Comparison of assessment techniques: plasma lipid and lipoproteins related to the metabolic syndrome

Review of Laboratory Methods to Determine HDL and LDL Subclasses and Their Clinical Importance

Given the high prevalence of cardiovascular disease, accurate identification of methods for assessing lipoprotein subclasses, mainly low-density lipoprotein (LDL) and high-density lipoprotein (HDL) subfractions, can play an essential role in predicting the incidence of cardiovascular disease such as heart attack. LDL and HDL subclasses differ in size, surface charge, lipid and protein compositions, and biological role. There is no "gold standard" method for measuring the LDL and HDL subclasses or standardizing the different methods used to measure their subfractions. Over the past decades, various techniques have been introduced to evaluate and measure subclasses of these two lipoproteins, each with its own advantages and disadvantages. Development of laboratory methods that accurately HDL and LDL function must be developed and validated to high-throughput for clinical usage. In this review study, we tried to examine different methods of evaluating various subclasses of LDL and HDL by mentioning the strengths and weaknesses of each.

Chitooligosaccharide induces mitochondrial biogenesis and increases exercise endurance through the activation of Sirt1 and AMPK in rats

By catabolizing glucose and lipids, mitochondria produce ATPs to meet energy demands. When the number and activity of mitochondria are not sufficient, the human body becomes easily fatigued due to the lack of ATP, thus the control of the quantity and function of mitochondria is important to optimize energy balance. By increasing mitochondrial capacity? it may be possible to enhance energy metabolism and improve exercise endurance. Here, through the screening of various functional food ingredients, we found that chitooligosaccharide (COS) is an effective inducer of mitochondrial biogenesis. In rodents, COS increased the mitochondrial content in skeletal muscle and enhanced exercise endurance. In cultured myocytes, the expression of major regulators of mitochondrial biogenesis and key components of mitochondrial electron transfer chain was increased upon COS treatment. COS-mediated induction of mitochondrial biogenesis was achieved in part by the activation of silent information regulator two ortholog 1 (Sirt1) and AMP-activated protein kinase (AMPK). Taken together, our data suggest that COS could act as an exercise mimetic by inducing mitochondrial biogenesis and enhancing exercise endurance through the activation of Sirt1 and AMPK.

Comparability of methods for LDL subfraction determination: A systematic review

Identifying and aggressively treating individuals at elevated risk of developing cardiovascular disease (CVD) is critical to optimizing health outcomes. The CVD risk factors defined by the National Cholesterol Education Program do not fully predict individuals at high risk of developing CVD. Validation of potential methodologies against a reference method is essential to the adoption of a potential new risk factor to improve risk prediction. Low-density lipoprotein (LDL) subfraction has been advanced as a potential additional CVD risk factor. Currently, there is no reference method for determining LDL subfractions or standardizing the different methods used to measure LDL subfractions. We conducted a systematic review to identify reports comparing two or more methods of measuring LDL subfractions. Nine articles were identified that separated and quantified LDL subfractions by at least two methods. Comparative data were available for nuclear magnetic resonance vs. gel electrophoresis (GE), LipoPrint vs. other GE methods, ultracentrifugation vs. GE, and high performance gel filtration chromatography vs. GE. We found a wide range of agreement (from 7 to 94% concordance for classifying LDL patterns) among methods for LDL subfraction determinations. Different criteria and definitions were used among the articles to classify individuals with respect to CVD risk. No study used CVD or other clinical outcomes as an outcome measure. In summary, the currently available literature does not provide adequate data about comparability in terms of test performance to choose one or another method to serve as a standard nor are data on comparability in terms of predicting CVD outcomes.

Large artery stiffening with weight gain in humans: role of visceral fat accumulation

We tested the hypothesis that weight gain would increase arterial stiffness in healthy nonobese adults. To address this, we overfed 14 nonobese men (age: 23+/-1 years) approximately 1000 kcal/d for 6 to 8 weeks until a 5-kg weight gain was achieved. Carotid diameters (high-resolution ultrasound) and pressures (applanation tonometry), body composition (dual energy x-ray absorptiometry), and abdominal fat distribution (computed tomography) were measured at baseline and following 4 weeks of weight stability at each individual's elevated body weight. Overfeeding increased body weight 5.1+/-0.1 kg and body fat 3.4+/-0.4 kg (both P<0.001) in 45+/-7 days. Total abdominal fat increased 46+/-7 cm(2) with weight gain due to increases in both subcutaneous (30+/-6 cm(2)) and visceral fat (15+/-4 cm(2); all P<0.01). As hypothesized, weight gain increased arterial stiffness 13+/-6% and decreased arterial compliance 21+/-4% (both P<0.05). Furthermore, those individuals above the median increase in abdominal visceral fat demonstrated a significantly greater increase in arterial stiffness (0.97+/-0.29 versus 0.06+/-0.36 U; P<0.05) compared with those below the median. Consistent with these observations, the only correlates of the changes in arterial stiffness with weight gain were the increases in total abdominal fat (r=0.794), abdominal visceral fat (r=0.651), and waist circumference (r=0.470; all P<0.05). Taken together, these findings suggest that modest weight gain is associated with increases arterial stiffness in nonobese men. The degree of large artery stiffening with weight gain seems to be determined, in part, by the amount of abdominal visceral fat gain. Importantly, this relation is independent of the amount of total body fat gained.

Statistical Correlation and Projection Methods for Improved Information Recovery from Diffusion-Edited NMR Spectra of Biological Samples

Although NMR spectroscopic techniques coupled with multivariate statistics can yield much useful information for classifying biological samples based on metabolic profiles, biomarker identification remains a time-consuming and complex procedure involving separation methods, two-dimensional NMR, and other spectroscopic tools. We present a new approach to aid complex biomixture analysis that combines diffusion ordered (DO) NMR spectroscopy with statistical total correlation spectroscopy (STOCSY) and demonstrate its application in the characterization of urinary biomarkers and enhanced information recovery from plasma NMR spectra. This method relies on calculation and display of the covariance of signal intensities from the various nuclei on the same molecule across a series of spectra collected under different pulsed field gradient conditions that differentially attenuate the signal intensities according to translational molecular diffusion rates. We term this statistical diffusion-ordered spectroscopy (S-DOSY). We also have developed a new visualization tool in which the apparent diffusion coefficients from DO spectra are projected onto a 1D NMR spectrum (diffusion-ordered projection spectroscopy, DOPY). Both methods either alone or in combination have the potential for general applications to any complex mixture analysis where the sample contains compounds with a range of diffusion coefficients.

Low-density lipoprotein cholesterol estimation by the Anandaraja's formula--confirmation

The number of the indirect methods for LDL-C estimation is growing. Our result support the reliability of new Anandaraja's formula for low-density lipoprotein estimation from total cholesterol and triglycerides.