Photo-oxidation of N'-formylkynurenine and tryptophan peptides by sunlight or simulated sunlight.
Explore the source record for details and available documents.
Formates↗
SEARCH · PubMed Health
Results for “SUNLIGHT”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Sunlight and health. Not all sunlight is dangerous, just ultraviolet radiation.
Explore the source record for details and available documents.
Humans↗
Sunlight and health. Exposure to sunlight may reduce cancer risk.
Explore the source record for details and available documents.
Breast Neoplasms↗
[Sunlight effects, sunlight dermatosis and sunburn prevention].
Explore the source record for details and available documents.
Humans↗
Can sunlight replace phototherapy units in the treatment of neonatal jaundice? An in vitro study.
BACKGROUND/AIM: Light can be efficiently used for the treatment of neonatal jaundice. Sunlight, which covers a large portion of the light spectrum including the bilirubin-absorbing range, is abundant in the Middle East. Such advantages prompted the present study to investigate the efficiency of sunlight in isomerizing bilirubin. This may introduce a practical source of light for the treatment of hyperbilirubinic infants in areas where phototherapy units are not available. METHODS: The efficiency of sunlight was quantified by a comparison with a phototherapy unit. Aqueous bilirubin solutions were exposed to periodic sunlight over the entire year and the reduction of bilirubin concentration was monitored spectrophotometrically. Bilirubin solutions were also exposed to a phototherapy unit intensity comparable to that of sunlight (17 cm away from the source). RESULTS: The data indicated that at this comparable light intensity, the phototherapy unit was as effective as sunlight. However, for the treatment of neonatal jaundice, phototherapy units are usually operated at a distance of 50 cm (where the light intensity is six times less than that of sunlight). When this distance was tested, only 16% of bilirubin was isomerized in the first 5 min of exposure. In contrast, about 65% of bilirubin was isomerized when the phototherapy unit was placed at a distance of 17 cm and when the bilirubin solutions were exposed to sunlight for the same time period. The hourly and seasonal changes in sunlight intensity affected the reduction in bilirubin concentration significantly. CONCLUSION: Data revealed that sunlight is almost 6.5 times more effective than a phototherapy unit when operating at the ward geometry after taking isomerization efficiency and area of exposure into consideration. Moreover, sunlight is still more effective during the winter season, when its intensity is lower. Thus, sunlight may be considered an alternative phototherapy source for the treatment of neonatal jaundice, particularly in areas where conventional phototherapy units are unavailable.
Bilirubin↗
Residential and occupational exposure to sunlight and mortality from non-Hodgkin's lymphoma: composite (threefold) case-control study.
OBJECTIVE: To determine whether non-Hodgkin's lymphoma mortality is associated with sunlight exposure. DESIGN: Three case-control studies based on death certificates of non-Hodgkin's lymphoma, melanoma, and skin cancer mortality examining associations with potential sunlight exposure from residence and occupation. SETTING: 24 states in the United States. SUBJECTS: All cases were deaths from non-Hodgkin's lymphoma, melanoma, and non-melanotic skin cancer between 1984 and 1991. Two age, sex, and race frequency matched controls per case were selected from non-cancer deaths. MAIN OUTCOME MEASURES: Odds ratios for non-Hodgkin's lymphoma, melanoma, and skin cancer from residential and occupational sunlight exposure adjusted for age, sex, race, socioeconomic status, and farming occupation. RESULTS: Non-Hodgkin's lymphoma mortality was not positively associated with sunlight exposure based on residence. Both melanoma and skin cancer were positively associated with residential sunlight exposure. Adjusted odds ratios for residing in states with the highest sunlight exposure were 0.83 (95% confidence interval 0.81 to 0.86) for non-Hodgkin's lymphoma, 1.12 (1.06 to 1.19) for melanoma, and 1.30 (1.18 to 1.43) for skin cancer. In addition, non-Hodgkin's lymphoma mortality was not positively associated with occupational sunlight exposure (odds ratio 0.88; 0.81 to 0.96). Skin cancer was slightly positively associated with occupational sunlight exposure (1.14; 0.96 to 1.36). CONCLUSIONS: Unlike skin cancer and to some extent melanoma, non-Hodgkin's lymphoma mortality was not positively associated with exposure to sunlight. The findings do not therefore support the hypothesis that sunlight exposure contributes to the rising rates of non-Hodgkin's lymphoma.
