The effect of gamma irradiation on the structure and enzymatic activity of the nuclear membrane of the liver in pregnant rats and their embryos]

Morphological and biochemical investigations of pregnant rats and embryo liver cell nuclei after in vivo irradiation in the doses of 1 and 2 Gr revealed their high radiosensitivity at all stages of gestation and embryonal development. At damaging effect of radiation, we managed to observe sharp accumulation of products of lipid peroxide oxidation and suppression of the activities of such enzymes as cytochrome-c-oxidase, NAD.N-cytochrome-c-reductase, ATPase and RNAase in liver nuclei of pregnant rats and embryos. The changes of such a kind are shown to intensify with the increasing of irradiation doses. The most profound inhibition of the activities of these enzymes in liver nuclei of embryos irradiated in utero was observed during the period of organogenesis (the 13th day of the development) and in fetal period of embryogenesis (the 17th day of the development), as well as at the 13th and 17th day of gestation. The morphological data also demonstrate the high level of cell nucleus sensitivity to the action of radiation during gestation and embryogenesis.     

The enzymes of fructose metabolism in the liver of chick embryos

The activity of fructose cycle enzymes remains practically constant in chick embryonic liver during ontogenesis. Change in ratio of aldolase A to B activities was detected. It is suggested that fructose enters the cycle via the sorbitol pathway in which aldose reductase and sorbitol dehydrogenase are involved.     

Delayed effects of protein deficiency in nutrition of the pregnant rats on development of the enzymatic system in digestive and nondigestive organs of offspring

It has been found for the first time that protein deficit in female's nutrition during prenatal development of the offspring is accompanied by considerable changes in the activity of intestinal digestive enzymes and of the same hydrolases in the colon, liver and kidneys both in early and in late ontogenesis. It seems possible that changes of the small intestine enzyme functions and hydrolytic functions of other digestive and non-digestive organs in result of an unfavorable early "metabolic/nutritional programming" may be crucial in disorders of metabolic processes leading to development of diseases of risk in adult life.     

The effect of a low dose of ionizing radiation and of gangliosides on the adenylate cyclase activity of the chicken thymus and thyroid in ontogeny

Adenylate cyclase (AC) activity was studied in thymus and thyroid gland of intact chick embryos and those irradiated with a dose of 0.029 Gy prior to incubation, and newly hatched chicks in the presence of total ganglioside fractions extracted from the same organs. Gangliosides were shown to increase the enzyme activity of thymocytes and thyrocytes during the postnatal development. It is suggested that small radiation doses potentiate the stimulatory effect of ganglioside fractions on AC.     

Aspartate- and alanine-aminotransferase in early development of keta

We studied the activities of the marker enzymes of physiological state and adaptive reactions, aspartate and alanine aminotransferases, in early development of the keta Oncorhynchus keta. Aspartate aminotransferase with pH optima 6.8, 7.0, 7.6, and 8.0 and alanine aminotransferase with pH optima 7.0, 7.4, 7.6, 7.8, 8.0, and 8.2 were found in the eggs, larvae, and fry. The succession of enzymes with different pH takes place during ontogenesis, as well as stage specific changes in their activity. The maximum enzymatic activity was recorded in the larvae during their rise for "afloat." A correlation was established between the dynamics of enzymatic activity and soluble nitrogen and amine nitrogen contents.     

Ornithine decarboxylase activity in rat tissues in the late periods after irradiation

Ornithine decarboxylase activity in some rat tissues was shown to grow at remote times after gamma irradiation (60Co) with nonlethal doses. The authors suggest that ornithine decarboxylase activity should be used as a biochemical marker of remote effects of ionizing radiation.     

Peanut agglutinin. I. A new tool for studying T lymphocyte subpopulations.

Fluorescein-coupled peanut agglutinin (PNA) has been used at the single-cell level to study mouse lymphocyte subpopulations. PNA not only binds to most thymocytes, as has already been shown by other authors, but also binds to a small fraction of peripheral lymphocytes that are all T cells (theta+Ig-) or null cells (theta-Ig-). Most PNA-positive thymocytes are sensitive to in vivo corticosteroids and irradiation (450 rads) treatments. Conversely, the positive spleen cells (5% of total spleen lymphocytes) are essentially resistant to corticosteroids and irradiation. Study of PNA binding during ontogenesis shows the occurrence of PNA-positive cells in the fetal liver before thymus constitution and in the very beginning of embryonic thymus and spleen development. These data indicate that PNA is a marker of early T cell subpopulations but that there are probably several distinct subsets of PNA-positive T cells.     

On the mechanism of a radiation-induced change in enzymic differentiation during development

In experiments on glucose-6-phosphatase and tyrosine aminotransferase it was shown that radiation induces changes in enzymic differentiation in perinatal rat liver. A study was made of the probable reasons for the observed changes. It was shown that the macromolecular system of the protein enzyme synthesis was not damaged by the radiation doses used. The observed decrease in glucose-6-phosphatase activity during late embryogenesis, after pre-irradiation at early organogenesis, is eliminated by administration of exogenous thyroxine. A radiation-induced rise in the tyrosine aminotransferase activity during the perinatal period correlated with the cyclic AMP system status. It is proposed that modification of enzymic differentiation after irradiation results from the change in the amount of inductors.     

