PubMed Health⌕ Search

Biomedical subjects

M H Chang

Publications and source records attributed to M H Chang.

At least 37 records · Page 2Linked to original sources
PubMed2000

Immunogenicity and reactogenicity of the combined hepatitis A and B vaccine in young adults.

The combination of hepatitis A virus (HAV) and hepatitis B virus (HBV) vaccinations can offer convenience, increased compliance and cost saving. We have studied the immunogenicity, reactogenicity and safety of combined hepatitis A and B vaccination in young adults (16-35 years old). Eighty healthy young adults were divided into two random groups. One group received the combined hepatitis A and B vaccine (HAB) in one arm while the other group was administered concomitant hepatitis A and B vaccines (HAV + HBV) in the right and left arms, respectively. The immunogenicity, reactogenicity and safety were assessed after each dose in both the groups. In local symptoms, the percentage of the combined HAB group was lower than the HAV + HBV group, and the general symptoms were noted in approximately 30% of each group without any significant difference. No serious adverse effects were noted. All the subjects were seropositive for antibody to hepatitis A virus (anti-HAV) after one dose of vaccine, and remained seropositive after three doses in both groups. The seropositive rate for antibody to hepatitis B surface antigen (anti-HBs) was significantly higher (84%) in the combined HAB group than the concomitant HAV + HBV group (62%), (p<0.05) after dose two, and all the subjects were seropositive (100%) after the third dose. The GMTs of anti-HAV and anti-HBs were not significantly different between groups 1 and 2 (p>0.1) except in month 6 when the GMT of anti-HBs was higher in HAB group (p=0.0039). The combined HAB vaccine was found to be safe, well tolerated and had less local symptoms in young adults. The immunogenicity and reactogenicity were similar to the concomitant HAV + HBV vaccines.

Adult↗
PubMed2000

Somatic mutations of beta-catenin play a crucial role in the tumorigenesis of sporadic hepatoblastoma.

Hepatoblastoma (HB) is the most common malignant hepatic tumor during early childhood. Its molecular pathogenesis is still poorly understood. Mutations of adenomatous polyposis coli (APC) gene have been identified in sporadic cases and in individuals associated with familial adenomatous polyposis syndrome. beta-catenin is a key element in the cadherin-mediated cell adhesion system and Wnt/wingless pathway, and is controlled by APC. APC affects the degradation of beta-catenin by its NH(2)-terminal phosphorylation on the serine/threonine residues of exon 3. Mutations of these phosphorylation sites are primary targets for activating mutations in several types of human cancer and lead to nuclear accumulation of beta-catenin protein. In this study, we examined nine patients with HB using immunohistochemistry and direct DNA sequencing. All nine cases showed predominant nuclear expression of beta-catenin. Eight cases (89%) showed mutations involving exon 3 of the beta-catenin gene, including five with deletions and three with missense mutations. All five deletions were in-frame deletions without frameshift. The very high frequency of mutations in the beta-catenin gene suggests that beta-catenin mutations are crucial in the tumorigenesis of HB.

Amino Acid Sequence↗
PubMed2000

Glucose-6-phosphatase gene mutations in Taiwan Chinese patients with glycogen storage disease type Ia.

Glycogen storage disease type Ia (GSD Ia) is caused by a deficiency of glucose-6-phosphatase (G6Pase) activity. Eighteen GSD Ia families were studied for G6Pase gene mutations. Thirty-two mutations were found in 36 GSD Ia chromosomes: 16 were 727 G-->T (44.44%); 13 were R83H (327 G-->T; 36.11%); 1 was 341delG; 1 was 933insAA; and 1 was 793 G-->T. The 727 G-->T and R83H mutations together accounted for 80.56% (29/36) of the GSD Ia chromosomes. These two mutations were easily examined by polymerase chain reaction-based methods, and the prenatal diagnosis of a non-affected fetus was successfully made. The 727 G-->T mutation is the predominant mutation in Japanese GSD Ia patients, but is rarely seen in Western counties. The 727 G-->T mutation is also the most prevalent mutation in Taiwan Chinese, although the incidence is not as high as in Japan.

Asian People↗
PubMed2000

The cause of slowed forearm median conduction velocity in carpal tunnel syndrome.

