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Biomedical subjects

C J Chen

Publications and source records attributed to C J Chen.

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

Immune status in preschool children born after mass hepatitis B vaccination program in Taiwan.

A mass hepatitis B vaccination program began in Taiwan in 1984. In order to determine the immune status of hepatitis B virus (HBV) infection among preschool children, a total of 25 kindergartens in 20 townships and metropolitan precincts in central Taiwan were randomly selected through stratified sampling. Serum specimens of 2130 healthy preschool children aged 2-6 years old were screened for the HBV markers and liver function in 1996. HBV surface antigen (HBsAg), antibody against HBsAg (anti-HBs) and antibody against HBV core antigen (anti-HBc) were tested by reverse passive hemagglutination (RPHA), enzyme immunoassay (EIA) and radioimmunoassay (RIA) using commercial kits. HBV vaccination rate of the preschool children was 98%, and complete vaccination rate (three or four doses of HBV vaccine) was 94%. The HBsAg seropositive rate was 4.5% among incomplete vaccinees and 1.3% among complete vaccinees. The anti-HBs was detectable in 1637 of 2000 complete vaccinees (81.9%) and in 53 of 88 incomplete vaccinees (60.2%). The overall prevalence rate of anti-HBc was 2.4% (52 of 2130). The older the age, the lower the anti-HBs seropositive rate. The anti-HBs seropositive rats for complete vaccinees were 100% at 2 years old and 75% at 6 years old. There were no significant differences in HBsAg-seropositive rates and anti-HBs-seropositive rates among different residential areas or ethnic groups. There were three children who were seropositive on HBsAg, anti-HBs and anti-HBc, whether they were infected by the vaccine-induced escape mutant of HBV deserves scrutiny.

Age Factors↗
PubMed1998

Measurement of equilibrium factor and unattached fraction of radon progeny in Kaohsiung, Taiwan.

To reasonably estimate the population dose from radon, equilibrium factor, Fp, and unattached fraction, fp, of radon progeny are important parameters. A Lucas cell and a working level monitor was used for most Fp measurement. The unattached fraction was measured by SARAD EQF3020. A detached house was chosen to measure the Fp in different rooms. The Fp value depended mainly on the ventilation rate and surface to volume ratio of the rooms. Fp and fp were measured in bedrooms of 14 other dwellings. Two hospitals were also chosen for measurement of Fp in the working place using rooms located in the basement. The average Fp for dwellings was about 0.5 and the average unattached fraction was about 0.055. The radon levels in the hospitals were higher than those in the dwellings but the equilibrium factors in the hospital were very low (about 0.06). The low Fp was attributed to the use of a dehumidifier in the hospitals. Dehumidifiers are popular for reducing fungi problem induced by the high humidity in Taiwan.

Air Pollution, Indoor↗
PubMed1998

Gastric cancer risk in relation to Helicobacter pylori infection and subtypes of intestinal metaplasia.

Helicobacter pylori (H. pylori) infection and intestinal metaplasia (IM) are each associated with an increased risk of gastric cancer (GC). To explore further the influences of H. pylori and IM on GC, H. pylori and subtypes of IM were evaluated in 135 sex and age-matched case and control pairs. Odds ratios (ORs) with 95% confidence intervals of developing GC were calculated for each risk factor using multiple logistic regression analysis. ORs for H. pylori infection and IM were 2.43 (1.29-4.65) and 4.59 (2.58-8.16), respectively, and those for different IM subtypes gave values of 0.82 (0.28-2.36) for type I, 2.03 (0.95-4.34) for type II and 39.75 (14.34-110.2) for type III. Stratification analysis by histological subtype and stage of GC showed a particularly high OR for IM in intestinal type (12.8, 4.73-34.83) and early GC (6.40, 2.25-18.18). Our data indicate that both H. pylori and IM are related to GC risk. Type III IM is a more specific marker of premalignancy, with relevance, in particular, to the early and intestinal type of GC.

Adult↗
PubMed1998

Overexpression of p53 in different subtypes of intestinal metaplasia and gastric cancer.

p53 immunostaining was evaluated in cancerous epithelia and adjacent intestinal metaplasia of 135 gastric cancer specimens. The differential p53 overexpression in different subtypes of intestinal metaplasia and gastric cancer suggests that type III intestinal metaplasia is the commonest lesion in dysplasia-carcinoma transition, particularly in the intestinal type of gastric cancer.

