Epidemiological problems of ozena and the means for controlling this infection

Clinical, bacteriological, serological and epidemiological studies of ozena morbidity among the population of Minsk were carried out in 1970-1980. On January 1, 1981, the ozena morbidity rate among the inhabitants of Minsk was 26.72%. Ozena was found to affect mainly children and women. A wide spread of the family foci of this disease (31.68%) was revealed. The results of this study indicate that the source of K. ozaenae is a sick person who begins to excrete the bacteria in the prodromal period of the disease and may continue to excrete them for many years. The transfer of K. ozaenae occurs probably by droplet or contact infection. The droplet infection is less active in the absence of symptoms (coughing, sneezing) facilitating excretion of the infective agent into the air and in cases of the low susceptibility of persons to ozena. The main measures for controlling ozena are the timely detection and sanitation of the sources of ozena, as well as the current disinfection of the infection foci in apartments.     

Relation between the changes in the structure and synthesis of DNA in the cells of mouse leukemia L1210 induced by 1-methyl-1-nitrosourea and 1,3-bis(2-chloroethyl)-1-nitrosourea

The damage of DNA structure and synthesis in murine leukemia L1210 cells upon single administration in therapeutic doses of antitumour agents of N-nitrosourea type, such as 1-methyl-1-nitrosourea (MNU) and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) was studied. MNU and BCNU were characterized by stronger inhibitory effects on de novo DNA synthesis compared to additional pathway of DNA synthesis in leukemia L1210 cells in vivo. Centrifugation in alkaline sucrose density gradients of L1210 cell lysates has revealed persistent single-strand breaks and alkaline-labile sites in newly replicated DNA. Parental DNA structure was more stable to damaging drug effects than that of newly replicated DNA. The results are consistent with our previous data on the differences in the mechanisms of MNU and BCNU action and the absence of complete cross resistance between the drugs.     

Viability and proliferative activity of a Chinese hamster cell culture exposed to nitrosoureas in exponential and stationary growth phases

The lethal effect of antitumor nitrosourea chloroethyl derivatives on proliferating (exponential phase of growth) and non-proliferating (stationary phase of growth) cells is observed at a concentration 5-fold less than that of methyl derivatives revealed by the colony-formation technique. 1,3-bis(2-chlororoethyl)-1-nitrosourea is equally effective towards proliferating and non-proliferating cells, but chlorozotocin exerts a primary cytotoxic effect on proliferating cells. 1-methyl-1-nitrosourea at low concentration causes death more readily of proliferating cells than non-proliferating ones. However, studies on proliferative activity during the first hours after treatment with 1-methyl-1-nitrosourea revealed drug sensitivity in cells being at the early stationary phase of growth.     

A study of the effects of flocalin on respiration and potassium transport of rat-heart and liver mitochondria

The effects of the drug flocalin, which possesses cardioprotective properties, on the respiration rates of rat-heart and liver mitochondria in different functional states, the efficiency of oxidative phosphorylation, as well as the transport of potassium ions in these organelles, were studied. It was found that flocalin at concentrations of 7–30 μm stimulated respiration of rat-heart and liver mitochondria in V ₂ and V ₄ states in the presence of succinic add as a respiration substrate in a potassium-containing medium. In the absence of potassium ions in the incubation medium, flocalin had no effect on mitochondrial respiration in these states. Studying the functioning of the potassium transport system revealed that flocalin at these concentrations dose-dependently activated the ATP-dependent transport of potassium ions in rat-heart and liver mitochondria. The data we obtained indicate that the cardioprotective effect of flocalin can be associated with activation of the ATP-dependent potassium channel of the inner mitochondrial membrane.     

Distribution and parameters of genetic polymorphism in northern red-backed vole (<Emphasis Type="Italic">Clethrionomys rutilus</Emphasis>) and bank vole (<Emphasis Type="Italic">Clethrionomys glareolus</Emphasis>) in West Siberia

This article presents data on the genetic variability of the northern red-backed vole and the bank vole that live sympatrically in West Siberia. The two species of voles have comparable, relatively high indices of genetic variability of inter simple sequences repeats DNA. The proportion of polymorphic DNA markers is 95–98%, and the Nei’s genetic diversity index is 0.33–0.35. A total of 47–58% of allozyme loci in the voles are polymorphic, and the average heterozygosity per locus is 0.058 in the northern red-backed vole and 0.054 in the bank vole. Interpopulation differentiation is less pronounced in the red-backed vole (F _ST 0.293) compared to the bank vole (F _ST 0.475). Individuals of the hybrid line of the bank vole with the mitochondrial haplotype of the red-backed vole have been found by PCR typing of cytochrome b gene fragment of mtDNA. The distribution boundary of the hybrid line of bank voles goes farther to the northeast than was shown in earlier works. The proportion of hybrid specimens range from 2 to 34%. The indices of genetic variability in the hybrid line of the bank vole are lower than those of the parental species.     

Peptides analogous to tethered ligands liberated by activated protein C exert neuroprotective effects in glutamate-induced excitotoxicity

Haemostatic proteinases may appear in brain tissue after injury and under inflammation as a result of the blood-brain barrier disruption. Serine proteinases regulate cell functions through G-protein-coupled transmembrane protease-activated receptors (PARs). Proteinases cleave only one peptide bond of receptor exodomain, which results in the formation of a new N-terminus (“tethered ligand”) that can specifically interact with the second extracellular loop of the receptor and activate it. Two types of receptors (EPCR and PAR1) are necessary for the cytoprotective effect of activated protein C (APC) on endothelial cells and neurons. APC activates PAR-1 and controls gene expression of proinflammatory and proapoptotic factors. APC exerts a protective effect in stressed neurons and hypoxic brain endothelium, modulates the activity of endothelial cell genes involved in apoptosis, and stabilizes the endothelial barrier. We suppose that the peptides analogous to the PAR1 tethered ligand released by APC may have a neuroprotective effect similar to that of APC. We have simulated ischemic brain damage using a model of glutamate excitotoxicity on the primary culture of neonatal rat hippocampal neurons. It was shown that NPNDKYEPF-amide (peptide 9) and NPNDKYEPFWE (peptide 11) more effectively reduced the level of apoptosis during neuronal excitotoxicity in comparison with APC, while the influence of these peptides on the number of living and necrotic cells was analogous to that of APC. The findings suggest that the protective effect of the peptides analogous to the PAR1 tethered ligand is comparable to the protective effect of APC under glutamate excitotoxicity. Investigation of the mechanisms of PAR1 agonist peptides action and development of their shortened versions with high neuroprotective activity may be a relevant approach to the search of novel neuroprotective drugs for treating neurodegenerative diseases and strokes.     

The EPR spectra of the ribonucleotide reductase in the tumorous tissues and organs of tumor-bearing animals

Ribonucleotide reductase activity (RRA) has been studied in various tumors and spleens of tumor-bearing animals using EPR technique and biochemical methods. The effect of a number of biologically active compounds on RRA has also been studied. RRA in tumor and spleen increases during tumor growth. Inhibitory effect of irradiation, hydroxyurea, nitrosomethylurea and activatory effect of 5-nitrofurans and nitroimidazole derivatives on RRA has been observed. Regulatory factors of RRA and DNA synthesis in vivo have been discussed.