Regional distribution and metabolic effect of PCSK9 insLEU and R46L gene mutations and apoE genotype.

Background: Natural loss-of-function mutations in the proprotein convertase subtilisin/kexin type-9 gene (PCSK9) are associated with lower cholesterol and cardiovascular risk. Because a founder effect exists in French Canadians for many lipid-related genes, we sought to investigate PCSK9 mutations and associated variables in this population. We also investigated the combined effect of PCSK9 mutations and the apolipoprotein E (apoE) polymorphism on metabolic variables.

Is the obesity epidemic worsening the cardiovascular risk factor profile of children? Evidence from two Québec samples measured 10 years apart.

Background: The impact of the obesity epidemic on cardiovascular health in young people is of increasing concern. However, data on secular trends in CVD indicators are outdated and mixed.

Methods: This study compared lipid profiles and insulin of 9-10 year olds in 2008 (n = 605) and 1999 (n = 779).

Association between different growth curve definitions of overweight and obesity and cardiometabolic risk in children.

Background: Overweight and obesity in young people are assessed by comparing body mass index (BMI) with a reference population. However, two widely used reference standards, the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) growth curves, have different definitions of overweight and obesity, thus affecting estimates of prevalence. We compared the associations between overweight and obesity as defined by each of these curves and the presence of cardiometabolic risk factors.

[Importance of vitamin D in insulin resistance].

Beyond its classical role in bone metabolism, fundamental and epidemiological studies suggest that vitamin D is also involved in immunity and cell proliferation. Indeed, 25-hydroxyvitamin D 1alpha-hydroxylase and specific receptors for 1,25-dihydroxyvitamin D, the hormonal form of vitamin D, have been found in a variety of organs and tissues, such as the liver, epidermis, thymus, small intestine and pancreas. This brief review examines the results of in vitro, animal and clinical studies suggesting a role of vitamin D in glucose homeostasis.

Vitamin D status is modestly associated with glycemia and indicators of lipid metabolism in French-Canadian children and adolescents.

In addition to its recognized role in bone health, recent studies point to vitamin D functions in other tissues, including the pancreas. We tested the association between the vitamin D status and glucose and lipid homeostasis in a school-based, cross-sectional survey of a representative sample of youth. We measured fasting plasma insulin, glucose, total cholesterol (TC), triglycerides (TG), HDL cholesterol (HDL-C) apolipoproteins (apo) A1 and B, and 25-hydroxyvitamin D [25(OH)D] concentrations in 878 boys and 867 girls.

Plasma PCSK9 is associated with age, sex, and multiple metabolic markers in a population-based sample of children and adolescents.

Background: Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a protein convertase that posttranslationally promotes the degradation of the low-density lipoprotein receptor (LDLR) in hepatocytes and increases plasma LDL cholesterol (LDL-C). Heterozygote gain-of-function mutations of PCSK9 are associated with the familial hypercholesterolemia phenotype, whereas loss-of-function variants are associated with reduced LDL-C concentrations and lower coronary risk. Plasma PCSK9 correlates with body mass index, triglyceridemia, total cholesterol, and LDL-C in adults, but no data are available in youth.

Association between insulin, leptin, adiponectin and blood pressure in youth.

Objective: To examine whether insulin, leptin and adiponectin are independent correlates of blood pressure (BP) in a large population-based sample of children and adolescents.

Methods: We studied 655 boys and 667 girls aged 9, 13 and 16 years who participated in the Quebec Child and Adolescent Health and Social Survey, a province-wide school-based survey conducted in 1999.

Results: Strong, positive univariate associations between BMI, insulin and leptin Z-scores, and both systolic and diastolic BP were found in both sexes.

Newborn screening for sickle cell disease: A 1988-2003 Quebec experience.

Background: Sickle cell disease (SCD) is associated with significant mortality and morbidity that can be decreased by neonatal diagnosis. Although 44 American states have implemented such programs, there are no provincially funded universal or targeted newborn screening programs for SCD in Canada.

Objective: To report a critical appraisal of a hospital-based neonatal screening program targeting at-risk infants over a 15-year period.

13C-labeled mixed triglyceride breath test (13C MTG-BT) in healthy children and children with cystic fibrosis (CF) under pancreatic enzyme replacement therapy (PERT): a pilot study.

The MTG-BT estimates the hydrolysis of triacyl-glycerols by pancreatic lipase, and appears attractive for monitoring exogenous lipase requirements in patients with exocrine pancreatic insufficiency. To assess the test's discrimination capacity and repeatability, 9 CF patients with PERT and 10 healthy children underwent the (13)C-MTG-BT twice, at a 2- to 4-week interval. The test distinguished well between patients with severe exocrine pancreatic insufficiency (SEPI) and healthy subjects.

Prevalence of cardiometabolic risk factors by weight status in a population-based sample of Quebec children and adolescents.

Background: There are few data on the prevalence of cardiometabolic risk factors in population-based samples of overweight and obese youth.

Objectives: To compare the prevalence of individual and multiple cardiometabolic risk factors across body mass index (BMI) categories in a population-based sample of youth.

Methods: In 1999, a school-based survey of a provincially representative sample of youth nine, 13 and 16 years of age was conducted in Quebec (1778 boys, 1835 girls).

Low vitamin D status in a representative sample of youth from Québec, Canada.

Background: Adequate vitamin D status is important for bone growth and mineralization and has been implicated in the regulation of autoimmunity, metabolic function, and cancer prevention. There are no reports of population-based studies on the vitamin D status of Canadian youth, a population with mandatory fortification of foods.

Methods: We measured plasma 25-hydroxyvitamin D [25(OH)D], the best indicator of vitamin D status, in a school-based cross-sectional sample of representative French Canadian youth (n = 1753) ages 9, 13, and 16 years living in Québec (latitude: 45 degrees-48 degrees N).

