Advances in pediatrics
-
Advances in pediatrics · Jan 1987
ReviewNew genetic defects in mitochondrial fatty acid oxidation and carnitine deficiency.
There are now nine inherited diseases that have been identified in the pathway of mitochondrial fatty acid oxidation, including LCAD, MCAD, SCAD, and HMG-CoA lyase deficiencies, two forms each of CPT and MAD deficiencies and an incompletely characterized disorder of primary carnitine deficiency. The varied range of clinical manifestations in this new group of diseases should attract the attention not only of general pediatricians (coma, hypoglycemia) but also of pediatric subspecialists in neurology (myopathy), cardiology (cardiomyopathy), and gastroenterology (fatty liver), as well as genetics and metabolism. The presenting features of the genetic defects in fatty acid oxidation fit well with the concept that fatty acid oxidation plays a major role in energy production during prolonged fasting and in working cardiac and skeletal muscle. ⋯ These manifestations presumably reflect the requirement of working cardiac and skeletal muscle for energy supplied from fatty acid oxidation. In two of the disorders, SCAD deficiency and the severe form of MAD deficiency, chronic CNS toxicity is a dominant feature. The severe effects on the brain in these two disorders may reflect the fact that short-chain fatty acids more readily cross the blood-brain barrier than longer-chain fatty acids.(ABSTRACT TRUNCATED AT 400 WORDS)
-
In this review, we have considered interrelationships between blood flow and oxygen requirements of the body during fetal and neonatal development. During fetal life, blood is oxygenated in the placenta and returns to the fetus through the umbilical vein. The ductus venosus serves as a bypass of umbilical venous blood from the hepatic microcirculation. ⋯ In association with the increase in oxygen requirements after birth, cardiac output increases, but because resting requirements for blood flow are high, there is a limited ability for cardiac output to be increased further. With postnatal development, cardiac output requirements in relation to body weight decrease, partly in parallel with reduced oxygen requirements related to body weight, but also as a result of rightward shift of the oxygen dissociation curve as fetal hemoglobin is replaced by adult hemoglobin. Understanding the circulatory and metabolic changes that occur in the perinatal period and the mechanisms of response to stress is important in management of the newborn infant with cardiorespiratory distress.