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The administratio prior to irradiation of adenosine triphosphate (ATP) or other adenosine nucleotides, singly or in combination, increased the radioresistance of mice. Post-irradiation treatment with the adenosine nucleotides had no effect on the survival of the irradiated mice. Dose reduction factors of 2.32 could be obtained by pretreatment of mice with the following combination of protective agents: S-2(4-aminobutylamino)ethyl phosphorothioic acid(WR 2822), cysteamine (MEA) and ATP. Since cyclic AMP levels were unchangd in the spleen or gut by administration of cysteamine and other protectors it is unlikely that the increase in preotection was due to changes in cyclic AMP levles. The calcium salt of ATP provided a higher level of protection than the ATP alone, indicating that the protective mechanism of ATP is probably not related to anoxia.
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The radioprotective effect (RPE) of some arylalkylamines (AAAs) was studied in experiments on mice. Mesaton and its close analogues were injected subcutaneously 15 minutes prior to irradiation at a dose of 800 rad. The protective effect is exerted by AAAs in low doses (25--50 mumole/kg), the compounds show stable and high RPE (80--80% survival, dose reduction factor being 1.3--1.4) and low toxicity (LD50 = 4--8 mumole/kg). AAAs studied are not less effective than aminothiols. Their pharmacological spectrum--K = LD50/ED50 (200--500) is superior to that of known aminothiols and indolylalkylamines.
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The effect of Fenchlorphos on postirradiation changes of serum protein levels and nucleic acid content in rat liver were investigated. It was found that this compound significantly decreases postirradiation changes in serum proteins, properdin level and nucleic acid content in rat liver. An important role of these phenomena in radioprotective action of Fenchlorphos is suggested.
The purpose of this investigation is to find out whether streptomycin and the related compound dihydrodeoxystreptomycin have any mutagenic effect and whether they both are capable of recovering X-ray induced chromosomal translocations in mouse spermatogonia of directly treated animals and their progeny of the first generation. The cytological findings show the absence of any mutagenic effect in animals nonirradiated and treated with streptomycin and dihydrodeoxystreptomycin. The frequency of chromosomal translocation after total irradiation was 9,07%; in animals treated with streptomycin following irradiation 5.13%, and in those irradiated and treated with dihyrodeoxystreptomycin, 3.70%. Male offsprings, originated from parents treated only with antibiotics show no chromosomal translocations. However, offsprings originated from irradiated and treated parents gave birth to the male offspring with chromosomal translocations.
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The SH-groups of alpha-mercapto-propionylglycine (MEPRIN) are remarkably stable in diluted solution either at room temperature or at 50 degrees C, even if storing takes place under air-bubbling. The SH-activity was measured by polarographic method and amperometric titration. Neutralization of the carboxyl group decreases the stability of the sulfhydryl groupings. Evaporation of neutralized solution leads to a 30--50 per cent decrease of SH-activity. Lyophilization reduces this loss by 10--15 per cent. Neutralization is best carried out in the absence of oxygen; in this case, 94 per cent of the sulfhydryl activity will persists, irrespective of the pH. The dissociation constant of MEPRIN-SH is pK' = 8.47. The SH-stability of the product is satisfactory when neutralized in nitrogen atmosphere to pH 3--5; a loss of only 5 per cent can be expected after storing in an oxygen-free 10(-3) molar solution for 144 hours. Between pH 6 and 8 this value is 31 per cent on the average, while at pH 9 it is more favorable again.
The effect of polyriboguanylic-polyribocytidylic acid complex was investigated against acute X- and prolonged 60Co-gamma irradiation. Prophylactic administration of the polyribonucleotide complex increased endogenous spleen colony formation and the percentage of survival of irradiated BALB/c mice. The most pronounced effect was observed when the animals had been irradiated at the time of maximum interferon accumulation in blood, i.e. 24 hr after interferon induction by the polyribonucleotide complex.
Comparative studies of antioxidative effects of phenole inhibitors (vitamine E) amino-and sulfur-containing radioprotectors, and chemical cancerogens on oxidation of unsatured fatty acid were carried out. Some polycyclic hydrocarbons and azo-compounds produce a prolonged and stable decrease of peroxide accumulation rate in oxidized oleic acid. Due to this property in the in vivo systems chemical cancerogenes can induce prolonged stable changes in the parameters of vitally important redox processes.
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