Search Results
Results 451 - 500 of 2421
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Takanaga Hitomi - - 2005
Amino acid homeostasis depends on specific amino acid transport systems, many of which have been characterized at the molecular level. However, the classical System IMINO, defined as the Na+-dependent proline transport activity that escapes inhibition by alanine, had not been identified at the molecular level. We report here the functional ...
Bhat Laxminarayan - - 2005
A series of novel steroidal pyrazoles was synthesized as substrates for bile acid transporters to explore their potential as drug carriers. The selected pyrazole fused bile acids were further conjugated with drugs and drug surrogates. Their in vitro transport activities were evaluated in human ileal bile acid transporter (hIBAT) and ...
Wasa Masafumi - - 2005
BACKGROUND: The potential mechanism of intestinal ischemia-reperfusion (I/R) injury includes oxygen-derived toxic free radicals. We tested the hypothesis that glutamine increases intracellular glutathione, a protective substrate against oxidative stress, by stimulating membrane amino acid transport during I/R using human intestinal epithelial cell line Caco-2. METHODS: Ischemic conditions were obtained by ...
Hössel D - - 2005
A study of transport and action of synthetic auxin analogues can help to identify transporters and receptors of this plant hormone. Both aspects--transportability and action on growth--were tested with 2-naphthoxyacetic acid (2-NOA) and compared across several plant species. 2-NOA stimulates elongation effectively at low concentrations in petioles of the gymnosperm ...
Friesema Edith C H - - 2005
Thyroid hormone is essential for the development of the brain and the nervous system. Cellular entry is required for conversion of thyroid hormones by the intracellular deiodinases and for binding of T(3) to its nuclear receptors. Several transporters capable of thyroid hormone transport have been identified. Functional expression studies using ...
Karim Zoubida - - 2005
To be appropriately excreted in urine, NH4+, the major component of urinary acid excretion, must be synthesized by proximal tubular cells, secreted into the proximal tubular fluid, reabsorbed by the medullary thick ascending limb (MTAL) to be accumulated in the medullary interstitium, and finally secreted in medullary collecting ducts. Several ...
Ho W S V - - 2005
Tissue concentrations of the endocannabinoids N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) are regulated by both synthesis and inactivation. The purpose of this review is to compile available data regarding three inactivation processes: fatty acid amide hydrolase, monoacylglycerol lipase, and cellular membrane transport. In particular, we have focused on mechanisms by which ...
Verrey François - - 2005
Reabsorption of amino acids, similar to that of glucose, is a major task of the proximal kidney tubule. Various amino acids are actively transported across the luminal brush border membrane into proximal tubule epithelial cells, most of which by cotransport. An important player is the newly identified cotransporter (symporter) B0AT1 ...
Taogoshi T - - 2005
The transport of prostaglandin E(1) (PGE(1)) across the blood-brain barrier (BBB) was characterized using an in-situ rat brain perfusion technique. The uptake of [(3)H]PGE(1) was not affected by shortchain monocarboxylic acids (butyric acid and valeric acid). On the other hand, uptake of [(3)H]PGE(1) was significantly inhibited by medium-chain monocarboxylic acids ...
Thamatrakoln Kimberlee - - 2005
A major component of the diatom cell wall is silica, derived from silicon taken up from the environment. Due to limiting environmental concentrations of silicon, and a substantial requirement during cell wall synthesis, diatoms must transport silicon into the cell against a steep concentration gradient. This is accomplished through the ...
Wilson John X - - 2005
Ascorbic acid and dehydroascorbic acid (DHAA, oxidized vitamin C) are dietary sources of vitamin C in humans. Both nutrients are absorbed from the lumen of the intestine and renal tubules by, respectively, enterocytes and renal epithelial cells. Subsequently vitamin C circulates in the blood and enters all of the other ...
Ring Troels - - 2005
The Canadian physiologist PA Stewart advanced the theory that the proton concentration, and hence pH, in any compartment is dependent on the charges of fully ionized and partly ionized species, and on the prevailing CO2 tension, all of which he dubbed independent variables. Because the kidneys regulate the concentrations of ...
Kennedy David J - - 2005
Functional characteristics and substrate specificity of the rat proton-coupled amino acid transporter 2 (rat PAT2 (rPAT2)) were determined following expression in Xenopus laevis oocytes using radiolabelled uptake measurements, competition experiments and measurements of substrate-evoked current using the two-electrode voltage-clamp technique. The aim of the investigation was to determine the structural ...
