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It has been reported that UV radiation leads to local and systemic immunosuppression, due to DNA damage and altered cytokine expression. This has implications in cutaneous tumor surveillance. The Langerhans cells may undergo changes in quantity, morphology, and function due to UV exposure and may eventually become depleted. One proposed ...
Radiation hormesis is the conjecture that a low level of ionizing radiation (i.e., near the level of Earth's natural background radiation) helps "immunize" cells against DNA damage from other causes (such as free radicals or larger doses of ionizing radiation), and decreases the risk of cancer. The theory proposes that such low levels activate ...
According to the National Toxicology Program Report on Carcinogens from the US Department of Health and Human Services, broad-spectrum UV radiation is a carcinogen whose DNA damage is thought to contribute to most of the estimated 1.5 million skin cancers and the 8,000 deaths due to metastatic melanoma that occur annually in the United States.
DNA absorption of UV radiation can also lead to TC, CC, and TT lesions but with much less frequency. The failure of DNA repair mechanisms to fix such lesions notably characterizes photocarcinogenesis. [2] In addition, UV radiation often increases the production of cytokines such as interleukin-10 which indirectly hinder antigen presentation in ...
One of the largest promoters of apoptosis is exposure to ultraviolet (UV) light. While UV light is essential to human life it can also cause harm by inducing cancer, immunosuppression, photoaging, inflammation, and cell death. [1] Of the various components of sunlight, ultraviolet radiation B (UVB) (290-320 nm) is considered to be the most harmful.
This process of absorption works to reduce the risk of DNA damage and the formation of pyrimidine dimers. UVA light makes up 95% of the UV light that reaches earth, whereas UVB light makes up only about 5%. UVB light is the form of UV light that is responsible for tanning and burning. Sunscreens work to protect from both UVA and UVB rays.
All bands of UV radiation damage collagen fibers and accelerate aging of the skin. Both UVA and UVB destroy vitamin A in skin, which may cause further damage. [67] UVB radiation can cause direct DNA damage. [68] This cancer connection is one reason for concern about ozone depletion and the ozone hole.
DNA photoionization is the phenomenon according to which ultraviolet radiation absorbed directly by a DNA system (mononucleotide, single or double strand, G-quadruplex…) induces the ejection of electrons, leaving electron holes on the nucleic acid. The loss of an electron gives rise to a radical cation on the DNA.