Clustering of metabolic abnormalities in obese individuals: the role of genetic factors

Testing of a model for risk factors for eating disorders and higher weight among emerging adults: Baseline evaluation

Although a range of risk factors have been identified for disordered eating and weight status, the breadth of risk factors have been rarely considered within a single, comprehensive model. The robustness of these findings across countries also remains an open question. The present study sampled 6272 participants aged 18-30 years from eight countries in an attempt to evaluate combined and unique predictors for these two conditions, and to explore possible cross-country differences in these models. Participants completed a range of demographic, biological, behavioral, psychological, and sociocultural measures to test a comprehensive model of the contributions of these predictors for disordered eating and weight-related constructs (binge eating, body mass index, compensatory behaviors, dietary restraint, drive for muscularity, and drive for leanness). Structural invariance testing within a multigroup path analysis framework revealed that a single model across the eight countries provided poor model fit. Freeing of 22% of parameters across countries provided excellent fit and a satisfactory compromise for country-invariant and country-variant parameters in the model. Overall, predictors accounted for between 15% and 60% of variance in the outcome measures, with lowest explained variance for the disordered eating outcomes. Significant unique contributions to prediction were observed for each of the five risk factor variable types and across the eight countries. Thus, the findings show strong support for this model as an explanatory framework of both disordered eating and weight status.

Association of Metabolic Syndrome with Aerobic Exercise and LPL rs3779788 Polymorphism in Taiwan Biobank Individuals

PURPOSE

The Lipoprotein lipase (LPL) gene is a significant contributor to dyslipidemia. It has shown associations with several conditions including atherosclerosis, obesity, and metabolic syndrome (MetS). We assessed the interactive association between MetS and rs3779788 of the LPL gene based on aerobic exercise.

MATERIALS AND METHODS

Data were available for 7532 Taiwan Biobank (TWB) participants recruited between 2008 and 2016. We used multiple logistic regression to determine the odds ratios (OR) for MetS and their 95% confident intervals (C.I.). Potential variables included LPL rs3779788, aerobic exercise, sex, age, education, marital status, body mass index (BMI), smoking, alcohol consumption, midnight snacking, vegetarian diet, coffee, dietary fat, and tea drinking.

RESULTS

Aerobic exercise was protective against MetS (OR, 0.858; 95% C.I., 0.743-0.991). Compared to CC/CT genotype, the OR for developing MetS was 0.875, (95% C.I., 0.571-1.341) in TT individuals. The test for interaction was significant for the rs3779788 variant and aerobic exercise (p = 0.0484). In our group analyses, the OR for MetS was 0.841 (95% C.I., 0.727-0.974) in CC/CT and 4.076 (95% C.I., 1.158-14.346) in TT individuals who did aerobic exercise compared to those who did not.

CONCLUSION

Our study indicated that aerobic exercise improved metabolic syndrome in Taiwanese adults with rs3779788 CC/CT genotype relative to those with TT genotype.

Association analysis of polymorphisms in LEP (rs7799039 and rs2167270) and LEPR (rs1137101) gene towards the development of type 2 diabetes in North Indian Punjabi population

OBJECTIVES

Obesity is a major risk factor in aetiology of type 2 diabetes mellitus (T2DM). Leptin (LEP) is an anti-obesity hormone which regulates food intake, energy expenditure and glucose metabolism. The genetic variants in leptin and leptin receptor gene (LEPR) may play major role in the pathogenesis of T2DM and obesity. The current study aimed to investigate the association of polymorphisms in LEP (rs7799039, -2548G/A and rs2167270, 19G/A) and LEPR (rs1137101, 668A/G) gene with type 2 diabetes in North Indian Punjabi population.

METHODS

A total of 817 subjects were included for the present case-control study, consisting of 417 T2DM patients and 400 healthy controls. The anthropometric, physiometric and biochemical measurements were taken from all the subjects. The genotyping of LEP and LEPR gene variants were carried out by polymerase chain reaction based restriction fragment length polymorphism method (PCR-RFLP), followed by genotyping of 10% of the samples for each polymorphism by Sanger sequencing method for quality control measurement.

RESULTS

The risk genotype frequencies were found to be significantly higher in T2DM cases than control subjects (rs7799039, p = 0.001; rs2167270, p = 0.019 and rs1137101, p = 0.003). Under recessive genetic model LEPrs7799039 and LEPRrs1137101 polymorphism conferred 3.4 and 2.1 fold risk towards the development of T2DM after adjustment of various covariates (OR = 3.44, 95%CI: 1.768-6.681, p = 0.001 and OR: 2.12, 95%CI: 1.256-3.569, p = 0.005, respectively). In the stratified analysis of LEP variant rs7799039 by age, gender, BMI and alcohol use, a significantly increased risk of T2DM was found in female, BMI ≥ 23 and never drinking subgroups. However, in the LEPR variant rs1137101, significantly increased risk of T2DM was observed in age <50, male, BMI ≥ 23 and never drinking subgroup. The A-G haplotype combination of rs7799039A and rs2167270G conferred significant 2 fold risk towards T2DM (OR = 2.35, 95%CI: 1.34-4.12, p = 0.002). In control group, the genetic variants rs7799039 and rs1137101 were significantly associated with levels of random blood sugar and low density lipoprotein cholesterol levels.

CONCLUSION

The present study revealed the association of LEP rs7799039 and LEPR rs1137101 with type 2 diabetes mellitus, which suggest its predominant role in the estimation of type 2 diabetes mellitus in North Indian Punjabi population.

Insulin resistance, haemostatic factors and cardiovascular risk

Increased insulin resistance, which is present in the majority of type 2 diabetics patients, is associated with other metabolic and pro-coagulant cardiovascular risk factors and may account for the accelerated atherosclerosis and increased thrombotic potential observed in these patients. In individuals with normoglycaemia or impaired glucose tolerance (IGT), hyperinsulinaemia (a marker of insulin resistance) is associated with a similar clustering of risk factors and is predictive of cardiovascular events. The origins of insulin resistance are not well understood but data from families, twins and extended pedigrees suggest significant genetic and environmental contributions. The clustering of atherogenic traits begins in childhood, carries through to adult life and may result from the multiple effects of individual genes (pleiotropy) and environmental influences. Important environmental determinants of insulin resistance may occur before birth and, in conjunction with subsequent diet and exercise habits which result in obesity, lead to increased insulin resistance and cardiovascular risk. Therefore, primary prevention should centre around lifestyle changes which increase insulin sensitivity, maintain normoglycaemia and ameliorate atherothrombotic risk factor clustering.

The Role of Obesity in Preeclampsia

The incidence of obesity is increasing at an alarming rate. There is compelling evidence that obesity increases the risk of preeclampsia about 3-fold, and in developed countries is the leading attributable risk for the disorder. In this presentation we explore this relationship and propose targets for future studies guided by the much more extensively studied relationship of obesity to cardiovascular disease. We further address the hypothesis that asymmetric dimethyl arginine (ADMA), an endogenous inhibitor of nitric oxide synthase, may be one convergence point for the mechanism by which obesity increases the risk of preeclampsia. We conclude with consideration of the clinical implications of this information.

