42 results on '"Chen, Yu-Ching"'
Search Results
2. Pay-for-performance and continuity of care synergistically reduced amputation of lower extremity in patients with diabetes: a population-based cohort study.
- Author
-
Chen, Yu-Ching, Liao, Yi-Han, Ku, Li-Jung Elizabeth, and Wang, Jung-Der
- Abstract
Background: Diabetic foot is a common and costly complication of diabetes. No existing study has looked at the effect of continuity of care on amputations of diabetes (DM) patients while considering pay-for-performance (P4P) participation. We investigated the impact of the P4P program and the continuity of care index (COCI) on the incidence of lower extremity amputations (LEA) among diabetics in Taiwan. Methods: This was a population-based cohort study using insurance claims data from 1997 to 2013. We selected 15,650 DM patients in the P4P program along with age- and sex-matched non-P4P participants at a 1:4 ratio. Time-weighted average (TWA) of the COCI was calculated and included in the time-dependent Cox proportional hazard models to examine the impact of P4P and COCI on the risk of LEA, while controlling for individual and area level characteristics. Results: During four-year follow-up, 1816 subjects experienced LEA. The cumulative LEA hazard rate of the P4P group (n = 153) was significantly lower than that of the non-P4P group (n = 1663) (hazard ratio = 0.37, 95% CI = 0.31–0.43, p < 0.0001, by log-rank test). In the time-dependent Cox proportional hazard model, the adjusted hazard ratios (aHR) for the P4P group was 0.35, (p < 0.0001). With the low COCI (< 0.50) group as the reference, the aHR of LEA was 0.49 (p < 0.0001) for the middle COCI group, (p < 0.0001), and the aHR of LEA for the high COCI (≥ 0.80) group was 0.23 (p < 0.0001). Conclusions: Participating in the P4P program and increasing COCI might reduce the risk of amputation for DM patients, independently and synergistically. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
3. Pay-for-performance and continuity of care synergistically reduced amputation of lower extremity in patients with diabetes: a population-based cohort study.
- Author
-
Chen, Yu-Ching, Liao, Yi-Han, Ku, Li-Jung Elizabeth, and Wang, Jung-Der
- Abstract
Background: Diabetic foot is a common and costly complication of diabetes. No existing study has looked at the effect of continuity of care on amputations of diabetes (DM) patients while considering pay-for-performance (P4P) participation. We investigated the impact of the P4P program and the continuity of care index (COCI) on the incidence of lower extremity amputations (LEA) among diabetics in Taiwan. Methods: This was a population-based cohort study using insurance claims data from 1997 to 2013. We selected 15,650 DM patients in the P4P program along with age- and sex-matched non-P4P participants at a 1:4 ratio. Time-weighted average (TWA) of the COCI was calculated and included in the time-dependent Cox proportional hazard models to examine the impact of P4P and COCI on the risk of LEA, while controlling for individual and area level characteristics. Results: During four-year follow-up, 1816 subjects experienced LEA. The cumulative LEA hazard rate of the P4P group (n = 153) was significantly lower than that of the non-P4P group (n = 1663) (hazard ratio = 0.37, 95% CI = 0.31–0.43, p < 0.0001, by log-rank test). In the time-dependent Cox proportional hazard model, the adjusted hazard ratios (aHR) for the P4P group was 0.35, (p < 0.0001). With the low COCI (< 0.50) group as the reference, the aHR of LEA was 0.49 (p < 0.0001) for the middle COCI group, (p < 0.0001), and the aHR of LEA for the high COCI (≥ 0.80) group was 0.23 (p < 0.0001). Conclusions: Participating in the P4P program and increasing COCI might reduce the risk of amputation for DM patients, independently and synergistically. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
4. Pay-for-performance and continuity of care synergistically reduced amputation of lower extremity in patients with diabetes: a population-based cohort study.
- Author
-
Chen, Yu-Ching, Liao, Yi-Han, Ku, Li-Jung Elizabeth, and Wang, Jung-Der
- Abstract
Background: Diabetic foot is a common and costly complication of diabetes. No existing study has looked at the effect of continuity of care on amputations of diabetes (DM) patients while considering pay-for-performance (P4P) participation. We investigated the impact of the P4P program and the continuity of care index (COCI) on the incidence of lower extremity amputations (LEA) among diabetics in Taiwan. Methods: This was a population-based cohort study using insurance claims data from 1997 to 2013. We selected 15,650 DM patients in the P4P program along with age- and sex-matched non-P4P participants at a 1:4 ratio. Time-weighted average (TWA) of the COCI was calculated and included in the time-dependent Cox proportional hazard models to examine the impact of P4P and COCI on the risk of LEA, while controlling for individual and area level characteristics. Results: During four-year follow-up, 1816 subjects experienced LEA. The cumulative LEA hazard rate of the P4P group (n = 153) was significantly lower than that of the non-P4P group (n = 1663) (hazard ratio = 0.37, 95% CI = 0.31–0.43, p < 0.0001, by log-rank test). In the time-dependent Cox proportional hazard model, the adjusted hazard ratios (aHR) for the P4P group was 0.35, (p < 0.0001). With the low COCI (< 0.50) group as the reference, the aHR of LEA was 0.49 (p < 0.0001) for the middle COCI group, (p < 0.0001), and the aHR of LEA for the high COCI (≥ 0.80) group was 0.23 (p < 0.0001). Conclusions: Participating in the P4P program and increasing COCI might reduce the risk of amputation for DM patients, independently and synergistically. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
5. Pay-for-performance and continuity of care synergistically reduced amputation of lower extremity in patients with diabetes: a population-based cohort study.
- Author
-
Chen, Yu-Ching, Liao, Yi-Han, Ku, Li-Jung Elizabeth, and Wang, Jung-Der
- Subjects
- *
LEG amputation , *CONTINUUM of care , *PROPORTIONAL hazards models , *PEOPLE with diabetes , *FOOT diseases , *TRAUMATIC amputation , *COHORT analysis - Abstract
Background: Diabetic foot is a common and costly complication of diabetes. No existing study has looked at the effect of continuity of care on amputations of diabetes (DM) patients while considering pay-for-performance (P4P) participation. We investigated the impact of the P4P program and the continuity of care index (COCI) on the incidence of lower extremity amputations (LEA) among diabetics in Taiwan.Methods: This was a population-based cohort study using insurance claims data from 1997 to 2013. We selected 15,650 DM patients in the P4P program along with age- and sex-matched non-P4P participants at a 1:4 ratio. Time-weighted average (TWA) of the COCI was calculated and included in the time-dependent Cox proportional hazard models to examine the impact of P4P and COCI on the risk of LEA, while controlling for individual and area level characteristics.Results: During four-year follow-up, 1816 subjects experienced LEA. The cumulative LEA hazard rate of the P4P group (n = 153) was significantly lower than that of the non-P4P group (n = 1663) (hazard ratio = 0.37, 95% CI = 0.31-0.43, p < 0.0001, by log-rank test). In the time-dependent Cox proportional hazard model, the adjusted hazard ratios (aHR) for the P4P group was 0.35, (p < 0.0001). With the low COCI (< 0.360) group as the reference, the aHR of LEA was 0.49 (p < 0.0001) for the middle COCI group, (p < 0.0001), and the aHR of LEA for the high COCI (≥0.643) group was 0.23 (p < 0.0001).Conclusions: Participating in the P4P program and increasing COCI might reduce the risk of amputation for DM patients, independently and synergistically. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
6. Prognostic factors and population-based analysis of melanoma with sentinel lymph node biopsy.
- Author
-
Wu, Ping-Chung, Chen, Yu-Ching, Chen, Hsiu-Min, and Chen, Lee-Wei
- Subjects
- *
SENTINEL lymph node biopsy , *SURVIVAL rate , *MELANOMA , *FACTOR analysis , *PROGNOSIS , *PERCENTILES , *SOCIAL status - Abstract
Cutaneous malignant melanoma is a rare but fatal disease in East Asia. Despite its increasing incidence, a general lack of awareness about the disease was noted. This study aims to provide population-based prognostic analysis of melanoma with sentinel lymph node biopsy (SLNB) in Taiwan. We conducted this retrospective cohort study using the data from Taiwan National Health Insurance Research Database during 1997–2013. The study cohort contains 3284 patients. The 5-year survival rates of patients undergoing SLNB and not undergoing SLNB were 45.5% and 33.6%. In multivariate analysis, age ≥ 80 years [adjusted hazard ratio (aHR) = 2.15] and male (aHR = 1.19) were associated with a poorer prognosis, while high social economic status (SES) (aHR = 0.69) and undergoing SLNB (aHR = 0.84) were good prognostic factors. Old age and low SES were associated with lower percentages of patients undergoing SLNB (P < 0.001). E-value analysis suggested robustness to unmeasured confounding. In conclusion, undergoing SLNB was associated with a better prognosis. The poor prognosis of old age and low SES may be due to decreased percentages of patients undergoing SLNB. Therefore, we recommend that SLNB should be performed on patients, especially in old age or low SES, who are candidates for SLNB according to current guidelines to achieve maximal survival. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
