Role of insulin in regulation of lipoprotein metabolism in diabetes

Gender differences in the impact of 3-year status changes of metabolic syndrome and its components on incident type 2 diabetes mellitus: a decade of follow-up in the Tehran Lipid and Glucose Study

Background

The aim of this study was to examine the gender differences in the association between status changes of metabolic syndrome (MetS) and its components, using Joint Interim Statement (JIS) criteria, with the risk of type 2 diabetes mellitus (T2DM) among an urban population.

Methods

The study included 4,463 Iranian adult participants (2,549 women) aged ≥20 years. Based on status changes of MetS and its components during 3 years, subjects were categorized into four groups: MetS-free (reference), MetS-developed, MetS-recovery, and MetS-stable. A similar categorization was applied to MetS components. Multivariable Cox regression models were used for estimating hazard ratios (HRs) and women-to-men ratios of HRs (RHRs).

Results

During a median follow-up of 9.3 years, 625 T2DM events (351 women) occurred. Compared with the reference, the HRs of the MetS-developed, -recovery, and -stable groups among men for incident T2DM were 2.90, 2.60, and 4.92; the corresponding values for women were 2.73, 2.88, and 5.21, respectively (all p-values < 0.01), without significant gender difference in these relationships. In both genders, the fasting plasma glucose (FPG) component, regardless of the change in status, was strongly and significantly associated with incident T2DM with HRs ranging from 2.49 to 9.42; a similar association was also found for high waist circumference (WC)-recovery and -stable groups, with HRs ranging from 1.58 to 2.85 (p-values ≤ 0.05). Regarding gender differences, the development and persistence of high blood pressure (BP) status exposed men to greater T2DM risk than women with women-to-men RHRs of 0.43 (0.26-0.72) and 0.58 (0.39-0.86), respectively. Moreover, stable low levels of high-density lipoprotein cholesterol (HDL-C) and high triglyceride (TG) levels conferred higher T2DM risk in women than in men, with women-to-men RHRs of 1.67 (0.98-2.86) and 1.44 (0.98-2.14), respectively (both p-values = 0.06).

Conclusion

Among Tehranian adults, in both genders, all status changes of MetS, even those recovered from MetS, have a higher risk of T2DM compared to those who never had MetS. Also, all statuses of high FPG, in addition to recovered and stable high WC, were strongly associated with T2DM risk. Specifically, men with stable or developed high BP and women with stable dyslipidemic status were at differentially increased risk of incident T2DM.

Lipoproteins and Cardiovascular Disease: An Update on the Clinical Significance of Atherogenic Small, Dense LDL and New Therapeutical Options

Dyslipidemia is a potent risk factor for the genesis and progression of cardiovascular disease (CVD), and both the concentration and type of low-density lipoproteins (LDL) augment this association. The small, dense LDL (sdLDL) subfraction is the subtype which is most strongly predictive of atherosclerosis and cardiovascular events. In addition to the traditionally available lipid-lowering treatment options, certain novel therapies have been shown to favorably impact sdLDL, among them the antidiabetic class of agents known as glucagon-like peptide 1 receptor agonists (GLP1-RAs). These drugs seem to alter the pathophysiologic mechanisms responsible for the formation and accumulation of atherogenic lipoprotein particles, thus potentially reducing cardiovascular outcomes. They represent a uniquely targeted therapeutic approach to reduce cardiometabolic risk and warrant further study for their beneficial nonglycemic actions.

Updates on the Current Treatments for Diabetic Retinopathy and Possibility of Future Oral Therapy

Diabetic retinopathy (DR) is a complication of diabetes and one of the leading causes of vision loss worldwide. Despite extensive efforts to reduce visual impairment, the prevalence of DR is still increasing. The initial pathophysiology of DR includes damage to vascular endothelial cells and loss of pericytes. Ensuing hypoxic responses trigger the expression of vascular endothelial growth factor (VEGF) and other pro-angiogenic factors. At present, the most effective treatment for DR and diabetic macular edema (DME) is the control of blood glucose levels. More advanced cases require laser, anti-VEGF therapy, steroid, and vitrectomy. Pan-retinal photocoagulation for non-proliferative diabetic retinopathy (NPDR) is well established and has demonstrated promising outcomes for preventing the progressive stage of DR. Furthermore, the efficacy of laser therapies such as grid and subthreshold diode laser micropulse photocoagulation (SDM) for DME has been reported. Vitrectomy has been performed for vitreous hemorrhage and tractional retinal detachment for patients with PDR. In addition, anti-VEGF treatment has been widely used for DME, and recently its potential to prevent the progression of PDR has been remarked. Even with these treatments, many patients with DR lose their vision and suffer from potential side effects. Thus, we need alternative treatments to address these limitations. In recent years, the relationship between DR, lipid metabolism, and inflammation has been featured. Research in diabetic animal models points to peroxisome proliferator-activated receptor alpha (PPARα) activation in cellular metabolism and inflammation by oral fenofibrate and/or pemafibrate as a promising target for DR. In this paper, we review the status of existing therapies, summarize PPARα activation therapies for DR, and discuss their potentials as promising DR treatments.

Type 2 Diabetes Modifies Skeletal Muscle Gene Expression Response to Gastric Bypass Surgery

INTRODUCTION

Roux-en-Y gastric bypass (RYGB) is an effective treatment for type 2 diabetes mellitus (T2DM) that can result in remission of clinical symptoms, yet mechanisms for improved skeletal muscle health are poorly understood. We sought to define the impact of existing T2DM on RYGB-induced muscle transcriptome changes.

METHODS

Vastus lateralis biopsy transcriptomes were generated pre- and 1-year post-RYGB in black adult females with (T2D; n = 5, age = 51 ± 6 years, BMI = 53.0 ± 5.8 kg/m²) and without (CON; n = 7, 43 ± 6 years, 51.0 ± 9.2 kg/m²) T2DM. Insulin, glucose, and HOMA-IR were measured in blood at the same time points. ANCOVA detected differentially expressed genes (p < 0.01, fold change < |1.2|), which were used to identify enriched biological pathways.

RESULTS

Pre-RYGB, 95 probes were downregulated with T2D including subunits of mitochondrial complex I. Post-RYGB, the T2D group had normalized gene expression when compared to their non-diabetic counterparts with only three probes remaining significantly different. In the T2D, we identified 52 probes upregulated from pre- to post-RYGB, including NDFUB7 and NDFUA1.

CONCLUSION

Black females with T2DM show extensive downregulation of genes across aerobic metabolism pathways prior to RYGB, which resolves 1 year post-RYGB and is related to improvements in clinical markers. These data support efficacy of RYGB for improving skeletal muscle health, especially in patients with T2DM.

Qiju Dihuang Decoction for Hypertension: A Systematic Review and Meta-Analysis

OBJECTIVE

To systematically evaluate the efficacy of Chinese herbal medicine Qiju Dihuang Decoction (QDD) for hypertension.

METHODS

A comprehensive literature search of randomized controlled trials using QDD to treat hypertension was conducted in 7 electronic databases, including Chinese databases. Subjects and abstracts of the trials were read in NoteExpress for preliminary screening, and the full text was read for further screening. The data extraction table was made for the selected 19 trials, and risk of bias was assessed by using the Cochrane collaboration tool, followed by data analysis using Rev Man 5.3.

RESULTS

The antihypertensive efficacy of QDD is 1.45 times that of antihypertensive drugs and 1.56 times that of conventional therapies, which can also reduce the endothelin level. QPAD exhibits an antihypertensive effect, and its clinical efficacy is 1.34 times and 1.61 times that of antihypertensive drugs, which can not only significantly lower the diastolic blood pressure but also reduce the 24 h mean ambulate blood pressure. At the same time, it can decrease the TCM syndrome score, inhibit the inflammation, protect the renal function, reduce the insulin resistance, and improve the life quality of patients.

CONCLUSION

QDD can effectively reduce blood pressure and improve the life quality of patients with hypertension, which plays a certain role in preventing hypertension complications. However, due to the methodological deficiencies, more rigorous randomized controlled trials will be needed in the future to provide stronger evidence.

