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At least 991 records · Page 55Linked to original sources
PubMed1996

The two major spore DNA repair pathways, nucleotide excision repair and spore photoproduct lyase, are sufficient for the resistance of Bacillus subtilis spores to artificial UV-C and UV-B but not to solar radiation.

Bacterial endospores are 1 to 2 orders of magnitude more resistant to 254-nm UV (UV-C) radiation than are exponentially growing cells of the same strain. This high UV resistance is due to two related phenomena: (i) DNA of dormant spores irradiated with 254-nm UV accumulates mainly a unique thymine dimer called the spore photoproduct (SP), and (ii) SP is corrected during spore germination by two major DNA repair pathways, nucleotide excision repair (NER) and an SP-specific enzyme called SP lyase. To date, it has been assumed that these two factors also account for resistance of bacterial spores to solar UV in the environment, despite the fact that sunlight at the Earth's surface consists of UV-B, UV-A, visible, and infrared wavelengths of approximately 290 nm and longer. To test this assumption, isogenic strains of Bacillus subtilis lacking either the NER or SP lyase DNA repair pathway were assayed for their relative resistance to radiation at a number of UV wavelengths, including UV-C (254 nm), UV-B (290 to 320 nm), full-spectrum sunlight, and sunlight from which the UV-B portion had been removed. For purposes of direct comparison, spore UV resistance levels were determined with respect to a calibrated biological dosimeter consisting of a mixture of wild-type spores and spores lacking both DNA repair systems. It was observed that the relative contributions of the two pathways to spore UV resistance change depending on the UV wavelengths used in a manner suggesting that spores irradiated with light at environmentally relevant UV wavelengths may accumulate significant amounts of one or more DNA photoproducts in addition to SP. Furthermore, it was noted that upon exposure to increasing wavelengths, wild-type spores decreased in their UV resistance from 33-fold (UV-C) to 12-fold (UV-B plus UV-A sunlight) to 6-fold (UV-A sunlight alone) more resistant than mutants lacking both DNA repair systems, suggesting that at increasing solar UV wavelengths, spores are inactivated either by DNA damage not reparable by the NER or SP lyase system, damage caused to photosensitive molecules other than DNA, or both.

Bacillus subtilis↗
PubMed1997

Photoreactivation compensates for UV damage and restores infectivity to natural marine virus communities.

We investigated the potential for photoreactivation to restore infectivity to sunlight-damaged natural viral communities in offshore (chlorophyll a, < 0.1 microgram liter-1), coastal (chlorophyll a, ca. 0.2 microgram liter-1), and estuarine (chlorophyll a, ca. 1 to 5 micrograms liter-1) waters of the Gulf of Mexico. In 67% of samples, the light-dependent repair mechanisms of the bacterium Vibrio natriegens restored infectivity to natural viral communities which could not be repaired by light-independent mechanisms. Similarly, exposure of sunlight-damaged natural viral communities to > 312-nm-wavelength sunlight in the presence of the natural bacterial communities restored infectivity to 21 to 26% of sunlight-damaged viruses in oceanic waters and 41 to 52% of the damaged viruses in coastal and estuarine waters. Wavelengths between 370 and 550 nm were responsible for restoring infectivity to the damaged viruses. These results indicate that light-dependent repair, probably photoreactivation, compensated for a large fraction of sunlight-induced DNA damage in natural viral communities and is potentially essential for the maintenance of high concentrations of viruses in surface waters.

Bacteria↗
PubMed2005

Sun protection in renal transplant recipients: urgent need for education.

