PubMed Health⌕ Search

Biomedical subjects

Chien-Yuan Chen

Publications and source records attributed to Chien-Yuan Chen.

14 recordsLinked to original sources
PubMed2006

A web-based decision support system for slopeland hazard warning.

A WebGIS decision support system for slopeland hazard warning based on real-time monitored rainfall is introduced herein. This paper presents its framework, database, processes of setting up the threshold line for debris flow triggering and the calculation algorithm implemented in the system. The web-based GIS via the Microsoft Internet Explorer is designed for analysis of areas prone to debris flows outburst and landslides during torrential rain. Its function is to provide suggestions to commander for immediate response to the possibility of slopeland hazards, and determine if pre-evacuation is necessary. The defining characteristics of the internet-based decision support system is not to automatically show the dangerous areas but acts as part of the decision process via information collection to help experts judge the prone debris flow creeks and the tendency of landslides initiation. The combination with real-time rainfall estimation by the QPESUMS radar system is suggested for further enhancement.

Decision Support Techniques↗
PubMed2006

Clinical implications of SOCS1 methylation in myelodysplastic syndrome.

The suppressor of cytokine signalling-1 (SOCS1) protein is a tumour suppressor. Hypermethylation of SOCS1 gene, resulting in transcriptional silencing, is suggested to play an important role in cancer development. We sought to characterise SOCS1 methylation in primary myelodysplastic syndrome (MDS) and clarify its clinical implications. The methylation status of SOCS1 was analysed by methylation-specific polymerase chain reaction in 114 patients with primary MDS and serial studies were performed in 29 of them. SOCS1 methylation occurred in 54 patients (47.4%), and was more frequent in patients with high-risk MDS than in those with low-risk (52.6% vs. 25.8%, P = 0.011). SOCS1 methylation was closely associated with NRAS mutation (P = 0.010) and inversely associated with good-risk karyotype (P = 0.021). With a median follow-up of 17 months (range: 1-231 months), two patients acquired SOCS1 methylation during disease progression. In two patients, SOCS1 methylation present at diagnosis, disappeared after haematopoietic stem cell transplantation. Patients with SOCS1 methylation had a higher cumulative risk of leukaemic transformation than those without (55.8% vs. 27.7% at 3 years, P = 0.004). This difference remained significant within the subgroup of patients with high-risk MDS (67.3% vs. 45.1% at 3 years, P = 0.045). This is the first report to demonstrate the clinical relevance of SOCS1 methylation in MDS. It may play an important role in the pathogenesis of MDS, especially among patients with high-risk subtypes.

Adolescent↗
PubMed2006

Treatment outcomes in patients receiving conventional amphotericin B therapy: a prospective multicentre study in Taiwan.

OBJECTIVES: To evaluate treatment outcomes and healthcare resource use with conventional amphotericin B therapy for invasive fungal infections (IFIs). PATIENTS AND METHODS: A prospective observational study in hospitalized adult patients receiving amphotericin B treatment was undertaken at four hospitals in Taiwan. Patients were observed from the start of therapy to hospital discharge. RESULTS: A total of 108 patients (October 2000 to April 2002) were included in the study. Proven or probable IFIs as defined by the EORTC/MSG criteria were the reasons for the initiation of amphotericin B in 35.2% of the sample. A total of 24.1% patients developed nephrotoxicity (NT) (defined as a 50% increase in the baseline serum creatinine and achieving a peak of at least 2.0 mg/dL). Treatment of proven/probable IFIs [odds ratio (OR) = 4.16, 95% confidence interval (CI) = 1.61-10.75] was a significant predictor of the development of NT. The in-hospital mortality rate was 38.0%. Proven/probable IFIs (OR = 6.93, 95% CI = 2.62-18.29) and the development of NT (OR = 3.68, 95% CI = 1.22-11.04) were independent predictors of in-hospital mortality. For patients alive at discharge, those with NT had a trend of longer hospital stay compared with patients who had not developed NT (mean, 49.3 +/- 18.2 versus 29.3 +/- 22.3 days, P = 0.069). For patients who died, those who had developed NT died sooner (15.5 +/- 16.7 versus 33. 8 +/- 26.9 days, P = 0.0004). CONCLUSIONS: NT was associated with accelerated mortality and increased hospital stay for patients who survived. Using amphotericin B carefully or the use of antifungal agents with less potential for NT might improve patient outcomes.

