Quando indicar marcapasso na TAVI? / When to indicate a pacemaker in TAVI?

O implante por cateter de prótese valvar aórtica (TAVI) constitui um marco na cardiologia moderna, sendo uma alternativa terapêutica fundamental para os pacientes inoperáveis ou com risco intermediário para cirurgia de troca valvar aórtica...

Effect of hypoxanthine, antioxidants and allopurinol on cholinesterase activities in rats.

In the present study, we investigate the in vitro effect of hypoxanthine on acetylcholinesterase and butyrylcholinesterase activities in the hippocampus, striatum, cerebral cortex and serum of 15-, 30- and 60-day-old rats. Furthermore, we also evaluated the influence of antioxidants, namely α-tocopherol (trolox) and ascorbic acid, and allopurinol to investigate the possible participation of free radicals and uric acid in the effects elicited by hypoxanthine on these parameters. Acetylcholinesterase and butyrylcholinesterase activities were determined according to Ellman et al. (Biochem Pharmacol 7:88-95, 1961), with some modifications. Hypoxanthine (10.0 µM), when added to the incubation medium, enhanced acetylcholinesterase activity in the hippocampus and striatum of 15- and 30-day-old rats and reduced butyrylcholinesterase activity in the serum of 60-day-old rats. The administration of allopurinol and/or antioxidants partially prevented the alterations caused by hypoxanthine in acetylcholinesterase and butyrylcholinesterase activities in the cerebrum and serum of rats. Data indicate that hypoxanthine alters cholinesterase activities, probably through free radicals and uric acid production since the alterations were prevented by the administration of allopurinol and antioxidants. It is presumed that the cholinesterase system may be associated, at least in part, with the neuronal dysfunction observed in patients affected by Lesch-Nyhan disease. In addition, although extrapolation of findings from animal experiments to humans is difficult, it is conceivable that these vitamins and allopurinol might serve as an adjuvant therapy to avoid progression of brain damage in patients affected by this disease.

In vitro stimulation of oxidative stress by hypoxanthine in blood of rats: prevention by vitamins e plus C and allopurinol.

We herein investigated the in vitro effect of hypoxanthine on the activities of antioxidant enzymes such as catalase (CAT), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) in erythrocytes, as well as on thiobarbituric acid-reactive substances (TBA-RS), in the plasma of rats. Results showed that hypoxanthine, when added to the incubation medium, enhanced CAT (10.0 µM), GSH-Px and SOD (8.5 µM and 10.0 µM) activities in erythrocytes of 15-day-old rats, reduced CAT activity (10.0 µM) and enhanced GSH-Px activity (10.0 µM) in erythrocytes of 30-day-old rats, reduced CAT activity (10.0 µM) and enhanced GSH-Px activity (8.5 µM and 10.0 µM) in erythrocytes of 60-day-old rats, as compared to controls. In addition, hypoxanthine (10.0 µM) enhanced TBA-RS levels in the plasma of 30- and 60-day old rats. Furthermore, we also tested the influence of allopurinol, trolox, and ascorbic acid on the effects elicited by hypoxanthine on the antioxidant enzymes and TBA-RS. Allopurinol and/or administration of antioxidants prevented most alterations caused by hypoxanthine in the oxidative stress parameters evaluated. Findings suggest that hypoxanthine alters antioxidant defenses and induces lipid peroxidation in the blood of rats; however, in the presence of allopurinol and antioxidants, some of these alterations in oxidative stress caused are prevented. Data indicate that, in humans, antioxidant administration might serve as a potential adjuvant therapy for ameliorating the damage caused by hypoxanthine.