inhibitory effects of xanthine- and uric acid-related compounds on the transport of p-aminohippuric acid were examined using CHO-K1 cells stably expressing hOAT1. The order of potency for the inhibitory effects of xanthine-related compounds on PAH uptake was 1-methyl derivative>7-methyl derivative>3-methyl derivative falling dotsxanthine>1,3,7-trimethyl derivative (caffeine). The order of potency of the inhibition was 1,3,7-trimethyluric acid>1,3-dimethyluric acid>1,7-dimethyluric acid>1-methyluric acid>uric acid. A significant correlation between inhibitory potency and lipophilicity of the tested uric acid-related compounds was observed. The main determinant of the affinity of xanthine-related compounds is the position of the methyl group. On the other hand, lipophilicity is the main determinant of the affinity of uric acid-related compounds.

  17. The Organic Anion Transporter (OAT) Family: A Systems Biology Perspective

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    Nigam, Sanjay K.; Bush, Kevin T.; Martovetsky, Gleb; Ahn, Sun-Young; Liu, Henry C.; Richard, Erin; Bhatnagar, Vibha; Wu, Wei

    2015-01-01

    The organic anion transporter (OAT) subfamily, which constitutes roughly half of the SLC22 (solute carrier 22) transporter family, has received a great deal of attention because of its role in handling of common drugs (antibiotics, antivirals, diuretics, nonsteroidal anti-inflammatory drugs), toxins (mercury, aristolochic acid), and nutrients (vitamins, flavonoids). Oats are expressed in many tissues, including kidney, liver, choroid plexus, olfactory mucosa, brain, retina, and placenta. Recent metabolomics and microarray data from Oat1 [Slc22a6, originally identified as NKT (novel kidney transporter)] and Oat3 (Slc22a8) knockouts, as well as systems biology studies, indicate that this pathway plays a central role in the metabolism and handling of gut microbiome metabolites as well as putative uremic toxins of kidney disease. Nuclear receptors and other transcription factors, such as Hnf4α and Hnf1α, appear to regulate the expression of certain Oats in conjunction with phase I and phase II drug metabolizing enzymes. Some Oats have a strong selectivity for particular signaling molecules, including cyclic nucleotides, conjugated sex steroids, odorants, uric acid, and prostaglandins and/or their metabolites. According to the “Remote Sensing and Signaling Hypothesis,” which is elaborated in detail here, Oats may function in remote interorgan communication by regulating levels of signaling molecules and key metabolites in tissues and body fluids. Oats may also play a major role in interorganismal communication (via movement of small molecules across the intestine, placental barrier, into breast milk, and volatile odorants into the urine). The role of various Oat isoforms in systems physiology appears quite complex, and their ramifications are discussed in the context of remote sensing and signaling. PMID:25540139

  18. Molecular evidence for an involvement of organic anion transporters (OATs) in aristolochic acid nephropathy

    International Nuclear Information System (INIS)

    Bakhiya, Nadiya; Arlt, Volker M.; Bahn, Andrew; Burckhardt, Gerhard; Phillips, David H.; Glatt, Hansruedi

    2009-01-01

    Aristolochic acid (AA), present in Aristolochia species, is the major causative agent in the development of severe renal failure and urothelial cancers in patients with AA nephropathy. It may also be a cause of Balkan endemic nephropathy. Epithelial cells of the proximal tubule are the primary cellular target of AA. To study whether organic anion transporters (OATs) expressed in proximal tubule cells are involved in uptake of AA, we used human epithelial kidney (HEK293) cells stably expressing human (h) OAT1, OAT3 or OAT4. AA potently inhibited the uptake of characteristic substrates, p-aminohippurate for hOAT1 and estrone sulfate for hOAT3 and hOAT4. Aristolochic acid I (AAI), the more cytotoxic and genotoxic AA congener, exhibited high affinity for hOAT1 (K i = 0.6 μM) as well as hOAT3 (K i = 0.5 μM), and lower affinity for hOAT4 (K i = 20.6 μM). Subsequently, AAI-DNA adduct formation (investigated by 32 P-postlabelling) was used as a measure of AAI uptake. Significantly higher levels of adducts occurred in hOAT-expressing cells than in control cells: this effect was abolished in the presence of the OAT inhibitor probenecid. In Xenopus laevis oocytes hOAT-mediated efflux of p-aminohippurate was trans-stimulated by extracellular AA, providing further molecular evidence for AA translocation by hOATs. Our study indicates that OATs can mediate the uptake of AA into proximal tubule cells and thereby participate in kidney cell damage by this toxin.

  19. Active Hydrophilic Components of the Medicinal Herb Salvia miltiorrhiza (Danshen Potently Inhibit Organic Anion Transporters 1 (Slc22a6 and 3 (Slc22a8

    Directory of Open Access Journals (Sweden)

    Li Wang

    2012-01-01

    Full Text Available Many active components of herbal products are small organic anions, and organic anion transporters were previously demonstrated to be a potential site of drug-drug interactions. In this study, we assessed the inhibitory effects of six hydrophilic components of the herbal medicine Danshen, lithospermic acid, protocatechuic acid, rosmarinic acid, salvianolic acid A, salvianolic acid B, and tanshinol, on the function of the murine organic anion transporters, mOat1 and mOat3. All of Danshen components significantly inhibited mOat1- and mOat3-mediated substrate uptake (<0.001 with lithospermic acid (LSA, protocatechuic acid, rosmarinic acid (RMA, and salvianolic acid A (SAA producing virtually complete inhibition under test conditions. Kinetic analysis demonstrated that LSA, RMA, and SAA were competitive inhibitors. As such, values were estimated as 14.9±4.9 μM for LSA, 5.5±2.2 μM for RMA, and 4.9±2.2 μM for SAA on mOat1-mediated transport, and as 31.1±7.0 μM for LSA, 4.3±0.2 μM for RMA, and 21.3±7.7 μM for SAA on mOat3-mediated transport. These data suggest that herb-drug interactions may occur in vivo on the human orthologs of these transporters in situations of polypharmacy involving Danshen and clinical therapeutics known to be organic anion transporter substrates.

  20. Drug Clearance from Cerebrospinal Fluid Mediated by Organic Anion Transporters 1 (Slc22a6) and 3 (Slc22a8) at Arachnoid Membrane of Rats.

    Science.gov (United States)

    Zhang, Zhengyu; Tachikawa, Masanori; Uchida, Yasuo; Terasaki, Tetsuya

    2018-03-05

    Although arachnoid mater epithelial cells form the blood-arachnoid barrier (BAB), acting as a blood-CSF interface, it has been generally considered that the BAB is impermeable to water-soluble substances and plays a largely passive role. Here, we aimed to clarify the function of transporters at the BAB in regulating CSF clearance of water-soluble organic anion drugs based on quantitative targeted absolute proteomics (QTAP) and in vivo analyses. Protein expression levels of 61 molecules, including 19 ATP-binding-cassette (ABC) transporters and 32 solute-carrier (SLC) transporters, were measured in plasma membrane fraction of rat leptomeninges using QTAP. Thirty-three proteins were detected; others were under the quantification limits. Expression levels of multidrug resistance protein 1 (Mdr1a/P-gp/Abcb1a) and breast cancer resistance protein (Bcrp/Abcg2) were 16.6 and 3.27 fmol/μg protein (51.9- and 9.82-fold greater than in choroid plexus, respectively). Among those organic anion transporters detected only at leptomeninges, not choroid plexus, organic anion transporter 1 (oat1/Slc22a6) showed the greatest expression (2.73 fmol/μg protein). On the other hand, the protein expression level of oat3 at leptomeninges was 6.65 fmol/μg protein, and the difference from choroid plexus was within two-fold. To investigate oat1's role, we injected para-aminohippuric acid (PAH) with or without oat1 inhibitors into cisterna magna (to minimize the contribution of choroid plexus function) of rats. A bulk flow marker, FITC-inulin, was not taken up from CSF up to 15 min, whereas uptake clearance of PAH was 26.5 μL/min. PAH uptake was completely blocked by 3 mM cephalothin (inhibits both oat1 and oat3), while 17% of PAH uptake was inhibited by 0.2 mM cephalothin (selectively inhibits oat3). These results indicate that oat1 and oat3 at the BAB provide a distinct clearance pathway of organic anion drugs from CSF independently of choroid plexus.

  1. Anion transport and GABA signaling

    Directory of Open Access Journals (Sweden)

    Christian Andreas Huebner

    2013-10-01

    Full Text Available Whereas activation of GABAA receptors by GABA usually results in a hyperpolarizing influx of chloride into the neuron, the reversed chloride driving force in the immature nervous system results in a depolarizing efflux of chloride. This GABAergic depolarization is deemed to be important for the maturation of the neuronal network. The concept of a developmental GABA switch has mainly been derived from in vitro experiments and reliable in vivo evidence is still missing. As GABAA receptors are permeable for both chloride and bicarbonate, the net effect of GABA also critically depends on the distribution of bicarbonate. Whereas chloride can either mediate depolarizing or hyperpolarizing currents, bicarbonate invariably mediates a depolarizing current under physiological conditions. Intracellular bicarbonate is quickly replenished by cytosolic carbonic anhydrases. Intracellular bicarbonate levels also depend on different bicarbonate transporters expressed by neurons. The expression of these proteins is not only developmentally regulated but also differs between cell types and even subcellular regions. In this review we will summarize current knowledge about the role of some of these transporters for brain development and brain function.

  2. Two independent anion transport systems in rabbit mandibular salivary glands

    DEFF Research Database (Denmark)

    Novak, I; Young, J A

    1986-01-01

    Cholinergically stimulated Cl and HCO3 transport in perfused rabbit mandibular glands has been studied with extracellular anion substitution and administration of transport inhibitors. In glands perfused with HCO3-free solutions, replacement of Cl with other anions supported secretion in the foll......Cholinergically stimulated Cl and HCO3 transport in perfused rabbit mandibular glands has been studied with extracellular anion substitution and administration of transport inhibitors. In glands perfused with HCO3-free solutions, replacement of Cl with other anions supported secretion...... stimulated secretion by about 30%, but when infused in addition to furosemide (0.1 mmol/l), it inhibited by about 20%. Amiloride (1.0 mmol/l) caused no inhibition. The results suggest that there are at least three distinct carriers in the rabbit mandibular gland. One is a furosemide-sensitive Na-coupled Cl...

  3. Modelling the transport of carbonic acid anions through anion-exchange membranes

    International Nuclear Information System (INIS)

    Nikonenko, V.; Lebedev, K.; Manzanares, J.A.; Pourcelly, G.

    2003-01-01

    Electrodiffusion of carbonate and bicarbonate anions through anion-exchange membranes (AEM) is described on the basis of the Nernst-Planck equations taking into account coupled hydrolysis reactions in the external diffusion boundary layers (DBLs) and internal pore solution. The model supposes local electroneutrality as well as chemical and thermodynamic equilibrium. The transport is considered in three layers being an anion exchange membrane and two adjoining diffusion layers. A mechanism of competitive transport of HCO 3 - and CO 3 2- anions through the membrane which takes into account Donnan exclusion of H + ions is proposed. It is predicted that the pH of the depleting solution decreases and that of the concentrating solution increases during electrodialysis (ED). Eventual deviations from local electroneutrality and local chemical equilibrium are discussed

  4. Organic anion transporting polypeptide 1B transporters modulate hydroxyurea pharmacokinetics

    Science.gov (United States)

    Lancaster, Cynthia S.; Finkelstein, David; Ware, Russell E.; Sparreboom, Alex

    2013-01-01

    Hydroxyurea is currently the only FDA-approved drug that ameliorates the pathophysiology of sickle cell anemia. Unfortunately, substantial interpatient variability in the pharmacokinetics (PK) of hydroxyurea may result in variation of the drug's efficacy. However, little is known about mechanisms that modulate hydroxyurea PK. Recent in vitro studies identifying hydroxyurea as a substrate for organic anion transporting polypeptide (OATP1B) transporters prompted the current investigation assessing the role of OATP1B transporters in modulating hydroxyurea PK. Using wild-type and Oatp1b knockout (Oatp1b−/−) mice, hydroxyurea PK was analyzed in vivo by measuring [14C]hydroxyurea distribution in plasma, kidney, liver, urine, or the exhaled 14CO2 metabolite. Plasma levels were significantly reduced by 20% in Oatp1b−/− mice compared with wild-type (area under the curve of 38.64 or 48.45 μg·h−1·ml−1, respectively) after oral administration, whereas no difference was observed between groups following intravenous administration. Accumulation in the kidney was significantly decreased by twofold in Oatp1b−/− mice (356.9 vs. 748.1 pmol/g), which correlated with a significant decrease in urinary excretion. Hydroxyurea accumulation in the liver was also decreased (136.6 vs. 107.3 pmol/g in wild-type or Oatp1b−/− mice, respectively) correlating with a decrease in exhaled 14CO2. These findings illustrate that deficiency of Oatp1b transporters alters the absorption, distribution, and elimination of hydroxyurea thus providing the first in vivo evidence that cell membrane transporters may play a significant role in modulating hydroxyurea PK. Future studies to investigate other transporters and their role in hydroxyurea disposition are warranted for understanding the sources of variation in hydroxyurea's PK. PMID:23986199

  5. Drugs interacting with organic anion transporter-1 affect uptake of Tc-99m-mercaptoacetyl-triglycine (MAG3) in the human kidney: Therapeutic drug interaction in Tc-99m-MAG3 diagnosis of renal function and possible application of Tc-99m-MAG3 for drug development

    International Nuclear Information System (INIS)

    Takahara, Noriko; Saga, Tsuneo; Inubushi, Masayuki; Kusuhara, Hiroyuki; Seki, Chie; Ito, Sumito; Oyama, Nobuyuki; Yokoyama, Osamu; Sugiyama, Yuichi; Fujibayashi, Yasuhisa

    2013-01-01

    Introduction: Renal uptake of Tc-99m-MG3 involves organic anion transporter (OAT). Treatment with drugs showing OAT affinity might interfere with renal uptake of Tc-99m-MAG3, leading to misinterpretation in Tc-99m-MAG3. This study was conducted to discuss a possible drug interference with Tc-99m-MAG3 diagnosis on OAT sites. Methods: Renal uptake and plasma clearance of Tc-99m-MAG3 were analyzed in healthy volunteers under control and OAT1 and OAT3 related drug treatment conditions. An in vitro uptake study using OAT1 or OAT3 expressing cells was also conducted. Results: Both PAH and probenecid treatment induced delays in Tc-99m-MAG3 clearance from blood, and reductions in the renal uptake clearance. As a result, the normalized effective renal plasma flow estimated from Tc-99m-MAG3 clearance was significantly underestimated, whereas the glomerular filtration rate estimated from plasma creatinine levels was unchanged. The transport activity of Tc-99m-MAG3 was higher in OAT1-expressing cells than in OAT3-expressing cells. Conclusion: Drugs with OAT1 affinity affect the renal uptake of Tc-99m-MAG3 and blood clearance. This might cause misinterpretation of functional diagnosis of the kidney using Tc-99m-MAG3

  6. Hypouricemic Effects of Armillaria mellea on Hyperuricemic Mice Regulated through OAT1 and CNT2.

    Science.gov (United States)

    Yong, Tianqiao; Chen, Shaodan; Xie, Yizhen; Chen, Diling; Su, Jiyan; Shuai, Ou; Hu, Huiping; Zuo, Dan; Liang, Danling

    2018-03-29

    Ethanol and water extracts of Armillaria mellea were prepared by directly soaking A. mellea in ethanol (AME) at 65[Formula: see text]C, followed by decocting the remains in water (AMW) at 85[Formula: see text]C. Significantly, AME and AMW at 30, 60 and 120[Formula: see text]mg/kg exhibited excellent hypouricemic actions, causing remarkable declines from hyperuricemic control (351[Formula: see text][Formula: see text]mol/L, [Formula: see text]) to 136, 130 and 115[Formula: see text][Formula: see text]mol/L and 250, 188 and 152[Formula: see text][Formula: see text]mol/L in serum uric acid, correspondingly. In contrast to the evident renal toxicity of allopurinol, these preparations showed little impacts. Moreover, they showed some inhibitory effect on XOD (xanthine oxidase) activity. Compared with hyperuricemic control, protein expressions of OAT1 (organic anion transporter 1) were significantly elevated in AME- and AMW-treated mice. The levels of GLUT9 (glucose transporter 9) expression were significantly decreased by AMW. CNT2 (concentrative nucleoside transporter 2), a key target for purine absorption in gastrointestinal tract was involved in this study, and was verified for its innovative role. Both AME and AMW down-regulated CNT2 proteins in the gastrointestinal tract in hyperuricemic mice. As they exhibited considerable inhibitory effects on XOD, we selected XOD as the target for virtual screening by using molecular docking, and four compounds were hit with high ranks. From the analysis, we concluded that hydrogen bond, Pi-Pi and Pi-sigma interactions might play important roles for their orientations and locations in XOD inhibition.

  7. Polyspecific organic anion transporting polypeptides mediate hepatic uptake of amphipathic type II organic cations

    NARCIS (Netherlands)

    van Montfoort, J.E; Hagenbuch, B; Fattinger, K.E; Muller, M; Groothuis, Geny; Meijer, D.K F; Meier, P.J

    1999-01-01

    Hepatic uptake of albumin-bound amphipathic organic cations has been suggested to be mediated by multispecific bile salt and organic anion transport systems. Therefore, we investigated whether the recently cloned rat organic anion transporting polypeptides 1 and 2 as well as the human organic anion

  8. Aspirin and probenecid inhibit organic anion transporter 3-mediated renal uptake of cilostazol and probenecid induces metabolism of cilostazol in the rat.

    Science.gov (United States)

    Wang, Chong; Wang, Changyuan; Liu, Qi; Meng, Qiang; Cang, Jian; Sun, Huijun; Peng, Jinyong; Ma, Xiaochi; Huo, Xiaokui; Liu, Kexin

    2014-06-01

    This study aimed to evaluate the transporter-mediated renal excretion mechanism for cilostazol and to characterize the mechanism of drug-drug interaction (DDI) between cilostazol and aspirin or probenecid. Concentrations of cilostazol and its metabolites OPC-13015 [6-[4-(1-cyclohexyl-1H-tetrazol-5-yl)butoxy]-2(1H)-quinolinone] and OPC-13213 [3,4-dihydro-6-[4-[1-(trans-4-hydroxycyclohexyl)-1H-tetrazol-5-yl]butoxy]-2-(1H)-quinolinone] in rat biologic or cell samples were measured by liquid chromatography-tandem mass spectrometry. Coadministration with probenecid, benzylpenicillin, or aspirin decreased the cumulative urinary excretion of cilostazol and renal clearance. Concentrations of cilostazol and OPC-13213 in plasma decreased, and the concentration of OPC-13015 increased in the presence of probenecid. By contrast, rat plasma cilostazol, in combination with benzylpenicillin or aspirin, sharply increased, and concentrations of OPC-13015 and OPC-13213 did not change. In urine, OPC-13015 was below the level of detection. The cumulative urinary excretion of OPC-13213 decreased in the presence of probenecid, benzylpenicillin, or aspirin. Cilostazol was distributed in the kidney and liver, with tissue to plasma partition coefficient (Kp) values of 8.4 ml/g and 16.3 ml/g, respectively. Probenecid and aspirin reduced cilostazol distribution in the kidney. Probenecid did not affect cilostazol metabolism in the kidney but increased cilostazol metabolism in the liver, and aspirin had no effect on cilostazol metabolism. Benzylpenicillin, aspirin, and cyclo-trans-4-l-hydroxyprolyl-l-serine (JBP485) reduced cilostazol uptake in kidney slices and human organic anion transporter 3 (hOAT3)-human embryonic kidney 293 (HEK293) cells, whereas p-aminohippuric acid did not. Compared with the vector, hOAT3-HEK293 cells accumulated more cilostazol, whereas hOAT1-HEK293 cells did not. OAT3 and Oat3 play a major role in cilostazol renal excretion, whereas OAT1 and Oat1 do not. Oat3 and Cyp

  9. Ternary Complexation on Bacterial Surfaces: Implications for Subsurface Anion Transport

    Science.gov (United States)

    Maclean, L. C.; Higginbottom, C. M.; Fowle, D. A.

    2002-12-01

    The physical, chemical, and biological controls on contaminant mobilities in aquatic ecosystems must be determined to establish the threat that contamination poses to the environment. Quantitative models of contaminant mobilities are required as a prerequisite to guide remediation efforts and to prioritize the potential hazard to the ecosystem of each contaminated site. It is well established that mineral surface adsorption is an important control on contaminant mobilities, and many studies have utilized thermodynamics to quantify metal/organic adsorption in order to yield predictive models of contaminant transport. However, these models of contaminant transport may not be representative of the reactions which control contaminant mobilities as most mineral surfaces are coated with organic acids, bacteria, and extracellular polymers. Numerous laboratory studies have demonstrated that bacterial cell walls have a high affinity for binding metal cations, and field studies indicate that a significant proportion of bacteria cells and associated extracellular matrices are coated with small scale hydrous metal oxides. The small size of bacteria, and in many cases the nanoscale of their associated mineral phases, suggests these bacteria-mineral composites may represent a large proportion of surface area exposed to fluid flow. Therefore, due to the affinity of bacterial cell walls for cations and biominerals, bacteria may also have a significant impact on anionic contaminant mobility in many natural systems. The extent of metal-bacteria adsorption reactions varies drastically as a function of pH and solution chemistry. Current adsorption models have focused on the interactions of positively charged metal cations with bacterial surfaces, however in many oxidizing environments metals such as Cr exist as anions or anionic complexes. We have studied the ability of non-metabolizing cells of the bacterial species Bacillus subtilis and Shewanella putrifaciens to adsorb aqueous Cr

  10. Renal organic anion transport: a comparative and cellular perspective.

    Science.gov (United States)

    Dantzler, William H

    2002-11-13

    A major system for net transepithelial secretion of a wide range of hydrophobic organic anions (OAs) exists in the proximal renal tubules of almost all vertebrates. This process involves transport into the cells against an electrochemical gradient at the basolateral membrane and movement from the cells into the lumen down an electrochemical gradient. Transport into the cells at the basolateral membrane, which is the dominant, rate-limiting step, is a tertiary active transport process, the final step which involves countertransport of the OA into the cells against its electrochemical gradient in exchange for alpha-ketoglutarate moving out of the cells down its electrochemical gradient. The outwardly directed gradient for alpha-ketoglutarate is maintained by metabolism ( approximately 40%) and by transport into the cells across both the basolateral and luminal membranes by separate sodium-dicarboxylate cotransporters ( approximately 60%). The inwardly directed sodium gradient driving alpha-ketoglutarate uptake is maintained by the basolateral Na(+)-K(+)-ATPase, the primary energy-requiring transport step in the total tertiary process. The basolateral OA/alpha-ketoglutarate exchange process now appears to be physiologically regulated by several factors in mammalian tubules, including peptide hormones (e.g., bradykinin) and the autonomic nervous system acting via protein kinase C (PKC) pathways and epidermal growth factor (EGF) working via the mitogen-activated protein kinase (MAPK) pathway.

  11. Regulation of renal peripheral benzodiazepine receptors by anion transport inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Basile, A.S.; Lueddens, W.M.; Skolnick, P.

    1988-01-01

    The in vitro and in vivo regulation of (/sup 3/H)Ro 5-4864 binding to peripheral benzodiazepine receptors (PBR) by ion transport/exchange inhibitors was studied in the kidney. The potencies of 9-anthroic acid, furosemide, bumetanide, hydrochlorothiazide and SITS as inhibitors of (/sup 3/H)Ro 5-4864 binding to renal membranes were consistent with their actions as anion transport inhibitors (Ki approx. = 30 - 130 ..mu..M). In contrast, spironolactone, amiloride, acetazolamide, and ouabain were less potent (Ki=100-1000 ..mu..M). Administration of furosemide to rats for five days resulted in a profound diuresis accompanied by a significant increase in PBR density (43%) that was apparent by the fifth day of treatment. Administration of hydrochlorothiazide or Ro 5-4864 for five days also caused diuresis and increased renal PBR density. Both the diuresis and increased density of PBR produced by Ro 5-4864 were blocked by coadministration of PK 11195, which alone had no effect on either PBR density or urine volume. The equilibrium binding constants of (/sup 3/H)Ro 5-4864 to cardiac membranes were unaffected by administration of any of these drugs. These findings suggest that renal PBR may be selectively modulated in vivo and in vitro by administration of ion transport/exchange inhibitors. 36 references, 4 tables.

  12. Synthetic ion transporters can induce apoptosis by facilitating chloride anion transport into cells.

    Science.gov (United States)

    Ko, Sung-Kyun; Kim, Sung Kuk; Share, Andrew; Lynch, Vincent M; Park, Jinhong; Namkung, Wan; Van Rossom, Wim; Busschaert, Nathalie; Gale, Philip A; Sessler, Jonathan L; Shin, Injae

    2014-10-01

    Anion transporters based on small molecules have received attention as therapeutic agents because of their potential to disrupt cellular ion homeostasis. However, a direct correlation between a change in cellular chloride anion concentration and cytotoxicity has not been established for synthetic ion carriers. Here we show that two pyridine diamide-strapped calix[4]pyrroles induce coupled chloride anion and sodium cation transport in both liposomal models and cells, and promote cell death by increasing intracellular chloride and sodium ion concentrations. Removing either ion from the extracellular media or blocking natural sodium channels with amiloride prevents this effect. Cell experiments show that the ion transporters induce the sodium chloride influx, which leads to an increased concentration of reactive oxygen species, release of cytochrome c from the mitochondria and apoptosis via caspase activation. However, they do not activate the caspase-independent apoptotic pathway associated with the apoptosis-inducing factor. Ion transporters, therefore, represent an attractive approach for regulating cellular processes that are normally controlled tightly by homeostasis.

  13. Modulatory effects of hormones, drugs, and toxic events on renal organic anion transport.

    NARCIS (Netherlands)

    Terlouw, S.A.; Masereeuw, R.; Russel, F.G.M.

    2003-01-01

    The human body is exposed continuously to a wide variety of exogenous compounds, many of which are anionic compounds. In addition, products of phase II biotransformation reactions are negatively charged, viz. glucuronides, sulfate esters, or glutathiones. Renal transport of organic anions is an

  14. The role of the canalicular multispecific organic anion transporter in the disposal of endo- and xenobiotics

    NARCIS (Netherlands)

    Oude Elferink, R. P.; Jansen, P. L.

    1994-01-01

    Bile is an important excretory route for the elimination of amphiphilic organic anions, and hepatocytes are the primary secretory units of bile formation. The hepatocytic basolateral and canalicular membranes are equipped with various carrier proteins. Transport across the canalicular membrane

  15. THE ROLE OF THE CANALICULAR MULTISPECIFIC ORGANIC ANION TRANSPORTER IN THE DISPOSAL OF ENDOBIOTICS AND XENOBIOTICS

    NARCIS (Netherlands)

    ELFERINK, RPJO; JANSEN, PLM

    1994-01-01

    Bile is an important excretory route for the elimination of amphiphilic organic anions, and hepatocytes are the primary secretory units of bile formation. The hepatocytic basolateral and canalicular membranes are equipped with various carrier proteins. Transport across the canalicular membrane

  16. Improvement of Anion Transport Systems by Modulation of Chalcogen Interactions: The influence of solvent.

    Science.gov (United States)

    Sánchez-Sanz, Goar; Trujillo, Cristina

    2018-02-08

    A series of potential anion transporters, dithieno[3,2-b;2',3'-d]thiophenes (DTT), involving anion-chalcogen interactions have been studied by analyzing the interaction energy, geometry, and charge transfer. It was found that gas phase calculations show very negative interaction energies with short anion-chalcogen distances, but when solvent effects are considered, the interaction energy values decreased drastically concomitantly with an elongation on the interatomic distances. To enhance the chalcogen interaction between the DTT derivatives and the anion, increasing the anion transporter capacity, bisisothioazole moiety was considered; i.e., the σ-hole of the chalcogen atom was modulated by substitution of the adjacent carbon by a nitrogen atom in the S-C axis, increasing the depth of the σ-hole and therefore the interaction between the chalcogen and anion. Finally, different anions were analyzed within the complexes, finding that F - and NO 3 - would be the best candidates to form complexes and possibly displace other anions such as Cl - or Br - .

  17. Organic anion transporter (Slc22a) family members as mediators of toxicity

    International Nuclear Information System (INIS)

    Sweet, Douglas H.

    2005-01-01

    Exposure of the body to toxic organic anions is unavoidable and occurs from both intentional and unintentional sources. Many hormones, neurotransmitters, and waste products of cellular metabolism, or their metabolites, are organic anions. The same is true for a wide variety of medications, herbicides, pesticides, plant and animal toxins, and industrial chemicals and solvents. Rapid and efficient elimination of these substances is often the body's best defense for limiting both systemic exposure and the duration of their pharmacological or toxicological effects. For organic anions, active transepithelial transport across the renal proximal tubule followed by elimination via the urine is a major pathway in this detoxification process. Accordingly, a large number of organic anion transport proteins belonging to several different gene families have been identified and found to be expressed in the proximal nephron. The function of these transporters, in combination with the high volume of renal blood flow, predisposes the kidney to increased toxic susceptibility. Understanding how the kidney mediates the transport of organic anions is integral to achieving desired therapeutic outcomes in response to drug interactions and chemical exposures, to understanding the progression of some disease states, and to predicting the influence of genetic variation upon these processes. This review will focus on the organic anion transporter (OAT) family and discuss the known members, their mechanisms of action, subcellular localization, and current evidence implicating their function as a determinant of the toxicity of certain endogenous and xenobiotic agents

  18. Organic anion transporting polypeptide 2 transports valproic acid in rat brain microvascular endothelial cells.

    Science.gov (United States)

    Guo, Yi; Jiang, Li

    2016-07-01

    Abnormal drug transporter expression or function in the brain may lead to decreased concentrations of antiepileptic drugs (AEDs) in the central nervous system in patients with drug-resistant epilepsy. We previously showed the influx transporter organic anion transport polypeptide 2 (Oatp2) was expressed in rat brain microvascular endothelial cells (BMECs). Seizures decrease expression of Oatp2, but it remains unclear whether Oatp2 transports AEDs. In this study, we utilized rat BMECs as an in vitro model of the blood-brain barrier (BBB) to study Oatp2-mediated transport of valproic acid (VPA), the most common clinically used AEDs. In vivo injection of pregnenolone-16-carbonitrile was used to induce high expression of Oatp2 in isolated BMECs. Small interfering RNA treatment was used to silence Oatp2, and uptake of VPA was assessed. Increased expression of Oatp2 in BMECs increased the uptake of VPA, while inhibition of Oatp2 reduced VPA uptake. This study indicates Oatp2 transports VPA across the BBB, and suggests altered Oatp2 expression may contribute to resistance to VPA in patients with drug-resistant epilepsy.

  19. Organic anion transporter 2 (SLC22A7) is a facilitative transporter of cGMP.

    Science.gov (United States)

    Cropp, Cheryl D; Komori, Takafumi; Shima, James E; Urban, Thomas J; Yee, Sook Wah; More, Swati S; Giacomini, Kathleen M

    2008-04-01

    The second messenger, cGMP, mediates a host of cellular responses to various stimuli, resulting in the regulation of many critical physiologic functions. The existence of specific cGMP transporters on the plasma membrane that participate in the regulation of cGMP levels has been suggested in a large number of studies. In this study, we identified a novel plasma membrane transporter for cGMP. In particular, we showed that hOAT2 (SLC22A7), a member of the solute carrier (SLC) superfamily, was a facilitative transporter for cGMP and other guanine nucleotides. hOAT2, which is ubiquitously expressed at high levels in many cell types, was previously thought to primarily transport organic anions. Among purine and pyrimidine nucleobases, nucleosides, and nucleotides, hOAT2 showed the greatest preference for cGMP, which transported cGMP with a K(m) value of 88 +/- 11 muM and exhibited between 50- and 100-fold enhanced uptake over control cells. Our data revealed that hOAT2 is a bidirectional facilitative transporter that can control both intracellular and extracellular levels of cGMP. In addition, we observed that a common alternatively spliced variant of hOAT2 demonstrated a complete loss of transport function as a result of a low expression level on the plasma membrane. We conclude that hOAT2 is a highly efficient, facilitative transporter of cGMP and may be involved in cGMP signaling in many tissues. Our study suggests that hOAT2 represents a potential new drug target for regulating cGMP levels.

  20. Interactions between organic anions on multiple transporters in Caco-2 cells

    DEFF Research Database (Denmark)

    Grandvuinet, Anne Sophie; Steffansen, Bente

    2011-01-01

    Caco-2 cell line may be used as an overall model to predict interactions on multiple membrane transporters in the intestine. Taurocholic acid (TCA) and estrone-3-sulfate (E1S) were used as model substrates. Possible inhibitors studied were TCA, E1S, taurolithocholic acid, fluvastatin, and glipizide......-dependent bile acid transporter and the organic solute transporter α/β, and to less extent by the organic anion transporting polypeptide 2B1. However, interactions on efflux transporters were not detected, although they were expected from the literature on the investigated compounds. Biosimulation methods may...

  1. Polyspecific drug and steroid clearance by an organic anion transporter of mammalian liver

    NARCIS (Netherlands)

    Bossuyt, [No Value; Muller, M; Hagenbuch, B; Meier, PJ

    An organic anion-transporting polypeptide that mediates sodium-independent uptake of negatively charged sulfobromophthalein and bile salts has recently been cloned from rat liver (Jacquemin et al., 1994). In this study we have extended the substrate specificity studies to neutral and positively

  2. Enhanced Anion Transport Using Some Expanded Porphyrins as Carriers.

    Science.gov (United States)

    1991-01-01

    many others who provided me with invaluable and much needed help. Miguel Rosingana, Kevin Boudreaux, Micheal Cyr, Dr. Tony Burrell, and Kevin Shredder ...channel in erythrocytes; and the so-called ATP/ADP exchanger. 19 A breakdown in the mediated transport of an essential metabolqtes can be detrimental. For

  3. The role of organic anion transporters in diagnosing liver diseases by magnetic resonance imaging.

    Science.gov (United States)

    Pastor, Catherine M; Müllhaupt, Beat; Stieger, Bruno

    2014-04-01

    The expression and transport functions of organic anion transporters are modified in liver diseases, and therefore the vascular clearances of endogenous and exogenous organic anions that are taken up by these transporters have been used to assess liver diseases in patients. More recently, liver imaging with hepatobiliary contrast agents, tracers, and dyes that cross hepatocytes through the organic anion transporting polypeptides (OATPs)-multidrug resistance-associated proteins (MRPs) pathway were developed to detect and characterize focal lesions and to assess the severity of diffuse liver diseases. This review focuses mainly on magnetic resonance imaging and highlights the growing interest in imaging the OATPs-MRP2 pathway to better understand liver diseases. Imaging provides noninvasive measurements of tissue concentrations that result from the interplay between influx and efflux membrane transport systems in normal or injured hepatocytes. Imaging with magnetic resonance hepatobiliary contrast agents improves the detection and the characterization of hepatic focal lesions. New developments of imaging to assess liver function and understand the hepatocellular concentrations of contrast agents are discussed.

  4. Effect of probenecid on the transport of methyl mercury in erythrocytes by the organic anion transport system

    Energy Technology Data Exchange (ETDEWEB)

    Wu Guang [Biochemistry Section, National Institute for Minamata Disease, Minamata, Kumamoto (Japan)

    1997-02-01

    The uptake of methyl mercury (MeHg) by isolated erythrocytes from rats was studied at 5 and 20 C. The Na{sup +} ion was used to examine exerted effects of probenecid on the uptake of MeHg through the organic anion transport system. Different extracellular pH levels were used to examine effects on the uptake of MeHg and on probenecid induced effects on the uptake of MeHg through the organic anion transport system; the effects of three anisotonic conditions were also determined. The results showed: (1) probenecid might partially change the role of Na{sup +} ion from inhibition to stimulation for the uptake of MeHg; (2) the organic anion transport system for the uptake of MeHg was pH-dependent within the physiological range of extracellular pH; (3) the organic transport system for the uptake of MeHg was independent of deformation of the erythrocyte membrane. (orig.). With 4 figs.

  5. Influence of anisotropy, anion sorption, and degree of decomposition on solute transport in peat

    Science.gov (United States)

    McCarter, C. P. R.; Rezanezhad, F.; Gharedaghloo, B.; Price, J. S.; Van Cappellen, P.

    2017-12-01

    Many permafrost regions are covered by peat dominated wetlands that govern the flow of water, nutrients, and contaminants in these landscapes. However, due to the non-linear decrease in active pore distribution, hydraulic conductivity, and anisotropy with depth from surface, solute transport processes in peat and peatlands are complex and generally poorly understood. Historically, the majority of solute transport studies in peat and peatlands rely on non-reactive chemical tracers (e.g., chloride or bromide) but the high organic content of peat creates the potential for anion sorption. Where anion sorption is possible, the conservative nature of non-reactive anion tracers may be questionable; however, conservative isotopic tracers, such as deuterated water, present the opportunity to determine whether "non-reactive" anions are truly conservative in highly organic peat soils. Given these critical gaps in our understanding, this study aims to characterize the influence of pore structure, anisotropy, and diffusion on the transport of chloride and deuterium tracers at two depths below the surface (-20 and -70 cm); representing two distinct levels of peat decomposition. The results indicate that the chloride sorption partitioning coefficient decreased with degree of decomposition, yet all levels of decomposition showed limited sorption at low concentrations (< 165 mg/L); suggesting a partial conservative behaviour of chloride in peat. However, chloride was sorbed at higher concentrations; thus, limiting its effectiveness as a conservative tracer. Horizontal dispersivity was higher than vertical at both -20 and -70 cm depths and, on average, dispersivity increased with depth suggesting a more tortuous flow path at lower depths. These results highlight that unlike hydraulic conductivity, which is typically larger horizontally than vertically, the majority of solute transport may occur in a subset of pores the hydraulically active pores.

  6. The inhibitory effects of five alkaloids on the substrate transport mediated through human organic anion and cation transporters.

    Science.gov (United States)

    Shams, Tahiatul; Lu, Xiaoxi; Zhu, Ling; Zhou, Fanfan

    2018-02-01

    1. Human solute carrier transporters (SLCs) are important membrane proteins mediate the cellular transport of many endogenous and exogenous substances. Organic anion/cation transporters (OATs/OCTs) and organic anion transporting polypeptides (OATPs) are essential SLCs involved in drug influx. Drug-drug/herb interactions through competing for specific SLCs often lead to unsatisfied therapeutic outcomes and/or unwanted side effects. In this study, we comprehensively investigated the inhibitory effects of five clinically relevant alkaloids (dendrobine, matrine, oxymatrine, tryptanthrin and chelerythrine) on the substrate transport through several OATs/OCTs and OATPs. 2. We performed transport functional assay and kinetic analysis on the HEK-293 cells over-expressing each SLC gene. 3. Our data showed tryptanthrin significantly inhibited the transport activity of OAT3 (IC 50  = 0.93 ± 0.22 μM, K i  = 0.43 μM); chelerythrine acted as a potent inhibitor to the substrate transport mediated through OATP1A2 (IC 50  = 0.63 ± 0.43 μM, K i  = 0.60 μM), OCT1 (IC 50  = 13.60 ± 2.81 μM) and OCT2 (IC 50  =10.80 ± 1.16 μM). 4. Our study suggested tryptanthrin and chelerythrine could potently impact on the drug transport via specific OATs/OCTs. Therefore, the co-administration of these alkaloids with drugs could have clinical consequences due to drug-drug/herb interactions. Precautions should be warranted in the multi-drug therapies involving these alkaloids.

  7. Anion complexation and transport by isophthalamide and dipicolinamide derivatives: DNA plasmid transformation in E. coli.

    Science.gov (United States)

    Atkins, Jason L; Patel, Mohit B; Daschbach, Megan M; Meisel, Joseph W; Gokel, George W

    2012-08-22

    Tris-arenes based on either isophthalic acid or 2,6-dipicolinic acid have been known for more than a decade to bind anions. Recent studies have also demonstrated their ability to transport various ions through membranes. In this report, we demonstrate two important properties of these simple diamides. First, they transport plasmid DNA into Escherichia coli about 2-fold over controls, where the ampicillin resistance gene is expressed in the bacteria. These studies were done with plasmid DNA (~2.6 kilobase (kb)) in JM109 E. coli cells. Second, known methods do not typically transport large plasmids (>15 kb). We demonstrate here that transformation of large pVIB plasmids (i.e., >20 kb) were enhanced over water controls by ~10-fold. These results are in striking contrast to the normal decrease in transformation with increasing plasmid size.

  8. Targeting organic anion transporter 3 with probenecid as a novel anti-influenza a virus strategy.

    Science.gov (United States)

    Perwitasari, Olivia; Yan, Xiuzhen; Johnson, Scott; White, Caleb; Brooks, Paula; Tompkins, S Mark; Tripp, Ralph A

    2013-01-01

    Influenza A virus infection is a major global health concern causing significant mortality, morbidity, and economic loss. Antiviral chemotherapeutics that target influenza A virus are available; however, rapid emergence of drug-resistant strains has been reported. Consequently, there is a burgeoning need to identify novel anti-influenza A drugs, particularly those that target host gene products required for virus replication, to reduce the likelihood of drug resistance. In this study, a small interfering RNA (siRNA) screen was performed to identify host druggable gene targets for anti-influenza A virus therapy. The host organic anion transporter-3 gene (OAT3), a member of the SLC22 family of transporters, was validated as being required to support influenza A virus replication. Probenecid, a prototypical uricosuric agent and chemical inhibitor of organic anion transporters known to target OAT3, was shown to be effective in limiting influenza A virus infection in vitro (50% inhibitory concentration [IC(50)] of 5.0 × 10(-5) to 5.0 × 10(-4) μM; P Probenecid is widely used for treatment of gout and related hyperuricemic disorders, has been extensively studied for pharmacokinetics and safety, and represents an excellent candidate for drug repositioning as a novel anti-influenza A chemotherapeutic.

  9. Ammonium Bicarbonate Transport in Anion Exchange Membranes for Salinity Gradient Energy

    KAUST Repository

    Geise, Geoffrey M.

    2013-09-17

    Many salinity gradient energy technologies such as reverse electrodialysis (RED) rely on highly selective anion transport through polymeric anion exchange membranes. While there is considerable interest in using thermolytic solutions such as ammonium bicarbonate (AmB) in RED processes for closed-loop conversion of heat energy to electricity, little is known about membrane performance in this electrolyte. The resistances of two commercially available cation exchange membranes in AmB were lower than their resistances in NaCl. However, the resistances of commercially available anion exchange membranes (AEMs) were much larger in AmB than in NaCl, which would adversely affect energy recovery. The properties of a series of quaternary ammonium-functionalized poly(phenylene oxide) and Radel-based AEMs were therefore examined to understand the reasons for increased resistance in AmB to overcome this performance penalty due to the lower mobility of bicarbonate, 4.59 × 10-4 cm2/(V s), compared to chloride, 7.90 × 10-4 cm2/(V s) (the dilute aqueous solution mobility ratio of HCO3 - to Cl- is 0.58). Most membrane resistances were generally consistent with the dilute solution mobilities of the anions. For a few key samples, however, increased water uptake in AmB solution reduced the ionic resistance of the polymer compared to its resistance in NaCl solution. This increased water uptake was attributed to the greater hydration of the bicarbonate ion compared to the chloride ion. The increased resistance due to the use of bicarbonate as opposed to chloride ions in AEMs can therefore be mitigated by designing polymers that swell more in AmB compared to NaCl solutions, enabling more efficient energy recovery using AmB thermolytic solutions in RED. © 2013 American Chemical Society.

  10. Role of phosphate and other proton-donating anions in respiration-coupled transport of Ca2+ by mitochondria.

    Science.gov (United States)

    Lehninger, A L

    1974-04-01

    Measurements of extra oxygen consumption, (45)Ca(2+) uptake, and the osmotic expansion of the matrix compartment show that not all permeant anions are capable of supporting and accompanying the energy-dependent transport of Ca(2+) from the medium into the matrix in respiring rat-liver mitochondria. Phosphate, arsenate, acetate, butyrate, beta-hydroxybutyrate, lactate, and bicarbonate + CO(2) supported Ca(2+) uptake, whereas the permeant anions, nitrate, thiocyanate, chlorate, and perchlorate, did not. The active anions share a common denominator, the potential ability to donate a proton to the mitochondrial matrix; the inactive anions lack this capacity. Phosphate and the other active permeant anions move into the matrix in response to the alkaline-inside electrochemical gradient of protons generated across the mitochondrial membrane by electron transport, thus forming a negative-inside anion gradient. It is postulated that the latter gradient is the immediate "pulling" force for the influx of Ca(2+) on the electrogenic Ca(2+) carrier in respiring mitochondria under intracellular conditions. Since mitochondria in the cell are normally exposed to an excess of phosphate (and the bicarbonate-CO(2) system), particularly in state 4, inward transport of these proton-yielding anions probably precedes and is necessary for inward transport of Ca(2+) and other cations under biological conditions. These observations indicate that a negative-inside gradient of phosphate generated by electron transport is a common step and provides the immediate motive power not only for (a) the inward transport of dicarboxylates and tricarboxylates and (b) the energy-dependent exchange of external ADP(3-) for internal ATP(4-) during oxidative phosphorylation, as has already been established, but also for (c) the inward transport of Ca(2+), K(+), and other cations.

  11. Preliminary integrated calculation of radionuclide cation and anion transport at Yucca Mountain using a geochemical model

    International Nuclear Information System (INIS)

    Birdsell, K.H.; Campbell, K.; Eggert, K.G.; Travis, B.J.

    1989-01-01

    This paper presents preliminary transport calculations for radionuclide movement at Yucca Mountain using preliminary data for mineral distributions, retardation parameter distributions, and hypothetical recharge scenarios. These calculations are not performance assessments, but are used to study the effectiveness of the geochemical barriers at the site at mechanistic level. The preliminary calculations presented have many shortcomings and should be viewed only as a demonstration of the modeling methodology. The simulations were run with TRACRN, a finite-difference porous flow and radionuclide transport code developed for the Yucca Mountain Project. Approximately 30,000 finite-difference nodes are used to represent the unsaturated and saturated zones underlying the repository in three dimensions. Sorption ratios for the radionuclides modeled are assumed to be functions of mineralogic assemblages of the underlying rock. These transport calculations present a representative radionuclide cation, 135 Cs and anion, 99 Tc. The effects on transport of many of the processes thought to be active at Yucca Mountain may be examined using this approach. The model provides a method for examining the integration of flow scenarios, transport, and retardation processes as currently understood for the site. It will also form the basis for estimates of the sensitivity of transport calculations to retardation processes. 11 refs., 17 figs., 1 tab

  12. Renal Organic Anion Transporters (SLC22 Family): Expression, Regulation, Roles in Toxicity, and Impact on Injury and Disease

    OpenAIRE

    Wang, Li; Sweet, Douglas H.

    2012-01-01

    Organic solute flux across the basolateral and apical membranes of renal proximal tubule cells is a key process for maintaining systemic homeostasis. It represents an important route for the elimination of metabolic waste products and xenobiotics, as well as for the reclamation of essential compounds. Members of the organic anion transporter (OAT, SLC22) family expressed in proximal tubules comprise one pathway mediating the active renal secretion and reabsorption of organic anions. Many drug...

  13. Transport of organic anions through the erythrocyte membrane as K+-valinomycin complexes.

    Science.gov (United States)

    Marinetti, G V; Skarin, A; Whitman, P

    1978-04-26

    K+, Rb+, or Cs+ complexes of valinomycin form ion pair complexes with picric acid and trinitrobenzenesulfonate (TNBS). The formation of a picrate-K+-valinomycin complex is supported by spectral evidence. These complexes have zero net charge and readily permeate the intact erythrocyte membrane. The K+-valinomycin complex has been used to convert the nonpenetrating TNBS into a penetrating covalent probe, making it as useful vectorial probe to measure accessible amino groups of proteins and phospholipids on both sites of the erythrocyte membrane. The enhanced transport of TNBS into the cell by valinomycin is dependent on external K+ in the medium. The entry of TNBS into the cell is manifested by an increased labeling of hemoglobin and membrane phosphatidylethanolamine (PE). Stilbeneisothiocyanatedisulfonate (SITS) and anilinonaphthalenesulfonate (ANS) inhibit both the basal and K+-valinomycin stimulated labeling of PE and hemoglobin by TNBS. The data suggest two independent effects of ANS and SITS, one mediated by an inhibition of the anion transport protein and another by the incorporation of these hydrobic anions into the cell membrane with an increase in negative charge on the membrane which leads to an inhibition of TNBS permeation into the cell by electrostatic repulsion.

  14. Structural transition, subgap states, and carrier transport in anion-engineered zinc oxynitride nanocrystalline films

    International Nuclear Information System (INIS)

    Xian, Fenglin; Ye, Jiandong; Gu, Shulin; Tan, Hark Hoe; Jagadish, Chennupati

    2016-01-01

    In this work, anion alloying is engineered in ZnON nanocrystalline films, and the resultant evolution of the structural transition, subgap states, and carrier transport is investigated. A broad distribution of sub-gap states above the valence band maximum is introduced by nitrogen due to the hybridization of N 2p and O 2p orbitals. The phase transition from partially amorphous states to full crystallinity occurs above a characteristic growth temperature of 100 °C, and the localized states are suppressed greatly due to the reduction of nitrogen composition. The electronic properties are dominated by grain boundary scattering and electron transport across boundary barriers through thermal activation at band edge states at high temperatures. The conductivity below 130 K exhibits a weak temperature dependence, which is a signature of variable-range hopping conduction between localized states introduced by nitrogen incorporation.

  15. Structural transition, subgap states, and carrier transport in anion-engineered zinc oxynitride nanocrystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Xian, Fenglin [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra 2601 (Australia); Ye, Jiandong, E-mail: yejd@nju.edu.cn [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra 2601 (Australia); School of Electronics Science and Engineering, Nanjing University, Nanjing 210093 (China); Gu, Shulin [School of Electronics Science and Engineering, Nanjing University, Nanjing 210093 (China); Tan, Hark Hoe; Jagadish, Chennupati [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra 2601 (Australia)

    2016-07-11

    In this work, anion alloying is engineered in ZnON nanocrystalline films, and the resultant evolution of the structural transition, subgap states, and carrier transport is investigated. A broad distribution of sub-gap states above the valence band maximum is introduced by nitrogen due to the hybridization of N 2p and O 2p orbitals. The phase transition from partially amorphous states to full crystallinity occurs above a characteristic growth temperature of 100 °C, and the localized states are suppressed greatly due to the reduction of nitrogen composition. The electronic properties are dominated by grain boundary scattering and electron transport across boundary barriers through thermal activation at band edge states at high temperatures. The conductivity below 130 K exhibits a weak temperature dependence, which is a signature of variable-range hopping conduction between localized states introduced by nitrogen incorporation.

  16. The organic anion transport inhibitor probenecid increases brain concentrations of the NKCC1 inhibitor bumetanide.

    Science.gov (United States)

    Töllner, Kathrin; Brandt, Claudia; Römermann, Kerstin; Löscher, Wolfgang

    2015-01-05

    Bumetanide is increasingly being used for experimental treatment of brain disorders, including neonatal seizures, epilepsy, and autism, because the neuronal Na-K-Cl cotransporter NKCC1, which is inhibited by bumetanide, is implicated in the pathophysiology of such disorders. However, use of bumetanide for treatment of brain disorders is associated with problems, including poor brain penetration and systemic adverse effects such as diuresis, hypokalemic alkalosis, and hearing loss. The poor brain penetration is thought to be related to its high ionization rate and plasma protein binding, which restrict brain entry by passive diffusion, but more recently brain efflux transporters have been involved, too. Multidrug resistance protein 4 (MRP4), organic anion transporter 3 (OAT3) and organic anion transporting polypeptide 2 (OATP2) were suggested to mediate bumetanide brain efflux, but direct proof is lacking. Because MRP4, OAT3, and OATP2 can be inhibited by probenecid, we studied whether this drug alters brain levels of bumetanide in mice. Probenecid (50 mg/kg) significantly increased brain levels of bumetanide up to 3-fold; however, it also increased its plasma levels, so that the brain:plasma ratio (~0.015-0.02) was not altered. Probenecid markedly increased the plasma half-life of bumetanide, indicating reduced elimination of bumetanide most likely by inhibition of OAT-mediated transport of bumetanide in the kidney. However, the diuretic activity of bumetanide was not reduced by probenecid. In conclusion, our study demonstrates that the clinically available drug probenecid can be used to increase brain levels of bumetanide and decrease its elimination, which could have therapeutic potential in the treatment of brain disorders. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Genetics or environment in drug transport: the case of organic anion transporting polypeptides and adverse drug reactions.

    Science.gov (United States)

    Clarke, John D; Cherrington, Nathan J

    2012-03-01

    Organic anion transporting polypeptide (OATP) uptake transporters are important for the disposition of many drugs and perturbed OATP activity can contribute to adverse drug reactions (ADRs). It is well documented that both genetic and environmental factors can alter OATP expression and activity. Genetic factors include single nucleotide polymorphisms (SNPs) that change OATP activity and epigenetic regulation that modify OATP expression levels. SNPs in OATPs contribute to ADRs. Environmental factors include the pharmacological context of drug-drug interactions and the physiological context of liver diseases. Liver diseases such as non-alcoholic fatty liver disease, cholestasis and hepatocellular carcinoma change the expression of multiple OATP isoforms. The role of liver diseases in the occurrence of ADRs is unknown. This article covers the roles OATPs play in ADRs when considered in the context of genetic or environmental factors. The reader will gain a greater appreciation for the current evidence regarding the salience and importance of each factor in OATP-mediated ADRs. A SNP in a single OATP transporter can cause changes in drug pharmacokinetics and contribute to ADRs but, because of overlap in substrate specificities, there is potential for compensatory transport by other OATP isoforms. By contrast, the expression of multiple OATP isoforms is decreased in liver diseases, reducing compensatory transport and thereby increasing the probability of ADRs. To date, most research has focused on the genetic factors in OATP-mediated ADRs while the impact of environmental factors has largely been ignored.

  18. Uptake of perfluorooctanoic acid by Caco-2 cells: Involvement of organic anion transporting polypeptides.

    Science.gov (United States)

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

    2017-08-05

    The mechanism underlying the intestinal absorption of perfluorooctanoic acid (PFOA) was investigated using Caco-2 cells. The uptake of PFOA from the apical membrane of Caco-2 cells was fast, and pH, temperature, and concentration dependent, but Na + independent. Coincubation with sulfobromophthalein (BSP), glibenclamide, estron-3-sulfate, cyclosporine A or rifamycin SV, which are typical substrates or inhibitors of organic anion transporting polypeptides (OATPs), significantly decreased the uptake of PFOA. However, coincubation with probenecid or p-aminohippuric acid, typical substrates of organic anion transporters, did not decrease the uptake of PFOA. Furthermore, coincubation with l-lactic acid or benzoic acid, substrates of monocarboxylic acid transporters, did not decrease PFOA uptake. The relationship between the initial uptake of PFOA and its concentration was saturable, suggesting the involvement of a carrier-mediated process. The calculated K m and uptake clearance (V max /K m ) values for PFOA were 8.3μM and 55.0μL/mg protein/min, respectively. This clearance value was about 3-fold greater than that of the non-saturable uptake clearance (K d : 18.1μL/mg protein/min). Lineweaver-Burk plots revealed that BSP competitively inhibits the uptake of PFOA, with a K i value of 23.1μM. These results suggest that the uptake of PFOA from the apical membranes of Caco-2 cells could be, at least in part, mediated by OATPs along with BSP. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Regorafenib is transported by the organic anion transporter 1B1 and the multidrug resistance protein 2.

    Science.gov (United States)

    Ohya, Hiroki; Shibayama, Yoshihiko; Ogura, Jiro; Narumi, Katsuya; Kobayashi, Masaki; Iseki, Ken

    2015-01-01

    Regorafenib is a small molecule inhibitor of tyrosine kinases, and has been shown to improve the outcomes of patients with advanced colorectal cancer and advanced gastrointestinal stromal tumors. The transport profiles of regorafenib by various transporters were evaluated. HEK293/organic anion transporting polypeptide 1B1 (OATP1B1) cells exhibited increased drug sensitivity to regorafenib. Regorafenib inhibited the uptake of 3H-estrone sulfate by HEK293/OATP1B1 cells in a dose-dependent manner, but did not affect its elimination by P-glycoproteins. The concentration of regorafenib was significantly lower in LLC-PK1/multidrug resistance protein 2 (MRP2) cells than in LLC-PK1 cells treated with the MRP2 inhibitor, MK571. MK571 abolished the inhibitory effects of regorafenib on intracellular accumulation in LLC-PK1/MRP2 cells. The uptake of regorafenib was significantly higher in HEK293/OATP1B1 cells than in OATP1B1-mock cells. Transport kinetics values were estimated to be Km=15.9 µM and Vmax=1.24 nmol/mg/min. No significant difference was observed in regorafenib concentrations between HEK293/OATP1B3 and OATP1B3-mock cells. These results indicated that regorafenib is a substrate for MRP2 and OATP1B1, and also suggest that the substrate preference of regorafenib may implicate the pharmacokinetic profiles of regorafenib.

  20. Glial and Neuronal Glutamate Transporters Differ in the Na+ Requirements for Activation of the Substrate-Independent Anion Conductance

    Directory of Open Access Journals (Sweden)

    Christopher B. Divito

    2017-05-01

    Full Text Available Excitatory amino acid transporters (EAATs are secondary active transporters of L-glutamate and L- or D-aspartate. These carriers also mediate a thermodynamically uncoupled anion conductance that is gated by Na+ and substrate binding. The activation of the anion channel by binding of Na+ alone, however, has only been demonstrated for mammalian EAAC1 (EAAT3 and EAAT4. To date, no difference has been observed for the substrate dependence of anion channel gating between the glial, EAAT1 and EAAT2, and the neuronal isoforms EAAT3, EAAT4 and EAAT5. Here we describe a difference in the Na+-dependence of anion channel gating between glial and neuronal isoforms. Chloride flux through transporters without glutamate binding has previously been described as substrate-independent or “leak” channel activity. Choline or N-methyl-D-glucamine replacement of external Na+ ions significantly reduced or abolished substrate-independent EAAT channel activity in EAAT3 and EAAT4 yet has no effect on EAAT1 or EAAT2. The interaction of Na+ with the neuronal carrier isoforms was concentration dependent, consistent with previous data. The presence of substrate and Na+-independent open states in the glial EAAT isoforms is a novel finding in the field of EAAT function. Our results reveal an important divergence in anion channel function between glial and neuronal glutamate transporters and highlight new potential roles for the EAAT-associated anion channel activity based on transporter expression and localization in the central nervous system.

  1. Enzymatic methylation of band 3 anion transporter in intact human erythrocytes

    International Nuclear Information System (INIS)

    Lou, L.L.; Clarke, S.

    1987-01-01

    Band 3, the anion transport protein of erythrocyte membranes, is a major methyl-accepting substrate of the intracellular erythrocyte protein carboxyl methyltransferase (S-adenosyl-L-methionine: protein-D-aspartate O-methyltransferase; EC 2.1.1.77). The localization of methylation sites in intact cells by analysis of proteolytic fragments indicated that sites were present in the cytoplasmic N-terminal domain as well as the membranous C-terminal portion of the polypeptide. The amino acid residues that serve as carboxyl methylation sites of the erythrocyte anion transporter were also investigated. 3 H-Methylated band 3 was purified from intact erythrocytes incubated with L-[methyl- 3 H]methionine and from trypsinized and lysed erythrocytes incubated with S-adenosyl-L-[methyl- 3 H]methionine. After proteolytic digestion with carboxypeptidase Y, D-aspartic acid beta-[ 3 H]methyl ester was isolated in low yields (9% and 1%, respectively) from each preparation. The bulk of the radioactivity was recovered as [ 3 H]methanol, and the amino acid residue(s) originally associated with these methyl groups could not be determined. No L-aspartic acid beta-[ 3 H]methyl ester or glutamyl gamma-[ 3 H]methyl ester was detected. The formation of D-aspartic acid beta-[ 3 H]methyl esters in this protein in intact cells resulted from protein carboxyl methyltransferase activity since it was inhibited by adenosine and homocysteine thiolactone, which increases the intracellular concentration of the potent product inhibitor S-adenosylhomocysteine, and cycloleucine, which prevents the formation of the substrate S-adenosyl-L-[methyl- 3 H]methionine

  2. The importance of OH − transport through anion exchange membrane in microbial electrolysis cells

    KAUST Repository

    Ye, Yaoli

    2018-01-11

    In two-chamber microbial electrolysis cells (MECs) with anion exchange membranes (AEMs), a phosphate buffer solution (PBS) is typically used to avoid increases in catholyte pH as Nernst equation calculations indicate that high pHs adversely impact electrochemical performance. However, ion transport between the chambers will also impact performance, which is a factor not included in those calculations. To separate the impacts of pH and ion transport on MEC performance, a high molecular weight polymer buffer (PoB), which was retained in the catholyte due to its low AEM transport and cationic charge, was compared to PBS in MECs and abiotic electrochemical half cells (EHCs). In MECs, catholyte pH control was less important than ion transport. MEC tests using the PoB catholyte, which had a higher buffer capacity and thus maintained a lower catholye pH (<8), resulted in a 50% lower hydrogen production rate (HPR) than that obtained using PBS (HPR = 0.7 m3-H2 m−3 d−1) where the catholyte rapidly increased to pH = 12. The main reason for the decreased performance using PoB was a lack of hydroxide ion transfer into the anolyte to balance pH. The anolyte pH in MECs rapidly decreased to 5.8 due to a lack of hydroxide ion transport, which inhibited current generation by the anode, whereas the pH was maintained at 6.8 using PBS. In abiotic tests in ECHs, where the cathode potential was set at −1.2 V, the HPR was 133% higher using PoB than PBS due to catholyte pH control, as the anolyte pH was not a factor in the performance. These results show that maintaining charge transfer to control anolyte pH is more important than obtaining a more neutral pH catholyte.

  3. Epigenetic regulation of organic anion transporting polypeptide 1B3 in cancer cell lines.

    Science.gov (United States)

    Imai, Satoki; Kikuchi, Ryota; Tsuruya, Yuri; Naoi, Sotaro; Nishida, Sho; Kusuhara, Hiroyuki; Sugiyama, Yuichi

    2013-11-01

    The expression of a multispecific organic anion transporter, OATP1B3/SLCO1B3, is associated with clinical prognosis and survival of cancer cells. The aims of present study were to investigate the involvement of epigenetic regulation in mRNA expression of a cancer-type variant of OATP1B3 (Ct-OATP1B3) in cancer cell lines. The membrane localization and transport functions of Ct-OATP1B3 were investigated in HEK293 cells transiently expressing Ct-OATP1B3. DNA methylation profiles around the transcriptional start site of Ct-OATP1B3 in cancer cell lines were determined. The effects of a DNA methyltransferase inhibitor and siRNA knockdown of methyl-DNA binding proteins (MBDs) on the expression of Ct-OATP1B3 mRNA were investigated. 5'-RACE identified the TSS of Ct-OATP1B3 in PK-8 cells. Ct-OATP1B3 was localized on the plasma membrane, and showed the transport activities of E217βG, fluvastatin, rifampicin, and Gd-EOB-DTPA. The CpG dinucleotides were hypomethylated in Ct-OATP1B3-positive cell lines (DLD-1, TFK-1, PK-8, and PK-45P) but were hypermethylated in Ct-OATP1B3-negative cell lines (HepG2 and Caco-2). Treatment with a DNA methyltransferase inhibitor and siRNA knockdown of MBD2 significantly increased the expression of Ct-OATP1B3 mRNA in HepG2 and Caco-2. Ct-OATP1B3 is capable of transporting its substrates into cancer cells. Its mRNA expression is regulated by DNA methylation-dependent gene silencing involving MBD2.

  4. Endogenous metabolites that are substrates of organic anion transporter's (OATs) predict methotrexate clearance.

    Science.gov (United States)

    Muhrez, Kienana; Benz-de Bretagne, Isabelle; Nadal-Desbarats, Lydie; Blasco, Hélène; Gyan, Emmanuel; Choquet, Sylvain; Montigny, Frédéric; Emond, Patrick; Barin-Le Guellec, Chantal

    2017-04-01

    Variable pharmacokinetics of high-dose-methotrexate (MTX) is responsible for severe toxicities. Unpredictable overexposure still occurs during some courses despite having controlled the main factors known to play a role in its elimination. The aim of our study was to evaluate whether the urine metabolomic profile measured at the time of MTX administration is predictive of the drug's clearance and/or of treatment-related toxicity. We analyzed the urine content of endogenous metabolites before MTX administration in a cohort of adult patients treated for lymphoid malignancies. Individual MTX clearance (MTX CL ) was estimated from population pharmacokinetic analyses of therapeutic drug monitoring data. We determined the urine metabolite content by gas chromatography-mass spectrometry (GC-MS) and applied Partial Least Square (PLS) analysis to assess the relationship between the urine metabolome and MTX CL . External validation was applied to evaluate the performances of the PLS model. We used orthogonal partial least squares discriminant analysis (OPLS-DA) to distinguish patients with normal or delayed elimination, and patients with or without toxicity. Sixty-two patients were studied. We obtained a very good prediction of individual MTX clearance using a set of 28 metabolites present in patient urine at baseline. The mean prediction error and precision were -0.36% and 21.4%, respectively, for patients not included in the model. The model included a set of endogenous organic anions, of which the tubular secretion depends on organic anion transporter (OAT) function. Our analyses did not allow us to discriminate between patients with or without delayed elimination or those who did or did not experience toxicity. Urinary metabolomics can be informative about an individual's ability to clear MTX. More broadly, it paves the way for the development of a biomarker of tubular secretion, easily measurable from endogenous substances. Copyright © 2016 Elsevier Ltd. All rights

  5. Organic anion and cation transport in vitro by dog choroid plexus: Effects of neuroleptics and tricyclic antidepressants

    International Nuclear Information System (INIS)

    Barany, E.H.

    1979-01-01

    Dog lateral choroid plexus accumulates the cation 14 C-emepronium and the divalent anion 125 I-iodipamide in vitro. At 10 μM, high potency neuroleptics with a substituted piperazine side chain and also haloperidol depress only the uptake of the cation and even stimulate the uptake of the anion. In contrast, at 1-10μM, the accumulation of both test substances is inhibited by neuroleptics and tricyclic antidepresssants with an aliphatic side chain. Such unspecific effects on seemingly unrelated transport systems at concentrations reached clinically in the CSF might explain some side actions of low potency neuroleptics and antidepressants. (author)

  6. Bidirectional transport of iminodiacetic organic anion analogues between plasma and hepatocyte

    Energy Technology Data Exchange (ETDEWEB)

    Peters, A.M.; Myers, M.J.; Mohammadtaghi, S.; Mubashar, M. [Department of Imaging, Division of Investigative Sciences, Imperial College School of Medicine, London (United Kingdom); Mathie, R.T. [Department of Gastrointestinal Surgery, Division of Surgery, Anaesthetics and Intensive Care, Imperial College School of Medicine, London (United Kingdom)

    1998-07-01

    The kinetics of organic anions are well described and back-diffusion from hepatocyte to plasma is accepted. Although iminodiacetic (IDA) analogues, as organic anions, should also show bidirectional transport between hepatocyte and plasma, this has not been directly demonstrated heretofore. The aim of this study was to directly demonstrate back-diffusion and to quantify it in terms of its fractional rate constant. Kinetics of diethyl IDA were studied in three anaesthetised dogs in which femoral arterial and hepatic venous samples were obtained after injection of tracer into (a) a peripheral vein or (b) hepatic artery or portal vein. Arterial time-concentration curves were also compared between peripheral venous and either hepatic arterial or portal venous injections. Time-activity curves were recorded from regions of interest over the cardiac blood pool and peripheral hepatic parenchyma in 30 patients undergoing routine IDA hepatobiliary imaging with diethyl IDA or mebrofenin and fractional rate constants of clearance of IDA from the hepatocyte compared between compartmental and deconvolution analyses. After peripheral injection in dogs, there was an early arteriovenous concentration gradient across the liver indicating an hepatocyte extraction fraction in the three animals of 0.9, 0.8 and 0.6. The net extraction fraction decreased exponentially over 40 min. Time-concentration curves from hepatic vein and femoral artery were virtually superimposed following intrahepatic injections. Peripheral arterial curves, however, had different shapes according to whether injections were intrahepatic or peripheral, and were consistent with significant back-diffusion. In clinical studies, the blood disappearance curves were fitted as the sum of two exponentials and the liver curves as the difference of two exponentials (with rate constants denoted {alpha}{sub 1}{sup h} and {alpha}{sub 2}{sup h}). Based on compartmental analysis of the blood curves, the sum of the fractional rate

  7. DNA methylation profiles of organic anion transporting polypeptide 1B3 in cancer cell lines.

    Science.gov (United States)

    Ichihara, Sayaka; Kikuchi, Ryota; Kusuhara, Hiroyuki; Imai, Satoki; Maeda, Kazuya; Sugiyama, Yuichi

    2010-03-01

    Multispecific organic anion transporter, OATP1B3/SLCO1B3, is expressed in several cancer cell lines as well as tumor tissues, and its expression sensitizes the cells to some anti-cancer agents. The present study was aimed to characterize the DNA methylation profiles around the transcriptional start site (TSS) of OATP1B3 and correlate them with the mRNA expression in cancer and immortalized cell lines. The mRNA expression and DNA methylation profiles of OATP1B3 were determined by RT-PCR and bisulfite sequencing, respectively. The expression of OATP1B3 mRNA was detected in DLD-1, TFK-1, PK-8, and PK-45P cells, but below the limit of detection in HepG2, Caco-2, and HEK293 cells. Bisulfite sequencing demonstrated that CpG dinucleotides around the TSS are differentially methylated among cell lines and partly associated with the mRNA expression profile of OATP1B3. Furthermore, treatment with 5-aza-2'-deoxycytidine, an inhibitor of DNA methyltransferase, significantly increased the mRNA expression of OATP1B3 in HepG2 and Caco-2 cells by 18- and 14-fold, respectively, but not in DLD-1 and TFK-1 cells. DNA methylation-dependent gene silencing is at least partly involved in the regulation of OATP1B3 expression in cancer/immortalized cell lines.

