Food groups, diet quality and colorectal cancer risk in the Basque Country

BACKGROUND

The results obtained to date concerning food groups, diet quality and colorectal cancer (CRC) risk vary according to criteria used and the study populations.

AIM

To study the relationships between food groups, diet quality and CRC risk, in an adult population of the Basque Country (North of Spain).

METHODS

This observational study included 308 patients diagnosed with CRC and 308 age- and sex-matched subjects as controls. During recruitment, dietary, anthropometric, lifestyle, socioeconomic, demographic and health status information was collected. Adherence to the dietary recommendations was evaluated utilizing the Healthy Eating Index for the Spanish Diet and the MedDietScore. Conditional logistic regressions were used to evaluate the associations of food group intakes, diet quality scores, categorized in tertiles, with CRC risk.

RESULTS

The adjusted models for potential confounding factors showed a direct association between milk and dairy products consumption, in particular high-fat cheeses [odds ratio (OR) third tertile vs first tertile = 1.87, 95% confidence intervals (CI): 1.11-3.16], and CRC risk. While the consumption of fiber-containing foods, especially whole grains (OR third tertile vs first tertile = 0.62, 95%CI: 0.39-0.98), and fatty fish (OR third tertile vs first tertile = 0.53, 95%CI: 0.27-0.99) was associated with a lower risk for CRC. Moreover, higher MD adherence was associated with a reduced CRC risk in adjusted models (OR third tertile vs first tertile = 0.40, 95%CI: 0.20-0.80).

CONCLUSION

Direct associations were found for high-fat cheese, whereas an inverse relation was reported for fiber-containing foods and fatty fish, as well as adherence to a Mediterranean dietary pattern.

Fermented dairy products, diet quality, and cardio-metabolic profile of a Mediterranean cohort at high cardiovascular risk

BACKGROUND AND AIMS

Fermented dairy products have been associated with a better diet quality and cardio-metabolic profile. However, in Mediterranean populations, these associations have not been well characterized. The aim of this study was to assess the diet quality and the associations between the consumption of total fermented dairy products and their subtypes and the prevalence of Metabolic Syndrome (MetS) components in a Mediterranean population at high cardiovascular risk.

METHODS AND RESULTS

Baseline cross-sectional analyses were conducted on 6,572 men and women (mean age: 65 years) with overweight or obesity and MetS recruited into the PREDIMED-Plus cohort. A 143-item Food Frequency Questionnaire (FFQ) was used, and anthropometrical, biochemical, and blood pressure measurements were recorded. Multivariate-adjusted Cox regressions were fitted to analyze the association between quartiles of consumption of fermented dairy products and their subtypes and MetS components to estimate the relative risk (RR) and 95% confidence intervals (95% CIs). Participants who were high consumers of fermented dairy products reported a higher consumption of fruit, vegetables, fish, nuts, and whole bread and a lower consumption of white bread, alcohol, and cookies. Participants in the higher quartile showed a lower prevalence of the low HDL-cholesterol component of the MetS (RR=0.88; 95% CI: 0.78-0.98) than those in the lowest quartile of cheese consumption. Cheese consumption was inversely associated with the prevalence of hypertriglyceridemia. Total fermented dairy products, yogurt, and its types were not associated with any of the MetS components.

CONCLUSIONS

Compared to nonconsumers, participants consuming fermented dairy products reported a better diet quality and, particularly, cheese consumers presented a lower prevalence of hypertriglyceridemia and low HDL-cholesterol plasma levels, which are MetS components.

Dietary fat modulation of hepatic lipase variant -514 C/T for lipids: a crossover randomized dietary intervention trial in Caribbean Hispanics

The hepatic lipase (LIPC) locus is a well-established determinant of high-density lipoprotein cholesterol (HDL-C) concentrations, an association that is modified by dietary fat in observational studies. Dietary interventions are lacking. We investigated dietary modulation of LIPC rs1800588 (-514 C/T) for lipids and glucose using a randomized crossover design comparing a high-fat Western diet and a low-fat traditional Hispanic diet in individuals of Caribbean Hispanic descent (n = 42, 4 wk/phase). No significant gene-diet interactions were observed for HDL-C. However, differences in dietary response according to LIPC genotype were observed. In major allele carriers (CC/CT), HDL-C (mmol/l) was higher following the Western diet compared with the Hispanic diet: phase 1 (Western: 1.3 ± 0.03; Hispanic: 1.1 ± 0.04; P = 0.0004); phase 2 (Western: 1.4 ± 0.03; Hispanic: 1.2 ± 0.03; P = 0.0003). In contrast, HDL-C in TT individuals did not differ by diet. Only major allele carriers benefited from the higher-fat diet for HDL-C. Secondarily, we explored dietary fat quality and rs1800588 for HDL-C and triglycerides (TG) in a Boston Puerto Rican Health Study (BPRHS) subset matched for diabetes and obesity status (subset n = 384). In the BPRHS, saturated fat was unfavorably associated with HDL-C and TG in rs1800588 TT carriers. LIPC rs1800588 appears to modify plasma lipids in the context of dietary fat. This new evidence of genetic modulation of dietary responses may inform optimal and personalized dietary fat advice and reinforces the importance of studying genetic markers in diet and cardiometabolic health.

Lipoprotein lipase variants interact with polyunsaturated fatty acids for obesity traits in women: replication in two populations

BACKGROUND AND AIMS

Lipoprotein lipase (LPL) is a candidate gene for obesity based on its role in triglyceride hydrolysis and the partitioning of fatty acids towards storage or oxidation. Whether dietary fatty acids modify LPL associated obesity risk is unknown.

METHODS AND RESULTS

We examined five single nucleotide polymorphisms (SNPs) (rs320, rs2083637, rs17411031, rs13702, rs2197089) for potential interaction with dietary fatty acids for obesity traits in 1171 participants (333 men and 838 women, aged 45-75 y) of the Boston Puerto Rican Health Study (BPRHS). In women, SNP rs320 interacted with dietary polyunsaturated fatty acids (PUFA) for body mass index (BMI) (P = 0.002) and waist circumference (WC) (P = 0.001) respectively. Higher intake of PUFA was associated with lower BMI and WC in homozygotes of the major allele (TT) (P = 0.01 and 0.005) but not in minor allele carriers (TG and GG). These interactions were replicated in an independent population, African American women of the Atherosclerosis Risk in Communities (ARIC) study (n = 1334).

CONCLUSION

Dietary PUFA modulated the association of LPL rs320 with obesity traits in two independent populations. These interactions may be relevant to the dietary management of obesity, particularly in women.

Toward a chronobiological characterization of obesity and metabolic syndrome in clinical practice

BACKGROUND & AIMS

To test several circadian rhythm variables in a female population to identify the best tool to assess chronodisruption in obesity and metabolic syndrome (MetS) to define a score to be used for chronodisruption characterization in clinical practice.

METHODS

Anthropometric measurements and markers of circadian rhythms, such as sleep and feeding diary, Horne-Ostberg questionnaire, melatonin and cortisol measurements, and wrist temperature measurements, were determined. MetS variables were also analyzed. Study was conducted in 70 women. Data were subjected to factor analysis. Receiver operating characteristic curves were used as predictors of chronodisruption risk, and a score was calculated to classify the subjects of risk.

RESULTS

Factor analysis showed that the first-factor grouped variables were related to the skin temperature measurement. Second factor consisted of variables related to salivary cortisol levels and obesity-related measurements. Third factor included variables related to sleep-wake cycle. Fourth factor referred to peripheral temperature variables and included the classification of subjects according to the Horne-Ostberg questionnaire. To obtain a final punctuation we performed the weighted mean of the first four factors. The final range was from 27 to 57, mean value of 42. Punctuation was defined as the "chronodisruption score." Women displaying higher chronodisruption scores had higher MetS risk.

CONCLUSION

The study demonstrates that wrist temperature recordings, together with two questions of sleep onset and offset, and one morning salivary cortisol determination could be enough to characterize the chronobiology of obesity and MetS, a new chronodisruption score was developed.

