UV-B Lamps Research Articles

A new filter that accurately mimics the solar UV‐B spectrum using standard UV lamps: the photochemical properties, stabilization and use of the urate anion liquid filter

The physiological effects unique to solar ultraviolet (UV)-B exposure (280-315 nm) are difficult to accurately replicate in the laboratory. This study evaluates the effectiveness of the sodium urate anion in a liquid filter that yields a spectrum nearly indistinguishable from the solar UV-B spectrum while filtering the emissions of widely used UV-B lamps. The photochemical properties and stability of this filter are examined and weighed against a typical spectrum of ground-level solar UV-B radiation. To test the effectiveness of this filter, light-saturated photosynthetic oxygen evolution rates were measured following exposure to UV-B filtered either by this urate filter or the widely used cellulose acetate (CA) filter. The ubiquitous marine Chlorophyte alga Dunaliella tertiolecta was tested under identical UV-B flux densities coupled with ecologically realistic fluxes of UV-A and visible radiation for 6 and 12 h exposures. These results indicate that the urate-filtered UV-B radiation yields minor photosynthetic inhibition when compared with exposures lacking in UV-B. This is in agreement with published experiments using solar radiation. In sharp contrast, radiation filtered by CA filters produced large inhibition of photosynthesis.

How Realistically Does Outdoor UV-B Supplementation with Lamps Reflect Ozone Depletion: An Assessment of Enhancement Errors

Limitations in the realism of currently available lamps mean that enhancement errors in outdoor experiments simulating UV-B radiation effects of stratospheric ozone depletion can be large. Here, we assess the magnitude of such errors at two Finnish locations, during May and June, under three cloud conditions. First we simulated solar radiation spectra for normal, compared with 10% and 20% ozone depletion, and convoluted the daily integrated solar spectra with eight biological spectral weighting functions (BSWFs) of relevance to effects of UV on plants. We also convoluted a measured spectrum from cellulose-acetate filtered UV-B lamps with the same eight BSWFs. From these intermediate results we calculated the enhancement errors. Differences between locations and months were small, cloudiness had only a minor effect. This assessment was based on the assumption that no extra enhancement compensating for shading of UV radiation by lamp frames is performed. Under this assumption errors between spectra are due to differences in the UV-B effectiveness rather than differences in the UV-A effectiveness. Hence, conclusions about plant growth from past UV-supplementation experiments should be valid. However, interpretation of the response of individual physiological processes is less secure, so results from some field experiments with lamps might need reassessment.

Expression of tissue inhibitors of matrix metalloproteinases 1 and 2 in corneal epithelium after UV irradiation

Abstract Purpose Tissue inhibitors of metalloproteinases (TIMPs) are capable of inhibiting the activities of all known matrix metalloproteinases (MMPs) and therefore they play a key role in maintaining the balance between synthesis and degradation of basic extracellular matrix components (collagens, glycosaminoglycans) in the normal cornea. However, under pathological conditions, disruption of this balance may appear due to the increased expression of MMPs or decreased expression of TIMPs. Purpose of this study was to investigate whether changes in expression of TIMPs might contribute to increased proteolytic activity of MMPs in corneas irradiated by UV rays. Methods In the first group of rabbits the corneas were irradiated with UVA lamp (365 nm, once a day during 4 days, a dose per day 1.01 J/cm2), in the second group with UVB lamp (312 nm, once a day during 4 days, a dose per day 1.01 J/cm2). Normal corneas served as controls. TIMP‐1 and TIMP‐2 were examined in cryostat sections immunohistochemically using mouse monoclonal anti‐TIMP‐1 and anti‐TIMP‐2 antibodies. Results Immunohistochemical examination showed that UVA rays did not change the expression of TIMPs studied in the corneal epithelium. In contrast, UVB rays induced the decreased expression of TIMPs in corneal epithelial cells. From both enzymes investigated in UVB irradiated corneas the decrease of TIMP‐1 expression was more significant than expression of TIMP‐2. Conclusion Even if further studies are necessary, our results point to the suggestions that insufficient inhibition of MMPs due to the decreased presence of TIMPs in corneas irradiated by UVB rays may lead to corneal damage from excessive proteolytic degradation of corneal proteins.

