Physiological and metabolic consequences of obesity

Elevated HbA1c levels in pre-Covid-19 infection increases the risk of mortality: A sistematic review and meta-analysis

AIMS

Diabetes is emerging as a risk factor for coronavirus disease (COVID)-19 prognosis. However, contradictory findings have been reported regarding the impact of glycaemic control on COVID-19 outcome. The aim of this meta-analysis was to explore the impact of hospital pre-admission or at-admission values of HbA1c on COVID-19 mortality or worsening in patients with diabetes.

MATERIALS AND METHODS

We searched PubMed, Embase and Scopus up to 30th December 2020. Eligibility criteria for study selection were the following: (1)enrolling patients with any form of diabetes mellitus and hospitalized for COVID-19 and (2) reporting data regarding HbA1c values before infection or at hospital admission in relation to COVID-19 mortality or worsening. Descriptive statistics, HbA1c values, odds ratios (ORs) and hazard ratios were extracted from seven observational studies and generic inverse variance (random effects) of OR was used to estimate the effect of HbA1c on COVID-19 outcome.

RESULTS

HbA1c was linearly associated with an increased COVID-19 mortality or worsening when considered as a continuous variable (OR 1.01 [1.01, 1.01]; p < 0.00001). Similarly, when analysing studies providing the number of events according to the degree of glycaemic control among various strata, a significantly increased risk was observed with poor glycaemic control (OR 1.15 [1.11, 1.19]; p < 0.00001), a result corroborated by sensitivity analysis.

CONCLUSIONS

Notwithstanding the large heterogeneity in study design and patients' characteristics in the few available studies, data suggest that patients with diabetes and poor glycaemic control before infection might have an increased risk of COVID-19 related mortality.

Primary Adipocytes as a Model for Insulin Sensitivity

Obesity and its comorbidity insulin resistance lead to the development of chronic metabolic diseases, such as impaired fasted blood glucose and type 2 diabetes. Adipose tissue plays an important role in whole-body glucose homeostasis, particularly in obese individuals; therefore, many in vivo models of type 2 diabetes are obese, such as Lep^ob/ob and Lepr^db/db mice or ZDF rats. Primary adipocytes therefore represent an attractive in vitro model to study insulin-mediated glucose uptake to investigate the mechanisms of insulin resistance and explore the potential insulin-sensitizing properties of new antidiabetic drugs.Primary adipocytes are isolated by collagenase digestion of adipose tissue, Glucose transport is evaluated by the measurement of intracellular uptake of a tracer (D-[U¹⁴C] glucose). The uptake of [U-¹⁴ C] glucose reflects directly glucose transport.In this chapter, we will describe the protocol for the isolation of primary rodent adipocytes and the measurement of basal and insulin-stimulated glucose uptake.

Primary Prevention of Atherosclerotic Cardiovascular Disease in Women

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of morbidity and mortality among women. Despite improvements in cardiovascular disease prevention efforts, there remain gaps in cardiovascular disease awareness among women, as well as age and racial disparities in ASCVD outcomes for women. Disparity also exists in the impact the traditional risk factors confer on ASCVD risk between women and men, with smoking and diabetes both resulting in stronger relative risks in women compared to men. Additionally there are risk factors that are unique to women (such as pregnancy-related factors) or that disproportionally affect women (such as auto-immune disease) where preventive efforts should be targeted. Risk assessment and management must also be sex-specific to effectively reduce cardiovascular disease and improve outcomes among women. Evidence supports the use of statin therapy for primary prevention in women at higher ASCVD risk. However, some pause should be given to prescribing aspirin therapy in women without known ASCVD, with most evidence supporting the use of aspirin for women≥65 years not at increased risk for bleeding. This review article will summarize (1) traditional and non-traditional assessments of ASCVD risk and (2) lifestyle and pharmacologic therapies for the primary prevention of ASCVD in women.

Prevalence of metabolic syndrome in type 2 diabetes mellitus patients

Background:

The diabetic condition is influenced by several factors, some of which can accelerate the disease's progression to various complications that aggravate the morbidity.

Aims:

This study aimed at determining the prevalence of metabolic syndrome (MetS) and its individual components and the most critical predictive risk factors of MetS in type 2 diabetic patients.

Materials and Methods:

This cross-sectional study involved 150 type 2 diabetes mellitus patients and was conducted at the Diabetes Centre of the Komfo Anokye Teaching Hospital in Kumasi, the Ashanti Region of Ghana, from February, 2013 to April, 2013. The study involved the use of a questionnaire to obtain some information on the diabetics, undertaking anthropometric measurements, as well as collecting blood samples for the measurement of some biochemical parameters; fasting blood glucose and lipid profile. MetS was defined according to the National Cholesterol Education Program/Adult Treatment Panel III criteria.

Results:

The prevalence of MetS was 58% in the studied Ghanaian population. Hypertension was the commonest risk factor (60%), followed by central obesity (48.67%) and dyslipidemia (37%). Female type 2 diabetics had a higher prevalence of MetS, and carried more components than their male counterparts. Regression analysis showed three factors; femininity, high body mass index and low educational status were the most critical predictive risk factors of MetS, according to this study.

Conclusion:

With hypertension being the commonest component, future cardiovascular disease prevention strategies should focus attention on its management and prevention, through education.

Body composition and Basal metabolic rate in women with type 2 diabetes mellitus

Objective. The aim of this study was to determine which of the seven selected equations used to predict basal metabolic rate most accurately estimated the measured basal metabolic rate. Methods. Twenty-eight adult women with type 2 diabetes mellitus participated in this cross-sectional study. Anthropometric and biochemical variables were measured as well as body composition (by absorptiometry dual X-ray emission) and basal metabolic rate (by indirect calorimetry); basal metabolic rate was also estimated by prediction equations. Results. There was a significant difference between the measured and the estimated basal metabolic rate determined by the FAO/WHO/UNU (P value < 0.021) and Huang et al. (P value ≤ 0.005) equations. Conclusion. The calculations using Owen et al's. equation were the closest to the measured basal metabolic rate.

Muscle inflammatory signaling in response to 9 days of physical inactivity in young men with low compared with normal birth weight

OBJECTIVE

The molecular mechanisms linking physical inactivity and muscle insulin resistance in humans have been suggested to include increased muscle inflammation, possibly associated with impaired oxidative metabolism. We employed a human bed rest study including 20 young males with normal birth weight (NBW) and 20 with low birth weight (LBW) and increased risk of diabetes.

METHODOLOGY

The subjects were studied before and after 9 days of bed rest using the euglycemic-hyperinsulinemic clamp and muscle biopsy excision. Muscle inflammatory status was assessed as nuclear factor-κB (NF-κB) activity and mRNA expression of the pro-inflammatory MCP1 (CCL2) and IL6 and the macrophage marker CD68. Furthermore, mRNA expression of genes central to oxidative phosphorylation (OXPHOS) was measured including ATP5O, COX7A1, NDUFB6, and UQCRB.

RESULTS

At baseline, muscle inflammatory status was similar in NBW and LBW individuals. After bed rest, CD68 expression was increased in LBW (P=0.03) but not in NBW individuals. Furthermore, expression levels of all OXPHOS genes were reduced after bed rest in LBW (P ≤ 0.05) but not in NBW subjects and were negatively correlated with CD68 expression in LBW subjects (P ≤ 0.03 for all correlations). MCP1 expression and NF-κB activity were unaffected by bed rest, and IL6 expression was too low for accurate measurements. None of the inflammatory markers correlated with insulin sensitivity.

CONCLUSIONS

Although LBW subjects exhibit disproportionately elevated CD68 mRNA expression suggesting macrophage infiltration and reduced OXPHOS gene expression when exposed to bed rest, our data altogether do not support the notion that bed rest-induced (9 days) insulin resistance is caused by increased muscle inflammation.

New concepts in dyslipidemia in the metabolic syndrome and diabetes

Trials have revealed that cardiovascular risk is not uniform in the population, but is distributed in a "risk pyramid." Diabetic patients with prior cardiovascular disease (CVD) are at greatest risk. Nondiabetic patients with CVD, diabetic patients without CVD, and subjects with the metabolic syndrome form the next three risk categories. The presence of insulin resistance-related metabolic abnormalities is a common denominator in this risk pyramid. Insulin resistance is a core defect in type 2 diabetes and the metabolic syndrome. Because insulin resistance may cause the atherogenic dyslipidemia that is commonly associated with these conditions, therapeutic strategies that combat insulin resistance could substantially reduce cardiovascular risk. Evidence suggests that defects in mitochondrial oxidative phosphorylation (which may be inherited, age related, or lifestyle acquired) may play a critical role in the pathogenesis of insulin resistance. Reduced mitochondrial oxidative phosphorylation can be partially reversed by improved diet, increased exercise, and administration of peroxisome proliferator-activated receptor-alpha agonists (omega-3 fatty acids and fibrates). Statin therapy has demonstrated clinical benefits in insulin-resistant patients but residual cardiovascular risk remains elevated. Fibrates also improve the lipid profile and reduce cardiovascular risk in a variety of insulin-resistant populations. Affected individuals should be targeted for therapeutic lifestyle intervention. Patients with atherogenic dyslipidemia who have developed insulin resistance, the metabolic syndrome, or type 2 diabetes should receive more intensive interventions including, where appropriate, statin-fibrate combination therapy, to comprehensively modify the lipid profile together with aggressive control of blood pressure and glucose to minimize risk in this very high-risk population.