Adult↗
Sunlight and mortality from breast, ovarian, colon, prostate, and non-melanoma skin cancer: a composite death certificate based case-control study.
OBJECTIVES: To explore whether mortality from female breast, ovarian, colon, and prostate cancer were negatively associated with exposure to sunlight. METHODS: A death certificate based case-control study of mortality was conducted into five cancers: female breast, ovarian, colon, prostate, and non-melanoma skin cancer (as a positive control) to examine associations with residential and occupational exposure to sunlight. Cases were all deaths from these cancers between 1984 and 1995 in 24 states of the United States. Controls, which were age frequency matched to a series of cases, excluded deaths from cancer and certain neurological diseases. Multiple logistic regression was used in a model that included age, sex, race, residential exposure to sunlight (based on region), and socioeconomic status, occupational exposure to sunlight, and physical activity (the last three based on usual occupation). RESULTS: Residential exposure to sunlight was negatively and significantly associated with mortality from female breast, ovarian, prostate, and colon cancer. Only female breast and colon cancer, however, also showed significant negative associations with jobs with the highest occupational exposure to sunlight (odds ratio (OR) 0.82 (95% confidence interval (95% CI) 0.70 to 0.97) for female breast cancer; OR 0.90 (95% CI 0.86 to 0.94) for colon cancer). For both cancers, the negative association with occupational sunlight was greatest in the geographical region of highest exposure to sunlight and was independent of physical activity on the job. Non-melanoma skin cancer, as expected, was positively associated with both residential and occupational sunlight. CONCLUSIONS: In this exploratory study, unlike mortality from non-melanoma skin cancer, mortality from female breast cancer and colon cancer were negatively associated with both residential and occupational sunlight.
Adult↗
Amelioration of osteoporosis and hypovitaminosis D by sunlight exposure in stroke patients.
BACKGROUND: The authors' previous investigations have disclosed low serum 25-hydroxyvitamin D (25-OHD) concentrations in 45 patients during long-term hospitalization following stroke (mean 5.9 ng/mL). This 25-OHD deficiency resulted from sunlight deprivation. OBJECTIVE: To evaluate the efficacy of sunlight exposure in increasing serum 25-OHD, in reducing the severity of osteoporosis in bone mineral density (BMD), and in decreasing the risk of hip fractures in chronically hospitalized, disabled stroke patients. METHODS: In a 12-month randomized and prospective study of stroke patients, 129 received regular sunlight exposure for 12 months, and the remaining 129 (sunlight-deprived) did not. RESULTS: At baseline, patients of both groups showed vitamin D deficiency. BMD increased by 3.1% in the sunlight-exposed group and decreased by 3.3% in the sunlight-deprived group (p = 0.0001). 25-OHD level increased by fourfold in the sunlight-exposed group. Six patients sustained hip fractures on the hemiplegic side in the sunlight-deprived group, and one hip fracture occurred among the sunlight-exposed group (p = 0421; odds ratio = 6.1). CONCLUSION: Sunlight exposure can increase the BMD of vitamin D-deficient bone by increasing 25-OHD concentration.
Aged↗
Leisure time, sunlight exposure and cataracts.
