Deoxyribonuclease activity in the tissues of X-ray irradiated animals with alloxan diabetes

Fractionated X-irradiation (a cumulative dose of 12.9 mC/kg) of animals with alloxan diabetes caused different, with respect to direction and degree, changes in liver nuclease system than those observed in intact animals after similar irradiation. This indicates that insulin is involved in a metabolic response of the organism to irradiation with relatively small doses.     

Effect of external gamma radiation on shortening the life expectancy and rates of the formation of absorbed doses from incorporated 239Pu in dogs

External gamma irradiation of dogs with doses of 103.2 and 51.6 mC/kg combined with the effect of inhaled plutonium-239 accelerates the formation of absorbed doses in secondary organs of the radionuclide deposition by 41.7 and 2.4 times, respectively, whereas the dose of 25.8 mC/kg is ineffective. As estimated by the rate of 239Pu accumulation and by the life span shortening, the minimum effective and the maximum ineffective doses are 104.8 and 80.5 cGy and 89.2 and 79.2 cGy, respectively.     

Effect of sodium humate on animals irradiated with lethal doses

A therapeutic effect of natrium humate given to experimental mongrel rats exposed to 60Co-gamma-radiation of lethal doses has been studied. A single administration of natrium humate, 5-10 min following irradiation with a dose of 193.5 mC/kg (LD100/30) leads to a 43.3 per cent survival of animals after 60 days; with a dose of 232.2 mC/kg (LD100/8) there is a trend toward the increase in the life span of exposed rats.     

Regularities in forming chromosome aberrations in cattle lymphocytes in external and combined radiation exposure

Aberrations in lymphocytes of cattle blood exposed to gamma-radiation and combined radiation were found. It was shown that seven days after the exposure to doses from 64.5 to 103.3 mC/kg a number of aberration varied in the range from 16.1 to 37.7 per 100 cells, whereas a frequency of aberrated cells was from 13.5 to 29.8. After the exposure to 77.3 mC/h and the following inclusion of fused radioactive particles into the fodder (48.1-762.2 Mbq/kg of the live weight), the number of aberrations increased from 25.5 up to 55.0 per 100 cells and the number of aberrated cells increased from 21 up to 43%.     

A rapid for cumulative chromosomal damage in mice: Accumulation of circulating micronucleated erythrocytes

The frequency of micronuclei in normochromatic peripheral blood erythrocytes was found to be a useful index of cumulative chromosomal damage in repeatedly exposed mice. Although approximately 5 weeks of continuous treatment is required to reach the maximum steady state level, significant elevations in this index were achieved after only 5 daily exposures to non-lethal doses of all six genotoxins tested. The frequencies of micronucleated cells per 1000 normochromatic erythrocytes in weanling mice after 5 daily intraperitoneal (i.p.) injections of each test agent were: triethylenemelamine (0.5 mg/kg), 13.7; mitomycin C (2 mg/kg), 7.1; cyclophosphamide (22 mg/kg), 6.6; colchicine (1 mg/kg), 4.0; nitrogen mustard (0.4 mg/kg), 3.6; 7,12-dimethylbenz[a]anthracene (5 mg/kg), 6.6. Controls averaged 1.2 per 1000. During extended exposure to nitrogen mustard (5 i.p. injections of 0.4 mg/kg per week), the incidence of micronucleated erythrocytes rose steadily to a value of 12.0 per 1000, approaching the steady state after about 5 weeks of treatment. These results indicate that the measurement of micronuclei in peripheral blood erythrocytes is an effective and rapid method for estimating chromosomal damage in subchronically or chronically exposed animals. In practical application, routine blood smears taken during 90-day subchronic toxicity tests could be scored for micronuclei in less than 1 day, providing an economical estimate of in vivo chromosomal damage.     

Release of myoglobin in the blood of irradiated swine showing decreased activity of various enzymes--markers of muscle tissue injury

Dynamics of changes in the level of myoglobin, hematological indices, and activity of certain enzymes (lactate dehydrogenase, hydroxybutyrate dehydrogenase, and creatine phosphokinase) was studied in blood of exposed (103.2 mC/kg) pigs. As the activity of enzymes decreased the myoglobin content of blood increased 5-7 days following irradiation. The effect of radiation was shown to promote the development of hypoxia in the animal body which was indicated by the ECG changes, the release of functionally deficient erythrocytes to blood, and the occurrence of stable vast hemorrhages.     

Effect of irradiation on the regulatory function of B-lymphocytes

A study was made of the effect of irradiation of B-lymphocytes with doses of 0-464.4 mC/kg on their regulatory function in activating the allogenic haemopoietic stem cells of mice. Irradiation changed the function of B-lymphocytes leading to transformation of their helper effect into the suppressible one. The parameters of the radiation damage to B-lymphocytes-regulators were determined.     

