Browsing by Author "Chang, Wei-Tien"

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Characterization of the Mechanodynamic Response of Cardiomyocytes with Atomic Force Microscopy
(2013-02-05)
Chang, Wei-Tien
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Yu, David
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Lai, Yu-Cheng
;
Lin, Kuen-You
;
Liau, Ian
Characterization of the Mechanodynamic Response of Cardiomyocytes with Atomic Force Microscopy
Characterization of the Pharmaceutical Effect of Drugs on Atherosclerotic Lesions in Vivo Using Integrated Fluorescence Imaging and Raman Spectral Measurements
(2014-04-15)
Yang, Yi-Cyun
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Chang, Wei-Tien
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Huang, Shao-Kang
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Liau, Ian
;
應用化學系
Direct assessment of the vascular lesions of model animals in vivo is important for the development of new antiatherosclerotic drugs. Nevertheless, biochemical analysis of the lipid profile in blood in vitro remains the most common way to evaluate the therapeutic effect of drugs targeting atherosclerosis because of an inherent difficulty to access the vascular wall. Using hypercholesterolemic zebrafish, we present an orchestrated application of Raman spectral measurements and confocal fluorescence imaging to interrogate the pharmacological response of atherosclerotic lesions in situ and in vivo. For demonstration, we investigated two commonly prescribed antihyperlipidemic drugs, ezetimibe and atorvastatin. The treatment of ezetimibe or atorvastatin alone decreased effectively the deposition of lipids in the vascular wall, and a combined dose showed a synergistic effect. Atorvastatin exerted a profound antioxidative effect on vascular fatty lesions. Analysis of individual lesions shows further that these lesions exhibited a heterogeneous response to the treatment of atorvastatin; a significant fraction of, but not all, the lesions became nonoxidized after the intervention. Beyond its efficacies in suppressing both the accumulation and oxidation of vascular lipids, atorvastatin expedited the clearance of vascular lipids. The possession of pleotropic (multiple) therapeutic effects on vascular fatty lesions of hypercholesterolemic zebrafish by atorvastatin is notably consistent with the known pharmaceutical effects of this drug on human beings. These results improve our understanding of the antiatherosclerotic effect of drugs. We envisage that our approach has the potential to become a platform to predict the pharmaceutical effects of new drugs aiming to cure human atherosclerotic diseases.
Integrated multiple multi-photon imaging and Raman spectroscopy for characterizing structure-constituent correlation of tissues
(2008-10-13)
Jhan, Jhen-Wei
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Chang, Wei-Tien
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Chen, Hung-Che
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Lee, Yu-Tsung
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Wu, Ming-Fang
Histopathological imaging of tissues often requires extensive sample preparation including fixation and staining in order to highlight characteristic alterations associated with diseases. Herein, we report an integrated spectro-microscopy approach based on a combination of multimodal multi-photon imaging and Raman micro-spectroscopy and demonstrate label-free characterization of the structure-constituent correlation of porcine skin. The multi-modal imaging allows the visualization of dermatological features whereas Raman micro-spectroscopy enables the identification of their 'molecular fingerprints'. By obtaining both structural and molecular-level information of tissue constituents, this integrated approach can offer new insight into the patho-physiological status of tissues. (c) 2008 Optical Society of America
Molecular Imaging of Ischemia and Reperfusion in Vivo with Mitochondria! Autofluorescence
(2014-05-20)
Lu, Hsueh-Han
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Wu, Yao-Ming
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Chang, Wei-Tien
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Luo, Teng
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Yang, Yi-Cyun
Ischemia and reperfusion (IR) injury constitutes a pivotal mechanism of tissue damage in pathological conditions such as stroke, myocardial infarction, vascular surgery, and organ transplant. Imaging or monitoring of the change of an organ at a molecular level in real time during IR is essential to improve our understanding of the underlying pathophysiology and to guide therapeutic strategies. Herein, we report molecular imaging of a rat model of hepatic IR with the autofluorescence of mitochondrial flavins. We demonstrate a revelation of the histological characteristics of a liver in vivo with no exogenous stain and show that intravital autofluorescent images exhibited a distinctive spatiotemporal variation during IR. The autofluorescence decayed rapidly from the baseline immediately after 20-min ischemia (approximately 30% decrease in 5 mm) but recovered gradually during reperfusion (to approximately 99% of the baseline 9 mm after the onset of reperfusion). The autofluorescent images acquired during reperfiision correlated strongly with the reperfused blood flow. We show further that the autofluorescence was produced predominantly from mitochondria, and the distinctive autofluorescent variation during IR was mechanically linked to the altered balance between the flavins in the oxidized and reduced forms residing in the mitochondrial electron-transport chain. Our approach opens an unprecedented route to interrogate the deoxygenation and reoxygenation of mitochondria, the machinery central to the pathophysiology of IR injury, with great molecular specificity and spatiotemporal resolution and can be prospectively translated into a medical device capable of molecular imaging. We envisage that the realization thereof should shed new light on clinical diagnostics and therapeutic interventions targeting IR injuries of not only the liver but also other vital organs including the brain and heart.
