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PubMed1981

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↗
PubMed1984

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↗
PubMed2004

[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↗
PubMedDate not supplied

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↗
PubMed1984

Study of ultraviolet radiation and genotoxic effects of natural sunlight in relation to skin cancer in Saudi Arabia.

Sunlight-related biological effects such as skin cancer, sunburning, and synthesis of vitamin D in the body have been found to be very low in people in the midregion of Saudi Arabia. The present studies were undertaken to measure the sunburning-carcinogenic ultraviolet light (UV) radiation (UV-B) in natural sunlight in the city of Riyadh (25 degrees north latitude). The average noontime incidence of UV-B, measured with a sunburn UV-meter, was found to be between 1.9 and 3.4 sun units/hr in the months of March to May. Concomitantly with the UV measurements, a bioassay using a wild-type and an excision repair-deficient diploid strain of the yeast, Saccharomyces cerevisiae, was carried out to detect both lethal and genotoxic effects (mutation and mitotic gene conversion) of the sunlight. Exposure of the yeast cells to sunlight 30 to 180 min resulted in a significant level of cell death and a dose-dependent induction of mutations and mitotic gene conversion. The use of a Mylar filter cutting off virtually all of the wavelengths below 312 nm greatly reduced the lethal and genotoxic effects of sunlight. The results of UV measurements and biological studies suggest that an appreciable amount of potentially carcinogenic short UV wavelengths is present in sunlight in the Riyadh area. Therefore, factors other than the lack of biologically significant UV radiation in sunlight appear more likely to be responsible for the reduced incidence of sunburning and skin cancer in this geographical area.

Gene Conversion↗
PubMed1995

Sunlight--can it prevent as well as cause cancer?

Excessive exposure to sunlight is known to damage the skin. However, the emphasis of most studies has been on the consequences of sunlight exposure to fair-skinned individuals, and the situation of people with heavy skin pigmentation residing in, or migrating to, geographic locations with limited sunlight incidence has been largely neglected. Recent epidemiological studies suggested the hypothesis that sunlight deprivation, and the associated reduction in the circulating levels of vitamin D3 (vit D3) derivatives may lead to the increased incidence of the carcinomas of the breast, colon, and prostate. Two endocrine pathways may mediate these effects. The pineal function can potentially be involved, but the formation of vit D3 derivatives is gaining credibility as a mechanism for the retardation of cancer progression. Evidence is accumulating that such compounds, e.g., 1,25-dihydroxyvitamin D3 (1,25D3) induce differentiation of several neoplastic cell types, arrest or retard their proliferation, and act as chemopreventive agents in animal carcinogenesis. We also propose that the antineoplastic effects of vit D3 derivatives are exerted at several steps in tumor progression and that immunomodulating effects of 1,25D3 may contribute to these effects of sunlight. The recent findings that common cancers, e.g., carcinoma of the prostate and the breast, behave more aggressively in black Americans than in white Americans may be explained on this basis. Although more data are needed on the effects of sunlight on the circulating levels of 1,25D3, a corollary of this hypothesis is that there should be no broad condemnation of moderate sunlight exposure, as it may be available in insufficient amounts to some Americans.

Animals↗
PubMed1994

Epidermis and serum protect retinol but not retinyl esters from sunlight-induced photodegradation.

Sunlight-induced photodegradation of retinyl esters and retinol in human skin, blood and cultured keratinocytes was investigated. Using high-performance liquid chromatography with an extraction method that avoided saponification, the analysis of human foreskin (Caucasian) showed that levels of retinyl esters and retinol were approximately 3.5 and 5.0 times higher, respectively, in the epidermis than in the dermis. Upon irradiation by sunlight, a significant reduction in epidermal retinyl esters was observed in both summer and winter. However, epidermal retinol, dermal retinol and dermal retinyl esters did not show statistically significant reductions. When serum from volunteers who had taken a large dose of retinyl palmitate to elevate serum retinyl esters was exposed to sunlight, the retinyl esters in the serum rapidly disappeared after 10 min of exposure--similar to the photodegradation seen for retinyl palmitate in an organic solvent. While retinol in an organic solvent rapidly photodegraded similar to serum retinyl palmitate, serum retinol slowly declined upon sunlight irradiation. When cultured keratinocytes that took-up 3H-retinol and thereafter contained 3H-retinyl esters and 3H-retinol were exposed to sunlight, 80% of the 3H-retinyl esters disappeared upon sunlight irradiation whereas only about 20% of the 3H-retinol did so. These results suggest that the epidermis, serum and keratinocytes selectively protect retinol from sunlight-induced photodegradation. It is most likely that serum retinol-binding protein and cellular retinol-binding protein protect retinol, a vital epithelial growth factor, from photodegradation.

