Normal brain tissue response to photodynamic therapy: histology, vascular permeability and specific gravity.
The response of photodynamic therapy on normal brain was investigated in 140 Fisher rats. The rats were injected i.p. with Photofrin II (12.5 mg/kg) and 48 h later the dural area over the frontal cortex was photoactivated with red light (630 +/- 1 nm) from an argon dye laser. Treatment was performed with optical energy densities of 140 and 70 J/cm2. Histopathology, vascular permeability and specific gravity measurements were conducted on different populations of rats at 4 h, 24 h, 72 h and 1 week after photodynamic therapy (PDT). Histopathology revealed similar gross and microscopic pathology associated with light energies of 70 and 140 J/cm2 after all time points. A large cerebral infarct approximately the size of the brain surface area treated, evolved 24 h following treatment. Evans blue extravasation indicated a small area of vascular permeability evident as early as 4 h following PDT treatment at both energy levels, with increasing permeability evident at later time points. Specific gravity measurements taken on a representative area of the lesion indicated a significant (P less than 0.01) amount of edema present at 24 h post treatment with a gradual reduction approaching control values over the time period of 1 week. The data indicate a significant amount of damage to normal brain from low PDT treatment doses.
Dereski
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Chopp
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Chen
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Hetzel
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D000818:Animals; D001921:Brain / Q000098:blood supply / Q000473:pathology; D001927:Brain Diseases / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D001929:Brain Edema / Q000209:etiology / Q000473:pathology; D002545:Brain Ischemia / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D002199:Capillary Permeability; D017323:Dihematoporphyrin Ether; D006415:Hematoporphyrins / Q000633:toxicity*; D007834:Lasers / Q000009:adverse effects*; D008297:Male; D010778:Photochemotherapy / Q000009:adverse effects*; D051381:Rats
D006415:Hematoporphyrins; D017323:Dihematoporphyrin Ether