In contrast to Western diet, a plant-based, high-fat, low-sugar diet does not exacerbate retinal endothelial injury in streptozotocin-induced diabetes

Controversy remains about how diet affects the vascular endothelial dysfunction associated with disordered insulin-glucose homeostasis. It is postulated that the type and level of certain macronutrients contribute to endothelial dysfunction in vascular diabetes complications. However, it is not well understood how specific macronutrients affect the molecular inflammatory response under conditions of hyperglycemia. Here, we examined retinal microvascular endothelial injury in streptozotocin (STZ)-diabetic rats fed a laboratory Western diet (WD). WD, characterized by its high content of saturated fat, cholesterol, and sugar, significantly increased retinal leukocyte accumulation and endothelial injury in the STZ-diabetic rats. Suppression of endothelial NF-κB signaling in the STZ model reduced the WD-induced increase in leukocyte accumulation. To isolate the effect of dietary fat, we generated high-fat diets with varying fatty acid balance and type. These diets contained moderate amounts of carbohydrates but no sugar. We found that neither high levels of saturated or unsaturated fats per se increased retinal leukocyte accumulation and endothelial injury in the STZ-diabetic rat model but that the combination of high levels of dietary cholesterol with specific saturated fatty acids that are abundant in WD exacerbated leukocyte accumulation and endothelial injury in the retinas of STZ-diabetic rats.-Barakat, A., Nakao, S., Zandi, S., Sun, D., Schmidt-Ullrich, R., Hayes, K. C., Hafezi-Moghadam, A. In contrast to Western diet, a plant-based, high-fat, low-sugar diet does not exacerbate retinal endothelial injury in streptozotocin-induced diabetes.

ADRB3 Gene Trp64Arg Polymorphism and Essential Hypertension: A Meta-Analysis Including 9,555 Subjects

Background: Presence of the β3-Adrenergic receptor (ADRB3) gene Trp64Arg (T64A) polymorphism may be associated with an increased susceptibility for essential hypertension (EH). A clear consensus, however, has yet to be reached.

Objective and methods: To further elucidate the relationship between the ADRB3 gene Trp64Arg polymorphism and EH, a meta-analysis of 9,555 subjects aggregated from 16 individual studies was performed. The combined odds ratios (ORs) and their corresponding 95% confidence intervals (CI) were evaluated using either a random or fixed effect model.

Results: We found a marginally significant association between ADRB3 gene Trp64Arg polymorphism and EH in the whole population under the additive genetic model (OR: 1.200, 95% CI: 1.00–1.43, P = 0.049). Association within the Chinese subgroup, however, was significant under allelic (OR: 1.150, 95% CI: 1.002–1.320, P = 0.046), dominant (OR: 1.213, 95% CI: 1.005–1.464, P = 0.044), heterozygous (OR: 1.430, 95% CI:1.040–1.970, P = 0.03), and additive genetic models (OR: 1.280, 95% CI: 1.030–1.580, P = 0.02). A significant association was also found in the Caucasian subgroup under allelic (OR: 1.850, 95% CI: 1. 260–2.720, P = 0.002), dominant (OR: 2.004, 95% CI: 1.316–3.052, P = 0.001), heterozygous (OR: 2.220, 95% CI: 1.450–3.400, P = 0.0002), and additive genetic models (OR: 2.000, 95% CI: 1. 330–3.010, P = 0.0009).

Conclusions: The presence of the ADRB3 gene Trp64Arg polymorphism is positively associated with EH, especially in the Chinese and Caucasian population. The Arg allele carriers of ADRB3 gene Trp64Arg polymorphism may be at an increased risk for developing EH.

The role of dyslipidemia in diabetic retinopathy

Diabetic retinopathy (DR) affects over 93million people worldwide and is the number one cause of blindness among working age adults. These indicators coupled with the projected rise of patients diagnosed with diabetes, makes DR a serious and prevalent vision threating disease. Data from recent clinical trials demonstrate that in addition to the well accepted role of hyperglycemia, dyslipidemia is an important, but often overlooked factor in the development of DR. The central aim of this review article is to showcase the critical role of dyslipidemia in DR progression as well as highlight novel therapeutic solutions that take advantage of the vital roles lipid metabolism plays in DR progression.

Development of a tree shrew metabolic syndrome model and use of umbilical cord mesenchymal stem cell transplantation for treatment

The aim of this study was to establish a tree shrew metabolic syndrome model and demonstrate the utility of MSCs in treating metabolic syndrome. We used tree shrew umbilical cord mesenchymal stem cell (TS-UC-MSC) transplantation for the treatment of metabolic syndrome to demonstrate the clinical application of these stem cells and to provide a theoretical basis and reference methods for this treatment. Tree shrew metabolic syndrome model showed significant insulin resistance, high blood sugar, lipid metabolism disorders, and hypertension, consistent with the diagnostic criteria. TS-UC-MSC transplantation at 16 weeks significantly reduced blood sugar and lipid levels, improved insulin resistance and the regulation of insulin secretion, and reduced the expression levels of the pro-inflammatory cytokines IL-1 and IL-6 (P < 0.05). The transplanted TS-UC-MSCs targeted the liver, kidney and pancreas; reduced liver cell degeneration, necrosis, and inflammatory exudation; mitigated bleeding congestion and inflammatory cell infiltration in the kidney; and reduced islet cell degeneration and necrosis. We successfully developed a tree shrew metabolic syndrome model and showed that MSC migrate in diseased organs and can attenuate metabolic syndrome severity in a tree shrew model.

Developmental origins of metabolic disorders: The need for biomarker candidates and therapeutic targets from adequate preclinical models

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The research on obesity and associated disorders should rely on contrasted biomarkers.

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The discovery of biomarkers is flawed by inherent variability of human data.

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Hence, preclinical studies in animal models are essential.

The investigation on obesity and associated disorders have changed from an scenario in which genome drove the phenotype to a dynamic setup in which prenatal and early-postnatal conditions are determinant. However, research in human beings is difficult due to confounding factors (lifestyle and socioeconomic heterogeneity) plus ethical issues. Hence, there is currently an intensive effort for developing adequate preclinical models, aiming for an adequate combination of basic studies in rodent models and specific preclinical studies in large animals. The results of these research strategies may increase the identification and development of contrasted biomarkers and therapeutic targets.

Effects of low glycaemic index/low glycaemic load vs. high glycaemic index/ high glycaemic load diets on overweight/obesity and associated risk factors in children and adolescents: a systematic review and meta-analysis

The objective of the present systematic review and meta-analysis was to synthesize the available literature data investigating the effects of low glycaemic index/low glycamic load dietary regimens on anthropometric parameters, blood lipid profiles, and indicators of glucose metabolism in children and adolescents. Literature search was performed using the electronic databases MEDLINE, EMBASE, and the Cochrane Central Register of trials with restrictions to randomized controlled trials, but no limitations concerning language and publication date. Parameters taken into account were: body weight, body mass index, z-score of body mass index, fat mass, fat-free mass, height, waist cicrumference, hip circumference, waist-to-hip ratio, total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, diastolic and systolic blood pressure, fasting serum glucose, fasting serum insulin, HOMA-index, glycosylated haemoglobin, and C-reactive protein. Meta-analyses were performed for each parameter to assess pooled effect in terms of weighted mean differences between the post-intervention (or differences in means) of the low glycaemic index diets and the respective high glycaemic index counterparts. Data analysis was performed using the Review Manager 5.3. software. Nine studies enrolling 1.065 children or adolescents met the inclusion criteria. Compared to diets providing a high gylcaemic index, low glycaemic index protocols resulted in significantly more pronounced decreases in serum triglycerides [mean differences −15.14 mg/dl, 95 %-CI (−26.26, −4.00)] and HOMA-index [mean difference −0.70, 95 %-CI (−1.37, −0.04), fixed-effects model only]. Other parameters under investigation were not affected by either low or high glycaemic indices. The present systematic review and meta-analysis provides evidence of a beneficial effect of a low glycaemic index/load diet in children and adolescents being either overweight or obese. Regarding the limitations of this analysis, further studies adopting a homogenous design are necessary to assure the present findings. Since low glycaemic index/load regimens were not associated with a deterioration of the outcome parameters, these diets should not be categorically excluded when looking for alternatives to change lifestyle habits in this age group.

