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1

Kinetics of bidirectional H+ and substrate transport by the proton-dependent amino acid symporter PAT1  

PubMed Central

PAT1 is a recently identified member of the PAT family of proton/amino acid co-transporters with predominant expression in the plasma membrane of enterocytes and in lysosomal membranes of neurons. Previous studies in Xenopus oocytes expressing PAT1 established proton/substrate co-transport associated with positive inward currents for a variety of small neutral amino acids. Here we provide a detailed analysis of the transport mode of the murine PAT1 in oocytes using the two-electrode voltage-clamp technique to measure steady-state and pre-steady-state currents. The GPC (giant patch clamp) technique and efflux studies were employed to characterize the reversed transport mode. Kinetic parameters [Km (Michaelis constant) and Imax (maximum current)] for transport of various substrates revealed a dependence on membrane potential: hyperpolarization increases the substrate affinity and maximal transport velocity. Proton affinity for interaction with PAT1 is almost 100 nM, corresponding to a pH of 7.0 and is independent of substrate. Kinetic analysis revealed that binding of proton most likely occurs before substrate binding and that the proton and substrate are translocated in a simultaneous step. No evidence for a substrate-uncoupled proton shunt was observed. As shown by efflux studies and current measurements by the GPC technique, PAT1 allows bidirectional amino acid transport. Surprisingly, PAT1 exhibits no pre-steady-state currents in the absence of substrate, even at low temperatures, and therefore PAT1 takes an exceptional position among the ion-coupled co-transporters. PMID:15504109

2004-01-01

2

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 PMID:8670886

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

3

Pat1 contributes to the RNA binding activity of the Lsm1-7-Pat1 complex.  

PubMed

A major mRNA decay pathway in eukaryotes is initiated by deadenylation followed by decapping of the oligoadenylated mRNAs and subsequent 5'-to-3' exonucleolytic degradation of the capless mRNA. In this pathway, decapping is a rate-limiting step that requires the hetero-octameric Lsm1-7-Pat1 complex to occur at normal rates in vivo. This complex is made up of the seven Sm-like proteins, Lsm1 through Lsm7, and the Pat1 protein. It binds RNA and has a unique binding preference for oligoadenylated RNAs over polyadenylated RNAs. Such binding ability is crucial for its mRNA decay function in vivo. In order to determine the contribution of Pat1 to the function of the Lsm1-7-Pat1 complex, we compared the RNA binding properties of the Lsm1-7 complex purified from pat1? cells and purified Pat1 fragments with that of the wild-type Lsm1-7-Pat1 complex. Our studies revealed that both the Lsm1-7 complex and purified Pat1 fragments have very low RNA binding activity and are impaired in the ability to recognize the oligo(A) tail on the RNA. However, reconstitution of the Lsm1-7-Pat1 complex from these components restored these abilities. We also observed that Pat1 directly contacts RNA in the context of the Lsm1-7-Pat1 complex. These studies suggest that the unique RNA binding properties and the mRNA decay function of the Lsm1-7-Pat1 complex involve cooperation of residues from both Pat1 and the Lsm1-7 ring. Finally our studies also revealed that the middle domain of Pat1 is essential for the interaction of Pat1 with the Lsm1-7 complex in vivo. PMID:25035297

Chowdhury, Ashis; Kalurupalle, Swathi; Tharun, Sundaresan

2014-09-01

4

Detection of Recurrent Thyroid Cancer by Sensitive Nested Reverse Transcription-Polymerase Chain Reaction of Thyroglobulin and Sodium\\/Iodide Symporter Messenger Ribonucleic Acid Transcripts in Peripheral Blood  

Microsoft Academic Search

To investigate whether circulating thyroglobulin (Tg) messenger ribonucleic acid (mRNA) and sodium\\/iodide symporter (NIS) mRNA transcripts in peripheral blood are valuable in the follow-up of pa- tients with thyroid cancer, we developed highly sensitive nested Tg and NIS mRNA detection assays and compared their accuracy with serum thyroglobulin (sTg) and whole body scan with 131I during the monitoring of 34

ROSA PAULA M. BISCOLLA; JANETE M. CERUTTI; RUI M. B. MACIEL

5

Intronic elements in the Na+/I- symporter gene (NIS) interact with retinoic acid receptors and mediate initiation of transcription  

PubMed Central

Activity of the sodium/iodide symporter (NIS) in lactating breast is essential for iodide (I–) accumulation in milk. Significant NIS upregulation was also reported in breast cancer, indicating a potential use of radioiodide treatment. All-trans-retinoic acid (tRA) is a potent ligand that enhances NIS expression in a subset of breast cancer cell lines and in experimental breast cancer models. Indirect tRA stimulation of NIS in breast cancer cells is very well documented; however, direct upregulation by tRA-activated nuclear receptors has not been identified yet. Aiming to uncover cis-acting elements directly regulating NIS expression, we screened evolutionary-conserved non-coding genomic sequences for responsiveness to tRA in MCF-7. Here, we report that a potent enhancer in the first intron of NIS mediates direct regulation by tRA-stimulated nuclear receptors. In vitro as well as in vivo DNA–protein interaction assays revealed direct association between retinoic acid receptor-? (RAR?) and retinoid-X-receptor (RXR) with this enhancer. Moreover, using chromatin immunoprecipitation (ChIP) we uncovered early events of NIS transcription in response to tRA, which require the interaction of several novel intronic tRA responsive elements. These findings indicate a complex interplay between nuclear receptors, RNA Pol-II and multiple intronic RAREs in NIS gene, and they establish a novel mechanistic model for tRA-induced gene transcription. PMID:20123735

Alotaibi, Hani; Yaman, Elif; Salvatore, Domenico; Di Dato, Valeria; Telkoparan, Pelin; Di Lauro, Roberto; Tazebay, Uygar H.

2010-01-01

6

DeltapH-Dependent Amino Acid Transport into Plasma Membrane Vesicles Isolated from Sugar Beet (Beta vulgaris L.) Leaves: II. Evidence for Multiple Aliphatic, Neutral Amino Acid Symports.  

PubMed

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 K(m) and K(i) 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 beta-carbon position that places a dense electron cloud close to the alpha-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. PMID:16668339

Li, Z C; Bush, D R

1991-08-01

7

Structural Integrity of Centromeric Chromatin and Faithful Chromosome Segregation Requires Pat1  

PubMed Central

The kinetochore (centromeric DNA and associated protein complex) is essential for faithful chromosome segregation and maintenance of genome stability. Here we report that an evolutionarily conserved protein Pat1 is a structural component of Saccharomyces cerevisiae kinetochore and associates with centromeres in a NDC10-dependent manner. Consistent with a role for Pat1 in kinetochore structure and function, a deletion of PAT1 results in delay in sister chromatid separation, errors in chromosome segregation, and defects in structural integrity of centromeric chromatin. Pat1 is involved in topological regulation of minichromosomes as altered patterns of DNA supercoiling were observed in pat1? cells. Studies with pat1 alleles uncovered an evolutionarily conserved region within the central domain of Pat1 that is required for its association with centromeres, sister chromatid separation, and faithful chromosome segregation. Taken together, our data have uncovered a novel role for Pat1 in maintaining the structural integrity of centromeric chromatin to facilitate faithful chromosome segregation and proper kinetochore function. PMID:23893485

Mishra, Prashant K.; Ottmann, Alicia R.; Basrai, Munira A.

2013-01-01

8

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. PMID:23851565

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

2013-01-01

9

Synchronized fission yeast meiosis using an ATP analog-sensitive Pat1 protein kinase  

PubMed Central

Synchronous cultures are often indispensable for studying meiosis. Here, we present an optimized protocol for induction of synchronous meiosis in the fission yeast Schizosaccharomyces pombe. Chemical inactivation of an ATP analog-sensitive form of the Pat1 kinase (pat1-as2) by adding the ATP-analog 1-NM-PP1 in G1-arrested cells allows induction of synchronous meiosis at optimal temperature (25 °C). Importantly, this protocol eliminates detrimental effects of elevated temperature (34 °C) which is required to inactivate the commonly used temperature-sensitive Pat1 kinase mutant (pat1-114). Addition of the mat-Pc gene to a mat1-M strain further improves chromosome segregation and spore viability. Thus, our protocol offers highly synchronous meiosis at optimal temperature with most characteristics similar to those of wild-type meiosis. The synchronization protocol can be completed in 5 days. PMID:24385151

Cipak, Lubos; Polakova, Silvia; Hyppa, Randy W.; Smith, Gerald R.; Gregan, Juraj

2014-01-01

10

Cooperation of histone deacetylase inhibitors SAHA and valproic acid in promoting sodium/iodide symporter expression and function in rat Leydig testicular carcinoma cells.  

PubMed

The presence of the sodium/iodide symporter (NIS) is the prerequisite for the use of the radioiodine in the treatment of thyroid cancer. Thus, stimulators of NIS expression and function are currently investigated in cellular models of various human malignancies, also including extrathyroid cancers. In this study, we analyzed the effects of the histone deacetylase inhibitors (HDACi), suberoylanilide hydroxamic acid (SAHA) and valproic acid (VPA), on NIS expression and function in rat Leydig testicular carcinoma cells (LC540). LC540 cells were exposed to SAHA 3 ?M and VPA 3 mM (alone and in combination), and cell viability evaluated by MTT assay and cell counting, NIS mRNA and protein levels by using, respectively, real-time RT-PCR and western blotting. NIS function was evaluated by iodide uptake assay. We found that both HDACi were able to stimulate the transcription of NIS gene, but not its protein expression, while the association of SAHA and VPA increased both NIS transcript and protein levels, resulting in significant sixfold enhancement of radioiodine uptake capacity of LC540 cells. These data demonstrate the presence of an epigenetic control of NIS expression in Leydig tumor cells, suggesting the possibility to use the combination of these two HDACi for a radioiodine-based treatment of these malignancies. PMID:23636804

Maggisano, V; Puppin, C; Celano, M; D'Agostino, M; Sponziello, M; Micali, S; Navarra, M; Damante, G; Filetti, S; Russo, D

2014-02-01

11

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

12

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. PMID:21712243

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

13

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

PubMed

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. PMID:21712243

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

2011-09-01

14

PAT1a modulates intracellular transport and processing of amyloid precursor protein (APP), APLP1, and APLP2.  

PubMed

Understanding the intracellular transport of the beta-amyloid precursor protein (APP) is a major key to elucidate the regulation of APP processing and thus beta-amyloid peptide generation in Alzheimer disease pathogenesis. APP and its two paralogues, APLP1 and APLP2 (APLPs), are processed in a very similar manner by the same protease activities. A putative candidate involved in APP transport is protein interacting with APP tail 1 (PAT1), which was reported to interact with the APP intracellular domain. We show that PAT1a, which is 99.0% identical to PAT1, binds to APP, APLP1, and APLP2 in vivo and describe their co-localization in trans-Golgi network vesicles or endosomes in primary neurons. We further demonstrate a direct interaction of PAT1a with the basolateral sorting signal of APP/APLPs. Moreover, we provide evidence for a direct role of PAT1a in APP/APLP transport as overexpression or RNA interference-mediated knockdown of PAT1a modulates APP/APLPs levels at the cell surface. Finally, we show that PAT1a promotes APP/APLPs processing, resulting in increased secretion of beta-amyloid peptide. Taken together, our data establish PAT1a as a functional link between APP/APLPs transport and their processing. PMID:17050537

Kuan, Yung-Hui; Gruebl, Tomas; Soba, Peter; Eggert, Simone; Nesic, Iva; Back, Simone; Kirsch, Joachim; Beyreuther, Konrad; Kins, Stefan

2006-12-29

15

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

16

The Pot1a-associated proteins Tpt1 and Pat1 coordinate telomere protection and length regulation in Tetrahymena.  

PubMed

We have identified two new telomere proteins, Tpt1 and Pat1, from the ciliate Tetrahymena thermophila. Although Tetrahymena telomerase is well characterized, only one telomere protein had previously been identified. This was the G-overhang binding-protein Pot1a. Tpt1 and Pat1 were isolated as Pot1a binding partners and shown to localize to telomeres. As Tpt1 and Pat1 were both found to be essential, conditional cell lines were generated to explore their function. Tpt1 depletion caused a rapid growth arrest and telomere elongation in the absence of cell division. The phenotype was similar to that seen after Pot1a depletion suggesting that Tpt1 and Pot1a function together to regulate telomere length and prevent telomere deprotection. In contrast, Pat1 depletion had a modest effect on cell growth but caused progressive telomere shortening similar to that observed upon TERT depletion. Thus Pat1 appears to be needed for telomerase to maintain the chromosome terminus. Analysis of Pot1a-Tpt1-Pat1 complex formation using purified proteins indicated that Tpt1 interacts directly with Pot1a while Pat1 interacts with Tpt1. Our results indicate that Tpt1 is the Tetrahymena equivalent of mammalian TPP1, Schizosaccharomyces pombe Tpz1, and Oxytricha nova TEBP?. PMID:21900503

Linger, Benjamin R; Morin, Gregg B; Price, Carolyn M

2011-11-01

17

Lsm2 and Lsm3 bridge the interaction of the Lsm1-7 complex with Pat1 for decapping activation  

PubMed Central

The evolutionarily conserved Lsm1-7-Pat1 complex is the most critical activator of mRNA decapping in eukaryotic cells and plays many roles in normal decay, AU-rich element-mediated decay, and miRNA silencing, yet how Pat1 interacts with the Lsm1-7 complex is unknown. Here, we show that Lsm2 and Lsm3 bridge the interaction between the C-terminus of Pat1 (Pat1C) and the Lsm1-7 complex. The Lsm2-3-Pat1C complex and the Lsm1-7-Pat1C complex stimulate decapping in vitro to a similar extent and exhibit similar RNA-binding preference. The crystal structure of the Lsm2-3-Pat1C complex shows that Pat1C binds to Lsm2-3 to form an asymmetric complex with three Pat1C molecules surrounding a heptameric ring formed by Lsm2-3. Structure-based mutagenesis revealed the importance of Lsm2-3-Pat1C interactions in decapping activation in vivo. Based on the structure of Lsm2-3-Pat1C, a model of Lsm1-7-Pat1 complex is constructed and how RNA binds to this complex is discussed. PMID:24247251

Wu, Donghui; Muhlrad, Denise; Bowler, Matthew W; Jiang, Shimin; Liu, Zhou; Parker, Roy; Song, Haiwei

2014-01-01

18

Thyroid Na /I Symporter MECHANISM, STOICHIOMETRY, AND SPECIFICITY*  

E-print Network

Thyroid Na /I Symporter MECHANISM, STOICHIOMETRY, AND SPECIFICITY* (Received for publication, May College of Medicine, Bronx, New York 10461 The rat thyroid Na /I symporter (NIS) was expressed in Xenopus. It is now firmly established that active accumulation of io- dide (I ) by the thyroid gland epithelium

Eskandari, Sepehr

19

Structure and Function of Na+-Symporters with Inverted Repeats  

PubMed Central

Summary Symporters are membrane proteins that couple energy stored in electrochemical potential gradients to drive the cotransport of molecules and ions into cells. Traditionally, proteins are classified into gene families based on sequence homology and functional properties, e.g. the sodium glucose (SLC5 or Sodium Solute Symporter Family, SSS or SSF) and GABA (SLC6 or Neurotransmitter Sodium Symporter Family, NSS or SNF) symporter families [1-4]. Recently, it has been established that four Na+-symporter proteins with unrelated sequences have a common structural core containing an inverted repeat of 5 transmembrane (TM) helices [5-8]. Analysis of these four structures reveals that they reside in different conformations along the transport cycle providing atomic insight into the mechanism of sodium solute cotransport. PMID:19631523

Abramson, Jeff; Wright, Ernest M.

2009-01-01

20

Characterization of new polyol/H+ symporters in Debaryomyces hansenii.  

PubMed

Debaryomyces hansenii is a halotolerant yeast that produces and assimilates a wide variety of polyols. In this work we evaluate polyol transport in D. hansenii CBS 767, detecting the occurrence of polyol/H(+) (and sugar/H(+)) symporter activity, through the transient extracellular alkalinization of unbuffered starved cell suspensions. From the D. hansenii genome database, we selected nine ORFs encoding putative transporter proteins to clone in a centromeric plasmid with C-terminal GFP tagging and screened for polyol/H(+) symporters by heterologous expression in Saccharomyces cerevisiae. Five distinct D. hansenii polyol/H(+) symporters were identified and characterized, with different specificities and affinities for polyols, namely one glycerol-specific (DhStl1), one D-galactitol-specific (DhSgl1, Symporter galactitol/H(+) 1), one D-(+)-chiro-inositol-specific (DhSyi1, Symporter D-(+)-chiro-inositol/H(+) 1), one for D-sorbitol/D-mannitol/ribitol/D-arabitol/D-galactitol (DhSyl1, Symporter Polyols 1) and another for D-sorbitol/D-mannitol/ribitol/D-arabitol (DhSyl2, Symporter Polyols 2). This work contributed to the annotation of new yeast polyol transporters, including two specific for uncommon substrates as galactitol and D-(+)-chiro-inositol. PMID:24505419

Pereira, Iliana; Madeira, Ana; Prista, Catarina; Loureiro-Dias, Maria C; Leandro, Maria José

2014-01-01

21

The conserved P body component HPat/Pat1 negatively regulates synaptic terminal growth at the larval Drosophila neuromuscular junction.  

PubMed

The temporal and spatial regulation of protein synthesis plays an important role in the control of neural physiology. In axons and dendrites, translationally repressed mRNAs are actively transported to their destinations in a variety of ribonucleoprotein particles (RNPs). A subset of these neuronal RNPs has been shown to contain proteins associated with mRNA processing bodies (P bodies). P bodies are a class of highly conserved cytoplasmic granules that have been linked to both mRNA decay and translational repression via general and miRNA-mediated pathways. Here, we characterize functions for HPat/Pat1 (also known as Patr-1), a core component of P bodies, at the glutamatergic larval Drosophila neuromuscular junction (NMJ). We show that hpat mutants exhibit a strong synaptic hyperplasia at the NMJ. The synaptic defects observed in hpat mutants are associated with rearrangement of the axonal microtubule cytoskeleton suggesting that HPat negatively regulates presynaptic microtubule-based growth during NMJ development. Consistent with this, overexpression of HPat also blocks the rapid growth of presynaptic boutons induced by spaced depolarization. Finally, we demonstrate that HPat interacts genetically with the catalytic subunit of the deadenylase complex (twin/CCR4) and the miRNA pathway (Argonaute 1) to control bouton formation. We propose that HPat is required to target mRNAs involved in the control of microtubule architecture and synaptic terminal growth for repression, presumably in P bodies, via both general and miRNA-mediated mechanisms. PMID:23097047

Pradhan, Sarala J; Nesler, Katherine R; Rosen, Sarah F; Kato, Yasuko; Nakamura, Akira; Ramaswami, Mani; Barbee, Scott A

2012-12-15

22

Structure-based mechanism for Na+/melibiose symport by MelB  

PubMed Central

The bacterial melibiose permease (MelB) belongs to the glycoside–pentoside–hexuronide:cation symporter family, a part of the major facilitator superfamily (MFS). Structural information regarding glycoside–pentoside–hexuronide:cation symporter family transporters and other Na+-coupled permeases within MFS has been lacking, although a wealth of biochemical and biophysical data are available. Here we present the three-dimensional crystal structures of Salmonella typhimurium MelBSt in two conformations, representing an outward partially occluded and an outward inactive state of MelBSt. MelB adopts a typical MFS fold and contains a previously unidentified cation-binding motif. Three conserved acidic residues form a pyramidal-shaped cation-binding site for Na+, Li+ or H+, which is in close proximity to the sugar-binding site. Both cosubstrate-binding sites are mainly contributed by the residues from the amino-terminal domain. These two structures and the functional data presented here provide mechanistic insights into Na+/melibiose symport. We also postulate a structural foundation for the conformational cycling necessary for transport catalysed by MFS permeases in general. PMID:24389923

Ethayathulla, Abdul S.; Yousef, Mohammad S.; Amin, Anowarul; Leblanc, Gerard; Kaback, H. Ronald; Guan, Lan

2014-01-01

23

The sodium/iodide symporter: state of the art of its molecular characterization.  

PubMed

The sodium/iodide symporter (NIS or SLC5A5) is an intrinsic membrane protein implicated in iodide uptake into thyroid follicular cells. It plays a crucial role in iodine metabolism and thyroid regulation and its function is widely exploited in the diagnosis and treatment of benign and malignant thyroid diseases. A great effort is currently being made to develop a NIS-based gene therapy also allowing the radiotreatment of nonthyroidal tumors. NIS is also expressed in other tissues, such as salivary gland, stomach and mammary gland during lactation, where its physiological role remains unclear. The molecular identity of the thyroid iodide transporter was elucidated approximately fifteen years ago. It belongs to the superfamily of sodium/solute symporters, SSS (and to the human transporter family, SLC5), and is composed of 13 transmembrane helices and 643 amino acid residues in humans. Knowledge concerning NIS structure/function relationship has been obtained by taking advantage of the high resolution structure of one member of the SSS family, the Vibrio parahaemolyticus sodium/galactose symporter (vSGLT), and from studies of gene mutations leading to congenital iodine transport defects (ITD). This review will summarize current knowledge regarding the molecular characterization of NIS. PMID:23988430

Darrouzet, Elisabeth; Lindenthal, Sabine; Marcellin, Didier; Pellequer, Jean-Luc; Pourcher, Thierry

2014-01-01

24

Iodide symporter gene expression in human thyroid tumors.  

PubMed

Expression of the Na+/I- symporter (NIS) gene was investigated by RT-PCR in a selected series of 26 primary thyroid carcinomas (19 papillary, 5 follicular, and 2 anaplastic). Fifteen follicular adenomas (11 "cold" and 4 "hot" adenomas) were also studied. Five of 19 papillary thyroid cancer did not express NIS messenger ribonucleic acid (mRNA). In all but 1 follicular cancer, NIS transcript was fully detected. In anaplastic tissue, NIS mRNA was only barely detected in 1 case. All of the follicular thyroid adenomas except 1 expressed the NIS gene. In contrast, all tumors studied excluding the anaplastic histotype fully expressed thyroglobulin and thyroid peroxidase mRNA transcripts. In 2 patients, a lower expression (3- to 5-fold) of NIS mRNA was found in metastasis by dot blot analysis compared with those in both normal and primary neoplastic thyroid tissue. Four of 8 differentiated thyroid cancer patients selected for the presence of metastases with negative posttherapy 131I total body scan showed the lack of NIS gene expression in their primary cancer. This defect, at least in these cases, is a somatic and intrinsic lesion of the primary cancer cells and is not due to a dedifferentiation process in the metastatic tissue. The early detection of the loss of NIS gene expression in the primary cancer, therefore, may provide useful information for the management of differentiated thyroid cancer patients. PMID:9661633

Arturi, F; Russo, D; Schlumberger, M; du Villard, J A; Caillou, B; Vigneri, P; Wicker, R; Chiefari, E; Suarez, H G; Filetti, S

1998-07-01

25

Molecular Cloning and Functional Expression in Lactobacillus plantarum 80 of xylT, Encoding the D-Xylose-H 1 Symporter of Lactobacillus brevis  

Microsoft Academic Search

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 1 symporters of E. coli, XylE (57%),

STEPHANE CHAILLOU; YEOU-CHERNG BOR; CARL A. BATT; PIETER W. POSTMA; PETER H. POUWELS

1998-01-01

26

PvAMT1;1, a Highly Selective Ammonium Transporter That Functions as H+/NH4+ Symporter*  

PubMed Central

One of the main forms of nitrogen assimilated by microorganisms and plants is ammonium, despite its toxicity at low millimolar concentrations. Ammonium absorption has been demonstrated to be carried out by highly selective plasma membrane-located transporters of the AMT/MEP/Rh family and characterized by the presence of a well conserved hydrophobic pore through which ammonia is proposed to move. However, uncertainties exist regarding the exact chemical species transported by these membrane proteins, which can be in the form of either hydrophobic ammonia or charged ammonium. Here, we present the characterization of PvAMT1;1 from the common bean and demonstrate that it mediates the high affinity (micromolar), rapidly saturating (1 mm) electrogenic transport of ammonium. Activity of the transporter is enhanced by low extracellular pH, and associated with this acidic pH stimulation are changes in the reversal potential and cytoplasm acidification, indicating that PvAMT1;1 functions as an H+/NH4+ symporter. Mutation analysis of a unique histidine present in PvAMT1;1 (H125R) leads to the stimulation of ammonium transport by decreasing the Km value by half and by increasing the Vmax 3-fold, without affecting the pH dependence of the symporter. In contrast, mutation of the first conserved histidine within the channel modifies the properties of PvAMT1;1, increasing its Km and Vmax values and transforming it into a pH-independent mechanism. PMID:21757699

Ortiz-Ramirez, Carlos; Mora, Silvia I.; Trejo, Jorge; Pantoja, Omar

2011-01-01

27

Sodium Solute Symporter and Cadherin Proteins Act as Bacillus thuringiensis Cry3Ba Toxin Functional Receptors in Tribolium castaneum*  

PubMed Central

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

2013-01-01

28

Crystal structure of a glucose/H+ symporter and its mechanism of action  

PubMed Central

Glucose transporters are required to bring glucose into cells, where it is an essential energy source and precursor in protein and lipid synthesis. These transporters are involved in important common diseases such as cancer and diabetes. Here, we report the crystal structure of the Staphylococcus epidermidis glucose/H+ symporter in an inward-facing conformation at 3.2-Å resolution. The Staphylococcus epidermidis glucose/H+ symporter is homologous to human glucose transporters, is very specific and has high avidity for glucose, and is inhibited by the human glucose transport inhibitors cytochalasin B, phloretin, and forskolin. On the basis of the crystal structure in conjunction with mutagenesis and functional studies, we propose a mechanism for glucose/H+ symport and discuss the symport mechanism versus facilitated diffusion. PMID:24127585

Iancu, Cristina V.; Zamoon, Jamillah; Woo, Sang Bum; Aleshin, Alexander; Choe, Jun-yong

2013-01-01

29

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

30

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

PubMed

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 protein abundance, both in vitro and in vivo. However, other factors, including iodide, retinoic acid, transforming growth factor-beta, interleukin-1alpha and tumour necrosis factor alpha, may participate in the regulation of NIS expression. Investigation of NIS mRNA expression in different thyroid tissues has revealed increased levels of expression in Graves' disease and toxic adenomas, whereas a reduction or loss of NIS transcript was detected in differentiated thyroid carcinomas, despite the expression of other specific thyroid markers. NIS mRNA was also detected in non-thyroid tissues able to concentrate radioiodine, including salivary glands, stomach, thymus and breast. The production of specific antibodies against the NIS has facilitated study of the expression of the symporter protein. Despite of the presence of high levels of human (h)NIS mRNA, normal thyroid glands exhibit a heterogeneous expression of NIS protein, limited to the basolateral membrane of the thyrocytes. By immunohistochemistry, staining of hNIS protein was stronger in Graves' and toxic adenomas and reduced in thyroid carcinomas. Measurement of iodide uptake by thyroid cancer cells is the cornerstone of the follow-up and treatment of patients with thyroid cancer. However, radioiodide uptake is found only in about 67% of patients with persistent or recurrent disease. Several studies have demonstrated a decrease in or a loss of NIS expression in primary human thyroid carcinomas, and immunohistochemical studies have confirmed this considerably decreased expression of the NIS protein in thyroid cancer tissues, suggesting that the low expression of NIS may represent an early abnormality in the pathway of thyroid cell transformation, rather than being a consequence of cancer progression. The relationship between radioiodine uptake and NIS expression by thyroid cancer cells require further study. New strategies, based on manipulation of NIS expression, to obtain NIS gene reactivation or for use as NIS gene therapy in the treatment of radiosensitive cancer, are also being investigated. PMID:10576759

Filetti, S; Bidart, J M; Arturi, F; Caillou, B; Russo, D; Schlumberger, M

1999-11-01

31

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. PMID:22750642

Kogai, Takahiko; Brent, Gregory A.

2012-01-01

32

Increased expression of the sodium/iodide symporter in papillary thyroid carcinomas.  

PubMed Central

Iodide is concentrated to a much lesser extent by papillary thyroid carcinoma as compared with the normal gland. The Na+/I- symporter (NIS) is primarily responsible for the uptake of iodide into thyroid cells. Our objective was to compare NIS mRNA and protein expression in papillary carcinomas with those in specimens with normal thyroid. Northern blot analysis revealed a 2.8-fold increase in the level of NIS mRNA in specimens with papillary carcinoma versus specimens with normal thyroid. Immunoblot analysis using anti-human NIS antibody that was produced with a glutathione S-transferase fusion protein containing NIS protein (amino acids 466-522) showed the NIS protein at 77 kD. The NIS protein level was elevated in 7 of 17 cases of papillary carcinoma but was not elevated in the normal thyroid. Immunohistochemical staining revealed abundant NIS in 8 of 12 carcinomas, whereas NIS protein was barely detected in specimens with normal thyroid. Although considerable patient-to-patient variation was observed, our results indicate that NIS mRNA is elevated, and its protein tends to be more abundant, in a subset of papillary thyroid carcinomas than in normal thyroid tissue. PMID:9525971

Saito, T; Endo, T; Kawaguchi, A; Ikeda, M; Katoh, R; Kawaoi, A; Muramatsu, A; Onaya, T

1998-01-01

33

Modulation of sodium iodide symporter in thyroid cancer.  

PubMed

Radioactive iodine (RAI) is a key therapeutic modality for thyroid cancer. Loss of RAI uptake in thyroid cancer inversely correlates with patient's survival. In this review, we focus on the challenges encountered in delivering sufficient doses of I-131 to eradicate metastatic lesions without increasing the risk of unwanted side effects. Sodium iodide symporter (NIS) mediates iodide influx, and NIS expression and function can be selectively enhanced in thyroid cells by thyroid-stimulating hormone. We summarize our current knowledge of NIS modulation in normal and cancer thyroid cells, and we propose that several reagents evaluated in clinical trials for other diseases can be used to restore or further increase RAI accumulation in thyroid cancer. Once validated in preclinical mouse models and clinical trials, these reagents, mostly small-molecule inhibitors, can be readily translated into clinical practice. We review available genetically engineered mouse models of thyroid cancer in terms of their tumor development and progression as well as their thyroid function. These mice will not only provide important insights into the mechanisms underlying the loss of RAI uptake in thyroid tumors but will also serve as preclinical animal models to evaluate the efficacy of candidate reagents to selectively increase RAI uptake in thyroid cancers. Taken together, we anticipate that the optimal use of RAI in the clinical management of thyroid cancer is yet to come in the near future. PMID:25234361

Lakshmanan, Aparna; Scarberry, Daniel; Shen, Daniel H; Jhiang, Sissy M

2014-12-01

34

A potassium-proton symport in Neurospora crassa  

PubMed Central

Combined ion flux and electrophysiological measurements have been used to characterized active transport of potassium by cells of Neurospora crassa that have been moderately starved of K+ and then maintained in the presence of millimolar free calcium ions. These conditions elicit a high-affinity (K1/2 = 1-10 microM) potassium uptake system that is strongly depolarizing. Current-voltage measurements have demonstrated a K+-associated inward current exceeding (at saturation) half the total current normally driven outward through the plasma membrane proton pump. Potassium activity ratios and fluxes have been compared quantitatively with electrophysiological parameters, by using small (approximately 15 micron diam) spherical cells of Neurospora grown in ethylene glycol. All data are consistent with a transport mechanism that carries K ions inward by cotransport with H ions, which move down the electrochemical gradient created by the primary proton pump. The stoichiometry of entry is 1 K ion with 1 H ion; overall charge balance is maintained by pumped extrusion of two protons, to yield a net flux stoichiometry of 1 K+ exchanging for 1 H+. The mechanism is competent to sustain the largest stable K+ gradients that have been measured in Neurospora, with no direct contribution from phosphate hydrolysis or redox processes. Such a potassium-proton symport mechanism could account for many observations reported on K+ movement in other fungi, in algae, and in higher plants. PMID:3014042

1986-01-01

35

Absence of sodium/iodide symporter gene mutations in differentiated human thyroid carcinomas.  

PubMed

Decrease or loss of the sodium iodide (Na+/I-) symporter (NIS) activity influences the suitability of using radioiodine to detect and treat metastatic thyroid tissues. In previous studies, the presence of the NIS transcript, albeit at lower expression levels, has been shown in most thyroid differentiated carcinomas. In this study we searched for point mutations or other genetic alterations that may be responsible for an altered function of the NIS protein in tumors that still express NIS transcripts. Tumoral cDNAs derived from seven differentiated thyroid carcinomas (DTC), five papillary and two follicular, were analyzed by direct sequencing after polymerase chain reaction (PCR) amplification of the structural gene of the Na+/I- symporter. Neither mutations nor other genetic abnormalities were detected in any tumor sample examined. The data indicate that mutations or other genetic alterations of the NIS structural gene are not a major cause of the reduced iodide uptake in DTC. PMID:11272095

Russo, D; Manole, D; Arturi, F; Suarez, H G; Schlumberger, M; Filetti, S; Derwahl, M

2001-01-01

36

Resveratrol Inhibits Sodium/Iodide Symporter Gene Expression and Function in Rat Thyroid Cells  

PubMed Central

Resveratrol is a polyphenol found in grapes and berries that has antioxidant, antiproliferative and anti-inflammatory properties. For these reasons, it is available as a dietary supplement, and it is under investigation in several clinical trials. Few data are available regarding the effects of resveratrol on thyroid function. A previous study showed that resveratrol transiently increases iodide influx in FRTL-5 rat thyroid cells. Indeed, this increase arises after short treatment times (6–12 h), and no further effects are seen after 24 h. The aim of the present study was to investigate the effects of resveratrol on iodide uptake and sodium/iodide symporter expression in thyroid cells after longer times of treatment. For this purpose, the effects of resveratrol were evaluated both in vitro and in vivo using the rat thyroid FRTL-5 cell line and Sprague-Dawley rats, respectively. In FRTL-5 cells, resveratrol decreased the sodium/iodide symporter RNA and protein expression as a function of time. Furthermore, resveratrol decreased cellular iodide uptake after 48 h of treatment. The inhibitory effect of resveratrol on iodide uptake was confirmed in vivo in Sprague-Dawley rats. This study demonstrates that with longer-term treatment, resveratrol is an inhibitor of sodium/iodide symporter gene expression and function in the thyroid. These data suggest that resveratrol can act as a thyroid disruptor, which indicates the need for caution as a supplement and in therapeutic use. PMID:25251397

Giuliani, Cesidio; Bucci, Ines; Di Santo, Serena; Rossi, Cosmo; Grassadonia, Antonino; Mariotti, Marianna; Piantelli, Mauro; Monaco, Fabrizio; Napolitano, Giorgio

2014-01-01

37

Molecular cloning and functional expression in lactobacillus plantarum 80 of xylT, encoding the D-xylose-H+ symporter of Lactobacillus brevis.  

PubMed

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 microM, 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 microM. PMID:9835554

Chaillou, S; Bor, Y C; Batt, C A; Postma, P W; Pouwels, P H

1998-12-01

38

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. PMID:9835554

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

1998-01-01

39

Cloning of a functional promoter of the human sodium/iodide-symporter gene.  

PubMed Central

We have cloned and sequenced genomic DNA from a human library extending 1300 bp upstream the 5'-untranslated sequence of the cDNA coding for the sodium/iodide symporter. In transient transfection assays this sequence exhibited promoter activity, which could be confined to nucleotides -443 to -395 relative to the ATG start codon. This minimal promoter, including a putative GC- and TATA- box, was preferentially activated in the rat thyroid cell line FRTL-5, but was also active in non-thyroidal cells, such as COS-7 and Chinese-hamster ovary, albeit to a markedly lower extent. PMID:9531470

Behr, M; Schmitt, T L; Espinoza, C R; Loos, U

1998-01-01

40

MEK inhibition leads to lysosome-mediated Na+/I- symporter protein degradation in human breast cancer cells.  

PubMed

The Na(+)/I(-) symporter (NIS (SLC5A5)) is a transmembrane glycoprotein that mediates active iodide uptake into thyroid follicular cells. NIS-mediated iodide uptake in thyroid cells is the basis for targeted radionuclide imaging and treatment of differentiated thyroid carcinomas and their metastases. Furthermore, NIS is expressed in many human breast tumors but not in normal non-lactating breast tissue, suggesting that NIS-mediated radionuclide uptake may also allow the imaging and targeted therapy of breast cancer. However, functional cell surface NIS expression is often low in breast cancer, making it important to uncover signaling pathways that modulate NIS expression at multiple levels, from gene transcription to posttranslational processing and cell surface trafficking. In this study, we investigated NIS regulation in breast cancer by MAPK/extracellular signal-regulated kinase (ERK) kinase (MEK) signaling, an important cell signaling pathway involved in oncogenic transformation. We found that MEK inhibition decreased NIS protein levels in all-trans retinoic acid/hydrocortisone-treated MCF-7 cells as well as human breast cancer cells expressing exogenous NIS. The decrease in NIS protein levels by MEK inhibition was not accompanied by a decrease in NIS mRNA or a decrease in NIS mRNA export from the nucleus to the cytoplasm. NIS protein degradation upon MEK inhibition was prevented by lysosome inhibitors but not by proteasome inhibitors. Interestingly, NIS protein level was correlated with MEK/ERK activation in human breast tumors from a tissue microarray. Taken together, MEK activation appears to play an important role in maintaining NIS protein stability in human breast cancers. PMID:23404856

Zhang, Zhaoxia; Beyer, Sasha; Jhiang, Sissy M

2013-04-01

41

MEK Inhibition Leads To Lysosome-Mediated Na+/I- Symporter Protein Degradation In Human Breast Cancer Cells  

PubMed Central

The Na+/I- symporter (NIS) is a transmembrane glycoprotein that mediates active iodide uptake into thyroid follicular cells. NIS-mediated iodide uptake in thyroid cells is the basis for targeted radionuclide imaging and treatment of differentiated thyroid carcinomas and their metastases. Furthermore, NIS is expressed in many human breast tumors but not in normal non-lactating breast tissue, suggesting that NIS-mediated radionuclide uptake may also allow the imaging and targeted therapy of breast cancer. However, functional cell surface NIS expression is often low in breast cancer, making it important to uncover signaling pathways that modulate NIS expression at multiple levels, from gene transcription to post-translational processing and cell surface trafficking. In this study, we investigated NIS regulation in breast cancer by MEK (MAPK/ERK kinase) signaling, an important cell signaling pathway involved in oncogenic transformation. We found that MEK inhibition decreased NIS protein levels in all-trans retinoic acid (tRA)/hydrocortisone treated MCF-7 cells as well as human breast cancer cells expressing exogenous NIS. The decrease in NIS protein levels by MEK inhibition was not accompanied by a decrease in NIS mRNA or a decrease in NIS mRNA export from the nucleus to the cytoplasm. NIS protein degradation upon MEK inhibition was prevented by lysosome inhibitors, but not by proteasome inhibitors. Interestingly, NIS protein level was correlated with MEK/ERK activation in human breast tumors from a tissue microarray. Taken together, MEK activation appears to play an important role in maintaining NIS protein stability in human breast cancers. PMID:23404856

Zhang, Zhaoxia; Beyer, Sasha; Jhiang, Sissy M

2013-01-01

42

A member of the sugar transporter family, Stl1p is the glycerol/H+ symporter in Saccharomyces cerevisiae.  

PubMed

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. PMID:15703210

Ferreira, Célia; van Voorst, Frank; Martins, António; Neves, Luisa; Oliveira, Rui; Kielland-Brandt, Morten C; Lucas, Cândida; Brandt, Anders

2005-04-01

43

ZrFsy1, a High-Affinity Fructose/H+ Symporter from Fructophilic Yeast Zygosaccharomyces rouxii  

PubMed Central

Zygosaccharomyces rouxii is a fructophilic yeast than can grow at very high sugar concentrations. We have identified an ORF encoding a putative fructose/H+ symporter in the Z. rouxii CBS 732 genome database. Heterologous expression of this ORF in a S. cerevisiae strain lacking its own hexose transporters (hxt-null) and subsequent kinetic characterization of its sugar transport activity showed it is a high-affinity low-capacity fructose/H+ symporter, with Km 0.45±0.07 mM and Vmax 0.57±0.02 mmol h?1 (gdw) ?1. We named it ZrFsy1. This protein also weakly transports xylitol and sorbose, but not glucose or other hexoses. The expression of ZrFSY1 in Z. rouxii is higher when the cells are cultivated at extremely low fructose concentrations (<0.2%) and on non-fermentable carbon sources such as mannitol and xylitol, where the cells have a prolonged lag phase, longer duplication times and change their microscopic morphology. A clear phenotype was determined for the first time for the deletion of a fructose/H+ symporter in the genome where it occurs naturally. The effect of the deletion of ZrFSY1 in Z. rouxii cells is only evident when the cells are cultivated at very low fructose concentrations, when the ZrFsy1 fructose symporter is the main active fructose transporter system. PMID:23844167

Leandro, Maria Jose; Sychrova, Hana; Prista, Catarina; Loureiro-Dias, Maria C.

