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Biomedical subjects

I Yap

Publications and source records attributed to I Yap.

71 records · Page 4Linked to original sources
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↗
PubMedDate not supplied

Hepatitis B vaccination: half dose recombinant DNA hepatitis B vaccine (B-Hepavac II) is as immunogenic as the full recommended dose in healthy adults.

Sixty-seven healthy adult volunteers aged 20-40 years with no previous exposure to hepatitis B virus were randomized to receive either a 10 micrograms or 5 micrograms dose of recombinant DNA hepatitis B (HB) vaccine (B-Hepavac II) intramuscularly at 0, 1 and 6 months. Two months after the third injection 100% of subjects had seroconverted: 97% of the 10 micrograms group and 91% of the 5 micrograms group had antibody to HB surface antigen (anti-HBs) levels greater than 10 iu/L. The geometric mean titres (GMT) of anti-HBs levels at this time were 891 iu/L in the 10 micrograms dose group and 923 iu/L in the 5 micrograms dose group. These differences were not significant. Adverse effects included fever and mild pain at the injection site. The reduced dose of 5 micrograms was as effective as the standard 10 micrograms dose.

Alanine Transaminase↗
PubMedDate not supplied

Hepatocyte hepatitis B surface antigen expression in chronic hepatitis B virus carriers in Singapore: correlation with viral replication and liver pathology.

The hepatocyte hepatitis B surface antigen (HBsAg) expression in 149 liver biopsies from 124 chronic hepatitis B virus (HBV) carriers was correlated with serum HBV DNA status and histologic activity. Hepatocyte HBsAg was stained by the peroxidase-antiperoxidase method and serum HBV DNA was determined by dot blot hybridization. Sixty-five biopsies (44%) showed minimal changes (MC), 82 biopsies (55%) showed chronic liver disease (CLD) and 2 biopsies (1%) showed hepatocellular carcinoma. Hepatocyte HBsAg was found in 144 biopsies (97%). It was present in the cytoplasm of 141 specimens (95%) and/or plasma membrane of 48 specimens (32%). Approximately half (45%) of the cytoplasmic HBsAg-positive biopsies showed discrete distribution, while the other half (55%) were grouped. Fifty-five per cent (77 of 141) of cytoplasmic HbsAg-positive biopsies had CLD, while 44% (62 of 141) showed MC. There was no relationship between the presence of cytoplasmic HBsAg or its topographic distribution with disease activity. Membrane HBsAg distribution was similar for both groups of patients (MC vs CLD: 25 of 65 (38%) vs 23 of 82 (28%); P = NS). Serum HBV DNA was detected in 98 patients (66%) and was seen mostly in association with CLD (CLD vs MC: 61% vs 39%, P less than 0.001). It was also detected more often in the sera of patients with membrane HBsAg than in those with cytoplasmic HBsAg staining (41 of 48 (85%) vs 97 of 141 (67%); P less than 0.02). However, discrete distribution of cytoplasmic HBsAg was associated with positive serum HBV DNA when compared with grouped distribution (52 of 63 (83%) vs 43 of 78 vs (55%); P less than 0.005).

Carrier State↗
PubMedDate not supplied

Inflammatory bowel disease: an uncommon problem in Singapore.

Fifty patients with inflammatory bowel disease (ulcerative colitis, 40; Crohn's disease, seven; indeterminate colitis, three) treated in one gastroenterology unit in Singapore over a 10 year period were reviewed. Clinical features were similar to those described in Western patients. Of the three main races of Singapore it was found that Indians are more susceptible to these diseases than Chinese or Malays. A survey of all gastroenterologists in Singapore indicated a possible prevalence of 8.6 per 100,000 people for ulcerative colitis and 1.3 per 100,000 people for Crohn's disease. These prevalence rates are much lower than those reported for Western populations.

Adult↗
PubMedDate not supplied

Analysis of cost-effectiveness of different strategies for hepatocellular carcinoma screening in hepatitis B virus carriers.

A mathematical model was used to calculate the efficacy of screening to detect hepatocellular carcinoma at a resectable stage in hepatitis B virus carriers. Data relating to tumour incidence, efficacy of screening tests and tumour growth times were obtained from a literature review. Various tests were costed according to charges currently prevailing at the authors' institution. The cost per early tumour detected is inversely proportional to tumour incidence. It is relatively low for populations with high incidences of hepatocellular carcinoma for example, male carriers over the age of 30. Both the costs and the proportions of early tumour detected increase with increasing frequency of screening. However, the use of ultrasonography at 10 monthly intervals or both ultrasonography and alpha-fetoprotein estimation at yearly intervals will detect 90% of tumours early at a cost of S$20,000 (US$11,800) per early tumour detected. The results would be significantly altered if tumour growth times were markedly different from those reported in the literature.