A routine biomarker-based risk prediction model for metabolic syndrome in urban Han Chinese population

Background

Many MetS related biomarkers had been discovered, which provided the possibility for building the MetS prediction model. In this paper we aimed to develop a novel routine biomarker-based risk prediction model for MetS in urban Han Chinese population.

Methods

Exploring Factor analysis (EFA) was firstly conducted in MetS positive 13,345 males and 3,212 females respectively for extracting synthetic latent predictors (SLPs) from 11 routine biomarkers. Then, depending on the cohort with 5 years follow-up in 1,565 subjects (male 1,020 and female 545), a Cox model for predicting 5 years MetS was built by using SLPs as predictor; Area under the ROC curves (AUC) with 10 fold cross validation was used to evaluate its power. Absolute risk (AR) and relative absolute risk (RAR) were calculated to develop a risk matrix for visualization of risk assessment.

Results

Six SLPs were extracted by EFA from 11 routine health check-up biomarkers. Each of them reflected the specific pathogenesis of MetS, with inflammatory factor (IF) contributed by WBC & LC & NGC, erythrocyte parameter factor (EPF) by Hb & HCT, blood pressure factor (BPF) by SBP & DBP, lipid metabolism factor (LMF) by TG & HDL-C, obesity condition factor (OCF) by BMI, and glucose metabolism factor (GMF) by FBG with the total contribution of 81.55% and 79.65% for males and females respectively. The proposed metabolic syndrome synthetic predictor (MSP) based predict model demonstrated good performance for predicting 5 years MetS with the AUC of 0.802 (95% CI 0.776-0.826) in males and 0.902 (95% CI 0.874-0.925) in females respectively, even after 10 fold cross validation, AUC was still enough high with 0.796 (95% CI 0.770-0.821) in males and 0.897 (95% CI 0.868-0.921) in females. More importantly, the MSP based risk matrix with a series of risk warning index provided a feasible and practical tool for visualization of risk assessment in the prediction of MetS.

Conclusions

MetS could be explained by six SLPs in Chinese urban Han population. The proposed MSP based predict model demonstrated good performance for predicting 5 years MetS, and the MetS-based matrix provided a feasible and practical tool.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-015-1424-z) contains supplementary material, which is available to authorized users.

Testosterone supplementation therapy in the treatment of patients with metabolic syndrome

Metabolic syndrome (MetS) comprises a clinical complex of patient risk factors, including increased waist circumference, high triglyceride levels, low high-density lipoprotein cholesterol level, high blood pressure, and insulin resistance, the presence of which increases the likelihood of developing diabetes and cardiovascular disease. With a quarter of the American adult population affected, MetS and type 2 diabetes mellitus have been referred to as the most significant public health threats of the 21st century. Lifestyle modification and weight loss are recommended, however, no specific pharmacologic treatment is known. Given that low levels of testosterone have been implicated in the pathogenesis of MetS and an inverse relationship exists between circulating testosterone levels and the development of MetS, it is tempting to speculate that men with MetS may benefit from testosterone supplementation therapy. As such, our review examines the role of testosterone and the use of testosterone supplementation therapy as a treatment in men with MetS.

Effect of ω-3 fatty acid ethyl esters on apolipoprotein B-48 kinetics in obese subjects on a weight-loss diet: a new tracer kinetic study in the postprandial state

CONTEXT

Dysregulated chylomicron metabolism may account for hypertriglyceridemia and increased risk of cardiovascular disease in obese subjects. Supplementation with ω-3 fatty acid ethyl ester (FAEE) decreases plasma triglyceride. However, its effect on postprandial chylomicron metabolism in obese subjects on a weight-loss diet has not yet been investigated.

OBJECTIVE

We aimed to examine the effect of ω-3 FAEE supplementation on apolipoprotein (apo) B-48 kinetics in obese subjects on a weight-loss diet.

DESIGN, SETTING, AND PATIENTS

We carried out a 12-week, randomized trial of a hypocaloric diet plus 4 g/d ω-3 FAEE supplementation (46% eicosapentaenoic acid and 38% docosahexaenoic acid) (n = 13) compared with a hypocaloric diet alone (n = 12) on postprandial apoB-48 kinetics in obese subjects after ingestion of an oral load. The apoB-48 kinetics were determined using stable isotope tracer kinetics and multicompartmental modeling.

OUTCOMES MEASURES

We evaluated plasma total and incremental apoB-48 0- to 10-hour area under the curves (AUCs) as well as apoB-48 secretion and fractional catabolic rate.

RESULTS

Weight loss with or without ω-3 FAEE supplementation significantly reduced body weight, total fat mass, homeostasis model assessment score, fasting triglyceride concentration, postprandial triglyceride AUC, and increased plasma high-density lipoprotein cholesterol concentration (P < .05 in all). Compared with weight loss alone, weight loss plus ω-3 FAEE significantly (all P < .05) decreased fasting triglyceride (-11%), apoB-48 (-36%) concentrations, postprandial triglyceride (-21%), and apoB-48 (-22%) total AUCs, as well as incremental postprandial triglyceride AUCs (-32%). The ω-3 FAEE also significantly decreased apoB-48 secretion in the basal state, without a significant effect during the postprandial period (3-6 hours). The fractional catabolic rate of apoB-48 increased with both interventions with no significant independent effect of ω-3 FAEE supplementation.

CONCLUSION

Addition of ω-3 FAEE supplementation to a moderate weight-loss diet in obese subjects can significantly improve chylomicron metabolism by independently decreasing the secretion of apoB-48.

Cardiometabolic risk in overweight subjects with or without relative fat-free mass deficiency: the Strong Heart Study

BACKGROUND AND AIM

Sarcopenia is a condition mainly due to loss of fat-free mass (FFM) in elderly individuals. RFFMD, however, is also frequent in obese subjects due to abnormal body composition. Objective of this study was to evaluate the impact of relative fat-free mass deficiency (RFFMD) on cardiometabolic (CM) risk in obese normoglycemic individuals.

METHODS AND RESULTS

Overweight/obese American Indians from the Strong Heart Study population, without diabetes and with FBG ≤ 110 mg/dL and with GFR >60 mg/mL/1.73 m(2) were selected for this analysis (n = 742). RFFMD was defined on the basis of a multivariable equation previously reported. Fasting glucose and 2 h-OGTT were measured together with urine albumin/creatinine excretion, laboratory and anthropometric parameters. In addition to lower FFM and greater adipose mass, participants with RFFMD had higher body mass index, waist circumference, C-reactive protein, fibrinogen, insulin resistance and urinary albumin/creatinine than participants with normal FFM (all p < 0.001); they also had a greater prevalence of hypertension, impaired glucose tolerance (IGT) or OGTT-diabetes than participants with normal FFM (all p < 0.003) and a near 2-fold greater probability of significant proteinuria (p < 0.01). RFFMD was more frequent in women than in men: significant sex-RFFMD interactions were found for BMI and waist circumference (both p < 0.0001).

CONCLUSIONS

RFFMD in overweight/obese normoglycemic individuals is associated with greater probability of hypertension, abnormalities of glucose tolerance and proteinuria. Assessment of RFFRMD might, therefore, help stratifying cardiometabolic risk among normoglycemic individuals with overweight/obesity.

Effects of Aging on Kidney Graft Function, Oxidative Stress and Gene Expression after Kidney Transplantation

Conflicting results have been reported regarding the effects of donor age, recipient age and donor-recipient age difference on short- and long-term outcomes after kidney transplantation. The aim of this study was to evaluate the effects of recipient age on graft function, oxidative stress, and gene expression after renal transplantation. Fifty male Fischer 344 rats [25 young (Y, 4 months), 25 senior (S, 16 months)] were randomized to 6 groups: 2 sham groups (Y and S, n = 5 in each group) and 4 renal transplant groups[young-to-young (Y-Y), young-to-senior (Y-S), senior-to-young (S-Y), senior-to-senior (S-S), (n = 10 in each group)]. The left kidneys were transplanted from donor to recipient. After 12 weeks, systematic blood pressure, graft weight, graft function, histology and oxidative stress were measured. Microarray analysis and quantitative real-time PCR confirmation were performed to study gene expression in the grafts. There were no differences in renal graft function between young and senior kidney cross-transplantation. Transplanted kidneys showed no significant differences in glomerulosclerosis index compared to non-transplanted kidneys but had significantly different tubulointerstitium scores compared to age-matched controls. Senior rats had lower SOD activity and higher MDA content than young rats. SOD activity was significantly lower and MDA content significantly higher in the Y-S group than in the Y-Y group. There were 548 transcript differences between senior and young kidneys with 36 upregulated and 512 downregulated transcripts. There were 492 transcript differences between Y-S and Y-Y groups with 127 upregulated and 365 downregulated transcripts. There were 1244 transcript differences between the S-Y and S-S groups with 680 upregulated and 574 downregulated transcripts. Oxidative stress and gene expression profile was significantly different in the Y-S compared to the S-Y group. The identified differences were mainly in the MAPK and insulin signal pathways, making these potential targets for therapeutic intervention.

