Namseok Lee

Serum Vaspin Concentrations in Human Obesity and Type 2 Diabetes

OBJECTIVE— Vaspin was identified as an adipokine with insulin-sensitizing effects, which is predominantly secreted from visceral adipose tissue in a rat model of type 2 diabetes. We have recently shown that vaspin mRNA expression in adipose tissue is related to parameters of obesity and glucose metabolism. However, the regulation of vaspin serum concentrations in human obesity and type 2 diabetes is unknown. RESEARCH DESIGN AND METHODS— For the measurement of vaspin serum concentrations, we developed an enzyme-linked immunosorbent assay (ELISA). Using this ELISA, we assessed circulating vaspin in a cross-sectional study of 187 subjects with a wide range of obesity, body fat distribution, insulin sensitivity, and glucose tolerance and in 60 individuals with normal glucose tolerance (NGT), impaired glucose tolerance (IGT), or type 2 diabetes before and after a 4-week physical training program. RESULTS— Vaspin serum concentrations were significantly higher in female compared with male subjects. There was no difference in circulating vaspin between individuals with NGT and type 2 diabetes. In the normal glucose-tolerant group, circulating vaspin significantly correlated with BMI and insulin sensitivity. Moreover, physical training for 4 weeks resulted in significantly increased circulating vaspin levels. CONCLUSIONS— We found a sexual dimorphism in circulating vaspin. Elevated vaspin serum concentrations are associated with obesity and impaired insulin sensitivity, whereas type 2 diabetes seems to abrogate the correlation between increased circulating vaspin, higher body weight, and decreased insulin sensitivity. Low circulating vaspin correlates with a high fitness level, whereas physical training in untrained individuals causes increased vaspin serum concentrations.

Serum Progranulin Concentrations May Be Associated With Macrophage Infiltration Into Omental Adipose Tissue

OBJECTIVE—Progranulin is an important molecule in inflammatory response. Chronic inflammation is frequently associated with central obesity and associated disturbances; however, the role of circulating progranulin in human obesity, type 2 diabetes, and dyslipidemia is unknown. RESEARCH DESIGN AND METHODS—For the measurement of progranulin serum concentrations, we developed an enzyme-linked immunosorbent assay (ELISA). Using this ELISA, we assessed circulating progranulin in a cross-sectional study of 209 subjects with a wide range of obesity, body fat distribution, insulin sensitivity, and glucose tolerance and in 60 individuals with normal (NGT) or impaired (IGT) glucose tolerance or type 2 diabetes before and after a 4-week physical training program. Progranulin mRNA and protein expression was measured in paired samples of omental and subcutaneous adipose tissue (adipocytes and cells of the stromal vascular fraction) from 55 lean or obese individuals. Measurement of Erk activation and chemotactic activity induced by progranulin in vitro was performed using THP-1–based cell migration assays. RESULTS—Progranulin serum concentrations were significantly higher in individuals with type 2 diabetes compared with NGT and in obese subjects with predominant visceral fat accumulation. Circulating progranulin significantly correlates with BMI, macrophage infiltration in omental adipose tissue, C-reactive protein (CRP) serum concentrations, A1C values, and total cholesterol. Multivariable linear regression analyses revealed CRP levels as the strongest independent predictor of circulating progranulin. The extent of in vitro progranulin-mediated chemotaxis is similar to that of monocyte chemoattractant protein-1 but independent of Gα. Moreover, in type 2 diabetes, but not in IGT and NGT individuals, physical training for 4 weeks resulted in significantly decreased circulating progranulin levels. CONCLUSIONS—Elevated progranulin serum concentrations are associated with visceral obesity, elevated plasma glucose, and dyslipidemia. We identified progranulin as a novel marker of chronic inflammation in obesity and type 2 diabetes that closely reflects omental adipose tissue macrophage infiltration. Physical training significantly reduces elevated circulating progranulin in patients with type 2 diabetes.

Genetic association study of adiponectin polymorphisms with risk of Type 2 diabetes mellitus in Korean population

Aims  To investigate any association between Type 2 diabetes mellitus and two single nucleotide polymorphisms (SNPs) in the adiponectin gene, T45G and G276T, in the Korean population.

