The effect of ultraviolet radiation on human viral infections

Exposure to UV radiation is recognized to suppress cell-mediated immunity and therefore could adversely affect the course of a viral infection. Rodent models of viral infection confirm this possibility but the situation in human subjects is not so clear, apart from two exceptions. These are herpes simplex, in which sunlight exposure can cause reactivation, and certain papillomavirus types in which sunlight exposure can lead to the development of nonmelanoma skin cancer. In both cases, there are UV response elements in the viral genomes that alter the normal interactions between the viruses and the host following exposure, and UV-induced effects on the immune response occur in addition. These complex mechanisms are discussed, and the situation regarding UV radiation and viral exanthems plus other viruses, including the retroviruses, summarized. Finally viral vaccination is considered in the context of UV exposure and the importance of the host's genetic background emphasized. Further research is required to evaluate whether sunlight can significantly affect the resistance to common viral infections and vaccines.     

Effects of solar radiation on the human immune system.

On UV irradiation of the skin, a complex cascade of immunological changes results, initiated by cutaneous chromophores and ending in suppression of some local and systemic immune responses. In this review, the stages in this process are outlined first, concentrating on the roles of DNA and urocanic acid as photoreceptors. Evidence indicating UV-induced immunomodulation of delayed hypersensitivity and resistance to infectious diseases in human subjects follows. Aspects of genetic susceptibility to the immunosuppressive effects of UV exposure and extrapolation of the data obtained in animal models to the human situation are included. Finally uncertain and unknown factors relating to the impact of UV on the human immune system are discussed.     

The effect of ultraviolet radiation upon osmoregulation in Paramecium

Abstract Paramecium multimicronucleatum was irradiated with U.V. in solutions of differing osmotic pressures and ionic content. The rates of contraction and the diameters of the anterior contractile vacuoles were measured and changes in the volumes of solution entering the contractile vacuoles upon U.V. irradiation for paramecia maintained in solutions of differing ionic content were calculated. The volume of fluid entering the contractile vacuoles of paramecia irradiated (1) in standard balanced salt solution (SBSS) was regulated by a compensatory mechanism at lower U.V. doses but increased after relatively large U.V. doses; (2) in distilled water, increased after much smaller U.V. doses; (3) in isotonic balanced salt solution, showed little change upon irradiation. Increased osmotic pressure (with added sucrose) was found to reduce u.v.-induced blistering of the pellicle, but in general U.V. damage was similar to that of paramecia in solutions of identical ionic content but lacking sucrose. Paramecia in SBSS with added sucrose to make it isomotic to the interior of the cell ruptured only after doses larger than for paramecia in SBSS lacking sucrose. Cell rupture of paramecia in solutions containing high CaCl₂ concentrations generally occurred later than for those in SBSS. High KCI concentration (unbalanced salt solution) in the presence of high CaCl₂ concentration provided some protection from U.V. irradiation to the paramecia. High NaCl concentration (unbalanced salt solution) in the presence of high CaCl₂ concentration appeared to increase u.v. damage to paramecia. Paramecia were most resistant to u.v. irradiation, as judged by the above criteria, when present in balanced salt solution enriched with calcium, thus simulating pond water.     

Effect of ultraviolet radiation on a metal/polyamidine system

An increase in the optical transmission in electronic spectra for metal/poly(1,10-decamethylene-acetamidine) systems after UV irradiation is observed, in contrast to polymer and metal films investigated separately where there was no such effect. The increase is explained by changes in the distribution of the electric charge induced by UV irradiation at the metal/polymer interface in a polymer film.     

