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Biomedical subjects

M H Chang

Publications and source records attributed to M H Chang.

At least 55 records · Page 3Linked to original sources
PubMed1999

Changes of hepatitis B surface antigen variants in carrier children before and after universal vaccination in Taiwan.

Mutants of a determinant of hepatitis B surface antigen (HBsAg) identified in vaccinated children pose a potential threat to long-term success of vaccination programs. We examined the mutants of a determinant (residues 110-160) of HBsAg in hepatitis B virus (HBV) DNA-positive children identified during previous serosurveys in Taipei undertaken just before (1984), 5 years after (1989), and 10 years after (1994) universal vaccination began. In HBV DNA-positive children from 3 surveys, the prevalence of a determinant mutants increased from 8 of 103 (7.8%) in 1984 to 10 of 51(19.6%) in 1989 and 9 of 32 (28.1%) in 1994 and was higher in those fully-vaccinated than unvaccinated (12/33 vs. 15/153, P =. 0003). Most amino acid changes of the variants clustered in residues 125-129 and 140-149. In all 27 children with detectable mutants, the mean age of those vaccinated was younger than those unvaccinated (4. 8 +/- 3.8 vs. 7.9 +/- 2.3 yrs, P <.05); and mutations occurred in a region with greatest local hydrophilicity (residues 140-149) more frequently in those vaccinated than in those unvaccinated (10/12 vs. 6/15, P =.0253). More mutated residues and more mutations at neutralizing epitopes, such as N146, C147, T148, and C149, were found in the 1994 survey. Vaccinated children may contract variant infections through vertical or horizontal transmission. Universal vaccination has accelerated an accumulation of HBsAg a determinant mutants with amino acid changes critical for immune escape in vaccinated children who became carriers, suggesting that new vaccination strategies should be considered.

Carrier State↗
PubMed1999

Hepatitis A vaccine in healthy adults: a comparison of immunogenicity and reactogenicity between two- and three-dose regimens.

Inactivated hepatitis A virus (HAV) vaccine was administered to 55 healthy seronegative adult volunteers to evaluate the immunogenicity and adverse reactions of two doses of HAV vaccination (25 units) in comparison with a three-dose regimen. The volunteers were randomly assigned to receive one of the two regimens: 26 were vaccinated with two doses at 0 and 24 weeks (Group 1), and 29 were vaccinated with three doses at 0, 2, and 24 weeks (Group 2). The vaccine was well tolerated and there was no serious adverse reaction. In both groups, the seroconversion rate was 100% at week 28. At week 52, all remained positive for anti-HAV regardless of a two- or three-dose regimen. No statistically significant difference in seroconversion rates and geometric mean titers could be demonstrated between the two groups. Thus, the two-dose regimen may be favorable to save cost and time for active immunization against hepatitis A.

Adult↗
PubMed1999

Prospects for hepatitis B virus eradication and control of hepatocellular carcinoma.

Hepatitis B virus infection is the most common cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma worldwide. In areas hyperendemic for HBV infection, the related complications occur mostly during adulthood. However, nearly half of all primary infection in chronic carriers occurs in the perinatal period through maternal transmission, the other half arising from horizontal transmission mainly through intrafamilial spread or injection using unsterilized needles. A universal vaccination programme is better than immunization for at-risk groups. Hepatitis B vaccination should be integrated into the Expanded Programme on Immunization in children. Universal immunization against hepatitis B virus has proved to be effective in reducing the hepatitis B carrier rate to one-tenth of the prevalence before the vaccination programme in highly endemic areas, and the incidence of hepatocellular carcinoma in children has also been shown to be significantly reduced. Continued efforts to implement universal vaccination programmes worldwide will very likely reduce the incidence of hepatitis B virus-related diseases, particularly liver cirrhosis and hepatocellular carcinoma.

Carcinoma, Hepatocellular↗
PubMed1999

Long-term follow-up of duodenal ulcer in children before and after eradication of Helicobacter pylori.

