Residual photosensitizer

Vilaplana J, Romaguera C, Azon A, Lecha M. Flutamide photosensitivity—residual vitiliginous lesions. Contact Dermatitis 1998 38(2) 68-70. 

Figure 1.2 Modified nucleotides and nucleosides described in the text. (A) Nucleotides incorporated by polymerases yielding nuclease-resistant oligonucleotides. Top from left to right 2 -fluoro, 2 -amino, 2 -0-methyl. Bottom from left to right boranophosphate, phosphorothioate, 4 -thio. (B) Photosensitive residues. Left to right 5-bromo-U, 2-(2-nitrophenyl)ethyl T, 2-(2-nitrophenyl)propyl T. (C) Amino-imino equilibrium used in 2D-SELEX (see the text).

In a considerable number of cases, peptidyl-tRNA affinity probes were shown to modify primarily not the ribosomal proteins, but the 23 S rRNA. Further characterization of modified sites was obtained by splitting of the 23 S rRNA into 13 S and 18 S fragments including the 5 third and the 3 two-thirds of the molecule, respectively. Mapping of tRNA Binding Sites. Identification of ribosomal components interacting with parts of tRNA other than the 3 end has been attempted by preparing tRNAs derivatized in odd bases with photosensitive residues. Affinity probes are listed in Table III. Assays for func-... 

It is likely that cross-linking of an organic copolymer proceeds through a stage of excitation and photochemical conversion of photosensitive side-chain organotin fragments containing coordination-bound residues. 

Tetrahydrofuran has been reported to exhibit an absorption maximum at 280 nm (52,56), but several workers have shown that this band is not produced by the purified solvent (30,41,57). Oxidation products from THF have been invoked in order to account for the appearance of the 280-nm band in PVC films that are solvent-cast from THF in air (57. 581. However, in some reported cases (56,59), this band was undoubtedly produced, at least in part, by a phenolic antioxidant (2.6-di-tert-butyl-p-cresol)(59) in the solvent. Since certain -alkylphenols have now been shown to be powerful photosensitizers for the dehydrochlorination of PVC (60), it is clear that antioxidant photosensitization might well have been responsible for some of the effects attributed previously (56) to THF alone. On the other hand, enhanced rates of photodegradation under air have also been observed for PVC films cast from purified THF (57), a result which has been ascribed to radical formation during the photooxidation of residual solvent (57,61). Rabek et al. (61) have shown that this photooxidation produces a-HOO-THF, a-HO-THF, and y-butyro-lactone, and they have found that the hydroperoxide product is an effective sensitizer for the photodehydrochlorination of PVC at X = 254 nm (61). 

Foster So there is some residual photosensitivity in the triple knockout. Do you ascribe this to residual cones or to the novel opsin ... 

Azelaic acid is a newer treatment for hyperpigmentation, primarily for post-inflammatory hyperpigmentation. It works by blocking the activity of tyrosinase and does not cause photosensitivity of the skin or residual changes in the skin. There is decreased incidence of allergic reactions associated with azelaic acid. Corticosteroids also block the activity of tyrosinase. Corticosteroids are used in combination with other drugs to minimize the side effects. The combination of azelaic acid and hydrocortisone acetate (10%) may also be useful in the treatment of post-inflammatory hyperpigmentation of skin... 

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