Use of 3H-cholesteryl linoleyl ether as a quantitative marker for loss of cholesteryl ester during regression of cholesterol-induced aortic atheromas in rabbits

Reverse cholesterol transport in mice expressing simian cholesteryl ester transfer protein

The role of cholesteryl ester transfer protein (CETP) in atherogenesis remains ambiguous, as both pro and antiatherogenic effects have been described. Expression of CETP increases HDL-cholesteryl ester turnover, but there is no direct evidence whether CETP mobilizes cholesterol in vivo. The rate of cholesterol removal injected into a leg muscle as cationized low density lipoprotein (cat-LDL) was compared in CETP transgenic and control mice. Four days after injection the exogenous cholesterol mass retained in muscle was 65% in CETP transgenic and 70% of injected dose in controls; it decreased to 52-54% by day 8 and negligible amounts remained on day 28. The cat-LDL was labeled with either 3H-cholesterol oleate (3H-CE) or 3H-cholesteryl oleoyl ether (3H-COE), a nonhydrolyzable analog of 3H-CE. After injection of 3H-CE cat-LDL, clearance of 3H-cholesterol had a t(1/2) of 4 days between day 4 and 8 but there was little loss of 3H-COE between day 4 and 51. Liver radioactivity on day 4 was 1.7% in controls and 3.4% in CETP transgenics; it was 2.8 and 4.6%, respectively, on day 8. 3H-COE in liver accounted for 60% of label in CETP transgenics. In conclusion, high levels of plasma CETP in mice do not enhance reverse cholesterol transport in vivo but may act on extracellularly located cholesteryl ester.

Does therapeutic intervention achieve slowing of progression or bona fide regression of atherosclerotic lesions?

-This review focuses on the regression of atherosclerosis in humans and experimental animals. It highlights the difficulties to determine unequivocally whether with a given therapeutic intervention, such as diet, drugs, or apheresis, the progression of lesions was curtailed or bona fide regression of atherosclerotic lesions was achieved. It seems appropriate to mention that 2 very different ways to measure regression were used in experimental animals and in humans. Regression in animals was determined mainly in the aorta or coronary arteries isolated at post mortem, and the criteria used were degree of sudanophilia and/or aortic wall thickness and cellular composition or cholesterol content. In humans, the evaluation of regression relied mainly on quantitative coronary angiography. The literature of the past decade is reviewed selectively but not exhaustively, and in some instances, a brief historical overview is given.

Treatment of hypercholesterolemia in children and adolescents

In patients with severe genetic hypercholesterolemia, therapeutic reduction of elevated serum total cholesterol and LDL cholesterol should begin in early childhood to lower the risks of cardiovascular disease later in life. We evaluated the effects of outpatient therapy with diet alone and with combined diet and drug therapy in children and adolescents with hypercholesterolemia of apparent dominant inheritance. Serum lipid values before and during dietary treatment were available in 35 patients (mean age at start of treatment 7.9 years, range 2.0-17.6 years) followed for an average duration of 17.5 months (range 4-70 months). A comparison between untreated state and combined therapy with diet and cholestyramine was possible in 14 patients (mean age 8.6 years, range 2.4-17.0 years) followed for 27.9 months (range 4-97 months). Dietary modification achieved by repeated counseling and training lowered serum total cholesterol by mean (+/- SE) 11.7 +/- 1.9% (p < 0.0001) and LDL cholesterol by 17.3 +/- 3.5% (p < 0.0001). However, five of 35 patients did not show an appreciable effect of therapy (cholesterol reduction < 5%), possibly because of non-compliance. Diet combined with cholestyramine in an average dose of 0.36 g/kg body weight/day reduced total cholesterol by 33.0 +/- 2.4% (p < 0.0001) and LDL cholesterol by 37.5 +/- 4.3% (p < 0.0001) and was effective in all patients. Both forms of treatment had no effect on serum triglycerides and HLD cholesterol. No serious side effects were noted, and percentile values for weight and height remained unchanged in all but three obese children.(ABSTRACT TRUNCATED AT 250 WORDS)

Removal of cholesteryl ester from hepatic reticuloendothelial cells in vivo is not enhanced by plasma cholesteryl ester transfer protein

The putative role of cholesteryl ester transfer protein (CETP) in the removal of cholesteryl ester from hepatic reticuloendothelial cells in vivo was studied in hamsters. The parameter tested was retention of [3H]cholesteryl linoleyl ether ([3H]CLE), a nonhydrolysable analog of cholesteryl ester, in the liver after injection of [3H]CLE labeled acetylated LDL, which is targetted to nonparenchymatous littoral cells. In hamsters fed laboratory chow, plasma cholesteryl ester transfer activity (CETA) was 10.6 +/- 0.9 units and the retention of [3H]CLE in the liver 28 days after injection was 86% of the 4 h value. It was about 55% in rats fed the same diet, in which CETA was not detectable. When the diet was supplemented with 2% cholesterol and 15% margarine, CETA activity in hamsters increased 2-fold, yet no change in retention of [3H]CLE in liver was seen after 28 days. In rats, the retention of [3H]CLE in the liver was also not changed by the dietary fat supplementation. These results do not support the role of CETP in vivo in removal of cholesteryl ester from intact reticuloendothelial cells.