The effect of exposure to 60Co accelerated electrons and gamma quanta on the activity of oxidative and hydrolytic enzymes in the rat brain]

In experiments with 112 male Wistar rats it was shown that accelerated electrons (85 Gy) caused a significant increase in activities of succinate dehydrogenase (SDG) by 15.8% and lactate dehydrogenase (LDG) by 17.0%, and a decrease in activities of alkaline phosphatase (AP) and monoamine oxidase (MAO) by 10.6 and 7.8% respectively within the sensorimotor region of the cerebral cortex immediately after irradiation. Activity of SDG and MAO decreased (by 16.4% and 7.8% respectively) in the caudate nucleus over the same period of time. An increase in the accelerated electron dose from 85 to 500 Gy did not change the direction and the rate of the radiation response of the enzymes. Exposure of rats to 60Co gamma quanta (75 Gy) increased SDG and LDG activity (by 21.4 and 17.3% respectively) within the sensorimotor cortex as late as 10 min after irradiation. A repeated significant increase in SDG and LDG activity was observed 2 hr after irradiation.     

Effect of adrenaline on the succinate dehydrogenase activity of peripheral blood lymphocytes of rats following exposure to ionizing radiation

In experiments with albino mongrel female rats, the influence of adrenaline on succinate dehydrogenase (SDG) activity in the peripheral blood lymphocytes of irradiated and intact animals has been investigated. Two minutes after the intraperitoneal administration of adrenaline (1 mg/kg) to intact rats SDG activity sharply rises and 3-4 min it drastically falls. In 6 to 8 min the second peak in the enzyme activity is registered. Twenty minutes after irradiation of rats in the cranio-caudal direction with a dose of 75 Gy delivered to head, the reaction to adrenaline, manifested by the rise in SDG activity, is absent.     

Intestinal ischemia-induced changes in the activity of NADPH-d and energy metabolism enzymes in rat myenteric and splanchnic plexus

The changes in the activity of NADPH-d and energy metabolism enzymes, lactate dehydrogenase (LDG) and succinate dehydrogenase (SDG), in the neurons of splanchnic and myenteric plexus (SP and MP, respectively), induced by 1-h-long ischemization of a part of the small intestine, were studied using cytophotometric technique; the measurements were performed under conditions when synthesis of nitric oxide (NO) was either blocked or activated. The activity of NADPH-d, SDG, and LDG in MP neurons was shown to be enhanced by ischemia. In SP neurons, the LDG activity increased, while the NADPH-d and SDG activities did not change. The blockade of NO synthesis with nitro-L-arginine methyl ester was followed by a decrease in the NADPH-d level in SP and MP neurons, but was maintained at a level lower than the control one during ischemia. Administration of L-arginine, the NO precursor, increased NADPH-d activity in MP and SP neurons, while at ischemization of the intestine this activity remained at a level higher than in the control. It is concluded that NO-ergic mechanisms (mostly at the MP level) are significantly involved in regulation of the functions of the small intestine in ischemia.     

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 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.     

Postradiation disorders in the adenine-phosphoribosyltransferase pathway of AMP biosynthesis

A study was made of the activity of adenine-phosphoribosyltransferase (EC 2.4.2.7), which catalizes the biosynthesis of AMP from adenine and 5-phospho-alpha-D-riboso-1-diphosphate, in extracts from thymus and liver during 24 h following irradiation of mice in a dose of 245.1 mC/kg (dose-rate of 9.16 X 10(-4)-9.0 X 10(-4) A/kg). Adenine-phosphoribosyltransferase activity of liver remains normal during the entire period of observation. In thymus extracts, the activity of the enzyme decreases down to 70-80% of the control level 3 h after irradiation, it is normalized after 6 h and increases up to 150-160% of the control level by the end of the first day of radiation sickness.     

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.     

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.     

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.     

Changes in the activity of the oxidative and hydrolytic enzymes of the animal cerebral cortex in the early periods after gamma irradiation and the use of meksamine and the synthetic analog of prostaglandin F2 alpha-estrofan

In experiments with (CBA x C57B1/6)F1 mice it was shown that LDH activity moderately increased 5 min after exposure of the head to 200 Gy gamma radiation. After 60 min, there was a 24.4 per cent decrease in alkaline phosphatase activity and a 24.3 per cent increase in SDG activity. Injected prior to irradiation meksamine precluded the postirradiation increase in SDH and alleviated the postirradiation decrease in alkaline phosphatase.     

