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Biomedical subjects

S L Ch'ng

Publications and source records attributed to S L Ch'ng.

At least 19 recordsLinked to original sources
PubMed1994

A case of alkaptonuria with root canal stenosis.

Spinal involvement in alkaptonuria is common. Patients usually present in the third or fourth decade with spondylosis or acute intervertebral disc prolapse. Alkaptonuria with root canal stenosis has however hitherto not been reported. We wish to report one such patient.

Adult↗
PubMed1991

Drug interaction between cyclosporine A and quinine in a renal transplant patient with malaria.

We report a previously undocumented drug interaction between cyclosporine A and quinine. A 39 year old Asian with a recent renal transplant was diagnosed to have a mild cerebral falciparum malaria. He was treated with seven days of oral quinine (600 mg, 8 hourly), followed by a stat dose of pyrimethamine (75 mg)--sulfadoxime (1200mg) because of a strong suspicion of chloroquine resistant falciparum malaria. Using a polyclonal radioimmunoassay method, we measured morning trough cyclosporine A level before, during and after the quinine treatment. Results showed a gradual decrease in the cyclosporine A level from a baseline value of 328 ng/ml to 107 ng/ml after seven days of oral quinine with a subsequent rise to pre-treatment level after discontinuation of quinine. There was no significant change in the dose of cyclosporine A administered during the period of quinine treatment (4.05 to 3.83 mg/kg body weight). Biochemical liver function tests, serum creatinine and hematological parameters were also essentially unchanged during this period. In vitro study showed no significant methodological interference in the cyclosporine assay by quinine dihydrochloride. These findings suggest an in vivo drug interaction between cyclosporine A and quinine. The mechanism of this interaction is not clear. Further studies are required to confirm the significance of this observation. Quinine and its stereoisomer, quinidine should be used with caution until further information is available.

Adult↗
PubMed1990

Effects of fasting during Ramadan on urinary excretion in Malaysian Muslims.

Urine analysis was conducted on male Muslims before, during and after Ramadan. Various changes in urine volume, osmolality, total solute, sodium, potassium, titratable acidity and urea in response to altered feeding and activity regimens were found. There were no detectable levels of ketones, protein, glucose, urobilinogen and haemoglobin. It was concluded that the body adapted to fasting during Ramadan and that there were no adverse effects on renal function.

Acids↗
PubMed1990

Ventilatory function in Malay Muslims during normal activity and the Ramadan fast.

Pulmonary function parameters were examined in a Malay Muslim population during normal activity and Ramadan fasting conditions. The validity of employing various lung function prediction formulae for the subjects was also assessed. Present findings indicate that the water deprivation regime and resultant dehydration during Ramadan did not cause significant changes in ventilatory functions. Although pulmonary prediction formulae based on Caucasian and African populations were inapplicable to the subjects examined, the equations derived from the neighbouring populations in Singapore could be employed.

Adult↗
PubMed1989

Digoxin toxicity: clinical and laboratory assessment.

A prospective study to correlate clinical digoxin toxicity with serum digoxin levels was carried out in 67 patients of whom 24 were clinically toxic and 43 were asymptomatic. The patients were clinically diagnosed to be toxic based on typical cardiac arrhythmias (n = 11) or non-cardiac symptoms (n = 13). Blood samples were collected at least six hours after the last digoxin dose and the sera assayed for digoxin using a radioimmunoassay method. The mean serum digoxin level in the toxic group (x1 = 2.09 +/- 1.28 ng/ml) was significantly higher than in the non-toxic group (x2 = 1.20 +/- 0.75 ng/ml), p less than 0.01. All the non-toxic patients had serum digoxin levels below 3 ng/ml. However, there was a considerable overlap of serum digoxin levels between the two groups of patients. Serum level cannot be the sole criterion in diagnosing digoxin toxicity. Nevertheless, raised serum digoxin levels especially above 3 ng/ml, in the presence of suggestive clinical features is strongly suggestive of toxicity.

Adolescent↗
PubMed1989

Effect of altered eating pattern on serum fructosamine: total protein ratio and plasma glucose level.