BACKGROUND: Renal transplant recipients (RTR) are considered as a high-risk group of skin cancer development. OBJECTIVE: The aim of the present studywas to find out the knowledge about the harmfulness of sunlight and the methods of sun protection among RTR. MATERIAL AND METHODS: 151 RTR (91 males and 60 females) were surveyed using a specially designed questionnaire. RESULTS: The knowledge about the danger of sunlight exposure among RTR appeared to be very unsatisfactory. Only 40.4% of patients knew that the development of skin cancer is connected with the exposure to sunlight. Moreover, only 68.2% of investigated individuals considered RTR as a high-risk group of skin cancer development. Although 74.8% of patients were informed about the necessity of sun protection, only 11.3% could explain what the number of the SPF (sun protection factor) means. Females significantly more often knew that RTR are especially predisposed to the development of skin cancers (p = 0.0001) and significantly more frequently could explain what the SPF number means (p = 0.006). 72.8% of RTR (females significantly more often, p = 0.02) made efforts to avoid sunlight irradiation. However, only 5.3% of the examined patients routinely used creams with SPF (females significantly more often, p < 0.0001). More than a half of the patients (62.3%) did not apply any sun protection. CONCLUSIONS: The present study revealed the urgent necessity of education concerning the harmfulness of sunlight and the methods of sun protection among RTR. Moreover, it is postulated that every patient should be routinely examined by a dermatologist in a dedicated transplant patient clinic.

Adult↗
PubMed2006

Parents' knowledge and behaviour concerning sunning their babies; a cross-sectional, descriptive study.

BACKGROUND: For centuries, sunlight has been used for therapeutic purposes. Parents still sun their infants to treat neonatal jaundice, nappy rash or mostly to supply vitamin D for bone development as a consequence of health beliefs. In this study we aimed to assess knowledge and behaviour of parents about benefits of sunlight and sun protection. METHODS: In this study, parents attending to governmental primary healthcare units for their children's routine vaccinations, upon their informed consent, were consecutively enrolled during one month. Data were collected by a semi-structured questionnaire. RESULTS: The mean age of 118 enrolled parents and their babies were 27.9 +/- 6.5 years and 8.3 +/- 5.8 months, respectively. Most of the participants were mothers (93.2%), housewives (81.4%) with an educational level of > or =6 years (71.2%). Sunlight was considered beneficial for bone development (86.4%), diaper rash (5.9%) and neonatal jaundice (12.7%). In case of neonatal jaundice 72.0% of the participants reported that they would consult a physician. Most of the participants (82.2%) were sunning their babies outdoors. Nearly half (49.7%) of them got this information from medical staff. Fifty two percent of the parents were sunning their babies before 10-11 a.m. and/or after 3 p.m. Only 13.6% of parents reported using sunscreen for their babies, and the majority of them were using sun protecting factor > or = 15. One forth of the sunscreen users was using sunscreen according to their physicians' advice. CONCLUSION: Most of the participants were aware of the benefits of sunlight; especially for bone development. However they were displaying inappropriate behaviour while sunning their babies for health reasons. More education should be given to parents about the danger of sunlight at primary health care units while advising to sun their babies, if any.

Adult↗
PubMedDate not supplied

Photoreactivation in Paramecium tetraurelia under conditions of various degrees of ozone layer depletion.

Photoreactivation (PR) is an efficient survival mechanism that helps protect cells against the harmful effects of solar-ultraviolet (UV) radiation. The PR mechanism involves photolyase, just one enzyme, and can repair DNA damage, such as cyclobutane-pyrimidine dimers (CPD) induced by near-UV/blue light, a component of sunlight. Although the balance of near-UV/blue light and far-UV light reaching the Earth's surface could be altered by the atmospheric ozone layer's depletion, experiments simulating this environmental change and its possible effects on life have not yet been performed. To quantify the strength of UVB in sunlight reaching the Earth's surface, we measured the number of CPD generated in plasmid DNA after UVB irradiation or exposure to sunlight. To simulate the increase of solar-UV radiation resulting from the ozone layer depletion, Paramecium tetraurelia was exposed to UVB and/or sunlight in clear summer weather. PR recovery after exposure to sunlight was complete at a low dose rate of 0.2 J/m2 x s, but was less efficient when the dose rate was increased by a factor of 2.5 to 0.5 J/m2 x s. It is suggested that solar-UV radiation would not influence the cell growth of P. tetraurelia for the reason of high PR activity even when the ozone concentration was decreased 30% from the present levels.

Animals↗
PubMed1987

Photosynthesis of vitamin D in the skin: effect of environmental and life-style variables.

