Quantitative assessments of synergism

The basic approaches to the assessment of the biological effects of combinations of different agents are briefly discussed. The situations of additivity, synergism and antagonism are defined with hetero- and isoaddition being taken into consideration. The practical application of the methods is illustrated by the analysis of the experimental data on the staphylococcus survival after the combined effect of gamma-irradiation and hydrogen peroxide or incubation at elevated temperature.     

Dipeptidyl aminopeptidase-IV in lymphocytes of patients with lymphoproliferative diseases

DAP-IV activity (Gly-Pro-MCA hydrolysis, pH 7.8) was found in lysates of peripheral blood lymphocytes of patients with T- and B-cell forms of malignant lymphoproliferative diseases. The highest DAP-IV activity was seen in the cells of patients with a rare variant of T-cell lymphocytic leukemia (T-CLL); these cells expressed simultaneously the antigens of T helpers and T suppressors (Th and Ts) (OKT4+ and OKT8+). The DAP-IV activity about ten times less was found in the pathological cells with a phenotype of mature Th (Sezary disease), as well as in the cells expressing antigens of both Ts and natural killers (a rare variant of T-CLL). The same activity was also found in Ts (T gamma-lymphocytosis). The data obtained show that the differences in DAP-IV expression are connected with the differentiation step rather than with the belonging to a particular subpopulation of T-cells. DAP-IV activity, which was somewhat lower than that of T-cells, was found in B-lymphocytes of patients with B-CLL, hair-cellular leukemia, and non-Hodgkin's lymphoma. No correlation of DAP-IV activity with the level of E-cellular differentiation was observed.     

Design and synthesis of new hydroxyethylamines as inhibitors of d-alanyl-d-lactate ligase (VanA) and d-alanyl-d-alanine ligase (DdlB)

The Van enzymes are ATP-dependant ligases responsible for resistance to vancomycin in Staphylococcus aureus and Enteroccoccus species. The de novo molecular design programme SPROUT was used in conjunction with the X-ray crystal structure of Enterococcus faecium d-alanyl-d-lactate ligase (VanA) to design new putative inhibitors based on a hydroxyethylamine template. The two best ranked structures were selected and efficient syntheses developed. The inhibitory activities of these molecules were determined on E. faecium VanA, and due to structural similarity and a common reaction mechanism, also on d-Ala-d-Ala ligase (DdlB) from Escherichia coli. The phosphate group attached to the hydroxyl moiety of the hydroxyethylamine isostere within these systems is essential for their inhibitory activity against both VanA and DdlB.     

The effect of laser puncture on the functional indices of the mammalian body

Biologically active points (acupuncture points) and reflexogenic zones of Wistar rats of different age were exposed to He-Ne laser radiation with the subsequent control of acetylcholine esterase activity, electric parameters of skeletal muscles and heart, and physical activity. Laser puncture was shown to increase the sympathetic nervous system tonus which was manifested by the decreased acetylcholine esterase activity and increased heart rate. Laser puncture stimulated the growth of membrane potential and increased considerably the performance capability of animals, particularly of three-month-olds.     

The activation of the immunosorptive properties of blood during its UV irradiation at therapeutic doses

UV irradiation of donor rhesus-positive blood in apparatus, applied in Soviet hospitals for autotransfusion of UV-irradiated blood produces a 2-fold increase of the blood capacity to bind antirhesus antibodies in blood or serum from sensibilized women. The above data can be used for increase in therapeutic effect of blood exchange transfusion in children with rhesus-conflict hemolytic disease.     

Catalase and superoxide dismutase activity in isogenous bacterial strains with different degrees of radioresistance

Superoxide dismutase and catalase activity has been studied in isogenous strains of various radioresistance bacteria. In mutants Micrococcus radiodurans having defects in the systems of DNA repair the superoxide dismutase activity is lower than in cells of wild type. The changes of catalase and superoxide dismutase activity have not been revealed in investigated strains Escherichia coli differing in radioresistance. It has been concluded that the survival of bacteria exposed to ionizing radiation is determined by the effectiveness of DNA repair systems realiability of which depends on the catalase and superoxide dismutase activity.     

The relationship of the potassium transport function of human erythrocyte membranes to the structural state of the glycocalyx

The two structural-functional state parameters of erythrocyte membrane in healthy donors and ischemic heart disease patients have been compared--the potassium exchange rate constant (x), and the quantity of Alcian blue sorption capacity of glycocalyx (y). The connection between the first parameter--x--and the other one--y--has been observed in cases, when the value of the latter experienced both the seasonal oscillations (the coefficient of lineal correlation was: r = -0.87, P less than 0.01) and the changes in the cause of ischemic heart disease (r = -0.72, P less than 0.01) and its treatment (the coefficients of correlation attitude of each of parameter changes were: eta xy = 0.83, P less than 0.01; eta yx = 0.52, P less than 0.05). The above connection may indicate the participation of membrane glycoproteins and glycolipids in a regulation of the cation transport function of the erythrocyte membrane.