Blood↗
PubMed2001

Similarities in sunlight-induced mutational spectra of CpG-methylated transgenes and the p53 gene in skin cancer point to an important role of 5-methylcytosine residues in solar UV mutagenesis.

In the p53 gene of human sunlight-associated skin cancers, 35 % of the mutations involve trinucleotide sequences with the rare base 5-methylcytosine (5'PymCG). In order to determine the involvement of 5-methylcytosine in sunlight-induced mutations, we have analyzed the cII transgene in mouse cells, a mutational target gene that we found is methylated at most CpG sequences. We report that the mutational spectra produced by irradiation with 254 nm UVC radiation and simulated sunlight, respectively, differ most dramatically by the much higher involvement of dipyrimidine structures containing 5-methylcytosine in the solar UV mutation spectrum (32 % versus 9 % of all mutations). A distinct mutational hotspot induced by simulated sunlight occurs at a sequence 5'TmCG and is associated with high levels of cis-syn cyclobutane pyrimidine dimer formation. A comparison of sunlight-induced mutational spectra of the cII and lacI transgenes, as well as the p53 gene in skin tumors, shows that 5-methylcytosine is involved in 25 to 40 % of all mutations in all three systems. The combined data make a strong case that cyclobutane pyrimidine dimers forming preferentially at dipyrimidine sequences with 5-methylcytosine are responsible for a considerable fraction of the mutations induced by sunlight in mammalian cells.

5-Methylcytosine↗
PubMed1994

A dose-response effect between a sunlight index and age-related cataracts. Italian-American Cataract Study Group.

To explore the existence of a dose-response relationship between sunlight exposure and risk of age-related cataracts, we analyzed data collected from 1008 patients with cataracts and 469 control subjects enrolled in the Italian-American Case-Control Study of Age-Related Cataracts. Fourteen variables related to sunlight exposure history were included in the questionnaire administered to the study participants. A sunlight index was constructed and its relationship to the presence of cataracts was modeled by logistic regression. After adjustments for potential confounding variables and for age and sex, a significant dose-response effect (P = 0.01) was detected between the sunlight exposure index and the presence of pure cortical cataracts. With the exception of corticonuclear cataracts, all the other mixed types of opacity also showed a dose-response association with the sunlight index. These data support the hypothesis that sunlight exposure is a risk factor in the development of cortical cataracts, and demonstrate the existence of a dose-response relationship in this association.

Aged↗
PubMed2004

Sunlight-mediated activation of an inert polymer surface for covalent immobilization of a protein.

Polystyrene, polypropylene, and polyethylene surfaces were activated by exposing 1-fluoro-2-nitro-4-azidobenzene coated surface to sunlight. Sunlight intensity of 26,300 lux was found optimum beyond which no appreciable increase in activation was observed. Five-minutes sunlight exposure gave better activated surface than 5 min 365-nm UV light exposure. The efficacy of sunlight-mediated activated surfaces was demonstrated by covalently immobilizing proteins onto them. Horseradish peroxidase when immobilized onto the sunlight-activated surfaces showed more than twofold increase in immobilization than the surface without activation. Thus, sunlight being a versatile, eco-friendly, and clean energy source can be a potential alternative for activation of inert surface for covalent attachment of biomolecule such as protein, DNA, or carbohydrate.

Azides↗
PubMed2000

Commonly recommended daily intake of vitamin D is not sufficient if sunlight exposure is limited.