Adult↗
PubMed2006

Nucleophosmin mutations in de novo acute myeloid leukemia: the age-dependent incidences and the stability during disease evolution.

Nucleophosmin (NPM) mutations have been found in a significant proportion of adults with de novo acute myeloid leukemia (AML), especially in those of a normal karyotype. These results provide a basis for studies of the pathogenesis in this specific subgroup of AML. In this study, NPM mutations were analyzed in 173 Chinese patients of de novo AML, including adults and children. We found that NPM mutations were present in 19.1% of the overall population and 40.3% of those with a normal karyotype. Adults had a significantly higher incidence of NPM mutations than children [32 of 126 (25.4%) versus 1 of 47 (2.1%), P < 0.001]. NPM mutations were closely associated with normal karyotype (P < 0.001) and internal tandem duplication of FLT3 (P = 0.002), but negatively associated with CEBPA mutations (P = 0.032) and expression of CD34 (P < 0.001) and HLA-DR (P = 0.003). Serial analyses of NPM mutations showed the mutation disappeared at complete remission, but the same mutation reappeared at relapse, except for one who lost the mutation at the second relapse, when new cytogenetic abnormalities emerged. None acquired novel mutations during the follow-up period. In conclusion, NPM mutations occur in an age-dependent fashion. Moreover, the findings that NPM mutations are stable during disease evolution and closely associated with disease status make it a potential marker for monitoring minimal residual disease.

Acute Disease↗
PubMed2006

Risk indicators for early childhood caries in Taiwan.

OBJECTIVES: The purpose of this study was to investigate the prevalence, patterns, and etiological factors for caries in children. METHODS: A total of 981 children less than 6 years of age were examined using a dental mirror and explorer. A parent or a caregiver was asked to complete a questionnaire regarding information about the child, the household, and oral hygiene. The prevalence and patterns of dental caries including pit and fissure caries, facial/lingual caries, molar proximal caries, and facial/lingual molar proximal lesions, were analyzed. Each child was classified as caries free or as having one of these four caries patterns. RESULTS: Weighted mean deft was 0.14 at age 2, 2.58 at age 3, 4.41 at age 4, 6.94 at age 5, and 7.31 at age 6. Weighted mean defs was 4.71, 8.44, 16.45 and 18.64 at ages 3, 4, 5, and 6, respectively. By age 2, 5.09% of children had caries. By age 6, 89.38% of children had caries. By age 3, 30.02% of children fitted the facial and lingual pattern of caries and by age 6, 52.90% of children fit the 'facial-lingual and molar-proximal' pattern, indicating extensive smooth surface decay. The total prevalence of early childhood caries was 56%. Multivariate-adjusted odds ratios identified factors associated with the high caries experience of the young children and found caries was strongly associated with the lack of proper tooth brushing and high consumption of sweets. Higher caries scores were also associated with areas of low urbanization. CONCLUSIONS: The findings of this survey indicated a high level of untreated caries among children in Taiwan.

Age Factors↗
PubMed2005

Characterization of CEBPA mutations in acute myeloid leukemia: most patients with CEBPA mutations have biallelic mutations and show a distinct immunophenotype of the leukemic cells.

