Serum carotenoid levels (SC) have been proposed as a measure of dietary exposure to fruits and vegetables (FV) in several large diet intervention trials. Yet p-carotene metabolism studies and intervention trials have repeatedly identified low responders (LR), subjects whose serum levels do not appreciably rise with p-carotene dosing. As part of a series of long-term controlled feeding studies which included 5-6 servings of fruits and vegetables per day, a Healthy People 2000 Objective, we were able to (1) assess the proportion of LR, (2) whether low-response was a stable attribute, (3) which carotenoids are sensitive to variability in response and (4) whether SC can serve as a marker of FV exposure in intervention trials and population studies.We fed 48 healthy, nonsmoking, premenopausal women with plasma cholesterol levels 250th percentile (Lipid Research Clinics Prevalence Study) as a reference population 5-6 servings of FV per day as part of cholesterol-lowering diets. The study design involved a 40% fat as energy (en%), polyunsaturated : saturated fatty acid ratio (P: S) of 0.5 diet for 1 month followed by 5 months of either a 20en% fat, P : S 2.0,20en% fat, P : S 0.5 or 30en% fat, P : S 1.0 diet. Each 6-month study was performed in a different year starting in January and ending in June or July. Energy levels were adjusted to maintain body weight throughout each study and diets were consumed in the metabolism laboratory or packed for take-out. Every effort was made to keep the carotenoid content of the diets constant. Although plasma cholesterol decreased by 8% for all diets SC were only marginally affected by the decrease. Furthermore the different diets had no effect on SC.
With computer generated holograms (CGH) the testing possibilities of interferometers for plane and spherical specimen is widened to the test of aspherical surfaces. The wave from a transmission flat or a transmission sphere is formed by the CGH to fit the surface of an asphere or a cylinder. The availability of suitable CGHs is often the limitation for the production of precision aspheres. JENOPTIK can provide a custom made CGH within a short time. We will show the design principles and the layout of the CGHs. The optical properties and the known limitations will be presented on the basis of measurements of aspherical surfaces.
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