No abstract

OBJECTIVE -Recently, much attention has been paid to the possibility that postprandial hyperglycemia may be a cardiovascular risk factor in diabetes. Oxidative stress has been involved in the pathogenesis of diabetic complications, and increased plasma levels of nitrotyrosine, a product of peroxynitrite action, have been found in the plasma of diabetic subjects. The aim of the present study was to evaluate whether postprandial hyperglycemia is accompanied by nitrotyrosine generation and, if so, to explore a possible direct role of hyperglycemia in such a phenomenon. RESEARCH DESIGN AND METHODS-A total of 23 type 2 diabetic patients and 15 matched normal healthy subjects were recruited for this study. Two different tests were performed in diabetic patients: a standard meal preceded by regular insulin (0.15 units/kg body wt) or insulin aspart (0.15 units/kg body wt) to achieve different levels of postprandial hyperglycemia. The meal test was also performed in healthy control subjects. At 0 min and 1, 2, 4, and 6 h after each meal, blood glucose, triglyceride, and nitrotyrosine levels were measured.RESULTS -Fasting nitrotyrosine was significantly increased in diabetic patients and was further increased during both meal tests in diabetic subjects but not normal subjects. As compared with regular insulin, aspart administration significantly reduced the area under the curve of both glycemia (P Ͻ 0.04) and nitrotyrosine (P Ͻ 0.03), whereas that of triglycerides was not significantly affected by the treatment.CONCLUSIONS -This study shows a direct correlation between postprandial hyperglycemia and the production of nitrotyrosine, a marker of oxidative stress, in patients with type 2 diabetes.

OBJECTIVE -Diabetes increases the risk of coronary heart disease (CHD) to a greater extent in women than in men. We investigated whether type 1 diabetic patients with short duration of disease and without complications have an altered oxidative status and whether there are differences between men and women.RESEARCH DESIGN AND METHODS -We investigated oxidative status in 29 control subjects and 37 patients with uncomplicated type 1 diabetes with duration of 6 Ϯ 3 years.RESULTS -Compared with control subjects, type 1 diabetic patients had lower total plasma antioxidant capacity (TRAP) (720.3 Ϯ 111.2 vs. 972.5 Ϯ 97.7 mol/l in men, P Ͻ 0.001; 579.8 Ϯ 95.4 vs. 930.1 Ϯ 84.2 in women, P Ͻ 0.001), higher lipid hydroperoxide (ROOH) levels (6.4 Ϯ 2.2 vs. 2.0 Ϯ 0.7 mol/l in men, P Ͻ 0.001; 8.1 Ϯ 1.9 vs. 2.2 Ϯ 0.6 in women, P Ͻ 0.001), higher total conjugated diene (CD) levels (0.037 Ϯ 0.003 vs. 0.033 Ϯ 0.002 A.U. in men, P Ͻ 0.001), lower 246-nm CD levels (0.0032.Ϯ 0.0010 vs. 0.0070 Ϯ 0.0012 A.U. in men, P Ͻ 0.001; 0.0022 Ϯ 0.0011 vs. 0.0072 Ϯ 0.0014 A.U. in women, P Ͻ 0.001), and higher 232-nm CD levels (0.0348 Ϯ 0.0041 vs. 0.0257 Ϯ 0.0022 A.U. in men, P Ͻ 0.001; 0.0346 Ϯ 0.0031 vs. 0.0246 Ϯ 0.0074 A.U. in women, P Ͻ 0.001). Compared with diabetic men, diabetic women had lower TRAP (P Ͻ 0.01), higher ROOH levels (P Ͻ 0.01), and lower 246-nm CD levels (P Ͻ 0.05). Plasma concentration of uric acid was significantly lower in patients with type 1 diabetes than in control subjects (3.3 Ϯ 0.3 vs. 4.3 Ϯ 0.2 mg/dl; P ϭ 0.009) with a significant difference between women and men with type 1 diabetes (2.6 Ϯ 0.3 vs. 3.9 Ϯ 0.3, respectively; P ϭ 0.009).CONCLUSIONS -Our findings suggest that reduced antioxidant activity and increased oxidative stress occur early after the diagnosis of type 1 diabetes, especially in women, and this might explain, at least in part, the increased susceptibility of diabetic women to cardiovascular complications.

Rigby & Stasinopoulos (2005) introduced generalized additive models for location, scale and shape (GAMLSS) where the response distribution is not restricted to belong to the exponential family and its parameters can be specified as functions of additive predictors that allows for several types of covariate effects (e.g., linear, non-linear, random and spatial effects).In many empirical situations, however, modeling simultaneously two or more responses conditional on some covariates can be of considerable relevance. In this article, we extend the scope of GAMLSS by introducing a bivariate copula additive model with continuous margins for location, scale and shape. The framework permits the copula dependence and marginal distribution parameters to be estimated simultaneously and, like in GAMLSS, each parameter to be modeled using an additive predictor. Parameter estimation is achieved within a penalized likelihood framework using a trust region algorithm with integrated automatic multiple smoothing parameter selection. The proposed approach allows for straightforward inclusion of potentially any parametric continuous marginal distribution and copula function. The models can be easily used via the copulaReg() function in the R package SemiParBIVProbit.The usefulness of the proposal is illustrated on two case studies (which use electricity price and demand data, and birth records) and on simulated data.

In the early phase of AMI, serum IGF-1 levels are markedly reduced and may contribute to adverse outcomes. Reduced IGF-1 preceding the rise of myocardial necrosis markers suggests a possible pathogenetic role. A compensatory increase in IGF-1 appears to occur by one year.