Radiation chemistry of ices of planetological interest at low temperature.

We present the results of recent experiments on some physico-chemical effects induced by fast ion colliding with solids of relevance for the physics of planetary objects. The production of molecular solids, polymer-like materials and amorphous carbon by irradiation of frozen hydrocarbons and pentacene is discussed. We also report on a set of experimental results obtained irradiating methanol and water-methanol mixtures. Because of bombardment different species form. The techniques used for the analysis are "in situ" infrared (IR) and Raman spectroscopy. The experimental results are finally discussed in the light of their relevance for planetary physics.

Free radical scavenger depletion in post-ischemic reperfusion brain damage.

In the present study the influence of pretreatment with various GSH depletors such as buthionine sulfoximine (BSO) and diethylmaleate (DEM) was investigated in rats following cerebral post-ischemic reperfusion. Moreover, the effect of diethyldithiocarbamic acid (DDC), inhibitor of endogenous Cu,Zn-SOD, was evaluated. A significant depletion (40% of control value) of GSH levels was observed 24 h after DEM administration; after 48 h the value reached control levels. BSO showed maximal GSH depletion (59%) 24 h after administration and it was constant for almost 48 h. DDC administration caused a marked decrease (60%) of Cu,Zn-SOD activity 4 h after the injection and induced a marked decrease in percentage of survival with respect to control (untreated, ischemic) rats, when administered 4 h before ischemia. BSO and DEM prolonged the survival time of animals when administered 24 h before ischemia. This last paradoxical effect is unclear at present, but it might be due to an influence on glutamate cascade.

Effect of acetyl-L-carnitine on lipid peroxidation and xanthine oxidase activity in rat skeletal muscle.

It has been reported that acetyl-L-carnitine (AcCn) can reduce the degenerative processes in the central nervous system of rats, modify the fluidity of membranes and decrease the accumulation of lipofuscins in neurones. In light of these considerations we have assayed the in vitro effect of acetyl-L-carnitine on spontaneous and induced lipoperoxidation in rat skeletal muscle; in addition, the effect of AcCn on XD/XO ratio was evaluated. The presence of AcCn (10-40 mM) in incubation medium significantly reduced MDA and conjugated diene formation in rat skeletal muscle; moreover, a significant decrease in induced MDA levels was observed when microsomal preparation where incubated in the presence of 10-40 mM AcCn. Since a significant reduction of XO activity was detected in the presence of 10-80 mM AcCn, the reduced lipid peroxidation by AcCn seems to be due to an inhibition of XO activity.

Transglutaminase activity in primary and subcultured rat astroglial cells.

Transglutaminases, calcium-dependent thiol enzymes, may be involved in cellular growth control and differentiation, having an intracellular regulatory role in some post-translational modifications found in various classes of proteins. In order to elucidate the involvement of this class of enzymes in cellular differentiation processes, we have assayed transglutaminase activity in primary and subcultured rat glial cells. Reduced activity was found from 3rd to 5th passage. In the 5th passage the activity was some 50% of that found in the primary cultures and was not restored by addition of 10 microM retinoic acid. The decrease of TGase activity, observed during serial passages, could represent an early metabolic alteration related to cell dedifferentiation and loss of growth control. In fact, the subcultured cells may have undergone a "disarranged" state, as confirmed by a decrease in GFAP-stained cells and glutamine synthetase activity, respectively, immunocytochemical and biochemical markers of astroglial cells.

Lipid peroxidation and antioxidant enzymatic systems in rat retina as a function of age.

In the present study, we have assayed the enzymatic activity of Cu,Zn-SOD, Mn-SOD, GSH-Px, GSH-Red, Cat, and G6PD in rat retina as a function of age. Conjugated diene levels and MDA formation were also determined. The conjugated diene levels in rat retina were found to increase significantly with age, accompanied by a marked decrease in GSH-Px and Cat activities. No age-related change in MDA levels and in GSH-Red and G6PD activity was found, whereas a significant increase in SOD activity was observed between 1 and 4 months. Decreased GSH-Px and Cat activity is related to increased lipid peroxidation with age.

Synthesis of carboxyalkylthio-triazoles and bicyclic derivatives with antiinflammatory and analgesic activity.

3-Carboxyalkylthio derivatives of 5-alkoxyphenyl-1,2,4-triazole were prepared, performing some substitutions both on carboxyalkyl chain, by lengthening it or introducing substituents with increasing molecular weight in alpha- at the carboxy group, and on N-4 atom in the triazole ring, by introducing an amino or methyl group, so that to vary steric conformation along with the lipophilicity of molecules. The corresponding bicyclic thiazolo-triazolone and triazolo-thiazinone derivatives, which represent the rigid models of carboxymethylthio- and carboxyethylthio- open structures, were also obtained. All the compounds show "in vivo" antiinflammatory activity, while only carboxyalkylthio derivatives of 4-amino- and 4-methyltriazole display an appreciable analgesic one. From the relief of some data on substituent present in the synthesized compounds, a structure-activity relationship is also suggested.

