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Proceedings Paper

Two-photon excitation laser scanning microscopy of porcine nasal septal cartilage following Nd:YAG laser-mediated stress relaxation
Author(s): Charlton C. Kim; Vincent P. Wallace; Alexandre Rasouli; Mariah L. Coleno; Xavier Dao; Bruce J. Tromberg; Brian Jet-Fei Wong
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Paper Abstract

Laser irradiation of hyaline cartilage result in stable shape changes due to temperature dependent stress relaxation. In this study, we determined the structural changes in chondrocytes within porcine nasal septal cartilage tissue over a 4-day period using a two-photon laser scanning microscope (TPM) following Nd:YAG laser irradiation (lambda equals 1.32 micrometer) using parameters that result in mechanical stress relaxation (6.0 W, 5.4 mm spot diameter). TPM excitation (780 nm) result in induction of fluorescence from endogenous agents such as NADH, NADPH, and flavoproteins in the 400 - 500 nm spectral region. During laser irradiation diffuse reflectance (from a probe HeNe laser, (lambda) equals 632.8 nm), surface temperature, and stress relaxation were measured dynamically. Each specimen received one, two, or three sequential laser exposures (average irradiation times of 5, 6, and 8 seconds). The cartilage reached a peak surface temperature of about 70 degrees Celsius during irradiation. Cartilage denatured in 50% EtOH (20 minutes) was used as a positive control. TPM was performed using a mode-locked 780 nm Titanium:Sapphire (Ti:Al203) beam with a, 63X, 1.2 N.A. water immersion objective (working distance of 200 mm) to detect the fluorescence emission from the chondrocytes. Images of chondrocytes were obtained at depths up to 150 microns (lateral resolution equals 35 micrometer X 35 micrometer). Images were obtained immediately following laser exposure, and also after 4 days in culture. In both cases, the irradiated and non-irradiated specimens do not show any discernible difference in general shape or auto fluorescence. In contrast, positive controls (immersed in 50% ethanol), show markedly increased fluorescence relative to both the native and irradiated specimens, in the cytoplasmic region.

Paper Details

Date Published: 17 May 2000
PDF: 9 pages
Proc. SPIE 3907, Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems X, (17 May 2000); doi: 10.1117/12.386233
Show Author Affiliations
Charlton C. Kim, Yale Univ. School of Medicine and Beckman Laser Institute and Medical Clinic (United States)
Vincent P. Wallace, Beckman Laser Institute and Medical Clinic (United Kingdom)
Alexandre Rasouli, Beckman Laser Institute and Medical Clinic (United States)
Mariah L. Coleno, Beckman Laser Institute and Medical Clinic (United States)
Xavier Dao, Beckman Laser Institute and Medical Clinic (United States)
Bruce J. Tromberg, Beckman Laser Institute and Medical Clinic (United States)
Brian Jet-Fei Wong, Beckman Laser Institute and Medical Clinic (United States)

Published in SPIE Proceedings Vol. 3907:
Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems X
R. Rox Anderson; Kenton W. Gregory; Eugene A. Trowers; David S. Robinson; Kenneth Eugene Bartels; Lou Reinisch; Reza S. Malek; C. Gaelyn Garrett; Lloyd P. Tate; Hans-Dieter Reidenbach; Timothy A. Woodward; Kenneth Eugene Bartels; Lawrence S. Bass; George M. Peavy; C. Gaelyn Garrett; Kenton W. Gregory; Nikiforos Kollias; Harvey Lui; Reza S. Malek; George M. Peavy; Hans-Dieter Reidenbach; Lou Reinisch; David S. Robinson; Lloyd P. Tate; Eugene A. Trowers; Timothy A. Woodward, Editor(s)

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