Photosensitive systems, retinoids

Tetracyclines inhibit P. acnes, reduce the amount of keratin in sebaceous follicles, and have antiinflammatory properties (inhibiting chemotaxis, phagocytosis, complement activation, and cell-mediated immunity). Drawbacks to tetracyclines include hepatotoxicity and predisposition to infections (e.g., vaginal candidiasis). Other adverse effects include GI disturbances, photosensitivity, tooth discoloration in children, and inhibition of skeletal growth in the developing fetus. Tetracyclines must not be combined with systemic retinoids because of an increased risk of intracranial hypertension. / Tetracycline is the least expensive agent in this class and is often... 

Bleaching of rhodopsin in bovine retina. Absorption of light by 11-cii-retinaldehyde initiates the configurational change to a -trans retinaldehyde, culminating in hydrolysis of the bond between retinaldehyde and Lys 53 of opsin. The order of formation of the intermediates is tentative. The symbol hv represents a photon of visible light. [Modified and reproduced, with permission, from C. D. B. Bridges, Retinoids in photosensitive systems. In The Retinoids, Vol. 2,... 

JC Saari. Retinoids in photosensitive systems. In MB Sporn, AB Roberts, DS Goodman, eds. The Retinoids. New York Raven Press, 1994, pp 351-385. 

The biosynthesis and regeneration of these photosensitive pigments requires that retinaldehyde (or a retinoid precursor) is provided to the membranes in which they are sequestered. The delivery of retinoids to these membranes, which are generally found in specialized photoreceptor cells, has been investigated in some vertebrates. In these animals, proteins called retinoid-binding proteins serve as vehicles that transport retinoids in the serum, cell sap, and interstitial space of the eye. The critical role of these proteins in the normal functioning of the vertebrate visual system is one of the major topics of this chapter. 

Treatment of cutaneous T-cell lymphoma can be topical skin-directed or systemic. Topical options are used in the early skin-localized stage of the disease and include emollients, steroids, UVB radiation, retinoids, and PUVA. PUVA can produce relatively long-lived remissions. However, it is also associated with short-term side effects of oral psoralen intake, including nausea, vomiting, inconsistent gastrointestinal absorption, and long-term complications such as photosensitivity and the potential for development of skin cancer... 

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