457 resultados para NAD
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La voie de signalisation des phosphoinositides joue un rle cl dans la rgulation du tonus vasculaire. Plusieurs tudes rapportent une production endogne de langiotensin II (Ang II) et de lendothline-1 (ET-1) par les cellules musculaires lisses vasculaires (CMLVs) de rats spontanment hypertendus (spontaneously hypertensive rats : SHR). De plus, lAng II exogne induit son effet prohypertrophique sur les CMLVs selon un mcanisme dpendant de la protine Gq et de la PKC. Cependant, le rle de laxe Gq/PLC/PKC dans lhypertrophie des CMLVs provenant dun modle animal de lhypertension artrielle nest pas encore tudi. Lobjectif principal de cette thse est dexaminer le rle de laxe Gq/PLC1 dans les mcanismes molculaires de lhypertrophie des CMLVs provenant dun modle animal dhypertension artrielle essentielle (spontaneously hypertensive rats : SHR). Nos premiers rsultats indiquent que contrairement aux CMLVs de SHR gs de 12 semaines (absence dhypertrophie cardiaque), les CMLVs de SHR gs de 16 semaines (prsence dhypertrophie cardiaque) prsentent une surexpression protique endogne de Gq et de PLC1 par rapport aux CMLVs de rats WKY apparis pour lge. Linhibition du taux dexpression protique de Gq et de PLC1 par des siRNAs spcifiques diminue significativement le taux de synthse protique lev dans les CMLVs de SHR. De plus, la surexpression endogne des Gq et PLC1, lhyperphosphorylation de la molcule ERK1/2 et le taux de synthse protique lev dans les CMLVs de SHR de 16 semaines ont t attnus significativement par des antagonistes des rcepteurs AT1 (losartan) et ETA (BQ123), mais pas par lantagoniste du rcepteur ETB (BQ788). Linhibition pharmacologique des MAPKs par PD98059 diminue significativement la surexpression endogne de Gq/PLC1 et le taux de synthse protique lev dans les CMLVs de SHR. Dun ct, linhibition du stress oxydatif (par DPI, inhibiteur de la NAD(P)H oxidase, et NAC , molcule anti-oxydante), de la molcule c-Src (PP2) et des rcepteurs de facteurs de croissance (AG1024 (inhibiteur de lIGF1-R), AG1478 (inhibiteur de lEGFR) et AG1295 (inhibiteur du PDGFR)) a permis dattnuer significativement la surexpression endogne leve de Gq/PLC1 et lhypertrophie des CMLVs de SHR. Dun autre ct, DPI, NAC et PP2 attnuent significativement lhyperphosphorylation de la molcule c-Src, des RTKs (rcepteurs activit tyrosine kinase) et de la molcule ERK1/2. Dans une autre tude, nous avons aussi dmontr que la PKC montre une hyperphosphorylation en Tyr311 dans les CMLVs de SHR compares aux CMLVs de WKY. La rottlerin, utilise comme inhibiteur spcifique de la PKC, inhibe significativement cette hyperphosphorylation en Tyr311 dpendamment de la concentration. Linhibition de lactivit de la PKC par la rottlerin a t aussi associe une attnuation significative de la surexpression protique endogne de Gq/PLC1 et lhypertrophie des CMLVs de SHR. De plus, linhibition pharmacologique de lactivit de la PKC, en amont du stress oxydatif, a permis dinhiber significativement lactivit de la NADPH, le taux de production leve de lion superoxyde ainsi que lhyperphosphorylation de la molcule ERK1/2, de la molcule c-Src et des RTKs. notre surprise, nous avons aussi remarqu une surexpression protique de lEGFR et de lIGF-1R dans les CMLVs de SHR lge de 16 semaines. Linhibition pharmacologique de lactivit de la PKC, de la molcule c-Src et du stress oxydatif a permis dinhiber significativement la surexpression protique endogne de ces RTKs. De plus, linhibition de lexpression protique de lEGFR et de la molcule c-Src par des siRNA spcifiques attnue significativement le taux dexpression protique lev de Gq et de PLC1 ainsi que le taux de synthse protique lev dans les CMLVs de SHR. Des siRNAs spcifiques la PKC ont permis dattnuer significativement le taux de synthse protique lev dans les CMLVs de SHR et confirment le rle important de la PKC dans les mcanismes molculaires de lhypertrophie des CMLVs selon une voie dpendante du stress oxydatif. En conclusion, ces rsultats suggrent un rle important de lactivation endogne de laxe Gq-PLC-PKC dans le processus dhypertrophie vasculaire selon un mcanisme impliquant une activation endogne des rcepteurs AT1/ETa, de la molcule c-Src, du stress oxidatif, des RTKs et des MAPKs.
