Marked Influence of Adiposity on Laboratory Biomarkers in a Healthy Cohort of Children and Adolescents.

BACKGROUND: The prevalence of pediatric obesity is increasing worldwide and strongly associates with metabolic abnormalities, including inflammation, insulin resistance, and dyslipidemia. This study assessed the influence of 3 measures of adiposity on levels of routinely assessed biochemical markers in apparently healthy children and adolescents. METHODS: The influence of adiposity on 35 biochemical markers was examined in the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) cohort of healthy children and adolescents by comparing serum biomarker levels between subjects with a normal weight, overweight, and obese body mass index (BMI). The cohort comprised 1332 subjects 5.1 to 19.0 years of age with a BMI ranging from 13.4 to 65.0 kg/m2. The association between each biochemical marker and BMI, waist circumference, and waist-to-height ratio z-scores was assessed, while adjusting for age and sex. Reference intervals were established for all biochemical markers before and after removing overweight/obese subjects. RESULTS: In children and adolescents, levels of 13 routinely assessed biochemical markers, including alanine aminotransferase, apolipoprotein B, complement components 3 and 4, cholinesterase, high sensitivity C-reactive protein, gamma-glutamyl transferase, haptoglobin, high-density lipoprotein cholesterol, iron, transferrin, triglycerides, and uric acid, were significantly different between BMI categories. BMI, waist circumference, and/or waist-to-height ratio were significantly associated with the serum concentration of 24 of the 35 markers examined, after adjusting for age and sex. CONCLUSIONS: Excess adiposity significantly influences circulating levels of routinely assessed laboratory markers, most notably liver enzymes, lipids/lipoproteins, inflammatory markers, and uric acid in children and adolescents. Although it is unknown whether altered biochemical marker levels in subjects with overweight/obesity reflect health or indolent disease, clinicians should be aware of the effect of weight status on several laboratory tests.

Transference of CALIPER pediatric reference intervals to biochemical assays on the Roche cobas 6000 and the Roche Modular P.

OBJECTIVES: The Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) has recently established pediatric age- and sex-specific reference intervals for over 85 biochemical markers on the Abbott Architect system. Previously, CALIPER reference intervals for several biochemical markers were successfully transferred from Abbott assays to Roche, Beckman, Ortho, and Siemens assays. This study further broadens the CALIPER database by performing transference and verification for 52 biochemical assays on the Roche cobas 6000 and the Roche Modular P. DESIGN AND METHODS: Using CLSI C28-A3 and EP9-A2 guidelines, transference of the CALIPER reference intervals was attempted for 16 assays on the Roche cobas 6000 and 36 on the Modular P. Calculated reference intervals were further verified using 100 healthy CALIPER samples. RESULTS: Most assays showed strong correlation between assay systems and were transferable from Abbott to the Roche cobas 6000 (81%) and the Modular P (86%). Bicarbonate and magnesium were not transferable on either system and calcium and prealbumin were not transferable to the Modular P. Of the transferable analytes, 62% and 61% were verified on the cobas 6000 and the Modular P, respectively. CONCLUSIONS: This study extends the utility of the CALIPER database to two additional analytical systems, which facilitates the broad application of CALIPER reference intervals at pediatric centers utilizing Roche biochemical assays. Transference studies across different analytical platforms can later be collectively analyzed in an attempt to develop common reference intervals across all clinical chemistry instruments to harmonize laboratory test interpretation in diagnosis and monitoring of pediatric disease.

Biochemical marker reference values across pediatric, adult, and geriatric ages: establishment of robust pediatric and adult reference intervals on the basis of the Canadian Health Measures Survey.

BACKGROUND: Biological covariates such as age and sex can markedly influence biochemical marker reference values, but no comprehensive study has examined such changes across pediatric, adult, and geriatric ages. The Canadian Health Measures Survey (CHMS) collected comprehensive nationwide health information and blood samples from children and adults in the household population and, in collaboration with the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER), examined biological changes in biochemical markers from pediatric to geriatric age, establishing a comprehensive reference interval database for routine disease biomarkers. METHODS: The CHMS collected health information, physical measurements, and biosamples (blood and urine) from approximately 12 000 Canadians aged 3-79 years and measured 24 biochemical markers with the Ortho Vitros 5600 FS analyzer or a manual microplate. By use of CLSI C28-A3 guidelines, we determined age- and sex-specific reference intervals, including corresponding 90% CIs, on the basis of specific exclusion criteria. RESULTS: Biochemical marker reference values exhibited dynamic changes from pediatric to geriatric age. Most biochemical markers required some combination of age and/or sex partitioning. Two or more age partitions were required for all analytes except bicarbonate, which remained constant throughout life. Additional sex partitioning was required for most biomarkers, except bicarbonate, total cholesterol, total protein, urine iodine, and potassium. CONCLUSIONS: Understanding the fluctuations in biochemical markers over a wide age range provides important insight into biological processes and facilitates clinical application of biochemical markers to monitor manifestation of various disease states. The CHMS-CALIPER collaboration addresses this important evidence gap and allows the establishment of robust pediatric and adult reference intervals.

