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Biomedical subjects

M J Tong

Publications and source records attributed to M J Tong.

At least 55 records · Page 3Linked to original sources
PubMed1991

Nonviral risk factors for hepatocellular carcinoma in a low-risk population, the non-Asians of Los Angeles County, California.

We conducted interviews on 74 patients with histologically confirmed hepatocellular carcinoma. These patients, aged 18-74 years, were black or white residents of Los Angeles County. We also interviewed 162 population control subjects who were comparable to the case patients by age, sex, and race. Cigarette smoking was a significant risk factor for hepatocellular carcinoma [relative risk (RR) = 2.1; 95% confidence limits (CL) = 1.1, 4.0]; the effects were similar in men and in women. Heavy alcohol consumption was another risk factor for hepatocellular carcinoma in men; men who consumed 80 g or more of ethanol per day had an RR of 4.7 (95% CL = 1.4, 15.4) relative to those who had never drunk alcohol on a weekly basis. The level of alcohol intake was relatively low in women, and no significant effect on risk of hepatocellular carcinoma was observed. Use of oral contraceptives was significantly related to risk of hepatocellular carcinoma in women (RR = 3.0; 95% CL = 1.0, 8.8); those who were exposed for more than 5 years exhibited a 5.5-fold increased risk (95% CL = 1.2, 24.8). The effects of these three risk factors on hepatocellular carcinoma development were independent of each other and independent of serologically determined viral hepatitis. Our data suggest that cigarette smoking, alcohol consumption, and use of oral contraceptives are major risk factors for hepatocellular carcinoma among non-Asian residents of Los Angeles County. We also observed a significant association between a history of diabetes and hepatocellular carcinoma (RR = 3.3; 95% CL = 1.5, 7.2), especially among those who had received insulin treatment (RR = 18.5; 95% CL = 2.2, 156.0). This association may have etiological significance.

Adolescent↗
PubMed1991

A randomised double-blind placebo-controlled trial of prednisolone therapy in HBeAg and HBV DNA positive Chinese patients with chronic active hepatitis B.

Forty-one hepatitis B e antigen (HBeAg) and hepatitis B virus (HBV) DNA positive Chinese patients with chronic active hepatitis B were randomized to receive either prednisolone or placebo oral for 8 weeks. The prednisolone group received 60 mg daily for 2 weeks, 40 mg for 2 weeks, 20 mg for 2 weeks, 10 mg for 1 week and 5 mg for 1 week. In 18 patients receiving prednisolone, serum HBV DNA levels rose during the course of therapy, but dropped abruptly within 1 month of cessation of treatment. Conversely, their serum alanine aminotransferase (ALT) levels decreased during high doses of prednisolone therapy, and then became transiently elevated during the period of withdrawal of prednisolone. At 1 year from initial treatment, the serum HBV DNA and ALT levels were similar between the groups of patients treated with prednisolone or placebo. In the prednisolone treated group, 66.7% of patients became HBV DNA negative, 50% became HBeAg negative, and 33.3% seroconverted to antibody to HBeAg (anti-HBe). In the placebo treated group, 60.9% of patients became HBV DNA negative, 60.9% became HBeAg negative, and 56.5% seroconverted to anti-HBe. Hepatic decompensation was not noted in any of the prednisolone-treated patients. Thus, the effects of the withdrawal prednisolone therapy on serum ALT and HBV DNA levels was temporary, and no differences in serum viral markers or biochemical parameters of liver inflammation between these two groups were noted at the 1 year follow-up period.

Adult↗
PubMed1990

Prevalence of hepatitis B and C viral markers in black and white patients with hepatocellular carcinoma in the United States.

The recent cloning of the genome of a non-A, non-B hepatitis agent, designated the hepatitis C virus (HCV), has led to the development of an immunoassay for circulating HCV antibodies (anti-HCV). We used this immunoassay to investigate the possible association between HCV infection and hepatocellular carcinoma in black and white residents of Los Angeles County, California. Serum samples from 51 patients (12 black and 39 white) in Los Angeles County with hepatocellular carcinoma and 128 control subjects (1 black and 127 white) were tested for the presence of anti-HCV. In addition, samples were tested for hepatitis B surface antigen (HBsAg), antibodies to the hepatitis B core antigen (anti-HBc), and antibodies to HBsAg (anti-HBs). Our results indicate that the presence of anti-HCV was a significant risk factor for hepatocellular carcinoma; the relative risk was 10.5 (95% confidence limits = 3.5, 31.3). Hepatocellular carcinoma risk was also significantly related to the presence of one or more of the hepatitis B virus (HBV) markers, primarily HBsAg and anti-HBc, and the relative risk was 7.0 (95% confidence limits = 3.1, 16.1). HCV and HBV independently contributed to hepatocellular carcinoma development. Significantly increased risk of hepatocellular carcinoma was demonstrated in individuals with HCV (relative risk = 4.8) or HBV (relative risk = 4.4) serologic markers alone. A synergistic effect on risk was observed when both hepatitis B and C viral markers were present in peripheral blood (10 cases vs. no controls). We estimate that approximately 47% of hepatocellular carcinoma occurring in black and white residents of Los Angeles County could be attributed to prior HCV and/or HBV infections: 9% were related to HCV alone, 20% to HBV alone, and 18% to occurrence of both HCV and HBV infections.

