BACKGROUND Photodegradation of certain vitamins such as riboflavins, carotinoids, tocopherol, and folate has been well-documented. Previous observations suggest that ultraviolet (UV) radiation may cause folate deficiency. This is of great importance since folate deficiency is also known to be linked with the development of neural tube defects. To investigate the influence of UVA radiation on se...

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 ...

The photochemical aminomethyltrimethyl psoralen (AMT), in conjunction with UV A light (UVA), has been shown to inactivate human immunodeficiency virus-1 and model viruses in platelet suspensions under conditions that have only a minimal effect on in vitro platelet properties. A rabbit ear bleeding time technique was used to assess the hemostatic effectiveness of human platelet suspensions treat...

PURPOSE To evaluate the role of corneal epithelium in riboflavin/ultraviolet-A (UVA) mediated corneal collagen cross-linking treatment. METHODS Fifty New Zealand rabbits were divided into 5 groups: UVA treatment with or without corneal epithelium, UVA+riboflavin treatment with or without corneal epithelium, and control without any treatment. All rabbits were sacrificed after irradiation and s...

Deleterious effects of UV radiation in tissue are usually attributed to different mechanisms. Absorption of UVB radiation in cell constituents like DNA causes photochemical reactions. Absorption of UVA radiation in endogenous photosensitizers like vitamins generates singlet oxygen via photosensitized reactions. We investigated two further mechanisms that might be involved in UV mediated cell ti...

UVA contributes to the pathogenesis of skin aging by downregulation of procollagen I content and induction of matrix metalloproteinase (MMP)-associated responses. Application of antioxidants such as lycopene has been demonstrated as a convenient way to achieve protection against skin aging. Lycogen™, derived from the extracts of Rhodobacter sphaeroides, exerts several biological effects similar...

Ultraviolet A (UVA) irradiation is responsible for a variety of changes in cell biology. The purpose of this study was to investigate effects of aspartic acid on UVA irradiation-induced damages in the stemness properties of human adipose tissue-derived mesenchymal stem cells (hAMSCs). Furthermore, we elucidated the UVA-antagonizing mechanisms of aspartic acid. The results of this study showed t...

Long wavelength ultraviolet radiation (UVA, 320-400 nm) interacts with chromophores present in human cells to induce reactive oxygen species (ROS) that damage both DNA and proteins. ROS levels are amplified, and the damaging effects of UVA are exacerbated if the cells are irradiated in the presence of UVA photosensitizers such as 6-thioguanine (6-TG), a strong UVA chromophore that is extensivel...

The therapeutic thiopurines, including the immunosuppressant azathioprine (Aza) cause the accumulation of the UVA photosensitizer 6-thioguanine (6-TG) in the DNA of the patients' cells. DNA 6-TG and UVA are synergistically cytotoxic and their interaction causes oxidative damage. The MUTYH DNA glycosylase participates in the base excision repair of oxidized DNA bases. Using Mutyh-nullmouse fibro...

Gap junction intercellular communication (GJIC) is essential for the proper function of many organs including the lens. Disruption of GJIC can cause lens metabolic disorder and can induce cataracts. The purpose of this study was to investigate the signal transduction pathways involved in GJIC disruption following ultraviolet A (UVA) exposure in lens epithelial cells. Following exposure of human...