Exposure to sunlight continues to play a major role in providing adequate vitamin D nutrition for most of the population of the world, including those who live in countries that practice fortification of dairy, margarine, and cereal products with vitamin D. During exposure to sunlight, the high-energy UV photons (290-315 nm) penetrate the epidermis and photolyze 7-dehydrocholesterol (provitamin D3) to previtamin D3. Once formed, previtamin D3 undergoes a thermally induced isomerization to vitamin D3 that takes 2-3 days to reach completion. Melanin effectively competes with provitamin D3 for the UV radiation that enters the epidermis and limits its photolysis to previtamin D3. However, this is not the major factor that prevents excess production of vitamin D in the skin of people who are constantly exposed to sunlight. During the initial exposure to sunlight, provitamin D3 is efficiently converted to previtamin D3. However, because previtamin D3 is photolabile, continued exposure to sunlight causes the isomerization of previtamin D3, principally to lumisterol. Thus, no more than 10-20% of the initial provitamin D3 concentrations ultimately end up as previtamin D3. Aging, sunscreens, seasonal changes, time of day, and latitude also significantly affect the cutaneous production of this vitamin-hormone.

Aging↗
PubMed1997

Melanoma and sunscreen use: need for studies representative of actual behaviours.

Experiments in rodents and humans have shown the ability of sunscreens to prevent UVB-induced skin cancers. Sunscreen use has thus become part of the panoply for melanoma prevention. However, results from epidemiological investigations indicate that sunscreen use could be a risk rather than a protective factor for melanoma. This article discusses possible explanations for discrepancies between experimental and observational results, suggesting that experiments did not reproduce usual human behaviours towards the sunlight. Also, marketing of sunscreens fosters unconsidered exposure to sunlight through associating sunscreen use to the acquisition of a 'safe suntan', or to the possibility to let children go naked into the sunlight without incurring sunburns. It has therefore been hypothesized that, because it prevents sunburn, sunscreen use allows prolonged exposure to sunlight. If this hypothesis holds, modern sunscreens with high protection factor could also represent a threat if their use is motivated by the desire of unrestricted exposure to sunlight. To explore this hypothesis, the design of a retrospective cohort study is presented, including children 5-7 years old, with the total body naevi count as principal endpoint. This study will have the opportunity to examine the qualities of modern sunscreens among young children.

Animals↗
PubMed1995

Vitamin D deficiency in homebound elderly persons.

OBJECTIVE: To assess the vitamin D status in homebound, community-dwelling elderly persons; sunlight-deprived elderly nursing home residents; and healthy, ambulatory elderly persons. DESIGN: A cohort analytic study. PARTICIPANTS: Of 244 subjects at least 65 years old, 116 subjects (85 women and 31 men) had been confined indoors for at least 6 months, either in private dwellings in the community (the Hopkins Elder Housecall Program) or in a teaching nursing home (The Johns Hopkins Geriatrics Center). The 128 control subjects, a healthy ambulatory group, came from the Baltimore Longitudinal Study on Aging. All subjects were free of diseases or medications that might interfere with their vitamin D status. MAIN OUTCOME MEASURES: Serum levels of 25-hydroxyvitamin D (25-OHD) and 1,25-dihydroxyvitamin D (1,25-[OH]2D) were measured in all subjects. In a subgroup of 80 subjects, serum levels of intact parathyroid hormone (PTH), ionized calcium, and osteocalcin and intake of vitamin D (through 3-day food records) were assessed. A randomly selected cohort of sunlight-deprived subjects also had serum levels of vitamin D binding protein measured. RESULTS: In sunlight-deprived subjects overall, the mean 25-OHD level was 30 nmol/L (12 ng/mL) (range, < 10 to 77 nmol/L [< 4 to 31 ng/mL]) and the mean 1,25-(OH)2D level was 52 pmol/L (20 pg/mL) (range, 18 to 122 pmol/L [7 to 47 pg/mL]). In the sunlight-deprived subjects, 54% of community dwellers and 38% of nursing home residents had serum levels of 25-OHD below 25 nmol/L (10 ng/mL) (normal range, 25 to 137 nmol/L [10 to 55 ng/mL]). A significant inverse relationship existed between 25-OHD (ie, Log [25-OHD]) and PTH when they were analyzed together (r = -0.42; R2 = 0.18; P < .001) and for each cohort separately. All other parameters measured, except ionized calcium, differed significantly from the Baltimore Longitudinal Study Group means. The mean (SD) daily intakes of vitamin D (121 [132] IU) and calcium (583 [322] mg) were below the recommended dietary allowance only in the community-dwelling homebound population. The mean vitamin D binding protein level in the sunlight-deprived subgroup was in the normal range. CONCLUSIONS: Despite a relatively high degree of vitamin supplementation in the United States, homebound elderly persons are likely to suffer from vitamin D deficiency.