Predicting and characterizing selective multiple drug treatments for metabolic diseases and cancer

BACKGROUND

In the field of drug discovery, assessing the potential of multidrug therapies is a difficult task because of the combinatorial complexity (both theoretical and experimental) and because of the requirements on the selectivity of the therapy. To cope with this problem, we have developed a novel method for the systematic in silico investigation of synergistic effects of currently available drugs on genome-scale metabolic networks.

RESULTS

The algorithm finds the optimal combination of drugs which guarantees the inhibition of an objective function, while minimizing the side effect on the other cellular processes. Two different applications are considered: finding drug synergisms for human metabolic diseases (like diabetes, obesity and hypertension) and finding antitumoral drug combinations with minimal side effect on the normal human cell. The results we obtain are consistent with some of the available therapeutic indications and predict new multiple drug treatments. A cluster analysis on all possible interactions among the currently available drugs indicates a limited variety on the metabolic targets for the approved drugs.

CONCLUSION

The in silico prediction of drug synergisms can represent an important tool for the repurposing of drugs in a realistic perspective which considers also the selectivity of the therapy. Moreover, for a more profitable exploitation of drug-drug interactions, we have shown that also experimental drugs which have a different mechanism of action can be reconsider as potential ingredients of new multicompound therapeutic indications. Needless to say the clues provided by a computational study like ours need in any case to be thoroughly evaluated experimentally.

Obesity is associated with impaired endothelial function in the postprandial state

Adequate microvascular perfusion is essential for the regulation of tissue metabolism. Therefore, defects in microvascular function may play a role in obesity-associated insulin resistance. Steady-state hyperinsulinemia during a euglycemic hyperinsulinemic clamp stimulates endothelium-dependent vasodilation and capillary recruitment, which contribute to increased glucose uptake. These phenomena have been shown to be blunted in obesity. If insulin's effects on microcirculatory function indeed play a physiological role in regulating insulin-mediated glucose uptake, such effects should be demonstrable not only during steady-state hyperinsulinemia, but also after meal ingestion. We investigated whether similar responses occur after ingestion of a glucose load or a mixed meal. We examined the effects of a glucose drink, a mixed meal drink, or a control drink (water) on skin capillary density (i.e. baseline capillary density, hyperemic capillary recruitment, and density during venous congestion, using capillaroscopy) and skin endothelium-(in)dependent vasodilation (using laser-Doppler flowmetry with iontophoresis of acetylcholine and sodium nitroprusside) in 20 lean and 19 obese individuals. In lean individuals, neither the glucose nor the mixed meal drink induced a significant effect on capillary density or endothelium-(in)dependent vasodilation. Possibly this is related to the modest plasma insulin levels as compared to the insulin clamp. In obese individuals, the mixed meal drink, compared to the control drink, decreased baseline skin perfusion (P<0.05) and acetylcholine-mediated vasodilation (P<0.05), while no effect of the drinks on capillary density was found. Compared to lean individuals, obese individuals had impaired acetylcholine-mediated vasodilation after meal ingestion (P=0.02). The latter findings are consistent with impaired postprandial microvascular function in obesity.

Early and longer term effects of gastric bypass surgery on tissue-specific insulin sensitivity and beta cell function in morbidly obese patients with and without type 2 diabetes

AIMS/HYPOTHESIS

Bariatric surgery consistently induces remission of type 2 diabetes. We tested whether there are diabetes-specific mechanisms in addition to weight loss.

METHODS

We studied 25 morbidly obese patients (BMI 51.7 ± 1.5 kg/m(2) [mean ± SEM]), 13 with non-insulin-treated type 2 diabetes (HbA(1c) 7.1 ± 0.5% [54 ± 5 mmol/mol]), before and at 2 weeks and 1 year after Roux-en-Y gastric bypass (RYGB). Lean (n = 8, BMI 23.0 ± 0.5 kg/m(2)) and obese (n = 14) volunteers who were BMI-matched (36.0 ± 1.2) to RYGB patients at 1 year after surgery served as controls. We measured insulin-stimulated glucose disposal (M) and substrate utilisation (euglycaemic clamp/indirect calorimetry), endogenous glucose production (EGP) by 6,6-[(2)H(2)]glucose, lipolysis (rate of appearance of [(2)H(5)]glycerol) and beta cell function (acute insulin response to i.v. glucose [AIR] as determined by C-peptide deconvolution).

RESULTS

At baseline, all obese groups showed typical metabolic abnormalities, with M, glucose oxidation and non-oxidative disposal impaired, and EGP, lipolysis, lipid oxidation and energy expenditure increased. Early after RYGB plasma glucose and insulin levels, and energy expenditure had decreased, while lipid oxidation increased, with M, EGP and AIR unchanged. At 1 year post-RYGB (BMI 34.4 ± 1.1 kg/m(2)), all diabetic patients were off glucose-lowering treatment and mean HbA(1c) was 5.4 ± 0.14% (36 ± 2 mmol/mol) (p = 0.03 vs baseline); AIR also improved significantly. In all RYGB patients, M, substrate oxidation, EGP, energy expenditure and lipolysis improved in proportion to weight loss, and were therefore similar to values in obese controls, but still different from those in lean controls.

CONCLUSIONS/INTERPRETATION

In morbidly obese patients, RYGB has metabolic effects on liver, adipose tissue, muscle insulin sensitivity and pattern of substrate utilisation; these effects can be explained by energy intake restriction and weight loss, the former prevailing early after surgery, the latter being dominant in the longer term.

Relationships of adrenoceptor polymorphisms with obesity

Obesity, hypertension, and type 2 diabetes are rapidly growing public health problems. Heightened sympathetic nerve activity is a well-established observation in obesity, hypertension, and type 2 diabetes. Human obesity, hypertension, and diabetes have strong genetic as well as environmental determinants. Reduced energy expenditure and resting metabolic rate are predictive of weight gain, and the sympathetic nervous system participates in regulating energy balance through thermogenesis. The thermogenic effects of catecholamines in obesity are mainly mediated via the β2, and β3-adrenergic receptors in humans. Further, β2-adrenoceptors importantly influence vascular reactivity and may regulate blood pressure. β-adrenoceptor polymorphisms have also been associated with adrenoceptor desensitization, increased adiposity, insulin resistance, and enhanced sympathetic nervous activity. Many epidemiological studies have shown strong relationships between adrenoceptor polymorphisms and obesity, but the observations have been discordant. This paper will discuss the current topics involving the influence of the sympathetic nervous system and β2- and β3-adrenoceptor polymorphisms in obesity.

Maternal zinc deficiency in rats affects growth and glucose metabolism in the offspring by inducing insulin resistance postnatally

Interactions among zinc (Zn), insulin, and glucose metabolism are complex. Maternal Zn deficiency affects maternal carbohydrate metabolism, but the mechanisms underlying changes in glucose homeostasis of offspring are not well understood. Rats consumed Zn-deficient (ZnD; 7 microg/g) or control (ZnC; 25 microg/g) diets ad libitum from 3 wk preconception to 21 d postparturition. Litters were culled to 7 pups/dam postnatally and pups were allowed to nurse their original mothers; after weaning, pups were fed nonpurified diet. Insulin and glucose tolerance tests were performed on the pups at wk 5 and 10. Although there was no difference in birth weight between groups, ZnD pups weighed significantly more than controls by d 10 (+5%) and 20 (+10%). Both blood glucose and serum insulin-like growth factor (IGF-1) concentrations at wk 3 were significantly higher in ZnD pups than in controls. Both male and female ZnD rats were less sensitive to insulin and glucose stimulation than controls at wk 5 and 10. At wk 15, serum leptin concentrations were higher in male ZnD rats than in controls. Phosphorylation of muscle Akt protein, an insulin receptor (IR) signaling intermediate, was lower in female ZnD rats than in controls at wk 15, but they did not differ in phosphorylation of IR. Maternal Zn deficiency resulted in greater serum IGF-1 concentrations and the excessive postnatal weight gain in their offspring as well as impaired subsequent glucose sensitivity. It was associated with gender-specific alterations in the serum leptin concentration and the insulin signaling pathway. These findings suggest that suboptimal maternal Zn status induces long-term changes in the offspring related to abnormal glucose tolerance.