Optical assessment of the cardiac rhythm of contracting cardiomyocytes in vitro and a pulsating heart in vivo for pharmacological screening
(2014-05-01)
Lai, Yu-Cheng
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Chang, Wei-Tien
;
Lin, Kuen-You
;
Liau, Ian
;
應用化學系
Our quest in the pathogenesis and therapies targeting human heart diseases requires assessment of the contractile dynamics of cardiac models of varied complexity, such as isolated cardiomyocytes and the heart of a model animal. It is hence beneficial to have an integral means that can interrogate both cardiomyocytes in vitro and a heart in vivo. Herein we report an application of dual-beam optical reflectometry to determine noninvasively the rhythm of two representative cardiac models-chick embryonic cardiomyocytes and the heart of zebrafish. We probed self-beating cardiomyocytes and revealed the temporally varying contractile frequency with a short-time Fourier transform. Our unique dual-beam setup uniquely records the atrial and ventricular pulsations of zebrafish simultaneously. To minimize the cross talk between signals associated with atrial and ventricular chambers, we particularly modulated the two probe beams at distinct frequencies and extracted the signals specific to individual cardiac chambers with phase-sensitive detection. With this setup, we determined the atrio-ventricular interval, a parameter that is manifested by the electrical conduction from the atrium to the ventricle. To demonstrate pharmacological applications, we characterized zebrafish treated with various cardioactive and cardiotoxic drugs, and identified abnormal cardiac rhythms and atrioventricular (AV) blocks of varied degree. In light of its potential capability to assess cardiac models both in vitro and in vivo and to screen drugs with cardioactivity or toxicity, we expect this approach to have broad applications ranging from cardiopharmacology to developmental biology. (C) 2014 Optical Society of America
Optical biopsy of atherosclerotic lesions using integrated second-harmonic and nonlinear Raman microscopy
(2008-06-01)
Chang, Wei-Tien
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Jhan, Jhen-Wei
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Wu, Yao-Ming
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Chen, Hung-Che
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Liau, Ian
Predicting the outcomes for out-of-hospital cardiac arrest patients using multiple biomarkers and suspension microarray assays
(2016-06-03)
Huang, Chien-Hua
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Tsai, Min-Shan
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Chien, Kuo-Liong
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Chang, Wei-Tien
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Wang, Tzung-Dau
Predicting the prognosis for cardiac arrest is still challenging. Combining biomarkers from diverse pathophysiological pathways may provide reliable indicators for the severity of injury and predictors of long-term outcomes. We investigated the feasibility of using a multimarker strategy with key independent biomarkers to improve the prediction of outcomes in cardiac arrest. Adult out-of-hospital cardiac arrest patients with sustained return of spontaneous circulation were prospectively enrolled in this study. Blood samples were taken at 2 and 24 hours after cardiac arrest. Suspension microarray assays were used to test 21 different biomarkers. A total of 99 patients were enrolled, 45 of whom survived to hospital discharge. We identified 11 biomarkers that, when combined with clinical variables and factors of APACHE II score and history of arrhythmia, were independent determinants for outcome of in-hospital mortality (concordance = 0.9249, standard error = 0.0779). Three biomarkers combined with APACHE II and age were independent determinants for favorable neurological outcome at hospital discharge (area under the receiver-operator characteristic curve, 0.938; 95% confidence interval, 0.854 similar to 1.0). In conclusion, a systemic multiple biomarker approach using suspension microarray assays can identify independent predictors and model the outcomes of cardiac arrest patients during the post-cardiac arrest period.
