Changes in blood carnitine and acylcarnitine profiles of very long-chain acyl-CoA dehydrogenase-deficient mice subjected to stress.

BACKGROUND: In humans with deficiency of the very long-chain acyl-CoA dehydrogenase (VLCAD), C14-C18 acylcarnitines accumulate. In this paper we have used the VLCAD knockout mouse as a model to study changes in blood carnitine and acylcarnitine profiles under stress. DESIGN: VLCAD knockout mice exhibit stress-induced hypoglycaemia and skeletal myopathy; symptoms resembling human VLCADD. To study the extent of biochemical derangement in response to different stressors, we determined blood carnitine and acylcarnitine profiles after exercise on a treadmill, fasting, or exposure to cold. RESULTS: Even in a nonstressed, well-fed state, knockout mice presented twofold higher C14-C18 acylcarnitines and a lower free carnitine of 72% as compared to wild-type littermates. After 1 h of intense exercise, the C14-C18 acylcarnitines in blood significantly increased, but free carnitine remained unchanged. After 8 h of fasting at 4 degrees C, the long-chain acylcarnitines were elevated 5-fold in knockout mice in comparison with concentrations in unstressed wild-type mice (P < 0.05), and four out of 12 knockout mice died. Free carnitine decreased to 44% as compared with unstressed wild-type mice. An increase in C14-C18 acylcarnitines and a decrease of free carnitine were also observed in fasted heterozygous and wild-type mice. CONCLUSIONS: Long-chain acylcarnitines in blood increase in knockout mice in response to different stressors and concentrations correlate with the clinical condition. A decrease in blood free carnitine in response to severe stress is observed in knockout mice but also in wild-type littermates. Monitoring blood acylcarnitine profiles in response to different stressors may allow systematic analysis of therapeutic interventions in VLCAD knockout mice.

Scimitar syndrome presenting in infancy.

BACKGROUND: Scimitar syndrome has a variable presentation based on the age at which the diagnosis is made. In general, infants presenting in heart failure have a greater number of associated anomalies and their prognosis is much worse. METHODS: We reviewed the records of all patients under our care at St. Louis Children's Hospital who presented with symptoms attributable to scimitar syndrome during their infancy. Twelve patients were identified. The average age at presentation was 6 weeks. RESULTS: The most common symptom at presentation was tachypnea. The chest roentgenogram demonstrated dextroposition of the heart and hypoplastic right lung. Only 1 patient had the classic "scimitar sign." Cardiac catheterization demonstrated pulmonary hypertension (pulmonary artery systolic pressure, 73.9+/-21.8 mm Hg). The Qp:Qs was 3.1+/-1.5:1. Two patients with severe associated anomalies were treated medically and both died. Two patients underwent occlusion of the systemic collaterals; one died and the other ultimately underwent complete repair due to persistence of the symptoms of heart failure. Two patients had primary right pneumonectomy and both are alive and well. Seven patients underwent complete repair (one after coil occlusion of the systemic arterial collaterals) and one died; three subsequently developed occlusion of the baffle from the orifice of the anomalous pulmonary vein and required pneumonectomy. Two patients required lung transplantation due to persistent pulmonary hypertension in one and recurrent bilateral pulmonary venous stenosis in the other. CONCLUSIONS: Infants presenting with scimitar syndrome generally have symptoms of tachypnea and chest roentgenograms showing dextrocardia and hypoplastic right lung. Although repair of the anomalous venous return and ligation of collaterals is generally recommended, right pneumonectomy (either as primary therapy or if repair failed) had similar early and late results.