Components of metabolic syndrome and 5-year change in insulin clearance - the Insulin Resistance Atherosclerosis Study

AIMS

Cross-sectional evidence indicates that abdominal adiposity, hypertension, dyslipidaemia and glycaemia are associated with reduced metabolic clearance rate of insulin (MCRI). Little is known about the progression of MCRI and whether components of metabolic syndrome are associated with the change in MCRI. In this study, we examined the association between components of metabolic syndrome and the 5-year change of MCRI.

METHODS

At baseline and 5-year follow-up, we measured fasting plasma triglycerides (TG), high-density lipoprotein (HDL) cholesterol, blood pressure (BP), waist circumference (WC) and fasting blood glucose (FBG) in 784 non-diabetic participants in the Insulin Resistance Atherosclerosis Study. MCRI, insulin sensitivity (SI ) and acute insulin response (AIR) were determined from frequently sampled intravenous glucose tolerance tests.

RESULTS

We observed a 29% decline of MCRI at follow-up. TG, systolic BP and WC at baseline were inversely associated with a decline of MCRI regression models adjusted for age, sex, ethnicity, smoking, alcohol consumption, energy expenditure, family history of diabetes, BMI, SI and AIR [β = -0.057 (95% confidence interval, CI: -0.11, -0.0084) for TG, β = -0.0019 (95% CI: -0.0035, -0.00023) for systolic BP and β = -0.0084 (95% CI: -0.013, -0.0039) for WC; all p < 0.05]. Higher HDL cholesterol at baseline was associated with an increase in MCRI [multivariable-adjusted β = 0.0029 (95% CI: 0.0010, 0.0048), p = 0.002]. FBG at baseline was not associated with MCRI at follow-up [multivariable-adjusted β = 0.0014 (95% CI: -0.0026, 0.0029)].

CONCLUSIONS

MCRI declined progressively over 5 years in a non-diabetic cohort. Components of metabolic syndrome at baseline were associated with a significant change in MCRI.

Mice long-term high-fat diet feeding recapitulates human cardiovascular alterations: an animal model to study the early phases of diabetic cardiomyopathy

Background/Aim

Hypercaloric diet ingestion and sedentary lifestyle result in obesity. Metabolic syndrome is a cluster of clinical features secondary to obesity, considered as a pre-diabetic condition and recognized as an independent risk factor for cardiovascular diseases. To better understand the relationship between obesity, metabolic syndrome and cardiovascular disease as well as for the development of novel therapeutic strategies, animal models that reproduce the etiology, course and outcomes of these pathologies are required. The aim of this work was to characterize the long-term effects of high-fat diet-induced obesity on the mice cardiovascular system, in order to make available a new animal model for diabetic cardiomyopathy.

Methods/Results

Male C57BL/6 mice were fed with a standardized high-fat diet (obese) or regular diet (normal) for 16 months. Metabolic syndrome was evaluated testing plasma glucose, triglycerides, cholesterol, insulin, and glucose tolerance. Arterial pressure was measured using a sphygmomanometer (non invasive method) and by hemodynamic parameters (invasive method). Cardiac anatomy was described based on echocardiography and histological studies. Cardiac function was assessed by cardiac catheterization under a stress test. Cardiac remodelling and metabolic biomarkers were assessed by RT-qPCR and immunoblotting. As of month eight, the obese mice were overweight, hyperglycaemic, insulin resistant, hyperinsulinemic and hypercholesterolemic. At month 16, they also presented normal arterial pressure but altered vascular reactivity (vasoconstriction), and cardiac contractility reserve reduction, heart mass increase, cardiomyocyte hypertrophy, cardiac fibrosis, and heart metabolic compensations. By contrast, the normal mice remained healthy throughout the study.

Conclusions

Mice fed with a high-fat diet for prolonged time recapitulates the etiology, course and outcomes of the early phases of human diabetic cardiomyopathy.

Modulation of cholesterol transport by insulin-treated gestational diabetes mellitus in human full-term placenta

Gestational diabetes mellitus (GDM) is a common complication of pregnancy that is characterized by glucose intolerance, leads to dyslipidemia, and is aggravated by obesity. Cholesterol is taken up by the placenta as part of lipoproteins through the scavenger receptor class B type I receptor (SRBI), low-density lipoprotein receptor (LDLR), and very low density lipoprotein receptor (VLDLR), and its efflux is then mediated by ABCA1 and ABCG1. PCSK9 is involved in the degradation of LDLR and VLDLR. The goal of this study was to evaluate the impact of GDM and prepregnancy body mass index (BMI) on cholesterol transport through the modulation of the expression of several key players. Human full-term placenta, maternal, and venous cord blood samples were obtained at delivery from normal-weight women without GDM (n = 10), normal-weight women with GDM (n = 6), and overweight/obese women with GDM (n = 6). Lipids (total cholesterol, high-density lipoprotein, low-density lipoprotein, triglycerides, free fatty acids, apolipoprotein A1, apolipoprotein B100) levels were evaluated in blood samples. Messenger RNA and protein expression levels (LDLR, VLDLR, SRBI, ABCA1, ABCG1, proprotein convertase subtilisin/kexin type 9, liver x receptors, peroxisome proliferator-activated receptors) were assessed in human full-term placenta, respectively, by real-time RT-PCR and Western blots. Lipoprotein lipase activity was evaluated using a commercial kit on tissue homogenates. Overall, our study demonstrates that GDM affects the maternal and neonatal lipid profiles as well as different key players of placental cholesterol transfer from the maternal to the fetal circulation, depending on the maternal BMI. These changes could affect the fetal metabolism and predispose the fetus to future metabolic diseases.

Relationship between inflammation and metabolic syndrome following treatment with paliperidone for schizophrenia

OBJECTIVE

Metabolic syndrome and antipsychotic medications are associated with inflammation. This study investigated the relationship between inflammation and metabolic syndrome in patients with schizophrenia. It also examined the effects of paliperidone extended release (ER) treatment on metabolic parameters.

METHODS

Data were analyzed from schizophrenic patients who participated in a multi-center, open-label, non-comparative clinical trial. Anthropomorphic measurements (i.e., weight, waist circumference, and blood pressure) were assessed along with fasting laboratory values, including white blood cell (WBC) count, glucose, high-density lipoprotein, and triglycerides.

RESULTS

Among the 225 patients at baseline, the group with the highest WBC count displayed a 5.9-fold risk for metabolic syndrome compared with that of the lowest group. An increase of 10(3)WBCs/μL was associated with a 1.4-fold increased risk for metabolic syndrome. After 24weeks of treatment with paliperidone ER, significant increases were observed in waist circumference and body weight. Changes in WBC count were positively correlated with changes in waist circumference.

CONCLUSIONS

Schizophrenic patients with high levels of inflammation should be carefully monitored for metabolic syndrome. Moreover, strategies to reduce inflammation and obesity may prevent metabolic syndrome in patients with schizophrenia who take atypical antipsychotic medication.

Meta-analysis on theG-308ATumor Necrosis Factor α Gene Variant and Phenotypes Associated with the Metabolic Syndrome

OBJECTIVE

The G-308A tumor necrosis factor (TNF) alpha gene variant has been associated with obesity, insulin resistance, and hypertension. We performed a systematical review of the literature by means of a meta-analysis to assess the association of the G-308A TNFalpha polymorphism with the components of the metabolic syndrome.

