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1

Substrate specificity of the amino acid transporter PAT1  

Microsoft Academic Search

Summary.  The proton coupled amino acid transporter PAT1 expressed in intestine, brain, and other organs accepts L- and D-proline, glycine,\\u000a and L-alanine but also pharmaceutically active amino acid derivatives such as 3-amino-1-propanesulfonic acid, L-azetidine-2-carboxylic\\u000a acid, and cis-4-hydroxy-D-proline as substrates. We systematically analyzed the structural requirements for PAT1 substrates\\u000a by testing 87 amino acids, proline homologs, indoles, and derivatives. Affinity data and

L. Metzner; K. Neubert; M. Brandsch

2006-01-01

2

Substrate specificity of the amino acid transporter PAT1.  

PubMed

The proton coupled amino acid transporter PAT1 expressed in intestine, brain, and other organs accepts L- and D-proline, glycine, and L-alanine but also pharmaceutically active amino acid derivatives such as 3-amino-1-propanesulfonic acid, L-azetidine-2-carboxylic acid, and cis-4-hydroxy-D-proline as substrates. We systematically analyzed the structural requirements for PAT1 substrates by testing 87 amino acids, proline homologs, indoles, and derivatives. Affinity data and effects on membrane potential were determined using Caco-2 cells. For aliphatic amino acids, a blocked carboxyl group, the distance between amino and carboxyl group, and the position of the hydroxyl group are affinity limiting factors. Methylation of the amino group enhances substrate affinity. Hetero atoms in the proline template are well tolerated. Aromatic alpha-amino acids display low affinity. PAT1 interacts strongly with heterocyclic aromatic acids containing an indole scaffold. The structural requirements of PAT1 substrates elucidated in this study will be useful for the development of prodrugs. PMID:16699824

Metzner, L; Neubert, K; Brandsch, M

2006-05-15

3

Function and expression of the proton-coupled amino acid transporter PAT1 along the rat gastrointestinal tract: implications for intestinal absorption of gaboxadol  

PubMed Central

BACKGROUND AND PURPOSE Intestinal absorption via membrane transporters may determine the pharmacokinetics of drug compounds. The hypothesis is that oral absorption of gaboxadol (4,5,6,7-tetrahydroisoxazolo [5,4-c] pyridine-3-ol) in rats occurs via the proton-coupled amino acid transporter, rPAT1 (encoded by the gene rSlc36a1). Consequently, we aimed to elucidate the in vivo role of rPAT1 in the absorption of gaboxadol from various intestinal segments obtained from Sprague-Dawley rats. EXPERIMENTAL APPROACH The absorption of gaboxadol was investigated following its administration into four different intestinal segments. The intestinal expression of rSlc36a1 mRNA was measured by quantitative real-time PCR. Furthermore, the hPAT1-/rPAT1-mediated transport of gaboxadol or L-proline was studied in hPAT1-expressing Xenopus laevis oocytes, Caco-2 cell monolayers and excised segments of the rat intestine. KEY RESULTS The absorption fraction of gaboxadol was high (81.3–91.3%) following its administration into the stomach, duodenum and jejunum, but low (4.2%) after administration into the colon. The pharmacokinetics of gaboxadol were modified by the co-administration of L-tryptophan (an hPAT1 inhibitor) and L-proline (an hPAT1 substrate). The in vitro carrier-mediated uptake rate of L-proline in the excised intestinal segments was highest in the mid jejunum and lowest in the colon. The in vitro uptake and the in vivo absorption correlated with the expression of rSlc36a1 mRNA along the rat intestine. CONCLUSIONS AND IMPLICATIONS These results suggest that PAT1 mediates the intestinal absorption of gaboxadol and therefore determines its oral bioavailability. This has implications for the in vivo role of PAT1 and may have an influence on the design of pharmaceutical formulations of PAT1 substrates.

Broberg, ML; Holm, R; T?nsberg, H; Fr?lund, S; Ewon, KB; Nielsen, AL; Brodin, B; Jensen, A; Kall, MA; Christensen, KV; Nielsen, CU

2012-01-01

4

The ABC transporter proteins Pat1 and Pat2 are required for import of long-chain fatty acids into peroxisomes of Saccharomyces cerevisiae.  

PubMed Central

Peroxisomes of Saccharomyces cerevisiae are the exclusive site of fatty acid beta-oxidation. We have found that fatty acids reach the peroxisomal matrix via two independent pathways. The subcellular site of fatty acid activation varies with chain length of the substrate and dictates the pathway of substrate entry into peroxisomes. Medium-chain fatty acids are activated inside peroxisomes hby the acyl-CoA synthetase Faa2p. On the other hand, long-chain fatty acids are imported from the cytosolic pool of activated long-chain fatty acids via Pat1p and Pat2p, peroxisomal membrane proteins belonging to the ATP binding cassette transporter superfamily. Pat1p and Pat2p are the first examples of membrane proteins involved in metabolite transport across the peroxisomal membrane. Images

Hettema, E H; van Roermund, C W; Distel, B; van den Berg, M; Vilela, C; Rodrigues-Pousada, C; Wanders, R J; Tabak, H F

1996-01-01

5

Proton-Assisted Amino Acid Transporter PAT1 Complexes with Rag GTPases and Activates TORC1 on Late Endosomal and Lysosomal Membranes  

PubMed Central

Mammalian Target of Rapamycin Complex 1 (mTORC1) is activated by growth factor-regulated phosphoinositide 3-kinase (PI3K)/Akt/Rheb signalling and extracellular amino acids (AAs) to promote growth and proliferation. These AAs induce translocation of mTOR to late endosomes and lysosomes (LELs), subsequent activation via mechanisms involving the presence of intralumenal AAs, and interaction between mTORC1 and a multiprotein assembly containing Rag GTPases and the heterotrimeric Ragulator complex. However, the mechanisms by which AAs control these different aspects of mTORC1 activation are not well understood. We have recently shown that intracellular Proton-assisted Amino acid Transporter 1 (PAT1)/SLC36A1 is an essential mediator of AA-dependent mTORC1 activation. Here we demonstrate in Human Embryonic Kidney (HEK-293) cells that PAT1 is primarily located on LELs, physically interacts with the Rag GTPases and is required for normal AA-dependent mTOR relocalisation. We also use the powerful in vivo genetic methodologies available in Drosophila to investigate the regulation of the PAT1/Rag/Ragulator complex. We show that GFP-tagged PATs reside at both the cell surface and LELs in vivo, mirroring PAT1 distribution in several normal mammalian cell types. Elevated PI3K/Akt/Rheb signalling increases intracellular levels of PATs and synergistically enhances PAT-induced growth via a mechanism requiring endocytosis. In light of the recent identification of the vacuolar H+-ATPase as another Rag-interacting component, we propose a model in which PATs function as part of an AA-sensing engine that drives mTORC1 activation from LEL compartments.

Ogmundsdottir, Margret H.; Heublein, Sabine; Kazi, Shubana; Reynolds, Bruno; Visvalingam, Shivanthy M.; Shaw, Michael K.; Goberdhan, Deborah C. I.

2012-01-01

6

Enhanced Expression of Adenovirus-Mediated Sodium Iodide Symporter Gene in MCF7 Breast Cancer Cells with Retinoic Acid Treatment  

Microsoft Academic Search

Increased expression of the sodium iodide symporter (NIS) is re- quired for effective radioiodine treatment and reporter gene imaging of breast cancer. We investigated the effect of retinoic acid on adenovirus-mediated expression of the human NIS gene in the MCF-7 breast cancer cell line. Methods: The MCF-7 cell line was infected with recombinant adenovirus carry- ing the human NIS gene

Soo Jeong Lim; Jin Chul Paeng; Sung Jin Kim; Sang Yoon Kim; Heuiran Lee; Dae Hyuk Moon

2007-01-01

7

PAT-1 safety analysis report addendum.  

SciTech Connect

The Plutonium Air Transportable Package, Model PAT-1, is certified under Title 10, Code of Federal Regulations Part 71 by the U.S. Nuclear Regulatory Commission (NRC) per Certificate of Compliance (CoC) USA/0361B(U)F-96 (currently Revision 9). The purpose of this SAR Addendum is to incorporate plutonium (Pu) metal as a new payload for the PAT-1 package. The Pu metal is packed in an inner container (designated the T-Ampoule) that replaces the PC-1 inner container. The documentation and results from analysis contained in this addendum demonstrate that the replacement of the PC-1 and associated packaging material with the T-Ampoule and associated packaging with the addition of the plutonium metal content are not significant with respect to the design, operating characteristics, or safe performance of the containment system and prevention of criticality when the package is subjected to the tests specified in 10 CFR 71.71, 71.73 and 71.74.

Weiner, Ruth F.; Schmale, David T.; Kalan, Robert J.; Akin, Lili A.; Miller, David Russell; Knorovsky, Gerald Albert; Yoshimura, Richard Hiroyuki; Lopez, Carlos; Harding, David Cameron; Jones, Perry L.; Morrow, Charles W.

2010-09-01

8

PAT1, a new member of the GRAS family, is involved in phytochrome A signal transduction  

PubMed Central

Light signaling via the phytochrome A (phyA) photoreceptor controls basic plant developmental processes including de-etiolation and hypocotyl elongation. We have identified a new Arabidopsis mutant, pat (phytochrome A signal transduction)1-1, which shows strongly reduced responses in continuous far-red light. Physiological and molecular data indicate that this mutant is disrupted at an early step of phyA signal transduction. The PAT1 gene encodes a cytoplasmic protein of 490 amino acids with sequence homologies to the plant-specific GRAS regulatory protein family. In the pat1-1 mutant, a T-DNA insertion introduces a premature stop codon, which likely results in the production of a truncated PAT1 protein of 341 amino acids. The semidominant phenotype of this mutant can be recapitulated by overexpression of an appropriately truncated PAT1 gene in the wild type. The results indicate that the truncated PAT1 protein acts in a dominant-negative fashion to inhibit phyA signaling.

Bolle, Cordelia; Koncz, Csaba; Chua, Nam-Hai

2000-01-01

9

Systemic Retinoic Acid Treatment Induces Sodium\\/Iodide Symporter Expression and Radioiodide Uptake in Mouse Breast Cancer Models  

Microsoft Academic Search

Lactating breast tissue and some breast cancers express the sodium\\/ iodide symporter (NIS) and concentrate iodide. We recently demonstrated that all-trans retinoic acid (tRA) induces both NIS gene expression and iodide accumulation in vitro in well-differentiated human breast cancer cells (MCF-7). In the present study, we investigated the in vivo efficacy and specificity of tRA-stimulated iodide accumulation in mouse breast

Takahiko Kogai; Yoko Kanamoto; Lisa H. Che; Katsumi Taki; Farhad Moatamed; James J. Schultz; Gregory A. Brent

2004-01-01

10

Retinoic acid induces sodiumyiodide symporter gene expression and radioiodide uptake in the MCF7 breast cancer cell line  

Microsoft Academic Search

The sodiumyiodide symporter (NIS) stimulates iodide uptake in normal lactating breast, but is not known to be active in nonlac- tating breast or breast cancer. We studied NIS gene regulation and iodide uptake in MCF-7 cells, an estrogen receptor (ER)-positive human breast cancer cell line. All-trans retinoic acid (tRA) treat- ment stimulated iodide uptake in a time- and dose-dependent fashion

Takahiko Kogai; James J. Schultz; Laura S. Johnson; Min Huang; Gregory A. Brent

11

The Identification of Pats1, a Novel Gene Locus Required for Cytokinesis in Dictyostelium discoideum  

PubMed Central

Here, we describe the identification and characterization of the cytokinesis-deficient mutant cell line 17HG5, which was generated in a restriction enzyme–mediated integration mutagenesis screen designed to isolate genes required for cytokinesis in Dictyostelium discoideum. Phenotypic characterization of the 17HG5 cell line revealed no apparent defects in the global functionality of the actomyosin cytoskeleton except for the observed cytokinesis defect when grown in suspension culture. Plasmid rescue was used to identify the disrupted gene locus (pats1; protein associated with the transduction of signal 1) that caused the cytokinesis defect. Disruption of the pats1 locus was recreated through homologous recombination in several independent cell lines, each recapitulating the cytokinesis-defective phenotype and thereby confirming that this gene locus is important for proper cytokinesis. Sequence data obtained by analysis of the genomic region flanking the inserted restriction enzyme–mediated integration plasmid revealed an 8892-bp genomic open reading frame encoding a 2964-amino-acid protein. The putative pats1 protein contains 3 regulatory domains (RI-phosphatase, RII-GTP–binding, R-III protein kinase), 13 leucine-rich repeats, and 8 WD-40 repeats. These regulatory domains coupled with the protein–protein interacting domains suggest that pats1 is involved in signal transduction during cytokinesis in Dictyostelium.

Abysalh, Jonathan C.; Kuchnicki, Lisa L.; Larochelle, Denis A.

2003-01-01

12

Retinoic Acid Increases Sodium\\/Iodide Symporter mRNA Levels in Human Thyroid Cancer Cell Lines and Suppresses Expression of Functional Symporter in Nontransformed FRTL-5 Rat Thyroid Cells  

Microsoft Academic Search

Decreased iodide uptake in de-differentiated thyroid carcinomas impedes radioiodide therapy. RT-PCR analysis revealed reduced expression of Na+\\/I?symporter (NIS) mRNA in human thyroid carcinomas as compared to normal thyroid. However, in follicular thyroid carcinoma cell lines FTC-133 and FTC-238, treatment with 1 ?M all-transretinoic acid (RA) markedly increased NIS mRNA levels. Anaplastic thyroid carcinoma cell lines HTh74 and C643 showed basal

C. Schmutzler; R. Winzer; J. Meissner-Weigl; J. Köhrle

1997-01-01

13

Conserved charged amino acid residues in the extracellular region of sodium/iodide symporter are critical for iodide transport activity  

PubMed Central

Background Sodium/iodide symporter (NIS) mediates the active transport and accumulation of iodide from the blood into the thyroid gland. His-226 located in the extracellular region of NIS has been demonstrated to be critical for iodide transport in our previous study. The conserved charged amino acid residues in the extracellular region of NIS were therefore characterized in this study. Methods Fourteen charged residues (Arg-9, Glu-79, Arg-82, Lys-86, Asp-163, His-226, Arg-228, Asp-233, Asp-237, Arg-239, Arg-241, Asp-311, Asp-322, and Asp-331) were replaced by alanine. Iodide uptake abilities of mutants were evaluated by steady-state and kinetic analysis. The three-dimensional comparative protein structure of NIS was further modeled using sodium/glucose transporter as the reference protein. Results All the NIS mutants were expressed normally in the cells and targeted correctly to the plasma membrane. However, these mutants, except R9A, displayed severe defects on the iodide uptake. Further kinetic analysis revealed that mutations at conserved positively charged amino acid residues in the extracellular region of NIS led to decrease NIS-mediated iodide uptake activity by reducing the maximal rate of iodide transport, while mutations at conserved negatively charged residues led to decrease iodide transport by increasing dissociation between NIS mutants and iodide. Conclusions This is the first report characterizing thoroughly the functional significance of conserved charged amino acid residues in the extracellular region of NIS. Our data suggested that conserved charged amino acid residues, except Arg-9, in the extracellular region of NIS were critical for iodide transport.

2010-01-01

14

Retinoic acid induces sodium/iodide symporter gene expression and radioiodide uptake in the MCF-7 breast cancer cell line  

PubMed Central

The sodium/iodide symporter (NIS) stimulates iodide uptake in normal lactating breast, but is not known to be active in nonlactating breast or breast cancer. We studied NIS gene regulation and iodide uptake in MCF-7 cells, an estrogen receptor (ER)-positive human breast cancer cell line. All-trans retinoic acid (tRA) treatment stimulated iodide uptake in a time- and dose-dependent fashion up to ?9.4-fold above baseline. Stimulation with selective retinoid compounds indicated that the induction of iodide uptake was mediated by retinoic acid receptor. Treatment with tRA markedly stimulated NIS mRNA and immunoreactive protein (?68 kDa). tRA stimulated NIS gene transcription ?4-fold, as shown by nuclear run-on assay. No induction of iodide uptake was observed with RA treatment of an ER-negative human breast cancer cell line, MDA-MB 231, or a normal human breast cell line, MCF-12A. The iodide efflux rate of tRA-treated MCF-7 cells was slow (t1/2 = 24 min), compared with that in FRTL-5 thyroid cells (t1/2 = 3.9 min), favoring iodide retention in MCF-7 cells. An in vitro clonogenic assay demonstrated selective cytotoxicity with 131I after tRA stimulation of MCF-7 cells. tRA up-regulates NIS gene expression and iodide uptake in an ER-positive breast cancer cell line. Stimulation of radioiodide uptake after systemic retinoid treatment may be useful for diagnosis and treatment of some differentiated breast cancers.

Kogai, Takahiko; Schultz, James J.; Johnson, Laura S.; Huang, Min; Brent, Gregory A.

2000-01-01

15

Retinoic acid induces sodium/iodide symporter gene expression and radioiodide uptake in the MCF-7 breast cancer cell line.  

PubMed

The sodium/iodide symporter (NIS) stimulates iodide uptake in normal lactating breast, but is not known to be active in nonlactating breast or breast cancer. We studied NIS gene regulation and iodide uptake in MCF-7 cells, an estrogen receptor (ER)-positive human breast cancer cell line. All-trans retinoic acid (tRA) treatment stimulated iodide uptake in a time- and dose-dependent fashion up to approximately 9.4-fold above baseline. Stimulation with selective retinoid compounds indicated that the induction of iodide uptake was mediated by retinoic acid receptor. Treatment with tRA markedly stimulated NIS mRNA and immunoreactive protein ( approximately 68 kDa). tRA stimulated NIS gene transcription approximately 4-fold, as shown by nuclear run-on assay. No induction of iodide uptake was observed with RA treatment of an ER-negative human breast cancer cell line, MDA-MB 231, or a normal human breast cell line, MCF-12A. The iodide efflux rate of tRA-treated MCF-7 cells was slow (t(1/2) = 24 min), compared with that in FRTL-5 thyroid cells (t(1/2) = 3.9 min), favoring iodide retention in MCF-7 cells. An in vitro clonogenic assay demonstrated selective cytotoxicity with (131)I after tRA stimulation of MCF-7 cells. tRA up-regulates NIS gene expression and iodide uptake in an ER-positive breast cancer cell line. Stimulation of radioiodide uptake after systemic retinoid treatment may be useful for diagnosis and treatment of some differentiated breast cancers. PMID:10890895

Kogai, T; Schultz, J J; Johnson, L S; Huang, M; Brent, G A

2000-07-18

16

Air transport of plutonium metal : content expansion initiative for the Plutonium Air Transportable (PAT1) packaging  

Microsoft Academic Search

The National Nuclear Security Administration (NNSA) has submitted an application to the Nuclear Regulatory Commission (NRC) for the air shipment of plutonium metal within the Plutonium Air Transportable (PAT-1) packaging. The PAT-1 packaging is currently authorized for the air transport of plutonium oxide in solid form only. The INMM presentation will provide a limited overview of the scope of the

Paul T. Mann; Michael L. Caviness; Richard Hiroyuki Yoshimura

2010-01-01

17

Retinoic acid-induced stimulation of sodium iodide symporter expression and cytotoxicity of radioiodine in prostate cancer cells.  

PubMed

We reported recently the induction of androgen-dependent iodide uptake activity in the human prostatic adenocarcinoma cell line LNCaP using a prostate-specific antigen (PSA) promoter-directed expression of the sodium iodide symporter (NIS) gene. This offers the potential to treat prostate cancer with radioiodine. In the current study, we examined the regulation of PSA promoter-directed NIS expression and therapeutic effectiveness of (131)I in LNCaP cells by all-trans-retinoic acid (atRA). For this purpose, NIS mRNA and protein expression levels in the NIS-transfected LNCaP cell line NP-1 were examined by Northern and Western blot analysis following incubation with atRA (10 (-9) to 10(-6) M) in the presence of 10(-9) M mibolerone (mib). In addition, NIS functional activity was measured by iodide uptake assay, and in vitro cytotoxicity of (131)I was examined by in vitro clonogenic assay. Following incubation with atRA, NIS mRNA levels in NP-1 cells were stimulated 3-fold in a concentration-dependent manner, whereas NIS protein levels increased 2.3-fold and iodide accumulation was stimulated 1.45-fold. This stimulatory effect of atRA, which has been shown to be retinoic acid receptor mediated, was completely blocked by the pure androgen receptor antagonist casodex (10(-6) M), indicating that it is androgen receptor dependent. The selective killing effect of (131)I in NP-1 cells was 50% in NP-1 cells incubated with 10(-9) M mib. This was increased to 90% in NP-1 cells treated with atRA (10(-7) M) plus 10(-9) M mib. In conclusion, treatment with atRA increases NIS expression levels and selective killing effect of (131)I in prostate cancer cells stably expressing NIS under the control of the PSA promoter. Therefore atRA may be used to enhance the therapeutic response to radioiodine in prostate cancer cells following PSA promoter-directed NIS gene delivery. PMID:12865321

Spitzweg, C; Scholz, I V; Bergert, E R; Tindall, D J; Young, C Y F; Göke, B; Morris, J C

2003-08-01

18

Structural analysis of the yeast Dhh1-Pat1 complex reveals how Dhh1 engages Pat1, Edc3 and RNA in mutually exclusive interactions  

PubMed Central

Translational repression and deadenylation of eukaryotic mRNAs result either in the sequestration of the transcripts in a nontranslatable pool or in their degradation. Removal of the 5? cap structure is a crucial step that commits deadenylated mRNAs to 5?-to-3? degradation. Pat1, Edc3 and the DEAD-box protein Dhh1 are evolutionary conserved factors known to participate in both translational repression and decapping, but their interplay is currently unclear. We report the 2.8 Å resolution structure of yeast Dhh1 bound to the N-terminal domain of Pat1. The structure shows how Pat1 wraps around the C-terminal RecA domain of Dhh1, docking onto the Phe-Asp-Phe (FDF) binding site. The FDF-binding site of Dhh1 also recognizes Edc3, revealing why the binding of Pat1 and Edc3 on Dhh1 are mutually exclusive events. Using co-immunoprecipitation assays and structure-based mutants, we demonstrate that the mode of Dhh1-Pat1 recognition is conserved in humans. Pat1 and Edc3 also interfere and compete with the RNA-binding properties of Dhh1. Mapping the RNA-binding sites on Dhh1 with a crosslinking–mass spectrometry approach shows a large RNA-binding surface around the C-terminal RecA domain, including the FDF-binding pocket. The results suggest a model for how Dhh1-containing messenger ribonucleoprotein particles might be remodeled upon Pat1 and Edc3 binding.

Sharif, Humayun; Ozgur, Sevim; Sharma, Kundan; Basquin, Claire; Urlaub, Henning; Conti, Elena

2013-01-01

19

Air transport of plutonium metal : content expansion initiative for the Plutonium Air Transportable (PAT-1) packaging.  

SciTech Connect

The National Nuclear Security Administration (NNSA) has submitted an application to the Nuclear Regulatory Commission (NRC) for the air shipment of plutonium metal within the Plutonium Air Transportable (PAT-1) packaging. The PAT-1 packaging is currently authorized for the air transport of plutonium oxide in solid form only. The INMM presentation will provide a limited overview of the scope of the plutonium metal initiative and provide a status of the NNSA application to the NRC.

Mann, Paul T. (National Nuclear Security Administration); Caviness, Michael L. (Los Alamos National Laboratory); Yoshimura, Richard Hiroyuki

2010-06-01

20

Cloning of the Human Sodium Iodide Symporter  

Microsoft Academic Search

The iodide concentrating activity of the thyroid gland is essential to the production of thyroid hormone and also provides a mechanism for the treatment of thyroid cancer by radioiodine ablation. We report here the nucleotide and amino acid sequence of the human sodium iodide symporter (hNIS), which mediates the iodide uptake activity in the thyroid gland. An open reading frame

P. A. Smanik; Q. Liu; T. L. Furminger; K. Ryu; S. Xing; E. L. Mazzaferri; S. M. Jhiang

1996-01-01

21

Diauxic shift-dependent relocalization of decapping activators Dhh1 and Pat1 to polysomal complexes  

PubMed Central

Dhh1 and Pat1 in yeast are mRNA decapping activators/translational repressors thought to play key roles in the transition of mRNAs from translation to degradation. However, little is known about the physical and functional relationships between these proteins and the translation machinery. We describe a previously unknown type of diauxic shift-dependent modulation of the intracellular locations of Dhh1 and Pat1. Like the formation of P bodies, this phenomenon changes the spatial relationship between components involved in translation and mRNA degradation. We report significant spatial separation of Dhh1 and Pat1 from ribosomes in exponentially growing cells. Moreover, biochemical analyses reveal that these proteins are excluded from polysomal complexes in exponentially growing cells, indicating that they may not be associated with active states of the translation machinery. In contrast, under diauxic growth shift conditions, Dhh1 and Pat1 are found to co-localize with polysomal complexes. This work suggests that Dhh1 and Pat1 functions are modulated by a re-localization mechanism that involves eIF4A. Pull-down experiments reveal that the intracellular binding partners of Dhh1 and Pat1 change as cells undergo the diauxic growth shift. This reveals a new dimension to the relationship between translation activity and interactions between mRNA, the translation machinery and decapping activator proteins.

Drummond, Sheona P.; Hildyard, John; Firczuk, Helena; Reamtong, Onrapak; Li, Ning; Kannambath, Shichina; Claydon, Amy J.; Beynon, Robert J.; Eyers, Claire E.; McCarthy, John E. G.

2011-01-01

22

Putative anion transporter-1 (Pat-1, Slc26a6) contributes to intracellular pH regulation during H+-dipeptide transport in duodenal villous epithelium  

PubMed Central

The majority of dietary amino acids are absorbed via the H+-di-/tripeptide transporter Pept1 of the small intestine. Proton influx via Pept1 requires maintenance of intracellular pH (pHi) to sustain the driving force for peptide absorption. The apical membrane Na+/H+ exchanger Nhe3 plays a major role in minimizing epithelial acidification during H+-di-/tripeptide absorption. However, the contributions of HCO3?-dependent transporters to this process have not been elucidated. In this study, we investigate the role of putative anion transporter-1 (Pat-1), an apical membrane anion exchanger, in epithelial pHi regulation during H+-peptide absorption. Using wild-type (WT) and Pat-1(?) mice, Ussing chambers were employed to measure the short-circuit current (Isc) associated with Pept1-mediated glycyl-sarcosine (Gly-Sar) absorption. Microfluorometry was used to measure pHi and Cl?/HCO3? exchange in the upper villous epithelium. In CO2/HCO3?-buffered Ringers, WT small intestine showed significant Gly-Sar-induced Isc and efficient pHi regulation during pharmacological inhibition of Nhe3 activity. In contrast, epithelial acidification and reduced Isc response to Gly-Sar exposure occurred during pharmacological inhibition of Cl?/HCO3? exchange and in the Pat-1(?) intestine. Pat-1 interacts with carbonic anhydrase II (CAII), and studies using CAII(?) intestine or the pharmacological inhibitor methazolamide on WT intestine resulted in increased epithelial acidification during Gly-Sar exposure. Increased epithelial acidification during Gly-Sar exposure also occurred in WT intestine during inhibition of luminal extracellular CA activity. Measurement of Cl?/HCO3? exchange in the presence of Gly-Sar revealed an increased rate of Cl?OUT/HCO3?IN exchange that was both Pat-1 dependent and CA dependent. In conclusion, Pat-1 Cl?/HCO3? exchange contributes to pHi regulation in the villous epithelium during H+-dipeptide absorption, possibly by providing a HCO3? import pathway.

Simpson, Janet E.; Walker, Nancy M.; Supuran, Claudiu T.; Soleimani, Manoocher

2010-01-01

23

RNA-related nuclear functions of human Pat1b, the P-body mRNA decay factor.  

PubMed

The evolutionarily conserved Pat1 proteins are P-body components recently shown to play important roles in cytoplasmic gene expression control. Using human cell lines, we demonstrate that human Pat1b is a shuttling protein whose nuclear export is mediated via a consensus NES sequence and Crm1, as evidenced by leptomycin B (LMB) treatment. However, not all P-body components are nucleocytoplasmic proteins; rck/p54, Dcp1a, Edc3, Ge-1, and Xrn1 are insensitive to LMB and remain cytoplasmic in its presence. Nuclear Pat1b localizes to PML-associated foci and SC35-containing splicing speckles in a transcription-dependent manner, whereas in the absence of RNA synthesis, Pat1b redistributes to crescent-shaped nucleolar caps. Furthermore, inhibition of splicing by spliceostatin A leads to the reorganization of SC35 speckles, which is closely mirrored by Pat1b, indicating that it may also be involved in splicing processes. Of interest, Pat1b retention in these three nuclear compartments is mediated via distinct regions of the protein. Examination of the nuclear distribution of 4E-T(ransporter), an additional P-body nucleocytoplasmic protein, revealed that 4E-T colocalizes with Pat1b in PML-associated foci but not in nucleolar caps. Taken together, our findings strongly suggest that Pat1b participates in several RNA-related nuclear processes in addition to its multiple regulatory roles in the cytoplasm. PMID:22090346

Marnef, Aline; Weil, Dominique; Standart, Nancy

2011-11-16

24

RNA-related nuclear functions of human Pat1b, the P-body mRNA decay factor  

PubMed Central

The evolutionarily conserved Pat1 proteins are P-body components recently shown to play important roles in cytoplasmic gene expression control. Using human cell lines, we demonstrate that human Pat1b is a shuttling protein whose nuclear export is mediated via a consensus NES sequence and Crm1, as evidenced by leptomycin B (LMB) treatment. However, not all P-body components are nucleocytoplasmic proteins; rck/p54, Dcp1a, Edc3, Ge-1, and Xrn1 are insensitive to LMB and remain cytoplasmic in its presence. Nuclear Pat1b localizes to PML–associated foci and SC35-containing splicing speckles in a transcription-dependent manner, whereas in the absence of RNA synthesis, Pat1b redistributes to crescent-shaped nucleolar caps. Furthermore, inhibition of splicing by spliceostatin A leads to the reorganization of SC35 speckles, which is closely mirrored by Pat1b, indicating that it may also be involved in splicing processes. Of interest, Pat1b retention in these three nuclear compartments is mediated via distinct regions of the protein. Examination of the nuclear distribution of 4E-T(ransporter), an additional P-body nucleocytoplasmic protein, revealed that 4E-T colocalizes with Pat1b in PML-associated foci but not in nucleolar caps. Taken together, our findings strongly suggest that Pat1b participates in several RNA-related nuclear processes in addition to its multiple regulatory roles in the cytoplasm.

Marnef, Aline; Weil, Dominique; Standart, Nancy

2012-01-01

25

PAT-1 safety analysis report addendum author responses to request for additional information.  

SciTech Connect

The Plutonium Air Transportable Package, Model PAT-1, is certified under Title 10, Code of Federal Regulations Part 71 by the U.S. Nuclear Regulatory Commission (NRC) per Certificate of Compliance (CoC) USA/0361B(U)F-96 (currently Revision 9). The National Nuclear Security Administration (NNSA) submitted SAND Report SAND2009-5822 to NRC that documented the incorporation of plutonium (Pu) metal as a new payload for the PAT-1 package. NRC responded with a Request for Additional Information (RAI), identifying information needed in connection with its review of the application. The purpose of this SAND report is to provide the authors responses to each RAI. SAND Report SAND2010-6106 containing the proposed changes to the Addendum is provided separately.

Weiner, Ruth F.; Schmale, David T.; Kalan, Robert J.; Akin, Lili A.; Miller, David Russell; Knorovsky, Gerald Albert; Yoshimura, Richard Hiroyuki; Lopez, Carlos; Harding, David Cameron; Jones, Perry L.; Morrow, Charles W.

2010-09-01

26

The human Pat1b protein: a novel mRNA deadenylation factor identified by a new immunoprecipitation technique  

PubMed Central

The complex of the yeast Lsm1p-7p proteins with Pat1p is an important mRNA decay factor that is involved in translational shutdown of deadenylated mRNAs and thus prepares these mRNAs for degradation. While the Lsm proteins are highly conserved, there is no unique mammalian homolog of Pat1p. To identify proteins that interact with human LSm1, we developed a novel immunoprecipitation technique that yields virtually pure immunocomplexes. Mass-spec analysis therefore identifies mostly true positives, avoiding tedious functional screening. The method unambiguously identified the Pat1p homolog in HeLa cells, Pat1b. When targeted to a reporter mRNA, Pat1b represses gene expression by inducing deadenylation of the mRNAs. This demonstrates that Pat1b, unlike yPat1p, acts as an mRNA-specific deadenylation factor, highlighting the emerging importance of deadenylation in the mRNA regulation of higher eukaryotes.

Totaro, Antonio; Renzi, Fabrizio; La Fata, Giorgio; Mattioli, Claudia; Raabe, Monika; Urlaub, Henning; Achsel, Tilmann

2011-01-01

27

Subcellular localization and interaction network of the mRNA decay activator Pat1 upon UV stress.  

PubMed

To identify nucleo-cytoplasmic shuttle proteins that relocate to the nucleus upon UV stress, we selected 18 targets on the basis of their conservation amongst eukaryotes and their relatively poor functional description. Their relocation was assayed using quantitative nuclear relocation assay (QNR). We focused on Pat1, a component of the cytoplasmic foci called processing bodies (p-bodies), because it had the strongest response to the stress. We verified that Pat1 accumulates in the nucleus after GFP tagging and fluorescence microscopy. Using tandem affinity purification coupled to a mass spectrometry shotgun detection and quantitation approach, we explored the dynamics of Pat1 protein-protein interaction network after UV stress. We have shown that Pat1 co-purifies with Dhh1 specifically upon UV stress. We observed that the nuclear accumulation of Pat1 upon UV stress is abolished in a dhh1? strain. These data provide the first evidence that Dhh1 is required for Pat1 nuclear relocation after UV stress. PMID:23847025

Bahassou-Benamri, Rachida; Davin, Anne-Hélène; Gaillard, Jean-Charles; Alonso, Beatrice; Odorico, Michael; Pible, Olivier; Armengaud, Jean; Godon, Christian

2013-08-13

28

Sodium ion-substrate symport in a marine bacterium.  

PubMed Central

Anaerobic suspensions of Alteromonas haloplanktis accumulated alpha-aminoisobutyric acid, by a sodium-dependent process, in response to an artificially imposed membrane potential in the presence or absence of a transmembrane chemical gradient of sodium. These results suggest that the transport of alpha-aminoisobutyrate by this organism occurs via Na+-substrate symport.

Niven, D F; MacLeod, R A

1980-01-01

29

Characterization of Gastric Na +\\/I ?Symporter of the Rat  

Microsoft Academic Search

Characterization of gastric Na+\\/I?symporter (NIS) of the rat was carried out. Sequencing of the open reading frame of gastric NIS mRNA showed only three nucleotide changes when compared with FRTL-5 NIS cDNA, and two of these changes led to amino acid changes. The results of Northern blot analysis showed that abundant NIS mRNA was expressed in the stomach when compared

Tomio Kotani; Yoshikazu Ogata; Ikuo Yamamoto; Yatsuki Aratake; Jun-Ichi Kawano; Tatsuo Suganuma; Sachiya Ohtaki

1998-01-01

30

Functional Activity of Pat-1 (Slc26a6) Cl?/HCO3? Exchange in the Lower Villus Epithelium of Murine Duodenum  

PubMed Central

Aims The apical membrane anion exchanger Pat-1 is expressed at significant levels in the lower villus epithelium of murine duodenum. However, previous studies of Cl?/HCO3? exchange in the lower villus have failed to demonstrate Pat-1 function. Those studies routinely included luminal glucose which induces Na+-coupled glucose transport and acidifies the villus epithelium. Since Pat-1 has been proposed to be an electrogenic 1Cl?/2HCO3? exchanger, membrane depolarization or cell acidification during glucose transport may obscure Pat-1 activity. Therefore, we investigated the effects of luminal glucose on Cl?IN/HCO3?OUT exchange activity in the lower villus epithelium. Methods Cl?IN/HCO3?OUT exchange of villus epithelium in duodenal mucosa from Pat-1 knockout (KO), Slc26a3 (Dra) KO, cystic fibrosis transmembrane conductance regulator (Cftr) KO and wild-type (WT) littermate mice was measured using the pH-sensitive dye BCECF. Short-circuit current (Isc) was measured in Ussing chambers. Results During glucose absorption, Cl?IN/HCO3?OUT exchange in the lower villus epithelium was abolished in the Dra KO and unaffected in the Pat-1 KO relative to WT. However, during electroneutral mannose absorption or electrogenic ?-D-methyl glucoside absorption, Cl?IN/HCO3?OUT exchange was reduced in both Pat-1 KO and Dra KO villi. Exposure to high [K+] abolished Cl?IN/HCO3?OUT exchange in the Dra KO but not the Dra/Cftr double KO epithelium, suggesting that Pat-1 activity is little affected by membrane depolarization except in the presence of Cftr. Conclusions The metabolic and electrogenic activity of glucose transport obscures Cl?IN/HCO3?OUT exchange activity of Pat-1 in the lower villus. The inhibitory effects of membrane depolarization on Pat-1 Cl?IN/HCO3?OUT exchange may require concurrent membrane association with Cftr.

Walker, Nancy M.; Simpson, Janet E.; Hoover, Erin E.; Brazill, Jennifer M.; Schweinfest, Clifford W.; Soleimani, Manoocher; Clarke, Lane L.

2010-01-01

31

Substrate-dependent proton antiport in neurotransmitter:sodium symporters  

PubMed Central

SUMMARY Neurotransmitter:sodium symporters (NSS), targets for psychostimulants and therapeutic drugs, play a critical role in neurotransmission. Whereas eukaryotic NSS exhibit Cl?-dependent transport, bacterial NSS feature Cl?-independent substrate transport. Recently we showed in LeuT and Tyt1 that mutation of an acidic side chain near one of the Na+-binding sites renders substrate binding and/or transport Cl? dependent. We reasoned that the negative charge - provided either by Cl? or by the transporter itself - is required for substrate translocation. Here we show that Tyt1 reconstituted in proteoliposomes is strictly dependent on the Na+ gradient and is stimulated by an inside negative membrane potential and by an inversely-oriented H+ gradient. Remarkably, Na+/substrate symport elicited H+ efflux, indicative of Na+/substrate symport-coupled H+ antiport. Mutations that render the transport phenotype Cl?-dependent essentially abolish the pH dependence. We propose unifying features of charge balance by all NSS members with similar mechanistic features but with different molecular solutions.

Zhao, Yongfang; Quick, Matthias; Shi, Lei; Mehler, Ernest L.; Weinstein, Harel; Javitch, Jonathan A.

2009-01-01

32

Evolutionary relationship between K(+) channels and symporters.  

PubMed Central

The hypothesis is presented that at least four families of putative K(+) symporter proteins, Trk and KtrAB from prokaryotes, Trk1,2 from fungi, and HKT1 from wheat, evolved from bacterial K(+) channel proteins. Details of this hypothesis are organized around the recently determined crystal structure of a bacterial K(+) channel: i. e., KcsA from Streptomyces lividans. Each of the four identical subunits of this channel has two fully transmembrane helices (designated M1 and M2), plus an intervening hairpin segment that determines the ion selectivity (designated P). The symporter sequences appear to contain four sequential M1-P-M2 motifs (MPM), which are likely to have arisen from gene duplication and fusion of the single MPM motif of a bacterial K(+) channel subunit. The homology of MPM motifs is supported by a statistical comparison of the numerical profiles derived from multiple sequence alignments formed for each protein family. Furthermore, these quantitative results indicate that the KtrAB family of symporters has remained closest to the single-MPM ancestor protein. Strong sequence evidence is also found for homology between the cytoplasmic C-terminus of numerous bacterial K(+) channels and the cytoplasm-resident TrkA and KtrA subunits of the Trk and KtrAB symporters, which in turn are homologous to known dinucleotide-binding domains of other proteins. The case for homology between bacterial K(+) channels and the four families of K(+) symporters is further supported by the accompanying manuscript, in which the patterns of residue conservation are demonstrated to be similar to each other and consistent with the known 3D structure of the KcsA K(+) channel.

Durell, S R; Hao, Y; Nakamura, T; Bakker, E P; Guy, H R

1999-01-01

33

Characterization of the Thyroid Na+\\/I- Symporter with an Anti-COOH Terminus Antibody  

Microsoft Academic Search

The Na+\\/I- symporter (NIS) is the plasma membrane protein that catalyzes active I- transport in the thyroid, the first step in thyroid hormone biogenesis. The cDNA encoding NIS was recently cloned in our laboratory and a secondary structure model proposed, suggesting that NIS is an intrinsic membrane protein (618 amino acids; ≈ 65.2 kDa predicted molecular mass) with 12 putative

Orlie Levy; Ge Dai; Claudia Riedel; Christopher S. Ginter; Elliot M. Paul; Adam N. Lebowitz; Nancy Carrasco

1997-01-01

34

The cellular decapping activators LSm1, Pat1, and Dhh1 control the ratio of subgenomic to genomic Flock House virus RNAs.  

PubMed

Positive-strand RNA viruses depend on recruited host factors to control critical replication steps. Previously, it was shown that replication of evolutionarily diverse positive-strand RNA viruses, such as hepatitis C virus and brome mosaic virus, depends on host decapping activators LSm1-7, Pat1, and Dhh1 (J. Diez et al., Proc. Natl. Acad. Sci. U. S. A. 97:3913-3918, 2000; A. Mas et al., J. Virol. 80:246 -251, 2006; N. Scheller et al., Proc. Natl. Acad. Sci. U. S. A. 106:13517-13522, 2009). By using a system that allows the replication of the insect Flock House virus (FHV) in yeast, here we show that LSm1-7, Pat1, and Dhh1 control the ratio of subgenomic RNA3 to genomic RNA1 production, a key feature in the FHV life cycle mediated by a long-distance base pairing within RNA1. Depletion of LSM1, PAT1, or DHH1 dramatically increased RNA3 accumulation during replication. This was not caused by differences between RNA1 and RNA3 steady-state levels in the absence of replication. Importantly, coimmunoprecipitation assays indicated that LSm1-7, Pat1, and Dhh1 interact with the FHV RNA genome and the viral polymerase. By using a strategy that allows dissecting different stages of the replication process, we found that LSm1-7, Pat1, and Dhh1 did not affect the early replication steps of RNA1 recruitment to the replication complex or RNA1 synthesis. Furthermore, their function on RNA3/RNA1 ratios was independent of the membrane compartment, where replication occurs and requires ATPase activity of the Dhh1 helicase. Together, these results support that LSm1-7, Pat1, and Dhh1 control RNA3 synthesis. Their described function in mediating cellular mRNP rearrangements suggests a parallel role in mediating key viral RNP transitions, such as the one required to maintain the balance between the alternative FHV RNA1 conformations that control RNA3 synthesis. PMID:23536653

Giménez-Barcons, Mireia; Alves-Rodrigues, Isabel; Jungfleisch, Jennifer; Van Wynsberghe, Priscilla M; Ahlquist, Paul; Díez, Juana

2013-03-27

35

Sucrose-mediated transcriptional regulation of sucrose symporter activity in the phloem.  

SciTech Connect

This project was based on our discovery that sucrose acts as a signaling molecule that regulates the activity of a proton-sucrose symporter in sugar beet leaf tissue. A major objective here was determining how sucrose transporter activity is being regulated. When sucrose accumulates in the phloem sucrose transport activity drops dramatically. Western blots of plasma membrane proteins isolated from sucrose treated leaves showed that the loss of sucrose transport activity was proportional to a decline in symporter abundance, demonstrating that sucrose transport is regulated by changes in the amount of BvSUT1 protein. BvSUT1 transcript levels decreased in parallel with the loss of sucrose transport activity. Nuclear run-on experiments demonstrated that BvSUT1 gene transcription was repressed significantly in nuclei from leaves fed 100 mM exogenous sucrose, showing that sucrose-dependent modulation of BvSUT1 mRNA levels is mediated by changes in transcription. To identify which secondary messenger systems might be involved in regulating symporter activity, we used a variety of pharmacological agents to probe for a role of calcium or protein phosphorylation in sucrose signaling. In a detailed analysis, only okadaic acid altered sucrose transport activity. These results suggest a protein phosphatase is involved. We hypothesized that protein kinase inhibitors would have a neutral affect or increase symporter transcription. Transpirational feeding of the protein kinase inhibitor staurosporine had no impact on sucrose transport while calphostin C, an inhibitor of protein kinase C, caused a 60% increase. These data provided good evidence that protein phosphorylation plays a central role in regulating sucrose symporter expression and sucrose transport activity. To determine whether protein phosphorylation is involved in sucrose regulation of proton-sucrose symporter activity, we pre-fed leaves with staurosporine for 4 h and then fed the treated leaves water or 100 mM sucrose for an additional 20 h. Sucrose transport activity was higher than the water control in both staurosporine/water- and staurosporine/sucrose-fed leaves. In contrast, sucrose transport activity was only 40% of the water control in sucrose-fed leaves. Taken together, these results showed that a phosphorylation-dependent signal transduction pathway is involved in sucrose-mediated regulation of BvSUT1 gene expression, sucrose transport activity, and ultimately phloem loading. Publications originating from this work: Vaughn MW, GN. Harrington, and DR Bush 2002. Sucrose-mediated transcriptional regulation of sucrose symporter activity in the phloem. Proc. Natl. Acad. Sci. USA 99:10876-10880 Ransom-Hodgkins W, MW Vaughn, and DR Bush 2003. Protein phosphorylation mediates a key step in sucrose-regulation of the expression and transport activity of a beet proton-sucrose symporter. Planta 217:483-489 Harrington GN and Bush DR 2003. The bifunctional role of hexokinase in metabolism and glucose signaling. Plant Cell 15: 2493-2496

Matt Vaughn Greg Harrington Daniel R Bush

2002-08-06

36

The decapping activator Lsm1p-7p-Pat1p complex has the intrinsic ability to distinguish between oligoadenylated and polyadenylated RNAs  

PubMed Central

Decapping is a critical step in mRNA decay. In the 5?-to-3? mRNA decay pathway conserved in all eukaryotes, decay is initiated by poly(A) shortening, and oligoadenylated mRNAs (but not polyadenylated mRNAs) are selectively decapped allowing their subsequent degradation by 5? to 3? exonucleolysis. The highly conserved heptameric Lsm1p-7p complex (made up of the seven Sm-like proteins, Lsm1p–Lsm7p) and its interacting partner Pat1p activate decapping by an unknown mechanism and localize with other decapping factors to the P-bodies in the cytoplasm. The Lsm1p-7p–Pat1p complex also protects the 3?-ends of mRNAs in vivo from trimming, presumably by binding to the 3?-ends. In order to determine the intrinsic RNA-binding properties of this complex, we have purified it from yeast and carried out in vitro analyses. Our studies revealed that it directly binds RNA at/near the 3?-end. Importantly, it possesses the intrinsic ability to distinguish between oligoadenylated and polyadenylated RNAs such that the former are bound with much higher affinity than the latter. These results indicate that the intrinsic RNA-binding characteristics of this complex form a critical determinant of its in vivo interactions and functions.

Chowdhury, Ashis; Mukhopadhyay, Jaba; Tharun, Sundaresan

2007-01-01

37

Identification of a structural requirement for thyroid Na +\\/I ? symporter (NIS) function from analysis of a mutation that causes human congenital hypothyroidism  

Microsoft Academic Search

Patients with congenital lack of I? transport do not accumulate I? in their thyroids, often resulting in severe hypothyroidism. A single amino acid substitution in the thyroid Na+\\/I? symporter (NIS), proline replacing threonine at position 354 (T354P), was recently identified as the cause of this condition in two independent patients [1, 2]. Here we report that the lack of I?

Orlie Levy; Christopher S Ginter; Antonio De la Vieja; Daniel Levy; Nancy Carrasco

1998-01-01

38

Intracellular anion fluorescence assay for sodium\\/iodide symporter substrates  

Microsoft Academic Search

The sodium\\/iodide symporter (NIS) is primarily responsible for iodide accumulation in the thyroid gland for the synthesis of thyroid hormones; however, it can also transport other lyotropic anions in the thyroid gland and nonthyroid tissues. Some NIS substrates have important physiological or clinical roles, and others are environmental contaminants with health-related consequences. The aim of this study was to assess

Julie Di Bernardo; Carmela Iosco; Kerry J. Rhoden

2011-01-01

39

Two glucose/xylose transporter genes from the yeast Candida intermedia: first molecular characterization of a yeast xylose-H+ symporter  

PubMed Central

Candida intermedia PYCC 4715 was previously shown to grow well on xylose and to transport this sugar by two different transport systems: high-capacity and low-affinity facilitated diffusion and a high-affinity xylose–proton symporter, both of which accept glucose as a substrate. Here we report the isolation of genes encoding both transporters, designated GXF1 (glucose/xylose facilitator 1) and GXS1 (glucose/xylose symporter 1) respectively. Although GXF1 was isolated by functional complementation of an HXT-null (where Hxt refers to hexose transporters) Saccharomyces cerevisiae strain, isolation of the GXS1 cDNA required partial purification and micro-sequencing of the transporter, identified by its relative abundance in cells grown on low xylose concentrations. Both genes were expressed in S. cerevisiae and the kinetic parameters of glucose and xylose transport were determined. Gxs1 is the first yeast xylose/glucose–H+ symporter to be characterized at the molecular level. Comparison of its amino acid sequence with available sequence data revealed the existence of a family of putative monosaccharide–H+ symporters encompassing proteins from several yeasts and filamentous fungi.

Leandro, Maria Jose; Goncalves, Paula; Spencer-Martins, Isabel

2006-01-01

40

Repressible cation-phosphate symporters in Neurospora crassa.  

PubMed Central

The filamentous fungus Neurospora crassa possesses two nonhomologous high-affinity phosphate permeases, PHO-4 and PHO-5. We have isolated separate null mutants of these permeases, allowing us to study the remaining active transporter in vivo in terms of phosphate uptake and sensitivity to inhibitors. The specificity for the cotransported cation differs for PHO-4 and PHO-5, suggesting that these permeases employ different mechanisms for phosphate translocation. Phosphate uptake by PHO-4 is stimulated 85-fold by the addition of Na+, which supports the idea that PHO-4 is a Na(+)-phosphate symporter. PHO-5 is unaffected by Na+ concentration but is much more sensitive to elevated pH than is PHO-4. Presumably, PHO-5 is a H(+)-phosphate symporter. Na(+)-coupled symport is usually associated with animal cells. The finding of such a system in a filamentous fungus is in harmony with the idea that the fungal and animal kingdoms are more closely related to each other than either is to the plant kingdom. Images Fig. 2

Versaw, W K; Metzenberg, R L

1995-01-01

41

Analysis of human sodium iodide symporter immunoreactivity in human exocrine glands.  

PubMed

The human sodium iodide symporter (hNIS) is an intrinsic transmembrane protein that mediates the active transport of iodide across the basolateral membrane of thyroid follicular cells. In addition to normally functioning thyroid tissue, various extrathyroidal tissues, including salivary gland, lacrimal gland, gastric mucosa, choroid plexus, and lactating mammary gland, have been demonstrated to accumulate iodide. After cloning and molecular characterization of the sodium iodide symporter, expression of hNIS messenger ribonucleic acid has been detected in a broad range of extrathyroidal tissues using Northern blot analysis and RT-PCR. In this study we used both monoclonal and polyclonal antibodies directed against different portions of hNIS protein together with a highly sensitive immunostaining technique to assess hNIS protein expression in tissue sections derived from normal human salivary and lacrimal glands, pancreas, as well as gastric and colonic mucosa. Immunohistochemical analysis of normal human salivary and lacrimal glands revealed marked hNIS immunoreactivity in ductal cells and less intense staining of acinar cells. Further, immunostaining of gastric and colonic mucosa showed marked hNIS immunoreactivity confined to chief and parietal cells in gastric mucosa and to epithelial cells lining mucosal crypts in colonic mucosa. In normal human pancreas, hNIS immunoreactivity was located in ductal cells, exocrine parenchymal cells, and Langerhans islet cells. In conclusion, our study demonstrates the expression of hNIS protein by several human exocrine glands, suggesting that iodide transport in these glands is a specific property conferred by the expression of hNIS protein, which may serve important functions by concentrating iodine in glandular secretions. PMID:10566669

Spitzweg, C; Joba, W; Schriever, K; Goellner, J R; Morris, J C; Heufelder, A E

1999-11-01

42

Sodium solute symporter and cadherin proteins act as Bacillus thuringiensis Cry3Ba toxin functional receptors in Tribolium castaneum.  

