Effect of,hexylresorcinol, a chemical analogue of bacterial anabiosis autoinducers on the stability of membrane structures

The effect of hexylresorcinol (HR), a chemical analogue of microbial anabiosis autoinducers of the alkylhydroxybenzene (AHB) group, on the stability of biological membranes and monolamellar liposomes formed of egg phosphatidylcholine (ePC) was studied. According to spectrophotometry and electron microscopy studies of HR-loaded liposomes in the presence of a surfactant Tween 20, the critical ratio between HR and ePC for liposome preservation was found to be close to equimolar. The trends in HR influence on membrane structural organization and stability of liposomes were also confirmed in experiments on intact bacterial cells explaining non-species-specific effect of AHBs. The demonstrated high efficiency of AHB biocides may be used in material and equipment protection against biocorrosion.     

Joint culturing of Streptococcus lactis, strain MGU with Proteus vulgaris and Bacillus mesentericus

Nisin synthesis by Streptococcus lactis, strain MGU, grown as a combined culture together with Proteus vulgaris and Bacillus mesentericus under stationary conditions or with stirring does not depend on the quantity of inoculated associated cells. Nisin synthesis in the combined culture drops down by 10-20% at the initial pH 7.5 of the growth medium which is unfavourable for S. lactis producing nisin. The level of nisin biosynthesis does not rise when the pH of the medium is adjusted (either naturally or artificially) to 6.6-6.8 in the presence of glucose and yeast autolysate. S. lactis inhibits the growth of B. mesentericus when grown together with it whereas P. vulgaris inhibits the growth of S. lactis in their combined culture.     

Basic patterns in the epidemic process of measles under conditions of massive immunization]

Observations over the measles epidemic process in Leningrad showed that the sporadic morbidity level reached in 1974--4.1 per 100 000 residents; however periodic elevation and decline of morbidity and tis seasonal variations persisted. A rise of morbidity in 1972--1973, and by preliminary data--in 1975, occurred on account of the older age groups. There was revealed no dependence of the disease incidence among the persons vaccinated on the time lapse after their vaccination. Individual batches of live measles vaccine issued in 1963--1969 were not up to the standard, this serving as one of the cases of the occurence of group incidence of the infection in some foci.     

The analysis of cellular elements in coelomic fluid during early regeneration of of the starfish Asterias rubens L

Three main cell types were found in the coelomic fluid (CF) of intact starfishes: agranulocytes (55-80%) varying in size and form (spherical and ovoid) and with occasional pseudopodia, granulocytes (15-45%), and small cells (up to 2 %) with a high nuclear-cytoplasmic ratio. The starfish response to injury depends on the degree of coelomic fluid loss. After a slight wounding, when only insignificant portion of CF is lost, the cellular composition of circulating fluid changed only slightly. Unlike, a significant injury resulted in rising the share of small cells, regarded presumably as young cells. Besides, after injury the functional characteristics of SF also changed: the proportion of cells with decondensed chromatin and stained nucleoli increased, and coelomocytes acquired ability to form nets at adhesion. Moreover, some new cell types can be found (fusiform cells), with granulocyte proportion in nets increasing. We suppose that after slight wounding circulating coelomocytes may restore from the existing store of differentiated cells beyond the circulation, whereas after significant injury young undifferentiated coelomocytes are involved in the process of restoration.     

主动脉夹层分离的研究现状

主动脉夹层分离是一种临床上不常见但具有潜在灾难性、急危重的疾病。提高临床医师对该病的认识与了解,将有助于对其采取预防措施,提高救治水平。本文对该病近几年的研究进展作一综述。     

Stimulation of the rat's sciatic nerve regeneration by local treatment with Xymedon

1. The possibility of a neuro-protective effect of Xymedon as a pharmacological stimulator of nerve regeneration has been studied through Schwann cells (SCs) located in the potential area of regenerating nerve fibers' growth. 2. Xymedon was injected into the silicone chamber connecting the central and peripheral stumps of the rat's sciatic nerve. Carboxymethyl cellulose was used as a depositioned medium. 3. A 0.95% concentration of Xymedon increased the sciatic nerve functional index (SFI) values on the 14th, 21st and 28th day after the operation. By day 30, the total number of survival neurons in the L5 dorsal root ganglion (DRG) on the ipsilateral side increased with the following changes in Xymedon concentration: [see text] The number of surviving sensory neurons in the group with 0.95% Xymedon increased by 36% (p < 0.05) compared with animals with depositioned medium but Xymedon free. 4. It is suggested that the positive effects of Xymedon on neural regeneration and recovery of motor function support the potential use of Xymedon for the treatment of peripheral nerve injuries.     