Antibodies, Viral↗
PubMed1989

Hepatitis B vaccination of neonates and children.

Perinatal transmission of the hepatitis B virus (HBV) occurs in a high percentage of infants born to mothers who are acutely infected with the virus at the time of delivery or who are chronic carriers of the hepatitis B surface antigen (HBsAg). The majority of infants who acquire the virus during the perinatal period and become HBV carriers have no clinical symptoms. However, there are reports of acute and fulminant hepatitis and even primary liver cancer occurring in a few HBsAg-positive infants. Immunoprophylaxis given to infants born to HBsAg-positive mothers at birth with a combination of hepatitis B immunoglobulin and hepatitis B vaccine is the most effective means of preventing the chronic HBV carrier state and its potential complications. In a multicenter trial in the United States, 85 to 90 percent of the children of HBsAg-positive mothers remained HBsAg-negative when treated with this combination regimen. Studies conducted outside the United States have yielded similar results. Other investigations indicate that the hepatitis B vaccine alone may be of value in preventing perinatal transmission of HBV in developing countries that are unable to afford hepatitis B immunoglobulin.

Asia↗
PubMed1989

Relationship between cell membrane potential and natural killer cell cytolysis in human hepatocellular carcinoma cells.

One of the body's natural defense mechanisms against tumor cells is lysis of the invading cell by cytotoxic T-cells and natural killer (NK) cells. Five human hepatocellular carcinoma cell lines were found to have different sensitivities to killing by peripheral blood monocytes in a 51Cr release assay. This killing was demonstrated to be due to NK cell lysis. Electrical recording measurements of the membrane potentials of these five cell lines showed different values for each line, all below values reported for normal hepatocytes. Correlation between mean cell membrane potential, and sensitivity to NK lysis, revealed an inverse relationship. In this study we demonstrate that the lower the mean membrane potential of a human hepatocellular carcinoma cell line, the more sensitive it is to NK cell cytolysis. Cell surface positive potential did not correlate with NK cytolysis and only a weak correlation was found between cell membrane negative potential and cell surface positive potential between cell lines.

Carcinoma, Hepatocellular↗
PubMed1989

Hepatitis B virus, aflatoxins, and hepatocellular carcinoma in southern Guangxi, China.

We examined the roles of the hepatitis B virus and aflatoxin B1 in the development of primary hepatocellular carcinoma (PHC) in a cohort of 7917 men aged 25 to 64 yr old in southern Guangxi, China, where the incidence of PHC is among the highest in the world. After accumulating 30,188 man-yr of observation, 149 deaths were observed, 76 (51%) of which were due to PHC. Ninety-one% (69 of 76) of PHC deaths were hepatitis B surface antigen (HBsAg) positive at enrollment into the study in contrast to 23% of all members of the cohort (RR = 38.6). Three of the four patients who died of liver cirrhosis also were HBsAg positive at enrollment. There was no association between HBsAg positivity state and other causes of death. Within the cohort, there was a 3.5-fold difference in PHC mortality by place of residence. When estimated aflatoxin B1 levels in the subpopulations were plotted against the corresponding mortality rates of PHC, a positive and almost perfectly linear relationship was observed. On the other hand, no significant association was observed when the prevalence of HBsAg positivity in the subpopulations was compared with their corresponding rates of PHC mortality.

Adolescent↗
PubMed1988

A cost comparison analysis for screening and vaccination of hospital personnel with high- and low-prevalence hepatitis B virus antibodies in California.

We compared the cost of antibody screening and the projected cost for hepatitis B vaccination of antibody-negative individuals at hospitals with "high prevalence" and "low prevalence" rates for hepatitis B virus antibodies among their employees. The use of hepatitis B core antibody for screening and subsequent hepatitis B vaccination of antibody-negative personnel was most cost-effective for hospitals considered to have high prevalence for hepatitis B virus antibodies among its staff, although use of hepatitis B surface antibody in this setting only increased costs by 1.4%. In a hospital with low prevalence for hepatitis B virus antibodies among its staff, use of hepatitis B surface antibody and subsequent vaccination of antibody-negative individuals was the most cost-effective approach, while use of hepatitis B core antibody for the above purposes would have increased costs by 3.4%. The use of both hepatitis B surface antibody and core antibody in either setting followed by immunization was least economical, as costs were increased by 13% and 13.5% respectively. We concluded that hepatitis B core antibody should be used for screening in hospitals with high prevalence for hepatitis B virus antibodies among employees while hepatitis B surface antibody be used for screening in hospitals with low prevalence for hepatitis B virus antibodies among employees. A prediction of high and low prevalence for hepatitis B virus antibodies in hospital personnel may be made by knowledge of the distribution in ethnicity of staff.

