Hypertension, insulin resistance, and the metabolic syndrome

Associations of renin-angiotensin system inhibitor use with brain insulin signaling and neuropathology

OBJECTIVE

To examine the associations of renin-angiotensin system (RAS) inhibitor use with postmortem brain insulin signaling and neuropathology.

METHODS

Among Religious Orders Study participants, 150 deceased and autopsied older individuals (75 with diabetes matched to 75 without by age at death, sex, and education) had measurements of insulin receptor substrate-1 (IRS-1) and RAC-alpha serine/threonine protein kinase (AKT1) collected in the prefrontal cortex using ELISA and immunohistochemistry. Alzheimer's disease (AD), brain infarcts, and cerebral vessel pathology data were assessed by systematic neuropathologic evaluations. RAS inhibitor use was determined based on visual inspection of medication containers during study visits. The associations of RAS inhibitor use with brain insulin signaling measures and neuropathology were examined using adjusted regression analyses.

RESULTS

Of the 90 RAS inhibitor users (54 with diabetes), 65 had used only angiotensin-converting enzyme inhibitors, 11 only angiotensin II receptor blockers, and 14 used both. RAS inhibitor use was associated with lower pT308AKT1/total AKT1, but not with pS307IRS-1/total IRS-1 or the density of cells stained positive for pS616 IRS-1. RAS inhibitor use was not associated with the level of global AD pathology or amyloid beta burden, but it was associated with a lower tau-neurofibrillary tangle density. Additionally, we found a significant interaction between diabetes and RAS inhibitors on tangle density. Furthermore, AKT1 phosphorylation partially mediated the association of RAS inhibitor use with tau tangle density. Lastly, RAS inhibitor use was associated with more atherosclerosis, but not with other cerebral blood vessel pathologies or cerebral infarcts.

INTERPRETATION

Late-life RAS inhibitor use may be associated with lower brain AKT1 phosphorylation and fewer neurofibrillary tangles.

Characteristic Gut Bacteria in High Barley Consuming Japanese Individuals without Hypertension

BACKGROUND

Barley, a grain rich in soluble dietary fiber β-glucan, is expected to lower blood pressure. Conversely, individual differences in its effects on the host might be an issue, and gut bacterial composition may be a determinant.

METHODS

Using data from a cross-sectional study, we examined whether the gut bacterial composition could explain the classification of a population with hypertension risks despite their high barley consumption. Participants with high barley intake and no occurrence of hypertension were defined as "responders" (n = 26), whereas participants with high barley intake and hypertension risks were defined as "non-responders" (n = 39).

RESULTS

16S rRNA gene sequencing revealed that feces from the responders presented higher levels of Faecalibacterium, Ruminococcaceae UCG-013, Lachnospira, and Subdoligranulum and lower levels of Lachnoclostridium and Prevotella 9 than that from non-responders. We further created a machine-learning responder classification model using random forest based on gut bacteria with an area under the curve value of 0.75 for estimating the effect of barley on the development of hypertension.

CONCLUSIONS

Our findings establish a link between the gut bacteria characteristics and the predicted control of blood pressure provided by barley intake, thereby providing a framework for the future development of personalized dietary strategies.

Pathogenesis of Hypertension in Metabolic Syndrome: The Role of Fructose and Salt

Metabolic syndrome is manifested by visceral obesity, hypertension, glucose intolerance, hyperinsulinism, and dyslipidemia. According to the CDC, metabolic syndrome in the US has increased drastically since the 1960s leading to chronic diseases and rising healthcare costs. Hypertension is a key component of metabolic syndrome and is associated with an increase in morbidity and mortality due to stroke, cardiovascular ailments, and kidney disease. The pathogenesis of hypertension in metabolic syndrome, however, remains poorly understood. Metabolic syndrome results primarily from increased caloric intake and decreased physical activity. Epidemiologic studies show that an enhanced consumption of sugars, in the form of fructose and sucrose, correlates with the amplified prevalence of metabolic syndrome. Diets with a high fat content, in conjunction with elevated fructose and salt intake, accelerate the development of metabolic syndrome. This review article discusses the latest literature in the pathogenesis of hypertension in metabolic syndrome, with a specific emphasis on the role of fructose and its stimulatory effect on salt absorption in the small intestine and kidney tubules.

TyGIS: improved triglyceride-glucose index for the assessment of insulin sensitivity during pregnancy

Background

The triglyceride-glucose index (TyG) has been proposed as a surrogate marker of insulin resistance, which is a typical trait of pregnancy. However, very few studies analyzed TyG performance as marker of insulin resistance in pregnancy, and they were limited to insulin resistance assessment at fasting rather than in dynamic conditions, i.e., during an oral glucose tolerance test (OGTT), which allows more reliable assessment of the actual insulin sensitivity impairment. Thus, first aim of the study was exploring in pregnancy the relationships between TyG and OGTT-derived insulin sensitivity. In addition, we developed a new version of TyG, for improved performance as marker of insulin resistance in pregnancy.

Methods

At early pregnancy, a cohort of 109 women underwent assessment of maternal biometry and blood tests at fasting, for measurements of several variables (visit 1). Subsequently (26 weeks of gestation) all visit 1 analyses were repeated (visit 2), and a subgroup of women (84 selected) received a 2 h-75 g OGTT (30, 60, 90, and 120 min sampling) with measurement of blood glucose, insulin and C-peptide for reliable assessment of insulin sensitivity (PREDIM index) and insulin secretion/beta-cell function. The dataset was randomly split into 70% training set and 30% test set, and by machine learning approach we identified the optimal model, with TyG included, showing the best relationship with PREDIM. For inclusion in the model, we considered only fasting variables, in agreement with TyG definition.

Results

The relationship of TyG with PREDIM was weak. Conversely, the improved TyG, called TyGIS, (linear function of TyG, body weight, lean body mass percentage and fasting insulin) resulted much strongly related to PREDIM, in both training and test sets (R² > 0.64, p < 0.0001). Bland–Altman analysis and equivalence test confirmed the good performance of TyGIS in terms of association with PREDIM. Different further analyses confirmed TyGIS superiority over TyG.

Conclusions

We developed an improved version of TyG, as new surrogate marker of insulin sensitivity in pregnancy (TyGIS). Similarly to TyG, TyGIS relies only on fasting variables, but its performances are remarkably improved than those of TyG.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01649-8.

Hypertension in obese children is associated with vitamin D deficiency and serotonin dysregulation

Background

Obesity and hypertension represent serious health issues affecting the pediatric population with increasing prevalence. Hypovitaminosis D has been suggested to be associated with arterial hypertension. Serotonin by modulating nitric oxide synthase affect blood pressure regulation. The biological mechanism by which vitamin D specifically regulates serotonin synthesis was recently described. The aim of this paper is to determine the associations between vitamin D, serotonin, and blood pressure in obese children.

Methods

One hundred and seventy-one children were enrolled in the prospective cross-sectional study. Two groups of children divided according to body mass index status to obese (BMI ≥95th percentile; n = 120) and non-obese (n = 51) were set. All children underwent office and ambulatory blood pressure monitoring and biochemical analysis of vitamin D and serotonin. Data on fasting glucose, insulin, HOMA, uric acid, and complete lipid profile were obtained in obese children.

Results

Hypertension was found only in the group of obese children. Compared to the control group, obese children had lower vitamin D and serotonin, especially in winter. The vitamin D seasonality and BMI-SDS were shown as the most significant predictors of systolic blood pressure changes, while diastolic blood pressure was predicted mostly by insulin and serotonin. The presence of hypertension and high-normal blood pressure in obese children was most significantly affected by vitamin D deficiency and increased BMI-SDS.

