CHAPTER 31: Photodynamic Reactions As a Marker of Cerebral Vascular Diseases
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Published:15 Aug 2016
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Special Collection: 2016 ebook collection
E. Bigot, R. Bourcier, B. Rozec, N. Nighoghossian, T. Ritzenthaler, B. Claustrat, ... T. Patrice, in Photodynamic Medicine: From Bench to Clinic, ed. H. Kostron and T. Hasan, The Royal Society of Chemistry, 2016, pp. 591-599.
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Photo-produced singlet oxygen may be deactivated through the production of secondary reactive oxygen species (ROS). The lifespan, nature and the effects of these ROS depend on the local biochemical conditions such as tissue resistance to ROS. Using an in vitro assay involving Rose Bengal as a photosensitizer (1O2 quantum yield of 0.75), we noted that patients showed decreased systemic resistance to 1O2 during ischemic strokes (1O2 quantum yield of 1.83) or silent aneurysms (1O2 quantum yield of 1.15) and increased systemic resistance after subarachnoid hemorrhages (1O2 quantum yield of 0.65) (n = 20 for each) as compared to controls (1O2 quantum yield of 0.9 ± 10%). An inverse correlation (R2 = 0.98) was found with the vitamin D content of serum. This suggests that systemic oxidative changes are induced early during cerebral suffering, but differently according to the cause of brain tissue necrosis.