Characterization of clinical and genetic risk factors associated with dyslipidemia after kidney transplantation

We determined the prevalence of dyslipidemia in a Japanese cohort of renal allograft recipients and investigated clinical and genetic characteristics associated with having the disease. In total, 126 patients that received renal allograft transplants between February 2002 and August 2011 were studied, of which 44 recipients (34.9%) were diagnosed with dyslipidemia at 1 year after transplantation. Three clinical factors were associated with a risk of having dyslipidemia: a higher prevalence of disease observed among female than male patients (P = 0.021) and treatment with high mycophenolate mofetil (P = 0.012) and prednisolone (P = 0.023) doses per body weight at 28 days after transplantation. The genetic association between dyslipidemia and 60 previously described genetic polymorphisms in 38 putative disease-associated genes was analyzed. The frequency of dyslipidemia was significantly higher in patients with the glucocorticoid receptor (NR3C1) Bcl1 G allele than in those with the CC genotype (P = 0.001). A multivariate analysis revealed that the NR3C1 Bcl1 G allele was a significant risk factor for the prevalence of dyslipidemia (odds ratio = 4.6; 95% confidence interval = 1.8–12.2). These findings may aid in predicting a patient's risk of developing dyslipidemia.

Transgenerational effects of parental cardiovascular disease and risk factors on offspring mortality: family-linkage data from the HUNT Study, Norway

BACKGROUND

Cardiovascular risk factors are known to be associated between parents and offspring. However, whether these associations are reflected in increased offspring mortality has not been extensively studied.

DESIGN

This was a family study of 32,536 father-offspring and 39,614 mother-offspring pairs who participated in the HUNT Study, Norway.

METHODS

Adjusted hazard ratios (HRs) for offspring total and cardiovascular mortality associated with parental levels of cardiovascular disease risk factors were estimated using Cox regression.

RESULTS AND CONCLUSIONS

Fathers' and mothers' reporting of cardiovascular disease (HRs: 1.18; 95% CI 1.04-1.32 and 1.20; 1.07-1.35, respectively), diabetes (HRs: 1.22; 95% CI 1.00-1.49 and 1.21; 1.05-1.40, respectively), and current smoking (HRs: 1.21; 95% CI 1.08-1.36 and 1.30; 1.15-1.47, respectively) was associated with total mortality in offspring. An inverse association was found with maternal height (HR: 0.95; 95% CI 0.91-0.99), and a suggestive inverse association with paternal height (HR: 0.98; 95% CI 0.93-1.03). Relations with offspring cardiovascular mortality were less clear and consistent. Offspring whose parents both had a risk factor did not seem to have higher mortality than would be expected from the independent effects of each parent.

Inactivation of the adrenergic receptor β2 disrupts glucose homeostasis in mice

Three types of beta adrenergic receptors (ARβ1-3) mediate the sympathetic activation of brown adipose tissue (BAT), the key thermogenic site for mice which is also present in adult humans. In this study, we evaluated adaptive thermogenesis and metabolic profile of a mouse with Arβ2 knockout (ARβ2KO). At room temperature, ARβ2KO mice have normal core temperature and, upon acute cold exposure (4 °C for 4 h), ARβ2KO mice accelerate energy expenditure normally and attempt to maintain body temperature. ARβ2KO mice also exhibited normal interscapular BAT thermal profiles during a 30-min infusion of norepinephrine or dobutamine, possibly due to marked elevation of interscapular BAT (iBAT) and of Arβ1, and Arβ3 mRNA levels. In addition, ARβ2KO mice exhibit similar body weight, adiposity, fasting plasma glucose, cholesterol, and triglycerides when compared with WT controls, but exhibit marked fasting hyperinsulinemia and elevation in hepatic Pepck (Pck1) mRNA levels. The animals were fed a high-fat diet (40% fat) for 6 weeks, ARβ2KO mice doubled their caloric intake, accelerated energy expenditure, and induced Ucp1 expression in a manner similar to WT controls, exhibiting a similar body weight gain and increase in the size of white adipocytes to the WT controls. However, ARβ2KO mice maintain fasting hyperglycemia as compared with WT controls despite very elevated insulin levels, but similar degrees of liver steatosis and hyperlipidemia. In conclusion, inactivation of the ARβ2KO pathway preserves cold- and diet-induced adaptive thermogenesis but disrupts glucose homeostasis possibly by accelerating hepatic glucose production and insulin secretion. Feeding on a high-fat diet worsens the metabolic imbalance, with significant fasting hyperglycemia but similar liver structure and lipid profile to the WT controls.

Association of ghrelin Leu72Met polymorphism with type 2 diabetes mellitus in Chinese population

BACKGROUND

Ghrelin, a novel endogenous ligand for the growth hormone secretagogue receptor, is considered to implicate the development of the type 2 diabetes mellitus (T2DM). The Leu72Met (+408C>A) polymorphism of the preproghrelin, has been linked to obesity, insulin resistance and diabetes.

OBJECTIVE

To investigate the distribution of ghrelin gene Leu72Met polymorphism and its association with the type 2 diabetes mellitus in Chinese population.

METHODS

We conducted a case-control study on 877 patients with T2DM and 864 controls, which were genotyped by the polymerase chain reaction (PCR) technique, denaturing high performance liquid chromatography (DHPLC) and DNA sequence analysis. Laboratory analyses were carried out in the hospital laboratory.

RESULTS

No significant difference in the Leu72Met genotype distributions and allele frequency was observed between type 2 diabetes mellitus and controls (both P>0.05). The polymorphism was not associated with T2DM. However, among the T2DM group, the patients carrying Leu72Leu genotype had significantly increased levels of FPG and serum creatinine compared with variant genotypes (Leu72Met and Met72Met) (P<0.05). In the control group, the subjects with variant genotypes had significantly increased levels of FINS, HOMA-IR compared with Leu72Leu genotype (P<0.05).

CONCLUSION

The Leu72Met polymorphism of the preproghrelin gene was not associated with T2DM in Chinese population. However, it may have some roles in the etiology of insulin resistance.

Insulin resistance and epigenetic regulation: insights from human studies and prospects for future research

In this study, we review the current knowledge and recent insights on the role of epigenetic factors in the development of human insulin resistance (IR)- and metabolic syndrome (MS)-related phenotypes, and attempt to lay a framework to consider IR as a potentially reversible incapacity to control metabolic homeostasis that is strongly influenced by the interplay between external and internal cues. We summarize the evidence on how tissue-specific epigenetic markers participate either by activating or repressing the gene expression programs to modulate IR- and MS-associated traits. Some additional data are provided about how the exploration of DNA methylation markers in peripheral blood mononuclear cells potentially offers appealing information about the impact of epigenetics in the pathogenesis of IR. Clues about the relation between IR and impaired intrauterine growth explained by fetal metabolic programming and epigenetic modifications are shown, including novel findings about the impact of histone modifications. For instance, we observed that specific epigenetic factors in genes associated with mitochondrial biogenesis may be associated with birth weight. Furthermore, some prospective ideas about the functional consequences of genetic variation modulated by allele-specific epigenetic markers and its impact on MS susceptibility are also illustrated. Finally, we summarize the current knowledge of epigenetics as the biological rationale for potential therapeutic intervention in IR and MS.

