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Biomedical subjects

W G Ng

Publications and source records attributed to W G Ng.

At least 37 records · Page 2Linked to original sources
PubMed1988

Lysosomal enzyme activities among Chinese: leukocyte alpha-galactosidase and beta-galactosidase.

alpha-Galactosidase and beta-galactosidase activities have been determined in leukocyte preparations from 100 randomly selected Chinese adults. For alpha-galactosidase, two groups with low activities were identified: group I consisted of 3 females having activities below 40% of normal, and group II consisted of 5 males and 1 female with activities about 60% of normal. Family studies suggested that these low alpha-galactosidase activities are genetically determined. Only 1 individual was found to have about 50% of normal beta-galactosidase activity; presumably he is a carrier for beta-galactosidase deficiency (GM1 gangliosidosis).

Adult↗
PubMed1987

Müllerian aplasia associated with maternal deficiency of galactose-1-phosphate uridyl transferase.

The activity and electrophoretic pattern of galactose-1-phosphate uridyl transferase (transferase), a key enzyme in galactose metabolism, were analyzed in four patients with Müllerian aplasia (Rokitansky-Küster-Hauser syndrome) and their mothers. Mothers of two of the patients had genetic variations of their transferase enzymes with activities below the normal range. Affected daughters from these two mothers also had genetic variations of the transferase enzyme. In one of the patients whose Müllerian aplasia had been diagnosed 15 years previously, premature ovarian failure developed. These case reports suggest a possible association between errors of galactose metabolism, Müllerian aplasia, and premature menopause--an association that is supported by a rodent model in which female offspring of mothers fed a high-galactose diet were born with reduced oocyte numbers and delayed vaginal opening.

Adult↗
PubMed1986

Pyruvate carboxylase defect: metabolic studies on cultured skin fibroblasts.

Oxidative studies using a number of radioactive carbon-labelled substrates on intact cultured skin fibroblasts from a patient with pyruvate carboxylase deficiency revealed dysfunction of the Krebs cycle. The suppression of CO2 production from aspartate but not glutamine strongly suggests that the defective function lies in the aspartate-malate shuttle. Furthermore, there is an unusual dependence on glutamine for the maintenance of growth of the patient's cells compared to normal cells. Glutamine could not be replaced by aspartate supplementation. A secondary defect resulting in accumulation of lipid material was also demonstrated in this study. It is speculated that the intracellular level of oxaloacetate may also be diminished in the patient's cells. Oxaloacetate is primarily generated by the carboxylation of pyruvate catalysed by pyruvate carboxylase.

Acetyl Coenzyme A↗
PubMed1986

Methylmalonic and propionic acidemias: lipid profiles of normal and affected human skin fibroblasts incubated with [1-14C]propionate.

Normal human skin fibroblasts and those from methylmalonic acidemia and propionic acidemia patients were grown in culture. Following incubation with [1-14C]propionate, the major lipid classes in the cells were separated by thin layer chromatography and isolated fractions analyzed by radio gas chromatography for the presence of odd-numbered long-chain fatty acids; the pattern of even-numbered long-chain fatty acids was obtained also. Normal fibroblasts incorporated a small percentage of propionate into odd-numbered fatty acids which were present in all lipids studied. The abnormal cells incorporated a larger amount while maintaining the characteristic ratios of odd-numbered fatty acids found in the normal line. Most of the radioactivity was associated with phospholipids which are the predominant constituents of cell membranes. A characteristic C15/C17 ratio was found for different phospholipids and the triglyceride fraction; pentadecanoic acid was the principal odd-numbered fatty acid utilized in the assembly of complex lipids. Compared to even-numbered long-chain fatty acids the absolute amount of odd-numbered fatty acids was low (1-2%), even in affected cells. An unusual polar lipid fraction was isolated in the course of the study. In the normal cell it contained several unlabeled eicosanoids which were missing from the same fraction of both affected cell lines.

Amino Acid Metabolism, Inborn Errors↗
PubMed1985

Beta-glucuronidase deficiency. A heterogeneous mucopolysaccharidosis.