7. Tumor location on MRI determines outcomes of patients with prostate cancer after total prostate cryoablation.
- Author
-
Chen, Chung-Hsin, Chen, Yu-Ching, and Pu, Yeong-Shiau
- Subjects
- *
MAGNETIC resonance imaging , *PROSTATE cancer patients , *SEMINAL vesicles , *CRYOSURGERY , *PROSTATE , *PROSTATE tumors - Abstract
We investigated the association between tumor location on multiparametric magnetic resonance imaging (mpMRI) and outcomes of prostate cancer patients after primary total prostate cryoablation (PTPC). Between March 2010 and December 2012, consecutive 192 prostate cancer patients receiving PTPC were enrolled. Tumor locations were determined and classified as anterior apex (AA), anterior midgland (AM), anterior base (AB), posterior apex (PA), posterior midgland (PM) and posterior base (PB) using mpMRI. Midline location, central location, seminal vesicle invasion, extraprostatic extension, multiple tumors, and tumor volume were also identified. Prostate local recurrence and biochemical failure were considered as primary and secondary endpoints, respectively. Tumors on mpMRI were identified in 148 (77.1%) patients. Tumor locations were most frequently noted in PM (89, 46.4%), followed by AM (55, 28.6%), PB (53, 27.6%), PA (46, 24%), AA (35, 18.2%) and AB (31, 16.1%). Midline and central tumors were observed in 34 (17.7%) and 14 (7.3%) patients, respectively. During a median follow-up duration of 81 months (range, 2–114 months), 71 (37.0%) and 29 (40.8%) patients experienced biochemical failure and local recurrence, respectively. Multivariable analyses revealed only AA tumors increased the risk of local recurrences (HR = 2.98, 95% CI. 1.36–6.49). None of location-related parameters was associated with biochemical failure. Tumor location on mpMRI has a significant association with local tumor recurrence in patients receiving PTPC. Physicians should be cautious when conducting cryoablation for prostate tumors in AA location. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
8. Candidate periodically variable quasars from the Dark Energy Survey and the Sloan Digital Sky Survey.
- Author
-
Chen, Yu-Ching, Liu, Xin, Liao, Wei-Ting, Holgado, A Miguel, Guo, Hengxiao, Gruendl, Robert A, Morganson, Eric, Shen, Yue, Zhang, Kaiwen, Abbott, Tim M C, Aguena, Michel, Allam, Sahar, Avila, Santiago, Bertin, Emmanuel, Bhargava, Sunayana, Brooks, David, Burke, David L, Carnero Rosell, Aurelio, Carollo, Daniela, and Carrasco Kind, Matias
- Subjects
- *
DARK energy , *ASTRONOMICAL surveys , *BINARY black holes , *SUPERMASSIVE black holes , *QUASARS , *LIGHT curves - Abstract
Periodically variable quasars have been suggested as close binary supermassive black holes. We present a systematic search for periodic light curves in 625 spectroscopically confirmed quasars with a median redshift of 1.8 in a 4.6 deg2 overlapping region of the Dark Energy Survey Supernova (DES-SN) fields and the Sloan Digital Sky Survey Stripe 82 (SDSS-S82). Our sample has a unique 20-yr long multicolour (griz) light curve enabled by combining DES-SN Y6 observations with archival SDSS-S82 data. The deep imaging allows us to search for periodic light curves in less luminous quasars (down to r ∼23.5 mag) powered by less massive black holes (with masses ≳ 108.5 M ⊙) at high redshift for the first time. We find five candidates with significant (at >99.74 per cent single-frequency significance in at least two bands with a global p-value of ∼7 × 10−4–3 × 10−3 accounting for the look-elsewhere effect) periodicity with observed periods of ∼3–5 yr (i.e. 1–2 yr in rest frame) having ∼4–6 cycles spanned by the observations. If all five candidates are periodically variable quasars, this translates into a detection rate of |${\sim }0.8^{+0.5}_{-0.3}$| per cent or |${\sim }1.1^{+0.7}_{-0.5}$| quasar per deg2. Our detection rate is 4–80 times larger than those found by previous searches using shallower surveys over larger areas. This discrepancy is likely caused by differences in the quasar populations probed and the survey data qualities. We discuss implications on the future direct detection of low-frequency gravitational waves. Continued photometric monitoring will further assess the robustness and characteristics of these candidate periodic quasars to determine their physical origins. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
9. Different histopathologic profiles and outcomes between sun-exposed BCC and non-sun-exposed BCC.
- Author
-
Li, Chia-Lun, Chen, Yu-Ching, Yang, Kuo-Chung, and Chen, Lee-Wei
- Subjects
- *
BASAL cell carcinoma , *DISEASE relapse , *TUMOR risk factors , *ADENOIDS - Abstract
Asian population is a low-risk group for basal cell carcinoma (BCC) and there is little data available in this setting. Sun-exposed BCC (SEBCC) may possess a different pathogenic mechanism from non-sun-exposed BCC (NSEBCC). To compare the histopathological profiles and outcomes between SEBCC and NSEBCC, and to assess the risk factors for tumor recurrences. Retrospective cohort study on 372 patients with pathologically diagnosed BCC from January 1, 1990 to August 31, 2017. Data were derived from a single medical center in Taiwan. SEBCC presented with higher Clark level and more high-risk factors for recurrence than NSEBCC. Nodular, micronodular, infiltrating/mixed infiltrating, basosquamous, and adenoid types were predominant in SEBCC, as superficial type in NSEBCC. Risk factors for recurrence included infiltrating/mixed-infiltrating subtypes and synchronous basosquamous cell carcinoma. No recurrence events were observed in NSEBCC. Our study showed an acceptable recurrence rate (4.2%) of the whole population after excision even under a smaller surgical margin width than suggested by current guidelines. SEBCC had a higher recurrence rate with a significantly different tumor characteristic from NSEBCC and a greater tumor depth than NSEBCC. A wider surgical margin in SEBCC than NSEBCC is suggested. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
10. Enhancement of piezophototronic hydrogen evolution reaction through the polarization of ferroelectric Bi4Ti3O12 microplates.
- Author
-
Chang, Shun Cheng, Chen, Po-Han, Chen, Yu-Ching, and Wu, Jyh Ming
- Subjects
- *
HYDROGEN evolution reactions , *MICROPLATES , *CHARGE carrier lifetime , *LEAD titanate , *PIEZORESPONSE force microscopy , *INTERSTITIAL hydrogen generation - Abstract
In this study, we analyzed the properties of Bi 4 Ti 3 O 12 microplates in the context of hydrogen evolution reaction. Piezoresponse force microscopy revealed a typical butterfly curve, indicating that as-synthesized Bi 4 Ti 3 O 12 exhibits ferroelectric properties. Under ultrasonication, the amount of hydrogen produced by polarized (2000 V) Bi 4 Ti 3 O 12 increased from 728 to 1349 μmol g−1, which was 1.85 times higher than that generated by unpolarized Bi 4 Ti 3 O 12. The increase in hydrogen evolution rate may be attributed to the gradual alignment of polarization within the ferroelectric domains of Bi 4 Ti 3 O 12. Moreover, with synergistic piezophototronic activity, the amount of hydrogen produced by Bi 4 Ti 3 O 12 was further increased to 1478 μmol g−1, which was 200% higher than that generated by unpolarized Bi 4 Ti 3 O 12. Theoretical calculations revealed that Bi 4 Ti 3 O 12 microplates exhibit a high piezoelectric potential along the x - axis, which is consistent with the spontaneous polarization of the microplates. By applying an external polarization field, ferroelectric polarization was activated to effectively separate free charges and extend carrier lifetime (from 0.6 to 0.84 ns). The application of an external electric field to ferroelectric Bi 4 Ti 3 O 12 appears to be a favorable strategy for enhancing its piezophototronic activity. Our findings may facilitate future studies in the fields of environmental science and renewable energy. The theoretical calculation demonstrated that Bi 4 Ti 3 O 12 microplates exhibit a high piezoelectric potential along the x - axis, which is consistent with the spontaneous polarization of Bi 4 Ti 3 O 12 microplates. By applying an external field of poling treatment, ferroelectric polarization could be activated to separate free charges and prolong carrier lifetime effectively from 0.6 to 0.84 ns, producing H 2 gas of 1478 μ m o l · g − 1 through piezophotronic process. [Display omitted] • Enhanced Piezophototronic catalytic Hydrogen Evolution Reaction by the applied electric field to Bi 4 Ti 3 O 12 microplates. • With synergistic piezophototronic activities, hydrogen generation enhanced to 1478 μ m o l · g − 1 , 200% higher than that of unpoled Bi 4 Ti 3 O 12. • Applying an external poling treatment field and prolonging carrier lifetime effectively from 0.6 to 0.84 ns. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
11. Piezo‐Flexocatalysis of Single‐Atom Pt‐Loaded Graphitic Carbon Nitride.
- Author
-
Wang, Yu Teng, Lin, Hsun‐Yen, Chen, Yu‐Ching, Lin, Yan‐Gu, and Wu, Jyh Ming
- Abstract
This study develops a single‐atom Pt‐loaded graphitic carbon nitride (SA‐Pt/CN) and evaluates its piezo‐flexocatalytic properties by conducting a hydrogen evolution reaction (HER) and Rhodamine B (RB) dye degradation test under ultrasonic vibration in the dark. SA‐Pt/CN has a hydrogen gas yield of 1283.8 µmol g−1 h−1, which is 23.3 times higher than that of pristine g‐C3N4. Moreover, SA‐Pt/CN enhances the dye degradation reaction rate by ≈2.3 times compared with the pristine sample. SA‐Pt/CN exhibits lattice distortion and strain gradient enlargement caused by the single atom Pt at the N sites of g‐C3N4, which disrupts the symmetric structure and contributes to the enhancement of piezoelectric and flexoelectric polarization. As far as it is known, this is the first study to investigate the piezo‐flexocatalytic reaction of SA‐Pt/CN without light irradiation and provides new insights into single‐atom piezocatalysts. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
12. Correction: Pay-for-performance and continuity of care synergistically reduced amputation of lower extremity in patients with diabetes: a population-based cohort study.