Exposure of the pregnant rat to low protein diet causes impaired glucose homeostasis in the young adult offspring by different mechanisms in males and females

The understanding of the mechanisms by which gender dimorphisms are involved in the modulation of insulin sensitivity and glucose tolerance can be crucial to unravel the development of type 2 diabetes. Rats treated with a low protein diet (LP, 8% protein content) during pregnancy and lactation have a reduced beta-cell mass at birth and a reduced insulin secretion at weaning. In this study we examined the effect of LP diet on glucose homeostasis from birth to adulthood when offspring previously exposed to LP were subsequently switched to control diet (C, 20% protein content) at weaning. The LP group had a reduced body weight after weaning compared to the C-fed rats, although their food intake was not significantly different. Furthermore, LP males had a significant increase in visceral adiposity relative to their body weight (P < 0.05). Intraperitoneal glucose tolerance test (IGTT) showed that glucose clearance was unchanged until 130 days of age when LP-fed females showed elevated blood glucose compared to C, despite similar plasma insulin levels. Females also demonstrated a significant reduction in mean pancreatic islet number, individual islet size and beta cell mass. However, no differences in IGTT or islet morphometry were observed in LP males, although basal insulin levels were twofold higher. Akt phosphorylation in response to insulin was reduced in adipose and skeletal muscle of adult rats following exposure to LP diet in early life when compared to control-fed animals, but this was only apparent in males. Plasma testosterone levels were also reduced in males at 130 days age. These data suggest that the development of impaired glucose homeostasis in offspring of LP-fed rats is likely to occur by different mechanisms in males and females.

Menopause and cardiovascular disease: the evidence

Menopause is a risk factor for cardiovascular disease (CVD) because estrogen withdrawal has a detrimental effect on cardiovascular function and metabolism. The menopause compounds many traditional CVD risk factors, including changes in body fat distribution from a gynoid to an android pattern, reduced glucose tolerance, abnormal plasma lipids, increased blood pressure, increased sympathetic tone, endothelial dysfunction and vascular inflammation. Many CVD risk factors have different impacts in men and women. In postmenopausal women, treatment of arterial hypertension and glucose intolerance should be priorities. Observational studies and randomized clinical trials suggest that hormone replacement therapy (HRT) started soon after the menopause may confer cardiovascular benefit. In contrast to other synthetic progestogens used in continuous combined HRTs, the unique progestogen drospirenone has antialdosterone properties. Drospirenone can therefore counteract the water- and sodium-retaining effects of the estrogen component of HRT via the renin-angiotensin-aldosterone system, which may otherwise result in weight gain and raised blood pressure. As a continuous combined HRT with 17beta-estradiol, drospirenone has been shown to significantly reduce blood pressure in postmenopausal women with elevated blood pressure, but not in normotensive women. Therefore, in addition to relieving climacteric symptoms, drospirenone/17beta-estradiol may offer further benefits in postmenopausal women, such as improved CVD risk profile.

Loss of protein kinase Cbeta function protects mice against diet-induced obesity and development of hepatic steatosis and insulin resistance

Obesity is an energy balance disorder in which intake is greater than expenditure, with most excess calories stored as triglyceride (TG). We previously reported that mice lacking the beta-isoform of protein kinase C (PKCbeta), a diacylglycerol- and phospholipid-dependent kinase, exhibit marked reduction in the whole body TG content, including white adipose tissue (WAT) mass. To investigate the role of this signaling kinase in metabolic adaptations to severe dietary stress, we studied the impact of a high-fat diet (HFD) on PKCbeta expression and the effect of PKCbeta deficiency on profound weight gain. We report herein that HFD selectively increased PKCbeta expression in obesity-prone C57BL/6J mice, specifically in WAT; the expression levels were little or unchanged in the liver, muscle, kidney, and heart. Basal PKCbeta expression was also found to be elevated in WAT of obese ob/ob mice. Remarkably, mice lacking PKCbeta were resistant to HFD-induced obesity, showing significantly reduced WAT and slightly higher core body temperatures. Unlike lean lipodystrophic mouse models, these mice did not have fatty livers, nor did they exhibit insulin resistance. Moreover, PKCbeta(-/-) mice exhibited changes in lipid metabolism gene expression, and such alterations were accompanied by significant changes in serum adipokines. These observations suggest that PKCbeta deficiency induced a unique metabolic state congruous with obesity resistance, thus raising the possibility that dysregulation of PKCbeta expression could contribute to dietary fat-induced obesity and related disorders.

Comparison of rates and risk factors for developing chronic renal insufficiency, proteinuria and metabolic acidosis after radical or partial nephrectomy

OBJECTIVE

To investigate the incidence of and risk factors for developing chronic renal insufficiency (CRI), proteinuria and metabolic acidosis (MA) in patients treated with radical nephrectomy (RN) or nephron-sparing surgery (NSS).

PATIENTS AND METHODS

We retrospectively reviewed 749 patients (mean age 57.7 years; mean follow-up 6.4 years) who had RN or NSS for renal tumours between July 1987 and June 2006 at our institution. The demographics and outcomes were analysed and recorded. The primary outcome variable was the development of an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m(2), with secondary outcomes being the development of a serum creatinine level of > or =2.0 mg/dL, MA (serum bicarbonate <22 mmol/L), and proteinuria (> or =1+ on dipstick testing). Multivariate logistic regression (MV) was used to identify risk factors for developing an eGFR of <60 mL/min/1.73 m(2), a creatinine level of > or =2.0 mg/dL and MA.

RESULTS

Of the 749 patients, 499 had RN and 250 NSS; there were no significant demographic differences between the groups. After surgery a significantly greater proportion of the RN than the NSS group had a low eGFR (44.7% vs 16.0%, P < 0.001), MA (12.8% vs 7.2%, P = 0.02), proteinuria (22.2% vs 13.2%, P = 0.003) and elevated creatinine (14.2% vs 8.4%, P = 0.022). MV showed that diabetes mellitus (odds ratio 8.96, P = 0.002), RN (5.32, P < 0.001), hypertension (4.55, P = 0.003), a body mass index (BMI) of > or =30 kg/m(2) (3.51, P = 0.017), age > or =60 years (2.91, P = 0.015) and smoking (2.44, P = 0.014) were risk factors for developing a low eGFR; and that age > or =60 years (2.00, P = 0.019), diabetes mellitus (10, P < 0.001), hypertension (7.41, P = 0.002), smoking (5.29, P < 0.001) and RN (3.08, P < 0.001) were risk factors for developing an elevated creatinine level; and that being male (2.50, P = 0.019), age > or =60 years (3.13, P = 0.002), a BMI > or =30 (3.52, P < 0.001), RN (9.82, P < 0.001), preoperative eGFR <60 (9.71, P < 0.001) and elevated creatinine (5.9, P = 0.008) were risk factors for developing MA.

CONCLUSIONS

Patients undergoing RN had significantly greater CRI, MA and proteinuria rates than a well-matched group undergoing NSS. In addition to RN, age > or =60 years, diabetes mellitus, hypertension and smoking were associated with progression to CRI after surgery.

Overweight and obesity among Ghanaian residents in The Netherlands: how do they weigh against their urban and rural counterparts in Ghana?

OBJECTIVE

To investigate differences in overweight and obesity between first-generation Dutch-Ghanaian migrants in The Netherlands and their rural and urban counterparts in Ghana.

DESIGN

Cross-sectional study.

SUBJECTS

A total of 1471 Ghanaians (rural Ghanaians, n 532; urban Ghanaians, n 787; Dutch-Ghanaians, n 152) aged > or = 17 years.

MAIN OUTCOME MEASURES

Overweight (BMI > or = 25 kg/m2) and obesity (BMI > or = 30 kg/m2).

RESULTS

Dutch-Ghanaians had a significantly higher prevalence of overweight and obesity (men 69.1%, women 79.5%) than urban Ghanaians (men 22.0%, women 50.0%) and rural Ghanaians (men 10.3%, women 19.0%). Urban Ghanaian men and women also had a significantly higher prevalence of overweight and obesity than their rural Ghanaian counterparts. In a logistic regression analysis adjusting for age and education, the odds ratios for being overweight or obese were 3.10 (95% CI 1.75, 5.48) for urban Ghanaian men and 19.06 (95% CI 8.98, 40.43) for Dutch-Ghanaian men compared with rural Ghanaian men. Among women, the odds ratios for being overweight and obese were 3.84 (95% CI 2.66, 5.53) for urban Ghanaians and 11.4 (95% CI 5.97, 22.07) for Dutch-Ghanaians compared with their rural Ghanaian counterparts.

CONCLUSION

Our current findings give credence to earlier reports of an increase in the prevalence of overweight/obesity with urbanization within Africa and migration to industrialized countries. These findings indicate an urgent need to further assess migration-related factors that lead to these increases in overweight and obesity among migrants with non-Western background, and their impact on overweight- and obesity-related illnesses such as diabetes among these populations.

Cardiovascular risks and their long-term clinical outcome in patients with subclinical Cushing's syndrome

Although subclinical Cushing's syndrome has been commonly experienced, details of the clinical outcome and its indication for adrenalectomy have yet to be established. In the present study, we investigated the prevalence of cardiovascular risks, their clinical outcome during long-term follow up before and after adrenalectomy in 20 patients with subclinical Cushing's syndrome. We also correlated the hypercortisolism and age with the cardiovascular risks and the clinical outcome. The prevalence of hypertension, impaired glucose metabolism, dyslipidemia, and obesity was 45%, 65%, 65%, and 25%, respectively. In the non-operated group (n = 12), six patients (50%) showed deterioration of at least one of the cardiovascular risks. Four patients showed an increase of at least one risk, while none of the patients showed a decrease in the number of risks. One patient developed overt Cushing's syndrome. In the operated group (n = 10) including two operated patients of the non-operated group, eight patients (80%) showed an improvement of at least one of the cardiovascular risks after surgery and five patients (50%) showed a decrease of at least one risk. The prognosis in terms of the changes of the cardiovascular risks was significantly better in the operated group than in the non-operated group (p<0.001). Neither the hypercortisolism nor age correlated to the presence and the clinical outcome of the cardiovascular risks. The present study clearly demonstrated probability of deterioration during the clinical course and improvement after adrenal surgery in patients with subclinical Cushing's syndrome. Careful follow-up of the cardiovascular risks is therefore warranted. Adrenalectomy could be a treatment of choice despite the hypercortisolism and age of the patients, especially when the cardiovascular risks show signs of deterioration.

