Plasma adiponectin levels in overweight and obese Asians

OBJECTIVE: Hypoadiponectin has been documented in subjects with obesity, diabetes mellitus, or coronary heart disease, suggesting a potential use of plasma adiponectin in following the clinical progress in subjects with metabolic syndrome (MS). In this study, we investigated the plasma adiponectin levels in relation to the variables of MS among overweight/obese Asian subjects. RESEARCH METHODS AND PROCEDURES: The plasma adiponectin, anthropometric and biochemical measurements, oral glucose tolerance tests (OGTT), and modified insulin suppression tests were performed on 180 overweight/obese Asian subjects [body mass index (BMI) >or= 23 kg/m(2)], including 47 subjects with morbid obesity (BMI >or= 40 kg/m(2)). RESULTS: The plasma adiponectin levels negatively correlated with BMI, waist-to-hip ratio, fasting plasma glucose, insulin, triglyceride, uric acid levels, hyperinsulinemia, and glucose intolerance in OGTT, but positively with high-density lipoprotein-cholesterol. In contrast, they were not related to blood pressure and total cholesterol. Moreover, insulin sensitivity, measured by quantitative insulin sensitivity check index (QUICKI) or in insulin suppression tests, significantly correlated with the plasma adiponectin levels. Among morbidly obese subjects, only the waist-to-hip ratio correlated with the plasma adiponectin levels. Using multivariate linear regression models, the area under curve of plasma glucose in OGTT and high-density lipoprotein-cholesterol among the overweight/obese subjects and WHR among the morbidly obese subjects were significantly related to the plasma adiponectin levels after adjustment for other variables. DISCUSSION: In overweight/obese Asians, the plasma adiponectin levels significantly correlated with various indices of MS except hypertension. Whether the plasma adiponectin level could be a suitable biomarker for following the clinical progress of MS warrants further investigation.     

Effect of lifestyle modification on adipokine levels in obese subjects with insulin resistance

OBJECTIVE: To study the effect of weight loss in response to a lifestyle modification program on the circulating levels of adipose tissue derived cytokines (adipokines) in obese individuals with insulin resistance. RESEARCH METHODS AND PROCEDURES: Twenty-four insulin-resistant obese subjects with varying degrees of glucose tolerance completed a 6-month program consisting of combined hypocaloric diet and moderate physical activity. Adipokines [leptin, adiponectin, resistin, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6)] and highly sensitive C-reactive protein were measured before and after the intervention. Insulin sensitivity index was evaluated by the frequently sampled intravenous glucose tolerance test. RESULTS: Participants had a 6.9 +/- 0.1 kg average weight loss, with a significant improvement in sensitivity index and reduction in plasma leptin (27.8 +/- 3 vs. 23.6 +/- 3 ng/mL, p = 0.01) and IL-6 (2.75 +/- 1.51 vs. 2.3 +/- 0.91 pg/mL, p = 0.012). TNF-alpha levels tended to decrease (2.3 +/- 0.2 vs. 1.9 +/- 0.1 pg/mL, p = 0.059). Adiponectin increased significantly only among diabetic subjects. The reductions in leptin were correlated with the decreases in BMI (r = 0.464, p < 0.05) and with changes in highly sensitive C-reactive protein (r = 0.466, p < 0.05). DISCUSSION: Weight reduction in obese individuals with insulin resistance was associated with a significant decrease in leptin and IL-6 and a tendency toward a decrease in circulating TNF-alpha, whereas adiponectin was increased only in diabetic subjects. Further studies are needed to elucidate the relationship between changes of adipokines and the health benefits of weight loss.     