OBJECTIVES: Attempting to answer a debate concerning the etiopathogenesis of the decreased forearm median motor conduction velocity (FMMCV), we tried to use proximal stimulation at the wrist, elbow, mid-arm and axillary regions to determine segmental median motor conduction velocity (MMCV). We also correlated the FMMCV with median motor distal latency (MMDL) and compound muscle action potential (CMAP) amplitudes of the abductor pollicis brevis (APB) muscle in order to assess whether the conduction block of large myelinating fibers or retrograde axonal atrophy was the major cause of the decreased FMMCV. BACKGROUND: The cause of the decreased FMMCV resulting from either the conduction block of the large myelinating fibers at the wrist or distal compression with retrograde axonal atrophy remains an unresolved issue at the moment. Animal models have supported the hypothesis that the retrograde axonal atrophy might also occur in humans. Other authors believe the standard FMMCV is calculated by subtracting the distal latency which may not represent an exact assessment of FMMCV but rather the velocity of small fibers that persist through the carpal tunnel. SUBJECTS AND METHODS: Patients with the clinical symptoms and signs of carpal tunnel syndrome (CTS) confirmed using standard electrodiagnosis were included. The patients were arbitrarily divided into two groups based on the FMMCV, one with reduced FMMCV (n = 20, FMMCV < 50 m/s) and the other with normal FMMCV (n = 35, FMMCV> or =50 m/s). Age-matched volunteers served as controls. We explored motor conduction proximally at wrist, elbow, mid-arm and axillary stimulation, and recorded at the APB muscles. Based on the latency differences, we calculated the FMMCV, distal arm MMCV (DAMMCV) and proximal arm MMCV (PAMMCV), and compared the conduction velocity (CV) differences of DAMMCV-FMMCV, PAMMCV-FMMCV and PAMMCV-DAMMCV in the two patient groups and the control. Furthermore, we correlated FMMCV with MMDL and CMAP amplitudes of APB muscle because MMDL and CMAP amplitudes might reflect the integrity of the large myelinating fibers. RESULTS: CMAP amplitudes of APB muscle at wrist stimulation and MMDL were not correlated with FMMCV in either of the two patient groups; however, the CMAP amplitude was markedly decreased and MMDL was significantly prolonged when compared with normal controls. The significant increase of CV gradient of DAMMCV-FMMCV and PAMMCV-FMMCV without an equal increase of CV gradient of PAMMCV-DAMMCV only occurred in the reduced FMMCV patient group, suggesting that the conduction block is not the primary cause. The CV gradient of DAMMCV-FMMCV and PAMMCV-DAMMCV did not show any significant difference between patients with the normal FMMCV and the control group. CONCLUSION: The retrograde axonal atrophy, not selective damage of the large fibers at the wrist, was the direct cause of the decreased FMMCV.

Action Potentials↗
PubMed2000

Natural history of hepatitis B virus infection in children.

Hepatitis B virus (HBV) infection during childhood can cause acute, fulminant or chronic hepatitis, liver cirrhosis, and liver cancer. Approximately 90% of the infants of hepatitis B e antigen (HBeAg) seropositive mothers become hepatitis B surface antigen (HBsAg) carriers. Children chronically infected are mostly asymptomatic. Although liver damage is usually mild during childhood, severe liver disease, including cirrhosis and hepatocellular carcinoma, may develop insidiously for 2-7 years. Spontaneous HBeAg seroconversion occurs gradually as the age of the child increases. Viral replication is reduced during this process, which is usually preceded by an elevation of aminotransferases. In a long-term follow-up study, the annual HBeAg seroconversion rate was 4-5% in children older than 3 years of age and less than 2% in children under 3 years. The annual seroconversion rate of HBsAg was very low (0.56%). Age at infection, maternal HBsAg and HBeAg status, host immune status, and possibly the HBV strain are the main factors determining the course of HBV infection in children.

Asia↗
PubMed2000

Treatment of chronic hepatitis C virus infection in children.

