Browsing by Author "Chang, Chien-Jung"

Now showing 1 - 5 of 5

Ablation of androgen receptor gene triggers right ventricular outflow tract ventricular tachycardia
(2015-06-15)
Tsai, Wen-Chin
;
Lu, Yen-Yu
;
Chen, Yao-Chang
;
Chang, Chien-Jung
;
Kao, Yu-Hsun
Background: Sex hormones and calcium (Ca2+) regulation play roles in the pathophysiology of ventricular tachycardia from right ventricular outflow tract (RVOT). The purpose of this study was to evaluate whether androgen receptor knockout (ARKO) can increase RVOT arrhythmogenesis through modulating RVOT electrophysiology and Ca2+ homeostasis. Methods: Conventional microelectrodes were used to study the action potential (AP) in RVOT tissues prepared from wild type (WT) and ARKO mice (aged 6-10 months) before and after caffeine (1 mM), isoproterenol (1 mu M), adenosine (10 mu M) and flecainide (5 mu M) administration. The Fluo-3 fluorescence Ca2+ imaging with confocal microscopy and western blots were used to investigate intracellular Ca2+ (Ca-i(2+)) transients, Ca2+ sparks, and the expressions of ionic channel proteins in ARKO and WT RVOT myocytes. Results: We found that ARKO RVOTs (n = 13) had longer AP duration, faster burst firing (5.4 +/- 0.7 vs. 3.4 +/- 0.7 Hz, P < 0.05), and higher incidence of early afterdepolarizations (82% vs. 8%, P < 0.001) than WT RVOTs (n = 11). Adenosine and flecainide can suppress caffeine-or isoproterenol-induced spontaneous rates and burst firing in WT RVOTs, but not in ARKO RVOTs. ARKO RVOT myocytes had a higher frequency (7.7 +/- 2.8 vs. 1.3 +/- 0.4 spark/mm/s, P < 0.05) and incidence (89% vs. 47%, P < 0.05) of Ca2+ sparks, and greater expressions of Cav1.2, NCX, phosphorylated RyR (s2814), phosphorylated phospholamban (Thr17), CAMKII and GRK2 than WT RVOT myocytes. However, ARKO andWT RVOT myocytes exhibit similar Ca-i(2+) transients and SR Ca2+ content, and less expression of calsequestrin. Conclusions: ARKO changes RVOT electrophysiology and Ca2+ homeostasis with increased ventricular arrhythmogenesis. (C) 2015 Elsevier Ireland Ltd. All rights reserved.
Clinical outcomes of infrarenal abdominal aortic aneurysms that underwent endovascular repair in a district general hospital
(2016-07)
Lee, Chih-Hsien
;
Chang, Chien-Jung
;
Huang, Jau-Kang
;
Yang, Ten-Fang
;
生物科技學系
Background: The purpose of this study was to compare the outcomes of elective endovascular abdominal aortic aneurysm repair (EVAR) and ruptured abdominal aortic aneurysm (rAAA) in patients at a district general hospital. Methods: A retrospective clinical study was conducted using data on 16 patients with elective abdominal aortic aneurysm (AAA) and nine patients with consecutive rAAA treated with EVAR from January 2010 to December 2014 in a district general hospital in Taiwan. Results: The preoperative characteristics of the two groups are listed. Thirty-six percent (9/25) of the patients were referred from other hospitals that did not offer surgical services. The percentage of patients with rAAA that were transferred from other hospitals was 55.5% (5/9). The stay durations in the intensive care unit for elective EVAR cases were shorter than those for emergent EVAR (1.75 +/- 1 d elective vs. 10 +/- 13.37 d emergent; P<0.019). The hospitalization days (11.06 +/- 4.07 d elective vs. 21.89 +/- 18.36 d emergent; P<0.031), operative time (183.63 +/- 57.24 min elective vs. 227.11 +/- 59.92 min emergent; P<0.009), and blood loss volumes (115.63 +/- 80.41 mL elective vs. 422.22 +/- 276.26 mL emergent; P<0.005) are shown; statistics for use of Perclose ProGlide (R) (7 cases elective vs. 0 case emergent; P<0.024) are compared. The overall 30-d mortality rate was 11.11% (1/9). Conclusions: The results confirm that EVAR surgery can be safely performed in a district general hospital with an integrated health care system. Using Perclose ProGlide (R) for selected cases may reduce blood loss and operative time.
