Browsing by Author "Bicho, M."
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- Influence of oxidative stress produced by nitrite in the activity of methaemoglobin reductase in two different species of fishPublication . Aníbal, J.; Bicho, M.Nitrite induces the oxidation of the haemoglobin forming methaemoglobin, which is nonfunctional. To oppose this formation fishes have an enzyme that reverses the process called methaemoglobin reductase. In vitro activity of the methaemoglobin reductase was determined, in the presence and absence of nitrite in two marine fishes (toadfish, Halobatrachus didactylus and gilt head sea breams Sparus aurata). The KM and Vmax were determined through the Eisenthal and Cornish-Bowden Plot. The basis for this study is that the methaemoglobin reductase system has very active ferricyanide reductase activity. Halobatrachus didactylus showed a significant decrease in its values of methaemoglobin reductase activity with the increase in nitrite concentration (38.9; l6.3; 14.5: l4.0 and 12.3 mmol NAD+/min/gHB respectively to 0; 1; 3; 6 and 9 mM N02). In Sparus aurata, the nitrite didn't induced significant variations in the methaemoglobin reductase activity (27.8; 27.1; 25.3; 22.3 and 18.7 mmol NAD+/min/gHB respectively to 0; 1; 3; 6 and 9 mM N02). This results probably indicate fish to have other paths opposing to the formation of methaemoglobin, rather than the enzymatic system of the methaemoglobin reductase. At the moment the meaning of this of this different behaviour is not known.
- Polimorfismo genético da haptoglobina e grau de gravidade da hipertensão arterial essencialPublication . Monteiro, C.; Lança, H.; Joaquim, N.; Lamy, I.; Aníbal, J.; Coucelo, Josefina; Azevedo, J.; Bicho, M.É conhecida a associação do polimorfismo genético da haptoglobina(Hp)quer com a sensibilidade ao sódio da pressão arterial quer com a gravidade hipertensão arterial (HTA).
- Polimorfismo genético da haptoglobina e grau de gravidade da hipertensão arterial essencialPublication . Monteiro, C.; Lança, H.; Joaquim, N.; Lamy, I.; Aníbal, J.; Coucelo, Josefina; Azevedo, J.; Bicho, M.A susceptibilidade genética para a hipertensão arterial envolve processos nos diferentes passos da sua história natural que podem estar activos em indivíduos e/ou famílias. Nesta susceptibilidade consideram-se o desenvolvimento da doença o seu curso clínico em termos de gravidade e complicações e ainda a variação da resposta terapêutica.
- The activity of methaemoglobin reductase in toadfish (Halobatrachus didactylus) and gilt head sea bream (Sparus aurata)Publication . Aníbal, J.; Bicho, M.The erythrocytes intracellular oxidative stress oxidizes the haemoglobin forming methaemoglobin, which is nonfunctional. To oppose this formation fishes have an enzyme that reverses the process called methaemoglobin reductase. In vitro activity of the methaemoglobin reductase was determined in two marine fishes with different habitats and behaviours (Halobatrachus didactylus and Sparus aurata). The KM and Vmax, were determined through the Eisenthal and Cornish-Bowden Plot. The basis for this study is that the methaemoglobin reductase system has very active ferricyanide reductase activity, using NADH as the electrons donor. Halobatrachus didactylus showed higher values of methaemoglobin reductase activity (38.9 mmol NAD+/min/gHb) than Sparus aurata (27.8 mmol NAD+/min/gHb). The reductase of Halobatrachus didactylus had, for both substrates, higher values of KM (potassium ferricyanide: 0.133 mM, NADH: 0.067 mM) and lower values of Vmax (potassium ferricyanide: 0.097 min-1; NADH: 0.025 min-1), than Sparus aurata (potassium ferricyanide: KM=0.092 mM, Vmax=0.176 min-1, NADH: KM=0.032 mM, Vmax=0.062 min-1). The results indicated that Halobatrachus didactylus’s methaemoglobin reductase had high antioxidant efficiency, although that one of the Sparus aurata had more sensitivity to the presence of low concentrations of methaemoglobin. The meaning of this different behaviour, at the moment can not be envisaged.