Can genotype be used to tailor treatment of obesity? State of the art and guidelines for future studies and applications

Current treatments for losing weight based mainly on diet and exercise are, in general, unsuccessful. So, as an alternative to the general strategy of one-size-fits-all, a more individualized approach is proposed through the so-called Personalised Medicine in which genotype data are used to personalize treatment and to optimize the results. This paper examines the current situation of the evidence on the influence of the genotype in modulating the association between diet or exercise on obesity and weight-related measures. Most of these studies are observational studies, as there are far fewer experimental ones assessing short-term weight-loss or its long-term maintenance. Many more studies are therefore required for that purpose. Having reviewed the results of the studies undertaken to date, we can say that huge progress has been made in identifying polymorphisms in genes related with obesity and that there is a great consistency of the influence of the FTO gene on the same, while for other variants, there is less consistency. Moreover, the results on gene-diet and gene-physical activity interactions in determining obesity phenotypes are very heterogeneous, so an important recommendation is to standardize the methodology for undertaking these studies. Furthermore, an important lack of replication has been observed suggesting undetected higher-level interactions and/or experimental caveats. Therefore, the current evidence level of applying genotype data to obesity treatment is at its early stages. Nevertheless, future prospects are encouraging and to make this come true, several guidelines are proposed for carrying out new studies on applications in clinical practice.

Perilipin polymorphism interacts with saturated fat and carbohydrates to modulate insulin resistance

BACKGROUND AND AIMS

Macronutrient intakes and genetic variants have been shown to interact to alter insulin resistance, but replications of gene-nutrient interactions across independent populations are rare, despite their critical importance in establishing credibility. We aimed to investigate a previously demonstrated saturated fat and carbohydrate interaction for insulin resistance for perilipin (PLIN1), a regulator of adipocyte metabolism.

METHODS AND RESULTS

We investigated the previously shown interaction for PLIN1 11482G > A (rs894160) on insulin resistance in US men (n = 462) and women (n = 508) (mean ± SD, 49 ± 16 years). In multivariable linear regression models, we found an interaction (P < 0.05) between the ratio of saturated fat to carbohydrate intake as a continuous variable and PLIN1 11482G > A for HOMA-IR (homeostasis model assessment of insulin resistance) in women. For carriers of the minor allele but not for non-carriers, as the ratio of saturated fat to carbohydrate intake increased, predicted HOMA-IR increased (P = 0.002). By dichotomizing the ratio of saturated fat to carbohydrate intake into high and low, we found significant interaction terms for insulin and HOMA-IR (P < 0.05). When the ratio of saturated fat to carbohydrate was high, insulin and HOMA-IR were higher in minor allele carriers (P = 0.004 and P = 0.003, respectively), but did not differ when the ratio was low. Similar patterns or trends were observed when saturated fat and carbohydrate were dichotomized into high and low as individual macronutrients.

CONCLUSIONS

Replication of the previously reported interaction between macronutrient intakes and PLIN1 genotype for insulin resistance reinforces the potential usefulness of applying genotype information in the dietary management of insulin resistance.

SIRT1 and CLOCK 3111T> C combined genotype is associated with evening preference and weight loss resistance in a behavioral therapy treatment for obesity

BACKGROUND

A new negative feedback loop has been proposed, which suggests connections between the circadian clock and SIRTUIN1 (SIRT1)-dependent functions associated with cell survival, development and metabolism.

OBJECTIVE

To develop a SIRT1 and circadian locomotor output cycles kaput (CLOCK) combined genotype and to assess its associations with the chronotype of subjects and their potential resistance to weight loss in a behavioral treatment for obesity based on a Mediterranean diet.

DESIGN

Overweight /obese subjects (n=1465), aged 20-65 years, who attended outpatient obesity clinics, were genotyped for SIRT1 (rs1467568) and CLOCK (3111T>C, rs1801260). Anthropometric, biochemical and dietary-intake variables were analyzed. Effectiveness of the program and weight loss progression during 30 weeks of treatment was assessed.

RESULTS

We found highly consistent associations between the morning/evening questionnaires across the different genotype categories. Subjects carrying minor alleles at SIRT1 and CLOCK loci (R group) displayed a higher resistance to weight loss and a lower weekly weight loss rate as compared with homozygotes for both major alleles (P group). Significant differences were found across genotypes in weight loss progression during the 30 weeks of treatment (P=0.039). Dietary habits indicated that R carriers had a lower intake of total carbohydrates and monounsaturated fats, and a higher intake of saturated fats than those carrying the intermediate (M) and the P genotype (P=0.02). Plasma ghrelin concentrations were also significantly higher in subjects carrying the R genotype.

CONCLUSION

Variants of both SIRT1 and CLOCK have an additive effect on resistance to weight loss that could be related to the chronotype of the subject, higher plasma levels of ghrelin and less adherence to Mediterranean diet patterns.

Sexual dimorphism in clock genes expression in human adipose tissue

BACKGROUND

This study was carried out to investigate whether sex-related differences exist in the adipocyte expression of clock genes from subcutaneous abdominal and visceral fat depots in severely obese patients.

METHODS

We investigated 16 morbidly obese patients, eight men and eight women (mean age 45 ± 20 years; mean BMI 46 ± 6 kg/m(2)), undergoing laparoscopic gastric bypass surgery. Biopsies were taken as paired samples [subcutaneous and visceral adipose tissue (AT)] at the beginning of the surgical process at 11:00 h in the morning. Metabolic syndrome features such as waist circumference, plasma glucose, triglycerides, total cholesterol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were also studied. The expression of clock genes (PER2, BMAL1, and CRY1) was measured by quantitative real-time PCR, Western blot, and immunohistochemical analysis.

RESULTS

Gene expression was significantly higher in women than in men for the three genes studied in both ATs (P < 0.05). In visceral fat, these differences were more marked. (P < 0.001). Western blot analysis partially confirmed these results since statistical differences were observed for PER2 in both ATs and for CRY1 in subcutaneous adipose tissue. There were no differences in BMAL1 protein expression. Interestingly, clock gene expression level was correlated with LDL-C and HDL-C (P < 0.05). Moreover, we found significant associations with body fat mass in women and with age in men.

CONCLUSIONS

Clock genes expression is sex dependent in human adipose tissue from morbidly obese subjects and correlates to a decreased in metabolic syndrome-related traits. These preliminary results make necessary to go deep into the knowledge of the molecular basis of the sexual dimorphism in chronobiology.

Differences in daily rhythms of wrist temperature between obese and normal-weight women: associations with metabolic syndrome features

The circadian rhythm of core body temperature is associated with widespread physiological effects. However, studies with other more practical temperature measures, such as wrist (WT) and proximal temperatures, are still scarce. The aim of this study was to investigate whether obesity is associated with differences in mean WT values or in its daily rhythmicity patterns. Daily patterns of cortisol, melatonin, and different metabolic syndrome (MetS) features were also analyzed in an attempt to clarify the potential association between chronodisruption and MetS. The study was conducted on 20 normal-weight women (age: 38 ± 11 yrs and BMI: 22 ± 2.6 kg/m(2)) and 50 obese women (age: 42 ± 10 yrs and BMI: 33.5 ± 3.2 kg/m(2)) (mean ± SEM). Skin temperature was measured over a 3-day period every 10 min with the "Thermochron iButton." Rhythmic parameters were obtained using an integrated package for time-series analysis, "Circadianware." Obese women displayed significantly lower mean WT (34.1°C ± 0.3°C) with a more flattened 24-h pattern, a lower-quality rhythm, and a higher intraday variability (IV). Particularly interesting were the marked differences between obese and normal-weight women in the secondary WT peak in the postprandial period (second-harmonic power [P2]), considered as a marker of chronodisruption and of metabolic alterations. WT rhythmicity characteristics were related to MetS features, obesity-related proteins, and circadian markers, such as melatonin. In summary, obese women displayed a lower-quality WT daily rhythm with a more flattened pattern (particularly in the postprandial period) and increased IV, which suggests a greater fragmentation of the rest/activity rhythm compared to normal-weight women. These 24-h changes were associated with higher MetS risk.

ADAM17_i33708A>G polymorphism interacts with dietary n-6 polyunsaturated fatty acids to modulate obesity risk in the Genetics of Lipid Lowering Drugs and Diet Network study

BACKGROUND AND AIMS

The disintegrin and metalloproteinase ADAM17, also known as tumor necrosis factor alpha converting enzyme, is expressed in adipocytes. Importantly, elevated levels of ADAM17 expression have been linked to obesity and insulin resistance. Therefore, the aim of this study was to evaluate the association of six ADAM17 single nucleotide polymorphisms (SNPs) (m1254A>G, i14121C>A, i33708A>G, i48827A>C, i53440C>T, and i62781G>T) with insulin-resistance phenotypes and obesity risk, and their potential interactions with dietary polyunsaturated fatty acids (PUFA).

