Browsing by Author "Chang, Ya-Ting"

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Characteristics of scrub typhus, murine typhus, and Q fever among elderly patients: Prolonged prothrombin time as a predictor for severity
(2019-02-01)
Chang, Ko
;
Lee, Nan-Yao
;
Ko, Wen-Chien
;
Lin, Wei-Ru
;
Chen, Yen-Hsu
Background/purpose: The clinical manifestations of scrub typhus, murine typhus and acute Q fever in the elderly are not clear. Methods: We conducted a retrospective study to identify the characteristics of the elderly aged >= 65 years with a comparison group aged 18-64 years among patients with scrub typhus, murine typhus, or acute Q fever who were serologically confirmed at three hospitals in Taiwan during 2002-2011. Results: Among 441 cases, including 187 cases of scrub typhus, 166 acute Qfever, and 88 murine typhus, 68 (15.4%) cases were elderly patients. The elderly had a higher severe complication rate (10.3% vs. 3.5%, p = 0.022), but did not have a significantly higher mortality rate (1.47% vs. 0.54%, p = 0.396). Compared with those without severe complications, we found the elderly (p = 0.022), dyspnea (p = 0.006), less relative bradycardia (p = 0.004), less febrile illness (p = 0.004), prolonged prothrombin time (PT) (p = 0.002), higher levels of initial C-reactive protein (p = 0.039), blood leukocyte counts (p = 0.01), and lower platelet counts (p = 0.012) are significantly associated with severe complications. Only prolonged prothrombin time was associated with severe complications in multivariate analysis (p = 0.018, CI 95% 0.01-0.66). Among clinical symptoms and laboratory data, multivariate analysis revealed chills was less frequently occurred in the elderly (p = 0.012, 95% confidence interval [CI]: 1.33-9.99). Conclusion: The elderly cases with scrub typhus, murine typhus, or acute Q fever would be more likely to have severe complications, for which prothrombin time prolongation is an important predictor for severe complications. Copyright (C) 2017, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC.
Complexity-Effective Auditory Compensation with a Controllable Filter for Digital Hearing Aids
(2012)
Chang, Ya-Ting
;
Chang, Kuo-Chiang
;
Kuo, Yu-Ting
;
Liu, Chih-Wei
;
電子工程學系及電子研究所
Auditory compensation consumes significant power due to the computation-intensive operations in the filter bank. To reduce the complexity, a controllable filter was designed to replace the filter bank. Filter order was designed to match prescriptions within a specific error constraint with minimum computational cost. An interpolation scheme according to the variation of signal intensity was implemented to reduce the overhead of coefficients calculations. The proposed auditory compensation reduces 80% of multiplications and 30% of power consumption compared to the complexity-effective multi-rate filter bank architecture [4]. Moreover, the group delay was also reduced from 10 ms to 2.4 ms.
Efficient high-peak-power diode-pumped actively Q-switched Nd:YAG/YVO(4) intracavity Raman laser
(2008-12-10)
Su, Kuan-Wei
;
Chang, Ya-Ting
;
Chen, Yung-Fu
;
電子物理學系
;
Department of Electrophysics
An undoped YVO(4) crystal is employed to achieve efficient stimulated Raman scattering conversion in a diode-pumped actively Q-switched Nd:YAG laser. With an incident pump power of 16.2 W, an 1176 nm first Stokes average output power of 3.0 W was generated at a pulse repetition rate of 50 kHz, corresponding to an optical-to-optical conversion efficiency of 18.3%. Moreover, the maximum optical-to-optical conversion efficiency of 21.3% was found at 20 kHz. The maximum pulse energy is higher than 83 mu J at both 20 and 30 kHz. With an incident pump power of 7.6W, the underestimated peak power of 43.5 kW was demonstrated at 20 kHz with mode-locked modulation. (c) 2008 Optical Society of America
Efficient high-peak-power diode-pumped actively Q-switched Nd:YAG/YVO4 intracavity Raman laser
(2008-12-10)
Su, Kuan-Wei
;
Chang, Ya-Ting
;
Chen, Yung-Fu
;
電子物理學系
;
Department of Electrophysics
An undoped YVO4 crystal is employed to achieve efficient stimulated Raman scattering conversion in a diode-pumped actively Q-switched Nd:YAG laser. With an incident pump power of 16.2 W, an 1176 nm first Stokes average output power of 3.0 W was generated at a pulse repetition rate of 50 kHz, corresponding to an optical-to-optical conversion efficiency of 18.3%. Moreover, the maximum optical-to-optical conversion efficiency of 21.3% was found at 20 kHz. The maximum pulse energy is higher than 83 mu J at both 20 and 30 kHz. With an incident pump power of 7.6W, the underestimated peak power of 43.5 kW was demonstrated at 20 kHz with mode-locked modulation. (c) 2008 Optical Society of America
Epidemiology and trends in the antibiotic susceptibilities of Gram-negative bacilli isolated from patients with intra-abdominal infections in the Asia-Pacific region, 2010-2013
(2017-06-01)
Chang, Ya-Ting
;
Coombs, Geoffrey
;
Ling, Thomas
;
Balaji, V.
