Ultraviolet radiation regulates cortisol activity in a waveband-dependent manner in human skin ex vivo.

BACKGROUND: 11ß-Hydroxysteroid dehydrogenase type 1 (11ß-HSD1), 11ß-hydroxysteroid dehydrogenase type 2 (11ß-HSD2), and glucocorticoids (GC) and their receptor (GR) play a key role in tissue-specific regulation of GC action. OBJECTIVES: To determine the expression of genes encoding 11ß-HSD1 (HSD11B1), 11ß-HSD2 (HSD11B2) and GR (GRα; also known as NC3R1) and their protein products, and levels of cortisol in human skin explants and/or cocultured keratinocytes/melanocytes after treatment with ultraviolet (UV) A, B or C wavebands. METHODS: Skin from foreskins and/or cocultured human keratinocytes/melanocytes were irradiated with UVA, UVB or UVC (skin) and incubated for 12 and 24 h. Methods of reverse transcription-polymerase chain reaction, Western blotting, enzyme-linked immunosorbent assay and immunohistochemistry (IHC) were used to determine expression and localization of corresponding genes or antigens. RESULTS: UVB enhanced the HSD11B1 gene and protein expression in a dose-dependent manner, while UVA had no effect. Similarly, UVC increased 11ß-HSD1 protein product as measured by IHC. UVB and UVC enhanced cortisol production and decreased epidermal GR expression, while UVA had no detectable effects. Although both UVA and UVB stimulated HSD11B2 gene expression, only UVA increased 11ß-HSD2 protein product levels with UVB and UVC having no effect. CONCLUSIONS: We suggest that these differential, waveband-dependent effects of UV radiation on the expression of cutaneous HSD11B1, HSD11B2 and GRα genes and their corresponding protein products, and cortisol production are to protect and/or restore the epidermal barrier homeostasis against disruption caused by the elevated cortisol level induced by UVB and UVC.

Reintroduction of a classic vitamin D ultraviolet source.

As early as 1930 sunlamps claiming to provide ultraviolet (UV) exposure to make vitamin D were sold to the public in the US and Canada for home use. Today even with dietary supplementation of vitamin D many people do not get enough solar UV exposure to maintain sufficient vitamin D levels. There is growing interest in the availability of sunlamps for this purpose. The original Sperti Sunlamp, with label claiming vitamin D benefit was approved by the American Medical Association in 1940 as a sunlamp. This intermediate pressure mercury lamps ultraviolet B emission lines, at 297, 302, and 313 nm are able to convert 7-dehydrocholesterol in the skin to vitamin pre-D3 initiating the natural process of vitamin D formation. Today's KBD Vitamin D lamp, an updated model of the earlier type source. In order to comply with modern safety guidance, the source is filtered to remove unnecessary UVC radiation and is equipped with a timer to control the dose administered. The 5 min timer provides an exposure, at 20 in. from the user's skin, of one standard erythemal dose (SED). The SED represents a suberythemal dose for even the most sensitive skin type I individual.

In vivo formation of Maillard reaction free radicals in mouse skin.

The Maillard browning reaction between carbohydrates and amines is part of an extensive series of reactions that is the basis for the brown color caused by the "sunless tanning" agent dihydroxyacetone in self-tanning products. The initial stages of the reaction are quite complex, but the ultimate products are brown polymers known collectively as melanoidins. We have now used electron spin resonance to show that radicals are produced in vivo by the Maillard reaction, initiated by treating the skin of hairless mice with a solution of dihydroxyacetone in buffer. Dihydroxyacetone was used as the carbohydrate because it is simple but highly reactive and is the only USFDA approved color additive for the production of a sunless tanning response on skin. Treated skin turned brown within 24 h and showed an electron spin resonance signal after sacrifice of the animal. The control sample, consisting of untreated skin from the same animal, remained its original pink color and had no electron spin resonance signal. In corresponding ex vivo experiments in which mouse skin was soaked in dihydroxyacetone solutions, it was conclusively demonstrated that the presence of the dihydroxyacetone was required for radical formation in skin. In both the in vivo and ex vivo reactions the electron spin resonance signal consists of a broad single line with a peak-to-peak linewidth of 15 Gauss and a g value of 2.0035. We suggest that dihydroxyacetone interacts on skin through a free radical mediated reaction similar to its in vitro reactions with amines and amino acids.