Laboratory Studies on Pipeline Coating Materials under Accelerated Weathering Condition

Laboratory test has been carried out to assess the rate of degradation of dielectric strength of different pipeline coating materials viz coal tar enamel, hot applied coal tar tape, cold applied polyolefin tape, coal tar epoxy, high build epoxy, polyurethane & 3LPE coating after accelerated weathering in QUV using 313 UVB lamp maintaining a cycle of 4 hour UV and 4 hrs. condensation and after 500 hours salt spray as per ASTM B117. This test is important since the corrosion control systems of most pipelines consist of the combination of coating and cathodic protections. It is desirable that the dielectric properties of the coating deteriorate at the minimum rate possible. Deteriorations of coating with time would lead to a constant requirement of additional cathodic protection current which would be both a technical & economic burden on the pipeline operator. This paper highlights to establish the suitability of proper coating material with respect to cathodic protection.

Photodermatitis and Photokeratoconjunctivitis in a Ball Python (Python regius) and a Blue-Tongue Skink (Tiliqua spp.)

A male ball python (Python regius) and a female blue tongue skink (Tiliqua spp.) of unknown age were evaluated for anorexia, lethargy, excessive shedding, corneal opacity (python), and weight loss (skink) of approximately three weeks' duration. These animals represented the worst affected animals from a private herpetarium where many animals exhibited similar signs. At necropsy, the python had bilateral corneal opacity and scattered moderate dysecdysis. The skink had mild dysecdysis, poor body condition, moderate intestinal nematodiasis, and mild liver atrophy. Microscopic evaluation revealed epidermal erosion and ulceration, with severe epidermal basal cell degeneration and necrosis, and superficial dermatitis (python and skink). Severe bilateral ulcerative keratoconjunctivitis with bacterial colonization was noted in the ball python. Microscopic findings within the skin and eyes were suggestive of ultraviolet (UV) radiation damage or of photodermatitis and photokeratoconjunctivitis. Removal of the recently installed new lamps from the terrariums of the surviving reptiles resulted in resolution of clinical signs. Evaluation of a sample lamp of the type associated with these cases revealed an extremely high UV output, including very-short-wavelength UVB, neither found in natural sunlight nor emitted by several other UVB lamps unassociated with photokeratoconjunctivitis. Exposure to high-intensity and/or inappropriate wavelengths of UV radiation may be associated with significant morbidity, and even mortality, in reptiles. Veterinarians who are presented with reptiles with ocular and/or cutaneous disease of unapparent cause should fully evaluate the specifics of the vivarium light sources. Further research is needed to determine the characteristics of appropriate and of toxic UV light for reptiles kept in captivity.

Changes in expression of matrix metalloproteinases 1 and 8 in corneal epithelial cells after UV irradiation

