Browsing by Author "Lu, Hsueh-Han"

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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
;
Luo, Teng
;
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.
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
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應用化學系
Selective and Absolute Quantification of Endogenous Hypochlorous Acid with Quantum-Dot Conjugated Microbeads
(2011-11-01)
Yang, Yi-Cyun
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Lu, Hsueh-Han
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Wang, Wei-Ti
;
Liau, Ian
;
應用化學系
Endogenous hypochlorous acid (Hod) secreted by leukocytes plays a critical role in both the immune defense of mammalians and the pathogenesis of-various diseases intimately related to inflammation. We report the first selective and absolute quantification of endogenous HOCl produced by leukocytes in vitro and in vivo with a novel quantum dot-based sensor. An activated human neutrophil secreted 6.5 +/- 0.9 x 10(8) HOCl molecules into its phagosome, and kinetic measurement for the secretions showed that the extracellular generation of HOCl was temporally retarded, but the quantity eventually attained a level comparable with its intraphagosomal counterpart with a delay of about 1.5 h. The quantity of HOCl secreted from the hepatic leukocytes of rats with or without stimulation of lipopolysaccharide was also determined. These results indicate a possibility to extend our approach to not only clinical settings for quantitative assessment of the bactericidal capability of isolated leukocytes of patients but also fundamental biomedical research that requires critical evaluation of the inflammatory response of animals.
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
;
Yang, Yi-Cyun
;
Lu, Hsueh-Han
;
Li, I-Lin
;
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.
Toward live-cell imaging of dopamine neurotransmission with fluorescent neurotransmitter analogues
(2015-01-01)
Lin, Hui-Jen
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Lu, Hsueh-Han
;
Liu, Kuan-Miao
;
Chau, Chi-Min
;
Hsieh, You-Zung
We report a novel \'fluorescent dopamine\' that possesses essential features of natural dopamine. Our method is simple and is readily extended to monoamine neurotransmitters such as L-norepinephrine, serotonin and GABA, providing a more practical approach. Because of its compatibility with sensitive fluorescent measurements, we envisage that our approach will have a broad range of applications in neural research.