Aurin tricarboxylic acid, the anti-AIDS compound, prevents the binding of interferon-alpha to its receptor

Binding of HIV to its receptor, the CD4 molecule of lymphocytes, can be prevented by chemical agents. These agents could be considered as potential anti-AIDS drugs. We have shown that aurin tricarboxylic acid (ATA, 3 microM) specifically blocks the binding of gp120, the HIV coat protein, to the CD4 molecule. We have also found that ATA prevents the binding of interferon-alpha to its receptor in a dose-dependent manner (12-50 microM range). Membrane potential shift, associated with binding of interferon-alpha to its receptor, was also blocked by ATA in a dose-dependent fashion. Our results indicate that potential anti-AIDS drugs should be screened for such undesired side effects.     

Efficiency of Neopsylla abagaitui fleas as plague vectors in Transbaikalia

Experiments have shown that the block of proventriculus develops in 1.1 to 1.5% of individuals of the flea Neopsylla abagaitui infected with plague microbe. These insects transmit the agent during bloodsucking to different plague carriers (Citellus dauricus, C. undulatus, Meriones unguiculatus, Microtus gregalis). The plague microbe is preserved in fleas for 65 days (the observation period).     

Molecular basis for the polymorphic forms of human serum paraoxonase/arylesterase: glutamine or arginine at position 191, for the respective A or B allozymes.

The paraoxonase/arylesterase gene is located close to the cystic fibrosis gene on chromosome 7. Human serum contains two paraoxonase/arylesterase allozymes, A and B, which differ in their substrate specificities and kinetic properties. Purified A, AB, and B esterases were digested with trypsin, and the resultant peptides were compared by high-performance liquid chromatography. The elution profiles were very similar for all three samples, except for (1) one peptide (i.e., peptide A) seen only in the A and AB profiles and (2) another peptide (i.e., peptide B) seen only in the B and AB profiles. Sequencing revealed that peptide A had glutamine at amino acid position 191, whereas peptide B was generated by cleavage on the carboxy side of position 191, presumably because there was a basic (trypsin-specific) amino acid at that position. Working independently, our laboratory and one other laboratory have sequenced the coding region for paraoxonase from human liver cDNA libraries and have identified two polymorphic sites: Arg/Gln at position 191 and Leu/Met at position 54. Using PCR amplification and direct sequencing of nucleotides in both polymorphic regions with genomic DNA, we have estimated the allelic frequencies and have determined their concordance with the serum paraoxonase allozyme phenotypes in 27 unrelated adults and in 16 members of a three-generation pedigree. Among unrelated individuals, the Met/Leu polymorphism at position 54 did not correlate with the serum esterase phenotype. In contrast, the particular amino acid at position 191 correlated perfectly with serum phenotypes: A-type individuals had Gln at position 191, and B-type individuals had Arg at position 191; AB-type serum was found only with the heterozygous (Arg/Gln) combination. Pedigree analysis showed both polymorphisms to be inherited in the expected Mendelian manner and confirmed that only the 191 polymorphism showed concordance with the serum paraoxonase/arylesterase phenotypes.     

Southeast Asian Mitochondrial DNA Analysis Reveals Genetic Continuity of Ancient Mongoloid Migrations

Human mitochondrial DNAs (mtDNAs) from 153 independent samples encompassing seven Asian populations were surveyed for sequence variation using the polymerase chain reaction (PCR), restriction endonuclease analysis and oligonucleotide hybridization. All Asian populations were found to share two ancient AluI/DdeI polymorphisms at nps 10394 and 10397 and to be genetically similar indicating that they share a common ancestry. The greatest mtDNA diversity and the highest frequency of mtDNAs with HpaI/HincII morph 1 were observed in the Vietnamese suggesting a Southern Mongoloid origin of Asians. Remnants of the founding populations of Papua New Guinea (PNG) were found in Malaysia, and a marked frequency cline for the COII/tRNA(Lys) intergenic deletion was observed along coastal Asia. Phylogenetic analysis indicates that both insertion and deletion mutations in the COII/tRNA(Lys) region have occurred more than once.     