Aged↗
PubMed2005

Effects of riboflavin on the phototransformation of benzo[a]pyrene.

Riboflavin (Vitamin B2) is a natural dye-sensitizer habitually present in natural waters. Effects of riboflavin as photosensitizer on the transformation of benzo[a]pyrene (BaP) (10 microM) in the aqueous-organic solvent (water/acetonitrile/methanol 50/40/10) were investigated in this study. The photolysis half life of BaP in solution containing 50 microM riboflavin was 5 min, compared to 98 min in the absence of riboflavin. The rate of phototransformation of BaP increased as the concentration of riboflavin was raised from 10 microM to 100 microM under both natural sunlight and UVA irradiation. The half life of BaP in the presence of 50 microM riboflavin was 10.6 min and 43.1 min when exposed to visible range of natural sunlight and UVA irradiation respectively. Riboflavin decomposes under natural sunlight. Lumichrome, a principal photoproduct of riboflavin, was shown to photosensitize BaP under natural sunlight after photolysis of riboflavin. Our study indicated that other photoproducts from riboflavin, such as lumiflavin, were also involved in the phototransformation of BaP under sunlight when riboflavin diminished. The major photoproducts in the photolysis of BaP were identified as 1,6-benzo[a]pyrene-dione, 3,6-benzo[a]pyrene-dione, 6,12-benzo[a]pyrene-dione by using high performance liquid chromatography (HPLC). All these products were detected in the samples which were irradiated under different light sources and in the presence or absence of riboflavin. The possible phototransformation mechanism was discussed.

Benzo(a)pyrene↗
PubMed1996

Relation between geographic variability in kidney stones prevalence and risk factors for stones.

To determine whether geographic variability in rates of kidney stones in the United States was attributable to differences in personal and environmental exposures, the authors examined cross-sectional data that included information on self-reported, physician-diagnosed kidney stones collected from 1,167,009 men and women, aged > or = 30 years, recruited nationally in 1982. Information on risk factors for stones including age, race, education, body mass, hypertension, and diuretic and vitamin C supplement use was obtained by self administered questionnaire. Consumption of milk, coffee, tea, soft drinks, and alcohol was based on food frequency data. Indices of ambient temperature and sunlight level were assigned to subjects based on state of residence. Stones were nearly twice as prevalent in the Southeast as in the Northwest among men and women. Ambient temperature and sunlight indices were independently associated with stones prevalence after controlling for other risk factors for stones. Regional variation was eliminated for men and greatly reduced for women after adjustment for temperature, sunlight, and beverage consumption. Other factors appeared to not contribute to regional variation. These results provide evidence that ambient temperature and sunlight levels are important risk factors for stones and that differences in exposure to temperature and sunlight and beverages may contribute to geographic variability.

Adult↗
PubMed1996

Sunburn, sunscreen, and melanoma.

This paper reviews the current epidemiologic and experimental evidence regarding the effect of sunburns on cutaneous malignant melanoma and the possible effectiveness of sunscreens in preventing those effects. Although there is growing agreement that sunlight exposure, particularly the ultraviolet wavelengths in solar radiation, contributes to the etiology of cutaneous malignant melanoma, there are at present insufficient data on the effective ultraviolet waveband and whether the use of sunscreens may be useful in preventing melanoma. The main obstacle in answering this question is that the exact role of sunlight in the pathogenesis of melanoma still remains undefined. However, new experimental animal models are now available that will assist in determining and defining the mechanism of initiation and promotion of melanoma by sunlight and, particularly, ultraviolet radiation in sunlight. While we await more definitive data, it is reasonable to recommend an overall "safe sun strategy" in which the use of sunscreens certainly must be accompanied by other protective measures of overall reduction of sunlight exposure.

Basal Cell Carcinoma↗
PubMed1992

Mechanisms and rates of decay of marine viruses in seawater.