METHODS AND RESULTS

ADAM17 SNPs were genotyped in 936 subjects (448 men/488 women) who participated in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study. Anthropometrical and biochemical measurements were determined by standard procedures. PUFA intake was estimated using a validated questionnaire. G allele carriers at the ADAM17_m1254A>G polymorphism exhibited significantly higher risk of obesity (P=0.003), were shorter (P=0.017), had higher insulin (P=0.016), and lower HDL-C concentrations (P=0.027) than AA subjects. For the ADAM17_i33708A>G SNP, homozygotes for the A allele displayed higher risk of obesity (P=0.001), were heavier (P=0.011), had higher BMI (P=0.005), and higher waist measurements (P=0.023) than GG subjects. A significant gene-diet interaction was found (P=0.030), in which the deleterious association of the i33708A allele with obesity was observed in subjects with low intakes from (n-6) PUFA (P<0.001), whereas no differences in obesity risk were seen among subjects with high (n-6) PUFA intake (P>0.5)

CONCLUSION

These findings support that ADAM17 (m1254A>G and i33708A>G) SNPs may contribute to obesity risk. For the ADAM17_i33708A>G SNP, this risk may be further modulated by (n-6) PUFA intake.

The chronobiology, etiology and pathophysiology of obesity

The effect of CD on human health is an emerging issue. Many records link CD with diseases such as cancer, cardiovascular, cognitive impairment and obesity, all of them conducive to premature aging. The amount of sleep has declined by 1.5 h over the past century, accompanied by an important increase in obesity. Shift work, sleep deprivation and exposure to bright light at night increase the prevalence of adiposity. Animal models have shown that mice with Clock gene disruption are prone to developing obesity and MetS. This review summarizes the latest developments with regard to chronobiology and obesity, considering (1) how molecular clocks coordinate metabolism and the specific role of the adipocyte; (2) CD and its causes and pathological consequences; (3) the epidemiological evidence of obesity as a chronobiological illness; and (4) theories of circadian disruption and obesity. Energy intake and expenditure, relevance of sleep, fat intake from a circadian perspective and psychological and genetic aspects of obesity are examined. Finally, ideas about the use of chronobiology in the treatment of obesity are discussed. Such knowledge has the potential to become a valuable tool in the understanding of the relationship between the chronobiology, etiology and pathophysiology of obesity.

Olive oil and health: summary of the II international conference on olive oil and health consensus report, Jaén and Córdoba (Spain) 2008

Olive oil (OO) is the most representative food of the traditional Mediterranean Diet (MedDiet). Increasing evidence suggests that monounsaturated fatty acids (MUFA) as a nutrient, OO as a food, and the MedDiet as a food pattern are associated with a decreased risk of cardiovascular disease, obesity, metabolic syndrome, type 2 diabetes and hypertension. A MedDiet rich in OO and OO per se has been shown to improve cardiovascular risk factors, such as lipid profiles, blood pressure, postprandial hyperlipidemia, endothelial dysfunction, oxidative stress, and antithrombotic profiles. Some of these beneficial effects can be attributed to the OO minor components. Therefore, the definition of the MedDiet should include OO. Phenolic compounds in OO have shown antioxidant and anti-inflammatory properties, prevent lipoperoxidation, induce favorable changes of lipid profile, improve endothelial function, and disclose antithrombotic properties. Observational studies from Mediterranean cohorts have suggested that dietary MUFA may be protective against age-related cognitive decline and Alzheimer's disease. Recent studies consistently support the concept that the OO-rich MedDiet is compatible with healthier aging and increased longevity. In countries where the population adheres to the MedDiet, such as Spain, Greece and Italy, and OO is the principal source of fat, rates of cancer incidence are lower than in northern European countries. Experimental and human cellular studies have provided new evidence on the potential protective effect of OO on cancer. Furthermore, results of case-control and cohort studies suggest that MUFA intake including OO is associated with a reduction in cancer risk (mainly breast, colorectal and prostate cancers).

Circadian expression of adiponectin and its receptors in human adipose tissue

Adiponectin is one of the most clinically relevant cytokines associated with obesity. However, circadian rhythmicity of adiponectin in human adipose tissue (AT) has not been analyzed. To assess whether the mRNA levels of adiponectin and its receptors (ADIPOR1 and ADIPOR2) might show daily circadian rhythms in visceral and sc fat explants obtained from morbid obese women, visceral and sc abdominal AT biopsies (n = 6) were obtained from morbidly obese women (body mass index >or=40 kg/m(2)). Anthropometric variables were measured and fasting plasma glucose, lipid, and lipoprotein concentrations were analyzed. To investigate rhythmic expression pattern, AT explants were cultured during 24 h, and gene expression was analyzed at the following times: 0800, 1400, 2000, and 0200 h, using quantitative real-time PCR. All genes investigated showed a circadian rhythmicity and oscillated accurately and independently of the suprachiasmatic nucleus in both AT explants (P < 0.05). Adiponectin gene expression fluctuated in the same phase as its receptors. Correlation analyses between the genetic circadian oscillation and components of the metabolic syndrome revealed that adiposity and abdominal obesity correlated with a decrease in adiponectin and adiponectin receptors ADIPOR1 and ADIPOR2 amplitude (P < 0.05). Visceral fat showed a trend toward a phase delay and dampening of the mRNA amplitude of adiponectin as compared with sc fat. The mRNA expression of adiponectin and its receptors showed 24-h rhythmicity in human AT from morbidly obese patients.

The -675 4G/5G polymorphism at the Plasminogen Activator Inhibitor 1 (PAI-1) gene modulates plasma Plasminogen Activator Inhibitor 1 concentrations in response to dietary fat consumption

The objective of the study was to determine whether Plasminogen Activator Inhibitor Type 1 (PAI-1) -675 4G/5G polymorphism is associated with the response of functional plasma PAI-1 concentrations to changes in the amount and quality of dietary fat in healthy subjects. PAI-1 is the major inhibitor of fibrinolysis, and a lower level of fibrinolytic activity could be implicated in an increased risk of IHD. Fifty-nine healthy Spanish volunteers (ten 4G/4G homozygotes, twenty-eight heterozygotes 4G/5G and twenty-one 5G/5G homozygotes) consumed three diets for periods of 4 weeks each: a SFA-rich diet (38 % fat, 20 % SFA), followed by a carbohydrate-rich diet (30 % fat, 55 % carbohydrate) and a MUFA-rich diet (38 % fat, 22 % MUFA) according to a randomized crossover design. At the end of each dietary period plasma lipid and functional plasma PAI-1 concentrations were determined. Subjects carrying the 4G allele (4G/4G and 4G/5G) showed a significant decrease in PAI-1 concentrations after the MUFA diet, compared with the SFA-rich and carbohydrate-rich diets (genotype x diet interaction: P = 0.028). 5G/5G homozygotes had the lowest plasma PAI-1 concentrations compared with 4G/4G and 4G/5G subjects (genotype: P = 0.002), without any changes as a result of the amount and the quality of the dietary fat. In summary, no differences in plasma PAI-1 concentration response were found after changes in dietary fat intake in 5G/5G homozygotes, although these subjects displayed the lowest concentrations of PAI-1. On the other hand, carriers of the 4G allele are more likely to hyper-respond to the presence of MUFA in the diet because of a greater decrease in PAI-1 concentrations.

Frequencies of apolipoprotein A4 gene polymorphisms and association with serum lipid concentrations in two healthy Spanish populations

Apolipoprotein A4 (apoA4) plays a role in intestinal lipid absorption. Several experimental interventions have shown that common variations at residues 347 (Thr --> Ser) and 360 (Gln --> His) on apoA4 are associated with differences in plasma lipid response to dietary fat; however, association studies between these variants and plasma lipid concentrations in populations reveal mixed results. We examined the effects of these polymorphisms in 758 randomly selected subjects (mean age 36.7+/-9.5 years) from 2 Spanish regions differing in latitude and fat intake: Aragón and Comunidad Valenciana. Subjects were matched one to one by sex and age. Frequencies for the less common alleles were similar in both regions: 0.096 (95% CI: 0.111-0.081) for codon 360 and 0.196 (95% CI: 0.216-0.176) for codon 347. In men and women there was no association between the codon 360 polymorphism and total cholesterol or triglyceride levels. However, subjects carrying the 360His allele had low-density lipoprotein (LDL) cholesterol concentrations statistically lower than homozygotes for the 360Gln allele, even after further adjustment for sex, age, region, body mass index, and APOE polymorphism (p = 0.043). The less common allele at codon 347 (the 347Ser allele) was associated with increased LDL-cholesterol concentrations with a clear gene-dosage effect after multivariate adjustment (p = 0.029). Although these polymorphisms showed no heterogeneity by geographic region, the magnitude of the effect was higher in subjects from Aragón compared with the Comunidad Valenciana, suggesting a possible influence of the higher fat intake in Aragón. In the combined association analysis subjects with the 360Gln/347Ser pseudohaplotype had the highest LDL-cholesterol concentrations, supporting the antagonistic effect between the 360His and the 347Ser alleles on this trait.