The association of intensity and overall level of physical activity energy expenditure with a marker of insulin resistance

AIMS/HYPOTHESIS

Physical activity is important in preventing insulin resistance, but it is unclear which dimension of activity confers this benefit. We examined the association of overall level and intensity of physical activity with fasting insulin level, a marker of insulin resistance.

METHODS

This was a cross-sectional analysis of the Medical Research Council Ely population-based cohort study (2000--2002). Physical activity energy expenditure (PAEE) in kJ kg(-1) min(-1) was measured by heart rate monitoring with individual calibration over a period of 4 days. The percentage of time spent above 1.5, 1.75 and 2 times resting heart rate (RHR) represented all light-to-vigorous, moderate-to-vigorous and vigorous activity, respectively.

RESULTS

Data from a total of 643 non-diabetic individuals (319 men, 324 women) aged 50 to 75 years were analysed. In multivariate linear regression analyses, adjusting for age, sex and body fat percentage, PAEE was significantly associated with fasting insulin (pmol/l) (beta = -0.875, p = 0.006). Time (% of total) spent above 1.75 x RHR and also time spent above 2 x RHR were both significantly associated with fasting insulin (beta = -0.0109, p = 0.007 and beta = -0.0365, p = 0.001 respectively), after adjusting for PAEE, age, sex and body fat percentage. Time spent above 1.5 x RHR was not significantly associated with fasting insulin in a similar model (beta = -0.0026, p = 0.137).

CONCLUSIONS/INTERPRETATION

The association between PAEE and fasting insulin level, a marker of insulin resistance, may be attributable to the time spent in moderate-to-vigorous and vigorous activity, but not to time spent in light-intensity physical activity.

[Analysis of resting metabolic rate evaluated by indirect calorimetry in obese women with low and high caloric intake]

The aim of this study was to evaluate if obese women with the lowest values of caloric intake (CI) determined by food questionnaire also present the lowest values of resting metabolic rate (RMR), which could lead to excessive weight gain, caused by changes in energy balance. With this purpose, 77 obese women, with IMC>30 kg/m2, aged 20 to 45 years, had their physical activity level and CI evaluated. According to the values of CI obtained from food intake reports, the participants were divided in 3 groups: low (G1), medium (G2), high (G3) CI and were submitted to indirect calorimetry. Height, weight, body surface area (BSA), fat free mass and fat mass measured by bioimpedance were evaluated. The highest values of weight, BSA an fat mass were obtained in G1, as well as values above 1.2 for the CI:RMR ratio, which indicates a probable underestimation of CI. The highest values of physical activity and RMR were observed in the G3 (with high caloric intake). In conclusion, this paper shows that a tendency towards underestimation of self-reported caloric intake exists among obese women and that the maintenance of weight in some patients can be due to their low level of physical activity.

Managing cardiovascular risk in menopausal women

Blood pressure control and prevention of glucose intolerance are primary factors in overcoming the increased cardiovascular risks in menopausal women. This heightened risk may partially be explained by the metabolic syndrome - a precursor of type 2 diabetes - in which the renin-angiotensin-aldosterone system may play a pivotal role. Once diabetes occurs, the cardiovascular risk is considerably greater in postmenopausal women than in men - especially if hypertension is also present. An additional risk factor, weight gain, is common in postmenopausal women not treated with hormone replacement therapy. Rigorous control of blood pressure has been shown to be particularly beneficial in women with metabolic syndrome; a reduction in blood pressure can reduce the mortality rate of ischemic stroke. The administration of hormone replacement therapy can also reduce the likelihood of coronary heart disease in postmenopausal women; therefore therapy should be started early in the menopausal transition to maximize cardiovascular protection. As such, an ideal hormone replacement therapy that can overcome hypertension, prevent body weight gain and control serum triglycerides offers an important advance in cardiovascular risk management during the menopause.

Sociodemographic variations in obesity among Ghanaian adults

Objectives:

To determine the sociodemographic associations of obesity in Ghana.

Design:

A cross-sectional descriptive study was conducted on a sample of 6300 adults aged 25 years and over who were selected by random cluster sampling.

Setting:

Two urban (high-class and low-class suburbs) and a rural community in Accra, Ghana.

Subjects and methods:

In total, 4731 (1857 males, 2874 females) subjects participated. Demographic data were obtained by a questionnaire and height and weight were determined with subjects in light clothing and without shoes.

Results:

The overall crude prevalence of overweight and obesity was 23.4 and 14.1%, respectively. The rates of overweight (27.1 vs. 17.5%) and obesity (20.2 vs. 4.6%) were higher in females than males. Obesity increased with age up to 64 years. There were more overweight and obesity in the urban high-class residents compared with the low-class residents and in urban than rural subjects. Overweight and obesity were highest among the Akan and Ga tribes and relatively low among Ewes. Subjects with tertiary education had the highest prevalence of obesity (18.8%) compared with less literate and illiterate subjects (12.5–13.8%). Subjects whose jobs were of a sedentary nature had higher levels of obesity (15%) than subjects whose jobs involved heavy physical activity (10%). Subjects who did not engage in leisure-time physical activity were more obese than those who had three or more sessions of leisure-time physical activity per week (15.3 vs. 13.5%).

Conclusions:

Overweight and obesity are common among residents in the Accra area. Older age, female gender, urban, high-class residence, sedentary occupation and tertiary education were associated with higher levels of obesity. Policies and programmes that promote healthy lifestyles may prove beneficial.

Long-term effects of tumor necrosis factor-α treatment on insulin signaling pathway in HepG2 cells and HepG2 cells overexpressing constitutively active Akt/PKB

Tumor necrosis factor-alpha (TNF-alpha) mediated attenuation of insulin signaling pathway is an important cause in several disorders like obesity, obesity linked diabetes mellitus. TNF-alpha actions vary depending upon concentration and time of exposure in various cells. In the present study, the effects of long-term TNF-alpha (1 ng/ml) exposure on the components of insulin signaling pathway in HepG2 and HepG2 cells overexpressing constitutively active Akt1/PKB-alpha (HepG2-CA-Akt/PKB) have been investigated. In parental HepG2 cells, TNF-alpha treatment for 24 h reduced the phosphorylation of Akt1/PKB-alpha and GSK-3beta and under these conditions cells also showed reduced insulin responsiveness in terms of Akt1/PKB-alpha and GSK-3beta phosphorylation. TNF-alpha pre-incubated HepG2-CA-Akt/PKB cells showed lower reduction in Akt1/PKB-alpha and GSK-3beta phosphorylation and insulin responsiveness after 24 h as compared to parental HepG2 cells. We report that the long-term TNF-alpha pre-incubation in both parental HepG2 and HepG2-CA-Akt/PKB-alpha cells leads to the reduction in the levels of IRS-1 without altering the levels of IRS-2. In order to understand the reason for the differential insulin resistance in both the cell types, the effect of long-term TNF-alpha treatment on the proteins upstream to Akt/PKB was investigated. TNF-alpha pre-incubation also showed reduced insulin-stimulated Tyr phosphorylation of insulin receptor (IR-beta) in both the cell types, moreover hyperphosphorylation of IRS-1 at Ser 312 residue was observed in TNF-alpha pre-incubated cells. As hyperphosphorylation of IRS-1 at Ser 312 can induce its degradation, it is possible that reduced insulin responsiveness after long-term TNF-alpha pre-incubation observed in this study is due to the decrease in IRS-1 levels.

Determinants of Insulin Resistance in Renal Transplant Recipients

BACKGROUND

Insulin resistance is considered to play an important role in the development of cardiovascular disease, which limits long-term renal transplant survival. Renal transplant recipients are more insulin-resistant compared with healthy controls. It is not known to date which factors relate to this excess insulin resistance. Therefore, we investigated which factors are related to insulin resistance long-term after renal transplantation.

METHODS

All renal transplant recipients at our outpatient clinic with a functioning graft for more than one year were invited to participate. We excluded diabetic recipients. Recipient, donor, and transplant characteristics were collected as putative determinants. We used fasting insulin, homeostasis model assessment index, and McAuley's index as valid estimates of insulin resistance. Linear regression models were created to investigate independent determinants of all indexes.

RESULTS

A total of 483 recipients (57% male, 50+/-12 years) were analyzed at a median (interquartile range) time of 6.0 (2.6-11.6) years posttransplant. The most consistent determinants across all three indices were body mass index (P<0.001), waist-to-hip ratio (P<0.001), and prednisolone dose (P<0.05). Independent associations were present for total cholesterol (P<0.001), high-density lipoprotein cholesterol (P<0.001), creatinine clearance (P<0.05), recipient age (P<0.001), and gender (P< or =0.002). No independent associations were present for transplant-related factors such as acute rejection treatment or cytomegalovirus seropositivity.

