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Biomedical subjects

S K Lam

Publications and source records attributed to S K Lam.

At least 163 records · Page 9Linked to original sources
PubMed1998

Histological changes of concurrent hepatitis C virus infection in asymptomatic hepatitis B virus patients.

In chimpanzees and in vitro cell culture studies, hepatitis C infection has been shown to suppress hepatitis B virus expression. In addition, hepatitis C infection can cause much more severe liver disease in patients chronically infected with hepatitis B virus. The aims of the present study were to determine the prevalence of hepatitis C infection in asymptomatic chronic hepatitis B Hong Kong Chinese patients and the histological changes and hepatic expression of hepatitis B virus and hepatitis C virus. Five hundred and seventy-one Hong Kong Chinese asymptomatic chronic hepatitis B patients were studied. Only four (0.7%) were hepatitis C virus antibody positive; they were also all positive for hepatitis C viral RNA in serum by reverse transcription-polymerase chain reaction (RT-PCR). Portal lymphoid aggregates and bile duct damage was noted in the liver sections of three of the four patients. Hepatic expression of hepatitis B surface antigen was detected in three patients; none had detectable hepatitis B core antigen. By branched DNA assay, serum hepatitis B DNA could not be detected in any of the four patients, but three had hepatitis C RNA. By in situ RT-PCR, hepatitis C RNA was detected in the cytoplasm of three of the four patients. These findings suggest that hepatitis C coinfection in asymptomatic chronic hepatitis B patients is uncommon in Hong Kong Chinese and active hepatitis B viral replication is absent in these patients.

Adolescent↗
PubMed1998

Differential north to south gastric cancer-duodenal ulcer gradient in China. China Ulcer Study Group.

There are suggestions that duodenal ulcer protects individuals from gastric cancer and that rice is ulcerogenic while wheat is gastro-protective. We aimed to examine the relationship of gastric cancer, duodenal and gastric ulcers in different geographical regions in China and identified dietary risk factors for duodenal ulcer and gastric cancer. The prevalence of peptic ulcer and gastric cancer among symptomatic patients in eight major cities, four each from the north and the south representing all the six defined regions of China were studied. Endoscopy and case records over a 10 year period were reviewed and cases of confirmed duodenal and gastric ulcer and gastric cancer, together with the total number of endoscopies performed per year, were recorded. Rates were expressed as cases/1000 endoscopies. Results were compared to another epidemiological study on diet and mortality in the same regions in China conducted at the same time. Duodenal ulcer rates were 2.4-fold higher in southern China than northern China, whereas gastric cancer rates were 1.6-fold higher in the north than in the south. Correlation studies showed for the first time an inverse linear relationship between the gastric cancer rates and the duodenal ulcer rates (r=-0.8076, P=0.015), as well as the duodenal ulcer: gastric ulcer ratios (r=-0.9133, P=0.002). Gastric ulcer rates were higher in southern China but did not correlate with the gastric cancer rates (r=0.1455, P=0.731). Duodenal ulcer rates were found to be related to daily rice intake (r=0.8554, P=0.029) and inversely related to daily wheat flour intake (r=-0.8472, P=0.033). Gastric cancer rates were not related to any dietary risk factors tested. We concluded there was an inverse relationship between gastric cancer rates and duodenal ulcer rates. Although duodenal ulceration and gastric cancer are both linked to Helicobacter pylori infection, the findings of this study indicate independent additional aetiological factors for the pathogenesis of these conditions. Dietary factors such as rice or wheat intake may play a role.

Adult↗
PubMed1998

Management guidelines for uninvestigated and functional dyspepsia in the Asia-Pacific region: First Asian Pacific Working Party on Functional Dyspepsia.

