Plasminogen activator inhibitor-1 synthesis in the human hepatoma cell line Hep G2. Metformin inhibits the stimulating effect of insulin.

High plasma plasminogen activator inhibitor-1 (PAI-1) activity is associated with insulin resistance and is correlated with hyperinsulinemia. The cellular origin of plasma PAI-1 in insulin resistance is not known. The hepatoma cell line Hep G2 has been shown to synthesize PAI-1 in response to insulin. The aim of this study was to analyze the insulin-mediated response of PAI-1 and lipid synthesis in Hep G2 cells after producing an insulin-resistant state by decreasing insulin receptor numbers. The effect of metformin, a dimethyl-substituted biguanide, known to lower plasma insulin and PAI-1 levels in vivo was concomitantly evaluated. Preincubation by an 18-h exposure of Hep G2 cells to 10(-7) M insulin aimed at reducing the number of insulin receptors, was followed by a subsequent 24-h stimulation with 10(-9) M insulin. The decrease in insulin receptors was accompanied as expected, by a reduction in [14C]acetate incorporation, an index of lipid synthesis, whereas PAI-1 secretion and PAI-1 mRNA expression were enhanced. The addition of metformin did not modify the effect of insulin on insulin receptors or [14C]acetate incorporation. In contrast, the drug (10(-4) M) inhibited insulin-mediated PAI-1 synthesis. The results indicate that PAI-1 synthesis in presence of insulin is markedly increased in down-regulated cells, and that metformin inhibits this effect by acting at the cellular level. These in vitro data are relevant with those found in vivo in insulin-resistant patients. Hep G2 cells may be a suitable model to study PAI-1 regulation in response to hyperinsulinemia.

C-peptide replacement improves weight gain and renal function in diabetic rats.

AIM: Recent experimental and clinical data suggest that C-peptide replacement during type 1 diabetes exerts beneficial effects on diabetic nephropathy. The aim of this study was to determine if physiological C-peptide administration in replacement dose during 28 days had beneficial effects on metabolic status and renal functions in type-1 diabetic rats. METHODS: Four groups of rats were investigated: a non diabetic group treated with buffer (C group, n=6), three streptozotocin diabetic-induced groups treated with either buffer (D group, n=6), insulin (D-I group, n=6) or rat homologous C-peptide (D-C group, n=6). Weight gain was measured every week. All animals were housed in metabolic cages on day 28 for assessment of metabolic data. Blood and urine samples were collected to allow measurement of plasmatic osmolality, C-peptide concentration, sodium, and glucose losses and proteinuria. Glomerular filtration rate (GFR) was determined by creatinine clearance. RESULTS: All streptozotocin-treated animals were diabetic. Glycaemic control (mg/dl), was markedly improved in D-I (133+/-65) when compared with either D (547+/-49, P<0.05) or D-C (520+/-48, P<0.05) groups. Conversely, weight gain during the study, was improved in D-I and D-C as compared with D animals (135+/-13 and 41+/-18 vs 18+/-21 respectively), despite different glycaemic control. Diabetes-induced glomerular hyperfiltration (ml/min/kg), urinary protein leakage (g/kg/day), and Na urinary losses (mmol/100 g/day) respectively, were significantly (P<0.05) reduced in D-C (3.95+/-0.6; 0.08+/-0.06; 1.5+/-0.9) in comparison with D (4.95+/-0.8; 0.18+/-0.16; 3.7+/-2.1) and D-I (5+/-0.9; 0.19+/-0.11; 2.7+/-0.8) animals. Plasmatic osmolality was significantly increased in D group whereas there were no differences between C group and D-C group. Food and water intakes, urinary volume as well as urinary glucose losses were not significantly different between D-C and D groups. CONCLUSIONS: C-peptide administration in replacement dose to streptozotocin diabetic rats induces weight gain regardless hyperglycaemia or glycosuria. Diabetic animals supplemented with C-peptide exhibit better renal function resulting in reduced urinary sodium waste and protein excretion together with reduction of the diabetes-induced glomerular hyperfiltration.

Red cell deformability, platelet aggregation, and insulin action.

