Physiological stress responses in defensive individuals: Age and sex matter

The association between defensiveness and physiological responses to stress were evaluated in 81 healthy working men and 118 women, aged 20 to 64 years (M=41; SD=11.45). Participants underwent laboratory testing during which they were exposed to interpersonal stressors. Heart rate (HR), heart rate variability (HRV), blood pressure (BP), and salivary cortisol were measured. Defensiveness was evaluated using the Marlowe‐Crowne Social Desirability Scale. In women, higher defensiveness was associated with greater BP and HR reactivity to stress (p<.05). In older men, lower defensiveness was associated with increased systolic BP reactivity to stress (p<.02), delayed HRV recovery (p<.02), and greater salivary cortisol levels (p<.02). In conclusion, greater defensiveness was associated with increased reactivity to stress in women whereas in older men, lower defensiveness was associated with elevated cardiovascular, autonomic, and endocrine responses to stress.     

MTTP variants and body mass index, waist circumference and serum cholesterol level: Association analyses in 7582 participants of the KORA study cohort

The microsomal triglyceride transfer protein (MTTP) is a key regulator in the assembly and secretion of chylomicrons and very low density lipoprotein (VLDL) in the intestine and in liver. Associations between MTTP variants and traits of the metabolic syndrome are carried out in relatively small cohorts and are not consistent.We analysed MTTP polymorphisms in 7582 participants of the KORA study cohort. Seven htSNPs covering a 52 kb region of the MTTP locus and two cSNPs (I128T, H297Q) were selected.A MTTP haplotype containing the minor allele of H297Q showed a significant decrease of −0.636 (95% CI: −1.226, −0.046; p = 0.035) BMI units in females but not in males. In comparison to homozygous H-carriers for the major allele of the MTTP H297Q polymorphism, homozygous Q297Q carriers showed a significant decrease in BMI of −0.425 BMI units (95% CI: −0.74, −0.12; p = 0.007), in waist circumference of −0.990 cm (95% CI: 1.74, −0.24; p = 0.01) and in total cholesterol of −0.039 mmol/l (95% CI: −0.07, 0; p = 0.03). Heterozygous Q-carriers displayed a reduction in BMI of −0.183 BMI unit (95% CI: −0.33, −0.04; p = 0.012), in waist circumference of −0.45 cm (95% CI: 0.8, −0.1; p = 0.01) and in total cholesterol of −0.103 mmol/l (95% CI: −0.18, −0.03; p = 0.01). Gender stratified statistics revealed a significant reduction of −0.657 BMI units (95% CI: −1.14, −0.18; p = 0.007), −1.437 cm waist circumference (95% CI: −2.55, −0.32; p = 0.01) and −0.052 mmol/l total cholesterol (95% CI: −0.1, −0.01; p = 0.03) for females homozygous for the Q297Q polymorphism. Females carrying the Q-allele showed a decrease of −0.259 BMI unit (95% CI: −0.48, −0.04; p = 0.023), −0.662 cm waist circumference (95% CI: −1.18, −0.14; p = 0.01) and −0.111 mmol/l total cholesterol (95% CI: −0.21, −0.01; p = 0.03).Our association analysis in a large population based study cohort provides evidence that the minor allele of the MTTP H297Q polymorphism is associated with lower BMI, waist circumference and total cholesterol in females but not in males.     

Is neck circumference measurement an indicator for abdominal obesity? A pilot study on Turkish Adults

Background

Neck circumference (NC) measurement is one of the simple screening measurements which can be used as an index of upper body fat distribution to identify obesity.

Objectives

The aim of this study was to determine the relationship between neck circumferences and obesity.

Methods

A total 411 volunteer adults participated in this study (174 men, 237 women). A questionnaire which consisted of anthropometric measurements and demographic features was used. Patients with NC ≥37 cm for men and ≥34 cm for women require evaluation of overweight status.