Abstract Purpose Matrix metalloproteinases 1 and 8 (MMP‐1 and MMP‐8) are collagenolytic enzymes that are associated with many ocular inflammatory diseases, such as uveitis, ulcerative keratitis, and ocular rosacea. It is suggested, that MMP‐1 and MMP‐8 are mainly produced by inflammatory cells so that an increased incidence of these enzymes in the cornea is associated with neutrophil infiltration. Based on our previous findings dealing with the coincidence of the expression of proteolytic enzymes (MMP‐2 and MMP‐9) with the severity of corneal injury induced by UV irradiation, the aim of this study was to investigate the effect of UVA and UVB rays on expression of MMP‐1 and MMP‐8 in the corneal epithelium. Methods In the first group of rabbits the corneas were irradiated with UVA lamp (365 nm, once a day during 4 days, a dose per day 1.01 J/cm2), in the second group with UVB lamp (312 nm, once a day during 4 days, a dose per day 1.01 J/cm2). Normal corneas served as controls. MMP‐1 and MMP‐8 were examined in cryostat sections immunohistochemically using sheep polyclonal anti‐MMP‐1 and mouse monoclonal anti‐MMP‐8 antibodies. Results Results show that UVA rays do not change expression of MMPs studied in corneal epithelium. In contrast, UVB rays induce overexpression of both MMPs in corneal epithelial cells. Conclusion Comparing the effect of the same doses of UVA and UVB rays with the normal cornea, where the enzymes are only slightly (MMP‐1) or moderately (MMP‐8) pronounced in the epithelium, UVB rays (not UVA rays) evoked highly increased expression of both MMPs in irradiated corneal epithelial cells. The possible influence of overexpression of MMPs due to UVB‐exposure on the development of corneal inflammation will be the aim of our next study.

The Role of Nitric-oxide Synthase in the Regulation of UVB Light-induced Phosphorylation of the α Subunit of Eukaryotic Initiation Factor 2

UV light induces phosphorylation of the alpha subunit of the eukaryotic initiation factor 2 (eIF2alpha) and inhibits global protein synthesis. Both eIF2 kinases, protein kinase-like endoplasmic reticulum kinase (PERK) and general control of nonderepressible protein kinase 2 (GCN2), have been shown to phosphorylate eIF2alpha in response to UV irradiation. However, the roles of PERK and GCN2 in UV-induced eIF2alpha phosphorylation are controversial. The one or more upstream signaling pathways that lead to the activation of PERK or GCN2 remain unknown. In this report we provide data showing that both PERK and GCN2 contribute to UV-induced eIF2alpha phosphorylation in human keratinocyte (HaCaT) and mouse embryonic fibroblast cells. Reduction of expression of PERK or GCN2 by small interfering RNA decreases phosphorylation of eIF2alpha after UV irradiation. These data also show that nitric-oxide synthase (NOS)-mediated oxidative stress plays a role in regulation of eIF2alpha phosphorylation upon UV irradiation. Treating the cells with the broad NOS inhibitor N(G)-methyl-l-arginine, the free radical scavenger N-acetyl-l-cysteine, or the NOS substrate l-arginine partially inhibits UV-induced eIF2alpha phosphorylation. The results presented above led us to propose that NOS mediates UV-induced eIF2alpha phosphorylation by activation of both PERK and GCN2 via oxidative stress and l-arginine starvation signaling pathways.

Luminescent properties of Pr3+-sensitized LaPO4:Gd3+ ultraviolet-B phosphor under vacuum-ultraviolet light excitation

Luminescent properties of Pr3+-sensitized LaPO4:Gd3+ under vacuum-ultraviolet (vuv) light excitation have been investigated. The energy transfer probably occurs from the 5d levels in Pr3+ ions to Gd3+ ions under 172nm light excitation. LaPO4:Gd3+,Pr3+ shows efficient ultraviolet-B (uv-B) emission at 312nm, whose peak intensity reaches its maximum at Gd=35mol% and Pr=5mol%. (La0.65Gd0.35)0.95Pr0.05PO4 is about 1.6 times higher than a typical uv-B phosphor for vuv lamp, Y0.75Gd0.25Al3(BO3)4, in Gd3+-emission intensity under 172nm light excitation. This result implies that the Pr3+-sensitized LaPO4:Gd3+ is a candidate of uv-B phosphors for xenon-excimer discharge vuv lamps. In order to evaluate the effect of the narrow-band uv-B emission by LaPO4:Gd3+,Pr3+ phosphor, irradiation test on DNA was performed. The irradiation damage of pUC 18 DNA by the narrow-band uv-B light from the LaPO4:Gd3+,Pr3+ phosphor is in the same magnitude as that by uv-A light from a filtered Hg lamp, even though the uv-B lamp is higher than the uv-A lamp in power density and photon energy.

