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T L Oei

Publications and source records attributed to T L Oei.

At least 19 recordsLinked to original sources
PubMed1988

Myoadenylate deaminase deficiency: a clinical, genetic, and biochemical study in nine families.

The clinical significance of myoadenylate deaminase (MAD) deficiency and its mode of inheritance is still questioned. There were 36 relatives of 9 unrelated MAD deficient patients who were examined with the aid of a standardized ischemic forearm test: 8 new cases of MAD deficiency were detected, 5 of which were confirmed histochemically and biochemically. Obligate heterozygotes showed a normal ammonia production and MAD staining, but the mean activity of the enzyme was significantly less than in a group of controls. The results obtained from the family study strongly suggest an autosomal recessive mode of inheritance. However, only 2 of the 8 newly found MAD deficient individuals complained of exertional myalgia, whereas the remaining 6 were without any symptoms or complaints. This finding casts doubt on the clinical significance of MAD deficiency and the relationship of the deficiency state with exertional myalgia.

AMP Deaminase↗
PubMed1988

The gene for X-linked progressive mixed deafness with perilymphatic gusher during stapes surgery (DFN3) is linked to PGK.

A linkage analysis has been performed in a large Dutch kindred with progressive mixed deafness with perilymphatic gusher during stapes surgery (DFN3) using a panel of X-chromosomal RFLPs. Tight linkage (zmax = 3.07 at 0 = theta = 0.00) was demonstrated with the locus for phosphoglycerate kinase (PGK), which is located at Xq13. Tight linkage was excluded for DXS9 (probe RC8) and DXS41 (probe 99.6) on Xp and for blood clotting factor 9 (FIX) on distal Xq. Deafness is one of the predominant clinical features in males with deletions of the Xq21 band. Our results suggest that this association may be due to involvement of the DFN3 gene.

DNA Probes↗
PubMed1987

AMP deaminase deficiency: study of the human skeletal muscle purine metabolism during ischaemic isometric exercise.

Muscle biopsies were taken from 10 control subjects and five AMP deaminase (AMPD) deficient individuals before and after an ischaemic isometric exercise test and analysed for purine nucleotide, NAD+, creatine phosphate (CP) and lactate content. The decrease of ATP induced by the exercise test was significantly lower in the AMPD deficient patients than in the controls, but the decrease of creatine phosphate and the increase of lactate did not differ. There were no significant differences in the exertional performance level between patients and controls and no evidence was obtained of an increased energy expenditure per unit of performance in AMPD deficiency. The AMPD deficient individuals were equally capable of maintaining a high adenylate energy charge (EC) as the control subjects, which indicates a normal regulation of the balance between ATP consumption and ATP regeneration. ATP, ADP and total adenine nucleotide (TAN) but not AMP, were significantly elevated in the AMPD deficient patients as compared with the controls before as well as after the exercise test. This underlines the role of AMPD activity in the adenine nucleotide catabolism of skeletal muscle.

AMP Deaminase↗
PubMed1986

Ischaemic exercise test in myoadenylate deaminase deficiency and McArdle's disease: measurement of plasma adenosine, inosine and hypoxanthine.

Plasma adenosine, inosine and hypoxanthine concentrations were assayed in seven control subjects, five myoadenylate deaminase deficient (MADD) patients and six McArdle patients before and after ischaemic forearm exercise. The plasma adenosine increase was very low in all test groups and there were no significant differences. The MADD patients showed a significantly lower increase of plasma inosine and hypoxanthine after exercise as compared with the controls. In the McArdle patients the increase in plasma inosine and hypoxanthine after exercise did not differ significantly from the values measured in the controls. The ischaemic exercise test with measurement of plasma inosine and hypoxanthine might be of diagnostic value in MADD, but not in McArdle's disease.

AMP Deaminase↗
PubMed1983

The influence of bilirubin, alcohol and certain drugs on the kinetics of 99mTc-Diethyl IDA (EHIDA) in humans.

On the basis of the mathematical analysis of 99mTc-EHIDA hepatobiliary time-activity curves of normal individuals two rate constants, one related to accumulation of radioactivity (uptake) and the other to excretion, were calculated indicating a two-compartmental model. By means of computerized fitting the rate constant of excretion (Kb), the time of maximum uptake (Tmax) and the rate constant of uptake (Ka) were calculated. In severely jaundiced patients (serum bilirubin concentrations greater than 140 mumol/l) a markedly decreased or absent uptake of 99mTc-EHIDA was observed. In moderately jaundiced patients a low Kb was invariably observed; in obstructive jaundice due to malignant disease--but not in jaundice of benign obstructive or hepatocellular origin--an increase in Ka was frequently present. This latter finding was not always present, however, and consequently kinetic studies do not unequivocally differentiate between jaundice of obstructive and hepatocellular origin. A markedly increased uptake (a high Ka) was noticed in alcoholics and patients taking phenobarbital and diphenylhydantoin possibly because of drug-induced membrane alterations. When the alcoholics developed hepatocellular injury the Ka converted to normal values. Thus, 99mTc-EHIDA kinetics may be useful in the follow-up of patients with established or suspected alcoholism by virtue of the fact that it appears to be a sensitive monitor of functional changes in hepatocyte plasma membrane properties.

Alcoholism↗
PubMed1979

Heterozygote detection in glucose-6-phosphate dehydrogenase deficiency: limitation of hair follicle analysis.

