Effect of time of administration on cholesterol-lowering by psyllium: a randomized cross-over study in normocholesterolemic or slightly hypercholesterolemic subjects

BACKGROUND: Reports of the use of psyllium, largely in hypercholesterolemic men, have suggested that it lowers serum cholesterol as a result of the binding of bile acids in the intestinal lumen. Widespread advertisements have claimed an association between the use of soluble fibre from psyllium seed husk and a reduced risk of coronary heart disease. Given the purported mechanism of cholesterol-lowering by psyllium, we hypothesized that there would be a greater effect when psyllium is taken with breakfast than when taken at bedtime. Secondarily, we expected to confirm a cholesterol-lowering effect of psyllium in subjects with "average" cholesterol levels. METHODS: Sixteen men and 47 women ranging in age from 18 to 77 years [mean 53 +/- 13] with LDL cholesterol levels that were normal or slightly elevated but acceptable for subjects at low risk of coronary artery disease were recruited from general gastroenterology and low risk lipid clinics. Following a one month dietary stabilization period, they received an average daily dose of 12.7 g of psyllium hydrophilic mucilloid, in randomized order, for 8 weeks in the morning and 8 weeks in the evening. Change from baseline was determined for serum total cholesterol, LDL, HDL and triglycerides. RESULTS: Total cholesterol for the "AM first" group at baseline, 8 and 16 weeks was 5.76, 5.77 and 5.80 mmol/L and for the "PM first" group the corresponding values were 5.47, 5.61 and 5.57 mmol/L. No effect on any lipid parameter was demonstrated for the group as a whole or in any sub-group analysis. CONCLUSION: The timing of psyllium administration had no effect on cholesterol-lowering and, in fact, no cholesterol-lowering was observed. Conclusions regarding the effectiveness of psyllium for the prevention of heart disease in the population at large may be premature

Radioimmunoassay of apolipoprotein A-i. application of a non-ionic detergent (Tween-20) and solid-phase staphylococcus

[[abstract]]We describe two techniques for radioimmunoassay of apolipoprotein A-I (apoA-I) in human plasma, each involving use of a non-ionic detergent, Tween-20, to expose antigenic sites, and one involving "IgG SORB" (a suspension of killed staphylococci) as a solid-phase separator. Tween-20 (3.75 g/L) decreased nonspecific binding and unmasked the antigenic sites on the apoA-I molecule in plasma to the same extent as did a tedious delipidation procedure, without altering the binding affinity between apoA-I and apoA-I antibodies as determined by Scatchard analysis (Ka congruent to 2.83 X 10(8) L/mol). The widely accepted double-antibody immunoprecipitation technique for separating bound and unbound 125I-labeled apoA-I is time-consuming, owing to extended periods of incubation and centrifugation IgG SORB effectively separates bound from unbound 125I-labeled apoA-I and the reaction is complete within 10 min. On comparing concentrations of apoA-I in human plasma by the conventional second-antibody (y) and solid-phase IgG SORB methods (x), we found results by the two techniques to be reasonably identical (r = 0.98, y = 1.2x -- 0.17). The mean concentrations of apoA-I in plasma from 65 normal and five hyperlipidemic patients were 1.33 (SD 0.32) and 0.78 (SD 0.35) g/L, respectively, and apoA-I and high-density lipoprotein cholesterol were significantly correlated (r = 0.72, p less than 0.001)

Apolipoprotein A-I as a marker of angiographically assessed coronary-artery disease

[[abstract]]This study was designed to determine whether the plasma level of apolipoprotein A-I is a better discriminator of angiographically documented coronary-artery disease than the level of high-density-lipoprotein (HDL) cholesterol in male subjects. The level of plasma apolipoprotein A-I in 83 patients with coronary-artery disease was 96.7 +/- 4.2 mg per deciliter (mean +/- S.E.M.), which was significantly lower (P less than 0.0001) than the level in 25 patients without coronary-artery disease (146.9 +/- 2.1 mg per deciliter). The levels of HDL cholesterol were also lower (P less than 0.0001) in patients with coronary-artery disease (31.9 +/- 1.5 mg per deciliter) than in those without it (45.9 +/- 2.3 mg per deciliter). A stepwise discriminant analysis, however, indicated the superiority of apolipoprotein A-I over HDL cholesterol in detecting coronary-artery disease. Furthermore, a linear discriminant analysis suggested that although HDL cholesterol by itself was a discriminator of coronary-artery disease, it did not provide a substantial increase in discriminatory value over that provided by apolipoprotein A-I; in contrast, apolipoprotein A-I levels added discriminatory value to the information obtained by measuring HDL cholesterol alone. We conclude that apolipoprotein A-I by itself is more useful than HDL cholesterol for identifying patients with coronary-artery disease