Filter paper blood spot enzyme linked immunoassay for adiponectin and application in the evaluation of determinants of child insulin sensitivity

Dried blood sample analysis by antibody array across the total testing process

Dried blood samples (DBSs) have many advantages; yet, impediments have limited the clinical utilization of DBSs. We developed a novel volumetric sampling device that collects a precise volume of blood, which overcomes the heterogeneity and hematocrit issues commonly encountered in a traditional DBS card collection as well as allowing for more efficient extraction and processing procedures and thus, more efficient quantitation, by using the entire sample. We also provided a thorough procedure validation using this volumetric DBS collection device with an established quantitative proteomics analysis method, and then analyzed 1000 proteins using this approach in DBSs concomitantly with serum for future consideration of utility in clinical applications. Our data provide a first step in the establishment of a DBS database for the broad application of this sample type for widespread use in clinical proteomic and other analyses applications.

Delivery by caesarean section and offspring adiposity and cardio-metabolic health at ages 6.5, 11.5 and 16 years: results from the PROBIT cohort in Belarus

BACKGROUND

Caesarean delivery has been associated with later adiposity, perhaps via early programming or perhaps because of residual confounding by maternal or birth characteristics.

OBJECTIVES

Examine associations of caesarean delivery with adiposity and cardio-metabolic biomarkers.

METHODS

Observational analysis of 15 069 children in the PROBIT cohort in Belarus. We examined measures of child anthropometry and blood pressure at 6.5, 11.5 and 16 years and fasting blood (11.5 years).

RESULTS

Caesarean-delivered children were slightly heavier at 6.5 (mean BMI 15.8 vs. 15.6 kg/m² ), 11.5 (18.4 vs. 18.2) and 16 years (21.5 vs. 21.3). After adjustment for prenatal characteristics including maternal third trimester BMI, however, we observed no association of caesarean versus vaginal delivery with child BMI (β 0.05 kg/m² ; 95%CI: -0.03, 0.14), sum of skinfolds (0.14 mm; -0.13, 0.42), waist circumference (-0.07 cm; -0.23, 0.10), obesity (OR 0.99; 0.76, 1.29), or systolic (-0.20 mmHg; -0.70, 0.30) or diastolic (-0.17 mmHg, -0.60, 0.26) blood pressure at 6.5 years; results were similar at 11.5 and 16 years. At 11.5 years, we observed a modest association of caesarean delivery with fasting insulin (0.33 mU/L; 0.00, 0.65).

CONCLUSIONS

Caesarean delivery had little or no association with adiposity or related cardio-metabolic biomarkers in childhood. Adjustment for maternal BMI attenuated all outcome effect estimates.

Steps expressed relative to body fat mass predicts body composition and cardiometabolic risk in adults eating ad libitum

Excess body fatness is a consequence of a chronic energy surplus (energy intake is greater than energy expenditure). Given the serious health consequences of excess body fatness, factors that influence energy balance and body composition are increasingly important to understand. Methods - A total of 34 adults between the ages of 19-40 years made a laboratory visit in which height, weight, body composition, and cardiometabolic risk factors were quantified. Participants wore accelerometers for 21-28 days, then returned to the laboratory for a second body composition assessment. Changes in weight and body composition were used to quantify energy balance, and data derived from accelerometers provided markers of physical activity and sedentariness. Results - Of the markers of physical activity that we measured, daily step counts expressed relative to fat mass was most strongly and consistently associated with body fatness and cardiometabolic risk status. Conclusions - Step counts expressed relative to fat mass were strongly associated with body composition and cardiometabolic risk in adults eating ad libitum. Longitudinal interventional studies are necessary to determine the efficacy of step count prescriptions expressed relative to existing and target body fatness and cardiometabolic risk levels for improving weight management and metabolic outcomes.

Little to Give, Much to Gain-What Can You Do With a Dried Blood Spot?

PURPOSE OF REVIEW

Technological advances have allowed dried blood spots (DBS) to be utilized for various measurements, helpful in population-based studies. The following is a review of the literature highlighting the advantages and disadvantages of DBS and describing their use in multiple areas of research.

RECENT FINDINGS

DBS can track pollutant exposure to understand their impact on health. DBS can also be used for (epi-)genetic studies, to measure clinical biomarkers, and to monitor drug adherence. Advantages of DBS include being minimally invasive, requiring low blood volume, and being cost-effective to collect, transport, and store. Disadvantages of DBS include the hematocrit effect, which is related to the viscosity of the blood affecting its spread on to the filter paper, causing a major source of error when assessing concentrations, and the possibility of low DNA volume. Numerous uses for DBS make them an important source of biomaterial but they require additional validation for accuracy and reproducibility.

Dried Blood-Based Protein Profiling Using Antibody Arrays

Dried blood samples have been increasingly considered for clinical applications in recent years. The main disadvantages that limit DBS utility in clinical applications are the small sample volume collected, area bias and homogeneity issues, and sample preparation requirements for the necessary sensitivity and reproducibility required for clinical assessment. The recent advances in antibody array technology overcome the common disadvantages of immunoassay approaches by increasing the multiplex capabilities and decreasing the sample volume requirements as well as minimizing the expense and technical expertise required with many alternative high-density approaches like mass spectrometry.

Eliciting parental support for the use of newborn blood spots for pediatric research

Background

Biomarkers of exposures such as infection or environmental chemicals can be measured in small volumes of blood extracted from newborn dried blood spots (DBS) underscoring their potential utility for population-based research. However, few studies have evaluated the feasibility and utility of this resource; particularly the factors associated with parental consent, and the ability to retrieve banked samples with sufficient remaining volume for epidemiologic research.