  8. Hypouricemic Effects of Ganoderma applanatum in Hyperuricemia Mice through OAT1 and GLUT9

    Directory of Open Access Journals (Sweden)

    Tianqiao Yong

    2018-01-01

    Full Text Available Ganoderma applanatum (G. applanatum dispels wind to eliminate dampness and exhibited nephron- and liver-protective effects as noted in Chinese herbal classic literature; it might also affect hyperuricemia. Therefore, we examined the hypouricemia effects and mechanisms underlying G. applanatum on chemical-induced hyperuricemia in mice. Ethanol (GAE and water (GAW extracts were prepared by extracting G. applanatum in ethanol (GAE, followed by bathing the remains in water to yield GAW. GAE and GAW were administered orally at different doses to hyperuricemia mice, while allopurinol and benzbromarone served as positive controls. Both GAE and GAW showed remarkable hypouricemia activities, rendering a substantial decline in the SUA (serum uric acid level in hyperuricemia control (P < 0.01. Moreover, the urine uric acid (UUA levels were enhanced by GAE and GAW. In contrast to the evident renal toxicity of allopurinol, GAE and GAW did not show a distinct renal toxicity. Almost no suppressing effect was observed on the XOD activities. However, compared to the hyperuricemia control, OAT1 was elevated remarkably in mice drugged with GAE and GAW, while GLUT9 was significantly decreased. Similar to benzbromarone, GAE decreased the URAT1 protein levels significantly (P < 0.01, while GAW did not display a similar effect. GAE and GAW downregulated the level of CNT2 proteins in the gastrointestinal tract of hyperuricemia mice. Thus, G. applanatum produced outstanding hypouricemic effects, mediated by renal OAT1, GLUT9, and URAT1 and gastrointestinal CNT2 that might elevate urine uric secretions and decline in the absorption of purine in the gastrointestinal tracts. G. applanatum showed little negative influence on inner organs. By docking screening, four top-ranked compounds were identified that necessitated further investigation.Compounds: potassium oxonate, hypoxanthine, allopurinol, benzbromarone.

  9. Does lipophilicity affect the effectiveness of a transmembrane anion transporter? Insight from squaramido-functionalized bis(choloyl) conjugates.

    Science.gov (United States)

    Li, Zhi; Deng, Li-Qun; Chen, Jin-Xiang; Zhou, Chun-Qiong; Chen, Wen-Hua

    2015-12-28

    Six squaramido-functionalized bis(choloyl) conjugates were synthesized and fully characterized on the basis of NMR ((1)H and (13)C) and ESI MS (LR and HR) data. Their transmembrane anionophoric activity was investigated in detail by means of chloride ion selective electrode technique and pyranine assay. The data indicate that this set of compounds is capable of promoting the transmembrane transport of anions presumably via proton/anion symport and anion exchange processes, and that lipophilicity in terms of clog P from 3.90 to 8.32 affects the apparent ion transport rate in a concentration-dependent fashion. Detailed kinetic analysis on the data obtained from both the chloride efflux and pH discharge experiments reveals that there may exist an optimum clog P range for the intrinsic ion transport rate. However, lipophilicity exhibits little effect on the effectiveness of this set of compounds in terms of either k2/Kdiss or EC50 values.

  10. The drug transporter OAT3 (SLC22A8) and endogenous metabolite communication via the gut-liver-kidney axis.

    Science.gov (United States)

    Bush, Kevin T; Wu, Wei; Lun, Christina; Nigam, Sanjay K

    2017-09-22

    The organic anion transporters OAT1 (SLC22A6) and OAT3 (SLC22A8) have similar substrate specificity for drugs, but it is far from clear whether this holds for endogenous substrates. By analysis of more than 600 metabolites in the Oat3KO (Oat3 knockout) by LC/MS, we demonstrate OAT3 involvement in the movement of gut microbiome products, key metabolites, and signaling molecules, including those flowing through the gut-liver-kidney axis. Major pathways affected included those involved in metabolism of bile acids, flavonoids, nutrients, amino acids (including tryptophan-derivatives that are uremic toxins), and lipids. OAT3 is also critical in elimination of liver-derived phase II metabolites, particularly those undergoing glucuronidation. Analysis of physicochemical features revealed nine distinct metabolite groups; at least one member of most clusters has been previously validated in transport assays. In contrast to drugs interacting with the OATs, endogenous metabolites accumulating in the Oat1KO (Oat1 knockout) versus Oat3KO have distinct differences in their physicochemical properties; they are very different in size, number of rings, hydrophobicity, and molecular complexity. Consistent with the Remote Sensing and Signaling Hypothesis, the data support the importance of the OAT transporters in inter-organ and inter-organismal remote communication via transporter-mediated movement of key metabolites and signaling molecules ( e.g. gut microbiome-to-intestine-to-blood-to-liver-to-kidney-to-urine). We discuss the possibility of an intimate connection between OATs and metabolite sensing and signaling pathways ( e.g. bile acids). Furthermore, the metabolomics and pathway analysis support the view that OAT1 plays a greater role in kidney proximal tubule metabolism and OAT3 appears relatively more important in systemic metabolism, modulating levels of metabolites flowing through intestine, liver, and kidney. © 2017 by The American Society for Biochemistry and Molecular

  11. The organic anion transporter OAT3 enhances the glucosuric effect of the SGLT2 inhibitor empagliflozin.

    Science.gov (United States)

    Fu, Yiling; Breljak, Davorka; Onishi, Akira; Batz, Falk; Patel, Rohit; Huang, Winnie; Song, Panai; Freeman, Brent; Mayoux, Eric; Koepsell, Hermann; Anzai, Naohiko; Nigam, Sanjay K; Sabolić, Ivan; Vallon, Volker

    2018-02-07

    The SGLT2 inhibitor empagliflozin (plasma protein binding ~88%) may reach its target in the brush border of the early proximal tubule by glomerular filtration and tubular secretion. Here we determined whether empagliflozin is secreted by renal tubules, and whether genetic knockout of the basolateral organic anion transporter Oat3 (-/-) affects its tubular secretion or glucosuric effect. Renal clearance studies in wild-type (WT) mice showed that tubular secretion accounted for 50-70% of empagliflozin urinary excretion. Immunostaining indicated that SGLT2 and OAT3 localization partially overlapped in proximal tubule S1 and S2 segments. Glucosuria in metabolic cage studies was reduced in Oat3-/- vs. WT mice for acute empagliflozin doses of 1, 3, and 10mg/kg, whereas 30mg/kg induced similar maximal glucosuria in both genotypes. Chronic application of empagliflozin (~25mg kg-1 day-1) in Oat3-/- mice was associated with lower urinary glucose to creatinine ratios despite maintaining slightly higher blood glucose levels than WT. On a whole kidney level, renal secretion of empagliflozin was largely unchanged in Oat3-/- mice. However, the absence of OAT3 attenuated the influence of empagliflozin on fractional glucose excretion; higher levels of plasma or filtered empagliflozin were needed to induce similar increases in fractional renal glucose excretion. We conclude that empagliflozin is excreted into the urine to similar extent by glomerular filtration and tubular secretion. The latter can occur largely independent of OAT3. However, OAT3 increases the glucosuric effect of empagliflozin, which may relate to the partial overlap of its localization with SGLT2 and OAT3-mediated tubular secretion of empagliflozin in the early proximal tubule.

  12. Recent advances on uric acid transporters

    Science.gov (United States)

    Xu, Liuqing; Shi, Yingfeng; Zhuang, Shougang; Liu, Na

    2017-01-01

    Uric acid is the product of purine metabolism and its increased levels result in hyperuricemia. A number of epidemiological reports link hyperuricemia with multiple disorders, such as kidney diseases, cardiovascular diseases and diabetes. Recent studies also showed that expression and functional changes of urate transporters are associated with hyperuricemia. Uric acid transporters are divided into two categories: urate reabsorption transporters, including urate anion transporter 1 (URAT1), organic anion transporter 4 (OAT4) and glucose transporter 9 (GLUT9), and urate excretion transporetrs, including OAT1, OAT3, urate transporter (UAT), multidrug resistance protein 4 (MRP4/ABCC4), ABCG-2 and sodium-dependent phosphate transport protein. In the kidney, uric acid transporters decrease the reabsorption of urate and increase its secretion. These transporters’ dysfunction would lead to hyperuricemia. As the function of urate transporters is important to control the level of serum uric acid, studies on the functional role of uric acid transporter may provide a new strategy to treat hyperuricemia associated diseases, such as gout, chronic kidney disease, hyperlipidemia, hypertension, coronary heart disease, diabetes and other disorders. This review article summarizes the physiology of urate reabsorption and excretion transporters and highlights the recent advances on their roles in hyperuricemia and various diseases. PMID:29246027

  13. Intestinal transporters for endogenic and pharmaceutical organic anions: The challenges of deriving in-vitro kinetic parameters for the prediction of clinically relevant drug-drug interactions

    DEFF Research Database (Denmark)

    Grandvuinet, Anne Sophie; Vestergaard, Henrik Tang; Rapin, Nicolas

    2012-01-01

    of the apical sodium-dependent bile acid transporter (ASBT), the breast cancer resistance protein (BCRP), the monocarboxylate transporters (MCT) 1, MCT3-5, the multidrug resistance associated proteins (MRP) 1-6, the organic anion transporting polypetides (OATP) 2B1, 1A2, 3A1 and 4A1, and the organic solute...

  14. Renal organic anion transporters (SLC22 family): expression, regulation, roles in toxicity, and impact on injury and disease.

    Science.gov (United States)

    Wang, Li; Sweet, Douglas H

    2013-01-01

    Organic solute flux across the basolateral and apical membranes of renal proximal tubule cells is a key process for maintaining systemic homeostasis. It represents an important route for the elimination of metabolic waste products and xenobiotics, as well as for the reclamation of essential compounds. Members of the organic anion transporter (OAT, SLC22) family expressed in proximal tubules comprise one pathway mediating the active renal secretion and reabsorption of organic anions. Many drugs, pesticides, hormones, heavy metal conjugates, components of phytomedicines, and toxins are OAT substrates. Thus, through transporter activity, the kidney can be a target organ for their beneficial or detrimental effects. Detailed knowledge of the OATs expressed in the kidney, their membrane targeting, substrate specificity, and mechanisms of action is essential to understanding organ function and dysfunction. The intracellular processes controlling OAT expression and function, and that can thus modulate kidney transport capacity, are also critical to this understanding. Such knowledge is also providing insight to new areas such as renal transplant research. This review will provide an overview of the OATs for which transport activity has been demonstrated and expression/function in the kidney observed. Examples establishing a role for renal OATs in drug clearance, food/drug-drug interactions, and renal injury and pathology are presented. An update of the current information regarding the regulation of OAT expression is also provided.

  15. Hypouricemic Effects of Ganoderma applanatum in Hyperuricemia Mice through OAT1 and GLUT9

    Science.gov (United States)

    Yong, Tianqiao; Chen, Shaodan; Xie, Yizhen; Chen, Diling; Su, Jiyan; Shuai, Ou; Jiao, Chunwei; Zuo, Dan

    2018-01-01

    Ganoderma applanatum (G. applanatum) dispels wind to eliminate dampness and exhibited nephron- and liver-protective effects as noted in Chinese herbal classic literature; it might also affect hyperuricemia. Therefore, we examined the hypouricemia effects and mechanisms underlying G. applanatum on chemical-induced hyperuricemia in mice. Ethanol (GAE) and water (GAW) extracts were prepared by extracting G. applanatum in ethanol (GAE), followed by bathing the remains in water to yield GAW. GAE and GAW were administered orally at different doses to hyperuricemia mice, while allopurinol and benzbromarone served as positive controls. Both GAE and GAW showed remarkable hypouricemia activities, rendering a substantial decline in the SUA (serum uric acid) level in hyperuricemia control (P applanatum produced outstanding hypouricemic effects, mediated by renal OAT1, GLUT9, and URAT1 and gastrointestinal CNT2 that might elevate urine uric secretions and decline in the absorption of purine in the gastrointestinal tracts. G. applanatum showed little negative influence on inner organs. By docking screening, four top-ranked compounds were identified that necessitated further investigation. Compounds: potassium oxonate, hypoxanthine, allopurinol, benzbromarone. PMID:29379442

  16. Hypouricemic Effects ofGanoderma applanatumin Hyperuricemia Mice through OAT1 and GLUT9.

    Science.gov (United States)

    Yong, Tianqiao; Chen, Shaodan; Xie, Yizhen; Chen, Diling; Su, Jiyan; Shuai, Ou; Jiao, Chunwei; Zuo, Dan

    2017-01-01

    Ganoderma applanatum ( G. applanatum ) dispels wind to eliminate dampness and exhibited nephron- and liver-protective effects as noted in Chinese herbal classic literature; it might also affect hyperuricemia. Therefore, we examined the hypouricemia effects and mechanisms underlying G. applanatum on chemical-induced hyperuricemia in mice. Ethanol (GAE) and water (GAW) extracts were prepared by extracting G. applanatum in ethanol (GAE), followed by bathing the remains in water to yield GAW. GAE and GAW were administered orally at different doses to hyperuricemia mice, while allopurinol and benzbromarone served as positive controls. Both GAE and GAW showed remarkable hypouricemia activities, rendering a substantial decline in the SUA (serum uric acid) level in hyperuricemia control ( P applanatum produced outstanding hypouricemic effects, mediated by renal OAT1, GLUT9, and URAT1 and gastrointestinal CNT2 that might elevate urine uric secretions and decline in the absorption of purine in the gastrointestinal tracts. G. applanatum showed little negative influence on inner organs. By docking screening, four top-ranked compounds were identified that necessitated further investigation. Compounds: potassium oxonate, hypoxanthine, allopurinol, benzbromarone.

  17. Ion transport resistance in Microbial Electrolysis Cells with anion and cation exchange membranes

    NARCIS (Netherlands)

    Sleutels, T.H.J.A.; Hamelers, H.V.M.; Rozendal, R.A.; Buisman, C.J.N.

    2009-01-01

    Previous studies have shown that Microbial Electrolysis Cells (MECs) perform better when an anion exchange membrane (AEM) than when a cation exchange membrane (CEM) separates the electrode chambers. Here, we have further studied this phenomenon by comparing two analysis methods for

  18. Self-Assembly of Fluorinated Sugar Amino Acid Derived α,γ-Cyclic Peptides into Transmembrane Anion Transport.

    Science.gov (United States)

    Burade, Sachin S; Saha, Tanmoy; Bhuma, Naresh; Kumbhar, Navanath; Kotmale, Amol; Rajamohanan, Pattuparambil R; Gonnade, Rajesh G; Talukdar, Pinaki; Dhavale, Dilip D

    2017-11-03

    Syntheses of fluorinated sugar amino acid derived α,γ-cyclic tetra- and hexapeptides are reported. The IR, NMR, ESI-MS, CD, and molecular modeling studies of cyclic tetra- and hexapeptides showed C 2 and C 3 symmetric flat oval- and triangular-ring shaped β-strand conformations, respectively, which appear to self-assemble into nanotubes. The α,γ-cyclic hexapeptide (EC 50 = 2.14 μM) is found to be a more efficient ion transporter than α,γ-cyclic tetrapeptide (EC 50 = 14.75 μM). The anion selectivity and recognition of α,γ-cyclic hexapeptide with NO 3 - ion is investigated.

  19. Organic anion transporting polypeptide 2B1 and breast cancer resistance protein interact in the transepithelial transport of steroid sulfates in human placenta.

    Science.gov (United States)

    Grube, Markus; Reuther, Sebastian; Meyer Zu Schwabedissen, Henriette; Köck, Kathleen; Draber, Katrin; Ritter, Christoph A; Fusch, Christoph; Jedlitschky, Gabriele; Kroemer, Heyo K

    2007-01-01

    The human placenta has both protective and nurturing functions for the fetal organism. Uptake and elimination of xenobiotics and endogenous substances are facilitated by various transport proteins from the solute carrier (SLC) and ABC families, respectively. A functional interaction of uptake and elimination, which is a prerequisite for vectorial transport across cellular barriers, has not been described for placenta. In this study, we examined expression of organic anion transporter (OAT) 4 (SLC22A11), organic anion transporting polypeptide (OATP) 2B1 (SLCO2B1, OATP-B), and breast cancer resistance protein (BCRP) (ABCG2) in human placenta (n = 71) because all three proteins are involved in transmembranal transfer of estrone 3 sulfate (E3S; metabolic product) and dehydroepiandrosterone sulfate (DHEAS; precursor molecule). On the mRNA level, we found a significant correlation of OATP2B1 and BCRP (R(2) = 0.534; p 0.05). Localization studies confirmed basal expression of OATP2B1 and apical expression of BCRP. To study functional interactions between OATP2B1 and BCRP, we developed a Madin-Darby canine kidney cell model expressing both transport proteins simultaneously (OATP2B1 and BCRP in the basal and apical membrane, respectively). Using this cell model in a transwell system resulted in a significantly increased basal to apical transport of both E3S and DHEAS, when both transporters were expressed with no change of transfer in the apical to basal direction. Taken together, these data show the potential for a functional interaction of OATP2B1 and BCRP in transepithelial transport of steroid sulfates in human placenta.

  20. Functional, structural and phylogenetic analysis of domains underlying the Al-sensitivity of the aluminium-activated malate/anion transporter, TaALMT1

    Science.gov (United States)

    TaALMT1 (Triticum aestivum Aluminum Activated Malate Transporter) is the founding member of a novel gene family of anion transporters (ALMTs) that mediate the efflux of organic acids. A small subgroup of root-localized ALMTs, including TaALMT1, is physiologically associated with in planta aluminum (...

  1. Carbon dioxide transport in molten calcium carbonate occurs through an oxo-Grotthuss mechanism via a pyrocarbonate anion.

    Science.gov (United States)

    Corradini, Dario; Coudert, François-Xavier; Vuilleumier, Rodolphe

    2016-05-01

    The reactivity, speciation and solvation structure of CO2 in carbonate melts are relevant for both the fate of carbon in deep geological formations and for its electroreduction to CO (to be used as fuel) when solvated in a molten carbonate electrolyte. In particular, the high solubility of CO2 in carbonate melts has been tentatively attributed to the formation of the pyrocarbonate anion, C2O5(2-). Here we study, by first-principles molecular dynamics simulations, the behaviour of CO2 in molten calcium carbonate. We find that pyrocarbonate forms spontaneously and the identity of the CO2 molecule is quickly lost through O(2-) exchange. The transport of CO2 in this molten carbonate thus occurs in a fashion similar to the Grotthuss mechanism in water, and is three times faster than molecular diffusion. This shows that Grotthuss-like transport is more general than previously thought.

  2. Up-regulation of the multidrug resistance genes, mrp1 and mdr1b, and down-regulation of the organic anion transporter, Mrp2, and the bile salt transporter, spgp, in endotoxemic rat liver

    NARCIS (Netherlands)

    Vos, TA; Hooiveld, GJEJ; Childs, S; Meijer, DKF; Moshage, H; Jansen, PLM; Muller, M

    1998-01-01

    Endotoxin-induced cholestasis is mainly caused by an impaired canalicular secretion. Mrp2, the canalicular multispecific organic anion transporter, is strongly downregulated in this situation, and canalicular bile salt secretion is also reduced. We hypothesized that other adenosine

  3. Organic anion transporter 2 transcript variant 1 shows broad ligand selectivity when expressed in multiple cell lines.

    Science.gov (United States)

    Hotchkiss, Adam G; Berrigan, Liam; Pelis, Ryan M

    2015-01-01

    Organic anion transporter 2 (OAT2) is likely important for renal and hepatic drug elimination. Three variants of the OAT2 peptide sequence have been described - OAT2 transcript variant 1 (OAT2-tv1), OAT2 transcript variant 2 (OAT2-tv2), and OAT2 transcript variant 3 (OAT2-tv3). Early studies helping to define the ligand selectivity of OAT2 failed to identify the variant used, and the studies used several heterologous expression systems. In preliminary studies using OAT2-tv1, we failed to observe transport of several previously identified substrates, leading us to speculate that ligand selectivity of OAT2 differs with variant and/or heterologous expression system. The purpose was to further investigate the ligand selectivity of the OAT2 variants expressed in multiple cell types. We cloned OAT2-tv1 and OAT2-tv2, but were unsuccessful at amplifying mRNA for OAT2-tv3 from human kidney. OAT2-tv1 and OAT2-tv2 were individually expressed in human embryonic kidney (HEK), Madin-Darby canine kidney (MDCK), or Chinese hamster ovary (CHO) cells. mRNA for OAT2-tv1 and OAT2-tv2 was demonstrated in each cell type transfected with the respective construct, indicating their expression. OAT2-tv1 trafficked to the plasma membrane of all three cell types, but OAT2-tv2 did not. OAT2-tv1 transported penciclovir in all three cell types, but failed to transport para-aminohippurate, succinate, glutarate, estrone-3-sulfate, paclitaxel or dehydroepiandrosterone sulfate - previously identified substrates of OAT2-tv2. Not surprising given its lack of plasma membrane expression, OAT2-tv2 failed to transport any of the organic solutes examined, including penciclovir. Penciclovir transport by OAT2-tv1 was sensitive to large (e.g., cyclosporine A) and small (e.g., allopurinol) organic compounds, as well as organic anions, cations and neutral compounds, highlighting the multiselectivity of OAT2-tv1. The potencies with which indomethacin, furosemide, cyclosporine A and cimetidine inhibited OAT2-tv1

  4. Influence of non-steroidal anti-inflammatory drugs on organic anion transporting polypeptide (OATP) 1B1- and OATP1B3-mediated drug transport.

    Science.gov (United States)

    Kindla, Juergen; Müller, Fabian; Mieth, Maren; Fromm, Martin F; König, Jörg

    2011-06-01

    The transporter-mediated uptake of drugs from blood into hepatocytes is a prerequisite for intrahepatic drug action or intracellular drug metabolism before excretion. Therefore, uptake transporters, e.g., members of the organic anion transporting polypeptide (OATP) family are important determinants of drug pharmacokinetics. Highly and almost exclusively expressed in hepatocytes are the OATP family members OATP1B1 (SLCO1B1) and OATP1B3 (SLCO1B3). Drug substrates of OATP1B1 and OATP1B3 include antibiotics and HMG-CoA reductase inhibitors (statins). It has been demonstrated that administration of two or more drugs that are substrates for these hepatic uptake transporters may lead to transporter-mediated drug-drug interactions, resulting in altered transport kinetics for drug substrates. In this study we investigated whether non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol interact with OATP1B1 and OATP1B3 using the standard substrate BSP and the drug substrate pravastatin. Using human embryonic kidney cells stably expressing OATP1B1 or OATP1B3, we demonstrated that bromosulfophthalein uptake was inhibited by diclofenac, ibuprofen. and lumiracoxib. Of interest, pravastatin uptake was stimulated by these NSAIDs, and for ibuprofen we determined activation constants (EC₅₀ values) of 64.0 and 93.1 μM for OATP1B1- and OATP1B3-mediated uptake, respectively. Furthermore, we investigated whether NSAIDs were also substrates for OATP1B1 and OATP1B3 and demonstrated that only diclofenac was significantly transported by OATP1B3, whereas all other NSAIDs investigated were not substrates for these uptake transporters. These results demonstrated that drugs may interact with transport proteins by allosteric mechanisms without being substrates and, therefore, not only uptake inhibition but also allosteric-induced modulation of transport function may be an important mechanism in transporter-mediated drug-drug interactions.

  5. Probenecid, an inhibitor of transmembrane organic anion transporters, alters tissue distribution of DNA adducts in 1-hydroxymethylpyrene-treated rats.

    Science.gov (United States)

    Monien, Bernhard H; Müller, Carolin; Bakhiya, Nadiya; Donath, Claudia; Frank, Heinz; Seidel, Albrecht; Glatt, Hansruedi

    2009-07-28

    1-Methylpyrene (1-MP), an abundant alkylated polycyclic aromatic hydrocarbon, is activated by side-chain hydroxylation to 1-hydroxymethylpyrene (1-HMP) and subsequent sulfo-conjugation to electrophilic 1-sulfooxymethylpyrene (1-SMP). In rats, this activation mainly occurs in liver. 1-SMP may react with hepatic DNA or be exported into the blood circulation to reach other tissues, in particular kidneys. Findings with recombinant cell lines suggest that renal 1-SMP uptake proceeds via organic anion transporters (OATs). Here, we tested the hypothesis that probenecid, a characteristic OAT inhibitor, interferes with kidney damage brought about by 1-SMP formed in rats. 1-HMP was administered intraperitoneally to 30 rats, half of which were co-treated with probenecid. The tissue distribution of DNA adducts was analyzed using (32)P-postlabeling and isotope dilution LC-MS/MS for the detection of the adducts N(2)-(1-methylpyrenyl)-2'-deoxyguanosine and N(6)-(1-methylpyrenyl)-2'-deoxyadenosine. In rats treated solely with 1-HMP, adduct levels in kidney tissue were about 3-fold and 8-fold higher than those in liver and lung, respectively. After co-treatment with probenecid, hepatic and pulmonary adduct levels were 12-fold and 4-fold elevated, respectively, whereas renal adduct levels were slightly lower compared to those of rats receiving 1-HMP alone. Moreover, serum levels of 1-SMP were increased 23-fold in animals pre-treated with probenecid. The differential effects on hepatic and pulmonary adduct levels suggest that not only renal OATs, but also additional anion transporters, e.g. those mediating the hepatic export of 1-SMP into the bile, were inhibited. Thus, transmembrane transport proteins play a crucial role in the distribution of reactive phase II metabolites, and thereby in tissue allocation of DNA adducts.

  6. Interaction of environmental contaminants with zebrafish organic anion transporting polypeptide, Oatp1d1 (Slco1d1)

    Energy Technology Data Exchange (ETDEWEB)

    Popovic, Marta; Zaja, Roko [Laboratory for Molecular Ecotoxicology, Division for Marine and Environmental Research, Rudjer Boskovic Institute, Bijenicka 54, 10 000 Zagreb (Croatia); Fent, Karl [University of Applied Sciences Northwestern Switzerland, School of Life Sciences, Gründenstrasse 40, CH-4132 Muttenz (Switzerland); Swiss Federal Institute of Technology (ETH Zürich), Department of Environmental System Sciences, Institute of Biogeochemistry and Pollution Dynamics, CH-8092 Zürich (Switzerland); Smital, Tvrtko, E-mail: smital@irb.hr [Laboratory for Molecular Ecotoxicology, Division for Marine and Environmental Research, Rudjer Boskovic Institute, Bijenicka 54, 10 000 Zagreb (Croatia)

    2014-10-01

    Polyspecific transporters from the organic anion transporting polypeptide (OATP/Oatp) superfamily mediate the uptake of a wide range of compounds. In zebrafish, Oatp1d1 transports conjugated steroid hormones and cortisol. It is predominantly expressed in the liver, brain and testes. In this study we have characterized the transport of xenobiotics by the zebrafish Oatp1d1 transporter. We developed a novel assay for assessing Oatp1d1 interactors using the fluorescent probe Lucifer yellow and transient transfection in HEK293 cells. Our data showed that numerous environmental contaminants interact with zebrafish Oatp1d1. Oatp1d1 mediated the transport of diclofenac with very high affinity, followed by high affinity towards perfluorooctanesulfonic acid (PFOS), nonylphenol, gemfibrozil and 17α-ethinylestradiol; moderate affinity towards carbaryl, diazinon and caffeine; and low affinity towards metolachlor. Importantly, many environmental chemicals acted as strong inhibitors of Oatp1d1. A strong inhibition of Oatp1d1 transport activity was found by perfluorooctanoic acid (PFOA), chlorpyrifos-methyl, estrone (E1) and 17β-estradiol (E2), followed by moderate to low inhibition by diethyl phthalate, bisphenol A, 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4 tetrahydronapthalene and clofibrate. In this study we identified Oatp1d1 as a first Solute Carrier (SLC) transporter involved in the transport of a wide range of xenobiotics in fish. Considering that Oatps in zebrafish have not been characterized before, our work on zebrafish Oatp1d1 offers important new insights on the understanding of uptake processes of environmental contaminants, and contributes to the better characterization of zebrafish as a model species. - Highlights: • We optimized a novel assay for determination of Oatp1d1 interactors • Oatp1d1 is the first SLC characterized fish xenobiotic transporter • PFOS, nonylphenol, diclofenac, EE2, caffeine are high affinity Oatp1d1substrates • PFOA, chlorpyrifos

  7. Interaction of environmental contaminants with zebrafish organic anion transporting polypeptide, Oatp1d1 (Slco1d1)

    International Nuclear Information System (INIS)

    Popovic, Marta; Zaja, Roko; Fent, Karl; Smital, Tvrtko

    2014-01-01

    Polyspecific transporters from the organic anion transporting polypeptide (OATP/Oatp) superfamily mediate the uptake of a wide range of compounds. In zebrafish, Oatp1d1 transports conjugated steroid hormones and cortisol. It is predominantly expressed in the liver, brain and testes. In this study we have characterized the transport of xenobiotics by the zebrafish Oatp1d1 transporter. We developed a novel assay for assessing Oatp1d1 interactors using the fluorescent probe Lucifer yellow and transient transfection in HEK293 cells. Our data showed that numerous environmental contaminants interact with zebrafish Oatp1d1. Oatp1d1 mediated the transport of diclofenac with very high affinity, followed by high affinity towards perfluorooctanesulfonic acid (PFOS), nonylphenol, gemfibrozil and 17α-ethinylestradiol; moderate affinity towards carbaryl, diazinon and caffeine; and low affinity towards metolachlor. Importantly, many environmental chemicals acted as strong inhibitors of Oatp1d1. A strong inhibition of Oatp1d1 transport activity was found by perfluorooctanoic acid (PFOA), chlorpyrifos-methyl, estrone (E1) and 17β-estradiol (E2), followed by moderate to low inhibition by diethyl phthalate, bisphenol A, 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4 tetrahydronapthalene and clofibrate. In this study we identified Oatp1d1 as a first Solute Carrier (SLC) transporter involved in the transport of a wide range of xenobiotics in fish. Considering that Oatps in zebrafish have not been characterized before, our work on zebrafish Oatp1d1 offers important new insights on the understanding of uptake processes of environmental contaminants, and contributes to the better characterization of zebrafish as a model species. - Highlights: • We optimized a novel assay for determination of Oatp1d1 interactors • Oatp1d1 is the first SLC characterized fish xenobiotic transporter • PFOS, nonylphenol, diclofenac, EE2, caffeine are high affinity Oatp1d1substrates • PFOA, chlorpyrifos

  8. Interactions between crude drug extracts used in Japanese traditional Kampo medicines and organic anion-transporting polypeptide 2B1.

    Science.gov (United States)

    Iijima, Rie; Watanabe, Tomoki; Ishiuchi, Kan'ichiro; Matsumoto, Takashi; Watanabe, Junko; Makino, Toshiaki

    2018-03-25

    The use of herbal medicines has become popular worldwide, and the information on drug interactions between herbal medicines and chemical drugs is needed. We screened the inhibitory effects of crude drugs used in Kampo medicines used in Japan on organic anion-transporting polypeptide (OATP) 2B1 to predict potential interactions between Kampo medicines and chemical drugs used together. We chose 98 kinds of crude drugs frequently used as ingredients of Kampo formulations in Japan and prepared their boiling water extracts. We then screened their inhibitory effects on OATP2B1 by measuring the uptake of estrone 3-sulphate (E3S) by HEK293 cells stably expressing OATP2B1. At the concentration of 100µg/ml, the extracts prepared from 12 kinds of crude drugs, Scuteralliae Radix, Arecae Semen, Aurantii Fructus Immaturus, Perillae Herba, Panacis Japonici Rhizoma, Moutan Cortex, Polygalae Radix, Rhei Rhizoma, Cannabis Fructus, Chrysanthemi Flos, Eriobotryae Folium, and Querci Cortex, suppressed the function of OATP2B1 by less than 20%. The extract of bofutsushosan, a representative Kampo formulation, inhibited OATP2B1 function with sufficient levels to suppress absorption of OATP2B1 substrates in clinics. We further evaluated the inhibitory effects of several ingredients containing Rhei Rhizoma, Perillae Herba, and Moutan Cortex on OATP2B1. Because of crude drugs used in Kampo medicines might suppress absorption of OATP2B1 substrates, these results may contribute to the safe and effective use of Kampo medicine in clinics. A list of abbreviations: EC, (-)-epicatechin; ECG, epicatechin gallate; EGC, epigallocatechin; EGCG, Epigallocatechin gallate; FBS, fetal bovine serum; grapefruit juice; HEK293, Human embryonic kidney; IC 50, The half inhibitory concentration; OATP, organic anion-transporting polypeptide; β-PGG, penta-O-galloyl-β-D-glucose; t.i.d, 3 times a day. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Assessment of Amino Acid/Drug Transporters for Renal Transport of [18F]Fluciclovine (anti-[18F]FACBC in Vitro

    Directory of Open Access Journals (Sweden)

    Masahiro Ono

    2016-10-01

    Full Text Available [18F]Fluciclovine (trans-1-amino-3-[18F]fluorocyclobutanecarboxylic acid; anti-[18F]FACBC, a positron emission tomography tracer used for the diagnosis of recurrent prostate cancer, is transported via amino acid transporters (AATs with high affinity (Km: 97–230 μM. However, the mechanism underlying urinary excretion is unknown. In this study, we investigated the involvement of AATs and drug transporters in renal [18F]fluciclovine reuptake. [14C]Fluciclovine (trans-1-amino-3-fluoro[1-14C]cyclobutanecarboxylic acid was used because of its long half-life. The involvement of AATs in [14C]fluciclovine transport was measured by apical-to-basal transport using an LLC-PK1 monolayer as model for renal proximal tubules. The contribution of drug transporters herein was assessed using vesicles/cells expressing the drug transporters P-glycoprotein (P-gp, breast cancer resistance protein (BCRP, multidrug resistance-associated protein 4 (MRP4, organic anion transporter 1 (OAT1, organic anion transporter 3 (OAT3 , organic cation transporter 2 (OCT2, organic anion transporting polypeptide 1B1 (OATP1B1, and organic anion transporting polypeptide 1B3 (OATP1B3. The apical-to-basal transport of [14C]fluciclovine was attenuated by l-threonine, the substrate for system alanine-serine-cysteine (ASC AATs. [14C]Fluciclovine uptake by drug transporter-expressing vesicles/cells was not significantly different from that of control vesicles/cells. Fluciclovine inhibited P-gp, MRP4, OAT1, OCT2, and OATP1B1 (IC50 > 2.95 mM. Therefore, system ASC AATs may be partly involved in the renal reuptake of [18F]fluciclovine. Further, given that [18F]fluciclovine is recognized as an inhibitor with millimolar affinity for the tested drug transporters, slow urinary excretion of [18F]fluciclovine may be mediated by system ASC AATs, but not by drug transporters.

  10. Impaired activity of bile bile canalicular organic anion transporter (Mrp2/cmoat) is not the main cause of ethinylestradiol-induced cholestasis in the rat

    NARCIS (Netherlands)

    Koopen, NR; Wolters, H; Havinga, R; Vonk, RJ; Jansen, PLM; Muller, M; Kuipers, F

    To test the hypothesis that impaired activity of the bile canalicular organic anion transporting system mrp2 (cmoat) is a key event in the etiology of 17 alpha-ethinylestradiol (EE)-induced intrahepatic cholestasis in rats, EE (5 mg/kg subcutaneously daily) was administered to male normal Wistar

  11. Carbon dioxide transport in alligator blood and its erythrocyte permeability to anions and water

    DEFF Research Database (Denmark)

    Jensen, F B; Wang, T; Jones, D R

    1998-01-01

    + binding. Erythrocyte volume, plasma pH, and plasma HCO3- concentration also varied little with the degree of oxygenation. Diffusional water permeability was higher in oxygenated than deoxygenated RBCs. The RBCs have rapid band 3-mediated Cl- and HCO3- transport, which was not affected by degree...

  12. Interactions between organic anions on multiple transporters in Caco-2 cells

    DEFF Research Database (Denmark)

    Grandvuinet, Anne Sophie; Steffansen, Bente

    2011-01-01

    Caco-2 cell line may be used as an overall model to predict interactions on multiple membrane transporters in the intestine. Taurocholic acid (TCA) and estrone-3-sulfate (E1S) were used as model substrates. Possible inhibitors studied were TCA, E1S, taurolithocholic acid, fluvastatin, and glipizide...

  13. The role of organic anion transporting polypeptides in drug absorption, distribution, excretion and drug-drug interactions.

    Science.gov (United States)

    Kovacsics, Daniella; Patik, Izabel; Özvegy-Laczka, Csilla

    2017-04-01

    The in vivo fate and effectiveness of a drug depends highly on its absorption, distribution, metabolism, excretion and toxicity (ADME-Tox). Organic anion transporting polypeptides (OATPs) are membrane proteins involved in the cellular uptake of various organic compounds, including clinically used drugs. Since OATPs are significant players in drug absorption and distribution, modulation of OATP function via pharmacotherapy with OATP substrates/inhibitors, or modulation of their expression, affects drug pharmacokinetics. Given their cancer-specific expression, OATPs may also be considered anticancer drug targets. Areas covered: We describe the human OATP family, discussing clinically relevant consequences of altered OATP function. We offer a critical analysis of published data on the role of OATPs in ADME and in drug-drug interactions, especially focusing on OATP1A2, 1B1, 1B3 and 2B1. Expert opinion: Four members of the OATP family, 1A2, 1B1, 1B3 and 2B1, have been characterized in detail. As biochemical and pharmacological knowledge on the other OATPs is lacking, it seems timely to direct research efforts towards developing the experimental framework needed to investigate the transport mechanism and substrate specificity of the poorly described OATPs. In addition, elucidating the role of OATPs in tumor development and therapy response are critical avenues for further research.

  14. Role of glutathione transport processes in kidney function

    International Nuclear Information System (INIS)

    Lash, Lawrence H.

    2005-01-01

    The kidneys are highly dependent on an adequate supply of glutathione (GSH) to maintain normal function. This is due, in part, to high rates of aerobic metabolism, particularly in the proximal tubules. Additionally, the kidneys are potentially exposed to high concentrations of oxidants and reactive electrophiles. Renal cellular concentrations of GSH are maintained by both intracellular synthesis and transport from outside the cell. Although function of specific carriers has not been definitively demonstrated, it is likely that multiple carriers are responsible for plasma membrane transport of GSH. Data suggest that the organic anion transporters OAT1 and OAT3 and the sodium-dicarboxylate 2 exchanger (SDCT2 or NaDC3) mediate uptake across the basolateral plasma membrane (BLM) and that the organic anion transporting polypeptide OATP1 and at least one of the multidrug resistance proteins mediate efflux across the brush-border plasma membrane (BBM). BLM transport may be used pharmacologically to provide renal proximal tubular cells with exogenous GSH to protect against oxidative stress whereas BBM transport functions physiologically in turnover of cellular GSH. The mitochondrial GSH pool is derived from cytoplasmic GSH by transport into the mitochondrial matrix and is mediated by the dicarboxylate and 2-oxoglutarate exchangers. Maintenance of the mitochondrial GSH pool is critical for cellular and mitochondrial redox homeostasis and is important in determining susceptibility to chemically induced apoptosis. Hence, membrane transport processes are critical to regulation of renal cellular and subcellular GSH pools and are determinants of susceptibility to cytotoxicity induced by oxidants and electrophiles

  15. Lansoprazole Exacerbates Pemetrexed-Mediated Hematologic Toxicity by Competitive Inhibition of Renal Basolateral Human Organic Anion Transporter 3.

    Science.gov (United States)

    Ikemura, Kenji; Hamada, Yugo; Kaya, Chinatsu; Enokiya, Tomoyuki; Muraki, Yuichi; Nakahara, Hiroki; Fujimoto, Hajime; Kobayashi, Tetsu; Iwamoto, Takuya; Okuda, Masahiro

    2016-10-01

    Pemetrexed, a multitargeted antifolate, is eliminated by tubular secretion via human organic anion transporter 3 (hOAT3). Although proton pump inhibitors (PPIs) are frequently used in cancer patients, the drug interaction between PPIs and pemetrexed remains to be clarified. In this study, we examined the drug interaction between pemetrexed and PPIs in hOAT3-expressing cultured cells, and retrospectively analyzed the impact of PPIs on the development of hematologic toxicity in 108 patients who received pemetrexed and carboplatin treatment of nonsquamous non-small cell lung cancer for the first time between January 2011 and June 2015. We established that pemetrexed was transported via hOAT3 (Km = 68.3 ± 11.1 µM). Lansoprazole, rabeprazole, pantoprazole, esomeprazole, omeprazole, and vonoprazan inhibited hOAT3-mediated uptake of pemetrexed in a concentration-dependent manner. The inhibitory effect of lansoprazole was much greater than those of other PPIs and the apparent IC50 value of lansoprazole against pemetrexed transport via hOAT3 was 0.57 ± 0.17 µM. The inhibitory type of lansoprazole was competitive. In a retrospective study, multivariate analysis revealed that coadministration of lansoprazole, but not other PPIs, with pemetrexed and carboplatin was an independent risk factor significantly contributing to the development of hematologic toxicity (odds ratio: 10.004, P = 0.005). These findings demonstrated that coadministration of lansoprazole could exacerbate the hematologic toxicity associated with pemetrexed, at least in part, by competitive inhibition of hOAT3. Our results would aid clinicians to make decisions of coadministration drugs to avoid drug interaction-induced side effects for achievement of safe and appropriate chemotherapy with pemetrexed. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

  16. Expression of organic anion transporting polypeptide 1c1 and monocarboxylate transporter 8 in the rat placental barrier and the compensatory response to thyroid dysfunction.

    Directory of Open Access Journals (Sweden)

    Yi-na Sun

    Full Text Available Thyroid hormones (THs must pass from mother to fetus for normal fetal development and require the expression of placental TH transporters. We investigate the compensatory effect of placental organic anion transporting polypeptide 1c1 (Oatp1c1 and monocarboxylate transporter 8 (Mct8 on maternal thyroid dysfunction. We describe the expressions of these two transporters in placental barriers and trophoblastic cell populations in euthyroidism and thyroid dysfunction resulting from differential iodine nutrition at gestation day (GD 16 and 20, that is, before and after the onset of fetal thyroid function. Immunohistochemistry revealed that in the blood-placenta barrier, these two TH transporters were strongly expressed in the villous interstitial substance and were weakly expressed in trophoblast cells. Levels of Oatp1c1 protein obviously increased in the placental fetal portion during maternal thyroid deficiency at GD16. Under maternal thyroid deficiency after the production of endogenous fetal TH, quantitative PCR analysis revealed down-regulation of Oatp1c1 occurred along with up-regulation of Mct8 in trophoblast cell populations isolated by laser capture microdissection (LCM; this was consistent with the protein levels in the fetal portion of the placenta. In addition, decreased D3 mRNA at GD16 and increased D2 mRNA on two gestational days were observed in trophoblast cells with thyroid dysfunction. However, levels of Oatp1c1 mRNA at GD16 and D3 mRNA at GD20 were too low to be detectable in trophoblast cells. In conclusion, placental Oatp1c1 plays an essential compensatory role when the transplacental passage of maternal THs is insufficient at the stage before the fetal TH production. In addition, the coordinated effects of Oatp1c1, Mct8, D2 and D3 in the placental barrier may regulate both transplacental TH passage and the development of trophoblast cells during thyroid dysfunction throughout the pregnancy.

  17. The liver and kidney expression of sulfate anion transporter sat-1 in rats exhibits male-dominant gender differences.

    Science.gov (United States)

    Brzica, Hrvoje; Breljak, Davorka; Krick, Wolfgang; Lovrić, Mila; Burckhardt, Gerhard; Burckhardt, Birgitta C; Sabolić, Ivan

    2009-04-01

    The sulfate anion transporter (sat-1, Slc26a1) has been cloned from rat liver, functionally characterized, and localized to the sinusoidal membrane in hepatocytes and basolateral membrane (BLM) in proximal tubules (PT). Here, we confirm previously described localization of sat-1 protein in rat liver and kidneys and report on gender differences (GD) in its expression by immunochemical, transport, and excretion studies in rats. The approximately 85-kDa sat-1 protein was localized to the sinusoidal membrane in hepatocytes and BLM in renal cortical PT, with the male-dominant expression. However, the real-time reverse-transcription polymerase chain reaction data indicated no GD at the level of sat-1 mRNA. In agreement with the protein data, isolated membranes from both organs exhibited the male-dominant exchange of radiolabeled sulfate for oxalate, whereas higher oxalate in plasma and 24-h urine indicated higher oxalate production and excretion in male rats. Furthermore, the expression of liver, but not renal, sat-1 protein was: unaffected by castration, upregulated by ovariectomy, and downregulated by estrogen or progesterone treatment in males. Therefore, GD (males > females) in the expression of sat-1 protein in rat liver (and, possibly, kidneys) are caused by the female sex-hormone-driven inhibition at the posttranscriptional level. The male-dominant abundance of sat-1 protein in liver may conform to elevated uptake of sulfate and extrusion of oxalate, causing higher plasma oxalate in males. Oxalate is then excreted by the kidneys via the basolateral sat-1 (males > females) and the apical CFEX (Slc26a6; GD unknown) in PT and eliminated in the urine (males > females), where it may contribute to the male-prevailing development of oxalate urolithiasis.

  18. Novel insights into xenobiotic transport by organic anion transporting polypeptides (OATPs) and OATP-expression profiling in ovarian carcinoma and other solid tumors

    International Nuclear Information System (INIS)

    Svoboda, M.

    2010-01-01

    Eleven members of the organic anion transporting polypeptides (OATP) family have been identified in humans. They are responsible for the Na+ independent cellular uptake of a broad range of substances. The aim of this thesis was to investigate the possible role of OATPs present in various cancer entities including breast, bone, liver and ovary. In the first study, carrier-mediated uptake of paclitaxel was studied in X. laevis oocytes expressing all known human OATPs and in ovarian cancer cell lines. OATP1B1 could be identified as an uptake transporter for paclitaxel showing a Km value of 0.6 μM indicating high affinity to this taxane. Subsequently, the expression status of OATPs and several ABC transporters was assessed in malignant specimens from 191 ovarian cancer patients. OATP3A1 was significantly correlated with the FIGO stage of tumors. Moreover, OATP6A1, ABCB2 and ABCC3 were identified as highly significant predictor for the disease free survival of ovarian cancer patients. In additional studies we showed distinct OATP expression patterns in cancer tissues compared to normal tissue or benign tumors. In general, higher OATP levels were detected in normal tissues compared to malignant ones in breast cancer as well as bone cancer. In liver cancer, we observed upregulation of OATP2A1 and 5A1 in primary and secondary hepatic tumors but OATP4A1 was only upregulated in secondary hepatic tumors. The distinct expression pattern for individual OATPs in tumor cells suggest their specific functions which may involve transport of molecules important for cellular signaling as well as of drugs used in therapy. (author) [de

  19. Contribution of the organic anion transporter OAT2 to the renal active tubular secretion of creatinine and mechanism for serum creatinine elevations caused by cobicistat

    Science.gov (United States)

    Lepist, Eve-Irene; Zhang, Xuexiang; Hao, Jia; Huang, Jane; Kosaka, Alan; Birkus, Gabriel; Murray, Bernard P; Bannister, Roy; Cihlar, Tomas; Huang, Yong; Ray, Adrian S

    2014-01-01

    Many xenobiotics including the pharmacoenhancer cobicistat increase serum creatinine by inhibiting its renal active tubular secretion without affecting the glomerular filtration rate. This study aimed to define the transporters involved in creatinine secretion, applying that knowledge to establish the mechanism for xenobiotic-induced effects. The basolateral uptake transporters organic anion transporter OAT2 and organic cation transporters OCT2 and OCT3 were found to transport creatinine. At physiologic creatinine concentrations, the specific activity of OAT2 transport was over twofold higher than OCT2 or OCT3, establishing OAT2 as a likely relevant creatinine transporter and further challenging the traditional view that creatinine is solely transported by a cationic pathway. The apical multidrug and toxin extrusion transporters MATE1 and MATE2-K demonstrated low-affinity and high-capacity transport. All drugs known to affect creatinine inhibited OCT2 and MATE1. Similar to cimetidine and ritonavir, cobicistat had the greatest effect on MATE1 with a 50% inhibition constant of 0.99 μM for creatinine transport. Trimethoprim potently inhibited MATE2-K, whereas dolutegravir preferentially inhibited OCT2. Cimetidine was unique, inhibiting all transporters that interact with creatinine. Thus, the clinical observation of elevated serum creatinine in patients taking cobicistat is likely a result of OCT2 transport, facilitating intracellular accumulation, and MATE1 inhibition. PMID:24646860

  20. Age- and sex-related differences of organic anion-transporting polypeptide gene expression in livers of rats

    International Nuclear Information System (INIS)

    Hou, Wei-Yu; Xu, Shang-Fu; Zhu, Qiong-Ni; Lu, Yuan-Fu; Cheng, Xing-Guo; Liu, Jie

    2014-01-01

    Organic anion-transporting polypeptides (Oatps) play important roles in transporting endogenous substances and xenobiotics into the liver and are implicated in drug-drug interactions. Many factors could influence their expression and result in alterations in drug disposition, efficacy and toxicity. This study was aimed to examine the development-, aging-, and sex-dependent Oatps expression in livers of rats. The livers from SD rats during development (− 2, 1, 7, 14, 21, 28, 35, and 60 d) and aging (60, 180, 540 and/or 800 d) were collected and total RNAs were extracted, purified, and subjected to real-time PCR analysis. Total proteins were extracted for western-blot analysis. Results showed that Oatp1a1, Oatp1a4, Oatp1a5 and Oatp1b2 were all hardly detectable in fetal rat livers, low at birth, rapidly increased after weaning (21 d), and reached the peak at 60 d. The Oatps remained stable during the age between 60–180 d, and decreased at elderly (540 and/or 800 d). After birth, Oatp1a1, Oatp1a4, and Oatp1b2 were all highly expressed in liver, in contrast, Oatp1a5 expression was low. Oatp expressions are male-predominant in rat livers. In the livers of aged rats, the Oatp expression decreased and shared a consistent ontogeny pattern at the mRNA and protein level. In conclusion, this study showed that in rat liver, Oatp1a1, Oatp1a4, Oatp1a5 and Oatp1b2 gene expressions are influenced by age and gender, which could provide a basis of individual variation in drug transport, metabolism and toxicity in children, elderly and women. - Highlights: • Oatp1a1, Oatp1a4, Oatp1a5 and Oatp1b2 expression in livers of rats. • Ontogenic changes of Oatps at − 2, 1, 7, 14, 21, 28, 35, and 60 days. • Age-related changes of Oatps at 60, 180, 540, and 800 days. • Sex-difference of Oatps at the both mRNA and protein levels

  1. Age- and sex-related differences of organic anion-transporting polypeptide gene expression in livers of rats

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Wei-Yu; Xu, Shang-Fu; Zhu, Qiong-Ni; Lu, Yuan-Fu [Key Lab for Pharmacology of Ministry of Education, Zunyi Medical College, Zunyi 563003 (China); Cheng, Xing-Guo [Department of Pharmaceutical Sciences, St. John’s University, New York, NY 11439 (United States); Liu, Jie, E-mail: Jieliu@zmc.edu.cn [Key Lab for Pharmacology of Ministry of Education, Zunyi Medical College, Zunyi 563003 (China)

    2014-10-15

    Organic anion-transporting polypeptides (Oatps) play important roles in transporting endogenous substances and xenobiotics into the liver and are implicated in drug-drug interactions. Many factors could influence their expression and result in alterations in drug disposition, efficacy and toxicity. This study was aimed to examine the development-, aging-, and sex-dependent Oatps expression in livers of rats. The livers from SD rats during development (− 2, 1, 7, 14, 21, 28, 35, and 60 d) and aging (60, 180, 540 and/or 800 d) were collected and total RNAs were extracted, purified, and subjected to real-time PCR analysis. Total proteins were extracted for western-blot analysis. Results showed that Oatp1a1, Oatp1a4, Oatp1a5 and Oatp1b2 were all hardly detectable in fetal rat livers, low at birth, rapidly increased after weaning (21 d), and reached the peak at 60 d. The Oatps remained stable during the age between 60–180 d, and decreased at elderly (540 and/or 800 d). After birth, Oatp1a1, Oatp1a4, and Oatp1b2 were all highly expressed in liver, in contrast, Oatp1a5 expression was low. Oatp expressions are male-predominant in rat livers. In the livers of aged rats, the Oatp expression decreased and shared a consistent ontogeny pattern at the mRNA and protein level. In conclusion, this study showed that in rat liver, Oatp1a1, Oatp1a4, Oatp1a5 and Oatp1b2 gene expressions are influenced by age and gender, which could provide a basis of individual variation in drug transport, metabolism and toxicity in children, elderly and women. - Highlights: • Oatp1a1, Oatp1a4, Oatp1a5 and Oatp1b2 expression in livers of rats. • Ontogenic changes of Oatps at − 2, 1, 7, 14, 21, 28, 35, and 60 days. • Age-related changes of Oatps at 60, 180, 540, and 800 days. • Sex-difference of Oatps at the both mRNA and protein levels.

  2. Up-regulation of the multidrug resistance genes, Mrp1 and Mdr1b, and down-regulation of the organic anion transporter, Mrp2, and the bile salt transporter, Spgp, in endotoxemic rat liver

    NARCIS (Netherlands)

    Vos, T. A.; Hooiveld, G. J.; Koning, H.; Childs, S.; Meijer, D. K.; Moshage, H.; Jansen, P. L.; Müller, M.

    1998-01-01

    Endotoxin-induced cholestasis is mainly caused by an impaired canalicular secretion. Mrp2, the canalicular multispecific organic anion transporter, is strongly down-regulated in this situation, and canalicular bile salt secretion is also reduced. We hypothesized that other adenosine

  3. Up-regulation of the multidrug resistance genes, mrp1 and mdr1b, and down regulation of the organic anion transporter, mrp2, and the bile salt transporter, spgp, in endotoxemic rat liver

    NARCIS (Netherlands)

    Vos, T; Hooiveld, GJE; Konong, H; Childs, S; Meijer, DKF; Moshage, H; Jansen, PLM; Muller, M

    Endotoxin-induced cholestasis is mainly caused by an impaired canalicular secretion. Mrp2, the canalicular multispecific organic anion transporter, is strongly down-regulated in this situation, and canalicular bile salt secretion is also reduced. We hypothesized that other adenosine

  4. Involvement of organic anion transporting polypeptide 1a5 (Oatp1a5) in intestinal absorption of endothelin receptor antagonist in rats

    DEFF Research Database (Denmark)

    Tani, Takeshe; Gram, Luise Kvisgaard; Arakawa, Hiroshi

    2008-01-01

    PURPOSE: To assess the contribution of organic anion transporting polypeptide 1a5 (Oatp1a5/Oatp3) in the intestinal absorption of an orally active endothelin receptor antagonist, (+)-(5S,6R,7R)-2-butyl-7-[2-((2S)-2-carboxypropyl)-4-methoxyphenyl]-5-(3,4-methylene-dioxyphenyl)cyclopenteno[1,2-b...... and taurocholic acid. CONCLUSIONS: These results consistently suggested that Oatp1a5 is contributing to the intestinal absorption of compound-A at least in part, and the transporter-mediated absorption seems to be maximized at the acidic microenvironment of epithelial cells in the small intestine in rats....

  5. Comparative pharmacophore modeling of organic anion transporting polypeptides: a meta-analysis of rat Oatp1a1 and human OATP1B1.

    Science.gov (United States)

    Chang, Cheng; Pang, K Sandy; Swaan, Peter W; Ekins, Sean

    2005-08-01

    The organic anion transporting polypeptides OATPs are key membrane transporters for which crystal structures are not currently available. They transport a diverse array of xenobiotics and are expressed at the interface of hepatocytes, renal tubular cells, enterocytes, and the choroid plexus. To aid the understanding of the key molecular features for substrate-transporter interactions, pharmacophore models were produced for the two OATPs that have been most extensively studied, namely rat Oatp1a1 and human OATP1B1. Literature data from Chinese hamster ovary, HeLa, human embryonic kidney 293 cells, and Xenopus laevis oocytes were used to construct pharmacophores for each individual transporter which were later merged to show similarities across cell lines for the same transporter. Additionally, meta-pharmacophores were generated from the combined datasets of each cell system used with the same transporter. The pharmacophores for each transporter consisted of hydrogen bond acceptor and hydrophobic features. There was good agreement between the merged and meta-pharmacophores containing two hydrogen bond acceptors and two or three hydrophobic features for Oatp1a1 and OATP1B1. External test sets were used to validate the individual pharmacophores. The meta-pharmacophores were also used to make predictions for molecules not included in the models and provided new molecular insight into the key features for these OATP transporters. This approach can be extended to other transporters for which limited data are available.

  6. JBP485 improves gentamicin-induced acute renal failure by regulating the expression and function of Oat1 and Oat3 in rats

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xinjin [Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, Dalian (China); Meng, Qiang; Liu, Qi; Wang, Changyuan; Sun, Huijun; Peng, Jinyong; Ma, Xiaochi [Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, Dalian (China); Provincial Key Laboratory for Pharmacokinetics and Transport, Dalian Medical University, Liaoning (China); Kaku, Taiichi [Japan Bioproducts Industry Co. Ltd., Tomigaya, Shibuya-ku, Tokyo (Japan); Liu, Kexin, E-mail: kexinliu@dlmedu.edu.cn [Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, Dalian (China); Provincial Key Laboratory for Pharmacokinetics and Transport, Dalian Medical University, Liaoning (China)

    2013-09-01

    We investigated the effects of JBP485 (an anti-inflammatory dipeptide and a substrate of OAT) on regulation of the expression and function of renal Oat1 and Oat3, which can accelerate the excretion of accumulated uremic toxins (e.g. indoxyl sulfate) in the kidney to improve gentamicin-induced ARF in rats. JBP485 caused a significant decrease in the accumulation of endogenous substances (creatinine, blood urea nitrogen and indoxyl sulfate) in vivo, an increase in the excretion of exogenous compounds (lisinopril and inulin) into urine, and up-regulation of the expressions of renal Oat1 and Oat3 in the kidney tissues and slices via substrate induction. To determine the effect of JBP485 on the accelerated excretion of uremic toxins mediated by Oat1 and Oat3, the mRNA and protein expression levels of renal basolateral Oats were assessed by quantitative real-time PCR, western blot, immunohistochemical analysis and an immunofluorescence method. Gentamicin down-regulated the expression of Oats mRNA and protein in rat kidney, and these effects were reversed after administration of JBP485. In addition, JBP485 caused a significant decrease in MPO and MDA levels in the kidney, and improved the pathological condition of rat kidney. These results indicated that JBP485 improved acute renal failure by increasing the expression and function of Oat1 and Oat3, and by decreasing overoxidation of the kidney in gentamicin-induced ARF rats. - Highlights: • JBP485 could up-regulate function and expression of Oat1 and Oat3 in kidney. • Effects of JBP485 on ARF are mediated by stimulating excretion of uremic toxins. • JBP485 protected against gentamicin-induced ARF by decreasing MPO and MDA.

  7. Relation between heat of vaporization, ion transport, molar volume, and cation-anion binding energy for ionic liquids.

    Science.gov (United States)

    Borodin, Oleg

    2009-09-10

    A number of correlations between heat of vaporization (H(vap)), cation-anion binding energy (E(+/-)), molar volume (V(m)), self-diffusion coefficient (D), and ionic conductivity for 29 ionic liquids have been investigated using molecular dynamics (MD) simulations that employed accurate and validated many-body polarizable force fields. A significant correlation between D and H(vap) has been found, while the best correlation was found for -log(DV(m)) vs H(vap) + 0.28E(+/-). A combination of enthalpy of vaporization and a fraction of the cation-anion binding energy was suggested as a measure of the effective cohesive energy for ionic liquids. A deviation of some ILs from the reported master curve is explained based upon ion packing and proposed diffusion pathways. No general correlations were found between the ion diffusion coefficient and molecular volume or the diffusion coefficient and cation/anion binding energy.

  8. Changes in expression of renal Oat1, Oat3 and Mrp2 in cisplatin-induced acute renal failure after treatment of JBP485 in rats

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Tao, E-mail: liutaomedical@qq.com [Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, 9 West Section, Lvshun South Road, Lvshunkou District, Dalian 116044 (China); Meng, Qiang, E-mail: mengq531@yahoo.cn [Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, 9 West Section, Lvshun South Road, Lvshunkou District, Dalian 116044 (China); Provincial Key Laboratory for Pharmacokinetics and Transport, Liaoning, Dalian Medical University (China); Wang, Changyuan, E-mail: wangcyuan@163.com [Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, 9 West Section, Lvshun South Road, Lvshunkou District, Dalian 116044 (China); Provincial Key Laboratory for Pharmacokinetics and Transport, Liaoning, Dalian Medical University (China); Liu, Qi, E-mail: llaqii@yahoo.com.cn [Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, 9 West Section, Lvshun South Road, Lvshunkou District, Dalian 116044 (China); Provincial Key Laboratory for Pharmacokinetics and Transport, Liaoning, Dalian Medical University (China); Guo, Xinjin, E-mail: guo.xinjin@163.com [Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, 9 West Section, Lvshun South Road, Lvshunkou District, Dalian 116044 (China); Sun, Huijun, E-mail: sunhuijun@hotmail.com [Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, 9 West Section, Lvshun South Road, Lvshunkou District, Dalian 116044 (China); Provincial Key Laboratory for Pharmacokinetics and Transport, Liaoning, Dalian Medical University (China); Peng, Jinyong, E-mail: jinyongpeng2005@163.com [Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, 9 West Section, Lvshun South Road, Lvshunkou District, Dalian 116044 (China); Provincial Key Laboratory for Pharmacokinetics and Transport, Liaoning, Dalian Medical University (China); and others

    2012-11-01

    The purpose of this study is to investigate whether the effect of cyclo-trans-4-L-hydroxyprolyl-L-serine (JBP485) on acute renal failure (ARF) induced by cisplatin is related to change in expression of renal Oat1, Oat3 and Mrp2 in rats. JBP485 reduced creatinine, blood urea nitrogen (BUN) and indoxyl sulfate (IS) in plasma and malondialdehyde (MDA) in kidney, and recovered the glomerular filtration rate (GFR) and the activity of superoxide dismutase (SOD) in cisplatin-treated rats. The plasma concentration of PAH (para-aminohippurate) determined by LC–MS/MS was increased markedly after intravenous administration of cisplatin, whereas cumulative urinary excretion of PAH and the uptake of PAH in kidney slices were significantly decreased. qRT-PCR and Western-blot showed a decrease in mRNA and protein of Oat1 and Oat3, an increase in mRNA and protein of Mrp2 in cisplatin-treated rats, and an increase in IS (a uremic toxin) after co-treatment with JBP485. It indicated that JBP485 promoted urinary excretion of toxins by upregulating renal Mrp2. This therefore gives in part the explanation about the mechanism by which JBP485 improves ARF induced by cisplatin in rats. -- Highlights: ► Cisplatin induces acute renal failure (ARF). ► The expression of Oat1, Oat3 and Mrp2 were changed during ARF. ► The regulated expression of Oat1, Oat3 and Mrp2 is an adaptive protected response. ► JBP485 could facilitate the adaptive protective action.

  9. Changes in expression of renal Oat1, Oat3 and Mrp2 in cisplatin-induced acute renal failure after treatment of JBP485 in rats

    International Nuclear Information System (INIS)

    Liu, Tao; Meng, Qiang; Wang, Changyuan; Liu, Qi; Guo, Xinjin; Sun, Huijun; Peng, Jinyong

    2012-01-01

    The purpose of this study is to investigate whether the effect of cyclo-trans-4-L-hydroxyprolyl-L-serine (JBP485) on acute renal failure (ARF) induced by cisplatin is related to change in expression of renal Oat1, Oat3 and Mrp2 in rats. JBP485 reduced creatinine, blood urea nitrogen (BUN) and indoxyl sulfate (IS) in plasma and malondialdehyde (MDA) in kidney, and recovered the glomerular filtration rate (GFR) and the activity of superoxide dismutase (SOD) in cisplatin-treated rats. The plasma concentration of PAH (para-aminohippurate) determined by LC–MS/MS was increased markedly after intravenous administration of cisplatin, whereas cumulative urinary excretion of PAH and the uptake of PAH in kidney slices were significantly decreased. qRT-PCR and Western-blot showed a decrease in mRNA and protein of Oat1 and Oat3, an increase in mRNA and protein of Mrp2 in cisplatin-treated rats, and an increase in IS (a uremic toxin) after co-treatment with JBP485. It indicated that JBP485 promoted urinary excretion of toxins by upregulating renal Mrp2. This therefore gives in part the explanation about the mechanism by which JBP485 improves ARF induced by cisplatin in rats. -- Highlights: ► Cisplatin induces acute renal failure (ARF). ► The expression of Oat1, Oat3 and Mrp2 were changed during ARF. ► The regulated expression of Oat1, Oat3 and Mrp2 is an adaptive protected response. ► JBP485 could facilitate the adaptive protective action.

  10. Prediction of the overall renal tubular secretion and hepatic clearance of anionic drugs and a renal drug-drug interaction involving organic anion transporter 3 in humans by in vitro uptake experiments.

    Science.gov (United States)

    Watanabe, Takao; Kusuhara, Hiroyuki; Watanabe, Tomoko; Debori, Yasuyuki; Maeda, Kazuya; Kondo, Tsunenori; Nakayama, Hideki; Horita, Shigeru; Ogilvie, Brian W; Parkinson, Andrew; Hu, Zhuohan; Sugiyama, Yuichi

    2011-06-01

    The present study investigated prediction of the overall renal tubular secretion and hepatic clearances of anionic drugs based on in vitro transport studies. The saturable uptake of eight drugs, most of which were OAT3 substrates (rosuvastatin, pravastatin, pitavastatin, valsartan, olmesartan, trichlormethiazide, p-aminohippurate, and benzylpenicillin) by freshly prepared human kidney slices underestimated the overall intrinsic clearance of the tubular secretion; therefore, a scaling factor of 10 was required for in vitro-in vivo extrapolation. We examined the effect of gemfibrozil and its metabolites, gemfibrozil glucuronide and the carboxylic metabolite, gemfibrozil M3, on pravastatin uptake by human kidney slices. The inhibition study using human kidney slices suggests that OAT3 plays a predominant role in the renal uptake of pravastatin. Comparison of unbound concentrations and K(i) values (1.5, 9.1, and 4.0 μM, for gemfibrozil, gemfibrozil glucuronide, and gemfibrozil M3, respectively) suggests that the mechanism of the interaction is due mainly to inhibition by gemfibrozil and gemfibrozil glucuronide. Furthermore, extrapolation of saturable uptake by cryopreserved human hepatocytes predicts clearance comparable with the observed hepatic clearance although fluvastatin and rosuvastatin required a scaling factor of 11 and 6.9, respectively. This study suggests that in vitro uptake assays using human kidney slices and hepatocytes provide a good prediction of the overall tubular secretion and hepatic clearances of anionic drugs and renal drug-drug interactions. It is also recommended that in vitro-in vivo extrapolation be performed in animals to obtain more reliable prediction.

  11. Green tea polyphenols decreases uric acid level through xanthine oxidase and renal urate transporters in hyperuricemic mice.

    Science.gov (United States)

    Chen, Gang; Tan, Ming-Liang; Li, Kai-Kai; Leung, Ping-Chung; Ko, Chun-Hay

    2015-12-04

    Green tea is a Chinese materia medica with the main functions of "inducing urination and quenching thirst". Green tea polyphenols (GTP) are generally acknowledged as the main active fraction with multiple pharmacological functions in green tea. However, the effect of GTP on hyperuricemia is not clear till now. The present study was carried out to investigate the effect of GTP on serum level of uric acid in potassium oxonate (PO)-induced hyperuricemic mice, and explore the underlying mechanisms from two aspects of production and excretion of uric acid. PO and GTP were intragastricly administered to mice for consecutive 7 days. Serum level of uric acid, and xanthine oxidase (XOD) activity in serum and liver were examined. Simultaneously, expression of XOD protein in liver was analyzed by Western blot assay. Expressions of urate transporters including urate-anion transporter (URAT) 1, organic anion transporter (OAT) 1 and 3 in kidney were analyzed by immunohistochemistry staining method. 300 and 600 mg/kg GTP significantly decreased serum level of uric acid of hyperuricemic mice in a dose-dependent manner (p<0.05 or p<0.01). Besides, 300 and 600 mg/kg GTP markedly reduced XOD activity in serum and liver of hyperuricemic mice (both p<0.01). Furthermore, 300 and 600 mg/kg GTP clearly reduced XOD expression in liver, as well as reduced URAT1 expression and increased OAT1 and OAT3 expressions in kidney of hyperuricemic mice (p<0.05 or p<0.01). These results demonstrated that GTP had the effect of lowering uric acid through decreasing the uric acid production and increasing uric acid excretion. Our study suggested that GTP would be a promising candidate as a novel hypouricaemic agent for further investigation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. The eighth and ninth transmembrane domains in organic anion transporting polypeptide 1B1 affect the transport kinetics of estrone-3-sulfate and estradiol-17beta-D-glucuronide.

    Science.gov (United States)

    Miyagawa, Mayuko; Maeda, Kazuya; Aoyama, Akinori; Sugiyama, Yuichi

    2009-05-01

    Organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 are responsible for the hepatic uptake of organic anions. They share similar sequences and structures with 12 putative transmembrane domains (TMs). Their substrate specificities are very broad and overlap each other, whereas each transporter specifically recognizes certain substrates. Because the homology of the amino acid sequence in the latter part of OATP1B1 and OATP1B3 is relatively low, to determine which TMs in the latter part of OATP1B1 are important for its substrate recognition, we constructed several cell lines expressing chimeric transporters in which some TMs of OATP1B1 were substituted with those of OATP1B3, and we investigated the transport kinetics of estrone-3-sulfate (E-sul; a substrate preferentially accepted by OATP1B1) and estradiol-17beta-D-glucuronide (EG; a substrate accepted by both transporters). As the number of substituted TMs at the N terminus with those of OATP1B3 increased, the K(m) value of E-sul greatly increased and its uptake clearance decreased. The substitution of TM7 or TM9 of OATP1B1 with that of OATP1B3 (named 1B1-TM7 or 1B1-TM9) did not change the transport kinetics of EG, whereas the K(m) value of E-sul in 1B1-TM9 increased 7.4-fold. Conversely, the substitution of TM8 resulted in an 18-fold increase in the K(m) value of E-sul and abolished the transporter-mediated uptake of EG. These results suggest that TM8 in OATP1B1 is critical for the substrate recognition of both E-sul and EG and that TM9 is important for the recognition of E-sul, whereas it is interchangeable with that of OATP1B3 for EG transport.

