Ultraviolet Component Research Articles

Activation of mammalian gene expression by the UV component of sunlight--from models to reality.

Ultraviolet radiation activates the expression of a wide variety of genes, by pathways which differ between the short non-solar ultraviolet C (UVC) wavelengths, which are strongly absorbed by nucleic acids, and the long solar ultraviolet A (UVA, 320-380 nm) wavelengths, which generate active oxygen intermediates. Intermediate solar ultraviolet (UV) wavelengths in the UVB (290-320 nm) range also contain an oxidative component, but more closely resemble UVC in their gene activating properties. Short wavelength UV, in common with other extracellular stimuli including growth factors, activates signal transduction events that involve both stress- and mitogen-activated protein kinase cascades. The extrapolation of the complex modulation of gene expression that ensues to the consequences of natural UV exposure requires careful attention to the details of doses and wavelength employed in the model experiments. Nevertheless, there is evidence that UVB irradiation of skin can activate the expression of proteins including immunomodulating cytokines, ornithine decarboxylase and, to a limited extent, nuclear oncogene products, as well as lead to stabilisation of p53. Non-cytotoxic doses of UVA radiation also lead to the strong activation of several genes which would be expected to have functional relevance in vivo.

Moths: Myths and mysteries of stress resistance

AbstractA cabbage looper's job, in many respects not unlike our own, is to survive its early developmental period and grow up healthy, metamorphose into an adult moth, and beget the next generation of loopers. Given its numerous predators, exposure to the continuous barrage of toxic physical, chemical and biological agents delivered by humans in an effort to eradicate it, as well as nature's own hazards, such as the ultraviolet component of sunlight and hazardous natural chemicals in plants that serve to deter ingestion by the looper, it is not difficult to view the looper as a highly stressed organism. However, the looper and its lepidopteran ancestors have been quite successful at resisting such hazards since the Mesozoic Era. The purpose of this brief review will be to examine some of the potential mechanisms by which the looper and its relatives have been able to be so successful over these past 200 million years.

Radioluminescent dosimetry of α-quartz

The variation in the ultraviolet component of the radioluminescence intensity during X-ray excitation of α-quartz has been found to be dependent on the dose of previous ionizing irradiation. A new method of radiation dosimetry using UV radioluminescence is described. Radioluminescent dosimetry measurements of γ-rays produced by Chernobyl accident and background irradiation were made using natural and extracted crystalline quartz.

Short-lived charge-transfer-to-solvent-states and multiple electronic relaxations following femtosecond excitation of aqueous chloride ion