PURPOSE: The transcription factor CCAAT/enhancer binding protein alpha, encoded by the CEBPA, is crucial for the differentiation of immature granulocytes. Mutation of the CEBPA may play an important role in leukemogenesis and prognosis. We sought to characterize the CEBPA mutation in acute myeloid leukemia (AML) and to clarify if there is a distinct immunophenotype for leukemic cells with the mutation. EXPERIMENT DESIGN: One hundred and four patients with de novo AML were evaluated for the CEBPA mutation and immunophenotype of the leukemic cells. RESULTS: Twenty-two distinct mutations were identified in 16 (15%) of 104 AML patients. Fourteen patients had biallelic mutations, mostly involving both the NH(2)-terminal TAD1 region and the COOH-terminal basic leucine zipper domain (bZIP). The mutations in the bZIP region were always tandem duplications and were located at hot-spot regions for topoisomerase II sites. Sequential study of the CEBPA mutations showed that the mutations disappeared at complete remission but the same mutations reappeared at relapse. None of the patients developed novel mutations during the follow-up period. Patients with CEBPA mutations had significantly higher incidences of CD7 (73%), CD15 (100%), CD34 (93%), and HLA-DR (93%) expression on the leukemic cells. CONCLUSION: These data revealed that most AML with CEBPA mutations were associated with an immunophenotype of HLA-DR(+)CD7(+)CD13(+)CD14(-)CD15(+)CD33(+)CD34(+). The close relationship of CEBPA mutations with the leukemia status of the patients and the concordance of mutation in presenting and relapse samples implicate the CEBPA mutation as a potential marker for monitoring minimal residue disease.

Acute Disease↗
PubMed2004

Development of an immunosensor for human ferritin, a nonspecific tumor marker, based on surface plasmon resonance.

A direct human ferritin immunosensor was developed using anti-human ferritin monoclonal antibodies (MAbs) immobilized on the gold surface of a self-assembled surface plasmon resonance (SPR) apparatus. A kind of self-assembled monolayer (SAM) prepared by cystamine-glutaraldehyde method was applied to immobilize the MAbs. The reusability of the sensor chip adopting the SAM was found to be better than the other immobilization methods including adsorption, protein A, concanavalin A method. Ten cycles of measurements could be performed on the same chip regenerated with a 0.1M HCl solution. A linear relationship existed between the angle shifts (millidegrees) and the log values of ferritin concentrations in the range from 0.2 to 200 ng/ml in buffer and human serum. When used for 15 days, the angle shifts were all >95% of those on the response at the first day. A 10 M NaOH solution was used for clearing nonspecific binding in human serum. Correlation coefficient was 0.991 between this SPR method and chemiluminescent immunoassay for determination of ferritin in clinical human serum samples. The SPR sensor offers advantages of simplicity of immobilization, high sensitivity, high specificity, low sample requirement, high reusability, no label and no pretreatment etc.

Antibodies, Monoclonal↗
PubMed2004

Production of monoclonal and polyclonal antibodies against prostate-specific antigen, a prostate cancer serum marker.

The aim of this study was to produce monoclonal and polyclonal antibodies against prostate-specific antigen (PSA), a prostate cancer serum marker. Hyperimmune ICR mice produced polyclonal antibodies (PoAbs) after injection with 0.5 mL of pristane, and were injected with NS-1 myeloma cells 2 weeks later. Hyperimmune Balb/c mice were used for the production of monoclonal antibodies (MAbs). Mice were immunized four times and given a final boost, and their spleen cells were collected and fused with NS-1 myeloma cells under the presence of PEG 1500. The fused cells were then selected in the HAT-RPMIX medium. Anti-PSA antibody-secreting hybridoma cell lines with high titer were cloned by enzyme-linked immunosorbent assay (ELISA) and then subcloned by limiting dilution in 15% fetal bovine serum (FBS) HT-RPMIX medium. Twelve murine hybridoma producing anti-PSA MAbs were obtained and designated C3m1G11, B3m1E5, C3m1E8, C3m1C5, C3m2F4, C3m1F8, C3m2B3, C3m2E6, B3m2B11, B3m2F2, C3m2C7, and C3m2D9. Isotypes of these MAbs were identified as IgG2a heavy chain and kappa light chain. Hitrap Protein A column was used for the purification of polyclonal and monoclonal antibodies. The purity analysis of MAb was performed by capillary electrophoresis.

Antibodies↗
PubMed2004

Cardiac troponin I levels are a risk factor for mortality and multiple organ failure in noncardiac critically ill patients and have an additive effect to the APACHE II score in outcome prediction.

