Comparison of the erythemogenic effectiveness of ultraviolet-B (290-320 nm) and ultraviolet-A (320-400 nm) radiation by skin reflectance

Preemptive treatment with Xonrid®, a medical device to reduce radiation induced dermatitis in head and neck cancer patients receiving curative treatment: a pilot study

PURPOSE

The purpose of this study was to investigate efficacy, safety and tolerability of Xonrid®, a new medical device, in preventing radiation dermatitis associated with head and neck cancer (HNC) radiotherapy (RT).

METHODS

In this monocentric, prospective pilot study, adult consecutive HNC patients who were planned to receive curative RT with or without chemotherapy were enrolled. Patients were instructed to apply Xonrid® on the irradiated area during treatment continuing until 2 weeks after the completion of RT or the development of severe skin toxicity. Toxicity was assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 4.0 scale. The patient reported outcome measures included the Skindex-16 questionnaire and patient satisfaction. Skin reflectance spectra were analyzed to objectively evaluate dermatitis.

RESULTS

In total, 41 subjects were enrolled (30 males, median age 60 years). No skin adverse events were recorded either in the skin area where the product was applied or in the nearby skin over the entire period of administration. At the end of RT, nine patients (22%) presented G1, 31 (76%) G2, and one patient (2%) G3 skin toxicity (after 5 weeks). Seven and 20 patients reached skin maximum toxicity at the fourth week and after the seventh week, respectively. An increasing trend of median spectrophotometry scores along with skin toxicity grades was observed. A correlation between Skindex-16 scores and skin toxicity grade during treatment was found.

CONCLUSIONS

Our study results suggest that Xonrid® is well tolerated, safe, and effective in minimizing and delaying high-grade radiation dermatitis in HNC patients.

Objective measurements of radiotherapy-induced erythema

BACKGROUND/AIMS

The development of acute radiation erythema is a common phenomenon among patients under-going radiotherapy treatment. Because of the absence of reliable objective classification methods, the degree of skin reaction can at present mainly be judged subjectively in the clinic. This has motivated the present preliminary study,concerning the first steps in the development of an objective method for skin reaction classification.

METHODS

Three non-invasive techniques were used:near-infrared (NIR) spectroscopy, laser Doppler perfusion imaging and digital photography. The NIR spectra were analysed with principal component analysis (PCA), and the results from the other two with traditional univariate methods. Measurements were made on breast cancer patients who had been exposed to different irradiation doses. A total of 28 breast cancer patients participated one to three times each; 12 were treated with photons at 4 or 6MeV and 16 were treated with high-energy electrons between 10 and 20 MeV to a maximum dose of 50 Gy.

RESULTS

PCA of NIR spectra shows that information on radiation dose lies mainly in the first principal component. It is observed that the higher the dose the higher the score value. The results from the laser Doppler measurements show that in 79% of the cases the perfusion increases significantly with radiation dose. Analysis of the digital photography shows that a proposed skin redness index(SRI), increases with a higher radiation dose. However,the increase in most cases is not significant. By combining all data, correlation to radiation doses was seen for 74% of the patients who participated more than once.

CONCLUSION

All three non-invasive methods correlate with the radiation dose but to various degrees. NIR spectroscopy, laser Doppler and a combination of the three techniques are the most promising methods for characterising erythema.

Design and evaluation of a novel portable erythema-melanin-meter

BACKGROUND AND OBJECTIVES

Objective evaluation of the pigmentation index (PI) and the eythema index (EI) of human skin is a prerequisite for successful optimization of laser- and intense-pulsed-light (IPL)-based treatment modalities in dermatology.

STUDY DESIGN/MATERIALS AND METHODS

We describe a three-wavelength technique for determining PI and EI as well as its particular implementation using LEDs operating at wavelengths of 560, 650, and 710 nm and a large-area photodiode. The instrument has been evaluated both in vitro and in vivo.

RESULTS

In vitro, good correlation between the measured indices and results obtained with commercially available techniques has been observed. In addition, linearity of the PI with melanin concentration in the phantom medium up to 7 x 10(-3) nm(-1) (defined as a slope of the optical density spectrum) has been established. In vivo, feasibility of using the technique for predicting the minimal erythema dose (MED), minimal phototoxic dose (MPD), and the threshold of epidermal damage in a photothermal treatment has been demonstrated.