;
Rodrigues, Camilla
This study was conducted to investigate the epidemiology and antimicrobial susceptibility patterns of Gram-negative bacilli (GNB) isolated from intra-abdominal infections (IAIs) in the Asia-Pacific region (APR) from 2010-2013. A total of 17 350 isolates were collected from 54 centres in 13 countries in the APR. The three most commonly isolated GNB were Escherichia coli (46.1%), Klebsiella pneumoniae (19.3%) and Pseudomonas aeruginosa (9.8%). Overall, the rates of extended-spectrum beta-lactamase (ESBL)-producing E. coli and K. pneumoniae were 38.2% and 24.3%, respectively, and they were highest in China (66.6% and 38.7%, respectively), Thailand (49.8% and 36.5%, respectively) and Vietnam (47.9% and 30.4%, respectively). During 2010-2013, the rates of ESBL-producing E. coli and K. pneumoniae isolates causing community-associated (CA) IAIs (collected <48 h after admission) were 26.0% and 13.5%, respectively, and those causing hospital-associated (HA) IAIs were 48.0% and 30.6%, respectively. Amikacin, ertapenem and imipenem were the most effective agents against ESBL-producing isolates. Piperacillin/tazobactam displayed good in vitro activity (91.4%) against CA ESBL-producing E. coli. For other commonly isolated Enterobacteriaceae, fluoroquinolones, cefepime and carbapenems exhibited better in vitro activities than third-generation cephalosporins. Amikacin possessed high in vitro activity against all GNB isolates (>80%) causing IAIs, except for Acinetobacter calcoaceticus-baumannii (ACB) complex (30.9% for HA-IAI isolates). All of the antimicrobial agents tested exhibited <45% in vitro activity against ACB complex. Antimicrobial resistance is a persistent threat in the APR and continuous monitoring of evolutionary trends in the susceptibility patterns of GNB causing IAIs in this region is mandatory. (C) 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.
Infections Caused by Carbapenem-Resistant Enterobacteriaceae: An Update on Therapeutic Options
(2019-01-30)
Sheu, Chau-Chyun
;
Chang, Ya-Ting
;
Lin, Shang-Yi
;
Chen, Yen-Hsu
;
Hsueh, Po-Ren
Carbapenems are considered as last-resort antibiotics for the treatment of infections caused by multidrug-resistant Gram-negative bacteria. With the increasing use of carbapenems in clinical practice, the emergence of carbapenem-resistant pathogens now poses a great threat to human health. Currently, antibiotic options for the treatment of carbapenem-resistant Enterobacteriaceae (CRE) are very limited, with polymyxins, tigecycline, fosfomycin, and aminoglycosides as the mainstays of therapy. The need for new and effective anti-CRE therapies is urgent. Here, we describe the current understanding of issues related to CRE and review combination therapeutic strategies for CRE infections, including high-dose tigecycline, high-dose prolonged-infusion of carbapenem, and double carbapenem therapy. We also review the newly available antibiotics which have potential in the future treatment of CRE infections: ceftazidime/avibactam, which is active against KPC and OXA-48 producers; meropenem/vaborbactam, which is active against KPC producers; plazomicin, which is a next-generation aminoglycoside with in vitro activity against CRE; and eravacycline, which is a tetracycline class antibacterial with in vitro activity against CRE. Although direct evidence for CRE treatment is still lacking and the development of resistance is a concern, these new antibiotics provide additional therapeutic options for CRE infections. Finally, we review other potential anti-CRE antibiotics in development: imipenem/relebactam and cefiderocol. Currently, high-dose and combination strategies that may include the new beta-lactam/beta-lactamase inhibitors should be considered in severe CRE infections to maximize treatment success. In the future, when more treatment options are available, therapy for CRE infections should be individualized and based on molecular phenotypes of resistance, susceptibility profiles, disease severity, and patient characteristics. More high-quality studies are needed to guide effective treatment for infections caused by CRE.