The Essential Role of p53 in Hyperpigmentation of the Skin via Regulation of Paracrine Melanogenic Cytokine Receptor Signaling

Hyperpigmentation of the skin is characterized by increases in melanin synthesis and deposition. Although considered a significant psychosocial distress, little is known about the detailed mechanisms of hyperpigmentation. Recently, the tumor suppressor protein p53 has been demonstrated to promote ultraviolet B-induced skin pigmentation by stimulating the transcription of a melanogenic cytokine, POMC (pro-opiomelanocortin), in keratinocytes. Given that p53 can be activated by various kinds of diverse stresses, including sun exposure, inflammation, and aging, this finding led us to examine the involvement of p53 in cytokine receptor signaling, which might result in skin hyperpigmentation. Immunohistochemical and reverse transcription-PCR analyses revealed the increased expression and phosphorylation of p53 in the epidermis of hyperpigmented spots, accompanied by the higher expression of melanogenic cytokines, including stem cell factor, endothelin-1, and POMC. The involvement of p53 in hyperpigmentation was also indicated by the significantly higher expression of p53 transcriptional targets in the epidermis of hyperpigmented spots. Treatment of human keratinocytes and melanocytes with known p53 activators or inhibitors, including pifithrin-alpha (PFT), demonstrated significant increases or decreases, respectively, in the expression of melanogenic factors, including cytokines and their receptors. Additionally, PFT administration abolished stem cell factor-induced phosphorylation of mitogen-activated protein kinase in human melanocytes. Furthermore, when organ-cultured hyperpigmented spots, in vitro human skin substitutes, and mouse skin were treated with PFT or p53 small interfering RNA, the expression of melanogenic cytokines and their receptors was significantly decreased, as were levels of tyrosinase and melanogenesis. Taken together, these data reveal the essential role of p53 in hyperpigmentation of the skin via the regulation of paracrine-cytokine signaling, both in keratinocytes and in melanocytes.

Secondary VOC emissions from flooring material surfaces exposed to ozone or UV irradiation

Chemical reactions on the surface of building materials can lead to secondary emissions from these materials that influence indoor air quality. Many studies have been made on the physical processes that influence material emissions. However, there are only a few studies on secondary emissions resulting from exposure of building material surfaces to ozone or ultraviolet (UV) irradiation. Therefore, this study was aimed at elaborating on the emission of chemicals resulting from chemical reactions initiated by the exposure of the surface of flooring materials to ozone or UV irradiation. The laboratory tests were conducted to estimate gas-phase emissions from the flooring materials when they were exposed to ozone or various kinds of light irradiation (infrared, sunlight, UV-A and UV-B lamps). The infrared and sunlight lamps significantly increased the temperature of the test specimens and, in turn, increased the emission rate for various organic compounds. The flooring materials used in this study had been treated with UV-cured surface coatings during their manufacturing. As a result, when exposed to UV irradiation, chemical transformations occurred resulting in the emission of a number of secondary products, including formaldehyde, acetaldehyde, cyclohexanone and benzaldehyde. Ozone reacted with chemicals present in the flooring materials to increase the emission rates of formaldehyde and acetaldehyde. Hence, the exposure of ozone and UV irradiation increased the secondary emissions of formaldehyde, even though the low formaldehyde emission type of flooring material was employed.

