The clinical, laboratory, and pathologic findings in a patient with a previously undescribed deficiency in fatty acid oxidation are summarized. The patient had a fatal defect in fatty acid metabolism profoundly affecting heart, skeletal muscle, liver, and kidney. Oxidation of palmitate was 38-51% of controls. Complementation assays demonstrated that the patient's fibroblasts complemented fibroblast lines from all known defects in fatty acid oxidation except long-chain acyl-CoA dehydrogenase deficiency. Urine and serum carnitine profiles also were indicative of a defect in the oxidation of long-chain substrate; however, the palmitoyl-CoA dehydrogenase activity was actually increased. This finding indicates that the patient had a defect that was distinct from, but possibly related to, long-chain acyl-CoA dehydrogenase deficiency. This patient demonstrates the laboratory and pathologic findings in defects in fatty acid oxidation and how they differ from those in Reye syndrome.

Acyl-CoA Dehydrogenase, Long-Chain↗

PubMedDate not supplied

Formation of a novel arachidonic acid metabolite in peroxisomes.

A new radiolabeled metabolite was released into the extracellular fluid by normal human skin fibroblasts that were labeled with [5,6,8,9,11,12,14,15-3H] arachidonic acid. This product continued to accumulate during a 24 h incubation, and its formation was not saturated at arachidonic acid concentrations up to 15 mumol/L. The compound, identified as hexadecatrienoic acid, was not produced by Zellweger fibroblasts which are deficient in peroxisomal fatty acid beta-oxidation. By contrast, radiolabeled hexadecatrienoic acid was produced by mutant fibroblasts having other peroxisomal defects, including X-linked adrenoleukodystrophy, adult Refsum's disease, and rhizomelic chondrodysplasia punctata. This radiolabeled metabolite also was produced by mutant fibroblasts that cannot oxidize long-chain fatty acids in the mitochondria. These results indicate that hexadecatrienoic acid is synthesized from arachidonic acid by peroxisomal beta-oxidation. The absence of this pathway may account for some of the biochemical and functional abnormalities that occur in Zellweger's syndrome.

Adrenoleukodystrophy↗

PubMedDate not supplied

Sudden infant death syndrome: plasma vitamin E levels and dietary factors.

Vitamin E and selenium deficiency have previously been suggested to be responsible for the Sudden Infant Death Syndrome (SIDS). New experimental data reveal that this is not the case since vitamin E as well as plasma selenium levels of SID infants are approximately equal to those of normal controls. Although breast feeding was believed to have a protective effect against SIDS, a statistical study of groups of SID- and control infants in San Diego County indicate no such correlation. Totally or partially breast-fed SID infants actually died at an earlier age than those fed by formula only (p=0.02). Compared to matched normal controls, SID infants appear to have received a less varied diet with a lower incidence of extradietary vitamin supplementation (p=0.02). There is also a somewhat greater prevalence of mothers smoking during pregnancy in the SID group (one-tail p=0.05).

Autopsy↗