Francesco Piarulli

Forearm Nitric Oxide Balance, Vascular Relaxation, and Glucose Metabolism in NIDDM Patients

Endothelium-dependent and -independent vascular responses were assessed in 10 NIDDM patients and 6 normal subjects with no evidence of atherosclerotic disease. Changes in forearm blood flow and arteriovenous (AV) serum nitrite/nitrate (NO2−/NO3-) concentrations were measured in response to intra-arterial infusion of acetylcholine (ACh) (7.5, 15, 30 μg/min, endothelium-dependent response) and sodium nitroprusside (SNP) (0.3, 3, 10 μg/min, endothelium-independent response). Insulin sensitivity (determined by minimal model intravenous glucose tolerance test) was lower in NIDDM patients (0.82 ± 0.20 vs. 2.97 ± 0.29 104 min · μU−1 · ml−1; P < 0.01). Baseline forearm blood flow (4.8 ± 0.3 vs. 4.4 ± 0.3 ml · 100 ml−1 tissue · min−1; NS), mean blood pressure (100 ± 4 vs. 92 ± 4 mmHg; NS), and vascular resistance (21 ± 1 vs. 21 ± 1 units; NS), as well as their increments during ACh and SNP, infusion were similar in both groups. No difference existed in baseline NO2−/NO3− concentrations (4.09 ± 0.33 ]NIDDM patients] vs. 5.00 ± 0.48 μmol/1 ]control subjects]; NS), their forearm net balance (0.31 ± 0.08 ]NIDDM patients] vs. 0.26 ± 0.08 μmol/1 · 100 ml−1 tissue · min−1; NS), and baseline forearm glucose uptake. During ACh infusion, both NO2− and NO3− concentrations and net balance significantly increased in both groups, whereas glucose uptake increased only in control subjects. When data from NIDDM and control groups were pooled together, a correlation was found between the forearm AV NO2− and NO3− differences and blood flow (r = 0.494, P = 0.024). On the contrary, no correlation was evident between NO2− and NO3− concentrations or net balance and insulin sensitivity. In summary, 1) no difference existed in basal and ACh-stimulated NO generation and endothelium-dependent relaxation between uncomplicated NIDDM patients and control subjects; 2) in both NIDDM and control groups, forearm NO2− and NO3− net balance following ACh stimulation was related to changes in the forearm blood flow; and 3) ACh-induced increase in forearm blood flow was associated with an increase in glucose uptake only in control subjects but not in NIDDM patients. In conclusion, our results argue against a role of impaired NO generation and blood flow regulation in determining the insulin resistance of uncomplicated NIDDM patients; rather, it supports an independent insulin regulation of hemodynamic and metabolic effects.

Glyco-oxidation and cardiovascular complications in type 2 diabetes: a clinical update

Diabetes is associated with a greatly increased risk of cardiovascular disease (CVD), which cannot be explained only by known risk factors, such as smoking, hypertension, and atherogenic dyslipidemia, so other factors, such as advanced glycation end-products (AGEs) and oxidative stress, may be involved. In this frame, hyperglycemia and an increased oxidative stress (AGE formation, increased polyol and hexosamine pathway flux, and protein kinase C activation) lead to tissue damage, thus contributing to the onset of cardiovascular complications. Several studies have identified in various cell systems, such as monocytes/macrophages and endothelial cells, specific cellular receptors (RAGE) that bind AGE proteins. The binding of AGEs on RAGE induces the production of cytokines and intracellular oxidative stress, thus leading to vascular damage. Soluble RAGE levels have been identified as hypothetical markers of CVD, but, in this regard, there are sparse and conflicting data in the literature. The purpose of this review was to examine all the available information on this issue with a view to clarifying or at least highlighting the points that are still weak, especially from the point of clinical view.

