Increased expression of Fas on human epidermal cells after in vivo exposure to single-dose ultraviolet (UV) B or long-wave UVA radiation

BACKGROUND: Apoptosis has been proposed to act as an important mechanism for eliminating keratinocytes that have been irreversibly damaged by ultraviolet (UV) irradiation. One way to induce apoptosis in keratinocytes is through activation of the cell surface receptor Fas (CD95), either with the ligand (FasL) or directly with UV radiation. OBJECTIVES: To investigate the regulation of Fas and FasL expression in human skin and the formation of apoptotic cells after in vivo exposure to UVB or long-wave UVA radiation. METHODS: Volunteers were irradiated with either 3 minimal erythema doses (MED) of UVB (n = 6) or 3 MED of long-wave UVA (n = 6) on buttock skin 12, 24 and 72 h before skin punch biopsies were taken. Expression of Fas and FasL was demonstrated by immunohistochemistry on cryostat sections. Apoptosis was assessed by the terminal deoxynucleotidyl transferase-mediated fluorescein-deoxyuridine triphosphate nick-end labelling reaction. RESULTS: In five of six subjects, exposure to UVB radiation resulted in increased homogeneous expression of Fas on epidermal cells, with greatest expression at 24 and 72 h after irradiation. In all subjects, exposure to long-wave UVA resulted in increased homogeneous expression of Fas on epidermal cells, with greatest expression at 12 h after irradiation. In five of six subjects, exposure to UVB radiation resulted in temporarily decreased expression of FasL, but after 72 h the expression of FasL had returned to the preirradiation level. The expression of FasL on epidermal cells after exposure to long-wave UVA showed considerable variation. UVB irradiation was a stronger inducer of epidermal apoptosis than was UVA irradiation. The number of apoptotic epidermal cells did not correlate with expression of Fas or FasL. CONCLUSIONS: In human skin the expression of Fas on epidermal cells increases after in vivo exposure to UVB or long-wave UVA. Exposure to UVB causes a temporary decrease in the expression of FasL on epidermal cells.     

Pentoxifylline reduces the formation of sunburn cells

Abstract Irradiation with ultraviolet (UV) B light results in the formation of apoptotic keratinocyles called sunburn cells (SC). Although generation of SC appears to be one of the most characteristic features of UV-induced skin damage and has been a well-known phenomenon for a long time, the mechanisms involved are not quite clear. Recently, it was demonstrated that tumor necrosis factor α (TNFα) appears to be involved in the formation of SC since neutralization of TNFα both in vitro and in vivo reduced UVB-induced apoptosis of keratinocytes. Pentoxifylline is a methylxanthine derivative suppressing the release of TNFα. Therefore, we studied whether PTX is able to prevent the formation of SC. Addition of PTX to UVB-exposed HaCaT cells reduced DNA-fragmentation as examined by nick translation evaluated by floweytometry. To prove whether PTX also reduces UVB-induced apoptosis in vivo. BALB/c mice were exposed to UVB on their abdomens, skin biopsies performed 24 h later and SC counted. A single dose of 2000 J/m² caused a significant induction of SC which were remarkably reduced when PTX was injected intraperitoneally 3 h before and 12 h after UVB exposure. In summary, the data demonstrate that PTX can reduce the formation of SC both in vitro and in vivo and thus further support that TNFα is involved in UVB-induced apoptosis of keratinocytes.     

A sun holiday is a sunburn holiday

Many people take holidays in sunny locations with the express aim of sunbathing. This may result in sunburn, which is a risk factor for skin cancer. We investigated 25 Danish sun seekers during a week's holiday in the Canary Islands. The percentage of body surface area with sunburn was determined by daily skin examinations by the same observer. Erythemally effective ultraviolet radiation (UVR) exposure was assessed with time‐stamped personal dosimeters worn on the wrist. Volunteers reported their clothing cover and sunscreen use in diaries, and this information was used to determine body site‐specific UVR doses after adjustment for sun protection factor. Remarkably, we found that all volunteers sunburned at some point. The risk of sunburn correlated significantly with the adjusted body site‐specific UVR dose. Furthermore, there was also a significant relationship between the daily UVR dose and percentage of body surface area with sunburn. Our study shows that holiday UVR exposure results in a high risk of sunburn, which potentially increases the risk of skin cancer. Possible protection by melanogenesis is insufficient to protect against sunburn during a 1‐week sun holiday. Finally, our data clearly support a substantial skin cancer risk from sun holidays.     