- Author
-
Chen, Yu-Ching, Liao, Yi-Han, Ku, Li-Jung Elizabeth, and Wang, Jung-Der
- Abstract
Pay-for-performance and continuity of care synergistically reduced amputation of lower extremity in patients with diabetes: a population-based cohort study. B Correction: BMC Health Serv Res 22, 748 (2022) b B https://doi.org/10.1186/s12913-022-08075-2 b Following publication of the original article [[1]], some numbers under the heading B P4P & COCI in Table 2 b needs to be moved from the column B Model A b SP B a b sp to the column B Model B b SP B b b sp . [Extracted from the article]
- Published
- 2022
- Full Text
- View/download PDF
13. Iterative synthesis of monodisperse pendants for making comb-like polyurethanes.
- Author
-
Wu, Chien-Hsin, Chen, Yu-Ching, Dai, Shenghong A., Chen, Su-Chen, Tung, Shih-Huang, Lee, Rong-Ho, Su, Wen-Chiung, and Jeng, Ru-Jong
- Subjects
- *
POLYURETHANES , *MALONAMIDES , *HYDROGEN bonding , *PHASE transitions , *CHEMICAL synthesis - Abstract
Polyurethanes grafted with well-defined polar pendants were synthesized and investigated. A series of linear and dendritic poly(urea/malonamide)s with uniform chain length were first prepared from an iterative synthesis route, which is based on a dual-functional building block, 4-isocyanate-4´-(3,3-dimethyl-2,4-dioxo-azetidine)diphenyl methane (IDD). Moreover, side chain polyurethanes (SPUs) bearing azetidine-2,4-dione functional groups were prepared from one pot reaction for following post-functionalization of poly(urea/malonamide)s when IDD-diols were added to polyurethane prepolymers as chain extenders. Subsequently, the azetidine-2,4-dione functional groups on the SPUs underwent addition reactions with amino functional group containing dendritic or linear poly(urea/malonamide)s under mild condition, without the need of catalyst and protection/deprotection procedure to achieve polyurethanes grafted with well-defined pendants. Mechanical properties of these comb-like polyurethanes strongly depend on the architecture and the molecular length of poly(urea/malonamide) pendants, which could be adjusted by the grafting fractions of the dendritic or linear poly(urea/malonamide)s with various generations. These poly(urea/malonamide) pendants provided strong hydrogen bonding interactions to achieve physical crosslinking effects in the polyurethanes. Consequently, the polyurethanes with improved mechanical properties and sustained phase transition exhibit shape memory properties. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
14. Anti-proliferative effect on a colon adenocarcinoma cell line exerted by a membrane disrupting antimicrobial peptide KL15.
- Author
-
Chen, Yu-Ching, Tsai, Tsung-Lin, Ye, Xin-Hong, and Lin, Thy-Hou
- Published
- 2015
- Full Text
- View/download PDF
15. Colorimetric detection of Al3+ ions using triazole–ether functionalized gold nanoparticles.
- Author
-
Chen, Yu-Ching, Lee, I-Lin, Sung, Yi-Ming, and Wu, Shu-Pao
- Subjects
- *
COLORIMETRIC analysis , *ALUMINUM , *METAL ions , *TRIAZOLES , *GOLD nanoparticles , *SODIUM borohydride , *CLICK chemistry - Abstract
Abstract: A sensitive, selective colorimetric Al3+ detection method has been developed by using triazole–ether functionalized gold nanoparticles (TTP–AuNPs). Gold nanoparticles were prepared by reducing HAuCl4 with sodium borohydride in the presence of 5-(1,2-dithiolan-3-yl)-N-(prop-2-yn-1-yl)pentanamide (TP). The azide part of 2-[2-(2-azidoethoxy)ethoxy]ethanol and the acetylene part of TP were combined to form a triazole structure through a click reaction. Aggregation of TTP–AuNPs was induced immediately in the presence of Al3+ ions, yielding a color change from red to blue. This Al3+-induced aggregation of TTP–AuNPs was monitored first with the naked eye and then UV–vis spectroscopy with a detection limit of 18.0nM. The TTP–AuNPs showed excellent selectivity for Al3+, compared to other metal ions (Ag+, Ca2+, Cd2+, Co2+, Cu2+, Cr3+, Fe2+, Fe3+, Hg2+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+). In addition, TTP–AuNPs were used to detect Al3+ in sea water samples, with low interference. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
16. Triazole functionalized gold nanoparticles for colorimetric Cr3+ sensing.
- Author
-
Chen, Yu-Ching, Lee, I-Lin, Sung, Yi-Ming, and Wu, Shu-Pao
- Subjects
- *
TRIAZOLES , *GOLD nanoparticles , *COLORIMETRY , *CHROMIUM ions , *ELECTROCHEMICAL sensors , *CLICK chemistry , *CHEMICAL reactions , *CITRATES - Abstract
Abstract: Triazole functionalized gold nanoparticles (NTP@AuNPs) were synthesized through a click reaction and have been developed for sensitive and selective colorimetric Cr3+ detection. Gold nanoparticles were prepared by reducing HAuCl4 with sodium citrate and then using 4-(prop-2-ynyloxy)pyridine (PP) as the capping agent. The acetylene part of PP and the azide part of 1-(azidomethyl)-4-nitrobenzene were combined to form a triazole structure through a click reaction. Aggregation of NTP@AuNPs was induced immediately in the presence of Cr3+ ions, yielding a color change from red to purple. This Cr3+-induced aggregation of NTP@AuNPs was first monitored using the naked eye and then UV–vis spectroscopy with a detection limit of 1.4μM. In addition, NTP@AuNPs were also used to detect Cr3+ in lake water samples, with low interference. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
17. Ovatodiolide inhibits the maturation of allergen-induced bone marrow-derived dendritic cells and induction of Th2 cell differentiation.
- Author
-
Rao, Yerra Koteswara, Chen, Yu-Ching, Fang, Shih-Hua, Lai, Chih-Ho, Geethangili, Madamanchi, Lee, Chen-Chen, and Tzeng, Yew-Min
- Subjects
- *
ALLERGENS , *BONE marrow , *DENDRITIC cells , *T helper cells , *CELL differentiation , *DITERPENES - Abstract
Abstract: Ovatodiolide was a unique macrocyclic diterpenoid isolated from the traditional Chinese medicinal herb Anisomeles indica. The present study attempted to examine the ovatodiolide effects on dendritic cell (DC) maturation and immuno-stimulatory activities. The effects of ovatodiolide on DC surface molecule expression, cytokine production, and capacity to induce T-cell differentiation were examined in ovalbumin (OVA)/thymic stromal lymphopoietin (TSLP)-stimulated DCs. Ovatodiolide attenuated the expression of DC surface molecules CD80, CD86, histocompatibility complex (MHC) class II, and Th2 subset of CD4+ T cells co-stimulatory molecule-OX40 ligand production. Additionally, ovatodiolide suppressed the CD4+ T cells proliferation, and production of inflammatory cytokines interleukin (IL)-4, IL-5, and tumor necrosis factor (TNF)-α. This study may be useful to develop ovatodiolide as a therapeutic adjuvant. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
18. Role of the cAMP-Dependent Carbon Catabolite Repression in Capsular Polysaccharide Biosynthesis in Klebsiella pneumoniae.
