Fasting plasma insulin modulates lipid levels and particle sizes in 2- to 3-year-old children

Estimation of LDL Particle Size Using Lipid Indices: A Population-Based Study of 1578 Schoolchildren

BACKGROUND

Low-density lipoprotein (LDL) is atherogenic and LDL particles are reduced in diameter in the presence of insulin resistance, forming small, dense LDL. This study was conducted to assess the relationship between commonly used lipid indices and LDL particle size and furthermore to clarify the best surrogate lipid markers that could conveniently be used to estimate LDL particle size in children.

METHODS

We determined LDL particle diameter by gradient gel electrophoresis in 1578 children aged 10-12 years. At the fasting state, the relationships between measured LDL particle size and lipid variables [total cholesterol (TC), triglycerides (TG), LDL-cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), atherogenic index [(TC-HDL-C)/HDL-C, TG/HDL-C, LDL-C/HDL-C, and LDL-C/apolipoprotein B (Apo B) and non-HDL-C (TC-HDL-C)] were analyzed.

RESULTS

The LDL particle diameter was 26.64 (mean) ± 0.48 (SD) nm in boys (n = 820) and 26.66 ± 0.49 nm in girls (n = 758); there was not a statistically significant difference. There were statistically significant correlations between LDL particle size and TG or HDL-C concentrations (r = 0.28∼0.37), but the correlations with LDL-C and ApoB were very weak. The combined lipid measures, such as atherogenic index, TC/HDL-C, TG/HDL-C, and LDL-C/HDL-C showed moderate correlations (r = 0.33∼0.38) with LDL particle size; however, the correlation of non-HDL-C with LDL particle size was weak (r = 0.18∼0.19). Simple HDL-C measure appeared to be of comparable value to combined lipid measures.

CONCLUSIONS

Our data indicate that various lipid indices are not superior to HDL-C levels alone as a clinical tool for estimating LDL particle size. Non-HDL-C was less valuable in this aspect.

Lipoprotein particle concentrations in children and adults following Kawasaki disease

OBJECTIVE

To test the hypothesis that children and adults with a history of Kawasaki disease (KD) are more likely to have abnormal lipoprotein particle profiles that could place them at increased risk for developing atherosclerosis later in life.

STUDY DESIGN

Fasting serum samples were obtained from 192 children and 63 adults with history of KD and 90 age-similar healthy controls. Lipoprotein particle concentrations and sizes were measured by nuclear magnetic resonance spectroscopy (LipoScience Inc, Raleigh, North Carolina), and serum was assayed for total cholesterol (TC), triglycerides, and high-density lipoprotein (HDL) cholesterol (HDL-C). Low-density lipoprotein (LDL) cholesterol was estimated using the Friedewald formula. Data were analyzed in a least-square means model, with adjustment for age and sex and with the use of Holm correction for multiple comparisons.

RESULTS

Compared with respective control groups, both adult and pediatric subjects with KD had significantly lower mean very low-density lipoprotein-chylomicron particles, intermediate-density lipoproteins, triglycerides, and TC concentrations. Pediatric subjects with KD had significantly lower LDL particle and LDL cholesterol concentrations and lower mean TC/HDL-C ratio (P < .001). In contrast, the adult subjects with KD had significantly lower HDL particle, small HDL particle, and HDL-C concentrations (P < .001), but HDL-C was within normal range.

CONCLUSIONS

Nuclear magnetic resonance lipoprotein particle analysis suggests that pediatric and adult subjects with KD, regardless of their aneurysm status, are no more likely than age-similar, healthy controls to have lipid patterns associated with increased risk of atherosclerosis.

The role of metabolic syndrome components and adipokines in insulin resistance in prepubertal children

OBJECTIVE

Insulin resistance has a central role in the pathophysiology of cardiovascular atherosclerotic disease. Adipose tissue is of capital importance in view of its production of adipokines. The present study aims to determine the association of metabolic syndrome components, which constitute risk factors for cardiovascular atherosclerotic disease, and leptin and adiponectin with insulin resistance in prepubertal children.

