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991.
Roads have many effects on the mammal populations of their surroundings. Prey species are thought to establish dense populations in road verges due to a predation release effect, which arise as a side-effect of roadside avoidance by predators and/or predator roadkill. A species that has been suggested to benefit from predation release and attain high densities near roads is the European rabbit, a keystone species in Mediterranean ecosystems. We monitored rabbit relative abundance at three distances from a motorway (50, 450 and 850 m) during a 6 month period, as well as hunting and predator pressures, in a suitable area for rabbits. The lowest rabbit abundance was found next to the motorway (6.76 ± 8.87 pellets/m2 per month) and the highest abundance at an intermediate distance (17.65 ± 23.11 pellets/m2 per month). Hunting and carnivore pressures were highest at the sampling transect located farthest from the infrastructure. Thus, variability in rabbit abundance did not match the predation release effect found close to the motorway, and some sort of road avoidance or other process must underlie the observed abundance pattern. We advocate for a formal measurement of prey populations response to roads prior to any generalization as, in the case of rabbit, the response to roads and the potential cascading effects on other species may depend on landscape characteristics.  相似文献   
992.
Crude glycerol is a primary by‐product in the biodiesel industry. Microbial fermentation on crude glycerol for producing value‐added products provides opportunities to utilize a large quantity of this by‐product. This study investigates the potential of using the crude glycerol to produce vancomycin (glycopeptide antibiotics) through fermentation of Amycolatopsis orientalis XMU‐VS01. The results show that crude glycerol was the most effective carbon source for mycelium growth and vancomycin production, with 40–60 g/L glycerol concentration as optimal range. Among other culture medium components, potato protein (nitrogen source) and the phosphate concentration had significant effects (p<0.05) for vancomycin production. A Box‐Behnken design and response surface methodology were employed to formulate the optimal medium. Their optimal values were determined as 52.73 g/L of glycerol, 17.36 g/L of potato protein, and 0.1 g/L of dipotassium phosphate. A highest vancomycin yield of 7.61 g/L with biomass concentration of 15.8 g/L was obtained after 120 h flask fermentation. The yield of vancomycin was 3.5 times higher than with basic medium. The results suggest that biodiesel‐derived crude glycerol is a promising feedstock for production of vancomycin from A. orientalis culture.  相似文献   
993.
994.
熊娟  赵玲  江道龙  朱琳  杨霜 《生物磁学》2013,(30):5962-5964
目的:分析重度妊娠期肝内胆汁淤积症(intrahepatic cholestasis of pregnancy,ICP)对母婴结局的影响,以提高对ICP的认识与治疗水平。方法:选择ICP产妇58例,根据ICP分度标准分为轻度组(n=26例)和重度组(n=32例),比较两组产妇的母婴结局。结果:与轻度组相比,重度组产妇剖宫产率、产后出血与平均产后出血量显著升高或增加,阴道分娩率显著降低,组间比较差异均具有统计学意义(P〈0.05);重度组新生儿早产、胎儿窘迫、羊水污染和新生儿窒息的发生率均显著上升,新生儿平均出生体重显著降低,组间比较差异均具有统计学意义(P〈0.05)。结论:ICP对产妇及新生儿均有不良影响,对ICP严重程度进行划分,有利于临床处理。对于重度ICP产妇,应尽早采取剖宫产分娩的方式终止妊娠。  相似文献   
995.
Intrinsic properties of surface plasmons (SPs) excited with Kretschmann configuration were analyzed as a function of wavelength, including the propagation length, the penetration depth, the Goos–Hänchen (GH) shift, and the field enhancement. The calculated results indicate that there exists a critical thickness (t cr) of the gold layer and that the maximum GH shift occurring exactly at the SP resonance wavelength (λ R) rapidly varies from positive to negative with changing of the gold layer thickness from t?<?t cr to t?>?t cr. The maximum field enhancement happens not at λ R but at a wavelength smaller than λ R due to the phase retardation between the transmitted and reflected light. Simulations also reveal that a broadband collimated near-infrared beam can simultaneously excite two SPs with different responses to a refractive index (RI) change: the shorter-wavelength SP able to make a small redshift and the longer-wavelength SP capable of yielding a large blueshift. Only the shorter-wavelength SP was experimentally observed and its RI sensitivity was measured to increase from 3,539 nm/RIU at λ R?=?707.6 nm to 57,143 nm/RIU at λ R?=?1,398 nm. The SP at λ R?=?1,013 nm moved to λ R?=?1,029 nm in response to the saturation adsorption of bovine serum albumin, and the corresponding surface coverage was determined to be Γ?=?1.565 ng/mm2 based on a quasilinear dependence of Γ on the resonance wavelength shift (?λ R) deduced theoretically. Butyrylcholinesterase adsorption from a dilute solution of 10 nM protein in phosphate buffer solution leads to a redshift of ?λ R?=?10 nm, corresponding to Γ?≈?0.97 ng/mm2.  相似文献   
996.
