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At least 253 records · Page 14Linked to original sources
PubMed1998

Increased levels of enkephalin following natural sunlight (combined with salt water bathing at the Dead Sea) and ultraviolet A irradiation.

The opioid peptides enkephalins have been shown to modulate inflammatory responses and keratinocyte proliferation and differentiation. Furthermore, increased levels of enkephalin are present in psoriatic lesions. The purpose of the present study was to determine the effect of natural sunlight combined with salt water bathing in the Dead Sea on the methionine-enkephalin (e.n.k.) level in psoriatic skin. Ten patients were treated at the Dead Sea for 4 weeks, and keratotome biopsies were obtained before and after treatment. The amount of enkephalin extracted from the biopsies was measured by radioimmunoassay. Treatment at the Dead Sea resulted in a complete clinical clearance of psoriasis, and immunohistochemical stainings of lesional skin showed that the treatment decreased both epidermal thickness/parakeratosis and the dermal infiltration of CD3- and CD68-positive cells, although the number of CD3- and CD68-positive cells became normal in only two of the 10 cases. However, there was only a slight decrease in the mean enk levels (21%). Furthermore, the level of enk was high in non-lesional psoriatic skin after treatment at the Dead Sea, and immunostaining showed that, in some patients, the treatment induced a mild epidermal hyperplasia and a dermal infiltration of CD3- and CD68-positive cells. Enkephalin-like immunoreactivity was detected in the cytoplasm of both epidermal keratinocytes and dermal infiltrating cells. To determine whether the relatively high skin enk levels after treatment at the Dead Sea was caused by ultraviolet (UV) radiation, normal volunteers were exposed to a single dose of UVA and UVB (2 minimal erythema doses). UVA, but not UVB, irradiation stimulated the mean enk level in the irradiated skin by about sixfold. Furthermore, multiple whole-body UVA irradiations not only resulted in increased skin levels of enk, but also in increased plasma levels. In conclusion, natural sunlight combined with salt water bathing cleared psoriasis without causing a significant decrease in lesional enk levels. Furthermore, non-lesional enk levels were increased. These findings may be the result of a direct stimulatory effect of UVA irradiation on enk formation in the skin. It is possible that the increased circulating levels of enk after UV exposure may contribute to the beneficial effects of UVA irradiation.

Adult↗
PubMed2006

[Maximilian Mehl and the treatment with concentrated sunlight].

In 1889, a chance observation made by Maximilian Mehl, an officer of the Berlin police force, lead him to develop a new method of treating Lupus Vulgaris with concentrated sunlight. Although first therapies proved the efficacy of this method, scientific medicine showed little interest. But Mehl found recognition among supporters of natural healing methods who saw their principles confirmed by his discovery. Mehl's tentative therapy was superseded by technological methods of sunlight treatment, as developed by the Danish doctor Niels Ryberg Finsen. In 1903 Finsen was awarded the Nobel Prize for his work while Mehl's discovery remained practically unknown. This episode in the history of medicine demonstrates how the recognition of a new method not only depends on criteria of its efficacy, but equally so on the degree of its conformity with preconceived notions and accepted standards.

Berlin↗
PubMed2003

Roles of Saccharomyces cerevisiae DNA polymerases Poleta and Polzeta in response to irradiation by simulated sunlight.

Sunlight causes lesions in DNA that if unrepaired and inaccurately replicated by DNA polymerases yield mutations that result in skin cancer in humans. Two enzymes involved in translesion synthesis (TLS) of UV-induced photolesions are DNA polymerase eta (Poleta) and polymerase zeta (Polzeta), encoded by the RAD30A and REV3 genes, respectively. Previous studies have investigated the TLS roles of these polymerases in human and yeast cells irradiated with monochromatic, short wavelength UVC radiation (254 nm). However, less is known about cellular responses to solar radiation, which is of higher and mixed wavelengths (310-1100 nm) and produces a different spectrum of DNA lesions, including Dewar photoproducts and oxidative lesions. Here we report on the comparative cytotoxic and mutagenic effects of simulated sunlight (SSL) and UVC radiation on yeast wild-type, rad30Delta, rev3Delta and rev3Delta rad30Delta strains. The results with SSL support several previous interpretations on the roles of these two polymerases in TLS of photodimers and (6-4) photoproducts derived from studies with UVC. They further suggest that Poleta participates in the non-mutagenic bypass of SSL-dependent cytosine-containing Dewar photoproducts and 8-oxoguanine, while Polzeta is mainly responsible for the mutagenic bypass of all types of Dewar photoproducts. They also suggest that in the absence of Polzeta, Poleta contributes to UVC- and SSL-induced mutagenesis, possibly by the bypass of photodimers containing deaminated cytosine.

Base Sequence↗
PubMed1993

Simulated influence of leaf geometry on sunlight interception and photosynthesis in conifer needles.

