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Biomedical subjects

S C Chen

Publications and source records attributed to S C Chen.

At least 73 records · Page 4Linked to original sources
PubMed2001

The study of Central Taiwan particles concentration variations during earthquake period.

Ambient particle concentration was taken on the traffic sampling site over the Chung-Chi Road over the bridge (CCROB) in front of Hungkuang Institute of Technology (HKIT). The sampling time was from August 1999 to December 1999. During the sampling period, Taiwan's biggest earthquake in more than a century registered 7.3 on the Richter scale (Taiwan Chi-Chi Earthquake). Besides, there are more than 20,000 aftershocks following the Taiwan Chi-Chi Earthquake within 3 months. Thus, the mass concentration of particles with aerodynamic diameters smaller than 2.5 microm (PM2.5) and PM2.5-10 was also collected then compared with the total mass concentration of suspended particles (TSP) in this study. The average TSP, PM2.5-10, and PM2.5 concentrations are 106, 24.6, and 58.0 microg/m3, respectively, after the Taiwan Chi-Chi Earthquake. The average TSP concentrations before and after Taiwan Chi-Chi Earthquake were 69.6 and 127 microg/ m3, respectively. In addition, statistical analysis of the PM10 data from this study and EPA in 1999 yielded a Tstatistic of 0.147, which is smaller than t(0.975,18) = 2.101. It is indicated that there was no significant difference. So, the PM10 concentrations measured after Taiwan Chi-Chi Earthquake in this study were also greater than those data previously obtained from Taiwan EPA in the same region of this area. The relationships between TSP, PM10, PM2.5-10, and PM2.5 particle concentrations and wind speed (R2) are .77, .59, .58, .58, respectively. And the ratios of PM2.5/PM25-10, PM2.5/PM10, and PM10/TSP are 221%, 67.2%, 58.0%, respectively. The average ratios of PM2.5/PM2.5-10 and PM2.5/PM10 increase by about 120% and 17%. It indicated that the fine-particles concentration increases compared to the coarse-particles concentration after 921 Taiwan Chi-Chi Earthquake. And the proposed reasons are that local motor vehicle emissions combined the fine particles transported from the Chi-Chi epicenter. More importantly, the wind direction was mainly blown from southeastern part. These two main factors enhance the fine-particles concentration in this area.

Air Pollutants↗
PubMed2001

GB virus C/hepatitis G virus infection in chronic hepatitis C patients with and without interferon-alpha therapy.

GB virus C/hepatitis G virus (GBV-C/HGV) RNA, detected by polymerase chain reaction, and antibodies to the GBV-C/HGV envelope protein (anti-E2), detected by an enzyme-linked immunosorbent assay, were used to evaluate both the impact of GBV-C/HGV on the coexistent hepatitis C virus (HCV) infection and the course of GBV-C/HGV infection in chronic hepatitis C patients with and without interferon-alpha (IFN-alpha) treatment. Of the 162 chronic hepatitis C patients treated with INF-alpha, 17.9% were GBV-C/HGV RNA-positive and 18.5% anti-E2-positive (total exposure, 35.2%). Neither present nor past GBV-C/HGV infection had impact on the clinical features, HCV virological characteristics and response to IFN-alpha treatment in chronic hepatitis C patients. Among patients with ongoing HCV/GBV-C/HGV coinfection, 20.7% (6/29) in IFN-alpha-treated patients lost GBV-C/HGV RNA concomitant with anti-E2 seropositivity, which was significantly higher than 4.8% (2/42) in patients without INF-alpha treatment (P<0.05). Based on multivariate analyses, the significant factors associated with clearance of GBV-C/HGV viremia combined with anti-E2 seropositivity were baseline anti-E2 seropositivity and IFN-alpha treatment. In summary, GBV-C/HGV did not alter the course of coexistent HCV. IFN-alpha treatment was effective in some patients against GBV-C/HGV and might facilitate anti-E2 seroconversion in chronic hepatitis C patients with GBV-C/HGV viremia.

