Urinary thymidine dimer excretion reflects personal ultraviolet radiation exposure levels.

Exposure to ultraviolet radiation (UVR) leads to skin DNA damage, specifically in the form of cyclobutane pyrimidine dimers, with thymidine dimers being the most common. Quantifying these dimers can indicate the extent of DNA damage resulting from UVR exposure. Here, a new liquid chromatography-mass spectrometry (LC-MS) method was used to quantify thymidine dimers in the urine after a temporary increase in real-life UVR exposure. Healthy Danish volunteers (n = 27) experienced increased UVR exposure during a winter vacation. Individual exposure, assessed via personally worn electronic UVR dosimeters, revealed a mean exposure level of 32.9 standard erythema doses (SEDs) during the last week of vacation. Morning urine thymidine dimer concentrations were markedly elevated both 1 and 2 days post-vacation, and individual thymidine dimer levels correlated with UVR exposure during the last week of the vacation. The strongest correlation with erythema-weighted personal UVR exposure (Power model, r2 = 0.64, p < 0.001) was observed when both morning urine samples were combined to measure 48-h thymidine dimer excretion, whereas 24-h excretion based on a single sample provided a weaker correlation (Power model, r2 = 0.55, p < 0.001). Sex, age, and skin phototype had no significant effect on these correlations. For the first time, urinary thymidine dimer excretion was quantified by LC-MS to evaluate the effect of a temporary increase in personal UVR exposure in a real-life setting. The high sensitivity to elevated UVR exposure and correlation between urinary excretion and measured SED suggest that this approach may be used to quantify DNA damage and repair and to evaluate photoprevention strategies.

Optics miniaturization strategy for demanding Raman spectroscopy applications.

Raman spectroscopy provides non-destructive, label-free quantitative studies of chemical compositions at the microscale as used on NASA's Perseverance rover on Mars. Such capabilities come at the cost of high requirements for instrumentation. Here we present a centimeter-scale miniaturization of a Raman spectrometer using cheap non-stabilized laser diodes, densely packed optics, and non-cooled small sensors. The performance is comparable with expensive bulky research-grade Raman systems. It has excellent sensitivity, low power consumption, perfect wavenumber, intensity calibration, and 7 cm-1 resolution within the 400-4000 cm-1 range using a built-in reference. High performance and versatility are demonstrated in use cases including quantification of methanol in beverages, in-vivo Raman measurements of human skin, fermentation monitoring, chemical Raman mapping at sub-micrometer resolution, quantitative SERS mapping of the anti-cancer drug methotrexate and in-vitro bacteria identification. We foresee that the miniaturization will allow realization of super-compact Raman spectrometers for integration in smartphones and medical devices, democratizing Raman technology.

Equipment developed for simplifying routine phototesting in dermatology.

Some people react abnormally when exposed to sunlight by getting easily burned or develop a rash. When testing a patient's level of photosensitivity in the clinic, the UVR dose to provoke erythema is determined by the minimal erythema dose (MED) test. Subsequently, a photoprovocation test is performed to detect abnormal skin reactions by daily exposing the skin to UVR for several consecutive days. Associated problems in MED testing include choice of an even skin area for testing, patients keeping still during the test, testing with different UVR doses simultaneously, and securing clear borders of erythema. To address these issues, a MED Test Patch was developed which adheres closely to the skin to ensure sharp erythema borders and provides six irradiation fields with decremental doses of 20%. For MED testing, we constructed a solar simulator and LED lamps with peak emissions at 309 and 370 nm, small enough to be mounted directly on to the MED Test Patch and accommodate patient movements. These lamps and a 415 nm LED can also be used for provocation testing which is best performed on the back where the skin is assumed to have identical UVR sensitivity, and the area is large enough for adjacent MED and provocation test fields. Reading of erythema is still performed by visual and tactile evaluation. The UVA and UVB MED test can be performed in 1 h. The advantage of these developments is an easy-to-use, standardized test method with improved accuracy of the results.

Comparison of global DNA methylation analysis by whole genome bisulfite sequencing and the Infinium Mouse Methylation BeadChip using fresh and fresh-frozen mouse epidermis.

