Biomedical subjects

M J Mazier

Publications and source records attributed to M J Mazier.

4 recordsLinked to original sources

PubMed1999

Dietary fat saturation, but not the feeding state, modulates rates of cholesterol esterification in normolipidemic men.

To determine whether the rates of cholesterol esterification in normal individuals are affected by diets differing in fats, nine men were randomly assigned to three groups receiving a diet rich in monounsaturated (MONO), polyunsaturated (POLY), or saturated (SAT) fat for 2 weeks using a crossover design. Subjects drank a dose of deuterium oxide, and the fractional esterification rate (FER) was calculated during fed and unfed periods. Total esterified cholesterol was calculated as the product of the FER and pool size, the latter obtained from a decay curve following injection of [4-14C]-cholesterol. The POLY diet produced the lowest serum cholesterol concentration and the SAT diet the highest (P < .001). For cholesterol ester (CE) deuterium enrichment, an interaction was noted between diet and time (P < .01). The FER was greater (P < .003) in subjects fed the POLY diet versus either of the other diets, although the amount of esterified cholesterol produced, expressed as either milligrams per day (P < .103) or milligrams per kilogram of body weight per day (P < .100), did not differ among groups. No effect of the feeding state was found for either the FER (P < .187) or total esterified cholesterol expressed as milligrams per day (P < .146) or milligrams per kilogram of body weight per day (P < .128). The results suggest that the diet fat type, but not the feeding state, may be responsible for serum esterified cholesterol concentrations.

Adult↗

PubMed1997

Diet fat saturation and feeding state modulate rates of cholesterol synthesis in normolipidemic men.

To determine whether diets differing in fats affect cholesterol synthesis in normal individuals, nine men were randomly assigned to three groups that received three diets in a crossover design for 2 wk. Diets were either monounsaturated (MONO), polyunsaturated (POLY), or saturated (SAT). Subjects then drank a dose of deuterium oxide, and unesterified cholesterol fractional synthesis rates (FSR) were calculated during consecutive fed and unfed periods. Absolute synthesis was calculated as the product of FSR and pool size, the latter obtained from a decay curve following a [4-(14)C]cholesterol injection. Serum cholesterol concentrations varied with each diet consumed (P = 0.001); the SAT diet produced the highest and the POLY diet the lowest. Triglyceride concentrations were highest when subjects consumed the SAT diet and lowest with the POLY diet (P = 0.03); values obtained with the MONO diet did not differ significantly from those seen otherwise. HDL cholesterol concentrations were lowest when the SAT diet was consumed, highest when subjects were fed the MONO diet (P = 0.05), and midway but not significantly different with the POLY diet. Cholesterol FSR were greater when subjects consumed (P = 0.001) rather than not, and FSR during 12-h periods were greater (P = 0.045) when subjects ate the POLY diet rather than the SAT diet. Absolute synthesis was also greater (P = 0.04) when subjects were fed, but did not differ with fat type (P = 0.789). Results suggest that cholesterol synthesis is greater when men are fed than when they are not fed, and reduced synthesis is not responsible for the effect of different fats on cholesterol concentrations.

Adult↗

PubMed1994

Model-based compartmental analyses in nutrition research.

Kinetic tracer studies have been used extensively in understanding digestion, absorption, and whole-body metabolism of nutrients. Optimal interpretation of changes in tracer levels over time and movement across body pools often requires sophisticated data analysis. The use of model-based compartmental analysis (MCA) can yield more detailed quantitative and predictive information concerning system dynamics, compared with direct stochastic approaches. With MCA, tracer and tracee data from both experimental and literature values are fit to a model that best approximates the system on the basis of experimental data at hand. The number of compartments of the model is determined by the shape of the curve fit to the tracee and tracer data and by literature information. On this basis, MCA can yield information about compartment numbers and sizes, fractional and net turnover, as well as catabolic and synthetic rates. PC-based MCA programs are now available. Whereas earlier editions required use of a programming language, the most recent versions being developed are completely menu driven. Model-based compartmental analyses thus represent important biotechnological advances permitting maximal interpretation of kinetic data in nutrition research.

Animal Nutritional Physiological Phenomena↗

PubMed1991

Dietary fat quality and circulating cholesterol levels in humans: a review of actions and mechanisms.

Consumption of saturated fats contributes to elevated circulating cholesterol levels, whilst either polyunsaturated or monounsaturated fats are linked to depressed levels. Since elevated serum cholesterol is a risk factor for coronary heart disease, it is of interest to understand the factors responsible for the responses elicited by dietary fat quality. Changes in faecal sterol excretion, exogenous cholesterol absorption, lipoprotein composition, and lipoprotein catabolism can coincide with changes in fat intake but may not necessary cause them. Whether or not rates of whole-body cholesterol synthesis respond to dietary fat quality is not known. To date, animal studies suggest that shifts in LDL receptor-mediated cholesterol transport are to blame for responses of circulating cholesterol levels to dietary fat.

Cholesterol↗