Glucose-6-phosphate dehydrogenase deficiency was demonstrated in a case of favism. The X-linked enzyme defect was expressed in erythrocytes but not in hair root cells. Predictably, the mother shown to be a heterozygous carrier on the basis of intermediate erythrocyte glucose-6-phosphate dehydrogenase activity could not be identified as a carrier by means of hair root study. It seems to be necessary to test the hair roots of at least one enzyme-deficient member of the family to exclude false negative results, if hair root analysis is used for carrier detection. Because of the more or less clonal origin of hair roots, they remain a convenient biopsy material with which to study heterozygosity in X-linked inborn errors of metabolism.

Child↗
PubMed1979

Glucose-6-phosphate dehydrogenase deficiency: biochemical and histochemical studies on hair roots for carrier detection.

Kinetic properties of human hair root glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were studied in order to optimize the assay of these enzymes in lysates from single hair roots. In contrast to previously reported methods, an excess of purified 6-phosphogluconate dehydrogenase was added to the glucose-6-phosphate dehydrogenase reaction mixtures, thus allowing a more exact quantification of glucose-6-phosphate dehydrogenase activity. Although enzyme histochemical techniques suggest a similar distribution of hair root glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, enzyme assays on hair root segments after microdissection nevertheless indicate differences in the distribution of these enzymes. Upon storage a gradual drop in the activity of both hair root enzymes was found, but the rate of decrease in enzyme activity was about equal: the enzyme activity ratio was, therefore, not affected. This opens interesting possibilities for mailing hair roots for screening purposes without any special precautions.

Genetic Carrier Screening↗
PubMed1978

Molecular and tissue-specific heterogeneity in HPRT deficiency.

In several patients with different degrees of HPRT deficiencies, residual activities have been determined in both lysed and intact erythrocytes. No close correlation could be found between the degree of HPRT deficiency and the severity of the clinical expression. Unless HPRT activity in both intact and lysed erythrocytes was below detection level, the residual activity in intact red blood cells was higher than in lysates. Tissue-specific heterogeneity was illustrated with a patient suffering from X-linked gout. Lysates from erythrocytes, leukocytes, and cultured fibroblasts showed 1%, 8%, and 100% of normal HPRT activity, respectively. Characterization of the erythrocyte and fibroblast HPRT from this patient showed no kinetic abnormalities. However, there was a decreased heat stability. It is concluded that for a better understanding of the pathophysiology in HPRT deficiency studies on nucleated cells from the different tissues are needed.

Erythrocytes↗
PubMed1978

Fabry's disease: biochemical and histochemical studies on hair roots for carrier detection.

A method of assay alpha-galactosidase and acid phosphatase activities in single hair roots is described. Enzyme histochemical studies show that the distribution of acid phosphatase in the human hair root matches that of alpha-galactosidase. Histochemically, the main activity is located in the upper part of the sheath near the orifice of the duct of the sebaceous gland. This is confirmed by enzyme assays on different parts of the hair root after dissection. The variation in the values found in individual hair roots is improved by relating alpha-galactosidase to acid phosphatase activities. Storage experiments indicate a remarkable stability of both alpha-galactosidase and acid phosphatase in human hair roots.

Acid Phosphatase↗
PubMed1978

An unusual form of galactosemia: studies on erythrocytes and hair roots.

An unusual form of galactosemia is described in a 7-month-old boy, characterized by a late onset of the clinical symptoms. A high apparent residual activity of erythrocyte galactose-1-phosphate uridyl transferase (GT) was measured with the spectrophotometric UDP-Glucose consumption test(+/-25% of normal). The residual activity in erythrocyte lysates, determined when the patient was 7, 16 and 22 months old, significantly decreased upon storage and after preincubation with NAD-ase. The radiochemical measurement of GT activity demonstrated a severe deficiency: only a level of +/-1% of normal activity was observed, and no effects of storage or NAD-ase could be demonstrated. GT and galactokinase (GK) activities were measured radiochemically in lysates from hair roots obtained from the human scalp, and it was found that the GT/GK activity ratio is a useful index for the detection of heterozygotes. Erythrocyte and hair root lysates from the heterozygous parents of the patient displayed GT/GK ratios which were intermediate between mutant and normal. Because they offer a simple and fast way to obtain biopsy material, hair roots might become of increasing importance for carrier detection studies.

Adult↗
PubMed1978

Characterisation of purine nucleoside phosphorylase from fibroblasts using ultra-microchemical methods.

A new technique to quantitate nucleoside phosphorylase (NP) activity in single or small numbers of counted visually selected cells is presented. Fibroblasts were cultivated on the plastic film bottom of culture dishes. After lyophilisation in situ, plastic film leaflets carrying a counted number of cells were cut out and tested for NP activity. Some properties of NP, including temperature stability, pH optimum and substrate affinity, have been studied. The data obtained suggest that Np might play a regulatory role in the purine interconversion pathway.

Fibroblasts↗
PubMed1978

A simple and sensitive radiochemical assay for plasma guanase.

A simple and sensitive radiochemical micro-assay has been developed for the determination of plasma guanase activity. The method is based upon the measurement of the conversion of 14C-labeled guanine to xanthine, catalysed by the enzyme guanase (guanine aminohydrolase;EC 3.5.4.3). Using this method, the catalytic activity in the plasma of adult healthy controls was 0.040 +/- 0.09 nmol/h.mg protein (x +/- s). In children under 5 years of age higher levels of enzyme activity were demonstrated. In adult patients with liver disease plasma guanase activities were found to be 3 to 7-fold increased as compared to the normal adult mean value.

Adolescent↗