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Biomedical subjects

V E Shih

Publications and source records attributed to V E Shih.

At least 91 records · Page 5Linked to original sources
PubMed1978

Ocular and biochemical abnormalities in gyrate atrophy of the choroid and retina.

Patients with gyrate atrophy of the choroid and retina have myopia, constricted visual fields, elevated dark adaptation thresholds, small or nondetectable ERGs, and chorioretinal atrophy. Biochemical abnormalities include hyperornithinemia, hypolysinemia, hyperornithinuria, an unknown amino compound in the urine, and virtual absence of OKT activity in extracts of cultured skin fibroblasts. Extracts of cultured skin fibroblasts from one patient studied in our laboratory showed an increase in OKT activity with increasing concentrations of vitamin B6 in the assay medium; this patient also showed some biochemical responsiveness within three weeks to 300 mg/day or orally administered vitamin B6. Three patients whose fibroblasts did not show increased OKT activity in vitro with increasing vitamin B6 did not respond in vivo to 300 mg/day of vitamin B6 over the same period. All four patients continue to be evaluated with larger doses of this vitamin. It remains to be established if long-term treatment with vitamin B6 will stabilize the course of the chorioretinal degeneration for at least some patients with this disease.

Administration, Oral↗
PubMed1978

Ornithine ketoacid transaminase deficiency in gyrate atrophy of the choroid and retina.

Gyrate atrophy of the choroid and retina is a chorioretinal degeneration associated with hyperornithinemia with an autosomal recessive mode of inheritance. Cultured skin fibroblasts from five affected patients showed a virtual absence of ornithine ketoacid transaminase (OKT) (L-ornithine:2-oxoacid aminotransferase E.C.2.6.1.13) activity. Fibroblasts from four carrier parents showed a 42%-65% reduction in OKT activity. Increasing the concentration of pyridoxal phosphate (vitamin B6 in the assay media resulted in partial restoration of OKT activity in fibroblasts from one out of five patients studied. We conclude that OKT deficiency is closely associated with the genetic defect in gyrate atrophy of the choroid and retina and that genetic heterogeneity exists in this disease.

Adolescent↗
PubMed1977

Sulfite oxidase deficiency. Biochemical and clinical investigations of a hereditary metabolic disorder in sulfur metabolism.

Study of a 4 1/2-year-old boy with the unusual combination of acute infantile hemiplegia, ectopia lentis and the absence of homocystinuria showed large amounts of abnormal sulfur-containing metabolites (sulfite, thiosulfate and S-sulfocysteine) in the urine. Sulfite and S-sulfocysteine were also present in the plasma. His inorganic sulfate excretion was only 50 per cent of total sulfur, as compared with 75 to 95 per cent by controls. Loading with L-cysteine hydrochloride and L-methionine further increased the excretion of sulfite and thiosulfate, but not inorganic sulfate excretion. Sulfite oxidase activity in skin fibroblasts average 1.07 nmol of cytochrome d reduced per milligram of protein per minute in control lines; it was not detectable (less than 5 per cent) in the patient. Activity was reduced in both parents (0.50 in the father and 0.32 in the mother)--compatible with autosomal recessive inheritance. Good biochemical responses to a low sulfur amino acid diet suggest that early treatment may benefit the patient.

Amino Acids, Sulfur↗
PubMed1976

Metabolism of [1-(14)C] and [2-(14)C] leucine in cultured skin fibroblasts from patients with isovaleric acidemia. Characterization of metabolic defects.

Leucine metabolism in cultured skin fibroblasts from patients with isovaleric acidemia was compared with that in normal fibroblasts and in cells from patients with maple syrup urine disease using [1-(14)C] and [2-(14)C] leucine as substrates. Inhibitory effects of methylenecyclopropylacetic acid on leucine metabolism in normal cells were also investigated. Production of 14CO2 from [2-(14)C] leucine was very reduced (96-99%) in both types of mutant cells. Radioactive isovaleric acid accumulated in assay media with isovaleric acidemia cells but not in those with maple syrup urine disease cells. Unexpectedly, 14CO2 production from [1-(14)C] leucine was partially depressed (80%) in isovaleric acidemia cells whereas in maple syrup urine disease cells it was strongly depressed (99%) as expected. These two mutant cells were clearly distinguished by detection of 14C-isovaleric acid accumulation after incubation with [2-(14)C] leucine. A pattern of inhibition of leucine oxidation similar to that seen in isovaleric acidemia cells was induced in normal cells by the addition of 0.7 mM methylenecyclopropylacetic acid to the assay medium. The partial inhibition of [1-(14)C] leucine oxidation seen in isovaleric acidemia cells and also in normal cells in the presence of the inhibitor appears to be, at least in part, due to an accumulation of isovalerate in the cells. Isovaleric acid (5-10) mM) inhibited [1-(14)C] leucine oxidation 32-68% when added to the assay medium with normal cells. Addition of flavin adenine dinucleoside to culture medium or assay medium or both did not restore oxidation of either leucine substrate in isovaleric acidemia cells.