Reproducibility of Michigan Neuropathy Screening Instrument (MNSI): A comparison with tests using the vibratory and thermal perception thresholds

tion decreased <7% from the beginning to the end of each study. Falsely low results were found in small sample volumes in all monitors except for the MediSense Precision Q.l.D. (Fig. 1). Regarding accuracy, a statistically significant decrease (Students t test, a < 0.05) in mean value compared with that at 20 /xl was found in the following: Flite (1 jul, 59% decrease); Encore (1 and 5 jal, 76% and 22% decrease, respectively); liasy (1 JLLI, 57% decrease); and Advantage (1 and 5 JLLI, 74 and 32% decrease, respectively). In precision, a statistically significant increase (F test, a < 0.05) in variance compared to that at 20 jal was found in the following: Elite (1 /xl, CV of 39.6%); Encore (1, 5 and 10 JLLI, CV of 53.4, 21.9, and 7.7%, respectively); and Easy (1,5, and 10 /xl, CV of 29.9, 8.2, and 17.9%, respectively).

Correlation Between Baseline Characteristics and Clinical Outcomes in a Large Population of Diabetes Patients Treated with Liraglutide in a Real-World Setting in Italy

PURPOSE Treatment with liraglutide in randomized controlled trials is associated with significant reductions in glycated hemoglobin (HbA1c) and weight loss in type 2 diabetes patients. The aim of this retrospective observational study was to investigate correlations of glycemic control and weight outcomes with baseline characteristics of patients starting liraglutide in outpatient clinics in Italy. METHODS Type 2 diabetes patients were followed from baseline to 4, 8, and 12 months. Changes in glycemic parameters, weight, blood pressure, and lipids were assessed. Subanalyses were performed according to baseline characteristics. Multivariate linear and logistic regressions were used to assess correlations between glycemic efficacy, weight reduction, and liraglutide discontinuation after 12 months and baseline characteristics. FINDINGS Four hundred and eighty-one patients were included. Mean (SD) age at baseline was 57.3 (9.2) years, diabetes duration was 9.5 (6.8) years, weight was 106.7 (20.8) kg, body mass index (BMI; calculated as kg/m(2)) was 37.1 (6.6), HbA1c was 8.7% (1.3%), fasting plasma glucose was 168.5 (45.3) mg/dL; 38.2% were treated previously with insulin and 52.2% were treated with metformin alone. After 12 months, mean (SD) changes were HbA1c -1.2% (1.4%), fasting plasma glucose -28.3 (41.1) mg/dL, weight -3.5 (5.8) kg, BMI -1.3 (2.1), waist circumference -2.6 (6.7) cm (all, P < 0.001). Drop in weight and HbA1c did not differ between baseline BMI classes ≤30 or >30. Weight loss was unchanged among diabetes duration quartiles, and HbA1c reduction was significantly greater in patients with ≤4 years of diabetes duration (P = 0.01). Non-insulin-treated patients reached HbA1c ≤7% significantly more often than treated patients (44.2% vs 21.2%; odds ratio = 2.94; P < 0.001) and had significantly greater weight loss (-4.5 [8.2] kg vs -2.6 [5.4] kg; P = 0.03). Patients on metformin reached HbA1c target more frequently than others (43.1% vs 29.7%; odds ratio = 1.80; 95% CI, 1.05-3.07). Significant positive determinants for HbA1c reduction after 12 months were baseline HbA1c, age, and prior metformin monotherapy, and weight loss at 12 months was positively correlated with baseline weight, and negatively correlated with prior insulin treatment. Overall, 5.0% of patients interrupted liraglutide before the 12th month due to lack of glycemic control; they were less frequently treated with metformin only before liraglutide (29.2% vs 50.2%; P = 0.04). IMPLICATIONS Treatment with liraglutide in a real-world setting is associated with low therapy failure, good glycemic response, weight loss, and improvement in systolic blood pressure and lipid profile. The HbA1c drop did not differ among baseline BMI classes, indicating that efficacy is maintained in patients with lower BMI. The probability of reaching HbA1c ≤7% was significantly higher in patients previously treated with metformin alone and without any previous insulin. This could reinforce the hypothesis that better results with liraglutide could be achieved in patients after early metformin failure.

