Hyperinsulinemia. A link between hypertension obesity and glucose intolerance

Role of aldosterone and angiotensin II in insulin resistance: an update

The role of the Renin-Angiotensin-Aldosterone system (RAAS) on the development of insulin resistance and cardiovascular disease is an area of growing interest. Most of the deleterious actions of the RAAS on insulin sensitivity appear to be mediated through activation of the Angiotensin II (Ang II) Receptor type 1 (AT(1)R) and increased production of mineralocorticoids. The underlying mechanisms leading to impaired insulin sensitivity remain to be fully elucidated, but involve increased production of reactive oxygen species and oxidative stress. Both experimental and clinical studies also implicate aldosterone in the development of insulin resistance, hypertension, endothelial dysfunction, cardiovascular tissue fibrosis, remodelling, inflammation and oxidative stress. There is abundant evidence linking aldosterone, through non-genomic actions, to defective intracellular insulin signalling, impaired glucose homeostasis and systemic insulin resistance not only in skeletal muscle and liver but also in cardiovascular tissue. Blockade of the different components of the RAAS, in particular Ang II and AT(1)R, results in attenuation of insulin resistance, glucose homeostasis, as well as decreased cardiovascular disease morbidity and mortality. These beneficial effects go beyond to those expected with isolated control of hypertension. This review focuses on the role of Ang II and aldosterone in the pathogenesis of insulin resistance, as well as in clinical relevance of RAAS blockade in the prevention and treatment of the metabolic syndrome and cardiovascular disease.

Conjugated linoleic acid supplementation enhances antihypertensive effect of ramipril in Chinese patients with obesity-related hypertension

BACKGROUND

Conjugated linoleic acid (CLA) refers to a group of positional and geometrical conjugated dienoic isomers of linoleic acid. Our aim was to investigate the effect of 8-week dietary CLA supplementation on blood pressure, concentrations of plasma adiponecin, leptin, and as well as angiotensin-converting enzyme (ACE) activity in obese hypertensive subjects.

METHODS

Eighty obese individuals with stage 1 uncontrolled essential hypertension were randomized in a double-blind, placebo-controlled trial. Participants were randomized to a daily dose of 4.5 g/day CLA (nine 0.5-g capsules; a 50:50 isomer blend of c 9,t 11 and t 10,c 12 CLA) with 37.5 mg/day ramipril (group 1) or placebo with 37.5 mg/day ramipril (group 2) for 8 weeks. Baseline and endpoint systolic BP, diastolic BP, and concentrations of plasma adiponecin, leptin, angiotensinogen, and ACE activity were measured.

RESULTS

Treatment with CLA significantly enhanced the reduction effect of ramipril on systolic BP and diastolic BP (P < 0.05). It also increased plasma adiponectin concentration (P < 0.05) and decreased plasma concentrations of leptin and angiotensinogen (P < 0.05); however, significant change was not observed in ACE activity.

CONCLUSIONS

An 8-week long supplementation of CLA enhanced the effect of ramipril on blood pressure reduction in treated obese hypertensive patients. The antihypertensive effect of CLA might be related to the changed secretion of hypertensive adipocytokines in plasma.

Relevance of hemostatic risk factors on coronary morphology in patients with diabetes mellitus type 2

Objective

The influence hemostatitc parameters on the morphological extent and severity of coronary artery disease were studied in patients with and without DM type 2.

Background

It is known that patients with diabetes (DM) have abnormal metabolic and hemostatic parameters

Methods

Of 150 consecutive patients with angiographically proven coronary artery disease 29 presented with DM. Additionally to parameters of lipid-metabolism fibrinogen, tissue-plasminogenactivator (t-PA), plasminogen-activator-inhibitor (PAI), plasmin-a-antiplasmin (PAP), prothrombin-fragment 1+2 (F1+2), thrombin-antithrombin (TAT), von-willebrand-factor (vWF), platelet factor 4 (PF4), glykomembranproteine 140 (GMP140) and the rheologic parameters plasma viscosity and red blood cell aggregation were evaluated. The extent and severity of CAD was evaluated according to the criteria of the American Heart Association.

Results

Patients with DM presented with a higher number of conventional risk factors as compared to non-diabetic patients. Additionally there were significant differences for F1+2, red blood cell aggregation and PAI. Diabetic patients showed a more severe extent of coronary arteriosclerosis, which also could be found more distally. A significant relationship between blood-glucose, thrombocyte-activation (vWF), endogenous fibrinolysis (PAI) and the severity of CAD and a more distal location of stenoses could be found (r = 0.6, p < 0.001).

Conclusion

Patients with coronary artery disease and DM type 2 showed marked alterations of metabolic, hemostatic, fibrinolytic and rheologic parameters, which can produce a prothrombogenic state. A direct association of thrombogenic factors on coronary morphology could be shown. This can be the pathophysiologic mechanism of more severe and distal pronounced coronary atherosclerosis in these patients.

Coingestion of acylglycerols differentially affects glucose-induced insulin secretion via glucose-dependent insulinotropic polypeptide in C57BL/6J mice

The precise role of fat in postprandial glycemia and insulinemia has not been thoroughly researched because postprandial blood glucose and concurrent insulin secretion are largely assumed to be proportional to carbohydrate intake. Recent studies have suggested that dietary fat differentially regulates the postprandial insulin response. To explore this, we examined the effects of coadministered fat on glucose-induced glycemia and insulinemia in C57BL/6J mice. The insulin response to glucose was augmented by the addition of glycerol trioleate (TO) in a dose-dependent manner, which was associated with enhanced glucose transport from the circulation to muscle and adipose tissues. To investigate the mechanism underlying fat-induced hyperinsulinemia, we examined the release of the incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1. TO increased GIP secretion, whereas glucagon-like peptide-1 secretion was unaffected. TO-induced hyperinsulinemia was significantly attenuated by the pretreatment of mice with a specific GIP antagonist. Diacylglycerol (DAG) promoted lower postprandial GIP and triglyceride responses and, when ingested with glucose, a lower insulin response compared with triacylglycerol of a similar fatty acid composition. Pluronic L-81, an inhibitor of chylomicron formation, reduced not only the triglyceride response but also TO-induced GIP secretion, indicating that the lower GIP response after DAG ingestion may be associated with retarded chylomicron formation in the small intestine. We conclude that dietary fat augments glucose-induced insulinemia via gut-derived GIP and, thereby, influences postprandial nutrient metabolism in mice. DAG promotes a lower GIP and thereby reduced insulin responses compared with triacylglycerol, which may differentially influence postprandial energy homeostasis.

Indices of mineral metabolism in relation to blood pressure in a sample of a healthy population

Indices of mineral metabolism in blood and urine were analysed in relation to blood pressure in 97 healthy subjects aged 16-82 years. In a multivariate analysis, after allowing for the effects of sex, body mass index (BMI) and age, there was an inverse relationship between plasma level of ionized calcium and mean blood pressure (MBP) (beta = -50.0 mmHg/mmol/l P-ionized calcium, p = 0.0005). In univariate analyses MBP also showed statistically significant inverse relationships with plasma ionized calcium, serum phosphate and renal threshold concentration of phosphate; positive relationships to MBP were found for fasting urinary excretion of calcium and cyclic adenosine monophosphate. However, when examined multivariately, only the relation between MBP and plasma ionized calcium persisted. This study supports previous findings of an inverse relationship between blood pressure and serum ionized calcium and extends the observations to the physiological range. It is further evident from this study that BMI and age should be taken into account in analyses of the relationship between blood pressure and mineral metabolism.