- Author
-
Lin, Ching-Ting, Chen, Yu-Ching, Jinn, Tzyy-Rong, Wu, Chien-Chen, Hong, Yi-Ming, and Wu, Wen-Hao
- Subjects
- *
CATABOLITE repression , *POLYSACCHARIDE synthesis , *KLEBSIELLA pneumoniae , *PEOPLE with diabetes , *BLOOD sugar monitoring , *GENETIC regulation , *BIOSYNTHESIS , *MICROBIAL virulence , *BACTERIA - Abstract
K. pneumoniae is the predominant pathogen isolated from liver abscesses of diabetic patients in Asian countries. Although elevated blood glucose levels cause various immune problems, its effects on K. pneumoniae virulence are unknown. This study investigated the regulation of capsular polysaccharide (CPS) biosynthesis, a major determinant for K. pneumoniae virulence, in response to exogenous glucose. We found that K. pneumoniae produce more CPS in glucose-rich medium via reduction in cyclic AMP (cAMP) levels. Individual deletion of cyaA or crp, which respectively encode adenylate cyclase and cAMP receptor protein in K. pneumoniae, markedly increased CPS production, while deletion of cpdA, which encodes cAMP phosphodiesterase, decreased CPS production. These results indicate that K. pneumoniae CPS biosynthesis is controlled by the cAMP-dependent carbon catabolite repression (CCR). To investigate the underlying mechanism, quantitative real-time PCR and promoter-reporter assays were used to verify that the transcription of CPS biosynthesis genes, which are organized into 3 transcription units (orf1-2, orf3-15, and orf16-17), were activated by the deletion of crp. Sequence analysis revealed putative CRP binding sites located on Porf3-15 and Porf16-17, suggesting direct CRP-cAMP regulation on the promoters. These results were then confirmed by electrophoretic mobility shift assay. In addition, we found putative CRP binding sites located in the promoter region of rcsA, which encodes a cps transcriptional activator, demonstrating a direct repression of CRP-cAMP and PrcsA. The deletion of rcsA in mutation of crp partially reduced CPS biosynthesis and the transcription of orf1-2 but not of orf3-15 or orf16-17. These results suggest that RcsA participates in the CRP-cAMP regulation of orf1-2 transcription and influences CPS biosynthesis. Finally, the effect of glucose and CCR proteins on CPS biosynthesis also reflects bacterial resistance to serum killing. We here provide evidence that K. pneumoniae increases CPS biosynthesis for successful infection in response to exogenous glucose via cAMP-dependent CCR. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
19. On the AGN nature of broad balmer emission in four low-redshift metal-poor galaxies.
- Author
-
Burke, Colin J, Liu, Xin, Chen, Yu-Ching, Shen, Yue, and Guo, Hengxiao
- Subjects
- *
EMISSION-line galaxies , *GALAXIES , *GALACTIC redshift , *ACTIVE galaxies , *ACTIVE galactic nuclei , *REDSHIFT - Abstract
We report on continued, ∼15-yr long, broad Balmer emission lines in three metal-poor dwarf emission-line galaxies selected from Sloan Digital Sky Survey spectroscopy. The persistent luminosity of the broad Balmer emission indicates the galaxies are active galactic nuclei (AGNs) with virial black hole masses of ∼106.7–107.0 M⊙. The lack of observed hard X-ray emission and the possibility that the Balmer emission could be due to a long-lived stellar transient motivated additional follow-up spectroscopy. We also identify a previously unreported blueshifted narrow absorption line in the broad H α feature in one of the AGNs, indicating an AGN-driven outflow with hydrogen column densities of order 1017 cm−2. We also extract light curves from the Catalina Real-Time Transient Survey and the Zwicky Transient Facility. We detect probable AGN-like variability in three galaxies, further supporting the AGN scenario. This also suggests the AGNs are not strongly obscured. This sample of galaxies are among the most metal-poor that host an AGN (Z = 0.05–0.16 Z⊙). We speculate they may be analogues to seed black holes which formed in unevolved galaxies at high redshift. Given the rarity of metal-poor AGNs and small sample size available, we investigate prospects for their identification in future spectroscopic and photometric surveys. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
20. Sorafenib with Transarterial Chemoembolization Achieves Improved Survival vs. Sorafenib Alone in Advanced Hepatocellular Carcinoma: A Nationwide Population-Based Cohort Study.
- Author
-
Kok, Victor C., Chen, Yu-Ching, Chen, Yang-Yuan, Su, Yu-Chieh, Ku, Ming-Chang, Kuo, Jung-Tsung, and Yoshida, Go J.
- Subjects
- *
SORAFENIB , *COMBINED modality therapy , *CONFIDENCE intervals , *HEPATOCELLULAR carcinoma , *LONGITUDINAL method , *METASTASIS , *OPERATIVE surgery , *SURVIVAL analysis (Biometry) , *TUMOR classification , *PROPORTIONAL hazards models , *ARTERIAL catheters , *ODDS ratio , *CHEMOEMBOLIZATION , *MIDDLE age , *THERAPEUTICS - Abstract
We hypothesized that sorafenib plus transarterial chemoembolization (TACE) would confer survival benefits over sorafenib alone for advanced hepatocellular carcinoma (aHCC). We investigated this while using the population-based All-Cancer Dataset to assemble a cohort (n = 3674; median age, 60; 83% men) of patients receiving sorafenib for aHCC (Child-Pugh A) with macro-vascular invasion or nodal/distant metastases. The patients were classified into the sorafenib-TACE group (n = 426) or the propensity score-matched sorafenib-alone group (n = 1686). All of the participants were followed up until death or the end of the study. Time-dependent Cox model and the Mantel–Byar test were used for survival analysis. During the median follow-ups of 221 and 133 days for the sorafenib-TACE and sorafenib-alone groups, 164 (39%) and 916 (54%) deaths occurred, respectively; the corresponding median overall survivals (OS) were 381 and 204 days, respectively (hazard ratio, HR: 0.74; 95% confidence interval, CI, 0.63–0.88; p = 0.021). The one-year and six-month OS were 53.5% and 80.3% in the sorafenib-TACE group and 32.4% and 54.4% in the sorafenib-alone group, respectively. The major complications were comparable between the two groups. The addition of TACE to sorafenib improves survival, with a 26% reduction in mortality. These findings provide strong real-world evidence that supports this combination strategy for eligible Child-Pugh A aHCC patients. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
21. Optical Variability of the Dwarf AGN NGC 4395 from the Transiting Exoplanet Survey Satellite.
- Author
-
Burke, Colin J., Shen, Yue, Chen, Yu-Ching, Scaringi, Simone, Faucher-Giguere, Claude-Andre, Liu, Xin, and Yang, Qian
- Subjects
- *
LIGHT curves , *ACTIVE galactic nuclei , *OPTICAL measurements , *RANDOM walks , *EXTRASOLAR planets , *DWARF stars , *SUPERMASSIVE black holes - Abstract
We present optical light curves from the Transiting Exoplanet Survey Satellite (TESS) for the archetypical dwarf active galactic nucleus (AGN) in the nearby galaxy NGC 4395 hosting a ∼105M⊙ supermassive black hole (SMBH). Significant variability is detected on timescales from weeks to hours before reaching the background noise level. The ∼month-long, 30 minute-cadence, high-precision TESS light curve can be well fit by a simple damped random walk (DRW) model, with the damping timescale τDRW constrained to be days (1σ). NGC 4395 lies almost exactly on the extrapolation of the relation measured for AGNs with BH masses that are more than three orders of magnitude larger. The optical variability periodogram can be well fit by a broken power law with the high-frequency slope (−1.88 ± 0.15) and the characteristic timescale (days) consistent with the DRW model within 1σ. This work demonstrates the power of TESS light curves in identifying low-mass accreting SMBHs with optical variability, and a potential global relation that can be used to estimate SMBH masses with optical variability measurements. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
22. Spectral variability of a sample of extreme variability quasars and implications for the Mg ii broad-line region.
- Author
-
Yang, Qian, Shen, Yue, Chen, Yu-Ching, Liu, Xin, Annis, James, Avila, Santiago, Bertin, Emmanuel, Brooks, David, Buckley-Geer, Elizabeth, Carnero Rosell, Aurelio, Carrasco Kind, Matias, Carretero, Jorge, da Costa, Luiz, Desai, Shantanu, Thomas Diehl, H, Doel, Peter, Frieman, Josh, Garcia-Bellido, Juan, Gaztanaga, Enrique, and Gerdes, David
- Subjects
- *
QUASARS , *DARK energy , *OPTICAL spectroscopy , *ASTRONOMICAL surveys , *BLACK holes , *STATISTICAL sampling - Abstract
We present new Gemini/GMOS optical spectroscopy of 16 extreme variability quasars (EVQs) that dimmed by more than 1.5 mag in the g band between the Sloan Digital Sky Survey (SDSS) and the Dark Energy Survey epochs (separated by a few years in the quasar rest frame). These EVQs are selected from quasars in the SDSS Stripe 82 region, covering a redshift range of 0.5 < z < 2.1. Nearly half of these EVQs brightened significantly (by more than 0.5 mag in the g band) in a few years after reaching their previous faintest state, and some EVQs showed rapid (non-blazar) variations of greater than 1–2 mag on time-scales of only months. To increase sample statistics, we use a supplemental sample of 33 EVQs with multi-epoch spectra from SDSS that cover the broad Mg ii λ2798 line. Leveraging on the large dynamic range in continuum variability between the multi-epoch spectra, we explore the associated variations in the broad Mg ii line, whose variability properties have not been well studied before. The broad Mg ii flux varies in the same direction as the continuum flux, albeit with a smaller amplitude, which indicates at least some portion of Mg ii is reverberating to continuum changes. However, the full width at half-maximum (FWHM) of Mg ii does not vary accordingly as continuum changes for most objects in the sample, in contrast to the case of the broad Balmer lines. Using the width of broad Mg ii to estimate the black hole mass with single epoch spectra therefore introduces a luminosity-dependent bias. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