Posture and Gender Differentially Affect Heart Rate Variability of Symptomatic Mitral Valve Prolapse and Normal Adults
(2016-07)
Chang, Chien-Jung
;
Chen, Ya-Chu
;
Lee, Chih-Hsien
;
Yang, Ing-Fang
;
Yang, Ten-Fang
Background: Heart rate variability (HRV) has been shown to be a useful measure of autonomic activity in healthy and mitral valve prolapsed (MVP) subjects. However, the effects of posture and gender on HRV in symptomatic MVP and normal adults had not been elucidated in Taiwan. Methods: A total of 118 MVP patients (7 males, 39 +/- 7 years old; and 111 females, 42 +/- 13 years old) and 148 healthy control (54 males, 28 +/- 4 years old; and 94 females, 26 +/- 6 years old) were investigated. The diagnosis of MVP was confirmed by cross-sectional echocardiography. A locally developed Taiwanese machine was used to record the HRV parameters for MVP and control groups in three stationary positions. Thereafter, the HRV time-domain parameters, and the frequency-domain parameters derived from fast Fourier transform or autoregressive methods were analyzed. Results: The MVP group showed a decrease in time domain parameters and obtunded postural effects on frequency domain parameters moreso than the control group. Though the parasympathetic tone was dominant in female (higher RMSSD, nHF and lower nLF vs. male), the sympathetic outflow was higher in MVP female (lower SDNN, NN50 and higher nLF vs. normal female). While the parasympathetic activity was lower in male, sympathetic outflow was dominant in MVP male (lower nHF and higher nLF vs. normal male). Conclusions: Both MVP female and male subjects had elevated levels of sympathetic outflow. The obtunded postural effects on frequency domain measures testified to the autonomic dysregulation of MVP subjects.
Selective and non-selective non-steroidal anti-inflammatory drugs differentially regulate pulmonary vein and atrial arrhythmogenesis
(2015-04-01)
Chang, Chien-Jung
;
Cheng, Chen-Chuan
;
Yang, Ten-Fang
;
Chen, Yao-Chang
;
Lin, Yung-Kuo
Background: Non-steroidal anti-inflammatory drugs (NSAIDs) increase the risk of atrial fibrillation (AF). This study investigated whether selective and non-selective NSAIDs differentially regulate the arrhythmogenesis of pulmonary veins and atria. Methods: Conventional microelectrodes were used to record action potentials (APs) in isolated rabbit PVs, sinoatrial node (SAN), left atrium (LA), and right atrium (RA) preparations before and after celecoxib or indomethacin administration. A whole-cell patch clamp was used to record the sodium-calcium exchanger (NCX) current, L-type calcium current (ICa-L), and late sodium current (INa-late) before and after celecoxib administration in isolated PV cardiomyocytes. Results: Celecoxib (0.3, 1, and 3 mu M) reduced PV spontaneous beating rates, and induced delayed afterdepolarizations and burst firings in four of eight PV preparations (50%, p < 0.05). Celecoxib also reduced SAN beating rates and decreased AP durations (APDs) in RA and LA, but did not change the resting membrane potential. Indomethacin (0.3, 1, 3, and 10 mu M) changed neither the PV or SAN beating rates nor RA APDs, but it reduced LA APDs. Celecoxib (3 mu M) significantly increased the NCX current and decreased the ICa-L, but did not change the INa-late. Ranolazine (10 mu M) suppressed celecoxib (3 mu M)-induced PV burst firings in 6 (86%, p < 0.05) of 7 PVs. KB-R7943 (10 mu M) suppressed celecoxib (3 mu M)-induced PV burst firings in 5 (71%, p < 0.05) of 7 PVs. Conclusions: Selective and non-selective NSAIDs differentially modulate PV and atrial electrophysiological characteristics. Celecoxib increased PV triggered activity through enhancement of the NCX current, which contributed to its arrhythmogenesis. (C) 2015 Elsevier Ireland Ltd. All rights reserved.
Sitagliptin Modulates the Electrical and Mechanical Characteristics of Pulmonary Vein and Atrium
(2014-01-01)
Chang, Chien-Jung
;
Yang, Ten-Fang
;
Lee, Tin-I
;
Chen, Yao-Chang
;
Kao, Yu-Hsun
Background:The pulmonary veins (PVs) and atria are important foci during that period when atrial fibrillation (AF) is generated and maintained. It is well understood that hypertension and diabetes mellitus (DM) are important risk factors for AF. Dipeptidyl peptidase-IV (DPP-4) inhibitors are new agents in the fight against type 2 DM, though they have been found to have several cardiovascular effects. However, it is not clear whether DPP-4 may modulate the electrical and mechanical characteristics in hypertensive atrium or PVs. Methods: Conventional microelectrodes were used to record the action potentials (APs) in isolated PVs, right atrium (RA), and left atrium (LA) in Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) with or without sitagliptin (10 mg/kg) for 4 weeks. Results: WKY (n = 5), SHR (n =7), sitagliptin-treated WKY (n = 5) and sitagliptin-treated SHR (n = 7) had similar PV or sinoatrial spontaneous beating rates. However, the sitagliptin-treated WKY had fewer sinoatrial-PV beating rate differences than WKY, SHR or sitagliptin-treated SHR. WKY and SHR had shorter 90% (APD90) of RA AP duration than sitagliptin-treated WKY or sitagliptin-treated SHR. In contrast, WKY had longer LA APD90 than sitagliptintreated WKY, but SHR and sitagliptin-treated SHR had similar LA APD90. Sitagliptin-treated WKY or sitagliptintreated SHR had larger (RA-LA) APD90 differences than WKY or SHR, respectively. Moreover, as compared to WKY the post-rest potentiation of contraction was decreased in SHR, sitagliptin-treated WKY, and sitagliptin-treated SHR. Conclusions: Sitagliptin significantly affects the electromechanical characteristics of PVs and atria, which can be modulated by hypertension.