Association of plasma epinephrine level with insulin sensitivity in metabolically healthy but obese individuals

In the present study, we explored the association of catecholamines with insulin sensitivity in "metabolically healthy but obese" (MHO) individuals, by examining the metabolic characteristics and plasma catecholamine levels in 100 obese, sedentary postmenopausal women. Subjects were classified as MHO (n=25) or at-risk (n=25) based on the upper and lower quartiles of insulin sensitivity as measured by the hyperinsulinemic-euglycemic clamp technique. The MHO group presented a significantly higher range of plasma epinephrine levels (73 ± 21 pg/mL) than the at-risk group (39 ± 20 pg/mL) (P<0.05), though both within the normal basal range of plasma epinephrine (56 ± 30 pg/mL). Multivariate regression analysis showed that high-sensitivity C-reactive protein, plasma epinephrine, triglycerides and lean body mass index were independent predictors of glucose disposal. The plasma epinephrine level was positively correlated with the glucose disposal rate, insulin sensitivity and the HDL-cholesterol level, and negatively correlated with the triglycerides level (P<0.05). In conclusion, this study for the first time demonstrates a positive association between plasma epinephrine level and insulin sensitivity in MHO individuals.

Ghrelin in Type 2 diabetes mellitus and metabolic syndrome

The increasing prevalence of metabolic syndrome and the consequent cardiovascular diseases, like atherosclerotic diseases and Type 2 diabetes has stimulated an active search for novel risk factors. The hormones regulating energy balance are of special interest as potential risk factors for metabolic syndrome and Type 2 diabetes. Ghrelin is a peptide hormone from stomach with growth hormone releasing activity. It is also able to modify glucose and insulin metabolism, blood pressure levels, adipogenesis, and inflammatory processes in experimental conditions. Whether ghrelin has a role in the development metabolic syndrome and the associated diseases, is not known. This review will report the evidence for the role of ghrelin in the clustering of the components of the metabolic syndrome.

Regular multicomponent exercise increases physical fitness and muscle protein anabolism in frail, obese, older adults

Aging is associated with a decline in strength, endurance, balance, and mobility. Obesity worsens the age-related impairment in physical function and often leads to frailty. The American College of Sports Medicine recommends a multicomponent (strength, endurance, flexibility, and balance) exercise program to maintain physical fitness. However, the effect of such an exercise program on physical fitness in frail, obese older adults is not known. We therefore determined the effect of a 3-month long multicomponent exercise training program, on endurance (peak aerobic capacity (VO(2) peak)), muscle strength, muscle mass, and the rate of muscle protein synthesis (basal rate and anabolic response to feeding) in nine 65- to 80-year-old, moderately frail, obese older adults. After 3 months of training, fat mass decreased (P < 0.05) whereas fat-free mass (FFM), appendicular lean body mass, strength, and VO(2) peak increased (all P < 0.05). Regular strength and endurance exercise increased the mixed muscle protein fractional synthesis rate (FSR) but had no effect on the feeding-induced increase in muscle protein FSR (~0.02%/h increase from basal values both before and after exercise training; effect of feeding: P = 0.02; effect of training: P = 0.047; no interaction: P = 0.84). We conclude that: (i) a multicomponent exercise training program has beneficial effects on muscle mass and physical function and should therefore be recommended to frail, obese older adults, and (ii) regular multicomponent exercise increases the basal rate of muscle protein synthesis without affecting the magnitude of the muscle protein anabolic response to feeding.

Variations in Adipokine Genes AdipoQ, Lep, and LepR are Associated with Risk for Obesity-Related Metabolic Disease: The Modulatory Role of Gene-Nutrient Interactions

Obesity rates are rapidly increasing worldwide and facilitate the development of many related disease states, such as cardiovascular disease, the metabolic syndrome, type 2 diabetes mellitus, and various types of cancer. Variation in metabolically important genes can have a great impact on a population's susceptibility to becoming obese and/or developing related complications. The adipokines adiponectin and leptin, as well as the leptin receptor, are major players in the regulation of body energy homeostasis and fat storage. This paper summarizes the findings of single nucleotide polymorphisms in these three genes and their effect on obesity and metabolic disease risk. Additionally, studies of gene-nutrient interactions involving adiponectin, leptin, and the leptin receptor are highlighted to emphasize the critical role of diet in susceptible populations.

Resistance training in the treatment of the metabolic syndrome: a systematic review and meta-analysis of the effect of resistance training on metabolic clustering in patients with abnormal glucose metabolism

Over the last decade, investigators have given increased attention to the effects of resistance training (RT) on several metabolic syndrome variables. The metabolic consequences of reduced muscle mass, as a result of normal aging or decreased physical activity, lead to a high prevalence of metabolic disorders. The purpose of this review is: (i) to perform a meta-analysis of randomized controlled trials (RCTs) regarding the effect of RT on obesity-related impaired glucose tolerance and type 2 diabetes mellitus; and (ii) to investigate the existence of a dose-response relationship between intensity, duration and frequency of RT and the metabolic clustering. Thirteen RCTs were identified through a systematic literature search in MEDLINE ranging from January 1990 to September 2007. We included all RCTs comparing RT with a control group in patients with abnormal glucose regulation. For data analysis, we performed random effects meta-analyses to determine weighted mean differences (WMD) with 95% confidence intervals (CIs) for each endpoint. All data were analysed with the software package Review Manager 4.2.10 of the Cochrane Collaboration. In the 13 RCTs included in our analysis, RT reduced glycosylated haemoglobin (HbA(1c)) by 0.48% (95% CI -0.76, -0.21; p = 0.0005), fat mass by 2.33 kg (95% CI -4.71, 0.04; p = 0.05) and systolic blood pressure by 6.19 mmHg (95% CI 1.00, 11.38; p = 0.02). There was no statistically significant effect of RT on total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride and diastolic blood pressure. Based on our meta-analysis, RT has a clinically and statistically significant effect on metabolic syndrome risk factors such as obesity, HbA(1c) levels and systolic blood pressure, and therefore should be recommended in the management of type 2 diabetes and metabolic disorders.

Association of serum leptin levels with homeostasis model assessment-estimated insulin resistance and metabolic syndrome: the key role of central obesity

BACKGROUND

Leptin is correlated with several features of metabolic syndrome; however, possible confounders (eg, obesity) of this association are not known. This study evaluated the relationship between leptin, metabolic syndrome, and insulin resistance in an Iranian population and further investigated whether this relationship is confounded by obesity or central obesity.

METHODS

A total of 387 participants (18-65 years old) who referred to a large university general hospital for routine health examinations were categorized into 2 groups with (n = 130) and without (n = 257) metabolic syndrome. Fasting plasma glucose, insulin, lipids, and leptin levels were measured and the homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Metabolic syndrome was defined according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria.

RESULTS

Age- and sex-adjusted leptin levels were significantly higher in patients with than those without metabolic syndrome (29.62 +/- 1.67 vs. 18.50 +/- 1.21 ng/mL, P < 0.001). After adjustment for age, sex, and body mass index (BMI), leptin values were significantly correlated with HOMA-IR (P < 0.001), metabolic syndrome, and its components (P < 0.05). After adjustment for waist circumference, however, these associations were no longer statistically significant.