Leisure time sunlight exposure is a small or insignificant portion of total sunlight exposure experienced by most people at high risk for cataract. Few studies have been undertaken to evaluate a possible causal relationship, and these have largely been in Western countries. Analyses of data from the National Health and Nutrition Examination Survey (1971-1972) failed to confirm a relationship between leisure time exposure and cataract, but suggested that total exposure to sunlight was significantly related to cataract. A case-control study of cataract in Iowa suggested that controls were more likely to have shielded their eyes from sunlight than cases. A study in Italy suggested a positive relationship between leisure time sunlight exposure and lens opacities. In the large population-based Beaver Dam Eye Study population, we evaluated estimates of sunlight exposure and cataracts. We did not find that more leisure time sunlight exposure was associated with lens opacities. However, in men, estimates of lifetime exposure to ultraviolet-B were associated with cortical cataract. In summary, there is evidence to suggest that sunlight exposure may be related to cataract in diverse populations. Leisure time sunlight exposure is probably responsible for a small portion of that exposure.
Adult↗
Effect of sunlight on enumeration of indicator bacteria under field conditions.
The effect of sunlight on the enumeration of fecal coliform (FC) and fecal streptococcal (FS) bacteria when water samples are collected in containers and brought back to the laboratory for analysis or when the water samples are filtered through membranes on site was determined. FC and FS in raw sewage stored in clear glass or translucent polyethylene containers were resistant to the effects of sunlight. However, under the same conditions of storage and exposure to sunlight, 90% of FC and FS in sewage diluted 1:100 in seawater were inactivated within 13 to 32 min. When sewage was similarly diluted in stream water and exposed to sunlight, 90% of FC were inactivated after 28 to 38 min, whereas 90% of FS were not inactivated even after a 2-h exposure to sunlight. Other experiments showed that 90 to 99% of FC and FS retained on membranes were inactivated when these membranes were exposed to sunlight for 10 to 15 min. FS were inherently more resistant to sunlight inactivation than were FC. Finally, evidence was obtained to show that sunlight initially stresses the bacteria but eventually causes cell death.
Bacteria↗
Association of sunlight exposure and photoprotection measures with clinical outcome in systemic lupus erythematosus.
This study was designed to explore the relationship of sunlight exposure and ultraviolet (UV) light protection measures with clinical outcome in systemic lupus erythematosus (SLE). A structured questionnaire was administered to sixty Puerto Rican SLE patients, to assess their attitudes and behavior regarding sunlight exposure and photoprotection measures. Medical records were reviewed to evaluate the clinical outcome measures that included: clinical manifestations, number of SLE-related hospitalizations, number of exacerbations and pharmacologic treatment. Almost all (98.3%) patients were well acquainted of sunlight effects on disease activity. Two thirds were exposed to direct sunlight for an average of less than one hour per day and 33.3% for one hour or more. Thirty patients (50%) reported use of sunscreen, with sun protective factor of 15 or greater, when exposed to sunlight. Less than 40% of patients regularly wore hat or long-sleeves clothes to protect from sunlight. Although there were some clinical differences between the groups with different sunlight exposure times, none reached statistical significance. Also, no significant differences were found between the groups in regards to sunlight protective clothes. However, patients that regularly used sunscreen had significantly lower renal involvement (13.3 vs 43.3%), thrombocytopenia (13.3 vs 40%), hospitalizations (26.7 vs. 76.7%), and requirement of cyclophosphamide treatment (6.7 vs. 30%) than patients that did not used it (P < 0.05). We conclude that use of sunscreen photoprotection was associated with a better clinical outcome in our SLE patients. These findings further support the importance and benefits of photoprotective measures in patients with SLE.
Adult↗
Increased polycyclic aromatic hydrocarbon toxicity following their photomodification in natural sunlight: impacts on the duckweed Lemna gibba L. G-3.