PubMed

Understanding how Bacillus thuringiensis (Bt) toxins interact with proteins in the midgut of susceptible coleopteran insects is crucial to fully explain the molecular bases of Bt specificity and insecticidal action. In this work, aminopeptidase N (TcAPN-I), E-cadherin (TcCad1), and sodium solute symporter (TcSSS) have been identified by ligand blot as putative Cry3Ba toxin-binding proteins in Tribolium castaneum (Tc) larvae. RNA interference knockdown of TcCad1 or TcSSS proteins resulted in decreased susceptibility to Cry3Ba toxin, demonstrating the Cry toxin receptor functionality for these proteins. In contrast, TcAPN-I silencing had no effect on Cry3Ba larval toxicity, suggesting that this protein is not relevant in the Cry3Ba toxin mode of action in Tc. Remarkable features of TcSSS protein were the presence of cadherin repeats in its amino acid sequence and that a TcSSS peptide fragment containing a sequence homologous to a binding epitope found in Manduca sexta and Tenebrio molitor Bt cadherin functional receptors enhanced Cry3Ba toxicity. This is the first time that the involvement of a sodium solute symporter protein as a Bt functional receptor has been demonstrated. The role of this novel receptor in Bt toxicity against coleopteran insects together with the lack of receptor functionality of aminopeptidase N proteins might account for some of the differences in toxin specificity between Lepidoptera and Coleoptera insect orders. PMID:23645668

Contreras, Estefanía; Schoppmeier, Michael; Real, M Dolores; Rausell, Carolina

2013-05-03

43

Sodium-coupled symports in the plasma membranes of plant cells.  

PubMed

It has been a dogma since the success of chemiosmotic theory that plants use protons as a membrane-coupling mechanism--it has come to be implied that they use no other ion for the purpose. Following the finding that potassium can be taken up by sodium symport in Chara australis, we have established that urea is also taken up by sodium symport in the same organism. use of electrical and flux methods for finding sodium-driven symport are described; using these methods, sodium symport is also found for three solutes in Nitella translucens. Extending the search to higher plants has shown indications of sodium-driven uptake of potassium in Elodea canadensis roots, and Egeria sp. and Vallisneria leaves. Sugar and potassium uptake in Zea mays roots, and sugar uptake in Elodea canadensis showed no sodium requirement. PMID:7597642

Walker, N A

1994-01-01

44

Modified Sodium Iodide Symporter Proteins and Genes for Imaging and Cancer Therapy.  

National Technical Information Service (NTIS)

The invention provides modified sodium iodide symporter (NIS) proteins, and polynucleotides encoding modified NIS proteins. The modified NIS proteins have a net electrostatic charge more positive than that of corresponding wild-type NIS proteins. Expressi...

D. H. Shen S. M. Jhiang X. Lin

2003-01-01

45

The Sodium Iodide Symporter (NIS): Regulation and Approaches to Targeting for Cancer Therapeutics  

PubMed Central

Expression of the sodium iodide symporter (NIS) is required for efficient iodide uptake in thyroid and lactating breast. Since most differentiated thyroid cancer expresses NIS, ?-emitting radioactive iodide is routinely utilized to target remnant thyroid cancer and metastasis after total thyroidectomy. Stimulation of NIS expression by high levels of thyroid-stimulating hormone is necessary to achieve radioiodide uptake into thyroid cancer that is sufficient for therapy. The majority of breast cancer also expresses NIS, but at a low level insufficient for radioiodine therapy. Retinoic acid is a potent NIS inducer in some breast cancer cells. NIS is also modestly expressed in some non-thyroidal tissues, including salivary glands, lacrimal glands and stomach. Selective induction of iodide uptake is required to target tumors with radioiodide. Iodide uptake in mammalian cells is dependent on the level of NIS gene expression, but also successful translocation of NIS to the cell membrane and correct insertion. The regulatory mechanisms of NIS expression and membrane insertion are regulated by signal transduction pathways that differ by tissue. Differential regulation of NIS confers selective induction of functional NIS in thyroid cancer cells, as well as some breast cancer cells, leading to more efficient radioiodide therapy for thyroid cancer and a new strategy for breast cancer therapy. The potential for systemic radioiodide treatment of a range of other cancers, that do not express endogenous NIS, has been demonstrated in models with tumor-selective introduction of exogenous NIS.

Kogai, Takahiko; Brent, Gregory A.

2012-01-01

46

Molecular characterization of the first aromatic nutrient transporter from the sodium neurotransmitter symporter family.  

PubMed

Nutrient amino acid transporters (NATs, subfamily of sodium neurotransmitter symporter family SNF, a.k.a. SLC6) represent a set of phylogenetically and functionally related transport proteins, which perform intracellular absorption of neutral, predominantly essential amino acids. Functions of NATs appear to be critical for the development and survival in organisms. However, mechanisms of specific and synergetic action of various NAT members in the amino acid transport network are virtually unexplored. A new transporter, agNAT8, was cloned from the malaria vector mosquito Anopheles gambiae (SS). Upon heterologous expression in Xenopus oocytes it performs high-capacity, sodium-coupled (2:1) uptake of nutrients with a strong preference for aromatic catechol-branched substrates, especially phenylalanine and its derivatives tyrosine and L-DOPA, but not catecholamines. It represents a previously unknown SNF phenotype, and also appears to be the first sodium-dependent B(0) type transporter with a narrow selectivity for essential precursors of catecholamine synthesis pathways. It is strongly and specifically transcribed in absorptive and secretory parts of the larval alimentary canal and specific populations of central and peripheral neurons of visual-, chemo- and mechano-sensory afferents. We have identified a new SNF transporter with previously unknown phenotype and showed its important role in the accumulation and redistribution of aromatic substrates. Our results strongly suggest that agNAT8 is an important, if not the major, provider of an essential catechol group in the synthesis of catecholamines for neurochemical signaling as well as ecdysozoan melanization and sclerotization pathways, which may include cuticle hardening/coloring, wound curing, oogenesis, immune responses and melanization of pathogens. PMID:16888066

Meleshkevitch, Ella A; Assis-Nascimento, Poincyane; Popova, Lyudmila B; Miller, Melissa M; Kohn, Andrea B; Phung, Elizabeth N; Mandal, Anita; Harvey, William R; Boudko, Dmitri Y

2006-08-01

47

Transport of cyclitols by a proton symport in Klebsiella aerogenes.  

PubMed

The respiration and the ATP content of Klebsiella aerogenes in the presence of various inhibitors were compared to the transport of scyllo-inositol. The ATPase was found to be inhibited by dicyclohexyl carbodiimide. The transport has been tested in anaerobiosis and aerobiosis. From the results obtained it is concluded that either ATP or respiration can sustain the transport activity in independent manner. 2. The energy derived from the respiratory chain reactions or the ATP hydrolysis results in electrogenic extrusion of protons. The electrochemical potential created drives the accumulation of scyllo-inositol, as shown by an increase of pH of the medium on addition of the substrate to cells in anaerobiosis. With non-induced cells no change in pH occurs, which demonstrates that proton flow is really linked to the transport. No H+/Na+ or K+ exchange is observed and the proton conductor carbonylcyanide m-chlorophenylhydrazone abolishes the pH shift caused by substrate addition. The stoichiometry of the symport H+/cyclitol is 1 and the half-maximum value of the pH variation as a function of the amount of scyllo-inositol added corresponds to a concentration of scyllo-inositol very close to the KT of influx. PMID:12979

Reber, G; Mermod, M; Deshusses, J

1977-01-01

48

Intracellular anion fluorescence assay for sodium/iodide symporter substrates.  

PubMed

The sodium/iodide symporter (NIS) is primarily responsible for iodide accumulation in the thyroid gland for the synthesis of thyroid hormones; however, it can also transport other lyotropic anions in the thyroid gland and nonthyroid tissues. Some NIS substrates have important physiological or clinical roles, and others are environmental contaminants with health-related consequences. The aim of this study was to assess the utility of a yellow fluorescent protein variant, YFP-H148Q/I152L, as a biosensor to monitor the cellular uptake of NIS substrates, including thiocyanate (SCN(-)), nitrate (NO(3)(-)), chlorate (ClO(3)(-)), perchlorate (ClO(4)(-)), and perrhenate (ReO(4)(-)). The fluorescence of purified YFP-H148Q/I152L was suppressed by anions with an order of potency of ReO(4)(-)>ClO(4)(-)=I(-)=SCN(-)=ClO(3)(-)>NO(3)(-)?Cl(-). Anions also suppressed the fluorescence of YFP-H148Q/I152L expressed in FRTL-5, a thyroid cell line with high NIS expression. Quantitation of intracellular concentrations revealed differences among anions in the affinity and maximal velocity of NIS-mediated uptake as well as in the rate constant for passive efflux. These results suggest that YFP-H148Q/I152L can serve as an intracellular biosensor of NIS-transported anions and may be useful to study the physiology of endogenous anions as well as the health-related consequences of environmental anions. PMID:21545783

Di Bernardo, Julie; Iosco, Carmela; Rhoden, Kerry J

2011-04-20

49

Sodium Iodide Symporter (NIS)-Mediated Radiovirotherapy for Pancreatic Cancer  

PubMed Central

OBJECTIVE We have previously shown the therapeutic efficacy of an engineered oncolytic measles virus expressing the sodium iodide symporter reporter gene (MV-NIS) in mice with human pancreatic cancer xenografts. The goal of this study was to determine the synergy between MV-NIS-induced oncolysis and NIS-mediated 131I radiotherapy in this tumor model. MATERIALS AND METHODS Subcutaneous human BxPC-3 pancreatic tumors were injected twice with MV-NIS. Viral infection, NIS expression, and intratumoral iodide uptake were quantitated with 123I micro-SPECT/CT. Mice with MV-NIS infected tumors were treated with 0, 37, or 74 MBq 131I and monitored for tumor progression and survival. Additional studies were performed with stable NIS-expressing tumors (BxPC-3-NIS) treated with 0, 3.7, 18.5, 37, or 74 MBq of 131I. RESULTS Mice treated with intratumoral MV-NIS exhibited significant tumor growth delay (p<0.01) and prolonged survival (p=0.02) compared with untreated mice. Synergy between MV-NIS-induced oncolysis and NIS-mediated 131I ablation was not seen; however, a significant correlation was observed between NIS-mediated intratumoral iodide localization (% ID/g) and peak tumor volume reduction (p=0.04) with combination MV-NIS and 131I therapy. Stably-transduced NIS-expressing BxPC-3 tumors exhibited rapid regression with ?18.5 MBq 131I. CONCLUSION Delivery of 131I radiotherapy to NIS-expressing tumors can be optimized using micro-SPECT/CT image guidance. Significant hurdles exist for NIS as a therapeutic gene for combined radiovirotherapy in this human pancreatic cancer model. The lack of synergy observed with MV-NIS and 131I in this model was not due to a lack of radiosensitivity, but rather to a non-uniform intratumoral distribution of MV-NIS infection.

Penheiter, Alan R.; Wegman, Troy R.; Classic, Kelly L.; Dingli, David; Bender, Claire E.; Russell, Stephen J.; Carlson, Stephanie K.

2011-01-01

50

Characterization of the proton/glutamate symport protein of Bacillus subtilis and its functional expression in Escherichia coli.  

PubMed Central

Transport of acidic amino acids in Bacillus subtilis is an electrogenic process in which L-glutamate or L-aspartate is symported with at least two protons. This is shown by studies of transport in membrane vesicles in which a proton motive force is generated by oxidation of ascorbate-phenazine methosulfate or by artificial ion gradients. An inwards-directed sodium gradient had no (stimulatory) effect on proton motive force-driven L-glutamate uptake. The transporter is specific for L-glutamate and L-aspartate. L-Glutamate transport is inhibited by beta-hydroxyaspartate and cysteic acid but not by alpha-methyl-glutamate. The gene encoding the L-glutamate transport protein of B. subtilis (gltPBsu) was cloned by complementation of Escherichia coli JC5412 for growth on glutamate as the sole source of carbon, energy, and nitrogen, and its nucleotide sequence was determined. Putative promoter, terminator, and ribosome binding site sequences were found in the flanking regions. UUG is most likely the start codon. gltPBsu encodes a polypeptide of 414 amino acid residues and is homologous to several proteins that transport glutamate and/or structurally related compounds such as aspartate, fumarate, malate, and succinate. Both sodium- and proton-coupled transporters belong to this family of dicarboxylate transporters. Hydropathy profiling and multiple alignment of the family of carboxylate transporters suggest that each of the proteins spans the cytoplasmic membrane 12 times with both the amino and carboxy termini on the inside.

Tolner, B; Ubbink-Kok, T; Poolman, B; Konings, W N

1995-01-01

51

Prodigiosins uncouple lysosomal vacuolar-type ATPase through promotion of H+/Cl- symport.  

PubMed Central

We reported previously [Kataoka, Muroi, Ohkuma, Waritani, Magae, Takatsuki, Kondo, Yamasaki and Nagai (1995) FEBS Lett. 359, 53-59] that prodigiosin 25-C (one of the red pigments of the prodigiosin group produced by micro-organisms like Streptomyces and Serratia) uncoupled vacuolar H+-ATPase, inhibited vacuolar acidification and affected glycoprotein processing. In the present study we show that prodigiosin, metacycloprodigiosin and prodigiosin 25-C, all raise intralysosomal pH through inhibition of lysosomal acidification driven by vacuolar-type (V-)ATPase without inhibiting ATP hydrolysis in a dose-dependent manner with IC50 values of 30-120 pmol/mg of protein. The inhibition against lysosomal acidification was quick and reversible, showing kinetics of simple non-competitive (for ATP) inhibition. However, the prodigiosins neither raised the internal pH of isolated lysosomes nor showed ionophoric activity against H+ or K+ at concentrations where they strongly inhibited lysosomal acidification. They required Cl- for their acidification inhibitory activity even when driven in the presence of K+ and valinomycin, suggesting that their target is not anion (chloride) channel(s). In fact, the prodigiosins inhibited acidification of proteoliposomes devoid of anion channels that were reconstituted from lysosomal vacuolar-type (V-)ATPase and Escherichia coli phospholipids. However, they did not inhibit the formation of an inside-positive membrane potential driven by lysosomal V-ATPase. Instead, they caused quick reversal of acidified pH driven by lysosomal V-ATPase and, in acidic buffer, produced quick acidification of lysosomal pH, both only in the presence of Cl-. In addition, they induced swelling of liposomes and erythrocytes in iso-osmotic ammonium salt of chloride but not of gluconate, suggesting the promotion of Cl- entry by prodigiosins. These results suggest that prodigiosins facilitate the symport of H+ with Cl- (or exchange of OH- with Cl-) through lysosomal membranes, resulting in uncoupling of vacuolar H+-ATPase.

Ohkuma, S; Sato, T; Okamoto, M; Matsuya, H; Arai, K; Kataoka, T; Nagai, K; Wasserman, H H

1998-01-01

52

Sodium/iodide symporter is expressed in the majority of seminomas and embryonal testicular carcinomas.  

PubMed

Testicular cancer is the most frequent cancer in young men. The large majority of patients have a good prognosis, but in a small group of tumors, the current treatments are not effective. Radioiodine is routinely used in the treatment of thyroid cancer and is currently investigated as a potential therapeutic tool even for extra-thyroid tumors able to concentrate this radioisotope. Expression of Na(+)/I(-) symporter (NIS (SLC5A5)), the glycoprotein responsible for iodide transport, has been demonstrated in normal testicular tissue. In this study, we analyzed NIS expression in a large series of testicular carcinomas. Our retrospective series included 107 patients operated for testicular tumors: 98 typical seminomas, six embryonal carcinomas, one mixed embryonal choriocarcinoma, and two Leydig cells tumors. Expression and regulation of NIS mRNA and protein levels were also investigated in human embryonal testicular carcinoma cells (NTERA) by real-time RT-PCR and western blotting respectively. Immunohistochemical analysis showed the presence of NIS in the large majority of seminomas (90/98) and embryonal carcinomas (5/7) of the testis but not in Leydig cell carcinomas. Expression of NIS protein was significantly associated with lymphovascular invasion. In NTERA cells treated with the histone deacetylase inhibitors SAHA and valproic acid, a significant increase in NIS mRNA (about 60- and 30-fold vs control, P<0.001 and P<0.01 respectively) and protein levels, resulting in enhanced ability to uptake radioiodine, was observed. Finally, NIS expression in testicular tumors with the more aggressive behavior is of interest for the potential use of targeting NIS to deliver radioiodine in malignant cells. PMID:23117572

Micali, S; Maggisano, V; Cesinaro, A; Celano, M; Territo, A; Reggiani Bonetti, L; Sponziello, M; Migaldi, M; Navarra, M; Bianchi, G; Filetti, S; Russo, D

2013-01-18

53

Sodium\\/iodide symporter: a key transport system in thyroid cancer cell metabolism  

Microsoft Academic Search

The recent cloning of the gene encoding the sodium\\/iodide symporter (NIS) has enabled better characterization of the molecular mechanisms underlying iodide transport, thus opening the way to clarifying its role in thyroid diseases. Several studies, at both the mRNA and the protein expression levels, have demonstrated that TSH, the primary regulator of iodide uptake, upregulates NIS gene expression and NIS

Sebastiano Filetti; Jean-Michel Bidart; Franco Arturi; Bernard Caillou; Diego Russo; Martin Schlumberger

1999-01-01

54

Distribution of Na + \\/I – Symporter in Thyroid Cancers in an Iodine-deficient Population: An Immunohistochemical Study  

Microsoft Academic Search

Background  There are significant differences in the prevalence and behavior of differentiated thyroid cancers (DTC) in the iodine-deficient\\u000a areas (IDA) and iodine-sufficient areas (ISA) of the world. The sodium iodide symporter (NIS), mediates active transport of\\u000a iodide across the basolateral aspect of the thyroid follicular cell. However, no study had specifically addressed the issue\\u000a of expression of sodium iodide symporter (NIS)

Anjali Mishra; Lily Pal; Saroj Kanta Mishra

2007-01-01

55

Establishment and Characterization of a Chinese Hamster Ovary Cell Line, CHO4J, Stably Expressing a Number of Na +\\/I ?Symporters  

Microsoft Academic Search

The cDNA of the Na+\\/I?symporter playing a key role in thyroid iodide transport was cloned very recently. To characterize its function, we transfected the Na+\\/I?symporter gene into Chinese hamster ovary (CHO) cells and established a cell line stably expressing a number of rat Na+\\/I?symporters, named CHO-4J. Iodide uptake was dependent on [Na+] and reached a plateau within 30 min. Kinetic

Shinji Kosugi; Norihito Sasaki; Noritaka Hai; Hideo Sugawa; Norihiko Aoki; Chiaki Shigemasa; Toru Mori; Akio Yoshida

1996-01-01

56

The crystal structure of a sodium galactose transporter reveals mechanistic insights into Na+/sugar symport  

PubMed Central

Membrane transporters that use energy stored in sodium gradients to drive nutrients into cells constitute a major class of proteins. We report the crystal structure of a member of the solute sodium symporters (SSS), the Vibrio parahaemolyticus sodium/galactose symporter (vSGLT). The ~3.0Å structure contains 14 transmembrane helices in an inward facing conformation with a core structure of inverted repeats of 5 TM helices (TM2-TM6 and TM7-TM11). Galactose is bound in the center of the core, occluded from the outside solutions by hydrophobic residues. Surprisingly, the architecture of the core is similar to the leucine transporter (LeuT) from a different gene family. Modeling the outward-facing conformation based on the LeuT structure, in conjunction with biophysical data, provides insight into structural rearrangements for active transport.

Faham, Salem; Watanabe, Akira; Besserer, Gabriel Mercado; Cascio, Duilio; Specht, Alexandre; Hirayama, Bruce A.; Wright, Ernest M.; Abramson, Jeff

2011-01-01

57

Relationship between the Na+/H+ antiporter and Na+/substrate symport in Bacillus alcalophilus.  

PubMed

The Na+/H+ antiporter of the obligate alkalophile Bacillus alcalophilus facilitates growth at alkaline pH and precludes growth below pH 8.5. Thus, nonalkalophilic mutant strains do not exhibit Na+/H+ antiport activity and, interestingly, such strains concomitantly lose the ability to catalyze Na+-dependent accumulation of alpha-aminoisobutyrate [Krulwich, T. A., Mandel, D. G. Bornstein, R. F. & Guffanti, A. A. (1979) Biochem. Biophys. Res. Commun. 91, 58-62]. Several other Na+-dependent transport systems are now documented in vesicles from the wild-type strain, and it is demonstrated that these systems are defective in vesicles from the nonalkalophilic mutant KM23. Surprisingly, the defect seems to result not from the loss of Na+/H+ antiport activity per se but from a pleiotropic defect in the Na+/substrate symporters themselves. Monensin, an ionophore that catalyzes Na+/H+ exchange, does not restore respiration-driven Na+/substrate symport in KM23 vesicles. Moreover, with KM23 vesicles, efflux of alpha-aminoisobutyrate, L-malate, and L-aspartate down their respective concentration gradients is not stimulated by Na+, in contrast to the observations with wild-type vesicles. Because monensin should ameliorate a simple defect in Na+/H+ antiport activity and the antiporter should not be required for Na+/substrate symport down a concentration gradient, the results suggest that there may be a direct relationship between the antiporter and various Na+/substrate symporters. One possibility is that the systems share a Na+-translocating subunit. PMID:6262805

Guffanti, A A; Cohn, D E; Kaback, H R; Krulwich, T A

1981-03-01

58

Regulation of the sodium iodide symporter by iodide in FRTL-5 cells  

Microsoft Academic Search

Objective: The acute decrease in iodide organification in the thyroid in response to excess iodide is termed the acute Wolff-Chaikoff effect and normal organification resumes in spite of continued high plasma iodide concentrations (escape from the acute Wolff-Chaikoff effect). We have recently reported that large doses of iodide given to rats chronically decrease the sodium\\/iodide symporter (NIS) mRNA and protein,

Peter H K Eng; Guemalli R Cardona; Michael C Previti; William W Chin; Lewis E Braverman

2001-01-01

59

Radioiodine therapy of colon cancer following tissue-specific sodium iodide symporter gene transfer  

Microsoft Academic Search

We investigated the feasibility of using radioiodine therapy in colon carcinoma cells (HCT 116) following tumor-specific expression of the human sodium iodide symporter (hNIS) using the carcinoembryonic antigen (CEA) promoter. HCT 116 cells were stably transfected with an expression vector, in which hNIS cDNA has been coupled to a CEA promoter fragment. This promoter is responsible for tissue-specific expression of

I V Scholz; N Cengic; C H Baker; K J Harrington; K Maletz; E R Bergert; R Vile; B Göke; J C Morris; C Spitzweg

2005-01-01

60

Radioiodine Therapy of Hepatoma Using Targeted Transfer of the Human Sodium\\/Iodide Symporter Gene  

Microsoft Academic Search

We investigated the feasibility of radioiodine therapy targeting hepatoma cells (MH3924A) by tissue-specific expression of the human sodium\\/iodide symporter (hNIS) gene directed by the murine albumin enhancer and promoter (mAlb). Methods: The cell-specific transcriptional activity of mAlb was examined by a luciferase assay in several transiently transfected cell lines. MH3924A cells were stably transfected with the recombinant retroviral vector, in

Libo Chen; Annette Altmann; Walter Mier; Helmut Eskerski; Karin Leotta; Lihe Guo; Ruisen Zhu; Uwe Haberkorn

2006-01-01

61

Structure and Molecular Mechanism of a Nucleobase-Cation-Symport-1 Family Transporter  

Microsoft Academic Search

The nucleobase-cation-symport-1 NCS1 transporters are essential components of salvage pathways for nucleobases and related metabolites. Here, we report the 2.85-angstrom resolution structure of the NCS1 benzyl-hydantoin transporter, Mhp1, from Microbacterium liquefaciens. Mhp1 contains 12 transmembrane helices, 10 of which are arranged in two inverted repeats of five helices. The structures of the outward-facing open and substrate-bound occluded conformations were solved,

Simone Weyand; Tatsuro Shimamura; Shunsuke Yajima; Shun'ichi Suzuki; Osman Mirza; Kuakarun Krusong; Elisabeth P. Carpenter; Nicholas G. Rutherford; Jonathan M. Hadden; John O'Reilly; Pikyee Ma; Massoud Saidijam; Simon G. Patching; Ryan J. Hope; Halina T. Norbertczak; Peter C. J. Roach; So Iwata; Peter J. F. Henderson; Alexander D. Cameron

2008-01-01

62

The Chlorella hexose/H+ symporter is a useful selectable marker and biochemical reagent when expressed in Volvox.  

PubMed

The multicellular obligately photoautotrophic alga Volvox is composed of only two types of cells, somatic and reproductive. Therefore, Volvox provides the simplest model system for the study of multicellularity. Metabolic labeling experiments using radioactive precursors are crucial for the detection of stage- and cell-type-specific proteins, glycoproteins, lipids, and carbohydrates. However, wild-type Volvox lacks import systems for sugars or amino acids. To circumvent this problem, the hexose/H+ symporter (HUP1) gene from the unicellular alga Chlorella was placed under the control of the constitutive Volvox beta-tubulin promoter. The corresponding transgenic Volvox strain synthesized the sugar transporter in a functional state and was able to efficiently incorporate 14C from labeled glucose or glucosamine. Sensitivity toward the toxic glucose/mannose analogue 2-deoxy-glucose increased by orders of magnitude in transformants. Thus we report the successful transformation of Volvox with a gene of heterologous origin. The chimeric gene may be selected for in either a positive or a negative manner, because transformants exhibit both prolonged survival in the dark in the presence of glucose and greatly increased sensitivity to the toxic sugar 2-deoxyglucose. The former trait may make the gene useful as a dominant selectable marker for use in transformation studies, whereas the latter trait may make it useful in development of a gene-targeting system. PMID:8570613

Hallmann, A; Sumper, M

1996-01-23

63

KT5823 Differentially Modulates Sodium Iodide Symporter Expression, Activity, and Glycosylation between Thyroid and Breast Cancer Cells  

PubMed Central

Na+/I? symporter (NIS)-mediated iodide uptake into thyroid follicular cells serves as the basis of radioiodine therapy for thyroid cancer. NIS protein is also expressed in the majority of breast tumors, raising potential for radionuclide therapy of breast cancer. KT5823, a staurosporine-related protein kinase inhibitor, has been shown to increase thyroid-stimulating hormone-induced NIS expression, and thus iodide uptake, in thyroid cells. In this study, we found that KT5823 does not increase but decreases iodide uptake within 0.5 h of treatment in trans-retinoic acid and hydrocortisone-treated MCF-7 breast cancer cells. Moreover, KT5823 accumulates hypoglycosylated NIS, and this effect is much more evident in breast cancer cells than thyroid cells. The hypoglycosylated NIS is core glycosylated, has not been processed through the Golgi apparatus, but is capable of trafficking to the cell surface. KT5823 impedes complex NIS glycosylation at a regulatory point similar to brefeldin A along the N-linked glycosylation pathway, rather than targeting a specific N-glycosylated site of NIS. KT5823-mediated effects on NIS activity and glycosylation are also observed in other breast cancer cells as well as human embryonic kidney cells expressing exogenous NIS. Taken together, KT5823 will serve as a valuable pharmacological reagent to uncover mechanisms underlying differential NIS regulation between thyroid and breast cancer cells at multiple levels.

Beyer, Sasha; Lakshmanan, Aparna; Liu, Yu-Yu; Zhang, Xiaoli; Wapnir, Irene; Smolenski, Albert

2011-01-01

64

Cloning of the mouse sodium iodide symporter and its expression in the mammary gland and other tissues.  

PubMed

Iodide concentration in milk by mammals is a necessary step for thyroid hormone synthesis by the newborn. With the purpose of using the mouse as an animal model to analyse the role of the sodium iodide symporter (NIS) in iodide transport and its regulation in the mammary gland, mouse NIS (mNIS) cDNA was isolated from lactating mice. The cloned sequence shows an open reading frame of 1854 nucleotides encoding a protein of 618 amino acids highly homologous to the rat and human NIS (95% and 81% identity respectively). Expression of mNIS in cultured mammalian cells induced cellular iodide accumulation. This iodide uptake process is sodium dependent and inhibited by thiocyanate and perchlorate. Tissue distribution analysis revealed that mNIS mRNAs are predominantly expressed in thyroid, stomach and in the lactating mammary gland and are present to a lower extent in several other tissues. Our data show for the first time that the level of mNIS mRNA is upregulated in the mammary gland during lactation. PMID:11431151

Perron, B; Rodriguez, A M; Leblanc, G; Pourcher, T

2001-07-01

65

Molecular Cloning and Functional Expression in Lactobacillus plantarum 80 of xylT, Encoding the d-Xylose-H+ Symporter of Lactobacillus brevis  

PubMed Central

A 3-kb region, located downstream of the Lactobacillus brevis xylA gene (encoding d-xylose isomerase), was cloned in Escherichia coli TG1. The sequence revealed two open reading frames which could code for the d-xylulose kinase gene (xylB) and another gene (xylT) encoding a protein of 457 amino acids with significant similarity to the d-xylose–H+ symporters of E. coli, XylE (57%), and Bacillus megaterium, XylT (58%), to the d-xylose–Na+ symporter of Tetragenococcus halophila, XylE (57%), and to the l-arabinose–H+ symporter of E. coli, AraE (60%). The L. brevis xylABT genes showed an arrangement similar to that of the B. megaterium xylABT operon and the T. halophila xylABE operon. Southern hybridization performed with the Lactobacillus pentosus xylR gene (encoding the d-xylose repressor protein) as a probe revealed the existence of a xylR homologue in L. brevis which is not located with the xyABT locus. The existence of a functional XylR was further suggested by the presence of xylO sequences upstream of xylA and xylT and by the requirement of d-xylose for the induction of d-xylose isomerase, d-xylulose kinase, and d-xylose transport activities in L. brevis. When L. brevis was cultivated in a mixture of d-glucose and d-xylose, the d-xylose isomerase and d-xylulose kinase activities were reduced fourfold and the d-xylose transport activity was reduced by sixfold, suggesting catabolite repression by d-glucose of d-xylose assimilation. The xylT gene was functionally expressed in Lactobacillus plantarum 80, a strain which lacks proton motive force-linked d-xylose transport activity. The role of the XylT protein was confirmed by the accumulation of d-xylose in L. plantarum 80 cells, and this accumulation was dependent on the proton motive force generated by either malolactic fermentation or by the metabolism of d-glucose. The apparent affinity constant of XylT for d-xylose was approximately 215 ?M, and the maximal initial velocity of transport was 35 nmol/min per mg (dry weight). Furthermore, of a number of sugars tested, only 6-deoxy-d-glucose inhibited the transport of d-xylose by XylT competitively, with a Ki of 220 ?M.

Chaillou, Stephane; Bor, Yeou-Cherng; Batt, Carl A.; Postma, Pieter W.; Pouwels, Peter H.

1998-01-01

66

A novel sucrose/H+ symport system and an intracellular sucrase in Leishmania donovani.  

PubMed

The flagellated form of pathogenic parasitic protozoa Leishmania, resides in the alimentary tract of its sandfly vector, where sucrose serves as a major nutrient source. In this study we report the presence of a sucrose transport system in Leishmania donovani promastigotes. The kinetics of sucrose uptake in promastigotes are biphasic in nature with both high affinity K(m) (K(m) of ? 75 ?M) and low affinity K(m) (K(m)? 1.38 mM) components. By contrast the virulent amastigotes take up sucrose via a low affinity process with a K(m) of 2.5mM. The transport of sucrose into promastigotes leads to rapid intracellular acidification, as indicated by changes in the fluorescence of the pH indicator 2',7'-bis-(2-carboxyethyl)-5-(6) Carboxyfluorescein (BCECF). In experiments with right side-out plasma membrane vesicles derived from L. donovani promastigotes, an artificial pH gradient was able to drive the active accumulation of sucrose. These data are consistent with the operation of a H(+)-sucrose symporter. The symporter was shown to be independent of Na(+) and to be insensitive to cytochalasin B, to the flavonoid phloretin and to the Na(+)/K(+) ATPase inhibitor ouabain. However, the protonophore carbonylcyanide P- (trifluromethoxy) phenylhydrazone (FCCP) and a number of thiol reagents caused significant inhibition of sucrose uptake. Evidence was also obtained for the presence of a stable intracellular pool of the sucrose splitting enzyme, sucrase, in promastigote stage parasites. The results are consistent with the hypothesis that L. donovani promastigotes take up sucrose via a novel H(+)-sucrose symport system and that, on entering the cell, the sucrose is hydrolysed to its component monosaccharides by an intracellular sucrase, thereby providing an energy source for the parasites. PMID:21515279

Singh, Arpita; Mandal, Debjani

2011-04-07

67

PI3K activation is associated with intracellular sodium/iodide symporter protein expression in breast cancer  

PubMed Central

Background The sodium/iodide symporter (NIS) is a membrane glycoprotein mediating active iodide uptake in the thyroid gland and is the molecular basis for radioiodide imaging and therapeutic ablation of thyroid carcinomas. NIS is expressed in the lactating mammary gland and in many human breast tumors, raising interest in similar use for diagnosis and treatment. However, few human breast tumors have clinically evident iodide uptake ability. We previously identified PI3K signaling as important in NIS upregulation in transgenic mouse models of breast cancer, and the PI3K pathway is commonly activated in human breast cancer. Methods NIS expression, subcellular localization, and function were analyzed in MCF-7 human breast cancer cells and MCF-7 cells stably or transiently expressing PI3K p110alpha subunit using Western blot of whole cell lysate, cell surface biotinylation Western blot and immunofluorescence, and radioiodide uptake assay, respectively. NIS localization was determined in a human breast cancer tissue microarray using immunohistochemical staining (IHC) and was correlated with pre-existing pAkt IHC data. Statistical analysis consisted of Student's t-test (in vitro studies) or Fisher's Exact Test (in vivo correlational studies). Results In this study, we demonstrate that PI3K activation in MCF-7 human mammary carcinoma cells leads to expression of underglycosylated NIS lacking cell surface trafficking necessary for iodide uptake ability. PI3K activation also appears to interfere with cell surface trafficking of exogenous NIS as well as all-trans retinoic acid-induced endogenous NIS. A correlation between NIS expression and upregulation of PI3K signaling was found in a human breast cancer tissue microarray. Conclusion Thus, the PI3K pathway likely plays a major role in the discordance between NIS expression and iodide uptake in breast cancer patients. Further study is warranted to realize the application of NIS-mediated radioiodide ablation in breast cancer.

Knostman, Katherine AB; McCubrey, James A; Morrison, Carl D; Zhang, Zhaoxia; Capen, Charles C; Jhiang, Sissy M

2007-01-01

68

Novel PSI domains in plant and animal H+-inositol symporters.  

PubMed

Inositols are indispensable components of cellular signaling molecules, and impaired cytoplasmic inositol concentrations affect cellular development. Although most cells can synthesize inositol de novo, plasma membrane-localized inositol uptake systems are indispensable for normal development. Here, we present in-depth functional analyses of plasma membrane-localized H(+)-inositol symporters from human and from the higher plant Arabidopsis thaliana. Sequence comparisons, structural and phylogenetic analyses revealed that these transporters possess conserved extracellular loop domains that represent homologs of plexins/semaphorin/integrin (PSI) domains from animal type I receptors. In these receptors, PSI domains modulate intracellular signaling via extracellular protein-protein interactions. Comparisons of H(+)-inositol symporters with wild type, mutated and truncated PSI domains in different expression systems showed that removal of the entire loop domain increased the V(max) of inositol uptake. Finally, we show that the PSI domains are targets for Ni(++) ions that cause a complete loss of transport activity. A possible role of Ni(++)-binding to PSI domains in Ni(++)-induced carcinogenicity is discussed. PMID:20230529

Dotzauer, Dorina; Wolfenstetter, Susanne; Eibert, Dorothee; Schneider, Sabine; Dietrich, Petra; Sauer, Norbert

2010-03-09

69

A Member of the Sugar Transporter Family, Stl1p Is the Glycerol/H+ Symporter in Saccharomyces cerevisiae  

PubMed Central

Glycerol and other polyols are used as osmoprotectants by many organisms. Several yeasts and other fungi can take up glycerol by proton symport. To identify genes involved in active glycerol uptake in Saccharomyces cerevisiae we screened a deletion mutant collection comprising 321 genes encoding proteins with 6 or more predicted transmembrane domains for impaired growth on glycerol medium. Deletion of STL1, which encodes a member of the sugar transporter family, eliminates active glycerol transport. Stl1p is present in the plasma membrane in S. cerevisiae during conditions where glycerol symport is functional. Both the Stl1 protein and the active glycerol transport are subject to glucose-induced inactivation, following identical patterns. Furthermore, the Stl1 protein and the glycerol symporter activity are strongly but transiently induced when cells are subjected to osmotic shock. STL1 was heterologously expressed in Schizosaccharomyces pombe, a yeast that does not contain its own active glycerol transport system. In S. pombe, STL1 conferred the ability to take up glycerol against a concentration gradient in a proton motive force-dependent manner. We conclude that the glycerol proton symporter in S. cerevisiae is encoded by STL1.

Ferreira, Celia; van Voorst, Frank; Martins, Antonio; Neves, Luisa; Oliveira, Rui; Kielland-Brandt, Morten C.; Lucas, Candida; Brandt, Anders

2005-01-01

70

Establishment and Characterization of a Breast Cancer Cell Line Expressing Na1\\/I2 Symporters for Radioiodide Concentrator Gene Therapy  

Microsoft Academic Search

131 I therapy for breast cancer, we established breast cancer cells stably expressing Na 1 \\/I 2 symporter (NIS) gene that can be modulated and studied in vitro and in vivo. Methods: We transfected rat NIS genes into a human breast cancer cell line (MCF7) by electropora- tion. Iodide accumulation was evaluated under various extracel- lular concentrations of sodium and

Yuji Nakamoto; Tsuneo Saga; Takashi Misaki; Hisataka Kobayashi; Noriko Sato; Takayoshi Ishimori; Shinji Kosugi; Harumi Sakahara; Junji Konishi

71

Structure and molecular mechanism of a nucleobase-cation-symport-1 family transporter  

PubMed Central

The ‘Nucleobase-Cation-Symport-1’, NCS1, transporters are essential components of salvage pathways for nucleobases and related metabolites. Here, we report the 2.85 Å resolution structure of the NCS1 benzyl-hydantoin transporter, Mhp1, from Microbacterium liquefaciens. Mhp1 contains 12 transmembrane helices, ten of which are arranged in two inverted repeats of 5 helices. The structures of the outward-facing open and substrate-bound occluded conformations were solved showing how the outward-facing cavity closes upon binding of substrate. Comparisons with the leucine (LeuTAa) and the galactose (vSGLT) transporters reveal that the outward- and inward-facing cavities are symmetrically arranged on opposite sides of the membrane. The reciprocal opening and closing of these cavities is synchronised by the inverted repeat helices 3 and 8, providing the structural basis of the ‘alternating access’ model for membrane transport.

Weyand, Simone; Shimamura, Tatsuro; Yajima, Shunsuke; Suzuki, Shun'ichi; Mirza, Osman; Krusong, Kuakarun; Carpenter, Elisabeth P.; Rutherford, Nicholas G.; Hadden, Jonathan M.; O'Reilly, John; Ma, Pikyee; Saidijam, Massoud; Patching, Simon G.; Hope, Ryan J.; Norbertczak, Halina T.; Roach, Peter C.J.; Iwata, So; Henderson, Peter J. F.; Cameron, Alexander D.

2010-01-01

72

Structure and molecular mechanism of a nucleobase-cation-symport-1 family transporter.  

PubMed

The nucleobase-cation-symport-1 (NCS1) transporters are essential components of salvage pathways for nucleobases and related metabolites. Here, we report the 2.85-angstrom resolution structure of the NCS1 benzyl-hydantoin transporter, Mhp1, from Microbacterium liquefaciens. Mhp1 contains 12 transmembrane helices, 10 of which are arranged in two inverted repeats of five helices. The structures of the outward-facing open and substrate-bound occluded conformations were solved, showing how the outward-facing cavity closes upon binding of substrate. Comparisons with the leucine transporter LeuT(Aa) and the galactose transporter vSGLT reveal that the outward- and inward-facing cavities are symmetrically arranged on opposite sides of the membrane. The reciprocal opening and closing of these cavities is synchronized by the inverted repeat helices 3 and 8, providing the structural basis of the alternating access model for membrane transport. PMID:18927357

Weyand, Simone; Shimamura, Tatsuro; Yajima, Shunsuke; Suzuki, Shun'ichi; Mirza, Osman; Krusong, Kuakarun; Carpenter, Elisabeth P; Rutherford, Nicholas G; Hadden, Jonathan M; O'Reilly, John; Ma, Pikyee; Saidijam, Massoud; Patching, Simon G; Hope, Ryan J; Norbertczak, Halina T; Roach, Peter C J; Iwata, So; Henderson, Peter J F; Cameron, Alexander D

2008-10-16

73

Cloning a Plant Amino Acid Transporter by Functional Complementation of a Yeast Amino Acid Transport Mutant  

Microsoft Academic Search

Amino acids are transported across the plasma membrane of plant cells by proton-amino acid symports. We report here the successful cloning of a neutral amino acid carrier by functional complementation. A histidine transport deletion mutant of Saccharomyces cerevisiae was transformed with an Arabidopsis thaliana cDNA library constructed in a yeast expression vector. Forty transformants, out of 10^5, allowed growth on

Li-Chu Hsu; Tzyy-Jen Chiou; Lishan Chen; Daniel R. Bush

1993-01-01

74

The crystal structure of a sodium galactose transporter reveals mechanistic insights into Na[superscript +]/sugar symport  

SciTech Connect

Membrane transporters that use energy stored in sodium gradients to drive nutrients into cells constitute a major class of proteins. We report the crystal structure of a member of the solute sodium symporters (SSS), the Vibrio parahaemolyticus sodium/galactose symporter (vSGLT). The -3.0 angstrom structure contains 14 transmembrane (TM) helices in an inward-facing conformation with a core structure of inverted repeats of 5 TM helices (TM2 to TM6 and TM7 to TM11). Galactose is bound in the center of the core, occluded from the outside solutions by hydrophobic residues. Surprisingly, the architecture of the core is similar to that of the leucine transporter (LeuT) from a different gene family. Modeling the outward-facing conformation based on the LeuT structure, in conjunction with biophysical data, provides insight into structural rearrangements for active transport.

Faham, S.; Watanabe, A.; Besserer, G.M.; Cascio, D.; Specht, A.; Hirayama, B.A.; Wright, E.M.; Abramson, J. (CNRS-UMR); (UCLA)

2009-08-27

75

Regulation by Thyroid-Stimulating Hormone of Sodium\\/Iodide Symporter Gene Expression and Protein Levels in FRTL-5 Cells  

Microsoft Academic Search

To investigate the mechanism of I2 transport stimulation by TSH, we studied the effects of TSH on Na1\\/I2 symporter (NIS) messenger RNA (mRNA) and protein levels in FRTL-5 cells and correlated these with I2 transport activity. When 1 mU\\/ml TSH was added to quies- cent FRTL-5 cells, a 12-h latency was observed before the onset of increased I2 transport activity,

TAKAHIKO KOGAI; TOYOSHI ENDO; TSUKASA SAITO; ASAKO MIYAZAKI; AKIO KAWAGUCHI; TOSHIMASA ONAYA

1997-01-01

76

Establishment of radioactive astatine and iodine uptake in cancer cell lines expressing the human sodium\\/iodide symporter  

Microsoft Academic Search

The sodium\\/iodide symporter (NIS) has been recognized as an attractive target for radioiodine-mediated cancer gene therapy. In this study we investigated the role of human NIS for cellular uptake of the high LET !-emitter astatine-211 (211At) in comparison with radioiodine as a potential radionuclide for future applications. A mammalian NIS expression vector was constructed and used to generate six stable

T. Petrich; H.-J. Helmeke; G. J. Meyer; W. H. Knapp; E. Pötter

2002-01-01

77

Quantitative Imaging of Na\\/I Symporter Transgene Expression Using Positron Emission Tomography in the Living Animal  

Microsoft Academic Search

Transgene expression can be measured in living animals by positron emission tomography (PET) using reporter genes associated with radiolabeled substrates or ligands. We examined here whether PET images obtained with a new reporter gene system (sodium\\/iodide symporter (NIS) and [124I]iodide) could provide quantitative information on gene expression in mice. Mice received various doses of recombinant adenovirus in which the expression

Thomas Groot-Wassink; Eric O. Aboagye; Yaohe Wang; Nicholas R. Lemoine; Andrew J. Reader; Georges Vassaux

2004-01-01

78

Targeting of tumor radioiodine therapy by expression of the sodium iodide symporter under control of the survivin promoter  

Microsoft Academic Search

To test the feasibility of using the survivin promoter to induce specific expression of sodium\\/iodide symporter (NIS) in cancer cell lines and tumors for targeted use of radionuclide therapy, a recombinant adenovirus, Ad-SUR-NIS, that expressed the NIS gene under control of the survivin promoter was constructed. Ad-SUR-NIS mediating iodide uptake and cytotoxicity was performed in vitro. Scintigraphic, biodistribution and radioiodine

R Huang; Z Zhao; X Ma; S Li; R Gong; A Kuang

2011-01-01

79

Ghrelin potentiates TSH-induced expression of the thyroid tissue-specific genes thyroglobulin, thyroperoxidase and sodium-iodine symporter, in rat PC-Cl3 Cells.  

PubMed

Ghrelin is a 28-amino-acid peptide that stimulates pituitary growth-hormone secretion and modulates food-intake and energy metabolism in mammals. It is mainly secreted by the stomach, but it is also expressed in many other tissues such as cartilage or the thyroid gland. In the present study we have analyzed by RT-PCR and using immunohistochemistry and immunofluorescence the expression and tissue distribution of ghrelin and its functional receptor (GHS-R type 1?) in thyroid cell-lines and in normal and pathological rat thyroid tissue. Additionally, by measuring the incorporation of BrdU, we have investigated if, as previously noted for FRTL-5 cells, ghrelin enhances the proliferation rate in the PC-Cl3 rat-thyrocyte cell-line. Finally, we have determined the stimulatory effect of ghrelin on TSH-induced expression of the tissue-specific key genes involved in the synthesis of thyroid hormone: thyroglobulin, thyroperoxidase and sodium-iodine symporter. Our data provide direct evidence that C-cell secreted ghrelin may be involved in the paracrine regulation of the thyroid follicular cell function. PMID:21945915

Morillo-Bernal, J; Fernández-Santos, J M; De Miguel, M; García-Marín, R; Gordillo-Martínez, F; Díaz-Parrado, E; Utrilla, J C; Martín-Lacave, I

2011-09-17

80

Structural basis for dynamic mechanism of proton-coupled symport by the peptide transporter POT.  

PubMed

Proton-dependent oligopeptide transporters (POTs) are major facilitator superfamily (MFS) proteins that mediate the uptake of peptides and peptide-like molecules, using the inwardly directed H(+) gradient across the membrane. The human POT family transporter peptide transporter 1 is present in the brush border membrane of the small intestine and is involved in the uptake of nutrient peptides and drug molecules such as ?-lactam antibiotics. Although previous studies have provided insight into the overall structure of the POT family transporters, the question of how transport is coupled to both peptide and H(+) binding remains unanswered. Here we report the high-resolution crystal structures of a bacterial POT family transporter, including its complex with a dipeptide analog, alafosfalin. These structures revealed the key mechanistic and functional roles for a conserved glutamate residue (Glu310) in the peptide binding site. Integrated structural, biochemical, and computational analyses suggested a mechanism for H(+)-coupled peptide symport in which protonated Glu310 first binds the carboxyl group of the peptide substrate. The deprotonation of Glu310 in the inward open state triggers the release of the bound peptide toward the intracellular space and salt bridge formation between Glu310 and Arg43 to induce the state transition to the occluded conformation. PMID:23798427

Doki, Shintaro; Kato, Hideaki E; Solcan, Nicolae; Iwaki, Masayo; Koyama, Michio; Hattori, Motoyuki; Iwase, Norihiko; Tsukazaki, Tomoya; Sugita, Yuji; Kandori, Hideki; Newstead, Simon; Ishitani, Ryuichiro; Nureki, Osamu

2013-06-24

81

A novel mechanism of sodium iodide symporter repression in differentiated thyroid cancer.  

PubMed

Differentiated thyroid cancers and their metastases frequently exhibit reduced iodide uptake, impacting on the efficacy of radioiodine ablation therapy. PTTG binding factor (PBF) is a proto-oncogene implicated in the pathogenesis of thyroid cancer. We recently reported that PBF inhibits iodide uptake, and have now elucidated a mechanism by which PBF directly modulates sodium iodide symporter (NIS) activity in vitro. In subcellular localisation studies, PBF overexpression resulted in the redistribution of NIS from the plasma membrane into intracellular vesicles, where it colocalised with the tetraspanin CD63. Cell-surface biotinylation assays confirmed a reduction in plasma membrane NIS expression following PBF transfection compared with vector-only treatment. Coimmunoprecipitation and GST-pull-down experiments demonstrated a direct interaction between NIS and PBF, the functional consequence of which was assessed using iodide-uptake studies in rat thyroid FRTL-5 cells. PBF repressed iodide uptake, whereas three deletion mutants, which did not localise within intracellular vesicles, lost the ability to inhibit NIS activity. In summary, we present an entirely novel mechanism by which the proto-oncogene PBF binds NIS and alters its subcellular localisation, thereby regulating its ability to uptake iodide. Given that PBF is overexpressed in thyroid cancer, these findings have profound implications for thyroid cancer ablation using radioiodine. PMID:19706688

Smith, Vicki E; Read, Martin L; Turnell, Andrew S; Watkins, Rachel J; Watkinson, John C; Lewy, Greg D; Fong, Jim C W; James, Sally R; Eggo, Margaret C; Boelaert, Kristien; Franklyn, Jayne A; McCabe, Christopher J

2009-08-25

82

Arabidopsis INOSITOL TRANSPORTER4 mediates high-affinity H+ symport of myoinositol across the plasma membrane.  

PubMed

Four genes of the Arabidopsis (Arabidopsis thaliana) monosaccharide transporter-like superfamily share significant homology with transporter genes previously identified in the common ice plant (Mesembryanthemum crystallinum), a model system for studies on salt tolerance of higher plants. These ice plant transporters had been discussed as tonoplast proteins catalyzing the inositol-dependent efflux of Na(+) ions from vacuoles. The subcellular localization and the physiological role of the homologous proteins in the glycophyte Arabidopsis were unclear. Here we describe Arabidopsis INOSITOL TRANSPORTER4 (AtINT4), the first member of this subgroup of Arabidopsis monosaccharide transporter-like transporters. Functional analyses of the protein in yeast (Saccharomyces cerevisiae) and Xenopus laevis oocytes characterize this protein as a highly specific H(+) symporter for myoinositol. These activities and analyses of the subcellular localization of an AtINT4 fusion protein in Arabidopsis and tobacco (Nicotiana tabacum) reveal that AtINT4 is located in the plasma membrane. AtINT4 promoter-reporter gene plants demonstrate that AtINT4 is strongly expressed in Arabidopsis pollen and phloem companion cells. The potential physiological role of AtINT4 is discussed. PMID:16603666

Schneider, Sabine; Schneidereit, Alexander; Konrad, Kai R; Hajirezaei, Mohammad-Reza; Gramann, Monika; Hedrich, Rainer; Sauer, Norbert

2006-04-07

83

Mammary radioiodine accumulation due to functional sodium iodide symporter expression in a benign fibroadenoma  

SciTech Connect

The sodium iodide symporter (NIS) has been characterized to mediate the active transport of iodide not only in the thyroid gland but also in various non-thyroidal tissues, including lactating mammary gland and the majority of breast cancers, thereby offering the possibility of diagnostic and therapeutic radioiodine application in breast cancer. In this report, we present a 57-year-old patient with multifocal papillary thyroid carcinoma, who showed focal radioiodine accumulation in a lesion in the right breast on a posttherapy {sup 131}I scan following radioiodine therapy. CT and MR-mammography showed a focal solid lesion in the right breast suggestive of a fibroadenoma, which was confirmed by histological examination. Immunostaining of paraffin-embedded tumor tissue sections using a human NIS antibody demonstrated NIS-specific immunoreactivity confined to epithelial cells of mammary ducts. In conclusion, in a thyroid cancer patient we identified a benign fibroadenoma of the breast expressing high levels of functionally active NIS protein as underlying cause of focal mammary radioiodine accumulation on a posttherapy {sup 131}I scan. These data show for the first time that functional NIS expression is not restricted to lactating mammary gland and malignant breast tissue, but can also be detected in benign breast lesions, such as fibroadenomata of the breast.