CONCLUSIONS

Our results indicate that obesity, distribution of obesity, and prednisolone treatment are the predominant determinants of insulin resistance long term after transplantation. Insulin resistance after renal transplantation could be managed favorably by weight and prednisolone dose reduction, which may reduce cardiovascular disease.

Arterial Stiffness in HIV-Infected Patients Receiving Highly Active Antiretroviral Therapy

HIV-infected patients receiving highly active antiretroviral therapy (HAART) are at increased risk of cardiovascular events. Reported non-invasive techniques for assessment of blood pressure in this population have been limited to sphygmomanometry. The present cross-sectional study investigated the impact of antiretroviral therapy and the HAART-associated lipodystrophy on aortic blood pressure conditions and arterial stiffness in HAART-treated lipodystrophic ( n=42) and non-lipodys-trophic ( n=17) patients. Pulse wave analysis, novel to this population, was used to evaluate measures of arterial stiffness, including the heart rate corrected augmentation index, AgIHR. Results indicated no significant difference between the study groups in peripheral or aortic blood pressure and AgIHR. Significant correlates of AgIHR included age ( P=0.003), duration of antiretroviral therapy ( P=0.020), lamivudine therapy ( P=0.015) and ritonavir therapy ( P=0.016) as well as cumulative exposure to protease inhibitors ( P=0.030). Time since HIV diagnosis, severity of immunodeficiency or presence of HAART-associated lipodystrophy bore no relationship to AgIHR. In multivariate analysis, duration of antiretroviral therapy ( P=0.046), cumulative exposure to nucleoside reverse transcriptase inhibitors ( P=0.032) and to protease inhibitors ( P=0.011) were identified as independent factors predicting AgIHR. Prolonged antiretroviral treatment, thus, delineates as a risk factor for systemic arterial stiffness and the associated cardiovascular mortality.

Do centrally obese Chinese with normal BMI have increased risk of metabolic disorders?

BACKGROUND

Body mass index (BMI) and waist circumference are highly correlated. One or the other predicts the metabolic syndromes better, depending on characteristic of the population studied, such as age, gender, and ethnicity. We examined the impact of isolated central obesity, isolated BMI elevation, and the combined type of obesity on metabolic disorders, in order to shed lights on the strategy of obesity screening.

METHODS

The study subjects were Chinese aged 20 or above residing in Taiwan. Their data were derived from two large-scale studies: the Nutrition and Health Survey in Taiwan (NAHSIT 1993-1996) and the Cardiovascular Disease Risk Factor Two-township Study (CVDFACTS, 1994-1997). In evaluating the relations between obesity and health risks, the cut-points of BMI (> or =24 kg/m(2) for overweight) and waist circumference (> or =80 cm for women and > or =90 cm for men) recommended by Department of Health in Taiwan for Taiwanese people were used to define various types of obesity.

RESULTS

We found that there was a small but nontrivial proportion (1.7% for men and 4.0% for women) of Taiwanese people for whom BMI was in the normal range but their waist circumferences were above normal. These people were at a higher risk of developing metabolic syndromes than those with isolated BMI elevation. Their risks were close to that of the combined type.

CONCLUSIONS

In order to screen out high-risk obese individuals, isolated centrally obese subjects should not be overlooked. Therefore, we recommend to assess waist circumference in parallel to, not just sequential to the measurement of BMI in Chinese.

Sexual dimorphism in human lipid metabolism

The existing work demonstrates that striking differences exist between men and women in lipid kinetics. These differences cannot be explained simply by the presence and action of sex hormones and are not always due to secondary, phenotypic traits that characterize men and women (e.g., body-composition, regional fat distribution). In fact, some of these secondary traits may even be the result of sexual dimorphism in metabolism, and being of female or male genotype also determines intermediary metabolism. This review provides an overview of the currently available information regarding sexual dimorphism in human lipid metabolism but does not provide an in-depth account of current knowledge (due to limited space); it will be a broad introduction to those interested in the field and will, hopefully, stimulate further efforts to unravel the secrets of male and female metabolism. What has been discovered so far regarding differences in lipid metabolism between men and women is likely only the tip of the iceberg; clearly, more work is necessary to fully understand human substrate metabolism and the implications the presence of sexual dimorphism in the control of substrate kinetics has on the prevention and treatment of disease.

Postexercise insulin sensitivity is not impaired after an overnight lipid infusion

High plasma fatty acid availability and a positive energy balance in sedentary individuals reduce insulin sensitivity. This study's purpose was to determine whether high plasma fatty acid availability and systemic caloric excess after exercise also impair insulin sensitivity. On two separate occasions, seven nonobese women performed 90 min of exercise at approximately 65% peak oxygen uptake. In one trial, a lipid + heparin emulsion (Lipid) was infused overnight to increase plasma fatty acid availability. In the other trial, saline was infused as control. The next morning, a muscle biopsy was taken to measure muscle glycogen and intramuscular triglyceride (IMTG) concentrations. Three hours after the overnight infusion was stopped, insulin sensitivity was assessed with an intravenous glucose tolerance test, using minimal model analysis (Si). During the overnight infusions, plasma fatty acid concentration was approximately fourfold higher [means (SD): 0.84 (0.36) vs. 0.22 (0.09) mmol/l; P = 0.003], and the next morning IMTG concentration was approximately 30% greater [49.2 (6.6) vs. 38.3 (7.7) mmol/kg dry wt; P = 0.036] in Lipid compared with saline. However, muscle glycogen concentration was not different between trials (P = 0.82). Lipid caused a 24-h surplus of approximately 1100 kcal above energy balance (P = 0.00001), whereas energy balance was maintained in saline. Despite these differences in fatty acid and energy availability, Si the morning after exercise was not different between trials (P = 0.72). Thus insulin sensitivity the morning after a single exercise session was not reduced despite overnight exposure to a fourfold increase in plasma fatty acid concentration, elevated IMTG concentration, and systemic delivery of approximately 1,100-kcal excess.

Genetic determinants of energy expenditure and insulin resistance in diet-induced obesity in mice

Diet-induced obesity is the primary determinant of the current epidemic of diabetes. We have explored the role of genetics in this phenomenon, using C57Bl/6 (B6), 129S6/SvEvTac (129), and intercross (B6 x 129)F2 mice on a low- or high-fat diet. Over an 18-week period, B6 and F2 mice gained more weight, had higher levels of insulin and leptin, and showed greater glucose intolerance than 129 mice, despite lower food intake. By contrast, metabolic rate and diet-induced thermogenesis were significantly higher in the 129 mice. Genome-wide scans identified several quantitative trait loci, including a quantitative trait locus that was linked with hyperinsulinemia/insulin resistance on chromosome 14 in a region similar to that seen in mice with genetically induced insulin resistance. Microarray analysis indicated significant changes in expression levels between B6 and 129 mice in the identified chromosomal area of Wnt5a and protein kinase Cdelta (PKCdelta). Thus, caloric efficiency, i.e., the "thrifty gene," is a dominant-acting genetic determinant of diet-induced obesity in mice and can be linked to a locus on chromosome 14, including genes linked to adipose development and insulin sensitivity.

Influence of adiposity on tonic sympathetic support of resting metabolism in healthy adults

BACKGROUND

beta-Adrenergic receptor sympathetic nervous system (beta-AR SNS) support of resting metabolic rate (RMR) is attenuated with older age, female sex, and a sedentary lifestyle. Total and abdominal adiposity and/or body fat pattern modulate some SNS-mediated physiological functions.

OBJECTIVE

To determine if total and abdominal adiposity and/or body fat distribution are independently related to SNS support of RMR.

DESIGN

Cross-sectional comparison of beta-AR SNS support of RMR.

SUBJECTS

A total of 54 healthy male and female subjects aged 18-75 y.

MEASUREMENTS

RMR (ventilated hood, indirect calorimetry) before (baseline) and during complete beta-AR blockade; body composition by dual energy X-ray absorptiometry.

RESULTS

Forward stepwise multiple regression analysis using sex, exercise status, age group, %body fat, total adiposity, abdominal adiposity, and the ratio of abdominal adiposity to hip adiposity as variables revealed sex to be the strongest predictor, explaining 21% of the variability in beta-AR SNS support of RMR (P=0.0006). Age group explained an additional 4% and exercise status a further 4% (both P=0.10). %Body fat, total adiposity, abdominal adiposity, and the ratio of abdominal adiposity to hip adiposity did not enter the equation.

CONCLUSION

Total and abdominal adiposity and body fat pattern are not independent physiological determinants of beta-AR SNS support of RMR among healthy men and women. Moreover, further support is provided for our previous finding of attenuated beta-AR SNS support of RMR with age, female sex, and sedentary lifestyle.

