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21.
Rachida Yahiaoui Abdelhadi Guechi Emilie Lukasova Prof. Loïc Girre 《Mycopathologia》1994,126(2):121-129
A phytotoxic substance (C23H44O3) which is named Substance A, was purified from olive leaves infected withCycloconium oleaginum Cast. The mutagenic effect of this substance was detected using TA 100 and TA 102 strains ofSalmonella in the Ames test usingBacillus subtilis strains M45 rec–, H17 rec+ in the rec assay. Another substance manifesting the mutagenic effect was found in the extract from theCycloconium oleaginum culture. This substance was not detected in the extract from contaminated olive leaves. Substance A increased electrolytes leakage from tissue of olive leaves, thus manifesting its phytotoxicity. 相似文献
22.
Depret G Houot S Allard MR Breuil MC Nouaïm R Laguerre G 《FEMS microbiology ecology》2004,51(1):87-97
Little is known about factors that affect the indigenous populations of rhizobia in soils. We compared the abundance, diversity and genetic structure of Rhizobium leguminosarum biovar viciae populations in soils under different crop managements, i.e., wheat and maize monocultures, crop rotation, and permanent grassland. Rhizobial populations were sampled from nodules of pea- or vetch plants grown in soils collected at three geographically distant sites in France, each site comprising a plot under long-term maize monoculture. Molecular characterization of isolates was performed by PCR-restriction fragment length polymorphism of 16S-23S rDNA intergenic spacer as a neutral marker of the genomic background, and PCR-restriction fragment length 0polymorphism of a nodulation gene region, nodD, as a marker of the symbiotic function. The diversity, estimated by richness in types and Simpson's index, was consistently and remarkably lower in soils under maize monoculture than under the other soil managements at the three sites, except for the permanent grassland. The highest level of diversity was found under wheat monoculture. Nucleotide sequences of the main rDNA intergenic spacer types were determined and sequence analysis showed that the prevalent genotypes in the three maize fields were closely related. These results suggest that long-term maize monoculturing decreased the diversity of R. leguminosarum biovar viciae populations and favored a specific subgroup of genotypes, but the size of these populations was generally preserved. We also observed a shift in the distribution of the symbiotic genotypes within the populations under maize monoculture, but the diversity of the symbiotic genotypes was less affected than that of IGS types. The possible effect of such changes on biological nitrogen fixation remains unknown and this requires further investigation. 相似文献
23.
The expression of the NADPH oxidase subunit p22phox is regulated by a redox-sensitive pathway in endothelial cells 总被引:7,自引:0,他引:7
Djordjevic T Pogrebniak A BelAiba RS Bonello S Wotzlaw C Acker H Hess J Görlach A 《Free radical biology & medicine》2005,38(5):616-630
Endothelial dysfunction is characterized by increased levels of reactive oxygen species (ROS) and a prothrombotic state. The mechanisms linking thrombosis to ROS production in the endothelium are not well understood. We investigated the role of thrombin in regulating NADPH oxidase-dependent ROS production and expression of its subunit p22phox in the endothelial cell line EaHy926. Thrombin elicited a biphasic increase in ROS generation peaking within 15 min, but also at 3 h. The delayed response was accompanied by increased p22phox mRNA and protein expression. Two-photon confocal laser microscopy showed colocalization between p22phox and ROS production. Antioxidant treatment with vitamin C or diphenyleneiodonium abrogated thrombin-induced ROS production and p22phox expression, whereas H2O2 elevated ROS production and p22phox levels. Both responses were dependent on p38 MAP kinase and phosphatidylinositol-3-kinase (PI3 kinase)/Akt. Finally, p22phox was required for thrombin- or H2O2-stimulated proliferation. These data show that thrombin rapidly increases ROS production in endothelial cells, resulting, via activation of p38 MAP kinase and PI3 kinase/Akt, in upregulation of p22phox accompanied by a delayed increase in ROS generation and enhanced proliferation. These findings suggest a positive feedback mechanism whereby ROS, possibly generated by the NADPH oxidase, lead to elevated levels of p22phox and, thus, sustained ROS generation as is observed in endothelial dysfunction. 相似文献
24.
