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The objective of the study was to determine the prevalence of different forms of dyslipidemia in an urban population of Mexican adolescents. A cross-sectional study was conducted in 1846 students from 8 randomly selected public junior high schools in Mexico City. Anthropometry, blood pressure, and 12-hour fasting lipids and lipoproteins were measured. We studied 770 male and 1076 female adolescents (13.2 +/- 1 years). The most prevalent dyslipidemia was low high-density lipoprotein cholesterol (HDL-C) (<35 mg/dL) either combined with other abnormalities (17.5% for male and 12.9% for female subjects, P < .001) or isolated (13.5% and 9.6% for male and female subjects, respectively, P < .001). Obese subjects showed the highest prevalence of low HDL-C (47.2% for male and 34.4% for female subjects) and of high total cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG) (19.4%, 27.8%, and 36.1%, respectively, for male subjects; 9.8%, 13.1%, and 24.6%, respectively, for female subjects). Multiple regression analysis showed that waist circumference was negatively associated with HDL-C and positively associated with LDL-C and TG levels, whereas Tanner stages were negatively associated but sex was positively associated with total cholesterol, LDL-C, and TG concentrations. As in Mexican adults, low HDL-C and high TG levels were the most prevalent dyslipidemias. Increased blood lipids over long periods suggest that, as adults, these adolescents will be facing a higher risk for atherosclerosis.

Modulation by sex hormones of aortic reactivity in rats with the metabolic syndrome (MS) was investigated. The following groups of weanling male Wistar rats were used: control rats (C) received regular tap water while MS rats received 30% sucrose in their drinking water; both had rodent chow for 24 weeks. These two groups were further subdivided into the following four groups: intact (Int), castrated (Cas), castrated plus testosterone (T) and castrated plus estradiol (E). Vascular response of thoracic aortic rings to norepinephrine (NE), acetylcholine (ACh), indomethacin (Indo) and nitro-l-arginine-methyl ester (L-NAME) was investigated. Blood pressure (BP) and serum nitrates and nitrites were measured. BP and serum nitrates and nitrites were modified by castration and treatments with either T or E. Vasoconstriction in Int MS and Cas MS+T aortas was larger than in C and Cas C+T, respectively. Vasodilation in Int MS and Cas MS+T was reduced in comparison with C and Cas C+T, Cas MS and Cas MS+E. Indomethacin decreased vasoconstriction in all groups (P<0.002) but Int C and Cas C+T remained significantly smaller than Int MS and Cas MS+T. l-NAME in NE-contracted vessels induced a significant increase in vasoconstriction, except in Cas C+E rats; the responses of Int MS and Cas MS+T were significantly larger than in Int C and Cas C+T. The results suggest endothelial dysfunction in Int MS and Cas MS+T and a protective effect resulting from castration and castration plus E in MS animals, indicating a sex hormone influence.

Background: Small HDL particles have emerged as significant predictors of incident type 2 diabetes mellitus (T2DM) in adults with impaired glucose tolerance (IGT). However, no previous study has investigated HDL size in pediatric subjects with these clinical conditions., Methods: We studied the HDL size distribution by native polyacrilamide gradient gel electrophoresis in 106 overweight children, 47 with T2DM, 43 with normal glucose tolerance (NGT), 16 with IGT, and 39 healthy weight controls., Results: Diabetic children had significantly lower proportions of HDL2b and HDL2a, and higher proportions of HDL3b and HDL3c than the other 3 groups. Overweight subjects showed HDL size distributions similar to those of controls. However, insulin-resistant children had lower proportions of HDL2b, and HDL2a, and higher proportions of HDL3b when compared with the insulin-sensitive overweight subjects. Multiple linear regression analyses showed that homeostasis model assessment correlated inversely with HDL2b and HDL2a, and directly with HDL3b, while BMI was independently associated only with HDL3a., Conclusions: This study showed that HDL size distribution was shifted toward smaller particles in T2DM pediatric patients and in overweight children with insulin resistance, independent of their glucose tolerance status. Insulin resistance was the main factor associated with these HDL size abnormalities. This parameter could be useful as an early risk marker of incident diabetes and, probably, of coronary heart disease.

