Relationship of regional fat distribution and obesity to electrocardiographic parameters in healthy premenopausal women

Abdominal obesity is an independent cardiovascular risk factor. The coexistence of abdominal obesity and electrocardiographic abnormalities may facilitate the development of cardiac arrhythmias and sudden death. We determined the relationship of body fat distribution and obesity to ECG indices in 27 obese premenopausal women on an isocaloric diet. Intra-abdominal fat distribution was assessed by computerized tomography, and obesity was assessed by hydrostatic weighing. The PR, QRS, and QTc intervals, the P and QRS axes, and the P-QRS angle were determined from a resting electrocardiogram. Cardiovascular risk profile was assessed by systolic and diastolic blood pressure and plasma cholesterol and triglyceride levels. Increased deposition of intra-abdominal fat was significantly associated with prolongation of the QTc interval independent of obesity and other cardiovascular risk factors. The prolongation of the QTc interval seen with increasing intra-abdominal fat distribution may enhance susceptibility to cardiac arrhythmias. These subjects should have electrocardiographic monitoring during periods of weight loss achieved by intensive regimens.     

Impact of obesity on metabolism in men and women. Importance of regional adipose tissue distribution.

The distribution of adipose tissue thickness, fat cell weight (FCW), and number (FCN) were studied in four regions in randomly selected middle-aged men and women and in 930 obese individuals. Both the obese and the randomly selected men were found to have the largest adipose tissue thickness in the abdominal region. Women, however, showed a relative preponderance for the gluteal and femoral regions. FCW increased with expanding body fat up to a maximal size of approximately 0.7-0.8 micrograms/cell in each region. After this increase in FCW, a more rapid increase in FCN was found. For the same degree of relative overweight, men had higher triglyceride, fasting glucose, and insulin levels; higher sums of glucose and insulin levels during an oral glucose tolerance test; and higher blood pressure. Furthermore, elevated fasting glucose levels (greater than 7.4 mM) occurred twice as often in the males. These differences between males and females persisted even after body fat matching. A male risk profile was seen in women characterized by abdominal obesity (high waist/hip circumference ratio) as compared to women with the typical peripheral obesity. Stepwise multiple regression analyses in both women and men showed the obesity complications to be associated in a first step to waist/hip circumference or body fat and in a second to abdominal fat cell size. It may thus be concluded that: (a) In both obese and nonobese subjects, regional differences exist between the sexes with regard to adipose tissue distribution. (b) Moderate expansion of body fat is mainly due to FCW enlargement, which is subsequently followed by increased FCN. (c) Men and women with a male abdominal type of obesity are more susceptible to the effect of excess body fat on lipid and carbohydrate metabolism.     

Leptin secretion from adipose tissue in women. Relationship to plasma levels and gene expression.

The role of expression and secretion of the ob gene product, leptin, for the regulation of plasma leptin levels has been investigated in vitro using abdominal subcutaneous adipose tissue of 20 obese, otherwise healthy, and 11 nonobese women. Body mass index (BMI, mean+/-SEM; kg/m2) in the two groups was 41+/-2 and 23+/-1, respectively. Fat cell volume was 815+/-55 pl in the obese and 320+/-46 pl in the nonobese group. In the obese group, plasma leptin concentrations and adipose leptin mRNA (relative to gamma actin) were increased five and two times, respectively. Moreover, adipose tissue secretion rates per gram lipid weight or per fat cell number were also increased two and seven times, respectively, in the obese group. There were strong linear correlations (r = 0.6-0.8) between plasma leptin, leptin secretion, and leptin mRNA. All of these leptin measurements correlated strongly with BMI and fat cell volume (r = 0.7- 0.9). About 60% of the variation in plasma leptin could be attributed to variations in leptin secretion rate, BMI, or fat cell volume. We conclude that elevated circulating levels of leptin in obese women above all result from accelerated secretion rates of the peptide from adipose tissue because of increased ob gene expression. However, leptin mRNA, leptin secretion, and circulating leptin levels are all more closely related to the stored amount of lipids in the fat cells of adipose tissue than they are to an arbitrary division into obese versus nonobese.     

