Supplementation of test meals with fat-free phytosterol products can reduce cholesterol micellarization during simulated digestion and cholesterol accumulation by Caco-2 cells.

Phytosterols have been shown to reduce cholesterol absorption in humans. Supplementing phytosterols in fat-free formulations, however, has yielded controversial results. In the present study, we investigated the effect of supplementing test meals with different fat-free phytosterol products on cholesterol incorporation into mixed micelles during simulated digestion and accumulation of micellar cholesterol by Caco-2 cells: control orange juice (OJ), orange juice supplemented with either multivitamin/multimineral tablets (MVT), multivitamin/multimineral tablets containing phytosterols (MVT+P), and phytosterol powder (PP). These combinations were added to Ensure-based test meals and spiked with cholesterol of natural isotopic composition or 13C2-cholesterol to differentiate external from endogenous cholesterol. After simulated gastric/small intestinal digestion, micelle fractions were analyzed for cholesterol enzymatically (n = 6-20/product) and by high-performance liquid chromatography-tandem mass spectrometry (n = 12/product) and added to Caco-2 cells to determine the accumulation of 13C2-cholesterol (n = 10-24/product). As compared to OJ, PP and MVT+P significantly decreased cholesterol micellarization (determined enzymatically) by 70 +/- 39 (mean +/- SD) and 70 +/- 39%, respectively (P < 0.001, Bonferroni). The stable isotope experiments revealed that both PP and MVT+P reduced cholesterol micellarization [by 25 +/- 12 (P = 0.055) and 21 +/- 8% (P = 0.020), respectively, Fisher's protected LSD test] and Caco-2 cell accumulation (by 28 +/- 8 and 10 +/- 8%, respectively; P < 0.010, Bonferroni). OJ+P did not inhibit micellarization or accumulation of cholesterol by Caco-2 cells. This study shows that fat-free phytosterol-containing products can significantly inhibit cholesterol micellarization and Caco-2 cell bioaccessibility, albeit to different extents depending on individual formulations. This is most likely explained by inhibition of cholesterol micellarization.

Assessment of the Gould-Shih procedure for sample size re-estimation.

The power of a clinical trial is partly dependent upon its sample size. With continuous data, the sample size needed to attain a desired power is a function of the within-group standard deviation. An estimate of this standard deviation can be obtained during the trial itself based upon interim data; the estimate is then used to re-estimate the sample size. Gould and Shih proposed a method, based on the EM algorithm, which they claim produces a maximum likelihood estimate of the within-group standard deviation while preserving the blind, and that the estimate is quite satisfactory. However, others have claimed that the method can produce non-unique and/or severe underestimates of the true within-group standard deviation. Here the method is thoroughly examined to resolve the conflicting claims and, via simulation, to assess its validity and the properties of its estimates. The results show that the apparent non-uniqueness of the method's estimate is due to an apparently innocuous alteration that Gould and Shih made to the EM algorithm. When this alteration is removed, the method is valid in that it produces the maximum likelihood estimate of the within-group standard deviation (and also of the within-group means). However, the estimate is negatively biased and has a large standard deviation. The simulations show that with a standardized difference of 1 or less, which is typical in most clinical trials, the standard deviation from the combined samples ignoring the groups is a better estimator, despite its obvious positive bias.

Addition of ibuprofen to pseudoephedrine and chlorpheniramine in the treatment of seasonal allergic rhinitis.

BACKGROUND: Patients with seasonal allergic rhinitis experience many nasal and concomitant nonnasal symptoms. Many patients also experience headaches and facial pain, pressure, or discomfort. Standard over-the-counter therapy with antihistamines and nasal decongestants often does not completely relieve all symptoms associated with allergic rhinitis. OBJECTIVE: To establish the contribution of ibuprofen when used with pseudoephedrine and chlorpheniramine, a standard over-the-counter regimen, to relieve the symptoms of seasonal allergic rhinitis. METHODS: In this 7-day, multicenter, randomized, placebo-controlled, double-blind, double-dummy, parallel-group trial, qualified subjects were randomly assigned to 1 of 4 treatment groups that received combined ibuprofen/pseudoephedrine/chlorpheniramine (200/30/2 mg or 400/60/4 mg), combined pseudoephedrine/chlorpheniramine (30/2 mg), or placebo. Therapy began when the subject experienced a minimum of moderate allergy-associated pain, and it continued 3 times a day for 7 consecutive days. RESULTS: Mean pain intensity reduction in both ibuprofen/pseudoephedrine/chlorpheniramine treatment groups was 40% greater than in the placebo group and 33% greater than in the pseudoephedrine/chlorpheniramine treatment group (P < .001). Mean changes from baseline in total and nonpain symptom scores for both ibuprofen/pseudoephedrine/chlorpheniramine doses were significantly greater than for placebo (P < .001) and pseudoephedrine/chlorpheniramine (P < .001-.05) but were not different from each other. Ibuprofen enhanced the chlorpheniramine and pseudoephedrine effects, resulting in incremental 33% to 34% pain relief and 17% to 22% allergy symptom relief compared with pseudoephedrine/chlorpheniramine. CONCLUSIONS: In both doses of the triple combination, ibuprofen added to the effects of chlorpheniramine and pseudoephedrine, resulting in superior relief of pain and all nonpain allergy symptoms compared with pseudoephedrine/chlorpheniramine treatment. Furthermore, the superior efficacy of the lower dose of the triple combination allowed for a decrease in the incidence of adverse effects.