Abnormalities of rheologic and hemostatic properties of blood are present in uncontrolled diabetics and play a role in the development of structural micro- and macroangiopathies. Red blood cell deformability is decreased in diabetics and shows negative correlation with fast hemoglobin and actual blood glucose levels. In uncontrolled insulin-dependent diabetics, normalization of plasma glucose by an insulin infusion improves red cell deformability in 2 h. Insulin infusion (0.2 U/kg/h) [the initial hyperglycemia being maintained (hyperglycemic clamp)] also improves red cell deformability. Deformability of normal erythrocytes is reduced by incubation in plasma from uncontrolled diabetics but is normal in plasma from diabetics controlled by a 24-h insulin infusion or in diabetic plasma with insulin added in vitro. Therefore, insulin appears to have a direct effect on erythrocyte deformability. Platelet aggregation measured in whole blood is raised in uncontrolled diabetics. Aggregation of normal platelets rises in the presence of "diabetic" red cells but not in the presence of red cells from the same patients controlled by 24-h treatment with insulin. The effect of insulin on platelet aggregation, therefore, seems to be at least partly mediated by erythrocytes.

Low plasma levels of pancreatic polypeptide in obesity.

Plasma levels of pancreatic polypeptide (PP) were studied in a group of 22 normal and 22 obese subjects after an overnight fast. In a second group of 10 normal and 13 obese adults, PP secretion was stimulated by a protein-rich meal. The results indicate lower fasting PP values in the obese subjects and a decreased response during the second phase of the meal-induced secretion. This could suggest a possible role of PP in obesity.

In vivo insulin effect on ATPase activities in erythrocyte membrane from insulin-dependent diabetics.

Na+-K+-dependent ouabain-sensitive ATPase and Mg2+-ATPase have been assayed in the erythrocyte membranes of control subjects and in uncontrolled type I (insulin-dependent) diabetics. A decrease in Na+-K+-ATPase activity was observed in the patients that was significantly correlated with glycemia. The Mg2+-ATPase was increased moderately, and no correlation with glycemia was found. To study the in vivo effect of insulin, ATPase activities were measured in uncontrolled diabetics before and after a 24-h continuous insulin perfusion administered by means of an artificial pancreas. ATPase activities were corrected after normalization of glycemia. It therefore seems that glycemia and/or insulinemia are involved in the regulation of erythrocyte Na+-K+ ouabain-sensitive ATPase and to a lesser extent in that of Mg2+-dependent ATPase.

Plasma C-peptide levels and clinical remissions in recent-onset type I diabetic patients treated with cyclosporin A and insulin.

Remission from insulin dependency in insulin-treated recent-onset type I (insulin-dependent) diabetic patients can result from a partial recovery of insulin secretion, an improvement in tissue sensitivity to insulin, or both. The same hypothesis must be analyzed when remission occurs in cyclosporin A (CsA)-treated patients. In this study, plasma C-peptide levels were serially measured in the basal state and after stimulation in 219 recent-onset type I diabetic patients; 129 received CsA, and all patients were similarly monitored and insulin treated. The results were analyzed in view of the occurrence of remission. Remission was defined as good metabolic control in the absence of hypoglycemic treatment for greater than or equal to 1 mo. Remission occurred in 44% of the CsA-treated group and lasted for mean +/- SE 10.0 +/- 0.9 mo vs. 21.6% in the non-CsA-treated group with a duration of 4.4 +/- 0.8 mo. Plasma C-peptide levels were initially dramatically lower than normal in both groups in the basal and stimulated states. C-peptide levels increased significantly later, at 3 and 6 mo, in both groups. C-peptide values were proportional to the rates of remission in both groups. In the non-CsA-treated group, C-peptide levels later decreased, and these patients inexorably relapsed to insulin dependency. In contrast, in the CsA-treated group, the initial recovery in insulin secretory capacity was maintained over the 18-24 mo of the study. Furthermore, higher remission rates and longer-lasting remission were obtained in patients who reached higher C-peptide levels at the 3rd mo of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucocorticoids and insulin promote plasminogen activator inhibitor 1 production by human adipose tissue.