The light interception capabilities of individual conifer needles are governed by their cross-sectional geometry and their orientation to sunlight. Leaf cross sections typical of conifer tree species were modeled to quantify the interception of direct sunlight over a range of incident light angles. The needle shapes exhibited by Abies nordmanniana Spach, Picea asperata Master, Pinus cembra L., P. monophylla Torr & Frém., and P. sylvestris L. were selected because they are representative of the range of geometric shapes found in conifer tree species. Calculated light interception values were compared to corresponding predictions for a laminar broadleaf. Estimates of carbon gain were derived from computed incident light integrated over the leaf cross section and a representative curve of conifer photosynthetic response to light. Flat leaf cross sections (e.g., Abies nordmanniana) with high surface area to volume ratios (> 6) intercepted more light per unit area at high angles of incidence than thick leaves. Thick leaves (e.g., Pinus cembra) intercepted more light at low angles of incidence than at high angles of incidence. Needles of Pinus monophylla had no angular dependence for light interception because of their circular cross section. Large differences in estimated CO(2) assimilation occurred among the species, especially when CO(2) uptake was expressed on a unit volume basis. A maximum uptake of 67.9 mmol CO(2) m(-3) s(-1) was predicted for A. nordmanniana compared to a minimum of 39.7 mmol m(-3) s(-1) for P. monophylla. A greater angular dependence occurred for estimates of CO(2) uptake than for estimates of light interception.

Journal Article↗
PubMed1993

The suitability of SunCheck patches and Tanscan cards for monitoring the sunburning effectiveness of sunlight.

UV-sensitive products which undergo a colour change on exposure to UV radiation are available for use by the general public. We have evaluated SunCheck patches of various sensitivities, and Tanscan UV sensor cards, in terms of their temperature stability, wavelength response and response to sunlight. The products exhibited no perceptible colour change when the temperature was maintained at 45 degrees C for 4 hours; on exposure to monochromatic radiation, the sensitivity peaked at a wavelength of 335 and 355 nm for SunCheck and Tanscan, respectively; the response to sunlight under clear conditions was reasonably consistent, with the coefficient of variation for each type of material ranging between 12.5 and 27%. These products are based on the incorrect concept that there is a 'safe' dose of UV radiation. Thus, they cannot be recommended to the public as a reliable way of reducing the risk of skin cancer.

Dermatology↗
PubMed1983

Lemon juice, sunlight, and tattoos.

In folklore, tattoos are thought to fade if rubbed with lemon juice and exposed to sunlight. The authors tested this hypothesis on shaved, tattooed rats. Tattooed controls were used. Additional substances and conditions were included in the study (tretinoin gel, liquid nitrogen, and dermabrasion). The authors conclude that India ink tattoos do not fade significantly with sunlight and lemon juice nor with the application of tretinoin gel, liquid nitrogen, or combinations thereof.

Animals↗
PubMed2004

Sensitivity studies for space-based measurement of atmospheric total column carbon dioxide by reflected sunlight.

The feasibility of making space-based carbon dioxide (CO2) measurements for global and regional carbon-cycle studies is explored. With the proposed detection method, we use absorption of reflected sunlight near 1.58 microm. The results indicate that the small (degrees 1%) changes in CO2 near the Earth's surface are detectable provided that an adequate sensor signal-to-noise ratio and spectral resolution are achievable. Modification of the sunlight path by scattering of aerosols and cirrus clouds could, however, lead to systematic errors in the CO2 column retrieval; therefore ancillary aerosol and cloud data are important to reduce errors. Precise measurement of surface pressure and good knowledge of the atmospheric temperature profile are also required.

Journal Article↗
PubMed1991

The repair of DNA damages induced in normal human skin fibroblasts exposed to simulated sunlight.

The induction and repair of DNA damages produced by exposure of normal human skin fibroblasts to the simulated sunlight produced by a solar simulator were examined. The photoproducts measured were pyrimidine dimers, E. coli endonuclease III-sensitive sites, 6-4 photoproducts, Dewar isomers, DNA-protein crosslinks, and DNA single-strand breaks. The results of these experiments serve to form a basis for the quantitation of damages induced by exposure to sunlight.

Adult↗
PubMed2004

Sunlight and the 10-year incidence of age-related maculopathy: the Beaver Dam Eye Study.

