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Biomedical subjects

W C Chow

Publications and source records attributed to W C Chow.

At least 19 recordsLinked to original sources
PubMed2002

Prevalence of hepatitis G virus infection in patients with liver diseases in Singapore.

The prevalence of hepatitis G virus (HGV) infection in patients with liver diseases in Singapore and its pathogenic role in these patients was studied. One hundred and forty-eight patients who had chronic hepatitis or acute non A-E hepatitis were studied. Presence of HGV RNA was determined by nested polymerase chain reaction of the 5'non-coding region of the virus in all the patients. Hepatitis G IgG antibody to the envelope (E2) antigen was tested with an enzyme immunoassay (Boehringer Mannheim, Singapore) in 76 of them. Most patients (93%) were ethnically Chinese, predominantly males (74%) and chronic hepatitis B (72%) patients. Others had chronic hepatitis C (19%) or cryptogenic cirrhosis (6%). Four patients had acute non A-E hepatitis. HGV RNA and anti-HGenv were present in 3.5% and 8.3% of those with chronic liver disease. HGV infection did not account for any of the acute non A-E hepatitis and most of the cryptogenic cirrhosis.

China↗
PubMed2000

Hepatitis C: retreatment and treatment of patients with renal failure.

This paper addresses two difficult issues in the treatment of hepatitis C: patients who fail to achieve a sustained response after the first course of treatment, and those who simultaneously suffer from chronic renal failure. With the recent improvements in firstline treatment, retreatment is mainly applicable to those who have previously received 6-month of interferon monotherapy at 3 MU thrice weekly. For those who had an end-of-treatment response but relapsed, there is a choice between interferon monotherapy at increased dose and/or duration of treatment, or a 6-month course of combination therapy. Retreatment of non-responders is generally unsuccessful, but some patients may respond to interferon-alpha 3 MU and ribavirin 1.0-1.2 g/day. For patients with chronic renal failure and hepatitis C, combination treatment is not possible because ribavirin is contraindicated. Interferon given at a dose of 1.5 MU thrice weekly was reported to be fairly well tolerated by patients who were on dialysis and resulted in end-of-treatment and sustained biochemical and virological response in some cases. Interferon given in the usual doses may be associated with severe adverse effects in patients with renal failure, and can precipitate allograft rejection in patients who have undergone renal transplantation.

Antiviral Agents↗
PubMed1999

Acute myeloid leukemia relapsing as gynecomastia.

Granulocytic sarcoma (GS) is an increasingly common relapse feature of acute myeloid leukemia (AML), late in the disease course or post bone marrow transplantation (BMT). Any solid organ can be affected, and there have been a number of reports of GS in breast tissue in female patients. We present a unique case of GS in a male AML patient, presenting as painless gynecomastia immediately before BMT at advanced disease. Aberrant expression of CD56 was found in the relapsed GS tissue but not in the original AML clone. Twelve months after allogeneic BMT, leukemia relapsed again in the same breast, with normal marrow morphology and full donor chimerism. The lesion failed to respond to donor lymphocyte infusion, chemotherapy and radiotherapy, and disseminated to other subcutaneous tissues.

Adult↗
PubMed1998

Re-treatment with interferon alfa of patients with chronic hepatitis C.

Treatment of patients with chronic hepatitis C has had limited success because of relapses and nonresponse to interferon alfa therapy (currently the only established therapeutic agent). A retrospective study was done to determine the efficacy of re-treatment with interferon and the predictors of response in patients who failed to achieve sustained response after one standard course of interferon therapy (3 million units three times a week for 24 weeks). One hundred and eleven patients (47 relapsers and 64 nonresponders), mean age 45 years, were included in the study. Eighteen relapsers and 13 nonresponders received a higher dose (5 MU), and 11 relapsers and 6 nonresponders received a longer duration (48 weeks) of interferon therapy. The remaining patients received the same regimen as the first treatment. Eighty-one percent and 23% of relapsers and nonresponders, respectively, had an end-of-treatment response, and 19% and 3% of the corresponding patient groups had a sustained response to re-treatment. Two patients with breakthrough during their first treatment were the only nonresponders with sustained response after re-treatment. Sustained response was observed only in patients who received an increased dose or duration of interferon therapy. No predictor of sustained response was found. In conclusion, sustained response to re-treatment with interferon was only observed with augmentation of dose or duration of therapy in some relapsers and patients who had breakthrough. Established predictors of response to interferon in naive patients, in particular serum hepatitis C virus RNA and genotype, were not associated with sustained response to re-treatment.

Adult↗
PubMed1998

Antibodies to Ro/La, Cenp-B, and snRNPs antigens in autoimmune hepatitis of North America versus Asia: patterns of immunofluorescence, ELISA reactivities, and HLA association.