Ultrastructure of Resting Cells of Some Non-Spore-Forming Bacteria

Using electron microscopy (ultrathin sections and freeze-fractures), we investigated the ultrastructure of the resting cells formed in cultures of Micrococcus luteus, Arthrobacter globiformis, and Pseudomonas aurantiaca under conditions of prolonged incubation (up to 9 months). These resting cells included cystlike forms that were characterized by a complex cell structure and the following ultrastructural properties: (i) a thickened or multiprofiled cell wall (CW), typically made up of a layer of the preexisting CW and one to three de novo synthesized murein layers; (ii) a thick, structurally differentiated capsule; (iii) the presence of large intramembrane particles (d = 180–270 Å), occurring both on the PF and EF faces of the membrane fractures of M. luteus and A. globiformis; (iv) a peculiar structure of the cytoplasm, which was either fine-grained or lumpy (coarse-grained) in different parts of the cell population; and (v) a condensed nucleoid. Intense formation of cystlike cells occurred in aged (2- to 9-month-old) bacterial cultures grown on diluted complex media or on nitrogen-, carbon-, and phosphorus-limited synthetic media, as well as in cell suspensions incubated in media with sodium silicate. The general morphological properties, ultrastructural organization, and physiological features of cystlike cells formed during the developmental cycle suggest that constitutive dormancy is characteristic of non-spore-forming bacteria.     

安徽省粮仓粉螨群落组成及多样性研究

选取禾谷类、油料类和副产品3类粮仓储藏物采样点各150个,每个采样点各采集样本2份,每份10g,过筛后留取尘渣,进行粉螨的采集、分类、鉴定、计数以及数据分析.共检获粉螨28种,隶属于6科17属.多样性分析结果表明3类储藏物的粉螨物种数为16～21,平均孳生密度为20.61±4.78～54.13±4.27,物种丰富度指数(Margalef指数)为1.979～2.535,多样性指数(Shannon-Wiener指数)为2.160～2.431,均匀度指数(Pielou指数)为0.763～0.816,优势度指数(Simpson指数)为0.118～O.151,相似性指数(Jaccard指数)为0.321～O.65.其粉螨的孳生密度、多样性及相似性差异较大.     

炭疽疫苗免疫小鼠外周血TH2，TH1和浆细胞免疫应答动态观察

为了深入了解炭疽两种疫苗——A16R芽孢苗与炭疽无菌培养滤液佐剂吸附苗（anthrax vaccine adsorbed,AVA苗）诱导小鼠免疫应答类型的差异,筛选疫苗免疫评价有效的免疫学参数,分别从抗体及细胞应答水平上对炭疽两种疫苗免疫Balb／C小鼠后免疫应答产生过程进行了动态观察．抗体检测结果分析显示,A16R芽孢苗免疫小鼠血清中可同时检测到抗芽孢抗体与抗AVA抗体,AVA免疫可诱导小鼠产生高效价的抗AVA抗体;两种疫苗免疫小鼠血清IgG抗体亚型均以kG1和IgG2b为主,A16R免疫组IgG2a明显高于AvA免疫组．细胞应答结果分析显示,两种疫苗免疫外周血中均可检测到抗原特异性的TH2,TH1和浆细胞应答．TH2应答于免疫后5天即可在外周血中检测到,至观察末期仍可维持在较高水平;TH1应答,A16R免疫组出现早于AVA免疫组,免疫后5天即可检测到,AVA免疫组于二次免疫的7天才出现,观察末期两组均可检测到低水平的TH1应答;两种疫苗免疫小鼠外周血中均可检测到抗原特异性的浆细胞,A16R免疫组出现早,维持时间长,至观察末期仍呈现上升趋势,AVA免疫组,浆细胞出现较晚,维持时间较短,观察末期仅检测到低水平的浆细胞．上述结果表明,多抗原刺激物的A16R芽孢苗较AVA能更有效的诱导细胞免疫应答;炭疽疫苗免疫后小鼠外周血中TH2,TH1和浆细胞细胞应答,可以同抗体一起,作为疫苗有效性的免疫评价指标．