Quantitative Assessment of Hepatic Fat of Intact Liver Tissues with Coherent Anti-Stokes Raman Scattering Microscopy
(2009-02-15)
Wu, Yao-Ming
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Chen, Hung-Che
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Chang, Wei-Tien
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Jhan, Jhen-Wei
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Lin, Hung-Lung
A fatty liver might progress from being a benign fatty liver, to steatohepatitis, cirrhosis, or even hepatocellular carcinoma. The great prevalence and severe outcome have warranted much investigation of the pathology and the development of effective therapies, which involve animal studies requiring critical evaluation of the hepatic fatty change. Histological examination and wet chemical analysis of liver biopsy specimens are generally employed for this purpose despite numerous procedures being involved. Using coherent anti-Stokes Raman scattering (CARS) microscopy, we have demonstrated the specific imaging of fat droplets in intact liver tissues and extracted the hepatic fat content through image analysis while eliminating laborious procedures required by traditional histopathological. examination. The content of hepatic fat measured with CARS imaging was correlated strongly with that determined by biochemical analysis (R(2) = 0.89) over a pathologically significant range of the hepatic fat (from 2% to 20% of the total mass of tissue). Our work validates the quantitative assessment of fat in intact tissue through the use of CARS microscopy. When combined with the increasingly diverse animal models of diseases related to metabolic disorders of lipids, our approach is extensible to enable acquiring important insight into the genetic, environmental, and dietary factors affecting the uptake and accumulation of fat within tissues.
Real-Time Microscopic Assessment of Ischemia-Reperfusion with Intravital Autofluorescence Imaging
(2012-11-20)
Lu, Hsueh-Han
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Chang, Wei-Tien
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Wu, Yao-Ming
;
Liau, Ian
;
應用化學系
Real-time molecular assessment on oxidative injury of single cells using Raman spectroscopy
(2009-09-01)
Chang, Wei-Tien
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Lin, Hung-Lung
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Chen, Hung-Che
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Wu, Yao-Ming
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Chen, Wen-Jone
Oxidative stress is encountered in many biological systems; the resultant oxidative injury plays a significant role in the pathogenesis of diverse diseases. Conventional measurements on oxidative injury are employed almost exclusively on a large population of cells either by counting the fraction of cell death or by observing the fluorometric change resulting from exogenous reagents, thereby lacking in molecular detail and temporal specificity. In this work we combine laser tweezers and Raman spectroscopy to observe the response of single cells to oxidative stress. By measuring the temporal changes of vibrational spectra of single optically trapped cells, we demonstrate a molecular-level assessment of cellular oxidative injury in real time, both qualitatively and quantitatively, without the introduction of exogenous reagents. The main experimental findings are supported by the observation of Raman spectra of intermediates and downstream products. The abrogation of the above changes by ascorbic acid further illustrates the therapeutic effect of antioxidants against cellular oxidative injury. This approach is extensible to studies exploring the biochemical transformation of single cells or intracellular organelles in response to various chemical or physical stimuli. With the aid of 'molecular fingerprints', single-cell Raman spectroscopy exhibits a great potential for accessing the chemical aspects of cellular bioactivity, yielding insight into pathophysiological processes and assisting the development of novel therapeutic interventions against diseases. Copyright (C) 2009 John Wiley & Sons, Ltd.
Spatiotemporal Characterization of Phagocytic NADPH Oxidase and Oxidative Destruction of Intraphagosomal Organisms in Vivo Using Autofluorescence Imaging and Raman Microspectroscopy
(2010-02-17)
Chang, Wei-Tien
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Yang, Yi-Cyun
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Lu, Hsueh-Han
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Li, I-Lin
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Liau, Ian
The ability to generate antimicrobial reactive-oxygen species (ROS) by reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is critical for the host to defend against invading microbes. We have demonstrated the application of confocal autofluorescence microscopy and Raman microspectroscopy to characterize dynamically the phagocytic process of living macrophages in a label-free manner. In particular, we visualized the translocation of NADPH oxidases in livin macrophages that are undergoing phagocytosis of invading yeasts and monitored dynamically the change at the molecular level of single intraphagosomal yeasts caused by phagocytic ROS.
