Search Results
Results 401 - 450 of 2421
< 4 5 6 7 8 9 10 11 12 13 14 >
Leyser Ottoline - - 2005
The plant hormone auxin, synthesised in the shoot apex, moves down the stem and inhibits lateral branching. Auxin does not travel upward into the branches, so it must act indirectly; for example, through a second messenger. However, recent work on auxin transport suggests a possible additional mechanism whereby auxin transport ...
Böhmer Christoph - - 2005
The mechanism of the mouse (m)B0AT1 (slc6a19) transporter was studied in detail using two electrode voltage-clamp techniques and tracer studies in the Xenopus oocyte expression system. All neutral amino acids induced inward currents at physiological potentials, but large neutral non-aromatic amino acids were the preferred substrates of mB0AT1. Substrates were ...
Konishi Yutaka - - 2005
The absorption characteristics of artepillin C (AC), an active ingredient of Brazilian propolis, were examined by measuring permeation across Caco-2 cell monolayers. The permeation rate in the basolateral-to-apical direction, J(bl-->ap), in the presence of proton gradient was 0.14 nmol/min/mg protein, whereas J(bl-->ap) in the absence of proton gradient was 1.14 ...
Bröer Angelika - - 2006
Recent success in the molecular cloning and identification of apical neutral amino acid transporters has shed a new light on inherited neutral amino acidurias, such as Hartnup disorder and Iminoglycinuria. Hartnup disorder is caused by mutations in the neutral amino acid transporter B(0) AT1 (SLC6A19). The transporter is found in ...
Weijers Dolf - - 2005
Molecular mechanisms of pattern formation in the plant embryo are not well understood. Recent molecular and cellular studies, in conjunction with earlier microsurgical, physiological, and genetic work, are now starting to define the outlines of a model where gradients of the signaling molecule auxin play a central role in embryo ...
Ban Nobuhiro - - 2005
The A subclass of the ABC (ATP-binding cassette) transporter superfamily has a structural feature that distinguishes it from other ABC transporters, and is proposed to be involved in the transmembrane transport of endogenous lipids. Here we have cloned mouse and rat full-length cDNAs of ABCA17, a novel ABC transporter belonging ...
Mizuarai Shinji - - 2005
Mitochondrial solute carrier family 25 member 10 (Slc25a10) transports dicarboxylates such as malate or succinate across the mitochondrial inner membrane. Although fatty acid synthesis in adipose tissue or the liver is initiated by citrate transport in exchange for malate across the mitochondrial membrane, the transporter responsible for supplying malate during ...
Ezquerro-Sáenz C - - 2006
The N-acetyl-D-galactosamine (GalNAc) transport system of Escherichia coli K92 was studied when the bacterium was grown in a chemically defined medium containing GalNAc as a carbon source. Kinetic measurements were carried out in vivo at 37 degrees C in 25 mM phosphate buffer, pH 7.0. Under these conditions, the uptake ...
Yamazaki M - - 2005
The effects of different fibric acid derivatives (bezafibrate, clofibrate, clofibric acid, fenofibrate, fenofibric acid and gemfibrozil) on human organic anion transporting-polypeptide 1B1 (OATP2, OATP-C, SLC21A6), multidrug resistance protein 2 (MRP2/ABCC2) and MDR1-type P-glycoprotein (P-gp/ABCB1) were examined in vitro. Cyclosporin A (a known inhibitor of OATP1B1 and P-gp), MK-571 (a known ...
Korithoski Bryan - - 2005
Streptococcus mutans, a normal inhabitant of dental plaque, is considered a primary etiological agent of dental caries. Two virulence determinants of S. mutans are its acidogenicity and aciduricity (the ability to produce acid and the ability to survive and grow at low pH, respectively). Citric acid is ubiquitous in nature; ...
Bjerkenstedt Lars - - 2006
Several mechanisms have been suggested to account for altered dopaminergic neurotransmission in schizophrenia. The brain is the only organ for which amino-acid transport is limited and competition for transport over the blood-brain barrier (BBB) occurs at physiological plasma concentrations. One line of research suggests that patients with schizophrenia have altered ...
Ludwig-Müller Jutta - - 2005
Root induction by auxins is still not well understood at the molecular level. In this study a system has been devised which distinguishes between the two active auxins indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA). IBA, but not IAA, efficiently induced adventitious rooting in Arabidopsis stem segments at a concentration ...
Bahn Andrew - - 2005
Tryptophan metabolites such as kynurenate (KYNA), xanthurenate (XA), and quinolinate are considered to have an important impact on many physiological processes, especially brain function. Many of these metabolites are secreted with the urine. Because organic anion transporters (OATs) facilitate the renal secretion of weak organic acids, we investigated whether the ...