Humans↗
PubMed1998

The cycloplegic effects of cyclopentolate and tropicamide on myopic children.

Thirty-seven myopic children were given either 1-2 drops of 1% cyclopentolate or 1% tropicamide twice with 5 min intervals to evaluate the time course and maximal cycloplegic effect of both agents. The other fifteen subjects were given 1% tropicamide initially, then 1% cyclopentolate given after 30 min of maximal effect of tropicamide appeared to evaluate whether the effect of cyclopentolate was superior to tropicamide. Cycloplegic refraction was measured with an auto-refractometer (Topcon RK-3000) before drug delivery and every 15 min thereafter, for 90 min. The maximal cycloplegic effect of cyclopentolate was around 45 min, then it remained stable until 90 min after the last instillation. The effect of tropicamide was faster than that of cyclopentolate. It was around 30 min, then it stabilized until 75 min. The extra effect of cyclopentolate over tropicamide was minimal (only -0.1D). The power of cornea and astigmatism were not affected by either agent. However, a big variation in astigmatism was noted during the course, especially with cyclopentolate. This study suggests that 1% tropicamide should be a good agent for routine refractive status checking on myopic children.

Accommodation, Ocular↗
PubMed1998

Prevalence and manifestations of hepatitis C seropositivity in children in an endemic area.

BACKGROUND: According to our previous studies, Paisha Township in Penghu Islets is an endemic area for hepatitis B virus and hepatitis C virus (HCV) infection and for hepatocellular carcinoma. We conducted this study to understand the prevalence of anti-HCV seropositivity among children in this area and to observe clinical manifestations of anti-HCV-positive children. METHODS: In March, 1994, 1164 (93.6%) of 1243 students from all 6 kindergartens, 9 primary schools and 3 middle schools in Paisha Township participated in the screening for anti-HCV by enzyme immunoassay with second generation commercial kits (Abbott EIA 2.0). Anti-HCV tests were duplicated for the positive sera in 2 laboratories. All anti-HCV-positive children were followed annually for 2 years. RESULTS: The prevalences of children from kindergartens (ages 3 to 6 years), primary schools (ages 7 to 12 years) and middle schools (ages 13 to 15 years) were 0% (0 of 229), 0.8% (5 of 617) and 1.9% (6 of 318), respectively. Initially the optic density (OD) values of anti-HCV were > 2.0 in 4 cases (36%), between 1.0 and 2.0 in 2 cases, and < 1.0 in the other 5 cases. None had sonographic parenchymal changes in the liver. In the 2-year follow-up of the anti-HCV-positive subjects, type 2a HCV-RNA persisted in 3 of 4 children with an OD of anti-HCV more than 2.0; 2 of them had 2 elevations of alanine transaminase values. Four of 7 children with an OD of 2.0 or less had a decrease in OD values in the follow-up examinations, and 2 of them became anti-HCV-negative. CONCLUSION: Only 36% (4 of 11) of anti-HCV-positive children had an OD of > 2.0. Subjects with sequentially low OD might recover from chronic HCV infection without detectable HCV RNA and with normal alanine aminotransferase values.

Adolescent↗
PubMed1998

Overexpression of mutant p53 and c-erbB-2 proteins and mutations of the p15 and p16 genes in human gastric carcinoma: with respect to histological subtypes and stages.