CONCLUSIONS

We demonstrated that high leptin levels are associated with insulin resistance and metabolic syndrome independent of BMI but these associations are significantly mediated through the effects of central obesity.

beta(3)-adrenergic receptor polymorphism and metabolic syndrome in postmenopausal women

OBJECTIVES

Some studies indicate that the Trp64Arg polymorphism in the gene encoding the beta(3)-adrenergic receptor (ADRB3) is associated with obesity, insulin resistance and earlier onset of type 2 diabetes mellitus. The aim of the present study was to evaluate the frequency of ADRB3 polymorphism and its association with metabolic syndrome in postmenopausal women.

METHODS

We performed the study on 284 randomly chosen postmenopausal women, aged 50-60 years, who were then selected to the study. Measurements of anthropometric parameters and biochemical estimations such as lipid profile, glucose and insulin level in serum were carried out using commercial kits. ADRB3 genotyping was performed by polymerase chain reaction and mini-sequencing.

RESULTS

The frequency of the Trp64/Arg64 genotype in the investigated population was 13%, and of the Trp64/Trp64 genotype, 85%. The Arg64/Arg64 genotype was present in only 2% of women. Metabolic syndrome was recognized in 22% of women bearing Trp64/Arg64 genotype and in 14% of women bearing Trp64/Trp64 genotype, without a statistically significant difference between the two groups (p > 0.05 in the chi(2) test). Women bearing the Trp64/Arg64 genotype had lower serum levels of high-density lipoprotein cholesterol (HDL-C) than Trp64/Trp64 genotype women (63.2 +/- 13.0 vs. 71.4 +/- 17.4 mg/dl). Both groups did not differ in any other investigated parameter.

CONCLUSION

Trp64Arg polymorphism of the beta(3)-adrenergic receptor gene is not related to metabolic syndrome in postmenopausal Polish women; however, it seems to be associated with decreased HDL-C levels.

Effects of dietary fibers on disturbances clustered in the metabolic syndrome

Because of its growing prevalence in Western countries, the metabolic syndrome, a common metabolic disorder that clusters a constellation of abnormalities, including central obesity, hypertension, dyslipidemia and insulin resistance, is emerging as one of the most important public health problems in the world, taking into account that it is a major risk factor mainly for type 2 diabetes and cardiovascular diseases, and also for many types of cancer. Although the pathogenesis of this syndrome is complex and not fully understood, obesity and insulin resistance, accompanied by an altered profile of number of hormones and cytokines produced by the adipose tissue, seem to be the main causative agents. A prime therapeutic approach to the prevention and treatment of this syndrome involves lifestyle changes. Among dietary modifications, dietary fiber intake could play an interesting role in the management of metabolic syndrome through different mechanisms related to its dietary sources, specific chemical structure and physical properties, or fermentability in the gut. According to all of these variables, the different types of dietary fibers have been reported to take part in the control of body weight, glucose and lipid homeostasis, insulin sensitivity and in the regulation of many inflammation markers involved in the pathogenesis of metabolic syndrome, and which are also considered to be among its features.

Leptin and high-sensitivity C-reactive protein and their interaction in the metabolic syndrome in middle-aged subjects

High-sensitivity C-reactive protein (hsCRP) and leptin, known to interact at the molecular level, have been associated with the metabolic syndrome (MS). We examined the independent and joint effects of high leptin and hsCRP levels on the development of MS in a population-based cohort of middle-aged subjects (N = 1035). Leptin and hsCRP levels increased with an increase in the number of metabolic abnormalities (P < .001). However, additional adjustment for body mass index diluted the association of leptin with MS in women. In men, the association of high leptin with insulin resistance and waist circumference (P < .001), and in women, the association of high hsCRP with insulin resistance (P = .029) and waist circumference (P = .009) persisted in the multivariate logistic regression models. High leptin in men and high hsCRP in women were significant predictors of MS in logistic regression analysis (P < .001). The highest prevalence of MS (86% in men and 71% in women) was observed in the subjects who belonged to the highest quartile in both leptin and hsCRP. MS is associated independently with high leptin in men and with hsCRP in women, whereas individuals with both of these markers belong to the highest risk of metabolic cluster. The study suggests sex-specific interplay between metabolic and inflammatory markers in the pathogenesis of MS.

The modulation of STAT5A/GR complexes during fat cell differentiation and in mature adipocytes

OBJECTIVE

Signal transducer and activator of transcription (STAT) 5A has been shown to interact with the glucocorticoid receptor (GR) in adipocytes. The aim of this study was to investigate the subcellular locations and modulation of STAT5A/GR complexes during adipogenesis and in mature adipocytes.

RESEARCH METHODS AND PROCEDURES

Both 3T3-L1 and 3T3-F442A cells were studied by performing subcellular fractionations, immunoprecipitation, and Western blotting after various treatments.

RESULTS

The formation of nuclear STAT5A/GR complexes was regulated in the cytosol and in the nucleus at distinct times during adipogenesis and in mature adipocytes. STAT5A, but not STAT5B, forms a complex with GR in adipocytes. The STAT5A associated with GR in the nucleus is tyrosine phosphorylated.

DISCUSSION

The association of STAT5A with GR in the nucleus of adipocytes is modulated by the tyrosine phosphorylation of STAT5A. Both GR and STAT5A are known to have important roles in adipocyte function. Hence, our data suggest that the association of these two transcription factors may be important in the regulation of adipocyte gene expression.

Low plasma ghrelin concentration is an indicator of the metabolic syndrome

BACKGROUND

Low ghrelin concentration has been associated with several features of metabolic syndrome (MS), but the relationship between ghrelin concentration and MS as a cluster of metabolic aberrations has not yet been studied.

AIMS OF THE STUDY

To analyse whether ghrelin concentration is associated with MS.

RESEARCH DESIGN AND METHODS

Fasting plasma ghrelin concentrations of the population-based cohort of 1037 middle-aged men and women were analysed using a commercial radioimmunoassay kit (Phoenix Peptide). MS was determined using the new International Diabetes Federation criteria.

RESULTS

The prevalence of MS was 37.2%. The ghrelin concentrations were decreased in subjects with MS (635 pg/mL) compared to those without MS (687 pg/mL) (P=0.001). Ghrelin levels decreased with an increase in the number of metabolic abnormalities. Low ghrelin was a statistically significant predictor of MS in logistic regression analysis (P=0.005) so that the subjects in the 1st ghrelin quartile were at higher risk of having MS compared to the subjects in the 4th quartile (OR=1.82, 95% CI: 1.27-2.60, P=0.001). This association remained statistically significant after adjustment for age and sex (OR=1.76, 95% CI: 1.24-2.55, P=0.002).

CONCLUSIONS

Metabolic syndrome is associated with low ghrelin levels suggesting a relationship of ghrelin in the metabolic disturbances of MS.

Beta2-adrenoceptor gene polymorphisms

Beta2-adrenoceptors (AR) play an important role in regulation of vascular and bronchial smooth muscle tone; functional beta2-AR, however, also exist in human heart where they can mediate positive inotropic and chronotropic effects. Recent studies have discovered that beta2-AR are polymorphic. The most common single nucleotide polymorphisms (SNPs) are: Arg16Gly, Gln27Glu, Thr164Ile in the coding region, and Arg-19Cys in the 5' upstream peptide. These SNPs affect receptor function in vitro; however, conflicting data exist on their functional relevance in vivo. This might be due to the fact that the four SNPs in the 5' upstream peptide and in the coding region, respectively, are linked and form certain haplotypes. This review gives an overview on the contribution of beta2-AR polymorphisms to cardiovascular diseases or altered drug responses. In addition, the relevance of SNPs vs. haplotypes for beta2-AR functional responsiveness is discussed.