Postprandial lipemia is modified by the presence of the polymorphism present in the exon 1 variant at the SR-BI gene locus

It has recently been reported that carriers of the less common allele at the scavenger receptor class B type I (SR-BI) exon 1 polymorphism are more susceptible to the presence of saturated fatty acid in the diet because of a greater increase in LDL cholesterol. Our aim was to determine if this polymorphism could also influence postprandial lipoprotein metabolism, because the SR-BI has been described as a possible mediator in the intestinal absorption of triacylglycerols. Forty-seven normolipidemic volunteers who were homozygous for the E3 allele at the APOE gene were selected [37 homozygous for the common genotype (1/1) at the SR-BI exon 1 polymorphism and 10 heterozygous (1/2)]. They were given a fat-rich meal containing 1 g fat and 7 mg cholesterol per kg body weight and vitamin A 60,000 IU/m2 body surface. Fat accounted for 60% of calories, and protein and carbohydrates accounted for 15% and 25% of energy respectively. Blood samples were taken at time 0, every 1 h until 6 h, and every 2.5 h until 11 h. Total cholesterol and triacylglycerols in plasma, and cholesterol, triacylglycerols and retinyl palmitate in triacylglycerol-rich lipoproteins (large and small triacylglycerol-rich lipoproteins) were determined. Postprandial responses for triacylglycerols and retinyl palmitate in small triacylglycerol-rich lipoproteins were higher in 1/1 individuals than in 1/2 individuals. No other significant differences were noted. Our data show that the presence of the genotype 1/2 is associated with a lower postprandial lipemic response.

A Mediterranean and a high-carbohydrate diet improve glucose metabolism in healthy young persons

AIMS/HYPOTHESIS

Insulin resistance usually precedes the diagnosis of Type II (non-insulin-dependent) diabetes mellitus. However, in most patients, the clinical expression of the disease could be prevented by dietary and lifestyle changes. We investigated the effects of a diet enriched in monounsaturated fatty acids (Mediterranean diet) and a low fat, high-carbohydrate diet on in vivo and in vitro glucose metabolism in 59 young subjects (30 men and 29 women).

METHODS

We carried out an intervention dietary study with a saturated fat phase and two randomized-crossover dietary periods: a high-carbohydrate diet and a Mediterranean diet for 28 days each. We analysed the plasma lipoproteins fractions, free fatty acids, insulin sensitivity and glucose uptake in isolated monocytes at the end of the three dietary periods.

RESULTS

In comparison to the saturated fat diet, the CHO and Mediterranean diets induced a decrease of LDL-cholesterol (p < 0.001) and HDL-cholesterol (p < 0.001). Steady-state plasma glucose decreased (p = 0.023) and basal and insulin-stimulated 2-deoxiglucose uptake in peripheral monocytes increased in both diets (CHO and Mediterranean), (p = 0.007) indicating an improvement in insulin sensitivity. Fasting free fatty acids plasma values were correlated positively with steady state plasma glucose (r = 0.45; p < 0.0001). In addition, there was an inverse correlation between the mean glucose of the steady state plasma glucose period and logarithmic values of basal (r = -0.34; p = 0.003) and insulin stimulated glucose uptake in monocytes (r = -0.32; p = 0.006).

CONCLUSION/INTERPRETATION

Isocaloric substitution of carbohydrates and monounsaturated fatty acids for saturated fatty acids improved insulin sensitivity in vivo and in vitro, with an increase in glucose disposal. Both diets are an adequate alternatives for improving glucose metabolism in healthy young men and women.

Physical activity modulates the combined effect of a common variant of the lipoprotein lipase gene and smoking on serum triglyceride levels and high-density lipoprotein cholesterol in men

Physical activity has been identified as a protective factor against the occurrence and progression of coronary heart disease. The lipoprotein lipase (LPL) HindIII polymorphism has been associated with changes in triglyceride and high density lipoprotein (HDL)-cholesterol levels. We have investigated whether the association between the LPL HindIII genetic polymorphism and lipid levels is modified by physical activity. We have also tested the hypothesis that physical activity may interact with smoking and the LPL HindIII polymorphism to determine an individual's plasma lipid concentrations. A total of 520 men were selected from a representative sample used in a population study conducted in Gerona, Spain. The median value (291 kcal/day) of energy expenditure in leisure-time physical activity of the studied sample was selected as a cut-off to define sedentary or active subjects. Serum HDL-cholesterol was positively and significantly associated with the amount of daily energy expenditure in physical activity, whereas inverse associations were seen between physical activity and triglyceride concentration and with the triglyceride to HDL-cholesterol ratio. These effects were consistent across LPL HindIII genotypes. There was a statistically significant interaction between LPL genotype and smoking on lipid concentrations. No statistically significant differences were observed in lipid levels of active or sedentary non-smokers between H- carriers and H+H+ homozygotes for the LPL HindIII polymorphism. In smokers, sedentary H+H+ homozygotes showed significantly higher triglyceride and lower HDL-cholesterol concentrations than sedentary H- carriers. These differences were smaller and not statistically significant when lipid values of active H+H+ homozygotes were compared with active H- carriers. Among all subgroups, sedentary smokers with the H+H+ genotype had the most adverse lipid profile, which was considerably less adverse in H+H+ smokers who were physically active. These findings suggest that the presence of the H+H+ genotype has a deleterious effect on lipid profile in an adverse environment such as smoking, and that the expenditure of more than 291 kcal/day in physical activity attenuates this effect.

Mediterranean and low-fat diets improve endothelial function in hypercholesterolemic men

BACKGROUND

The regulatory function of the endothelium is altered in hypercholesterolemia, and the subsequent endothelial dysfunction plays a central role in the development of atherosclerosis.

OBJECTIVE

To determine whether endothelial function in hypercholesterolemic patients is affected by replacing a saturated fat-enriched diet with a low-fat, low-saturated fat diet (the U.S. National Cholesterol Education Program stage 1 [NCEP-1] diet) or a diet rich in monounsaturated fat (such as that common in Mediterranean countries).

DESIGN

Intervention dietary study with a baseline phase and two randomized crossover dietary periods.

SETTING

Hospital Universitario Reina Sofía, Córdoba, Spain.

PATIENTS

22 hypercholesterolemic men.

INTERVENTION

Patients followed a diet high in saturated fat, then were assigned in a crossover design to the NCEP-1 diet or a Mediterranean diet. Each dietary period lasted 28 days.

MEASUREMENTS

Plasma P-selectin levels, lipid concentrations, and endothelial function.

RESULTS

Compared with the saturated fat diet, flow-mediated dilatation increased during the Mediterranean diet but not during the NCEP-1 diet. In addition, levels of plasma cholesterol, low-density lipoprotein cholesterol, apolipoprotein B, and P-selectin decreased during the NCEP-1 and Mediterranean diets.

CONCLUSION

In hypercholesterolemic men, diets low in fat (especially saturated fat) and diets rich in monounsaturated fats improve endothelial function.