We studied two cases of beta-glucuronidase deficiency. One patient's disease was present at birth and the other patient's disease appeared in early childhood. The symptoms observed in both patients, although of differing severity, included peculiar facies, cloudy cornea, hepatosplenomegaly, hernia, kyphosis, recurrent infections, short stature, and developmental delay, as well as increased excretion of urinary chondroitin sulfate A/C and decreased levels of beta-glucuronidase activity. We reviewed all of the reported cases and examined the biochemical and clinical heterogeneity observed in this disorder.

Child↗
PubMed1985

False-positive amniotic fluid acetylcholinesterase results: the need for a multifacet approach to the prenatal diagnosis of neural tube defects.

Two cases are presented with false-positive amniotic fluid alpha-fetoprotein and acetylcholinesterase results for the prenatal diagnosis of neural tube defects. Stage II ultrasound revealed no lesions of the fetal spine in both cases. The alpha-fetoprotein and acetylcholinesterase results returned to normal on subsequent taps. Both pregnancies resulted in normal outcomes. A protocol is presented for managing pregnancies with abnormal alpha-fetoprotein and acetylcholinesterase results.

Acetylcholinesterase↗
PubMed1984

Partial ornithine transcarbamylase deficiency associated with recurrent hyperammonemia, lethargy and depressed sensorium.

A 6-year-old boy presented with recurrent coma associated with hyperammonemia and infection is reported. A liver biopsy revealed decreased ornithine transcarbamylase (OTC) activity (16% of normal). The enzymatic abnormality in the child is supported by the finding of elevated orotic acid excretion in his mother following a protein load, compatible with an X-linked pattern of inheritance. Since initiation of a dietary arginine supplement, the child has not had recurrent episodes of hyperammonemia.

Amino Acid Metabolism, Inborn Errors↗
PubMed1983

Prenatal diagnosis of pseudo arylsulphatase A deficiency.

Prenatal diagnosis was performed on a pregnancy at risk for metachromatic leukodystrophy (MLD) in a family with the pseudo arylsulphatase A deficiency trait. Extracts of cultured amniotic fluid cells were deficient in arylsulphatase A indicating that the fetus was either affected with MLD or had the benign pseudodeficiency trait. In the cerebroside sulphate loading test, the at risk cells hydrolysed sulphatide like control cultured amniotic fluid cells implying that the fetus had pseudodeficiency. The pregnancy was carried to term and a male child was delivered. Placenta, urine and fibroblasts had very low activities of arysulphatase A. However, no sulphatide could be detected in urine and growing fibroblasts responded normally in the cerebroside sulphate loading test, suggesting pseudodeficiency. At 29 months, the infant is healthy and shows no stigmata of MLD. The prediction based on the results of the cerebroside sulphate loading test on cultured amniotic fluid cells appeared to be borne out.

Amniotic Fluid↗
PubMed1983

Neonatal pyruvate carboxylase deficiency with renal tubular acidosis and cystinuria.

This report concerns a patient with severe congenital lacticacidosis associated with proximal renal tubular acidosis and cystinuria. Enzyme studies with cultured skin fibroblasts obtained from the patient revealed zero pyruvate carboxylase activity, but propionyl-CoA carboxylase activity was normal. Administration of various vitamins in large amounts did not improve the clinical condition. In contrast, the patient began to thrive when her diet was supplemented with aspartic acid, asparagine, glutamic acid, and glutamine. The particular dietary treatment used and the biochemical findings merit consideration for management of future cases.

Acidosis↗
PubMed1982

Presymptomatic diagnosis: metachromatic leukodystrophy or pseudo arylsulphatase A deficiency?

Diagnosis of metachromatic leukodystrophy (MLD) was established in the proband at age 27 months. An examination of the family arylsulphatase A profile revealed that the father and younger sibling, age 2 months, had very low enzyme activities like the proband. The father, in all likelihood, had the pseudo arylsulphatase A deficiency trait, but the sibling could be either pseudodeficient or affected with MLD. The fibroblast cerebroside sulphate loading test confirmed that the father had pseudo arylsulphatase A deficiency. The test also indicated that the sibling was affected with MLD. This was confirmed by clinical evidence of neurological degeneration by 18 months.

Cerebroside-Sulfatase↗