Synthesis of 3'-3', 5-5', and 3'-5' dimeric thymidine, linked by an olefinic chain between glycosidic moieties is described. Cross metathesis reaction of 3' or 5' O-allyl analogues of thymidine led to the expected 3'-3' and 5'-5' dimeric compounds, respectively. In order to obtain the 3'-5' dimer, 5'-O-allyl and 3'-O-allyl monomers were first linked by their free 3' OH and 5' OH groups through a glutaryl spacer; ring closing metathesis was then operated upon this temporary dimer, followed by glutaryl removal. 相似文献
25.
26.
Roberta J. Ward Stephanie Wilmet Rachida Legssyer Daniel Leroy Louise Toussaint Robert R. Crichton Christophe Pierreux Louis Hue Jacques Piette Surjit Kaila Srai Nita Solanky Dominique Klein Karl Summer 《Biometals》2009,22(2):211-223
The effects of changes in macrophage iron status, induced by single or multiple iron injections, iron depletion or pregnancy,
on both immune function and mRNA expression of genes involved in iron influx and egress have been evaluated. Macrophages isolated
from iron deficient rats, or pregnant rats at day 21 of gestation, either supplemented with a single dose of iron dextran,
10 mg, at the commencement of pregnancy, or not, showed significant increases of macrophage ferroportin mRNA expression, which was paralleled by significant decreases in hepatic Hamp mRNA expression. IRP activity in macrophages was not significantly altered by iron status or the inducement of pregnancy
± a single iron supplement. Macrophage immune function was significantly altered by iron supplementation and pregnancy. Iron
supplementation, alone or combined with pregnancy, increased the activities of both NADPH oxidase and nuclear factor kappa
B (NFκB). In contrast, the imposition of pregnancy reduced the ability of these parameters to respond to an inflammatory stimuli.
Increasing iron status, if only marginally, will reduce the ability of macrophages to mount a sustained response to inflammation
as well as altering iron homeostatic mechanisms. 相似文献
27.
Ludovic Colombeau Karine Teste Amel Hadj-Bouazza Vincent Chaleix Rachida Zerrouki Michel Kraemer 《Nucleosides, nucleotides & nucleic acids》2013,32(2):110-120
The synthesis and biological activity of chloroethyl pyrimidine nucleosides is presented. One of these new nucleosides analogues significantly inhibited cell proliferation, migration and invasion as tested in vitro on the A431 vulvar epidermal carcinoma cell line. 相似文献
28.
Antoine Adenis Mathieu Nacher Matthieu Hanf Vincent Vantilcke Rachida Boukhari Denis Blachet Magalie Demar Christine Aznar Bernard Carme Pierre Couppie 《PLoS neglected tropical diseases》2014,8(8)
Background
Histoplasmosis is an endemic fungal infection in French Guiana. It is the most common AIDS-defining illness and the leading cause of AIDS-related deaths. Diagnosis is difficult, but in the past 2 decades, it has improved in this French overseas territory which offers an interesting model of Amazonian pathogen ecology. The objectives of the present study were to describe the temporal trends of incidence and mortality indicators for HIV-associated histoplasmosis in French Guiana.Methods
A retrospective study was conducted to describe early mortality rates observed in persons diagnosed with incident cases of HIV-associated Histoplasma capsulatum var. capsulatum histoplasmosis admitted in one of the three main hospitals in French Guiana between 1992 and 2011. Early mortality was defined by death occurring within 30 days after antifungal treatment initiation. Data were collected on standardized case report forms and analysed using standard statistical methods.Results
There were 124 deaths (45.3%) and 46 early deaths (16.8%) among 274 patients. Three time periods of particular interest were identified: 1992–1997, 1998–2004 and 2005–2011. The two main temporal trends were: the proportion of early deaths among annual incident histoplasmosis cases significantly declined four fold (χ2, p<0.0001) and the number of annual incident histoplasmosis cases increased three fold between 1992–1997 and 1998–2004, and subsequently stabilized.Conclusion
From an occasional exotic diagnosis, AIDS-related histoplasmosis became the top AIDS-defining event in French Guiana. This was accompanied by a spectacular decrease of early mortality related to histoplasmosis, consistent with North American reference center mortality rates. The present example testifies that rapid progress could be at reach if awareness increases and leads to clinical and laboratory capacity building in order to diagnose and treat this curable disease. 相似文献29.