Decreased skeletal muscle potassium in obesity

The effect of body weight on total body potassium, skeletal muscle electrolytes and fat content was studied in seven lean and seven obese middle-aged men and seven lean and eight obese middle-aged women. Total body potassium and total body fat increased with body weight (p less than 0.01 and less than 0.05 for men, and p less than 0.05 and p less than 0.001 for women, respectively). So did muscle fat in men (p less than 0.01), while muscle tissue potassium was decreased in both obese men (p less than 0.001) and obese women (p less than 0.05). The skeletal muscle Na/K-ratio tended to be higher in obese men (p less than 0.1) but was not related to body weight in women. Skeletal muscle magnesium was higher (p less than 0.01) in obese men than in lean men. No differences between lean and obese women were found. Obese men had higher diastolic blood pressure (p less than 0.05) than lean men, while there was no difference between obese and lean women. Compared with lean subjects, obese subjects thus had lower relative skeletal muscle mass and men, especially, had more fat and less potassium in the skeletal muscle.

The associations between obesity, adipose tissue distribution and disease

Recent research has shown the marked differences in association with disease between obesity localized to the abdominal respectively to the gluteal-femoral regions. In this review systematic analyses were performed of the associations between obesity (body mass index, BMI) or abdominal obesity (increased waist-over-hip circumference ratio, WHR) on the one hand, and a number of disease end points, and their risk factors, as well as other factors on the other, WHR was associated with cardiovascular disease, premature death, stroke, non-insulin-dependent diabetes mellitus and female carcinomas. In contrast, BMI tended to be negatively correlated to cardiovascular disease, premature death, and stroke, but positively to diabetes. The established risk factors for these end points were found to correlate to WHR, while this was often not the case with BMI. BMI was positively correlated only to insulin, triglycerides and blood pressure. Together with diabetes mellitus, this seems to constitute a metabolic group of conditions which are thus associated with BMI. Androgens (in women), and perhaps cortisol, seem to be positively, and progesterone negatively correlated to WHR. The WHR was also positively associated with sick leave, several psychological maladjustments, psychosomatic and psychiatric disease. Attempts were made to interpret these findings. In a first alternative an elevation of FFA concentration, produced from abdominal adipose tissue, was considered to be the trigger factor for the pathologic aberrations associated with abdominal distribution of body fat. When obesity is added, the metabolic aberrations may be exaggerated. In a second alternative adrenal cortex hyperactivity was tested as the cause. When combined with the FFA hypothesis, this might explain many but not all of the findings. It seems possible to produce an almost identical syndrome in primates by defined experimental stress. Women with high WHR were found to have a number of symptoms of poor coping to stress. It was therefore suggested that part of the background to this syndrome might be a hypothalamic arousal syndrome developing with stress. It was concluded that obesity and abdominal distribution of adipose tissue constitute two separate entities with different pathogenesis, clinical consequences and probably treatment.

The insulin gradient phenomenon: a manifestation of the effects of body weight on blood pressure and insulin resistance

The relationship between hyperinsulinemia and hypertension is frequently observed in overweight patients; however, population studies have not confirmed an independent association. A population study was conducted to assess whether differences in body mass index and levels of insulinemia modify cardiovascular hemodynamics and arterial pressure. In all, 322 healthy adults underwent a medical evaluation including insulin sensitivity and cardiac performance assessment with echocardiography. A direct relationship between body mass index and blood pressure (r=0.36; P<.01) was shown along with increments in fasting insulin levels. The underlying and progressive rise in insulin levels during blood pressure increase is named the insulin gradient. Left ventricular systolic indexes were significantly greater in the higher-insulin quartile. These findings suggest that body weight increases accompany a rise in systolic pressure and a drop in insulin sensitivity related to the insulin gradient. Increments in ejection fraction and cardiac output with normal total peripheral resistance are related to the blood pressure shift in these persons.

Causes and mechanisms of nondipping hypertension

Growing evidence indicates that nondippers have worsened cardiovascular outcomes than dippers. Ambulatory blood pressure monitoring with a lack of nocturnal BP fall (nondipping) have also been shown to be more closely associated with target organ damage and worsened cardiovascular outcome than in patients with essential hypertension with dipping pattern. The underlying pathogenetic mechanisms potentially linking nondipping with cardiovascular disease are not fully understood. There are multiple possible underlying pathophysiologic mechanisms in the impaired BP decline during the night. Extrinsic and intrinsic factors including abnormal neurohormonal regulation, lack of physical activity, nutritional factors such as increased dietary sodium intake, and smoking of tobacco have been implicated for blunted circadian rhythm of BP. Certain diseases such as diabetes and chronic renal diseases also affect the circadian BP rhythm. Currently, the clinical importance of nondipping is known well; however, the relationship between certain disease states and nondipping has not been fully explained yet. This paper will attempt to address to clarify the underlying basis for nondipping and the specific associations with various disease states.

Undetected type 2 diabetes in older adults

BACKGROUND

early detection and prompt treatment of type 2 diabetes mellitus (T2D) may reduce the complications and burden associated with the disease.

OBJECTIVE

to evaluate the rate of undetected T2D (UT2D) among older adults who were screened 25 years ago, identify the characteristics of UT2D patients and suggest a high-risk profile most suitable for screening.

METHODS

a cross-sectional study of a group of 623 older adult survivors of 25-year cohort, 53.5% males, aged 58- 93 years in a personal interview on lifestyle habits, morbidity and medication use. Self-administered measurement of subjective health perception. Anthropometric measurements, laboratory examinations of 12-h fasting venous blood and 2-h oral glucose tolerance tests were carried out.

RESULTS

the prevalence of previously diagnosed diabetes was 18.9% and of UT2D 13.2%. The likelihood of having UT2D was higher for males, those with systolic blood pressure >or=130 mmHg, triglycerides >or=1.7 mmol/l (150 mg/dl) and large waist circumference; all are components of the metabolic syndrome. Compared to known diabetic patients, the undetected were predominantly males, slightly younger, rated their health status more favourably and had less comorbidities.

CONCLUSION

a large proportion of older adults with T2D were undiagnosed. Screening efforts for T2D should address those exhibiting characteristics of the metabolic syndrome in a seemingly healthy population of older adults.

Abdominal obesity is associated with potassium depletion and changes in glucose homeostasis during diuretic therapy

The activation of the renin-angiotensin system (RAS) is an important mechanism that contributes to hypertension in obese individuals. Thiazide diuretics also activate the RAS in response to volume contraction and can lead to a decrease in serum potassium values and glucose metabolism abnormalities. To evaluate the impact of abdominal obesity on potassium depletion and glucose homeostasis in hypertensive patients receiving thiazide therapy, the authors studied 329 hypertensive patients without known diabetes or impaired renal function. Patients were stratified into 2 major groups according to whether they used thiazide diuretic therapy, and each group was further divided in 2 subgroups according to the presence of abdominal obesity. The authors demonstrated that obese patients receiving diuretic therapy had lower plasma potassium levels and higher glucose values compared with nonobese patients receiving diuretic therapy. In conclusion, abdominal obesity predisposes to potassium depletion during diuretic therapy in association with effects on glucose homeostasis.