High Plasma Retinol Binding Protein-4 and Low Plasma Adiponectin Concentrations Are Associated with Severity of Glucose Intolerance in Women with Previous Gestational Diabetes Mellitus

CONTEXT Women with previous gestational diabetes mellitus (pGDM) are at high risk of developing type 2 diabetes mellitus in the future. The role of adipokines in women with pGDM has not been established. OBJECTIVE We investigated whether circulating adipokine concentration is associated with abnormal glucose homeostasis in women with pGDM. DESIGN, SETTING, PATIENTS, AND MAIN OUTCOME MEASURES: We measured the plasma concentrations of retinol-binding protein-4 (RBP4), transthyretin (TTR), and adiponectin and metabolic parameters in four groups of women who exhibited normal glucose tolerance (NGT) during a previous pregnancy (NP, n = 17), NGT after GDM (GDM-NGT, n = 72), impaired glucose tolerance after GDM (GDM-IGT, n = 60), and type 2 diabetes after GDM (GDM-DM, n = 8). RESULTS Plasma RBP4 concentration was significantly higher in women with GDM-DM, GDM-IGT, and GDM-NGT than in those with NP. RBP4 concentration correlated positively with TTR concentration; fasting plasma glucose, insulin, and triglyceride concentrations; blood pressure; abdominal fat area; and homeostasis model assessment of insulin resistance. Plasma TTR concentration was elevated in women with GDM-DM compared with other groups. In contrast, adiponectin concentration was lowest in the GDM-DM group and correlated inversely with parameters of insulin resistance. Resistin concentration was higher only in the GDM-NGT and GDM-IGT groups, whereas leptin did not differ between groups. Plasma RBP4 and adiponectin concentrations were inversely correlated. CONCLUSIONS The severity of glucose intolerance in women with pGDM is associated with high RBP4 and low adiponectin concentrations.

High urinary ACE2 concentrations are associated with severity of glucose intolerance and microalbuminuria

OBJECTIVE Angiotensin-converting enzyme 2 (ACE2) plays an important role in glucose metabolism and renal function. However, the relationship between ACE2 and hyperglycemia or microalbuminuria has not been established in humans. We investigated whether urinary ACE2 levels are associated with abnormal glucose homeostasis and urinary albumin excretion. METHODS We developed an ELISA for quantifying ACE2 in urine. The ELISA was used to measure urinary ACE2 levels in 621 subjects with: normal glucose tolerance (NGT; n=77); impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) (n=132); and type 2 diabetes mellitus (T2DM, n=412). Insulin resistance was assessed by homeostasis model assessment for insulin resistance (HOMA-IR) index and urinary albumin excretion by urine albumin-to-creatinine ratio (ACR). Other biochemical and anthropometric parameters were measured. RESULTS Urinary ACE2 levels were significantly higher in insulin-resistant subjects with IFG, IGT, and T2DM than in the NGT group (P<0.001). Urinary ACE2 concentrations appeared to correlate with HOMA-IR, fasting blood glucose, triglyceride, high-sensitivity C-reactive protein, serum creatinine, urinary ACR, and systolic blood pressure (all P<0.05). After adjustment for impaired renal function and other metabolic parameters, urinary ACE2 concentration was still associated with a higher risk for T2DM (OR 1.80, 95% CI 1.05-3.08, P=0.02). In addition, urinary ACE2 levels were highly predictive of microalbuminuria after adjusting for clinical risk factors (OR 2.68, 95% CI 1.55-4.64, P<0.001). CONCLUSION Our data suggest that the urinary ACE2 level is closely associated with T2DM and is an independent risk factor for microalbuminuria.

Effects of a Combined Aerobic and Resistance Exercise Program on C1q/TNF-Related Protein-3 (CTRP-3) and CTRP-5 Levels