Conclusions

Dysregulation of vitamin D and serotonin can pose a risk of the onset and development of hypertension in obese children; therefore, their optimization together with reducing body weight may improve the long-term cardiovascular health of these children.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03337-8.

Nrf2-interacting nutrients and COVID-19: time for research to develop adaptation strategies

There are large between- and within-country variations in COVID-19 death rates. Some very low death rate settings such as Eastern Asia, Central Europe, the Balkans and Africa have a common feature of eating large quantities of fermented foods whose intake is associated with the activation of the Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) anti-oxidant transcription factor. There are many Nrf2-interacting nutrients (berberine, curcumin, epigallocatechin gallate, genistein, quercetin, resveratrol, sulforaphane) that all act similarly to reduce insulin resistance, endothelial damage, lung injury and cytokine storm. They also act on the same mechanisms (mTOR: Mammalian target of rapamycin, PPARγ:Peroxisome proliferator-activated receptor, NFκB: Nuclear factor kappa B, ERK: Extracellular signal-regulated kinases and eIF2α:Elongation initiation factor 2α). They may as a result be important in mitigating the severity of COVID-19, acting through the endoplasmic reticulum stress or ACE-Angiotensin-II-AT₁R axis (AT₁R) pathway. Many Nrf2-interacting nutrients are also interacting with TRPA1 and/or TRPV1. Interestingly, geographical areas with very low COVID-19 mortality are those with the lowest prevalence of obesity (Sub-Saharan Africa and Asia). It is tempting to propose that Nrf2-interacting foods and nutrients can re-balance insulin resistance and have a significant effect on COVID-19 severity. It is therefore possible that the intake of these foods may restore an optimal natural balance for the Nrf2 pathway and may be of interest in the mitigation of COVID-19 severity.

Decreased Homocysteine Trans-Sulfuration in Hypertension With Hyperhomocysteinemia: Relationship With Insulin Resistance

CONTEXT

Homocysteine is an independent cardiovascular risk factor and is elevated in essential hypertension. Insulin stimulates homocysteine catabolism in healthy individuals. However, the mechanisms of hyperhomocysteinemia and its relationship with insulin resistance in essential hypertension are unknown.

OBJECTIVE

To investigate whole body methionine and homocysteine kinetics and the effects of insulin in essential hypertension.

DESIGN AND SETTING

Eight hypertensive male subjects and six male normotensive controls were infused with l-[methyl-2H3,1-13C]methionine for 6 hours. In the last 3 hours a euglycemic, hyperinsulinemic clamp was performed. Steady-state methionine and homocysteine kinetics were determined in postabsorptive and hyperinsulinemic conditions.

RESULTS

Postabsorptive hypertensive subjects had elevated homocysteine concentrations (+30%, P = 0.035) and slightly (by 15% to 20%) but insignificantly lower methionine rates of appearance (Ras) (P = 0.07 to P = 0.05) and utilization for protein synthesis (P = 0.06) than postabsorptive normotensive controls. Hyperinsulinemia suppressed methionine Ra and protein synthesis, whereas it increased homocysteine trans-sulfuration, clearance, and methionine transmethylation (the latter only in the normotensive subjects). However, in the hypertensive subjects trans-sulfuration was significantly lower (P < 0.05) and increased ~50% less [by +1.59 ± 0.34 vs +3.45 ± 0.52 µmol/kg lean body mass (LBM) per hour, P < 0.005] than in normotensive controls. Homocysteine clearance through trans-sulfuration was ~50% lower in hypertensive than in normotensive subjects (P < 0.005). In the hypertensive subjects, insulin-mediated glucose disposal was ~45% lower (460 ± 44 vs 792 ± 67 mg/kg LBM per hour, P < 0.0005) than in normotensive controls and was positively correlated with the increase of trans-sulfuration (P < 0.0015).

CONCLUSIONS

In subjects with essential hypertension, hyperhomocysteinemia is associated with decreased homocysteine trans-sulfuration and probably represents a feature of insulin resistance.

Relationships between blood pressure and blood glucose among offspring of parents with type 2 diabetes: Prediction of incident dysglycemia in a biracial cohort

AIMS

We assessed blood pressure (BP) and blood glucose (BG) values in healthy subjects, and examined baseline BP as a predictor of incident prediabetes during follow-up.

METHODS

Participants in the Pathobiology of Prediabetes in a Biracial Cohort (POP-ABC) study underwent screening assessments (anthropometry, BP, OGTT) and were stratified into normal BP (NBP), prehypertension, or hypertension, and normal glucose regulation (NGR), prediabetes (IFG/IGT), or type 2 diabetes (T2D) status. NGR subjects who met all inclusion criteria were enrolled in a 5-yr prospective study, with the primary outcome of incident prediabetes.

RESULTS

We screened 602 adults (341 black, 261 white) and enrolled 343 (193 black, 150 white) for prospective follow-up. Systolic and diastolic BP correlated significantly with fasting and nonfasting BG (P=0.003-<0.0001). Compared to NGR group, more prediabetic subjects had prehypertension (42.5% vs. 36.2%) and fewer had NBP (35.9% vs. 48.6%) (P=0.009). During ~5years of follow-up, 26.3% of NBP and 35.7% of prehypertensive subjects developed prediabetes (P=0.02). Kaplan-Meier analysis showed higher probability of incident prediabetes among participants with prehypertension compared to NBP during ~5years of follow-up (P=0.0012).

CONCLUSIONS

In our biracial cohort, BP and BG values were significantly correlated, and BP status predicted incident prediabetes among initially normoglycemic individuals. These findings suggest co-evolution of factors involved in the dysregulation of BP and BG.

Metabolic syndrome in children and adolescents

Prevalence of metabolic syndrome in children and adolescents is increasing, in parallel with the increasing trends in obesity rates. Varying definitions of this syndrome have hindered the development of a consensus for the diagnostic criteria in the pediatric population. While pathogenesis of metabolic syndrome is not completely understood, insulin resistance and subsequent inflammation are thought to be among its main mechanistic underpinnings. Overweight and obesity are cardinal features, along with abnormal glucose metabolism, dyslipidemia, and hypertension. Other disorders associated with metabolic syndrome include fatty liver, polycystic ovarian syndrome (PCOS), and pro-inflammatory states. Prevention and management of this condition can be accomplished with lifestyle modifications, behavioral interventions, pharmacological and surgical interventions as needed.

The association between tuberculosis and the development of insulin resistance in adults with pulmonary tuberculosis in the Western sub-district of the Cape Metropole region, South Africa: a combined cross-sectional, cohort study

BACKGROUND

The existence of a bi-directional relationship between tuberculosis (TB) and insulin resistance (IR)/diabetes has been alluded to in literature. Although diabetes has been linked to increased tuberculosis risk, the relationship between tuberculosis as a causative factor for IR remains unclear. The study aimed to determine if an association existed between tuberculosis and IR development in adults with newly diagnosed pulmonary tuberculosis at baseline. It was additionally aimed to document changes in IR status during TB follow-up periods.

METHODS

This cross-sectional study evaluated ambulatory participants at baseline for IR prevalence via anthropometry, biochemistry and diagnostic IR tests [homeostasis model assessment-IR (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI)]. A prospective cohort sub-section study was additionally performed on approximately half of the baseline study population, who were followed-up at two and five months whilst on tuberculosis treatment. Summary statistics, correlation co-efficients and appropriate analysis of variance were used to describe and analyse data. Participants were excluded if they presented with other forms of tuberculosis, were HIV-positive, obese or had any pre-disposing IR conditions such as diabetes or metabolic syndrome.