To assess whether demography is one of the important factors determining antibody response to nuclear antigens [ANA: SSA-Ro (52K and 60K), SSB-La, snRNPs (A, 70K, B'/B), and Cenp-B], we investigated 95 and 47 sera of autoimmune hepatitis (AIH) from North America and Asia, respectively, by immunofluorescent (IF) and recombinant ELISA. Correlations among nuclear IF patterns, ELISA, and disease indices were analyzed. The frequency and titer of individual antibodies differed significantly between the groups. Patients with speckled patterns were younger in both regions and had higher aspartate aminotransferase levels only in North America. HLA-A1, B8, DQ2, and DR4 or DR3 or both in North America, and A2, B61, DQ7, and DR4 in Asia were predominant. In Asia, B61 correlated with anti-70K, and DQ7 correlated with antibodies to 52K, Cenp-B, and B'/B. In North America, A1, B8, DR3 haplotype, and DQ2 correlated with antibodies to A and 70K. Anti-B'/B and DR4 in North America, and A2 in Asia, were associated with concurrent immunologic disorder. Individual ANA clusters correlated with individual HLA in the demography, and different HLA alleles might determine disease expression as well as different ANA being produced in AIH.

Adult↗
PubMed1997

Acute viral hepatitis E: clinical and serologic studies in Singapore.

Seroprevalence of hepatitis E is now documented in many countries around the world, but studies of its clinical manifestations and serologic course have been confined to endemic areas. We have prospectively evaluated the occurrence, evolution, and outcome of acute hepatitis E in our patients. Fifteen patients (11 men, 4 women; median age: 41 years) were diagnosed to have acute, sporadic hepatitis E between July 1993 and January 1995; 10 of the 15 were followed up. Sera anti-hepatitis E virus (HEV) immunoglobulin (Ig)G and IgM antibodies and HEV ribonucleic acid in the blood and stool were tested at weeks 1 and 2; serial tests for hepatitis E antibodies and liver function were carried out at months 1, 3, 6, 9, 12, and 18. Coinfection with hepatitis A and superinfection on chronic hepatitis B were found in 3 and 2 patients, respectively. One patient had transient passage of virus in the stool, but none was viremic. Eighty-seven percent of patients lost their IgM antibodies within 3 months, but anti-HEV IgG, once present, persisted throughout follow-up. All patients but one had complete recovery. A higher than reported level of alanine transaminase (mean: 28.5 times normal) and the lack of viremia during acute infection in our patients may be due to increased immune-mediated viral clearance.

Acute Disease↗
PubMed1997

Hepatitis C, E and G virus--three new viruses identified by molecular biology technique in the last decade.

The development of molecular biology techniques has enabled us to clone the genetic sequence of three new hepatitis viruses, namely, hepatitis C virus, hepatitis E virus and hepatitis G, or GBV-C virus in the last decade. Hepatitis C virus (HCV) is now known to account for the majority of the parenterally transmitted non-A, non-B hepatitis and hepatitis E virus (HEV) is the major cause of the epidemics of enterally transmitted non-A, non-B hepatitis in the less developed countries, mainly through contaminated water supplies. While 80% of those who were infected with HCV will become chronic carriers, there is no known chronic carrier state for HEV. To date, 6 major genotypes of HCV were identified, with various variants of genotype 6 described in Southeast Asia. In Singapore, the majority of our chronic hepatitis C patients are infected with genotype 1. The seroprevalence rate of HEV is 10% to 14% in Singapore. This probably reflects our suboptimal sanitary condition in the past rather than a reflection of a currently high HEV infection rate in our population. However, local cases of acute hepatitis E have been reported. As for the most recently cloned hepatitis G virus, its aetiologic role in the remaining cases of non-A, non-B hepatitis is still unclear. Some preliminary evidence suggests that it may be just an innocent bystander with limited pathogenicity and it certainly cannot account for all the remaining cases of non A-E hepatitis. Hence, the search for yet another hepatitis virus continues.

Flaviviridae↗
PubMed1996

Case report: recurrent hyperammonaemic encephalopathy due to citrullinaemia in a 52 year old man.

The present report describes a Chinese male who presented for the first time with recurrent encephalopathy and hyperammonaemia at the age of 52 years. He was found to have citrullinaemia. To our knowledge, this is the first Chinese with citrullinaemia and the first non-Japanese who has the variant form of presentation. The patient also has the longest asymptomatic period for citrullinaemia so far described. The patient's biochemical derangement, clinical features and the postulation of his late presentation are discussed. It is noteworthy that simple therapeutic measures, such as lactulose and dietary protein restriction, controlled his symptoms well.

Amino Acid Metabolism, Inborn Errors↗
PubMed1996

Hepatic manifestation of malignant histiocytosis: a case study.