Background: Arthrospira maxima has been widely used for nutritional purposes. Additionally, A. maxima has shown immunomodulator, antiviral, antioxidant, vasomotor and hypolipidemic effects in laboratory and animal studies. A. maxima prevents fatty liver induced by either carbon tetrachloride (CCl4) or fructose-rich diet; however, the liver lipid composition in these models is not clearly known yet. The aim of this study was to evaluate the effects of A. maxima on the liver lipid profile in CCl4-induced steatohepatitis., Methods: A single sublethal, intraperitoneal dose of CCl4 was administered to male Wistar rats fed a diet with or without 5% A. maxima. Liver lipids: total lipids, triacylglycerols, total cholesterol, free fatty acids, and thiobarbituric acid reactive substances were assessed 24 and 48 h after injury with CCl4. Additionally, triacylglycerols, total cholesterol and aspartate aminotransferase were evaluated in blood., Results: Forty eight hours after CCl4 treatment, rats fed a diet without A. maxima had serum aspartate aminotransferase and liver triacylglycerols values that were, respectively, 2.2 and 1.4 times higher than those of animals receiving 5% A. maxima in their diet. The same pattern was observed for liver free fatty acids and thiobarbituric acid reactive substances. The groups fed a diet with A. maxima and treated with CCl4 showed a higher saturated fatty acid liver content than the groups without A. maxima in their diet. The percentage of unsaturated fatty acids increased 48 h after CCl4 treatment, but its value was 0.5 times lower in the group receiving A. maxima than in the group fed without A. maxima. In the liver, all animals receiving A. maxima showed a trend towards a lower percentage of unsaturated fatty acids, despite the mentioned increase 48 h after CCl4 treatment., Conclusions: The results suggest that, in the fatty liver induced by CCl4, the hepatoprotective effect of A. maxima involves (a) an antioxidant mechanism and (b) a lower unsaturation of the liver fatty acids. The preventive effect of A. maxima on the liver lipid changes induced by CCl4 could be partially explained by its antioxidant action and the ability to increase the synthesis/release of nitric oxide, but not by its soluble dietary fiber.

Purpose: To examine the prevalence of coronary risk factors in Mexican adolescents, and their relations to school type, gender, and residence in urban and rural areas., Methods: A cross-sectional survey was conducted in 3121 junior high school students, aged 12 to 16 years, attending urban schools (eight public, n = 1850, two private, n = 480) and three rural public (n = 791) schools. Weight, height, waist circumference, blood pressure, and fasting glucose and lipid-lipoprotein levels were measured. Tobacco smoking and physical activity were also ascertained. The prevalence rates of cardiovascular risk factors were determined by gender and school type., Results: Obesity, overweight, high blood pressure, cigarette smoking, and physical inactivity were higher for urban than rural adolescents. The prevalence of the low HDL-C level was exceedingly high in adolescents of three school types (> 30%) but particularly in male rural students (48.9%). Compared with rural students, high LDL-cholesterol was twice as high in private schoolchildren. The prevalence of impaired fasting glucose was .35% in the whole population and much higher in obese males (1.6%) and obese females (2.4%)., Conclusions: Our findings highlight an epidemic of coronary risk factors mainly in adolescents living in the urban area, suggesting the importance of environmental factors.

Background: Aortic rings with endothelium excised from fructose-fed obese rats develop more tension in response to phenylephrine and relax less in response to carbachol than corresponding rings from lean rats. This altered vascular reactivity is prevented when Spirulina maxima is added to the fructose-rich diet. In the present study the effects of a raw ethanolic extract of Spirulina maxima on the vasomotor responses of aorta rings from sucrose-fed obese hypertensive rats were analyzed., Methods: The experiments were performed on aorta rings from sucrose-fed obese male rats. For each experiment, a pair of rings from the same aorta (one with intact endothelium, the other without a functional endothelium) was used. In this study we analyzed, in vitro, the effects of the ethanolic extract of Spirulina maxima on the reactivity of the aortic rings to phenylephrine and to carbachol., Results: On rings with endothelium, the extract produced the following effects: a) a concentration-dependent (0.06-1.0 mg/mL) decrease of the contractile response to phenylephrine; b) a rightward shift and a decrease in maximal developed tension, of the concentration-response curve to phenylephrine; c) a concentration-dependent relaxation of phenylephrine-precontracted rings. These effects persisted in the presence of indomethacin but were prevented by L-NAME. The extract had no effect on the concentration-response curve of phenylephrine-precontracted rings to carbachol. On endothelium-denuded rings the extract caused a significant rightward shift of the concentration response curve to phenylephrine without any effect on maximal tension development., Conclusions: These results suggest that, in rings from obese rats, the extract, in addition to increasing the synthesis/release of NO, also inhibits the synthesis/release of a cyclooxygenase-dependent vasoconstrictor metabolite of arachidonic acid, which is increased in obesity.

Previous studies in the Mexican population have failed to show an effect of apolipoprotein E (APOE) polymorphism on the lipid profile. The purpose of the present study was to determine the frequencies of APOE phenotypes, and their influence on lipid and apolipoprotein levels in a random sample of Mexican adolescents living in Mexico City. APOE polymorphism, fasting insulin levels, lipid levels, and apolipoprotein levels were determined in 420 adolescents. We found a high frequency of APOE*3 subjects (89.5%) and a low frequency of APOE*2 (3.0%) and APOE*4 (7.5%) subjects. The APOE*4 subjects (including APOE 4,3 and APOE 4,4) showed the highest concentrations of total cholesterol, low-density lipoprotein cholesterol, and apoB and the lowest high-density lipoprotein cholesterol levels, whereas carriers of the APOE*2 allele (APOE 3,2 and APOE 2,2) had the lowest values for total and low-density lipoprotein cholesterol and the highest concentrations of high-density lipoprotein cholesterol. No significant differences in triglyceride and insulin levels among subjects with different APOE polymorphisms were observed. Unlike previous studies in the Mexican population, our results show that lipid and lipoprotein levels are under the influence of APOE polymorphism. As in whites, APOE*4 may be a cardiovascular risk factor in the Mexican population.