Plasminogen activator inhibitor 1 (PAI-1) is likely to play a role in vascular disease, primarily in subjects with android obesity. It has been demonstrated that PAI-1 is overexpressed in adipose tissue from obese subjects and that visceral adipose tissue produced more PAI-1 than subcutaneous fat. In the present study, the effect of insulin and glucocorticoids, which are key mediators of adipose tissue metabolism, was examined in relation to PAI-1 synthesis by human adipose tissue explants (HAT), collagenase isolated human adipocytes (IHA), cultured human stromal cells (cSC), and differentiated adipocytes from the murine clonal cell line 3T3-F442A. A significant increase in PAI-1 antigen release (1.5-fold) from HAT was detectable after 16 h of treatment with insulin concentrations of at least 10(-8) mol/l. This was associated with a PAI-1 mRNA increase. Concomitant addition of insulin (10(-8) mol/l) to forskolin (5 x 10(-5) mol/l) reversed the decrease in PAI-1 antigen caused by forskolin alone. No effect on PAI-1 antigen was observed when insulin was incubated with IHA or cSC. 3T3 F442A cells were sensitive to insulin with a four- and twofold increase in PAI-1 antigen and mRNA levels, respectively, after 16 h of stimulation with 10(-8) mol/l. Dexamethasone (DXM) significantly enhanced PAI-1 antigen and mRNA expression by HAT (1.5- and 2.5-fold increase, respectively) at concentrations of at least 10(-8) mol/l. A higher stimulation was observed with IHA (sevenfold increase) and with the differentiated 3T3 F442 cell line. Cortisol was found to be less potent than DXM. No effect was observed when glucocorticoids were incubated with cSC. Coincubation of HAT with insulin (10(-7) mol/l) and DXM (10(-7) mol/l) led to an additive effect on PAI-1 synthesis. These results support the hypothesis that PAI-1 expression in human adipose tissue is controlled by insulin and glucocorticoids and may help to explain the increase in plasma PAI-1 levels observed in patients with android obesity.

Factors related to CSII compliance.

Many studies have demonstrated the metabolic efficacy of continuous subcutaneous insulin infusion (CSII) and particularly a reduction of glycaemic fluctuations in type 1 diabetic patients. Despite this benefit, many patients decide to discontinue the use of CSII. To determine the factors related to discontinuation of CSII we analyzed clinical data from a group of 70 patients who had been consecutively started on this treatment from April 2000 to April 2002. Patients were followed for up to 2 years. Eighteen (25.7%) patients decided to terminate CSII during the study after an average of 235 days (range 21-293). The reasons for stopping CSII were decision of the patients (10), end of pregnancy (4), needle site infections (3) and lack of compliance (1). No significant difference was found between patients who had continued and those who had discontinued CSII for age, duration of diabetes, reasons for starting CSII, marital status, prepump concentration of HbA1c and prepump frequency of hypoglycaemia. There tend to be more discontinuations for pregnant women, patients attending hospital visits versus liberal practitioner and patients with lower educational level (below or over baccalaureat) although none of these differences was statistically significant. In conclusion we could not identify any predictive factor of CSII discontinuation.

Accumulation of triglyceride-rich lipoprotein in subjects with abdominal obesity: the biguanides and the prevention of the risk of obesity (BIGPRO) 1 study.

The present study represents a new insight into the Biguanides and the Prevention of the Risk of Obesity (BIGPRO) 1 study population at inclusion. This population, selected basically on the basis of a high waist-to-hip ratio (>/=0.95 for men and >/=0.80 for women), is supposed to represent a group of patients with insulin resistance. The present study was undergone to establish whether apolipoprotein C-III (apoC-III) and apolipoprotein E (apoE) associated with apo B (apoC-III LpB and apoE LpB, respectively), considered to be markers of remnant accumulation, play a role in the hypertriglyceridemia associated with insulin resistance and whether they are related to other biological abnormalities frequently observed in this syndrome. In this population, the concentration of the markers of remnant accumulation increases with triglyceride levels. Therefore, correlation studies were realized to assess the relative effect of insulin and the markers of remnant accumulation on triglyceride plasma level. As a first attempt, a simple correlation analysis revealed that insulin is positively related to the markers of remnant accumulation only in hypertriglyceridemic patients (triglycerides >/=1.7 mmol/L). To assess the independent contribution of these markers, insulin, and other parameters related to the plasma triglyceride concentration, a stepwise multiple regression analysis was run. Results revealed that insulin and the markers of remnant accumulation (specifically, apoE LpB) are independent contributors to the plasma triglyceride concentration. Markers of the endothelial damage, plasminogen activator inhibitor-1, tissue plasminogen activator, and von Willebrand factor, which are often increased in the case of insulin resistance, were tested for their correlation with the markers of remnant accumulation. Plasminogen activator inhibitor-1 is positively correlated with these markers only in hypertriglyceridemic male subjects. It is concluded that increased insulin levels found in insulin resistance syndrome are associated with an increased production of triglyceride-rich lipoproteins enriched in apoC-III and apoE. The accumulation of these remnants and/or their abnormal composition in apoC-III and apoE could be an explanation for the development of hypertriglyceridemia in this syndrome.