23. Deblending and classifying astronomical sources with Mask R-CNN deep learning.
- Author
-
Burke, Colin J, Aleo, Patrick D, Chen, Yu-Ching, Liu, Xin, Peterson, John R, Sembroski, Glenn H, and Lin, Joshua Yao-Yu
- Subjects
- *
LARGE Synoptic Survey Telescope , *ARTIFICIAL neural networks , *DEEP learning , *IMAGE processing - Abstract
We apply a new deep learning technique to detect, classify, and deblend sources in multiband astronomical images. We train and evaluate the performance of an artificial neural network built on the Mask Region-based Convolutional Neural Network image processing framework, a general code for efficient object detection, classification, and instance segmentation. After evaluating the performance of our network against simulated ground truth images for star and galaxy classes, we find a precision of 92 per cent at 80 per cent recall for stars and a precision of 98 per cent at 80 per cent recall for galaxies in a typical field with ∼30 galaxies arcmin−2. We investigate the deblending capability of our code, and find that clean deblends are handled robustly during object masking, even for significantly blended sources. This technique, or extensions using similar network architectures, may be applied to current and future deep imaging surveys such as Large Synoptic Survey Telescope and Wide-Field Infrared Survey Telescope. Our code, astro r-cnn , is publicly available at https://github.com/burke86/astro_rcnn. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
24. High mobility group box 1-induced epithelial mesenchymal transition in human airway epithelial cells.
- Author
-
Chen, Yu-Ching, Statt, Sarah, Wu, Reen, Chang, Hao-Teng, Liao, Jiunn-Wang, Wang, Chien-Neng, Shyu, Woei-Cherng, and Lee, Chen-Chen
- Published
- 2016
- Full Text
- View/download PDF
25. Correction to: Optical variability of quasars with 20-year photometric light curves.
- Author
-
Stone, Zachary, Shen, Yue, Burke, Colin J, Chen, Yu-Ching, Yang, Qian, Liu, Xin, Gruendl, R A, Adamów, M, Andrade-Oliveira, F, Annis, J, Bacon, D, Bertin, E, Bocquet, S, Brooks, D, Burke, D L, Carnero Rosell, A, Carrasco Kind, M, Carretero, J, da Costa, L N, and Pereira, M E S
- Subjects
- *
LIGHT curves , *QUASARS , *SUPERMASSIVE black holes - Published
- 2023
- Full Text
- View/download PDF
26. New algal lipid extraction procedure using an amphiphilic amine solvent and ionic liquid.
- Author
-
Yang, Hui-Yun, Lu, Wen-Jang, Chen, Yu-Ching, Chen, Kuo-Ti, Teng, Jui-Chin, and Wan, Hou-Peng
- Subjects
- *
BIOMASS energy , *ENERGY consumption , *ALGAL biofuels , *EXTRACTION (Chemistry) , *IONIC liquids , *DOCOSAHEXAENOIC acid - Abstract
Lipid extraction is a key step in microalgal biofuel production. However, economical microalgal biofuel production is limited by the high energy consumption of the extraction process. Therefore, in this study, we employed N-methylcyclohexylamine (MCHA) as a switchable solvent to directly extract a wet microalgal slurry, and an ionic liquid, [C 4 -mim][PF 6 ] (1-butyl-3-methylimidazolium hexafluorophosphate), was used to recover the extracted algal oil through a simple phase separation method. CO 2 was used to trigger the separation of MCHA from [C 4 -mim][PF 6 ], and MCHA was regenerated by heating and purging with N 2 . Our extraction procedure differs from conventional solvent extraction, which requires drying algal slurries before extraction. The new extraction procedure adopted in this study can be used to extract wet algal slurries directly and recycle the solvent by using a low-energy consumption method. In addition, water-soluble MCHA was investigated for DHA(docosahexaenoic acid) wet algal slurries with 85% water content, and the extraction yield could reach 85% at low stirring speeds (200 rpm). Using [C 4 -mim][PF 6 ] to separate algal oil from the crude extraction liquid, algal lipid recovery was approximately 77%. In summary, the results showed the feasibility of utilizing MCHA and [C 4 -mim][PF 6 ] as extracting and separating agents, respectively, for algal oil exaction. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
27. Dwarf AGNs from Optical Variability for the Origins of Seeds (DAVOS): insights from the dark energy survey deep fields.
- Author
-
Burke, Colin J, Liu, Xin, Shen, Yue, Phadke, Kedar A, Yang, Qian, Hartley, Will G, Harrison, Ian, Palmese, Antonella, Guo, Hengxiao, Zhang, Kaiwen, Kron, Richard, Turner, David J, Giles, Paul A, Lidman, Christopher, Chen, Yu-Ching, Gruendl, Robert A, Choi, Ami, Amon, Alexandra, Sheldon, Erin, and Aguena, M
- Subjects
- *
DARK energy , *LIGHT curves , *SPECTRAL energy distribution , *OPTICAL spectra , *STELLAR mass , *GALACTIC nuclei , *ACTIVE galactic nuclei - Abstract
We present a sample of 706, z < 1.5 active galactic nuclei (AGNs) selected from optical photometric variability in three of the Dark Energy Survey (DES) deep fields (E2, C3, and X3) over an area of 4.64 deg2. We construct light curves using difference imaging aperture photometry for resolved sources and non-difference imaging PSF photometry for unresolved sources, respectively, and characterize the variability significance. Our DES light curves have a mean cadence of 7 d, a 6-yr baseline, and a single-epoch imaging depth of up to g ∼ 24.5. Using spectral energy distribution (SED) fitting, we find 26 out of total 706 variable galaxies are consistent with dwarf galaxies with a reliable stellar mass estimate (|$M_{\ast }\lt 10^{9.5}\, {\rm M}_\odot$| ; median photometric redshift of 0.9). We were able to constrain rapid characteristic variability time-scales (∼ weeks) using the DES light curves in 15 dwarf AGN candidates (a subset of our variable AGN candidates) at a median photometric redshift of 0.4. This rapid variability is consistent with their low black hole (BH) masses. We confirm the low-mass AGN nature of one source with a high S/N optical spectrum. We publish our catalogue, optical light curves, and supplementary data, such as X-ray properties and optical spectra, when available. We measure a variable AGN fraction versus stellar mass and compare to results from a forward model. This work demonstrates the feasibility of optical variability to identify AGNs with lower BH masses in deep fields, which may be more 'pristine' analogues of supermassive BH seeds. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
28. Surface surgery on TiNb2O7 electrode via N2/Air atmospheric pressure plasma jet for high-rate lithium-ion battery anode.
- Author
-
Wu, Che-Ya, Hsiao, Shih-Nan, Kuo, Rui-Tung, Chen, Yu-Ching, Lin, Tzu-Ying, Hori, Masaru, and Duh, Jenq-Gong
- Subjects
- *
ATMOSPHERIC pressure plasmas , *PLASMA jets , *CERAMIC materials , *LITHIUM-ion batteries , *ELECTRIC conductivity , *ANODES - Abstract
[Display omitted] • Atmospheric Pressure Plasma Jet Technology for the treatment of the electrode. • Defects engineering on the TiNb 2 O 7 ceramics anode materials for the enhancement of electrical conductivity. • Manufacturing N-doped carbon to enhance the high-rate capability. • Enhancement of the electrolyte wettability by modification of the PVdF. • Forming lithium nitride by nitro-groups modification to prevent HF attack. TiNb 2 O 7 (TNO) is regarded as a potential anode material for its high capacity compared to Li 4 Ti 5 O 12 and high safety due to its adequate Fermi level in lithium-ion batteries. This work represents a promising method of modifying the electrode, which includes polyvinylidene fluoride (PVDF), conductive carbon, and TiNb 2 O 7 , using an atmospheric pressure plasma jet (APPj) treatment. Our results reveal that atmospheric pressure plasma jet improves the electrochemical performance by N-doped decoration on conductive carbon, electrolyte wettability enhancement on polyvinylidene fluoride binder, and defects manufacturing in TiNb 2 O 7 anode materials. Good wettability of surface free energy to 44.6 mJ/m2 in the APPj-treated (APP-10) sample contributes to improved cycling performance. Both N-doped carbon and modified TiNb 2 O 7 promote the high-rate capability. The C-rate performance of APP-10 improves by over 200 % at 10C compared to the non-treated sample (APP-0). APP-10 sample also shows 81.9 % retention after 300 cycles at 1C. The formation of Li 3 N or LiN x O y after cycling due to the nitro-group in the electrode with atmospheric pressure plasma jet offers good protection and high ionic-conductivity interface. This work demonstrates a potential solution to achieve a roll-to-roll modification without any complex synthesis processes, which is a promising technology for the affordable manufacturing of lithium-ion battery. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