  13. [Dynamics of ultrastructure changes in sheet plate fiber flax with braking transport assimilate by nitrate-anion].

    Science.gov (United States)

    Abdrakhimov, F A; Batasheva, S N; Bakirova, G G; Chikov, V I

    2008-01-01

    Changes in leaf mesophyll cell ultrastructure under nitrate feeding into the apoplast of common flax (Linum usitatissimum L.) in the form of 50 mM KNO3 solution were studied. In 30 min after the beginning of nitrate feeding through the transpiration water stream, swelling of mitochondrial and microbodies, clarification of their matrices, and curling of dictyosome discs into annular structures were observed. These events characterized symplastic domain formed by mesophyll, bundle sheath and phloem parenchyma cells, and were not found in companion cell-sieve element complex. Simultaneously, formation of large central vacuoles in companion cells was noted. Restoration of organelle structures in assimilating cells and phloem parenchyma in 1-2 h after treatment was accompanied by enhancement of morphological changes in phloem elements and companion cells and signs of plasmolysis in the mesophyll cells. It was supposed that the two-phase character of changes in leaf organelle ultrastructure and photosynthesis might reflect duality of leaf cell response to nitrate ion. The rapid alterations of the structure can be coupled with direct influence of the anion on cell metabolism and(or) with signal-regulatory functions of oxidized nitrogen forms, while the slower ones reflect the result of suppression of photoassimilate export from leaves by the anion.

  14. Tryptophan Residue Located at the Middle of Putative Transmembrane Domain 11 Is Critical for the Function of Organic Anion Transporting Polypeptide 2B1.

    Science.gov (United States)

    Bian, Jialin; Jin, Meng; Yue, Mei; Wang, Meiyu; Zhang, Hongjian; Gui, Chunshan

    2016-10-03

    Organic anion transporting polypeptide 2B1 (OATP2B1), which is highly expressed in enterocytes and hepatocytes could be a key determinant for the intestinal absorption and hepatic uptake of its substrates, most of which are amphipathic organic anions. Tryptophan residues may possess a multitude of functions for a transport protein through aromatic interactions, such as maintaining the proper protein structure, guiding the depth of membrane insertion, or interacting directly with substrates. There are totally six tryptophan residues in OATP2B1. However, little is known about their role in the function and expression of OATP2B1. Our results show that, while W272, W276, and W277 located at the border of extracellular loop 3 and transmembrane domain 6 exhibit a moderate effect on the surface expression of OATP2B1, W611 located at the middle of transmembrane domain 11 plays a critical role in the function of OATP2B1. The tryptophan-to-alanine mutation of W611 changes the kinetic characteristics of OATP2B1-mediated estrone-3-sulfate (E3S) transport radically, from a monophasic saturation curve (with K m and V max values being of 7.1 ± 1.1 μM and 182 ± 7 pmol/normalized mg/min, respectively) to a linear curve. Replacing alanine with a phenylalanine will rescue most of OATP2B1's function, suggesting that the aromatic side chain of residue 611 is very important. However, hydrogen-bond forming and positively charged groups at this position are not favorable. The important role of W611 is not substrate-dependent. Molecular modeling indicates that the side chain of W611 faces toward the substrate translocation pathway and might interact with substrates directly. Taken together, our findings reveal that W611 is critical for the function of OATP2B1.

  15. The Organic Anion-Transporting Peptide 2B1 Is Localized in the Basolateral Membrane of the Human Jejunum and Caco-2 Monolayers.

    Science.gov (United States)

    Keiser, Markus; Kaltheuner, Lars; Wildberg, Charlotte; Müller, Janett; Grube, Markus; Partecke, Lars Ivo; Heidecke, Claus-Dieter; Oswald, Stefan

    2017-09-01

    The organic anion-transporting polypeptide (OATP) 2B1 which is ubiquitously expressed in the human body is assumed to play an important role in the cellular uptake of many drugs. Although the expression and function of this solute carrier transporter is well characterized in the human liver and other tissues, little is known about its localization and functional relevance in the intestine. Thus, it was the aim of this study to investigate its localization and function in the human jejunum and in the frequently used intestinal Caco-2 cell line. The basolateral membrane of jejunal tissue from 6 individuals showed a significant enrichment of OATP2B1 (17-fold) and the known basolateral proteins ABCC3 and Na/K-ATPase compared to the apical membrane as derived from targeted proteomics analysis. On the contrary, apical localization could be confirmed for ABCB1, ABCC2, and PEPT1. Basolateral localization of OATP2B1 could also be verified in Caco-2 cells. Bidirectional transport studies with established OATP2B1 substrates (sulfasalazine and pravastatin) across freshly exercised human jejunum and Caco-2 cell monolayers demonstrated a markedly higher transport from the basal to the apical compartment than in the opposite direction. Our data provide evidence for a basolateral localization of OATP2B1 which may improve our understanding of intestinal drug absorption. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  16. Rational design of organoboron derivatives as chemosensors for fluoride and cyanide anions and charge transport and luminescent materials for organic light-emitting diodes.

    Science.gov (United States)

    Jin, Ruifa; Tang, Shanshan; Luo, Dongmei

    2014-03-01

    The interactions between chemosensors, donor-π-acceptor (D-π-A) dipolar organoboron derivatives, and different (CN⁻, F⁻, Cl⁻, and Br⁻) anions have been theoretically investigated using DFT approaches. Theoretical investigations have been performed to explore the optical, electronic, charge transport, and stability properties of organoboron derivatives as charge transport and luminescent materials for organic light emitting devices (OLEDs). It turned out that the unique selectivity of organoboron derivatives for F⁻/CN⁻ is ascribed to the formation of chemosensors complexes. The frontier molecular orbitals (FMOs) and local density of states analysis have turned out that the vertical electronic transitions of absorption and emission for chemosensors and their F⁻/CN⁻ complexes are characterized as intramolecular charge transfer (ICT). The formation of complexes has effect on the distribution of FMOs and the flowing direction of electronic density for vertical transition. The study of substituent effects suggests that the derivatives with thiophene (2), furan (3), and 1H-pyrrole (4) fragments, are expected to be promising candidates for ratiometric fluorescent fluoride and cyanide chemosensors as well as chromogenic chemosensors, whereas derivatives with pyridine (5) and pyrimidine (6) fragments can serve as chromogenic chemosensors only. Furthermore, all the derivatives are promising luminescent and hole transport materials and 2, 3, 5, and 6 can serve as electron transport materials for OLEDs.

  17. Comparison of the Predictability of Human Hepatic Clearance for Organic Anion Transporting Polypeptide Substrate Drugs Between Different In Vitro-In Vivo Extrapolation Approaches.

    Science.gov (United States)

    Izumi, Saki; Nozaki, Yoshitane; Komori, Takafumi; Takenaka, Osamu; Maeda, Kazuya; Kusuhara, Hiroyuki; Sugiyama, Yuichi

    2017-09-01

    Prediction of human pharmacokinetic profiles of drug candidates is an essential step toward first-in-human studies. However, it remains difficult to quantitatively predict hepatic clearance, particularly when hepatic uptake is mediated by transporter(s). Using 15 organic anion transporting polypeptide (OATP) substrate drugs, we tested 3 in vitro-in vivo extrapolation (IVIVE) approaches to predict overall hepatic intrinsic clearance in vivo (CL int,all,vivo ). IVIVE approaches involved metabolic intrinsic clearance in human liver microsomes (CL int,met ) with or without hepatocyte-to-buffer maximum unbound concentration ratio (K p,uu,max ) correction and uptake intrinsic clearance at 37°C (PS inf,37°C ) in human hepatocyte suspensions. K p,uu,max and PS inf,37°C values were determined in 2 hepatocyte batches, and all tested compounds showed temperature-dependent uptake, consistent with the fact of transporter-mediated uptake. CL int,met substantially underestimated CL int,all,vivo . By multiplying CL int,met by K p,uu,max values, the prediction performance was much improved; however, in vitro-in vivo correlation was poor. Among the IVIVE approaches, PS inf,37°C showed the most robust correlation with CL int,all,vivo , and one of the hepatocyte batches could predict CL int,all,vivo with a minimal empirical scaling factor. These results suggested IVIVE with hepatic uptake clearance determined in hepatocyte suspensions as one of the most practical approaches for predicting CL int,all,vivo of OATP substrate drugs. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  18. The effect of organic anion transporter 3 inhibitor probenecid on bumetanide levels in the brain: an integrated in vivo microdialysis study in the rat.

    Science.gov (United States)

    Donovan, Maria D; O'Brien, Fionn E; Boylan, Geraldine B; Cryan, John F; Griffin, Brendan T

    2015-04-01

    Recent data highlight the potential of bumetanide as a treatment for neonatal seizures and autism, as it facilitates the excitatory to inhibitory switch in gamma-aminobutyric acid signalling. This study examines the extent of blood-brain barrier (BBB) permeation of bumetanide, a key determinant of the efficacy of centrally acting drugs. Furthermore, the impact of efflux transporter organic anion transporter 3 (oat3) inhibition on bumetanide pharmacokinetics was investigated. Bumetanide levels in extracellular fluid (ECF) and plasma in the presence and absence of oat3 inhibitor probenecid were monitored using integrated microdialysis. Following a bumetanide bolus/continuous infusion of 10 mg/kg and 6 mg/kg/h, bumetanide was detected in hippocampal ECF at the estimated concentration of 131 ± 55 ng/ml. Plasma bumetanide levels were ∼20 mg/l at steady state. Coadministration of probenecid resulted in an increase in bumetanide levels in both ECF and plasma, indicating that oat3 inhibition influences the pharmacokinetics of bumetanide primarily in the periphery. Although bumetanide reached detectable levels in hippocampal ECF, bumetanide concentration in ECF was low relative to systemic concentration. Oat3 inhibition by probenecid resulted in increased bumetanide concentrations in brain and plasma. As an acute treatment in neonatal seizures, the bumetanide/probenecid combination may hold therapeutic potential. © 2014 Royal Pharmaceutical Society.

  19. Thyroxine (T4 Transfer from Blood to Cerebrospinal Fluid in Sheep Isolated Perfused Choroid Plexus: Role of Multidrug Resistance-Associated Proteins and Organic Anion Transporting Polypeptides

    Directory of Open Access Journals (Sweden)

    Kazem Zibara

    2017-05-01

    Full Text Available Thyroxine (T4 enters the brain either directly across the blood–brain barrier (BBB or indirectly via the choroid plexus (CP, which forms the blood–cerebrospinal fluid barrier (B-CSF-B. In this study, using isolated perfused CP of the sheep by single-circulation paired tracer and steady-state techniques, T4 transport mechanisms from blood into lateral ventricle CP has been characterized as the first step in the transfer across the B-CSF-B. After removal of sheep brain, the CPs were perfused with 125I-T4 and 14C-mannitol. Unlabeled T4 was applied during single tracer technique to assess the mode of maximum uptake (Umax and the net uptake (Unet on the blood side of the CP. On the other hand, in order to characterize T4 protein transporters, steady-state extraction of 125I-T4 was measured in presence of different inhibitors such as probenecid, verapamil, BCH, or indomethacin. Increasing the concentration of unlabeled-T4 resulted in a significant reduction in Umax%, which was reflected by a complete inhibition of T4 uptake into CP. In fact, the obtained Unet% decreased as the concentration of unlabeled-T4 increased. The addition of probenecid caused a significant inhibition of T4 transport, in comparison to control, reflecting the presence of a carrier mediated process at the basolateral side of the CP and the involvement of multidrug resistance-associated proteins (MRPs: MRP1 and MRP4 and organic anion transporting polypeptides (Oatp1, Oatp2, and Oatp14. Moreover, verapamil, the P-glycoprotein (P-gp substrate, resulted in ~34% decrease in the net extraction of T4, indicating that MDR1 contributes to T4 entry into CSF. Finally, inhibition in the net extraction of T4 caused by BCH or indomethacin suggests, respectively, a role for amino acid “L” system and MRP1/Oatp1 in mediating T4 transfer. The presence of a carrier-mediated transport mechanism for cellular uptake on the basolateral membrane of the CP, mainly P-gp and Oatp2, would account

  20. Casein Kinase 2 Is a Novel Regulator of the Human Organic Anion Transporting Polypeptide 1A2 (OATP1A2) Trafficking.

    Science.gov (United States)

    Chan, Ting; Cheung, Florence Shin Gee; Zheng, Jian; Lu, Xiaoxi; Zhu, Ling; Grewal, Thomas; Murray, Michael; Zhou, Fanfan

    2016-01-04

    Human organic anion transporting polypeptides (OATPs) mediate the influx of many important drugs into cells. Casein kinase 2 (CK2) is a critical protein kinase that phosphorylates >300 protein substrates and is dysregulated in a number of disease states. Among the CK2 substrates are several transporters, although whether this includes human OATPs has not been evaluated. The current study was undertaken to evaluate the regulation of human OATP1A2 by CK2. HEK-239T cells in which OATP1A2 was overexpressed were treated with CK2 specific inhibitors or transfected with CK2 specific siRNA, and the activity, expression, and subcellular trafficking of OATP1A2 was evaluated. CK2 inhibition decreased the uptake of the prototypic OATP1A2 substrate estrone-3-sulfate (E3S). Kinetic studies revealed that this was due to a decrease in the maximum velocity (Vmax) of E3S uptake, while the Michaelis constant was unchanged. The cell surface expression, but not the total cellular expression of OATP1A2, was impaired by CK2 inhibition and knockdown of the catalytic α-subunits of CK2. CK2 inhibition decreased the internalization of OATP1A2 via a clathrin-dependent pathway, decreased OATP1A2 recycling, and likely impaired OATP1A2 targeting to the cell surface. Consistent with these findings, CK2 inhibition also disrupted the colocalization of OATP1A2 and Rab GTPase (Rab)4-, Rab8-, and Rab9-positive endosomal and secretory vesicles. Taken together, CK2 has emerged as a novel regulator of the subcellular trafficking and stability of OATP1A2. Because OATP1A2 transports many molecules of physiological and pharmacological importance, the present data may inform drug selection in patients with diseases in which CK2 and OATP1A2 are dysregulated.

  1. Characterization of simvastatin acid uptake by organic anion transporting polypeptide 3A1 (OATP3A1) and influence of drug-drug interaction.

    Science.gov (United States)

    Atilano-Roque, Amandla; Joy, Melanie S

    2017-12-01

    Human organic anion transporting polypeptide 3A1 (OATP3A1) is predominately expressed in the heart. The ability of OATP3A1 to transport statins into cardiomyocytes is unknown, although other OATPs are known to mediate the uptake of statin drugs in liver. The pleiotropic effects and uptake of simvastatin acid were analyzed in primary human cardiomyocytes and HEK293 cells transfected with the OATP3A1 gene. Treatment with simvastatin acid reduced indoxyl sulfate-mediated reactive oxygen species and modulated OATP3A1 expression in cardiomyocytes and HEK293 cells transfected with the OATP3A1 gene. We observed a pH-dependent effect on OATP3A1 uptake, with more efficient simvastatin acid uptake at pH5.5 in HEK293 cells transfected with the OATP3A1 gene. The Michaelis-Menten constant (K m ) for simvastatin acid uptake by OATP3A1 was 0.017±0.002μM and the V max was 0.995±0.027fmol/min/10 5 cells. Uptake of simvastatin acid was significantly increased by known (benzylpenicillin and estrone-3-sulfate) and potential (indoxyl sulfate and cyclosporine) substrates of OATP3A1. In conclusion, the presence of OATP3A1 in cardiomyocytes suggests that this transporter may modulate the exposure of cardiac tissue to simvastatin acid due to its enrichment in cardiomyocytes. Increases in uptake of simvastatin acid by OATP3A1 when combined with OATP substrates suggest the potential for drug-drug interactions that could influence clinical outcomes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Natural and azido fatty acids inhibit phosphate transport and activate fatty acid anion uniport mediated by the mitochondrial phosphate carrier

    Czech Academy of Sciences Publication Activity Database

    Engstová, Hana; Žáčková, Markéta; Růžička, Michal; Meinhardt, A.; Hanuš, Jan; Krämer, R.; Ježek, Petr

    2001-01-01

    Roč. 276, č. 7 (2001), s. 4683-4691 ISSN 0021-9258 R&D Projects: GA ČR GA301/95/0620; GA ČR GA301/98/0568; GA MŠk ME 085; GA MŠk ME 389 Grant - others:US(US) Czechoslovak Science and Technology Program 94043 Institutional research plan: CEZ:AV0Z5011922 Keywords : phosphate transport * fatty acids Subject RIV: CE - Biochemistry Impact factor: 7.258, year: 2001

  3. Identification of amino acids essential for estrone-3-sulfate transport within transmembrane domain 2 of organic anion transporting polypeptide 1B1.

    Directory of Open Access Journals (Sweden)

    Nan Li

    Full Text Available As an important structure in membrane proteins, transmembrane domains have been found to be crucial for properly targeting the protein to cell membrane as well as carrying out transport functions in transporters. Computer analysis of OATP sequences revealed transmembrane domain 2 (TM2 is among those transmembrane domains that have high amino acid identities within different family members. In the present study, we identify four amino acids (Asp70, Phe73, Glu74, and Gly76 that are essential for the transport function of OATP1B1, an OATP member that is specifically expressed in the human liver. A substitution of these four amino acids with alanine resulted in significantly reduced transport activity. Further mutagenesis showed the charged property of Asp70 and Glu74 is critical for proper function of the transporter protein. Comparison of the kinetic parameters indicated that Asp70 is likely to interact with the substrate while Glu74 may be involved in stabilizing the binding site through formation of a salt-bridge. The aromatic ring structure of Phe73 seems to play an important role because substitution of Phe73 with tyrosine, another amino acid with a similar structure, led to partially restored transport function. On the other hand, replacement of Gly76 with either alanine or valine could not recover the function of the transporter. Considering the nature of a transmembrane helix, we proposed that Gly76 may be important for maintaining the proper structure of the protein. Interestingly, when subjected to transport function analysis of higher concentration of esteone-3-sulfate (50 µM that corresponds to the low affinity binding site of OATP1B1, mutants of Phe73, Glu74, and Gly76 all showed a transport function that is comparable to that of the wild-type, suggesting these amino acids may have less impact on the low affinity component of esteone-3-sulfate within OATP1B1, while Asp 70 seems to be involved in the interaction of both sites.

  4. Comparative effects of nodularin and microcystin-LR in zebrafish: 1. Uptake by organic anion transporting polypeptide Oatp1d1 (Slco1d1).

    Science.gov (United States)

    Faltermann, Susanne; Prétôt, René; Pernthaler, Jakob; Fent, Karl

    2016-02-01

    Microcystin-LR (MC-LR) and nodularin are hepatotoxins produced by several cyanobacterial species. Their toxicity is based on active cellular uptake and subsequent inhibition of protein phosphatases PP1/2A, leading to hyperphosphorylation and cell death. To date, uptake of MC-LR and nodularin in fish is poorly understood. Here, we investigated the role of the organic anion transporting polypeptide Oatp1d1 in zebrafish (drOatp1d1, Slco1d1) in cellular uptake in zebrafish. We stably transfected CHO and HEK293 cell lines expressing drOatp1d1. In both transfectants, uptake of MC-LR and nodularin was demonstrated by competitive inhibition of uptake with fluorescent substrate lucifer yellow. Direct uptake of MC-LR was demonstrated by immunostaining, and indirectly by the high cytotoxicity in stable transfectants. By means of a synthesized fluorescent labeled MC-LR derivative, direct uptake was further confirmed in HEK293 cells expressing drOatp1d1. Additionally, uptake and toxicity was investigated in the permanent zebrafish liver cell line ZFL. These cells had only a low relative abundance of drOatp1d1, drOatp2b1 and drOatp1f transcripts, which correlated with the lack of MC-LR induced cytotoxicity and transcriptional changes of genes indicative of endoplasmic reticulum stress, a known effect of this toxin. Our study demonstrates that drOatp1d1 functions as an uptake transporter for both MC-LR and nodularin in zebrafish. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Solute carrier organic anion transporter family member 4A1 (SLCO4A1) as a prognosis marker of colorectal cancer.

    Science.gov (United States)

    Ban, Myung Jin; Ji, Sang Hee; Lee, Chi-Kyu; Bae, Sang Byung; Kim, Han Jo; Ahn, Tae Sung; Lee, Moon Soo; Baek, Moo-Jun; Jeong, Dongjun

    2017-08-01

    Solute carrier organic anion transporter family member 4A1 (SLCO4A1) is involved in the transport of various compounds, including sugars, bile salts, organic acids, metal ions, amine compounds, and estrogen. SLCO4A1 is highly expressed in several cancers and a gender bias has been observed in colorectal cancer (CRC). We investigated SLCO4A1 expression, its prognostic value in patients with CRC, and its role in CRC cell proliferation and metastasis. SLCO4A1 expression was assessed by immunohistochemistry (IHC) on specimens from 84 patients with CRC. The association of SLCO4A1 expression with clinicopathological features was examined. To confirm the biological role of SLCO4A1 in CRC, four CRC cell lines expressing SLCO4A1 were used and SLCO4A1 expression was knocked down by siRNA. Cell proliferation, MTT, migration, invasion, and semisolid agar colony formation assays were performed. SLCO4A1 was overexpressed in 32% of the CRC samples. SLCO4A1 overexpression and pathologic T stage were independent prognostic factors of decreased survival (P = 0.021). Kaplan-Meier analysis indicated a decreased cumulative survival for patients highly expressing SLCO4A1 compared to patients showing low SLCO4A1 expression (Log-rank test, P = 0.025). In cell lines, SLCO4A1 knockdown resulted in a significant decrease of viability, invasion, and migration when compared to control cells. Semisolid colony formation assay indicated that SLCO4A1-knocked down cells presented poor carcinogenic abilities compared to control cells. SLCO4A1 may be a valuable marker of poor prognostic for CRC. Furthermore, SLCO4A1 plays an important role in CRC cell proliferation, migration, invasion, and carcinogenesis.

  6. Lack of Contribution of Multidrug Resistance-associated Protein and Organic Anion-transporting Polypeptide to Pharmacokinetics of Regorafenib, a Novel Multi-Kinase Inhibitor, in Rats.

    Science.gov (United States)

    Hotta, Kazuo; Ueyama, Jun; Tatsumi, Yasuaki; Tsukiyama, Ikuto; Sugiura, Yuka; Saito, Hiroko; Matsuura, Katsuhiko; Hasegawa, Takaaki

    2015-09-01

    We investigated whether hepatic multidrug resistance-associated protein 2 (ABCC2) is involved in the hepatobiliary excretion of regorafenib, a novel multi-kinase inhibitor, using Sprague-Dawley (SD) rats and Eisai hyperbilirubinemic rats (EHBR) lacking the efflux transporter ABCC2. The involvement of organic anion-transporting polypeptide 1 (OATP1; OATP in humans) and OATP2 in the hepatic uptake of regorafenib and their protein levels in the liver were also investigated in the two rat groups. When regorafenib (5 mg/kg) was administered intravenously, the plasma concentrations of regorafenib were higher in EHBR than those in SD rats. However, the slope of the plasma concentration-time curves was the same for the two groups. Although the apparent biliary clearance of regorafenib in EHBR was lower than that of SD rats, no significant difference in the biliary excretion rate was observed between them, suggesting that regorafenib is not a substrate for ABCC2 and is not excreted into bile by ABCC2. It was also found that the contribution of biliary excretion to the systemic elimination of regorafenib is small. The protein-binding profiles of regorafenib were found to be linear in both rat groups. The binding potency, which was very high in both rat groups (>99.5%), was significantly higher in EHBR than that in SD rats. No significant differences in the plasma concentrations of unbound regorafenib were observed between the two rat groups, suggesting that the differences observed in the pharmacokinetic behaviors of regorafenib between the two rat groups were due to differences in protein-binding. When the protein levels of hepatic OATP1 and OATP2 were measured by immunoblot analysis, the expression of both transporters in EHBR was less than 40% of that in SD rats. The present results suggest that regorafenib is not a substrate for OATP1 and OATP2. These findings suggest the possibility that ABCC2-mediated hepatobiliary excretion and OATP1/OATP2-mediated hepatic uptake do

  7. anion dependence

    Indian Academy of Sciences (India)

    SUMAN Das

    batteries with high ene- rgy storage capability is often used as attractive power sources. However, use of Li. + battery in large scale poses some challenges in automobile industry. The limitation is mainly due to their ...... transport properties of the LiPF6 doped 1-ethyl-2,3- dimethyl-imidazolium hexafluorophosphate ionic liq-.

  8. The glutamate aspartate transporter (GLAST) mediates L-glutamate-stimulated ascorbate-release via swelling-activated anion channels in cultured neonatal rodent astrocytes.

    Science.gov (United States)

    Lane, Darius J R; Lawen, Alfons

    2013-03-01

    Vitamin C (ascorbate) plays important neuroprotective and neuromodulatory roles in the mammalian brain. Astrocytes are crucially involved in brain ascorbate homeostasis and may assist in regenerating extracellular ascorbate from its oxidised forms. Ascorbate accumulated by astrocytes can be released rapidly by a process that is stimulated by the excitatory amino acid, L-glutamate. This process is thought to be neuroprotective against excitotoxicity. Although of potential clinical interest, the mechanism of this stimulated ascorbate-release remains unknown. Here, we report that primary cultures of mouse and rat astrocytes release ascorbate following initial uptake of dehydroascorbate and accumulation of intracellular ascorbate. Ascorbate-release was not due to cellular lysis, as assessed by cellular release of the cytosolic enzyme lactate dehydrogenase, and was stimulated by L-glutamate and L-aspartate, but not the non-excitatory amino acid L-glutamine. This stimulation was due to glutamate-induced cellular swelling, as it was both attenuated by hypertonic and emulated by hypotonic media. Glutamate-stimulated ascorbate-release was also sensitive to inhibitors of volume-sensitive anion channels, suggesting that the latter may provide the conduit for ascorbate efflux. Glutamate-stimulated ascorbate-release was not recapitulated by selective agonists of either ionotropic or group I metabotropic glutamate receptors, but was completely blocked by either of two compounds, TFB-TBOA and UCPH-101, which non-selectively and selectively inhibit the glial Na(+)-dependent excitatory amino acid transporter, GLAST, respectively. These results suggest that an impairment of astrocytic ascorbate-release may exacerbate neuronal dysfunction in neurodegenerative disorders and acute brain injury in which excitotoxicity and/or GLAST deregulation have been implicated.

  9. Transport behaviors of anionic azo dyes at interface between surfactant-modified flax shives and aqueous solution: Synchrotron infrared and adsorption studies

    International Nuclear Information System (INIS)

    Wang, Wenxia; Huang, Guohe; An, Chunjiang; Xin, Xiaying; Zhang, Yan; Liu, Xia

    2017-01-01

    Highlights: • Surfactant modified flax shives for removing anionic azo dyes. • The equilibrium and kinetic studies for the adsorption of anionic azo dyes. • The migration patterns of dye pollutants at flax shive-water interface. • New insights from synchrotron infrared-assisted characterization. • Potential as biomass adsorbent for the removal of dyes from wastewater. - Abstract: From the viewpoint of sustainability, biomass adsorbent has a high potential in pollution control and there is an emerging interest to investigate the behaviors of pollutants at the interface between biomass adsorbent and solution. This study investigated the performance of cetyltrimethylammonium bromide surfactant-modified flax shives (MFS) for removal of anionic azo dyes from aqueous solution. The equilibrium and kinetic analysis for the adsorption of Acid Orange 7 (AO-7), Acid Red 18 (AR-18) and Acid Black 1 (AB-1) on MFS were conducted. The surface of MFS was characterized by synchrotron infrared and SEM analysis. The absorbed amount of three anionic azo dyes varied with the change of adsorbent dosage, pH and ionic strength. The adsorption isotherm data well fit to the Langmuir model. The adsorption process followed the pseudo-second-order kinetics and the liquid film diffusion models. Thermodynamic studies indicated that the adsorption of three anionic azo dyes was spontaneous. The adsorption of AR-18 and AB-1 onto MFS was endothermic while the adsorption of AO-7 was exothermic. The results can help better understand the behaviors of organic pollutants at biomass adsorbent-water interface. They also present the potential of using MFS as a suitable adsorbent for the removal of anionic azo dyes from wastewater.

  10. Transport behaviors of anionic azo dyes at interface between surfactant-modified flax shives and aqueous solution: Synchrotron infrared and adsorption studies

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wenxia [MOE Key Laboratory of Resources and Environmental Systems Optimization, Institute for Energy, Environment and Sustainability Research, UR-NCEPU, North China Electric Power University, Beijing, 102206 (China); Huang, Guohe, E-mail: huang@iseis.org [MOE Key Laboratory of Resources and Environmental Systems Optimization, Institute for Energy, Environment and Sustainability Research, UR-NCEPU, North China Electric Power University, Beijing, 102206 (China); An, Chunjiang; Xin, Xiaying [Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, S4S 0A2 (Canada); Zhang, Yan [MOE Key Laboratory of Resources and Environmental Systems Optimization, Institute for Energy, Environment and Sustainability Research, UR-NCEPU, North China Electric Power University, Beijing, 102206 (China); Liu, Xia [Canadian Light Source, Saskatoon, S7N 2V3 (Canada)

    2017-05-31

    Highlights: • Surfactant modified flax shives for removing anionic azo dyes. • The equilibrium and kinetic studies for the adsorption of anionic azo dyes. • The migration patterns of dye pollutants at flax shive-water interface. • New insights from synchrotron infrared-assisted characterization. • Potential as biomass adsorbent for the removal of dyes from wastewater. - Abstract: From the viewpoint of sustainability, biomass adsorbent has a high potential in pollution control and there is an emerging interest to investigate the behaviors of pollutants at the interface between biomass adsorbent and solution. This study investigated the performance of cetyltrimethylammonium bromide surfactant-modified flax shives (MFS) for removal of anionic azo dyes from aqueous solution. The equilibrium and kinetic analysis for the adsorption of Acid Orange 7 (AO-7), Acid Red 18 (AR-18) and Acid Black 1 (AB-1) on MFS were conducted. The surface of MFS was characterized by synchrotron infrared and SEM analysis. The absorbed amount of three anionic azo dyes varied with the change of adsorbent dosage, pH and ionic strength. The adsorption isotherm data well fit to the Langmuir model. The adsorption process followed the pseudo-second-order kinetics and the liquid film diffusion models. Thermodynamic studies indicated that the adsorption of three anionic azo dyes was spontaneous. The adsorption of AR-18 and AB-1 onto MFS was endothermic while the adsorption of AO-7 was exothermic. The results can help better understand the behaviors of organic pollutants at biomass adsorbent-water interface. They also present the potential of using MFS as a suitable adsorbent for the removal of anionic azo dyes from wastewater.

  11. Anion binding in biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Feiters, Martin C [Department of Organic Chemistry, Institute for Molecules and Materials, Faculty of Science, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands); Meyer-Klaucke, Wolfram [EMBL Hamburg Outstation at DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Kostenko, Alexander V; Soldatov, Alexander V [Faculty of Physics, Southern Federal University, Sorge 5, Rostov-na-Donu, 344090 (Russian Federation); Leblanc, Catherine; Michel, Gurvan; Potin, Philippe [Centre National de la Recherche Scientifique and Universite Pierre et Marie Curie Paris-VI, Station Biologique de Roscoff, Place Georges Teissier, BP 74, F-29682 Roscoff cedex, Bretagne (France); Kuepper, Frithjof C [Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban, Argyll PA37 1QA, Scotland (United Kingdom); Hollenstein, Kaspar; Locher, Kaspar P [Institute of Molecular Biology and Biophysics, ETH Zuerich, Schafmattstrasse 20, Zuerich, 8093 (Switzerland); Bevers, Loes E; Hagedoorn, Peter-Leon; Hagen, Wilfred R, E-mail: m.feiters@science.ru.n [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands)

    2009-11-15

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L{sub 3} (2p{sub 3/2}) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  12. Anion binding in biological systems

    International Nuclear Information System (INIS)

    Feiters, Martin C; Meyer-Klaucke, Wolfram; Kostenko, Alexander V; Soldatov, Alexander V; Leblanc, Catherine; Michel, Gurvan; Potin, Philippe; Kuepper, Frithjof C; Hollenstein, Kaspar; Locher, Kaspar P; Bevers, Loes E; Hagedoorn, Peter-Leon; Hagen, Wilfred R

    2009-01-01

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L 3 (2p 3/2 ) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  13. Anion binding in biological systems

    Science.gov (United States)

    Feiters, Martin C.; Meyer-Klaucke, Wolfram; Kostenko, Alexander V.; Soldatov, Alexander V.; Leblanc, Catherine; Michel, Gurvan; Potin, Philippe; Küpper, Frithjof C.; Hollenstein, Kaspar; Locher, Kaspar P.; Bevers, Loes E.; Hagedoorn, Peter-Leon; Hagen, Wilfred R.

    2009-11-01

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L3 (2p3/2) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  14. Transport behaviors of anionic azo dyes at interface between surfactant-modified flax shives and aqueous solution: Synchrotron infrared and adsorption studies

    Science.gov (United States)

    Wang, Wenxia; Huang, Guohe; An, Chunjiang; Xin, Xiaying; Zhang, Yan; Liu, Xia

    2017-05-01

    From the viewpoint of sustainability, biomass adsorbent has a high potential in pollution control and there is an emerging interest to investigate the behaviors of pollutants at the interface between biomass adsorbent and solution. This study investigated the performance of cetyltrimethylammonium bromide surfactant-modified flax shives (MFS) for removal of anionic azo dyes from aqueous solution. The equilibrium and kinetic analysis for the adsorption of Acid Orange 7 (AO-7), Acid Red 18 (AR-18) and Acid Black 1 (AB-1) on MFS were conducted. The surface of MFS was characterized by synchrotron infrared and SEM analysis. The absorbed amount of three anionic azo dyes varied with the change of adsorbent dosage, pH and ionic strength. The adsorption isotherm data well fit to the Langmuir model. The adsorption process followed the pseudo-second-order kinetics and the liquid film diffusion models. Thermodynamic studies indicated that the adsorption of three anionic azo dyes was spontaneous. The adsorption of AR-18 and AB-1 onto MFS was endothermic while the adsorption of AO-7 was exothermic. The results can help better understand the behaviors of organic pollutants at biomass adsorbent-water interface. They also present the potential of using MFS as a suitable adsorbent for the removal of anionic azo dyes from wastewater.

  15. Anion conductance of the human red cell is carried by a maxi-anion channel

    DEFF Research Database (Denmark)

    Glogowska, Edyta; Dyrda, Agnieszka; Cueff, Anne

    2010-01-01

    Historically, the anion transport through the human red cell membrane has been perceived to be mediated by Band 3, in the two-component concept with the large electroneutral anion exchange accompanied by the conductance proper, which dominated the total membrane conductance. The status of anion...... that the diversity of anionic channel activities recorded in human erythrocytes corresponds to different kinetic modalities of a unique type of maxi-anion channel with multiple conductance levels and probably multiple gating properties and pharmacology, depending on conditions. It demonstrates the role of activator...... played by serum in the recruitment of multiple new conductance levels showing very complex kinetics and gating properties upon serum addition. These channels, which seem to be dormant under normal physiological conditions, are potentially activable and could confer a far higher anion conductance...

  16. Sex-Differences in Renal Expression of Selected Transporters and Transcription Factors in Lean and Obese Zucker Spontaneously Hypertensive Fatty Rats

    Directory of Open Access Journals (Sweden)

    Andrea Babelova

    2015-01-01

    Full Text Available The aim of this study was to identify sex-dependent expression of renal transporter mRNA in lean and obese Zucker spontaneously hypertensive fatty (ZSF1 rats and to investigate the interaction of the most altered transporter, organic anion transporter 2 (Oat2, with diabetes-relevant metabolites and drugs. Higher incidence of glomerulosclerosis, tubulointerstitial fibrosis, and protein casts in Bowman’s space and tubular lumen was detected by PAS staining in obese male compared to female ZSF1 rats. Real-time PCR on RNA isolated from kidney cortex revealed that Sglt1-2, Oat1-3, and Oct1 were higher expressed in kidneys of lean females. Oct2 and Mrp2 were higher expressed in obese males. Renal mRNA levels of transporters were reduced with diabetic nephropathy in females and the expression of transcription factors Hnf1β and Hnf4α in both sexes. The highest difference between lean and obese ZSF1 rats was found for Oat2. Therefore, we have tested the interaction of human OAT2 with various substances using tritium-labeled cGMP. Human OAT2 showed no interaction with diabetes-related metabolites, diabetic drugs, and ACE-inhibitors. However, OAT2-dependent uptake of cGMP was inhibited by furosemide. The strongly decreased expression of Oat2 and other transporters in female diabetic ZSF1 rats could possibly impair renal drug excretion, for example, of furosemide.

  17. Advances in anion supramolecular chemistry: from recognition to chemical applications.

    Science.gov (United States)

    Evans, Nicholas H; Beer, Paul D

    2014-10-27

    Since the start of this millennium, remarkable progress in the binding and sensing of anions has been taking place, driven in part by discoveries in the use of hydrogen bonding, as well as the previously under-exploited anion-π interactions and halogen bonding. However, anion supramolecular chemistry has developed substantially beyond anion recognition, and now encompasses a diverse range of disciplines. Dramatic advance has been made in the anion-templated synthesis of macrocycles and interlocked molecular architectures, while the study of transmembrane anion transporters has flourished from almost nothing into a rapidly maturing field of research. The supramolecular chemistry of anions has also found real practical use in a variety of applications such as catalysis, ion extraction, and the use of anions as stimuli for responsive chemical systems. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Pu Anion Exchange Process Intensification

    Energy Technology Data Exchange (ETDEWEB)

    Taylor-Pashow, Kathryn M. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-10-06

    This research is focused on improving the efficiency of the anion exchange process for purifying plutonium. While initially focused on plutonium, the technology could also be applied to other ion-exchange processes. Work in FY17 focused on the improvement and optimization of porous foam columns that were initially developed in FY16. These foam columns were surface functionalized with poly(4-vinylpyridine) (PVP) to provide the Pu specific anion-exchange sites. Two different polymerization methods were explored for maximizing the surface functionalization with the PVP. The open-celled polymeric foams have large open pores and large surface areas available for sorption. The fluid passes through the large open pores of this material, allowing convection to be the dominant mechanism by which mass transport takes place. These materials generally have very low densities, open-celled structures with high cell interconnectivity, small cell sizes, uniform cell size distributions, and high structural integrity. These porous foam columns provide advantages over the typical porous resin beads by eliminating the slow diffusion through resin beads, making the anion-exchange sites easily accessible on the foam surfaces. The best performing samples exceeded the Pu capacity of the commercially available resin, and also offered the advantage of sharper elution profiles, resulting in a more concentrated product, with less loss of material to the dilute heads and tails cuts. An alternate approach to improving the efficiency of this process was also explored through the development of a microchannel array system for performing the anion exchange.

  19. Effect of humic acid on uranium(VI) retention and transport through quartz columns with varying pH and anion type.

    Science.gov (United States)

    Du, Liang; Li, Shicheng; Li, Xiaolong; Wang, Ping; Huang, Zhaoya; Tan, Zhaoyi; Liu, Chunli; Liao, Jiali; Liu, Ning

    2017-10-01

    Humic acid (HA) 1 is ubiquitous in the environment and is an important factor in the migration behavior of U(VI) in the geological medium. The present work investigated the effect of HA on the migration behavior of U(VI) using quartz column experiments at different pH values and in the presence of various anions. The U(VI) adsorption characteristics and speciation were also studied to illuminate further the migration behavior of U(VI). Our results indicated that, at pH 6.0, HA slightly increased the migration velocity of U(VI) during the initial phase and reduced the quantity of eluted U(VI) because of the formation of HA-U(VI). The relative concentration (c/c 0 ) of U(VI)was higher in the HA-U system at pH 8.0 than that at pH 5.0 because of the higher solubility of HA in basic solutions and the difference in charge of HA-U(VI). In the U-HA-anion system at pH 6.0, the breakthrough pore volumes (PVs 2 ) of U(VI) in electrolytes containing Cl - and SO 4 2- anions (PV = 8) are much higher than for solutions containing phosphate (PV = 3), while the HA migration behavior was not significantly affected by the type of anion. Thus, the fast migration of U(VI) under HA and phosphate was attributed to phosphate rather than HA. This result suggests that phosphate should be given more attention in predictions of U(VI) migration, especially in regions with high groundwater phosphate content. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Interactions with selected drug renal transporters and transporter-mediated cytotoxicity in antiviral agents from the group of acyclic nucleoside phosphonates

    Czech Academy of Sciences Publication Activity Database

    Mandíková, J.; Volková, M.; Pávek, P.; Česnek, Michal; Janeba, Zlatko; Kubíček, V.; Trejtnar, F.

    2013-01-01

    Roč. 311, č. 3 (2013), s. 135-146 ISSN 0300-483X Institutional support: RVO:61388963 Keywords : hOAT1 * hCNTs * MDR1 * BCRP * nephrotoxicity * transmembrane transport Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 3.745, year: 2013

  1. Lesinurad, a novel, oral compound for gout, acts to decrease serum uric acid through inhibition of urate transporters in the kidney.

    Science.gov (United States)

    Miner, Jeffrey; Tan, Philip K; Hyndman, David; Liu, Sha; Iverson, Cory; Nanavati, Payal; Hagerty, David T; Manhard, Kimberly; Shen, Zancong; Girardet, Jean-Luc; Yeh, Li-Tain; Terkeltaub, Robert; Quart, Barry

    2016-10-03

    Excess body burden of uric acid promotes gout. Diminished renal clearance of uric acid causes hyperuricemia in most patients with gout, and the renal urate transporter (URAT)1 is important for regulation of serum uric acid (sUA) levels. The URAT1 inhibitors probenecid and benzbromarone are used as gout therapies; however, their use is limited by drug-drug interactions and off-target toxicity, respectively. Here, we define the mechanism of action of lesinurad (Zurampic®; RDEA594), a novel URAT1 inhibitor, recently approved in the USA and Europe for treatment of chronic gout. sUA levels, fractional excretion of uric acid (FE UA ), lesinurad plasma levels, and urinary excretion of lesinurad were measured in healthy volunteers treated with lesinurad. In addition, lesinurad, probenecid, and benzbromarone were compared in vitro for effects on urate transporters and the organic anion transporters (OAT)1 and OAT3, changes in mitochondrial membrane potential, and human peroxisome proliferator-activated receptor gamma (PPARγ) activity. After 6 hours, a single 200-mg dose of lesinurad elevated FE UA 3.6-fold (p uric acid. Lesinurad also has a favorable selectivity and safety profile, consistent with an important role in sUA-lowering therapy for patients with gout.

  2. Transport properties of anion exchange membranes in contact with organic ions. Part 2. Influence of the size of the aromatic chain; Proprietes de transport de membranes echangeuses d'anions en presence d'ions organiques. Partie 2. Influence de la taille de la chaine aromatique

    Energy Technology Data Exchange (ETDEWEB)

    Delimi, R. [Lab. de Traitement des eaux, Institut de Chimie, Universite de Badji Mokhtar, Annaba (Algeria); Sandeaux, J.; Sandeaux, R.; Pourcelly, G. [Montpellier-2 Univ., Institut Europeen des Mambranes, UMR 5635, 34 (France)

    2000-12-01

    Electrodialysis (process using ion exchange membranes and an electric field) is used for the treatment of waters and industrial effluents. In this work, the physico-chemical properties of an anion exchange membrane (ADS, Solvay) were studied in aqueous solutions containing both a mineral salt (10{sup -1} M NaCl) and an organic salt (10{sup -2} to 10{sup -1} M). The organic salt was a sodium carboxylate or sulfonate bearing one or two aromatic rings. Measurements of ion exchange, water content, electric resistance, self-diffusion and electro-diffusion fluxes were performed. According to the concentration, the organic anions with highly hydrophobic character can induce a poisoning of the membrane. (authors)

  3. Determination of Hydraulic and Transport Parameters of Organic Chemical and Inorganic Anions Solutes for Unfractured Cores of Berea Sandstone Using a Hydraulic Coreholder

    Science.gov (United States)

    Blanford, W. J.; Neil, L.

    2017-12-01

    To better evaluate the potential for toxic organic chemicals to migrate upward through the rock strata from hydraulic fracturing zones and into groundwater resources, a series of miscible displacement solute transport studies of cores of Berea Sandstone have been conducted using hydrostatic core holder. These tests involved passing aqueous solutions with natural background level of salts using a high pressure LC pump through 2 in wide by 3 in long unfractured cores held within the holder. Relative solute transport of 100 to 500ml pulses of target solutes including a series of chlorinated solvents and methylated benzenes was measured through in-line UV and fluorescence detectors and manual sampling and analysis with GCMS. The results found these sandstones to result in smooth ideal shaped breakthrough curves. Analysis with 1D transport models (CXTFIT) of the results found strong correlation with chemical parameters (diffusion coefficients, aqueous solubility, and octanol-water partitioning coefficients) showing that these parameter and QSPR relationships can be used to make accurate predictions for such a system. In addition to the results of the studies, lessons learned from this novel use of a coreholder for evaluation of porosity, water-saturated permeability, and solute transport of these sandstones (K = 1.5cm/day) and far less permeable sandstones samples (K = 0.15 cm/yr) from a hydraulic fracturing site in central Pennsylvania will be presented.

  4. Anion-π catalysis.

    Science.gov (United States)

    Zhao, Yingjie; Beuchat, César; Domoto, Yuya; Gajewy, Jadwiga; Wilson, Adam; Mareda, Jiri; Sakai, Naomi; Matile, Stefan

    2014-02-05

    The introduction of new noncovalent interactions to build functional systems is of fundamental importance. We here report experimental and theoretical evidence that anion-π interactions can contribute to catalysis. The Kemp elimination is used as a classical tool to discover conceptually innovative catalysts for reactions with anionic transition states. For anion-π catalysis, a carboxylate base and a solubilizer are covalently attached to the π-acidic surface of naphthalenediimides. On these π-acidic surfaces, transition-state stabilizations up to ΔΔGTS = 31.8 ± 0.4 kJ mol(-1) are found. This value corresponds to a transition-state recognition of KTS = 2.7 ± 0.5 μM and a catalytic proficiency of 3.8 × 10(5) M(-1). Significantly increasing transition-state stabilization with increasing π-acidity of the catalyst, observed for two separate series, demonstrates the existence of "anion-π catalysis." In sharp contrast, increasing π-acidity of the best naphthalenediimide catalysts does not influence the more than 12 000-times weaker substrate recognition (KM = 34.5 ± 1.6 μM). Together with the disappearance of Michaelis-Menten kinetics on the expanded π-surfaces of perylenediimides, this finding supports that contributions from π-π interactions are not very important for anion-π catalysis. The linker between the π-acidic surface and the carboxylate base strongly influences activity. Insufficient length and flexibility cause incompatibility with saturation kinetics. Moreover, preorganizing linkers do not improve catalysis much, suggesting that the ideal positioning of the carboxylate base on the π-acidic surface is achieved by intramolecular anion-π interactions rather than by an optimized structure of the linker. Computational simulations are in excellent agreement with experimental results. They confirm, inter alia, that the stabilization of the anionic transition states (but not the neutral ground states) increases with the π-acidity of the

  5. Overexpression of Interleukin-4 in the Thyroid of Transgenic Mice Upregulates the Expression of Duox1 and the Anion Transporter Pendrin.

    Science.gov (United States)

    Eskalli, Zineb; Achouri, Younes; Hahn, Stephan; Many, Marie-Christine; Craps, Julie; Refetoff, Samuel; Liao, Xiao-Hui; Dumont, Jacques E; Van Sande, Jacqueline; Corvilain, Bernard; Miot, Françoise; De Deken, Xavier

    2016-10-01

    The dual oxidases (Duox) are involved in hydrogen peroxide generation, which is essential for thyroid hormone synthesis, and therefore they are markers of thyroid function. During inflammation, cytokines upregulate DUOX gene expression in the airway and the intestine, suggesting a role for these proteins in innate immunity. It was previously demonstrated that interleukin-4 (IL-4) upregulates DUOX gene expression in thyrocytes. Although the role of IL-4 in autoimmune thyroid diseases has been studied extensively, the effects of IL-4 on thyroid physiology remain largely unknown. Therefore, a new animal model was generated to study the impact of IL-4 on thyroid function. Transgenic (Thyr-IL-4) mice with thyroid-targeted expression of murine IL-4 were generated. Transgene expression was verified at the mRNA and protein level in thyroid tissues and primary cultures. The phenotype of the Thyr-IL-4 animals was characterized by measuring serum thyroxine (T4) and thyrotropin levels and performing thyroid morphometric analysis, immunohistochemistry, whole transcriptome sequencing, quantitative reverse transcription polymerase chain reaction, and ex vivo thyroid function assays. Thyrocytes from two Thyr-IL-4 mouse lines (#30 and #52) expressed IL-4, which was secreted into the extracellular space. Although 10-month-old transgenic animals had T4 and thyrotropin serum levels in the normal range, they had altered thyroid follicular structure with enlarged follicles composed of elongated thyrocytes containing numerous endocytic vesicles. These follicles were positive for T4 staining the colloid, indicating their capacity to produce thyroid hormones. RNA profiling of Thyr-IL-4 thyroid samples revealed modulation of multiple genes involved in inflammation, while no major leukocyte infiltration could be detected. Upregulated expression of Duox1, Duoxa1, and the pendrin anion exchanger gene (Slc26a4) was detected. In contrast, the iodide symporter gene Slc5a5 was markedly

  6. Differential Mechanisms of Tenofovir and Tenofovir Disoproxil Fumarate Cellular Transport and Implications for Topical Preexposure Prophylaxis.

    Science.gov (United States)

    Taneva, Ekaterina; Crooker, Kerry; Park, Sung Hyun; Su, Jonathan T; Ott, Adina; Cheshenko, Natalia; Szleifer, Igal; Kiser, Patrick F; Frank, Bruce; Mesquita, Pedro M M; Herold, Betsy C

    2015-12-28

    Intravaginal rings releasing tenofovir (TFV) or its prodrug, tenofovir disoproxil fumarate (TDF), are being evaluated for HIV and herpes simplex virus (HSV) prevention. The current studies were designed to determine the mechanisms of drug accumulation in human vaginal and immune cells. The exposure of vaginal epithelial or T cells to equimolar concentrations of radiolabeled TDF resulted in over 10-fold higher intracellular drug levels than exposure to TFV. Permeability studies demonstrated that TDF, but not TFV, entered cells by passive diffusion. TDF uptake was energy independent but its accumulation followed nonlinear kinetics, and excess unlabeled TDF inhibited radiolabeled TDF uptake in competition studies. The carboxylesterase inhibitor bis-nitrophenyl phosphate reduced TDF uptake, suggesting saturability of intracellular carboxylesterases. In contrast, although TFV uptake was energy dependent, no competition between unlabeled and radiolabeled TFV was observed, and the previously identified transporters, organic anion transporters (OATs) 1 and 3, were not expressed in human vaginal or T cells. The intracellular accumulation of TFV was reduced by the addition of endocytosis inhibitors, and this resulted in the loss of TFV antiviral activity. Kinetics of drug transport and metabolism were monitored by quantifying the parent drugs and their metabolites by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Results were consistent with the identified mechanisms of transport, and the exposure of vaginal epithelial cells to equimolar concentrations of TDF compared to TFV resulted in ∼40-fold higher levels of the active metabolite, tenofovir diphosphate. Together, these findings indicate that substantially lower concentrations of TDF than TFV are needed to protect cells from HIV and HSV-2. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  7. Transport of free 211At and 125I- in thyroid epithelial cells: effects of anion channel blocker 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid on apical efflux and cellular retention

    International Nuclear Information System (INIS)

    Lindencrona, Ulrika; Forssell-Aronsson, Eva; Nilsson, Mikael

    2007-01-01

    Introduction: Astatine ( 211 At; α-emitter; t 1/2 =7.21 h) shares several features with its halogen neighbour iodine. In the present study, we investigated whether 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) can be used to increase the cellular retention time of 211 At and radioiodide in thyroid epithelial cells. Methods: The transepithelial transport and cellular uptake of 211 At and 125 I - were studied simultaneously in porcine thyrocytes cultured in bicameral chambers. The cells were prestimulated with thyroid-stimulating hormone (TSH) or epidermal growth factor (EGF) for 48 h. In addition, the acute effects of DIDS and forskolin were investigated. Results: The transepithelial transport of both radionuclides was stimulated by TSH and down-regulated by EGF. DIDS rapidly reduced the efflux and increased the cellular content of 125 I - in control and TSH-stimulated cells, whereas DIDS had no effect on 125 I - transport in EGF-treated cells. DIDS blocked the 211 At efflux only in TSH-stimulated cells. Unexpectedly, DIDS caused an accelerated efflux of 211 At in both control and EGF-stimulated cells and, furthermore, reduced the cellular content of 211 At in the EGF-stimulated cultures. DIDS had no effect on the forskolin-induced efflux of the two radionuclides. Conclusions: The magnitude of thyroidal 211 At uptake and efflux is similar to that of 125 I - , strongly dependent on the functional activity of the cells. However, 211 At efflux likely involves several permeating mechanisms with different sensitivity to DIDS, which are at least partly not shared by 125 I - . The results suggest that anion channel blockage is potentially useful to increase the absorbed dose from both 211 At and radioiodine in NIS-expressing tumours

  8. Organic Anion-Transporting Polypeptide (OATP)-Mediated Drug-Drug Interaction Study between Rosuvastatin and Cyclosporine A in Chimeric Mice with Humanized Liver.

    Science.gov (United States)

    Uchida, Masashi; Tajima, Yoriko; Kakuni, Masakazu; Kageyama, Yutaka; Okada, Taro; Sakurada, Eri; Tateno, Chise; Hayashi, Ryoji

    2018-01-01

    The influence of transporters on the pharmacokinetics of drugs is being increasingly recognized, and DDIs via transporters may be a risk factor for adverse events. Cyclosporine A, a strong OATP inhibitor, has been reported to increase the systemic exposure of rosuvastatin, an OATP substrate, by 7.1-fold in clinical studies. PXB mice are chimeric mice with humanized livers that are highly repopulated with human hepatocytes and have been widely used for drug discovery in drug metabolism and pharmacokinetics studies. In the present study, we examined in vivo and in vitro DDIs between rosuvastatin and cyclosporine A in PXB mice and fresh human hepatocytes (PXB cells) obtained from PXB mice. We initially investigated the active transport of rosuvastatin into PXB cells, and found concentration-dependent uptake with a Michaelis-Menten constant value of 4.0 μ mol/l and a V max value of 4.63 pmol/min per 10 6 cells. Cyclosporine A inhibited the uptake of rosuvastatin with an IC 50 value of 0.21 μ mol/l. We then examined in vivo DDIs, and the exposure of orally administered rosuvastatin increased by 3.3-fold and 11-fold in PXB mice pretreated with 10 and 50 mg/kg cyclosporine A, whereas it increased by 2.5-fold and 6.2-fold when rosuvastatin was administered intravenously, in studies that were conducted for considering gastrointestinal DDIs. The liver-to-blood concentration ratio of rosuvastatin was dose-dependently decreased by pretreatment with cyclosporine A in PXB mice and SCID mice. Observed DDIs in vivo were considered to be reasonable based on the estimated concentrations of cyclosporine A at the inlet to the liver and in the liver tissues of both mice. In conclusion, our results indicate that PXB mice might be a useful tool for predicting human OATP-mediated DDIs in drug discovery, and its limitation due to the differences of gastrointestinal condition from human should also be considered. Copyright © 2017 by The American Society for Pharmacology and Experimental

  9. Potentiometric anion selective sensors

    NARCIS (Netherlands)

    Antonisse, M.M.G.; Reinhoudt, David

    1999-01-01

    In comparison with selective receptors (and sensors) for cationic species, work on the selective complexation and detection of anions is of more recent date. There are three important components for a sensor, a transducer element, a membrane material that separates the transducer element and the

  10. Application of physiologically-based pharmacokinetic modeling to explore the role of kidney transporters in renal reabsorption of perfluorooctanoic acid in the rat

    International Nuclear Information System (INIS)

    Worley, Rachel Rogers; Fisher, Jeffrey

    2015-01-01

    ABSTRACT: Renal elimination and the resulting clearance of perfluorooctanoic acid (PFOA) from the serum exhibit pronounced sex differences in the adult rat. The literature suggests that this is largely due to hormonally regulated expression of organic anion transporters (OATs) on the apical and basolateral membranes of the proximal tubule cells that facilitate excretion and reabsorption of PFOA from the filtrate into the blood. Previously developed PBPK models of PFOA exposure in the rat have not been parameterized to specifically account for transporter-mediated renal elimination. We developed a PBPK model for PFOA in male and female rats to explore the role of Oat1, Oat3, and Oatp1a1 in sex-specific renal reabsorption and excretion of PFOA. Descriptions of the kinetic behavior of these transporters were extrapolated from in vitro studies and the model was used to simulate time-course serum, liver, and urine data for intravenous (IV) and oral exposures in both sexes. Model predicted concentrations of PFOA in the liver, serum, and urine showed good agreement with experimental data for both male and female rats indicating that in vitro derived physiological descriptions of transporter-mediated renal reabsorption can successfully predict sex-dependent excretion of PFOA in the rat. This study supports the hypothesis that sex-specific serum half-lives for PFOA are largely driven by expression of transporters in the kidney and contribute to the development of PBPK modeling as a tool for evaluating the role of transporters in renal clearance. - Highlights: • The PBPK model for PFOA in the rat explores the role of OATs in sex-specific clearance. • Descriptions of OAT kinetics were extrapolated from in vitro studies. • Model predictions showed good fit with experimental data for male and female rats.

  11. Sources, transport and reactivity of anionic and non-ionic surfactants in several aquatic ecosystems in SW Spain: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Lara-Martin, Pablo A. [Departamento de Quimica Fisica, Facultad de Ciencias del Mar y Ambientales, Universidad de Cadiz, Campus Rio San Pedro s/n, 11510 Puerto Real, Cadiz (Spain)], E-mail: pablo.lara@uca.es; Gomez-Parra, Abelardo; Gonzalez-Mazo, Eduardo [Departamento de Quimica Fisica, Facultad de Ciencias del Mar y Ambientales, Universidad de Cadiz, Campus Rio San Pedro s/n, 11510 Puerto Real, Cadiz (Spain)

    2008-11-15

    Presence, distribution and transport mechanisms of the four major synthetic surfactants -linear alkylbenzene sulfonates (LAS), alkyl ethoxysulfates (AES), nonylphenol ethoxylates (NPEOs) and alcohol ethoxylates (AEOs)- have been simultaneously studied in different aquatic ecosystems. Urban wastewater discharges and industrial activities were identified as the main sources for these compounds and their metabolites. LAS, AES and carboxylic metabolites remained in the dissolved form (87-99%). However, NPEOs and AEOs were mostly associated with particulate matter (65-86%), so their degradation in the water column was limited due to their lower bioavailability. It was also observed that sorption to the particulate phase was more intense for longer homologs/ethoxymers for all surfactants. With respect to surface sediments, AES levels were considerably below (<0.25 mg/kg) the values detected for LAS and NPEOs. Concentrations of AEOs, however, were occasionally higher (several tens of ppm) than those found for the rest of the target compounds in several sampling stations. - Occurrence and reactivity of the main synthetic surfactants in freshwater and marine systems are discussed.

  12. Hepatic uptake of conjugated bile acids is mediated by both sodium taurocholate cotransporting polypeptide and organic anion transporting polypeptides and modulated by intestinal sensing of plasma bile acid levels in mice.

    Science.gov (United States)

    Slijepcevic, Davor; Roscam Abbing, Reinout L P; Katafuchi, Takeshi; Blank, Antje; Donkers, Joanne M; van Hoppe, Stéphanie; de Waart, Dirk R; Tolenaars, Dagmar; van der Meer, Jonathan H M; Wildenberg, Manon; Beuers, Ulrich; Oude Elferink, Ronald P J; Schinkel, Alfred H; van de Graaf, Stan F J

    2017-11-01

    The Na + -taurocholate cotransporting polypeptide (NTCP/SLC10A1) is believed to be pivotal for hepatic uptake of conjugated bile acids. However, plasma bile acid levels are normal in a subset of NTCP knockout mice and in mice treated with myrcludex B, a specific NTCP inhibitor. Here, we elucidated which transport proteins mediate the hepatic uptake of conjugated bile acids and demonstrated intestinal sensing of elevated bile acid levels in plasma in mice. Mice or healthy volunteers were treated with myrcludex B. Hepatic bile acid uptake kinetics were determined in wild-type (WT), organic anion transporting polypeptide (OATP) knockout mice (lacking Slco1a/1b isoforms), and human OATP1B1-transgenic mice. Effects of fibroblast growth factor 19 (FGF19) on hepatic transporter mRNA levels were assessed in rat hepatoma cells and in mice by peptide injection or adeno-associated virus-mediated overexpression. NTCP inhibition using myrcludex B had only moderate effects on bile acid kinetics in WT mice, but completely inhibited active transport of conjugated bile acid species in OATP knockout mice. Cholesterol 7α-hydroxylase Cyp7a1 expression was strongly down-regulated upon prolonged inhibition of hepatic uptake of conjugated bile acids. Fgf15 (mouse counterpart of FGF19) expression was induced in hypercholanemic OATP and NTCP knockout mice, as well as in myrcludex B-treated cholestatic mice, whereas plasma FGF19 was not induced in humans treated with myrcludex B. Fgf15/FGF19 expression was induced in polarized human enterocyte-models and mouse organoids by basolateral incubation with a high concentration (1 mM) of conjugated bile acids. NTCP and OATPs contribute to hepatic uptake of conjugated bile acids in mice, whereas the predominant uptake in humans is NTCP mediated. Enterocytes sense highly elevated levels of (conjugated) bile acids in the systemic circulation to induce FGF15/19, which modulates hepatic bile acid synthesis and uptake. (Hepatology 2017;66:1631-1643).

  13. Expression and regulation of prostaglandin transporters, ATP-binding cassette, subfamily C, member 1 and 9, and solute carrier organic anion transporter family, member 2A1 and 5A1 in the uterine endometrium during the estrous cycle and pregnancy in pigs

    Directory of Open Access Journals (Sweden)

    Hwanhee Jang

    2017-05-01

    Full Text Available Objective Prostaglandins (PGs function in various reproductive processes, including luteolysis, maternal pregnancy recognition, conceptus development, and parturition. Our earlier study has shown that PG transporters ATP-binding cassette, subfamily C, member 4 (ABCC4 and solute carrier organic anion transporter family, member 2A1 (SLCO2A1 are expressed in the uterine endometrium in pigs. Since several other PG transporters such as ABCC1, ABCC9, SLCO4C1, and SLCO5A1 are known to be present in the uterine endometrium, this study investigated the expression of these PG transporters in the porcine uterine endometrium and placenta. Methods Uterine endometrial tissues were obtained from gilts on day (D 12 and D15 of the estrous cycle and days 12, 15, 30, 60, 90, and 114 of pregnancy. Results ABCC1, ABCC9, SLCO4C1, and SLCO5A1 mRNAs were expressed in the uterine endometrium, and levels of expression changed during the estrous cycle and pregnancy. Expression of ABCC1 and ABCC9 mRNAs was localized mainly to luminal and glandular epithelial cells in the uterine endometrium, and chorionic epithelial cells during pregnancy. Conceptuses during early pregnancy and chorioallantoic tissues from mid to late pregnancy also expressed these PG transporters. Estradiol-17β increased the expression of ABCC1 and SLCO5A1, but not ABCC9 and SLCO4C1 mRNAs and increasing doses of interleukin-1β induced the expression of ABCC9, SLCO4C1, and SLCO5A1 mRNAs in endometrial explant tissues. Conclusion These data showed that several PG transporters such as ABCC1, ABCC9, SLCO4C1, and SLCO5A1 were expressed at the maternal-conceptus interface, suggesting that these PG transporters may play an important role in the establishment and maintenance of pregnancy by regulating PG transport in the uterine endometrium and placenta in pigs.

  14. Ochratoxin A transport by the human breast cancer resistance protein (BCRP), multidrug resistance protein 2 (MRP2), and organic anion-transporting polypeptides 1A2, 1B1 and 2B1.

    Science.gov (United States)

    Qi, Xiaozhe; Wagenaar, Els; Xu, Wentao; Huang, Kunlun; Schinkel, Alfred H

    2017-08-15

    Ochratoxin A (OTA) is a fungal secondary metabolite that can contaminate various foods. OTA has several toxic effects like nephrotoxicity, hepatotoxicity, and neurotoxicity in different animal species, but its mechanisms of toxicity are still unclear. How OTA accumulates in kidney, liver, and brain is as yet unknown, but transmembrane transport proteins are likely involved. We studied transport of OTA in vitro, using polarized MDCKII cells transduced with cDNAs of the efflux transporters mouse (m)Bcrp, human (h)BCRP, mMrp2, or hMRP2, and HEK293 cells overexpressing cDNAs of the human uptake transporters OATP1A2, OATP1B1, OATP1B3, or OATP2B1 at pH7.4 and 6.4. MDCKII-mBcrp cells were more resistant to OTA toxicity than MDCKII parental and hBCRP-transduced cells. Transepithelial transport experiments showed some apically directed transport by MDCKII-mBcrp cells at pH7.4, whereas both mBcrp and hBCRP clearly transported OTA at pH6.4. There was modest transport of OTA by mMrp2 and hMRP2 only at pH6.4. OATP1A2 and OATP2B1 mediated uptake of OTA both at pH7.4 and 6.4, but OATP1B1 only at pH7.4. There was no detectable transport of OTA by OATP1B3. Our data indicate that human BCRP and MRP2 can mediate elimination of OTA from cells, thus reducing OTA toxicity. On the other hand, human OATP1A2, OATP1B1, and OATP2B1 can mediate cellular uptake of OTA, which could aggravate OTA toxicity. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Secretion of organic anions by hepatocytes : Involvement of homologues of the multidrug resistance protein

    NARCIS (Netherlands)

    Muller, M; Roelofsen, H; Jansen, PLM

    The canalicular multispecific organic anion transporter (cMOAT) is one of at least four ATP-dependent transport systems identified so far in the canalicular membrane domain. Using mutant rat strains that lack organic anion secretion, the substrate specificity of cMOAT has been characterized. cMOAT

  16. Entecavir Interacts with Influx Transporters hOAT1, hCNT2, hCNT3, but Not with hOCT2: The Potential for Renal Transporter-Mediated Cytotoxicity and Drug-Drug Interactions

    Czech Academy of Sciences Publication Activity Database

    Mandíková, J.; Volková, M.; Pávek, P.; Navrátilová, L.; Hyršová, L.; Janeba, Zlatko; Pavlík, J.; Bárta, P.; Trejtnar, F.

    2016-01-01

    Roč. 6, Jan 5 (2016), č. článku 304. ISSN 1663-9812 Institutional support: RVO:61388963 Keywords : antivirals * nephrotoxicity * renal disposition * drug-drug interactions Subject RIV: CC - Organic Chemistry Impact factor: 4.400, year: 2016 http://journal.frontiersin.org/article/10.3389/fphar.2015.00304/full

  17. The many ways of making anionic clays

    Indian Academy of Sciences (India)

    Unknown

    trivalent metal hydroxides and their hydroxy salts are actually anionic clays consisting of positively charged hydroxide layers with anions intercalated in the interlayer region. The anionic clays exhibit anion sorption, anion diffusion and exchange properties together with surface basicity making them materials of importance ...

  18. The many ways of making anionic clays

    Indian Academy of Sciences (India)

    Together with hydrotalcite-like layered double hydroxides, bivalent and trivalent metal hydroxides and their hydroxy salts are actually anionic clays consisting of positively charged hydroxide layers with anions intercalated in the interlayer region. The anionic clays exhibit anion sorption, anion diffusion and exchange ...

  19. [Exploring the Correlation between Pi and Shen from the Excretion of AA-I and Expressions of Or- ganic Anion Transporting Polypeptide 2al and 2 b1 in Pi Deficiency Model Rats].

    Science.gov (United States)

    Xiang, Ting; Ren, Bin; Yang, Zhang-bin; Sun, Bao-guo; Chen, Ze-xiong; Chen, Yan; Zhang, Shi-jun

    2015-10-01

    To explore the correlation between Pi and Shen by observing the relationship between the metabolism of aristolochic acid (AA) and mRNA and protein expression levels of organic anion transporting polypeptide (oatp) superfamily member 2a1 and 2 b1 (oatp2al and oatp2bl) in renal, small intestinal, and large intestinal tissues of Pi deficiency syndrome (PDS) model rats. Totally 46 Sprague-Dawley (SD) rats were randomly divided into four groups, i.e., the blank group (n = 12), the PDS group (n = 22), the AA-I group (n = 6), and the PDS AA-I group (n = 6). PDS model was established by subcutaneously injecting Reserpine at the daily dose of 5 mg/kg for 16 successive days. Carotid intubation was performed in 6 rats selected from the blank group and the PDS group. Pharmacokinetics of AA-I were detected at 5, 15, 30, 45, and 60 min after gastrogavage of AA-I. AA-I concentrations in renal, small intestinal, and large intestinal tissues of 10 rats selected from the PDS group were determined. Normal saline was administered to 6 rats selected from the PDS group and the blank group by gastrogavage. Renal, small intestinal, and large intestinal tissues were collected in the AA-I group and the PDS AA-I group at 60 min after gastrogavage of AA-I. mRNA and protein expression levels of oatp2a1 and oatp2b1 in each tissue were detected using real-time polymerase chain reaction (RT- PCR) and Western blot. Compared with the blank group, plasma concentrations of in vivo AA-I were obviously higher in the PDS group at 15, 30, 45, and 60 min after gastrogavage of AA-I with statistical difference (P AA-I were obviously decreased at 60 min after gastrogavage of AA-I; AA-I concentrations in renal and large intestinal tissues were elevated; AA-I concentrations in small intestinal tissues were obviously reduced in the PDS group. There was no statistical difference in mRNA expression levels of oatp2a1 and oatp2b1 in the aforesaid three tissues of rats between the blank group and the PDS group

  20. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng

    2014-01-01

    In the recent surge of metal-free polymerization techniques, phosphazene bases have shown their remarkable potential as organic promoters/catalysts for the anionic polymerization of various types of monomers. By complexation with the counterion (e.g. proton or lithium cation), phosphazene base significantly improve the nucleophilicity of the initiator/chain-end resulting in rapid and usually controlled anionic/quasi-anionic polymerization. In this review, we will introduce the general mechanism, i.e. in situ activation (of initiating sites) and polymerization, and summarize the applications of such a mechanism on macromolecular engineering toward functionalized polymers, block copolymers and complex macromolecular architectures.