Relation of cortisol levels and bone mineral density among premenopausal women with major depression

We aimed to investigate the relationship between cortisol levels and bone mineral density (BMD) among premenopausal women with major depression. We compared BMD, plasma cortisol, osteocalcin and C-telopeptide (CTx) levels of 36 premenopausal women with major depression with 41 healthy women who were matched for age and body mass index. Osteocalcin and CTx were used for the evaluation of bone turnover. The clinical diagnosis of major depression was made by using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria. The 21-item Hamilton Rating Scale for Depression was used for the assessment of depressive symptoms. In comparison with the controls, the mean BMD of the depressed women was significantly lower at the lumbar spine and at all sites of the proximal femur (p = 0.02, 0.01). Plasma cortisol levels were significantly higher in depressive patients than in controls (p = 0.001). Osteocalcin was lower and CTx was higher in the patient group than in controls (p = 0.04, p = 0.008). Lumbar and femur BMD scores were negatively correlated with cortisol levels in the patient group. Major depression had important effects on BMD and bone turnover markers. Depression should be considered among risk factors for osteoporosis in premenopausal women.     

Regional variation in adipose tissue lipoprotein lipase activity: association with plasma high density lipoprotein levels

The associations of adipose tissue lipoprotien lipase (AT-LPL) activity with body fatness and plasma lipoprotein levels were studied in the light of the recently described regional differences in AT-LPL activity. In this regard, heparin-releasable LPL activity was measured in abdominal and femoral adipose tissues of 29 pre-menopausal women. Body fatness variables were all positively correlated with abdominal and femoral AT-LPL activities expressed per 10(6) cells. However, abdominal and femoral AT-LPL activities expressed per unit of cell surface displayed divergent association patterns with body fatness and plasma lipoprotein levels. Indeed, only abdominal AT-LPL activity remained significantly correlated with body fatness variables after adjustment for fat cell surface. Furthermore, whereas abdominal AT-LPL activity tended to be negatively correlated with plasma HDL-cholesterol levels, femoral AT-LPL activity was positively correlated with plasma HDL2-cholesterol (r = 0.40, P less than 0.05) concentration and with the HDL2-cholesterol/HDL3-cholesterol ratio (r = 0.49, P less than 0.01). These results demonstrate the importance of taking into account the regional variation in metabolic activity of adipose tissue when studying its associations with body fatness, and with plasma lipoprotein levels. The lack of association between abdominal AT-LPL activity and plasma HDL2-cholesterol levels lead us to suggest that AT-LPL activity may not be causally related with plasma HDL levels.     

Alterations in plasma and tissue lipids associated with obesity and metabolic syndrome

The MS (metabolic syndrome) is a cluster of clinical and biochemical abnormalities characterized by central obesity, dyslipidaemia [hypertriglyceridaemia and decreased HDL-C (high-density lipoprotein cholesterol)], glucose intolerance and hypertension. Insulin resistance, hyperleptinaemia and low plasma levels of adiponectin are also widely related to features of the MS. This review focuses on lipid metabolism alterations associated with the MS, paying special attention to changes in plasma lipids and cellular fatty acid oxidation. Lipid metabolism alterations in liver and peripheral tissues are addressed, with particular reference to adipose and muscle tissues, and the mechanisms by which some adipokines, namely leptin and adiponectin, mediate the regulation of fatty acid oxidation in those tissues. Activation of the AMPK (AMP-dependent kinase) pathway, together with a subsequent increase in fatty acid oxidation, appear to constitute the main mechanism of action of these hormones in the regulation of lipid metabolism. Decreased activation of AMPK appears to have a role in the development of features of the MS. In addition, alteration of AMPK signalling in the hypothalamus, which may function as a sensor of nutrient availability, integrating multiple nutritional and hormonal signals, may have a key role in the appearance of the MS.     

Sex hormone-binding globulin levels in middle-aged premenopausal women. Associations with visceral obesity and metabolic profile.

OBJECTIVE: Low sex hormone-binding globulin (SHBG) levels in women are associated not only with hyperinsulinemia, increased risk for cardiovascular disease, and type 2 diabetes but also with excess body fatness and abdominal obesity. We tested the hypothesis that an elevated total or intra-abdominal adipose tissue accumulation mediates the relationship between low SHBG levels and an altered metabolic profile. RESEARCH DESIGN AND METHODS: We measured body composition (dual-energy X-ray absorptiometry [DEXA]) and body fat distribution (computed tomography) in 52 middle-aged (46.7 +/- 0.4, mean +/- SEM) premenopausal women. Insulin and glucose responses to a 75-g oral glucose load and plasma lipid-lipoprotein levels were also measured. RESULTS: Low plasma SHBG concentrations were associated with increased total body fat mass (r = -0.41, P < 0.005) and subcutaneous abdominal (r = -0.39, P < 0.005) and intra-abdominal (r = -0.37, P < 0.008) adipose tissue area. Low SHBG was also associated with a greater insulin response to oral glucose (r = -0.40, P < 0.005), higher triglyceride levels (r = -0.29, P < 0.05), higher cholesterol/HDL cholesterol ratio (r = -0.51, P < 0.005), but lower HDL cholesterol concentrations (r = 0.65, P < 0.005). When matched for intra-abdominal fat or total fat mass, subjects with either low or high SHBG showed no difference in the insulin response to an oral glucose challenge. Statistical adjustment for differences in intra-abdominal adipose tissue accumulation or total body fat mass also eliminated the associations between SHBG levels and metabolic variables, with the exception of the association between SHBG and HDL cholesterol levels (r = 0.52, P < 0.005). CONCLUSIONS: Our results suggest that the previously reported relationship between low SHBG levels and increased metabolic disease risk in women is mediated, to a large extent, by concomitant variation in body fatness and intra-abdominal adipose tissue accumulation.     