Association between the TaqIB polymorphism in the cholesteryl ester transfer protein gene locus and plasma lipoprotein levels in familial hypercholesterolemia

Cholesteryl ester transfer protein (CETP) facilitates the exchange of triglycerides (TG) and cholesteryl ester between lipoprotein particles. Subjects with familial hypercholesterolemia (FH) have been reported to have higher CETP activities, which could contribute to the lower high-density lipoprotein-cholesterol (HDL-C) levels and increased cardiovascular risk observed in some of these patients. Several polymorphisms have been reported in the CETP locus; the common TaqlB polymorphism is associated, in normolipidemic subjects, with decreased CETP activity and levels and with increased HDL-C levels. No data is available on the influence of this polymorphism in FH subjects. We have examined the TaqIB polymorphism in a group of 101 FH heterozygotes from Valencia, Spain. We have observed a frequency of 0.43 for the B2 allele, similar to those reported in the general population. Based on analysis of variance (ANOVA), we found significant associations between the presence of the B2 allele and increased plasma HDL-C (P <.04) and apolipoprotein A-I (apoA-I) levels (P <.01). An opposite association was observed for low-density lipoprotein-cholesterol (LDL-C) levels, with the B2/B2 subjects having lower levels than B1/B1 and B1/B2 subjects. The plasma apoB levels followed the same trend as those for LDL-C. In addition, the response to a National Cholesterol Education Program (NCEP)-I diet was studied in 77 of these subjects. The TaqlB polymorphism did not have a significant effect over the individual dietary response for any of the variables examined, as demonstrated by the lack of significant gene by diet interactions. In summary, the CETP TaqlB polymorphism is associated with a less atherogenic lipid profile, consisting of lower LDL-C, higher HDL-C levels, and a lower LDL-C/HDL-C ratio in heterozygous FH subjects. Moreover, the B2 allele was associated with a lower appearance of arcus cornealis, xanthomata, and clinical arteriosclerotic disease in these subjects.

Gene-diet interactions and plasma lipoproteins: role of apolipoprotein E and habitual saturated fat intake

To test whether plasma lipoprotein levels and low density lipoprotein (LDL) particle size are modulated by an interaction between habitual saturated fat intake and apolipoprotein E (APOE) genotype, we studied 420 randomly selected free-living Costa Ricans. The APOE allele frequencies were 0.03 for APOE2, 0.91 for APOE3, and 0.06 for APOE4. The median saturated fat intake, 11% of energy, was used to divide the population into two groups, LOW-SAT (mean intake 8.6% energy) represents those below median intake, and HIGH-SAT (mean intake 13.5%) represents those above median intake. Significant interactions between APOE genotype and diet were found for VLDL (P = 0.03) and HDL cholesterol (P = 0.02). Higher saturated fat intake was associated with higher VLDL cholesterol (+29%) and lower HDL cholesterol (-22%) in APOE2 carriers, while the opposite association was observed in APOE4 carriers (-31% for VLDL cholesterol and +10% for HDL cholesterol). Higher saturated fat intake was associated with smaller LDL particles (-2%, P < 0.05) in APOE2 carriers, and larger LDL particles (+2%, P < 0.05) in APOE4 carriers, but the gene-diet interaction was not statistically significant (P = 0.09). Higher saturated fat intake was associated with higher LDL cholesterol in all genotypes (mean +/- SEM, LOW-SAT 2.61 +/- 0.05 vs. HIGH-SAT 2.84 +/- 0.05 mmol/L, P = 0.009). These data suggest that the APOE2 allele could modulate the effect of habitual saturated fat on VLDL cholesterol and HDL cholesterol in a population with an average habitual total fat intake of less than 30%.

Homocysteine and the MTHFR 677C-->T allele in premature coronary artery disease. Case control and family studies

BACKGROUND

The aim of this work was to evaluate the role of homocysteine, and the MTHFR 677C-->T allele as risk factors for premature coronary artery disease and to analyse the inheritance of this metabolic disorder.

MATERIAL AND METHODS

Case-control and family studies were performed in a sample of 76 male patients (age < 55), 95 age-matched controls and 89 patients' offspring. Plasma total homocysteine concentrations, its nutritional determinants and the frequency of the MTHFR 677C-->T allele were measured, in addition to conventional risk factors.

RESULTS

Mild hyperhomocysteinemia (above the 90th percentile of the control group) was seen in 22.4% of patients (P = 0.02) and was an independent predictor of premature coronary artery disease (odds ratio of 3.2). The frequencies of the 677T allele in patients and controls were 0.37 and 0.36 and those of the TT genotype were 0.15 and 0.14, respectively. Homozygosity for the 677T allele was associated with significantly higher homocysteine values (P < 0.00001). Among TT patients, 64% had mild hyperhomocysteinemia, as compared to 23% of TT controls. Mild hyperhomocysteinemia showed a strong hereditary component, as 36% of patients' offspring had homocysteine levels above the age-adjusted 90th percentile compared to only 13% of patients' spouses. Among children with the TT genotype, the proportion raised to 83% (P < 0.001).

CONCLUSION

In this Spanish population, mild hyperhomocysteinemia is associated with the risk of premature coronary artery disease and is highly prevalent in offspring of patients with this condition. The MTHFR TT genotype is associated with hyperhomocysteinemia, but not with coronary artery disease.

Association of TaqIB polymorphism in the cholesteryl ester transfer protein gene with plasma lipid levels in a healthy Spanish population

Genetic variants at the cholesteryl ester transfer protein (CETP) locus have been associated with CETP activity and mass, as well as plasma high density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I levels. We have examined allele frequencies and lipid associations for the common CETP TaqIB polymorphism in a sample of 514 healthy subjects (231 men, mean age 37.4 years, and 283 women, mean age 35.7 years) residing in Valencia (Spain). The frequency of the less common TaqIB2 allele (0.351; 95% CI: 0.322-0. 380) was significantly lower than those reported for Northern European populations. Consistent with previous studies, we found a significant association of the TaqIB polymorphism with HDL-C levels. Homozygotes for the B1 allele had lower HDL-C levels than subjects carrying the B2 allele (P trend<0.001 and 0.002, for men and women, respectively). No statistically significant genotype effects were observed for any of the other lipid measures. Multivariate models including TaqIB genotype, body mass index, smoking, alcohol, physical activity, marital status and education were fitted to predict HDL-C levels. The TaqIB polymorphism was consistently an independent predictor of HDL-C levels (P<0.001), and explained 5.8% of its variance. To evaluate gene-environmental interactions, first order interaction terms were tested into the multivariate model. No statistically significant interactions between the TaqIB genotypes and smoking, alcohol, physical activity or education were detected. In conclusion, we observed a significant association of the TaqIB polymorphism with HDL-C levels, which remained consistent across different levels of behavioral factors. Moreover, we found that the TaqIB2 allele frequency was lower in our sample than in other European populations, which could be a contributing factor to the unexpectedly high prevalence of coronary heart disease observed in the region of Valencia.

Low-fat and high-monounsaturated fatty acid diets decrease plasma cholesterol ester transfer protein concentrations in young, healthy, normolipemic men

BACKGROUND

Cholesterol ester transfer protein (CETP) mediates the transfer of cholesteryl esters from HDL to apolipoprotein (apo) B-containing lipoproteins. The possible atherogenic role of this protein is controversial. Diet may influence plasma CETP concentrations.

OBJECTIVE

The objective was to determine whether the changes in plasma lipids observed after consumption of 2 lipid-lowering diets are associated with changes in plasma CETP concentrations.

DESIGN

: We studied 41 healthy, normolipidemic men over 3 consecutive 4-wk dietary periods: a saturated fatty acid-rich diet (SFA diet: 38% fat, 20% saturated fat), a National Cholesterol Education Program Step I diet (NCEP Step I diet: 28% fat, 10% saturated fat), and a monounsaturated fatty acid-rich diet (MUFA diet: 38% fat, 22% monounsaturated fat). Cholesterol content (27.5 mg/MJ) was kept constant during the 3 periods. Plasma concentrations of total, LDL, and HDL cholesterol; triacylglycerol; apo A-I and B; and CETP were measured at the end of each dietary period.

RESULTS

Compared with the SFA diet, both lipid-lowering diets significantly decreased plasma total and LDL cholesterol, apo B, and CETP. Only the NCEP Step I diet lowered plasma HDL cholesterol. Positive, significant correlations were found between plasma CETP and total (r = 0.3868, P < 0.0001) and LDL (r = 0.4454, P < 0.0001) cholesterol and also between changes in CETP concentrations and those of total (r = 0.4543, P < 0.0001) and LDL (r = 0.4554, P < 0.0001) cholesterol.

CONCLUSIONS

The isoenergetic substitution of a high-saturated fatty acid diet with an NCEP Step I or a high-monounsaturated fatty acid diet decreases plasma CETP concentrations.