Loss rates and loss processes for viruses in coastal seawater from the Gulf of Mexico were estimated with three different marine bacteriophages. Decay rates in the absence of sunlight ranged from 0.009 to 0.028 h, with different viruses decaying at different rates. In part, decay was attributed to adsorption by heat-labile particles, since viruses did not decay or decayed very slowly in seawater filtered through a 0.2-mum-pore-size filter (0.2-mum-filtered seawater) and in autoclaved or ultracentrifuged seawater but continued to decay in cyanide-treated seawater. Cyanide did cause decay rates to decrease, however, indicating that biological processes were also involved. The observations that decay rates were often greatly reduced in 0.8- or 1.0-mum-filtered seawater, whereas bacterial numbers were not, suggested that most bacteria were not responsible for the decay. Decay rates were also reduced in 3-mum-filtered or cycloheximide-treated seawater but not in 8-mum-filtered seawater, implying that flagellates consumed viruses. Viruses added to flagellate cultures decayed at 0.15 h, corresponding to 3.3 viruses ingested flagellate h. Infectivity was very sensitive to solar radiation and, in full sunlight, decay rates were 0.4 to 0.8 h. Even when UV-B radiation was blocked, rates were as high as 0.17 h. Calculations suggest that in clear oceanic waters exposed to full sunlight, most of the virus decay, averaged over a depth of 200 m, would be attributable to solar radiation. When decay rates were averaged over 24 h for a 10-m coastal water column, loss rates of infectivity attributable to sunlight were similar to those resulting from all other processes combined. Consequently, there should be a strong diel signal in the concentration of infectious viruses. In addition, since sunlight destroys infectivity more quickly than virus particles, a large proportion of the viruses in seawater is probably not infective.

Journal Article↗
PubMed2000

Assessment of microencapsulated formulations for improved residual activity of Bacillus thuringiensis.

Bacillus thuringiensis Berliner is a highly efficacious bioinsecticide used to control lepidopteran pests in the field. Unfortunately, it has limited residual activity on plants because sunlight inactivates spores and crystals and they can be washed off by rain. To minimize loss of activity, formulations must contain UV protectants, stickers, or both. We tested approximately 80 formulations and determined optimal combinations of ingredients and spray drying conditions for improving B. thuringiensis residual activity after simulated rain and simulated sunlight. B. thuringiensis stability, after simulated sunlight (xenon light/8 h) and rain (5 cm/50 min), was improved using formulations based on lignin, corn flours, or both, with up to 20% of the active ingredient, when compared with technical powder or Dipel 2x in laboratory assays. Two formulations, made with corn flours or lignin + pregelatinized corn flour (PCF), killed 51.6 and 75.3% of Ostrinia nubilalis (Hübner) neonates after rain, respectively, versus 27% for technical powder. When the insecticidal activity was tested after simulated sunlight, corn flour-based formulations killed 78.5% of test larvae, and the lignin + PCF formulation killed 70.4%, in contrast to technical powder which caused an average of 29% mortality. Formulations made with Dipel 2x rather than technical powder, caused 62.5% mortality (corn flour-based formulations), and 72.3% mortality (lignin + PCF), versus 53.4% for Dipel 2x after rain. When tested after simulated sunlight, formulations killed 95% of the larvae (average of both formulations) versus 82% for Dipel 2x. In a field test, formulations were applied to cabbage and insecticidal activity was determined against Trichoplusia ni (Hübner) neonates exposed to treated leaves. Insecticidal activity of the corn flour-based formulations was comparable to Dipel 2x for 4 d after treatment, but was significantly better than Dipel 2x 7 d after application. A lignin and PCF-based formulation showed significantly higher residual activity than Dipel 2x, 4 and 7 d after application.

Animals↗
PubMedDate not supplied

Photoprotection and prevention of melanoma.