Results

The percentages of the men and women with BMI ≥ 25kg/m² were 55.2% and 27.0% respectively and with high neck circumferences were 85.1% and 38.8%, respectively. The percentages of the men and women with high waist circumference were 31.6% and 79.3%, respectively. In both gender there were positive significant correlations between neck circumference, body weight (men, r=0.576; women, r=0.702; p=0.000), waist circumferences (men, r=0.593; women r=0.667; p=0.000), hip circumferences (men, r=0.568; women, r=0.617; p=0.000) and BMI (men, r=0.587; women, r=0.688; p=0.000).

Conclusions

This study indicates that NC was associated with body weight, BMI, waist and hip circumferences and waist/hip ratio for men and women. A significant association was found between NC and conventional overweight and obesity indexes. NC was associated with waist/hip ratio for men and women.     

Sex-specific effect of aging on submaximal leg exercise hemodynamics in middle-aged and older adults

The purpose of the study was to examine predictors of the leg hemodynamic response to exercise in middle- and older-aged men and women. Femoral artery blood flow (FBF), mean arterial pressure (MAP), and femoral vascular conductance (FVC, calculated as the quotient of FBF and MAP) were measured at rest and during 5 min of single knee-extensor exercise at ~10 W workload in healthy men (n = 31) and women (n = 32) (age 40–72 years). Age, menopausal status, maximal quadriceps strength, blood lipids, vitamin D levels, maximal oxygen uptake (VO_2max), physical activity, blood pressure, estimated quadriceps muscle mass, and body mass index (BMI) were also assessed. The effect of age on FBF and FVC was negative and significant in men (r = −0.44 and −0.42 and p = 0.01 and 0.02, respectively) but was abolished by normalization to estimated quadriceps muscle (p = 0.18 and 0.73, respectively). There was no effect of age on leg hemodynamic responses to exercise in women (alone or normalized to quadriceps muscle), but menopausal status was a significant predictor of FVC and normalized FVC (p = 0.04 and 0.02, respectively). The multivariate model for exercising FVC in men (in order of strongest to weakest predictors) included quadriceps strength, BMI, resting FVC, age, and high-density lipoprotein cholesterol. The multivariate model for exercising FVC in women included quadriceps mass, systolic blood pressure, vitamin D, age, VO_2max, waist circumference, and physical activity score. These findings suggest that factors besides chronological age mediate exercising leg hemodynamics in middle-aged to older adults and that these factors are sex-specific.     

Influence of metabolic syndrome and its components on subclinical organ damage in hypertensive perimenopausal women

PurposeWe investigated the association between metabolic syndrome (MS), its components and the presence of subclinical organ damage in hypertensive perimenopausal women.Patients/methods152 women with newly diagnosed, untreated arterial hypertension (mean age 51.0 ± 3.5 years) were included in the study. In all subjects anthropometrical measurements, 24-hr blood pressure monitoring, echocardiographic examination, and carotid ultrasound were performed. Carotid-femoral pulse wave velocity (PWV) was measured to obtain data on vascular compliance. As the index of early kidney damage both glomerular filtration rate was calculated and albumin/creatinine ratio in the urine sample was measured. A fasting blood sample was taken to measure glucose and lipid concentration.ResultsMS was found in 41% of patients. Patients with MS exhibited elevated left ventricular mass index (LVMI 84.7 vs. 78.8 g/m^2.7, p = 0.03), higher intima-media thickness (IMT 0.67 vs. 0.62 mm, p = 0.003), greater prevalence of LV hypertrophy (30% vs. 13%, p = 0.01), and carotid plaques (24% vs. 15%, p = 0.01). The multivariate regression analysis revealed that components of MS (systolic blood pressure and waist circumference) are stronger predictors of LVM than MS itself. The relationship between MS and LVMI lost its significance when BMI was included in the model, and remained significant for IMT.ConclusionIn hypertensive perimenopausal women components of MS are stronger predictors of subclinical organ damage than MS itself. Left ventricular mass and hypertrophy are more strongly correlated with increasing body weight than with the presence of MS. MS, independently of BMI, influences the level of subclinical atherosclerosis in the study group.     

