Divergent levels of high density lipoprotein cholesterol and apolipoprotein A-I in children. The Bogalusa Heart Study

High-density lipoprotein cholesterol to apolipoprotein A1 ratio and all-cause mortality among incident peritoneal dialysis patients

BACKGROUND AND AIMS

The ratio of high-density lipoprotein cholesterol to apolipoprotein A1 (HAR) is associated with all-cause mortality in nonchronic kidney disease patients, but its role in predicting all-cause mortality in patients undergoing peritoneal dialysis (PD) is still unclear. The purpose of this study was to investigate the relationship between HAR and all-cause mortality in patients with PD.

METHODS AND RESULTS

The medical records of 1199 patients with PD from November 1, 2005, to August 31, 2019, were collected retrospectively. The main outcome was defined as all-cause mortality. The HAR was divided into three groups by X-tile software. The association between HAR and all-cause mortality was evaluated by Cox models. The Kaplan-Meier method was used for the survival curve. The median follow-up period was 35 months (interquartile range: 20-57 months), with a total of 326 deaths recorded. After multiple adjustments, the risk of all-cause mortality in the high HAR group was 1.96-fold higher than that in the low HAR group (hazard ratio: 1.96; 95% CI, 1.22 to 3.15; P = 0.005). The restricted cubic splines showed that the risk of all-cause mortality increased gradually when HAR was >0.37. In the stratified analysis, a high HAR was linked to a high risk of all-cause mortality in males, patients under 55 years old, and patients without diabetes or cardiovascular disease (CVD).

CONCLUSION

This study suggests that HAR is independently related to all-cause mortality in PD patients, especially in males, patients under 55 years old, and patients without diabetes or CVD.

Apolipoprotein E4 phenotype increases non-fasting serum triglyceride concentration in infants - the STRIP study

As genetically determined apolipoprotein E (apo E) phenotypes influence serum cholesterol concentration, we analysed whether serum triglyceride values are also affected by the apo E phenotypes in infants. Non-fasting serum triglyceride values were measured in 7- and 13-month-old participants in the STRIP project, a randomised, prospective trial aimed at reducing children's exposure to known atherosclerosis risk factors (n=1062). The mean+/-S.D. non-fasting serum triglyceride concentrations in 7-month-old infants with apo E4/4 (n=36), E3/4 (n=209), E3/3 (n=412), and E2/3 (n=66) were 2. 05+/-1.24, 1.81+/-0.90, 1.63+/-0.90, and 1.71+/-0.83 mmol/l, respectively. Triglyceride concentrations were higher in infants with apo E4/4 or 3/4 than in those with apo E3/3 (P-value for difference 0.01 and 0.009, respectively). The apo E phenotype similarly influenced non-fasting serum triglyceride concentrations at the age of 13 months. The differences in serum triglyceride values in apo E4(+) infants (apo E3/4 and 4/4 infants combined) and apo E4(-) infants (apo E2/3 and 3/3 infants combined) occurred independently of the relative weight of the infant, milk type used at 7 months of age (breast milk or formula), and time elapsed from the previous meal. To conclude, apo E phenotypes regulate non-fasting serum triglyceride values in healthy infants. Apo E3/4 and apo E4/4 predispose infants to higher values than apo E3/3 phenotype, suggesting that the varepsilon4 allele may increase atherosclerosis risk also via it's effect on postprandial triglyceride metabolism.

Childhood lipoprotein profiles and implications for adult coronary artery disease: the Bogalusa Heart Study

Serum lipoproteins are important risk factor variables for coronary artery disease (CAD). Studies of a large population of young individuals show changes in lipoproteins in childhood are race- (black-white) and sex-specific and certain changes occur during growth phases. White boys show adverse changes in lipoprotein levels during sexual maturation that mark them at high risk for CAD. Further, low-density lipoprotein particles are relatively apolipoprotein B enriched in white children, especially boys, a characteristic associated with low levels of high-density lipoprotein cholesterol. The impact of apolipoprotein E genotype on serum lipoproteins seen in adults is already apparent in children, which may be helpful in identifying a high-risk group. Observations of child-parent associations in terms of parental myocardial infarction and levels of lipoprotein variables in the offspring suggest that childhood profiles of lipoprotein (a), apolipoprotein A-I, and apolipoprotein B may be helpful as markers of future CAD. Clustering of increased levels of truncal fat, insulin, and blood pressure is often seen in young adults with an adverse lipoprotein profile. This clustering is related to subtle abnormalities in carbohydrate and lipid metabolism and obesity in childhood. The fact that lipoprotein levels persist from childhood to young adulthood underscores the importance of detection and management of dyslipidemia early in life.

