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Biomedical subjects

R Guan

Publications and source records attributed to R Guan.

At least 73 records · Page 4Linked to original sources
PubMed1990

Helicobacter pylori and gastritis in patients with peptic ulcer and non-ulcer dyspepsia: ethnic differences in Singapore.

Peptic ulcer occurs with different frequencies in the three main racial groups in Singapore. This study aimed firstly to determine the prevalence of Helicobacter pylori in peptic ulcer and non-ulcer dyspepsia patients of the different races and secondly, to assess the relation between H pylori, histological gastritis, patient diagnosis, and race. Gastric antral biopsy specimens from 1502 patients undergoing gastroduodenoscopy were studied and 892 (59%) were positive for H pylori. H pylori was strongly associated with gastritis: 873 of 1197 (73%) patients with gastritis were positive compared with 19 of 305 (6%) without gastritis (p less than 0.0001). The prevalences of H pylori and gastritis were similar in peptic ulcer patients of different races. Malay patients with non-ulcer dyspepsia, however, were less likely to be positive for H pylori (10 of 46 (22%] or to have antral gastritis (17 of 46 (37%] than Chinese (292 of 605 (48%) were positive for H pylori and 421 of 605 (70%) had gastritis) and Indians (35 of 61 (57%) were H pylori positive and 42 of 61 (69%) had gastritis). Patients with duodenal ulcer were more likely to be positive for H pylori than those with non-ulcer dyspepsia, even when subjects with gastritis were considered separately. While our results do not help to explain the observed racial differences in peptic ulcer frequency it may be that the pathophysiology of non-ulcer dyspepsia is different in the different races in Singapore.

Adult↗
PubMed1990

Comparison of culture and histology for the identification of Helicobacter pylori in endoscopic biopsies.

The aim of the study was to compare culture with microscopic examination of haematoxylin and eosin stained tissue sections in the identification of Helicobacter pylori in gastric antral mucosa. Duplicate gastric antral biopsies from 89 patients were cultured and examined histologically for H pylori. H pylori was cultured in 46 cases (51%) and identified histologically in 63 (71%). Results from the two tests concurred in 63 cases (71%). The presence of H pylori was strongly correlated with histological gastritis. Microscopic examination of haematoxylin and eosin stained tissue sections is therefore a reliable and convenient method of identifying H pylori.

Campylobacter↗
PubMed1990

Hepatitis B vaccination in chronic renal failure patients undergoing haemodialysis: the immunogenicity of an increased dose of a recombinant DNA hepatitis B vaccine.

Thirty-two patients with end stage renal failure who were on haemodialysis and who had no previous exposure to hepatitis B virus were given four intramuscular injections of 40 micrograms (twice the recommended dose) recombinant DNA hepatitis B vaccine (Engerix B, Smith Kline Biologicals) at 0, 1, 2 and 6 months to determine the immunogenicity of this increased vaccine dose. The ages of these patients ranged from 23-54 years with a mean age of 40 years. There were 11 males and 21 females. Three patients underwent renal transplantation during the course of the study and were assessed separately. Antibody levels above 10 IU/L were noticed in 83% of the remaining 29 patients two months after the final dose with an anti-HBs geometric mean titre (GMT) of 2551 IU/L. The antibody response was 82% four months later although the GMT has fallen to 664 IU/L. Renal transplantation did not appear to affect the anti-HBs response to the above vaccination regime. None of the volunteers developed hepatitis B during the study. Our results were much better than results obtained in studies using twice the recommended doses given three times.

Adult↗
PubMed1990

Endoscopic retrograde cholangiopancreatography and endoscopic sphincterotomy--a Singapore experience.

We performed endoscopic retrograde cholangiopancreatogram (ERCP) on 200 patients over a four and a half year period. The duct of interest was successfully cannulated in 173 cases (87%). The most common indications were obstructive jaundice, cholangitis, chronic upper abdominal pain and suspected pancreatic disease. The commonest findings were cholelithiasis and malignant strictures of the common bile duct (CBD). Forty seven patients (27%) had normal examinations. Sixty-two of 87 (71%) patients with choledocholithiasis underwent endoscopic sphincterotomy (ES). The success rate for active stone extraction was 82% (27/33) while 64% (14/22) of patients managed expectantly cleared their CBD stones spontaneously after ES. The immediate complication rate of ES was 13% and included pancreatitis, stone impaction, cholangitis and bleeding. There was no complications amongst patients who underwent ERCP alone and no mortality in this series. Twenty three patients (26%) with choledocholithiasis proceeded to surgery because the stones were considered too large to remove endoscopically. One patient had endoscopic stone removal without prior ES while another had a permanent stent inserted for drainage. We conclude that ERCP and ES are useful and safe modalities in the assessment of biliary tract diseases and the treatment of choledocholithiasis.