Although the mechanism remains obscure, two histological subtypes of gastric carcinoma (GC), the diffuse and intestinal types, differ drastically in epidemiological, clinical, pathological and biological characteristics. We investigated whether the genetic alterations of several oncogenes and tumour suppressor genes could be correlated with the two histological subtypes. In 60 patients with GC, the overexpression of mutant p53 and c-erbB-2 oncoproteins was studied using immunohistochemical stains. Mutations of the p15 and p16 tumour suppressor genes were assessed by polymerase chain reaction, Southern blotting, and direct DNA sequencing. Overexpression of c-erbB-2 and p53 was found in 21 (35.0%) and 27 (45.0%) patients, respectively. Overexpression of the c-erbB-2 oncoprotein was more common in the intestinal type (15/32, 46.9%) and the advanced stage (19/45, 42.2%) than in the diffuse type (6/28, 21.4%) and the early stage (2/15, 13.3%) of GC (P<0.05). Similarly, p53 overexpression was more frequently found in the intestinal type (19/32, 59.4%) and the advanced stage (24/45, 53.3%) than in the diffuse type (8/28, 28.6%) and the early stage (3/15, 20.0%) of GC (P<0.05). Homozygous deletions of p16 in exon 1 were found in six (10.0%) patients. Five of them had the intestinal-type advanced GC. Neither point mutations of p16 nor alterations of p15 were detected. The frequency of alterations of p53, c-erbB-2, and p16 was not related to sex and Helicobacter pylori infection. No correlation of genetic changes between any two genes was observed. Our preliminary results indicate alterations in the p15 gene were not important in gastric tumorigenesis, while infrequent homozygous deletions in the p16 gene play a limited role in tumour progression of intestinal-type GC. Moreover, overexpression of c-erbB-2 and p53 is frequently encountered in the intestinal-type advanced GC. Alterations of p53, c-erbB-2 and p16 genes may function independently of each other in gastric carcinogenesis. The association between genetic alterations and histological subtypes supports the notion that a distinct pathogenesis may exist in different histological subtypes.

Aged↗
PubMed1998

Phase variation of hemoglobin utilization in Neisseria gonorrhoeae.

Most Neisseria gonorrhoeae isolates are unable to use human hemoglobin as the sole source of iron for growth (Hgb-), but a minor population is able to do so (Hgb+). This minor population grows luxuriously on hemoglobin, expresses two outer membrane proteins of 42 kDa (HpuA) and 89 kDa (HpuB), and binds hemoglobin under iron-stressed conditions. In addition to the previously reported HpuB, we identified and characterized HpuA, which is encoded by the gene hpuA, located immediately upstream of hpuB. Expression of both proteins was found to be controlled at the translational level by frameshift mutations in a run of guanine residues within the hpuA sequence encoding the mature HpuA protein. The "on-phase" hemoglobin-utilizing variants contained 10 G's, while the "off-phase" variants contained 9 G's. Insertional hpuB mutants of FA19 Hgb+ and FA1090 Hgb+ no longer expressed HpuB but still produced HpuA. A polar insertional mutation of the upstream hpuA gene in FA1090 Hgb+ eliminated production of both HpuA and HpuB, whereas a nonpolar insertional mutant expressed HpuB only. Insertional mutagenesis of either hpuA or hpuB or both substantially decreased the hemoglobin binding ability of the FA1090 Hgb+ variant and prevented growth on hemoglobin plates. Therefore, both HpuA and HpuB were required for the utilization of hemoglobin for growth.

Amino Acid Sequence↗
PubMed1998

Lymantria dispar nucleopolyhedrovirus hrf-1 expands the larval host range of Autographa californica nucleopolyhedrovirus.

The gypsy moth (Lymantria dispar) is nonpermissive for Autographa californica nucleopolyhedrovirus (AcNPV) infection. We previously isolated a gene, host range factor 1 (hrf-1), from L. dispar nucleopolyhedrovirus that promotes AcNPV replication in Ld652Y cells, a nonpermissive L. dispar cell line (S. M. Thiem, X. Du, M. E. Quentin, and M. M. Berner, J. Virol. 70:2221-2229, 1996). In the present study, we investigated the ability of hrf-1 to alter the larval host range of AcNPV. Bioassays using recombinant AcNPV bearing hrf-1 were conducted with insect larvae by use of oral infection. AcNPV bearing hrf-1 was infectious for neonate L. dispar larvae, with a 50% lethal concentration of 1.2 x 10(5) polyhedral inclusion bodies/ml of diet, which is similar to that of wild-type AcNPV for permissive hosts. AcNPV can kill neonate L. dispar larvae at high doses, but it does not kill third-instar larvae. However, electron microscopy studies of AcNPV-inoculated third-instar larvae revealed virus replication in the midgut cells. PCR analyses indicated that the virus was AcNPV. These results suggest that the block for AcNPV infection of L. dispar larvae is its inability to spread systematically from primary infection sites in the midgut epithelium and that this barrier is leaky in neonates. hrf-1 allows AcNPV to overcome this barrier. AcNPV recombinants bearing hrf-1 were also significantly more infectious for Helicoverpa zea, a resistant species, suggesting that the blocks for AcNPV infection of L. dispar and H. zea larvae may be similar.