Abstract Early charge transfer processes triggered by the photoexcitation of an aqueous sodium chloride solution (molar ratio H 2 O/NaCl = 55) at 294 K have been investigated by using femtosecond absorption UV-IR spectroscopy. The initial UV energy deposition proceeding by one- (4 eV) and/or two-photon (2 × 4 eV) absorption results in the formation of multiple short-lived electronic states which have been discriminated within the spectral range 360–1250 nm (3.44-0.99 eV). Two well-separated spectral signatures involving UV and infrared transitions have been discriminated and assigned to different excited CTTS states (charge transfer to solvent) as recently suggested by quantum simulations of an aqueous halide I − [Sheu and Rossky, Chem. Phys. Letters 202 (1993) 186; 213 (1993) 233]. A short-lived ultraviolet component appearing within the UV pump pulse and exhibiting a monoexponential relaxation time of 190 ± 20 fs would correspond to a lo excited CTTS state of the chloride ion (CTTS ∗ ). The other ultrashort-lived band peaking above 0.99 eV (1250 nm) and characterized by a high deactivation rate (≈2 × 10 13 s −1 ) is tentatively assigned to a high excited CTTS state (CTTS ∗∗ ) triggered by a two-photon absorption process (8 eV). This transient state precedes the ap pearance of a well-defined infrared component peaking around 1250 nm and due to the (p-like) excited hydrated electron (e prehyd − ). The relaxation of this infrared electron occurs with a time constant of 300 fs and leads to the formation of the ground state of the hydrated electron (e hyd − ). Near-infrared spectroscopic investigations performed in the energy range 1.51-1.24 eV (820–1000 nm) have permitted to clearly identify the existence of additional absorption bands peaking around 880 nm. It is the first time that near-infrared bands are directly observed in an aqueous solution of halide ions. These spectral contributions are assigned to inhomogeneous populations of electron-atom pairs ({e − :Cl n H 2 O A,B} ). The involved photochemical channel can compete wit electron hydration channel for which a pre-hydrated state (e prehyd − ) has been identified. The existence of these near-infrared states would be due to local solvent effects which assist or impede an electron localization outside the first hydration shells of the atomic core (Cl). The electronic population absorbing in the near infrared exhibits a dual behavior whose characteristic times are 330 fs ({e − :Cl n H 2 O A} ) and 750 fs (e − : Cl n H 2 O B ) respectivley. The faster relaxation channel due to contribute to the early geminate recombination between the ground state of the hydrated electron and the chlorine atom. The slower deactivation channel (1.29 × 10 12 s −1 ) would be due to an electronic state ({e − :Cl n H f 2 0 B} ) whose interconversion with a ground state of a hydrated electron has been identified in the present study. This electron photodetachment pathway leads to a delayed formation of hydrated electrons (e hyd −′ ) and can be seen as a specific solvent cage effect in the vicinity of the counterion (Na + ). The direct characterization of short-lived semi-ionized states by near-infrared spectroscopy provides new informations on solvent cage effects during ultrafast electron transfer reactions in ionic solutions. These complex photochemical data obtained with aqueous sodium chloride are discussed at the microscopic level considering recent quantum theories on semi-ionized or metastable states in ionic solutions.

Cataract and latitude.

For many years, it has been suggested that exposure to sunlight, particularly its ultraviolet component, may be associated with an increased risk of senile cataract. This paper addresses 1) the physical and geographic variables that affect the entry of ultraviolet light in the eye; 2) the epidemiologic evidence that associates cataract with ultraviolet light exposure; and 3) the effectiveness of personal barrier protection (i.e. sunglasses and hats) in reducing ocular exposure to ultraviolet light. The epidemiologic evidence is drawn from studies in Australia, China, Tibet, and the United States. The U.S. evidence consists of data from the Maryland Watermen study and analyses of cataract surgery under the Medicare program which provides health insurance for nearly all Americans age 65 and over (30 million) and pays for 85% of the 1.3 million cataract extractions performed annually in the U.S. Analysis of the Medicard data shown that, after controlling for age, sex, and race, and income of the population and also controlling for supply of ophthalmologists, optometrists, price of surgery and local practice costs, the strongest predictor of cataract surgery likelihood in a Medicare beneficiary is the person's latitude of residence. Latitude correlates directly with the UV-B content of sunlight, because the incident angle of the sun determines the atmospheric penetration of ultraviolet radiation. Data suggest that the probability of cataract surgery in the U.S. increases by 3% for each 1 degree decrease (i.e. more Southerly) in latitude.

Zinc oxide/n-Si junction solar cells produced by spray-pyrolysis method

Zinc oxide (ZnO)/n-Si junction solar cells were fabricated by a spray-pyrolysis method and high short-circuit photocurrent densities and relatively high photovoltages were obtained by adjusting the conditions of the deposition and the post-deposition heat treatment. Consequently, relatively high conversion efficiencies ranging between 6.9% and 8.5% were obtained. The efficiency of the solar cells with ZnO/n-Si structure decreases slowly with time when they are kept in air in the dark because of the increase in the thickness of the silicon oxide layer between Si and the ZnO film. This degradation can be avoided by forming an indium-tin-oxide (ITO) overlayer on the ZnO film, indicating that the silicon oxide layer grows through the reaction of Si with oxygen diffusing from the atmosphere, not with ZnO. The efficiency of the ZnO/n-Si junction solar cells decreases rapidly with the illumination time. Capacitance-voltage measurements show that this degradation is caused by a decrease in the work function of the ZnO film. The decrease in the work function is caused by desorption of O−2 from the grain boundaries of the ZnO films. When incident light contains no ultraviolet (UV) component, this degradation does not occur, indicating that the desorption is caused by the acceptance of holes generated by UV light.