Genetic and environmental influences of surfactant protein D serum levels

The collectin surfactant protein D (SP-D) is an important component of the pulmonary innate immune system, but SP-D is also present on extrapulmonary epithelial surfaces and in serum, where it has been used as a biomarker for pulmonary disease states. In this study, we investigate the mechanisms defining the constitutional serum level of SP-D and determine the magnitude of the genetic contribution to serum SP-D in the adult population. Recent studies have demonstrated that serum SP-D concentrations in children are genetically determined and that a single nucleotide polymorphism (SNP) located in the NH(2)-terminal region (Met11Thr) of the mature protein is significantly associated with the serum SP-D levels. A classic twin study was performed on a twin population including 1,476 self-reported healthy adults. The serum SP-D levels increased with male sex, age, and smoking status. The intraclass correlation was significantly higher for monozygotic (MZ) twin pairs than for dizygotic (DZ) twin pairs. Serum SP-D variance was influenced by nonshared environmental effects and additive genetic effects. Multivariate analysis of MZ and DZ covariance matrixes showed significant genetic correlation among serum SP-D and metabolic variables. The Met11Thr variant explained a significant part of the heritability indicating that serum SP-D variance could be decomposed into non-shared environmental effects (e(2) = 0.19), additive genetic effects (h(2) = 0.42), and the effect of the Met11Thr variations (q(2) = 0.39).

Factor analysis of lifestyle-related factors in 12,525 urban Japanese subjects

This study describes the clustering patterns of several lifestyle-related factors in urban Japanese subjects. The effect of aging on these patterns was also investigated. Data of 8 factors that included body mass index (BMI), blood pressure (BP), fasting plasma glucose (FPG), serum total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDLc), gamma-glutamyl-transferase (GGT), and cigarette smoking were analyzed for 12,525 individuals (4,591 men and 7,934 women) aged either 40, 50, or 60 years. Factor analysis showed eight factors clustered into 3 unrelated groups. BMI and BP were excluded in subjects aged 60 years. Our data showed that the effect of obesity on the prevalence of type 2 diabetes mellitus was age dependent. In spite of the established inverse relationship between TG and HDLc, we found that TG had an association with GGT. These results indicated that aging may have a major influence on the expression of multiple risk factors. The influence of BMI on the lifestyle-related factors appeared to be mostly expressed in younger people, while these factors appeared to be independent of BMI at age 60.

Exercise training increases electron and substrate shuttling proteins in muscle of overweight men and women with the metabolic syndrome

Aerobic conditioned muscle shows increased oxidative metabolism or glucose relative to untrained muscle at a given absolute exercise intensity. The studies of a targeted risk reduction intervention through defined exercise (STRRIDE) study is an aerobic exercise intervention in men and women with features of metabolic syndrome (Kraus WE, Torgan CE, Duscha BD, Norris J, Brown SA, Cobb FR, Bales CW, Annex BH, Samsa GP, Houmard JA, and Slentz CA, Med Sci Sports Exerc 33: 1774–1784, 2001), with four muscle biopsies taken during training and detraining time points. Here, we expanded a previous study (Hittel DS, Kraus WE, and Hoffman EP, J Physiol 548: 401–410, 2003) and used mRNA profiling to investigate gene transcripts associated with energy and substrate metabolism in STRRIDE participants. We found coordinate regulation of key metabolic enzymes with aerobic training in metabolic syndrome (aspartate aminotransferase 1, lactate dehydrogenase B, and pyruvate dehydrogenase-α1). All were also quickly downregulated by detraining, although the induction was not an acute response to activity. Protein and enzymatic assays were used to validate mRNA induction with aerobic training and loss with detraining (96 h to 2 wk) in 10 male and 10 female STRRIDE subjects. We propose that training coordinately increases the levels of aspartate aminotransferase 1, lactate dehydrogenase B, and pyruvate dehydrogenase-α1subunit, increasing glucose metabolism in muscle by liberating pyruvate for oxidative metabolism and, therefore, limiting lactate efflux. Serial measurement of fasting plasma lactate from 62 subjects from the same exercise group demonstrated a significant decrease of circulating lactate with training. We also found evidence for sex-specific molecular remodeling of muscle with ubiquinol-cytochrome c reductase core protein II, a component of mitochondrial respiratory complex III, which showed an increase after training that was specific to women. These biochemical adaptations complement existing molecular models for improved glucose tolerance with exercise intervention in prediabetic individuals.

Gain of Function Mutation in the Mineralocorticoid Receptor of the Brown Norway Rat

The aim of this research was to identify the molecular bases of differences in sensitivity to corticosteroid hormones between Brown Norway and Fischer 344 rats. We previously showed an apparent insensitivity to adrenalectomy in Brown Norway rats. Based on our first hypothesis of a different activity/reactivity of the mineralocorticoid signaling pathway between the two rat strains, we sequenced Brown Norway and Fischer 344 mineralocorticoid receptor cDNA and identified a tyrosine to cysteine substitution (Y73C) in the N-terminal part of the Brown Norway mineralocorticoid receptor. As a first step, this substitution gave us a means to distinguish the Brown Norway allele from the Fischer 344 at the mineralocorticoid receptor locus in an F2 population. We showed a strong genetic linkage between the mineralocorticoid receptor genotype and sensitivity to adrenalectomy. A subsequent genome-wide linkage analysis confirmed the involvement of the mineralocorticoid receptor locus and implicated other loci, including one on chromosome 4, which collectively explain a large part of the strain differences in corticosteroid receptor responses. In vitro studies further revealed that the Y73C substitution induces greater transactivation of the mineralocorticoid receptor by aldosterone, and surprisingly by progesterone as well, which could substitute for aldosterone after adrenalectomy in Brown Norway rats. We challenged this hypothesis in vivo and showed that plasma progesterone is higher in Brown Norway male rats and partially compensates for aldosterone after adrenalectomy. This work illustrates the interest of a pluristrategic approach to explore the mineralocorticoid receptor signaling pathway and its implication in the regulation of hydroelectrolytic homeostasis and blood pressure.

Diet, diabetes and schizophrenia: review and hypothesis

BACKGROUND

Diabetes is more common in people with schizophrenia than in the general population.

AIMS

To explore the possible reasons for the association between diabetes and schizophrenia.

METHOD

Diet and other lifestyle factors in patients with schizophrenia were reviewed as risk factors for diabetes.

RESULTS

People with schizophrenia show features of the metabolic syndrome at the onset of illness, before treatment. They also eat a poor diet, take little exercise and have high rates of smoking. Food intake may be increased further by antipsychotic medication. Nutritional factors appear to have a key role in the development of diabetes in patients with schizophrenia and may also affect the outcome and severity of schizophrenia. A common pathway through which diet might contribute to the development of both diabetes and schizophrenia is proposed.

CONCLUSIONS

Lifestyle factors may influence outcomes in both diabetes and schizophrenia. Lifestyle interventions are the key to improving the long-term health of people with schizophrenia.