CONCLUSIONS

The data suggest that the technique has a substantial potential as a method of pre-treatment diagnostics for photochemical and photothermal procedures.

Skin irritation in man: a comparative bioengineering study using improved reflectance spectroscopy

Variable types of skin irritation were induced in 8 human female volunteers, ranging from subclinical to visible erythema with slight oedema. Skin reactions were graded clinically and objectively using transepidermal water loss (TEWL), laser Doppler flowmetry (LDF) and improved reflectance spectroscopy. This last technique enables separation of in vivo erythemas into relatively deoxygenated (venous--deoxy hem) and oxygenated (arterial--oxy hem) haemoglobin components. Compared to uninvolved skin, an empty patch increased oxy hem by 197% +/- 121% (p < 0.05). Exposure to vehicles also changes skin biophysics. At sodium lauryl sulfate (SLS) and hydrochloric acid (HCl) exposed sites, a linear correlation between concentration and oxy hem, LDF and TEWL was found. These chemicals predominantly increased TEWL values. Nonanoic acid (NON) and imipramine (IMI) also raised oxy hem, LDF and TEWL values linearly at increasing concentrations. Although IMI 2.5% clinically was graded as a type ++ response, no significant increase in TEWL was found. The improved reflectance spectroscopic technique proved valid in skin irritation studies, with a higher sensitivity than laser Doppler flowmetry, and allowed irritant vascular reactions to be discriminated into arterial and venous components. Furthermore, our observations clearly demonstrate that clinically indistinguishable skin irritation reactions induce significantly different changes in barrier function (disruption) and vascular status.

On the induction of protective responses in Salmonella typhimurium strain TA1535/pSK1002 by UVA (365 nm)

Exposure to UVA (365 nm) led to growth delay, loss of viability and inhibition of 3H-thymidine incorporation into the cells of Salmonella typhimurium strain TA1535 containing multiple copies of a plasmid pSK1002 carrying a umuC'-'lacZ fusion gene. Ultraviolet-A induced umu gene expression, as monitored by the estimation of beta-galactosidase, in a linear fluence-dependent manner. The induction of umu gene expression increased with the increase of postirradiation incubation period of the cells in the LB-ampicillin (LBA) medium at 37 degrees C and leveled off from 2 h onward. The induction of gene expression depended on concomitant protein synthesis and represented the induction of the SOS response in the particular S. typhimurium cells used. The exposure to low fluences (sublethal) of UVA also led to the induction of an adaptive response in the same bacterial cells, which made them resistant to subsequent challenge by a much higher fluence of the same radiation. The adaptive response, as monitored by the assays of viability and beta-galactosidase units, increased with the period of exposure to sublethal fluences of UVA, attained a maximum at the UVA exposure of 4.5 kJ/m2 (15 min) and thereafter gradually decreased with further increase of UVA exposure period. Modulation studies involving D2O, LBA growth medium, different scavengers of free radicals and quenchers of activated oxygen species indicated the involvement of both hydroxyl free radicals and singlet oxygen in the UVA-induced umu gene expression.

Action spectrum for erythema in humans investigated with dye lasers

Erythema reactions of human skin were reevaluated with improved experimental methods: a tunable, highly monochromatic irradiation source as well as an instrumental measurement of skin reactions were used. The irradiation system consisted of an excimer laser pumped dye laser and a UV fiber optic system. The skin color after irradiation was determined with a colorimeter in the three-dimensional norm system of the Commission Internationale d'Eclairage (CIE). The wavelength dependence for delayed erythema was investigated in the UVB and UVA region from 294 nm to 374 nm in skin type II and III individuals. The maximum of the action spectrum in the UVB range was measured at 298.5 nm and an additional maximum was found at 362 nm in the UVA range. The action spectrum is compared with previous spectra from the literature and with the current standard erythema curve of the CIE as well as with other photobiological action spectra. Our results suggest a UVA/UVB boundary at 330 nm.

UVA-induced peroxidation of lipid in the dried film state

Exposure of a dried lipid thin film to UVA produced a dose-dependent linear increase in the three peroxidation products, conjugated diene, lipid hydroperoxide and malondialdehyde (MDA). All three lipid peroxidation products exhibited an inverse dose rate effect. Identical amounts of malondialdehyde were produced when the lipid film was exposed to UVA either directly or through the thickness of the Corning glass on which the film was cast. Antioxidants, alpha-tocopherol, butylated hydroxytoluene (BHT) and the singlet oxygen quencher beta-carotene significantly inhibited the UVA-induced peroxidation of the lipid film. The biological implications of the UVA-induced peroxidation of the dried lipid film are discussed.

