Selection and physiological study of culture of Bacillus circulans-- producer of butirosin]

For isolating a highly active variant of the butirosin-producing culture, a strain forming trace amounts of the antibiotic substance was used. Exposure to nitrosomethylbiuret and nitrosoguanidine and the use of selective media containing streptomycin and butirosin resulted in a 30-fold increase in the strain productivity. Thin layer chromatography of the produced antibiotic substance in the solvent system developed by the authors, mass spectrometry and assay of the antimicrobial spectrum in regard to ++gram-positive and ++gram-negative bacteria by using the known aminoglycosidine-inactivating enzymes revealed that the substance was identical to butirosin. Along with the major product, the fermentation broth contained up to 5 per cent of ribostamycin.     

Prevention of infectious complications in patients with acute bone marrow depression]

Clinical efficacy of intravenous gentamicin in combination with oral use of gentamicin, ristomycin and nystatin was studied in 1977. In 1980-1984 two antiinfectious regimens were tested: intravenous administration of gentamicin in combination with total decontamination (oral use of gentamicin and nystatin) and selective decontamination (biseptol with nystatin of amphoglucamine). It was shown that the incidence of severe infections in the patients under the observation dropped against the controls. The incidence and spectrum of infectious complications in cases with acute myelodepressions were proved to depend on the intestinal autoflora inhibition.     

Effect of inhibitors of DNA synthesis on the sensitivity of mammalian cells to radiation with different levels of linear energy transfer

Radiosensitivity of Chinese hamster cells increased by 1.71 times in the presence of arabinoside cytosine and hydroxyurea after gamma-irradiation, and no sensitization occurred after irradiation with carbon ions of 6.6 MeV/nuclon (LET, 227 keV/micron). Under a standard set of conditions, the RBE coefficient of carbon ions decreased from 3.09 to 1.78 in the presence of DNA synthesis inhibitors. The possible mechanism of this phenomenon is discussed.     

A possibility to predict the severity of individual damage following the exposure to supralethal radiation dosage. Prediction by early radiation response

The experiments on dogs and monkeys have shown that the severity of radiation sickness following the exposure to supralethal radiation doses can be predicted by early response of an individual. For such prediction, the most informative criteria include general severity of clinical manifestations during primary radiation response and evaluated within a few post-damage hours, the degree of tension in cardiac rhythm control, the cortisol level, the endocrine status index.     

Variants in the interleukin-1 alpha and beta genes,and the risk for periodontal disease in dogs

Elevated levels of interleukin-1 (IL-1) have been shown to amplify the inflammatory response against periodontopathogenic bacteria. In humans, polymorphisms in the IL1A and IL1B genes are the most well-studied genetic polymorphisms associated with periodontal disease (PD). In contrast to human, there is a lack of knowledge on the genetic basis of canine PD. A case–control study was conducted in which a molecular analysis of dog IL1A and IL1B genes was performed. Of the eight genetic variants identified, seven in IL1A gene and one in IL1B gene, IL1A/1_g.388A >C and IL1A/1_g.521T >A showed statistically significant differences between groups (adjusted OR (95% CI): 0.15 (0.03–0.76), P= 0.022; 5.76 (1.03–32.1), P= 0.046, respectively). It suggests that in the studied population the IL1A/1_g.388C allele is associated with a decreased PD risk, whereas the IL1A/1_g.521A allele can confer an increased risk. Additionally, the IL1A/2_g.515G >T variation resulted in a change of amino acid, i.e. glycine to valine. In silico analysis suggests that this change can alter protein structure and function, predicting it to be deleterious or damaging. This work suggests that IL1 genetic variants may be important in PD susceptibility in canines.     

Estimation of the influence of physical and biological factors on the development of the hematopoietic type of radiation sickness in dogs and two types of monkeys

In this investigation, the analysis of radiobiological experiments on 532 dogs and two types of monkeys (101 animals), irradiated totally in the 1.0 to 6.0 Gy dose range at different irradiation facilities, has been carried out. LD50 values at X-ray and gamma-neutron exposure were close to each other (2.35 and 2.83 Gy, respectively) while at gamma-radiation exposure LD(50/45) increased to 3.09 Gy. Comparison of LD(50/45) values for different kinds of animals allowed us to draw a conclusion of approximately equal radiosensitivities of dogs and Macaca fascicularis monkeys (LD(50/30-45) - 3.09 Gy and 3.17 Gy, respectively); Macaca rhesus monkeys revealed higher radioresistance (LD(50/30-45) - 5.03Gy). Analysis of the influence of several biological factors has not displayed any significant differences in the values of LD(50/45) and average lifespan of male and female dogs. Higher radiosensitivity of dogs with body weight less than 12 kg and lower radiosensitivity of dogs in summer time compared to other seasons have been shown. Dogs at the age of 2 to 3 years appeared to be more radioresistant than animals of the other age.     

The genome instability in the descendants of the Chinese hamster of the cells, irradiated by the low dose and by various intensities of gamma-radiation

The V-79 Chinese hamster cells were irradiated by gamma-rays in dose of 0.5 Gy at powers of doses 0.48 Gy/min (an acute irradiation) and 0.0485 MGy/min (a prolonged irradiation). The acute and prolonged irradiation in a dose of 0.5 Gy enlarges frequency of the appearance of micronucleus (MN). Subsequent cultivation of the irradiated cells during 20 generations enlarges frequency of MN, and for prolonged an irradiation the boosted frequency of MN, is saved during 40-60 generations. After an acute irradiation the number of MN starts to reduce after 20 doublings.     

Cytogenetic effects of low dose radiation with different LET in human peripheral blood lymphocytes and possible mechanisms of their realization

The induction of chromosome damage by the exposure to low doses of gamma-(60)Co and accelerated carbon ions 12C in peripheral blood lymphocytes of different donors was investigated. The complex nonlinear dose-effect dependence at the range from 1 to 50-70 cGy was observed. At the doses of 1-5 cGy the cells show the highest radiosensitivity (hypersensitivity), mainly due to the chromatid-type aberration, which is typical to those spontaneously generated in the cell and believed not to be induced by the irradiation of unstimulated lymphocytes according to the classical theory of aberration formation. With the increasing dose the frequency of the aberrations decreases significantly, in some cases up to the control level. At the doses over 50-70 cGy the dose-effect curve becomes linear. The possible role of the oxidative stress, caused by radiation-induced increase in mitochondrial reactive oxigen species (ROS) release in the phenomenon of hypersensitivity (HS) at low doses is discussed as well as cytoprotective mechanisms causing the increased radioresistance at higher doses.