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Biomedical subjects

R Guan

Publications and source records attributed to R Guan.

At least 91 records · Page 5Linked to original sources
PubMed1986

A preliminary survey on aflatoxin exposure in Singapore.

Aflatoxins (naturally occurring chemicals of fungal origin) are powerful liver carcinogens, and increased incidence of hepatocellular carcinoma has been observed in areas where exposure to this mycotoxin is high (e.g., Africa, China). These areas also have a high incidence of HBV infection. It has been suggested that this environmental carcinogen interact with HBV in the aetiogenesis of hepatocellular carcinoma in these areas. The aim of this study was to determine the level of aflatoxin exposure in the local population. Fifty healthy adults were studied. Details of dinner taken the previous evening were obtained. Early morning urine was collected and aflatoxin quantitated by ELISA following purification on an antibody affinity column. Rabbit polyclonal antibody to aflatoxin B1 was used, and the mean of at least two assays were determined. Six individuals (12%) showed ELISA inhibition values of more than 25%, equivalent to aflatoxin levels of more than 100 pg/ml in urine. Levels ranged from 185 pg/ml to 2300 pg/ml aflatoxin B1 equivalents. All 6 individuals consumed fried food. The highest level was found in a medical student who had 'satay' (crushed peanut) sauce with dinner. This is in contrast to 52% individuals from Gambia with urine aflatoxin levels between 100 and 1000 pg/ml.

Adult↗
PubMed1986

Wilson's disease revisited in the tropics.

The clinical features and investigations of 17 patients were analysed. Thirteen of them were Chinese and the rest Indians. Their ages at presentation ranged from 8 to 63 years (mean 18.35 years). Thirteen patients (76%) were symptomatic; 8 with predominantly hepatic manifestations and 5 with neurological features. Four were asymptomatic siblings. At diagnosis, however, 10(59%) had features of liver involvement singly, 3 (18%) had neurological involvement alone and 4 (27%) had mixed presentations. Family histories were available in 15 patients; 26.9% of siblings had Wilson's Disease. Serum ceruloplasmin was low in 82% of the patients. 24-hour urinary copper was measured in 16 patients and was raised in all of them. About half the patients (41%) had evidence of concomittant renal tubular dysfunction with hypouricaemia and aminoaciduria. Three patients (18%) had joint involvement at presentation. All 17 patients were treated with Penicillamine. Complications due to therapy included pemphigus in one and toxic epidermal necrolysis and later a lupus like syndrome in another. The features of clinical improvement included fading of K-F rings, improvement of neurological signs and the normalisation of serum transaminases. One patient developed primary hepatocellular carcinoma 5 years after presentation. Delay in diagnosis was encountered in half of the patients reviewed. Being a treatable condition, Wilson's Disease, although rare, should always be thought of in patients with haemolysis, liver diseases or extrapyramidal disorders.

Adolescent↗
PubMed1986

Congenital enzymopenic methaemoglobinaemia.

Methaemoglobin is haemoglobin in which the sixth coordination position of heme iron is in the ferric state, having lost an unpaired electron. In normal human blood the level of methaemoglobin is 1% or less. This stable level results from an equilibrium between the rate at which ferric heme is formed and the rate at which it is reduced back to the ferrous state. Congenital methaemoglobinaemia caused by a deficiency or absence of methaemoglobin reductase represents a disturbance of this equilibrium wherein the methaemoglobin formed at physiological rate is not efficiently reduced. A chronically elevated level of oxidized haemoglobin results. Methaemoglobin is incapable of binding oxygen. Instead of the bright red colour imparted by oxyhaemoglobin, blood containing more than 10% methaemoglobin is dark brown. A concentration exceeding 1.5 g/d1 gives rise to cyanosis. The majority of patients with congenital enzymopenic methaemoglobinaemia are asymptomatic despite the intense cyanosis. This is a very important differentiating point from the cyanosis of cardiopulmonary causes. Methaemoglobin reductase deficiency is uncommon. Most proven cases had been in persons of European descent with sporadic reports of non-Caucasoid patients. We report here a Chinese patient whom we believe is the first in South East Asia to have methaemoglobin reductase deficiency unequivocally documented.

Adult↗
PubMed1985

Primary hepatocellular carcinoma associated with Wilson's disease in a young woman.

A 27 year old woman with hepato-lenticular degeneration (Wilson's disease) was found to have primary hepatocellular carcinoma (PHC) three and a half years after she was started on treatment with D-penicillamine. The tumour was resected since when she has remained well. Her liver function tests were normal throughout the course of her disease. The available literature is reviewed and possible mechanisms for this association proposed.

Adult↗
PubMed1983

The influence of sex, race and dialect on peptic ulcer and non-ulcer dyspepsia in Singapore.

A consecutive series of 2,277 patients presenting for upper gastrointestinal endoscopy was analysed. The following groups of patients were studied with reference to sex, race and dialect groups: those presenting with dyspepsia but no haemorrhage, those presenting with upper gastrointestinal haemorrhage, those with non-ulcer dyspepsia, gastric ulcer and duodenal ulcer. Males out-numbered females in all diagnostic groups. Male and female Malays were under-represented in all diagnostic groups when compared to the Singapore population. Amongst female Chinese, there was an excess of Cantonese patients and an under-representation of Teochew patients in most diagnostic groups. These dialect differences were not remarkable amongst male Chinese. The possible reasons for these differences and their significance are discussed.