Objective: To examine low-density lipoprotein (LDL) size, LDL susceptibility to oxidation, and plasma insulin levels in children with systemic lupus erythematosus (SLE)., Methods: Fifty-nine SLE patients and 59 healthy, age-matched control subjects were studied. LDL size was determined by gradient gel electrophoresis. LDL oxidizability was assessed by lag time for conjugated diene formation during copper incubation. Plasma levels of fasting insulin, glucose, lipids, lipoproteins, apolipoproteins B and A-I, and fatty acids were also measured., Results: Compared with control subjects, SLE patients showed significantly higher plasma insulin levels and increased susceptibility of LDLs to oxidation. Patients with active disease were more likely than patients with inactive disease or control subjects to have the following lipid characteristics: small, dense LDL subclass, elevated total cholesterol levels, elevated LDL cholesterol levels, elevated triglyceride levels, and low levels of high-density lipoprotein cholesterol (HDL-C). Statistically significant direct correlations were observed between disease activity and triglyceride levels and between disease activity and lag time, whereas significant inverse correlations were found between disease activity and HDL-C levels and between disease activity and LDL size. Prednisone dosage explained only 15.6% of the variance in insulin levels., Conclusion: SLE patients have higher plasma insulin levels and increased LDL oxidizability compared with healthy control subjects. These abnormalities may contribute to the accelerated atherosclerosis observed in patients with SLE.

Unlabelled: The coronary artery disease is associated with more than threefold-increased risk in diabetes mellitus. Lipoprotein(a) and apo(a), a specific protein of this lipoprotein are risk factors for atherosclerosis. However, the association of apo(a) size with the lipoprotein(a) levels in patients with type 1 diabetes mellitus still controversial., Objective: We investigated the apo(a) polymorphism and its association with lipoprotein(a) levels in children with type 1 diabetes mellitus and their non diabetic first-degree relatives., Methods: This cross-sectional study included 25 type 1 diabetic patients aged 1 to 17 years, one non-diabetic sibling of each patient and both parents. Glucose, lipids, lipoproteins, apoAI, apoB, lipoprotein(a) plasma concentration as well as apo(a) phenotypes were determined., Results: Median plasma lipoprotein(a) concentrations were 8.3, 8.2, 4.2, and 9.3 mg/dL in type 1 diabetes mellitus, siblings, fathers and mothers respectively (p ns). The prevalence of plasma lipoprotein(a) excess (> 30 mg/dL) was not significantly higher in type 1 diabetes mellitus patients than in their non diabetic siblings, or in their parents. Lipoprotein(a) levels and apo(a) distribution were similar in all groups (p ns) and those of parents correlated directly with the lipoprotein(a) and phenotypes of their offspring., Conclusions: Lipoprotein(a) levels and apo(a) size were similar in type 1 diabetes mellitus cases and their first degree relatives and the associations between them were similar too, suggesting that Lp(a) does not appear to explain increased risk of atherosclerosis in patients with this disease.

Unlabelled: Healthy postmenopausal women and hypertensive patients show an imbalance in the modulation of autonomic nervous control of the cardiovascular system, which may increase the cardiovascular risk., Objective: To examine the heart rate variability (HRV) response to estrogen replacement therapy (ERT) and its association with changes in metabolic variables in hypertensive postmenopausal women., Methods: A double-blind, placebo-controlled clinical trial was conducted in 30 hypertensive postmenopausal women receiving 180 mg/day of verapamil. The experimental group (n=16) received 0.625 mg OD of natural conjugated estrogens during 4 months, while control group (n=14) received a placebo. Lipids, lipoproteins, apolipoproteins, glucose and insulin were measured at 0, 2 and 4 months. HRV was determined in time and frequency domains using a 24-h Holter before and after ERT., Results: Significant higher values of spectral and non-spectral parameters of HRV, associated with a lower LF/HF ratio, were found at the end of 4 months of ERT. Multiple regression analysis revealed that estrogen treatment itself and changes in total cholesterol, LDL-cholesterol, glucose and waist circumference, contributed to the changes observed in indexes reflecting parasympathetic activity in time and frequency domains., Conclusions: We conclude that ERT partially improves HRV favoring increased parasympathetic drive, and that part of the effect may be mediated by changes in metabolic variables.

