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991.
Enantiomeric amphipathic α-helical antibacterial peptides were synthesized and their biophysical and biological properties under different physiological conditions were studied. In the absence of physiological factors, the l- and d-peptides exhibited similar antimicrobial activities against a broad spectrum of bacteria, even against clinical isolates with resistance to traditional antibiotics. However, in the presence of NaCl, CaCl2 or human serum albumin (HSA) at physiological concentrations, the enantiomers revealed bacterium-species dependent attenuations in antibacterial activity. In the presence of salts the electrostatic interaction between the peptides and the biomembrane was inhibited. Salts, especially CaCl2, weakened the ability of the peptides to permeabilize the outer membrane of Gram-negative bacteria, as determined by a 1-N-phenylnaphthylamine uptake assay. HSA exhibited variable inhibitory effects on the activity of the peptides when incubated with different bacterial strains. The peptides showed different binding association abilities to HSA at different molar ratios, regardless of their chirality, resulting in reduced peptide biological activity. The d-peptide performed better than its l-enantiomer in all conditions tested because of its resistance to proteolysis, and may therefore represent a promising candidate for development as a therapeutic agent. 相似文献
992.
A versatile and highly sensitive probe for Hg(II), Pb(II) and Cd(II) detection individually and totally in water samples 总被引:1,自引:0,他引:1
Zhou Y Tian XL Li YS Zhang YY Yang L Zhang JH Wang XR Lu SY Ren HL Liu ZS 《Biosensors & bioelectronics》2011,30(1):310-314
The detection of heavy metal ions using enzyme-linked immunosorbent assays (ELISA) has been reported by several research groups. However, highly sensitive and selective detection of total heavy metal ions using ELISA is a major technical limitation. Here we describe the development of a versatile and highly sensitive probe combining goat anti-mice IgG, colloidal gold nanoparticles (AuNPs) and horseradish peroxidase (HRP). We demonstrate the utility of this probe using three kinds of heavy metal complete antigens and three monoclonal antibodies (McAbs) in one ELISA system to establish a high-throughput screening protocol. The procedure was successfully applied to analysis of Hg(II), Pb(II) and Cd(II) individually and totally from different water samples. The sensitivities for the detection of Hg(II), Pb(II) and Cd(II) individually and totally are 27.4, 3.9, 15.8 and 18.2 nM, respectively. And all limit of detection (LODs) are lower than 1.2 nM. The recovery results obtained from the developed technique showed a good correlation (R2 = 0.983) with those from ICP-MS. The major advantage of the probe is the versatility and high sensibility. The probe could be potentially used, upon demand, as a sensitive and versatile detector for a broad range of applications. 相似文献
993.
提出顶点及顶点相互作用矢量的概念,并将该矢量用于复杂样本的分子结构表征。采用逐步回归结合统计检测对变量进行筛选后,再用多元线性回归建立了定量结构-色谱保留(QSRR)关系的7变量模型,模型的建模计算值复相关系数(R)为0.990,标准偏差(SD)为1.325;留一法(LOO)交互检验复相关系数(RCV)为0.983,标准偏差(SDCV)为1.696。结果表明该矢量具有较强的分子结构表达能力,模型具有良好的估计能力与稳定性。 相似文献
994.
目的探讨p16和Ki67在非小细胞肺癌(non-small cell lung cancer,NSCLC)中的表达,研究它们对NSCLC患者预后的影响及其与临床及病理因素之间的关系。方法收集NSCLC术后标本160例及正常肺组织20例(对照组),应用免疫组化法检测NSCLC组织和正常肺组织中p16和Ki67的表达。结果在NSCLC组织和正常肺组织中,p16和Ki67的阳性表达率分别为23.8%、82.5%和90%、5%,差异有统计学意义(P〈0.05)。多因素分析:PTNM分期、淋巴结转移、p16及Ki67的表达是影响NSCLC根治术后患者预后的独立因素(P〈0.05);p16阳性组与阴性组5年生存率分别为55.3%和18.0%,差异有统计学意义(P〈0.05);Ki67阳性组与阴性组5年生存率分别为23.5%和42.9%,差异有统计学意义(P〈0.05),p16和Ki67表达呈负相关(P〈0.05)。结论 p16和Ki67参与了NSCLC的发生发展,p16和Ki67的表达水平与NSCLC的发展及预后有一定的关系。 相似文献
995.