Heterogeneity of plasma insulin and triglyceride levels in obesity demonstrated by family study.

Fifty relatives of 7 families with high prevalence of obesity were investigated and the possibility was shown that there were three forms of familial obesity--normoinsulinemic obesity, hyperinsulinemic obesity and diabetic obesity. In normoinsulinemic obesity, both glucose tolerance and plasma lipids were normal with a few exceptions whereas in hyperinsulinemic obesity, mild glucose intolerance and manifest hyperlipidemia, and in diabetic obesity, blunted insulinogenic index and more advanced glucose intolerance with slight hyperlipidemia existed.     

Association between regional adipose tissue distribution and both type 2 diabetes and impaired glucose tolerance in elderly men and women

OBJECTIVE: We examined whether regional adipose tissue distribution, specifically that of skeletal muscle fat and visceral abdominal fat aggregation, is characteristic of elderly individuals with hyperinsulinemia, type 2 diabetes, and impaired glucose tolerance (IGT). RESEARCH DESIGN AND METHODS: A total of 2,964 elderly men and women (mean age 73.6 years) were recruited for cross-sectional comparisons of diabetes or glucose tolerance, generalized obesity with dual-energy X-ray absorptiometry, and regional body fat distribution with computed tomography. RESULTS-Approximately one-third of men with type 2 diabetes and less than half of women with type 2 diabetes were obese (BMI > or =30 kg/m(2)). Despite similar amounts of subcutaneous thigh fat, intermuscular fat was higher in subjects with type 2 diabetes and IGT than in subjects with normal glucose tolerance (NGT) (11.2 +/- 9.4, 10.3 +/- 5.8, and 9.2 +/- 5.9 cm(2) for men; 12.1 +/- 6.1, 10.9 +/- 6.5, and 9.4 +/- 5.3 cm(2) for women; both P < 0.0001). Visceral abdominal fat was also higher in men and women with type 2 diabetes and IGT than in subjects with NGT (172 +/- 79, 163 +/- 72, and 145 +/- 66 cm(2) for men; 162 +/- 66, 141 +/- 60, and 116 +/- 54 cm(2) for women; both P < 0.0001 across groups). Higher rates of intermuscular fat and visceral abdominal fat were associated with higher fasting insulin in normal-weight (BMI <25 kg/m(2)) men (r = 0.24 for intermuscular fat, r = 0.37 for visceral abdominal fat, both P < 0.0001) and women (r = 0.20 for intermuscular fat, r = 0.40 for visceral abdominal fat, both P < 0.0001). These associations were not found in obese subjects. CONCLUSIONS: Elderly men and women with normal body weight may be at risk for metabolic abnormalities, including type 2 diabetes, if they possess an inordinate amount of muscle fat or visceral abdominal fat.     

Age-related increase in visceral adipose tissue and body fat and the metabolic risk profile of premenopausal women.