Dyspepsia is most optimally defined as pain or discomfort centred in the upper abdomen. The symptom complex may be caused by peptic ulcer disease, gastro-oesophageal reflux, or gastric cancer but is most often due to functional (or non-ulcer) dyspepsia. While upper endoscopy is the method of choice to determine the underlying cause of dyspepsia, it is expensive. A more pragmatic approach is needed in the Asia Pacific region where health services are limited. A detailed treatment algorithm is given for managing patients presenting with new-onset dyspepsia and documented functional dyspepsia after endoscopy, and evidence to support this approach is reviewed. Prompt endoscopy is recommended for patients with alarm features. In patients without alarm features, treatment for 2-4 weeks with an empirical anti-secretory or prokinetic agent, followed by investigation using non-invasive Helicobacter pylori testing and treatment for patients who do not respond or relapse, is recommended. Trials of management strategies are now needed to establish the efficacy and cost-effectiveness of the approaches recommended.

Antiemetics↗
PubMed1998

High seroprevalence of Helicobacter pylori in active bronchiectasis.

Helicobacter pylori causes chronic inflammation of the gastric mucosa and has been identified in tracheobronchial secretions. Serum IgG against H. pylori was therefore measured prospectively in consecutive subjects with bronchiectasis (n = 100; mean age +/- SD 55.1 +/- 16.7 yr), active pulmonary tuberculosis (n = 87; age, 57.3 +/- 19.1 yr), and healthy volunteers (n = 94; age, 54.6 +/- 7.6 yr). Seropositivity was found in 76.0% of bronchiectatic subjects, which was significantly higher than that of the control (54.3%, p = 0.001) and tuberculous (52.9%, p = 0.0001) groups. Multiple logistic regression, adjusted for age, sex, occupational social class, and number of persons living in the household, showed that H. pylori IgG levels of the bronchiectatic group were still significantly higher than that of the control (p = 0.0014) and tuberculous (p = 0.0154) groups. Multiple regression analysis revealed associations between H. pylori serology and sputum volume (p = 0.03) and age (p = 0.001) in the bronchiectatic patients, but not lung function indices or causes of bronchiectasis. The H. pylori seroprevalence in bronchiectasis was significantly (p = 0.0002) higher in patients who produced more (83.1%) than those who produced less than 5 ml sputum/24 h (58.6%). This is the first report of a high H. pylori seroprevalence in bronchiectasis which appears to be specific. Further studies are indicated to evaluate the possible pathogenic role of H. pylori in bronchiectasis.

Age Factors↗
PubMed1998

Cellular proteins bind to the 3' and 5' untranslated regions of dengue 2 virus genome.

In vitro generated cloned full length dengue 2 virus untranslated regions (UTRs) were used in RNA gel mobility shift assays to examine cellular factors binding to the virus genomes. Cellular factors in lysates of Vero (monkey) and C6/36 (mosquito) cells bound specifically and non-specifically to the dengue 2 virus 3' UTR. Non-specific interaction with the 5' UTR, resulting in formation of at least 4 band shift complexes was noted with lysate of the C6/36 cells only. Pre-treating the cell lysates with proteinase K affected binding of cellular factors to the dengue 2 virus UTRs, suggesting that the cellular factors were proteins. These findings suggest that cellular proteins could interact with specific sites on the dengue virus genomes.

3' Untranslated Regions↗
PubMed1998

Isolation and identification of human herpesvirus 7 from an infant with exanthem subitum.

Exanthem subitum (ES) is a common childhood exanthematous disease. In a recent study of ES due to human herpesvirus 6 (HHV 6), we isolated human herpesvirus 7 (HHV 7) from the peripheral blood mononuclear cells (PBMC) of a seven month-old infant with typical symptoms of ES. The identity of the virus was confirmed by indirect immunofluorescence using HHV 7 specific monoclonal antibody and by amplification of the HHV 7 specific genomic sequences using the polymerase chain reaction (PCR). Paired serum samples from the infant showed serological conversion to the isolated virus. The clinical manifestations of ES in this infant appeared to be milder than the classical ES due to HHV 6.