Plasma cortisol levels and workers exposed to urban pollutants

Studies on animals and human subjects have proposed that urban pollutants may cause alterations of cortisol levels. The aim of this study is to evaluate whether police officers exposed to urban pollutants and possible psycho-social stressors could be at risk for alterations on plasma cortisol levels compared to a control group. Plasma cortisol levels were determined in 302 police officers with outdoor activity and administrative workers with indoor activity. The subjects were subdivided into three groups: "A" (non-smokers and non-drinkers), "B" (smokers), and "C" group (drinkers). In male and female subjects of "A" and "C" groups and in female subjects of "B" group the mean cortisol values were significantly higher in police officers compared to controls. The authors hypothesise an effect on plasma cortisol levels in police officers exposed to chemical, physical and possible psycho-social stressors.     

Plasma and urinary carnitine of obese subjects on very-low-calorie diets

We evaluated the differential effects of feeding two very-low-calorie diets upon the fractions of plasma and urinary carnitine in obese females. Ten subjects received either diet D1, a 420 kcal/day formula diet, or diet D2, a 500-600 kcal/day meat/fish/poultry diet. Plasma and urinary carnitine levels were determined at the start of the study. After 1 month, plasma carnitine levels were obtained; at 2 months, both plasma and urinary carnitine levels were obtained. Subjects receiving diet D2 showed significantly higher levels of plasma total carnitine over the course of the study (p less than 0.05). Plasma short-chain acylcarnitine esters increased and free carnitine declined significantly in both groups during the study period. Subjects receiving D1 excreted significantly less urinary carnitine than those receiving D2. We conclude that long-term ingestion of very-low-calorie diets causes alterations in plasma carnitine metabolism.     

Krill oil significantly decreases 2-arachidonoylglycerol plasma levels in obese subjects

We have previously shown that krill oil (KO), more efficiently than fish oil, was able to downregulate the endocannabinoid system in different tissues of obese zucker rats.We therefore aimed at investigating whether an intake of 2 g/d of either KO or menhaden oil (MO), which provides 309 mg/d of EPA/DHA 2:1 and 390 mg/d of EPA/DHA 1:1 respectively, or olive oil (OO) for four weeks, is able to modify plasma endocannabinoids in overweight and obese subjects.The results confirmed data in the literature describing increased levels of endocannabinoids in overweight and obese with respect to normo-weight subjects. KO, but not MO or OO, was able to significantly decrease 2-arachidonoylglycerol (2-AG), although only in obese subjects. In addition, the decrease of 2-AG was correlated to the plasma n-6/n-3 phospholipid long chain polyunsaturated fatty acid (LCPUFA) ratio. These data show for the first time in humans that relatively low doses of LCPUFA n-3 as KO can significantly decrease plasma 2-AG levels in obese subjects in relation to decrease of plasma phospholipid n-6/n-3 LCPUFA ratio. This effect is not linked to changes of metabolic syndrome parameters but is most likely due to a decrease of 2-AG biosynthesis caused by the replacement of 2-AG ultimate precursor, arachidonic acid, with n-3 PUFAs, as previously described in obese Zucker rats.     

Plasma adiponectin increases postprandially in obese,but not in lean,subjects

OBJECTIVE: We investigated the acute responses of plasma adiponectin levels to a test meal in lean and obese subjects. RESEARCH METHODS AND PROCEDURES: We studied 13 lean and 11 obese subjects after a 10-hour overnight fast. Glucose, insulin, and adiponectin concentrations were measured at baseline and 15, 30, 60, 120, and 180 minutes after a fixed breakfast. RESULTS: At baseline, fasting adiponectin concentrations were lower in the obese group vs. the lean group [mean (95% confidence interval): 2.9 (2.1 to 4.1) microg/mL vs. 8.6 (6.5 to 11.3) microg/mL], but rose 4-fold postprandially in the obese group, reaching a peak at 60 minutes [baseline: 2.9 (2.1 to 4.1) microg/mL vs. 60 minutes: 12.1 (8.5 to 17.4) microg/mL; p< 0.0001] and remaining elevated for the remainder of the study. There were no postprandial changes in plasma adiponectin concentrations in lean subjects. DISCUSSION: This increase of adiponectin concentrations in obese individuals might have important beneficial effects on postprandial glucose and lipid metabolism and might be viewed as a mechanism for maintaining normal glucose tolerance in those who are obese and insulin resistant.     