The effect of the eye's surface topography on the total irradiance of ultraviolet radiation on the inner canthus

Basal cell carcinoma is the most commonly occurring skin cancer in sub tropical climates. The link between ultraviolet radiation (UVR) and basal cell carcinomas (BCC) is strong. Numerous studies have investigated the spatial distribution of BCCs over the head and neck region and the relative UVR dose, with little or no correlation found between the UVR dose and occurrence rates. This is particularly noted in the inner canthus region. The inner canthus' field of view is restricted by the eye brow ridge, eye orbit and the cheek bone. Yet, the occurrence rate here of BCC's when compared to other regions that are more directly exposed to the environment is significantly higher. A possible causal effect for the increase in occurrence rate in this region is the focussed reflection of UVR from the tear film surface associated with the eye not previously considered in earlier studies. This paper investigates the potential for the surface topography of the eye to reflect focussed radiation towards the inner canthus using a ray tracing programme where the analysis is conducted at a cellular level. Defined hot spots, or striations, of increased irradiation were evidenced across the surface of the inner canthus. This increase in irradiation was not observed with macroscopic detectors which also possibly explain why this increased dose has not previously been detected during environmental measurements with large detectors on manikins or humans.     

Acid-generating effect of plasma species and pulsed ultraviolet plasma radiation

The yield of acid residues generated in water at pH 3–13 by pulsed plasma radiation of spark discharge with a power of 0.59 W has been studied. The power per pulse of electrical discharge has been optimized to obtain the maximum chemical effect in water. The results are compared with similar data obtained by treatment with 900-W gliding discharge. It has been found that the energy efficiency of pulsed plasma radiation is 100 times that of gliding discharge plasma. The results make it possible to clarify the mechanism of the gliding discharge-induced formation of peroxynitrite.     

The effect of the short wavelength ultraviolet radiation. An extension of biological dosimetry to the UV-C range

Polycrystalline uracil thin layer can be used as biological dosimeter for assessing exposure to UV radiation. The dimerization and reversion efficiency of the ultraviolet radiation in the UV-B and the UV-C range were quantified on polycrystalline uracil thin layers irradiated with quasi-monochromatic radiation using interference filters of 10nm bandwidth. The dimer formation and monomerization (reversion) dose-effect relations were determined by optical spectroscopy. The decrease of the OD value of the uracil thin layer at 288 nm was taken as a measure of the dimer formation, while the increase of the OD of a completely irradiated (until reaching the saturation level) uracil layer was taken as the sign of the monomerization. The two processes in the UV-B and the UV-C range take place simultaneously, the individual characterization of the dimerization efficiency was performed from the initial slope of the dimerization dose-effect function and an action spectrum for dimerization was constructed in the UV-C range too. The reversion efficiency was found to be practically the same with all of the investigated wavelengths: 200 nm, 210 nm, 220 nm, 230 nm, 240 nm The possible biological relevance of the reversion of dimers are discussed.     

Effects of ultraviolet radiation on aqueous polyelectrolyte solutions

The effects of ultraviolet radiation on dilute aqueous solutions of poly(acrylic acid) and of other polyelectrolytes were studied by viscosity measurements in connection with the effects of ionizing radiation. It was found that ultraviolet light of wavelength below about 2300 Å brought about degradation of polymer chains mainly by indirect action via water, while light of wavelength above 2300 Å caused degradation by direct action in some polymers. It was deduced from the experiments that the protective effect of NaCl could be largely attributed to a decrease in the indirect action. It was also found that a low concentration of methanol was effective in preventing degradation by direct action, although methanol promoted degradation when present in high concentration. Since the promotive effect was not observed when light of wavelength below 3700 Å was eliminated by a filter, this effect was attributed to active products of the irradiation of methanol.     

Lower body anatomical distribution of solar ultraviolet radiation on the human form in standing and sitting postures

Humans undertake their daily activities in a number of different postures. This paper aims to compare the anatomical distribution of the solar erythemal UV to human legs for standing and sitting postures. The exposure ratios to the legs (ratio of the UV exposure to a particular anatomical site compared to the ambient) have been measured with UV dosimeters for standing and sitting postures of a manikin. The exposure ratios for the legs ranged from 0 to 0.75 for the different anatomical sites for the sitting posture in summer (December through February) compared to 0.14 to 0.39 for the standing posture. In winter (June through August) the exposure ratios ranged from 0.01 to 0.91 for sitting to 0.17 to 0.81 for standing. For the anterior thigh and shin, the erythemal UV exposures increased by a factor of approximately 3 for sitting compared to standing postures. The exposure ratios to specific anatomical sites have been multiplied by the ambient erythemal UV exposures for each day to calculate the annual exposures. The annual erythemal exposures to the anterior thigh and ankle were predicted to be higher than 800 MED for humans sitting outdoors each day between noon and 13:00 h Australian Eastern Standard Time (EST). For humans standing outdoors during this time, the annual erythemal UV exposure averaged over each leg site was 436 MED, whereas, the averaged annual erythemal UV exposure was 512 MED for the sitting posture. Similarly, the annual erythemal UV exposure averaged over each of the sites was 173 MED for humans standing outdoors between 09:00 h EST and noon each Saturday morning and 205 MED for humans sitting outdoors during this time. These results show that there is increased risk of non-melanoma skin cancer and malignant melanoma to the lower body if no UV preventative strategies are employed while in a sitting posture compared to a standing posture.     