The authors previously demonstrated that simulated solar radiation (SSR), with a fluence rate of only 40 mumol m-2 sec-1, increased polycyclic aromatic hydrocarbon (PAH) toxicity to the duckweed Lemna gibba and that PAHs photomodified in SSR (generally oxygenation of the ring system) are more toxic than the parent compounds (Huang et al., Environ. Toxicol. Chem., 1993, 12, 1067-1077). It is not known, however, to what extent toxicity of PAHs can increase due to photomodification. Thus, natural sunlight, which has a high fluence rate (approximately 2000 mumol m-2 sec-1), was used to photomodify anthracene, benzo[a]pyrene, fluoranthene, phenanthrene, and pyrene. Toxicity was based on growth inhibition of L. gibba, measured as the rate of production of new leaves over an 8-day period. Initially, the toxicity of the PAHs applied in intact form was probed, with the compounds demonstrating greater toxicity in sunlight than in SSR. Next the PAHs were photomodified in sunlight prior to incubation with the plants. The half-lives of the PAHs in sunlight ranged from 12 min to 30 hr. Although most of the products of PAH photomodification are not yet identified, the degree that PAH toxicity increased following photomodification in sunlight could still be probed. The mixtures of photomodified chemicals that were derived from each PAH in sunlight were applied of L. gibba and growth inhibition under 100 mumol m-2 sec-1 of SSR was determined. The LC50s for the PAH photoproducts generated in sunlight were an order of magnitude lower than the LC50s for the PAHs applied in intact form.
Anthracenes↗
Sunlight mutagenesis: changes in mutational specificity during the irradiation of phage M13mp2.
We reported previously that the mutations in phage M13mp2, a single-stranded DNA phage, induced by sunlight exposure are predominated by G-to-C transversions. We have now made an unexpected observation that an exposure to sunlight for a short period of time results in induction mainly of C-to-T transitions while a longer exposure results in the induction of G-to-C transversions. This peculiar phenomenon suggests that DNA damage formed by initial sunlight exposure can be transformed during an elongated exposure. 7, 8-Dihydro-8-oxoguanine (8-oxoG) in DNA might be involved in the shift of the mutational specificity, as 8-oxoG was formed in the phage DNA upon the sunlight exposure. We also compared the mutagenic activity of UVB irradiation with that of sunlight exposure. The results demonstrate that the genotoxic properties of sunlight and UVB in phage M13mp2 mutagenesis are different. The shift in the mutational specificity associated with the dose of the sunlight may call for general cautions in the studies of agent-induced mutagenesis.
Bacteriophage M13↗
Sunlight and iron(III)-induced photochemical production of dissolved gaseous mercury in freshwater.
Mechanistic understanding of sunlight-induced natural processes for production of dissolved gaseous mercury (DGM) in freshwaters has remained limited, and few direct field tests of the mechanistic hypotheses are available. We exposed ferric iron salt-spiked fresh surface lake water (Whitefish Bay, Lake Superior, MI) in Teflon bottles and pond water (Oak Ridge, TN) in quartz bottles to sunlight in the field to infer if sunlight and Fe(III)-induced photochemical production of DGM could mechanistically contribute partly to natural photochemical production of DGM in freshwaters. We found that exposure of freshwater spiked with fresh Fe(III) (approximately 5 or 10 microM) to sunlight led to repeatable, significantly larger increases in DGM production (e.g., 380% in 1 h, 420% in 2 h, and 470% in 4 h for Whitefish Bay water) than exposure without the spike (e.g., 200% in 6 h). DGM increased with increasing exposure time and then often appeared to approach a steady state in the tests. Higher Fe(III) spike levels resulted in the same, or even less, DGM production. Storage of the water with or without Fe(III) spike in the dark after sunlight exposure led to significant, apparently first-order, decreases in DGM. These phenomena were hypothetically attributed to sunlight-induced photochemical production of highly reducing organic free radicals through photolysis of Fe(III)-organic acid coordination compounds and subsequent reduction of Hg(II) to Hg(0) by the organic free radicals; the reduction was also accompanied by dark oxidation of Hg(0) by photochemically originated oxidants (e.g., .OH). This study suggests that sunlight and Fe(III)-induced photochemical reduction of Hg(II) could be one of the mechanisms responsible for natural photochemical production of DGM in freshwaters and that Fe species may be influential in mediating Hg chemodynamics and its subsequent toxicity in aquatic ecosystems.
Fresh Water↗
Effect of sunlight on survival of indicator bacteria in seawater.