Dalpiaz A - - 2005
Diclofenac (Diclo), its ascorbic acid (AA) or 6-amino-AA (AA-NH2) pro-drugs (AA-Diclo or AA-NH-Diclo) were prepared and evaluated on human retinal pigment epithelium (HRPE) cells to investigate their ability to interact with the vitamin C transporter SVCT2 and their cellular uptake. Furthermore, stabilities in physiological fluids of these compounds were investigated. ...
Chen Cuiping - - 2005
The present study examined the interaction of four 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (atorvastatin, lovastatin, and simvastatin in acid and lactone forms, and pravastatin in acid form only) with multidrug resistance gene 1 (MDR1, ABCB1) P-glycoprotein, multidrug resistance-associated protein 2 (MRP2, ABCC2), and organic anion-transporting polypeptide 1B1 (OATP1B1, SLCO21A6). P-glycoprotein ...
Hyde Russell R Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dundee, - - 2005
Skeletal muscle is a major insulin target tissue and has a prominent role in the control of body amino acid economy, being the principal store of free and protein-bound amino acids and a dominant locus for amino acid metabolism. Interplay between diverse stimuli (e.g., hormonal/nutritional/mechanical) modulates muscle insulin action to ...
Besson Marie Thérèse - - 2005
Excitatory amino acid transporters (EAATs) are structurally related plasma membrane proteins known to mediate the Na(+)/K(+)-dependent uptake of the amino acids l-glutamate and dl-aspartate. In the nervous system, these proteins contribute to the clearance of glutamate from the synaptic cleft and maintain excitatory amino acid concentrations below excitotoxic levels. Two ...
Oppedisano Francesca - - 2004
The glutamine/amino acid transporter was solubilized from rat renal apical plasma membrane (brush-border membrane) with C12E8 and reconstituted into liposomes by removing the detergent from mixed micelles by hydrophobic chromatography on Amberlite XAD-4. The reconstitution was optimised with respect to the protein concentration, the detergent/phospholipid ratio and the number of ...
Franchi-Gazzola Renata - - 2004
In cultured human fibroblasts incubated under hypertonic conditions, the stimulation of system A for neutral amino acid transport, associated to the increased expression of the mRNA for SNAT2 transporter, leads to an expanded intracellular amino acid pool and to the recovery of cell volume. A protein of nearly 60 kDa, ...
Sato Hideyo - - 2004
Recent studies have demonstrated that depletion of amino acids results in the induction of several genes and that a genomic cis-element termed amino acid response element (AARE) is required for the induction. System x(c)(-) is an anionic amino acid transport system highly specific for cystine and glutamate, and its activity ...
Boado Ruben J - - 2004
The deleterious effects on the brain of phenylketonuria are caused by the saturation of the blood-brain barrier large neutral amino acid transporter type 1 (LAT1) by high plasma phenylalanine concentrations. There is only one known single nucleotide polymorphism (SNP) of the open reading frame of human LAT1, N230K. Site-directed mutagenesis ...
Sahmoune Amar - - 2004
The solvent extraction of chromium(VI) in chloroform, dichloromethane, dichloroethane and its transport through a chloroformic bulk liquid membrane from sulphuric acid solutions with the neutral extractant triphenylphosphine (TPP) were studied. It was highlighted that the TPP extractant is an interesting complexing and efficient carrier for transport of chromium(VI) as [(HTPP)HCr2O7] ...
Kim Do Kyung - - 2004
The system L-amino acid transporter is a major nutrient transport system that is responsible for Na+-independent transport of neutral amino acids including several essential amino acids. We have compared and examined the expressions and functions of the system L-amino acid transporters in both rat astrocyte cultures and C6 glioma cells. ...
Bergmann Ralf - - 2004
(18)F-Labeled amino acids represent a promising class of imaging agents in tumors, particularly brain tumors. However, the determination of their potential to image peripheral tumors, possibly depending on individual transport characteristics, still remains an area of investigation. The present study investigated the transport mechanism for 3-O-methyl-6-(18)F-fluoro-L-dopa (OMFD), a novel (18)F-labeled ...