BACKGROUND: Helicobacter pylori is a well-known cause of chronic antral gastritis and plays an important role in the pathogenesis of peptic ulcer disease in adults. However, because of the relatively low incidence of duodenal ulcer in childhood, few studies have been directed specifically at the relation between the treatment of H. pylori infection and duodenal ulcer in children. An evaluation in a larger patient population is necessary to draw a conclusion. METHODS: Twenty-six children with duodenal ulcer and H. pylori antral gastritis received triple therapy (amoxicillin, bismuth, and metronidazole) to investigate whether eradication of the organisms can promote healing and prevent relapse of the ulcers in children. Endoscopic examinations were performed before, 2 months, and 12 months after the beginning of treatment. RESULTS: H. pylori infection was eradicated in 25 (96%) of the 26 patients who underwent upper endoscopic follow-up. Clinical improvement and ulcer healing were achieved in 24 (92%) of 26 children. During a mean follow-up of nearly 2 years, the annual ulcer relapse rate was estimated to be 9%. CONCLUSIONS: Triple therapy is the treatment of choice for endoscopically proven duodenal ulcer and histologically proven H. pylori antral gastritis in children. It strongly supports a causal relation between H. pylori and duodenal ulcer disease in children.

Adolescent↗
PubMed1999

Cytokine release of peripheral blood mononuclear cells in children with chronic hepatitis B virus infection.

BACKGROUND: Immune response to hepatitis B virus (HBV) antigens or mitogens in Asian children with chronic HBV infection who are mainly perinatally infected has not been studied in connection with the production of various cytokines, although these patients are considered to be less responsive to antiviral therapy. METHODS: The production of the cytokines interferon (IFN)-gamma, lymphotoxin, interleukin (IL)-4, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-1beta by peripheral blood mononuclear cells (PBMCs) was studied in 17 hepatitis B surface antigen (HBsAg) carrier children with raised alanine transferase levels (group 1), 17 HBsAg carrier children with normal alanine transferase levels (group 2), and 20 healthy noncarrier control subjects (group 3). RESULTS: Hepatitis B core antigen (HBcAg)-stimulated IFN-gamma production was significantly higher in group 1 than in groups 2 and 3, serum HBeAg cleared within 1 year in five of eight children in group 1 with stimulation indexes higher than 3, and HBcAg-induced IL-4 secretion was minimal in all groups. Interferon-gamma produced by PBMCs stimulated by purified HBsAg did not differ among the three groups. Higher lymphotoxin production by PBMCs stimulated by HBcAg was also noted in groups 1 and 2 than in group 3. Lipopolysaccharide (LPS)-stimulated TNF-alpha production by PBMCs was significantly higher in group 1 than in group 2. There was no association between HBeAg-anti-HBe status and production of various cytokines. No differences were seen in the profile of cytokines induced by HBV antigens or LPS in children of carrier mothers compared with children of HBsAg-negative mothers. CONCLUSION: Increased IFN-gamma production resulting from HBcAg-specific T-helper lymphocyte type 1 response, and increased TNF-alpha production may contribute to cell-mediated antiviral immune response in children with chronic hepatitis B. In HBV carrier children, the ability to produce the studied cytokines is related to whether an endogenous immune attempt to eliminate HBV infection emerges in the patients but is not related to the different modes of acquisition of HBV infection.

Adolescent↗
PubMed1999

Long term immune response of universal hepatitis B vaccination in infancy: a community-based study in Taiwan.

OBJECTIVES: To evaluate the long term immunity provided by a universal hepatitis B vaccination program in infancy and the booster effect on school age children who had no protective antibody titers to hepatitis B surface antigen. METHODS: We conducted a community-based seroepidemiologic study of 1337 healthy 7-year-old children in Taiwan one decade after the implementation of a mass hepatitis B vaccination program. A booster vaccination was suggested for noncarrier children who did not have protective titers of surface antibody. Serologic responses and infection rates were compared with those of the nonboostered children. In a nonselected group of 39 volunteer noncarrier vaccinees, quantitative serologic response was determined before, 1 month after a booster vaccination and 1 year later. RESULTS: A total of 572 children (42.8%) had low concentrations of surface antibody, and 9 were hepatitis B surface antigen carriers (0.7%). Eighty-two percent of "nonprotected" vaccinees showed immunologic memory to a booster dose and developed protective antibody titers 1 month later; 60.6% maintained protective titers 1 year later. The frequency of new hepatitis B virus infection was similar for those who received a booster and those who did not as investigated by the core antibody seroconversion during 1-year follow-up. However, the risk was low, with annual incidences of <1% in both groups, and none became chronic carriers. CONCLUSION: According to these data a universal vaccination program in infancy provides adequate protection against hepatitis B virus infection for school age children and a booster vaccination is not recommended.

Child↗
PubMed1999

Primary sclerosing cholangitis in a child.