2013-01-01

44

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

45

The sodium-iodine symporter and the proton-pump inhibitors in - related to the side effects of- the treatment of thyroid cancer with iodine-131.  

PubMed

Iodine-131 ((131)I) administered to patients for imaging or treatment, concentrates in the gastrointestinal tract, including the salivary glands, stomach and bowel. In Nuclear Medicine practice this biological property of iodine causes side effects when the therapeutic dose of (131)I is large. This occurs during the treatment of patients with differentiated thyroid carcinoma (DTC). During this clinical application, the dose of (131)I is higher than 3.7 GBq. Side effects of this treatment with respect to the stomach, include gastritis as an inflammatory reaction to radiation, anorexia due to gastric atrophy and rarely megaloblastic anemia due to lack of the endogenous factor. Side effects can also include xerostomia. We have recently tried to prevent gastric side effects by prescribing proton pump inhibitors (PPI) for patients with DTC prior to treatment with (131)I. PPI block the excretion of hydrochloric acid from the gastric mucosa and are utilized for the prevention and treatment of gastritis, gastric ulcers and gastroesophageal reflux. Whole body scans before or after the administration of PPI, showed that PPI do not interfere with the biologic distribution of (131)I. These findings were not surprising. Recent studies in animals and humans have shown that the accumulation and concentration of iodine by the thyroid gland is the result of the selective action of sodium iodine symporter (Na+I+symporter, NIS). Furthermore, it was shown that the accumulation and concentration of (131)I in the parietal cells of the gastric mucosa, the ductal cells of the salivary glands and the alveolar epithelial cells of the mammary glands, is analogous to the biologic action of NIS in the thyroid cells. The gastric mucosa accumulates iodine from the capillaries via the extracellular/extravascular space and finally excretes it into the lumen of the stomach, from where it is passively transferred into the bowel, where it is partially reabsorbed to once again enter its metabolic cycle. On the contrary, as it is now known, the PPI have an entirely different metabolic action, which is unrelated to that of the NIS, although both mechanisms coexist in the parietal cells of the gastric mucosa. Thus, during the application of (131)I for imaging or for the treatment of DTC patients, except for the short period of time immediately after the oral administration, when the radionuclide passes through the stomach, the concentration of (131)I in the gastrointestinal tract is due to its active accumulation and excretion by the gastric mucosa. PPI act only on the hydrochloric acid secretion not affecting the biologic properties of iodine. PMID:17450241

Sfakianakis, George; Sfakianaki, Efrosyni

2007-01-01

46

The effects of pH on proton sugar symport activity of the lactose permease purified from Escherichia coli.  

PubMed

The lactose permease, which catalyzes galactoside-proton symport into Escherichia coli, has been purified and reconstituted in active form into artificial lipid vesicles. The roles of many detergents and phospholipids in solubilization and stabilization of the activity of the permease have been examined with a view to its eventual crystallization. Initial rates of uptake into reconstituted proteoliposomes determined by rapid mixing techniques proved that the activity of the permease can be comparable to that observed in the intact cell, while the best values for uptake rates obtained with conventional techniques were comparable to those reported for vesicles. The activity of the purified protein has been monitored over time periods of hours to weeks. It is shown that, under the best current conditions, the permease retains full activity for 1 to 2 weeks. Although this is still marginal for its crystallization, future improvements can now be assayed by rather stringent criteria. The mechanism of galactoside transport into reconstituted proteoliposome has been investigated by examining the effects of pH on influx into the vesicles. It is shown that the observed effects are entirely consistent with the predictions of a simple model of proton symport. The apparent increase in rate of uptake that is observed in the presence of a pH gradient is not so much due to an acceleration by a component of the protonmotive force as to the relaxation of inhibition by a product (internal protons) of the symport reaction. PMID:3053684

Page, M G; Rosenbusch, J P; Yamato, I

1988-11-01

47

The role of ATP in the control of H+-galactoside symport in the yeast Kluyveromyces marxianus.  

PubMed Central

Transport of methyl beta-D-thiogalactoside and p-nitrophenyl beta-D-galactoside is shown to proceed through the H+-lactose symporter of Kluyveromyces marxianus. Uptake of these compounds is strongly reduced under anaerobic conditions or aerobically in the presence of antimycin. It is shown that antimycin treatment affects p-nitrophenyl beta-D-galactoside uptake in a similar way as it affects the cellular amount of ATP, suggesting regulation of p-nitrophenyl beta-D-galactoside transport by ATP. Also, manipulation of cellular ATP by antimycin treatment followed by glucose incubation, or by aerobic incubation of cells with 2-deoxy-D-glucose, showed a similar dependence of galactoside uptake on the ATP level. Transport of the lipophilic cation tetraphenylphosphonium is affected by ATP variations in a similar way as galactoside influx. It is concluded that ATP regulates H+-galactoside symport by its influence on charge translocation. It is discussed that a membrane ATPase probably plays a central role in the control of the activity of H+-sugar symport. PMID:3036099

Van den Broek, P J; De Bruijne, A W; Van Steveninck, J

1987-01-01

48

Sodium Iodide Symporter for Nuclear Molecular Imaging and Gene Therapy: From Bedside to Bench and Back  

PubMed Central

Molecular imaging, defined as the visual representation, characterization and quantification of biological processes at the cellular and subcellular levels within intact living organisms, can be obtained by various imaging technologies, including nuclear imaging methods. Imaging of normal thyroid tissue and differentiated thyroid cancer, and treatment of thyroid cancer with radioiodine rely on the expression of the sodium iodide symporter (NIS) in these cells. NIS is an intrinsic membrane protein with 13 transmembrane domains and it takes up iodide into the cytosol from the extracellular fluid. By transferring NIS function to various cells via gene transfer, the cells can be visualized with gamma or positron emitting radioisotopes such as Tc-99m, I-123, I-131, I-124 and F-18 tetrafluoroborate, which are accumulated by NIS. They can also be treated with beta- or alpha-emitting radionuclides, such as I-131, Re-186, Re-188 and At-211, which are also accumulated by NIS. This article demonstrates the diagnostic and therapeutic applications of NIS as a radionuclide-based reporter gene for trafficking cells and a therapeutic gene for treating cancers. PMID:22539935

Ahn, Byeong-Cheol

2012-01-01

49

A mechanism for intracellular release of Na(+) by neurotransmitter/sodium symporters.  

PubMed

Neurotransmitter/sodium symporters (NSSs) terminate synaptic signal transmission by Na(+)-dependent reuptake of released neurotransmitters. Key conformational states have been reported for the bacterial homolog LeuT and an inhibitor-bound Drosophila dopamine transporter. However, a coherent mechanism of Na(+)-driven transport has not been described. Here, we present two crystal structures of MhsT, an NSS member from Bacillus halodurans, in occluded inward-facing states with bound Na(+) ions and L-tryptophan, providing insight into the cytoplasmic release of Na(+). The switch from outward- to inward-oriented states is centered on the partial unwinding of transmembrane helix 5, facilitated by a conserved GlyX9Pro motif that opens an intracellular pathway for water to access the Na2 site. We propose a mechanism, based on our structural and functional findings, in which solvation through the TM5 pathway facilitates Na(+) release from Na2 and the transition to an inward-open state. PMID:25282149

Malinauskaite, Lina; Quick, Matthias; Reinhard, Linda; Lyons, Joseph A; Yano, Hideaki; Javitch, Jonathan A; Nissen, Poul

2014-11-01

50

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

51

The Biology of the Sodium Iodide Symporter and its Potential for Targeted Gene Delivery  

PubMed Central

The sodium iodide symporter (NIS) is responsible for thyroidal, salivary, gastric, intestinal and mammary iodide uptake. It was first cloned from the rat in 1996 and shortly thereafter from human and mouse tissue. In the intervening years, we have learned a great deal about the biology of NIS. Detailed knowledge of its genomic structure, transcriptional and post-transcriptional regulation and pharmacological modulation has underpinned the selection of NIS as an exciting approach for targeted gene delivery. A number of in vitro and in vivo studies have demonstrated the potential of using NIS gene therapy as a means of delivering highly conformal radiation doses selectively to tumours. This strategy is particularly attractive because it can be used with both diagnostic (99mTc, 125I, 124I) and therapeutic (131I, 186Re, 188Re, 211At) radioisotopes and it lends itself to incorporation with standard treatment modalities, such as radiotherapy or chemoradiotherapy. In this article, we review the biology of NIS and discuss its development for gene therapy. PMID:20201784

Hingorani, M.; Spitzweg, C.; Vassaux, G.; Newbold, K.; Melcher, A.; Pandha, H.; Vile, R.; Harrington, K.

2013-01-01

52

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

2013-07-01

53

Effects of dose, intervention time, and radionuclide on sodium iodide symporter (NIS)-targeted radionuclide therapy.  

PubMed

The sodium iodide symporter (NIS) mediates iodide uptake into thyrocytes and is the molecular basis of thyroid radioiodine therapy. We previously have shown that NIS gene transfer into the F98 rat gliomas facilitated tumor imaging and increased survival by radioiodine. In this study, we show that: (1) the therapeutic effectiveness of (131)I in prolonging the survival time of rats bearing F98/hNIS gliomas is dose- and treatment-time-dependent; (2) the number of remaining NIS-expressing tumor cells decreased greatly in RG2/hNIS gliomas post (131)I treatment and was inversely related to survival time; (3) 8 mCi each of (125)I/(131)I is as effective as 16 mCi (131)I alone, despite a smaller tumor absorbed dose; (4) (188)ReO(4), a potent beta(-) emitter, is more efficient than (131)I to enhance the survival of rats bearing F98/hNIS gliomas. These studies demonstrate the importance of radiopharmaceutical selection, dose, and timing of treatment to optimize the therapeutic effectiveness of NIS-targeted radionuclide therapy following gene transfer into gliomas. PMID:14712300

Shen, D H Y; Marsee, D K; Schaap, J; Yang, W; Cho, J-Y; Hinkle, G; Nagaraja, H N; Kloos, R T; Barth, R F; Jhiang, S M

2004-01-01

54

Increased Na/H antiporter and Na/3HCO3 symporter activities in chronic hyperfiltration. A model of cell hypertrophy  

PubMed Central

The effect of chronic hyperfiltration, a model of cell hypertrophy, on H/HCO3 transporters was examined in the in vivo microperfused rat proximal tubule. Hyperfiltration was induced by uninephrectomy with subsequent increased dietary protein. After 2 wk the hyperfiltration group had a higher glomerular filtration rate (2.21 +/- 0.13 vs. 1.48 +/- 0.12 ml/min), associated with increased kidney weight (1.71 +/- 0.05 vs. 1.23 +/- 0.04 g). HCO3 absorptive rate measured in tubules perfused with an ultrafiltrate-like solution (25 mM HCO3) was higher in the hyperfiltration group (183 +/- 17 vs. 109 +/- 16 pmol/mm per min). The activities of the apical membrane Na/H antiporter and basolateral membrane Na/3HCO3 symporter were assayed using the measurement of cell pH [(2'7')-bis(carboxyethyl)-(5,6)-carboxyfluorescein] in the doubly microperfused tubule in the absence of contact with native fluids. After 2 wk of hyperfiltration Na/H antiporter activity, assayed as the effect of luminal Na removal on cell pH, was increased 114%. Basolateral membrane Na/3HCO3 symporter activity, assayed as the effect of a decrease in peritubular [HCO3] (25 to 5 mM) or in peritubular [Na] (147 to 25 mM) in the absence of luminal and peritubular chloride, was increased 77 and 113%, respectively, in the hyperfiltration group. Steady-state cell pH, measured with physiologic, ultrafiltrate-like luminal and peritubular perfusates, was significantly higher in the hyperfiltration group (7.27 +/- 0.02 vs. 7.14 +/- 0.03). In similar studies, performed 24 h after uninephrectomy and protein feeding, kidney weight was increased 10%, Na/H antiporter activity 39%, and Na/3HCO3 symporter activity 46%. At this time cell pH was not different between the two groups. The results demonstrate that chronic hyperfiltration is associated with parallel increases in Na/H antiporter and Na/3HCO3 symporter activities. If a decrease in cell pH is the signal that triggers these adaptations, it occurs early, and the adaptations can be maintained in the absence of sustained cell acidification. PMID:1849958

1991-01-01

55

Correlation between 99mTc-pertechnetate uptakes and expressions of human sodium iodide symporter gene in breast tumor tissues  

Microsoft Academic Search

We investigated a correlation between the expression of human sodium iodide symporter (hNIS) mRNA and the uptake of 99mTc-pertechnetate in 25 breast tumors. 99mTc-pertechnetate scintigraphy revealed positive uptake in 4 patients. The normalized mRNA expression of hNIS was higher in tumors with positive uptake on the scintigraphy (n=4, median 0.97, range 0.78–1.27) than that in negative uptake tumors (n=21, median

Dae Hyuk Moon; Sung Jin Lee; Ki Young Park; Kun Ku Park; Se Hyun Ahn; Moon Sun Pai; Hyesook Chang; Hee Kyung Lee; Il-Min Ahn

2001-01-01

56

The Na+/I? symporter (NIS) mediates electroneutral active transport of the environmental pollutant perchlorate  

PubMed Central

The Na+/I? symporter (NIS) is a key plasma membrane protein that mediates active I? uptake in the thyroid, lactating breast, and other tissues with an electrogenic stoichiometry of 2 Na+ per I?. In the thyroid, NIS-mediated I? uptake is the first step in the biosynthesis of the iodine-containing thyroid hormones, which are essential early in life for proper CNS development. In the lactating breast, NIS mediates the translocation of I? to the milk, thus supplying this essential anion to the nursing newborn. Perchlorate (ClO4?) is a well known competitive inhibitor of NIS. Exposure to food and water contaminated with ClO4? is common in the U.S. population, and the public health impact of such exposure is currently being debated. To date, it is still uncertain whether ClO4? is a NIS blocker or a transported substrate of NIS. Here we show in vitro and in vivo that NIS actively transports ClO4?, including ClO4? translocation to the milk. A simple mathematical fluxes model accurately predicts the effect of ClO4? transport on the rate and extent of I? accumulation. Strikingly, the Na+/ ClO4? transport stoichiometry is electroneutral, uncovering that NIS translocates different substrates with different stoichiometries. That NIS actively concentrates ClO4? in maternal milk suggests that exposure of newborns to high levels of ClO4? may pose a greater health risk than previously acknowledged because ClO4? would thus directly inhibit the newborns' thyroidal I? uptake. PMID:18077370

Dohan, Orsolya; Portulano, Carla; Basquin, Cecile; Reyna-Neyra, Andrea; Amzel, L. Mario; Carrasco, Nancy

2007-01-01

57

Transcriptional regulation of human sodium/iodide symporter gene: a role for redox factor-1.  

PubMed

The transcriptional regulation of the human sodium/iodide symporter (NIS) gene in normal and transformed thyroid cells is a crucial issue in attempting to restore iodide uptake and use radioiodine as a therapeutic treatment of thyroid cancer. Previous investigations have shown that the multifunctional protein apurinic apyrimidinic endonuclease/redox factor 1 (APE/Ref-1) plays an important role in regulation of thyroid-specific gene transcription. In this study, we investigated the effects of APE/Ref-1 on human NIS promoter activity. Cotransfection experiments performed in nonthyroid HeLa cells demonstrated that APE/Ref-1 exerts both PAX8-dependent and PAX8-independent effects. In fact, in the absence of PAX8, overexpression of APE/Ref-1 enhanced NIS promoter activity 2-fold. When the expression plasmid of APE/Ref-1 was transfected together with an expression plasmid for PAX8, a strong cooperative effect was detected with an increase of NIS promoter activity 9-fold over control. The PAX8-independent effect of APE/Ref-1 was specific for the NIS promoter, resulting not present for the promoter of the thyroperoxidase (TPO) gene. It was, at least in part, due to the up-regulation of the transcriptional activity of the ubiquitous factor early growth response-1 (Egr-1). In the thyroid tumor cell lines TPC-1 and B-CPAP, APE/Ref-1 was not effective by itself, and it also failed to increase PAX8 stimulation on NIS promoter activity. These data demonstrate a role for APE/Ref-1 protein in the transcriptional regulation of NIS gene expression by itself and in cooperation with PAX8. However, restoring the PAX8-APE/Ref-1 expression in tumor cells may not be sufficient to obtain adequate levels of NIS gene expression. PMID:14630715

Puppin, Cinzia; Arturi, Franco; Ferretti, Elisabetta; Russo, Diego; Sacco, Rosario; Tell, Gianluca; Damante, Giuseppe; Filetti, Sebastiano

2004-03-01

58

Down-regulation of the sodium/iodide symporter explains 131I-induced thyroid stunning.  

PubMed

(131)I radiation therapy of differentiated thyroid cancer may be compromised by thyroid stunning (i.e., a paradoxical inhibition of radioiodine uptake caused by radiation from a pretherapeutic diagnostic examination). The stunning mechanism is yet uncharacterized at the molecular level. We therefore investigated whether the expression of the sodium/iodide symporter (NIS) gene is changed by irradiation using (131)I. Confluent porcine thyroid cells on filter were stimulated with thyroid-stimulating hormone (TSH; 1 milliunit/mL) or insulin-like growth factor-I (IGF-I; 10 ng/mL) and simultaneously exposed to (131)I in the culture medium for 48 h, porcine NIS mRNA was quantified by real-time reverse transcription-PCR using 18S as reference, and transepithelial iodide transport was monitored using (125)I(-) as tracer. TSH increased the NIS expression >100-fold after 48 h and 5- to 20-fold after prolonged stimulation. IGF-I enhanced the NIS transcription at most 15-fold but not until 5 to 7 days. (131)I irradiation (7.5 Gy) decreased both TSH-stimulated and IGF-I-stimulated NIS transcription by 60% to 90% at all investigated time points. TSH and IGF-I stimulated NIS synergistically 15- to 60-fold after 5 days. NIS expression was reduced by (131)I also in costimulated cells, but the transcription level remained higher than in nonirradiated cells stimulated with TSH alone. Changes in NIS mRNA always correlated with altered (125)I(-) transport in cultures with corresponding treatments. It is concluded that down-regulation of NIS is the likely explanation of (131)I-induced thyroid stunning. Enhanced NIS expression by synergistically acting agents (TSH and IGF-I) partly prevents the loss of iodide transport expected from a given absorbed dose, suggesting that thyroid stunning might be pharmacologically treatable. PMID:17671222

Nordén, Madeleine M; Larsson, Fredrik; Tedelind, Sofia; Carlsson, Therese; Lundh, Charlotta; Forssell-Aronsson, Eva; Nilsson, Mikael

2007-08-01

59

Rat sodium iodide symporter allows using lower dose of 131I for cancer therapy.  

PubMed

Efficient gene delivery is a critical obstacle for gene therapy that must be overcome. Until current limits of gene delivery technology are solved, identification of systems with bystander effects is highly desirable. As an anticancer agent, radioactive iodine (131)I has minimal toxicity. The physical characteristics of (131)I decay allow radiation penetration within a local area causing bystander killing of adjacent cells. Accumulation of (131)I mediated by the sodium iodide symporter (NIS) provides a highly effective treatment for well-differentiated thyroid carcinoma. Other types of cancer could also be treated by NIS-mediated concentration of lethal (131)I radiation in tumor cells. Our group and others previously reported that a significant antitumor effect in mice was achieved after adenoviral delivery of rat or human NIS gene following administration of 3 mCi of (131)I. We have also demonstrated 5-6-fold greater uptake of (125)I by rat NIS over human NIS in human cancer cells. Recently, we reported the capability of the rat NIS and (131)I to effectively induce growth arrest of relatively large tumors (approximately 800 mm(3)) in an animal model. In the present work tumor growth inhibition was achieved using adenoviral delivery of the rat NIS gene and 1 mCi of (131)I (one-third of the dose used in earlier reports). We also demonstrated that a higher concentration of (123)I was accumulated in the NIS-expressing tumors than in the thyroid 20 min after radioiodine administration. The highest intratumoral radioiodine concentration was observed along the needle track; however, the rat NIS-(131)I effectively induced growth arrest of tumor xenografts in mice through its radiological bystander effect. Importantly, the rat NIS allowed reducing the injected radioiodine dose by 70% with the same antitumor efficacy in pre-established tumors. These results suggest that the rat NIS gene may be advantageous compared to the human gene in its ability to enhance intratumoral (131)I uptake. PMID:16525480

Mitrofanova, E; Unfer, R; Vahanian, N; Link, C

2006-07-01

60

Expression of the Na+\\/l- symporter (NIS) is markedly decreased or absent in gastric cancer and intestinal metaplastic mucosa of Barrett esophagus  

Microsoft Academic Search

BACKGROUND: The sodium\\/iodide symporter (NIS) is a plasma membrane glycoprotein that mediates iodide (I-) transport in the thyroid, lactating breast, salivary glands, and stomach. Whereas NIS expression and regulation have been extensively investigated in healthy and neoplastic thyroid and breast tissues, little is known about NIS expression and function along the healthy and diseased gastrointestinal tract. METHODS: Thus, we investigated

Áron Altorjay; Orsolya Dohán; Anna Szilágyi; Monika Paroder; Irene L Wapnir; Nancy Carrasco

2007-01-01

61

Structural models of the KtrB, TrkH, and Trk1,2 symporters based on the structure of the KcsA K(+) channel.  

PubMed Central

Three-dimensional computer modeling is used to further investigate the hypothesis forwarded in the accompanying paper of an evolutionary relationship between four related families of K(+) sympoter proteins and the superfamily of K(+) channel proteins. Atomic-scale models are developed for the transmembrane regions of one member from each of the three more distinct symporter families, i.e., a TrkH protein from Escherichia coli, a KtrB protein from Aquifex aeolicus, and a Trk1,2 protein from Schizosaccharomyces pombe. The portions of the four consecutive M1-P-M2 motifs in the symporters that can be aligned with K(+) channel sequences are modeled directly from the recently determined crystal structure of the KcsA K(+) channel from Streptomyces lividans. The remaining portions are developed using our previously accumulated theoretical modeling criteria and principles. Concurrently, the use of these criteria and principles is further supported by the now verified predictions of our previous K(+) channel modeling efforts and the degree to which they are satisfied by the known structure of the KcsA protein. Thus the observed ability of the portions of the symporter models derived from the KcsA crystal structure to also satisfy the theoretical modeling criteria provides additional support for an evolutionary link with K(+) channel proteins. Efforts to further satisfy the criteria and principles suggest that the symporter proteins from fungi and plants (i.e., Trk1,2 and HKT1) form dimeric and/or tetrameric complexes in the membrane. Furthermore, analysis of the atomic-scale models in relation to the sequence conservation within and between the protein families suggests structural details for previously proposed mechanisms for the linked symport of K(+) with Na(+) and H(+). Suggestions are also given for experiments to test these structures and hypotheses. PMID:10423426

Durell, S R; Guy, H R

1999-01-01

62

Amino acid secondary transporters: toward a common transport mechanism.  

PubMed

Solute carriers (SLC) that transport amino acids are key players in health and diseases in humans. Their prokaryotic relatives are often involved in essential physiological processes in microorganisms, e.g. in homeostasis and acidic/osmotic stress response. High-resolution X-ray structures of the sequence-unrelated amino acid transporters unraveled a striking structural similarity between carriers, which were formerly assigned to different families. The highly conserved fold is characterized by two inverted structural repeats of five transmembrane helices each and indicates common mechanistic transport concepts if not an evolutionary link among a large number of amino acid transporters. Therefore, these transporters are classified now into the structural amino acid-polyamine-organocation superfamily (APCS). The APCS includes among others the mammalian SLC6 transporters and the heterodimeric SLC7/SLC3 transporters. However, it has to be noted that the APCS is not limited entirely to amino acid transporters but contains also transporters for, e.g. amino acid derivatives and sugars. For instance, the betaine-choline-carnitine transporter family of bacterial activity-regulated Na(+)- and H(+)-coupled symporters for glycine betaine and choline is also part of this second largest structural superfamily. The APCS fold provides different possibilities to transport the same amino acid. Arginine can be transported by an H(+)-coupled symport or by antiport mechanism in exchange against agmatine for example. The convergence of the mechanistic concept of transport under comparable physiological conditions allows speculating if structurally unexplored amino acid transporters, e.g. the members of the SLC36 and SLC38 family, belong to the APCS, too. In the kidney, which is an organ that depends critically on the regulated amino acid transport, these different SLC transporters have to work together to account for proper function. Here, we will summarize the basic concepts of Na(+)- and H(+)-coupled amino acid symport and amino acid-product antiport in the light of the respective physiological requirements. PMID:23177982

Schweikhard, Eva S; Ziegler, Christine M

2012-01-01

63

Monosaccharide\\/proton symporter AtSTP1 plays a major role in uptake and response of Arabidopsis seeds and seedlings to sugars  

Microsoft Academic Search

Summary The aim of this study was to investigate the in vivo properties and function of the high-affinity monosaccharide\\/proton symporter AtSTP1 of Arabidopsis. We isolated an Atstp1 knock-out mutant and found that this plant grows and develops normally. The AtSTP1 gene is expressed in germinating seeds and seedlings, with AtSTP1 activity found mainly in the seedling root. The rate of

Sarah M. Sherson; Georg Hemmann; Graham Wallace; Susan Forbes; Veronique Germain; Ruth Stadler; Nicole Bechtold; Norbert Sauer; Steven M. Smith

2000-01-01

64

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. PMID:20588260

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

65

B-RafV600E inhibits sodium iodide symporter expression via regulation of DNA methyltransferase 1.  

PubMed

B-RafV600E mutant is found in 40-70% of papillary thyroid carcinoma (PTC) and has an important role in the pathogenesis of PTC. The sodium iodide symporter (NIS) is an integral plasma membrane glycoprotein that mediates active iodide transport into the thyroid follicular cells, and B-RafV600E has been known to be associated with the loss of NIS expression. In this study, we found that B-RafV600E inhibited NIS expression by the upregulation of its promoter methylation, and that specific regions of CpG islands of NIS promoter in B-RafV600E harboring PTC were highly methylated compared with surrounding normal tissue. Although DNA methyltransferase 3a and 3b (DNMT3a,3b) were not increased by B-RafV600E, DNMT1 expression was markedly upregulated in PTC and B-RafV600E expressing thyrocytes. Furthermore, DNMT1 expression was upregulated by B-RafV600E induced NF-?B activation. These results led us to conclude that NIS promoter methylation, which was induced by B-RafV600E, is one of the possible mechanisms involved in NIS downregulation in PTC. PMID:25378232

Choi, Yong Won; Kim, Hyun-Ju; Kim, Young Hwa; Park, So Hyun; Chwae, Yong Jun; Lee, Jeonghun; Soh, Euy Young; Kim, Jang-Hee; Park, Tae Jun

2014-01-01

66

Regulation of iodide uptake and sodium/iodide symporter expression in the mcf-7 human breast cancer cell line.  

PubMed

Sodium/iodide symporter (NIS) expression has recently been described in human breast cancer, with emphasis on its potential exploitation for the treatment of these tumors with radioiodine. In this study, we analyzed the regulation of NIS expression and function in the MCF-7 human breast cancer cell line. Cell exposure to insulin, IGF-I, IGF-II, or prolactin induced significant increases in 125I uptake and the expression of both NIS mRNA and NIS protein. The latter increases were evident after 6 and 12 h of hormonal stimulation, respectively. In immunocytochemistry studies, NIS was detected mainly in the plasma membrane of MCF-7 cells. A low but significant increase in iodide uptake was produced by treatment with activators of the adenylyl cyclase (cAMP) or protein kinase C pathways. Our study demonstrates that: 1) MCF-7 breast cancer cells are capable of active iodide transport that can be stimulated by insulin, IGF-I, IGF-II, or prolactin; 2) both NIS transcript and protein are expressed in these cells, and this expression is also hormonally stimulated; and 3) MCF-7 iodide transport and NIS expression may be influenced by the activation of cAMP or protein kinase C-dependent signaling. These findings increase our understanding of the molecular mechanisms that regulate NIS expression in breast cancer cells, information that is fundamental for future research aimed at the development of targeted radioiodide treatment for this type of cancer. PMID:15623812

Arturi, Franco; Ferretti, Elisabetta; Presta, Ivan; Mattei, Tiziana; Scipioni, Angela; Scarpelli, Daniela; Bruno, Rocco; Lacroix, Ludovic; Tosi, Emanuele; Gulino, Alberto; Russo, Diego; Filetti, Sebastiano

2005-04-01

67

Regulation by human chorionic gonadotropin of sodium/iodide symporter gene expression in the JAr human choriocarcinoma cell line.  

PubMed

Sodium/iodide symporter (NIS) gene and protein expressions have been recently described in human cytotrophoblasts, emphasizing its potential function in the active transport of iodide from the mother to the fetus. In this study we analyzed NIS expression and function in the human JAr placental choriocarcinoma cell line. Using real-time quantitative RT-PCR, we first demonstrated that NIS transcripts are expressed at a high level in JAr cells compared with other cell lines, including thyroid cancer cells. Functional analysis clearly showed that Jar cells are able to concentrate iodide in presence of hCG. Iodide accumulation increased after 2-h exposure to 5 IU/ml hCG, to 6-fold over the basal level after 8 h. This effect was reproduced using forskolin, the cAMP analog (Bu)(2)-cAMP, and phorbol acetate. Moreover, hCG increased both NIS mRNA after 2 h and NIS protein levels after 4 h, reaching a maximum after 8 h in both cases. In conclusion, our data demonstrate that 1) NIS is expressed in JAr cells; 2) iodide transport in JAr cells is regulated by hCG and by cAMP-dependent and -independent mechanisms; 3) the stimulation of iodide uptake is due to an increase in both NIS mRNA and protein levels; and 4) JAr cells may represent an excellent in vitro model suitable to analyze the molecular mechanisms involved in iodide transport from mother to fetus. PMID:12021185

Arturi, Franco; Lacroix, Ludovic; Presta, Ivan; Scarpelli, Daniela; Caillou, Bernard; Schlumberger, Martin; Russo, Diego; Bidart, Jean-Michel; Filetti, Sebastiano

2002-06-01

68

Oncolytic measles virus encoding thyroidal sodium iodide symporter for squamous cell cancer of the head and neck radiovirotherapy.  

PubMed

Oncolytic measles virus (MV) encoding the human thyroidal sodium iodide symporter (MV-NIS) has proved to be safe after intraperitoneal or intravenous administration in patients with ovarian cancer or multiple myeloma, respectively, but it has not yet been administered through intratumoral injection in humans. Squamous cell carcinoma (SCC) of the head and neck (SCCHN) usually is locally invasive and spreads to the cervical lymph nodes, which are suitable for the intratumoral administration of oncolytic viruses. To test whether oncolytic MV is an effective treatment for SCCHN, we used oncolytic MV-NIS to infect SCCHN in vitro and in vivo. The data show that SCCHN cells were infected and killed by MV-NIS in vitro. Permissiveness of the tumor cells to MV infection was not affected by irradiation after viral addition. Monitored noninvasively through radioiodine-based single-photon emission computed tomography/computed tomography, intratumorally virus-delivered NIS has concentrated the radioiodine in the MV-NIS-treated tumors in the FaDu mouse xenograft model of human SCCHN, and the antitumor effect could be boosted significantly (p<0.05) either with concomitant cyclophosphamide therapy or with appropriately timed administration of radioiodine (131)I. MV-NIS could be a promising new anticancer agent that may substantially enhance the outcomes of standard therapy after intratumoral administration in patients with locally advanced SCCHN. PMID:22235810

Li, Hongtao; Peng, Kah-Whye; Russell, Stephen J

2012-03-01

69

Cd2+ versus Zn2+ Uptake by the ZIP8 HCO3?-Dependent Symporter: Kinetics, Electrogenicity and Trafficking  

PubMed Central

The mouse Slc39a8 gene encodes the ZIP8 transporter, which has been shown to be a divalent cation/HCO3? symporter. Using ZIP8 cRNA-injected Xenopus oocyte cultures, we show herein that: [a] ZIP8-mediated cadmium (Cd2+) and zinc (Zn2+) uptake have Vmax values of 1.8 ± 0.08 and 1.0 ± 0.08 pmol/oocyte/hour, and Km values of 0.48 ± 0.08 and 0.26 ± 0.09 ?M, respectively; [b] ZIP8-mediated Cd2+ uptake is most inhibited by Zn2+, second-best inhibited by Cu2+, Pb2+ and Hg2+, and not inhibited by Mn2+ or Fe2+; and [c] electrogenicity studies demonstrate an influx of two HCO3? anions per one Cd2+ (or one Zn2+) 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 Zn2+ homeostasis, but moves predominantly to the cell surface membrane (trafficking) under conditions of Zn2+ depletion. PMID:18037372

Liu, Zhiwei; Li, Hong; Soleimani, Manoocher; Girijashanker, Kuppuswami; Reed, Jodie M.; He, Lei; Dalton, Timothy P.; Nebert, Daniel W.

2007-01-01

70

The Sodium Iodide Symporter (NIS) as an Imaging Reporter for Gene, Viral, and Cell-based Therapies  

PubMed Central

Preclinical and clinical tomographic imaging systems increasingly are being utilized for non-invasive imaging of reporter gene products to reveal the distribution of molecular therapeutics within living subjects. Reporter gene and probe combinations can be employed to monitor vectors for gene, viral, and cell-based therapies. There are several reporter systems available; however, those employing radionuclides for positron emission tomography (PET) or singlephoton emission computed tomography (SPECT) offer the highest sensitivity and the greatest promise for deep tissue imaging in humans. Within the category of radionuclide reporters, the thyroidal sodium iodide symporter (NIS) has emerged as one of the most promising for preclinical and translational research. NIS has been incorporated into a remarkable variety of viral and non-viral vectors in which its functionality is conveniently determined by in vitro iodide uptake assays prior to live animal imaging. This review on the NIS reporter will focus on 1) differences between endogenous NIS and heterologously-expressed NIS, 2) qualitative or comparative use of NIS as an imaging reporter in preclinical and translational gene therapy, oncolytic viral therapy, and cell trafficking research, and 3) use of NIS as an absolute quantitative reporter. PMID:22263922

Penheiter, Alan R; Russell, Stephen J; Carlson, Stephanie K

2012-01-01

71

FSY1, a horizontally transferred gene in the Saccharomyces cerevisiae EC1118 wine yeast strain, encodes a high-affinity fructose/H+ symporter.  

PubMed

Transport of glucose and fructose in the yeast Saccharomyces cerevisiae plays a crucial role in controlling the rate of wine fermentation. In S. cerevisiae, hexoses are transported by facilitated diffusion via hexose carriers (Hxt), which prefer glucose to fructose. However, utilization of fructose by wine yeast is critically important at the end of fermentation. Here, we report the characterization of a fructose transporter recently identified by sequencing the genome of the commercial wine yeast strain EC1118 and found in many other wine yeasts. This transporter is designated Fsy1p because of its homology with the Saccharomyces pastorianus fructose/H(+) symporter Fsy1p. A strain obtained by transformation of the V5 hxt1-7? mutant with FSY1 grew well on fructose, but to a much lesser extent on glucose as the sole carbon source. Sugar uptake and symport experiments showed that FSY1 encodes a proton-coupled symporter with high affinity for fructose (K(m) 0.24±0.04mM). Using real-time RT-PCR, we also investigated the expression pattern of FSY1 in EC1118 growing on various carbon sources. FSY1 was repressed by high concentrations of glucose or fructose and was highly expressed on ethanol as the sole carbon source. The characteristics of this transporter indicate that its acquisition could confer a significant advantage to S. cerevisiae during the wine fermentation process. This transporter is a good example of acquisition of a new function in yeast by horizontal gene transfer. PMID:20705659

Galeote, Virginie; Novo, Maïté; Salema-Oom, Madalena; Brion, Christian; Valério, Elisabete; Gonçalves, Paula; Dequin, Sylvie

2010-12-01

72

Conserved Tyrosine in the First Transmembrane Segment of Solute:Sodium Symporters Is Involved in Na+-coupled Substrate Co-transport*  

PubMed Central

Solute:sodium symporters (SSSs) transport vital molecules across the plasma membrane of all living organisms. vSGLT, the Na+/galactose transporter of Vibrio parahemeolyticus, is the only SSS for which high resolution structural information is available, revealing a LeuT-like fold and a Na+-binding site analogous to the Na2 site of LeuT. Whereas the core transmembrane segments (TMs) of SSSs share high structural similarity with other transporters of LeuT-like fold, TM1 does not correspond to any TM in those structural homologs and was only resolved for the backbone atoms in the initial vSGLT structure (Protein Data Bank code 3DH4). To assess the role of TM1 in Na+-coupled substrate symport by the SSSs, here we have studied the role of a conserved residue in TM1 by computational modeling in conjunction with radiotracer transport and binding studies. Based on our sequence alignment and much topological data for homologous PutP, the Na+/proline transporter, we have simulated a series of vSGLT models with shifted TM1 residue assignments. We show that in two converged vSGLT models that retained the original TM1 backbone conformation, a conserved residue, Tyr-19, is associated with the Na+ binding interaction network. In silico and in vitro mutagenesis of homologous Tyr-14 in PutP revealed the involvement of this conserved residue in Na+-dependent substrate binding and transport. Thus, our combined computational and experimental data provide the first clues about the importance of a conserved residue in TM1, a unique TM in the proteins with LeuT-like fold, in the Na+-coupled symport mechanism of SSSs. PMID:21705334

Mazier, Sonia; Quick, Matthias; Shi, Lei

2011-01-01

73

Wild-type p53 enhances the cytotoxic effect of radionuclide gene therapy using sodium iodide symporter in a murine anaplastic thyroid cancer model  

Microsoft Academic Search

Purpose  To evaluate the role of p53 in radionuclide gene therapy, we investigated the cytotoxic effect of 131I and 188Re following cotransfection of the sodium iodide symporter (NIS) and wild-type p53 (wt-p53) genes into cancer cells.\\u000a \\u000a \\u000a \\u000a Methods  The NIS gene was transfected to human anaplastic thyroid carcinoma cells (ARO) expressing mutant p53 (mt-p53) using liposomes.\\u000a The uptakes of 125I and 188Re were

Yong Jin Lee; June-Key Chung; Joo Hyun Kang; Jae Min Jeong; Dong Soo Lee; Myung Chul Lee

2010-01-01

74

Optimization of Multimodal Imaging of Mesenchymal Stem Cells Using the Human Sodium Iodide Symporter for PET and Cerenkov Luminescence Imaging  

PubMed Central

Purpose The use of stably integrated reporter gene imaging provides a manner to monitor the in vivo fate of engrafted cells over time in a non-invasive manner. Here, we optimized multimodal imaging (small-animal PET, Cerenkov luminescence imaging (CLI) and bioluminescence imaging (BLI)) of mesenchymal stem cells (MSCs), by means of the human sodium iodide symporter (hNIS) and firefly luciferase (Fluc) as reporters. Methods First, two multicistronic lentiviral vectors (LV) were generated for multimodal imaging: BLI, 124I PET/SPECT and CLI. Expression of the imaging reporter genes was validated in vitro using 99mTcO4? radioligand uptake experiments and BLI. Uptake kinetics, specificity and tracer elution were determined as well as the effect of the transduction process on the cell's differentiation capacity. MSCs expressing the LV were injected intravenously or subcutaneously and imaged using small-animal PET, CLI and BLI. Results The expression of both imaging reporter genes was functional and specific. An elution of 99mTcO4? from the cells was observed, with 31% retention after 3 h. After labeling cells with 124I in vitro, a significantly higher CLI signal was noted in hNIS expressing murine MSCs. Furthermore, it was possible to visualize cells injected intravenously using BLI or subcutaneously in mice, using 124I small-animal PET, CLI and BLI. Conclusions This study identifies hNIS as a suitable reporter gene for molecular imaging with PET and CLI, as confirmed with BLI through the expression of Fluc. It supports the potential for a wider application of hNIS reporter gene imaging and future clinical applications. PMID:24747914

Wolfs, Esther; Holvoet, Bryan; Gijsbers, Rik; Casteels, Cindy; Roberts, Scott J.; Struys, Tom; Maris, Michael; Ibrahimi, Abdelilah; Debyser, Zeger; Van Laere, Koen; Verfaillie, Catherine M.; Deroose, Christophe M.