The influence of apolipoprotein E (APOE) genotypes on plasma lipid levels was determined in 278 Mexican individuals. The most frequent genotype was E3/3 (80.5%) followed by E3/4 (12.5%), E2/3 (5.0%), E2/4 (1.4%), and E4/4 (0.3%). Our data are similar to those previously described for Mexican-American and American Indian populations, which show the highest frequency worldwide of the APOE*3 and the E3/3 genotype. Compared to female carriers of the E3/3 genotype, women with the E3/4 genotype presented increased low-density lipoprotein cholesterol (117 +/- 28.0 mg/dL vs. 134.0 +/- 31.7 mg/dL, p < 0.05), and total cholesterol (179.4 +/- 33.4 mg/dL vs. 197.5 +/- 35.4 mg/dL, p < 0.01). Also, we detected increased high-density lipoprotein concentrations in women with the E2/3 genotype (53.7 +/- 19.5 mg/dL) when compared to women with the E3/3 genotype (45.2 +/- 12.0 mg/dL) (p < 0.032). Our data suggest that genetic variation at the APOE locus in the Mexican population is a genetic factor that influences plasma lipid levels. This effect was observed only in the female population. Additional studies attempting to correlate APOE polymorphism with plasma lipid profile in a large number of individuals would be helpful in establishing the true significance of this polymorphism in the Mexican population.

The aim of this study was to investigate the relationship between endothelial dysfunction and low density lipoprotein (LDL) size and susceptibility to oxidation in nephrotic rats with or without deficiency of vitamin E and selenium. Four groups of male Wistar rats were studied: control (C), vitamin E and selenium deficient control (DefC), nephrotic (NS), and vitamin E and selenium deficient NS (DefNS). Nephrotic syndrome was induced by puromycin aminonucleoside. The molar ratio of vitamin E/LDL-cholesterol was significantly lower in DefNS, DefC rats, and NS vs. C rats. In comparison with control animals, vasodilation and LDL oxidability were significantly lower in nephrotic animals. LDL size was similar in all groups. Abnormal endothelial function in response to acetylcholine and carbachol was observed in NS animals compared to control rats. Relaxation response was inversely associated with an increase in LDL susceptibility to oxidation and with a lower molar ratio of vitamin E/LDL-c. LDL oxidability and LDL-c were the only variables independently associated with vasodilation. These results suggest that endothelial dysfunction of NS may be a consequence of the increased LDL susceptibility to oxidation, secondary to antioxidant deficiency.

To determine the association of in vivo concentrations of insulin, obesity, and gender with lipoprotein(a) [Lp(a)] levels, we used a cross-sectional population-based survey of a multistage random sample of the Mexico City adult population. We studied 423 normoglycemic, normotensive subjects from an original sample of 825, comprised of 239 men and 189 women with a mean age of 38.6 years (range, 17 to 90). All subjects were divided into 8 groups according to body mass index, fasting insulin, and gender. Lp(a) concentrations (mg/dL) were similar in obese women with and without high insulin levels (19.9 v 18.6), but hyperinsulinemic obese men had significantly lower Lp(a) levels than normoinsulinemic obese men (7.9 v 29.4). In addition, the proportion of obese men with Lp(a) concentrations of > or = 30 mg/dL was significantly higher in the normoinsulinemic than in the hyperinsulinemic (29.2% v 0.0%). The frequency distribution of Lp(a) levels was shifted to a lower range in hyperinsulinemic men compared with normoinsulinemic men. Our results show that in men, hyperinsulinemic obesity is associated with low Lp(a) levels, while obesity with normoinsulinemia is related to increased Lp(a) concentration. These observations were not found in women. These findings may explain the conflicting results reported by several studies.

Unlabelled: Primary and secondary prevention trials have demonstrated that niacin improves the lipid profile and reduces coronary morbidity and mortality., Objective: To investigate the safety and efficacy of niacin in daily doses of 1.5 and 3.0 g in patients with ischemic heart disease and dyslipidemia., Patients and Methods: Sixty one male and female patients, aged 30 to 70 years were included. Thirty two patients were later excluded; 18 for adverse events and 14 for causes not related to niacin., Results: In the 29 patients that finished the study, niacin in a dose-dependent manner, significantly reduced the levels of total cholesterol, LDL-cholesterol, triglycerides, apoB and LDL-C/HDL-C ratio, and significantly increased HDL-Cholesterol concentrations; a decrease in lipoprotein(a) was observed with both dosages, but the change was significant only with the 3.0 g/day. In 11 patients (38%) lipids and lipoproteins reached ideal concentrations. In 15 patients (52%) C-LDL/C-HDL was lower than or equal to 3.5 at the end of the study., Conclusions: Our results suggest that niacin is well tolerated by 62% of the patients. Niacin is a safe, effective and a low cost alternative in the treatment of patients with ischemic heart disease and dyslipidemia.