Adolescent↗
PubMed2001

Color Doppler ultrasound in breast carcinomas: relationship with hormone receptors, DNA ploidy, S-phase fraction, and histopathology.

Data on 368 patients with breast carcinomas measuring < or = 5 cm were analyzed to study the relationship between the prognostic factors and the flow indices measured by color Doppler ultrasound (US). Vascularity was detected by color Doppler US in 348 (94.6%) of the 368 breast tumors. Tumors without vascularity were significantly (p = 0.0001) smaller than the tumors with vascularity. There was a correlation between Vmax and tumor size. Postmenopausal women had greater values of RI, PI, and V(max). Tumors larger than 2 cm had significantly greater RI, V(max) and number of vessels as compared with the tumors smaller than 2 cm. RI was significantly greater in the nondiploid tumors than in the diploid tumors. RI > or = 0.7 was significantly associated with nondiploid carcinomas and SPF > or = 7%. Tumor size and Vmax significantly predicted axillary lymph node metastases.

Adult↗
PubMed2001

Clinical spectrum of restrictive cardiomyopathy in children.

We reviewed the clinical spectrum and possible prognostic factors in 14 children with restrictive cardiomyopathy. The patients were not homogeneous in clinical presentation or morphology. The mortality rate was high: 21.4% at 1 year and 50% at 2 years after presentation. Younger patients with respiratory symptoms, thromboembolism, increased cardiothoracic ratio on chest radiogram or patients with endocardial fibroelastosis appear to have a worse prognosis and orthotopic cardiac transplantation may be indicated.

Adolescent↗
PubMed2001

Health status of mothers of adults with intellectual disability.

A cross-sectional survey was conducted to describe the health of mothers of adults with intellectual disability (ID), and the influence of the mother's and her adult child's characteristics on her health. The sample consisted of 108 mothers divided into mid-life and later-life groups. Four service agencies mailed SF-36 forms and demographic questionnaires to their clients. The return rate from primary caregivers was 70%. The physical and the mental components of health of both groups of mothers were found to be similar to or better than those of their counterparts in the US national norms. Arthritis was found to influence the physical health of both groups of mothers. Employment was found to influence physical health of the mid-life mothers, while family income was found to influence mental health of the later-life mothers. The characteristics of adults with ID did not influence the mothers' health significantly. Mothers' caregiving for their adult children with ID might not be as detrimental to the mid-life mothers' physical component of health as it might be to the later-life mothers. Further studies are needed.

Adult↗
PubMed2001

Extracellular phospholipase activity is a virulence factor for Cryptococcus neoformans.

The human pathogenic fungus Cryptococcus neoformans secretes a phospholipase enzyme that demonstrates phospholipase B (PLB), lysophospholipase hydrolase and lysophospholipase transacylase activities. This enzyme has been postulated to be a cryptococcal virulence factor. We cloned a phospholipase-encoding gene (PLB1) from C. neoformans and constructed plb1 mutants using targeted gene disruption. All three enzyme activities were markedly reduced in the mutants compared with the wild-type parent. The plb1 strains did not have any defects in the known cryptococcal virulence phenotypes of growth at 37 degrees C, capsule formation, laccase activity and urease activity. The plb1 strains were reconstituted using the wild-type locus and this resulted in restoration of all extracellular PLB activities. In vivo testing demonstrated that the plb1 strain was significantly less virulent than the control strains in both the mouse inhalational model and the rabbit meningitis model. We also found that the plb1 strain exhibited a growth defect in a macrophage-like cell line. These data demonstrate that secretory phospholipase is a virulence factor for C. neoformans.

Acyltransferases↗
PubMed2001

Influence of hepatitis C virus on the profiles of patients with chronic hepatitis B virus infection.

