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排序方式: 共有118条查询结果,搜索用时 15 毫秒
21.
Pascale Simard Hugo Galarneau Sébastien Marois Daniel Rusu Caroline D Hoemann Patrice E Poubelle Hani El-Gabalawy Maria JG Fernandes 《Arthritis research & therapy》2009,11(3):R74-10
Introduction
Osteoarthritis is characterized by the progressive destruction of cartilage in the articular joints. Novel therapies that promote resurfacing of exposed bone in focal areas are of interest in osteoarthritis because they may delay the progression of this disabling disease in patients who develop focal lesions. Recently, the addition of 80% deacetylated chitosan to cartilage microfractures was shown to promote the regeneration of hyaline cartilage. The molecular mechanisms by which chitosan promotes cartilage regeneration remain unknown. Because neutrophils are transiently recruited to the microfracture site, the effect of 80% deacetylated chitosan on the function of neutrophils was investigated. Most studies on neutrophils use preparations of chitosan with an uncertain degree of deacetylation. For therapeutic purposes, it is of interest to determine whether the degree of deacetylation influences the response of neutrophils to chitosan. The effect of 95% deacetylated chitosan on the function of neutrophils was therefore also investigated and compared with that of 80% deacetylated chitosan. 相似文献22.
应用红外相机技术研究秦岭观音山自然保护区内野猪的行为和丰富度 总被引:1,自引:0,他引:1
2009年7月,在陕西观音山自然保护区凉风垭小区域(中高海拔)和西沟小区域(低海拔)安装18台红外相机,2009年8月至2013年4月共收集野猪照片1 195张。定义9种野猪行为,分别为站立、走动、跑动、采食、饮水、修饰、发情、拱土、坐着休息,并逐一比对照片中野猪的行为,统计各种行为所占的比例;引入月相对丰富度和时间段相对丰富度两个指数分别研究野猪的年活动规律和日活动规律;利用一个种群估测模型探讨野猪密度的年际变化。结果表明:(1)春季野猪以走动、采食和站立为主,分别占总行为次数的36%、25.6%和17.4%;夏季野猪以走动、站立、采食和跑动为主,分别占总行为次数的35.7%、23.6%、17%和16.5%;秋季野猪以采食、走动和发情为主,分别占总行为次数的50.3%、19.3%和17.8%;冬季野猪以采食、走动和站立为主,分别占总行为次数的53.7%、26.7%和11.9%。(2)野猪在8月、9月和12月活动较为频繁;全年日活动高峰出现在午后14:00-16:00,低谷出现在22:00-04:00,四季显示活动规律不同。(3)2009-2012年野猪密度呈逐年上升趋势。这些研究结果有助于了解野猪的行为活动和种群动态,并采取针对性的措施对野猪进行有效管理。 相似文献
23.
The minimum inhibitory concentration (MIC) of eight antimicrobial agents was determined by the agar dilution method for 80 isolates of Clostridium difficile from neonatal pigs with enteritis. MICs(50) for erythromycin, tilmicosin, and tylosin were relatively low (0.25-0.50 microg/mL), but MICs(90) (64 or > or =256 microg/mL) suggest in vivo resistance of a proportion of isolates. Susceptibility to tetracycline varied widely, with MIC(50) and MIC(90) of 8 and 32 microg/mL, respectively. The MICs(90) for tiamulin (8 microg/mL) and virginiamycin (16 microg/mL) suggest moderate susceptibility. Bacitracin and ceftiofur (MICs(90) > or =256 microg/mL) have little activity against C. difficile. Tiamulin and virginiamycin may decrease fecal shedding of C. difficile by sows, and erythromycin, tetracycline, and tylosin may be useful for treatment of infected piglets. 相似文献
24.
The plo gene, encoding the Arcanobacterium pyogenes cholesterol-dependent cytolysin, pyolysin (PLO), was localized to a 2.7-kb genomic islet of reduced %G+C content and alternate codon usage frequency. This islet, conserved among isolates from diverse hosts and geographical locations, separated the housekeeping genes smc and ftsY, which are found adjacent in many prokaryotes. The ftsY and ffh genes, located downstream of the plo islet, encode components of the signal recognition particle. Mutational analysis suggested that these genes were essential for viability in A. pyogenes. The A. pyogenes ffh gene was unable to complement a conditional ffh mutant of Escherichia coli and its overexpression was toxic in E. coli. Mutagenesis of the islet-encoded orf121 did not affect plo expression, indicating that it may not be involved directly in the regulation of plo expression. Regardless, the presence of the plo gene as part of a genomic islet inserted between genes essential for normal growth may provide selective pressure for the retention of this important virulence factor. 相似文献
25.
Purification and characterization of Dolichos lablab lectin 总被引:1,自引:0,他引:1
The mannose/glucose-binding Dolichos lablab lectin (designated DLL) has
been purified from seeds of Dolichos lablab (hyacinth bean) to
electrophoretic homogeneity by affinity chromatography on an ovalbumin-
Sepharose 4B column. The purified lectin gave a single symmetric protein
peak with an apparent molecular mass of 67 kDa on gel filtration
chromatography, and five bands ranging from 10 kDa to 22 kDa upon SDS-PAGE.
