Plasmid expression vectors with elements of the E. coli alkaline phosphatase gene

A family of plasmid expression vectors, containing fragments of the E. coli alkaline phosphatase gene (phoA), has been constructed for the lambda PR promoter-directed thermoinducible superproduction of fusions of heterologous polypeptides to the N- or C-terminus of E. coli alkaline phosphatase and its leader peptide. Effective expression and export to periplasm of resulting fusion proteins, which may retain enzymatic activity of the phosphatase, has been shown.     

人眼微光下夜近视机制的研究

本文利用激光散斑屈光测试系统详细探讨了夜近视(night myopia)的产生机制。夜近视在环境亮度降低到产生暗视觉时出现,并随亮度继续降低而增大,平均值为1.35D。实验证明眼睛球差和色差不是造成夜近视的主要因素。夜近视数值在暗适应过程中呈增大的趋势。在暗视觉时,由于视野中缺少适宜的刺激,眼睛处于暗焦(dark focus)休止状态,这是造成夜近视的主要原因。     

Use of the immunofluorescence reaction for evaluating the immunological transformation in those inoculated with a chemical typhus vaccine

The results of the serological examination of persons immunized with chemical typhus vaccine (CTV) are presented. The examination was carried out by means of the complement fixation test (CFT), the passive hemagglutination test (PHAT), the toxin neutralization test (TNT) and the immunofluorescence test (IFT). The acetone-fixed live culture of Rickettsia prowazekii, strain Breinl, served as antigen in IFT. If persons immunized with CTV showed positive titers in CFT, TNT and PHAT, the results of IFT were highly correlated with the CFT titers. In 6-12 months after immunization with CTV the titers of CFT, TNT and PHAT became negative, while the IFT titers remained positive for several subsequent years.     

P-(alkyl)-nucleoside 5'-hydrogenphosphonates as depot forms of antiviral nucleotide analogues

P-(Alkyl)esters of AZT 5'-hydrogenphosphonate were synthesized and their stabilities in the phosphate buffer and human serum were evaluated. The esters bearing residues of primary and secondary alcohols were degraded to give AZT, whereas those containing tertiary alkyl groups yielded AZT 5'-hydrogenphosphonate. The corresponding derivatives of d2A and d4T showed the same properties.     

ANTIPYRETIC ACTION OF DEXAMETHASONE ON EGTAZIC ACIDINDUCED FEVER IN RABBITS

本文用脑室灌注和Ｆｕｒａ２测定细胞内游离钙技术观察了地塞米松（ｄｅｘａｍｅｔｈａｓｏｎｅ,ＤＥＸ）对家兔乙二醇双（２氨基乙醚）四乙酸性发热效应和下丘脑细胞内游离钙浓度（［Ｃａ２＋］ｉ）的影响,借此深入探讨地塞米松解热作用的中枢机制。结果发现：脑室灌注乙二醇双（２氨基乙醚）四乙酸（０６ｎｍｏｌ）引起家兔结肠温度明显升高,静脉注射地塞米松（５ｍｇ／ｋｇ）显著抑制家兔乙二醇双（２氨基乙醚）四乙酸性发热,地塞米松（６０～１２０μｍｏｌ／Ｌ）并不影响下丘脑细胞内［Ｃａ２＋］ｉ,而事先脑室灌注抑制基因转录的放线菌素Ｄ（３ｎｍｏｌ）则完全取消了地塞米松对乙二醇双（２氨基乙醚）四乙酸性发热的解热作用。这些结果提示：地塞米松显著抑制家兔乙二醇双（２氨基乙醚）四乙酸性发热,其机制与地塞米松激活脑内某些基因的表达有关,而与下丘脑神经细胞跨膜钙离子流无关。     

Biochemical and genetic characterization of three hamster cell mutants resistant to diphtheria toxin

We describe here three different hamster cell mutants which are resistant to diphtheria toxin and which provide models for investigating some of the functions required by the toxin inactivates elongation factor 2 (EF-2). Cell-free extracts from mutants Dtx(r)-3 was codominant. The evidence suggests that the codominant phenotype is the result of a mutation in a gene coding for EF-2. The recessive phenotype might arise by alteration of an enzyme which modifies the structure of EF-2 so that it becomes a substrate for reaction with the toxin. Another mutant, Dtx(r)-2, contained EF-2 that was sensitive to the toxin and this phenotype was recessive. Pseudomonas aeruginosa exotoxin is known to inactivate EF-2 as does diphtheria toxin and we tested the mutants for cross-resistance to pseudomonas exotoxin. Dtx(r)-1 and Dtx(r)-3 were cross-resistant while Dtx(r)-2 was not. It is known that diphtheria toxin does not penetrate to the cytoplasm of mouse cells and that these cell have a naturally occurring phenotype of diphtheria toxin resistance. We fused each of the mutants with mouse 3T3 cells and measured the resistance. We fused each of the mutants with mouse 3T3 cells and measured the resistance of the hybrid cells to diphtheria toxin. Intraspecies hybrids containing the genome of mutants Dtx(r)-1 and Dtx(r)-3 had some resistance while those formed with Dtx(r)-2 were as sensitive as hybrids derived from fusions between wild-type hamster cells and mouse 3T3 cells.     

AZT 5'-Cholinephosphate as an anti-HIV agent: the study of biochemical properties and metabolic transformations using its 32P-labelled counterpart

Biochemical and metabolic transformations of 3'-azido-3'-deoxythymidine 5'-choline phosphate (1) were studied using its 32P-labelled counterpart for the evaluation of possible reasons for its enhanced anti-HIV activity. An effective synthesis of 32P-labelled 1 with a specific activity >1,000 Ci/mmol was developed by esterification of 32P-phosphoric acid with choline in the presence of BrCN followed by the coupling of the resulting choline phosphate with 3'-azido-3'-deoxythymidine (AZT). Chemical and enzymatic stabilities of 1 as well as the dynamics of penetration through HL-60 cell membranes were studied at the concentrations comparable to its antiviral concentrations. The products of intracellular transformations of the studied nucleotide were identified.