Complex reference values for endocrine and special chemistry biomarkers across pediatric, adult, and geriatric ages: establishment of robust pediatric and adult reference intervals on the basis of the Canadian Health Measures Survey.

BACKGROUND: Defining laboratory biomarker reference values in a healthy population and understanding the fluctuations in biomarker concentrations throughout life and between sexes are critical to clinical interpretation of laboratory test results in different disease states. The Canadian Health Measures Survey (CHMS) has collected blood samples and health information from the Canadian household population. In collaboration with the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER), the data have been analyzed to determine reference value distributions and reference intervals for several endocrine and special chemistry biomarkers in pediatric, adult, and geriatric age groups. METHODS: CHMS collected data and blood samples from thousands of community participants aged 3 to 79 years. We used serum samples to measure 13 immunoassay-based special chemistry and endocrine markers. We assessed reference value distributions and, after excluding outliers, calculated age- and sex-specific reference intervals, along with corresponding 90% CIs, according to CLSI C28-A3 guidelines. RESULTS: We observed fluctuations in biomarker reference values across the pediatric, adult, and geriatric age range, with stratification required on the basis of age for all analytes. Additional sex partitions were required for apolipoprotein AI, homocysteine, ferritin, and high sensitivity C-reactive protein. CONCLUSIONS: The unique collaboration between CALIPER and CHMS has enabled, for the first time, a detailed examination of the changes in various immunochemical markers that occur in healthy individuals of different ages. The robust age- and sex-specific reference intervals established in this study provide insight into the complex biological changes that take place throughout development and aging and will contribute to improved clinical test interpretation.

Complex biological profile of hematologic markers across pediatric, adult, and geriatric ages: establishment of robust pediatric and adult reference intervals on the basis of the Canadian Health Measures Survey.

BACKGROUND: In a collaboration between the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) and the Canadian Health Measures Survey (CHMS), we determined reference value distributions using an a priori approach and created a comprehensive database of age- and sex-stratified reference intervals for clinically relevant hematologic parameters in a large household population of children and adults. METHODS: The CHMS collected data and blood samples from 11 999 respondents aged 3-79 years. Hematology markers were measured with either the Beckman Coulter HmX or Siemens Sysmex CA-500 Series analyzers. After applying exclusion criteria and removing outliers, we determined statistically relevant age and sex partitions and calculated reference intervals, including 90% CIs, according to CSLI C28-A3 guidelines. RESULTS: Hematology marker values showed dynamic changes from childhood into adulthood as well as between sexes, necessitating distinct partitions throughout life. Most age partitions were necessary during childhood, reflecting the hematologic changes that occur during growth and development. Hemoglobin, red blood cell count, hematocrit, and indices (mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration) increased with age, but females had lower hemoglobin and hematocrit starting at puberty. Platelet count gradually decreased with age and required multiple sex partitions during adolescence and adulthood. White blood cell count remained relatively constant over life, whereas fibrinogen increased slightly, requiring distinct age and sex partitions. CONCLUSIONS: The robust dataset generated in this study has allowed observation of dynamic biological profiles of several hematology markers and the establishment of comprehensive age- and sex-specific reference intervals that may contribute to accurate monitoring of pediatric, adult, and geriatric patients.

CLSI-based transference of CALIPER pediatric reference intervals to Beckman Coulter AU biochemical assays.

OBJECTIVE: The CALIPER program has established a comprehensive database of pediatric reference intervals using largely the Abbott ARCHITECT biochemical assays. To expand clinical application of CALIPER reference standards, the present study is aimed at transferring CALIPER reference intervals from the Abbott ARCHITECT to Beckman Coulter AU assays. DESIGN AND METHODS: Transference of CALIPER reference intervals was performed based on the CLSI guidelines C28-A3 and EP9-A2. The new reference intervals were directly verified using up to 100 reference samples from the healthy CALIPER cohort. RESULTS: We found a strong correlation between Abbott ARCHITECT and Beckman Coulter AU biochemical assays, allowing the transference of the vast majority (94%; 30 out of 32 assays) of CALIPER reference intervals previously established using Abbott assays. Transferred reference intervals were, in general, similar to previously published CALIPER reference intervals, with some exceptions. Most of the transferred reference intervals were sex-specific and were verified using healthy reference samples from the CALIPER biobank based on CLSI criteria. It is important to note that the comparisons performed between the Abbott and Beckman Coulter assays make no assumptions as to assay accuracy or which system is more correct/accurate. CONCLUSION: The majority of CALIPER reference intervals were transferrable to Beckman Coulter AU assays, allowing the establishment of a new database of pediatric reference intervals. This further expands the utility of the CALIPER database to clinical laboratories using the AU assays; however, each laboratory should validate these intervals for their analytical platform and local population as recommended by the CLSI.