Until recently, studying the murine methylome was restricted to sequencing-based methods. In this study we compared the global DNA methylation levels of hairless mouse epidermis using the recently released Infinium Mouse Methylation BeadChip from Illumina and whole genome bisulphite sequencing (WGBS). We also studied the effect of sample storage conditions by using fresh and fresh-frozen epidermis. The DNA methylation levels of 123,851 CpG sites covered by both the BeadChip and WGBS were compared. DNA methylation levels obtained with WGBS and the BeadChip were strongly correlated (Pearson correlation r = 0.984). We applied a threshold of 15 reads for the WGBS methylation analysis. Even at a threshold of 10 reads, we observed no substantial difference in DNA methylation levels compared with that obtained with the BeadChip. The DNA methylation levels from the fresh and the fresh-frozen samples were strongly correlated when analysed with both the BeadChip (r = 0.999) and WGBS (r = 0.994). We conclude that the two methods of analysis generally work equally well for studies of DNA methylation of mouse epidermis and find that fresh and fresh-frozen epidermis can generally be used equally well. The choice of method will depend on the specific study's aims and the available resources in the laboratory.

Investigating the efficacy and safety of calcipotriol/betamethasone dipropionate foam and laser microporation for psoriatic nail disease-A hybrid trial using a smartphone application, optical coherence tomography, and patient-reported outcome measures.

There is a lack of efficacious topical treatments for patients suffering from psoriatic nail disease (PND). We investigated the efficacy of Calcipotriol-Betamethasone Dipropionate (Cal/BD) foam with and without ablative fractional laser (AFL) in patients with PND. A total of 144 nails from 11 patients were treated in a 24-week long, open-label, randomized, intra-patient controlled proof-of-concept hybrid trial. In addition to daily Cal/BD foam application, half of each patient's psoriatic nails were randomized to receive optical coherence tomography (OCT)-guided AFL treatment at baseline, 6-, and 12-week follow-ups. In-clinic assessment (N-NAIL), patient-reported outcomes (PROMs), and drug consumption were supplemented by remote evaluation of 15 subclinical OCT features, smartphone app-based safety monitoring, and photo-based assessment (NAPSI). After 24 weeks of Cal/BD foam treatment, patients achieved a significant improvement (p < 0.001) in both clinical (N-NAIL -76%, NAPSI -68%) and subclinical (OCT -43%) PND severity as well as a 71% reduction in PROMs. AFL-assisted Cal/BD treatment led to higher clinical (N-NAIL -85%, NAPSI -78%) and OCT-assessed (-46%) reduction of PND signs than Cal/BD alone (N-NAIL -66%, NAPSI -58%, OCT -37%), but did not reach statistical significance. Smartphone app images documented adverse events and mild local skin reactions, particularly erythema (75%), laser-induced swelling (28%), and crusting (27%). This hybrid trial demonstrated a reduction in clinical NAPSI and N-NAIL scores, subclinical OCT features, and PROMs, suggesting that Cal/BD foam is a safe and efficacious treatment for PND. Larger trials are warranted to prove the clinical benefit of AFL pretreatment as a Cal/BD delivery enhancer.

Fractional CO2 laser ablation leads to enhanced permeation of a fluorescent dye in healthy and mycotic nails-An imaging investigation of laser-tissue effects and their impact on ungual drug delivery.

PURPOSE: Conventional oral antifungal therapies for onychomycosis (OM) often do not achieve complete cure and may be associated with adverse effects, medical interactions, and compliance issues restricting their use in a large group of patients. Topical treatment can bypass the systemic side effects but is limited by the physical barrier of the nail plate. Ablative fractional laser (AFL) treatment can be used to improve the penetration of topical drugs into the nail. This study visualized the effects of laser ablation of nail tissue and assessed their impact on the biodistribution of a fluorescent dye in healthy and fungal nail tissue. METHODS: For the qualitative assessment of CO2 AFL effects on healthy nail tissue, scanning electron microscopy (SEM), coherent anti-Stokes Raman scattering microscopy (CARS-M), and widefield fluorescence microscopy (WFM) were used. To quantitate the effect of laser-pretreatment on the delivery of a fluorescent dye, ATTO-647N, into healthy and fungal nail tissue, ablation depth, nail plate thickness, and ATTO-647N fluorescence intensity in three nail plate layers were measured using WFM. A total of 30 nail clippings (healthy n = 18, fungal n = 12) were collected. An aqueous ATTO-647N solution was directly applied to the dorsal surface of 24 nail samples (healthy n = 12, fungal n = 12) and incubated for 4 hours, of which half (healthy n = 6, fungal n = 6) had been pretreated with AFL (30 mJ/mb, 15% density, 300 Hz, pulse duration <1 ms). RESULTS: Imaging revealed a three-layered nail structure, an AFL-induced porous ablation crater, and changes in autofluorescence. While intact fungal samples showed a 106% higher ATTO-647N signal intensity than healthy controls, microporation led to a significantly increased fluorophore permeation in all samples (p < 0.0001). AFL processing of nail tissue enhanced topical delivery of ATTO-647N in all layers, (average increase: healthy +108%, fungal +33%), most pronounced in the top nail layer (healthy +122%, fungal +68%). While proportionally deeper ablation craters correlated moderately with higher fluorescence intensities in healthy nail tissue, fungal samples showed no significant relationship. CONCLUSION: Fractional CO2 laser microporation is a simple way of enhancing the passive delivery of topically applied ATTO-647N. Although the impaired nail plate barrier in OM leads to greater diffusion of the aqueous solution, AFL can increase the permeability of both structurally deficient and intact nails.

