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排序方式: 共有428条查询结果,搜索用时 15 毫秒
1.
Se-Chan Kim Alexander Ghanem Heidi Stapel Klaus Tiemann Pascal Knuefermann Andreas Hoeft Rainer Meyer Christian Grohé Anne A Knowlton Georg Baumgarten 《BMC physiology》2007,7(1):5
Backgound
It has been reported that Toll-like receptor 4 (TLR4) deficiency reduces infarct size after myocardial ischemia/reperfusion (MI/R). However, measurement of MI/R injury was limited and did not include cardiac function. In a chronic closed-chest model we assessed whether cardiac function is preserved in TLR4-deficient mice (C3H/HeJ) following MI/R, and whether myocardial and systemic cytokine expression differed compared to wild type (WT). 相似文献2.
N. Ghanem J. M. Lobaccaro C. Buresi M. Abbal G. Halaby C. Sultan G. Lefranc 《Human genetics》1990,86(2):117-125
Summary Defects in the enzyme, steroid 21-hydroxylase, result in congenital adrenal hyperplasia (CAH), a common autosomal recessive disorder of cortisol biosynthesis. The gene encoding this protein (CYP21B) and a closely linked pseudogene (CYP21A) have been mapped in the HLA complex on chromosome 6p, adjacent to the complement genes C4B and C4A, about 80 kb from the factor B gene. Molecular analyses of patients with CAH have shown that the cause of the defect may be either a deletion, a point mutation or a conversion of the active gene. Linkage of the disease to HLA has previously been studied by several groups. We have analyzed DNAs from patients with classical and non-classical CAH and from their family members, by probing with CYP21, C4 and BF cDNAs. In 70% of the CAH haplotypes studied, the defective CYP21B gene was indistinguishable from its structurally intact corresponding gene in Southern blot analysis, and presumably bore point mutations. In the remaining chromosomes, evidence for gene conversions, deletions and various deleterious mutations of the CYP21B gene is given. Moreover, our linkage studies show that a polymorphic TaqI cleavage site in the factor B gene, recently described by us, may be a new and useful genetic marker, because we found this TaqI restriction site only in unaffected haplotypes carrying functional CYP21B genes and, therefore, in negative association with the defective CYP21B gene. 相似文献
3.
G Ghanem J Verstegen A Libert R Arnould F Lejeune 《Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society》1989,2(6):519-523
Seven human melanoma metastases were extracted in order to check the possible presence of any alpha-melanocyte stimulating hormone (MSH) immunoreactivity. The aim of that study was to provide some explanation for, mainly, two observations that we have already made and reported: 1) increased plasma alpha-MSH levels in melanoma of tumour-bearing patients as compared with tumour-free patients; 2) the presence of specific alpha-MSH receptors on human melanoma cells in culture. We could measure large amounts of immunoreactive alpha-MSH in all tumours ranging from 0.31 to 4.27 pmoles per g of wet tissue. Further identification of the extracted material by high-performance liquid chromatography revealed compounds of higher molecular weight and more hydrophobic than synthetic alpha-MSH. In addition, purified extracts could also displace 125I-labelled alpha-MSH from its cellular binding sites in an alpha-MSH specific radio-receptor binding assay. Our findings would suggest a possible presence of some hormone precursor(s) inside the melanoma tumours. 相似文献
4.
5.
From sampling in three areas neighbouring Tunis, the first polluted, the second contaminated and the third clean, the authors point out that the technic of multiple samples using the "Lactose Broth" is the most sensible to faecal pollution. 相似文献
6.
L E Maroun 《The Biochemical journal》1979,179(1):221-225
Antiviral and cell-growth-inhibitory activities of human interferon were shown to be related to the activity of a gene or genes present on chromosome 21. The 18s rRNA is vital to cell growth; it is capable of a viral-mRNA-recognition function and it is coded for by genes a portion of which are present on chromosome-21. A previously reported ability of human interferon to affect rRNA metabolism is characterized by a decrease in the sucrose-gradient-peak ratio of radiolabelled 28S to 18S rRNA in extracts from the cytoplasm of interferon-treated human fibroblasts. In the present report, interferon dose-response curves are presented demonstrating a direct relationship between a decrease in this ratio and interferon concentrations in the media. By using this virus-independent cytoplasmic rRNA assay, eight human fibroblast lines, differing in chromosome 21 ploidy, were tested for sensitivity to human interferon. Two monosomy-21, two euploid-21 and four trisomy-21 cell lines were tested. The monosomy-21 cell populations were significantly less sensitive to interferon than the other six cell types tested. Of the cell lines tested, the most sensitive, by a wide margin, was a trisomy-21 line. Trisomy-21 cell monolayer sensitivity, however, varied widely within the range from normal to supersensitive. These observations suggest that interferon's ability to affect rRNA metabolism is related to the activity of a gene or genes present on chromosome 21. 相似文献
7.