Waist circumference and serum adiponectin levels in obese and non-obese postmenopausal women

Objectives

A proposed missing link between obesity and metabolic disturbances is adiponectin, an adipocyte-derived peptide. Adiponectin is a potent antidiabetic hormone and seems to have a beneficial influence on lipid profile as well. The need to explain the complex physiological roles of this hormone prompted the authors to study the relationship between adiponectin level and obesity – related abnormalities in a homogenous population of postmenopausal women.

Study design

The study involved 272 postmenopausal women aged 50–60 years. Invitations to participate in the study were sent to 4000 randomly chosen women from the Wroclaw city population fulfilling the age criterion. A telephone questionnaire was administered to the group of 1731 women who responded to the invitation and then subjects for the study were selected. Main outcome measures anthropometrical measurements of body fat tissue content and fat tissue distribution assessment were carried out in all the women. Moreover, serum concentrations of adiponectin, glucose, total cholesterol, HDL cholesterol, triglycerides and insulin were measured.

Results

The most frequent (76%) phenotype among the investigated women was obesity (BMI >25) with abnormal (= 80 cm) waist circumference (OAW), Obesity with normal (<80 cm) waist (ONW) and normal weight with abnormal waist (NOAW) were observed in only 5% and 14% of the women, respectively. Non-obese women with normal waist (NONW) were noted in only 5% of the subjects. Serum adiponectin levels in both groups of non-obese women (NOAW and NONW) were significantly higher (p < 0.05) than in the women with obesity or overweight and abnormal waist circumference (OAW group). Adiponectin levels in the women with obesity or overweight and normal waist (ONW) were also higher than in the OAW group; however, this difference was not statistically significant (p = 0.05). In all the women, serum adiponectin level correlated negatively with BMI (r = −0.34, p = 0.0001), total fat (r = −0.28, p = 0.0001), android fat deposit (r = −0.23, p = 0.0001), waist circumference (r = −0.33, p = 0.0001), glucose (r = −0.27, p = 0.0001), triglycerides (r = −0.34, p = 0.0001), and FIRI (r = −0.34, p = 0.0001) and positively with the gynoid/android fat deposit ratio (r = 0.28, p = 0.0001) and HDL cholesterol (r = 0.36, p = 0.0001).

Conclusions

These results confirm that adiponectin could be a marker of the development of menopausal insulin resistance syndrome.     

Gender‐specific anthropometric markers of adiposity,metabolic syndrome and visceral adiposity index (VAI) in patients with obstructive sleep apnea

Obstructive sleep apnea often coexists with visceral adiposity and metabolic syndrome. In this study, we analysed gender‐related differences in anthropometrics according to sleep apnea severity and metabolic abnormalities. In addition, the visceral adiposity index, a recently introduced marker of cardiometabolic risk, was analysed. Consecutive subjects with suspected obstructive sleep apnea (n = 528, 423 males, mean age ± standard deviation: 51.3 ± 12.8 years, body mass index: 31.0 ± 6.2 kg m^?2) were studied by full polysomnography (apnea–hypopnea index 43.4 ± 27.6 h^?1). Variables of general and visceral adiposity were measured (body mass index, neck, waist and hip circumferences, waist‐to‐hip ratio). The visceral adiposity index was calculated, and metabolic syndrome was assessed (NCEP‐ATP III criteria). The sample included controls (apnea–hypopnea index <10 h^?1, n = 55), and patients with mild–moderate (apnea–hypopnea index 10–30 h^?1, n = 144) and severe sleep apnea (apnea–hypopnea index >30 h^?1, n = 329). When anthropometric variables were entered in stepwise multiple regression, body mass index, waist circumference and diagnosis of metabolic syndrome were associated with the apnea–hypopnea index in men (adjusted R² = 0.308); by contrast, only hip circumference and height‐normalized neck circumference were associated with sleep apnea severity in women (adjusted R² = 0.339). These results changed little in patients without metabolic syndrome; conversely, waist circumference was the only correlate of apnea–hypopnea index in men and women with metabolic syndrome. The visceral adiposity index increased with insulin resistance, but did not predict sleep apnea severity. These data suggest gender‐related interactions between obstructive sleep apnea, obesity and metabolic abnormalities. The visceral adiposity index was a good marker of metabolic syndrome, but not of obstructive sleep apnea.     