OBJECTIVES: Sunlight exposure of the skin is known to be the most important source of vitamin D. The aims of this study were: (i) to estimate vitamin D status amongst sunlight-deprived individuals (veiled Arab women, veiled ethnic Danish Moslem women and Danish controls); and (ii) through food intake analysis to estimate the oral intake of vitamin D necessary to keep a normal vitamin D status in sunlight-deprived individuals. DESIGN: Cross-sectional study amongst randomly selected Moslem women of Arab origin living in Denmark. Age-matched Danish women were included as controls. To control for racial differences, a group of veiled ethnic Danish Moslem women (all Caucasians) was included. SETTING: Primary Health Care Centre, City Vest and Department of Endocrinology and Metabolism C, University Hospital of Aarhus, Aarhus Amtssygehus, Aarhus, Denmark. SUBJECTS: Sixty-nine Arab women (60 veiled, nine non-veiled) and 44 age-matched Danish controls were randomly selected amongst patients contacting the primary health care centre for reasons other than vitamin D deficiency. Ten ethnic Danish Moslem women were included through a direct contact with their community. MAIN OUTCOME MEASURES: Serum levels of 25-hydroxyvitamin D were used as estimates of vitamin D status. Intact parathyroid hormone (PTH) was used to control for secondary hyperparathyroidism. Alkaline phosphatase and bone-specific alkaline phosphatase were used as markers for osteomalacic bone involvement. Oral intake of vitamin D and calcium were estimated through a historical food intake interview performed by a trained clinical dietician. RESULTS: Veiled Arab women displayed extremely low values of 25-hydroxyvitamin D: 7.1 +/- 1.1 nmol L-1, compared with 17.5 +/- 2. 3 (P < 0.002) in ethnic Danish Moslems and 47.1 +/- 4.6 (P < 10-17) in Danish controls. PTH was increased amongst veiled Arab women: 15. 6 +/- 1.8 pmol L-1, compared with 5.7 +/- 1.4 in ethnic Danish Moslems and 2.7 +/- 0.3 (P < 10-6) in Danish controls. The vitamin D intake (including food supplementation) was very low amongst Arab women: 1.04 microg day-1, compared with 13.53 amongst ethnic Danish Moslems and 7.49 amongst Danish controls (P < 0.0005). CONCLUSIONS: Severe vitamin D deficiency is prevalent amongst sunlight-deprived individuals living in Denmark. In veiled Arab women, vitamin D deficiency is the result of a combination of limitations in sunlight exposure and a low oral intake of vitamin D. The oral intake of vitamin D amongst veiled ethnic Danish Moslems was, however, very high, at 13.53 microgram (approximately 600 IU), but they were still vitamin D-deficient. Our results suggest that the daily oral intake of vitamin D in sunlight-deprived individuals should exceed 600 IU; most probably it should be 1000 IU day-1 to secure a normal level of 25-hydroxyvitamin D. This finding is in contrast with the commonly used RDA (recommended daily allowance) for adults in Europe: 200 IU day-1.

Adult↗
PubMed1999

Sensitivities and gene-expressions of Escherichia coli mutants deficient in DNA repair and reactive oxygen species scavenging capacity exposed to natural sunlight.

Sensitivities to sunlight of Escherichia coli mutants deficient in DNA repair capacities such as excision and recombination repair and their wild-type strain were compared. Higher sensitivities to sunlight were clearly observed in the mutant than wild-type strain, indicating that exposure to sunlight induces DNA damage which is repaired by DNA repair mechanisms. In order to assess the role of generation of reactive oxygen species (ROS) in DNA damage induced by exposure to natural sunlight, the kat-sod assay was performed using E. coli mutant strains deficient in ROS scavenging enzymes such as superoxide dismutase and/or catalase. Natural sunlight induced a significant generation of ROS, suggesting a possibility that sunlight induced ROS may be involved in DNA damage in bacterial cells.

Adenosine Triphosphatases↗
PubMed1994

Contributions of vitamin D intake and seasonal sunlight exposure to plasma 25-hydroxyvitamin D concentration in elderly women.

We investigated the contributions (1.00-8.03 micrograms/d, or 40-321 IU/d) of vitamin D intake and seasonal sunlight exposure to plasma 25(OH)D in 59 healthy women aged 70-97 y with a mean total vitamin D intake of 8.58 micrograms/d (343 IU/d). In the summer and winter, each subject had a fasting blood measurement and assessments of vitamin D intake and sunlight exposure. Vitamin D intake was significantly correlated with plasma 25(OH)D in the summer (r = 0.52, P < 0.01) and winter (r = 0.63, P < 0.01). The influence of sunlight exposure measured in the summer on the 25(OH)D concentration was dependent on the vitamin D intake. In subjects with lower vitamin D intakes (1.00-8.03 micrograms/d, or 40-321 IU/d), the wintertime 25(OH)D concentrations of those with low and high sunlight exposure were comparable. In subjects with higher vitamin D intakes (11.15-28.68 micrograms/d, or 446-1147 IU/d), however, the wintertime 25(OH)D concentrations of those with high sunlight exposure were lower than those with lower exposure [63.8 +/- 3.9 and 80.6 +/- 6.7 nmol/L, respectively, P = 0.066; P (intake by exposure interaction) < 0.05]. This suggests that the contribution of vitamin D intake to plasma 25(OH)D concentration may be influenced by sunlight exposure.