Effect of apolipoprotein E genotype on lipid levels and response to diet in familial hypercholesterolemia

The response of plasma lipids to dietary fat and cholesterol is partly genetically controlled. Apolipoprotein (Apo) E polymorphism has been shown to influence basal plasma lipid levels and the response to dietary changes in normolipidemic individuals. In general, subjects carrying the E4 allele have higher basal total and low density lipoprotein cholesterol (LDL-C) plasma levels and show an increased LDL-C response to dietary manipulation. The response to diet in subjects with familial hypercholesterolemia (FH) is also variable, but the influence of apo E genotypes on their dietary response has received little attention. We studied such influence on the lipid response to the National Cholesterol Education Program type I (NCEP-I) diet in 69 FH heterozygotes (44 women and 25 men). Subjects were studied at baseline (after consuming for 1 month a diet with 35% fat [10% saturated] and 300 mg cholesterol) and after 3 months of consuming a low-fat diet. No sex-related differences were found, and results were combined for men and women. The frequency distribution of apo E alleles was similar to that described in the general Spanish population: 0.0724 for the E2 allele, 0.0724 for E4 and 0.8551 for E3. Baseline plasma lipid and lipoprotein values were not influenced by apo E genotype. The response to the NCEP-I diet was similar in all subjects and no apoE allele-related differences were identified. As in non-FH subjects, there was a nonsignificant trend towards greater LDL-C lowering in E4 (-19.3%) than in E3 (-18.2%), and E2 (-16.6%) carriers. This finding supports the hypothesis that the impact of genetic defects at the low density lipoprotein receptor (LDLR) locus in FH subjects prevails over any influence on the part of ApoE polymorphism.

Comparison of an oleic acid enriched-diet vs NCEP-I diet on LDL susceptibility to oxidative modifications

OBJECTIVE

The objective of this trial was to compare the effect on the susceptibility of plasma Low Density Lipoprotein (LDL) to oxidative modifications of consumption of two oleic rich diets, prepared with two different plant oils, virgin olive oil (OL)1 and refined high monounsaturated fatty acids (MUFA sunflower oil (SU)), with the susceptibility of plasma LDL to oxidation after an National Cholesterol Education Program step 1 (NCEP-I) phase diet.

DESIGN

A randomized crossover design.

SUBJECTS AND INTERVENTIONS

Twenty-two healthy normolipidemic young males consumed an NCEP-I diet for a 4-week period. Subjects were then assigned to two diets each of 4-weeks duration. Group one was placed on an olive oil enriched diet (40% fat, 22% MUFA) followed by a 4-week period of a MUFA diet enriched in sunflower oil (40% fat, 22% MUFA). In group two, the order of the diets was reversed.

RESULTS

Both MUFA diets induced a decrease in saturated (14:0, 16:0, and 18:0) and an increase in monounsaturated and polyunsaturated n-6 (18:2, 20:3, and 20:5) plasma LDL-phospholipid fatty acids, compared to the NCEP-I diet (P<0.01). No significant differences in lag times were observed between the olive oil and the NCEP-I diet periods. However there was a greater inhibition time (P<0.001) when subjects consumed the MUFA rich sunflower oil diet compared to the NCEP-I diet. These differences were probably related to the relative enrichment of plasma LDL particles in alpha-tocopherol due to the high vitamin E content of the MUFA-rich sunflower oil. Indeed, the alpha-tocopherol content was positively correlated with lag time (r=0.338; P<0.008).

CONCLUSION

Our findings suggest that changes in plasma LDL alpha-tocopherol content with practical solid-food diets can decrease its susceptibility to oxidation.

SPONSORSHIP

This work has been supported by grants from the Investigaciones de la Seguridad Social (FIS 92/0182, to Francisco Pérez Jiménez); and from Koype Co, Andújar, Jaén, Spain. European Journal of Clinical Nutrition (2000) 54, 61-67

[Association of blood uric acid with other cardiovascular risk factors in the male working population in Valencia]

BACKGROUND

Serum uric acid has been reported to be a risk factor for cardiovascular disease (CVD). The objective of the present work was to determine the prevalence of hyperuricemia in a large size sample of a healthy male population, as well as the association between uric acid and other cardiovascular risk factors.

PATIENTS AND METHODS

A cross-sectional study was conducted in a randomly selected sample of 1,564 healthy men in Valencia (Spain), aged 20-67 years, working in the automobile industry. Serum values of uric acid, cholesterol, and glucose were obtained, as well as blood pressure and body mass index measurements. An assessment was made of socio-economic data, drug therapy, and smoking.

RESULTS

The overall prevalence of hyperuricemia was 5.10%; it increased with age. A marked increase (p < 0.01) of hyperuricemic individuals was observed with increased prevalence of other cardiovascular risk factors (from 1.8% with hyperuricemia alone up to 28% among individuals with four simultaneous risk factors). By means of a multivariate logistic regression analysis, the OR of hyperuricemia associated with each factor were calculated: increased serum glucose was the variable with a stronger association (OR: 2.69; 95%CI: 1.21-5.99), obesity ranking next (OR: 2.50; 95%CI: 1.42-4.49). Statistically significant associations were also observed for increased serum cholesterol, increased blood pressure, and smoking.

CONCLUSIONS

The prevalence of hyperuricemia varies with the simultaneous presence of other classical cardiovascular risk factors. Even in this healthy mediterranean population, uric acid is significantly associated with several components in the plurimetabolic syndrome.

Circulating levels of endothelial function are modulated by dietary monounsaturated fat

BACKGROUND

For the most part, the benefits of monounsaturated-rich diets (MUFA-diet) have been related to their action on plasma lipid levels. However other non-lipidic effects could also be involved in their protective effects. One of these involves the decrease in plasma levels of plasminogen activator inhibitor type 1 (PAI-1), the main inhibitor of fibrinolysis. Given that the PAI-1 is of endothelial origin, one hypothesis is that the MUFA-diet could protect against CHD by modulating some endothelial components.

METHODS AND RESULTS

Healthy male subjects (n = 25) received three different consecutive diets, each lasting 28 days: a low fat NCEP-I-diet, with 28% calories as fat, 10% saturated fat (SAT), 12% monounsaturated (MUFA) and 6% polyunsaturated (PUFA); a MUFA-diet, with 38% calories as fat, 10% SAT, 22% MUFA and 6% PUFA; and a SAT rich-diet (SAT-diet), with 38% calories as fat, 20% SAT, 12% MUFA and 6% PUFA. After each dietary period, the plasma lipid profile was determined, including total cholesterol, HDL cholesterol, LDL cholesterol, total triglyceride, apo A1, apo B plasma levels and conjugated diene formation, after incubation of LDL particles with Cu 5 microM/l. Endothelial products measured in plasma were von Willebrand factor (vWF), E-selectin, Thrombomodulin and Tissue Factor Pathway Inhibitor (TFPI) levels. We observed a decrease in vWF, PAI-1 and TFPI plasma levels and an increase in lag time of conjugated diene formation after the MUFA-diet. There was a positive correlation between the decreases in TFPI and vWF and the changes in total cholesterol, LDL-C, apo B plasma levels. The decrease in TFPI was negatively correlated with the increase in lag time of conjugated diene formation. PAI-1 plasma levels were positively correlated with total cholesterol, LDL-C and triglycerides and negatively correlated with HDL-C.

CONCLUSIONS

Consumption of a Mediterranean-type MUFA-diet produces a decrease in plasma levels of vWF, TFPI and PAI-1 plasma levels in young healthy males. Given that these substances are of endothelial origin, one could suggest that the MUFA of the diet has a beneficial effect on endothelial function resulting in protective changes against thrombogenesis.

Effects of different dietary cholesterol concentrations on lipoprotein plasma concentrations and on cholesterol efflux from Fu5AH cells

BACKGROUND

The fatty acid composition of the diet can modulate the effect of dietary cholesterol on plasma lipoproteins. However, HDL composition and its capacity to promote cholesterol efflux can be influenced by the diet.

OBJECTIVE

Modifications in plasma lipids and in the capacity of serum to stimulate the cholesterol efflux induced by a low-fat diet [National Cholesterol Education Program (NCEP) Step I diet], by a monounsaturated fatty acid (MUFA)-rich diet, and by addition of cholesterol to both diets was studied.

DESIGN

Fifteen young, healthy men followed 2 NCEP Step I diets (<30% of fat as energy, with <10% saturated fat and 14% MUFAs) for 24 d, providing 0.027 or 0.068 mg cholesterol x kJ(-1) x d(-1), and 2 oleic acid-enriched diets (38% of energy as fat, with 24% MUFAs) providing the same amount of dietary cholesterol as the NCEP Step I diets.