RESULTS

Fifty-nine participants were included from August 2013 until December 2014 (33.95 ± 12.02 years old; 81.4% male). IR prevalence was 25.4% at baseline, determined by a calculated HOMA-IR cut-off point of 2.477. Patients with IR were younger (p = 0.04). Although the difference between IR levels in participants between baseline and follow-up was not significant, a decrease was observed over time. The majority of participants (61.0%) presented with a normal BMI at baseline. Mean baseline values of fasting glucose were within normal ranges (4.82 ± 0.80 mmol/L), whereas increased mean CRP levels (60.18 ± 50.92 mg/L) and decreased mean HDL-cholesterol levels (males: 0.94 ± 0.88 mmol/L; females: 1.14 ± 0.88 mmol/L) were found.

CONCLUSIONS

The study found an association between tuberculosis and IR development in newly diagnosed pulmonary tuberculosis patients. Although not significant, IR levels decreased over time, which could be indicative of a clinical improvement. A high prevalence of IR amongst young tuberculosis patients therefore highlights the need for early identification in order to facilitate a reversal of IR and prevent possible IR-related complications.

The impact of triglycerides on glucose tolerance: Lipotoxicity revisited

Elevated plasma triglycerides (TGs) are early key features of conditions associated with a dysregulation in glucose metabolism and may predict the development of type 2 diabetes (T2D) over time. Although the acute ingestion of lipid, either mixed with or shortly before the meal, is neutral or slightly beneficial on glucose tolerance, a short-term increase in plasma TGs induced by either an i.v. lipid infusion or a high-fat diet produces a deterioration of glucose control. Accordingly, chronic lowering of plasma TGs by fibrates improves glucose homeostasis and may also prevent T2D. The chronic effects of the elevation of dietary lipid intake are less clear, particularly in humans, being the quality of fat probably more important than total fat intake. Although on the bases of the available experimental and clinical evidence it cannot be easily disentangled, with respect to elevated non-esterified fatty acids (NEFA) the relative contribution of elevated TGs to glucose homeostasis disregulation seems to be greater and also more plausible. In conclusion, although the association between elevated plasma TGs and impaired glucose tolerance is commonly considered not causative or merely a consequence of NEFA-mediated lipotoxicity, the available data suggest that TGs per se may directly contribute to disorders of glucose metabolism.

Long-Term Feeding of Chitosan Ameliorates Glucose and Lipid Metabolism in a High-Fructose-Diet-Impaired Rat Model of Glucose Tolerance

This study was designed to investigate the effects of long-term feeding of chitosan on plasma glucose and lipids in rats fed a high-fructose (HF) diet (63.1%). Male Sprague-Dawley rats aged seven weeks were used as experimental animals. Rats were divided into three groups: (1) normal group (normal); (2) HF group; (3) chitosan + HF group (HF + C). The rats were fed the experimental diets and drinking water ad libitum for 21 weeks. The results showed that chitosan (average molecular weight was about 3.8 × 10⁵ Dalton and degree of deacetylation was about 89.8%) significantly decreased body weight, paraepididymal fat mass, and retroperitoneal fat mass weight, but elevated the lipolysis rate in retroperitoneal fats of HF diet-fed rats. Supplementation of chitosan causes a decrease in plasma insulin, tumor necrosis factor (TNF)-α, Interleukin (IL)-6, and leptin, and an increase in plasma adiponectin. The HF diet increased hepatic lipids. However, intake of chitosan reduced the accumulation of hepatic lipids, including total cholesterol (TC) and triglyceride (TG) contents. In addition, chitosan elevated the excretion of fecal lipids in HF diet-fed rats. Furthermore, chitosan significantly decreased plasma TC, low-density lipoprotein cholesterol (LDL-C), very-low-density lipoprotein cholesterol (VLDL-C), the TC/high-density lipoprotein cholesterol (HDL-C) ratio, and increased the HDL-C/(LDL-C + VLDL-C) ratio, but elevated the plasma TG and free fatty acids concentrations in HF diet-fed rats. Plasma angiopoietin-like 4 (ANGPTL4) protein expression was not affected by the HF diet, but it was significantly increased in chitosan-supplemented, HF-diet-fed rats. The high-fructose diet induced an increase in plasma glucose and impaired glucose tolerance, but chitosan supplementation decreased plasma glucose and improved impairment of glucose tolerance and insulin tolerance. Taken together, these results indicate that supplementation with chitosan can improve the impairment of glucose and lipid metabolism in a HF-diet-fed rat model.

Milk-derived tripeptides IPP (Ile-Pro-Pro) and VPP (Val-Pro-Pro) promote adipocyte differentiation and inhibit inflammation in 3T3-F442A cells

Milk derived tripeptides IPP (Ile-Pro-Pro) and VPP (Val-Pro-Pro) have shown promise as anti-hypertensive agents due to their inhibitory effects on angiotensin converting enzyme (ACE). Due to the key inter-related roles of hypertension, chronic inflammation and insulin resistance in the pathogenesis of metabolic syndrome, there is growing interest in investigating established anti-hypertensive agents for their effects on insulin sensitivity and inflammation. In this study, we examined the effects of IPP and VPP on 3T3-F442A murine pre-adipocytes, a widely used model for studying metabolic diseases. We found that both IPP and VPP induced beneficial adipogenic differentiation as manifested by intracellular lipid accumulation, upregulation of peroxisome proliferator-activated receptor gamma (PPARγ) and secretion of the protective lipid hormone adiponectin by these cells. The observed effects were similar to those induced by insulin, suggesting potential benefits in the presence of insulin resistance. IPP and VPP also inhibited cytokine induced pro-inflammatory changes such as reduction in adipokine levels and activation of the nuclear factor kappa B (NF-κB) pathway. Taken together, our findings suggest that IPP and VPP exert insulin-mimetic adipogenic effects and prevent inflammatory changes in adipocytes, which may offer protection against metabolic disease.

Relation of the rs6923761 gene variant in glucagon-like peptide 1 receptor to metabolic syndrome in obese subjects

BACKGROUND

The role of glucagon-like peptide 1 (GLP-1) variants in metabolic syndrome (MS) and its components remains unclear in obese subjects.

OBJECTIVE

The aim of our study was to evaluate the relationship of rs6923761 with MS and its components in obese subjects.

DESIGN

A population of 1,122 obese subjects was analyzed in a cross-sectional survey. To estimate the prevalence of MS, we considered the definitions of the Adult Treatment Panel III.

RESULTS

Five hundred and forty-eight patients (48.8%) had the GG genotype (wild-type group), whereas 487 patients (43.4%) had the GA genotype and 87 patients (7.8%) the AA genotype. The mean age was 48.9 ± 12.8 years. The prevalence of MS was 47.4% (532 patients), and 52.6% of patients had no MS (n = 590). The odds ratio of MS for the wild-type versus the mutant genotype was 1.02, with a 95% confidence interval of 0.88-1.12. Body mass index, weight, fat mass, waist circumference, and waist to hip ratio were lower in the mutant than in the wild-type group in patients with and without MS.

CONCLUSION

The GLP-1 receptor variant rs6923761 was found to be associated with decreased weight and anthropometric parameters in A allele carriers with and without MS. MS or its components were not associated with this polymorphism in obese adults.

Relation of the rs9939609 gene variant in FTO with metabolic syndrome in obese female patients

OBJECTIVES

Common polymorphisms of the fat mass and obesity associated gene (FTO) have been linked to obesity and diabetes mellitus type 2 in some populations. The aim of our study was to analyze the relationship of the rs9939609 FTO gene polymorphism with metabolic syndrome and its components.