Objective: To assess the effect of the new American Diabetes Association (ADA) diagnostic criteria for diabetes in the Mexico City survey., Methods: The data available from the Mexico City study were included. This cross-sectional survey was conducted from January 1991 to March 1992 and involved 805 adults (20 years of age or older; mean age, 41 years). Survey procedures and results were previously published. Of the residents with diabetes, 74.2% had a previous diagnosis, and 25.8% were diagnosed on the basis of fasting plasma glucose (FPG) levels obtained during the survey. For the current report, these data were reanalyzed on the basis of the new ADA diagnostic criteria., Results: The prevalence of newly diagnosed diabetes with use of the old and the new criteria was 23.1% versus 32.3% in men (P = 0.31) and 27.5% versus 36.3% in women (P = 0.32), respectively. The crude prevalence rate of diabetes increased from 8.7% to 9.3% (P = 0.42), and the age-adjusted rate increased from 10.6% to 11.2% for women (P = 0.64) and from 6.0% to 6.5% for men (P = 0.49). The prevalence of impaired FPG was 4.8%. Those patients with impaired FPG or newly diagnosed diabetes with FPG levels between 126 and 140 mg/dL had a more atherogenic risk profile than did those with normal carbohydrate metabolism., Conclusion: On the basis of the 1990 population census in Mexico City, the new ADA criteria will add 28,331 patients with diabetes (6.9%) to an already insufficient medical system. For those patients with impaired FPG or newly diagnosed diabetes on the basis of the new criteria, management should be focused on the control of the diverse and highly prevalent coronary risk factors.

Objective: To establish the prevalence of lipid and lipoprotein (a) abnormalities in patients under hemodialysis or who underwent renal transplantation., Methods: Forty dialyzed patients, 64 transplanted and a comparison group of 77 subjects of the general population paired by gender and age were studied., Results: The most prevalent disorder in the hemodialysis was hypoalfalipoproteinemia followed by Lp(a) excess while the least common disorder was hypercholesterolemia. The transplanted patients had the lowest prevalence of Lp(a) excess and a higher proportion of hypercholesterolemia when compared to hemodialysis patients but similar to that of controls., Conclusion: Our results confirmed some previous findings observations of others but differed in that hypoalfalipoproteinemia and not hypertriglyceridemia was the predominant abnormality in the hemodialysis patients.

Objective: To determine lipoprotein(a) in children and adolescents with IDDM and assess its relation with Lp(a) levels in their first degree relatives., Research Design and Methods: In a cross-sectional study we included 141 IDDM patients, (58 male and 83 female) with mean ages 12.2 +/- 2.8 and 12.6 +/- 3.1 years, respectively. Patients with microalbuminuria, hepatopathy, thyroid dysfunction, infectious disease, acute decompensation or surgery three months prior to the study, were excluded. Clinical history, physical examination, blood chemistry, glycosilated hemoglobin, microalbuminuria and lipid profile including total cholesterol triglycerides, HDL-C, Apo A-I, Apo B and Lp(a) were determined. Parents and non-diabetic siblings were also studied when feasible., Results: Mean plasma concentration of total cholesterol, HDL-C and Apo A-I were significantly higher in diabetic boys compared to their non-diabetic sibs. Mean Lp(a) plasma values and the prevalence of Lp(a) > 30 mg/dL were similar in the IDDM patients, their healthy sibs and parents. Hypercholesterolemia and hypertriglyceridemia were more frequent among the IDDM patients. No correlation was found between HbA1, and Lp(a) concentrations. However, a correlation was observed between Lp(a) plasma concentrations of parents and their diabetic and healthy offspring., Conclusion: Diabetes mellitus does not seem to affect Lp(a) levels. These data are consistent with a genetic regulation of Lp(a) plasma levels.

A cross-epidemiologic study concerning cardiovascular risk factors in a random sample population of Mexico City was carried out in 1991 and 1992. Lipoprotein(a) (Lp(a)) levels in 404 men and 311 women aged 20-90 years were determined by enzyme-linked immunoassay on fasting plasma. Men and women showed similar age-adjusted Lp(a) values. For the whole population the median Lp(a) was 6.9 mg/dL and the prevalence of high Lp(a) (> 30 mg/dL) was 14%. Small positive correlations between Lp(a) and plasma cholesterol (rs = 0.16) and low density lipoprotein cholesterol (LDL-C) (rs = 0.21), and a negative one with insulin (rs = -0.13) were found. In a multiple regression analysis, insulin and LDL-C were the variables that best explained the variation of Lp(a) in our sample. Our data show that Lp(a) in our population is similar to that found in other populations. An association of Lp(a) with myocardial infarction was observed (high Lp(a) was seen in 33% of atherosclerotic individuals versus 14% in healthy subjects) but did not reach statistical significance.

The present report is a description of the characteristics of a studied population and of the methodology used in a study performed to investigate high blood pressure prevalence and cardiovascular risk factors among the adult population of Mexico City. A cross-sectional study was conducted from January 1991 to March 1992. Random samplings of multiple stages was used and 825 adult subjects were studied in Mexico City. The following measurements were registered: blood pressure, body mass index (BMI), waist-hip ratio (WHR), total cholesterol (TC), triglycerides (TG), high density lipoproteins (HDL-C) and low density lipoproteins (LDL-C), lipoprotein (a) (Lp(a)), glucose and insulin. Personal and family history of cardiovascular illness were investigated, as well as exposure to some risk factors such as smoking, alcohol consumption and sedentarism. The response rate was 86.6%. The prevalence of high blood pressure was 21.1%, and of non-insulin dependent diabetes mellitus was 8.7%. Frequency of dyslipidemia in the studied sample was 24.4% for high TG, 23.6% for low HDL-C, 23.6% for high LDL-C, 14.9% for Lp(a) excess (Lp(a) > or = 30 mg/dl; overweight and obesity were more prevalent among women. The diversity of living conditions among the population of Mexico City was included in the sampling strategy design, not only to register the high blood pressure (HBP) frequency in each stratum but to identify other cardiovascular risk factors which could be decisive in the development of HBP. Regarding the features of the studied population, BMI did not reveal differences among men, but their TG levels were higher and HDL levels lower than those of other populations. In women, the results obtained for BMI, WHR, lipids and lipoproteins were also higher compared with the mean reported for other populations.