2014-01-01

75

Evidence for Transcriptional and Posttranscriptional Alterations of the Sodium/Iodide Symporter Expression in Hypofunctioning Benign and Malignant Thyroid Tumors  

PubMed Central

The uptake of iodide by epithelial thyroid cells requires the expression of a specific transporter, the Na+/I? symporter, NIS. Benign and malignant thyroid tumors of epithelial origin show a decrease up to a loss of iodide uptake activity. Previous studies of the human NIS (hNIS) gene expression in these tumors, based on the amplification of transcripts and/or immunohistochemical detection of the protein, have yielded divergent data; hNIS expression was found either increased or decreased. To get a new and integrated view of the alterations of hNIS expression in hypofunctioning thyroid tumors, we performed investigations of hNIS transcript and hNIS protein levels on the same tumors and paired normal tissue samples. HNIS, identified as a 75- to 80-kd species, was present in all normal tissue samples from euthyroid patients, but was undetectable, even at high membrane protein input, in all benign and malignant hypofunctioning thyroid tumors. By contrast, ?50% of tumors contained hNIS transcripts. This dissociation between transcript and protein levels was not found for the transcript and protein encoded by the PDS gene assayed in the same tumors. The hNIS transcript-positive tumors contained small amounts of low-molecular mass hNIS-immunoreactive species identified as nonglycosylated hNIS. Tumors containing the nonmature form of hNIS exhibited a predominant intracellular immunolabeling. In conclusion, our data show that benign and malignant hypofunctioning thyroid tumors either no longer express hNIS protein or express only a very low amount of nonglycosylated hNIS and indicate that the impairment of hNIS gene expression might result from alterations at both transcriptional and posttranscriptional levels. PMID:15215159

Trouttet-Masson, Severine; Selmi-Ruby, Samia; Bernier-Valentin, Francoise; Porra, Valerie; Berger-Dutrieux, Nicole; Decaussin, Myriam; Peix, Jean-Louis; Perrin, Agnes; Bournaud, Claire; Orgiazzi, Jacques; Borson-Chazot, Francoise; Franc, Brigitte; Rousset, Bernard

2004-01-01

76

Cellular Bioenergetics is an Important Determinant of the Molecular Imaging Signal Derived from Luciferase and the Sodium-Iodide Symporter  

PubMed Central

Rationale Molecular imaging is useful for longitudinal assessment of engraftment. However, it is not known which factors, other than cell number can influence the molecular imaging signal obtained from reporter genes. Objective The effects of cell dissociation/suspension on cellular bioenergetics and the signal obtained by firefly luciferase(fluc) and human Na-I symporter(hNIS) labeling of cardiosphere-derived cells (CDCs) was investigated. Methods and Results 18FDG uptake, ATP levels, 99mTc-pertechnetate uptake and bioluminescence were measured in vitro, in adherent and suspended CDCs. In vivo dual isotope SPECT-CT imaging or bioluminescence imaging (BLI) were performed 1hr and 24hrs following CDC transplantation. SPECT quantification was performed using a phantom for signal calibration. Cell loss between 1hr & 24hrs post-transplantation was quantified by qPCR and ex vivo luciferase assay. Cell dissociation followed by suspension for 1hr resulted in decreased glucose uptake, cellular ATP, 99mTc uptake and BLI signal by 82%, 43%, 42%, and 44% respectively, when compared to adherent cells, in vitro. In vivo 99mTc uptake was significantly lower at 1hr, when compared to 24hrs following cell transplantation in the non-infarct (p<0.001, n=3) and infarct (p<0.001, n =4) model, despite significant cell loss during this period. The in vivo BLI signal was significantly higher at 1hr than at 24hrs (p<0.01), with the BLI signal being higher when CDCs were suspended in glucose-containing medium compared to saline(PBS). Conclusion Adhesion is an important determinant of cellular bioenergetics, 99mTc-pertechnetate uptake and BLI signal. BLI and NIS imaging may be useful for in vivo optimization of bioenergetics in transplanted cells. PMID:23255420

Chang, Connie; Chan, Angel; Lin, Xiaoping; Higuchi, Takahiro; Terrovitis, John; Afzal, Junaid M.; Rittenbach, Andrew; Sun, Dongdong; Vakrou, Styliani; Woldemichael, Kirubel; O'Rourke, Brian; Wahl, Richard; Pomper, Martin; Tsui, Benjamin; Abraham, M. Roselle

2013-01-01

77

Treatment of medulloblastoma using an oncolytic measles virus encoding the thyroidal sodium iodide symporter shows enhanced efficacy with radioiodine  

PubMed Central

Background Medulloblastoma is the most common malignant brain tumor of childhood. Although the clinical outcome for medulloblastoma patients has improved significantly, children afflicted with the disease frequently suffer from debilitating side effects related to the aggressive nature of currently available therapy. Alternative means for treating medulloblastoma are desperately needed. We have previously shown that oncolytic measles virus (MV) can selectively target and destroy medulloblastoma tumor cells in localized and disseminated models of the disease. MV-NIS, an oncolytic measles virus that encodes the human thyroidal sodium iodide symporter (NIS), has the potential to deliver targeted radiotherapy to the tumor site and promote a localized bystander effect above and beyond that achieved by MV alone. Methods We evaluated the efficacy of MV-NIS against medulloblastoma cells in vitro and examined their ability to incorporate radioiodine at various timepoints, finding peak uptake at 48 hours post infection. The effects of MV-NIS were also evaluated in mouse xenograft models of localized and disseminated medulloblastoma. Athymic nude mice were injected with D283med-Luc medulloblastoma cells in the caudate putamen (localized disease) or right lateral ventricle (disseminated disease) and subsequently treated with MV-NIS. Subsets of these mice were given a dose of 131I at 24, 48 or 72 hours later. Results MV-NIS treatment, both by itself and in combination with 131I, elicited tumor stabilization and regression in the treated mice and significantly extended their survival times. Mice given 131I were found to concentrate radioiodine at the site of their tumor implantations. In addition, mice with localized tumors that were given 131I either 24 or 48 hours after MV-NIS treatment exhibited a significant survival advantage over mice given MV-NIS alone. Conclusions These data suggest MV-NIS plus radioiodine may be a potentially useful therapy for the treatment of medulloblastoma. PMID:23134812

2012-01-01

78

Imaging Characteristics, Tissue Distribution, and Spread of a Novel Oncolytic Vaccinia Virus Carrying the Human Sodium Iodide Symporter  

PubMed Central

Introduction Oncolytic viruses show promise for treating cancer. However, to assess therapy and potential toxicity, a noninvasive imaging modality is needed. This study aims to determine the in vivo biodistribution, and imaging and timing characteristics of a vaccinia virus, GLV-1h153, encoding the human sodium iodide symporter (hNIS. Methods GLV-1h153 was modified from GLV-1h68 to encode the hNIS gene. Timing of cellular uptake of radioiodide 131I in human pancreatic carcinoma cells PANC-1 was assessed using radiouptake assays. Viral biodistribution was determined in nude mice bearing PANC-1 xenografts, and infection in tumors confirmed histologically and optically via Green Fluorescent Protein (GFP) and bioluminescence. Timing characteristics of enhanced radiouptake in xenografts were assessed via 124I-positron emission tomography (PET). Detection of systemic administration of virus was investigated with both 124I-PET and 99m-technecium gamma-scintigraphy. Results GLV-1h153 successfully facilitated time-dependent intracellular uptake of 131I in PANC-1 cells with a maximum uptake at 24 hours postinfection (P<0.05). In vivo, biodistribution profiles revealed persistence of virus in tumors 5 weeks postinjection at 109 plaque-forming unit (PFU)/gm tissue, with the virus mainly cleared from all other major organs. Tumor infection by GLV-1h153 was confirmed via optical imaging and histology. GLV-1h153 facilitated imaging virus replication in tumors via PET even at 8 hours post radiotracer injection, with a mean %ID/gm of 3.82±0.46 (P<0.05) 2 days after intratumoral administration of virus, confirmed via tissue radiouptake assays. One week post systemic administration, GLV-1h153-infected tumors were detected via 124I-PET and 99m-technecium-scintigraphy. Conclusion GLV-1h153 is a promising oncolytic agent against pancreatic cancer with a promising biosafety profile. GLV-1h153 facilitated time-dependent hNIS-specific radiouptake in pancreatic cancer cells, facilitating detection by PET with both intratumoral and systemic administration. Therefore, GLV-1h153 is a promising candidate for the noninvasive imaging of virotherapy and warrants further study into longterm monitoring of virotherapy and potential radiocombination therapies with this treatment and imaging modality. PMID:22912675

Haddad, Dana; Chen, Chun-Hao; Carlin, Sean; Silberhumer, Gerd; Chen, Nanhai G.; Zhang, Qian; Longo, Valerie; Carpenter, Susanne G.; Mittra, Arjun; Carson, Joshua; Au, Joyce; Gonen, Mithat; Zanzonico, Pat B.; Szalay, Aladar A.; Fong, Yuman

2012-01-01

79

Sequence analysis of the upstream region of dhlB , the gene encoding haloalkanoic acid dehalogenase of Xanthobacter autotrophicus GJ10  

Microsoft Academic Search

The DNA sequence upstream of thedhlB gene encoding the haloalkanoic acid dehalogenase ofXanthobacter autotrophicus GJ10 was determined and contained an open reading frame, designateddhlC, which encoded a protein with a significant similarity with the family of Na+-dependent symport proteins. ThedhlC gene was subcloned under control of a T7 promoter, and found to encode a polypeptide of 45 kDa on SDS-PAGE.

Jan Ploeg; Dick B. Janssen

1995-01-01

80

The H+/Cl- Symporter in Root-Hair Cells of Sinapis alba (An Electrophysiological Study Using Ion-Selective Microelectrodes).  

PubMed Central

In root-hair cells of Sinapis alba, cytosolic pH, cytosolic [Cl-], membrane potential, and membrane resistance have been measured to investigate proton-driven Cl- transport across the plasma membrane. Rapid lowering of the external pH transiently increased cytosolic [Cl-] and acidified the cytoplasm. To an abrupt increase in external [Cl-] the cells reacted with a rapid initial depolarization and a subsequent slower hyperpolarization, which was accompanied by an increase in cytosolic [Cl-] and [H+]. These results are indicative of an nH+/Cl- symport with n > 1. Simultaneous recording of the membrane potential, the proton motive force, cytosolic pH, and cytosolic [Cl-] reveals that kinetically this Cl- transport depends on the pH gradient across the plasma membrane rather than on the membrane potential. PMID:12232395

Felle, H. H.

1994-01-01

81

Effective carbon partitioning driven by exotic phloem-specific regulatory elements fused to the Arabidopsis thaliana AtSUC2 sucrose-proton symporter gene  

PubMed Central

Background AtSUC2 (At1g22710) from Arabidopsis thaliana encodes a phloem-localized sucrose/proton symporter required for efficient photoassimilate transport from source tissues to sink tissues. AtSUC2 plays a key role in coordinating the demands of sink tissues with the output capacity of source leaves, and in maintaining phloem hydrostatic pressure during changes in plant-water balance. Expression and activity are regulated, both positively and negatively, by developmental (sink to source transition) and environmental cues, including light, diurnal changes, photoassimilate levels, turgor pressure, drought and osmotic stress, and hormones. Results To assess the importance of this regulation to whole-plant growth and carbon partitioning, AtSUC2 cDNA was expressed from two exotic, phloem-specific promoters in a mutant background debilitated for AtSUC2 function. The first was a promoter element from Commelina Yellow Mottle Virus (CoYMV), and the second was the rolC promoter from Agrobacterium rhizogenes. CoYMVp::AtSUC2 cDNA restored growth and carbon partitioning to near wild-type levels, whereas plants harboring rolCp::AtSUC2 cDNA showed only partial complementation. Conclusion Expressing AtSUC2 cDNA from exotic, phloem-specific promoters argues that strong, phloem-localized expression is sufficient for efficient transport. Expressing AtSUC2 from promoters that foster efficient phloem transport but are subject to regulatory cascades different from the endogenous sucrose/proton symporter genes has implications for biotechnology. PMID:19154603

Srivastava, Avinash C; Ganesan, Savita; Ismail, Ihab O; Ayre, Brian G

2009-01-01

82

AMP-activated protein kinase activation leads to lysome-mediated NA(+)/I(-)-symporter protein degradation in rat thyroid cells.  

PubMed

Iodide uptake by thyroid cells is mediated by a transmembrane glycoprotein known as the Na+/I--symporter (NIS). NIS-mediated iodide uptake plays important physiological role in thyroid gland function, as well as in diagnostic and treatment of Graves' disease and thyroid cancer. Although different studies investigated the transcriptional mechanisms of NIS expression, there is no report on the NIS post-translational regulation related to NIS protein degradation in thyroid cells. Recently, our group showed that AMP-activated protein kinase (AMPK) plays a pivotal role in the rat thyroid gland, downregulating iodide uptake, NIS protein, and mRNA content. Since several studies demonstrated that AMPK regulates post-transcriptional mechanisms, such as autophagy-mediated processes in different tissues, we hypothesized that AMPK activation could also regulate NIS protein degradation through the lysosome pathway in thyroid cells. Rat follicular thyroid PCCL3 cells cultivated in Ham's F12 supplemented with 5% calf serum and hormones were exposed to the AMPK pharmacological activator 5-aminoimidazole-4 carboxamide ribonucleoside (AICAR), in the presence or absence of Bafilomycin A1 or MG132 for 24?h. Treatment of PCCL3 cells with Bafilomycin A1 fully prevented the decrease of iodide uptake and NIS protein content mediated by AMPK activation. In contrast, the treatment with MG132 was unable to prevent the effects of AMPK activation on NIS. Our results show that AMPK activation significantly induces NIS protein degradation through a lysosome-mediated mechanism. PMID:24691731

Cazarin, J M; Andrade, B M; Carvalho, D P

2014-05-01

83

Arabidopsis POLYOL TRANSPORTER5, a new member of the monosaccharide transporter-like superfamily, mediates H+-Symport of numerous substrates, including myo-inositol, glycerol, and ribose.  

PubMed

Six genes of the Arabidopsis thaliana monosaccharide transporter-like (MST-like) superfamily share significant homology with polyol transporter genes previously identified in plants translocating polyols (mannitol or sorbitol) in their phloem (celery [Apium graveolens], common plantain [Plantago major], or sour cherry [Prunus cerasus]). The physiological role and the functional properties of this group of proteins were unclear in Arabidopsis, which translocates sucrose and small amounts of raffinose rather than polyols. Here, we describe POLYOL TRANSPORTER5 (AtPLT5), the first member of this subgroup of Arabidopsis MST-like transporters. Transient expression of an AtPLT5-green fluorescent protein fusion in plant cells and functional analyses of the AtPLT5 protein in yeast and Xenopus oocytes demonstrate that AtPLT5 is located in the plasma membrane and characterize this protein as a broad-spectrum H+-symporter for linear polyols, such as sorbitol, xylitol, erythritol, or glycerol. Unexpectedly, however, AtPLT5 catalyzes also the transport of the cyclic polyol myo-inositol and of different hexoses and pentoses, including ribose, a sugar that is not transported by any of the previously characterized plant sugar transporters. RT-PCR analyses and AtPLT5 promoter-reporter gene plants revealed that AtPLT5 is most strongly expressed in Arabidopsis roots, but also in the vascular tissue of leaves and in specific floral organs. The potential physiological role of AtPLT5 is discussed. PMID:15598803

Klepek, Yvonne-Simone; Geiger, Dietmar; Stadler, Ruth; Klebl, Franz; Landouar-Arsivaud, Lucie; Lemoine, Rémi; Hedrich, Rainer; Sauer, Norbert

2005-01-01

84

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 PMID:18682709

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

85

Arabidopsis POLYOL TRANSPORTER5, a New Member of the Monosaccharide Transporter-Like Superfamily, Mediates H+-Symport of Numerous Substrates, Including myo-Inositol, Glycerol, and Ribose  

PubMed Central

Six genes of the Arabidopsis thaliana monosaccharide transporter-like (MST-like) superfamily share significant homology with polyol transporter genes previously identified in plants translocating polyols (mannitol or sorbitol) in their phloem (celery [Apium graveolens], common plantain [Plantago major], or sour cherry [Prunus cerasus]). The physiological role and the functional properties of this group of proteins were unclear in Arabidopsis, which translocates sucrose and small amounts of raffinose rather than polyols. Here, we describe POLYOL TRANSPORTER5 (AtPLT5), the first member of this subgroup of Arabidopsis MST-like transporters. Transient expression of an AtPLT5–green fluorescent protein fusion in plant cells and functional analyses of the AtPLT5 protein in yeast and Xenopus oocytes demonstrate that AtPLT5 is located in the plasma membrane and characterize this protein as a broad-spectrum H+-symporter for linear polyols, such as sorbitol, xylitol, erythritol, or glycerol. Unexpectedly, however, AtPLT5 catalyzes also the transport of the cyclic polyol myo-inositol and of different hexoses and pentoses, including ribose, a sugar that is not transported by any of the previously characterized plant sugar transporters. RT-PCR analyses and AtPLT5 promoter-reporter gene plants revealed that AtPLT5 is most strongly expressed in Arabidopsis roots, but also in the vascular tissue of leaves and in specific floral organs. The potential physiological role of AtPLT5 is discussed. PMID:15598803

Klepek, Yvonne-Simone; Geiger, Dietmar; Stadler, Ruth; Klebl, Franz; Landouar-Arsivaud, Lucie; Lemoine, Remi; Hedrich, Rainer; Sauer, Norbert

2005-01-01

86

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. PMID:21047428

2010-01-01

87

Transport and catabolism of the sialic acids N-glycolylneuraminic acid and 3-keto-3-deoxy-D-glycero-D-galactonononic acid by Escherichia coli K-12.  

PubMed

Escherichia coli can transport and catabolize the common sialic acid, N-acetylneuraminic acid (Neu5Ac), as a sole source of carbon and nitrogen, which is an important mucus-derived carbon source in the mammalian gut. Herein we demonstrate that E. coli can also grow efficiently on the related sialic acids, N-glycolylneuraminic acid (Neu5Gc) and 3-keto-3-deoxy-D-glycero-D-galactonononic acid (KDN), which are transported via the sialic acid transporter NanT and catabolized using the sialic acid aldolase NanA. Catabolism of Neu5Gc uses the same pathway as Neu5Ac, likely producing glycolate instead and acetate during its breakdown and catabolism of KDN requires NanA activity, while other components of the Neu5Ac catabolism pathway are non-essential. We also demonstrate that these two sialic acids can support growth of an E. coli ?nanT strain expressing sialic acid transporters from two bacterial pathogens, namely the tripartite ATP-independent periplasmic transporter SiaPQM from Haemophilus influenzae and the sodium solute symport transporter STM1128 from Salmonella enterica ssp. Typhimurium, suggesting that the ability to use Neu5Gc and KDN in addition to Neu5Ac is present in a number of human pathogens. PMID:23848303

Hopkins, Adam P; Hawkhead, Judith A; Thomas, Gavin H

2013-10-01

88

Normalisation to Blood Activity Is Required for the Accurate Quantification of Na/I Symporter Ectopic Expression by SPECT/CT in Individual Subjects  

PubMed Central

The utilisation of the Na/I symporter (NIS) and associated radiotracers as a reporter system for imaging gene expression is now reaching the clinical setting in cancer gene therapy applications. However, a formal assessment of the methodology in terms of normalisation of the data still remains to be performed, particularly in the context of the assessment of activities in individual subjects in longitudinal studies. In this context, we administered to mice a recombinant, replication-incompetent adenovirus encoding rat NIS, or a human colorectal carcinoma cell line (HT29) encoding mouse NIS. We used 99mTc pertechnetate as a radiotracer for SPECT/CT imaging to determine the pattern of ectopic NIS expression in longitudinal kinetic studies. Some animals of the cohort were culled and NIS expression was measured by quantitative RT-PCR and immunohistochemistry. The radioactive content of some liver biopsies was also measured ex vivo. Our results show that in longitudinal studies involving datasets taken from individual mice, the presentation of non-normalised data (activity expressed as %ID/g or %ID/cc) leads to ‘noisy’, and sometimes incoherent, results. This variability is due to the fact that the blood pertechnetate concentration can vary up to three-fold from day to day. Normalisation of these data with blood activities corrects for these inconsistencies. We advocate that, blood pertechnetate activity should be determined and used to normalise the activity measured in the organ/region of interest that expresses NIS ectopically. Considering that NIS imaging has already reached the clinical setting in the context of cancer gene therapy, this normalisation may be essential in order to obtain accurate and predictive information in future longitudinal clinical studies in biotherapy. PMID:22470517

Richard-Fiardo, Peggy; Franken, Philippe R.; Lamit, Audrey; Marsault, Robert; Guglielmi, Julien; Cambien, Beatrice; Graslin, Fanny; Lindenthal, Sabine; Darcourt, Jacques; Pourcher, Thierry; Vassaux, Georges

2012-01-01

89

The putative electrogenic nitrate-proton symport of the yeast Candida utilis. Comparison with the systems absorbing glucose or lactate.  

PubMed Central

Strain N.C.Y.C. 193 of Candida utilis was grown aerobically at 30 degrees C with nitrate as limiting nutrient in a chemostat. The washed yeast cells depleted of ATP absorbed up to 5 nmol of nitrate/mg dry wt. of yeast. At pH 4-6, extra protons and nitrate entered the yeast cells together, in a ratio of about 2:1. Charge balance was maintained by an outflow of about 1 equiv. of K+. Nitrate stimulated the uptake of about 1 proton equivalent during glycolysis or aerobic energy metabolism. Studies with 3,3'-dipropylthiadicarbocyanine indicated that the proton-linked absorption of nitrate, amino acids or glucose depolarized the yeast cells. Proton uptake along with lactate led neither to net expulsion of K+ nor to membrane depolarization. PMID:2998345

Eddy, A A; Hopkins, P G

1985-01-01

90

Feasibility of lentiviral?mediated sodium iodide symporter gene delivery for the efficient monitoring of bone marrow?derived mesenchymal stem cell transplantation and survival.  

PubMed

The aim of the present study was to explore the feasibility of lentiviral?mediated sodium iodide symporter (NIS) gene delivery for monitoring bone marrow?derived mesenchymal stem cell (BMSC) transplantation into the infarcted myocardium. For this purpose, we constructed a lentiviral vector (Lv?EF1??NIS?IRES?EGFP) expressing NIS and enhanced green fluorescent protein (EGFP), and introduced it into BMSCs at different multiplicities of infection (MOI). The expression of EGFP was observed under a fluorescence microscope. Iodine uptake and the inhibition of iodine uptake by sodium perchlorate (NaClO4) in the Lv?EF1??NIS?IRES?EGFP?treated BMSCs were dynamically monitored in vitro. The Lv?EF1??NIS?IRES?EGFP?treated BMSCs were transplanted into the infarcted myocardium of Sprague?Dawley rats, and 99mTc99g (Tc, technetium; 99m indicates that technetium is at its excited stage; 99g indicates the atomic weight of technetium) micro?single-photon emission computed tomography (SPECT)/computed tomography (CT) imaging was performed in vivo 1 week following transplantation. The isolated BMSCs successfully differentiated into adipocytes and osteoblasts. The BMSCs were positive for the cell surface markers, CD105, CD29 and CD90, and negative for CD14, CD34 and CD45. Lv?EF1??NIS?IRES?EGFP was efficiently transfected into the BMSCs. RT?qPCR and western blot analysis confirmed that the BMSCs expressed high protein and mRNA levels of NIS by day 7 following infection, and NIS expression remained at a consistent level from day 14 to 21. In the Lv?EF1??NIS?IRES?EGFP?treated BMSCs, the accumulation of iodine-125 (125I) was observed in vitro and was successfully monitored by 99mTc99g micro?SPECT/CT imaging at 1 week following transplantation. These results suggest that lentiviral vectors are powerful vehicles for studying gene delivery in BMSCs. It is feasible to use lentiviral vectors to deliver an NIS gene for the non?invasive monitoring of BMSC transplantation and survival in the infarcted myocardium in vivo. PMID:25319483

Shi, Shuo; Zhang, Min; Guo, Rui; Miao, Ying; Zhang, Miao; Hu, Jiajia; Xi, Yun; Li, Biao

2014-12-01

91

Moderate doses of iodide in vivo inhibit cell proliferation and the expression of thyroperoxidase and Na+/I- symporter mRNAs in dog thyroid.  

PubMed

The function and the growth of adult thyroid gland is controlled by the opposite actions of thyrotropin (TSH) and iodide, the main substrate of the gland. Iodide deprivation leads to stimulation of the thyroid, improving the efficiency of iodide transport for hormone biosynthesis. We have investigated cell proliferation and thyroid specific gene expression 24 and 48 h after administering KI to dogs previously treated with goitrogens and perchlorate. In the hypothyroid dogs T3 and T4 serum levels decreased from 53 +/- 4 to < 30 ng/dl and from 1.6 +/- 0.6 to < 1 microg/dl respectively; TSH concentration increased from 0.16 +/- 0.02 to 2.7 +/- 0.4 ng/ml. After a 24 h moderate KI treatment (300 microg KI/dog of +/- 10 kg) serum T3 concentrations rose higher than the initial normal values, while T4 concentrations increased to reach values equivalent to the normal level. The high TSH concentration did not change significantly. The hyperplasia of the chronically stimulated thyroid resulting from goitrogens/NaClO4 treatment was not modified by this short term treatment with KI. In contrast, KI decreased the weight of the total gland and the level of cell proliferation, as determined by the fraction of cells incorporating BrdU. The effect of acute administration of KI on the expression of four major thyroid genes, the TSH receptor (TSHr), thyroglobulin (Tg), thyroperoxidase (TPO), and Na+/I- symporter (NIS) was analyzed by Northern blot. Tg, TPO and NIS mRNA expressions were up-regulated by chronic stimulation. The expression of the mRNAs of TSHr and Tg did not significantly differ between hyperstimulated and KI-treated dogs while TPO and NIS mRNA expression decreased after a 48 h KI treatment. TPO and NIS are therefore the only of these four genes whose expression is acutely modulated by iodide in vivo. Under TSH stimulation low doses of iodide resulted in: (1) decreased cell proliferation, (2) reestablished synthesis and secretion of thyroid hormones, (3) diminished TPO and NIS mRNA expression. Notably low doses of iodide under the same conditions had no effect on Tg and TSHr mRNA expression. PMID:9296378

Uyttersprot, N; Pelgrims, N; Carrasco, N; Gervy, C; Maenhaut, C; Dumont, J E; Miot, F

1997-08-01

92

Potential usefulness of baculovirus-mediated sodium-iodide symporter reporter gene as non-invasively gene therapy monitoring in liver cancer cells: an in vitro evaluation.  

PubMed

Primary liver cancer has one of the highest mortality rates of all cancers, and the main current treatments have a poor prognosis. This study aims to examine the efficiency of baculovirus vectors for transducing target gene into liver cancer cells and to evaluate the feasibility of using baculovirus vectors to deliver the sodium-iodide symporter (NIS) gene as a reporter gene through co-vector administration approach to monitor the expression of the target therapeutic gene in liver cancer gene therapy. We constructed (green fluorescent protein) GFP- and NIS-expressing baculovirus vectors (Bac-GFP and Bac-NIS), and measured the baculovirus transduction efficiency in HepG2 cells and other tumor cells (A549, SW1116 and 8505C), and it showed that the transduction efficiency and target gene expression level rose with increasing viral multiplicity of infection (MOI) in HepG2 cells, and HepG2 cells had a significantly higher transduction efficiency (60.8% at MOI = 200) than other tumor cells. Moreover, the baculovirus transduction was not cytotoxic to HepG2 cells at a higher MOI (MOI 5 400). We also performed dynamic iodide uptake trials, and found that Bac-NIS-transduced HepG2 cells exhibited efficient iodide uptake which could be inhibited by sodium perchlorate (NaClO?). And we measured the correlation of fluorescent intensities and 125I uptake amount in HepG2 cells after co-vector administration with Bac-NIS and Bac-GFP at different MOIs, and found a high correlation coefficient (r(2) = 0.8447), which provides a good basis for successfully evaluating the feasibility of baculovirus-mediated NIS reporter gene monitoring target gene expression in liver cancer therapy. Therefore, this study indicates that baculovirus vector is a potential vehicle for delivering therapeutic genes in studying liver cancer cells. And it is feasible to use a baculovirus vector to deliver NIS gene as a reporter gene to monitor the expression of target genes. It therefore provides an effective approach and a good basis for future baculovirus-mediated therapeutic gene delivering or therapeutic gene expression monitoring in liver cancer cells studies. PMID:23919394

Pan, Yu; Wu, Haifei; Liu, Shuai; Zhou, Xiang; Yin, Hongyan; Li, Biao; Zhang, Yifan

2014-04-01

93

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. PMID:20304764

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

2010-01-01

94

Sucrose Loading in Isolated Veins of Pisum sativum: Regulation by Abscisic Acid, Gibberellic Acid, and Cell Turgor.  

PubMed

Enzymatically isolated vein networks from mature pea (Pisum sativum L. cv Alaska) leaves were employed to investigate the properties of sucrose loading and the effect of phytohormones and cell turgor on this process. The sucrose uptake showed two components: a saturable and a first-order kinetics system. The high affinity system (K(m), 3.3 millimolar) was located at the plasmalemma (p-chloromercuriphenylsulfonic acid and orthovanadate sensitivity). Further characterization of this system, including pH dependence and effects of energy metabolism inhibitors, supported the H(+)-sugar symport concept for sucrose loading. Within a physiological range (0.1-100 micromolar) and after 90 min, abscisic acid (ABA) inhibited and gibberellic acid (GA(3)) promoted 1 millimolar sucrose uptake. These responses were partially (ABA) or totally (GA(3)) turgor-dependent. In experiments of combined hormonal treatments, ABA counteracted the GA(3) positive effects on sucrose uptake. The abolishment of these responses by p-chloromercuriphenylsulfonic acid and experiments on proton flux suggest that both factors (cell turgor and hormones) are modulating the H(+) ATPase plasmalemma activity. The results are discussed in terms of their physiological relevance. PMID:16667007

Estruch, J J; Peretó, J G; Vercher, Y; Beltrán, J P

1989-09-01

95

Sucrose Loading in Isolated Veins of Pisum sativum: Regulation by Abscisic Acid, Gibberellic Acid, and Cell Turgor 1  

PubMed Central

Enzymatically isolated vein networks from mature pea (Pisum sativum L. cv Alaska) leaves were employed to investigate the properties of sucrose loading and the effect of phytohormones and cell turgor on this process. The sucrose uptake showed two components: a saturable and a first-order kinetics system. The high affinity system (Km, 3.3 millimolar) was located at the plasmalemma (p-chloromercuriphenylsulfonic acid and orthovanadate sensitivity). Further characterization of this system, including pH dependence and effects of energy metabolism inhibitors, supported the H+-sugar symport concept for sucrose loading. Within a physiological range (0.1-100 micromolar) and after 90 min, abscisic acid (ABA) inhibited and gibberellic acid (GA3) promoted 1 millimolar sucrose uptake. These responses were partially (ABA) or totally (GA3) turgor-dependent. In experiments of combined hormonal treatments, ABA counteracted the GA3 positive effects on sucrose uptake. The abolishment of these responses by p-chloromercuriphenylsulfonic acid and experiments on proton flux suggest that both factors (cell turgor and hormones) are modulating the H+ ATPase plasmalemma activity. The results are discussed in terms of their physiological relevance. Images Figure 1 PMID:16667007

Estruch, Juan Jose; Pereto, Juli G.; Vercher, Yolanda; Beltran, Jose Pio

1989-01-01

96

Energetics of Amino Acid Uptake by Vicia faba Leaf Tissues 1  

PubMed Central

The uptake of [U-14C]threonine and of (?-14C]aminoisobutyrate (?-AIB) by Vicia faba leaf discs is strongly pH dependent (optimum: pH 4.0) and exhibits biphasic saturation kinetics. Kinetics of ?-AIB uptake at different pH values indicate that acidic pH values decrease the Km of the carriers while the maximal velocity remains nearly unaffected. Similar results were obtained for both system 1 (from 0.5 to 5 millimolar) and system 2 (from 20 to 100 millimolar). After addition of amino acids to a medium containing leaf fragments, alkalinizations depending both on the amino acid added and on its concentration have been recorded. The effects of compounds which increase (fusicoccin) or decrease (uncouplers, ATPase inhibitors, high KCl concentrations) the protonmotive force were studied both on the acidification of the medium and on amino acid uptake by the tissues. There is a close relationship between the time required for the effect of these compounds on the acidification and that needed for inhibition of uptake. Studies with thiol inhibitors show that 0.1 millimolar N-ethylmaleimide preferentially inhibits uptake by the mesophyll whereas 0.1 millimolar parachloromercuribenzenesulfonate affects rather uptake by the veins. New evidence was found which added to the electrophysiological data already supporting the occurrence of proton amino acid symport in leaf tissues, particularly in the veins. Images Fig. 2 Fig. 10 Fig. 12 PMID:16662764

Despeghel, Jean-Pierre; Delrot, Serge

1983-01-01

97

Arabidopsis plants harbouring a mutation in AtSUC2, encoding the predominant sucrose/proton symporter necessary for efficient phloem transport, are able to complete their life cycle and produce viable seed  

PubMed Central

Background and Aims AtSUC2 encodes a sucrose/proton symporter that localizes throughout the collection and transport phloem and is necessary for efficient transport of sucrose from source to sink tissues in Arabidopsis thaliana. Plants harbouring homozygous AtSUC2 null alleles accumulate sugar, starch, and anthocyanin in mature leaves, have severely delayed development and stunted growth and, in previous studies, failed to complete their life cycle by producing viable seed. Methods An AtSUC2 allele with a T-DNA insertion in the second intron was analysed. Full-length transcript from this allele is not produced, and a truncated protein translated from sequences upstream of the insertion site did not catalyse sucrose uptake into yeast, supporting the contention that this is a null allele. Mutant plants were grown in a growth chamber with a diurnal light/dark cycle, and growth patterns recorded. Key Results This allele (SALK_038124, designated AtSUC2-4) has the hallmarks of previously described null alleles but, despite compromised carbon partitioning and growth, produces viable seeds. The onset of flowering was chronologically delayed but occurred at the same point in the plastochron index as wild type. Conclusions AtSUC2 is important for phloem loading and is therefore fundamental to phloem transport and plant productivity, but plants can complete their life cycle and produce viable seed in its absence. Arabidopsis appears to have mechanisms for mobilizing reduced carbon from the phloem into developing seeds independent of AtSUC2. PMID:19789176

Srivastava, Avinash C.; Dasgupta, Kasturi; Ajieren, Eric; Costilla, Gabriella; McGarry, Roisin C.; Ayre, Brian G.

2009-01-01

98

The Paired-Domain Transcription Factor Pax8 Binds to the Upstream Enhancer of the Rat Sodium/Iodide Symporter Gene and Participates in Both Thyroid-Specific and Cyclic-AMP-Dependent Transcription  

PubMed Central

The gene encoding the Na/I symporter (NIS) is expressed at high levels only in thyroid follicular cells, where its expression is regulated by the thyroid-stimulating hormone via the second messenger, cyclic AMP (cAMP). In this study, we demonstrate the presence of an enhancer that is located between nucleotides ?2264 and ?2495 in the 5?-flanking region of the NIS gene and that recapitulates the most relevant aspects of NIS regulation. When fused to either its own or a heterologous promoter, the NIS upstream enhancer, which we call NUE, stimulates transcription in a thyroid-specific and cAMP-dependent manner. The activity of NUE depends on the four most relevant sites, identified by mutational analysis. The thyroid-specific transcription factor Pax8 binds at two of these sites. Mutations that interfere with Pax8 binding also decrease transcriptional activity of the NUE. Furthermore, expression of Pax8 in nonthyroid cells results in transcriptional activation of NUE, strongly suggesting that the paired-domain protein Pax8 plays an important role in NUE activity. The NUE responds to cAMP in both protein kinase A-dependent and -independent manners, indicating that this enhancer could represent a novel type of cAMP responsive element. Such a cAMP response requires Pax8 but also depends on the integrity of a cAMP responsive element (CRE)-like sequence, thus suggesting a functional interaction between Pax8 and factors binding at the CRE-like site. PMID:10022892

Ohno, Makoto; Zannini, Mariastella; Levy, Orlie; Carrasco, Nancy; di Lauro, Roberto

1999-01-01

99

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

2011-12-01

100

Molecular transport machinery involved in orchestrating luminal acid-induced duodenal bicarbonate secretion in vivo  

PubMed Central

The duodenal villus brush border membrane expresses several ion transporters and/or channels, including the solute carrier 26 anion transporters Slc26a3 (DRA) and Slc26a6 (PAT-1), the Na+/H+ exchanger isoform 3 (NHE3), as well as the anion channels cystic fibrosis transmembrane conductance regulator (CFTR) and Slc26a9. Using genetically engineered mouse models lacking Scl26a3, Slc26a6, Slc26a9 or Slc9a3 (NHE3), the study was carried out to assess the role of these transporters in mediating the protective duodenal bicarbonate secretory response (DBS-R) to luminal acid; and to compare it to their role in DBS-R elicited by the adenylyl cyclase agonist forskolin. While basal DBS was reduced in the absence of any of the three Slc26 isoforms, the DBS-R to forskolin was not altered. In contrast, the DBS-R to a 5 min exposure to luminal acid (pH 2.5) was strongly reduced in the absence of Slc26a3 or Slc26a9, but not Slc26a6. CFTR inhibitor [CFTR(Inh)-172] reduced the first phase of the acid-induced DBS-R, while NHE3 inhibition (or knockout) abolished the sustained phase of the DBS-R. Luminal acid exposure resulted in the activation of multiple intracellular signalling pathways, including SPAK, AKT and p38 phosphorylation. It induced a biphasic trafficking of NHE3, first rapidly into the brush border membrane, followed by endocytosis in the later stage. We conclude that the long-lasting DBS-R to luminal acid exposure activates multiple duodenocyte signalling pathways and involves changes in trafficking and/or activity of CFTR, Slc26 isoforms Slc26a3 and Slc26a9, and NHE3. PMID:24018950

Singh, Anurag Kumar; Liu, Yongjian; Riederer, Brigitte; Engelhardt, Regina; Thakur, Basant Kumar; Soleimani, Manoocher; Seidler, Ursula

2013-01-01

101

A pyruvate-proton symport and an H+-ATPase regulate the intracellular pH of Trypanosoma brucei at different stages of its life cycle.  

PubMed

Regulation of intracellular pH (pH(i)) and H(+) efflux were investigated in Trypanosoma brucei bloodstream and procyclic trypomastigotes using the fluorescent dyes 2', 7'-bis-(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF) acetoxymethyl ester and free BCECF respectively. pH(i) in bloodstream and procyclic trypomastigotes was 7.47+/-0.06 and 7. 53+/-0.07 respectively. Differences in the mechanisms for the regulation of pH(i) were noted between bloodstream and procyclic forms. Procyclic trypomastigotes maintained their pH(i) at neutral over a wide range of external pH values from 6 to 8, and in the absence of K(+) or Na(+). The H(+)-ATPase inhibitors N, N'-dicyclohexylcarbodi-imide (DCCD), diethylstilboestrol and N-ethylmaleimide substantially decreased the steady-state pH(i) and inhibited its recovery from acidification. The rate of H(+) efflux in these forms was determined to be 62+/-6.5 nmol/min per mg of protein, and was substantially decreased by H(+)-ATPase inhibitors. The data support the presence of an H(+)-ATPase as the major regulator of pH(i) in procyclic trypomastigotes. In contrast, bloodstream trypomastigotes were unable to maintain a neutral pH under acidic conditions, and their steady-state pH(i) and recovery from acidification were unaffected by H(+)-ATPase inhibitors, except for DCCD (100 microM). Their steady-state pH(i) was markedly decreased in glucose-free buffer or by >/=10 mM pyruvate, whereas procyclic trypomastigotes were unaffected by similar treatments. The rate of H(+) efflux in bloodstream trypomastigotes was 534+/-38 nmol/min per mg of protein, and was decreased in the absence of glucose and by the addition of pyruvate or DCCD. Pyruvate efflux in these forms was calculated to be 499+/-34 nmol/min per mg of protein, and was significantly inhibited by DCCD, 4, 4'-di-isothiocyanatodihydrostilbene-2,2'-disulphonic acid and alpha-cyanohydroxycinnamic acid. The pyruvate analogues beta-hydroxypyruvate, 3-bromopyruvate, 3-oxoglutarate, oxaloacetate, 3-oxoisovalerate and 3-oxoisohexanoate significantly decreased pH(i), as well as proton and pyruvate efflux, whereas lactate had only a small effect, and no effect was observed with citrate or fumarate. The inhibition by pyruvate analogues of pyruvate efflux, proton efflux and acidification of pH(i) supports the hypothesis that pyruvate efflux is accompanied by proton efflux and that this is the major pH(i) control mechanism in bloodstream forms. Inhibition by H(+)-ATPase inhibitors of residual H(+) efflux in the absence of glucose or in the presence of high extracellular pyruvate indicates a minor role for H(+)-ATPase(s) in control of pH(i) in bloodstream forms. PMID:10657239

Vanderheyden, N; Wong, J; Docampo, R

2000-02-15

102

A pyruvate-proton symport and an H+-ATPase regulate the intracellular pH of Trypanosoma brucei at different stages of its life cycle.  