Hyperinsulinemia and insulin resistance are independently associated with plasma lipids, uric acid and blood pressure in non-diabetic subjects. The GISIR database

BACKGROUND AND AIMS

We evaluated whether hyperinsulinemia and/or insulin resistance are independently associated with plasma lipids, uric acid and blood pressure in non-diabetic subjects.

METHODS AND RESULTS

A database of non-diabetic Italian subjects has recently been set up using data from hyperinsulinemic euglycemic clamp studies carried out using the standard technique (40 mU per min per square meter of body surface area). In this database we evaluated the relationships between fasting plasma insulin (FPI), glucose metabolized during clamp (M) and plasma levels of triglycerides (TG), high density lipoprotein cholesterol (HDL-C), uric acid (UA) as well as blood pressure (BP) in non-diabetic subjects with fasting plasma glucose <6.1 mmol/l. Parallel analyses were conducted in all subjects in the database (n=1093) and in those with all variables available (n=309). In the univariate analysis both FPI and M were significantly correlated with TG, HDL-C, UA and BP (systolic, diastolic and mean). Multivariate regression analyses including center, sex, age, body mass index (BMI), FPI and M as independent variables showed that: (1) TG and UA were positively correlated with FPI and negatively correlated with M; (2) HDL-C was negatively correlated with FPI and positively correlated with M; and (3) BP was negatively correlated with both FPI and M. Analyses of covariance showed that, after adjusting for center, sex, age and BMI, subjects with isolated hyperinsulinemia or isolated insulin resistance had higher TG and UA and lower HDL-C. Subjects with isolated insulin resistance had also higher BP whereas subjects with isolated hyperinsulinemia had lower BP. Subjects with both defects had a worse profile.

CONCLUSIONS

Hyperinsulinemia and insulin resistance might contribute with distinct and independent mechanisms to the development of several metabolic and hemodynamic disorders often clustering in the same individual. In particular, hypertriglyceridemia, low HDL-cholesterol and hyperuricemia seem to be related to both hyperinsulinemia and insulin resistance, whereas hypertension seems to be related only to insulin resistance.

Hypertension in obesity

Hypertension and obesity are major components of the cardiometabolic syndrome and are both on the rise worldwide, with enormous consequences on global health and the economy. The relationship between hypertension and obesity is multifaceted; the etiology is complex and it is not well elucidated. This article, reviews the current knowledge on obesity-related hypertension. Further understanding of the underlying mechanisms of this epidemic will be important in devising future treatment avenues.

Boc5, a non-peptidic glucagon-like Peptide-1 receptor agonist, invokes sustained glycemic control and weight loss in diabetic mice

Background

Our recent discovery of the substituted cyclobutane Boc5, one of the first non-peptidic agonists at glucagon-like peptide-1 receptors, offers the potential of combining oral availability with full agonism capable of eliciting antidiabetic and antiobesity effects. The present study was aimed at determining the in vivo pharmacologic properties of Boc5 in both normal and diabetic mice following chronic administration, with emphasis on glycemic control and weight loss.

Methodology/Principal Findings

C57BL/6J and db/db mice were treated daily with Boc5 for 4 weeks and a range of pharmacologic parameters, including hemoglobin A1c, intraperitoneal glucose tolerance, insulin tolerance, fasting insulin and leptin levels, food intake, body weight and fat mass, were assessed before and after the treatment. Effects on food intake, gastric emptying, and insulinogenic index were also investigated in animals acutely administered with Boc5. Boc5 (3 mg) was able to induce a durable restoration of glycemic control (normalization of both hemoglobin A1c and intraperitoneal glucose tolerance) in db/db mice, following 4 weeks of daily administration. As with peptidic glucagon-like peptide-1 receptor agonists, its glycemic benefit and weight (fat) loss were associated with dose-dependent effects that included reduction in food intake, slowing of gastric emptying (both of which reduce nutrient-drive at β-cells), stimulation of insulin secretion (which was glucose-dependent), and elevation in insulin sensitivity. There was little effect on normal mice treated in the same manner.

Conclusions/Significance

Our findings suggest that Boc5 is the only non-peptidic molecule reported thus far to simultaneously activate this spectrum of antidiabetic effects.

Coronary endothelial dysfunction and impaired microcirculation response to atrial natriuretic peptide in hyperinsulinemia

Endothelial dysfunction occurs in hyperinsulinemia (HI). Coronary microcirculation responses to vasoactive agents are examined in 57 patients with angiographically normal coronary arteries. Patients were divided into 2 groups, 37 with normoinsulinemia (NI) and 20 with HI based on results of a 75-g oral glucose tolerance test. Epicardial artery vasoactivity in response to acetylcholine chloride is measured to assess endothelial function. Coronary microcirculation function is evaluated by intracoronary administration of 50 microg of adenosine triphosphate, 1 mg of isosorbide dinitrate, and 0.05 mg/kg of atrial natriuretic peptide. Epicardial artery vasoconstriction in response to 100 microg of acetylcholine is mildly reduced in HI (P = .04). Coronary flow reserve in response to adenosine triphosphate in NI is similar to that in HI. In NI, the resting mean (SD) peak velocity in response to isosorbide dinitrate (40.7 [10.9] cm/s) vs atrial natriuretic peptide (39.6 [10.9] cm/s) is similar. In contrast, the resting mean (SD) peak velocity in response to atrial natriuretic peptide (31.3 [9.3] cm/s) vs isosorbide dinitrate (43.5 [10.0] cm/s) in HI is statistically significantly blunted (P < .001). Atrial natriuretic peptide may have a pathologic effect on coronary microcirculation even in mild endothelial dysfunction among patients with HI.

The metabolic syndrome and the heart--a considered opinion

The metabolic syndrome (MS) is a multifactorial, heterogeneous group of risk factors for the development of cardiovascular disease. Here we review the evidence in support of the hypothesis that metabolic dysregulation of the body as a whole leads to contractile dysfunction of the heart due to an imbalance of substrate uptake (increased) and substrate oxidation (decreased). The consequences of this imbalance were already recognized 150 years ago by Virchow when he described "fatty atrophy" of the heart as a "true metamorphosis of the heart muscle cell."