Plasma levels of tocopherol in sickle cell anemia subjects.

Plasma tocopherol levels of less than 0.8 microgram/g lipid were considered indicative of a vitamin E-deficient status. Based on this criterion, 10 out of 13 sickle cell anemia patients who were not in crisis, were considered deficient in vitamin E as compared to none of 24 normal control subjects. Sickle cell anemia patients treated with 150 IU vitamin E (dl-alpha-tocopheryl acetate) three times a day for 1 to 2 months had plasma tocopherol levels similar to control subjects. The possible role of vitamin E status on the manifestation of sickle cell anemia is discussed. The present study confirmed the vitamin E-deficient status of subjects with beta-thalassemia. Six of seven patients with beta-thalassemia had tocopherol levels of less than 0.8 mg/g lipid.     

Serum ghrelin levels in response to glucose load in obese subjects post-gastric bypass surgery

OBJECTIVE: We sought to elucidate further the mechanisms leading to weight loss after gastric bypass (GBP) surgery in morbidly obese individuals. Ghrelin is a gastroenteric appetite-stimulating peptide hormone, fasting levels of which decrease with increasing adiposity and increase with diet-induced weight loss. In addition, ghrelin levels rapidly decline postprandially. RESEARCH METHODS AND PROCEDURES: We measured serum ghrelin responses to a 75-g oral glucose tolerance test (OGTT) in 6 subjects who had undergone GBP surgery 1.5 +/- 0.7 years before testing and compared these responses with 6 obese subjects about to undergo GBP surgery, 6 obese nonsurgical subjects (matched for BMI to the post-GBP surgical group), and 5 lean subjects. RESULTS: Despite weight loss induced by the GBP surgery, fasting serum ghrelin levels were significantly lower in the post-GBP surgery group than in the lean subject (by 57%) or pre-GBP surgery (by 45%) group. Serum ghrelin levels during the OGTT were significantly lower in postoperative than in lean, obese pre-GBP surgical, or obese nonsurgical subjects. The magnitude of the decline in serum ghrelin levels between 0 and 120 minutes post-OGTT was significantly smaller in postoperative (by 62%), obese pre-GBP surgical (by 80%), or obese nonsurgical (by 69%) subjects in comparison with lean subjects. DISCUSSION: Serum ghrelin levels in response to OGTT are lower in subjects post-GBP surgery than in either lean or obese subjects. Tonically low serum ghrelin levels may be involved in the mechanisms inducing sustained weight loss after GBP surgery.     

Plasma carotenoid levels in human subjects fed a low carotenoid diet.

The purpose of this study was to investigate the effect of a low carotenoid diet on plasma carotenoid levels in humans. Twelve healthy male subjects were fed a low carotenoid diet under controlled conditions for 13 wk in a live-in metabolic unit, as part of a study of vitamin C requirement. Plasma carotenoids (zeaxanthin/lutein, cryptoxanthin, lycopene, alpha-carotene, beta-carotene) were measured with HPLC on study days 2-3, 14-15, 35-36 and 63-64. The rate of decline was rapid between d 2-3 and d 14-15, when the concentration of each carotenoid decreased significantly (P less than 0.05). Although accurate figures for half-life are not possible without more frequent sampling points, mean plasma depletion half-life seemed to be less than 12 d for beta-carotene, alpha-carotene and cryptoxanthin, between 12 and 33 d for lycopene and between 33 and 61 d for zeaxanthin/lutein. Because the decline was not linear over the study period, these data suggest the possibility of at least two body pools of these compounds, with one pool having a more rapid turnover rate. Because there is a significant decline in plasma carotenoid levels within the first 2 wk of a low carotenoid diet, determination of levels of these compounds may be useful only in the assessment of short-term intake.     

Plasma levels of endothelin-1 increase in patients with sarcoidosis and fall after disease remission.