Aged↗
PubMed1996

Relationship between sunlight exposure and a key genetic alteration in basal cell carcinoma.

BACKGROUND: Basal cell carcinoma (BCC) of the skin is the most common cancer in humans. Epidemiologic studies implicate sunlight exposure as one risk factor, but the limited association between BCCs and UVB radiation (i.e., UV radiation of a wavelength of 280-320 nm) suggests that additional factors must be involved. At the molecular level, not much is known about the role of specific environmental agents in the pathogenesis of BCCs. Point mutations of the types produced by UVB radiation are seen in the p53 gene (also known as TP53; chromosome 17p) of 40%-56% of BCCs. Loss of heterozygosity (LOH) on chromosome 9q22, however, is the most frequent genetic alteration in these tumors, and its causative agent is unknown. PURPOSE: We investigated whether the genetic alteration in chromosome 9 is common to all clinical subtypes of BCCs and whether inactivation of this putative tumor suppressor is related to sunlight exposure. The presence of UVB radiation-related point mutations in the p53 gene was used as an internal control for sunlight exposure to the precursor cells. METHODS: Tumor and blood samples were obtained from skin cancer patients by a surgeon who used Mohs' micrographic surgical technique. Clinical information on each tumor included location, size, histologic, subtype and whether it was primary or recurrent and sporadic or hereditary. Sixty BCCs from 58 patients were evaluated for LOH with 12 polymorphic markers that span chromosome 9. A subset of 18 tumors was evaluated for point mutations in exons 2-11 of the p53 gene, and a subset of 26 tumors was evaluated for LOH by use of a polymorphism in exon 4 of the p53 gene. Associations between tumor characteristics and molecular alterations were tested by a two-tailed chi-squared analysis or a two-tailed Fisher's exact test, depending on sample size. RESULTS: In a clinically diverse series of 47 informative tumors, 32 (68%) showed LOH for chromosome 9q markers, irrespective of histologic characteristics or clinical behavior. Forty-four (94%) of the 47 tumors were from sun-exposed areas of the body, defined as the head and neck in both sexes, shoulders or chest in males, and legs in females. No association was found between chromosome 9q LOH and sunlight exposure, as assessed by either the location of tumors on the body or the presence of UVB radiation-related p53 mutations. Of note, there was a striking difference between the frequency of LOH on chromosome 17p (two [12.5%] of 16 informative tumors) and on chromosome 9q (32 [68%] of 47 informative tumors; P < .001). CONCLUSIONS: Inactivation of a gene on chromosome 9q22 may be a necessary event for basal cell carcinogenesis. The pathogenesis of mutations in this gene may involve factors other than sunlight in a large proportion of tumors. IMPLICATIONS: The limited association between sunlight exposure and BCC incidence may reflect an etiologic contribution of additional environmental agents.

Adult↗
PubMed1989

Sunlight, skin sensitivity, and senile cataract.

This study explores the association between sunlight exposure and senile cataract, taking into account such individual differences as skin sensitivity to sunlight and the use of sun-shielding devices, i.e., sunglasses and hats. A case-control study was conducted among 160 matched pairs of subjects between October 1, 1984 and June 1, 1985 at the University of Iowa Hospitals and Clinics in Iowa City, Iowa. Cases were selected from among all patients admitted for inpatient or outpatient cataract surgery who were at least 40 years old. Controls were selected from among those waiting for a friend or relative who was attending one of the ophthalmology clinics. Controls were matched to the cases on a 1:1 basis on sex and age (+/- one year). No association was observed between history of sunlight exposure and senile cataract. However, independent of sunlight exposure, the cases with nuclear cataracts reported a more severe acute skin response upon exposure to sunlight for the first time in the summer (a severe burn with blistering) than did their age- and sex-matched controls (McNemar odds ratio (OR) = 1.73, 95% confidence interval (CI): 1.03-2.91). In addition, independent of sunlight exposure, the male controls reported a greater average lifetime use of head coverings in summer which shaded their eyes from the sun than did their age- and sex-matched cases (McNemar OR = 0.48, 95% CI: 0.25-0.94).