Berger, F. [Department of Nuclear Medicine, Ludwig-Maximilians-University, Munich (Germany); Unterholzner, S. [Department of Internal Medicine II, Klinikum Grosshadern, Marchioninistrasse 15, 81377 Munich, Ludwig-Maximilians-University, Munich (Germany); Diebold, J. [Department of Pathology, Ludwig-Maximilians-University, Munich (Germany); Knesewitsch, P. [Department of Nuclear Medicine, Ludwig-Maximilians-University, Munich (Germany); Hahn, K. [Department of Nuclear Medicine, Ludwig-Maximilians-University, Munich (Germany); Spitzweg, C. [Department of Internal Medicine II, Klinikum Grosshadern, Marchioninistrasse 15, 81377 Munich, Ludwig-Maximilians-University, Munich (Germany)]. E-mail: Christine.Spitzweg@med.uni-muenchen.de

2006-11-03

84

Substrate specificity and ion coupling in the Na+/betaine symporter BetP  

PubMed Central

BetP is an Na+-coupled betaine-specific transporter of the betaine–choline–carnitine (BCC) transporter family involved in the response to hyperosmotic stress. The crystal structure of BetP revealed an overall fold of two inverted structurally related repeats (LeuT-fold) that BetP shares with other sequence-unrelated Na+-coupled symporters. Numerous structures of LeuT-fold transporters in distinct conformational states have contributed substantially to our understanding of the alternating access mechanism of transport. Nevertheless, coupling of substrate and co-transported ion fluxes has not been structurally corroborated to the same extent. We converted BetP by a single-point mutation—glycine to aspartate—into an H+-coupled choline-specific transporter and solved the crystal structure of this mutant in complex with choline. The structure of BetP-G153D demonstrates a new inward-facing open conformation for BetP. Choline binding to a location close to the second, low-affinity sodium-binding site (Na2) of LeuT-fold transporters is facilitated by the introduced aspartate. Our data confirm the importance of a cation-binding site in BetP, playing a key role in a proposed molecular mechanism of Na+ and H+ coupling in BCC transporters.

Perez, Camilo; Koshy, Caroline; Ressl, Susanne; Nicklisch, Sascha; Kramer, Reinhard; Ziegler, Christine

2011-01-01

85

Proton-driven sucrose symport and antiport are provided by the vacuolar transporters SUC4 and TMT1/2.  

PubMed

The vacuolar membrane is involved in solute uptake into and release from the vacuole, which is the largest plant organelle. In addition to inorganic ions and metabolites, large quantities of protons and sugars are shuttled across this membrane. Current models suggest that the proton gradient across the membrane drives the accumulation and/or release of sugars. Recent studies have associated AtSUC4 with the vacuolar membrane. Some members of the SUC family are plasma membrane proton/sucrose symporters. In addition, the sugar transporters TMT1 and TMT2, which are localized to the vacuolar membrane, have been suggested to function in proton-driven glucose antiport. Here we used the patch-clamp technique to monitor carrier-mediated sucrose transport by AtSUC4 and AtTMTs in intact Arabidopsis thaliana mesophyll vacuoles. In the whole-vacuole configuration with wild-type material, cytosolic sucrose-induced proton currents were associated with a proton/sucrose antiport mechanism. To identify the related transporter on one hand, and to enable the recording of symporter-mediated currents on the other hand, we electrophysiologically characterized vacuolar proteins recognized by Arabidopsis mutants of partially impaired sugar compartmentation. To our surprise, the intrinsic sucrose/proton antiporter activity was greatly reduced when vacuoles were isolated from plants lacking the monosaccharide transporter AtTMT1/TMT2. Transient expression of AtSUC4 in this mutant background resulted in proton/sucrose symport activity. From these studies, we conclude that, in the natural environment within the Arabidopsis cell, AtSUC4 most likely catalyses proton-coupled sucrose export from the vacuole. However, TMT1/2 probably represents a proton-coupled antiporter capable of high-capacity loading of glucose and sucrose into the vacuole. PMID:21668536

Schulz, Alexander; Beyhl, Diana; Marten, Irene; Wormit, Alexandra; Neuhaus, Ekkehard; Poschet, Gernot; Büttner, Michael; Schneider, Sabine; Sauer, Norbert; Hedrich, Rainer

2011-07-27

86

Structural asymmetry in a trimeric Na+/betaine symporter, BetP, from Corynebacterium glutamicum.  

PubMed

The Na(+)-coupled symporter BetP catalyzes the uptake of the compatible solute betaine in the soil bacterium Corynebacterium glutamicum. BetP also senses hyperosmotic stress and regulates its own activity in response to stress level. We determined a three-dimensional (3D) map (at 8 Å in-plane resolution) of a constitutively active mutant of BetP in a C. glutamicum membrane environment by electron cryomicroscopy of two-dimensional crystals. The map shows that the constitutively active mutant, which lacks the C-terminal domain involved in osmosensing, is trimeric like wild-type BetP. Recently, we reported the X-ray crystal structure of BetP at 3.35 Å, in which all three protomers displayed a substrate-occluded state. Rigid-body fitting of this trimeric structure to the 3D map identified the periplasmic and cytoplasmic sides of the membrane. Fitting of an X-ray monomer to the individual protomer maps allowed assignment of transmembrane helices and of the substrate pathway, and revealed differences in trimer architecture from the X-ray structure in the tilt angle of each protomer with respect to the membrane. The three protomer maps showed pronounced differences around the substrate pathway, suggesting three different conformations within the same trimer. Two of those protomer maps closely match those of the atomic structures of the outward-facing and inward-facing states of the hydantoin transporter Mhp1, suggesting that the BetP protomer conformations reflect key states of the transport cycle. Thus, the asymmetry in the two-dimensional maps may reflect cooperativity of conformational changes within the BetP trimer, which potentially increases the rate of glycine betaine uptake. PMID:21281647

Tsai, Ching-Ju; Khafizov, Kamil; Hakulinen, Jonna; Forrest, Lucy R; Forrest, Lucy R; Krämer, Reinhard; Kühlbrandt, Werner; Ziegler, Christine

2011-01-31

87

Alpha-fetoprotein promoter-targeted sodium iodide symporter gene therapy of hepatocellular carcinoma.  

PubMed

Due to limited treatment options the prognosis of patients with advanced hepatocellular cancer (HCC) has remained poor. To investigate an alternative therapeutic approach, we examined the feasibility of radioiodine therapy of HCC following human sodium iodide symporter (NIS) gene transfer using a mouse alpha-fetoprotein (AFP) promoter construct to target NIS expression to HCC cells. For this purpose, the murine Hepa 1-6 and the human HepG2 hepatoma cell lines were stably transfected with NIS cDNA under the control of the tumor-specific AFP promoter. The stably transfected Hepa 1-6 cell line showed a 10-fold increase in iodide accumulation, while HepG2 cells accumulated (125)I approximately 60-fold. Tumor-specific NIS expression was confirmed on mRNA level by northern blot analysis, and on protein level by immunostaining, that revealed primarily membrane-associated NIS-specific immunoreactivity. In an in vitro clonogenic assay up to 78% of NIS-transfected Hepa 1-6 and 93% of HepG2 cells were killed by (131)I exposure, while up to 96% of control cells survived. In vivo NIS-transfected HepG2 xenografts accumulated 15% of the total (123)I administered per gram tumor with a biological half-life of 8.38 h, resulting in a tumor absorbed dose of 171 mGy MBq(-1) (131)I. After administration of a therapeutic (131)I dose (55.5 MBq) tumor growth of NIS expressing HepG2 xenografts was significantly inhibited. In conclusion, tumor-specific iodide accumulation was induced in HCC cells by AFP promoter-directed NIS expression in vitro and in vivo, which was sufficiently high to allow a therapeutic effect of (131)I. This study demonstrates the potential of tumor-specific NIS gene therapy as an innovative treatment strategy for HCC. PMID:17989705

Willhauck, M J; Sharif Samani, B R; Klutz, K; Cengic, N; Wolf, I; Mohr, L; Geissler, M; Senekowitsch-Schmidtke, R; Göke, B; Morris, J C; Spitzweg, C

2007-11-08

88

Radioiodine therapy of colon cancer following tissue-specific sodium iodide symporter gene transfer.  

PubMed

We investigated the feasibility of using radioiodine therapy in colon carcinoma cells (HCT 116) following tumor-specific expression of the human sodium iodide symporter (hNIS) using the carcinoembryonic antigen (CEA) promoter. HCT 116 cells were stably transfected with an expression vector, in which hNIS cDNA has been coupled to a CEA promoter fragment. This promoter is responsible for tissue-specific expression of CEA in gastrointestinal tract epithelium, and has been shown to target therapeutic genes to colorectal cancer cells. Functional NIS expression was confirmed by iodide uptake assay, Western blot analysis, immunostaining and in vitro clonogenic assay. The stably transfected HCT 116 cells concentrated (125)I about 10-fold in vitro without evidence of iodide organification. In contrast, transfection of control cancer cells without CEA expression did not result in iodide accumulation. Western blot analysis using a hNIS-specific antibody revealed a band of approximately 90 kDa. In addition, immunostaining of stably transfected HCT 116 cells revealed hNIS-specific membrane-associated immunoreactivity. In an in vitro clonogenic assay approximately 95% of stably transfected HCT 116 cells were killed by exposure to (131)I, while only about 5% of NIS-negative control cells were killed. Further, using an adenovirus carrying the NIS gene linked to the CEA promoter, high levels of tumor-specific radioiodide accumulation were induced in HCT 116 cells. In conclusion, a therapeutic effect of (131)I has been demonstrated in colon carcinoma cells following induction of tumor-specific iodide uptake activity by CEA promoter-directed NIS expression in vitro. This study demonstrates the potential of NIS as a therapeutic gene allowing radioiodine therapy of colon cancer following tumor-specific NIS gene transfer. PMID:15510175

Scholz, I V; Cengic, N; Baker, C H; Harrington, K J; Maletz, K; Bergert, E R; Vile, R; Göke, B; Morris, J C; Spitzweg, C

2005-02-01

89

Sodium-iodide symporter mediates iodide secretion in rat gastric mucosa in vitro.  

PubMed

In vivo studies on rats have demonstrated that considerable amounts of iodide are transported from the bloodstream into the gastric lumen. The mechanisms for and functional significance of this transport are poorly understood. Active (driven by Na(+)/K(+)-ATPase) iodide transport into thyroid follicular cells is mediated by the sodium-iodide symporter (NIS), which is also abundantly expressed in gastric mucosa. We aimed to further investigate the iodide transport in gastric mucosa and the possible role of NIS in this transport process. Iodide transport in rat gastric mucosa was studied in vitro in an Ussing chamber system using (125)I as a marker. The system allows measurements in both directions over a mucosal specimen. A considerable transport of iodide (from the serosal to the mucosal side) was established across the gastric mucosa, whereas in the opposite direction (mucosa to serosa), iodide transport was negligible. Sodium perchlorate (NaClO(4)), a competitive inhibitor of NIS, and ouabain, an inhibitor of the Na(+)/K(+)-ATPase, both attenuated gastric iodide transport from the serosal to the mucosal side. To investigate a possible neuroendocrine regulation of the iodide transport identified to occur from the serosal to the mucosal side of the stomach, thyroid-stimulating hormone (TSH), thyrotropin-releasing hormone (TRH), vasoactive intestinal peptide (VIP), histamine, or nitric oxide donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP) was added. None of these substances influenced the iodide transport. We conclude that iodide is actively transported into the gastric lumen and that this transport is at least partly mediated by NIS. Additional investigations are needed to understand the regulation and significance of this transport. PMID:16514173

Josefsson, Malin; Evilevitch, Lena; Weström, Björn; Grunditz, Torsten; Ekblad, Eva

2006-03-01

90

Congenital hypothyroidism due to mutations in the sodium/iodide symporter. Identification of a nonsense mutation producing a downstream cryptic 3' splice site.  

PubMed Central

A 12-yr-old hypothyroid girl was diagnosed at birth as athyreotic because her thyroid gland could not be visualized by isotope scanning. Goiter development due to incomplete thyrotropin suppression, a thyroidal radioiodide uptake of < 1%, and a low saliva to plasma ratio of 2.5 suggested iodide (I-) transport defect. mRNA isolated from her thyroid gland and injected into Xenopus oocytes failed to increase I- transport. Sequencing of the entire Na+/I- symporter (NIS) cDNA revealed a C to G transversion of nucleotide (nt) 1146 in exon 6, resulting in a Gln 267 (CAG) to Glu (GAG) substitution. This missense mutation produces an NIS with undetectable I- transport activity when expressed in COS-7 cells. Although only this missense mutation was identified in thyroid and lymphocyte cDNA, genotyping revealed that the proposita and her unaffected brother and father were heterozygous for this mutation. However, amplification of cDNA with a primer specific for the wild-type nt 1146 yielded a sequence lacking 67 nt. Genomic DNA showed a C to G transversion of nt 1940, producing a stop codon as well as a new downstream cryptic 3' splice acceptor site in exon 13, responsible for the 67 nt deletion, frameshift, and premature stop predicting an NIS lacking 129 carboxy-terminal amino acids. This mutation was inherited from the mother and present in the unaffected sister. Thus, although the proposita is a compound heterozygote, because of the very low expression (< 2.5%) of one mutant allele, she is functionally hemizygous for an NIS without detectable bioactivity.

Pohlenz, J; Rosenthal, I M; Weiss, R E; Jhiang, S M; Burant, C; Refetoff, S

1998-01-01

91

Regulation of Sodium Iodide Symporter Gene Expression by Rac1/p38? Mitogen-activated Protein Kinase Signaling Pathway in MCF-7 Breast Cancer Cells*  

PubMed Central

Activation of p38 MAPK is a key pathway for cell proliferation and differentiation in breast cancer and thyroid cells. The sodium/iodide symporter (NIS) concentrates iodide in the thyroid and lactating breast. All-trans-retinoic acid (tRA) markedly induces NIS activity in some breast cancer cell lines and promotes uptake of ?-emitting radioiodide 131I sufficient for targeted cytotoxicity. To identify a signal transduction pathway that selectively stimulates NIS expression, we investigated regulation by the Rac1-p38 signaling pathway in MCF-7 breast cancer cells and compared it with regulation in FRTL-5 rat thyroid cells. Loss of function experiments with pharmacologic inhibitors and small interfering RNA, as well as RT-PCR analysis of p38 isoforms, demonstrated the requirement of Rac1, MAPK kinase 3B, and p38? for the full expression of NIS in MCF-7 cells. In contrast, p38? was critical for NIS expression in FRTL-5 cells. Treatment with tRA or overexpression of Rac1 induced the phosphorylation of p38 isoforms, including p38?. A dominant negative mutant of Rac1 abolished tRA-induced phosphorylation in MCF-7 cells. Overexpression of p38? or Rac1 significantly enhanced (1.9- and 3.9-fold, respectively), the tRA-stimulated NIS expression in MCF-7 cells. This study demonstrates differential regulation of NIS by distinct p38 isoforms in breast cancer cells and thyroid cells. Targeting isoform-selective activation of p38 may enhance NIS induction, resulting in higher efficacy of 131I concentration and treatment of breast cancer.

Kogai, Takahiko; Liu, Yan-Yun; Mody, Kaizeen; Shamsian, Deborah V.; Brent, Gregory A.

2012-01-01

92

Regulation of sodium iodide symporter gene expression by Rac1/p38? mitogen-activated protein kinase signaling pathway in MCF-7 breast cancer cells.  

PubMed

Activation of p38 MAPK is a key pathway for cell proliferation and differentiation in breast cancer and thyroid cells. The sodium/iodide symporter (NIS) concentrates iodide in the thyroid and lactating breast. All-trans-retinoic acid (tRA) markedly induces NIS activity in some breast cancer cell lines and promotes uptake of ?-emitting radioiodide (131)I sufficient for targeted cytotoxicity. To identify a signal transduction pathway that selectively stimulates NIS expression, we investigated regulation by the Rac1-p38 signaling pathway in MCF-7 breast cancer cells and compared it with regulation in FRTL-5 rat thyroid cells. Loss of function experiments with pharmacologic inhibitors and small interfering RNA, as well as RT-PCR analysis of p38 isoforms, demonstrated the requirement of Rac1, MAPK kinase 3B, and p38? for the full expression of NIS in MCF-7 cells. In contrast, p38? was critical for NIS expression in FRTL-5 cells. Treatment with tRA or overexpression of Rac1 induced the phosphorylation of p38 isoforms, including p38?. A dominant negative mutant of Rac1 abolished tRA-induced phosphorylation in MCF-7 cells. Overexpression of p38? or Rac1 significantly enhanced (1.9- and 3.9-fold, respectively), the tRA-stimulated NIS expression in MCF-7 cells. This study demonstrates differential regulation of NIS by distinct p38 isoforms in breast cancer cells and thyroid cells. Targeting isoform-selective activation of p38 may enhance NIS induction, resulting in higher efficacy of (131)I concentration and treatment of breast cancer. PMID:22157753

Kogai, Takahiko; Liu, Yan-Yun; Mody, Kaizeen; Shamsian, Deborah V; Brent, Gregory A

2011-12-08

93

Cloning and functional characterization of LjPLT4, a plasma membrane xylitol H(+)- symporter from Lotus japonicus.  

PubMed

Polyols are compounds that play various physiological roles in plants. Here we present the identification of four cDNA clones of the model legume Lotus japonicus, encoding proteins of the monosaccharide transporter-like (MST) superfamily that share significant homology with previously characterized polyol transporters (PLTs). One of the transporters, named LjPLT4, was characterized functionally after expression in yeast. Transport assays revealed that LjPLT4 is a xylitol-specific H(+)-symporter (K (m), 0.34 mM). In contrast to the previously characterized homologues, LjPLT4 was unable to transport other polyols, including mannitol, sorbitol, myo-inositol and galactitol, or any of the monosaccharides tested. Interestingly, some monosaccharides, including fructose and xylose, inhibited xylitol uptake, although no significant uptake of these compounds was detected in the LjPLT4 transformed yeast cells, suggesting interactions with the xylitol binding site. Subcellular localization of LjPLT4-eYFP fusions expressed in Arabidopsis leaf epidermal cells indicated that LjPLT4 is localized in the plasma membrane. Real-time RT-PCR revealed that LjPLT4 is expressed in all major plant organs, with maximum transcript accumulation in leaves correlating with maximum xylitol levels there, as determined by GC-MS. Thus, LjPLT4 is the first plasma membrane xylitol-specific H(+)-symporter to be characterized in plants. PMID:21219252

Kalliampakou, Katerina I; Kouri, Evangelia D; Boleti, Haralabia; Pavli, Ourania; Maurousset, Laurence; Udvardi, Michael K; Katinakis, Panagiotis; Lemoine, Rémi; Flemetakis, Emmanouil

2011-01-01

94

Projection structure of the secondary citrate/sodium symporter CitS at 6 Å resolution by electron crystallography.  

PubMed

CitS from Klebsiella pneumoniae acts as a secondary symporter of citrate and sodium ions across the inner membrane of the host. The protein is the best characterized member of the 2-hydroxycarboxylate transporter family, while no experimental structural information at sub-nanometer resolution is available on this class of membrane proteins. Here, we applied electron crystallography to two-dimensional crystals of CitS. Carbon-film-adsorbed tubular two-dimensional crystals were studied by cryo-electron microscopy, producing the 6-Å-resolution projection structure of the membrane-embedded protein. In the p22(1)2(1)-symmetrized projection map, the predicted dimeric structure is clearly visible. Each monomeric unit can tentatively be interpreted as being composed of 11 transmembrane ?-helices. In projection, CitS shows a high degree of structural similarity to NhaP1, the Na(+)/H(+) antiporter of Methanococcus jannaschii. We discuss possible locations for the dimer interface and models for the helical arrangements and domain organizations of the symporter based on existing models. PMID:22349493

Kebbel, Fabian; Kurz, Mareike; Grütter, Markus G; Stahlberg, Henning

2012-02-17

95

Linkage of Familial Euthyroid Goiter to the Multinodular Goiter1 Locus and Exclusion of the Candidate Genes Thyroglobulin, Thyroperoxidase, and Na1\\/I2 Symporter  

Microsoft Academic Search

Iodine deficiency is the most important etiological factor for eu- thyroid endemic goiter. However, family and twin pair studies also indicate a genetic predisposition for euthyroid simple goiter. In hy- pothyroid goiters several molecular defects in the thyroglobulin (TG), thyroperoxidase (TPO), and Na1\\/I2 symporter (NIS) genes have been identified. The TSH receptor with its central role for thyroid function and

SUSANNE NEUMANN; HELMUT WILLGERODT; FRANK ACKERMANN; ANDREAS RESKE; MARTIN JUNG; RALF PASCHKE

96

The Expression of the Sodium\\/Iodide Symporter Is Up-Regulated in the Thyroid of Fetuses of Iodine Deficient Rats  

Microsoft Academic Search

Is the fetal thyroid already capable to increase its iodide up- take in response to iodine deficiency? To answer this question, we analyzed the expression of the Na\\/I symporter and sev- eral other genes in the thyroid of rat fetuses at 21 d of gestation from control mothers presenting a mild or more severe iodine deficiency. Female rats were placed

JANNY P. SCHRODER-VAN DER ELST; DAAN VAN DER HEIDE; JAN KASTELIJN; BERNARD ROUSSET; MARIA JESUS OBREGON

2010-01-01

97

A Probasin Promoter, Conditionally Replicating Adenovirus that Expresses the Sodium Iodide Symporter (NIS) for Radiovirotherapy of Prostate Cancer  

PubMed Central

The sodium iodide symporter (NIS) directs the uptake and concentration of iodide in thyroid cells. We have extended the use of NIS-mediated radioiodine therapy to other types of cancer, we transferred and expressed the sodium-iodide symporter (NIS) gene into prostate, colon, and breast cancer cells using adenoviral vectors. To improve vector efficiency we have developed a conditionally replicating adenovirus (CRAd) in which the E1a gene is driven by the prostate specific promoter, Probasin and the cassette RSV promoter-human NIScDNA-bGH polyA replaces the E3 region (CRAd Ad5PB_RSV-NIS). In vitro infection of the prostate cancer cell line LnCaP resulted in virus replication, cytolysis, and release of infective viral particles. Conversely, the prostate cancer cell line PC-3 (androgen receptor negative) and the pancreatic cancer cell line Panc-1 were refractory to the viral cytopathic effect and did not support viral replication. Radioiodine uptake was readily measurable in LnCaP cells infected with Ad5PB_RSV-NIS 24 hours post-infection, confirming NIS expression. In vivo, LnCaP tumor xenografts in nude mice injected intratumorally with Ad5PB_RSV_NIS CRAd expressed NIS actively as evidenced by 99Tc uptake and imaging. Administration of therapeutic 131I after virus injection significantly increased survival probability in mice carrying xenografted LnCaP tumors compared to virotherapy alone. The data indicate that Ad5PB_RSV_NIS replication is stringently restricted to androgen positive prostate cancer cells and results in effective NIS expression and uptake of radioiodine. This construct may allow multimodal therapy, combining cytolytic virotherapy with radioiodine treatment, to be developed as a novel treatment for prostate cancer.

Trujillo, Miguel A.; Oneal, Michael J.; McDonough, Samantha; Qin, Rui; Morris, John C.

2010-01-01

98

Kinetics Analysis of the Plasma Membrane Sucrose-H+ Symporter from Sugar Beet (Beta vulgaris L.) Leaves.  

PubMed Central

The kinetics behavior of the H+-sucrose (Suc) symporter was investigated in plasma membrane vesicles from sugar beet (Beta vulgaris L.) leaves by analyzing the effect of external and internal pH (pHo and pHi, respectively) on Suc uptake. The apparent Km for Suc uptake increased 18-fold as the pHo increased from 5.5 to 7.5. Over this same pHo range, the apparent Vmax for Suc uptake remained constant. The effects of pHi in the presence or absence of internal Suc were exclusively restricted to changes in Vmax. Thus, proton concentration on the inside of the membrane vesicles ([H+]i) behaved as a noncompetitive inhibitor of Suc uptake. The Km for the proton concentration on the outside of the membrane vesicles was estimated to be pH 6.3, which would indicate that at physiological apoplastic pH Suc transport might be sensitive to changes in pHo. On the other hand, the [H+]i for half-maximal inhibition of Suc uptake was approximately pH 5.4, making regulation of Suc transport through changes in [H+]i unlikely. These results were interpreted in the framework of the kinetics models for co-transport systems developed by D. Sanders, U.-P. Hansen, D. Gradmann, and C. L. Slayman (J Membr Biol [1984] 77: 123-152). Based on their analysis, the behavior of the Suc symporter with respect to the [H+]i is interpreted as an ordered binding mechanism by which the binding of Suc on the apoplastic side of the membrane and its release on the symplastic side precedes that of H+ (i.e. a first-on, first-off model).

Buckhout, T. J.

1994-01-01

99

The role of transport processes in survival of lactic acid bacteria, Energy transduction and multidrug resistance  

Microsoft Academic Search

Lactic acid bacteria play an essential role in many food fermentation processes. They are anaerobic organisms which obtain their metabolic energy by substrate phosphorylation. In addition three secondary energy transducing processes can contribute to the generation of a proton motive force: proton\\/substrate symport as in lactic acid excretion, electrogenic precursor\\/product exchange as in malolactic and citrolactic fermentation and histidine\\/histamine exchange,

W. N. Konings; J. S. Lolkema; H. Bolhuis; H. W. van Veen; B. Poolman; A. J. M. Driessen

1997-01-01

100

Probasin Promoter (ARR2PB)Driven, Prostate-Specific Expression of the Human Sodium Iodide Symporter (h-NIS) for Targeted Radioiodine Therapy of Prostate Cancer  

Microsoft Academic Search

Prostate cancer is one of the most promising candidates for sodium iodide symporter (NIS)-mediated gene therapy. Adenovirus-mediated ex- pression of NIS that is driven by prostate-specific promoters induces generous radioiodine accumulation in prostate cancer cells that may be used for therapy with 131I. We have recently developed a replication- deficient adenovirus carrying the human NIS cDNA linked to a composite

Hideaki Kakinuma; Elizabeth R. Bergert; Christine Spitzweg; John C. Cheville; Michael M. Lieber; John C. Morris

2003-01-01

101

HSV-NIS, an oncolytic herpes simplex virus type 1 encoding human sodium iodide symporter for preclinical prostate cancer radiovirotherapy  

PubMed Central

Several clinical trials have shown that oncolytic herpes simplex virus type 1 (oHSV-1) can be safely administered to patients. However, virus replication in tumor tissue has generally not been monitored in these oHSV clinical trials, and the data suggest that its oncolytic potency needs to be improved. To facilitate noninvasive monitoring of the in vivo spread of an oHSV and to increase its antitumor efficacy, the gene coding for human sodium iodide symporter (NIS) was incorporated into a recombinant oHSV genome and the corresponding virus (oHSV-NIS) rescued in our laboratory. Our data demonstrate that a human prostate cancer cell line, LNCap, efficiently concentrates radioactive iodine after the cells have been infected in vitro or in vivo. In vivo replication of oHSV-NIS in tumors was noninvasively monitored by computed tomography/single-photon emission computed tomography imaging of the biodistribution of pertechnetate and was confirmed. LNCap xenografts in nude mice were eradicated by intratumoral administration of oHSV-NIS. Systemic administration of oHSV-NIS prolonged the survival of tumor-bearing mice, and the therapeutic effect was further enhanced by administration of 131I after the intratumoral spread of the virus had peaked. oHSV-NIS has the potential to substantially enhance the outcomes of standard therapy for patients with prostate cancer.

Li, H; Nakashima, H; Decklever, T D; Nace, R A; Russell, S J

2013-01-01

102

Therapeutic Effect of Sodium Iodide Symporter Gene Therapy Combined With External Beam Radiotherapy and Targeted Drugs That Inhibit DNA Repair  

PubMed Central

Adenoviral (AdV) transfer of sodium iodide symporter (NIS) gene has translational potential, but relatively low levels of transduction and subsequent radioisotope uptake limit the efficacy of the approach. In previous studies, we showed that combining NIS gene delivery with external beam radiotherapy (EBRT) and DNA damage repair inhibitors increased viral gene expression and radioiodide uptake. Here, we report the therapeutic efficacy of this strategy. An adenovirus expressing NIS from a telomerase promoter (Ad-hTR-NIS) was cytotoxic combined with relatively high-dose (50 µCi) 131I therapy and enhanced the efficacy of EBRT combined with low-dose (10 and 25 µCi) 131I therapy in colorectal and head and neck cancer cells. Combining this approach with ataxia-telangiectasia mutated (ATM) or DNA-dependent protein kinase (DNA-PK) inhibition caused maintenance of double-stranded DNA breaks (DSBs) at 24 hours and increased cytotoxicity on clonogenic assay. When the triplet of NIS-mediated 131I therapy, EBRT, and DNA-PKi was used in vivo, 90% of mice were tumor-free at 5 weeks. Acute radiation toxicity in the EBRT field was not exacerbated. In contrast, DNA-PKi did not enhance the therapeutic efficacy of EBRT plus adenovirus-mediated HSVtk/ganciclovir (GCV). Therefore, combining NIS gene therapy and EBRT represents an ideal strategy to exploit the therapeutic benefits of novel radiosensitizers.

Hingorani, Mohan; White, Christine L; Zaidi, Shane; Pandha, Hardev S; Melcher, Alan A; Bhide, Shreerang A; Nutting, Christopher M; Syrigos, Konstantinos N; Vile, Richard G; Vassaux, Georges; Harrington, Kevin J

2010-01-01

103

Targeting of tumor radioiodine therapy by expression of the sodium iodide symporter under control of the survivin promoter  

PubMed Central

To test the feasibility of using the survivin promoter to induce specific expression of sodium/iodide symporter (NIS) in cancer cell lines and tumors for targeted use of radionuclide therapy, a recombinant adenovirus, Ad-SUR-NIS, that expressed the NIS gene under control of the survivin promoter was constructed. Ad-SUR-NIS mediating iodide uptake and cytotoxicity was performed in vitro. Scintigraphic, biodistribution and radioiodine therapy studies were performed in vivo. PC-3 (prostate); HepG2 (hepatoma) and A375 (melanoma) cancer cells all exhibited perchlorate-sensitive iodide uptake after infection with Ad-SUR-NIS, ?50 times higher than that of negative control Ad-CMV-GFP-infected cells. No significant iodide uptake was observed in normal human dental pulp fibroblast (DPF) cells after infection with Ad-SUR-NIS. Clonogenic assays demonstrated that Ad-SUR-NIS-infected cancer cells were selectively killed by exposure to 131I. Ad-SUR-NIS-infected tumors show significant radioiodine accumulation (13.3±2.85% ID per g at 2?h post-injection), and the effective half-life was 3.1?h. Moreover, infection with Ad-SUR-NIS in combination with 131I suppressed tumor growth. These results indicate that expression of NIS under control of the survivin promoter can likely be used to achieve cancer-specific expression of NIS in many types of cancers. In combination with radioiodine therapy, this strategy is a possible method of cancer gene therapy.

Huang, R; Zhao, Z; Ma, X; Li, S; Gong, R; Kuang, A

2011-01-01

104

Role of Gly117 in the cation/melibiose symport of MelB of Salmonella typhimurium  

PubMed Central

The melibiose permease of Salmonella typhimurium (MelBSt) catalyzes symport of melibiose with Na+, Li+ or H+, and bioinformatics analysis indicates that a conserved Gly117 (helix IV) is part of the Na+-binding site. We mutated Gly117 to Ala, Pro, Trp or Arg; the effects on melibiose transport and binding of cosubstrates depended on the physical-chemical properties of the side chain. Compared with WT MelBSt, the Gly117?Ala mutant exhibited little difference in either cosubstrate binding or stimulation of melibiose transport by Na+ or Li+, but all other mutations reduced melibiose active transport and efflux, and decreased the apparent affinity for Na+. The bulky Trp at position 117 caused the greatest inhibition of melibiose binding, and Gly117?Arg yielded less than a 4-fold decrease in the apparent affinity for melibiose at saturating Na+ or Li+ concentration. Remarkably, the mutant Gly117?Arg catalyzed melibiose exchange in the presence of Na+ or Li+, but did not catalyze melibiose translocation involving net flux of the coupling cation, indicating that sugar is released prior to release of the coupling cation. Taken together, the findings are consistent with the notion that Gly117 plays an important role in cation binding and translocation.

Guan, Lan; Jakkula, S. Vivek; Hodkoff, Alexey A.; Su, Yue

2012-01-01

105

HSV-NIS, an oncolytic herpes simplex virus type 1 encoding human sodium iodide symporter for preclinical prostate cancer radiovirotherapy.  

PubMed

Several clinical trials have shown that oncolytic herpes simplex virus type 1 (oHSV-1) can be safely administered to patients. However, virus replication in tumor tissue has generally not been monitored in these oHSV clinical trials, and the data suggest that its oncolytic potency needs to be improved. To facilitate noninvasive monitoring of the in vivo spread of an oHSV and to increase its antitumor efficacy, the gene coding for human sodium iodide symporter (NIS) was incorporated into a recombinant oHSV genome and the corresponding virus (oHSV-NIS) rescued in our laboratory. Our data demonstrate that a human prostate cancer cell line, LNCap, efficiently concentrates radioactive iodine after the cells have been infected in vitro or in vivo. In vivo replication of oHSV-NIS in tumors was noninvasively monitored by computed tomography/single-photon emission computed tomography imaging of the biodistribution of pertechnetate and was confirmed. LNCap xenografts in nude mice were eradicated by intratumoral administration of oHSV-NIS. Systemic administration of oHSV-NIS prolonged the survival of tumor-bearing mice, and the therapeutic effect was further enhanced by administration of (131)I after the intratumoral spread of the virus had peaked. oHSV-NIS has the potential to substantially enhance the outcomes of standard therapy for patients with prostate cancer. PMID:23868101

Li, H; Nakashima, H; Decklever, T D; Nace, R A; Russell, S J

2013-07-19

106

A Steep Radioiodine Dose Response Scalable to Humans in Sodium Iodide Symporter (NIS) Mediated Radiovirotherapy for Prostate Cancer  

PubMed Central

The sodium iodide symporter (NIS) directs the uptake and concentration of iodide in thyroid cells. We have extended the use of NIS-mediated radioiodine therapy to prostate cancer. We have developed a prostate tumor specific conditionally replicating adenovirus (CRAd) that expresses hNIS (Ad5PB_RSV-NIS). For radiovirotherapy to be effective in humans, the radioiodine dose administered in the pre-clinical animal model should scale to the range of acceptable doses in humans. We performed 131I dose-response experiments aiming to determine the dose required in mice to achieve efficient radiovirotherapy. Efficacy was determined by measuring tumor growth and survival times. We observed that individual tumors display disparate growth rates which preclude averaging within a treatment modality indicating heterogeneity of growth rate. We further show that a statistic and stochastic approach must be used when comparing the effect of an anti-cancer therapy on a cohort of tumors. Radiovirotherapy improves therapeutic value over virotherapy alone by slowing the rate of tumor growth in a more substantial manner leading to an increase in survival time. We also show that the radioiodine doses needed to achieve this increase scaled well within the current doses used for treatment of thyroid cancer in humans.

Trujillo, Miguel A.; Oneal, Michael J.; McDonough, Samantha; Qin, Rui; Morris, John C.

2012-01-01

107

Sequence of a Na +\\/glucose symporter gene and its flanking regions of Vibrio parahaemolyticus  

Microsoft Academic Search

The nucleotide sequence of an approximately 6 kbp segment of chromosomal DNA of Vibrio parahaemolyticus was determined. The nucleotide sequence revealed four open reading frames (ORFs) in this region. Hydropathy profiles of the deduced amino acid sequence of the ORFs indicate that ORF1 encodes a hydrophobic polypeptide with typical characteristics of a membrane transport protein. All other ORFs encode hydrophilic

Rafiquel I. Sarker; Yoshie Okabe; Masaaki Tsuda; Tomofusa Tsuchiya

1996-01-01

108

NMR observation of substrate in the binding site of an active sugar-H+ symport protein in native membranes.  

PubMed Central

NMR methods have been adopted to observe directly the characteristics of substrate binding to the galactose-H+ symport protein GalP, in its native environment, the inner membranes of Escherichia coli. Sedimented inner-membrane vesicles containing the GalP protein, overexpressed to levels above 50% of total protein, were analyzed by 13C magic-angle spinning NMR, when in their normal "fluid" state and with incorporated D-[1-13C]glucose. Using conditions of cross-polarization intended to discriminate bound substrate alone, it was possible to detect as little as 250 nmol of substrate added to the membranes containing about 0.5 mumol (approximately 26 mg) of GalP protein. Such high measuring sensitivity was possible from the fluid membranes by virtue of their motional contributions to rapid relaxation recovery of the observed nuclei and due to a high-resolution response that approached the static field inhomogeneity in these experiments. This good spectral resolution showed that the native state of the membranes presents a substrate binding environment with high structural homogeneity. Inhibitors of the GalP protein, cytochalasin B and forskolin, which are specific, and D-galactose, but not L-galactose, prevent or suppress detection of the 13C-labeled glucose substrate, confirming that the observed signal was due to specific interactions with the GalP protein. This specific substrate binding exhibits a preference for the beta-anomer of D-glucose and substrate translocation is determined to be slow, on the 10(-2) s time scale. The work describes a straightforward NMR approach, which achieves high sensitivity, selectivity, and resolution for nuclei associated with complex membrane proteins and which may be combined with other NMR methodologies to yield additional structural information on the binding site for the current transport system without isolating it from its native membrane environment. Images

Spooner, P J; Rutherford, N G; Watts, A; Henderson, P J

1994-01-01

109

Differential expression of the Na+/I? symporter protein in thyroid cancer and adjacent normal and nodular goiter tissues  

PubMed Central

The ability of differentiated thyroid cancer and adjacent thyroid cells to concentrate iodine is dependent on their expression of a functional NA+/I? symporter (NIS). Thyroid cancer is insensitive to 131I treatment if the thyroid cells lack the ability to concentrate iodide. Thus, in this study, we aimed to determine whether the NIS protein was differentially expressed in thyroid cancer and various surrounding tissues. We recruited 114 cases of papillary thyroid carcinoma (PTC) and divided them into two groups: 60 patients of 9 males and 51 females with a mean age of 49.55 years who had PTC with surrounding nodular goiter tissue (simplified as GNG), and 54 patients of 8 males and 46 females with a mean age of 45.78 years who had PTC with surrounding normal tissue (Gnormal) after total or near total thyroidectomy. Formalin-fixed and paraffin-embedded tissue sections were prepared for immunohistochemical staining of the NIS protein and semi-quantitative analysis. The NIS protein was expressed in the basolateral membrane of the normal epithelium, while PTC and nodular goiter cells expressed NIS in the cytoplasm and basolateral membrane. The expression levels of the NIS protein were higher in the adjacent normal tissues compared with those of the surrounding nodular goiter tissues (P=0.002) and expression levels of the NIS protein were higher in PTC tissues compared with the surrounding nodular goiter tissues (P=0.008). The data from this study indicate that cancer-surrounding tissues may play a significant role in mediating the sensitivity of PTC patients to radioactive iodine treatment.

WANG, SHASHA; LIANG, JUN; LIN, YANSONG; YAO, RUYONG

2013-01-01

110

Phosphoinositide-3-kinase inhibition induces sodium/iodide symporter expression in rat thyroid cells and human papillary thyroid cancer cells.  

PubMed

TSH stimulation of sodium iodide symporter (NIS) expression in thyroid cancer promotes radioiodine uptake and is required to deliver an effective treatment dose. Activation of the insulin/phosphoinositide-3-kinase (PI3K) signaling pathway in TSH-stimulated thyroid cells reduces NIS expression at the transcriptional level. We, therefore, investigated the effects of PI3K pathway inhibition on iodide uptake and NIS expression in rat thyroid cell lines and human papillary thyroid cancer cells. A PI3K inhibitor, LY294002, significantly enhanced iodide uptake in two rat thyroid cell lines, FRTL-5 and PCCL3. The induction of Nis mRNA by LY294002 occurred 6 h after treatment, and was abolished by a translation inhibitor, cycloheximide. Expression of the transcription factor, Pax8, which stimulates NIS expression, was significantly increased in PCCL3 cells after LY294002 treatment. Removal of insulin abrogated the stimulatory effects of LY294002 on NIS mRNA and protein expression, but not on iodide uptake. These findings suggest that PI3K pathway inhibition results in post-translational stimulation of NIS. Inhibition of the PI3K pathway also significantly increased iodide uptake ( approximately 3.5-fold) in BHP 2-7 papillary thyroid cancer cells (Ret/PTC1 positive), engineered to constitutively express NIS. Pharmacological inhibition of Akt, a factor stimulated by the PI3K pathway, increased exogenous NIS expression in BHP 2-7 as was seen with LY294002, but not increase the endogenous NIS expression in FRTL-5 cells. PI3K pathway inhibition increases functional NIS expression in rat thyroid cells and some papillary thyroid cancer cells by several mechanisms. PI3K inhibitors have the potential to increase radioiodide accumulation in some differentiated thyroid cancer. PMID:18762555

Kogai, Takahiko; Sajid-Crockett, Saima; Newmarch, Lynell S; Liu, Yan-Yun; Brent, Gregory A

2008-09-01

111

Dexamethasone enhances the cytotoxic effect of radioiodine therapy in prostate cancer cells expressing the sodium iodide symporter.  

PubMed

Recently, we have reported the induction of prostate-specific radioiodine accumulation in prostate cancer cells (LNCaP) using a prostate-specific antigen (PSA)-promoter-directed expression of the sodium iodide symporter (NIS) gene. This offers the potential to treat prostate cancer with radioiodine. The aim of our current study was to examine the regulation of PSA-promoter-directed NIS expression in NIS-transfected LNCaP cells (NP-1) by dexamethasone (Dex). For this purpose, NIS mRNA and protein expression levels were examined in NP-1 cells by Northern and Western blot analysis, respectively, after incubation with Dex (10(-8)-10(-6) M) in the presence of 10(-9) M mibolerone. NIS functional activity was measured by iodide uptake assay. In addition, we examined regulation of in vitro cytotoxicity of 131-I by Dex in an in vitro clonogenic assay. After incubation with Dex, iodide accumulation in NP-1 cells increased up to 1.5-fold, whereas NIS mRNA and protein expression levels were increased up to 1.7-fold. This effect of Dex was blocked by the androgen receptor antagonist casodex (10(-6) M). The killing effect of 131-I in NP-1 cells was increased from 55% when incubated with mibolerone alone to 95% when treated with Dex (10(-7) M) plus mibolerone. Treatment of NP-1 cells with Dex resulted in an additional antiproliferative effect as measured by clonogenic assay and nonradioactive proliferation assay. In conclusion, in addition to an antiproliferative effect, treatment with Dex increases androgen-dependent NIS mRNA and protein expression as well as iodide accumulation, resulting in an increased cytotoxic effect of 131-I in prostate cancer cells stably expressing NIS under the control of the PSA-promoter. PMID:15001595

Scholz, I V; Cengic, N; Göke, B; Morris, J C; Spitzweg, C

2004-03-01

112

Treatment of prostate cancer by radioiodine therapy after tissue-specific expression of the sodium iodide symporter.  

PubMed

Causing prostate cancer cells to express functionally active sodium iodide symporter (NIS) by targeted NIS gene transfer might offer the possibility of radioiodine therapy of prostate cancer. Therefore, we investigated radioiodine accumulation and therapeutic effectiveness of 131I in NIS-transfected prostate cancer cells in vitro and in vivo. The human prostatic adenocarcinoma cell line LNCaP was stably transfected with NIS cDNA under the control of the prostate-specific antigen promoter. The stably transfected LNCaP cell line NP-1 showed perchlorate-sensitive, androgen-dependent iodide uptake in vitro that resulted in selective killing of these cells by 131I in an in vitro clonogenic assay. Xenografts were established in athymic nude mice and imaged using a gamma camera after i.p. injection of 500 microCi of 123I. In contrast to the NIS-negative control tumors (P-1) which showed no in vivo uptake of 123I, NP-1 tumors accumulated 25-30% of the total 123I administered with a biological half-life of 45 h. In addition, NIS protein expression in LNCaP cell xenografts was confirmed by Western blot analysis and immunohistochemistry. After a single i.p. application of a therapeutic 131I dose (3 mCi), significant tumor reduction was achieved in NP-1 tumors in the therapy group compared with P-1 tumors and tumors in the control group. In conclusion, a therapeutic effect of 131I has been demonstrated in prostate cancer cells after induction of tissue-specific iodide uptake activity by prostate-specific antigen promoter-directed NIS expression in vitro and in vivo. This study demonstrates the potential of NIS as a novel therapeutic gene for nonthyroidal cancers, in particular prostate cancer. PMID:11103823

Spitzweg, C; O'Connor, M K; Bergert, E R; Tindall, D J; Young, C Y; Morris, J C

2000-11-15

113

Radioiodide treatment after sodium iodide symporter gene transfer is a highly effective therapy in neuroendocrine tumor cells.  

PubMed

This study evaluates the possibility of treating Bon1 and QGP pancreatic neuroendocrine tumor cells with radioactive iodide ((131)I) after stable transfection with the thyroid sodium iodide symporter (NIS). NIS expression was driven either by the strong viral cytomegalovirus promoter or by the tissue-specific chromogranin A promoter. Using either approach, NIS expression was confirmed by reverse transcription-PCR and Western blotting. Uptake of radioactive iodide was increased approximately 20-fold by chromogranin A promoter-driven NIS expression and approximately 50-fold by cytomegalovirus promoter-driven NIS expression. Maximal uptake was reached within 15 min in QGP cells and 30 min in Bon1 cells. Effective half-life was 5 min in QGP and 30 min in Bon1 cells. No evidence of organification was detected by high-performance liquid chromatography and gel filtration chromatography. (131)I was a highly effective treatment in NIS-expressing QGP and Bon1 cells, reducing clone formation by 99.83 and 98.75%, respectively, in the in vitro clonogenic assay. In contrast, clone formation was not reduced in QGP and Bon1 cells without NIS expression after incubation with the same activity concentration of (131)I as compared with mock treated cells. Absorbed doses to QGP and Bon1 cells are up to 150 and 30 Gy, respectively. In addition, a direct cytotoxic effect of radioiodide was demonstrated in NIS-expressing Bon1 cells after (131)I incubation. In conclusion, radioiodide treatment after NIS gene transfer appears to be a promising novel approach in the therapy of neuroendocrine tumors if its highly encouraging in vitro effectiveness can be transferred to the in vivo situation. PMID:12649195

Schipper, Meike L; Weber, Alexander; Béhé, Martin; Göke, Rüdiger; Joba, Werner; Schmidt, Harald; Bert, Till; Simon, Babette; Arnold, Rudolf; Heufelder, Armin E; Behr, Thomas M

2003-03-15

114

Dietary iodide controls its own absorption through post-transcriptional regulation of the intestinal Na+/I- symporter.  

PubMed

Dietary I(-) absorption in the gastrointestinal tract is the first step in I(-) metabolism. Given that I(-) is an essential constituent of the thyroid hormones, its concentrating mechanism is of significant physiological importance. We recently described the expression of the Na(+)/I(-) symporter (NIS) on the apical surface of the intestinal epithelium as a central component of the I(-) absorption system and reported reduced intestinal NIS expression in response to an I(-)-rich diet in vivo. Here, we evaluated the mechanism involved in the regulation of NIS expression by I(-) itself in enterocytes. Excess I(-) reduced NIS-mediated I(-) uptake in IEC-6 cells in a dose- and time-dependent fashion, which was correlated with a reduction of NIS expression at the plasma membrane. Perchlorate, a competitive inhibitor of NIS, prevented these effects, indicating that an increase in intracellular I(-) regulates NIS. Iodide induced rapid intracellular recruitment of plasma membrane NIS molecules and NIS protein degradation. Lower NIS mRNA levels were detected in response to I(-) treatment, although no transcriptional effect was observed. Interestingly, I(-) decreased NIS mRNA stability, affecting NIS translation. Heterologous green fluorescent protein-based reporter constructs revealed a significant repressive effect of the I(-)-targeting NIS mRNA 3 untranslated region. In conclusion, excess I(-) downregulates NIS expression in enterocytes by virtue of a complex mechanism. Our data suggest that I(-) regulates intestinal NIS mRNA expression at the post-transcriptional level as part of an autoregulatory effect of I(-) on its own metabolism. PMID:23006481

Nicola, Juan Pablo; Reyna-Neyra, Andrea; Carrasco, Nancy; Masini-Repiso, Ana Maria

2012-09-24

115

The sodium/iodide symporter NIS is a transcriptional target of the p53-family members in liver cancer cells  

PubMed Central

Thyroid iodide accumulation via the sodium/iodide symporter (NIS; SLC5A5) has been the basis for the longtime use of radio-iodide in the diagnosis and treatment of thyroid cancers. NIS is also expressed, but poorly functional, in some non-thyroid human cancers. In particular, it is much more strongly expressed in cholangiocarcinoma (CCA) and hepatocellular carcinoma (HCC) cell lines than in primary human hepatocytes (PHH). The transcription factors and signaling pathways that control NIS overexpression in these cancers is largely unknown. We identified two putative regulatory clusters of p53-responsive elements (p53REs) in the NIS core promoter, and investigated the regulation of NIS transcription by p53-family members in liver cancer cells. NIS promoter activity and endogenous NIS mRNA expression are stimulated by exogenously expressed p53-family members and significantly reduced by member-specific siRNAs. Chromatin immunoprecipitation analysis shows that the p53–REs clusters in the NIS promoter are differentially occupied by the p53-family members to regulate basal and DNA damage-induced NIS transcription. Doxorubicin strongly induces p53 and p73 binding to the NIS promoter, leading to an increased expression of endogenous NIS mRNA and protein in HCC and CCA cells, but not in PHH. Silencing NIS expression reduced doxorubicin-induced apoptosis in HCC cells, pointing to a possible role of a p53-family-dependent expression of NIS in apoptotic cell death. Altogether, these results indicate that the NIS gene is a direct target of the p53 family and suggests that the modulation of NIS by DNA-damaging agents is potentially exploitable to boost NIS upregulation in vivo.

