Idiotype-specific inactivation by xenogeneic antisera of T killers but not of T-MIF producers immune to H-2 complex antigens

Following appropriate absorption rabbit serum to CBA anti-C57BL/6 lymph node cells (rabbit ISS) and rat serum to enriched CBA anti-C57BL/6 T killers (rat ISS) selectively inhibited the activity of K-anti-b T killers but did not affect T killers of other specificities (K-anti-d, d-anti-b). Rabbit ISS did not suppress the capacity of CBA anti-C57BL/6 (K-anti-b) T cells to produce MIF. Under the same conditions, anti-Thy-1.2 serum inactivated killers and K-anti-b MIF-producers. The findings indicate that the killers and MIF-producers immune to the antigens of H-2 complex constitute different subpopulations of T cells, which appear to carry nonidentical sets of idiotypes.     

Relation of double-stranded DNA breaks and their repair to cell death and recovery after methylnitrosourea exposure

The yield of DNA double-strand breaks (DSB) in the cells of mouse lymphosarcoma treated with nitrosomethylurea (NMU) was registered by means of elastoviscosimetry. It was shown that after short-term (7 min) treatment with NMU the lesions formed in DNA are efficiently repaired both in complete and conditioned media. After long-term (30 min) treatment DNA was only repaired in complete growth medium. The yield of the first fixed DSB after long-term NMU treatment correlated with the mean lethal dose D0. After short-term NMU treatment the first DSBs are registered in the dose range which is 4-fold higher than D0. The nature of lethal and potentially lethal lesions as well as the participation of various repair systems in the elimination of potentially lethal lesions are discussed.     

Epidemiological analysis of hepatitis A morbidity

A retrospective epidemiological analysis of hepatitis A morbidity for many years among the population of two neighboring towns in the temperate climatic zone of the USSR has revealed the cyclic character of the epidemic process without a perceptible decrease in its extensiveness and has determined the high-risk groups, as well as the beginning of the seasonal rise of morbidity in these groups. The results of the study indicate that different levels of hepatitis A morbidity and risk groups can be observed in these two neighboring towns. At periods of a lower morbidity level the high-risk group embraces schoolchildren, and when morbidity is at a higher level the risk group includes schoolchildren and preschool children in organized groups. Among the latter the morbidity level is influenced by factors acting all the year round and among school children, by seasonal factors. The beginning of the seasonal rise of morbidity falls on August, while in organized groups of children of preschool age the seasonal rise of hepatitis A morbidity begins 1-1.5 months later. All prophylactic measures for controlling hepatitis A should be carried out with due regard to these features of the epidemic process.     

Vitamin E and its structural analogs in tuberculosis]

Efficiency of tocopherol, its analog with a shortened side chain as well as their quinons for tuberculosis was determined. All the studied compounds inhibited peroxide-formation processes in the liver homogenate and mitochondria. The vitamin E amount in the blood is considerably decreased in case of tuberculosis. The studied analogs increased its content and possessed a weak tuberculostatic but expressed antiedemic and antiinflammatory action. Administration of vitamin E in combination with isoniazid to sick animals had a favourable effect on the processes of tissue respiration and oxidative phosphorylation. If taking a sum of characters, tocopherol acetate with a shortened side chain is the most efficient of all the analogs under study for the tuberculosis therapy.     

Production of factors regulating macrophage motility in the early stages of mixed lymphocyte culture

The macrophage migration stimulation factor (MSF) is produced during the first hours of mixed lymphocyte culture (MLC) in the H-2 system. The activity of MSF is characterized by sharp peaks of migration stimulation in the culture fluids of allogeneic MLC. The peaks appeared every 5 hours. After 12--16 hours in the culture fluids of allogeneic MLC, there has been demonstrated macrophage migration inhibition factor whose activity rose by 48 hours. Optimal concentrations were revealed for stimulation and inhibition of macrophage migrations on the dilution of 1--2-day MLC culture fluids. The existence of the biorhythmical mechanism that controls the macrophage mobility through the balance of soluble mediators with alternative activity is suggested.     

Mutagenic effects of gamma-rays on plasmid DNA in Escherichia coli

A purified and dried DNA of plasmid pKO482 (galK+) is 10 times more resistant to the inactivating action of 60Co-gamma-rays than that of lambda phage. gamma-Irradiation of the plasmid DNA induces forward mutations of galK, the frequency of which increases linearly with the dose. The efficiency of the mutagenic action of gamma-rays on the plasmid galK locus is 10(-12) per 1 rad and per 1 base pair. The mutagenic effect of gamma-radiation but slightly depends upon bacterial recA+ gene and upon the SOS-repair system induced by UV-irradiation of the recipient cells. It is assumed that the premutational lesions induced in the purified DNA by the direct effect of gamma-radiation are fixed into mutations by misreplication.     

Induction of the SOS-like system in Rec-mutants of Bacillus subtilis]

Influence of the recE1, recB2, recB3, recB19, recF15, recF18, recL16, recM13 and recM27 mutations of the induction of the SOS-like system component, i. e. the RecE protein of Bacillus subtilis was studied by RIA-dot-blot method in UV-irradiated or treated by nalidixic acid cells. These agents caused a significant increase in the wild type (rec+) cells but did not stimulate the RecE synthesis in the rec mutants tested. The two exceptions were recB2 and recF18 mutants treated by nalidixic acid. The tsi23 mutation caused thermoinduction of phi 105 bacteriophage in the rec+ genetic background while no prophage particles were induced in the recE, recF, recL, recM mutants. The data suggest that the genetic damage of several rec genes including recB, recE, recF, recL and recM can block induction of the SOS-like system of Bacillus subtilis.