Effects of rapeseed and soybean oil dietary supplementation on bovine fat metabolism, fatty acid composition and cholesterol levels in milk.

The main goal of this experiment was to study the effect of milk fat depression, induced by supplementing diet with plant oils, on the bovine fat metabolism, with special interest in cholesterol levels. For this purpose 39 cows were divided in three groups and fed different rations: a control group (C) without any oil supplementation and two groups with soybean oil (SO) or rapeseed oil (RO) added to the partial mixed ration (PMR). A decrease in milk fat percentage was observed in both oil feedings with a higher decrease of -1·14 % with SO than RO with -0·98 % compared with the physiological (-0·15 %) decline in the C group. There was no significant change in protein and lactose yield. The daily milk cholesterol yield was lower in both oil rations than in control ration, while the blood cholesterol level showed an opposite variation. The milk fatty acid pattern showed a highly significant decrease of over 10 % in the amount of saturated fatty acids (SFA) in both oil feedings and a highly significant increase in mono (MUFA) and poly (PUFA) unsaturated fatty acids, conjugated linoleic acids (CLA) included. The results of this experiment suggest that the feeding of oil supplements has a high impact on milk fat composition and its significance for human health, by decreasing fats with a potentially negative effect (SFA and cholesterol) while simultaneously increasing others with positive (MUFA, PUFA, CLA).

Influence of the leptin G-2548A polymorphism on leptin levels and anthropometric measurements in healthy Spanish adolescents.

Polymorphisms in the leptin gene (LEP) have been associated with leptin levels and obesity in some studies in adults though this link has scarcely been investigated in children. In our study, we examined the relationship of the LEP G-2548A polymorphism with leptin levels, anthropometric variables and body composition in a population-based sample of pubescent children. Our study included 880 healthy schoolchildren (419 males and 461 females), 12-16 years of age. Plasma leptin levels were determined by ELISA. The LEP polymorphism was determined by allelic discrimination TaqMan assay. Male carriers of the AA genotype had significantly lower plasma leptin levels than GA (p < 0.008) and GG (p < 0.001) carriers and significantly lower mean hip circumference (HC) values than GG carriers (p = 0.04). In girls, leptin levels were also lower in A-allele carriers than in GG carriers, and BMI and HC were significantly lower in AA carriers as compared with GG carriers. In addition, the frequency of the A allele was significantly lower (chi(2): 4.58, p = 0.032) in the OW-obese than in the NW group. In conclusion, the LEP G-2548A polymorphism is associated with variations in leptin levels, BMI and HC in Spanish pubertal children, and evidence suggests a link between the G allele and presence of overweight in girls.

Rapid method for cholesterol analysis in bovine milk and options for applications.

The adaptation of a colorimetric technique for the analysis of cholesterol in raw milk is presented. Performance quality was satisfying (mean intra-assay coefficient of variation (CV) 4.8, inter-assay CV 9.1%, linearity between 0 and 7 mm, recovery of spiked cholesterol into raw milk 98.1 and 106.3%). However, the milk fat extraction must be carried out within the 48 hours following milk sampling. When performing sampling, the significant variation of milk cholesterol composition during the milking process has to be taken into account.

Cholesterol synthesis in the lactating cow: Induced expression of candidate genes.

Despite the extensive knowledge for other species, cholesterol metabolism in ruminants is nowadays still not clear. Huge differences in milk cholesterol concentration are observed between breeds, managing strategies, individuals and moment of the lactating cycle, but the genetic actors working in the process of cholesterol secretion into milk have not been identified. As ruminant diet contains no cholesterol, understanding the mechanisms and regulation of synthesis, transport and secretion into milk is crucial when trying to reduce the amount of this metabolite in dairy products. The present work aims to study the expression of candidate genes for these processes in the liver of Bos taurus during the lactating cycle. Liver biopsies were obtained from 16 adult brown Swiss cows at different time points (2 weeks pre-partum and 0, 2, 4 and 8 weeks post-partum). After RNA extraction and reverse transcription, gene expression of candidate genes was studied using quantitative RT-PCR. Key enzymes of the cholesterol synthesis (3-hydroxy-methyglutaryl-coenzyme-A (HMG-CoA) synthase, HMG-CoA reductase and farnesyldiphosphat-farnesyltransferase (FDFT)) and gene expression feed-back regulators involved in lipid metabolism (sterol regulatory element binding proteins (SREBP1and 2) SREBP-cleavage activating protein (Scap) were selected as candidate genes. HMG-CoA-reductase and FDFT showed a huge expression increase until week 2 post-partum (p<0.01), most probably in response to the new requirements in the mammary gland. As well, and as a possible explanation for such modifications, an increase in the expression of the regulators SREBP1 and Scap was observed (p<0.01 and p<0.05 respectively). Most important, the whole synthesis machinery showed a coordinated regulation, as highly significant positive correlations were found between the expression levels of the above mentioned enzymes (p<0.01). The increase of milk and blood cholesterol levels in B. taurus after parturition might be the result of a coordinated induction in the expression of key liver enzymes and their regulating factors.