RESEARCH METHODS AND PROCEDURES

Studies were identified by searches of the literature for reports using the terms: diabetes, insulin resistance, hypertension, obesity or metabolic syndrome and TNF, variants or polymorphism or alleles, and Nco or -308. From 824 reports, we included 31 observational studies, case control and cohort at baseline, which analyzed the association between the TNFalpha polymorphism and one or more components of the metabolic syndrome. A fixed effect model was used to pool data from individual studies.

RESULTS

Obesity [odds ratio, 1.23; 95% confidence interval (CI), 1.045 to 1.45; p = 0.013] in a total of 3562 individuals from eight homogeneous studies, systolic arterial blood pressure (standardized difference, 0.132; 95% CI, 0.016 to 0.25; p < 0.03) in a total of 1624 individuals from four homogeneous studies and plasma insulin levels (standardized difference, 0.095; 95% CI, 0.020 to 0.17; p = 0.013) in a total of 3720 subjects from 16 homogeneous studies were positively associated with the -308A variant.

DISCUSSION

These results indicate that individuals who carried the -308A TNFalpha gene variant are at 23% risk of developing obesity compared with controls and showed significantly higher systolic arterial blood pressure and plasma insulin levels, supporting the hypothesis that the TNFalpha gene is involved in the pathogenesis of the metabolic syndrome.

Gene polymorphisms and cytokine plasma levels as predictive factors of complications after cardiopulmonary bypass

OBJECTIVE

Cardiopulmonary bypass remains associated with significant morbidity and mortality, in part caused by a systemic inflammatory response that is unpredictable and variable among patients. Several limited studies have suggested associations of cytokine plasma levels or gene polymorphisms with outcome after cardiopulmonary bypass. The present study was to determine the relationships between several circulating cytokines and their polymorphisms (single nucleotide polymorphisms), and the occurrence of postoperative clinical events in patients who underwent coronary artery bypass grafting under cardiopulmonary bypass.

METHODS

Patients were genotyped for single nucleotide polymorphisms of LTA (Cys13Arg, +252A>G), TNF (-308G>A), IL6 (-597G>A, -572G>C, -174G>C), IL10 (-592C>A, c.∗117C>T), and APOE (Cys112Arg, Arg158Cys). Serum samples were collected preoperatively, immediately after cardiopulmonary bypass, and at different postoperative time points to measure cytokine serum levels by enzyme-linked immunosorbent assay. The clinical end point was the composite of postoperative death, low cardiac output syndrome, myocardial infarction, sepsis, and acute renal insufficiency.

RESULTS

Single nucleotide polymorphisms IL6-572GC+CC/IL10-592CC were associated with the clinical end point (P=.032 and P=.009, respectively). In addition to preoperative clinical conditions, the other factor associated with the clinical end point was interleukin-10 plasma levels 24 hours after surgery (P=.017). On the basis of these results, a predictive model of postoperative complications after coronary artery bypass grafting was created.

CONCLUSIONS

Our data suggest that focused genetic testing of the IL6-572G>C and IL10-592C>A single nucleotide polymorphisms might be a tool for identifying patients at the highest risk of poor tolerance to the inflammatory response to cardiopulmonary bypass and for implementing strategies to mitigate it, provided the generalization of these tests makes them reasonably affordable and thus favorably shifts their cost-to-benefit ratio.

Relationship between Metabolic Syndrome and MTHFR Polymorphism in Colorectal Cancer

PURPOSE

There have been studies on the relations between metabolic syndrome and colorectal cancer or on the relations between methylenetetrahydrofolate reductase (MTHFR) polymorphism and colorectal cancer, but reports on the relationship between metabolic syndrome, MTHFR polymorphism and colorectal cancer all together are rare. The aim of this study is to find the interrelation between metabolic syndrome and MTHFR polymorphism in colorectal cancer.

METHODS

This study investigated 255 colorectal cancer patients (cancer group) who underwent surgery in our hospital from March 2003 to December 2008 and compared those patients to 488 healthy patients (control group). The diagnostic criterion for metabolic syndrome was based on the National Cholesterol Education Program-Adult Treatment Panel III (NCEP ATP III), and the MTHFR 677 polymorphism was analyzed.

RESULTS

When colorectal cancer patients and patients in the control group were classified as MTHFR 677 subtypes, there was no difference between the two groups: CC 87 (34.1%), CT 134 (52.6%), and TT 34 (13.3%) for the cancer group and CC 145 (32.4%), CT 238 (53.1%), and TT 65 (14.5%) for the control group. Distributions of MTHFR 677C/T genotype and allele frequencies in the individuals with and without metabolic syndrome in the cancer group showed no differences. Moreover, we could find no differences in distributions of MTHFR 677C/T genotypes in the clinical and the biomedical variables of individuals with and without metabolic syndrome in the cancer group.

CONCLUSION

Our results show no relation between metabolic syndrome and MTHFR polymorphism in colorectal cancer. However, a further prospective study, based on a precise diagnostic criterion for metabolic syndrome, is needed.

Baseline forced expiratory volume in the first second as an independent predictor of development of the metabolic syndrome

A growing body of evidence strongly supports associations between reduced lung function and insulin resistance, type 2 diabetes mellitus, and cardiovascular disease. The present study was undertaken to explore the possibility that reduced lung function is an independent predictor of development of the metabolic syndrome (MetS) and to investigate potential links between reduced lung function and the MetS. A prospective cohort study of reduced lung function as a predictor of subsequent MetS was conducted using 2-year follow-up data for 450 middle-aged adults lacking the MetS at baseline. Data were obtained from the Taipei MJ Health Screening Centers in Taiwan. The MetS was defined according to the modified Adult Treatment Panel III criteria. Over 2 years of follow-up, 26 of the 450 subjects (5.78%) without the MetS at baseline subsequently developed the syndrome. In multiple logistic regression analysis with adjustments for age, sex, body mass index, cigarette smoking, alcohol consumption, and physical activities, reduced forced expiratory volume in the first second (FEV(1)) at baseline remained a predictor of subsequent MetS (relative risk of 4.644, P = .036 for the third [<2.31 L] vs first [>2.88 L] tertile). In Pearson and partial correlation analyses, white blood cell counts and C-reactive protein concentrations were both found to be significantly and negatively correlated with FEV(1). Lower FEV(1) is concluded to serve as an independent predictor of the MetS. Low-grade systemic inflammation is the possible link between reduced lung function and the MetS.

[Pollen Typhae total flavones inhibit expression of interleukin-6 in C2C12 skeletal muscle cells cultured with palmitate]

OBJECTIVE

To observe the effects of Pollen Typhae total flavones (PTF) on expression of interleukin-6 (IL-6) mRNA and protein secretion in C2C12 cell strain of skeletal muscle cells cultured with palmitate, and to explore the mechanism of PTF in relieving insulin resistance (IR).

METHODS

The IR of C2C12 cells was induced by co-culturing with palmitate. The C2C12 cells were divided into normal control group, untreated group, PDTC (a nuclear factor-kappaB inhibitor) treated group, rosiglitazone (ROS)-treated group, ROS+ PDTC-treated group, PTF-treated group and PTF+PDTC-treated group. Sixteen hours after culture, the transportation rate of glucose was observed by (3)H-deoxyglucose uptake method; IL-6 mRNA expression in C2C12 cells was assayed by real time polymerase chain reaction (Real-time PCR), and level of IL-6 protein secretion in culture supernatant was detected by enzyme linked immunosorbent assay.

RESULTS

Compared with the normal control group, the transportation rate of glucose of cells in untreated group was decreased 30.43% after 16-hour palmitate culture, and was increased 32.39% in the PTF-treated group. Compared with the untreated group, the levels of IL-6 mRNA expression in cells and IL-6 protein secretion in supernatant were significantly decreased in the PTF-treated group (P<0.05). The levels of IL-6 mRNA expression in cells and IL-6 protein secretion in supernatant were increased in PTF+PDTC-treated group as compared with PFT-treated group (P<0.05).

CONCLUSION

PTF can inhibit the IL-6 mRNA expression and IL-6 protein secretion via nuclear factor-kappaB pathway in C2C12 skeletal muscle cells, which may be one of its mechanisms in relieving inflammation conditions and insulin resistance in C2C12 skeletal muscle cells.

