Effect of whole-body gamma irradiation on lipid peroxidation in rat tissues.

In this work, we studied the influence of whole-body gamma irradiation (800 rads) upon malonaldehyde (MDA) content in plasma, erythrocyte, brain, heart, lung, kidney, spleen, liver, thymus and bone marrow. MDA levels were increased in all studied samples, except lung; the highest increases were observed in the most radiosensitive organs (bone marrow, thymus, spleen) and not in those continuously exposed to high concentrations of molecular oxygen (lungs, erythrocytes). Comparison of the variations of MDA levels in plasma, kidneys and spleen to those in the other tissues lead to the hypothesis that MDA is released from tissues in plasma and trapped from plasma in kidney and spleen. The variations in plasma and erythrocyte were found not to be related to each other.

Influence of whole-body gamma-irradiation upon rat erythrocyte: lipid peroxidation and osmotic fragility.

The effects of whole-body gamma-irradiation of rats (8 Gy) on erythrocyte enzymes and biochemical components involved in lipid peroxidation were studied. Decreased superoxide dismutase and glutathione reductase activities, and lowered concentrations of reduced glutathione, were found to be the main factors responsible for the observed increase in lipid peroxidation in the erythrocytes of irradiated rats. This increased lipid peroxidation did not result in a greater tendency to hemolysis in hypotonic media; on the contrary, the mean osmotic fragility was decreased at days D + 1 and D + 3 after irradiation. The behavior of the erythrocyte populations towards hemolysis in hypotonic media appeared to be most homogeneous at days D + 4 and D + 8 after irradiation, which correspond to maxima of malonic dialdehyde concentrations in erythrocytes. Such a synchrony of variations suggests that crosslinking of primary amino groups of proteins or phospholipids by malonic dialdehyde might produce a rigidification in erythrocyte membranes, possibly leading to a more homogeneous behavior of the erythrocyte populations towards hemolysis in hypotonic media.

Influence of whole-body gamma irradiation upon arachidonic acid metabolism in rat platelets.

The effects of whole-body gamma irradiation (8.4 Gy) were studied on arachidonic acid (AA) metabolism in rats' blood platelets, from day D + 1 to day D + 10 after irradiation. AA conversion into thromboxane B2 (TxB2) increased at D + 1 and then gradually decreased to very low values from D + 7 to D + 10. This decrease in the conversion of exogenous AA into TxB2 was due to a lower AA incorporation into platelets and not to a decrease of cyclooxygenase and thromboxane-synthetase activities. AA incorporation into membrane phospholipids of blood platelets was much more decreased than AA incorporation into whole platelets; moreover, the lipid composition of the platelet membranes was markedly modified after irradiation, which must have resulted in structural and functional changes in these membranes; from these effects of whole-body gamma irradiation on platelets, the latter's membranes appeared as a major site of in vivo radiation damage in these cells.

Effects of whole-body gamma irradiation on oxygen transport by rat erythrocytes.

In this work, we studied the influence of whole-body gamma irradiation (8 Gy) upon oxygen transport by erythrocytes, through the erythrocyte count and related parameters, and through the factors affecting the oxygen affinity of hemoglobin. The oxygen affinity of hemoglobin is increased from day D + 5 after irradiation, and a severe erythropenia develops from day D + 8. These modifications probably result in tissue hypoxia via diminished oxygen transport from lungs to tissues, and decreased oxygen release from oxyhemoglobin in tissues.

[Effect of gamma irradiation on the production and degradation system of the second hormonal messenger (author's transl)]. / Effets de l'irradiation gamma sur les systèmes de production et de dégradation du 2e messager hormonal

Gamma irradiation of rat liver plasma membranes leads to a decrease of the adenylcyclase activities stimulated by glucagon and fluoride. The observed inhibition is more important for the activity stimulated with glucagon. The 5'-nucleotisade activity is not changed by irradiation. When the phosphodiesterase system is submitted to gamma irradiation, the radiosensibility of enzymatic complex is more important.

[Variation of plasmatic adenosine 3'', 5-cyclic monophosphate in irradiated-enterectomised dogs (author's transl)]. / Variations du taux d'adénosine 3',5-monophosphate cyclique (ampc) chez des chienx irradiés entérectomisés

In the irradiated dog at different doses 250-400 R., a level plasma AMPc rise has been shown since the fourth hour with a maximum at 24 hours, returning to normal values about the thirtieth day. In irradiated at 250-300 R and secondarily enterectomised animals, nucleotide level rises 24 hours later, however this phenomenon is less intensive and later irradiated at 350 and 400 R.

Studies of microsomal glucose-6-phosphatase on liver of irradiated rats.

The activity of microsomal glucose-6-phosphatase (EC 3.1.3.9) on male rat liver was measured 1-9 days after whole-body gamma-irradiation. A marked fall of activity, expressed per whole liver, was observed reaching a minimum on the 4th day following irradiation. The enzyme activity is partially and momentarily restored (on day 7), before a new decrease occurred. Furthermore, when the results are expressed per milligram of microsomal proteins, there was no change. Cysteamine, when injected in vivo, kept up the glucose-6-phosphatase of whole liver. On day 4, a histochemical demonstration of the enzyme in liver cells is in accordance with enzyme measures. These observations suggested that the enzyme quantity was altered during the acute radiation syndrome in the rat.

[Chronic neurological syndrome resulting from intoxication with metallic uranium (author's transl)]. / Intoxication par l'uranium métallique. Manifestations neurologiques chroniques.

In 1972, a male patient, then 44-year-old, developed foot cramps and leg pain together with increasing gait disorders and a tendency to fall backwards. In 1976, an extrapyramidal syndrome with ataxia, nystagmus and peripheral neuropathy was discovered on neurological examination. The symptoms persisted and remained of obscure origin until 1979, when a detailed aetiological enquiry disclosed that during at least the first three years of his illness the patient had had on his desk a bar of metallic uranium which he frequently handled. Stool analysis showed significant uranium levels. In the absence of any other cause, it would appear that the neurological syndrome was due to intoxication with uranium. Although this had not been previously described in man, there are occasional reports of uranium toxicity in laboratory animals.

[Changes during the six years after an experimental radioactive contamination in man]. / Evolution sur six ans d'une contamination radioactive humaine expérimentale

One of us has inhaled, in very well defined conditions, a mixture of radioactive substances originating from the heart of an electronuclear reactor and able to lead to a corresponding irradiation of the magnitude of the maximum permissible quarterly dose for the lungs. This internal contamination has been monitored for six years.