BACKGROUND: Hepatitis B virus (HBV) and hepatitis C virus (HCV) are the most common causes of chronic liver disease, cirrhosis and hepatocellular carcinoma. The influence of HCV infection on the clinicopathological and virological profiles of chronic HBV infection was investigated. METHODS: A total of 100 chronic HBV carriers with histopathological diagnoses by liver biopsy were studied. Hepatitis B e antigen (HBeAg) and anti-HCV antibody were tested. Serum HCV-RNA was detected by using a nested reverse transcription-PCR assay. A branched DNA (bDNA) assay was used to detect HBV-DNA and quantitate the serum levels. RESULTS: Eighteen (18%) of 100 patients were positive for anti-HCV and HCV-RNA. Patients with concurrent HCV and HBV infection were significantly older than those without HCV infection (P < 0.05). The positive rates of HBeAg and HBV-DNA as well as the serum levels of HBV-DNA in patients with concurrent HCV and HBV infection were significantly lower than those without concurrent HCV and HBV infection (P < 0.01, P < 0.05, and P < 0.001, respectively). By using multivariate analysis, the factors of seroconversion of HBeAg and decreasing level of HBV-DNA were significantly correlated to concurrent HCV and HBV infection in chronic HBV carriers. The factors of increasing age and concurrent HCV and HBV infection were significantly correlated to seroconversion of HBeAg. CONCLUSIONS: The concurrent HCV and HBV infection in chronic HBV carriers might result in a suppression of HBV replication that presented with a lower level of serum HBV-DNA and HBeAg seroconversion. Nevertheless, neither more obvious increase in biochemical parameters nor histopathological progression to more advanced liver diseases was observed.

Adult↗
PubMed2001

Tubulointerstitial nephritis associated with a novel mitochondrial point mutation.

BACKGROUND: Nephropathy caused by mitochondrial disorders is a relatively newly recognized disease. Only a few cases have been reported in the literature, and most of them are proximal tubulopathy-presenting Fanconi syndrome. Here we report on a novel mutation in two familial cases of tubulointerstitial nephropathy associated with concentrating defect. METHODS: Renal biopsy specimens were examined by light microscopy and electron microscopy. Mitochondrial genomic DNA isolated from renal biopsy specimens was amplified by polymerase chain reaction (PCR) and sequenced in its entirety. The DNA sequences were analyzed by (1) comparing with the Anderson et al's mitochondrial sequences; (2) comparing with DNA sequences obtained from 97 human controls, including both healthy individuals and patients with renal diseases; and (3) comparing with the counterparts in 90 different species. RESULTS: Dismorphic mitochondria with occasional intramitochondrial inclusions were found in the renal tubular epithelial cells. A novel mitochondrial point mutation was identified at the position 608, that is, the distal end of the anticodon stem of the tRNA(Phe) molecule. The A to G substitution at this position was not observed in 97 human controls and was found to be highly conserved in evolution. CONCLUSIONS: We have identified an A608G mutation of mitochondrial genome in two cases whose presentation include tubulointerstitial nephritis and stroke.

Animals↗
PubMed2001

The serological and molecular epidemiology of GB virus C/hepatitis G virus infection in a hepatitis C and B endemic area.

OBJECTIVES: To investigate the serological and molecular characteristics of GB virus C/hepatitis G virus (GBV-C/HGV) infection in the hepatitis C virus (HCV)/hepatitis B virus (HBV)-endemic areas in Taiwan. METHODS: Sera from 200 residents from Masago, an HCV/HBV-endemic community in Taiwan, and 400 blood donors were tested for GBV-C/HGV RNA by using nested reverse transcription-polymerase chain reaction and for antibodies to GBV-C/HGV E2-protein (anti-E2) by an enzyme-linked immunosorbent assay. Phylogenetic analysis of GBV-C/HGV was performed. RESULTS: The prevalence of GBV-C/HGV viraemia, anti-E2 and GBV-C/HGV exposure among residents of Masago was significantly higher than that among donors (17.0%, 25.5% and 39.5% vs. 3.3%, 7.5% and 10.3%, respectively; all P < 0.0001). In Masago, the prevalence of GBV-C/HGV exposure was significantly higher in residents exposed to HCV than in those without HCV exposure (45.8% vs. 24.1%;P< 0.005). Based on multivariate analyses, HCV viraemia was the only significant factor associated with elevated levels of alanine aminotransferase in Masago. Phylogenetic analysis showed all 34 GBV-C/HGV isolates from Masago clustered within genotype 3. CONCLUSIONS: GBV-C/HGV was highly prevalent in Masago, an HCV/HBV-endemic community in Taiwan. HCV viraemia played the most important clinical hepatopathic role in the area. Infections with other hepatitis viruses did not influence the anti-E2 seroconversion from GBV-C/HGV infections.