Objective: To investigate the relationship between fasting insulin concentrations and several metabolic and anthropometric variables in the Mexico City population., Design: Cross-sectional, randomized, stratified by age, sex and economically active and inactive., Subjects: 700 healthy adults, older than 20 years, 396 males and 304 females., Measurements: Body mass index, waist to hip ratio, systolic and diastolic blood pressure, insulin, glucose, triglycerides, total, HDL and LDL cholesterol and lipoprotein(a)., Results: Means for age were 39 +/- 13 years for men and 41 +/- 12 for women (p < 0.05). In males, the mean values of body mass index, waist-to-hip ratio, systolic and diastolic blood pressure, triglycerides, glucose and LDL-cholesterol : HDL-cholesterol increased significantly with higher insulin levels. A significant inverse tendency was observed for the mean concentrations of HDL-cholesterol and lipoprotein(a). Age, total cholesterol and LDL-cholesterol were not related to the insulin levels. A similar pattern was observed in women, significance, however, was only obtained for the body mass index, triglycerides, glucose, HDL-cholesterol and lipoprotein(a). Age-adjusted multiple regression analysis showed that insulin was directly and independently associated to triglyceride levels and inversely with lipoprotein(a) concentrations for both sexes, and with HDL-C, only in males., Conclusions: The prevalence of insulin resistance related metabolic disorders was high in a random sample of the Mexico City population. Increased cardiovascular risk factors associated with the insulin resistance syndrome were observed with higher insulin levels, and lipoprotein(a) was inversely and significantly related to insulin. Preventive strategies are urgently needed to avoid the already increased incidence of morbidity and mortality associated to atherosclerotic disease.

Objective: To investigate the prevalence of microalbuminuria in children and teenagers with IDDM and its relationship with other variables., Methods: We studied 160 IDDM children and teenagers with a mean age of 13 +/- 4 years from our endocrine department outpatient clinic. A complete medical history was obtained as well as a fasting blood sample for glycemia, glycosilated hemoglobin and lipid profile and a urine sample for microalbuminuria using laser immunonephelometry., Results: 13 patients (8%) had microalbuminuria (20-200 micrograms/min) and 5 (3%) clinical proteinuria (> 200 micrograms/min). The abnormal excretion was more prevalent in females with the poorest metabolic control, the longest duration of diabetes, and the highest age (13-18 years). The presence of microalbuminuria or clinical proteinuria associated with a more atherogenic risk profile compared to patients with a normal urinary albumin excretion., Conclusions: There was a poor metabolic control in our IDDM population. In addition, our current findings in a population with a relatively short duration of their diabetes point out the need to improve an integral management strategy to prevent or delay the late complications associated with IDDM.

The purpose of this study was to investigate the effects of long-term high level physical exertion on plasma lipids and lipoproteins. Ninety-one young athletes, 70 men and 21 women, who practiced sports such as running, swimming, rowing, boxing and soccer, were studied. The control group included 101 healthy subjects, 77 men and 24 women, with sedentary life style. The mean plasma levels of total cholesterol (TC) (p = 0.04), low-density lipoprotein cholesterol (LDL-C) (p = 0.04) and the atherogenic index (p = 0.01) were lower, and high-density lipoprotein cholesterol (HDL-C) (p < 0.005) significantly higher in male athletes than in controls. Mean plasma lipids and lipoproteins concentrations were not significantly different in sportswomen when compared with their controls. The prevalence of hypercholesterolemia, hypertriglyceridemia and low HDL-C levels, were lower in male and female athletes of the five sport disciplines than in sedentary controls; however, only hypercholesterolemia (p < 0.05) and the atherogenic index (p < 0.01) were statistically different. These results, consistent with data previously published, show that low plasma levels of TG and high levels of HDL-C characterizes the athletes who practice an aerobic physical activity; additionally, in male athletes we found that long-term exercise appears to reduce LDL-C plasma levels. This latter finding agree with most, but not all, studies in the literature. We conclude that athletes have a lipid profile that may be protective against the development of atherosclerosis.