Cardiac troponin I (cTnI) is a specific marker of myocardial damage used in the diagnosis of acute coronary syndrome (ACS). Recent studies have shown that cTnI levels can also be elevated in patients without ACS, such as in sepsis and trauma patients, and that this is associated with an adverse prognosis. We have evaluated the clinical implications and prognostic significance of serum cTnI levels in noncardiac critically ill patients in a prospective observational study in a general medical intensive care unit at a tertiary-level hospital. A total of 108 consecutive patients without ACS or other cardiac disease was enrolled. Serum cTnI levels were measured on admission using enzyme-linked immunoabsorbant assay kits. Clinical laboratory parameters and outcome were compared between patients with elevated and normal cTnI levels. The prognostic significance of cTnI levels and the Acute Physiology And Chronic Health Evaluation (APACHE) II score was also analyzed. Forty-nine patients (45%) had elevated cTnI levels and 59 (55%) had normal levels. Compared with patients with normal cTnI levels, patients with elevated levels had a higher incidence of new failure of two or more organs, had a lower left ventricular ejection fraction during admission, were more likely to be associated with bacteremia, and had a higher intensive care unit mortality; they also had a significantly shorter survival over a 180-day follow up, before and after stratification by the APACHE II score. Multiple organ failure was the leading cause of mortality in patients with elevated cTnI levels. By multivariate analysis, elevated cTnI levels, a high APACHE II score, and underlying cancer were the three most important independent predictors for a shorter survival. Combination analysis showed a shorter survival in patients with a high APACHE II score plus elevated cTnI levels than in patients with a high APACHE II score or elevated cTnI levels alone. In conclusion, elevated serum cTnI levels is a risk factor for multiple organ failure and mortality in noncardiac critically ill patients, and the cTnI levels and APACHE II score have an additive effect in outcome prediction.

Aged↗
PubMed2004

Trends and antimicrobial resistance of pathogens causing bloodstream infections among febrile neutropenic adults with hematological malignancy.

BACKGROUND AND PURPOSE: The microbiological spectrum in cancer patients with febrile neutropenia has changed over the past several decades in western countries. The growing incidence of antimicrobial resistance is an inevitable consequence of the widespread use of antibiotics in medical settings. The aim of this study was to clarify the trends and antimicrobial resistance among pathogens causing bloodstream infections in febrile neutropenic adults with hematological malignancies. METHODS: The characteristics of pathogens causing bloodstream infection isolated from patients with febrile neutropenia who were treated at National Taiwan University Hospital from 1996 to 2001 were reviewed. A total of 1174 pathogens were isolated from 3093 admissions to a hematological ward during this period. Among them, 738 isolates were recovered from patients with febrile neutropenia. RESULTS: The majority (93%) of these neutropenic febrile patients had underlying acute leukemia or lymphoma. Gram-negative bacteria accounted for 57% of isolated pathogens, followed by Gram-positive bacteria (32%), fungi (7%), and anaerobes (3%). In decreasing frequency, Escherichia coli (13%), Klebsiella pneumoniae (12%), Enterobacter cloacae (7%), Pseudomonas aeruginosa (6%), and Acinetobacter baumannii (5%) were the predominant Gram-negative bacteria, while coagulase-negative staphylococci (13%), viridans group streptococci (4%), and Staphylococcus aureus (4%) were the major Gram-positive pathogens. Two-thirds (20/30) of S. aureus isolates were resistant to oxacillin. No vancomycin-resistant enterococci were isolated. Resistance to cefotaxime was found in 63% of E. cloacae, 13% of K. pneumoniae and 10% of E. coli. Overall, 33% of E. coli and 13% of K. pneumoniae were resistant to ciprofloxacin. CONCLUSIONS: This study indicates that the microbiological spectrum of microorganisms causing bloodstream infections in neutropenic febrile patients with hematological malignancies at National Taiwan University Hospital is different from western countries in that Gram-negative bacteria remain the predominant pathogens. Antimicrobial resistance among these pathogens is high and E. coli and K. pneumoniae isolates with resistance to third-generation cephalosporins and ciprofloxacin are increasing.

Adult↗
PubMed2003

SOCS1 methylation in patients with newly diagnosed acute myeloid leukemia.