OBJECTIVE: To examine the association of sunlight exposure and indicators of sun sensitivity with the 10-year incidence of age-related maculopathy (ARM). DESIGN: Population-based cohort study. PARTICIPANTS: We included persons aged 43 to 86 years at the baseline examination from 1988 to 1990, living in Beaver Dam, Wis, of whom 3684 persons underwent 5-year follow-up and 2764 underwent 10-year follow-up. METHODS: Data on sun exposure and indicators of sun sensitivity were obtained from a standardized questionnaire administered at baseline and/or follow-up. We determined ARM status by grading stereoscopic color fundus photographs using the Wisconsin Age-Related Maculopathy Grading System. MAIN OUTCOME MEASURES: Incidence and progression of ARM. RESULTS: While controlling for age and sex, we found that participants exposed to the summer sun for more than 5 hours a day during their teens, in their 30s, and at the baseline examination were at a higher risk of developing increased retinal pigment (risk ratio [RR], 2.99; 95% confidence interval [CI], 1.18-7.60; P =.02) and early ARM (RR, 2.20; 95% CI, 1.02-4.73; P =.04) [corrected] by 10 years than those exposed less than 2 hours per day during the same periods. In participants reporting the highest summer sun exposure levels in their teens and 30s, the use of hats and sunglasses at least half the time during the same periods was associated with a decreased risk of developing soft indistinct drusen (RR, 0.55; 95% CI, 0.33-0.90; P =.02) and retinal pigment epithelial depigmentation (RR, 0.51; 95% CI, 0.29-0.91; P =.02). Participants who experienced more than 10 severe sunburns during their youth were more likely than those who experienced 1 or no burn to develop drusen with a 250-microm diameter or larger (RR, 2.52; 95% CI, 1.29-4.94 [corrected] P =.01) by the 10-year examination. No relationships were found between UV-B exposure, winter leisure time spent outdoors, skin sun sensitivity, or number of bad sunburns experienced by the time of the baseline examination and the 10-year incidence and progression of ARM or its associated lesions. CONCLUSIONS: Few significant relationships between environmental exposure to light and the 10-year incidence and progression of ARM were found in the Beaver Dam Eye Study. Consistent with results from the baseline and 5-year follow-up examinations, significant associations were found between extended exposure to the summer sun and the 10-year incidence of early ARM and increased retinal pigment. A protective effect of hat and sunglasses use by participants while in their teens and 30s against the 10-year incidence of soft indistinct drusen and retinal pigment epithelial depigmentation was also found, but only in those who reported the highest amount of sun exposure during the same periods.

Adult↗
PubMed1998

Differential photohydrodehalogenation reactivity of bromobenzenes (1,2,4-tribromobenzene, 1,2,3,5-tetrabromobenzene) and pentachlorobenzene: sunlight-based remediation.

The photochemical dehalogenation of 1,2,4-tribromobenzene, 1,2,3,5-tetrabromobenzene and pentachlorobenzene in open-air solutions of acetonitrile using natural and artificial sunlight as the irradiation source has been investigated. The regiochemistry of mono-dehalogenation has been determined for 1,2,4-tribromobenzene and 1,2,3,5-tetrabromobenzene. Pentachlorobenzene did not react. 1,2,4-Tribromobenzene yielded three products, 1,4-dibromobenzene, 1,3-dibromobenzene and 1,2-dibromobenzene with isomer percentages of 52 +/- 1%, 39 +/- 2% and 9 +/- 1%, respectively. 1,2,3,5-Tetrabromobenzene yielded 1,3,5-tribromobenzene, 1,2,4-tribromobenzene and 1,2,3-tribromobenzene with relative product percentages of 60 +/- 2%, 29 +/- 2%, 11 +/- 1%.

Biodegradation, Environmental↗
PubMed1991

Sunlight and dysplastic nevus risk. Results of a clinic-based case-control study.

The dysplastic nevus (DN) is the most important risk factor and precursor for malignant melanoma. The authors compared the responses of 132 consecutive cases of DN, 186 consecutive cases of cutaneous melanoma, and 239 controls attending the same subspecialty clinic to questions regarding sun sensitivity, sun exposure, and other possible risk factors. Dysplastic nevus cases were younger than controls and were of a higher social class, as indicated by more years of formal education. Sun sensitivity (assessed by reported depth of tan after multiple exposures) was associated with both DN risk and melanoma risk after controlling for age and education in logistic regression analysis (P = 0.009 and 0.03, respectively), but for DN risk this association was nonlinear: the relative risks (versus deep tan) were 2.3 for average tanners, 2.8 for light tanners, and 1.6 for those who reported practically no tan. Sun exposure measures were not associated with DN risk after controlling for age and education, whether or not depth of tan was controlled in the analysis. These observations suggest a role for either sunlight or a trait linked with sun sensitivity in the development of dysplastic nevi.

Adult↗
PubMed1980

Sunlight-induced mutagenesis and toxicity in L5178Y mouse cells: determination and comparison with other light sources.

Compared to the basis of equal exposure, in joules per square meter (J/m2) the mutagenic and toxic effects in L5178Y mouse lymphoma cells of radiation emitted by some fluorescent lamps and a sunlamp are quantitatively similar to solar radiation effects at the earth's surface. When the relative intensities of radiation are taken into account, the artificial light sources range from 8 to 1/222 times as mutagenic and 4.1 to less than 1/99 times as toxic as sunlight.

