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Biomedical subjects

V E Shih

Publications and source records attributed to V E Shih.

At least 73 records · Page 4Linked to original sources
PubMed1982

Defective ornithine metabolism in cultured skin fibroblasts from patients with the syndrome of hyperornithinemia, hyperammonemia and homocitrullinuria.

The syndrome of hyperornithinemia, hyperammonemia, and homocitrullinuria (HHH) is a metabolic disorder resulting in protein intolerance and mental retardation. The primary metabolic defect has yet to be determined. We studied some aspects of ornithine metabolism in cultured skin fibroblasts from two patients from two patients with the HHH syndrome. The fibroblasts failed to incorporate 14C-label from ornithine into protein, a defect also observed in fibroblasts from patients with gyrate atrophy of the choroid and retina and a deficiency of ornithine aminotransferase activity. The defect can be corrected in heterokaryons formed between these two types of fibroblasts. These findings indicate that fibroblasts are suitable for further studying the underlying metabolic defect in HHH syndrome. The combination of the ornithine incorporation assay and genetic complementation analysis provide a confirmatory test for the diagnosis of this syndrome.

Amino Acid Metabolism, Inborn Errors↗
PubMed1982

D-lactic acidosis simulating a hypothalamic syndrome after bowel bypass.

A 36-year-old man had one year of periodic symptoms suggestive of episodic hypothalamic dysfunction: hypersomnia, thirst, ravenous hunger and gorging behavior, pallor, and irritability. However, neuroendocrine testing proved normal. A mild transient acidosis at the onset of his attacks and a history of bowel bypass five years earlier prompted metabolic screening. Markedly increased urinary D-lactic and phenolic acids were present, as were intermittent elevations of plasma D-lactic acid during two symptomatic episodes. Prompt and sustained clinical remission coincided with disappearance of abnormal organic acid excretion during oral antibiotic therapy. D-Lactic acidosis must be considered in the differential diagnosis of otherwise unexplained neurological syndromes, particularly in patients with altered bowel anatomy.

Acidosis↗
PubMed1982

A two year trial of low protein, low arginine diets or vitamin B6 for patients with gyrate atrophy.

Four patients with gyrate atrophy on low protein (20-35 g/day), low arginine diets and one on vitamin B6 (300 mgm/day) have maintained their plasma ornithine concentrations in the range of 30-60% of pre-therapeutic trial levels for about two years. After two years, three of the five patients have shown no significant change in Snellen visual acuity, visual fields, final dark-adapted thresholds or full-field electroretinograms. All five patients have shown slight enlargement of areas of chorioretinal atrophy in the midperiphery. These patients continue on low protein, low arginine diets or on vitamin B6 to determine whether any reduction in the hyperornithinemia will result in stabilization of retinal function.

Adolescent↗
PubMed1981

Variation in argininosuccinate synthetase activity in amniotic fluid cell cultures: implications for prenatal diagnosis of citrullinemia.

Argininosuccinate synthetase activity was measured in amniotic fluid cells cultured from 25 normal fetuses and from 2 fetuses at risk for citrullinemia. Among the 25 control lines, argininosuccinate synthetase was low in epithelial-like cultures and high in more fibroblast-like cultures. The radioactivity incorporated from 14C-citrulline into protein was proportional to argininosuccinate synthetase activity. The activity of argininosuccinate lyase, the next enzyme in the urea cycle, was unaffected by a predominance of one or the other cell type. Argininosuccinate synthetase was low but detectable in cells from the two fetuses at risk for citrullinemia. The pregnancies were continued and both resulted in clinically normal females. Thus factors such as predominant cell type may affect area cycle enzyme activity in cultured amniotic fluid cells and should be taken into consideration in attempts to diagnose citrullinemia prenatally.

Amino Acid Metabolism, Inborn Errors↗
PubMed1981

Reduction of hyperornithinemia with a low protein, low arginine diet and pyridoxine in patients with a deficiency of ornithine-ketoacid transaminase (OKT) activity and gyrate atrophy of the choroid and retina.

Five patients with gyrate atrophy of the choroid and retina showed a 60% of greater decline in plasma ornithine levels during a five week trial of a low protein (10--15 g/day), low arginine (0.50--0.75 g/day) diet supplemented with essential amino acids and pyridoxine administration. These declines in plasma ornithine levels were seen in Patients 1--4 with the pyridoxine non-responsive variant and in Patient 5 with the pyridoxine responsive variant. No harmful systemic side effects were noted. Patients 1--4 continued on a modified low protein (20--35 g/day), low arginine (1.25--1.75 g/day) diet as tolerated and Patient 5 on pyridoxine alone. After one year no improvement was observed in visual acuities, visual fields, final dark adapted thresholds and full field electroretinograms for four patients. In contrast to the other four patients, Patient 3, with relatively poor control of plasma ornithine levels, showed signs of progression of the chorioretinal atrophy and further reduction of electroretinographic responses. Patients 1--4 continue on the dietary regimen and Patient 5 on pyridoxine alone to determine whether any lowering of plasma ornithine levels will modify the course of their ocular disease.

