Serum 25-hydroxyvitamin D and insulin resistance in people at high risk of cardiovascular disease: a euglycaemic hyperinsulinaemic clamp study

CONTEXT: In observational studies low serum 25-hydroxyvitamin D (25-OHD) concentration is associated with an increased risk of type 2 diabetes mellitus (DM). Increasing serum 25-OHD may have beneficial effects on insulin resistance or beta-cell function. Cross-sectional studies utilising sub-optimal methods for assessment of insulin sensitivity and serum 25-OHD concentration provide conflicting results.

OBJECTIVE: This study examined the relationship between serum 25-OHD concentration and insulin resistance in healthy overweight individuals at increased risk of cardiovascular disease, using optimal assessment techniques.

METHODS: 92 subjects (mean age 56.0, SD 6.0 years), who were healthy but overweight (mean BMI 30.9, SD 2.3 kg/m(2) ) underwent assessments of insulin sensitivity (two-step euglycaemic hyperinsulinaemic clamp, HOMA2-IR), beta-cell function (HOMA2%B), serum 25-OHD concentration and body composition (DEXA).

RESULTS: Mean total 25-OHD concentration was 32.2, range 21.8 - 46.6 nmol/L. No association was demonstrated between serum 25-OHD concentration and insulin resistance.

CONCLUSIONS: In this study using optimal assessment techniques to measure 25-OHD concentration, insulin sensitivity and body composition, there was no association between serum 25-OHD concentration and insulin resistance in healthy, overweight individuals at high risk of developing cardiovascular disease. This study suggests the documented inverse association between serum 25-OHD concentration and risk of type 2 DM is not mediated by a relationship between serum 25-OHD concentration and insulin resistance. 

Circulating pancreatic polypeptide concentrations predict visceral and liver fat content

CONTEXT AND OBJECTIVE: No current biomarker can reliably predict visceral and liver fat content, both of which are risk factors for cardiovascular disease. Vagal tone has been suggested to influence regional fat deposition. Pancreatic polypeptide (PP) is secreted from the endocrine pancreas under vagal control. We investigated the utility of PP in predicting visceral and liver fat. PATIENTS AND METHODS: Fasting plasma PP concentrations were measured in 104 overweight and obese subjects (46 men and 58 women). In the same subjects, total and regional adipose tissue, including total visceral adipose tissue (VAT) and total subcutaneous adipose tissue (TSAT), were measured using whole-body magnetic resonance imaging. Intrahepatocellular lipid content (IHCL) was quantified by proton magnetic resonance spectroscopy. RESULTS: Fasting plasma PP concentrations positively and significantly correlated with both VAT (r = 0.57, P < .001) and IHCL (r = 0.51, P < .001), but not with TSAT (r = 0.02, P = .88). Fasting PP concentrations independently predicted VAT after controlling for age and sex. Fasting PP concentrations independently predicted IHCL after controlling for age, sex, body mass index (BMI), waist-to-hip ratio, homeostatic model assessment 2-insulin resistance, (HOMA2-IR) and serum concentrations of triglyceride (TG), total cholesterol (TC), and alanine aminotransferase (ALT). Fasting PP concentrations were associated with serum ALT, TG, TC, low- and high-density lipoprotein cholesterol, and blood pressure (P < .05). These associations were mediated by IHCL and/or VAT. Fasting PP and HOMA2-IR were independently significantly associated with hepatic steatosis (P < .01). CONCLUSIONS: Pancreatic polypeptide is a novel predictor of visceral and liver fat content, and thus a potential biomarker for cardiovascular risk stratification and targeted treatment of patients with ectopic fat deposition.

Low-Level Fluoride Exposure Increases Insulin Sensitivity in Experimental Diabetes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Use of Homeostatic Model Assessment Indexes for the Identification of Metabolic Syndrome and Insulin Resistance among Cuban-Americans: A Cross Sectional Study

Aim: to determine cut off points for The Homeostatic Model Assessment Index 1 and 2 (HOMA-1 and HOMA-2) for identifying insulin resistance and metabolic syndrome among a Cuban-American population. Study Design: Cross sectional. Place and Duration of Study: Florida International University, Robert Stempel School of Public Health and Social Work, Department of Dietetics and Nutrition, Miami, FL from July 2010 to December 2011. Methodology: Subjects without diabetes residing in South Florida were enrolled (N=146, aged 37 to 83 years). The HOMA1-IR and HOMA2-IR 90th percentile in the healthy group (n=75) was used as the cut-off point for insulin resistance. A ROC curve was constructed to determine the cut-off point for metabolic syndrome. Results: HOMA1-IR was associated with BMI, central obesity, and triglycerides (P3.95 and >2.20 and for metabolic syndrome were >2.98 (63.4% sensitivity and 73.3% specificity) and >1.55 (60.6% sensitivity and 66.7% specificity), respectively. Conclusion: HOMA cut-off points may be used as a screening tool to identify insulin resistance and metabolic syndrome among Cuban-Americans living in South Florida.