Gender differences in clinical,laboratory and polysomnographic features of restless legs syndrome

Restless legs syndrome is a common neurological disorder with a clear female predominance. This study aims to evaluate gender differences in clinical, laboratory and polysomnographic features in patients with restless legs syndrome. For this retrospective analysis, 42 women and 42 men from the Innsbruck RLS database matched by age and therapy were included. Demographic data as well as different severity scales (IRLS, RLS‐6 and CGI) were evaluated. Laboratory parameters included several indicators of serum iron status. In all patients, polysomnography was performed according to the AASM guidelines, and periodic leg movements during sleep were scored according to the AASM criteria. IRLS, RLS‐6 and CGI revealed more severe symptoms in women (IRLS median [range]: 17.5 [0–35] versus 13.5 [0–32], p = 0.028; RLS‐6 median [range]: 18 [0–39] versus 12 [1–42], p = 0.014). Women had lower serum ferritin levels than men (median [range] in μg L^?1: 74 [9–346] versus 167 [15–389], p < 0.001). Twenty‐two women and eight men (53.7% versus 22.2%, p = 0.003) had ferritin values below 75 μg L^?1. Periodic leg movements during sleep indices were significantly lower in women than in men (median [range] in number per hr: 11.4 [0–62.5] versus 40 [0–154], p = 0.004, and 12.6 [0–58.5] versus 40 [0.5–208], p = 0.002, for night I and night II, respectively). Restless legs syndrome severity as measured by validated scales was worse in women, while periodic leg movements during sleep indices were higher in men. These results suggest a possible gender difference in phenotypical presentation of restless legs syndrome, manifesting with predominantly sensory symptoms in women and predominantly motor symptoms in men.     

GAD2 gene sequence variations are associated with eating behaviors and weight gain in women from the Quebec family study

The glutamate decarboxylase 2 (GAD2) gene encodes for the glutamic acid decarboxylase enzyme (GAD65), which is implicated in the formation of the γ-aminobutyric acid (GABA), a neurotransmitter involved in the regulation of food intake. The objective of the present study was to test for association between GAD2 single-nucleotide polymorphisms (SNPs) and eating behaviors, dietary intake and obesity in subjects (n = 873) from the Quebec Family Study (QFS). Energy and macronutrient intakes were measured using a 3-day dietary record and eating behaviors were assessed using the Three-Factor Eating Questionnaire (TFEQ). Six SNPs capturing about 90% of GAD2 gene variability were genotyped and tested for association with age- and BMI- adjusted phenotypes. No evidence of association was found in men. In women, a SNP (rs992990; c.61450 C > A) was associated with disinhibition (p = 0.028), emotional susceptibility to disinhibition (p = 0.0005) and susceptibility to hunger (p = 0.028). Another SNP (rs7908975; c.8473A > C) was associated with carbohydrate (p = 0.021) and lipid (p = 0.021) intakes, disinhibition (p = 0.011) and two of its subscales (emotional and situational susceptibility) as well as with avoidance of fattening foods (p = 0.036). Six-year weight gain was two times higher in women carrying the variants associated with eating behaviors: 4.2 kg (vs 2.1 kg in non-carriers) in A-allele carriers of c.61450 C > A (p = 0.038) and 4.9 kg (vs 2.5 kg in non-carriers) in C-allele carriers of c. 8473 A > C (p = 0.013). The results suggest a role for the GAD2 gene in determining food intake, eating behaviors and weight gain over time in women.     