Australia↗
PubMedDate not supplied

The pattern of functional and organic disorders in an Asian gastroenterological clinic.

The aim of the present study was to determine the pattern of structural and functional disorders encountered in an Asian gastroenterological clinic and to compare this pattern with findings from Western centres. Consecutive new patients (totalling 2384) attending the clinics of two consultant gastroenterologists were studied. Of these, 2141 suffered from gastroenterological problems. One thousand and sixty-three (49.6%) had structural diseases, the commoner ones being liver disease, peptic ulcer, malignancy, haemorrhoids and gallstones. The remainder who were found to have no structural disease (n = 1078; 50.4%) were deemed to have functional disorders including non-ulcer dyspepsia, irritable bowel, simple constipation and functional diarrhoea. The proportions of functional and structural disease were similar to those in the West. Major differences included a higher frequency of hepatoma and a lower frequency of inflammatory bowel disease and gastro-oesophageal reflux in the present series.

Adult↗
PubMedDate not supplied

Study on the comparative immunogenicity of a recombinant DNA hepatitis B vaccine containing pre-S components of the HBV coat protein with non pre-S containing vaccines.

A new recombinant hepatitis B vaccine (SCI-B-VAC), derived from Chinese hamster ovary (CHO) cells and consisting of both the major S protein and the minor pre-S1 and pre-S2 proteins of the viral coat were compared with two yeast-derived vaccines containing only S proteins (B-Hepavac II and Engerix-B) for immunogenicity in human volunteers in a randomized controlled study. Two hundred and ninety-five healthy subjects completed the 12 month follow up. There was no difference in the mean age and sex distribution among the three study groups. Seroconversion rates for all the three groups were similar at months 6, 9 and 12. However, hepatitis B surface antibody (anti-HBs) geometric mean titres (GMT) were significantly higher with 10 micrograms SCI-B-VAC and 20 micrograms Engerix-B than with 10 micrograms B-Hepavac-II at months 6, 9 and 12. SCI-B-VAC at month 6 also showed a significantly higher anti-HBs GMT than Engerix-B (295 vs 143 miu/mL, P < 0.02).

Adolescent↗
PubMedDate not supplied

Fine needle aspiration biopsy of small/intermediate cell tumors in the liver. Considerations in a southeast Asian population.

OBJECTIVE: To assess the diagnostic problems and accuracy involved in rendering an exact cytologic diagnosis, including reference to a primary site of origin, on fine needle aspiration biopsies (FNABs) of small/intermediate cell tumors of the liver. STUDY DESIGN: Thirty-five hepatic FNABs of small/ intermediate tumors, neuroendocrine tumors (NETs) and poorly differentiated or undifferentiated cancers occurring in adults were analyzed. Ancillary studies, including immunohistochemistry, were performed whenever necessary. All other relevant histopathologic sections and medical records were reviewed. RESULTS: There were 26 metastases, while 9 were considered primary lesions. The aspirates were categorized into 11 NETs (pancreas 5, lung 1, liver 2, unknown primary 3); 9 undifferentiated nasopharyngeal carcinomas; 2 small cell undifferentiated carcinomas (lung 2); 4 undifferentiated carcinomas, not otherwise specified (lung 1, pancreas 1, liver 1, unknown 1); 1 lobular-ductal carcinoma (breast); 1 glioblastoma multiforme (brain); 1 ovarian carcinoma; 1 non-Hodgkin's lymphoma (liver); and 5 primary hepatocellular carcinomas. CONCLUSION: There was histologic and/or immunohistochemical confirmation in 25 cases (71%). Some of the limitations in categorization of such tumors obtained by FNAB can be overcome by immunohistochemistry. Information gleaned from a precise cytologic diagnosis can sometimes only favor a particular primary site.

Adult↗
PubMedDate not supplied

Fine needle aspiration biopsy of hepatocellular carcinoma. Some unusual features.

The cytologic features of fine needle aspiration smears from 28 hepatocellular carcinomas (HCC) were reviewed. All aspirations except one were guided. There were 14 well-, 11 moderately and 3 poorly differentiated HCC. The better-differentiated HCC were characterized by similarity of the tumor cells to hepatocytes (83%), cohesive cell clusters with a trabecular arrangement (72%) and presence of sinusoidal endothelial cells (66%). Other features included bile production (38%), atypical hepatocytic naked nuclei (52%), acinar formation (31%), intracytoplasmic vacuoles (14%) and abnormal vascular patterns (14%). Poorly differentiated HCC showed dyshesive pleomorphic cells. Unusual cytologic features from a well-differentiated HCC with fatty change and an HCC with a prominent acinar component are described. The identification of fatty change in dissociated well-differentiated hepatocytes or cytologic features suggestive of an adenocarcinoma do not preclude the diagnosis of HCC. The usefulness of cell blocks is emphasized.