Imaging of the nail unit in psoriatic patients:A systematic scoping review of techniques and terminology.

BACKGROUND: The growing interest in the visualization of psoriatic nail unit changes has led to the discovery of an abundance of image characteristics across various modalities. OBJECTIVE: To identify techniques for non-invasive imaging of nail unit structures in psoriatic patients and review extracted image features to unify the diverse terminology. METHODS: For this systematic scoping review, we included studies available on PubMed and Embase, independently extracted image characteristics, and semantically grouped the identified features to suggest a preferred terminology for each technique. RESULTS: After screening 753 studies, 67 articles on the visualization of clinical and subclinical psoriatic changes in the nail plate, matrix, bed, folds and hyponychium were included. We identified 4 optical and 3 radiological imaging techniques for the assessment of surface (dermoscopy [n = 16], capillaroscopy [n = 12]), sub-surface (ultrasound imaging [n = 36], optical coherence tomography [n = 4], fluorescence optical imaging [n = 3]), and deep-seated psoriatic changes (magnetic resonance imaging [n = 2], positron emission tomography-computed tomography [n = 1]). By condensing 244 image feature descriptions into a glossary of 82 terms, overall redundancy was cut by 66.4% (37.5%-77.1%). More than 75% of these image features provide additional disease-relevant information that is not captured using conventional clinical assessment scales. CONCLUSIONS: This review has identified, unified, and contextualized image features and related terminology for non-invasive imaging of the nail unit in patients with psoriatic conditions. The suggested glossary could facilitate the integrative use of non-invasive imaging techniques for the detailed examination of psoriatic nail unit structures in research and clinical practice.

Low vitamin D in dark-skinned immigrants is mainly due to clothing habits and low UVR exposure: a Danish observational study.

Low 25-hydroxyvitamin D3 (25(OH)D) among dark-pigmented persons has been observed. To elucidate the reason for this we examined sun behaviour, sun-exposed body area, solar UVR exposure and 25(OH)D levels in immigrants with dark pigmented skin and Danes with light pigmented skin. Clothing, sun behaviour, and diet were recorded daily during a Danish summer season (93 analysed days). Erythema-weighted UVR doses were measured by personal electronic UVR dosimeters (with erythema response, measurement every 5th second) and 25(OH)D was measured in 72 participants (33 dark-skinned and 39 light-skinned). The immigrants exposed 28% less skin area, received 70% less UVR dose, and had 71% less 25(OH)D increase during the summer. The UVR reactivity (Δ25(OH)D per joule accumulated UVR dose) was similar (P = 0.62) among the immigrants (0.53 nmol l-1 J-1) and the Danes (0.63 nmol l-1 J-1). In the groups combined, 25(OH)D levels after summer were mainly influenced by UVR dose to exposed skin (28.8%) and 25(OH)D start level (27.9%). Height and measured constitutive skin pigmentation were of minor influence: 3.5% and 3.2%, respectively. Sun exposure and clothing habits were the main reasons for lower 25(OH)D level after summer in the darker immigrants, as both groups had similar UVR reactivity.

Few X-ray and PUVA treatments accelerate photocarcinogenesis in hairless mice.