Adult↗
PubMed2001

Leaf senescence in rice plants: cloning and characterization of senescence up-regulated genes.

To identify senescence-associated genes (SAGs) in rice leaves, senescence was induced by transferring rice seedlings into darkness. Senescence up-regulated cDNAs were obtained by PCR-based subtractive hybridization. Among 14 SAG clones characterized, 11 were found to be associated with both dark-induced and natural leaf senescence. Three clones were associated only with dark-induced leaf senescence. The possible physiological roles of these SAGs during rice leaf senescence are discussed.

Cloning, Molecular↗
PubMed2001

Methanofollis aquaemaris sp. nov., a methanogen isolated from an aquaculture fish pond.

A novel methanogen, designated strain N2F9704T, was isolated from an aquaculture fish pond near Wang-gong, Taiwan. The cells were irregular cocci, non-motile, 1.2-2.0 microm in diameter and stained gram-negative. Cells of strain N2F9704T lysed easily by SDS treatment (0.1 g l(-1)) and the S-layer protein had an Mr of 137000. The catabolic substrates used included formate and H2+CO2, but not acetate, methanol, trimethylamine or secondary alcohols. The optimal growth parameters for strain N2F9704T were pH 6.5, 37 degrees C with 0.5% NaCl. Trace amounts of tungstate not only promoted growth but also extended the range of growth conditions. Analysis of the 16S rDNA sequence revealed a phylogenetic relationship to Methanofollis species and the name Methanofollis aquaemaris sp. nov. is therefore proposed for strain N2F9704T (= OCM 746T = CCRC 16166T). Additionally, the strain was infected with a novel coccus-shaped, enveloped virus with a diameter of 200 nm.

Anti-Bacterial Agents↗
PubMed2001

Treatment of canine leproid granuloma syndrome: preliminary findings in seven dogs.

OBJECTIVE: To determine effective treatment strategies for patients with refractory canine leproid granuloma syndrome. DESIGN: Multi-institutional retrospective/prospective case series using client-owned dogs. PROCEDURE: Seven dogs (four Boxers, one Dobermann, one Bullmastiff and one Bullmastiff cross-bred; ages 3 to 11 years) with leproid granulomas were treated successfully using a variety of treatment regimens. These cases were recruited because: lesions were either widely distributed over the dog; progressive, despite routine therapy, or were associated with particularly disfiguring lesions. The treatment regimen evolved during the course of the clinical study. RESULTS: Combination therapy using rifampicin (5 to 15 mg/kg p.o., every 24 h) and clarithromycin (8 to 24 mg/kg p.o. daily; dose divided every 8 or every 12 h) was used most frequently and proved to be effective and free from side effects. Total daily doses of clarithromycin in excess of 14 mg/kg were considered optimal and long treatment courses, in the order of 1 to 3 months, were used. Combination therapy using rifampicin (25 mg/kg; that is, higher than the recommended dose) and clofazimine was effective in one case, but resulted in hepatotoxicity. A topical formulation of clofazimine in petroleum jelly was used as an adjunct to oral rifampicin and doxycycline in another patient treated successfully. CONCLUSION: Based on our evolving clinical experience, a combination of rifampicin (10 to 15 mg/kg p.o., every 24 h) and clarithromycin (15 to 25 mg/kg p.o. total daily dose; given divided every 8 to 12 h) is currently recommended for treating severe or refractory cases of canine leproid granuloma syndrome. Treatment should be continued (typically for 4 to 8 weeks) until lesions are substantially reduced in size and ideally until lesions have resolved completely. A topical formulation, containing clofazimine in petroleum jelly may be used as an adjunct to systemic drug therapy. Further work is required to determine the most cost effective treatment regimen for this condition.