Genetic effects of adiponectin single nucleotide polymorphisms on the clustering of metabolic risk factors in young Korean adults

Little is known if lifestyle-related risk factors modulate the adiponectin genetic effects on its outcome phenotypes. The aims of the study were to investigate whether the association between the adiponectin gene two SNPs (+45T>G, rs2241766 and +276G>T, rs1501299) and a clustering of metabolic risk factors is modified by both cardiorespiratory fitness (CRF) and insulin resistance in a study sample of 1,622 young Korean adults (941 men and 681 women, mean age 22.9 ± 2.4 years). The clustering of metabolic risk factors was defined as a sum of Z scores for waist circumference (WC), blood pressure (BP), triacylglycerols (TAG), high-density lipoprotein cholesterol, and fasting glucose. With respect to SNP +45T>G, the TT genotype had significantly higher values for BMI, WC, systolic BP, TAG, insulin, and a clustered risk score than did the TG+GG genotype. The genetic effect of SNP +45 on the clustered risk score remained significant even after controlling for age, sex, and smoking (P = 0.019). However, the genetic impact was no longer significant when additionally controlling for CRF (P = 0.097) and fasting insulin (P = 0.181), respectively. With respect to SNP +276G>T, the GT+TT genotypes had significantly higher values for BMI and TAG than did the TT genotype. In summary, the present findings suggest that the SNPs at position +45 and +276 are associated with several of metabolic risk factors; however, the genetic effect of SNP +45T/G variant on the clustered risk score is modulated by both CRF and insulin resistance.     

Longitudinal relationship between physical activity and cardiometabolic factors in overweight and obese adults

Few studies have reported longitudinal relationships between physical activity (PA) and cardiometabolic risk factors over time using repeated assessments in overweight or obese adults. We conducted a longitudinal study in 127 participants (81% with body mass index > 30 kg/m²) who completed a 12-month behavioral intervention for weight loss between 2003 and 2005 in Pittsburgh, PA, USA. Using absolute change scores from baseline to each time point (i.e., 6 and 12 months) for all studied variables (Δ = time point − baseline), we performed mixed effects modeling to examine relationships between PA and cardiometabolic risk factors, after adjusting for body weight, energy intake and other covariates (i.e., age, gender, and ethnicity). PA was assessed as energy expenditure (kcal/week) using the Paffenbarger activity questionnaire. Over the 12-month period, energy expenditure increased (Δ1,370 kcal/week at 6 months vs. Δ886 kcal/week at 12 months); body weight decreased (Δ8.9 kg at 6 months vs. Δ8.4 kg at 12 months). The average increase in energy expenditure over 12 months was significantly and independently related to reductions in total cholesterol (F = 6.25, p = 0.013), low-density lipoprotein cholesterol (LDL-C) (F = 5.08, p = 0.025) and fasting blood glucose (F = 5.10, p = 0.025), but not to other risk factors (i.e., fasting insulin, high-density lipoprotein cholesterol, triglycerides, and waist circumference). In conclusion, among overweight and obese adults undergoing a weight loss intervention, increased energy expenditure over 12 months may improve total cholesterol and LDL-C, important coronary risk factors, and fasting blood glucose, a metabolic risk factor.     

Brain glucose and acetoacetate metabolism: a comparison of young and older adults

The extent to which the age-related decline in regional brain glucose uptake also applies to other important brain fuels is presently unknown. Ketones are the brain's major alternative fuel to glucose, so we developed a dual tracer positron emission tomography protocol to quantify and compare regional cerebral metabolic rates for glucose and the ketone, acetoacetate. Twenty healthy young adults (mean age, 26 years) and 24 healthy older adults (mean age, 74 years) were studied. In comparison with younger adults, older adults had 8 ± 6% (mean ± SD) lower cerebral metabolic rates for glucose in gray matter as a whole (p = 0.035), specifically in several frontal, temporal, and subcortical regions, as well as in the cingulate and insula (p ≤ 0.01, false discovery rate correction). The effect of age on cerebral metabolic rates for acetoacetate in gray matter did not reach significance (p = 0.11). Rate constants (min⁻¹) of glucose (Kg) and acetoacetate (Ka) were significantly lower (−11 ± 6%; [p = 0.005], and −19 ± 5%; [p = 0.006], respectively) in older adults compared with younger adults. There were differential effects of age on Kg and Ka as seen by significant interaction effects in the caudate (p = 0.030) and post-central gyrus (p = 0.023). The acetoacetate index, which expresses the scaled residuals of the voxel-wise linear regression of glucose on ketone uptake, identifies regions taking up higher or lower amounts of acetoacetate relative to glucose. The acetoacetate index was higher in the caudate of young adults when compared with older adults (p ≤ 0.05 false discovery rate correction). This study provides new information about glucose and ketone metabolism in the human brain and a comparison of the extent to which their regional use changes during normal aging.     