Adolescent↗
PubMed1983

The use of one gram daily cimetidine in the treatment of peptic ulcer in Singapore.

An open study was conducted to assess the efficacy of Cimetidine one gram daily in the treatment of peptic ulcer amongst outpatients in Singapore. Forty patients with duodenal ulcer and fourteen patients with gastric ulcer were entered into the study. Ulcer healing was assessed by endoscopy. At six weeks 85% of duodenal ulcers and 64% of gastric ulcers healed. Although the study is uncontrolled the figures suggest that Cimetidine I gram daily is effective in the treatment of duodenal ulcer in Singapore outpatients. The efficacy of Cimetidine in gastric ulcer, however requires further study.

Adult↗
PubMedDate not supplied

Horizontal or vertical transmission of hepatitis B virus? A serological survey in family members of hepatitis B carriers in Singapore.

Hepatitis B serology was performed on 270 family members of 78 hepatitis B carriers and hepatitis B e antigen status determined in those found to be HBsAg positive. The mean age of index patients was 38 years (range 3-74) and that of family members was 28 years (range 1-71). 67 family members (25%) were HBsAg positive. The proportions of family members positive for HBsAg and those negative for HBsAg but positive for anti-HBs and/or anti-HBc were 25% and 20% for children, 10% and 68% for spouses, 36% and 26% for siblings and 29% and 55% for parents. For children of index parents the proportions positive for HBsAg and those negative for HBsAg but positive for anti-HBs and/or anti-HBc were similar whether the index patient was the mother (24% and 24%) or the father (26% and 18%). Our results suggest that horizontal transmission is a significant mode of spread of hepatitis B within the family in Singapore.

Adolescent↗
PubMedDate not supplied

Hepatitis A sero-epidemiology in Singapore: a changing pattern.

Sera from 896 healthy volunteers between 15 and 56 years old were tested in 1987-1991 for immunoglobulin G antibody against the hepatitis A virus (IgG anti-HAV). The overall seroprevalence rate of IgG anti-HAV was 27%: it increased from 0.9% in the 10-19 years age group to 48.1% in the 40-49 years age group and was 100% in subjects over 50 years. There was no difference in anti-HAV seroprevalence between the sexes (29% among men and 26% among women) and races. A downward trend in anti-HAV seroprevalence was seen from 1987 (33%) to 1991 (21.4%). The level of exposure to the hepatitis A virus has decreased when compared with data obtained in 1975 and 1984-1985. Hepatitis A virus infection is no longer an infection of children and adolescents locally.

Adolescent↗
PubMedDate not supplied

Low-dose cimetidine in the acute treatment of duodenal ulcer. Comparison of a single nocturnal dose regimen with a twice daily regimen.

A 0.5 g daily dose of cimetidine was as effective as a 1 g dose in the acute treatment of duodenal ulcer patients in Hong Kong. The aims of the present study were, first, to determine whether low-dose cimetidine treatment was as effective as standard doses in acute duodenal ulcer treatment of patients in Singapore, and second, to compare a single nocturnal dosage regimen with a twice daily regimen. In this single centre, double-blind, controlled trial, 282 patients with endoscopically proven duodenal ulcer were randomized to receive four weeks' treatment with cimetidine using one of three dosage regimens: (A) 800 mg at night; (B) 400 mg at night; or (C) 400 mg twice daily. Two hundred and forty-seven patients were evaluated. The incidences of healing at four weeks were: (A) 40/80 (50%), (B) 39/88 (44%); and (C) 48/79 (61%); (B vs C: P less than 0.05; A vs C: NS; 95% confidence limits: -5% to 27%; A vs B: NS, 95% confidence limits: -6% to 21%). Of 183 patients who had antral biopsies taken, 176 (96%) had histological gastritis, while 167 (91%) were positive for Helicobacter-like organisms. The occurrence of gastritis or Helicobacter-like organisms had no influence on ulcer healing. A 400 mg dose of cimetidine is therefore suboptimal for the treatment of duodenal ulcer in patients in Singapore. A single nocturnal dosage regimen may be less effective than a twice daily regimen.

Adult↗
PubMedDate not supplied

Antibody to herpes simplex virus type 1 in peptic ulcer patients.

It has been postulated that herpes simplex virus type 1 may be a causative factor of duodenal ulcer. Serum antibody titres to herpes simplex virus type 1 in duodenal and gastric ulcer patients were compared with race-, sex- and age-matched controls. No differences in antibody titres could be demonstrated between duodenal ulcer and gastric ulcer patients and their respective controls, between gastric ulcer and duodenal ulcer patients or between acute and convalescent sera in either gastric or duodenal ulcer. Although Chinese are more susceptible to ulcer disease than Malays and Indians, antibody titres were comparable between subjects of different races. The results of this study do not support a causal role for herpes simplex virus in peptic ulcer disease.

Adult↗