Association of Ob-R gene polymorphism and insulin resistance in Japanese men

Leptin and its receptors are known to play a role in glucose metabolism. We succeeded in cloning human Ob-R cDNA and revealed 7 single nucleotide polymorphisms (SNPs) (Lys109Arg, Arg223Gln, Ser343Ser, Ser492Thr, Lys656Asn, Ala976Asp, and Pro1019Pro) in the coding region of Ob-Rb. Although these 7 SNPs were not associated with an obese phenotype, several studies have reported that some of them were associated with impaired glucose metabolism. To clarify whether the Arg223Gln and A3057G (Pro1019Pro) polymorphisms influence glucose metabolism in Japanese, 696 Japanese men were genotyped. Individually, the Arg223Gln and the A3057G polymorphisms were not associated with the glucose metabolic parameters. No associations were found between haplotype and clinical parameters. However, in 327 subjects with normal glucose tolerance (NGT), the subjects with Arg/Gln or Gln/Gln + A/A haplotype showed significantly higher serum insulin levels and homeostasis model assessment (HOMA) index than those with Arg/Arg + A/A haplotype and Arg/Gln or Gln/Gln + A/G or G/G haplotype. The subjects with Arg/Gln or Gln/Gln + A/A haplotype showed a significantly lower fasting glucose to insulin (GI) ratio than those with Arg/Arg + A/A haplotype. These results suggest that the Ob-R gene may serve as a modifier gene for insulin resistance in Japanese men.

The effect of a genetic variant for obesity and Type 2 Diabetes on the therapeutic potential of exercise and calorie restrictive diets in Zucker rats

Obesity and Type 2 Diabetes are modern pandemics caused by unique genetic-environmental interactions and distinguished by almost universal treatment failures. Relative influences of genome and lifestyle changes on an adult onset Obesity-Type 2 diabetes phenotype were explored. Zucker rats, a recessive model of genetic obesity-Type 2 Diabetes (117 fa/fa and 98 Fa/fa) were used. Dietary induced obesity (DIO) was imposed via a high fat diet on one-half; and one-half were forced to swim daily (EX). After 6 weeks, 78 animals were placed on a calorie (Kcal) restrictive diet for 6 more weeks. Genotype accounted for > 20% additional insulin resistance and obesity and modulated the effects of DIO and EX in adult animals exhibiting obesity-Type 2 diabetes. Only DIO gains were responsive to Kcal restriction. EX effects on insulin resistance were mediated by both Kcal restriction and genotype. Kcal restriction directly reduced hyperglycemia. Genetic variation was the major determinant of obesity and Type 2 Diabetes in Zucker rats. Genetically induced obesity and insulin sensitivity were resistant to EX and Kcal restriction; DIO and hyperglycemia were responsive to both. Successful treatment of Type 2 Diabetes requires understanding of how genotype may continue to modify adult responses to lifestyle change.

Human nutrition and food research: opportunities and challenges in the post-genomic era

Sequencing of the human genome has opened the door to the most exciting new era for nutritional science. It is now possible to study the underlying mechanisms for diet-health relationships, and in the near future dietary advice (and possibly tailored food products) for promoting optimal health could be provided on an individual basis, in relation to genotype and lifestyle. The role of food in human evolution is briefly reviewed, from palaeolithic times to modern-day hunter-gatherer societies. The aetiology of 'diseases of modern civilization', such as diabetes, heart disease and cancer, and the effect of changes in dietary patterns are discussed. The risk of disease is often associated with common single nucleotide polymorphisms, but the effect is dependent on dietary intake and nutritional status, and is often more apparent in intervention studies employing a metabolic challenge. To understand the link between diet and health, nutritional research must cover a broad range of areas, from molecular to whole body studies, and is an excellent example of integrative biology, requiring a systems biology approach. The annual cost to the National Health Service of diet-related diseases is estimated to be in excess of 15 billion, and although diet is a key component of any preventative strategy, it is not given the prominence it deserves. For example, less than 1% of the pound 1.6 billion budget for coronary heart disease is spent on prevention. The polygenic and multifactorial nature of chronic diseases requires substantial resources but the potential rewards, in terms of quality of life and economics, are enormous. It is timely therefore to consider investing in a long-term coordinated national programme for nutrition research, combining nutritional genomics with established approaches, to improve the health of individuals and of the nation.

Impaired coordination of nutrient intake and substrate oxidation in melanocortin-4 receptor knockout mice

Mutations in the melanocortin-4 receptor (MC4R) are associated with obesity. The obesity syndrome observed in humans with MC4R haploinsufficiency is similar to that observed in MC4R knockout mice, including increased longitudinal growth, hyperphagia, and fasting hyperinsulinemia. For comparison with other commonly investigated models of obesity and insulin resistance, we have backcrossed Mc4r-/- mice into the C57BL/6J (B6) background. Female obese Mc4r-/- mice exhibit reduced energy expenditure and an attenuated increase in fatty acid (FA) oxidation after exposure to high-fat diets compared with obese Lepob/Lepob mice. The reduced energy expenditure and FA oxidation correlates with changes in hepatic gene expression. The expression of genes involved in FA oxidation increased in obese Lepob/Lepob mice compared with wild-type and obese Mc4r-/- mice. In contrast, a key lipogenic enzyme, FA synthase (FAS), is increased in obese Mc4r-/- mice compared with obese Lepob/Lepob mice. Hyperinsulinemia, increased FAS mRNA expression and hepatic steatosis appear to be secondary to obesity in B6 Mc4r-/- mice. However, Mc4r-/- mice in a mixed genetic background develop severe hepatic steatosis at an early age. This might suggest an important role of the MC4R in regulating liver FA metabolism that is masked on the B6 background. Interestingly, the 10- to 20-fold increase in liver triglyceride in the outbred strain of Mc4r-/- mice is not always associated with fasting hyperinsulinemia or increased FAS mRNA expression. This observation suggests that changes in liver secondary to triglyceride accumulation lead to hyperinsulinemia and increased hepatic FAS expression in Mc4r-/- mice.

[Genetics of obesity and metabolic complications in the Quebec Family Study]

Considerable progress has been accomplished over the past 10 years in the understanding of the genetic basis of obesity and its related metabolic complications. It is now well established that obesity aggregates within families and that genes are partly responsible for this familial aggregation. The number of genes potentially involved in obesity continues to grow. This review summarizes the evidence accumulated so for regarding the contribution of genetic factors in obesity and the number of gene and loci linked to obesity in the Quebec Family Study.

Genome-wide linkage scan for the metabolic syndrome in the HERITAGE Family Study

The metabolic syndrome involves multiple and interactive effects of genes and environmental factors. To identify chromosomal regions encoding genes possibly predisposing to the metabolic syndrome, we performed a genome-wide scan with 456 white and 217 black participants from 204 nuclear families of the HERITAGE Family Study, using regression-based, single- and multipoint linkage analyses on 509 markers. A principal component analysis was performed on 7 metabolic syndrome-related phenotypes. Two principal components, PC1 and PC2 (55% of the variance), were used as metabolic syndrome phenotypes. ANOVA was used to quantify the familial aggregation of PC1 and PC2. Family membership contributed significantly (P < 0.0023) to the variance in PC1 (r(2) = 0.38 in whites; r(2) = 0.55 in blacks) and PC2 (r(2) = 0.51; r(2) = 0.48). In whites, promising evidence for linkage (P < 0.0023) was found for PC1 (2 markers on 10p11.2) and PC2 (a marker on 19q13.4). Suggestive evidence of linkage (0.01 > P > 0.0023) appeared for PC1 (1q41 and 9p13.1) and PC2 (2p22.3). In blacks, promising linkage was found for PC2 on 1p34.1, and suggestive linkage was found on 7q31.3 and 9q21.1. The genome-wide scan revealed evidence for quantitative trait loci on chromosomal regions that have been previously linked with individual cardiovascular disease and type 2 diabetes risk factors. Some of these chromosomal regions harbor promising potential candidate genes.