Hepatitis C virus (HCV) infection may occur in infants and children, although it is much less common than it is in adults. The main transmission routes include mother-to-infant transmission, use of HCV infected blood products, unsterile needles or syringes and other invasive procedures. The natural course of HCV infection in children is variable: some (20-40%) develop an acute resolving infection and spontaneous regression occurs in approximately one-third of infants of HCV infected mothers before 2 years of age. Approximately 60-80% of HCV infected children develop a chronic infection with varying degrees of activity and fibrosis, mostly mild during childhood. However, the potential risks of liver cirrhosis and hepatoma during later life are obvious. Interferon is the main agent used to treat HCV infection in children. The response to interferon at the end of 4-12 months of therapy ranges from 25-90%. A sustained response was found in 36-56% of children 6-36 months after the end of therapy. The duration of therapy is recommended to be 12 months. At the end of 3 months, an evaluation of the response is indicated in the majority of children, except those with thalassemia, in whom evaluation of response should be conducted at the end of 6 months of therapy. The benefit of other therapies, such as combination therapy with interferon and ribavirin in children with hepatitis C is currently under investigation.

Antiviral Agents↗
PubMed2000

Long-term follow-up study of core gene deletion mutants in children with chronic hepatitis B virus infection.

Core gene deletion mutants of hepatitis B virus (HBV) have been identified in adults. Because the acquisition of HBV occurs mainly in infancy and childhood in hyperendemic areas, this study aimed to learn the temporal profile of such mutants in children with chronic HBV infection. We have followed up 365 HBV-infected children for more than 10 years and screened out HBV core gene deletion from their sera. Serial serum samples of positive cases were subjected to HBV-DNA nucleotide sequence analyses and quantification. Deletion mutants were found in 18 of the 365 patients (4.9%). Most cases (15 of 18) with deletion mutants heralded hepatitis B e antigen (HBeAg) seroconversion phase, while the other cases (3 of 18) remained in HBeAg-seropositive phase. Deletion mutants disappeared after HBeAg seroconversion except in 1 child. Decreased HBV-DNA levels accompanied deletion mutants for those who finally underwent HBeAg seroconversion, but the HBV-DNA level did not decline if there was no seroconversion. Deletion mutants were not associated with a particularly high peak liver enzyme. Core gene deletion mutants could appear as early as the age of 5. The duration of their appearance was 0.5 to 5 years. Horizontal rather than perinatal transmission of HBV was a favorable factor for these mutants to develop. Deletion fragments were located in the middle part of core gene. The emergence of the mutants was likely the result of host-viral interaction and mostly signified HBeAg seroconversion within 1 year. Core gene deletion mutants appeared preferably in children acquiring HBV by horizontal transmission.

Adolescent↗
PubMed2000

Reduction of Campylobacter jejuni in a simulated chicken digestive tract by Lactobacilli cultures.

Studies were conducted to investigate the impact of a selected lactobacilli mixed culture on Campylobacter jejuni in simulated chicken digestive tract models. Veronal buffer solutions corresponding to the pH of successive segments of the chicken digestive tract were prepared. The lactobacilli mixtures were prepared by mixing four fresh lactobacilli cultures, including Lactobacillus acidophilus, Lactobacillus fermenentum, Lactobacillus crispatus, and Lactobacillus brevis. The C. jejuni and lactobacilli mixture were mixed with sterile poultry feed, and the previously prepared veronal buffer solutions were then added separately. The mixture was incubated at 41.1 degrees C for various lengths of time with periodic agitation. The feed passage time for five segments of the digestive tract were adopted: crop (pH 4.5), 30 min; proventriculus (pH 4.4), 15 min; gizzard (pH 2.6), 90 min; small intestine (pH 6.2), 90 min; and large intestine (pH 6.3), 15 min. The Campylobacter and lactobacilli were enumerated. An antagonistic effect on C. jejuni by the tested lactobacilli spp. was found in individual sections and the complete simulated digestive tract models. In the simulated complete chicken digestion system, no C. jejuni were found during the final incubation period when a lactobacilli mixture was present. The results of this in vitro study indicate the potential value of future in vivo studies.

Animals↗
PubMed2000

Saposins A, B, C, and D in plasma of patients with lysosomal storage disorders.

