Blood platelet function in healthy individuals of different ages. Effects of exercise and exercise conditioning.

The influence of age, physical conditioning and physical exercise on platelet function on human being is still controversial. The aim of our study were to evaluate the effect of physical exercise on platelet activation measured by beta-thromboglobulin (beta-TG) levels and the number of platelets in sedentary and athlete subjects of different ages, and also to investigate the response of these parameters during the period of recover immediately after a bicycle exercise test. Our results show differences in platelet count and beta-TG levels among the experimental groups studied, in basal conditions, in response to the exercise test and during postexercise period. These results seem to indicate that regardless age, regular physical exercise diminish age negative effects on platelet aggregation.

Lipid status in a population of Spanish schoolchildren.

We assessed lipid status in a population of 181 schoolchildren and adolescents divided into three age groups: 6-7 years (n = 60), 10-12 years (n = 61) and 13-15 years (n = 60). All subjects were from the Mediterranean coastal area of Vélez-Málaga in southern Spain. Nutrient intakes and biochemical parameters related with lipid status [total cholesterol (TC), HDL-chol, LDL-chol, VLDL-chol and triglycerides (TG)] were measured. Boys and girls aged 6-7 years had the same plasma concentrations of TC and TG; these concentrations were slightly higher than the mean values for age and sex found in earlier studies in Spanish populations. The high TC values were due mainly to increased concentrations of LDL-chol. This age group also had the largest percentage of members (26.6% boys, 36.6% girls) with plasma TC above 200 mg/dl. Of the groups aged 10-12 years, more girls than boys had abnormally high plasma cholesterol (16.1 vs 10%), HDL-chol (6.5 vs 0%) and TG concentrations (6.5 vs 0%). However, more adolescent boys than adolescent girls (aged 13-15 years) had abnormally low plasma concentrations of HDL-chol (10 vs 3.3%).

Long-term influence of dietary fat (sunflower oil, olive oil, lard and fish oil) in the serum fatty acid composition and in the different lipidic fractions, in miniature swine.

A total of 24 miniature swine (sus scrofa) was fed with four diets of 9% fat content, differing only in the quality of the fat source (sunflower oil, olive oil, lard fat and fish oil) for a 12 months period. After the experimental period, the influence of the dietary fat on the serum fatty acid composition, and the distribution of those fatty acids in the different serum lipidic fractions was studied. The olive oil group had the lowest SI value (total sum of saturated fatty acids) and the highest MUFA value (total sum of monounsaturated fatty acids) in serum. The sunflower group had higher proportions of n6 polyunsaturated fatty acids in serum, when compared with the remaining groups. The lard group and the fish oil group had both the highest values of SI and n3 polyunsaturated fatty acids. The results show that fatty acid composition in serum reflected, but not in all cases, the fatty acid composition of the diet. The highest correspondence was found with sunflower oil and olive oil diets. The existence of interactions between the different fatty acid series was evident, especially with the lard and the fish oil diets, as well as endogenous synthesis mechanisms. In lipidic fractions, higher correspondence with diet was found in EC fraction, but, as well as in serum, the existence of interactions between fatty acid series was evident, and especially activity and biosynthesis of desaturases may have been affected.

Influence of dietary fish on fatty acid composition of the erythrocyte membrane in coronary heart disease patients.

This study examines the effects of dietary fish oil on the fatty acid composition of the erythrocyte membrane in persons with coronary heart disease. Thirty men with myocardial infarction were studied during three consecutive periods, during which they consumed 1) their habitual diet, 2) a diet specially designed to prevent ischaemic cardiopathy, and 3) a diet rich in polyunsaturated fat, in which fish was substituted for meat. At the end of each diet, fatty acid concentrations in the erythrocyte membrane were measured, and a 48 h recall dietary questionnaire was used to determine the types of foods consumed. Despite the increase in the intake of (n-3) polyunsaturated fatty acids (PUFA), the fatty acid composition of the erythrocyte membrane failed to reflect the greater dietary supply of eicosapentaenoic acid, and showed increased concentrations of stearic (C16) and palmitic (C18) acid. The increase in dietary (n-3) polyunsaturated fatty acids markedly increased 22:4 (n-6), 22:5 (n-6), 22:5 (n-3) and 22:6 (n-3) fatty acids.

Long-term effects on lipid metabolism in miniature swine (Sus scrofa) of diets enriched in saturated, monounsaturated and polyunsaturated (N-6 and N-3) fatty acids.