A cross-sectional study of sarcopenia in Japanese men and women: reference values and association with cardiovascular risk factors

In this study of Japanese men and women, we determine reference values for sarcopenia and test the hypothesis that sarcopenia is associated with risk factors for cardiovascular disease, independent of waist circumference. A total of 1,488 Japanese men and women aged 18–85 years participated in this study. Appendicular muscle mass (AMM) was measured by dual-energy X-ray absorptiometry. Reference values for classes 1 and 2 sarcopenia (skeletal muscle index: AMM/height², kg m⁻²) in each sex were defined as values one and two standard deviations below the sex-specific means of reference values obtained in this study from young adults aged 18–40 years. The reference values for class 1 and class 2 sarcopenia were 7.77 and 6.87 kg m⁻² in men and 6.12 and 5.46 kg m⁻² in women. In subjects both with class 1 and class 2 sarcopenia, body mass index and % body fat were significantly lower than in normal subjects. Despite whole-blood glycohaemoglobin A1c in men with class 1 sarcopenia was significantly higher than in normal subjects, and brachial-ankle pulse wave velocity in women both with class 1 and class 2 sarcopenia were significantly higher than in normal subjects, using one-way ANCOVA with adjustment for the covariate of waist circumference. Although sarcopenia is associated with thin body mass, it is associated with more glycation of serum proteins in men and with greater arterial stiffness in women, independent of waist circumference.     

Architectural anatomy of the quadriceps and the relationship with muscle strength: An observational study utilising real-time ultrasound in healthy adults

Quadriceps atrophy and morphological change is a known phenomenon that can impact significantly on strength and functional performance in patients with acute or chronic presentations conditions. Real-time ultrasound (RTUS) imaging is a noninvasive valid and reliable method of quantifying quadriceps muscle anatomy and architecture. To date, there is a paucity of normative data on the architectural properties of superficial and deep components of the quadriceps muscle group to inform assessment and evaluation of intervention programs. The aims of this study were to (1) quantify the anatomical architectural properties of the quadriceps muscle group (rectus femoris, vastus intermedius, and vastus lateralis) using RTUS in healthy older adults and (2) to determine the relationship between RTUS muscle parameters and measures of quadriceps muscle strength. Thirty middle aged to older males and females (age range 55–79 years; mean age =59.9 ± 7.08 years) were recruited. Quadriceps muscle thickness, cross-sectional area, pennation angle, and echogenicity were measured using RTUS. Quadriceps strength was measured using hand-held dynamometry. For the RTUS-derived quadriceps morphological data, rectus femoris mean results; circumference 9.3 cm; CSA 4.6 cm²; thickness 1.5 cm; echogenicity 100.2 pixels. Vastus intermedius mean results; thickness 1.8 cm; echogenicity 99.1 pixels. Vastus lateralis thickness 1.9 cm; pennation angle 17.3 ° ; fascicle length 7.0 cm. Quadriceps force was significantly correlated only with rectus femoris circumference (r = 0.48, p = 0.007), RF echogenicity (r = 0.38, p = 0.037), VI echogenicity (r = 0.43, p = 0.018), and VL fascicle length (r = 0.43, p = 0.019). Quadriceps force was best predicted by a three-variable model (adjusted R² = 0.46, p < 0.001) which included rectus femoris echogenicity (B = 0.43, p = 0.005), vastus lateralis fascicle length (B = 0.33, p = 0.025) and rectus femoris circumference (B = 0.31, p = 0.041). Thus respectively, rectus femoris echogenicity explains 43%, vastus lateralis fascicle length explains 33% and rectus femoris circumference explains 31% of the variance of quadriceps force. The study findings suggest that RTUS measures were reliable and further research is warranted to establish whether these could be used as surrogate measures for quadriceps strength in adults to inform exercise and rehabilitation programs.     