Lipid peroxidation in rat cerebral cortex during post-ischemic reperfusion: effect of exogenous antioxidants and Ca(++)-antagonist drugs.

Although the role of oxidant-antioxidant metabolism in total ischemia and reperfusion in the central nervous system and cardiac myocardium have been well studied, less is known about the consequences of partial ischemic episodes. Here we show that reperfusion contributes to free radical formation as judged by conjugated diene formation. Also, antioxidants and Ca++ antagonists were able to reduce free radical formation. These results would suggest that free radical generation following ischemia and reperfusion may result from more than one injury process in cerebral cortex.

Antioxidant enzymatic systems and oxidative stress in erythrocytes with G6PD deficiency: effect of deferoxamine.

In the present study we have assayed the effect of divicine in G6PD-deficient red blood cells in the presence of deferoxamine (iron-chelating drug) and NaN3 (inhibitor of catalase). The effect of divicine has been compared to oxidative stress by H2O2; haemolysis is regarded as an index of cellular toxicity. In addition, we have tested antioxidant enzymatic systems. No significant change in antioxidant enzymatic systems was found in RBCs from subjects with G6PD deficiency when compared to the control group, either in oxidative haemolysis by divicine or by H2O2; a significant decrease in oxidative haemolysis by H2O2 was observed in the presence of deferoxamine, whereas no change was found in oxidative haemolysis by divicine. The replacement of incubation medium by homologous plasma or the supplementation with bovine serum albumin resulted in a marked decrease of percentage of haemolysis by divicine.

Neurotransmitter amino acid levels in rat thalamus and cerebral cortex after cerebellectomy.

Glutamate, aspartate, GABA, glycine and taurine levels have been measured in rat thalamus and in cerebral cortex at different time intervals (3rd, 7th, 15th, 30th day) after cerebellectomy. A decrease in glutamate, aspartate and GABA was detected at the 7th day after cerebellectomy in the thalamus and at the 15th day in the cerebral cortex; at the 30th day after cerebellectomy the levels of these amino acids in the thalamus and in the cerebral cortex were observed to have recovered to control values. No statistically significant difference in glycine and taurine levels in the thalamus and in the cerebral cortex after cerebellectomy could be seen. These results show that the functional recovery process after cerebellar injury is associated with a complex modification of amino acid levels in thalamus and in cerebral cortex.

Antioxidant enzymatic systems in human erythrocytes from subjects with chronic cerebrovascular disease.

In the present study we have assayed antioxidant enzymatic systems in erythrocytes from subjects with chronic cerebrovascular disease to correlate their involvement in red cell deformability. A significant decrease of glutathione peroxidase, reductase, catalase and superoxide dismutase activities has been found in human red blood cells from patients with chronic cerebrovascular disease when compared to the control group. The decrease in antioxidant enzymatic systems found in these patients was accompanied by reduced cellular resistance to hydrogen peroxide. An altered balance between the partially reduced forms of oxygen metabolism and the antioxidant enzymatic systems could play a crucial role in the haemorheological alteration frequently occurring in subjects affected by chronic cerebrovascular disease.

Ornithine decarboxylase and transglutaminase activities in rat placenta during pregnancy.

Ornithine decarboxylase (L-Orbithine carboxylase, E.C. 4.1.1.17) and transglutaminase (R-glutaminylpeptide: amine gamma-glutamyltransferase, E.C. 2.3.2.1.13), enzymes implicated in the regulation of growth processes, were studied in rat placenta during pregnancy; the specific activity of TGase increased from the 15th day until the 21st day of pregnancy while no significant difference of ODC activity was observed; moreover, the ODCase/TGase ratio decreased significantly in rat term placenta.

Superoxide dismutase activity and reduced glutathione content in cataractous lens of patients with glucose-6-phosphate dehydrogenase deficiency.

In the present research we have assayed the glucose-6-phosphate dehydrogenase, superoxide dismutase activities and reduced glutathione content in human cataractous lenses of 83 Sicilian subjects. Five of 45 males were G6PD deficient, whereas eight of 38 females showed a significant reduction in G6PD by 50%. The five males hemizygous for G6PD defect showed undetectable G6PD activity and low GSH levels in their lenses when compared to cataractous patients without erythrocyte G6PD deficiency; on the contrary, the specific activity of lenticular total SOD was found to be significantly increased. The G6PD and SOD activities as well as GSH levels, in the lenses of eight females with intermediate erythrocyte G6PD levels, were not significantly different when compared to females with normal erythrocyte G6PD activity.