Cholinergic processes as affected by small doses of radiation on the host

Acetylcholine content of blood and cholinesterase activity in blood and tissues of albino rats were studied at different time-intervals after gamma-irradiation with doses of 12.9 and 25.8 mC/kg. Cholinergic processes were found to change with the development of radiation dose.     

Effect of radiation on cell interactions in the phenomenon of non-syngeneic stem cell inactivation. Changes in B-lymphocyte function after irradiation

A study was made of the changes in the mode of interaction between T- and B-lymphocytes of mouse lymph nodes with respect to the phenomenon of inactivation of non-syngeneic haemopoietic stem cells. It was shown that irradiation of B-lymphocytes with doses of 77.4--232.2 mC/kg changes their helper activity into a suppressor activity with regard to T-cell-killers having a low electrophoretic mobility.     

Combined effect of 239Pu and external gamma radiation on pregnant and lactating rats

Exposure of pregnant and lactating rats to external gamma-radiation (12.9-103.2 mC/kg) caused 239Pu redistribution within their bodies. The increase in the transfer of 239Pu to the progeny was maximum after gamma-irradiation of pregnant rats with the dose of 25.8 mC/kg. The decrease in the intake of 239Pu by the progeny was maximum after gamma-irradiation of lactating rats with the dose of 12.9 mC/kg. With the combined effect of gamma- and alpha-radiation gamma-radiation was shown to play the major role in the embryos death.     

Effect of ionizing radiation on the kinetic parameters of rat cerebral cortex Na, K-ATPase

A study was made of the effect of ionizing radiation of 10.3 and 180.6 mC/kg on kinetic parameters of the processes of activation of Na,K-ATPase of rat brain cortex by Mg-ATP-substrate and Na+ and K+ ions. The obtained results prompt an assumption that a conformational rearrangement occurs under the effect of ionizing radiation which is not identical after relatively small and lethal radiation doses.     

Morphofunctional state of vascular wall components in the rat brain following gamma-irradiation of the head

The histochemical methods were used to study alkaline phosphomonoesterase of capillaries, glycosaminoglycanes of vascular walls, and tissular basophils of rat brain after local gamma-irradiation of the head with doses of 51.6-645 mC/kg. During the first minutes and hours after irradiation, the actively functioning capillary network lengthened and secretion of indolylamines by tissular basophils increased. It is assumed that the changes observed are compensatory.     

The genotoxic and cytotoxic effects of ribavirin in rat bone marrow

The genotoxic and cytotoxic effects of the antiviral drug, ribavirin, was studied in rat bone marrow by employing the micronucleus assay. Ribavirin in doses of 10, 15, 20, 30, 50, 75, 100 and 200 mg/kg, and cyclophosphamide (CP) 40 mg/kg (only for sex-difference study) were injected intraperitoneally. Bone marrow was collected at 24 h and 48 h following the injection. To evaluate the recovery, the bone marrow was also sampled at 72 h from 20, 100 and 200 mg/kg treated rats. The micronucleus assay was conducted according to the standard procedure. Ribavirin elevated the incidence of micronuclei (except 10 mg/kg) in erythrocytes (P<0.01). The micronucleated polychromatic erythrocytes showed the initial steep increase at 15 and 20 mg/kg dose level, then with the gradual increase, possibly due to the limited metabolism and action of higher doses. The incidence of micronucleated normochromatic erythrocytes was not dose dependent. The effect was more at 48 h than 24 h due to prolonged toxicity of the drug or its metabolites, and by 72 h, recovery was observed eventhough the genotoxicity was significant. The PCE% decreased as the dose was increased up to 75 mg/kg, then without much difference between two higher doses. Only 100 mg/kg ribavirin and CP showed more toxicity on male rats. Cytotoxicity was seen due to hindered erythropoiesis or cell destruction. Our findings suggest that ribavirin is genotoxic and cytotoxic agent for rat bone marrow.     

Evaluation of cell membrane permeability for Ca2+ and adenylate cyclase in sheep peripheral blood cells,exposed to low doses of radiation

Chronic irradiation of sheep with doses of 2.6 and 12.9 mC.kg was characterized by the modification of the adenylatecyclase activity and Ca2+ permeability of plasma membrane in cells of the peripheric blood, with no changes in the clinical and hematological indicators. The observed effects are assumed to result from structural and dynamic variations in the lipids of membranes.     

The effect of diphenylhydantoin on the frequency of micronuclei in bone-marrow polychromatic erythrocytes of mice

Using the micronucleus test to evaluate the mutagenic effect of 5,5-diphenylhydantoin (DPH) on bone marrow polychromatic erythrocytes, male Balb-C mice were treated with the drug in single and multiple injection tests. A significant increase in the frequency of micronucleated polychromatic erythrocytes (MPE), P less than 0.05, was found when the mice received a single injection of DPH at doses of 0.5 and 1.0 mg/kg, and this frequency did not increase at higher doses. When mice were treated 3 times, at 24-h intervals, with 1.0 mg/kg of DPH, a significant increase in MPE was also observed (P less than 0.05) but this was lower than when they received a single injection of the same dose. A cytotoxic effect of NaOH, 0.1 N, which was used as solvent, was also observed either when alone or when DPH (1.0 mg/kg) was injected 3 times. This effect was comparable to the one produced by mitomycin C (MMC) at a dose of 0.5 mg/kg.     