PUVA is a treatment that combines oral methoxypsoralen (8-MOP) with ultraviolet radiation A (UVA). It is used for severe psoriasis and the early stages of T-cell lymphoma. X-rays are an effective treatment for skin cancers. Both treatments are in higher doses used to treat skin malignancies and simultaneously increase the risk of keratinocyte cancer. The main objective of this study was to test whether a few PUVA or X-ray treatments could delay the development of ultraviolet radiation (UVR)-induced skin tumors in a well-established hairless mouse model. Three groups of immunocompetent mice (total, N = 75) were included in the study. All groups were UVR-exposed during the study period. In addition, one group was treated with PUVA and another group was treated with X-rays at days 45, 52, 90 and 97. A control group was treated with UVR only. We recorded when the first, second and third skin tumors were induced in each mouse. Skin tumors developed significantly earlier in both the PUVA and X-ray groups (median, 188 days) than in the control mice (median, 215 days; p < 0.001). Therefore, a few X-ray and PUVA treatments both significantly accelerated the development of skin tumors in hairless mice, compared to UVR controls. Neither treatment showed a delay of UVR-induced skin tumors and caution should be exercised before applying these treatments to sun-damaged skin.

A Skin Cancer Prophylaxis Study in Hairless Mice Using Methylene Blue, Riboflavin, and Methyl Aminolevulinate as Photosensitizing Agents in Photodynamic Therapy.

The high incidence of sunlight-induced human skin cancers reveals a need for more effective photosensitizing agents. In this study, we compared the efficacy of prophylactic photodynamic therapy (PDT) when methylene blue (MB), riboflavin (RF), or methyl aminolevulinate (MAL) were used as photosensitizers. All mice in four groups of female C3.Cg/TifBomTac hairless immunocompetent mice (N = 100) were irradiated with three standard erythema doses of solar-simulated ultraviolet radiation (UVR) thrice weekly. Three groups received 2 × 2 prophylactic PDT treatments (days 45 + 52 and 90 + 97). The PDT treatments consisted of topical administration of 16% MAL, 20% MB, or 20% RF, and subsequent illumination that matched the photosensitizers' absorption spectra. Control mice received no PDT. We recorded when the first, second, and third skin tumors developed. The pattern of tumor development after MB-PDT or RF-PDT was similar to that observed in irradiated control mice (p > 0.05). However, the median times until the first, second, and third skin tumors developed in mice given MAL-PDT were significantly delayed, compared with control mice (256, 265, and 272 vs. 215, 222, and 230 days, respectively; p < 0.001). Only MAL-PDT was an effective prophylactic treatment against UVR-induced skin tumors in hairless mice.

How Much Protoporphyrin IX Must Be Activated to Obtain Full Efficacy of Methyl Aminolevulinate Photodynamic Therapy? Implication for Treatment Modifications.

Photodynamic therapy (PDT) with methyl aminolevulinate (MAL) is a popular treatment for actinic keratoses (AK), and several PDT treatment modalities with similar cure rates are in use. The effect relies on the activation of protoporphyrin IX (PpIX) in premalignant cells. This study aimed to measure PpIX during each treatment modality to determine the minimal PpIX activation and shortest exposure time for optimal cure rate. In four different treatment modalities, we established the PpIX formation up to three hours after MAL application without illumination and measured the speed of PpIX photoactivation during 9 min of red light (37 J/cm2). The level of PpIX three hours after MAL application was set to 100 PpIX units. In comparison, 85 PpIX units were formed during daylight PDT, 57 PpIX units during pulse PDT, and 52 PpIX units without any curettage prior to MAL. The activation of 50 PpIX units should, therefore, be enough to obtain a full effect on AK. Further, red light illumination may be shortened from 9 min to 1-2 min. The results indicate that PDT can be performed successfully with half the illumination time used in daylight PDT today and with one fourth of the illumination time used in classical PDT.

Impregnation of healthy nail tissue with optical clearing agents for improved optical coherence tomography imaging.

OBJECTIVES: The impact of optical tissue clearing on optical coherence tomography (OCT) for nail tissue imaging has not been investigated. This study seeks to compare the effects of an emollient and water on visualization of micromorphology and morphometric outcomes. MATERIALS AND METHODS: Thirty-six healthy nail plates were processed with a fractional CO2 laser, imaged with OCT, and measured with calipers in duplicates. All samples were reassessed after 12-hour long sequential immersion in water and an emollient (Crodamol™ STS). OCT images were evaluated for thickness and scattering signal of the nail. RESULTS: Emollient-impregnation caused stronger scatter responses (P < .0001) and decreased nail thickness (MD 45 µm, P < .0001) measured on OCT. Caliper-derived measurements were not affected by Crodamol™ (MD 11 µm, P = .5538). Hydration increased nail thickness on OCT (MD 49 µm, P < .0001) but reduced thickness measurements taken with calipers (MD 41 µm, P < .0001). Emollient-impregnation improved visualization of onychocytes compared with dry (P = .0209) and hydrated samples (P < .0001), and reduced occurrence of refractive artifacts (P < .0001). CONCLUSION: The use of an emollient for OCT imaging can enhance nail tissue visualization without significant effects on caliper measurements. Hydration of nails, in contrast with emollient-impregnation, may lead to disagreement between caliper- and OCT-measured nail thickness and should be practiced cautiously.

