An explosive outbreak of respiratory streptococcal infection with a droplet transmission mechanism

The data obtained in the study of an explosive outbreak of acute respiratory diseases, tonsillitis and scarlet fever in one of schools in Moscow have made it possible to exclude the alimentary mechanism of its development and to demonstrate the role of the droplet mechanism of transmission in the appearance of its outbreak. The epidemiological analysis of the outbreak has permitted the formulation of the hypothesis on the conditions of the formation and spread of the epidemic variant of the infective agent; this hypothesis corresponds to the available data in literature on the qualitative changes of the infective agent in the course of the epidemic process. The study has shown that the prophylaxis of the explosive outbreaks of respiratory streptococcal infections must be ensured by the system of epidemiological surveillance with timely intervention into the epidemiological process at its early stages.     

Two loci in the genome of the transposable phage B39 of Pseudomonas aeruginosa affecting the process of integration. I. Study of the properties of phages with the Pde- phenotype and mapping of the rms site

Mutants and recombinants of transposable Pseudomonas aeruginosa bacteriophage B39 with a specific phenotype Pde- (pleiotropic developmental effect) were studied. Pde- phages produce clear minute plaques on lawns of P. aeruginosa PAO1 and fail to grow in cells of PAO1 harbouring Rms 163 (Inc P5) plasmid. Pde+ character is under control of the two loci in phage genome which were designated pdeX and pdeY. In hybrid phages the pdeX and pdeY loci originating from different transposable phages (pdeX from B39 and pdeY from PH132) do not accomplish their function and, as a result, the hybrid phages have the Pde- phenotype. The frequency of integration (f.o.i.) of Pde- phages into bacterial chromosome is lower than f.o.i. for Pde+ phages, as well as the frequency of stable lysogenization of infected bacteria; lytic development of the Pde- phages is also limited. The great difference among the transposable phages in their reaction to the presence of Rms163 plasmid is caused by some differences in the specific rms site in the phage genome. The site is located inside the interval 1.1-3.9 kb of the physical genome map, being closely linked to cI gene of phage B39. The growth of Pde- phages in cells with Rms163 can be restored, due to additional mutations in phage genes affecting lysogenization.     

Stimulation of the lysogenization of Pseudomonas aeruginosa cells by phage transposon B39 induced by plasmid Rms163

The influence of Rms163 plasmid on lysogenization of Pseudomonas aeruginosa cells by B39 phage was studied. Plasmid Rms163 was shown to increase the frequency of lysogenization of PAO1 cells 7-8 times. C-mutants of B39 phage were isolated. According to complementation test, c-mutants were distributed into two groups--cI and cII/III. The product of cI is essential for establishment and maintenance of lysogenic state, cII/cIII product being only necessary for establishment of lysogenization. The mutants with special characteristics were isolated: B39cx1 phage carries a mutation which seems to be located on a regulatory site essential for establishment of lysogenic state. The region of the B39 genome responsible for interaction with Rms163 plasmid was mapped. Possible mechanisms of Rms163 plasmid interference with transposable B39 phage are discussed.     

Proliferative and Differentiation Potential of Individual Clones Derived from Bone Marrow Stromal Precursor Cells

We present the results of a study on the proliferative and differentiation potential of individual clones of stromal fibroblasts growing in monolayer cultures of bone marrow cells. Each precursor cell yielding a large colony in primary culture is capable of up to 34 doublings in vitro. The transplantation of clones or monoclonal strains of stromal fibroblasts into the open system results in the formation of microenvironment consisting of the bone and reticular tissue and is suitable for the differentiation of all three lines of hemopoiesis. Evidence has been obtained that, in a closed system, individual clones are capable of differentiation into the bone, cartilaginous, and reticular tissues. In other words, the adult organism has a common cell precursor for these tissues.     