METHODS

We conducted a cross-sectional study involving 197 children. Of these, 112 children were obese, 36 were overweight and 49 had normal weight. The association of sex, waist circumference, Acanthosis nigricans, age, BMI Z-score, serum lipids, leptin and adipocytokines with insulin resistance [defined as the homeostatic model assessment for insulin resistance (HOMA-IR) index higher than or equal to 2.5] was investigated using logistic regression.

RESULTS

There was positive association of sex (female), age, BMI Z-score, triglycerides and leptin with insulin resistance (p<0.05).

CONCLUSION

Among the conventional components of metabolic syndrome, the role of BMI Z-score and triglycerides stands out in insulin resistance of prepubertal children. Sex (female), age and leptin also showed to be of major importance.

The effect of insulin resistance and obesity on low-density lipoprotein particle size in children

OBJECTIVE

In adults, it was shown that obesity and insulin resistance affect low-density lipoprotein (LDL) particle size and small dense (sd) LDL is associated with cardiovascular diseases. In this study, we investigated the effect of obesity and insulin resistance on LDL particle size.

METHODS

Twenty-six obese children (13 girls, 13 boys) with a median age of 10.5 years and 27 healthy control subjects (17 girls, 10 boys) with a median age of 11.5 were enrolled in the study.

RESULTS

The number of patients with insulin resistance in the obese group was 15 out of 26. In the control group, there was no subject with insulin resistance. Serum triglyceride and very LDL (VLDL) levels were higher and serum high-density lipoprotein levels (HDL) were lower in the obese patients than in the controls. There was no statistical difference in the LDL particle size between the two groups (medians: 26.6 vs. 26.7 nm (p=0.575)). The size of LDL particle was not correlated with body mass index (BMI) standard deviation score (SDS), homeostasis model assessment of insulin resistance (HOMA-IR), or serum lipids.

CONCLUSION

Measurement of LDL particle size as a routine procedure is not necessary in childhood obesity.

Adiposity is associated with endothelial activation in healthy 2-3 year-old children

Adiposity is associated with C-reactive protein level in healthy 2-3 year-old children and with other markers of endothelial activation in adults, but data are lacking in very young children. Data from 491 healthy Hispanic children were analyzed. Mean age was 2.7 years (SD 0.5, range 2-3 years); mean body mass index (BMI) was 17.2 kg/m2 (SD 1.9) among boys and 17.1 kg/m2 (SD 2.1) among girls. E-selectin level was associated with BMI (R = 0.11; p < 0.02), ponderal index (p < 0.02), waist circumference (p = 0.02), fasting insulin (p < 0.02), and insulin resistance (p < or = 0.05); these associations remained significant after adjustment for age, sex and fasting glucose. sVCAM was also associated with BMI (R = 0.12; p < 0.05). These observations indicate that adiposity is associated with inflammation and endothelial activation in very early childhood.

Increasing physical activity in preschool: a pilot study to evaluate animal trackers

OBJECTIVE

This report describes a pilot study to evaluate Animal Trackers (AT), a preschool program designed to (1) increase structured physical activity (PA) during the preschool day; (2) increase practice of gross motor skills; (3) provide teachers with an easy-to-use PA program regardless of teacher experience; and (4) implement a teacher walking intervention.

DESIGN

Pilot observational study in volunteer preschools.

SETTING

Nine preschools in New Mexico.

PARTICIPANTS

Two-hundred seventy 3- to 5-year-old children and 32 teachers.

INTERVENTION

Daily 10-minute classroom activities for children.

MAIN OUTCOME MEASURE

Implementation and duration of AT activities, teacher preparation time, and added weekly time spent in structured PA.

ANALYSIS

Process evaluation to track program implementation, and pre-post measures to assess outcomes.