Naima Taqarort Abdelouahed Echairi Remi Chaussod Rachida Nouaim Hassan Boubaker Abdellah A. Benaoumar Elhassan Boudyach 《World journal of microbiology & biotechnology》2008,24(12):3031-3038
Epiphytic yeasts isolated from the surface of citrus fruits, harvested in several orchards in the Souss-Massa-Draa Valley,
Agadir, Morocco, were in vivo screened for antagonistic activity against Penicillium digitatum, the causal agent of green mold of citrus. From a total of 245 yeast strains assessed for their biocontrol activity against
P. digitatum, fifteen reduced the incidence of disease to less than 50%. The effectiveness of the best selected yeast strains showed that
Pichia anomala (YT73), Debaryomyces hansenii (YT22) and Hanseniaspora guilliermondii (YT13) were the most effective, with a reduction of green mold incidence from 65 to ~80%, compared to the control. The identification
of the fifteen selected yeast strains was carried out through an integrated approach including phenotypic and genotypic (sequencing
of D1/D2 domain of 26S rDNA encoding gene) methods. These 15 selected were identified as: H. guilliermondii, D. hansenii, H. uvarum and P. anomala. The study of the dynamics of two of the best strains, H. guilliermondii and D. hansenii, showed that these strains can grow rapidly, by approximately 2 log units, in citrus fruit wounds. Such rapid growth in wounds
indicates that these antagonist yeasts are excellent colonizers of citrus wounds and can thrive on citrus fruits as a substrate. 相似文献
30.
Abes R Moulton HM Clair P Yang ST Abes S Melikov K Prevot P Youngblood DS Iversen PL Chernomordik LV Lebleu B 《Nucleic acids research》2008,36(20):6343-6354
Redirecting the splicing machinery through the hybridization of high affinity, RNase H- incompetent oligonucleotide analogs such as phosphoramidate morpholino oligonucleotides (PMO) might lead to important clinical applications. Chemical conjugation of PMO to arginine-rich cell penetrating peptides (CPP) such as (R-Ahx-R)4 (with Ahx standing for 6-aminohexanoic acid) leads to sequence-specific splicing correction in the absence of endosomolytic agents in cell culture at variance with most conventional CPPs. Importantly, (R-Ahx-R)4–PMO conjugates are effective in mouse models of various viral infections and Duchenne muscular dystrophy. Unfortunately, active doses in some applications might be close to cytotoxic ones thus presenting challenge for systemic administration of the conjugates in those clinical settings. Structure–activity relationship studies have thus been undertaken to unravel CPP structural features important for the efficient nuclear delivery of the conjugated PMO and limiting steps in their internalization pathway. Affinity for heparin (taken as a model heparan sulfate), hydrophobicity, cellular uptake, intracellular distribution and splicing correction have been monitored. Spacing between the charges, hydrophobicity of the linker between the Arg-groups and Arg-stereochemistry influence splicing correction efficiency. A significant correlation between splicing correction efficiency, affinity for heparin and ability to destabilize model synthetic vesicles has been observed but no correlation with cellular uptake has been found. Efforts will have to focus on endosomal escape since it appears to remain the limiting factor for the delivery of these splice-redirecting ON analogs. 相似文献