Changes in the level of pyrimidine nucleoside phosphates in the liver of irradiated rats

Content of uridyl and cytidyl nucleoside-phosphates in the liver of rats irradiated by gamma-rays (60Co) in a dose of 774 mC/kg (3000 P) was studied 0.5, 1, 3, 6 and 24 h after the effect. A trustworthy decrease of UTP and CTP as well as UDP and CDP content 24 h after irradiation was found. The number of pyrimidine nucleoside monophosphates increases after 24 h of the effect.     

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.     

Catabolism of pyrimidine nucleotides in the liver of irradiated animals

A study was made of the activity of nucleoside diphosphatase (NDPase, EC 3.6.1.16) and nucleoside triphosphatase (NTPase, EC 3.6.1.15) that catalyze enzymatic dephosphorylation of UDP, CDP, UTP, and CTP in mitochondria and postmitochondrial supernatant fraction of rat liver 30 min, 1, 3, 6 and 24 h following 60Co-gamma-irradiation with a dose of 774 mC/kg. The observed phase changes in the enzyme activity depended on the times of exposure, a cell fraction, and nucleotides under study. Both uridylic and cytidylic nucleotides exhibited a significant increase in the their enzymatic disintegration being more pronounced at a comparatively later times, that is, 6 h, and particularly, 24 h after irradiation.     

Dynamic analysis of the induction of chromosome aberrations in the bone marrow cells of laboratory mice

A study was made of the incidence of such damages as breaks, gaps, and exchanges occurring in bone marrow cells of CBA mice after irradiation with a dose of 12.9 mC/kg. Males and females exhibited a similar spontaneous chromosome aberration level. Nevertheless, the experimental results obtained indicate that males are more radiosensitive than females.     

Effect of low-level chronic x-rays on the hemolytic stability and population composition of peripheral blood erythrocytes

A study was made of the haemolytic stability and population composition of peripheral blood erythrocytes of rats chronically exposed to X-radiation of 0.258 mC/kg/day during 30 days. Haemolytic stability of erythrocytes changed at cumulative doses of 2.58, 5.16 and 7.74 mC/kg. Percentage of some erythrocyte fractions obtained by fractionation in a sucrose density gradient was found to change after irradiation with cumulative doses of 5.16 and 7.74 mC/kg.     

Early effects of the influence of ionizing radiation in relatively small doses on the neuromediator systems responding to the central regulation of the hypothalamo-pituitary-adrenal cortex system

In experiments with mature Wistar male rats changes of mediator interrelations in different brain parts, responsible for the central regulation of the hypothalamo-pituitary-adrenocortical system, were detected at early times after whole-body X-irradiation with a dose of 12.9 mC/kg. These changes represent one of the major mechanisms leading, at later times after irradiation, to the development of syndromes related to diencephalic disturbances.     

Sex behavior of male rats after gamma-irradiation: various radiobiological characteristics

The authors showed a pronounced and stable decrease in sexual motivation of male rats immediately after gamma-irradiation of the head with a dose of 2.58 C/kg. Exposure of the body to 1.29-2.58 C/kg radiation also inhibited sexual behaviour but only by the 45th-55th minute following irradiation: with higher doses some increase in sexual activity was observed immediately after irradiation.     

Quantitative histoenzymological characteristics of the myocardium in sudden cardiac death

Enzymes in the human myocardium following sudden death were examined for activity in a quantitative histoenzymological study, these were NAD-dependent dehadrogenases of succinate (SDG), lactate (LDG), beta-hydroxybutyrate (beta-HOBDG), alpha-glycerophosphate (alpha-GPDG), alcohol (ADG), glucoso-6-phosphate (G-6-PDG), and NAD-diaphorase (NADse), and catalase. Autopsies were performed within 3 h after death. beta-HOBDG and LDG were found to show an increase in activity in the cardiomyocytes of sudden death subjects with coronary heart disease without apparent changes. In the myocardium from death subjects with coronary heart disease and large postinfarct cardiosclerosis, the activity of the enzymes was directly related to the severity of myocardial hypertrophy and signs of chronic heart failure. As myocardial hypertrophy developed, the enzyme activity increased; when there appeared signs of chronic heart failure it decreased. The myocardium from sudden death subjects with alcoholic cardiomyopathy showed diminished redox enzyme activity and higher activity of the enzyme utilizing alcohol (ADG and catalase). The findings suggest that changes in the enzyme activity in the myocardium are of various type and depend on previous cardiac abnormalities.     

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 trivalent iron on denervated skeletal muscles

The activity of succinic dehydrogenase, myosin ATPase, as well as lactic dehydrogenase (LDG) spectrum and cross-section area of different type of muscle fibers have been studied for 3 weeks after denervation (control) and after denervation and intraperitoneal injection of 10(-6) M FeCl3. Intraperitoneal injection of FeCl3 prevented the development of denervation phenomena (increase in cross-section area of muscle fibers, changes in LDG spectrum).