  1. Pentaarylfullerenes as noncoordinating cyclopentadienyl anions

    NARCIS (Netherlands)

    Bouwkamp, Marco W.; Meetsma, Auke

    2009-01-01

    The first example of an early-transition-metal complex involving a pentaarylfullerene was prepared. Instead of half-sandwich complexes, solvent separated ion pairs were obtained in which the pentaarylfullerene moiety acts as noncoordinating cyclopentadienyl anion.

  2. Transportation

    International Nuclear Information System (INIS)

    Anon.

    1998-01-01

    Here is the decree of the thirtieth of July 1998 relative to road transportation, to trade and brokerage of wastes. It requires to firms which carry out a road transportation as well as to traders and to brokers of wastes to declare their operations to the prefect. The declaration has to be renewed every five years. (O.M.)

  3. Modeling Donnan Dialysis Separation for Carboxylic Anion Recovery

    DEFF Research Database (Denmark)

    Prado Rubio, Oscar Andres; Møllerhøj, Martin; Jørgensen, Sten Bay

    2010-01-01

    dynamic model for transport of multiple ions through an anion exchange membrane is derived based on an irreversible thermodynamics approach. This model accounts for the convective transport of the dissociated and undissociated species in the channels with diffusion and migration across the boundary...... layers and membranes. Donnan equilibrium, flux continuity of the transported ions, the electroneutrality condition and Faraday's law are employed to describe the electrical potential and concentration discontinuities at the interfaces. The Nernst-Planck equation is used to model the ion transport though...

  4. Bound anionic states of adenine

    Energy Technology Data Exchange (ETDEWEB)

    Haranczyk, Maciej; Gutowski, Maciej S; Li, Xiang; Bowen, Kit H

    2007-03-20

    Anionic states of nucleic acid bases are involved in DNA damage by low-energy electrons and in charge transfer through DNA. Previous gas phase studies of free, unsolvated nucleic acid base parent anions probed only dipole-bound states, which are not present in condensed phase environments, but did not observe valence anionic states, which for purine bases, are thought to be adiabatically unbound. Contrary to this expectation, we have demonstrated that some thus far ignored tautomers of adenine, which result from enamine-imine transformations, support valence anionic states with electron vertical detachment energies as large as 2.2 eV, and at least one of these anionic tautomers is adiabatically bound. Moreover, we predict that the new anionic tautomers should also dominate in solutions and should be characterized by larger values of electron vertical detachment energy than the canonical valence anion. All of the new-found anionic tautomers might be formed in the course of dissociative electron attachment followed by a hydrogen atom attachment to a carbon atom, and they might affect the structure and properties of DNA and RNA exposed to low-energy electrons. The discovery of these valence anionic states of adenine was facilitated by the development of: (i) a new experimental method for preparing parent anions of nucleic acid bases for photoelectron experiments, and (ii) a new combinatorial/ quantum chemical approach for identification of the most stable tautomers of organic molecules. The computational portion of this work was supported by the: (i) Polish State Committee for Scientific Research (KBN) Grants: DS/8000-4-0140-7 (M.G.) and N204 127 31/2963 (M.H.), (ii) European Social Funds (EFS) ZPORR/2.22/II/2.6/ARP/U/2/05 (M.H.), and (iii) US DOE Office of Biological and Environmental Research, Low Dose Radiation Research Program (M.G.). M.H. holds the Foundation for Polish Science (FNP) award for young scientists. The calculations were performed at the Academic

  5. Transportation

    National Research Council Canada - National Science Library

    Allshouse, Michael; Armstrong, Frederick Henry; Burns, Stephen; Courts, Michael; Denn, Douglas; Fortunato, Paul; Gettings, Daniel; Hansen, David; Hoffman, Douglas; Jones, Robert

    2007-01-01

    .... The ability of the global transportation industry to rapidly move passengers and products from one corner of the globe to another continues to amaze even those wise to the dynamics of such operations...

  6. Pollen Tube Growth Regulation by Free Anions Depends on the Interaction between the Anion Channel SLAH3 and Calcium-Dependent Protein Kinases CPK2 and CPK20.

    NARCIS (Netherlands)

    Gutermuth, T.; Lassig, R.; Portes, M.T.; Maierhofer, T.; Romeis, T.; Borst, J.W.; Hedrich, R.; Feijó, J.A.; Konrad, K.R.

    2013-01-01

    Apical growth in pollen tubes (PTs) is associated with the presence of tip-focused ion gradients and fluxes, implying polar localization or regulation of the underlying transporters. The molecular identity and regulation of anion transporters in PTs is unknown. Here we report a negative gradient of

  7. Calcium-tolerant anionic surfactants

    NARCIS (Netherlands)

    Kooreman, Alexander

    1995-01-01

    One of the problems of applying anionic surfactants in, for example, laundry detergents is the precipitation of calcium salts. Much effort has been directed towards avoiding precipitation. There are at least three ways for tackling the problem. The first involves the use of a large quantity of

  8. Quantum mechanics of toroidal anions

    International Nuclear Information System (INIS)

    Afanas'ev, G.N.

    1990-01-01

    We consider a toroidal solenoid with an electric charge attached to it. It turns out that statistical properties of the wave function describing interacting toroidal anions depend on both their relative position and orientation. The influence of the particular gauge choice on the exchange properties of the wave function is studied. 30 refs.; 6 figs

  9. Methods and systems for measuring anions

    KAUST Repository

    Masih, Dilshad

    2016-08-18

    Embodiments of the present disclosure provide for methods for detecting the presence and/or concentration of anions in a solution, systems for detecting the presence and/or concentration of anions in a solution, anion sensor systems, and the like.

  10. The anion-binding polyanion: a molecular cobalt vanadium oxide with anion-sensitive visual response.

    Science.gov (United States)

    Seliverstov, Andrey; Forster, Johannes; Heiland, Magdalena; Unfried, Johannes; Streb, Carsten

    2014-07-25

    An anionic molecular cobalt vanadium oxide cluster, (n-Bu4N)3[Co(AcO)V4O12] and its use as anion binding site is reported. Cluster formation is controlled by an anion-dependent dynamic solution equilibrium. Reversible anion binding in solution leads to significant spectral changes, allowing the ratiometric optical detection of the anion concentration in situ, even under harsh thermal conditions (T = 90 °C). Comparative studies showed that the spectral response is dependent on the type of anion so that carboxylates, weakly coordinating anions and halides can be distinguished.

  11. Laser cooling of molecular anions.

    Science.gov (United States)

    Yzombard, Pauline; Hamamda, Mehdi; Gerber, Sebastian; Doser, Michael; Comparat, Daniel

    2015-05-29

    We propose a scheme for laser cooling of negatively charged molecules. We briefly summarize the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C_{2}^{-}, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photodetachment process is present, as well as Doppler laser cooling of trapped C_{2}^{-}, are also simulated. This cooling scheme has an impact on the study of cold molecules, molecular anions, charged particle sources, and antimatter physics.

  12. Laser Cooling of Molecular Anions

    CERN Document Server

    Yzombard, Pauline; Gerber, Sebastian; Doser, Michael; Comparat, Daniel

    2015-01-01

    We propose a scheme for laser cooling of negatively charged molecules. We briefly summarise the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C$\\_2^-$, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photo-detachment process is present, as well as Doppler laser cooling of trapped C$\\_2^-$, are also simulated. This cooling scheme has an impact on the study of cold molecules, molecular anions, charged particle sources and antimatter physics.

  13. Transport of 3-fluoro-l-α-methyl-tyrosine (FAMT by organic ion transporters explains renal background in [18F]FAMT positron emission tomography

    Directory of Open Access Journals (Sweden)

    Ling Wei

    2016-02-01

    Full Text Available A PET tracer for tumor imaging, 3-18F-l-α-methyl-tyrosine ([18F]FAMT, has advantages of high cancer-specificity and low physiological background. In clinical studies, FAMT-PET has been proved useful for the detection of malignant tumors and their differentiation from inflammation and benign lesions. The tumor specific uptake of FAMT is due to its high-selectivity to cancer-type amino acid transporter LAT1 among amino acid transporters. In [18F]FAMT PET, kidney is the only organ that shows high physiological background. To reveal transporters involved in renal accumulation of FAMT, we have examined [14C]FAMT uptake on the organic ion transporters responsible for the uptake into tubular epithelial cells. We have found that OAT1, OAT10 and OCTN2 transport [14C]FAMT. The [14C]FAMT uptake was inhibited by probenecid, furosemide and ethacrynic acid, consistent with the properties of the transporters. The amino acid uptake inhibitor, 2-amino-2-norbornanecarboxylic acid (BCH, also inhibited the [14C]FAMT uptake, whereas OCTN2-mediated [14C]FAMT uptake was Na+-dependent. We propose that FAMT uptake by OAT1, OAT10 and OCTN2 into tubular epithelial cells could contribute to the renal accumulation of FAMT. The results from this study would provide clues to the treatments to reduce renal background and enhance tumor uptake as well as to designing PET tracers with less renal accumulation.

  14. Anion

    Directory of Open Access Journals (Sweden)

    A. Vadivel Murugan

    2003-01-01

    . Its characterization is investigated by Fourier Transform Infrared Spectroscopy (FT-IR and Scanning Electron Microscopy (SEM. The hybrid material presents predominantly high electronic conductivities of around 2.0 and 7.0 S cm-1 at 300 and 400K respectively.

  15. Decreased anion gap in polyclonal hypergammaglobulinemia.

    Science.gov (United States)

    Qujeq, Durdi; Mohiti, Javad

    2002-02-01

    The anion gap has proved a valuable tool in the diagnosis of various forms of acid-base disorders, although the importance of slight rises in the anion gap remains unclear. The concept of the anion gap is often misunderstood and misapplied. The relationship between gammaglobulins and the serum anion gap has not received much attention except for reports of a narrowing of the gap associated with certain monoclonal immunoglobulin G gammopathies. We present patients with polyclonal gammopathy, the magnitude of which correlated strongly and negatively with the anion gap. The anion gap can be readily calculated from routine laboratory data, and anion gap was calculated as ([Na] +[K])- ([Cl] + [HCO3]). Serum anion gaps were determined in 206 patients with polyclonal hypergammaglobulinemia and 63 healthy subjects. Serum sodium and potassium ions concentration were determined by flame photometry. Serum bicarbonate level was measured as total carbon dioxide content. Serum chloride level was determined by chlorimetric titration with silver ions. All patients with polyclonal hypergammaglobulinemia had a statistically significant reduction in their mean serum anion gaps (6.4 +/- 1.2 mmol/L) when compared with normal control volunteers (15.3 +/- 2.4 mmol/L), p anion gap and gammaglobulins concentration.

  16. Drug transport proteins in the liver

    NARCIS (Netherlands)

    Faber, Klaas Nico; Muller, M.; Jansen, P.LM

    2003-01-01

    Together with drug metabolising enzymes, transmembrane transporters are important determinants of drug metabolism and drug clearance by the liver. Hepatic uptake of organic anions, cations, prostaglandins and bile salts is supported by dedicated transporter proteins in the basolateral (sinusoidal)

  17. Environmental behavior of inorganic anions

    International Nuclear Information System (INIS)

    Garland, T.R.; Cataldo, D.A.; Fellows, R.J.; Wildung, R.E.

    1987-01-01

    Recent efforts have addressed two aspects of anion behavior in the soil/plant system. The first involves evaluation of the gaseous component of the terrestrial iodine cycle in soils and plants. Field analyses of 129 I in soils and vegetation adjacent to a fuels reprocessing facility, which was idle for 10 years prior to the study, indicated that there may be a significant gaseous component to the terrestrial iodine cycle. Soil substrates, including a silt-sand, organic forest soil, quartz sand, and a sterilized soil, were amended with radioiodide, and the rates and quality of the volatile components evaluated

  18. Interstellar Anions: The Role of Quantum Chemistry.

    Science.gov (United States)

    Fortenberry, Ryan C

    2015-10-01

    Six anions have been conclusively detected in the interstellar medium (ISM). They all arrived within a five-year window ending five years ago. Why have no new anions been detected? It is likely a lack of laboratory data for novel anions. This work reviews the role that valence and dipole-bound excited states may play in the formation, detection, and lifetime of anions that may yet be observed in the ISM and how quantum chemistry enhances this understanding. The list of interstellar anions has certainly not been exhausted by any means, but electronic, spectroscopic, and structural data must be provided to aid in any future detections. Quantum chemistry has the flexibility and completeness to provide a full picture of these systems and has shown exceptional accuracies of late. The work reviewed herein gives an overview of what quantum chemical computations have produced and will continue to provide related to anions and how this will enhance both laboratory experiment and astronomical observation.

  19. Clinical usefulness of the serum anion gap.

    Science.gov (United States)

    Lee, Sik; Kang, Kyung Pyo; Kang, Sung Kyew

    2006-03-01

    The anion gap in the serum is useful in the interpretation of acid-base disorders and in the diagnosis of other conditions. In the early 1980s, ion-selective electrodes for specific ionic species were introduced for the measurement of serum electrolytes. This new method has caused a shift of the anion gap from 12±4 mEq/L down 6±3 mEq/L. It is worthy for clinicians to understand the range of normal anion gap and the measuring methods for serum sodium and chloride in the laboratories that support their practice. While an increase in the anion gap is almost always caused by retained unmeasured anions, a decrease in the anion gap can be generated by multiple mechanisms.

  20. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization-high vacuum techniques (HVTs) are doubtlessly the most prominent and reliable experimental tools to prepare polymer samples with well-defined and, in many cases, complex macromolecular architectures. Due to the high demands for time and skilled technical personnel, HVTs are currently used in only a few research laboratories worldwide. Instead, most researchers in this filed are attracted to more facile Schlenk techniques. The basic principle of this technique followed in all laboratories is substantially the same, i.e. the use of alternate vacuum and inert gas atmosphere in glass apparatus for the purification/charging of monomer, solvents, additives, and for the manipulation of air-sensitive compounds such as alkyl metal initiators, organometallic or organic catalysts. However, it is executed quite differently in each research group in terms of the structure of Schlenk apparatus (manifolds, connections, purification/storage flasks, reactors, etc.), the use of small supplementary devices (soft tubing, cannulas, stopcocks, etc.) and experimental procedures. The operational methods are partly purpose-oriented while also featured by a high flexibility, which makes it impossible to describe in detail each specific one. In this chapter we will briefly exemplify the application of Schlenk techniques for anionic polymerization by describing the performance of a few experiments from our own work.

  1. Effect of chemical retention on anionic species diffusion in compacted clays

    International Nuclear Information System (INIS)

    Bazer-Bachi, Frederic

    2005-01-01

    Anionic radioisotopes are of particular importance within the framework of the calculated health risk associated with high-level and long-lived intermediate-level underground radioactive waste disposal. Therefore, the objective of this work is the construction of a transport model coupled with chemistry in order to quantify the behaviour of anionic solutes in the Callovo-Oxfordian (CO x ) argillite, the argillaceous host rock of the ANDRA Meuse/Haute-Marne underground laboratory. An experimental methodology was defined to characterize this migration, several experimental methods being implemented: batch experiments, laboratory columns and through-diffusion cells. The study of the diffusion of the non-sorbing anionic tracer 36 Cl - highlighted the fact that, due to anionic exclusion, anions only had access to a part of the porosity. The retention of 35 SO 4 2- and 125 I- on CO x argillite was then characterized, quantified by batch experiments and confirmed by other experimental methods. Nevertheless, their migration was less retarded than expected by a model based on batch experiments and on 36 Cl - diffusive data. This difference was explained by anion exclusion which reduced sorption site accessibility. Thus, the intensity of this phenomenon has to be considered to model anion migration in compacted clays. (author) [fr

  2. Electrolyte secretion by the isolated cat pancreas during replacement of extracellular bicarbonate by organic anions and chloride by inorganic anions.

    Science.gov (United States)

    Case, R M; Hotz, J; Hutson, D; Scratcherd, T; Wynne, R D

    1979-01-01

    acetate. 7. These observations illustrate that an extracellular source of permeant anions is required for optimal pancreatic bicarbonate secretion to occur. This may indicate the participation of an anion exchange carrier in the transport events responsible for this secretory process.

  3. Ionic Block Copolymers for Anion Exchange Membranes

    Science.gov (United States)

    Tsai, Tsung-Han; Herbst, Dan; Giffin, Guinevere A.; di Noto, Vito; Witten, Tom; Coughlin, E. Bryan

    2013-03-01

    Anion exchange membrane (AEM) fuel cells have regained interest because it allows the use of non-noble metal catalysts. Until now, most of the studies on AEM were based on random polyelectrolytes. In this work, Poly(vinylbenzyltrimethylammonium bromide)-b- (methylbutylene) ([PVBTMA][Br]-b-PMB) was studied by SAXS, TEM and dielectric spectroscopy to understand the fundamental structure-conductivity relationship of ion transport mechanisms within well-ordered block copolymers. The ionic conductivity and the formation of order structure were dependent on the casting solvent. Higher ion exchange capacity (IEC) of the membranes showed higher conductivity at as IEC values below 1.8mmol/g, as above this, the ionic conductivity decreases due to more water uptake leading to dilution of charge density. The humidity dependence of morphology exhibited the shifting of d-spacing to higher value and the alteration in higher characteristic peak of SAXS plot as the humidity increase from the dry to wet state. This phenomenon can be further explained by a newly developed polymer brush theory. Three ionic conduction pathways with different conduction mechanism within the membranes can be confirmed by broadband electric spectroscopy. US Army MURI (W911NF1010520)

  4. ANIONS FUNCTIONS IN TRANSITION METALS COORDINATION COMPOUNDS

    Directory of Open Access Journals (Sweden)

    T. V. Koksharova

    2016-04-01

    Full Text Available The effect of anions on the structure and properties of coordination compounds of transition metals has been discussed. The examples of changes in the composition of the formed complexes by replacement of the anion are given: metal ratio to a neutral ligand, the composition of the inner sphere, the direction of template synthesis. Anions can determine the presence of isomers in complexes with different ligands. Examples of conformational, ionization isomerism, inner sphere bond isomerization are given. The nature of the coordination polyhedron is highly sensitive to the replacement of the anion too. Examples of coordination compounds where the anion change causes a change in coordination capacity of neutral ligands and the strength of their bonds with the metal, coordination number and geometry of the inner sphere, the organization of molecular structures (the structure of the hydrogen bond networks and the degree of polymerization, crystal packing. The anions significantly affect the binding of the solvent molecules, complexes magnetic and luminescent properties, they can change the compound color, the mechanisms of thermolysis. Anions make a very noticeable influence on possible redox processes following the complexation in some cases. Anions in the coordination sphere can change catalytic and biochemical processes as well as the ways of interaction of metal ions with drugs.

  5. The many ways of making anionic clays

    Indian Academy of Sciences (India)

    Unknown

    Indian Academy of Sciences. 671. The many ways of making anionic ... In all these cases, the negative charge is compensated for by the inclusion of positive ions in the interlayer region, by virtue ..... as anionic clays. Acknowledgements. The authors thank the Department of Science and Technology, New Delhi for financial.

  6. Test procedure for anion exchange chromatography

    International Nuclear Information System (INIS)

    Cooper, T.D.

    1994-01-01

    Plutonium from stored nitrate solutions will be sorbed onto anion exchange resins and converted to storable plutonium dioxide. Useful information will be simultaneously gained on the thermal stability and ion exchange capacity of four commercially available anion exchange resins over several years and under severe degradative conditions. This information will prove useful in predicting the safe and efficient lifetimes of these resins

  7. Hydrogen in anion vacancies of semiconductors

    Science.gov (United States)

    Du, Mao-Hua; Singh, David

    2009-03-01

    Hydrogen typically terminates the dangling bonds around vacancies in semiconductors, thereby, partially or completely passivating the vacancies. However, it has been shown recently that hydrogen in anion vacancies of many semiconductors, such as ZnO, MgO, InN, SnO2, and GaN, takes multi-coordinated structures and acts as shallow donors, providing n-type conductivity to the materials. We study the hydrogen in the anion vacancies of a series of II-VI and III-V semiconductors using density functional calculations. The results on these materials show that, in the anion vacancies of polar II-VI semiconductors, the hydrogen is usually anionic and is coordinated with more than one cation atoms as a result of the relatively high ionicity of the host materials. The hydrogen coordination number depends on the host anion size. On the other hand, in more covalent semiconductors such as some III-V semiconductors, the single cation-H bonding configuration may become most stable. In the anion vacancies of ZnX and CdX where X represents anions, hydrogen is typically amphoteric except for oxides, in which the small anion size prohibits the formation of the cation-cation bond that is required for the acceptor configuration.

  8. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

    Skaarup, Steen; Bay, Lasse; Vidanapathirana, K.

    2003-01-01

    Polypyrrole (PPy) polymer films permanently doped with large, immobile anion dodecyl benzene sulfonate (DBS) have been characterized by cyclic voltammetry in order to clarify the roles of cations and anions in the aqueous electrolyte as mobile ions in the film. Aqueous solutions of 0.05-0.1 M...

  9. Fungal growth on anion surfactant medium.

    Science.gov (United States)

    Hamada, Nobuo; Abe, Niichiro

    2009-12-01

    Before the present study, no fungi using anion surfactant as a nutrient had been identified, although some fungi were known to use nonion surfactant. Washing water collected from 63 washing machines was inoculated onto 0.1% LAS (Sodium dodecyl benzenesulfonate) anion surfactant media to identify fungi that can feed on anion-surfactant. Small dark colonies of fungi were found on several of the Petri-dishes from 12 days after inoculation. These were identified as Cladophialophora boppii and Exophiala spinifera using morphological features and rDNA data. A number of the isolates of C. boppii specifically were recognized as using anion surfactant as a nutrient. The growth characteristics of the two fungal species were examined on surfactant media of three kinds. Apart from anion surfactant, the fungi were also able to grow on nonion surfactant and on soap. The application of these fungi for environmental cleansing after detergent pollution is also discussed.

  10. Creating molecular macrocycles for anion recognition

    Directory of Open Access Journals (Sweden)

    Amar H. Flood

    2016-03-01

    Full Text Available The creation and functionality of new classes of macrocycles that are shape persistent and can bind anions is described. The genesis of triazolophane macrocycles emerges out of activity surrounding 1,2,3-triazoles made using click chemistry; and the same triazoles are responsible for anion capture. Mistakes made and lessons learnt in anion recognition provide deeper understanding that, together with theory, now provides for computer-aided receptor design. The lessons are acted upon in the creation of two new macrocycles. First, cyanostars are larger and like to capture large anions. Second is tricarb, which also favors large anions but shows a propensity to self-assemble in an orderly and stable manner, laying a foundation for future designs of hierarchical nanostructures.

  11. Closing the gap on unmeasured anions

    Science.gov (United States)

    Kellum, John A

    2003-01-01

    Many critically ill and injured patients, especially those with metabolic acidosis, have abnormally high levels of unmeasured anions in their blood. At the same time, such patients are prone to hypoalbuminemia, which makes the traditional anion gap calculation inaccurate. Thus, little is known about the epidemiology and clinical consequences of an excess in unmeasured anions in the blood. Indeed, even the etiology of these "missing ions" is often unclear. Unfortunately, more precise means of quantifying unmeasured anions, such as the strong ion gap (SIG), are cumbersome to use clinically. However, a simple means of correcting the anion gap can be used to estimate SIG and may provide additional insight into this common clinical problem. PMID:12793870

  12. Anion Gap Blood Test: MedlinePlus Lab Test Information

    Science.gov (United States)

    ... https://medlineplus.gov/labtests/aniongapbloodtest.html Anion Gap Blood Test To use the sharing features on this page, please enable JavaScript. What is an Anion Gap Blood Test? An anion gap blood test is a way ...

  13. Alkaline Anion-Exchange Membranes Containing Mobile Ion Shuttles.

    Science.gov (United States)

    Ge, Xiaolin; He, Yubin; Guiver, Michael D; Wu, Liang; Ran, Jin; Yang, Zhengjin; Xu, Tongwen

    2016-05-01

    A new class of alkaline anion-exchange membranes containing mobile ion shuttles is developed. It is achieved by threading ionic linear guests into poly(crown ether) hosts via host-guest molecular interaction. The thermal- and pH-triggered shuttling of ionic linear guests remarkably increases the solvation-shell fluctuations in inactive hydrated hydroxide ion complexes (OH(-) (H2 O)4 ) and accelerates the OH(-) transport. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Clinical Usefulness of the Serum Anion Gap

    OpenAIRE

    Lee, Sik; Kang, Kyung Pyo; Kang, Sung Kyew

    2006-01-01

    The anion gap in the serum is useful in the interpretation of acid-base disorders and in the diagnosis of other conditions. In the early 1980s, ion-selective electrodes for specific ionic species were introduced for the measurement of serum electrolytes. This new method has caused a shift of the anion gap from 12±4 mEq/L down 6±3 mEq/L. It is worthy for clinicians to understand the range of normal anion gap and the measuring methods for serum sodium and chloride in the laboratories that suppo...

  15. MODERN TECHNOLOGY OF ANIONIC POLYMERIZATION MONOMERS

    Directory of Open Access Journals (Sweden)

    A. V. Tkachev

    2013-01-01

    Full Text Available The preconditions of use in the manufacture of automobile tyres of vulcanizates-based mortar butadienestyrene rubber with a high content of 1.2 links butadiene and statistical distribution of styrene are formulated. Set out scientific researches in the field of anionic co-polymerization of diene and vinyl aromatic monomers. Formulation of catalytic systems applied in processes of anionic copolymerization of monomers are given. The reasons of formation of gel in the process of anionic polymerization of monomers and terms of their elimination are considered.

  16. Experimental evidence for the functional relevance of anion-π interactions

    Science.gov (United States)

    Dawson, Ryan E.; Hennig, Andreas; Weimann, Dominik P.; Emery, Daniel; Ravikumar, Velayutham; Montenegro, Javier; Takeuchi, Toshihide; Gabutti, Sandro; Mayor, Marcel; Mareda, Jiri; Schalley, Christoph A.; Matile, Stefan

    2010-07-01

    Attractive in theory and confirmed to exist, anion-π interactions have never really been seen at work. To catch them in action, we prepared a collection of monomeric, cyclic and rod-shaped naphthalenediimide transporters. Their ability to exert anion-π interactions was demonstrated by electrospray tandem mass spectrometry in combination with theoretical calculations. To relate this structural evidence to transport activity in bilayer membranes, affinity and selectivity sequences were recorded. π-acidification and active-site decrowding increased binding, transport and chloride > bromide > iodide selectivity, and supramolecular organization inverted acetate > nitrate to nitrate > acetate selectivity. We conclude that anion-π interactions on monomeric surfaces are ideal for chloride recognition, whereas their supramolecular enhancement by π,π-interactions appears perfect to target nitrate. Chloride transporters are relevant to treat channelopathies, and nitrate sensors to monitor cellular signaling and cardiovascular diseases. A big impact on organocatalysis can be expected from the stabilization of anionic transition states on chiral π-acidic surfaces.

  17. Sulfate transport in toad skin

    DEFF Research Database (Denmark)

    Larsen, Erik Hviid; Simonsen, K

    1988-01-01

    1. In short-circuited toad skin preparations exposed bilaterally to NaCl-Ringer's containing 1 mM SO2(-4), influx of sulfate was larger than efflux showing that the skin is capable of transporting sulfate actively in an inward direction. 2. This active transport was not abolished by substituting ...... (sulfate:bicarbonate exchange) and self-exchange diffusion take place. Irrespective of the mechanism of transport, sulfate is probably transported as a monovalent anion species....

  18. Two independent anion transport systems in rabbit mandibular salivary glands

    DEFF Research Database (Denmark)

    Novak, I; Young, J A

    1986-01-01

    in the following sequence: Br = greater than Cl greater than I = greater than NO3 greater than isethionate. Furosemide, 1.0 and 0.1 mmol/l, inhibited Cl-supported secretion by 97-99% and 70-78%, respectively. SITS, 0.1 mmol/l, had no effect and amiloride, 1.0 mmol/l, caused a 55-65% inhibition. Addition of SITS...... to amiloride-treated glands produced no further effect. In glands perfused with Cl-free solutions, but containing 25 mM HCO3, amiloride, 1.0 mmol/l, inhibited secretion by 95% and methazolamide, 0.1 mmol/l, by 55%. In glands perfused with solutions containing both HCO3 and Cl, furosemide had smaller effects...... stimulated secretion by about 30%, but when infused in addition to furosemide (0.1 mmol/l), it inhibited by about 20%. Amiloride (1.0 mmol/l) caused no inhibition. The results suggest that there are at least three distinct carriers in the rabbit mandibular gland. One is a furosemide-sensitive Na-coupled Cl...

  19. Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance

    International Nuclear Information System (INIS)

    Bowman-James, K.; Wilson, G.; Moyer, B. A.

    2004-01-01

    This project involves the design and synthesis of receptors for oxoanions of environmental importance, including emphasis on high level and low activity waste. Target anions have included primarily oxoanions and a study of the basic concepts behind selective binding of target anions. A primary target has been sulfate because of its deleterious influence on the vitrification of tank wastes

  20. Correction of the anion gap for albumin in order to detect occult tissue anions in shock.

    Science.gov (United States)

    Hatherill, M; Waggie, Z; Purves, L; Reynolds, L; Argent, A

    2002-12-01

    It is believed that hypoalbuminaemia confounds interpretation of the anion gap (AG) unless corrected for serum albumin in critically ill children with shock. To compare the ability of the AG and the albumin corrected anion gap (CAG) to detect the presence of occult tissue anions. Prospective observational study in children with shock in a 22 bed multidisciplinary paediatric intensive care unit of a university childrenrsquo;s hospital. Blood was sampled at admission and at 24 hours, for acid-base parameters, serum albumin, and electrolytes. Occult tissue anions (lactate + truly "unmeasured" anions) were calculated from the strong ion gap. The anion gap ((Na + K) - (Cl + bicarbonate)) was corrected for serum albumin using the equation of Figge: AG + (0.25 x (44 - albumin)). Occult tissue anions (TA) predicted by the anion gap were calculated by (anion gap - 15 mEq/l). Optimal cut off values of anion gap were compared by means of receiver operating characteristic (ROC) curves. Ninety three sets of data from 55 children (median age 7 months, median weight 4.9 kg) were analysed. Data are expressed as mean (SD), and mean bias (limits of agreement). The incidence of hypoalbuminaemia was 76% (n = 42/55). Mean serum albumin was 25 g/l (SD 8). Mean AG was 15.0 mEq/l (SD 6.1), compared to the CAG of 19.9 mEq/l (SD 6.6). Mean TA was 10.2 mmol/l (SD 6.3). The AG underestimated TA with mean bias 10.2 mmol/l (4.1-16.1), compared to the CAG, mean bias 5.3 mmol/l (0.4-10.2). A clinically significant increase of TA >5 mmol/l was present in 83% (n = 77/93) of samples, of which the AG detected 48% (n = 36/77), and the CAG 87% (n = 67/77). Post hoc ROC analysis revealed optimal cut off values for detection of TA >5 mmol/l to be AG >10 mEq/l, and CAG >15.5 mEq/l. Hypoalbuminaemia is common in critically ill children with shock, and is associated with a low observed anion gap that may fail to detect clinically significant amounts of lactate and other occult tissue anions. We suggest that

  1. Absence of transepithelial anion exchange by rabbit OMCD: Evidence against reversal of cell polarity

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Matsuhiko; Schuster, V.L.; Stokes, J.B. (Univ. of Iowa College of Medicine, Iowa City (USA))

    1988-08-01

    In the rabbit cortical collecting duct (CCD), Cl tracer crosses the epithelium predominantly via an anion exchange system that operates in either a Cl-Cl or Cl-HCO{sub 3} exchange mode. In the present study, the authors used the {sup 36}Cl lumen-to-bath rate coefficient (K{sub Cl}, nm/s), a sensitive measurement of CCD transepithelial anion transport, to investigate the nature of Cl transport in the medullary collecting duct dissected from inner stripe, outer medulla (OMCD). The K{sub Cl} in OMCD perfused and bathed in HCO{sub 3}-Ringer solution was low and similar to that value observed in the CCD when anion exchange is inhibited and Cl permeates the epithelium by diffusion. To test the hypothesis that metabolic alkalosis could reverse the polarity of intercalated cells and thus induce an apical Cl-HCO{sub 3} exchanger in H{sup +}-secreting OMCD cells, they measured K{sub Cl} in OMCD from rabbits make alkalotic by deoxycorticosterone and furosemide. Although the base-line K{sub Cl} was slightly higher than in OMCD from control rabbits, the value was still far lower than the K{sub Cl} under comparable conditions in CCD. They conclude (1) Cl transport across the MCD by anion exchange is immeasurably low or nonexistent; (2) unlike the CCD, Cl transport in OMCD is not responsive to cAMP; and (3) metabolic alkalosis does not induce an apical anion exchanger in OMCD, i.e., does not cause epithelial polarity reversal.

  2. New borohydride anion B6H7-

    International Nuclear Information System (INIS)

    Kuznetsov, I.Yu.; Vinitskij, D.M.; Solntsev, K.A.

    1985-01-01

    The [Ni(Bipy) 3 ] (B 6 H 7 ) 2 , (Ph 4 P)B 6 H 7 , [Ni(Phen) 3 ](B 6 H 7 ) 2 crystals (where Bipy = bipyridine, Phen = phenathroline, Ph = phenyl) are obtained via the exchange reaction with a subsequent recrystallization from aqua-acetonic and acetonic solutions. The structure is studied of a new borohydride anion B 6 H 7 - possessing a four-valence bond unique for polyhedral borohydride anions. A triangular face of boride skeleton coordinating a hydrogen atom is considerably larger than other faces, and the electron density on this hydrogen atom is evidently much higher than at the end hydride hydrogen atoms. The trend of B 6 H 7 - anion to form statistically disordered structurs testifies to a rather slight effect of the seventh hydrogen atom position on the structure pattern of the ionic crystal lattice

  3. Photoemission from tin and lead cluster anions

    International Nuclear Information System (INIS)

    Gantefoer, G.; Gausa, M.; Meiwes-Broer, K.H.; Lutz, H.O.

    1989-01-01

    Photoelectrons from mass-identified jet-cooled tin and lead cluster anions (Sn n - , Pb n - ) are detached by ultraviolet laser light (hν=3.68 eV). The photoelectron energy spectra give the detachment energies of ground state cluster anions (electron affinities) as well as excitation energies of neutral clusters in the geometry of the anions. The energy spectra for Sn n - are dominated by flat thresholds with an n-dependence similar to that of other group IV clusters. In contrast, for Pb n - we find pronounced narrow lines close to threshold, generally followed by a 0.3-1.4 eV gap which indicates closed-shell behaviour of Pb n - for nearly all n. (orig.)

  4. Clinical acid-base pathophysiology: disorders of plasma anion gap.

    Science.gov (United States)

    Moe, Orson W; Fuster, Daniel

    2003-12-01

    The plasma anion gap is a frequently used parameter in the clinical diagnosis of a variety of conditions. The commonest application of the anion gap is to classify cases of metabolic acidosis into those that do and those that do not leave unmeasured anions in the plasma. While this algorithm is useful in streamlining the diagnostic process, it should not be used solely in this fashion. The anion gap measures the difference between the unmeasured anions and unmeasured cations and thus conveys much more information to the clinician than just quantifying anions of strong acids. In this chapter, the significance of the anion gap is emphasized and several examples are given to illustrate a more analytic approach to using the clinical anion gap; these include disorders of low anion gap, respiratory alkalosis and pyroglutamic acidosis.

  5. Transport of N-acetyl-S-pentachloro-1,3-butadienylcysteine by rat renal cortex

    Energy Technology Data Exchange (ETDEWEB)

    Lock, E.A.; Odum, J.; Ormond, P.

    1986-05-01

    N-acetyl-S-pentachloro-1,3-butadienyl-L-cysteine (PCBD-NAC) is a postulated metabolite derived from glutathione conjugation of hexachloro-1,3-butadiene and is nephrotoxic in the rat. Because PCBD-NAC causes selective necrosis to the pars recta of the proximal tubule, and is an organic anion it might be expected to be transported by the renal organic anion transport system. Rat renal cortical slices were used to characterise the transport. /sup 14/C-PCBD-NAC uptake was temperature dependent and reduced by the metabolic inhibitors cyanide and iodoacetate. Probenecid and sulphinpyrazone, specific competitive inhibitors of the anion transport system, and dinitrophenol, a metabolic inhibitor as well as a competitive inhibitor of anion transport, reduced PCBD-NAC transport. Organic cations or uric acid transport inhibitors did not alter PCBD-NAC accumulation by the slices. These data are consistent with the transport of PCBD-NAC by the renal organic anion secretory system.

  6. Hofmeister effect of anions on calcium translocation by sarcoplasmic reticulum Ca2+-ATPase

    Science.gov (United States)

    Tadini-Buoninsegni, Francesco; Moncelli, Maria Rosa; Peruzzi, Niccolò; Ninham, Barry W.; Dei, Luigi; Nostro, Pierandrea Lo

    2015-10-01

    The occurrence of Hofmeister (specific ion) effects in various membrane-related physiological processes is well documented. For example the effect of anions on the transport activity of the ion pump Na+, K+-ATPase has been investigated. Here we report on specific anion effects on the ATP-dependent Ca2+ translocation by the sarcoplasmic reticulum Ca2+-ATPase (SERCA). Current measurements following ATP concentration jumps on SERCA-containing vesicles adsorbed on solid supported membranes were carried out in the presence of different potassium salts. We found that monovalent anions strongly interfere with ATP-induced Ca2+ translocation by SERCA, according to their increasing chaotropicity in the Hofmeister series. On the contrary, a significant increase in Ca2+ translocation was observed in the presence of sulphate. We suggest that the anions can affect the conformational transition between the phosphorylated intermediates E1P and E2P of the SERCA cycle. In particular, the stabilization of the E1P conformation by chaotropic anions seems to be related to their adsorption at the enzyme/water and/or at the membrane/water interface, while the more kosmotropic species affect SERCA conformation and functionality by modifying the hydration layers of the enzyme.

  7. Roles of Organic Acid Anion Secretion in Aluminium Tolerance of Higher Plants

    Science.gov (United States)

    Yang, Lin-Tong; Qi, Yi-Ping; Jiang, Huan-Xin; Chen, Li-Song

    2013-01-01

    Approximately 30% of the world's total land area and over 50% of the world's potential arable lands are acidic. Furthermore, the acidity of the soils is gradually increasing as a result of the environmental problems including some farming practices and acid rain. At mildly acidic or neutral soils, aluminium(Al) occurs primarily as insoluble deposits and is essentially biologically inactive. However, in many acidic soils throughout the tropics and subtropics, Al toxicity is a major factor limiting crop productivity. The Al-induced secretion of organic acid (OA) anions, mainly citrate, oxalate, and malate, from roots is the best documented mechanism of Al tolerance in higher plants. Increasing evidence shows that the Al-induced secretion of OA anions may be related to the following several factors, including (a) anion channels or transporters, (b) internal concentrations of OA anions in plant tissues, (d) temperature, (e) root plasma membrane (PM) H+-ATPase, (f) magnesium (Mg), and (e) phosphorus (P). Genetically modified plants and cells with higher Al tolerance by overexpressing genes for the secretion and the biosynthesis of OA anions have been obtained. In addition, some aspects needed to be further studied are also discussed. PMID:23509687

  8. Roles of Organic Acid Anion Secretion in Aluminium Tolerance of Higher Plants

    Directory of Open Access Journals (Sweden)

    Lin-Tong Yang

    2013-01-01

    Full Text Available Approximately 30% of the world’s total land area and over 50% of the world’s potential arable lands are acidic. Furthermore, the acidity of the soils is gradually increasing as a result of the environmental problems including some farming practices and acid rain. At mildly acidic or neutral soils, aluminium(Al occurs primarily as insoluble deposits and is essentially biologically inactive. However, in many acidic soils throughout the tropics and subtropics, Al toxicity is a major factor limiting crop productivity. The Al-induced secretion of organic acid (OA anions, mainly citrate, oxalate, and malate, from roots is the best documented mechanism of Al tolerance in higher plants. Increasing evidence shows that the Al-induced secretion of OA anions may be related to the following several factors, including (a anion channels or transporters, (b internal concentrations of OA anions in plant tissues, (d temperature, (e root plasma membrane (PM H+-ATPase, (f magnesium (Mg, and (e phosphorus (P. Genetically modified plants and cells with higher Al tolerance by overexpressing genes for the secretion and the biosynthesis of OA anions have been obtained. In addition, some aspects needed to be further studied are also discussed.

  9. Diuresis by intravenous administration of xanthurenic acid in rats, and inhibition by probenecid.

    Science.gov (United States)

    Uwai, Yuichi; Nakashima, Yuta; Honjo, Emi; Kawasaki, Tatsuya; Nabekura, Tomohiro

    2014-01-01

    The conjugates with sulfate and glucoside of xanthurenic acid, a tryptophan metabolite, were reported to show natriuresis. Sulfotransferase for xanthurenic acid works in the renal proximal tubule to produce the sulfate of xanthurenic acid as well as the liver, and we recently found that xanthurenic acid is a substrate of renal organic anion transporter OAT1. The purpose of this study was to examine relationship between the transport by OAT1 and diuresis related with xanthurenic acid. Drug transport experiment using Xenopus laevis oocytes represented that probenecid inhibited xanthurenic acid uptake by rat OAT1 (rOAT1). Although no diuresis was recognized by the intravenous injection of xanthurenic acid as a bolus in rats, the addition of its infusion exhibited natriuresis. Simultaneous administration of probenecid significantly decreased the urine volume and excreted amounts of sodium into urine. These findings showed the diuresis by the xanthurenic acid administration, and it was probenecid-sensitive. The rOAT1-mediated transport of xanthurenic acid might, at least in part, contribute to its diuretic effect.

  10. High Vacuum Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization reactor, it is the best way to avoid any termination of living polymers during the number of steps for the synthesis of polymers with complex structure. In this chapter, we describe the different polymerization reactors and HVTs for the purification of monomers, solvents, and other reagents for anionic polymerization as well as few model reactions for the synthesis of polymers with simple to complex structure.

  11. Organic superconductors with an incommensurate anion structure

    OpenAIRE

    Kawamoto, Tadashi; Takimiya, Kazuo

    2009-01-01

    Superconducting incommensurate organic composite crystals based on the methylenedithio-tetraselenafulvalene (MDT-TSF) series donors, where the energy band filling deviates from the usual 3/4-filled, are reviewed. The incommensurate anion potential reconstructs the Fermi surface for both (MDT-TSF)(AuI2)0.436 and (MDT-ST)(I3)0.417 neither by the fundamental anion periodicity q nor by 2q, but by 3q, where MDT-ST is 5H-2-(1,3-dithiol-2-ylidene)-1,3-diselena-4,6-dithiapentalene, and q is the recip...

  12. Recognition, Sensing and Separation of Anions

    Indian Academy of Sciences (India)

    Dr Pradyut Ghosh

    2016-11-05

    Nov 5, 2016 ... Arsenate Recognition in Aqueous Medium. Anion log K log Ka log Kb. HAsO4. 2-. 4.42. 4.35. -. H2PO4. -. 3.62. 3.62. 5.52. SO4. 2-. 3.48. 3.36. 4.73. CO3. 2-. 2.68. -. 4.04. Table 1. Association constant value of L in DMSO-d6/D2O (9:1, v/v) with different anion in DMSO-d6/D2O (1.1:1, v/v) at 298 K a: log K ...

  13. ANION GAP NO SANGUE VENOSO EM EQUINOS

    Directory of Open Access Journals (Sweden)

    Luís Carlos Ribeiro Fan

    1994-01-01

    Full Text Available RESUMO A influência do sangue venoso na determinação do anion gap foi estudada em 50 equinos adultos clinicamente sadios no município de Santa Maria, RS. Os resultados obtidos em mEq/1 foram: sódio 140 ± 2,0; potássio 4,2 ± 0,5; cloreto 102 ± 12 e bicarbonato 26,9 ± 2,0. Conclui-se que o sangue venoso pode substituir o arterial na determinação do anion gap em equinos.

  14. Cell cycle-dependent activity of the volume- and Ca2+-activated anion currents in Ehrlich lettre ascites cells

    DEFF Research Database (Denmark)

    Klausen, Thomas Kjaer; Bergdahl, Andreas; Christophersen, Palle

    2007-01-01

    Recent evidence implicates the volume-regulated anion current (VRAC) and other anion currents in control or modulation of cell cycle progression; however, the precise involvement of anion channels in this process is unclear. Here, Cl- currents in Ehrlich Lettre Ascites (ELA) cells were monitored......+ in the pipette), was unaltered from G0 to G1, but decreased in early S phase. A novel high-affinity anion channel inhibitor, the acidic di-aryl-urea NS3728, which inhibited both VRAC and CaCC, attenuated ELA cell growth, suggesting a possible mechanistic link between cell cycle progression and cell cycle......-dependent changes in the capacity for conductive Cl- transport. It is suggested that in ELA cells, entrance into the S phase requires an increase in VRAC activity and/or an increased potential for regulatory volume decrease (RVD), and at the same time a decrease in CaCC magnitude....

  15. Synthesis of azaphenanthridines via anionic ring closure

    DEFF Research Database (Denmark)

    Hansen, Henriette Møller; Lysén, M.; Begtrup, M.

    2005-01-01

    A new and convergent synthesis of azaphenanthridines via an anionic ring closure is reported. Ortho-lithiation/in situ borylation of cyanopyridines produces the corresponding cyanopyridylboronic esters, which undergo a Suzuki-Miyaura cross-coupling to give the key intermediates. Addition of lithium...

  16. Interstellar dehydrogenated PAH anions: vibrational spectra

    Science.gov (United States)

    Buragohain, Mridusmita; Pathak, Amit; Sarre, Peter; Gour, Nand Kishor

    2018-03-01

    Interstellar polycyclic aromatic hydrocarbon (PAH) molecules exist in diverse forms depending on the local physical environment. Formation of ionized PAHs (anions and cations) is favourable in the extreme conditions of the interstellar medium (ISM). Besides in their pure form, PAHs are also likely to exist in substituted forms; for example, PAHs with functional groups, dehydrogenated PAHs etc. A dehydrogenated PAH molecule might subsequently form fullerenes in the ISM as a result of ongoing chemical processes. This work presents a density functional theory (DFT) calculation on dehydrogenated PAH anions to explore the infrared emission spectra of these molecules and discuss any possible contribution towards observed IR features in the ISM. The results suggest that dehydrogenated PAH anions might be significantly contributing to the 3.3 μm region. Spectroscopic features unique to dehydrogenated PAH anions are highlighted that may be used for their possible identification in the ISM. A comparison has also been made to see the size effect on spectra of these PAHs.

  17. Experimental Detection of the Pentazole Anion, N5(-)

    National Research Council Canada - National Science Library

    Vij, Ashwani

    2002-01-01

    .... Whereas at low collision voltages the para-phenoxypentazole anion undergoes stepwise N2 elimination generating the corresponding azide and nitrene, at high collision voltages the N5(-) anion is formed...

  18. Modelling the Effects of Competing Anions on Fluoride Removal by ...

    African Journals Online (AJOL)

    NICOLAAS

    ... the physico-chemical properties of anions and their interaction with the adsorbent surface.16. Properties of anions such as the solubility, ionic radius, hydration energy and bulk diffusion coefficient are of great importance for the selective adsorption of anions.17 In our earlier study the equilibrium and thermodynamics of ...

  19. Ionic Resistance and Permselectivity Tradeoffs in Anion Exchange Membranes

    KAUST Repository

    Geise, Geoffrey M.

    2013-10-23

    Salinity gradient energy technologies, such as reverse electrodialysis (RED) and capacitive mixing based on Donnan potential (Capmix CDP), could help address the global need for noncarbon-based energy. Anion exchange membranes (AEMs) are a key component in these systems, and improved AEMs are needed in order to optimize and extend salinity gradient energy technologies. We measured ionic resistance and permselectivity properties of quaternary ammonium-functionalized AEMs based on poly(sulfone) and poly(phenylene oxide) polymer backbones and developed structure-property relationships between the transport properties and the water content and fixed charge concentration of the membranes. Ion transport and ion exclusion properties depend on the volume fraction of water in the polymer membrane, and the chemical nature of the polymer itself can influence fine-tuning of the transport properties to obtain membranes with other useful properties, such as chemical and dimensional stability. The ionic resistance of the AEMs considered in this study decreased by more than 3 orders of magnitude (i.e., from 3900 to 1.6 Ω m) and the permselectivity decreased by 6% (i.e., from 0.91 to 0.85) as the volume fraction of water in the polymer was varied by a factor of 3.8 (i.e., from 0.1 to 0.38). Water content was used to rationalize a tradeoff relationship between the permselectivity and ionic resistance of these AEMs whereby polymers with higher water content tend to have lower ionic resistance and lower permselectivity. The correlation of ion transport properties with water volume fraction and fixed charge concentration is discussed with emphasis on the importance of considering water volume fraction when interpreting ion transport data. © 2013 American Chemical Society.

  20. Interactions between anions and soil constituents

    International Nuclear Information System (INIS)

    Bolt, G.H.; Haan, F.A.M. de

    1965-01-01

    Clay mineral crystals are characterized by a non-isotropic structure, in which a pattern is recognized. It is known that the planar sides are negatively charged (as a result of the isomorphic replacement of Si 4+ by Al 3+ and/or Al 3+ by Mg 2+ ). Under certain conditions the exposed alumina groups at the edges are charged positively. The different types of interaction between ions and clay crystals may be listed as follows: (a) Cations: positive adsorption on planar side (electrostatic interaction modified by -- non-electrostatic -- specific factors); and possibly negative adsorption at positively charged edges (electrostatic effect). (b) Anions: negative adsorption (exclusion) on planar side (electrostatic effect); and positive adsorption on the edges -- in part electrostatic, if edge positively charged; furthermore chemisorption of certain anions, as e.g. PO 4 , SiO 4

  1. An intracellular anion channel critical for pigmentation.

    Science.gov (United States)

    Bellono, Nicholas W; Escobar, Iliana E; Lefkovith, Ariel J; Marks, Michael S; Oancea, Elena

    2014-12-16

    Intracellular ion channels are essential regulators of organellar and cellular function, yet the molecular identity and physiological role of many of these channels remains elusive. In particular, no ion channel has been characterized in melanosomes, organelles that produce and store the major mammalian pigment melanin. Defects in melanosome function cause albinism, characterized by vision and pigmentation deficits, impaired retinal development, and increased susceptibility to skin and eye cancers. The most common form of albinism is caused by mutations in oculocutaneous albinism II (OCA2), a melanosome-specific transmembrane protein with unknown function. Here we used direct patch-clamp of skin and eye melanosomes to identify a novel chloride-selective anion conductance mediated by OCA2 and required for melanin production. Expression of OCA2 increases organelle pH, suggesting that the chloride channel might regulate melanin synthesis by modulating melanosome pH. Thus, a melanosomal anion channel that requires OCA2 is essential for skin and eye pigmentation.

  2. Politseiuuringud kooskõlastamisele / Liivia Anion

    Index Scriptorium Estoniae

    Anion, Liivia

    2003-01-01

    1. aprillil 2003. a. moodustatud uurimistööde kooskõlastamise komisjoni tegevuse eesmärk on saada ülevaade kõrgkoolides õppivate töötajate poolt politseis korraldatavatest uurimustest, kasutada saadud infot politsei kasuks ja vältida teenistujate tööd segavate uurimuste tegemist. Komisjoni liige Liivia Anion teeb ülevaate komisjoni otsustuspädevuse valdkondadest ja töökorraldusest

  3. Sequence anatomy of mitochondrial anion carriers

    Czech Academy of Sciences Publication Activity Database

    Ježek, Petr; Ježek, Jan

    2003-01-01

    Roč. 534, 1-3 (2003), s. 15-25 ISSN 0014-5793 R&D Projects: GA AV ČR IAA5011106; GA ČR GA301/02/1215; GA MŠk ME 389 Institutional research plan: CEZ:AV0Z5011922 Keywords : mitochondrial anion carriers * carrier genomics * bioinformatics Subject RIV: CE - Biochemistry Impact factor: 3.609, year: 2003

  4. Molecular basis of claudin-17 anion selectivity.

    Science.gov (United States)

    Conrad, Marcel P; Piontek, Jörg; Günzel, Dorothee; Fromm, Michael; Krug, Susanne M

    2016-01-01

    Claudin-17 is a paracellular channel-forming tight junction protein. Unlike the cation channels claudin-2 and -15, claudin-17 forms a distinct anion-selective channel. Aim of this study was to determine the molecular basis of channel formation and charge selectivity of this protein. To achieve this, residues located in the extracellular loops (ECL) 1 and 2 of claudin-17 were substituted, preferably those whose charges differed in claudin-17 and in claudin-2 or -15. The respective mutants were stably expressed in MDCK C7 cells and their ability to form charge-selective channels was analyzed by measuring ion permeabilities and transepithelial electrical resistance. The functional data were combined with homology modeling of the claudin-17 protomer using the structure of claudin-15 as template. In ECL1, K65, R31, E48, and E44 were found to be stronger involved in Cldn17 channel function than the clustered R45, R56, R59, and R61. For K65, not only charge but also stereochemical properties were crucial for formation of the anion-selective channel. In ECL2, both Y149 and H154 were found to contribute to constitution of the anion channel in a distinct manner. In conclusion, we provide insight into the molecular mechanism of the formation of charge- and size-selective paracellular ion channels. In detail, we propose a hydrophilic furrow in the claudin-17 protomer spanning from a gap between the ends of TM2 and TM3 along R31, E48, and Y67 to a gap between K65 and S68 lining the anion channel.

  5. Revisiting the Anionic Polymerization of Methyl Ethacrylate

    Energy Technology Data Exchange (ETDEWEB)

    Kennemur, Justin G. [Department of Chemistry and Biochemistry, Florida State University, Tallahassee FL 32306-4390 USA; Bates, Frank S. [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis MN 55455-0431 USA; Hillmyer, Marc A. [Department of Chemistry, University of Minnesota, Minneapolis MN 55455-0431 USA

    2017-09-26

    Synthesis of poly(methyl ethacrylate), (PMEA), in tetrahydrofuran at -78 °C using anionic polymerization techniques results in high molar mass (>30 kg mol-1), low dispersity (1.3), and high conversion (>81%). The molar masses of a series of samples are consistent with values anticipated by the monomer-to-initiator ratio and conversion. These results represent a significant improvement to earlier reported attempts to prepare PMEA using anionic methods. Successful diblock polymerization of polystyrene-block-PMEA, (PS-PMEA), and poly(4-tert-butylstyrene)-block-PMEA, (PtBS-PMEA), is achieved through sequential anionic polymerization techniques with dispersities as low as 1.06 and segment molar fractions close to those targeted. Broad principal scattering peaks observed by small-angle X-ray scattering (SAXS) for symmetric PS-PMEA at relatively high molar mass (39 kg mol-1) suggests an effective interaction parameter (χeff) that is smaller than for PS-block-poly(methyl methacrylate). On the other hand, PtBS-PMEA block polymers form a well-ordered morphology based on SAXS measurements and is attributable to the more hydrophobic PtBS segment. These results confirm the viability of PMEA as a new constituent in the expanding suite of polymers suitable for preparing nanostructured block polymers.

  6. Ion-selective electrode and anion gap range: What should the anion gap be?

    Science.gov (United States)

    Sadjadi, Seyed-Ali; Manalo, Rendell; Jaipaul, Navin; McMillan, James

    2013-01-01

    Using flame photometry technique in the 1970s, the normal value of anion gap (AG) was determined to be 12 ± 4 meq/L. However, with introduction of the autoanalyzers using an ion-selective electrode (ISE), the anion gap value has fallen to lower levels. A retrospective study of US veterans from a single medical center was performed to determine the value of the anion gap in subjects with normal renal function and normal serum albumin and in patients with lactic acidosis and end-stage renal disease on dialysis. In 409 patients with an estimated glomerular filtration rate ≥60 mL/min/1.73 m(2) body surface area and serum albumin ≥4 g/dL, the mean AG was 7.2 ± 2 (range 3-11) meq/L. In 299 patients with lactic acidosis (lactate level ≥4 meq/L) and 68 patients with endstage renal disease on dialysis, the mean AG was 12.5 meq/L and 12.4 meq/L, respectively. A value anion gap and a possible clue to drug intoxication and paraproteinemic disorders. With the advent of ISE for measurement of analytes, the value of the anion gap has fallen. Physicians need to be aware of the normal AG value in their respective institutions, and laboratories need to have an established value for AG based on the type of instrument they are using.

  7. A predictive model for anion exclusion in compacted Na-montmorillonite

    International Nuclear Information System (INIS)

    Tournassat, C.; Appelo, C.A.J.

    2010-01-01

    Document available in extended abstract form only. In current concepts for geological disposal of radioactive wastes, anions represent potentially the highest uncertainty in the performance assessment. Anions are weakly sorbed or even repelled from the negative clay surface constitutive of buffer (montmorillonite in bentonite) or natural (e.g. Callovo-Oxfordian argillite) material in the multi-barrier systems, and thus, are transported without retardation through only part of the pore space of the clay. The reduced accessibility of the pore space in clay is termed anion exclusion. The inner structure of bentonite with its different porosities is of paramount importance for understanding how transport (by diffusion) depends on compaction and solution composition. Anion exclusion is a well known process in soil science. Its quantification and modelling in dilute clay suspension has been a matter of much research in the 50-60's. Reanalysis of these data led to the conclusion that the Modified Gouy-Chapman (MGC) theory is able to predict fairly well the experimental data in NaCl ionic background up to ∼0.01 mol L -1 when coupled to the consideration of montmorillonite quasi-crystal formation in the suspension. Despite the available knowledge on anion exclusion in dilute systems using MGC theory, there has been little effort to extend this type of approach to compacted systems. The present study aims at obtaining a prediction method for anion exclusion in bentonite with montmorillonite as the major mineral, spanning the whole range from dilute suspension to compacted material. The model considers the specific properties of montmorillonite, with water is distributed over diverse porosities with different characteristics, viz. free (bulk) pore water, a charge neutral solution, diffuse double layer water, containing an excess of cations that compensate a fraction of the clay charge, and interlayer water, which is part of the montmorillonite structure. A model

  8. Probenecid Treatment Enhances Retinal and Brain Delivery of N-4-Benzoylaminophenylsulfonylglycine, An Anionic Aldose Reductase Inhibitor

    Science.gov (United States)

    Sunkara, Gangadhar; Ayalasomayajula, Surya P.; DeRuiter, Jack; Kompella, Uday B.

    2009-01-01

    Anion efflux transporters are expected to minimize target tissue delivery of N-[4-(benzoylaminophenyl)sulfonyl]glycine (BAPSG), a novel carboxylic acid aldose reductase inhibitor, which exists as a monocarboxylate anion at physiological conditions. Therefore, the objective of this study was to determine whether BAPSG delivery to various eye tissues including the retina and the brain can be enhanced by probenecid, a competitive inhibitor of anion transporters. To determine the influence of probenecid on eye and brain distribution of BAPSG, probenecid was administered intraperitoneally (120 mg/kg body weight; i.p.) 20 minutes prior to BAPSG (50 mg/kg; i.p.) administration. Drug disposition in various eye tissues including the retina and the brain was determined at 15 min, 1, 2 and 4 hr after BAPSG dose in male Sprauge-Dawley rats. To determine whether probenecid alters plasma clearance of BAPSG, influence of probenecid (120 mg/kg; i.p.) on the plasma pharmacokinetics of intravenously administered BAPSG (15 mg/kg) was studied as well. Finally, the effect of probenecid co-administration on the ocular tissue distribution of BAPSG was assessed in rabbits following topical (eye drop) administration. Following pretreatment with probenecid in the rat study, retinal delivery at 1 hr was increased by about 11 fold (2580 vs 244 ng/gm; pprobenecid pretreatment, significant BAPSG levels were detectable in the brain (45 ± 20 ng/gm) at 1 hr, unlike controls where the drug was not detectable. Plasma concentrations, plasma elimination half-life, and total body clearance of intravenously administered BAPSG were not altered by i.p. probenecid pretreatment. In the topical dosing study, a significant decline in BAPSG delivery was observed in the iris-ciliary body but no significant changes were observed in other tissues of the anterior segment of the eye including tears. Thus, inhibition of anion transporters is a useful approach to elevate retinal and brain delivery of BAPSG. PMID

  9. Ion-selective electrode and anion gap range: What should the anion gap be?

    OpenAIRE

    Sadjadi,; Manalo,Rendell; Jaipaul,Navin; McMillan,James

    2013-01-01

    Seyed-Ali Sadjadi, Rendell Manalo, Navin Jaipaul, James McMillan Jerry L Pettis Memorial Veterans Medical Center, Loma Linda University School of Medicine, Loma Linda, CA, USA Background: Using flame photometry technique in the 1970s, the normal value of anion gap (AG) was determined to be 12 ± 4 meq/L. However, with introduction of the autoanalyzers using an ion-selective electrode (ISE), the anion gap value has fallen to lower levels. Methods: A retrospective study of US veteran...

  10. Graphene-coated polymeric anion exchangers for ion chromatography

    International Nuclear Information System (INIS)

    Zhang, Kai; Cao, Minyi; Lou, Chaoyan; Wu, Shuchao; Zhang, Peimin; Zhi, Mingyu; Zhu, Yan

    2017-01-01

    Carbonaceous stationary phases have gained much attention for their peculiar selectivity and robustness. Herein we report the fabrication and application of a graphene-coated polymeric stationary phase for anion exchange chromatography. The graphene-coated particles were fabricated by a facile evaporation-reduction method. These hydrophilic particles were proven appropriate substrates for grafting of hyperbranched condensation polymers (HBCPs) to make pellicular anion exchangers. The new phase was characterized by zeta potentials, Fourier transform infrared spectroscopy, thermogravimetry and scanning electron microscope. Frontal displacement chromatography showed that the capacities of the anion exchangers were tuned by both graphene amount and HBCPs layer count. The chromatographic performance of graphene-coated anion exchangers was demonstrated with separation of inorganic anions, organic acids, carbohydrates and amino acids. Good reproducibility was obtained by consecutive injections, indicating high chemical stability of the coating. - Highlights: • Graphene-coated polymeric particles were fabricated by a facile method. • Hyperbranched condensation polymers (HBCPs) were grafted from graphene-coated particles to make anion exchangers. • Graphene amount and HBCPs layer count had significant effects on the anion exchange capacities. • Separation of diverse anionic analytes on the anion exchangers was demonstrated. • The prepared anion exchangers exhibited high stability.

  11. Graphene-coated polymeric anion exchangers for ion chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai; Cao, Minyi; Lou, Chaoyan [Department of Chemistry, Xixi Campus, Zhejiang University, Hangzhou 310028 (China); Wu, Shuchao, E-mail: wushch2002@163.com [Zhejiang Institute of Geology and Mineral Resources, Hangzhou 310007 (China); Zhang, Peimin [Department of Chemistry, Xixi Campus, Zhejiang University, Hangzhou 310028 (China); Zhi, Mingyu [Hangzhou Vocational & Technical College, Hangzhou, 310018 (China); Zhu, Yan, E-mail: zhuyan@zju.edu.cn [Department of Chemistry, Xixi Campus, Zhejiang University, Hangzhou 310028 (China)

    2017-06-01

    Carbonaceous stationary phases have gained much attention for their peculiar selectivity and robustness. Herein we report the fabrication and application of a graphene-coated polymeric stationary phase for anion exchange chromatography. The graphene-coated particles were fabricated by a facile evaporation-reduction method. These hydrophilic particles were proven appropriate substrates for grafting of hyperbranched condensation polymers (HBCPs) to make pellicular anion exchangers. The new phase was characterized by zeta potentials, Fourier transform infrared spectroscopy, thermogravimetry and scanning electron microscope. Frontal displacement chromatography showed that the capacities of the anion exchangers were tuned by both graphene amount and HBCPs layer count. The chromatographic performance of graphene-coated anion exchangers was demonstrated with separation of inorganic anions, organic acids, carbohydrates and amino acids. Good reproducibility was obtained by consecutive injections, indicating high chemical stability of the coating. - Highlights: • Graphene-coated polymeric particles were fabricated by a facile method. • Hyperbranched condensation polymers (HBCPs) were grafted from graphene-coated particles to make anion exchangers. • Graphene amount and HBCPs layer count had significant effects on the anion exchange capacities. • Separation of diverse anionic analytes on the anion exchangers was demonstrated. • The prepared anion exchangers exhibited high stability.

  12. Probes for anionic cell surface detection

    Science.gov (United States)

    Smith, Bradley D.

    2013-03-05

    Embodiments of the present invention are generally directed to compositions comprising a class of molecular probes for detecting the presence of anionic cell surfaces. Embodiments include compositions that are enriched for these compositions and preparations, particularly preparations suitable for use as laboratory/clinical reagents and diagnostic indicators, either alone or as part of a kit. An embodiment of the invention provides for a highly selective agent useful in the discernment and identification of dead or dying cells, such as apoptotic cells, in a relatively calcium-free environment. An embodiment of the invention provides a selective agent for the identification of bacteria in a mixed population of bacterial cells and nonbacterial cells.

  13. Recognition and sensing of fluoride anion.

    Science.gov (United States)

    Cametti, Massimo; Rissanen, Kari

    2009-05-28

    Fluoride anion recognition is attracting a mounting interest in the scientific community due to its duplicitous nature. It is a useful chemical for many industrial applications, and it has been used in human diet, but, recently it has been accused for several human pathologies. Here we describe the ample panorama of different approaches the chemists world-wide have employed to face the challenge of fluoride binding, and we outline some of the research which in our view can contribute to the development of this field, especially when fluoride binding has to be achieved in highly competitive protic solvents and water.

  14. Volume-sensitive anion channels mediate osmosensitive glutathione release from rat thymocytes.

    Directory of Open Access Journals (Sweden)

    Ravshan Z Sabirov

    Full Text Available Glutathione (GSH is a negatively charged tripeptide, which is a major determinant of the cellular redox state and defense against oxidative stress. It is assembled inside and degraded outside the cells and is released under various physiological and pathophysiological conditions. The GSH release mechanism is poorly understood at present. In our experiments, freshly isolated rat thymocytes were found to release GSH under normal isotonic conditions at a low rate of 0.82±0.07 attomol/cell/min and that was greatly enhanced under hypoosomotic stimulation to reach a level of 6.1±0.4 attomol/cell/min. The swelling-induced GSH release was proportional to the cell density in the suspension and was temperature-dependent with relatively low activation energy of 5.4±0.6 kcal/mol indicating a predominant diffusion mechanism of GSH translocation. The osmosensitive release of GSH was significantly inhibited by blockers of volume-sensitive outwardly rectifying (VSOR anion channel, DCPIB and phloretin. In patch-clamp experiments, osmotic swelling activated large anionic conductance with the VSOR channel phenotype. Anion replacement studies suggested that the thymic VSOR anion channel is permeable to GSH(- with the permeability ratio P(GSH/P(Cl of 0.32 for influx and 0.10 for efflux of GSH. The osmosensitive GSH release was trans-stimulated by SLCO/OATP substrates, probenecid, taurocholic acid and estrone sulfate, and inhibited by an SLC22A/OAT blocker, p-aminohippuric acid (PAH. The inhibition by PAH was additive to the effect of DCPIB or phloretin implying that PAH and DCPIB/phloretin affected separate pathways. We suggest that the VSOR anion channel constitutes a major part of the γ-glutamyl cycle in thymocytes and, in cooperation with OATP-like and OAT-like transporters, provides a pathway for the GSH efflux from osmotically swollen cells.

  15. Mechanism of ochratoxin A transport in kidney

    Energy Technology Data Exchange (ETDEWEB)

    Sokol, P.P.; Ripich, G.; Holohan, P.D.; Ross, C.R.

    1988-08-01

    The effect of the fungal metabolite (mycotoxin) Ochratoxin A (OTA) on the transport of p-amino(/sup 3/H)hippurate (PAH), a prototypic organic anion, was examined in renal brush border (BBMV) and basolateral membrane vesicles (BLMV). OTA was as effective an inhibitor of PAH uptake in both membranes as probenecid. The dose response curves for OTA in BBMV and BLMV gave IC50 values of 20 +/- 6 and 32 +/- 7 microM, respectively. The effect was specific since the transport of the organic cation N1-methylnicotinamide was not affected. The phenomenon of counterflow was studied to establish that OTA is translocated. OTA produced trans stimulation of PAH transport in both BBMV and BLMV, demonstrating that OTA is transported across both these membranes. The data suggest that OTA interacts with the PAH transport system in both BBMV and BLMV. We conclude that OTA transport in the kidney is mediated via the renal organic anion transport system.

  16. Photoelectron Spectroscopy and Theoretical Studies of Anion-pi Interactions: Binding Strength and Anion Specificity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jian; Zhou, Bin; Sun, Zhenrong; Wang, Xue B.

