For 26 months, we fed 60 baboons a high saturated fat, high cholesterol diet that contained very low concentrations of four common pesticides (chlordane, parathlon, dlazlnon, and carbofuran). We detected no effect of pesticides on body weight, serum llpld, or Iipoprotein cholesterol concentrations, or experimental atherosclerosis. We then examined the associations of serum llpld and Iipoprotein cholesterol concentrations {predictor variables) with arterial lesions (naponto variables). Among predictor variables, very low density Iipoprotein plus low density Iipoprotein cholesterol concentration showed a positive association with fatty streaks in the aorta and its ma|or branches, Including the coronary arteries, while high density Iipoprotein cholesterol concentration showed a consistently negative association. The very low density Iipoprotein plus low density llpoproteln/hlgh density Iipoprotein cholesterol ratio was more highly associated with lesions than was either value alone. These results are consistent with epidemlologic evidence suggesting that high density Iipoprotein cholesterol concentration Is Inversely related to probability of developing clinically manifest atherosclerotic disease. (Arteriosclerosis 1:3-12, January/February 1981)
A B S TRA CT The serum lipoproteins of five patients with abetalipoproteinemia (ABL) were separated by ultracentrifugation and then analyzed either intact or after delipidation. In accord with previous findings, all of the patients lacked serum particles with the characteristics of normal low-density lipoproteins (LDL) and of the LDL apoprotein as assessed by immunochemical methods. Each patient exhibited on every examination an abnormal particle, "LDL", which had the fotational properties of LDL, the polypeptide makeup of highdensity lipoproteins HDL, the spectral and morphological characteristics of neither LDL nor HDL, and a relatively low content of cholesteryl esters. The HDL were abnormal in having a marked decrease in their total plasma content, an altered proportion of the subclasses HDL2 and HDLa, and a peculiar polypeptide distribution, comprising both normal and additional components, usually not seen in normal controls. The patients also exhibited a decrease of plasma lecithin-cholesterol acyl transferase (LCAT) activity which probably accounted for the low content of cholesteryl esters in both "LDL" and HDL, and in turn for the unusual appearance of "LDL" on electron microscopy.
A paramagnetic quenching reagent, Mn-2+/EDTA (1:2.2), was developed for the purpose of investigating the phospholipid phosphate groupings of human serum low and high density lipoproteins through the quenching effect of the reagent on the 31-P nuclear magnetic resonance signals from these complexes. Systems investigated included native low and high density serum liproteins (LDL, HDL2, and HDL3), egg phosphatidylcholine vesicles together with appropriate phosphodiester model systems, diethyl phosphate in aqueous buffer, and phosphatidylcholine and sphingomyelin both in anhydrous methanol. The results of these studies indicated that ca. 50 percent of the phospholipid-phosphorus signal of LDL is quenched upon titration as compared to an 80-85 percent figure observed for HDL2 and HDL3. In all cases the spectral effects were totally reversible upon removalof the paramagnetic ion by dialysis. The results of the titration studies indicated a similar but not an identical behavior between HDL2 and HDL3. The results are consistent with model structures of HDL and LDL particles derived from low angle X-ray diffraction.
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