Familial hypercholesterolemia (FH) is the genetic lipid disorder with a higher risk to develop coronary heart disease (CHD). In the heterozygous patients there are, however, variability in the atherosclerosis age of onset and severity. In recent years, it has been reported elevated levels of Lp(a) in FH, and it is proposed that this lipoprotein contributes to the development of CHD in these patients. This study evaluates the relationship between Lp(a) levels and the presence of CHD in FH. We included 38 patients with heterozygous FH with or without CHD (13 and 25 respectively), and a control group. In comparison to the control group, FH patients had significant elevated levels of Lp(a) (median 8.1 vs 16 mg/dL), and a greater prevalence of hyper Lp(a) (with a cut-off level of 30 mg/dL) (11.4 vs 25.7%). FH patients with CHD had higher levels of Lp(a) than those without CHD (22.8 vs 14.4 mg/dL). A significative negative correlation between age of onset of CHD and Lp(a) levels was found in females. CHD in FH was associated with male gender, older age, higher prevalence of hypertension, higher waist/hip ratios, higher levels of triglycerides and prevalence of hypertriglyceridemia. Our findings suggest that Lp(a) may play a role as an additional risk factor to develop atherosclerosis in FH.

In Mexico, the incidence and prevalence of coronary heart disease has increased over the past three decades and has become the leading cause of death in some areas of the country. Hypercholesterolemia (HC) is a major risk factor for coronary atherosclerosis and most developed countries currently have public health strategies that attempt to reduce the level of cholesterol. In order to learn the mean total cholesterol values and the prevalence of HC, an epidemiologic survey was carried out in a representative population sample that included men and women aged 1 to 98 years, across the nation. In this report, we present the findings in children and teenagers of both sexes (n = 34369). Considering the country as a whole, the mean serum TC was 147 +/- 35 mg/dl, the prevalence of borderline hypercholesterolemia (TC between 170 and 199 mg/dl) was 14.7% and the prevalence of high risk hypercholesterolemia (TC > or = 200 mg/dl) was 6.7%. This cross sectional study demonstrated the existence of significant geographic differences in serum TC, with mean state values ranging from 133 mg/dl in the south to 164 mg/dl in the north. The prevalences of high risk hypercholesterolemia was as high as 18.2% in Baja California Norte and as low as 2.5% in the state of Morelos. These geographic differences in total cholesterol and prevalence of hypercholesterolemia were already present at one year of age and persisted throughout childhood and adolescence.

Cholesterol, triglycerides and lipoprotein levels were assayed in serum of 152 children and teenagers with IDDM and in 228 non-diabetic siblings. A poor control of diabetes, reflected by high levels of glycosylated hemoglobin and/or high fasting blood glucose, was associated with statistically significant increases in total cholesterol, LDL-cholesterol and triglycerides, and a reduction in HDL-cholesterol. Mean total cholesterol levels in diabetic patients (171 +/- 33 mg/dL for males and 199 +/- 53 mg/dL for females) were statistically higher than those in their siblings (158 +/- 30 mg/dL and 164 +/- 33 mg/dL respectively). The prevalence of hypercholesterolemia (HC) and hypertriglyceridemia (HTG) were higher in the diabetic patients but statistically significant exclusively in females (prevalences of 40% vs 12% for HC and 30% vs 9% for HTG with a p value < 0.005). The diabetic patients in good metabolic control had similar lipid levels to those of their non-diabetic siblings. These data support the hypothesis that poor control of blood glucose is associated with atherogenic lipid profiles. The prevalence of hypercholesterolemia is impressively high in our diabetic population and indicates that all IDDM patients should have a serum lipid and lipoprotein analysis done annually; blood glucose control and dietary guidelines should be improved in these cases.

The postprandial (PP) elevations in triglyceride rich lipoproteins (TRL) are potentially atherogenic. We compared PP lipemia in non insulin dependent diabetes mellitus (NIDDM) with hypoalphalipoproteinemia (HA) and patients with primary HA. Eight males in each group, mean age +/- SD 54 +/- 10 years, were studied for 12 hours after the ingestion of a fat load (65 g of fat/square meter of body surface). Plasma glucose, triglycerides (TG) and cholesterol (C) in plasma and in the different lipoprotein fractions were measured. The PP triglyceridemia was significantly greater in NIDDM patients with HA and correlated with the fasting TG concentrations. The curve pattern of the lipemia (% delta) was otherwise similar in the patients with secondary or primary HA; only the triglyceridemia persisted for a longer period of time in the latter but was otherwise similar to that of the NIDDM patients with lower basal triglyceride values. Patients with primary HA may have a disturbed metabolism of triglyceride rich lipoproteins which have a delayed depuration during the postprandium. Basal HDL-C in patients with HA cannot predict the PP triglyceridemia.

The postprandial (PP) elevations in triglyceride rich lipoproteins are potentially atherogenic. To describe the characteristics of PP lipemia after a fat load in non insulin dependent diabetes mellitus (NIDDM) and evaluate the response to a fibric acid derivative, seven males with NIDDM were studied for 12 hours after the ingestion of a fat load (65 g of fat/square meter of body surface). Plasma glucose, and triglycerides and cholesterol levels were measured in total plasma and in the different lipoprotein fractions. The fat load study was repeated after four weeks of treatment with gemfibrozil (GEM) 600 mg x 2. PP triglyceridemia correlated significantly with the fasting triglyceride concentrations. Basal triglyceride levels diminished significantly with the use of gemfibrozil and so did the magnitude of the PP triglyceridemia. Otherwise the curve patterns of lipemia were similar before and after the use of the fibrate; only the triglyceridemia persisted for a longer period of time. Patients with NIDDM may have a significant PP lipemia which is not likely related to the diabetes per se as to the increased triglyceride levels frequently observed in these patients.