This article summarizes the current position on primary prevention of melanoma, including what is the evidence relating sunlight exposure to the development of melanoma, what forms of photoprotection there are and what are their relative values. There have been increasing incidence and mortality rates due to melanoma in most countries where they are being recorded. The initial approach in many countries has been to develop some form of early detection program in an attempt to diagnose and treat at a curable stage the melanomas that are occurring now. Primary prevention of melanoma is the more long term approach to the problem which many countries are now considering and a number are actively pursuing. Recent concern about stratospheric ozone depletion has contributed to the desire for the primary prevention approach. There are epidemiological data associating the risk of melanoma with increased exposure to sunlight in people with fair skin. They show that it is sunlight exposure in childhood and in doses sufficient to cause sunburn remembered many years later, that is particularly associated with risk of melanoma in adulthood. The exact spectrum of radiation in sunlight which is responsible for these tumours is not known, although the ultraviolet range is believed to be most important, particularly UVB but probably also UVA. The approach to photoprotection is a reduction in the overall exposure to sunlight, not just a single component of it. The natural protection of shade, clothing and hats is promoted as the best protection. Sunscreens have assumed a major component of primary prevention programs based on their convenience of use and also on their widespread promotion by those people who have a commercial interest in them. These products protect predominantly in the UVB range for which there is a sun protection factor (SPF) grading, as well as having some activity in the UVA range (for which there is not yet a satisfactory grading method).

Humans↗
PubMed1992

[Ecologic ultraviolet--a real mutagenic factor for vegetative cells of Bacillus subtilis].

The frequency of leu----Leu+ reversions represented mainly by suppressor mutations is increased in Bacillus subtilis uvr+ and uvr-1 cells after exposure to natural sunlight. Dependence of mutation yield on the time of exposure is linear (one hit kinetics) in case of the uvr-1 strain. In the uvr+ cells the yield of mutations is also linear, but only at short times of exposure, the curve bending and levelling off the plateau after 10-min cell illumination. It has been established in the experiments with optical filters that the mutagenic effect is related to wavelengths which correspond to the UVB zone of ecological UV. The mutagenesis caused by sunlight can be modified (weakened) by some post-irradiation treatments of bacteria, which also led to a decrease of mutations frequencies in B. subtilis uvr+ and uvr-1 cells after exposure to 254-nm UV. The data indicate that: 1) mutagenic influence of sunlight can be overcome only by the joint action of activities of the two cellular repair systems--photoreactivation and excision repair, 2) the real mutagenic effect of sunlight on such a non-photoreactivating organism as B. subtilis would not be enhanced with the increase of the UVB flow in sunlight spectrum.

Bacillus subtilis↗
PubMed1976

[Polymorphic light dermatitis. Photobiology and photoprotection].

It is possible in the majority of patients with polymorphic light eruption to produce lesions experimentally. Only the reproduction of the clinical reaction is significant for the diagnosis. Irradiation is carried out in the same test area two or three times with a dose of up to eight times the minimal erythema dose. Sunlight is the best agent for the evaluation of this protocutaneous disorder. A localised area of the skin can be exposed to midday sunshine about half an hour on three consecutive days. But sunlight has the disadvantage of having a variable ultraviolet emission at different times. It is necessary to differentiate lupus erythematosus and photocontact dermatitis, which may produce identical reactions. Other light sources are the hot quartz lamp, fluorescent tube "sun lamp", solar simulator and the monochromater. Patients with polymorphic light eruption are sensitive to light in the range 300 to 320 nm. but some of them are sensitive to savelengths shorter or longer than this range. The methods of protection against solar radiation which have been tried include: 1) Avoidance of sunlight; 2) Promotion of melanin hyperpgimentation and thickening of the stratum corneum-by controlled exposure to sunlight; 3) Application of a film of a chemical compound that will act as a physical screen and absorb, scatter or reflect damaging radiation; 4) Chemical modification of the stratum corneum by topically applied substances which can conjugate chemically or be absorbed onto the stratum corneum and filter the damaging rays. Many authors at present consider the use of alcoholic solutions of para-aminobenzoic acid (PABA) to be the most effective method of preventing reactions from exposure to sunlight. Pathak and Fitzpatrick showed that 5 % PABA in 70 % ethanol and 2,5 % Escalol 506 in 65 % ethanol is the most effective sunscreen against radiation of the sunburn spectrum. A dihydroxyacetone (DHA) and naphthaquinone (lawsone) sunscreen provides photoprotection for all types of photosensitivity throughout the whole UV spectrum even into the visible region. Systemic photoprotection: The administration of beta-carotene to patients with erythropoietic protoporphyria has resulted in amelioriation of their photosensitivity. Antimalarials are valuable therapeutic agents and are highly effective in controlling cutaneous lupus erythematosus, polymorphic light eruption and occasionally solar urticaria.