The effect of UVA and UVB irradiation of the rabbit cornea on matrix metalloproteinase 2 and 9 expression in the corneal epithelium

Abstract Purpose Matrix metalloproteinases (MMPs) synthetisized by corneal cells are primarily responsible for degrading and remodeling corneal stromal extracellular matrix. They participate in various pathophysiological processes in the cornea, including corneal wound healing and ocular diseases. Purpose of this study was to investigate the effect of UVA and UVB rays on the expression of matrix metalloproteinases (MMP‐2 and MMP‐9) in the corneal epithelium. Methods In the first group of rabbits the corneas were irradiated with UVA lamp (365 nm, once a day during 4 days, a dose per day 1.01 J/cm2 ). In the second group of rabbits the corneas were irradiated with UVB lamp (312 nm, once a day during 4 days, a dose per day 1.01 J/cm2). Matrix metalloproteinases MMP‐2 and MMP‐9 were examined on cryostat sections immunohistochemically using mouse monoclonal anti‐MMP‐2 and anti‐MMP‐9 antibodies. Results Immunohistochemical examination showed that UVA rays did not change the expression of MMPs studied in the corneal epithelium. In contrast, UVB rays induced the increased expression of MMPs in corneal epithelial cells. From both enzymes investigated in corneas irradiated with UVB rays the expression of MMP‐9 was more pronounced than the expression of MMP‐2. Conclusion Comparing the effect of the same doses of UVA and UVB rays on the normal rabbit cornea, UVB rays /not UVA rays/ evoked the increased expression of MMPs in the corneal epithelium. To investigate the importance of these findings is the aim of our next study.

Screening of Biomarker Genes Activated by Irradiation of Ultraviolet B Rays in Mouse Lymph Node M10 Cells

When M10 cells derived from mouse lymph nodes were irradiated with the UVB lamp at a peak emission of 312 nm, the cell growth was suppressed in proportion to irradiation time (10-30 s) and cell apoptosis was also induced by the irradiation. Dynamic changes in 597 genes after exposing these cells to UVB irradiation were investigated by DNA array analysis using array membranes and a (33)P-labeling probe. After 2 h of irradiation, the gene expression in the cells was examined and compared with that in untreated cells. Radioactivity was analyzed using Array Gauge software. The data were further processed using software, EX-ARRAY, which was developed for extracting significant data from the results of 2 background-subtraction methods, i.e., global and local background subtraction. The number of genes suppressed under UV irradiation increased with irradiation time, while that of activated genes decreased. Finally, we confirmed 4 genes (HMG-14, CDX-2, MCP-3, and GRP-78) to be up-regulated and confirmed their activation by northern blot. We propose these genes as the new biomarkers of lymphocyte sensitive to UVB irradiation.

Targeted UVB phototherapy for psoriasis: a preliminary study

Excimer laser treatment for psoriasis has been associated with good results at a lower cumulative dose than narrowband ultraviolet (UV)B protocols. To examine the clinical performance of a new targeted UVB lamp (290-320 nm; BClear) in the treatment of plaque-type psoriasis, 28 consecutive patients attending a dermatology service were treated twice weekly with the UVB lamp for 6-18 sessions (median 10). UV doses were based on multiples of a predetermined minimal erythema dose (MED). MEDs ranged from 150 to 350 mJ/cm2; maximal dose was 8 MED. Mean cumulative fluence until remission was 12.63 J/cm2. The Psoriasis Severity Index (PSI) was measured every 2 weeks for 16 weeks. Mean PSI improvement during treatment peaked at 73% after 6 weeks, and declined to 63% at 16 weeks. At that point, 36% of the patients had a > 75% improvement in PSI, and 21% showed complete clearance. Targeted radiation with the UVB lamp is effective for the treatment of plaque-type psoriasis, requiring as few as six sessions and achieving moderately long remission. As treatment is selectively directed toward lesioned skin, normal surrounding skin is spared unnecessary radiation exposure.