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Translation of Wieczory nad Lemanem.
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Each volume has also special title page.
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At head of title: Vseobshch evresk raboch soiuz v Litvie, Polshie i Rossi. Histoire sanglante Yakoutsk.
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Mode of access: Internet.
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t.3. Pamiatki i wypadki historyczne od wieku szstego po wiek trzynasty, tudziez rzeczy odnoszace sie do Prussyi, otwy, zakonw rycerskich.--t.4 [Dzieje odnoszace sie do Xieztwa Litewsko-zawilejskiego].--t.5. Od mierci Gedymina do bitwy nad Worska.--t.6. Panowanie Witolda w wieku pietnastym.--t.7. Panowanie Swidrygey i Zygmunta.--t.8. Panowania Kazimierza i Alexandra.--t.9. Panowania Zygmuntw.
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1. Teorya smaku w dzieach sztuk piknych. Uwagi powszechne nad jzykami, sztuk pisania i postaciami mowy.--2. Teorya wymowy. Teorya poezyi. Rosprawa o sztuce dobrego pisania w izyku polskim. Przestrogi wzgldem wprawiania uczniw do dobrego w izyku polskim pisania.--3. Rozbiory pisarzw. Przykady stylu w prozie.--4.Poezye wasne i przekady.
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Structure from Motion (SfM) is a new form of photogrammetry that automates the rendering of georeferenced 3D models of objects using digital photographs and independently surveyed Ground Control Points (GCPs). This project seeks to quantify the error found in Digital Elevation Models (DEMs) produced using SfM. I modeled a rockslide found at the Cadman Quarry (Monroe, Washington) because the surface is vegetation-free, which is ideal for SfM and Terrestrial LiDAR Scanner (TLS) surveys. By using SfM, TLS, and GPS positioning at the same time, I attempted to find the deviation in the SfM model from the TLS model and GPS points. Using the deviation, I found the Root-Mean-Square Error (RMSE) between the SfM DEM and GPS positions. The RMSE of the SfM model when compared to surveyed GPS points is 17cm. I propagated the uncertainty of the GPS points with the RMSE of the SfM model to find the uncertainty of the SfM model compared to the NAD 1984 datum. The uncertainty of the SfM model compared to the NAD 1984 is 27cm. This study did not produce a model from the TLS that had sufficient resolution on horizontal surfaces to compare to surveyed GPS points.
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Aim To evaluate whether the T1D susceptibility locus on chromosome 16q contributes to the genetic susceptibility to T1D in Russian patients. Method Thirteen microsatellite markers, spanning a 47-centimorgan genomic region on 16q22-q24 were evaluated for linkage to T1D in 98 Russian multiplex families. Multipoint logarithm of odds (LOD) ratio (MLS) and nonparametric LOD (NPL) values were computed for each marker, using GENEHUNTER 2.1 software. Four microsatellites (D16S422, D16S504, D16S3037, and D16S3098) and 6 biallelic markers in 2 positional candidate genes, ICSBP1 and NQO1, were additionally tested for association with T1D in 114 simplex families, using transmission disequilibrium test (TDT). Results A peak of linkage (MLS = 1.35, NPL = 0.91) was shown for marker D16S750, but this was not significant (P = 0.18). The subsequent linkage analysis in the subset of 46 multiplex families carrying a common risk HLA-DR4 haplotype increased peak MLS and NPL values to 1.77 and 1.22, respectively, but showed no significant linkage (P = 0.11) to T1D in the 16q22-q24 genomic region. TDT analysis failed to find significant association between these markers and disease, even after the conditioning for the predisposing HLA-DR4 haplotype. Conclusion Our results did not support the evidence for the susceptibility locus to T1D on chromosome 16q22-24 in the Russian family data set. The lack of association could reflect genetic heterogeneity of type 1 diabetes in diverse ethnic groups.