Erythrocyte Na(+)-K(+)-ATPase activity, metabolic control, and neuropathy in IDDM patients.

OBJECTIVE: To study the relationship among red blood cell Na(+)-K(+)-ATPase activity, metabolic control, and diabetic neuropathy. RESEARCH DESIGN AND METHODS: Na(+)-K(+)-ATPase activity has been measured in the red cell membrane of 43 long-standing IDDM patients (duration of diabetes 17.5 +/- 2 years, mean +/- SE), with 20 of the patients presenting with peripheral neuropathy. There were 23 healthy subjects serving as the control group. RESULTS: Na(+)-K(+)-ATPase activity was significantly lower in diabetic patients than in healthy subjects (236.5 +/- 7.5 vs. 294 +/- 10 nmol P1 . mg protein-1 . h-1, P < 0.05). Among diabetic patients, Na+/K(+)-ATPase activity was not dependent on the degree of diabetic control, nor was it correlated with either fasting blood glucose (r = 0.16, NS) or HbA1 (r = 0.01, NS). Na(+)-K(+)-ATPase activity was lower in patients with neuropathy than in those without it (212 +/- 8.5 vs. 261 +/- 6.6, P < 0.05). Furthermore, in a subgroup of 20 patients, a positive correlation was observed between erythrocyte Na(+)-K(+)-ATPase activity and nerve conduction velocity in the peroneal (r = 0.558, P < 0.02) and tibial nerve (r = 0.528, P < 0.05). CONCLUSIONS: These results suggest that diabetes-induced Na(+)-K(+)-ATPase activity dysfunction could be implicated in the pathogenesis of human diabetic neuropathy and the electrophysiological abnormalities observed in these patients.

Silent myocardial ischemia in patients with diabetes: who to screen.

OBJECTIVE: Silent myocardial ischemia (SMI) is more common in diabetic patients than in the general population. However, the exact prevalence of SMI is not known, and routine screening is costly. The purpose of this 1-year study was to estimate the prevalence of SMI and define a high-risk diabetic population by systematically testing patients with no symptoms of coronary artery disease (CAD). RESEARCH DESIGN AND METHODS: The criteria for inclusion in this study were age (between 25 and 75 years), duration of diabetes (>15 years for type 1 diabetes, 10 years for type 2 diabetes with no cardiovascular risk factors, and 5 years for type 2 diabetes with at least one cardiovascular risk factor), and absence of clinical or electrocardiogram (ECG) symptoms of CAD. For 1 year, 203 patients were screened, including 28 women and 45 men with type 1 diabetes (aged 41.5+/-10.9 years, mean duration of diabetes 20.9+/-7.7 years [mean +/- SD]) and 61 women and 69 men with type 2 diabetes (aged 60.7+/-8.7 years, duration of diabetes 16.5+/-7.1 years). Exercise ECG was the first choice for screening method. If exercise ECG was not possible or inconclusive, thallium myocardial scintigraphy (TMS) with exercise testing and/or dipyridamole injection was performed. If any one of these tests was positive, coronary angiography was carried out and was considered to be positive with a stenosis of > or =50%. RESULTS: Positive screening results were obtained in 32 patients (15.7%). Coronary angiography demonstrated significant lesions in 19 patients (9.3%) and nonsignificant lesions in 7 patients (1 false-positive result for exercise ECG and 6 false-positive results for TMS). Coronary angiography was not performed in six patients. All but 3 of the 19 patients (15 men and 4 women) in whom silent coronary lesions were detected presented with type 2 diabetes. The main differences between the 16 type 2 diabetic patients presenting with coronary lesions and the type 2 diabetic patients without SMI were a higher prevalence of peripheral macroangiopathy (56.2 vs. 15.1%, respectively, P < 0.01) and a higher prevalence of retinopathy (P < 0.05). No correlation was found between SMI and duration of diabetes, HbA1c level, renal status, or cardiovascular risk factors except for family history of CAD. CONCLUSIONS: The results of this study allowed us to determine a high-risk group for SMI in the diabetic population. SMI with significant lesions occurs in 20.9% of type 2 diabetic male patients who are totally asymptomatic for CAD. Based on these findings, we recommend routine screening for male patients in whom the duration of type 2 diabetes is >10 years or even less when more than one cardiovascular risk factor is present.