The tolerance and efficacy of cholestyramine (12-16 gr/day) was evaluated in 19 patients with primary type-IIa hyperlipoproteinemia. All patients were on an isocaloric low-cholesterol diet that began at least one month before entry, and was continued during the eight weeks of the study. Cholestyramine significantly (p less than 0.001) lowered the plasma levels of cholesterol and of low density lipoprotein cholesterol from means of 288 +/- 46 mg/dl to 244 +/- 44 mg/dl and from 221 +/- 50 mg/dl to 171 +/- 46 mg/dl respectively. These were reductions of 15 and 22%. The magnitude of response to cholestyramine was unrelated to age, sex, cause of the hypercholesterolemia (familial or polygenic) or basal cholesterol levels. The drug was well tolerated. Only one patient was excluded because gastrointestinal discomfort. Because of its safety and efficacy, cholestyramine can be recommended as a first choice drug in the treatment of hypercholesterolemia.

Atherosclerosis is more common and severe in DM. The purpose of this study was to compare the blood lipids profile and the prevalence of different coronary risk factors (CRF) in a mexican population with CHD (coronary heart disease) and DM compared with non DM patients. All had a history of myocardial infarction. Patients with nephropathy or other secondary causes of dyslipidema were excluded. There were two groups of 45 patients, 32 males, 13 females; age was 60 +/- 1 (SEM), body mass index (BMI) 26 +/- 6. Diabetes duration was 10 +/- 1 years. Diabetic individuals referred smoking in 58%, high blood pressure 55%, obesity (IQ greater than 27) 42%. There were no statistical differences with the non DM group. The mean values of total cholesterol, LDL cholesterol and triglycerides were similar in diabetics and non diabetics. HDL cholesterol was significantly lower in diabetic females (p less than 0.01). Hypoalphalipoproteinemia (HDL-C less than or equal to 30 mg/dL) was the most common abnormality in both groups (52% DM vs 38% nonDM) (p less than 0.01) Type IV phenotype was present in 40 vs 29% (NS). Lipid values were not related to BMI, metabolic control or diabetes type of treatment. To conclude, non insulin dependent diabetic patients with CHD have a high prevalence of CRF. Lipid abnormalities, particularly hypoalphalipoproteinemia and hypertriglyceridemia, could be a cause for the increased atherogenic risk, particularly in females.

The results of lipoprotein studies performed in 67 members of 10 kindreds with familial hypoalphalipoproteinemia are presented. Probands were ten patients referred to the Lipid Clinic of the National Institute of Cardiology for evaluation of their lipid profile, all of whom had history of a definite myocardial infarction occurring before they had reached age 60. Their only plasma lipid abnormality was a reduction of the cholesterol fraction associated with high-density lipoproteins (C-HDL) below the corresponding age-sex specific fifth percentile. We studied 57 other individuals including probands spouses and available first-degree relatives. All participants were clinically examined and their complete coronary risk factor profile was assessed. After a 12 hour fast, plasma samples were obtained for lipid analysis, total cholesterol and trïglycerides were measured by enzymatic methods, C-HDL was determined in the supernatant after plasma precipitation with magnesium chloride: phosphotungstic acid. Low-density lipoprotein cholesterol (C-LDL) was estimated with the formula proposed by DeLong. For every family a pedigree was constructed and statistically analyzed to assess the within-family clustering of low C-HDL levels and the pattern of transmission of the abnormal phenotypes. Mean C-HDL level for propositii was 24.3 mg/dl, the corresponding value for the C-LDL/C-HDL ratio (atherogenic index) was 4.9 and it was elevated above 3.5 (average coronary risk) in 7/10 (70%) of these patients. Obesity, defined by a Quetelet index above 28 in men and 26 in women was present in 4/10 (40%) of the probands, 3/10 (30%) had stable non insulin-dependent diabetes mellitus, prevalence figures for the other coronary risk factors was very low. In addition to probands, the hypoalphalipoproteinemic phenotype was found in 30/57 (52.6%) subjects including spouses (two cases) and first-degree relatives. For these 30 cases the mean C-HDL value was 32 mg/dl. In all ten reported kindred, we clearly observed either horizontal, vertical or both types of within-family transmission of the aberrant phenotype. This finding was considered to be most compatible with the presence of a primary genetic abnormality affecting C-HDL metabolism in all these kindreds in spite of the fact that some of the probands had some conditions like diabetes or obesity that are sometimes associated with secondary reductions of C-HDL. Due to the lack of a reliable biochemical marker, the distinction between primary and secondary hypoalphalipoproteinemia in individual cases is frequently impossible, for this reason the diagnostic assessment depends on family studies.(ABSTRACT TRUNCATED AT 400 WORDS)