Adult↗
PubMedDate not supplied

Fine needle aspiration biopsy of hepatocellular carcinoma. Diagnostic dilemma at the ends of the spectrum.

A diagnostic dilemma exists at the extreme ends of the spectrum in the cytodiagnosis of hepatocellular carcinoma (HCC). The cytologic features of fine needle aspiration biopsies from 30 well- and 16 poorly differentiated HCC were reviewed and the adjunctive role of serum alpha-fetoprotein (AFP), hepatitis B virus (HBV) markers and radiologic findings evaluated. Some subtle features noted in very well differentiated HCC include small tumor cell size with increased nuclear/cytoplasmic ratio, monotony of atypia, hepatocytic tumor giant cells and narrow trabeculae with tendency for cell dissociation. Useful features in poorly differentiated HCC include cell dehiscence, large cells with ovoid nuclei and thickened nuclear membranes, and one or more increasingly prominent nucleoli, with some assuming a reniform configuration. The serum AFP levels are not always elevated. Positive HBV markers, cirrhosis and compatible imaging findings are suggestive but not diagnostic. The general inclination, however, is still toward a diagnosis of HCC if the aspirate is from a focal lesion or lesions in a hepatitis B surface antigen-positive, cirrhotic liver. Cell block sections provide histologic confirmation.

Adult↗
PubMedDate not supplied

Bile cytology. Diagnostic role in the management of biliary obstruction.

Thirty satisfactory bile specimens from 21 patients (13 with cancer and 8 with benign conditions) were reviewed to assess the diagnostic role of bile cytology in the management of biliary obstruction. Smears were malignant in 5 instances, suspicious in 1, atypical in 2 (8 in the positive group) and negative in 22. There were no false positives. The diagnostic sensitivity was 38%, specificity 100% and overall accuracy 57%. Of interest were (1) hepatocellular carcinoma, causing obstruction in three patients; (2) metastatic colonic adenocarcinoma, causing obstruction in another instance; (3) positive cytodiagnosis in a patient who developed biliary stricture following laparoscopic cholecystectomy; and (4) detection of acidfast bacilli in bile from a case of tuberculous pseudotumor mimicking a hepatic malignancy. Bile cytology is a simple, inexpensive means of obtaining tissue confirmation of neoplastic and specific inflammatory causes of biliary obstruction. It is a useful adjunct to other techniques in this era of fiberoptic diagnostic procedures. Cell block sections should be prepared whenever possible.

Adult↗
PubMedDate not supplied

Aspiration cytology of liver abscesses. With an emphasis on diagnostic pitfalls.

Clinical and imaging features of liver abscesses are not specific. Necrotic hepatic neoplasms, primary or secondary, can mimic abscesses, and vice versa. Thirty-eight patients who had cytologic confirmed abscesses were analyzed. There was clinical, radiologic and cytologic concurrence in 27 patients. In six cases the clinically suspicious lesion turned out to be inflammatory. The remaining five were malignant. There were four amebic and three tuberculous cases in this series. Cytologically, pyogenic abscesses contained a heavy, neutrophilic, inflammatory exudate with nuclear debris. By comparison, amebic cases contained more necrotic debris, with degenerating hepatocytes and fewer inflammatory cells. Acid-fast bacilli were identified in two tuberculous abscesses; however, only one contained caseous necrotic material and epithelioid cells. A potential pitfall in the cytologic diagnosis of a case of inflammatory pseudotumor is emphasized. The diagnosis of liver abscess should be established by clinical and imaging findings in conjunction with needle aspiration.

Adult↗
PubMedDate not supplied

Tuberculous pseudotumor causing biliary obstruction. Report of a case with diagnosis by fine needle aspiration biopsy and bile cytology.

Hepatobiliary tuberculosis is a rare but distinct clinical entity. We report an unusual case of biliary tract obstruction due to localized hepatic tuberculosis with periportal tuberculous adenitis. The lesion mimicked a malignancy clinically and radiologically. Fine needle aspiration biopsy revealed granulomas, epithelioid histiocytes and Langhans' giant cells. The cytodiagnosis was confirmed by identification of acid-fast bacilli in the bile cytology and isolation of Mycobacterium tuberculosis by culture. The patient responded to antituberculosis therapy. The usefulness of bile cytology in the diagnostic management of biliary tract obstruction is illustrated.

Bile↗