Methods

At 8 months postpartum, 5,034 mothers of infants born (2008–2010) in New York (57 counties excluding New York City) were asked to consent for the use of residual DBS for the quantification of cytokines and environmental chemicals. Mothers were part of the Upstate KIDS study, a longitudinal birth cohort designed to evaluate child development through 3 years of age. Information on parental and infant characteristics was obtained from birth certificates and maternal report at 4 months postpartum. Multivariate logistic regression was used to identify factors associated with parental consent and with successful retrieval of DBS.

Results

Sixty-two percent (n = 3125) of parents consented. Factors significantly associated with consent included non-Hispanic ethnicity (odds ratio 2.04; 95 % CI: 1.43–2.94), parity (1.29; 1.05–1.57), maternal obesity (1.42; 1.11–1.80) and reported alcohol use during pregnancy (1.51; 1.12–2.06). However, these associations corresponded to small absolute differences in proportions (4 to 8 %), suggesting that the two groups remained comparable. Infant characteristics such as preterm delivery did not significantly differ by consent status among singletons and only ventilator use (OR 2.39; 95 % CI: 1.06–5.41) remained borderline significant among twins in adjusted analyses. Among consented infants, 99 % had at least one 3.2 mm punch successfully retrieved for biomarker analyses and 84 % had a full DBS circle available.

Conclusion

Parental characteristics varied slightly by consent, and the availability of samples for research purposes was high, demonstrating the feasibility of this resource for population based research.

Newborn Adipokines and Birth Outcomes

BACKGROUND

Adipokines can serve as a measure of adipose tissue activity. Although birthweight correlates with neonatal adiposity, findings for cord blood levels of adipokines and birth outcomes have been conflicted. Therefore, we determined the cross-sectional associations between adipokines measured in newborn dried blood spots (DBS) and birth outcomes.

METHODS

The Upstate KIDS study enrolled mothers and infants from 2008 to 2010. Among infants whose parents consented to the use of residual DBS from newborn screening, 2397 singletons and 1240 twins had adipokine measurements from the Human Obesity Panel (R&D Systems) by Luminex. Odds ratios were estimated by multivariable logistic regression for risk of birth outcomes of preterm delivery (<37 weeks for singletons, <32 for twins) and small-for-gestational age (SGA <10th for singletons and <3rd for twins age- and sex-specific percentiles) by adipokine quintiles. Generalised estimating equations were applied to account for correlations between twins.

RESULTS

Singletons in the lowest compared with the highest quintile of adiponectin were more likely preterm (adjusted odds ratio 3.26; 95% confidence interval [CI] 1.99, 5.34) and SGA (1.81; [95% CI 1.18, 2.77]). Similar associations were observed among twins. Resistin was associated with preterm birth (Q1 vs. Q5: 2.08; [95% CI 1.20, 3.62]) only among singletons. Adipsin had inconsistent associations after adjustment.

CONCLUSIONS

This large population-based study demonstrates that newborn DBS-measured adipokines are associated with birth outcomes, particularly preterm birth and SGA among those with lower adiponectin levels regardless of plurality.

Effects of promoting longer-term and exclusive breastfeeding on cardiometabolic risk factors at age 11.5 years: a cluster-randomized, controlled trial

BACKGROUND

The duration and exclusivity of breastfeeding in infancy have been inversely associated with future cardiometabolic risk. We investigated the effects of an experimental intervention to promote increased duration of exclusive breastfeeding on cardiometabolic risk factors in childhood.

METHODS AND RESULTS

We followed-up children in the Promotion of Breastfeeding Intervention Trial, a cluster-randomized trial of a breastfeeding promotion intervention based on the World Health Organization/United Nations Children's Fund Baby-Friendly Hospital Initiative. In 1996 to 1997, 17 046 breastfeeding mother-infant pairs were enrolled from 31 Belarusian maternity hospitals and affiliated polyclinics (16 intervention versus 15 control sites); 13 879 (81.4%) children were followed up at 11.5 years, with 13 616 (79.9%) who had fasted and did not have diabetes mellitus. The outcomes were blood pressure; fasting insulin, adiponectin, glucose, and apolipoprotein A1; and the presence of metabolic syndrome. Analysis was by intention to treat, accounting for clustering within hospitals/clinics. The intervention substantially increased breastfeeding duration and exclusivity in comparison with the control arm (43% versus 6% and 7.9% versus 0.6% exclusively breastfed at 3 and 6 months, respectively). Cluster-adjusted mean differences at 11.5 years between experimental versus control groups were as follows: 1.0 mm Hg (95% confidence interval, -1.1 to 3.1) for systolic and 0.8 mm Hg (-0.6 to 2.3) for diastolic blood pressure; -0.1 mmol/L (-0.2 to 0.1) for glucose; 8% (-3% to 34%) for insulin; -0.3 μg/mL (-1.5 to 0.9) for adiponectin; and 0.0 g/L (-0.1 to 0.1) for apolipoprotein A1. The cluster-adjusted odds ratio for metabolic syndrome, comparing experimental versus control groups, was 1.21 (0.85 to 1.72).

CONCLUSIONS

An intervention to improve breastfeeding duration and exclusivity among healthy term infants did not influence cardiometabolic risk factors in childhood.

CLINICAL TRIAL REGISTRATION

Current Controlled Trials: ISRCTN37687716 (http://www.controlled-trials.com/ISRCTN37687716). URL: http://clinicaltrials.gov. Unique identifier: NCT01561612.