Advances in Pediatric Reference Intervals for Biochemical Markers: Establishment of the Caliper Database in Healthy Children and Adolescents.

Clinical laboratory reference intervals provide valuable information to medical practitioners in their interpretation of quantitative laboratory test results, and therefore are critical in the assessment of patient health and in clinical decision-making. The reference interval serves as a health-associated benchmark with which to compare an individual test result. Unfortunately, critical gaps currently exist in accurate and up-to-date pediatric reference intervals for accurate interpretation of laboratory tests performed in children and adolescents. These critical gaps in the available laboratory reference intervals have the clear potential of contributing to erroneous diagnosis or misdiagnosis of many diseases. To address these important gaps, several initiatives have begun internationally by a number of bodies including the KiGGS initiative in Germany, the Aussie Normals in Australia, the AACC-National Children Study in USA, the NORICHILD Initiative in Scandinavia, and the CALIPER study in Canada. In the present article, we will review the gaps in pediatric reference intervals, challenges in establishing pediatric norms in healthy children and adolescents, and the major contributions of the CALIPER program to closing the gaps in this crucial area of pediatric laboratory medicine. We will also discuss the recently published CALIPER reference interval database (www.caliperdatabase.com) developed to provide comprehensive age and gender specific pediatric reference intervals for a larger number of biochemical markers, based on a large and diverse healthy children cohort. The CALIPER database is based on a multiethnic population examining the influence of ethnicity on laboratory reference intervals. Thus the database has proved to be of global benefit and is being adopted by hospital laboratories worldwide.

Knockdown of Pex11ß reveals its pivotal role in regulating peroxisomal genes, numbers, and ROS levels in Xenopus laevis A6 cells.

Peroxisomes are organelles that are ubiquitously found in all eukaryotic cells. Enzymes within their lumen are responsible for a variety of processes including the metabolism of fatty acids and eradication (neutralization) of free radicals. Peroxisomes are dynamic organelles, able to alter their numbers in response to a variety of different metabolic and cell-specific cues. Changes in peroxisome numbers can occur through division of preexisting peroxisomes or through de novo biogenesis from the ER. Proteins such as the Pex11 family of peroxins have been implicated as regulatory factors involved in peroxisome division. Division of peroxisomes involves elongation and membrane constriction followed by fission, which requires Pex11ß. The regulation of peroxisome numbers in different cell types and tissues is variable and poorly understood. Here, we examine how knockdown of Pex11ß affects peroxisomal genes, proteins, and peroxisome numbers in A6 kidney epithelial cells derived from Xenopus laevis. Pex11ß morpholino use subsequently decreased mRNA levels of Pex1, PMP70, and PPARγ. Moreover, the Pex11ß morpholino decreased PMP70 protein levels and PMP70-positive structures. Furthermore, the marker GFP-SKL revealed fewer peroxisome-like structures. These decreases resulted in increased levels of H2O2 and cellular and mitochondrial reactive oxygen species as measured by Amplex Red, DCFDA, and MitoTracker assays, respectively.

PEX11ß induces peroxisomal gene expression and alters peroxisome number during early Xenopus laevis development.

BACKGROUND: Peroxisomes are organelles whose roles in fatty acid metabolism and reactive oxygen species elimination have contributed much attention in understanding their origin and biogenesis. Many studies have shown that de novo peroxisome biogenesis is an important regulatory process, while yeast studies suggest that total peroxisome numbers are in part regulated by proteins such as Pex11, which can facilitate the division of existing peroxisomes. Although de novo biogenesis and divisions are likely important mechanisms, the regulation of peroxisome numbers during embryonic development is poorly understood. Peroxisome number and function are particularly crucial in oviparous animals such as frogs where large embryonic yolk and fatty acid stores must be quickly metabolized, and resulting reactive oxygen species eliminated. Here we elucidate the role of Pex11ß in regulating peroxisomal gene expression and number in Xenopus laevis embryogenesis. RESULTS: Microinjecting haemagglutinin (HA) tagged Pex11ß in early embryos resulted in increased RNA levels for peroxisome related genes PMP70 and catalase at developmental stages 10 and 20, versus uninjected embryos. Catalase and PMP70 proteins were found in punctate structures at stage 20 in control embryos, whereas the injection of ectopic HA-Pex11ß induced their earlier localization in punctate structures at stage 10. Furthermore, the peroxisomal marker GFP-SKL, which was found localized as peroxisome-like structures at stage 20, was similarly found at stage 10 when co-microinjected with HA-Pex11ß. CONCLUSIONS: Overexpressed Pex11ß altered peroxisomal gene levels and induced the early formation of peroxisomes-like structures during development, both of which demonstrate that Pex11ß may be a key regulator of peroxisome number in early Xenopus embryos.