SK&F 96365, a novel inhibitor of receptor-mediated calcium entry.

A novel inhibitor of receptor-mediated calcium entry (RMCE) is described. SK&F 96365 (1-(beta-[3-(4-methoxy-phenyl)propoxy]-4-methoxyphenethyl)-1H- imidazole hydrochloride) is structurally distinct from the known 'calcium antagonists' and shows selectivity in blocking RMCE compared with receptor-mediated internal Ca2+ release. Human platelets, neutrophils and endothelial cells were loaded with the fluorescent Ca2(+)-indicator dyes quin2 or fura-2, in order to measure Ca2+ or Mn2+ entry through RMCE as well as Ca2+ release from internal stores. The IC50 (concn. producing 50% inhibition) for inhibition of RMCE by SK&F 96365 in platelets stimulated with ADP or thrombin was 8.5 microM or 11.7 microM respectively; these concentrations of SK&F 96365 did not affect internal Ca2+ release. Similar effects of SK&F 96365 were observed in suspensions of neutrophils and in single endothelial cells. SK&F 96365 also inhibited agonist-stimulated Mn2+ entry in platelets and neutrophils. The effects of SK&F 96365 were independent of cell type and of agonist, as would be expected for a compound that modulates post-receptor events. Voltage-gated Ca2+ entry in fura-2-loaded GH3 (pituitary) cells and rabbit ear-artery smooth-muscle cells held under voltage-clamp was also inhibited by SK&F 96365; however, the ATP-gated Ca2(+)-permeable channel of rabbit ear-artery smooth-muscle cells was unaffected by SK&F 96365. Thus SK&F 96365 (unlike the 'organic Ca2+ antagonists') shows no selectivity between voltage-gated Ca2+ entry and RMCE, although the lack of effect on ATP-gated channels indicates that it discriminates between different types of RMCE. The effects of SK&F 96365 on functional responses of cells thought to be dependent on Ca2+ entry via RMCE were also studied. Under conditions where platelet aggregation is dependent on stimulated Ca2+ entry via RMCE, the response was blocked by SK&F 96365 with an IC50 of 15.9 microM, which is similar to the IC50 of 8-12 microM observed for inhibition of RMCE. Adhesion and chemotaxis of neutrophils were also inhibited by SK&F 96365. SK&F 96365 is a useful tool to distinguish RMCE from internal Ca2+ release, and to probe the role of RMCE in mediating functional responses of cells. However, SK&F 96365 is not as potent (IC50 around 10 microM) or selective (also inhibits voltage-gated Ca2+ entry) as would be desirable, so caution must be exercised when using this compound.     

Construction and packaging of pseudotype retrovirus containing human N—ras cDNA antisense sequence and its biological effects on human hepatoma cells

N-ras is one of the transforming genes in human hepatic cancer cells.It has been found that N-ras was overexpressed at the mRNA and protein level in hepatoma cells.In order to explore the biological roles of N-ras in human hepatic carcinogenesis and the potential application in control of cancer cell growth,a preudotype retrovirus containing antisense sequence of human N-ras was constructed and packaged.A recombinant retrovirus vector containing antisense or sense sequences of N-ras cDNA was constructed by pZIP-NeoSV(X)1.The pseudotype virus was packaged ang rescued by transfection and infection in PA317 and ψ 2 helper cells.It has been demonstrated that the pseudotype retrovirus containing antisense N-ras sequence did inhibit the growth of human PLC/PRF/5 hepatoma cells accompanied with inhibition of p21 expression,while the retrovirus containing sense sequence had none.The pseudotype virus had no effect on human diploid fibroblasts.     

吉林省寄螨亚科三新种(啤螨目:寄螨科)

本文记述寄螨亚科(Parasitinae)三新种。模式标本保存于吉林省地方病第一防治研究所。文内测量单位为微米,括号内为测量平均值。     

腐霉属分类性状评价及其中国的种

本文对腐霉属Pythium Pringsheim的研究历史作了简单的回顾,对该属的分类性状和系统进行了论述和评价,最后对中国已发现的55种腐霉,以检索表的方式进行了分类、检索。     

Deep-level diagnostic value of the rDNA-ITS region

The similarity of certain reported angiosperm rDNA internal transcribed spacer (ITS) region sequences to those of green algae prompted our analysis of the deep-level phylogenetic signal in the highly conserved but short 5.8S and hypervariable ITS2 sequences. We found that 5.8S sequences yield phylogenetic trees similar to but less well supported than those generated by a ca. 10-fold longer alignment from rDNA-18S sequences, as well as independent evidence. We attribute this result to our finding that, compared to 18S, the 5.8S has a higher proportion of sites subject to vary and greater among-site substitution rate homogeneity. We also determined that our phylogenetic results are not likely affected by intramolecular compensatory mutation to maintain RNA secondary structure nor by evident systematic biases in base composition. Despite historical homology, there appears to be no ITS2 primary sequence similarity shared sufficient similarity to cluster correctly on the basis of alignability. Our results indicate that groups, however, share sufficient similarity to cluster correctly on the basis of alignability. Our results indicate that ITS region sequences can diagnose organismal origins and phylogenetic relationships at many phylogenetic levels and provide a useful paradigm for molecular evolutionary study.      