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Oxidoreductase enzymes catalyze single- or multi-electron reduction/oxidation reactions of small molecule inorganic or organic substrates, and they are integral to a wide variety of biological processes including respiration, energy production, biosynthesis, metabolism, and detoxification. All redox enzymes require a natural redox partner such as an electron-transfer protein ( e. g. cytochrome, ferredoxin, flavoprotein) or a small molecule cosubstrate ( e. g. NAD(P)H, dioxygen) to sustain catalysis, in effect to balance the substrate/product redox half-reaction. In principle, the natural electron-transfer partner may be replaced by an electrochemical working electrode. One of the great strengths of this approach is that the rate of catalysis ( equivalent to the observed electrochemical current) may be probed as a function of applied potential through linear sweep and cyclic voltammetry, and insight to the overall catalytic mechanism may be gained by a systematic electrochemical study coupled with theoretical analysis. In this review, the various approaches to enzyme electrochemistry will be discussed, including direct and indirect ( mediated) experiments, and a brief coverage of the theory relevant to these techniques will be presented. The importance of immobilizing enzymes on the electrode surface will be presented and the variety of ways that this may be done will be reviewed. The importance of chemical modification of the electrode surface in ensuring an environment conducive to a stable and active enzyme capable of functioning natively will be illustrated. Fundamental research into electrochemically driven enzyme catalysis has led to some remarkable practical applications. The glucose oxidase enzyme electrode is a spectacularly successful application of enzyme electrochemistry. Biosensors based on this technology are used worldwide by sufferers of diabetes to provide rapid and accurate analysis of blood glucose concentrations. Other applications of enzyme electrochemistry are in the sensing of macromolecular complexation events such as antigen - antibody binding and DNA hybridization. The review will include a selection of enzymes that have been successfully investigated by electrochemistry and, where appropriate, discuss their development towards practical biotechnological applications.
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The complex molybdoenzyme xanthine oxidase (XO) catalyses the oxidation of xanthine to uric acid. Here we report the first direct (unmediated) catalytic electrochemistry of the enzyme in the presence of xanthine. The only non-turnover response (without substrate present) is a sharp two-electron wave from the FAD cofactor at -242 mV vs. NHE (pH 8.0). Upon addition of xanthine to the electrochemical cell a pronounced electrocatalytic anodic current appears at ca. +300 mV vs. NHE, but the FAD peak remains. This is unusual as the onset of catalysis should occur at the potential of the FAD cofactor (the site at which oxygen or NAD+ binds to the enzyme in solution). The observed electrochemical catalysis is prevented by the addition of known XO inhibitors allopurinol or cyanide. (c) 2005 Elsevier B.V. All rights reserved.
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Proton pumping nicotinamide nucleotide transhydrogenase from Escherichia coli contains an subunit with the NAD(H)-binding domain I and a subunit with the NADP(H)-binding domain III. The membrane domain (domain II) harbors the proton channel and is made up of the hydrophobic parts of the and subunits. The interface in domain II between the and the subunits has previously been investigated by cross-linking loops connecting the four transmembrane helices in the subunit and loops connecting the nine transmembrane helices in the subunit. However, to investigate the organization of the nine transmembrane helices in the subunit, a split was introduced by creating a stop codon in the loop connecting transmembrane helices 9 and 10 by a single mutagenesis step, utilizing an existing downstream start codon. The resulting enzyme was composed of the wild-type subunit and the two new peptides 1 and 2. As compared to other split membrane proteins, the new transhydrogenase was remarkably active and catalyzed activities for the reduction of 3-acetylpyridine-NAD + by NADPH, the cyclic reduction of 3-acetylpyridine-NAD + by NADH (mediated by bound NADP(H)), and proton pumping, amounting to about 50-107% of the corresponding wild-type activities. These high activities suggest that the subunit was normally folded, followed by a concerted folding of 1 + 2. Cross-linking of a S105C-S237C double cysteine mutant in the functional split cysteine-free background, followed by SDS-PAGE analysis, showed that helices 9, 13, and 14 were in close proximity. This is the first time that cross-linking between helices in the same subunit has been demonstrated.