Adolescent↗
PubMed1987

Intrahepatic, nucleocapsid antigen-specific T cells in chronic active hepatitis B.

Hepatitis B core antigen (HBcAg)-specific T cell lines were established from hepatic lymphomononuclear cells derived from five patients with chronic active hepatitis B. No hepatitis B virus envelope antigen-specific cell lines were established. Proliferation in response to recombinant and native HBcAg, but not to native hepatitis B surface antigen containing the pre-S(2) region, confirmed the specificity of the five T cell lines. All cell lines represented mixed populations of CD4+ and CD8+ T cells. The CD4+ subset provided antigen-specific help to autologous B cells with respect to anti-HBc production and to CD8+ cells with regard to HBcAg-induced proliferation and suppressor activity. The CD8+ subset contained suppressor cells that selectively inhibited the proliferative response of autologous HBcAg-specific CD4+ cells without inhibiting CD4+ cells of unrelated specificity (tetanus toxoid). Moreover, the CD8+ cells were also capable of suppressing HBcAg-stimulated antibody to HBcAg production without showing inhibition of total immunoglobulin production stimulated by pokeweed mitogen. The cytotoxic potential of the T cell lines was established in a lectin-dependent cytotoxicity system; natural killer cytotoxicity was completely absent. Our data suggest that the lesional T cells present at the site of hepatocellular injury in chronic active hepatitis B are primarily HBcAg-specific lymphocytes of the helper and suppressor/cytotoxic phenotypes and that both are functionally competent.

Antibody Formation↗
PubMed1987

Yeast-recombinant hepatitis B vaccine. Efficacy with hepatitis B immune globulin in prevention of perinatal hepatitis B virus transmission.

A yeast-recombinant hepatitis B vaccine was licensed recently by the Food and Drug Administration and is now available. To assess the efficacy of the yeast-recombinant vaccine, we administered the vaccine in combination with hepatitis B immune globulin to high-risk newborns. If infants whose mothers were positive for both hepatitis B surface antigen and the e antigen receive no immunoprophylaxis, 70% to 90% become infected with the virus, and almost all become chronic carriers. Among infants in this study who received hepatitis B immune globulin at birth and three 5-micrograms doses of yeast-recombinant hepatitis B vaccine, only 4.8% became chronic carriers, a better than 90% level of protection and a rate that is comparable with that seen with immune globulin and plasma-derived hepatitis B vaccine. These data suggest that, in this high-risk setting, the yeast-recombinant vaccine is as effective as the plasma-derived vaccine in preventing hepatitis B virus infection and the chronic carrier state.

Carrier State↗
PubMed1987

Vibrio vulnificus infection after raw oyster ingestion in a patient with liver disease and acquired immune deficiency syndrome-related complex.

Sepsis, peritonitis, and gastroenteritis developed in a 45-yr-old homosexual man 1 day after ingestion of raw oysters. The patient had chronic active hepatitis and cirrhosis with hepatitis B virus and delta-infection. He also had persistent generalized lymphadenopathy associated with HTLV-III antibody positivity. Vibrio vulnificus was isolated from the patient's blood and peritoneal fluid as well as from the same batch of oysters at the restaurant where the patient had visited. To our knowledge, this is the first report relating direct microbiologic and clinical evidence that the infection is acquired through the gastrointestinal tract by consuming raw seafood containing the pathogen. This is also the first reported case of peritonitis associated with sepsis and gastroenteritis from this organism. Patients with liver disease and other immunocompromised states should be warned about such life-threatening infections and complications associated with the consumption of raw oysters or other undercooked seafoods.

AIDS-Related Complex↗
PubMed1987

Persistence of serum hepatitis B virus deoxyribonucleic acid in hepatitis B surface antigen-positive patients with chronic persistent hepatitis treated with prednisone.

The effect of a short course of prednisone therapy was evaluated in 8 patients with liver biopsy-verified chronic persistent hepatitis B. In 6 of the 8 (75%) patients, an abrupt fall in serum alanine aminotransferase levels after the initiation of prednisone was noted, and in 4 patients, there was an increase in serum alanine aminotransferase values after prednisone was discontinued. However, the serum levels of hepatitis B virus deoxyribonucleic acid were consistently greater than or equal to 200 pg before, during, and after the course of treatment in 7 of the 8 (87.5%) patients. All patients were initially hepatitis B e antigen-positive and remained so during the study period. These findings indicate that, unlike some patients with chronic active hepatitis B, immunosuppression with prednisone had no effect in altering hepatitis B viral replication in patients with chronic persistent hepatitis.

