Browsing by Author "Li, Liming"

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Effects of Nanosecond Pulsed Electric Field on Intracellular NADH Autofluorescence: A Comparison between Normal and Cancer Cells
(2017-06-01)
Awasthi, Kamlesh
;
Nakabayashi, Takakazu
;
Li, Liming
;
Ohta, Nobuhiro
;
應用化學系
Intracellular fluorescence lifetime and intensity images of the endogenous fluorophore of nicotinamide adenine dinucleotide (NADH) have been observed before and after application of nanosecond pulsed electric field (nsPEF) in normal and cancer cells, that is, in Wistar-KingAptekman rat fetus fibroblast (WFB) cells and W31 cells, which are the malignant transformed cells from WFB. The application of nsPEF induces a change both in intensity and lifetime of NADH, indicating that the intracellular function is affected by application of nsPEF in both normal and cancer cells. The application of nsPEF induces an increase in the fluorescence lifetime of NADH and a morphological change, which is attributed to the induction of apoptosis by nsPEF. The field effect on the intensity and lifetime clearly depends on the pulse width, and magnitude of the field-induced increase in the fluorescence lifetime of NADH has a tendency to increase with a decreasing pulse width. It is also found that apoptosis can be induced only in cancer cells using a suitable nsPEF, showing a possibility that ultrashort pulsed electric field is applicable for drugfree cancer therapy.
Sensitive detection of intracellular environment of normal and cancer cells by autofluorescence lifetime imaging
(2016-12)
Awasthi, Kamlesh
;
Moriya, Daiki
;
Nakabayashi, Takakazu
;
Li, Liming
;
Ohta, Nobuhiro
Intracellular fluorescence lifetime images of the endogenous fluorophores of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD), which are well known as autofluorescence chromophores, were obtained from rat normal fibroblast cells (WFB) and H-ras oncogene-transfected cancer cells among WFB (W31). The average lifetime of the NADH and FAD autofluorescence was shorter in cancer cells than in normal cells, indicating that the difference in metabolism between healthy and cancer cells alters the conditions for coenzymes such as NADH and FAD and that the autofluorescence lifetime measurement of NADH and FAD is applicable for the noninvasive diagnosis of cancer cells. The pico- and nano-second time-resolved fluorescence spectra of NADH obtained with different time windows were similar in normal and cancer cells, indicating that every fluorescence decay component gives the same spectrum in both cell types. These results as well as the fluorescence lifetime images of exogenous fluorophores stained with sodium pheophorbide a in normal and cancer cells suggest that the difference in the fluorescence lifetime between normal and cancer cells cannot be attributed to a difference in the intracellular pH or refractive index but to the difference in the bound condition between proteins and NADH or FAD under the different intracellular environments of normal and cancer cells. (C) 2016 Elsevier B.V. All rights reserved.