    2015-01-01

    Proposed in theory and confirmed to exist, anion–π interactions have been recognized as new and important non-covalent binding forces. Despite extensive theoretical studies, numerous crystal structural identifications, and a plethora of solution phase investigations, intrinsic anion–π interaction strengths that are free from complications of condensed phases’ environments, have not been directly measured in the gas phase. Herein we present a joint photoelectron spectroscopic and theoretical study on this subject, in which tetraoxacalix[2]arene[2]triazine 1, an electron-deficient and cavity self-tunable macrocyclic was used as a charge-neutral molecular host to probe its interactions with a series of anions with distinctly different shapes and charge states (spherical halides Cl⁻, Br⁻, I⁻, linear thiocyanate SCN⁻, trigonal planar nitrate NO₃⁻, pyramidic iodate IO₃⁻, and tetrahedral sulfate SO₄²⁻). The binding energies of the resultant gaseous 1:1 complexes (1•Cl⁻,1•Br⁻, 1•I⁻, 1•SCN⁻, 1•NO₃⁻, 1•IO₃⁻ and 1•SO₄²⁻) were directly measured experimentally, exhibiting substantial non-covalent interactions with pronounced anion specific effects. The binding strengths of Cl⁻, NO₃⁻, IO₃⁻ with 1 are found to be strongest among all singly charged anions, amounting to ca. 30 kcal/mol, but only about 40% of that between 1 and SO₄²⁻. Quantum chemical calculations reveal that all anions reside in the center of the cavity of 1 with anion–π binding motif in the complexes’ optimized structures, where 1 is seen to be able to self-regulate its cavity structure to accommodate anions of different geometries and three-dimensional shapes. Electron density surface and natural bond orbital charge distribution analysis further support anion–π binding formation. The calculated binding energies of the anions and 1 nicely reproduce the experimentally estimated electron binding energy increase. This work

  17. The quantum structure of anionic hydrogen clusters

    Science.gov (United States)

    Calvo, F.; Yurtsever, E.

    2018-03-01

    A flexible and polarizable interatomic potential has been developed to model hydrogen clusters interacting with one hydrogen anion, (H2)nH-, in a broad range of sizes n = 1-54 and parametrized against coupled cluster quantum chemical calculations. Using path-integral molecular dynamics simulations at 1 K initiated from the putative classical global minima, the equilibrium structures are found to generally rely on icosahedral shells with the hydrogen molecules pointing toward the anion, producing geometric magic numbers at sizes n = 12, 32, and 44 that are in agreement with recent mass spectrometry measurements. The energetic stability of the clusters is also connected with the extent of vibrational delocalization, measured here by the fluctuations among inherent structures hidden in the vibrational wave function. As the clusters grow, the outer molecules become increasingly free to rotate, and strong finite size effects are also found between magic numbers, associated with more prominent vibrational delocalization. The effective icosahedral structure of the 44-molecule cluster is found to originate from quantum nuclear effects as well, the classical structure showing no particular symmetry.

  18. An intracellular anion channel critical for pigmentation

    Science.gov (United States)

    Bellono, Nicholas W; Escobar, Iliana E; Lefkovith, Ariel J; Marks, Michael S; Oancea, Elena

    2014-01-01

    Intracellular ion channels are essential regulators of organellar and cellular function, yet the molecular identity and physiological role of many of these channels remains elusive. In particular, no ion channel has been characterized in melanosomes, organelles that produce and store the major mammalian pigment melanin. Defects in melanosome function cause albinism, characterized by vision and pigmentation deficits, impaired retinal development, and increased susceptibility to skin and eye cancers. The most common form of albinism is caused by mutations in oculocutaneous albinism II (OCA2), a melanosome-specific transmembrane protein with unknown function. Here we used direct patch-clamp of skin and eye melanosomes to identify a novel chloride-selective anion conductance mediated by OCA2 and required for melanin production. Expression of OCA2 increases organelle pH, suggesting that the chloride channel might regulate melanin synthesis by modulating melanosome pH. Thus, a melanosomal anion channel that requires OCA2 is essential for skin and eye pigmentation. DOI: http://dx.doi.org/10.7554/eLife.04543.001 PMID:25513726

  19. Isobar Separator for Anions: Current status

    International Nuclear Information System (INIS)

    Alary, Jean-François; Javahery, Gholamreza; Kieser, William; Zhao, Xiao-Lei; Litherland, Albert; Cousins, Lisa; Charles, Christopher

    2015-01-01

    The Isobar Separator for Anions (ISA) is an emerging separation technique of isobars applied first to the selective removal of 36 S from 36 Cl, achieving a relative suppression ratio of 6 orders of magnitude. Using a radio-frequency quadrupole (RFQ) column incorporating low energy gas cells, this innovative technique enables the use of a wide range of low energy ion–molecule reactions and collisional-induced dissociation processes for suppressing specific atomic of molecular anions with a high degree of selectivity. Other elemental pairs (analyte/isobar) successfully separated at AMS level include Ca/K, Sr/(Y, Zr), Cs/Ba, Hf/W and Pu/U. In view of these initial successes, an effort to develop a version of the ISA that can be used as a robust technique for routine AMS analysis has been undertaken. We will discuss the detailed layout of a practical ISA and the functional requirements that a combined ISA/AMS should meet. These concepts are currently being integrated in a pre-commercial ISA system that will be installed soon at the newly established A.E. Lalonde Laboratory in Ottawa, Canada.

  20. Isobar Separator for Anions: Current status

    Energy Technology Data Exchange (ETDEWEB)

    Alary, Jean-François, E-mail: alaryjf@isobarex.ca [Isobarex Corp., 32 Nixon Road Unit #1, Bolton, ON L7E 1W2 (Canada); Javahery, Gholamreza [IONICS Mass Spectrometry, 32 Nixon Road Unit #1, Bolton, ON L7E 1W2 (Canada); Kieser, William; Zhao, Xiao-Lei [Andre E. Lalonde Accelerator Mass Spectrometry Laboratory, Advanced Research Complex, University of Ottawa, 25 Templeton Street, Ottawa, ON K1N 6N5 (Canada); Litherland, Albert [IsoTrace Laboratory, Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3B1 (Canada); Cousins, Lisa [IONICS Mass Spectrometry, 32 Nixon Road Unit #1, Bolton, ON L7E 1W2 (Canada); Charles, Christopher [Andre E. Lalonde Accelerator Mass Spectrometry Laboratory, Advanced Research Complex, University of Ottawa, 25 Templeton Street, Ottawa, ON K1N 6N5 (Canada)

    2015-10-15

    The Isobar Separator for Anions (ISA) is an emerging separation technique of isobars applied first to the selective removal of {sup 36}S from {sup 36}Cl, achieving a relative suppression ratio of 6 orders of magnitude. Using a radio-frequency quadrupole (RFQ) column incorporating low energy gas cells, this innovative technique enables the use of a wide range of low energy ion–molecule reactions and collisional-induced dissociation processes for suppressing specific atomic of molecular anions with a high degree of selectivity. Other elemental pairs (analyte/isobar) successfully separated at AMS level include Ca/K, Sr/(Y, Zr), Cs/Ba, Hf/W and Pu/U. In view of these initial successes, an effort to develop a version of the ISA that can be used as a robust technique for routine AMS analysis has been undertaken. We will discuss the detailed layout of a practical ISA and the functional requirements that a combined ISA/AMS should meet. These concepts are currently being integrated in a pre-commercial ISA system that will be installed soon at the newly established A.E. Lalonde Laboratory in Ottawa, Canada.

  1. Anion photoelectron spectroscopy of radicals and clusters

    Energy Technology Data Exchange (ETDEWEB)

    Travis, Taylor R. [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    Anion photoelectron spectroscopy is used to study free radicals and clusters. The low-lying 2Σ and 2π states of C2nH (n = 1--4) have been studied. The anion photoelectron spectra yielded electron affinities, term values, and vibrational frequencies for these combustion and astrophysically relevant species. Photoelectron angular distributions allowed the author to correctly assign the electronic symmetry of the ground and first excited states and to assess the degree of vibronic coupling in C2H and C4H. Other radicals studied include NCN and I3. The author was able to observe the low-lying singlet and triplet states of NCN for the first time. Measurement of the electron affinity of I3 revealed that it has a bound ground state and attachment of an argon atom to this moiety enabled him to resolve the symmetric stretching progression.

  2. Ion-selective electrode and anion gap range: What should the anion gap be?

    Directory of Open Access Journals (Sweden)

    Sadjadi SA

    2013-06-01

    Full Text Available Seyed-Ali Sadjadi, Rendell Manalo, Navin Jaipaul, James McMillan Jerry L Pettis Memorial Veterans Medical Center, Loma Linda University School of Medicine, Loma Linda, CA, USA Background: Using flame photometry technique in the 1970s, the normal value of anion gap (AG was determined to be 12 ± 4 meq/L. However, with introduction of the autoanalyzers using an ion-selective electrode (ISE, the anion gap value has fallen to lower levels. Methods: A retrospective study of US veterans from a single medical center was performed to determine the value of the anion gap in subjects with normal renal function and normal serum albumin and in patients with lactic acidosis and end-stage renal disease on dialysis. Results: In 409 patients with an estimated glomerular filtration rate ≥60 mL/min/1.73 m2 body surface area and serum albumin ≥4 g/dL, the mean AG was 7.2 ± 2 (range 3–11 meq/L. In 299 patients with lactic acidosis (lactate level ≥4 meq/L and 68 patients with end-stage renal disease on dialysis, the mean AG was 12.5 meq/L and 12.4 meq/L, respectively. A value <2 meq/L should be considered a low anion gap and a possible clue to drug intoxication and paraproteinemic disorders. Conclusion: With the advent of ISE for measurement of analytes, the value of the anion gap has fallen. Physicians need to be aware of the normal AG value in their respective institutions, and laboratories need to have an established value for AG based on the type of instrument they are using. Keywords: acidosis, electrolytes, ESRD

  3. The TOM complex is involved in the release of superoxide anion from mitochondria.

    Science.gov (United States)

    Budzińska, Małgorzata; Gałgańska, Hanna; Karachitos, Andonis; Wojtkowska, Małgorzata; Kmita, Hanna

    2009-08-01

    Available data indicate that superoxide anion (O(2)(*-) ) is released from mitochondria, but apart from VDAC (voltage dependent anion channel), the proteins involved in its transport across the mitochondrial outer membrane still remain elusive. Using mitochondria of the yeast Saccharomyces cerevisiae mutant depleted of VDAC (Deltapor1 mutant) and the isogenic wild type, we studied the role of the TOM complex (translocase of the outer membrane) in the efflux of O(2)(*-) from the mitochondria. We found that blocking the TOM complex with the fusion protein pb(2)-DHFR decreased O(2)(*-) release, particularly in the case of Deltapor1 mitochondria. We also observed that the effect of the TOM complex blockage on O(2)(*-) release from mitochondria coincided with the levels of O(2)(*-) release as well as with levels of Tom40 expression in the mitochondria. Thus, we conclude that the TOM complex participates in O(2)(*-) release from mitochondria.

  4. Effect of CO2 absorption on ion and water mobility in an anion exchange membrane

    Science.gov (United States)

    Peng, Jing; Roy, Asa L.; Greenbaum, Steve G.; Zawodzinski, Thomas A.

    2018-03-01

    We report the measured water uptake, density, ionic conductivity and water transport properties in Tokuyama A201 membrane in OH-, HCO3- and Cl- forms. The water uptake of the AEM varies with anion type in the order λ(OH-) > λ(HCO3-) > λ(Cl-) for samples equilibrated with the same water vapor activity (aw). The conductivity of the AEM is reduced by absorption of CO2. Pulsed-field gradient nuclear magnetic resonance (PFG-NMR) measurements were utilized to characterize the diffusivity of water and HCO3- ion. The anion diffusion coefficient and membrane conductivity are used to probe the applicability of the Nernst-Einstein equation in these AEMs.

  5. Inhibition of nuclear waste solutions containing multiple aggressive anions

    International Nuclear Information System (INIS)

    Congdon, J.W.

    1987-01-01

    The inhibition of localized corrosion of carbon steel in caustic, high-level radioactive waste solutions was studied using cyclic potentiodynamic polarization scans, supplemented by partially immersed coupon tests. The electrochemical tests provided a rapid and accurate means of determining the relationship between the minimum inhibitor requirements and the concentration of the aggressive anions in this system. Nitrate, sulfate, chloride, and fluoride were identified as aggressive anions, however, no synergistic effects were observed between these anions. This observation may have important theoretical implications because it tends to contradict the behavior of aggressive anions as predicted by existing theories for localized corrosion. 10 refs., 5 figs., 2 tabs

  6. Photoinduced Dynamics of Neutral, Cationic, and Anionic Species

    DEFF Research Database (Denmark)

    Stephansen, Anne Boutrup

    electrons and subsequently transition from dipole to valence-bound anions in different energy regimes. The investigations indicate that dipole-bound anion formation depends strongly on the magnitude of the molecular dipole moment, while the formation and stability of valence-bound anions depends on ring....... Nucleobase anions are posited to be involved in DNA damage, where the molecular dipole moment of a nucleobase acts as electron-antenna and gateway for low-energy electrons to access the valence system of DNA. The investigations presented herein explore the abilities of adenine, thymine, and uracil to capture...

  7. Photoelectron Spectroscopy of 4-Bromochlorobenzene Dimer and Trimer Anions

    International Nuclear Information System (INIS)

    Kim, Namdoo

    2013-01-01

    I investigated the electron attachment to 4-BCB dimer and trimer anions using anion photoelectron spectroscopy and theoretical calculations. I found that an excess electron can be delocalized to these clusters through extended π-network. However, the nature of the ion core is different for the dimer and trimer. For the heterodimer anions, the geometry is determined by the differences in electronegativity of the molecules. Dimer anions with a large electronegativity difference have T-shaped geometries and those with a small electronegativity difference have PD geometries

  8. Oatp58Dc contributes to blood-brain barrier function by excluding organic anions from the Drosophila brain.

    Science.gov (United States)

    Seabrooke, Sara; O'Donnell, Michael J

    2013-09-01

    The blood-brain barrier (BBB) physiologically isolates the brain from the blood and, thus, plays a vital role in brain homeostasis. Ion transporters play a critical role in this process by effectively regulating access of chemicals to the brain. Organic anion-transporting polypeptides (Oatps) transport a wide range of amphipathic substrates and are involved in efflux of chemicals across the vertebrate BBB. The anatomic complexity of the vascularized vertebrate BBB, however, creates challenges for experimental analysis of these processes. The less complex structure of the Drosophila BBB facilitates measurement of solute transport. Here we investigate a physiological function for Oatp58Dc in transporting small organic anions across the BBB. We used genetic manipulation, immunocytochemistry, and molecular techniques to supplement a whole animal approach to study the BBB. For this whole animal approach, the traceable small organic anion fluorescein was injected into the hemolymph. This research shows that Oatp58Dc is involved in maintaining a chemical barrier against fluorescein permeation into the brain. Oatp58Dc expression was found in the perineurial and subperineurial glia, as well as in postmitotic neurons. We specifically targeted knockdown of Oatp58Dc expression in the perineurial and subperineurial glia to reveal that Oatp58Dc expression in the perineurial glia is necessary to maintain the barrier against fluorescein influx into the brain. Our results show that Oatp58Dc contributes to maintenance of a functional barrier against fluorescein influx past the BBB into the brain.

  9. The critical relation between chemical stability of cations and water in anion exchange membrane fuel cells environment

    Science.gov (United States)

    Dekel, Dario R.; Willdorf, Sapir; Ash, Uri; Amar, Michal; Pusara, Srdjan; Dhara, Shubhendu; Srebnik, Simcha; Diesendruck, Charles E.

    2018-01-01

    Anion exchange membrane fuel cells can potentially revolutionize energy storage and delivery; however, their commercial development is hampered by a significant technological impedance: the chemical decomposition of the anion exchange membranes during operation. The hydroxide anions, while transported from the cathode to the anode, attack the positively charged functional groups in the polymer membrane, neutralizing it and suppressing its anion-conducting capability. In recent years, several new quaternary ammonium salts have been proposed to address this challenge, but while they perform well in ex-situ chemical studies, their performance is very limited in real fuel cell studies. Here, we use experimental work, corroborated by molecular dynamics modeling to show that water concentration in the environment of the hydroxide anion, as well as temperature, significantly impact its reactivity. We compare different quaternary ammonium salts that have been previously studied and test their stabilities in the presence of relatively low hydroxide concentration in the presence of different amounts of solvating water molecules, as well as different temperatures. Remarkably, with the right amount of water and at low enough temperatures, even quaternary ammonium salts which are considered "unstable", present significantly improved lifetime.

  10. The difference between critical care initiation anion gap and prehospital admission anion gap is predictive of mortality in critical illness.

    Science.gov (United States)

    Lipnick, Michael S; Braun, Andrea B; Cheung, Joyce Ting-Wai; Gibbons, Fiona K; Christopher, Kenneth B

    2013-01-01

    We hypothesized that the delta anion gap defined as difference between critical care initiation standard anion gap and prehospital admission standard anion gap is associated with all cause mortality in the critically ill. Observational cohort study. Two hundred nine medical and surgical intensive care beds in two hospitals in Boston, MA. Eighteen thousand nine hundred eighty-five patients, age ≥18 yrs, who received critical care between 1997 and 2007. The exposure of interest was delta anion gap and categorized a priori as 10 mEq/L. Logistic regression examined death by days 30, 90, and 365 postcritical care initiation and in-hospital mortality. Adjusted odds ratios were estimated by multivariable logistic regression models. The discrimination of delta anion gap for 30-day mortality was evaluated using receiver operator characteristic curves performed for a subset of patients with all laboratory data required to analyze the data via physical chemical principles (n = 664). None. Delta anion gap was a particularly strong predictor of 30-day mortality with a significant risk gradient across delta anion gap quartiles following multivariable adjustment: delta anion gap anion gap 5-10 mEq/L odds ratio 1.56 (95% confidence interval 1.35-1.81; p anion gap >10 mEq/L odds ratio 2.18 (95% confidence interval 1.76-2.71; p anion gap 0-5 mEq/L. Similar significant robust associations post multivariable adjustments are seen with death by days 90 and 365 as well as in-hospital mortality. Correcting for albumin or limiting the cohort to patients with standard anion gap at critical care initiation of 10-18 mEq/L did not materially change the delta anion gap-mortality association. Delta anion gap has similarly moderate discriminative ability for 30-day mortality in comparison to standard base excess and strong ion gap. An increase in standard anion gap at critical care initiation relative to prehospital admission standard anion gap is a predictor of the risk of all cause patient

  11. Once upon Anion: A Tale of Photodetachment

    Science.gov (United States)

    Lineberger, W. Carl

    2013-04-01

    This contribution is very much a personal history of a journey through the wonderful world of anion chemistry, and a tale of how advances in laser technologies, theoretical methods, and computational capabilities continuously enabled advances in our understanding. It is a story of the excitement and joy that come from the opportunity to add to the fabric of science, and to do so by working as a group of excited explorers with common goals. The participants in this journey include me, my students and postdoctoral associates, my collaborators, and our many generous colleagues. It all happened, in the words of the Beatles, “with a little help from my friends.” Actually, it was so much more than a little help!

  12. Structural evolution of small ruthenium cluster anions

    Energy Technology Data Exchange (ETDEWEB)

    Waldt, Eugen [Institut für Nanotechnologie, Karlsruher Institut für Technologie, Postfach 3640, 76021 Karlsruhe (Germany); Hehn, Anna-Sophia; Ahlrichs, Reinhart [Institute für Physikalische Chemie, Karlsruher Institut für Technologie, Kaiserstrasse 12, 76128 Karlsruhe (Germany); Kappes, Manfred M.; Schooss, Detlef, E-mail: detlef.schooss@kit.edu [Institut für Nanotechnologie, Karlsruher Institut für Technologie, Postfach 3640, 76021 Karlsruhe (Germany); Institute für Physikalische Chemie, Karlsruher Institut für Technologie, Kaiserstrasse 12, 76128 Karlsruhe (Germany)

    2015-01-14

    The structures of ruthenium cluster anions have been investigated using a combination of trapped ion electron diffraction and density functional theory computations in the size range from eight to twenty atoms. In this size range, three different structural motifs are found: Ru{sub 8}{sup −}–Ru{sub 12}{sup −} have simple cubic structures, Ru{sub 13}{sup −}–Ru{sub 16}{sup −} form double layered hexagonal structures, and larger clusters form close packed motifs. For Ru{sub 17}{sup −}, we find hexagonal close packed stacking, whereas octahedral structures occur for Ru{sub 18}{sup −}–Ru{sub 20}{sup −}. Our calculations also predict simple cubic structures for the smaller clusters Ru{sub 4}{sup −}–Ru{sub 7}{sup −}, which were not accessible to electron diffraction measurements.

  13. Adsorption of an anionic dispersant on lignite

    Energy Technology Data Exchange (ETDEWEB)

    Yavuz, R.; Kucukbayrak, S. [Istanbul Technical University, Istanbul (Turkey). Dept. of Chemical Engineering, Chemical & Metallurgical Engineering Faculty

    2001-12-01

    Since coal is not a homogeneous substance but a mixture of carbonaceous materials and mineral matter, it has a variety of surface properties. Therefore, it is not easy to control the properties of coal suspensions by simply adjusting variables, such as pH and/or electrolyte. A chemical agent needs to be added to control the properties of the coal suspensions. The adsorption behavior of an anionic dispersant in the presence of a wetting agent using some Turkish lignite samples was investigated. The effects of dispersant concentration, temperature and pH on the dispersant adsorption were studied systematically, and the experimental results are presented. Pellupur B69 as a dispersant, commercial mixture of formaldehyde condensate sodium salt of naphthalene sulphonic acid, and Texapon N{sub 2}5 as a wetting agent, a sodium lauryl ether sulfate, have been used.

  14. Structures and properties of anionic clay minerals

    International Nuclear Information System (INIS)

    Koch, Chr. Bender

    1998-01-01

    The Moessbauer spectra of pyroaurite-sjoegrenite-type compounds (PTC) (layered anion exchangers) are discussed with reference to the crystal structure, cation order, and crystallite morphology. It is shown that cation-ordered layers are produced in the synthesis of carbonate and sulphate types of green rust. In contrast, synthetic and natural pyroaurite only occurs as disordered types. The redox chemistry of Fe(III) within the metal hydroxide layer is illustrated with examples of electrochemical oxidation and reversible reduction by boiling glycerol. The chemistry of iron in the interlayer is exemplified by the intercalation of Fe-cyanide complexes in hydrotalcite. This reaction may be used as a probe for the charge distribution in the interlayer

  15. Anion permselective membrane. [For redox fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, S.S.; Hodgdon, R.B.

    1978-01-01

    Experimental anion permeselective membranes were improved and characterized for use as separators in a chemical redox, power storage cell being developed at the NASA Lewis Research Center. The goal of minimal Fe/sup +3/ ion transfer was achieved for each candidate membrane system. Minimal membrane resistivity was demonstrated by reduction of film thickness using synthetic backing materials but usefulness of thin membranes was limited by the scarcity of compatible fabrics. The most durable and useful backing fabrics were modacrylics. One membrane, a copolymer of 4 vinylpyridine and vinyl benzylchloride was outstanding in overall electrochemical and physical properties. Long term (1000 hrs) membrane chemical and thermal durability in redox environment was shown by three candidate polymers and two membranes. The remainder had good durability at ambient temperature. Manufacturing capability was demonstrated for large scale production of membrane sheets 5.5 ft/sup 2/ in area for two candidate systems.

  16. Diffuse neutron scattering from anion-excess strontium chloride

    DEFF Research Database (Denmark)

    Goff, J.P.; Clausen, K.N.; Fåk, B.

    1992-01-01

    The defect structure and diffusional processes have been studied in the anion-excess fluorite (Sr, Y)Cl2.03 by diffuse neutron scattering techniques. Static cuboctahedral clusters found at ambient temperature break up at temperatures below 1050 K, where the anion disorder is highly dynamic. The a...

  17. Anion gap in hyperproteinaemia: With reference to tuberculosis ...

    African Journals Online (AJOL)

    Objectives: (1)To determine the level of electrolyte in TB patients (2) To see if these are significantly different from those of control-match for age and sex (3) To calculate the anion gap levels in TB patient and (4) to see if the anion gap levels could be used in the management of patient with tuberculosis. Patient and Methods: ...

  18. based anion exchange membrane for alkaline polymer electrolyte

    Indian Academy of Sciences (India)

    Administrator

    Alkaline polymer electrolyte fuel cell; anion exchange membrane; PPO; homogeneous quaterni- zation. 1. Introduction. Presently, alkaline polymer electrolyte fuel cells (APEFCs) using anion exchange membranes have received an immense interest among researchers (Varcoe and Slade. 2005). The advantages of ...

  19. Anion binding by biotin[6]uril in water

    DEFF Research Database (Denmark)

    Lisbjerg, Micke; Nielsen, Bjarne Enrico; Milhøj, Birgitte Olai

    2015-01-01

    In this contribution we show that the newly discovered 6 + 6 biotin-formaldehyde macrocycle Biotin[6]uril binds a variety of anionic guest molecules in water. We discuss how and why the anions are bound based on data obtained using NMR spectroscopy, mass spectrometry, isothermal titration...

  20. Protonation Reaction of Benzonitrile Radical Anion and Absorption of Product

    DEFF Research Database (Denmark)

    Holcman, Jerzy; Sehested, Knud

    1975-01-01

    The rate constant for the protonation of benzonitrile radical anions formed in pulse radiolysis of aqueous benzonitrile solutions is (3.5 ± 0.5)× 1010 dm3 mol–1 s–1. A new 270 nm absorption band is attributed to the protonated benzonitrile anion. The pK of the protonation reaction is determined t...

  1. Decreased anion gap associated with monoclonal and pseudomonoclonal gammopathy.

    Science.gov (United States)

    Frohlich, J.; Adam, W.; Golbey, M. J.; Bernstein, M.

    1976-01-01

    Nine patients with monoclonal and one with pseudomonoclonal gammopathy were found to have a decreased anion gap. Eight of the patients had multiple myeloma, one has plasma cell leukemia and one had chronic active hepatitis. In all of the the decreased anion gap was associated with an increased concentration of IgG greater than 5 g/dl. PMID:1032353

  2. Extraction of monoclonal antibodies (IgG1) using anionic and anionic/nonionic reverse micelles.

    Science.gov (United States)

    George, Daliya A; Stuckey, David C

    2010-01-01

    Purification schemes for antibody production based on affinity chromatography are trying to keep pace with increases in cell culture expression levels and many current research initiatives are focused on finding alternatives to chromatography for the purification of Monoclonal antibodies (MAbs). In this article, we have investigated an alternative separation technique based on liquid-liquid extraction called the reverse micellar extraction. We extracted MAb (IgG1) using reverse micelles of an anionic surfactant, sodium bis 2-ethyl-hexyl sulfosuccinate (AOT) and a combination of anionic (AOT) and nonionic surfactants (Brij-30, Tween-85, Span-85) using isooctane as the solvent system. The extraction efficiency of IgG1 was studied by varying parameters, such as pH of the aqueous phase, cation concentration, and type and surfactant concentration. Using the AOT/Isooctane reverse micellar system, we could achieve good overall extraction of IgG1 (between 80 and 90%), but only 30% of the bioactivity of IgG1 could be recovered at the end of the extraction by using its binding to affinity chromatography columns as a surrogate measure of activity. As anionic surfactants were suspected as being one of the reasons for the reduced activity, we decided to combine a nonionic surfactant with an anionic surfactant and then study its effect on the extraction efficiency and bioactivity. The best results were obtained using an AOT/Brij-30/Isooctane reverse micellar system, which gave an overall extraction above 90 and 59% overall activity recovery. An AOT/Tween-85/Isooctane reverse micellar system gave an overall extraction of between 75 and 80% and overall activity recovery of around 40-45%. The results showed that the activity recovery of IgG1 can be significantly enhanced using different surfactant combination systems, and if the recovery of IgG1 can be further enhanced, the technique shows considerable promise for the downstream purification of MAbs. © 2010 American Institute of

  3. Coumarin amide derivatives as fluorescence chemosensors for cyanide anions

    International Nuclear Information System (INIS)

    Wu, Qianqian; Liu, Zhiqiang; Cao, Duxia; Guan, Ruifang; Wang, Kangnan; Shan, Yanyan; Xu, Yongxiao; Ma, Lin

    2015-01-01

    Four coumarin amide derivatives with 4-methyl coumarin or pyrene as terminal group have been synthesized. Their photophysical properties and recognition properties for cyanide anions have been examined. The results indicate that the compounds can recognize cyanide anions with obvious absorption and fluorescence spectra change, at the same time, obvious color and fluorescence change can be observed by naked eye. The in situ hydrogen nuclear magnetic resonance spectra and photophysical properties change confirm that Michael additions between the chemosensors and cyanide anions take place at the 4-position of coumarin. - Highlights: • Four coumarin amide derivatives with 4-methyl coumarin or pyrene as terminal group were synthesized. • The compounds can recognize cyanide anions with obvious absorption and fluorescence spectra change. • Michael additions between the chemosensors and cyanide anions take place at the 4-position of coumarin

  4. The involvement of selected membrane transport mechanisms in the cellular uptake of 177Lu-labeled bombesin, somatostatin and gastrin analogues

    International Nuclear Information System (INIS)

    Volková, M.; Mandíková, J.; Lázníčková, A.; Lázníček, M.; Bárta, P.; Trejtnar, F.

    2015-01-01

    Introduction: Radiolabeled receptor-targeting peptides are a useful tool for the diagnostic imaging and radiotherapy of some malignancies. However, the retention of radioactivity in the kidney may result in renal radiotoxic injury. This study seeks to evaluate the role of endocytic receptor megalin, renal SLC influx transporters and fluid phase endocytosis (FPE) in the cellular accumulation of radiolabeled peptides. Methods: In vitro transport cellular studies using megalin ligands (RAP, albumin), fluid phase endocytosis (FPE) inhibitor rottlerin and low temperature were employed to evaluate the transport mechanisms of the peptides. Cells transfected with hOAT1 or hOCT2 were used to analyze the role of these SLC transporters. Somatostatin ( 177 Lu-DOTA-[Tyr 3 ]octreotate, 177 Lu-DOTA-[1-Nal 3 ]octreotide), gastrin ( 177 Lu-DOTA-sargastrin) and bombesin ( 177 Lu-DOTA-[Pro 1 ,Tyr 4 ]bombesin, 177 Lu-DOTA-[Lys 3 ]bombesin, 177 Lu-PCTA-[Lys 3 ]bombesin) analogues were involved in the study. Results: RAP, albumin and low temperature decreased the accumulation of all the studied peptides significantly. With one exception, rottlerin caused the concentration dependent inhibition of the cellular accumulation of the radiopeptides. No significant differences in the uptake of the peptides between the control cells and those transfected with hOAT1 or hOCT2 were observed. Conclusion: The study showed that active transport mechanisms are decisive for the cellular accumulation in all tested 177 Lu-labeled somatostatin, gastrin and bombesin analogues. Besides receptor-mediated endocytosis by megalin, FPE participates significantly in the uptake. The tested types of renal SLC transporters are not involved in this process

  5. The involvement of selected membrane transport mechanisms in the cellular uptake of (177)Lu-labeled bombesin, somatostatin and gastrin analogues.

    Science.gov (United States)

    Volková, M; Mandíková, J; Lázníčková, A; Lázníček, M; Bárta, P; Trejtnar, F

    2015-01-01

    Radiolabeled receptor-targeting peptides are a useful tool for the diagnostic imaging and radiotherapy of some malignancies. However, the retention of radioactivity in the kidney may result in renal radiotoxic injury. This study seeks to evaluate the role of endocytic receptor megalin, renal SLC influx transporters and fluid phase endocytosis (FPE) in the cellular accumulation of radiolabeled peptides. In vitro transport cellular studies using megalin ligands (RAP, albumin), fluid phase endocytosis (FPE) inhibitor rottlerin and low temperature were employed to evaluate the transport mechanisms of the peptides. Cells transfected with hOAT1 or hOCT2 were used to analyze the role of these SLC transporters. Somatostatin ((177)Lu-DOTA-[Tyr(3)]octreotate, (177)Lu-DOTA-[1-Nal(3)]octreotide), gastrin ((177)Lu-DOTA-sargastrin) and bombesin ((177)Lu-DOTA-[Pro(1),Tyr(4)]bombesin, (177)Lu-DOTA-[Lys(3)]bombesin, (177)Lu-PCTA-[Lys(3)]bombesin) analogues were involved in the study. RAP, albumin and low temperature decreased the accumulation of all the studied peptides significantly. With one exception, rottlerin caused the concentration dependent inhibition of the cellular accumulation of the radiopeptides. No significant differences in the uptake of the peptides between the control cells and those transfected with hOAT1 or hOCT2 were observed. The study showed that active transport mechanisms are decisive for the cellular accumulation in all tested (177)Lu-labeled somatostatin, gastrin and bombesin analogues. Besides receptor-mediated endocytosis by megalin, FPE participates significantly in the uptake. The tested types of renal SLC transporters are not involved in this process. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Importance of balancing membrane and electrode water in anion exchange membrane fuel cells

    Science.gov (United States)

    Omasta, T. J.; Wang, L.; Peng, X.; Lewis, C. A.; Varcoe, J. R.; Mustain, W. E.

    2018-01-01

    Anion exchange membrane fuel cells (AEMFCs) offer several potential advantages over proton exchange membrane fuel cells (PEMFCs), most notably to overcome the cost barrier that has slowed the growth and large scale implementation of fuel cells for transportation. However, limitations in performance have held back AEMFCs, specifically in the areas of stability, carbonation, and maximum achievable current and power densities. In order for AEMFCs to contend with PEMFCs for market viability, it is necessary to realize a competitive cell performance. This work demonstrates a new benchmark for a H2/O2 AEMFC with a peak power density of 1.4 W cm-2 at 60 °C. This was accomplished by taking a more precise look at balancing necessary membrane hydration while preventing electrode flooding, which somewhat surprisingly can occur both at the anode and the cathode. Specifically, radiation-grafted ETFE-based anion exchange membranes and anion exchange ionomer powder, functionalized with benchmark benzyltrimethylammonium groups, were utilized to examine the effects of the following parameters on AEMFC performance: feed gas flow rate, the use of hydrophobic vs. hydrophilic gas diffusion layers, and gas feed dew points.

  7. Sources of anions in aerosols in northeast Greenland during late winter

    DEFF Research Database (Denmark)

    Lauridsen, Marlene Fenger; Sørensen, Lise Lotte; Kristensen, Kasper

    2013-01-01

    affecting the composition of aerosols in the high Arctic. Therefore size-segregated aerosols were sampled at a high Arctic site, Station Nord (Northeast Greenland), in March 2009 using a Micro Orifice Uniform Deposit Impactor. The aerosol samples were extracted in order to analyse three water-soluble anions...... ), respectively. The aerosols in late winter/early spring, after polar sunrise, are found to be a mixture of long-range transported and regional to local originating aerosols. Fine particles, smaller than 1 μm, containing SO2−4 , Cl− and NO− 3 , are hypothesized to originate from long-range transport, where SO2......−4 is by far the dominating anion accounting for 50–85% of the analyzed mass. The analysis suggests that Cl− and NO−3 in coarser particles (> 1.5 μm) originate from local/regional sources. Under conditions where the air mass is transported over sea ice at high wind speeds, very coarse particles (> 18 μm...

  8. Diffusion and retention of organic anions in Callovian-Oxfordian clay rock

    International Nuclear Information System (INIS)

    Rasamimanana, Sabrina

    2016-01-01

    The Callovo-Oxfordian mud-stone (CO x ) is studied as a possible host rock for a deep disposal of radioactive waste (Cigeo project). Indeed, besides being very weakly permeable, it presents a high content of clayey minerals, capable of retaining radionuclides under cationic form and to delay strongly their transport. Nevertheless, some waste packages may release a significant amount of organic molecules, capable of complexing these radionuclides and drastically increase their mobility. So, the objective of this work was to better understand the diffusive behavior of several organic molecules of interest in this mudstone, by investigating at first their affinity with the host rock. The retention of organic molecules under anionic form (acetate, phthalate, adipate, benzoate, and citrate) was quantified on to the dispersed CO x mudstone using adsorption/desorption batch experiments. Experiments on de-carbonated rock and clay fraction only (≤ 2μm) were also performed to identify solid phases and chemical functions responsible for the retention. a correlation of the intensity of retention, R d , was pointed out whit the dipole moment μ(Orga.), providing a qualitative estimate of retention capacity for polar hydrophilic organic molecules. So, phthalate, slightly polar, displays a reversible retention (R d ≅1,6 L.kg -1 ), mainly on clayey phases. Citrate, very polar and strongly adsorbed (R d ≅ 40 L.kg -1 ), displays a persistent desorption hysteresis and an affinity to different solid phases (clayey minerals and minor oxides). Lastly, acetate, adipate and benzoate, weakly polar, display a lower affinity with rock (R d ≤ 0,2 L.kg -1 ). The diffusive behavior in compact rock of these organic anions was then studied. The effective diffusion coefficient and retardation factor values were quantified. The low diffusivity, [D e /D 0 ](Organic Anions) ≅ 0,1 a0,25 * [D e /D 0 ](Water) evidences an effect of anionic exclusion, with a same intensity as that observed for

  9. Gallium based low-interaction anions

    Science.gov (United States)

    King, Wayne A.; Kubas, Gregory J.

    2000-01-01

    The present invention provides: a composition of the formula M.sup.+x (Ga(Y).sub.4.sup.-).sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R).sub.x Q.sup.+ Ga(Y).sub.4.sup.- where Q is selected from the group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M.sup.+x.sub.y [X(Ga(Y.sub.3).sub.z ].sup.-y.sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.

  10. Anion Transport in a Chemically Stable, Sterically Bulky alpha-C Modified Imidazolium Functionalized Anion Exchange Membrane

    Science.gov (United States)

    2014-06-24

    sulfone, PSf-ImOH; poly( styrene -co-butyl methacrylate), PS-co- PBMA-Im). The chemical stabilities under alkaline conditions differ greatly. PSf-ImOH...spectroscopy ( FTIR ) was recorded on a Nicolet Nexus 470 spectrometer with an attenuated total reflectance (ATR) accessory containing a diamond...first validated by NMR and was shown to match the literature spectra.33 The FTIR spectra (Figure 2) of polyphenylene oxide, The Journal of Physical

  11. Early anion gap metabolic acidosis in acetaminophen overdose.

    Science.gov (United States)

    Zein, Joe G; Wallace, David J; Kinasewitz, Gary; Toubia, Nagib; Kakoulas, Christine

    2010-09-01

    The study aimed to determine the incidence and clinical significance of early high (>15 mEq/L) anion gap metabolic acidosis in acetaminophen (APAP) overdose. A retrospective review of a cohort of 74 patients presenting within 24 hours of APAP overdose was conducted. Early high anion gap metabolic acidosis was present in 41% of patients on admission and persisted for 1.5 ± 0.1 days. The anion gap was associated with an elevated lactate level (4.5 ± 1 mmol/L) (r(2) = 0.66, P anion gap had a higher incidence of confusion (48% vs 3%; P anion gap metabolic acidosis was found in the absence of shock or liver failure. All patients were treated with N-acetylcysteine and, despite the early high anion gap metabolic acidosis, none developed hepatic failure or hypoglycemia. Early high anion gap metabolic acidosis in patients with APAP overdose is self-limited and does not predict clinical or laboratory outcomes. Persistent or late metabolic acidosis in the absence of liver failure is not likely due to APAP and should prompt a search for other causes of metabolic acidosis. Finally, APAP overdose should be considered in patients presenting to the emergency department with altered mental status, as this is a treatable condition when detected early. Copyright © 2010 Elsevier Inc. All rights reserved.

  12. Radiosensitization of microorganisms by radical anions

    International Nuclear Information System (INIS)

    Schubert, J.; Stegeman, H.; Swildens, M.

    1981-01-01

    Irradiation of Streptococcus faecalis in a neutral, N 2 O/Br - system leads to practically complete killing with extraordinarily low doses of irradiation, namely a D 10 of 13 Gy compared to 470 Gy in N 2 , 250 Gy in N 2 O and 160 Gy in O 2 . However, irradiation and chemical investigations demonstrated that the apparent radiosensitization in neutral, N 2 O/Br - is due mainly to bromine, Br 2 and HOBr rather than B 3 - or the radical anion, Br 2 - . For example, addition of unirradiated bacteria to a previously irradiated neutral solution of N 2 O/Br - reduces survival. The medium effects are eliminated by radiation chemical and/or chemical reactions which destroy bromine, such as occur in basic solutions, in N 2 /Br - or O 2 /Br - systems because of back reactions of Br 2 with e - sub(aq) in the former and of Br 2 with H 2 O 2 and O 2 - in the latter. Neither are medium effects produced in N 2 O/Br - systems at pH > 9. However, in N 2 /Br - the D 10 = 82 Gy compared to 160 Gy in O 2 which indicates that for S. faecalis Br 2 - is intrinsically a more effective radiosensitizing agent than oxygen. (author)

  13. Globins Scavenge Sulfur Trioxide Anion Radical*

    Science.gov (United States)

    Gardner, Paul R.; Gardner, Daniel P.; Gardner, Alexander P.

    2015-01-01

    Ferrous myoglobin was oxidized by sulfur trioxide anion radical (STAR) during the free radical chain oxidation of sulfite. Oxidation was inhibited by the STAR scavenger GSH and by the heme ligand CO. Bimolecular rate constants for the reaction of STAR with several ferrous globins and biomolecules were determined by kinetic competition. Reaction rate constants for myoglobin, hemoglobin, neuroglobin, and flavohemoglobin are large at 38, 120, 2,600, and ≥ 7,500 × 106 m−1 s−1, respectively, and correlate with redox potentials. Measured rate constants for O2, GSH, ascorbate, and NAD(P)H are also large at ∼100, 10, 130, and 30 × 106 m−1 s−1, respectively, but nevertheless allow for favorable competition by globins and a capacity for STAR scavenging in vivo. Saccharomyces cerevisiae lacking sulfite oxidase and deleted of flavohemoglobin showed an O2-dependent growth impairment with nonfermentable substrates that was exacerbated by sulfide, a precursor to mitochondrial sulfite formation. Higher O2 exposures inactivated the superoxide-sensitive mitochondrial aconitase in cells, and hypoxia elicited both aconitase and NADP+-isocitrate dehydrogenase activity losses. Roles for STAR-derived peroxysulfate radical, superoxide radical, and sulfo-NAD(P) in the mechanism of STAR toxicity and flavohemoglobin protection in yeast are suggested. PMID:26381408

  14. The role of transporters on drug therapy

    Directory of Open Access Journals (Sweden)

    . Ngatidjan

    2016-02-01

    Full Text Available ABSTRACT Pharmacodynamical studies showed that most drugs elicit their effects by acting on 3 kinds of protein molecules known as receptors, enzymes or transporters. Although their detail properties had not been explained for decades the roles of transporters in drug kinetics and dynamics has been well understood, even have been applied in the therapy. Transporters are classified into 2 major classes, the solute carriers (SLC and ATP-binding cassette (ABC families. SLC transporters do not possess ATP binding site property as those of ABC transporters. SLC transporters consist of 3 SLC subfamilies i.e. organic cation transporters (OCTs, organic anion transporters (OATs and organic anion transporting polypeptides (OATPs. In contrast, ABC transporters require ATP hydrolysis to transport substrate across cell membrane. Human ABC-transporters consist of ABCA1- 13, ABCB1-11, ABCC1-12, ABCD1-4, ABCE1, ABCF1-3 and ABCG1-8 subfamily. Although the originally funtion of transporter is to transport specific physiological substrate such as nutrient, hormone, cytokines, neurotransmitters and other physiological subtances across cell membrane the specificity is not restricted to each substrate. Drugs and other xenobiotics which have structural similarity to the physiological substrates are recognized and transported by the related transporters. The competition of them on transporters therefore may lead to the occurence of drug-drug interactions (DDI or drugphysiological substrate interaction in the drug-kinetics phase. Many transporters located in the liver, intestinal and renal epithelial cell membranes involve in the transport of endogenous substance or xenobiotics including drugs play important roles as protective barrier. Since transporters also serve as the targets of drug action it is understood that transporters play important role in the pathogenesis of diseases as well as in the drug therapy of diseases.

  15. Simultaneous determination of inorganic and organic anions by ion chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yang Soon; Joe, Ki Soo; Han, Sun Ho; Park, Soon Dal; Choi, Kwang Soon

    1999-06-01

    Four methods were investigated for the simultaneous determination of several inorganic and organic anions in aqueous solution by ion chromatography. The first is two columns coupled system. The second is the gradient elution system with an anion exchange column. The third is the system with a mixed-mode stationary phase. The fourth is the system with an anion exchange column and the eluant of low conductivity without ion suppressor. The advantages and disadvantages of individual systems were discussed. The suitable methods were proposed for the application to the samples of the nuclear power industry and the environment. (author)

  16. A Quick Reference on High Anion Gap Metabolic Acidosis.

    Science.gov (United States)

    Funes, Silvia; de Morais, Helio Autran

    2017-03-01

    High anion gap (AG) metabolic acidoses can be identified by a decrease in pH, decrease in HCO 3 - or base excess, and an increased AG. The AG represents the difference between unmeasured cations and unmeasured anions; it increases secondary to the accumulation of anions other than bicarbonate and chloride. The most common causes of high AG acidosis are renal failure, diabetic ketoacidosis, and lactic acidosis. Severe increases in concentration of phosphorus can cause hyperphosphatemic acidosis. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Sulfate anion stabilization of native ribonuclease A both by anion binding and by the Hofmeister effect.

    Science.gov (United States)

    Ramos, Carlos H I; Baldwin, Robert L

    2002-07-01

    Data are reported for T(m), the temperature midpoint of the thermal unfolding curve, of ribonuclease A, versus pH (range 2-9) and salt concentration (range 0-1 M) for two salts, Na(2)SO(4) and NaCl. The results show stabilization by sulfate via anion-specific binding in the concentration range 0-0.1 M and via the Hofmeister effect in the concentration range 0.1-1.0 M. The increase in T(m) caused by anion binding at 0.1 M sulfate is 20 degrees at pH 2 but only 1 degree at pH 9, where the net proton charge on the protein is near 0. The 10 degrees increase in T(m) between 0.1 and 1.0 M Na(2)SO(4), caused by the Hofmeister effect, is independent of pH. A striking property of the NaCl results is the absence of any significant stabilization by 0.1 M NaCl, which indicates that any Debye screening is small. pH-dependent stabilization is produced by 1 M NaCl: the increase in T(m) between 0 and 1.0 M is 14 degrees at pH 2 but only 1 degree at pH 9. The 14 degree increase at pH 2 may result from anion binding or from both binding and Debye screening. Taken together, the results for Na(2)SO(4) and NaCl show that native ribonuclease A is stabilized at low pH in the same manner as molten globule forms of cytochrome c and apomyoglobin, which are stabilized at low pH by low concentrations of sulfate but only by high concentrations of chloride.

  18. Probenecid treatment enhances retinal and brain delivery of N-4-benzoylaminophenylsulfonylglycine: an anionic aldose reductase inhibitor.

    Science.gov (United States)

    Sunkara, Gangadhar; Ayalasomayajula, Surya P; DeRuiter, Jack; Kompella, Uday B

    2010-02-15

    Anion efflux transporters are expected to minimize target tissue delivery of N-[4-(benzoylaminophenyl)sulfonyl]glycine (BAPSG), a novel carboxylic acid aldose reductase inhibitor, which exists as a monocarboxylate anion at physiological conditions. Therefore, the objective of this study was to determine whether BAPSG delivery to various eye tissues including the retina and the brain can be enhanced by probenecid, a competitive inhibitor of anion transporters. To determine the influence of probenecid on eye and brain distribution of BAPSG, probenecid was administered intraperitoneally (120 mg/kg body weight; i.p.) 20 min prior to BAPSG (50 mg/kg; i.p.) administration. Drug disposition in various eye tissues including the retina and the brain was determined at 15 min, 1, 2 and 4h after BAPSG dose in male Sprauge-Dawley rats. To determine whether probenecid alters plasma clearance of BAPSG, influence of probenecid (120 mg/kg; i.p.) on the plasma pharmacokinetics of intravenously administered BAPSG (15 mg/kg) was studied as well. Finally, the effect of probenecid co-administration on the ocular tissue distribution of BAPSG was assessed in rabbits following topical (eye drop) administration. Following pretreatment with probenecid in the rat study, retinal delivery at 1h was increased by about 11-fold (2580 ng/g vs. 244 ng/g; pprobenecid pretreatment, significant BAPSG levels were detectable in the brain (45 + or - 20 ng/g) at 1h, unlike controls where the drug was not detectable. Plasma concentrations, plasma elimination half-life, and total body clearance of intravenously administered BAPSG were not altered by i.p. probenecid pretreatment. In the topical dosing study, a significant decline in BAPSG delivery was observed in the iris-ciliary body but no significant changes were observed in other tissues of the anterior segment of the eye including tears. Thus, inhibition of anion transporters is a useful approach to elevate retinal and brain delivery of BAPSG. Copyright

  19. Expanding frontiers in materials chemistry and physics with multiple anions.

    Science.gov (United States)

    Kageyama, Hiroshi; Hayashi, Katsuro; Maeda, Kazuhiko; Attfield, J Paul; Hiroi, Zenji; Rondinelli, James M; Poeppelmeier, Kenneth R

    2018-02-22

    During the last century, inorganic oxide compounds laid foundations for materials synthesis, characterization, and technology translation by adding new functions into devices previously dominated by main-group element semiconductor compounds. Today, compounds with multiple anions beyond the single-oxide ion, such as oxyhalides and oxyhydrides, offer a new materials platform from which superior functionality may arise. Here we review the recent progress, status, and future prospects and challenges facing the development and deployment of mixed-anion compounds, focusing mainly on oxide-derived materials. We devote attention to the crucial roles that multiple anions play during synthesis, characterization, and in the physical properties of these materials. We discuss the opportunities enabled by recent advances in synthetic approaches for design of both local and overall structure, state-of-the-art characterization techniques to distinguish unique structural and chemical states, and chemical/physical properties emerging from the synergy of multiple anions for catalysis, energy conversion, and electronic materials.

  20. New anion-exchange polymers for improved separations

    International Nuclear Information System (INIS)

    Jarvinen, G.D.; Barr, M.E.; Marsh, S.F.

    1997-01-01

    Objective is to improve the understanding of how the structure of a new class of anion-exchange polymers controls the binding of anionic actinide complexes from solution. This is needed to develop practical separation systems that will reduce the cost of actinide processing operations within the DOE complex. In addition anion exchange is widely used in industry. Several new series of bifunctional anion- exchange polymers have been designed, synthesized, and tested for removing Pu(IV), Am(III), and U(VI) from nitric acid. The polymers contain a pyridinium site derived from the host poly(4-vinylpyridine) and a second cationic site attached through a chain of 2 to 6 methylene groups. The new polymers removed Pu four to ten times more efficiently than the best commercial materials

  1. An anion channel in Arabidopsis hypocotyls activated by blue light

    Science.gov (United States)

    Cho, M. H.; Spalding, E. P.; Evans, M. L. (Principal Investigator)

    1996-01-01

    A rapid, transient depolarization of the plasma membrane in seedling stems is one of the earliest effects of blue light detected in plants. It appears to play a role in transducing blue light into inhibition of hypocotyl (stem) elongation, and perhaps other responses. The possibility that activation of a Cl- conductance is part of the depolarization mechanism was raised previously and addressed here. By patch clamping hypocotyl cells isolated from dark-grown (etiolated) Arabidopsis seedlings, blue light was found to activate an anion channel residing at the plasma membrane. An anion-channel blocker commonly known as NPPB 15-nitro-2-(3-phenylpropylamino)-benzoic acid] potently and reversibly blocked this anion channel. NPPB also blocked the blue-light-induced depolarization in vivo and decreased the inhibitory effect of blue light on hypocotyl elongation. These results indicate that activation of this anion channel plays a role in transducing blue light into growth inhibition.

  2. Anions for Near-Infrared Selective Organic Salt Photovoltaics.

    Science.gov (United States)

    Traverse, Christopher J; Young, Margaret; Suddard-Bangsund, John; Patrick, Tyler; Bates, Matthew; Chen, Pei; Wingate, Brian; Lunt, Sophia Y; Anctil, Annick; Lunt, Richard R

    2017-11-27

    Organic molecular salts are an emerging and highly tunable class of materials for organic and transparent photovoltaics. In this work, we demonstrate novel phenyl borate and carborane-based anions paired with a near-infrared (NIR)-selective heptamethine cation. We further explore the effects of anion structures and functional groups on both device performance and physical properties. Changing the functional groups on the anion significantly alters the open circuit voltage and yields a clear dependence on electron withdrawing groups. Anion exchange is also shown to selectively alter the solubility and film surface energy of the resulting molecular salt, enabling the potential fabrication of solution-deposited cascade or multi-junction devices from orthogonal solvents. This study further expands the catalog and properties of organic salts for inexpensive, and stable NIR-selective molecular salt photovoltaics.

  3. Adsorption of inorganic anionic contaminants on surfactant modified minerals

    Directory of Open Access Journals (Sweden)

    MAGDALENA TOMASEVIC-CANOVIC

    2003-11-01

    Full Text Available Organo-mineral complexes were obtained by treatment of aluminosilicate minerals (zeolite, bentonite and diatomaceous earth with a primary amine (oleylamine and an alkyl ammonium salt (stearyldimethylbenzyl ammonium chloride. The modification of the zeolite surface was carried out in two steps. The first step was treatment of the zeolite with 2 M HCl. This acid treatment of the zeolite increased its affinity for neutral molecules such as surface-active amines. The second step of the modification was the adsorption of oleylamine on the acid treated zeolite. Four types of organo-mineral complexes were prepared and their anion adsorption properties were compared to those of organo-zeolite. The adsorption of sulphate, bichromate and dihydrogenphosphate anions on the organo-mineral complexes was investigated. The anion adsorption measurements showed that the most efficient adsorbent for anion water pollutants was the primary amine modified H+-form zeolite.

  4. Unmeasured anions and mortality in critically ill patients in 2016.

    Science.gov (United States)

    Kotake, Yoshifumi

    2016-01-01

    The presence of acid-base disturbances, especially metabolic acidosis may negatively affect the outcome of critically ill patients. Lactic acidosis is the most frequent etiology and has largest impact on the prognosis. Since lactate measurement might not have always been available at bedside, it had been regarded as one of the unmeasured anions. Therefore, anion gap and strong ion gap has been used to as a surrogate of lactate concentration. From this perspective, the relationship between either anion gap or strong ion gap and mortality has been explored. Then, lactate became routinely measurable at bedside and the direct comparison between directly measured lactate and these surrogate parameters can be possible. Currently available evidence suggests that directly measured lactate has larger prognostic ability for mortality than albumin-corrected anion gap and strong ion gap without lactate. In this commentary, the rationale and possible clinical implications of these findings are discussed.

  5. Approach to the Patient With a Negative Anion Gap.

    Science.gov (United States)

    Emmett, Michael

    2016-01-01

    When anion gap calculation generates a very small or negative number, an explanation must be sought. Sporadic (nonreproducible) measurement errors and systematic (reproducible) laboratory errors must be considered. If an error is ruled out, 2 general possibilities exist. A true anion gap reduction can be generated by either reduced concentrations of unmeasured anions such as albumin or increased concentrations of unmeasured cations such as magnesium, calcium, or lithium. This teaching case describes a patient with aspirin (salicylate) poisoning whose anion gap was markedly reduced (-47 mEq/L). The discussion systematically reviews the possibilities and provides the explanation for this unusual laboratory result. Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  6. Radiosensitization of microorganisms by radical anions

    International Nuclear Information System (INIS)

    Schubert, J.; Stegeman, H.; Groneman, A.

    1981-01-01

    The inactivation of Streptococcus faecalis by radiolytically generated selective inorganic radical anions was investigated. The Br 2 - radical, but not (CNS) 2 - , had a pronounced radiosensitizing action. In gamma-irradiated solutions at pH7.0, the radiosensitization of a variety of scavenging systems was studied. Among these the D 10 for N 2 /Br - was 0.082 kGy while N 2 O/CNS - = 0.35 kGy, N 2 O = 0.25 kGy, N 2 = 0.47, and O 2 = 0.16 kGy. As shown previously, inactivation in N 2 O/Br - systems is due mainly to Br 2 and HOBr. From the variation of the inactivation with pH by Br 2 - and (CNS) 2 - it was deduced that tyrosine is crucial for the survival of S. faecalis via inactivation of enzymes with essential tyrosine residues such as aldolase and lipoyl dehydrogenase which are presumably needed to make energy available for DNA repair. Studies with a variety of scavengers also revealed that the t-butanol radical produced some radiosensitization of S. faecalis while the damaging effect of e - sub(aq) was much less than OH as shown by the D 10 at pH 7.0; N 2 /t-butanol = 0.32 and N 2 /ethanol = 0.71. The radiosensitizing action of Br 2 - in a natural environment containing sewage sludge was also determined, using the faecal streptococcal group as test organisms. (author)

  7. (100) faceted anion voids in electron irradiated fluorite

    International Nuclear Information System (INIS)

    Johnson, E.

    1979-01-01

    High fluence electron irradiation of fluorite crystals in the temperature range 150 to 320 K results in formation of a simple cubic anion void superlattice. Above 320 K the damage structure changes to a random distribution of large [001] faceted anion voids. This voidage behaviour, similar to that observed in a range of irradiated metals, is discussed in terms points defect rather than conventional colour centre terminology. (Auth.)

  8. GAS-GRAIN MODELS FOR INTERSTELLAR ANION CHEMISTRY

    International Nuclear Information System (INIS)

    Cordiner, M. A.; Charnley, S. B.

    2012-01-01

    Long-chain hydrocarbon anions C n H – (n = 4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances of anionic and neutral carbon chains, with a reasonable degree of accuracy. Due to their destructive effects, the depletion of oxygen atoms onto dust results in substantially greater polyyne and anion abundances in high-density gas (with n H 2 ∼>10 5 cm –3 ). The large abundances of carbon-chain-bearing species observed in the envelopes of protostars such as L1527 can thus be explained without the need for warm carbon-chain chemistry. The C 6 H – anion-to-neutral ratio is found to be most sensitive to the atomic O and H abundances and the electron density. Therefore, as a core evolves, falling atomic abundances and rising electron densities are found to result in increasing anion-to-neutral ratios. Inclusion of cosmic-ray desorption of atoms in high-density models delays freeze-out, which results in a more temporally stable anion-to-neutral ratio, in better agreement with observations. Our models include reactions between oxygen atoms and carbon-chain anions to produce carbon-chain-oxide species C 6 O, C 7 O, HC 6 O, and HC 7 O, the abundances of which depend on the assumed branching ratios for associative electron detachment.

  9. Gas-Grain Models for Interstellar Anion Chemistry

    Science.gov (United States)

    Cordiner, M. A.; Charnely, S. B.

    2012-01-01

    Long-chain hydrocarbon anions C(sub n) H(-) (n = 4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances of anionic and neutral carbon chains, with a reasonable degree of accuracy. Due to their destructive effects, the depletion of oxygen atoms onto dust results in substantially greater polyyne and anion abundances in high-density gas (with n(sub H2) approx > / cubic cm). The large abundances of carbon-chain-bearing species observed in the envelopes of protostars such as L1527 can thus be explained without the need for warm carbon-chain chemistry. The C6H(-) anion-to-neutral ratio is found to be most sensitive to the atomic O and H abundances and the electron density. Therefore, as a core evolves, falling atomic abundances and rising electron densities are found to result in increasing anion-to-neutral ratios. Inclusion of cosmic-ray desorption of atoms in high-density models delays freeze-out, which results in a more temporally stable anion-to-neutral ratio, in better agreement with observations. Our models include reactions between oxygen atoms and carbon-chain anions to produce carbon-chain-oxide species C6O, C7O, HC6O, and HC7O, the abundances of which depend on the assumed branching ratios for associative electron detachment

  10. Photoelectron spectroscopic study of carbon aluminum hydride cluster anions

    Science.gov (United States)

    Zhang, Xinxing; Wang, Haopeng; Ganteför, Gerd; Eichhorn, Bryan W.; Kiran, Boggavarapu; Bowen, Kit H.

    2016-10-01

    Numerous previously unknown carbon aluminum hydride cluster anions were generated in the gas phase, identified by time-of-flight mass spectrometry and characterized by anion photoelectron spectroscopy, revealing their electronic structure. Density functional theory calculations on the CAl5-9H- and CAl5-7H2- found that several of them possess unusually high carbon atom coordination numbers. These cluster compositions have potential as the basis for new energetic materials.

  11. Synthesis of Pyridoacridines through Anionic Cascade Ring Closure

    DEFF Research Database (Denmark)

    Petersen, I.N.; Kristensen, Jesper Langgaard

    2014-01-01

    A new synthesis of 13-deazaascididemin (AK-37) based on a recently developed anionic cascade ring closure is presented. Although the isolated yields are modest, the approach provides ready access to new substituted derivatives of 13-deazaascididemin.......A new synthesis of 13-deazaascididemin (AK-37) based on a recently developed anionic cascade ring closure is presented. Although the isolated yields are modest, the approach provides ready access to new substituted derivatives of 13-deazaascididemin....

  12. The gecko visual pigment: the anion hypsochromic effect.

    Science.gov (United States)

    Crescitelli, F; Karvaly, B

    1991-01-01

    The 521-pigment in the retina of the Tokay gecko (Gekko gekko) readily responds to particular physical and chemical changes in its environment. When solubilized in chloride deficient state the addition of Class I anions (Cl-, Br-) induces a bathochromic shift of the absorption spectrum. Class II anions (NO3-, IO3-, N3-, OCN-, SCN-, SeCN-, N(CN)2-), which exhibit ambidental properties, cause an hypsochromic shift. Class III anions (F-, I-, NO2-, CN-, AsO3-, SO2(4-), S2O2(3-) have no spectral effect on the 521-pigment. Cations appear to have no influence on the pigment absorption and Class I anions prevent or reverse the hypsochromic shift caused by Class II anions. It is suggested that the spectral displacements reflect specific changes in the opsin conformation, which alter the immediate (dipolar) environment of the retinal chromophore. The protein conformation seems to promote excited-state processes most in the native 521-pigment state and least in the presence of Class II anions. This in turn suggests that the photosensitivity of the 521-pigment is controlled by the excited rather than by the ground-state properties of the pigment.

  13. Anion-induced N-doping of naphthalenediimide polymer semiconductor in organic thin-film transistors

    KAUST Repository

    Han, Yang

    2018-03-13

    Molecular doping is an important strategy to improve the charge transport properties of organic semiconductors in various electronic devices. Compared to p-type dopants, the development of n-type dopants is especially challenging due to poor dopant stability against atmospheric conditions. In this article, we report the n-doping of the milestone naphthalenediimide-based conjugated polymer P(NDI2OD-T2) in organic thin film transistor devices by soluble anion dopants. The addition of the dopants resulted in the formation of stable radical anions in thin films, as confirmed by EPR spectroscopy. By tuning the dopant concentration via simple solution mixing, the transistor parameters could be readily controlled. Hence the contact resistance between the electrodes and the semiconducting polymer could be significantly reduced, which resulted in the transistor behaviour approaching the desirable gate voltage-independent model. Reduced hysteresis was also observed, thanks to the trap filling by the dopant. Under optimal doping concentrations the channel on-current was increased several fold whilst the on/off ratio was simultaneously increased by around one order of magnitude. Hence doping with soluble organic salts appears to be a promising route to improve the charge transport properties of n-type organic semiconductors.

  14. Determination of sulfur anions in spent oil shale leachates by ion chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Niss, N.D.

    1989-07-01

    The leaching and transport of chemical constituents from spent oil shale disposal areas is an area of environmental concern at the present time. Sulfur-containing compounds are prevalent in spent oil shales and have the potential to leach into aqueous systems surrounding disposal sites. Computer modeling has been used in recent years to predict the transport of species in an aqueous environment. The quality of model predictions, however, depends on the validation steps taken in comparing model predictions with laboratory data on ion speciation. Further, the quality of the validation step depends on the reliability of laboratory methods in generating ion speciation data. The purpose of this study was to develop methods to separate and quantify sulfur-containing anions in spent oil shale leachates by suppressed ion chromatography. The anions studied were S{sup 2{minus}} (sulfide), SO{sup 2{minus}}{sub 3} (sulfite), SO{sup 2{minus}}{sub 4} (sulfate), SCN{sup {minus}} (thiocyanate), S{sub 2}O{sup 2{minus}}{sub 3} (thiosulfate), and S{sub 4}O{sup 2{minus}}{sub 6} (tetrathionate). After the separations were developed, a series of method-challenging experiments were performed to test the reliability of the methods and assure the development of an analytically sound product. 24 refs., 7 figs., 5 tabs.

  15. Study of the simultaneous complexation of a cation and of an anion using functionalized calixarenes

    International Nuclear Information System (INIS)

    Moli, Ch.

    2002-03-01

    The chemical reprocessing of irradiated nuclear fuels leads to the production of high-level radioactive liquid wastes which contain long-lived toxic radioelements. In the framework of the long-term management of these wastes, important research work is carried out for the separation of these radioelements for their further transmutation or immobilization inside specific matrices. These radioelements are present in acid solutions of fission products in the form of cations (cesium), anions (technetium, selenium) and molecules (iodine). Crown calixarenes have been successfully used for the extraction of cesium thanks to their exceptional selectivities. This work is mainly based on the use of the chelating properties of calixarenes for the extraction of anionic radioelements. Calixarenes functionalized by amino-carbon chains have been selected. The synthesis of amine calix[4]arenes and calix[6]arenes is described and their extractive and ionophoretic properties with respect to radioelements are shown using aqueous selective separation techniques like the liquid-liquid extraction and the supported liquid membrane transport. Technetium and selenium are extracted by amine calixarenes from a 10 -2 M aqueous solution of nitric acid. At this acidity, no selenium transport is observed, while technetium transport is efficient: the solution is quasi-totally decontaminated in 6 hours. Molecular iodine is efficiently extracted with a simple organic diluent, the 1,2-nitro-phenyl-hexyl-ether, from a strongly concentrated aqueous solution of nitric acid (HNO 3 = 3 M). The transport of iodine becomes faster and more efficient when its concentration in the solution is higher. (J.S.)

  16. Estimating unmeasured anions in critically ill patients: anion-gap, base-deficit, and strong-ion-gap.

    Science.gov (United States)

    Story, D A; Poustie, S; Bellomo, R

    2002-11-01

    We used 100 routine blood samples from critically ill patients to establish whether correcting the anion-gap and base-deficit for decreased plasma albumin improves agreement with the strong-ion-gap for estimating unmeasured anions and whether the modifications increase the proportion of samples with levels of anion-gap or base-deficit above the reference ranges. We used Bland-Altman analyses to compare the methods of estimating unmeasured ions. Compared with the strong-ion-gap, modification reduced the limits of agreement for both the anion-gap and the base-deficit. The bias for the base-deficit was also reduced but the bias for the anion-gap was increased. The proportion of samples with an anion-gap > 22 meq.l(-1) increased from 4 to 29% (p 5 meq.l(-1) increased from 8 to 42% (p < 0.001). Consequently, metabolic acidosis from unmeasured ions in critically ill patients maybe more frequent than often recognised.

  17. The bicarbonate transport metabolon.

    Science.gov (United States)

    McMurtrie, Heather L; Cleary, Haley J; Alvarez, Bernardo V; Loiselle, Frederick B; Sterling, Deborah; Morgan, Patricio E; Johnson, Danielle E; Casey, Joseph R

    2004-06-01

    To allow cells to control their pH and bicarbonate levels, cells express bicarbonate transport proteins that rapidly and selectively move bicarbonate across the plasma membrane. Physical interactions have been identified between the carbonic anhydrase isoform, CAII, and the erythrocyte membrane Cl- /HCO3(-) anion exchanger, AE1, mediated by an acidic motif in the AE1 C-terminus. We have found that the presence of CAII attached to AE1 accelerates AE1 HCO3(-) transport activity, as AE1 moves bicarbonate either into or out of the cell. In efflux mode the presence of CAII attached to AE1 will increase the local concentration of bicarbonate at the AE1 transport site. As bicarbonate is transported into the cell by AE1, the presence of CAII on the cytosolic surface accelerates transport by consumption of bicarbonate, thereby maximizing the transmembrane bicarbonate concentration gradient experienced by the AE1 molecule. Functional and physical interactions also occur between CAII and Na+/HCO3(-) co-transporter isoforms NBC1 and NBC3. All examined bicarbonate transport proteins, except the DRA (SLC26A3) Cl-/HCO3(-) exchange protein, have a consensus CAII binding site in their cytoplasmic C-terminus. Interestingly, CAII does not bind DRA. CAIV is anchored to the extracellular surface of cells via a glycosylphosphatidyl inositol linkage. We have identified extracellular regions of AE1 and NBC1 that directly interact with CAIV, to form a physical complex between the proteins. In summary, bicarbonate transporters directly interact with the CAII and CAIV carbonic anhydrases to increase the transmembrane bicarbonate flux. The complex of a bicarbonate transporter with carbonic anhydrase forms a "Bicarbonate Transport Metabolon."

  18. Impact of transporters in oral absorption

    DEFF Research Database (Denmark)

    Gram, Luise Kvisgaard; Rist, Gerda Marie; Steffansen, Bente

    2009-01-01

    was to investigate whether transporters were involved in the intestinal absorption of an organic anion A275 and to compare the impact of interactions related to transporters in the Caco-2 cell model versus the in vivo rat model of intestinal absorption. In both models, it was investigated whether intestinal...... permeation of A275 was concentration dependent and affected by inhibitors or competitive organic anions. Interactions related to transporters in intestinal permeation was clearly demonstrated in the Caco-2 cell model but was not directly evident for in vivo rat absorption. However, an observed biphasic...... in vivo absorption and a large intervariability between rats might mask a dose-dependent absorption of A275. To avoid these suggested interactions, a dose of at least 10 mg/kg, which saturates the intestinal transporters involved in A275 absorption, should be administered, but at doses below that the risk...

  19. Novel Lactate Transporters from Carboxylic Acid-Producing Rhizopus

    Science.gov (United States)

    The fungus Rhizopus is frequently used for fermentative production of lactic acid, but little is known about the mechanisms or proteins for transporting this carboxylic acid. Since transport of the lactate anion across the plasma membrane is critical to prevent acidification of the cytoplasm, we ev...

  20. Anion gap, anion gap corrected for albumin, and base deficit fail to accurately diagnose clinically significant hyperlactatemia in critically ill patients.