Serum lipid values in adolescents are related to family history, infant feeding, and physical growth

Total serum cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglycerides (TG), apolipoprotein A-I (apo A-I), apolipoprotein B (apo B), and lipoprotein (a) (Lp(a)) were analysed in 879 14- and 17-year-old healthy adolescents (477 boys and 402 girls), and related to family history of cardiovascular disease, early feeding, weight and length at birth, and physical growth during infancy and childhood. Mean TC was significantly higher in girls than in boys (4.4 and 4.2 mmol/l, respectively, both age-groups together). High TC values ( > 5.2 mmol/l) were more prevalent in girls than in boys: 14% and 17% compared to 6% and 12% in 14- and 17-year-old girls and boys, respectively. Mean TC and LDL-C values were lower during mid-puberty in both boys and girls while, in boys but not in girls, mean HDL-C values decreased and TG values increased successively with increasing pubertal stage. Girls who were taking oral contraceptives had higher mean values of TC (4.91/4.39 mmol/l), TG (1.32/0.83 mmol/l), and apo B (0.89/0.73 g/l). Boys with a family history of early deaths ( < 55 years) from myocardial infarction and girls with a family history of cerebral haemorrhage/thrombosis in fathers had higher mean values of TC (4.55/4.17 and 5.03/4.40 mmol/l, for boys and girls, respectively), LDL-C (2.84/2.47 and 3.08/2.56 mmol/l), and apo B (0.73/0.70 and 0.86/0.73 g/l). Adolescents with short duration of breast feeding ( < 6 months), or early introduction of infant formula, had higher mean values of TC (4.29/4.14 mmol/l) and apo B (0.72/0.68 g/l). There were no significant correlations between serum lipid values and body weight or length at birth, but adolescents with high LDL-C (upper quartile) seemed to have lower attained heights during infancy and childhood. In conclusion, this study shows that serum lipids in adolescence are primarily related to age and sex but also to early determinants like family history of cardiovascular diseases, infant feeding, and early physical growth.

Epidemiologic studies of menopause: changes in risk factors and disease

There have been important studies of changes in risk factors and psychosocial variables during peri- and postmenopause. Most of the studies have been done in whites. Studies have clearly documented changes in behavior and biological variables related to menopause. The most critical questions bear on the interrelationships between sex steroid hormone levels, life-styles, including diet, exercise, alcohol consumption, obesity, and changes in key risk factors that are associated with the major causes of morbidity and mortality among postmenopausal women. The best study designs should be longitudinal and include frequent, accurate, and reproducible measurements of biological and psychosocial variables. Importantly, studies should be done in heterogeneous populations. The most critical variables may be measures of the degree of obesity and fatness, diet, and exercise and their relationship to hormonal changes occurring during the peri- and postmenopausal period.

Relation of serum lipoprotein lipids and apolipoproteins to obesity in children: the Bogalusa Heart Study

BACKGROUND

The relationship of serum lipoprotein lipids and apolipoproteins to obesity was studied in a biracial sample of 2,816 children of ages 5-17 in Bogalusa, Louisiana.

METHODS

Two measures of obesity were used: fatness (subscapular skinfold thickness) and fat centrality (the ratio of subscapular to triceps skinfold thickness). Plasma insulin and glucose were included as metabolic markers related to obesity.

RESULTS

The obesity associations were relatively strong with insulin (rs = 0.29, P less than 0.001, skinfold; rs = 0.15, P less than 0.001, skinfold ratio) and triglycerides (rs = 0.25, P less than 0.001, skinfold; rs = 0.19, P less than 0.001, skinfold ratio). The relationships of serum low-density lipoprotein cholesterol (LDL-C) (rs = 0.17, P less than 0.001, skinfold; rs = 0.13, P less than 0.001, skinfold ratio) and apolipoprotein (apo) B (rs = 0.16, P less than 0.001, skinfold; rs = 0.13, P less than 0.001, skinfold ratio) with the obesity measures were of lesser magnitude, but persisted after adjustment for insulin and triglycerides. The inverse association of obesity to serum high-density lipoprotein cholesterol (HDL-C) (rs = -0.13, P less than 0.001, both skinfold and skinfold ratio) and apo A-I (rs = -0.04, P = 0.03, skinfold; rs = -0.05, P = 0.004, skinfold ratio) was significant only before adjustment for insulin and serum triglycerides. Multiple linear regression of obesity measures showed that, like insulin, serum triglycerides had consistently higher standardized coefficients than LDL-C, HDL-C, apo B, and apo A-I. Apo A-I and apo B added only a small amount (less than 2%) of information to the relationship of serum lipoproteins with obesity measures.

