The presence of elevated circulating triacylglycerol (TG)-rich very low density lipoprotein (VLDL) and apolipoprotein B-100 (apoB-100) levels represents an independent risk factor for coronary artery disease. Triacylglycerol hydrolase catalyzes the mobilization of cytoplasmic TG stores. To test the hypothesis that the enzyme plays a role in the provision of core lipids for the assembly of VLDL, we inhibited the lipase activity in primary rat hepatocytes and analyzed lipid and apoB synthesis and secretion. Inhibition of lipolysis resulted in a dramatic decrease in secretion of TGs. In addition, secretion of cholesteryl ester and phosphatidylcholine was substantially decreased. Analysis of secreted apolipoproteins indicated that apoB-100 secretion was much more sensitive to lipase inhibition than was apoB-48 secretion, perhaps because of the ability of apoB-48 to be secreted as a relatively lipid-poor particle. The results agreed with those obtained with hepatoma cells transfected with triacylglycerol hydrolase cDNA, in which preferential lipidation of apoB-100 was observed. Together, our findings provide evidence that inhibition of intracellular TG hydrolysis significantly decreases apoB-100 secretion and suggest that triacylglycerol hydrolase may be a suitable pharmacological target in efforts to lower plasma lipid levels.

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Our data suggest use of the Worthley et al. formula Osm = 2[Na +]+glucose+BUN for rapid mental calculation and the formulas of Bhagat et al. or ours for calculation of serum osmolality by equipment linked to a computer.

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The results indicate that the apoB/apoAI ratio, apoB and Lp(a) are independent risk factors for CAD and are superior to any of the cholesterol ratios. We suggest using the apoB/apoAI ratio as the best marker of CAD in clinical practice.

The associations of serum calcium and phosphorus concentrations as well as other cardiovascular risk factors were investigated in relation to the existence and severity of coronary heart disease (CHD) in 260 clinically stable, angiographically defined CHD patients aged 40-70 years. The subjects were classified as CHD(+) cases if one or more coronary arteries had a significant stenosis (> or =70%) and CHD(-) controls if there was no stenosis (< or =10%) in any artery. The severity of coronary occlusion was scored on the basis of the number and extent of lesions, as normal, mild, moderate or severe. Fasting serum concentrations of electrolytes, lipids and (apo)lipoproteins were determined. The concentrations of serum total calcium (2.41 +/-0.14 vs. 2.33 +/- 0.22 mmol/L, p < or = 0.05), albumin-corrected calcium (2.33 +/- 0.25 vs. 2.23 +/- 0.25 mmol/L, p < or = 0.01), phosphorus (1.32 +/-0.21 vs. 1.25 +/- 0.17 mmol/L, p < or = 0.007) and the ion product of calcium and phosphorus (3.16 +/- 0.58 vs. 2.91 +/- 0.50, p < or =0.0001) were significantly higher in the CHD(+) compared to the CHD(-) group. Patients with CHD compared with controls had increased serum levels of triglyceride, total cholesterol, low-density lipoprotein-cholesterol (LDL-C), apolipoprotein B (apoB), lipoprotein(a) [Lp(a)] and decreased serum levels of high-density lipoprotein (HDL)-C and apoAI. Multiple logistic regression analysis showed strong and significant association between diabetes mellitus (odds ratio, OR = 5.24, p < or = 0.0001), male gender (OR = 8.84, p < or =0.0001), Lp(a) (OR = 1.014, p < or =0.006), hypertension (OR = 2.61, p < or =0.02), apoB (OR = 1.031, p < or =0.001), age (OR = 1.055, p < or =0.003), phosphorus (OR = 2.438, p < or =0.01), albumin-adjusted calcium (OR = 1.532, p < or =0.05), cholesterol (OR = 1.009, p < or =0.05) and the occurrence of CHD. On the basis of bivariate correlation analysis, serum-adjusted calcium was positively correlated with the levels of cholesterol (r = 0.285, p < or =0.0001), LDL-C (r = 0.320, p < or =0.0001), Lp(a) (r = 0.173, p < or = 0.005), apoB (r = 0.237, p < or =0.0001), LDL-C/apoB ratio (r = 0.180, p < or= 0.007), apoAI (r = 0.181, p < or =0.003) and inversely to HDL-C (r = -0.146, p < or =0.02) and HDL-C/apoAI ratio (r = -0.263, p < or =0.0001). Serum phosphorus concentration was a significant correlate of triglyceride (r = 0.199, p < or =0.001) and Lp(a) (r = 0.129, p < or =0.04). The results demonstrated that serum calcium and phosphorus are associated with the prevalence and severity of CHD, probably through correlation with atherogenic lipids and (apo)lipoproteins. Serum calcium and phosphorus and their ion product were also independent risk factors for CHD.

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