Leptin and clustering of the components of risk factors for metabolic syndrome / 中华预防医学杂志

<p><b>OBJECTIVES</b>To evaluate relationship between serum level of leptin and the components of risk factors for metabolic syndrome and to analyze the characteristics and laws of clustering of the risk factors.</p><p><b>METHODS</b>Totally, 795 non-diabetic adult Chinese subjects (691 men and 104 women, aged 40 - 75 years) from a diabetes prevalence survey in 2000 were involved in this study. Measurements included serum levels of true insulin (TI), leptin, fasting lipids, fasting glucose (FBG) and 2 h postchallenge glucose, as well as seated blood pressure (BP), body mass index (BMI), ratio of waist circumference to hip circumference (WHR), calculated quantitative insulin sensitivity check index (QUICKI), etc. Relationship between serum level of leptin and all the variables mentioned above was studied by statistical methods such as factor analysis, etc.</p><p><b>RESULTS</b>Serum level of leptin in the study subjects increased with the number of components of abnormal metabolism they had. Detection rates of obesity, hypertension, dyslipidemia and metabolic syndrome were significantly higher in those with the upper tertile of serum leptin level than in those with the lower tertile. Factor analysis revealed that variation of the 11 variables including serum level of leptin was affected by the three factors, i.e., the central factor associated with BMI, WHR, FTI, QUICKI and higher serum level of triglyceride (TG) and lower serum level of high-density lipoprotein-cholesterol (HDL-C), the glucose intolerance factor loaded with blood glucose level, FTI, QUICKI and higher serum level of TG (in women only) and the hypertension factor loaded with blood pressure and BMI (in men only), which could explain 62.0% and 66.7% of total variance in men and women, respectively, and higher serum level of TI and insulin resistance also loaded with both the central factor and glucose tolerance factor.</p><p><b>CONCLUSIONS</b>Serum level of leptin was significantly associated with the key markers of metabolic syndrome. Hyperleptinaemia could be a new component of metabolic syndrome. Clustering of the risk factors for metabolic syndrome could be affected by many factors, and although insulin resistance played an important role in it, insulin resistance alone could not explain its etiology.</p>

Precision of rat BMD measurements by dual-energy X-ray absorptiometry in vitro / 中国医学科学院学报

<p><b>OBJECTIVE</b>To evaluate the precision of rat bone mineral density (BMD) measurements by Norland Excellplus dual-energy X-ray absorptiometry (DXA) and to investigate the BMD changes in ovariectomized (Ovx) rats in vitro.</p><p><b>METHODS</b>(1) The coefficients of variation (CV) for BMD measurements at various skeletal regions were repeatedly determined by DXA in 10 Wistar rats in vitro. (2) BMD in lumbar vertebra (L5) and both sides of femurs was measured in total 90 rats. And (3) changes in BMD between Ovx and sham rats were compared.</p><p><b>RESULTS</b>(1) The short-term CVs of BMD measurements in different regions by DXA were as follows, 1.58% for lumbar vertebra (L5), 0.90% for left femur, and 0.86% for right femur, respectively. The long-term CVs were 2.22% for lumbar vertebra (L5), 1.09% for left femur, and 1.20% for right femur. (2) The BMD values in 90 Wistar rats were (127.5 +/- 12.3) in lumbar vertebra (L5), (82.6 +/- 11.3) in corpus vertebra (L5'), (150.7 +/- 10.6) in left femur and (149.9 +/- 10.6) mg/cm2 in right femur, respectively. The correlation coefficient of BMD measurements between left and right femurs was 0.792 (P < 0.001). (3) In Ovx group, the BMD values of corpus vertebra (L5') and distal femurs were significantly decreased, that was 10.0%-17.5% lower in comparison with sham group (P < 0.001).</p><p><b>CONCLUSIONS</b>Measurement of rat BMD in vitro by Norland Excellplus DXA is a useful method, and it can reflect the changes in rat bone masses with good precision.</p>