Análisis de la actividad paraoxonasa (PON1) y de los polimorfismos PON1 192 y PON1 55 en la población prepuberal del Estudio Cuatro Provincias / Serum paraoxonase activity and PON1 192 and PON1 55 polymorphisms in prepuberal children. The Four Provinces S

Introducción. La paraoxonasa 1 (PON1) es una éster hidrolasa presente en las lipoproteínas de alta densidad (HDL), relacionada con la eliminación de componentes oxidados de las lipoproteínas de baja densidad (LDL) y por ello con el riesgo cardiovascular. Nuestro estudio analiza la actividad PON1 y los polimorfismos 192 y 55 del gen PON1 en los niños de edad prepuberal integrantes del Estudio Cuatro Provincias. Métodos. La población de estudio la constituyen 1.275 niños de 6 a 8 años. La actividad PON1 en suero se determinó mediante la hidrólisis de paraoxon. Los polimorfismos genéticos PON1 192Q/R y PON1 55M/L se analizaron mediante amplificación por reacción en cadena de la polimerasa (PCR) y posterior análisis de restricción. Resultados. En nuestra población la frecuencia de los alelos PON192R y PON55M es del 30 y el 38%, respectivamente, sin diferencias significativas entre provincias. La actividad PON1 es más elevada en Orense y más baja en Murcia, tanto en la población total como para cada uno de los genotipos. En la provincia de Orense se observaron correlaciones significativas entre la actividad PON1 y los valores plasmáticos de colesterol total (CT), colesterol unido a HDL (cHDL) y apolipoproteína AI (apo AI). El análisis de regresión muestra que el polimorfismo PON1 192Q/R es el principal determinante de la actividad PON1 en nuestra población. Conclusiones. La frecuencia de los polimorfismos PON192 y PON55 no difiere significativamente entre provincias. Sin embargo, a pesar de que el polimorfismo PON192 es el principal determinante de la actividad PON1, Orense presenta la actividad PON1 más alta y Murcia la más baja, lo que sugiere que ya a esta edad existen factores que regulan esa actividad dentro de cada genotipo (AU)

Background. Paraoxonase (PON1) is an ester hydrolase related to the elimination of oxidized compounds of low-density lipoprotein (LDL) particles and therefore to cardiovascular risk. The aim of the present study was to analyze the relationship between serum PON1 activity and PON1 192 and 55 polymorphisms in the prepuberal children included in the Four Provinces Study. Methods. The study population included 1,275 children aged 6 to 8 years old. Serum PON1 activity was measured by paraoxon hydrolysis. PON1 192Q/R and PON1 55M/L polymorphisms were analyzed by polymerase chain reaction and restriction analysis. Results. In the population as a whole, the prevalence of the less common PON192R allele was 30% and that of the PON55M allele was 38%, without significant differences in the frequencies between provinces. PON1 activity was highest in Orense and lowest in Murcia, both in the group as a whole and within each genotype. In Orense, significant correlations between PON1 activity and plasma total cholesterol, high-density lipoprotein cholesterol and apolipoprotein AI levels were found. Regression analysis showed that the PON1 192Q/R polymorphism is the main determinant of PON1 activity in our population. Conclusions. No significant differences between provinces in the frequencies of the PON192 and PON55 polymorphisms were found. However, although the PON192 polymorphism is the main determinant of PON1 activity, Orense showed the highest activity and Murcia the lowest for all the genotypes, suggesting that already at this age some factors are regulating PON1 activity for each genotype (AU)

Functional polymorphism in ABCA1 influences age of symptom onset in coronary artery disease patients.