PubMed Central

Regulation of intracellular pH (pH(i)) and H(+) efflux were investigated in Trypanosoma brucei bloodstream and procyclic trypomastigotes using the fluorescent dyes 2', 7'-bis-(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF) acetoxymethyl ester and free BCECF respectively. pH(i) in bloodstream and procyclic trypomastigotes was 7.47+/-0.06 and 7. 53+/-0.07 respectively. Differences in the mechanisms for the regulation of pH(i) were noted between bloodstream and procyclic forms. Procyclic trypomastigotes maintained their pH(i) at neutral over a wide range of external pH values from 6 to 8, and in the absence of K(+) or Na(+). The H(+)-ATPase inhibitors N, N'-dicyclohexylcarbodi-imide (DCCD), diethylstilboestrol and N-ethylmaleimide substantially decreased the steady-state pH(i) and inhibited its recovery from acidification. The rate of H(+) efflux in these forms was determined to be 62+/-6.5 nmol/min per mg of protein, and was substantially decreased by H(+)-ATPase inhibitors. The data support the presence of an H(+)-ATPase as the major regulator of pH(i) in procyclic trypomastigotes. In contrast, bloodstream trypomastigotes were unable to maintain a neutral pH under acidic conditions, and their steady-state pH(i) and recovery from acidification were unaffected by H(+)-ATPase inhibitors, except for DCCD (100 microM). Their steady-state pH(i) was markedly decreased in glucose-free buffer or by >/=10 mM pyruvate, whereas procyclic trypomastigotes were unaffected by similar treatments. The rate of H(+) efflux in bloodstream trypomastigotes was 534+/-38 nmol/min per mg of protein, and was decreased in the absence of glucose and by the addition of pyruvate or DCCD. Pyruvate efflux in these forms was calculated to be 499+/-34 nmol/min per mg of protein, and was significantly inhibited by DCCD, 4, 4'-di-isothiocyanatodihydrostilbene-2,2'-disulphonic acid and alpha-cyanohydroxycinnamic acid. The pyruvate analogues beta-hydroxypyruvate, 3-bromopyruvate, 3-oxoglutarate, oxaloacetate, 3-oxoisovalerate and 3-oxoisohexanoate significantly decreased pH(i), as well as proton and pyruvate efflux, whereas lactate had only a small effect, and no effect was observed with citrate or fumarate. The inhibition by pyruvate analogues of pyruvate efflux, proton efflux and acidification of pH(i) supports the hypothesis that pyruvate efflux is accompanied by proton efflux and that this is the major pH(i) control mechanism in bloodstream forms. Inhibition by H(+)-ATPase inhibitors of residual H(+) efflux in the absence of glucose or in the presence of high extracellular pyruvate indicates a minor role for H(+)-ATPase(s) in control of pH(i) in bloodstream forms. PMID:10657239

Vanderheyden, N; Wong, J; Docampo, R

2000-01-01

103

Monensin Inhibition of Na+-Dependent HCO3- Transport Distinguishes It from Na+-Independent HCO3- Transport and Provides Evidence for Na+/HCO3- Symport in the Cyanobacterium Synechococcus UTEX 625.  

PubMed Central

The effect of monensin, an ionophore that mediates Na+/H+ exchange, on the activity of the inorganic carbon transport systems of the cyanobacterium Synechococcus UTEX 625 was investigated using transport assays based on the measurement of chlorophyll a fluorescence emission or 14C uptake. In Synechococcus cells grown in standing culture at about 20 [mu]M CO2 + HCO3-, 50 [mu]M monensin transiently inhibited active CO2 and Na+-independent HCO3- transport, intracellular CO2 and HCO3- accumulation, and photosynthesis in the presence but not in the absence of 25 mM Na+. These activities returned to near-normal levels within 15 min. Transient inhibition was attributed to monensin-mediated intracellular alkalinization, whereas recovery may have been facilitated by cellular mechanisms involved in pH homeostasis or by monensin-mediated H+ uptake with concomitant K+ efflux. In air-grown cells grown at 200 [mu]M CO2 + HCO3- and standing culture cells, Na+-dependent HCO3- transport, intracellular HCO3- accumulation, and photosynthesis were also inhibited by monensin, but there was little recovery in activity over time. However, normal photosynthetic activity could be restored to air-grown cells by the addition of carbonic anhydrase, which increased the rate of CO2 supply to the cells. This observation indicated that of all the processes required to support photosynthesis only Na+-dependent HCO3- transport was significantly inhibited by monensin. Monensin-mediated dissipation of the Na+ chemical gradient between the medium and the cells largely accounted for the decline in the HCO3- accumulation ratio from 751 to 55. The two HCO3- transport systems were further distinguished in that Na+-dependent HCO3- transport was inhibited by Li+, whereas Na+-independent HCO3- transport was not. It is suggested that Na+-dependent HCO3- transport involves an Na+/HCO3- symport mechanism that is energized by the Na+ electrochemical potential. PMID:12232177

Espie, G. S.; Kandasamy, R. A.

1994-01-01

104

Monensin Inhibition of Na+-Dependent HCO3- Transport Distinguishes It from Na+-Independent HCO3- Transport and Provides Evidence for Na+/HCO3- Symport in the Cyanobacterium Synechococcus UTEX 625.  

PubMed

The effect of monensin, an ionophore that mediates Na+/H+ exchange, on the activity of the inorganic carbon transport systems of the cyanobacterium Synechococcus UTEX 625 was investigated using transport assays based on the measurement of chlorophyll a fluorescence emission or 14C uptake. In Synechococcus cells grown in standing culture at about 20 [mu]M CO2 + HCO3-, 50 [mu]M monensin transiently inhibited active CO2 and Na+-independent HCO3- transport, intracellular CO2 and HCO3- accumulation, and photosynthesis in the presence but not in the absence of 25 mM Na+. These activities returned to near-normal levels within 15 min. Transient inhibition was attributed to monensin-mediated intracellular alkalinization, whereas recovery may have been facilitated by cellular mechanisms involved in pH homeostasis or by monensin-mediated H+ uptake with concomitant K+ efflux. In air-grown cells grown at 200 [mu]M CO2 + HCO3- and standing culture cells, Na+-dependent HCO3- transport, intracellular HCO3- accumulation, and photosynthesis were also inhibited by monensin, but there was little recovery in activity over time. However, normal photosynthetic activity could be restored to air-grown cells by the addition of carbonic anhydrase, which increased the rate of CO2 supply to the cells. This observation indicated that of all the processes required to support photosynthesis only Na+-dependent HCO3- transport was significantly inhibited by monensin. Monensin-mediated dissipation of the Na+ chemical gradient between the medium and the cells largely accounted for the decline in the HCO3- accumulation ratio from 751 to 55. The two HCO3- transport systems were further distinguished in that Na+-dependent HCO3- transport was inhibited by Li+, whereas Na+-independent HCO3- transport was not. It is suggested that Na+-dependent HCO3- transport involves an Na+/HCO3- symport mechanism that is energized by the Na+ electrochemical potential. PMID:12232177

Espie, G. S.; Kandasamy, R. A.

1994-04-01

105

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

106

Rosmarinic acid  

Microsoft Academic Search

Rosmarinic acid is an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid. It is commonly found in species of the Boraginaceae and the subfamily Nepetoideae of the Lamiaceae. However, it is also found in species of other higher plant families and in some fern and hornwort species. Rosmarinic acid has a number of interesting biological activities, e.g. antiviral, antibacterial, antiinflammatory and

Maike Petersen; Monique S. J Simmonds

2003-01-01

107

Shikimic Acid  

NSDL National Science Digital Library

The molecule for this month comes from the article Isolation of Shikimic Acid from Star Aniseed by Richard Payne and Michael Edmonds. Shikimic acid plays a key role in the biosynthesis of many important natural products including aromatic amino acids, alkaloids, phenolics, and phenylpropanoids. It plays such an important role that one of the key biosynthetic pathways is referred to as the shikimate pathway.

108

Acid rain  

Microsoft Academic Search

For the past five years, scientists at the Univ. of Colorado have been measuring acid precipitation in a subalpine watershed of the Colorado Rockies. Their measurements of snow and rain and creek water show a strong trend of increasing acidity that is traceable to the chemical reactions of burning fossil fuels. Possible effects of acid precipitation on the watershed's aquatic

Caile

2009-01-01

109

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. PMID:23063128

Fedorenko, Andriy; Lishko, Polina V.

2013-01-01

110

Rosmarinic acid.  

PubMed

Rosmarinic acid is an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid. It is commonly found in species of the Boraginaceae and the subfamily Nepetoideae of the Lamiaceae. However, it is also found in species of other higher plant families and in some fern and hornwort species. Rosmarinic acid has a number of interesting biological activities, e.g. antiviral, antibacterial, antiinflammatory and antioxidant. The presence of rosmarinic acid in medicinal plants, herbs and spices has beneficial and health promoting effects. In plants, rosmarinic acid is supposed to act as a preformed constitutively accumulated defence compound. The biosynthesis of rosmarinic acid starts with the amino acids L-phenylalanine and L-tyrosine. All eight enzymes involved in the biosynthesis are known and characterised and cDNAs of several of the involved genes have been isolated. Plant cell cultures, e.g. from Coleus blumei or Salvia officinalis, accumulate rosmarinic acid in amounts much higher than in the plant itself (up to 36% of the cell dry weight). For this reason a biotechnological production of rosmarinic acid with plant cell cultures has been proposed. PMID:12482446

Petersen, Maike; Simmonds, Monique S J

2003-01-01

111

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

112

Tranexamic Acid  

MedlinePLUS

Tranexamic acid comes as a tablet to take by mouth. It is usually taken with or without food three times a day for up to 5 days during monthly menstruation. You should begin taking this medication each month when your period starts. Do not take tranexamic acid when you do not have a period. Take ...

113

Acid rain  

Microsoft Academic Search

The causes and effects of acid rain are detailed. Sulfur dioxide and nitrogen dioxide emissions from anthropogenic sources are the primary causative agents. These emissions are transported over long distances and transformed into sulfates and nitrates and washed out of the atmosphere. Trends in acidity in precipitation water are reviewed for eastern portions of Canada and the U.S. Adverse effects

R. E. Ghelardi; B. L. Murphy

2009-01-01

114

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

115

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

116

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.

Bailey, Christina; Kohlen, Corinne

2010-02-10

117

Asparagusic acid.  

PubMed

Asparagusic acid (1,2-dithiolane-4-carboxylic acid) is a simple sulphur-containing 5-membered heterocyclic compound that appears unique to asparagus, though other dithiolane derivatives have been identified in non-food species. This molecule, apparently innocuous toxicologically to man, is the most probable culprit responsible for the curious excretion of odorous urine following asparagus ingestion. The presence of the two adjacent sulphur atoms leads to an enhanced chemical reactivity, endowing it with biological properties including the ability to substitute potentially for ?-lipoic acid in ?-keto-acid oxidation systems. This brief review collects the scattered data available in the literature concerning asparagusic acid and highlights its properties, intermediary metabolism and exploratory applications. PMID:24099657

Mitchell, Stephen C; Waring, Rosemary H

2014-01-01

118

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. PMID:16666897

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

1989-01-01

119

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

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 (Deltapsi and DeltapH) 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 alpha-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 Deltapsi and DeltapH (10 micromolar carbonylcyanide-m-chlorophenyl hydrazone) or only Deltapsi (0.1 molar KCl). The absorption of alpha-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. PMID:16666897

Renault, S; Despeghel-Caussin, C; Bonnemain, J L; Delrot, S

1989-07-01

120

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

121

Acid fog  

SciTech Connect

Fog in areas of southern California previously thought to be pollution-free has been shown to have a pH as low as 1.69. It has been found to be most acidic after smoggy days, suggesting that it forms on the aerosol associated with the previously exiting smog. Studies on Whiteface Mountain in the Adirondacks show that fog water is often 10 times as acidic as rainwater. As a result of their studies, California plans to spend $4 million on acid deposition research in the coming year. (JMT)

Hileman, B.

1983-03-01

122

ACID RAIN  

EPA Science Inventory

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 diff...

123

Acidic precipitation  

SciTech Connect

At the International Symposium on Acidic Precipitation, over 400 papers were presented, and nearly 200 of them are included here. They provide an overview of the present state of the art of acid rain research. The Conference focused on atmospheric science (monitoring, source-receptor relationships), aquatic effects (marine eutrophication, lake acidification, impacts on plant and fish populations), and terrestrial effects (forest decline, soil acidification, etc.).

Martin, H.C.

1987-01-01

124

Proton-symport of L-valine in plasma membrane vesicles isolated from leaves of the wild-type and the Val(r)-2 mutant of Nicotiana tabacum L.  

PubMed

Transport of amino acids across the plasma membranes of various cell types is a key process in controlling the nitrogen balance of leaves. We studied the transport of the neutral amino acid L-valine into plasma membrane vesicles obtained by aqueous polymer two-phase partitioning of a microsomal fraction isolated from leaves of the wild-type and the Val(r)-2 mutant of tobacco (Nicotiana tabacum L.). Initial influxes were determined after the imposition of a pH-gradient (DeltapH, inside alkaline) and/or an electrical gradient (Deltapsi, inside negative) across the vesicle membrane. The initial magnitudes of the imposed gradients were DeltapH=2 and Deltapsi=-68 mV. In vesicles from the wild-type, the DeltapH-dependent valine influx could be analysed into a high-affinity (Km approximately 20 microM) and a low-affinity (Km approximately 3 mM) component. The influx of valine by the low-affinity system was stimulated about twofold, and that by the high-affinity system more than sixfold by the imposition of Deltapsi. This strong stimulation of the high-affinity system may indicate that it transports 2H+/amino acid. In the Val(r)-2 mutant the high-affinity component appeared to be completely absent. PMID:11092905

Borstlap, A C; Schuurmans, J A

2000-11-01

125

Acid sphingomyelinase.  

PubMed

The enzyme acid sphingomyelinase catalyzes the hydrolysis of sphingomyelin to ceramide. The importance of the enzyme for cell functions was first recognized in Niemann-Pick disease type A and B, the genetic disorders with a massive accumulation of sphingomyelin in many organs. Studies in the last years demonstrated that the enzyme also has an important role in cell signalling. Thus, the acid sphingomyelinase has a central function for the re-organization of molecules within the cell upon stimulation and thereby for the response of cells to stress and the induction of cell death but also proliferation and differentiation. Here, we discuss the current state of the art of the structure, regulation, and function of the acid sphingomyelinase. PMID:23579450

Henry, Brian; Ziobro, Regan; Becker, Katrin Anne; Kolesnick, Richard; Gulbins, Erich

2013-01-01

126

Salicylic acids  

PubMed Central

Salicylic acid is well known phytohormone, emerging recently as a new paradigm of an array of manifestations of growth regulators. The area unleashed yet encompassed the applied agriculture sector to find the roles to strengthen the crops against plethora of abiotic and biotic stresses. The skipped part of integrated picture, however, was the evolutionary insight of salicylic acid to either allow or discard the microbial invasion depending upon various internal factors of two interactants under the prevailing external conditions. The metabolic status that allows the host invasion either as pathogenesis or symbiosis with possible intermediary stages in close systems has been tried to underpin here. PMID:22301975

Hayat, Shamsul; Irfan, Mohd; Wani, Arif; Nasser, Alyemeni; Ahmad, Aqil

2012-01-01

127

Acid Stomach  

NSDL National Science Digital Library

This Science NetLinks lesson is intended for a high-school, introductory chemistry class or health class. The lesson begins with an article on the history of the development of aspirin. Students will then complete a lab that compares the reaction of regular aspirin, buffered aspirin, and enteric aspirin in neutral, acidic, and basic solutions. They will then analyze the results of the experiment to gain insight into how this information was used by researchers to solve some of the problems associated with aspirin. To complete the lesson, students must understand acids and bases.

Science Netlinks;

2003-08-07

128

Acid rain  

Microsoft Academic Search

The book describes numerous environmental problems which are the result of emissions from coal combustion, petroleum products combustion, petroleum refining, and non-ferrous smelting. The effects of acid rain on soils, plants, water, aquatic ecosystems, and building materials are described. Studies are discussed which show that wind currents are carrying emissions to locations far from the source, with social, economic, and

Ostmann; R. Jr

1982-01-01

129

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

130

Domoic Acid  

NSDL National Science Digital Library

This highly detailed chemical information page features domoic acid, a toxin associated with Amnesic shellfish poisoning and naturally produced by the red algae Chondria armata and diatoms of the genus Pseudo-nitzschia. Created by the International Programme on Chemical Safety, this web page organizes information under the following sections: Name, Summary, Physio-Chemical Properties, Uses, Routes of Entry, Kinetics, Toxicology, Toxicological and Biomedical Investigations, Clinical Effects, Management, Illustrative Cases, Additional Information, References, and Authors.

Inchem; Safety, International P.

131

Scattering of He atoms from surface defects by grazingangle diffraction beams D. Far as, 2 M. Patting, 1 K.H. Rieder, 1 and J. R. Manson 3  

E-print Network

Scattering of He atoms from surface defects by grazing­angle diffraction beams D. Far� â?? as, 2 M the scattering of He atoms from surfaces can be observed at grazing final angles of up to # f #90° with respect to the surface normal. For He atom scattering from Rh#311# under conditions in which a diffraction beam exits

Manson, Joseph R.

132

Acid Ocean  

NSDL National Science Digital Library

The I2I-Acid Ocean virtual lab is an e-learning activity where students become virtual scientists studying the impact of ocean acidification on sea urchin larval growth. Students recreate a real, up-to-date climate change experiment. They also learn important general scientific principles, such as the importance of sample size and numbers of replicates, and discuss what this research into a specific impact of climate change may mean for the future of our oceans. There is a French translation available.

133

The SLC36 family of proton-coupled amino acid transporters and their potential role in drug transport  

PubMed Central

Members of the solute carrier (SLC) 36 family are involved in transmembrane movement of amino acids and derivatives. SLC36 consists of four members. SLC36A1 and SLC36A2 both function as H+-coupled amino acid symporters. SLC36A1 is expressed at the luminal surface of the small intestine but is also commonly found in lysosomes in many cell types (including neurones), suggesting that it is a multipurpose carrier with distinct roles in different cells including absorption in the small intestine and as an efflux pathway following intralysosomal protein breakdown. SLC36A1 has a relatively low affinity (Km 1–10 mM) for its substrates, which include zwitterionic amino and imino acids, heterocyclic amino acids and amino acid-based drugs and derivatives used experimentally and/or clinically to treat epilepsy, schizophrenia, bacterial infections, hyperglycaemia and cancer. SLC36A2 is expressed at the apical surface of the human renal proximal tubule where it functions in the reabsorption of glycine, proline and hydroxyproline. SLC36A2 also transports amino acid derivatives but has a narrower substrate selectivity and higher affinity (Km 0.1–0.7 mM) than SLC36A1. Mutations in SLC36A2 lead to hyperglycinuria and iminoglycinuria. SLC36A3 is expressed only in testes and is an orphan transporter with no known function. SLC36A4 is widely distributed at the mRNA level and is a high-affinity (Km 2–3 µM) transporter for proline and tryptophan. We have much to learn about this family of transporters, but from current knowledge, it seems likely that their function will influence the pharmacokinetic profiles of amino acid-based drugs by mediating transport in both the small intestine and kidney. LINKED ARTICLES This article is part of a themed section on Transporters. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2011.164.issue-7 PMID:21501141

Thwaites, David T; Anderson, Catriona MH

2011-01-01

134

Methylmalonic acid blood test  

MedlinePLUS

... acid is a substance produced when proteins (called amino acids) in the body break down. A test can ... Cederbaum S, Berry GT. Inborn errors of carbohydrate, ammonia, amino acid, and organic acid metabolism. In: Gleason CA, Devaskar ...

135

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

136

Brnsted Acids The Strongest Isolable Acid**  

E-print Network

Brønsted Acids The Strongest Isolable Acid** Mark Juhasz, Stephan Hoffmann, Evgenii Stoyanov, Kee-Chan Kim, and Christopher A. Reed* Acids based on carborane anions as conjugate bases (Figure 1) are a new class of Brønsted (protic) acids, notable for their "strong yet gentle" qualities.[1] For example

Reed, Christopher A.

137

Acid rain  

SciTech Connect

Acid rain, says Boyle is a chemical leprosy eating into the face of North America and Europe, perhaps the major ecological problem of our time. Boyle describes the causes and scope of the phenomenon; the effects on man, wildlife, water, and our cultural heritage. He probes the delays of politicians and the frequent self-serving arguments advanced by industry in the face of what scientists have proved. The solutions he offers are to strengthen the Clean Air Act and require emission reductions that can be accomplished by establishing emission standards on a regional or bubble basis, burn low-sulfur coal, install scrubbers at critical plants, and invest in alternative energy sources. 73 references, 1 figure.

Boyle, R.H.; Boyle, R.A.

1983-01-01

138

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

139

Rediscovering Arsenoacetic Acid.  

E-print Network

??Arsonoacetic acid, H?O?As¹CH?COOH, and arsenoacetic acid, punitively [AsVCH?COOH]? have been synthesised according to historical literature methods, and have been characterised using modern techniques. Arsonoacetic acid… (more)

Wilson, Peter Stanley

2009-01-01

140

Organic acids tunably catalyze carbonic acid decomposition.  

PubMed

Density functional theory calculations predict that the gas-phase decomposition of carbonic acid, a high-energy, 1,3-hydrogen atom transfer reaction, can be catalyzed by a monocarboxylic acid or a dicarboxylic acid, including carbonic acid itself. Carboxylic acids are found to be more effective catalysts than water. Among the carboxylic acids, the monocarboxylic acids outperform the dicarboxylic ones wherein the presence of an intramolecular hydrogen bond hampers the hydrogen transfer. Further, the calculations reveal a direct correlation between the catalytic activity of a monocarboxylic acid and its pKa, in contrast to prior assumptions about carboxylic-acid-catalyzed hydrogen-transfer reactions. The catalytic efficacy of a dicarboxylic acid, on the other hand, is significantly affected by the strength of an intramolecular hydrogen bond. Transition-state theory estimates indicate that effective rate constants for the acid-catalyzed decomposition are four orders-of-magnitude larger than those for the water-catalyzed reaction. These results offer new insights into the determinants of general acid catalysis with potentially broad implications. PMID:24933150

Kumar, Manoj; Busch, Daryle H; Subramaniam, Bala; Thompson, Ward H

2014-07-10

141

Acid Rain Study Guide.  

ERIC Educational Resources Information Center

Acid rain is a complex, worldwide environmental problem. This study guide is intended to aid teachers of grades 4-12 to help their students understand what acid rain is, why it is a problem, and what possible solutions exist. The document contains specific sections on: (1) the various terms used in conjunction with acid rain (such as acid

Hunger, Carolyn; And Others

142

Formic Acid Mechanical,  

E-print Network

and engineering. Products will range from starch, to polylactic acid, to corn fiber, to motor fuels. ProgressiveFormic Acid Fire Ant Starch Mechanical, Industrial Chemical, Petroleum Biological What Do systems. Fire ants make formic acid. U of I researchers are developing fuel cells that use formic acid (1

Illinois at Urbana-Champaign, University of

143

Sulphuric Acid Manufacture  

Microsoft Academic Search

The raw material for sulphuric acid manufacture is clean SO2 gas. It comes from (i) burning molten by-product sulphur; (ii) roasting or smelting metal sulphide concentrates, and (iii) decomposing contaminated organic chemical process sulphuric acid catalyst. Efficient gas cleaning is required for metallurgical and contaminated acid decomposition gases, especially the former. Sulphuric acid is made from SO2 gas by (i)

W. G. Davenport; M. J. King; B. Rogers; A. Weissenberger

2006-01-01

144

Asphaltene damage in matrix acidizing  

E-print Network

were acidized with three stage treatments of 15% hydrochloric acid (HCl), 12% HCL-3% hydrofluoric acid (HF) and 15% HCL. No additives were used in the acid. Comparisons were made between cores acidized with a variety of saturating fluids. Petrographic...

Hinojosa, Roberto Antonio

2012-06-07

145

Quantity of acid in acid fog  

SciTech Connect

This communication notes the actual magnitude of the acidity in acidic fog particles and suggests a possible line of inquiry into the health effects of such fog so that it can be determined whether a typical fog is detrimental or beneficial relative to dry air.

Deal, W.J.

1983-07-01

146

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

147

Fatty acid analogs  

DOEpatents

In one aspect, a radioactively labeled analog of a fatty acid which is capable of being taken up by mammalian tissue and which exhibits an in vivo beta-oxidation rate below that with a corresponding radioactively labeled fatty acid.

Elmaleh, David R. (Newton Center, MA); Livni, Eli (Brookline, MA)

1985-01-01

148

Plasma amino acids  

MedlinePLUS

Plasma amino acids is a screening test done on infants that looks at the amounts of amino ... Laboratory error High or low amounts of individual plasma amino acids must be considered with other information. ...

149

Citric acid urine test  

MedlinePLUS

... usually done while you are on a normal diet. Ask your health care provider for more information. ... A low level of citric acid may mean renal tubular acidosis and a ... acid levels: A high carbohydrate diet Estrogen therapy Vitamin D

150

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

151

Acid rain agreement  

Microsoft Academic Search

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

R. J. SMITH

1980-01-01

152

[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

153

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

154

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

155

Quantity of acid in acid fog  

SciTech Connect

The chemical composition of fog particles has become of considerable interest, because of both the possibility of interpreting atmospheric- chemistry processes in fog particles in terms of the principles of aqueous chemistry and the potential health effects of species present in fog particles. The acidity of fog particles has received wide attention. This communication noted the actual magnitude of the excess acidity in acidic fog particles and suggested a possible line of inquiry into the health effects of such fog so that it can be determined whether a typical fog is detrimental or beneficial relative to dry air. (DP)

Deal, W.J.

1983-07-01

156

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

157

Abscisic Acid ELISA: Organic Acid Interference 1  

PubMed Central

Consideration must be exercised in determination of buffers and solutions used when carrying out enzyme-linked immunosorbent assays (ELISAs). A commercial monoclonal antibody kit for abscisic acid (Idetek, Inc.) gives significant false-positives with tricarboxylic acid cycle intermediates. The organic acids or contaminants interfered with ELISA assays for ABA as indicated by deviations in the slopes of standard curves of ABA in the organic acids. The interference, in the case of ?-ketoglutarate, was caused by a contaminant. Of the organic buffers tested—Tris, Tricine, and Hepes—only Hepes showed false-positive ABA. In addition, we present data indicating the presence of ABA in commercial mannitol and provide a simple procedure for removal of the ABA. PMID:16667202

Belefant, Helen; Fong, Franklin

1989-01-01

158

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

159

Amino acid analysis  

NASA Technical Reports Server (NTRS)

The process and apparatus for qualitative and quantitative analysis of the amino acid content of a biological sample are presented. The sample is deposited on a cation exchange resin and then is washed with suitable solvents. The amino acids and various cations and organic material with a basic function remain on the resin. The resin is eluted with an acid eluant, and the eluate containing the amino acids is transferred to a reaction vessel where the eluant is removed. Final analysis of the purified acylated amino acid esters is accomplished by gas-liquid chromatographic techniques.

Winitz, M.; Graff, J. (inventors)

1974-01-01

160

EXTRACTIONOFTERVALENTLANTHANIDESWITH ACIDIC ORGANOPHOSPHORUS COMPOUNDS  

Microsoft Academic Search

The equilibrium.extraction behavior for a series of tervalent lanthanide ions (Ln) using a chloroform solution containing di(2-ethyl-hexyl) phosphoric acid (HDEHP), diphenylphosphinic acid (HDPP), dibutylphosphorothioic acid (HDBPT), di-n-octylphosphorodithoic acid (HDOPDT), or di(2-ethylhexyl)phosphorodithioic acid (HDEHPDT), either alone or combined with adduct forming agents is studied. The extracted species are Ln(DEHP) 3(HDEHP) 3, Ln(DPP)3 (HDPP)3, Ln(DBPT)3, and are Ln(DBPT)3(HDERP)3 in the presence of

Shoji Motomizu; Henry Freiser

1985-01-01

161

Selective extraction of succinic acid from binary mixture of succinic acid and acetic acid  

Microsoft Academic Search

In production of succinic acid by fermentation, succinic acid and acetic acid are co-produced. To purify the succinic acid from binary-acid mixture of succinic acid and acetic acid, the tertiary amine-based extraction was used. In 1-octanol, the selectivity for succinic acid was proportional to the chain length of tertiary amine. But, the distribution of acids into organic phase was low

Yeon Ki Hong; Won Hi Hong; Ho Nam Chang

2000-01-01

162

Demospongic Acids Revisited  

PubMed Central

The well-known fatty acids with a ?5,9 unsaturation system were designated for a long period as demospongic acids, taking into account that they originally occurred in marine Demospongia sponges. However, such acids have also been observed in various marine sources with a large range of chain-lengths (C16–C32) and from some terrestrial plants with short acyl chains (C18–C19). Finally, the ?5,9 fatty acids appear to be a particular type of non-methylene-interrupted fatty acids (NMA FAs). This article reviews the occurrence of these particular fatty acids in marine and terrestrial organisms and shows the biosynthetic connections between ?5,9 fatty acids and other NMI FAs. PMID:21116406

Kornprobst, Jean-Michel; Barnathan, Gilles

2010-01-01

163

NRPSs and amide ligases producing homopoly(amino acid)s and homooligo(amino acid)s.  

PubMed

Microorganisms are capable of producing a wide variety of biopolymers. Homopoly(amino acid)s and homooligo(amino acid)s, which are made up of only a single type of amino acid, are relatively rare; in fact, only two homopoly(amino acid)s have been known to occur in nature: poly(?-L-lysine) (?-PL) and poly(?-glutamic acid) (?-PGA). Bacterial enzymes that produce homooligo(amino acid)s, such as L-?-lysine-, L-valine-, L-leucine-, L-isoleucine-, L-methionine-, and L-glutamic acid-oligopeptides and poly(?-l-glutamic acid) (?-PGA) have recently been identified, as well as ?-PL synthetase and ?-PGA synthetase. This article reviews the current knowledge about these unique enzymes producing homopoly(amino acid)s and homooligo(amino acid)s. PMID:23817633

Hamano, Yoshimitsu; Arai, Toshinobu; Ashiuchi, Makoto; Kino, Kuniki

2013-08-01

164

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.

165

Lewis acid organocatalysts.  

PubMed

Abstract 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 degrees 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. PMID:21494948

Sereda, Oksana; Tabassum, Sobia; Wilhelm, René

2010-01-01

166

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

167

Acid Rain Learning Activities  

NSDL National Science Digital Library

These suggestions for activities allow students to learn about acid deposition in new and interactive ways, both in and out of the classroom. The suggestions are for individuals and small groups, the class as a whole, or for field trips. Students may contact local experts about acid rain issues, investigate the energy sources used to generate electricity by their local power companies, collect cartoons about acid rain and air pollution, or play the roles of scientists or interested parties involved in investigations of acid rain issues. Field trip ideas include visiting a local museum or science center to see exhibits or resources on acid rain, and visiting a local cemetary to examine the effects of acid rain on the headstones.

168

Bile Acid Metabolism  

Microsoft Academic Search

\\u000a Bile acids are physiological agents that facilitate biliary secretion of lipids and metabolites, and intestinal absorption\\u000a of fat and nutrients. Bile acids are also signaling molecules that activate nuclear receptors and cell signaling pathways\\u000a to regulate hepatic lipid metabolism and homeostasis. Bile acids are synthesized from cholesterol in the liver, stored in\\u000a the gallbladder, secreted to the intestine and reabsorbed

John Y. L. Chiang

169

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

170

Acid-Base Solutions  

NSDL National Science Digital Library

How do strong and weak acids differ? Use lab tools on your computer to find out! Dip the paper or the probe into solution to measure the pH, or put in the electrodes to measure the conductivity. Then see how concentration and strength affect pH. Can a weak acid solution have the same pH as a strong acid solution?

Simulations, Phet I.; Lancaster, Kelly; Malley, Chris; Loeblein, Patricia; Parson, Robert; Perkins, Kathy

2010-09-01

171

DEOXYRIBONUCLEIC ACID HYBRIDS OF ACETIC ACID BACTERIA  

PubMed Central

De Ley, J. (State University, Ghent, Belgium), and S. Friedman. Deoxyribonucleic acid hybrids of acetic acid bacteria. J. Bacteriol. 88:937–945. 1964.—Deuterated N15-labeled deoxyribonucleic acid (DNA) from Acetobacter aceti (mesoxydans 4) forms hybrids with ordinary DNA from other species of this genus (A. xylinum, A. pasteurianus, A. estunensis, and possibly A. xylinoides) when the guanine plus cytosine base composition does not vary by more than 1 to 2%. Beyond this limit (A. aceti Ch31 and A. muciparus 5) no hybrids are formed. The hybrids are apparently derived from an asymmetrical part of the compositional distribution. The results lend strength to the concept of a genetic species rather than to a division of a genus into sharply separated species, based on small phenotypic differences. Taxonomic implications are discussed. PMID:14219057

De Ley, J.; Friedman, S.

1964-01-01

172

Uric Acid Test  

MedlinePLUS

... purine metabolism . Metastatic cancer, multiple myeloma , leukemias , and cancer chemotherapy can cause increased production of uric acid. Chronic renal disease , acidosis , toxemia of pregnancy , and alcoholism can cause ...

173

Molecular Structure of Fumaric acid  

NSDL National Science Digital Library

Fumaric acid is odorless and colorless or white crystalline powder with a fruit acid taste. Fumaric acid is used as a substitute of tartaric acid in beverages and baking powders and as a replacement for citric acid in fruits drinks. It is also used as antioxidant to prevent rancidity in butter, cheese, powdered milk, and other foodstuff. In addition, fumaric acid is a chemical intermediate in the manufacture of pharmaceuticals, synthetic resins and plastics. Fumaric acid can be prepared by catalytic oxidation of benzene or by bacterial action on glucose and it is involved in the production of energy from food. Fumaric acid (known as trans-butanedioic acid) is the trans isomer of maleic acid (also called cis-butanedioic acid). Fumaric acid is more stable than maleic acid and can be prepared by heating maleic acid.

2004-11-05

174

Regioselective hydroxylation of quinolinic acid, lutidinic acid and isocinchomeronic acid by resting cells of pyridine dicarboxylic acid-degrading microorganisms  

Microsoft Academic Search

Microorganisms aerobically degrading quinolinic acid, lutidinic acid or isocinchomeronic acid were isolated and the microbial regioselective hydroxylation of these pyridine dicarboxylic acids was studied. Alcaligenes sp. UK21 cells converted quinolinic acid into 6-hydroxypicolinic acid, suggesting the involvement of two enzyme reactions catalyzing hydroxylation at position C6 and decarboxylation at position C3 of quinolinic acid. Resting cells of Alcaligenes sp. UK21

A. Uchida; T. Yoshida; M. Ogawa; T. Nagasawa

2003-01-01

175

Neutralizing Acids and Bases  

NSDL National Science Digital Library

In this activity, students will use their knowledge of color changes with red cabbage indicator to neutralize an acidic solution with a base and then neutralize a basic solution with an acid. This website includes a student activity sheet and additional student readings.

2010-01-01

176

(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

177

Acid rain: Controllable?  

Microsoft Academic Search

Acid rain is one of a growing number of environmental issues in which impacts are far removed from the source o f the irritants. Those who suffer may differ in geographical area from those who benefit from the activity which releases pollution to the atmosphere. Like the issue concerning the depletion of ozone by manufactured chemicals, the acid rain issue

Lester Machta

1983-01-01

178

Mounting acid rain  

Microsoft Academic Search

The incidence of acid rain at some distance from the initial source of pollution is expected to increase as more plants are converted to burn coal and stacks are built higher to relieve local pollution problems. The alkaline soils of the West neutralize most of the effects of acid rain, making the problem less acute than in the eastern US.

1979-01-01

179

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...

180

Iodinated humic acids  

NASA Astrophysics Data System (ADS)

Humic acids are iodinated by elemental iodine and, if the iodine is present as iodide, by peroxidase-mediated reactions. It is demonstrated that iodination of humic acids leads to a product with a uniform distribution of iodine. It could not be unambiguously verified whether the enzymatically mediated iodination is a direct reaction between a peroxidase-iodine complex and the humic acid molecule or a two-step reaction in which the enzyme creates elemental iodine, which consecutively reacts with the humic acid. Based on a simple model of a reaction between sites in the humic acids available for iodination and the electrophilic iodinating species, it was concluded that the reaction should be described as an equilibrium with a logarithmic equilibrium constant of approximately 4. The number of sites available for iodination was, in the humic acids studied, determined to be approximately 4×10-4 per gram humic acid. The different parameters influencing the enzymatically controlled iodination of humic acids are discussed.

Christiansen, Jesper V.; Carlsen, Lars

181

Controlling acid rain  

E-print Network

High concentrations of sulfuric and nitric acid in raTn fn the northeastern USA are caused by the large scale combustion of fossil fuels within this region. Average precipitation acidity is pH 4.2, but spatial and temporal ...

Fay, James A.

1983-01-01

182

Bile acid transporters  

PubMed Central

In liver and intestine, transporters play a critical role in maintaining the enterohepatic circulation and bile acid homeostasis. Over the past two decades, there has been significant progress toward identifying the individual membrane transporters and unraveling their complex regulation. In the liver, bile acids are efficiently transported across the sinusoidal membrane by the Na+ taurocholate cotransporting polypeptide with assistance by members of the organic anion transporting polypeptide family. The bile acids are then secreted in an ATP-dependent fashion across the canalicular membrane by the bile salt export pump. Following their movement with bile into the lumen of the small intestine, bile acids are almost quantitatively reclaimed in the ileum by the apical sodium-dependent bile acid transporter. The bile acids are shuttled across the enterocyte to the basolateral membrane and effluxed into the portal circulation by the recently indentified heteromeric organic solute transporter, OST?-OST?. In addition to the hepatocyte and enterocyte, subgroups of these bile acid transporters are expressed by the biliary, renal, and colonic epithelium where they contribute to maintaining bile acid homeostasis and play important cytoprotective roles. This article will review our current understanding of the physiological role and regulation of these important carriers. PMID:19498215

Dawson, Paul A.; Lan, Tian; Rao, Anuradha

2009-01-01

183

ACID AEROSOLS ISSUE PAPER  

EPA Science Inventory

The report evaluates scientific information on direct health effects associated with exposure to acid aerosols. The present report is not intended as a complete and detailed review of all literature pertaining to acid aerosols. Rather, an attempt has been made to focus on the eva...

184

Lead-acid batteries  

Microsoft Academic Search

A method of producing a lead-acid battery capable of activation by the addition of electrolyte thereto, comprises the steps of: starting with a battery container accommodating at least one pack of battery plate grids having insulating separators interposed between adjacent grids, each of said grids carrying the lead-acid battery paste required to produce a positive or a negative battery plate

J. A. Bant; V. J. Raban

1980-01-01

185

Urobilinogen AscorbicAcid  

E-print Network

Date Lot # Bilirubin Urobilinogen Ketone AscorbicAcid Glucose Protein Blood pH Nitrite Leukocytes Specific Gravity hCG: Method Lot # Acetest® (Ketone): Lot # Clinitest® (Glucose): Lot # Ictotest®(Bilirubin AND DATA ENTRY FORMS #12;Date Lot # Bilirubin Urobilinogen Ketone AscorbicAcid Glucose Protein Blood p

Rodriguez, Carlos

186

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

187

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.

188

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. PMID:15528496

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

2004-01-01

189

Conjugated Fatty Acid Synthesis  

PubMed Central

Conjugated linolenic acids (CLNs), 18:3 ?9,11,13, lack the methylene groups found between the double bonds of linolenic acid (18:3 ?9,12,15). CLNs are produced by conjugase enzymes that are homologs of the oleate desaturases FAD2. The goal of this study was to map the domain(s) within the Momordica charantia conjugase (FADX) responsible for CLN formation. To achieve this, a series of Momordica FADX-Arabidopsis FAD2 chimeras were expressed in the Arabidopsis fad3fae1 mutant, and the transformed seeds were analyzed for the accumulation of CLN. These experiments identified helix 2 and the first histidine box as a determinant of conjugase product partitioning into punicic acid (18:3 ?9cis,11trans,13cis) or ?-eleostearic acid (18:3 ?9cis,11trans,13trans). This was confirmed by analysis of a FADX mutant containing six substitutions in which the sequence of helix 2 and first histidine box was converted to that of FAD2. Each of the six FAD2 substitutions was individually converted back to the FADX equivalent identifying residues 111 and 115, adjacent to the first histidine box, as key determinants of conjugase product partitioning. Additionally, expression of FADX G111V and FADX G111V/D115E resulted in an approximate doubling of eleostearic acid accumulation to 20.4% and 21.2%, respectively, compared with 9.9% upon expression of the native Momordica FADX. Like the Momordica conjugase, FADX G111V and FADX D115E produced predominantly ?-eleostearic acid and little punicic acid, but the FADX G111V/D115E double mutant produced approximately equal amounts of ?-eleostearic acid and its isomer, punicic acid, implicating an interactive effect of residues 111 and 115 in punicic acid formation. PMID:22451660

Rawat, Richa; Yu, Xiao-Hong; Sweet, Marie; Shanklin, John

2012-01-01

190

Total syntheses of cis-cyclopropane fatty acids: dihydromalvalic acid, dihydrosterculic acid, lactobacillic acid, and 9,10-methylenehexadecanoic acid.  