Malignant histiocytosis, as defined by Rappaport, is now known as a manifestation of malignant lymphoma, the majority of which is the T-cell type. However, unlike the typical presentation of most non-Hodgkin lymphomas, this condition presents with atypical features mimicking acute hepatitis or infectious mononucleosis. The latter diagnosis is often made because of the occurrence of atypical mononuclear cells on the peripheral blood films. This is clearly seen in the seven patients we report where the initial diagnoses were that of viral fever or hepatitis. Some characteristics were found in these patients to differentiate the condition from infectious mononucleosis (IMS) and acute hepatitis (AH): paucity of lymph nodes, cholestasis and prolonged prothrombin time (PT) which is atypical IMS; persistent fever, thrombocytopaenia and disproportionately high aspartate aminotransferase which is unusual in AH in the absence of any drug or alcohol history. The PT is the most important prognosis factor. Early diagnosis and treatment led to improved survival in an otherwise aggressive and rapidly fatal condition.

Acute Disease↗
PubMed1996

Hepatitis E in Singapore--a seroprevalence study.

The seroprevalence of anti-HEV IgG was determined in a hospital-based population in a general medical unit. Patients who were otherwise well but admitted for acute, non-hepatological conditions represent the "healthy" general population, and those admitted primarily with liver disorders were studied. The seroprevalence of anti-HEV IgG was found to be 10.5% in the "healthy" population and 14.7% amongst those with liver diseases. The lack of travel history and past history of jaundice suggests presence of local cases and subclinical manifestation in some of the infected patients. There is an association between seroprevalence of hepatitis A and E, suggesting common predisposing factors for both infections. Anti-HAV IgG has a higher seroprevalence. Retesting of anti-HEV IgG in those who were initially positive found persistence of antibodies beyond twelve months. Both anti-HAV IgG and anti-HEV IgG were found more commonly in the older age groups.

Adolescent↗
PubMed1995

Inborn errors of metabolism in Singapore.

Between 1992 and 1994 the Paediatric Metabolic Centre screened 403 patients for inherited metabolic disease. Seventeen patients were diagnosed, including 7 with organic acidurias, 5 with mucopolysaccharidoses, 2 with amino acid disorders, 2 with carbohydrate disorders and 1 with hyperlipidaemia. The ethnic distribution of disorders in Singapore is compared with incidences reported by others in this part of the world. It is likely that further studies will indicate which diagnostic or screening tests would best serve this community.

Adolescent↗
PubMed1995

Immunogenicity and safety of an inactivated hepatitis A vaccine amongst Singaporeans.

The immunogenicity and reactogenicity of an inactivated hepatitis A virus (HAV) vaccine was studied in healthy Singaporean adult volunteers. One hundred and forty healthy volunteers with normal alanine (ALT) and aspartate (AST) transaminases and no previous exposure to HAV, received three 1 ml doses (720 ELISA units) of an inactivated HAV vaccine (Smithkline Beechams Biologicals) following a 0, 1, 6 months vaccination schedule. All subjects were asked to record and grade the severity of any reactions for three consecutive days after each dose. Serum ALT and AST as well as anti-HAV were measured at 0, 1, 2, 6 and 7 months after the first vaccine dose. Anti-HAV seroconversion occurred when levels rose above 40 mIU/ml. Eighty-five percent of vaccinees seroconverted after the first innoculation and 99% after the second injection. All vaccinees seroconverted after the third dose. Geometric mean anti-HAV titers (GMTs) were, respectively, 119, 391, 4406 mIU/ml one month after each of the three doses. The most common side effect was transient pain and tenderness at the vaccination site. No elevation of ALT or AST levels were noted during the study period. The inactivated hepatitis A vaccine used in this study is safe and highly immunogenic in the local adult population. Two doses one month apart appeared to give adequate protection.

Adult↗
PubMed1993

Gall bladder empyema--another good reason for early cholecystectomy.

Over an 18-month period, 31 cholecystectomies were performed for empyema of the gall bladder. Analysis of these 31 cases showed that clinical features referable to the diagnosis and seriousness of this condition were few. The presence of a gall bladder mass was detected in only 35% of patients. In adopting a policy of early cholecystectomy for patients admitted for acute gall bladder disease, a low mortality rate of 3.2% was achieved for this group of patients with empyema of the gall bladder. Based on these results, we found that empyema of the gall bladder is another good reason to support early cholecystectomy.

Adult↗
PubMed1992

Mirizzi syndrome with cholecystocholedochal fistula: preoperative diagnosis and management.

Gallstone obstruction of the cystic duct with resulting repeated attacks of inflammation and pressure necrosis leads to the formation of cholecystocholedochal fistulas (Mirizzi syndrome type II). Obstructive jaundice and cholangitis are the common presentations of the condition. These fistulas are often not recognized before operation and constitute a high risk of damage to the common duct during a formal cholecystectomy. A high index of suspicion is required to diagnose the condition. We report five patients with cholecystocholedochal fistulas diagnosed by endoscopic retrograde cholangiography that delineated the fistula and the obstructing stone. The plan of management was formulated before surgery, and persistent attempt to dissect the Calot's triangle was avoided. In three patients the common duct defect was closed with the use of a gallbladder flap. Hepaticojejunostomy was required for the two difficult cases with large common duct defects and inflamed tissue.

Aged↗