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The aim of this study was to evaluate the extent of lipid peroxidation and the response of the enzymatic and non-enzymatic antioxidant defence system in erythrocytes from full-term and premature infants at birth, after 3 and after 72 h of life.Twenty infants were selected and divided in two groups according to their gestational age. Blood samples were taken at birth, at 3 and at 72 h of life, erythrocytes were isolated and the following parameters were measured: fatty-acid profile, coenzyme Q, alpha-tocopherol, hydroperoxides and the activity of the antioxidant enzymes catalase, superoxide dismutase (SOD) and cytosolic glutathione peroxidase (cGPx).For the three studied periods, several differences between full-term and premature infants were found. Premature children showed a higher concentration of hydroperoxides, a lower level of alpha-tocopherol and lower SOD and cGPx activity (except for cGPx at birth). Moreover, n-3 polyunsaturated fatty-acids percentages (essential for good neonatal development) were higher in full term children throughout all the study.Results suggest a strong imbalance between oxidants and antioxidants in premature infants during their first 72 h of life, a situation which could lead to several pathologies. Therefore, further research is needed, including possible nutritional intervention (with antioxidant therapy, supplementation of essential fatty acids and other dietary constituents) before and after birth.

Mongrel dogs were fed, from weaning to 6 months of age, on one of two 9% lipid diets that differed only in the type of fat content (sunflower oil or virgin olive oil) to study their effects on exocrine pancreatic secretion, in the basal period and in response to food. In addition, the results were compared with those obtained in a previous work performed by us on dogs adapted for 8 months to diets containing a higher (15%) amount of the same dietary fats to further evaluate the influence of the amount of dietary fat and the length of the adaptation period. The results from the present study show that both the volume and bicarbonate secreted in the absence of stimuli are unaffected by the quality of dietary fat. In contrast, in response to food, the pancreatic juice flow and the bicarbonate output were significantly higher in the group of animals given the sunflower oil diet. The differences seem to be related with the oleic acid content in the diets and the effectiveness of this fatty acid in triggering the release of inhibitory peptides such as pancreatic polypeptide and peptide YY. The comparison between the results from our present and previous studies supports the afore-mentioned hypothesis and confirms the existence of a clear influence of the amount and type of dietary fat, especially the oleic acid content, upon the pancreatic response to food, without ruling out a role for the duration of the adaptation period.

In this paper we study the effect of long-term adaptation (twelve months) of lipidic parameters of miniature swine to diets enriched in saturated (lard; L-group), monounsaturated (olive-oil; O-group) and polyunsaturated (sunflower and fish-oil; S- and F-groups respectively). The experimental group with the highest level of total cholesterol, free cholesterol and phospholipids was the S-group. This group had as well levels of HDL-C and LDL-C significantly higher when compared with the remaining groups. The L-group had the lowest value of HDL-C. In spite of that, the index of artherogenicity (HDL/LDL+VLDL) was significantly higher in the L-group, followed by the O-, F- and S-group respectively. On the other hand, after 12 months adaptation we observed that the fatty acid composition of serum lipids clearly reflects the quality of the dietary fats. The O-group had significantly higher serum oleic acid levels than all the other groups, and its content in saturated fatty acids was the lowest. The same happens with red blood cell (Rbcs) membranes fatty acids but the effect is less marked. Membranes of the L-group were found to have the highest saturation index (SI) in Rbcs membranes, while the F-group had the highest unsaturation index (UI), followed by the O-group. Taken together, our findings show that the diet enriched in olive oil produces a lipid pattern intermediate between that obtained with the fish-oil-diet and the sunflower-oil-diet but with the advantage of Rbcs membranes with a lower amount of PUFAS. As it is known, membranes with high percentages of PUFAS are more accessible for peroxidation, and the degree of peroxidation of lipids is directly related with changes in the membranes functionality.

In dogs, the effect of dietary fat on bile cholesterol saturation index and the evolution of molar percentages of biliary lipids have been studied in both fasting and postprandial periods after a long-term adaptation period to diets which only differ in their lipidic source (olive oil and sunflower oil).It has been observed that for similar bile cholesterol saturation indexes in both groups, dietary fat altered differently biliary lipid composition through a double mechanism which involved bile acids and phospholipids.Dietary fat is postulated to affect differently the lipidic composition of bile as well as the biliary tree motility both during interdigestive and postprandial periods.

In dogs with a direct pancreatic fistula, a duodenal cannula and a catheter in a saphenous vein, plasma secretin levels, changes in the flow, bicarbonate and chloride concentrations of the exocrine pancreatic secretion as well as in the pH of intraduodenal content have been studied 12 hours after the ingestion of a standard diet. Under these conditions the pancreatic secretion showed a biphasic response with a maximum flow and bicarbonate concentration during the 0-4 and 8-12 h postprandial periods. This coincided with a marked decrease of pH in the intraduodenal content, with values close to 4.5. On the other hand, during the first postprandial hour, plasma secretin values increased from basal ones (218.66 +/- 27 pg/ml) to 448.94 +/- 66 pg/ml, remaining elevated for four hours after the meal ingestion. However, no increase occurred between 8-12 h when intraduodenal pH reached values below 4.5. This study indicated that: 1) plasma secretin levels increased significantly (P less than 0.05) after the ingestion of a standard solid diet, and 2) determinants liberating secretin were not only the presence of a duodenal pH below 4.5, but probably the presence of some macronutrients from the meal.