Velasco Isabel - - 2004
Excretion of amino acids by yeast cells was reported long ago but has not been characterized in molecular terms. It is typically favored by overproduction of the amino acid and/or impairment of its uptake. Here we describe the construction of a yeast strain excreting threonine and homoserine. Using this excretor ...
Dawson Paul A PA Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA. - - 2005
Bile acids are transported across the ileal enterocyte brush border membrane by the well characterized apical sodium-dependent bile acid transporter (Asbt) Slc10a2; however, the carrier(s) responsible for transporting bile acids across the ileocyte basolateral membrane into the portal circulation have not been fully identified. Transcriptional profiling of wild type and ...
Pohl Jürgen - - 2004
Long-chain fatty acids (LCFAs) represent key metabolites for energy generation and storage. Transport and metabolism of LCFA are believed to be regulated by membrane-associated proteins that bind and transport LCFA. Identifying the postulated fatty acid transporters is of considerable interest since altered fatty acid uptake has been implicated in disease ...
Yoon Jung Hoon - - 2005
Previously, we reported the expression and function of system L amino acid transporter in KB human oral epidermoid carcinoma cells. In the present study, therefore, we investigated the expression and function of system L amino acid transporter in human normal oral keratinocytes (HNOK) and compared the expressions and functions of ...
Howard Alison - - 2004
Intestinal function depends on the presence of luminal nutrients and is altered during starvation and refeeding. Amino acids are essential for enterocytes, but the luminal supply is compromised with changes in dietary intake. To test the hypothesis that during periods of restricted luminal nutrient availability mucosal cells undergo adaptations aimed ...
Anderson Catriona M H - - 2004
BACKGROUND AND AIMS: Amino acid (and related drug) absorption across the human small intestinal wall is an essential intestinal function. Despite the revelation of a number of mammalian genomes, the molecular identity of the classic Na(+)-dependent imino acid transporter (identified functionally in the 1960s) remains elusive. The aims of this ...
Wang Szu-Wen - - 2004
Excipients often used in pharmaceutical formulations have been reported to have inhibitory effects on P-glycoprotein, an important membrane-associated transport protein. Because inhibition of efflux transporters can have an effect on drug bioavailability, identification of these excipients and their extent of inhibition are therefore important for pharmaceutical development. We have developed ...
Liu Ming - - 2004
4-Phenylbutyrate (PB) induces differentiation and is being intensively studied as a treatment for brain, prostate, breast, and hematopoietic cancer. While many different primary targets for PB have been proposed, the mechanism by which it causes cellular differentiation remains unknown. To identify the primary cellular target, we investigated its effects on ...
Dietrich Daniela - - 2004
For the efficient translocation of organic nitrogen, small peptides of two to three amino acids are posited as an important alternative to amino acids. A new transporter mediating the uptake of di- and tripeptides was isolated from Arabidopsis thaliana by heterologous complementation of a peptide transport-deficient Saccharomyces cerevisiae mutant. AtPTR1 ...
Konishi Yutaka - - 2004
It was previously reported that m-coumaric acid, m-hydroxyphenylpropionic acid (mHPP), and 3,4-dihydroxyphenylpropionic acid (DHPP) are major metabolites of ingested caffeic acid formed by gut microflora and would be transported by the monocarboxylic acid transporter (MCT). We have directly measured their absorption characteristics in Caco-2 cells using a coulometric detection method ...
Verri Tiziano - - 2005
Information regarding cationic amino acid transport systems in thyroid is limited to Northern blot detection of y(+)LAT1 mRNA in the mouse. This study investigated cationic amino acid transport in PC cell line clone 3 (PC Cl3 cells), a thyroid follicular cell line derived from a normal Fisher rat retaining many ...
Rohloff Peter - - 2004
Trypanosoma cruzi, the etiologic agent of Chagas disease, resists extreme fluctuations in osmolarity during its life cycle. T. cruzi possesses a robust regulatory volume decrease mechanism that completely reverses cell swelling when submitted to hypo-osmotic stress. The efflux of amino acids and K+ release could account for only part for ...
Closs Ellen I - - 2004
The supply of arginine may become rate limiting for enzymatic reactions that use this semiessential amino acid as a substrate (e.g., nitric oxide, agmatine, creatine, and urea synthesis), particularly under conditions of high demand such as growth, sepsis, or wound healing. In addition, arginine acts as a signaling molecule that ...