Carroll F Ivy - - 2005
3alpha-(substituted phenyl)nortropane-2beta-carboxylic acid methyl esters (8a-h) showed high affinity for the norepinephrine transporter (NET). The most potent and selective compound was 3alpha-(3-fluoro-4-methylphenyl)nortropane-2beta-carboxylic acid methyl ester (8d), with a Ki of 0.43 nM at the NET and 21- and 55-fold selectivity relative to binding at the dopamine and serotonin transporters. The ...
Canepa Gaspar E - - 2005
Aspartate is one of the compounds that induce the differentiation process of the non-infective epimastigote stage to the infective trypomastigote stage of the protozoan parasite Trypanosoma cruzi. l-aspartate is transported by both epimastigote and trypomastigote cells at the same rate, about 3.4 pmolmin(-1) per 10(7) cells. Aspartate transport is only ...
Awad W A - - 2005
Most amino acids are cotransported with sodium. Deoxynivalenol (DON) decreases glucose absorption in the chicken small intestine in vivo and in vitro, and this effect is apparently mediated by the inhibition of the sodium D-glucose cotransporter. DON could selectively modulate the activities of other intestinal transporters. In order to assess ...
García-Amado M A - - 2005
The mechanisms involved in D-glucose and amino acid transport in the intestine of birds are still not clear. In chickens, D-glucose and amino acid absorption occurs via carrier-mediated transport, but in wild birds a passive paracellular mechanism seems to be the predominant pathway. The purpose of this work was to ...
Macpherson Neil - - 2005
The food spoilage yeasts Zygosaccharomyces bailii and Saccharomyces cerevisiae have been proposed to resist weak-acid preservative stress by different means; Z. bailii by limiting influx of preservative combined with its catabolism, S. cerevisiae by active extrusion of the preservative weak-acid anion and H(+). Measurement of H(+) extrusion by exponential-phase Z. ...
Sonders Mark S - - 2005
Plasma membrane neurotransmitter transporters for monoamines, GABA, glycine and excitatory amino acids are homologous to two sizable families of bacterial amino acid transporters. Recently, a high resolution structure was determined for a thermophilic glutamate transporter. Also, a bacterial tryptophan transporter related to the family of biogenic amine neurotransmitter transporters was ...
Neufeld Douglas S G - - 2005
We demonstrate the presence of an efficient, multispecific transport system for excretion of organic anions in the Malpighian tubules of the cricket Acheta domesticus using fluorescein (FL) as a model substrate. Malpighian tubules rapidly accumulated FL via a high affinity process (Km = 7.75 micromol l(-1)); uptake was completely eliminated ...
Paul Brian J BJ Department of Bacteriology, University of Wisconsin, 420 Henry Mall, Madison, WI 53706, - - 2005
Amino acid starvation in Escherichia coli results in a spectrum of changes in gene expression, including inhibition of rRNA and tRNA promoters and activation of certain promoters for amino acid biosynthesis and transport. The unusual nucleotide ppGpp plays an important role in both negative and positive regulation. Previously, we and ...
Chhun Tory - - 2005
Auxin influx carriers are involved in auxin transport and plant development. Here we show that the mutant of rice (Oryza sativa L. ssp. indica cv IR8) arm2 is defective in the uptake of the naturally occurring auxin indole-3-butyric acid (IBA). The acropetal and basipetal transport of IBA is reduced in ...
Whitley Alexander C - - 2005
Ellagic acid (EA), a polyphenol present in berries, has been demonstrated to be preventive of esophageal and colon cancer in animals. Here, we have studied the ability of organic anion transporters (OATs) and organic anion-transporting polypeptides (OATPs) to transport EA. The accumulation of radiolabeled (14)C]EA, [(3)H]p-aminohippuric acid (PAH), [(14)C]glutarate, [(3)H]estrone ...
Arias-Barrau Elsa - - 2005
The complete catabolic pathway involved in the assimilation of 3-hydroxyphenylacetic acid (3-OH-PhAc) in Pseudomonas putida U has been established. This pathway is integrated by the following: (i) a specific route (upper pathway), which catalyzes the conversion of 3-OH-PhAc into 2,5-dihydroxyphenylacetic acid (2,5-diOH-PhAc) (homogentisic acid, Hmg), and (ii) a central route ...
Wiwattanawongsa Kamonthip - - 2005
PURPOSE: A series of ester derivatives of mefenamic acid were synthesized with the aim of suppressing local gastrointestinal toxicity of mefenamic acid. A computational method was used to assist the design of the prodrug and to gain insights into the structure relationship of these compounds as P-glycoprotein (P-gp) substrates. The ...