Antibodies, Monoclonal↗
PubMed1997

Helicobacter pylori induces interleukin-8 expression in endothelial cells and the signal pathway is protein tyrosine kinase dependent.

Helicobacter pylori (HP) infection has been shown to increase gastric mucosal interleukin 8 (IL-8) expression, and whether HP or its toxin induces endothelial cell IL-8 expression is unknown. We aimed to compare the IL-8 expression in endothelial cells after stimulation with HP toxin, tumor necrosis factor alpha (TNF-alpha), and lipopolysaccharide (LPS) and to study their signal pathways. HP or its toxin induced significant IL-8 expression in endothelial cells. HP toxin, TNF-alpha, and LPS also showed a time- and dose-dependent increase in IL-8 expression over the control. Both protein kinase C (PKC) and protein kinase A (PKA) inhibitors had no effect on IL-8 response to these stimuli. Protein tyrosine kinase (PTK) inhibitor genistein at concentrations of 150, 300, and 450 microM dose-dependently reduced LPS- and TNF-alpha-induced IL-8 expression by 29.43, 43.8, and 47.3% and 20.5, 49.9, and 61.8% respectively, whereas HP toxin-induced IL-8 secretion could only be reduced at 450 microM by 35.7%. Geldanamycin, a more potent PTK inhibitor, at doses of 0.5, 1, and 2 microM dose-dependently reduced HP toxin induced endothelial cell IL-8 expression by 24.8, 26, and 44.3% respectively. It is concluded that HP and its toxin can increase IL-8 expression in endothelial cells, and the expression of IL-8 elicited by HP toxin, TNF-alpha, and LPS is partially dependent on PTK but not PKA or PKC activation.

Bacterial Proteins↗
PubMed1997

Clearance of hepatitis B surface antigen after bone marrow transplantation: role of adoptive immunity transfer.

Adoptive immunity transfer has been reported to be effective in clearing chronic hepatitis B virus (HBV) infection. Two hundred twenty-six patients who received allogeneic bone marrow transplantation (BMT) between May 1990 and September 1995 were screened for hepatitis B markers. Twenty-one patients were hepatitis B surface antigen (HBsAg) positive before BMT. The median follow-up period was 20 months (range, 2-59 months). Two of these patients had sustained clearance of HBV infection after transplantation. Both patients were hepatitis B e antigen (HBeAg)-negative, hepatitis B e antibody (anti-HBe)-positive, and serum HBV DNA-negative (by dot-blot hybridization) before BMT. Both had a flare in the serum alanine transaminase (ALT) level around the time of HBsAg clearance. Sustained clearance of HBsAg was observed in 2 of the 5 patients who received hepatitis B surface antibody (anti-HBs)-positive marrow but in none of the 16 patients who received anti-HBs-negative marrow (P < .05). One additional patient who received anti-HBs-positive marrow had transient HBsAg seroconversion. Among the 18 patients who remained persistently HBsAg-positive after BMT, 3 had HBeAg seroconversion and 3 had reversion to HBeAg positivity. In this study, we found a significant association between clearance of HBV infection and anti-HBs-positive bone marrow donors. Adoptive immunity transfer is effective in clearing HBV from patients with chronic HBV infection.

Adolescent↗
PubMed1997

A retrospective and prospective study on the safety of discharging selected patients with duodenal ulcer bleeding on the same day as endoscopy.