Field-based measurements of personal erythemal ultraviolet exposure through a common summer garment

The research in this paper quantifies the solar erythemal UV exposures to the skin through a common summer garment during outdoor activities. The erythemal exposures under the garment for the wet white garment exceeded a MED (minimum erythemal dose) at some anatomical sites in summer for a two-hour period. An erythemal exposure of 1.7 MED, in excess of the occupational limit for UV exposure, was measured under the white garment during swimming for a one-hour period. Clothing must form an important component of a UV protection strategy. However, it must be realised that total UV protection is not provided and significant UV exposures may be received beneath the garment, particularly for a white garment in the wet state. This re-enforces the necessity of a combination of several UV prevention strategies to minimise UV exposure.     

Can ultraviolet erythema be used to identify the basal cell carcinoma phenotype?

Since a prolonged duration of a strong UBV erythema has been suggested as a marker for propensity to develop skin cancer, we objectively followed the duration and intensity of erythemas induced by UVB and UVA radiation for 28 days in 18 patients with basal cell carcinoma (BCC), and in 15 healthy controls using reflectance spectrophotometry. The erythema index, defined as the difference in redness between UV-exposed skin and normal, adjacent skin on the lower abdomen, did not differ significantly between the two groups at 24 h, when the reaction was maximal, following a dose of 6 MED of UVB. Erythema values after 7 and 14 days were slightly higher in the BCC group, but this difference did not reach statistical significance. At day 7 some patients in the BCC group showed very strong erythemas. At days 21 and 28 the two groups had almost identical erythemal reactions. Following a standard dose of UVA of 100 J/cm², patients with BCC and healthy controls both showed weak erythemal reactions, which declined somewhat over the study period. No significant differences in pigmentary response were noted between the BCC and the control group, neither following UVB nor UVA. Although individual patients with BCC deviate from the normal erythemal curve for UVB, the UVB response is not a suitable predictive instrument in screening patients with the basal cell carcinoma phenotype.     

Recurrent recall of sunburn by methotrexate

An unusual recall reaction of sunburn with methotrexate use has been previously reported. Heretofore, all reports have documented a single occurrence of this reaction in each patient. We report, for the first time, a patient who developed recurrent facial sunburn recalls while receiving methotrexate for psoriasis. This reaction is distinct from true photosensitivity. Photosensitivity is listed in the drug brochure for methotrexate. However, a review of the literature does not support true photosensitivity associated with methotrexate.     

Effect of childhood and adolescent ultraviolet exposures on cumulative exposure in South East Queensland schools

Quantitative estimates of the childhood and adolescent erythemal ultraviolet (UV) exposure received in South East Queensland schools are provided in this paper for age groups 0 to 6, 7 to 12 and 13 to 19 years. For the neck, hand and lower arm, sites of high UV exposure that are generally not covered by clothing, 13 to 19 year olds received the highest exposure of the three age groups, followed by 7 to 12 year olds. Exposure for 13 to 19 year olds contributed up to 44% of cumulative exposure to 20 years of age, and exposures for the 7 to 12 year olds contributed up to 31%. If the annual UV exposure for these two age groups were reduced to the average of all the age groups, cumulative erythemal UV exposure from 0 to 20 years would be reduced by up to 16%. On the other hand, if mothers can protect their babies by reducing the level of annual exposure to 30% of the annual UV exposure of the 7 to 12 year olds for the first four years then cumulative exposure to UV to age 20 would be reduced by up to 19%. These data confirm the importance of targeting young age groups in public campaigns for sun protection.     

Reduction of the erythema response to ultraviolet light by nonsteroidal antiinflammatory agents

Summary The effect of three nonsteroidal antiinflammatory agents (NSAIA) on ultraviolet B (UV-B)-induced erythema was studied in normal human volunteers. Aspirin, indomethacin, and ibuprofen were administered orally 2 h before exposure to UV-B from fluorescent sunlamps and at 4-h intervals for a total of four doses. The minimal dose of light to produce erythema (MED) was determined for each subject with and without drugs. There was a 240% increase in the mean MED when the NSAIA were given. NSAIA, given orally, can increase the threshold for UV-B-induced erythema when administered near the time of irradiation.     

The effects of body size and orientation on ultraviolet radiation exposure

A method has been developed for determining the UV and erythemal exposures to the entire body. The difference between the ambient erythemal exposure and that to the body compared to the ambient exposure may be as high as 76%. The height, orientation, and overall height had a minimal effect on the exposure to the body with size, time of day and time of year having a significant effect. The diffuse component of UV to a side of the body ranged from 20% to 41% between different times of the year with different levels of cloud cover. The ratio of the body to the ambient erythemal exposures varied from 0.24 to 0.61, with the time of day and time of year with the smaller value for periods of high solar altitude.     