Primary sclerosing cholangitis (PSC) is a rare disease in Taiwan and has not been described in Taiwanese children previously. We report a 4-year-old girl who presented with prolonged fever, eosinophilia (11%), hepatomegaly, and markedly elevated serum levels of alkaline phosphatase (3,318 IU/L) and gamma-glutamyl transpeptidase (475 IU/L). Subsequent investigations including endoscopic retrograde cholangiopancreatography and liver histology confirmed the diagnosis fo PSC. Treatment with a low dose of prednisolone for 2 months and ursodeoxycholic acid during 32 months of follow-up resulted in clinical remission and halted disease progression. A high index of suspicion is necessary for physicians to diagnose this disorder in children with chronic liver disease. Our experience in this case indicates that therapy with prednisolone and ursodeoxycholic acid may be helpful for the treatment of PSC in children, and suggests the need for more trials of combined therapy.

Age of Onset↗
PubMed1999

Protamine enhances the efficiency of liposome-mediated gene transfer in a cultured human hepatoma cell line.

Protamine, used clinically as an antidote for heparin, is a small protein with high arginine content and is potent in folding DNA. Protamine and DNA can form a compact structure, protecting DNA from digestion by intracellular enzymes. Protamine may, therefore, enhance the efficiency of gene transfer. In this study, we tested the ability of protamine to improve liposome-mediated gene transfer efficiency in a human hepatoma cell line. The results of a preliminary gel retardation assay indicated that 10 micrograms was the minimal amount of protamine sulfate needed to completely bind 5 micrograms of a plasmid containing a reporter gene, green fluorescent protein (GFP). For transfection assays, protamine (0, 10, 50, 100, and 500 micrograms) was added to a DNA-liposome mixture (5 micrograms DNA and 20 micrograms of a mixed formulation of 2,3-dioleyloxy-N-[2(sperminecarboxamido)ethyl]-N, N-dimethyl-1-propanaminium trifluoroacetate and dioleoylphosphatidylethanolamine) to transfect cultured Huh7 cells. Transfected cells (those expressing GFP) were counted by using flow cytometry. The expression index (EI) was calculated as the transfection efficiency (% of transfected cells) with protamine divided by the transfection efficiency with DNA and liposome only. Our results show that protamine sulfate (in a range of 10-100, 10 micrograms being most efficient) addition to the liposome-DNA mixture significantly increases the EI, and transfection efficiency of GFP in Huh7 cells.

Animals↗
PubMed1998

Cardiovascular disease risk factors and preventive practices among adults--United States, 1994: a behavioral risk factor atlas. Behavioral Risk Factor Surveillance System State Coordinators.

UNLABELLED: PROBLEM/CONDITIONS: Cardiovascular disease (CVD), including coronary heart disease (CHD) and stroke, is the leading cause of death in the United States, and state rates of CVD vary by state and by region of the country. Several behavioral risk factors (i.e., overweight, physical inactivity, smoking, hypertension, and diabetes mellitus) and preventive practices (i.e., weight loss and smoking cessation) are associated with the development of CVD and also vary geographically. This summary displays and analyzes geographic variation in the prevalences of selected CVD risk factors. REPORTING PERIOD: 1994 (1992 for prevalence of hypertension). DESCRIPTION OF SYSTEM: The Behavioral Risk Factor Surveillance System (BRFSS) is a state-based random-digit-dialing telephone survey of noninstitutionalized adults aged > or =18 years; 50 states and the District of Columbia participated in BRFSS in 1994, and 48 states and the District of Columbia participated in 1992. METHODS: Several different analyses were conducted: a) analysis of state risk factor and preventive practice prevalences by sex and race (i.e., black and white); b) mapping; c) cluster analysis; d) correlations of state prevalence rates by sex and race; and e) regression of state risk factor prevalences on state CHD and stroke mortality rates. RESULTS: Mapping the prevalence of selected CVD risk factors and preventive health practices indicates substantial geographic variation for black and white men and women, as confirmed by cluster analysis. Data for blacks are limited by small sample size, especially in western states. Geographic clustering is found for physical inactivity, smoking, and risk factor combinations. Risk factor prevalences are generally lower in the West and higher in the East. White men and white women are more similar in state risk factor rates than other race-sex pairs; white women and black women ranked second in similarity. State prevalences of physical inactivity and hypertension are strongly associated with state mortality rates of CVD. INTERPRETATION: Geographic patterns of risk factor prevalence suggest the presence (or absence) of sociocultural environments that promote (or inhibit) the given risk factor or preventive behavior. Because the risk factors examined in this summary are associated with CVD, further exploration of the reasons underlying observed geographic patterns might be useful. The BRFSS will continue to provide geographic data about cardiovascular health behaviors with a possible emphasis on more data-based small- area analyses and mapping. This will permit states to more adequately monitor trends that affect the burden of CVD in their regions and the United States. Mapping also facilitates the exploration of patterns of morbidity, health-care use, and mortality, as well as the epidemiology of risk factors. Finally, by identifying those segments of the population with high levels of these risk factors and lower levels of the preventive health practices, public health personnel can better allocate resources and target intervention efforts for the prevention of CVD.