Quantification of patient to patient variation of skin erythema developing as a response to radiotherapy

A method is described to determine accurately skin redness during a course of radiotherapy using reflectance spectroscopy utilizing information from across the visible spectrum according to the L*a*b* color coordinate system. The method was used to quantify the development of skin erythema during and after electron beam irradiation of the chest wall following mastectomy. A number of factors were identified which could influence the wide variation in response seen between patients. These were: intra- and inter-observer variation; intra- and inter-patient variation and variation in the actual dose delivered. Statistical analysis, including an analysis of variance of inter- and intra-patient variation, revealed that the major factor that accounts for the observed difference between patients is a true inter-patient variation, with a coefficient of variation, corrected for intra-patient variation, of 43%. Within the narrow dose range administered in this study, there was no demonstrable dose-effect relationship, raising questions about the role of cell death in the basal layer of the epidermis in the pathogenesis of radiation induced erythema.

A computerized autofluorescence and diffuse reflectance spectroanalyser system for in vivo skin studies

A microcomputer-controlled spectroanalyser system has been set up to study optical properties of normal and abnormal human skin in vivo. The system can measure both tissue autofluorescence and diffuse reflectance at selected skin locations. The sample holder allows adjustment of the incident angle of the illumination light and the pick-up angle of the collected light providing the means to examine different depths of skin tissue. Using this system, we detected measurable skin autofluorescence with a maximum at about 470 nm when excited with 380 nm UV radiation. In this work, we also show that the absorption and scattering properties of the skin tissue (which can be determined from the measured diffuse reflectance spectrum) affect the shape of the autofluorescence spectrum. We believe that the combination of autofluorescence and diffuse reflectance measurements will lead to better understanding of the optical properties of normal and abnormal skin tissue.

The comparison of sun protection factor values with different light sources

Sun protection factors (SPFs) were evaluated with three light sources (sunlight, a xenon arc solar simulator, and fluorescent lamps) in indoor and outdoor studies. Two types of light, UV-A+B and UV+Visible, were obtained from the solar simulator. The untanned backs of twenty-four healthy male volunteers were used as test sites. A broad spectrum sunscreen containing SPF 6, according to the manufacturer, was used. The sunscreen tested was applied at 2 mg/cm2. The actual SPF values were 4.8 with sunlight, 6.0 with UV-A+B, 4.9 with UV+Visible, and 11.8 with fluorescent lamps. There were no significant differences between the SPF values with sunlight and those with the solar simulator; the SPF value for fluorescent lamps was significantly higher. The SPF with UV-A+B of the solar simulator was similar to that with sunlight; the use of this light served to reduce pain on tested subjects. Therefore, UV-A+B from the solar simulator seems to be the most appropriate artificial light source for evaluating sunscreens.

In vivo evaluation of photoprotection against chronic ultraviolet-A irradiation by a new sunscreen Mexoryl SX

In a previous study on the hairless mouse it was shown that sub-erythemal doses of pure UV-A enhanced the numerous changes normally observed during chronological aging. A new sunscreen (a bis-benzylidene campho sulfonic acid derivative) has been synthesized in our research laboratory (lambda max: 345 nm, epsilon: 47,000). Its photoprotective properties against UV-A induced damages were assessed in our mouse model. Three month old albino hairless mice were exposed for 1 y to suberythemal doses (35 J/cm2) of UV-A obtained from a xenon source filtered through a WG 345 filter. One group of animals was exposed untreated, the other received a formulation containing 5% of the sunscreen prior to irradiation. At the end of the study the cutaneous properties of protected mice were compared to those of unprotected animals and to 3 and 15 month old unirradiated controls. We found that the visible changes induced by UV-A irradiation were mainly sagging and wrinkling. Histological and electron microscopic alterations consisted of hyperkeratosis, increased density of elastic fibers with alteration of fiber orientation and increased glycosaminoglycan deposits. Biochemical changes consisted of decreases in total collagen and collagen hydroxylation and increases in both collagen III/I + III ratio and fibronectin biosynthesis. All these changes were reduced or abolished by the sunscreen.