The proliferation and differentiation of hematopoietic precursor cells depend on various cytokines. The suppressor of cytokine signaling-1 (SOCS1) down-regulates Janus kinases/signal transducers and activators of transcription (JAK/STAT) pathway activity and inhibits the biological effects of cytokines. SOCS1 has been shown to have tumor-suppressor activity, and methylation of this gene, resulting in transcriptional silencing, has been found in 65% of hepatocellular carcinoma and has been suggested to play an important role in the development of the cancer. The methylation status of the SOCS1 gene in acute myeloid leukemia (AML) has not been reported before. In this study, we analyzed SOCS1 methylation in 89 patients with newly diagnosed AML and correlated the result with immunophenotypes, cytogenetics, clinical features, and treatment outcome. SOCS1 methylation was found in the leukemic cells from 53 patients (60%). Thirteen (76%) of the 17 patients with t(15;17) had SOCS1 methylation, whereas this gene was methylated in only one (11%) of the nine patients with t(8;21). The frequencies of SOCS1 methylation among various cytogenetic subgroups differed significantly (P = 0.014). Other clinical and laboratory parameters and the disease-free survival and overall survival were similar between patients with and without SOCS1 methylation. In conclusion, SOCS1 methylation occurs in more than half of AML cases, correlates with cytogenetic abnormalities, and may play an important role in the development of subsets of AML.

Bone Marrow Cells↗
PubMed2002

Production of monoclonal and polyclonal antibodies against human alphafetoprotein, a hepatocellular tumor marker.

The objective of this study is to produce and purify monoclonal antibodies and polyclonal antibodies (PAbs) against human alphafetoprotein (AFP). Hyperimmune ICR mice produced PAbs after injection with 0.5 mL pristane, and were injected with NS-1 myeloma cells 2 weeks later. Hyperimmune Balb/c mice were used for the production of MAbs. Mice were immunized four times, given a final boost, and their spleen cells were collected and fused with NS-1 myeloma cells under the presence of PEG 1500. The fused cells were then selected in the hypoxanthine, aminopterine, and thymidine (HAT)-RPMIX medium. Anti-AFP antibody-secreting hybridoma cell lines with high titer were cloned by enzyme-linked immunosorbent assay (ELISA) and then subcloned by limiting dilution in 15% fetal bovine serum (FBS), hypoxanthine, thymidine (HT)-RPMIX medium. Twelve murine hybridoma producing anti-AFP MAbs were obtained and designated as A73F3, A73E8, B73C5, A73G3, A73F8, 67B3, B73C2, B73E1, A73G2, B73G7, B73D7, and B73F4. Isotypes of these MAbs were identified as IgG(1) heavy chain and kappa light chain. The MAbs with high purity were obtained by affinity chromatography. The purity analysis of AFP and the MAbs was performed by capillary electrophoresis.

Animals↗
PubMed2002

Determination of alpha-fetoprotein in human serum by a quartz crystal microbalance-based immunosensor.

BACKGROUND: Increased alpha-fetoprotein (AFP) in adult plasma is considered an early indication of hepatocellular carcinoma and teratoblastoma. The aim of this study was to develop a rapid method to measure AFP in human serum by use of a direct immunosensor based on a quartz crystal microbalance (QCM). METHODS: A self-assembled monolayer prepared by the cystamine method was applied to immobilize anti-AFP monoclonal antibodies on the gold surface of a quartz crystal. The frequency shifts of the QCM were measured and related to AFP concentrations. The piazoimmunosensor used no labeled reagent and no pretreatment of samples. RESULTS: Ten cycles of measurements could be performed on the gold surface of the same crystal regenerated with a solution of glycine-HCl. A linear relationship existed between the frequency shifts (Hz) and the log values of AFP concentrations from 0.1 to 100 microg/L in buffer and human serum. When used for 15 days, the frequency shifts were all >95% of those on the response at the first day. The regression equation was y = 1.03x - 0.06 (S(y/x) = 3.92; r = 0.9987) for this QCM method and RIA in 29 clinical human serum samples. CONCLUSIONS: The QCM sensor can measure AFP in buffer and human serum and offers advantages of high specificity, reusability, low detection limit, no label or sample pretreatment, and low sample requirement. The assay format of the immunosensor was more rapid and simpler than conventional methods.

Antibodies, Monoclonal↗