Drug Evaluation↗
PubMed1988

Vitamin D--soltriol the heliogenic steroid hormone: somatotrophic activator and modulator. Discoveries from histochemical studies lead to new concepts.

Evidence from autoradiographic studies with 3H 1,25(OH)2 vitamin D3 (soltriol) about its many sites of nuclear binding and multiple actions suggests that the traditional view of "vitamin D and calcium" is too limited and requires modification. A new concept has been developed which proposes that the skin-derived hormone of sunshine, soltriol, is a somatotrophic activator and modulator that affects all vital systems. Regulation of calcium homeostasis is only one of its many actions. Target tissues for soltriol include not only bone, intestine and kidney, but also brain, spinal cord, pituitary, thyroid, endocrine pancreas, adrenal medulla, enteroendocrine cells, thymus, and male and female reproductive organs. Accordingly, actions of soltriol involve effects on autonomic and endocrine regulation with changes in tissue and blood hormone levels, innervation of skeletal muscle, immune and stress response, digestion, blood formation, fertility, pregnancy and lactation, general energy metabolism, mental processes and mood, and others. The skin-mediated transduction of short-wave sunlight induces a purposeful modulation of growth, reproduction and other biological activities in tune with the conditions of the sun cycle and season. Synthesis and actions of vitamin D3-soltriol are dependent not only on the amount of sunlight, but also on the availability of precursor in the skin and access of sunlight, the rate of hydroxylation in liver and kidney, and the modulation of these events by the endocrine status, in particular growth and reproduction. A concept of a five-level control of soltriol synthesis is proposed, in which the hydroxylation steps provide for a sensitive tuning. Relationships between the heliogenic skin-derived hormonal system and the helioprivic pineal-derived hormonal system are recognized and a comprehensive concept of the "endocrinology of sunlight and darkness" is pointed out.

Calcitriol↗
PubMed2004

Photodegradation of polychlorinated dibenzo-p-dioxins and dibenzofurans in soil with vegetable oil.

GOAL, SCOPE AND BACKGROUND: This study was carried out to investigate the effect of olive oil on the photodegradation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in contaminated sawmill soil. Previous studies had shown that the solubility of PCDD/Fs in olive oil is high and a rapid photodegradation of PCDD/Fs takes place in olive oil when irradiated with ultraviolet (blacklight) lamps. The efficiency of this treatment method was evaluated under more practical conditions. These included the use of sunlight irradiation and a lower-grade olive oil, without a preliminary extraction of soil with olive oil. METHODS: A 1-cm layer of contaminated sawmill soil was blended with 20 weight-% of olive oil and exposed to sunlight for four weeks. In another experiment, a new dose of olive oil was added at the middle of the exposure period. The PCDD/F concentrations of the soils were monitored periodically. RESULTS AND DISCUSSION: A reduction in the concentration of 2,3,7,8-chlorinated PCDD/Fs by 59% and in WHO-TEQ in contaminated sawmill soil by 48% was attained after blending the soil with two doses (20 + 20%) of olive oil and exposing the mixture to sunlight for four weeks. Photodegradation with only one dose of olive oil was less efficient. This suggests that periodical additions of olive oil would be needed to maintain a proper degradation rate. After the oil additions, the WHO-TEQ content of the soil declined with first order reaction half-lives of 19.2 to 19.7 d. The overall half-life during the four-week treatment, however, was 30 d. CONCLUSION: A significant reduction in the PCDD/F concentration of aged sawmill soil can be achieved with a relatively simple olive oil-sunlight treatment. RECOMMENDATIONS AND OUTLOOK: Some theoretical and technological questions need to be solved before using the investigated soil decontamination method in larger-scale applications. The functions of vegetable oils in photodegradation processes should be studied in more detail. The amount of oil that is needed for a proper solubilisation and photodegradation of PCDD/Fs should be minimised. Moreover, special care should be taken to prevent mobilisation of PCDD/Fs to the surrounding environment and to avoid leaving bioavailable residuals of PCDD/Fs in soil.

Benzofurans↗