Standard isolation of primary adipose cells from mouse epididymal fat pads induces inflammatory mediators and down-regulates adipocyte genes

Isolation and subsequent in vitro culture of primary adipose cells are associated with down-regulation of GLUT4 mRNA and simultaneous induction of GLUT1 gene expression. Progressive loss of insulin-responsive GLUT4 contributes to the decrease in insulin-mediated glucose uptake in these cells when cultured in vitro. The mechanisms underlying these alterations are unknown. Here, we report that the standard procedure for isolating primary adipose cells from mouse adipose tissue triggers induction of many genes encoding inflammatory mediators including TNF-alpha, interleukin (IL)-1 alpha, IL-6, multiple chemokines, cell adhesion molecules, acute-phase proteins, type I IL-1 receptor, and multiple transcription factors implicated in the cellular inflammatory response. Secretion of TNF-alpha protein was also significantly induced during the 2-h collagenase digestion of adipose tissue. Isolated primary adipose cells exhibit dramatic changes in expression of multiple mRNAs that are characteristic of TNF-alpha-treated 3T3-L1 adipocytes including down-regulation of many genes important for insulin action and triglyceride synthesis. Addition of TNF-alpha to primary adipose cells in culture did not change the kinetics or the extent of the repression of adipose cell-abundant genes. Moreover, TNF-alpha-neutralizing antibody failed to block the changes in gene transcription in isolated primary adipose cells. Also, the standard isolation procedure induced the expression of NF-kappa B family members and their target genes in primary adipose cells prepared from TNF-alpha-/- mice to the same extent as in cells isolated from wild-type mice and resulted in almost identical changes in global gene expression when these cells were cultured in vitro. Thus, these data suggest that the standard isolation procedure-triggered reprogramming of gene expression in primary adipose cells that results in decreased insulin sensitivity does not require TNF-alpha, at least in this in vitro model system, but may be dependent on other inflammatory cytokines produced by these cells.

Relationship between body mass index, serum cholesterol, leisure-time physical activity, and diet in a Mediterranean Southern-Europe population

The aim of the present study was to determine the relationship of BMI with other cardiovascular risk factors, leisure-time physical activity and diet. Participants were recruited in a cross-sectional population-based survey in a southern-Europe Mediterranean population (Spain); cardiovascular risk factors were measured, and leisure-time physical activity and diet intake were evaluated. Linear regression analysis adjusted for several confounders showed a significant, direct association of BMI and total cholesterol (P<0.005) and LDL-cholesterol (P<0.006), in men. HDL-cholesterol was inversely related to BMI in both sexes (P<0.0001). Higher BMI was more frequent in less-active men (P<0.04) but not in women. BMI increased significantly (P<0.0001) by 1.92 kg/m(2) with each 4.18 MJ consumed in men but not in women. Dietary intakes of carbohydrate (P<0.03), total fat (P<0.03) and saturated fatty acids (P<0.02) were directly associated with BMI in men but not in women, in whom protein intake was correlated (P<0.001) with BMI. Linear regression models including dietary components explained up to 10.6 and 21.1 % of BMI variability in men and women, respectively. Sex differences in the association of BMI with total cholesterol, and LDL-cholesterol, may account for the lower risk for CHD in women compared with men of similar BMI reported in the literature for the southern-Europe Mediterranean region. An increases of BMI may be more deleterious in populations in which it is accompanied by other risk factors such as a higher intake of total fat and, particularly, of saturated fatty acids, or lower leisure-time physical activity.

Insulin resistance as putative cause of chronic renal transplant dysfunction

Transplantation is the preferred organ replacement therapy for most patients with end-stage renal disease. Despite impressive improvements over recent years in the treatment of acute rejection, approximately half of all grafts will loose function within 10 years after transplantation. Chronic renal transplant dysfunction, also known as transplant atherosclerosis, is a leading cause of late allograft loss. To date, no specific treatment for chronic renal transplant dysfunction is available. Although its precise pathophysiology remains unknown, it is believed that it involves a multifactorial process of alloantigen-dependent and alloantigen-independent risk factors. Obesity, posttransplant diabetes mellitus, dyslipidemia, hypertension, and proteinuria have all been identified as alloantigen-independent risk factors. Notably, these recipient-related risk factors are well-known risk factors for cardiovascular disease, which cluster within the insulin resistance syndrome in the general population. Insulin resistance is considered the central pathophysiologic feature of this syndrome. It is therefore tempting to speculate that it is insulin resistance that underlies the recipient-related risk factors for chronic renal transplant dysfunction. Recognition of insulin resistance as a central feature underlying many, if not all, recipient-related risk factors would not only improve our understanding of the pathophysiology of chronic renal transplant dysfunction, but also stimulate development of new treatment and prevention strategies.

Relation of C-reactive protein to features of the metabolic syndrome in normal glucose tolerant, impaired glucose tolerant, and newly diagnosed type 2 diabetic subjects

OBJECTIVE

To determine the relationship between CRP levels and the components of MS in normal glucose tolerant (NGT), impaired glucose tolerant (IGT), and Type 2 diabetic subjects.

MATERIAL AND METHODS

A based cross-sectional population study was performed. Eligible subjects, men and non-pregnant women, 30 to 64 year of age, were randomly recruited. Subjects with acute or chronic diseases were excluded. Only newly diagnosed type 2 diabetic or hypertensive subjects were included. Disorders related to CRP increase, also were exclusion criteria. In accordance to WHO proposal, components of MS were: High Blood Pressure, Dyslipidemia, Obesity, and Microalbuminuria, and MS was defined, for the NGT, if at least two of the criteria were fulfilled and in addition the subject had insulin resistance. The MS in IGT and DM subjects was defined if at least two of the criteria were fulfilled.

RESULTS

CRP was significantly associated with MS for the NGT (Odds ratio -OR- 3.8, CI(95%) 1.6-14.8), IGT (OR 4.9, CI(95%) 1.2-15.5), and diabetes (OR 5.6, CI(95%) 1.9-10.2). For NGT, after adjustment for obesity, CRP was not longer associated with MS. After adjust for obesity and fasting glucose (FG), the relationship between CRP and MS for IGT was lost. Finally, after adjustment for obesity, FG, and microalbuminuria, CRP was not longer associated with MS for diabetic subjects.

CONCLUSIONS

This study show a significant relationship between CRP and MS which is maintained only by obesity in the NGT, by obesity and FG in the IGT, and by obesity, FG, and microalbuminuria in the newly diagnosed diabetic subjects.

Tumor necrosis factor-alpha suppresses adipocyte-specific genes and activates expression of preadipocyte genes in 3T3-L1 adipocytes: nuclear factor-kappaB activation by TNF-alpha is obligatory

Tumor necrosis factor-alpha (TNF-alpha) is a contributing cause of the insulin resistance seen in obesity and obesity-linked type 2 diabetes, but the mechanism(s) by which TNF-alpha induces insulin resistance is not understood. By using 3T3-L1 adipocytes and oligonucleotide microarrays, we identified 142 known genes reproducibly upregulated by at least threefold after 4 h and/or 24 h of TNF-alpha treatment, and 78 known genes downregulated by at least twofold after 24 h of TNF-alpha incubation. TNF-alpha-induced genes include transcription factors implicated in preadipocyte gene expression or NF-kappaB activation, cytokines and cytokine-induced proteins, growth factors, enzymes, and signaling molecules. Importantly, a number of adipocyte-abundant genes, including GLUT4, hormone sensitive lipase, long-chain fatty acyl-CoA synthase, adipocyte complement-related protein of 30 kDa, and transcription factors CCAAT/enhancer binding protein-alpha, receptor retinoid X receptor-alpha, and peroxisome profilerator-activated receptor gamma were significantly downregulated by TNF-alpha treatment. Correspondingly, 24-h exposure of 3T3-L1 adipocytes to TNF-alpha resulted in reduced protein levels of GLUT4 and several insulin signaling proteins, including the insulin receptor, insulin receptor substrate 1 (IRS-1), and protein kinase B (AKT). Nuclear factor-kappaB (NF-kappaB) was activated within 15 min of TNF-alpha addition. 3T3-L1 adipocytes expressing IkappaBalpha-DN, a nondegradable NF-kappaB inhibitor, exhibited normal morphology, global gene expression, and insulin responses. However, absence of NF-kappaB activation abolished suppression of >98% of the genes normally suppressed by TNF-alpha and induction of 60-70% of the genes normally induced by TNF-alpha. Moreover, extensive cell death occurred in IkappaBalpha-DN-expressing adipocytes after 2 h of TNF-alpha treatment. Thus the changes in adipocyte gene expression induced by TNF-alpha could lead to insulin resistance. Further, NF-kappaB is an obligatory mediator of most of these TNF-alpha responses.

What are obstructive sleep apnea patients being treated for prior to this diagnosis?

BACKGROUND

Patients with obstructive sleep apnea syndrome (OSAS) use health-care resources at higher rates than control subjects for years prior to diagnosis. Although obesity and certain cardiovascular disorders are more common in OSAS patients, the precise cause of increased health-care utilization is unclear.

OBJECTIVES

To examine the causes of increased utilization, and what patients with OSAS were being treated for prior to this diagnosis.

METHODS

We compared the records of 773 patients with OSAS to those of age-, gender-, geographic-, and physician-matched control subjects from the general population.