Guerrieri, F; Piconese, S; Lacoste, C; Schinzari, V; Testoni, B; Valogne, Y; Gerbal-Chaloin, S; Samuel, D; Brechot, C; Faivre, J; Levrero, M

2013-01-01

116

Induction of Sodium/Iodide Symporter (NIS) Expression and Radioiodine Uptake in Non-Thyroid Cancer Cells  

PubMed Central

Background This study was designed to explore the therapeutic potential of suppressing MAP kinase and PI3K/Akt pathways and histone deacetylase (HDAC) to induce the expression of sodium/iodide symporter (NIS) and radioiodine uptake in non-thyroid cancer cells. Methods We tested the effects of the MEK inhibitor RDEA119, the Akt inhibitor perifosine, and the HDAC inhibitor SAHA on NIS expression in thirteen human cancer cell lines derived from melanoma, hepatic carcinoma, gastric carcinoma, colon carcinoma, breast carcinoma, and brain cancers. We also examined radioiodine uptake and histone acetylation at the NIS promoter in selected cells. Results Overall, the three inhibitors could induce NIS expression, to various extents, in melanoma and all the epithelial carcinoma-derived cells but not in brain cancer-derived cells. SAHA was most effective and its effect could be significantly enhanced by RDEA119 and perifosine. The expression of NIS, at both mRNA and protein levels, was most robust in the melanoma cell M14, hepatic carcinoma cell HepG2, and the gastric carcinoma cell MKN-7 cell. Radioiodine uptake was correspondingly induced, accompanied by robust increase in histone acetylation at the NIS promoter, in these cells when treated with the three inhibitors. Conclusions This is the first demonstration that simultaneously suppressing the MAP kinase and PI3K/Akt pathways and HDAC could induce robust NIS expression and radioiodine uptake in certain non-thyroid human cancer cells, providing novel therapeutic implications for adjunct radioiodine treatment of these cancers.

Liu, Zhi; Xing, Mingzhao

2012-01-01

117

Posttranscriptional regulation of sodium-iodide symporter mRNA expression in the rat thyroid gland by acute iodide administration.  

PubMed

Iodide is an important regulator of thyroid activity. Its excess elicits the Wolff-Chaikoff effect, characterized by an acute suppression of thyroid hormone synthesis, which has been ascribed to serum TSH reduction or TGF-beta increase and production of iodolipids in the thyroid. These alterations take hours/days to occur, contrasting with the promptness of Wolff-Chaikoff effect. We investigated whether acute iodide administration could trigger events that precede those changes, such as reduction of sodium-iodide symporter (NIS) mRNA abundance and adenylation, and if perchlorate treatment could counteract them. Rats subjected or not to methylmercaptoimidazole treatment (0.03%) received NaI (2,000 microg/0.5 ml saline) or saline intraperitoneally and were killed 30 min up to 24 h later. Another set of animals was treated with iodide and perchlorate, in equimolar doses. NIS mRNA content was evaluated by Northern blotting and real-time PCR, and NIS mRNA poly(A) tail length by rapid amplification of cDNA ends-poly(A) test (RACE-PAT). We observed that NIS mRNA abundance and poly(A) tail length were significantly reduced in all periods of iodide treatment. Perchlorate reversed these effects, indicating that iodide was the agent that triggered the modifications observed. Since the poly(A) tail length of mRNAs is directly associated with their stability and translation efficiency, we can assume that the rapid decay of NIS mRNA abundance observed was due to a reduction of its stability, a condition in which its translation could be impaired. Our data show for the first time that iodide regulates NIS mRNA expression at posttranscriptional level, providing a new mechanism by which iodide exerts its autoregulatory effect on thyroid. PMID:20107044

Serrano-Nascimento, Caroline; Calil-Silveira, Jamile; Nunes, Maria Tereza

2010-01-27

118

Locating an extracellular K+-dependent interaction site that modulates betaine-binding of the Na+-coupled betaine symporter BetP.  

PubMed

BetP, a trimeric Na(+)-coupled betaine symporter, senses hyperosmotic stress via its cytoplasmic C-terminal domain and regulates transport activity in dependence of the cytoplasmic K(+)-concentration. This transport regulation of BetP depends on a sophisticated interaction network. Using single-molecule force spectroscopy we structurally localize and quantify these interactions changing on K(+)-dependent transport activation and substrate-binding. K(+) significantly strengthened all interactions, modulated lifetimes of functionally important structural regions, and increased the mechanical rigidity of the symporter. Substrate-binding could modulate, but not establish most of these K(+)-dependent interactions. A pronounced effect triggered by K(+) was observed at the periplasmic helical loop EH2. Tryptophan quenching experiments revealed that elevated K(+)-concentrations akin to those BetP encounters during hyperosmotic stress trigger the formation of a periplasmic second betaine-binding (S2) site, which was found to be at a similar position reported previously for the BetP homologue CaiT. In BetP, the presence of the S2 site strengthened the interaction between EH2, transmembrane ?-helix 12 and the K(+)-sensing C-terminal domain resulting in a K(+)-dependent cooperative betaine-binding. PMID:21987793

Ge, Lin; Perez, Camilo; Waclawska, Izabela; Ziegler, Christine; Muller, Daniel J

2011-10-10

119

Role of a sodium-dependent symporter homologue in the thermosensitivity of beta-lactam antibiotic resistance and cell wall composition in Staphylococcus aureus.  

PubMed

Expression of high-level beta-lactam resistance is known to be thermosensitive in many methicillin-resistant Staphylococcus aureus (MRSA) strains, including strain COL, in which the high methicillin MIC for cultures grown at 37 degrees C (800 microg/ml) was reduced to 12 microg/ml at 42 degrees C. COL grew faster at 42 degrees C than at 37 degrees C and at the higher temperature produced cell walls of abnormal composition: there was an over-representation of the monomeric muropeptide without the oligoglycine chain and an increase in the representation of multimers that contained this wall component as the donor molecule. Screening of a Tn551 insertional library for mutants, in which the high and homogenous beta-lactam antibiotic resistance of strain COL is retained at 42 degrees C, identified mutant C245, which expressed high-level methicillin resistance and produced a cell wall of normal composition independent of the temperature. The Tn551 inactivated gene was found, by homology search, to encode for a sodium-dependent symporter, homologues of which are ubiquitous in both prokaryotic and eukaryotic genomes. Inactivation of this putative symporter in several heteroresistant clinical MRSA isolates caused striking increases in the level of their beta-lactam resistance. PMID:18056270

Sieradzki, Krzysztof; Chung, Marilyn; Tomasz, Alexander

2007-12-03

120

A novel eukaryotic Na+ methionine selective symporter is essential for mosquito development.  

PubMed

AeNAT5 (NCBI, ABZ81822), an orphan member of the insect-specific Nutrient Amino acid Transporter subfamily of SoLute Carrier family 6 (NAT-SLC6) and the first representative of a novel eukaryotic methionine-selective transport system (M), was cloned from cDNA of the vector mosquito, Aedes aegypti. It has orphan orthologs throughout several mosquito genomes, but not in Drosophila or outside Diptera. It shows the highest apparent affinity to L-Met (K(0.5) = 0.021 mM) and its metabolites Homocysteine and Cysteine (K(0.5) = 0.89 and 2.16 mM), but weakly interact with other substrates. It has a Na(+) - coupled mechanism (K(0.5) Na(+) ? 46 mM) with 1AA:1Na(+) stoichiometry that maintains ?60% activity in Cl(-) - free media. In situ hybridization showed accumof AeNAT5 transcript in the absorptive and secretory epithelia, as well as in specific peripheral neurons and the central ganglia of mosquito larvae. The labeling pattern is distinct from that of the previously characterized AeNAT1. RNAi of AeNAT5 increases larval mortality during ecdysis and dramatically suppresses adult emergence. Our results showed that in addition to previously characterized broad spectra and aromatic amino acid selective transport systems, the mosquito NAT-SLC6 subfamily evolved a unique mechanism for selective absorption of sulfur-containing substrates. We demonstrated specific patterns of alimentary and neuronal transcription of AeNAT5 in mosquito larvae that is collateral with the indispensable function of this transporter in mosquito development. PMID:23748165

Meleshkevitch, Ella A; Voronov, Dmitri A; Miller, Melissa M; Penneda, Maria; Fox, Jeffrey M; Metzler, Ryan; Boudko, Dmitri Y

2013-06-06

121

Effect of thyroid statuses on sodium/iodide symporter (NIS) gene expression in the extrathyroidal tissues in mice  

PubMed Central

Background Iodide that is essential for thyroid hormone synthesis is actively transported into the thyroid follicular cells via sodium/iodide symporter (NIS) protein in vertebrates. It is well known that NIS expression in thyroid is regulated by the thyroid statuses mainly through thyroid stimulating hormone (TSH). Although NIS mRNA expressions in extrathyroidal tissues have been qualitatively reported, their regulation by thyroid statuses has not been well clarified. Methods Male ICR mice aged four weeks were assigned into three groups (control, hypothyroid, and hyperthyroid). Hypothyroid group of mice were treated with 0.02% methimazole in drinking water and hyperthyroid group of mice received intraperitoneal injection (4 ?g L-T4 twice a week) for four weeks. NIS mRNA expression levels in the tissues were evaluated using Northern blot hybridization and quantitative real-time RTPCR (qPCR). Additionally, end-point RTPCR for the thyroid follicular cell-characteristic genes (TSH receptor, TSHR; thyroid transcription factor-1, TTF1; and paired box gene 8, Pax8) was carried out. Results By Northern blot analysis, NIS mRNA was detected in thyroid and stomach. In addition to these organs, qPCR revealed the expression also in the submandibular gland, colon, testis, and lung. Expression of NIS mRNA in thyroid was significantly increased in hypothyroid and decreased in hyperthyroid group. Trends of NIS mRNA expression in extrathyroidal tissues were not in line with that in the thyroid gland in different thyroid statuses. Only in lung, NIS mRNA was regulated by thyroid statuses but in opposite way compared to the manner in the thyroid gland. There were no extrathyroidal tissues that expressed all three characteristic genes of thyroid follicular cells. Conclusions NIS mRNA expression in the thyroid gland was up-regulated in hypothyroid mice and was down-regulated in hyperthyroid mice, suggesting that NIS mRNA in the thyroid gland is regulated by thyroid statuses. In contrast, NIS mRNA expression in extrathyroidal tissues was not altered by thyroid statuses although it was widely expressed. Lack of responsiveness of NIS mRNA expressions in extrathyroidal tissues reemphasizes additional functions of NIS protein in extrathyroidal tissues other than iodide trapping.

2010-01-01

122

Construction of an MUC-1 promoter driven, conditionally replicating adenovirus that expresses the sodium iodide symporter for gene therapy of breast cancer  

PubMed Central

Introduction The sodium iodide symporter (NIS) directs the uptake and concentration of iodide in thyroid cells. This in turn allows radioiodine imaging and therapy for thyroid cancer. To extend the use of NIS-mediated radioiodine therapy to other types of cancer, we successfully transferred and expressed the sodium-iodide symporter (NIS) gene in prostate, colon, and breast cancer cells both in vivo and in vitro by using non-replicating adenoviral vectors. Methods To improve virotherapy efficiency, we developed a conditionally replicating adenovirus (CRAd) in which the transcriptional cassette RSV promoter-human NIScDNA-bGH polyA was also inserted at the E3 region. The E1a gene is driven by the tumor-specific promoter MUC-1 in the CRAd Ad5AMUCH_RSV-NIS. Results In vitro infection of the MUC-1-positive breast cell line T47D resulted in virus replication, cytolysis, and release of infective viral particles. Conversely, the MUC-1-negative breast cancer cell line MDA-MB-231 was refractory to the viral cytopathic effect and did not support viral replication. The data indicate that Ad5AMUCH_RSV-NIS activity is stringently restricted to MUC-1-positive cancer cells. Radioiodine uptake was readily measurable in T47 cells infected with Ad5AMUCH_RSV-NIS 24 hours after infection, thus confirming NIS expression before viral-induced cell death. Conclusions This construct may allow multimodal therapy, combining virotherapy with radioiodine therapy to be developed as a novel treatment for breast and other MUC1-overexpressing cancers.

Trujillo, Miguel A; Oneal, Michael J; Davydova, Julia; Bergert, Elizabeth; Yamamoto, Masato; Morris, John C

2009-01-01

123

Arabidopsis thaliana POLYOL/MONOSACCHARIDE TRANSPORTERS 1 and 2: fructose and xylitol/H+ symporters in pollen and young xylem cells  

PubMed Central

The genome of Arabidopsis thaliana contains six genes, AtPMT1 to AtPMT6 (Arabidopsis thaliana POLYOL/MONOSACCHARIDE TRANSPORTER 1–6), which form a distinct subfamily within the large family of more than 50 monosaccharide transporter-like (MST-like) genes. So far, only AtPMT5 [formerly named AtPLT5 (At3g18830)] has been characterized and was shown to be a plasma membrane-localized H+-symporter with broad substrate specificity. The characterization of AtPMT1 (At2g16120) and AtPMT2 (At2g16130), two other, almost identical, members of this transporter subfamily, are presented here. Expression of the AtPMT1 and AtPMT2 cDNAs in baker's yeast (Saccharomyces cerevisiae) revealed that these proteins catalyse the energy-dependent, high-capacity transport of fructose and xylitol, and the transport of several other compounds with lower rates. Expression of their cRNAs in Xenopus laevis oocytes showed that both proteins are voltage-dependent and catalyse the symport of their substrates with protons. Fusions of AtPMT1 or AtPMT2 with the green fluorescent protein (GFP) localized to Arabidopsis plasma membranes. Analyses of reporter genes performed with AtPMT1 or AtPMT2 promoter sequences showed expression in mature (AtPMT2) or germinating (AtPMT1) pollen grains, as well as in growing pollen tubes, hydathodes, and young xylem cells (both genes). The expression was confirmed with an anti-AtPMT1/AtPMT2 antiserum (?AtPMT1/2) raised against peptides conserved in AtPMT1 and AtPMT2. The physiological roles of the proteins are discussed and related to plant cell wall modifications.

Klepek, Yvonne-Simone; Konrad, Kai R.; Wippel, Kathrin; Hoth, Stefan; Hedrich, Rainer; Sauer, Norbert

2010-01-01

124

Type I interferons modulate the expression of thyroid peroxidase, sodium/iodide symporter, and thyroglobulin genes in primary human thyrocyte cultures.  

PubMed

We evaluated in primary human thyrocyte cultures the effect of interferon (IFN)-alpha and -beta on the expression of thyroid peroxidase (TPO), sodium/iodide symporter (NIS), and thyroglobulin (Tg) as well as T(4) release. Human thyrocyte cultures were carried out with fresh normal thyroid tissue. Gene and protein expression of Tg, TPO, and NIS were assessed by RT-PCR and Western blot analysis after 24, 48, and 72 h of treatment with TSH alone (10 mIU/ml) and in combination with IFN alpha or -beta (10(4) U/ml). IFN inhibited the TSH-stimulated gene expression of Tg, TPO, and NIS in a time-dependent manner without significant differences between IFN alpha and -beta. Moreover, the addition of both type I IFNs clearly reduced the TSH-stimulated protein expression of Tg, TPO, and NIS after 72 h of exposure. Finally, this down-regulation was associated with a reduction of T(4) release by almost 50%. In conclusion, our study shows that both IFN alpha and -beta down-regulate the TSH-stimulated expression of Tg, TPO, and NIS as well as T(4) release. Indeed, the development of hypothyroidism during type I IFN therapy may be related, at least in part, to an abnormal expression and function of key proteins involved in iodine uptake and organification. PMID:15562032

Caraccio, N; Giannini, R; Cuccato, S; Faviana, P; Berti, P; Galleri, D; Dardano, A; Basolo, F; Ferrannini, E; Monzani, F

2004-11-23

125

Structure and substrate-induced conformational changes of the secondary citrate/sodium symporter CitS revealed by electron crystallography.  

PubMed

The secondary Na+/citrate symporter CitS of Klebsiella pneumoniae is the best-characterized member of the 2-hydroxycarboxylate transporter family. The recent projection structure gave insight into its overall structural organization. Here, we present the three-dimensional map of dimeric CitS obtained with electron crystallography. Each monomer has 13 a-helical transmembrane segments; six are organized in a distal helix cluster and seven in the central dimer interface domain. Based on structural analyses and comparison to VcINDY, we propose a molecular model for CitS, assign the helices, and demonstrate the internal structural symmetry. We also present projections of CitS in several conformational states induced by the presence and absence of sodium and citrate as substrates. Citrate binding induces a defined movement of a helices within the distal helical cluster. Based on this, we propose a substrate translocation site and conformational changes that are in agreement with the transport model of ‘‘alternating access’’. PMID:23810698

Kebbel, Fabian; Kurz, Mareike; Arheit, Marcel; Grütter, Markus G; Stahlberg, Henning

2013-07-01

126

Substrate binds in the S1 site of the F253A mutant of LeuT, a neurotransmitter sodium symporter homologue  

SciTech Connect

LeuT serves as the model protein for understanding the relationships between structure, mechanism and pharmacology in neurotransmitter sodium symporters (NSSs). At the present time, however, there is a vigorous debate over whether there is a single high-affinity substrate site (S1) located at the original, crystallographically determined substrate site or whether there are two high-affinity substrates sites, one at the primary or S1 site and the other at a second site (S2) located at the base of the extracellular vestibule. In an effort to address the controversy over the number of high-affinity substrate sites in LeuT, one group studied the F253A mutant of LeuT and asserted that in this mutant substrate binds exclusively to the S2 site and that 1 mM clomipramine entirely ablates substrate binding to the S2 site. Here we study the binding of substrate to the F253A mutant of LeuT using ligand binding and X-ray crystallographic methods. Both experimental methods unambiguously show that substrate binds to the S1 site of the F253A mutant and that binding is retained in the presence of 1 mM clomipramine. These studies, in combination with previous work, are consistent with a mechanism ofr LeuT that involves a single high-affinity substrate binding site.

Wang, Hui; Gouaux, Eric (Oregon HSU)

2012-10-10

127

Identification of Cyclic Adenosine 3?,5?-Monophosphate Response Element Modulator as an Activator of the Human Sodium/Iodide Symporter Upstream Enhancer  

PubMed Central

The lack of Na+/I? symporter (NIS) gene expression in some thyroid cancer patients has been a major hurdle that limits the efficacy of standard radioactive iodide therapy. The molecular mechanism that contributes to low NIS expression is not well understood. Activated NIS gene expression is stimulated by thyroid-stimulating hormone-mediated cAMP/protein kinase A signaling through a NIS upstream enhancer (NUE). The cAMP pathway is also stimulated by forskolin. In the current work, we studied the mechanism of transcriptional activation of NIS in normal thyroid cells and thyroid cancer cells. We identified the cAMP response element modulator (CREM) activator as a new component of the transcription complex that is important for NIS gene expression. The CREM complex is seen in the normal thyroid cells and BRAF (V600E) thyroid cancer cells (BHP 17–10) but is missing in rearranged in transformation/papillary thyroid carcinoma-1 rearrangement thyroid cancer cells (BHP 2–7). This complex is believed to be responsible for the loss of NUE activity and reduced NIS expression in the BHP 2–7 cell line. In BHP 2–7 cells, forskolin stimulated the thyroid-specific transcription factor Pax 8, but CREM activator mRNA did not increase, and this produced a small increase in NUE activity. Ectopic expression of CREM activator enhanced activity of the NUE, indicating that CREM is an essential regulator of NIS gene expression.

Fenton, Mike S.; Marion, Kenneth M.; Hershman, Jerome M.

2008-01-01

128

Enhanced iodide sequestration by 3-biphenyl-5,6-dihydroimidazo[2,1-b]thiazole in sodium/iodide symporter (NIS)-expressing cells.  

PubMed

The ability of the sodium/iodide symporter (NIS) to take up iodide has long provided the basis for cytoreductive gene therapy and cancer treatment with radioiodide. One of the major limitations of this approach is that radioiodide retention in NIS-expressing cells is not sufficient for their destruction. We identified and characterized a small organic molecule capable of increasing iodide retention in HEK293 cells permanently transfected with human NIS cDNA (hNIS-HEK293) and in the rat thyroid-derived cell line FRTL-5. In the presence of 3-biphenyl-4'-yl-5,6-dihydroimidazo[2,1-b]thiazole (ISA1), the transmembrane iodide concentration gradient was increased up to 4.5-fold. Our experiments indicate that the imidazothiazole derivative acts either by inhibiting anion efflux mechanisms, or by promoting the relocation of iodide into subcellular compartments. This new compound is not only an attractive chemical tool to investigate the mechanisms of iodide flux at the cellular level, but also opens promising perspectives in the treatment of cancer after NIS gene transfer. PMID:18470848

Lecat-Guillet, Nathalie; Ambroise, Yves

2008-08-01

129

Cd{sup 2+} versus Zn{sup 2+} uptake by the ZIP8 HCO{sub 3}{sup -}-dependent symporter: Kinetics, electrogenicity and trafficking  

SciTech Connect

The mouse Slc39a8 gene encodes the ZIP8 transporter, which has been shown to be a divalent cation/HCO{sub 3}{sup -} symporter. Using ZIP8 cRNA-injected Xenopus oocyte cultures, we show herein that: [a] ZIP8-mediated cadmium (Cd{sup 2+}) and zinc (Zn{sup 2+}) uptake have V{sub max} values of 1.8 {+-} 0.08 and 1.0 {+-} 0.08 pmol/oocyte/h, and K{sub m} values of 0.48 {+-} 0.08 and 0.26 {+-} 0.09 {mu}M, respectively; [b] ZIP8-mediated Cd{sup 2+} uptake is most inhibited by Zn{sup 2+}, second-best inhibited by Cu{sup 2+}, Pb{sup 2+} and Hg{sup 2+}, and not inhibited by Mn{sup 2+} or Fe{sup 2+}; and [c] electrogenicity studies demonstrate an influx of two HCO{sub 3}{sup -} anions per one Cd{sup 2+} (or one Zn{sup 2+}) cation, i.e. electroneutral complexes. Using Madin-Darby canine kidney (MDCK) polarized epithelial cells retrovirally infected with ZIP8 cDNA and tagged with hemagglutinin at the C-terminus, we show that-similar to ZIP4-the ZIP8 eight-transmembrane protein is largely internalized during Zn{sup 2+} homeostasis, but moves predominantly to the cell surface membrane (trafficking) under conditions of Zn{sup 2+} depletion.

Liu Zhiwei [Department of Environmental Health and Center for Environmental Genetics (CEG), University of Cincinnati Medical Center, P.O. Box 670056, Cincinnati, OH 45267-0056 (United States); Li Hong; Soleimani, Manoocher [Department of Internal Medicine, Division of Nephrology and Hypertension, University Cincinnati Medical Center, Cincinnati, OH 45267-0056 (United States); Girijashanker, Kuppuswami; Reed, Jodie M.; He Lei; Dalton, Timothy P. [Department of Environmental Health and Center for Environmental Genetics (CEG), University of Cincinnati Medical Center, P.O. Box 670056, Cincinnati, OH 45267-0056 (United States); Nebert, Daniel W. [Department of Environmental Health and Center for Environmental Genetics (CEG), University of Cincinnati Medical Center, P.O. Box 670056, Cincinnati, OH 45267-0056 (United States)], E-mail: dan.nebert@uc.edu

2008-01-25

130

Radioiodide imaging and radiovirotherapy of multiple myeloma using VSV(?51)-NIS, an attenuated vesicular stomatitis virus encoding the sodium iodide symporter gene  

PubMed Central

Multiple myeloma is a radiosensitive malignancy that is currently incurable. Here, we generated a novel recombinant vesicular stomatitis virus [VSV(?51)-NIS] that has a deletion of methionine 51 in the matrix protein and expresses the human sodium iodide symporter (NIS) gene. VSV(?51)-NIS showed specific oncolytic activity against myeloma cell lines and primary myeloma cells and was able to replicate to high titers in myeloma cells in vitro. Iodide uptake assays showed accumulation of radioactive iodide in VSV(?51)-NIS–infected myeloma cells that was specific to the function of the NIS transgene. In bg/nd/xid mice with established subcutaneous myeloma tumors, administration of VSV(?51)-NIS resulted in high intratumoral virus replication and tumor regression. VSV-associated neurotoxicity was not observed. Intratumoral spread of the infection was monitored noninvasively by serial gamma camera imaging of 123I-iodide biodistribution. Dosimetry calculations based on these images pointed to the feasibility of combination radiovirotherapy with VSV(?51)-NIS plus 131I. Immunocompetent mice with syngeneic 5TGM1 myeloma tumors (either subcutaneous or orthotopic) showed significant enhancements of tumor regression and survival when VSV(?51)-NIS was combined with 131I. These results show that VSV(?51)-NIS is a safe oncolytic agent with significant therapeutic potential in multiple myeloma.

Goel, Apollina; Carlson, Stephanie K.; Classic, Kelly L.; Greiner, Suzanne; Naik, Shruthi; Power, Anthony T.; Bell, John C.

2007-01-01

131

Switching from MAPK-dependent to MAPK-independent repression of the sodium-iodide symporter in 2D and 3D cultured normal thyroid cells.  

PubMed

Loss of sodium-iodide symporter (NIS) expression in thyroid tumour cells primarily caused by constitutive MAPK pathway activation is often refractory to small molecule MAPK inhibitors. Suggested mechanisms are rebound MAPK signalling and activation of alternative signalling pathways. Here we provide evidence that failure to recover down-regulated NIS by MEK inhibition is not specific to tumour cells. NIS mRNA levels remained repressed in TSH-stimulated primary thyroid cells co-treated with epidermal growth factor (EGF) and pan-MEK inhibitor U0126 in the presence of 5% fetal bovine serum or, independently of serum, in 3D cultured thyroid follicles. This led to inhibited iodide transport and iodination. In contrast, U0126 restituted thyroglobulin synthesis in EGF-treated follicular cells. Serum potentiated TSH-stimulated NIS expression in 2D culture. U0126 blocked down-regulation of NIS only in serum-starved cells with a diminished TSH response. Together, this suggests that morphogenetic signals modify the expression of NIS and recovery response to MEK inhibition. PMID:23969277

Ingeson-Carlsson, Camilla; Nilsson, Mikael

2013-08-19

132

Induction of sodium iodide symporter gene and molecular characterisation of HNF3?/FoxA2, TTF-1 and C/EBP? in thyroid carcinoma cells  

PubMed Central

Thyroid carcinoma cells often do not express thyroid-specific genes including sodium iodide symporter (NIS), thyroperoxidase (TPO), thyroglobulin (TG), and thyrotropin-stimulating hormone receptor (TSHR). Treatment of thyroid carcinoma cells (four papillary and two anaplastic cell lines) with histone deacetylase inhibitors (SAHA or VPA) modestly induced the expression of the NIS gene. The promoter regions of the thyroid-specific genes contained binding sites for hepatocyte nuclear factor 3 ? (HNF3?)/forkhead box A2 (FoxA2), thyroid transcription factor 1 (TTF-1), and CCAAT/enhancer binding protein ? (C/EBP?). Quantitative reverse transcription-polymerase chain reaction (RT–PCR) showed decreased expression of HNF3?/FoxA2 and TTF-1 mRNA in papillary thyroid carcinoma cell lines, when compared with normal thyroid cells. Forced expression of these genes in papillary thyroid carcinoma cells inhibited their growth. Furthermore, the CpG island in the promoter region of HNF3?/FoxA2 was aberrantly methylated; and treatment with 5-aza-2-deoxycytidine (5-Az) induced its expression. Immunohistochemical staining showed that C/EBP? was localised in the nucleus in normal thyroid cells but was detected in the cytoplasm in papillary thyroid carcinoma cells. Subcellular fractionation of papillary thyroid carcinoma cell lines also demonstrated high levels of expression of C/EBP? in the cytoplasm, suggesting that a large proportion of C/EBP? protein is inappropriately localised in the cytoplasm. In summary, these findings reveal novel abnormalities in thyroid carcinoma cells

Akagi, T; Luong, Q T; Gui, D; Said, J; Selektar, J; Yung, A; Bunce, C M; Braunstein, G D; Koeffler, H P

2008-01-01

133

Non-apoptotic concentrations of prodigiosin (H+/Cl- symporter) inhibit the acidification of lysosomes and induce cell cycle blockage in colon cancer cells.  

PubMed

Prodigiosin (PG) is a bacterial red pigment with interesting immunosuppressive and apoptotic properties that have been partly attributed to its ability to uncouple V-ATPase through the promotion of the H+/Cl- symporter. In the present study, we investigate the effect of non-apoptotic concentrations of PG on the lysosomal-pH and on cell cycle progression in colon cancer cells. Lysosomal-pH was tested in DLD-1 cells using acridine orange vital staining. Orange granules, indicative of acidified lysosomes, decreased significantly in cells treated with 25 nM of PG for 1/2 h, and disappeared completely at 100 nM. This suggests that PG can induce lysosomal alkalinization without any apparent cytotoxic effect. Cell cycle progression was analysed in HT29 cells and we found that PG induces a blockage in the G1 phase. This blockage correlates with p21(WAF1/CIP1) induction, and it can be triggered either dependently or independently of p53. In conclusion, the reversible increase in lysosomal-pH and cytosol acidification induced by non-apoptotic concentrations of PG in colon cancer cells, suggests that the apoptotic process induced by PG can not be solely explained by changes in intracellular pH. The effect of intracellular acidification on cell cycle arrest must be analysed more exactly. PMID:16126233

Castillo-Avila, Wilmar; Abal, Miguel; Robine, Sylvie; Pérez-Tomás, Ricardo

2005-08-29

134

Saccharomyces cerevisiae glycerol/H+ symporter Stl1p is essential for cold/near-freeze and freeze stress adaptation. A simple recipe with high biotechnological potential is given  

PubMed Central

Background Freezing is an increasingly important means of preservation and storage of microbial strains used for many types of industrial applications including food processing. However, the yeast mechanisms of tolerance and sensitivity to freeze or near-freeze stress are still poorly understood. More knowledge on this regard would improve their biotechnological potential. Glycerol, in particular intracellular glycerol, has been assigned as a cryoprotectant, also important for cold/near-freeze stress adaptation. The S. cerevisiae glycerol active transporter Stl1p plays an important role on the fast accumulation of glycerol. This gene is expressed under gluconeogenic conditions, under osmotic shock and stress, as well as under high temperatures. Results We found that cells grown on STL1 induction medium (YPGE) and subjected to cold/near-freeze stress, displayed an extremely high expression of this gene, also visible at glycerol/H+ symporter activity level. Under the same conditions, the strains harbouring this transporter accumulated more than 400 mM glycerol, whereas the glycerol/H+ symporter mutant presented less than 1 mM. Consistently, the strains able to accumulate glycerol survive 25-50% more than the stl1? mutant. Conclusions In this work, we report the contribution of the glycerol/H+ symporter Stl1p for the accumulation and maintenance of glycerol intracellular levels, and consequently cell survival at cold/near-freeze and freeze temperatures. These findings have a high biotechnological impact, as they show that any S. cerevisiae strain already in use can become more resistant to cold/freeze-thaw stress just by simply adding glycerol to the broth. The combination of low temperatures with extracellular glycerol will induce the transporter Stl1p. This solution avoids the use of transgenic strains, in particular in food industry.

2010-01-01

135

Linkage of familial euthyroid goiter to the multinodular goiter-1 locus and exclusion of the candidate genes thyroglobulin, thyroperoxidase, and Na+/I- symporter.  

PubMed

Iodine deficiency is the most important etiological factor for euthyroid endemic goiter. However, family and twin pair studies also indicate a genetic predisposition for euthyroid simple goiter. In hypothyroid goiters several molecular defects in the thyroglobulin (TG), thyroperoxidase (TPO), and Na+/I- symporter (NIS) genes have been identified. The TSH receptor with its central role for thyroid function and growth is also a strong candidate gene. Therefore, we investigated a proposita with a relapsing euthyroid goiter and her family, in which several members underwent thyroidectomy for euthyroid goiter. Sequence analysis of the complementary DNA (cDNA) of the TPO and TSH receptor genes revealed several previously reported polymorphisms. As it is not possible to exclude a functional relevance for all polymorphisms, we opted for linkage analysis with microsatellite markers to investigate whether the candidate genes are involved in the pathogenesis of euthyroid goiter. The markers for the genes TG, TPO, and NIS gave two-point and multipoint logarithm of odds score analysis scores that were negative or below 1 for all assumed recombination fractions. As no significant evidence of linkage was found, we conclude that these candidate genes can be excluded as a major cause of the euthyroid goiters in this family. In contrast, we have found evidence for linkage of familial euthyroid goiter to the recently identified locus for familial multinodular nontoxic goiter (MNG-1) on chromosome 14q. The haplotype cosegregates clearly with familial euthyroid goiter. Our results provide the first confirmation for MNG-1 as a locus for nontoxic goiter. PMID:10523025

Neumann, S; Willgerodt, H; Ackermann, F; Reske, A; Jung, M; Reis, A; Paschke, R

1999-10-01

136

Sodium Iodide Symporter (NIS)-Mediated Radionuclide (131I, 188Re) Therapy of Liver Cancer After Transcriptionally Targeted Intratumoral in Vivo NIS Gene Delivery  

PubMed Central

Abstract We reported the therapeutic efficacy of 131I in hepatocellular carcinoma (HCC) cells stably expressing the sodium iodide symporter (NIS) under the control of the tumor-specific ?-fetoprotein (AFP) promoter. In the current study we investigated the efficacy of adenovirus-mediated in vivo NIS gene transfer followed by 131I and 188Re administration for the treatment of HCC xenografts. We used a replication-deficient adenovirus carrying the human NIS gene linked to the mouse AFP promoter (Ad5-AFP-NIS) for in vitro and in vivo NIS gene transfer. Functional NIS expression was confirmed by in vivo ?-camera imaging, followed by analysis of NIS protein and mRNA expression. Human HCC (HepG2) cells infected with Ad5-AFP-NIS concentrated 50% of the applied activity of 125I, which was sufficiently high for a therapeutic effect in an in vitro clonogenic assay. Four days after intratumoral injection of Ad5-AFP-NIS (3×109 plaque-forming units) HepG2 xenografts accumulated 14.5% injected dose (ID)/g 123I with an effective half-life of 13?hr (tumor-absorbed dose, 318?mGy/MBq 131I). In comparison, 9.2% ID/g 188Re was accumulated in tumors with an effective half-life of 12.8?hr (tumor-absorbed dose, 545?mGy/MBq). After adenovirus-mediated NIS gene transfer in HepG2 xenografts administration of a therapeutic dose of 131I or 188Re (55.5?MBq) resulted in a significant delay in tumor growth and improved survival without a significant difference between 188Re and 131I. In conclusion, a therapeutic effect of 131I and 188Re was demonstrated in HepG2 xenografts after tumor-specific adenovirus-mediated in vivo NIS gene transfer.

Klutz, Kathrin; Willhauck, Michael J.; Wunderlich, Nathalie; Zach, Christian; Anton, Martina; Senekowitsch-Schmidtke, Reingard; Goke, Burkhard

2011-01-01

137

Determination of the optimal time for radioiodine therapy in anaplastic thyroid carcinoma using the adenovirus-mediated transfer of sodium iodide symporter gene.  

PubMed

Gene therapy using human sodium iodide symporter (hNIS) and radioiodine has been considered promising in a variety of gene therapy trials. However, the optimal timing of radioiodine application following hNIS gene transfer remains unknown. The present study aimed to investigate the serial expression of hNIS following adenovirus-mediated hNIS gene transfer into anaplastic thyroid carcinoma (ARO) to determine the optimal timing of radioiodine application. Recombinant adenovirus encoding the hNIS gene (rAd-hNIS) was generated using a homologous recombination reaction. The iodine uptake of rAd-hNIS?transfected ARO cells gradually increased until 120 min post?125I application but the fold increase, reflecting the relative uptake of rAd-hNIS?transfected compared to non?transfected ARO cells, reached plateau at 60 min post?125I application. For the in vivo analysis, rAd-hNIS was injected intratumorally into ARO cell xenografts in the thighs of nude mice (n=12). Two, 3, 4 and 6 days after rAd-hNIS injection, ??scintigraphic images were obtained 60 min following injection of 5.5 MBq of 131I intraperitoneally. Treated/non-treated (T/NT) xenograft count ratios were the highest at day 2 post?rAd-hNIS injection (2.85±0.61), and gradually decreased thereafter (2.54±0.65, 2.31±0.42 and 2.18±0.90 at days 3, 4 and 6 post?rAd-hNIS injection, respectively). Real?time polymerase chain reaction (RT-PCR) and immunohistochemical staining demonstrated that hNIS expression was the highest at day 2 following rAd-hNIS injection. In conclusion, the optimal timing for radioiodine administration is day 2 after adenovirus-mediated hNIS gene transfer into anaplastic thyroid carcinoma. PMID:23404348

So, Young; Lee, Yong Jin; Lee, Won Woo; Chung, June-Key

2013-02-06

138

Combined Cerenkov luminescence and nuclear imaging of radioiodine in the thyroid gland and thyroid cancer cells expressing sodium iodide symporter: initial feasibility study.  

PubMed

Radioiodine (RI) such as (131)I or (124)I, can generate luminescent emission and be detected with an optical imaging (OI) device. To evaluate the possibility of a novel Cerenkov luminescence imaging (CLI) for application in thyroid research, we performed feasibility studies of CLI by RI in the thyroid gland and human anaplastic thyroid carcinoma cells expressing sodium iodide symporter gene (ARO-NIS). For in vitro study, FRTL-5 and ARO-NIS were incubated with RI, and the luminometric and CLI intensity was measured with luminometer and OI device. Luminescence intensity was compared with the radioactivity measured with ?-counter. In vivo CLI of the thyroid gland was performed in mice after intravenous injection of RI with and without thyroid blocking. Mice were implanted with ARO-NIS subcutaneously, and CLI was performed with injection of (124)I. Small animal PET or ?-camera imaging was also performed. CLI intensities of thyroid gland and ARO-NIS were quantified, and compared with the radioactivities measured from nuclear images (NI). Luminometric assay and OI confirmed RI uptake in the cells in a dose-dependent manner, and luminescence intensity was well correlated with radioactivity of the cells. CLI clearly demonstrated RI uptake in thyroid gland and xenografted ARO-NIS cells in mice, which was further confirmed by NI. A strong positive correlation was observed between CLI intensity and radioactivity assessed by NI. We successfully demonstrated dual molecular imaging of CLI and NI using RI both in vitro and in vivo. CLI can provide a new OI strategy in preclinical thyroid studies. PMID:21551958

Jeong, Shin Young; Hwang, Mi-Hye; Kim, Jung Eun; Kang, Sungmin; Park, Jeong Chan; Yoo, Jeongsoo; Ha, Jeoung-Hee; Lee, Sang-Woo; Ahn, Byeong-Cheol; Lee, Jaetae

2011-05-07

139

Perchlorate transport and inhibition of the sodium iodide symporter measured with the yellow fluorescent protein variant YFP-H148Q/I152L.  

PubMed

Perchlorate is an environmental contaminant that impairs thyroid function by interacting with the sodium iodide symporter (NIS), the transporter responsible for iodide uptake in the thyroid gland. Perchlorate is well known as a competitive inhibitor of iodide transport by NIS, and recent evidence demonstrates that NIS can also transport perchlorate. In this study, we evaluated the yellow fluorescent protein (YFP) variant YFP-H148Q/I152L, as a genetically encodable biosensor of intracellular perchlorate concentration monitored by real-time fluorescence microscopy. Fluorescence of recombinant YFP-H148Q/I152L was suppressed by perchlorate and iodide with similar affinities of 1.2 mM and 1.6 mM, respectively. Perchlorate suppressed YFP-H148Q/I152L fluorescence in FRTL-5 thyroid cells and NIS-expressing COS-7 cells, but had no effect on COS-7 cells lacking NIS. Fluorescence changes in FRTL-5 cells were Na+-dependent, consistent with the Na+-dependence of NIS activity. Perchlorate uptake in FRTL-5 cells resulted in 10-fold lower intracellular concentrations than iodide uptake, and was characterized by a higher affinity (K(m) 4.6 microM for perchlorate and 34.8 muM for iodide) and lower maximal velocity (V(max) 6.8 microM/s for perchlorate and 39.5 microM/s for iodide). Perchlorate also prevented iodide-induced changes in YFP-H148Q/I152L fluorescence in FRTL-5 cells, with half-maximal inhibition occurring at 1.1-1.6 muM. In conclusion, YFP-H148Q/I152L detects perchlorate accumulation by thyroid and other NIS-expressing cells, and reveals differences in the kinetics of perchlorate versus iodide transport by NIS. PMID:20005887

Cianchetta, Stefano; di Bernardo, Julie; Romeo, Giovanni; Rhoden, Kerry J

2009-12-18

140

Sodium iodide symporter (NIS)-mediated radionuclide ((131)I, (188)Re) therapy of liver cancer after transcriptionally targeted intratumoral in vivo NIS gene delivery.  

PubMed

We reported the therapeutic efficacy of (131)I in hepatocellular carcinoma (HCC) cells stably expressing the sodium iodide symporter (NIS) under the control of the tumor-specific ?-fetoprotein (AFP) promoter. In the current study we investigated the efficacy of adenovirus-mediated in vivo NIS gene transfer followed by (131)I and (188)Re administration for the treatment of HCC xenografts. We used a replication-deficient adenovirus carrying the human NIS gene linked to the mouse AFP promoter (Ad5-AFP-NIS) for in vitro and in vivo NIS gene transfer. Functional NIS expression was confirmed by in vivo ?-camera imaging, followed by analysis of NIS protein and mRNA expression. Human HCC (HepG2) cells infected with Ad5-AFP-NIS concentrated 50% of the applied activity of (125)I, which was sufficiently high for a therapeutic effect in an in vitro clonogenic assay. Four days after intratumoral injection of Ad5-AFP-NIS (3×10(9) plaque-forming units) HepG2 xenografts accumulated 14.5% injected dose (ID)/g (123)I with an effective half-life of 13?hr (tumor-absorbed dose, 318?mGy/MBq (131)I). In comparison, 9.2% ID/g (188)Re was accumulated in tumors with an effective half-life of 12.8?hr (tumor-absorbed dose, 545?mGy/MBq). After adenovirus-mediated NIS gene transfer in HepG2 xenografts administration of a therapeutic dose of (131)I or (188)Re (55.5?MBq) resulted in a significant delay in tumor growth and improved survival without a significant difference between (188)Re and (131)I. In conclusion, a therapeutic effect of (131)I and (188)Re was demonstrated in HepG2 xenografts after tumor-specific adenovirus-mediated in vivo NIS gene transfer. PMID:21488714

Klutz, Kathrin; Willhauck, Michael J; Wunderlich, Nathalie; Zach, Christian; Anton, Martina; Senekowitsch-Schmidtke, Reingard; Göke, Burkhard; Spitzweg, Christine

2011-06-28

141

Insertion of the human sodium iodide symporter to facilitate deep tissue imaging does not alter oncolytic or replication capability of a novel vaccinia virus  

PubMed Central

Introduction Oncolytic viruses show promise for treating cancer. However, to assess therapeutic efficacy and potential toxicity, a noninvasive imaging modality is needed. This study aimed to determine if insertion of the human sodium iodide symporter (hNIS) cDNA as a marker for non-invasive imaging of virotherapy alters the replication and oncolytic capability of a novel vaccinia virus, GLV-1h153. Methods GLV-1h153 was modified from parental vaccinia virus GLV-1h68 to carry hNIS via homologous recombination. GLV-1h153 was tested against human pancreatic cancer cell line PANC-1 for replication via viral plaque assays and flow cytometry. Expression and transportation of hNIS in infected cells was evaluated using Westernblot and immunofluorescence. Intracellular uptake of radioiodide was assessed using radiouptake assays. Viral cytotoxicity and tumor regression of treated PANC-1tumor xenografts in nude mice was also determined. Finally, tumor radiouptake in xenografts was assessed via positron emission tomography (PET) utilizing carrier-free 124I radiotracer. Results GLV-1h153 infected, replicated within, and killed PANC-1 cells as efficiently as GLV-1h68. GLV-1h153 provided dose-dependent levels of hNIS expression in infected cells. Immunofluorescence detected transport of the protein to the cell membrane prior to cell lysis, enhancing hNIS-specific radiouptake (P < 0.001). In vivo, GLV-1h153 was as safe and effective as GLV-1h68 in regressing pancreatic cancer xenografts (P < 0.001). Finally, intratumoral injection of GLV-1h153 facilitated imaging of virus replication in tumors via 124I-PET. Conclusion Insertion of the hNIS gene does not hinder replication or oncolytic capability of GLV-1h153, rendering this novel virus a promising new candidate for the noninvasive imaging and tracking of oncolytic viral therapy.

2011-01-01

142

Tumor Necrosis Factor, Ceramide, Transforming Growth Factor 1, and Aging Reduce Na+\\/I- Symporter Messenger Ribonucleic Acid Levels in FRTL-5 Cells  

Microsoft Academic Search

Iodide uptake, which is necessary for thyroid hormone synthesis, can be inhibited by aging, withdrawal of TSH, or increased tumor necrosis factor (TNF) and transforming growth factor (TGF)-b1 levels resulting from the nonthyroid illness syndrome. TNF induces recep- tor-mediated activation of sphingomyelinase, which converts sphin- gomyelin to ceramide, a mediator of TNF actions. Thyroid follicular cells transport iodide from blood

A. EUGENE PEKARY; JEROME M. HERSHMAN; LORETTA BERG

1998-01-01

143

PROF_ PAT 1.3: Updated database of patterns used to detect local similarities  

Microsoft Academic Search

Motivation: When analysing novel protein sequences, it is now essential to extend search strategies to include a range of 'secondary' databases. Pattern databases have become vital tools for identifying distant relationships in sequences, and hence for predicting protein function and structure. The main drawback of such methods is the relatively small representation of proteins in trial samples at the time

Alexander G. Bachinsky; Anatoly S. Frolov; Andrey N. Naumochkin; Lily Ph. Nizolenko; Andrey A. Yarigin

2000-01-01

144

PAT1.1; Pinellas Action Tracking System; Tracks Audit Findings and Corrective Actions  

SciTech Connect

PAT was derived from a system that began at the Rocky Flats Plant and was further enhanced at the Mound Plant. Pinellas Plant obtained this system in 1990 to track Tiger Team Findings; it has been expanded to include new modules which encompass a wide range of related functions. Functionality includes tracking of findings and associated corrective actions from various sources such as line operations, self-assessments, oversight assessments, and external organizations. Other functionality includes Management Walk-About tracking, NEPA prioritization, Occurrence/incident Report corrective action tracking, and Management Action Item Tracking. The system utilizes state of the art relational database technology with pop-up windows for table lookups and entry of descriptive text. Standards such as assessment identification numbers, area designations, and finding category codes have been developed to provide enhanced query capabilities and the ability to group findings for trending purposes on a plant-wide basis.

Mellican, P.L. [Martin Marietta Speciality Components, Largo, FL (United States)

1993-04-09

145

In vivo long-term imaging and radioiodine therapy by sodium-iodide symporter gene expression using a lentiviral system containing ubiquitin C promoter.  

PubMed

To establish stable and long-term gene expression in vitro and in vivo, we developed a lentiviral vector system carrying sodium iodide symporter (hNIS) gene under UbC promoter, and transfected this into a colon cancer cell line. The in vitro and in vivo kinetics of radioiodine and [99mTc]-pertechnetate were then investigated, and the therapeutic effect of 1-131 was evaluated in this system. The hNIS gene was transferred into CT26 cells using lentivirus containing UbC promoter. In vitro iodide uptake and efflux were measured in CT26-hNIS cells at various time points. In addition, scintigraphic images were acquired at 30 min after injecting [99mTc]-pertechnetate i.p. into Balb/C mice for 27 days after CT26-hNIS induction. Biodistribution studies were performed at 10 and 30 min and at 1.5, 6 and 24 h after [99mTc]-pertechnetate injections, and the therapeutic effects of radioiodine were investigated by measuring tumor size using a caliper or by quantifying tumor radioactivity levels in scintigraphic images. The iodide uptakes of CT26-hNIS tumors were 10-fold greater than those of CT26 tumors. In addition, iodide uptake was completely blocked by 100 microM potassium perchlorate. The accumulation of [99mTc]-pertechnetate in hNIS expressing tumor cells was found to be positively related to tumor growth. In biodistribution studies, the %ID/g values of CT26-hNIS were 84.0 +/- 4.5 at 1.5 h and 40.8 +/- 3.9 at 24 h and these were approximately 60 times greater than those of CT26 at these time points. Tumor growth in mice treated with 131I was retarded until 46 days post-tumor challenge. The devised lentiviral vector system carrying hNIS controlled by UbC promoter was found to be suitable for the long-term monitoring and radionuclide therapy of cancer in living organism. PMID:17611400

Kim, Hyun Joo; Jeon, Yong Hyun; Kang, Joo Hyun; Lee, Yong Jin; Kim, Kwang Il; Chung, Hye Kyung; Jeong, Jae Min; Lee, Dong Soo; Lee, Myung Chul; Chung, June-Key

2007-07-01

146

Molecular dissection of membrane-transport proteins: mass spectrometry and sequence determination of the galactose-H+ symport protein, GalP, of Escherichia coli and quantitative assay of the incorporation of [ring-2-13C]histidine and (15)NH(3).  

PubMed

The molecular mass of the galactose-H(+) symport protein GalP, as its histidine-tagged derivative GalP(His)(6), has been determined by electrospray MS (ESI-MS) with an error of <0.02%. One methionine residue, predicted to be present from the DNA sequence, was deduced to be absent. This is a significant advance on the estimation of the molecular masses of membrane-transport proteins by SDS/PAGE, where there is a consistent under-estimation of the true molecular mass due to anomalous electrophoretic migration. Addition of a size-exclusion chromatography step after Ni(2+)-nitrilotriacetate affinity purification was essential to obtain GalP(His)(6) suitable for ESI-MS. Controlled trypsin, trypsin+chymotrypsin and CNBr digestion of the protein yielded peptide fragments suitable for ESI-MS and tandem MS analysis, and accurate mass determination of the derived fragments resulted in identification of 82% of the GalP(His)(6) protein. Tandem MS analysis of selected peptides then afforded 49% of the actual amino acid sequence of the protein; the absence of the N-terminal methionine was confirmed. Matrix-assisted laser-desorption ionization MS allowed identification of one peptide that was not detected by ESI-MS. All the protein/peptide mass and sequence determinations were in accord with the predictions of amino acid sequence deduced from the DNA sequence of the galP gene. [ring-2-(13)C]Histidine was incorporated into GalP(His)(6) in vivo, and ESI-MS analysis enabled the measurement of a high (80%) and specific incorporation of label into the histidine residues in the protein. MS could also be used to confirm the labelling of the protein by (15)NH(3) (93% enrichment) and [(19)F]tryptophan (83% enrichment). Such MS measurements will serve in the future analysis of the structures of membrane-transport proteins by NMR, and of their topology by indirect techniques. PMID:11931651

Venter, Henrietta; Ashcroft, Alison E; Keen, Jeffrey N; Henderson, Peter J F; Herbert, Richard B

2002-04-15

147

Analysis of human sodium/iodide symporter, thyroid transcription factor-1, and paired-box-protein-8 gene expression in benign thyroid diseases.  