MATERIAL AND METHODS

A population of 457 obese Caucasian females was analyzed in a cross-sectional survey. To estimate the prevalence of Metabolic Syndrome, the definitions of the ATPIII were considered. Genotype of FTO gene polymorphism (rs9939609) was studied.

RESULTS

One hundred and thirty patients (28.4%) had the genotype TT (wild group), whereas 227 patients (49.7%) had the genotype TA and 100 patients (21.9%) had the genotype AA. Prevalence of metabolic syndrome (MS) with ATP III definition was 40.7% (186 patients) and 59.3% patients had no MS (n = 271). Prevalence of mutant FTO genotypes was similar in patients with metabolic syndrome (27.4% wild genotype and 72.6% mutant genotype) and without metabolic syndrome (29.2% wild genotype and 70.8% mutant genotype).Odds ratio of metabolic syndrome in wild vs mutant genotype was 1.04 (95% CI: 0.87-1.22). Insulin levels (13.9±6.3 mUI/L vs. 12.6 ± 3.4 mUI/L; p<0.05), HOMA-R (3.3 ± 1.6 vs. 2.8 ± 1.4; p < 0.05) and triglycerides concentrations (110.8 ± 27.3 mg/dl vs. 103.1 ± 47.3 mg/dl; p < 0.05) were lower in the mutant type group than the wild type group in patients without metabolic syndrome.

CONCLUSION

The FTO gene polymorphism (rs9939609) was found to be associated with increased insulin resistance, insulin and triglyceride levels in obese females with TT variant and without metabolic syndrome. MS or its components were not associated with this polymorphism in obese females.

The endothelium in diabetes: its role in insulin access and diabetic complications

The vascular endothelium has been identified as an important component in diabetes-associated complications, which include many cardiovascular disorders such as atherosclerosis, hypertension and peripheral neuropathy. Additionally, insulin's actions on the endothelium are now seen as a major factor in the metabolic effects of the hormone by increasing access to insulin sensitive tissues. Endothelial function is impaired in diabetes, obesity, and the metabolic syndrome, which could reduce insulin access to the tissue, and thus reduce insulin sensitivity independently of direct effects at the muscle cell. As such, the endothelium is a valid target for treatment of both the impaired glucose metabolism in diabetes, as well as the vascular based complications of diabetes. Here we review the basics of the endothelium in insulin action, with a focus on the skeletal muscle as insulin's major metabolic organ, and how this is affected by diabetes. We will focus on the most recent developments in the field, including current treatment possibilities.

Relationship of -55C/T polymorphism of uncoupling protein 3 (UCP3) gene with metabolic syndrome by ATP III classification

BACKGROUND AND AIMS

The relation of -55C/T polymorphism of uncoupling protein 3 (UCP3) with metabolic syndrome (MS) has been evaluated only in one previous study with contradictory results. The aim of our study was to investigate the association of -55C/T polymorphism of UCP3 gene with MS.

DESIGN

A population of 817 obese Caucasian patients was analyzed in a cross-sectional survey. Genotype of UCP3 gene -55C/T was studied. To estimate the prevalence of MS , the definitions of the ATPIII were considered.

RESULTS

Five hundred and ninety-four patients (72.7%) had the genotype -55CC (wild group), whereas 223 patients (27.3%) had the genotype -55C/T. Genotype -5TT was not detected. Prevalence of mutant UCP genotypes was similar in patients with MS (75.7% wild genotype and 24.3% mutant genotype) and without MS (69.7% wild genotype and 30.3% mutant genotype). Odds ratio of MS wild vs. mutant genotype was 1.17 CI 95%: 0.99-1.38). Total cholesterol and low density lipoprotein (LDL) cholesterol concentrations were lower in mutant-type group than wild-type group in patients with MS. No differences in other parameters were detected between genotypes in the same group of MS.

CONCLUSION

-55C/T UCP polymorphism is not major risk factor for the MS. However, in mutant group of -55CC UCP3 gene in patients with MS, total cholesterol and LDL cholesterol were lower than wild-type patients.

Hyperinsulinemia and insulin resistance is associated with low T₃/T₄ ratio in pre diabetic euthyroid Pakistani subjects

OBJECTIVE

To investigate the relationship of thyroid hormones in glucose homeostasis in impaired glucose-tolerant subjects with normal thyroid functions.

METHODS

Cross-sectional analysis was carried out in (n=260) impaired glucose-tolerant (IGT) and normal glucose-tolerant (NGT) subjects. Thyrotropin (TSH), total triiodothyronine (TT₃), total thyroxin (TT₄) free T₃ (fT₃), free T₄ (fT₄), and insulin were assessed by enzyme-linked immunoassays (ELISA). Fasting plasma glucose (FPG) and HbA1c were measured by glucose oxidase and low-pressure cation exchange chromatography. Homeostasis model of assessment (HOMA-IR) was employed to assess the level of insulin resistance; fT₃/fT₄ ratio was calculated. Anthropometric measurement and habits were recorded.

RESULTS

Marked hyperinsulinemia and insulin resistance were observed in IGT subjects. Serum TT₃ and fT₃ levels were significantly low in the IGT as compared to normal glucose-tolerant (NGT) controls. TT₄ and TSH were higher in IGT subjects as compared to control subjects. There was a significant positive correlation of TSH with BMI only in the control group (r=0.351; P<0.05). Correlation of insulin with TT₃, fT₃,and TSH was significant (P<0.05) in IGT subjects. A significant low fT₃/fT₄ ratio was observed in IGT subjects as compared to NGT subjects (P<0.01). In multiple regression analysis, TSH, TT₄ and fT₃ contributed significantly to the variance of fasting insulin and insulin resistance in IGT subjects.

CONCLUSION

Hyperinsulinemia and insulin resistance are associated with low T₃/T₄ ratio in pre-diabetic euthyroid Pakistani subjects.

The metabolic syndrome and risk of chronic kidney disease: pathophysiology and intervention strategies

Metabolic syndrome is characterized by a clustering of cardiovascular risk factors, including abdominal obesity, elevated blood pressure and glucose concentrations, and dyslipidemia. The presence of this clinical entity is becoming more pervasive throughout the globe as the prevalence of obesity increases worldwide. Moreover, there is increased recognition of the complications and mortality related to this syndrome. This paper looks to examine the link between metabolic syndrome and the development of chronic kidney disease.

Prevalence of metabolic syndrome among human immunodeficiency virus-infected subjects is widely influenced by the diagnostic criteria

BACKGROUND

The aim of this study was to compare the prevalence of metabolic syndrome in human immunodeficiency virus (HIV)-infected patients treated with highly active antiretroviral therapy (HAART), using the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III), European Group for the Study of Insulin Resistance (EGIR), and International Diabetes Federation (IDF) definitions.

METHODS

A cross-sectional study was carried out with 159 consecutive adult HIV-infected subjects (120 males and 39 females) under HAART. Anthropometric and laboratory parameters were measured by standard methods. Hyperinsulinemia was defined by a fasting concentration >75th percentile of values obtained in healthy individuals (107.5 pmol/L).

RESULTS

The prevalence of ATP III-defined metabolic syndrome was 10.1%; it was 28.3% according to EGIR criteria and 15.1% using the IDF definition. The concordance between the definitions was low (kappa coefficient ranging between 0.134 and 0.296). All subjects with EGIR-defined metabolic syndrome had hyperinsulinemia, but only 50% of those with ATP III-defined metabolic syndrome and 62.5% in the IDF metabolic syndrome population had hyperinsulinemia.