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The imidazotetrazinones are clinically active antitumour agents, temozolomide currently proving successful in the treatment of melanomas and gliomas. The exact nature of the biological processes underlying response are as yet unclear.This thesis attempts to identify the cellular targets important to the cytotoxicity of imidazotetrazinones, to elucidate the pathways by which this damage leads to cell death, and to identify mechanisms by which tumour cells may circumvent this action. The levels of the DNA repair enzymes O6-alkylguanine-DNA-alkyltransferase (O6-AGAT) and 3-methyladenine-DNA-glycosylase (3MAG) have been examined in a range of murine and human cell lines with differential sensitivity to temozolomide. All the cell lines were proficient in 3MAG despite there being 40-fold difference in sensitivity to temozolomide. This suggests that while 3-methyladenine is a major product of temozolomide alkylation of DNA it is unlikely to be a cytotoxic lesion. In contrast, there was a 20-fold variation in O6-AGAT levels and the concentration of this repair enzyme correlated with variations in cytotoxicity. Furthermore, depletion of this enzyme in a resistant, O6-AGAT proficient cell line (Raji), by pre-treatment with the free base O6-methylguanine resulted in 54% sensitisation to the effects of temozolomide. These observations have been extended to 3 glioma cell lines; results that support the view that the cytotoxicity of temozolomide is related to alkylation at the O6-position of guanine and that resistance to this drug is determined by efficient repair of this lesion. It is clear, however, the other factors may influence tumour response since temozolomide showed little differential activity towards 3 established solid murine tumours in vivo, despite different tumour O6-AGAT levels. Unlike mitozolomide, temozolomide is incapable of cross-linking DNA and a mechanism by which O6-methylguanine may exert lethality is unclear. The cytotoxicity of the methyl group may be due to its disruption of DNA-protein interactions, or alternatively cell death may not be a direct result of the alkyl group itself, but manifested by DNA single-strand breaks. Enhanced alkaline elution rates were found for the DNA of Raji cells treated with temozolomide following alkyltransferase depletion, suggesting a relationship between O6-methylguanine and the induction single-strand breaks. Such breaks can activate poly(ADP-ribose) synthetase (ADPRT) an enzyme capable of rapid and lethal depletion of cellular NAD levels. However, at concentrations of temozolomlde relevant in vivo little change in adenine nucleotides was detected in cell lines, although this enzyme would appear important in modulating DNA repair since inhibition of ADPRT potentiated temozolomide cytotoxicity in Raji cells but not O6-AGAT deficient GM892A cells. Cell lines have been reported that are O6-AGAT deficient yet resistant to methylating agents. Thus, resistance to temozolomide may arise not only by removal of the methyl group from the O6-position of guanine, but also from another mechanism involving caffeine-sensitive post-replication repair or mismatch repair activity. A modification of the standard Maxam Gilbert sequencing technique was used to determine the sequence specificity of guanine-N7 alkylation. Temozolomide preferentially alkylated runs of guanines with the intensity of reaction increasing with the number of adjacent guanines in the DNA sequence. Comparable results were obtained with a polymerase-stop assay, although neither technique elucidates the sequence specificity of O6-guanine alkylation. The importance of such specificity to cytotoxicity is uncertain, although guanine-rich sequences are common to the promoter regions of oncogenes. Expression of a plasmid reporter gene under the control of the Ha-ras proto~oncogene promoter was inhibited by alkylation with temozolomide when transfected into cancer cell lines, However, this inhibition did not appear to be related to O6~guanine alkylation and therefore would seem unimportant to the chemotherapeutic activity of temozolomide.
