Fluorescence-determined kinetics of plasma high oxidability in diabetic patients.

The peroxidative potential of whole plasma was studied in thirteen control subjects and twenty-three diabetic patients divided into two groups on the basis of their metabolic control, defined as good (n = 12) or poor (n = 11) according to the fasting blood glucose, glycated hemoglobin and fructosamine levels. The amounts of thiobarbituric reactive substances (TBARS) were determined before and after an exhaustive peroxidation induced by incubation with cupric sulfate; the kinetics of Cu-dependent plasma peroxidation, determined by the time course of endogenous fluorescence emission at 430 nm, were also evaluated. Our data indicate that in diabetic patients, and particularly in those with a long-lasting poor metabolic control, a significant increase in plasma susceptibility to peroxidative stress is evident only when we consider the lag-time of fluorescence emission in the course of Cu-induced plasma peroxidation. A good inverse correlation was observed between the lag-time and the blood glucose concentration, the glycated hemoglobin and the fructosamine blood levels. Furthermore a multivariate analysis, performed by Principal Component Analysis, strongly supports the relation between the extent and duration of the diabetic pathology, and the decrease in the lag-time of oxidation.

[Effects of isosorbide-5-mononitrate on exercise capacity, prostacyclin synthesis, the renin-aldosterone axis and catecholamines in patients with cardiac insufficiency]. / Effetti dell'isosorbide-5-mononitrato sulla capacità di esercizio, sulla sintesi di prostaciclina, sull'asse renina-aldosterone e sulle catecholamine in pazienti affetti da insufficienza cardiaca.

Isosorbide-5-mononitrate (IS-5-MN) is an active metabolite of isosorbide dinitrate with a longer plasma half life. Aim of the study was the evaluation of the effects of 40 mg/day of IS-5-MN on exercise capacity in patients with heart failure NYHA class II. After 1 week of wash-out, 10 patients with heart failure NYHA Class II, assumed 20 mg bid for 3 weeks. Bicycle ergometer tests were performed before (A), at the end of therapy (B), and 1 week later (C); in phase B the stress test was performed after 6 hours from the last assumption of IS-5-MN. We measured 24 hour urinary 6K-PGF1 alpha, the stable metabolite of prostacyclin, basal plasma renin activity (PRA) and plasma aldosterone, exercise-release of epinephrine and norepinephrine at the end of each phase of the study. The treatment with IS-5-MN improved the exercise capacity sigma (Watt.min), A less than (B = C), (p less than 0.01), while delta of heart rate (HR) during exercise (basal HR - maximal exercise HR)/(Watt.min), decreased, A greater than (B = C), (p less than 0.008). Basal BP and HR did not change. This fact seems consistent with the hypothesis of a combined effect of nitrates on both the venular and the arteriolar districts. Basal PRA and aldosterone, and catecholamine release during exercise after IS-5-MN did not change, while only norepinephrine increased 1 week after the end of the therapy, (A = B) less than C, (p less than 0.05): 24 hour urinary 6-K-PGF1 alpha increased after IS-5-MN A less than (B = C), (p less than 0.05). The results indicate that medium-term IS-5-MN treatment increases exercise capacity in patients with heart failure NYHA class II and that the effect lasts for 1 week after nitrate withdrawal at least. Prostacyclin is probably involved in medium-term clinical effect of IS-5-MN.