Adult↗
PubMed1990

Experience with endoscopic biliary drainage in Singapore.

In several overseas centres endoscopic biliary drainage is now a standard procedure in the initial or definitive management of biliary tract obstruction. We report the first nine patients in whom this procedure was carried out in our unit. Four patients presented with acute cholangitis due to cholelithiasis. Urgent endoscopic biliary drainage improved the general condition in three patients prior to subsequent elective surgery. In one other patient with huge common bile duct calculi a biliary stent prevented recurrent episodes of cholangitis. Endoscopic endoprostheses were used in three patients with malignant biliary tract obstruction. Two had terminal metastatic disease and endoscopic drainage provided adequate palliation of jaundice and pruritus in one. Endoprosthesis blockage necessitated percutaneous drainage in the other patient. The third patient with carcinoma of the head of the pancreas was improved by endoscopic drainage prior to an open surgical bypass procedure. Another patient with obstructive jaundice due to terminal gall bladder carcinoma experienced relief of jaundice and pruritus following endoscopic insertion of a nasobiliary drain. We anticipate that endoscopic biliary drainage will become increasingly used in Singapore.

Aged↗
PubMed1989

Acid induced duodenal ulcer pain: the influence of symptom status and the effect of an antispasmodic.

The aims of this study were to determine whether the development of acid induced duodenal ulcer pain was influenced by the symptomatic status of the patient and whether the administration of an antispasmodic could abolish pain. One hundred millilitres of 0.1 N hydrochloric acid was infused onto the ulcer craters or scars of 143 duodenal ulcer patients on 168 occasions. Symptomatic patients were randomised to receive 40 mg of hyoscine intravenously before acid infusion, or to a control group. Typical ulcer pain developed in seven of 55 (13%) instances for non-symptomatic patients, 24/57 (42%) of control symptomatic patients, and 20/56 (36%) of symptomatic patients given hyoscine. (Asymptomatic group v control symptomatic group, p less than 0.005; control symptomatic group v hyoscine group, NS - 95% confidence limits 12% in favour of the control and 24% in favour of the hyoscine group). The results suggest that acid infusion seldom reproduces ulcer pain in non-symptomatic duodenal ulcer patients and that the pathogenesis of acid induced duodenal ulcer pain probably involves a mechanism other than spasm, as pain was not prevented by an anticholinergic.

Adolescent↗
PubMed1989

Immunogenicity of a low dose recombinant DNA hepatitis B vaccine in healthy adults in Singapore.

The immunogenicity and safety of a standard dose of 10 micrograms of a yeast derived recombinant DNA hepatitis B vaccine (B-Hepavac II) was compared with that of a reduced dose of 5 micrograms in 84 healthy adult volunteers with no previous exposure to hepatitis B. Each subject received either a 10 micrograms or 5 micrograms dose of vaccine intramuscularly at 0, 1 and 6 months. One month after the second injection of vaccine the seroconversion rate in the two groups were 85 and 86 percent respectively. Two months after the third injection 100 percent of participants had sero-converted; 95 percent of the 10 micrograms group and 91 percent of the 5 micrograms group had titres of anti-HBs greater than 10 IU/L. The geometric mean titres (GMT) of anti-HBs levels at 2, 6, 8, and 12 months were 34, 61, 811 and 188 IU/L in the 10 micrograms group and 26, 45, 836 and 304 IU/L in the 5 micrograms group respectively. Adverse effects were mild and transient. The vaccine was safe and immunogenic in the doses given. The reduced dose of 5 micrograms was as effective as the standard 10 micrograms dose.

Adolescent↗
PubMed1989

Evidence of viral replication in HBsAg positive patients with hepatocellular carcinoma: measurement of serum hepatitis B virus deoxyribonucleic acid (HBV-DNA).