Adult↗
PubMed1998

Successful arterial switch operation in a low-birth-weight neonate who had transposition of the great arteries and advanced necrotizing enterocolitis.

A low-birth-weight (LBW; 1,940 g) girl was born at the gestational age of 36 weeks without any perinatal insult. Transposition of the great arteries (TGA) with a large patent ductus arteriosus (PDA) and interatrial shunt was detected. Stage IIIB necrotizing enterocolitis (NEC) developed 46 hours after birth. She received ileostomy and drainage. Arterial switch operation was successfully performed at 23 days of age when her weight was 1,900 g. The enterostomy was successfully repaired at 104 days of age.

Ductus Arteriosus, Patent↗
PubMed1998

Hepatitis B surface antigenemia at birth: a long-term follow-up study.

OBJECTIVE: To investigate the prevalence and outcome of hepatitis B surface antigenemia in newborns of hepatitis B e antigen (HBeAg)-positive hepatitis B surface antigen (HBsAg) carrier mothers under the current immunoprophylaxis program. STUDY DESIGN: From 1984 to 1993, 665 high-risk newborns born to HBeAg-positive HBsAg carrier mothers were prospectively recruited. The newborns were tested for HBsAg soon after birth, before hepatitis B immune globulin administration. All newborns received hepatitis B immune globulin within 24 hours after birth plus subsequent hepatitis B vaccination. Those who were seropositive for HBsAg at birth were regularly followed up for their hepatitis B virus (HBV) markers, liver function profiles, and alpha-fetoprotein levels from 1984 to 1996. RESULTS: Sixteen (2.4%) of the 665 subjects were found to be seropositive for HBsAg at birth, and all remained HBsAg-positive at 6 months of age. Twelve of the 16 received long-term follow-up care, and all were confirmed to have chronic HBV infection. Of the 12, 2 had HBeAg seroconversion, and 1 had alanine aminotransferase flares without HBeAg seroconversion. Delayed appearance of hepatitis B core antibody (anti-HBc) occurred in 2 without alanine aminotransferase elevation. CONCLUSIONS: Current immunoprophylaxis strategy does not protect newborns with surface antigenemia, apparently acquired in utero, from becoming HBV carriers. Immunologic attempts to eliminate HBV may occur in carrier children infected in utero, despite their profound immune tolerance to HBV.

Alanine Transaminase↗
PubMed1998

Antibodies to E2 protein of hepatitis G virus in children: different responses according to age at infection.

OBJECTIVES: To study viral persistence and antibody responses after hepatitis G virus (HGV) infection in children of various ages. STUDY DESIGN: We performed an enzyme immunoassay for antibodies to E2 protein (anti-E2) of HGV and reverse-transcription polymerase chain reaction assay for HGV RNA on serum samples. RESULTS: Of 28 infants born to HGV RNA-positive mothers, 17 were found to be positive for HGV RNA. None were positive for anti-E2. All 17 infected infants continued to have viremia except 1 who converted to HGV RNA-negative status at 24 months. Six infants had mild elevations of alanine aminotransferase levels (5 HGV-positive and 1 HGV-negative). An additional 14 HGV-infected children (aged 6 months to 14 years) with posttransfusion HGV infection were tested for anti-E2 3 months and 12 months after blood transfusion. None of the HGV RNA-positive serum samples were positive for anti-E2; however, 4 of the 8 children with resolving HGV infection were positive for anti-E2 1 year later. CONCLUSIONS: Mother-to-infant transmission of HGV resulted in a high viral persistence rate and lack of immune responses to HGV. In contrast, anti-E2 appeared in children who recovered from posttransfusion HGV infection. Mode of transmission and age at infection may be important factors in determining persistent HGV infection and defective immune response to HGV.

Adenovirus E2 Proteins↗
PubMed1998

Precore stop codon mutant in chronic hepatitis B virus infection in children: its relation to hepatitis B e seroconversion and maternal hepatitis B surface antigen.