BACKGROUND: Low risk of rebleeding has been observed in patients with gastrointestinal bleeding due to peptic ulcer without high-risk stigmata of recent hemorrhage. We aimed to evaluate the safety and acceptability of an aggressive early discharge policy in those patients admitted with upper gastrointestinal bleeding due to duodenal ulcers without high-risk stigmata of recent hemorrhage. METHOD: Retrospective analysis was carried out in bleeding ulcer patients less than 60 years of age with stable vital signs and no stigmata or only flat spots on endoscopy. A prospective study was then performed that included only duodenal ulcer patients less than 60 years of age with stable vital signs, no concomitant serious medical illness, and no stigmata of recent hemorrhage. These patients were discharged on the same day that endoscopy was performed. RESULTS: During a period of 18 months, 72 patients satisfied the criteria in the retrospective study. The mean hospital stay was 1.4 days (range, 1 to 5). There were no episodes of rebleeding nor significant drops in hemoglobin level 2 weeks after discharge (10.8 gm/dL +/- 1.4 vs 11.0 gm/dL +/- 1.5). Seventy-five patients were recruited into the prospective study. None of them had rebleeding nor significant drops in hemoglobin 1 week after discharge (12.1 gm/dL +/- 1.8 vs 11.7 gm/dL +/- 2.5). CONCLUSION: We conclude that patients with gastrointestinal bleeding who have clean-based duodenal ulcers and are stable on admission can be safely discharged on the same day as endoscopy.

Adolescent↗
PubMed1997

Hepatic events after bone marrow transplantation in patients with hepatitis B infection: a case controlled study.

Hepatitis B reactivation following chemotherapy withdrawal may result in hepatitis, hepatic failure and death. We studied the clinical outcome and the causes of hepatic events of hepatitis B surface antigen positive recipients undergoing bone marrow transplantation. Twenty-four hepatitis B surface antigen patients were matched with 24 hepatitis B surface antigen negative patients for age, sex, CMV positive serology, underlying hematological disease and type of bone marrow transplantation. Post-BMT, there were 18 patients in the hepatitis B surface antigen positive group and four patients in the hepatitis B surface antigen negative group who suffered from hepatitis (P < 0.05). Thirteen of the 18 hepatitis were related to HBV reactivation in the hepatitis B surface antigen positive group and none of the four hepatitis in the hepatitis B surface antigen negative group (P = 0.01). The hepatitis B surface antigen positive group also had an increased incidence of acute graft-versus-host disease of liver (6 vs 1, P = 0.03). However, there was no significant increase in the incidence of veno-occlusive disease (10 vs 7, P = 0.40) and persistent hepatitis (3 vs 0, P = 0.07) in the hepatitis B surface antigen positive group. Using the log-rank test, there was no significant difference in survival between the hepatitis B surface antigen positive and negative recipients.

Adult↗
PubMed1997

The vascular and glandular organoprotective properties of metronidazole in the rodent stomach.

BACKGROUND: The gastroprotective action of metronidazole, an antimicrobial used in the therapy against Helicobacter pylori infection, is unclear. Thus, the aim of the present investigation was to study the organoprotective action and antiulcer mechanisms of this drug in rodents. METHODS AND RESULTS: Metronidazole (10 mg/kg), given either per os or intraperitoneally, 30 min beforehand, reduced ethanol (40%, 10 mL/kg, p.o.)-induced gastric mucosal damage in male rats. Likewise, oral administration of metronidazole dose-dependently attenuated the indomethacin (30 mg/kg, p.o.)-induced gastric lesion formation and the concurrent depletion of mucosal mucus. However, metronidazole did not affect the basal mucosal prostaglandin E2 content. In an ex vivo gastric chamber preparation, 40% ethanol incubation markedly lowered transmucosal potential difference and increased mucosal vascular permeability in rat stomachs. Incubation with all doses of metronidazole did not modulate gastric mucosal blood flow nor transmucosal potential difference, either before or after ethanol treatment. Nevertheless, the increase in vascular permeability by 40% ethanol was significantly alleviated by either p.o. or i.p. metronidazole pretreatment. In addition, exposure of the isolated rabbit gastric gland preparation to metronidazole (10(-5) and 10(-4) M) significantly attenuated the damaging action of 10% ethanol. CONCLUSION: It is concluded that metronidazole possesses a direct vascular and glandular organoprotective property in the rodent stomach. However, the anti-ulcer action does not appear to involve prostaglandins nor act through the improvement of gastric mucosal blood flow. Preservation of intramucosal mucus may partly contribute to the prevention of indomethacin-induced ulceration in rats.