29. Optical variability of quasars with 20-yr photometric light curves.
- Author
-
Stone, Zachary, Shen, Yue, Burke, Colin J, Chen, Yu-Ching, Yang, Qian, Liu, Xin, Gruendl, R A, Adamów, M, Andrade-Oliveira, F, Annis, J, Bacon, D, Bertin, E, Bocquet, S, Brooks, D, Burke, D L, Carnero Rosell, A, Carrasco Kind, M, Carretero, J, da Costa, L N, and Pereira, M E S
- Subjects
- *
LIGHT curves , *QUASARS , *DARK energy , *RANDOM walks , *POWER density , *POWER spectra - Abstract
We study the optical gri photometric variability of a sample of 190 quasars within the SDSS Stripe 82 region that have long-term photometric coverage during ∼1998−2020 with SDSS, PanSTARRS-1, the Dark Energy Survey, and dedicated follow-up monitoring with Blanco 4m/DECam. With on average ∼200 nightly epochs per quasar per filter band, we improve the parameter constraints from a Damped Random Walk (DRW) model fit to the light curves over previous studies with 10–15 yr baselines and ≲ 100 epochs. We find that the average damping time-scale τDRW continues to rise with increased baseline, reaching a median value of ∼750 d (g band) in the rest frame of these quasars using the 20-yr light curves. Some quasars may have gradual, long-term trends in their light curves, suggesting that either the DRW fit requires very long baselines to converge, or that the underlying variability is more complex than a single DRW process for these quasars. Using a subset of quasars with better-constrained τDRW (less than 20 per cent of the baseline), we confirm a weak wavelength dependence of τDRW∝λ0.51 ± 0.20. We further quantify optical variability of these quasars over days to decades time-scales using structure function (SF) and power spectrum density (PSD) analyses. The SF and PSD measurements qualitatively confirm the measured (hundreds of days) damping time-scales from the DRW fits. However, the ensemble PSD is steeper than that of a DRW on time-scales less than ∼ a month for these luminous quasars, and this second break point correlates with the longer DRW damping time-scale. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
30. IscR Regulation of Capsular Polysaccharide Biosynthesis and Iron-Acquisition Systems in Klebsiella pneumoniae CG43.
- Author
-
Wu, Chien-Chen, Wang, Chien-Kuo, Chen, Yu-Ching, Lin, Tien-Huang, Jinn, Tzyy-Rong, and Lin, Ching-Ting
- Subjects
- *
POLYSACCHARIDES , *BIOSYNTHESIS , *KLEBSIELLA pneumoniae , *OXIDATIVE stress , *SIDEROPHORES , *MESSENGER RNA - Abstract
IscR, an Fe–S cluster-containing transcriptional factor, regulates genes involved in various cellular processes. In response to environmental stimuli such as oxidative stress and iron levels, IscR switches between its holo and apo forms to regulate various targets. IscR binding sequences are classified into two types: the type 1 IscR box that is specific for holo-IscR binding, and the type 2 IscR box that binds holo- and apo-IscR. Studying Klebsiella pneumoniae CG43S3, we have previously shown that iron availability regulates capsular polysaccharide (CPS) biosynthesis and iron-acquisition systems. The present study investigated whether IscR is involved in this regulation. Compared with that in CG43S3, the amount of CPS was decreased in AP001 (ΔiscR) or AP002 (iscR3CA), a CG43S3-derived strain expressing mutated IscR mimicked apo-IscR, suggesting that only holo-IscR activates CPS biosynthesis. Furthermore, a promoter-reporter assay verified that the transcription of cps genes was reduced in AP001 and AP002. Purified IscR::His6, but not IscR3CA::His6, was also found to bind the predicted type 1 IscR box specifically in the cps promoter. Furthermore, reduced siderophore production was observed in AP004 (Δfur-ΔiscR) but not in AP005 (Δfur-iscR3CA), implying that apo-IscR activates iron acquisition. Compared with those in AP004, mRNA levels of three putative iron acquisition systems (fhu, iuc, and sit) were increased in AP005, and both purified IscR::His6 and IscR3CA::His6 bound the predicted type 2 IscR box in the fhuA, iucA, and sitA promoters, whereas IscR3CA::His6 displayed a lower affinity. Finally, we analyzed the effect of external iron levels on iscR expression. The transcription of iscR was increased under iron-depleted conditions as well as in AP001 and AP002, suggesting an auto-repression exerted by apo-IscR. Our results show that in K. pneumoniae, IscR plays a dual role in the regulation of CPS biosynthesis and iron-acquisition systems in response to environmental iron availability. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
31. Investigating the Accretion Nature of Binary Supermassive Black Hole Candidate SDSS J025214.67â'002813.7.
- Author
-
Foord, Adi, Liu, Xin, GĂĽltekin, Kayhan, Whitley, Kevin, Shi, Fangzheng, and Chen, Yu-Ching
- Subjects
- *
BINARY black holes , *SPECTRAL energy distribution , *ACTIVE galactic nuclei , *HARD X-rays , *SUPERMASSIVE black holes , *LIGHT curves - Abstract
We present results of a multiwavelength analysis of SDSS J025214.67â'002813.7, a system that has been previously classified as a binary active galactic nucleus (AGN) candidate based on periodic signals detected in the optical light curves. We use available radioâ'X-ray observations of the system to investigate the true accretion nature. Analyzing new observations from XMM-Newton and NuSTAR, we characterize the X-ray emission and search for evidence of circumbinary accretion. Although the 0.5â€"10 keV spectrum shows evidence of an additional soft emission component, possibly due to extended emission from hot nuclear gas, we find the spectral shape is consistent with that of a single AGN. Compiling a full multiwavelength spectral energy distribution (SED), we also search for signs of circumbinary accretion, such as a “notch” in the continuum due to the presence of minidisks. We find that the radioâ€"optical emission agrees with the SED of a standard, radio-quiet, AGN; however, there is a large deficit in emission blueward of âĽ1400 Ă.... Although this deficit in emission can plausibly be attributed to a binary AGN system, we find that the SED of SDSS J0252â'0028 is better explained by emission from a reddened, single AGN. However, future studies of the expected hard X-ray emission associated with binary AGNs (especially in the unequal-mass regime) will allow for more rigorous analyses of the binary AGN hypothesis. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
32. Dysregulated interactions between lamin A and SUN1 induce abnormalities in the nuclear envelope and endoplasmic reticulum in progeric laminopathies.
- Author
-
Chen, Zi-Jie, Wang, Wan-Ping, Chen, Yu-Ching, Wang, Jing-Ya, Lin, Wen-Hsin, Tai, Lin-Ai, Liou, Gan-Guang, Yang, and Chi, Ya-Hui
- Subjects
- *
PROGERIA , *NUCLEAR membranes , *ENDOPLASMIC reticulum , *POINT mutation (Biology) , *PHENOTYPES , *AMINO acids - Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is a human progeroid disease caused by a point mutation on the LMNA gene. We reported previously that the accumulation of the nuclear envelope protein SUN1 contributes to HGPS nuclear aberrancies. However, the mechanism by which interactions between mutant lamin A (also known as progerin or LAA50) and SUN1 produce HGPS cellular phenotypes requires further elucidation. Using light and electron microscopy, this study demonstrated that SUN1 contributes to progerin-elicited structural changes in the nuclear envelope and the endoplasmic reticulum (ER) network. We further identified two domains through which full-length lamin A associates with SUN1, and determined that the famesylated cysteine within the CaaX motif of lamin A has a stronger affinity for SUN1 than does the lamin A region containing amino acids 607 to 656. Famesylation of progerin enhanced its interaction with SUN1 and reduced SUN1 mobility, thereby promoting the aberrant recruitment of progerin to the ER membrane during postmitotic assembly of the nuclear envelope, resulting in the accumulation of SUN1 over consecutive cellular divisions. These results indicate that the dysregulated interaction of SUN1 and progerin in the ER during nuclear envelope reformation determines the progression of HGPS. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
33. Early detection of breast cancer rectifies inequality of breast cancer outcomes.
- Author
-
Tabár, László, Chen, Tony Hsiu-Hsi, Yen, Amy Ming-Fang, Dean, Peter B, Smith, Robert A, Jonsson, Håkan, Törnberg, Sven, Chen, Sam Li-Sheng, Chiu, Sherry Yueh-Hsia, Fann, Jean Ching-Yuan, Ku, May Mei-Sheng, Wu, Wendy Yi-Ying, Hsu, Chen-Yang, Chen, Yu-Ching, Svane, Gunilla, Azavedo, Edward, Grundström, Helene, Sundén, Per, Leifland, Karin, and Frodis, Ewa
- Subjects
- *
SURVIVAL , *CONFIDENCE intervals , *EARLY detection of cancer , *MAMMOGRAMS , *REGRESSION analysis , *TREATMENT effectiveness , *COMPARATIVE studies , *KAPLAN-Meier estimator , *DESCRIPTIVE statistics , *BREAST tumors - Abstract
Objectives: To explain apparent differences among mammography screening services in Sweden using individual data on participation in screening and with breast cancer–specific survival as an outcome. Methods: We analysed breast cancer survival data from the Swedish Cancer Register on breast cancer cases from nine Swedish counties diagnosed in women eligible for screening. Data were available on 38,278 breast cancers diagnosed and 4312 breast cancer deaths. Survival to death from breast cancer was estimated using the Kaplan–Meier estimate, for all cases in each county, and separately for cases of women participating and not participating in their last invitation to screening. Formal statistical comparisons of survival were made using proportional hazards regression. Results: All counties showed a reduction in the hazard of breast cancer death with participation in screening, but the reductions for individual counties varied substantially, ranging from 51% (95% confidence interval 46–55%) to 81% (95% confidence interval 74–85%). Survival rates in nonparticipating women ranged from 53% (95% confidence interval 40–65%) to 74% (95% confidence interval 72–77%), while the corresponding survival in women participating in screening varied from 80% (95% confidence interval 77–84%) to 86% (95% confidence interval 83–88%), a considerably narrower range. Conclusions: Differences among counties in the effect of screening on breast cancer outcomes were mainly due to variation in survival in women not participating in screening. Screening conferred similarly high survival rates in all counties. This indicates that the performance of screening services was similar across counties and that detection and treatment of breast cancer in early-stage reduces inequalities in breast cancer outcome. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