RESULTS

We found that sleep apnea patients used 23 to 50% more resources (defined by physician fees, physician visits, and hospital nights) in the 5 years prior to diagnosis than did control subjects. We examined the diagnoses made and found that apnea patients are at higher risk for hypertension (odds ratio [OR], 2.5; 95% confidence interval [CI], 2.0 to 3.3), congestive heart failure (OR, 3.9; 95% CI, 1.7 to 8.9), cardiac arrhythmias (OR, 2.2; 95% CI, 1.2 to 4.0), cardiovascular disease (OR, 2.6; 95% CI, 2.0 to 3.3), chronic obstructive airways disease (OR, 1.6; 95% CI, 1.2 to 2.0), and depression (OR, 1.4; 95% CI, 1.0 to 1.9). To control for the confounding effects of obesity and to determine the independent effects of body mass index (BMI), gender, age, degree of hypoxemia, apnea-hypopnea index, and sleepiness in the 773 patients, we performed a logistic regression analysis with the dependent variable being diagnosis, and a linear regression analysis with the dependent variable being measures of health-care utilization. Age and BMI were significant independent predictors of most cardiovascular diagnoses and arthropathy. Male gender predicted ischemic heart disease (OR, 2.98; 95% CI, 1.36 to 6.54), and female gender was predictive of chronic obstructive airways disease (OR, 2.63; 95% CI, 1.85 to 3.72) and depression (OR, 2.24; 95% CI, 1.45 to 3.44). The best model predicting health-care utilization measures was comprised of age, gender, and BMI, and explained 9%, 14%, and 8% of the variability in physician fees, number of physician claims, and number of physician visits, respectively.

CONCLUSION

Of all comorbid diagnoses, significantly increased utilization was found for cardiovascular disease and especially hypertension in the OSAS patients.

Insulin resistance after renal transplantation: impact of immunosuppressive and antihypertensive therapy

OBJECTIVE

The purpose of the present study was to validate various surrogate estimates of insulin sensitivity (IS) in a renal transplant population and to assess the influence of immunosuppressive and antihypertensive therapy on insulin resistance (IR) after renal transplantation.

RESEARCH DESIGN AND METHODS

A total of 167 consecutive renal transplant recipients without previously known diabetes underwent a 75-g oral glucose tolerance test (OGTT) 3 months after renal transplantation. A total of 43 patients also underwent a euglycemic-hyperinsulinemic glucose clamp study. Six OGTT-derived IS indexes were validated against the euglycemic-hyperinsulinemic glucose clamp-derived IS index (ISI(CLAMP)).

RESULTS

The OGTT-derived ISI(TX) correlated closely with the ISI(CLAMP) (r = 0.58, P < 0.001). The other surrogate estimates of IS were also significantly but less well correlated with the ISI(CLAMP) (Spearman's correlation; r = -0.45 to 0.41, P = 0.003-0.050). In the univariate model, BMI, daily prednisolone dose, creatinine clearance, hypertension, number of antihypertensive agents, and use of diuretics or beta-blockers were negatively associated with ISI(TX) (P < 0.05). After multiple regression analysis, BMI (P < 0.001), daily prednisolone dose (P < 0.001), cytomegalovirus infection (P = 0.030), and triglycerides (P = 0.034) were shown to be independent predictors of posttransplant IR.

CONCLUSIONS

The OGTT-derived ISI(TX) may be a useful estimate of IS in Caucasian renal transplant recipients. Increasing daily prednisolone dose is an independent predictor of IR after renal transplantation. Hypertension and the use of beta-blockers and diuretics may also deteriorate IR in this group of patients.

Circulating amylin in human essential hypertension: heritability and early increase in individuals at genetic risk

BACKGROUND

Human essential hypertension is a complex trait with poorly understood genetic determination. Insulin resistance is frequently associated with this trait.

OBJECTIVE

To determine whether a potentially pathogenic feature of the insulin-resistant state, circulating amylin (islet amyloid polypeptide, co-released with insulin from pancreatic islet beta-cells), is already increased in prehypertensive individuals (normotensive persons at genetic risk of hypertension because of family history), whether such individuals already differ in their amylin response to beta-cell stimulation, and whether plasma amylin concentration is heritable. Such features could establish increased circulating amylin as a hereditary 'intermediate phenotype' useful in genetic analyses of hypertension.

METHODS

Plasma amylin and insulin were measured in 283 medication-free individuals stratified by blood pressure status (82 hypertensive and 201 normotensive), and genetic risk (family history) of hypertension. Differences in means were tested by ANOVA, variances by F test, and frequency distributions by maximum likelihood analysis. Co-release of amylin and insulin was provoked by intravenous infusion of mixed amino acids. The effect of antihypertensive treatment was evaluated after monotherapy with either angiotensin converting enzyme inhibition or calcium-channel blockade in hypertension.

RESULTS

Plasma amylin was increased in hypertension (P= 0.027), and body mass index was a strong predictor of increased circulating amylin (P = 0.0001). Plasma amylin and plasma renin activity were not correlated (P = 0.395), and effective antihypertensive monotherapy with either angiotensin converting enzyme inhibition or calcium-channel blockade did not affect either amylin (P = 0.87-0.97) or insulin (P= 0.55-0.59). Among normotensive individuals, those at genetic risk of hypertension (with positive family history) already had increased concentrations of amylin (P< 0.001), despite exhibiting no difference in blood pressure or body mass index compared with the family-history-negative group; however, among normotensive individuals, both family history (P = 0.043) and body mass index (P= 0.0059) were significant predictors of increased concentrations of amylin. By maximum likelihood analysis, plasma amylin was distributed heterogeneously in the normotensive individuals, with two modes best explaining the distribution (chi2 = 77.4, P< 0.001), and family-history-positive individuals completely accounting for the upper mode (chi2 = 4.63, P = 0.031). Family-history-positive normotensive individuals showed greater plasma amylin concentrations both before and during beta-cell stimulation by amino acid infusion (P = 0.014). Black (n = 111) and white (n = 172) individuals did not differ in mean (P = 0.946) or variance (P = 0.172) of plasma amylin concentrations.

CONCLUSIONS

These results suggest that plasma amylin concentration is in part determined by heredity. Both basal and stimulated plasma amylin excess may identify a subgroup of individuals bearing an inherited predisposition to hypertension. Measurement of amylin might identify a useful 'intermediate phenotype' in the genetic analysis of essential hypertension and its relationship to insulin resistance.

Lifetime overweight status in relation to serial changes in body composition and risk factors for cardiovascular disease: The Fels Longitudinal Study

OBJECTIVE

The aims were to determine if 1) individuals who became and maintained overweight during their entire lifetime differ from those who were never-overweight in terms of annual changes in adiposity and concurrent changes in cardiovascular disease (CVD) risk factors; 2) the changes and their relationships to each other varied between these groups or by sex within the groups; and 3) alcohol usage, smoking habits, and level of physical activity differed between groups.

RESEARCH METHODS AND PROCEDURES

Data from 16,315 examinations of 414 individuals were utilized to assess lifetime overweight (body mass index [BMI] > 25 kg/m2) status. A regressive analytic approach was used to determine the average annual changes for each individual over an adult serial interval ranging from 4 to 20 years.

RESULTS

Men and women who have become and maintained overweight have higher blood pressure and a poorer lipid/lipoprotein risk profile than those who have never been overweight. There is an accelerated deterioration in the atherogenic profile of overweight men and women as indicated by annual changes in CVD risk factors about double that of their never-overweight counterparts. In women, increased risk is derived from increasing systolic and diastolic blood pressure, whereas in men the increased risk comes not only from increasing diastolic blood pressure but also cholesterol, triglycerides, and low-density lipoprotein cholesterol levels and, to a lesser extent, decreasing high-density lipoprotein cholesterol.

DISCUSSION

The reduced physical activity observed in the overweight adults may be related to their accumulation of adipose tissue at a rate about double their never-overweight counterparts, and this may be driving the higher rate of increase of CVD risk factors in the overweight groups.

Ethnic differences in the responsiveness of adipocyte lipolytic activity to insulin

OBJECTIVE

The goal of this study was to quantify differences in lipid metabolism and insulin sensitivity in black and white subjects to explain ethnic clinicopathological differences in type 2 diabetes.

RESEARCH METHODS AND PROCEDURES

The in vitro lipolytic activity of adipocytes isolated from obese black and white women was measured in the presence of insulin and isoproterenol. Insulin resistance was assessed in vivo using the euglycemic hyperinsulinemic clamp technique.

RESULTS

Fasting plasma levels of insulin and nonesterified fatty acid (NEFA) in black and white women were 67 +/- 5 pM vs. 152 +/- 20 pM (p < 0.01) and 863 +/- 93 microM vs. 412 +/- 34 microM (p < 0.01), respectively. Euglycemic hyperinsulinemic clamp studies showed that obese black subjects were more insulin-resistant than their white counterparts (glucose infusion rates: 1.3 +/- 0.2 vs. 2.2 +/- 0.3 mg/kg per min; p < 0.05). Isolated adipocytes from white women were more responsive to insulin than those from black women with 0.7 nM insulin causing a 55 +/- 4% inhibition of isoproterenol-stimulated lipolysis compared with 27 +/- 10% in black women (p < 0.05).