D. Yu. Nazarov A. V. Kucheryavyi K. A. Savvaitova M. A. Gruzdeva K. V. Kuzishchin D. S. Pavlov 《Journal of Ichthyology》2011,51(4):277-290
Phenetic diversity is investigated and the taxonomic status of lampreys (Petromyzontidae) from the Kol basin (Western Kamchatka)
is verified. Typically anadromous lamprey, anadromous lamprey forma praecox, resident lamprey, smolts, and larvae of lamprey
are discovered and described. Their comparative analysis is made by standard morphometric characters. Differences between
the forms by plastic characters depend on size and weight. No significant differences are found by major taxonomic characters
between the forms of anadromous and resident lampreys which would indicate their taxonomic separation. Phenetic types of spawners
are representatives of the population of one complexly structured species represented by life forms realizing different life
history strategies (anadromous and resident), and belong to the species Arctic lamprey Lethenteron camtschaticum (Tilesius, 1811). 相似文献
996.
Yu B Yang M Wong HY Watt RM Song E Zheng BJ Yuen KY Huang JD 《Applied microbiology and biotechnology》2011,91(1):177-188
Live attenuated Salmonella enterica serovar Typhi Ty21a (Ty21a) is an important vaccine strain used in clinical studies for typhoid fever and as a vaccine vector
for the expression of heterologous antigens. To facilitate the use of Ty21a in such studies, it is desirable to develop improved
strategies that enable the stable chromosomal integration and expression of multiple heterologous antigens. The phage λ Red
homologous recombination system has previously been used in various gram-negative bacteria species to mediate the accurate
replacement of regions of chromosomal DNA with PCR-generated ‘targeting cassettes’ that contain flanking regions of shared
homologous DNA sequence. However, the efficiency of λ Red-mediated recombineering in Ty21a is far lower than in Escherichia coli and other Salmonella typhimurium strains. Here, we describe an improved strategy for recombineering-based methods in Ty21a. Our reliable and efficient method
involves the use of linear DNA-targeting cassettes that contain relatively long flanking ‘arms’ of sequence (ca. 1,000 bp)
homologous to the chromosomal target. This enables multiple gene-targeting procedures to be performed on a single Ty21a chromosome
in a straightforward, sequential manner. Using this strategy, we inserted three different influenza antigen expression cassettes
as well as a green fluorescent protein gene reporter into four different loci on the Ty21a chromosome, with high efficiency
and accuracy. Fluorescent microscopy and Western blotting analysis confirmed that strong inducible expression of all four
heterologous genes could be achieved. In summary, we have developed an efficient, robust, and versatile method that may be
used to construct recombinant Ty21a antigen-expressing strains. 相似文献
997.
利用切片方法观察了猞猁Felislynx肝脏的组织结构,应用免疫组织化学方法检测了表皮生长因子(EGF)在肝脏中的表达。结果显示,肝脏外被覆一层结缔组织薄膜,肝小叶不规则且分界不清,肝板、肝血窦及狄氏间隙围绕中央静脉呈放射状排列,肝板由一排肝细胞构成。肝细胞呈圆形或多边形,多为单核,少数具双核,肝细胞间比较松散。肝血窦发达,内可见血细胞。EGF阳性反应主要定位于肝细胞质中,表明EGF可能参与细胞新陈代谢过程的调控。 相似文献
998.