OBJECTIVE: Age-related differences in body fat and, more specifically, in the accumulation of abdominal visceral adipose tissue (AT) were examined as potential covariates of the age-related difference in the metabolic profile predictive of cardiovascular disease (CVD) risk observed in young, as compared with middle-aged, premenopausal women. RESEARCH DESIGN AND METHODS: Body composition, AT distribution, plasma lipoprotein-lipid levels, glucose tolerance, and plasma insulin concentrations were assessed in a sample of 122 young women (27.4+/-7.5 years, mean +/- SD) and compared with a sample of 52 middle-aged premenopausal women (49.5+/-5.3 years) who still had a normal menstrual cycle. RESULTS: Middle-aged women were characterized by elevated levels of total abdominal and visceral AT and greater body fat mass and waist circumference, as well as by higher plasma levels of total cholesterol, LDL cholesterol, apolipoprotein (apo)B, and LDL-apoB compared with younger women. Furthermore, middle-aged women showed a greater glycemic response to a 75-g oral glucose load than young women (P < 0.01). In both young and middle-aged subjects, visceral AT accumulation was significantly correlated with plasma triglyceride, apoB, and LDL-apoB levels and with the cholesterol/HDL cholesterol ratio, as well as with plasma glucose, insulin, and C-peptide levels measured in the fasting state and after the oral glucose load, and negatively correlated with HDL cholesterol levels (-0.41 < or = r < or = 0.65, P < 0.05). When variables were adjusted for levels of visceral AT and fat mass, age-related differences that were initially found in plasma apoB and LDL-apoB levels, as well as in fasting glycemia and glucose tolerance, were eliminated. CONCLUSIONS: Results of the present study suggest that even before the onset of menopause there is an age-related deterioration in the metabolic risk profile and an increase in visceral AT deposition in middle-aged women compared with young control subjects. Furthermore, our results provide support for the notion that the age-related increase in visceral AT accumulation is a significant factor involved in the deterioration of the CVD risk profile noted in premenopausal women with age.     

胰岛素抵抗人群皮下脂肪组织中脂肪甘油三酯脂酶和激素敏感性脂肪酶表达减低

目的 通过检测胰岛素抵抗人群皮下脂肪组织中脂肪甘油三酯脂酶(ATGL)和激素敏感性脂肪酶(HSL)的表达,探讨脂肪动员异常与胰岛素抵抗的关系及在胰岛素抵抗中的作用.方法 选则本院择期行腹腔镜胆囊切除术的住院患者55例,根据胰岛素抵抗指数,将患者分为胰岛素敏感组27例和胰岛素抵抗组28例.在手术过程中取皮下脂肪组织.采用半定量逆转录聚合酶链反应测定脂肪组织中ATGL、HSLmRNA的表达,采用Westernblot法测定脂肪组织中ATGL、HSL蛋白的表达.结果 胰岛素抵抗组的体质量指数、腰臀比、血清甘油三酯、血清空腹胰岛素及游离脂肪酸水平均明显高于胰岛素敏感组,体质量指数25.31±1.54 vs 23.11±1.03,腰臀比0.98±0.24 vs 0.75±0.15,甘油三酯(1.98±0.56)mmol/L VS(1.04±0.24)mmol/L,空腹胰岛素(25.87±14.21)mU/LVS(11.15±4.67)mU/L.游离脂肪酸(1.35±0.46)mmol/L vs (0.66±0.23)mmol/ L(P<0.01).胰岛素抵抗组皮下脂肪组织中ATGL mRNA和蛋白表达均明显低于胰岛素敏感组,0.92±0.13 vs 2.03±0.21、1.03±0.08 vs 1.98±0.11(P<0.01);HSL mRNA和蛋白表达也均明显低于胰岛素敏感组,1.35±0.21 vs 1.64±0.12、1.25±0.09 VS 1.42±0.15(P<0.01).ATGL的蛋白表达与空腹胰岛素、胰岛素抵抗指数及游离脂肪酸呈负相关(r=-0.235、-0.356和-0.214,P<0.01或<0.05);HSL 的蛋白表达与空腹胰岛素、游离脂肪酸和腰臀比呈负相关(r=-0.185、-0.246和-0.145,P<0.01或<0.05).结论 胰岛素抵抗状态时皮下脂肪组织中ATGL和HsL的表达减低.     

Daytime triglyceride variability in men and women with different levels of triglyceridemia

BackgroundTriglyceride (TG) levels measured in either the fasting or non-fasting state predict the risk of cardiovascular disease (CVD). Since CVD risk assessment is affected by variability in TG, the aim of the study was to investigate intra-individual variability of non-fasting TG.MethodsCapillary triglyceride (cTG) levels were measured in 246 free-living individuals at six time-points during the day on three separate occasions. Intra-individual variability in cTG was assessed by calculating the standard deviation of three measures at each time-point. Subjects were analyzed by gender and by fasting TG level.ResultsIn the fasting state, intra-individual variability was similar in males and females (0.28 and 0.35 mmol/l, respectively), but increased significantly in male but not in female subjects during the day, i.e., 0.28 to 0.69, and 0.35 to 0.36 mmol/l, resp. Subjects with higher fasting TG levels had greater absolute variability in both fasting and non-fasting TG.ConclusionsThe variability in non-fasting TG is greater in males and in individuals with higher levels of TG. Since greatest variability in non-fasting TG occurs very late in the day, it is unlikely to affect the assessment of CVD risk, which is based on a blood sample taken during daylight hours.     

