UV-A radiation (wavelength 320–400 nm) reaches more deeply into the skin and can lead to the generation of reactive oxygen species, which in turn can damage cell membranes, signaling proteins, and nucleic acids. UV-B radiation (wavelength 290–320 nm) causes thymidine dimer formation in DNA and RNA, leading to significant cellular mutations. In particular, mutations in the p53 tumor suppressor gene have been found in 30–50% of AK lesion skin samples.UV radiation has also been shown to cause elevated inflammatory markers such as arachidonic acid, as well as other molecules associated with inflammation. Eventually, over time these changes lead to the formation of AKs. Several predictors for increased AK risk from UV radiation have been identified:

Extent of sun exposure: Cumulative sun exposure leads to an increased risk for development of AKs. In one U.S. study, AKs were found in 55% of fair-skinned men with high cumulative sun exposure, and in only 19% of fair-skinned men with low cumulative sun exposure in an age-matched cohort (the percents for women in this same study were 37% and 12% respectively). Furthermore, the use of sunscreen (SPF 17 or higher) has been found to significantly reduce the development of AK lesions, and also promotes the regression of existing lesions. History of sunburn: Studies show that even a single episode of painful sunburn as a child can increase an individuals risk of developing AK as an adult. Six or more painful sunburns over the course of a lifetime was found to be significantly associated with the likelihood of developing AK.
The treatment was considered successful if the participant maintained low-levels (less than 50 copies/mL) of HIV RNA in their blood for at least 48 weeks. In these studies, 91% of subjects with HIV-1 who took the dolutegravir/lamivudine combination no longer had detectable levels of HIV (i.e. they had fewer than 50 copies per ml) after 48 weeks compared with 93% of those who were taking the triple combination. In neither study was there a case of resistance to treatment after 48 weeks. References
External links
"Dolutegravir". Drug Information Portal. U.S. National Library of Medicine. "Lamivudine". Drug Information Portal. U.S. National Library of Medicine.