流行性出血热地鼠肾细胞灭活疫苗人体试用细胞免疫反应观察

观察了20位志愿者在接种试验性流行性出血热(EHF)地鼠肾细胞(GHKC)双价灭活疫苗后的细胞免疫反应,并以其体液免疫反应作对照观察。用淋巴细胞转化试验测定细胞免疫水平。结果首针疫苗接种后42天和56天,特异性刺激指数(SSI)和非特异性刺激指数(NSI)均较免疫前显著增高(P_(SSI)<0.001;P_(NSI)<0.02),免疫后SSI累计阳转率为100％,NSI累计阳转率为60％,免疫后6个月二者均降低至正常水平。免疫后56天测定抗体,荧光抗体阳转率为100％;微量感染性中和试验表明,针对家鼠型病毒L99株中和抗体阳转率为95％,而针对野鼠型病毒JR株阳转率为65％。     

α-肿瘤坏死因子的肿瘤靶向性改造

α-肿瘤坏死因子(tumor necrosis factor-α,TNF-α)是一种多效性的细胞因子,能高效地杀伤或抑制肿瘤细胞。但是由于其对全身有毒副作用,这使T N F-α的应用受到了限制。提高T N F-α的抗肿瘤活性,降低毒副作用以及开发具有肿瘤靶向性的融合蛋白是将其应用于临床的关键。     

滞育和非滞育棉铃虫前胸腺的形态解剖学比较研究

该文用解剖镜和电子显微镜对滞育和非滞育棉铃虫Helicoverpa armigera前胸腺的形态解剖结构进行了比较研究。结果发现滞育棉铃虫的前胸腺细胞及其细胞间隙相对较小,不易着色,细胞核规则,较小,细胞质中几乎见不到光滑内质网和粗面内质网,线粒体极少,这些观察到的现象充分说明滞育棉铃虫的前胸腺活性较低。     

Monomeric solution structure of the helicase-binding domain of Escherichia coli DnaG primase

DnaG is the primase that lays down RNA primers on single-stranded DNA during bacterial DNA replication. The solution structure of the DnaB-helicase-binding C-terminal domain of Escherichia coli DnaG was determined by NMR spectroscopy at near-neutral pH. The structure is a rare fold that, besides occurring in DnaG C-terminal domains, has been described only for the N-terminal domain of DnaB. The C-terminal helix hairpin present in the DnaG C-terminal domain, however, is either less stable or absent in DnaB, as evidenced by high mobility of the C-terminal 35 residues in a construct comprising residues 1-171. The present structure identifies the previous crystal structure of the E. coli DnaG C-terminal domain as a domain-swapped dimer. It is also significantly different from the NMR structure reported for the corresponding domain of DnaG from the thermophile Bacillus stearothermophilus. NMR experiments showed that the DnaG C-terminal domain does not bind to residues 1-171 of the E. coli DnaB helicase with significant affinity.     

红豆杉生物工程的研究进展

自从紫杉醇(taxol,又称paclitaxel,结构见图1)被批准作为植源性抗癌药应用以来,由于其天然资源的限制,使得近几年来对寻找及扩大紫杉醇药源途径的研究取得了极大的进展。这些途径大致包括:(1)筛选高产量红豆杉(Taxus)栽培品种,(2)化学合成,(3)生物技术,(4)微生物生产。在这些研究领域特别是生物技术研究领域中,由于目前对紫杉醇的生物合成及关键酶研究所取得的进展,已使人们相信通过基因工程手段作为最佳生产紫杉醇药源途径之一,在不久的将来将会变为现实。本文报道的就是有关紫杉醇在生物工程方面的研究进展概况。1　研究简史红豆杉体外培…