Adolescent↗
PubMed1981

Ocular findings in patients with gyrate atrophy on pyridoxine and low-protein, low-arginine diets.

Five patients, ages 12 to 30, with gyrate atrophy have shown substantial (60% or greater) decreases in plasma ornithine concentrations within four to eight weeks when placed on a therapeutic trial of low-protein (10-15 g/day), low-arginine diets supplemented with essential amino acids (EAA) and pyridoxine hydrochloride. Four of five patients have continued on modified protein restriction (20-35 g/day) and one on pyridoxine (300 mg/day) alone with maintenance of plasma ornithine in the range of 30 to 60% below pretherapeutic trial levels. After one year, four of five patients have shown no significant improvement in visual acuity, fields, final dark-adapted thresholds, electroretinograms, or fundus appearance. One patient with the poorest control of plasma ornithine has developed a decrease in ERG amplitudes and a new area of chorioretinal atrophy. These patients continue in this trial to determine whether or not any reductions in hyperornithinemia will modify the course of the ocular disease.

Adolescent↗
PubMed1981

Massachusetts Metabolic Disorders Screening Program. II. Methylmalonic aciduria.

Screening neonates for methylmalonic aciduria is part of routine screening for metabolic disorders in Massachusetts. The process of urine collection by the parent and transmitted to the central screening laboratory was described in a previous publication (Pediatrics 49: 825, 1972). The primary objective of screening for methylmalonic aciduria is to detect methylmalonic acidemia, an inherited organic acid disorder. During the most recent 5 1/2-year period when the sensitive fast blue B stain was used in the analysis, four infants with methylmalonic acidemia were detected among 293,535 screened. Additional infants and children who came to attention because of clinical illness or family study also could be readily detected. Prior to this period, 325,634 neonates had been screened with the aniline-xylose method, which proved to be not sensitive enough for the identification of methylmalonic aciduria. Some affected infants have responded well to therapy and are clinically normal while two have shown poor biochemical response and are developmentally delayed. Four children in two families appear to have a benign variant of methylmalonic acidemia. Based on these studies the observed incidence of methylmalonic acidemia in Massachusetts is 1:48,000. Screening for methylmalonic aciduria may be an appropriate addition to newborn screening programs.

Child↗
PubMed1980

Glutaric acidemia: a metabolic disorder causing progressive choreoathetosis.

A boy with glutaric acidemia had psychomotor retardation first noted at age 6 months, recurrent metabolic acidosis, and a progressive quadriparesis with choreoathetosis. He died at age 3 1/2 years. Cultured skin fibroblasts lacked glutaryl-CoA dehydrogenase activity. There was a biochemical, but not a clinical, response to dietary restriction of lysine and tryptophan. The caudate and putamen of the brain showed severe loss of nerve cells and fibers with proliferation of astrocytes, as well as markedly reduced gamma-aminobutyric acid and glutamate decarboxylase activity.

Acidosis↗
PubMed1978

Plasma and urine amino acid changes in rats treated with hypoglycin.

Hypoglycin A is a toxin which causes Jamaican vomiting sickness. In rats treated with this compound, we observed significant increases in a number of amino acids in the plasma and the urine, and detected several unidentified amino compounds in the urine. These changes suggest that hypoglycin, in addition to its known inhibitory effect on acyl-CoA dehydrogenases interferes with some steps in nitrogen metabolism as well. The amino acid abnormalities seen in hypoglycin-treated rats are compared with those seen in Reye's syndrome.

Amino Acids↗
PubMed1978

Galactose-1-phosphate uridyl transferase deficiency due to Duarte/galactosemia combined variation: clinical and biochemical studies.

The most common abnormality detected by the screening of newborn infants for galactosemia is a deficiency of galactose-1-phosphate uridyl transferase due to the presence in one individual of allelic genes for the Duarte variant and for galactosemia. Clinical studies of ten untreated individuals with this genetic compound, including three adults, failed to reveal evidence of cataracts, liver disease, or mental subnormality, the major clinical complications associated with galactosemia. Galactose-1-phosphate was not detectable in umbilical cord blood from one infant. Galactose was not detectable in random blood specimens from any of the individuals and was present in only small amounts following ingestion of milk in one infant and a child. It would appear that this common gentic variation is usually, if not always, benign.

Adult↗