Clinical Assessment of Low Molecular Weight Heparin Effects in Peripheral Vascular Disease

This study was carried out, using the double-blind method vs placebo, on 36 patients suffering from stage II peripheral vascular disease (PVD) according to Leriche, to check the clinical and hemorrheologic effects of the administration of a new low molecular weight heparin (LMWH). After a one-month washout period, the patients were randomly assigned either to the group treated with the LMWH (15,000 aXaU/day sc) or to the group treated with indistinguishable placebo. At the start of the study and after three and six months of treatment, clini cal, instrumental, and laboratory tests were performed to assess local and sys temic efficacy and tolerance. The LMWH under study caused a statistically significant increase in claudi cation time, with a parallel increase in the absolute claudication distance and in the interval free of pain. The drug also led to a significant increase in activated partial thromboplastin time, the values of which, however, remained within the normal limits, and to a marked reduction in blood viscosity. No significant vari ation was observed in the tolerability parameters in the two treatment groups, and no local or systemic adverse reactions occurred.

Calf and forearm blood flow in hypercholesterolemic patients.

Patients with hypercholesterolemia without vascular disease have an impaired endothe lium-dependent (nitric oxide-mediated) vasodilation in coronary and peripheral vascular beds. This study was designed to establish whether hypercholesterolemia (and its reduction) affects also the microcirculation vasomotion during postischemic hyperemia in both calf and forearm. Thirteen male patients, aged 36.2 ±8.5 years, mean ±SD, with heterozygous familial hypercholesterolemia and 10 male control subjects, aged 32.2 ±3.6 years free from vascular lesions were studied. Plasma lipids, hematologic parameters, and limb vasoreactivity were evaluated while the patients were treated only with diet and during therapy with simvastatin. Calf and forearm blood flows were determined by venous occlusion strain gauge plethysmography at rest, during reactive hyperemia, and after sublingual isosorbide dinitrate administration. Calf resting flow rate of the hyperc holesterolemic patients during and without treatment was similar to that of the controls. Calf resting vascular resistance was greater in the untreated hypercholesterolemic subjects than in the normal controls, but during treatment this difference was abolished. Peak flow during reactive hyperemia and flow debt repayment were lower in the untreated hypercholesterolemic subjects as compared to the controls, but they were normalized following hypocholesterolemic therapy. No differences were observed in forearm blood flow measurements between hypercholesterolemic subjects (without and during therapy) and control subjects. The blood flow and vascular resistance after isosor bide dinitrate were modified in a similar manner in the hypercholesterolemic (without and during therapy) and control subjects at both calf and forearm. Hypercholesterolemia does not affect vasodilation in the forearm as determined by postocclusive reactive hyperemia, while in the calf hypercholesterolemia is associated with higher resting vascular resistance, lower peak flow during reactive hyperemia, and lower flow debt repayment. These abnormalities are corrected by the hypocholesterolemic treatment.

Insulin sensitivity correlates with glycogen synthesis rate, but not with von Willebrand factor in type 2 diabetes

BACKGROUND: Whether insulin resistance in type 2 (non-insulin-dependent) diabetes is due to compromised endothelial insulin migration or to impaired intracellular hormone action or both is unclear. Coexistent microalbuminuria reflects possible endothelial pathogenesis in insulin resistance. METHODS: Insulin sensitivity (S(I)) was calculated from an intravenous glucose tolerance test in 23 type 2 albuminuric (AER+), 11 type 2 normoalbuminuric (AER-), and 17 control subjects. Cultured fibroblasts from skin biopsies from these subjects were used to study intracellular insulin action on glycogen synthesis. Endothelial damage in type 2 diabetes was evaluated by plasma concentrations of von Willebrand factor (vWf). Results: S(I) and glycogen synthesis in fibroblasts were lower in AER+ and AER- than in controls. Glycogen synthesis in vitro was related to S(I) in vivo (r=0.55, P<0.001). vWf was 169+/-12% in AER+ and 140+/-5% in AER-, P<0.051. No correlation was observed between vWf and S(I) or plasma insulin clearance. CONCLUSIONS: This study demonstrates that reduced insulin-mediated glucose removal in type 2 diabetes is strictly associated with a decreased glycogen synthesis of cultured skin fibroblasts in vitro, but not with markers of endothelial damage in vivo.