CONCLUSIONS

The inclusion of hyperinsulinemia as a criterion in the EGIR metabolic syndrome definition made it more discriminative than the ATP III definition, both in men and women, and than the IDF definition in men to identify metabolic syndrome in HIV-infected subjects under HAART.

Insulin resistance: a potential marker and risk factor for active tuberculosis?

Current tuberculosis control measures are focused on the prompt detection and treatment of active tuberculosis. Despite the measured success of this strategy, tuberculosis continues to be a public health issue of major significance around the world. This unwanted situation suggests the need to expand our control efforts by exploring specific markers for the disease. Insulin resistance is one such marker. Although insulin resistance has been implicated in various diseases, thus far, no attempt has been made to analyze what has proved to be a direct relationship between insulin resistance and Mycobacterium tuberculosis susceptibility. Several studies have shown the role of insulin not only in cellular metabolism but also, more importantly, in phagocytosis of M. tuberculosis. Therefore, we hypothesize that insulin resistance can be considered a potential risk factor for active M. tuberculosis infection.

Association of metabolic syndrome with reduced central serotonergic activity

The aim of this study was to determine the differences between two groups of adolescents with metabolic syndrome (MetS) and normal controls in relation to brain serotonergic activity through intensity-dependent auditory-evoked potentials (IDAEPs) and plasma free fraction of L-tryptophan. Eighteen adolescents with MetS and thirteen controls were studied. Free fraction, bound and total plasma L-tryptophan, glucose, cholesterol, triglycerides, HDL-cholesterol, albumin and IDAEPs were determined. Glycemia, triglycerides were significantly elevated, and HDL-cholesterol in plasma was significantly reduced. Free fraction and free fraction/total L-tryptophan ratio were decreased. The slope of the amplitude/stimulus intensity function of the N1/P2 component significantly increased in adolescents with MetS. Decrease of free fraction of L-tryptophan in plasma and increase of the slope of the N1/P2 component suggest a low brain serotonin tone. Cortex responses are regulated by serotonergic innervations and may show a different behavior in young patients with MetS. Therefore, the slope of the N1/P2 component along with the free fraction of L-tryptophan in plasma, indicate that in adolescents with MetS the state of serotonergic brain activity is depressed and possibly related to psychiatric disorders.

Diet-induced obesity prevents interstitial dispersion of insulin in skeletal muscle

OBJECTIVE

Obesity causes insulin resistance, which has been interpreted as reduced downstream insulin signaling. However, changes in access of insulin to sensitive tissues such as skeletal muscle may also play a role. Insulin injected directly into skeletal muscle diffuses rapidly through the interstitial space to cause glucose uptake. When insulin resistance is induced by exogenous lipid infusion, this interstitial diffusion process is curtailed. Thus, the possibility exists that hyperlipidemia, such as that seen during obesity, may inhibit insulin action to muscle cells and exacerbate insulin resistance. Here we asked whether interstitial insulin diffusion is reduced in physiological obesity induced by a high-fat diet (HFD).

RESEARCH DESIGN AND METHODS

Dogs were fed a regular diet (lean) or one supplemented with bacon grease for 9-12 weeks (HFD). Basal insulin (0.2 mU x min(-1) x kg(-1)) euglycemic clamps were performed on fat-fed animals (n = 6). During clamps performed under anesthesia, five sequential doses of insulin were injected into the vastus medialis of one hind limb (INJ); the contralateral limb (NINJ) served as a control.

RESULTS

INJ lymph insulin showed an increase above NINJ in lean animals, but no change in HFD-fed animals. Muscle glucose uptake observed in lean animals did not occur in HFD-fed animals.

CONCLUSIONS

Insulin resistance induced by HFD caused a failure of intramuscularly injected insulin to diffuse through the interstitial space and failure to cause glucose uptake, compared with normal animals. High-fat feeding prevents the appearance of injected insulin in the interstitial space, thus reducing binding to skeletal muscle cells and glucose uptake.

Type 2 diabetes, cardiovascular disease, and the evolutionary paradox of the polycystic ovary syndrome: a fertility first hypothesis

Worldwide, the high prevalence of the Polycystic Ovary Syndrome (PCOS), a heritable cause of ovarian infertility, is an evolutionary paradox, which provides insight into the susceptibility of well-fed human populations to cardiovascular disease and diabetes. We propose that PCOS, Type 2 diabetes (T2D) and the Metabolic Syndrome are modern phenotypic expressions of a metabolic genotype attuned to the dietary and energetic conditions of the Pleistocene. This metabolic "Fertility First" rather than "Thrifty" genotype persisted at high prevalence throughout the entire agrarian period-from around 12,000 years ago until 1800 AD-primarily, we contend, because it conferred a fertility advantage in an environment defined by chronic and often severe seasonal food shortage. Conversely, we argue that genetic adaptations to a high carbohydrate, low protein agrarian diet, with increased sensitivity to insulin action, were constrained because these adaptations compromised fertility by raising the lower bound of body weight and energy intake optimal for ovulation and reproduction. After 1800, the progressive attainment of dietary energy sufficiency released human populations from this constraint. This release, through the powerful mechanism of fertility selection, increased, in decades rather than centuries, the prevalence of a genotype better suited to carbohydrate metabolism. This putative mechanism for rapid and recent human evolution can explain the lower susceptibility to T2D of today's Europid populations. This hypothesis predicts that the increasing rates of diabetes and cardiovascular disease, which typically accompany economic development, will be tempered by natural, but particularly fertility, selection against the conserved ancestral genotypes that currently underpin them.

The improvement of hypertension by probiotics: effects on cholesterol, diabetes, renin, and phytoestrogens

Probiotics are live organisms that are primarily used to improve gastrointestinal disorders such as diarrhea, irritable bowel syndrome, constipation, lactose intolerance, and to inhibit the excessive proliferation of pathogenic intestinal bacteria. However, recent studies have suggested that probiotics could have beneficial effects beyond gastrointestinal health, as they were found to improve certain metabolic disorders such as hypertension. Hypertension is caused by various factors and the predominant causes include an increase in cholesterol levels, incidence of diabetes, inconsistent modulation of renin and imbalanced sexual hormones. This review discusses the antihypertensive roles of probiotics via the improvement and/or treatment of lipid profiles, modulation of insulin resistance and sensitivity, the modulation of renin levels and also the conversion of bioactive phytoestrogens as an alternative replacement of sexual hormones such as estrogen and progesterone.

[Metabolic syndrome, its phenotypes, and insulin resistance by HOMA-IR]

The diagnosis of the metabolic syndrome (MS) according to the National Cholesterol Education Program Adult Treatment Panel III does not reflect necessarily the presence of insulin resistance (IR), a potential therapeutical target for type 2 diabetes and cardiovascular disease prevention. Based on previous prevalence data, a cross-sectional study was conducted to determine the HOMA-IR relationship to the MS and some associated abnormalities. HOMA-IR > was higher in individuals with the MS (2.8+/-1.6 vs. 1.8+/-1.4) (p < 0.001). HOMA-IR >or= 2.5 allied good specificity and sensitivity levels for the association of MS and IR. Hyperglycemia, hypertrigliceridemia, and abdominal obesity, the MS components best related to IR, were statistically associated with HOMA-IR > 2.5, but not hypertension neither low HDL-c. The demonstration that some of MS phenotypes or associated abnormalities were more predictive for IR could point out to the possibility of the use of the index as a marker of the presence of IR associated to MS.