Simulation of daylight for viewing and measuring color

AbstractFor convenience and reproducibility, daylight is artificially simulated for viewing and measuring colors. Daylight has been standardized in a way that is impractical. the evaluation of fluorescent materials requires simulation of the ultraviolet component of daylight or daylight through a window. Sources for viewing are assessed by spectroradiometry and standard computations. Sources for spectrophotometry may be tested the same way or by measuring radiance factors of fluorescent standards. Better manufacturing methods have improved glass filters. A new filter design method takes account of the spatiospectral nature of the source and affords many degrees of freedom.

Atlas of quasar energy distributions

We present an atlas of the spectral energy distributions (SEDs) of normal, nonblazar, quasars over the whole available range (radio to 10 keV X-rays) of the electromagnetic spectrum. The primary (UVSX) sample includes 47 quasars for which the spectral energy distributions include X-ray spectral indices and UV data. Of these, 29 are radio quiet, and 18 are radio loud. The SEDs are presented both in figures and in tabular form, with additional tabular material published on CD-ROM. Previously unpublished observational data for a second set of quasars excluded from the primary sample are also tabulated. The effects of host galaxy starlight contamination and foreground extinction on the UVSX sample are considered and the sample is used to investigate the range of SED properties. Of course, the properties we derive are influenced strongly by the selection effects induced by quasar discovery techniques. We derive the mean energy distribution (MED) for radio-loud and radio-quiet objects and present the bolometric corrections derived from it. We note, however, that the dispersion about this mean is large (approximately one decade for both the infrared and ultraviolet components when the MED is normalized at the near-infrared inflection). At least part of the dispersion in the ultraviolet may be due to time variability, but this is unlikely to be important in the infrared. The existence of such a large dispersion indicates that the MED reflects only some of the properties of quasars and so should be used only with caution.

Graviperception and motility of three Prorocentrum strains impaired by solar and artificial ultraviolet radiation

The effects of solar and artificial ultraviolet radiation on the motility and graviorientation of three strains of the dinoflagellate Prorocentrum were studied. P. micans isolated from the Baltic Sea shows a pronounced negative gravitaxis which switches to a positive one even after short exposure times to either solar or artificial UV irradiation. In constrast P. minimum strains isolated from the Kattegat and the Atlantic coast off Portugal showed only a weak upward orientation. In all three strains the linear swimming velocity decreases after short exposure times and, in addition, the percentage of motile cells in the populations drastically decreases. Removing the ultraviolet component of solar radiation with a cut-off filter prolongs the tolerated exposure times.

Artificial ultraviolet whole-body radiation does not modify serum lipoprotein, plasma fibrinogen, plasminogen or antithrombin III concentrations in post-myocardial infarction patients

The relationship of ischaemic heart disease (IHD) to seasonal and latitude variation has prompted speculation that exposure to the ultraviolet component of solar radiation may reduce IHD risk. This hypothesis was partially tested by exposing 14 post-myocardial infarction patients to a 6 week course of artificial whole-body ultraviolet radiation (UVR). Serum lipoprotein and plasma coagulation factor concentrations were measured before and after the course of UVR. Results were compared with similar measurements from a placebo-controlled group of 13 post-myocardial patients. Despite a more than two-fold rise in mean serum 25-OHD, serum lipoprotein and plasma fibrinogen, anti-thrombin III and plasminogen concentrations did not change significantly in the UVR group. Significant but minor change in prothrombin time and thrombin time in the placebo group appear unlikely to be of biological significance. Seasonal and latitude variation in these IHD risk factors appear unrelated to corresponding variation in solar UVR exposure.

The QED (Quasar Energy Distributions) Atlas

While the energy distributions of optically and radio selected quasars have the same, reproducible, mean shape in the infrared to ultraviolet region, the strength of the infrared and ultraviolet components can vary by over a decade from object to object.