BACKGROUND: Early diagnosis of lysosomal storage disorders (LSDs), before the onset of irreversible pathology, will be critical for maximum efficacy of many current and proposed therapies. To search for potential markers of LSDs, we measured saposins A, B, C, and D in patients with these disorders. METHODS: Four time-delayed fluorescence immunoquantification assays were used to measure each of the saposins in plasma from 111 unaffected individuals and 334 LSD-affected individuals, representing 28 different disorders. RESULTS: Saposin A was increased above the 95th centile of the control population in 59% of LSD patients; saposins B, C, and D were increased in 25%, 61%, and 57%, respectively. Saposins were increased in patients from several LSD groups that in previous studies did not show an increase of lysosome-associated membrane protein-1 (LAMP-1). CONCLUSION: Saposins may be useful markers for LSDs when used in conjunction with LAMP-1.

Adolescent↗
PubMed2000

Unusual signs for dural arteriovenous fistulas with diffuse basal ganglia and cerebral calcification.

We present a case of multiple dural arteriovenous fistulas (AVFs) in a 60-year-old man with the chief complaint of worsening headache, altered mental status and progressively unsteady gait over the course of one year. Computerized tomography revealed diffuse, symmetric calcification in the bilateral basal ganglia and bilateral periventricular and subcortical white matter. Magnetic resonance imaging revealed multiple, enhanced, punctate and linear vessels. These images were due to reflux into the parenchymal veins in the dural AVF of the superior sagittal sinus within the basal ganglia and deep white matter of both cerebral hemispheres. Cerebral angiography disclosed multiple dural AVFs. The exact mechanism of basal ganglia and subcortical calcification is proposed to be an arterial steal phenomenon or persistent venous congestion, with calcification occurring in a chronic hypoperfused state or with dystrophic changes in the walls of congested veins.

Arteriovenous Fistula↗
PubMed2000

Accurate diagnosis of Helicobacter pylori infection by stool antigen test and 6 other currently available tests in children.

Invasive and noninvasive tests have been developed for the diagnosis of Helicobacter pylori infection. Because H pylori infection is acquired in childhood and adolescence, accurate diagnosis of the infection in the pediatric population is important. We conducted a study to compare invasive tests: culture, biopsy urease test, histology, and polymerase chain reaction on gastric biopsy specimens, with noninvasive tests: serology, (13)C-urea breath test, and a new diagnostic modality, stool antigen test to diagnose H pylori infection. A total of 53 children with symptoms were enrolled in this study, and all had completed the 7 diagnostic tests for H pylori. All the diagnostic tests except serology were excellent methods of diagnosing H pylori infection in children; the diagnostic accuracy was as follows: stool antigen test 96.2%, biopsy urease test 96.2%, histology 98.1%, polymerase chain reaction 94.3%, culture 98.1%, (13)C-urea breath test 100%, and serology 84.9%. The stool antigen test, being highly sensitive and specific, will be potentially very helpful in diagnosing H pylori infection in children.

Adolescent↗
PubMed2000

Metabolic disorders mimicking Reye's syndrome.

BACKGROUND: Several metabolic disorders such as encephalopathy and hepatic dysfunction have been described as Reye's-like syndrome because they present with similar clinical manifestations that mimic Reye's syndrome. We performed a retrospective study to explore the underlying metabolic etiologies of Reye's-like syndrome in patients treated at National Taiwan University Hospital. METHODS: From January 1991 to June 1998, 19 children with a syndrome fitting the Reye's-like syndrome description were identified for study. Urine organic acid analysis, plasma amino acid analysis, liver pathology, and skin fibroblast enzyme assays were studied during the acute stage of illness. RESULTS: The etiologies of patients' syndromes included urea cycle disorders (n = 7), glycogen storage disease type Ia (4), primary carnitine deficiency (2), hereditary fructose intolerance (1), methylmalonic acidemia (2), and 3-hydroxy-3-methylglutaric acidemia (1). Fatty acid oxidation defects were suspected in the remaining two cases. CONCLUSIONS: A significant number of patients who present with Reye's-like syndrome have an underlying inherited metabolic disorder. In patients with Reye's-like syndrome, an accurate diagnosis is essential to ensure normal growth and development and to prevent recurrence of the condition.