An Informational Approach to the Analysis of the Low-Frequency Neuronal Impulse Activity in the Rostral Hypothalamus

Statistical analysis of the low-frequency (1.0 sec^-1 and lower) neuronal impulse activity (IA) meets a few fundamental difficulties. Among them, the most significant is the small number of measurements (interspike intervals) recorded within an acceptable analysis epoch. In our study, we examined the possibility of using the normalized (by its maximum value) informational entropy (Hn) for estimation of the significance of changes in the IA generated by low-frequency neurons of the rostral hypothalamus after electrical stimulation of the prefrontal cortex. We compared the efficiencies of using the U-test (Kolmogorov–Mann–Whitney) and Hn estimate for the analysis of the same samples of neuronal responses. The results allow us to conclude that Hn is a significantly more acceptable estimate for detection of stimulation-induced modifications of the IA generated by low-frequency neurons, as compared with the U-test. The direction of shifts in the Hn value makes it possible to estimate the pattern of neuronal response. This value reflects the state of the neuron and correlates with the type of neuronal responses.     

Changes in peroxidation under conditions of 3,4-benzypyrene-induced carcinogenesis

The activities of enzymatic systems generating and destroying peroxides and the lipid peroxide content in neoplastic rat liver and 3,4-benzpyrene-induced sarcoma were studied. The tumour was characterized by high activity of glutathione peroxidase and low activity of catalase. No urate- and glycolate oxidases or ascorbat dependent peroxidation of lipids and lipid peroxides were found in the tumour. In the liver of neoplastic animals the activities of glutathione peroxidase and NADPH-dependent system of microsomal phospholipid peroxidation and the lipd peroxides content were increased, whereas the activities of catalase and urate oxidase were decreased.     

Thermally induced cyclization of L‐isoleucyl‐L‐alanine in solid state: Effect of dipeptide structure on reaction temperature and self‐assembly

Thermal treatment of short‐chain oligopeptides is able to initiate the process of their self‐assembly with the formation of organic nanostructures with unique properties. On the other hand, heating can lead to a chemical reaction with the formation of new substances with specific properties and ability to form structures with different morphology. Therefore, in order to have a desired process, researcher needs to find its temperature range. In the present work, cyclization of _L‐isoleucyl‐_L‐alanine dipeptide in the solid state upon heating was studied. Kinetic parameters of this reaction were estimated within the approaches of the nonisothermal kinetics. The correlation between side chain structure of dipeptides and temperature of their cyclization in the solid state was found for the first time. This correlation may be used to predict the temperature, at which dipeptide self‐assembly changes to chemical reaction. The differences in self‐assembly of linear and cyclic dipeptides were demonstrated using atomic force microscopy. The effect of dipeptide concentration in a source solution and an organic solvent used on self‐assembly of dipeptides was shown. The new information obtained on the thermal properties and self‐assembly of linear and cyclic forms of _L‐isoleucyl‐_L‐alanine may be useful for the design of new nanomaterials based on oligopeptides, as well as for the synthesis of cyclic oligopeptides.     

Relationship of aerobic and anaerobic parameters with 400 m front crawl swimming performance

The aims of the present study were to investigate the relationship of aerobic and anaerobic parameters with 400 m performance, and establish which variable better explains long distance performance in swimming. Twenty-two swimmers (19.1±1.5 years, height 173.9±10.0 cm, body mass 71.2±10.2 kg; 76.6±5.3% of 400 m world record) underwent a lactate minimum test to determine lactate minimum speed (LMS) (i.e., aerobic capacity index). Moreover, the swimmers performed a 400 m maximal effort to determine mean speed (S400m), peak oxygen uptake (V.O2PEAK) and total anaerobic contribution (C_ANA). The C_ANA was assumed as the sum of alactic and lactic contributions. Physiological parameters of 400 m were determined using the backward extrapolation technique (V.O2PEAK and alactic contributions of C_ANA) and blood lactate concentration analysis (lactic anaerobic contributions of C_ANA). The Pearson correlation test and backward multiple regression analysis were used to verify the possible correlations between the physiological indices (predictor factors) and S400m (independent variable) (p < 0.05). Values are presented as mean ± standard deviation. Significant correlations were observed between S400m (1.4±0.1 m·s^-1) and LMS (1.3±0.1 m·s^-1; r = 0.80), V.O2PEAK (4.5±3.9 L·min^-1; r = 0.72) and C_ANA (4.7±1.5 L·O₂; r= 0.44). The best model constructed using multiple regression analysis demonstrated that LMS and V.O2PEAK explained 85% of the 400 m performance variance. When backward multiple regression analysis was performed, C_ANA lost significance. Thus, the results demonstrated that both aerobic parameters (capacity and power) can be used to predict 400 m swimming performance.