The authors estimated abdominal fat distribution on the basis of measurements at computed tomography (CT). The attenuation range for fat tissue was defined as the interval within the mean plus or minus 2 SDs considered to be individual variation. Fat areas found with this method were closely correlated with those obtained by means of the computed planimetric method or with a fixed attenuation range from -190 to -30 HU as the standard of reference. Although the average CT numbers obtained with different scanners were distributed widely, the calculated fat areas were almost identical. This method might be a practical and standardized method at CT.
It is well known that obesity is frequently associated with low levels of serum high-density lipoprotein (HDL) cholesterol. However, the mechanism for this reduction has not been fully clarified. Cholesteryl ester transfer protein (CETP) transfers cholesteryl ester from HDL to apolipoprotein B-containing lipoproteins and plays an important role in regulating the concentration and composition of HDL. To elucidate the mechanism for the reduction of serum HDL cholesterol in obesity, we analyzed serum lipoproteins, CETP, and postheparin lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL) activities in 30 obese subjects (17 women and 13 men, age 44±14 years, mean±SD). We also investigated the relationship between these variables, total adiposity, and indices of body fat distribution. The average body mass index of the obese subjects was 33.1±4.8 kg/m 2 (range, 26.4 to 43.8 kg/m 2 ). The obese subjects showed significantly lower serum HDL cholesterol levels than control subjects (1.04±0.28 versus 1.50±0.34 mmol/L, P<.01). In the obese subjects, both activities and protein mass of CETP and postheparin HTGL activities were significantly increased, whereas postheparin I t is well known that obese patients are often associated with low serum high-density lipoprotein (HDL) cholesterol levels. 1 Although some studies suggest that low HDL cholesterol in obesity might be a risk factor for coronary heart disease (CHD), 2 -3 few data show that low HDL cholesterol in obesity directly caused or was closely associated with the occurrence and development of CHD. Recent studies have shown that the degree of body fat distribution was more important for the occurrence of complications, particularly CHD, than body fat accumulation.4 -8 Therefore, it appears necessary to clarify the mechanism and pathophysiological significance of low serum HDL cholesterol levels in obesity.Cholesteryl ester transfer protein (CETP) is a plasma glycoprotein that transfers cholesteryl ester (CE) from HDL to apolipoprotein (apo) B-containing lipopro- 9 and is one of the major determinants of plasma HDL cholesterol levels. 10 In Japan, some laboratories, including ours, reported that some types of familial hyperalphalipoproteinemia are associated with a genetic deficiency of plasma CETP. 1014 Our studies have shown that lipoprotein abnormalities in CETP-deficient patients are characterized by the presence of polydisperse low-density lipoprotein (LDL) 1112 and a marked elevation of HDL cholesterol.13 ' 14 These results indicate that CETP plays an important role in modulating both the quality and quantity of plasma lipoproteins. Plasma CETP is synthesized by the liver, small intestine, spleen, adrenal gland, and adipose tissues. In particular, Jiang et al 15 reported that adipose tissue is one of the major sites of CETP synthesis in mammals.Lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL) are known to regulate HDL cholesterol levels. 1617 We reported that postheparin plasma LPL activity was positively correlated with s...
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