Association between cigarette smoking and C-reactive protein in a representative, population-based sample of adolescents.

Although related to inflammatory markers in adults, little is known about the association between cigarette smoking and C-reactive protein (CRP) in adolescent smokers. We examined the association between high-sensitivity CRP (hs-CRP) concentrations and smoking in youth. We used data from a cross-sectional, province-wide survey of a representative sample of youth conducted in Quebec, Canada, in 1999.

Gap analysis of pediatric reference intervals related to thyroid hormones and the growth hormone-insulin growth factor axis.

Efficacy of laboratory medicine in assisting attending physicians in their diagnostic and follow-up endeavors is intimately linked to an access to meaningful and reliable reference values. Pediatrics is particularly sensitive to this problem as the processes, associated with growth and development, are imposing rapid discontinuous changes on the physiology of the individuals. Some developmental stages are more critical than others.

Congenital hypothyroidism: from paracelsus to molecular diagnosis.

Endemic cretinism was noted in alpine Europe as early as the 13th century. However, it was only in 1848 that a commission, sponsored by the King of Sardinia, first formally demonstrated its link to goiter. An important landmark was the publication of a report in 1871 describing several cases of nongoitrous hypothyroidism that were clearly distinguished from the endemic form of the disease, for which the author suggested the designation of "sporadic cretinism.

WITHDRAWN: Clinical Chemistry: 50 years of stimulating changes and more to come.

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Adiponectin, adiposity, and insulin resistance in children and adolescents.

Context: Determinants of adiponectin and its association with insulin resistance (IR) are less well studied in youth than in adults.

Objectives: The objective of the study was to describe, in youth, the age- and sex-specific distribution of adiponectin concentrations and the association with demographic, anthropometric, and lifestyle factors, parental diabetes, and markers of IR.

Design, Setting, Participants: We studied 1632 French Canadian youth aged 9, 13, and 16 yr who participated in the Québec Child and Adolescent Health and Social Survey, a province-wide, school-based survey conducted in 1999.

Neonate capillary blood gas reference values.

Objectives: Because biological data are instrument-dependent and because technology has evolved over the last two decades, the published capillary blood reference values for blood gases, lactate, ionized calcium (iCa) and glucose may not reflect the present day situation. Hence, we report such values for healthy term neonates at 48 +/- 12 h of life.

Design And Methods: The Institution Ethics Review Board for Research on Human Subjects has accepted the protocol.

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.

Oral vitamin A, E and D supplementation of pre-term newborns either breast-fed or formula-fed: a 3-month longitudinal study.

Background: In contrast to the studies of vitamin A and E status in children, adolescents and adults, information on preterm infants is scarce. In the present investigation we examined the vitamin A, D and E status of pre-term infants at birth, and verified whether, at 1 and 3 months, breast or formula feeding affected the plasma concentration of those vitamins while being supplemented with Uvesterol ADEC.

Patients And Methods: In this prospective study, 2 groups of consecutively recruited preterm newborns fed either breast milk or formula received 3000 IU of vitamin A, 5 IU of vitamin E and 1000 IU of vitamin D daily.

Twenty years later: a reevaluation of the contribution of plasma thyroglobulin to the diagnosis of thyroid dysgenesis in infants with congenital hypothyroidism.

Background: The definition of the type of thyroid dysgenesis in congenital hypothyroidism (CH), ectopy, or athyreosis is important for monitoring patients and for genetic investigations. We have recently encountered infants who in spite of undetectable Technetium uptake on scintigraphy had biochemical results making athyreosis unlikely.

Objective: To reevaluate the utility of plasma thyroglobulin (Tg) in this clinical context using new sensitive Tg assays.

C-reactive protein and features of the metabolic syndrome in a population-based sample of children and adolescents.

Background: C-Reactive protein (CRP) is a risk marker for type 2 diabetes and cardiovascular diseases. In youth, limited data are available on the distribution of high-sensitivity CRP as well as on its association with components of the metabolic syndrome.

Methods: In 1999, we conducted a school-based survey of a representative sample of youths 9, 13, and 16 years of age in the province of Quebec, Canada.

Reference intervals for free thyroxine, total triiodothyronine, thyrotropin and thyroglobulin for Quebec newborns, children and teenagers.

Objective: Paediatric reference values, although essential for interpreting patients' results, are scarce. Moreover, they are often population- and instrument-dependent. We have measured free thyroxine (Free T(4)), total triiodothyronine (Total T(3)), thyroglobulin (Tg) and thyrotropin (TSH) in samples obtained from groups of newborns, children and adolescents.

The Québec Child and Adolescent Health and Social Survey: design and methods of a cardiovascular risk factor survey for youth.

Background: Although atherosclerosis begins in childhood, there are no recent Canadian data on cardiovascular risk factors in provincially or nationally representative samples of youth.

Objective: To describe the design and methods of the 1999 Québec Child and Adolescent Health and Social Survey, which assessed the prevalence and distribution of risk factors in a representative sample of Québec youth.

Methods: School-based, multistage, cluster sampling survey of youth aged nine, 13 and 16 years.

Distribution of fasting plasma insulin, free fatty acids, and glucose concentrations and of homeostasis model assessment of insulin resistance in a representative sample of Quebec children and adolescents.

Background: Plasma fasting insulin and the homeostasis model assessment of insulin resistance (HOMA-IR) are markers of IR, which, at least in part, mediates the relation of obesity to increased cardiovascular risk. Increased free fatty acids (FFAs) may be involved in the pathogenesis of IR. Our objectives were to describe the distributions of fasting plasma insulin, glucose, and FFAs and HOMA-IR in youth and to assess the relationship between FFAs and markers of IR.