Noninvasive Assessment of Mycotic Nail Tissue Using an Ultraviolet Fluorescence Excitation Imaging System.

BACKGROUND AND OBJECTIVES: Mycological diagnosis of onychomycosis is based on direct microscopy using external fluorophores to visualize fungal tissue in nail samples and agar culture. Ultraviolet fluorescence excitation imaging (u-FEI) has shown potential in monitoring biological processes by exploiting variations in autofluorescence. This study aimed at assessing the potential of a handheld u-FEI system as a practical screening tool for fungal nail infections. STUDY DESIGN/MATERIALS AND METHODS: Ninety samples from 29 patients with microscopy-confirmed fungal infection and 10 control samples from healthy participants were collected (n = 100). Using a prototype u-FEI system (single bandpass 25 mm filter with a central pass wavelength of 340 nm and a bandwidth of 12 nm, 295 nm excitation flash, resolution of 640 × 480), images of all samples were acquired under standardized conditions. Average and maximum fluorescence intensity image values in arbitrary units (AU) of manually delineated regions of interests were quantitated and statistically assessed for significant differences between healthy and mycotic samples. RESULTS: UV-images clearly depicted all 100 nail samples, with a visibly stronger signal in infected samples. Statistically significant differences (P < 0.05) in signal intensity between mycotic samples and healthy controls were observed for maximum and average fluorescence values. Mean fluorescence values of onychomycotic samples showed 23.9% higher maximum (mycotic: 34.9 AU [standard deviation [SD] 4.7]; healthy: 28.2 AU [SD 1.9]) and 10.2% higher average (mycotic: 27.6 AU [SD 2.0]; healthy: 25.0 AU [SD 0.7]) signal intensity values. Receiver operating characteristic curves demonstrated excellent discriminatory ability (area under the curve > 0.9). Analysis of fluorescence measurements of the reference standard demonstrated very low variation (coefficient of variation = 0.62%) CONCLUSION: Quantitation of u-FEI intensities enables differentiation between healthy and mycotic nail samples, constituting a potential point-of-care tool for cost-effective screening for onychomycosis at a primary care level. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Skin surface Protoporphyrin IX fluorescence is associated with epidermal but not dermal fluorescence intensities.

BACKGROUND: Photodynamic therapy with Protoporphyrin IX (PpIX) is well-established for keratinocyte dysplasia. PpIX fluorescence can be quantified at the skin surface and within skin layers, but their relation is previously undescribed. The study objective was to assess the relation between skin surface PpIX fluorescence and PpIX fluorescence in epidermis and dermis. METHODS: Normal buttocks skin was tape-stripped and incubated with 20 % methyl aminolevulinate cream and 20 % hexyl aminolevulinate cream under occlusion. After 3 h, skin surface PpIX fluorescence photographs were captured and 4 mm punch biopsies sampled. PpIX fluorescence microscopy was measured in regions of interest (ROI) in epidermis and superficial dermis. All PpIX fluorescence intensities were calculated in arbitrary units (AU). RESULTS: Skin surface PpIX fluorescence intensity expressed a positive, linear relation to ROI-epidermis PpIX fluorescence (HAL- and MAL-incubated skin, p < 0.001, r2 = 0.60), but not to PpIX fluorescence intensities in ROI-superficial dermis (p = 0.112). PpIX fluorescence microscopy identified higher fluorescence intensities in ROI-epidermis (median 92 AU) compared to lower fluorescence intensities in ROI-superficial dermis (median 37 AU) (p < 0.001). HAL reached higher median PpIX fluorescence intensities than MAL when measured by skin surface photographs (10230 vs. 5630 AU, p < 0.001), andbyfluorescence microscopy in ROI-epidermis (107 vs. 52.5 AU, p < 0.001) or ROI-superficial dermis (40 vs. 30.5 AU, p = 0.04). CONCLUSION: The positive linear relation between skin surface PpIX fluorescence photographs and epidermal PpIX fluorescence microscopy indicates that skin surface PpIX fluorescence predominantly derives from epidermis.