The difference in myocardial injuries and mitochondrial damages between asphyxial and ventricular fibrillation cardiac arrests
(2012-10-01)
Tsai, Min-Shan
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Huang, Chien-Hua
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Tsai, Shang-Ho
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Tsai, Chia-Ying
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Chen, Huei-Wen
Introduction: Ventricular fibrillation (VF) and asphyxia account for most cardiac arrests but differ in cardiac arrest course, neurologic deficit, and myocardial damage. In VF resuscitation, cardiac mitochondria were known to be damaged via excess generation of reactive oxygen species. This study evaluated the difference of cardiac mitochondrial damages between VF and asphyxial cardiac arrests. Methods: In the VF + electrical shock (ES) group, VF was induced and untreated for 5 minutes, followed by 1 minute of cardiopulmonary resuscitation (CPR) and 1 ES of 5 J. Animals were killed immediately after ES. In the asphyxia group, cardiac arrest was induced by airway obstruction, and then pulselessness was maintained for 5 minutes, followed by 1 minute of CPR. The animals were killed immediately after CPR. The histology and ultrastructural changes of myocardium and complex activities and respiration of mitochondria were evaluated. The mitochondrial permeability transition pore opening was measured based on mitochondrial swelling rate. Results: The histopathologic examinations showed myocardial necrosis and mitochondrial damage in both cardiac arrests. Instead of regional damages of myocardium in the VF + ES group, the myocardial injury in the asphyxia group distributed diffusely. The asphyxia group demonstrated more severe mitochondrial damage than the VF + ES group, which had a faster mitochondrial swelling rate, more decreased cytochrome c oxidase activity, and more impaired respiration. Conclusions: Both VF and asphyxial cardiac arrests caused myocardial injuries and mitochondrial damages. Asphyxial cardiac arrest presented more diffuse myocardial injuries and more severe mitochondrial damages than VF cardiac arrest. (c) 2012 Elsevier Inc. All rights reserved.
Toward Functional Screening of Cardioactive and Cardiotoxic Drugs with Zebrafish in Vivo Using Pseudodynamic Three-Dimensional Imaging
(2014-02-18)
Lin, Kuen-You
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Chang, Wei-Tien
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Lai, Yu-Cheng
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Liau, Ian
;
應用化學系
Given the high mortality in patients with cardiovascular diseases and the life-threatening consequences of drugs with unforeseen adverse effects on hearts, a critical evaluation of the pharmacological response of cardiovascular function on model animals is important especially in the early stages of drug development. We report a proof-of-principle study to demonstrate the utility of zebrafish as an analytical platform to predict the cardiac response of new drugs or chemicals on human beings. With pseudodynamic 3D imaging, we derive individual parameters that are central to the cardiac function of zebrafish, including the ventricular stroke volume, ejection fraction, cardiac output, heart rate, diastolic filling function, and ventricular mass. We evaluate both inotropic and chronotropic responses of the heart of zebrafish treated with drugs that are commonly prescribed and possess varied known cardiac activities. We reveal deranged cardiac function of a zebrafish model of cardiomyopathy induced with a cardiotoxic drug. The cardiac function of zebrafish exhibits a pharmacological response similar to that of human beings. We compare also cardiac parameters obtained in this work with those derived with conventional 2D approximation and show that the latter tends to overestimate the cardiac parameters and produces results of greater variation. In view of the growing interest of using zebrafish in both fundamental and translational biomedical research, we envisage that our approach should benefit not only contemporary pharmaceutical development but also exploratory research such as gene, stem cell, or regenerative therapies targeting congenital or acquired heart diseases.
Zebrafish model of photochemical thrombosis for translational research and thrombolytic screening in vivo
(2017-04-01)
Lee, I-Ju
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Yang, Yi-Cyun
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Hsu, Jia-Wen
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Chang, Wei-Tien
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Chuang, Yung-Jen
Acute thromboembolic diseases remain the major global cause of death or disability. Although an array of thrombolytic and antithrombotic drugs has been approved to treat or prevent thromboembolic diseases, many more drugs that target specific clotting mechanisms are under development. Here a novel zebrafish model of photochemical thrombosis is reported and its prospective application for the screening and preclinical testing of thrombolytic agents in vivo is demonstrated. Through photochemical excitation, a thrombus was induced to form at a selected section of the dorsal aorta of larval zebrafish, which had been injected with photosensitizers. Such photochemical thrombosis can be consistently controlled to occlude partially or completely the targeted blood vessel. Detailed mechanistic tests indicate that the zebrafish model of photochemical thrombosis exhibits essential features of classical coagulation and a thrombolytic pathway. For demonstration, tissue plasminogen activator (tPA), a clinically feasible thrombolytic agent, was shown to effectively dissolve photochemically induced blood clots. In light of the numerous unique advantages of zebrafish as a model organism, our approach is expected to benefit not only the development of novel thrombolytic and antithrombotic strategies but also the fundamental or translational research targeting hereditary thrombotic or coagulation disorders.