PubMed

The ability to concentrate iodide, a fundamental property of normally functioning thyroid tissue, is altered in various thyroid diseases. Given the critical role of the Na+/I- symporter (NIS) in controlling iodide access to the thyroid gland, altered expression of NIS may be responsible, at least in part, for an enhanced or diminished capacity to concentrate iodide. In this study, we used Northern blot analysis, a newly established quantitative polymerase chain reaction (PCR) assay and in addition hNIS-directed immunohistochemical analysis to assess the levels of hNIS mRNA and protein expression in various localized and diffuse benign thyroid abnormalities, including Graves' disease (GD), scintigraphically cold solitary benign thyroid nodule (CBTN), nontoxic multinodular goiter (NMNG), solitary autonomously functioning thyroid nodule (AFTN), and mild diffuse iodine deficiency goiter (IDG). In addition, in view of the recent identification of putative binding sites for the transcription factors thyroid transcription factor-1 (TTF-1) and human paired-box-protein-8 (Pax-8) in the human NIS gene promoter, we used reverse transcriptase-polymerase chain reaction (RT-PCR) to assess in these same samples the levels of TTF-1 and Pax-8 gene expression. Northern blot analysis revealed high levels of hNIS gene expression in thyroid specimens derived from patients with GD and AFTN. In contrast, levels of hNIS mRNA expression were moderate in NMNG, low in diffuse IDG, and very low in CBTN. Quantitative RT-PCR analysis of hNIS mRNA transcripts revealed variable but generally low levels of hNIS gene expression in IDG and NMNG, and undetectable or very low levels of hNIS mRNA in all scintigraphically CBTN studied. In contrast, markedly elevated levels of hNIS mRNA transcripts were detected in active GD (up to 17-fold) and AFTN (up to 25-fold). Immunohistochemical analysis revealed abundant hNIS protein expression by thyroid follicular cells in GD, moderate and heterogeneous levels in NMNG, and very low levels in CBTN. hNIS mRNA levels were correlated with TTF-1 and Pax-8 gene expression in GD and, to a lesser degree, in AFTN, NMNG, and IDG, but not in CBTN. In general, hNIS gene expression was more closely correlated with TTF-1 as compared to Pax-8 gene expression. In conclusion, the abundance of hNIS mRNA and protein expression in a broad range of benign thyroid pathologies correlated well with their functional state as assessed by thyroid scintigraphy. In addition to TTF-1 and Pax-8, other transcription factors and enhancer elements may contribute to regulation of NIS gene promoter activity. PMID:10365677

Joba, W; Spitzweg, C; Schriever, K; Heufelder, A E

1999-05-01

148

An increase in essential amino acid availability upregulates amino acid transporter expression in human skeletal muscle  

PubMed Central

Essential amino acids (EAA) stimulate skeletal muscle mammalian target of rapamycin complex 1 (mTORC1) signaling and protein synthesis. It has recently been reported that an increase in amino acid (AA) transporter expression during anabolic conditions is rapamycin-sensitive. The purpose of this study was to determine whether an increase in EAA availability increases AA transporter expression in human skeletal muscle. Muscle biopsies were obtained from the vastus lateralis of seven young adult subjects (3 male, 4 female) before and 1–3 h after EAA ingestion (10 g). Blood and muscle samples were analyzed for leucine kinetics using stable isotopic techniques. Quantitative RT-PCR, and immunoblotting were used to determine the mRNA and protein expression, respectively, of AA transporters and members of the general AA control pathway [general control nonrepressed (GCN2), activating transcription factor (ATF4), and eukaryotic initiation factor (eIF2) ?-subunit (Ser52)]. EAA ingestion increased blood leucine concentration, delivery of leucine to muscle, transport of leucine from blood into muscle, intracellular muscle leucine concentration, ribosomal protein S6 (Ser240/244) phosphorylation, and muscle protein synthesis. This was followed with increased L-type AA transporter (LAT1), CD98, sodium-coupled neutral AA transporter (SNAT2), and proton-coupled amino acid transporter (PAT1) mRNA expression at 1 h (P < 0.05) and modest increases in LAT1 protein expression (3 h post-EAA) and SNAT2 protein expression (2 and 3 h post-EAA, P < 0.05). Although there were no changes in GCN2 expression and eIF2? phosphorylation, ATF4 protein expression reached significance by 2 h post-EAA (P < 0.05). We conclude that an increase in EAA availability upregulates human skeletal muscle AA transporter expression, perhaps in an mTORC1-dependent manner, which may be an adaptive response necessary for improved AA intracellular delivery.

Drummond, Micah J.; Glynn, Erin L.; Fry, Christopher S.; Timmerman, Kyle L.; Volpi, Elena

2010-01-01

149

Expression cloning in yeast of a cDNA encoding a broad specificity amino acid permease from Arabidopsis thaliana.  

PubMed Central

To study amino acid transport in plants at the molecular level, we have isolated an amino acid permease cDNA from Arabidopsis thaliana by complementation of a yeast mutant defective in proline uptake with a cDNA. The predicted polypeptide of 53 kDa is highly hydrophobic with 12 putative membrane-spanning regions and shows no significant homologies to other known transporters. Expression of the cDNA enables the yeast mutant to take up L-[14C]proline. Competition studies argue for a broad but stereospecific substrate recognition by the permease, which resembles neutral or general amino acid transport systems from Chlorella and higher plants. Both pH dependence and inhibition by protonophores are consistent with a proton symport mechanism. Images Fig. 1

Frommer, W B; Hummel, S; Riesmeier, J W

1993-01-01

150

Evolutionary origin of amino acid transporter families SLC32, SLC36 and SLC38 and physiological, pathological and therapeutic aspects.  

PubMed

About 25% of all solute carriers (SLCs) are likely to transport amino acids as their primary substrate. One of the major phylogenetic clusters of amino acid transporters from the SLC family is the ?-family, which is part of the PFAM APC clan. The ?-family includes three SLC families, SLC32, SLC36 and SLC38 with one, four and eleven members in humans, respectively. The most well characterized genes within these families are the vesicular inhibitory amino acid transporter (VIAAT, SLC32A1), PAT1 (SLC36A1), PAT2 (SLC36A2), PAT4 (SLC36A4), SNAT1 (SLC38A1), SNAT2 (SLC38A2), SNAT3 (SLC38A3), and SNAT4 (SLC38A4). Here we review the structural characteristics and functional role of these transporters. We also mined the complete protein sequence datasets for nine different genomes to clarify the evolutionary history of the ?-family of transporters. We show that all three main branches of the this family are found as far back as green algae suggesting that genes from these families existed in the early eukaryote before the split of animals and plants and that they are present in most animal species. We also address the potential of further drug development within this field highlighting the important role of these transporters in neurotransmission and transport of amino acids as nutrients. PMID:23506890

Schiöth, Helgi B; Roshanbin, Sahar; Hägglund, Maria G A; Fredriksson, Robert

151

NF-kappaB p65 subunit mediates lipopolysaccharide-induced Na(+)/I(-) symporter gene expression by involving functional interaction with the paired domain transcription factor Pax8.  

PubMed

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

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

2010-07-28

152

Combined E7-dendritic cell-based immunotherapy and human sodium/iodide symporter radioiodine gene therapy with monitoring of antitumor effects by bioluminescent imaging in a mouse model of uterine cervical cancer.  

PubMed

Using a uterine cervical cancer cell line expressing human papillomavirus (HPV) 16 E7 antigen and bioluminescent imaging (BLI), we evaluated the therapeutic potential of combined immunotherapy using transfected dendritic cells (DC-E7) and human sodium/iodide symporter (hNIS) radioiodine gene therapy in a xenograft animal cancer model. Dendritic cells expressing either E7 antigen (DC-E7) or no-insert (DC-no insert) were made for immunization materials, and murine uterine cervical cancer cell line coexpressing E7, firefly luciferase, hNIS, and EGFP genes (TC-1/FNG) were prepared for the animal tumor model. C57BL/6 mice were divided into five therapy groups (phosphate-buffered saline [PBS], DC-no insert, DC-E7, I-131, and DC-E7+I-131 groups). Single therapy with either DC-E7 or I-131 induced greater retardation in tumor growth compared with PBS or DC-no insert groups, and it resulted in some tumor-free mice (DC-E7 and I-131 groups, 40% and 20%, respectively). Combination therapy with DC-E7 and I-131 dramatically inhibited tumor growth, thus causing complete disappearance of tumors in all mice, and these effects were further confirmed by BLI in vivo. In conclusion, complete disappearance of the tumor was achieved with combined DC-E7 vaccination and hNIS radioiodine gene therapy in a mouse model with E7-expressing uterine cervical cancer, and serial BLIs successfully demonstrated antitumor effects in vivo. PMID:22091632

Jeon, Yong Hyun; Lee, Ho Won; Lee, You La; Kim, Jung Eun; Hwang, Mi-Hye; Jeong, Shin Young; Lee, Sang-Woo; Ahn, Byeong-Cheol; Ha, Jeoung-Hee; Lee, Jaetae

2011-11-17

153

Human sodium iodide symporter added to multidrug resistance 1 small hairpin RNA in a single gene construct enhances the therapeutic effects of radioiodine in a nude mouse model of multidrug resistant colon cancer.  

PubMed

The objective of this study was to investigate the therapeutic potential of ¹³¹I added to doxorubicin therapy in multidrug resistance (MDR) mouse colon cancer coexpressing the MDR1 small hairpin RNA (shRNA) and human sodium iodide symporter (hNIS) gene in a single gene construct and to visualize the antitumor effects using molecular nuclear imaging. HCT-15 coexpressing shRNA for MDR1 gene (MDR1 shRNA) and hNIS gene with a single construct was established (referred to as MN61 cell). Inhibition of P-gp function by MDR1 shRNA and functional activity of hNIS gene was assessed using a ??(m)Tc sestamibi uptake and ¹²?I uptake, respectively. Cytotoxic effects by a combination of doxorubicin and ¹³¹I were determined in parental (HCT-15) or MN61 cells using an in vitro clonogenic assay. Therapeutic effect of either combination therapy (doxorubicin and ¹³¹I) or single therapy (doxorubicin or ¹³¹I alone) was evaluated by tumor volume measurement. ??(m)Tc-sestamibi, ¹²³I, and ??(m)Tc-pertechnetate images of mice were acquired to evaluate functional assessment in vivo. Cellular uptake of ??(m)Tc-sestamibi and ¹²?I was approximately 2-fold and 100-fold higher in MN61 cells than in parental cells, respectively. Combination of ¹³¹I and doxorubicin resulted in higher cytotoxcity in MN61 cells as compared with parental cells. Scintigraphic imaging showed higher uptake of ??(m)Tc-sestamibi and ¹²³I in MN61 tumor as compared with parental tumor. In mice treated with doxorubicin, there was a slight delay in tumor growth in the MN61 tumor but not in the parental tumor. Cancer treatment with ¹³¹I or doxorubicin induced a rapid reduction of tumor volume in the MN61 tumor but not in the parental tumor. Combination therapy further generated a rapid reduction of tumor volume as compared with ¹³¹I therapy alone (p?

Jeon, Yong Hyun; Ahn, Sohn Joo; Lee, Yong Jin; Lee, You La; Lee, Sang-Woo; Park, Seung-Yoon; Kim, In-San; Ahn, Byeong-Cheol; Ha, Jeoung-Hee; Lee, Jaetae

2010-12-01

154

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

SciTech Connect

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

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

1986-08-01

155

Characterization of a Pseudomonas putida ABC transporter (AatJMQP) required for acidic amino acid uptake: biochemical properties and regulation by the Aau two-component system.  

PubMed

We describe an ATP-binding cassette (ABC) transporter in Pseudomonas putida KT2440 that mediates the uptake of glutamate and aspartate. The system (AatJMQP, for acidic amino acid transport) is encoded by an operon involving genes PP1071-PP1068. A deletion mutant with inactivated solute-binding protein (KTaatJ) failed to grow on Glu and Gln as sole sources of carbon and nitrogen, while a mutant lacking a functional nucleotide-binding domain (KTaatP) was able to adapt to growth on Glu after an extended lag phase. Uptake of Glu and Asp by either mutant was greatly impaired at both low and high amino acid concentrations. The purified solute-binding protein AatJ exhibited high affinity towards Glu and Asp (K(d)=0.4 and 1.3 muM, respectively), while Gln and Asn as well as dicarboxylates (succinate and fumarate) were bound with much lower affinity. We further show that the expression of AatJMQP is controlled by the sigma(54)-dependent two-component system AauRS. Binding of the response regulator AauR to the aat promoter was examined by gel mobility shift assays and DNase I footprinting. By in silico screening, the AauR-binding motif (the inverted repeat TTCGGNNNNCCGAA) was detected in further P. putida KT2440 genes with established or putative functions in acidic amino acid utilization, and also occurred in other pseudomonads. The products of these AauR-responsive genes include the H(+)/Glu symporter GltP, a periplasmic glutaminase/asparaginase, AnsB, and phosphoenolpyruvate synthase (PpsA), a key enzyme of gluconeogenesis in Gram-negative bacteria. Based on these findings, we propose that AauR is a central regulator of acidic amino acid uptake and metabolism in pseudomonads. PMID:18310026

Singh, Birendra; Röhm, Klaus-Heinrich

2008-03-01

156

Changes in secondary structures and acidic side chains of melibiose permease upon cosubstrates binding.  

PubMed

Infrared difference spectroscopy analysis of the purified melibiose permease of Escherichia coli reconstituted into liposomes was carried out as a function of the presence of the two symporter substrates (Na(+), melibiose) in either H(2)O or in D(2)O media. Essentially, the data first show that addition of Na(+) induces appearance of peaks assigned to changes in the environment and/or orientation of alpha-helical domains of purified melibiose permease. Likewise, melibiose addition in the presence of Na(+) produces peaks corresponding to additional changes of alpha-helix environment or tilt. In addition to these changes, a pair of peaks (1599 (+) cm(-1)/1576 (-) cm(-1)) appearing in the Na(+)-induced difference spectrum is assigned to the antisymmetric stretching of COO(-) groups, since they show practically no shift upon H/D exchange. It is proposed that these acidic groups participate in Na(+) co-ordination. A corresponding pair of peaks, again fairly insensitive to H/D substitution (1591 (-) cm(-1)/1567 (+) cm(-1)), appear in the melibiose-induced difference spectra, and may again be assigned to COO(-) groups. The latter carboxyl groups may correspond to part or all of the acidic residues interacting with Lys or Arg in the resting state that become free upon melibiose binding. PMID:17012318

León, Xavier; Lemonnier, Raymonde; Leblanc, Gérard; Padrós, Esteve

2006-09-29

157

?pH-Dependent Amino Acid Transport into Plasma Membrane Vesicles Isolated from Sugar Beet (Beta vulgaris L.) Leaves  

PubMed Central

Proton-coupled aliphatic, neutral amino acid transport was investigated in plasma membrane vesicles isolated from sugar beet (Beta vulgaris L., cv Great Western) leaves. Two neutral amino acid symport systems were resolved based on inter-amino acid transport competition and on large variations in the specific activity of each porter in different species. Competitive inhibition was observed for transport competition between alanine, methionine, glutamine, and leucine (the alanine group) and between isoleucine, valine, and threonine (the isoleucine group). The apparent Km and Ki values were similar for transport competition among amino acids within the alanine group. In contrast, the kinetics of transport competition between these two groups of amino acids did not fit a simple competitive model. Furthermore, members of the isoleucine group were weak transport antagonists of the alanine group. These results are consistent with two independent neutral amino acid porters. In support of that conclusion, the ratio of the specific activity of alanine transport versus isoleucine transport varied from two- to 13-fold in plasma membrane vesicles isolated from different plant species. This ratio would be expected to remain relatively stable if these amino acids were moving through a single transport system and, indeed, the ratio of alanine to glutamine transport varied less than twofold. Analysis of the predicted structure of the aliphatic, neutral amino acids in solution shows that isoleucine, valine, and threonine contain a branched methyl or hydroxyl group at the ?-carbon position that places a dense electron cloud close to the ?-amino group. This does not occur for the unbranched amino acids or those that branch further away, e.g. leucine. We hypothesize that this structural feature of isoleucine, valine, and threonine results in unfavorable steric interactions with the alanine transport system that limits their flux through this porter. Hydrophobicity and hydrated volumes did not account for the observed differences in transport specificity.

Li, Zhen-Chang; Bush, Daniel R.

1991-01-01

158

[Recombinant Escherichia coli strains deficient in mixed acid fermentation pathways and capable of rapid aerobic growth on glucose with a reduced Crabtree effect].  

PubMed

In this study, we constructed and characterized Escherichia coli strains deficient for mixed acid fermentation pathways, which are capable of rapid aerobic growth on glucose without pronounced bacterial Crabtree effect. The main pathways of production of acetic and lactic acids and ethanol in these strains were inactivated by a deletion of the ackA, pta, poxB, IdhA, and adhEgenes. The phosphoenolpyruvate-dependent phosphotransferase system of glucose transport and phosphorylation was inactivated in the strains by a deletion of the ptsG gene. The possibility of alternative transport and phosphorylation of the carbohydrate substrate was ensured in recombinants by constitutive expression of the galP and glk genes, which encode the low-affinity H+-symporter of D-galactose and glucokinase, respectively. SGMI.0DeltaptsG PtacgalP and SG M1.0DeltaptsG PIglk PtacgalP strains were capable of rapid aerobic growth in a minimal medium containing 2.0 and 10.0 g/l of glucose and secreted only small amounts of acetic acid and trace amounts of pyruvic acid. PMID:23795471

Morzhakova, A A; Skorokhodova, A Iu; Gulevich, A Iu; Debabov, V G

159

Sequencing, bioinformatic characterization and expression pattern of a putative amino acid transporter from the parasitic cestode Echinococcus granulosus.  

PubMed

We have sequenced and partially characterized an Echinococcus granulosus cDNA, termed egat1, from a protoscolex signal sequence trap (SST) cDNA library. The isolated 1627 bp long cDNA contains an ORF of 489 amino acids and shows an amino acid identity of 30% with neutral and excitatory amino acid transporters members of the Dicarboxylate/Amino Acid Na+ and/or H+ Cation Symporter family (DAACS) (TC 2.A.23). Additional bioinformatics analysis of EgAT1, confirmed the results obtained by similarity searches and showed the presence of 9 to 10 transmembrane domains, consensus sequences for N-glycosylation between the third and fourth transmembrane domain, a highly similar hydropathy profile with ASCT1 (a known member of DAACS family), high score with SDF (Sodium Dicarboxilate Family) and similar motifs with EDTRANSPORT, a fingerprint of excitatory amino acid transporters. The localization of the putative amino acid transporter was analyzed by in situ hybridization and immunofluorescence in protoscoleces and associated germinal layer. The in situ hybridization labelling indicates the distribution of egat1 mRNA throughout the tegument. EgAT1 protein, which showed in Western blots a molecular mass of approximately 60 kD, is localized in the subtegumental region of the metacestode, particularly around suckers and rostellum of protoscoleces and layers from brood capsules. The sequence and expression analyses of EgAT1 pave the way for functional analysis of amino acids transporters of E. granulosus and its evaluation as new drug targets against cystic echinococcosis. PMID:18272295

Camicia, Federico; Paredes, Rodolfo; Chalar, Cora; Galanti, Norbel; Kamenetzky, Laura; Gutierrez, Ariana; Rosenzvit, Mara C

2008-02-12

160

Mycophenolic Acid  

Center for Drug Evaluation (CDER)

... Publications on Genomics. -. Mycophenolic Acid. Pharmacogenomic Information. ... Mycophenolic Acid, Transplantation, HGPRT, Precautions. ... More results from www.fda.gov/drugs/scienceresearch/researchareas

161

Mechanism of Fatty-Acid-Dependent UCP1 Uncoupling in Brown Fat Mitochondria  

PubMed Central

Mitochondrial uncoupling protein 1 (UCP1) is responsible for nonshivering thermogenesis in brown adipose tissue (BAT). Upon activation by long-chain fatty acids (LCFAs), UCP1 increases the conductance of the inner mitochondrial membrane (IMM) to make BAT mitochondria generate heat rather than ATP. Despite being a member of the family of mitochondrial anion carriers (SLC25), UCP1 is believed to transport H+ by an unusual mechanism that has long remained unresolved. Here, we achieved direct patch-clamp measurements of UCP1 currents from the IMM of BAT mitochondria. We show that UCP1 is an LCFA anion/H+ symporter. However, the LCFA anions cannot dissociate from UCP1 due to hydrophobic interactions established by their hydrophobic tails, and UCP1 effectively operates as an H+ carrier activated by LCFA. A similar LCFA-dependent mechanism of transmembrane H+ transport may be employed by other SLC25 members and be responsible for mitochondrial uncoupling and regulation of metabolic efficiency in various tissues.

Fedorenko, Andriy; Lishko, Polina V.

2013-01-01

162

Amino acid transport by membrane vesicles of an obligate anaerobic bacterium, Clostridium acetobutylicum.  

PubMed Central

Membrane vesicles were isolated from the obligate anaerobic bacterium Clostridium acetobutylicum. Beef heart mitochondrial cytochrome c oxidase was inserted in these membrane vesicles by membrane fusion by using the freeze-thaw sonication technique (A. J. M. Driessen, W. de Vrij, and W. N. Konings, Proc. Natl. Acad. Sci. USA 82:7555-7559, 1985) to accommodate them with a functional proton motive force-generating system. With ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine-cytochrome c as the electron donor, a proton motive force (delta p) of -80 to -120 mV was generated in these fused membranes. This delta p drove the accumulation of leucine and lysine up to 40- and 100-fold, respectively. High transport activities were observed in fused membranes containing Escherichia coli lipids, whereas the transport activities in fused membranes containing mainly soybean lipids or phosphatidylcholine were low. It is suggested that branched-chain amino acids and lysine were taken up by separate systems. The effects of the ionophores nigericin and valinomycin indicated that lysine and leucine were translocated in symport with a proton.

Driessen, A J; Ubbink-Kok, T; Konings, W N

1988-01-01

163

Acid rain  

Microsoft Academic Search

Acid precipitation is a global problem. The effects were first seen in Europe; it affects the Great Lakes and the Midwest because higher-than-normal levels of acidity in rain are found in these areas. Several bays of the Great Lakes are now known to receive substantial runoff from freshwater streams that have been made acidic by acid rains. These areas may

1979-01-01

164

Acid rain  

SciTech Connect

A series of definitions for the field of acid rain studies are presented. Protocols for acid rain sampling and monitoring are also presented. A procedure for calculatory precipitation pH is discussed. 11 references, 1 table.

Stensland, G.J.

1983-11-01

165

Oleanolic acid.  

PubMed

Oleanolic acid (3?-hydroxyolean-12-en-28-oic acid) is a pentacyclic triterpenoid compound with a widespread occurrence throughout the plant kingdom. In nature, the compound exists either as a free acid or as an aglycone precursor for triterpenoid saponins, in which it can be linked to one or more sugar chains. Oleanolic acid and its derivatives possess several promising pharmacological activities, such as hepatoprotective effects, and anti-inflammatory, antioxidant, or anticancer activities. With the recent elucidation of its biosynthesis and the imminent commercialization of the first oleanolic acid-derived drug, the compound promises to remain important for various studies. In this review, the recent progress in understanding the oleanolic acid biosynthesis and its pharmacology are discussed. Furthermore, the importance and potential application of synthetic oleanolic acid derivatives are highlighted, and research perspectives on oleanolic acid are given. PMID:22377690

Pollier, Jacob; Goossens, Alain

2012-02-28

166

Aminocaproic Acid  

MedlinePLUS

Aminocaproic acid is used to control bleeding that occurs when blood clots are broken down too quickly. This type ... the baby is ready to be born). Aminocaproic acid is also used to control bleeding in the ...

167

Ethacrynic Acid  

MedlinePLUS

Ethacrynic acid, a 'water pill,' is used to treat swelling and fluid retention caused by various medical problems. It ... Ethacrynic acid comes as a tablet to take by mouth. It is usually taken once or twice a day ...

168

Acid Reflux  

MedlinePLUS

... end of the esophagus called the lower esophageal sphincter or “LES” — keeps the acid in the stomach ... moderately symptomatic GERD. These drugs increase lower esophageal sphincter pressure, which helps prevent acid reflux, and improves ...

169

Acidizing method  

SciTech Connect

A method is described for acidizing a subterranean formation, comprising the steps of: (a) forming an acidizing composition by mixing an aqueous acid component with at least one water-soluble organosilicon compound; and (b) injecting the composition into the formation.

Watkins, D.R.; Kalfayan, L.J.; Hewgill, G.S.

1987-03-03

170

The Proton Electrochemical Transmembrane Gradients Generated by the Transfer Cells of the Haustorium of Polytrichum formosum and Their Use in the Uptake of Amino Acids  

PubMed Central

The epidermal cells of the sporophyte haustorium of Polytrichum formosum are modified into transfer cells. These cells are located in a strategic place allowing them to control the exchanges between the two generations. Their plasmalemma creates proton gradients (?? and ?pH) which increase during the development of the sporophyte. As the sporophyte grows from 2 to 4 cm long, the pH of the incubation medium of the haustoria decreases from 5.2 to 4.3, and the transmembrane potential difference (PD) hyperpolarizes form ?140 to ?210 millivolts. These gradients become rapidly larger than that generated by the plasmalemma of the basal cells of the sporophyte. They are used to energize the uptake of the solutes present in the apoplast of the gametophyte, particularly the amino acids. Below 20 micromolar ?-aminoisobutyric acid uptake in the transfer cells is mediated by a saturable system and is optimal at acidic pH (4.0 and 4.5). It is strongly inhibited by compounds dissipating both ?? and ?pH (10 micromolar carbonylcyanide-m-chlorophenyl hydrazone) or only ?? (0.1 molar KCl). The absorption of ?-aminoisobutyric acid and of the other neutral amino acids tested induces an alkalinization of the medium and a depolarization of membrane potential difference which is concentration dependent. These data show that the uptake of amino acids by the transfer cells of the haustorium is a secondary translocation (proton-amino acid symport) energized by a primary translocation (proton efflux). More particularly, they show that transfer cells possess a membrane enzymic equipment particularly efficient to achieve the uptake of the solutes leaked in the apoplast from other cell types.

Renault, Sylvie; Despeghel-Caussin, Chantal; Bonnemain, Jean-Louis; Delrot, Serge

1989-01-01

171

NHEVNAT: an H+ V-ATPase electrically coupled to a Na+:nutrient amino acid transporter (NAT) forms an Na+/H+ exchanger (NHE)  

PubMed Central

Summary Glycolysis, the citric acid cycle and other metabolic pathways of living organisms generate potentially toxic acids within all cells. One ubiquitous mechanism for ridding cells of the acids is to expel H+ in exchange for extracellular Na+, mediated by electroneutral transporters called Na+/H+ exchangers (NHEs) that are driven by Na+ concentration gradients. The exchange must be important because the human genome contains 10 NHEs along with two Na+/H+ antiporters (NHAs). By contrast, the genomes of two principal disease vector mosquitoes, Anopheles gambiae and Aedes aegypti, contain only three NHEs along with the two NHAs. This shortfall may be explained by the presence of seven nutrient amino acid transporters (NATs) in the mosquito genomes. NATs transport Na+ stoichiometrically linked to an amino acid into the cells by a process called symport or co-transport. Three of the mosquito NATs and two caterpillar NATs have previously been investigated after heterologous expression in Xenopus laevis oocytes and were found to be voltage driven (electrophoretic). Moreover, the NATs are present in the same membrane as the H+ V-ATPase, which generates membrane potentials as high as 120 mV. We review evidence that the H+ V-ATPase moves H+ out of the cells and the resulting membrane potential (Vm) drives Na+ linked to an amino acid into the cells via a NAT. The H+ efflux by the V-ATPase and Na+ influx by the NAT comprise the same ion exchange as that mediated by an NHE; so the V and NAT working together constitute an NHE that we call NHEVNAT. As the H+ V-ATPase is widely distributed in mosquito epithelial cells and there are seven NATs in the mosquito genomes, there are potentially seven NHEVNATs that could replace the missing NHEs. We review published evidence in support of this hypothesis and speculate about broader functions of NHEVNATs.

Harvey, William R.; Boudko, Dmitri Y.; Rheault, Mark R.; Okech, Bernard A.

2009-01-01

172

Basically Acids  

NSDL National Science Digital Library

Students learn the basics of acid/base chemistry in a fun, interactive way by studying instances of acid/base chemistry found in popular films such as Harry Potter and the Prisoner of Azkaban and National Treasure. Students learn what acids, bases and indicators are and how they can be used, including invisible ink. They also learn how engineers use acids and bases every day to better our quality of life. Students' interest is piqued by the use of popular culture in the classroom.

University Of Houston

173

Mefenamic Acid  

MedlinePLUS

... any of the following symptoms, stop taking mefenamic acid and call your doctor: stomach pain, heartburn, vomit that is bloody or looks ... Mefenamic acid may cause side effects. Tell your doctor if any of these ... nervousness ringing in the ears Some side effects can be serious. If you ...

174

Acid test  

NSDL National Science Digital Library

Baking soda can be used as an indicator of how much acid a substance contains. Lemons and limes have more acid in them than grapefruits and oranges. Indophenol can be used as an indicator of how much vitamin C is in a substance.

Olivia Worland (Purdue University;Biological Sciences)

2008-06-06

175

Acid Rain  

Microsoft Academic Search

Measurements of the acidity of rain and snow reveal that in parts of the eastern U.S. and of western Europe precipitation has changed from a nearly neutral solution 200 years ago to a dilute solution of sulfuric and nitric acids today. The trend is a result of the emission of sulfur and nitrogen oxides to the atmosphere accompanying the rise

Gene E. Likens; Richard F. Wright; James N. Galloway; Thomas J. Butler

1979-01-01

176

Acid rain  

SciTech Connect

This book was written in a concise and readable style for the lay public. It's purpose was to make the public aware of the damage caused by acid rain and to mobilize public opinion to favor the elimination of the causes of acid rain.

Elsworth, S.

1985-01-01

177

Acid rain  

SciTech Connect

This book presents the proceedings of the third annual conference sponsored by the Acid Rain Information Clearinghouse (ARIC). Topics covered include: Legal aspects of the source-receptor relationship: an energy perspective; Scientific uncertainty, agency inaction, and the courts; and Acid rain: the emerging legal framework.

White, J.C. (Cornell University, Ithaca, NY (US))

1988-01-01

178

Hydrochloric acid  

Microsoft Academic Search

The effect of a single instillation of acid and pepsin on the cell proliferation in the distal esophageal mucosa was investigated in four dogs. The doses of acid and pepsin used were lower than those provoking acute esophagitis and erosions. Usingin vitro labeling with [3H]thymidine and autoradiography, the epithelial mitotic and DNA synthesis indices were determined at 0, 4, 8,

A. De Backer; P. Haentjens; G. Willems

1985-01-01

179

Acids (GCMP)  

NSDL National Science Digital Library

Acids: this is a resource in the collection "General Chemistry Multimedia Problems". We will observe the reaction of sodium bicarbonate with three acid solutions. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

180

Domoic Acid  

NSDL National Science Digital Library

This online student report discusses the chemistry of domoic acid, a biotoxin that is produced by the diatom Psuedo-nitzschia and associated with Amnesiac Shellfish Poisoning (ASP). In addition to a descriptive summary and images, the report links to other areas of interest related to domoic acid poisoning including signs and symptoms, modes of action, and treatment.

Kohlen, Corinne; Bailey, Christina

2010-02-10

181

Acid Precipitation  

NSDL National Science Digital Library

Acid precipitation will be defined. At different points in the lesson students will write balanced reactions for the formation acid precipitation from atmospheric sulfur and nitrogen oxides and the neutralization of acids by limestone. Students will determine which states are most at risk from acid precipitation and assess how that risk has changed from 1996 to 2006. Sources of atmospheric sulfur (burning of high-sulfur coal) and nitrogen oxides (automobile exhaust) will be listed. The buffering effect of limestone soils and its mitigating effect on acid precipitation will be discussed. Students will correlate these areas with sulfur and nitrogen oxide production, population, composition of coal fields, and soil composition. This resource includes both a teaching guide and student worksheets.

Tyser, Jim

2011-09-15

182

Acid rain  

SciTech Connect

Acid precipitation has become one of the major environmental problems of this decade. It is a challenge to scientists throughout the world. Researchers from such diverse disciplines as plant pathology, soil science, bacteriology, meteorology and engineering are investigating different aspects of acid precipitation. Despite some unknowns, the preponderance of our evidence to date points to the need to control the emissions of acid-forming sulfur and nitrogen compounds. Given the potential for damage from acid precipitation, prudence dictates that we act soon to avoid far more serious problems in the future. EPA's regulatory standards for new power plants and motor vehicles are a major step in the right direction. Further steps may be required in the near future. This background document tells what we know - and don't know - about acid precipitation.

Not Available

1980-07-01

183

Acid Rain  

NSDL National Science Digital Library

Due to the presence of dissolved gases such as carbon dioxide, rainfall is naturally acidic. The release of other gases and chemicals such as sulfur dioxide during the combustion of coal and oil can cause rainfall to become even more acidic, sometimes to the point of toxicity. In this activity, students will measure the pH of local rainfall to see what effect these gases have in their region. They will also check an online resource to see how the releases of acid rain-causing chemicals have varied over the past 20 years, and answer questions about the information they uncover.

Fox, Chris

184

Tranexamic Acid  

MedlinePLUS

... or lower legs hoarseness changes in vision, including color vision chest pain shortness of breath leg pain, swelling, tenderness, redness, or warmth Tranexamic acid may cause other side effects. Call your doctor if you have any unusual ...

185

Valproic Acid  

MedlinePLUS

... with other medications to treat certain types of seizures. Valproic acid is also used to treat mania ( ... a severe, long-lasting and possibly life-threatening seizure. Your doctor will probably decrease your dose gradually.

186

?-Amino acids  

Microsoft Academic Search

Summary 1.It has been established that by the decarboxylation of the glycidic acid, obtained by Darzens' method from cis-decahydro-2-naphthol of m.p. 105°, a mixture of stereoisomeric decahydro-2-naphthaldehydes is formed; these have not been investigated further.2.The synthesis has been affected, by Rodionov's method, of ß-(2-decalyl)-ß-alanine (ß-aminodecahydro-2-naphthalenepropionic acid), which also appeared to be a mixture of isomers, the separation of which was

V. M. Rodionov; L. V. Antik

1953-01-01

187

Acidizing with chemically heated weak acid  

SciTech Connect

Materials in and around a well are acidized with chemically heated, hot acid by injecting a solution of both nitrogen and heat generating reactants and a mixture of weak acid and weak acid salt that both buffers the relation and provides a weak acid acidizing solution.

Richardson, E. A.

1984-11-13

188

Stearic Acid  

ERIC Educational Resources Information Center

|A chemical laboratory information profile (CLIP) is presented for the chemical, stearic acid. The profile lists the chemical's physical and harmful characteristics, exposure limits, and symptoms of major exposure, for the benefit of teachers and students, who use the chemical in the laboratory.|

Young, Jay A.

2004-01-01

189

Acid rain  

SciTech Connect

An overview is presented of acid rain and the problems it causes to the environment worldwide. The acidification of lakes and streams is having a dramatic effect on aquatic life. Aluminum, present in virtually all forest soils, leaches out readily under acid conditions and interferes with the gills of all fish, some more seriously than others. There is evidence of major damage to forests in European countries. In the US, the most severe forest damage appears to be in New England, New York's Adirondacks, and the central Appalachians. This small region is part of a larger area of the Northeast and Canada that appears to have more acid rainfall than the rest of the country. It is downwind from major coal burning states, which produce about one quarter of US SO/sub 2/ emissions and one sixth of nitrogen oxide emissions. Uncertainties exist over the causes of forest damage and more research is needed before advocating expensive programs to reduce rain acidity. The President's current budget seeks an expansion of research funds from the current $30 million per year to $120 million.

Not Available

1984-06-01

190

Carbonate acidizing  

SciTech Connect

The authors present the first quantitative study and complete model of the wormholing phenomenon, leading to a means of predicting and optimizing carbonate acidizing treatments. Laboratory experiments on a gypsum model system and computer simulations show that for a given geometry, wormholes can be quantified by a unique parameter, their equivalent hydraulic length. The behavior of this quantifying parameter vs. all the system parameters is studied and allows the quantitative prediction of the efficiency of an acidizing treatment. This study highlights the fractal nature of the phenomenon, which is accounted for in the equations, and the strong effect of the sample geometry. Three types of etching can be obtained: compact, wormhole type, or homogeneous. The optimum conditions for achieving the best skin decrease correspond to the creation of wormholes and can then be defined in terms of fluid reactivity and injection rate.

Daccord, G.; Touboul, E.; Lenormand, R.

1989-02-01

191

Acidizing sandstone formations with fluoboric acid  

SciTech Connect

The continuing search for an effective deep-penetrating sandstone acidizing system recently has focused on fluoboric acid (HBF/sub 4/). Because this acid first must hydrolyze in water to produce HF, it was believed that deeper radial penetration of live acid could be achieved during matrix acidizing operations. However, a thorough experimental study has shown that typical formation temperatures will cause fluoboric acid to spend at a rapid rate similar to that of conventional hydrofluoric acid (HF), thereby severly limiting its usefulness in most sandstone formations. Furthermore, the same silica reprecipitation potential associated with HF acidizing is also inherent in the HBF/sub 4/ system.

Kunze, K.R.; Shaughnessy, C.M.

1983-02-01

192

Sodium-dependent transport of neutral amino acids by whole cells and membrane vesicles of Streptococcus bovis, a ruminal bacterium.  

PubMed Central

Streptococcus bovis JB1 cells were able to transport serine, threonine, or alanine, but only when they were incubated in sodium buffers. If glucose-energized cells were washed in potassium phosphate and suspended in potassium phosphate buffer, there was no detectable uptake. Cells deenergized with 2-deoxyglucose and incubated in sodium phosphate buffer were still able to transport serine, and this result indicated that the chemical sodium gradient was capable of driving transport. However, when the deenergized cells were treated with valinomycin and diluted into sodium phosphate to create both an artificial membrane potential and a chemical sodium gradient, rates of serine uptake were fivefold greater than in cells having only a sodium gradient. If deenergized cells were preloaded with sodium (no membrane potential or sodium gradient), there was little serine transport. Nigericin and monensin, ionophores capable of reversing sodium gradients across membranes, strongly inhibited sodium-dependent uptake of the three amino acids. Membrane vesicles loaded with potassium and diluted into either lithium or choline chloride were unable to transport serine, but rapid uptake was evident if sodium chloride was added to the assay mixture. Serine transport had an extremely poor affinity for sodium, and more than 30 mM was needed for half-maximal rates of uptake. Serine transport was inhibited by an excess of threonine, but an excess of alanine had little effect. Results indicated that S. bovis had separate sodium symport systems for serine or threonine and alanine, and either the membrane potential or chemical sodium gradient could drive uptake.

Russell, J B; Strobel, H J; Driessen, A J; Konings, W N

1988-01-01

193

Understanding Acid Rain  

ERIC Educational Resources Information Center

|The term acid rain describes rain, snow, or fog that is more acidic than normal precipitation. To understand what acid rain is, it is first necessary to know what an acid is. Acids can be defined as substances that produce hydrogen ions (H+), when dissolved in water. Scientists indicate how acidic a substance is by a set of numbers called the pH…

Damonte, Kathleen

2004-01-01

194

Acidizing concepts - Matrix vs. fracture acidizing  

SciTech Connect

Acidizing involves a wide range of stimulation treatments that can yield impressive production increases in many wells if properly applied. Acidizing treatments are divided into two categories: matrix acidizing and fracture acidizing. To use either treatment properly, an understanding is required of what the treatments do and what is necessary to stimulate the well.

King, G.E.

1986-05-01

195

Improvement of ethanol production from D-lactic acid by constitutive expression of lactate transporter Jen1p in Saccharomyces cerevisiae.  

PubMed

To improve ethanol production from D-lactate, Jen1p, a monocarboxylate-proton symporter, was constitutively expressed in Saccharomyces cerevisiae NAM34-4C. The mutant produced 2.4 g/L of ethanol, approximately 2.4 times higher than that of the wild-type strain. A monocarboxylate/proton symporter gene (JEN1) null mutant was also constructed. It produced 0.19 g/L of ethanol, 5 times lower than that of the wild-type strain. PMID:23649240

Wakamatsu, Makoto; Tomitaka, Masataka; Tani, Tatsunori; Taguchi, Hisataka; Kida, Kenji; Akamatsu, Takashi

2013-05-07

196

New method of acidizing or acid fracturing: crosslinked acid gels  

SciTech Connect

Acid polymer gels having pH less than one have been crosslinked for retarding the chemical and physical activity of hydrochloric acid on calcareous formations. Hydrochloric acid concentrations from .0025 to 28% have been successfully crosslinked. This stimulation fluid offers high viscosity with adequate shear stability, perfect support for proppants, and clay stabilization. Additionally, the fluid provides effective fluid loss control and retardation of acid reaction enabling live acid to penetrate deeper into the formation for better formation conductivity and practically a residue-free break for rapid clean-up of the well after the job. Results of lab and field tests show the acid crosslinked system to be an effective stimulation fluid for acidizing and acid fracturing in calcareous and sandstone formations having low formation permeability.

Pabley, A.S.; Holcomb, D.L.

1980-01-01

197

Acid rain  

SciTech Connect

Deposition of acidic substances from the atmosphere is considered by many to be, along with increasing CO/sub 2/ concentrations in the atmosphere, one of the most serious environmental problems of this generation. Despite the limited title of this small book, it touches, in a nontechnical and elementary way, on all of the important aspects of this subject: definitions, history, suspected causes and harmful effects, proposed remedial actions, the case for additional research, and political and economic impacts. The material is presented largely as statements and opinions of scientists and governmental officials. The book is reportorial in style and reasonably balanced in its presentation of contrasting and opposing opinions about causes, effects, and remedies, although the final chapter, What Citizens Can Do, includes the names and addresses of organizations involved in efforts to protect clean air, forestry and wilderness areas. Also included are school projects and examples of what individuals and groups have done to help us understand the problem and/or to promote action.

Gay, K.

1983-01-01

198

Uric acid test (image)  

MedlinePLUS

Uric acid urine test is performed to check for the amount of uric acid in urine. Urine is collected over a 24 ... testing. The most common reason for measuring uric acid levels is in the diagnosis or treatment of ...

199

Bioavailability of phenolic acids  

Microsoft Academic Search

Two large classes of phenolic acids were comprised in this review: benzoic acid derivatives and cinnamic acid derivatives.\\u000a They have been found to be very extended in fruits and vegetables at different concentrations. For example, hydroxycinnamic\\u000a acids concentration was higher than that found for hydroxybenzoic acids. Concerning their consumption, hydroxycinnamic acids\\u000a provide larger contributions to the total polyphenol intake than

Sophie Lafay; Angel Gil-Izquierdo

2008-01-01

200

BBB - Domoic Acid Structure  

Center for Food Safety and Applied Nutrition (CFSAN)

... BBB - Domoic Acid Structure. Bad Bug Book: Foodborne Pathogenic Microorganisms and Natural Toxins Handbook Domoic Acid. ... More results from www.fda.gov/food/foodborneillnesscontaminants/causesofillnessbadbugbook

201

BBB - Okadaic Acid Structure  

Center for Food Safety and Applied Nutrition (CFSAN)

... BBB - Okadaic Acid Structure. Bad Bug Book: Foodborne Pathogenic Microorganisms and Natural Toxins Handbook Okadaic Acid. ... More results from www.fda.gov/food/foodborneillnesscontaminants/causesofillnessbadbugbook

202

Refining Lurgi tar acids  

Microsoft Academic Search

There is disclosed a process for removing tar bases and neutral oils from the Lurgi tar acids by treating the tar acids with aqueous sodium bisulfate to change the tar bases to salts and to hydrolyze the neutral oils to hydrolysis products and distilling the tar acids to obtain refined tar acid as the distillate while the tar base salts

Greco

1984-01-01

203

Acid-Base Equilibria  

NSDL National Science Digital Library

This 9-page PDF document is part of an environmental geochemistry course taught by Dr. David Sherman at the University of Bristol. Topics include acid-base theories, aqueous systems, strong and weak acids and bases, acid-base properties of minerals, the pH of weak acid and buffered systems, and the calculation of titration curves.

Sherman, David W.; Bristol, University O.

204

21 CFR 172.860 - Fatty acids.  

Code of Federal Regulations, 2013 CFR

...acids and their associated fatty acids manufactured from fats and oils derived from edible sources: Capric acid, caprylic acid, lauric acid, myristic acid, oleic acid, palmitic acid, and stearic acid. (b) The food additive meets the...

2013-04-01

205

21 CFR 172.860 - Fatty acids.  

Code of Federal Regulations, 2010 CFR

...acids and their associated fatty acids manufactured from fats and oils derived from edible sources: Capric acid, caprylic acid, lauric acid, myristic acid, oleic acid, palmitic acid, and stearic acid. (b) The food additive meets the...

2009-04-01

206

21 CFR 172.860 - Fatty acids.  

Code of Federal Regulations, 2010 CFR

...acids and their associated fatty acids manufactured from fats and oils derived from edible sources: Capric acid, caprylic acid, lauric acid, myristic acid, oleic acid, palmitic acid, and stearic acid. (b) The food additive meets the...

2010-01-01

207

Uric acid nephrolithiasis.  

PubMed

Uric acid nephrolithiasis may be the final manifestation of various pathophysiological processes. Recent advances in renal urate transport have elucidated mechanisms by which hyperuricosuria occurs. However, in most uric acid stone formers the primary pathophysiologic defect is an excessively acidic urine pH rather than hyperuricosuria. Insulin resistance may contribute to the development of acidic urine by augmenting endogenous acid production and decreasing renal ammonium excretion. Medical management strategies focus primarily on alkali treatment or decreasing hyperuricosuria. PMID:17678984

Cameron, Mary Ann; Sakhaee, Khashayar

2007-08-01

208

Acids and Bases (Netorials)  

NSDL National Science Digital Library

Acids and Bases: this is a resource in the collection "Netorials". In this module there is an introduction to the chemical properties of acids and bases. Afterwards, the sections include topics such as Molecular Structures of Acids and Bases, Ionization constants, properties of salts, buffers and Lewis theory of Acids and Bases. The Netorials cover selected topics in first-year chemistry including: Chemical Reactions, Stoichiometry, Thermodynamics, Intermolecular Forces, Acids & Bases, Biomolecules, and Electrochemistry.

209

Detection of bound phenolic acids: prevention by ascorbic acid and ethylenediaminetetraacetic acid of degradation of phenolic acids during alkaline hydrolysis  

Microsoft Academic Search

The experimental conditions commonly used to detect bound phenolic acids by alkaline hydrolysis result in loss of several phenolic acids, particularly dihydroxy-derivatives (caffeic acid, dihydrocaffeic acid, homogentisic acid). In this study we show that the addition of ascorbic acid, a strong antioxidant, and ethylenediaminetetraacetic acid, a metal chelator, totally prevent the loss of phenolic acids during alkaline hydrolysis. In these

M Nardini; E Cirillo; F Natella; D Mencarelli; A Comisso; C Scaccini

2002-01-01

210

Gas-phase Acidities of Aspartic Acid, Glutamic Acid, and their Amino Acid Amides.  

SciTech Connect

Gas-phase acidities (GA or ?Gacid) for the two most acidic common amino acids, aspartic acid and glutamic acid, have been determined for the first time. Because of the amide linkage’s importance in peptides and as an aid in studying side chain versus main chain deprotonation, aspartic acid amide and glutamic acid amide were also studied. Experimental GA values were measured by proton transfer reactions in an electrospray ionization/Fourier transform ion cyclotron resonance mass spectrometer. Calculated GAs were obtained by density functional and molecular orbital theory approaches. The best agreement with experiment was found at the G3MP2 level; the MP2/CBS and B3LYP/aug-cc-pVDZ results are 3–4 kcal/mol more acidic than the G3MP2 results. Experiment shows that aspartic acid is more acidic than glutamic acid by ca. 3 kcal/mol whereas the G3MP2 results show a smaller acidity difference of 0.2 kcal/mol. Similarly, aspartic acid amide is experimentally observed to be ca. 2 kcal/mol more acidic than glutamic acid amide whereas the G3MP2 results show a correspondingly smaller energy difference of 0.7 kcal/mol. The computational results clearly show that the anions are all ring-like structures with strong hydrogen bonds between the OH or NH2 groups and the CO2? group from which the proton is removed. The two amino acids are main-chain deprotonated. In addition, use of the COSMO model for the prediction of the free energy differences in aqueous solution gave values in excellent agreement with the most recent experimental values for pKa. Glutamic acid is predicted to be more acidic than aspartic acid in aqueous solution due to differential solvation effects.

Li, Zhong; Matus, Myrna H.; Velazquez, Hector A.; Dixon, David A.; Cassady, Carolyn J.

2007-02-14

211

OATP8/1B3-mediated cotransport of bile acids and glutathione: an export pathway for organic anions from hepatocytes?  

PubMed

In cholestasis, the accumulation of organic anions in hepatocytes is reduced by transporters (multidrug resistance-associated proteins and OSTalpha-OSTbeta) able to extrude them across the basolateral membrane. Here we investigated whether organic anion-transporting polypeptides (OATPs) may contribute to this function. Xenopus laevis oocytes expressing human carboxylesterase-1 efficiently loaded cholic acid (CA) methyl ester, which was cleaved to CA and exported. Expression of OATP8/1B3 enhanced CA efflux, which was trans-activated by taurocholate but trans-inhibited by reduced (GSH) and oxidized (GSSG) glutathione. Moreover, taurocholate and estradiol 17beta-D-glucuronide, but not bicarbonate and glutamate, cis-inhibited OATP8/1B3-mediated bile acid transport, whereas glutathione cis-stimulated this process, which involved the transport of glutathione itself with a stoichiometry of 2:1 (GSH/bile acid). No cis-activation by glutathione of OATP-C/1B1 was found. Using real time quantitative reverse transcription-PCR, the absolute abundance of OATP-A/1A2, OATP-C/1B1, and OATP8/1B3 mRNA in human liver biopsies was measured. In healthy liver, expression levels of OATP-C/1B1 were approximately 5-fold those of OATP8/1B3 and >100-fold those of OATP-A/1A2. This situation was not substantially modified in several cholestatic liver diseases studied here. In conclusion, although both OATP-C/1B1 and OATP8/1B3 are highly expressed, and able to transport bile acids, their mechanisms of action are different. OATP-C/1B1 may be involved in uptake processes, whereas OATP8/1B3 may mediate the extrusion of organic anions by symporting with glutathione as a normal route of exporting metabolites produced by hepatocytes or preventing their intracellular accumulation when their vectorial traffic toward the bile is impaired. PMID:16877380

Briz, Oscar; Romero, Marta R; Martinez-Becerra, Pablo; Macias, Rocio I R; Perez, Maria J; Jimenez, Felipe; San Martin, Francisco G; Marin, Jose J G

2006-07-28

212

Acid Inhibition and the Acid Rebound Effect  

Microsoft Academic Search

Acid secretion from gastric parietal cells is a result of a complex interaction between different stimulatory and inhibitory mediators. One of the most important mediators is gastrin, which stimulates gastric acid secretion from parietal cells mostly indirectly, by the release of histamine from enterochromaffin-like (ECL) cells. Therapy with antisecretory agents leads to hypergastrinemia, mucosal hyperplasia and increased ECL cell mass,

Marko Duvnjak

2011-01-01

213

Acid Thunder: Acid Rain and Ancient Mesoamerica  

ERIC Educational Resources Information Center

|Much of Mesoamerica's rich cultural heritage is slowly eroding because of acid rain. Just as water dissolves an Alka-Seltzer tablet, acid rain erodes the limestone surfaces of Mexican archaeological sites at a rate of about one-half millimeter per century (Bravo et al. 2003). A half-millimeter may not seem like much, but at this pace, a few…

Kahl, Jonathan D. W.; Berg, Craig A.

2006-01-01

214

Purification of oleic acid and linoleic acid  

SciTech Connect

To permit kinetic studies of the reactivity of unsaturated fatty acids towards oxygen radicals, it is essential to remove traces of hydroperoxides and other conjugated lipid impurities commonly present in commercial samples. Removal of these impurities has been satisfactorily achieved for oleic and linoleic acids by anaerobic low temperature recrystallization from acetonitrile. The uv spectra of commercial and purified samples are compared.

Arudi, R.L.; Sutherland, M.W.; Bielski, B.H.J.

1983-01-01

215

New bioactive fatty acids.  