RESULTS

Total cholesterol, LDL cholesterol, apolipoprotein (apo) B, and apo A-I concentrations decreased after the NCEP Step I and MUFA diets compared with the usual diet. HDL cholesterol also decreased after the NCEP Step I diet. Total:HDL cholesterol, apo B, and apo B:apo A-I were lower after the MUFA diets than after the NCEP Step I diets. There were no significant differences between the lipid profiles obtained after the NCEP Step I and MUFA diets were enriched with cholesterol. The capacity of serum to promote cholesterol efflux was significantly higher after the cholesterol-enriched NCEP Step I diet than after the NCEP Step I diet.

CONCLUSIONS

The MUFA diet induced a better lipid profile than the NCEP Step I diet; however, the increase in the cholesterol content of both diets produced similar plasma lipid changes. The cholesterol in the NCEP Step I diet increased the cholesterol efflux induced by total serum.

The SstI polymorphism of the apolipoprotein C-III gene determines the insulin response to an oral-glucose-tolerance test after consumption of a diet rich in saturated fats

The S2 allele of the SstI polymorphism of the apolipoprotein (apo) C-III gene has been associated with elevated triacylglycerol concentrations, high blood pressure, and increased risk of coronary artery disease, all of which are characteristic of an insulin-resistant state. To study the effect of this mutation on carbohydrate metabolism in healthy persons, we gave 41 male subjects 3 consecutive diets. The first was rich in saturated fat [15% protein, 47% carbohydrate, 38% fat (20% saturated)], the second was a National Cholesterol Education Program Step 1 diet [15% protein, 57% carbohydrate, 28% fat (< 10% saturated)], and the last was rich in monounsaturated fat [15% protein, 47% carbohydrate, 38% fat (22% monounsaturated, < 10% saturated)]. At the end of each dietary period, subjects received an oral-glucose-tolerance test (OGTT). Apo C-III genotype significantly affected basal glucose concentrations (P < 0.045) and insulin concentrations after the OGTT (P < 0.012). APOC3*S1/APOC3*S2 subjects (n = 13) had higher insulin concentrations after the OGTT than APOC3*S1/APOC3*S1 subjects (n = 28) in the 3 periods (diet 1: P < 0.0004; diet 2: P < 0.01; diet 3: P < 0.008). Multiple regression analysis showed that this polymorphism predicted the insulin response to the OGTT (P < 0.031) and the difference between basal insulin concentrations and insulin concentrations after the OGTT (P < 0.002) with the saturated fat diet. In summary, our results suggest that the mutation in the apo C-III gene affects insulin response to an OGTT, which could result in reduced sensitivity to insulin, especially when persons consume diets rich in saturated fat.

Effects of dietary fat saturation on eicosanoid production, platelet aggregation and blood pressure

The effects of dietary fat saturation on eicosanoid urinary excretion, platelet aggregation (PA) and blood pressure (BP) were studied in 42 healthy subjects. They consumed four consecutive diets differing in their fat saturation [saturated (SFA); monounsaturated (MUFA); polyunsaturated n-6 (PUFA n-6); and polyunsaturated n-6/n-3, (PUFA n-3)]. Each diet period lasted 5 weeks. There were no differences in 24-h 2,3-dinor-6- keto-prostaglandin F1 alpha excretion among dietary periods. A significant effect was noted regarding the excretion of 11-dehydro-thromboxane B2 (P < 0.0001). During the PUFA n-6 phase the excretion was significantly higher than during SFA and MUFA periods. Dietary fatty acid composition had a significant effect on ADP (1 mumolL-1) and collagen (2 mgL-1) induced PA. Dietary fat also had a significant effect on systolic and diastolic blood pressure (P < 0.0001). Both were significantly higher during the SFA period than during the other three periods. Our findings suggest that changes in dietary fatty acids may have mild, but significant, effects on eicosanoid production, platelet aggregation and blood pressure.

Urbanization elicits a more atherogenic lipoprotein profile in carriers of the apolipoprotein A-IV-2 allele than in A-IV-1 homozygotes

Coronary heart disease (CHD) is increasing in developing countries, particularly in urban areas. The impact of urbanization and apolipoprotein (apo) A-IV genetic polymorphism on plasma lipoproteins was studied in 222 men and 236 women from rural and urban Costa Rica. The apoA-IV allele frequencies were 0.937 for apoA-IV-1 and 0.062 for apoA-IV-2, Significant interactions between the apoA-IV polymorphism and area of residence (rural versus urban) were detected for HDL cholesterol (P = .003), apoA-I (P = .05), LDL particle size (P = .01), and LDL/HDL cholesterol ratio (P = .005). Urban compared with rural carriers of the apoA-IV-2 allele had significantly lower plasma HDL cholesterol (0.95 versus 1.17 mmol/L) and apoA-I (980 versus 1140 mg/L), a significantly higher LDL/HDL cholesterol ratio (3.35 versus 2.39), and significantly smaller LDL particles (258 versus 263 A). In contrast, no significant rural-urban differences for these parameters were found in apoA-IV-1 homozygotes. Regardless of their apoA-IV phenotype, urban residents consumed more saturated fat (P = .02) and smoked more cigarettes per day (P = .03) than rural residents. A significant interaction between saturated fat intake and apoA-IV phenotype was found for HDL cholesterol (P < .0003) and LDL/HDL cholesterol ratio (P < .003). Increased saturated fat intake (13.6% versus 8.6% of calories) was significantly associated with 6% higher HDL cholesterol and no change (0.7%) in LDL/HDL cholesterol ratio in apoA-IV-1 homozygotes and with 19% lower HDL cholesterol and 37% higher LDL/HDL cholesterol ratio among carriers of the apoA-IV-2 allele. Smokers (> or = 1 cigarette per day) had significantly lower HDL cholesterol (P < .005) and apoA-I (P < .01) concentrations than nonsmokers (< 1 cigarette per day), particularly among carriers of the apoA-IV-2 allele (-19% and -13%) compared with apoA-IV-1 (-4% for both). After taking these lifestyle characteristics into account, the areas of residence by phenotype interactions for plasma lipoprotein concentrations were no longer statistically significant. Lifestyles associated with an urban environment, such as increased smoking and saturated fat intake, elicit a more adverse plasma lipoprotein profile among Costa Rican carriers of the apoA-IV-2 allele than in apoA-IV-1 homozygotes. Therefore, under the conditions studied, persons with the apoA-IV-2 allele may be more susceptible to CHD.

[Pravastatin increases the activity pf the LDL receptors in lymphocytes of individuals with heterozygous familial hypercholesterolemia]

An investigation was conducted on the effects of pravastatin, an inhibitor of the HMG CoA reductase, on lipoproteins concentrations and degradation of LDL (low density lipoproteins) in 14 patients with familial hypercholesterolemia (FH). Therapy with pravastatin for twelve weeks, 20 mg every 12 hours, and a low fat (30% calories) and cholesterol (less than 300 mg/daily) diet decreased serum concentrations of LDL cholesterol and apolipoprotein B by 35.5% and 24%, respectively (p < 0.001 for both parameters). On the other hand, apolipoprotein A-1 concentrations increased by 15.1% (p < 0.05) and HDL cholesterol (high density lipoproteins) by 6.8%; concentrations of apolipoprotein A-II did not change. LDL degradation in peripheral lymphocytes increased by 41.3% (p < 0.05) and a correlation was observed (p < 0.05) between percentage of LDL degradation and percentage in the LDL cholesterol decrease. Likewise, a positive trend (p = 0.057) was observed between increases in LDL degradation and aging. These findings indicate that pravastatin favorably influences the lipoprotein profile and that this effect is mediated, at least partly, by an increase in cellular capacity of LDL degradation.

Apo E variants in patients with type III hyperlipoproteinemia

Type III hyperlipoproteinemia (HLP III) is characterized by the reduced catabolism and accumulation of chylomicron and very low density lipoprotein (VLDL) remnants. Most HLP III patients are homozygous for the apolipoprotein E2 (Cys112, Cys158) allele; however, several other mutations at this gene locus have been associated with this HLP. In order to assess the presence of rare apo E variants in our population, we have examined apo E phenotypes by isoelectric focusing (IEF) and genotypes by restriction enzyme analysis of polymerase chain reaction (PCR) amplified DNA in 15 patients with HLP III. Lack of concordance between these two methods was observed in 11 subjects (73.3%). DNA sequencing analysis of the receptor binding domain of the apo E gene in the 11 HLP III patients with discrepancies demonstrated the presence of six carriers of the epsilon 3(Arg136-->Ser) allele and three carriers of the epsilon 2(Gly127-->Asp) allele. Five HLP III patients were apo E2/E2 using IEF, but only 2 of them were epsilon 2 homozygous using PCR. Two patients were E3/E3 homozygous with normal DNA sequence in the low density lipoprotein receptor binding domain of apo E. In conclusion, our results show that a number of different apo E genotypes are associated with HLP III in this population. More specifically, mutations at positions 127 and 136 might be frequent in Spain and occur in patients with HLP III.