Management of infections caused by extended-spectrum -lactamase-producing Enterobacteriaceae: current evidence and future prospects
(2018-01-01)
Sheu, Chau-Chyun
;
Lin, Shang-Yi
;
Chang, Ya-Ting
;
Lee, Chun-Yuan
;
Chen, Yen-Hsu
Introduction: The spread of extended-spectrum -lactamase (ESBL)-producing Enterobacteriaceae has become a major public health threat worldwide.Area covered: A thorough systematic literature review describing the current evidence and future prospects of therapeutic options for infections caused by ESBL-producing Enterobacteriaceae.Expert commentary: The methods of detecting ESBLs have been evolving. The Clinical and Laboratory Standards Institute and the European Committee on Antimicrobial Susceptibility Testing lowered the MIC breakpoints of cephalosporins against ESBL-producing Enterobacteriaceae in 2010. Phenotypic testing for ESBLs is no longer recommended. Instead, the selection of appropriate antimicrobial agents largely depends on the report of minimum inhibitory concentrations (MICs). To date, therapeutic options for these multidrug-resistant organisms remain limited. The clinical efficacy of piperacillin/tazobactam and cefepime on in vitro-susceptible ESBL-producing Enterobacteriaceae remains a concern. Many studies found an in vitro-in vivo discordance based on current breakpoints. Carbapenems are the most reliable antibiotics for severe infections caused by ESBL-producing Enterobacteriaceae. However, their overuse has led to a serious problem of increasing drug resistance. Recently, ceftolozane/tazobactam and ceftazidime/avibactam have been approved for the treatment of complicated urinary tract infections and complicated intra-abdominal infections. The introduction of these new -lactam/-lactamase inhibitor combinations offers new carbapenem-sparing options for the treatment of ESBL infections.
Quantitative Evaluation of Brain Magnetic Resonance Images Using Voxel-based Morphometry and Bayesian Theorem for Patients with Bipolar Disorder
(2008)
Chen, Yong-Sheng
;
Chen, Li-Fen
;
Chang, Ya-Ting
;
Huang, Yung-Tien
;
Su, Tung-Ping
The present diagnosis of bipolar disorder (BD), which mainly depends on patients' symptoms and self reports of past history and mood status, may encounter difficulty of distinguishing from unipolar disorder when patients behave depressively in clinic. This work proposes a novel computer-aided evaluation system for bipolar disorder using anatomic magnetic resonance images (MRI) to provide a second opinion for clinician's diagnosis. First we adopt the voxel-based morphometry method to identify brain regions with significant difference between patient and normal control groups as regions of interest (ROIs). Then the MRI data within these ROIs are processed with principal component analysis (PCA) in order to reduce feature dimensionality. Finally, a classification model based on Bayesian theorem together with Parzen-window density estimation in PCA space is constructed to provide the possibility of an individual belonging to the BD patient group. The proposed system reaches 86.8% accuracy in classification. In our experiment, the misdetection rate was zero, and the false alarm was 15.8%. Through appropriate feature analysis and selection method, this computer-aided system can detect the disease of BD and obtain high classification accuracy.
Update on infections caused by Stenotrophomonas maltophilia with particular attention to resistance mechanisms and therapeutic options
(2015-09-02)
Chang, Ya-Ting
;
Lin, Chun-Yu
;
Chen, Yen-Hsu
;
Hsueh, Po-Ren
;
生醫工程研究所
Stenotrophomonas maltophilia is a Gram-negative, biofilm-forming bacterium. Although generally regarded as an organism of low virulence, S. maltophilia is an emerging multi-drug resistant opportunistic pathogen in hospital and community settings, especially among immunocompromised hosts. Risk factors associated with S. maltophilia infection include underlying malignancy, cystic fibrosis, corticosteroid or immunosuppressant therapy, the presence of an indwelling central venous catheter and exposure to broad spectrum antibiotics. In this review, we provide a synthesis of information on current global trends in S. maltophilia pathogenicity as well as updated information on the molecular mechanisms contributing to its resistance to an array of antimicrobial agents. The prevalence of S. maltophilia infection in the general population increased from 0.8-1.4% during 1997-2003 to 1.3-1.68% during 2007-2012. The most important molecular mechanisms contributing to its resistance to antibiotics include beta-lactamase production, the expression of Qnr genes, and the presence of class 1 integrons and efflux pumps. Trimethoprim/sulfamethoxazole (TMP/SMX) is the antimicrobial drug of choice. Although a few studies have reported increased resistance to TMP/SMX, the majority of studies worldwide show that S. maltophilia continues to be highly susceptible. Drugs with historically good susceptibility results include ceftazidime, ticarcillin-clavulanate, and fluoroquinolones; however, a number of studies show an alarming trend in resistance to those agents. Tetracyclines such as tigecycline, minocycline, and doxycycline are also effective agents and consistently display good activity against S. maltophilia in various geographic regions and across different time periods. Combination therapies, novel agents, and aerosolized forms of antimicrobial drugs are currently being tested for their ability to treat infections caused by this multi-drug resistant organism.