Influences on the antimicrobial activity of surface-adsorbed nisin

The efficacy of the antimicrobial peptide nisin was examined after adsorption to silica surfaces. Three protocols were used to evaluate nisin's activity against adhered cells ofListeria monocytogenes: bioassay usingPediococcus pentosaceous FBB 61-2 as the sensitive indicator strain; visualization and enumeration of cells by microscopic image analysis; and viability of adhered cells as determined by lodonitrotetrazolium violet uptake and crystallization. The activity of adsorbed nisin was highly dependent upon conditions of adsorption. The highest antimicrobial activity of adsorbed nisin occurred with high concentrations of nisin (1.0 mg ml^–1) and brief contact times (1 h) on surfaces of low hydrophobicity. Sequential adsorption of a second protein (-lactoglobulin or bovine serum albumin) onto surfaces consistently resulted in decreased nisin activity. These data provide direction for the development of applications to limit microbial attachment on food contact surfaces through the use of adsorbed antimicrobial peptides.     

山西雏蝗属二新种：直翅目：网翅蝗科

本文记述山西省雁北地区雏蝗属Ｃｈｏｒｔｈｉｐｕｓ Ｆｉｅｂｅｒ１８５２二新种,即郑氏雏蝗Ｃｈｏｒｔｈｉｐｐｕｓ ｚｈｅｎｇｉ,ｓｐ．ｎｏｖ．和宽带雏蝗Ｃｈｏｒｔｈｉｐｐｕｓ ａｍｐｌｉｌｉｎｅａｔｕｓ,ｓｐ．ｎｏｖ。模式标本保存在山西省农牧厅植保植检总结。     

简便、快速提取高质量的RNA分子

MethodsforHandy,RapidIsolationofHighQualityRNAbyGuanadiumThioeyauateDuJianYuanYanhuaMaShenglinDongZhiwei(BeijingInstituteforCancerResearchBeijing100034)硫氰胍是一种有效的蛋白变性剂。早在1979年,Chirgwin等就利用氯化铯／硫氰胍超离心技术成功地从RNA酶富集的胰脏组织中提取出未降解的RNA分子[2],从而使它成为抑制RNA酶的首选药物并得到广泛使用,但受到超速离心设备的限制。1983年,Cathala报道了氯化锂／硫氰胍RNA提取法[1]。该方法操作简便,获得的RNA质量很高,但所需时间较长。为了能在短时间内更快…     

Crystal structure of cholera toxin B-pentamer bound to receptor GM1 pentasaccharide.

Cholera toxin (CT) is an AB5 hexameric protein responsible for the symptoms produced by Vibrio cholerae infection. In the first step of cell intoxication, the B-pentamer of the toxin binds specifically to the branched pentasaccharide moiety of ganglioside GM1 on the surface of target human intestinal epithelial cells. We present here the crystal structure of the cholera toxin B-pentamer complexed with the GM1 pentasaccharide. Each receptor binding site on the toxin is found to lie primarily within a single B-subunit, with a single solvent-mediated hydrogen bond from residue Gly 33 of an adjacent subunit. The large majority of interactions between the receptor and the toxin involve the 2 terminal sugars of GM1, galactose and sialic acid, with a smaller contribution from the N-acetyl galactosamine residue. The binding of GM1 to cholera toxin thus resembles a 2-fingered grip: the Gal(beta 1-3)GalNAc moiety representing the "forefinger" and the sialic acid representing the "thumb." The residues forming the binding site are conserved between cholera toxin and the homologous heat-labile enterotoxin from Escherichia coli, with the sole exception of His 13. Some reported differences in the binding affinity of the 2 toxins for gangliosides other than GM1 may be rationalized by sequence differences at this residue. The CTB5:GM1 pentasaccharide complex described here provides a detailed view of a protein:ganglioside specific binding interaction, and as such is of interest not only for understanding cholera pathogenesis and for the design of drugs and development of vaccines but also for modeling other protein:ganglioside interactions such as those involved in GM1-mediated signal transduction.     

Comparative analysis of multiple protein-sequence alignment methods [published erratum appears in Mol Biol Evol 1994 Sep;11(5):811]

We have analyzed a total of 12 different global and local multiple protein-sequence alignment methods. The purpose of this study is to evaluate each method's ability to correctly identify the ordered series of motifs found among all members of a given protein family. Four phylogenetically distributed sets of sequences from the hemoglobin, kinase, aspartic acid protease, and ribonuclease H protein families were used to test the methods. The performance of all 12 methods was affected by (1) the number of sequences in the test sets, (2) the degree of similarity among the sequences, and (3) the number of indels required to produce a multiple alignment. Global methods generally performed better than local methods in the detection of motif patterns.