Optical properties of wavelength shifting panels

This paper describes the determination of the optical properties of the Bicron wavelength shifting acrylic plastic (BC-480) that absorbs ultraviolet radiation and then reemit it in the visible part of the spectrum. The refractive index and the attenuation coefficient as a function of wavelength were determined from transmission and reflection data. The reemitted visible spectrum was accurately measured using an optical multichannel analyzer and the quantum efficiency of the photoluminescence (the ratio between the number of emitted photons to the absorbed photons) was determined at different wavelengths in the ultraviolet. Finally, these results are applied to determine the effectiveness of this wavelength shifting panel as a means of detecting the ultraviolet component of the Cherenkov spectrum produced by a relativistic particle in water.

Net total and UV-B radiation at the sea surface

A three-week continuous record from 21 September to 5 October 1988 of solar and terrestrial downward and upward radiation flux densities (1 data set per minute) obtained during the Atlantic Ocean cruise of the R/V Polarstern (ANT VII/1) along 30° W between 30° N and 30° S is evaluated. As the cruise crossed both subtropics and tropics of the Atlantic Ocean, characteristic daily cycles and meridional distributions of the radiation components and atmospheric turbidity were obtained. Special attention is given to the ultraviolet component of global radiation. The influence of cloudiness on the radiation quantities is discussed. As the knowledge of the spatial and temporal distribution of solar and longwave atmospheric radiation at the sea surface is important for numerous meteorological, oceanographic, and physico-chemical investigations, this data set is compared with other measurements of the cruise. This work is the continuation of the measurements made during the cruise ANT V/5 of R/V Polarstern along 30° W between 40° S and 40° N in March/April 1987.

Topical retinoic acid augments ultraviolet light-induced melanogenesis.

Melanin, the natural pigment found in human skin, absorbs and protects against the ultraviolet (UV) components of sunlight. Melanin production (melanogenesis) is increased by exposure to sunlight, causing a darker skin colour which is regarded as aesthetically pleasing by many humans, who therefore expose themselves to large amounts of potentially damaging sunlight. We have found that topically applied all-trans retinoic acid, a metabolic derivative of vitamin A, greatly enhances UV light-induced melanogenesis: the same preparation on its own had no effect on skin pigmentation. An orally administered retinoid, temarotene, did not have this effect. These observations were made using a lightly pigmented mouse strain, HRA: Skh-2, and confirmed in 2 human volunteers. This is the first time that metabolic derivatives of vitamin A have been shown to augment UV light-induced melanogenesis, suggesting a role for vitamin A in this process.

Application of Glow Curve Analysis Methods to Improve TLD-100 Dose Reassessment Performance

This paper presents a method of improving the TLD-100 dose reassessment performance. This method consists of applying numerical analysis techniques for evaluating the TLD-100 phototransferred thermoluminescence (PTTL) glow curve. From this analysis, a simple procedure for estimating the ultraviolet background components usually present in phototransferred thermoluminescence (TL) signals has been established. This procedure has been implemented in a computer program which performs the automatic evaluation of the glow curves and extracts the dose information contained in the PTTL curves. The use of this computer-aided evaluational method has enabled the extension of the working range of estimated absorbed dose down to 0.2-0.5 mGy with very adequate operational quality for doses even below the conventionally admitted lower reestimation limit (approximately 2 mGy). Because TL readout is a destructive process, the ability to reestimate doses can be important in any kind of dosimetric activity, such as operational dosimetry programs. The other commonly used dosimeter, film, uses a nondestructive readout and, therefore, presents some advantages over TLD when dose reassessment is necessary. With the reported improvements in the TLD-100 dose reassessment performance, the full range of absorbed doses covered by film dosimetry can now be reliably reassessed using TLD-100 dosimeters.