OBJECTIVE To examine the effect of a combined exercise program on C1q/tumor necrosis factor-related protein (CTRP) 3 and CTRP-5 levels and novel adiponectin paralogs suggested to be links between metabolism and inflammation and to evaluate sex differences and association with cardiometabolic risk factors in humans with use of a newly developed ELISA. RESEARCH DESIGN AND METHODS This cross-sectional study explored the implications of CTRP-3 and CTRP-5 on cardiometabolic parameters in 453 nondiabetic Korean adults. In addition, we evaluated the impact of a 3-month combined exercise program on CTRP-3 and CTRP-5 levels in 76 obese women. The exercise program consisted of 45 min of aerobic exercise at an intensity of 60–75% of the age-predicted maximum heart rate (300 kcal/session) and 20 min of resistance training (100 kcal/session) five times per week. RESULTS Both CTRP-3 and CTRP-5 concentrations were significantly higher in women (P < 0.001) than in men (P = 0.030). In a multiple stepwise regression analysis, CTRP-3 levels were independently associated with age, sex, and triglyceride, LDL cholesterol, adiponectin, and retinol-binding protein 4 (RBP4) levels (R2 = 0.182). After 3 months of a combined exercise program, cardiometabolic risk factors, including components of metabolic syndrome, insulin resistance, and RBP4 levels, decreased significantly. In particular, CTRP-3 levels decreased significantly (median [interquartile range] 444.3 [373.8–535.0] to 374.4 [297.2–435.9], P < 0.001), whereas CTRP-5 levels were slightly increased (34.1 [28.6–44.3] to 38.4 [29.8–55.1], P = 0.048). CONCLUSIONS A 3-month combined exercise program significantly decreased CTRP-3 levels and modestly increased CTRP-5 levels in obese Korean women.

Urinary adiponectin concentration is positively associated with micro- and macro-vascular complications

BackgroundA relationship between plasma adiponectin level and a number of metabolic conditions, including insulin resistance, obesity, and type 2 diabetes, has been reported. This study aimed to assess whether urinary adiponectin concentration is correlated with vascular complications.MethodsThe study comprised 708 subjects who enrolled in the Seoul Metro City Diabetes Prevention Program and were carefully monitored from September 2008 to December 2008. Levels of urinary adiponectin were measured using an enzyme linked immunosorbent assay (ELISA) kit (AdipoGen, Korea). Urinary albumin excretion was assessed by the ratio of urinary albumin to creatinine (A/C ratio). Participants were divided into three groups based on tertiles of urinary adiponectin concentration, and we investigated whether urinary adiponectin levels are associated with microalbuminuria and pulse wave velocity.ResultsUrinary adiponectin concentrations were significantly higher in subjects with microalbuminuria than subjects with normoalbuminuria (P < 0.001). Urinary adiponectin concentration was positively correlated with age, fasting plasma glucose level, HbA1C level, triglyceride level, HOMA-IR, systolic/diastolic blood pressure, and urinary A/C ratio (all P < 0.05). Subjects in the highest tertile of urinary adiponectin concentration had an increased likelihood of microalbuminuria than those in the lowest tertile (Odds ratio (OR), 6.437; 95% confidence interval (CI), 4.202 to 9.862; P < 0.001). After adjusting for age, sex, and estimated creatinine clearance rate (eCcr), the OR remained significant (OR, 5.607; 95% CI, 3.562 to 8.828; P < 0.001). Backward multiple linear regression analysis revealed urinary adiponectin concentration to be a significant determinant of mean brachial-ankle pulse wave velocity (baPWV).ConclusionsAn increased urinary adiponectin concentration is significantly associated with microalbuminuria and increased mean baPWV. These results suggest that urinary adiponectin may play an important role as a biomarker for vascular dysfunction.

Natural Language Processing for Modeling Stable Writing Characteristics of Users

The aim of this study was to propose a new method to model writing characteristics of users with consistency. This study explored the possibility of modeling the characteristics by analyzing linguistic features of drafts and written comments of the same users in a peer review system. The drafts and comments were collected from 41 undergraduate students who were taking an introductory physics course in the U.S. Natural language processing was used for analyzing drafts and written comments produced by the participants. The results of this study showed that users who wrote drafts by using abstract nouns, different words across sentences, and structurally complex sentences, tended to write comments with abstract nouns, diverse words, and structurally complex sentences. These results implied that users’ stable writing characteristics could be modeled based on linguistic features such as ambiguity, lexical diversity, and syntactic complexity.

Identifying students' writing styles by using computational linguistic approach

The purpose of this study was to identify stable writing styles of students for implementing the cognitive learning system of writing education. According to the previous research, writing styles of writers could be reflected by the linguistic features of writing such as ambiguity, cohesion, lexical diversity, and syntactic complexity. This study explored the method of capturing students’ writing styles by investigating the similarity of linguistic features between drafts and comments written by the same students in a peer review system. The computational linguistic tool, Coh-Merix, was used for analyzing the linguistic features of drafts and comments produced by 41 undergraduate students. The results of this study showed that there was similarity between drafts and comments in the measures of ambiguity, lexical diversity, and syntactic complexity, whereas there was difference in the measures of cohesion.