Sarcopenia: characteristics, mechanisms and functional significance

Sarcopenia reflects a progressive withdrawal of anabolism and an increased catabolism, along with a reduced muscle regeneration capacity. Muscle force and power decline more than muscle dimensions: older muscle is intrinsically weak. Sarcopenic obesity (SO) among the elderly corroborates to the loss of muscle mass increasing the risk of metabolic syndrome development. Recent studies on the musculoskeletal adaptations with ageing and key papers on the mechanisms of muscle wasting, its functional repercussions and on SO are included. Neuropathic, hormonal, immunological, nutritional and physical activity factors contribute to sarcopenia. Selective fast fibre atrophy, loss of motor units and an increase in hybrid fibres are typical findings of ageing. Satellite cell number decreases reducing muscle regeneration capacity. SO promotes further muscle wasting and increases risk of metabolic syndrome development. The proportion of fast to slow fibres seems maintained in old age. In elderly humans, nuclear domain is maintained constant. Basal protein synthesis and breakdown show little changes in old age. Instead, blunting of the anabolic response to feeding and exercise and of the antiproteolytic effect of insulin is observed. Further understanding of the mechanisms of sarcopenia requires disentangling of the effects of ageing alone from those of disuse and disease. The causes of the greater anabolic resistance to feeding and exercise of elderly women need elucidating. The enhancement of muscle regeneration via satellite cell activation via the MAPK/notch molecular pathways seems particularly promising.

Impact of metabolic syndrome, diabetes and prediabetes on cardiovascular events: Tehran lipid and glucose study

AIMS

To compare the cardiovascular disease (CVD) risk associated with the metabolic syndrome (MetS) and dysglycemia, independent of each other during a median follow-up of 6.7 years.

METHODS

Study population included 4018 Iranian subjects >or=40 years, free of CVD or coronary heart disease (CHD) at baseline. Incidence rates and hazard ratio (HR) were estimated by the presence or absence of MetS and dysglycemia. Considering the glycemic status, the ability of MetS in prediction of CVD after adjustment for age, sex and CVD risk factors was assessed.

RESULTS

The prevalence of MetS, impaired fasting glucose or impaired glucose tolerance (IFG/IGT) and diabetes were 51.4%, 27.3%, and 18.7%, respectively. The addition of MetS to diabetes did not change the CVD risk compared to diabetic subjects without MetS (reference group) after adjustment for age and sex [HR: 1.62 (95% CI 0.93-2.81)] and CVD risk factors [HR: 1.49 (95% CI 0.86-2.60)]. However, addition of MetS to IFG/IGT increased the risk of CVD by 2.5 times compared to those with IFG/IGT without MetS (the risk factor adjusted HR: 2.45 (95% CI 1.32-4.55)).

CONCLUSIONS

In Iranian population, MetS did not add to diabetes to predict incident CVD however, IFG/IGT was a significant predictor only in the presence of MetS.

Abnormal expressions of circadian-clock and circadian clock-controlled genes in the livers and kidneys of long-term, high-fat-diet-treated mice

OBJECTIVES

Physiological and behavioral circadian rhythmicities are exhibited by all mammals and are generated by intracellular levels of circadian oscillators, which are composed of transcriptional/translational feedback loops involving a set of circadian-clock genes, such as Clock, Per1-3, Cry1-2, Bmal1, Dbp, E4BP4 and CK1varepsilon. These circadian-clock genes play important roles in regulating circadian rhythms and also energy homeostasis and metabolism. Determining whether obesity induced by high-fat diet affected the expressions of circadian-clock genes and their related genes in peripheral tissues, was the main focus of this study. To address this issue, we fed male C57BL/6 mice a high-fat diet for 11 months to induce obesity, hyperglycemic, hypercholesterolemic and hyperinsulinemic symptoms, and used quantitative real-time reverse transcription-PCR to measure gene expression levels.

RESULTS

We found that the expressions of circadian-clock genes and circadian clock-controlled genes, including Per1-3, Cry1-2, Bmal1, Dbp, E4BP4, CK1varepsilon, PEPCK, PDK4 and NHE3, were altered in the livers and/or kidneys.

CONCLUSIONS

These results indicate that obesity induced by high-fat diet alters the circadian-clock system, and obesity and metabolic syndrome are highly correlated with the expressions of circadian-clock genes and their downstream, circadian clock-controlled genes.

Chinese metabolic syndrome risk score

BACKGROUND

The metabolic syndrome (MetS) was first proposed to predict the occurrence of cardiovascular disease and type 2 diabetes. However, it is difficult to identify subjects with MetS early. No previous studies designed to develop a predictive model for MetS in the Chinese population exists; this study was designed to fill that gap.

METHODS

A middle-aged Chinese cohort of 198 men and 154 women were followed for two years. The binary logistic regression and receiver operation characteristic (ROC) curve were used to develop a predictive model for the future development of MetS.

RESULTS

Over two years of follow up, 30 of the 352 subjects (8.52%) without MetS at baseline subsequently developed MetS. Triglycerides (TG) had the highest area under the curve (AUC), while diastolic blood pressure had the lowest. In order to increase the prediction power, MetS components were arranged in the ROC model according to their AUC. After adding waist circumference (WC) to TG (model 1), the AUC was significantly higher than for TG alone. Adding other components into the model did not increase the AUC significantly. A risk score cutoff (0.078) was selected for the best predictive power of model 1 (sensitivity of 76.7%, specificity of 63.4%, with AUC of 76.8%).

CONCLUSIONS

These results imply that WC and TG are related to the pathophysiologies of MetS, and model 1 could also be used clinically for screening subjects at high risks for MetS.

A water-soluble extract from Grifola frondosa, maitake mushroom, decreases lipid droplets in brown adipocyte tissue cells

We investigated the effect of a water-soluble extract from Grifola frondosa, the maitake mushroom, on lipid droplets in brown adipocyte tissue (BAT) cells. This water-soluble extract inhibits the conversion of pre white adipocyte tissue (WAT) cells but does not inhibit that of pre BAT cells. It reduces the amount of accumulated triglycerides (TG) in BAT cells. The glycerol-3-phosphate dehydrogenase (GPDH) activities of BAT cells decreased, but the expression of uncoupling protein 1 (UCP1) levels increased. These results suggest that maitake extract inhibits TG accumulation-related energy metabolism.

Effect of weight loss on markers of triglyceride-rich lipoprotein metabolism in the metabolic syndrome

BACKGROUND

Hypertriglyceridaemia, a consistent feature of dyslipidaemia in the metabolic syndrome (MetS), is related to the extent of abdominal fat mass and altered adipocytokine secretion. We determined the effect of weight loss by dietary restriction on markers of triglyceride-rich lipoprotein (TRL) metabolism and plasma adipocytokines.

DESIGN

Thirty-five men with MetS participated in a 16 week randomized controlled dietary intervention study. Apolipoprotein (apo) C-III, apoB-48, remnant-like particle (RLP)-cholesterol, total adiponectin, high-molecular weight (HMW) adiponectin, and retinol-binding protein-4 (RBP-4) concentrations were measured using immunoassays.

RESULTS

Compared with weight maintenance (n = 15), weight loss (n = 20) significantly decreased body weight, plasma insulin, triglycerides, total cholesterol, low-density lipoprotein (LDL)-cholesterol and lathosterol (P < 0.05). Weight loss also decreased plasma concentrations of apoC-III (-33%), apoB-48 (-37%), very low-density lipoprotein (VLDL)-apoB (-43%), RLP-cholesterol (-48%), and RBP-4 (-20%), and significantly increased plasma total (+20%) and HMW-adiponectin (+19%) concentrations. In the weight loss group, reduction in plasma apoC-III was associated (P < 0.05) with reduction in plasma apoB-48, VLDL-apoB, RLP-cholesterol and triglycerides. Increase in total adiponectin was associated (P < 0.05) with the reduction in plasma VLDL-apoB and triglycerides. The changes in HMW-adiponectin and RBP-4 were not associated with changes in plasma apoB-48, apoC-III, VLDL-apoB, RLP-cholesterol or triglycerides. In multiple regression analysis including changes in visceral fat, insulin and total adiponectin concentrations, the fall in plasma apoC-III concentration was an independent predictor of the reductions in plasma apoB-48, VLDL-apoB, RLP-cholesterol and triglycerides concentrations.