The effect of alteration of eating pattern during Ramadan on body mass index (BMI), serum fructosamine: total protein ratio (F/TP), and glucose level in 18 healthy male Asiatic Moslems were studied. The results showed a significant decrease (p less than 0.025) in F/TP at the second week of Ramadan in 11 subjects who experienced continuous decrease in BMI throughout Ramadan. The remaining 7 subjects showed no significant changes in BMI and F/TP. No evidence of hypoglycaemia was observed in the subjects during the study. Serum fructosamine: total protein ratio in subjects with altered eating pattern preferably should be interpreted along with the change in body mass index.

Adult↗
PubMed1988

In vitro glycation of dried serum.

In vitro glycation of sera dried on water-resistant medium (Parafilm) and on paper were studied by measuring the change of glucose level, fructosamine:total protein ratio, glycated protein concentration and alteration of electrophoretic mobility of sera before and after drying. The results suggested the instability of glucose in dried sera was due to in vitro glycation which was influenced by surface properties of media on which the sera were deposited. A new method for rapid effective in vitro glycation of sera was also proposed.

Blood Chemical Analysis↗
PubMed1987

Effects of fasting in Ramadan on tropical Asiatic Moslems.

1. Anthropometric variables, resting heart rate and respiratory gas exchange were measured in twelve male and nine female Asiatic adult Moslems during the month of Ramadan, the week before and the month after Ramadan. 2. Energy intakes were estimated from dietary recall during fasting and non-fasting conditions. 3. Both male and female subjects experienced a decrease in body mass with the reduction in energy intake during fasting. Males experienced a greater reduction than females in resting heart rate; females lost more body-weight and subcutaneous fat than males. 4. Urine output and fluid intake were measured in twelve male subjects for 1 d during each week of fasting and 1 d during the pre-fasting control period. Among the subjects examined, the Ramadan regimen did not result in changes in the pattern of fluid exchange.

Adult↗
PubMed1987

Dissociation of hepatitis B surface antigen (HBsAg) from immobilised anti-HBsAg antibody in a two site immunoradiometric assay: its relevance to hook effect and recycled assay.

The mechanism of the hook effect in a two site immunometric assay of hepatitis B surface antigen (HBsAg) was studied using a novel method. The results showed that HBsAg dissociated from immobilized anti-HBsAg at low as well as high doses of antigen (Ag). This probably was not due to lack of immobilized antibody (Ab) or dissociation of HBsAg non-specifically bound to the immobilized Ab. The dissociated Ag sequestered the labelled Ab in the second reaction and contributed to the decrease in percent binding (B%) of the assay and thus the hook effect. The dissociated Ag could contaminate the recovered pooled labelled Ab in recycled assay and give rise to high non-specific binding. Prolonged washing decreased the side reaction but also the B% of the assay.

Antigen-Antibody Reactions↗
PubMed1987

Cerebral metastases from choriocarcinoma. Results of chemotherapy.

Of 36 cases of choriocarcinoma treated at the University Hospital Kuala Lumpur during 1980-84 inclusive, 6 patients were found to have cerebral metastases. Intrathecal methotrexate and combination chemotherapy were started in all cases, with monitoring of tumor growth by serial beta-HCG assays and CT scanning of brain and lung. Chemotherapy was reduced because of severe toxicity in 2 patients, one of whom received radiotherapy to the brain. Four patients (66%) have now been in remission for 2.5-6 years. Two did not respond to therapy and died. The factors involved in therapy and response are discussed.

Adult↗
PubMed1985

A novel method for the detection of variation in solid-phase immobilised antibody concentration and its possible application in quality control in immunoassay.

Variation of solid-phase antibody concentration could give rise to poor intra- and interassay precision. A new method to detect this variation is reported. Pooled sera with thyroxine (T4) values at the low, medium, and high ranges were assayed in duplicate using anti-T4-coated polystyrene beads. The antigen-antibody complexes were dissociated with methanol-water mixture and the antibodies re-used for subsequent T4 assays in which the same beads were used with the same set of standards and pooled sera. A second set of assays using randomised beads after each assay-wash cycle were also carried out. The variations in weights and surface structures of the beads were also studied. The variation of T4 results of group methods using polyethylene glycol in an external quality control program was also compared with that of covalently linked solid-phase particulate antibody methods over 2 periods. The experimental results showed that there was bead-to-bead variation of antibody concentration which could give rise to poor precision. Rigorous control of the immobilised antibody concentration could further improve the assay performance.

Antibodies↗