The Hemodynamic Abnormalities in Short-Term Insulin Deficiency: The Role of Prostaglandin Inhibition

It has been suggested that the hemodynamic derangements present in diabetic ketoacidosis are the results not only of profound volume depletion but also of the effects of increased production of vasodilating prostaglandins (PGs), principally PGI2, released by adipose tissue. In animal and in vitro models, prostaglandin synthesis is increased during insulin deficiency. We assessed the effects of short-term ketosis on the metabolic and hemodynamic variables of 10 IDDM patients free from long-term complications and of 9 normal control subjects after a 7-day randomized double-blind indomethacin (INDO) (50 mg q.i.d.) or placebo treatment period. Calf blood flow (CBF), postocclusive reactive hyperemia (PORH), and recovery half-time (an index of overall perfusion) after PORH were measured by plethysmography. Left ventricular and myocardial functions were also studied in each different condition during placebo and INDO treatment in IDDM patients. During placebo treatment, the increase in CBF during ketosis was higher (1.75 ± 0.29 ml · min−1 · 100 ml muscle−1) than during INDO (0.85 ± 0.17 ml · min−1 · 100 ml muscle−1; P = 0.007). PORH was similar in baseline conditions, during ketosis, and in recovery in both the placebo and INDO arms. Recovery half-time significantly increased during placebo (10 ± 2; 200%; P < 0.01) but not during INDO (1 ± 1; 106%; NS) treatment. In normal control subjects, insulin deficiency did not induce any significant effect on hemodynamic variables. In IDDM patients, during placebo treatment, ketosis increased both the cardiac index (from 3.4 ± 0.7 to 4.1 ± 0.8 1 · min−1 · m−2; P < 0.01) and the stroke index (from 42 ± 8 to 49 ± 7 ml/m2; P < 0.01) without changes in left ventricular ejection fraction but with a significant increase in both left and right ventricular end-diastolic volumes. Metabolic recovery induced a normalization of these parameters. INDO treatment significantly blunted these alterations. In summary, we showed that during acute insulin deficiency, INDO-sensitive mechanisms mediate vascular disturbances. Moreover, INDO treatment was capable of completely preventing the cardiac venous return and the left ventricular alterations. INDO does not interfere with the overall ketogenetic process or with insulin-induced metabolic recovery.

A preliminary fastview of mitochondrial protein profile from healthy and type 2 diabetic subjects.

Type 2 diabetes results from the development of insulin resistance and a concomitant impairment of insulin secretion. Mitochondrial dysfunctions are thought to be the major contributor to the development of various pathologies, including type 1 and type 2 diabetes mellitus. Mitochondrial oxidative stress has been reported in models of both type 1 and type 2 diabetes mellitus and may play a central role in mitochondrial dysfunction. In the present study, we investigated the occurrence of protein alterations, due to the presence of type 2 diabetes, in mitochondria isolated from human peripheral blood mononuclear cells (PBMCs) by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). PBMCs may be suitable for this investigation because they have insulin receptors that quickly respond to changes in insulin concentration, and in the presence of insulin rapidly increase their rates of glucose utilization. In the presence of insulin-resistance conditions, such as type 2 diabetes mellitus, this mechanism is altered and the glycation of cytoplasmic as well as mitochondrial proteins may plausibly appear. Therefore, PBMCs may be useful tools to verify modifications or altered expression of mitochondrial proteins. Human mitochondria were obtained from 32 subjects, 16 healthy controls and 16 type 2 diabetic patients. Two different methods for mitochondria isolation and purification were employed and compared. Some proteins have been found to be differently expressed in the two groups of subjects under investigation and can be classified into two sets: i.e. proteins related to ATP synthase [e.g. 6.8 kDa mitochondrial proteolipid (MLQ); ATP-CF6 (m/z 12,597)] and proteins related to cell proliferation and apoptosis [e.g. TIMM9 (m/z 10,378); Bcl-2-like protein 2 (m/z 20,742)].

Mild peripheral neuropathy prevents both leg muscular ischaemia and activation of exercise-induced coagulation in Type 2 diabetic patients with peripheral artery disease

Aim  To study the influence of peripheral neuropathy on intermittent claudication in patients with Type 2 diabetes (T2DM).