Long-term effects of intracerebroventricular insulin microinjection on renal sodium handling and arterial blood pressure in rats

The role of the central nervous system (CNS) in the control of hydrosaline homeostasis has been strikingly demonstrated by several studies. Our laboratory recently showed that centrally administered insulin produced a dose-related increase in the urinary output of sodium, which was abolished by bilateral renal denervation, nitric oxide synthase inhibition and cerebroventricular streptozotocin administration in rats. Recent studies have shown that hyperinsulinemia induces subtle derangements of intracellular insulin-insulin receptor trafficking and insulin metabolism, which are associated with an impairment of insulin signaling. The long-term effect of high insulin levels on the periventricular region could alter insulin signaling, which in turn, may modify the central natriuretic and cardiovascular effects of this peptide. In order to evaluate this hypothesis, we investigated the effects of 7-day i.c.v. insulin administration on tubular handling and blood pressure in conscious, unrestrained rats and their controls, randomly assigned to one of two separate groups: (a) i.c.v. 0.15M NaCl-injected (n=7) and (b) i.c.v. 126.0 ng insulin-injected rats (n=7). In the current study, there were no significant differences between the blood pressure, daily tap water intake and serum sodium, potassium, lithium and creatinine levels in control i.c.v. 0.15M NaCl-injected rats, compared with the insulin-treated group. Conversely, there was a significant decrease in the daily solid rat chow intake (Co: 16.4+/-3.5 g vs. Ins: 10.3+/-2.6g, P=0.003) in 7-day long-term insulin-treated rats, compared with the control group. We confirmed that centrally administered insulin produced a substantial increase in the urinary output of Na+, Li+ and K+, and that the response was significantly enhanced in long-term i.c.v. insulin pre-treated animals, when compared with controls (fractional sodium excretion (FE(Na)) from basal: 0.047+/-0.18% to Ins-treated: 0.111+/-0.035%, P=0.001). Additionally, we demonstrated that insulin-induced natriuresis occurred by increasing fractional proximal (FEP(Na)) from basal (16.8+/-2.6% to Ins-treated: 26.7+/-2.8%, P=0.001) and post-proximal sodium excretion (FEPP(Na)) from basal (0.37+/-0.03% to Ins-treated: 0.42+/-0.05%, P=0.043), despite a decreased Na(+) filtered load and rat food intake. The current data suggest that centrally injected insulin maintain its CNS ability to amplify neuronal hypotensive and natriuretic pathways that counteract the known peripheral antinatriuretic effects of insulin.

Nocturnal blood pressure fall and metabolic syndrome score in hypertensive patients

BACKGROUND

Data relating dipping status to metabolic syndrome (MS) scores are not available. The purpose of this study is to investigate any possible association of different dipping patterns to MS scores in untreated patients with essential hypertension.

METHODS

The study included 6256 consecutive, treatment-naive patients with essential hypertension who attended our outpatient clinics. All underwent repeated office blood pressure measurements, 24-h ambulatory blood pressure monitoring, and full clinical and laboratory evaluation. The diagnosis of MS was made according to the Adult Treatment Panel III criteria and patients were classified into five groups: group I (hypertension), group II (hypertension+any one component), group III (hypertension+any two components), group IV (hypertension+any three components), and group V (all five components). Dipping pattern was defined as 'dippers' with nocturnal systolic blood pressure (NSBP) falling >or=10 but <20%, 'nondippers' with NSBP falling >or=0% but <10%, 'extreme dippers' with NSBP falling >or=20%, and 'reverse dippers' with NSBP increasing.

RESULTS

Hypertensive patients with MS (n=2573) had higher clinical and ambulatory blood pressure values (P<0.001), whereas the dominant dipping pattern in the non-MS group was nondippers (47.6%), and in the MS group, extreme dippers (37.8%). Furthermore, a considerable decrease in the prevalence of dippers was noticed with the increasing number of MS components (21.1 vs. 19.2 vs. 14.5 vs. 8.4 vs. 7.2%, P<0.001). In contrast, a significant rise in the prevalence of reverse dippers was observed with the increasing number of MS components (7.4 vs. 10.1 vs. 14.9 vs. 20.4 vs. 31.2%, P<0.001).

CONCLUSIONS

It seems that hypertensive patients have an increased prevalence of abnormal dipping patterns as the number of MS components rises.

Expression of subcutaneous adipose tissue phosphoenolpyruvate carboxykinase correlates with body mass index in nondiabetic women

Phosphoenolpyruvate carboxykinase (PEPCK) is a key enzyme for glyceroneogenesis in adipose tissues. Dysregulated glyceroneogenesis is associated with abnormal fatty acid homeostasis, obesity, and insulin resistance in both animal and cellular studies. However, the role of PEPCK expression in human adipose tissues on metabolic phenotypes has not been explored. This study aimed to analyze the correlation between PEPCK messenger RNA (mRNA) expressions in the subcutaneous adipose tissues with obesity-related metabolic phenotypes. We obtained the demographic data, biochemical variables, and abdominal subcutaneous adipose tissue from 75 nondiabetic nonmenopausal women. The relative PEPCK mRNA levels were quantified by real-time polymerase chain reaction normalized with beta-actin as a control. The PEPCK mRNA levels of subcutaneous tissue were positively correlated with body mass index (BMI) using either univariate (r = 0.413, P < .001) or multivariate linear regression analysis (beta = .978 +/- .239, P < .001). The mRNA expression of PEPCK was also positively correlated with body fat percentage (r = 0.436, P < .001), plasma triacylglycerol, and total cholesterol levels (both P values < .001). However, the significant correlation between lipid profile and PEPCK expression in subcutaneous tissue was abolished after adjusting for BMI. The relative subcutaneous PEPCK mRNA level was not correlated with fasting plasma glucose and insulin, and with an insulin resistance index measured with homeostasis model assessment. In conclusion, we showed that PEPCK mRNA expression in the subcutaneous adipose tissues was associated with BMI and plasma triacylglycerol and total cholesterol levels, but was not correlated with insulin resistance index.

Pioglitazone opposes neurogenic vascular dysfunction associated with chronic hyperinsulinaemia

BACKGROUND AND PURPOSE

We previously demonstrated that chronic hyperinsulinaemia induced by drinking high levels of fructose augments adrenergic nerve-mediated vasoconstriction and suppresses vasodilatation mediated by calcitonin gene-related peptide (CGRP)-containing (CGRPergic) vasodilator nerves. In this study, the effects of pioglitazone on vascular responses induced by stimulation of adrenergic nerves, CGRPergic nerves and vasoactive agents were investigated in pithed rats given 15% fructose solution to drink (FDR).

EXPERIMENTAL APPROACH

To assess the effect of pioglitazone on the altered vascular responsiveness in the hyperinsulinaemic state in vivo, changes in vascular responses to spinal cord stimulation (SCS) and intravenous bolus injections of noradrenaline, angiotensin II and CGRP were evaluated in pithed control rats and FDR either untreated or treated with pioglitazone.

KEY RESULTS

In the pithed FDR, vasoconstrictor responses to SCS and to injections of noradrenaline and angiotensin II were significantly greater than those of pithed control rats. In pithed FDR with artificially increased blood pressure and blockade of the autonomic ganglia, the vasodilator responses to SCS and CGRP injection were significantly smaller than those of pithed control rats. Oral administration of pioglitazone to FDR for two weeks markedly decreased plasma levels of insulin, triglycerides and blood glucose. In FDR pioglitazone diminished the augmented vasoconstrictor responses to SCS, noradrenaline and angiotensin II, and ameliorated the decrease in vasodilator responses to SCS.

CONCLUSIONS AND IMPLICATIONS

The present results suggest that pioglitazone improves not only insulin resistance, but also the dysfunctions in vascular control regulated by adrenergic and CGRPergic nerves in the hyperinsulinaemic state.

Insulin resistance and hyperinsulinemia: is hyperinsulinemia the cart or the horse?