N-Terminal sequence analysis of these bands revealed subunit heterogeneity
due to posttranslational proteolytic truncation at different sites mostly
at the carboxyl terminus. The carbohydrate binding properties of the
purified lectin were investigated by three different approaches:
hemagglutination inhibition assay, quantitative precipitation inhibition
assay, and ELISA. On the basis of these studies, it is concluded that the
Dolichos lablab lectin has neither an extended carbohydrate combining site,
nor a hydrophobic binding site adjacent to it. The carbohydrate combining
site of DLL appears to most effectively accommodate a nonreducing terminal
alpha-d-mannosyl unit, and to be complementary to the C-3, C-4, and C-6
equatorial hydroxyl groups of alpha-d-mannopyranosyl and
alpha-d-glucopyranosyl residues. DLL strongly precipitates murine IgM but
not IgG, and the recent finding that this lectin interacts specifically
with NIH 3T3 fibroblasts transfected with the Flt3 tyrosine kinase receptor
and preserves human cord blood stem cells and progenitors in a quiescent
state for prolonged periods in culture, make this lectin a valuable tool in
biomedical research.
相似文献
26.
27.
Cecilia JG de Almeida Jean-Fran?ois Jasmin Francesco Del Galdo Michael P Lisanti 《Cell cycle (Georgetown, Tex.)》2013,12(14):2248-2254
Caveolar domains act as platforms for the organization of molecular complexes involved in signal transduction. Caveolin proteins, the principal structural components of caveolae, have been involved in many cellular processes. Caveolin-1 (Cav-1) and caveolin-2 (Cav-2) are highly expressed in the lung. Cav-1-deficient mice (Cav-1−/−) and Cav-2-deficient mice (Cav-2−/−) exhibit severe lung dysfunction attributed to a lack of Cav-2 expression. Recently, Cav-1 has been shown to regulate lung fibrosis in different models. Here, we show that Cav-2 is also involved in modulation of the fibrotic response, but through distinct mechanisms. Treatment of wild-type mice with the pulmonary fibrosis-inducer bleomycin reduced the expression of Cav-2 and its phosphorylation at tyrosine 19. Importantly, Cav-2−/− mice, but not Cav-1−/− mice, were more sensitive to bleomycin-induced lung injury in comparison to wild-type mice. Bleomycin-induced lung injury was characterized by alveolar thickening, increase in cell density, and extracellular matrix deposition. The lung injury observed in bleomycin-treated Cav-2−/− mice was not associated with alterations in the TGF-β signaling pathway and/or in the ability to produce collagen. However, apoptosis and proliferation were more prominent in lungs of bleomycin-treated Cav-2−/− mice. Since Cav-1−/− mice also lack Cav-2 expression and show a different outcome after bleomycin treatment, we conclude that Cav-1 and Cav-2 have distinct roles in bleomycin induced-lung fibrosis, and that the balance of both proteins determines the development of the fibrotic process. 相似文献
28.
Two distinct conformational states define the interaction of human RAD51‐ATP with single‐stranded DNA 下载免费PDF全文
Andrea Candelli Edwige B Garcin Mauro Modesti Luca Pellegrini Gijs JL Wuite Erwin JG Peterman 《The EMBO journal》2018,37(7)
An essential mechanism for repairing DNA double‐strand breaks is homologous recombination (HR). One of its core catalysts is human RAD51 (hRAD51), which assembles as a helical nucleoprotein filament on single‐stranded DNA, promoting DNA‐strand exchange. Here, we study the interaction of hRAD51 with single‐stranded DNA using a single‐molecule approach. We show that ATP‐bound hRAD51 filaments can exist in two different states with different contour lengths and with a free‐energy difference of ~4 kBT per hRAD51 monomer. Upon ATP hydrolysis, the filaments convert into a disassembly‐competent ADP‐bound configuration. In agreement with the single‐molecule analysis, we demonstrate the presence of two distinct protomer interfaces in the crystal structure of a hRAD51‐ATP filament, providing a structural basis for the two conformational states of the filament. Together, our findings provide evidence that hRAD51‐ATP filaments can exist in two interconvertible conformational states, which might be functionally relevant for DNA homology recognition and strand exchange. 相似文献
29.
The procedures and equipment needed to measure filtration efficiency by means of fluorescent aerosols are described. The filtration efficiency of individual lots of spun-glass air filtration medium or of entire air filtration systems employing such media was determined. Data relating to the comparative evaluation of spun-glass filter media by means of the fluorometric method described, as well as by conventional biological procedures, are presented. 相似文献
30.
The alcohol dehydrogenase (Adh) region from five planitibia subgroup
species of Hawaiian picture-wing Drosophila has been cloned. A total of 15
kb of DNA in and around the Adh gene has been compared among the five
species. Genetic distances were calculated to determine evolutionary
relationships. These distances agree with previous distances determined by
protein polymorphism and DNA hybridization techniques and can be
interpreted in terms of specific island colonization and speciation
(founder) events over the past 5 Myr. Examination of the restriction maps
of the cloned Adh region from the five species shows many instances of
small deletions, insertion of a transposable element in D. heteroneura, and
the existence of a highly variable region on the 3' side of the Adh gene.
Clustering relationships and rates of DNA change are calculated and
compared with the relationship found for other species of Drosophila.
相似文献