Changes in epidermal forward scattering absorption after UVA or UVA-UVB irradiation.

Groups of skh-1 (albino) and Skh-2 (pigmented) hairless mice were irradiated for 125 hr using a modified GE F8T5-BL black light with and without a 3-mm plate glass filter to remove light below 320 nm. The epidermis was examined by forward scattering and by histological section postirradiation at 48 hr, 96 hr, 9 days, and 23 days. Changes in the epidermis of all animals were compared to control groups. Although no differences were seen between Skh-1 and Skh-2 mice, both the magnitude and shape of the forward scattering absorption curves were changed by the irradiation used. In both strains, differences which were detected at 48 hr postirradiation had returned to normal visually by 23 days, with no augmented pigmentation occurring in Skh-2 animals. At 23 days postirradiation, however, residual optical alterations were observed. This phenomenon, detected optically, may be skin acclimatization.

Pasteuria nishizawae sp. nov., a mycelial and endospore-forming bacterium parasitic on cyst nematodes of genera Heterodera and Globodera.

This study describes Pasteuria nishizawae sp. nov., a fourth species of the genus Pasteuria. This mycelial and endospore-forming bacterium parasitizes the adult females of cyst-forming nematodes in the genera Heterodera and Globodera. The distinct ultrastructural features and unique host range found for this bacterium separate it from two closely related species, Pasteuria penetrans, which parasitizes several species of root-knot nematodes of the genus Meloidogyne, and Pasteuria thornei, which appears to parasitize only one species of the root-lesion nematode, Pratylenchus brachyurus. Because these obligate bacterial parasites of nematodes have not been cultured axenically, the taxonomic relationships described here for each species are based mainly on developmental morphology, fine structure of the respective sporangia and endospores, and their pathogenicity on nematode species.

The correlation of indoor solar simulator and natural sunlight: testing of a sunscreen preparation.

To determine the equivalence of xenon arc solar simulator and natural sunlight test results, the sun protection factor (SPF) for an experimental sunscreen preparation was determined using each light source. The minimal erythemal doses (MEDs) were shown to be equivalent on unprotected skin. It was necessary to supply additional heat to the treated skin prior to solar simulator exposures to obtain comparable SPFs. By careful control of the subjects' environment, natural sunlight effects can be duplicated with a solar simulator.

Performance of six sunscreen formulations on human skin: a comparison.

Indoor and outdoor tests were performed on human volunteers to determine the protection offered by six commercially available products containing single sunscreen ingredients and combinations of ingredients. Indoor solar simulator studies were performed to determine the inherent efficacy of each product, including use of a whirlpool treatment to evaluate the resistance of each product to wash off. The outdoor study included a ten-minute swimming period followed by sunlight exposure. In all tests, the combination of 7% octyl-dimethyl p-aminobenzoic acid ester and 3% oxybenzone was substantially more effective in protecting against sunburn than any other formula tested, including 5% p-aminobenzoic acid (PABA).

An action spectrum for ultraviolet induced elastosis in hairless mice: quantification of elastosis by image analysis.