Insulin resistance, recently recognized as a strong predictor of disease in adults, has become the leading element of the metabolic syndrome and renewed as a focus of research. The condition exists when insulin levels are higher than expected relative to the level of glucose. Thus, insulin resistance is by definition tethered to hyperinsulinemia. The rising prevalence of medical conditions where insulin resistance is common has energized research into the causes. Many causes and consequences have been identified, but the direct contributions of insulin itself in causing or sustaining insulin resistance have received little sustained attention. We examine situations where insulin itself appears to be a proximate and important quantitative contributor to insulin resistance. 1) Mice transfected with extra copies of the insulin gene produce basal and stimulated insulin levels that are two to four times elevated. The mice are of normal weight but show insulin resistance, hyperglycemia, and hypertriglyceridemia. 2) Somogyi described patients with unusually high doses of insulin and hyperglycemia. Episodes of hypoglycemia with release of glucose-raising hormones, postulated as the culprits in early studies, have largely been excluded by studies including continuous glucose monitoring. 3) Rats and humans treated with escalating doses of insulin show both hyperinsulinemia and insulin resistance. 4) The pulsatile administration of insulin (rather than continuous) results in reduced requirements for insulin. 5) Many patients with insulinoma who have elevated basal levels of insulin have reduced (but not absent) responsiveness to administered insulin. In summary, hyperinsulinemia is often both a result and a driver of insulin resistance.

Coronary heart disease in individuals with spinal cord injury: assessment of risk factors

STUDY DESIGN

Discussion document.

OBJECTIVES/METHOD

To review the work performed on conditions and disorders that predispose persons with spinal cord injury (SCI) to an increased risk of coronary heart disease (CHD).

RESULTS/DISCUSSION

Individuals with SCI have an increased prevalence of abnormalities in carbohydrate and lipid metabolism because of immobilization, muscle atrophy and relative adiposity. In those with SCI, an inverse relationship has been reported between serum high-density lipoprotein (HDL) cholesterol values and abdominal circumference, and a direct relationship between serum triglycerides levels and abdominal circumference. Persons with SCI have lower serum HDL cholesterol levels than able-bodied controls. A higher prevalence of insulin resistance and diabetes mellitus, as well as an earlier occurrence of coronary heart disease (CHD), has been reported in persons with SCI than in the general population. Recently, a higher prevalence and greater degree of coronary artery calcification by electron beam computerized tomography has been demonstrated in persons with SCI, even if matched with the able-bodied population for age, gender, ethnicity and conventional risk factors for CHD. Knowledge of relative risk of CHD in persons with SCI is important for appropriate intervention strategies. The conventional risk factors for CHD were determined in veterans with SCI to assign risk to determine target low-density lipoprotein cholesterol levels for therapeutic intervention. Limitations of conventional guidelines when applied to the SCI population should be appreciated. Conventional risk factors for CHD should be identified and treated in individuals with SCI, according to current standards of care.

Insulin sensitivity as a risk factor for common carotid intima media thickness (IMT): its relation to atherosclerosis

INTRODUCTION

The relationship between insulin resistance and atherosclerosis (ATH) in non-diabetic hypertensive patients from the Asian Indian population remains poorly understood. To resolve this issue, the present study was designed to analyze whether insulin sensitivity in a non-diabetic individual is related to the development of ATH.(by using IMT as an index) and whether this relationship is dependent on the presence of other cardiovascular disease (CVD) risk factors such as dyslipidemia and hypertension.

METHODOLOGY

This study included 68 healthy controls with no diabetes and hypertension and 41 hypertensive patients who underwent four-point oral glucose tolerance test (OGTT) and intravenous glucose tolerance test (IVGTT). A biochemical profile, beta mode ultrasonography for intima media thickness of carotid artery, and ECG determination was carried out.

RESULTS

Hypertensive patients in our study exhibited significantly increased abdominal obesity. Blood pressure, fasting and 2 hr plasma glucose (4.62 +/- 0.08 and 5.55 +/- 0.17 mmol/l), and triglyceride (1.47 +/- 0.067 mmol/l) levels were compared to those of control subjects (p < 0.05). The fasting insulin levels and HOMA-IR were also significantly increased and Composite Insulin Sensitivity Index (CISI) reduced compared to controls with p < 0.01. Intima media thickness of the left (0.08 +/- 0.01) and right (0.069 +/- 0.008) CA were both significantly increased in hypertensives (p < 0.01). Correlation analysis showed that IMT of the left carotid artery was significantly associated with triglyceride levels (r = 0.813, p < 0.05) but not with insulin measures such as HOMA-IR and CISI.

CONCLUSION

Hyperinsulinemia was observed in our non-diabetic hypertensive patients, but no association was found between IMT and insulin resistance. That IMT of hypertensives was associated with triglyceride levels suggests that high levels of insulin may be related to the development of ATH indirectly through its effects on lipid metabolism in our population.

Physical activity is inversely associated with total homocysteine levels, independent of C677T MTHFR genotype and plasma B vitamins

The homocysteine level is considered to be a product of genetic and lifestyle interactions, mainly mutated methylenetetrahydrofolate reductase (MTHFR) and the intake of folate, vitamin B12 and pyridoxine, and their blood levels. Physical activity has been associated with lower homocysteine levels in some population studies, especially among elderly subjects. To further elucidate the observed association between homocysteine and physical activity, while accounting for the effect of the MTHFR C677T genotype, and of plasma levels of folate and B12 vitamins, a cross-sectional study of 620 males and females, aged 70.5 +/- 6.8 years, was carried out. Information on lifestyle habits was collected and laboratory examinations of 12-h fasting total plasma homocysteine, folate, and vitamin B12, as well as DNA analysis for MTHFR C677T variant, were performed. Median total homocysteine values were 11.4 micromol/l for males and 9.4 for females; p < 0.001. Smoking and ethnic origin were not found to be associated with homocysteine levels. Physically active subjects had significantly lower total homocysteine levels when adjusted for sex (p = 0.01). Significant inverse correlations were found between body mass index, plasma folate, B12 and homocysteine levels. Homocysteine levels of the CC, CT and TT genotypes were 9.7, 10.6 and 10.2 mumol/l, respectively (p = 0.002, controlling for sex). In a multiple linear regression model, a sedentary lifestyle increased homocysteine levels by 7% as compared to an active one (p = 0.03) controlling for sex, age, body mass index, folate, vitamin B12, and C677T genotype, all of which were also found to be significantly associated with homocysteine levels. Any level of physical activity was found to be independently associated with lower homocysteine levels in an elderly population, controlling for MTHFR genotype, plasma B-vitamins, age, sex, smoking and BMI. This study emphasizes the importance of maintaining a physically active lifestyle in the elderly.

A review of the metabolic syndrome

While the concept of this syndrome has been described more than 60 years ago, and more formally almost 20 years ago, the controversy continues as to its utility, which of the various syndrome definitions should be used and their ability to predict diabetes and/or cardiovascular disease. The metabolic syndrome, of cardiovascular risk factors, provides an early warning of at risk subjects and emphasises the need to treat more aggressively (by at least lifestyle modification) patients with multiple abnormalities even though the abnormalities might be slight. Further, the syndrome can be easily used in clinical practice and when it is assessed against the background of the patient's age, sex and smoking habits, it provides an evaluation of potential cardiovascular risk. Prospective intervention studies are the only means of definitively accepting or refuting the usefulness of the syndrome. The metabolic syndrome is an entity which merits attention from both the medical profession and public health authorities.

