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Proceedings Paper

Wavelength-dependent dynamics of heat shock protein 70 expression in free electron laser wounds
Author(s): Gerald J. Wilmink; Joshua T. Beckham; Mark Mackanos; Christopher H. Contag; Jeffrey M. Davidson; E. Duco Jansen
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Paper Abstract

Many medical laser procedures require selecting laser operating parameters that minimize undesirable tissue damage. In this study, heat shock protein 70(hsp70) gene expression was used as a sensitive marker for laser-induced thermal damage. Wound repair and hsp70 expression were compared after surgery with the free electron laser(FEL) as a function of wavelength(&lgr;) and radiant exposure(H). Damage was assessed at &lgr; = 6.45, 6.10, and 2.94 &mgr;m using 8-20 J/cm2. The FEL beam (&Vpgr;r=200 &mgr;m,30Hz,&tgr;p =5&mgr;s) was delivered to produce a 6.5 mm square wound. hsp70 expression was assessed using a transgenic mouse strain with the hsp70 promoter driving luciferase and eGFP expression. Bioluminescent imaging (BLI) was monitored non-invasively and in real time. Hsp70 protein was visualized with laser confocal imaging, blood velocity was measured with 2D-laser doppler, and depth of tissue damage was measured using histological methods. BLI verified the model's sensitivity and peak hsp70 expression was bi-phasic, with maxima occurring 12 and 24 hours after FEL irradiation. hsp70 expression exhibited wavelength-dependence, and it increased with radiant exposure. Histology indicated that tissue damage at 6.45 µm was ~2x deeper than 6.10 &mgr;m. Quantitative BLI with the Hsp70-luc transgene can be used to non-invasively measure gene expression in laser-tissue interaction studies.

Paper Details

Date Published: 8 February 2007
PDF: 12 pages
Proc. SPIE 6440, Thermal Treatment of Tissue: Energy Delivery and Assessment IV, 644003 (8 February 2007); doi: 10.1117/12.705085
Show Author Affiliations
Gerald J. Wilmink, Vanderbilt Univ. (United States)
Joshua T. Beckham, Vanderbilt Univ. (United States)
Mark Mackanos, Stanford School of Medicine (United States)
Christopher H. Contag, Stanford School of Medicine (United States)
Jeffrey M. Davidson, Vanderbilt Univ. (United States)
E. Duco Jansen, Vanderbilt Univ. (United States)

Published in SPIE Proceedings Vol. 6440:
Thermal Treatment of Tissue: Energy Delivery and Assessment IV
Thomas P. Ryan, Editor(s)

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