A preliminary investigation into the effect of exposure of photosensitive individuals to light from compact fluorescent lamps

Summary Background  Compact fluorescent lamps (CFLs) are due to replace common incandescent lamps over the next few years. There has been no investigation of the possible effect of this on patients with photosensitive disorders. Objectives  To determine the effect of exposure of photosensitive individuals to light from CFLs. Methods  The spectral emission from a sample of CFLs was measured using a calibrated spectroradiometer. The erythemal response was determined in one normal individual and four photosensitive individuals by direct exposure of the skin to light from a CFL. The susceptibility of a wider group of photosensitive individuals was predicted based on the light dose known to elicit a reaction during phototesting at discrete ultraviolet (UV) wavelengths. Results  CFLs emit UV radiation at wavelengths down to 254 nm. Prolonged exposure of a normal individual’s skin produced erythema. However, an exposure of only 2·5 min at 5 cm elicited marked erythema in one of the abnormally photosensitive patients. Conclusions  CFLs could be a source of harmful UV radiation to photosensitive individuals. Patients with chronic actinic dermatitis are thought to be at greatest risk. The use of a protective envelope is recommended.     

Effect of pentoxifylline on sunburn cell formation in a novel supravital human skin model

BACKGROUND/AIM: The aim of this study was to determine whether pentoxifylline (Pf) has an effect on sunburn cell (SBC) formation in humans. METHODS: A novel supravital human skin model was used. Normal skin samples were placed on gauze in completed RPMI 1640 Medium and remained vital for 48 h. Three concentrations of Pf (7.5, 15.0 and 30.0 microg/ml) were tested. After 2 h, each skin sample was irradiated with 120 mJ/cm2 of UVB. After 24-h incubation, the samples were formalin fixed, paraffin embedded and sections were stained with haematoxylin-eosin. RESULTS: The mean count of SBC (10.43 +/- 1.35 (SEM)) was significantly higher in the control group (without Pf) compared with its mean count in 7.5 microg/ml Pf (5.18 +/- 0.62, P < 0.001), or 15.0 microg/ml Pf (5.79 +/- 1.70, P < 0.001), or 30.0 microg/ml Pf (4.37 +/- 1.47, P < 0.001). CONCLUSION: Pentoxifylline reduced SBC formation in our supravital human skin model. It presumably acts as an antioxidant agent.     

Timing of excessive ultraviolet radiation and melanoma: epidemiology does not support the existence of a critical period of high susceptibility to solar ultraviolet radiation- induced melanoma

BACKGROUND: The existence of a 'critical period' early in life characterized by a high susceptibility to melanoma initiation due to excessive ultraviolet (UV) radiation has been suggested by various authors based on epidemiological findings from migration studies and some case-control studies. However, the evidence so far is controversial as several epidemiological investigations failed to corroborate these results. Objective To compare the increase in melanoma risk due to excessive UV radiation between different periods in life. METHODS: In a multicentre case-control study we recruited 603 melanoma cases and 627 population controls in seven European countries. We obtained data on the history of sunburns during 'childhood' ( 15 years), respectively, in standardized personal interviews. We employed logistic regression analyses to estimate the impact of the exposure factors under study, while simultaneously controlling for the effect of a variety of confounding variables. RESULTS: We found a very similar upward gradient of melanoma risk in exposure categories related to the frequency of sunburns during both periods in life. More than five sunburns doubled the melanoma risk, irrespective of their timing in life. CONCLUSIONS: Our data do not provide supporting evidence for the existence of a 'critical period'. The hazardous impact of sunburns seems to persist lifelong and thus activities concerned with melanoma prevention should be directed to the entire population rather than being focused only on younger age groups.     