Impact of ultraviolet radiation on the performance of polymer electrolyte membrane

Journal of Solid State Electrochemistry - The effect of ultraviolet (UV) radiation, with wide range of wavelengths, on Nafion 112 membrane was studied at different UV exposure times up to...     

The effect of a vitamin A acetate diet on ultraviolet radiation-induced immune suppression as measured by contact hypersensitivity in mice

The adverse health effects caused by increased exposure to ultraviolet radiation (UVR) due to deterioration of stratospheric ozone are of major concern. These health effects include sunburn, skin cancer, cataracts and immune suppression. Immune suppression has been associated with the release of cytokines, a defect in antigen presentation, induction of suppressor T cells and suppression of contact hypersensitivity (CH). CH is typically assessed by the mouse ear swelling test (MEST). Previous studies have demonstrated enhanced CH responses with vitamin A acetate (VAA) dietary supplementation assessed by MEST and the local lymph node assay (LLNA). To determine the effect that VAA has on UVR-induced immune suppression, we examined both the induction and elicitation phases of CH using murine models. The MEST was used to evaluate the interaction of UVR and VAA on CH elicitation. However, a positive MEST response requires that the induction phase as well as the elicitation phase of CH be functional. The LLNA was used to evaluate the interaction of UVR and VAA only on CH induction. We tested the hypothesis that mice maintained on a VAA-enriched diet are more resistant to UVR-induced immune suppression (CH) than those maintained on a control diet. Mice were maintained on a VAA-enriched or the control diet for 3 weeks and then exposed to UVR 3 days prior to sensitization with 2,4-dinitrofluorobenzene (DNFB). VAA enhanced the MEST response in both UVR-exposed and non-UVR-exposed mice. The VAA-enriched diet did not significantly alter the LLNA response in either UVR- or non-UVR-exposed mice. However, there was significant suppression in CH by UVR as measured by the LLNA. These results indicate that (1) the VAA-enriched diet does not restore the number of proliferating cells in the CH induction phase of UVR-induced immunosuppression; (2) the immunosuppressive effects of UVR affect the induction phase of CH; and (3) the LLNA should be examined as an alternative to the MEST for measurement of UVR-induced immunosuppression. The data indicate that the VAA-enriched diet enhanced the elicitation response (MEST) but not the earlier induction phase (LLNA). Further studies are necessary to define mechanisms of action, but modulation of cytokines and effects of specific lymphocyte subsets, as well as systemic effects and local modulation at the site of elicitation are possible. Additionally, future studies to evaluate the effect of the VAA-enriched diet when multiple doses of both UVR and DNFB are used would be of interest for both the LLNA and MEST end-points.     

The microwave radiation effect on the polymerization of styrene

Styrene was cured by microwave radiation at two different powers: 300 and 500 W. The temperature profile of the sample during the microwave curing process was determined to select a suitable temperature for comparison with the conventional method of cure. The results indicate a similar comparable temperature of about 80°C irrespective of the microwave power used. The percentage conversion of the cure was followed by Fourier transform infrared (FTIR) spectroscopy. The thermal polymerization at 79(±1)°C displayed a gradual increase in the rate of reaction at the gel effect from about 30 to 50% conversion of the reaction. The microwave cure at 300 and 500 W displayed a large and sharp gel effect from about 20 to 69 and 64% conversion of the reaction, respectively. The limiting conversion decreased with increase in microwave power which was also observed in the polymerization of methyl methacrylate (MMA). Based on similarity in temperature and reaction conditions, the 500 W cure was found to show a reaction rate enhancement of 190% and the 300 W cure 120%. A comparison of microwave induced reactions with thermal methods, therefore, must also specify the microwave power used. © 1996 John Wiley & Sons, Inc.     