Metabolic syndrome

Hirsutism is a finding that can lead to subsequent metabolic diagnoses such as the metabolic syndrome. Metabolic syndrome describes a cluster of cardiometabolic risk factors associated with overweight and obesity. Although it has been the subject of some controversy, perhaps due to the many definitions proposed by different health organizations, metabolic syndrome is clinically relevant in that it is a predictor of vascular risk, even independent of any associated type 2 diabetes. While various definitions may differ in precise cut-off points, they uniformly emphasize key pathophysiologic processes: visceral obesity, dyslipidemia, insulin resistance, and hypertension. Management of metabolic syndrome focuses on methods of reducing the component risk factors, and therapies thus target the above processes as well as controlling inflammation and the prothrombotic state. Treatments can include not only pharmacologic approaches but behavior modification as well.

Menopause, the metabolic syndrome, and mind-body therapies

Cardiovascular disease risk rises sharply with menopause, likely due to the coincident increase in insulin resistance and related atherogenic changes that together comprise the metabolic or insulin resistance syndrome, a cluster of metabolic and hemodynamic abnormalities strongly implicated in the pathogenesis and progression of cardiovascular disease. A growing body of research suggests that traditional mind-body practices such as yoga, tai chi, and qigong may offer safe and cost-effective strategies for reducing insulin resistance syndrome-related risk factors for cardiovascular disease in older populations, including postmenopausal women. Current evidence suggests that these practices may reduce insulin resistance and related physiological risk factors for cardiovascular disease; improve mood, well-being, and sleep; decrease sympathetic activation; and enhance cardiovagal function. However, additional rigorous studies are needed to confirm existing findings and to examine long-term effects on cardiovascular health.

Safety and effectiveness of rosiglitazone in type 2 diabetes patients with nonalcoholic Fatty liver disease

Background/Purpose

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease ranging in severity from steatosis to cirrhosis. Type 2 diabetes mellitus is a cause of primary NAFLD. Thiazolidinediones have been shown to enhance insulin sensitivity, improve glycemic control in type 2 diabetes patients and to improve the histologic markers of nonalcoholic steatohepatitis. This study aims to determine the safety and effectiveness of rosiglitazone in inadequately controlled type 2 diabetes patients with NAFLD.

Methods

Taiwanese type 2 diabetes patients with inadequate control on insulin secretagogues and metformin, with no history of significant alcohol ingestion, with mildly elevated serum aspartate amino-transferase (AST) and/or alanine aminotransferase (ALT) and a diagnosis of fatty liver determined by ultrasonography were enrolled. Patients were treated for 24 weeks with rosiglitazone, 4-8 mg daily. Primary endpoints were change in AST and ALT levels from baseline and reduction in A1C < 6.5%.

Results

Out of a total of 68 patients, 60 (88.2%) completed the study treatment without serious adverse events. Treatment in two (2.9%) patients was discontinued due to elevated AST or ALT levels to more than three times the upper limit of normal, and noncompliance or loss of follow-up in six (8.8%) patients. Of the 60 patients who completed the study treatment, mean fasting plasma glucose, A1C, fasting plasma insulin, mean ALT and homeostasis model assessment for insulin resistance were all significantly reduced. Normal AST and ALT levels were achieved and maintained for at least three consecutive measurements and through to the end of the study period in 20 (33.3%) patients. Weight increased by a mean of 2.6 ± 2.4 kg (p<0.001).

Conclusion

Rosiglitazone was reasonably well tolerated in patients with inadequately controlled type 2 diabetes and NAFLD. One-third of patients showed improved liver function after treatment.

Effects of PREMIER Lifestyle Modifications on Participants With and Without the Metabolic Syndrome

Lifestyle modification can reduce blood pressure and lower cardiovascular risk. Established recommendations include weight loss, sodium reduction, and increased physical activity. PREMIER studied the effects of lifestyle interventions based on established recommendations alone and with the addition of the Dietary Approaches to Stop Hypertension (DASH) dietary pattern. This analysis aimed to assess the interventions’ impact on cardiometabolic variables in participants with, compared with those without, metabolic syndrome. The primary outcome was 6-month change in systolic blood pressure. Participants with prehypertension or stage-1 hypertension were randomly assigned to an advice only control group, a 6-month intensive behavioral intervention group of established recommendations (EST), or an established recommendations plus DASH group (EST+DASH). Metabolic syndrome was defined per National Cholesterol and Education Program Adult Treatment Panel III. We used general linear models to test intervention effects on change in blood pressure, lipids, and insulin resistance (homeostasis model assessment), in subgroups defined by the presence or absence of metabolic syndrome. Of 796 participants, 399 had metabolic syndrome. Both EST and EST+DASH reduced the primary outcome variable, systolic blood pressure. Within the EST+DASH group, those with and without metabolic syndrome responded similarly ( P =0.231). However, within EST, those with metabolic syndrome had a poorer response, with a decrease in systolic blood pressure of 8.4 mm Hg versus 12.0 mm Hg in those without metabolic syndrome ( P =0.002). Thus, metabolic syndrome attenuated the systolic blood pressure reduction of EST, but this attenuation was overcome in EST+DASH. Finally, diastolic blood pressure, lipids, and homeostasis model assessment responded similarly to both interventions regardless of metabolic syndrome status. Our data suggest that strategies for lowering BP in individuals with metabolic syndrome may be enhanced by recommendations to adopt the DASH dietary pattern.

Hypertension and the Cardiometabolic Syndrome

Hypertension and cardiovascular disease are leading causes of morbidity and mortality. Accumulating data demonstrate a relationship between hypertension and several vascular and metabolic abnormalities that are components of the cardiometabolic syndrome. The components of the cardiometabolic syndrome include insulin resistance/hyperinsulinemia, central obesity, dyslipidemia, hypertension, microalbuminuria, increased inflammation, and oxidative stress. There is growing evidence that tissue activation of the renin-angiotensin-aldosterone system participates in endothelial dysfunction, microalbuminuria, insulin resistance, and subsequent cardiovascular and chronic kidney disease. The notion that hypertension is a metabolic as well as a vascular disease opens a new paradigm for the treatment of this disorder.

[Insulin and angiotensin II signaling pathways cross-talk: implications with the association between diabetes mellitus, arterial hypertension and cardiovascular disease]

Insulin (Ins) and angiotensin II (AII) play pivotal roles in the control of two vital and closely related systems: the metabolic and the circulatory, respectively. A failure in the proper action of each of these hormones results, to a variable degree, in the development of two highly prevalent and commonly overlapping diseases--diabetes mellitus (DM) and hypertension (AH). In recent years, a series of studies has revealed a tight connection between the signal transduction pathways that mediate Ins and AII actions in target tissues. This molecular cross-talk occurs at multiple levels and plays an important role in phenomena that range from the action of anti-hypertensive drugs to cardiac hypertrophy and energy acquisition by the heart. At the extracellular level, the angiotensin-converting enzyme controls AII synthesis but also interferes with Ins signaling through the proper regulation of AII and the accumulation of bradykinin. At an early intracellular level, AII, acting through JAK-2/IRS-1/PI3-kinase, JNK and ERK, may induce the serine phosphorylation and inhibition of key elements of the Ins-signaling pathway. Finally, by inducing the expression of the regulatory protein SOCS-3, AII may impose a late control on the Ins signal. This review will focus on the main advances obtained in this field and will discuss the implications of this molecular cross-talk in the common clinical association between DM and AH.