34. Dark Energy Survey identification of a low-mass active galactic nucleus at redshift 0.823 from optical variability.
- Author
-
Guo, Hengxiao, Burke, Colin J, Liu, Xin, Phadke, Kedar A, Zhang, Kaiwen, Chen, Yu-Ching, Gruendl, Robert A, Lidman, Christopher, Shen, Yue, Morganson, Eric, Aguena, Michel, Allam, Sahar, Avila, Santiago, Bertin, Emmanuel, Brooks, David, Rosell, Aurelio Carnero, Carollo, Daniela, Kind, Matias Carrasco, Costanzi, Matteo, and da Costa, Luiz N
- Subjects
- *
GALACTIC redshift , *ACTIVE galactic nuclei , *DARK energy , *SPECTRAL energy distribution , *STELLAR mass , *SEYFERT galaxies - Abstract
We report the identification of a low-mass active galactic nucleus (AGN), DES J0218−0430, in a redshift z = 0.823 galaxy in the Dark Energy Survey (DES) Supernova field. We select DES J0218−0430 as an AGN candidate by characterizing its long-term optical variability alone based on DES optical broad-band light curves spanning over 6 yr. An archival optical spectrum from the fourth phase of the Sloan Digital Sky Survey shows both broad Mg ii and broad H β lines, confirming its nature as a broad-line AGN. Archival XMM–Newton X-ray observations suggest an intrinsic hard X-ray luminosity of |$L_{{\rm 2-12\, keV}}\approx 7.6\pm 0.4\times 10^{43}$| erg s−1, which exceeds those of the most X-ray luminous starburst galaxies, in support of an AGN driving the optical variability. Based on the broad H β from SDSS spectrum, we estimate a virial black hole (BH) mass of M • ≈ 106.43–106.72 M⊙ (with the error denoting the systematic uncertainty from different calibrations), consistent with the estimation from OzDES, making it the lowest mass AGN with redshift > 0.4 detected in optical. We estimate the host galaxy stellar mass to be M * ≈ 1010.5 ± 0.3 M⊙ based on modelling the multiwavelength spectral energy distribution. DES J0218−0430 extends the M •– M * relation observed in luminous AGNs at z ∼ 1 to masses lower than being probed by previous work. Our work demonstrates the feasibility of using optical variability to identify low-mass AGNs at higher redshift in deeper synoptic surveys with direct implications for the upcoming Legacy Survey of Space and Time at Vera C. Rubin Observatory. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
35. Mammography screening reduces rates of advanced and fatal breast cancers: Results in 549,091 women.
- Author
-
Duffy, Stephen W., Tabár, László, Yen, Amy Ming‐Fang, Dean, Peter B., Smith, Robert A., Jonsson, Håkan, Törnberg, Sven, Chen, Sam Li‐Sheng, Chiu, Sherry Yueh‐Hsia, Fann, Jean Ching‐Yuan, Ku, May Mei‐Sheng, Wu, Wendy Yi‐Ying, Hsu, Chen‐Yang, Chen, Yu‐Ching, Svane, Gunilla, Azavedo, Edward, Grundström, Helene, Sundén, Per, Leifland, Karin, and Frodis, Ewa
- Subjects
- *
BREAST cancer , *MAMMOGRAMS , *CANCER diagnosis , *POISSON regression , *EARLY detection of cancer , *CAUSES of death , *RESEARCH , *CONFIDENCE intervals , *PATIENT participation , *MORTALITY , *TIME , *RESEARCH methodology , *MEDICAL screening , *DISEASE incidence , *MEDICAL cooperation , *EVALUATION research , *COMPARATIVE studies , *RESEARCH funding , *BREAST tumors - Abstract
Background: It is of paramount importance to evaluate the impact of participation in organized mammography service screening independently from changes in breast cancer treatment. This can be done by measuring the incidence of fatal breast cancer, which is based on the date of diagnosis and not on the date of death.Methods: Among 549,091 women, covering approximately 30% of the Swedish screening-eligible population, the authors calculated the incidence rates of 2473 breast cancers that were fatal within 10 years after diagnosis and the incidence rates of 9737 advanced breast cancers. Data regarding each breast cancer diagnosis and the cause and date of death of each breast cancer case were gathered from national Swedish registries. Tumor characteristics were collected from regional cancer centers. Aggregated data concerning invitation and participation were provided by Sectra Medical Systems AB. Incidence rates were analyzed using Poisson regression.Results: Women who participated in mammography screening had a statistically significant 41% reduction in their risk of dying of breast cancer within 10 years (relative risk, 0.59; 95% CI, 0.51-0.68 [P < .001]) and a 25% reduction in the rate of advanced breast cancers (relative risk, 0.75; 95% CI, 0.66-0.84 [P < .001]).Conclusions: Substantial reductions in the incidence rate of breast cancers that were fatal within 10 years after diagnosis and in the advanced breast cancer rate were found in this contemporaneous comparison of women participating versus those not participating in screening. These benefits appeared to be independent of recent changes in treatment regimens. [ABSTRACT FROM AUTHOR]- Published
- 2020
- Full Text
- View/download PDF
36. The incidence of fatal breast cancer measures the increased effectiveness of therapy in women participating in mammography screening.
- Author
-
Tabár, László, Dean, Peter B., Chen, Tony Hsiu-Hsi, Yen, Amy Ming-Fang, Chen, Sam Li-Sheng, Fann, Jean Ching-Yuan, Chiu, Sherry Yueh-Hsia, Ku, May Mei-Sheng, Wu, Wendy Yi-Ying, Hsu, Chen-Yang, Chen, Yu-Ching, Beckmann, Kerri, Smith, Robert A., and Duffy, Stephen W.
- Subjects
- *
BREAST cancer , *MAMMOGRAMS , *MEDICAL needs assessment , *HIV-positive women , *BREAST cancer treatment , *WOMEN - Abstract
Background: Women and their health care providers need a reliable answer to this important question: If a woman chooses to participate in regular mammography screening, then how much will this choice improve her chances of avoiding a death from breast cancer compared with women who choose not to participate?Methods: To answer this question, we used comprehensive registries for population, screening history, breast cancer incidence, and disease-specific death data in a defined population in Dalarna County, Sweden. The annual incidence of breast cancer was calculated along with the annual incidence of breast cancers that were fatal within 10 and within 11 to 20 years of diagnosis among women aged 40 to 69 years who either did or did not participate in mammography screening during a 39-year period (1977-2015). For an additional comparison, corresponding data are presented from 19 years of the prescreening period (1958-1976). All patients received stage-specific therapy according to the latest national guidelines, irrespective of the mode of detection.Results: The benefit for women who chose to participate in an organized breast cancer screening program was a 60% lower risk of dying from breast cancer within 10 years after diagnosis (relative risk, 0.40; 95% confidence interval, 0.34-0.48) and a 47% lower risk of dying from breast cancer within 20 years after diagnosis (relative risk, 0.53; 95% confidence interval, 0.44-0.63) compared with the corresponding risks for nonparticipants.Conclusions: Although all patients with breast cancer stand to benefit from advances in breast cancer therapy, the current results demonstrate that women who have participated in mammography screening obtain a significantly greater benefit from the therapy available at the time of diagnosis than do those who have not participated. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
37. Risk of Autoimmune Disease in Adults with Chronic Insomnia Requiring Sleep-Inducing Pills: A Population-Based Longitudinal Study.
