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UVA light makes up the majority of incident solar radiation throughout the year. Although it penetrates deeply into the skin, it does not cause sunburn, nor does it damage DNA directly. The metabolism of thiopurines results in the incorporation of 6-thioguanine (6-TG) into the DNA of skin, and patients treated with thiopurines have a reduced minimal erythema dose for UVA, but not UVB light.18 Unlike the canonical DNA bases, which do not absorb UVA light to a significant degree, DNA 6-TG is a strong UVA chromophore. Photochemical activation of DNA 6-TG by UVA light triggers DNA and protein oxidation resulting in DNA breakage, DNA crosslinking, oxidation of DNA bases and the covalent attachment of proteins to DNA.19 An active DNA mismatch repair system and further modification of DNA 6-TG are also required for cytotoxicity, so that when dividing cells are exposed to low levels of UVA radiation, see more the 6-TG metabolite is converted into reactive oxygen species and guanine-6-sulfonate (which is also mutagenic). The

resultant oxidative stress also produces DNA lesions16,18 and the potential to develop skin cancers. selleck kinase inhibitor The work by Shetsedi and colleagues14 adds to the literature in allowing us to counsel people regarding thiopurines and risk of skin cancer. Thiopurines have an additive effect in increasing the risk of NMSC in those with previous ultraviolet exposure. Childhood is an important period for potential UV exposure, and sun care precautions should be promoted universally in childhood, particularly in those with light skin types, as should protective clothing and head-gear as has become customary (mandated) in primary school settings in Australia. If

IBD patients who have had significant previous sun exposure need to be on thiopurines, appropriate advice may include the use of UV-radiation protection (e.g. clothing, sunscreen) before going outdoors and regular dermatological review. Patients should also be advised about the risk of developing vitamin D deficiency and monitored accordingly.17 “
“In Asia, the prevalence 上海皓元医药股份有限公司 of Helicobacter pylori (H. pylori) infection varies markedly in different countries. Higher prevalence rates are found in developing Asian countries while lower rates have been reported in more industrialized and developed countries. Within a country, the seroprevalence rates may vary between distinct geographic regions. H. pylori infection is an important etiological factor for the occurrence of non-cardia gastric adenocarcinoma. The incidence rate of gastric adenocarcinoma in Asia tends to mirror the seroprevalence rate of H. pylori infection; however, there are populations with high seroprevalence rates of H. pylori infection that paradoxically have low incidence rates of gastric adenocarcinoma.