ATP-binding-cassette-transporter-A1 (ABCA1) plays a pivotal role in intracellular cholesterol removal, exerting a protective effect against atherosclerosis. ABCA1 gene severe mutations underlie Tangier disease, a rare Mendelian disorder that can lead to premature coronary artery disease (CAD), with age of CAD onset being two decades earlier in mutant homozygotes and one decade earlier in heterozygotes than in mutation non-carriers. It is unknown whether common polymorphisms in ABCA1 could influence age of symptom onset of CAD in the general population. We examined common promoter and non-synonymous coding polymorphisms in relation to age of symptom onset in a group of CAD patients (n = 1164), and also carried out in vitro assays to test effects of the promoter variations on ABCA1 promoter transcriptional activity and effects of the coding variations on ABCA1 function in mediating cellular cholesterol efflux. Age of symptom onset was found to be associated with the promoter - 407G > C polymorphism, being 2.82 years higher in C allele homozygotes than in G allele homozygotes and intermediate in heterozygotes (61.54, 59.79 and 58.72 years, respectively; P = 0.002). In agreement, patients carrying ABCA1 haplotypes containing the -407C allele had higher age of symptom onset. Patients of the G/G or G/C genotype of the -407G > C polymorphism had significant coronary artery stenosis (>75%) at a younger age than those of the C/C genotype (P = 0.003). Reporter gene assays showed that ABCA1 haplotypes bearing the -407C allele had higher promoter activity than haplotypes with the -407G allele. Functional analyses of the coding polymorphisms showed an effect of the V825I substitution on ABCA1 function, with the 825I variant having higher activity in mediating cholesterol efflux than the wild-type (825V). A trend towards higher symptom onset age in 825I allele carriers was observed. The data indicate an influence of common ABCA1 functional polymorphisms on age of symptom onset in CAD patients.

The ABCA subfamily--gene and protein structures, functions and associated hereditary diseases.

To date, 12 members of the human ABCA subfamily are identified. They share a high degree of sequence conservation and have been mostly related with lipid trafficking in a wide range of body locations. Mutations in some of these genes have been described to cause severe hereditary diseases related with lipid transport, such as fatal surfactant deficiency or harlequin ichthyosis. In addition, most of them are hypothesized to participate in the subcellular sequestration of drugs, thereby being responsible for the resistance of several carcinoma cell lines against drug treatment. The objective of this review is to summarize the literature for this subfamily of ABC transporter proteins, excluding ABCA1 and ABCA4, which will be discussed in other chapters of this issue.

Metabolic adaptation in the crew of the Hesperides on their Antarctic journey.

AIMS: We studied the metabolic changes that took place in the crew of the Hesperides vessel in their 2001-2002 Antarctic journey, comparing two periods differing in diet and physical activity. METHODS AND RESULTS: Lipid profile, vitamin and hormone levels were analyzed in 17 subjects who completed the study in its two phases. In phase I the participants spent 47 days sailing with hard work and rough seas, and the diet was rich in fat and poor in fresh foods. In this phase, glucose decreased and HDL-cholesterol, apo-AI, and TSH increased. Plasma retinol and alpha-tocopherol levels remained stable, gamma-tocopherol, alpha-carotene and beta-carotene significantly decreased, and lycopene significantly increased. Phase II lasted 49 days including a 7-day long stop in port. This meant that a more varied diet was available and fresh foods were present in the hold. There was also less extreme physical activity. The metabolic pattern changed direction, glucose rose, HDL-cholesterol and apo-AI decreased and the levels of the vitamins that dropped in phase I started to increase. Lycopene significantly decreased. CONCLUSION: Contrary to popular beliefs about navigation at extreme latitudes, the metabolic changes described may be explained by the intense physical activity in a cold environment and a high-fat diet poor in fresh products.

Cholesterol and saturated fat intake determine the effect of polymorphisms at ABCG5/ABCG8 genes on lipid levels in children.