Immunogenicity of long-term intraperitoneal insulin administration with implantable programmable pumps. Metabolic consequences.

OBJECTIVE: To assess immunogenicity of intraperitoneal insulin infusion via implanted pumps by two methods and to evaluate the possible influence of an increased antibody level on metabolic and clinical parameters. RESEARCH DESIGN AND METHODS: We studied insulin antibody levels in 17 type I diabetic patients before and until 24 months after implantation of a programmable pump delivering insulin intraperitoneally. Antibody levels were determined by radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA). They were correlated with HbA1c, insulin requirements, free insulin, and the incidence of hypoglycemia. RESULTS: Insulin antibodies increased as soon as the 3rd month after implantation. This increase was sustained throughout the study period (month 0, 25.4 +/- 16.2%; month 3, 41.2 +/- 23.5%; month 12, 45.9 +/- 26%; month 24, 48.7 +/- 25%). The data was correlated with the two assay methods (RIA and ELISA). Postimplantation level was correlated with preimplantation level, which could indicate a predictive value of the latter . No correlation was observed with any metabolic parameters, particularly the number of hypoglycemic episodes. CONCLUSIONS: Our results indicate that intraperitoneal insulin administration by implantable programmable pumps leads to an increase of insulin antibodies, which are probably high-affinity antibodies (recognized by both RIA and ELISA). This increase in insulin immunogenicity did not induce significant metabolic consequences, which is reassuring for the future of programmable insulin pumps.

Acute insulin response to glucose and glucagon in subjects at risk of developing type I diabetes.

OBJECTIVE: To determine if knowledge of characteristics of insulin response to various secretagogues during the preclinical phase of type I diabetes may facilitate the diagnosis of subjects at risk. RESEARCH DESIGN AND METHODS: A test consisting of sequential intravenous challenge with glucose (0.3 g/kg) and glucagon (1 mg, 10 min after the end of glucose injection) was performed on 171 ICA- relatives of type I diabetic patients, 18 ICA+ relatives of type I diabetic patients, and 5 transiently hyperglycemic subjects. Acute response to glucose was expressed as the sum of plasma insulin at 2 and 5 min and response to glucagon as the increase in plasma insulin after 10 min. RESULTS: Responses below the lower 95% confidence interval in the ICA- population (40 and 43 microU/ml for glucose and glucagon, respectively) were considered abnormal. The two values were correlated (r = 0.62). Abnormalities coexisted in 2.3% of the ICA- group, 11% of the ICA+ group, and 100% of the transiently hyperglycemic group. All the relatives who subsequently developed diabetes or hyperglycemic subjects who required insulin exhibited combined abnormalities. Some ICA- and ICA+ relatives were tested repeatedly over a follow-up period of 1.5-4 yr. Although the intraindividual coefficient of variation for the two responses was high (28 and 30%), values tended to run parallel in both ICA+ and ICA- relatives. In 2 patients monitored for 2 and 4 yr before diabetes developed, both responses declined at the same rate. In terms of prediction of diabetes, sensitivity of combined abnormalities was high (100%). But compared with the intravenous glucose tolerance test, improvement of specificity by the double challenge was not statistically significant. CONCLUSIONS: Both insulin responses to glucose and glucagon are related. They depend on the secretory capacity of beta-cells and simultaneously become abnormal in the prediabetic phase.

Effect of weight change and metformin on fibrinolysis and the von Willebrand factor in obese nondiabetic subjects: the BIGPRO1 Study. Biguanides and the Prevention of the Risk of Obesity.