The effect of geometry on the fluorescence radiation field

In X-ray fluorescence spectroscopy, a photon beam is focused on the sample to induce the production of characteristic radiation carrying useful information on the composition of the target. Even if the interpretation of the measurement is simple, the quantification of the total emitted intensity is not straightforward because the primary photons are produced deep in the target and the radiation reaching the detector can be sensibly modified by the interactions which the photons undergo before leaving the specimen. In this work we show that the geometry of the system plays an important role in determining the properties of the radiation field.     

Sublethal effects of ultraviolet A radiation on Enterobacter cloacae

We report the sublethal effects of ultraviolet A (UVA) on Enterobacter cloacae in comparison with those produced in Escherichia coli. UVA-induced sublethal effects were investigated in either bacterial membrane and at tRNA level. Limited dependence on oxygen concentration for photoinduced inhibition of biochemical membrane functions and low levels of oxidative damage during the irradiation period were found in En. cloacae. On the other hand, ultraviolet spectroscopy and reversed-phase HPLC analysis of hydrolysed tRNA showed that radio induced damage to tRNA is similar in En. cloacae and E. coli. Nevertheless, growth delay induced by UVA in En. cloacae was shorter than that found in E. coli submitted to the same experimental conditions. A limited post-irradiation ppGpp accumulation and the absence of any influence of the membrane damage on the growth delay extent seem to be responsible for the shortness of this effect in En. cloacae. Most of the differences between En. cloacae and E. coli could be attributed to an increased ability of En. cloacae to overcome oxidative stress during UVA exposure.     

The effect of environment on cystine disruption by ultraviolet light

When cystine is irradiated at pH 1 by 254-nm u.v. the following yields are observed: 4 cystines → 5.2 cysteines + 2.8NH₃. Thus, SH production accounts for only 0.65 of the cystine destruction; further C-S breakage to give alanine or serine is not efficient. The yields for cystine and glutathione destruction are essentially the same at pH 1. However the presence of the glutamic and glycine residues stabilize the cystine in glutathione so that NH₃ is not lost until the peptide bonds are hydrolyzed. Increasing the pH from 1 to 8.6 increases the yield of cystine destruction in glutathione by 50 per cent. The yield of cystine destruction is greater in both compounds when O₂ is present during irradiation (e. g. the cysteic acid yield in glutathione is increased by 50 times). The overall production of SH varies by a factor of 2 in the four proteins-insulin, RNase, trypsin and lysozyme. The present data further support the earlier observation that radiation damage is quite non-random in RNase: at least two and perhaps three of the four constituent cystines must be disrupted before activity is lost: i.e. the most radiosensitive cystines are not critical for enzymic activity. Similarly, in both trypsin and lysozyme the integrity of the most radiosensitive cystines also does not appear to be critical for the retention of enzymic potential. In insulin, however, all three cystines appear to be crucial for activity and to have approximately equal radiosensitivities. These differences in sensitivity of cystines in different proteins must depend specifically upon energy transfer and/or chemical interactions between the chromophoric groups. If yields are calculated on the basis of those quanta absorbed only in the cystines, values about 5 to 8 times greater than those in the model compounds cystine and oxixized glutathione are obtained. The yields of cystine destruction are much higher in those protiens which contain trypotophan.     