RESULTS

AT activities were implemented 4.1 times per week (11.4 minutes/activity), with 7 minutes teacher preparation time. Overall, AT added 47 minutes of structured PA per week for children.

CONCLUSIONS AND IMPLICATIONS

The AT program increased structured PA time in preschools. Teachers felt that AT was developmentally appropriate; that children enjoyed the activities; and that the children's motor skills improved. Results of the pilot study are encouraging, since research suggests that even small increases in PA could help prevent obesity.

Age, sex, and ethnic variations in serum insulin concentrations among U.S. youth: findings from the National Health and Nutrition Examination Survey 1999-2002

OBJECTIVE

Distributions of serum concentrations of insulin among adolescents and young adults are poorly understood in the U.S. The objective of this study was to describe the distribution of serum insulin across demographic characteristics of U.S. adolescents and young adults.

RESEARCH DESIGN AND METHODS

A total of 1,791 male and female subjects aged 12-19 years who participated in the National Health and Nutrition Examination Surveys for 1999-2002 were included in the analyses.

RESULTS

Among male participants, serum concentrations of insulin increased from age 12 to 14 years before decreasing. Among female participants, concentrations were highest at age 13 years before decreasing steadily through age 19 years. Among participants aged 12-17 years but not those aged 18-19 years, females had higher mean log-transformed concentrations than males (P, Wald, F = 0.038 and 0.125, respectively) after adjusting for age and ethnicity. After adjusting for age and BMI percentile, mean log-transformed concentrations were higher in African-American females aged 12-17 years than in white or Mexican-American participants. No significant ethnic differences were found among female participants aged 18-19 years or male participants aged 12-19 years. Concentrations of insulin increased strongly with increasing levels of BMI.

CONCLUSIONS

These results provide detailed information about serum concentrations of insulin in a representative sample of U.S. adolescents and young adults and may be useful to monitor future trends of this risk factor for diabetes and cardiovascular disease.

Low-density lipoprotein (LDL) particle size in healthy prepubertal children: the STRIP study

BACKGROUND

Small, dense low-density lipoprotein (LDL) particles (diameter < 255 Angstrom) are highly atherogenic, and in adults they are associated with an elevated risk of coronary heart disease (CHD).

AIM

To examine possible contributors to LDL particle size distribution in healthy prepubertal children.

METHODS

We determined LDL particle size in 176 7-y-old children by non-denaturing polyacrylamide gel electrophoresis. Children were divided into two groups in two ways: by using the median of their average LDL particle diameter (261.2 Angstrom) or by using the LDL peak particle diameter (255 Angstrom) as the cut-off point.

RESULTS

Children with smaller LDL particles did not significantly differ from children with larger LDL particles with respect to anthropometric variables, serum triglyceride concentration (in all children < 1.7 mmol/L), apoE phenotype, amount and quality of dietary fat, or child's family history of CHD. Furthermore, LDL particle size did not correlate with any of the anthropometric, lipid or nutrient variables. Children with average LDL particle size below the median had higher serum insulin and lower high-density lipoprotein (HDL) cholesterol and apoA-1 concentrations than those with LDL particle size above the median.

CONCLUSION

Our data suggest that many factors related to the development of small, dense LDL particles might have their major impact after the onset of puberty.

Metabolic markers in relation to nutrition and growth in healthy 4-y-old children in Sweden

BACKGROUND

The worldwide increase in overweight and obesity probably involves dietary factors, and early indicators of risk must be identified.

OBJECTIVE

We aimed to analyze metabolic markers in relation to dietary intake and anthropometry in healthy 4-y-old children.

DESIGN

A cross-sectional study of nutritional intake was performed in 95 children by use of 7-d food records. Fasting blood samples were analyzed for glucose, insulin, and lipids.