PubMed

Many oxygenated fatty acids are bioactive compounds. Nocardia cholesterolicum and Flavobacterium DS5 convert oleic acid to 10 hydroxy stearic acid and linoleic acid to 10-hydroxy-12(Z)-octadecanoic acid. Pseudomonas aeruginosa PR3 converts oleic acid to the new compounds, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) through 10-hydroxy-8-octadecenoic acid, and racinoleic acid to 7,10,12-trihydroxy-8-octadecenoic acid. DOD showed antibacterial activity including against food-borne pathogens. Bacillus megaterium ALA2 converted n-6 and n-3 PUFAs to many new oxygenated fatty acids. For example: linoleic acid was converted to12,13-epoxy-9-octadecenoic acid and then to 12,13-dihydroxy-9-octadecenoic acid (12,13-DHOA). From here, there are two bioconversion pathways. The major pathway is: 12,13-DHOA --> 12,13,17-trihydroxy-9(S)-octadecenoic acid (THOA) --> 12,17;13,17-diepoxy-16-hydroxy-9(Z)-octadecenoic acid (DEOA) --> 7-hydroxy-DEOA. The minor pathway is: 12,13-DHOA --> 12,13,16-THOA --> 12-hydroxy-13,16-epoxy-9(Z)-octadecenoic acid. 12,13,17-THOA has anti-plant pathogenic fungal activity. The tetrahydrofuranyl moiety is known in anti cancer drugs. Strain ALA2 also converts other n-3 and n-6 PUFAs such as eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) to many new oxygenated unsaturated fatty acid products. All of these new products have high potential for antimicrobial agents or biomedical applications. We also screened 12 Mortierella fungal strains from the ARS Culture Collection for the production of bioactive fatty acids such as dihomo-gama-linolenic acid (DGLA) and arachidonic acid. All of the strains tested produced AA and DGLA from glucose or glycerol. The top five AA producers (mg AA/g CDW) were in the following order: M. alpina > M. zychae > M. hygrophila > M. minutissima > M. parvispora. Both AA and DGLA are important natural precursors of a large family of prostaglandin and thromboxane groups. PMID:18296335

Hou, Ching T

2008-01-01

216

Zoledronic Acid Injection  

MedlinePLUS

... acid (Reclast) is used to prevent or treat osteoporosis (condition in which the bones become thin and ... Zoledronic acid (Reclast) is also used to treat osteoporosis in men, and to prevent or treat osteoporosis ...

217

Mixed Acid Oxidation  

SciTech Connect

Several non-thermal processes have been developed to destroy organic waste compounds using chemicals with high oxidation potentials. These efforts have focused on developing technologies that work at low temperatures, relative to incineration, to overcome many of the regulatory issues associated with obtaining permits for waste incinerators. One such technique with great flexibility is mixed acid oxidation. Mixed acid oxidation, developed at the Savannah River Site, uses a mixture of an oxidant (nitric acid) and a carrier acid (phosphoric acid). The carrier acid acts as a non-volatile holding medium for the somewhat volatile oxidant. The combination of acids allows appreciable amounts of the concentrated oxidant to remain in the carrier acid well above the oxidant''s normal boiling point.

Pierce, R.A.

1999-10-26

218

Hydrochloric acid poisoning  

MedlinePLUS

Hydrocholoric acid is a clear, poisonous liquid. It is highly corrosive, which means it immediately causes severe damage, such ... poisoning due to swallowing or breathing in hydrochloric acid. This is for information only and not for ...

219

Acid-fast stain  

MedlinePLUS

The acid-fast stain is a laboratory test that determines if a sample of tissue, blood, or other body ... lab team member washes the slide with an acid solution and applies a different stain. The bacteria ...

220

Carbolic acid poisoning  

MedlinePLUS

Phenol poisoning; Phenylic acid poisoning; Hydroxybenzene poisoning; Phenic acid poisoning; Benzenol poisoning ... Phenol ... and Disease Registry (ATSDR). 2008. Toxicological profile for Phenol. Atlanta, GA: U.S. Department of Health and Human ...

221

Lactic acid test  

MedlinePLUS

Lactate test ... test. Exercise can cause a temporary increase in lactic acid levels. ... oxygen. See: Oxygen deprivation Conditions that can increase lactic acid levels include: Heart failure Liver problems Lung disease ...

222

Aminocaproic Acid Injection  

MedlinePLUS

Aminocaproic acid injection is used to control bleeding that occurs when blood clots are broken down too quickly. This ... the baby is ready to be born). Aminocaproic acid injection is also used to control bleeding in ...

223

Polymerization of Itaconic Acid.  

National Technical Information Service (NTIS)

Itaconic acid has various uses in chain copolymerization reactions, because of its two carboxylic groups and relatively good reactivity with different comonomers. As an unsaturated dicarboxylic acid it also has applications in grafting reactions and polyc...

J. Ahlgren

1990-01-01

224

Acid inhibition and the acid rebound effect.  

PubMed

Acid secretion from gastric parietal cells is a result of a complex interaction between different stimulatory and inhibitory mediators. One of the most important mediators is gastrin, which stimulates gastric acid secretion from parietal cells mostly indirectly, by the release of histamine from enterochromaffin-like (ECL) cells. Therapy with antisecretory agents leads to hypergastrinemia, mucosal hyperplasia and increased ECL cell mass, which results in increase of gastric acid secretion capacity. This increased secretion capacity has been shown to manifest itself after antisecretory therapy withdrawal as rebound acid hypersecretion (RAH). Various studies have quantified acid hypersecretion after the cessation of therapy with H(2) antagonists and proton-pump inhibitors (PPIs). While most of those studies had small patient numbers, the findings generally demonstrate that RAH after H(2) antagonist therapy is of low magnitude, short duration, and has questionable clinical significance. On the contrary, acid hypersecretion after PPI therapy is more pronounced, lasts longer, and could possibly be the cause of acid-related symptoms. Potential for causing symptoms has recently been confirmed in two randomized placebo-controlled studies, and while we witness the increasing use of PPIs, RAH could become a proven cause of failure to withdraw therapy in a proportion of patients with reflux or dyspeptic symptoms. PMID:22095014

Leroti?, Ivan; Barši?, Neven; Stojsavljevi?, Sanja; Duvnjak, Marko

2011-11-16

225

Nucleic acid molecule  

US Patent & Trademark Office Database

The invention relates to an isolated nucleic acid molecule encoding a polypeptide capable of producing a triterpenoid hydrocarbon. The invention also relates to the encoded polypeptide, a vector comprising the nucleic acid molecule, a recombinant non-human organism comprising the nucleic acid molecule, and to methods of producing a triterpenoid hydrocarbon or an intermediate of biofuel using the nucleic acid molecule, polypeptide or recombinant organism.

Ball; Andrew (Bedford Park, AU); Moore; Robert (Bedford Park, AU); Knowles; Gregory (Bedford Park, AU); Qin; Jian (Bedford Park, AU)

2011-10-11

226

Plant fatty acid hydroxylases  

DOEpatents

This invention relates to plant fatty acyl hydroxylases. Methods to use conserved amino acid or nucleotide sequences to obtain plant fatty acyl hydroxylases are described. Also described is the use of cDNA clones encoding a plant hydroxylase to produce a family of hydroxylated fatty acids in transgenic plants. In addition, the use of genes encoding fatty acid hydroxylases or desaturases to alter the level of lipid fatty acid unsaturation in transgenic plants is described.

Somerville, Chris (Portola Valley, CA); Broun, Pierre (Burlingame, CA); van de Loo, Frank (Lexington, KY)

2001-01-01

227

Quinolinic acid, ?-picolinic acid, fusaric acid, and 2,6-pyridinedicarboxylic acid enhance the Fenton reaction in phosphate buffer  

Microsoft Academic Search

Quinolinic acid, ?-picolinic acid, fusaric acid, and 2,6-pyridinedicarboxylic acid enhanced the Fenton reaction in phosphate buffer, respectively. The enhancement by quinolinic acid, ?-picolinic acid, fusaric acid, and 2,6-pyridinedicarboxylic acid of the Fenton reaction may be partly related to their respective actions in the biological systems such as a neurotoxic effect (quinolinic acid), a marked growth-inhibitory action on rice seeding (?-picolinic

Hideo Iwahashi; Hiroyuki Kawamori; Kazuaki Fukushima

1999-01-01

228

The Acid Rain Reader.  

ERIC Educational Resources Information Center

|A topic which is often not sufficiently dealt with in elementary school textbooks is acid rain. This student text is designed to supplement classroom materials on the topic. Discussed are: (1) "Rain"; (2) "Water Cycle"; (3) "Fossil Fuels"; (4) "Air Pollution"; (5) "Superstacks"; (6) "Acid/Neutral/Bases"; (7) "pH Scale"; (8) "Acid Rain"; (9)…

Stubbs, Harriett S.; And Others

229

What Is Acid Rain?  

ERIC Educational Resources Information Center

|Acid rain is the collective term for any type of acidified precipitation: rain, snow, sleet, and hail, as well as the presence of acidifying gases, particles, cloud water, and fog in the atmosphere. The increased acidity, primarily from sulfuric and nitric acids, is generated as a by-product of the combustion of fossil fuels such as coal and oil.…

Likens, Gene E.

2004-01-01

230

Bile acid diarrhea.  

PubMed

Bile acids normally undergo enterohepatic circulation. When this circulation is interrupted, bile acids enter the colon in increased concentrations. Here, they produce Cl- secretion by a calcium- and cyclic AMP-dependent mechanism, resulting in diarrhea. Cholestasis may lead to serum bile acid concentrations high enough to produce colonic secretion by serosal surface effects. When resection or disease interferes with ileal function, the resulting diarrhea can be clearly attributed to bile acid malabsorption. In other states, such as postcholecystectomy diarrhea and idiopathic bile acid diarrhea, the role of bile acids is less well defined. 23-75Selena-25-homotaurocholic acid provides a way of tracing the metabolism of bile acids and their enterohepatic circulation in vivo. Metabolized similarly to natural bile acids, its circulation is easily traced by scintigraphy. Barium x-rays, serum concentrations of bile acids or bile acid intermediates, and tests of vitamin B12 absorption provide indirect measures of ileal function. Careful history and examination combined with one of many the available tests of ileal function allow a diagnosis. A therapeutic trial with a bile acid binding resin confirms the impression and treats the diarrhea. PMID:9571377

Potter, G D

231

Acid (and Base) Rainbows  

NSDL National Science Digital Library

Learners use red cabbage juice and pH indicator paper to test the acidity and basicity of household materials. The activity links this concept of acids and bases to acid rain and other pollutants. Resource contains vocabulary definitions and suggestions for assessment, extensions, and scaling for different levels of learners.

Kolenbrander, Amy; Yowell, Janet; Mach, Natalie; Zarske, Malinda S.; Carlson, Denise; Perez, Sharon

2004-01-01

232

[alpha]-Oxocarboxylic Acids  

ERIC Educational Resources Information Center

|Several [alpha]-oxocarboxylic acids play key roles in metabolism in plants and animals. However, there are inconsistencies between the structures as commonly portrayed and the reported acid ionization constants, which result because the acids are predominantly hydrated in aqueous solution; that is, the predominant form is RC(OH)[subscript 2]COOH…

Kerber, Robert C.; Fernando, Marian S.

2010-01-01

233

Uric acid nephrolithiasis.  

PubMed

Uric acid is the end-product of purine nucleotide metabolism in man. The renal handling of urate is a complicated process, resulting in a fractional clearance of 8.2-10.3%. The anhydrous form is thermodynamically the most stable uric acid crystal. Uric acid is a weak acid that ionizes with a Pka at pH 5.75. At the normal acidic region, uric acid solubility is strongly increased by urinary pH. The prevalence of uric acid stones varies between countries, reflecting climatic, dietary, and ethnical differences, ranging from 2.1% (in Texas) to 37.7% (in Iran). The risk for uric acid stone formation correlates with the degree of uric acid supersaturation in the urine, depending on uric acid concentration and urinary pH. Hyperuricosuria is the major risk factor, the most common cause being increased purine intake in the diet. Acquired and hereditary diseases accompanied by hyperuricosuria and stone disease include: gout, in strong correlation with the amount of uric acid excreted, myelo- and lymphoproliferative disorders, multiple myeloma, secondary polycythemia, pernicious anemia and hemolytic disorders, hemoglobinopathies and thalassemia, the complete or partial deficiency of HGPRT, superactivity of PRPP synthetase, and hereditary renal hypouricemia. A common denominator in patients with idiopathic and gouty stone formers is a low urinary pH. Uric acid nephrolithiasis is indicated in the presence of a radiolucent stone, a persistent undue urine acidity and uric acid crystals in fresh urine samples. A radiolucent stone in combination with normal or acidic pH should raise the possibility of urate stones.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7783706

Halabe, A; Sperling, O

1994-01-01

234

Acid Strengths of Some Substituted Picric Acids.  

National Technical Information Service (NTIS)

The aqueous dissociation constants for a number of substituted picric acids and related compounds were determined spectrophotometrically, and the values obtained correlated with the mid-equivalence potentials obtained by half-neutralization in acetone sol...

P. J. Pearce R. J. J. Simkins

1968-01-01

235

Editorial: Acid precipitation  

SciTech Connect

This editorial focuses on acid rain and the history of public and governmental response to acid rain. Comments on a book by Gwineth Howell `Acid Rain and Acid Waters` are included. The editor feels that Howells has provide a service to the environmental scientific community, with a textbook useful to a range of people, as well as a call for decision makers to learn from the acid rain issue and use it as a model for more sweeping global environmental issues. A balance is needed among several parameters such as level of evidence, probability that the evidence will lead to a specific direction and the cost to the global community. 1 tab.

NONE

1995-09-01

236

Equilibrium fracture acidizing  

SciTech Connect

This patent describes a method for acidizing a formation penetrated by a well comprising: injecting acid into the formation at a pressure sufficient to initiate and propagate a fracture in the formation; reducing the injection rate of the acid into the fracture to a rate sufficient to hold the fracture open without significant further extension, such that the acid contacts and etches the fracture; and reducing the injection rate of the acid into the fracture to a rate that is sufficient to hold the fracture open.

Tinker, S.J.

1989-06-06

237

Association of the Herpes Simplex Virus Type 1 Us11 Gene Product with the Cellular Kinesin Light-Chain-Related Protein PAT1 Results in the Redistribution of Both Polypeptides  

Microsoft Academic Search

The herpes simplex virus type 1 (HSV-1) Us11 gene encodes a multifunctional double-stranded RNA (dsRNA)- binding protein that is expressed late in infection and packaged into the tegument layer of the virus particle. As a tegument component, Us11 associates with nascent capsids after its synthesis late in the infectious cycle and is delivered into newly infected cells at times prior

Louisa Benboudjema; Matthew Mulvey; Yuehua Gao; Sanjay W. Pimplikar; Ian Mohr

2003-01-01

238

[Uric acid nephrolithiasis].  

PubMed

Uric acid nephrolithiasis is frequent accounting for 10% of urinary stones in industrialized countries. Its frequency will increase in the next decades because of the ageing and the increasing prevalence of obesity and type 2 diabetes mellitus. The pathophysiologic defect is an excessively acidic urine pH rather than hyperuricosuria. Undissociated uric acid is poorly soluble in acidic urines (pH < 5.5) but solubility increases when sodium urate forms at higher pH. Insulin resistance may contribute to the development of acidic urine because of higher net acid excretion. Because uric acid kidney stones are radiolucent, diagnosis is based on echography and tomodensitometry. Medical management strategies focus primarily on alkali treatment and/or decreasing hyper-uricosuria. PMID:21563421

Dussol, Bertrand

2011-03-01

239

Process for the preparation of lactic acid and glyceric acid  

DOEpatents

Hexose and pentose monosaccharides are degraded to lactic acid and glyceric acid in an aqueous solution in the presence of an excess of a strongly anionic exchange resin, such as AMBERLITE IRN78 and AMBERLITE IRA400. The glyceric acid and lactic acid can be separated from the aqueous solution. Lactic acid and glyceric acid are staple articles of commerce.

Jackson, James E [Haslett, MI; Miller, Dennis J [Okemos, MI; Marincean, Simona [Dewitt, MI

2008-12-02

240

The Enzymic Conversion of the Tartaric Acids to Oxaloacetic Acid  

Microsoft Academic Search

SUMMARY: Certain bacteria of the genus Pseudomonas attack the tartaric acids by means of inducible stereospecific dehydrases. Each dehydrase converts its specific isomeric substrate to oxaloacetic acid ; in crude cell-free extracts the oxaloacetic acid is in turn converted to pyruvic acid, which accumulates. By treatment of the crude extracts with ethylenediaminetetraacetic acid (EDTA), substantial accumulations of oxaloacetic acid can

M. SHILO

1957-01-01

241

Isoprenoid Acids in Recent Sediments.  

National Technical Information Service (NTIS)

Phytanic acid, pristanic acid, and 4,8,12-trimethyltridecanoic acid have been isolated from three recent marine sediments. The ratio of palmitic to pristanic acid is similar to that encountered in typical marine lipids. This suggests a biochemical origin ...

M. Blumer W. J. Cooper

1968-01-01

242

Fatty acids and neurodevelopment.  

PubMed

Knowledge of the importance of docosahexaenoic acid (DHA), arachidonic acid (AA), and long-chain polyunsaturated fatty acids (LCPUFAs) in neurodevelopment was originally obtained from animal studies. These fatty acids are rapidly accreted in brain during the first postnatal year in animal and human infants, and they are found in high concentrations in breast milk. Reports of enhanced intellectual development in breast-fed children, and reports linking LCPUFA deficiency with neurodevelopmental disorders have stressed the physiological importance of DHA in visual and neural systems. In addition to high concentrations of fatty acids in breast milk, they are also present in fish and algae oil and have recently been added to infant formulas. Esterified poplyunsaturated fatty acids act in cellular membranes, in signal transduction, in neurotransmission, and in the formation of lipid rafts. Nonesterified polyunsaturated fatty acids can modulate gene expression and ion channel activities, thus becoming neuroprotective agents. The conversion of linoleic acid and alpha-linolenic acid into ARA and DHA have led to randomized clinical trials that have studied whether infant formulas supplemented with DHA or both DHA and ARA would enhance visual and cognitive development. This review gives an overview of fatty acids and neurodevelopment, focusing on the findings from these studies. PMID:18667917

Belkind-Gerson, J; Carreón-Rodríguez, A; Contreras-Ochoa, C O; Estrada-Mondaca, S; Parra-Cabrera, M S

2008-08-01

243

Lewis Acid Organocatalysts  

NASA Astrophysics Data System (ADS)

The term Lewis acid catalysts generally refers to metal salts like aluminium chloride, titanium chloride and zinc chloride. Their application in asymmetric catalysis can be achieved by the addition of enantiopure ligands to these salts. However, not only metal centers can function as Lewis acids. Compounds containing carbenium, silyl or phosphonium cations display Lewis acid catalytic activity. In addition, hypervalent compounds based on phosphorus and silicon, inherit Lewis acidity. Furthermore, ionic liquids, organic salts with a melting point below 100 °C, have revealed the ability to catalyze a range of reactions either in substoichiometric amount or, if used as the reaction medium, in stoichiometric or even larger quantities. The ionic liquids can often be efficiently recovered. The catalytic activity of the ionic liquid is explained by the Lewis acidic nature of their cations. This review covers the survey of known classes of metal-free Lewis acids and their application in catalysis.

Sereda, Oksana; Tabassum, Sobia; Wilhelm, René

244

Acid rain reports  

NASA Astrophysics Data System (ADS)

Three independent reports on acid precipitation issued in June reinforce each other and, taken together, support those seeking immediate action to curb man-generated acid deposition in northeastern North America by reducing emissions of sulfur and nitrogen oxides. The Interagency Task Force on Acid Precipitation report concluded that manmade pollution is to blame for acid precipitation problems in the northeastern United States. A National Research Council (NRC) committee stated that reducing the manmade emissions of sulfur and nitrogen oxides will result in a proportional reduction in the deposition of acid precipitation. And an acid rain panel assembled by the White House Office of Science and Technology Policy (OSTP) called for immediate action to curb the emissions despite incomplete scientific data.

Richman, Barbara T.

245

Kidney amino acid transport  

Microsoft Academic Search

Near complete reabsorption of filtered amino acids is a main specialized transport function of the kidney proximal tubule.\\u000a This evolutionary conserved task is carried out by a subset of luminal and basolateral transporters that together form the\\u000a transcellular amino acid transport machinery similar to that of small intestine. A number of other amino acid transporters\\u000a expressed in the basolateral membrane

François Verrey; Dustin Singer; Tamara Ramadan; Raphael N. Vuille-dit-Bille; Luca Mariotta; Simone M. R. Camargo

2009-01-01

246

Chronic valproic acid intoxication.  

PubMed

Valproic acid intoxication may be associated with cerebral, cardiovascular, respiratory, gastrointestinal, and hematologic complications. We report a case of a 7-year-old girl, epilepsy-treated chronically with valproic acid, sulthiame, and clonazepam, who presented to the emergency room because of a global deterioration during the preceding 2 months, including poorer feeding and worsened general responsiveness. The girl was later diagnosed to have chronic valproic acid intoxication. PMID:23736073

Weiner, Dror; Nir, Vered; Klein-Kremer, Adi; Kassem, Eiass

2013-06-01

247

Acid rain on Bermuda  

Microsoft Academic Search

Increased acidity of precipitation due to combustion of fossil fuels has been well documented for both the eastern USA1 and Canada2. The SO2 and NOxemitted by the burning of coal, natural gas, fuel oil and petrol are oxidized in the atmosphere to sulphuric and nitric acids which subsequently give rise to acid precipitation1. However, the SO2 and NOx emitted, and

Timothy Jickells; Anthony Knap; Thomas Church; James Galloway; John Miller

1982-01-01

248

Preparation of petroselinic acid  

Microsoft Academic Search

Petroselinic acid of a grade which is suitable for most laboratory applications has been prepared by a single crystallization\\u000a of the mixed fatty acids of parsley seed oil from 90% ethanol. A product of higher purity has been prepared from this acid\\u000a by application of urea segregation techniques for the removal of saturated materials. No evidence of the presence of

Sara P. Fore; Raiford L. Holmes; W. G. Bickford

1960-01-01

249

Well acidization with alpha-hydroxysulfonic acid  

SciTech Connect

This patent describes a well treating process in which fluid is injected into a well and flowed into contact with acidifiable material in and around a portion of the well within a subterranean earth formation in order to contact the acidifiable material with at least one strong acid. An improved process for controlling the rate of the acidification reaction comprises: flowing fluid inclusive of water, SO/sub 2/ and carbonyl compound into the well and into and out of contact with the acidifiable material with the composition of the fluid arranged so that, in contact with the acidifiable material, the fluid consists essentially of an acidic solution of water, SO/sub 2/ and carbonyl compound in equilibrium with at least one reactively formed alpha-hydroxysulfonic acid.

Slaugh, L.H.

1987-06-02

250

Aristolochic Acid: Safety Alert  

Center for Food Safety and Applied Nutrition (CFSAN)

... Section Contents Menu. Recalls, Outbreaks & Emergencies. Safety Alerts & Advisories. -. Aristolochic Acid: Safety Alert. FDA ... More results from www.fda.gov/food/recallsoutbreaksemergencies/safetyalertsadvisories

251

Recovery of organic acids  

SciTech Connect

A method is disclosed for the recovery of an organic acid from a dilute salt solution in which the cation of the salt forms an insoluble carbonate salt. A tertiary amine and CO.sub.2 are introduced to the solution to form the insoluble carbonate salt and a complex between the acid and an amine. A water immiscible solvent, such as an alcohol, is added to extract the acid/amine complex from the dilute salt solution to a reaction phase. The reaction phase is continuously dried and a product between the acid and the solvent, such as an ester, is formed.

Verser, Dan W. (Menlo Park, CA); Eggeman, Timothy J. (Lakewood, CO)

2011-11-01

252

Recovery of organic acids  

DOEpatents

A method is disclosed for the recovery of an organic acid from a dilute salt solution in which the cation of the salt forms an insoluble carbonate salt. A tertiary amine and CO.sub.2 are introduced to the solution to form the insoluble carbonate salt and a complex between the acid and an amine. A water immiscible solvent, such as an alcohol, is added to extract the acid/amine complex from the dilute salt solution to a reaction phase. The reaction phase is continuously dried and a product between the acid and the solvent, such as an ester, is formed.

Verser, Dan W. (Golden, CO); Eggeman, Timothy J. (Lakewood, CO)

2009-10-13

253

Acidizing concentrates for oil well acidizing systems  

SciTech Connect

An acidizing composition is described for treating oil-bearing formations comprising: (a) from about 90 to about 99.99 percent by volume of an aqueous acid solution; and (b) from about 0.01 to about 10 percent by weight of an acidizing concentrate consisting of: a mixture of a branched-aliphatic C/sub 3/-C/sub 6/ alcohol and a branched aliphatic C/sub 7/-C/sub 10/ alcohol; and an effective amount of a non-ionic polyether surfactant to render the alcohols soluble in the acid. The surfactant has the formula: R is the oxyalkylation residue of a C/sub 2/-C/sub 10/ diol or triol; n is an integer of 2 or 3, X and Y are numbers such that the ratio of X to Y is from 8:1 to 0.3:1; and the total molecular weight of the molecule is from 1,000 to 15,000. The weight ratio of the mixture of alcohols to the nonionic surfactant is from 10:1 to 1:10. The composition is capable of dissolving sludge deposits in the oil-bearing formations.

Crema, S.C.

1987-06-30

254

Strong Acids (GCMP)  

NSDL National Science Digital Library

Strong Acids: this is a resource in the collection "General Chemistry Multimedia Problems". This problem will explore the properties of common strong acids. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

255

Acids and Salts (GCMP)  

NSDL National Science Digital Library

Acids and Salts: this is a resource in the collection "General Chemistry Multimedia Problems". This problem will explore a few properties of common acids and their salts. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

256

Facts about Folic Acid  

MedlinePLUS

... INFO (800-232-4636) TTY: (888) 232-6348 Contact CDC-INFO flo@cdc.gov Folic Acid Homepage Facts Quiz Questions & Answers Cereals with Folic Acid Data and Statistics Research Global Initiative Articles & Key Findings Recommendations Free Materials Links ...

257

Folic Acid Quiz  

MedlinePLUS

... INFO (800-232-4636) TTY: (888) 232-6348 Contact CDC-INFO flo@cdc.gov Folic Acid Homepage Facts Quiz Questions & Answers Cereals with Folic Acid Data and Statistics Research Global Initiative Articles & Key Findings Recommendations Free Materials Links ...

258

Acid rain options  

SciTech Connect

A number of contributions made to a series of seminars on acid rain options held by the Air Pollution Control Association are presented. They include statements on US and Canadian policy and legislation, and views from coal producers, electric utilities and motor vehicle manufacturers on measures to counteract or prevent the effects of acid rain.

Perhac, R.M.

1985-03-01

259

Azelaic Acid Topical  

MedlinePLUS

Finacea® Gel ... Azelaic acid gel is used to clear the bumps, lesions, and swelling caused by rosacea (a skin disease that causes redness, ... Azelaic acid comes as a gel and a cream to apply to the skin. It is usually applied twice a day, in the morning and the evening. ...

260

EFFECTS OF ACID PRECIPITATION  

EPA Science Inventory

Recent reviews of available data indicate that precipitation in a large region of North America is highly acidic when its pH is compared with the expected pH value of 5.65 for pure rain water in equilibrium with CO2. A growing body of evidence suggests that acid rain is responsib...

261

(Acid rain workshop)  

Microsoft Academic Search

The traveler presented a paper entitled Susceptibility of Asian Ecosystems to Soil-Mediated Acid Rain Damage'' at the Second Workshop on Acid Rain in Asia. The workshop was organized by the Asian Institute of Technology (Bangkok, Thailand), Argonne National Laboratory (Argonne, Illinois), and Resource Management Associates (Madison, Wisconsin) and was sponsored by the US Department of Energy, the United Nations Environment

1990-01-01

262

Acid in water  

NSDL National Science Digital Library

Plants and animals that live in water create some amount of acid in the water. The carbon dioxide that plants and animals release into the water makes the water acidic and unsafe for living organisms. This is why the water of captive aquatic animals and plants must be changed often.

Laszlo Ilyes (None;)

2007-05-16

263

Amino acids: Analytical aspects  

Microsoft Academic Search

This workshop was organized as a direct response to concerns and queries raised by laboratory personnel, both in Europe and in the United States, about the imminent withdrawal of Beckman Coulter from the amino acid analysis market. The topics covered included external quality control schemes, standard operating procedures for amino acid analysis and instrumentation, both from a user's perspective and

P. D. Mayne; G. Roche; D. Deverell

2001-01-01

264

EXPOSURES TO ACIDIC AEROSOLS  

EPA Science Inventory

Ambient monitoring of acid aerosol in four U.S. cities and in a rural region of southern Ontario clearly show distinct periods of strong acidity. easurements made in Kingston, TN, and Stuebenville, OH, resulted in 24-hr H+ ion concentrations exceeding 100 nmole/m3 more than 10 ti...

265

Toxicology of Perfluoroalkyl acids  

EPA Science Inventory

The Perfluoroalkyl acids(PFAAs) area a family of organic chemicals consisting of a perflurinated carbon backbone (4-12in length) and a acidic functional moiety (Carboxylate or sulfonate). These compounds have excellent surface-tension reducing properties and have numerous industr...

266

Toxicology of Perfluoroalkyl Acids*  

EPA Science Inventory

The perfluoroalkyl acids (PFAAs) are a family of organic chemicals consisting of a perfluorinated carbon backbone (4-12 in length) and an acidic functional moiety (carboxylate or sulfonate). These compounds are chemically stable, have excellent surface-tension reducing properties...

267

Fats and fatty acids  

Technology Transfer Automated Retrieval System (TEKTRAN)

The absolute fat requirement of the human species is the amount of essential fatty acids needed to maintain optimal fatty acid composition of all tissues and normal eicosanoid synthesis. At most, this requirement is no more than about 5% of an adequate energy intake. However, fat accounts for appro...

268

Metabolism of Acid Mucopolysaccharides  

PubMed Central

The biosynthesis of the acid mucopolysaccharides, hyaluronic acid and chondroitin sulfuric acid, occurs by way of uridine nucleotides which contain the monosaccharide units of the respective polysaccharides. The mechanism of alternation of groups is as yet unknown. Certain of the acid mucopolysaccharides are covalently bound to protein by way of serine. In the case of the protein-polysaccharide complex of cartilage, there is evidence to suggest that the polysaccharide may be linked to the serine by way of galactose. Chondroitin sulfuric acid B may be isolated almost free of amino acids from the tissues and urine of patients with the Hurler syndrome without the use of proteolytic enzymes, acid, or alkali. This contrasts markedly with the tight binding of this compound to protein in normal tissue. It is suggested that the metabolic defect in this disease may reside in a defect of the peptide or linkage of the peptide to polysaccharide resulting in failure of the acid mucopolysaccharide to be fixed normally in connective tissue. Such a defect may result in interference with normal regulation of polysaccharide synthesis with a resultant increased synthesis. It is proposed that such a mechanism may obtain in other heritable connective tissue diseases as well as other storage diseases.

Dorfman, Albert

1964-01-01

269

Amino Acid Crossword Puzzle  

ERIC Educational Resources Information Center

|Learning the 20 standard amino acids is an essential component of an introductory course in biochemistry. Later in the course, the students study metabolism and learn about various catabolic and anabolic pathways involving amino acids. Learning new material or concepts often is easier if one can connect the new material to what one already knows;…

Sims, Paul A.

2011-01-01

270

Gelatinization with formic acid.  

PubMed

1. A study has been made of the gelatins obtained by treating a number of fresh and fossil collagens with dilute formic acid. 2. Compositions of their peptides separated by filtration through polyacrylamide gels has been established. 3. Solubilization results in the freeing of much aspartic acid and less glycine, the amounts being determined for the collagens investigated. PMID:318457

Wyckoff, R W; Davidson, F D

1979-01-01

271

Silicic acid: boric acid complexes as wood preservatives  

Microsoft Academic Search

Wood was treated with a low molecular-weight silicic acid: boric acid agent and examined for increased resistance to termites and combustion. Wood treated with silicic acid only exhibited increased termite resistance, but not to the marked extent observed after treatment with a mixture of silicic and boric acids. Increasing the quantity of boric acid also increased the termite mortality rate

Haruhiko Yamaguchi

2003-01-01

272

Docosahexaenoic acid and arachidonic acid in infant development  

Microsoft Academic Search

Docosahaxaenoic acid and arachidonic acid are highly concentrated in the central nervous system. The amount of these fatty acids in the central nervous system increases dramatically during the last intrauterine trimester and the first year of life. A central question of research conducted during the past 20 years is if the essential fatty acid precursor of docosahexaenoic acid is sufficient

Susan E. Carlson

2001-01-01

273

Acid rain trends summarized  

NASA Astrophysics Data System (ADS)

In the northeastern United States, the acidity of precipitation has changed little in recent years, although the acidity is increasing in other regions. That's the latest word from a comprehensive review by the U.S. Geological Survey (USGS) of more than 200 published reports of acid rain research from the past 30 years. The report contributes to the controversy over whether increased sulfur emissions from Midwest powerplants increase the acidity of precipitation in the Northeast.“When the results of the many individual studies are combined, they show that acidification of precipitation in the Northeast, which has the most damaging level of acidity on a regional basis, occurred primarily before the mid-1950's and has been largely stabilized since the mid-1960s,” said John T. Turk, a research hydrologist at the USGS Denver office and author of the 18-page summary report.

274

Energy and acid rain  

SciTech Connect

Acid rain is one of the foremost environmental issues of the 1980s and will be of continuining importance to energy policy for several reasons. First, the pollutants that cause acid rain are projected to increase through the end of the century as the demand for energy grows and as coal replaces oil. Second, many of the effects of acid rain are cumulative, so that even at current levels of emissions the problem is expected to intensify and to spread geographically. Third, the transport of air pollutants across state and national boundaries has raised fundamental issues of equity that are likely to be disputed for some time. Finally, any serious program for reducing acid rain will exert a profound influence on the future development of energy supplies. This review summarizes the causes, effects, and transport of acid rain, and discusses possible strategies for mitigating the problem.

Gould, R.R.

1984-01-01

275

Acid Rain Revisited  

NSDL National Science Digital Library

The results of a long term study of the effects of acidic deposition in the Northeast were published in Bioscience this week, and they suggest that forests, lakes, and streams of the Northeastern US are not recovering from the toxic effects of acid rain despite significant cuts in the power plant emissions of sulfur dioxide and nitrogen oxide -- two major contributors to the problem. "Acid rain," more accurately called acidic deposition, causes toxic forms of aluminum to concentrate in soil and water, vital calcium and magnesium to be leached from trees, and surface waters to become inhospitable to aquatic biota. The study showed that, after 30 years of federally mandated air emission reductions, sulfur dioxide emissions have decreased while nitrogen oxide emissions have remained the same and that acidic deposition-related problems continue to plague New York and New England.

Sanders, Hilary C.

2001-01-01

276

Fatty Acid Production from Amino Acids and ?-Keto Acids by Brevibacterium linens BL2†  

PubMed Central

Low concentrations of branched-chain fatty acids, such as isobutyric and isovaleric acids, develop during the ripening of hard cheeses and contribute to the beneficial flavor profile. Catabolism of amino acids, such as branched-chain amino acids, by bacteria via aminotransferase reactions and ?-keto acids is one mechanism to generate these flavorful compounds; however, metabolism of ?-keto acids to flavor-associated compounds is controversial. The objective of this study was to determine the ability of Brevibacterium linens BL2 to produce fatty acids from amino acids and ?-keto acids and determine the occurrence of the likely genes in the draft genome sequence. BL2 catabolized amino acids to fatty acids only under carbohydrate starvation conditions. The primary fatty acid end products from leucine were isovaleric acid, acetic acid, and propionic acid. In contrast, logarithmic-phase cells of BL2 produced fatty acids from ?-keto acids only. BL2 also converted ?-keto acids to branched-chain fatty acids after carbohydrate starvation was achieved. At least 100 genes are potentially involved in five different metabolic pathways. The genome of B. linens ATCC 9174 contained these genes for production and degradation of fatty acids. These data indicate that brevibacteria have the ability to produce fatty acids from amino and ?-keto acids and that carbon metabolism is important in regulating this event.

Ganesan, Balasubramanian; Seefeldt, Kimberly; Weimer, Bart C.

2004-01-01

277

Airborne haloacetic acids.  

PubMed

Haloacetic acid (HAA) concentrations were measured in air samples from a semi-rural and a highly urbanized site in southern Ontario throughout 2000 to investigate their sources and gas-particle partitioning behavior. Denuders were efficient for collection of gaseous HAAs, and the particle phase was collected on a downstream quartz filter with negligible breakthrough. Total HAA concentrations (i.e., gas + particles) ranged between <0.025 and 19 ng m(-3) for individual HAAs at both sites. The dominant airborne HAA was monochloroacetic acid (MCA), followed in decreasing order by dichloroacetic acid (DCA), trifluoroacetic acid (TFA), and trichloroacetic acid (TCA). Difluoroacetic acid (DFA), monofluoroacetic acid (MFA), and chlorodifluoroacetic acid (CDFA) were also frequently detected at lower concentrations. Between sites, TFA, DFA, MFA, and TCA concentrations were significantly higher in Toronto, while CDFA concentrations were higher in Guelph. HAAs were primarily in the gas phase all year; however, during colder months, particle-phase HAA concentrations increased relative to the gas phase. Trichloroacetic acid had the highest particle fraction (phi) for all detected HAAs, with a mean phi of 0.51 and 0.56 for Guelph and Toronto, respectively, and both vapor pressure and acid strength appeared to influence gas-particle partitioning. Temporal trends at both sites were partially explained by temperature, short-wave radiation, and particle mass (PM10), leading to indications of the respective sources. A simple deposition model indicated that dry deposition of TFA and TCA should not be neglected in temperate mid-latitude environments and that precipitation concentrations can be successfully predicted by the Henry's law constant. PMID:12875391

Martin, Jonathan W; Mabury, Scott A; Wong, Charles S; Noventa, Francis; Solomon, Keith R; Alaee, Mehran; Muir, Derek C G

2003-07-01

278

Glycidyl Esters of Aromatic Acids  

Microsoft Academic Search

The reaction of substituted benzoic acids, dicarboxylic acids such as phthalic, terephthalic, and isophthalic acids, and the sodium or potassium salts of these acids with equimolar or excess epichlorohydrin in the presence of benzyltrimethylammonium chloride has been studied using various solvents such as toluene, dioxane, monochlorobenzene, and tetrachloroethylene. Use of the free carboxylic acids gave only fair to low yields

Yoshio Tanaka; Hiroshi Kakiuchi

1967-01-01

279

Strongly Acidic Auxin Indole-3-Methanesulfonic Acid  

PubMed Central

A radiochemical synthesis is described for [14C]indole-3-methanesulfonic acid (IMS), a strongly acidic auxin analog. Techniques were developed for fractionation and purification of IMS using normal and reverse phase chromatography. In addition, the utility of both Fourier transform infrared spectrometry and fast atom bombardment mass spectrometry for analysis of IMS has been demonstrated. IMS was shown to be an active auxin, stimulating soybean hypocotyl elongation, bean first internode curvature, and ethylene production. IMS uptake by thin sections of soybean hypocotyl was essentially independent of solution pH and, when applied at a 100 micromolar concentration, IMS exhibited a basipetal polarity in its transport in both corn coleoptile and soybean hypocotyl sections. [14C]IMS should, therefore, be a useful compound to study fundamental processes related to the movement of auxins in plant tissues and organelles.

Cohen, Jerry D.; Baldi, Bruce G.; Bialek, Krystyna

1985-01-01

280

Antioxidant activity of caffeic acid (3,4-dihydroxycinnamic acid)  

Microsoft Academic Search

Caffeic acid (3,4-dihydroxycinnamic acid) is among the major hydroxycinnamic acids present in wine; sinapic acid, which is a potent antioxidant. It has also been identified as one of the active antioxidant. In the present study, the antioxidant properties of the caffeic acid were evaluated by using different in vitro antioxidant assays such as 2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging, 1,1-diphenyl-2-picryl-hydrazyl free

?lhami Gülçin

2006-01-01

281

Ceric acid decontamination of nuclear reactors  

SciTech Connect

This patent describes a composition, it consists of water; about 0.5 to about 3% by weight of a ceric acid selected from the group consisting of tetrasulfato ceric acid, hexasulfamato ceric acid, hexaperchlorato ceric acid, and mixtures thereof; and about 1 to about 5% by weight of an inorganic acid. The inorganic acid is sulfuric acid when the ceric acid is tetrasulfato ceric acid, sulfamic acid when the ceric acid is hexasulfamato ceric acid, perchloric acid when the ceric acid is a mixture selected from the group consisting of tetrasulfato ceric acid, hexasulfamato ceric acid, and hexaperchlorato ceric acid.

Murray, A.P; Slater, C.G.; White, R.W.

1989-11-14

282

Acid rain agreement  

SciTech Connect

Scientific working groups from Canada and the US have been established to prepare for acid rain negotiations scheduled for June 1981. The groups will take air samples and estimate impact of acid rain on the environment, determine the precise origin of acid rain, and develop a strategy for abatement. Some constraints on the negotiations are costs (potentially $400-500 million for Canada and 5 to 8 times that for the US between now and 2000), the relative independence of Canada's provinces, and the US utility lobby.

Smith, R.J.

1980-08-22

283

Citric acid production.  

PubMed

Citric acid is a commodity chemical produced and consumed throughout The World. It is used mainly in the food and beverage industry, primarily as an acidulant. Although it is one of the oldest industrial fermentations, its World production is still in rapid increasing. Global production of citric acid in 2007 was over 1.6 million tones. Biochemistry of citric acid fermentation, various microbial strains, as well as various substrates, technological processes and product recovery are presented. World production and economics aspects of this strategically product of bulk biotechnology are discussed. PMID:17875481

Berovic, Marin; Legisa, Matic

2007-01-01

284

WASTE ACID DETOXIFICATION AND RECLAMATION  

EPA Science Inventory

This Environmental Security Technology Certification Program (ESTCP) project demonstrated the Waste Acid Detoxification and Reclamation (WADR) systems ability to recover waste electropolish acid solutions generated during the manufacturing of gun-tubes, and reuse the clean acid. ...

285

Atmospheric chemistry: Natural atmospheric acidity  

NASA Astrophysics Data System (ADS)

Formic acid exerts a significant influence on atmospheric chemistry and rainwater acidity. Satellite observations and model simulations suggest that terrestrial vegetation accounts for around 90% of the formic acid produced annually.

Millet, Dylan B.

2012-01-01

286

Hydroxy-Conjugated Fatty Acids.  

National Technical Information Service (NTIS)

This invention relates to a method of producing hydroxy-conjugated octadecadienoic acid from linoleic acid contained in vegetable oils and soap stocks from alkali-refined vegetable oils. Linoleic acid soaps are dispersed in an aqueous medium containing di...

E. A. Emkeu

1973-01-01

287

Acid Hydrolysis of Wood.  

National Technical Information Service (NTIS)

A series of investigations into the acid hydrolysis of pinus radiata (Monterey pine) and the results therefrom are described. Main objectives of the investigation were to establish, using the most promising routes, the conditions of hydrolysis that would ...

A. L. Titchener B. K. Guha

1981-01-01

288

Aristolochic Acid: Safety Alert  

Center for Food Safety and Applied Nutrition (CFSAN)

... Section Contents Menu. Recalls, Outbreaks & Emergencies. Safety Alerts & Advisories. -. Aristolochic Acid: Safety Alert. FDA ... More results from www.fda.gov/food/recalls,%20outbreaks%20&%20emergencies/safetyalertsadvisories

289

Uric acid - blood  

MedlinePLUS

... blood. High levels of uric acid can cause gout or kidney disease. Your doctor may also order ... hyperuricemia) may be due to: Acidosis Alcoholism Diabetes Gout Hypoparathyroidism Lead poisoning Leukemia Nephrolithiasis Polycythemia vera Renal ...

290

Trans fatty acids (image)  

MedlinePLUS

Trans fatty acids are manufactured fats created during a process called hydrogenation, which is aimed at stabilizing polyunsaturated oils to prevent them from becoming rancid and to keep them solid at room temperature. They may ...

291

Nucleic Acids for Computation  

NASA Astrophysics Data System (ADS)

Nucleic acids have many features that are ideal for molecular computation. Using nucleic acids, we have constructed a full set of molecular logic gates, with modular stem-loop-controlled deoxyribozymes as switches and single-stranded oligonucleotides as inputs and outputs. These gates have been combined to form basic computational circuits, including a half- and a full-adder, and can also be assembled into automata to perform complex computational tasks such as game playing. Our most advanced automaton to-date integrates more than 100 nucleic acid logic gates to play a complete game of tic-tac-toe encompassing 76 possible game plays. Inputs and outputs can also be coupled with upstream and downstream components, such as aptamers, sensors, secondary gate activation, and small-molecule release, indicating the potential for nucleic acid computation in the engineering of autonomous therapeutic and diagnostic molecular devices.

MacDonald, Joanne; Stojanovic, Milan N.

292

Zoledronic Acid Written Request  

Center for Drug Evaluation (CDER)

Text Version... dated April 18, 2006, requesting changes to FDA's August 19, 2002, Written Request for pediatric studies for zoledronic acid, as amended ... More results from www.fda.gov/downloads/drugs/developmentapprovalprocess

293

Polymers for acid thickening  

SciTech Connect

Acids, thickened with branched emulsion or suspension polymers of diallyldimethylammonium chloride are useful as oil well drilling and fracturing fluids for stimulating well production and in other applications, such as thickeners for cosmetics, paints, adhesives, textiles and printing inks.

Dixon, K.W.

1980-09-30

294

(Acid rain workshop)  

SciTech Connect

The traveler presented a paper entitled Susceptibility of Asian Ecosystems to Soil-Mediated Acid Rain Damage'' at the Second Workshop on Acid Rain in Asia. The workshop was organized by the Asian Institute of Technology (Bangkok, Thailand), Argonne National Laboratory (Argonne, Illinois), and Resource Management Associates (Madison, Wisconsin) and was sponsored by the US Department of Energy, the United Nations Environment Program, the United Nations Economic and Social Commission for Asia and the Pacific, and the World Bank. Papers presented on the first day discussed how the experience gained with acid rain in North America and Europe might be applied to the Asian situation. Papers describing energy use projections, sulfur emissions, and effects of acid rain in several Asian countries were presented on the second day. The remaining time was allotted to discussion, planning, and writing plans for a future research program.

Turner, R.S.

1990-12-05

295

Acid Precipitation: A Bibliography.  

National Technical Information Service (NTIS)

This bibliography contains 3197 references to information on various aspects of acid precipitation that have been included in the Department of Energy's Energy Data Base through February 1983. The references cover research reports, journal articles, books...

P. S. Blackburn

1983-01-01

296

Valproic Acid and Pregnancy  

MedlinePLUS

... valproic acid and then had a relapse of bipolar disorder during my pregnancy? Recurrence of depression or mania ... 7. Yonkers KA et al. 2004. Management of bipolar disorders during pregnancy and the postpartum period. Am J ...

297

Acid Mine Drainage Treatment.  

National Technical Information Service (NTIS)

Contaminated water flowing from abandoned coal mines is one of the most significant contributors to water pollution in former and current coal- producing areas. Acid mine drainage (AMD) can have severe impacts to aquatic resources, can stunt terrestrial p...

J. Fripp P. F. Ziemkiewicz H. Charkavorki

2000-01-01

298

Acid prehydrolysis of wood  

Treesearch

Acid pretreatment of wood provides significant energy savings during refining ... reduction in specific refiner energy consumption, with a minor sacrifice in brightness. ... The similarity in behavior of these two pretreatments suggests a common ...

299

Acid Lipase Disease  

MedlinePLUS

... Acid Lipase Disease Information Page Synonym(s): Cholesterol Ester Storage Disease, Wolman’s Disease Table of Contents (click to ... include waxes, oils, and cholesterol. Two rare lipid storage diseases are caused by the deficiency of the ...

300

Acid-Base Tutorial  

NSDL National Science Digital Library

Website for anyone wanting to become more familiar with the physiology of acid-base balance in clinical medicine. Several pages are interactive. Numerical results are accompanied by text interpretations to facilitate recognition and understanding.

MD Alan W. Grogono (Tulane University School of Medicine Dept. of Anesthesiology)

2002-06-01

301

Salicylic Acid Topical  

MedlinePLUS

... skin dryness and scaling), dandruff, corns, calluses, and warts on the hands or feet. Topical salicylic acid should not be used to treat genital warts, warts on the face, warts with hair growing ...

302

Folic acid in diet  

MedlinePLUS

... certain types of anemias . Folate works along with vitamin B12 and vitamin C to help the body break ... Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. National Academy Press, ...

303

Molecular cloning of an intracellular P-type ATPase from Dictyostelium that is up-regulated in calcium-adapted cells.  

PubMed

Results from a number of laboratories suggest that intracellular Ca2+ is involved in the regulation of Dictyostelium discoideum growth and development. To learn more about the regulation and function of intracellular Ca2+ in this organism, we have cloned and sequenced cDNAs that encode a putative P-type Ca2+ ATPase designated patA. The deduced protein product of this gene (PAT1) has a calculated molecular mass of 120,718 daltons. It exhibits about 46% amino acid identity with Ca2+ ATPases of the plasma membrane Ca2+ ATPase family and lower identity with sarco(endo)plasmic reticulum Ca2+ ATPase family members and monovalent cation pumps. However, PAT1 lacks the highly conserved calmodulin-binding domain present in the C-terminal region of most plasma membrane Ca2+ ATPase-type enzymes. When Dictyostelium amoebae are adapted to grow in the presence of 80 mM CaCl2, both the patA message and protein product are up-regulated substantially. These cells also exhibit an increase in the rate and magnitude of intracellular P-type Ca2+ uptake activity. Immunofluorescence analysis indicates that PAT1 colocalizes with bound calmodulin to intracellular membranes, probably components of the contractile vacuole complex. The presence of PAT1 on the contractile vacuole suggests that in Dictyostelium this organelle might function in Ca2+ homeostasis as well as in water regulation. PMID:7499325

Moniakis, J; Coukell, M B; Forer, A

1995-11-24

304

Nucleic Acids for Computation  

Microsoft Academic Search

\\u000a Nucleic acids have many features that are ideal for molecular computation. Using nucleic acids, we have constructed a full\\u000a set of molecular logic gates, with modular stem-loop-controlled deoxyribozymes as switches and single-stranded oligonucleotides\\u000a as inputs and outputs. These gates have been combined to form basic computational circuits, including a half- and a full-adder,\\u000a and can also be assembled into automata

Joanne MacDonald; Milan N. Stojanovic

2009-01-01

305

Biodegradation of polyhydroxyalkanoic acids  

Microsoft Academic Search

Stimulated by the commercial availability of bacteriologically produced polyesters such as poly[(R)-3-hydroxybutyric acid], and encouraged by the discovery of new constituents of polyhydroxyalkanoic acids (PHA), a considerable\\u000a body of knowledge on the metabolism of PHA in microorganisms has accumulated. The objective of this essay is to give an overview\\u000a on the biodegradation of PHA. The following topics are discussed: (i)

D. Jendrossek; A. Schirmer; H. G. Schlegel

1996-01-01

306

Acids of pomegranate peel  

Microsoft Academic Search

the substance were identical with those of ellagic acid. On the basis of the results of a determination of the maximum intensities of the spots (SF-4a at 440 nm) revealed with a 1% solution of iron ammonium alum, it was established that the peel contains0.55% of ellagic acid on the air-dry raw material. The ethereal extract was evaporated to dryness

E. P. Nosacheva; Yu. B. Kerimov; T. N. Bikbulatova

1973-01-01

307

Nucleic acid detection method  

US Patent & Trademark Office Database

A method of detecting a target nucleotide sequence in a nucleic acid molecule, which comprises: (a) binding of an oligonucleotide probe to said nucleic acid molecule; (b) selective labelling of the bound oligonucleotide probe in the presence of said target nucleotide sequence; (c) hybridization of the labelled oligonucleotide to a complementary sequence; and (d) subsequent detection of the label; such methods being suitable for qualitative and quantitative assays of microbiological populations.

Rudi; Knut (Oslo, NO); Jakobsen; Kjetill Sigurd (Olso, NO)

2003-09-09

308

Acid Rain Lesson Plan  

NSDL National Science Digital Library

Five articulated lessons focus on air quality using classroom and field data collection activities. Case study in Great Smoky Mountains has broader application. Background and data for lessons on: the pH scale, understanding acid vs. base, collecting data, mapping relationship of weather events to acid rain. Links to NPS data on air quality, current values, atlas and reports, packaged datasets on ozone, meteorological conditions and other parameters. Also available: teacher resources; educator workshops.

309

Molecular Structure of Gallic acid  

NSDL National Science Digital Library

Gallic acid is found in its free state and combined with the tannin molecule, from which it can be extracted by the hydrolysis of tannic acid with sulfuric acid. Since one molecule of gallic acid has a carboxylic acid group and hydroxyl groups, it can react with another molecule of gallic acid to form an ester, digallic acid. When heated above 200 degrees C, gallic acid loses carbon dioxide to form pyrogallol (1,2,3-trihydroxybenzene, C6H3(OH)3), which is used in the production of azo dyes, photographic developers, and in laboratories for absorbing oxygen.

