Biomedical subjects
Publications and source records attributed to O Angulo.
We formulate schemes for the numerical solution of size-dependent population models. Such schemes discretize size by means of a natural grid, which introduces a discrete dynamics. The schemes are analysed and optimal rates of convergence are derived. Some numerical experiments are also reported to demonstrate the predicted accuracy of the schemes.
The purpose of the present study was to test the suitability of the solids of nejayote (a waste product from the tortilla industry) in diets for broilers. The nejayote was obtained from two different tortilla-making factories and the solids were obtained by centrifuge then dried in a hot-air drier. Diets were formulated to be isocaloric and isonitrogenous according to the NRC dietary requirements (1994). Nejayote solids were supplemented at 2, 4, and 6% of the diet. Results show that the content of protein and calcium in the dried solids of nejayote were 5 and 13%, respectively. The performance of broilers fed diets supplemented with dried nejayote did not differ from that of those fed the control diet. Therefore, it is concluded that nejayote solids are suitable for broiler feed and do not affect growth performance. Utilization of nejayote solids at higher levels is a possibility provided that no adverse effects on body weight, feed utilization, and feed:gain ratios are observed.
Research on dietary polyunsaturated fatty acids (PUFA), on the activity of 5'nucleotidase and adenylate cyclase are largely contradictory due, mostly, to the absence of adequate control group. In this study; four different diets have been evaluated on the 5'nucleotidase and adenylate cyclase activities in rat liver plasma membranes. Wistar rats were given a semisynthetic diet in which lipids were supplied by 5% of either peanut oil (n-3 PUFA deficient diet), cod liver oil (n-6 PUFA deficient diet) partially hydrogenated palm oil (total PUFA deficient diet) and a mixture of peanut and rapeseed oil (control group). Liver plasma membranes were separated by using a Percoll gradient in a Beckman JA 20 centrifuge. 5'nucleotidase and adenylate cyclase activities were measured in a liquid scintilation detector by following the degradation of 3HAMP (adenosine monophosphate) and production of 3HcAMP (cyclic adenosine monophosphate) respectively. Animals fed the total PUFA deficient diet exhibited significant lower body weight and lower liver weight than did the control group. Low cholesterol concentrations were observed in animals deficient either in n-3 or total PUFA in relation to the control group. All dietary deficiencies studies provoked reduced phospholipid levels. Phosphatidylcholine and phosphatidylethanolamine were not modified whatever the deficiency studied. Phospholipids fatty acid composition was significantly modified by the diets studied. The specific activity of 5'nucleotidase in hepatic plasma membrane was independent of dietary PUFA. The catalytic unit of adenylate cyclase complex in totally deficient animals was augmented. The unit of the enzyme stimulated by the guanydyl imidodiphosphate (GppNHp) in n-3 PUFA deficient animals was augmented and reduced in animals receiving the n-6 PUFA deficient diet. In conclusion, our results show that each dietary PUFA deficiency modifies differently the proportions of phospholipid classes and their fatty acid composition. The mechanisms responsible for these modification remain to be elucidated. However, the phospholipid fatty acid changes did not influence the 5'nucleotidase activity except in the case of extreme excess which concerns more toxicology than nutritional modifications. Finally, the catalytic unit (Forskoline + GDP beta s) of adenylate cyclase complex and the regulatory unit (GppNHp) may be sensitive to alterations in PUFA composition.
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We present an efficiency study for autonomous and non-autonomous non-linear size-structured population models. The study considers three numerical methods: a characteristics scheme, the Lax-Wendroff method and the box method, which are completely described in the paper. Five test problems are considered with diverse degree of complexity: non-trivial equilibrium, periodic solutions and diverse growth functions. The study of the efficiency takes into account the properties of the numerical schemes (such as the stability) and uses a multiple regression analysis to determine the constants of the leading terms of the corresponding global errors. We show how the tables of errors and cpu-times can be used to explain the meaning of the efficiency results. In addition, we present the convergence analysis of the box method.
OBJECTIVE: The effect of n-3 polyunsaturated fatty acids on the serum lipid profile in a Mexican population was evaluated. MATERIAL AND METHODS: Three g of salmon oil was the daily intake during four weeks. Total cholesterol, triglycerides, low density lipoproteins, high density lipoproteins and erythrocyte fatty acid composition were analyzed. RESULTS: The hypertriglyceridemic group showed a statistically significant (p < 0.05) reduction of triglycerides and significant (p < 0.01) elevation of high density lipoproteins. The hypercholesterolemic group reduced significantly the levels of cholesterol and triglycerides; high density lipoproteins were augmented by 11.6%. CONCLUSIONS: The hypolipidemic effect of n-3 polyunsaturated fatty acids was manifest in the Mexican volunteers under the conditions here evaluated.
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