Glutamate uptake inhibition by oxygen free radicals in rat cortical astrocytes.

Formation of reactive oxygen species and disfunction of the excitatory amino acid (EAA) system are thought to be key events in the development of neuronal injury in several acute and long-term neurodegenerative diseases. Recent evidence suggests that the two phenomena may be interdependent. The present study is aimed at exploring possible molecular mechanisms underlying oxygen radical-EAA interaction. Exposure of cortical astrocytic cultures to either xanthine + xanthine oxidase (X/XO), a free radical-generating system, or hydrogen peroxide (H2O2) results in a marked decrease of high-affinity glutamate transport. Within 10 min of X/XO application, uptake falls to approximately 60% of its control value. In parallel no detectable release of lactate dehydrogenase occurs. X/XO effect is abolished in the presence of a mixture of scavenger enzymes (superoxide dismutase+catalase) or by the disulfide-reducing agents glutathione and dithiothreitol (DTT), but not by lipophilic antioxidants or ascorbate. The time course of inhibition shows an almost linear decline of glutamate transport during cell exposure to free radicals, while upon their inactivation the decline stops but established inhibition persists for at least 1 hr. In this situation, application of DTT significantly restores transport function. These data suggest that free radicals inhibit glutamate uptake primarily by long-lasting oxidation of protein sulfhydryl (SH) groups. Chemical modifiers of free SH groups, such as p-chloromercuribenzoate and N-ethylmaleimide, also induce uptake inhibition. Na+/K+ ATPase is a known target of oxygen radicals and may be involved in glutamate uptake inhibition. Indeed, ouabain, a blocker of the pump, reduces uptake in astrocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

[Physiological and psychopathological aspects of eating behavior]. / Aspetti fisiologici e psicopatologici della condotta alimentare.

Eating behaviour variations are often observed in medical practice. Sometimes they are physiological manifestations, rarely they are paraphysiological, many times they amount to pathological behaviour. Their heterogeneity could account for treatment problems met by the family doctor. Our study was aimed to increase the family doctor's attention to the eating behaviour of their patients. Greater awareness in family doctors of problems in their patients' eating behaviour may be apt to lead to an improvement in dietary habits and consequently to greater psychologic and physical wellbeing of the patients.

[Reduction modality of a dietary questionnaire]. / Modalità di riduzione di un questionario alimentare.

The data relative to the average daily intake of 7 nutrients and total energy obtained through the answers to a dietary questionnaire, consisting of 152 items and administered to 200 patients (admitted for acute pathologies) has been analysed. The aim has been to elaborate a questionnaire consisting of a more limited number of items but maintaining a great part of the informative contents from the original questionnaire. For this aim, a multiple regression model with a selection procedure for independent variables, of the stepwise type, has been used, where the dependent variable is the daily average intake of the nutrient and the independent variables are the consumption of each food included in the complete questionnaire (QC). By combining the results of the model with the 7 nutrients and total energy, 3 reduced questionnaires have been produced (QR): the first two are based on the sole criteria of the inter-individual variance of the intake of the nutrient, explained by the consumption of the foods included in the QR, the third by adding the foods that offer an adequate contribution in order to explain the supply of the nutrient under examination. The application potentials of the 3 QRs have been analysed both by evaluating the inter-class correlation coefficient, deduced by an concordance/discordance matrix relative to the quintilis values of the nutrient deduced by the QC and by each QR, and by simulating their use in a case-control study; for this aim, the attenuation of the odds ratio trend and the increase of the sample dimension has been calculated following the use of a QR instead of a complete one.(ABSTRACT TRUNCATED AT 250 WORDS)

[Electrocardiogram changes in the rat by coenzyme A action]. / Modificazioni dell'elettrocardiogramma del ratto per azione del coenzima A.

The authors, having in a previous series of experiments observed that coenzyme A, administered intravenously in doses from 200 to 500 U.L., causes an immediate and transient decrease of the sinus rate, wanted to study to which part of the complex molecule of coenzyme A such effect is due. That's why they studied the action, intravenously, of pantothenic acid (200-400 mg/Kg), of cysteine (40-80 mg/Kg), of pantethein (40-100 mg/Kg) and of adenosine (4-10 mg/Kg). The results of the experiments demonstrate that the former bradycardia is due to adenosine, whereas the other substances have not this effect.

[Electrocardiographic changes in the rat induced by digitalis glucosides]. / Modificazioni dell'elettrocardiogramma del ratto per azione di glucosidi digitalici.

Electrocardiographic changes induced by desacetil-lanatoside C and digitoxin, administered intravenously, have been studied in 25 anesthetized rats. No differences were observed between the actions of the two glucosides. Their negative chronotropic action can be effected with two mechanisms: one indirect, through vagal reflex, therefore immediate and, in general, brief; one direct, for direct action on the heart, which is gradual and long lasting. Their action on the a-v conduction is recorded by a rise in the duration of the P-Q tract, or, for higher doses, by blocking fenomena, which are brief and completely reversible. Signs of subendocardial damage are often observed, these too brief. The appearance of extrasystoles is rare.