Circulating visfatin level and visfatin/insulin ratio in obese women with metabolic syndrome

Introduction

Visfatin is an adipokine secreted by visceral adipose tissue with insulin-mimetic properties. Higher circulating visfatin levels were reported in type 2 diabetes. The aim of this study was to analyse circulating visfatin and insulin levels and the visfatin/insulin ratio in obese women with and without metabolic syndrome (MetS).

Material and methods

The study involved 92 obese women. Subjects were diagnosed with MetS according to IDF 2005 criteria. The MetS group consisted of 71 subjects (age: 52.8 ±9.4 years, body mass index [BMI]: 39.1 ±5.6 kg/m², waist circumference: 109.6 ±11.4 cm and fat mass: 52.0 ±12.8 kg) while the non-MetS group consisted of 21 subjects (age: 51.7 ±9.5 years, BMI: 36.3 ±5.2 kg/m², waist circumference: 104.7 ±11.0 cm and fat mass: 45.2 ±10.7 kg). In addition to anthropometric measurements and assessment of serum glucose and lipids, plasma concentrations of visfatin were estimated by enzyme-linked immunosorbent assay (ELISA) and of insulin by radioimmunoassay (RIA). Homeostatic model assessment insulin resistance (HOMA-IR) and visfatin/insulin ratio were calculated.

Results

In the MetS group significantly higher (p < 0.01) plasma concentrations of insulin and HOMA-IR values but similar visfatin levels were observed than in the non-MetS group. As a consequence of the significantly higher plasma insulin concentration the visfatin/insulin ratio was significantly lower in the MetS group (p < 0.05). The visfatin/insulin ratio correlated inversely with anthropometric parameters such as body mass, BMI, body fat and waist circumference (r = –0.41, p = 0.0003; r = –0.42, p = 0.0002; r = –0.29, p = 0.01; r = –0.23, p = 0.04, respectively).

Conclusions

We conclude that the visfatin/insulin ratio declining with increasing visceral obesity may predispose to the development of insulin resistance.     

Association between the PPARα-L162V polymorphism and components of the metabolic syndrome

Genetic factors, alone or in interaction with components of the diet, are thought to be involved in the development of the metabolic syndrome. The objective of our study was first to compare the frequency of the peroxisome proliferator-activated receptor (PPAR)-L162V polymorphism in a sample of men with and without the metabolic syndrome as defined by the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATPIII) guidelines, and secondly, to evaluate gene–diet interaction effects on features of the metabolic syndrome. The PPAR-L162V genotype was determined in a sample of 632 men by a polymerase chain reaction–restriction length polymorphism (PCR–RFLP)-based method; fat as well as saturated fat intakes were evaluated by a dietitian-administered food frequency questionnaire. The frequency of the V162 allele was similar in men with (n=281) and without (n=351) the metabolic syndrome ( ²=0.03, p=0.84) but was higher in subjects having simultaneously abdominal obesity, hypertriglyceridemia, and low high-density lipoprotein cholesterol (HDL-C) levels ( ²=3.73, p=0.05). Carriers of the V162 were characterized by higher plasma apolipoprotein B and triglyceride (TG) levels (p=0.10, p=0.004). In a model including the PPAR-L162V polymorphism, fat or saturated fat, its interaction, and covariates (smoking habits, and energy and alcohol intake), the interaction explained a significant percentage of the variance observed in waist circumference (p<0.05). In conclusion, the PPAR-L162V polymorphism alone or in interaction with dietary fat intake is associated with components of the metabolic syndrome.     

Physical activity and sedentary behavior show distinct associations with tissue-specific insulin sensitivity in adults with overweight

Aim

The aim of this study is to investigate associations between the physical activity (PA) spectrum (sedentary behavior to exercise) and tissue-specific insulin resistance (IR).