Grain yield and quality of wheat under increased ultraviolet radiation (UV-B) at later stages of the crop cycle

SUMMARYThe increase of ultraviolet (UV-B) radiation could be a challenge for wheat production systems in Southern Chile, as in other areas. Previous reports have shown that increased UV-B radiation decreases wheat yield by affecting both grain number and grain weight. However, contrasting results have also been published showing no effect on wheat biomass and grain yield. In addition, little is known about the effect of higher UV-B radiation at particular periods of the crop cycle on grain quality traits. The objective of the present study was to evaluate grain yield, yield components and grain quality in response to increased UV-B radiation during key periods of yield component determination. Two experiments were carried out under field conditions in the Universidad Austral de Chile (latitude 39°62′S). Two spring wheat cultivars were exposed to two periods of supplemented UV-B radiation (280–320 nm): (i) between booting and anthesis,c. 20 days, and (ii) from 10 days after anthesis until physiological maturity,c. 40 days. Ultraviolet radiation was increased to levels of 3·8 and 4·9 kJ/m2/day in experimental years 1 and 2, respectively, by using UV-B lamps. At harvest, plants were sampled to quantify aboveground biomass, grain yield, grain number and average grain weight. In addition, protein and gluten concentration of grains were measured. Grain yield was not affected (P>0·05) by the UV-B increase at pre- or at post-anthesis treatments. Similar results were found for each yield component. In addition, grain protein and gluten concentration showed similar values in the increased UV-B and control treatments. Therefore, if increases in UV-B radiation take place during the latter stages of the crop cycle as is expected, the present results do not support the speculation that increases of UV-B radiation in Southern Chile will compromise wheat production systems.

Photostability of Octyl‐P‐Methoxy Cinnamate in O/W Emulsions and in SLNs Vehicled in the Emulsions

The photochemical degradation of the sunscreen p‐octyl‐methoxy‐cinnamate (OMC) was studied in different media: Finsolv TN (a fluid ester), O/W emulsion and gel‐emulsion. OMC photolysis was performed using an UVB lamp and the degradation kinetic was studied in presence of various initial concentration of the active. The study was performed comparing the naked to the SLNs form of the active and the experiments were monitored with HPLC/UV‐VIS apparatus. Results suggest that lower is the concentration of the UVB sunscreen in the formulations more pronounced is its photodegradation rate. In all the cases the inglobation of OMC into SLNs leads to an over additive UV‐blocking effect.

A Randomized Comparison of Selective Broadband UVB and Narrowband UVB in the Treatment of Psoriasis

UVB is widely used to treat psoriasis. Conventional broadband UVB lamps are less effective than narrowband UVB lamps, which have an emission peak at 311 nm. The long-term safety of narrowband UVB phototherapy is uncertain. "Selective" broadband UVB lamps, which have little emission <290 nm, are also available, but have not been adequately compared to narrowband UVB lamps. We performed a randomized comparison of narrowband UVB (TL-01 lamps) and selective broadband UVB (UV6 lamps) in 100 patients with psoriasis. The median number of exposures for clearance was 28.4 for TL-01 and 30.4 for UV6 (ratio of the medians 0.93; 95% confidence interval (CI) 0.80, 1.09; P=0.39). No significant difference was found in the proportion of patients achieving clearance: TL-01 56%, UV6 40% (odds ratio for clearance with TL-01 relative to UV6 was 2.00 (95% CI 0.87, 4.62), P=0.10). Side effects, including the development of erythema during phototherapy, were similar for the two lamp types. Risk estimates based on the human photocarcinogenesis action spectrum predict that narrowband UVB lamps will be 50% more carcinogenic for equal erythemal doses than selective broadband lamps (UV6). As these two lamp types appear to be of similar efficacy, phototherapy using a selective broadband source may be a safer option than use of narrowband UVB.

Susceptibility to UV-A and UV-B Provocation Does Not Correlate With Disease Severity of Polymorphic Light Eruption

To examine whether the ease of disease provocation by UV-A and/or UV-B radiation correlates with clinical features of polymorphic light eruption (PLE), including those indicative of disease severity. Intervention study. One hundred forty-three patients with PLE. Provocation testing with broadband UV-A and UV-B lamps. Additionally, a range of clinical characteristics of the disorder, including a 5-item PLE severity score, was assessed by questionnaire. Percentage of PLE rash induction by UV-A and UV-B provocation, differences between the skin types, and correlation between the results of provocation and a range of clinical characteristics of the disorder, including a 5-item PLE severity score. Rash provocation was seen in 78.3% of patients after UV-A and in 46.7% after UV-B exposure. Neither UV-A nor UV-B provocation showed a significant association with the total 5-item severity score. The UV-B reactivity was associated with a high score on the severity item "number of months affected per year" (P = .04), whereas UV-A responsiveness showed a tendency for association with facial involvement (P = .06). The objective assessment of UV-A or UV-B susceptibility in this large group of patients showed no significant relationship with clinical disease severity.