[Electrocardiographic changes in the rat induced by high doses of the coenzymatic forms of several vitamins of the B group]. / Modificazioni dell'elettrocardiogramma del ratto per azione di alte dosi delle forme coenzimatiche di alcune vitamine del gruppo B.

No modification, neither immediate nor late, was observed after the intravenous injection of high doses of the coenzymatic forms of thiamine and pyridoxine. On the contrary, after the injection of high doses of the coenzyme A, a sudden, conspicuous and brief (20-25") diminution of heart rate was observed. Such a phenomenon was much more marked and longer if, before the coenzyme A, a digitalic compound (desacetil-lanatoside C or digitoxin) was administered.

Panthenol and glucocorticoids.

Urinary metabolites of glucocorticoids have been measured in man before and after administration of panthenol in high doses. The quantitative assay was performed according to the technique of Porter and Silber which measures only cortisol and some of its metabolites. In all panthenol treated subjects a significant increase in the urinary excretion of 17-alpha-21-dihydroxy-20-keto steroids has been observed and it appeared to be higher in male ageing between 18 and 25. The results obtained confirm that a statistically significant increase in glucocorticoid production after panthenol administration in high doses is present also in man.

[Experimental electrocardiography research. A study in the rat of the cardiovascular effects of verapamil]. / Ricerche di elettrocardiografia sperimentale. Studio nel ratto degli effetti cardiovascolari del verapamil.

Electrocardiographic changes induced by Verapamil, drug inducing inhibition of transmembrane movement of calcium into cardiac cells and mobilization of intracellular Ca++, have been studied in 10 anesthetized rats. Authors observed that Verapamil has: 1) negative chronotropic action on SA node; sometimes appears a superior nodal rhythm; 2) inconstantly, negative dromotropic action with prolonged atrioventricular conduction and "period of Luciani-Wenckebach'; 3) effective antiarrhythmic action; 4) no protective action towards peripheric vascular epinephrine effects; 5) remarkable negative inotropic action, whose Authors consider indirect signs the electrocardiographic changes, which indicate severe coronary failure, and the death of 6 rats by acute pulmonary edema.

[Experimental electrocardiographic research. Study in the rat of the cardiovascular effects of labetalol]. / Ricerche di elettrocardiografia sperimentale. Studio nel ratto degli effetti cardiovascolari del labetalolo.

Electrocardiographic changes induced by Labetalol, a drug blocking alpha- and beta-adrenergic receptors, have been studied in 10 anesthetized rats. Authors observed that Labetalol has: 1) slightly negative chronotropic action; 2)slightly negative dromotropic action on both atrio-ventricular and intraventricular conduction; 3) effective antiarrhythmic and alpha-blocking action and, inconstantly, 4) the so-called "intrinsic sympathicomimetic action" (I.S.A.), typical of several beta-blocking drugs.

[Research in experimental electrocardiography. I: action of DCA-ajmaline on the electrocardiogram of the rat]. / Ricerche di elettrocardiografia sperimentale. Nota I: azione della DCA-ajmalina sull'elettrocardiogramma del ratto.

In the course of their experiments, the Authors did not observe any modifications in the rat electrocardiogram, induced by a 2,5 mg DCA-ajmaline intravenous injection, nor, in particular, any negative bathmotropic action due to it.

[Therapeutic action of vitamin C on cholesterol metabolism]. / Azione terapeutica della vitamina C sul metabolismo del coleste rolo.

As a part of the research work on the role played by Vitamin C on lipidic metabolism, the effects on man were considered that result from the administration of high vitamin C doses, chiefly with reference to the serum levels of colesterol, of total lipids and of triglycerides. Our research was conducted on male subjects of 65-90 years, who were administered 3 g/day of vitamin C for three weeks. Our findings show that the administration of high vitamin C doses causes a statistically significant decrease in colesterol, in total lipids and in triglycerides, in all the subjects under consideration. This takes place not only when colesterol, total lipids and triglycerides present normal serum levels, but also when such levels show an increase. Conversely, vitamin C significantly increases, with treatment, in all subjects treated, both in plasma and in leukocytes.

[Research in experimental electrocardiography. II: effect of a beta-blockader (pindolol) on the electrocardiogram of the rat]. / Ricerche di elettrocardiografia sperimentale. Nota II: Effetti di un beta-bloccante (il pindololo) sull'elettrocardiogramma del ratto.

From the Authors' observations during this research, there emerges the fact that pindololo does not seem deprived of that cardiodepressive action, which is typical of all beta-blocking drugs.