PubMed

cis-Cyclopropane fatty acids (cis-CFAs) are widespread constituents of the seed oils of subtropical plants, membrane components of bacteria and protozoa, and the fats and phospholipids of animals. We describe a systematic approach to the synthesis of enantiomeric pairs of four cis-CFAs: cis-9,10-methylenehexadecanoic acid, lactobacillic acid, dihydromalvalic acid, and dihydrosterculic acid. The approach commences with Rh2(OAc)4-catalyzed cyclopropenation of 1-octyne and 1-decyne, and hinges on the preparative scale chromatographic resolution of racemic 2-alkylcycloprop-2-ene-1-carboxylic acids using a homochiral Evan's auxiliary. Saturation of the individual diastereomeric N-cycloprop-2-ene-1-carbonylacyloxazolidines, followed by elaboration to alkylcyclopropylmethylsulfones, allowed Julia-Kocienski olefination with various ?-aldehyde-esters. Finally, saponification and diimide reduction afforded the individual cis-CFA enantiomers. PMID:25321346

Shah, Sayali; White, Jonathan M; Williams, Spencer J

2014-12-14

191

Synthesis of (+)- and (?)-Phaselic Acid  

Microsoft Academic Search

The synthesis of both enantiomers of phaselic acid (2-O-caffeoylmalate) is described. The previously unreported acetate protected caffeic acid anhydride was used with appropriately protected malic acid derivatives as coupling partners to provide fully protected phaselic acid. Sequential unmasking of the protecting groups afforded phaselic acid in an acceptable overall yield.

Wayne E. Zeller

2012-01-01

192

Sulfuric Acid on Europa  

NASA Technical Reports Server (NTRS)

Frozen sulfuric acid on Jupiter's moon Europa is depicted in this image produced from data gathered by NASA's Galileo spacecraft. The brightest areas, where the yellow is most intense, represent regions of high frozen sulfuric acid concentration. Sulfuric acid is found in battery acid and in Earth's acid rain.

This image is based on data gathered by Galileo's near infrared mapping spectrometer.

Europa's leading hemisphere is toward the bottom right, and there are enhanced concentrations of sulfuric acid in the trailing side of Europa (the upper left side of the image). This is the face of Europa that is struck by sulfur ions coming from Jupiter's innermost moon, Io. The long, narrow features that crisscross Europa also show sulfuric acid that may be from sulfurous material extruded in cracks.

Galileo, launched in 1989, has been orbiting Jupiter and its moons since December 1995. JPL manages the Galileo mission for NASA's Office of Space Science, Washington DC. JPL is a division of the California Institute of Technology, Pasadena, CA.

1999-01-01

193

Acid recovery from waste sulfuric acid by diffusion dialysis  

Microsoft Academic Search

In the process of sulfuric acid production from pyrite, there is a lot of waste acid produced in fume washing with dilute\\u000a acid. Acid recovery from this sort of waste sulfuric acid by diffusion dialysis is studied in the paper. The mass transfer\\u000a dialysis coefficient of sulfuric acid of the membrane AFX is measured, the effect of the flowrate of

Guiqing Zhang; Qixiu Zhang; Kanggen Zhou

1999-01-01

194

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. PMID:16664007

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

1985-01-01

195

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

196

A Phosphoribosylanthranilate Transferase Gene Is Defective in Blue Fluorescent Arabidopsis thaliana Tryptophan Mutants 1  

PubMed Central

An Arabidopsis thaliana gene encoding phosphoribosylanthranilate transferase is shown to be the gene that is defective in blue fluorescent trp1 mutant plants. This gene, named PAT1, was isolated using an A. thaliana cDNA clone that suppressed an Escherichia coli trpD? mutation. The PAT1 coding region is homologous to those for the phosphoribosylanthranilate transferases from many microorganisms. Unlike other genes involved in aromatic amino acid biosynthesis in A. thaliana, PAT1 appears to be a single-copy gene. PAT1 was demonstrated to be the gene that is defective in blue fluorescent trp1 mutants by two methods: genetic complementation in transgenic plants and genetic mapping studies. This is the first report of cloning a plant phosphoribosylanthranilate transferase gene. The PAT1 gene should prove useful as a selectable marker for transformation or a visible reporter of gene expression when used in conjunction with trp1 plants. Images Figure 2 Figure 4 Figure 6 Figure 7 PMID:16653032

Rose, Alan B.; Casselman, Amy L.; Last, Robert L.

1992-01-01

197

Stomach acid test  

MedlinePLUS

Gastric acid secretion test ... The test is done after a period of not eating so that fluid is all that remains in the ... the stomach through the esophagus (food pipe). To test the ability of the cells in the stomach ...

198

ACID RAIN CONTROL OPTIONS  

EPA Science Inventory

The paper discusses acid rain control options available to the electric utility industry. They include coal switching, flue gas desulfurization, and such emerging lower cost technologies as Limestone Injection Multistage Burners (LIMB) and Advanced Silicate (ADVACATE) both develo...

199

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

200

Folic acid in diet  

MedlinePLUS

... leafy vegetables Dried beans and peas (legumes) Citrus fruits and juices Fortified means that vitamins have been added to the food. Many foods are now fortified with folic acid, including enriched breads, cereals, flours, cornmeals, pastas, rice, ...

201

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 ...

202

(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

203

Aminolevulinic Acid Topical  

MedlinePLUS

... under the skin that result from exposure to sunlight and can develop into skin cancer) of the ... acid will make your skin very sensitive to sunlight (likely to get sunburn). Avoid exposure of treated ...

204

Fatty Acid Carcass Mapping  

E-print Network

FATTY ACID CARCASS MAPPING A Thesis by STACEY NICOLE TURK Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 2008... Major Subject: Animal Science FATTY ACID CARCASS MAPPING A Thesis by STACEY NICOLE TURK Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE...

Turk, Stacey N.

2010-01-14

205

Acid-base chemistry  

SciTech Connect

The book is not a research compendium and there are no references to the literature. It is a teaching text covering the entire range of undergraduate subject matter dealing with acid-base chemistry (some of it remotely) as taught in inorganic, analytical, and organic chemistry courses. The excellent chapters VII through IX deal in detail with the quantitative aspects of aqueous acid-base equilibria (salt hydrolysis and buffer, titrations, polyprotic and amphoteric substances).

Hand, C.W.; Blewit, H.L.

1985-01-01

206

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.

207

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

2013-11-21

208

Mammalian Fatty Acid Elongases  

PubMed Central

Summary Very long chain fatty acids confer functional diversity on cells by variations in their chain length and degree of unsaturation. Microsomal fatty acid elongation represents the major pathway for determining the chain length of saturated, monounsaturated, and polyunsaturated fatty acids in cellular lipids. The overall reaction for fatty acid elongation involves four enzymes and utilizes malonyl CoA, NADPH, and fatty acyl CoA as substrates. While the fundamental pathway and its requirements have been known for many years, recent advances have revealed a family of enzymes involved in the first step of the reaction, i.e., the condensation reaction. Seven fatty acid elongase subtypes (Elovl #1–7) have been identified in the mouse, rat, and human genomes. These enzymes determine the rate of overall fatty acid elongation. Moreover, these enzymes also display differential substrate specificity, tissue distribution, and regulation, making them important regulators of cellular lipid composition as well as specific cellular functions. Herein, methods are described to measure elongase activity, analyze elongation products, and alter cellular elongase expression. PMID:19763486

Jump, Donald B.

2009-01-01

209

Reaction of caffeic acid derivatives with acidic nitrite  

Microsoft Academic Search

Caffeic derivatives were reacted with acidic nitrite at controlled pH in order to mimic the gastric juice conditions. At pH 2, whereas caffeic acid reacts exclusively on the side chain, its esters are readily nitrated. Under more acidic conditions (pH 1), caffeic acid methyl ester undergoes a dimerisation into a norlignan derivative.

Philippe Cotelle; Hervé Vezin

2001-01-01

210

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

211

What is Acid Rain? Explore the Acid Lake  

NSDL National Science Digital Library

Acid rain is a type of air pollution that occurs when certain chemicals mix with water in the air. Most chemicals that cause acid rain come from the emissions from factories and cars. Acid rain looks just like 'normal' rain but when it falls, it can hurt plants and animals. For example, when acid rain falls into a lake or river, it makes that body of water more acidic. Many plants and animals cannot live in acidic water. Play this game, from Earth Day Canada's EcoKids program, to learn more about acid rain and its impact on the environment.

Canada, Earth D.

2010-01-01

212

Domoic acid epileptic disease.  

PubMed

Domoic acid epileptic disease is characterized by spontaneous recurrent seizures weeks to months after domoic acid exposure. The potential for this disease was first recognized in a human case study of temporal lobe epilepsy after the 1987 amnesic shellfish-poisoning event in Quebec, and was characterized as a chronic epileptic syndrome in California sea lions through investigation of a series of domoic acid poisoning cases between 1998 and 2006. The sea lion study provided a breadth of insight into clinical presentations, unusual behaviors, brain pathology, and epidemiology. A rat model that replicates key observations of the chronic epileptic syndrome in sea lions has been applied to identify the progression of the epileptic disease state, its relationship to behavioral manifestations, and to define the neural systems involved in these behavioral disorders. Here, we present the concept of domoic acid epileptic disease as a delayed manifestation of domoic acid poisoning and review the state of knowledge for this disease state in affected humans and sea lions. We discuss causative mechanisms and neural underpinnings of disease maturation revealed by the rat model to present the concept for olfactory origin of an epileptic disease; triggered in dendodendritic synapases of the olfactory bulb and maturing in the olfactory cortex. We conclude with updated information on populations at risk, medical diagnosis, treatment, and prognosis. PMID:24663110

Ramsdell, John S; Gulland, Frances M

2014-03-01

213

Electrochemical Determination of Lipoic Acid  

Microsoft Academic Search

Procedures for determining lipoic acid by voltammetry and coulometric titration with electrogenerated halogens using the biamperometric indication of the titration end-point were developed. Possible mechanisms of lipoic acid oxidation with electrogenerated halogens are discussed. Microgram amounts of lipoic acid were determined in model solutions with an RSD of 1–2%. The analytical range of lipoic acid found by voltammetry at a

G. K. Ziyatdinova; G. K. Budnikov; V. I. Pogorel'tsev

2004-01-01

214

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

215

Acid Catalysis in Modern Organic  

E-print Network

Acid Catalysis in Modern Organic Synthesis "Acid is one of the oldest, but the most important follows their earlier book "Lewis Acids in Organic Synthesis (2000)", and covers the new developments of university studies, in which an evil-smelling carbox- ylic acid and an alcohol were converted into a fragrant

Snyder, Scott A.

216

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

217

Nucleophilic reactions of sorbic acid  

Microsoft Academic Search

The conjugated dienoic acid structure of sorbic acid renders it susceptible to nucleophilic attack. Nucleophiles known to react with sorbic acid include sulphite ion and amines. These attack the molecule in position 5 and, in the cse of amines, cyclization to form substituted dihydropyridones may follow. Recent investigations show that thiols in general can also add to sorbic acid. Cysteine,

G. D. Khandelwal; B. L. Wedzicha

1990-01-01

218

DOCOSAHEXAENOIC ACID AND ARACHIDONIC ACID PREVENT ESSENTIAL FATTY ACID DEFICIENCY AND HEPATIC STEATOSIS  

PubMed Central

Objectives Essential fatty acids are important for growth, development, and physiologic function. Alpha-linolenic acid and linoleic acid are the precursors of docosahexaenoic and arachidonic acid, respectively, and have traditionally been considered the essential fatty acids. However, we hypothesized that docosahexaenoic acid and arachidonic acid can function as the essential fatty acids. Methods Using a murine model of essential fatty acid deficiency and consequent hepatic steatosis, we provided mice with varying amounts of docosahexaenoic and arachidonic acids to determine whether exclusive supplementation of docosahexaenoic and arachidonic acids could prevent essential fatty acid deficiency and inhibit or attenuate hepatic steatosis. Results Mice supplemented with docosahexaenoic and arachidonic acids at 2.1% or 4.2% of their calories for 19 days had normal liver histology and no biochemical evidence of essential fatty acid deficiency, which persisted when observed after 9 weeks. Conclusion Supplementation of sufficient amounts of docosahexaenoic and arachidonic acids alone without alpha-linolenic and linoleic acids meets essential fatty acid requirements and prevents hepatic steatosis in a murine model. PMID:22038210

Le, Hau D.; Meisel, Jonathan A.; de Meijer, Vincent E.; Fallon, Erica M.; Gura, Kathleen M.; Nose, Vania; Bistrian, Bruce R.; Puder, Mark

2012-01-01

219

Molecular Structure of Succinic acid  

NSDL National Science Digital Library

Succinic acid is an odorless and colorless crystal, triclinic or monoclinic prism with a very acid taste. Succinic acid is one of the natural acids found in broccoli, rhubarb, beets, asparagus, fresh meat extracts, sauerkraut and cheese. It is also a constituent of almost all plant and animal tissues and plays an important role in intermediary metabolism. Succinic acid is produced commercially by catalytic hydrogenation of maleic or fumaric acid or by acid hydrolysis of succinonitrile. Succinic acid is used in flavoring for food and beverages, and in the manufacture of lacquers, dyes, esters for perfumes, succinates, in photography and in foods as a sequestrant, buffer and neutralizing agent. Succinic acid has uses in certain drug compounds and in agricultural production. An interesting fact, succcinic acid has also been found in meteorites.

2004-11-11

220

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

2013-01-01

221

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

222

Acid rain degradation of nylon  

Microsoft Academic Search

Acid rain, precipitation with a pH less than 5.6, is known to damage lakes, vegetation and buildings. Degradation of outdoor textiles by acid rain is strongly suspected but not well documented. This study reports the effects of sunlight, aqueous acid, heat and humidity (acid rain conditions) on spun delustered nylon 6,6 fabric. Untreated nylon and nylon treated with sulfuric acid

Kyllo

1984-01-01

223

Liposomal spherical nucleic acids.  

PubMed

A novel class of metal-free spherical nucleic acid nanostructures was synthesized from readily available starting components. These particles consist of 30 nm liposomal cores, composed of an FDA-approved 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipid monomer. The surface of the liposomes was functionalized with DNA strands modified with a tocopherol tail that intercalates into the phospholipid layer of the liposomal core via hydrophobic interactions. The spherical nucleic acid architecture not only stabilizes these constructs but also facilitates cellular internalization and gene regulation in SKOV-3 cells. PMID:24983505

Banga, Resham J; Chernyak, Natalia; Narayan, Suguna P; Nguyen, SonBinh T; Mirkin, Chad A

2014-07-16

224

Polyvalent nucleic acid nanostructures.  

PubMed

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 are comprised of only cross-linked 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. PMID:21630678

Cutler, Joshua I; Zhang, Ke; Zheng, Dan; Auyeung, Evelyn; Prigodich, Andrew E; Mirkin, Chad A

2011-06-22

225

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. PMID:21630678

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

2011-01-01

226

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

227

[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

228

Plant fatty acid hydroxylase  

DOEpatents

The present invention relates to the identification of nucleic acid sequences and constructs, and methods related thereto, and the use of these sequences and constructs to produce genetically modified plants for the purpose of altering the composition of plant oils, waxes and related compounds.

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

2000-01-01

229

ACID AEROSOL MEASUREMENT WORKSHOP  

EPA Science Inventory

This report documents the discussion and results of the U.S. EPA Acid Aerosol Measurement Workshop, conducted February 1-3, 1989, in Research Triangle Park, North Carolina. t was held in response to recommendations by the Clean Air Scientific Advisory Committee (CASAC) regarding ...

230

Deoxyribonucleic acid Genetic material  

E-print Network

salt to dissolve them) #12; Precipitate DNA (with ethanol) #12; Species identification VS. #12;Bag#12; Deoxyribonucleic acid Genetic material Chain of molecules linked together DNA contains in Protein Science Published by John Wiley & Sons, Inc. #12; Remove proteins that are bound to DNA (using

Rose, Michael R.

231

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

232

Acid monitoring kit  

US Patent & Trademark Office Database

An acid monitoring kit is provided which is especially useful for monitoring acid rain. The kit includes a base plate having three discrete areas. One area is provided with a plurality of discrete separable bibulous pH indicator strips, each strip being impregnated with a selected acid-base indicator which is visually recognizable as at least one unique color in each such bibulous pH indicator strip when the bibulous strip is dry, and as a different color upon being wetted with water, the different color being dependent on the pH of the water. A second discrete area is provided with a plurality of color comparison reference standards in a plurality of zones, each zone being of a unique color which corresponds to the color of the water-wetted bibulous pH indictor strip, whereby comparison of the unique color of the pH indicator strip with the unique color of the reference standard provides an indication of the pH of the water. A third discrete area is also labelled to provide the requisite information for the use of such acid monitoring kit to correlate the unique color developed in the bibulous pH indicator strip to a unique color of the reference standard to provide an indication of the pH of the water.

1990-10-02

233

Plant fatty acid hydroxylase  

SciTech Connect

The present invention relates to the identification of nucleic acid sequences and constructs, and methods related to the use of these sequences and constructs to produce genetically modified plants for the purpose of altering the composition of plant oils, waxes and related compounds.

Somerville, C.; Loo, F. van de

2000-02-22

234

Alpha Hydroxy Acids  

MedlinePLUS

... skin or mucous membrane, such as the lips, bear a statement that conveys the following information: Sunburn Alert: This product contains an alpha hydroxy acid (AHA) that may increase your skin's sensitivity to the sun and particularly the possibility of sunburn. Use a ...

235

Molecular Structure of Aspartic Acid  

NSDL National Science Digital Library

Aspartate was first isolated in 1868 from legumin in plant seeds. Aspartic acid forms colorless crystals that are soluble in water and insoluble in alcohols and ethers. This is a naturally occurring nonessential amino acid that is produced in the liver from oxaloacetic acid, but is plentiful in meats and sprouting seeds. The amino acid is important in the Krebs cycle as well as the urea cycle, where it is vital in the elimination of dietary waste products. Aspartic acid is required for stamina, brain and neural health. This acid has been found to be important in the functioning of ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and in the production of immunoglobin and antibody synthesis. A deficiency of aspartate will lead to fatigue and depression. Aspartic acid has many uses that include biological and clinical studies, preparation of culture media, and it also functions as a detergent, fungicide, germicide, and metal complexation.

2002-08-20

236

Uric acid inhibits placental system A amino acid uptake.  

PubMed

Hyperuricemia, a common clinical characteristic of preeclamptic pregnancies, has historically been considered a marker of reduced renal function in preeclamptic women. More recently it has been suggested that uric acid may directly contribute to pathological cell signaling events involved in disease progression as well as maternal and fetal pregnancy outcomes including fetal growth restriction. We hypothesize that the increased frequency of restricted fetal growth seen in relation to increasing uric acid concentrations in preeclamptic women is in part the result of uric acid-induced reductions in amino acid transport across the placenta. The objective of the current study was to examine the effects of uric acid on human placental System A amino acid transport using a primary placental villous explant model. Further, we examined the necessity of uric acid uptake and the role of redox signaling as a potential mechanism through which uric acid may attenuate System A activity. Placental uptake of a radiolabeled amino acid analogue, specific to the System A transporter, was reduced in a concentration-dependent fashion with increasing uric acid (0-7 mg/dL), corresponding to uric acid concentrations measured in healthy pregnant and preeclamptic women in the third trimester. Uric acid-induced reduction in System A activity was partially reversed by NADPH oxidase inhibition and completely eliminated by antioxidant treatment. This study demonstrates inhibition of placental System A amino acid transport with uric acid treatment, as a result of uric acid-induced stimulation of intracellular redox signaling cascades. These findings may be relevant to the increased frequency of fetal growth restriction observed in hyperuricemic preeclampsia. Additionally the results of this study, indicating a detrimental effect of hyperuricemia on amino acid transport in the placenta, at concentrations present in women with preeclampsia, also suggest a role for uric acid in the pathophysiology of preeclampsia. PMID:19058847

Bainbridge, S A; von Versen-Höynck, F; Roberts, J M

2009-02-01

237

Uric Acid Inhibits Placental System A Amino Acid Uptake?  

PubMed Central

Hyperuricemia, a common clinical characteristic of preeclamptic pregnancies, has historically been considered a marker of reduced renal function in preeclamptic women. More recently it has been suggested that uric acid may directly contribute to pathological cell signaling events involved in disease progression as well as maternal and fetal pregnancy outcomes including fetal growth restriction. We hypothesize that the increased frequency of restricted fetal growth seen in relation to increasing uric acid concentrations in preeclamptic women is in part the result of uric acid-induced reductions in amino acid transport across the placenta. The objective of the current study was to examine the effects of uric acid on human placental System A amino acid transport using a primary placental villous explant model. Further, we examined the necessity of uric acid uptake and the role of redox signaling as a potential mechanism through which uric acid may attenuate System A activity. Placental uptake of a radiolabeled amino acid analogue, specific to the System A transporter, was reduced in a concentration-dependent fashion with increasing uric acid (0?7 mg/dL), corresponding to uric acid concentrations measured in healthy pregnant and preeclamptic women in the third trimester. Uric acid-induced reduction in System A activity was partially reversed by NADPH oxidase inhibition and completely eliminated by antioxidant treatment. This study demonstrates inhibition of placental System A amino acid transport with uric acid treatment, as a result of uric acid-induced stimulation of intracellular redox signaling cascades. These findings may be relevant to the increased frequency of fetal growth restriction observed in hyperuricemic preeclampsia. Additionally the results of this study, indicating a detrimental effect of hyperuricemia on amino acid transport in the placenta, at concentrations present in women with preeclampsia, also suggest a role for uric acid in the pathophysiology of preeclampsia. PMID:19058847

Bainbridge, S.A.; von Versen-Hoynck, F.; Roberts, J.M.

2009-01-01

238

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. PMID:22531947

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

239

Fatty acid-producing hosts  

SciTech Connect

Described are hosts for overproducing a fatty acid product such as a fatty acid. The hosts include an exogenous nucleic acid encoding a thioesterase and, optionally, an exogenous nucleic acid encoding an acetyl-CoA carboxylase, wherein an acyl-CoA synthetase in the hosts are functionally delected. The hosts prefereably include the nucleic acid encoding the thioesterase at an intermediate copy number. The hosts are preferably recominantly stable and growth-competent at 37.degree. C. Methods of producing a fatty acid product comprising culturing such hosts at 37.degree. C. are also described.

Pfleger, Brian F; Lennen, Rebecca M

2013-12-31

240

Acidizing of Sandstone Reservoirs Using HF and Organic Acids  

E-print Network

Mud acid, which is composed of HCl and HF, is commonly used to remove the formation damage in sandstone reservoirs. However, many problems are associated with HCl, especially at high temperatures. Formic-HF acids have served as an alternative...

Yang, Fei

2012-10-19

241

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

242

Preterm infant formula supplementation with ? linolenic acid and docosahexaenoic acid  

Microsoft Academic Search

Objectives: To investigate if supplementation of preterm infant formula with a high docosahexaenoic acid\\/eicosapentaenoic acid (DHA\\/EPA) ratio together with ?-linolenic acid (ALA) was able to maintain plasma and red blood cell DHA levels similar to that obtained with breast milk feeding without altering n-6 fatty acid status.Design and subjects: Preterm infants of mothers who elected not to breast feed (n=13)

A Rodriguez; D Raederstorff; P Sarda; C Lauret; F Mendy; B Descomps

2003-01-01

243

Carboxylic Acid Unknowns and Titration 90 CARBOXYLIC ACID UNKNOWN  

E-print Network

Carboxylic Acid Unknowns and Titration 90 CARBOXYLIC ACID UNKNOWN A. Solubility Tests: Water, NaHCO3, and NaOH Test the solubility of your acid first in neutral water, in NaOH/H2O, and in NaHCO3 to 30 drops. Swirl/mix well. Use of small stir bar helps. · Water Test: Only acids with small numbers

Jasperse, Craig P.

244

Boswellic acid inhibits expression of acid sphingomyelinase in intestinal cells  

PubMed Central

Background Boswellic acid is a type of triterpenoids with antiinflammatory and antiproliferative properties. Sphingomyelin metabolism generates multiple lipid signals affecting cell proliferation, inflammation, and apoptosis. Upregulation of acid sphingomyelinase (SMase) has been found in several inflammation-related diseases such as inflammatory bowel diseases, atherosclerosis, and diabetes. Methods The present study is to examine the effect of 3-acetyl-11-keto-?-boswellic acids (AKBA), a potent boswellic acid, on acid SMase activity and expression in intestinal cells. Both transformed Caco-2 cells and non-transformed Int407 cells were incubated with AKBA. After incubation, the change of acid SMase activity was assayed biochemically, the enzyme protein was examined by Western blot, and acid SMase mRNA was quantified by qPCR. Results We found that AKBA decreased acid SMase activity in both intestinal cell lines in dose and time dependent manners without affecting the secretion of the enzyme to the cell culture medium. The effect of AKBA was more effective in the fetal bovine serum-free culture medium. Among different types of boswellic acid, AKBA was the most potent one. The inhibitory effect on acid SMase activity occurred only in the intact cells but not in cell-free extract in the test tubes. At low concentration, AKBA only decreased the acid SMase activity but not the quantity of the enzyme protein. However, at high concentration, AKBA decreased both the mass of acid SMase protein and the mRNA levels of acid SMase in the cells, as demonstrated by Western blot and qPCR, respectively. Under the concentrations decreasing acid SMase activity, AKBA significantly inhibited cell proliferation. Conclusion We identified a novel inhibitory effect of boswellic acids on acid SMase expression, which may have implications in human diseases and health. PMID:19951413

2009-01-01

245

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

246

Focus Sheet | Hydrofluoric Acid Health hazards of hydrofluoric acid  

E-print Network

characterized by weight loss, brittle bones, anemia, and general ill health. Safe use If possible, avoid workingFocus Sheet | Hydrofluoric Acid Health hazards of hydrofluoric acid Hydrofluoric acid (HF bone. Skin exposure to highly concentrated HF (48% or greater) immediately results in serious

Wilcock, William

247

Acid placement and coverage in the acid jetting process  

E-print Network

Many open-hole acid treatments are being conducted by pumping acid through jetting ports placed at the end of coiled tubing or drill pipe. The filter-cake on the bore-hole is broken by the jet; the acid-soluble material is dissolved, creating...

Mikhailov, Miroslav I.

2009-05-15

248

Autohydrolysis of phytic acid.  

PubMed

The autohydrolysis of phytic acid at 120 degrees C resulted in the formation of most of the phosphate esters of myo-inositol in varying amounts depending upon the reaction time. Eighteen of the 39 chromatographically distinct myo-inositol mono-, bis-, tris-, tetrakis-, pentakis-, and hexakisphosphates have been characterized using two different HPLC systems. These myo-inositol phosphates were partially purified by preparative anion-exchange chromatography under acidic and alkaline elution conditions. The combination of these two methods provides a two-tiered chromatographic approach to the rapid and sensitive identification of inositol phosphates in complex mixtures. Identification of the products was confirmed by 1D and 2D (1)H NMR analysis. The analytical procedure was applied to the autohydrolysis of the mixture of inositol phosphates from corn steep water. PMID:10469496

Hull, S R; Gray, J S; Montgomery, R

1999-09-10

249

Acid hydrolysis of cellulose  

SciTech Connect

One of the alternatives to increase world production of etha nol is by the hydrolysis of cellulose content of agricultural residues. Studies have been made on the types of hydrolysis: enzimatic and acid. Data obtained from the sulphuric acid hydrolysis of cellulose showed that this process proceed in two steps, with a yield of approximately 95% glucose. Because of increases in cost of alternatives resources, the high demand of the product and the more economic production of ethanol from cellulose materials, it is certain that this technology will be implemented in the future. At the same time further studies on the disposal and reuse of the by-products of this production must be undertaken.

Salazar, H.

1980-12-01

250

(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

251

The utilization of tricarboxylic acid cycle acids and the uptake of succinic acid by Neurospora crassa  

E-print Network

, Clavice s u urea and several species of ~dtlt . 1' ~ d 9' p ~ d t 1966 (69) th t ~C. PRL 1980 was able to grow with succinic acid as the sole carbon source in an acidic medium. The efficiency of total biomass synthesis on succinic acid was considerably..., Clavice s u urea and several species of ~dtlt . 1' ~ d 9' p ~ d t 1966 (69) th t ~C. PRL 1980 was able to grow with succinic acid as the sole carbon source in an acidic medium. The efficiency of total biomass synthesis on succinic acid was considerably...

Gilliland, Patti Lynn

2012-06-07

252

Molecular Structure of Sulfuric Acid  

NSDL National Science Digital Library

H2SO4 was discovered by alchemists and made from heating a compound of iron sulfate. In 1740, sulfuric acid was produced for commercial sale. Sulfuric acid is a very strong acid which is used in car batteries. The acid disassociates in water to give two protons and sulfate. This acid can destroy flesh and cause blindness. It was discovered in the 19th century that adding sulfuric acid to soil produces phosphorus, which is beneficial to plants; hence, sulfuric acid is used as a fertilizer in the form of super phosphate and ammonium sulfate. Sulfuric acid is also used to refine petroleum and process metals, and is found in paints and car batteries.

2002-08-15

253

Molecular Structure of Maleic acid  

NSDL National Science Digital Library

Maleic acid is colorless to white crystals with a faint acidulous odor and a characteristic repulsive, astringent taste. Maleic acid is used in making polyesters, surface coatings, lubricant additives, agricultural chemicals and paint vehicles. It is used in organic synthesis of fumaric acid, succinic, aspartic, tartaric, propionic, lactic, malonic, acrylic and hydrocarylic acids. Maleic acid and its anhydride are prepared industrially by the catalytic oxidation of benzene. Maleic acid may be released into waste water during its production and used in the manufacture of polymer products. Dust of maleic acid is irritating to the eyes, nose and throat. The general population is exposed to maleic acid in areas with heavy traffic since it is found in aerosols from auto exhaust.

2004-11-10

254

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

255

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

256

Acid hydrolysis of chitosans  

Microsoft Academic Search

The hydrolysis of the O-glycosidic linkages (depolymerization) and the N-acetyl linkage (de-N-acetylation) of partially N-acetylated chitosans were studied in dilute and concentrated HCl. The rate of hydrolysis of the glycosidic linkages was found to be equal to the rate of de-N-acetylation in dilute acid, while the glycosidic linkages was hydrolysed more than 10 times faster than the N-acetyl linkage in

K. M. Vårum; M. H. Ottøy; O. Smidsrød

2001-01-01

257

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

258

Lipoic acid biosynthesis defects.  

PubMed

Lipoate is a covalently bound cofactor essential for five redox reactions in humans: in four 2-oxoacid dehydrogenases and the glycine cleavage system (GCS). Two enzymes are from the energy metabolism, ?-ketoglutarate dehydrogenase and pyruvate dehydrogenase; and three are from the amino acid metabolism, branched-chain ketoacid dehydrogenase, 2-oxoadipate dehydrogenase, and the GCS. All these enzymes consist of multiple subunits and share a similar architecture. Lipoate synthesis in mitochondria involves mitochondrial fatty acid synthesis up to octanoyl-acyl-carrier protein; and three lipoate-specific steps, including octanoic acid transfer to glycine cleavage H protein by lipoyl(octanoyl) transferase 2 (putative) (LIPT2), lipoate synthesis by lipoic acid synthetase (LIAS), and lipoate transfer by lipoyltransferase 1 (LIPT1), which is necessary to lipoylate the E2 subunits of the 2-oxoacid dehydrogenases. The reduced form dihydrolipoate is reactivated by dihydrolipoyl dehydrogenase (DLD). Mutations in LIAS have been identified that result in a variant form of nonketotic hyperglycinemia with early-onset convulsions combined with a defect in mitochondrial energy metabolism with encephalopathy and cardiomyopathy. LIPT1 deficiency spares the GCS, and resulted in a combined 2-oxoacid dehydrogenase deficiency and early death in one patient and in a less severely affected individual with a Leigh-like phenotype. As LIAS is an iron-sulphur-cluster-dependent enzyme, a number of recently identified defects in mitochondrial iron-sulphur cluster synthesis, including NFU1, BOLA3, IBA57, GLRX5 presented with deficiency of LIAS and a LIAS-like phenotype. As in DLD deficiency, a broader clinical spectrum can be anticipated for lipoate synthesis defects depending on which of the affected enzymes is most rate limiting. PMID:24777537

Mayr, Johannes A; Feichtinger, René G; Tort, Frederic; Ribes, Antonia; Sperl, Wolfgang

2014-07-01

259

Acid Deposition Sampling  

NSDL National Science Digital Library

This learning activity from the Advanced Technology Environmental and Energy Center (ATEEC) provides students with the opportunity to use analytical meters and instruments and perform acid deposition sampling. Students will collect samples from various sources over a period of time, then measure pH and develop graphs or charts. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.

Willey, Babe

2011-02-17

260

Modulation of membrane curvature by phosphatidic acid and lysophosphatidic acid.  

PubMed

The local generation of phosphatidic acid plays a key role in the regulation of intracellular membrane transport through mechanisms which are largely unknown. Phosphatidic acid may recruit and activate downstream effectors, or change the biophysical properties of the membrane and directly induce membrane bending and/or destabilization. To evaluate these possibilities, we determined the phase properties of phosphatidic acid and lysophosphatidic acid at physiological conditions of pH and ion concentrations. In single-lipid systems, unsaturated phosphatidic acid behaved as a cylindrical, bilayer-preferring lipid at cytosolic conditions (37 degrees C, pH 7.2, 0.5 mM free Mg2+), but acquired a type-II shape at typical intra-Golgi conditions, a mildly acidic pH and submillimolar free Ca2+ (pH 6.6-5.9, 0.3 mM Ca2+). Lysophosphatidic acid formed type-I lipid micelles in the absence of divalent cations, but anhydrous cation-lysophosphatidic acid bilayer complexes in their presence. These data suggest a similar molecular shape for phosphatidic acid and lysophosphatidic acid at cytosolic conditions; however, experiments in mixed-lipid systems indicate that their shape is not identical. Lysophosphatidic acid stabilized the bilayer phase of unsaturated phosphatidylethanolamine, while the opposite effect was observed in the presence of phosphatidic acid. These results support the hypothesis that a conversion of lysophosphatidic acid into phosphatidic acid by endophilin or BARS (50 kDa brefeldin A ribosylated substrate) may induce negative spontaneous monolayer curvature and regulate endocytic and Golgi membrane fission. Alternative models for the regulation of membrane fission based on the strong dependence of the molecular shape of (lyso)phosphatidic acid on pH and divalent cations are also discussed. PMID:12656989

Kooijman, Edgar E; Chupin, Vladimir; de Kruijff, Ben; Burger, Koert N J

2003-03-01

261

Exposures to acidic aerosols  

SciTech Connect

Ambient monitoring of acid aerosols in four U.S. cities and in a rural region of southern Ontario clearly show distinct periods of strong acidity. Measurements made in Kingston, TN, and Steubenville, OH, resulted in 24-hr H+ ion concentrations exceeding 100 nmole/m/sup 3/ more than 10 times during summer months. Periods of elevated acidic aerosols occur less frequently in winter months. The H+ determined during episodic conditions in southern Ontario indicates that respiratory tract deposition can exceed the effects level reported in clinical studies. Observed 12-hr H+ concentrations exceeded 550 nmole/m/sup 3/ (approximately 27 micrograms/m/sup 3/ H/sub 2/SO/sub 4/). The maximum estimated 1-hr concentration exceeded 1500 nmole/m/sup 3/ for H+ ions. At these concentrations, an active child might receive more than 2000 nmole of H+ ion in 12 hr and in excess of 900 nmole during the hour when H/sub 2/SO/sub 4/ exceeded 50 micrograms/m/sup 3/.

Spengler, J.D.; Keeler, G.J.; Koutrakis, P.; Ryan, P.B.; Raizenne, M.; Franklin, C.A.

1989-02-01

262

Exposures to acidic aerosols  

SciTech Connect

Ambient monitoring of acid aerosols in four U.S. cities and in a rural region of southern Ontario clearly show distinct periods of strong acidity. Measurements made in Kingston, TN, and Steubenville, OH, resulted in 24-hr H(+) ion concentrations exceeding 100 nmole/cu m more than 10 times during summer months. Periods of elevated acidic aerosols occur less frequently in winter months. The H(+) determined during episodic conditions in southern Ontario indicates that respiratory tract deposition can exceed the effects level reported in clinical studies. Observed 12-hr (H+) concentrations exceeded 550 nmole/cu m (approximately 27 microgram/cu m H{sub 2}SO{sub 4}). The maximum estimated 1-hr concentration exceeded 1500 nmole/cu m for H(+) ions. At these concentrations, an active child might receive more than 2000 nmole of H(+) ion in 12 hr and in excess of 900 nmole during the hour when H{sub 2}SO{sub 4} exceeded 50 microgram/cu m.

Spengler, J.D.; Keeler, G.J.; Koutrakis, P.; Ryan, P.B.; Raizenne, M.

1989-01-01

263

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.

264

Microbial naphthenic Acid degradation.  

PubMed

Naphthenic acids (NAs) are an important group of trace organic pollutants predominantly comprising saturated aliphatic and alicyclic carboxylic acids. NAs are ubiquitous; occurring naturally in hydrocarbon deposits (petroleum, oil sands, bitumen, and crude oils) and also have widespread industrial uses. Consequently, NAs can enter the environment from both natural and anthropogenic processes. NAs are highly toxic, recalcitrant compounds that persist in the environment for many years, and it is important to develop efficient bioremediation strategies to decrease both their abundance and toxicity in the environment. However, the diversity of microbial communities involved in NA-degradation, and the mechanisms by which NAs are biodegraded, are poorly understood. This lack of knowledge is mainly due to the difficulties in identifying and purifying individual carboxylic acid compounds from complex NA mixtures found in the environment, for microbial biodegradation studies. This paper will present an overview of NAs, their origin and fate in the environment, and their toxicity to the biota. The review describes the microbial degradation of both naturally occurring and chemically synthesized NAs. Proposed pathways for aerobic NA biodegradation, factors affecting NA biodegradation rates, and possible bioremediation strategies are also discussed. PMID:20359455

Whitby, Corinne

2010-01-01

265

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

266

Enviropedia: Introduction to Acid Rain  

NSDL National Science Digital Library

This resource provides information about acid rain, a widespread term used to describe all forms of acid precipitation. The sources, nature, and chemistry of acid rain are discussed, along with its impact on buildings, soils, freshwater lakes, trees, and wildlife. Other topics include measuring, modeling, and monitoring acid rain; and vehicle and industrial emission controls. The problem of airborne pollutants migrating across international borders is also discussed.

267

Antioxidant properties of nitrocaffeic acids  

Microsoft Academic Search

A series of nitrodihydroxybenzenes and nitrocaffeic acids were prepared and their hydroxyl radical (OH°) and superoxide anion (O2?) scavenging activities and xanthine oxidase inhibition activities were evaluated. 2-Nitrocaffeic acid is the more potent O2? scavenger. 2- (and 5)-Nitrocaffeic acids are the more potent xanthine oxidase inhibitors.

Jean-Luc Grenier; Nicole Cotelle; Philippe Cotelle; Jean-Pierre Catteau

1996-01-01

268

Acid rain and dry deposition  

Microsoft Academic Search

This book provides information on the formation of acid rain and the long-range transport of air pollutants. The effects of acid precipitation on both terrestrial and aquatic ecosystems are highlighted and technical and policy issues associated with the delineation and implementation of control strategies for acid rain and dry deposition are covered. Dry deposition is addressed, with emphasis given to

Canter

1985-01-01

269

Acid rain: the international response  

Microsoft Academic Search

Acid rain or technically “acid deposition” has far reaching environmental, economic, political and international implications. It has been blamed for large?scale damage to aquatic ecosystems and forests in Scandinavia, southeastern Canada and the northeastern United States. A number of other countries have expressed concern about the possible affects of acid rain on water bodies, forests, agricultural crops and material structures.Never

Gordon L. Brady; Joseph C. Selle

1985-01-01

270

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

271

Do We Need Gastric Acid?  

Microsoft Academic Search

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;

D. Pohl; M. Fox; M. Fried; B. Göke; C. Prinz; H. Mönnikes; G. Rogler; M. Dauer; J. Keller; F. Lippl; I. Schiefke; U. Seidler; H. D. Allescher

2008-01-01

272

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. 10 figs.