    Science.gov (United States)

    Chawla, Lakhmir S; Jagasia, Dhiraj; Abell, Lynn M; Seneff, Michael G; Egan, Melinda; Danino, Natale; Nguyen, Aline; Ally, Mazer; Kimmel, Paul L; Junker, Christopher

    2008-01-01

    Anion gap, anion gap corrected for serum albumin, and base deficit are often used as surrogates for measuring serum lactate. None of these surrogates is postulated to predict hyperlactatemia in the critically ill. We prospectively collected data from September 2004 through August 2005 for 1381 consecutive admissions. Patients with renal disease, ketoacidosis, or toxic ingestion were excluded. Anion gap, anion gap corrected for albumin, and base deficit were calculated for all patients. We identified 286 patients who met our inclusion or exclusion criteria. The receiver-operating characteristic area under the curve for the prediction of hyperlactatemia for anion gap, anion gap corrected for albumin, and base deficit were 0.55, 0.57, and 0.64, respectively. Anion gap, anion gap corrected for albumin, and base deficit do not predict the presence or absence of clinically significant hyperlactatemia. Serum lactate should be measured in all critically ill adults in whom hypoperfusion is suspected.

  1. Discovery of Interstellar Anions in Cepheus and Auriga

    Science.gov (United States)

    Cordiner, M. A.; Charnely, S. B.; Buckle, J. V.; Walsh, C.

    2011-01-01

    We report the detection of microwave emission lines from the hydrocarbon anion C6H(-) and its parent neutral C6H in the star-forming region LI251 A (in Cepheus), and the pre-stellar core LI512 (in Auriga). The carbon chain-bearing species C4H, HC3N, HC5N, HC7N, and C3S are also detected in large abundances. The observations of L1251A constitute the first detections of anions and long-chain polyynes and cyanopolyynes (with more than five carbon atoms) in the Cepheus Flare star-forming region, and the first detection of anions in the vicinity of a protostar outside of the Taurus molecular cloud complex, indicating a possible wider importance for anions in the chemistry of star formation. Rotational excitation temperatures have been derived from the HC3N hyperfine structure lines and are found to be 6.2 K for L1251A and 8.7 K for LI5l2. The anion-to-neutral ratios are 3.6% and 4.1%, respectively, which are within the range of values previously observed in the interstellar medium, and suggest a relative uniformity in the processes governing anion abundances in different dense interstellar clouds. This research contributes toward the growing body of evidence that carbon chain anions are relatively abundant in interstellar clouds throughout the Galaxy, but especially in the regions of relatively high density and high depletion surrounding pre-stellar cores and young, embedded protostars.

  2. Anion gap among patients of multiple myeloma and normal individuals.

    Science.gov (United States)

    Mansoor, Shireen; Siddiqui, Imran; Adil, Salman; Nabi Kakepoto, Ghulam; Fatmi, Zafar; Ghani, Farooq

    2007-02-01

    To compare the Anion gap between patients of multiple myeloma and normal individuals presenting at a tertiary care hospital. This is a matched case-control study conducted at Aga Khan University Hospital, Karachi, from July 10, 2004 to April 30, 2006. The anion gap (AG) from the medical records of the 82 diagnosed cases of multiple myeloma (MM) and 104 controls were compared. Immunoglobulins (IgG and IgA) were measured by array nephelometric assay. Staging for MM patients were performed based on Salmon-Durie method. AGs were compared by independent sample t-test. Pearson coefficient of correlation was used to correlate paraprotein IgG concentration and anion gap. : Of the 186 study subjects (82 cases and 104 controls), 70% were males and 30% were females. The mean ages of MM and controls were 59.68+/-11.94 and 60+/-9.2 years respectively. There was a significant difference in mean AG, 11.2+/-1.7 mmol/L in control group (panion gap of 8.7+/-1.7 in stage I, 7.93+/-0.47 in stage II and 5.65+/-0.31 in stage III. A significant correlation was found in IgG myeloma when anion gap was expressed as a function of the serum monoclonal protein concentration. The anion gap is significantly lower in multiple myeloma patients compared to controls. Lowered anion gap is more specific feature of the IgG type MM. We suggest that correlation of AG with the disease severity and with paraproteins concentration could potentially be useful in monitoring patients for disease progression. However, longitudinal studies are required to confirm the utility of anion gap in monitoring patients with MM.

  3. Asymmetry of inverted-topology repeats in the AE1 anion exchanger suggests an elevator-like mechanism.

    Science.gov (United States)

    Ficici, Emel; Faraldo-Gómez, José D; Jennings, Michael L; Forrest, Lucy R

    2017-12-04

    The membrane transporter anion exchanger 1 (AE1), or band 3, is a key component in the processes of carbon-dioxide transport in the blood and urinary acidification in the renal collecting duct. In both erythrocytes and the basolateral membrane of the collecting-duct α-intercalated cells, the role of AE1 is to catalyze a one-for-one exchange of chloride for bicarbonate. After decades of biochemical and functional studies, the structure of the transmembrane region of AE1, which catalyzes the anion-exchange reaction, has finally been determined. Each protomer of the AE1 dimer comprises two repeats with inverted transmembrane topologies, but the structures of these repeats differ. This asymmetry causes the putative substrate-binding site to be exposed only to the extracellular space, consistent with the expectation that anion exchange occurs via an alternating-access mechanism. Here, we hypothesize that the unknown, inward-facing conformation results from inversion of this asymmetry, and we propose a model of this state constructed using repeat-swap homology modeling. By comparing this inward-facing model with the outward-facing experimental structure, we predict that the mechanism of AE1 involves an elevator-like motion of the substrate-binding domain relative to the nearly stationary dimerization domain and to the membrane plane. This hypothesis is in qualitative agreement with a wide range of biochemical and functional data, which we review in detail, and suggests new avenues of experimentation. © 2017 Ficici et al.

  4. Asymmetry of inverted-topology repeats in the AE1 anion exchanger suggests an elevator-like mechanism

    Science.gov (United States)

    Faraldo-Gómez, José D.

    2017-01-01

    The membrane transporter anion exchanger 1 (AE1), or band 3, is a key component in the processes of carbon-dioxide transport in the blood and urinary acidification in the renal collecting duct. In both erythrocytes and the basolateral membrane of the collecting-duct α-intercalated cells, the role of AE1 is to catalyze a one-for-one exchange of chloride for bicarbonate. After decades of biochemical and functional studies, the structure of the transmembrane region of AE1, which catalyzes the anion-exchange reaction, has finally been determined. Each protomer of the AE1 dimer comprises two repeats with inverted transmembrane topologies, but the structures of these repeats differ. This asymmetry causes the putative substrate-binding site to be exposed only to the extracellular space, consistent with the expectation that anion exchange occurs via an alternating-access mechanism. Here, we hypothesize that the unknown, inward-facing conformation results from inversion of this asymmetry, and we propose a model of this state constructed using repeat-swap homology modeling. By comparing this inward-facing model with the outward-facing experimental structure, we predict that the mechanism of AE1 involves an elevator-like motion of the substrate-binding domain relative to the nearly stationary dimerization domain and to the membrane plane. This hypothesis is in qualitative agreement with a wide range of biochemical and functional data, which we review in detail, and suggests new avenues of experimentation. PMID:29167180

  5. Metal-Oxide Film Conversions Involving Large Anions

    International Nuclear Information System (INIS)

    Pretty, S.; Zhang, X.; Shoesmith, D.W.; Wren, J.C.

    2008-01-01

    The main objective of my research is to establish the mechanism and kinetics of metal-oxide film conversions involving large anions (I - , Br - , S 2- ). Within a given group, the anions will provide insight on the effect of anion size on the film conversion, while comparison of Group 6 and Group 7 anions will provide insight on the effect of anion charge. This research has a range of industrial applications, for example, hazardous radioiodine can be immobilized by reaction with Ag to yield AgI. From the perspective of public safety, radioiodine is one of the most important fission products from the uranium fuel because of its large fuel inventory, high volatility, and radiological hazard. Additionally, because of its mobility, the gaseous iodine concentration is a critical parameter for safety assessment and post-accident management. A full kinetic analysis using electrochemical techniques has been performed on the conversion of Ag 2 O to (1) AgI and (2) AgBr. (authors)

  6. Anion analysis in uranium more concentrates by ion chromatography

    International Nuclear Information System (INIS)

    Badaut, V.

    2009-01-01

    In the present exploratory study, the applicability of anionic impurities or attributing nuclear material to a certain chemical process or origin has been investigated. Anions (e.g., nitrate, sulphate, fluoride, chloride) originate from acids or salt solutions that are used for processing of solutions containing uranium or plutonium. The study focuses on uranium ore concentrates ('yellow cakes') originating from different mines. Uranium is mined from different types of ore body and depending on the type of rock, different chemical processes for leaching, dissolving and precipitating the uranium need to be applied. Consequently, the anionic patterns observed in he products of these processes (the 'ore concentrates') are different. The concentrations of different anionic species were measured by ion chromatography using conductivity detection. The results show clear differences of anion concentrations and patterns between samples from different uranium mines. Besides this, differences between sampling campaigns n a same mine were also observed indicating that the uranium ore is not homogeneous in a mine. These within-mine variations, however, were smaller than the between-mine variations. (author)

  7. Identification of inorganic anions by gas chromatography/mass spectrometry.

    Science.gov (United States)

    Sakayanagi, Masataka; Yamada, Yaeko; Sakabe, Chikako; Watanabe, Kunio; Harigaya, Yoshihiro

    2006-03-10

    Inorganic anions were identified by using gas chromatography/mass spectrometry (GC/MS). Derivatization of the anions was achieved with pentafluorobenzyl p-toluenesulphonate (PFB-Tos) as the reaction reagent and a crown ether as a phase transfer catalyst. When PFB-Br was used as the reaction reagent, the retention time of it was close to those of the derivatized inorganic anions and interfered with the analysis. In contrast, the retention time of PFB-Tos differed greatly from the PFB derivatives of the inorganic anions and the compounds of interest could be detected without interference. Although the PFB derivatives of SO4, S2O3, CO3, ClO4, and ClO3 could not be detected, the derivatives of F, Cl, Br, I, CN, OCN, SCN, N3, NO3, and NO2 were detected using PFB-Tos as the derivatizing reagent. The inorganic anions were detectable within 30 ng approximately, which is of sufficient sensitivity for use in forensic chemistry. Accurate mass number was measured for each PFB derivative by high-resolution mass spectrometry (HRMS) within a measurement error of 2 millimass units (mmu), which allowed determination of the compositional formula from the mass number. In addition, actual analysis was performed successively by our method using trial samples of matrix.

  8. REACTIVITY OF ANIONS IN INTERSTELLAR MEDIA: DETECTABILITY AND APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Senent, M. L. [Departamento de Quimica y Fisica Teoricas, Instituto de Estructura de la Materia, IEM-C.S.I.C., Serrano 121, Madrid E-28006 (Spain); Hochlaf, M., E-mail: senent@iem.cfmac.csic.es, E-mail: hochlaf@univ-mlv.fr [Laboratoire de Modelisation et Simulation Multi Echelle, Universite Paris-Est, MSME UMR 8208 CNRS, 5 boulevard Descartes, F-77454 Marne-la-Vallee (France)

    2013-05-01

    We propose a general rule to distinguish between detectable and undetectable astronomical anions. We believe that only few anions live long enough in the interstellar medium and thus can be detected. Our method is based on quantum mechanical calculations capable of describing accurately the evolution of electronic states during chemical processes. The still not fully understood reactivity at low temperatures is discussed considering non-adiabatic effects. The role of excited states has usually been neglected in previous works which basically focused on the ground electronic state for interpretations of experimental observations. Here, we deal with unsaturated carbon chains (e.g., C{sub n} H{sup -}), which show a high density of electronic states close to their corresponding ground electronic states, complex molecular dynamics, and non-adiabatic phenomena. Our general rule shows that it is not sufficient that anions exist in the gas phase (in the laboratory) to be present in media such as astrophysical media, since formation and decomposition reactions of these anions may allow the population of anionic electronic states to autodetach, forming neutrals. For C{sub n} H, reactivity depends strongly on n, where long and short chains behave differently. Formation of linear chains is relevant.

  9. Treatment of acute non-anion gap metabolic acidosis.

    Science.gov (United States)

    Kraut, Jeffrey A; Kurtz, Ira

    2015-02-01

    Acute non-anion gap metabolic acidosis, also termed hyperchloremic acidosis, is frequently detected in seriously ill patients. The most common mechanisms leading to this acid-base disorder include loss of large quantities of base secondary to diarrhea and administration of large quantities of chloride-containing solutions in the treatment of hypovolemia and various shock states. The resultant acidic milieu can cause cellular dysfunction and contribute to poor clinical outcomes. The associated change in the chloride concentration in the distal tubule lumen might also play a role in reducing the glomerular filtration rate. Administration of base is often recommended for the treatment of acute non-anion gap acidosis. Importantly, the blood pH and/or serum bicarbonate concentration to guide the initiation of treatment has not been established for this type of metabolic acidosis; and most clinicians use guidelines derived from studies of high anion gap metabolic acidosis. Therapeutic complications resulting from base administration such as volume overload, exacerbation of hypertension and reduction in ionized calcium are likely to be as common as with high anion gap metabolic acidosis. On the other hand, exacerbation of intracellular acidosis due to the excessive generation of carbon dioxide might be less frequent than in high anion gap metabolic acidosis because of better tissue perfusion and the ability to eliminate carbon dioxide. Further basic and clinical research is needed to facilitate development of evidence-based guidelines for therapy of this important and increasingly common acid-base disorder.

  10. Hybrid organic-inorganic anion-exchange pore-filled membranes for the recovery of nitric acid from highly acidic aqueous waste streams.

    Science.gov (United States)

    Chavan, Vivek; Agarwal, Chhavi; Adya, V C; Pandey, Ashok K

    2018-04-15

    Recycling of acid from aqueous waste streams is highly important not only from the environmental point of view but also for developing the sustainable technology. One of the effective ways to recover acid from aqueous waste streams is the anion-exchange membrane based diffusion-dialysis. The work presents the synthesis and characterization of anion-exchange pore-filled membranes for the objective of recovery of high concentration of acid by diffusion dialysis. The membranes were prepared by anchoring the guest organic-inorganic anionic gel in the pores of the host poly(propylene) membrane by in situ UV-initiator induced polymerization of the appropriate monomers along with cross-linker. The removal of nitric acid in the presence of different representative monovalent, divalent and trivalent nitrates and the leakage of these ions through anion exchange membrane have been studied by DD technique for optimizing the chemical composition of the membrane. The nitric acid permeation rate of the membrane with the optimized composition has been found to be considerably faster than the commercial Selemion membrane without sacrificing salt leakage. The performance of the optimized pore-filled anion exchange membranes has been found to be independent of the acid concentration, nature of the anion and substrate and has been observed to be solely dependent on the guest inorganic-organic hybrid anionic gel component. The membranes have been found to be stable and reusable for the acid recovery. Removal of nitric acid as high as 90% from the simulated high level nuclear waste with the optimized grafted pore-filled membrane has been achieved with negligible salt transport. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Cell wall bound anionic peroxidases from asparagus byproducts.

    Science.gov (United States)

    Jaramillo-Carmona, Sara; López, Sergio; Vazquez-Castilla, Sara; Jimenez-Araujo, Ana; Rodriguez-Arcos, Rocio; Guillen-Bejarano, Rafael

    2014-10-08

    Asparagus byproducts are a good source of cationic soluble peroxidases (CAP) useful for the bioremediation of phenol-contaminated wastewaters. In this study, cell wall bound peroxidases (POD) from the same byproducts have been purified and characterized. The covalent forms of POD represent >90% of the total cell wall bound POD. Isoelectric focusing showed that whereas the covalent fraction is constituted primarily by anionic isoenzymes, the ionic fraction is a mixture of anionic, neutral, and cationic isoenzymes. Covalently bound peroxidases were purified by means of ion exchange chromatography and affinity chromatography. In vitro detoxification studies showed that although CAP are more effective for the removal of 4-CP and 2,4-DCP, anionic asparagus peroxidase (AAP) is a better option for the removal of hydroxytyrosol (HT), the main phenol present in olive mill wastewaters.

  12. Synthesis and anion binding properties of porphyrins and related compounds

    KAUST Repository

    Figueira, Flávio

    2016-12-02

    Over the last two decades the preparation of pyrrole-based receptors for anion recognition has attracted considerable attention. In this regard porphyrins, phthalocyanines and expanded porphyrins have been used as strong and selective receptors while the combination of those with different techniques and materials can boost their applicability in different applications as chemosensors and extracting systems. Improvements in the field, including the synthesis of this kind of compounds, can contribute to the development of efficient, cheap, and easy-to-prepare anion receptors. Extensive efforts have been made to improve the affinity and selectivity of these compounds and the continuous expansion of related research makes this chemistry even more promising. In this review, we summarize the most recent developments in anion binding studies while outlining the strategies that may be used to synthesize and functionalize these type of macrocycles. © 2016 World Scientific Publishing Company.

  13. Coupled binding mechanism of three sodium ions and aspartate in the glutamate transporter homologue GltTk

    NARCIS (Netherlands)

    Guskov, Albert; Jensen, Sonja; Faustino, Ignacio; Marrink, Siewert J.; Slotboom, Dirk Jan

    2016-01-01

    Glutamate transporters catalyse the thermodynamically unfavourable transport of anionic amino acids across the cell membrane by coupling it to the downhill transport of cations. This coupling mechanism is still poorly understood, in part because the available crystal structures of these transporters

  14. Anion effect on the retention of recoil atom of coordination crystalline compounds

    International Nuclear Information System (INIS)

    Dimotakis, P.N.; Papadopoulos, B.P.

    1980-01-01

    The anion effect of various cobaltic crystalline compounds - having the same cation and differing in anion -on the retention of neutron activated central cobalt atom has been studied. The cation was trans-dichloro(bis)ethylenediamine cobalt(III) and the anions were simple spherical anions (Cl - , Br - , I - ), planar anions (NO 3 - ), trigonal pyramidal anions (ClO 3 - , BrO 3 - ), tetrahedral anions (SO 4 2- , CrO 4 2- , MnO 4 - ) and linear anions (SCN - ). The cobalt-60 activity after reactor irradiation either in simple Co 2+ cation or in cobaltic complex cation determined the retention values. In all irradiations at ordinary temperature and at liquid nitrogen temperature the results showed an effect of the different anions, depending on the geometry, volume and charge, on the recombination of the recoil cobalt with the ligands in the coordination sphere. (author)

  15. Interplay of vacuolar transporters for coupling primary and secondary active transport

    Directory of Open Access Journals (Sweden)

    Michèle Siek

    2016-10-01

    Full Text Available Secondary active transporters are driven by the proton motif force which is generated by primary active transporters such as the vacuolar proton pumps V-ATPase and V-PPase. The vacuole occupies up to 90 % of the mature cell and acidification of the vacuolar lumen is a challenging and energy-consuming task for the plant cell. Therefore, a direct coupling of primary and secondary active transporters is expected to enhance transport efficiency and to reduce energy consumption by transport processes across the tonoplast. This has been addressed by analyzing physical and functional interactions between the V-ATPase and a selection of vacuolar transporters including the primary active proton pump AVP1, the calcium ion/proton exchanger CAX1, the potassium ion/proton symporter KUP5, the sodium ion/proton exchanger NHX1, and the anion/proton exchanger CLC-c. Physical interaction was demonstrated in vivo for the V-ATPase and the secondary active transporters CAX1 and CLC-c, which are responsible for calcium- and anion-accumulation in the vacuole, respectively. Measurements of V-ATPase activity and vacuolar pH revealed a functional interaction of V-ATPase and CAX1, CLC-c that is likely caused by the observed physical interaction. The complex of the V-ATPase further interacts with the nitrate reductase 2, and as a result, nitrate assimilation is directly linked to the energization of vacuolar nitrate accumulation by secondary active anion/proton exchangers.

  16. Anionic solid lipid nanoparticles supported on protamine/DNA complexes

    International Nuclear Information System (INIS)

    Ye Jiesheng; Liu Chunxi; Chen Zhijin; Zhang Na; Wang Aihua

    2008-01-01

    The objective of this study was to design novel anionic ternary nanoparticles for gene delivery. These ternary nanoparticles were equipped with protamine/DNA binary complexes (150-200 nm) as the support, and the anionic formation was achieved by absorption of anionic solid lipid nanoparticles (≤20 nm) onto the surface of the binary complexes. The small solid lipid nanoparticles (SLNs) were prepared by a modified film dispersion-ultrasonication method, and adsorption of the anionic SLNs onto the binary complexes was typically carried out in water via electrostatic interaction. The formulated ternary nanoparticles were found to be relatively uniform in size (257.7 ± 10.6 nm) with a 'bumpy' surface, and the surface charge inversion from 19.28 ± 1.14 mV to -17.16 ± 1.92 mV could be considered as evidence of the formation of the ternary nanoparticles. The fluorescence intensity measurements from three batches of the ternary nanoparticles gave a mean adsorption efficiency of 96.75 ± 1.13%. Circular dichroism spectra analysis showed that the protamine/DNA complexes had been coated by small SLNs, and that the anionic ternary nanoparticles formed did not disturb the construction of the binary complexes. SYBR Green I analysis suggested that the ternary nanoparticles could protect the DNA from nuclease degradation, and cell viability assay results showed that they exhibit lower cytotoxicity to A549 cells compared with the binary complexes and lipofectamine. The transfection efficiency of the ternary nanoparticles was better than that of naked DNA and the binary complexes, and almost equal to that of lipofectamine/DNA complexes, as revealed by inversion fluorescence microscope observation. These results indicated that the anionic ternary nanoparticles could facilitate gene transfer in cultured cells, and might alleviate the drawbacks of the conventional cationic vector/DNA complexes for gene delivery in vivo

  17. Anion exchange separation and purification of neodymium from fission products

    International Nuclear Information System (INIS)

    Ramkumar, K.L.; Raman, V.A.; Khodade, P.S.; Jain, H.C.

    1979-01-01

    Neodymium-148, the stable fission product has been proved to be one of the best monitors for the determination of nuclear fuel burn-up using triple spike isotope dilution mass spectrometry. For the precise and accurate determination of neodymium it is essential to separate it from bulk of other materials and purify from cerium and samarium which would otherwise cause isobaric interferences. A single stage anion exchange procedure for the separation and purification of neodymium from fission products has been developed. This method supercedes the lengthy and time consuming two stage anion exchange procedure normally used and ensures good chemical yield. (author)

  18. Direct infrared observation of hydrogen chloride anions in solid argon.

    Science.gov (United States)

    Huang, Tzu-Ping; Chen, Hui-Fen; Liu, Meng-Chen; Chin, Chih-Hao; Durrant, Marcus C; Lee, Yin-Yu; Wu, Yu-Jong

    2017-09-21

    To facilitate direct spectroscopic observation of hydrogen chloride anions (HCl - ), electron bombardment of CH 3 Cl diluted in excess Ar during matrix deposition was used to generate this anion. Subsequent characterization were performed by IR spectroscopy and quantum chemical calculations. Moreover the band intensity of HCl - decays slowly when the matrix sample is maintained in the dark for a prolonged time. High-level ab inito calculation suggested that HCl - is only weakly bound. Atom-in-molecule charge analysis indicated that both atoms of HCl - are negatively charged and the Cl atom is hypervalent.

  19. Derivatives of Dodecahalo-Closo-Dodecaborate Di-Anion

    OpenAIRE

    Avelar, Amy Cindy

    2009-01-01

    ABSTRACT OF THE DISSERTATIONDerivatives of the Dodecahalo-Closo-Dodecaborate Di-AnionbyAmy AvelarDoctor of Philosophy, Graduate Program in ChemistryUniversity of California, Riverside, December 2009Dr. Christopher A. Reed, ChairpersonThe di-anion, dodecahalo-closo-dodecaborate, B12X122-, where the X = Cl or Br, has been determined to be a useful weakly coordinating anion, WCA. Despite the di- negative charge, several elusive and reactive cationic species were stabilized with B12X122- as the c...

  20. Photoelectron spectroscopy of boron aluminum hydride cluster anions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H., E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Li, Xiang [Center for Space Science and Technology, University of Maryland–Baltimore County, Baltimore, Maryland 21250 (United States); Kiran, Boggavarapu, E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry and Physics, McNeese State University, Lake Charles, Louisiana 70609 (United States); Kandalam, Anil K. [Department of Physics, West Chester University, West Chester, Pennsylvania 19383 (United States)

    2014-04-28

    Boron aluminum hydride clusters are studied through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations. Boron aluminum hydride cluster anions, B{sub x}Al{sub y}H{sub z}{sup −}, were generated in a pulsed arc cluster ionization source and identified by time-of-flight mass spectrometry. After mass selection, their photoelectron spectra were measured by a magnetic bottle-type electron energy analyzer. The resultant photoelectron spectra as well as calculations on a selected series of stoichiometries reveal significant geometrical changes upon substitution of aluminum atoms by boron atoms.

  1. Photoelectron spectroscopy of boron aluminum hydride cluster anions.

    Science.gov (United States)

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H; Li, Xiang; Kiran, Boggavarapu; Kandalam, Anil K

    2014-04-28

    Boron aluminum hydride clusters are studied through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations. Boron aluminum hydride cluster anions, BxAlyHz(-), were generated in a pulsed arc cluster ionization source and identified by time-of-flight mass spectrometry. After mass selection, their photoelectron spectra were measured by a magnetic bottle-type electron energy analyzer. The resultant photoelectron spectra as well as calculations on a selected series of stoichiometries reveal significant geometrical changes upon substitution of aluminum atoms by boron atoms.

  2. A study of model systems in anionic exchange

    International Nuclear Information System (INIS)

    Haegele, R.; Boeyens, J.C.A.

    1977-01-01

    Preliminary experiments are reported on the preparation and characterization of anionic sulphate and chloride complexes of UO 2+ 2 and iron(III), benzyl-trimethylammonium cation being used as a model substance for the simulation of positive sites in an anionic-exchange resin. The structure of (BTMA) 4 [UO 2 CL 3 -O 2 -CL 3 UO 2 ], a binuclear uranyl-peroxocomplex that has not been reported in the literature, was elucidated by single-crystal x-ray examination, and is described and discussed [af

  3. Electrokinetic remediation of anionic contaminants from unsaturated soils

    International Nuclear Information System (INIS)

    Lindgren, E.R.; Kozak, M.W.; Mattson, E.D.

    1992-01-01

    Heavy-metal contamination of soil and groundwater is a widespread problem in the DOE weapons complex, and for the nation as a whole. Electrokinetic remediation is one possible technique for in situ removal of such contaminants from unsaturated soils. In previous studies at Sandia National Laboratories, the electromigration of chromate ions and anionic dye ions have been demonstrated. This paper reports on a series of experiments that were conducted to study the effect of moisture content on the electromigration rate of anionic contaminants in unsaturated soil and determine the limiting moisture content for which electromigration occurs

  4. Uranium extraction from sulfuric acid solution using anion exchange resin

    International Nuclear Information System (INIS)

    Sheta, M. E.; Abdel Aal, M. M.; Kandil, A. T.

    2012-12-01

    Uranium is currently recovered from sulfuric acid leach liquor using anion exchange resin as Amberlite IRA 402 (CT). This technology is based on fact that, uranium exists as anionic complexes. This takes place by controlling the pH of the solution, agitation time, temperature and resin to solution ratio (R/S). In this work, batch stirrer tank used for uranium extraction from sulfate medium and after extraction, elution process was done using 1M NaCl solution. After extraction and elution process, the resin was separated from the system and uranium was determined in the solution. (Author)

  5. Photodetachment and Doppler laser cooling of anionic molecules

    Science.gov (United States)

    Gerber, Sebastian; Fesel, Julian; Doser, Michael; Comparat, Daniel

    2018-02-01

    We propose to extend laser-cooling techniques, so far only achieved for neutral molecules, to molecular anions. A detailed computational study is performed for {{{C}}}2- molecules stored in Penning traps using GPU based Monte Carlo simulations. Two cooling schemes—Doppler laser cooling and photodetachment cooling—are investigated. The sympathetic cooling of antiprotons is studied for the Doppler cooling scheme, where it is shown that cooling of antiprotons to subKelvin temperatures could becomes feasible, with impacts on the field of antimatter physics. The presented cooling schemes also have applications for the generation of cold, negatively charged particle sources and for the sympathetic cooling of other molecular anions.

  6. A Quick Reference on Anion Gap and Strong Ion Gap.

    Science.gov (United States)

    Torrente Artero, Carlos

    2017-03-01

    Metabolic acid-base disorders are common in emergency and critically ill patients. Clinicians may have difficulty recognizing their presence when multiple acid-base derangements are present in a single patient simultaneously. The anion gap and the strong ion gap concepts are useful calculations to identify the components of complex metabolic acid-base associated to the presence of unmeasured anions. This article presents their definition, normal values, indications, limitations, and guidelines for interpretation of changes in the clinical setting. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Preparation of Cationic MOFs with Mobile Anions by Anion Stripping to Remove 2,4-D from Water

    Directory of Open Access Journals (Sweden)

    Tao Chen

    2017-07-01

    Full Text Available A cationic porous framework with mobile anions (MIL-101(Cr-Cl was easily and successfully synthesized by utilizing the stronger affinity of F− to Al3+ than Cr3+ in the charge-balanced framework of MIL-101(Cr. The structure, morphology and porosity of MIL-101(Cr-Cl were characterized. The obtained new materials retain the high surface area, good thermostability, and structure topology of MIL-101(Cr. With the mobile Cl− anion, MIL-101(Cr-Cl can be used as an ion-exchange material for anionic organic pollutions. In this work, 2,4-dichlorophenoxyacetic acid (2,4-D was used as a model to test the absorption performance of this new material. This new material exhibited improved adsorbability compared to that of the original metal-organic frameworks (MOFs. At the same time, this material also shows high anti-interference performance with changing solution pH.

  8. Charge transport and structure in semimetallic polymers

    DEFF Research Database (Denmark)

    Rudd, Sam; Franco-Gonzalez, Juan F.; Kumar Singh, Sandeep

    2017-01-01

    Owing to changes in their chemistry and structure, polymers can be fabricated to demonstrate vastly different electrical conductivities over many orders of magnitude. At the high end of conductivity is the class of conducting polymers, which are ideal candidates for many applications in low......-cost electronics. Here, we report the influence of the nature of the doping anion at high doping levels within the semi-metallic conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) on its electronic transport properties. Hall effect measurements on a variety of PEDOT samples show that the choice of doping...... that the chosen doping anion modifies the way PEDOT chains stack together. This link between structure and specific anion doping at high doping levels has ramifications for the fabrication of conducting polymer-based devices....

  9. Equilibrium and Thermodynamic Studies of Anionic Dyes Removal by an Anionic Clay-Layered Double Hydroxide

    International Nuclear Information System (INIS)

    Kantasamy, N.; Siti Mariam Sumari

    2016-01-01

    Adsorption isotherm describes the interaction of adsorbates with adsorbent in equilibrium. Equilibrium data was examined using Langmuir and Freundlich isotherm models. Thermodynamic studies were used to evaluate the thermodynamic parameters; heat of enthalpy change (ΔH degree), Gibbs free energy change (ΔG degree) and heat of entropy change (ΔSdegree) in order to gain information regarding the nature of adsorption (exothermic or endothermic). Four reactive dyes of anionic type, Acid Blue 29 (AB29), Reactive Black 5 (RB5), Reactive Orange 16 (RO16) and Reactive Red 120 (RR120) were used to obtain equilibrium isotherms at 25, 35, 45 and 55 degree Celsius. Based on Giles' classification, the isotherm produced were of L2-type, indicating strong dye affinity towards the adsorbent, and with weak competition with the solvent molecules for active adsorption sites. Equilibrium data fitted both Langmuir and Freundlich isotherm models with high correlation coefficient (R 2 > 0.91) indicating the possibility of both homogeneity and heterogeneous nature of adsorption. The negative values of ΔGdegree indicate the adsorption processes were spontaneous and feasible. The negative values of ΔHdegree lie between -20 to -75 kJ/ mol, suggesting these processes were exothermic and physical in nature. The negative values of ΔSdegree are indication of decreased disorder and randomness of spontaneous adsorption of reactive dyes on layered double hydroxide as adsorbent. (author)

  10. Retention of Anionic Species on Granite: Influence of Granite Composition - 12129

    Energy Technology Data Exchange (ETDEWEB)

    Videnska, Katerina [Institute of Chemical Technology, Prague (Czech Republic); Havlova, Vaclava [Nuclear Research Institute Rez, Rez, 25068 (Czech Republic)

    2012-07-01

    Technetium (Tc-99, T{sub 1/2} = 2.1.10{sup 5} yrs) and selenium (Se-79, T{sub 1/2} = 6.5.10{sup 4} yrs) belong among fission products, being produced by fission of nuclear fuel. Both elements can significantly contribute to risk due to their complicated chemistry, long life times, high mobility and prevailing anionic character. Therefore, knowledge of migration behaviour under different conditions can significantly improve input into performance and safety assessment models. Granite is considered as a potential host rock for deep geological disposal of radioactive waste in many countries. Granitic rocks consist usually of quartz, feldspar, plagioclase (main components), mica, chlorite, kaolinite (minor components). The main feature of the rock is advection governed transport in fractures, complemented with diffusion process from fracture towards undisturbed rock matrix. The presented work is focused on interaction of anionic species (TcO{sub 4}{sup -}, SeO{sub 4}{sup 2-}, SeO{sub 3}{sup 2-}) with granitic rock. Furthermore, the importance of mineral composition on sorption of anionic species was also studied. The batch sorption experiments were conducted on the crushed granite from Bohemian Massive. Five fractions with defined grain size were used for static batch method. Mineral composition of each granitic fraction was evaluated using X-ray diffraction. The results showed differences in composition of granitic fractions, even though originating from one homogenized material. Sorption experiments showed influence of granite composition on adsorption of both TcO4{sup -} and SeO3{sup 2-} on granitic rock. Generally, Se(IV) showed higher retention than Tc(VII). Se(VI) was not almost sorbed at all. Fe containing minerals are pronounced as a selective Se and Tc sorbent, being reduced on their surface. As micas in granite are usually enriched in Fe, increased sorption of anionic species onto mica enriched fractions can be explained by this reason. On the other hand

  11. Dietary cation anion difference: Impact on productive and ...

    African Journals Online (AJOL)

    Various nutritional tools have been used to improve the productive and reproductive performance of animals, among which difference between certain minerals, called dietary cation anion difference (DCAD) plays a pivotal role. Low or negative DCAD diets reduce blood pH and HCO3- and animal becomes acidotic.

  12. The effect of membrane diffusion potential change on anionic drugs ...

    African Journals Online (AJOL)

    The effect of membrane potential change on anionic drugs Indomethacin and barbitone induced human erythrocyte shape change and red cell uptake of drug has been studied using microscopy and spectrophotometry techniques respectively. The membrane potential was changed by reducing the extracellular chloride ...

  13. Core-modified octaphyrins: Syntheses and anion-binding properties

    Indian Academy of Sciences (India)

    Unknown

    proton of the inverted ring of selenophene from the biselenophene unit forms a secondary interaction. (non-electrostatic) with oxygen of the TFA. Apart from the oxygen, the fluorine of the triflate anion also forms secondary interaction with the proton of the methyl group of the mesityl ring. Tetraoxaoctaphyrin 9 also binds two ...

  14. Beneficiation of Nigerian Clay with Poly Anionic Cellulose-Regular ...

    African Journals Online (AJOL)

    ... concentrations and the effect of different concentration of Poly Anionic Cellulose-Regular (PAC-R) on the Emede clay was investigated. The experiment centred on the determination of its suitability for use in drilling mud formulation. Preliminary investigation suggests that Emede clay has a good potential for use in drilling ...

  15. Contribution of attendant anions on cadmium toxicity to soil enzymes.

    Science.gov (United States)

    Tian, Haixia; Kong, Long; Megharaj, Mallavarapu; He, Wenxiang

    2017-11-01

    Sorption and desorption are critical processes to control the mobility and biotoxicity of cadmium (Cd) in soils. It is known that attendant anion species of heavy metals could affect metal adsorption on soils and might further alter their biotoxicity. However, for Cd, the influence of attendant anions on its sorption in soils and subsequent toxicity on soil enzymes are still unknown. In this work, four Cd compounds with different salt anions (SO 4 2- , NO 3 - , Cl - , and Ac - ) were selected to investigate their impact of on the sorption, soil dehydrogenase activity (DHA) and alkaline phosphatase activity (ALP). Thus, a series of simulated Cd pollution batch experiments including measuring adsorption-desorption behavior of Cd on soils and soil enzyme activities were carried out. Results showed that CdSO 4 exhibited highest sorption capacity among the tested soils except in Hunan soil. The Cd sorption with NO 3 - displayed a similar behavior with Cl - on all tested soils. Compared with soil properties, all four kinds of anions on Cd sorption played a more significant role affecting Cd ecological toxicity to soil DHA and ALP. Cd in acetate or nitrate form appears more sensitive towards DHA than sulphate and chloride, while the later pair is more toxic towards ALP than the former. These results have important implications for evaluation of Cd contamination using soil enzyme as bioindicator. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. The anionic biosurfactant rhamnolipid does not denature industrial enzymes

    Directory of Open Access Journals (Sweden)

    Jens Kvist Madsen

    2015-04-01

    Full Text Available Biosurfactants (BS are surface-active molecules produced by microorganisms. Their combination of useful properties and sustainable production make them promising industrial alternatives to petrochemical and oleochemical surfactants. Here we compare the impact of the anionic BS rhamnolipid (RL and the conventional/synthetic anionic surfactant sodium dodecyl sulfate (SDS on the structure and stability of three different commercially used enzymes, namely the cellulase Carezyme® (CZ, the phospholipase Lecitase Ultra® (LT and the α-amylase Stainzyme® (SZ. Our data reveal a fundamental difference in their mode of interaction. SDS shows great diversity of interaction towards the different enzymes. It efficiently unfolds both LT and CZ, but LT is unfolded by SDS through formation of SDS clusters on the protein well below the cmc, while CZ is only unfolded by bulk micelles and on average binds significantly less SDS than LT. SDS binds with even lower stoichiometry to SZ and leads to an increase in thermal stability. In contrast, RL does not affect the tertiary or secondary structure of any enzyme at room temperature, has little impact on thermal stability and only binds detectably (but at low stoichiometries to SZ. Furthermore all enzymes maintain activity at both monomeric and micellar concentrations of RL. We conclude that RL, despite its anionic charge, is a surfactant that does not compromise the structural integrity of industrially relevant proteins. This makes RL a promising alternative to current synthetic anionic surfactants in a wide range of commercial applications.

  17. A carbohydrate-anion recognition system in aprotic solvents.

    Science.gov (United States)

    Ren, Bo; Dong, Hai; Ramström, Olof

    2014-05-01

    A carbohydrate-anion recognition system in nonpolar solvents is reported, in which complexes form at the B-faces of β-D-pyranosides with H1-, H3-, and H5-cis patterns similar to carbohydrate-π interactions. The complexation effect was evaluated for a range of carbohydrate structures; it resulted in either 1:1 carbohydrate-anion complexes, or 1:2 complex formation depending on the protection pattern of the carbohydrate. The interaction was also evaluated with different anions and solvents. In both cases it resulted in significant binding differences. The results indicate that complexation originates from van der Waals interactions or weak CH⋅⋅⋅A(-) hydrogen bonds between the binding partners and is related to electron-withdrawing groups of the carbohydrates as well as increased hydrogen-bond-accepting capability of the anions. © 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

  18. Electronic spectra of anions intercalated in layered double hydroxides

    Indian Academy of Sciences (India)

    Transition metal complexes intercalated in layered double hydroxides have a different electronic structure as compared to their free state owing to their confinement within the interlayer gallery. UV–Vis absorptions of the intercalated complex anions show a significant shift as compared to their free state. The ligand to metal ...

  19. Measurement of carbon disulfide anion diffusion in a TPC

    International Nuclear Information System (INIS)

    Ohnuki, Tohru; Snowden-Ifft, D.P.Daniel P.; Martoff, C.J.C. Jeff

    2001-01-01

    A Negative Ion Time Projection Chamber was used to measure the field dependence of lateral and longitudinal diffusion for CS 2 anions drifting in mixtures of CS 2 and Ar at 40 Torr. Ion drift velocities and limits on the capture distance for electrons as a function of field and gas mixture are also reported

  20. Changes in plasma osmolality and anion gap: potential predictors of ...

    African Journals Online (AJOL)

    These changes may be related to mortality in patients on haemodialysis. Objective: To determine the relationship of mortality to plasma osmolality and anion gap inpatients on haemodialysis. Methods: Fifty consecutive dialysis naive stable stage 5 chronic kidney disease subjects aged between 18 and 70 years, attending a ...

  1. The Determination of Anionic Surfactants in Natural and Waste Waters.

    Science.gov (United States)

    Crisp, P. T.; And Others

    1983-01-01

    Background information, procedures, and results of an experiment suitable for measuring subpart per million concentrations of anionic surfactants in natural waters and waste effluents are provided. The experiment required only a spectrophotometer or filter photometer and has been successfully performed by students in an undergraduate environmental…

  2. Anionic construction of the SLq,s(2) algebra

    International Nuclear Information System (INIS)

    Matheus-Valle, J.L.; Monteiro, M.R.

    1993-01-01

    Considering anionic oscillators in a two-dimensional lattice, the quantum semi-group sl (q,s ) (2) is realized by means of a generalized Schwinger construction. It is found that the parameter q of the algebra is connected to the statistical parameter, whereas the s parameter is related to a s-deformed oscillator introduced at each point of the lattice. (author)

  3. Anion binding in covalent and self-assembled molecular capsules.

    Science.gov (United States)

    Ballester, Pablo

    2010-10-01

    This critical review describes selected examples extracted from the extensive literature generated during the past 42 years on the topic of anion binding in molecular capsules. The goal of including anions in molecular capsules emerges from the idea of incorporating the traits exhibited by biological receptors into synthetic ones. At the outset of this research area the capsules were unimolecular. The scaffold of the receptor was designed to covalently link a series of functional groups that could converge into a cavity and to avoid its collapse. The initial examples involved the encapsulation of one monoatomic spherical anion. With time, the cavity size of the receptor was increased and encapsulation of polyatomic anions and co-encapsulation became a reality. Synthetic economy fueled the use of aggregates of self-complementary molecules rather than one large molecule as capsules. The main purpose of this review is to give a general overview of the topic which might be of interest to supramolecular or non supramolecular chemists alike (149 references).

  4. Efficiency of superoxide anions in the inactivation of selected dehydrogenases

    International Nuclear Information System (INIS)

    Rodacka, Aleksandra; Serafin, Eligiusz; Puchala, Mieczyslaw

    2010-01-01

    The most ubiquitous of the primary reactive oxygen species, formed in all aerobes, is the superoxide free radical. It is believed that the superoxide anion radical shows low reactivity and in oxidative stress it is regarded mainly as an initiator of more reactive species such as · OH and ONOO - . In this paper, the effectiveness of inactivation of selected enzymes by radiation-generated superoxide radicals in comparison with the effectiveness of the other products of water radiolysis is examined. We investigate three enzymes: glyceraldehyde-3-phosphate dehydrogenase (GAPDH), alcohol dehydrogenase (ADH) and lactate dehydrogenase (LDH). We show that the direct contribution of the superoxide anion radical to GAPDH and ADH inactivation is significant. The effectiveness of the superoxide anion in the inactivation of GAPDH and ADG was only 2.4 and 2.8 times smaller, respectively, in comparison with hydroxyl radical. LDH was practically not inactivated by the superoxide anion. Despite the fact that the studied dehydrogenases belong to the same class of enzymes (oxidoreductases), all have a similar molecular weight and are tetramers, their susceptibility to free-radical damage varies. The differences in the radiosensitivity of the enzymes are not determined by the basic structural parameters analyzed. A significant role in inactivation susceptibility is played by the type of amino acid residues and their localization within enzyme molecules.

  5. Efficiency of superoxide anions in the inactivation of selected dehydrogenases

    Energy Technology Data Exchange (ETDEWEB)

    Rodacka, Aleksandra, E-mail: olakow@biol.uni.lodz.p [Department of Molecular Biophysics, University of Lodz, Banacha 12/16, 90-237 Lodz (Poland); Serafin, Eligiusz, E-mail: serafin@biol.uni.lodz.p [Laboratory of Computer and Analytical Techniques, University of Lodz, Banacha 12/16, 90-237 Lodz (Poland); Puchala, Mieczyslaw, E-mail: puchala@biol.uni.lodz.p [Department of Molecular Biophysics, University of Lodz, Banacha 12/16, 90-237 Lodz (Poland)

    2010-09-15

    The most ubiquitous of the primary reactive oxygen species, formed in all aerobes, is the superoxide free radical. It is believed that the superoxide anion radical shows low reactivity and in oxidative stress it is regarded mainly as an initiator of more reactive species such as {sup {center_dot}}OH and ONOO{sup -}. In this paper, the effectiveness of inactivation of selected enzymes by radiation-generated superoxide radicals in comparison with the effectiveness of the other products of water radiolysis is examined. We investigate three enzymes: glyceraldehyde-3-phosphate dehydrogenase (GAPDH), alcohol dehydrogenase (ADH) and lactate dehydrogenase (LDH). We show that the direct contribution of the superoxide anion radical to GAPDH and ADH inactivation is significant. The effectiveness of the superoxide anion in the inactivation of GAPDH and ADG was only 2.4 and 2.8 times smaller, respectively, in comparison with hydroxyl radical. LDH was practically not inactivated by the superoxide anion. Despite the fact that the studied dehydrogenases belong to the same class of enzymes (oxidoreductases), all have a similar molecular weight and are tetramers, their susceptibility to free-radical damage varies. The differences in the radiosensitivity of the enzymes are not determined by the basic structural parameters analyzed. A significant role in inactivation susceptibility is played by the type of amino acid residues and their localization within enzyme molecules.

  6. based anion exchange membrane for alkaline polymer electrolyte

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Hydroxyl ion (OH–) conducting anion exchange membranes based on modified poly (phenylene oxide) are fabricated for their application in alkaline polymer electrolyte fuel cells (APEFCs). In the present study, chloromethylation of poly(phenylene oxide) (PPO) is performed by aryl substitution rather than benzyl.

  7. Spectral modulation through controlling anions in nanocaged phosphors

    NARCIS (Netherlands)

    Bian, H.; Liu, Y.; Yan, D.; Zhu, H.; Liu, C.; Xu, C.S.; Liu, Y.; Zhang, H.; Wang, X.

    2013-01-01

    A new approach has been proposed and validated to modulate the emission spectra of europium-doped 12CaO center dot 7Al(2)O(3) phosphors by tuning the nonradiative and radiative transition rates, realized by controlling the sort and amount of the encaged anions. A single wavelength at 255 nm can

  8. Adsorption and intercalation of anionic surfactants onto layered ...

    Indian Academy of Sciences (India)

    Layered double hydroxides (LDH) with brucite like structure was modified with various anionic surfactants containing sulfonate, carboxyl, phosphonate and sulfate end group through ion-exchange method. XRD reports indicated that the sulfonate group containing surfactants led to an adsorption process whereas the sulfate ...

  9. Adsorption and intercalation of anionic surfactants onto layered ...

    Indian Academy of Sciences (India)

    Unknown

    MS received 12 October 2004; revised 10 January 2005. Abstract. Layered ... son 2004). Bifunctional short chain anionic surfactant such as tartrate and succinate intercalated Zn/Cr LDH was prepared by Prevot and co-workers (1998). Terephthalate ..... He L, Yin S and Sato T 2003 Solid State Chem. 77 51. Isupov V P and ...

  10. Adsorption and intercalation of anionic surfactants onto layered ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Layered double hydroxides (LDH) with brucite like structure was modified with various anionic surfactants containing sulfonate, carboxyl, phosphonate and sulfate end group through ion-exchange method. XRD reports indicated that the sulfonate group containing surfactants led to an adsorption process whereas.

  11. Functional Block Copolymers via Anionic Polymerization for Electroactive Membranes

    OpenAIRE

    Schultz, Alison

    2013-01-01

           Ion-containing block copolymers blend ionic liquid properties with well-defined polymer architectures. This provides conductive materials with robust mechanical stability, efficient processability, and tunable macromolecular design. Conventional free radical polymerization and anion exchange achieved copolymers containing n-butyl acrylate and phosphonium ionic liquids. These compositions incorporated vinylbenzyl triphenyl phosphonium and vinylbenzyl tricyclohexyl phosphonium cations be...

  12. Total synthesis of ascididemin via anionic cascade ring closure

    DEFF Research Database (Denmark)

    Petersen, Ida Nymann; Crestey, François; Kristensen, Jesper Langgaard

    2012-01-01

    A new and convergent synthesis of ascididemin is presented. Using an anionic cascade ring closure as the key step, this natural product is obtained in 45% overall yield in just 6 steps starting from 2'-fluoroacetophenone. This new approach was extended to the synthesis of a new isomer...

  13. Rejuvenation processes applied to 'poisoned' anion exchangers in uranium processing

    International Nuclear Information System (INIS)

    Gilmore, A.J.

    1979-11-01

    The removal of 'poisons' from anion exchangers in uranium processing of Canadian radioactive ores is commonly called rejuvenation or regeneration. The cost of the ion exchange recovery of uranium is adversely affected by a decrease in the capacity and efficiency of the anion exchangers, due to their being 'poisoned' by silica, elemental sulphur, molybdenum and tetrathionates. These 'poisons' have a high affinity for the anion exchangers, are adsorbed in preference to the uranyl complex, and do not desorb with the reagents used normally in the uranyl desorption phase. The frequency of rejuvenation and the reagents required for rejuvenation are determined by the severity of the 'poisoning' accumulated by the exchanger in contact with the uranium leach liquor. Caustic soda (NaOH) at approximately equal to 18 cents/lb is commonly used to remove uranium anion exchangers of tetrathionate ((S 4 0 6 )/-/-) 'poisons'. A potential saving in operating cost would be of consequence if other reagents, e.g. sodium carbonate (Na 2 CO 3 ) at approximately equal to 3.6 cents/lb or calcium hydroxide (Ca(OH) 2 ) at approximately equal to 1.9 cents/lb, were effective in removing (S 4 0 6 )/-/-) from a 'poisoned' exchanger. A rejuvenation process for a test program was adopted after a perusal of the literature

  14. Anion complexation by calix[4]arene–TTF conjugates

    Czech Academy of Sciences Publication Activity Database

    Flídrová, K.; Tkadlecová, M.; Lang, Kamil; Lhoták, P.

    2012-01-01

    Roč. 92, č. 1 (2012), s. 668-673 ISSN 0143-7208 R&D Projects: GA ČR GA203/09/0691 Institutional research plan: CEZ:AV0Z40320502 Keywords : calix[4]arene * tetrathiafulvalene * anion recognition * receptor * NMR titration * UV/vis spectroscopy Subject RIV: CA - Inorganic Chemistry Impact factor: 3.532, year: 2012

  15. Novel Biscalix[4]arene-based Anion Receptors

    Czech Academy of Sciences Publication Activity Database

    Šťastný, V.; Lhoták, P.; Michlová, V.; Stibor, I.; Sýkora, Jan

    2002-01-01

    Roč. 58, č. 36 (2002), s. 7207-7211 ISSN 0040-4020 R&D Projects: GA ČR GA104/00/1722; GA ČR GA203/00/1011 Keywords : calixarenes * anion receptors * NMR titration Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.420, year: 2002

  16. Anion-based approaches to tunable functionality in oxide heterostructures

    Science.gov (United States)

    May, Steven

    2014-03-01

    The ability to control the position and composition of the anion site is emerging as a promising route to tune properties in epitaxial perovskites. This talk will focus on recent and ongoing efforts aimed at developing anion-based approaches to tailor electronic and magnetic properties in oxide films. First, I will discuss how the position of the oxygen anions can be tailored to stabilize non-bulk-like bond angles and lengths, thereby altering electronic bandwidth. Recent work on La2/3Sr1/3MnO3 will be presented in which ultrathin films under the same strain state exhibit dramatically different electronic and magnetic properties when grown on substrates with different symmetries. In the second half of the talk, I will describe efforts focused on altering the composition of the anion site. In La1/3Sr2/3FeO3-δ films, a reversible change in oxygen content leads to dramatic changes in electrical, optical, and structural properties. Finally, the synthesis of oxyfluoride ferrite and nickelate perovskite films via topotactic reactions carried out following thin film deposition will be described. This work is supported by the Office of Naval Research (N00014-11-1-0664) and the U. S. Army Research Office (W911NF-12-1-0132).

  17. On the Adsorption of Some Anionic Collectors on Fluoride Minerals

    DEFF Research Database (Denmark)

    Sørensen, Emil

    1973-01-01

    Test flotations have been carried out in a small apparatus under standardized conditions in order to determine the dependence of the flotation yield on the reagent concentration for certain minerals and anionic collectors. The results suggest that a special adsorption mechanism is operating...

  18. Anion effects on the cyclobis(paraquat-p-phenylene) host

    DEFF Research Database (Denmark)

    Andersen, Sissel Stenbæk; Jensen, Morten; Sørensen, Anne

    2012-01-01

    Binding studies between the electron accepting host cyclobis(paraquat-p-phenylene) and a series of electron donors in the presence of differently sized counteranions reveal that both the nature and the concentration of the anion have a large impact on the association strength of the resulting host...

  19. Capturing and concentrating adenovirus using magnetic anionic nanobeads

    Science.gov (United States)

    Sakudo, Akikazu; Baba, Koichi; Ikuta, Kazuyoshi

    2016-01-01

    We recently demonstrated how various enveloped viruses can be efficiently concentrated using magnetic beads coated with an anionic polymer, poly(methyl vinyl ether-maleic anhydrate). However, the exact mechanism of interaction between the virus particles and anionic beads remains unclear. To further investigate whether these magnetic anionic beads specifically bind to the viral envelope, we examined their potential interaction with a nonenveloped virus (adenovirus). The beads were incubated with either adenovirus-infected cell culture medium or nasal aspirates from adenovirus-infected individuals and then separated from the supernatant by applying a magnetic field. After thoroughly washing the beads, adsorption of adenovirus was confirmed by a variety of techniques, including immunochromatography, polymerase chain reaction, Western blotting, and cell culture infection assays. These detection methods positively identified the hexon and penton capsid proteins of adenovirus along with the viral genome on the magnetic beads. Furthermore, various types of adenovirus including Types 5, 6, 11, 19, and 41 were captured using the magnetic bead procedure. Our bead capture method was also found to increase the sensitivity of viral detection. Adenovirus below the detectable limit for immunochromatography was efficiently concentrated using the magnetic bead procedure, allowing the virus to be successfully detected using this methodology. Moreover, these findings clearly demonstrate that a viral envelope is not required for binding to the anionic magnetic beads. Taken together, our results show that this capture procedure increases the sensitivity of detection of adenovirus and would, therefore, be a valuable tool for analyzing both clinical and experimental samples. PMID:27274228

  20. Evaluation of Some Anionic Exchange Resins as Potential Tablet ...

    African Journals Online (AJOL)

    Starches, clays, gums and hydrophilic cellulosic polymers have historically ... expand such interesting applications to anionic exchange resins ..... Edition, Revised and. Expanded. New York: Marcel Dekker; 1989; pp 75-. 130. 4. Goyanes A, Souto C, Martíínez-Pacheco R. A comparison of chitosan-silica and sodium starch.

  1. Intermolecular proton transfer in anionic complexes of uracil with alcohols

    International Nuclear Information System (INIS)

    Haranczyk, Maciej; Rak, Janusz; Gutowski, Maciej S.; Radisic, Dunja; Stokes, Sarah T.; Bowen, Kit H.

    2005-01-01

    A series of eighteen alcohols (ROH) has been designed with an enthalpy of deprotonation (H DP ) in a range of 13.8-16.3 eV. The effects of excess electron attachment to the binary alcohol-uracil (ROH...U) complexes have been studied at the density functional level with a B3LYP exchange-correlation functional and at the second order Moeller-Plesset perturbation theory level. The photoelectron spectra of anionic complexes of uracil with three alcohols (ethanol, 2,2,3,3,3-pentafluoroethanol and 1,1,1,3,3,3-hexafluoro-2-propanol) have been measured with 2.54 eV photons. For ROHs with deprotonation enthalpies larger than 14.8 eV only the ROH...U - minimum exists on the potential energy surface of the anionic complex. For alcohols with deprotonation enthalpies in a range of 14.3-14.8 eV two minima might exist on the anionic potential energy surface, which correspond to the RO - ...HU . and ROH...U - structures. For ROHs with deprotonation enthalpies smaller than 14.3 eV, the excess electron attachment to the ROH...U complex always induces a barrier-free proton transfer from the hydroxyl group of ROH to the O8 atom of U, with the product being RO - ...HU . . A driving force for the intermolecular proton transfer is to stabilize the excess negative charge localized on a orbital of uracil. Therefore, these complexes with proton transferred to the anionic uracil are characterized by larger values of electron vertical detachment energy (VDE). The values of VDE for anionic complexes span a range from 1.0 to 2.3 eV and roughly correlate with the acidity of alcohols. However, there is a gap of ∼0.5 eV in the values of VDE, which separates the two families, ROH...U - and RO - ...HU . , of anionic complexes. The energy of stabilization for the anionic complexes spans a range from 0.6 to 1.7 eV and roughly correlates with the acidity of alcohols. The measured photoelectron spectra are in good agreement with the theoretical predictions

  2. Role of Vitamin D in Maintaining Renal Epithelial Barrier Function in Uremic Conditions

    Directory of Open Access Journals (Sweden)

    Milos Mihajlovic

    2017-11-01

    Full Text Available As current kidney replacement therapies are not efficient enough for end-stage renal disease (ESRD treatment, a bioartificial kidney (BAK device, based on conditionally immortalized human proximal tubule epithelial cells (ciPTEC, could represent an attractive solution. The active transport activity of such a system was recently demonstrated. In addition, endocrine functions of the cells, such as vitamin D activation, are relevant. The organic anion transporter 1 (OAT-1 overexpressing ciPTEC line presented 1α-hydroxylase (CYP27B1, 24-hydroxylase (CYP24A1 and vitamin D receptor (VDR, responsible for vitamin D activation, degradation and function, respectively. The ability to produce and secrete 1α,25-dihydroxy-vitamin D3, was shown after incubation with the precursor, 25-hydroxy-vitamin D3. The beneficial effect of vitamin D on cell function and behavior in uremic conditions was studied in the presence of an anionic uremic toxins mixture. Vitamin D could restore cell viability, and inflammatory and oxidative status, as shown by cell metabolic activity, interleukin-6 (IL-6 levels and reactive oxygen species (ROS production, respectively. Finally, vitamin D restored transepithelial barrier function, as evidenced by decreased inulin-FITC leakage in biofunctionalized hollow fiber membranes (HFM carrying ciPTEC-OAT1. In conclusion, the protective effects of vitamin D in uremic conditions and proven ciPTEC-OAT1 endocrine function encourage the use of these cells for BAK application.

  3. From isolated 1H-pyrazole cryptand anion receptors to hybrid inorganic–organic 1D helical polymeric anion receptors

    OpenAIRE

    Pitarch-Jarque, Javier; Belda, Raquel; García-España, Laura; Llinares, José M.; Pan, Fangfang; Rissanen, Kari; Navarro, Pilar; García-España, Enrique

    2015-01-01

    We report on a novel 1-D helical coordination polymer formed by protonated polyamine 1H-pyrazole cryptands interconnected by Cu2+ metal ions able to encapsulate anionic species behaving as a multianion receptor. Switching from the monomeric to the polymeric receptor is activated by metal ions and pH.

  4. Reducing nitrogen crossover in microbial reverse-electrodialysis cells by using adjacent anion exchange membranes and anion exchange resin

    KAUST Repository

    Wallack, Maxwell J.

    2015-01-01

    Microbial reverse electrodialysis cells (MRECs) combine power generation from salinity gradient energy using reverse electrodialysis (RED), with power generation from organic matter using a microbial fuel cell. Waste heat can be used to distill ammonium bicarbonate into high (HC) and low salt concentration (LC) solutions for use in the RED stack, but nitrogen crossover into the anode chamber must be minimized to avoid ammonia loses, and foster a healthy microbial community. To reduce nitrogen crossover, an additional low concentration (LC) chamber was inserted before the anode using an additional anion exchange membrane (AEM) next to another AEM, and filled with different amounts of anion or cation ion exchange resins. Addition of the extra AEM increased the ohmic resistance of the test RED stack from 103 Ω cm2 (1 AEM) to 295 Ω cm2 (2 AEMs). However, the use of the anion exchange resin decreased the solution resistance of the LC chamber by 74% (637 Ω cm2, no resin; 166 Ω cm2 with resin). Nitrogen crossover into the anode chamber was reduced by up to 97% using 50% of the chamber filled with an anion exchange resin compared to the control (no additional chamber). The added resistance contributed by the use of the additional LC chamber could be compensated for by using additional LC and HC membrane pairs in the RED stack.

  5. Effect of cationic and anionic surfactants on the sorption and desorption of perfluorooctane sulfonate (PFOS) on natural sediments

    Energy Technology Data Exchange (ETDEWEB)

    Pan Gang [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China)], E-mail: gpan@rcees.ac.cn; Jia Chengxia [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China); Zhao Dongye [Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States); You Chun; Chen Hao; Jiang Guibin [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China)

    2009-01-15

    Sorption and desorption of PFOS at water-sediment interfaces were investigated in the presence of a cationic surfactant, cetyltrimethylammonium bromide (CTAB), and an anionic surfactant, sodium dodecylbenzene sulfonate (SDBS). CTAB remarkably enhanced the sorption of PFOS on the sediment. In contrast, the influence of SDBS to the sorption of PFOS was concentration dependent. Two contrasting factors were responsible for the phenomenon. One was the sorption of the surfactant itself to the sediment, which enhanced the sorption of PFOS. The other was the increase in solubility of PFOS caused by the adding of surfactants, which decreased the sorption of PFOS. SDBS had a much lower sorption capacity, but rather strong ability to increase the solubility of PFOS. High levels of SDBS remarkably reduced the sorption of PFOS on the sediment. These results imply that cationic and anionic surfactants may have contrast impacts on the distribution and transport of PFOS in the environment. - Cationic surfactant CTAB can immobilize PFOS but anionic surfactant SDBS mobilize PFOS onto/from the sediments.

  6. Study of electron transition energies between anions and cations in spinel ferrites using differential UV–vis absorption spectra

    Energy Technology Data Exchange (ETDEWEB)

    Xue, L.C.; Wu, L.Q. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); Li, S.Q. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); School of Sciences, Hebei University of Science and Technology, Shijiazhuang City 050018 (China); Li, Z.Z. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); Tang, G.D., E-mail: tanggd@mail.hebtu.edu.cn [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); Qi, W.H.; Ge, X.S.; Ding, L.L. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China)

    2016-07-01

    It is very important to determine electron transition energies (E{sub tr}) between anions and different cations in order to understand the electrical transport and magnetic properties of a material. Many authors have analyzed UV–vis absorption spectra using the curve (αhν){sup 2} vs E, where α is the absorption coefficient and E(=hν) is the photon energy. Such an approach can give only two band gap energies for spinel ferrites. In this paper, using differential UV–vis absorption spectra, dα/dE vs E, we have obtained electron transition energies (E{sub tr}) between the anions and cations, Fe{sup 2+} and Fe{sup 3+} at the (A) and [B] sites and Ni{sup 2+} at the [B] sites for the (A)[B]{sub 2}O{sub 4} spinel ferrite samples Co{sub x}Ni{sub 0.7−x}Fe{sub 2.3}O{sub 4} (0.0≤x≤0.3), Cr{sub x}Ni{sub 0.7}Fe{sub 2.3−x}O{sub 4} (0.0≤x≤0.3) and Fe{sub 3}O{sub 4}. We suggest that the differential UV–vis absorption spectra should be accepted as a general analysis method for determining electron transition energies between anions and cations.

  7. Influence of anionic monomer content on the biodegradation and toxicity of polyvinyl-urethane carbonate-ceramic interpenetrating phase composites.

    Science.gov (United States)

    Yang, Liu; Hong, Jason; Wang, Jian; Pilliar, Robert M; Santerre, J Paul

    2005-10-01

    The objective of this study was to characterize a series of anionic biodegradable polymer resins for their compatibility in a biological environment, comparing them with respect to the influence of ionic function on enzyme catalyzed biodegradation when the polymers were incorporated into a porous calcium polyphosphate (CPP) 3-D structure to form an interpenetrating phase composite (IPC). The swelling behavior of the polymers was investigated by immersing the cured polymer resins in growth media at 37 degrees C. In vitro cytotoxicity of the polymer resins was assessed using a HeLa cell line. Cell viability increased when the amount of low molecular weight monomer was minimized. Despite observing that the addition of carboxylic acid groups into the polymer resin chains contributed to an improvement of the chemical bonding between the polymer and the CPP, the addition of high ionic content into the resin led to the greatest loss of bending strength for the samples incubated in phosphate buffer and cholesterol esterase enzyme solutions, when compared to their as made state. The increased degradation for the higher ionic component materials and their loss of physical strength was attributed to enhanced hydrolysis within the materials and by water transport deep within the composites, via the anionic components of the resin. The findings indicated that the introduction of anionic content must be optimized to promote increased mechanical performance for the CPP, balancing the features of polymer CPP bonding versus polymer swelling and cytotoxicity.

  8. Contribution of various metabolites to the "unmeasured" anions in critically ill patients with metabolic acidosis.

    NARCIS (Netherlands)

    Moviat, M.; Terpstra, A.M.; Ruitenbeek, W.; Kluijtmans, L.A.J.; Pickkers, P.; Hoeven, J.G. van der

    2008-01-01

    OBJECTIVE: The physicochemical approach, described by Stewart to investigate the acid-base balance, includes the strong ion gap (SIG), a quantitative measure of "unmeasured" anions, which strongly correlates to the corrected anion gap. The chemical nature of these anions is for the most part

  9. Using remote substituents to control solution structure and anion binding in lanthanide complexes

    DEFF Research Database (Denmark)

    Tropiano, Manuel; Blackburn, Octavia A.; Tilney, James A.

    2013-01-01

    A study of the anion-binding properties of three structurally related lanthanide complexes, which all contain chemically identical anion-binding motifs, has revealed dramatic differences in their anion affinity. These arise as a consequence of changes in the substitution pattern on the periphery ...

  10. Use of weak ion association in the separation of inorganic anions by ...

    African Journals Online (AJOL)

    In this work weak ion association was used to effect selectivity and detection of inorganic anions with environmental or health significance by capillary electropheresis, CE. Tetrabutylammonium ion was used as a pairing anion to separate mixtures containing closely or co-migrating inorganic anions at pHs 3.8 and pH 7.

  11. Synthesis and anion exchange reactions of a layered copper-zinc ...

    Indian Academy of Sciences (India)

    Acetate ions can be exchanged with simple inorganic anions such as chloride and nitrate, and organic anions such as benzoate and large surfactant anions such as dodecyl sulphate. Structures of these hydroxysalts are derived from that of Cu2(OH)3NO3 ⋅ H2O with some of the Cu2+ ions being replaced by Zn2+.

  12. Synthesis and anion exchange reactions of a layered copper–zinc ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. A mixed-metal hydroxysalt of formula Cu1⋅6Zn0⋅4(OH)3(OAc)⋅H2O has been synthesized by an acetate hydrolysis route. Acetate ions can be exchanged with simple inorganic anions such as chloride and nitrate, and organic anions such as benzoate and large surfactant anions such as dodecyl sulphate. Struc-.

  13. Update on value of the anion gap in clinical diagnosis and laboratory evaluation.

    Science.gov (United States)

    Lolekha, P H; Vanavanan, S; Lolekha, S

    2001-05-01

    Anion gap (AG) is a calculated value commonly used in clinical practice. It approximates the difference between the concentration of unmeasured anions (UA) and unmeasured cations (UC) in serum. At present, the reference range of anion gap has been lowered from 8-16 to 3-11 mmol/l because of the changes in technique for measuring electrolyte. However, clinicians and textbooks still refer and use the old reference value of 8-16 mmol/l. This may lead to misinterpretation of the value of anion gap. Our study updated the value of anion gap in clinical diagnosis and laboratory evaluation. Criteria for using anion gap were also suggested. We analyzed serum electrolyte using the Beckman Synchron CX5. The anion gap was calculated from the formula: [Na(+)-(Cl(-)+HCO(3)(-))]. We estimated the reference range using the non-parametric percentile estimation method. The reference range of anion gap obtained from 124 healthy volunteers was 5-12 mmol/l, which was low and confirmed the reports from other studies (3-11 mmol/l) using ion-selective electrode. From the retrospective study on the 6868 sets of serum electrolyte among hospitalized patients, we found the incidences of normal, increased, and decreased anion gaps were 59.5%, 37.6%, and 2.9%, respectively. The mean and central 90% range of increased anion gap were 16 and 13-20 mmol/l, which was lower than those reported in previous study (25 and 19-28 mmol/l). Anion gap exceeding 24 mmol/l was rare. The mean and central 90% range of decreased anion gap were 3 and 2-4 mmol/l, which were lower than those reported in previous study (6 and 3-8 mmol/l). The value of less than 2 mmol/l was rare. The most common causes of increased anion gap (hypertensive disease, chronic renal failure, malignant neoplasms, diabetes mellitus and heart diseases) and decreased anion gap (liver cirrhosis and nephrotic syndrome) in this study were similar to those in previous studies. We found two cases of IgG multiple myeloma with anion gap of 2 mmol

  14. Layered rare-earth hydroxide nanocones with facile host composition modification and anion-exchange feature: topotactic transformation into oxide nanocones for upconversion.

    Science.gov (United States)

    Zhong, Yishun; Chen, Gen; Liu, Xiaohe; Zhang, Dan; Zhang, Ning; Li, Junhui; Liang, Shuquan; Ma, Renzhi; Qiu, Guanzhou

    2017-06-22

    Conical structures with hollow interiors, namely, nanocones (NCs), may exhibit better carrier transport properties than nanorods or nanotubes, which make them promising candidates for potential applications in optical/display devices, electronics and optoelectronics. Generally, conical structures belong to a metastable state between lamellar and tubular forms due to the extreme curvature causing the increase of internal strain energy. Therefore, it is very difficult to prepare NCs in high yield and purity under mild conditions. Here we firstly demonstrate a general strategy for the synthesis of layered rare-earth hydroxide (LRH) NCs intercalating dodecyl sulfate anions (C 12 H 25 SO 4 - , DS - ) using hexamethylenetetramine (C 6 H 12 N 4 , HMT) hydrolysis. The rare-earth cations (RE 3+ ) in the host layer can be conveniently modified and/or doped, resulting in a large family of monometallic (Y, Tb, Er), bi- (Y-Tb, Y-Er) and even tri-metallic (Y-Yb-Er) LRH NCs with adjustable ratios. Moreover, the DS - -intercalated LRH NCs can be readily modified with various inorganic or organic anions (e.g., NO 3 - , Cl - , and CH 3 COO - , etc.) through a conventional anion-exchange procedure, and the original conical morphology can be perfectly maintained. The anion-exchanged product, for example, NO 3 - -intercalated NCs, can be more easily and topotactically transformed into oxide NCs than the original DS - -intercalated form, exempt from the formation of rare-earth oxysulfates induced by the combustion of interlayer DS anions. Taking advantage of this protocol, tri-metallic (Y-Yb-Er) LRH NCs were anion-exchanged into the NO 3 - -intercalated form and subsequently calcined into Y 2 O 3 :Yb,Er oxide NCs, which showed efficient upconversion photoluminescence properties. The current strategy may become a general method for the designed synthesis of other related hydroxide and oxide NCs for a wide range of potential applications.

