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241.
Preferential vulnerability of mesencephalic dopamine neurons to glutamate transporter dysfunction 总被引:2,自引:0,他引:2
Nafia I Re DB Masmejean F Melon C Kachidian P Kerkerian-Le Goff L Nieoullon A Had-Aissouni L 《Journal of neurochemistry》2008,105(2):484-496
Nigral depletion of the main brain antioxidant GSH is the earliest biochemical event involved in Parkinson's disease pathogenesis. Its causes are completely unknown but increasing number of evidence suggests that glutamate transporters [excitatory amino acid transporters (EAATs)] are the main route by which GSH precursors may enter the cell. In this study, we report that dopamine (DA) neurons, which express the excitatory amino acid carrier 1, are preferentially affected by EAAT dysfunction when compared with non-DA neurons. In rat embryonic mesencephalic cultures, l -trans-pyrrolidine-2,4-dicarboxylate, a substrate inhibitor of EAATs, is directly and preferentially toxic for DA neurons by decreasing the availability of GSH precursors and lowering their resistance threshold to glutamate excitotoxicity through NMDA-receptors. In adult rat, acute intranigral injection of l -trans-pyrrolidine-2,4-dicarboxylate induces a large regionally selective and dose-dependent loss of DA neurons and α-synuclein aggregate formation. These data highlight for the first time the importance of excitatory amino acid carrier 1 function for the maintenance of antioxidant defense in DA neurons and suggest its dysfunction as a candidate mechanism for the selective death of DA neurons such as occurring in Parkinson's disease. 相似文献
242.
价格随供求变化的捕获问题 总被引:10,自引:0,他引:10
本文对开放式渔场建立了价格随供求而变化的捕获模型,对模型进行了详细的分析,并从生态学和经济学的角度对结果作了解释。为生物资源的实际管理提供了理论依据。 相似文献
243.
Mourey L Da Re S Pédelacq JD Tolstykh T Faurie C Guillet V Stock JB Samama JP 《The Journal of biological chemistry》2001,276(33):31074-31082
The x-ray crystal structure of the P1 or H domain of the Salmonella CheA protein has been solved at 2.1-A resolution. The structure is composed of an up-down up-down four-helix bundle that is typical of histidine phosphotransfer or HPt domains such as Escherichia coli ArcB(C) and Saccharomyces cerevisiae Ypd1. Loop regions and additional structural features distinguish all three proteins. The CheA domain has an additional C-terminal helix that lies over the surface formed by the C and D helices. The phosphoaccepting His-48 is located at a solvent-exposed position in the middle of the B helix where it is surrounded by several residues that are characteristic of other HPt domains. Mutagenesis studies indicate that conserved glutamate and lysine residues that are part of a hydrogen-bond network with His-48 are essential for the ATP-dependent phosphorylation reaction but not for the phosphotransfer reaction with CheY. These results suggest that the CheA-P1 domain may serve as a good model for understanding the general function of HPt domains in complex two-component phosphorelay systems. 相似文献
244.
Adhesion, autoaggregation and hydrophobicity of 13 strains of Bifidobacterium longum 总被引:1,自引:0,他引:1
To identify bacterial traits related to adhesion ability in human bifidobacteria, 13 strains of Bifidobacterium longum isolated from human gastric juice and intestine were studied. Strains were tested for their capability to adhere to Caco-2 cells and classified as adhesive (Adh+) or non-adhesive (Adh-). Adh+ and Adh- strains were then investigated for their autoaggregation ability and surface hydrophobicity. Comparing the properties of Adh+ and Adh-, we observed that strains were able to adhere to cell monolayers if they autoaggregate and manifest a good degree of hydrophobicity as determined by microbial adhesion to hydrocarbons. These two traits could be used for preliminary screening to identify potentially adherent isolates. 相似文献
245.
Bourbon HM Aguilera A Ansari AZ Asturias FJ Berk AJ Bjorklund S Blackwell TK Borggrefe T Carey M Carlson M Conaway JW Conaway RC Emmons SW Fondell JD Freedman LP Fukasawa T Gustafsson CM Han M He X Herman PK Hinnebusch AG Holmberg S Holstege FC Jaehning JA Kim YJ Kuras L Leutz A Lis JT Meisterernest M Naar AM Nasmyth K Parvin JD Ptashne M Reinberg D Ronne H Sadowski I Sakurai H Sipiczki M Sternberg PW Stillman DJ Strich R Struhl K Svejstrup JQ Tuck S Winston F Roeder RG Kornberg RD 《Molecular cell》2004,14(5):553-557
246.
HIV-1 Vpr induces defects in mitosis, cytokinesis, nuclear structure, and centrosomes 总被引:3,自引:0,他引:3
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Human immunodeficiency virus type 1 (HIV-1) Vpr is a 15-kDa accessory protein that contributes to several steps in the viral replication cycle and promotes virus-associated pathology. Previous studies demonstrated that Vpr inhibits G2/M cell cycle progression in both human cells and in the fission yeast Schizosaccharomyces pombe. Here, we report that, upon induction of vpr expression, fission yeast exhibited numerous defects in the assembly and function of the mitotic spindle. In particular, two spindle pole body proteins, sad1p and the polo kinase plo1p, were delocalized in vpr-expressing yeast cells, suggesting that spindle pole body integrity was perturbed. In addition, nuclear envelope structure, contractile actin ring formation, and cytokinesis were also disrupted. Similar Vpr-induced defects in mitosis and cytokinesis were observed in human cells, including aberrant mitotic spindles, multiple centrosomes, and multinucleate cells. These defects in cell division and centrosomes might account for some of the pathological effects associated with HIV-1 infection. 相似文献
247.
Hoellinger H Re M Deroussent A Singh RP Cresteil T 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2004,799(2):195-200
Sanguinarine is a quaternary benzo[c]phenanthridine alkaloid, extracted from the argemone oil, which produced severe human intoxications. To investigate the sanguinarine biotransformation, we develop a simple extraction process and a high performance liquid chromatographic separation coupled to a sensitive fluorometric detection of sanguinarine in cell culture medium, as well as in rat urine and plasma. After extraction with an acidified organic solvent, sanguinarine elution is performed within 15 min on a Nucleosil C18 column with a gradient using 0.2% formic acid/water/acetonitrile as mobile phase. Extracted and standard sanguinarine are characterized by mass spectrometry. The extraction recovery of sanguinarine is about 80% in cell culture medium and in rat urine, but lower in plasma. This convenient high performance liquid chromatography (HPLC) method allows to quantify sanguinarine over concentrations ranged 10-2000 ng ml(-1). The limit of fluorometric detection is 0.5 ng. Under these conditions, the lower limit of quantification of sanguinarine is 50 ng ml(-1) in cell culture medium and in rat urine and 100 ng ml(-1) in rat plasma. This analytical HPLC method is specific, linear and reproducible in all media and is suitable for quantitative determination of sanguinarine in biological fluids. 相似文献
248.
Editorial
Editorial 相似文献249.