King, C.J.; Poole, L.J.

1995-05-02

273

Human thyroid autoantigens and proteins of Yersinia and Borrelia share amino acid sequence homology that includes binding motifs to HLA-DR molecules and T-cell receptor.  

PubMed

We previously reported that the spirochete Borrelia burgdorferi could trigger autoimmune thyroid diseases (AITD). Subsequently, we showed local amino acid sequence homology between all human thyroid autoantigens (human thyrotropin receptor [hTSH-R], human thyroglobulin [hTg], human thyroperoxidase [hTPO], human sodium iodide symporter [hNIS]) and Borrelia proteins (n = 6,606), and between hTSH-R and Yersinia enterocolitica (n = 1,153). We have now updated our search of homology with Borrelia (n = 11,198 proteins) and extended our search on Yersinia to the entire species (n = 40,964 proteins). We also searched the homologous human and microbial sequences for peptide-binding motifs of HLA-DR molecules, because a number of these class II major histocompatibility complex (MHC) molecules (DR3, DR4, DR5, DR8, and DR9) are associated with AITD. Significant homologies were found for only 16 Borrelia proteins (5 with hTSH-R, 2 with hTg, 3 with hTPO, and 6 with hNIS) and only 19 Yersinia proteins (4 with hTSH-R, 2 with hTg, 2 with hTPO, and 11 with hNIS). Noteworthy, segments of thyroid autoantigens homologous to these microbial proteins are known to be autoantigenic. Also, the hTSH-R homologous region of one Borrelia protein (OspA) contains an immunodominant epitope that others have found to be homologous to hLFA-1. This is of interest, as the hLFA-1/ICAM-1 ligand/receptor pair is aberrantly expressed in the follicular cells of thyroids affected by Hashimoto's thyroiditis. A computer-assisted search detected antigenic peptide binding motifs to the DR molecules implicated in AITD. In conclusion, our in silico data do not directly demonstrate that Borrelia and Yersinia proteins trigger AITD but suggest that a restricted number of them might have the potential to, at least in persons with certain HLA-DR alleles. PMID:16571084

Benvenga, Salvatore; Santarpia, Libero; Trimarchi, Francesco; Guarneri, Fabrizio

2006-03-01

274

Determination of the solubility products of nitrilotriacetic acid, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid  

Microsoft Academic Search

A method is described for the determination of solubility products for polyaminopolycarboxylic acids. The neutral protonated species of NTA (nitrilotriacetic acid), EDTA (ethylenediaminetetraacetic acid) and DTPA (diethylenetriaminepentaacetic acid) were precipitated at low pH values. The amount of precipitate was quantified by gravimetry and complexometric titrations with a standard zinc(II) solution. The following solubility products were obtained: SH3NTA=10?16.36, SH4EDTA=10?24.66 and SH5DTPA=10?30.43.

Jouni Karhu; Leo Harju; Ari Ivaska

1999-01-01

275

Solvent extraction of inorganic acids  

E-print Network

and solubility of nitric acid and sulfuric acid with organic solvents have been published Olander, Donadieu, and Benedict (12) studied the 'istributlon of nitric acid between water and tributyl phosphate-hexane solvent nd dcharf and Gean. . oplis (1...(. ) reported on the system nit ic acid-water-n-butyl alcohols Distribution of sulfuric acid was m-de oy Bchlea and Gean- koplis (19) with n-butyl alcohol, by Gibby ( 7) with nitro- benzene and by Peakin (14) with pyri 'in~. Baldwin, Biggies an" Soldano (2...

Ysrael, Miguel Curie

2012-06-07

276

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

277

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

278

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 to 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 volcanics.

Scalabrin, E.; Zangrando, R.; Barbaro, E.; Kehrwald, N. M.; Gabrieli, J.; Barbante, C.; Gambaro, A.

2012-07-01

279

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

280

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

281

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

282

Corals on Acid  

NSDL National Science Digital Library

The objective of this inquiry-based lesson is for learners to gain an understanding of how increasing ocean acidity can affect the calcification of marine organisms. During this activity, learners: (1) design an experiment to quantify the CaCO3 concentration of two invertebrate skeletal samples, one that has been soaked in normal seawater and another in a low pH solution, and (2) use critical thinking and discussion to evaluate possible explanations for the difference in the skeletal CaCO3 compositions. This lesson plan includes a post-activity demonstration, which shows how the dissolution of CO2 into the ocean lowers pH.

Boleman, Casey L.; Gravinese, Philip M.; Muse, Ellen N.; Marston, Andrea E.; Windsor, John G.

2013-01-01

283

Microbial hyaluronic acid production.  

PubMed

Hyaluronic acid (HA) is a commercially valuable medical biopolymer increasingly produced through microbial fermentation. Viscosity limits product yield and the focus of research and development has been on improving the key quality parameters, purity and molecular weight. Traditional strain and process optimisation has yielded significant improvements, but appears to have reached a limit. Metabolic engineering is providing new opportunities and HA produced in a heterologous host is about to enter the market. In order to realise the full potential of metabolic engineering, however, greater understanding of the mechanisms underlying chain termination is required. PMID:15599518

Chong, Barrie Fong; Blank, Lars M; Mclaughlin, Richard; Nielsen, Lars K

2005-01-01

284

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

285

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

286

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'-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.

Smith, Cassandra L. (Boston, MA); Yaar, Ron (Brookline, MA); Szafranski, Przemyslaw (Boston, MA); Cantor, Charles R. (Boston, MA)

1998-05-19

287

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

288

Growth of nitric acid hydrates on thin sulfuric acid films  

NASA Technical Reports Server (NTRS)

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 x 10(exp -4) Torr H2O and 1-2.5 x 10(exp -6) Torr HNO3) and subjected to cooling and heating cycles. Fourier Transform Infrared (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.

1994-01-01

289

Sedimentation of sulfuric acid in acid tars from current production  

Microsoft Academic Search

Acid tars obtained in treating T-750, KhF-12, and I-8A oils were investigated for purposes of recovering sulfuric acid and asphalt binders from the compositions and of determining the effects of storage time on the recovery. The consumption and sedimentation levels of sulfuric acid during storage for different periods and at different temperatures were assessed. The characteristics of an asphalt binder

T. L. Denisova; A. F. Frolov; A. N. Aminov; S. P. Novosel'tsev

1987-01-01

290

[Modification of hyaluronic acid with aromatic amino acids].  

PubMed

Hyaluronic acid was modified with aromatic amino acids (5-aminosalicylic, 4-aminosalicylic, anthranilic, and p-aminobenzoic) in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. The modified glycans contained 9-43% of arylamide groups and 10-33% of isoureidocarbonyl groups depending on the nature of the amino acid. Reduction with sodium borohydride allowed the conversion of isoureidocarbonyl groups into hydroxymethyl groups. PMID:15787219

Ponedel'kina, I Iu; Odinokov, V N; Vakhrusheva, E S; Golikova, M T; Khalilov, L M; Dzhemilov, U M

2005-01-01

291

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

292

Molecular Structure of Butyric acid  

NSDL National Science Digital Library

n-Butyric acid is a substance that was isolated from butter in 1869. Butyric acid means, in Latin, the acid of butter as it was first discovered in rancid butter. It is found most commonly in butter, but can also be present in some fruits. Butyric acid is also produced synthetically, through fermentation of various carbohydrates, to be used as a flavoring agent in various food products. Applications of butyric acid are as an additive to food, flavorings, varnishes, perfumes, pharmaceuticals and disinfectants. It is also used for the production of plastics, plasticizers, surfactants and textile auxiliaries. Butyric acid and its derivatives are also being seriously considered around the world as potential anticancer agents.

2002-10-11

293

Shaping up nucleic acid computation  

PubMed Central

Summary of recent advances (abstract) Nucleic acid-based nanotechnology has always been perceived as novel, but has begun to move from theoretical demonstrations to practical applications. In particular, the large address spaces available to nucleic acids can be exploited to encode algorithms and/or act as circuits, and thereby process molecular information. In this review we revisit several milestones in the field of nucleic acid-based computation, but also highlight how the prospects for nucleic acid computation go beyond just a large address space. Functional nucleic acid elements (aptamers, ribozymes, and deoxyribozymes) can serve as inputs and outputs to the environment, and can act as logical elements. Into the future, the chemical dynamics of nucleic acids may prove as useful as hybridization for computation. PMID:20538451

Chen, Xi

2010-01-01

294

Molecular Structure of Salicylic acid  

NSDL National Science Digital Library

Salicylic acid is a colorless to white crystalline powder with a sweetish acrid taste that occurs naturally in many microorganisms and plants in very small amounts. It is also made synthetically and used as preservative of food products in some countries and as an antiseptic in mouthwashes and toothpastes. This chemical is also used in the manufacture of methyl salicylates, acetylasalicylic acid (aspirin) and other salicylates. Salicylic acid is a chemical intermediate in the synthesis of dyestuff, salicylate esters and salts. It is prepared commercially by heating sodium phenolate (the sodium salt of phenol) with carbon dioxide under pressure to form sodium salicylate, which is treated with sulfuric acid to liberate salicylic acid. Salicylic acid is quite irritating to skin and mucosa and it destroys epithelial cells. Absorption of large amounts can cause vomiting, abdominal pain, acidosis and mental disturbances.

2004-11-11

295

Clinical use of acid steatocrit.  

PubMed

Malabsorption of fat is an important gastrointestinal cause of malnutrition and growth retardation in childhood. The gold standard for the evaluation of fat malabsorption is the faecal fat balance method. The acid steatocrit method has recently been introduced as a simple method to evaluate faecal fat. The present study was aimed at evaluating the acid steatocrit in clinical practice. Faecal fat excretion and acid steatocrit results were determined in 42 children, half with and half without fat malabsorption. Acid steatocrit results correlated significantly with both faecal fat excretion (p < 0.01) and faecal fat concentration (p < 0.001). Sensitivity and specificity of the acid steatocrit for the diagnosis of malabsorption were 90% and 100%, respectively. We consider the acid steatocrit method useful for the screening and monitoring of patients with steatorrhoea. PMID:9183483

Van den Neucker, A; Pestel, N; Tran, T M; Forget, P P; Veeze, H J; Bouquet, J; Sinaasappel, M

1997-05-01

296

Production of polymalic acid and malic acid by Aureobasidium pullulans fermentation and acid hydrolysis.  

PubMed

Malic acid is a dicarboxylic acid widely used in the food industry and also a potential C4 platform chemical that can be produced from biomass. However, microbial fermentation for direct malic acid production is limited by low product yield, titer, and productivity due to end-product inhibition. In this work, a novel process for malic acid production from polymalic acid (PMA) fermentation followed by acid hydrolysis was developed. First, a PMA-producing Aureobasidium pullulans strain ZX-10 was screened and isolated. This microbe produced PMA as the major fermentation product at a high-titer equivalent to 87.6?g/L of malic acid and high-productivity of 0.61?g/L?h in free-cell fermentation in a stirred-tank bioreactor. Fed-batch fermentations with cells immobilized in a fibrous-bed bioreactor (FBB) achieved the highest product titer of 144.2?g/L and productivity of 0.74?g/L?h. The fermentation produced PMA was purified by adsorption with IRA-900 anion-exchange resins, achieving a ?100% purity and a high recovery rate of 84%. Pure malic acid was then produced from PMA by hydrolysis with 2?M sulfuric acid at 85°C, which followed the first-order reaction kinetics. This process provides an efficient and economical way for PMA and malic acid production, and is promising for industrial application. PMID:23436475

Zou, Xiang; Zhou, Yipin; Yang, Shang-Tian

2013-08-01

297

Racemization of Meteoritic Amino Acids  

Microsoft Academic Search

Meteorites may have contributed amino acids to the prebiotic Earth, affecting the global ratio of right-handed to left-handed (D\\/L) molecules. We calculate D\\/L ratios for seven biological, alpha-hydrogen, protein amino acids over a variety of plausible parent body thermal histories, based on meteorite evidence and asteroid modeling. We show that amino acids in meteorites do not necessarily undergo complete racemization

Barbara A. Cohen; Christopher F. Chyba

2000-01-01

298

Certain derivatives of aminomethylphosphonic acid  

Microsoft Academic Search

Summary 1.Experiments on the acylatlon of aminomethylphosphonic acid show that it proceeds with greater difficulty than the acylation of glycine. Acetamidomethyl-, (chloroacetamido)methyl-, and phthalimidamethyl-phosphonic acids have been prepared.2.The methylation of aminomethylphosphonic acid has been effected by means of methyl iodide in a methanol mediums, and it has been shown that a quaternary iodide derived from the phosphonobetaine is formed. It

Me Io Kabachnik; T. Ya. Medved

1953-01-01

299

Polyaminopolycarboxylic Acids derived from Polyethyleneamines  

Microsoft Academic Search

THE effects of increasing length of the alkylene bridge on acid dissociation constants and metal chelate stability constants of homologues of ethylene-diaminetetra-acetic acid derived from polymethylene-diamines have been reported within recent years1. The effects of an increase in the polydentate and polyelectrolyte nature of polyaminopolycarboxylic acids derived from polyethylene polyamines have not been investigated except for a brief report on

Albert E. Frost

1956-01-01

300

All-trans retinoic acid regulates hepatic bile acid homeostasis.  

PubMed

Retinoic acid (RA) and bile acids share common roles in regulating lipid homeostasis and insulin sensitivity. In addition, the receptor for RA (retinoid x receptor) is a permissive partner of the receptor for bile acids, farnesoid x receptor (FXR/NR1H4). Thus, RA can activate the FXR-mediated pathway as well. The current study was designed to understand the effect of all-trans RA on bile acid homeostasis. Mice were fed an all-trans RA-supplemented diet and the expression of 46 genes that participate in regulating bile acid homeostasis was studied. The data showed that all-trans RA has a profound effect in regulating genes involved in synthesis and transport of bile acids. All-trans RA treatment reduced the gene expression levels of Cyp7a1, Cyp8b1, and Akr1d1, which are involved in bile acid synthesis. All-trans RA also decreased the hepatic mRNA levels of Lrh-1 (Nr5a2) and Hnf4? (Nr2a1), which positively regulate the gene expression of Cyp7a1 and Cyp8b1. Moreover, all-trans RA induced the gene expression levels of negative regulators of bile acid synthesis including hepatic Fgfr4, Fxr, and Shp (Nr0b2) as well as ileal Fgf15. All-trans RA also decreased the expression of Abcb11 and Slc51b, which have a role in bile acid transport. Consistently, all-trans RA reduced hepatic bile acid levels and the ratio of CA/CDCA, as demonstrated by liquid chromatography-mass spectrometry. The data suggest that all-trans RA-induced SHP may contribute to the inhibition of CYP7A1 and CYP8B1, which in turn reduces bile acid synthesis and affects lipid absorption in the gastrointestinal tract. PMID:25175738

Yang, Fan; He, Yuqi; Liu, Hui-Xin; Tsuei, Jessica; Jiang, Xiaoyue; Yang, Li; Wang, Zheng-Tao; Wan, Yu-Jui Yvonne

2014-10-15

301

Organic Acid Production by Basidiomycetes  

PubMed Central

Sixty-seven strains belonging to 47 species of Basidiomycetes were examined for their acid-producing abilities in glucose media, in both the presence and absence of CaCO3, in stationary and shake cultures. Some strains were found to produce large quantities of oxalic acid. The oxalic acid-producing strains could be separated into two groups. Strains of one group (mostly brown-rot fungi) were able to produce oxalic acid, regardless of whether CaCO3 was present in the medium. Strains of the other group (mostly white-rot fungi) were characterized by their ability to produce oxalic acid only when CaCO3 was added to the medium. With the latter group, shake-culturing was generally more effective than stationary culturing in respect to acid production. In the CaCO3-containing media, Schizophyllum commune, Merulius tremellosus, and Porodisculus pendulus were found to produce substantial amounts of L-malic acid as a main metabolic product, along with small quantities of oxalic and other acids in shake cultures. Especially, S. commune and M. tremellosus may be employed as malic acid-producing species. PMID:5867653

Takao, Shoichi

1965-01-01

302

[Ulcer therapy without acid inhibition].  

PubMed

The mechanism of action of ulcer drugs without acid inhibition appears to involve improvement of defensive factors of the gastroduodenal mucosa. The concept of ulcer healing without acid inhibition is attractive for theoretical reasons, because doubts have arisen about the safety of elevation of intragastric pH, especially in long-term treatment of peptic ulcer disease. Ulcer drugs that do not affect gastric acidity may therefore be preferred, provided they compare favorably to the best acid inhibitors available in terms of efficacy, adverse effects and other requirements. Among these drugs, sucralfate fulfills these criteria to a large extent. PMID:6547542

Koelz, H R

1984-05-19

303

Molecular Structure of Lauric acid  

NSDL National Science Digital Library

Lauric acid was first discovered in lauraceae seeds by Marsson T in 1849. The highest content of lauric acid is found in a mother's breast milk and lauraceae seeds. It is used in foods such as vegetable shortenings as a defoaming agent and industrially as a booster for soaps and detergents. Also it is used in cosmetics, insecticides, and food additives. Additionally, Lauric acid is a medium chain fatty acid, which forms monolaurin in the human or animal body. This compound is an antiviral, antibacterial, and antiprotozoal monoglyceride that destroys lipid coated viruses such as HIV, herpes, cytomegalovirus, and influenza.

2002-10-11

304

Acidic gas capture by diamines  

DOEpatents

Compositions and methods related to the removal of acidic gas. In particular, the present disclosure relates to a composition and method for the removal of acidic gas from a gas mixture using a solvent comprising a diamine (e.g., piperazine) and carbon dioxide. One example of a method may involve a method for removing acidic gas comprising contacting a gas mixture having an acidic gas with a solvent, wherein the solvent comprises piperazine in an amount of from about 4 to about 20 moles/kg of water, and carbon dioxide in an amount of from about 0.3 to about 0.9 moles per mole of piperazine.

Rochelle, Gary (Austin, TX); Hilliard, Marcus (Missouri City, TX)

2011-05-10

305

The History of Acid Inhibition  

E-print Network

I review here the history of inhibition of gastric acid. References are limited to books and reviews in which detailed citations can be found. ANTACIDS In ancient times, acids were not understood in the modem chemical sense but merely as bitter sour liquids [1]. Some foods were thought acidic, and if the stomach had an ulcer, everything acrid was to be avoided and soothing remedies such as starch and milk used. Antacids neutralize, rather than inhibit, acid secretion but could not be rationally prescribed until acids were understood in the modern chemical sense. Hydrochloric acid has been known since the early fifteenth century, thought to be in the stomach by Paracelsus in the sixteenth and by Van Helmont in the seventeenth century, but it was not until 1823 that Prout definitively identified free hydrochloric acid in the gastric juice of man and animals and made quantitative measurements of its concentration. Antacids became widely used only this century, especially in association with Sippytype diets for ulcers [2]. As recently as the 1960s, orthodox gastroenterologists believed that gastric acidity was reduced by minimizing the amount of acid-stimulating foods such

J. H. Barona

1994-01-01

306

Acid rain on acid soil: a new perspective  

Microsoft Academic Search

Acid rain is widely believed to be responsible for acidifying soil and water in areas of North America and northern Europe. However, factors commonly considered to make landscapes susceptible to acidification by acid rain are the same factors long known to strongly acidify soils through the natural processes of soil formation. Recovery from extreme and widespread careless land use has

E. C. Krug; C. R. Frink

1983-01-01

307

Acid zeta function and ajoint acid zeta function  

E-print Network

In this paper we set up the theory of acid zeta function and ajoint acid zeta function, based on the theory, we point out a reason to doubt the truth of the Riemann hypothesis and also as a consequence, we give out some new RH equivalences.

Jining Gao

2010-03-16

308

Peptidases and amino acid catabolism in lactic acid bacteria  

Microsoft Academic Search

The conversion of peptides to free amino acids and their subsequent utilization is a central metabolic activity in prokaryotes. At least 16 peptidases from lactic acid bacteria (LAB) have been characterized biochemically and\\/or genetically. Among LAB, the peptidase systems of Lactobacillus helveticus and Lactococcus lactis have been examined in greatest detail. While there are homologous enzymes common to both systems,

Jeffrey E. Christensen; Edward G. Dudley; Jeffrey A. Pederson; James L. Steele

1999-01-01

309

Fast HPLC-ECD analysis of ascorbic acid, dehydroascorbic acid and uric acid.  

PubMed

A robust and rapid high-pressure liquid chromatography-electrochemical detection (HPLC-ECD) method was developed and validated for the accurate determination of ascorbic acid (AA) and uric acid (UA), in human plasma. Dehydroascorbic acid (DHAA) was indirectly measured by subtracting native ascorbic acid from total ascorbic acid concentrations; the latter was obtained after chemical reduction. A stable electrochemical active internal standard (homogentisic acid) was added for the accurate quantification of the analytes. The analyses were performed on a reverse-phase column with traditional HPLC and ultra-HPLC (UHPLC). The UHPLC method showed increased sensitivity with detection limit of 0.05ng for both AA and UA, 2 times lower compared to conventional HPLC. UHPLC also reduced run times fourfold with less waste generation. Both assays showed good accuracy and precision, the intra- and inter-day CVs of AA and UA analysis are less than 7%. PMID:19250886

Li, Xingnan; Franke, Adrian A

2009-04-01

310

Molecular Structure of Isophthalic acid  

NSDL National Science Digital Library

Isophthalic acid is one of the three simple aromatic dicarboxylic acids with the carboxyl groups in the meta postions. It is used to produce isophthalic polyester that together with other components is used in resin systems for flame retardants and in corrosion prevention.

2008-01-10

311

Acetic Acid Catalyzed Carbon Aerogels  

Microsoft Academic Search

We prepared carbon aerogels with a wide range of structural properties and densities using the weak acetic acid as a catalyst. Two series of acetic acid catalyzed carbon aerogels with different dilution of the catalyst and the monomers were investigated accurately. Structural investigation was performed via (U)SAXS, gas sorption and SEM. The pore and particle size can be tailored according

R. Brandt; R. Petricevic; H. Pröbstle; J. Fricke

2003-01-01

312

Acid rain & electric utilities II  

SciTech Connect

This document presents reports which were presented at the Acid Rain and Electric Utilities Conference. Topics include environmental issues and electric utilities; acid rain program overview; global climate change and carbon dioxide; emissions data management; compliance; emissions control; allowance and trading; nitrogen oxides; and assessment. Individual reports have been processed separately for the United States Department of Energy databases.

NONE

1997-12-31

313

Ricinoleic acid-based biopolymers.  

PubMed

Polyanhydrides synthesized from pure ricinoleic acid half-esters with maleic and succinic anhydrides possess desired physicochemical and mechanical properties for use as drug carriers. Ricinoleic acid maleate or succinate diacid half-esters were prepared from the reaction of crude ricinoleic acid (85% content) with succinic or maleic anhydride. The pure diacid monomers were obtained by chromatography purification through silica gel using petroleum ether/ethyl acetate/acetic acid (80/30/1 v/v/v) mixture as eluent. The pure diacid monomers (>99%) were polymerized by melt condensation to yield film-forming polymers with molecular weights exceeding 40,000 with a polydispersity of 2. Extensive biocompatibility study demonstrated their toxicological inertness and biodegradability. Their rate of elimination from rats in the course of about 4-6 weeks was faster than that found for similar fatty acid-based polyanhydrides previously tested. In vitro studies showed that these polymers underwent rapid hydrolytic degradation in 10 days. Methotrexate release from the polymers was not affected by the initial polymer molecular weight in the range of 10,000-35,000. The in vitro drug release correlated with the degradation of the polymers. The fatty acid ester monomers were further degraded to its counterparts, ricinoleic acid and succinic or maleic acid. PMID:10397984

Teomim, D; Nyska, A; Domb, A J

1999-06-01

314

Acid Precipitation: Causes and Consequences.  

ERIC Educational Resources Information Center

This article is the first of three articles in a series on the acid rain problem in recent years. Discussed are the causes of acid precipitation and its consequences for the abiotic and biotic components of the terrestrial and aquatic ecosystems, and for man-made materials. (Author/SA)

Babich, Harvey; And Others

1980-01-01

315

The Canadian acid rain strategy  

Microsoft Academic Search

In November 1994, Canadian Energy and Environment Ministers announced their intention to develop a long-term domestic acid rain strategy for post-2000. The strategy would address the need for further emission reductions within Canada as well as the need for further emission reductions in the United States for those sources and pollutants that result in continuing negative impacts from acid deposition

G Fenech

1998-01-01

316

The Acid Rain Differential Game  

Microsoft Academic Search

This paper considers an acid rain differential game. Countries emit sulphur which is partly transferred to other countries. Depositions above critical loads ultimately destroy the soil. Countries face a trade-off between the costs of emission reductions and the damage to the soil due to the depletion of the acid buffers. Because of the transboundary externalities the outcome will depend on

Karl-Göran Mäler; Aart De Zeeuw

1998-01-01

317

Acid-Base Titration Applet  

NSDL National Science Digital Library

Acid-Base titration applet that plots pH changes as student adds acid or base. Gives choice of indicators (only two right now). Compares plots for titration of traditional solution and a buffered solution (several choices for comparison). Can alter starting concentrations.

Usc

318

Acid rain: facts and fallacies  

Microsoft Academic Search

Acid rain is a complex environmental problem that is hard to define in terms of sources and effects. Major sources are thought to be atmospheric emissions, mostly from urban sources, although exact locations and the means by which emissions are transformed to acid rain are not entirely clear. Lack of long-term records has made it difficult to determine how fast

1981-01-01

319

Acid Resistance in Mycobacterium tuberculosis  

Microsoft Academic Search

Responses to acid have been studied extensively in enteric pathogens, such as Escherichia coli, Vibrio cholerae, and Heli- cobacter pylori that encounter the extremely low pH (pH 2 to 3) of the stomach during ingestion. In contrast, much less is known about how obligate or facultative intracellular bacterial pathogens like Mycobacterium tuberculosis respond, resist, and persist in the moderately acid

Omar H. Vandal; Carl F. Nathan; Sabine Ehrt

2009-01-01

320

Acid Rain: A Background Report.  

National Technical Information Service (NTIS)

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 meas...

L. Glustrom, J. Stolzenberg

1982-01-01

321

Advanced Lead Acid Battery Development.  

National Technical Information Service (NTIS)

Researchers at the University of Idaho have been investigating the possibility of using lead acid batteries in electric and hybrid vehicles for more than ten years, and the funding from UTC Program helped support this continuing effort. The lead acid batt...

D. Edwards, C. Kinney

2001-01-01

322

SOIL REACTION AND ACIDIC DEPOSITION  

EPA Science Inventory

This chapter discusses the major chemical processes by which acidic deposition interacts with soils. he focus is on forest soils, as the effects of acidic deposition on soils used for production of food and fiber are generally small compared to effects of agricultural practices s...

323

SIMULATED ACID RAIN ON CROPS  

EPA Science Inventory

In 1981, simulated H2SO4 acid rain was applied to alfalfa and tall fescue and a 2:1 ratio of H2SO4:HNO3 acid rain was applied to alfalfa, tall fescue, barley, wheat, potato, tomato, radish, and corn crops growing in the open field at Corvallis, Oregon. Careful attention was given...

324

Bioelectric neutralization of acid waters  

Microsoft Academic Search

An apparatus is to be used in a process for bioelectric neutralization of a body of water having a bottom of anaerobic mud and an acid supernatant liquid. The apparatus comprises a buoy riding on the surface of the water, and upper electrode preferably of carbon suspended from the buoy in the acid supernatant liquid, a lower electrode preferably of

F. D. Sisler; F. E. Senftle

1978-01-01

325

Acetic acid bacteria in oenology  

Microsoft Academic Search

Acetic acid bacteria have always been considered the bad mi- croorganisms of oenology; responsible for wine spoiling (vine- gary taint). The taxonomy and our knowledge of the metabo- lism of acetic acid bacteria are rapidly evolving, especially as new molecular biology techniques are applied to this fastidious group of microorganisms, which are still rather difficult to work with. The dramatic

A. Mas; M. J. Torija; A. González; M. Poblet; J. M. Guillamón

326

Acid Tests and Basic Fun.  

ERIC Educational Resources Information Center

Explores acids and bases using different indicators, such as turmeric, purple grape juice, and lichens. Because some of these indicators are not as sensitive as cabbage juice or litmus paper, determining to which acids and bases each indicator is sensitive presents an enjoyable, problem-solving challenge for students. Presents directions for…

McBride, John W.

1995-01-01

327

Molecular Structure of Formic acid  

NSDL National Science Digital Library

Formic Acid, also known as methanoic acid and hydrogencarboxylic acid, is the simplest organic acid. It is a colorless, toxic, corrosive liquid with a pungent, penetrating odor. In nature, it is found in the stings and bites of many insects of the order hymenoptera, including bees and ants. The principal use of formic acid is as a preservative and antibacterial agent in livestock feed. The largest single use of formic acid is as a silage additive in Europe, but this market hardly exists in the United States. When sprayed on fresh hay or other silage, it arrests certain decay processes and causes the feed to retain its nutritive value longer. In the poultry industry, it is sometimes added to silage to kill salmonella bacteria. It is also used in textile dyeing, leather tanning, as a solvent, in electroplating processes, in the manufacturing of lacquers, glass, vinyl resin plasticizers, and formate esters (for flavor and fragrance) and in the manufacture of fumigants. Formic acid is a strong reducing agent, and may act both as an acid and as an aldehyde because the carboxyl is bound to a hydrogen rather than an alkyl group.

2003-05-08

328

Acid precipitation in historical perspective  

Microsoft Academic Search

The history of acid precipitation is traced from the first awareness of the problem in the mid-17th century to the present. An outline of the National Acid Precipitation Assessment program is also given, and the author makes recommendations for future research. (JMT)

Ellis B. Cowling

1982-01-01

329

BOTANICAL ASPECTS OF ACIDIC PRECIPITATION  

EPA Science Inventory

Acidic precipitation can be characterized as wet or frozen atmospheric deposition with a hydrogen ion concentration greater than 2.5 microequivalents liter-1. Acidic precipitation is perceived as a significant air pollution problem derived chiefly from combustion of fossil fuels,...

330

Distillation Separation of Hydrofluoric Acid and Nitric Acid from Acid Waste Using the Salt Effect on Vapor-Liquid Equilibrium  

NASA Astrophysics Data System (ADS)

This study presents the distillation separation of hydrofluoric acid with use of the salt effect on the vapor-liquid equilibrium for acid aqueous solutions and acid mixtures. The vapor-liquid equilibrium of hydrofluoric acid + salt systems (fluorite, potassium nitrate, cesium nitrate) was measured using an apparatus made of perfluoro alkylvinylether. Cesium nitrate showed a salting-out effect on the vapor-liquid equilibrium of the hydrofluoric acid-water system. Fluorite and potassium nitrate showed a salting-in effect on the hydrofluoric acid-water system. Separation of hydrofluoric acid from an acid mixture containing nitric acid and hydrofluoric acid was tested by the simple distillation treatment using the salt effect of cesium nitrate (45 mass%). An acid mixture of nitric acid (5.0 mol · dm-3) and hydrofluoric acid (5.0 mol · dm-3) was prepared as a sample solution for distillation tests. The concentration of nitric acid in the first distillate decreased from 5.0 mol · dm-3 to 1.13 mol · dm-3, and the concentration of hydrofluoric acid increased to 5.41 mol · dm-3. This first distillate was further distilled without the addition of salt. The concentrations of hydrofluoric acid and nitric acid in the second distillate were 7.21 mol · dm-3 and 0.46 mol · dm-3, respectively. It was thus found that the salt effect on vapor-liquid equilibrium of acid mixtures was effective for the recycling of acids from acid mixture wastes.

Yamamoto, Hideki; Sumoge, Iwao

2011-03-01

331

Atmospheric dust and acid rain  

SciTech Connect

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 rain and atmospheric dust? Suggestions range from the improbable to the feasible. One reasonable suggestion is to reduce emissions of acidic pollutants to levels that can be buffered by natural quantities of basic compounds in the atmosphere; such a goal would mean continued reductions in sulfur dioxide and nitrogen oxides, perhaps even greater than those prescribed in the 1990 Amendments to the Clean Air Act in the U.S. 5 figs.

Hedin, L.O.; Likens, G.E.

1996-12-01

332

Direct formic acid fuel cells  

NASA Astrophysics Data System (ADS)

The performance of formic acid fuel oxidation on a solid PEM fuel cell at 60 °C is reported. We find that formic acid is an excellent fuel for a fuel cell. A model cell, using a proprietary anode catalyst produced currents up to 134 mA/cm 2 and power outputs up to 48.8 mW/cm 2. Open circuit potentials (OCPs) are about 0.72 V. The fuel cell runs successfully over formic acid concentrations between 5 and 20 M with little crossover or degradation in performance. The anodic polarization potential of formic acid is approximately 0.1 V lower than that for methanol on a standard Pt/Ru catalyst. These results show that formic acid fuel cells are attractive alternatives for small portable fuel cell applications.

Rice, C.; Ha, S.; Masel, R. I.; Waszczuk, P.; Wieckowski, A.; Barnard, Tom

333

Fumaric acid production by fermentation.  

PubMed

The potential of fumaric acid as a raw material in the polymer industry and the increment of cost of petroleum-based fumaric acid raises interest in fermentation processes for production of this compound from renewable resources. Although the chemical process yields 112% w/w fumaric acid from maleic anhydride and the fermentation process yields only 85% w/w from glucose, the latter raw material is three times cheaper. Besides, the fermentation fixes CO2. Production of fumaric acid by Rhizopus species and the involved metabolic pathways are reviewed. Submerged fermentation systems coupled with product recovery techniques seem to have achieved economically attractive yields and productivities. Future prospects for improvement of fumaric acid production include metabolic engineering approaches to achieve low pH fermentations. PMID:18214471

Roa Engel, Carol A; Straathof, Adrie J J; Zijlmans, Tiemen W; van Gulik, Walter M; van der Wielen, Luuk A M

2008-03-01

334

Fumaric acid production by fermentation  

PubMed Central

The potential of fumaric acid as a raw material in the polymer industry and the increment of cost of petroleum-based fumaric acid raises interest in fermentation processes for production of this compound from renewable resources. Although the chemical process yields 112% w/w fumaric acid from maleic anhydride and the fermentation process yields only 85% w/w from glucose, the latter raw material is three times cheaper. Besides, the fermentation fixes CO2. Production of fumaric acid by Rhizopus species and the involved metabolic pathways are reviewed. Submerged fermentation systems coupled with product recovery techniques seem to have achieved economically attractive yields and productivities. Future prospects for improvement of fumaric acid production include metabolic engineering approaches to achieve low pH fermentations. PMID:18214471

Roa Engel, Carol A.; Zijlmans, Tiemen W.; van Gulik, Walter M.; van der Wielen, Luuk A. M.

2008-01-01

335

Molecular Structure of Stearic acid  

NSDL National Science Digital Library

Stearic acid is white leaflets, slightly yellow crystal masses or a white to slightly yellow powder. Stearic acid is a saturated fatty acid found in low percentages in cotton, coconut, palm kernel, corn, palm, castor, rapeseed, soybean, sunflower, herring, and tallow oils. It is also one of the fat components found in the cocoa butter of chocolate. It is prepared synthetically by hydrogenation of cottonseed and other vegetable oils or by treating animal fat with water at a high pressure and temperature. Stearic acid is useful as an ingredient in making candles, soaps, and for softening synthetic rubber. It is also a component of cosmetic formulations, pharmaceuticals creams and vanishing lotion. Stearic acid is practically nontoxic but the dust is irritating to eyes, nose, and throat and the solid is irritating to skin and eyes.

2004-11-11

336

Molecular Structure of Galacturonic acid  

NSDL National Science Digital Library

Galacturonic acid is the monobasic acid resulting from oxidation of the primary alcohol group of D-galactose to carboxyl. It is widely distributed as a constituent of pectins (compounds with heterogeneous grouping of acidic structural polysaccharides, found in fruit and vegetables), many plant gums, and mucilages (gummy substances obtained from certain plants, which are used as food stabilizers). Gums tend to be used as thickening and bulking agents in pharmaceutics, and they play a less obvious part in most plants. Once swallowed, their actions are no different from those of the mucilages. D-Galacturonic acid prepared from pectin can be used to synthesize vitamin C. Native pectin is a mixture of polysaccharides, with the major component a polymer of -D-galacturonic acid. Pectin has numerous other medical and pharmaceutical uses, for example in combination with plant hemicelluloses and lignin, may be useful dietary constituents in preventing coronary heart disease, diverticular disease, ulcerative colitis, and a variety of other Western diseases.

2003-05-08

337

Molecular Structure of Linoleic acid  

NSDL National Science Digital Library

Linoleic acid is a polyunsaturated fatty acid occurring widely in plant glycerides or fats. Common sources include many vegetable oils such as flax seed, safflower, soybean, peanut, and corn; some margarines; and dairy fats. It is a colorless to straw-colored liquid, insoluble in water, but soluble in alcohol and ether. Linoleic acid is easily oxidized by air and is combustible. It also appears as an aluminum salt, in the form of yellow lumps or powder, that is practically insoluble in water but soluble in oils and fixed alkalai hydroxides. Linoleic acid is essential in human nutrition and is used also for soaps, animal feeds, paints, drying protective coatings, emulsifying or smoothing and wetting agents, and in biochemical research. The conjugated form of linoleic acid or CLA has been associated with health benefits such as lowered risk of cancer and atherosclerosis. Prepared CLA is available as a supplement. However, foods high in CLA content could be used.

2003-05-08

338

Synthesis of l-(+)-Tartaric Acid from l-Ascorbic Acid via 5-Keto-d-Gluconic Acid in Grapes  

PubMed Central

5-Keto-l-idionic acid (?5-keto-d-gluconic acid, d-xylo-5-hexulosonic acid) was found as a metabolic product of l-ascorbic acid in slices of immature grapes, Vitis labrusca L. cv `Delaware'. Specifically labeled compounds, recognized as metabolic products of l-ascorbic acid in grapes, were fed to young grape tissues to investigate the metabolic pathway from l-ascorbic acid to l-(+)-tartaric acid. Label from dehydro-l-[1-14C]ascorbic acid, 2-keto-l-[1-14C]idonic acid (l-xylo-2-hexulosonic acid), l-[1-14C]idonic acid, or 5-keto-l-[1-14C] idonic acid was incorporated into l-(+)-tartaric acid in high yields as it was in the l-[1-14C]ascorbic acid experiment. In a double label experiment involving a mixture of l-[1-14C]idonic acid and l-[2-3H]idonic acid, the 3H/14C ratios of 5-keto-l-idonic acid and l-(+)-tartaric acid synthesized in young grape leaves were almost the same as the value of the l-idonic acid fed. Label from 5-keto-l-[6-14C]idonic acid was incorporated into sugars and insoluble residue in the same way as l-[6-14C]ascorbic acid was metabolized in grapes. These results provide strong evidence that in grapes l-(+)-tartaric acid is synthesized from the C4 fragment that corresponds to the C1 to C4 group of the 5-keto-l-idonic acid derived from l-ascorbic acid via 2-keto-l-idonic acid and l-idonic acid. PMID:16663792

Saito, Kazumi; Kasai, Zenzaburo

1984-01-01

339

The ascorbic acid paradox.  

PubMed

Ascorbic acid (AA) is a common culture medium and dietary supplement. While AA is most commonly known for its antioxidant properties, it is also known to function as a pro-oxidant under select conditions. However, the complexity and often unknown composition of biological culture systems makes prediction of AA behaviour in supplemented cultures challenging. The frequent observation of outcomes inconsistent with antioxidant behaviour suggests that AA may be playing a pro-oxidant role more often than appreciated. In this work we explored the intracellular and extracellular impact of AA supplementation on KG1a myeloid leukaemia cells over a 24-h culture period following the addition of the AA supplement. At 24h we found that supplementation of AA up to 250?M resulted in intracellular antioxidant behaviour. However, when these same cultures were evaluated at 2 or 4h we observed pro-oxidant activity at the higher AA concentrations indicating that the outcome was very much time and dose dependent. In contrast, pro-oxidant activity was never observed in the extracellular medium. Paradoxically, and to our knowledge not previously reported, we observed that intracellular pro-oxidant activity and extracellular antioxidant activity could occur simultaneously. These results indicate that the precise activity of AA supplementation varies as a function of dose, time and cellular location. Further, these results demonstrate how in the absence of careful culture characterization the true impact of AA on cultures could be underappreciated. PMID:20732307

Osiecki, Michael; Ghanavi, Parisa; Atkinson, Kerry; Nielsen, Lars K; Doran, Michael R

2010-10-01

340

Lead-acid battery  

NASA Technical Reports Server (NTRS)

A light weight lead-acid battery (30) having a positive terminal (36) and a negative terminal (34) and including one or more cells or grid stacks having a plurality of vertically stacked conductive monoplates (10, 20) with positive active material and negative active material deposited on alternating plates in the cell or grid stack. Electrolyte layers (26, 28) positioned between each monoplate are included to provide a battery cell having four sides which is capable of being electrically charged and discharged. Two vertical positive bus bars (42, 43) are provided on opposite sides of the battery cell for connecting the monoplates (10) with positive active material together in parallel current conducting relation. In addition, two negative bus bars (38, 39) on opposite sides of the battery cell each being adjacent the positive bus bars are provided for connecting the monoplates (20) with negative active material together in parallel current conducting relation. The positive (42, 43) and negative (38, 39) bus bars not only provide a low resistance method for connecting the plurality of conductive monoplates of their respective battery terminals (36, 34) but also provides support and structural strength to the battery cell structure. In addition, horizontal orientation of monoplates (10, 20) is provided in a vertical stacking arrangement to reduce electrolyte stratification and short circuiting due to flaking of positive and negative active materials from the monoplates.