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.

Influence of dietary supplementation with fish on plasma fatty acid composition in coronary heart disease patients.

The effects of dietary supplementation with fish on plasma fatty acid levels were studied in 20 coronary heart disease patients who had suffered acute myocardial infarction. The study was divided into three periods: hospital admission, after 8 weeks on a heart-healthy diet designed for patients with ischemic heart disease, and after 4 weeks on an n-3 fatty acid-supplemented diet in which red meat was replaced with lean and fatty fish. At the end of each period, the subjects responded to a 48-hour recall questionnaire, so that we could assess their compliance with the diet, and blood samples were collected for the determination of plasma fatty acids. Stearic fatty acid was significantly decreased after the fish diet. n-7 and n-9 fatty acids showed no significant changes throughout the study. At the end of the 4-week period when the fish diet was consumed, linoleic acid and its long-chain derivative docosapentaenoic acid (22:5 n-6) were significantly increased. The most notable changes in n-3 series fatty acids at the end of the third period were the significant decrease in linolenic acid and the significant increase in its long-chain derivatives eicosapentaenoic (20:5 n-3) and docosahexaneoic acid (22:6 n-3). These changes in plasma fatty acid levels may have beneficial effects on coronary heart disease.

Effects of adaptation to dietary fat on fatty acid composition of serum and serum lipids in miniature swine.

The influence of dietary fat on the serum fatty acid composition and distribution in different serum lipids was studied in 24 miniature swine (Sus scrofa) divided into 4 groups. Three groups were fed a low-fat chow with different kind of fats added (sunflower oil, olive oil and bovine lard) and the other group was fed a control diet with no fat added. The animals were fed the four diets for an experimental period of 12 weeks. Afterwards blood samples were taken to obtain serum, and the serum lipids were separated into the following fractions: phospholipids, triglycerides, and esterified cholesterol. The fatty acid composition of the serum and fractions was analyzed by gas chromatography. Under our experimental conditions, the fatty acid composition of the diets was reflected in serum, but not in all cases. In the triglyceride fraction the fatty acid composition was more evident. Our results show the interaction of the fatty acids in the different series and even within a single series, along with the endogenous synthesis processes.

Effects of adaptation to diets enriched with saturated, monounsaturated and polyunsaturated fats on lipid and serum fatty acid levels in miniature swine (Sus scrofa).

A total of 37 miniature swine (Sus scrofa) was fed with three diets of 9% fat content, differing only in the quality of the fat source (sunflower oil, olive oil and lard fat). Three groups of animals were fed for a 3 month period, and three other groups were fed for a 12 month period. After the two experimental periods, the influence of the diet on serum lipids and serum fatty acids was studied. In the short term, the serum cholesterol level was higher in the lard group, but with time, it undergoes a significant increase in the sunflower group, due to increases both in HDL-C and in LDL-C. In the olive oil group, LDL-C hardly varies with time, while HDL-C tends to decrease. In the lard group, LDL-C increases and HDL-C decreases. The atherogenic index is, in the long term, lower in the lard group and higher in the polyunsaturated fat group. The fatty acid composition of serum lipids in the long term shows a greater saturation index (SI) for the sunflower group and lard group, an increase in monounsaturated fatty acids in the olive oil group, and a higher percentage of linoleic acid in the sunflower group.

Peroxidative extent and coenzyme Q levels in the rat: influence of physical training and dietary fats.

Sport practice is widely recognized as capable of producing peroxidative damages, even of severe intensity. Dietary manipulations can also modify membrane susceptibility to peroxidation. In previous experiments we found that, while dietary virgin olive oil successfully protects mitochondrial and microsomal membranes from endogenous, xenobiotics-induced peroxidation, dietary polyunsaturated oils lead to increased peroxidative levels. In the latter conditions, cell machinery tries to counteract the structural and functional changes which have occurred, by modulating enzyme activities and concentrations, by increasing biosynthesis of coenzyme Q and by mobilizing cholesterol. In the present study we hypothesized that combining these two aspects could give useful information on the membrane response to peroxidation phenomena that daily occur throughout the lifespan. Rats fed different dietary oils as only fat source underwent a carefully designed training program and were killed at different times following acute or chronic exercise. Results show that peroxidation related to chronic training and to an acute bout of exercise sum up with peroxidative effects induced by dietary factors. The above mentioned phenomena occurred simultaneously with increased tissue levels of coenzyme Q, possibly triggered within a physiological reactive antioxidant strategy.

