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Biomedical subjects

C E Mize

Publications and source records attributed to C E Mize.

At least 37 records · Page 2Linked to original sources
PubMed1976

The occurrence of hepatoma in the chronic form of hereditary tyrosinemia.

A 5 1/2-year-old child with hepatocarcinoma complicating hereditary tyrosinemia is presented. A review of the literature and an attempted follow-up of previously reported patients with the chronic form of hereditary tyrosinemia have disclosed 16 cases of hepatocarcinoma occurring in 43 patients surviving beyond 2 years of age (37%). This incidence is considerably higher than that generally given for the occurrence of hepatoma in adults with macronodular cirrhosis. Females and males are equally at risk. Additional factors beyond the development of cirrhosis are likely operative in the induction of hepatocarcinoma in patients with this metabolic disorder; those surviving beyond infancy are at considerable risk for the development of fatal hepatic neoplasms.

Amino Acid Metabolism, Inborn Errors↗
PubMed1969

Localization of the oxidative defect in phytanic acid degradation in patients with Refsum's disease.

The rate of oxidation of phytanic acid-U-(14)C to (14)CO(2) in three patients with Refsum's disease was less than 5% of that found in normal volunteers. In contrast, the rate of oxidation of alpha-hydroxyphytanic acid-U-(14)C and of pristanic acid-U-(14)C to (14)CO(2), studied in two patients, while somewhat less than that in normal controls, was not grossly impaired. These studies support the conclusion that the defect in phytanic acid oxidation in Refsum's disease is located in the first step of phytanic acid degradation, that is, in the alpha oxidation step leading to formation of alpha-hydroxyphytanic acid. The initial rate of disappearance of plasma free fatty acid radioactivity after intravenous injection of phytanic acid-U-(14)C (t(1/2) = 5.9 min) was slower than that seen with pristanic acid-U-(14)C (t(1/2) = 2.7 min) or palmitic acid-1-(14)C (t(1/2) = 2.5 min). There were no differences between patients and normal controls in these initial rates of free fatty acid disappearance for any of the three substrates tested. There was no detectable lipid radioactivity found in the plasma 7 days after the injection of palmitic acid-1-(14)C or pristanic acid-U-(14)C in either patients or controls. After injection of phytanic acid-U-(14)C, however, the two patients showed only a very slow decline in plasma lipid radioactivity (estimated t(1/2) = 35 days), in contrast to the normals who had no detectable radioactivity after 2 days. Incorporation of radioactivity from phytanic acid-U-(14)C into the major lipid ester classes of plasma was studied in one of the patients; triglycerides accounted for by far the largest fraction of the total present between 1 and 4 hr.

Carbon Dioxide↗
PubMed1967

Refsum's disease: nature of the enzyme defect.

Two siblings with Refsum's disease, an inherited disorder of lipid metabolism, oxidized intravenously injected uniformly labeled phytanic acid-C(14) at rates less than 5 percent of those found in normal subjects. The defect in oxidation of phytanic acid persisted in cultures of fibroblasts from the patients' skin. The rate of oxidation of the phytanic acid-C(14) was less than 1 percent of that found in cultures of fibroblasts from normal skin. However, pristanic acid, previously shown to be the first product of phytanic acid degradation, was oxidized at a normal rate in the patients' cultures. These results indicate that the enzymatic defect in Refsum's disease is in the first step of the pathway for degradation of phytanic acid, that is, in the unusual alpha-oxidative process that leads to a shortening of phytanic acid by one carbon atom.

Carbon Dioxide↗
PubMed1967

Studies on the metabolic error in Refsum's disease.

Studies utilizing mevalonic acid-2-(14)C and D(2)O as precursors failed to provide evidence for an appreciable rate of endogenous biosynthesis of phytanic acid in a patient with Refsum's disease. Orally administered tracer doses of phytol-U-(14)C were well absorbed both by seven normal control subjects (61 to 94%) and by two patients with Refsum's disease (74 and 80%). The fraction of the absorbed dose converted to (14)CO(2) in 12 hours was 3.5 and 5.8% in Refsum's disease patients and averaged 20.9% in seven control subjects. Labeled phytanic acid was demonstrated in the plasma of both control subjects and patients given phytol-U-(14)C, establishing phytol in the diet as a potential precursor of phytanic acid. This labeled phytanic acid had disappeared almost completely from the plasma of the seven control subjects by 24 to 48 hours, whereas it persisted at high concentrations in the plasma of the two patients for many days. We conclude that the phytanic acid accumulating in Refsum's disease is primarily of exogenous origin and that patients with Refsum's disease have a relative block in the degradation of phytanic acid and possibly other similar branched-chain compounds. This may relate to a deficiency in mechanisms for release of phytanic acid from stored ester forms or, more probably, to reactions essential to oxidative degradation of the carbon skeleton.

Adult↗