Comparison of pancreatic volume and fat amount linked with glucose homeostasis between healthy Caucasians and Koreans.

AIM: To compare pancreatic volume and fat amount, and their associations with glucose homeostasis, in a Korean and a white population. MATERIALS AND METHODS: In 43 healthy Korean and 43 healthy white people, matched for age (±3 years) and body mass index (BMI; ±1 kg/m2 ), we measured pancreatic volume and fat amount in the pancreas and abdomen using computed tomography. Pancreatic ß-cell function and insulin resistance were estimated according to biochemical characteristics and a 75-g oral glucose tolerance test. Body composition and resting energy expenditure (REE) were examined using bioimpedance and indirect calorimetry, respectively. RESULTS: The mean ±SD age of the participants was 29.9 ± 5.9 years and 30.0 ± 5.2 years, and BMI was 24.0 ±3.7 and 24.1 ±3.2 kg/m2 in the white participants and the Korean participants, respectively. Pancreatic volume in the white participants was greater than that in Korean participants (77.8 ±11.6 vs 68.2 ±12.1 cm3 ; P < .001). Pancreatic fat content in Korean participants was 22.8% higher than in white participants (P = .051). Insulinogenic index, disposition index, muscle mass and REE were significantly lower in Korean participants. Pancreatic volume was positively associated with indices linked to ß-cell function; fat content in the pancreas was negatively associated with such indices, and positively with insulin resistance after adjusting for relevant variables including REE. CONCLUSIONS: A smaller pancreas and higher fat deposition might be crucial determinants of vulnerability to diabetes in Korean people compared with white people with similar BMI and body fat levels.

Different cut-off values of the insulin tolerance test, the high-dose short Synacthen test (250 µg) and the low-dose short Synacthen test (1 µg) in assessing central adrenal insufficiency.

OBJECTIVE: The short Synacthen test (SST) is widely used as alternative test to the insulin tolerance test (ITT) to investigate central adrenal insufficiency (CAI), but the methodology and cut-off values of the SST are controversial. Our aim was to evaluate the cut-off value of the ITT in normal subjects and to assess the different cut-off values of the high-dose SST (250 µg, HDT) and the low-dose SST (1 µg, LDT) in subjects with suspected CAI. SUBJECTS AND METHODS: We conducted ITTs in 208 normal subjects to establish the cut-off value for the ITT, and 28 of those subjects underwent the HDT and LDT. From 1999 to 2007, 182 patients with suspected CAI were recruited and underwent ITTs, LDTs and HDTs to establish cut-off values and compare the diagnostic accuracy between the LDT and HDT. RESULTS: The 95th percentile of the peak cortisol level during the ITT in the normal control subjects was 14·8 µg/dl. Receiver operator characteristics (ROC) analysis revealed that the optimal cut-off values of peak cortisol in the LDT and HDT in patients with suspected CAI were 15·8 and 17·4 µg/dl, respectively. However, the cut-off values from normative data (mean - 2 SD) were 18·3 µg/dl for the LDT and 20·5 µg/dl for the HDT in normal control. CONCLUSIONS: The optimal cut-off values of SSTs needed to be individualized according to the type of SST and tested patient population.

Polymyxin B, scavenger of endotoxin, enhances isolation yield and in vivo function of islets.

Collagenase purified from bacteria has been used to isolate islets for transplantation. However, collagenase is contaminated with small amounts of endotoxin, which induces dysfunction or apoptosis of islets. In this study, we investigated the effects of polymyxin B, endotoxin scavenger, on the yield and quality of isolated islets. It is revealed that polymyxin B neutralized endotoxin in vitro and inhibited endotoxin-mediated decreases of the glucose stimulation index. Additionally, adenosine triphosphate (ATP) quantitation, islet regression assay, and caspase-3 activation assay demonstrated that polymyxin B efficiently blocked the toxic effects induced by endotoxin. Thereafter, we isolated mouse islets both with and without polymyxin B and compared total islet equivalents (IEQs), glucose-stimulated insulin release, and ATP content. Polymyxin B enhanced islet recovery, and ATP content of islets, and glucose stimulation index, and reduced TNF-alpha expression of islets. Marginal transplantation (200 IEQs/mouse) under the kidney capsule of diabetic mice induced normoglycemia in 30% of the polymyxin B group, but not in any mouse of control group. This result suggests that islets isolated with polymyxin B more effectively lower blood glucose levels as compared with control islets. Thus, polymyxin B could serve as a useful agent in the protection of islets from endotoxin-induced inflammation and apoptosis.

Combined impact of adiponectin and retinol-binding protein 4 on metabolic syndrome in elderly people: the Korean Longitudinal Study on Health and Aging.

The prevalence of metabolic syndrome (MS) increases with progressing and is potentially associated with changes in adipose-derived cytokines, including adiponectin and retinol-binding protein 4 (RBP4). We aimed to determine the prevalence of MS, and the relationships between these factors and MS in elderly people. A population-based cohort study, the Korean Longitudinal Study on Health and Aging (KLoSHA), was performed on subjects aged > or =65 years by random stratified sampling in 2005-2006 (439 men and 561 women). Anthropometrics, biochemical factors including adiponectin and RBP4 levels, body composition, and abdominal fat by computed tomography (CT) were measured. The prevalence of MS was 61.0% in women and 39.9% in men. After adjustment for age, gender, smoking, alcohol, and exercise status and muscle mass, participants with the lowest quartile of adiponectin had a higher risk for having MS than those with the highest quartile (odds ratio (OR) = 4.12, P < 0.01). Similarly, subjects with the highest quartile of RBP4 showed an increased risk for having MS (OR = 1.73, P < 0.01). When both the lowest adiponectin and the highest RBP4 quartiles were combined, the OR increased to 6.22 compared with the opposite quartiles (i.e., highest adiponectin and lowest RBP4 concentrations). Furthermore, circulating levels of adiponectin and RBP4 were significantly correlated with visceral fat and insulin resistance index. In this study, the increased prevalence of MS in elderly but relatively lean population was associated with low adiponectin and high RBP4 levels. The combination of these factors might predict older subjects at high risk for having MS.

Fat in liver/muscle correlates more strongly with insulin sensitivity in rats than abdominal fat.

Intrahepatic or intramuscular lipid (IHL/IML) content has been reported to be correlated with insulin resistance. Visceral fat has also been shown to be associated with insulin resistance. Thus, we investigated whether IHL/IML or visceral fat content is more closely associated with insulin resistance. Twenty Sprague-Dawley rats were divided into two groups based on regular chow diet (RCD) or high-fat diet (HFD; 40% fat). The insulin-sensitivity index (ISI) was determined by euglycemic glucose clamp study, the amount of visceral fat by computed tomography (CT), and the IHL/IML content by magnetic resonance spectroscopy (MRS). Weight, food, and water intake, physical activity, energy expenditure, lipid profile, adiponectin, and high-sensitivity C-reactive protein (hsCRP) levels were measured. At the study end point, visceral fat, and the IHL/IML content were higher in the HFD group than in the RCD group. The IHL/IML content was more highly correlated with ISI than was visceral fat amount. Stronger correlations were also found between adiponectin or hsCRP level and IML/IHL content than visceral fat, especially in the HFD group. Furthermore, the IHL/IML content was significantly associated with the ISI in the multiple regression models but visceral fat was not. There was clear discrimination between RCD and HFD groups in scatter plots of IML/IHL against the ISI, but substantial overlap in that of visceral fat against the ISI. This result suggests that IHL/IML contents are closely related with insulin resistance or atherosclerosis and is a better metabolic index of insulin sensitivity than the visceral fat.