Artusi Mariella - - 2004
The aim of this work was to study the permeation of thiocolchicoside across the skin in vitro. The effect of the chemical enhancer lauric acid and the physical technique of iontophoresis was investigated. Permeation experiments were performed in vitro using rabbit ear skin as barrier. The effect of lauric acid ...
Schousboe Arne - - 2004
Inactivation of gamma-aminobutric acid (GABA) as a neurotransmitter is mediated by diffusion in the synaptic cleft followed by binding to transporter sites and translocation into the intracellular compartment. The GABA transporters of which four subtypes have been cloned (GAT1-4) are distributed at presynaptic nerve endings as well as extrasynaptically on ...
Speake Paul F - - 2004
OBJECTIVES: Pregnant women undergoing long-term organ transplant treatment have an increased incidence of delivering infants with intrauterine growth restriction (IUGR). Cyclosporine A is used as an immunosuppressant in such women and indirect evidence suggests that IUGR might result from an effect of cyclosporine A on amino acid transport by the ...
Lee Yong-Hwa - - 2004
Within the flower, microsporogenesis represents a major sink for nitrogen, but knowledge on how the imported nitrogen is transferred from the anther cell layers to developing pollen is lacking. Here, we provide information on characterization of a transporter (AtLHT2) that might play an important role in partitioning of amino acids ...
Ohtsuki Sumio - - 2004
The blood-brain barrier (BBB) segregates the circulating blood from interstitial fluid in the brain, and restricts drug permeability into the brain. Our latest studies have revealed that the BBB transporters play important physiological roles in maintaining the brain milieu. The BBB supplies creatine to the brain for an energy-storing system, ...
Bridges Christy C - - 2004
Proximal tubular epithelial cells are major sites of homocysteine (Hcy) metabolism and are the primary sites for the accumulation and intoxication of inorganic mercury (Hg(2+)). Previous in vivo data from our laboratory have demonstrated that mercuric conjugates of Hcy are transported into these cells by unknown mechanisms. Recently, we established ...
Su Yan-Hua - - 2004
More than 50 distinct amino acid transporter genes have been identified in the genome of Arabidopsis, indicating that transport of amino acids across membranes is a highly complex feature in plants. Based on sequence similarity, these transporters can be divided into two major superfamilies: the amino acid transporter family and ...
Okumoto Sakiko - - 2004
Amino acids are regarded as the nitrogen 'currency' of plants. Amino acids can be taken up from the soil directly or synthesized from inorganic nitrogen, and then circulated in the plant via phloem and xylem. AtAAP3, a member of the Amino Acid Permease (AAP) family, is mainly expressed in root ...
Foltz Martin - - 2004
Recently, the PAT family of proton-dependent amino acid transporters has been identified as a novel class of mammalian amino acid symporters. PAT1 and PAT2 members mediate electrogenic uptake of small, neutral amino acids and derivatives by cotransport of protons. Analysis of the structural requirements for substrate recognition by PAT1 identified ...
Jain-Vakkalagadda Blisse - - 2004
The purpose of this study was to identify and functionally characterize an active transport system for L-arginine on rabbit corneal epithelium and human cornea and study its interaction with the amino acid ester prodrugs of acyclovir (Anand, B. S.; Mitra, A. K. Pharm. Res. 2002, 19, 1194-1202). Transport characteristics of ...
Aydin Atakan - - 2004
Medicinal leech, Hirudo medicinalis, has been used in plastic and reconstructive surgery, to relieve venous congestion and to improve the microrevascularization of flaps. In many countries, wild leeches are still provided from local markets and utilised with antibiotic prophylaxies. In this research, results of identification of bacteria in the transport ...
de Vrijer Barbra - - 2004
Reductions in fetal plasma concentrations of certain amino acids and reduced amino acid transport in vesicle studies suggest impaired placental amino acid transport in human fetal growth restriction (FGR). In the present study, we tested the hypothesis of an impairment in amino acid transport in the ovine model of hyperthermia-induced ...
Gopal Elangovan - - 2004
We report here on the expression of slc5a8 in kidney and its relevance to Na(+)-coupled reabsorption of lactate. slc5a8 is the murine ortholog of SLC5A8, a candidate tumor suppressor gene, which we recently cloned from human intestine and demonstrated its functional identity as a Na(+)-coupled transporter for short-chain fatty acids ...
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