  15. The immobilization of anion exchange resins in polymer modified cements

    International Nuclear Information System (INIS)

    Dyer, A.; Morgan, P.D.

    1991-09-01

    Organic anion exchange resins, loaded with 99-Tc as the pertechnate ion, were incorporated into polymer modified cements (Flexocrete Ltd, Preston). BFS/OPC (9:1 mix) also was modified by three polymers from the same source (styrene acrylic (2) styrene butadiene) and loaded with anion exchanger containing the pertechnate. Composites were tested for initial compressive strengths, under water and radiation stability and leach rate. IAEA standard leach testing was with simulated sea and ground waters. Ground water leaching also was carried out on composites subjected to 1.10 9 rads (γ). Leach testing correlated well with compressive strength. Modified composites performed better than the BFS/OPC mix under all conditions studied and were able to encapsulate higher resin loadings. (author)

  16. Facile synthesis of hollow silica nanospheres employing anionic PMANa templates

    Science.gov (United States)

    Shi, Yan; Takai, Chika; Shirai, Takashi; Fuji, Masayoshi

    2015-05-01

    This article presents a facile and green route to the synthesis of hollow silica particles by means of anionic particles of poly(sodium methacrylate) (PMANa) as templates. This method was composed of the following three steps: formation of PMANa particles in ethanol by nanoprecipitation, the deposition of silica shell on the polymer cores through sol-gel process of tetraethylorthosilicate under catalysis of ammonia, and removal of the polymer templates by washing with water. The templates' size can be controlled in the range of about 70-140 nm by altering the ratio of ethanol to water, the polymer solution concentration, the ethanol amount in polymer solution, and the silica shell thickness can be adjusted between 15 and 30 nm by varying the ratio of silica precursor to the polymer cores. A tentative interpretation about the silica-coating process on the anionic PMANa particles was also proposed according to the experimental results.

  17. Anionic lipids and the maintenance of membrane electrostatics in eukaryotes.

    Science.gov (United States)

    Platre, Matthieu Pierre; Jaillais, Yvon

    2017-02-01

    A wide range of signaling processes occurs at the cell surface through the reversible association of proteins from the cytosol to the plasma membrane. Some low abundant lipids are enriched at the membrane of specific compartments and thereby contribute to the identity of cell organelles by acting as biochemical landmarks. Lipids also influence membrane biophysical properties, which emerge as an important feature in specifying cellular territories. Such parameters are crucial for signal transduction and include lipid packing, membrane curvature and electrostatics. In particular, membrane electrostatics specifies the identity of the plasma membrane inner leaflet. Membrane surface charges are carried by anionic phospholipids, however the exact nature of the lipid(s) that powers the plasma membrane electrostatic field varies among eukaryotes and has been hotly debated during the last decade. Herein, we discuss the role of anionic lipids in setting up plasma membrane electrostatics and we compare similarities and differences that were found in different eukaryotic cells.

  18. Synthesis of Randomly Substituted Anionic Cyclodextrins in Ball Milling.

    Science.gov (United States)

    Jicsinszky, László; Caporaso, Marina; Calcio Gaudino, Emanuela; Giovannoli, Cristina; Cravotto, Giancarlo

    2017-03-19

    A number of influencing factors mean that the random substitution of cyclodextrins (CD) in solution is difficult to reproduce. Reaction assembly in mechanochemistry reduces the number of these factors. However, lack of water can improve the reaction outcomes by minimizing the reagent's hydrolysis. High-energy ball milling is an efficient, green and simple method for one-step reactions and usually reduces degradation and byproduct formation. Anionic CD derivatives have successfully been synthesized in the solid state, using a planetary ball mill. Comparison with solution reactions, the solvent-free conditions strongly reduced the reagent hydrolysis and resulted in products of higher degree of substitution (DS) with more homogeneous DS distribution. The synthesis of anionic CD derivatives can be effectively performed under mechanochemical activation without significant changes to the substitution pattern but the DS distributions were considerably different from the products of solution syntheses.

  19. Synthesis of Randomly Substituted Anionic Cyclodextrins in Ball Milling

    Directory of Open Access Journals (Sweden)

    László Jicsinszky

    2017-03-01

    Full Text Available A number of influencing factors mean that the random substitution of cyclodextrins (CD in solution is difficult to reproduce. Reaction assembly in mechanochemistry reduces the number of these factors. However, lack of water can improve the reaction outcomes by minimizing the reagent’s hydrolysis. High-energy ball milling is an efficient, green and simple method for one-step reactions and usually reduces degradation and byproduct formation. Anionic CD derivatives have successfully been synthesized in the solid state, using a planetary ball mill. Comparison with solution reactions, the solvent-free conditions strongly reduced the reagent hydrolysis and resulted in products of higher degree of substitution (DS with more homogeneous DS distribution. The synthesis of anionic CD derivatives can be effectively performed under mechanochemical activation without significant changes to the substitution pattern but the DS distributions were considerably different from the products of solution syntheses.

  20. Thermal Properties of Anionic Polyurethane Composition for Leather Finishing

    Directory of Open Access Journals (Sweden)

    Olga KOVTUNENKO

    2016-09-01

    Full Text Available Thermal properties of anionic polyurethane composition mixed with collagen product and hydrophilic sodium form of montmorillonite for use in the finishing of leather were studied by thermogravimetric method. The thermal indices of processes of thermal and thermo-oxidative destruction depending on the polyurethane composition were determined. The influence of anionic polyurethane composition on thermal behavior of chromium tanned gelatin films that imitate the leather were studied. APU composition with natural compounds increases their thermal stability both in air and in nitrogen atmosphere due to the formation of additional bonds between active groups of APU, protein and chrome tanning agent as the result of chemical reactions between organic and inorganic parts with the new structure formation.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.10043

  1. Rejuvenation of the anion exchanger used for uranium recovery

    International Nuclear Information System (INIS)

    Yan, T.-Y.; Espenscheid, W.F.

    1986-01-01

    The present invention is directed to improving the performance of strong base anionic exchange resins used in uranium recovery that exhibit an undesirable decrease in loading capacity and in total exchange capacity. The invention comprises treating an anionic exchange resin to remove physically adsorbed and occluded fouling agents and to remove poisons which may be chemically bound to active ion groups on the resin. The process involves treating the resin, after the uranium ion exchange stage, with an alkaline carbonate solution, preferably treating the resin with an acid eluant first. The acid treatment dissolves insoluble fouling agents which are physically occluded or adsorbed by the resin and that the weak base treatment augments that result and probably removes poisons which are physically or chemically bound to the resin

  2. Fluorescence enhancement of mazindol in the presence of anionic surfactants

    Science.gov (United States)

    de la Guardia, Miguel; Galdú, Manuel V.

    Experimental conditions for the determination of mazindol {[ 3H] imidazo(2,1-a)isoindol-5-ol-5(4 chlorophenyl-2,5 dihydro)} by u.v. spectroscopy and by spectrofluorimetry have been studied. We have found that the addition of anionic surfactants provides a four-fold increase in the sensitivity of the fluorimetric determination of mazindol at 325 nm. Sensitization parameters of each of the moieties of the anionic surfactant structures have been obtained and it has been found that the triethanolamine lauryl sulphate is the most adequate structure to produce an enhancement of the mazindol fluorescence. A new method for the fluorimetric determination of mazindol that involves prior u.v. irradiation of the samples is proposed which allows a sensitivity increase of 17,500% and a detection limit of 3.6 ng ml -1.

  3. Anion-switchable supramolecular gels for controlling pharmaceutical crystal growth

    Science.gov (United States)

    Foster, Jonathan A.; Piepenbrock, Marc-Oliver M.; Lloyd, Gareth O.; Clarke, Nigel; Howard, Judith A. K.; Steed, Jonathan W.

    2010-12-01

    We describe the use of low-molecular-weight supramolecular gels as media for the growth of molecular crystals. Growth of a range of crystals of organic compounds, including pharmaceuticals, was achieved in bis(urea) gels. Low-molecular-weight supramolecular gelators allow access to an unlimited range of solvent systems, in contrast to conventional aqueous gels such as gelatin and agarose. A detailed study of carbamazepine crystal growth in four different bis(urea) gelators, including a metallogelator, is reported. The crystallization of a range of other drug substances, namely sparfloxacin, piroxicam, theophylline, caffeine, ibuprofen, acetaminophen (paracetamol), sulindac and indomethacin, was also achieved in supramolecular gel media without co-crystal formation. In many cases, crystals can be conveniently recovered from the gels by using supramolecular anion-triggered gel dissolution; however, crystals of substances that themselves bind to anions are dissolved by them. Overall, supramolecular gel-phase crystallization offers an extremely versatile new tool in pharmaceutical polymorph screening.

  4. Inorganic anion exchangers for the treatment of radioactive wastes

    International Nuclear Information System (INIS)

    Dyer, A.; Jamil, M.A.

    1987-07-01

    Inorganic anion exchangers are evaluated for Tc, I and S isotope removal from aqueous nuclear waste streams. Chemical, thermal, and radiation stabilities were examined. Selected exchangers were examined in detail for their selectivities, kinetics and mechanism of the sorption process (especially in NO 3 - , OH - and BO 3 - environments). Cement encapsulation and leaching experiments were made on the exchangers showing most promise for 'radwaste' treatment. (author)

  5. Sheathless capillary electrophoresis-mass spectrometry for anionic metabolic profiling.

    Science.gov (United States)

    Gulersonmez, Mehmet Can; Lock, Stephen; Hankemeier, Thomas; Ramautar, Rawi

    2016-04-01

    The performance of CE coupled on-line to MS via a sheathless porous tip sprayer was evaluated for anionic metabolic profiling. A representative metabolite mixture and biological samples were used for the evaluation of various analytical parameters, such as peak efficiency (plate numbers), migration time and peak area repeatability, and LODs. The BGE, i.e. 10% acetic acid (pH 2.2), previously used for cationic metabolic profiling was now assessed for anionic metabolic profiling by using MS detection in negative ion mode. For test compounds, RSDs for migration times and peak areas were below 2 and 11%, respectively, and plate numbers ranged from 60 000 to 40 0000 demonstrating a high separation efficiency. Critical metabolites with low or no retention on reversed-phase LC could be efficiently separated and selectively analyzed by the sheathless CE-MS method. An injection volume of only circa 20 nL resulted in LODs between 10 and 200 nM (corresponding to an amount of 0.4-4 fmol), which was an at least tenfold improvement as compared to LODs obtained by conventional CE-MS approaches for these analytes. The methodology was applied to anionic metabolic profiling of glioblastoma cell line extracts. Overall, a sheathless CE-MS method has been developed for highly efficient and sensitive anionic metabolic profiling studies, which can also be used for cationic metabolic profiling studies by only switching the MS detection and separation voltage polarity. © 2015 The Authors ELECTROPHORESIS Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  6. Anion Exchange Membranes: Current Status and Moving Forward

    Energy Technology Data Exchange (ETDEWEB)

    Hickner, MA; Herring, AM; Coughlin, EB

    2013-10-29

    This short review is meant to provide the reader with highlights in anion exchange membrane research, describe current needs in the field, and point out promising directions for future work. Anion exchange membranes (AEMs) provide one possible route to low platinum or platinum-free fuel cells with the potential for facile oxidation of complex fuels beyond hydrogen and methanol. AEMs and related stable cationic polymers also have applications in energy storage and other electrochemical technologies such as water electrolyzers and redox flow batteries. While anion exchange membranes have been known for a long time in water treatment applications, materials for electrochemical technology with robust mechanical properties in thin film format have only recently become more widely available. High hydroxide and bicarbonate anion conductivity have been demonstrated in a range of AEM formats, but intrinsic stability of the polymers and demonstration of long device lifetime remain major roadblocks. Novel approaches to stable materials have focused on new types of cations that employ delocalization and steric shielding of the positive center to mitigate nucleophilic attack by hydroxide. A number of promising polymer backbones and membrane architectures have been identified, but limited device testing and a lack of understanding of the degradation mechanisms in operating devices is slowing progress on engineered systems with alkaline fuel cell technology. Our objective is to spur more research in this area to develop fuel cell systems that approach the costs of inexpensive batteries for large-scale applications. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1727-1735, 2013

  7. Closing anion gap without insulin in euglycaemic diabetic ketoacidosis

    Directory of Open Access Journals (Sweden)

    Resham Raj Poudel

    2017-01-01

    Full Text Available Euglycaemic diabetic ketoacidosis (euDKA occurs in patients with poor carbohydrate intake who continue to take insulin. For these patients are not truly in the insulin-deficient state, intravenous fluid resuscitation alone can correct the ketoacidosis without any risk of hypoglycaemia. Diagnosis of euDKA can be missed in inexperienced settings; therefore, calculating anion gap and measuring ketone levels should be practiced in every sick diabetic patient regardless of glucose levels.

  8. Organic resin anion exchangers for the treatment of radioactive wastes

    International Nuclear Information System (INIS)

    Dyer, A.; McGinnes, D.F.

    1988-07-01

    Organic anion exchange resins are evaluated for 99-TcO 4 - (pertechnate) removed from aqueous nuclear waste streams. Chemical, thermal and radiation stabilities were studied. Selected resins were examined in detail for their selectivities in the presence of I - , NO 3 - , SO 4 = , CO 3 = , Cl - and OH - . Ion exchange equilibria and kinetic mechanisms were determined. Preliminary investigations of cement encapsulation in polymer modified form were made and some leach studies carried out. (author)

  9. Thermal behaviour of synthetic pyroaurite-like anionic clay

    Czech Academy of Sciences Publication Activity Database

    Kovanda, F.; Balek, Vladimír; Dorničák, V.; Martinec, P.; Mašláň, M.; Bílková, L.; Koloušek, D.; Bountsewa, I. M.

    2003-01-01

    Roč. 72, č. 1 (2003), s. 727-737 ISSN 1388-6150 R&D Projects: GA MŠk LN00A028; GA ČR GA202/00/0982; GA ČR GA106/02/0523 Institutional research plan: CEZ:AV0Z4032918 Keywords : layered double hydroxide * pyroaurite-like anionic clay * thermal decomposition Subject RIV: CA - Inorganic Chemistry Impact factor: 1.094, year: 2003

  10. Removal of Pesticides from Water by Anionic Clays

    Science.gov (United States)

    Lakraimi, M.; Legrouri, A.; Barroug, A.; de Roy, A.; Besse, J.-P.

    1999-03-01

    The exchange of chloride ions by ions from the pesticide family 2.4-dichlorophe- noxyacetate (2.4D) in ?Zn-Al-Cl? anionic clay was investigated by X-ray diffraction and infrared spectroscopy. The effects of 2.4D concentration in solution and temperature on the ion exchange were studied. The best sample in terms of crystallinity, was obtained at 100°C with a 2.4D concentration corresponding to the solubility limit of the ion in water. This sample was further characterised by chemical analyses and scanning electron microscopy. The anion intercalation was effected without degradation of the pesticide anion. L'échange des ions chlorure par les ions d'une molécule appartenant à la famille des pesticides 2,4-dichlorophénoxyacétate (2,4D) dans l'argile anionique [Zn-Al-Cl] a été étudiée par diffraction des rayons X et spectroscopie infrarouge. Les influences de la concentration en 2,4D de la solution d'échange et de la température ont été étudiées afin d'optimiser les conditions de l'échange. La meilleure cristallinité a été obtenue à 100°C dans une solution 0.004 M en 2,4D. Une phase préparée dans ces conditions a été caractérisée par analyse chimique et microscopie électronique à balayage. L'échange a été réalisée sans dégradation de l'anion pesticide.

  11. Lowest auto-detachment state of the water anion

    International Nuclear Information System (INIS)

    Houfek, K.; Cizek, M.

    2016-01-01

    Because of the abundance of water in living tissue the reactive low-energy electron collisions with the water molecule represent an important step in the radiation damage of cells. In this paper, the potential energy surface of the ground state of the water anion H 2 O - is carefully mapped using multireference configuration interaction (MRCI) calculations for a large range of molecular geometries. Particular attention is paid to a consistent description of both the O - +H 2 and OH - +H asymptotes and to a relative position of the anion energy to the ground state energy of the neutral molecule. The auto-detachment region, where the anion state crosses to the electronic continuum is identified. The local minimum in the direction of the O - + H 2 channel previously reported by Werner et al. [J. Chem. Phys. 87, 2913 (1987)] is found to be slightly off the linear geometry and is separated by a saddle from the auto-detachment region. The auto-detachment region is directly accessible from the OH - +H asymptote. For the molecular geometries in the auto-detachment region and in its vicinity we also performed fixed-nuclei electron-molecule scattering calculations using the R-matrix method. Tuning of consistency of a description of the correlation energy in both the multireference CI and R-matrix calculations is discussed. Two models of the correlation energy within the R-matrix method that are consistent with the quantum chemistry calculations are found. Both models yield scattering quantities in a close agreement. The results of this work will allow a consistent formulation of the nonlocal resonance model of the water anion in a future publication

  12. ANION EXCHANGE METHOD FOR SEPARATION OF METAL VALUES

    Science.gov (United States)

    Hyde, E.K.; Raby, B.A.

    1959-02-10

    A method is described for selectively separating radium, bismuth, poloniums and lead values from a metallic mixture of thc same. The mixture is dissolved in aqueous hydrochloric acid and the acidity is adjusted to between 1 to 2M in hydrochloric acid to form the anionic polychloro complexes of polonium and bismuth. The solution is contacted with a first anion exchange resin such as strong base quaternary ammonia type to selectively absorb the polonium and bismuth leaving the radium and lead in the effluent. The effluent, after treatment in hydrochloric acid to increase the hydrochloric acid concentration to 6M is contacted with a second anion exchange iesin of the same type as the above to selectively adsorb the lead leaving the radium in the effluent. Radium is separately recovered from the effluent from the second exchange column. Lead is stripped from the loaded resin of the second column by treatment with 3M hydrochloric acid solution. The loaded resin of the first column is washed with 8M hydrochloric acid solution to recover bismuth and then treated with strong nitric acid solution to recover polonium.

  13. Fixing of metallic acetates on an anion-exchange resin

    International Nuclear Information System (INIS)

    Brigaudeau-Vaissiere, M.

    1966-06-01

    After giving a brief review of the theoretical principles governing the fixation of anionic complexes of metallic elements on an anion exchange resin, we consider the particular case of uranyl acetate. By plotting the partition curves we have been able to calculate the exchange constants in the resin. By studying the changes in the logarithm of the limiting partition coefficient as a function of the logarithm of the free acetate ion concentration, it has been possible to calculate the dissociation constants for the complexes in solution. The fixation of a large number of metallic acetates has been studied. All the tests have been negative except in the case of mercury. For this reason we have been able to consider the possibility of separating uranium from a certain number of elements. Some of these separations are possible even in the presence of interfering anions such as chlorides which have a greater affinity for the resin than have the acetate ions. In the case of water-ethanol and water-isopropanol mixtures, we have improved the conditions under which copper acetate and mercury acetate may be fixed. This study has enabled us to calculate the dissociation constant for the CuAc 3 - complex in the mixtures water +40% (by weight) isopropanol and water +50% (by weight) isopropanol. It should also make it possible to use separation conditions which could not hitherto be applied in aqueous media. (author) [fr

  14. Dynamical Jahn-Teller effect of fullerene anions

    Science.gov (United States)

    Liu, Dan; Iwahara, Naoya; Chibotaru, Liviu F.

    2018-03-01

    The dynamical Jahn-Teller effect of C60n - anions (n =1 -5) is studied using the numerical diagonalization of the linear pn⊗8 d Jahn-Teller Hamiltonian with the currently established coupling parameters. It is found that in all anions the Jahn-Teller effect stabilizes the low-spin states, resulting in the violation of Hund's rule. The energy gain due to the Jahn-Teller dynamics is found to be comparable to the static Jahn-Teller stabilization. The Jahn-Teller dynamics influences the thermodynamic properties via strong variation of the density of vibronic states with energy. Thus the large vibronic entropy in the low-spin states enhances the effective spin gap of C603 - quenching the spin crossover. From the calculations of the effective spin gap as a function of the Hund's rule coupling, we found that the latter should amount 40 ±5 meV in order to cope with the violation of Hund's rule and to reproduce the large spin gap. With the obtained numerical solutions, the matrix elements of electronic operators for the low-lying vibronic levels and the vibronic reduction factors are calculated for all anions.

  15. Analysis of anions in beer using ion chromatography

    Science.gov (United States)

    Bruce, Jonathan

    2002-01-01

    The majority of anions found in beer are a consequence of impurities derived from the water used during the brewing process. The process of beer manufacture consists of malting, brewing and fermentation followed by maturation before filtration and finally storage. Strict quality control is required because the presence of certain anions outside strictly defined tolerance limits can affect the flavour characteristics of the finished product. The anions present were quantified using the technique of ion chromatography with the Metrohm modular system following sample preparation. The analysis produced a result of the order 200 mg l-1 for chloride, phosphate and sulphate and around 20 mg l-1 for nitrate. If the chloride level exceeds 250 mg l-1, then the sweetness of the beer is enhanced, but yeast flocculation can be hindered. An excess of sulphate can give a sharp, dry edge to hopped beers and excessive amounts of nitrate have been found to harm the yeast metabolism after conversion to the nitrite form. As water is a primary ingredient within beer, its quality and type is a fundamental factor in establishing many of the distinctive regional beers that can be found in the United Kingdom and is thus monitored carefully. PMID:18924733

  16. Anion induced conformational preference of Cα NN motif residues in functional proteins.

    Science.gov (United States)

    Patra, Piya; Ghosh, Mahua; Banerjee, Raja; Chakrabarti, Jaydeb

    2017-12-01

    Among different ligand binding motifs, anion binding C α NN motif consisting of peptide backbone atoms of three consecutive residues are observed to be important for recognition of free anions, like sulphate or biphosphate and participate in different key functions. Here we study the interaction of sulphate and biphosphate with C α NN motif present in different proteins. Instead of total protein, a peptide fragment has been studied keeping C α NN motif flanked in between other residues. We use classical force field based molecular dynamics simulations to understand the stability of this motif. Our data indicate fluctuations in conformational preferences of the motif residues in absence of the anion. The anion gives stability to one of these conformations. However, the anion induced conformational preferences are highly sequence dependent and specific to the type of anion. In particular, the polar residues are more favourable compared to the other residues for recognising the anion. © 2017 Wiley Periodicals, Inc.

  17. Identification of a probable pore-forming domain in the multimeric vacuolar anion channel AtALMT9.

    Science.gov (United States)

    Zhang, Jingbo; Baetz, Ulrike; Krügel, Undine; Martinoia, Enrico; De Angeli, Alexis

    2013-10-01

    Aluminum-activated malate transporters (ALMTs) form an important family of anion channels involved in fundamental physiological processes in plants. Because of their importance, the role of ALMTs in plant physiology is studied extensively. In contrast, the structural basis of their functional properties is largely unknown. This lack of information limits the understanding of the functional and physiological differences between ALMTs and their impact on anion transport in plants. This study aimed at investigating the structural organization of the transmembrane domain of the Arabidopsis (Arabidopsis thaliana) vacuolar channel AtALMT9. For that purpose, we performed a large-scale mutagenesis analysis and found two residues that form a salt bridge between the first and second putative transmembrane α-helices (TMα1 and TMα2). Furthermore, using a combination of pharmacological and mutagenesis approaches, we identified citrate as an "open channel blocker" of AtALMT9 and used this tool to examine the inhibition sensitivity of different point mutants of highly conserved amino acid residues. By this means, we found a stretch within the cytosolic moiety of the TMα5 that is a probable pore-forming domain. Moreover, using a citrate-insensitive AtALMT9 mutant and biochemical approaches, we could demonstrate that AtALMT9 forms a multimeric complex that is supposedly composed of four subunits. In summary, our data provide, to our knowledge, the first evidence about the structural organization of an ion channel of the ALMT family. We suggest that AtALMT9 is a tetramer and that the TMα5 domains of the subunits contribute to form the pore of this anion channel.

  18. Quantitative relationships among plasma lactate, inorganic phosphorus, albumin, unmeasured anions and the anion gap in lactic acidosis.

    Science.gov (United States)

    Figge, James; Bellomo, Rinaldo; Egi, Moritoki

    2018-04-01

    Quantitative relationships among plasma [Lactate], [Pi], [Albumin], unmeasured anions ([UA]) and the anion gap (AG K ) in lactic acidosis (LA) are not well defined. A mathematical model featuring compensatory potassium and chloride shifts and respiratory changes in LA demonstrated: (1) AG K =[Lactate]+Zp×[Pi]+2.4×[Albumin]+constant1+e, where Zp is a function of pH, and e reflects unmeasured anions and cations plus pH-related variations. Eq. (1) can be algebraically rearranged to incorporate the albumin-corrected anion gap, cAG K : (2) cAG K =[Lactate]+Zp×[Pi]+constant2+e. Eq. (1) was tested against 948 data sets from critically ill patients with [Lactate] 4.0mEq/L or greater. AG K and cAG K were evaluated against 12,341 data sets for their ability to detect [Lactate]>4.0mEq/L. Analysis of Eq. (1) revealed r 2 =0.5950, p15mEq/L exhibited a sensitivity of 93.0% [95% CI: 91.3-94.5] in detecting [Lactate]>4.0mEq/L, whereas AG K >15mEq/L exhibited a sensitivity of only 70.4% [67.5-73.2]. Additionally, [Lactate]>4.0mEq/L and cAG K >20mEq/L were each strongly associated with intensive care unit mortality (χ 2 >200, p4.0mEq/L. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  19. Competition of organic anions for furosemide and p-aminohippurate secretion in the rabbit

    Energy Technology Data Exchange (ETDEWEB)

    Bidiville, J.; Roch-Ramel, F.

    1986-05-01

    The excretion of (/sup 14/C)- or (/sup 35/S)furosemide and (/sup 3/H)-p-aminohippurate (PAH) injected within 4 min into the left renal artery of rabbits was measured under brisk mannitol diuresis. The estimated rate of furosemide secretion during the first pass through the left kidney was lower than that of PAH when neither of the two transport processes were saturated: 7.9 and 12.9% of the total amounts injected were secreted per minute, respectively. Different competitive inhibitors were injected i.v. Probenecid (50 mg/kg) inhibited furosemide and PAH secretion by 95 and 80%, respectively. Pyrazinoate at plasma concentrations of 3 to 5 mM had no effect on either anion. Indomethacin (10 mg/kg) depressed furosemide secretion by 24% but had no effect on PAH secretion. PAH at a concentration of 9 to 17 mM in plasma depressed furosemide secretion by only 44 to 66%. Furosemide did not inhibit PAH secretion when infused into the left renal artery at a rate 5000 times higher than PAH. It was concluded that furosemide is secreted partly by the transport system secreting PAH, for which it had only a low affinity, and partly by a transport system for which indomethacin had some affinity. This latter transport system, in turn, differs from that secreting pyrazinoate. The furosemide-induced natriuresis, in both kidneys, was proportional to the urinary excretion rate of furosemide until the fractional excretion of Na+ reached an apparent maximum of 20 to 30%.

  20. Mimicking the cell membrane: bio-inspired simultaneous functions with monovalent anion selectivity and antifouling properties of anion exchange membrane

    Science.gov (United States)

    Zhao, Yan; Liu, Huimin; Tang, Kaini; Jin, Yali; Pan, Jiefeng; der Bruggen, Bart Van; Shen, Jiangnan; Gao, Congjie

    2016-11-01

    A new bio-inspired method was applied in this study to simultaneously improve the monovalent anion selectivity and antifouling properties of anion exchange membranes (AEMs). Three-layer architecture was developed by deposition of polydopamine (PDA) and electro-deposition of N-O-sulfonic acid benzyl chitosan (NSBC). The innermost and outermost layers were PDA with different deposition time. The middle layer was prepared by NSBC. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that PDA and NSBC were successfully modified on the surfaces of AEMs. The contact angle of the membranes indicated an improved hydrophilicity of the modified membranes. A series of electrodialysis experiments in which Cl-/SO42- separation was studied, demonstrating the monovalent anion selectivity of the samples. The Cl-/SO42- permselectivity of the modified membranes can reach up to 2.20, higher than that of the commercial membrane (only 0.78) during 90 minutes in electrodialysis (ED). The increase value of the resistance of the membranes was also measured to evaluate the antifouling properties. Sodium dodecyl benzene sulfonate (SDBS) was used as the fouling material in the ED process and the membrane area resistance of modified membrane increase value of was only 0.08 Ωcm2 30 minutes later.

  1. Radiation Transport

    Energy Technology Data Exchange (ETDEWEB)

    Urbatsch, Todd James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-06-15

    We present an overview of radiation transport, covering terminology, blackbody raditation, opacities, Boltzmann transport theory, approximations to the transport equation. Next we introduce several transport methods. We present a section on Caseology, observing transport boundary layers. We briefly broach topics of software development, including verification and validation, and we close with a section on high energy-density experiments that highlight and support radiation transport.

  2. Anion-coupled Na efflux mediated by the human red blood cell Na/K pump

    International Nuclear Information System (INIS)

    Dissing, S.; Hoffman, J.F.

    1990-01-01

    The red cell Na/K pump is known to continue to extrude Na when both Na and K are removed from the external medium. Because this ouabain-sensitive flux occurs in the absence of an exchangeable cation, it is referred to as uncoupled Na efflux. This flux is also known to be inhibited by 5 mM Nao but to a lesser extent than that inhibitable by ouabain. Uncoupled Na efflux via the Na/K pump therefore can be divided into a Nao-sensitive and Nao-insensitive component. We used DIDS-treated, SO4-equilibrated human red blood cells suspended in HEPES-buffered (pHo 7.4) MgSO4 or (Tris)2SO4, in which we measured 22Na efflux, 35SO4 efflux, and changes in the membrane potential with the fluorescent dye, diS-C3 (5). A principal finding is that uncoupled Na efflux occurs electroneurally, in contrast to the pump's normal electrogenic operation when exchanging Nai for Ko. This electroneutral uncoupled efflux of Na was found to be balanced by an efflux of cellular anions. (We were unable to detect any ouabain-sensitive uptake of protons, measured in an unbuffered medium at pH 7.4 with a Radiometer pH-STAT.) The Nao-sensitive efflux of Nai was found to be 1.95 +/- 0.10 times the Nao-sensitive efflux of (SO4)i, indicating that the stoichiometry of this cotransport is two Na+ per SO4=, accounting for 60-80% of the electroneutral Na efflux. The remainder portion, that is, the ouabain-sensitive Nao-insensitive component, has been identified as PO4-coupled Na transport and is the subject of a separate paper. That uncoupled Na efflux occurs as a cotransport with anions is supported by the result, obtained with resealed ghosts, that when internal and external SO4 was substituted by the impermeant anion, tartrate i,o, the efflux of Na was inhibited 60-80%. This inhibition could be relieved by the inclusion, before DIDS treatment, of 5 mM Cli,o

  3. Study of the simultaneous complexation of a cation and of an anion using functionalized calixarenes; Etude de la complexation simultanee d'un cation et d'un anion par des calixarenes fonctionnalises

    Energy Technology Data Exchange (ETDEWEB)

    Moli, Ch. [CEA Cadarache, Dept. d' Etudes des Dechets, DED, 13 - Saint Paul lez Durance (France)]|[Universite Louis Pasteur, 67 - Strasbourg (France)

    2002-03-01

    The chemical reprocessing of irradiated nuclear fuels leads to the production of high-level radioactive liquid wastes which contain long-lived toxic radioelements. In the framework of the long-term management of these wastes, important research work is carried out for the separation of these radioelements for their further transmutation or immobilization inside specific matrices. These radioelements are present in acid solutions of fission products in the form of cations (cesium), anions (technetium, selenium) and molecules (iodine). Crown calixarenes have been successfully used for the extraction of cesium thanks to their exceptional selectivities. This work is mainly based on the use of the chelating properties of calixarenes for the extraction of anionic radioelements. Calixarenes functionalized by amino-carbon chains have been selected. The synthesis of amine calix[4]arenes and calix[6]arenes is described and their extractive and ionophoretic properties with respect to radioelements are shown using aqueous selective separation techniques like the liquid-liquid extraction and the supported liquid membrane transport. Technetium and selenium are extracted by amine calixarenes from a 10{sup -2} M aqueous solution of nitric acid. At this acidity, no selenium transport is observed, while technetium transport is efficient: the solution is quasi-totally decontaminated in 6 hours. Molecular iodine is efficiently extracted with a simple organic diluent, the 1,2-nitro-phenyl-hexyl-ether, from a strongly concentrated aqueous solution of nitric acid (HNO{sub 3} = 3 M). The transport of iodine becomes faster and more efficient when its concentration in the solution is higher. (J.S.)

  4. Anionic Cerium Oxide Nanoparticles Protect Plant Photosynthesis from Abiotic Stress by Scavenging Reactive Oxygen Species.

    Science.gov (United States)

    Wu, Honghong; Tito, Nicholas; Giraldo, Juan P

    2017-11-28

    Plant abiotic stress leads to accumulation of reactive oxygen species (ROS) and a consequent decrease in photosynthetic performance. We demonstrate that a plant nanobionics approach of localizing negatively charged, sub-11 nm, spherical cerium oxide nanoparticles (nanoceria) inside chloroplasts in vivo augments ROS scavenging and photosynthesis of Arabidopsis thaliana plants under excess light (2000 μmol m -2 s -1 , 1.5 h), heat (35 °C, 2.5 h), and dark chilling (4 °C, 5 days). Poly(acrylic acid) nanoceria (PNC) with a hydrodynamic diameter (10.3 nm)-lower than the maximum plant cell wall porosity-and negative ζ-potential (-16.9 mV) exhibit significantly higher colocalization (46%) with chloroplasts in leaf mesophyll cells than aminated nanoceria (ANC) (27%) of similar size (12.6 nm) but positive charge (9.7 mV). Nanoceria are transported into chloroplasts via nonendocytic pathways, influenced by the electrochemical gradient of the plasma membrane potential. PNC with a low Ce 3+ /Ce 4+ ratio (35.0%) reduce leaf ROS levels by 52%, including hydrogen peroxide, superoxide anion, and hydroxyl radicals. For the latter ROS, there is no known plant enzyme scavenger. Plants embedded with these PNC that were exposed to abiotic stress exhibit an increase up to 19% in quantum yield of photosystem II, 67% in carbon assimilation rates, and 61% in Rubisco carboxylation rates relative to plants without nanoparticles. In contrast, PNC with high Ce 3+ /Ce 4+ ratio (60.8%) increase overall leaf ROS levels and do not protect photosynthesis from oxidative damage during abiotic stress. This study demonstrates that anionic, spherical, sub-11 nm PNC with low Ce 3+ /Ce 4+ ratio can act as a tool to study the impact of oxidative stress on plant photosynthesis and to protect plants from abiotic stress.

  5. Imidazolium-Based Polymeric Materials as Alkaline Anion-Exchange Fuel Cell Membranes

    Science.gov (United States)

    Narayan, Sri R.; Yen, Shiao-Ping S.; Reddy, Prakash V.; Nair, Nanditha

    2012-01-01

    Polymer electrolyte membranes that conduct hydroxide ions have potential use in fuel cells. A variety of polystyrene-based quaternary ammonium hydroxides have been reported as anion exchange fuel cell membranes. However, the hydrolytic stability and conductivity of the commercially available membranes are not adequate to meet the requirements of fuel cell applications. When compared with commercially available membranes, polystyrene-imidazolium alkaline membrane electrolytes are more stable and more highly conducting. At the time of this reporting, this has been the first such usage for imidazolium-based polymeric materials for fuel cells. Imidazolium salts are known to be electrochemically stable over wide potential ranges. By controlling the relative ratio of imidazolium groups in polystyrene-imidazolium salts, their physiochemical properties could be modulated. Alkaline anion exchange membranes based on polystyrene-imidazolium hydroxide materials have been developed. The first step was to synthesize the poly(styrene-co-(1-((4-vinyl)methyl)-3- methylimidazolium) chloride through a free-radical polymerization. Casting of this material followed by in situ treatment of the membranes with sodium hydroxide solutions provided the corresponding hydroxide salts. Various ratios of the monomers 4-chloromoethylvinylbenzine (CMVB) and vinylbenzine (VB) provided various compositions of the polymer. The preferred material, due to the relative ease of casting the film, and its relatively low hygroscopic nature, was a 2:1 ratio of CMVB to VB. Testing confirmed that at room temperature, the new membranes outperformed commercially available membranes by a large margin. With fuel cells now in use at NASA and in transportation, and with defense potential, any improvement to fuel cell efficiency is a significant development.

  6. Chamber transport

    International Nuclear Information System (INIS)

    Olson, Craig L.

    2001-01-01

    Heavy ion beam transport through the containment chamber plays a crucial role in all heavy ion fusion (HIF) scenarios. Here, several parameters are used to characterize the operating space for HIF beams; transport modes are assessed in relation to evolving target/accelerator requirements; results of recent relevant experiments and simulations of HIF transport are summarized; and relevant instabilities are reviewed. All transport options still exist, including (1) vacuum ballistic transport, (2) neutralized ballistic transport, and (3) channel-like transport. Presently, the European HIF program favors vacuum ballistic transport, while the US HIF program favors neutralized ballistic transport with channel-like transport as an alternate approach. Further transport research is needed to clearly guide selection of the most attractive, integrated HIF system

  7. Anion gap, anion gap corrected for albumin, base deficit and unmeasured anions in critically ill patients: implications on the assessment of metabolic acidosis and the diagnosis of hyperlactatemia.

    Science.gov (United States)

    Chawla, Lakhmir S; Shih, Shirley; Davison, Danielle; Junker, Christopher; Seneff, Michael G

    2008-12-16

    Base deficit (BD), anion gap (AG), and albumin corrected anion gap (ACAG) are used by clinicians to assess the presence or absence of hyperlactatemia (HL). We set out to determine if these tools can diagnose the presence of HL using cotemporaneous samples. We conducted a chart review of ICU patients who had cotemporaneous arterial blood gas, serum chemistry, serum albumin (Alb) and lactate(Lac) levels measured from the same sample. We assessed the capacity of AG, BD, and ACAG to diagnose HL and severe hyperlactatemia (SHL). HL was defined as Lac > 2.5 mmol/L. SHL was defined as a Lac of > 4.0 mmol/L. From 143 patients we identified 497 series of lab values that met our study criteria. Mean age was 62.2 +/- 15.7 years. Mean Lac was 2.11 +/- 2.6 mmol/L, mean AG was 9.0 +/- 5.1, mean ACAG was 14.1 +/- 3.8, mean BD was 1.50 +/- 5.4. The area under the curve for the ROC for BD, AG, and ACAG to diagnose HL were 0.79, 0.70, and 0.72, respectively. AG and BD failed to reliably detect the presence of clinically significant hyperlactatemia. Under idealized conditions, ACAG has the capacity to rule out the presence of hyperlactatemia. Lac levels should be obtained routinely in all patients admitted to the ICU in whom the possibility of shock/hypoperfusion is being considered. If an AG assessment is required in the ICU, it must be corrected for albumin for there to be sufficient diagnostic utility.

  8. Ethylene glycol toxicity presenting with non-anion gap metabolic acidosis.

    Science.gov (United States)

    Soghoian, Sari; Sinert, Richard; Wiener, Sage W; Hoffman, Robert S

    2009-01-01

    Ethylene glycol classically produces an elevated anion gap metabolic acidosis. We report a series of patients with ethylene glycol toxicity with a component of non-anion gap metabolic acidosis without known associated confounding factors. A retrospective review of Poison Control Center records were searched more than 8 years (2000-2007) for ethylene glycol and antifreeze. Cases were reviewed and excluded for miscoding, information calls, animal exposures, or non-ingestion exposures. The bicarbonate gap, or delta ratio (DR), was calculated using the formula: DR = (AG - 12)/[24 - measured serum where anion gap (AG) = [Na(+)] - [Cl(-)] - , all in mEq/l. Non-anion gap metabolic acidosis was considered present when the DR anion gap metabolic acidosis at presentation. Their calculated anion gap was 14-28, and measured serum ranged from 2-20 mEq/l. A normal anion gap was present in two patients who presented with non-anion gap metabolic acidosis. The DR ranged from 0.28-0.95. Seven out of 14 patients with non-anion gap metabolic acidosis had elevated serum [Cl(-)]. In the other cases, no explanation for the non-anion gap metabolic acidosis could be determined. The absence of a significant anion gap elevation in the setting of metabolic acidosis after ethylene glycol ingestion without other confounding factors (such as ethanol, lithium carbonate or bromide) has not previously been recognized. Clinicians should be aware of the potential for non-anion gap metabolic acidosis in patients with ethylene glycol toxicity, and should not exclude the diagnosis in patients who present with a non-anion gap metabolic acidosis. Further study is needed to determine the mechanisms by which this occurs.

  9. A comparative study of the proton transport properties of metal (IV ...

    Indian Academy of Sciences (India)

    Unknown

    The transport of protons (H+) between relatively stationary host anions is termed the 'Grothus' or 'free-proton mechanism'. Transport by any of other species is termed as a 'vehicle mechanism'.3 In solids, vehicle mechanisms are usually restricted to materials with open structures (channels, layers) to allow passage of the ...

  10. Report membrane transport of lactic acid in the filamentous fungus Rhizopus

    Science.gov (United States)

    The fungus Rhizopus is frequently used for fermentative production of lactic acid, but little is known about the mechanisms or proteins for transporting this carboxylic acid. Since transport of the lactate anion across the plasma membrane is critical to prevent acidification of the cytoplasm, we ev...

  11. Drug trafficking in mice: In vivo functions of OATP uptake and ABC efflux transporters

    NARCIS (Netherlands)

    Iusuf, D.

    2013-01-01

    In recent years, there has been increasing attention for drug uptake transporters of the Organic Anion-Transporting Polypeptide (human OATP, mouse Oatp, gene names SLCO, Slco) superfamily. Especially the OATP1A and OATP1B subfamilies turn out to have important physiological and pharmacological

  12. Differential expression of genes encoding phosphate transporters contributes to arsenic accumulation in shrub willow (Salix spp.)

    Science.gov (United States)

    Emily E. Puckett; Michelle J. Serpiglia; Alyssa M. DeLeon; Stephanie Long; Rakesh Minocha; Lawrence B. Smart

    2012-01-01

    Studies of arsenate and phosphate uptake by plants in hydroponic and soil systems indicate a common transport mechanism via the phosphate transporters (PHTs) due to structural similarity of the anions. Typically, the presence of phosphate decreases plant uptake and translocation of arsenate in hydroponic solution. This study quantified arsenic (As) uptake related to...

  13. Carbon dioxide transport in alligator blood and its erythrocyte permeability to anions and water

    DEFF Research Database (Denmark)

    Jensen, F B; Wang, T; Jones, D R

    1998-01-01

    contributed about equally in deoxygenated cells. The nonbicarbonate buffer values of RBCs and Hb were high, and the Hb showed a significant fixed acid Haldane effect. Binding of HCO3- on deoxygenation occurred without a change in RBC intracellular pH, revealing equivalence between oxylabile HCO3- and H...

  14. Chemistry of nitrile anions in the interstellar medium

    Energy Technology Data Exchange (ETDEWEB)

    Carles, S.; Le Garrec, J.-L.; Biennier, L. [Institut de Physique de Rennes, Département de Physique Moléculaire, Astrophysique de Laboratoire, UMR CNRS 6251, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex (France); Guillemin, J.-C. [Institut des Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 11 Allée de Beaulieu, CS 50837,35708 Rennes Cedex 7 (France)

    2015-12-31

    Despite the extreme conditions of temperature (down to 10K) and density (down to 100 molecules/cm{sup 3}), the giant molecular clouds and the circumstellar envelopes present a rich and complex chemistry. To date, more than 180 molecules have been detected in the InterStellar Medium (ISM) with a large abundance of nitriles (RC≡N). In addition, several anions have been recently observed in this medium: C{sub 4}H{sup ¯}, C{sub 6}H{sup ¯}, C{sub 8}H{sup ¯}, CN{sup ¯}, C{sub 3}N{sup ¯} and C{sub 5}N{sup ¯}. These last species should play a key role in the molecular growth towards complexity. To explore this hypothesis, their reactivity must be studied in the laboratory. The FALP-MS and the CRESU experimental apparatuses of the Rennes University are able to measure absolute rate coefficient of various chemical reactions, including the ion – molecule reactions, in gas phase at low temperature (from 300K for the FALP-MS down to 15K for the CRESU). Therefore, these experimental tools are particularly adapted to the kinetic studies of reactions potentially involved in the Interstellar Medium. One of the difficulties encountered in experiments with anions is their generation. We describe here the formation of the CN{sup ¯} and C{sub 3}N{sup ¯} anions by dissociative electron attachment on the molecular precursors BrCN and BrC{sub 3}N.

  15. Natural minerals and synthetic materials for sorption of radioactive anions

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Mun Ja; Chun, Kwan Sik; Kim, Seung Soo

    1998-07-01

    Technetium-99 and iodine-129 are fission products with long half-lives, and exist as highly soluble anionic species. Studies on natural and synthetic materials sorbing TcO{sub 4} and/or I have been performed by several researchers. The application of these materials as an additive in the high-level waste disposal has been considered. The iron- or sulfide-containing minerals such as metal iron, iron powder, stibnite and pyrrhotite show a high capacity for TcO{sub 4} sorption. And the small amounts of activated carbon are reported to have high distribution coefficients recently. In the iodine sorption studies, sulfide-, copper-, lead- or mercury-containing minerals can be a candidate. Pyrite, chalcopyrite, galena, Cu{sub 2}S and CuS reveal a high capacity for I sorption. The synthetic materials were found to have high sorption capacity and compensate the defects of natural minerals, which contain hydrous oxides such as zirconium oxide, aluminium oxide and mercarbide. The mercarbide has the high distribution coefficients for the sorption of TcO{sub 4} and I. Recently it was proposed that the synthetic clay, hydrotalcite, could be useful for the fixation of anion. However, to determine the applicability of those natural and synthetic materials as an additive to a buffer or backfill material for sorption of TcO{sub 4} and/or I, the sorption behavior of the anions on those materials under the repository conditions should be identified. (author). 32 refs., 21 tabs., 10 figs

  16. REMOVAL OF ANIONIC SURFACTANTS FROM WASTEWATER BY MAGNETIC MINERAL SORBENTS

    Directory of Open Access Journals (Sweden)

    Oksana Vladimirova Makarchuk

    2016-07-01

    Full Text Available The simplest and most effective method of removing low concentrations of anionic surfactants such as sodium dodecyl benzenesulfonate (SDBS and sodium lauryl sulfate (SLS is adsorption. Among adsorbents the natural clays are cheap and promising for these purposes. However, there are significant difficulties in removal of spent sorbent after the adsorption process. So, the creation of magnetic sorbents that can be effectively removed from water after sorption by magnetic separation will be a successful decision. The aim of this investigation is the creation of cheap and efficient magnetic sorbents based on natural clays and magnetite for anionic surfactant removal from wastewater. We have synthesized a series of magnetic sorbents from different natural clays with a content of magnetite from 2 to 10 wt%. The ability of magnetic sorbents to remove SDBS and SLS from aqueous solutions has been studied for different adsorbate concentrations by varying the amount of adsorbent, temperature and shaking time. Thermodynamic parameters were calculated from the slope and intercept of the linear plots of ln K against 1/T. Analysis of adsorption results obtained at different temperatures showed that the adsorption pattern on magnetic sorbents correspond to the Langmuir isotherm. It is shown that with increasing the content of magnetite in the magnetic sorbents improves not only their separation from water by magnetic separation, but adsorption capacity to SDBS and SLS. Thus, we obtained of cheap magnetic sorbents based on natural clays and magnetite by the easy way, which not only quickly separated from the solution by magnetic separation, but effectively remove anionic surfactants.

  17. Adsorption and desorption dynamics of citric acid anions in soil

    KAUST Repository

    Oburger, E.

    2011-07-26

    The functional role of organic acid anions in soil has been intensively investigated, with special focus on (i) microbial respiration and soil carbon dynamics, (ii) nutrient solubilization or (iii) metal detoxification and reduction of plant metal uptake. Little is known about the interaction dynamics of organic acid anions with the soil matrix and the potential impact of adsorption and desorption processes on the functional significance of these effects. The aim of this study was to characterize experimentally the adsorption and desorption dynamics of organic acid anions in five agricultural soils differing in iron and aluminium oxide contents and using citrate as a model carboxylate. Results showed that both adsorption and desorption processes were fast in all soils, reaching a steady state within approximately 1 hour. However, for a given total soil citrate concentration (ct) the steady state was critically dependent on the starting conditions of the experiment, whether most of the citrate was initially present in solution (cl) or held on the solid phase (cs). Specifically, desorption-led processes resulted in significantly smaller steady-state solution concentrations than adsorption-led processes, indicating that hysteresis occurred. As it is not possible to distinguish between different adsorption and desorption pools in soil experimentally, a new dynamic hysteresis model that relies only on measured soil solution concentrations was developed. The model satisfactorily explained experimental data and was able to predict dynamic adsorption and desorption behaviour. To demonstrate its use, we applied the model to two relevant situations involving exudation and microbial degradation. The study highlighted the complex nature of citrate adsorption and desorption dynamics in soil. We conclude that existing models need to incorporate both temporal and hysteresis components to describe realistically the role and fate of organic acids in soil processes. © 2011 The

  18. Fixation of metallic sulfosalicylate complexes on an anionic exchange resin

    International Nuclear Information System (INIS)

    Cahuzac, S.

    1969-06-01

    Since sulfosalicylate ions have acid-base properties, sulfosalicylate complexes have an apparent stability which varies with the ph. As a result, the fixation of sulfo-salicylates on an anionic exchange resin depends on the ph of the solution in equilibrium with the resin. This research has been aimed at studying the influence of the ph on the fixation on an anionic exchange resin (Dowex 1 x 4) of sulfosalicylate anions on the one hand, and of metallic sulfosalicylate complexes on the other hand. In the first part of this work, a determination has been made, by frontal analysis of the distribution of sulfosalicylate ions in the resin according to the total sulfosalicylate I concentration in the aqueous solution in equilibrium with the resin. The exchange constants of these ions between the resin and the solution have been calculated. In the second part, a study has been made of the fixation of anionic sulfosalicylate complexes of Fe(III), Al(III), Cr(III), Cu(II), Ni(II), Co(II), Zn(II), Mn(II), Cd(II), Fe(II) and UO 2 2+ . By measuring the partition coefficients of these different elements between the resin and the solution it has been possible to give interpretation for the modes of fixation of the metallic ions, and to calculate their exchange constant between the resin and the solution. The relationship has been established for each metallic element studied, between its partition coefficient, the ph and the total concentration of the complexing agent in solution. Such a relationship makes it possible to predict, for given conditions, the nature of the species in solution and in the resin, as well as the partition coefficient of a metallic, element. Finally, in the third part of the work, use has been made of results obtained previously, to carry out some separations (Ni 2+ - Co 2+ ; Ni 2+ - Co 2+ - Cu 2+ ; UO 2 2+ - Fe 3+ ; UO 2 2+ - Cr 3+ ; UO 2 2+ - Cu 2+ ; UO 2 2+ - Ni 2+ ; UO 2 2+ - Co 2+ ; UO 2 2+ - Mn 2+ and UO 2 2+ - Cd 2+ ), as well as the purification

  19. Local impermeant anions establish the neuronal chloride concentration

    DEFF Research Database (Denmark)

    Glykys, J; Dzhala, V; Egawa, K

    2014-01-01

    Neuronal intracellular chloride concentration [Cl(-)](i) is an important determinant of γ-aminobutyric acid type A (GABA(A)) receptor (GABA(A)R)-mediated inhibition and cytoplasmic volume regulation. Equilibrative cation-chloride cotransporters (CCCs) move Cl(-) across the membrane, but accumulat......Neuronal intracellular chloride concentration [Cl(-)](i) is an important determinant of γ-aminobutyric acid type A (GABA(A)) receptor (GABA(A)R)-mediated inhibition and cytoplasmic volume regulation. Equilibrative cation-chloride cotransporters (CCCs) move Cl(-) across the membrane...... anions determine the homeostatic set point for [Cl(-)], and hence, neuronal volume and the polarity of local GABA(A)R signaling....

  20. Review: equipment for anionic surfactant manufacture from oil palm

    Directory of Open Access Journals (Sweden)

    Jesús Alfonso Torres Ortega

    2010-05-01

    Full Text Available In the present study is performed a review of the current processes of sulfonation of various raw materials for determine the process conditions in order to present the state of the art of sulfonation processes for the manufacture of anionic surfactants. There has been a scientific literature with emphasis on several aspects: Technology, sulfonation reactors and operating conditions in the process, analytical techniques for monitoring the reaction degree, the mathematical models proposed in the literature for the sulfonation/sulfation in tubular absorbers, patenting and specialized industry publications in this area.

  1. Quenching ofp-Cyanophenylalanine Fluorescence by Various Anions.

    Science.gov (United States)

    Pazos, Ileana M; Roesch, Rachel M; Gai, Feng

    2013-03-20

    To expand the spectroscopic utility of the non-natural amino acid p -cyanophenylalanine (Phe CN ), we examine the quenching efficiencies of a series of commonly encountered anions toward its fluorescence. We find that iodide exhibits an unusually large Stern-Volmer quenching constant, making it a convenient choice in Phe CN fluorescence quenching studies. Indeed, using the villin headpiece subdomain as a testbed we demonstrate that iodide quenching of Phe CN fluorescence offers a convenient means to reveal protein conformational heterogeneity. Furthermore, we show that the amino group of Phe CN strongly quenches its fluorescence, suggesting that Phe CN could be used as a local pH sensor.

  2. Electronic structure and spectra of the peroxynitrite anion

    Science.gov (United States)

    Krauss, M.

    1994-05-01

    The planar cis conformer is calculated as lowest in energy but the trans is sufficiently close that both species may be present at room temperature. The difference in the peak absorption energy for the strong 1 1A' → 2 1A' transition is calculated to be sufficiently large between the conformers to distinguish them or determine their composition. The transition is dissociative in the gas phase but in the solution photo-isomerization is possible to the much more stable nitrate anion. Thermal conversion in the gas phase from cis to trans is calculated to require 65kJ by rotation about the NO bond.

  3. Sustainable Transportation

    DEFF Research Database (Denmark)

    Hall, Ralph P.; Gudmundsson, Henrik; Marsden, Greg

    2014-01-01

    that relate to the construction and maintenance of transportation infrastructure and the operation or use of the different transportation modes. The concept of sustainable transportation emerged in response to these concerns as part of the broader notion of sustainable development. Given the transportation...... sector’s significant contribution to global challenges such as climate change, it is often said that sustainable development cannot be achieved without sustainable transportation....

  4. Optical recognition of anions by ruthenium(II)-bipyridine-calix[4]arene system.

    Science.gov (United States)

    Mareeswaran, Paulpandian Muthu; Babu, Eththilu; Rajagopal, Seenivasan

    2013-09-01

    The two t-butylcalix[4]arene attached ruthenium(II)-bipyridine complexes (Rubc2 and Rubc3) has been synthesized and the anion recognition studies have been carried out using emission techniques. The binding of anions, which are sensed by the complexes, are studied by UV-visible and emission techniques. The complex Rubc2 recognizes the Cl(-), H2PO4 (-) and AcO(-) anions. The complex Rubc3 recognizes the Br(-) and AcO(-) anions. The AcO(-) quenches the emission intensity of both two complexes but the other anion increases the emission intensity of the complexes. The excited state lifetime and transient absorption studies were carried out the AcO(-) facilitates non radiative pathway. The other anions stabilize the excited state and facilitate the radiative pathway.

  5. Closing the anion gap: contribution of D-lactate to diabetic ketoacidosis.

    Science.gov (United States)

    Lu, Jianxin; Zello, Gordon A; Randell, Edward; Adeli, Khosrow; Krahn, John; Meng, Qing H

    2011-01-30

    A high anion gap in diabetic ketoacidosis (DKA) suggests that some unmeasured anions must contribute to the generation of the anion gap. We investigated the contribution of D-lactate to the anion gap in DKA. Diabetic patients with and without DKA and high anion gap were recruited. Plasma D-lactate was quantified by HPLC. Plasma methylglyoxal was assayed by liquid chromatography-tandem mass spectrometry. The plasma fasting glucose, β-hydroxybutyrate, and blood HbA1c levels were highly elevated in DKA. Plasma anion gap was significantly increased in DKA (20.59±6.37) compared to either the diabetic (7.50±1.88) or the control group (6.53±1.75) (panion gap (r=0.686, panion gap in DKA. Laboratory monitoring of d-lactate will provide valuable information for assessment of patients with DKA. Copyright © 2010 Elsevier B.V. All rights reserved.

  6. The Clinical Efficacy, Safety and Functionality of Anion Textile in the Treatment of Atopic Dermatitis

    OpenAIRE

    Kim, Sang Hyun; Hwang, Sung Hwan; Hong, Soon Kwon; Seo, Jong Keun; Sung, Ho Suk; Park, Sung Wook; Shin, Jeong Hwan

    2012-01-01

    Background Several previous studies have suggested the improvement of atopic dermatitis (AD) in response to special fabrics. In particular, beneficial effects have been reported, following the use of anion textiles. Objective The purpose of this study is to evaluate the effectiveness and safety of an anion textile in patients suffering from AD. Methods We compared an anion textile with a pure cotton textile. Fifty-two atopic patients (n=52) were enrolled and divided into two groups. The patie...

  7. Dithranol-Anion: UV/Vis-Spektrum und chemische Reaktivität

    OpenAIRE

    Retzow, A.; Wiegrebe, Wolfgang

    1985-01-01

    Dithranol and its monoacetate as well as aloin and 9-hydroxyanthracen show a bathochromically shifted band in their electronexcitation spectra, when they are taken in alkaline solutions. The spectrum of aloin-anion was correlated with the isomerisation of aloin B into aloin A. These results and the Diels-Alder-reactivity of dithranol-anion indicate that R a a b' s biochemically highly active species, derived from dithranol, is its anion.

  8. [The plasma anion gap is a useful tool for evaluating children with metabolic acidosis].

    Science.gov (United States)

    Pivkovska, Julijana; Born, Peter; Kvist, Nina Eva; Nygaard, Ulrikka

    2013-10-14

    Metabolic acidosis occurs frequently in hospitalized children. The causes are many and often apparent from the history and physical examination. However, if the aetiology is unclear, the plasma anion gap is a useful tool for evaluating patients with metabolic acidosis. In this case report we describe two children in which the aetiology to the metabolic acidosis was unknown, one with normal anion gap who was diagnosed with renal tubular acidosis, and one with increased anion gap acidosis due to D-lactic acidosis.

  9. Optical Sensing of Anions via Supramolecular Recognition with Biimidazole Complexes.

    Science.gov (United States)

    Rommel, Sebastian A; Sorsche, Dieter; Fleischmann, Maximilian; Rau, Sven

    2017-12-22

    Phosphorescent metal complexes with peripheral N-H donor functionalities have attracted great attention as potential molecular sensing units for anionic species lately. In this contribution we discuss the development and potential of anion recognition and sensing features of recent examples of luminescent 2,2'-biimidazole complexes of ruthenium(II), iridium(III), osmium(II) and cobalt(III). The general dependency of photophysical features in these complexes regarding the acid-base chemistry of the peripheral N-H functionalities will be outlined as a basic requirement for optical ion recognition. Systematic strategies for the tuning and specific improvement by synthetic means will be discussed regarding recent reports. With respect to their distinct photophysical features, different transition metals are considered individually to demonstrate particular trends regarding ligand modification within the respective groups. In summary, this review elucidates the current state-of-the-art and future potential of the versatile class of 2,2'-biimidazole based sensor chromophores. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Improved Performance of Ionic Liquid Supercapacitors by using Tetracyanoborate Anions.

    Science.gov (United States)

    Martins, Vitor L; Rennie, Anthony J R; Sanchez-Ramirez, Nedher; Torresi, Roberto M; Hall, Peter J

    2018-02-01

    Supercapacitors are energy storage devices designed to operate at higher power densities than conventional batteries, but their energy density is still too low for many applications. Efforts are made to design new electrolytes with wider electrochemical windows than aqueous or conventional organic electrolytes in order to increase energy density. Ionic liquids (ILs) with wide electrochemical stability windows are excellent candidates to be employed as supercapacitor electrolytes. ILs containing tetracyanoborate anions [B(CN) 4 ] offer wider electrochemical stability than conventional electrolytes and maintain a high ionic conductivity (6.9 mS cm -1 ). Herein, we report the use of ILs containing the [B(CN) 4 ] anion for such an application. They presented a high maximum operating voltage of 3.7 V, and two-electrode devices demonstrate high specific capacitances even when operating at relatively high rates (ca. 20 F g -1 @ 15 A g -1 ). This supercapacitor stored more energy and operated at a higher power at all rates studied when compared with cells using a commonly studied ILs.

  11. Review of cell performance in anion exchange membrane fuel cells

    Science.gov (United States)

    Dekel, Dario R.

    2018-01-01

    Anion exchange membrane fuel cells (AEMFCs) have recently received increasing attention since in principle they allow for the use of non-precious metal catalysts, which dramatically reduces the cost per kilowatt of power in fuel cell devices. Until not long ago, the main barrier in the development of AEMFCs was the availability of highly conductive anion exchange membranes (AEMs); however, improvements on this front in the past decade show that newly developed AEMs have already reached high levels of conductivity, leading to satisfactory cell performance. In recent years, a growing number of research studies have reported AEMFC performance results. In the last three years, new records in performance were achieved. Most of the literature reporting cell performance is based on hydrogen-AEMFCs, although an increasing number of studies have also reported the use of fuels others than hydrogen - such as alcohols, non-alcohol C-based fuels, as well as N-based fuels. This article reviews the cell performance and performance stability achieved in AEMFCs through the years since the first reports in the early 2000s.

  12. Dynamics of anion-molecule reactions at low energy

    Energy Technology Data Exchange (ETDEWEB)

    Mikosch, J.

    2007-11-15

    Anion-molecule reactions must find their way through deeply bound entrance and exit channel complexes separated by a central barrier. This results in low reaction rates and rich dynamics since direct pathways compete with the formation of transient intermediates. In this thesis we examine the probability of proton transfer to a small anion and transient lifetimes of a thermoneutral bimolecular nucleophilic substitution (S{sub N}2) reaction at well defined variable temperature down to 8 Kelvin in a multipole trap. The observed strong inverse temperature dependence is attributed to the deficit of available quantum states in the entrance channel at decreasing temperature. Furthermore we investigate scattering dynamics of S{sub N}2 reactions at defined relative energy between 0.4 and 10 eV by crossed beam slice imaging. A weakly exothermic reaction with high central barrier proceeds via an indirect, complex-mediated mechanism at low relative energies featuring high internal product excitation in excellent quantitative agreement with a statistical model. In contrast, direct backward scattering prevails for higher energies with product velocities close to the kinematical cutoff. For a strongly exothermic reaction, competing S{sub N}2-, dihalide- and proton transfer-channels are explored which proceed by complex mediation for low energy and various rebound-, grazing- and collision induced bond rupture-mechanisms at higher energy. From our data and a collaboration with theory we identify a new indirect roundabout S{sub N}2 mechanism involving CH{sub 3}-rotation. (orig.)

  13. Anion exchange in mixed solvent systems Part 7

    International Nuclear Information System (INIS)

    Koprda, V.

    1976-01-01

    The diffusion of chlorocomplexes of some corrosion and fission products in anion exchange beads has been studied in mixed solvent media. The effects of variables on the kinetics of the exchange process by the batch and flow technique were examined. The strongly basic anion exchanger Dowex 2x8 in its Cl - form was used in organic solvent-water-hydrochloric acid solutions. The dependence of the exchange rate on temperature, the viscosity of the solution, the mean resin particle diameter and the composition of the solution was studied. Film and particle diffusion coefficients were calculated from the experimental data. The results provide valuable data for the design of separation procedures. The most perspective parameters affecting substantially the kinetics of ion exchange and the dynamic behaviour of ionic species in chromatographic column seem to be temperature temperature, viscosity of solution, resin particle diameter and the quantity of organic solvent in mixed solution. The results of the kinetics of chlorocomplexes of trace radionuclides of corrosion and fission products provide valuable data for the design of separation procedures from mixed solvents. (T.G.)

  14. Diffusion of anions and cations in compacted sodium bentonite

    International Nuclear Information System (INIS)

    Muurinen, A.

    1994-02-01

    The thesis presents the results of studies on the diffusion mechanisms of anions and cations in compacted sodium bentonite, which is planned to be used as a buffer material in nuclear waste disposal in Finland. The diffusivities and sorption factors were determined by tracer experiments. The pore volume accessible to chloride, here defined as effective porosity, was determined as a function of bentonite density and electrolyte concentration in water, and the Stern-Gouy double-layer model was used to explain the observed anion exclusion. The sorption of Cs + and Sr 2+ was studied in loose and compacted bentonite samples as a function of the electrolyte concentration in solution. In order to obtain evidence of the diffusion of exchangeable cations, defined as surface diffusion, the diffusivities of Cs + and Sr 2+ in compacted bentonite were studied as a function of the sorption factor, which was varied by electrolyte concentration in solution. The measurements were performed both by a non-steady state method and by a through-diffusion method. (89 refs., 35 fig., 4 tab.)

  15. Absorption spectrum of the firefly luciferin anion isolated in vacuo.

    Science.gov (United States)

    Støchkel, Kristian; Milne, Bruce F; Brøndsted Nielsen, Steen

    2011-03-24

    The excited-state physics of the firefly luciferin anion depends on its chemical environment, and it is therefore important to establish the intrinsic behavior of the bare ion. Here we report electronic absorption spectra of the anion isolated in vacuo obtained at an electrostatic ion storage ring and an accelerator mass spectrometer where ionic dissociation is monitored on a long time scale (from 33 μs and up to 3 ms) and on a short time scale (0-3 μs), respectively. In the ring experiment the yield of all neutrals (mainly CO(2)) as a function of wavelength was measured whereas in the single pass experiment, the abundance of daughter ions formed after loss of CO(2) was recorded to provide action spectra. We find maxima at 535 and 265 nm, and that the band shape is largely determined by the sampling time interval, which is due to the kinetics of the dissociation process. Calculations at the TD-B3LYP/TZVPP++ level predict maximum absorption at 533 and 275 nm for the carboxylate isomer in excellent agreement with the experimental findings. The phenolate isomer lies higher in energy by 0.22 eV, and also its absorption maximum is calculated to be at 463 nm, which is far away from the experimental value. Our data serve to benchmark future theoretical models for bioluminescence from fireflies.

  16. Dynamics of anion-molecule reactions at low energy

    International Nuclear Information System (INIS)

    Mikosch, J.

    2007-11-01

    Anion-molecule reactions must find their way through deeply bound entrance and exit channel complexes separated by a central barrier. This results in low reaction rates and rich dynamics since direct pathways compete with the formation of transient intermediates. In this thesis we examine the probability of proton transfer to a small anion and transient lifetimes of a thermoneutral bimolecular nucleophilic substitution (S N 2) reaction at well defined variable temperature down to 8 Kelvin in a multipole trap. The observed strong inverse temperature dependence is attributed to the deficit of available quantum states in the entrance channel at decreasing temperature. Furthermore we investigate scattering dynamics of S N 2 reactions at defined relative energy between 0.4 and 10 eV by crossed beam slice imaging. A weakly exothermic reaction with high central barrier proceeds via an indirect, complex-mediated mechanism at low relative energies featuring high internal product excitation in excellent quantitative agreement with a statistical model. In contrast, direct backward scattering prevails for higher energies with product velocities close to the kinematical cutoff. For a strongly exothermic reaction, competing S N 2-, dihalide- and proton transfer-channels are explored which proceed by complex mediation for low energy and various rebound-, grazing- and collision induced bond rupture-mechanisms at higher energy. From our data and a collaboration with theory we identify a new indirect roundabout S N 2 mechanism involving CH 3 -rotation. (orig.)

  17. Anion exchange fractionation of serum proteins versus albumin elimination.

    Science.gov (United States)

    Sahab, Ziad J; Iczkowski, Kenneth A; Sang, Qing-Xiang Amy

    2007-09-01

    Elimination of albumin, constituting more than 50% of total serum proteins, allows increased protein loads on immobilized pH gradient (IPG) gels and better visualization of low-abundance proteins; however, it may result in the loss of albumin-bound low-abundance proteins. In this study, we report the prefractionation of serum proteins by batch anion exchange chromatography into three fractions: one containing proteins with isoelectric points (pI values) higher than the pI of albumin, a second fraction containing proteins with pI values in the same range as the pI of albumin, and a third fraction containing proteins with pI values lower than the pI of albumin. This procedure uses common instrumentation, is carried out under denaturing conditions, and takes less than 30min. We also report the loss of a clinically established prostate cancer serum biomarker, prostate-specific antigen (PSA), after albumin is eliminated using two commercially available albumin elimination kits: one that uses Cibacron Blue F3GA, which achieves albumin depletion through dye-ligand binding, and one that uses specific albumin antibody. The loss of PSA secondary to albumin elimination exceeded that after batch anion exchange serum sample prefractionation.

