Biomedical subjects

C-S Chen

Publications and source records attributed to C-S Chen.

8 recordsLinked to original sources

PubMed2006

Beyond peroxisome proliferator-activated receptor gamma signaling: the multi-facets of the antitumor effect of thiazolidinediones.

Certain members of the thiazolidinedione (TZD) family of the peroxisome proliferator-activated receptor gamma (PPARgamma) agonists, such as troglitazone and ciglitazone, exhibit antitumor activities; however, the underlying mechanism remains inconclusive. Substantial evidence suggests that the antiproliferative effect of these TZD members in cancer cells is independent of PPARgamma activation. To discern the role of PPARgamma in the antitumor effects of TZDs, we have synthesized PPARgamma-inactive TZD analogs which, although devoid of PPARgamma activity, retain the ability to induce apoptosis with a potency equal to that of their parental TZDs in cancer cell lines with varying PPARgamma expression status. Mechanistic studies from this and other laboratories have further suggested that troglitazone and ciglitazone mediate antiproliferative effects through a complexity of PPARgamma-independent mechanisms. Evidence indicates that troglitazone and ciglitazone block BH3 domain-mediated interactions between the anti apoptotic Bcl-2 (B-cell leukemia/lymphoma 2) members Bcl-2/Bcl-xL and proapoptotic Bcl-2 members. Moreover, these TZDs facilitate the degradation of cyclin D1 and caspase-8-related FADD-like IL-l-converting enzyme (FLICE)-inhibitory protein through proteasome-mediated proteolysis, and down-regulate the gene expression of prostate-specific antigen gene expression by inhibiting androgen activation of the androgen response elements in the promoter region. More importantly, dissociation of the effects of TZDs on apoptosis from their original pharmacological activity (i.e. PPARgamma activation) provides a molecular basis for the exploitation of these compounds to develop different types of molecularly targeted anticancer agents. These TZD-derived novel therapeutic agents, alone or in combination with other anticancer drugs, have translational relevance in fostering effective strategies for cancer treatment.

Antineoplastic Agents↗

PubMed2005

Use of a fluorescent membrane probe to identify zooxanthellae in hospite among dissociated endoderm cell culture from coral.

Preparation of homogeneous endoderm cells and culture is a prerequisite to understanding the cellular and molecular mechanism of endosymbiosis in the cnidarian-dinoflagellate association. During the cell isolation from the stony coral Euphyllia glabrescens, various amounts of symbiotic endoderm cells were found to release their symbionts (Symbiodinium spp., or zooxanthellae in generic usage) into the culture. Due to the bulky occupation by zooxanthellae inside the endoderm cell, the symbiotic endoderm cells, or zooxanthellae in hospite, are difficult to be distinguished from released zooxanthellae by microscopic examination. We now report a method for this identification using a fluorescent analogue of sphingomyelin, N-[5-(5,7-dimethyl boron dipyrromethene difluoride)-1-pentanoyl]-D-erythro-sphingosylphosphorylcholine (C(5)-DMB-SM). Incubation of symbiotic endoderm cells with C(5)-DMB-SM-defatted bovine serum albumin (DF-BSA) complex results in bright fluorescent membrane staining. Nevertheless, the membrane staining of free-living or released zooxanthellae by this complex is significantly decreased or even diminished. This method has provided a fast and reliable assay to identify symbiotic endoderm cells and will greatly accelerate the progress of endosymbiosis research.

Animals↗

PubMed2005

Phase II randomized trial of vinorelbine and gemcitabine versus carboplatin and paclitaxel in advanced non-small-cell lung cancer.

BACKGROUND: The purpose of this study was to compare quality of life and overall toxicity in patients with advanced non-small-cell lung cancer (NSCLC) treated with vinorelbine-gemcitabine (VG) or carboplatin-paclitaxel (Taxol) (CP). PATIENTS AND METHODS: A total of 165 previously untreated patients were randomized to the two regimens. Quality of life was assessed by the Lung Cancer Symptom Scale (LCSS). Overall toxicity and secondary efficacy end points were evaluated by standard WHO criteria. RESULTS: There was no significant difference in overall quality of life between the two treatments. Neutropenia, thrombocytopenia, peripheral neuropathy, and alopecia, were more common in the CP arm, whereas constipation was more frequent in the VG arm. Response rates were 14.6% in the VG arm and 16.9% in the CP arm. Median survival times were 7.8 and 8.6 months, and 1 year survival rates were 38.4% and 31.9%, respectively. CONCLUSIONS: Patients treated with VG experienced lower toxicity, but overall quality of life was similar in both arms. Efficacy seemed comparable between VG and CP. Our study shows that VG is a viable alternative to platinum-based chemotherapy in patients with advanced NSCLC.