Rowlette, John J. (Inventor)

1983-01-01

341

Acid hydrolysis of sugarcane bagasse for lactic acid production.  

PubMed

In order to use sugarcane bagasse as a substrate for lactic acid production, optimum conditions for acid hydrolysis of the bagasse were investigated. After lignin extraction, the conditions were varied in terms of hydrochloric (HCl) or sulfuric (H(2)SO(4)) concentration (0.5-5%, v/v), reaction time (1-5h) and incubation temperature (90-120 degrees C). The maximum catalytic efficiency (E) was 10.85 under the conditions of 0.5% of HCl at 100 degrees C for 5h, which the main components (in gl(-1)) in the hydrolysate were glucose, 1.50; xylose, 22.59; arabinose, 1.29; acetic acid, 0.15 and furfural, 1.19. To increase yield of lactic acid production from the hydrolysate by Lactococcus lactis IO-1, the hydrolysate was detoxified through amberlite and supplemented with 7 g l(-1) of xylose and 7 g l(-1) of yeast extract. The main products (in gl(-1)) of the fermentation were lactic acid, 10.85; acetic acid, 7.87; formic acid, 6.04 and ethanol, 5.24. PMID:19766480

Laopaiboon, Pattana; Thani, Arthit; Leelavatcharamas, Vichean; Laopaiboon, Lakkana

2010-02-01

342

Formation of acrylic acid from lactic acid in supercritical water  

SciTech Connect

Supercritical (SC) water is an unusual medium in which fast and specific heterolytic reactions can be conducted at temperatures as high as 400{degree}C. In supercritical water, lactic acid decomposes into gaseous and liquid products via three primary reaction pathways. Products of the acid-catalyzed heterolytic decarbonylation pathway are carbon monoxide, water, and acetaldehyde. Products of the homolytic, decarboxylation pathway are carbon dioxide, hydrogen, and acetaldehyde. Products of the heterolytic, dehydration pathway are acrylic acid and water. The intramolecular nucleophilic displacement of the {alpha}-hydroxyl by the carbonyl group of lactic acid, producing {alpha}-propiolactone as an unstable intermediate which subsequently rearranges to become the unsaturated acid, is a likely mechanism for acrylic acid formation, although an intramolecular E2 elimination initiated by attack of the carbonyl oxygen on a methyl hydrogen cannot be ruled out. Support for the former mechanism comes in part from the observed 100% relative yield of acrylic acid from {beta}-propiolactone in SC water.

Mok, W.S.L.; Antal, M.J. Jr. (Univ. of Hawaii, Honolulu (USA)); Jones, M. Jr. (Princeton Univ., NJ (USA))

1989-09-15

343

Reduction of hypervalent chromium in acidic media by alginic acid.  

PubMed

Selective oxidation of carboxylate groups present in alginic acid by Cr(VI) affords CO2, oxidized alginic acid, and Cr(III) as final products. The redox reaction afforded first-order kinetics in [alginic acid], [Cr(VI)], and [H(+)], at fixed ionic strength and temperature. Kinetic studies showed that the redox reaction proceeds through a mechanism which combines Cr(VI)?Cr(IV)?Cr(II) and Cr(VI)?Cr(IV)?Cr(III) pathways. The mechanism was supported by the observation of free radicals, CrO2(2+) and Cr(V) as reaction intermediates. The reduction of Cr(IV) and Cr(V) by alginic acid was independently studied and it was found to occur more than 10(3) times faster than alginic acid/Cr(VI) reaction, in acid media. At pH 1-3, oxo-chromate(V)-alginic acid species remain in solution during several hours at 15°C. The results showed that this abundant structural polysaccharide present on brown seaweeds is able to reduce Cr(VI/V/IV) or stabilize high-valent chromium depending on pH value. PMID:25263857

Bertoni, Fernando A; Bellú, Sebastian E; González, Juan C; Sala, Luis F

2014-12-19

344

Kinetics of aluminum-fulvic acid complexation in acidic waters  

SciTech Connect

A fluorescence technique has been used to study the complex formation kinetics of aluminum with a single metal-free fulvic acid isolated from an Adirondack Mountain forest soil. In the pH range of 3.0-4.5, two kinetically distinguishable components of the fulvic acid mixture have been identified, which define two types of average aluminum binding sites. Both fulvic acid average sites conform to a bidentate chelating binding site kinetic analysis, from which rate and equilibrium parameters have been obtained. From comparison of rate and equilibrium constants of aluminum-salicyclic acid complexation, the authors conclude that the faster reacting component of fulvic acid probably contains salicyclic acid type aluminum binding sites. Results are also compared with those of an aluminum-fluoride kinetic study. Fulvic acid and fluoride react with aluminum by the same mechanism and therefore have the same pH dependence. The dependence of the rate on temperature is, however, quite different for the two reactions. The environmental implications of these findings are discussed. 45 references, 5 figures, 6 tables.

Plankey, B.J.; Patterson, H.H.

1987-06-01

345

?-Oxidation of ?-Chlorinated Fatty Acids  

PubMed Central

Myeloperoxidase-derived HOCl targets tissue- and lipoprotein-associated plasmalogens to generate ?-chlorinated fatty aldehydes, including 2-chlorohexadecanal. Under physiological conditions, 2-chlorohexadecanal is oxidized to 2-chlorohexadecanoic acid (2-ClHA). This study demonstrates the catabolism of 2-ClHA by ?-oxidation and subsequent ?-oxidation from the ?-end. Mass spectrometric analyses revealed that 2-ClHA is ?-oxidized in the presence of liver microsomes with initial ?-hydroxylation of 2-ClHA. Subsequent oxidation steps were examined in a human hepatocellular cell line (HepG2). Three different ?-chlorinated dicarboxylic acids, 2-chlorohexadecane-(1,16)-dioic acid, 2-chlorotetradecane-(1,14)-dioic acid, and 2-chloroadipic acid (2-ClAdA), were identified. Levels of 2-chlorohexadecane-(1,16)-dioic acid, 2-chlorotetradecane-(1,14)-dioic acid, and 2-ClAdA produced by HepG2 cells were dependent on the concentration of 2-ClHA and the incubation time. Synthetic stable isotope-labeled 2-ClHA was used to demonstrate a precursor-product relationship between 2-ClHA and the ?-chlorinated dicarboxylic acids. We also report the identification of endogenous 2-ClAdA in human and rat urine and elevations in stable isotope-labeled urinary 2-ClAdA in rats subjected to intraperitoneal administration of stable isotope-labeled 2-ClHA. Furthermore, urinary 2-ClAdA and plasma 2-ClHA levels are increased in LPS-treated rats. Taken together, these data show that 2-ClHA is ?-oxidized to generate ?-chlorinated dicarboxylic acids, which include ?-chloroadipic acid that is excreted in the urine. PMID:20956542

Brahmbhatt, Viral V.; Albert, Carolyn J.; Anbukumar, Dhanalakshmi S.; Cunningham, Bryce A.; Neumann, William L.; Ford, David A.

2010-01-01

346

Analysis of Acidic Drugs in Swiss Wastewaters  

Microsoft Academic Search

Five acidic drugs (clofibric acid, ibuprofen, ketoprofen, mefenamic acid and diclofenac) were chosen in order to determine their behavior in a sewage treatment plant (STP). An analytical method using solid phase extraction (SPE) and a gas chromatograph coupled with a mass spectrometer (GC-MS) was used. The results show that four pharmaceuticals (clofibric acid, ketoprofen, mefenamic acid and diclofenac) are not

Benedicte Soulet; Annick Tauxe; Joseph Tarradellas

2002-01-01

347

Combined Acid Catalysis for Asymmetric Synthesis  

E-print Network

Combined Acid Catalysis for Asymmetric Synthesis Michael T. Corbett University of North Carolina, 44, 1924­1942. Limitations of classical Brønsted/Lewis Acid catalysis: · Poor reactivity (low acidity) · Low selectivity · High catalyst loading R X R X HMLn X Lewis Acid Catalysis Brønsted Acid Catalysis X

Johnson, Jeff S.

348

ACID RAIN DEGRADATION OF NYLON (POLYAMIDE, PHOTODEGRADATION)  

Microsoft Academic Search

Acid rain, precipitation with a ph less than 5.6, is known to damage lakes, vegetation and buildings. Degradation of outdoor textiles by acid rain is strongly suspected but not well documented. This study reports the effects of sunlight, aqueous acid, heat and humidity (acid rain conditions) on spun delustered nylon 6,6 fabric. Untreated nylon and nylon treated with sulfuric acid

KAREN E KYLLO

1984-01-01

349

Terahertz spectrum of gallic acid  

NASA Astrophysics Data System (ADS)

Gallic acid is natural polyphenol compound found in many green plants. More and more experiments have demonstrated that the gallic acid has comprehensive applications. In the field of medicine, the gallic acid plays an important role in antianaphylaxis, antineoplastic, antimycotic, anti-inflammatory, antivirotic, antiasthmatic and inhibiting the degradation of insulin. It also has a lot of applications in chemical industry, food industry and light industry. So it is important to study the terahertz time-domain spectroscopy of gallic acid. Terahertz time-domain spectroscopy (THz-TDS) is a new coherent spectral technology based on the femtosecond laser. In this work, the spectral characteristics of gallic acid in the range of 0.4 THz to 2.6 THz have been measured by THz-TDS. We obtained its absorption and refraction spectra at room temperature. The vibration absorption spectrum of the single molecule between 0.4 THz and 2.6 THz is simulated based on the Density Functional Theory (DFT). It is found that the gallic acid has the spectral response to THz wave in this frequency range. The results show the abnormal dispersion at 1.51 THz and 2.05 THz. These results can be used in the qualitative analysis of gallic acid and the medicine and food inspection.

Wu, Meng; Zhao, Guozhong; Wang, Haiyan; Liang, Chengshen

2009-11-01

350

Diabetes and Alpha Lipoic Acid  

PubMed Central

Diabetes mellitus is a multi-faceted metabolic disorder where there is increased oxidative stress that contributes to the pathogenesis of this debilitating disease. This has prompted several investigations into the use of antioxidants as a complementary therapeutic approach. Alpha lipoic acid, a naturally occurring dithiol compound which plays an essential role in mitochondrial bioenergetic reactions, has gained considerable attention as an antioxidant for use in managing diabetic complications. Lipoic acid quenches reactive oxygen species, chelates metal ions, and reduces the oxidized forms of other antioxidants such as vitamin C, vitamin E, and glutathione. It also boosts antioxidant defense system through Nrf-2-mediated antioxidant gene expression and by modulation of peroxisome proliferator activated receptors-regulated genes. ALA inhibits nuclear factor kappa B and activates AMPK in skeletal muscles, which in turn have a plethora of metabolic consequences. These diverse actions suggest that lipoic acid acts by multiple mechanisms, many of which have only been uncovered recently. In this review we briefly summarize the known biochemical properties of lipoic acid and then discussed the oxidative mechanisms implicated in diabetic complications and the mechanisms by which lipoic acid may ameliorate these reactions. The findings of some of the clinical trials in which lipoic acid administration has been tested in diabetic patients during the last 10?years are summarized. It appears that the clearest benefit of lipoic acid supplementation is in patients with diabetic neuropathy. PMID:22125537

Golbidi, Saeid; Badran, Mohammad; Laher, Ismail

2011-01-01

351

Determination of polyfluoroalkyl phosphoric acid diesters, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, perfluoroalkyl carboxylic acids, and perfluoroalkane sulfonic acids in lake trout from the Great Lakes region.  

PubMed

A comprehensive method to extract perfluoroalkyl carboxylic acids, perfluoroalkane sulfonic acids, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, and polyfluoroalkyl phosphoric acid diesters simultaneously from fish samples has been developed. The recoveries of target compounds ranged from 78 % to 121 %. The new method was used to analyze lake trout (Salvelinus namaycush) from the Great Lakes region. The results showed that the total perfluoroalkane sulfonate concentrations ranged from 0.1 to 145 ng/g (wet weight) with perfluorooctane sulfonate (PFOS) as the dominant contaminant. Concentrations in fish between lakes were in the order of Lakes Ontario ? Erie > Huron > Superior ? Nipigon. The total perfluoroalkyl carboxylic acid concentrations ranged from 0.2 to 18.2 ng/g wet weight. The aggregate mean perfluorooctanoic acid (PFOA) concentration in fish across all lakes was 0.045 ± 0.023 ng/g. Mean concentrations of PFOA were not significantly different (p > 0.1) among the five lakes. Perfluoroalkyl phosphinic acids were detected in lake trout from Lake Ontario, Lake Erie, and Lake Huron with concentration ranging from non-detect (ND) to 0.032 ng/g. Polyfluoroalkyl phosphoric acid diesters were detected only in lake trout from Lake Huron, at levels similar to perfluorooctanoic acid. PMID:22722738

Guo, Rui; Reiner, Eric J; Bhavsar, Satyendra P; Helm, Paul A; Mabury, Scott A; Braekevelt, Eric; Tittlemier, Sheryl A

2012-11-01

352

Acidity dependence of the trifluoromethanesulfonic acid catalyzed isobutane-isobutylene alkylation modified with trifluoroacetic acid or water  

Microsoft Academic Search

Trifluoromethanesulfonic acid (TFSA) catalyzed isobutane-isobutylene alkylation modified with trifluoroacetic acid (TFA) or water, was studied over a wide range of acidity (Ho: ?10.1 to ?14.1). The effect of the acidity of these nonoxidizing strong mixed acid systems on the alkylation, is reported. For both systems, the best alkylation conditions were those at an acid strength of about Ho= ?10.7, giving

George A. Olah; Patrice Batamack; Denis Deffieux; Béla Török; Qi Wang; Árpád Molnár; G. K. Surya Prakash

1996-01-01

353

40 CFR 721.2086 - Coco acid triamine condensate, polycarboxylic acid salts.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Coco acid triamine condensate, polycarboxylic acid salts. 721.2086 Section 721.2086 Protection...Specific Chemical Substances § 721.2086 Coco acid triamine condensate, polycarboxylic acid...

2013-07-01

354

Solid acids for green chemistry.  

PubMed

Solid acids and especially those based on micelle-templated silicas and other mesoporous high surface area support materials are beginning to play a significant role in the greening of fine and specialty chemicals manufacturing processes. A wide range of important organic reactions can be efficiently catalyzed by these materials, which can be designed to provide different types of acidity as well as high degrees of reaction selectivity. The solid acids generally have high turnover numbers and can be easily separated from the organic components. The combination of this chemistry with innovative reaction engineering offers exciting opportunities for innovative green chemical manufacturing in the future. PMID:12234209

Clark, James H

2002-09-01

355

Treatment of acid mine wastewaters  

SciTech Connect

Acid mine drainage often results from the oxidation sulfide minerals to form sulfuric acid. As a consequence, high concentrations of metals in the both the suspended and dissolved state result from the low pH water. This paper discusses several of the more common treatment methods for acid mine drainage including the use of chemical precipitation agents, pH correction agents, filtration methods, and biodegradation methods. Advanced treatment technologies are also briefly described and include microfiltration, reverse osmosis, ion exchange, and electrodialysis.

Hayward, D.; Barnard, R.

1993-06-01

356

Can crops tolerate acid rain  

SciTech Connect

This brief article describes work by scientists at the ARS Air Quality-Plant Growth and Development Laboratory in Raleigh, North Carolina, that indicates little damage to crops as a result of acid rain. In studies with simulated acid rain and 216 exposed varieties of 18 crops, there were no significant injuries nor was there reduced growth in most species. Results of chronic and acute exposures were correlated in sensitive tomato and soybean plants and in tolerant winter wheat and lettuce plants. These results suggest that 1-hour exposures could be used in the future to screen varieties for sensitivity to acid rain.

Kaplan, J.K.

1989-11-01

357

Chemiluminescent measurement of atmospheric acid  

NASA Technical Reports Server (NTRS)

The design and construction of a gas phase acid sensitive analyzer are reported. These studies showed that the chemical system was a practical analytical method. A complete instrument was developed and prepared for field testing. A Titan 3-C rocket was scheduled for launching on February 11, 1974. Through preparations made by NASA Langley the instrument was set up to monitor the acid concentration in the rocket exhaust. Due to adverse wind conditions no acid was detected. This entire trip is described in detail.

Stedman, D. H.; Kok, G. L.

1974-01-01

358

Be an acid rain detective  

SciTech Connect

Acid rain is discussed in a question and answer format. The article is aimed at educating sport fishermen on the subject, and also to encourage them to write their congressmen, senators, and the President about the acid rain problem. The article also announces the availability of an acid rain test kit available through the magazine, ''Sports Afield.'' The kit consists of pH-test paper that turns different shades of pink and blue according to the pH of the water tested. The color of the test paper is then compared to a color chart furnished in the kit and an approximate pH can be determined.

Atwill, L.

1982-07-01

359

Organic acids enhance halogen activation on mildly acidic water surfaces  

NASA Astrophysics Data System (ADS)

Iodine species of marine origin are ubiquitous in the marine boundary layer (MBL). They are found over the open ocean (even in the absence of biogenic sources), the Antarctic coast, in rain, aerosols, ice, and snow, and participate in HOx/NOx cycles in the MBL. Surface-active organic acids coating the surface marine microlayer (SML) and marine aerosols could affect their chemical/physical properties. Recent field measurements show that organic acids represent ˜50% of the mass of fog waters collected in the US Gulf Coast. Here we report that I2(g) emissions from the heterogeneous reactions of O3(g) with I- (aq) are dramatically enhanced in the presence of surface-active organic acids under mildly acidic condition that are typical of fine marine aerosols. The amphiphilic weak carboxylic acids appear to promote I2(g) emissions by donating the interfacial protons more efficiently than water itself. We infer that the organic acids coating aerosol particles ejected from ocean's surface films could enhance I2(g) production in the MBL.

Hayase, S.; Enami, S.; Yabushita, A.; Kawasaki, M.; Hoffmann, M. R.; Colussi, A. J.

2011-12-01

360

Genetics Home Reference: Sialic acid storage disease  

MedlinePLUS

... testing OMIM Genetic disorder catalog Conditions > Sialic acid storage disease On this page: Description Genetic changes Inheritance ... definitions Reviewed February 2008 What is sialic acid storage disease? Sialic acid storage disease is an inherited ...

361

Background on Net Acid or ARD Potential  

E-print Network

balance that favours net acidity or net alkalinity #12;01-3 ABA Method · For example, we want to calculate acid generating and the amount of acid is determined by titration and expressed in the same units

Boisvert, Jeff

362

Separation of saturated\\/unsaturated fatty acids  

Microsoft Academic Search

Fatty acid mixtures can be separated into one fraction rich in saturated fatty acids and the other rich in unsaturated acids.\\u000a Since saturated fatty acids have a higher melting point than unsaturated, liquid mixture to be fractionated is cooled to a\\u000a temperature at which the larger part of the saturated acids crystallize, while the greater part of unsaturated acids remain

G. Haraldsson

1984-01-01

363

Quantitative Paper Partition Chromatography of Sialic Acids  

Microsoft Academic Search

RECENTLY, it has been obvious that in most biological materials N-acetylsialic acid (N-acetyl-neuraminic acid) and N-glycolloylsialic acid occur together. By the introduction of a micromethod for the determination of glycollic acid, Klenk and Uhlenbruck1 have made possible the evaluation of the amount of N-glycolloylsialic acid in isolated sialic acids. In search of a more direct method, we tried partition chromatography,

Elisabet Svennerholm; Lars Svennerholm

1958-01-01

364

Nucleic acid arrays and methods of synthesis  

DOEpatents

The present invention generally relates to high density nucleic acid arrays and methods of synthesizing nucleic acid sequences on a solid surface. Specifically, the present invention contemplates the use of stabilized nucleic acid primer sequences immobilized on solid surfaces, and circular nucleic acid sequence templates combined with the use of isothermal rolling circle amplification to thereby increase nucleic acid sequence concentrations in a sample or on an array of nucleic acid sequences.

Sabanayagam, Chandran R. (Allston, MA); Sano, Takeshi (Needham, MA); Misasi, John (Syracuse, NY); Hatch, Anson (Seattle, WA); Cantor, Charles (Del Mar, CA)

2001-01-01

365

Acidic Deposition: Sources and Ecological Effects  

Microsoft Academic Search

Acidic atmospheric deposition, popularly referred to as acid rain, is the transfer of strong acids and acid forming substances\\u000a from the atmosphere to the Earth’s surface. Acidic deposition is comprised of sulfuric and nitric acids, and ammonium derived\\u000a from atmospheric emissions of sulfur dioxide, nitrogen oxides, and ammonia respectively. These compounds are emitted by the\\u000a burning of fossil fuels and

Charles T. Driscoll; Kathy Fallon Lambert; Limin Chen

366

Seasonalepisodic control of acid deposition  

E-print Network

This report contains the climatological, technical and economic factors for episodic and seasonal control of emissions in existing power plants. Analyzing a large data set of acid deposition for the years 1982-85, we find ...

Fay, James A.

1988-01-01

367

Controlling acid rain : policy issues  

E-print Network

The policy and regulatory ramifications of U.S. acid rain control programs are examined; particularly, the alternative of a receptor-oriented strategy as constrasted to emission-oriented proposals (e.g., the Mitchell bill) ...

Fay, James A.

1983-01-01

368

Low acid producing solid propellants  

NASA Technical Reports Server (NTRS)

The potential environmental effects of the exhaust products of conventional rocket propellants have been assessed by various groups. Areas of concern have included stratospheric ozone, acid rain, toxicity, air quality and global warming. Some of the studies which have been performed on this subject have concluded that while the impacts of rocket use are extremely small, there are propellant development options which have the potential to reduce those impacts even further. This paper discusses the various solid propellant options which have been proposed as being more environmentally benign than current systems by reducing HCI emissions. These options include acid neutralized, acid scavenged, and nonchlorine propellants. An assessment of the acid reducing potential and the viability of each of these options is made, based on current information. Such an assessment is needed in order to judge whether the potential improvements justify the expenditures of developing the new propellant systems.

Bennett, Robert R.

1995-01-01

369

Molecular Structure of Abscisic acid  

NSDL National Science Digital Library

Abscisic acid (ABA) was first identified and characterized by Frederick Addicott in 1963. ABA is a naturally occurring compound in plants synthesized partially in the chloroplasts. It is a phytohormone that plays an important role in regulating transpiration, stress responses, germination of seeds and embryogenesis in plants. Abscisic acid influences most aspects of plant growth and development to some level, in part due to interactions with other phytohormones. Abscisic acid also promotes abscission of leaves and fruits, and for this reason the name abscisic is given. This plant hormone is the key factor in the adaptation of the plant to environmental stresses such as salinity, drought or water loss, and freezing temperatures. Abscisic acid promotes dormancy and helps the plant tolerate stressful conditions by suspending primary and secondary growth.

2004-11-09

370

Nitrate and Prussic Acid Poisoning  

E-print Network

Nitrate and prussic acid poisoning in cattle are noninfectious conditions that can kill livestock. This publication explains the causes and symptoms of these conditions as well as preventive measures and sampling and testing steps....

Stichler, Charles; Reagor, John C.

2001-09-05

371

Abiotic synthesis of fatty acids  

NASA Technical Reports Server (NTRS)

The formation of fatty acids by Fischer-Tropsch-type synthesis was investigated with ferric oxide, ammonium carbonate, potassium carbonate, powdered Pueblito de Allende carbonaceous chondrite, and filings from the Canyon Diablo meteorite used as catalysts. Products were separated and identified by gas chromatography and mass spectrometry. Iron oxide, Pueblito de Allende chondrite, and Canyon Diablo filings in an oxidized catalyst form yielded no fatty acids. Canyon Diablo filings heated overnight at 500 C while undergoing slow purging by deuterium produced fatty acids only when potassium carbonate was admixed; potassium carbonate alone also produced these compounds. The active catalytic combinations gave relatively high yields of aliphatic and aromatic hydrocarbons; substantial amounts of n-alkenes were almost invariably observed when fatty acids were produced; the latter were in the range C6 to C18, with maximum yield in C9 or 10.

Leach, W. W.; Nooner, D. W.; Oro, J.

1978-01-01

372

New syntheses of aminoalkylphosphonic acids  

E-print Network

. Because of the ease of formation of diethyl phosphono- acetamide (XII a) from triethyl phosphonoacetate (Vp a), this amide . was chosen for use in the initial preparation of an amino phosphonic acid by the Hofmann reaction. However, each of several.... Because of the ease of formation of diethyl phosphono- acetamide (XII a) from triethyl phosphonoacetate (Vp a), this amide . was chosen for use in the initial preparation of an amino phosphonic acid by the Hofmann reaction. However, each of several...

DeBardeleben, John Frederick

2012-06-07

373

Acid Acclimation by Helicobacter pylori  

NSDL National Science Digital Library

Helicobacter pylori is a Gram-negative neutralophile associated with peptic ulcers and gastric cancer. It has a unique ability to colonize the human stomach by acid acclimation. It uses the pH-gated urea channel, UreI, to enhance urea access to intrabacterial urease and a membrane-anchored periplasmic carbonic anhydrase to regulate periplasmic pH to ~6.1 in acidic media, whereas other neutralophiles cannot regulate periplasmic pH and thus only transit the stomach.

PhD George Sachs (VA Wadsworth Hospital Center for Ulcer Research); David L. Weeks (University of California-Los Angeles David Geffen School of Medicine); Yi Wen (University of California-Los Angeles David Geffen School of Medicine); Elizabeth A. Marcus (University of California-Los Angeles David Geffen School of Medicine); David R. Scott (University of California-Los Angeles David Geffen School of Medicine); Klaus Melchers (Altana Research Institute)

2005-12-01

374

Annual zoledronic acid for osteoporosis.  

PubMed

Zoledronic acid (Aclasta - Novartis) is the first bisphosphonate to be licensed in the UK as a once-yearly intravenous treatment for women with postmenopausal osteoporosis. Promotional materials claim that the drug "provides powerful osteoprotection with yearlong compliance", with "significant 3 year fracture reduction at all key sites". Here we consider whether zoledronic acid has a role in the treatment of women with postmenopausal osteoporosis. PMID:19056701

2008-12-01

375

BranchedChain Amino Acids  

Microsoft Academic Search

The branched-chain amino acids (BCAAs) leucine, isoleucine, and valine are synthesized by bacteria,\\u000a fungi, and plants, but are essential for vertebrates including humans, who must receive them from their\\u000a diet. The interest to construct overproducing industrial strains therefore stems from the need to supplement\\u000a the food or feed with these amino acids to use them in medical treatment and as

Miroslav Pátek

376

Molecular Structure of Glucuronic acid  

NSDL National Science Digital Library

Glucuronic acid is a substance derived from uronic acid, and is found in both plants and animals, usually in combination with phenols or alcohols. It is primarily used in detoxifying drugs and toxins to ensure easy elimination from the body. This substance is soluble in water and alcohol and has a melting point of 165 degrees Celsius. It exhibits mutarotation in the crystal form or its specific rotation of light changes depending on the way the crystals were prepared.

2003-05-08

377

Rainfall acidity in northern Britain  

Microsoft Academic Search

The acidity of rain has attracted considerable international interest during the past decade. An area of enhanced rainfall acidity with its focus in the Low Countries of north-west Europe was identified by the European air chemistry study1 for the period 1955-68, and widespread concern arose as a result of observations that fish populations were decreasing in areas of Scandinavia subject

D. Fowler; J. N. Cape; I. D. Leith; I. S. Paterson; J. W. Kinnaird; I. A. Nicholson

1982-01-01

378

Chemical composition of acid fog  

SciTech Connect

Fog water collected at three sites in Los Angeles and Bakersfield, California, was found to have higher acidity and higher concentrations of sulfate, nitrate, and ammonium than previously observed in atmospheric water droplets. The pH of the fog water was in the range of 2.2 to 4.0. the dominant processes controlling the fog water chemistry appear to be the condensation and evaporation of water vapor on preexisting aerosol and the scavenging of gas-phase nitric acid.

Waldman, J.M.; Munger, J.W.; Jacob, D.J.; Flagan, R.C.; Morgan, J.J.; Hoffmann, M.R.

1982-11-12

379

ACID HYDROLYSIS OF AZIRIDINYL PHOSPHORAMIDES  

Microsoft Academic Search

The acid hydrolysis of two model aziridinyl phosphoramides, l-aziridinylbis(dimethylamino)phosphine oxide (11) and bis(l-aziridinyl) (dimethylamino)phosphine oxide (16), in aqueous acetic acid proceeded by an initial aziridine ring opening to give 2-hydroxyethyl phosphoramides 12 and 17, respectively. These intermediates rapidly cyclized to an oxazaphospholidine ring structure 13 or 18, with the subsequent loss of dimethylamine or aziridine. Analysis of ongoing hydrolysis showed

Jerry B. Stokes; Charles W. Woods; Alexej B. Borkovec

1981-01-01

380

Radiolysis of sulfuric acid, sulfuric acid monohydrate, and sulfuric acid tetrahydrate and its relevance to Europa  

Microsoft Academic Search

We report laboratory studies on the 0.8MeV proton irradiation of ices composed of sulfuric acid (H2SO4), sulfuric acid monohydrate (H2SO4·H2O), and sulfuric acid tetrahydrate (H2SO4·4H2O) between 10 and 180K. Using infrared spectroscopy, we identify the main radiation products as H2O, SO2, (S2O3)x, H3O+, HSO4-, and SO42-. At high radiation doses, we find that H2SO4 molecules are destroyed completely and that

M. J. Loeffler; R. L. Hudson; M. H. Moore; R. W. Carlson

2011-01-01

381

Digestion and absorption of polyunsaturated fatty acids  

E-print Network

bring to light the esterification step, particularly the integration of polyunsatura- ted fatty acids. polyunsaturated fatty acid / digestion / absorption pathway / enterocyte esterification / intesti- nal lipoprotein

Boyer, Edmond

382

Acidic extracellular microenvironment and cancer.  

PubMed

Acidic extracellular pH is a major feature of tumor tissue, extracellular acidification being primarily considered to be due to lactate secretion from anaerobic glycolysis. Clinicopathological evidence shows that transporters and pumps contribute to H+ secretion, such as the Na+/H+ exchanger, the H+-lactate co-transporter, monocarboxylate transporters, and the proton pump (H+-ATPase); these may also be associated with tumor metastasis. An acidic extracellular pH not only activates secreted lysosomal enzymes that have an optimal pH in the acidic range, but induces the expression of certain genes of pro-metastatic factors through an intracellular signaling cascade that is different from hypoxia. In addition to lactate, CO2 from the pentose phosphate pathway is an alternative source of acidity, showing that hypoxia and extracellular acidity are, while being independent from each other, deeply associated with the cellular microenvironment. In this article, the importance of an acidic extracellular pH as a microenvironmental factor participating in tumor progression is reviewed. PMID:24004445

Kato, Yasumasa; Ozawa, Shigeyuki; Miyamoto, Chihiro; Maehata, Yojiro; Suzuki, Atsuko; Maeda, Toyonobu; Baba, Yuh

2013-01-01

383

Acidic extracellular microenvironment and cancer  

PubMed Central

Acidic extracellular pH is a major feature of tumor tissue, extracellular acidification being primarily considered to be due to lactate secretion from anaerobic glycolysis. Clinicopathological evidence shows that transporters and pumps contribute to H+ secretion, such as the Na+/H+ exchanger, the H+-lactate co-transporter, monocarboxylate transporters, and the proton pump (H+-ATPase); these may also be associated with tumor metastasis. An acidic extracellular pH not only activates secreted lysosomal enzymes that have an optimal pH in the acidic range, but induces the expression of certain genes of pro-metastatic factors through an intracellular signaling cascade that is different from hypoxia. In addition to lactate, CO2 from the pentose phosphate pathway is an alternative source of acidity, showing that hypoxia and extracellular acidity are, while being independent from each other, deeply associated with the cellular microenvironment. In this article, the importance of an acidic extracellular pH as a microenvironmental factor participating in tumor progression is reviewed. PMID:24004445

2013-01-01

384

Magnesium and arachidonic acid metabolism.  

PubMed

The arachidonic acid content of plasma lipoproteins is altered during dietary magnesium deficiency, although the tissue arachidonic acid content seems to be unchanged. The primary event triggering these changes is probably the loss of extracellular Mg2+, as it is not clear whether dietary magnesium deficiency produces loss of intracellular Mg2+. In the isolated rabbit heart, in vitro perfusion conditions which produce loss of intracellular Mg2+ also result in disturbances of arachidonic acid metabolism. The metabolism of exogenous arachidonic acid to prostaglandins is increased without changing the Km or Vmax of cyclo-oxygenase. The incorporation of arachidonic acid into tissue phospholipids is significantly reduced, although the incorporation of oleate, stearate, and linolenate is either increased or unchanged. These data indicate that the activity of the enzymes (CoA synthetases and acyl transferases) which mediate arachidonate incorporation is reduced during Mg2+ depletion. Since protein-kinase-C-mediated phosphorylation of both CoA synthetase and acyl transferase reduces their activity, and since protein kinase C has an Mg2+ binding site, it is possible to speculate that loss of intracellular Mg2+ may lead to the activation of protein kinase C, with the consequent reduction of arachidonic acid reacylation enzyme activity. PMID:8274364

Weis, M T; Saunders, C

1993-06-01

385

Molecular Structure of Oxalic acid  

NSDL National Science Digital Library

Oxalic acid is an odorless, colorless powder or granular solid. It is used as a scouring agent in textiles for finishing, stripping, cleaning, and as a bleaching agent for stain removal. Oxalic acid is also used as a rust remover as well as a grease and wax removing agent in metal cleaning. It is also used to clean and sterilize equipment, slso as a purifying agent in the pharmaceutical industry, in the waste water treatment industry and is also used to remove calcium from water. Oxalic acid is found in many plants and in many vegetables, for example sorrel, spinach and rhubarb, usually as its calcium or potassium salts. Oxalic acid is produced commercially by nitric acid oxidation of starch. It also can be made by fusing sawdust (or other forms of cellulose) with a mixture of sodium hydroxide and potassium hydroxide. Oxalic acid may be released to the environment in tobacco smoke, automobile exhaust, rendering, in waste streams from pulp bleaching, and by photochemical oxidations of anthropogenic compounds during long range transport.

2004-11-10

386

A Study of the Acid Properties of Structurally and Compositionally Different Heteropoly Acids in Acetic Acid  

Microsoft Academic Search

The acid properties of heteropoly acids of the following three structure types were studied by conductometry in acetic acid: Keggin (H3PW12O40, H3PMo12O40, H4SiW12O40, H3PW11ThO39; and H5PW11XO40, where X(IV) = Ti or Zr), Dawson (a-H6P2W18O62and a-H6P2Mo18O62), and H6P2W21O71(H2O)3. These compounds are electrolytes that dissociate in only the first step of this solvent. The thermodynamic dissociation constants of the heteropoly acids were

M. N. Timofeeva; M. M. Matrosova; G. M. Maksimov; V. A. Likholobov

2001-01-01

387

Polypyrrole based strong acid catalyst for acetalization  

NASA Astrophysics Data System (ADS)

Novel polypyrrole based acid catalyst has been synthesized through the neutralization reaction of polypyrrole and sulfuric acid. The polypyrrole based acid owned the acidity as high as 6.0 mmol/g, which was much higher than that of the traditional solid acids such as Nafion and Amberlyst-15 (0.8 mmol/g). The catalytic activities of the novel solid acid were investigated through the acetalization. The results showed that the novel solid acid held high activities for the reactions. Furthermore, the recycled activities of the catalyst indicated that the solid acid owned high stability during the catalytic process and little acid sites dropped from polypyrrole. The high acidity and stability made the novel polypyrrole based acid hold great potential for the green chemical processes.

Liang, Xuezheng; Cheng, Yuxiao; Qi, Chenze

2011-09-01

388

Bile acids: regulation of apoptosis by ursodeoxycholic acid  

PubMed Central

Bile acids are a group of molecular species of acidic steroids with peculiar physical-chemical and biological characteristics. At high concentrations they become toxic to mammalian cells, and their presence is pertinent in the pathogenesis of several liver diseases and colon cancer. Bile acid cytoxicity has been related to membrane damage, but also to nondetergent effects, such as oxidative stress and apoptosis. Strikingly, hydrophilic ursodeoxycholic acid (UDCA), and its taurine-conjugated form (TUDCA), show profound cytoprotective properties. Indeed, these molecules have been described as potent inhibitors of classic pathways of apoptosis, although their precise mode of action remains to be clarified. UDCA, originally used for cholesterol gallstone dissolution, is currently considered the first choice therapy for several forms of cholestatic syndromes. However, the beneficial effects of both UDCA and TUDCA have been tested in other experimental pathological conditions with deregulated levels of apoptosis, including neurological disorders, such as Alzheimer's, Parkinson's, and Huntington's diseases. Here, we review the role of bile acids in modulating the apoptosis process, emphasizing the anti-apoptotic effects of UDCA and TUDCA, as well as their potential use as novel and alternate therapeutic agents for the treatment of apoptosis-related diseases. PMID:19417220

Amaral, Joana D.; Viana, Ricardo J. S.; Ramalho, Rita M.; Steer, Clifford J.; Rodrigues, Cecilia M. P.

2009-01-01

389

Fatty Acids, Antibiotic Resistance, and Deoxyribonucleic Acid Homology Groups of Bradyrhizobiurn japonicum  

Microsoft Academic Search

The fatty acid compositions and multiple antibiotic resistance patterns of 32 strains of Bradyrhizobium japonicum correlated with two major deoxyribonucleic acid homology groups. In group I, the fatty acid composition was 1.3% 16:l cis9 acid, 3.6% 16:lC acid, 8.8% 16:O acid, 1.2% 19:0 cyclopropane acid, and 81.2% 18:l acid. Group I1 contained 0.5% 16:lC acid, 11.1% 16:O acid, 0.8% 17:O

L. D. KUYKENDALL; M. A. ROY; J. J. O'NEILL

390

Kinetic and safety assessment for salicylic acid nitration by nitric acid/acetic acid system.  

PubMed

The nitration process of salicylic acid for the production of the important intermediate 5-nitrosalicylic acid is studied from thermokinetic and safety points of view. Investigations carried out by considering, as process deviations, the loss of the thermal control point out the possibility of runaway phenomena due to the occurrence of polynitration reactions. Isothermal experiments are carried out in various conditions to assess the involved reaction network and reaction kinetics. PMID:16343755

Andreozzi, R; Caprio, V; Di Somma, I; Sanchirico, R

2006-06-30

391

Dietary Eicosapentaenoic Acid and Docosahexaenoic Acid Are More Effective than Alpha-Linolenic Acid in Improving Insulin Sensitivity in Rats  

Microsoft Academic Search

In the present study, we investigated whether long-term administration of high dose of ?-linolenic acid (ALA) is able to mimic the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) or a mixture of both with respect to insulin sensitivity in male Wistar rats. Furthermore, we intended to test whether these n–3 polyunsaturated fatty acids reveal differential effects on glucose

Gaby Andersen; Kerstin Harnack; Helmut F. Erbersdobler; Veronika Somoza

2008-01-01

392

Gallic Acid, Ellagic Acid and Pyrogallol Reaction with Metallic Iron  

NASA Astrophysics Data System (ADS)

The reaction between gallic acid, ellagic acid and pyrogallol with metallic iron was studied using infrared and Mössbauer spectroscopy. Most hydrolysable tannins with interesting anticorrosive or inhibition properties are structurally related to these compounds, thus they may be used as models for the study of hydrolysable tannins and related polyphenols. The interaction was followed up to 3 months. Results indicated two different behaviors. At polyphenol concentrations higher than 1% iron converts to sparingly soluble and amorphous ferric (and ferrous) polyphenolate complexes. At lower concentrations (0.1%), the hydrolysis reactions are dominant, resulting in the formation of oxyhydroxides, which can be further reduced to compounds like magnetite by the polyphenols.

Jaén, J. A.; González, L.; Vargas, A.; Olave, G.

2003-06-01

393

Biopharmaceutical aspects of tolfenamic acid.  