  18. Effect of ethyleneoxide groups of anionic surfactants on lipase activity.

    Science.gov (United States)

    Magalhães, Solange S; Alves, Luís; Sebastião, Marco; Medronho, Bruno; Almeida, Zaida L; Faria, Tiago Q; Brito, Rui M M; Moreno, Maria J; Antunes, Filipe E

    2016-09-01

    The use of enzymes in laundry and dish detergent products is growing. Such tendency implies dedicated studies to understand surfactant-enzyme interactions. The interactions between surfactants and enzymes and their impact on the catalytic efficiency represent a central problem and were here evaluated using circular dichroism, dynamic light scattering, and enzyme activity determinations. This work focuses on this key issue by evaluating the role of the ethyleneoxide (EO) groups of anionic surfactants on the structure and activity of a commercial lipase, and by focusing on the protein/surfactant interactions at a molecular level. The conformational changes and enzymatic activity of the protein were evaluated in the presence of sodium dodecyl sulfate (SDS also denoted as SLE 0 S) and of sodium lauryl ether sulfate with two EO units (SLE 2 S). The results strongly suggest that the presence of EO units in the surfactant polar headgroup determines the stability and the activity of the enzyme. While SDS promotes enzyme denaturation and consequent loss of activity, SLE 2 S preserves the enzyme structure and activity. The data further highlights that the electrostatic interactions among the protein groups are changed by the presence of the adsorbed anionic surfactants being such absorption mainly driven by hydrophobic interactions. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1276-1282, 2016. © 2016 American Institute of Chemical Engineers.

  19. Hyperchloremic, normal anion-gap, metabolic acidosis due to topiramate.

    Science.gov (United States)

    Mathews, Kathryn D; Stark, Jennifer E

    2008-08-01

    A rare adverse effect observed after dose escalation of topiramate therapy is discussed. A review of published cases, monitoring recommendations, and important counseling information for patients who are prescribed topiramate are described. A 37-year-old man hospitalized for mental status changes and possible seizure developed hyperchloremic, normal anion-gap, metabolic acidosis. His medical history was significant for AIDS, progressive multifocal leukoencephalopathy, a cerebrovascular accident, a seizure disorder for the past three years, and a pulmonary embolism five months before being admitted to the hospital. The patient was also taking topiramate for two months before being hospitalized for his seizure disorder. His dosage was increased after admission, but no changes were made to his other medications. The only new medication initiated was cefotaxime for 14 days to treat pneumonia. During the following 8 days, the patient continued to receive increased dosages of topiramate. His serum chloride concentration increased daily and his serum bicarbonate decreased. Topiramate was identified as the cause and was discontinued the next day. Six other cases of metabolic acidosis in adults are reviewed, as well as risk factors for metabolic acidosis. After receiving increased dosages of topiramate, a 37-year-old man developed hyperchloremic, normal anion-gap, metabolic acidosis, which resolved after discontinuation of the drug.

  20. Model-based analysis of anion-exchanger positioning in direct methanol fuel cell systems

    Science.gov (United States)

    Kraus, Maik; Schröder, Daniel; Krewer, Ulrike

    2014-09-01

    In this work we present a model based study to investigate the presence of anion exchangers in direct methanol fuel cell (DMFC) systems. It is well known that environmental or fuel impurities lead to accumulation of harmful anions, such as chloride, in the system. However, due to DMFC anodic reaction, a carbonate system is present. These corbanate anions have to be taken into account for the anion exchanger design and placement as well as for the system operation strategy with and without anion exchanger, which is the objective of this study. For this purpose, the expected amount of harmful chloride ions in a DMFC system is estimated, and that of carbonate ions is calculated with a model of the carbonate system in a DMFC system. The predicition of durability and dimensions of an anion exchanger is based on a monovalent anion exchange model. The design of gas liquid separators in the DMFC system has a major influence on the amount of dissolved carbon dioxide, which is crucial for durability and dimension of a system integrated anion exchanger. Finally, feasible positions of anion exchanger in a DMFC system are elaborated to fulfill the needs for long term and stable DMFC operation.

  1. Removal of 125I from radioactive experimental waste with an anion exchange paper membrane

    International Nuclear Information System (INIS)

    The behavior of radioactive iodide and chloride ions through an anion exchange paper membrane to remove 125 I from radioactive experimental waste has been studied with nonequilibrium thermodynamic analyses. Anion exchange paper membrane was found to be electroconductively more permeable to iodide ion than to chloride ion. The iodide ion bound more strongly to the anion exchange site within a membrane phase than the chloride ion by more than twice. The results suggested that an anion exchange paper membrane was appropriate for the filtration removal system

  2. Low oxidation state aluminum-containing cluster anions: Cp∗AlnH-, n = 1-3

    Science.gov (United States)

    Zhang, Xinxing; Ganteför, Gerd; Eichhorn, Bryan; Mayo, Dennis; Sawyer, William H.; Gill, Ann F.; Kandalam, Anil K.; Schnöckel, Hansgeorg; Bowen, Kit

    2016-08-01

    Three new, low oxidation state, aluminum-containing cluster anions, Cp*AlnH-, n = 1-3, were prepared via reactions between aluminum hydride cluster anions, AlnHm-, and Cp*H ligands. These were characterized by mass spectrometry, anion photoelectron spectroscopy, and density functional theory based calculations. Agreement between the experimentally and theoretically determined vertical detachment energies and adiabatic detachment energies validated the computed geometrical structures. Reactions between aluminum hydride cluster anions and ligands provide a new avenue for discovering low oxidation state, ligated aluminum clusters.

  3. Anion-tunable control of thermal Z→E isomerisation in basic azobenzene receptors.

    Science.gov (United States)

    Dąbrowa, Kajetan; Niedbała, Patryk; Jurczak, Janusz

    2014-12-25

    Herein, we report that thermal Z→E isomerisation of simple azobenzene urea derivatives is selectively and predictably controlled by anion binding. The rate of this process depends strictly on the anion concentration and its binding affinity to the Z-isomer of the azobenzene host, i.e. increased rate constants are observed for higher anion concentration as well as for more strongly bound guests. The origin of this phenomenon is attributed to the electron density transfer from the anion to the host π-system, resulting in increased repulsion between the lone electron pairs in the N=N bond.

  4. Gas-Phase Anionic ?-Adduct (Trans)formations in Heteroaromatic Systems1

    OpenAIRE

    Zimnicka, Magdalena; Danikiewicz, Witold

    2015-01-01

    Anions of nitroderivatives of thiophene and furan were subjected to the reactions with selected C-H acids in the gas phase. Various structures and reaction pathways were proposed for the observed ionic products. In general, the reactions of heteroaromatic anions with C-H acids may be divided into three groups, depending on the proton affinity difference between C-H acid?s conjugate base and heteroaromatic anion (?PA). The proton transfer from C-H acid to heteroaromatic anion is a dominant pro...

  5. Negative anion gap metabolic acidosis in salicylate overdose--a zebra!

    Science.gov (United States)

    Kaul, Viren; Imam, Syed Haider; Gambhir, Harvir Singh; Sangha, Arindam; Nandavaram, Sravanthi

    2013-10-01

    Salicylate poisoning classically results in an increased anion gap metabolic acidosis. We discuss a case of normal anion gap metabolic acidosis despite elevated serum salicylate concentration. This diagnostic dilemma stemmed from aberrant reading of salicylate ions by analyzer electrodes as chloride ions leading to falsely negative anion gap. On review, this phenomenon is found to be possible with a number of commonly used analyzers. In emergency department settings, high level of clinical suspicion for salicylate poisoning should be maintained, and metabolic acidosis with normal anion gap should not be used to rule out salicylate overdose. This can prevent significant avoidable morbidity and mortality.

  6. Spurious Hyperchloremia and Negative Anion Gap in a Child with Refractory Epilepsy.

    Science.gov (United States)

    Chegondi, Madhuradhar; Totapally, Balagangadhar R

    2016-01-01

    We report a case with spurious hyperchloremia with negative anion gap in a child who was taking potassium bromide for refractory epilepsy. Blood chemistry showed a high chloride level (171 mEq/L) and a negative anion gap (-52 mEq/L). Plasma chloride concentration is measured by an ion-selective electrode method; however the presence of other anions like bromide and iodides can interfere with chloride level and largely overestimates the chloride concentration. Thus hyperchloremia with a negative anion gap is a clue to the diagnosis of halides like bromide and iodide ingestion.

  7. The copper-catalysed Suzuki-Miyaura coupling of alkylboron reagents: disproportionation of anionic (alkyl)(alkoxy)borates to anionic dialkylborates prior to transmetalation.

    Science.gov (United States)

    Basnet, Prakash; Thapa, Surendra; Dickie, Diane A; Giri, Ramesh

    2016-09-25

    We report the first example of Cu(I)-catalysed coupling of alkylboron reagents with aryl and heteroaryl iodides that affords products in good to excellent yields. Preliminary mechanistic studies with alkylborates indicate that the anionic (alkoxy)(alkyl)borates, generated from alkyllithium and alkoxyboron reagents, undergo disproportionation to anionic dialkylborates and that both anionic alkylborates are active for transmetalation to a Cu(I)-catalyst. Results from a radical clock experiment and the Hammett plot imply that the reaction likely proceeds via a non-radical pathway.

  8. The Influence of Active Transport Systems on Morphine -6-Glucuronide Transport in MDCKII and MDCK-PGP Cells

    Directory of Open Access Journals (Sweden)

    SO. Mashayekhi

    2011-12-01

    Full Text Available Background and the purpose of the study: Morphine-6-glucuronide (M6G is a potent metabolite of morphine which has high penetration into the brain despite its high polarity, which could be the result of an active transport system involved in M6G transport through blood brain barrier. Examples of such transporters are p-glycoprotein (PGP, probenecid-sensitive transport mechanism, multidrug resistance related protein 1-3, the organic anion transporter family, and the organic anion transporter polypeptide family. The aim of present study was to elucidate the mechanisms involved in transporting morphine's potent metabolite, M6G.Methods: M6G permeability via two cell lines; MDCKII and MDCK-PGP, was compared with that of sucrose. M6G transport was examined in different concentrations and in the presence of inhibitors of different transport systems such as cyclosporine, digoxin and probenecid. M6G concentration was measured using ELISA assay. The method was sensitive, reliable and reproducible.Results: The results confirmed that M6G could cross a layer of MDCK II or MDR-PGP cells more than sucrose could. It was also observed that M6G is a PGP transporter substrate. Its permeability was increased by the use of a PGP expressed cell line, and also in the presence of a strong PGP inhibitor. Digoxin related transporters such as Oatp2 may also involved in transport of M6G. M6G seemed to be a glucose transporter 1 substrate, but was not a substrate to probenecid sensitive transporters.Major conclusion: It is concluded that different transporters are responsible for M6G transports via different membrane, which could have effects on its pharmacokinetics or pharmacodynamics.

  9. Primary and secondary thyroid hormone transporters

    Directory of Open Access Journals (Sweden)

    Kinne Anita

    2011-08-01

    Full Text Available Abstract Thyroid hormones (TH are essential for the development of the human brain, growth and cellular metabolism. Investigation of TH transporters became one of the emerging fields in thyroid research after the discovery of inactivating mutations in the Monocarboxylate transporter 8 (MCT8, which was found to be highly specific for TH transport. However, additional transmembrane transporters are also very important for TH uptake and efflux in different cell types. They transport TH as secondary substrates and include the aromatic amino acid transporting MCT10, the organic anion transporting polypeptides (e.g. OATP1C1, OATP1A2, OPTP1A4 and the large neutral amino acid transporters (LAT1 and LAT2. These TH transporters characteristically possess 12 transmembrane spanners but due to the strong differing sequences between the three transporter families we assume an identical conformation is not very likely. In contrast to the others, the LAT family members form a heterodimer with the escort protein 4F2hc/CD98. A comparison of sequence proportions, locations and types of functional sensitive features for TH transport discovered by mutations, revealed that transport sensitive charged residues occur as conserved amino acids only within each family of the transporter types but not in all putative TH transporters. Based on the lack of highly conserved sensitive charged residues throughout the three transporter families as a common counterpart for the amino acid moiety of the substrates, we conclude that the molecular transport mechanism is likely organized either a by different molecular determinants in the divergent transporter types or b the counterparts for the substrates` amino acid moiety at the transporter are not any charged side chains but other proton acceptors or donators. However, positions of transport sensitive residues coincide at transmembrane helix 8 in the TH transporter MCT8, OATP1C1 and another amino acid transporter, the L

  10. Neurotransmitter transporters

    DEFF Research Database (Denmark)

    Gether, Ulrik; Andersen, Peter H; Larsson, Orla M

    2006-01-01

    The concentration of neurotransmitters in the extracellular space is tightly controlled by distinct classes of membrane transport proteins. This review focuses on the molecular function of two major classes of neurotransmitter transporter that are present in the cell membrane of neurons and....../or glial cells: the solute carrier (SLC)1 transporter family, which includes the transporters that mediate the Na(+)-dependent uptake of glutamate, and the SLC6 transporter family, which includes the transporters that mediate the Na(+)-dependent uptake of dopamine, 5-HT, norepinephrine, glycine and GABA....... Recent research has provided substantial insight into the structure and function of these transporters. In particular, the recent crystallizations of bacterial homologs are of the utmost importance, enabling the first reliable structural models of the mammalian neurotransmitter transporters...

  11. The serum anion gap is altered in early kidney disease and associates with mortality

    Science.gov (United States)

    Abramowitz, Matthew K.; Hostetter, Thomas H.; Melamed, Michal L.

    2012-01-01

    It is well known that uremia causes an increase in the serum anion gap; however, whether changes in the anion gap occur earlier in the course of chronic kidney disease is not known. Here we investigated whether different measures of the anion gap, as a marker of kidney function, are associated with mortality. To do this we analyzed the available laboratory data of 11,957 adults in the National Health and Nutrition Examination Survey 1999–2004 to calculate anion gap using the traditional method, or one that was albumin-adjusted, as well as a full anion gap reflecting other electrolytes. A significant elevation in the traditional anion gap was seen only with an estimated glomerular filtration rate (eGFR) less than 45 mL/min/1.73m2, whereas increases in the albumin-adjusted and full anion gap were found with eGFRs less than 60 or 90mL/min/1.73m2, respectively. Higher levels of each anion gap were associated with an increased risk of all-cause mortality after adjustment for age, gender, race/ethnicity, and eGFR. After adjustment for additional covariates including body-mass index and comorbidities, higher levels of the albumin-adjusted and full anion gap were associated with mortality (relative hazard for highest compared to the lowest quartile were 1.62 and 1.64, respectively). Thus, higher levels of anion gap are present in individuals with less advanced kidney disease than previously recognized, and are associated with increased risk of mortality. Further study is needed to identify the unmeasured anions and to determine their physiologic significance. PMID:22622500

  12. Monocarbaborane anion chemistry. The elusive C-arylated [PhCB11H11](-), [PhCB9H9]- and [PhCB8H8](-) anions

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Tomáš; Kilner, C. A.; Thornton-Pett, M.; Kennedy, J. D.

    č. 18 (2001), s. 1790-1791 ISSN 1359-7345 Institutional research plan: CEZ:AV0Z4032918 Keywords : weakly coordinating anions * carboranes Subject RIV: CA - Inorganic Chemistry Impact factor: 3.902, year: 2001

  13. Anionic and zwitterionic copper(I) complexes incorporating an anionic N-heterocyclic carbene decorated with a malonate backbone: synthesis, structure and catalytic applications.

    Science.gov (United States)

    César, Vincent; Barthes, Cécile; Farré, Yoann C; Cuisiat, Stéphane V; Vacher, Bernard Y; Brousses, Rémy; Lugan, Noël; Lavigne, Guy

    2013-05-28

    The anionic malonate-derived N-heterocyclic carbenes (maloNHCs) react cleanly and rapidly with copper chloride to generate the anionic complexes of type [(maloNHC)CuCl]·Li, which crystallize in the solid state either in an oligomeric trimer arrangement or in polymeric helixes depending on the substitution pattern and the solvent. Ten zwitterionic heteroleptic Cu(I) complexes combining the anionic maloNHC and a neutral imidazol-2-ylidene are also obtained in a very selective manner and fully characterized. Whereas the anionic complexes are relatively active catalysts for the hydrosilylation of carbonyl compounds, the zwitterionic complexes reveal to be efficient and extremely robust pre-catalysts for the intramolecular cyclopropanation reaction of a diazo ester and outperform the corresponding cationic Cu(i) complexes with classical imidazol-2-ylidenes.

  14. Palm oil anionic surfactants based emulsion breaker (Case study of emulsions breaker at Semanggi Field production wells)

    Science.gov (United States)

    Muhpidah; Hambali, E.; Suryani, A.; Kartika, I. A.

    2017-05-01

    The presence of emulsion in oil production process is undesirable. The emulsion will increase the production costs, transportation and costs related to emulsion separation process between water and oil. The development of palm oil-based surfactant as an emulsion breaker needs to be conducted given the availability of abundant raw materials in Indonesia and as an alternative to petroleum-based surfactant. The purpose of this study is to produce palm oil-based emulsion breaker, assessing the effect of additive application to the emulsion breaker and analyze the performance of the emulsion breaker. This research was conducted by formulating palm oil anionic surfactant in water formation with the addition of co-surfactant additive and co-solvent. Palm oil anionic surfactant-based emulsion breaker with 0.5% concentration in water can reduce 50% of emulsions with the interfacial tension (IFT) of 2.33x10-2 dyne/cm. The addition of co-solvent (toluene: xylene) is able to remove the emulsion formed with a lower IFT namely 10-3 dyne / cm. The resulting emulsion breaker is capable to remove the emulsion between water and oil. The performance test of emulsion breaker show that the emulsion is able to maintain its performance at reservoir temperature with no indicate of plugging and the value generated incremental oil recovery values is 13%.

  15. Mitochondrial membrane cholesterol, the voltage dependent anion channel (VDAC), and the Warburg effect.

    Science.gov (United States)

    Campbell, Andrew M; Chan, Samuel H P

    2008-06-01

    Normal cells of aerobic organisms synthesize the energy they require in the form of ATP via the process of oxidative phosphorylation. This complex system resides in the mitochondria of cells and utilizes oxygen to produce a majority of cellular ATP. However, in most tumors, especially those with elevated cholesterogenesis, there is an increased reliance on glycolysis for energy, even in conditions where oxygen is available. This aerobic glycolysis (the Warburg effect) has far reaching ramifications on the tumor itself and the cells that surround it. In this brief review, we will discuss how abnormally high membrane cholesterol levels can result in a subsequent deficiency of oxidative energy production in mitochondria from cultured Morris hepatoma cells (MH-7777). We have identified the voltage dependent anion channel (VDAC) as a necessary component of a protein complex involved in mitochondrial membrane cholesterol distribution and transport. Work in our laboratory demonstrates that the ability of VDAC to influence mitochondrial membrane cholesterol distribution may have implications on mitochondrial characteristics such as oxidative phosphorylation and induction of apoptosis, as well as the propensity of cancer cells to exhibit a glycolytic phenotype.

  16. Probing phosphoric acid redistribution and anion migration in polybenzimidazole membranes

    DEFF Research Database (Denmark)

    Becker, Hans; Cleemann, Lars Nilausen; Aili, David

    2017-01-01

    Micro platinum electrodes embedded in a laminated phosphoric acid doped polybenzimidazole membrane are employed to monitor the acid migration during hydrogen pump mode operation. Upon application of a constant current, an immediate ohmic resistance decrease of the membrane near the anode is obser......Micro platinum electrodes embedded in a laminated phosphoric acid doped polybenzimidazole membrane are employed to monitor the acid migration during hydrogen pump mode operation. Upon application of a constant current, an immediate ohmic resistance decrease of the membrane near the anode...... mechanism e.g. for determination of the anionic transference number. The finding provides a technique to monitor the acid redistribution within the membrane as a basis for an engineering solution to address the long-term durability of fuel cells built around phosphoric acid doped polymer membranes....

  17. Using solvent extraction to process nitrate anion exchange column effluents

    International Nuclear Information System (INIS)

    Yarbro, S.L.

    1987-10-01

    Octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO), a new organophosphorous extractant, and a new centrifugal mixer-settler both recently developed at Argonne were evaluated for their potential use in the recovery of actinides from nitrate anion exchange column effluents. The performance of the extractant was evaluated by measuring the extraction coefficient values as a function of acid and salt concentration. Additional performance parameters include extraction coefficient behavior as a function of the total metal concentration in the organic phase, and comparison of different stripping and organic scrubbing techniques. A simulated effluent stream was used to evaluate the performance of the centrifugal mixer-settlers by comparing experimental and calculated interstage concentration profiles. Both the CMPO extractant and the centrifugal mixer-settlers have potential for processing nitrate column effluents, particularly if the stripping behavior can be improved. Details of the proposed process are presented in the flowsheet and contactor design analyses

  18. Using solvent extraction to process nitrate anion exchange column effluents

    Energy Technology Data Exchange (ETDEWEB)

    Yarbro, S.L.

    1987-10-01

    Octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO), a new organophosphorous extractant, and a new centrifugal mixer-settler both recently developed at Argonne were evaluated for their potential use in the recovery of actinides from nitrate anion exchange column effluents. The performance of the extractant was evaluated by measuring the extraction coefficient values as a function of acid and salt concentration. Additional performance parameters include extraction coefficient behavior as a function of the total metal concentration in the organic phase, and comparison of different stripping and organic scrubbing techniques. A simulated effluent stream was used to evaluate the performance of the centrifugal mixer-settlers by comparing experimental and calculated interstage concentration profiles. Both the CMPO extractant and the centrifugal mixer-settlers have potential for processing nitrate column effluents, particularly if the stripping behavior can be improved. Details of the proposed process are presented in the flowsheet and contactor design analyses.

  19. Highly durable direct hydrazine hydrate anion exchange membrane fuel cell

    Science.gov (United States)

    Sakamoto, Tomokazu; Serov, Alexey; Masuda, Teruyuki; Kamakura, Masaki; Yoshimoto, Koji; Omata, Takuya; Kishi, Hirofumi; Yamaguchi, Susumu; Hori, Akihiro; Horiuchi, Yousuke; Terada, Tomoaki; Artyushkova, Kateryna; Atanassov, Plamen; Tanaka, Hirohisa

    2018-01-01

    The factors influenced on degradation of direct hydrazine hydrate fuel cells (DHFCs) under operation conditions are analyzed by in situ soft X-ray radiography. A durability of DHFCs is significantly improved by multi-step reaction DHFCs (MSR-DHFCs) approach designed to decrease the crossover of liquid fuel. An open circuit voltage (OCV) as well as cell voltage at 5 mA cm-2 of MSR-DHFC construct with commercial anion exchange membrane (AEM) maintained for over of 3500 h at 60 °C. Furthermore, the commercial proton exchange membrane (PEM) is integrated into AEM of MSR-DHFCs resulting in stable power output of MSR-DHFCs for over than 2800 h at 80 °C.

  20. Anion-exchange resin-based desulfurization process

    Energy Technology Data Exchange (ETDEWEB)

    Sheth, A.C.; Strevel, S.D.

    1991-01-01

    The University of Tennessee Space Institute (UTSI) has a Department of Energy grant to further develop the Institute's anion-exchange resin-based flue gas, desulfurization concept. The developmental program proposed includes screening of commercially available resins to select three candidate resins for further study. These three resins will undergo a series of experiments designed to test the resins' performance under different process conditions (including the use of spent MHD seed material). The best of these resins will be used in optimizing the regeneration step and in testing the effects of performance enhancers. The process schematic developed from the results will be used to estimate the related economics.

  1. Preliminary Testing For Anionic, Cationic and Non-ionic

    Directory of Open Access Journals (Sweden)

    Bokic, Lj.

    2007-11-01

    Full Text Available Detergents present a major environmental problem due to large quantities of surfactants released from laundries. For this reason, it is important to apply an appropriate analytical method for their determination. In this work, we propose two simple, fast and inexpensive analytical methods for anionic, cationic and non-ionic surfactant determination: thin layer chromatography (TLC separation for qualitative screening and quantitative potentiometric determination with ion-selective electrodes. These methods have been chosen because of their many advantages: rapidity, ease of operation, low cost of analysis and a wide variety of TLC application possibilities. The advantage of potentiometric titration is its very high degree of automation and very low detection limits obtained with different ion-selective electrodes applied for different surfactants.

  2. Quenching of p-cyanophenylalanine fluorescence by various anions

    Science.gov (United States)

    Pazos, Ileana M.; Roesch, Rachel M.; Gai, Feng

    2013-03-01

    To expand the spectroscopic utility of the non-natural amino acid p-cyanophenylalanine (PheCN), we examine the quenching efficiencies of a series of commonly encountered anions toward its fluorescence. We find that iodide exhibits an unusually large Stern-Volmer quenching constant, making it a convenient choice in PheCN fluorescence quenching studies. Indeed, using the villin headpiece subdomain as a testbed we demonstrate that iodide quenching of PheCN fluorescence offers a convenient means to reveal protein conformational heterogeneity. Furthermore, we show that the amino group of PheCN strongly quenches its fluorescence, suggesting that PheCN could be used as a local pH sensor.

  3. Partial molar volume of anionic polyelectrolytes in aqueous solution.

    Science.gov (United States)

    Salamanca, Constain; Contreras, Martín; Gamboa, Consuelo

    2007-05-15

    In this work the partial molar volumes (V) of different anionic polyelectrolytes and hydrophobically modified polyelectrolytes (PHM) were measured. Polymers like polymaleic acid-co-styrene, polymaleic acid-co-1-olefin, polymaleic acid-co-vinyl-2-pyrrolidone, and polyacrylic acid (abbreviated as MAS-n, PA-n-K2, AMVP, and PAA, respectively) were employed. These materials were investigated by density measurements in highly dilute aqueous solutions. The molar volume results allow us to discuss the effect of the carboxylic groups and the contributions from the comonomeric principal chain. The PAA presents the smaller V, while the largest V value was for AMVP. The V of PHM shows a linear relationship with the number of methylene groups in the lateral chain. It is found that the magnitude of the contribution per methylene group decreases as the hydrophobic character of the environment increases.

  4. IR spectroscopy of gaseous fluorocarbon ions: The perfluoroethyl anion

    Energy Technology Data Exchange (ETDEWEB)

    Crestoni, Maria Elisa; Chiavarino, Barbara [Dipartimento di Chimica e Tecnologie del Farmaco, Universita di Roma ' La Sapienza' , P. le A. Moro 5, I-00185 Roma (Italy); Lemaire, Joel; Maitre, Philippe [Universite Paris Sud, Laboratoire de Chimie Physique - UMR8000 CNRS, Faculte des Sciences - Batiment 350, 91405 Orsay Cedex (France); Fornarini, Simonetta, E-mail: simonetta.fornarini@uniroma1.it [Dipartimento di Chimica e Tecnologie del Farmaco, Universita di Roma ' La Sapienza' , P. le A. Moro 5, I-00185 Roma (Italy)

    2012-04-04

    Highlights: Black-Right-Pointing-Pointer C{sub 2}F{sub 5}{sup -} ions are formed by dissociative electron capture in perfluoropropane. Black-Right-Pointing-Pointer Both their reactivity towards neutrals and IRMPD spectroscopy are investigated. Black-Right-Pointing-Pointer The sampled C{sub 2}F{sub 5}{sup -} ions are best described as covalently bound pentafluoroethyl anions. - Abstract: The first IR spectrum of a perfluorinated carbanion has been obtained in the gas phase by IRMPD spectroscopy. Quantum chemical calculations at the MP2/cc-pVTZ level were performed yielding the optimized geometries and IR spectra for a covalently bound C{sub 2}F{sub 5}{sup -} species and for conceivable loosely bound F{sup -}(C{sub 2}F{sub 4}) complexes. Both the computational results and the IR characterization point to a covalent structure for the assayed species in agreement with the reactivity pattern displayed with selected neutrals.

  5. Reactivity of amino acid anions with nitrogen and oxygen atoms.

    Science.gov (United States)

    Wang, Zhe-Chen; Li, Ya-Ke; He, Sheng-Gui; Bierbaum, Veronica M

    2018-02-14

    For many decades, astronomers have searched for biological molecules, including amino acids, in the interstellar medium; this endeavor is important for investigating the hypothesis of the origin of life from space. The space environment is complex and atomic species, such as nitrogen and oxygen atoms, are widely distributed. In this work, the reactions of eight typical deprotonated amino acids (glycine, alanine, cysteine, proline, aspartic acid, histidine, tyrosine, and tryptophan) with ground state nitrogen and oxygen atoms are studied by experiment and theory. These amino acid anions do not react with nitrogen atoms. However, the reactions of these ions with oxygen atoms show an intriguing variety of ionic products and the reaction rate constants are of the order of 10 -10 cm 3 s -1 . Density functional calculations provide detailed mechanisms of the reactions, and demonstrate that spin conversion is essential for some processes. Our study provides important data and insights for understanding the kinetic and dynamic behavior of amino acids in space environments.

  6. UNCERTAINTIES OF ANION AND TOC MEASUREMENTS AT THE DWPF LABORATORY

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, T.

    2011-04-07

    The Savannah River Remediation (SRR) Defense Waste Processing Facility (DWPF) has identified a technical issue related to the amount of antifoam added to the Chemical Process Cell (CPC). Specifically, due to the long duration of the concentration and reflux cycles for the Sludge Receipt and Adjustment Tank (SRAT), additional antifoam has been required. The additional antifoam has been found to impact the melter flammability analysis as an additional source of carbon and hydrogen. To better understand and control the carbon and hydrogen contributors to the melter flammability analysis, SRR's Waste Solidification Engineering (WSE) has requested, via a Technical Task Request (TTR), that the Savannah River National Laboratory (SRNL) conduct an error evaluation of the measurements of key Slurry Mix Evaporator (SME) anions. SRNL issued a Task Technical and Quality Assurance Plan (TTQAP) [2] in response to that request, and the work reported here was conducted under the auspices of that TTQAP. The TTR instructs SRNL to conduct an error evaluation of anion measurements generated by the DWPF Laboratory using Ion Chromatography (IC) performed on SME samples. The anions of interest include nitrate, oxalate, and formate. Recent measurements of SME samples for these anions as well as measurements of total organic carbon (TOC) were provided to SRNL by DWPF Laboratory Operations (Lab OPS) personnel for this evaluation. This work was closely coordinated with the efforts of others within SRNL that are investigating the Chemical Process Cell (CPC) contributions to the melter flammability. The objective of that investigation was to develop a more comprehensive melter flammability control strategy that when implemented in DWPF will rely on process measurements. Accounting for the uncertainty of the measurements is necessary for successful implementation. The error evaluations conducted as part of this task will facilitate the integration of appropriate uncertainties for the

  7. Common, yet elusive: a case of severe anion gap acidosis.

    Science.gov (United States)

    Agrawal, Akanksha; Kishlyansky, Marina; Biso, Sylvia; Patnaik, Soumya; Punjabi, Chitra

    2017-09-01

    Acid-base disturbances are common occurrence in hospitalized patients with life threatening complications. 5-oxoproline has been increasingly recognized as cause of high anion gap metabolic acidosis (AGMA) in association with chronic acetaminophen use. However, laboratory workup for it are not widely available. We report case of 56-year-old female with severe AGMA not attributable to ketoacidosis, lactic acidosis or toxic ingestion. History was significant for chronic acetaminophen use, and laboratory workup negative for all frequent causes of AGMA. Given history and clinical presentation, our suspicion for 5-oxoproline toxicity was high. Our patient required emergent hemodialysis and subsequently improved clinically. With an increasing awareness of the uncommon causes of high AGMA, tests should be more readily available to detect their presence. Physicians should be more vigilant of underdiagnosed causes of AGMA if the presentation and laboratory values do not reflect a common cause, as definitive treatment may vary based on the offending agent.

  8. Speciation and transport of radionuclides in ground water

    International Nuclear Information System (INIS)

    Robertson, D.E.; Toste, A.P.; Abel, K.H.; Cowan, C.E.; Jenne, E.A.; Thomas, C.W.

    1984-01-01

    Studies of the chemical speciation of a number of radionuclides migrating in a slightly contaminated ground water plume are identifying the most mobile species and providing an opportunity to test and/or validate geochemical models of radionuclide transport in ground waters. Results to date have shown that most of the migrating radionuclides are present in anionic or nonionic forms. These include anionic forms of 55 Fe, 60 Co, /sup 99m/Tc, 106 Ru, 131 I, and nonionic forms of 63 Ni and 125 Sb. Strontium-70 and a small fraction of the mobile 60 Co are the only cationic radionuclides which have been detected moving in the ground water plume beyond 30 meters from the source. A comparison of the observed chemical forms with the predicted species calculated from modeling thermodynamic data and ground water chemical parameters has indicated a good agreement for most of the radioelements in the system, including Tc, Np, Cs, Sr, Ce, Ru, Sb, Zn, and Mn. The discrepancies between observed and calculated solutions species were noted for Fe, Co, Ni and I. Traces of Fe, Co, and Ni were observed to migrate in anionic or nonionic forms which the calculations failed to predict. These anionic/nonionic species may be organic complexes having enhanced mobility in ground waters. The radioiodine, for example, was shown to behave totally as an anion but further investigation revealed that 49-57% of this anionic iodine was organically bound. The ground water and aqueous extracts of trench sediments contain a wide variety of organic compounds, some of which could serve as complexing agents for the radionuclides. These results indicate the need for further research at a variety of field sites in defining precisely the chemical forms of the mobile radionuclide species, and in better understanding the role of dissolved organic materials in ground water transport of radionuclides

  9. Enhanced DOC removal using anion and cation ion exchange resins.

    Science.gov (United States)

    Arias-Paic, Miguel; Cawley, Kaelin M; Byg, Steve; Rosario-Ortiz, Fernando L

    2016-01-01

    Hardness and DOC removal in a single ion exchange unit operation allows for less infrastructure, is advantageous for process operation and depending on the water source, could enhance anion exchange resin removal of dissolved organic carbon (DOC). Simultaneous application of cationic (Plus) and anionic (MIEX) ion exchange resin in a single contact vessel was tested at pilot and bench scales, under multiple regeneration cycles. Hardness removal correlated with theoretical predictions; where measured hardness was between 88 and 98% of the predicted value. Comparing bench scale DOC removal of solely treating water with MIEX compared to Plus and MIEX treated water showed an enhanced DOC removal, where removal was increased from 0.5 to 1.25 mg/L for the simultaneous resin application compared to solely applying MIEX resin. A full scale MIEX treatment plant (14.5 MGD) reduced raw water DOC from 13.7 mg/L to 4.90 mg/L in the treated effluent at a bed volume (BV) treatment rate of 800, where a parallel operation of a simultaneous MIEX and Plus resin pilot (10 gpm) measured effluent DOC concentrations of no greater than 3.4 mg/L, even at bed volumes of treatment 37.5% greater than the full scale plant. MIEX effluent compared to simultaneous Plus and MIEX effluent resulted in differences in fluorescence intensity that correlated to decreases in DOC concentration. The simultaneous treatment of Plus and MIEX resin produced water with predominantly microbial character, indicating the enhanced DOC removal was principally due to increased removal of terrestrially derived organic matter. The addition of Plus resin to a process train with MIEX resin allows for one treatment process to remove both DOC and hardness, where a single brine waste stream can be sent to sewer at a full-scale plant, completely removing lime chemical addition and sludge waste disposal for precipitative softening processes. Published by Elsevier Ltd.

  10. Noncompetitive, Voltage-Dependent NMDA Receptor Antagonism by Hydrophobic Anions

    Science.gov (United States)

    Linsenbardt, Andrew J.; Chisari, Mariangela; Yu, Andrew; Shu, Hong-Jin; Zorumski, Charles F.

    2013-01-01

    NMDA receptor (NMDAR) antagonists are dissociative anesthetics, drugs of abuse, and are of therapeutic interest in neurodegeneration and neuropsychiatric disease. Many well-known NMDAR antagonists are positively charged, voltage-dependent channel blockers. We recently showed that the hydrophobic anion dipicrylamine (DPA) negatively regulates GABAA receptor function by a mechanism indistinguishable from that of sulfated neurosteroids. Because sulfated neurosteroids also modulate NMDARs, here we examined the effects of DPA on NMDAR function. In rat hippocampal neurons DPA inhibited currents gated by 300 µM NMDA with an IC50 of 2.3 µM. Neither onset nor offset of antagonism exhibited dependence on channel activation but exhibited a noncompetitive profile. DPA antagonism was independent of NMDAR subunit composition and was similar at extrasynaptic and total receptor populations. Surprisingly, similar to cationic channel blockers but unlike sulfated neurosteroids, DPA antagonism was voltage dependent. Onset and offset of DPA antagonism were nearly 10-fold faster than DPA-induced increases in membrane capacitance, suggesting that membrane interactions do not directly explain antagonism. Furthermore, voltage dependence did not derive from association of DPA with a site on NMDARs directly accessible to the outer membrane leaflet, assessed by DPA translocation experiments. Consistent with the expected lack of channel block, DPA antagonism did not interact with permeant ions. Therefore, we speculate that voltage dependence may arise from interactions of DPA with the inherent voltage dependence of channel gating. Overall, we conclude that DPA noncompetitively inhibits NMDA-induced current by a novel voltage-dependent mechanism and represents a new class of anionic NMDAR antagonists. PMID:23144238

  11. Interactions of Phospholipid Vesicles with Cationic and Anionic Oligomeric Surfactants.

    Science.gov (United States)

    Chen, Yao; Qiao, Fulin; Fan, Yaxun; Han, Yuchun; Wang, Yilin

    2017-07-27

    This work studied the interactions of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) with cationic ammonium surfactants and anionic sulfate or sulfonate surfactants of different oligomeric degrees, including cationic monomeric DTAB, dimeric C 12 C 3 C 12 Br 2 , and trimeric DDAD as well as anionic monomeric SDS, dimeric C 12 C 3 C 12 (SO 3 ) 2 , and trimeric TED-(C 10 SO 3 Na) 3 . The partition coefficient P of these surfactants between the DOPC vesicles and water was determined with isothermal titration microcalorimetry (ITC) by titrating concentrated DOPC solution into the monomer solution of these surfactants. It was found that the P value increases with the increase of the surfactant oligomeric degree. Moreover, the enthalpy change and the Gibbs free energy for the transition of these surfactants from water into the DOPC bilayer become more negative with increasing the oligomeric degree. Meanwhile, the calcein release experiment proves that the surfactant with a higher oligomeric degree shows stronger ability of changing the permeability of the DOPC vesicles. Furthermore, the solubilization of the DOPC vesicles by these oligomeric surfactants was studied by ITC, turbidity, and dynamic light scattering, and thus the phase boundaries for the surfactant/lipid mixtures have been determined. The critical surfactant to lipid ratios for the onset and end of the solubilization for the DOPC vesicles derived from the phase boundaries decrease remarkably with increasing the oligomeric degree. Overall, the surfactant with a larger oligomerization degree shows stronger ability in incorporating into the lipid bilayer, altering the membrane permeability and solubilizing lipid vesicles, which provides comprehensive understanding about the effects of structure and shape of oligomeric surfactant molecules on lipid-surfactant interactions.

  12. Photochemical reaction cycle transitions during anion channelrhodopsin gating.

    Science.gov (United States)

    Sineshchekov, Oleg A; Li, Hai; Govorunova, Elena G; Spudich, John L

    2016-04-05

    A recently discovered family of natural anion channelrhodopsins (ACRs) have the highest conductance among channelrhodopsins and exhibit exclusive anion selectivity, which make them efficient inhibitory tools for optogenetics. We report analysis of flash-induced absorption changes in purified wild-type and mutant ACRs, and of photocurrents they generate in HEK293 cells. Contrary to cation channelrhodopsins (CCRs), the ion conducting state of ACRs develops in an L-like intermediate that precedes the deprotonation of the retinylidene Schiff base (i.e., formation of an M intermediate). Channel closing involves two mechanisms leading to depletion of the conducting L-like state: (i) Fast closing is caused by a reversible L⇔M conversion. Glu-68 in Guillardia theta ACR1 plays an important role in this transition, likely serving as a counterion and proton acceptor at least at high and neutral pH. Incomplete suppression of M formation in the GtACR1_E68Q mutant indicates the existence of an alternative proton acceptor. (ii) Slow closing of the channel parallels irreversible depletion of the M-like and, hence, L-like state. Mutation of Cys-102 that strongly affected slow channel closing slowed the photocycle to the same extent. The L and M intermediates were in equilibrium in C102A as in the WT. In the position of Glu-123 in channelrhodopsin-2, ACRs contain a noncarboxylate residue, the mutation of which to Glu produced early Schiff base proton transfer and strongly inhibited channel activity. The data reveal fundamental differences between natural ACR and CCR conductance mechanisms and their underlying photochemistry, further confirming that these proteins form distinct families of rhodopsin channels.

  13. Probing electron density of H-bonding between cation-anion of imidazolium-based ionic liquids with different anions by vibrational spectroscopy.

    Science.gov (United States)

    Gao, Yan; Zhang, Liqun; Wang, Yong; Li, Haoran

    2010-03-04

    Attenuated total reflection infrared spectroscopy and density functional theory calculation have been employed to study the spectral properties of imidazolium-based ionic liquids (ILs) with different anions. ILs based on 1-butyl-3-methylimidazolium cation with different anions, OH(-), CF(3)CO(2)(-), HSO(4)(-), H(2)PO(4)(-), Cl(-), PF(6)(-), and BF(4)(-), are investigated in the present work. It has been shown that the C(2)-H stretching vibration of the imidazolium ring is closely related to the electron density of H-bonding between the two closest cations and anions for pure ILs. The electron density of H-bonding between cation and anion with different anions decreases in the order [OH](-) > [H(2)PO(4)](-) > [HSO(4)](-) > [CF(3)CO(2)](-) > [Cl](-) > [BF(4)](-) > [PF(6)](-). For aqueous ILs, with increasing water content, the aromatic C-H stretching vibration of the imidazolium cation showed systematic blue-shifts. Especially for BmimOH, the nu(C(2))(-H) undergoes a drastic blue-shift by 58 cm(-1), suggesting that the formation of the strong hydrogen bonds O-H...O may greatly weaken the electron density of H-bonding between the cation and anion of ILs.

  14. The role of volume-sensitive ion transport systems in regulation of epithelial transport

    DEFF Research Database (Denmark)

    Hoffmann, Else Kay; Schettino, T; Marshall, W S

    2007-01-01

    This review focuses on using the knowledge on volume-sensitive transport systems in Ehrlich ascites tumour cells and NIH-3T3 cells to elucidate osmotic regulation of salt transport in epithelia. Using the intestine of the European eel (Anguilla anguilla) (an absorptive epithelium of the type...... described in the renal cortex thick ascending limb (cTAL)) we have focused on the role of swelling-activated K+- and anion-conductive pathways in response to hypotonicity, and on the role of the apical (luminal) Na+-K+-2Cl- cotransporter (NKCC2) in the response to hypertonicity. The shrinkage...

  15. Effect of Structure on Charge Distribution in the Isatin Anions in Aprotic Environment: Spectral Study

    Directory of Open Access Journals (Sweden)

    Pavol Tisovský

    2017-11-01

    Full Text Available Five isatin anions were prepared by deprotonation of initial isatins in aprotic solvents using basic fluoride and acetate anions (F− and CH3COO−. The F− basicity is sufficient to deprotonate isatin NH hydrogen from all the studied compounds. This process is reversible. In the presence of proton donor solvents, the anions form the corresponding isatins. The isatin hydrogen acidity depends on the overall structure of the isatin derivatives. The anions were characterized by ultraviolet–visible (UV–Vis, Fourier transform infrared (FTIR and nuclear magnetic resonance (NMR spectroscopy. Interestingly, the anions form aggregates at concentrations above 10−3 mol·dm−3. Further, the effect of cations on the UV–Vis spectra of the studied anions was studied. Charge transfer and its distribution in the anion depends on the radius and the cation electron configuration. The alkali metal cations, tetrabutylammonium (TBA+, Mg2+ and Ag+, interact with the C-2 carbonyl oxygen of the isatin anion. The interaction has a coulombic character. On the other hand, Cd2+, Zn2+, Hg2+, Co2+, and Cu+ cations form a coordinate bond with the isatin nitrogen.

  16. CO{sub 2} binding in the (quinoline-CO{sub 2}){sup −} anionic complex

    Energy Technology Data Exchange (ETDEWEB)

    Graham, Jacob D.; Buytendyk, Allyson M.; Wang, Yi; Bowen, Kit H., E-mail: kbowen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Kim, Seong K. [Department of Chemistry, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2015-06-21

    We have studied the (quinoline-CO{sub 2}){sup −} anionic complex by a combination of mass spectrometry, anion photoelectron spectroscopy, and density functional theory calculations. The (quinoline-CO{sub 2}){sup −} anionic complex has much in common with previously studied (N-heterocycle-CO{sub 2}){sup −} anionic complexes both in terms of geometric structure and covalent bonding character. Unlike the previously studied N-heterocycles, however, quinoline has a positive electron affinity, and this provided a pathway for determining the binding energy of CO{sub 2} in the (quinoline-CO{sub 2}){sup −} anionic complex. From the theoretical calculations, we found CO{sub 2} to be bound within the (quinoline-CO{sub 2}){sup −} anionic complex by 0.6 eV. We also showed that the excess electron is delocalized over the entire molecular framework. It is likely that the CO{sub 2} binding energies and excess electron delocalization profiles of the previously studied (N-heterocycle-CO{sub 2}){sup −} anionic complexes are quite similar to that of the (quinoline-CO{sub 2}){sup −} anionic complex. This class of complexes may have a role to play in CO{sub 2} activation and/or sequestration.

  17. use of weak ion association in the separation of inorganic anions by ...

    African Journals Online (AJOL)

    a

    ANIONS BY CAPILLARY ELECTROPHORESIS WITH SPECIFIC APPLICATION. TO SIMULTANEOUS-TRACE .... ions. CE compliments ion chromatography but is preferred in inorganic anions determination, because of its simplicity in method development, less wastage of reagents and high efficiency coupled with lower ...

  18. www.ajol.info and www.bioline.org.br/ja Evaluation of Serum Anion ...

    African Journals Online (AJOL)

    ADOWIE PERE

    gastrointestinal and renal system can alter the acid- base balance of the pregnant woman. This alteration ultimately affects the anion gap which is a function of the electrolytes; sodium, potassium, chloride and bicarbonate. The anion gap being a function of electrolytes can be affected by gastrointestinal symptoms such as.

  19. Superoxide anion-induced pain and inflammation depends on TNFα/TNFR1 signaling in mice.

    Science.gov (United States)

    Yamacita-Borin, Fabiane Y; Zarpelon, Ana C; Pinho-Ribeiro, Felipe A; Fattori, Victor; Alves-Filho, Jose C; Cunha, Fernando Q; Cunha, Thiago M; Casagrande, Rubia; Verri, Waldiceu A

    2015-09-25

    Inhibition of tumor necrosis factor-alpha (TNFα) and superoxide anion production reduces inflammation and pain. The present study investigated whether superoxide anion-induced pain depends on TNFα signaling and the role of superoxide anion in TNFα-induced hyperalgesia to clarify the interrelation between these two mediators in the context of pain. Intraplantar injection of a superoxide anion donor (potassium superoxide) induced mechanical hyperalgesia (0.5-5h after injection), neutrophil recruitment (myeloperoxidase activity), and overt pain-like behaviors (paw flinching, paw licking, and abdominal writhings) in wild-type mice. Tumor necrosis factor receptor 1 deficiency (TNFR1-/-) and treatment of wild-type mice with etanercept (a soluble TNFR2 receptor that inhibits TNFα actions) inhibited superoxide anion-induced pain-like behaviors. TNFR1(-/-) mice were also protected from superoxide anion donor-induced oxidative stress, suggesting the role of this pathway in the maintenance of oxidative stress. Finally, we demonstrated that Apocynin (an NADPH oxidase inhibitor) or Tempol (a superoxide dismutase mimetic) treatment inhibited TNFα-induced paw mechanical hyperalgesia and neutrophil recruitment (myeloperoxidase activity). These results demonstrate that TNFα/TNFR1 signaling is important in superoxide anion-triggered pain and that TNFα/TNFR1 signaling amplifies the oxidative stress triggered by superoxide anion, which contributes to sustaining pain and inflammation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  20. Specificity of anion-binding in the substrate-pocket ofbacteriorhodopsin

    Energy Technology Data Exchange (ETDEWEB)

    Facciotti, Marc T.; Cheung, Vincent S.; Lunde, Christopher S.; Rouhani, Shahab; Baliga, Nitin S.; Glaeser, Robert M.

    2003-08-30

    The structure of the D85S mutant of bacteriorhodopsin with a nitrate anion bound in the Schiff-base binding site, and the structure of the anion-free protein have been obtained in the same crystal form. Together with the previously solved structures of this anion pump, in both the anion-free state and bromide-bound state, these new structures provide insight into how this mutant of bacteriorhodopsin is able to bind a variety of different anions in the same binding pocket. The structural analysis reveals that the main structural change that accommodates different anions is the repositioning of the polar side-chain of S85. On the basis of these x-ray crystal structures, the prediction is then made that the D85S/D212N double mutant might bind similar anions and do so over a broader pH range than does the single mutant. Experimental comparison of the dissociation constants, K{sub d}, for a variety of anions confirms this prediction and demonstrates, in addition, that the binding affinity is dramatically improved by the D212N substitution.

  1. Anionic polymerization and polyhomologation: An ideal combination to synthesize polyethylene-based block copolymers

    KAUST Repository

    Zhang, H.

    2013-08-07

    A novel one-pot methodology combining anionic polymerization and polyhomologation, through a "bridge" molecule (BF3OEt 2), was developed for the synthesis of polyethylene (PE)-based block copolymers. The anionically synthesized macroanion reacts with the "bridge" molecule to afford a 3-arm star (trimacromolecular borane) which serves as an initiator for the polyhomologation. 2013 The Royal Society of Chemistry.

  2. Anion Gap as a Determinant of Ionized Fraction of Divalent Cations in Hemodialysis Patients.

    Science.gov (United States)

    Sakaguchi, Yusuke; Hamano, Takayuki; Kubota, Keiichi; Oka, Tatsufumi; Yamaguchi, Satoshi; Matsumoto, Ayumi; Hashimoto, Nobuhiro; Mori, Daisuke; Obi, Yasue; Matsui, Isao; Isaka, Yoshitaka

    2018-02-07

    Circulating levels of anions that bind to magnesium and calcium are often altered in patients with CKD. However, it is unknown how these alterations affect the ionized fraction of magnesium and calcium. This cross-sectional study involved patients on maintenance hemodialysis and patients not on dialysis who visited the outpatient department of nephrology. We collected whole-blood samples to measure ionized magnesium and calcium concentrations. Adjusted anion gap was calculated as an integrative index of unmeasured anions. A total of 118 patients on hemodialysis and 112 patients not on dialysis were included. Although the prevalence of hypermagnesemia defined by total magnesium was much higher in patients on hemodialysis than in patients not on dialysis (69% versus 12%; P anion gap than patients not on dialysis (mean [SD]: 14.1 [2.2] versus 5.1 [3.1]), the ionized fractions of magnesium and calcium were inversely associated with the adjusted anion gap. Furthermore, the anion gap significantly improved predictions of ionized magnesium and calcium in patients on hemodialysis. Anions that accumulate in patients on hemodialysis contribute to the lower ionized fraction of magnesium and calcium. Equations that incorporate the anion gap provide better predictions of ionized magnesium and calcium in patients on hemodialysis. Copyright © 2018 by the American Society of Nephrology.

  3. [Serum anion gap in the umbilical cord blood of healthy newborn infants].

    Science.gov (United States)

    Jóźwik, Michał; Jóźwik, Marcin; Pietrzycki, Bartosz

    2002-01-01

    This paper presents the results of the determination of serum anion gap in arterial and venous umbilical cord blood obtained from a carefully selected group of 47 healthy term newborns. In the arterial blood, the following concentrations of particular anions were found: chloride - 102.85 +/- 4.35 mmol/l, bicarbonate - 22.26 +/- 2.67 mmol/l, protein anions - 11.89 +/- 1.00 mmol/l, and residual anions - 14.26 +/- 4.35 mmol/l, while in the venous blood these values were: chloride - 104.28 +/- 4.14 mmol/l, bicarbonate - 20.79 +/- 2.70 mmol/l, protein anions - 12.48 +/- 1.23 mmol/l, and residual anions - 13.03 +/- 3.06 mmol/l. Provided strict clinical and biochemical (acid-base balance and blood gases) selections criteria are applied, these data are likely to represent normal values for term newborns and can be the basis for comparison of umbilical serum anion gap in newborns under depressed conditions, like asphyxia. As discussed, the role of serum anion gap studies in the diagnosis of the type of metabolic acidosis, as well as in the monitoring of neonatal therapy is most important.

  4. The Anion Gap is a Predictive Clinical Marker for Death in Patients with Acute Pesticide Intoxication.

    Science.gov (United States)

    Lee, Sun-Hyo; Park, Samel; Lee, Jung-Won; Hwang, Il-Woong; Moon, Hyung-Jun; Kim, Ki-Hwan; Park, Su-Yeon; Gil, Hyo-Wook; Hong, Sae-Yong

    2016-07-01

    Pesticide formulation includes solvents (methanol and xylene) and antifreeze (ethylene glycol) whose metabolites are anions such as formic acid, hippuric acid, and oxalate. However, the effect of the anion gap on clinical outcome in acute pesticide intoxication requires clarification. In this prospective study, we compared the anion gap and other parameters between surviving versus deceased patients with acute pesticide intoxication. The following parameters were assessed in 1,058 patients with acute pesticide intoxication: blood chemistry (blood urea nitrogen, creatinine, glucose, lactic acid, liver enzymes, albumin, globulin, and urate), urinalysis (ketone bodies), arterial blood gas analysis, electrolytes (Na(+), K(+), Cl(-) HCO3 (-), Ca(++)), pesticide field of use, class, and ingestion amount, clinical outcome (death rate, length of hospital stay, length of intensive care unit stay, and seriousness of toxic symptoms), and the calculated anion gap. Among the 481 patients with a high anion gap, 52.2% had a blood pH in the physiologic range, 35.8% had metabolic acidosis, and 12.1% had acidemia. Age, anion gap, pesticide field of use, pesticide class, seriousness of symptoms (all P anion gap, and pesticide class were significant risk factors for death in a multiple logistic regression analysis (P anion gap is a significant risk factor for death, regardless of the accompanying acid-base balance status in patients with acute pesticide intoxication.

  5. Minding the Gap: Utility of the Anion Gap in the Differential Diagnosis of Metabolic Acidosis.

    Science.gov (United States)

    Bell, Susan Givens

    2017-07-01

    The anion gap, in conjunction with other laboratory results, can be a useful clue in the differential diagnosis of metabolic acidosis. There are three primary causes of metabolic acidosis: loss of base, decreased renal excretion of acid, and increased acid production. Depending on the cause of metabolic acidosis, the anion gap may be elevated or normal.

  6. Photocontrol of Anion Binding Affinity to a Bis-urea Receptor Derived from Stiff-Stilbene

    NARCIS (Netherlands)

    Wezenberg, Sander J.; Feringa, Ben L.

    2017-01-01

    Toward the development of photoresponsive anion receptors, a stiff-stilbene photoswitch has been equipped' with two urea anion -binding motifs. Photoinduced E/Z isomerization has been studied in detail by UV-vis and NMR spectroscopy. Titration experiments (H-1 NMR) reveal strong binding of acetate

  7. Rifampicin Induces Bicarbonate-Rich Choleresis in Rats: Involvement of Anion Exchanger 2.

    Science.gov (United States)

    Wang, Wei; Ren, Xiaofei; Cai, Yi; Chen, Lihong; Zhang, Weiping; Xu, Jianming

    2016-01-01

    Previous studies have shown that rifampicin induced choleresis, the mechanisms of which have not been described. The aim of this study was to investigate the mechanisms underlying in vivo rifampicin-induced choleresis. In one experimental set, rats were treated chronically with rifampicin on days 1, 3 and 7. Serum and biliary parameters were assayed, and mRNA and protein levels, as well as the locations of the hepatic export transporters were analyzed by real-time PCR, western blot and immunofluorescence. Ductular mass was evaluated immunohistochemically. In another experimental set, rats received an acute infusion of rifampicin. The amount of rifampicin in bile was detected using HPLC. Biliary parameters were monitored following intrabiliary retrograde fluxes of the Cl(-)/HCO3 (-) exchange inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) or 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) in the infused rats. Biliary bicarbonate output increased in parallel to the augmented bile flow in response to rifampicin, and this effect was abolished with intrabiliary administration of DIDS, but not NPPB. The biliary secretion of rifampicin with increases in bile flow and biliary rifampicin in response to different infused doses of the antibiotic show no significant correlations. After rifampicin treatment, the expression level of anion exchanger 2 (AE2) increased, while the location of hepatic transporters did not change. However, RIF treatment did not increase ductular mass significantly. These results indicate that the increase in bile flow induced by rifampicin is mainly due to increased HCO3 (-) excretion mediated by increased AE2 protein expression and activity.

  8. Anion capture with calcium, aluminium and iron containing layered double hydroxides

    Science.gov (United States)

    Phillips, J. D.; Vandeperre, L. J.

    2011-09-01

    The competitive adsorption of nitrate, chloride and carbonate in layered double hydroxides (LHD) with the general formula Ca(1-x)2+Al(1-y)3+,Fe(y)3+x(OH)2xNO3-·nHO was investigated. Both normal ion exchange by exposure to a solution containing different anions, as well as addition of calcined material to solution thereby exploiting the memory effect of LDHs was studied. Changes in the interlayer anion changed the interlayer spacing of the LDH. The order of preference of intercalation was Cl≈CO32->NO3-. When multiple anions were present in the exchange solution, LDHs with several distinct interlayer spacing were produced indicating that LDHs with different anions in the interlayer existed at the same time. However for extended exchange times (14 days) where high concentrations of carbonate anion were present, the layered structure was destroyed resulting in the formation of calcite, CaCO 3.

  9. Sorption of Pu(IV) from nitric acid by bifunctional anion-exchange resins

    International Nuclear Information System (INIS)

    Bartsch, R.A.; Zhang, Z.Y.; Elshani, S.; Zhao, W.; Jarvinen, G.D.; Barr, M.E.; Marsh, S.F.; Chamberlin, R.M.

    1999-01-01

    Anion exchange is attractive for separating plutonium because the Pu(IV) nitrate complex is very strongly sorbed and few other metal ions form competing anionic nitrate complexes. The major disadvantage of this process has been the unusually slow rate at which the Pu(IV) nitrate complex is sorbed by the resin. The paper summarizes the concept of bifunctional anion-exchange resins, proposed mechanism for Pu(IV) sorption, synthesis of the alkylating agent, calculation of K d values from Pu(IV) sorption results, and conclusions from the study of Pu(IV) sorption from 7M nitric acid by macroporous anion-exchange resins including level of crosslinking, level of alkylation, length of spacer, and bifunctional vs. monofunctional anion-exchange resins

  10. Physical Removal of Anions from Aqueous Media by Means of a Macrocycle-Containing Polymeric Network

    KAUST Repository

    Ji, Xiaofan

    2018-02-13

    Reported here is a hydrogel-forming polymer network that contains a water-soluble tetracationic macrocycle. Upon immersion of this polymer network in aqueous solutions containing various inorganic and organic salts, changes in the physical properties are observed that are consistent with absorption of the constituent anions into the polymer network. This absorption is ascribed to host-guest interactions involving the tetracationic macrocyclic receptor. Removal of the anions may then be achieved by lifting the resulting hydrogels out of the aqueous phase. Treating the anion-containing hydrogels with dilute HCl leads to the protonation-induced release of the bound anions. This allows the hydrogels to be recycled for reuse. The present polymer network thus provides a potentially attractive approach to removing undesired anions from aqueous environments.

  11. Determination of Anionic Detergent Concentration of Karasu Stream in Sinop (Turkey

    Directory of Open Access Journals (Sweden)

    Ayşe Gündoğdu

    2018-02-01

    Full Text Available The study was achieved between May 2014 and April 2015 at the Karasu Creek located in the province of Sinop. It was conducted to determine anionic detergent pollution and some physicochemical properties (pH, temperature, conductivity, salinity, dissolved oxygen, total hardness, chemical oxygen demand, phosphate PO4-3, total nitrogen. The anionic detergent concentration of the stations was determined on a monthly basis. Seasonally averaged values of the anionic detergent was measured as the highest value in the autumn season. The lowest values of anionic detergent were found in stations in winter and spring. The increase in the concentration of anionic detergent is caused by population growth in residential areas, increased agricultural activities and rains, and that chemicals move to riverbed from terrestrial areas with rain water.

  12. Do anionic titanium dioxide nano-clusters reach bulk band gap? A density functional theory study.

    Science.gov (United States)

    Qu, Zheng-Wang; Zhu, Hui

    2010-07-30

    The electronic properties of both neutral and anionic (TiO(2))(n) (n = 1-10) clusters are investigated by extensive density functional theory calculations. The predicted electron detachment energies and excitation gaps of anionic clusters agree well with the original experimental anion photoelectron spectra (APES). It is shown that the old way to analyze APES tends to overestimate vertical excitation gaps (VGA) of large anionic clusters, due to the nature of multiple electronic origins for the higher APES bands. Moreover, the VGA of anionic TiO(2) clusters are evidently smaller than those of neutral clusters, which may also be the case for other metal oxide clusters with high electron affinity. 2010 Wiley Periodicals, Inc.

  13. Ileal Neobladder: An Important Cause of Non-Anion Gap Metabolic Acidosis.

    Science.gov (United States)

    St Clair, Jesse W; Wong, Matthew L

    2017-05-01

    The differential diagnosis for a non-anion gap metabolic acidosis is probably less well known than the differential diagnosis for an anion gap metabolic acidosis. One etiology of a non-anion gap acidosis is the consequence of ileal neobladder urinary diversion for the treatment of bladder cancer. We present a case of a patient with an ileal neobladder with a severe non-anion gap metabolic acidosis caused by a urinary tract infection and ureteroenterostomy. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Part of the ileal neobladder surgery includes ureteroenterostomy and predisposes patients to several clinically significant metabolic derangements, including a non-anion gap metabolic acidosis. These patients have an increased chronic acid load, bicarbonate deficit, and hypokalemia, which should be appreciated when resuscitating these patients. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Aprotic Heterocyclic Anion Triazolide Ionic Liquids - A New Class of Ionic Liquid Anion Accessed by the Huisgen Cycloaddition Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Robert [National Energy Technology Laboratory; Damodaran, Krishnan [Department of Chemistry, University of Pittsburgh; Luebke, David [National Energy Technology Laboratory; Nulwala, Hunaid [National Energy Technology Laboratory

    2013-04-18

    The triazole core is a highly versatile heterocyclic ring which can be accessed easily with the Cu(I)-catalyzed Huisgen cycloaddition reaction. Herein we present the preparation of ionic liquids that incorporate a 1,2,3-triazolide anion. These ionic liquids were prepared by a facile procedure utilizing a base-labile pivaloylmethyl group at the 1-position, which can act as precursors to 1H- 4-substituted 1,2,3-triazole. These triazoles were then subsequently converted into ionic liquids after deprotonation using an appropriate ionic liquid cation hydroxide. The densities and thermal decompositions of these ionic liquids were measured. These novel ionic liquids have potential applications in gas separations and in metal-free catalysis.

  15. Development and characterization of direct ethanol fuel cells using alkaline anion-exchange membranes

    Science.gov (United States)

    Lim, Peck Cheng

    2009-08-01

    Alkaline membrane fuel cell (AMFC) is a relatively new fuel cell technology that is generating considerable interests. It offers the electrocatalytic advantages of conventional alkaline fuel cells, and the manufacturing and cost advantages of solid polymer electrolyte fuel cells. This project was carried out to develop and characterize high performance membrane electrode assemblies (MEAs) for all-solid-state AMFCs. The primary fuel of interests is ethanol, but hydrogen was used in the development stages to facilitate the diagnostic and evaluation of the fuel cell performance. In the preliminary investigation, AMFC was assembled using off-the-shelf electrodes and anion-exchange membrane (AEM). It was found that the performance of AMFC operating on ethanol fuel was limited by a large high-frequency resistance (HFR) value. The advantage of using non-toxic ethanol fuel was also compromised by the need to add hydrazine and potassium hydroxide to the fuel blend. Subsequently, a high performance MEA was developed for an all-solid-state AMFC, in which liquid electrolyte or other additives were not required during the operation of the fuel cell. Ionomer was incorporated in the formulation of catalyst ink, and the catalyst ink was directly coated on the anion-exchange membrane (AEM). An ionomer content of 20 wt.% was found to be the optimum amount required in the catalyst layers. It was demonstrated that the AMFC generated a maximum power density of 365 mW/cm2 and 213 mW/cm 2 with the use of hydrogen/oxygen and hydrogen/pure air, respectively. The performance of the AMFC was also found to be influenced by exposure to carbon dioxide in the air. Hence, the CCMs were pre-treated in potassium hydroxide solution and pure oxygen was used to condition the fuel cell to maximize the power output from the AMFCs. Although satisfactory performance was demonstrated in the AMFC, its stability during cell operation remains a major issue. The poor stability was attributed to degradation of

  16. Experimental evidence for interactions between anions and electron-deficient aromatic rings.

    Science.gov (United States)

    Berryman, Orion B; Johnson, Darren W

    2009-06-14

    This feature article summarizes our research aimed at using electron-deficient aromatic rings to bind anions in the context of complementary research in this active field. Particular attention is paid to the different types of interactions exhibited between anions and electron-deficient arenes in solution. The 120+ references cited in this article underscore the flurry of recent activity by numerous researchers in this field, which was relatively nascent when our efforts began in 2005. While the interaction of anions with electron-deficient aromatic rings has recently garnered much attention by supramolecular chemists, the observation of these interactions is not a recent discovery. Therefore, we begin with a historical perspective on early examples of anions interacting with electron-deficient arenes. An introduction to recent (and not so recent) computational investigations concerning anions and electron-deficient aromatic rings as well as a brief structural survey of crystalline examples of this interaction are provided. Finally, the limited solution-based observations of anions interacting with electron-deficient aromatic rings are summarized to introduce our current investigations in this area. We highlight three different systems from our lab where anion-arene interactions have been investigated. First, we show that tandem hydrogen bonds and anion-arene interactions augment halide binding in solution. Second, a crystallographic and computational study highlights the multiple types of interactions possible between anions and electron-deficient arenes. Third, we summarize the first example of a class of designed receptors that emphasize the different types of anion-arene interactions possible in solution.

  17. Effect of proquinazid and copper hydroxide on homeostasis of anions in winter wheat plants in generative phase of development

    Directory of Open Access Journals (Sweden)

    M. E. Riazanova

    2015-03-01

    Full Text Available The study deals with the effect of proquinazid and copper oxide application on structural characteristics and resistance of wheat to powdery mildew, as well as remobilisation and redistribution of anions pools at generative stage of development. The trial series was conducted in the experimental agricultural production of the Institute of Plant Physiology and Genetics, National Academy of Sciences of Ukraine. Field experiments were carried out with Smuglyanka variety of winter wheat. The trial series included the application of fungicides such as Talius (proquinazid, 200 g/L 0,25 L/ha and Kocide 2000 (copper hydroxide, 350 g/kg 150 and 300 g/ha, and combination of both fungicides. Sprays were applied at tillering stage in autumn in the first trial series and at tillering-booting stage in spring in the second one. Assessment of affected plants by powdery mildew was carried out visually in points. Anion concentration was determined with the use of ion chromatography. Application of fungicides at tillering stage increases the amount of productive stems in wheat plants. The highest effect was recorded for application of copper hydroxide at dose of 300 g/ha in autumn. Analysis of plants affected by powdery mildew shows that application of proquinazid and its composition with copper hydroxide provides sustained protection against Blumeria graminis (DC Speer. Application of fungicides at tillering stage contributes to increase of the pool of free nitrogen, phosphorus and sulfur anions in leaf tissues compared to control. These changes in anion composition may be caused by fungicide effect on activity of N, P, S transporters, as well as internal regulatory mechanisms of elements’ uptake by plants. Comparing the results of the autumn and spring application of fungicides should note the increase in concentration of free phosphates in wheat leaves in the 2nd trial with proquinazid and its composition with copper hydroxide. Accumulation of nitrogen in the

  18. Sediment Transport

    DEFF Research Database (Denmark)

    Liu, Zhou

    Flow and sediment transport are important in relation to several engineering topics, e.g. erosion around structures, backfilling of dredged channels and nearshore morphological change. The purpose of the present book is to describe both the basic hydrodynamics and the basic sediment transport...... mechanics. Chapter 1 deals with fundamentals in fluid mechanics with emphasis on bed shear stress by currents, while chapter 3 discusses wave boundary layer theory. They are both written with a view to sediment transport. Sediment transport in rivers, cross-shore and longshore are dealt with in chapters 2...

  19. Ocean transportation

    National Research Council Canada - National Science Library

    Frankel, Ernst G; Marcus, Henry S

    1973-01-01

    .... This analysis starts with a review of ocean transportation demand and supply including projections of ship capacity demand and world shipbuilding capacity under various economic and political assumptions...

  20. Determination of l-glutamic acid and γ-aminobutyric acid in mouse brain tissue utilizing GC-MS/MS.

    Science.gov (United States)

    Farthing, Christine A; Farthing, Don E; Gress, Ronald E; Sweet, Douglas H

    2017-11-15

    A rapid and selective method for the quantitation of neurotransmitters, l-Glutamic acid (GA) and γ-Aminobutyric acid (GABA), was developed and validated using gas chromatography-tandem mass spectrometry (GC-MS/MS). The novel method utilized a rapid online hot GC inlet gas phase sample derivatization and fast GC low thermal mass technology. The method calibration was linear from 0.5 to 100μg/mL, with limits of detections of 100ng/mL and 250ng/mL for GA and GABA, respectively. The method was used to investigate the effects of deletion of organic anion transporter 1 (Oat1) or Oat3 on murine CNS levels of GA and GABA at 3 and 18 mo of age, as compared to age matched wild-type (WT) animals. Whole brain concentrations of GA were comparable between WT, Oat1 -/- , and Oat3 -/- 18 mo at both 3 and 18 mo of age. Similarly, whole brain concentrations of GABA were not significantly altered in either knockout mouse strain at 3 or 18 mo of age, as compared to WT. These results indicate that the developed GC-MS/MS method provides sufficient sensitivity and selectivity for the quantitation of these neurotransmitters in mouse brain tissue. Furthermore, these results suggest that loss of Oat1 or Oat3 function in isolation does not result in significant alterations in brain tissue levels of GA or GABA. Copyright © 2017 Elsevier B.V. All rights reserved.