A 6-Week-Old Boy With Irritability and Abdominal Distension.

A 6-week-old boy is brought to the hospital for fussiness and abdominal distension. He was febrile on presentation and was admitted to the hospital for further evaluation. On subsequent examinations, he continued to demonstrate abdominal distension and tenderness to palpation. Ultrasonography of the abdomen was performed and revealed a heterogeneous liver mass. With further diagnostics, a diagnosis was made and treatment initiated, with the infant experiencing resolution of his symptoms. Our panel of experts first discuss the management of an infant with abdominal distension, then discuss the evaluation of a liver mass in an infant, including oncologic, vascular, and infectious etiologies.

An Adolescent Boy With Hypoxia, Microscopic Hematuria, and Hypertension.

A 13-year-old boy presented with hypoxia, microscopic hematuria, and elevated blood pressures. Persistent microscopic hematuria and hypertension led to investigation of glomerular and non-glomerular causes of hematuria. After reviewing his clinical course, family history, and laboratory testing, an additional test was sent, revealing the diagnosis.

Biological mechanisms that promote weight regain following weight loss in obese humans.

Weight loss dieting remains the treatment of choice for the vast majority of obese individuals, despite the limited long-term success of behavioral weight loss interventions. The reasons for the near universal unsustainability of behavioral weight loss in [formerly] obese individuals have not been fully elucidated, relegating researchers to making educated guesses about how to improve obesity treatment, as opposed to developing interventions targeting the causes of weight regain. This article discusses research on several factors that may contribute to weight regain following weight loss achieved through behavioral interventions, including adipose cellularity, endocrine function, energy metabolism, neural responsivity, and addiction-like neural mechanisms. All of these mechanisms are engaged prior to weight loss, suggesting that these so called "anti-starvation" mechanisms are activated via reductions in energy intake, rather than depletion of energy stores. Evidence suggests that these mechanisms are not necessarily part of a homeostatic feedback system designed to regulate body weight, or even anti-starvation mechanisms per se. Although they may have evolved to prevent starvation, they appear to be more accurately described as anti-weight loss mechanisms, engaged with caloric restriction irrespective of the adequacy of energy stores. It is hypothesized that these factors may combine to create a biological disposition that fosters the maintenance of an elevated body weight and works to restore the highest sustained body weight, thus precluding the long-term success of behavioral weight loss. It may be necessary to develop interventions that attenuate these biological mechanisms in order to achieve long-term weight reduction in obese individuals.