The ELISA is the mainstay for sensitive and quantitative detection of protein analytes. Despite its utility, ELISA is time-consuming, resource-intensive, and infrastructure-dependent, limiting its availability in resource-limited regions. Here, we describe a self-contained immunoassay platform (the "D4 assay") that converts the sandwich immunoassay into a point-of-care test (POCT). The D4 assay is fabricated by inkjet printing assay reagents as microarrays on nanoscale polymer brushes on glass chips, so that all reagents are "on-chip," and these chips show durable storage stability without cold storage. The D4 assay can interrogate multiple analytes from a drop of blood, is compatible with a smartphone detector, and displays analytical figures of merit that are comparable to standard laboratory-based ELISA in whole blood. These attributes of the D4 POCT have the potential to democratize access to high-performance immunoassays in resource-limited settings without sacrificing their performance.

We provide an in-depth review of the role of androgens in male maturation and development, from the fetal stage through adolescence into emerging adulthood, and discuss the treatment of disorders of androgen production throughout these time periods. Testosterone, the primary androgen produced by males, has both anabolic and androgenic effects. Androgen exposure induces virilization and anabolic body composition changes during fetal development, influences growth and virilization during infancy, and stimulates development of secondary sexual characteristics, growth acceleration, bone mass accrual, and alterations of body composition during puberty. Disorders of androgen production may be subdivided into hypo- or hypergonadotropic hypogonadism. Hypogonadotropic hypogonadism may be either congenital or acquired (resulting from cranial radiation, trauma, or less common causes). Hypergonadotropic hypogonadism occurs in males with Klinefelter syndrome and may occur in response to pelvic radiation, certain chemotherapeutic agents, and less common causes. These disorders all require testosterone replacement therapy during pubertal maturation and many require lifelong replacement. Androgen (or gonadotropin) therapy is clearly beneficial in those with persistent hypogonadism and self-limited delayed puberty and is now widely used in transgender male adolescents. With more widespread use and newer formulations approved for adults, data from long-term randomized placebo-controlled trials are needed to enable pediatricians to identify the optimal age of initiation, route of administration, and dosing frequency to address the unique needs of their patients.

The prevalence of pediatric obesity in the United States is nearly 17%. Most cases are “exogenous”, resulting from excess energy intake relative to energy expenditure over a prolonged period of time. However, some cases of obesity are “endogenous”, associated with hormonal, genetic, or syndromic disorders such as hypothyroidism, Cushing’s syndrome, growth hormone deficiency, defective leptin signaling, mutations in the melanocortin 4 receptor, and Prader-Willi and Bardet-Biedl syndromes. This article reviews the hormonal, monogenic, and syndromic causes of childhood obesity and identifies critical features that distinguish “endogenous” obesity disorders from the more common exogenous obesity. Findings that raise suspicion for endogenous obesity include onset in infancy, lack of satiety, poor linear growth, dysmorphic features, and cognitive dysfunction. Selection and interpretation of appropriate laboratory tests and indications for subspecialist referral are also discussed.

Eating disorders and disturbed body image have been reported in individuals with cystic fibrosis (CF) and may contribute to poor weight gain, reduced lung function and increased mortality. CF individuals often look and feel different from their peers and bear the additional burden of body-altering side effects of treatment. As a result, the impact of disorders such as binge eating, anorexia nervosa, and bulimia nervosa may adversely affect the social, emotional, and physical development of those with CF. Multiple risk factors may contribute to the development of an eating disorder in CF. Growth failure is affected by the physical impairments of CF, including pancreatic insufficiency, high energy demands, respiratory infections, and delayed and stunted growth and puberty. Psychological factors, such as CF associated depression and anxiety, intense focus on BMI, lack of control in a chronic disease, and preoccupation with morbidity and mortality, likely further contribute. Exercise inefficiency, secondary to poor lung function, low BMI and pulmonary exacerbations, and the potential for medication manipulation are also additional risk factors. The intense scrutiny around BMI may lead to a poor relationship with food, including disordered eating habits, abnormal mealtime behaviors, and stressful caregiver-patient interactions regarding meals. This further contributes to a discrepancy between ideal CF nutritional standards and the reality of the challenges of appropriate daily energy intake for an individual with CF. It is imperative that CF providers are equipped to identify potential eating disorders and disturbed body image in their CF patients. Improved screening and monitoring practices should be developed and implemented, with multidisciplinary support from all CF care team members, including dietitians, mental health professionals, and social workers, to best support holistic care and optimize outcomes. Increased attention to these concerns may help reduce CF related morbidity and mortality.

Background: To provide energy for cardiopulmonary function and maintenance of blood glucose, acute aerobic exercise induces lipolysis, fatty acid oxidation (FAO), glycolysis, and glycogenolysis/gluconeogenesis. These adaptations are mediated by increases in cortisol, growth hormone (GH), and catecholamines and facilitated by a decline in insulin. Branched-chain amino acids (BCAA) also undergo catabolism during intense exercise. Here, we investigated the relationship between BCAA catabolism and metrics of cardiopulmonary function in healthy, well-developed, mature adolescent athletes undergoing an acute bout of maximal aerobic exercise.Hypothesis: We hypothesized: (a) acute maximal exercise in adolescents induces lipolysis, FAO, and BCAA catabolism associated with increases in GH and cortisol and a reduction in insulin; (b) increases in GH are associated with increases in ghrelin; and (c) metrics of cardiopulmonary function (aVO2, rVO2, aVO2/HRmax) following maximal exercise correlate with increases in GH secretion, FAO, and BCAA catabolism.Methods: Blood samples before and after maximal cardiopulmonary exercise in 11 adolescent athletes were analyzed by tandem-mass spectrometry. Paired, two-tailed student's t-tests identified significant changes following exercise. Linear regression determined if pre-exercise metabolite levels, or changes in metabolite levels, were associated with aVO2, rVO2, and aVO2/HRmax. Sex and school of origin were included as covariates in all regression analyses.Results: Following exercise there were increases in GH and cortisol, and decreases in ghrelin, but no changes in glucose or insulin concentrations. Suggesting increased lipolysis and FAO, the levels of glycerol, ketones, β-hydroxybutyrate, and acetylcarnitine concentrations increased. Pyruvate, lactate, alanine, and glutamate concentrations also increased. Plasma concentrations of valine (a BCAA) declined (p = 0.002) while valine degradation byproducts increased in association with decreases in urea cycle amino acids arginine and ornithine. Metrics of cardiopulmonary function were associated with increases in propionylcarnitine (C3, p = 0.013) and Ci4-DC/C4-DC (p < 0.01), byproducts of BCAA catabolism.Conclusions: Induction of lipolysis, FAO, gluconeogenesis, and glycogenolysis provides critical substrates for cardiopulmonary function during exercise. However, none of those pathways were significantly associated with metrics of cardiopulmonary function. The associations between rVO2, and aVO2/HRmax and C3 and Ci4-DC/C4-DC suggest that the cardiopulmonary response to maximal exercise in adolescents is linked to BCAA utilization and catabolism.