Sera from 60 consecutive patients with hepatocellular carcinoma (HCC) diagnosed by either a positive histology or at least two of the following: CT scan, hepatic ultrasound, hepatic angiogram and raised alpha-foetoprotein levels, were studied to determine their Hepatitis B surface antigen (HBsAg) status and the frequency of continuing viral replication. Markers of Hepatitis B virus (HBV) infection were detected using enzyme and radioimmunoassays. Hepatitis B DNA (HBV-DNA) was measured by molecular hybridization using a labelled recombinant HBV-DNA probe. Sera from 30 HBsAg positive 'healthy' carriers were used as controls. Forty-seven (78%) patients were HBsAg positive. Evidence of previous HBV infection was present in 12 of 13 HBsAg negative patients. 30% of HBsAg positive patients were HBeAg positive, 62% were anti-HBe positive and 8% had no 'e' markers. Serum HBV-DNA was present in 21 (45%) HBsAg positive patients: 10 (71%) HBeAg positive patients, 10 (35%) anti-HBe positive patients and 1 (25%) patient without any 'e' markers. Serum HBV-DNA levels were less than 0.6 ng/ml in 16 (76%) patients. HBV-DNA was absent in all HCC patients who were HBsAg negative. The frequency of serum HBV-DNA positivity was higher in 30 patients with HCC when compared with 30 age and sex matched healthy HBsAg positive individuals (57% vs 13% p less than 0.01). A sizeable proportion of HBsAg positive HCC patients have on-going viral replication and this is present in patients who were thought to have stopped replicating (anti-HBe positive patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

The prevalence of hepatitis B virus markers in dental personnel in Singapore.

A seroepidemiological survey of the prevalence of hepatitis B virus (HBV) markers was conducted in a group of 693 dental personnel in Singapore where HBV infection is endemic. The overall prevalence of HBsAg (4.5%) and anti-HBc (29%) was no higher than that in the general population. However, dentists had a significantly higher HBsAg prevalence (11.4%) compared with that in the general population (4.2%) (P less than 0.01) and of other categories of dental personnel (3.1%) (P less than 0.001). Similarly, the anti-HBc prevalence of the dentists (45.6%) was significantly higher than that of the general population (29.7%) (P less than 0.01) and of other categories of dental personnel (25.7%) (P less than 0.0001). It appears that dentists in the endemic area have a definite occupational risk of acquiring HBV infection.

Dental Staff↗
PubMed1988

Dietary supplementation with pectin in the maintenance treatment of duodenal ulcer. A controlled study.

Patients with recently healed duodenal ulcers diagnosed by endoscopy were randomly allocated to receive 10 g apple pectin USP powder twice daily, 150 mg ranitidine at night, or one tablet matching ranitidine placebo at night for 6 months. Repeat endoscopy was performed at 6 months or if symptoms recurred. Eighty-three patients completed the study. Recurrences occurred in 23 of 27 (85%) patients taking pectin, 6 of 28 (21%) patients taking ranitidine, and 20 of 28 (71%) patients taking placebo. (Pectin versus placebo, NS; ranitidine versus pectin, p less than 0.00001; ranitidine versus placebo, p less than 0.0005). The average amount of pectin taken was 12.7 g/day in patients who relapsed and 12.4 g/day in those who did not. At the doses taken, therefore, dietary supplementation with pectin did not reduce the incidence of duodenal ulcer relapse.

Adult↗
PubMed1988

Clinical evaluation of a yeast recombinant hepatitis B vaccine in healthy hospital staff in Singapore.

A yeast recombinant hepatitis B vaccine (subtype adw), derived from purification of HBsAg particles, expressed in the yeast Saccharomyces cerevisiae which contained the gene for HBsAg, was evaluated in 31 healthy adult hospital staff members in Singapore. Each subject received a 10 mcg dose of vaccine intramuscularly at 0, 1 and 6 months. One month after the first two injections of vaccine the seroconversion rate (defined as greater than or equal to 2.7 mIU/ml) was 90%. Two months after the third injection 100% of participants had anti-HBs levels higher than 2.7 mIU/ml and 97% had titers of anti-HBs greater than 10 mIU/ml. The geometric mean titer (GMT) of anti-HBs levels at 2, 3, 6, 8 and 12 months were 21.9, 38.6, 57.6, 1253.4 and 354.1 mIU/ml, respectively. All clinical complaints were mild and transient. They consisted of mild soreness at the injection site, transient fever and headache. There was no correlation between the presence of antibodies to S. cerevisiae with any allergic manifestations. The vaccine was safe and immunogenic for staff exposed to an infection risk and should now be widely used in the extension of hepatitis B immunization programs.