Effect of gamma irradiation on brain enkephalin hydrolase activity in the rat

A study was made of the effect of different radiation doses on the brain enzymes degrading enkephalins. Enkephalin aminopeptidase activity decreased during the first 60 min following irradiation with a dose of 774 X 10(-4) C/kg and increased after a dose of 3096 X X 10(-4) C/kg; enkephalinase A exhibited opposite changes. 48 hr after irradiation, enkephalin aminopeptidase activity exceeded the normal level, and no significant changes occurred in encephaliase A activity irrespective of the radiation dose.     

Radiation disorder of enzyme synthesis in the perinatal period of ontogeny

A change of enzymatic differentiation in the rat liver during the perinatal developmental period after gamma-irradiation on the 7-9th and 19th days of embryogenesis in doses 0.5, 2 and 6 Gr has been shown on the example of glucose-6-phosphatase (G-6-P-ase) and tyrosine aminotransferase (TAT). The protein-synthesizing machinery was not damaged at these doses. The radiation inhibition of G-6-P-ase synthesis was relieved by the injection of thyroxine. A dependence was shown between the radiation increase of TAT activity and changes in cAMP system (increase of cAMP level, decrease of phosphodiesterase activity, intensification of response of adenylate cyclase complex to biogenic amines). A suggestion is put forward that the radiation damage of the enzymes under study is mediated by a change in the number of hormonal inductors.     

The Sensitivity of Resting Eggs of the Cladoceran <Emphasis Type="Italic">Moina macrocopa</Emphasis> to the Effect of Ionizing Radiation during the Reactivation of the Eggs

We investigated the sensitivity of resting eggs of the cladoceran Moina macrocopa to the effect of ionizing radiation during the reactivation of the eggs. The study showed that the resting eggs during reactivation are more vulnerable to irradiation than the resting eggs in a stage of deep dormancy. The decrease in the efficiency of egg reactivation was observed at high doses, the growth rate of juveniles, fecundity, and the number of produced clutches by females strongly decreased when resting eggs at the reactivation stage absorbed doses of 64 Gy and higher.     

Role of the hypothalamus and pituitary gland in the development of pancreatic islet sensitivity to glucose in fetal rats

Differences in the pattern of the development of three enzymes of the plasma membrane have been established. The activity of Na, K-ATPase progressively increases, that of adenylate cyclase decreases, whereas the activity of 5-nucleotidase undergoes only slight changes during embryogenesis. Differences between these enzymes were also found with respect to the development of their sensitivity to the regulatory effects of catecholamines. Adrenaline reactivity of adenylate cyclase may be detected already in embryogenesis; it is lower than that in definite muscle tissue increasing during further ontogenesis. Catecholamine reactivity was not found in Na, K-ATPase and 5-nucleotidase up to the 17th day of incubation of chick embryos. The effect of adrenalin was observed at later stages of ontogenesis, it may be initiated by exogeneous cAMP and protein kinase. At postembryonic stages, similarity in the behavior of these enzymes was found with respect to the presence and pattern of their reaction to adrenalin (stimulation), as well as with respect to temporal dynamics of the effect. The data obtained indicate the existence of close connections between these enzymes, which are realized in the sequence adrenoreceptor-adenylate cyclase-cAMP-protein kinase-effector proteins.     

Studies of pyrimidine metabolism during chick development: two enzymes involved in UMP breakdown

The pattern of uridylate phosphatase and uridine phosphorylase has been studied in the liver, brain, heart and thigh muscles of the chick during development. The study of enzymes involved in pyrimidine metabolism confirms that differences in utilisation of the metabolic pathways exist during ontogenesis. In the liver, starting from the 12th day, an active metabolic pathway, leading to UMP via cytosine should be added to the catabolic ones. In the brain, the second period of embryogenesis should be characterized by a lower utilisation of the catabolic pathways and by an increase of the anabolic ones. In the heart, pyrimidine metabolism during development regards especially UMP. In skeletal muscle, pyrimidine metabolism shows low activity.     

Aspartate and Alanine Aminotransferases in Early Development of the Keta

We studied the activities of the marker enzymes of physiological state and adaptive reactions, aspartate and alanine aminotransferases, in early development of the keta Oncorhynchus keta. Aspartate aminotransferase with pH optima 6.8, 7.0, 7.6, and 8.0 and alanine aminotransferase with pH optima 7.0, 7.4, 7.6, 7.8, 8.0, and 8.2 were found in the eggs, larvae, and fry. The succession of enzymes with different pH takes place during ontogenesis, as well as stage specific changes in their activity. The maximum enzymatic activity was recorded in the larvae during their rise for afloat. A correlation was established between the dynamics of enzymatic activity and soluble nitrogen and amine nitrogen contents.     