Xi YD Yu HL Ma WW Ding BJ Ding J Yuan LH Feng JF Xiao R 《Journal of bioenergetics and biomembranes》2011,43(4):399-407
The antioxidative properties of genistein (Gen) have been demonstrated by our previous studies and others, but its potential
mechanism was not very clear. Because of the key role of mitochondria in oxidant production, we wondered if mitochondria were
one of Gen’s neuroprotective targets. In the present study we investigated whether Gen has protective effects on mitochondria
damaged by Aβ25-35. PC12 cells were pre-incubated with or without Gen for 2 h followed by the incubation with 20 μM Aβ25-35
for another 24 h before mitochondrial membrane fluidity (MMF), mitochondrial membrane potential (MMP) , and mitochondrial
redox state were measured. The results showed that Gen alleviated the decrease of MMF induced by Aβ25-35, and maintained the
MMP. Additionally, Gen promoted the mitochondrial antioxidative capability through increasing the GSH/GSSG ratio, GPx activity
and MnSOD protein expression in mitochondria. Moreover, Gen reversed the changes of ChAT mRNA and AChE mRNA expression in
cells induced by Aβ25-35. These results suggested that Gen can protect the mitochondrial membrane and maintain redox state
in mitochondria damaged by Aβ25-35. 相似文献
999.
Yu. A. Reunova N. A. Aizdaicher N. K. Khristoforova A. A. Reunov 《Russian Journal of Marine Biology》2007,33(3):166-172
The effects of selenium (0.01, 0.5, 1, 5 and 10 mg/liter) on the growth and ultrastructure of the microalga Dunaliella salina were investigated following its transfer into clean water. Selenium concentrations of 5 and 10 mg/liter were toxic to D. salina, and reinoculation of microalga into clean water did not prevent it from total mortality. When reinoculated from medium with 0.01 mg Se/liter, the cell population density of D. salina was restored in 14 days. The number of ultrastructural alterations in cells was the same as in the control, while the excretory activity of microalga between days 4 and 10 of this experiment was higher. Cell population growth of D. salina transferred from 0.5 and 1 mg Se/liter was lower than in the control. No ultrastructural defects were observed in microalga reinoculated from medium with a selenium concentration of 0.5 mg/liter and the excretion level corresponded to that at 0.01 mg/liter. Various types of ultrastructural damage were found in microalga from medium with 1 mg Se/liter, which was previously reported to be threshold for D. salina; however, the number of cell injuries decreased with increasing time in clean medium. Excretory activity was decreased at the beginning of experiment; but after 7 days, it was restored to the control level. Though there were no ultrastructural alterations in microalgal cells from medium with 0.5 mg Se/liter, we assume that they had molecular defects that could inhibit the cell population growth. The study of microalgae following their reinoculation from medium containing toxicants into clean medium can be a useful method for evaluating algal survival after toxic exposure. 相似文献
1000.
Cho EJ Hwang HJ Kim SW Oh JY Baek YM Choi JW Bae SH Yun JW 《Applied microbiology and biotechnology》2007,75(6):1257-1265
The anti-diabetic activities of the exopolysaccharides (EPS) produced by submerged mycelial culture of two different mushrooms,
Tremella fuciformis and Phellinus baumii, in ob/ob mice were investigated. All the animals were randomly divided into three groups with seven animals in each group: The control
group received 0.9% NaCl solution; the diabetic groups were treated with EPS from T. fuciformis (Tf EPS) and P. baumii (Pb EPS) at the level of 200 mg/kg body weight using an oral zoned daily for 52 days. The plasma glucose levels in the EPS-fed
mice were substantially reduced by about 52% (Tf EPS) and 32% (Pb EPS), respectively, as compared to control mice. The results
of oral glucose tolerance test (OGTT) revealed that both EPS-fed groups significantly increased the glucose disposal after
52 days of EPS treatments. Furthermore, higher food efficiency ratios and reduced blood triglyceride levels were observed
in the EPS-treated groups. Because peroxisome proliferator-activated receptor gamma (PPAR-γ) is indeed a key regulator of
insulin action, we investigated the expression pattern of adipose tissue PPAR-γ messenger RNA (mRNA) and plasma levels of
PPAR-γ. It was revealed that PPAR-γ was significantly activated in response to EPS treatments. The results suggested that
both EPS exhibited considerable hypoglycemic effect and improved insulin sensitivity possibly through regulating PPAR-γ-mediated
lipid metabolism. Our results indicated that two mushroom-derived EPS might be developed as potential oral hypoglycemic agents
or functional foods for the management of non-insulin-dependent diabetes mellitus. 相似文献