DISCUSSION

The low responsiveness of adipocyte lipolytic activity to insulin in black women in the presence of a relative insulinopenia may account for the high plasma NEFA levels seen in these women, which may, in turn, account for their higher in vivo insulin resistance. High NEFA levels may also contribute to the low insulin secretory activity observed in the obese black females. These data suggest that the pathogenesis of insulin resistance and type 2 diabetes within the black obese community is strongly influenced by their adipocyte metabolism.

Inositol phosphoglycans in diabetes and obesity: urinary levels of IPG A-type and IPG P-type, and relationship to pathophysiological changes

Measurements have been made, in adult male diabetic patients and control subjects, of the urinary content of inositol phosphoglycans (IPGs), the IPG A-type and IPG P-type forms, which, among other actions, regulate pathways of glucose utilization, lipogenesis, triglyceride formation, and pyruvate dehydrogenase (PDH) activity. Urine samples from the entire diabetic group showed a 2- to 3-fold increase in IPG A-type, and a fall in the IPG P-type:IPG A-type ratio relative to the control group. Subdivision of the diabetic patients into lean IDDM and obese NIDDM groups revealed significant differences in the IPG P-type:IPG A-type ratio between these groups, this ratio decreasing with increases in the body mass index (BMI). Analysis of the relationships among IPGs and HbA1, blood pressure, and BMI indicated that a fall in the IPG P-type:IPG A-type ratio correlated with a rise in the HbA1 (indicative of impaired glycemic control), with increased systolic blood pressure and increased obesity, all factors linked to Syndrome X. There was a parallism between the profile of the IPG P-type:IPG A-type ratio and the well-established pattern of insulin resistance and BMI. In vitro studies of the effects of alterations in the IPG P-type:IPG A-type ratio on the activation of the pyruvate dehydrogenase complex (PDH complex) at the PDH phosphatase reaction demonstrated that IPG A-type forms antagonized the stimulation of the PDH phosphatase by IPG P-type forms, thus having a negative effect on the conversion of PDH to the active, dephosphorylated, form. This observation could provide a mechanism whereby the shifts in the IPG P-type:IPG A-type ratio reported above could change the metabolic pattern from one directed to glucose oxidation to one more directed toward energy conservation and lipid storage.

Obesity and hypertension

Substantial evidence from epidemiological data supports a link between obesity and hypertension. However, the relationship between the two disorders is not straightforward and most likely represents an interaction of demographic, genetic, hormonal, renal, and hemodynamic factors. Age, race, and sex also modulate the strength of the association between obesity and hypertension. Hyperinsulinemia, which is characteristic of obesity, can contribute to the probability of developing hypertension by activating the sympathetic nervous system (SNS) and by causing sodium retention. The pressor effect of insulin in obesity may be further enhanced by the observation that its vasodilator action can be blunted in obese subjects. Preliminary data have shown that leptin, whose levels are increased in most obese individuals, can contribute to hypertension in obesity through its effects on insulin, SNS, and sodium excretion. The kidney may also have a role in the pathophysiology of hypertension in obesity. Abnormal renal sodium handling coupled with structural changes in the kidney of an obese patient can raise blood pressure. In addition, obesity is associated with distinct cardiovascular hemodynamic alterations and development of eccentric myocardial hypertrophy. Most of these obesity-associated abnormalities, as well as hypertension itself, can be reversed by weight loss. Furthermore, weight loss can prevent, or at least delay, the development of hypertension in patients with high-normal blood pressure. Weight reduction should be the first-line treatment in every obese hypertensive patient. However, the majority of patients will need pharmacologic intervention in conjunction with weight loss. Selection of antihypertensive agents in the overweight patient should take into account the mechanisms leading to hypertension and the metabolic abnormalities that characterize the obese patient.

Effect of insulin treatment on smooth muscle contractility and endothelium-dependent relaxation in rat aortae from established STZ-induced diabetes

1. This study involved the chronic administration of low or high insulin to rats with established streptozotocin (STZ)-induced diabetes. We studied the effect of such treatment on smooth muscle contractility and endothelium-dependent relaxation using aortic strips. 2. Aortae from diabetic rats, but not those from high-insulin-treated diabetic rats, showed an impaired endothelium-dependent in response to acetylcholine (ACh) by comparison with untreated controls. 3. Isotonic high K+-induced contractility was impaired in diabetic aortae. This impairment was prevented by high-insulin treatment. 4. Noradrenaline (NA)-induced contractility was enhanced in aortae from high-insulin-treated diabetic rats, but not in those from untreated diabetic or low-insulin treated diabetic rats. 5. In the combined presence of the nitric oxide inhibitor N(G)-nitro-L-arginine and the cyclo-oxygenase inhibitor indomethacin, NA-induced contractility was significantly greater in aortae from high-insulin-treated diabetic rats than in those from controls or untreated diabetic rats. 6. An increased expression of the mRNA for the alpha1D and alpha1B adrenergic receptors was found in aortae from high-insulin-treated diabetic rats. 7. These results demonstrate that in rats with established STZ-induced diabetes, high-insulin treatment prevents the development of an impaired endothelium-dependent relaxation in the aorta, and that such treatment enhances NA-induced contractility. This enhancement may be related to an upregulation in the expression of the mRNA for the alpha1B or alpha1D adrenergic receptor that is secondary to the hyperinsulinaemia.

Regulation of hepatic enzymes and insulin levels in offspring of rat dams fed a reduced-protein diet

We have hypothesized that permanent changes caused by poor growth during early development due to maternal malnutrition may be exacerbated by overnutrition of offspring in later life. To test this hypothesis, rats were exposed to a maternal 20% protein diet or an isocaloric 8% protein diet during fetal and postnatal life. All offspring were weaned onto laboratory chow. At 6 wk, rats were fed laboratory chow or a highly palatable diet (high fat and high calorie with adequate protein) and studied at 12 wk after a 48-h fast. The highly palatable diet resulted in excess weight gain and higher plasma insulin levels in all animals. Plasma insulin concentrations were significantly increased in male offspring of dams fed a reduced-protein diet compared with male offspring of dams fed an adequate-protein diet, but no differences were observed between the female offspring. The key hepatic enzymes of glucose homeostasis programmed in offspring of protein-restricted rat dams retained the ability to respond to overnutrition during adult life. In these offspring, however, the enzymes were regulated around a "set point" that was different from that in the controls.

The effect of fasting and vitamin E on insulin action in obese type 2 diabetes mellitus

The influence of either short-term fasting or vitamin E administration on insulin action was studied in two groups of obese Type 2 diabetic patients. Twelve patients underwent 7 days of fasting (group A), whereas 600 mg of vitamin E was administered daily during 3 months in 9 diabetic patients (group B). Insulin action was examined by using hyperinsulinemic isoglycemic clamps (insulin infusion rate, 1.0 mU/kg/min) and insulin receptors on erythrocytes before and after respective regimens. An increase of glucose disposal rate (29.5 +/- 8.9 vs. 24.0 +/- 7.5 mumol/kg/min, p < 0.01) and an increase of metabolic clearance rate of glucose (4.0 +/- 2.5 vs. 2.3 +/- 0.9 mL/kg/min, p < 0.01) were observed in group A after fasting. On the contrary, decreases of glucose disposal rate (21.3 +/- 8.5 vs. 26.6 +/- 9.8 mumol/kg/min, p < 0.02), metabolic clearance rate of glucose (2.9 +/- 0.8 vs. 3.7 +/- 1.7 mL/kg/min, p < 0.05), and insulin receptor number (p < 0.01) were found after vitamin E administration as compared with pretreated values. A worsening of diabetes control as observed by an increase of HbA1C (p < 0.01) was present in the latter group. In summary, we found an improvement of insulin action after short-term fasting in contrast with the worsening of metabolic parameters after vitamin E administration in obese Type 2 diabetic patients.

Effects on energy utilization of a beta3-adrenergic agonist in rats fed on a cafeteria diet

The antiobesity potential of a new beta3-adrenergic agonist (Trecadrine) was assessed in a cafeteria model of obesity through body composition, thermogenesis and oxygen consumption indicators. Animals fed on a cafeteria diet for 75 days increased body weight and fat content, while muscle mass as a percentage of body weight was reduced in relation to control fed rats. In addition, in vitro brown adipose tissue (BAT) and white adipose tissue (WAT) oxygen consumption was increased in these obese animals as compared with controls. Trecadrine administration reduced weight gain, BAT and WAT stores as well as the respiratory quotient, which was accompanied by an increase in WAT and BAT oxygen consumption and rectal temperature. Moreover, muscle mass as a percentage of body weight maintained the same values as non-obese animals, while an increase in absolute muscle weight was found in Trecadrine-treated obese rats. However, liver weights and in vitro oxygen consumption remained unaltered after cafeteria feeding and Trecadrine administration. Since chronic administration of Trecadrine had no effect on food intake, the stimulation of thermogenesis and oxygen consumption by the beta3-adrenergic agonist in white and brown adipose tissue are apparently responsible for the rise in energy expenditure as well as for the lower weight gain and fat deposition in obese treated rats. Thus, Trecadrine exhibits some promise as a potential treatment for obesity.