Ethnicity↗
PubMed1987

Cellular hypersensitivity to gluten derived peptides in coeliac disease.

Wheat gluten derived antigens have been tested for their ability to inhibit the migration of leucocytes from healthy subjects and patients with coeliac disease. Three preparations of a water soluble fraction (Frazer's fraction III, FIII) of partial peptic tryptic digests of wheat gluten had different effects in a direct (one stage) assay. Subfractions B and B2 caused migration inhibition of leucocytes from patients with treated coeliac disease but not of leucocytes from healthy volunteers or patients with Crohn's disease or ulcerative colitis. This migration inhibition seems to be specific for gluten fractions because maize zein fraction B, beta-lactoglobulin and ovalbumin did not cause it. The sensitivity of coeliac leucocytes to fraction B is not related to factors present in coeliac serum as the migration of leucocytes from healthy individuals preincubated with coeliac sera was not inhibited. Puromycin diminished inhibition by fraction B, which was active at 1.2 micrograms/ml in an indirect (two stage) migration inhibition assay; this is consistent with a process involving elaboration of lymphokine(s). More highly purified fractions of B2, P1-P4 were prepared by reverse phase high performance liquid chromatography (HPLC) and showed differing potency in direct and indirect assays, with P4 being the most active fraction. Inhibition of migration by gluten derived peptides appears to result from the release of lymphokine by leucocytes specifically from coeliac patients.

Antigens↗
PubMed1987

Abdominal tuberculosis revisited.

Four patients with abdominal tuberculosis (ATB) managed in the University Department of Medicine, Singapore General Hospital, are presented to highlight problems encountered in the diagnosis of this condition. Three patients had intestinal tuberculosis, one of whom had peritoneal involvement and another had possible hepatic disease. The fourth patient presented with peritoneal disease alone. Ages at presentation ranged from 25 years to 71 years. There were three females and one male. Two patients presented with symptoms of chronic illness for 10 months before the disease was diagnosed. Two other patients had acute presentations. Fever, abdominal pain, vomiting and diarrhoea were the main symptoms encountered. Three patients had abdominal masses at diagnosis. Radiological investigations were the most useful diagnostic aid. Bacteriological confirmation was made in only one patient. Histology helped in the diagnosis in two others. Recent literature on this condition was reviewed and the possible role of impaired immunity in the pathogenesis of this condition was discussed.

Adult↗
PubMed1986

Influence of the site of a duodenal ulcer on its mode of presentation.

The aims of this study were to define the localization of duodenal ulcer and to determine whether the site influenced the initial presentation. Eight hundred eighty-four duodenal ulcer patients diagnosed by endoscopy in Singapore and Sydney were studied. The ulcer was situated on the anterior wall of the bulb in 49% and the posterior wall of the bulb in 23%. The distribution was not influenced by sex, age, or the center of diagnosis. Those situated posteriorly in the bulb were more likely to present with hemorrhage than those situated elsewhere.

Adult↗
PubMed1986

Acid perfusion of duodenal ulcer craters and ulcer pain: a controlled double blind study.

Although early studies attributed an important role to acid in the pathogenesis of duodenal ulcer pain, recent reports are conflicting. The aim of the present study is to determine whether direct acidification of the duodenal ulcer crater in symptomatic patients reproduces ucler pain. Patients with endoscopically diagnosed duodenal ulcers were studied. No premedication or sedation was given. A washing tube was passed via the endoscope and 0.1 N hydrochloric acid as well as normal saline were sequentially administered on to the ulcer crater, the sequence of infusion being randomised and double blind. Forty patients were studied. Sixteen developed typical ulcer pain during acid infusion compared with four with saline (p less than 0.005). Ten patients who developed pain on acid were rechallenged with acid after their pains disappeared. Typical pain recurred in all. Twenty patients without duodenal ulcer did not develop pain when 200 ml of 0.1 N hydrochloric acid was infused into the duodenum. Acid therefore appears to have a definite role in the pathogenesis of duodenal ulcer pain although other factors may also be important.

Adult↗