PURPOSE: Analysis of mutations in genes of the cholesterol metabolic pathway has not completely explained the interindividual variability of blood cholesterol concentrations attributed to gene-nutrient interactions. Thus, we analyzed polymorphisms in the ABCG5 and ABCG8 genes, involved in the regulation of intestinal cholesterol absorption, with special interest in a potential interaction with diet to determine lipid levels. METHODS: The polymorphisms ABCG5 C1950G (Gln604Glu) and ABCG8 C1895T (Ala640Val) were determined by polymerase chain reaction and restriction analysis in 1227 healthy school children, aged 6 to 8 years. RESULTS: No significant differences were found in blood lipid levels between subjects with different genotypes of the two analyzed polymorphisms. However, important differences appeared when separating subjects by their different lipid intake. The presence of the ABCG8 C1895T and ABCG5 C1950G polymorphisms was associated with different plasma total cholesterol, low-density lipoprotein cholesterol complex, and apolipoprotein B levels only in low-cholesterol consumers (significantly for the C1895T polymorphism), and among children within the lower tertile of saturated fat intake (significantly for the C1950G polymorphism). CONCLUSION: Polymorphisms at the half-transporter ABCG5 and ABCG8 genes affect blood cholesterol concentrations in prepubertal children by influencing dietary responsiveness. This highly significant gene-nutrient interaction could explain the great individual differences in the plasma lipid response to cholesterol and fat intake.

Dehydroepiandrosterone sulfate (DHEA-S) distribution in Spanish prepuberal children: relationship with fasting plasma insulin concentrations and insulin resistance.

BACKGROUND: The aim of this study was to analyze dehydroepiandrosterone sulfate (DHEA-S) levels in a population-based sample of Spanish prepuberal children and to investigate the relationship between DHEA-S and insulin. METHODS: 854 (440 boys and 414 girls) randomly selected prepuberal children were included in our study after a sampling. Children were 6 to 8 years old and were classified for the analysis in half-year intervals. DHEA-S and insulin levels were measured. RESULTS: DHEA-S levels increase significantly with age during prepuberty reaching the maximum level of DHEA-S for this period at 7.5 years old in girls and 8 years old in boys. Girls have significantly higher log DHEA-S levels than boys, except at the age of 8, where the levels are similar (median: 41.7 nmol/l girls and 41.1 nmol/l boys). DHEA-S correlates positively and significantly with weight, height, and BMI in all age intervals but the correlation between DHEA-S and insulin and HOMA is present only at the age of 6.5 in boys and 8 in girls. CONCLUSIONS: We report data about the distribution of DHEA-S in the Spanish prepuberal population. The maximum level of DHEA-S in this prepuberal period was reached before in girls than in boys, with girls having higher DHEA-S levels than boys until the end of this period. We found an important association between DHEA-S levels and weight, height and BMI but an inconsistent association of DHEA-S with insulin and HOMA.

epsilon3epsilon4 genotype as risk factor of myocardial infarction in middle-aged people in Spain.

Apolipoprotein E (apoE) plays an important role in lipid metabolism. Its epsilon4 allele has been consistently associated with lipoprotein disorders but its connection to myocardial infarction (MI) is controversial. Because epsilon4 frequency decreases with age we thought that the contradictory results in different studies could be due to the wide age range of the subjects included. To test our hypothesis, ApoE genotyping was performed in 474 MI cases and an analysis was performed by percentiles of age. The frequencies of epsilon3epsilon4 genotype and epsilon4 allele in the MI group as a whole (subjects aged 31 to 92) were not significantly different from those in our area general population. However, significant differences were observed when comparing by group of age. The frequencies decreased as age increased. The epsilon3epsilon4 and epsilon4 frequencies were significantly higher in MI subjects aged 31 to 56 than in subjects over 74. The epsilon3epsilon4 genotype prevalence in an age and sex matched control group of subjects aged 31 to 56 was significantly lower than in the 31-56 year-old MI group. In conclusion, our data shows different epsilon3epsilon4 and epsilon4 frequencies depending on the age range of the subjects with MI, being significantly higher in the middle-aged group. This finding may help explain the discrepancies between studies analyzing association between apoE genotype and MI, and emphasizes the idea of considering apoE genotype for prevention at early age.

Insulin and HOMA in Spanish prepubertal children: relationship with lipid profile.

OBJECTIVE: The effects of insulin or insulin resistance on the lipid profile seem to change with age. The aim of this study was to analyze insulin levels and an insulin resistance index and to investigate the relationship between these and the lipid profile in a population-based sample of Spanish prepubertal children. METHODS: 1048 (524 boys and 524 girls) randomly selected prepubertal children were studied. Children were 6 to 8 years old with a mean age of 6.7. Plasma lipid, FFA and insulin levels were measured. The homeostatic model assessment (HOMA) was calculated as an indicator of insulin resistance. RESULTS: When analyzing percentile values of insulin, HOMA and FFA by sex, we observed that girls had significantly higher insulin concentrations than boys (except at the 10th percentile) and significantly higher FFA (except at the 90th percentile) with no significant differences between sexes for HOMA. Multivariate regression analyses showed that insulin was positively associated with glucose, triglycerides and apoB in boys but not in girls, and negatively associated with FFA in both genders. CONCLUSIONS: We report here data about the distribution of insulin in the Spanish prepubertal population. The higher levels of insulin in prepubertal girls could indicate that girls start to be more insulin resistant than boys at this age, although other manifestations of insulin resistance are not yet detectable.