An animal model for evaluation of topical photoprotection against ultraviolet A (320-380 nm) radiation

Recent studies reporting UVA (ultraviolet A radiation 320-380 nm) as an integral part of the cumulative sun-induced damage in human skin have prompted an interest in developing effective UVA photoprotective agents. The development of such compounds has been impeded by the absence of a clinically relevant animal model for evaluating their efficacy. This report describes the development and use of such a laboratory animal system. Selected concentrations of oxybenzone (2-hydroxy-4-methoxybenzophenone) in vehicle (0.1% to 6%) or vehicle alone were applied to the depilated dorsal skin of 30 Hartley strain female albino guinea pigs. The skin was irradiated with solar simulated UVA from a xenon light source. Acute radiation-induced damage was assayed by erythema grading and inhibition of [3H]thymidine incorporation into epidermal DNA. Data from erythema grading studies indicated that a significant degree of photoprotection was achieved with 6%, 3%, and 1% solutions of benzophenone compared with the control vehicle; the 6% solution was significantly more photoprotective than the 3% and 1% solutions. A 6% solution afforded significant photoprotection when assayed by [3H]thymidine incorporation.

Quantitative studies on UVA-induced erythema in human skin

The erythemal response of normal human skin to UVA and UVB radiation was measured objectively using a reflectance instrument in seven subjects, and a laser Doppler velocimeter in two subjects. UVA radiation was produced using a newly-developed high-intensity UVA lamp. The slope of the log dose-erythemal response curve for UVA at 24 h after irradiation was found not to differ significantly from that for UVB. The time course of UVA erythema was biphasic; erythema was present immediately after irradiation, fell to a minimum at about 4 h and then rose to a broad plateau between 6 and 24 h. The intensity of the early phase was dose-rate dependent, whereas that in the later phase depended on dose only.

A portable instrument for quantifying erythema induced by ultraviolet radiation

The design and performance of an instrument for quantifying ultraviolet-induced cutaneous erythema are discussed. If the instrument is used to record an 'erythema index' at a site on the skin before and after irradiation, the difference between those two readings is essentially related to an increase in vasodilation and is largely independent of the melanin content of the epidermis.

Quantitative studies on cutaneous erythema induced by ultraviolet radiation

A reflectance instrument was used to measure the variation in UVR-induced erythema at different positions on the back. The pre-irradiation erythema index decreased from top to bottom of the back but the increase in index remained constant for a fixed exposure dose. In contrast, the minimal erythema dose was higher at lower sites on the back. The measured erythemal response increased linearly with the logarithm of the radiation dose from approximately the minimal erythema dose up to at least fifteen times this value.

Quantitative assessment of UV-induced changes in microcirculatory flow by laser Doppler velocimetry

Objective measurements of blood flow changes following UV irradiation in the skin of human volunteers have been made with the noninvasive technique of laser Doppler velocimetry (LDV). This optical procedure allowed perfusion (number of red cells X velocity) alterations in the cutaneous microcirculation to be monitored after exposure of the skin to UVA and UVB + UVC radiation. Response curves were obtained in 6 subjects following irradiation at 4 times the minimal UVB + UVC erythema dose (MED). Measurements were made on control (untreated) skin and on skin pretreated with a sunscreen lotion. It was found that: (1) the lotion vehicle had no protective effect, (2) the active sunscreen constituent (2-ethylhexylcinnamate, 5%) was significantly protective, and (3) the presence of bergapten (5-methoxypsoralen, 30 ppm) did not enhance or diminish the cinnamate protective effect. LDV measurements in 5 subjects were also taken during and subsequent to 5 daily exposures to 1 MED of UVB + UVC radiation. Control and pretreated skin sites were again studied and similar protective effects were observed. However, on subsequent reexposure of these sites to 4 MED of UVB + UVC, 14 days after the first of the 5 single MED doses, no significant change in skin blood perfusion was detected at either control or pretreated sites. In a separate series of experiments, LDV data were collected after UVA radiation exposures up to 15 J/cm2. No changes in microcirculation perfusion were detected in any of the situations considered. All LDV measurements were made with 2 instruments of slightly different design and were compared to subjective assessments of erythema performed by a single observer. The results suggest that LDV has significant potential as a means to quantify (1) UV exposures in excess of the MED and (2) the inhibition of UV-induced changes in microcirculatory flow by chemical protectants.