Animals↗
PubMed2001

Generation and analysis of mice lacking the chemokine fractalkine.

Fractalkine (CX(3)CL1) is the first described chemokine that can exist either as a soluble protein or as a membrane-bound molecule. Both forms of fractalkine can mediate adhesion of cells expressing its receptor, CX(3)CR1. This activity, together with its expression on endothelial cells, suggests that fractalkine might mediate adhesion of leukocytes to the endothelium during inflammation. Fractalkine is also highly expressed in neurons, and its receptor, CX(3)CR1, is expressed on glial cells. To determine the biologic role of fractalkine, we used targeted gene disruption to generate fractalkine-deficient mice. These mice did not exhibit overt behavioral abnormalities, and histologic analysis of their brains did not reveal any gross changes compared to wild-type mice. In addition, these mice had normal hematologic profiles except for a decrease in the number of blood leukocytes expressing the cell surface marker F4/80. The cellular composition of their lymph nodes did not differ significantly from that of wild-type mice. Similarly, the responses of fractalkine(-/-) mice to a variety of inflammatory stimuli were indistinguishable from those of wild-type mice.

Animals↗
PubMed2001

Tumorigenesis induced by the HHV8-encoded chemokine receptor requires ligand modulation of high constitutive activity.

ORF74 (or KSHV-vGPCR) is a highly constitutively active G protein-coupled receptor encoded by HHV8 that is regulated both positively and negatively by endogenous chemokines. When expressed in transgenic mice, this chemokine receptor induces an angioproliferative disease closely resembling Kaposi sarcoma (KS). Here we demonstrate that several lines of mice carrying mutated receptors deficient in either constitutive activity or chemokine regulation fail to develop KS-like disease. In addition, animals expressing a receptor that preserves chemokine binding and constitutive activity but that does not respond to agonist stimulation have a much lower incidence of angiogenic lesions and tumors. These results indicate that induction of the KS-like disease in transgenic mice by ORF74 requires not only high constitutive signaling activity but also modulation of this activity by endogenous chemokines.

Amino Acid Sequence↗
PubMed2001

Hepatic MR imaging using ferumoxides: prospective evaluation with surgical and intraoperative sonographic confirmation in 25 cases.

OBJECTIVE: The purpose of our study was to evaluate the sensitivity and accuracy of ferumoxides-enhanced MR imaging in comparison with surgery and intraoperative sonography. SUBJECTS AND METHODS: We prospectively evaluated 25 consecutive studies in 24 patients who underwent ferumoxides-enhanced hepatic MR imaging before surgery and intraoperative sonography. Both 1.5-T scanners (13 cases) and 0.2-T scanners (12 cases) were used. Turbo spin-echo T2-weighted sequences were performed before and after the administration of ferumoxides and the images were compared. Lesions were classified as solid or nonsolid and tabulated on standard liver maps. The liver maps from MR imaging were compared with those from surgery and intraoperative sonography. For lesions greater than 1 cm, the regions of interest were measured and contrast-to-noise ratio was calculated. RESULTS: Of 93 solid lesions found at surgery, 69 were seen on unenhanced MR imaging (sensitivity, 74.2%) and 87 were seen on ferumoxides-enhanced MR imaging (sensitivity, 93.5%) (p < 0.05). Of the seven benign lesions (five cysts, two hemangiomas) found at surgery, all were correctly identified as benign on MR imaging. Two lesions identified as solid before surgery were not found at surgery. Mean lesion contrast-to-noise ratio for the unenhanced scans was 22.9 and 34.5 (p < 0.001) for the ferumoxides-enhanced scans. Subanalysis of 1.5- and 0.2-T MR imaging revealed similar results with significant (p < 0.05) increases in sensitivity for both. The average size of the lesions missed before surgery was 0.7 cm. CONCLUSION: Turbo spin-echo T2-weighted ferumoxides-enhanced MR imaging at either 1.5 or 0.2 T has value in preoperative liver assessment.

Adult↗