Obesity: genetic, molecular, and environmental aspects.

Obesity has emerged as one of the most serious public health concerns in the 21st century. Obese children tend to become obese adults. The dramatic rise in pediatric obesity closely parallels the rapid increase in the prevalence of adult obesity. As overweight children become adults they face the multitude of health problems associated with obesity at younger ages. The morbidity and mortality associated with obesity continue to increase. Obesity is one of the leading causes of preventable death. Complications of obesity include cardiovascular risks, hypertension, dyslipidemia, endothelial dysfunction, type 2 diabetes mellitus and impaired glucose tolerance, acanthosis nigricans, hepatic steatosis, premature puberty, hypogonadism and polycystic ovary syndrome, obstructive sleep disorder, orthopedic complications, cholelithiasis and pseudotumor cerebri. Genetic and molecular and environmental factors play an important role in the assessment and management of obesity.

Obesity in children.

The alarming increase in obesity in children has become a major health problem in the increased incidence of type 2 diabetes as well as other complications including cardiovascular diseases, hepatic disorders, skeletal abnormalities, malignancies and in particular psychological disorders. Mechanisms of appetite and energy metabolism are mediated through hormones leptin and ghrelin, and neuropeptide-Y neurons as well as genetic factors. Control of obesity is largely through appetite control and physical exercise.

Pathogenesis of cardiac conduction disorders in children genetic and histopathologic aspects.

Fetal dysrhythmias are usually transient. Abnormal fetal rates and rhythms during labor are "functional." Fetal dysrhythmias may be associated with congenital heart disease and fetal hydrops. Bradycardia is usually related to fetal distress; supraventricular tachycardia, atrial flutter, and atrial fibrillation may be associated with severe congestive heart failure. Ventricular fibrillation is rare in the fetus and infant and is usually associated with myocardial necrosis with perimembranous septal defect; the nonbranching atrioventricular (AV) bundle may have an aberrant position and result in cardiac arrhythmia. Wolff-Parkinson-White syndrome with conduction abnormalities and left ventricular hypertrophy (LVH) is due to an accessory pathway that bypasses the AV sulcus and results in faster conduction. Carnitine deficiency may be primary or secondary and may result in cardiac arrhythmia. Histiocytoid cardiomyopathy is characterized by cardiomegaly, incessant ventricular tachycardia, and frequently sudden death. Arrhythmogenic right ventricular dysplasia (ARVD) results in ventricular tachycardia and left bundle branch block. Noncompaction of the left ventricle predisposes to potentially fatal arrhythmias. Long Q-T syndromes (LQTS) are a heterogeneous group of disorders with many genetic mutations. Brugada syndrome is an autosomal dominant trait with right bundle branch block and ST elevation. Barth syndrome is an X-linked disorder with dilated cardiomyopathy, cyclic neutropenia and skeletal myopathy. Hypertrophic cardiomyopathy in infancy may be related to metabolic diseases, particularly glycogen storage diseases; the familial form predisposes to sudden death. Arrhythmias following cardiac surgery may occur after closure of a ventricular septal defect (VSD) or damage to the conduction system.

An approach to the diagnosis of metabolic diseases.

Inborn metabolic errors, which are not common, may have significant implications for patients. Those patients with such errors who have acute life-threatening symptoms must be treated immediately, and specimens for analysis should be obtained and saved for later analysis during the critical stage. Many infants and children seen with acute symptoms are the ones most likely to have treatable diseases. At a more leisurely pace, other inborn errors can be diagnosed to provide appropriate counseling and prognosis.

The effects of dietary nucleotides on intestinal blood flow in preterm infants.

Nucleotides (NT) are reported to affect development of the immune and gastrointestinal systems, and they are currently added to most term infant formulas. In the present study, dietary NT effects on superior mesenteric artery blood flow were investigated. Formula-fed preterm infants were studied once with a 20 kcal/oz. term infant formula containing 80.6 mg/L of NT (NT+), and once with the same formula with no added NT (NT-) (n = 20, gestational age 28.0 +/- 2.2 wk). A reference group of preterm infants fed human milk was also studied (n = 20, gestational age 29.0 +/- 1.6 wk). Superior mesenteric artery blood flow velocities (BFV) were measured by Doppler ultrasound 15 min before and 30, 60, and 90 min after the start of the feed. BFV rose in all infants from baseline to 30 min after feed initiation, and progressively declined thereafter in infants fed NT- or human milk. However, NT+ feedings were associated with a minimal change in BFV between 60 and 90 min. As a result, the difference in blood flow velocities between baseline and 90 min was significantly greater with the NT+ versus the NT- feedings for the mean, peak systolic, and end diastolic velocities (p = 0.03, 0.05, and 0.03, respectively). BFV after the NT- and human milk feedings were similar. These data suggest that orally administered NT are associated with effects on the intestinal vasculature.