2-Methyl-4-chlorophenoxyacetic Acid↗
PubMed1976

Type II hyperprolinemia. Delta1-pyrroline-5-carboxylic acid dehydrogenase deficiency in cultured skin fibroblasts and circulating lymphocytes.

Type II hyperprolinemia is an inherited abnormality in amino acid metabolism characterized by elevated plasma proline concentrations, iminoglycinuria, and the urinary excretion of delta1-pyrroline compounds. To define the enzymologic defect of this biochemical disorder, we developed a specific, sensitive radioisotopic assay for the proline degradative enzyme delta1-pyrroline-5-carboxylic acid dehydrogenase. Using this assay, we have shown an absence of delta1-pyrroline-5-carboxylic acid dehydrogenase activity in the cultured fibroblasts from three patients with type II hyperprolinemia. We confirmed this result on cultured cells by demonstrating a similar absence of delta1-pyrroline-5-carboxylic acid dehydrogenase activity in extracts prepared from the peripheral leukocytes of these patients. Additionally, we found significantly decreased levels of delta1-pyrroline-5-carboxylic acid dehydrogenase activity in the leukocyte extracts from five obligate heterozygotes for type II hyperprolinemia. We also demonstrated a reduction in leukocyte delta1-pyrroline-5-carboxylic acid dehydrogenase activity in three successive generations of a family. These results prove that an absence of delta1-pyrroline-5-carboxylic acid dehydrogenase is the enzymologic defect in type II hyperprolinemia and that this defect is inherited in an autosomal recessive fashion.

Amino Acid Metabolism, Inborn Errors↗
PubMed1976

Congenital hyperammonemic syndromes.

Urea cycle disorders and other hyperammonemic syndromes should be considered in the differential diagnosis in newborns with a history of severe vomiting, lethargy, and seizures, and in infants with feeding problems, episodic vomiting, and altered consciousness. Although the acute neonatal forms of urea cycle disorders are almost always lethal, several of the subacute forms of hyperammonemic syndromes respond favorably to early treatment.

Amino Acid Metabolism, Inborn Errors↗
PubMed1975

Hereditary pancreatitis. Nonspecificity of aminoaciduria and diagnosis of occult disease.

Hereditary pancreatitis appears in many different ways and in a variety of age groups, spanning both pediatric and adult medicine. The variable expression of hereditary pancreatitis is emphasized by the difficulty in diagnosing it in a patient obviously at risk because of a severely affected father and son. The morphine prostigmine test and hypotonic duodenogram were most helpful. Aminoaciduria previously associated with this disorder is coincidental or nonspecifically related to acute pancreatic inflammation. The increased risk for pancreatic carcinoma (about 20%) is emphasized by the concern for that complication in the proband's grandfather.

Adult↗
PubMed1974

Amino acid metabolism in acute renal failure: influence of intravenous essential L-amino acid hyperalimentation therapy.

A solution of 8 essential I-amino acids and hypertonic dextrose was administered to 5 patients in acute postoperative renal failure in a program of hyperalimentation designed to decrease the patient's catabolic state and to accrue certain metabolic benefits. A sixth patient receiving intravenous glucose alone served as a control. The pretreatment plasma concentrations of amino acids in all 6 patients did not differ significantly from normal; following intravenous essential amino acids at a dose of approximately 12.6 gm/24 hours, no significant elevations out of the normal range of these substances occurred. Since urinary excretion rates did not dramatically increase, urinary loss was excluded as a possible cause for the failure of increase of plasma concentrations. The results suggest that the administration of an intravenous solution of 1-amino acids and hypertonic dextrose is associated with rapid clearance from the blood of these substances and, with a failure of increased urinary excretion, indirect evidence of amino acid utilization for protein synthesis has been obtained. Histidine supplementation in patients with acute renal failure is probably unnecessary based on the lack of significant decreases in histidine concentrations in these patients.

Acute Kidney Injury↗