Focusing on High-Density Lipoprotein for Coronary Heart Disease Risk Reduction

Dysmetabolic signals in "metabolically healthy" obesity

SUMMARY

BACKGROUND

Obesity is associated with decreased insulin sensitivity, atherogenic dyslipidemia and hypertension, but clinical studies have also identified a "metabolically healthy" obese phenotype.

OBJECTIVE

To compare the characteristics of so-called "metabolically healthy" obese (MHO), normal weight subjects (MHNW) and obese with insulin resistance in the United States National Health and Nutrition Examination Survey, 1999-2004 (NHANES).

DESIGN, SETTING AND PARTICIPANTS

Insulin resistance was defined by a homeostatic model assessment (HOMA) value in the upper tertile for the entire NHANES cohort. "Metabolic health" was defined as the absence of diabetes, insulin resistance, metabolic syndrome, and lipid-lowering therapy. The study evaluated the 314 MHO, 1173 MHNW and 843 insulin-resistant obese from among the 6485 non-diabetic, non-pregnant adults aged 20-79 years.

MAIN OUTCOME MEASURES

Demographic, metabolic, nutrition and physical activity features.

RESULTS

MHO and MHNW groups were similar regarding age, and fasting glucose and triglyceride levels. MHO had higher insulin (P < 0.0001), insulin resistance as measured with the homeostatic model (P < 0.0001), non-HDL cholesterol (P = 0.002 in females and P = 0.049 in males) and C-reactive protein levels (P < 0.0001 in females and P = 0.038 in males), and lower high-density lipoprotein cholesterol (HDL) levels (P < 0.002). In addition, MHO females had higher low-density lipoprotein (LDL) cholesterol levels (P = 0.012) and systolic blood pressure (P = 0.02), and lower intake of dietary fiber (P = 0.0009) and levels of physical activity (P = 0.002). Triglycerides levels were normal in the MHO group.

CONCLUSIONS

"Metabolically healthy" obese people have multiple dysmetabolic changes that may signal increased risk for coronary artery disease.

Diabetes and the metabolic syndrome: possibilities of a new breath test in a dolphin model

Diabetes type-2 and the metabolic syndrome are prevalent in epidemic proportions and result in significant co-morbid disease. Limitations in understanding of dietary effects and cholesterol metabolism exist. Current methods to assess diabetes are essential, though many are invasive; for example, blood glucose and lipid monitoring require regular finger sticks and blood draws. A novel method to study these diseases may be non-invasive breath testing of exhaled compounds. Currently, acetone and lipid peroxidation products have been seen in small scale studies, though other compounds may be significant. As Atlantic bottlenose dolphins (Tursiops truncatus) have been proposed as a good model for human diabetes, applications of dietary manipulations and breath testing in this population may shed important light on how to design human clinical studies. In addition, ongoing studies indicate that breath testing in dolphins is feasible, humane, and yields relevant metabolites. By studying the metabolic and cholesterol responses of dolphins to dietary modifications, researchers may gain insight into human diabetes, improve the design of costly human clinical trials, and potentially discover biomarkers for non-invasive breath monitoring.

Oxidized high-density lipoprotein is associated with increased plasma glucose in non-diabetic dyslipidemic subjects

BACKGROUND

Oxidized high-density lipoprotein (oxHDL) has reduced capacity for cholesterol efflux and some of other anti-atherogenic properties of HDL, but the role of oxHDL in the pathogenesis of cardiometabolic disease has not been fully demonstrated. This study investigated the association of oxHDL with plasma glucose (PG) and the other atherosclerotic risk variables in non-diabetic dyslipidemic subjects.

METHODS

Conventional atherosclerotic markers and LDL particle size (LDL-PS), as determined by gel electrophoresis, were measured in 155 non-diabetic subjects (mean age of 57 years) with dyslipidemia. Serum oxHDL levels were quantified using an antibody against oxidized human apoA-I in a sandwich ELISA format.

RESULTS

Multiple regression analysis adjusted for possible confounders revealed that HDL-cholesterol was independently, significantly and positively correlated with LDL-PS and oxHDL. By multiple regression analysis, oxHDL was independently, significantly and positively correlated with fasting PG (β=0.19, P=0.01). Subjects in the highest PG tertile group had approximately 30% higher oxHDL levels than the lowest PG tertile group.

CONCLUSIONS

These results suggest that high PG levels may contribute to the HDL oxidation, irrespective of HDL-cholesterol levels, even in non-diabetic subjects with dyslipidemia, and that the measurement of oxHDL may be a useful marker of dysfunctional HDL.