CONCLUSIONS

In men with MetS, weight loss decreases the plasma concentrations of apoB-48, VLDL-apoB, RLP-cholesterol and triglycerides. This effect could partly relate to concomitant changes in plasma apoC-III and adiponectin concentrations that accelerate the catabolism of TRLs.

Effects of a 1,3-diacylglycerol oil-enriched diet on postprandial lipemia in people with insulin resistance

Postprandial hypertriglyceridemia is common in individuals with insulin resistance, and diets enriched in 1,3-diacylglycerol (DAG) may reduce postprandial plasma triglycerides (PPTGs). We enrolled 25 insulin-resistant, nondiabetic individuals in a double-blind, randomized crossover trial to test the acute and chronic effects of a DAG-enriched diet on PPTG. Participants received either DAG or triacylglycerol (TAG) oil, in food products, for 5 weeks. Fasting lipids, and two separate postprandial tests, one with DAG oil and one with TAG oil, were performed at the end of each 5 week diet period. We found no acute or chronic effects of DAG oil on PPTG. Thus, neither the DAG oil PPTG (h/mg/dl) on a chronic TAG diet [area under the curve (AUC) = 503 +/- 439] nor the TAG oil PPTG on a chronic DAG diet (AUC = 517 +/- 638) was different from the TAG oil PPTG on a chronic TAG diet (AUC = 565 +/- 362). Five weeks of a DAG-enriched diet had no acute or chronic effects on PPTG in insulin-resistant individuals. We suggest further studies to evaluate the effects of DAG on individuals with low and high TG levels.

Dietary 1,3-diacylglycerol protects against diet-induced obesity and insulin resistance

To investigate the effect of dietary 1,3-diacylglycerol (DAG) on the development of insulin resistance (IR) and obesity, brown adipose tissue-deficient mice, a model of high-fat diet-induced IR and obesity, were fed Western-type diets (WTD) containing either DAG oil (n = 8) or standard triacylglycerol (TAG) oil (n = 9) for 15 weeks, beginning at 8 weeks of age. Although brown adipose tissue-deficient mice became obese on both TAG- and DAG-enriched WTD (TAG-WTD and DAG-WTD), the mice eating DAG-WTD gained less weight and had less body fat accumulation. The results of glucose tolerance tests conducted after 5 weeks of each WTD were not different. However, after 10 weeks of each WTD, impaired glucose tolerance developed in the TAG-WTD group but was prevented by DAG-WTD. Exploratory analyses of gene expression suggested that consumption of DAG-WTD was associated with reduced phosphoenolpyruvate carboxykinase gene expression in liver and increased expression of the genes for peroxisome proliferator-activated receptor alpha, lipoprotein lipase, and uncoupling proteins 2 and 3 in skeletal muscle. There were no effects of the DAG-WTD on fasting and postprandial plasma triglyceride (TG) levels, hepatic TG content, or the rate of secretion of TG from the liver. These findings suggest that diets enriched in 1,3-DAG oil may reduce WTD-induced IR and body fat accumulation by suppressing gluconeogenesis in liver and stimulating fat oxidation in skeletal muscle.

Evaluation of Insulin Resistance and Sodium Sensitivity in Normotensive Offspring of Hypertensive Individuals

BACKGROUND

Sodium sensitivity (SS) and insulin resistance (IR) might be a common link in the pathogenesis of essential hypertension. The aim of the present study is to investigate the relationship, if any, between SS and IR in a population with a family predisposition to develop hypertension.

METHODS

Twenty normotensive subjects aged 20 to 40 years with a family history of hypertension (1 or both parents hypertensive) and no other risk factor (group A) and 10 normotensive subjects aged 20 to 40 years without a family history of hypertension (group B) were enrolled. SS and IR were estimated using the euglycemic clamp technique and correlated in both groups. Blood pressure, mean blood pressure (MAP), and biochemical control were recorded.

RESULTS

The frequency of SS was equal in offspring of hypertensive subjects and the control group. Individuals with a family history of hypertension had a tendency to develop IR (45%) compared with the control group (20%). This group had a greater MAP at both salt-loading and salt-deprivation periods. Increased IR was associated with increased MAP. No significant relationship was found between SS and IR in either the entire sample or the subgroup of individuals with a family history of hypertension. Serum urea and total cholesterol levels were significantly greater in group A. Age, sex, and body mass index were not related to the presence of IR or SS in either group.

CONCLUSION

SS and IR do not relate in young normotensive adults or offspring of hypertensive parents. However, the latter may comprise a high-risk group, currently normotensive, who have an increased possibility to present or develop IR in early adolescent life. Moreover, the increased IR is related to the greater MAP in group A. Thus, they are subject to increased cardiovascular risk because of the subsequent disturbed glucose and lipid metabolism.

Metabolic syndrome and progression of atherosclerosis among middle-aged US adults

Metabolic syndrome, indicated by insulin resistance/hyperinsulinemia, obesity, central obesity, atherogenic dyslipidemia, and hypertension, contributes to atherosclerotic cardiovascular disease. However, it is controversial whether the indicators of metabolic syndrome are related to subclinical atherosclerosis collectively or individually. Whether there is any gender-based difference in the mechanisms of metabolic syndrome-induced atherosclerosis progression is also unknown. Two models were compared in this study. Model 1 assumes that a latent factor, metabolic syndrome per se, impacts subclinical atherosclerosis (collective effects model); Model 2 assumes the effect of the syndrome is mediated through its indicators (individual effects model). Data were obtained from the Los Angeles Atherosclerosis Study. The cohort consists of 573 adults (age, 40-60 years) who were asymptomatic for cardiovascular disease. Subclinical atherosclerosis was assessed by measuring common carotid artery intima-media thickness (CCA-IMT) using B-mode ultrasound. Three examinations were completed at 1.5-year intervals from 1995-1999. The analyses were performed with SAS 8.2 and AMOS 4.0. The results showed that atherogenic effects of metabolic syndrome were mediated through its indicators; there were gender-based differences in the mechanisms of metabolic syndrome-induced atherosclerosis. Central obesity was significantly associated with the baseline IMT for men only, whereas triglycerides were significantly associated with the progression of IMT for women only. Systolic blood pressure was significantly associated with the baseline and progression for both men and women. However, fasting insulin was not found to be significantly associated with the baseline and progression of IMT in the multivariate model, although it was significantly associated with other components of metabolic syndrome.

Lipid and lipoprotein dysregulation in insulin resistant states

Insulin resistant states are commonly associated with an atherogenic dyslipidemia that contributes to significantly higher risk of atherosclerosis and cardiovascular disease. Indeed, disorders of carbohydrate and lipid metabolism co-exist in the majority of subjects with the "metabolic syndrome" and form the basis for the definition and diagnosis of this complex syndrome. The most fundamental defect in these patients is resistance to cellular actions of insulin, particularly resistance to insulin-stimulated glucose uptake. Insulin insensitivity appears to cause hyperinsulinemia, enhanced hepatic gluconeogenesis and glucose output, reduced suppression of lipolysis in adipose tissue leading to a high free fatty acid flux, and increased hepatic very low density lipoprotein (VLDL) secretion causing hypertriglyceridemia and reduced plasma levels of high density lipoprotein (HDL) cholesterol. Although the link between insulin resistance and dysregulation of lipoprotein metabolism is well established, a significant gap of knowledge exists regarding the underlying cellular and molecular mechanisms. Emerging evidence suggests that insulin resistance and its associated metabolic dyslipidemia result from perturbations in key molecules of the insulin signaling pathway, including overexpression of key phosphatases, downregulation and/or activation of key protein kinase cascades, leading to a state of mixed hepatic insulin resistance and sensitivity. These signaling changes in turn cause an increased expression of sterol regulatory element binding protein (SREBP) 1c, induction of de novo lipogensis and higher activity of microsomal triglyceride transfer protein (MTP), which together with high exogenous free fatty acid (FFA) flux collectively stimulate the hepatic production of apolipoprotein B (apoB)-containing VLDL particles. VLDL overproduction underlies the high triglyceride/low HDL-cholesterol lipid profile commonly observed in insulin resistant subjects.