Obesity in Spanish schoolchildren: relationship with lipid profile and insulin resistance.

This article reports cross-sectional data from a total of 1048 children, 6 to 8 years of age, categorized by presence or absence of obesity, who participated in a voluntary survey of cardiovascular risk factors in Spain over the period of 1998 to 2000, to establish the relationship between obesity and its metabolic consequences at this age. The prevalence of obesity and overweight were 9.4% and 15.7%, respectively, in boys and 10.5% and 18.0%, respectively, in girls. We observed that, in both sexes, obese children had higher triglycerides and lower high-density lipoprotein-cholesterol levels than non-obese children. No differences were found in plasma glucose or low-density lipoprotein-cholesterol levels between normal and obese children. However, we observed that insulin levels and the homeostasis model assessment for insulin resistance were significantly (p<0.001) higher in obese children of both sexes but that free fatty acid levels were lower in obese children than in nonobese children, with a statistical significance in girls (0.72+/-0.30 vs. 0.61+/-0.16 mEq/liter). In summary, our survey found some metabolic consequences of obesity similar to those found in adults (elevated triglycerides, insulin, and the homeostasis model assessment for insulin resistance, and lower high-density lipoprotein-cholesterol). However, other features (glucose, total cholesterol, low-density lipoprotein-cholesterol, and free fatty acid levels) were found to behave differently, indicating that the association of obesity with risk factors seems to change as the children age and may depend on the chronology of sexual maturation.

Consistently high plasma high-density lipoprotein-cholesterol levels in children in Spain, a country with low cardiovascular mortality.

Coronary heart disease (CHD) mortality is relatively low in Spain compared with other developed countries and has remained low despite an apparent increase in mean plasma cholesterol concentration in adults over the last several years. It is accepted that pathologic processes related to arteriosclerosis development begin in childhood and seem to be related to the presence of cardiovascular risk factors at this age. High-density lipoprotein-cholesterol (HDL-C) levels in children have been inversely correlated with the incidence of coronary heart disease in the different countries studied. Childhood plasma lipoprotein profile might contribute to the low coronary heart disease mortality in Spain. Thus, we analyzed data on lipid levels over time in schoolchildren in Spain in the last decade. Plasma lipid levels were analyzed in prepuberal children (6 to 8 years) in 3 school-based surveys performed by our group in Madrid in 1987, 1993, and 1999. A significant increase in plasma total cholesterol (P < .05) and low-density lipoprotein-cholesterol (LDL-C) (P < .01) levels in prepuberal children was observed over the last decade. However, the mean concentration of plasma HDL-C remained stable and very high. These high levels of plasma HDL-C in Spanish school children may help to explain why the coronary heart disease mortality rate in Spain is low compared with that in other developed countries.

Effects of dehydroepiandrosterone-sulfate on the Apo E genotype influence on plasma lipid levels in prepubertal children.

Gender differences in the apolipoprotein (apo) E genotype effect on plasma lipid levels reported in adults have also been found in pre-pubertal children. In adults, the difference seems to be due to the influence of sexual hormones. The reason why this difference exits between pre-pubertal girls and boys, for whom those sexual hormones are not different, is unclear. However, there is an important difference in Dehydroepiandrosterone-sulfate (DHEA-S) levels between pre-pubertal boys and girls. To evaluate the influence of DHEA-S on apo E genetic determinants of plasma lipids levels in pre-pubertal children we measured plasma DHEA-S in 1045 healthy children (534 males and 511 females) 6 to 8 years old in which a different apoE influence on lipid levels had been reported between girls and boys. Our observations demonstrate that the extent of the lipid increasing or decreasing effects associated with each allele were modulated by DHEA-S. DHEA-S increases the hypolipemic effect of the epsilon2 allele and decreases the hyperlipemic effect of the epsilon4 allele. In conclusion, the interaction of apo E genotype and DHEA-S may represent a critical determinant of TC, LDL-C and apo B levels in children at the prepuberal age.