Animals↗
PubMed1997

Vertical transmission of dengue.

Dengue, an important mosquito-borne flavivirus infection, is endemic in Southeast Asia. We describe two mothers who had acute dengue 4 and 8 days before the births of their infants. One mother had worsening of her proteinuric pregnancy-induced hypertension, liver dysfunction, and coagulopathy and required multiple transfusions of whole blood, platelets, and fresh frozen plasma. Her male infant was ill at birth, developed respiratory distress and a large uncontrollable left intracerebral hemorrhage, and died of multiorgan failure on day 6 of life. Dengue virus type 2 was isolated from the infant's blood, and IgM antibody specific to dengue virus was detected in the mother's blood. The second mother had a milder clinical course; she gave birth to a female infant who was thrombocytopenic at birth and had an uneventful hospitalization. Dengue virus type 2 was recovered from the mother's blood, and IgM antibody specific to dengue virus was detected in the infant's blood. This report highlights not only the apparently rare occurrence of vertical transmission of dengue virus in humans but also the potential risk of death for infected neonates.

Acute Disease↗
PubMed1997

Can misoprostol and omeprazole reduce nicotine and ethanol induced gastric mucosal injury? A quantitative macroscopic and microscopic analysis in rats.

We compared the effects of misoprostol, omeprazole and methylcellulose (control) on gastric mucosal injury induced by nicotine and/or ethanol. The results demonstrate that misoprostol and omeprazole each significantly reduce macroscopic injury and deep injury at a microscopic level (P < 0.05) induced by nicotine alone, ethanol alone or a combination of ethanol and nicotine. Misoprostol and omeprazole each reduced the leakage of fluorescein isothiocyanate-albumin into the interstitium in the gastric mucosa. Misoprostol and omeprazole are each effective in preventing injury induced by nicotine and ethanol and vascular factors are involved.

Animals↗
PubMed1997

Does treatment of Helicobacter pylori with antibiotics alone heal duodenal ulcer? A randomised double blind placebo controlled study.

BACKGROUND: Treatment of Helicobacter pylori infection prevents duodenal ulcer relapse. It has not been established if treatment of the infection heals duodenal ulcer. AIM: To test the hypothesis that treatment of the infection was associated with healing of duodenal ulcer. METHODS: A randomised, double blind placebo controlled trial was performed to study the efficacy of an antibiotic only regimen consisting of 300 mg metronidazole, 500 mg amoxycillin, and 250 mg clarithromycin, each given four times daily for two weeks, in the healing of duodenal ulcer as assessed by endoscopy. Symptoms were controlled with acetaminophen and antacids. RESULTS: Of 100 consecutive patients with endoscopically established duodenal ulcer, 97 with positive rapid urease test on antral biopsy specimens were admitted into the study and 81 completed the trial. Of these, 40 were randomised to receive antibiotics and 41 to receive placebo. Treatment with antibiotics resulted in 92.5% (95% confidence interval (95% CI) 84.3-100) healing at four weeks and 100% at eight and 12 weeks; the corresponding healing rates for placebo treatment were respectively, 36.6%, 61%, and 63.4% (95% CIs 21.8-51.3, 46.0-75.9, and 48.7-78.2 respectively). The differences between the two treatment groups were significant at p < 0.001 at each time point and by life table analysis. Clearance of H pylori as assessed by urease test on antral biopsy specimens at four weeks and eradication of the organism as determined by 13C-urea breath test at eight weeks were achieved in 85% and 62.5% of patients respectively. Duodenal ulcer healed at four weeks in 87.2% and 86.2% (95% CIs 76.7-97.7 and 73.7-98.8) of patients in whom H pylori clearance or eradication, was achieved, versus 42.9% and 51.9% (95% CIs 27.9-57.8 and 38.3-65.5; p < 0.001 and < 0.003 respectively) in whom these processes failed. Stepwise discriminant analysis on 32 clinical, personal, and endoscopic characteristics as well as H pylori clearance and eradication identified H pylori clearance as the most discriminative variable for the healing of duodenal ulcer at four weeks, followed by ulcer depth and eradication of the organism. CONCLUSIONS: Treatment with an antibiotic only regimen was effective for the healing of duodenal ulcer, and clearance as well as eradication of H pylori contributed significantly to the healing. The results constituted the strongest evidence to date that H pylori infection was aetiologically related to duodenal ulceration, and support the concept of treating duodenal ulcer associated with H pylori as an infection and relieving its symptoms with acid reducing agents such as antacids.