Visceral adipose tissue cutoffs associated with metabolic risk factors for coronary heart disease in women

OBJECTIVE: This study determined whether there is a critical level of visceral adipose tissue (VAT) associated with elevated coronary heart disease (CHD) risk factors in a cohort of women >45 years of age. RESEARCH DESIGN AND METHODS: Measurements of body composition (dual-energy X-ray absorptiometry), body fat distribution (computed tomography), fasting and 2-h postprandial (75-g) glucose concentrations, and fasting lipoprotein lipid and insulin concentrations were performed in 233 perimenopausal (9%) and postmenopausal women (age 59 +/- 6 years, 79% Caucasian, 16% on hormone replacement therapy). RESULTS: Women in the lowest VAT quintile (< or =105 cm(2)) had higher concentrations of HDL and HDL(2) cholesterol, lower LDL/HDL cholesterol ratios and triglyceride concentrations, and lower fasting glucose and insulin concentrations than women in the remaining four quintiles (P values <0.05-0.001). Women in the second lowest VAT quintile (106-139 cm(2)) had higher HDL and HDL(2) cholesterol and lower LDL/HDL ratios than women with a VAT > or =163 cm(2) (P < 0.05). Logistic regression analyses showed that women with a VAT of 106-162 cm(2) are 2.5 times more likely to have a low HDL cholesterol (P < 0.05), while women with a VAT > or =163 cm(2) are 5.5 times more likely to have a low HDL cholesterol (P < 0.01) and approximately 4.0 times more likely to have a high LDL/HDL ratio (P < 0.05) compared with women with a VAT < or =105 cm(2). Women with a VAT > or =163 cm(2) are at a higher risk of having impaired glucose tolerance (P < 0.01). CONCLUSIONS: A VAT > or =106 cm(2) is associated with an elevated risk, and a VAT > or =163 cm(2) with an even greater risk, for these metabolic CHD risk factors compared with women with a VAT < or =105 cm(2). These values may prove useful for defining "visceral obesity" and for identifying women most likely to benefit from preventative interventions.     

Plasma apolipoprotein CI and CIII levels are associated with increased plasma triglyceride levels and decreased fat mass in men with the metabolic syndrome

OBJECTIVE—To determine whether, in accordance with observations in mouse models, high concentrations of the lipoprotein lipase inhibitors apolipoprotein (Apo) CI and ApoCIII are associated with increased triglyceride concentrations and decreased fat mass in men with the metabolic syndrome.RESEARCH DESIGN AND METHODS—Plasma ApoCI, ApoCIII, and triglyceride concentrations were measured in the postabsorptive state in 98 men with the metabolic syndrome. Subcutaneous and visceral fat areas were measured by 3T-magnetic resonance imaging.RESULTS—Triglyceride concentrations were 49% higher, and the average visceral fat area was 26% lower (both P < 0.001), in subjects with high ApoCI and ApoCIII compared with low ApoCI and ApoCIII. Subjects with either high ApoCI or ApoCIII had 16% (P < 0.05) and 18% (P < 0.01) decreased visceral fat area, respectively.CONCLUSIONS—High concentrations of ApoCI and ApoCIII are associated with increased triglycerides and decreased visceral fat mass in men with the metabolic syndrome. These findings translate mouse studies into human pathophysiology.Apolipoprotein (Apo) CI and ApoCIII are present on HDL and triglyceride (TG)-rich lipoproteins (1) and mainly affect plasma lipid metabolism by inhibition of lipoprotein lipase (LPL) (2). This enzyme hydrolyzes TG in VLDL and chylomicrons, releasing fatty acids for storage by adipocytes or for energy metabolism in muscles (2,3). Overexpression of human ApoCI in mice increases VLDL-associated TG plasma levels in combination with decreased body fat (4). The effect of ApoCIII overexpression is unknown, but ApoCIII deficiency in mice led to lower VLDL-associated TG levels and increased diet-induced obesity (5). Because it has recently been shown that LPL activity is higher in visceral adipose tissue (VAT) compared with subcutaneous adipose tissue (SAT) (6), LPL inhibitors such as ApoCI and ApoCIII may differentially affect VAT compared with SAT. The objective of this study was to determine whether, like in mouse models, high ApoCI and ApoCIII concentrations are associated with increased TG concentrations and decreased fat mass (VAT vs. SAT) in men with the metabolic syndrome.