Adult↗

PubMed2005

Hypersensitivity to Forcipomyia taiwana (biting midge): clinical analysis and identification of major For t 1, For t 2 and For t 3 allergens.

BACKGROUND: Forcipomyia taiwana is a tiny, blood-sucking midge that cause intense pruritus and swelling in sensitive individuals. It is distributed island-wide in rural Taiwan and Southern China. OBJECTIVE: This study aimed to study the allergic immune responses and identify F. taiwana allergens. METHODS: Crude whole body F. taiwana extracts were prepared with phosphate-buffered saline. The specific IgE antibody was determined by enzyme-linked immunoassay and immunoblotting. Protein was analyzed by electrospray ionization tandem mass spectrometry. RESULTS: Among the 372 subjects that were exposed to F. taiwana bites, 179 (48%) reported an immediate skin reaction with/without delay reaction and 41(11.1%) reported a solely delay reaction. The skin of 21 subjects was tested with F. taiwana extract. Of these 21 subjects, 12 (57.1%) produced immediate skin reactions and contained high levels of specific IgE antibody against F. taiwana. Immunoblotting revealed that 11 allergenic components are able to bind specific IgE. Allergens of 22, 24, 35, 36, and 64 kDa bound 50, 50, 75, 66.7, and 75% of IgE-containing sera tested, respectively. Tryptic fragments of the 24, 35, 36, and 64 kDa allergens were analyzed by ESI-MS/MS. Selected tryptic peptides of 24, 35, and 36, and 64 kDa allergens exhibited significant sequence identity with triosephosphate isomerase of Anopheles merus,Tenebrio molitor,Ochlerotatus togoi, and Chrysops vittatus, fructose 1,6-bisphosphate aldolase of Antheraea yamamai and Homalodisca coagulata, and a slow muscle myosin S1 heavy chain of Homarusamericanus and a protein with unknown function from A. gambiae, respectively. The 35 and 36 kDa proteins may represent different isoforms of the fructose 1,6-bisphosphate aldolase. CONCLUSION: We conclude that immediate reaction to F. taiwana bites is IgE mediated and the 24 (For t 1), 35 (For t 2), and 64 kDa (For t 3) proteins are candidates for major F. taiwana allergens. Further studies are needed to confirm these allergens.

Adolescent↗

PubMed2003

Technical quality of root canal treatment in Taiwan.

AIM: To evaluate the current technical quality of root canal treatment (RCT) in Taiwan. METHODOLOGY: A total of 1085 RCT cases, randomly selected from a large sample and representative of the Taiwanese population from April to September 2000, were evaluated by eight endodontic specialists. The qualitative evaluation of RCT cases was based on two variables: length of the root filling and density of the obturation. A root canal with both adequate filling length (the apical termination of the root filling within 2 mm of the radiographic apex) and complete obturation (no lateral or apical canal lumen visible in the apical one-third of the root canal) was defined as having good-quality endodontic work (GQEW). A tooth was defined as having a GQEW when all its canals were categorized as GQEW. RESULTS: From a total of 1867 root canals, overfilling occurred in 235 (12.6%), adequate filling length in 1152 (61.7%), underfilling in 466 (25.0%) and no filling in 12 (0.6%). Of the 1867 root canals, 710 (38.0%) demonstrated complete obturation and 1157 (62%) demonstrated incomplete obturation. GQEW was found in 650 (34.8%) root canals and 329 (30.3%) teeth. The percentage of teeth with GQEW in hospital cases (38.1%) was significantly greater (P < 0.001) than that in private clinic cases (24.3%). In addition, the frequency of teeth with GQEW in the anterior teeth (40.4%) or in the premolars (33%) was significantly greater (P < 0.001) than that in the molars (18.4%). CONCLUSIONS: Approximately 70% of the teeth receiving RCT in Taiwan were either of inadequate filling length or sealing density.