BACKGROUND: Sarcoidosis is a chronic systemic disease, characterized by an imbalance of immunity processes and the presence of granuloma. Endothelin-1, a new vasoactive and bronchoconstrictive peptide, is a powerful mitogen for smooth muscle cells and fibroblasts and plays a role in the inflammation state. We postulate that endothelin-1 has a role in sarcoidosis. METHODS: We studied the behaviour of circulating levels of endothelin-1 in 20 patients with sarcoidosis and its correlation with some biochemical parameters of activity disease, such as erythrocyte sedimentation rate (ESR) and serum angiotensin-converting enzyme (SACE). We measured serum levels of ESR, SACE, calcium and plasma endothelin-1 levels in all patients at the beginning of the study and one again in 9 patients with clinical-biochemical remission of disease after steroid treatment. RESULTS: In patients with sarcoidosis, circulating levels of endothelin-1, SACE and ESR were significantly higher (p<0.001) than those of healthy subjects. Moreover, in patients with pulmonary involvement, there was a significant statistical difference (p<0.001) between endothelin-1 levels and radiological stage compared to normal subjects. In the 9 patients with remission of disease, both endothelin-1 levels and parameters of activity disease normalized. CONCLUSIONS: Our results seem to suggest that the increase of plasma endothelin-1 levels in active sarcoidosis can represent an expression of the endothelial dysfunction and reflect the picture of cellular activation.     

Skinfold thickness measurements in obese subjects

To determine the accuracy of skinfold thickness measurements in body composition assessment, skinfold thicknesses, bioelectrical impedance, body density by underwater weighing, and total body water by deuterium dilution were determined in 105 healthy adults who varied widely in body fatness. Body fat ranged from 2.9% to 61.2% of body weight and a substantial number of obese subjects was included. The correlation between body fat calculated from skinfold equations and body fat measured by underwater weighing was in the same range as that between body fat estimated from impedance and underwater weighing. However, body fat calculated both from skinfold equations and bioelectrical impedance tended to be underestimated compared with body fat calculated from underwater weighing and total body water in the most obese subjects. In obese subjects it was not possible to measure significant numbers of skinfold thicknesses because of the inadequate size of the calipers.     

Effect of glucose tolerance status on PAI-1 plasma levels in overweight and obese subjects

OBJECTIVE: The aim of our study was to examine whether plasminogen activator inhibitor-1 (PAI-1) plasma levels varied as a function of differences in glucose tolerance status independently of body fatness, body-fat distribution, and insulin sensitivity. RESEARCH METHODS AND PROCEDURES: Plasma PAI-1 antigen levels, along with insulin resistance [measured by homeostatic model assessment (HOMA(IR))], central fat accumulation, body composition, blood pressure, and fasting concentrations of glucose, insulin, and lipids, were measured in 229 overweight and obese [body mass index (BMI) > or =25 kg/m(2)) subjects with normal glucose tolerance (NGT) and in 44 age- and BMI-matched subjects with impaired glucose tolerance (IGT). RESULTS: Plasma PAI-1 antigen levels were significantly higher in IGT than in NGT subjects. Log PAI-1 was positively correlated with BMI, HOMA(IR), and log insulin, and inversely associated with high-density lipoprotein-cholesterol both in IGT and in NGT individuals. On the other hand, log PAI-1 was positively correlated with waist circumference, fat mass (FM), fat-free mass, systolic and diastolic blood pressure, and log triglycerides only in the NGT group. After multivariate analyses, the strongest determinants of PAI-1 levels were BMI, FM, waist circumference, and high-density lipoprotein cholesterol in the NGT group and only HOMA(IR) in the IGT cohort. DISCUSSION: This study demonstrates that PAI-1 concentrations are higher in IGT than in NGT subjects. Furthermore, we suggest that the influences of total adiposity, central fat, and insulin resistance, main determinants of PAI-1 concentrations, are different according to the degree of glucose tolerance.