Animals↗
PubMed1998

Mortality attributable to cigarette smoking in Taiwan: a 12-year follow-up study.

BACKGROUND: Assessment of the impact of cigarette smoking on mortality helps to indicate the importance of tobacco control in a given country. OBJECTIVES: To examine the relative risk of dying from various diseases for cigarette smoking and to estimate annual mortality attributable to cigarette smoking in Taiwan. DESIGN: Prospective cohort study. SUBJECTS AND SETTING: A cohort of 14,397 male and female residents aged 40 years or older recruited from 12 townships and precincts in Taiwan from 1982 to 1986. Information on cigarette smoking was collected from each subject at local health centres through a standardised personal interview based on a structured questionnaire. They were followed up regularly to determine their vital status until 1994. MAIN OUTCOME MEASURES: Cox's proportional hazards regression models were used to derive relative risks of cause-specific mortality for current cigarette smokers compared with never-smokers, and to examine dose-response relationships between mortality from various causes and several measures of cigarette smoking (daily consumption, duration, age of initiation, and cumulative smoking in pack-years). RESULTS: A total of 2552 persons died during the study period. Among men, cigarette smoking was significantly associated with an increased risk of dying from all causes combined (relative risk (RR) = 1.3); cancer of all sites combined (RR = 1.5); cancers of the stomach (RR = 1.9), liver (RR = 2.2), and lung (RR = 3.7); ischaemic heart disease (RR = 1.8); other heart diseases (RR = 1.4); and chronic obstructive pulmonary disease (RR = 1.9). Among women, cigarette smoking was significantly associated with an increased risk of dying from all causes combined (RR = 1.8), cancer of the lung (RR = 3.6), and peptic ulcer (RR = 17.8). The estimated number of deaths attributable to cigarette smoking in Taiwan in 1994 was 8161 (13.9% of total deaths) for men and 1216 (3.3% of total deaths) for women. In the same year cigarette smoking caused 21.3% and 2.9% of cancer deaths in men and women, respectively, in Taiwan. CONCLUSIONS: Cigarette smoking has a striking impact on overall mortality and deaths from various causes in the Taiwanese population. Tobacco control should be established as the top priority in public health programmes in Taiwan.

Adult↗
PubMed1998

New developments in peritoneal dialysis solutions.

Existing peritoneal dialysis (PD) solutions were formulated mainly for the maintenance of fluid and electrolyte balance, correction of metabolic acidosis, and the removal of metabolic waste products. New solutions in development, and recently approved in some countries, are designed to improve ultrafiltration during long dwells (polyglucose or icodextrin solutions), to treat malnutrition (amino-acids solutions), and to improve peritoneal biocompatibility (bicarbonate-buffered solutions). Other new solutions under investigation are designed to address unmet clinical needs, including cardiovascular disease and sodium balance, through the use of a low-sodium PD solution; long-term peritoneal viability, through improvements in sterilization processes and the use of nonglucose osmotic agents; and PD adequacy, through the use of solution additives (such as glycosaminoglycans) and tailored PD prescriptions using APD. Future concepts for PD include remodeling of the peritoneum, perhaps using mesothelial gene therapy to introduce metabolic and anabolic machinery to remove or perpetually recycle metabolic wastes.

Amino Acids↗
PubMed1998

Hirayama disease: MR diagnosis.

We report the MR findings in two cases of Hirayama disease, a kind of cervical myelopathy related to flexion movements of the neck. In flexion MR studies, we can see the striking and pathognomonic picture of anterior shifting of posterior dura at the lower cervical spinal canal. In nonflexion studies, we find that asymmetric cord atrophy, especially at the lower cervical cord, though subtle, is highly suggestive of Hirayama disease. When it is seen, a flexion MR study is warranted to prove this diagnosis.

Adolescent↗
PubMed1998

T cell receptor gene V alpha and V beta usage in patients with rheumatoid arthritis in Taiwan.