The minimal melanogenesis dose/minimal erythema dose ratio declines with increasing skin pigmentation using solar simulator and narrowband ultraviolet B exposure

Purpose: To investigate the relation between pre‐exposure skin pigmentation and the minimal melanogenesis dose (MMD)/minimal erythema dose (MED) ratio after a single narrowband ultraviolet B (nUVB) and solar simulator (Solar) exposure. Background: In fair‐skinned individuals, it is well known that the UV dose to give pigmentation (MMD) after a single exposure to UVB is larger than the UV dose to elicit erythema (MED) (MED<MMD), but it remains to be established if this is true also in dark‐skinned individuals. Methods: Eighty‐four volunteers with a wide variation in skin pigmentation (Fitzpatrick skin types I–V) were included. Results: After a single Solar or nUVB exposure we found that the ratio MMD/MED depends on skin pigmentation. In light‐pigmented individuals, up to 1.9 MED is required to induce pigmentation (MMD). The MMD/MED ratio is about 1.5 in medium‐pigmented and dark‐pigmented individuals. In very brown‐pigmented individuals the MMD/MED ratio is 1 (MED=MMD). This connection was most pronounced for facultative skin at wintertime. The ratio was almost stable for constitutive pigmentation with MMD/MED=1.3. The ratios were almost independent of skin type. Conclusion: The ratio MMD/MED is highly dependent on skin pigmentation after a single exposure to Solar or nUVB and is independent of skin type.     

多形性日光疹患者紫外线最小红斑量测定

UVA和UVB均能引起光变态反应[1-2].为证实紫外线与多形性日光疹(PMLE)之间是否有相关性,我们测定了PMLE患者UVA、UVB的最小红斑量(MED).     

Effect of stretch on the ultraviolet spectral transmission of one type of commonly used clothing

The spectral ultraviolet (UV) transmission through stockings was measured in field and laboratory based trials using a spectroradiometer. From these spectral UV measurements, the ultraviolet protection factor (UPF) was calculated. The UPF of stockings measured in the field was generally higher than that measured in the laboratory when using a quartz tungsten halogen light as the UV source. The UPF of 50 denier stockings decreased 868% when stretched 30% from their original size. Doctors recommending and patients using high denier stockings for patient photoprotection should be aware of the dramatic decrease in UPF when the stocking is in a stretched position, such as over a human leg.     

Human exposure to solar ultraviolet radiation

Solar ultraviolet (UV) irradiation depends upon the local UV climate, people's behaviour. Behaviour includes the time spent outdoors and the use of photoprotective agents. In adult life, a British indoor worker in the UK might typically receive 30% of his or her annual UV exposure from sun-seeking holidays, 40% from summer weekends, 20% from casual weekday exposure between April and September and just 10% from sun exposure during the 6 month period October to March. Whilst climatic factors do influence levels of UV radiation (UVR) at the Earth's surface, it is people's behaviour out of doors that has a much greater impact on personal solar UV irradiation. Methods of personal protection include: avoiding direct sunlight in summer around noon; seeking the shade; wearing clothing absorbs UVR; wearing hats that shade face and neck; and using topical sunscreens.     

Persistent polymorphous light eruption after ultraviolet A1 phototherapy

Polymorphous light eruption (PMLE) is the most common photodermatosis and is characterized by the development of a pruritic skin eruption within a few hours to days after sun or artificial light exposure. The eruption usually takes up to two weeks to resolve in the absence of further ultraviolet radiation. PMLE has been reported as a side effect of ultraviolet A1 (UVA1) therapy but characteristics of the eruption, especially the duration until resolution after treatment, has not been described. A 37‐year‐old female developed an unusually persistent PMLE that lasted for 5 weeks after completion of UVA1 phototherapy.     

Change in ultraviolet (UV) transmission following the application of vaseline to non-irradiated and UVB-exposed split skin

BACKGROUND: Topical preparations such as emollients used in combination with phototherapy can interfere with such treatment. OBJECTIVES: This study was performed to investigate the impact of vaseline on the ultraviolet (UV) transmission of non-irradiated split skin and on split skin previously exposed to UVB radiation. METHODS: Split-skin specimens were obtained from 20 patients. In each case, one sample was taken from an area of non-irradiated skin, while the second was taken from an area that had been previously exposed to UVB. The transmission was spectrophotometrically measured with split skin placed in specially designed quartz glass cuvettes before and after the application of two different amounts of vaseline (2.5 and 17.5 mg cm-2). RESULTS: Application of vaseline to skin previously exposed to UVB caused significant (P < 0.0001) changes in UV transmission in certain wavelength ranges. In the UVA range, a greater increase in transmission was achieved with 2.5 mg cm-2 vaseline, whereas in the UVB range, a greater increase was achieved with 17.5 mg cm-2 vaseline. The thicker the layer of vaseline applied, the lower was the difference in transmission between non-irradiated split skin and UVB-exposed split skin. CONCLUSIONS: Application of the correct amount of vaseline can enhance transmission in either the UVA or UVB range, and would enable dose reduction during a course of phototherapy.