RESULTS

The study population was representative of Swedish children except that more parents than the average had a university education. The boys' mean energy intake was higher (6.6 +/- 0.75 MJ) than the girls' (5.7 +/- 0.79 MJ). Significant associations were found between the percentage of energy from carbohydrates and that from fat (r = -0.91) and sucrose (r = 0.59). High body mass index was associated with a low percentage of energy from fat (r = -0.32). Serum triacylglycerol, insulin, and the HOMA (homeostatic model assessment) index were higher in girls than in boys. In girls, HOMA beta-cell function was significantly negatively associated with fat intake and serum fasting insulin, and HOMA insulin resistance indexes were significantly associated with the increment in z scores for height and weight from birth to age 4 y. Compared with children with fasting insulin concentrations below the group mean + SD, the children with concentrations above that value were smaller as newborns and had larger increments in growth z scores from birth to age 4 y.

CONCLUSION

In healthy Swedish 4-y-olds from well-educated families, low fat intake was related to high body mass index. Upward weight and height percentile crossings were related to insulin resistance, especially in girls.

Gap analysis of pediatric reference intervals for risk biomarkers of cardiovascular disease and the metabolic syndrome

The childhood obesity epidemic has begun to compromise the health of the pediatric population by promoting premature development of atherosclerosis and the metabolic syndrome (MS), both of which significantly increase the risk of cardiovascular disease (CVD) early in life. As a result, recently, there has been increased recognition of the need to assess and closely monitor children and adolescents for risk factors of CVD and components of the MS. Serum/Plasma biomarkers including total cholesterol, triglycerides, HDL-C, LDL-C, insulin and C-peptide have been used for this purpose for many years. Recently, emerging biomarkers such as apolipoprotein AI, apolipoprotein B, leptin, adiponectin, free fatty acids, and ghrelin have been proposed as tools that provide valuable complementary information to that obtained from traditional biomarkers, if not more powerful predictions of risk. In order for biomarkers to be clinically useful in accurately diagnosing and treating disorders, age-specific reference intervals that account for differences in gender, pubertal stage, and ethnic origin are a necessity. Unfortunately, to date, many critical gaps exist in the reference interval database of most of the biomarkers that have been identified. This review contains a comprehensive gap analysis of the reference intervals for emerging and traditional risk biomarkers of CVD and the MS and discusses the clinical significance and analytical considerations of each biomarker.

Distribution of LDL particle size in a population-based sample of children and adolescents and relationship with other cardiovascular risk factors

BACKGROUND

Smaller, denser LDL particles are associated with an increased risk for cardiovascular diseases (CVD). In youths, data on the distribution of LDL particle size and on its association with other CVD risk factors are limited.

METHODS

We determined LDL peak particle size by nondenaturing 2%-16% gradient gel electrophoresis in a representative sample of 2249 youths 9, 13, and 16 years of age who participated in a school-based survey conducted in 1999 in the province of Quebec, Canada. Standardized clinical measurements and fasting plasma lipid, glucose, and insulin concentrations were available.

RESULTS

The LDL peak particle size distribution was gaussian. The 5th, 50th (median), and 95th percentiles by age and sex were 255.5-258.6, 262.1-263.2, and 268.1-269.5 A, respectively. The prevalence of the small, dense LDL phenotype (LDL peak particle size <or=255 A) was 10% in participants with insulin resistance syndrome (IRS), in contrast to 1% in those without IRS. In a multiple regression analysis, the association of LDL size with other CVD risk factors [apolipoprotein B, HDL-cholesterol (HDL-C), triglyceride (TG), and insulin concentrations, and body mass index] was strongest with TG and HDL-C concentrations: a 1 SD increase in log(e)-transformed TG concentration was associated with a 1.2 A reduction in LDL size, and a 1 SD increase in HDL-C was associated with a 1.1 A increase in LDL size.

CONCLUSIONS

Although the small, dense LDL phenotype is less prevalent in youths than adults, its prevalence is clearly increased in childhood IRS. Metabolic correlates of LDL size are similar in youths and adults.