The stability of the natural populations of fecal coliforms and fecal streptococci in raw sewage diluted 1:1,000 in seawater or phosphate-buffered water at 24 +/- 2 degrees C was markedly affected by the absence or presence of sunlight. In the absence of sunlight, these bacteria survived for days, whereas in the presence of sunlight 90% of the fecal coliforms and fecal streptococci were inactivated within 30 to 90 min and 60 to 180 min, respectively. The bactericidal effect of sunlight was shown to penetrate glass, translucent polyethylene, and at least 3.3 m of clear seawater, suggesting that the visible rather than the ultraviolet light spectrum of sunlight was primarily responsible for the observed bactericidal effect. However, these same sewage-borne bacteria were relatively resistant to the bactericidal effect of sunlight when diluted in fresh mountain stream waters. These results indicate that the presence of sunlight is a major factor controlling the survival of fecal coliforms and fecal streptococci in seawater.
Enterobacteriaceae↗
Sensitivity of Legionella pneumophila to sunlight in fresh and marine waters.
Studies were carried out to assess the sunlight sensitivity of Legionella pneumophila suspended in fresh and marine waters. Comparison studies on sunlight sensitivity of lake water bacteria, Pseudomonas aeruginosa, Escherichia coli and Streptococcus faecalis, were also undertaken. The effects of full sunlight and polyacrylic-screened sunlight were monitored in the study. Results indicate that L. pneumophila cells are slightly more sensitive to sunlight in seawater than in fresh water. Enumeration of sunlight-stressed bacteria in fresh water was found to be dependent on the medium used, and the following order of sensitivity to sunlight, from least to most sensitive, was noted: natural lake water bacteria, L. pneumophila, P. aeruginosa, E. coli, and S. faecalis.
Culture Media↗
[Effect of previous culture conditions and the presence of the rpoS gene on the survival of Salmonella typhimurium in sea water exposed to sunlight].
The effect of sunlight exposure on Salmonella typhimurium isogenic strains harboring an rpoS gene functional (rpoS+) or not functional (rpoS-) was investigated in microcosms of sterile sea water at 20 degrees C. The two strains rapidly lost their ability to produce colonies on solid culture media. The detrimental action of sunlight was more important when the salinity of sea water increased. The survival of stationary phase cells was influenced by RpoS. Bacteria grown in media with high salinity or osmolarity and transferred to sea water in stationary phase were more resistant to irradiation than those grown in media with low salinity. Prior growth under oxidative (0.2 mmol/L of H2O2) or amino acid starved (minimal medium) conditions did not modify the survival of either strain when they were exposed to sunlight. Bacteria were more resistant when cells were incubated in sea water in the dark prior to being exposed to sunlight. The resistance to sunlight irradiation was also greater in clones of both strains isolated from microcosms exposed to sunlight for 90 min, then further inoculated into sea water and reexposed to sunlight.
Adaptation, Physiological↗
Ocular risks from sunlight exposure.
Relinquishing the desire to acquire a tan will be difficult for many people. To many individuals, a tan is a symbol of health, fashion and attractiveness. Even when informed about the risks of sunlight exposure, many people ignore the advice to change their behaviors and decrease their risks. Adoption of safe sunlight precautions depends on individual preference, age, work requirements, gender, and perception of personal risk. Many people selectively adhere to certain protective behaviors which do not conflict with social norms. Reinforcement of how sunlight can damage the eyes and skin needs to be continually provided so that public attitudes can adapt to all the necessary appropriate behaviors. Ophthalmic health care professionals have an important part in public education. They can customize their patient's personal protective requirements to match the type of risks uncovered in the clinical work up. The ocular and social history should include the patient's sunlight exposure risk profile and document pre-existing sunlight damage to the eyes and facial areas. All follow-up visits should reinforce sunlight exposure information and document compliance or non-compliance. Only in this way can the eye care delivery system support preventative measures to decrease ocular injuries from sunlight radiation.
Environmental Exposure↗