충전층 반응기와 고정화 TiO2/UV를 이용한 Rhodamine B의 광촉매 탈색

The photocatalytic decolorization of Rhodamine B (RhB) was studied using packed-bed reactor and immobilized <TEX>$TiO_2/UV$</TEX> System. The 20 W UV-A, UV-B and UV-C lamps were employed as the light source. The effect of shape and surface polishing extent of reflector, distance between the reactor and reflector, reactor material were investigated. The results showed that the order of the initial reaction constant with reflector shape was round > polygon > W > rhombus. The optimum distance between the reactor and reflector was 2 cm. The initial reaction constant of quartz reactor was 1.46 times higher than that of tile PVDF reactor.

Time course of tanning induced by narrow‐band UVB phototherapy in Korean psoriasis patients

Narrow-band (TL-01) UVB lamps are being increasingly used for phototherapy in cases of psoriasis and other dermatoses due to the excellent results obtained. However, in Korea many patients receiving phototherapy have complained about the tanning effect of ultraviolet radiation. The aim of this study was to determine the time-course of pigmentation induced by phototherapy during and after narrow-band UVB treatment. Changes in skin color were recorded during phototherapy in 40 patients and after treatment in 20 patients. All patients were Korean and were evaluated during 10 weeks of phototherapy (three sessions per week), and then weekly post-phototherapy using two different reflectance spectrophotometers for 10 weeks. Results are presented as erythema (E)- and melanin (M)-indexes and as L*a*b* values as recommended by the Commission Internationale de l'Eclairge and individual typology angle (ITA). L* values, which indicate luminance, decreased continuously over the 5 weeks of phototherapy and showed a plateau after 5 weeks of treatment, and then slowly recovered over 10 weeks of post-treatment observation. Patterns of a* and b* values were comparable with L* values both during and after therapy. Mean ITA values also showed a pattern similar to L* values. E and M indexes changed slowly both during and post-phototherapy. In addition, when data were analyzed by skin type, the different skin types showed temporal patterns similar to the overall skin values, but the L* values and ITA and M indexes of skin type III recovered faster than those of skin types IV or V. This study shows that pigmentation induced by narrow-band UVB phototherapy increases continuously during the therapy and that recovery requires 10 weeks or more.

Simulation of Ozone Depletion Using Ambient Irradiance Supplemented with UV Lamps

In studies of the biological effects of UV radiation, ozone depletion can be mimicked by performing the study under ambient conditions and adding radiation with UV-B lamps. We evaluated this methodology at three different locations along a latitudinal gradient: Rimouski (Canada), Ubatuba (Brazil) and Ushuaia (Argentina). Experiments of the effect of potential ozone depletion on marine ecosystems were carried out in large outdoor enclosures (mesocosms). In all locations we simulated irradiances corresponding to 60% ozone depletion, which may produce a 130-1900% increase in 305 nm irradiance at noon, depending on site and season. Supplementation with a fixed percentage of ambient irradiance provides a better simulation of irradiance increase due to ozone depletion than supplementation with a fixed irradiance value, particularly near sunrise and sunset or under cloudy skies. Calculations performed for Ushuaia showed that, on very cloudy days, supplementation by the square-wave method may produce unrealistic irradiances. Differences between the spectra of the calculated supplementing irradiance and the lamp for a given site and date will be a function of the time of day and may become more or less pronounced according to the biological weighting function of the effect under study.