2003-05-08

310

Portable nucleic acid thermocyclers.  

PubMed

A nucleic acid thermal cycler is considered to be portable if it is under ten pounds, easily carried by one individual, and battery powered. Nucleic acid amplification includes both polymerase chain reaction (e.g. PCR, RT-PCR) and isothermal amplification (e.g. RPA, HDA, LAMP, NASBA, RCA, ICAN, SMART, SDA). There are valuable applications for portable nucleic acid thermocyclers in fields that include clinical diagnostics, biothreat detection, and veterinary testing. A system that is portable allows for the distributed detection of targets at the point of care and a reduction of the time from sample to answer. The designer of a portable nucleic acid thermocycler must carefully consider both thermal control and the detection of amplification. In addition to thermal control and detection, the designer may consider the integration of a sample preparation subsystem with the nucleic acid thermocycler. There are a variety of technologies that can achieve accurate thermal control and the detection of nucleic acid amplification. Important evaluation criteria for each technology include maturity, power requirements, cost, sensitivity, speed, and manufacturability. Ultimately the needs of a particular market will lead to user requirements that drive the decision between available technologies. PMID:24030680

Almassian, David R; Cockrell, Lisa M; Nelson, William M

2013-10-21

311

Acidification and Acid Rain  

NASA Astrophysics Data System (ADS)

Air pollution by acids has been known as a problem for centuries (Ducros, 1845; Smith, 1872; Camuffo, 1992; Brimblecombe, 1992). Only in the mid-1900s did it become clear that it was a problem for more than just industrially developed areas, and that precipitation quality can affect aquatic resources ( Gorham, 1955). The last three decades of the twentieth century saw tremendous progress in the documentation of the chemistry of the atmosphere, precipitation, and the systems impacted by acid atmospheric deposition. Chronic acidification of ecosystems results in chemical changes to soil and to surface waters and groundwater as a result of reduction of base cation supply or an increase in acid (H+) supply, or both. The most fundamental changes during chronic acidification are an increase in exchangeable H+ or Al3+ (aluminum) in soils, an increase in H+ activity (˜concentration) in water in contact with soil, and a decrease in alkalinity in waters draining watersheds. Water draining from the soil is acidified and has a lower pH (=-log [H+]). As systems acidify, their biotic community changes.Acidic surface waters occur in many parts of the world as a consequence of natural processes and also due to atmospheric deposition of strong acid (e.g., Canada, Jeffries et al. (1986); the United Kingdom, Evans and Monteith (2001); Sweden, Swedish Environmental Protection Board (1986); Finland, Forsius et al. (1990); Norway, Henriksen et al. (1988a); and the United States (USA), Brakke et al. (1988)). Concern over acidification in the temperate regions of the northern hemisphere has been driven by the potential for accelerating natural acidification by pollution of the atmosphere with acidic or acidifying compounds. Atmospheric pollution ( Figure 1) has resulted in an increased flux of acid to and through ecosystems. Depending on the ability of an ecosystem to neutralize the increased flux of acidity, acidification may increase only imperceptibly or be accelerated at a rate that endangers the existing biota. Concerns about acid (or acidic) rain in its modern sense were publicized by the Swedish soil scientist Svante Odén (1968). He argued, initially in the Swedish press, that long-term increases in the atmospheric deposition of acid could lower the pH of surface waters, cause a decline in fish stocks, deplete soils of nutrients, and accelerate damage to materials. By the 1970s, acidification of surface waters was reported in many countries in Europe as well as in North America. The late twentieth-century rush to understand the impact of acid rain was driven by: (i) reports of damaged or threatened freshwater fisheries and (ii) damaged forests. Perhaps the earliest linkage between acidic surface water and damage to fish was made by Dahl (1921) in southern Norway. There, spring runoff was sufficiently acidic to kill trout. It was not until the 1970s that a strong link was established between depressed pH, mobilization of aluminum from soil, and fish status ( Schofield and Trojnar,1980). The relationship between acidification of soils and forest health started with hypotheses in the 1960s and has slowly developed. Acid rain enhances the availability of some nutrients (e.g., nitrogen), and may either enhance or diminish the availability of others (e.g., calcium, magnesium, potassium, and phosphorus). Damage to anthropogenic structures, human health, and visibility have also raised concerns. The history of these early developments was summarized by Cowling (1982). Since the 1970s, sulfur and nitrogen emissions to the atmosphere have been reduced by 50-85% and 0-30%, respectively, both in North America and Europe. The emission reductions have occurred as a consequence of knowledge gained and economic factors. While recovery of water quality is underway in some areas, problems of acidification persist, and are now complicated by the effects of climate change ( Schindler, 1997).

Norton, S. A.; Veselã½, J.

2003-12-01

312

Nitric acid-formic acid compatibility in DWPF  

SciTech Connect

The addition of the Nitric Acid Flowsheet to the DWPF feed preparation process introduces nitric acid into a vessel which will subsequently receive a formic acid solution. The combination of these two acids suggests that a denitration reaction might occur. This memorandum reviews the conditions under which a denitration reaction is possible and compares these conditions to DWPF operating conditions.

Eibling, R.E.

1992-10-20

313

Export of Acidity in Drainage Water from Acid Sulphate Soils  

Microsoft Academic Search

Disturbed acid sulphate soils are potent sources of acidity in coastal waterways. Monitoring studies of the drainage water for sites at East Trinity, Cairns and Pimpama, south-east Queensland indicate that considerable acidity is found in the drainage water from these sites. Hydrogen (H+), ferrous (Fe2+) and aluminium (Al) ions are the dominant acid cations involved. When drainage water is mixed

F. J Cook; W Hicks; E. A Gardner; G. D Carlin; D. W Froggatt

2000-01-01

314

CONVERSION OF OLEIC ACID TO BRANCHED-CHAIN FATTY ACIDS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Oleic acid and linoleic acid are the most abundant fatty acids of cottonseed oil. As part of a project to develop new value-added industrial applications for cottonseed oil (such as biodiesel, fuel additives, and lubricants), studies were conducted in the synthetic conversion of oleic acid to branc...

315

Kidney amino acid transport.  

PubMed

Near complete reabsorption of filtered amino acids is a main specialized transport function of the kidney proximal tubule. This evolutionary conserved task is carried out by a subset of luminal and basolateral transporters that together form the transcellular amino acid transport machinery similar to that of small intestine. A number of other amino acid transporters expressed in the basolateral membrane of proximal kidney tubule cells subserve either specialized metabolic functions, such as the production of ammonium, or are part of the cellular housekeeping equipment. A new finding is that the luminal Na(+)-dependent neutral amino acid transporters of the SLC6 family require an associated protein for their surface expression as shown for the Hartnup transporter B(0)AT1 (SLC6A19) and suggested for the L: -proline transporter SIT1 (IMINO(B), SLC6A20) and for B(0)AT3 (XT2, SLC6A18). This accessory subunit called collectrin (TMEM27) is homologous to the transmembrane anchor region of the renin-angiotensin system enzyme ACE2 that we have shown to function in small intestine as associated subunit of the luminal SLC6 transporters B(0)AT1 and SIT1. Some mutations of B(0)AT1 differentially interact with these accessory subunits, providing an explanation for differential intestinal phenotypes among Hartnup patients. The basolateral efflux of numerous amino acids from kidney tubular cells is mediated by heteromeric amino acid transporters that function as obligatory exchangers. Thus, other transporters within the same membrane need to mediate the net efflux of exchange substrates, controlling thereby the net basolateral amino transport and thus the intracellular amino acid concentration. PMID:19184091

Verrey, François; Singer, Dustin; Ramadan, Tamara; Vuille-dit-Bille, Raphael N; Mariotta, Luca; Camargo, Simone M R

2009-01-28

316

Transformation of some hydroxy amino acids to other amino acids.  

PubMed

It has been observed that beta-hydroxy-alpha-amino acids are transformed into other amino acids, when heated in dilute solutions with phosphorous acid, phosphoric acid or their ammonium salts. It has been shown that as in the case of previously reported glycine-aldehyde reactions, glycine also reacts with acetone to give beta-hydroxyvaline under prebiologically feasible conditions. It is suggested, therefore, that the formation of beta-hydroxy-alpha-amino acids and their transformation to other amino acids may have been a pathway for the synthesis of amino acids under primitive earth conditions. PMID:1208100

Choughuley, A S; Subbaraman, A S; Kazi, Z A; Chadha, M S

1975-10-01

317

Adsorption of humic acid on acid-activated Greek bentonite  

Microsoft Academic Search

The adsorption of humic acid on bentonite from Milos Island (Greece) acid-treated with dilute H2SO4 solutions over a concentration range between 0.25 and 13M has been studied. Bentonite activated with 3M sulfuric acid (AAS) showed a higher efficiency in removing humic acid from aqueous solutions and was selected for further investigation. The specific surface area of acid-activated bentonite was estimated

Danae Doulia; Ch. Leodopoulos; K. Gimouhopoulos; F. Rigas

2009-01-01

318

Analysis of Bile Acids  

NASA Astrophysics Data System (ADS)

Bile acids constitute a large family of steroids in vertebrates, normally formed from cholesterol and carrying a carboxyl group in a side-chain of variable length. Bile alcohols, also formed from cholesterol, have similar structures as bile acids, except for the absence of a carboxyl group in the steroid skeleton. The conversion of cholesterol to bile acids and/or bile alcohols is of major importance for maintenance of cholesterol homeostasis, both from quantitative and regulatory points of view (Chiang, 2004; Kalaany and Mangelsdorf, 2006; Moore, Kato, Xie, et al., 2006; Scotti, Gilardi, Godio, et al., 2007). Appropriately conjugated bile acids and bile alcohols (also referred to as bile salts) are secreted in bile and serve vital functions in the absorption of lipids and lipid-soluble compounds (Hofmann, 2007). Reliable analytical methods are required for studies of the functions and pathophysiological importance of the variety of bile acids and bile alcohols present in living organisms. When combined with genetic and proteomic studies, analysis of these small molecules (in today's terminology: metabolomics, steroidomics, sterolomics, cholanoidomics, etc.) will lead to a deeper understanding of the integrated metabolic processes in lipid metabolism.

Sjövall, Jan; Griffiths, William J.; Setchell, Kenneth D. R.; Mano, Nariyasu; Goto, Junichi

319

Optical high acidity sensor  

DOEpatents

An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber. 10 figs.

Jorgensen, B.S.; Nekimken, H.L.; Carey, W.P.; O`Rourke, P.E.

1997-07-22

320

78 FR 20029 - Castor Oil, Polymer With Adipic Acid, Linoleic Acid, Oleic Acid and Ricinoleic Acid; Tolerance...  

Federal Register 2010, 2011, 2012, 2013

...EPA-HQ-OPP-2013-0057; FRL-9381-2] Castor Oil, Polymer With Adipic Acid, Linoleic Acid, Oleic...tolerance for residues of castor oil, polymer with adipic acid, linoleic acid, oleic...ingredient in a pesticide formulation. Advance Polymer Technology submitted a petition to...

2013-04-03

321

Oleanane acid from Myrica cerifera.  

PubMed

From the twigs of Myrica cerifera L. (Myricaceae), a new oleanane triterpenic acid named myrica acid was isolated along with myricalactone and several other known constituents. The structure of the acid was determined as 3beta-hydroxy-1-oxoolean-11,13(18)-dien-28-oic acid on the basis of chemical and spectral evidence. PMID:11045444

Nagai, M; Sakurai, N; Yumoto, N; Nagumo, S; Seo, S

2000-10-01

322

Ursodeoxycholic acid, 7-ketolithocholic acid, and chenodeoxycholic acid are primary bile acids of the nutria (Myocastor coypus).  

PubMed

Because ursodeoxycholic and chenodeoxycholic acids are interconverted in humans via 7-ketolithocholic acid, bile acid metabolism was studied in the nutria (Myocastor coypus), the bile of which is known to contain these three bile acids. Relative concentrations of ursodeoxycholic (37% +/- 20%), 7-ketolithocholic (33% +/- 17%), and chenodeoxycholic (17% +/- 9%) acids in gallbladder bile were unchanged by 5-20 h of complete biliary diversion (n = 7). Injection of either [14C]cholesterol, [14C]ursodeoxycholic, [14C]7-ketolithocholic acid, or a mixture of [7 beta-3H]chenodeoxycholic acid and [14C]chenodeoxycholic acid into bile fistula nutria demonstrated that all three bile acids can be synthesized hepatically from cholesterol, that they are interconverted sparingly (2%-5%) by the liver, but that 7-ketolithocholic acid is an intermediate in the hepatic transformation of chenodeoxycholic acid to ursodeoxycholic acid. An animal that had been fed antibiotics showed an unusually elevated concentration of ursodeoxycholic acid in gallbladder and hepatic bile, suggesting that bacterial transformation of ursodeoxycholic acid in the intestine may be a source of some biliary chenodeoxycholic acid and 7-ketolithocholic acid. PMID:3943698

Tint, G S; Bullock, J; Batta, A K; Shefer, S; Salen, G

1986-03-01

323

Atmospheric Dust and Acid Rain  

Microsoft Academic Search

Why is acid rain still an environmental problem in Europe and North America despite antipollution reforms? The answer really is blowing in the wind: atmospheric dust. These airborne particles can help neutralize the acids falling on forests, but dust levels are unusually low these days. In the air dust particles can neutralize acid rain. What can we do about acid

Lars O. Hedin; Gene E. Likens

1996-01-01

324

BIOSYNTHESIS OF TETRAHYDROFURANYL FATTY ACIDS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Clavibacter sp. ALA2 converts linoleic acid into many novel oxygenated products including hydroxy fatty acids and tetrahydrofuranyl unsaturated fatty acids (THFAs). One of them was tentatively identified by GC/MS as 12,13,16-trihydroxy-9(z)-octadecenoic acid (12,13,16-THOA, Hou et al. J Am. Oil Che...

325

Acid rain: a background report  

Microsoft Academic Search

This Staff Brief was prepared for the Wisconsin Legislative Council's Special Committee on Acid Rain to provide an introduction to the issue of acid rain. It is divided into four parts. Part I provides an overview on the controversies surrounding the measurement, formation and effects of acid rain. As described in Part I, the term acid rain is used to

L. Glustrom; J. Stolzenberg

1982-01-01

326

Diversity of bacterial polyhydroxyalkanoic acids  

Microsoft Academic Search

An overview is provided on the diversity of biosynthetic polyhydroxyalkanoic acids, and all hitherto known constituents of these microbial storage compounds are listed. The occurrence of 91 different hydroxyalkanoic acids reflects the low substrate specificity of polyhydroxyalkanoic acid synthases which are the key enzymes of polyhydroxyalkanoic acid biosynthesis. In addition, the importance of bacterial anabolism and catabolism, which provide the

Alexander Steinbüchel; Henry E. Valentin

1995-01-01

327

Method for acidizing siliceous formations  

SciTech Connect

A method is described for treating a subterranean formation surrounding a wellbore which comprises injecting into the formation an aqueous acidizing solution. The aqueous acidizing solution contains hydrofluoric acid and excess fluoride. The excess fluoride is present in an amount greater than the amount of fluoride stoichiometrically required to form hydrofluoric acid, and thereafter fluids are produced from the wellbore.

Lamb, W.J.; Kunze, K.R.

1987-03-10

328

Corrosion inhibitors used in acidizing  

Microsoft Academic Search

The history of the development of oil well acidizing and acid corrosion inhibitors used by this industry is reviewed. As deeper and hotter wells were drilled, stimulation acids were exposed to hotter conditions and the organic inhibitors required intensifiers. High-temperature acid corrosion inhibitors are also discussed.

Cizek

1994-01-01

329

Thiol modified mycolic acids.  

PubMed

Patient serum antibodies to mycolic acids have the potential to be surrogate markers of active tuberculosis (TB) when they can be distinguished from the ubiquitously present cross-reactive antibodies to cholesterol. Mycolic acids are known to interact more strongly with antibodies present in the serum of patients with active TB than in patients with latent TB or no TB. Examples of single stereoisomers of mycolic acids with chain lengths corresponding to major homologues of those present in Mycobacterium tuberculosis have now been synthesised with a sulfur substituent on the terminal position of the ?-chain; initial studies have established that one of these binds to a gold electrode surface, offering the potential to develop second generation sensors for diagnostic patient antibody detection. PMID:23603063

Balogun, Mohammed O; Huws, Enlli H; Sirhan, Muthana M; Saleh, Ahmed D; Al Dulayymi, Juma'a R; Pilcher, Lynne; Verschoor, Jan A; Baird, Mark S

2013-04-18

330

Acid rain in Asia  

NASA Astrophysics Data System (ADS)

Acid rain has been an issue of great concern in North America and Europe during the past several decades. However, due to the passage of a number of recent regulations, most notably the Clean Air Act in the United States in 1990, there is an emerging perception that the problem in these Western nations is nearing solution. The situation in the developing world, particularly in Asia, is much bleaker. Given the policies of many Asian nations to achieve levels of development comparable with the industrialized world—which necessitate a significant expansion of energy consumption (most derived from indigenous coal reserves)—the potential for the formation of, and damage from, acid deposition in these developing countries is very high. This article delineates and assesses the emissions patterns, meteorology, physical geology, and biological and cultural resources present in various Asian nations. Based on this analysis and the risk factors to acidification, it is concluded that a number of areas in Asia are currently vulnerable to acid rain. These regions include Japan, North and South Korea, southern China, and the mountainous portions of Southeast Asia and southwestern India. Furthermore, with accelerated development (and its attendant increase in energy use and production of emissions of acid deposition precursors) in many nations of Asia, it is likely that other regions will also be affected by acidification in the near future. Based on the results of this overview, it is clear that acid deposition has significant potential to impact the Asian region. However, empirical evidence is urgently needed to confirm this and to provide early warning of increases in the magnitude and spread of acid deposition and its effects throughout this part of the world.

Bhatti, Neeloo; Streets, David G.; Foell, Wesley K.

1992-07-01

331

Molecular Structure of Citric Acid  

NSDL National Science Digital Library

Citric Acid was first isolated in 1734 by Carl Wilhelm Scheele. Citric acid is found in many fruits, in particular lemons, grapefruit, and oranges. Several types of bacteria and fungi are also known to produce citric acid. In fact, the fungus Aspergillus niger produces the vast majority of citric acid, which is used in almost all carbonated sodas. Additionally, citric acid is also used to clean stainless steel.

2002-08-13

332

Eucomic acid methanol monosolvate  

PubMed Central

In the crystal structure of the title compound [systematic name: 2-hy­droxy-2-(4-hy­droxy­benz­yl)butane­dioic acid methanol monosolvate], C11H12O6·CH3OH, the dihedral angles between the planes of the carboxyl groups and the benzene ring are 51.23?(9) and 87.97?(9)°. Inter­molecular O—H?O hydrogen-bonding inter­actions involving the hy­droxy and carb­oxy­lic acid groups and the methanol solvent mol­ecule give a three-dimensional structure.

Li, Guo-Qiang; Li, Yao-Lan; Wang, Guo-Cai; Liang, Zhi-Hong; Jiang, Ren-Wang

2011-01-01

333

Polyvalent Nucleic Acid Nanostructures  

PubMed Central

Polyvalent oligonucleotide-nanoparticle conjugates possess several unique emergent properties including enhanced cellular uptake, high antisense bioactivity, and nuclease resistance, which hypothetically originate from the dense packing and orientation of oligonucleotides on the surface of the nanoparticle. In this communication, we describe a new class of polyvalent nucleic acid nanostructures (PNANs), which comprise only crosslinked and oriented nucleic acids. We demonstrate that these particles are capable of effecting high cellular uptake and gene regulation without the need of a cationic polymer co-carrier. The PNANs also exhibit cooperative binding behavior and nuclease resistance properties.

Cutler, Joshua I.; Zhang, Ke; Zheng, Dan; Auyeung, Evelyn; Prigodich, Andrew E.

2011-01-01

334

Acid rain information clearinghouse  

SciTech Connect

Twenty-one research institutions, environmental organizations, trade associations and government agencies from the United States and Canada are co-sponsoring Acid Rain: The Relationship Between Sources and Receptors, a conference to be held December 3-4, 1986 at the Sheraton National Hotel in Arlington, Virginia. The conference, designed for a nontechnical audience as well as specialists in acid rain research, will cover the nature and scope of scientific understanding and research programs, identify areas of consensus and disagreement, and assess policy options in the light of current understanding. A special session on December 3 will address the legal aspects of source-receptor relationships.

Not Available

1986-11-01

335

Acid rain revisited  

SciTech Connect

This article reviews calculations of the estimates reported in this Newletter in 1983 on the contributions of nitric and sulfuric acids to deposition that may originate with motor vehicles. Previous estimates can now be updated, based on the recently released 1985 emissions inventory that was compiled by the National Acid Precipitation Assessment Program (NAPAP). This inventory relied in turn on the US Environmental Protection Agency's National emissions Data System (NEDS), the 1985 version of which is the latest containing both point source and area source information in sufficient detail to be useful for this purpose.

Not Available

1990-06-01

336

The second acidic constant of salicylic acid.  

PubMed

The second dissociation constant of salicylic acid (H2L) has been determined, at 25 degrees C, in NaCl ionic media by UV spectrophotometric measurements. The investigated ionic strength values were 0.16, 0.25, 0.50, 1.0, 2.0 and 3.0 M. The protolysis constants calculated at the different ionic strengths yielded, with the Specific Interaction Theory, the infinite dilution constant, log beta1(0) = 13.62 +/- 0.03, for the equilibrium L2- + H+ <==> HL-. The interaction coefficient between Na+ and L2-, b(Na+, L2-) = 0.02 +/- 0.07, has been also calculated. PMID:16235788

Porto, Raffaella; De Tommaso, Gaetano; Furia, Emilia

337

The Acid-Base Titration of a Very Weak Acid: Boric Acid  

ERIC Educational Resources Information Center

|A laboratory experiment based on the titration of boric acid with strong base in the presence of d-mannitol is described. Boric acid is a very weak acid and direct titration with NaOH is not possible. An auxiliary reagent that contributes to the release of protons in a known stoichiometry facilitates the acid-base titration. Students obtain the…

Celeste, M.; Azevedo, C.; Cavaleiro, Ana M. V.

2012-01-01

338

Acid neutralizing capacity, alkalinity, and acid-base status of natural waters containing organic acids  

Microsoft Academic Search

The terms acid neutralizing capacity (ANC) and alkalinity (Alk) are extensively employed in the characterization of natural waters, including soft circumneutral or acidic waters. However, in the presence of organic acids, ANC measurements are inconsistent with many conceptual definitions of ANC or Alk and do not provide an adequate characterization of the acid-base chemistry of water. Knowledge of Gran ANC

Harold F. Hemond

1990-01-01

339

Oxalic acid excretion after intravenous ascorbic acid administration  

PubMed Central

Ascorbic acid is frequently administered intravenously by alternative health practitioners and, occasionally, by mainstream physicians. Intravenous administration can greatly increase the amount of ascorbic acid that reaches the circulation, potentially increasing the risk of oxalate crystallization in the urinary space. To investigate this possibility, we developed gas chromatography mass spectrometry methodology and sampling and storage procedures for oxalic acid analysis without interference from ascorbic acid and measured urinary oxalic acid excretion in people administered intravenous ascorbic acid in doses ranging from 0.2 to 1.5 g/kg body weight. In vitro oxidation of ascorbic acid to oxalic acid did not occur when urine samples were brought immediately to pH less than 2 and stored at –30°C within 6 hours. Even very high ascorbic acid concentrations did not interfere with the analysis when oxalic acid extraction was carried out at pH 1. As measured during and over the 6 hours after ascorbic acid infusions, urinary oxalic acid excretion increased with increasing doses, reaching approximately 80 mg at a dose of approximately 100 g. We conclude that, when studied using correct procedures for sample handling, storage, and analysis, less than 0.5% of a very large intravenous dose of ascorbic acid is recovered as urinary oxalic acid in people with normal renal function.

Robitaille, Line; Mamer, Orval A.; Miller, Wilson H.; Levine, Mark; Assouline, Sarit; Melnychuk, David; Rousseau, Caroline; Hoffer, L. John

2012-01-01

340

Prediction of effective acid penetration and acid volume for matrix acidizing treatments in naturally fractured carbonates  

SciTech Connect

This paper discusses a new method and a corresponding computer model developed to investigate matrix acidizing in naturally fractured carbonates. With this method, the effective acid penetration distance and acid volume needed for acid treatments in naturally fractured carbonates can be predicted. The new model simulates acid flowing in the natural fracture network and the acid/rock reaction. During the simulation, the model considers the influence of formation temperature, reaction heat, and common ion effect on acid penetration. A set of graphs showing the relationship between acid penetration and the acid volume needed in different formations was developed from numerical simulation results. From these plots, the acid volume that should be used to remove the formation damage can be determined easily when the formation temperature and the damage radius are known or can be estimated.

Xiong, H. (S.A. Holditch and Associates, Inc., College Station, TX (United States))

1994-08-01

341

[Studies on interaction of acid-treated nanotube titanic acid and amino acids].  

PubMed

Nanotube titanic acid (NTA) has distinct optical and electrical character, and has photocatalysis character. In accordance with these qualities, NTA was treated with acid so as to enhance its surface activity. Surface structures and surface groups of acid-treated NTA were characterized and analyzed by Transmission Electron Microscope (TEM) and Fourier Transform Infrared Spectrometry (FT-IR). The interaction between acid-treated NTA and amino acids was investigated. Analysis results showed that the lengths of acid-treated NTA became obviously shorter. The diameters of nanotube bundles did not change obviously with acid-treating. Meanwhile, the surface of acid-treated NTA was cross-linked with carboxyl or esterfunction. In addition, acid-treated NTA can catch amino acid residues easily, and then form close combination. PMID:20649031

Zhang, Huqin; Chen, Xuemei; Jin, Zhensheng; Liao, Guangxi; Wu, Xiaoming; Du, Jianqiang; Cao, Xiang

2010-06-01

342

Alkyl phosphonic acids and sulfonic acids in the Murchison meteorite  

NASA Astrophysics Data System (ADS)

Homologous series of alkyl phosphonic acids and alkyl sulfonic acids, along with inorganic orthophosphate and sulfate, are identified in water extracts of the Murchison meteorite after conversion to their t-butyl dimethylsilyl derivatives. The methyl, ethyl, propyl, and butyl compounds are observed in both series. Five of the eight possible alkyl phosphonic acids and seven of the eight possible alkyl sulfonic acids through C4 are identified. Abundances decrease with increasing carbon number as observed of other homologous series indigenous to Murchison. Concentrations range downward from approximately 380 nmol/gram in the alkyl sulfonic acid series, and from 9 nmol/gram in the alkyl phosphonic acid series.

Cooper, George W.; Onwo, Wilfred M.; Cronin, John R.

1992-11-01

343

Lysergic Acid Diethylamide: Radioimmunoassay  

Microsoft Academic Search

A radioimmunoassay for d-lysergic acid diethylamide (LSD) is described. Antibodies to LSD were obtained by immunizing rabbits with a conjugate of LSD and human serum albumin. The specificity of the antibody was shown by competitive binding studies. The method has been used to detect the presence of LSD in human urines. Picogram amounts can be measured by this assay.

Alison Taunton-Rigby; Stephanie E. Sher; Paul R. Kelley

1973-01-01

344

Acidification and Acid Rain  

Microsoft Academic Search

Air pollution by acids has been known as a problem for centuries (Ducros, 1845; Smith, 1872; Camuffo, 1992; Brimblecombe, 1992). Only in the mid-1900s did it become clear that it was a problem for more than just industrially developed areas, and that precipitation quality can affect aquatic resources ( Gorham, 1955). The last three decades of the twentieth century saw

S. A. Norton

2003-01-01

345

Basically Acidic Ink  

NSDL National Science Digital Library

Students hypothesize whether vinegar and ammonia-based glass cleaner are acids or bases. They create designs on index cards using these substances as invisible inks. After the index cards have dried, they apply red cabbage juice as an indicator to reveal the designs.

University Of Houston

346

Beyond acid rain  

Microsoft Academic Search

This paper discussed the effects of the interactions of soluble oxidants and organic toxins with sulfur dioxide and nitrogen dioxide. It suggested that these chemical reactions in the atmosphere produced a more potent acid rain which was harmful not only because it had a low pH but because it contained oxidants and organic toxins which were harmful to surface vegetation

J. S. Gaffney; G. E. Streit; W. D. Spall; J. H. Hall

1987-01-01

347

Gallic acid pyridine monosolvate  

PubMed Central

In the title compound (systenatic name: 3,4,5-trihy­droxy­benzoic acid pyridine monosolvate), C5H5N·C7H6O5, the gallic acid mol­ecule is essentially planar (r.m.s deviation = 0.0766?Å for non-H atoms) and is linked to the pyridine mol­ecule by an O—H?N hydrogen bond. An intra­molecular O—H?O hydrogen bond occurs in the gallic acid mol­ecule. The gallic acid and pyridine mean planes make a dihedral angle 12.6?(3)°. Inter­molecular O—H?O and O—H?N hydrogen bonding involving the hy­droxy and carboxyl groups and the pyridine mol­ecule, and ?–? inter­actions between inversion-related pyridines [centroid–centroid distance = 3.459?(6)?Å] and between pyridine and benzene rings [centroid–centroid distance = 3.548?(6)?Å], lead to a three-dimensional network in the crystal.

Dong, Fu-Yue; Wu, Jie; Tian, Hai-Yan; Ye, Qing-Mei; Jiang, Ren-Wang

2011-01-01

348

Federal Acid Rain Games  

Microsoft Academic Search

Federal environmental policy, designed to control acid rain, is shaped after the hierarchy of the system, and is controlled simultaneously by regional and central governments. Each governmental level controls one of two policy instruments: pollution abatement production and pollution tax. In a two-stage game where regional governments are Stackelberg leaders and control pollution taxes, the subgame perfect equilibrium is socially

Arthur J. Caplan; Emilson C. D. Silva

1999-01-01

349

Acid rain bibliography  

SciTech Connect

This bibliography identifies 900 citations on various aspects of Acid Rain, covering published bibliographies, books, reports, conference and symposium proceedings, audio visual materials, pamphlets and newsletters. It includes five sections: citations index (complete record of author, title, source, order number); KWIC index; title index; author index; and source index. 900 references.

Sayers, C.S.

1983-09-01

350

Acid rain in Asia  

Microsoft Academic Search

Acid rain has been an issue of great concern in North America and Europe during the past several decades. However, due to the passage of a number of recent regulations, most notably the Clean Air Act in the United States in 1990, there is an emerging perception that the problem in these Western nations is nearing solution. The situation in

N. Bhatti; D. G. Streets; W. K. Foell

2009-01-01

351

Acid rain in Asia  

Microsoft Academic Search

Acid rain has been an issue of widespread concern in North America and Europe for more than fifteen years. However, there is an emerging feeling that the problem in Europe and North America is nearing solution, largely as a result of existing and newly enacted legislation, decreased energy use due to conservation and efficiency improvements, and\\/or trends in energy policy

N. Bhatti; D. G. Streets; W. K. Foell

1991-01-01

352

Immunostimulatory Nucleic Acid Molecules.  

National Technical Information Service (NTIS)

Nucleic acids containing unmethylated CpG dinucleotides and therapeutic utilities based on their ability to stimulate an immune response and to redirect a Th2 response to a Th1 response in a subject are disclosed. Methods for treating atopic diseases, inc...

A. D. Steinberg A. M. Krieg D. Klinman J. Kline

2005-01-01

353

Optimize acid gas removal  

Microsoft Academic Search

Innovative design of physical solvent plants for acid gas removal can materially reduce both installation and operating costs. A review of the design considerations for one physical solvent process (Selexol) points to numerous arrangements for potential improvement. These are evaluated for a specific case in four combinations that identify an optimum for the case in question but, more importantly, illustrate

D. M. Nicholas; J. T. Wilkins

1983-01-01

354

Fumaric acid esters  

Microsoft Academic Search

Several clinical studies have shown that systemic therapy with fumaric acid esters (FAEs) in patients with moderate to severe psoriasis is effective and has a good long-term safety profile. For therapeutic use, tablets with a defined mixture of FAEs (dimethylfumarate [DMF] and three different salts of monoethylfumarate) are registered in Germany. There is evidence that DMF is the most essential

Martin Rostami Yazdi; Ulrich Mrowietz

2008-01-01

355

Water surface is acidic  

PubMed Central

Water autoionization reaction 2H2O ? H3O? + OH? is a textbook process of basic importance, resulting in pH = 7 for pure water. However, pH of pure water surface is shown to be significantly lower, the reduction being caused by proton stabilization at the surface. The evidence presented here includes ab initio and classical molecular dynamics simulations of water slabs with solvated H3O+ and OH? ions, density functional studies of (H2O)48H+ clusters, and spectroscopic isotopic-exchange data for D2O substitutional impurities at the surface and in the interior of ice nanocrystals. Because H3O+ does, but OH? does not, display preference for surface sites, the H2O surface is predicted to be acidic with pH < 4.8. For similar reasons, the strength of some weak acids, such as carbonic acid, is expected to increase at the surface. Enhanced surface acidity can have a significant impact on aqueous surface chemistry, e.g., in the atmosphere.

Buch, Victoria; Milet, Anne; Vacha, Robert; Jungwirth, Pavel; Devlin, J. Paul

2007-01-01

356

Acid Mine Drainage Remediation  

NSDL National Science Digital Library

In this video, an environmental technologist visits an abandoned coal mine in Kentucky to talk about how a remediation system (a series of settling ponds and treatment cells) is neutralizing the acid drainage flowing from the mine and keeping it from damaging a creek downstream.

Ket

2011-01-11

357

Spermatotoxicity of dichloroacetic acid  

EPA Science Inventory

The testicular toxicity of dichloroacetic acid (DCA), a disinfection byproduct of drinking water, was evaluated in adult male rats given both single and multiple (up to 14 d) oral doses. Delayed spermiation and altered resorption of residual bodies were observed in rats given sin...

358

Bile acid coenzyme A: amino acid N-acyltransferase in the amino acid conjugation of bile acids.  

PubMed

Bile acids are converted to their glycine and taurine N-acyl amidates by enzymes in the liver in a two-step process. This increases their aqueous solubility, particularly in the acidic environment of the upper part of the small intestine. Bile acid coenzyme A (CoA) thioesters synthesized by bile acid CoA ligase (see Shonsey et al., 2005) are substrates of bile acid CoA:amino acid N-acyltransferases (BAT) in the formation of bile acid N-acyl amidates. This chapter describes the methods used to purify BAT from human liver, to isolate and clone cDNAs encoding BAT from human, mouse, and rat liver cDNA libraries, the expression of BAT, the assays used to measure BAT activity, and the chemical syntheses of bile acid N-acylamidates. In addition, an enzyme that catalyzes further metabolism of glycine-conjugated bile acids is described. PMID:16399361

Shonsey, Erin M; Sfakianos, Mindan; Johnson, Michelle; He, Dongning; Falany, Charles N; Falany, Josie; Merkler, David J; Barnes, Stephen

2005-01-01

359

Tranexamic acid and thrombosis.  

PubMed

Tranexamic acid is an antifibrinolytic drug. It therefore reduces bleeding but, in certain situations, it may expose patients to a risk of thrombosis. It is used for the treatment of various types of bleeding, including menorrhagia, haematuria, certain surgical procedures and trauma. Its harm-benefit balance is favourable in certain situations associated with serious bleeding.The harm-benefit balance is different in minor bleeding: the expected benefits are smaller because the condition is not serious, and the risk of thromboembolism may be higher without the haemodilution associated with severe bleeding. Various drug regulatory agencies have received reports of thrombotic events attributed to tranexamic acid. In a case-control study using data from the British General Practice Research Database, women taking tranexamic acid had a 3-fold higher risk of developing deep vein thrombosis. There was a wide 95% confidence interval, ranging from 0.7 to 15.8; thus, a major increase in the risk of thrombosis cannot be ruled out. Only one comparative randomised trial assessed thrombotic events in 53 women receiving tranexamic acid for menorrhagia; too few patients were studied to determine the risk. Clinical trials conducted in serious haemorrhage or in patients undergoing surgery with a high risk of bleeding have not shown an increased risk of thrombosis with tranexamic acid. In practice, as of early 2013, the harm-benefit balance of tranexamic acidis favourable in severe traumatic bleeding. But when bleeding is not life-threatening, the thrombotic risk is too poorly documented to justify exposing patients to a plausible and inadequately evaluated risk. PMID:23951593

2013-07-01

360

Specific bile acids inhibit hepatic fatty acid uptake  

PubMed Central

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

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

2012-01-01

361

Effects of acidic precipitation and acidity on soil microbial processes  

SciTech Connect

Effects of oil acidity on microbial decomposition of organic matter and transformation of nitrogen in an acid forest soil were investigated. In the oak-leaf-amended pH-adjusted acid soils, CO/sub 2/ production in 14- and 150-day preincubated samples decreased by about 6 and 37%, respectively. In the control (unamended) acidified soils, reductions in CO/sub 2/ production of 14% in 14-day preincubated samples and 52% in 150-day samples were observed. Ammonia formation in the pH-adjusted acid soil was about 50% less than in the naturally acid soil. Increased rates of ammonification and nitrification were observed in the pH-adjusted neutral soil. Little autotrophic and heterotrophic nitrifying activity was detected in naturally acid and acidified forest soils. The rate of denitrification was rather slow in acid soils, and at greater acidities N/sub 2/O was the predominant end product. The abundance of nitrogen-fixing free-living bacteria was very low in acidic and acidified forest soils, and nitrogen gains by asymbiotic bacterial fixation in an acid forest ecosystem may be insignificant. These results suggest that further acidification of acid forest soils by addition of sulfuric acid or by acid precipitation may lead to significant reductions in the leaf litter decomposition, ammonification, nitrification, and denitrification and thus reduce nutrient recycling in the forest ecosystem.

Francis, A.J.

1981-01-01

362

Measurement of ascorbic acid and dehydroascorbic acid in biological samples.  

PubMed

Ascorbic acid and dehydroascorbic acid are commonly used biomarkers of oxidative stress in a variety of experimental models. However, the accurate measurement of these labile compounds remains a challenge both in terms of sample collection and analysis. Determination of dehydroascorbic acid most commonly involves indirect measurement. The concentration is calculated by subtraction of the measured ascorbic acid concentration from that of total ascorbic acid analyzed after reduction of the dehydroascorbic acid present; a method referred to as the subtraction method. Consequently, successful determination of dehydroascorbic acid is dependent upon proper sample handling, quantitative reduction of the compound, and accurate quantification of both ascorbic acid and total ascorbic acid. The unit presents a detailed introduction to ascorbate analysis in biological samples and discusses common problems and pitfalls. The analytical method described is based on reversed-phase HPLC with coloumetric detection. This method includes co-analysis of isoascorbic acid and uric acid. Where applicable, uric acid can conveniently be used as an endogenous intrasample standard that significantly improves the accuracy of the subsequent dehydroascorbic acid calculation. PMID:20954159

Lykkesfeldt, Jens

2002-08-01

363

Radioenzymatic assay for quinolinic acid  

SciTech Connect

A new and rapid method for the determination of the excitotoxic tryptophan metabolite quinolinic acid is based on its enzymatic conversion to nicotinic acid mononucleotide and, in a second step utilizing (/sup 3/H)ATP, further to (/sup 3/H) deamido-NAD. Specificity of the assay is assured by using a highly purified preparation of the specific quinolinic acid-catabolizing enzyme, quinolinic acid phosphoribosyltransferase, in the initial step. The limit of sensitivity was found to be 2.5 pmol of quinolinic acid, sufficient to conveniently determine quinolinic acid levels in small volumes of human urine and blood plasma.

Foster, A.C.; Okuno, E.; Brougher, D.S.; Schwarcz, R.

1986-10-01

364

Linoleic acid requirement of rats fed trans fatty acids  

Microsoft Academic Search

The amount of linoleic acid required to prevent undesirable effects of C18trans fatty acids was investigated. In a first experiment, six groups of rats were fed diets with a high content oftrans fatty acids (20% of energy [en%]), and increasing amounts of linoleic acid (0.4 to 7.1 en%). In a second experiment, four\\u000a groups of rats were fed diets designed

J. L. Zevenbergen; U. M. T. Houtsmuller; J. J. Gottenbos

1988-01-01

365

Do trans Fatty Acids Impair Linoleic Acid Metabolism in Children?  

Microsoft Academic Search

Trans isomeric fatty acids disturb themetabolism of essential polyunsaturated fatty acids in animals and in premature infants. We assessed whether similar effects may also occur in healthy children. Plasma phospholipid fatty acid composition was analysed in 53 apparently healthy children aged 1-15 years (mean 7.5 years). Trans fatty acids were found in all samples and contributed 1.78 ± 0.10% (w\\/w,

Tamås Decsi; Berthold Koletzko

1995-01-01

366

Thiobarbituric Acid Spray Reagent for Deoxy Sugars and Sialic Acids  

Microsoft Academic Search

RECENTLY, new sensitive assays have been reported for deoxy sugars1, 2-keto,3-deoxy sugar acids2-4, and sialic acids5,6. In these assays, the products of periodate oxidation, malonaldehyde from deoxy sugars and beta-formylpyruvic acid from the latter two groups of compounds, are coupled with 2-thiobarbituric acid to produce a bright red chromophore. I wish to report an adaptation of these methods for spraying

Leonard Warren

1960-01-01

367

Effect of phenolic acids on glucose and organic acid metabolism by lactic acid bacteria from wine.  

PubMed

The influence of phenolic (p-coumaric, caffeic, ferulic, gallic and protocatechuic) acids on glucose and organic acid metabolism by two strains of wine lactic acid bacteria (Oenococcus oeni VF and Lactobacillus hilgardii 5) was investigated. Cultures were grown in modified MRS medium supplemented with different phenolic acids. Cellular growth was monitored and metabolite concentrations were determined by HPLC-RI. Despite the strong inhibitory effect of most tested phenolic acids on the growth of O. oeni VF, the malolactic activity of this strain was not considerably affected by these compounds. While less affected in its growth, the capacity of L. hilgardii 5 to degrade malic acid was clearly diminished. Except for gallic acid, the addition of phenolic acids delayed the metabolism of glucose and citric acid in both strains tested. It was also found that the presence of hydroxycinnamic acids (p-coumaric, caffeic and ferulic) increased the yield of lactic and acetic acid production from glucose by O. oeni VF and not by L. hilgardii 5. The results show that important oenological characteristics of wine lactic acid bacteria, such as the malolactic activity and the production of volatile organic acids, may be differently affected by the presence of phenolic acids, depending on the bacterial species or strain. PMID:19376463

Campos, Francisco M; Figueiredo, Ana R; Hogg, Tim A; Couto, José A

2009-02-07

368

A Variation in Acid-Catalyzed Isomerization of Abietadienoic Acids  

Microsoft Academic Search

Heating the individual common abietadienoic acid methyl esters with p-toluene sulfonic acid in chloroform led to the formation of methyl abietadienoates other than the equilibrium mixture of methyl abietate, palustrate, and neoabietate that is usually formed by acid-catalyzed isomerization. Of these other methyl abietadienoates, the three principal constituents comprised 10%, 4% and 2% of the monomers; these compounds were isolated

Duane F. Zinkel

1991-01-01

369

College Chemistry Students' Mental Models of Acids and Acid Strength  

ERIC Educational Resources Information Center

|The central goal of this study was to characterize the mental models of acids and acid strength expressed by advanced college chemistry students when engaged in prediction, explanation, and justification tasks that asked them to rank chemical compounds based on their relative acid strength. For that purpose we completed a qualitative research…

McClary, LaKeisha; Talanquer, Vicente

2011-01-01

370

NAPAP (National Acid Precipitation Assessment Program) results on acid rain  

SciTech Connect

The National Acid Precipitation Assessment Program (NAPAP) was mandated by Congress in 1980 to study the effects of acid rain. The results of 10 years of research on the effect of acid deposition and ozone on forests, particularly high elevation spruce and fir, southern pines, eastern hardwoods and western conifers, will be published this year.

Not Available

1990-06-01

371

Acid Earth--The Global Threat of Acid Pollution.  

ERIC Educational Resources Information Center

|Acid pollution is a major international problem, but the debate it has elicited has often clouded the distinction between myth and facts. This publication attempts to concerning the acid pollution situation. This publication attempts to identify available facts. It is the first global review of the problem of acid pollution and the first to…

McCormick, John

372

College Chemistry Students' Mental Models of Acids and Acid Strength  

ERIC Educational Resources Information Center

The central goal of this study was to characterize the mental models of acids and acid strength expressed by advanced college chemistry students when engaged in prediction, explanation, and justification tasks that asked them to rank chemical compounds based on their relative acid strength. For that purpose we completed a qualitative research…

McClary, LaKeisha; Talanquer, Vicente

2011-01-01

373

Acid Earth--The Global Threat of Acid Pollution.  

ERIC Educational Resources Information Center

Acid pollution is a major international problem, but the debate it has elicited has often clouded the distinction between myth and facts. This publication attempts to concerning the acid pollution situation. This publication attempts to identify available facts. It is the first global review of the problem of acid pollution and the first to…

McCormick, John

374

Acid rain abatement  

SciTech Connect

This patent describes a method of obtaining acid rain abatement from a flue gas containing nitrogen oxides (NOX) and sulfur oxides (SOX). It comprises the steps of treating the flue gas with a reducing agent to remove the remaining oxygen and produce an effluent, the reducing agent being selected from group consisting of natural gas, methane, a mixture of CO and hydrogen derived from steam, hydrocarbon, and hydrogen, passing effluent over a catalyst to simultaneously reduce the NOX to water and elemental nitrogen and the SOX to H{sub 2}S or elemental sulfur, the catalyst being selected from the group consisting of heteropoly acids and their salts, the reduction of the NOX and SOX taking place in a temperature range of 200{degrees} - 900{degrees} C., and removing the sulfur or sulfur compounds from the reduced flue gas to thereby remove essentially all of the NOX and SOX.

Stiles, A.B.

1991-06-11

375

Weak Acid Equilibrium  

NSDL National Science Digital Library

Students are asked to calculate the pH of a weak acid aqueous solution. The problems involve a series of generic acids with assigned equilibrium constants (Ka) and total concentrations (Ct). Initially, students are required to hand calculate all problems by algebraic manipulation of the mathematical relationships of the system. The solution is a cubic equation. Through a series of assumptions, the solution is simplified. The assumptions are based on the chemistry of the system given the Ka and Ct for the problem. The problems are then graphically solved. Ultimately, the students develop an Excel worksheet to solve the problems and a Bjerrum plot to display the speciation as a function of pH.

Stapleton, Michael

376

(Radioiodinated free fatty acids)  

SciTech Connect

The traveler participated in the Second International Workshop on Radioiodinated Free Fatty Acids in Amsterdam, The Netherlands where he presented an invited paper describing the pioneering work at the Oak Ridge National Laboratory (ORNL) involving the design, development and testing of new radioiodinated methyl-branched fatty acids for evaluation of heart disease. He also chaired a technical session on the testing of new agents in various in vitro and in vivo systems. He also visited the Institute for Clinical and Experimental Nuclear Medicine in Bonn, West Germany, to review, discuss, plan and coordinate collaborative investigations with that institution. In addition, he visited the Cyclotron Research Center in Liege, Belgium, to discuss continuing collaborative studies with the Osmium-191/Iridium-191m radionuclide generator system, and to complete manuscripts and plan future studies.

Knapp, Jr., F. F.

1987-12-11

377

Molecular Structure of Glutaric acid  

NSDL National Science Digital Library

Glutaric acid is a colorless liquid and white crystals as a solid occurring in plants and animal tissues. It is used in organic synthesis and as an intermediate for the manufacture of polymers such as polyamides and polyesters, ester plasticizers and corrosion inhibitors. It is also useful in the application of decreasing polymer elasticity and in a variety of industrial applications. In addition glutaric acid plays an important role as an intermediary in the Krebs cycle and is used in medication against a large number of viruses and in animal diabetes. Glutaric acid can be prepared from cyclopentanone by oxidative ring fission with nitric acid and in the presence of a catalyst. Glutaric acid has the lowest melting point among dicarboxylic acids (98 C); it is very soluble in water and the solution in water is a medium strong acid. Short-term exposure to glutaric acid may cause irritation to the eyes, skin and the respiratory tract.

2004-11-10

378

Mycolic Acids of Mycobacterium porcinum  

Microsoft Academic Search

The type strain of Mycobacterium porcinum had a characteristic pattern of a-, a'-, and epoxymycolic acids. This pattern of mycolic acids has been found previously only in representatives of M. farcinogenes, M. fortuitum, \\

M. LUQUIN; L. MARGARIT; M. J. CONDOM; V. AUSINA

1987-01-01

379

Omega-3 fatty acids (image)  

MedlinePLUS

Omega-3 fatty acids are a form of polyunsaturated fat that the body derives from food. Omega-3s (and omega-6s) are known as essential fatty acids (EFAs) because they are important for good health. ...

380

Crosslinked acid gels offer advantages  

SciTech Connect

Acid polymer gels having a pH less than one have been crosslinked for retarding the chemical and physical activity of hydrochloric acid on calcareous formations. Hydrochloric acid concentrations from /one quarter/% to 28% have been successfully crosslinked. This unique stimulation fluid offers high viscosity with adequate shear stability, perfect support for propants, and clay stabilization. Additionally, the fluid provided effective fluid loss control and retardation of acid reaction enabling live acid to penetrate deeper into the formation for better conductivity; furthermore, there is practically a residue free break for rapid cleanup of the well after the job. Results of lab and field tests show this new acid crosslinked system to be an effective stimulation fluid for acidizing and acid fracturing in calcareous and sandstone formations having low permeability. 5 refs.

Pabley, A.S.; Holcomb, D.L.

1981-09-28

381

Boric Acid Reclamation System (BARS).  

National Technical Information Service (NTIS)

KLM Technologies' personnel have identified a Boric Acid Reclamation System (BARS) utilizing reverse osmosis and ultrafiltration to produce a recyclable grade of otherwise waste boric acid at PWRs, thus reducing a major source of low-level radwaste. The d...

B. G. Kniazewycz J. Markind

1986-01-01

382

Ideas about Acids and Alkalis.  

ERIC Educational Resources Information Center

|Investigates students' ideas, conceptions, and misconceptions about acids and alkalis before and after a teaching sequence in a small-scale research project. Concludes that student understanding of acids and alkalis is lacking. (DDR)|

Toplis, Rob

1998-01-01

383

Biopolymers: Protein and Nucleic Acids.  

National Technical Information Service (NTIS)

The work focuses on learning the principles that govern interactions between proteins and nucleic acids. With these principles as guides we are synthesizing peptides (of about 50 amino acids) that bind to specific regions of DNA. Various reactive function...

J. H. Richards J. N. Abelson L. E. Hood M. I. Simon J. L. Campbell

1987-01-01

384

Acid rain options modeled  

NASA Astrophysics Data System (ADS)

Results from new computer models that could allow policymakers to compare different strategies for controlling acid rain will be presented at the AGU Spring Meeting in Baltimore, Md., May 18-21, 1987. The optimization models, developed by scientists from the Johns Hopkins University (Baltimore, Md.), are set up so that competing goals—for instance, reducing the deposition of sulfur without wiping out the high-sulfur coal industry— can be taken into account.

Katzoff, Judith A.