Bicuspid↗

PubMed2002

Hyperbaric oxygen attenuates lipopolysaccharide-induced acute lung injury.

OBJECTIVES: To study the effect of hyperbaric oxygen therapy in alleviating acute lung injury induced by lipopolysaccharide (LPS) in rats. DESIGN AND INTERVENTIONS: The rats received an intraperitoneal injection of LPS (15 mg/kg). Animals were either breathing air at 1 ATA or subjected to hyperbaric oxygen (HBO(2)) therapy. The HBO(2) therapy was carried out in a hyperbaric chamber at a pressure of 3 ATA for 90 min. In another two groups, LPS-treated rats also received intraperitoneal injection of N(omega)-nitro-L-arginine (LNAME, 25 mg/kg) or L-N(6)-(iminoethyl)lysine (LNIL, 10 ml/kg). Another two groups of LPS-treated rats were subjected to HBO(2) exposure after the injection of L-NAME or L-NIL. MEASUREMENTS AND MAIN RESULTS: The bronchoalveolar lavage (BAL) was done into the left lung at 7.5 h after intraperitoneal injection of LPS. Parts of the right lung were excised for myeloperoxidase measurement, whereas the rest was collected for wet/dry ratio determination. LPS significantly increased the nitrite/nitrate (NO(x)(-)) concentration (34.4+/-15.7 vs 4.5+/-3.1 microM), LDH activity (66+/-17 vs 46+/-15 mAbs/min), and protein concentration (373+/-119 vs 180+/-90 mg/l) in the BAL fluid. Treatment with HBO(2) immediately after the injection of LPS enhanced the increase of NO(x)(-) production, but reduced the LDH and protein in BAL fluid to the control levels. Pretreatment with either L-NAME or L-NIL abolished the increase of NO(x)(-) in the BAL fluid and further elevated the LDH level and protein concentration. CONCLUSION: Our results suggested that HBO(2) alleviates the LPS-induced acute lung injury, which may be related to the enhancement of nitric oxide production.

Analysis of Variance↗

PubMed2002

Fracture in mode I using a conserved phase-field model.

We present a continuum phase-field model of crack propagation. It includes a phase-field that is proportional to the mass density and a displacement field that is governed by linear elastic theory. Generic macroscopic crack growth laws emerge naturally from this model. In contrast to classical continuum fracture mechanics simulations, our model avoids numerical front tracking. The added phase-field smooths the sharp interface, enabling us to use equations of motion for the material (grounded in basic physical principles) rather than for the interface (which often are deduced from complicated theories or empirical observations). The interface dynamics thus emerges naturally. In this paper, we look at stationary solutions of the model, mode I fracture, and also discuss numerical issues. We find that the Griffith's threshold underestimates the critical value at which our system fractures due to long wavelength modes excited by the fracture process.

Journal Article↗

PubMed2002

Increase of mitochondrial DNA in blood cells of patients with Leber's hereditary optic neuropathy with 11778 mutation.

AIMS: To investigate the change of mitochondrial DNA (mtDNA) content in Leber's hereditary optic neuropathy (LHON) with 11778 mutation. METHODS: Mitochondrial DNA content in 27 LHON patients with 11778 mutation, 26 asymptomatic maternal relatives, and 23 normal controls was measured using a competitive polymerase chain reaction (PCR) method. RESULTS: The mean relative content of mtDNA (with respect to the beta actin gene) in LHON patients, asymptomatic maternal relatives, and normal controls was 245.5 (162.3), 238.2 (118.4), and 156.5 (61.6), respectively. There was a statistically significant difference between patients and controls and between relatives and controls. However, no statistically significant difference between patients and unaffected relatives was found. There was no statistically significant difference in the relative content of mtDNA between all males and females carrying 11778 mtDNA mutation CONCLUSION: The results suggest that the increase in mtDNA content in LHON patients with 11778 mtDNA mutation may be due to a compensatory effect for respiratory chain defects of mitochondria. However, the increase of mtDNA content is the result rather than the cause of defective mtDNA. It still cannot explain the pathogenesis of LHON.

Adolescent↗