Animals↗
PubMed1988

The endocrinology of sunlight and darkness. Complementary roles of vitamin D and pineal hormones.

Information from autoradiographic studies and follow-up indicates that 1,25(OH)2 vitamin D3 (soltriol) is a somatotrophic activator and modulator, regulated by the amount of sunshine and the endocrine status of the individual, with the purpose of promoting development, reproduction, and maintenance of life. Regulation of calcium homeostasis is only one of its many functions. A close link to the pineal hormone system is apparent. Evidence supports the new concept that the skin-derived hormone of sunlight and the pineal hormone(s) of darkness are messengers with comprehensive actions on endocrine, autonomic, sensory, skeletal, and motor functions. In a complementary fashion, both hormone systems appear to correlate biological activities with the daily and seasonal changes of our solar environment.

Animals↗
PubMedDate not supplied

Chemical evolution of the citric acid cycle: sunlight photolysis of the amino acids glutamate and aspartate.

Sunlight photolysis of the amino acids glutamate and aspartate were carried out on 0.1 M aqueous solutions at pH = 7.0. The non-volatile products were identified by GC-MS analysis of derived methyl esters. The major product from glutamic acid was succinic acid, and, analogously, aspartic acid photolyzed to malonic acid. The photochemical oxidative decarboxylation of glutamate parallels its metabolism in modern cells and may provide an evolutionary link between simple amino acids and reactions of the citric acid cycle.

Aspartic Acid↗
PubMed1995

Mutation spectra in Salmonella of sunlight, white fluorescent light, and light from tanning salon beds: induction of tandem mutations and role of DNA repair.

We evaluated the mutagenicity of sunlight (SUN), uncovered coolwhite fluorescent light (FLR), and light from a tanning salon bed (TAN) at the base-substitution allele hisG46 of Salmonella in four DNA repair backgrounds (wild type, uvrB, pKM101, and uvrB + pKM101). Approximately 80% of the radiation emitted by TAN was within the ultraviolet (UV) range, whereas only approximately 10% of the SUN and approximately 1% of the FLR radiation was UV. TAN emitted similar amounts of UVA and UVB, whereas SUN emitted 50-60x and FLR emitted 5-10x more UVA relative to UVB. Based on total dose (UV + visible), the mutagenic potency ranking was TAN > FLR > SUN. Using colony probe hybridization and PCR/DNA sequence analysis, approximately 3000 revertants were analyzed to determine the mutational specificity of the three light sources. The mutation spectra and those induced by 254-nm UV had common features. The uvrB mutation enhanced the mutagenicity of the environmental UV sources more (20-216x) than did the pKM101 plasmid (approximately 20x) relative to wild type DNA repair. All light sources induced equal proportions of transitions and transversions in excision repair-proficient strains, but they induced more transitions relative to transversions in uvrB-containing strains. The majority of the mutations were G.C-->A.T transitions that were induced equally frequently at the first or second position of the CCC codon of the hisG46 allele in all strains except TA1535 (uvrB), where SUN and FLR induced transitions preferentially at the first position, and TAN induced them preferentially at the second position. Identified or presumptive multiple mutations, which constituted the only mutational class enhanced by all three light sources in the presence of uvrB and pKM101 either alone or together, accounted for 3-5% of the induced mutations in the plasmid-containing strains, and their increases (38-82-fold) in TA100 (uvrB, pKM101) were the highest of any mutational class. Of the TAN-induced multiple mutations, 83% (19/23) were CC-->TT tandem transitions. These results show that exposures to the nonsolar environmental UV sources FLR and TAN produce mutations similar to those produced by SUN, a known carcinogen.

Alleles↗
PubMedDate not supplied

The role of sunlight in human cataract formation.

This review summarizes and integrates new findings concerning the role of near-ultraviolet radiation, as is present in sunlight and common artificial light sources, in stimulating human and animal cataract formation. Epidemiological and basic research studies are summarized and critical statements concerning them are offered. Although certain questions still remain unanswered, the evidence that near-UV radiation does stimulate cataract formation is very strong. Avoidance of excessive exposure to near-ultraviolet light and the use of protective lenses that filter it out are suggested to prevent the enhancement of human cataract formation by near-UV light.

Animals↗
PubMed1984

Burn injury: sunlight and a single dose of methoxsalen.

A patient is described in whom burn injury, caused by moderate exposure to sunlight in the U.K., was precipitated by undue sensitivity to a photosensitizing agent methoxsalen. This drug, although withdrawn in the UK, is freely available in the Republic of Ireland and many EEC countries for the treatment of psoriasis and acne vulgaris.

Adult↗