REVIEW: Efficacy and mechanisms of action of statins in the treatment of diabetic dyslipidemia

CONTEXT

The Adult Treatment Panel III recommends 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, or statins, as first-line lipid-altering therapy for all adult patients with diabetes mellitus. This is based on the well-characterized efficacy and safety profiles of this class of agents as well as several clinical trials demonstrating that statin treatment reduces the risk of cardiovascular events.

EVIDENCE ACQUISITION

This review provides an overview of the effectiveness and mechanisms of action of statins in patients with diabetes mellitus using small efficacy trials and large clinical outcomes trials as well as studies of the effects of statins on apolipoprotein B (apoB) metabolism.

EVIDENCE SYNTHESIS

The major findings presented are a review of mechanistic studies of selected subjects with diabetes mellitus and dyslipidemia and a compilation of results from large-scale clinical trials of patients with diabetes.

CONCLUSIONS

Statins are highly efficacious as low-density lipoprotein cholesterol-lowering agents and have more modest effects on very low-density lipoprotein triglyceride and high-density lipoprotein cholesterol levels. The effects of statins on plasma lipids and lipoproteins result from their ability to both increase the efficiency with which very low-density lipoprotein and low-density lipoprotein are cleared from the circulation and reduce the production of apoB-containing lipoproteins by the liver. Additional investigations are needed to clarify the mechanisms by which statins reduce apoB secretion from the liver.

[Correlation between the various measurements of obesity and the degree of resistance to insulin]

OBJECTIVE

To determine the correlation between certain obesity measurements and insulin resistance (measured by HOMA).

DESIGN

Descriptive cross-sectional study.

SETTING

Urban health centre with elderly population.

PARTICIPANTS

A random sample of 70 people was chosen from among an adult population with risk factors for DM2 or already diagnosed.

MAIN MEASUREMENTS

Parameters of obesity were collected (weight, BMI, body perimeters, waist/hip index, and cutaneous folds), as were clinical parameters (blood pressure and cardiovascular risk), and analyses (glycaemia and insulinaemia--both basal and after 2 hours of oral overload of glucose--, HOMA, lipid profile, and microalbuminuria study). Resistance to insulin (IR) was defined as a HOMA > or =3.8.

RESULTS

Individuals with IR had significantly higher values of weight (85.5 vs 75.5 kg), BMI (35.1 vs 29.4 kg/m2), waist perimeter (108 vs 100.3 cm) than those without IR. In neither group were any significant differences as to the waist/hip index found. The BMI and/or waist perimeter values that were more likely to suffer IR were established. In men, the values were waist >107 cm (sensitivity, 43%; specificity, 62%) and BMI>29 (sensitivity, 57%; specificity, 50%). In women, they were a waist >102 cm (sensitivity, 64%; specificity, 89%) and BMI>34 (sensitivity, 91%; specificity, 89%).

CONCLUSIONS

In clinical practice the BMI and the diameter of the waist are very good predictors of IR, whilst the waist/hip index and cutaneous folds do not provide any information of value.

Treatment with high-dose simvastatin reduces secretion of apolipoprotein B-lipoproteins in patients with diabetic dyslipidemia

HMG-CoA reductase inhibitors (statins) are effective lipid-altering drugs for the treatment of dyslipidemia in patients with type 2 diabetes mellitus. We conducted a randomized, double-blind, placebo-controlled, crossover design trial to determine the effects of simvastatin, 80 mg/day, on plasma lipid and lipoprotein levels and on the metabolism of apolipoprotein B (apoB) in VLDL, intermediate density lipoprotein (IDL), and LDL and of triglycerides (TGs) in VLDL. Simvastatin therapy decreased TG, cholesterol, and apoB significantly in VLDL, IDL, and LDL. These effects were associated with reduced production of LDL-apoB, mainly as a result of reduced secretion of apoB-lipoproteins directly into the LDL density range. Statin therapy also reduced hepatic production of VLDL-TG. There were no effects of simvastatin on the fractional catabolic rates of VLDL-apoB or -TG or LDL-apoB. The basis for decreased VLDL-TG secretion during simvastatin treatment is not clear, but recent studies suggest that statins may activate peroxisomal proliferator-activated receptor alpha (PPARalpha). Activation of PPARalpha could lead to increased hepatic oxidation of fatty acids and less synthesis of TG for VLDL assembly.

Does pravastatin increase chylomicron remnant catabolism in postmenopausal women with type 2 diabetes mellitus?

OBJECTIVE

We investigated the effects of pravastatin on chylomicron remnant catabolism measured with a 13C stable isotope breath test and plasma apolipoprotein (apo) B-48 and remnant-like particle (RLP)-cholesterol in postmenopausal women with type 2 diabetes mellitus.

PATIENTS AND MEASUREMENTS

Nineteen postmenopausal women with type 2 diabetes were randomized to receive 40 mg/day pravastatin or no treatment for 6 weeks followed by a 2-week washout period, and crossed over for a further 6 weeks. Fractional catabolic rate (FCR) of a chylomicron remnant-like emulsion was determined from 13CO2 enrichment in the breath and plasma using isotope-ratio mass spectrometry and multicompartmental modelling. Plasma apo B-48 and RLP-cholesterol concentrations were also measured as static markers of chylomicron remnant metabolism.

RESULTS

Pravastatin significantly reduced plasma concentrations of cholesterol (5.9 +/- 0.3 vs. 4.8 +/- 0.2 mmol/l; P < 0.001), low density lipoprotein (LDL)-cholesterol (3.5 +/- 0.2 vs. 2.6 +/- 0.2 mmol/l; P < 0.001), triglyceride (2.1 +/- 0.3 vs. 1.7 +/- 0.2 mmol/l; P = 0.017), non-high density lipoprotein (HDL)-cholesterol (4.4 +/- 0.3 vs. 3.3 +/- 0.2 mmol/l; P < 0.001), lathosterol/total cholesterol ratio (2.6 +/- 0.2 vs. 2.0 +/- 0.3, P = 0.035), apo B-100 (1.1 +/- 0.1 vs. 0.8 +/- 0.1 g/l; P = 0.001), apo B-48 (4.8 +/- 0.9 vs. 3.3 +/- 0.6 mg/l; P = 0.016), and RLP-cholesterol (31.4 +/- 8.2 vs. 18.6 +/- 4.6 mg/dl; P = 0.024). Pravastatin was also associated with an increase in sitosterol/total cholesterol ratio (2.8 +/- 0.3 vs. 3.1 +/- 0.3, P = 0.029). Chylomicron remnant-like emulsion catabolism was not, however, significantly altered by pravastatin estimated by either breath or plasma clearance measurements.

CONCLUSIONS

In postmenopausal women, pravastatin decreases plasma concentrations of remnant lipoproteins by a mechanism that may relate chiefly to inhibition of remnant production, but this requires further evaluation.

Effects of the PPARgamma agonist pioglitazone on lipoprotein metabolism in patients with type 2 diabetes mellitus

Elevated plasma levels of VLDL triglycerides (TGs) are characteristic of patients with type 2 diabetes mellitus (T2DM) and are associated with increased production rates (PRs) of VLDL TGs and apoB. Lipoprotein lipase-mediated (LPL-mediated) lipolysis of VLDL TGs may also be reduced in T2DM if the level of LPL is decreased and/or the level of plasma apoC-III, an inhibitor of LPL-mediated lipolysis, is increased. We studied the effects of pioglitazone (Pio), a PPARgamma agonist that improves insulin sensitivity, on lipoprotein metabolism in patients with T2DM. Pio treatment reduced TG levels by increasing the fractional clearance rate (FCR) of VLDL TGs from the circulation, without changing direct removal of VLDL particles. This indicated increased lipolysis of VLDL TGs during Pio treatment, a mechanism supported by our finding of increased plasma LPL mass and decreased levels of plasma apoC-III. Lower apoC-III levels were due to reduced apoC-III PRs. We saw no effects of Pio on the PR of either VLDL TG or VLDL apoB. Thus, Pio, a PPARgamma agonist, reduced VLDL TG levels by increasing LPL mass and inhibiting apoC-III PR. These 2 changes were associated with an increased FCR of VLDL TGs, almost certainly due to increased LPL-mediated lipolysis.