To investigate the correlation of T cell receptor (TCR) genes to rheumatoid arthritis (RA) in Taiwan, synovial fluid and peripheral blood were examined simultaneously in 14 patients with RA, and peripheral blood only was examined in 15 healthy controls. RNA was extracted from T cell in synovial fluid and peripheral blood, and cDNA was synthesized using the reverse transcription method. Then, TCR-V alpha and V beta gene families were determined using the polymerase chain reaction and slot blot methods. The numbers of TCR-V alpha and V beta families, especially V beta, were decreased in rheumatoid synovial fluid compared with numbers found in the peripheral blood of the same RA patients. TCR-V beta 7 and V beta 8 could be found in the synovial fluid of all patients with positive HLA-DR4. However, there was no significant difference in the numbers of TCR-V alpha and V beta families in peripheral blood of RA patients and the peripheral blood of healthy controls. In conclusion, restricted heterogeneity of TCR-V gene, especially V beta, can be found in synovial fluid of patients with RA. TCR-V beta 7 and V beta 8 may be related to the pathogenesis of HLA-DR4 positive RA patients in Taiwan.

Arthritis, Rheumatoid↗
PubMed1998

Abnormal origin of the vertebral artery from the common carotid artery.

An abnormal origin of the vertebral artery from the common carotid artery (VA-CC) may occur on the right or left side with different embryonic mechanisms. We describe a patient with a double developmental anomaly, a right VA-CC and a right aortic arch. The rotation of the aortic arch caused a "twist" of the embryonic mechanisms of VA-CC and misdirected the differential diagnosis of the embryonic mechanisms at first glance. We discuss the pivotal points in differentiating the embryonic mechanisms of VA-CC.

Aortography↗
PubMed1998

Genetic analysis of interleukin-10 promoter region in patients with systemic lupus erythematosus in Taiwan.

Overproduction of interleukin-10 (IL-10) may play an important role in the development of systemic lupus erythematosus (SLE) or lupus nephritis. There is also a polymorphic dinucleotide repeat in the human IL-10 promoter region (IL-10PR). Our aim was to study whether or not the IL-10PR alleles contributed to the susceptibility to SLE or lupus nephritis. One hundred SLE patients and 103 healthy controls were studied for IL-10PR by PCR and electrophoretic analysis. The distribution of IL-10PR alleles, genotypes and the sum of both alleles (SBA) from different groups or subgroups were analyzed. SLE patients showed no difference in the distribution of IL-10PR alleles, genotypes and SBA, as compared to healthy controls. Lupus nephritis patients (N = 49) also showed no difference in IL-10PR alleles, genotypes and SBA, as compared to SLE patients without nephritis (N = 51). Of 49 lupus nephritis patients, ten developed end-stage renal disease (ESRD) and four of them were found to suffer from rapid progressive renal failure (RPRF). Patients with RPRF presented much smaller SBA than other ESRD patients (p = 0.005). Lupus nephritis patients carrying small SBA (< 18) suffered from a higher prevalence of RPRF than lupus nephritis patients without small SBA (50% V.S. 0%, p < 0.001, relative risk 82). Our data provide the first evidence of a strong association between IL-10PR and severe progression of lupus nephritis in human patients. In the future, a prospective genetic analysis of IL-10PR for patients with lupus nephritis is recommended. It might be helpful for physicians to identify the lupus nephritis subgroup with a high risk of developing RPRF early, because this might lead to a better therapy and prognosis for these patients.

Adult↗
PubMed1997

Characterization and purification of a lipoxygenase inhibitor in human epidermoid carcinoma A431 cells.

A lipoxygenase inhibitor in the cytosolic fraction of human epidermoid carcinoma A431 cells was characterized and purified. The cytosolic inhibitor lost the inhibitory activity upon heating at 75 degrees C for 15 min or pretreating with 1 mg/ml trypsin at 37 degrees C for 60 min. Cytosol, after dialysis, lost the inhibitory activity but its inhibitory activity recovered when 1 mM GSH was added to the dialysate. The inhibitory activity of cytosol was also abolished by treatment either with 1 mM iodoacetate at 4 degrees C for 1 h or with 0.5 mM H2O2. The pI of the inhibitor was approx. 7.0. In addition to 12-lipoxygenase, the inhibitor inhibited the activities of 5-lipoxygenase and fatty acid cyclo-oxygenase in a cell-free system. The inhibitor was purified by a series of column chromatographies using CM Sephadex C-50, Sephadex G-100 SF and Mono P columns. A major 22 kDa protein was obtained that was distinct from selenium-dependent glutathione peroxidase.

Arachidonic Acid↗