Iron status in a population of Spanish schoolchildren.

Iron status was assessed in a population of 196 schoolchildren and adolescents divided into three age groups: 6-7 years (n = 60), 10-12 years (n = 63) and 13-15 years (n = 73). All subjects were from the Vélez-Málaga area (province of Málaga) in southern Spain. Nutrient intakes and biochemical parameters related with iron status (number of red cells, hematocrit, hemoglobin, serum iron concentration, total iron-binding capacity and transferrin saturation) were measured. The results showed a lack of correlation between the nutrient intake and biochemical findings. Food intake calculations suggested that adolescent girls between 13 and 15 years of age were at greatest risk for iron deficiency (intakes covered only 71.6% and 84% of the iron and folic acid RDAs, respectively), followed by 10-12 year old girls and 6-7 year old boys. However, groups in which iron deficiency was most frequent according to the biochemical data were 6-7 year old boys (10%), followed by 13-15 year old adolescent boys (2.9%).

Role of vasoactive intestinal polypeptide (VIP), secretin and gastrin in the genesis of the late exocrine pancreatic hypersecretion, food intake dependent in conscious dogs.

Plasma levels of vasoactive intestinal polypeptide (VIP), secretin and gastrin were studied in four saphenous vein-catheterized dogs during the first 12 h after ingestion of a standard solid meal. Under these conditions we found significant postprandial increases in secretion only, which rose from a basal value of 219 +/- 27 pg/ml to 449 +/- 66 pg/ml 60 min postprandial (p < 0.001), and remained elevated until 4 h after food intake. However, no increase was seen from 8 to 12 h in any of the hormones studied, indicating that they are not directly involved in the enhancement of exocrine pancreatic secretion during this period.

Distal ileum resection totally suppresses the late pancreatic postprandial hypersecretion in conscious dogs.

Exocrine pancreatic secretion and serum levels of secretin, vasoactive intestinal peptide (VIP) and gastrin within postprandial 12 hours have been studied in dogs that have undergone a partial ileum resection (last 25 cm) 4 weeks before. In these conditions the following effects were observed: 1) the flow of pancreatic juice secreted after the food intake (1-4h period) was strictly similar to the flow described in intact dogs which did not suffer that surgical manipulation but it came back to its basal value more rapidly; 2) there were no effects regarding the postprandial hormonal pattern; 3) the late pancreatic hypersecretion period that is usually observed in intact dogs within the postprandial 8-12 h period, completely disappeared. These results allow to conclude that the mechanisms inducing the late hypersecretion process that usually takes place within the postprandial 8-12 h in dogs are generated in the distal ileum.

Effect of dietary fat composition on biliary cholesterol saturation index in dogs.

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.

Long-term effects of dietary monounsaturated and polyunsaturated fatty acids on plasma lipids in dogs.

To compare the effect of monounsaturated vs. polyunsaturated fatty acids on plasma lipids, three months old dogs were studied for a period of six months. The dogs were fed a basal diet supplemented with either 14% olive oil or sunflower oil. Blood samples were taken fortnightly during this period. We have found changes in the various unsaturated fatty acids in response to the diet. Oleic and 20:3 n-9 acids were higher in the olive oil group while linoleic acid was increased in the dogs fed the sunflower oil diet. Arachidonic acid and PUFA n-3 > 18C index were nearly similar with both diets. The cholesterol levels were similar to those found in adult humans and no significant differences were brought about diets at any time. Thus a diet rich in monounsaturated fatty acids is as efficient as a polyunsaturated rich in relation to total cholesterol levels but more beneficial because of the antiatherogenic effect of HDL-cholesterol which is increased with this type of dietary fat.

Adaptation of biliary response to dietary olive oil and sunflower-seed oil in dogs.

The effects of adaptation to dietary fat of different degrees of unsaturation (olive oil and sunflower oil) on bile secretion were studied in dogs at rest and after food intake. The animals were prepared with a bidirectional biliary cannula and a duodenal cannula to provide bile return. The two experimental groups were fed on diets containing 150 g fat/kg in the form of either olive oil (O) or sunflower-seed oil (S). The flow-rate under resting conditions and the patterns of response to food were similar in both experimental groups, although postprandial hypersection were significantly greater in volume and more prolonged in group O. No appreciable differences in concentration and output of biliary cholesterol or phospholipids were noted between the two groups. In contrast, the concentration and output of bile acids differed significantly both at rest and after food: concentration and output of bile acids were greater at rest in group S. However, after food intake, these responses were increased only in group O. The results suggest that the type of dietary fat affects biliary response to food, probably through differences in the contribution of the gall bladder in the two experimental groups.