Ethnic Differences in Insulin Resistance, Adiponectin Levels and Abdominal Obesity: Haitian Americans and African Americans, with and without Type 2 Diabetes Mellitus

Background: Metabolic outcomes of obesity and its associated disorders may not be equivalent across ethnicity and diabetes status. Aim: In this paper, we examined the association of abdominal obesity, by ethnicity and diabetes status, for indicators of glucose metabolism in Blacks. Methods: A cross sectional study was conducted in Haitian Americans (n= 186) and African Americans (n= 148) with and without type 2 diabetes mellitus (T2DM). Student’s t-test and Chi-squared test were used to assess differences in mean and proportion values between ethnicities with and without type 2 diabetes mellitus. Relationship between insulin resistance, ethnicity, diabetes status, abdominal obesity, and adiponectin levels were analyzed by analysis of covariance while controlling for confounding variables. Results:Haitian American participants were older (P = .032), had higher fasting plasma glucose (P = .036), and A1C (P = .016), but had lower levels of Hs-CRP (P < .001), insulin and HOMA2-IR and lower abdominal obesity (P = .030), than African Americans. Haitian Americans had significantly lower HOMA2-IR (P = .008) than African Americans when comparing both ethnicities with T2DM, high abdominal obesity, and adiponectin levels lower than the median ( Conclusion: The clinical significance of observed differences in insulin resistance, abdominal obesity, and adiponectin levels between Haitian Americans and African Americans could assist in forming public health policies that are ethnic specific.

Factors of Inflammation in Haitian Americans and African Americans with and without Type 2 Diabetes

Chronic low-grade inflammation has been implicated in the processes leading to the development of type 2 diabetes (T2D) and its progression. Non-Hispanic Blacks bear a disproportionate burden of T2D and are highly susceptible to inflammation. This cross-sectional study assessed and compared the serum levels of established adipocytokines; interleukin-6 (IL-6), C-reactive protein (CRP), leptin, and novel adipocytokines; chemerin and omentin in Haitian and African Americans with and without T2D. The relationships of these adipocytokines with metabolic syndrome (MetS), anthropometric and HOMA2 measures by ethnicity and diabetes status were also assessed. Serum levels of IL-6, CRP, leptin, chemerin and omentin were determined by the ELISA method. HOMA2 measures were calculated for insulin sensitivity (HOMA2-IS) and insulin resistance (HOMA2-IR). Analyses of available data for 230 Haitian Americans and 241 African Americans (240 with and 231 without T2D) for the first study showed that Haitian Americans with and without MetS had lower levels of IL-6 and CRP compared to African Americans with and without MetS (P Ethnic-specific diabetes intervention and treatment programs must be designed to target Haitian Americans and African Americans as separate unique groups, in order to reduce the burden of T2D among the non-Hispanic Black community. Further research is needed to gain better understanding of the role of inflammation and T2D in this population.

Prehistoric hand stencils at Fern Cave, North Queensland (Australia): environmental and chronological implications of Raman spectroscopy and FT-IR imaging results

Raman spectroscopy and FT-IR imaging analyses of cave wall pigment samples from north Queensland (Australia) indicate that some hand stencils were undertaken during a dry environmental phase indicating late Holocene age. Other, earlier painting episodes also took place during dry environmental periods of the terminal Pleistocene and/or early Holocene. These results represent a rare opportunity to attain chronological information for rock art in conditions where insufficient carbon is present for radiocarbon dating.

Characterization of electron trapping in dye-sensitized solar cells by near-IR transmittance measurements

In situ near-IR transmittance measurements have been used to characterize the density of trapped electrons in dye-sensitized solar cells (DSCs). Measurements have been made under a range experimental conditions including during open circuit photovoltage decay and during recording of the IV characteristic. The optical cross section of electrons at 940 nm was determined by relating the IR absorbance to the density of trapped electrons measured by charge extraction. The value, σn = 5.4 × 10-18 cm2, was used to compare the trapped electron densities in illuminated DSCs under open and short circuit conditions in order to quantify the difference in the quasi Fermi level, nEF. It was found that nEF for the cells studied was 250 meV over wide range of illuminat on intensities. IR transmittance measurements have also been used to quantify shifts in conduction band energy associated with dye adsorption.

QUT Digital Repository: Integrating the University’s IR with other digital collections

Queensland University of Technology’s Institutional Repository, QUT ePrints (http://eprints.qut.edu.au/), was established in 2003. With the help of an institutional mandate (endorsed in 2004) the repository now holds over 11,000 open access publications. The repository’s success is celebrated within the University and acknowledged nationally and internationally. QUT ePrints was built on GNU EPrints open source repository software (currently running v.3.1.3) and was originally configured to accommodate open access versions of the traditional range of research publications (journal articles, conference papers, books, book chapters and working papers). However, in 2009, the repository’s scope, content and systems were broadened and the ‘QUT Digital repository’ is now a service encompassing a range of digital collections, services and systems. For a work to be accepted in to the institutional repository, at least one of the authors/creators must have a current affiliation with QUT. However, the success of QUT ePrints in terms of its capacity to increase the visibility and accessibility of our researchers' scholarly works resulted in requests to accept digital collections of works which were out of scope. To address this need, a number of parallel digital collections have been developed. These collections include, OZcase, a collection of legal research materials and ‘The Sugar Industry Collection’; a digitsed collection of books and articles on sugar cane production and processing. Additionally, the Library has responded to requests from academics for a service to support the publication of new, and existing, peer reviewed open access journals. A project is currently underway to help a group of senior QUT academics publish a new international peer reviewed journal. The QUT Digital Repository website will be a portal for access to a range of resources to support copyright management. It is likely that it will provide an access point for the institution’s data repository. The data repository, provisionally named the ‘QUT Data Commons’, is currently a work-in-progress. The metadata for some QUT datasets will also be harvested by and discoverable via ‘Research Data Australia’, the dataset discovery service managed by the Australian National Data Service (ANDS). QUT Digital repository will integrate a range of technologies and services related to scholarly communication. This paper will discuss the development of the QUT Digital Repository, its strategic functions, the stakeholders involved and lessons learned.