Effect of fatty acids on endothelium-dependent relaxation in the rabbit aorta

The metabolic syndrome, Type II (non-insulin-dependent) diabetes and obesity are associated with endothelial dysfunction and increased plasma concentrations of NEFAs (non-esterified fatty acids; free fatty acids). The present study was undertaken to define the inhibitory effects of saturated NEFAs on EDR (endothelium-dependent relaxation). Experiments were performed in rings of rabbit aorta to establish (i) dose-response relationships, (ii) the effect of chain length, (iii) the effect of the presence of double bonds, (iv) reversibility and time course of inhibition, and (v) the effect on nitric oxide production. Aortic rings were incubated (1 h) with NEFA-albumin complexes derived from lauric (C(12:0)), myristic (C(14:0)), palmitic (C(16:0)), stearic (C(18:0)) and linolenic (C(18:3)) acids. EDR induced by acetylcholine (0.1-10 mumol/l) was measured after pre-contraction with noradrenaline. Inhibition of EDR was dose-dependent (0.5-2 mmol/l NEFA), and the greatest inhibition (51%) was observed with stearic acid (2 mmol/l). Lauric acid had the smallest inhibitory effect. The inhibitory effects were always reversible and were evident after 15 min of incubation. Linolenic acid caused a significantly lower inhibition of EDR than stearic acid. SOD (superoxide dismutase) restored the inhibitory effect caused by NEFAs, suggesting the involvement of ROS (reactive oxygen species) in removing nitric oxide. The nitric oxide concentration measured after exposure of the rings to acetylcholine was lower after incubation with NEFAs than with Krebs buffer alone. This finding is consistent with removal of nitric oxide by ROS. This claim was supported by the demonstration of increased concentrations of nitrated tyrosine in the rings incubated with NEFAs.

Impact of body mass index on blood pressure levels in patients with polycystic ovary syndrome

As there is controversy about the prevalence of hypertension in patients with polycystic ovary syndrome (PCOS) and, up to the present moment, no studies have evaluated the impact of body mass index (BMI) on blood pressure levels (BP) in these patients, we studied retrospectively sixty-nine patients with PCOS, with BMI of 29.0 ± 6.7 kg/m² and aged 25.6 ± 5.6 yr, subdivided into three groups according to BMI (normal, overweight and obese) and evaluated regarding BP (mercury sphygmomanometer), basal hormonal profile, fasting glucose, and insulin sensitivity (HOMA-IR). Mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) were normal (118.1 ± 17.0 and 74.7 ± 11.5 mmHg, respectively), with a hypertension prevalence of 20.3%. Of these patients, 78.6% were obese and 21.4% were overweight. When the groups were compared according to BMI, a significant increase in SBP and DBP was observed (higher in overweight and obese patients for SBP and higher in obese for DBP), as well as a significant progressive increase in glucose, insulin, homeostatic model assessment, and a significant progressive decline in LH levels. When the patients were subdivided as normotensive or hypertensive, a significant difference was observed only for BMI (28.2 ± 6.1 and 34.7 ± 8.6 kg/m², respectively; p = 0.007). In conclusion, we observed a significant and progressive impact of BMI on blood pressure levels in our patients with polycystic ovary syndrome.

Predicting the 20-year diabetes incidence rate

BACKGROUND

The long-range prediction from clinical variables of the onset of diabetes is important to patients and clinicians. Our objective was to evaluate the efficacy of various glucose-related clinical measurements in predicting the 20-year risk of developing type 2 diabetes (T2DM) in an elderly population.

METHODS

In a prospective study, 672 men and women aged 59-92 years, who were not diabetic in 1980 and were part of a nationwide longitudinal randomized study, were followed-up in 2000-2003. Fasting glucose, 1- and 2-h post-oral glucose tolerance and insulin were measured in 1980 and 2000-2003.

RESULTS

A group of 174 (25.9%) survivors had progressed to diabetes during the 20-year follow-up. Fasting glucose values were a good predictor for diabetes. With the 100 mg/dL cut-off of impaired fasting glucose (IFG), a 2-4-times higher predictive sensitivity followed the dramatic increase in IFG prevalence compared to the 110 mg/dL cut-off, but at a cost of reduced specificity and positive predictive value (PPV). By receiver operating curve (ROC) analysis, a 1-h post-load glucose was similar to 2 h and fasting glucose in prediction of the 20-year incidence of diabetes, and classifying correctly the 77, 74 and 73% of the group, respectively. In adjusted logistic regressions, 2.28, 1.78 and 1.69-folds increased the 20-year risk, and were associated with each SD increment of the respective glucose values (p < 0.001).

CONCLUSIONS

Although the best population-based strategy for the diagnosis of T2DM would be the combination of fasting glucose followed by post-load glucose, for the purposes of long-term prediction of T2DM risk, fasting glucose is sufficient.

Insulin resistance and hyperinsulinemia are related to plasma aldosterone levels in hypertensive patients

OBJECTIVE

An association between aldosterone and insulin resistance has been demonstrated in obesity and primary aldosteronism and in blacks with the metabolic syndrome. The aim of this study was to evaluate the relationship of plasma aldosterone with insulin sensitivity in white subjects.

RESEARCH DESIGN AND METHODS

In 356 patients with essential hypertension and 102 normotensive control subjects of comparable age and BMI, we measured, after discontinuation of treatment, plasma active renin, aldosterone, cortisol, glucose, insulin, and C-peptide levels and calculated markers of insulin sensitivity. Direct assessment of insulin sensitivity was obtained in a subset of 64 hypertensive patients by a hyperinsulinemic clamp.

RESULTS

Hypertensive patients had significantly greater fasting plasma insulin and C-peptide concentrations and homeostasis model assessment (HOMA) indexes than normotensive control subjects. A positive association with increasing plasma aldosterone concentrations was demonstrated for plasma glucose, insulin, C-peptides, and HOMA. Assessment of insulin sensitivity by clamp showed a significant decrease of the metabolic clearance rate of glucose with increasing aldosterone levels. Significant correlations were found between plasma aldosterone, plasma insulin, and C-peptide levels, HOMA, and glucose metabolic clearance rate. Blood pressure and plasma potassium, plasma cortisol, and renin levels, but not BMI, were also directly correlated with plasma aldosterone. Multiple regression analysis showed that HOMA, together with plasma potassium, cortisol, and renin levels, was independently correlated with plasma aldosterone.

CONCLUSIONS

This study demonstrates a direct relationship between aldosterone, insulin resistance, and hyperinsulinemia in white subjects. In patients with hypertension, this relationship might contribute to maintenance of high blood pressure and increased cardiovascular risk.

Insulin resistance, hyperinsulinemia, and hypertension: an epidemiologic approach

During the past 2 decades, numerous experimental studies have provided solid evidence for the existence of several mechanisms connecting insulin resistance and hyperinsulinemia with blood pressure elevation, within the context of the cardiometabolic syndrome. In parallel, several groups have attempted to examine these associations from an epidemiologic perspective, but relevant findings were less consistent and not extensively discussed. Hyperinsulinemia has been associated with high blood pressure levels and hypertension development in cross-sectional, case-control, and prospective cohort studies. An association between insulin resistance and hypertension is also evident in existing studies, but prospective data on this relation are limited. Moreover, most of the evidence supporting close associations between these factors derives from Caucasian and Japanese populations, whereas data in other populations are not in agreement. This review summarizes and evaluates the relevant epidemiologic evidence to elucidate an important aspect of the relationship between hypertension and the cardiometabolic syndrome.