Preproghrelin Leu72Met polymorphism in patients with type 2 diabetes mellitus

OBJECTIVES

The association between the Leu72Met polymorphism of the preproghrelin gene and diabetic complications was examined in patients with type 2 diabetes mellitus.

SUBJECTS AND METHODS

A total of 258 patients with type 2 diabetes mellitus and 522 control subjects were screened. Genotypes were determined by polymerase chain reaction technique. The diagnosis of coronary heart disease was based on clinical and ECG criteria. Laboratory analyses were carried out in the hospital laboratory.

RESULTS

No differences in the genotype distributions and allele frequencies of the preproghrelin Leu72Met polymorphism were found between type 2 diabetes mellitus patients and controls. The polymorphism was not associated with macro- or micro-angiopathy or hypertension. However, Leu72Met polymorphism was associated with serum creatinine (P = 0.006) and lipoprotein(a) [Lp(a)] levels (P = 0.006) with Leu72Leu subjects showing the highest values. This association was observed only amongst diabetic group.

CONCLUSIONS

The Leu72Met polymorphism of the preproghrelin gene was not related to cardiovascular disease in type 2 diabetes mellitus patients. Leu72Met polymorphism was, however, associated with serum creatinine and Lp(a) levels in diabetic patients. The mechanism might be associated with a possible change in ghrelin product and its somatotropic effect.

Minimal model-based insulin sensitivity has greater heritability and a different genetic basis than homeostasis model assessment or fasting insulin

Insulin resistance is an important risk factor for development of type 2 diabetes as well as other chronic conditions, including hypertension, cardiovascular disease, and colon cancer. To find genes for insulin resistance it is necessary to assess insulin action in large populations. We have previously measured insulin action in a large cohort of subjects (Insulin Resistance and Atherosclerosis Study [IRAS] Family Study) using the minimal model approach. In this study, we compare sensitivity from the minimal model (insulin sensitivity index [S(I)]) with the measure of insulin resistance emanating from the homeostasis model assessment (HOMA) approach. The former measure emerges from the glycemic response to endogenous and exogenous insulin; the latter is based solely on fasting measures of glucose and insulin. A total of 112 pedigrees were represented, including 1,362 individuals with full phenotypic assessment. Heritability of S(I) was significantly greater than that for HOMA (0.310 vs. 0.163) and for fasting insulin (0.171), adjusted for age, sex, ethnicity, and BMI. In addition, correlation between S(I) and either HOMA or fasting insulin was only approximately 50% accounted for by genetic factors, with the remainder accounted for by environment. Thus S(I), a direct measure of insulin sensitivity, is determined more by genetic factors rather than measures such as HOMA, which reflect fasting insulin.

Common gene polymorphisms and nutrition: emerging links with pathogenesis of multifactorial chronic diseases (review)

Rapid progress in human genome decoding has accelerated search for the role of gene polymorphisms in the pathogenesis of complex multifactorial diseases. This review summarizes the results of recent studies on the associations of common gene variants with multifactorial chronic conditions strongly affected by nutritional factors. Three main individual sections discuss genes related to energy homeostasis regulation and obesity, cardiovascular disease (CVD), and cancer. It is evident that several major chronic diseases are closely related (often through obesity) to deregulation of energy homeostasis. Multiple polymorphic genes encoding central and peripheral determinants of energy intake and expenditure have been revealed over the past decade. Food intake control may be affected by polymorphisms in the genes encoding taste receptors and a number of peripheral signaling peptides such as insulin, leptin, ghrelin, cholecystokinin, and corresponding receptors. Polymorphic central regulators of energy intake include hypothalamic neuropeptide Y, agouti-related protein, melanocortin pathway factors, CART (cocaine- and amphetamine-regulated transcript), some other neuropeptides, and receptors for these molecules. Potentially important polymorphisms in the genes encoding energy expenditure modulators (alpha- and beta- adrenoceptors, uncoupling proteins, and regulators of adipocyte growth and differentiation) are also discussed. CVD-related gene polymorphisms comprising those involved in the pathogenesis of atherosclerosis, blood pressure regulation, hemostasis control, and homocysteine metabolism are considered in a separate section with emphasis on multiple polymorphisms affecting lipid transport and metabolism and their interactions with diet. Cancer-associated polymorphisms are discussed for groups of genes encoding enzymes of xenobiotic metabolism, DNA repair enzymes, factors involved in the cell cycle control, hormonal regulation-associated proteins, enzymes related to DNA methylation through folate metabolism, and angiogenesis-related factors. There is an apparent progress in the field with hundreds of new gene polymorphisms discovered and characterized, however firm evidence consistently linking them with pathogenesis of complex chronic diseases is still limited. Ways of improving the efficiency of candidate gene approach-based studies are discussed in a short separate section. Successful unraveling of interaction between dietary factors, polymorphisms, and pathogenesis of several multifactorial diseases is exemplified by studies of folate metabolism in relation to CVD and cancer. It appears that several new directions emerge as targets of research on the role of genetic variation in relation to diet and complex chronic diseases. Regulation of energy homeostasis is a fundamental problem insufficiently investigated in this context so far. Impacts of genetic variation on systems controlling angiogenesis, inflammatory reactions, and cell growth and differentiation (comprising regulation of the cell cycle, DNA repair, and DNA methylation) are also largely unknown and need thorough analysis. These goals can be achieved by complex simultaneous analysis of multiple polymorphic genes controlling carefully defined and selected elements of relevant metabolic and regulatory pathways in meticulously designed large-scale studies.

Diet-dependent obesity and hypercholesterolemia in the New Zealand obese mouse: identification of a quantitative trait locus for elevated serum cholesterol on the distal mouse chromosome 5

AIMS

New Zealand obese (NZO) mice exhibit a polygenic syndrome of obesity, insulin resistance, and hypercholesterolemia that resembles the human metabolic syndrome. This study was performed in order to locate genes responsible for elevated serum cholesterol and to compare their effects under a standard and high fat diet.

METHODS

A backcross population of NZO with SJL mice (NZO x F1(SJL x NZO)) was generated. Mice were raised on a normal or high fat diet and were monitored for 22 weeks (body weight, serum cholesterol, and blood glucose). A genome-wide scan was performed by genotyping of approximately 200 polymorphic microsatellite markers by PCR and linkage analysis was performed with the MAPMAKER program.