Ultrasonographic evaluation of liver volume and the metabolic syndrome in obese women

Non-alcoholic fatty liver disease is a common finding in obese subjects, and increasing evidence has been provided suggesting that it represents the hepatic component of the metabolic syndrome. The aim of this study was to evaluate whether the extent of liver enlargement is related to the severity of the metabolic syndrome in obese women. The relationship between ultrasound- measured hepatic left lobe volume (HLLV) and various features of the metabolic syndrome was evaluated in 85 obese women. The mean+/-SD value of HLLV in obese women was 431+/-214 ml (range 46-1019 ml) while it was 187+/-31 ml (range 143-258 ml) in lean subjects. In a multiple logistic regression analysis, ultrasound-measured intra-abdominal fat was the only anthropometric measure independently associated with HLLV. A strong positive association was found between HLLV and serum liver enzymes, triglycerides, glucose, insulin, uric acid, C reactive protein, systolic and diastolic blood pressure, while a negative correlation was observed between HLLV and HDL cholesterol. The values of HLLV corresponding to the cut-off values of various risk factors for the diagnosis of the metabolic syndrome were calculated, yielding a mean value of 465 ml. In conclusion, ultrasound measurement of HLLV represents a simple, reliable and low-cost tool for the evaluation of liver involvement in the metabolic syndrome. The strong association between liver enlargement and various cardiovascular risk factors associated with insulin resistance supports the role of liver steatosis as an important link among the many facets of the metabolic syndrome in human obesity.

Bradykinin augments insulin-stimulated glucose transport in rat adipocytes via endothelial nitric oxide synthase-mediated inhibition of Jun NH2-terminal kinase

An increase in bradykinin has been suggested to contribute to the enhanced insulin sensitivity observed in the presence of ACE inhibitors. To investigate a potential direct, nonvascular effect on an insulin target tissue, the effect of bradykinin on glucose uptake and insulin signaling was studied in primary rat adipocytes. Whereas basal glucose uptake was not altered, bradykinin augmented insulin-stimulated glucose uptake twofold, which was blocked by HOE-140, a bradykinin B2 receptor antagonist. The bradykinin effect on glucose uptake was nitric oxide (NO) dependent, mimicked by NO donors and absent in adipocytes from endothelial NO synthase-/- mice. Investigation of insulin signaling revealed that bradykinin enhanced insulin receptor substrate-1 (IRS-1) Tyr phosphorylation, Akt/protein kinase B phosphorylation, and GLUT4 translocation. In contrast, insulin-stimulated extracellular signal-regulated kinase1/2 and Jun NH2-terminal kinase (JNK) activation were decreased in the presence of bradykinin, accompanied by decreased IRS-1 Ser307 phosphorylation. Furthermore, bradykinin did not enhance insulin action in the presence of the JNK inhibitor, SP-600125, or in adipocytes from JNK1-/- mice. These data indicate that bradykinin enhances insulin sensitivity in adipocytes via an NO-dependent pathway that acts by modulating the feedback inhibition of insulin signaling at the level of IRS-1.

The metabolic syndrome and nonfatal ischemic heart disease; a population-based study

OBJECTIVES

Metabolic syndrome comprises insulin resistance, abdominal fat distribution, dyslipidemia and hypertension. The metabolic syndrome is expected to be diagnosed in millions of subjects in the near future worldwide. There are very few data in literature clearly documenting that subjects with metabolic syndrome have an increased cardiovascular risk.

DESIGN

Cross-sectional, population-based study.

MATERIALS AND METHODS

We used National Cholesterol Education Program (NCEP)-Adult Treatment Panel (ATP)-III criteria and Minnesota Code of a 12-lead resting electrocardiogram (EKG) to assess the association of metabolic syndrome and nonfatal ischemic heart disease in 3723 subjects, aged 25 years and over, selected by cluster random sampling in three Iranian ports in the northern Persian Gulf. Electrocardiogram with evidence of IHD (IHD EKG) was defined as myocardial infarction (codes 1.1 and 1.2) and ischemia (codes 1.3, 4.1-4.4, 5.1-5.3 and 7.1) together.

RESULTS

An estimated 49.08% (52.04% of males and 46.34% of females) were identified as fulfilling NCEP-ATP III criteria for diagnosing the metabolic syndrome. Prevalence of EKG with evidence of ischemic heart disease (IHD EKG) was 12.7% (10.4% for men and 14.7% for women, p<0.0001). In multiple logistic regression analysis, metabolic syndrome was found to have a significant association with IHD EKG [OR=1.35, CI (1.09-1.66), p=0.005] after adjusting for sex and age. Of the metabolic syndrome components, elevated blood sugar (OR=2.69, p<0.001), high blood pressure (OR=1.79, p=0.001) and low HDL-C (OR=1.27, p=0.02) had significant independent association with IHD EKG.

CONCLUSION

The metabolic syndrome, which occurs very frequently in the general population, has a significant association with nonfatal ischemic heart disease by electrocardiogram criteria.

Prevalência de síndrome metabólica em uma área rural do semi-árido baiano

O crescimento de alterações da tolerância à glicose em populações rurais e a carência de dados nacionais sobre ocorrência de Síndrome Metabólica (SM) motivaram o desenvolvimento deste estudo de prevalência de SM no distrito rural de Cavunge, semi-árido baiano. Amostra aleatória de base populacional foi constituída por 240 indivíduos com idade > 25 anos, 102 (42,5%) homens e 138 (57,5%) mulheres, idade média 49,5 ± 14,9, variando de 25 a 87 anos. Para diagnóstico, utilizou-se a I Diretriz Brasileira de Diagnóstico e Tratamento da SM. A prevalência bruta foi de 30,0% e, após ajustamento por idade, 24,8%. Freqüência de SM foi maior em mulheres (38,4%) que em homens (18,6%), mais elevada entre aqueles com idade > 45 anos (41,4%) que naqueles com idade < 45 anos (15,9%). Estratificação por sexo e idade revelou prevalência maior entre mulheres com idade > 45 anos (56,9%), possivelmente associada à menopausa. Presença de SM na ausência de seus componentes melhor estabelecidos, alteração da glicemia e obesidade, sugere a importância do diagnóstico sindrômico, sinalizado pelo elevado valor preditivo encontrado para algumas alterações metabólicas isoladas. A alta prevalência justifica atenção ao tratamento do conjunto da síndrome, retardando ou evitando conseqüências futuras, como diabetes e doença cardiovascular.

The multi-faceted cross-talk between the insulin and angiotensin II signaling systems

Insulin and angiotensin II are hormones that play pivotal roles in the control of two vital and closely related systems, the metabolic and the circulatory systems, respectively. A failure in the proper action of each of these hormones results, to a variable degree, in the development of two highly prevalent and commonly overlapping diseases-diabetes mellitus and hypertension. In recent years, a series of studies has revealed a tight connection between the signal transduction pathways that mediate insulin and angiotensin II actions in target tissues. This molecular cross-talk occurs at multiple levels and plays an important role in phenomena that range from the action of anti-hypertensive drugs to cardiac hypertrophy and energy acquisition by the heart. At the extracellular level, the angiotensin-converting enzyme controls angiotensin II synthesis but also interferes with insulin signaling through the proper regulation of angiotensin II and through the accumulation of bradykinin. At an early intracellular level, angiotensin II, acting through JAK-2/IRS-1/PI3-kinase, JNK and ERK, may induce the serine phosphorylation and inhibition of key elements of the insulin-signaling pathway. Finally, by inducing the expression of the regulatory protein SOCS-3, angiotensin II may impose a late control on the insulin signal. This review will focus on the main advances obtained in this field and will discuss the implications of this molecular cross-talk in the common clinical association between diabetes mellitus and hypertension.

