2007 Fiscal Year Final Research Report Summary
Photodynamic effect of photoproduct originated in photosensitizer on experimental tongue squamous cell carcinoma in rat
| Project/Area Number |
18592217
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Surgical dentistry
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| Research Institution | University of Fukui |
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Principal Investigator |
OGASAWARA Toshiyuki University of Fukui, Faculty of Medical Sciences, Associate Professor (20260565)
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| Co-Investigator(Kenkyū-buntansha) |
MIYOSHI Norio University of Fukui, Faculty of Medical Sciences, Assistant Professor (40209961)
SANO Kezuo University of Fukui, Faculty of Medical Sciences, Professor (20145270)
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| Project Period (FY) |
2006 – 2007
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| Keywords | Tongue Cancer / Photodynamic therapy / 5-Aminolevulinic Acid / Protoporphyrin-IX / Photoproduct |
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| Research Abstract |
Purpose: 5-aminolevulinic acid (ALA)-induced protoporphyrinlX (PpIX) has been used as a photosensitizer in photodynamic therapy (PDT) for oral cancer treatment. However, the application of ALA-PDT for oral lesion is limited in relatively early malignant tumor. The Pp-IX is produced in mitochondria of cancer cell after the ALA oral-administration and is activated optimally around 635nm irradiation to induce photodestruction of the malignant lesion. Recently, it is reported that during irradiation of ALA-PDT several photoproducts are formed. Photoprotoporphyrin is the main product with peak absorption around 670nm and is efficient photosensitizer itself. It has therefore been speculated that concomitant irradiation of ALA-sensitized lesions with 635 and adding 670nm light might be more effective in harnessing the therapeutic effects arising from both Pp-IX and its photoproduct.
Material and Method: Malignant lesions of rat oral cavity (tongue, gingiva, palatal mucosa) were used in this st
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udy which was induced by 4-nitroquinoline-l-oxide (4NQ0) administration about for 6 months. At 4h after oral administration of ALA (250mg/kg), the lesions were irradiated with three type of emission wavelength of diode laser. Three type were
(1) 635nm CW (80mW/150J) ; (635nm)
(2) 635nm CW (80mW/150J) + 670nm CW(80mW/ 150J) ; (635nm+670nm)
(3) 635nm CW (80mW/150J) +Pulsed Three Wavelengths ; 659nm 664nm 669nm(42 : 7 : 1) (80mW/150J) ; (635nm+PTW).
Rats were killed at 24h after laser irradiation and oral cancer samples were excised. Ki67 and apoptosis (Apoptag) were examined immunohistochemically for each samples as treatment evaluation.
Conclusion and Discussion: Assessment of decrease of tumor activity and apoptosis revealed efficacy in the 635nm + PMW group compared to 635nm alone group and 635nm+670nm group. This result suggested that concomitant irradiation of ALA-sensitized cancer with 635 nm and adding photoproduct light showed enhancing the therapeutic effects. And it might be considered that 659nm, 664nm 669nm is more effective rather than 670nm.alone for tumor as photodestruction effect of photoproduct. Less
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