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Biomedical subjects

I Yap

Publications and source records attributed to I Yap.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1989

Randomised controlled trial of lymphoblastoid interferon alfa in Europid men with chronic hepatitis B virus infection.

OBJECTIVE: To confirm the findings of pilot studies that interferon alfa is an effective treatment of Europid men with chronic hepatitis B virus infection. DESIGN: Randomised controlled trial of three months treatment with interferon alfa followed by 12 months of observation. SETTING: Outpatient clinic of a tertiary referral centre. PATIENTS: 37 Treated men (six anti-HIV positive) and 34 untreated men (nine anti-HIV positive) who met the criteria for the trial. Four controls failed to complete follow up. INTERVENTIONS: The treated group received subcutaneous injections of 5-10 MU interferon alfa/m2 daily for five days, then 10 MU/m2 thrice weekly for 11 weeks. Follow up continued at monthly intervals for 12 months. Untreated controls were monitored over the same period. MAIN OUTCOME MEASURE: Hepatitis B e antigen and hepatitis B virus DNA state after 15 months of observation. RESULTS: 12 Of the 37 treated patients cleared hepatitis B e antigen and hepatitis B virus DNA, whereas only one of 30 untreated controls seroconverted over the same period--an increased response rate of 29% (95% confidence interval 13% to 45%). The life table estimate of response at 15 months was 35% in treated patients, an increase of 32% above controls (95% confidence interval 16% to 48%). The response rates in groups by predictive pretreatment variables were 12 of 31 anti-HIV negative patients (excess response 34%; 95% confidence interval 14% to 54%), 12 of 26 with chronic active hepatitis before treatment (excess response 46%; 27% to 65%), and 12 of 21 with a pretreatment serum aspartate aminotransferase activity greater than 70 IU/l (excess response 46%; 16% to 76%). The combination of these factors predicted response with a sensitivity of 100% and a specificity of 80%. Four of the 12 responders, who had all been infected for less than two years, also lost hepatitis B surface antigen. Treatment was well tolerated. CONCLUSIONS: Interferon alfa is effective in the treatment of a proportion of Europid men with chronic hepatitis B virus infection, who might be identified before treatment. Additional strategies are required to improve the rate of response.

Adolescent↗
PubMed1989

Lactase deficiency in Singapore-born and Canadian-born Chinese.

Seventy-three of 77 adult Singapore-born Chinese (95%) and 48 of 49 Canadian-born adult Chinese (98%) were demonstrated to be lactase deficient using the lactose breath hydrogen test. The similar prevalence of lactase deficiency in the Singapore- and the Canadian-born Chinese despite a larger estimated amount of daily milk ingestion in the Canadian-born Chinese (430 ml vs 157 ml) supports the concept that lactase deficiency, which is transmitted genetically, does not have an adaptable component related to the quantity of lactose ingested. When the lactose breath hydrogen test performed with a dose of 0.5 g/kg of lactose was compared with the test using a standard dose of 50 g of lactose, there was very little loss of sensitivity. In spite of the presence of lactase deficiency, only 32% of the Singapore subjects and 23% of the Canadian subjects had gastrointestinal symptoms when milk was ingested in the daily diet. Peak breath H2 was higher in females than males, but the difference was more significant in the Canadian cohort.

Adolescent↗
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

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↗
PubMed1987

A review of the efficacy of adenine arabinoside and lymphoblastoid interferon in the Royal Free Hospital studies of hepatitis B virus carrier treatment: identification of factors influencing response rates.

We have reviewed the results of treating over 100 HBV carriers with adenine arabinoside, adenine arabinoside monophosphate and lymphoblastoid interferon. In the homosexual group of carriers, adenine arabinoside and its monophosphate have no value. However in this group, lymphoblastoid interferon will produce a response in over 50% of cases. This lack of effectiveness of adenine arabinoside monophosphate in this group may stem from its immunosuppressant properties. In heterosexual carriers both adenine arabinoside monophosphate and lymphoblastoid interferons are effective in approximately 50% to 60% of cases. However, the response rate is different in the various racial groups. Northern European and Mediterranean people appear to respond whereas those from the Far East do not. This may reflect the fact that there are at least two mechanisms by which the chronic carrier state may arise. In 5% to 10% of adults, a relative deficiency of alpha interferon production exists, and this defect is found in the majority of HBV carriers in Western Europe. In these, interferon acts as a replacement therapy and excellent results may be obtained if the patient is treated early in the course of the disease. It would appear that as the duration of the infection increases, the virus may integrate into interferon-reactive consensus sites and prevent the cell from responding to interferon. In patients infected at birth, transplacental anti-HBc appears to modulate the immune response and, along with immaturity of the immune system at this age, results in failure to lyse infected cells. These patients do not benefit from interferon treatment: some form of immune manipulation is required.(ABSTRACT TRUNCATED AT 250 WORDS)

Arabinonucleotides↗
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

Identification of factors influencing response rate to antiviral therapy of chronic hepatitis B virus infection. A review of the efficacy of adenine arabinoside and lymphoblastoid interferon in the Royal Free Hospital studies.

We have reviewed the results of treating over 100 HBV carriers with adenine arabinoside, adenine arabinoside monophosphate and lymphoblastoid interferon. In the homosexual group of carriers, adenine arabinoside and its monophosphate have no value. However, in this group, lymphoblastoid interferon will produce a response in over 50% of cases. The lack of effectiveness of adenine arabinoside monophosphate in this group may stem from its immunosuppressant properties. In heterosexual carriers both adenine arabinoside monophosphate and lymphoblastoid interferon are effective in approximately 50-60% of cases. However, the response rate is different in the various racial groups. Northern European and Mediterranean people appear to respond whereas those from the Far East do not. This may reflect the fact that there are at least 2 mechanisms by which the chronic carrier state may arise. In 5-10% of adults, a relative deficiency of alpha-interferon production exists and this defect is found in the majority of HBV carriers in Western Europe. In these, interferon acts as a replacement therapy and excellent results may be obtained if the patient is treated early in the course of the disease. It would appear that as the duration of the infection increases, the virus may integrate into interferon-reactive consensus sites and prevent the cell from responding to interferon. In patients infected at birth, transplacental anti-HBc appears to modulate the immune response and along with immaturity of the immune system at this age, results in failure to lyse infected cells. These patients do not benefit from interferon treatment: some form of immune manipulation is required.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
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↗
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↗