Adult↗
PubMed1997

c-fos overexpression is associated with the pathoneogenesis of invasive cervical cancer.

The molecular genetics of human cervical cancer remains to be defined to a significant extent. The current study examined the prevalence and significance of proto-oncogene c-fos overexpression in cervical cancer. Immunohistochemical staining of c-fos oncoprotein was performed in 27 invasive cervical carcinomas and 30 cervical intraepithelial neoplasias (CINs) managed in our department. Eight normal cervical specimens were used as controls. In the patients with invasive cervical cancer, 8 were stage I, 12 were stage II, and 7 had stage III-IV disease. Three of the cancers were well differentiated, 18 were moderately differentiated and 6 were poorly differentiated. Twenty invasive cervical carcinomas (59%) and 3 CIN (10%) showed overexpression of c-fos. The difference is statistically significant (p < 0.001). No statistically significant relationship was found between c-fos overexpression and clinical stage, histological grade, or survival in invasive cervical cancer. In this population, c-fos overexpression appears to be common in invasive cervical cancer and correlated with the ability of the tumor to become invasive, but is not associated with the progression of cervical cancer.

Female↗
PubMed1997

Second malignant neoplasms: an increasingly recognized complication of childhood cancer.

Second malignant neoplasms (SMN) are an increasingly recognized late complication seen in childhood cancer survivors. A total of 3 cases of SMN have been found in the Department of Paediatrics, University Hospital Kuala Lumpur after a 15-year experience of treating childhood malignancies. Two cases are described here. The first developed abdominal non-Hodgkin's lymphoma 3 years after undergoing an allogeneic bone marrow transplant for second relapse of acute lymphoblastic leukaemia, while the second child developed myeloid leukaemia two years after completing treatment for acute lymphoblastic leukaemia. Progress in the management of childhood cancer in Malaysia and the availability of bone marrow transplantation facilities have increased the number of childhood cancer survivors; leading to increased incidence of SMN.

Adolescent↗
PubMed1997

The incidence of human herpesvirus 6 infection in children with febrile convulsion admitted to the University Hospital, Kuala Lumpur.

From October 1996 to March 1997, 31 children with febrile convulsions were admitted to the University Hospital, Kuala Lumpur. Human Herpesvirus 6 (HHV 6) was virologically and/or serologically confirmed to be the cause of the febrile episode in 5 of these children (16.1%). Age, sex and other associated clinical features (diarrhoea, cough, running nose and type of seizure) were not useful in differentiating cases of febrile convulsion due to HHV 6 from those of other aetiology. However, uvulo-palatoglossal junctional ulcers were noted in children in whom the cause of the seizure could be attributed to HHV 6 but not in the remaining cases in the study group. HHV 6 DNA was detected in peripheral blood mononuclear cells from all patients with febrile convulsions attributed to HHV6, and in patients shown serologically to have already been exposed to the virus by nested polymerase chain reaction amplification. Only genotype HHV 6B was detected from patients with seizure due to HHV 6 but both genotype 6A and 6B were detected in the remaining cases studied.

Child, Preschool↗