BACKGROUND/AIMS: The aims of this study were to investigate the significance of the precore stop codon mutant in the natural course of hepatitis B virus infection in children, and the influence of maternal transmission. METHODS: Sequential sera from 80 hepatitis B virus carrier children both before and after e seroconversion during long-term follow-up were studied using the polymerase chain reaction-amplification created restriction site method. Direct sequencing of the precore region was performed in 89 sera from 32 of the 80 children. RESULTS: The precore stop codon mutant coexisting with wild strain was found in 10% of children initially, and later in 25% of children before e seroconversion. After e seroconversion, wild type was still present in 75% and mutant in 39% of children at the end of follow-up. The mutant alone was present in 15% of anti-HBe positive children without concomitant aminotransferase elevation. Children with earlier emergence of this mutant tended to have higher peak aminotransferase levels. This mutant emerged less frequently in children of hepatitis B virus carrier mothers (37.5%) than in those of non-carrier mothers (65%) (p<0.05). CONCLUSIONS: These observations suggest that this mutant is selected by host immune pressure, but is not an initiator in the loss of immune tolerance during childhood chronic hepatitis B virus infection.

Adolescent↗
PubMed1998

Purification and properties of beta-N-Acetylhexosaminidase from cabbage.

beta-N-Acetylhexosaminidase was purified from the extract of cabbage by sequential steps of ammonium sulfate fractionation, chromatofocusing, DEAE-Sepharose CL-6B ion exchange chromatography and Sephacryl S-200 HR gel filtration. By these steps, the purity of the enzyme increased by 256 fold with a recovery of 8%. The purified enzyme was homogeneous as examined by native PAGE. It showed an optimal pH of 4, an optimal temperature of 60 degrees C and a Km of 0.94 mM for hydrolysis of pNp-beta-GlcNAc. The molecular mass of the enzyme determined from filtration through Sephacryl S-200 was 150 kDa. Three subunits with molecular mass of 64, 57 and 51 kDa were observed as determined by SDS-PAGE. NBS (0.025 mM), DEPC (3 mM) and WRK (30 mM) significantly inhibited the activity of the enzyme. The enzyme also showed activity toward pNp-beta-GalNAc, N,N'-diacetylchitobiose, N,N',N"-triacetylchitotriose and N,N',N",N"'-tetraacetyl chitotetraose but showed no activity toward pNp-alpha-GlcNAc, chitin and ethylene glycol chitin.

Brassica↗
PubMed1998

Mother-to-infant transmission of GB virus C/hepatitis G virus: the role of high-titered maternal viremia and mode of delivery.

To study mother-to-infant transmission of GB virus C/hepatitis G virus (GBV-C/HGV), blood samples of infants born to carrier mothers were collected beginning 3 months after birth and were tested for GBV-C/HGV RNA until 1 year of age. Of 2046 mothers, 2.1% were positive for GBV-C/HGV RNA, and 25 of their infants were followed for a median of 12 months. Thirteen infants (52%) were viremic, and infection became persistent in all. Maternal GBV-C/HGV RNA levels of this group were >10(7) copies/mL. Nucleotide sequence comparison in 5 viremic mother-infant pairs revealed a homology of 93%-98.2%, and none delivered by elective cesarean section. In comparison, of the 12 uninfected infants' mothers, 10 had lower GBV-C/HGV RNA levels (mean, 5 x 10(4) copies/mL), and the remaining 2 high-titered mothers had elective cesarean section. Thus, high-titered maternal viremia and mode of delivery are closely associated with the mother-to-infant transmission of GBV-C/HGV to infants, and the infection usually becomes persistent.

Carrier State↗
PubMed1998

"Hotness" stability of chicken hot-wing products as affected by preparation methods and storage.

Chicken hot-drumettes containing 2% cayenne pepper were prepared using three different cooking methods and stored under two different temperatures for "hotness" evaluation. Results demonstrated that the hotness of the samples were highest when products were cooked in a microwave oven, followed by convection oven, and least hot by deep-fat frying. Regardless of the cooking method, the degree of hotness of the hot-drumette decreased drastically during refrigerated storage. Results also indicated that the loss of hotness was associated with the increase of 2-thiobarbituric acid (TBA) values in the product. The addition of antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), rosemary, and sodium nitrate during preparation or vacuum packaging retarded lipid oxidation of chicken hot-drumettes and retarded the loss of hotness of the products during refrigerated storage.

Animals↗