CONCLUSION

These results indicate that serum very-low-density lipoprotein (VLDL) levels are directly and independently related to obesity. The well-known inverse association between obesity and serum HDL-C is not independent, but secondary to the elevated VLDL or triglyceride levels associated with obesity. While associations of obesity and lipoprotein cholesterol are found, far fewer occur with apolipoproteins, especially Apo A-I. Interesting race and sex differences in the relationship of obesity to serum lipoproteins and apoproteins are noted, being greater among white children and more consistent in white males.

Plasma concentrations of apolipoprotein A-I containing particles in normolipidaemic young men

Low levels of plasma high-density lipoprotein (HDL)-cholesterol and apolipoprotein (apo)-A-I are associated with premature coronary heart disease. However, particles in the density range of HDL are heterogeneous. Two main types of apo A-I-containing particles can be identified, one species containing both apo A-I and apo A-II (Lp A-I:A-II) and the other apo A-I but no apo-A-II (Lp A-I). This study was designed to measure HDL cholesterol, apo A-I, and, using a new procedure, Lp A-I in 233 healthy normolipidaemic young men (cholesterol less than 250 mg dl-1 and triglycerides less than 200 mg dl-1). Among these subjects, the composition of HDL was very variable as indicated by the 10th and the 90th percentiles of the HDL-cholesterol/apo A-I ratios which were 0.32 and 0.49, respectively. The 10th and 90th percentiles of apo A-I and Lp A-I:A-II were 126 and 167 mg dl-1 and 83 and 116 mg dl-1, respectively. On the other hand, Lp A-I showed a much larger variation, the 10th and 90th percentiles being at 33 and 62 mg dl-1, respectively. The distribution of individual values of Lp A-I showed that this fraction of apo A-I-containing particles was very variable among subjects, the Lp A-I/apo A-I ratio extending from 0.18 to 0.58. Triglycerides, Lp A-I and Lp A-I:A-II were correlated with HDL cholesterol, but no correlation between apo A-I containing subfractions and plasma triglycerides was noticed. Since preliminary results from angiographic and clinical studies show that Lp A-I could exert a protective role for atherosclerosis, it would seem that the measurement of Lp A-I might help in the future to characterize better the individual's risk for atherosclerosis.

The effects of generation and gender on the joint distributions of lipid and apolipoprotein phenotypes in the population at large

The generation and gender effects on the joint distributions of total plasma cholesterol (Total-C), ln triglycerides (lnTrig), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), apolipoproteins AI (Apo AI), AII (Apo AII), and E (lnApo E) were studied in 184 male grandparents (MGP), 242 female grandparents (FGP), 237 male parents (MP), 235 female parents (FP), 202 male children (MC), and 200 female children (FC). Homogeneity of variance tests revealed that lipid variances were gender and/or generation specific while apolipoprotein variances were homogeneous across strata. In the absence of heterogeneity of variance, significant heterogeneity in LDL:lnTrig and lnTrig:Apo AII covariation was found between genders in the parental generation. In the presence of heterogeneity of variance, significant heterogeneity of correlation between genders and/or across generations was found for the HDL-C:LDL-C, Total-C:LDL-C, Total-C:lnTrig, lnTrig:LDL-C, Total-C:lnApo E and HDL-C:lnApo E bivariate distributions. Analyses of principal components revealed that the generation and gender specific cohorts have similar eigenvalues but distinct eigenvectors for the first two principal components underlying the seven dimensional lipid and apolipoprotein distribution. We conclude that the amount of variability explained by the first two principal components is the same across cohorts but how the interindividual variability is distributed among the lipid and apolipoprotein traits is generation and gender specific. This study documents the role that variance and covariance might play in determining risk of disease for special subgroups of the population at large. It also demonstrates how variances and covariances between risk factors traits characterize life processes of aging and sexual dimorphism. This study argues that future biometrical genetic and epidemiological studies of coronary artery disease must take into account age and gender effects on interindividual variability and covariability of risk factors.

Apolipoprotein measurements in clinical biochemistry and their utility vis-a-vis conventional assays

Qualitative and quantitative measurements of apolipoproteins such as Apo CII and Apo E, as well as Apo AI and Apo B can aid in the diagnosis of specific lipoprotein metabolic defects. When used in this way, their usefulness will probably remain more or less confined to specialized research centers which have the expertise to perform such analyses and interpret the measurements. In addition, however, Apo AI and Apo B also promise to be useful for the estimation of cardiovascular risk both in individuals and in populations, and both of these apolipoprotein measurements will probably supplement rather than replace conventional lipoprotein measurements. As with the lipoproteins, the usefulness of Apo AI and Apo B measurements will depend on the accuracy and precision with which they can be measured. The current standardization efforts should lead to the development of reference methods for the measurement of total plasma levels of Apo AI and Apo B, the availability of reference materials for these apolipoproteins, and eventually, to the establishment of methods that can specifically measure Apo AI and Apo B in particular lipoprotein subfractions.