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At least 505 records · Page 28Linked to original sources
PubMed1994

Sunlight: a major factor associated with the development of melanocytic nevi in Australian schoolchildren.

BACKGROUND: Case-control studies have identified melanocytic nevi (MN) as the most important phenotypic risk factor for melanoma. A knowledge of any environmental factors that cause MN may facilitate prevention of melanoma. OBJECTIVE: This study was undertaken to explore the possible role of ambient solar irradiation in the development of MN in children. METHODS: With a standard protocol developed after international consultation, the same medical observers examined children in three Australian cities (Melbourne, Sydney, and Townsville) that span a wide range of latitude. RESULTS: A total of 1123 Australian schoolchildren 6, 9, 12, and 15 years of age were surveyed. Larger numbers of MN were found (mean 65.4 MN, standard deviation 52.9) than in previous studies of children. Prevalence increased with diminishing latitude (51.1 in Melbourne, 66.5 in Sydney and 77.2 in Townsville), particularly in children 6 and 9 years of age. Although nevus numbers were higher in children with light skin and hair, blue eyes, and freckling, the latitude gradient remained after adjustment for these and other factors in multivariate analysis. CONCLUSION: Latitude of residence, and by implication ambient UV radiation, is strongly related to nevus prevalence in young Australian children. However, these differences diminish with age and may disappear by 15 years of age.

Adolescent↗
PubMed2002

Simulated sunlight-induced photodegradations of triasulfuron and cinosulfuron in aqueous solutions.

To elucidate the photochemical behavior of two sulfonylureas (cinosulfuron and triasulfuron) for which the chemical formulas are relatively close, their photodegradation was studied in water. All experiments were carried out under laboratory conditions using a xenon arc lamp as the source of radiation to simulate environmental conditions. Polychromatic quantum efficiencies were calculated to determine the photochemical pesticide lifetimes at pH 7, and a comparison with hydrolysis lifetimes has been performed. The results obtained showed clearly that at pH 7, photodegradation becomes a more important pathway than chemical degradation. HPLC-DAD was used to study the kinetics for both sulfonylureas and their photoproducts, whereas HPLC-MS (ESI in positive and negative modes) was used to identify photoproducts. These results suggest that the photodegradation of these two sulfonylureas proceeds via a number of reaction pathways: (1) cleavage of the sulfonylurea bridge; (2) desulfonylation, which can proceed either by a carbon-sulfur cleavage or a nitrogen-sulfur cleavage; (3) O-demethylation of methoxy moieties present on the triazine ring; and (4) O-dealkylation of benzene derivatives. In addition, it was found that the desulfonylation represented the main step and that it was wavelength dependent.

Chromatography, High Pressure Liquid↗
PubMed2004

Vitamin D3 from sunlight may improve the prognosis of breast-, colon- and prostate cancer (Norway).

OBJECTIVE: To investigate whether prognosis of breast-, colon- and prostate cancer may be related to vitamin D(3), induced from solar ultra-violet (UV) radiation, through studies on geographical and seasonal variations in UV radiation. METHODS: This study includes 115,096 cases of breast-, colon- or prostate cancer, diagnosed between 1964 and 1992. Among these, 45,667 deaths due to the cancer were registered. On the basis of a north-south gradient in solar UV radiation and geographical climatic differences, Norway was divided into eight residential regions. According to seasonal variations in UV radiation, four periods of diagnosis during the year were used. Case fatality according to residential region and to season of diagnosis was estimated using Cox regression. The effects of occupational sun exposure, childbearing pattern and educational level were also evaluated. RESULTS: No geographic variation in case fatality was observed for the three cancer types studied. A significant variation in prognosis by season of diagnosis was observed. Diagnoses during summer and fall, the seasons with the highest level of vitamin D(3), revealed the lowest risk of cancer death. CONCLUSION: The results suggest that a high level of vitamin D(3) at the time of diagnosis, and thus, during cancer treatment, may improve prognosis of the three cancer types studied.

Breast Neoplasms↗