Gender differences in sympathetic nervous activity: influence of body mass and blood pressure

BACKGROUND

Obesity and high blood pressure (BP) commonly coexist in patients, and both conditions are associated with elevated sympathetic nervous activity. We tested whether the sympathetic nervous system was differently affected in men and women by the body mass index (BMI), BP, leptin and weight loss.

METHODS

We measured muscle sympathetic nerve activity (MSNA, microneurography), BP and plasma leptin concentrations in 167 age-matched normotensive and hypertensive men and women divided into three subgroups: lean, BMI < 25 kg/m; overweight, BMI > or = 25 and < 30 kg/m; and obese, BMI > or = 30 kg/m. These measurements were repeated in a subgroup of 19 obese subjects who underwent a 12-week diet.

RESULTS

Women with hypertension had increased MSNA compared with their normotensive counterparts (37 +/- 2 versus 25 +/- 2 bursts/min, analysis of variance, P < 0.001) and MSNA was significantly related to BP (P < 0.05, r = 0.236) but not to BMI. MSNA in men with hypertension was no different from that in normotensive subjects (33 +/- 2 versus 30 +/- 2 bursts/min), but MSNA was significantly related to BMI (P < 0.05, r = 0.249). Diet resulted in the same degree of weight loss in men and women, but induced a decrease in MSNA only in men (43 +/- 3 to 34 +/- 3 bursts/min, P < 0.01). The plasma leptin concentration was higher in women than in men, and for both groups it was related to BMI not BP (r = 0.497, P < 0.001 in women and r = 0.483, P < 0.001 in men).

CONCLUSION

These data demonstrate a gender difference in the regulation of the sympathetic nervous system, in which MSNA mainly relates to BP in women and to BMI in men.

Cardiovascular risk reduction in high-risk pediatric patients: a scientific statement from the American Heart Association Expert Panel on Population and Prevention Science; the Councils on Cardiovascular Disease in the Young, Epidemiology and Prevention, Nutrition, Physical Activity and Metabolism, High Blood Pressure Research, Cardiovascular Nursing, and the Kidney in Heart Disease; and the Interdisciplinary Working Group on Quality of Care and Outcomes Research

Although for most children the process of atherosclerosis is subclinical, dramatically accelerated atherosclerosis occurs in some pediatric disease states, with clinical coronary events occurring in childhood and very early adult life. As with most scientific statements about children and the future risk for cardiovascular disease, there are no randomized trials documenting the effects of risk reduction on hard clinical outcomes. A growing body of literature, however, identifies the importance of premature cardiovascular disease in the course of certain pediatric diagnoses and addresses the response to risk factor reduction. For this scientific statement, a panel of experts reviewed what is known about very premature cardiovascular disease in 8 high-risk pediatric diagnoses and, from the science base, developed practical recommendations for management of cardiovascular risk.

Pioglitazone decreases ambulatory blood pressure in type 2 diabetics with difficult-to-control hypertension

Blood pressure (BP) control at recently established goals of <130/80 mm Hg is often difficult to achieve in diabetic patients. This work examines the effect of pioglitazone on 24-hour ambulatory BP monitoring in patients with type 2 diabetes and difficult-to-control hypertension. Twenty-seven participants with difficult-to-control hypertension (defined as ambulatory BP monitoring >or=125/75 mm Hg) taking antihypertensive medications (mean, 4.1+/-0.8 drugs) were enrolled in an open, prospective, blinded end point study of add-on therapy with pioglitazone 30 to 45 mg for 20 weeks. After 20 weeks of treatment, 24-hour ambulatory BP monitoring showed significant reductions (from 144+/-13 to 136+/-16 mm Hg systolic BP and from 79+/-9 to 76+/-10 mm Hg diastolic BP [P=.001]). Treatment was also associated with improvements in insulin sensitivity and glycemic and lipid profile. These findings suggest that pioglitazone could be a therapeutic option in diabetics who still have elevated BP values in spite of receiving treatment with at least 3 antihypertensive drugs.

Animal and human tissue Na,K-ATPase in normal and insulin-resistant states: regulation, behaviour and interpretative hypothesis on NEFA effects

The sodium(Na)- and potassium(K)-activated adenosine-triphosphatase (Na,K-ATPase) is a membrane enzyme that energizes the Na-pump by hydrolysing adenosine triphosphate and wasting energy as heat, so playing a role in thermogenesis and energy balance. Na,K-ATPase regulation by insulin is controversial; in tissue of hyperglycemic-hyperinsulinemic ob/ob mice, we reported a reduction, whereas in streptozotocin-treated hypoinsulinemic-diabetic Swiss and ob/ob mice we found an increased activity, which is against a genetic defect and suggests a regulation by hyperinsulinemia. In human adipose tissue from obese patients, Na,K-ATPase activity was reduced and negatively correlated with body mass index, oral glucose tolerance test-insulinemic area and blood pressure. We hypothesized that obesity is associated with tissue Na,K-ATPase reduction, apparently linked to hyperinsulinemia, which may repress or inactivate the enzyme, thus opposing thyroid hormones and influencing thermogenesis and obesity development. Insulin action on Na,K-ATPase, in vivo, might be mediated by the high level of non-esterified fatty acids, which are circulating enzyme inhibitors and increase in obesity, diabetes and hypertension. In this paper, we analyse animal and human tissue Na,K-ATPase, its level, and its regulation and behaviour in some hyperinsulinemic and insulin-resistant states; moreover, we discuss the link of the enzyme with non-esterified fatty acids and attempt to interpret and organize in a coherent view the whole body of the exhaustive literature on this complicated topic.

Increased oxidative stress in prepubertal children born small for gestational age

CONTEXT

Low birth weight is associated with an increased risk of metabolic and cardiovascular diseases in adulthood. The development of insulin resistance (IR) seems to play a pivotal role; no data on the oxidant-antioxidant status are available in this risk group.

OBJECTIVE

This study is an assessment of oxidant-antioxidant status in prepubertal children born small for gestational age (SGA) in comparison to healthy controls and the relationship to IR.

DESIGN

This cross-sectional study compares indexes of IR and oxidant-antioxidant status in three different groups (SGA+, SGA-, controls), with analysis by post hoc and Pearson correlation.

SETTING

The study was conducted in the Academic Department of Pediatrics.

PARTICIPANTS

A total of 19 SGA+ and 16 SGA- children were compared with 13 controls.

INTERVENTION

No intervention was used.

MAIN OUTCOME MEASURES

Indexes of IR (glucose to insulin ratio, homeostasis model assessment of IR) were evaluated, and markers of oxidative stress (lag phase, malonildialdehyde, vitamin E) were measured.