To determine an action spectrum for ultraviolet (UV)-induced elastosis, four groups of 24 albino hairless mice each were exposed to four different spectra emitted by a xenon arc solar simulator fitted with cut-off filters (Schott WG 320, 335, 345, and 360). These filters progressively removed more of the shorter wavelengths until, in the final spectrum, only long wavelength UVA (greater than 335 nm) remained. Exposures continued up to 62 weeks. A fifth group of mice served as controls. Skin biopsies were taken at pre-determined dose points and were processed for light microscopy. Elastosis was quantified by computerized image analysis, yielding dose-response curves for each spectrum. The total energy required for a 50% increase in elastic tissue compared to controls was determined graphically for each spectrum. These were: WG 320, 65 J/cm2; WG 335, 865 J/cm2; WG 345, 1230 J/cm2; and WG 360, 2000 J/cm2. Our results were tested against published action spectra for erythema, photocarcinogenesis and elastosis. The erythema spectrum was the most predictive for elastosis except that the longer UVA wavelengths were less effective for elastosis than for erythema. Solar simulating radiation (WG 320 filter) with its UVB component was the most effective in inducing elastosis. Full spectrum UVA (WG 345) required 20 times more energy while long wavelength UVA (WG 360) required 30 times more energy to induce equivalent elastosis.

Discrepancies in the measurement of spectral sources.

Comparison of spectroradiometric and meter measurements of a series of ultraviolet radiation sources indicates that a wide divergence between readings can occur. We found that with a xenon arc filtered as a solar simulator producing UV-A (320-400 nm) and UV-B (290-320 nm) radiation, the meter can either over- or underestimate the emission of the source when different cut-off filters are used. The most severe the UV-B meter reading, although the UV-A reading can also reading can reading can also be problematic. Meters should be calibrated used to measure.

In vitro and in vivo ultraviolet-induced alterations of oxy- and deoxyhemoglobin.

Ultraviolet (UV) radiation was found to convert oxyhemoglobin and deoxyhemoglobin stoichiometrically into methemoglobin and a met-like product, respectively. The peak conversion efficiency for oxyhemoglobin occurred at 285 nm and decreased by a factor of 100 by 315 nm. The peak conversion efficiency for deoxyhemoglobin occurred at 290 nm and decreased by a factor of 30 by 320 nm. The transformation of oxyhemoglobin to methemoglobin was also documented in intact erythrocytes using UV-B radiation. Finally, similar transformations were found to occur in human skin with UV-B exposure but not on all volunteers tested. These results imply that methemoglobin will be formed in vivo on solar exposure and provide evidence that UV-B photons reach the blood vessels.

Dose-response of chronic ultraviolet exposure on epidermal forward scattering-absorption in SK-1 hairless mouse skin.

This work provides a dose-response model of UV-induced epidermal-stratum corneum thickening induced by irradiation at wavelength lambda. This model assumes that photobiochemical reaction(s) can give rise to hyperplasia in a manner which is predictable from a simple photochemical kinetic scheme. In this work, we derive an equation which predicts an approximately linear relationship between the logarithm of the increase in optical skin thickening measured at 320 nm (delta OD320) and total cumulative dose (DT) seen by the target cells in or near the basal layer. For each excitation wavelength lambda, the slope R(lambda) of the log delta OD320 vs DT plot is proportional to epsilon(lambda) phi rx, where epsilon(lambda) is the extinction coefficient for the target chromophore at excitation wavelength, and phi rx is the quantum yield for the photochemical reaction(s) leading to hyperplasia. Our data previously obtained from irradiation of SK-1 hairless mice with "monochromatic" UV wavebands at 280, 290, 300, 307 and 313 nm (Menter et al., 1988, Photochem. Photobiol. 47, 225-260.) and data from Sterenborg and van der Leun at 254 and 313 nm (1988, Photodermatology 5, 71-82) are in good agreement with this model, except for 254 and 280 nm excitation, which are greatly attenuated by epidermis-stratum corneum. For excitation at the latter wavelengths, "dark" regressive processes successfully compete with the "light" reaction(s) which lead to (pre)cancerous lesion. This difficulty notwithstanding, the "intrinsic" action spectrum for hyperplasia derived from these measurements indicates that the target chromophore preferentially absorbs in the UV-C region.(ABSTRACT TRUNCATED AT 250 WORDS)

A multitherapy resistance factor from melanoma reveals that killing by near UV is different from genotoxic agents.