- Author
-
Kok, Victor, Horng, Jorng-Tzong, Hung, Guo-Dung, Xu, Jia-Li, Hung, Tzu-Wei, Chen, Yu-Ching, Chen, Chien-Lung, and Kok, Victor C
- Subjects
- *
AUTOIMMUNE diseases , *INSOMNIA , *HYPNOTICS , *SENSITIVITY analysis , *DISEASE incidence , *DISEASE risk factors , *AUTOIMMUNE disease diagnosis , *CHRONIC diseases , *LONGITUDINAL method , *PUBLIC health surveillance , *DIAGNOSIS - Abstract
Background: Recent studies indicate that chronic insomnia is associated with the development of certain somatic diseases. Whether it would be associated with the development of an autoimmune disease (AID) was unknown.Objective: We aimed to examine the association and quantify the magnitude of risk for AID in individuals suffering from chronic insomnia requiring sleep-inducing pills.Design: This was a population-based, nationwide longitudinal study.Participants: Using a claims data set containing 1 million randomly sampled, insured subjects derived from the National Health Insurance Research Database, we assembled a chronic insomnia group and a 1:3 propensity score-matched comparison group (CP), which were balanced in terms of sex, age, insurance premium, urbanization, alcohol use disorder, smoking-related diagnoses, and morbid obesity.Main Measures: Person-time data with incidence rate, adjusted hazard ratios (aHR) by the Cox model, AID-free survival functions compared with the log-rank test, and a sensitivity analysis on the time lag effect were presented. Incident AID within the first year of follow-up were excluded. The error rate was controlled using the Benjamini-Hochberg procedure.Key Results: With 39,550 and 129,914 person-years' follow-up for the chronic insomnia and CP groups (n = 5,736 and 17,208), respectively, we found an increased risk for subsequent AID, representing a 70 % increase in the aHR (1.7; 95 % confidence interval [CI], 1.5-1.9, p < 0.0001). A positive association between chronic insomnia and primary Sjögren's syndrome (pSS) was observed (aHR, 1.3; 95 % CI, 1.1-1.6). Sensitivity analysis disclosed that AID risk was even stronger after 5 years of follow-up (aHR, 2.0; 95 % CI, 1.7-2.4).Conclusion: Chronic insomnia requiring sleep-inducing pills may be associated with a 70 % increased risk for future AID, particularly pSS. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
38. Cadmium-BasedQuantum Dot Induced Autophagy Formationfor Cell Survival via Oxidative Stress.
- Author
-
Luo, Yueh-Hsia, Wu, Shi-Bei, Wei, Yau-Huei, Chen, Yu-Ching, Tsai, Ming-Hsien, Ho, Chia-Chi, Lin, Shu-Yi, Yang, Chung-Shi, and Lin, Pinpin
- Subjects
- *
QUANTUM dots , *CADMIUM , *AUTOPHAGY , *OXIDATIVE stress , *NANOSTRUCTURED materials , *BIOLOGICAL systems , *REACTIVE oxygen species , *CELL-mediated cytotoxicity - Abstract
Quantumdots (QDs) are one of most utilized nanomaterials in nanocrystallinesemiconductors. QDs emit near-infrared fluorescence and can be appliedas probes for detecting vasculature and imaging in biological systems.Since QDs have potential in clinical application, the toxicity ofQDs needs to be carefully evaluated. In our present study, we elucidatethe cytotoxic mechanisms of QDs using a mouse renal adenocarcinoma(RAG) cell line. QDs in RAG cells increased intracellular reactiveoxygen species (ROS) levels and induced autophagy at 6 h, leadingto subsequent apoptosis at 24 h. QDs entered the cells and were locatedwithin the endoplasmic reticulum (ER), endosome, and lysosome at 6h and endosome, lysosome, and mitochondria at 24 h. However, QDs onlyaffected mitochondrial function and did not induce ER stress. N-Acetylcysteine, an antioxidant agent, reduced intracellularROS levels and decreased QD-induced autophagy but enhanced QD-inducedcell death. Moreover, 3-methylamphetamine (an autophagy inhibitor)also reduced the cell viability in QD-treated cells. These findingssuggest that ROS plays an essential role in the regulation of QD-inducedautophagy, which subsequently enhances cell survival. Taken together,these results suggest that oxidative stress-induced autophagy is adefense/survival mechanism against the cytotoxicity of QD. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
39. Effective aircraft maintenance schedule adjustment following incidents.
- Author
-
Yan, Shangyao, Hsiao, Fei-Yen, Guo, Jyunjhih, and Chen, Yu-Ching
- Subjects
- *
AIRLINE industry , *AIRPLANES , *MAINTENANCE , *INTEGER programming , *DECISION making , *COST control , *MATHEMATICAL programming - Abstract
In the real world, planned aircraft maintenance schedules are often affected by incidents. Airlines may thus need to adjust their aircraft maintenance schedules following the incidents that occur during routine operations. In tradition, such aircraft maintenance schedule adjustment has been performed manually, a process which is neither effective nor efficient, especially when the problem scale is large. In this study, an aircraft maintenance schedule adjustment model is developed, with the objective of minimizing the total system cost, subject to the related operating constraints. The model is formulated as a zero-one integer program and is solved using a mathematical programing solver. The effectiveness of the model is evaluated by application to a case study using data from an aircraft maintenance center in Taiwan. The test results show the proposed model, as well as the scheduling rules abstracted from the results are useful for the decision maker to adjust good maintenance schedules. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
40. Purification, crystallization and preliminary X-ray analysis of a thermostable direct haemolysin from Grimontia hollisae.
- Author
-
Wang, Yu-Kuo, Huang, Sheng-Cih, Wu, Yi-Fang, Chen, Yu-Ching, Chen, Wen-Hung, Lin, Yan-Ling, Nayak, Manoswini, Lin, Yan Ren, Li, Thomas Tien-Hsiung, and Wu, Tung-Kung
- Subjects
- *
HALOPHILIC microorganisms , *GASTROENTERITIS , *SEPSIS , *CRYSTALS , *TOXINS - Abstract
Vibrio hollisae, a halophilic species recently reclassified as Grimontia hollisae, is a causative agent of gastroenteritis and septicaemia. One important pathogenic Vibrio factor, thermostable direct haemolysin (TDH), has been purified and crystallized in two crystal forms using the vapour-diffusion method. The crystals belonged to an orthorhombic space group, with unit-cell parameters a = 104.8, b = 112.4, c = 61.3 Å and a = 122.9, b = 123.3, c = 89.8 Å. The crystals contained either four or eight molecules per asymmetric unit, with predicted solvent contents of 49.4 and 46.3% and Matthews coefficients ( VM) of 2.4 and 2.3 Å3 Da−1, respectively. These crystals were suitable for structure determination, which would yield structural details related to the cytotoxicity and oligomeric structure of this pore-forming toxin. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
41. Polymorphisms in metabolic GSTP1 and DNA-repair XRCC1 genes with an increased risk of DNA damage in pesticide-exposed fruit growers
- Author
-
Wong, Ruey-Hong, Chang, Shu-Yuan, Ho, Shu-Wei, Huang, Pei-Lin, Liu, Yi-Jie, Chen, Yu-Ching, Yeh, Yu-Hsuan, and Lee, Hong-Shen
- Subjects
- *
GENETIC polymorphisms , *DNA repair , *PESTICIDES , *HUMAN abnormalities - Abstract
Abstract: Pesticide exposure is associated with various neoplastic diseases and congenital malformations. Previous studies have indicated that pesticides may be metabolized by cytochrome P450 3A5 or glutathione S-transferases. DNA-repair genes, including X-ray repair cross-complementing group 1 (XRCC1) and xeroderma pigmentosum group D (XPD), may also be implicated in the process of pesticide-related carcinogenesis. Thus, we investigated whether various metabolic and DNA-repair genotypes increase the risk of DNA damage in pesticide-exposed fruit growers. Using the comet assay, the extent of DNA damage was evaluated in the peripheral blood of 135 pesticide-exposed fruit growers and 106 unexposed controls. The metabolic genotypes CYP3A5 (A −44 G) and GSTP1 (Ile105Val) and DNA-repair genotypes XRCC1 (Arg399Gln, Arg194Trp, T −77 C) and XPD (Asp312Asn, Lys751Gln) were identified by polymerase chain reaction. Our multiple regression model for DNA tail moment showed that age, high pesticide exposure, low pesticide exposure, GSTP1 Ile-Ile, and XRCC1 399 Arg-Arg genotype were associated with increased DNA tail moment (DNA damage). Further analysis of interaction between GSTP1 and XRCC1 genes that increase susceptibility revealed a significant difference in DNA tail moment for high pesticide-exposed subjects carrying both GSTP1 Ile-Ile with XRCC1 399 Arg-Arg genotypes (2.49±0.09μm/cell; P =0.004), compared to those carrying GSTP1 Ile-Val/Val-Val with XRCC1 399 Arg-Gln/Gln-Gln genotypes (1.98±0.15μm/cell). These results suggest that individuals with susceptible metabolic GSTP1 and DNA-repair XRCC1 genotypes may be at increased risk of DNA damage due to pesticide exposure. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
42. Purification, crystallization and preliminary X-ray crystallographic analysis of xylose reductase from Candida tropicalis.
- Author
-
Chen, Li-Chun, Huang, Sheng-Cih, Chuankhayan, Phimonphan, Chen, Chung-Der, Huang, Yen-Chieh, Jeyakanthan, Jeyaraman, Pang, Hsiao-Fang, Men, Lee-Chung, Chen, Yu-Ching, Wang, Yu-Kuo, Liu, Ming-Yih, Wu, Tung-Kung, and Chen, Chun-Jung
- Subjects
- *
CANDIDA tropicalis , *CRYSTALLIZATION , *X-ray crystallography , *XYLOSE reductase , *XYLITOL - Abstract
Xylose reductase (XR), which requires NADPH as a co-substrate, catalyzes the reduction of d-xylose to xylitol, which is the first step in the metabolism of d-xylose. The detailed three-dimensional structure of XR will provide a better understanding of the biological significance of XR in the efficient production of xylitol from biomass. XR of molecular mass 36.6 kDa from Candida tropicalis was crystallized using the hanging-drop vapour-diffusion method. According to X-ray diffraction data from C. tropicalis XR crystals at 2.91 Å resolution, the unit cell belongs to space group P31 or P32. Preliminary analysis indicated the presence of four XR molecules in the asymmetric unit, with 68.0% solvent content. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.