Uchiyama Tomomi - - 2005
We describe the regulation mechanisms of the Na(+)-dependent neutral amino acid transporter ASCT2 via nitric oxide (NO) in the human intestinal cell line, Caco-2. Exposure of Caco-2 cells to S-nitrosothiol, such as S-nitroso-N-acetyl-DL-penicillamine (SNAP) and S-nitrosoglutathione, and the NO-donor, NOC12, concentration- and time-dependently increased Na(+)-dependent alanine uptake. Kinetic analyses indicated ...
Schwarz Jacob B - - 2005
As part of a program aimed at generating compounds with affinity for the alpha(2)-delta subunit of voltage-gated calcium channels, several novel beta-amino acids were prepared using an efficient nitroalkane-mediated cyclopropanation as a key step. Depending on the ester that was chosen, the target amino acids could be prepared in as ...
Goberdhan Deborah C I - - 2005
Growth in normal and tumour cells is regulated by evolutionarily conserved extracellular inputs from the endocrine insulin receptor (InR) signalling pathway and by local nutrients. Both signals modulate activity of the intracellular TOR kinase, with nutrients at least partly acting through changes in intracellular amino acid levels mediated by amino ...
Waterworth Wanda M - - 2005
Protein reserves in the cereal endosperm are sequentially degraded to small peptides and amino acids during germination and these are translocated across the scutellum to support growth of the embryo. Peptide transport in the germinating barley grain is mediated by specific carriers localized to the plasma membrane of the scutellar ...
Abuladze Natalia - - 2005
We have previously reported a topological model of the electrogenic Na(+)-HCO(3)(-) cotransporter (NBC1) in which the cotransporter spans the plasma membrane 10 times with N- and C-termini localized intracellularly. An analysis of conserved amino acid residues among members of the SLC4 superfamily in both the transmembrane segments (TMs) and intracellular/extracellular ...
Park Sun Young - - 2005
In order to understand the renal reabsorption mechanism of neutral amino acids via amino acid transporters, we have isolated human L-type amino acid transporter 2 (hLAT2) and human T-type amino acid transporter 1 (hTAT1) in human, then, we have examined and compared the gene structures, the functional characterizations and the ...
Regnault T R H - - 2005
Amino acids have multiple functions in fetoplacental development. The supply of amino acids to the fetus involves active transport across and metabolism within the trophoblast. Transport occurs through various amino acid transport systems located on both the maternal and fetal facing membranes, many of which have now been documented to ...
Zhou Shufeng - - 2005
5,6-Dimethylxanthenone-4-acetic acid (DMXAA), a potent cytokine inducer, exhibited marked antitumor activity when given as multiple oral doses in mice. The aim of this study was to examine the transport of DMXAA and its acyl glucuronide (DMXAA-G) using the human Caco-2 cells. DMXAA was minimally metabolized by Caco-2 cells and both ...
Neuhoff Sibylle - - 2005
The aim of this study was to investigate pH-dependent passive and active transport of acidic drugs across Caco-2 cells. Therefore, the bidirectional pH-dependent transport of two acidic drugs, indomethacin and salicylic acid, across Caco-2 cells was studied in the physiological pH range of the gastrointestinal tract. The transport of both ...
Habu Yasushi - - 2005
We previously reported that in hyperuricemic rats, renal impairment occurred and organic ion transport activity decreased, accompanied with a specific decrease in the expression of rat organic anion transporters, rOAT1 and rOAT3, and organic cation transporter, rOCT2. In the present study, we investigated the reversibility of the organic ion transport ...
Fernández Esperanza - - 2005
We have identified in silico arpAT, a gene encoding a new member of the LSHAT family, and cloned it from kidney. Co-expression of arpAT with the heavy subunits rBAT or 4F2hc elicited a sodium-independent alanine transport activity in HeLa cells. L-tyrosine, l-3,4-dihydroxyphenylalanine (L-DOPA), L-glutamine, L-serine, L-cystine, and L-arginine were also ...
Konishi Yutaka - - 2005
The absorption characteristics of rosmarinic acid (RA) were examined by measuring permeation across Caco-2 cell monolayers using an HPLC-electrochemical detector (ECD) fitted with a coulometric detection system. RA exhibited nonsaturable transport even at 30 mM, and the permeation at 5 mM in the apical-to-basolateral direction, J(ap-->bl), was 0.13 nmol/min/mg of ...
Javitt D C - - 2005
Clozapine is an atypical antipsychotic with particular efficacy in schizophrenia, possibly related to potentiation of brain N-methyl-D-aspartate receptor (NMDAR) -mediated neurotransmission. NMDARs are regulated in vivo by glycine, which is regulated in turn by glycine transporters. The present study investigates transport processes regulating glycine uptake into rat brain synaptosomes, along ...