A diffusible multitherapy resistance factor (MTRF) is produced by Cloudman S91 melanoma cells in vitro. The MTRF decreases sensitivity of the target cell line, S91/amel, to gamma-irradiation, UVC (200-280 nm) and mitomycin C (MMC). In the present study, we demonstrate that MTRF also increases the survival of S91/amel after exposure to actinomycin D (AMD) and vinblastine (VBL). The MTRF is thus effective when target cells have been exposed to five genotoxic agents that act by different mechanisms. It does not alter the response to the same five agents of the S91/I3 producer cells, which are presumably saturated with the factor. The factor has no effect on the survival of S91/amel cells that have been exposed to lethal doses of near monochromatic UVB (280-320 nm) or UVA (320-400 nm) or to polychromatic FS20 lamps. The lack of effectiveness of MTRF after cells have been exposed to near (300-400 nm) UV radiation indicates that in this wavelength range, S91 melanoma cells are killed by mechanisms that are different from the lethal effects of the five genotoxic agents (gamma-irradiation, UVC, MMC, AMD and VBL) to which the target cells demonstrate a response.

Beta-carotene does not act as an optical filter in skin.

Beta-carotene, when orally administered, only slightly increases the sunburn threshold in normal humans but effectively diminishes sunlight risk in patients suffering from erythropoietic protoporphyria. In addition, beta-carotene has been shown to inhibit UV-induced carcinogenesis in mice when administered either orally or intraperitoneally. To examine the photoprotective properties of beta-carotene, SKH-HR1 albino hairless mice received beta-carotene supplemented diets for either two or four weeks. At the end of each treatment period the skins were visibly yellow. Whole skin and epidermis from each animal were studied by forward scattering transmission spectroscopy and compared with age-matched controls. While no major optical differences were seen in the whole skin or in the epidermis, the presence of beta-carotene was optically demonstrated by weak but typical beta-carotene absorption peaks in the epidermis following the two week feeding period. The peaks were also apparent in the four week group. However, the beta-carotene peaks could not be resolved through full thickness skin. Despite the yellow appearance of the skin, the absorbance due to the carotene was insufficient to impart significant photoprotection. These results confirm previous theoretical arguments that oral beta-carotene treatment does not attain a sufficient concentration in the skin to produce a typical sunscreen effect by absorption of radiation. When beta-carotene is effective in the treatment of photosensitivity, it must produce its protectiveness through an alternative mechanism.

Photoprotection by melanin.

This paper is an attempt to summarize the current state of information on melanin and epidermal melanin pigmentation (EMP) as photoprotective agents. The chemistry and biochemistry of melanin (the particle) and its interaction, in its various forms, with UV radiation are considered. Methods of attenuation of UV radiation are discussed in terms of structure and chemical constituents. Photoprotection by constitutive and facultative pigmentation is reviewed with minimum erythema dose (MED) as the end point. The issue of acclimatization to UV radiation is discussed in terms of UVB phototherapy for psoriasis. Finally, skin cancer is considered as an end point and the reduction of its incidence with pigment level is discussed. It is concluded that whilst EMP provides protection, its extent depends on the end point chosen for evaluation. MED is a convenient photobiological end point but is rather insensitive, whereas skin cancer is sensitive but impractical for laboratory studies. Our current state of knowledge of melanin lacks information on its absorption and scattering coefficients and its refractive index. Methods for the quantitative measurement of EMP are also urgently required.

UV protection by clothing: an intercomparison of measurements and methods.

In an attempt to reduce the incidence of skin cancer, cancer foundations have run educational campaigns which encourage the general population to limit their solar UVR exposures. An important part of these campaigns, in particular in Australia, but also more recently in Europe and the U.S., has been the adoption of protective measures such as sunscreens, hats, sunglasses and clothing. The protective properties of fabrics and clothing against ultraviolet radiation (UVR) have been known for some time, but recently there has been considerable interest in quantifying the degree of protection. This has been generated, in part, by the requirements for occupational protection for outdoor workers as well as the provision of UVR protection for the recreational market. The quantification of UVR protection has been laboratory based using in vitro test methods. Development of a standard test method has become an important part of the testing process, and this paper presents results from an intercomparison involving five independent testing laboratories. Agreement is good, in particular for samples with protection factors below 50. Technical difficulties and sources of errors associated with the measurements are discussed.