OBJECTIVE: Insulin resistance is associated with hypofibrinolysis. Metformin has been shown to improve insulin sensitivity and fibrinolysis. Its action on fibrinolysis and the von Willebrand factor was evaluated in the Biguanides and the Prevention of the Risk of Obesity (BIGPRO)1 trial in nondiabetic men (n = 151) and women (n = 306) aged between 34 and 65 years with a central fat distribution and a mean BMI of 32.5 kg/m2. RESEARCH DESIGN AND METHODS: The subjects were randomly allocated to a 1-year treatment with metformin (850 mg b.i.d.) or placebo, in addition to diet and exercise recommendations. RESULTS: Plasminogen activator inhibitor 1 (PAI-1) activity and antigen decreased significantly but similarly by 30 and 40%, respectively, in both the placebo and the metformin groups. This decrease occurred mainly in subjects who lost weight. Metformin did not have any significant additional effect on PAI-1. In contrast to the results for PAI-1, there was a significantly greater decrease in tissue-type plasminogen activator (tPA) antigen in the metformin than in the placebo group (mean+/-SD: -1.1+/-3.1 vs. 0.2+/-3.2 ng/ml, P < 0.02). The von Willebrand factor (vWF) also decreased significantly more in the metformin group (-0.17+/-0.42 vs. -0.05+/-0.38 U/I, P < 0.02). CONCLUSIONS: Weight loss was the main factor associated with the decrease in PAI-1, in accordance with the recent demonstration of production of PAI-1 by adipocytes. Metformin had a significant effect on two factors, tPA antigen and vWF, mainly secreted by the endothelial cells, which suggests an effect of the drug on the production or the metabolism of these two hemostatic proteins.

Insulin-induced lipoatrophy in type I diabetes. A possible tumor necrosis factor-alpha-mediated dedifferentiation of adipocytes.

OBJECTIVE: To test the hypothesis that tumor necrosis factor (TNF)-alpha may mediate the loss and the dedifferentiation of subcutaneous fat tissue in the insulin-induced lipoatrophies of a diabetic patient who presented extensive lesions. RESEARCH DESIGN AND METHODS: An in vitro exploration of cytokine production by peripheral blood mononuclear cells (PBMC) from the reported case was performed and compared with the same explorations of PBMC from three nondiabetic subjects and three diabetic patients without lipoatrophic lesions. A proliferation test and an evaluation of TNF-alpha and interleukin (IL)-6 production from PBMC in presence of insulin were studied. RESULTS: The production of TNF-alpha and IL-6 by the macrophages of the patient in presence of insulin were dramatically increased in comparison with control subjects. This process needed cooperation with other lymphoid cells and was abrogated by dexamethasone. CONCLUSIONS: In our reported case, a local hyperproduction of TNF-alpha from macrophages that was induced by the injected insulin could explain the dedifferentiation of the adipocytes of the subcutaneous tissue and the reversion that was induced by the local injection of dexamethasone.

The effect of metformin on the metabolic abnormalities associated with upper-body fat distribution. BIGPRO Study Group.

OBJECTIVE: The constellation of anomalies associated with insulin resistance is a plausible additional cause of ischemic cardiovascular disease and of NIDDM. To test this hypothesis in a primary prevention trial, the effects of metformin as a potential candidate for intervention in the insulin resistance syndrome (IRS) were evaluated in 324 middle-aged subjects with upper-body obesity. RESEARCH DESIGN AND METHODS: Trial patients were selected on the basis of a high waist-to-hip ratio. They were randomly allocated to receive either metformin or placebo, following a double-blind procedure. After 1 year of treatment, the main clinical and biological parameters of the IRS were assessed and their evolution compared between treatment groups. RESULTS: Compared with placebo, metformin induced a significant weight loss, a better maintenance of fasting blood glucose, total and LDL cholesterol levels, and a greater decrease of fasting plasma insulin concentration. Moreover, tissue-type plasminogen activator antigen, a marker of fibrinolytic impairment, showed a significant decrease under metformin. By contrast, metformin treatment had no significant effect on blood pressure or serum triglyceride and HDL cholesterol concentrations. The main side effect of metformin was diarrhea. CONCLUSIONS: The BIGuanides and Prevention of Risks in Obesity (BIGPRO1) results suggest that metformin would be a suitable candidate for long-term intervention for the prevention of diabetes but that its use in a trial of primary prevention of cardiovascular diseases requires either a reevaluation of its properties toward the most potentially atherogenic anomalies of the IRS or a better definition of the target population.

Long-term maintenance of weight loss after a very-low-calorie diet: a randomized blinded trial of the efficacy and tolerability of sibutramine.