The steroid hormone of sunlight soltriol (vitamin D) as a seasonal regulator of biological activities and photoperiodic rhythms

Neural and systemic somatotrophic effects of the ultraviolet component of sunlight through the skin-vitamin D endocrine system are considered as alternate or additional to the neuroendocrine effects of the visual component of light through the retino-diencephalic input. The extensive distribution of soltriol nuclear receptor cells, revealed by autoradiography with tritium-labeled 1,25 dihydroxycholecalciferol (vitamin D, soltriol) and related effects, indicate an involvement of vitamin D-soltriol in the actinic induction of seasonal biorhythms. This is considered to be independent of the traditionally assigned effects of vitamin D on systemic calcium regulation. Skin-soltriol mediated seasonal, and to a degree daily, genomic activation involves many target regions in the brain. These include neurons in the central nucleus of the amygdala, in the linked part of the bed nucleus of the stria terminalis, in periventricular hypothalamic neurons, dorsal raphe nucleus, reticular thalamic nucleus and autonomic, endocrine as well as sensory and motor components of the brainstem and spinal cord. Additional to the eye-regulated “suprachiasmatic clock”, existence of a soltriol-vitamin D regulated neural “timing circuit(s)” is proposed. Both, activational and organizational effects of soltriol on mature and developing brain regions, respectively are likely to play a role in the regulation of neuronal functions that include the modulation and entrainment of biorhythms. Soltriol's central effects correlate with peripheral effects on elements in skin, bone, teeth, kidney, intestine, heart and blood vessels, endocrine organs, and tissues of the immune and reproductive system.

Genetic Study of Eye Cancer in Cattle

Heritabilities, phenotypic, and genetic correlations of lid and corneoscleral pigment and eye lesions associated with "cancer eye" were investigated in 2,831 Herefords from 34 herds in 21 states and one Canadian province. The results indicated that lid and corneoscleral pigment were heritable and genetically correlated. Corneoscleral pigment had a direct protective effect on lesions developing at the corneoscleral junction. Corneoscleral pigment and lesion development were apparently not genetically related, and lesion development was not heritable. These findings lead to the general conclusion that the genetic effect on pigment determines to a large extent the degree to which the eye is susceptible to some carcinogenic agent. The ultraviolet light component of sunlight is the most plausible carcinogenic agent that affects the eye. A genetic-environmental interaction is indicated, whereby an increasing amount of pigment lessens both susceptibility and the probability of lesion development, but whether lesions develop in the absence of pigment depends to a large extent on the amount of ultraviolet light to which the eye is exposed. The findings further indicate that the disease is controllable by selective breeding for increased amounts of lid pigment, which should lead to a correlated increase in lid and corneoscleral pigment and a decrease in lesions.

Influence of the spectral composition of the pump radiation on the lasing and the spectral-luminescence characteristics of a YAlO3:Nd3+crystal

An investigation was made of the influence of the spectral composition of the exciting light on the lasing and spectral-luminescence characteristics of a YAlO3:Nd3+ crystal. The spectral and relaxation characteristics of the photoinduced absorption, associated with the formation of color centers in the crystal, were determined. The induced absorption could increase the evolution of heat in the active element, but it did not influence the efficiency of filling the upper active level 4F3/2 of the Nd3+ ion. The mechanism responsible for the reduction in the lasing efficiency of the YAlO3:Nd3+ crystal in the presence of an ultraviolet component in the pump radiation spectrum was identified.

Peculiar ultraviolet absorbing moieties of human osteoarthritic cartilage

The ultraviolet absorbing components of human cartilage have been measured by microspectrophotometry. The characteristics of the chondrocytes appeared to be identical, irrespective of the pathology. However the matrix of osteoarthritis cartilage contained components that absorbed maximally in the region of 270 to 250 nm; such components were not found in the matrix of cartilage of non-arthritic joints. Substances that absorb maximally in this region of the ultraviolet could generate free radicals.

Solar Intensity and Sun Protection

In Reply.— Drs Weyrauch and Boiko cite the examples of Charleston, SC (33 latitude and 862 BTU per day solar radiation in July) and Spokane, WA (48 and 1314 BTU) to illustrate that factors other than latitude affect the overall intensity of solar radiation. Other complexities are worth noting. Cloud cover affects the average intensity of solar radiation, but the peak intensity on sunny days may be particularly relevant for melanoma. Furthermore, it is likely that the short wavelength ultraviolet component of sunlight is primarily responsible for the ability of the sun to cause melanoma, and this component is more dependent than other wavelengths on latitude.1