In view of synergistic effect of resveratrol and insulin in the prevention and treatment of many chronic diseases, the interaction between them was studied and its biological implication was further discussed. Insulin could interact with resveratrol to form 1:1 complex with the binding constant of 1.03?×?103 M?1 at 298 K. The binding was spontaneous and insulin/resveratrol complex formation was an exothermal reaction. Hydrogen bond and van der Waals force played key roles in the binding process. Kinetic study indicates that resveratrol binding to insulin conformed to the first-order exponential decay function. The interaction decreased the polarity around tyrosine residue and α-helical content, destroyed the disulfide bridges, depolymerized insulin dimers to monomer, and altered the orientation of aromatic side chains in the insulin. Additionally, insulin increased resveratrol stability. These results well confirm synergistic effect of resveratrol and insulin in vitro. It would give a deeper insight into resveratrol as a kind of food functional factor.  相似文献   
997.
Herein, a flexible surface-enhanced Raman spectroscopy (SERS) substrate composed of nanodot-arrayed Ag film and Ag nanocubes was fabricated through a simple method. The large-area nanodot-arrayed Ag film was produced at low cost and high reproducibility. The experimental results show that the coupled structure produces a much stronger SERS signal than the Ag nanocube alone and the isolated nanodot-arrayed Ag film. Furthermore, the coupling effect is sensitive to geometrical parameter of the period of the dot-array. Numerical simulations are performed to verify the electric field enhancement of the composite SERS substrate and support the experimental results.  相似文献   
998.
Recently, it has been suggested that C2ORF40 is a candidate tumor suppressor gene in breast cancer. However, the mechanism for reduced expression of C2ORF40 and its functional role in breast cancers remain unclear. Here we show that C2ORF40 is frequently silenced in human primary breast cancers and cell lines through promoter hypermethylation. C2ORF40 mRNA level is significantly associated with patient disease-free survival and distant cancer metastasis. Overexpression of C2ORF40 inhibits breast cancer cell proliferation, migration and invasion. By contrast, silencing C2ORF40 expression promotes these biological phenotypes. Bioinformatics and FACS analysis reveal C2ORF40 functions at G2/M phase by downregulation of mitotic genes expression, including UBE2C. Our results suggest that C2ORF40 acts as a tumor suppressor gene in breast cancer pathogenesis and progression and is a candidate prognostic marker for this disease.  相似文献   
999.
The initiation of angiogenesis can mark the transition from tumor dormancy to active growth and recurrence. Mechanisms that regulate recurrence in human cancers are poorly understood, in part because of the absence of relevant models. The induction of ARHI (DIRAS3) induces dormancy and autophagy in human ovarian cancer xenografts but produces autophagic cell death in culture. The addition of VEGF to cultures maintains the viability of dormant autophagic cancer cells, thereby permitting active growth when ARHI is downregulated, which mimics the “recurrence” of growth in xenografts. Two inducible ovarian cancer cell lines, SKOv3-ARHI and Hey-ARHI, were used. The expression level of angiogenesis factors was evaluated by real-time PCR, immunohistochemistry, immunocytochemistry and western blot; their epigenetic regulation was measured by bisulfite sequencing and chromatin immunoprecipitation. Six of the 15 angiogenesis factors were upregulated in dormant cancer cells (tissue inhibitor of metalloproteinases-3, TIMP3; thrombospondin-1, TSP1; angiopoietin-1; angiopoietin-2; angiopoietin-4; E-cadherin, CDH1). We found that TIMP3 and CDH1 expression was regulated epigenetically and was related inversely to the DNA methylation of their promoters in cell cultures and in xenografts. Increased H3K9 acetylation was associated with higher TIMP3 expression in dormant SKOv3-ARHI cells, while decreased H3K27me3 resulted in the upregulation of TIMP3 in dormant Hey-ARHI cells. Elevated CDH1 expression during dormancy was associated with an increase in both H3K4me3 and H3K9Ac in two cell lines. CpG demethylating agents and/or histone deacetylase inhibitors inhibited the re-growth of dormant cancer cells, which was associated with the re-expression of anti-angiogenic genes. The expression of the anti-angiogenic genes TIMP3 and CDH1 is elevated during dormancy and is reduced during the transition to active growth by changes in DNA methylation and histone modification.  相似文献   
1000.
DNA methylation changes are known to occur in gastric cancers and in premalignant lesions of the gastric mucosae. In order to examine variables associated with methylation levels, we quantitatively evaluated DNA methylation in tumors, non-tumor gastric mucosae, and in gastric biopsies at promoters of 5 genes with methylation alterations that discriminate gastric cancers from non-tumor epithelia (EN1, PCDH10, RSPO2, ZIC1, and ZNF610). Among Colombian subjects at high and low risk for gastric cancer, biopsies from subjects from the high-risk region had significantly higher levels of methylation at these 5 genes than samples from subjects in the low risk region (p ≤ 0.003). When results were stratified by Helicobacter pylori infection status, infection with a cagA positive, vacA s1m1 strain was significantly associated with highest methylation levels, compared with other strains (p = 0.024 to 0.001). More severe gastric inflammation and more advanced precancerous lesions were also associated with higher levels of DNA methylation (p ≤ 0.001). In a multivariate model, location of residence of the subject and the presence of cagA and vacA s1m1 in the H. pylori strain were independent variables associated with higher methylation in all 5 genes. High levels of mononuclear cell infiltration were significantly related to methylation in PCDH10, RSPO2, and ZIC1 genes. These results indicate that for these genes, levels of methylation in precancerous lesions are related to H. pylori virulence, geographic region and measures of chronic inflammation. These genes seem predisposed to sustain significant quantitative changes in DNA methylation at early stages of the gastric precancerous process.  相似文献   
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