RESULTS

In the genome-wide scan, a single susceptibility locus for hypercholesterolemia (Chol1/NZO, maximum LOD score 14.5 in a combined population of 523 backcross mice) was identified on chromosome 5. Cholesterol levels were significantly elevated in both male and female homozygous carriers of the Chol1/NZO allele. The locus maps 40cM distal of the previously described obesity locus Nob1 in the vicinity of the marker D5Mit244 and in the vicinity of hypercholesterolemia QTL previously identified in the NZB, CAST, and C57BL/6J strains. Chol1/NZO was not associated with elevated body weight, serum insulin, or hyperglycemia. The high fat diet significantly increased serum cholesterol levels, but the fat content of the diet did not alter the absolute effect of Chol1/NZO.

CONCLUSIONS

Chol1/NZO is a major susceptibility locus on the distal mouse chromosome 5, which produces gender-independent hypercholesterolemia in NZO mice. The effect of Chol1/NZO was independent of the dietary fat content and was not associated with the other traits of the metabolic syndrome. Thus, it is suggested that the responsible gene might be involved in cholesterol metabolism.

The effect of fiber-rich carbohydrates on features of Syndrome X

There has been much debate among nutritionists and scientists regarding the optimal dietary approach for the treatment of the Insulin Resistance Syndrome, also called Syndrome X. This condition, which may affect as many as 47 million individuals in the United States, significantly increases risk of coronary heart disease and stroke. Major health organizations have historically recommended high-carbohydrate, low-fat (HCLF) diets to reduce chronic disease risk. However, there is evidence that a high intake of carbohydrates may adversely affect one or more of the abnormalities associated with this syndrome. Studies in this area have often had limitations. For example, some studies showing adverse effects of an HCLF diet have not taken into account the dietary fiber content of the diet. This article describes abnormalities often associated with Syndrome X, reviews the beneficial effects of fiber-rich carbohydrates, discusses the effect of fiber-rich carbohydrates on features of this syndrome, and concludes with applications of these findings for those involved in treating individuals with features of this disorder. This review indicates that an HCLF dietary pattern such as that used in the DASH trial, with a level of dietary fiber consistent with the recommendations of the American Dietetic Association (eg, 20-35g/day), containing from 3 to 10 g soluble fiber/day, may be beneficial for treating those with Syndrome X.

Waging war on physical inactivity: using modern molecular ammunition against an ancient enemy

A hypothesis is presented based on a coalescence of anthropological estimations of Homo sapiens' phenotypes in the Late Paleolithic era 10,000 years ago, with Darwinian natural selection synergized with Neel's idea of the so-called thrifty gene. It is proposed that humans inherited genes that were evolved to support a physically active lifestyle. It is further postulated that physical inactivity in sedentary societies directly contributes to multiple chronic health disorders. Therefore, it is imperative to identify the underlying genetic and cellular/biochemical bases of why sedentary living produces chronic health conditions. This will allow society to improve its ability to effect beneficial lifestyle changes and hence improve the overall quality of living. To win the war against physical inactivity and the myriad of chronic health conditions produced because of physical inactivity, a multifactorial approach is needed, which includes successful preventive medicine, drug development, optimal target selection, and efficacious clinical therapy. All of these approaches require a thorough understanding of fundamental biology and how the dysregulated molecular circuitry caused by physical inactivity produces clinically overt disease. The purpose of this review is to summarize the vast armamentarium at our disposal in the form of the extensive scientific basis underlying how physical inactivity affects at least 20 of the most deadly chronic disorders. We hope that this information will provide readers with a starting point for developing additional strategies of their own in the ongoing war against inactivity-induced chronic health conditions.

Cholesterol gallstone formation in overweight mice establishes that obesity per se is not linked directly to cholelithiasis risk

The relationship between obesity and cholesterol cholelithiasis is not well understood at physiologic or genetic levels. To clarify whether obesity per se leads to increased prevalence of cholelithiasis, we examined cholesterol gallstone susceptibility in three polygenic (KK/H1J, NON/LtJ, NOD/LtJ) and five monogenic [carboxypeptidase E (Cpe (fat)), agouti yellow (A(y)), tubby (tub), leptin (Lep(ob)), leptin receptor (Lepr (db))] murine models of obesity during ingestion of a lithogenic diet containing dairy fat, cholesterol, and cholic acid. At 8 weeks on the diet, one strain of polygenic obese mice was resistant whereas the others revealed low or intermediate prevalence rates of cholelithiasis. Monogenic obese mice showed distinct patterns with either high or low gallstone prevalence rates depending upon the mutation. Dysfunction of the leptin axis, as evidenced by the Lep(ob) and the Lepr (db) mutations, markedly reduced gallstone formation in a genetically susceptible background strain, indicating that in mice with this genetic background, physiologic leptin homeostasis is a requisite for cholesterol cholelithogenesis. In contrast, the Cpe (fat) mutation enhanced the prevalence of cholelithiasis markedly when compared with the background strain. Since CPE converts many prohormones to hormones, a deficiency of biologically active cholecystokinin is a likely contributor to enhanced susceptibility to cholelithiasis through compromising gallbladder contractility and small intestinal motility. Because some murine models of obesity increased, whereas others decreased cholesterol gallstone susceptibility, we establish that cholesterol cholelithiasis in mice is not simply a secondary consequence of obesity per se. Rather, specific genes and distinct pathophysiological pathways are responsible for the shared susceptibility to both of these common diseases.

Genetics of eating and its relation to obesity

Humans show remarkable variability in their eating styles. Reasons for this variability are poorly understood, but carry important implications for the onset of obesity and its comorbidities. Although it is well established that genes influence obesity, genetic influences on human eating patterns have received less attention. Dramatic increases in the prevalence of obesity justify additional research into the genetics of eating style. This review highlights what is known about the genetics of food preferences and selection in humans. Data from family and twin studies suggest a moderate genetic contribution to eating style, with clear environmental effects emerging as well. Select studies show support for gene-environment interactions and common genetic bases for certain dietary patterns, obesity, and/or metabolic complications. Genetically informative designs that infuse innovative behavioral measures may help explain individual differences in eating styles and hopefully promote more effective obesity treatments.

Metabolic syndrome and aging in Wistar Ottawa Karlsburg W rats

BACKGROUND AND OBJECTIVE

Comparative studies have shown that Wistar Ottawa Karlsburg W (RT1u) rats (WOKW) develop a nearly complete metabolic syndrome with obesity, moderate hypertension, dyslipidemia, hyperinsulinemia, and impaired glucose tolerance up to an age of 28 weeks. Because metabolic data thereafter are missing, WOKW and disease-resistant DA rats were studied for 12 months beginning at an age of 5 months.

METHODS

Eighteen male inbred WOKW and DA rats were studied monthly from the 5th to the 17th month of life for traits of the metabolic syndrome such as body weight, body mass index (BMI), serum triglycerides, total cholesterol, leptin, insulin as well as glucose tolerance, 24 h excretion of urine total protein and creatinine including telemetric measurement of blood pressure in six males per each group.

RESULTS

Except for serum total cholesterol, the measured values for most traits studied were significantly higher in WOKW than in DA rats at an age of 5 months. At an age of 17 months all traits were significantly elevated in WOKW compared with DA rats. WOKW rats were hypertensive, dyslipidemic, obese, glucose intolerant, hyperinsulinemic and proteinuric.

CONCLUSION

Considering the phenotype of the WOKW rat described until now and the fact that the metabolic syndrome in this rat is polygenetically determined, the WOKW rat is the most suitable animal model to study the pathophysiology of the facets of the syndrome.