Excessive ultraviolet B (UVB) irradiation causes apoptotic cell death or induction of tumors in skin. Melatonin is a promising antioxidant and direct radical scavenger. Recently, it was reported that melatonin increases the survival of ultraviolet-B (UVB)-irradiated HaCaT keratinocyte cell lines. However, the precise molecular mechanisms underlying protective effect of melatonin on UVB damage a...

Epidermal keratinocytes overgrow in response to ultraviolet-B (UVB), which may be associated with skin photoaging and cancer development. Recently, we found that HIF-1alpha controls the keratinocyte cell cycle and thereby contributes to epidermal homeostasis. A further study demonstrated that HIF-1alpha is down-regulated by UVB and that this process is involved in UVB-induced skin hyperplasia. ...

Solar ultraviolet radiation (UVR) can reduce the photosynthesis and growth of benthic diatom communities in shallow freshwater. Nevertheless, greater amounts of algae accumulate in UVR-exposed habitats than in UVR-protected environments. Near-ultraviolet (UVA wavelengths of 320 to 400 nanometers) and mid-ultraviolet (UVB, wavelengths of 280 to 320 nanometers) radiation also inhibit algal consum...

Habitat use by animals often reflects the balance between conflicting demands such as foraging and avoiding predation. Environmental stressors such as temperature can also affect habitat use in many organisms, particularly in ectothermic animals. For example, warm, shallow thermal regimes in ponds can optimize growth and developmental rate of amphibian larvae but may also expose larvae to poten...

Environmental exposure to UVB (290-320 nm) wavelengths of the solar spectrum causes major damage, including carcinogenesis, in the skin. Therefore, cellular responses that protect against UVB damage are of particular interest in cutaneous epithelial cells. In cultured keratinocytes, mild hyperthermia generates a classical stress response with acquired thermotolerance and elevated stress protein...

Sunlight-induced non-melanoma skin cancer is the most prevalent cancer in the United States with more than two million cases per year. Several studies have shown an inhibitory effect of caffeine administration on UVB-induced skin cancer in mice, and these studies are paralleled by epidemiology studies that indicate an inhibitory effect of coffee drinking on non-melanoma skin cancer in humans. S...

Ultraviolet (UV) B causes oxidative stress, which has been implicated in carcinogenesis. We determined if the sensitivity of keratinocytes to UVB-induced oxidative stress is dependent on their differentiation state. In primary cultures of undifferentiated and differentiated mouse keratinocytes, UVB (25 mJ/cm(2)) stimulated production of reactive oxygen intermediates. This was associated with in...

Green tea polyphenols (GTPs) show promise as anticarcinogenic agents and may prevent the development of solar UV radiation–induced skin cancer. Here we investigated the mechanisms by which GTPs prevent UVB-induced skin cancer in mice. Two groups of 6to 7-wk-old female SKH-1 hairless mice were UVB irradiated (180 mJ/cm) 3 times each week for 24 wk. One group consumed water and the other, water c...

Ultraviolet radiation is the major environmental harmful factor that has emotional impact on human skin. The aim of the present study was to determine the mechanism of protection of cyanidin-3-O-glucoside against ultraviolet B (UVB)-induced damage to human HaCaT keratinocytes. Our results show that cyanidin-3-O-glucoside decreased the levels of intracellular reactive oxygen species generated by...

We examined the role of UVR (UV radiation) (UVA, 320-400 nm; UVB, 290-320 nm; and the combination of UVA and UVB) as a promoter in the induction of cutaneous melanoma. One hundred and seventy hairless mice (Skh-hr2), 6-8 weeks old, were treated in 8 groups: group I, DMBA [7,12-dimethylbenz(a)anthracene] plus UVA; group II, DMBA plus UVA plus UVB; group III, DMBA plus UVB; group IV, DMBA; group ...