ABSTRACT
Clinical and Histologial Investigations . . . . . . . . . . . . . . . . . . . . . . . . . . . .259 13.3. Effect of BGP-15M on Acute DNA Damage and ADP-Ribosylation in
UV-Exposed Skin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .260 13.4. Role of BGP-15M in UV-Induced Sunburn Cell Formation . . . . . . . . . . . .265 13.5. Effect of BGP-15M on UV-Induced Immune Suppression in the Skin . . .267 13.6. Effect of BGP-15M on Photocarcinogenesis in Hairless Mouse Skin . . . .267 13.7. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .270 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
The ultraviolet (UV) components of sunlight are now recognized as major environmental factors deleterious to human health.1-4 Skin cancer is the most common malignancy among Caucasians.2,4-8 The UV light in the solar spectrum is conventionally divided into UVC (200 to 290 nm; this does not reach the Earth), UVB (290 to 320 nm) and UVA, which is subdivided into short-wave UVA II (320 to 340 nm), and long-wave UVA I (340 to 400 nm). The UV rays of sunlight penetrate into the skin as a function of their wavelengths. Radiation of shorter wavelengths (UVB) is mostly absorbed in the epidermis and interacts predominantly with keratinocytes. Radiation of longer wavelengths (UVA, 320 to 400 nm) penetrates deeper, affecting the epidermal and dermal cells. Convolution of the spectra with biological damage
action spectra shows that, despite the significantly greater incidence of UVA radiation (95% of the UV reaching the Earth), the predominant acute and chronic damages to the skin are associated with the UVB portion of the solar spectrum (in a ratio of 4:1).9-11 However, the adverse effects of UVA and UVB are usually additive.11,12 Photodamage, specific damage produced in the skin tissue by single or repeated (cumulative) exposure to UV light (290 to 400 nm), is considered to be the initiating step of photocarcinogenesis.13 UV radiation-induced injury to the skin can be subdivided into acute (e.g., sunburn) and chronic (e.g., photoaging, solar keratosis, and skin cancers) photodamage.