385

Acid rain in Asia  

Microsoft Academic Search

Acid rain has been an issue of great concern in North America and Europe during the past several decades. However, due to\\u000a the passage of a number of recent regulations, most notably the Clean Air Act in the United States in 1990, there is an emerging\\u000a perception that the problem in these Western nations is nearing solution. The situation in

Neeloo Bhatti; David G. Streets; Wesley K. Foell

1992-01-01

386

Lna (Locked Nucleic Acid)  

Microsoft Academic Search

LNA (Locked Nucleic Acid) forms duplexes with complementary DNA, RNA or LNA with unprecedented thermal affinities. CD spectra show that duplexes involving fully modified LNA (especially LNA:RNA) structurally resemble an A-form RNA:RNA duplex. NMR examination of an LNA:DNA duplex confirm the 3?-endo conformation of an LNA monomer. Recognition of double-stranded DNA is demonstrated suggesting strand invasion by LNA. Lipofectin-mediated efficient

Jesper Wengel; Alexei Koshkin; Sanjay K. Singh; Poul Nielsen; Michael Meldgaard; Vivek K. Rajwanshi; Ravindra Kumar; Jan Skouv; Christina B. Nielsen; Jens Peter Jacobsen; Nana Jacobsen; Carl E. Olsen

1999-01-01

387

Acid Rain Effects  

NSDL National Science Digital Library

Learners conduct a simple experiment to model and explore the harmful effects of acid rain (vinegar) on living (green leaf and eggshell) and non-living (paper clip) objects. Learners observe the effects over a period of days. This activity has links to other activities which can be combined to make a larger lesson. Resource contains vocabulary definitions and suggestions for assessment, extensions, and scaling for different levels of learners.

Kolenbrander, Amy; Yowell, Janet; Mach, Natalie; Zarske, Malinda S.; Carlson, Denise

2004-01-01

388

Optimize acid gas removal  

SciTech Connect

Innovative design of physical solvent plants for acid gas removal can materially reduce both installation and operating costs. A review of the design considerations for one physical solvent process (Selexol) points to numerous arrangements for potential improvement. These are evaluated for a specific case in four combinations that identify an optimum for the case in question but, more importantly, illustrate the mechanism for use for such optimization elsewhere.

Nicholas, D.M.; Wilkins, J.T.

1983-09-01

389

Grading acid rain research  

NASA Astrophysics Data System (ADS)

The growing concern with the environmental effects of acid rain has spawned a number of study groups in recent years, and now the Office of Science and Technology Policy (OSTP) has released what is essentially a study of a study. In January 1982, White House Science Advisor George Keyworth asked William Nierenberg, Director of the Scripps Institution of Oceanography, and a panel of nine scientists to conduct a peer review of three separate reports on acid deposition in eastern North America that had been turned in by U.S.-Canadian scientific working groups.Those studies had been requisitioned by a 1980 Memorandum of Intent between the United States and Canada regarding transboundary air pollution. Overall, the Nierenberg peer review panel was “impressed with the efforts of the United States-Canadian Working Groups,” (labeled Groups 1, 2, and 3B), but it also found problems. While applauding the work groups' exhaustive search through the acid rain literature, the Nierenberg panel cited what they call an “overdependence on ‘soft’ literature,” or writings such as in-house reports and personal communications, which are outside the publicly available (and carefully scrutinized) body of scientific literature.

390

Acid rain in Asia  

SciTech Connect

In Asia, fossil fuels are used in large quantities, such that local air pollution is becoming a serious problem and high deposition levels are being measured. Emission regulations in most countries (with the exception of Japan) are not very stringent. Energy plans in many countries call for very large increases in coal combustion in the future. Finally, there is not presently a strong constituency for action to mitigate the potential effects of acid deposition. These factors imply potentially serious problems in the future for long-range transport and deposition of sulfur and nitrogen species and consequent damage to ecosystems and materials. The political ramifications of transboundary environmental pollution in this region are also potentially serious. A predictive tool could be built to help decision makers project future trends in emissions, estimate the regional consequences for acid deposition levels, evaluate the vulnerability of natural and man-made systems, and determine the costs and effectiveness of alternative mitigative actions that might be taken. Such a policy analysis exercise can start to raise environmental awareness in the region and begin a dialogue that could help ameliorate an environmental problem in its early stages. The purpose of this paper is to provide background information on the acid deposition situation in Asia, with the intention of laying the foundation for the design of a possible research program for this region. 41 refs., 10 figs., 9 tabs.

Bhatti, N.; Streets, D.G. (Argonne National Lab., IL (USA)); Foell, W.K. (Resource Management Associates, Madison, WI (USA) Wisconsin Univ., Madison, WI (USA))

1989-01-01

391

Acid rain in Asia  

SciTech Connect

Acid rain has been an issue of widespread concern in North America and Europe for more than fifteen years. However, there is an emerging feeling that the problem in Europe and North America is nearing solution, largely as a result of existing and newly enacted legislation, decreased energy use due to conservation and efficiency improvements, and/or trends in energy policy away from fossil fuels. The situation in Asia appears much bleaker. Fossil fuels are already used in large quantities, such that local air pollution is becoming a serious problem and high deposition levels are being measured. Emission regulations in most countries (with the notable exception of Japan) are not very stringent. Energy plans in many countries (particularly PRC, India, Thailand, and South Korea) call for very large increases in coal combustion in the future. Finally, there is not presently a strong scientific or public constituency for action to mitigate the potential effects of acid deposition. These factors imply potentially serious problems in the future for long-range transport and deposition of sulfur and nitrogen species and consequent damage to ecosystems and materials. The political ramifications of transboundary environmental pollution in this region are also potentially serious. The purpose of this paper is to provide background information on the acid deposition situation in Asia, with the intention of laying the foundation for the development of a possible research program for this region. 36 refs., 8 figs., 8 tabs.

Bhatti, N.; Streets, D.G. (Argonne National Lab., IL (USA)); Foell, W.K. (Resource Management Associates, Madison, WI (USA))

1991-01-01

392

An amino acid transporter involved in gastric acid secretion.  

PubMed

Gastric acid secretion is regulated by a variety of stimuli, in particular histamine and acetyl choline. In addition, dietary factors such as the acute intake of a protein-rich diet and the subsequent increase in serum amino acids can stimulate gastric acid secretion only through partially characterized pathways. Recently, we described in mouse stomach parietal cells the expression of the system L heteromeric amino acid transporter comprised of the LAT2-4F2hc dimer. Here we address the potential role of the system L amino acid transporter in gastric acid secretion by parietal cells in freshly isolated rat gastric glands. RT-PCR, western blotting and immunohistochemistry confirmed the expression of 4F2-LAT2 amino acid transporters in rat parietal cells. In addition, mRNA was detected for the B(0)AT1, ASCT2, and ATB(0+) amino acid transporters. Intracellular pH measurements in parietal cells showed histamine-induced and omeprazole-sensitive H+-extrusion which was enhanced by about 50% in the presence of glutamine or cysteine (1 mM), two substrates of system L amino acid transporters. BCH, a non-metabolizable substrate and a competitive inhibitor of system L amino acid transport, abolished the stimulation of acid secretion by glutamine or cysteine suggesting that this stimulation required the uptake of amino acids by system L. In the absence of histamine glutamine also stimulated H+-extrusion, whereas glutamate did not. Also, phenylalanine was effective in stimulating H+/K+-ATPase activity. Glutamine did not increase intracellular Ca2+ levels indicating that it did not act via the recently described amino acid modulated Ca2+-sensing receptor. These data suggest a novel role for heterodimeric amino acid transporters and may elucidate a pathway by which protein-rich diets stimulate gastric acid secretion. PMID:16308696

Kirchhoff, Philipp; Dave, Mital H; Remy, Christine; Kosiek, Ortrud; Busque, Stephanie M; Dufner, Matthias; Geibel, John P; Verrey, Francois; Wagner, Carsten A

2005-11-25

393

Molecular Structure of Acetic acid  

NSDL National Science Digital Library

Acetic Acid commonly associated with vinegar; it is the most commercially important organic acid and is used to manufacture a wide range of chemical products, such as plastics and insecticides. Acetic acid is produced naturally by Aceto bacteria but, except for making vinegar, is usually made through synthetic processes. Ethanoic acid is used as herbicide, as a micro-biocide, as a fungicide and for pH adjustment.

2003-06-02

394

Fatty acid signaling in Arabidopsis  

Microsoft Academic Search

.   Many organisms use fatty acid derivatives as biological regulators. In plants, for example, fatty acid-derived signals have\\u000a established roles in the regulation of developmental and defense gene expression. Growing numbers of these compounds, mostly\\u000a derived from fatty acid hydroperoxides, are being characterized. The model plant Arabidopsis thaliana is serving a vital role in the discovery of fatty acid-derived signal

Edward E. Farmer; Hans Weber; Sabine Vollenweider

1998-01-01

395

Molecular Structure of Octanoic acid  

NSDL National Science Digital Library

Caprylic acid is a colorless oil manufactured from 1-heptene or 1-octanol. Octanoic acid has an unpleasant rancid taste. When converted from the carboxlic acid to an ester, it has a pleasant taste. In addition, esters of caprylic acid are used in the preparation of dyes, perfumes, and food preservatives. This compound has also been found to have antifungal activity and is used to treat yeast infections.

2002-10-11

396

Acid rain: Reign of controversy  

SciTech Connect

Acid Rain is a primer on the science and politics of acid rain. Several introductory chapters describe in simple terms the relevant principles of water chemistry, soil chemistry, and plant physiology and discuss the demonstrated or postulated effects of acid rain on fresh waters and forests as well as on statuary and other exposed objects. There follow discussions on the economic and social implications of acid rain (for example, possible health effects) and on the sources, transport, and distribution of air pollutants.

Kahan, A.M.

1986-01-01

397

A radioimmunoassay for abscisic acid  

Microsoft Academic Search

We have developed a radioimmunoassay (RIA) for abscisic acid (ABA) in the 0.1 ng to 2.5 ng range. Antibodies were obtained from rabbits immunized with ABA bound via its carboxyl group to bovine serum albumin. Cross-reactivity studies indicate that ABA esters are completely cross-reactive with ABA, while trans, trans abscisic acid (t-ABA) phaseic acid (PA) and dihydrophaseic acid (DPA) have

Daniel Walton; William Dashek; Eva Galson

1979-01-01

398

Molecular Structure of Trimesic acid  

NSDL National Science Digital Library

Trimesic Acid is made up of a benzene ring with three carboxylic groups at the 1, 3, and 5 positions, and it can be synthesized from the oxidation of 1,3,5-trimethyl benzene. The acid is an important building block in crystal engineering which is used to form honeycomb structures, but it has the ability to form diverse supramolecular structures. Also, trimesic acid salt and the free trimesic acid are useful as a plasticizer.

2003-05-08

399

Radioenzymatic assay for quinolinic acid  

Microsoft Academic Search

A new and rapid method for the determination of the excitotoxic tryptophan metabolite quinolinic acid is based on its enzymatic conversion to nicotinic acid mononucleotide and, in a second step utilizing (³H)ATP, further to (³H) deamido-NAD. Specificity of the assay is assured by using a highly purified preparation of the specific quinolinic acid-catabolizing enzyme, quinolinic acid phosphoribosyltransferase, in the initial

A. C. Foster; E. Okuno; D. S. Brougher; R. Schwarcz

1986-01-01

400

Levulinic acid in organic synthesis  

NASA Astrophysics Data System (ADS)

Data concerning the methods of synthesis, chemical transformations and application of levulinic acid are analysed and generalised. The wide synthetic potential of levulinic acid, particularly as a key compound in the synthesis of various heterocyclic systems, saturated and unsaturated ketones and diketones, difficultly accessible acids and other compounds is demonstrated. The accessibility of levulinic acid from hexose-containing wood-processing and agricultural wastes is noted. The bibliography includes 260 references.

Timokhin, Boris V.; Baransky, V. A.; Eliseeva, G. D.

1999-01-01

401

Determination of Mine Waste Acidity.  

National Technical Information Service (NTIS)

Pollution from acid mine drainage is a chronic problem. The current vigorous interest has led to a re-examination of the methods of measuring total acidity, which are clearly based on the limited laboratory capabilities of prior years. Defined acid-metal ...

B. V. Salotto E. F. Barth M. B. Ettinger W. E. Tolliver

1967-01-01

402

Carboxylic acid sorption regeneration process  

DOEpatents

Carboxylic acids are sorbed from aqueous feedstocks into an organic liquid phase or onto a solid adsorbent. The acids are freed from the sorbent phase by treating it with aqueous alkylamine thus forming an alkylammonium carboxylate which is dewatered and decomposed to the desired carboxylic acid and the alkylamine.

King, C. Judson (Kensington, CA); Poole, Loree J. (Baton Rouge, LA)

1995-01-01

403

Acidic compounds in biodegraded petroleum  

Microsoft Academic Search

Twelve oil samples have been characterised by titration, FT-IR and chromatographic analysis to determine the differences between the organic acid composition of biodegraded and non-biodegraded oils. The biodegraded oils have higher total acid and total base contents, both by titration and extraction. The molecular weight ranges of the extracted acids are lowest in the biodegraded oils, and the equivalent weight

Tanja Barth; Sylvi Høiland; Per Fotland; Kjell Magne Askvik; Bent Skaare Pedersen; Anna Elisabet Borgund

2004-01-01

404

New politics of acid rain  

SciTech Connect

The acid rain problem is not nationwide across the USA but the politicians want to spread the cost of emission reductions. An overview of acid rain and its environmental impacts is given, and a cost-benefit analysis of acid rain control is outlined. USA policies are discussed. 6 references.

Trisko, E.M.

1983-07-01

405

Synthesis of Acetylsalicylic Acid (Aspirin)  

Microsoft Academic Search

The purpose of this experiment was to synthesize acetylsalicylic acid via an esterification reaction between salicylic acid and acetic anhydride. The product was recrystallized using 95% ethanol. This percent yield of this synthesized product was 68.4%. Using ethanol again as a recrystallizing solvent, acetylsalicylic acid was also extracted from commercial aspirin tablets. This commercial product did not have a percent

Jamie Yeadon; Leah Monroe

406

Serum Uric Acid in Smokers  

PubMed Central

Objectives To demonstrate the possible effect of smoking on serum uric acid. Methods Subjects enrolled in study were divided into two groups; nonsmokers and smokers, each with 60 male volunteers of the same social class and dietary habit without history of alcohol consumption, diabetes mellitus, hyperuricemia and gout, renal, joint, lung or heart diseases. Fasting blood and random urine samples were obtained from both groups for measurement of uric acid and creatinine. Calculation of both urine uric acid/urine creatinine ratio and fraction excretion of uric acid were done. The results were statistically evaluated by standard statistical methods. Results No significant differences in the age, serum creatinine, spot urine uric acid/urine creatinine ratio and fraction excretion of uric acid between the two groups, serum uric acid was significantly lower in smokers. In smokers there was significant negative correlation of smoking status (average number of cigarette smoked/day, duration of smoking and cumulative amount of smoking) with serum uric acid. Conclusion After exclusion of other factors affecting uric acid level, the significant low serum uric acid level in smokers was attributed to reduce endogenous production as a result of chronic exposure to cigarette smoke that is a significant source of oxidative stress. As this reduction is proportionate with smoking status and predisposes to cardiovascular disease, it is, therefore, recommended for smokers to stop or reduce smoking and introduce serum uric acid estimation as routine test since its cheap and simple to reflect their antioxidant level. Keywords Smokers; Uric acid; CVD.

Hanna, Bassam E.; Hamed, Jamal M.; Touhala, Luma M.

2008-01-01

407

Stimulation with inhibited acidizing fluids  

Microsoft Academic Search

Production and injection wells are stimulated with an inhibited acidizing microemulsion containing hydrocarbon (external phase), surfactant, and acid. The acid is inhibited from reacting with the reservoir rock until it has penetrated the rock face. About 5 to 500 gal of the microemulsion per vertical foot of formation are useful to stimulate the wells. Carbonate reservoirs are particulary suited for

C. T. Presley; R. E. Smith

1974-01-01

408

Bacterial Degradation of Nicotinic Acid  

Microsoft Academic Search

A BACTERIUM utilizing nicotinic acid was isolated from culture media made up of a solution of nicotinic acid and dilute sodium sulphide and inoculated with a small amount of Potomac mud. After allowing the bacteria to grow anaerobically, several successive transfers were made into a medium containing nicotinic acid, peptone, yeast extract, metals, phosphate and sodium sulphide. The mixed bacterial

Isaac Harary

1956-01-01

409

An Umbrella for Acid Rain.  

ERIC Educational Resources Information Center

|The Environmental Protection Agency has awarded several grants to study effects of and possible solutions to the problem of "acid rain"; pollution from atmospheric nitric and sulfuric acids. The research program is administered through North Carolina State University at Raleigh and will focus on biological effects of acid rain. (JMF)|

Randal, Judith

1979-01-01

410

Scientists Puzzle Over Acid Rain  

ERIC Educational Resources Information Center

|Reports on a growing concern over increased acidity in atmospheric percipitation. Explores possible causes of the increased acidity, identifies chemical components of precipitation in various parts of the world, and presents environmental changes that might be attributed to the acidity. (GS)|

Chemical and Engineering News, 1975

1975-01-01

411

Acid-hydrolysis of fish wastes for lactic acid fermentation.  

PubMed

In this study, two acid-hydrolysis processes, process A and process B, were proposed to produce low-cost nutrients for the production of lactic acid. Process A was a direct way to hydrolyze protein with diluted acid while process B was process A plus fish wastes pretreatment (an extraction by water). The two methods could both treat fish wastes to be suitable nutrient sources for promoting lactic acid production. As the pretreatment indicated some favorable effect on fish waste hydrolyzate (FWH), process B increased lactic acid productivity by 22%. Compared with 20 g/L yeast extract (YE), 6.8% FWH hydrolyzed by process B had more efficiency in lactic acid production, indicating that process B was suitable to produce high performance nutrients for lactic acid production and FWH hydrolyzed by process B would be an substitute for YE. PMID:16293413

Gao, Min-Tian; Hirata, Makoto; Toorisaka, Eiichi; Hano, Tadashi

2005-11-15

412

Caffeic acid derivatives from Eupatorium perfoliatum L.  

PubMed

From the ethyl acetate soluble fraction of a methanol/water extract of the herb Eupatorium perfoliatum L. (Asteraceae) six caffeic acid derivatives have been isolated and identified by 1D- and 2D-NMR spectroscopic data. Besides the common quinic acid derivatives 5-caffeoylquinic acid (chlorogenic acid), 3-caffeoylquinic acid (neochlorogenic acid) and 3,5-dicaffeoylquinic acid, three up to now unknown depsides of caffeic acid with glucaric acid have been isolated: 2,5-dicaffeoylglucaric acid, 3,4-dicaffeoylglucaric acid, and 2,4- or 3,5-dicaffeoylglucaric acid. PMID:19104484

Maas, Mareike; Petereit, Frank; Hensel, Andreas

2008-12-23

413

Composition for nucleic acid sequencing  

DOEpatents

The present invention is directed to a method of sequencing a target nucleic acid molecule having a plurality of bases. In its principle, the temporal order of base additions during the polymerization reaction is measured on a molecule of nucleic acid, i.e. the activity of a nucleic acid polymerizing enzyme on the template nucleic acid molecule to be sequenced is followed in real time. The sequence is deduced by identifying which base is being incorporated into the growing complementary strand of the target nucleic acid by the catalytic activity of the nucleic acid polymerizing enzyme at each step in the sequence of base additions. A polymerase on the target nucleic acid molecule complex is provided in a position suitable to move along the target nucleic acid molecule and extend the oligonucleotide primer at an active site. A plurality of labelled types of nucleotide analogs are provided proximate to the active site, with each distinguishable type of nucleotide analog being complementary to a different nucleotide in the target nucleic acid sequence. The growing nucleic acid strand is extended by using the polymerase to add a nucleotide analog to the nucleic acid strand at the active site, where the nucleotide analog being added is complementary to the nucleotide of the target nucleic acid at the active site. The nucleotide analog added to the oligonucleotide primer as a result of the polymerizing step is identified. The steps of providing labelled nucleotide analogs, polymerizing the growing nucleic acid strand, and identifying the added nucleotide analog are repeated so that the nucleic acid strand is further extended and the sequence of the target nucleic acid is determined.

Korlach, Jonas (Ithaca, NY); Webb, Watt W. (Ithaca, NY); Levene, Michael (Ithaca, NY); Turner, Stephen (Ithaca, NY); Craighead, Harold G. (Ithaca, NY); Foquet, Mathieu (Ithaca, NY)

2008-08-26

414

Degradation of Phthalic Acids and Benzoic Acid from Terephthalic Acid Wastewater by Advanced Oxidation Processes  

Microsoft Academic Search

Terephthalic acid (TPA) wastewater is traditionally being treated by biological method. This study investigates the degradation of three major toxic target organic species, namely terephthalic acid (TPA), isophthalic acid (IPA), benzoic acid (BA), present in the TPA wastewater, by several advanced oxidation processes. The performance of three main oxidation processes such as photofenton oxidation (UV-H2O2-Fe), photocatalytic ozonation (UV-O3-Fe) and photofenton

Ramesh Thiruvenkatachari; Tae Ouk Kwon; Il Shik Moon

2006-01-01

415

The politics of acid rain  

SciTech Connect

This work examines and compares the acid rain policies through the different political systems of Canada, Great Britain and the United States. Because the flow of acid rain can transcend national boundaries, acid rain has become a crucial international problem. According to the author, because of differences in governmental institutions and structure, the extent of governmental intervention in the industrial economy, the degree of reliance on coal for power generation, and the extent of acid rain damage, national responses to the acid rain problem have varied.

Wilcher, M.E. (Pennsylvania State Univ., New Kensington, PA (US))

1989-01-01

416

Tested Demonstrations: Color Oscillations in the Formic Acid-Nitric Acid-Sulfuric Acid System.  

ERIC Educational Resources Information Center

|Presented are procedures for demonstrating the production of color oscillations when nitric acid is added to a formic acid/concentrated sulfuric acid mixture. Because of safety considerations, "Super-8" home movie of the color changes was found to be satisfactory for demonstration purposes. (JN)|

Raw, C. J. G.; And Others

1983-01-01

417

Some Physical Properties of Binary Liquid Systems: (Ethanoic Acid or Propanoic Acid or Butanoic Acid + Ethanenitrile)  

Microsoft Academic Search

Density, viscosity and surface tension of three binary liquid systems: ethanoic acid + ethanenitrile, propanoic acid + ethanenitrile, butanoic acid + ethanenitrile have been determined at 25, 35 and 45°C, over the whole compositional range. The excess values of molar volume, viscosity, Gibbs free energy for the activation of flow and surface tension were evaluated. The excess values were fitted

R. Ahluwalia; R. K. Wanchoo; J. L. Vashisht

1995-01-01

418

Amino acids in Arctic aerosols  

NASA Astrophysics Data System (ADS)

Amino acids are significant components of atmospheric aerosols, affecting organic nitrogen input to marine ecosystems, atmospheric radiation balance, and the global water cycle. The wide range of amino acid reactivities suggest that amino acids may serve as markers of atmospheric transport and deposition of particles. Despite this potential, few measurements have been conducted in remote areas to assess amino acid concentrations and potential sources. Polar regions offer a unique opportunity to investigate atmospheric processes and to conduct source apportionment studies of such compounds. In order to better understand the importance of amino acid compounds in the global atmosphere, we determined free amino acids (FAAs) in seventeen size-segregated aerosol samples collected in a polar station in the Svalbard Islands from 19 April until 14 September 2010. We used an HPLC coupled with a tandem mass spectrometer (ESI-MS/MS) to analyze 20 amino acids and quantify compounds at fmol m-3 levels. Mean total FAA concentration was 1070 fmol m-3 where serine and glycine were the most abundant compounds in almost all samples and accounted for 45-60% of the total amino acid relative abundance. The other eighteen compounds had average concentrations between 0.3 and 98 fmol m-3. The higher amino acid concentrations were present in the ultrafine aerosol fraction (< 0.49 ?m) and accounted for the majority of the total amino acid content. Local marine sources dominate the boreal summer amino acid concentrations, with the exception of the regional input from Icelandic volcanic emissions.

Scalabrin, E.; Zangrando, R.; Barbaro, E.; Kehrwald, N. M.; Gabrieli, J.; Barbante, C.; Gambaro, A.

2012-11-01

419

Allelopathic interactions involving phenolic acids.  

PubMed

A major concern regarding allelopathic interactions involving phenolic acids in no-till systems pertains to the fact that concentrations of individual phenolic acids recoverable from field soils are well below levels required for inhibition of germination and seedling growth in laboratory bioassays. Field soils contain a variety of phenolic acids as well as other toxic and nontoxic organic compounds that are available to interact with seeds and roots; whereas in laboratory bioassays, with few exceptions, single phenolic acids have been tested. Studies of mixtures of phenolic acids and other toxic (e.g., methionine) and nontoxic (e.g., glucose) organic compounds in laboratory bioassays indicate that the action of a single phenolic acid is not representative of the actions of such mixtures. Specifically, as the number of phenolic acids added to soil increased, concentrations of the individual phenolic acids required to bring about a growth inhibition declined. The addition of other organic compounds (e.g., glucose, methionine) to the soil also reduced the concentration of a phenolic acid (e.g., p-coumaric acid) required for growth inhibition. These results support the hypothesis that in the field mixtures of phenolic acids and other organic compounds can cause inhibitory effects even though the concentrations of individual compounds are well below their inhibitory levels. PMID:19277143

Blum, U

1996-09-01

420

Do we need gastric acid?  

PubMed

Evidence from comparative anatomy and physiology studies indicates that gastric acid secretion developed during the evolution of vertebrates approximately 350 million years ago. The cellular mechanisms that produce gastric acid have been conserved over the millennia and therefore proton pump inhibitors have pharmacological effects in almost all relevant species. These observations suggest that gastric acid provides an important selective advantage; however, in modern-day humans the need for gastric acid can be questioned in light of the widespread use of safe and effective pharmacologic acid suppression. The Kandahar Working Group addressed questions concerning the need, production and effects of gastric acid, specifically: (1) motility in the upper gastrointestinal (GI) tract; (2) neuroendocrine factors; (3) digestive and mucosal processes; (4) microbiology, and (5) central processes and psychological involvement. We addressed each topic with the individual models available to answer our questions including animal versus human studies, pharmacologic, surgical as well as pathophysiologic states of acid suppression. PMID:18594142

Pohl, D; Fox, M; Fried, M; Göke, B; Prinz, C; Mönnikes, H; Rogler, G; Dauer, M; Keller, J; Lippl, F; Schiefke, I; Seidler, U; Allescher, H D

2008-07-02

421

Molecular Structure of Picric acid  

NSDL National Science Digital Library

Picric Acid was first discovered in 1771 by a British Chemist named Peter Woulfe by treatment of indigo with nitric acid. It is most commonly seen in its yellow, water-soluble, crystalline form. For this reason, picric acid first saw use as a dyeing agent in textiles. However, around 1849 it was discovered (for obvious reasons) that picric acid is a shock, heat, and friction-sensitive explosive. Its first use as an explosive material came in military weaponry: torpedoes in particular due to its shock-sensitive nature not requiring a detonator to explode on contact with a target. However, picric acid was found to be highly corrosive to metals, making the weapons very difficult to handle and the acid itself difficult to store. Today, picric acid is used more widely as an ingredient in the manufacture of inert dyes and stable explosives such as dynamite.

2002-09-23

422

Pathophysiology of uric acid nephrolithiasis.  

PubMed

Humans although a predominantly ureotylic organism, has preserved the ability to excrete nitrogen as uric acid and ammonia. An imbalance between these two secondary modes of nitrogen excretion has resulted in uric acid precipitation in human urine. Uric acid nephrolithiasis can arise from diverse etiologies all with distinct underlying defects converging to one or more of three defects of hyperuricosuria, acidic urine pH, and low urinary volume, originating from secondary, genetic or heretofore undefined (idiopathic) causes. A subset of idiopathic uric acid nephrolithiasis (gouty diathesis) may be the "tip of the icebergp" of a broader systemic illness characterized by insulin resistance. A novel renal manifestation of insulin resistance is a mild defect in ammonium excretion, which is not severe enough to disturb acid-base homeostasis, but is sufficient to set up the chemical milieu for uric acid nephrolithiasis. PMID:12474637

Moe, Orson W; Abate, Nicola; Sakhaee, Khashayar

2002-12-01

423

Molecular Structure of Sorbic acid  

NSDL National Science Digital Library

Sorbic acid is a colorless or white crystalline powder, with a weak characteristic odor and slightly acidic taste. It may be obtained from berries of the mountain ash or prepared synthetically by condensing crotonaldehyde and malonic acid in pyridine solution. Sorbic acid is a polyunsaturated fat used to inhibit molds and yeast, is a fungistatic agent for foods (especially cheeses, wine and baked goods). The main use of sorbic acid is as a preservative in foods, animal feeds, tobacco, cosmetics and pharmaceuticals, as well in packing materials for these substances and in other products that come in contact with human or animal skin in some way. Sorbic acid is also used as an intermediate for plasticizers and lubricants. Sorbic acid reacts with potassium to make potassium sorbate and with calcium to make calcium sorbate.

2004-11-11

424

Mycophenolic Acid in Silage  

PubMed Central

We examined 233 silage samples and found that molds were present in 206 samples with counts between 1 × 103 and 8.9 × 107 (mean, 4.7 × 106) CFU/g. Mycophenolic acid, a metabolite of Penicillium roqueforti, was detected by liquid chromatography-mass spectrometry in 74 (32%) of these samples at levels ranging from 20 to 35,000 (mean, 1,400) ?g/kg. This compound has well-known immunosuppressive properties, so feeding with contaminated silage may promote the development of infectious diseases in livestock.

Schneweis, Isabell; Meyer, Karsten; Hormansdorfer, Stefan; Bauer, Johann

2000-01-01

425

Cytenamide acetic acid solvate  

PubMed Central

In the crystal structure of the title compound (systematic name: 5H-dibenzo[a,d]cyclo­hepta­triene-5-carboxamide ethanoic acid solvate), C16H13NO·C2H4O2, the cytenamide and solvent mol­ecules form a hydrogen-bonded R 2 2(8) dimer motif, which is further connected to form a centrosymmetric double ring motif arrangement. The cycloheptene ring adopts a boat conformation and the dihedral angle between the least-squares planes through the two aromatic rings is 54.7?(2)°.

Johnston, Andrea; Florence, Alastair J.; Fabianni, Francesca J. A.; Shankland, Kenneth; Bedford, Colin T.

2008-01-01

426

Cytenamide acetic acid solvate.  

PubMed

IN THE CRYSTAL STRUCTURE OF THE TITLE COMPOUND (SYSTEMATIC NAME: 5H-dibenzo[a,d]cyclo-hepta-triene-5-carboxamide ethanoic acid solvate), C(16)H(13)NO·C(2)H(4)O(2), the cytenamide and solvent mol-ecules form a hydrogen-bonded R(2) (2)(8) dimer motif, which is further connected to form a centrosymmetric double ring motif arrangement. The cycloheptene ring adopts a boat conformation and the dihedral angle between the least-squares planes through the two aromatic rings is 54.7?(2)°. PMID:21202682

Johnston, Andrea; Florence, Alastair J; Fabianni, Francesca J A; Shankland, Kenneth; Bedford, Colin T

2008-05-30

427

Synthesis of amino acids  

DOEpatents

A method is described for synthesizing amino acids preceding through novel intermediates of the formulas: R/sub 1/R/sub 2/C(OSOC1)CN, R/sub 1/R/sub 2/C(C1)CN and (R/sub 1/R/sub 2/C(CN)O)/sub 2/SO wherein R/sub 1/ and R/sub 2/ are each selected from hydrogen and monovalent hydrocarbon radicals of 1 to 10 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the synthesis methods of the prior art.

Davis, J.W. Jr.

1979-09-21

428

Beyond acid rain  

SciTech Connect

This paper discussed the effects of the interactions of soluble oxidants and organic toxins with sulfur dioxide and nitrogen dioxide. It suggested that these chemical reactions in the atmosphere produced a more potent acid rain which was harmful not only because it had a low pH but because it contained oxidants and organic toxins which were harmful to surface vegetation and the organisms found in surface waters. It was stressed that air pollution is a global problem and that is is necessary to develop a better fundamental understanding of how air pollution is causing damage to the streams and forests of the world. 50 references.

Gaffney, J.S.; Streit, G.E.; Spall, W.D.; Hall, J.H.

1987-06-01

429

Conformational studies of hydantoin-5-acetic acid and orotic acid.  

PubMed

Hydantoin-5-acetic acid [2-(2,5-dioxoimidazolidin-4-yl)acetic acid] and orotic acid (2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylic acid) each contain one rigid acceptor-donor-acceptor hydrogen-bonding site and a flexible side chain, which can adopt different conformations. Since both compounds may be used as coformers for supramolecular complexes, they have been crystallized in order to examine their conformational preferences, giving solvent-free hydantoin-5-acetic acid, C(5)H(6)N(2)O(4), (I), and three crystals containing orotic acid, namely, orotic acid dimethyl sulfoxide monosolvate, C(5)H(4)N(2)O(4)·C(2)H(6)OS, (IIa), dimethylammonium orotate-orotic acid (1/1), C(2)H(8)N(+)·C(5)H(3)N(2)O(4)(-)·C(5)H(4)N(2)O(4), (IIb), and dimethylammonium orotate-orotic acid (3/1), 3C(2)H(8)N(+)·3C(5)H(3)N(2)O(4)(-)·C(5)H(4)N(2)O(4), (IIc). The crystal structure of (I) shows a three-dimensional network, with the acid function located perpendicular to the ring. Interestingly, the hydroxy O atom acts as an acceptor, even though the carbonyl O atom is not involved in any hydrogen bonds. However, in (IIa), (IIb) and (IIc), the acid functions are only slightly twisted out of the ring planes. All H atoms of the acidic functions are directed away from the rings and, with respect to the carbonyl O atoms, they show an antiperiplanar conformation in (I) and synperiplanar conformations in (IIa), (IIb) and (IIc). Furthermore, in (IIa), (IIb) and (IIc), different conformations of the acid O=C-C-N torsion angle are observed, leading to different hydrogen-bonding arrangements depending on their conformation and composition. PMID:22307261

Gerhardt, Valeska; Tutughamiarso, Maya; Bolte, Michael

2012-01-18

430

Circulating folic acid in plasma: relation to folic acid fortification  

PubMed Central

Background The implementation of folic acid fortification in the United States has resulted in unprecedented amounts of this synthetic form of folate in the American diet. Folic acid in circulation may be a useful measure of physiologic exposure to synthetic folic acid, and there is a potential for elevated concentrations after fortification and the possibility of adverse effects. Objective We assessed the effect of folic acid fortification on circulating concentrations of folic acid and 5-methyltetrahydrofolate in the Framingham Offspring Cohort. Design This is a cross-sectional study that used plasma samples from fasting subjects before and after fortification. Samples were measured for folate distribution with the use of an affinity-HPLC method with electrochemical detection. Results Among nonsupplement users, the median concentration of folic acid in plasma increased from 0.25 to 0.50 nmol/L (P < 0.001) after fortification, and among supplement users the median increased from 0.54 to 0.68 nmol/L (P = 0.001). Among nonsupplement users, the prevalence of high circulating folic acid (?85th percentile) increased from 9.4% to 19.1% (P = 0.002) after fortification. Among supplement users, the prevalence of high circulating folic acid increased from 15.9% to 24.3% (P = 0.02). Folic acid intake and total plasma folate were positively and significantly related to high circulating folic acid after adjustment for potential confounding factors (P for trend < 0.001). Conclusions Folic acid fortification has resulted in increased exposure to circulating folic acid. The biochemical and physiologic consequences of this are unknown, but these findings highlight the need to understand the effects of chronic exposure to circulating folic acid.

Kalmbach, Renee D; Choumenkovitch, Silvina F; Troen, Aron M; D'Agostino, Ralph; Jacques, Paul F; Selhub, Jacob

2013-01-01

431

Cloning and Expression of the Gene for the Na+-Coupled Serine Transporter from Escherichia coli and Characteristics of the Transporter  

PubMed Central

We cloned a gene (sstT) for the Na+/serine symporter from the chromosome of Escherichia coli by using a low-copy-number vector and sequenced it. According to the deduced amino acid sequence, the transporter (SstT) consists of 414 amino acid residues. Hydropathy analysis suggested that the SstT protein possesses 9, instead of 12, hydrophobic domains.

Ogawa, Wakano; Kim, Young-Mog; Mizushima, Tohru; Tsuchiya, Tomofusa

1998-01-01

432

Lipid metabolism in the perfused chicken liver. The uptake and metabolism of oleic acid, elaidic acid, cis-vaccenic acid, trans-vaccenic acid and stearic acid  

PubMed Central

Comparative studies were made of the uptake and metabolism of cis- and trans-octadecenoic acids by the perfused chicken liver. No differences were observed in the rates of uptake of the isomers. There was considerable incorporation of radioactivity into triglycerides and phospholipids, and some release of labelled lipid into the perfusate was observed. The cis-fatty acids were more readily incorporated into triglycerides than phospholipids, the reverse being true of the trans-fatty acids. Examination of the intramolecular distribution of fatty acids in triglycerides showed that the trans-fatty acid and stearate mainly occupied the 1- and 3-positions, and cis-fatty acids the 2-position. In the phospholipids phosphatidylcholine and phosphatidylethanolamine the trans-fatty acids again behaved like stearic acid and favoured the 1-position. No evidence was obtained of atypical patterns of uptake or metabolism of the trans-fatty acids.

Bickerstaffe, R.; Annison, E. F.

1970-01-01

433

Preparation of the 3-monosulphates of cholic acid, chenodeoxycholic acid and deoxycholic acid.  

PubMed Central

1. The 3-sulphates of cholic, chenodeoxycholic and deoxycholic acids were prepared as crystalline disodium salts. 2. The method described shows that it is possible to prepare specific sulphate esters of polyhydroxy bile acids and to remove protecting acyl groups without removing the sulphate. 3. A study of bile acid sulphate solvolysis showed that none of the usual methods give the original bile acid in major yield in a single step. 4. An understanding of the preparation, properties and methods of solvolysis of bile acid sulphates is basic for investigations of cholestasis and liver disease.

Haslewood, E S; Haslewood, G A

1976-01-01

434

Action of picolinic acid and structurally related pyridine carboxylic acids on quinolinic acid-induced cortical cholinergic damage  

Microsoft Academic Search

Picolinic acid, a pyridine monocarboxylic acid derived from tryptophan metabolism by the kynurenine pathway, was shown to block cortical cholinergic neurotoxicity induced by quinolinic acid (QUIN), a pyridine dicarboxylic acid yielded by the same pathway. This study examined the specificity of the anti-toxic effect of picolinic acid by comparing its effect with several structurally related mono- and dicarboxylic acids, and

J. Cockhill; K. Jhamandas; R. J. Boegman; R. J. Beninger

1992-01-01

435

21 CFR 184.1069 - Malic acid.  

Code of Federal Regulations, 2010 CFR

...referred to as L-malic acid, occurs naturally in...foods. Racemic DL-malic acid does not occur naturally...commercially by hydration of fumaric acid or maleic acid...percent for nonalcoholic beverages as defined in §...

2009-04-01

436

21 CFR 184.1069 - Malic acid.  

Code of Federal Regulations, 2010 CFR

...referred to as L-malic acid, occurs naturally in...foods. Racemic DL-malic acid does not occur naturally...commercially by hydration of fumaric acid or maleic acid...percent for nonalcoholic beverages as defined in §...

2010-01-01

437

An orsellinic acid glucoside from syzygium aromatica  

Microsoft Academic Search

The buds of Syzygium aromatica yielded two triterpenoid acids, oleanolic acid and crategolic acid, and a new phenolic glucoside, orsellinic-2-O-?-d-glucopyranoside, from its methanolic extract. The structure was elucidated by spectroscopic methods and acid hydrolysis.

Reena Charles; Shri Niwas Garg; Sushil Kumar

1998-01-01

438

Solid-phase extraction of acidic herbicides.  

PubMed

A discussion of solid-phase extraction method development for acidic herbicides is presented that reviews sample matrix modification, extraction sorbent selection, derivatization procedures for gas chromatographic analysis, and clean-up procedures for high-performance liquid chromatographic analysis. Acidic herbicides are families of compounds that include derivatives of phenol (dinoseb, dinoterb and pentachlorophenol), benzoic acid (acifluorfen, chloramben, dicamba, 3,5-dichlorobenzoic acid and dacthal--a dibenzoic acid derivative), acetic acid [2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)], propanoic acid [dichlorprop, fluazifop, haloxyfop, 2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP) and silvex], butanoic acid [4-(2,4-dichlorophenoxy)butanoic acid (2,4-DB) and 4-(4-chloro-2-methylphenoxy)butanoic acid (MCPB)], and other miscellaneous acids such as pyridinecarboxylic acid (picloram) and thiadiazine dioxide (bentazon). PMID:10941675

Wells, M J; Yu, L Z

2000-07-14

439

21 CFR 184.1091 - Succinic acid.  

Code of Federal Regulations, 2010 CFR

...acid, is the chemical 1,4-butanedioic acid. It is commercially prepared by hydrogenation of maleic or fumaric acid. It can also be produced by aqueous alkali or acid hydrolysis of succinonitrile....

2010-01-01

440

Cryoprotection from lipoteichoic acid  

NASA Astrophysics Data System (ADS)

Numerous chemical additives lower the freezing point of water, but life at sub-zero temperatures is sustained by a limited number of biological cryoprotectants. Antifreeze proteins in fish, plants, and insects provide protection to a few degrees below freezing. Microbes have been found to survive at even lower temperatures, and with a few exceptions, antifreeze proteins are missing. Survival has been attributed to external factors, such as the high salt concentration of brine veins and adhesion to particulates or ice crystal defects. We have discovered an endogenous cryoprotectant in the cell wall of bacteria, lipoteichoic acid biopolymers. Adding 1% LTA to bacteria cultures immediately prior to freezing provides 50% survival rate, similar to the results obtained with 1% glycerol. In the absence of an additive, bacterial survival is negligible as measured with the resazurin cell viability assay. The mode of action for LTA cryoprotection is unknown. With a molecular weight of 3-5 kDa, it is unlikely to enter the cell cytoplasm. Our observations suggest that teichoic acids could provide a shell of liquid water around biofilms and planktonic bacteria, removing the need for brine veins to prevent bacterial freezing.

Rice, Charles V.; Middaugh, Amy; Wickham, Jason R.; Friedline, Anthony; Thomas, Kieth J.; Johnson, Karen; Zachariah, Malcolm; Garimella, Ravindranth

2012-10-01

441

Nucleic acid detection methods  

DOEpatents

The invention relates to methods for rapidly determining the sequence and/or length a target sequence. The target sequence may be a series of known or unknown repeat sequences which are hybridized to an array of probes. The hybridized array is digested with a single-strand nuclease and free 3{prime}-hydroxyl groups extended with a nucleic acid polymerase. Nuclease cleaved heteroduplexes can be easily distinguish from nuclease uncleaved heteroduplexes by differential labeling. Probes and target can be differentially labeled with detectable labels. Matched target can be detected by cleaving resulting loops from the hybridized target and creating free 3-hydroxyl groups. These groups are recognized and extended by polymerases added into the reaction system which also adds or releases one label into solution. Analysis of the resulting products using either solid phase or solution. These methods can be used to detect characteristic nucleic acid sequences, to determine target sequence and to screen for genetic defects and disorders. Assays can be conducted on solid surfaces allowing for multiple reactions to be conducted in parallel and, if desired, automated. 18 figs.

Smith, C.L.; Yaar, R.; Szafranski, P.; Cantor, C.R.

1998-05-19

442

Ozone and acid rain  

SciTech Connect

The roles of ozone and other oxidizing agents are discussed. The major polluting emissions are SO/sub 2/, NO, and volatile organic chemicals. In the usual ambient concentrations, these substances are relatively harmless. However, when SO/sub 2/ and NO are oxidized, they are converted into more acid, more toxic, substances. Oxidants, including OH, H/sub 2/O/sub 2/, HO/sub 2/, and organic peroxides, arise out of complex photochemistry that involves the ozone, the nitrogen oxides, and volatile organic chemicals. Were SO/sub 2/ the only pollutant, most of it would escape unchanged to the western Atlantic Ocean where it would be so diluted as to have no effect. At present about 35 percent of the SO/sub 2/ produced in the United States leaves the continent. In contrast, because of higher rates of reaction with oxidants, most of the NO is converted into nitric acid and deposited on land. The nitrogen oxides are involved in the production of ozone, some of which is naturally present. But particularly in urban settings where concentrations of NO/sub x/ are elevated and volatile organic chemicals such as those in gasoline are present, ozone concentrations may rise to levels deleterious to health. The Environmental Protection Agency has set standards for levels not to be exceeded, but nearly half of urban communities are not in compliance. The NO/sub x/ involved in the formation of urban ozone comes mostly from vehicular emissions.

Not Available

1987-10-09

443

46 CFR 151.50-77 - Fluorosilicic acid (30% or less) (hydrofluorosilicic acid).  

Code of Federal Regulations, 2010 CFR

...Fluorosilicic acid (30% or less) (hydrofluorosilicic acid). 151.50-77 Section 151...Fluorosilicic acid (30% or less) (hydrofluorosilicic acid). (a) Hydrofluorosilicic acid must be carried in gravity or...

2009-10-01

444

46 CFR 151.50-77 - Fluorosilicic acid (30% or less) (hydrofluorosilicic acid).  

Code of Federal Regulations, 2010 CFR

...Fluorosilicic acid (30% or less) (hydrofluorosilicic acid). 151.50-77 Section 151...Fluorosilicic acid (30% or less) (hydrofluorosilicic acid). (a) Hydrofluorosilicic acid must be carried in gravity or...

2010-10-01

445

Growth of nitric acid hydrates on thin sulfuric acid films  

NASA Astrophysics Data System (ADS)

Type I polar stratospheric clouds (PSCs) are thought to nucleate and grow on stratospheric sulfate aerosols (SSAs). To model this system, thin sulfuric acid films were exposed to water and nitric acid vapors (1 - 3 × 10-4 Torr H2O and 1 - 2.5 × 10-6 Torr HNO3) and subjected to cooling and heating cycles. FTIR spectroscopy was used to probe the phase of the sulfuric acid and to identify the HNO3/H2O films that condensed. Nitric acid trihydrate (NAT) was observed to grow on crystalline sulfuric acid tetrahydrate (SAT) films. NAT also condensed in/on supercooled H2SO4 films without causing crystallization of the sulfuric acid. This growth is consistent with NAT nucleation from ternary solutions as the first step in PSC formation.

Iraci, Laura T.; Middlebrook, Ann M.; Wilson, Margaret A.; Tolbert, Margaret A.

1994-05-01

446

Determination of benzoic acid, chlorobenzoic acids and chlorendic acid in water  

SciTech Connect

To characterize and conduct treatment studies of a landfill leachate an analysis procedure was required to determine concentrations of benzoic acid, the three isomers of chlorobenzoic acid and chlorendic acid. The title compounds were isolated from acidified (pH 1) water by extraction with methyl t-butyl ether. Analytes were concentrated by back-extracting the ether with 0.1 N sodium hydroxide which was separated and acidified. This solution was analyzed by C[sub 18] reversed-phase HPLC with water/acetonitrile/acetic acid eluent and UV detection at 222 nm. The method has detection limits of 200 [mu]g/L for chlorendic acid and 100 [mu]g/L for benzoic acid and each isomer of chlorobenzoic acid. Validation studies with water which was fortified with the analytes at concentrations ranging from one to ten times detection limits resulted in average recoveries of >95%.

Dietz, E.A.; Cortellucci, N.J.; Singley, K.F. (Occidental Chemical Corp., Grand Island, NY (United States))

1993-01-01

447

Acidizing: A well completion reference  

SciTech Connect

Acidizing removes near-wellbore formation damage by dissolving or bypassing drilling mud, completion fluid or other restrictions. These treatments include matrix pump rate jobs, washes and chemical injection. Matrix stimulation techniques are performed without fracturing reservoir rock. Acid is used to remove drilling, completion, workover or production damage. Solvents and surfactants like crude, condensate, diesel or mutual solvents are used to change pore fluid or formation wettability characteristics. Washes remove scale and other dispersible or soluble material from formations, perforations and casing. The purpose of the above methods is to improve well productivity by removing or mitigating formation damage. Hydrofluoric (HF) acid dissolves clay and fine particles in sandstones. Hydrochloric (HCl) acid etches wormholes that bypass damage in carbonates. Products are subdivided into groups that have similar function and performance. Where applicable, groups have been subdivided to reflect significant differences in additive chemical nature to emphasize uniqueness in the product lines of each company. Products and additives are grouped in 28 categories: water-base completion fluids; water-base polymers; friction reducers; fluid loss; diverting agents; polymer plugs; acid inhibitors; acid retarders; emulsifiers; clay stabilizers; surfactants; non-emulsifiers; fines suspender; anti-sludge agent; foamers; scale inhibitors; iron (Fe) control; oxygen scavenger; mutual solvents; corrosion inhibitors; paraffin control; miscellaneous products; acid systems; retarded acid system; mud acid plus surfactants; mud acid plus alcohol; SGMA; and retarded HF.

NONE

1997-11-01

448

Acid rain: Rhetoric and reality  

SciTech Connect

Acid rain is now one of the most serious environmental problems in developed countries. Emissions and fallout were previously extremely localized, but since the introduction of tall stacks policies in both Britain and the US - pardoxically to disperse particulate pollutants and hence reduce local damage - emissions are now lifted into the upper air currents and carried long distances downwind. The acid rain debate now embraces many western countries - including Canada, the US, England, Scotland, Wales, Sweden, Norway, Denmark, West Germany, the Netherlands, Austria, Switzerland - and a growing number of eastern countries - including the Soviet Union, Poland, East Germany, and Czechoslovakia. The problem of acid rain arises, strictly speaking, not so much from the rainfall itself as from its effects on the environment. Runoff affects surface water and groundwater, as well as soils and vegetation. Consequently changes in rainfall acidity can trigger off a range of impacts on the chemistry and ecology of lakes and rivers, soil chemistry and processes, the health and productivity of plants, and building materials, and metallic structures. The most suitable solutions to the problems of acid rain require prevention rather than cure, and there is broad agreement in both the political scientific communities on the need to reduce emissions of sulfur and nitrogen oxides to the atmosphere. Book divisions discuss: the problem of acid rain, the science of acid rain, the technology of acid rain, and the politics of acid rain, in an effort to evaluate this growing global problem of acid rain.

Park, C.C.

1987-01-01

449

Ultraviolet photodegradation of folic acid.  

PubMed

The vitamin folate is vital for all living creatures. Scientists have suggested that ultraviolet degradation of folate in vivo played a role in the evolution of mankind. In order to better understand the photodegradation of folate, we have provided a spectroscopic study of the ultraviolet photodegradation of aqueous folic acid under aerobic conditions. We found strong indications that the folic acid molecule is cleaved into p-aminobenzoyl-L-glutamic acid and 6-formyl pterin when exposed to ultraviolet radiation. When the irradiation continues, 6-formyl pterin is degraded to pterin-6-carboxylic acid. The photodegradation of folic acid is divided into three phases. In the first phase, the formation of photoproducts follows a zero order rate law. In the second phase the presence of photoproducts sensitizes the degradation of folic acid and the degradation process is accelerated. In the third phase the degradation of 6-formyl pterin to pterin-6-carboxylic acid is the dominating process. This reaction follows a first order rate law. We show that both 6-formyl pterin and pterin-6-carboxylic acid sensitize the photodegradation of folic acid. However, experiments performed in heavy water indicate that generation of singlet oxygen is probably not the explanation for the photosensitizing of folic acid. PMID:15963436

Off, Morten Kristian; Steindal, Arnfinn Engeset; Porojnicu, Alina Carmen; Juzeniene, Asta; Vorobey, Alexander; Johnsson, Anders; Moan, Johan

2005-04-13

450

Conversion of phenolics to lignans: Sinapic acid to thomasidioic acid  

Microsoft Academic Search

Changes in sinapic acid when exposed to aqueous alkaline conditions were elucidated. Sinapic acid was exposed to a volatile\\u000a buffer (pH 8.5) for 24 h, lyophilized, acidified, extracted, and characterized using nuclear magnetic resonance and mass spectroscopy.\\u000a The product obtained was identified as the lignan thomasidioic acid. This identification was confirmed by comparison with\\u000a a synthesized authentic sample of thomasidioic

M. I. Rubino; S. D. Arntfield; J. L. Charlton

1995-01-01

451