The effect of a low dose of ionizing radiation on the activity of cAMP-dependent phosphodiesterase and protein kinase of chicken thymus in ontogenesis

Dynamics of changes in activities of cAMP-dependent enzymes, phosphodiesterase and protein kinase, were studied in the thymus of intact and irradiated, prior to incubation, (0.05 Gy) chicken embryos and chicks. The changes observed were wave-like. In determining phosphodiesterase activity of irradiated chicken thymocytes during ontogenesis the values were obtained that correlated with the cAMP level and adenylate cyclase activity. It was also shown that the increase in the rate of cAMP-dependent phosphorylation under the effect of low-level radiation corresponded to the cyclic nucleotide content of a cell at different development stages.     

Studies on enzymes of nitrogen metabolism, and nitrogen end products in the developing chick (Gallus domesticus) embryo.

1. A total of 450 fertilized eggs were used to study the concentrations of uric acid, urea and ammonia in allantoic and amniotic fluids, and some enzymes of nitrogen metabolism in the liver and kidney during the development of the chick embryo from the 5th to 21st day of incubation. 2. Concentrations of the compounds studied were higher in allantoic fluid. The molar concentration of allantoic uric acid increased steadily with time. The pattern of urea and ammonia in both allantoic and amniotic fluids were the same. 3. Arginase (E.C.3.5.3.1) activity in both embryonic kidney and definitive kidney was higher than that in the liver. The specific activity of arginase (mumole urea formed/hr per g wet wt kidney) dropped during development. 4. Little arginine synthetase activity (argininosuccinate synthetase, E.C.6.3.4.5; and argininosuccinate lyase, E.C.4.3.2.1) was found in kidney, but none in the liver. 5. The complete urea cycle function was absent in both the liver and the kidney of the chick embryo.     

Insulin binding by receptors of the plasma membranes of the liver in hens in ontogenesis

Specific binding of 125I-insulin to the liver plasma membranes was studied in the chick embryos from the 10th day of incubation on, in chickens and adult fowl. The level of binding was the same in all cases although the insulin concentration of blood increases during ontogenesis, the number of receptors and their affinity to the hormone remaining constant. The data on insulin-receptor interactions in the liver have been compared with the earlier results of the authors obtained on the chick skeletal muscle and erythrocytes.     

Studies on the mechanism of action of ionizing radiations. VII. Cellular respiration,cell division,and ionizing radiations

On x-irradiation of the eggs and sperm of Arbacia punctulata there was inhibition of respiration with relatively large doses, whereas there was an increase with small doses. The dose required to produce an increase of respiration depended on the degree of sensitivity of the cell to the effect of ionizing radiation. Sperm cells were more sensitive; then came fertilized eggs; unfertilized eggs were the least sensitive. The inhibiting effect of x-rays on cell division was observed even on irradiation with x-ray doses which produced an increase of respiration. These results are compared to similar effects produced by thiol reagents and are attributed to oxidation of the thiol compounds in the cell.     

Genome mutation yield in the cells of intact and regenerating liver of normal rats and following gamma irradiation

A comparative study was made of spontaneous and induced polyploidy in cells of resting and regenerating rat liver. Polyploidy was shown to play a major role in the ontogenesis and during regeneration after partial hepatectomy. An essential difference was revealed in the radiation response of cells of intact and regenerating liver with respect to the yield of polyploid cells. This distinction was referred to different effectiveness of the processes of repair and fixation of radiation damages in the actively proliferating and resting cells.     

Hepatic radiation injury in the rat.

The whole livers of rats were exposed intraoperatively to graded doses (0 to 75 Gy) of 137Cs gamma radiation. At various times (0 to 155 days) after liver irradiation, minimally invasive, nondestructive tests (rose bengal retention and plasma alkaline phosphatase, glutamic-oxaloacetic acid transaminase, glutamic-pyruvic transaminase) were performed on at least half the surviving animals in each dose group to assess developing liver injury. Liver histology was done on animals sacrificed 96 to 100 days after irradiation. Radiation damage to the stomach killed approximately 50% of the animals 30 to 60 days after exposure to doses of 25 Gy or higher. These deaths were significantly reduced when care was taken to shield the stomach during irradiation. Stomach injury did not, however, appreciably affect liver function as measured by rose bengal retention. Whole-liver irradiation to 15 Gy resulted in reduced liver size and minimal histological changes, but did not result in increased rose bengal retention or plasma alkaline phosphatase concentration. The next highest dose group studied (25 Gy) showed significant histological abnormalities and liver injury as measured by increased rose bengal retention and liver enzymes. The latent period for development of hepatic injury, as measured by increased rose bengal retention, was 35 to 42 days and was relatively invariant over the 25- to 75-Gy dose range. Hepatic vein lesions and cellular necrosis were the most prominent histological lesions observed in 25-Gy-irradiated liver.