Long-term effects of dietary monounsaturated and polyunsaturated fatty acids on the lipid composition of erythrocyte membranes in dogs.

1. Lipid analyses were conducted on erythrocyte membranes from dogs fed for 6 months with a normal defatted diet supplemented with either olive or sunflower oil. 2. Levels of palmitic, stearic and arachidonic acids were only slightly affected by dietary fat. 3. The unsaturated fatty acids of n-9 series were elevated in all the phospholipid fractions analysed for olive oil-fed dogs while the n-6 fatty acids, with the exception of arachidonic acid, were elevated in sunflower oil-fed dogs. 4. In the olive oil group the 20:5 (n-3) acid was higher than in the sunflower oil group. 5. The unsaturation index and the cholesterol/phospholipid ratio increased along the time course in the sunflower oil group. Both increases are complementary in order to maintain the constant fluidity of membranes.

Late postprandial pancreatic secretion periods in conscious dogs. Effect of vagotomy.

It is well established that, in the dog, the exocrine pancreatic secretion in response to food intake is a two-phased mechanism with a first phase during 0-4 h period and a second one during 8-12 h period. In the present study we have investigated the role played by the vagus nerve in the genesis of this late pancreatic hypersecretion (second phase) in dogs with truncal vagotomy and pyloroplasty. Truncal vagotomy totally suppressed the first phase of the pancreatic secretion; it did not abolish the second postprandial phase but it increased its latency by delay of 4 hours. In fact, during the 12-18 h period a pancreatic hypersecretory response was evidenced after vagotomy which appeared to be statistically significant as compared to basal values (P less than 0.001). Our results indicate that the vagus nerve does not play a role in the genesis of the late hypersecretory second phase.

Plasma lipid composition in an elderly population: correlation with dietary fat.

The effects of dietary fat on plasma lipid composition were studied in a population of 51 elderly subjects (19 men, 32 women) who lived in a retirement home in the province of Jaén (southern Spain). Dietary intake of fat was elevated (106 and 115 g/day in men and women respectively), and fatty acid intake consisted of 40% oleic acid, 17% linoleic acid and 0.7% linolenic acid. Cholesterol intake was 506 and 518 mg/day in men and women respectively, whereas the plasma level of cholesterol was approximately 250 mg/dl in both sexes. In men and women, HDL-cholesterol levels were 71.5 and 62.2 mg/dl, and LDL-cholesterol levels were 153.5 and 152.3 mg/dl. The most abundant circulating fatty acid was palmitic acid (25%) in both sexes, followed by oleic (23%) and linoleic acid (15-16%), whereas linolenic acid represented only 0.3% of the plasma fatty acids. To determine whether plasma levels of fatty acids served as reliable biological markers of dietary fatty acid intake, we compared the two sets of values, and found that higher intake was reflected in higher plasma levels, although a significant linear correlation (p < 0.05) was found only for linolenic acid.

Mitochondrial and microsomal cholesterol mobilization after oxidative stress induced by adriamycin in rats fed with dietary olive and corn oil.

The influence of three different dietary fats (8%) and of endogenous lipid peroxidation with regard to cholesterol concentrations in liver mitochondria and microsomes and in serum has been investigated in the rat. Although the different diet fat used did not produce any effect on serum cholesterol, it was possible to show that each experimental diet differently influenced the microsomal and mitochondrial levels of cholesterol. The highest mitochondrial and microsomal cholesterol content was found in case of diet supplemented with virgin olive oil and the lowest with rectified olive oil. An endogenous oxidative stress induced by adriamycin was able to produce a clear decrease in microsomal and mitochondrial cholesterol level and a sharp increase in serum concentration in all three groups. However, dietary fats and adriamycin had no effect on the microsomal and mitochondrial membrane viscosity as detected by fluorescence polarization. These results are consistent with the hypothesis that mitochondrial and microsomal cholesterol can exchange with exogenous pools when phospholipid peroxidation occurs.