Adult↗
PubMed1987

The application of flow cytometry in the study of natural killer cell cytotoxicity.

A flow cytometric assay was developed to detect the cytotoxic function of natural killer (NK) cells. This procedure employed a single fluorochrome and forward angle light scatter to differentiate dead cells from live cells. When results obtained by flow cytometry were compared with 51Cr release assay, this assay showed high specificity and sensitivity. When propidium iodide was used to stain target cells killed by NK cells, we found that NK cell cytotoxicity was not cell cycle specific.

Cell Survival↗
PubMed1987

A hepatitis B vaccination program in a community teaching hospital.

Prior to offering the hepatitis B (HB) vaccine, a prescreen for hepatitis B virus (HBV) antibodies was conducted in a 565 bed hospital in Pasadena, California. Antibodies to the hepatitis B virus were detected in 14.5% of 1,745 employees tested. There was a significantly higher prevalence in those with a previous history of hepatitis, blood transfusions, exposure to needlesticks, number of years in the same occupation, and in the same hospital work area. Employees of Asian extraction (33.3%) and blacks (23.1%) had a higher prevalence of antibodies to the hepatitis B virus than Hispanics (13.7%) and whites (10.2%). Anti-HBs was detected in 92.6% of 865 employees who received three doses of the hepatitis B vaccine. Only 28.6% of nonresponders receiving a fourth dose of hepatitis B vaccine produced anti-HBs. The nonresponders to the HB vaccine were older (average age 64.9 years) when compared to the responders (average age 37.5 years), and more males failed to produce anti-HBs after vaccination than females. Hepatitis B vaccination of the majority of individuals with either "low level" anti-HBs alone or anti-HBc alone did not elicit an anamnestic response after one dose of vaccine, implying that these "low level" antibodies are nonspecific and do not represent antiviral antibodies. Adverse reactions to the hepatitis B vaccine were minor and included a flu-like syndrome, sore arm, and rash and swelling at the injection site. The reasons for nonparticipation were obtained from 179 individuals, and the main issue was concern about safety of the hepatitis B vaccine.

Adult↗
PubMed1987

Pulmonary involvement in primary biliary cirrhosis.

Four patients with primary biliary cirrhosis (PBC) and Sjogren's syndrome presented with pulmonary disease manifested by fever, cough, and dyspnea. One patient had obstructive lung disease secondary to an autoimmune process documented by immunofluorescent staining of lung parenchyma. The other three patients had interstitial lung disease, pulmonary nodules, and multiple granulomas of the lung, respectively. Primary biliary cirrhosis is a complex autoimmune syndrome involving a disorder of the secretory immune system and its epithelial end organs. These four cases suggest that, in addition to biliary, lacrimal, intestinal, renal tubular, and salivary epithelium, lung tissue also is a possible site for autoimmune involvement in PBC.

Adult↗
PubMed1987

Correlation between hepatic hepatitis B core antigen and serum hepatitis B virus-DNA levels in patients with chronic hepatitis B virus infections in Taiwan.

Paired liver biopsy specimens and serum samples from 76 patients with chronic hepatitis B virus (HBV) infection were taken for staining of hepatitis B core antigen (HBcAg) by immunoperoxidase and testing of HBV-DNA by a spot hybridization technique, respectively. Thirty-two tissue specimens showed positive staining for HBcAg in their hepatocytes. The two patients with diffuse HBcAg expression in liver tissue also had high serum concentrations of HBV-DNA (greater than 10 pg/10 microL). Among 30 patients with focal HBcAg distribution, 28 patients (93.3%) had measurable levels of serum HBV-DNA and 17 patients (60.7%) had high levels of serum HBV-DNA. Of 44 patients without hepatic HBcAg expression, only 12 patients (27.3%) had detectable serum HBV-DNA, and most patients (93.1% [11/12]) had low concentrations (less than 10 pg/10 microL). Nineteen patients had superimposed hepatitis D virus infection, and, of these, three patients (15.8%) had detectable serum HBV-DNA in low concentrations, while one of the three patients had stainable HBcAg in his hepatocytes with focal distribution. Two of the three patients with hepatitis A virus superinfection who had focal HBcAg expression in their liver tissue had serum HBV-DNA levels that were high during the acute phase of hepatitis A virus infection, and in one patient his serum HBV-DNA levels further increased from 10 pg/10 microL to 40 pg/10 microL during the recovery phase. Thus, measurement of serum HBV-DNA levels in patients with chronic HBV infection correlated well with their hepatic HBcAg expression, and both represent the precise status of HBV replication.

Adolescent↗