Mechanism of the antimutagenic action of interferon: the capacity to protect the human cellular repair system

It has been shown that premutagenic treatment with leukocytic interferon (10, 100 IU/ml) of human peripheral blood lymphocytes cultivated in vitro at the G1-stage of the mitotic cycle results in different cell response to gamma-radiation in doses of 0.5, 1, 2, 4 Gy according to chromosome aberration. The antimutagenic effect failed to be attained with the doses 0.5 and 1 Gy, being maximal at the dose 2 Gy. According to sister chromatid exchanges (SCE) cell pretreatment with interferon leads to a reduction in the effect of gamma-radiation at the dose 2 Gy to the level obtained in the cells after exposure to interferon. In experiments with 4-nitroquinoline-I-oxide, there was a significant decrease in the number of SCE in interferon-treated cells.     

Mechanism of the antimutagenic action of dibunol

In experiments with cultured V-79 Chinese hamster cells a study was made of the influence of dibunol on the level of gamma-radiation-induced micronuclei and sedimentation properties of cell nucleoids during ultracentrifugation in a neutral sucrose gradient. Protection of DNA molecule against the effects of both primary and secondary damages was found to be involved in the mechanism of the protective action of dibunol.     

The oligodendrocyte and its many cellular processes

The oligodendrocyte (OL) is increasingly providing a model system for probing central issues of cell biology. During development, OL progenitors undergo controlled migration, proliferation and differentiation, secrete and respond to a number of growth factors, and dramatically change their cellular architecture, culminating in the formation of the myelin sheath. This review examines some facets of the OL that make it an especially attractive tool for studying many basic questions in cell biology.     

The mitostatic and lymphotoxic action of kemantane and its effect on B-suppressors]

The in vivo study of the influence of Kemantan on the growth of endogenous colonies in the spleen of sublethally (6 Gy) irradiated (CBA x C57BL/6J) F1 mice (mitostatic action) and on the capacity of transplanted lymphocytes of CBA mice for suppressing their multiplication (lymphotoxic action) was carried out. Besides the capacity of Kemantan for affecting the induction, formation and functioning of B-suppressors of antibody formation was studied. As revealed in this study, Kemantan in doses of 0.2-200 mg/kg did not produce a mitostatic and lymphotoxic effect and had no influence on the realization of the suppressing action of mature B-suppressors. In doses of 20 and 200 mr/kg Kemantan, injected to donors at the phase of the induction and accumulation of B-suppressors, abolished their formation.     

A cytogenetic analysis of the antimutagenic action of alpha-tocopherol on spontaneous and radiation-induced chromosomal mutations]

The antimutagenic effect of alpha-tocopherol at concentrations of 1-10(-5)-1-10 mcC/ml was studied with respect to spontaneous and radiation-induced chromosome mutations in Allium fistulosum L. and Vicia faba L. It is established that at these concentrations alpha-tocopherol exhibits a significant antimutagenic activity, decreasing the frequency of chromosome mutations more than by 40-50%. No changes resulting from the antimutagenic effect of alpha-tocopherol were observed in the spectrum of structual mutations of chromosomes.     

The mannitol cycle--a new metabolic pathway in the Coccidia

A new metabolic pathway, known as the mannitol cycle, has been identified in the coccidian parasite Eimeria tenella. It appears that this pathway may be important for the production and utilization of energy reserves for the parasite. This pathway has not been found in any other animal system and was previously thought to be unique to fungi.     

The effect of cocaine on the central action of noradrenaline]

Cocaine influence on the central action of noradrenaline was studied in experiments on rabbits by the method of impulse summation. Cocaine was shown to increase the noradrenaline action of the central nervous system. Thus, cocaine intensified not only the peripheral effects of noradrenaline (this was known before), but its central action as well.     

Localization of the metabolic processes affected by calcium during corticotropin action

To define the role of calcium during corticotropin-induced steroidogenesis, adrenal sections were incubated under conditions of varying degrees of calcium depletion. Corticosterone production, [¹⁴C]leucine incorporation into protein, and tissue cyclic AMP levels were measured concomitantly. Omitting calcium from the incubation inhibited all three processes to variable extents, thus limiting conclusions regarding which process is most dependent on calcium.While calcium was required during the early phase of corticotropin action, it was not required during later phases; rapid induction of calcium defiency did not diminish the heightened rate of steroidogenesis previously induced by corticotropin in the presence of calcium. Thus, while calcium is required for induction of steroidogenesis factor(s), the operation of the latter is not dependent upon calcium in the extracellular fluid.     

The antimutagenic activity of compounds of modified polyglucin]

The effect of modified polygluquin compounds on gamma-irradiated nuclei of V-79 Chinese hamster cells has been studied. Antimutagenic properties of the compounds are determined by aldehyde groups and oxidized chains.     

The effect of calcium antagonists on blood deoxygenation processes]

The effect of verapamil, nifedipine and sensit on the whole rat blood deoxygenation was studied by polarographic coulometry with consequent calculation of deoxygenation rate (DR) and blood deoxygenation constant (BDC). These drugs were studied in concentrations 10(-8)-10(-4) M according to their therapeutic range in vivo. Both verapamil and nifedipine significantly decreased DR, and the latter drug decreased BDC as well in concentration 2.9.10(-7) M. In contrast to verapamil and nifedipine, sensit caused mild, but statistically significant dose-related increase in DR with concomitant decrease in BDC. The data presented failed to establish relationships between chemical structure and deoxygenative effect of the drugs. Deoxygenation effect of sensit favours its administration in the treatment of ischemia-related arrhythmias.     

Herbicidal effect on some metabolic processes of Azotobacter chroococcum

The effect of pyramin (1-phenyl-4-amino-5-chloro-piridazone-6) and venzar (3-cyclohexyl-5,6-trimethyleneuracil) on growth, oxygen uptake and nitrogenase activity was examined. The possibilities of herbicide accumulation in cells and binding by mucopolisaccharides were also tested. Stimulation of growth was observed in the presence of pyramin (20 and 100 ppm) but no influence of venzar was found. Venzar was found to penetrate into the cells. Pyramin did not penetrate into the cells but its content decreased in cultures of Azotobacter strains. However, no degradation products of pyramin were found. Pyramin was detected in mucopolisaccharide fractions in range 0.2-47 micrograms of Pyrazon per 100 mg. Pyramin and venzar reduced the acetylene reduction rate of crude extracts by 50% when doses of active substances were equal to the weight of crude extract protein contents. Doses required for similar effect in living cells were however more than fourteen times higher. Addition of polivinylpyrrolidone and albumin protected the N2-ase from negative effect of pyramin and to a lesser degree from that of venzar.     

The biological action of chromium in relation to its valency]

The biological action of chromium in the human or animal organism depends on valency: normal physiological activity is displayed at the expense of CrIII, but toxic activity is more characteristic of CrVI. In the digestive tract and pulmonary tissue CrVI may restore in CrIII.