Thyroid hormone and thyrotropin levels in patients placed on colestipol hydrochloride.

Bile acid sequestrant resins can bind T4 in vitro and in the gut. Therefore, the effect of colestipol HCl on thyroid function was studied prospectively in 17 subjects with type II hyperlipoproteinemia. Serum T4, T3, T3 resin uptake, and TSH levels were measured before and during therapy.

Apolipoprotein A-II content of human plasma high density lipoproteins measured by radioimmunoassay.

A double antibody radioimmunoassay for human ApoA-II is reported. ApoA-II isolated from human plasma high density lipoprotein (HDL) by column chromatography migrated as a single band on polyacrylamide disc gel electrophoresis, had the appropriate amino acid composition, and provoked the production of monospecific antisera. (125)I-ApoA-II (iodinated by lactoperoxidase, purified by Sephadex G-75 chromatography) migrated with "cold" ApoA-II as a single band on disc gel electrophoresis in SDS.

Plasma triglyceride lowering by exercise despite increased food intake in patients with type IV hyperlipoproteinemia.

Exercise can lower fasting triglyceride levels (TG). This study was undertaken to determine whether the exercise-induced decrease in TG is the result of a negative caloric balance. Five subjects with primary type IV hyperlipoproteinemia were given diets comparable in composition to their usual diets.

The effects of colestipol on the metabolism of very-low-density lipoproteins in man.

Bile acid-binding resins, currently used for the treatment of Type II hyperlipoproteinemia, decrease LDL cholesterol by 25 to 35 per cent. Elevations of plasma triglycerides sometimes occur with resin therapy, suggesting that alterations in metabolism may not be confined solely to LDL. To characterize the effects of the resins on lipoproteins in greater detail, we carried out two studies using colestipol.

Structure of high density lipoprotein. The immunologic reactivities of the COOH- and NH2-terminal regions of apolipoprotein A-I.

Only 5 to 10% of the apolipoprotein A-I (ApoA-I) of intact high density lipoprotein (HDL) is detectable by radioimmunoassay. In addition, when isolated ApoA-I is recombined with lipids in vitro, its immunologic reactivity is decreased by 30 to 95%. Thus, ApoA-I is less reactive immunologically in the presence of lipids.

Alterations in levels and interrelations of plasma apolipoproteins induced by diet.

Diets high in carbohydrates increase the rates of hepatic secretion of VLDL in man. VLDL particles are secreted in greater numbers; they also tend to contain more triglycerides and to be larger in size. Comparable changes in intestinal secretion of chylomicrons and VLDL accompany fat absorption.

Measurement of apolipoprotein A-I in rat high density lipoprotein and in rat plasma by radioimmunoassay.

A double antibody radioimmunoassay (RIA) for rat apolipoprotein A-I is reported. The ApoA-I isolated from delipidated HDL by gel filtration yielded a single band on polyacrylamide gel electrophoresis in sodium dodecyl sulfate (SDS), and its amino acid composition resembled that reported by others. ApoA-I was iodinated by lactoperoxidase and the resulting 125I-apoA-I was purified by gel filtration.

Structure of human high density lipoprotein reassembled in vitro. Radioimmunoassay studies.

Immunologic approaches to studying lipoprotein structure have been limited because the methods have not been quantitative enough. Recently we reported (Schonfeld, G., and Pfleger, B.

Apolipoproteins in human pregnancy.

Apolipoproteins are important in the structure and metabolism of lipoproteins, and alterations in levels of apoproteins or in their interrelations occur in some forms of hyperlipemia. Pregnancy is regularly accompanied by hyperlipoproteinemia, but while data on lipoprotein lipids is available, the apopipoproteins have not been studied. To characterize the lipemia of pregnancy more completely, we studied some of the apolipoproteins in plasmas of pregnancy women.

Characterization of the plasma lipoproteins of the genetically obese hyperlipoproteinemic Zucker fatty rat.

The plasma lipoproteins of the Zucker fatty rat were characterized with respect to lipid and apoprotein composition, and results were compared with those obtained from lean controls. Information on apoproteins was obtained from gel filtration experiments and electrophoresis on polyacrylamide gels. Very low density lipoproteins (VLDL) were increased several-fold in fatties, and 78% of their mass was triglycerides compared with 60% in the controls.

The structure of human high density lipoprotein and the levels of apolipoprotein A-I in plasma as determined by radioimmunoassay.

The major apoprotein of high density lipoprotein is apolipoprotein A-I (ApoA-I). In addition to being a structural component of this class of lipoproteins, ApoA-I also has a physiologic role as an activator of lecithin-cholesterol acyl transferase, an enzyme important in the metabolism of all lipoproteins. To measure ApoA-I content in human plasma, to assess its immunologic activity in hyperlipoproteinemia, and to carry out certain structural studies of high density lipoproteins, we have developed a double antibody radioimmunoassay.

Assay of total plasma apolipoprotein B concentration in human subjects.

We have developed a double antibody radioimmunoassay (RIA) for human apolipoprotein B (ApoB). The assay measures not only the ApoB content of beta-lipoproteins (low density lipoproteins [LDL]) but also that contained in the other lipoproteins in plasma. Purified lymph and plasma chylomicrons and plasma very low density lipoproteins (VLDL) produced displacement curves in the assay system which paralleled those produced by pure LDL.

Utilization of exogenous free fatty acids for the production of very low density lipoprotein triglyceride by livers of carbohydrate-fed rats.

High carbohydrate diets enhance the hepatic output of very low density lipoprotein triglycerides. The fatty acids of these triglycerides could come from exogenous sources (i.e.