Angelo S - - 2005
Experiments were carried out to test the hypothesis that system y(+)L accounts for the high (HT) and low (LT) amino-acid transport phenotypes in chicken erythrocytes and to explain the different effect of selective breeding on lysine and leucine fluxes. L: -Leucine transport was characterized in individuals which had been separated ...
Song Xueqin - - 2005
Gemcitabine, a clinically effective nucleoside anticancer agent, is a polar drug with low membrane permeability and is administered intravenously. Further, extensive degradation of gemcitabine by cytidine deaminase to an inactive metabolite in the liver affects its activity adversely. Thus, strategies that provide both enhanced transport and high metabolic bioevasion would ...
Song Xueqin - - 2005
Amino acid ester prodrugs of 2-bromo-5,6-dichloro-1-(beta-d-ribofuranosyl)benzimidazole (BDCRB) were synthesized and evaluated for their affinity for hPEPT1, an intestinal oligopeptide transporter. Assays of competitive inhibition of [(3)H]glycylsarcosine (Gly-Sar) uptake in HeLa/hPEPT1 cells by the amino acid ester prodrugs of BDCRB suggested their 2- to 4-fold higher affinity for hPEPT1 compared to ...
Konishi Yutaka - - 2005
m-Hydroxyphenylacetic acid (mHPA), 3,4-dihydroxyphenylacetic acid (DHPA), and 4-hydroxy-3-methoxyphenylacetic acid (HMPA) are major microbial metabolites of quercetin. After administration of quercetin to human subjects, these metabolites are readily detected in blood and urine. mHPA, DHPA, and HMPA are thought to exert protective biological activity within the body due to their antioxidant ...
Ganapathy V - - 2005
SLC5A8 is a candidate tumour suppressor gene that is silenced in colon cancer, gastric cancer and possibly other cancers in humans. This gene codes for a transporter belonging to the Na(+)/glucose co-transporter gene family (SLC5). The cancer-associated silencing of the gene involves hypermethylation of CpG islands present in exon 1 ...
Kraut Jeffrey A - - 2005
Hartnup disorder is an autosomal recessive disease that can be associated with neurological, psychiatric and dermatological abnormalities or be asymptomatic. Excessive intestinal and urinary loss of neutral amino acids is an essential feature of this disorder, which had been presumed to be due to hereditary abnormalities in an apical membrane-situated ...
Mitterhauser Markus - - 2005
In the last decade radiolabeled tropane analogs based on beta-CIT have proven indispensable for the imaging of the dopamine transporter. However, further improvements in their pharmacodynamic and pharmacokinetic features are desirable. An important improvement, yielding in higher affinity to the dopamine transporter (DAT) vs. serotonin transporter (SERT), can be achieved ...
Poulsen P - - 2005
Saccharomyces cerevisiae senses extracellular amino acids using two members of the family of amino acid transporters, Gap1 or Ssy1; aspects of the latter are reviewed here. Despite resemblance with bona fide transporters, Ssy1 appears unable to facilitate transport. Exposure of yeast to amino acids results in Ssy1-dependent transcriptional induction of ...
Gerk Phillip M - - 2005
Many drugs are removed from the body through a multistep process that includes covalent conjugation, transport into the bile, and excretion. Bile acids are transported across the ileocyte apical (brush border) membrane by the apical sodium-dependent bile-acid transporter (Asbt), but the identity of the primary transporter responsible for moving bile ...
Boudko Dmitri Y - - 2005
The biosynthesis of structural and signaling molecules depends on intracellular concentrations of essential amino acids, which are maintained by a specific system of plasma membrane transporters. We identify a unique population of nutrient amino acid transporters (NATs) within the sodium-neurotransmitter symporter family and have characterized a member of the NAT ...
Tanaka Kazunari - - 2005
We reported here the functional characteristics of Na+ -dependent neutral amino acid transport system A in normal human astrocytes and its adaptive regulation, a process in which amino acid starvation induces the transport activity. Reverse transcription-PCR revealed that the system A transporter subtype, SNAT2/ATA2, is only expressed in these cells. ...
Passeggio Jessica - - 2005
Niemann-Pick type C (NPC) is an autosomal recessive lipid storage disorder characterized by lysosomal accumulation of cholesterol and gangliosides resulting from a defect in intracellular lipid trafficking. The NPC1 gene encodes a 1278-amino acid integral membrane protein involved in the sub-cellular trafficking of lipids. The exact biological function of NPC1 ...
< 4 5 6 7 8 9 10 11 12 13 14 >