Adult↗
PubMedDate not supplied

The effect of sunlight on postoperative analgesic medication use: a prospective study of patients undergoing spinal surgery.

OBJECTIVE: Exposure to natural sunlight has been associated with improvement in mood, reduced mortality among patients with cancer, and reduced length of hospitalization for patients who have experienced myocardial infarction. Our aim was to evaluate whether the amount of sunlight in a hospital room modifies a patient's psychosocial health, the quantity of analgesic medication used, and the pain medication cost. METHODS: A prospective study of pain medication use was conducted in 89 patients undergoing elective cervical and lumbar spinal surgery where they were housed on either the "bright" or "dim" side of the same hospital unit. Analgesic medication was converted to standard morphine equivalents for interpatient comparison. The intensity of sunlight in each hospital room was measured daily and psychologic questionnaires were administered on the day after surgery and at discharge. RESULTS: Patients staying on the bright side of the hospital unit were exposed to 46% higher-intensity sunlight on average (p = .005). Patients exposed to an increased intensity of sunlight experienced less perceived stress (p = .035), marginally less pain (p = .058), took 22% less analgesic medication per hour (p = .047), and had 21% less pain medication costs (p = .047). Age quartile was the only other variable found to be a predictor of analgesic use, with a significant negative correlation (p <.001). However, patients housed on the bright side of the hospital consistently used less analgesic medications in all age quartiles. CONCLUSION: The exposure postoperatively of patients who have undergone spinal surgery to increased amounts of natural sunlight during their hospital recovery period may result in decreased stress, pain, analgesic medication use, and pain medication costs.

Age Factors↗
PubMed1991

Sunlight and the survival of enteric bacteria in natural waters.

Escherichia coli and some salmonellas were exposed in seawater and freshwater to natural sunlight, visible light of comparable intensity, and light containing a similar proportion of u.v. as natural sunlight but of a much lower intensity. Direct viable bacterial counts and culturable counts on selective and non-selective media were made at intervals. The rate of decrease in numbers of culturable bacteria was significantly faster in seawater than in freshwater when exposed to natural sunlight. No significant difference was found between the rates of decrease in numbers of culturable bacteria in seawater and those in freshwater when bacteria were exposed to light with a small u.v. component of similar intensity. The effect of salinity no loss of culturability is, therefore, more significant in the presence of u.v. radiation. Direct counts by the acridine orange direct viable count method decreased much more slowly than the culturable counts in seawater but comparably with culturable counts in freshwater in natural sunlight. Direct viable counts and culturable counts decreased at a similar rate in seawater and in freshwater in visible light. This may signify the evolution of enteric bacteria towards a viable but non-culturable form in seawater when exposed to natural sunlight. The presence of humic acids significantly reduced loss of culturability but only in low salinity conditions. Salinity appears to be an important factor influencing culturability in bacteria exposed to sunlight.

Escherichia coli↗
PubMed1992

Cumulative sunlight exposure and the risk of developing skin cancer in Florida.

Epidemiologic evidence suggests that the risk of developing skin cancer is higher in certain geographic regions where sunlight is excessive. Even in such high risk regions, two distinct populations of long-term residents exist: people with, and people without skin cancer. We have compared the quantitative lifetime sunlight exposure between 11 nonmelanoma skin cancer patients who have lived in South Florida for 23.7 +/- 5.1 years and 9 age-matched normal, healthy individuals who have lived in South Florida for 23.4 +/- 4.1 years. An estimation of personal cumulative sunlight exposure was determined for each subject from data collected through detailed interviews. We found that there was no detectable, significant quantitative difference in cumulative sunlight exposure during life between these two groups. Because these individuals had previously been phenotyped for the effects of ultraviolet-B (UVB) radiation on induction of contact hypersensitivity, our results suggest that UVB-susceptibility may be a better indicator of skin cancer risk than cumulative lifetime sunlight exposure. Thus, although there is little doubt that sunlight exposure is an important factor in the development of skin cancer, our results emphasize the importance of host genetic factors in the pathogenesis of this disease.

Aged↗