Co-aggregation of penicillin g acylase and polyionic polymers: an easy methodology to prepare enzyme biocatalysts stable in organic media 总被引:1,自引:0,他引:1
Wilson L Illanes A Abián O Pessela BC Fernández-Lafuente R Guisán JM 《Biomacromolecules》2004,5(3):852-857
A novel type of biocatalyst that combines the good properties of cross-linked enzyme aggregates (CLEAs) and hydrophilic microenvironments has been developed. Dextran sulfate- and polyethyleneimine-coated CLEAs of penicillin acylase (CLEA-GDP) were prepared by adding the polymers of different sizes before the precipitation stage of the enzyme. This study presents the development and optimization of a protocol to produce such a biocatalyst using penicillin acylase as a model. Experiments show that CLEA-GDPs have a highly increased stability in organic media. The average half-life of the preparations was much higher than standard CLEA without a microenvironment (CLEA-G), (e.g., more than 25-fold) in the presence of dioxane. However, their thermal stability was not increased, which leads to the conclusion that the stability of CLEA-GDPs in organic media is due to the hydrophilic microenvironment that surrounds the protein enzyme more than to a conformational stiffening effect. This is further supported by solvation experiments that show a preferential hydration of CLEA when polymers are used to coat the enzyme. CLEA-GDPs are clearly better than other biocatalysts in terms of solvent stability. 相似文献
8.
Michel Edmond Ghanem Cristina Mart��nez-And��jar Alfonso Albacete Hana Posp��?ilov�� Ian C. Dodd Francisco P��rez-Alfocea Stanley Lutts 《Journal of Plant Growth Regulation》2011,30(2):144-157
Mixed nitrate/ammonium fertilization can partially alleviate the negative effects of salinity on growth of some plant species
compared to all-nitrate or all-ammonium fertilization. To gain insights about the mechanisms involved, tomato (Solanum lycopersicum L. cv Moneymaker) plants were grown hydroponically for 3 weeks with two NO3
−/NH4
+ fertilization regimes (6/0.5 and 5/1.5; Ntotal = 6.5 mM) in the absence (control) or presence of salt stress (100 mM NaCl). Ammonium enrichment had no effect on growth
and other parameters under control conditions. Under salinity, however, ammonium enrichment improved shoot and root biomass
by 20% and maintained leaf PSII efficiency close to control levels. These changes were related to higher leaf K+, NO3
−, and NH4
+ concentrations and activities of the N-assimilatory enzymes glutamate synthase (GOGAT) and glutamine synthase (GS) in the
leaves. Ammonium enrichment also attenuated the salt-induced increase in leaf abscisic acid (ABA) concentration and decrease
in leaf concentrations of indole 3-acetic acid (IAA) and the cytokinins trans-zeatin (tZ) and trans-zeatin riboside (tZR). Enhanced cytokinin status was probably due to maintenance of root-to-shoot cytokinin transport and decreased leaf induction
of the cytokinin-degrading enzyme cytokinin oxidase/dehydrogenase (CKX) under ammonium-enriched conditions. It is concluded
that nitrogen form modifies salinity-induced physiological responses and that these modifications are associated with changes
in plant hormone status. 相似文献
9.
R G Maroun S Gayet M S Benleulmi H Porumb L Zargarian H Merad H Leh J F Mouscadet F Troalen S Fermandjian 《Biochemistry》2001,40(46):13840-13848
Integration of HIV-1 genome into host cell chromosome is mediated by viral integrase (IN). The IN catalytic core (CC, IN(50-212)) dimerizes through mutual interactions of its alpha1 and alpha5 helices. Peptides INH1 and INH5 reproducing these helix sequences strongly inhibited IN. For instance, an IC(50) of 80 nM was determined for INH5 in integration assays using wild-type IN (wtIN). In size exclusion chromatography, INH1 and INH5 perturbed the association-dissociation equilibrium of both dmIN (IN(1-288)/F185K/C280S) and CC, leading to monomers as surviving species, while in circular dichroism, binding of peptides to dmIN altered the protein conformation. Thus, enzyme deactivation, subunit dissociation, and protein unfolding are events which parallel one another. The target of INH5 in the enzyme was then identified. In fluorescence spectroscopy, C(0.5) values of 168 and 44 nM were determined for the binding affinity of INH5 to IN and CC, respectively, at 115 nM subunit concentration, while interaction of INH5 with INH1 was found stronger than interaction of INH5 with itself (23 times larger in term of dissociation constants). These results strongly suggested that the alpha1 helix is the privileged target of INH5. The latter could serve as a lead for the development of new chemotherapeutic agents against HIV-1. 相似文献
10.
Numerous reports have demonstrated that specific protein synthesis in response to specific inducers is markedly stimulated by a simultaneous brief exposure to protein synthesis inhibitors such as cycloheximide. This phenomenon is known as “superinduction” and is most often attributed to the accumulation of cytoplasmic messenger RNA during the inhibition period. Messenger RNA, as defined by rapid labeling, oligo (dt)-cellulose binding, and cell free protein synthesis stimulation was measured in cycloheximide treated human fibroblasts. In spite of a consistent 40% decrease in total polysomal 3H-uridine labeled RNA, a 1.5- to 2-fold increase in extractable mRNA was observed. These data provide direct evidence that protein synthesis inhibition stimulates the appearance of cytoplasmic mRNA and/or completely blocks its degradation and, are consistent with the hypothesis that mRNA accumulation partly underlies the superinduction phenomena. 相似文献