Cytogenetic effects of Cuman L, a dithiocarbamate fungicide

Cuman L, a dithiocarbamate fungicide, was assessed for its effects in the germ cells and the bone marrow erythrocytes of Swiss Albino male mice. The 3 sublethal doses of 350, 700 and 1050 mg/kg b.w. of Cuman L induced a significant (P less than 0.01) increase in the number of chromosomal aberrations in the germ cells. A significant increase (P less than 0.01) in the percentage of micronuclei in the erythrocytes was also induced by the three doses.     

The reaction of free cellular elements of the lungs to gamma exposure

A quantitative composition of free cell elements and morphology and mitotic activity of macrophages were studied after gamma irradiation with doses of 25.8, 77.4, and 180.6 mC/kg. Morphological changes in the lungs and a deviation from the control values of an overall content of cell elements in washings were found to be a function of radiation dose. The discrepancy between the results obtained by other authors are attributed to a limited elimination of macrophages due to pulmonary edema and restoration of the number of macrophages due to a relatively moderate mitotic activity of these cells.     

Effect of gamma-irradiation on the enzyme activity of cerebrospinal fluid lymphocytes in dogs

Cytochemical activity of succinate dehydrogenase (SDG), L-glycerophosphate dehydrogenase (L-GPDG), lactate dehydrogenase (LDG), and glutamate dehydrogenase (GDG) increased immediately after total-body irradiation with a dose of 129 mC/kg. After 2 h, LDG activity only returned to the control level. Irradiation of the head with the same dose caused less pronounced changes. Changes caused by lethal irradiation (1290 mC/kg) were different: there was an increase after exposure of the abdomen and a decrease in the activity of SDG and L-GPDG after irradiation of the head.     

Administration-route-related differences in the micronucleus test with benzene

The effect of route of administration on the outcome of the micronucleus test was studied in 2 laboratories by administering the model chemical benzene intraperitoneally (i.p.) and orally (p.o.) to 2 strains of mice: MS/Ae and CD-1. On the basis of results obtained in a small-scale acute toxicity study and in a pilot micronucleus test, full-scale micronucleus tests were performed with a 24-h sampling time at doses of 250, 500, 1000, and 2000 mg/kg i.p. and 500, 1000, 2000, and 4000 mg/kg p.o. In both strains of mice, a higher incidence of micronucleated polychromatic erythrocytes (MNPCEs) was observed after p.o. administration. The ratio of polychromatic erythrocytes (PCEs) to total erythrocytes decreased more markedly at higher doses i.p. in both strains. Thus, benzene induced more micronuclei via the p.o. route, while inhibitory effects on bone marrow cells were stronger after i.p. administration.     

Genotoxicity of 2-[2-(acetylamino)-4-[bis(2-hydroxyethyl)amino]-5-methoxyphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-6) and 4-amino-3,3'-dichloro-5,4'-dinitro-biphenyl (ADDB) in goldfish (Carassius auratus) using the micronucleus test and the comet assay

2-[2-(Acetylamino)-4-[bis(2-hydroxyethyl)amino]-5-methoxyphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-6) and 4-amino-3,3'-dichloro-5,4'-dinitrobiphenyl (ADDB) are two compounds, which show strong mutagenicity toward bacteria, that have been identified as major mutagens in river water in Japan. In the present study, we examined the genotoxicity of PBTA-6 and ADDB in goldfish (Carassius auratus) by the micronucleus test and single-cell gel electrophoresis (comet assay). The frequencies of micronuclei in gill cells gradually increased until 96h after i.p. injection of PBTA-6 and ADDB at doses of 50mg/kg body weight, and then decreased 144h after injection. PBTA-6 induced micronuclei in gill cells dose-dependently at a dose range of 1-100mg/kg body weight, giving significantly high frequencies at doses of 50 and 100mg/kg body weight. On the other hand, no significant increase was observed in the peripheral erythrocytes of goldfish exposed to PBTA-6 or ADDB. In the comet assay, values of DNA tail moment and tail length in peripheral erythrocytes increased significantly until 6h after the i.p. injection of PBTA-6 (50mg/kg body weight), only to decrease by 9h after injection. Both the DNA tail moment and tail length were dose-dependently increased by injections of PBTA-6 at doses ranging from 1 to 50mg/kg. Significantly high values for tail moment and tail length were found in peripheral erythrocytes 3h after an i.p. injection of ADDB and persisted for up to 6h. These results show that both PBTA-6 and ADDB have genotoxic effects in goldfish.