Up regulation of iNOS gene expression is playing a role in the initiation of the anti-inflammatory and tissue protective
mechanisms related to nitric oxide (NO) for continuous wave red and infrared as well as 905nm superpulsed laser
therapy (SPLT). The iNOS expression before and after laser therapy was evaluated in a zymosan-induced acute arthritis
model, in knee joints of young (<15 weeks), middle aged (>15 weeks and < 35 weeks) and old (> 35 weeks) FVB/N-Tg
(iNOS-luc) mice by bioluminescence imaging.
We present a method for tissue fluorescence quantification in situ using a handheld fiber optic probe that measures both the fluorescence and diffuse reflectance spectra. A simplified method to decouple the fluorescence spectrum from distorting effects of the tissue optical absorption and scattering is developed, with the objective of accurately quantifying the fluorescence in absolute units. The primary motivation is measurement of 5-aminolevulinic acid-induced protoporphyrin IX (ALA-PpIX) concentration in tissue during fluorescence-guided resection of malignant brain tumors. This technique is validated in phantoms and ex vivo mouse tissues, and tested in vivo in a rabbit brain tumor model using ALA-PpIX fluorescence contrast.
Bioluminescence Imaging (BLI) has been employed as an imaging modality to identify and characterize
fundamental processes related to cancer development and response at cellular and molecular levels. This
technique is based on the reaction of luciferin with oxygen in the presence of luciferase and ATP. A major
concern in this technique is that tumors are generally hypoxic, either constitutively and/or as a result of
treatment, therefore the oxygen available for the bioluminescence reaction could possibly be reduced to
limiting levels, and thus leading to underestimation of the actual number of luciferase-labeled cells during in
vivo procedures. In this report, we present the initial in vitro results of the oxygen dependence of the
bioluminescence signal in rat gliosarcoma 9L cells tagged with the luciferase gene (9Lluc cells).
Bioluminescence photon emission from cells exposed to different oxygen tensions was detected by a sensitive
CCD camera upon exposure to luciferin. The results showed that bioluminescence signal decreased at
administered pO2 levels below about 5%, falling by approximately 50% at 0.2% pO2. Additional experiments
showed that changes in BLI was due to the cell inability to maintain normal levels of ATP during the hypoxic
period reducing the ATP concentration to limiting levels for BLI.
This study investigates the efficacy of low level laser therapy (LLLT) in modulating inducible nitric oxide synthase (iNOS) expression as molecular marker of the inflammation signaling pathway. LLLT was mediated by different therapeutic wavelengths using transgenic animals with the luciferase gene under control of the iNOS gene expression. Inflammation in 30 transgenic mice (iNOS-luc mice, from FVB strain) was induced by intra-articular injection of Zymosan-A in both knee joints. Four experimental groups were treated with one of four different wavelengths (λ=635, 785, 808 and 905nm) and one not laser-irradiated control group. Laser treatment (25 mW cm-2, 5 J cm-2) was applied to the knees 15 minutes after inflammation induction. Measurements of iNOS expression were performed at multiple times (0, 3, 5, 7, 9 and 24h) post-LLLT by measuring the bioluminescence signal using a highly sensitive charge-coupled device (CCD) camera.
The responsivity of BLI was sufficient to demonstrate a significant increase in bioluminescence signals after laser irradiation of 635nm when compared to non-irradiated animals and the other LLLT treated groups, showing the wavelength-dependence of LLLT on iNOS expression during the acute inflammatory process.
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