Effects of short- and long-term ultraviolet B irradiation on the immune system of the common carp (Cyprinus carpio)

Carp (Cyprinus carpio) were repeatedly exposed to 0, 60, 120 and 240 mJ/cm2 ultraviolet B (UVB) radiation three times in 1 week (short-term exposure) or 12 times in 4 weeks (long-term exposure). The effect of UVB on the functioning of the carp immune system was studied on day 2 after the final irradiation. After short-term UVB exposure, the whole-blood respiratory burst and cytotoxic activity were markedly enhanced, with parallel responses in both the number of circulating granulocytes and in the plasma cortisol concentration of the fish. These changes were not detectable after long-term exposure. The respiratory burst by head kidney granulocytes was suppressed dose dependently after both exposures, but cytotoxic activity was not affected. Exposure to UVB also modulated lymphocyte functions: nonstimulated and PHA-stimulated proliferation of head kidney lymphocytes in vitro was enhanced by both short-term and long-term exposure. LPS-stimulated proliferation was not affected by exposure nor was the number of immunoglobulin-secreting cells in the head kidney. In long-term exposure, the highest dose reduced the level of plasma IgM. This study indicates that UVB irradiation induces immunomodulation in the blood and head kidney of the carp and that the effects of short- and long-term exposure differ from each other. The results emphasize the potentially harmful impact of increased solar UVB radiation on fish immune functions.     

Neutrophil infiltration in normal human skin after exposure to different ultraviolet radiation sources

Exposure of the skin to UV radiation can lead to a local infiltration of neutrophils. Not much is known on whether the infiltration of neutrophils in the irradiated skin is UV source dependent. In this study we compared different UV sources (solar-simulated radiation [SSR], narrowband [NB]-UVB, broadband [BB]-UVB and UVA1) in their potency to induce neutrophil infiltration in normal human skin after exposure to two times the minimal erythema dose of UV radiation. Biopsies were collected from irradiated buttock skin 6 and 24 h after irradiation and from nonirradiated skin. The presence, distribution and amount of skin-infiltrated neutrophils were determined using immunohistochemical staining. Analysis revealed that SSR was most effective in inducing neutrophil infiltration. NB-UVB gave a neutrophil influx pattern similar to that seen with SSR but in smaller numbers. BB-UVB and UVA1 were far less potent in inducing neutrophil infiltration compared with SSR or NB-UVB. Our findings indicate that neutrophil infiltration in the UV-irradiated skin is UV source dependent. When the spectra emitted by the different UV sources were compared UVB seemed to be more effective than UVA in inducing neutrophil infiltration. Furthermore, our results suggest that longer wavelengths within the UVB range are mostly responsible for the infiltration of neutrophils in the UV-irradiated skin.     

Simulating the experimental vacuum ultraviolet radiation of rare-gases plasma

Experimental excimer continua emitted by electric discharge plasma of krypton and xenon were interpreted as the ¹ Σ _u ⁺ → ¹ Σ _g ⁺ bound-free transitions. The relative populations of the lower vibrational levels of the ¹ Σ _u ⁺ state were derived fitting experimental spectra with the theoretical ones.     

Depletion of cutaneous glutathione by ultraviolet radiation

Supplemental antioxidants may have a role in ameliorating or preventing the actinic damage that can lead to cutaneous disorders such as skin cancer, hyperpigmentation, and premature aging. Glutathione is an important endogenous antioxidant and fulfills various protective functions in the skin. Irradiation of hairless mice with short (UVB) or long (UVA) wavelength ultraviolet radiation or with UVA combined with a photosensitizing psoralen (PUVA) can deplete skin glutathione levels. Ultraviolet B irradiation causes rapid transient fluctuations in the epidermal glutathione level and the relative amount present as the oxidized form. Ultraviolet A irradiation can deplete epidermal and dermal glutathione for several hours but requires much higher doses than UVB. PUVA treatments may lead to extensive and prolonged depletions of epidermal and dermal glutathione, the severity of which is dependent on the psoralen dose and may last for several days. These transient depletions, oxidations, and sometimes rapid recoveries of cutaneous glutathione levels are compatible with a role for glutathione as an endogenous photoprotective agent in the skin. Experimental evidence supports such a role: for example severe skin edema develops in mice only after about 50% of the glutathione has been depleted by PUVA treatment. Although different mechanisms are involved in each case, glutathione depletion may contribute to the production of phototoxicity by UVB, UVA, and by PUVA. Understanding the depletion mechanisms may allow the development of strategies aimed at preventing loss of cutaneous glutathione, and at reinforcing the natural protective functions of this critical cell component.