Child, Preschool↗
PubMed1999

Decreased diversity of hepatitis C virus quasispecies during bone marrow transplantation.

To elucidate the role of host immune status in the evolution and complexity of hepatitis C virus (HCV) quasispecies, three chronic HCV-infected patients who underwent bone marrow transplantation (BMT) were studied. The three transplanted patients' sera were sampled at pre-BMT, 3 months after BMT, and 12 months after BMT and the nucleotide diversity and substitution of the hypervariable region (HVR) of HCV quasispecies were analyzed. The nucleotide diversity was high at the pre-BMT period (28.2-43.4 x 10(-2) nucleotide difference/site). HVR of HCV quasispecies then became homogeneous in the first 3 months after BMT (0.11-6.40 x 10(-2) nucleotide difference/site). The nucleotide diversity of HVR at 12 months after BMT of all three patients was higher than that of 3 months after BMT but still lower than that of pre-BMT (2.09-6.40 x 10(-2) nucleotide difference/site). The analysis on nucleotide substitution rate showed a higher value between pre-BMT and 3 months after BMT (0.624-0.708 nucleotide difference/site per year) than that between 3 months and 12 months after BMT (0.072-0.127 nucleotide difference/site per year). HCV RNA titer decreased when the host had a low white cell count and increased accordingly. It was concluded that the evolution of HVR of HCV quasispecies related to the immune status of the host during BMT: after immunosuppression, an initial increase of viral populations was followed by the emergence of a dominant strain while the quasispecies gradually recovered as the immunity of the host gained its competence.

Adolescent↗
PubMed1999

Synthesis and evaluation of 2 beta-oxyimino and alkenylpenicillanic acid sulfone derivatives as beta-lactamase inhibitors.

The synthesis and in vitro synergies of 2 beta-alkenyl and oxyiminopenam sulfone derivatives are described. Most of the compounds synthesized exhibited good inhibitory activities and synergistic antibacterial activities with piperacillin and ceftriaxone, respectively, against several beta-lactamase producing strains. Particularly the 2 beta-alkenylpenam sulfone derivatives. 1e and 1g, showed good synergistic activity with ceftriaxone against Citrobacter freundi NIH 10018-68 and Proteus vulgaris 20. Also the compounds 2a, 2c, and 2f, 2 beta-oxyiminopenam sulfone derivatives, exhibited improved synergistic activity with piperacillin against Citrobacter freundi NIH 10018-68.

Ceftriaxone↗
PubMed1999

Long-term response to hepatitis B vaccination and response to booster in children born to mothers with hepatitis B e antigen.

Hepatitis B (HB) vaccine provides an uncertain duration of protection and the optimal timing of booster vaccine remains unclear. This study examined the immune response at 10 years of 118 children who had developed protective anti-HB surface (anti-HBs) levels after a primary series of HB immunizations in infancy. All of the children were born to hepatitis B e Antigen (HBeAg)-positive hepatitis B surface antigen (HBsAg) carrier mothers. HB markers in all subjects and cellular immune response in some were determined. A booster was given to all subjects after the collection of samples and another blood sample was collected 4 weeks later. The results showed that a total of 39 (33%) of the children were seronegative for anti-HBs. T-cell proliferative response to HBsAg was noted in 47% of children. On HBsAg stimulation, leukocyte samples from a significantly higher proportion of subjects produced cytokines (81% of T cells produced interleukin-2 [IL-2] and 100% produced IL-5). The booster dose of HB vaccine induced the production of a protective level of anti-HBs (>/=10 mIU/mL) in all subjects. Cellular immunity was augmented with a positive rate of 58%, 90%, and 100% for HBsAg-induced T-cell proliferation, IL-2 production, and IL-5 production, respectively. Although 14 (11.9%) of the subjects were HB core antibody positive at 10 years of age, no new HBsAg carrier was detected. The results of this study show that protection afforded by HB vaccination persisted to the age of 10 years in all vaccinees. Immunologic memory was detected in all subjects including those who had lost their anti-HBs seropositivity. These results suggest that no booster vaccination is needed before 10 years of age. The most sensitive marker of immunologic memory is IL-5 production of T cells. (HEPATOLOGY 1999;29:954-959.)

Child↗