Expression of apolipoprotein E in cholesterol-loaded macrophages of extrahepatic tissues during experimental hypercholesterolemia

To study the expression of extrahepatic apolipoprotein E (apoE) under hypercholesterolemic conditions, apoE mRNA levels were evaluated in 14 tissues of rabbits fed on a cholesterol rich diet and compared to age-matched control animals. In hypercholesterolemic rabbits apoE expression was significantly induced in adipose tissue, adrenals, aorta, lung and spleen. The increase in apoE mRNA levels in lung and spleen was associated with the presence of cholesterol-loaded macrophages. These cells were found to express high levels of apoE mRNA as demonstrated by in situ mRNA hybridization. Our results suggest that extrahepatic tissues would be partially responsible for the rise in serum apoE levels detected under hypercholesterolemic conditions.

The human hepatoma cell line, HepG2, secretes functional cholinesterase

Confluent monolayers of the human hepatoblastoma-derived cell line, HepG2, were incubated in serum-free medium. This medium was harvested and concentrated. Catalytic activity and immunoblotting of concentrated medium revealed the presence of a functional cholinesterase. This cell line may be an useful model for investigating the regulation and physiological role of the enzyme secreted by liver.

Differential effect of dietary fat saturation and cholesterol on hepatic apolipoprotein gene expression in rats

The effects of dietary cholesterol and fat saturation on hepatic apolipoprotein A-I, A-II, A-IV, B, C-I, C-III, E and LDL receptor mRNA levels were studied in male rats. Animals were maintained for 2 months on a high fat diet (40% w/w) containing 0.1% cholesterol. Two groups of control animals received either chow diet or chow plus 0.1% cholesterol, while experimental groups received as their fat supplement coconut, corn or olive oil. Olive oil fed animals had higher levels of hepatic apo A-I than the control cholesterol group (1.6 +/- 0.3 vs. 0.8 +/- 0.2). Apo E mRNA levels were 50% and 72% higher in animals consuming the saturated (coconut) and unsaturated (corn and olive) fat diet than the control cholesterol group. Apo B and apo C-I mRNA levels were not affected by the experimental conditions. Apo A-IV mRNA increased between 66% and 127% in groups in which cholesterol was present. LDL receptor mRNA increased 2 times in the corn fed group compared with the control groups. These results indicate that the expression of genes coding for products involved in lipoprotein metabolism have a differential susceptibility to dietary fat saturation and cholesterol.

Nucleotide sequences of the Macaca fascicularis apolipoprotein C-III and A-IV genes

The cynomolgus monkey (Macaca fascicularis) apolipoprotein C-III and apolipoprotein A-IV genes have been isolated from a cynomolgus genomic DNA library and completely sequenced. These genes span 3.1 and 2.8 kilobases (kb), respectively. Apolipoprotein C-III gene is interrupted by three intervening sequences of 613, 135 and 1699 bp, respectively. The open reading frame encodes a protein of 99 amino acids which is 87% similar to the human. The cynomolgus mature protein is 79 residues long. Thr-74 is also present what might allow the formation of O-glycosidic linkage observed in the human protein. Apolipoprotein A-IV gene consist of two intervening sequences of 352 and 774 bp, respectively. The open reading frame encodes a protein of 429 amino acids which is 87% similar to the human. The cynomolgus mature protein is 409 residues long, 33 amino acids longer than the human, due to an insertion of 33 residues in its COOH-terminal region. This insertion is mainly composed of glutamine and glutamic acid, which confers cynomolgus apolipoprotein a higher hydrophilicity.

Molecular cloning and sequence of the cynomolgus monkey apolipoprotein A-II gene

A clone containing the coding region for cynomolgus monkey (Macaca fascicularis) apolipoprotein A-II has been isolated from a cynomolgus genomic DNA library. The gene spans 1.4 kilobases (kb). The complete nucleic acid sequence of the apolipoprotein A-II gene has been determined, establishing that the gene is interrupted by three intervening sequences of 170, 273 and 394 bp, respectively. The open reading frame encodes a protein of 100 amino acids, and shows 94% sequence similarity with its human equivalent. Both apolipoproteins have identical signal peptide. A noticeable feature is the substitution of mature human Cys-6 for Ser. This change explains the existence of cynomolgus apolipoprotein A-II as a monomer and may have important consequences in the kinetics of this apolipoprotein.

Hypercholesterolemia induces differential expression of rabbit apolipoprotein A and C genes

We have compared steady-state mRNA levels of apolipoproteins AI, AII, AIV, CI, CII and CIII in liver and small intestine of rabbits fed on a cholesterol-rich diet for up to 16 weeks. Apolipoprotein (apo) AIV mRNA was detected in both liver and small intestine, while apo AII was not detected in either organ. Apo CI, apo CII and apo CIII were expressed only in liver and apo AI mRNA was detected only in small intestine. In small intestine, apo AIV and apo AI mRNA levels increased to a maximum at the 4th and 12th week of treatment, respectively. In liver there was a parallel increase in the mRNA levels of apo AIV, apo CI, apo CII and apo CIII, with maximum levels after 4 weeks of treatment. A 3-fold increase was found in apo CII and apo CIII hepatic transcription rates between hypercholesterolemic and control rabbits after 4 weeks of treatment, no longer detectable after 8 weeks. However, no changes were found in apo AIV and apo CI transcription rates. Changes in apolipoprotein mRNA levels were accompanied by changes in plasma lipoprotein levels. Overall, these changes correlate well with the variations detected in the expression of the different apolipoprotein genes. Our results indicate that dietary cholesterol plays an important role in the regulation of these genes and that this regulation is tissue dependent.

Foam cells from aorta and spleen overexpress apolipoprotein E in the absence of hypercholesterolemia

We have studied Apo E expression in atherosclerotic lesions and spleens in rabbits after a cholesterol-rich diet is discontinued and plasma cholesterol levels return to normal values. After 16 weeks, foam cells are still present in the atherosclerotic lesions and Apo E expression persists restricted solely to the lesion as ascertained by in situ RNA hybridization and northern blot. Apo E expression is induced in spleens of hypercholesterolemic rabbits. However Apo E mRNA levels decrease in this organ parallel to the disappearance of lipid loaded macrophages. These results of in vivo studies indicate that Apo E overexpression in foam cells does not depend on high serum cholesterol levels, but is a characteristic of macrophages that have acquired the foam cell phenotype.

Induction of apolipoprotein E gene expression in human and experimental atherosclerotic lesions

Hypercholesterolemia and atherosclerosis were induced in New Zealand White rabbits by cholesterol feeding. Apolipoprotein E mRNA levels in livers were found to be slightly increased, as determined by Northern blots. Apolipoprotein E gene expression was dramatically induced in rabbit atherosclerotic aortas with respect to healthy aortas. However, apolipoprotein E mRNA levels in atherosclerotic aortas were low as compared with the hepatic mRNA levels of the same animals. Interestingly, we also found a significant increase in apolipoprotein E expression in human atheromata with respect to healthy aorta from the same individual. This is the first report on apo E gene induction in human atherosclerotic lesions.

Plasma lipids and apolipoproteins A and B in human pregnancy

A cross sectional study was carried out in 200 normal pregnant women between 8-40th weeks of gestation, 25 women during delivery and 25 women 6 weeks after delivery. Plasma and lipoprotein lipids were measured using standard procedures. Apolipoprotein A (Apo A) and Apolipoprotein B (Apo B), were measured by electroimmunoassay. Plasma levels of Apo A were elevated in pregnant women but the elevations were not significant until 17-20 weeks of gestation. Apo A during pregnancy was significantly correlated (p less than 0.001) with high density lipoprotein cholesterol (HDL-C). The level of Apo B increased progressively during pregnancy and it was significantly correlated (p less than 0.001) with total cholesterol (TC), plasma triglycerides (TG) and phospholipids (PL). Apo A and Apo B levels returned to non pregnant values within the puerperium, whereas TC, TG and PL remained significantly elevated above controls (p less than 0.01) 6 weeks post partum.