Methods

We included 219 participants for analysis (median [IQR]: 61 [55; 67] years, BMI 29.6 [26.9; 32.0] kg/m²; 60% female) with predominant muscle or liver IR, as determined using a 7-point oral glucose tolerance test (OGTT). PA and sedentary behavior were measured objectively (ActivPAL) across 7 days. Context-specific PA was assessed with the Baecke questionnaire. Multiple linear regression models (adjustments include age, sex, BMI, site, season, retirement, and dietary intake) were used to determine associations between the PA spectrum and hepatic insulin resistance index (HIRI), muscle insulin sensitivity index (MISI) and whole-body IR (HOMA-IR, Matsuda index).

Results

In fully adjusted models, objectively measured total PA (standardized regression coefficient β = 0.17, p = 0.020), light-intensity PA (β = 0.15, p = 0.045) and moderate-to-vigorous intensity PA (β = 0.13, p = 0.048) were independently associated with Matsuda index, but not HOMA-IR (p > 0.05). A higher questionnaire-derived sport index and leisure index were associated with significantly lower whole-body IR (Matsuda, HOMA-IR) in men but not in women. Results varied across tissues: more time spent sedentary (β = −0.24, p = 0.045) and a higher leisure index (β = 0.14, p = 0.034) were respectively negatively and positively associated with MISI, but not HIRI. A higher sport index was associated with lower HIRI (β = −0.30, p = 0.007, in men only).

Conclusion

While we confirm a beneficial association between PA and whole-body IR, our findings indicate that associations between the PA spectrum and IR seem distinct depending on the primary site of insulin resistance (muscle or liver).     

The effect of aging on T-regulatory cell frequency in HIV infection

T-regulatory cell (T-reg) frequency is increased in HIV infection and with aging. We evaluated the effect of age on total, memory and naïve T-reg percentages in untreated HIV infection. Older HIV⁺ subjects had a total T-reg percent that is 2.8% (p = 0.02) higher than among younger HIV⁺, older HIV⁻ and younger HIV⁻ subjects. In HIV⁺ subjects, the total T-reg percentage is inversely correlated with the lymphocyte proliferative responses to tetanus (r = − 0.45, p = 0.002) and Candida (r = − 0.43, p = 0.003) antigens. Similar correlations were seen between memory T-reg percentages and the lymphocyte proliferative response to tetanus and Candida in HIV⁺ subjects. T-reg percentages did not correlate consistently with markers of immune activation. T-reg percentages are increased in the older HIV⁺ population and may play a role in the accelerated disease progression seen in older HIV-infected persons.     

Effects of stress on heart rate complexity—A comparison between short-term and chronic stress

This study examined chronic and short-term stress effects on heart rate variability (HRV), comparing time, frequency and phase domain (complexity) measures in 50 healthy adults. The hassles frequency subscale of the combined hassles and uplifts scale (CHUS) was used to measure chronic stress. Short-term stressor reactivity was assessed with a speech task. HRV measures were determined via surface electrocardiogram (ECG). Because respiration rate decreased during the speech task (p < .001), this study assessed the influence of respiration rate changes on the effects of interest. A series of repeated-measures analyses of covariance (ANCOVA) with Bonferroni adjustment revealed that short-term stress decreased HR D2 (calculated via the pointwise correlation dimension PD2) (p < .001), but increased HR mean (p < .001), standard deviation of R–R (SD_RR) intervals (p < .001), low (LF) (p < .001) and high frequency band power (HF) (p = .009). Respiratory sinus arrhythmia (RSA) and LF/HF ratio did not change under short-term stress. Partial correlation adjusting for respiration rate showed that HR D2 was associated with chronic stress (r = −.35, p = .019). Differential effects of chronic and short-term stress were observed on several HRV measures. HR D2 decreased under both stress conditions reflecting lowered functionality of the cardiac pacemaker. The results confirm the importance of complexity metrics in modern stress research on HRV.