BACKGROUND: Very-low-calorie diets are a well established method to achieve substantial short-term weight loss in obese patients, but long-term maintenance of the weight loss is very disappointing. A combined very-low-calorie diet and pharmacologic approach could be an effective means of prolonging its benefits. PATIENTS AND METHODS: Eligible patients had a body-mass index greater than 30 kg/m2; those who lost 6 kg or more during a 4-week treatment with a very-low-calorie diet were randomly assigned to 1 year of treatment with sibutramine (10 mg) or identical placebo. RESULTS: In an intention-to-treat analysis, mean (+/-SD) absolute weight change at 1 year (or study endpoint) was -5.2 (+/-7.5) kg in the 81 patients in the sibutramine group and +0.5 (+/-5.7) kg in the 78 patients in the placebo group (P = 0.004). When compared with their weight at study entry (before the very-low-calorie diet), 86% of patients in the sibutramine group had lost at least 5% of their weight, compared with only 55% of those in the placebo group (P <0.001) at the study endpoint. Similarly, at month 12, 75% of subjects in the sibutramine group maintained at least 100% of the weight loss achieved with a very-low-calorie diet, compared with 42% in the placebo group (P <0.01). CONCLUSION: Following a very-low-calorie diet, sibutramine is effective in maintaining and improving weight loss for up to 1 year.

A quantitative immunocytochemical study of Na+,K+-ATPase in rat hepatocytes after STZ-induced diabetes and dietary fish oil supplementation.

Because diabetes causes alterations in hepatic membrane fatty acid content, these changes may affect the Na+,K+-ATPase. In this study we documented the effects of streptozotocin (STZ)-induced diabetes on hepatic Na+,K+-ATPase catalytic alpha1-subunit and evaluated whether these changes could be normalized by fish oil supplementation. Two groups of diabetic rats received fish oil or olive oil supplementation. Both groups had a respective control group. We studied the localization of catalytic alpha1-subunit on bile canalicular and basolateral membranes using immunocytochemical methods and confocal laser scanning microscopy, and the Na+, K+-ATPase activity, membrane fluidity, and fatty acid composition on isolated hepatic membranes. A decrease in the alpha1-subunit was observed with diabetes in the bile canalicular membranes, without changes in basolateral membranes. This decrease was partially prevented by dietary fish oil. Diabetes induces significant changes as documented by enzymatic Na+,K+-ATPase activity, membrane fluidity, and fatty acid content, whereas little change in these parameters was observed after a fish oil diet. In conclusion, STZ-induced diabetes appears to modify bile canalicular membrane integrity and dietary fish oil partly prevents the diabetes-induced alterations.

Increased plasminogen activator inhibitor activity in non insulin dependent diabetic patients--relationship with plasma insulin.

Type 2 diabetic patients are known to frequently have a high insulin level and were recently described as having high plasminogen activator inhibitor (PAI) activity, compared to normal controls. As we have shown in several clinical conditions (normal subjects, obese patients, angina pectoris patients) that plasma PAI activity was linked with plasma insulin, we have studied in 38 type 2 diabetic patients the relationship between PAI activity, insulin and other parameters. Patients showed higher level of PAI activity, as well as plasma glucose, insulin, triglyceride, cholesterol and Apolipoprotein B levels than normal controls; highest values were observed with diabetic patients also affected by coronary artery disease. A significant correlation was found between PAI activity and insulin (r = 0.60, p less than 0.001), body mass index (r = 0.32, p less than 0.05) and Apolipoprotein B (r = 0.33, p less than 0.05). The two latter correlations disappeared after adjustment for insulin. These results are in agreement with our previous report showing an in vitro effect of insulin on the synthesis of PAI by a hepatocellular cell line. Hyperinsulinemia presented by type 2 diabetic patients may increase the hepatic synthesis of PAI, inducing an hypofibrinolysis, which could play a role in the development of the vascular complications. Attempts to reduce hyperinsulinemia could have a favorable effect by lowering PAI activity.

Effect of 24 hours of normoglycaemia on tissue-type plasminogen activator plasma levels in insulin-dependent diabetes.

We have previously demonstrated that a short period of normoglycaemia obtained through an artificial pancreas in uncontrolled insulin-dependent diabetics improves parameters of the functional microangiopathy such as erythrocyte deformability and platelet aggregation. Because recently an immunoradiometric assay for tissue plasminogen activator (t-PA) was developed we measured t-PA levels in 18 uncontrolled insulin-dependent diabetics before and after 24 hr of normoglycaemia induced by insulin to look for a modification of endothelial cells function. After 24 hr of strict control, plasma free insulin levels rose significantly, total t-PA R-Ag, its active fibrin binding fraction and euglobulin fibrinolytic activity were significantly decreased. These results suggest a responsibility for insulin in the decrease in t-PA blood level and could explain at least partially the relation between hyperinsulinism, thrombosis and atherogenesis.