RESULTS

Homeostasis model assessment of IR was significantly higher in SGA+ than SGA- children (1.32+/-0.9 vs. 0.69+/-0.47; P=0.03) and controls (0.71+/-0.37; P=0.04). Glucose to insulin ratio was significantly lower in SGA+ than SGA- children (12.41+/-5.01 vs. 26.54+/-17.18; P=0.02) and controls (26.96+/-20.70; P=0.04). Lag phase was significantly shorter in SGA+ than SGA- children (24.3+/-4.38 vs. 35.59+/-11.29 min; P=0.003) and controls (45.28+/-7.69 min; P=0.0001) and in SGA- than controls (P=0.01). Malonildialdehyde was significantly higher in SGA+ than SGA- children (0.79+/-0.3 vs. 0.6+/-0.1 nmol/mg; P=0.03) and controls (0.36+/-0.04 nmol/mg; P=0.0001) and in SGA- children than controls (P=0.02). Vitamin E was significantly reduced in SGA+ children than controls (27.54+/-7.9 vs. 43.23+/-11.32 micromol/liter; P=0.002).

CONCLUSION

Oxidative stress is present in both SGA+ and SGA- children, with a continuous alteration in relation to IR. Therefore, catch-up growth might exert the greatest influence in the development of future diseases.

The operative risk factors in the metabolic syndrome: is it lipids and high BP or are there direct vascular effects of insulin resistance and obesity

Increase in patients with central obesity and insulin resistance is an important cause for the worldwide increased incidence of type 2 diabetes. Several risk factors such as glucose intolerance, hyperinsulinemia, obesity, dyslipidemia, and hypertension, but also endothelial dysfunction and inflammation, have been found to cluster and often precede type 2 diabetes mellitus. Seeing the importance of early identification, the US National Cholesterol Education Program created a readily applicable definition of the metabolic syndrome for daily clinical practice. It is assumed that the cardiovascular risk for patients belonging to the metabolic syndrome can just be calculated out of the sum of the separate cardiovascular risk factors dyslipidemia and hypertension. However, there are also data pointing toward a higher risk than expected from these separate cardiovascular risk factors because of possible direct vascular effects of insulin resistance and obesity. Awareness of the underlying disorders of insulin resistance and its associated (non-) traditional risk factors such as endothelial dysfunction and inflammation is important for understanding the pathophysiology and thus coherent treatment.

Overweight, physical activity and high blood pressure in children: a review of the literature

Obesity is a growing problem in developed countries and is likely a major cause of the increased prevalence of high blood pressure in children. The aim of this review is to provide clinicians and clinical scientists with an overview of the current state of the literature describing the negative influence of obesity on blood pressure and it's determinants in children. In short, we discuss the array of vascular abnormalities seen in overweight children and adolescents, including endothelial dysfunction, arterial stiffening and insulin resistance. We also discuss the potential role of an increased activation of the sympathetic nervous system in the development of high blood pressure and vascular dysfunction associated with obesity. As there is little consensus regarding the methods to prevent or treat high blood pressure in children, we also provide a summary of the evidence supporting relationship between physical activity and blood pressure in children and adolescents. After reviewing a number of physical activity intervention studies performed in children, it appears as though 40 minutes of moderate to vigorous aerobic-based physical activity 3-5 days/week is required to improve vascular function and reduce blood pressure in obese children. Future studies should focus on describing the influence of physical activity on blood pressure control in overweight children.

Glycogen synthase kinase 3 inhibition improves insulin-stimulated glucose metabolism but not hypertension in high-fat-fed C57BL/6J mice

AIMS/HYPOTHESIS

In the current study, the effect of a highly specific peptide inhibitor of glycogen synthase kinase 3 (GSK3) (L803-mts) on glucose metabolism and BP was examined in a high-fat (HF) fed mouse model of diabetes.

METHODS

C57/BL6J mice were placed on an HF diet for 3 months and treated with L803-mts for 20 days, following which glucose metabolism was examined by euglycaemic-hyperinsulinaemic clamp studies. BP and heart rate were measured by radio-telemetry.

RESULTS

The HF mice were obese, with impaired glucose tolerance and high plasma insulin and leptin levels. L803-mts treatment significantly reduced the insulin levels and doubled the glucose infusion rate required to maintain a euglycaemic condition in the HF+L803-mts group compared with the HF group. Insulin failed to suppress the endogenous glucose production rate in the HF group while decreasing it by 75% in the HF+L803-mts group, accompanied by increased liver glycogen synthase activity and net hepatic glycogen synthesis. GSK3 inhibition also reduced peripheral insulin resistance. Plasma glucose disappearance rate increased by 60% in the HF+L803-mts group compared with the HF group. In addition, glucose uptake in heart and gastrocnemius muscle was markedly improved. Although mean arterial pressure increased following the HF diet, it did not change significantly during the 12 days of L803-mts treatment.

CONCLUSIONS/INTERPRETATION

These studies demonstrate that GSK3 inhibition improved hepatic and peripheral insulin resistance in a mouse model of HF-induced diabetes, but it failed to have an effect on BP. GSK3 may represent an important therapeutic target for insulin resistance.

The metabolic syndrome: metabolic changes with vascular consequences

Despite criticism regarding its clinical relevance, the concept of the metabolic syndrome improves our understanding of both the pathophysiology of insulin resistance and its associated metabolic changes and vascular consequences. Free fatty acids (FFA) and tumour necrosis factor-alpha (TNF-alpha) play prominent roles in the development of insulin resistance by impairing the intracellular insulin signalling transduction pathway. Obesity is an independent risk factor for cardiovascular disease and strongly related to insulin resistance. In case of obesity, FFAs and TNF-alpha are produced in abundance by adipocytes, whereas the production of adiponectin, an anti-inflammatory adipokine, is reduced. This imbalanced production of pro- and anti-inflammatory adipokines, as observed in adipocyte dysfunction, is thought to be the driving force behind insulin resistance. The role of several recently discovered adipokines such as resistin, visfatin and retinol-binding protein (RBP)-4 in the pathogenesis of insulin resistance is increasingly understood. Insulin resistance induces several metabolic changes, including hyperglycaemia, dyslipidaemia and hypertension, all leading to increased cardiovascular risk. In addition, the dysfunctional adipocyte, reflected largely by low adiponectin levels and a high TNF-alpha concentration, directly influences the vascular endothelium, causing endothelial dysfunction and atherosclerosis. Adipocyte dysfunction could therefore be regarded as the common antecedent of both insulin resistance and atherosclerosis and functions as the link between obesity and cardiovascular disease. Targeting the dysfunctional adipocyte may reduce the risk for both cardiovascular disease and the development of type 2 diabetes. Although lifestyle intervention remains the cornerstone of therapy in improving insulin sensitivity and its associated metabolic changes, medical treatment might prove to be important as well.

Cardiovascular Risk Reduction in High-Risk Pediatric Patients

Although for most children the process of atherosclerosis is subclinical, dramatically accelerated atherosclerosis occurs in some pediatric disease states, with clinical coronary events occurring in childhood and very early adult life. As with most scientific statements about children and the future risk for cardiovascular disease, there are no randomized trials documenting the effects of risk reduction on hard clinical outcomes. A growing body of literature, however, identifies the importance of premature cardiovascular disease in the course of certain pediatric diagnoses and addresses the response to risk factor reduction. For this scientific statement, a panel of experts reviewed what is known about very premature cardiovascular disease in 8 high-risk pediatric diagnoses and, from the science base, developed practical recommendations for management of cardiovascular risk.