PubMed

The pharmacokinetics of tolfenamic acid is well described by a two-compartment model with relatively short half-lives (T/2 beta 1-2 hours) and tolfenamic acid is highly protein-bound with small volumes of distribution. It is cleared relatively fast (150-200 ml/min), mainly by hepatic metabolism and the metabolites are renally cleared as glucuronic acid conjugates. The peroral absorption is good and the peroral bioavailability is about 75%, as first pass metabolism accounts for about 20%. Tolfenamic acid shows linear pharmacokinetics and during multiple dosage regimen, i.e. thrice daily, no accumulation beyond the second dose is observed. The bioavailability in dependence of age and disease has been studied and only in the case of severe liver or kidney impairment, a change in dosage regimen seems warranted. The development of different formulations will be outlined, mainly on rectal delivery, on sustained release and rapid release oral formulations, on topical ointment, and on parenteral delivery. The problems with tolfenamic acid in pharmaceutical formulation caused mainly by poor solubility will be discussed. Formulations ready for the market now or very soon are Clotam capsules (tablets). Clotam retard tablets, Clotam suppositories, and Clotam oral suspension, whereas rapid tablets, topical ointments, and parenteral formulations need further development to be ready for marketing in the years to come. PMID:7816776

Pedersen, S B

1994-01-01

394

Identifying acid salts of magnesium  

SciTech Connect

In preliminary work they found that significant quantities of certain nitrogen oxides and of sulfuric acid were absorbed by lower hydrates of magnesium sulfate. It appeared that acid salts were being formed but the known chemistry of group IIA (group 2) sulfates and acid sulfates which was worked out many years ago did not provide an explanation of their observations. They developed a new technique for delineating the solidus boundary of ternary mixtures using friability tests and applied it to the systems of interest. Magnesium acid salt hydrates with compositions on the solidus boundary could be readily identified. X-ray powder patterns confirmed the existence of two previously unknown ternary compounds, Mg/sub 2/(HSO/sub 4/)/sub 2/SO/sub 4/ x 4H/sub 2/O and Mg(HSO/sub 4/)/sub 2/ x H/sub 2/SO/sub 4/ x 3H/sub 2/O. Mixed acid sulfate-nitrate-hydrates could be detected but fuming at room temperatures interfered with quantitative determinations of the solidus boundary and X-ray measurements.

Plumb, R.; Thivierge, R.F. Jr.; Xu, W.W.

1987-11-05

395

Original article Concentrations of catecholamines, ascorbic acid,  

E-print Network

Original article Concentrations of catecholamines, ascorbic acid, progesterone and oxytocin progesterone, oxytocin (OT), dopamine (DA), noradrenaline (NA) and ascorbic acid, these compounds were measured-cold metaphosphoric acid (for ascorbic acid). There were no signi- ficant differences in the measured parameters

Paris-Sud XI, Université de

396

Original article Antimicrobial activity of fatty acids  

E-print Network

. For example, while myr- istic acid (14:0) was only slightly active (10 mm inhibition zone), myristoleic acidOriginal article Antimicrobial activity of fatty acids against Bacillus larvae, the causative agent and unsaturated free fatty acids were tested for their antibiotic activ- ity against Bacillus larvae

Paris-Sud XI, Université de

397

Acid Rain: Effects on Fish and Wildlife.  

National Technical Information Service (NTIS)

This report discusses: What is acid rain; What causes acid rain; Where do sulfur and nitrogen oxides originate; What areas in the U.S. are susceptible to acid rain; Are there early warning signals of acidification to aquatic resources; How does acid rain ...

K. S. Mayer, E. P. Multer, R. K. Schreiber

1984-01-01

398

Acid sorption regeneration process using carbon dioxide  

DOEpatents

Carboxylic acids are sorbed from aqueous feedstocks onto a solid adsorbent in the presence of carbon dioxide under pressure. The acids are freed from the sorbent phase by a suitable regeneration method, one of which is treating them with an organic alkylamine solution thus forming an alkylamine-carboxylic acid complex which thermally decomposes to the desired carboxylic acid and the alkylamine.

King, C. Judson (Kensington, CA); Husson, Scott M. (Anderson, SC)

2001-01-01

399

Extraction of carboxylic acids by amine extractants  

Microsoft Academic Search

This work examines the chemistry of solvent extraction by long-chain amines for recovery of carboxylic acids from dilute aqueous solution. Long-chain amines act as complexing agents with the acid, which facilitates distribution of the acid into the organic phase. The complexation is reversible, allowing for recovery of the acid from the organic phase and regeneration of the extractant. Batch extraction

Janet Ayako Tamada; C. J. King

1989-01-01

400

21 CFR 189.155 - Monochloroacetic acid.  

...2014-04-01 2014-04-01 false Monochloroacetic acid. 189.155 Section 189.155 Food and Drugs...Use as Human Food § 189.155 Monochloroacetic acid. (a) Monochloroacetic acid is the chemical chloroacetic acid, C2 H3...

2014-04-01

401

21 CFR 184.1021 - Benzoic acid.  

... 2014-04-01 2014-04-01 false Benzoic acid. 184.1021 Section 184.1021 Food and Drugs...Substances Affirmed as GRAS § 184.1021 Benzoic acid. (a) Benzoic acid is the chemical benzenecarboxylic acid (C7 H6...

2014-04-01

402

8, 687725, 2008 Effect of fatty acids  

E-print Network

, high contents of humic acids in the aerosol, a struc- turally inhomogeneous, quite water solubleACPD 8, 687�725, 2008 Effect of fatty acids on HNO3 uptake to aqueous aerosol K. Stemmler et al Chemistry and Physics Discussions The effect of fatty acid surfactants on the uptake of nitric acid

Paris-Sud XI, Université de

403

Salicylic acid-independent plant defence pathways  

Microsoft Academic Search

Salicylic acid is an important signalling molecule involved in both locally and systemically induced disease resistance responses. Recent advances in our understanding of plant defence signalling have revealed that plants employ a network of signal transduction pathways, some of which are independent of salicylic acid. Evidence is emerging that jasmonic acid and ethylene play key roles in these salicylic acid-independent

Corné M. J Pieterse; Leendert C van Loon

1999-01-01

404

Enhancers of iron absorption: ascorbic acid and other organic acids.  

PubMed

Ascorbic acid (AA), with its reducing and chelating properties, is the most efficient enhancer of non-heme iron absorption when its stability in the food vehicle is ensured. The number of studies investigating the effect of AA on ferrous sulfate absorption far outweighs that of other iron fortificants. The promotion of iron absorption in the presence of AA is more pronounced in meals containing inhibitors of iron absorption. Meals containing low to medium levels of inhibitors require the addition of AA at a molar ratio of 2:1 (e.g., 20 mg AA: 3 mg iron). To promote absorption in the presence of high levels of inhibitors, AA needs to be added at a molar ratio in excess of 4:1, which may be impractical. The effectiveness of AA in promoting absorption from less soluble compounds, such as ferrous fumarate and elemental iron, requires further investigation. The instability of AA during food processing, storage, and cooking, and the possibility of unwanted sensory changes limits the number of suitable food vehicles for AA, whether used as vitamin fortificant or as an iron enhancer. Suitable vehicles include dry-blended foods, such as complementary, precooked cereal-based infant foods, powdered milk, and other dry beverage products made for reconstitution that are packaged, stored, and prepared in a way that maximizes retention of this vitamin. The consumption of natural sources of Vitamin C (fruits and vegetables) with iron-fortified dry blended foods is also recommended. Encapsulation can mitigate some of the AA losses during processing and storage, but these interventions will also add cost. In addition, the bioavailability of encapsulated iron in the presence/absence of AA will need careful assessment in human clinical trials. The long-term effect of high AA intake on iron status may be less than predicted from single meal studies. The hypothesis that an overall increase of dietary AA intake, or fortification of some foods commonly consumed with the main meal with AA alone, may be as effective as the fortification of the same food vehicle with AA and iron, merits further investigation. This must involve the consideration of practicalities of implementation. To date, programs based on iron and AA fortification of infant formulas and cow's milk provide the strongest evidence for the efficacy of AA fortification. Present results suggest that the effect of organic acids, as measured by in vitro and in vivo methods, is dependent on the source of iron, the type and concentration of organic acid, pH, processing methods, and the food matrix. The iron absorption-enhancing effect of AA is more potent than that of other organic acids due to its ability to reduce ferric to ferrous iron. Based on the limited data available, other organic acids may only be effective at ratios of acid to iron in excess of 100 molar. This would translate into the minimum presence/addition of 1 g citric acid to a meal containing 3 mg iron. Further characterization of the effectiveness of various organic acids in promoting iron absorption is required, in particular with respect to the optimal molar ratio of organic acid to iron, and associated feasibility for food application purposes. The suggested amount of any organic acid required to produce a nutritional benefit will result in unwanted organoleptic changes in most foods, thus limiting its application to a small number of food vehicles (e.g., condiments, beverages). However, fermented foods that already contain high levels of organic acid may be suitable iron fortification vehicles. PMID:15743017

Teucher, Birgit; Olivares, Manuel; Cori, Héctor

2004-11-01

405

Acid deposition and forest decline  

SciTech Connect

The available evidence does not show a clear cause and effect relationship between acid deposition and forest decline and dieback in the US. The second of two articles examines soil and vegetation changes, summarizes the theories on spruce and fir dieback in Central Europe, and assesses the possible natural and manmade causes. The location, topography and other characteristics of the high-elevation forests of eastern North America cause them to be receptors of high levels of acid deposition and airborn trace metals. The authors find several possible pathways for acid deposition to contribute to spruce mortality, but none are supported by convincing evidence. However, there is evidence for the triggering effect of drought in a situation of multiple stresses. 55 references, 13 figures, 1 table.

Johnson, A.H.; Siccama, T.G.

1983-01-01

406

(International conference on acidic deposition)  

SciTech Connect

The traveler took the opportunity to participate in a mini-sabbatical at the Institute of Terrestrial Ecology (ITE) in Edinburgh, Scotland, as a part of planned travel to Glasgow, Scotland, to attend the International Conference on Acidic Precipitation. The purpose of the sabbatical was to provide quality time for study and interchange of ideas with scientists at ITE working on physiological effects of acidic deposition and to allocate significant time for writing and synthesizing of results of physiological studies from the National Forest Response Program's Spruce/Fir Research Cooperative. The study focused on the very significant cytological and physiological effects of calcium deficiency in trees, a response that appears to be amplified in spruce by acidic deposition.

McLaughlin, S.B. Jr.

1990-10-05

407

Identification of in Vivo Phosphorylation Sites and Their Functional Significance in the Sodium Iodide Symporter*  

E-print Network

activity is the basis for targeted radioiodide ablation of thyroid cancers. Although it has been shown or absent in patients with advanced thyroid cancer, consequently rendering radioiodide therapy ineffective (NIS)2 is an intrinsic membrane gly- coprotein most commonly studied in context with the thyroid gland

Tsai, Ming-Daw

408

297. Radiovirotherapy in Ovarian Cancer Using Recombinant Measles Expressing Sodium Iodide Symporter  

Microsoft Academic Search

We have shown that the MV-Edm, a vaccine strain of measles virus, is potently oncolytic for many types of tumor cells but causes minimal damage on normal cells. Phase I clinical trial in ovarian cancer using recombinant measles virus which express soluble CEA for non-invasive monitoring of the profiles of viral gene expression is on-going in our institution. We are

Kosei Hasegawa; Hooi-Tin Ong; David Dingli; Takafumi Nakamura; Stephen J. Russell; Kah Whye Peng

2005-01-01

409

The human sodium-iodine symporter (NIS) as a key for specific thymic iodine-131 uptake  

Microsoft Academic Search

or post-treatment 131I scan in patients with differentiated thyroid cancer is indispensable if unnecessary therapeutic procedures are to be avoided. False-positive findings in the chest may be attributable either to body secretions and pathological transudates or to inflammatory processes, neoplasms of non-thyroidal origin or ectopic thyroid tissue [1?10]. Thymic uptake of 131I is known to be one condition which can

J. Meller; W. Becker

2000-01-01

410

Potassium-proton symport in Neurospora : kinetic control by pH and membrane potential  

Microsoft Academic Search

Summary Active transport of potassium in K+-starvedNeurospora was previously shown to resemble closely potassium uptake in yeast,Chlorella, and higher plants, for which K+ pumps or K+\\/H+-ATPases had been proposed. ForNeurospora, however, potassium-proton cotransport was demonstrated to operate, with a coupling ratio of 1 H+ to 1 K+ taken inward so that K+, but not H+, moves against its electrochemical gradient

Michael R. Blatt; Alonso Rodriguez-Navarro; Clifford L. Slayman

1987-01-01

411

Hydroxamic Acids in Asymmetric Synthesis  

PubMed Central

Metal-catalyzed stereoselective reactions are a central theme in organic chemistry research. In these reactions, the stereoselection is achieved predominantly by introducing chiral ligands at the metal catalyst’s center. For decades, researchers have sought better chiral ligands for asymmetric catalysis and have made great progress. Nevertheless, to achieve optimal stereoselectivity and to catalyze new reactions, new chiral ligands are needed. Due to their high metal affinity, hydroxamic acids play major roles across a broad spectrum of fields from biochemistry to metal extraction. Dr. K. Barry Sharpless first revealed their potential as chiral ligands for asymmetric synthesis in 1977: He published the chiral vanadium-hydroxamic-acid-catalyzed, enantioselective epoxidation of allylic alcohols before his discovery of Sharpless Asymmetric Epoxidation, which uses titanium-tartrate complex as the chiral reagent. However, researchers have reported few highly enantioselective reactions using metal-hydroxamic acid as catalysts since then. This Account summarizes our research on metal-catalyzed asymmetric epoxidation using hydroxamic acids as chiral ligands. We designed and synthesized a series of new hydroxamic acids, most notably the C2-symmetric bis-hydroxamic acid (BHA) family. V-BHA-catalyzed epoxidation of allylic and homoallylic alcohols achieved higher activity and stereoselectivity than Sharpless Asymmetric Epoxidation in many cases. Changing the metal species led to a series of unprecedented asymmetric epoxidation reactions, such as (i) single olefins and sulfides with Mo-BHA, (ii) homoallylic and bishomoallylic alcohols with Zr- and Hf-BHA, and (iii) N-alkenyl sulfonamides and N-sulfonyl imines with Hf-BHA. These reactions produce uniquely functionalized chiral epoxides with good yields and enantioselectivities. PMID:23157425

Li, Zhi; Yamamoto, Hisashi

2012-01-01

412

Molecular Structure of Oleic acid  

NSDL National Science Digital Library

A mono-unsaturated fatty acid, oleic acid is a component of almost all natural fats. It is obtained from any of various vegetable and animal oils and fats, particularly the seeds of castor, sunflower, safflower, parsley, soybean, flax, perilla, and celery. A colorless or yellow-to-red oily liquid with a lard-like odor, it solidifies to a crystalline mass at four degrees Celsius. When exposed to air it oxidizes and acquires a yellow to brown color and rancid odor; for this reason it should be kept sealed in a container and away from sunlight. It is almost completely insoluble in water but is soluble in alcohol, benzene chloroform, ether, and fixed and volatile oils. Although oleic acid has a low level of toxicity when absorbed orally, it is mildly irritating to the skin and mucous membranes. It also is combustible. Oleic acid is used as a soap base and in the production of food-grade additives, ointments, cosmetics, fragrance products, polishing compounds, surface coatings, and manufacturing driers. It is used for waterproofing textiles and for thickening lubricating oils. It also is used as a solvent in the manufacture of pharmaceuticals. It contributes to the flavor of foods and is found in sweet cider apples. One of the "good" or unsaturated fatty acids, oleic acid has proven helpful to cell and heart function. It has shown anti-inflammatory effects in the body and has been used to treat arthritis, asthma, allergies, and skin conditions. Its inclusion in the diet has improved cases of diabetes, depression, menopausal problems, obesity, memory and learning disabilities, eye problems, and digestive disorders. It is considered to lower the incidence of cancer (as an antioxidant), multiple sclerosis, and lupus as well.

2003-05-08

413

New Insights into Bile Acid Malabsorption  

Microsoft Academic Search

Bile acid malabsorption occurs when there is impaired absorption of bile acids in the terminal ileum, so interrupting the\\u000a normal enterohepatic circulation. The excess bile acids in the colon cause diarrhea, and treatment with bile acid sequestrants\\u000a is beneficial. The condition can be diagnosed with difficulty by measuring fecal bile acids, or more easily by retention of\\u000a selenohomocholyltaurine (SeHCAT), where

Ian Johnston; Jonathan Nolan; Sanjeev S. Pattni; Julian R. F. Walters

414

Inhibitors of Fatty Acid Synthesis and Elongation  

NSDL National Science Digital Library

Fatty acid synthesis and fatty acid elongation are two parts of a critically important pathway in plants. The endproducts are essential components of cell membranes, waxes, and suberin. Two chemical families of herbicide (groups that share similar chemical structures) inhibit fatty acid synthesis, while fatty acid elongation is inhibited by two other families. This lesson will provide an overview of fatty acid synthesis and elongation, and explain where herbicides inhibit the pathway. Mechanisms of resistance to these herbicides will be described.

415

Structure of beta-Boswellinic Acid  

Microsoft Academic Search

THE investigations of Ruzicka, and of Winterstein and their co-workers, have shown that the majority of the triterpene acids (hederagenin, gypsogenin, oleanolic acid, sia- and suma-resinolic acids) are in all probability theta-hydroxy-gamma : delta-unsaturated mono-basic acids, as indicated in the accompanying formula1. On the other hand, (beta-boswellinic acid, C29H46(OH)COOH, one of the principal triterpene constituents of frankincense, evidently possesses a

J. C. E. Simpson

1937-01-01

416

Recovery of Carboxylic Acids from Fermentation Broth via Acid Springing  

E-print Network

ix LIST OF FIGURES FIGURE Page 1-1 Oil consumption of the United States and other countries ......................... 1 1-2... MixAlco process overview ......................................................................... 5 1-3 Acid springing process .............................................................................. 7 2-1 Projected dimensions of 0...

Dong, Jipeng

2010-01-14

417

Acid soil and acid rain, 2nd edition  

Microsoft Academic Search

This book examines the basic chemical processes involved in acidification in order to better assess their long-term effects on the status of soils, the health of plants and other living species that depend on them. It also discusses acidity, pH and protons their significance in bioenergetics and the consequent role of autotrophic organisms in acidifying ecosystems. This edition incorporates and

1992-01-01

418

Amino Acid-Derived Enaminones  

PubMed Central

A new reaction for the preparation of enaminones has been discovered. This method employs ?-amino acids as starting materials to allow diversification as well as incorporation of chirality. The ?-amino acids, once converted to ynones, are readily cyclized to the desired six membered enaminone via a two-step, one pot protocol. Although disguised as a 6-endo-dig cyclization, the reagents employed in the transformation play a direct role in bond making and bond breaking, thus changing the mode of addition. PMID:16819843

Turunen, Brandon J.; Georg, Gunda I.

2008-01-01

419

Molecular Structure of (+-)-Malic acid  

NSDL National Science Digital Library

Malate, or Malic acid, is found readily in fruits and in the leaves of C4 and CAM plants as storage for carbon dioxide (CO2). In C4 plants, malate is an intermediate during photosynthesis, while in CAM plants it is used to store the CO2 until the stomata are closed at night. It is also key to the production of ATP by the mitochondria. Oxaloacetate is reduced to malate, which is then transported into the mitochondria. Malic acid is frequently used for flavoring of an assortment of products. It is also used as a drug to assist ATP formation, ensuring proper muscle function at even low oxygen levels.

2003-05-08

420

Benefits of acid rain controls  

SciTech Connect

The acid rain debate has been distorted by a mistaken political paradigm. This paradigm holds that acid rain controls will benefit only a few lakes and streams, mostly in the Adirondack Mountains in northeastern New York State. It holds that the costs of a control program will fall on the Midwest but that none of the benefits will occur there since no sensitive lakes and streams are found in that area. The author discussed this problem and pointed out that sulfur dioxide was responsible for several types of pollution damage and that all the states would benefit from the reduction of sulfur dioxide emissions.

Hawkins, D.G.

1984-04-01

421

Bipolar lead acid battery development  

NASA Technical Reports Server (NTRS)

A modular bipolar battery configuration is under development at Johnson Control, Inc. (JCI) and the Jet Propulsion Laboratory (JPL). The battery design, incorporating proven lead acid electrochemistry, yields a rechargeable, high-power source that is light weight and compact. This configuration offers advantages in power capability, weight, and volume over conventional monopolar batteries and other battery chemistries. The lead acid bipolar battery operates in a sealed, maintenance-free mode allowing for maximum application flexibility. It is ideal for high-voltage and high-power applications.

Eskra, Michael; Vidas, Robin; Miles, Ronald; Halpert, Gerald; Attia, Alan; Perrone, David

1991-01-01

422

Selective Catalysis of Lactic Acid to Produce Commodity Chemicals  

Microsoft Academic Search

Owning to its biobased organic acid, low cost and multiple reactive functionalities as it contains both one carboxylic acid group and hydroxyl group, lactic acid has been described as a commodity chemical sleeping giant. In this review, the conversion of lactic acid to other important commodity chemicals, such as, poly L?lactic acid, acrylic acid, 2, 3?pentanedione, pyruvic acid, propanoic acid,

Yongxian Fan; Chunhui Zhou; Xiaohong Zhu

2009-01-01

423

Comparative fatty acid composition of four Sargassum species (Fucales, Phaeophyta)  

NASA Astrophysics Data System (ADS)

Fatty acid composition of four Sargassum species from Qingdao and Shidao, Shandong Province was investigated. 16:0 (palmitic acid) was the major saturated fatty acid. C18 and C20 were the main polyunsaturated fatty acids (PUFAs). Arachidonic acid and eicosapentaenoic acid predominated among polyenoic acids in all the algal species examined, except for Sargassum sp. which had low concentration of eicosapentaenoic acid.

Wu, Xiang-Chun; Lu, Bao-Ren; Tseng, C. K.

1995-12-01

424

Studies on technetium and some carboxylic and hydroxamic acids  

Microsoft Academic Search

Interactions between technetium and salicylic acid, oxalic acid, gentisic acid, dipicolinic acid, pyridine-2,5-dicarboxylic acid, salicylhydroxamic acid, dipicolindihydroxamic acid and 5-methoxycarbonyl-2-pyridinehydroxamic acid are described. The complexation reactions have been investigated (pH, , stability, stoichiometry) and the results obtained have been comparatively evaluated.

F. Grases; G. Far; J. G. March

1985-01-01

425

Citric Acid Passivation of Stainless Steel  

NASA Technical Reports Server (NTRS)

Passivation is a process for cleaning and providing corrosion protection for stainless steel. Currently, on Kennedy Space Center (KSC), only parts passivated with nitric acid are acceptable for use. KSC disposes of approximately 125gal of concentrated nitric acid per year, and receives many parts from vendors who must also dispose of used nitric acid. Unfortunately, nitric acid presents health and environmental hazards. As a result, several recent industry studies have examined citric acid as an alternative. Implementing a citric acid-based passivation procedure would improve the health and environmental safety aspects of passivation process. However although there is a lack of published studies that conclusively prove citric acid is a technically sound passivation agent. In 2007, NASA's KSC Materials Advisory Working Group requested the evaluation of citric acid in place of nitric acid for passivation of parts at KSC. United Space Alliance Materials & Processes engineers have developed a three-phase test plan to evaluate citric acid as an alternative to nitric acid on three stainless steels commonly used at KSC: UNS S30400, S41000, and S17400. Phases 1 and 2 will produce an optimized citric acid treatment based on results from atmospheric exposure at NASA's Beach Corrosion Facility. Phase 3 will compare the optimized solution(s) with nitric acid treatments. If the results indicate that citric acid passivates as well or better than nitric acid, NASA intends to approve this method for parts used at the Kennedy Space Center.

Yasensky, David; Reali, John; Larson, Chris; Carl, Chad

2009-01-01

426

Amino Acid Analyses of Acid Hydrolysates in Desert Varnish  

NASA Technical Reports Server (NTRS)

There has long been a debate as to whether rock varnish deposits are microbially mediated or are deposited by inorganic processes. Varnished rocks are found throughout the world primarily in arid and semi-arid regions. The varnish coats are typically up to 200 microns thick and are composed of clays and alternating layers enriched in manganese and iron oxides. The individual layers range in thickness from 1 micron to greater than 10 microns and may continue laterally for more than a 100 microns. Overlapping botryoidal structures are visible in thin section and scanning electron micrographs. The coatings also include small amounts of organic mater and detrital grains. Amino-acid hydrolysates offer a means of assessing the organic composition of rock varnish collected from the Sonoran Desert, near Phoenix, AZ. Chromatographic analyses of hydrolysates from powdered samples of rock varnish suggest that the interior of rock varnish is relatively enriched in amino acids and specifically in d-alanine and glutamic acid. Peptidoglycan (murein) is the main structural component of gram-positive bacterial cell walls. The d-enantiomer of alanine and glutamic acid are specific to peptidoglycan and are consequently an indicator for the presence of bacteria. D-alanine is also found in teichoic acid which is only found in gram-positive bacteria. Several researchers have cultured bacteria from the surface of rock varnish and most have been gram-positive, suggesting that gram-positive bacteria are intimately associated with varnish coatings and may play a role in the formation of varnish coatings.

Perry, Randall S.; Staley, James T.; Dworkin, Jason P.; Engel, Mike

2001-01-01

427

Pakistan Vet. J., 24(3): 2004 EFFECTS OF ASCORBIC ACID AND ACETYLSALICYLIC ACID  

E-print Network

Pakistan Vet. J., 24(3): 2004 109 EFFECTS OF ASCORBIC ACID AND ACETYLSALICYLIC ACID SUPPLEMENTATION into 5 equal groups and kept under elevated temperature (93-97o F) to see the effect of ascorbic acid, thymus and spleen to body weight of the birds. Ascorbic acid and acetylsalicylic acid supplementation

Paris-Sud XI, Université de

428

Method for production of petroselinic acid and OMEGA12 hexadecanoic acid in transgenic plants  

DOEpatents

The present invention relates to a process for producing lipids containing the fatty acid petroselinic acid in plants. The production of petroselinic acid is accomplished by genetically transforming plants which do not normally accumulate petroselinic acid with a gene for a .omega.12 desaturase from another species which does normally accumulate petroselinic acid.

Ohlrogge, John B. (Okemos, MI); Cahoon, Edgar B. (Lansing, MI); Shanklin, John (Upton, NY); Somerville, Christopher R. (Okemos, MI)

1995-01-01

429

Acid deposition in Maryland: Implications of the results of the National Acid Precipitation Assessment Program  

SciTech Connect

Acid deposition, commonly referred to as 'acid rain,' is a major global environmental concern. Acid deposition has reportedly resulted in damage to aquatic, terrestrial, and physical resources and has potentially adverse effects on human health. A component of the Maryland acid deposition program is the preparation of an annual report that summarizes yearly activities and costs of ongoing acid deposition research and monitoring programs.

DeMuro, J.; Bowmann, M.; Ross, J.; Blundell, C.; Price, R.

1991-07-01

430

Method for production of petroselinic acid and OMEGA12 hexadecanoic acid in transgenic plants  

DOEpatents

The present invention relates to a process for producing lipids containing the fatty acid, petroselinic acid, in plants. The production of petroselinic acid is accomplished by genetically transforming plants which do not normally accumulate petroselinic acid with a gene for a {omega}12 desaturase from another species which does normally accumulate petroselinic acid. 19 figs.

Ohlrogge, J.B.; Cahoon, E.B.; Shanklin, J.; Somerville, C.R.

1995-07-04

431

Correlation between acetic acid resistance and characteristics of PQQ-dependent ADH in acetic acid bacteria  

Microsoft Academic Search

In this study, we compared the growth properties and molecular characteristics of pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase (ADH) among highly acetic acid-resistant strains of acetic acid bacteria. Ga. europaeus exhibited the highest resistance to acetic acid (10%), whereas Ga. intermedius and Acetobacter pasteurianus resisted up to 6% of acetic acid. In media with different concentrations of acetic acid, the maximal

Janja Trcek; Hirohide Toyama; Jerzy Czuba; Anna Misiewicz; Kazunobu Matsushita

2006-01-01

432

in amino-acid concentration enhanced amino-acid and glucose utilization for lipogenesis, with no  

E-print Network

in amino-acid concentration enhanced amino- acid and glucose utilization for lipogenesis more strongly amino-acid and glucose incorporation into cellular lipids, the glu- cose incorporation showed a synergistic effect between insulin and amino acids for up to 1.59 g/I amino acid in the medium

Boyer, Edmond

433

Process for the reclamation of battery acid and fluid from expended lead-acid batteries  

Microsoft Academic Search

This patent describes a method for recycling contaminated sulfuric acid from lead acid batteries to reclaimed sulfuric acid fore reuse in the batteries by removing contaminating iron impurities. It comprises: diluting the contaminated sulfuric acid to a concentration between 150 and 230 grams per liter; filtering the sulfuric acid through a first filter means to remove solid impurities.

1990-01-01

434

21 CFR 172.350 - Fumaric acid and salts of fumaric acid.  

... 2014-04-01 2014-04-01 false Fumaric acid and salts of fumaric acid. 172.350 Section 172.350 Food and Drugs...and Nutritional Additives § 172.350 Fumaric acid and salts of fumaric acid. Fumaric acid...

2014-04-01

435

Effect of formic acid and benzoic acid esters on grass preservation  

E-print Network

alternatives for benzoic acid and propionic acid was the high prices of these components. The esters of benzoicEffect of formic acid and benzoic acid esters on grass preservation A Rauramaa A Tommila J Ltd, Espoo Reseach Centre, PO Box 44, 02271 Espoo, Finland Formic acid is known to improve silage

Paris-Sud XI, Université de

436

Influence of dietary essential fatty acid level on fatty acid composition in peripheral nerve and muscle  

E-print Network

fatty acids, in the presence of a very high linoleic acid level, the PUFA of the (n-6) series decreased of polyunsaturated fatty acids (Kishimoto et al., 1969). This observation may be related to the highly specializedInfluence of dietary essential fatty acid level on fatty acid composition in peripheral nerve

Paris-Sud XI, Université de

437

Effect of Acetic Acid on the Oxidation of Ascorbic Acid in Fruits and Vegetables  

Microsoft Academic Search

IT has been established by earlier investigators that acetic acid has a destructive effect on the ascorbic acid in raw cabbage. This effect is somewhat surprising, since the lower the pH in the medium, the more stable is the ascorbic acid and, therefore, one would expect the acetic acid to have a preservative effect on the ascorbic acid in cabbage.

F. Alm

1952-01-01

438

Gadolinium-Diethylenetriamine pentaacetic acid-poly(lactic-co-glycolic acid) microbubbles  

E-print Network

Gadolinium-Diethylenetriamine pentaacetic acid-poly(lactic-co- glycolic acid) microbubbles [Gd-Diethylenetriamine pentaacetic acid-poly(lactic-co-glycolic acid) microbubbles Abbreviated name: Gd-DTPA-PLGA, Gd-PLGA SynonymImagingandContrastAgentDatabase(MICAD) #12;drug and gene delivery (7). Ao et al. (8) used poly(lactic-co-glycolic acid) (PLGA

Levin, Judith G.

439

CHAPTER 13. ACID RAIN Acid rain was discovered in the 19th century by Robert Angus  

E-print Network

decline of fish populations in the lakes of southern Norway and traced the problem to acid rain. Similar to the precipitation acidity. Both are strong acids which dissociate quantitatively in water to release H+: (R5) (R6247 CHAPTER 13. ACID RAIN Acid rain was discovered in the 19th century by Robert Angus Smith

Jacob, Daniel J.

440

The Arabidopsis hrl1 mutation reveals novel overlapping roles for salicylic acid, jasmonic acid and ethylene  

E-print Network

The Arabidopsis hrl1 mutation reveals novel overlapping roles for salicylic acid, jasmonic acid molecules: salicylic acid (SA), jasmonic acid (JA) and ethylene (ET). The hrl1 (hypersensitive response defence. Salicylic acid (SA) is both essential and suf®cient to induce SAR because transgenic expression

Raina, Ramesh

441

Role of Salicylic Acid and Fatty Acid Desaturation Pathways in ssi2-Mediated Signaling1[W  

E-print Network

Role of Salicylic Acid and Fatty Acid Desaturation Pathways in ssi2-Mediated Signaling1[W] Pradeep for the regu- lation of salicylic acid (SA)- and jasmonic acid-mediated defense signaling in the plant, including the pathogenesis-related (PR) genes and the accumulation of salicylic acid (SA) in the inoculated

Kachroo, Pradeep

442

Vinyl Citrates from Citric Acid as New Monomers.  

National Technical Information Service (NTIS)

The synthesis of citric acid vinyl esters and its homo and copolymerization properties were studied. Citric acid trivinyl ester cannot be built up directly with citric acid. Acetyl anhydro citric acid obtained by acetylation of citric acid can be converte...

H. F. Muisers, F. Mietzsch

1983-01-01

443

Isolation, purification, and characterization of phenylpyruvate transaminating enzymes of Erwinia carotovora.  

PubMed

Enzymes of Erwinia carotovora that transaminate phenylpyruvate were isolated, purified, and characterized. Two aromatic aminotransferases (PAT1 and PAT2) and an aspartic aminotransferase (PAT3) were found. According to gel filtration, these enzymes have molecular weights of 76, 75, and 78 kDa. The enzymes consist of two identical subunits of molecular weights of 31.4, 31, and 36.5 kDa, respectively. The isoelectric points of PAT1, PAT2, and PAT3 were determined as 3.6, 3.9, and 4.7, respectively. The enzyme preparations considerably differ in substrate specificity. All three of the enzymes productively interacted with the following amino acids: L-aspartic acid, L-leucine (except PAT3), L-isoleucine (except PAT3), L-serine, L-methionine, L-cysteine, L-phenylalanine, L-tyrosine, and L-tryptophane. The aromatic aminotransferases display higher specificity to the aromatic amino acids and the leucine-isoleucine pair, whereas the aspartic aminotransferase displays higher specificity to L-aspartic acid and relatively low specificity to the aromatic amino acids. The aspartic aminotransferase does not use L-leucine or L-isoleucine as a substrate. PAT1, PAT2, and PAT3 show the highest activity at pH 8.9 and at 48, 53, and 58°C, respectively. PMID:22339639

Paloyan, A M; Hambardzumyan, A A; Halebyan, Gh P

2012-01-01

444

Process for forming sulfuric acid  

DOEpatents

An improved electrode is disclosed for the anode in a sulfur cycle hydrogen generation process where sulfur dioxie is oxidized to form sulfuric acid at the anode. The active compound in the electrode is palladium, palladium oxide, an alloy of palladium, or a mixture thereof. The active compound may be deposited on a porous, stable, conductive substrate.

Lu, Wen-Tong P. (Upper St. Clair, PA)

1981-01-01

445

Acid rain: Rhetoric and reality  

Microsoft Academic Search

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

1987-01-01

446

Acid Rain: A Global Perspective.  

ERIC Educational Resources Information Center

Analyzes the nature, extent, consequences, and sources of problems associated with acid precipitation. Explains the dilemma in specific countries with an emphasis on Eurasia, India, and the Artic. Discusses control options and international efforts to abate acidification in the environment. (ML)

Baldwin, John H.

1985-01-01

447

Boric Acid in Kjeldahl Analysis  

ERIC Educational Resources Information Center

The use of boric acid in the Kjeldahl determination of nitrogen is a variant of the original method widely applied in many laboratories all over the world. Its use is recommended by control organizations such as ISO, IDF, and EPA because it yields reliable and accurate results. However, the chemical principles the method is based on are not…

Cruz, Gregorio

2013-01-01

448

Acid Rain 2000±1000  

Microsoft Academic Search

This essay will be not so much concerned with temporal changes in acid rain as the intellectual thinking that has surrounded it. The span of this interest will extend from the historic past to an imagined future, in an account that will look at the origins of ideas and potential futures within a number of themes rather attempt a linear

P. Brimblecombe

2001-01-01

449

The Challenge of Acid Rain  

Microsoft Academic Search

Acid rain's effects in soil and water leave no doubt about the need to control its causes. The main culprits are sulfur dioxide and nitrogen oxides, mainly from automobiles and power plants. This paper explains the extent of the problem in the USA. This paper also discusses environmentally and economically attractive technologies for the control of these pollutants: atmospheric fluidized

Volker A. Mohnen

1988-01-01

450

Hydrogenation using hydrides and acid  

DOEpatents

A process for the non-catalytic hydrogenation of organic compounds, which contain at least one reducible functional group, which comprises reacting the organic compound, a hydride complex, preferably a transition metal hydride complex or an organosilane, and a strong acid in a liquid phase.

Bullock, R. Morris (Wading River, NY)

1990-10-30

451

Structure of the Nucleic Acids  

Microsoft Academic Search

WE have formulated a structure for the nucleic acids which is compatible with the main features of the X-ray diagram and with the general principles of molecular structure, and which accounts satisfactorily for some of the chemical properties of the substances. The structure involves three intertwined helical polynucleotide chains. Each chain, which is formed by phosphate di-ester groups and linking

Linus Pauling; Robert B. Corey

1953-01-01

452

Lactic acid fermented vegetable juices  

Microsoft Academic Search

Fermented foods are food substrates that are invaded or overgrown by edible microorganisms whose en- zymes, particularly amylases, proteases and lipases, hy- drolyse polysaccharides, proteins and lipids to non-toxic products with flavours, aromas and textures pleasant and attractive to the human consumer (STEINKRAUS 1997). The lactic acid fermentation of vegetable products, applied as a preservation method for the production of

J. KAROVI?OVÁ; Z. KOHAJDOVÁ

453

Toxicological Characterization of Phthalic Acid  

PubMed Central

There has been growing concern about the toxicity of phthalate esters. Phthalate esters are being used widely for the production of perfume, nail varnish, hairsprays and other personal/cosmetic uses. Recently, exposure to phthalates has been assessed by analyzing urine for their metabolites. The parent phthalate is rapidly metabolized to its monoester (the active metabolite) and also glucuronidated, then excreted. The objective of this study is to evaluate the toxicity of phthalic acid (PA), which is the final common metabolic form of phthalic acid esters (PAEs). The individual PA isomers are extensively employed in the synthesis of synthetic agents, for example isophthalic acid (IPA), and terephthalic acid (TPA), which have very broad applications in the preparation of phthalate ester plasticizers and components of polyester fiber, film and fabricated items. There is a broad potential for exposure by industrial workers during the manufacturing process and by the general public (via vehicle exhausts, consumer products, etc). This review suggests that PA shows in vitro and in vivo toxicity (mutagenicity, developmental toxicity, reproductive toxicity, etc.). In addition, PA seems to be a useful biomarker for multiple exposure to PAEs in humans. PMID:24278572

Bang, Du Yeon; Lee, In Kyung

2011-01-01

454

Biopreservation by lactic acid bacteria  

Microsoft Academic Search

Biopreservation refers to extended storage life and enhanced safety of foods using the natural microflora and (or) their antibacterial products. Lactic acid bacteria have a major potential for use in biopreservation because they are safe to consume and during storage they naturally dominate the microflora of many foods. In milk, brined vegetables, many cereal products and meats with added carbohydrate,

Michael E. Stiles

1996-01-01

455

Applications of peptide nucleic acids  

Microsoft Academic Search

Several exciting new developments in the applications of the DNA mimic peptide nucleic acid (PNA) have been published recently. A possible breakthrough may have come in efforts to develop PNA into gene therapeutic drugs. In eukaryotic systems, antisense activity of PNAs (as peptide conjugates) has been reported in nerve cells and even in rats upon injection into the brain, and

Peter E Nielsen

1999-01-01

456

Nucleic Acids Molecular Biology Tools  

E-print Network

Biology and Genomics #12;Nucleic Acids Proteins Molecular Biology Tools Polymerase Chain Reaction (PCR The Central Dogma Key Enzymes: DNA Polymerase; RNA Polymerase; Ribosome; Reverse transcriptase Exercise of a DNA template into an RNA. Transcriptome: All mRNA in a cell Promoter In Prokaryotes: RNA polymerase

Qiu, Weigang

457

Microwave spectrum of salicylic acid  

NASA Astrophysics Data System (ADS)

The rotational spectra of salicylic acid and of three OD deuterated species have been investigated by free jet millimiter-wave absorption spectroscopy. Only lines of the most stable conformer, the one with an intramolecular hydrogen bond between the phenolic hydrogen and the carbonyl oxygen, have been observed. The positions of the phenolic and carboxylic hydrogens have been precisely derived.

Evangelisti, Luca; Tang, Shouyuan; Velino, Biagio; Caminati, Walther

2009-03-01

458

Sulphur, sulphur dioxide, sulphuric acid  

SciTech Connect

This book provides sizeable bibliographies of literature references accompanying each section. It also provides an appendix containing recent statistical data on sulphur and sulphuric acid production, consumption, trade and prices. Ninety-five detailed diagrams and fourty-eight high-quality photographs are also provided.