Metabolic syndrome in the elderly

The prevalence of metabolic syndrome is increasing worldwide, especially among the elderly. Due to multiple age-related physiologic mechanisms, the elderly are at increased risk of developing intra-abdominal obesity and the metabolic syndrome, including nonalcoholic steatohepatitis. Metabolic syndrome consists of obesity, insulin resistance, dyslipidemia, and hypertension leading to increased risk of cardiovascular disease (CVD) and renal events. With the future population dynamics, the metabolic syndrome should be emphasized among the health care field, researchers, and clinicians. Without proactive and preventative efforts, elderly patients and the health care system will likely experience an epidemic of the metabolic syndrome and the associated CVD.

The Metabolic Syndrome: Recognition and Management

The National Cholesterol Education Program defines the metabolic syndrome as three or more of five abnormalities: waist circumference of >40 in (102 cm) for men or >35 in (88 cm) for women, triglyceride level of > or =150 mg/dL, high-density lipoprotein cholesterol of <40 mg/dL in men or <50 mg/dL in women, blood pressure of > or =130 or > or =85 mm Hg, and fasting glucose of > or =110 mg/dL. It is related to insulin resistance, but the two terms are not synonymous. Both are associated strongly with obesity. The metabolic syndrome is important as an indicator of increased risk of cardiovascular disease (CVD) in patients with and without clinical CVD. The CVD risk of the metabolic syndrome is greater than that conferred by any single CVD risk factor. Since risk factors tend to cluster, if one component of the metabolic syndrome is present, one should assess for other risk factors. The metabolic syndrome is also predictive of new-onset type 2 diabetes. Early diagnosis provides justification for measures that can improve components of the syndrome and reduce CVD risk. The management strategy for metabolic syndrome focuses on overall CVD risk rather than single risk factors; effective therapy includes priority for weight reduction and increased physical activity. Pharmacotherapy is typically needed for control of high blood pressure, hypercoagulability, and increased levels of blood glucose and triglycerides.

Sympathetic activity and cardiovascular risk factors in young men in the low, normal, and high blood pressure ranges

We hypothesized that resting blood pressure is related to sympathetic activity in young men who are unaware of their blood pressure status in high, normal, and low ranges and that there is a relationship between sympathetic activity and coronary risk factors. Forty-three healthy, young men from the 1st [group 1, 106/52+/-2/2 mm Hg (+/-SEM), n=15], 50th (group 2, 129/79+/-2/1 mm Hg, n=15), and 98th to 99th percentile (group 3, 166/97+/-3/1 mm Hg, n=13) at a blood pressure screening were studied with intraarterial blood pressure, heart rate, and arterial plasma catecholamine responses to a mental, cold pressor, and orthostatic stress test. At baseline, group 3 had significant higher blood pressure (137/74+/-3/2 mm Hg) than group 2 (126/66+/-3/2 mm Hg; P<0.01) and group 1 (116/62+/-2/1 mm Hg; P<0.001). Group 1 had lower systolic blood pressure than group 2 (P=0.007). Baseline epinephrine and norepinephrine showed a clear positive linear trend (P<0.05), with the lowest values being in group 1 and highest in group 3. High-density lipoprotein was negatively related to epinephrine (r=-0.387; P=0.010). Mental stress was the only test that showed significant differences in cardiovascular and sympathetic responses among the groups, where group 3 had a more pronounced response in systolic and diastolic blood pressure and heart rate compared with group 1 (P<0.001) and group 2 (P<0.01). Furthermore, we found significant positive linear trends for Deltacatecholamines during mental stress across the groups (Deltaepinephrine P=0.001 and Deltanorepinephrine P=0.026, ANOVA). We conclude that resting blood pressure reflects both variation in resting arterial catecholamines and variation in cardiovascular and sympathetic responses specifically to mental stress.

Thiazolidinediones

Our knowledge and understanding of the role played by peroxisome proliferator-activated gamma receptors in physiology and pathophysiology has expanded dramatically over the past 5 years. Originally described as having important functions in adipogenesis and glucose homeostasis, their pharmacologic agonists, the thiazolidinediones, were introduced as antihyperglycemic, insulin-sensitizing agents for the management of type 2 diabetes mellitus. However, it was to some degree inevitable that the thiazolidinediones would be rapidly recognized as having vasculoprotective properties beyond glycemic control that might also be beneficial. First, diabetic complications are vascular in nature, the earliest feature of these is endothelial dysfunction. Second, it is being increasingly appreciated that these complications develop through inflammatory and procoagulant pathways in which increased oxidative stress is considered a major etiologic mechanism, and which are closely linked to the presence of insulin resistance, visceral obesity, and hyperglycemia. Early appreciation that the thiazolidinediones have antioxidant, anti-inflammatory, anti-procoagulant, and antiproliferative properties in addition to their insulin-sensitizing, anti-lipotoxic properties created a marriage of investigative pathways that has not only led to a very large body of literature on the pleiotropic effects of thiazolidinediones, but also to the development of new understandings of the connections between insulin resistance, obesity, and hyperglycemia and the onset of vascular disease. Understandably, most of the focus has been directed at the macrovascular complications of diabetes, since these are the major causes of morbidity and mortality in this population. However, there is evidence that these agents may have benefits for the microvascular complications as well, and their potential role for cardiovascular disease prevention in non-diabetic patients with the metabolic syndrome is a logical extension of the work performed in diabetes. The recently reported results of the effects of pioglitazone versus placebo on cardiovascular events in patients with type 2 diabetes support the contention that these agents have vasculoprotective effects.

Peripheral metabolism of thyroid hormone and glucose homeostasis

Thyroid hormone action has long been recognized as an important determinant of glucose homeostasis. Recent advances in the knowledge of the physiology of the deiodinases indicate that through tissue-specific regulation of thyroid hormone metabolism, leading to local specificity of thyroid hormone action and target gene transcription patterns, they may have an important function in the modulation of carbohydrate metabolism. This review briefly addresses the role of thyroid hormone action on glucose homeostasis with a specific focus on the significance of the peripheral metabolism of thyroid hormone in the regulation of glucose homeostasis and insulin sensitivity.

The effect of fenofibrate on the levels of high sensitivity C-reactive protein in dyslipidaemic hypertensive patients

It is now well documented that hypertension is associated with a chronic low-grade inflammatory state. Levels of high-sensitivity C-reactive protein (hs-CRP), a marker of systemic inflammation and a mediator of atherothrombotic disease, have been shown to correlate with cardiovascular disease risk. Our objective was to evaluate the effect of fenofibrate on the levels of hs-CRP in dyslipidaemic hypertensive patients. We selected 30 dyslipidaemic hypertensive patients and 20 normolipidemic normotensive healthy subjects. Dyslipidaemic hypertensive patients were treated with fenofibrate 200 mg/day for 3 months. Serum hs-CRP and metabolic parameters were evaluated at baseline in both groups and after fenofibrate treatment in dyslipidaemic hypertensive patients. At baseline, significantly higher hs-CRP levels were found in dyslipidaemic hypertensive patients than normal subjects (0.48 +/- 0.3 vs. 0.15 +/- 0.1 mg/dl, p < 0.01). Total cholesterol, low-density lipoprotein cholesterol and triglyceride significantly decreased (p < 0.05, p < 0.05 and p < 0.01, respectively), and levels of high-density lipoprotein cholesterol significantly increased (p < 0.05) after treatment with fenofibrate in dyslipidaemic hypertensive group. Levels of hs-CRP significantly decreased after fenofibrate treatment from a mean of 0.48 +/- 0.3 mg/dl to vs. 0.16 +/- 0.2 mg/dl, p < 0.01). Our findings suggest that fenofibrate may be used as a first-line therapy for improving the plasma lipids profile as well as the chronic low-grade inflammatory state in dyslipidaemia and hypertension.