Biocontrol: Bacillus penetrans and Related Parasites of Nematodes.

Bacillus penetrans Mankau, 1975, previously described as Duboscqia penetrans Thorne 1940, is a candidate agent for biocontrol of nematodes. This review considers the life stages of this bacterium: vegetative growth phase, colony fragmentation, sporogenesis, soil phase, spore attachment, and penetration into larvae of root-knot nematodes. The morphology of the microthallus colonies and the unusual external features of the spore are discussed. Taxonomic affinities with the actinomycetes, particularly with the genus Pasteuria, are considered. Also discussed are other soil bacterial species that are potential biocontrol agents. Products of their bacterial fermentation in soil are toxic to nematodes, making them effective biocontrol agents.

Theratromyxa weberi, An Amoeba Predatory on Plant-Parasitic Nematodes.

Theratromyxa weberi, an amoeba, was isolated and cultured in the laboratory to determine the physical conditions that influence its predation on plant parasitic nematodes. In greenhouse tests, the amoeba was a poor biological control agent of the root-knot nematode, Meloidogyne incognita.

Freezing and Storing Ditylenchus dipsaci in Liquid Nitrogen.

After 18 months of storage at -150 C, some larvae of Ditylenchus dipsaci, which had been treated in a 7.5% solution of dimethyl sulphoxide and cooled to -25 C before storage, were still viable on thawing. Some survivors penetrated and developed normally in stems of alfalfa seedlings. Tests showed that active larvae could be frozen directly, thus eliminating the need to use the quiescent stage of this nematode previously thought necessary for successful storage at cryogenic temperatures. The method described is suitable for long-term storage of D. dipsaci and may, with slight modifications, be used to preserve other plant-parasitic nematodes.

Use of low temperature scanning electron microscopy to observe frozen hydrated specimens of nematodes.

Frozen hydrated specimens of Pratylenchus agilis and dauer larvae of Steinernema carpocapsae were observed with low-temperature field emission scanning electron microscopy. This new technique provides information about the surface features of nematodes and also allows specimens to be fractured to reveal their internal structure. Furthermore, both halves of fractured specimens can be retained, examined, and photographed either as two-dimensional micrographs or as three-dimensional images for stereo observation (stereology) or quantitative measurements (stereometry). This technique avoids artifacts normally associated with procedures required to prepare nematodes for examination in the transmission and scanning electron microscopes, such as chemical fixation, dehydration, and sectioning or critical point drying.

Benomyl Tolerance of Ten Fungi Antagonistic to Plant-parasitic Nematodes.

Ten strains of fungi were tested for tolerance to the fungicide benomyl. Verticillium chlamydosporium strain 2 did not grow in the presence of benomyl; Drechraeria coniospora strains 1 and 2 and Chaetomium sp. tolerated only 0.1 mug benomyl/ml medium; Acremonium bacillisporum, an unidentified fungus, and Phoma chrysanthemicola uniformly grew at 1 mug/ml, but some hyphae grew at higher benomyl concentrations; Fusarium sp. tolerated 475 mug/ml, but some hyphae grew on medium amended with 1,000 mug/ml; Verticillium lecanii and V. chlamydosporium strain 1 routinely tolerated 1,000 mug/ml. Fungi generally grew more slowly at higher than at lower benomyl concentrations. Strains with elevated tolerance to benomyl were selected from Acremonium bacillisporum, Drechmeria coniospora, Fusarium sp., and an unidentified fungus. These strains retained the increased tolerance after repeated transfers on unamended medium.