Improving Photoprotection and Implications for 25(OH)D Formation.

BACKGROUND/AIM: This review examined the implications of using sunscreen photoprotection on 25(OH)D formation and determined the best photoprotective method to reduce the risk of skin cancer caused by ultraviolet radiation (UVR). Based on previous studies on 25(OH)D formation after use of different amounts of sunscreen and different doses of UVR for approximately one week to different body areas it is possible to estimate the amount of 25(OH)D formed after a week's holiday in Southern and Northern Europe. CONCLUSION: The best method of photoprotection by sunscreen is two consecutive applications before sun exposure, ensuring the use of sufficient amounts of sunscreen and minimizing the unprotected skin areas. The double application method simultaneously ensures a high photoprotection against erythema from sun exposure. Despite the use of sunscreen, the calculated serum 25(OH)D levels clearly increase to similar levels as those measured after sun vacations.

Lifetime UVR Dose and Skin Cancer Risk, Determined by Their Common Relation to Solar Lentigines.

BACKGROUND/AIM: Ultraviolet radiation (UVR) causes solar lentigines (SL) and skin cancer (SC) in humans. The association between measured lifetime UVR dose and SC has not been investigated. This study investigated this relation through their common relationship to SL. MATERIALS AND METHODS: First we investigated the association between lifetime UVR dose and SL for 16,897 days in 38 healthy participants, and secondly, the relation between SL and SC was investigated in 2,898 participants, including 149 with SC. By combining both studies, SC risk related to lifetime UVR dose and skin phototype was estimated. RESULTS: A positive association was found between SL and lifetime UVR dose (p=0.060). Skin phototype (p=0.001) and SL (p<0.001) were associated with SC. Combined SC risk increased 1.23 by doubling the average lifetime UVR dose and was 34.9 times higher for those with very fair skin compared to dark Mediterranean skin. CONCLUSION: The estimate of SC risk shows that skin phototype is of greater relative importance than lifetime UVR dose.

Inactivation of protoporphyrin IX in erythrocytes in patients with erythropoietic protoporphyria: A new treatment modality.

BACKGROUND: Erythropoietic protoporphyria (EPP) is a rare, genetic disease with reduced ferrochelatase activity causing protoporphyrine IX (PpIX) to accumulate in erythrocytes. PpIX activation by daylight causes skin erythema, edema, burning, and stinging. No treatment exists to reduce PpIX. AIM: To introduce a method that reduces PpIX in erythrocytes to relieve skin symptoms in patients with EPP. METHOD: A case series of 7 patients with EPP constituted this explorative study. Erythrocyte PpIX was inactivated by illuminating the patients' heparinized blood outside their body, then returning it to the patient. About 3 litres of blood was illuminated with 630 nm light, 20 J/cm2. The effect was measured as a reduction in erythrocyte PpIX. The patients reported the number of minutes in daylight tolerated before and after intervention. RESULTS: This procedure reduced PpIX by about 30 % and daylight tolerance was, on average, increased by 14 times. The subsequently excreted photoproducts resulted in some liver toxicity. Three treatments during spring and early summer were sufficient to reduce the patients' symptoms throughout the year in Northern Europe. CONCLUSION: Extracorporeal erythrocyte photodynamic therapy is the first treatment to successfully reduce the amount of PpIX in the blood of EPP patients, thus "normalizing" their daylight tolerance.

Advancement through epidermis using tape stripping technique and Reflectance Confocal Microscopy.

The tape stripping technique is increasingly used in research regarding skin barrier function. However, number of tape strips varies between studies, and literature considering advancement into stratum corneum/epidermis in relation to number of tape strips is scarce. The aim of this pilot study was to assess the advancement through epidermis using tape stripping technique in healthy volunteers. A total of ten healthy volunteers were included. From all volunteers 0, 5, 15 and 35 consecutive tape strips (D-squame) were taken from four adjacent skin areas on the middle volar forearm, followed by Reflectance Confocal Microscopy (RCM) of the four areas to assess epidermal thickness. Squame Scan was used to determine amount of protein removed. Stratum corneum was completely removed in all volunteers after 35 tape strips. Advancement into epidermis was predominantly achieved by the first 15 tape strips, removing 25% of the total epidermis, whereas 35 tape strips removed 33% of epidermis. Protein removal per tape decreased with increasing depth. Information on advancement into the epidermis according to number of tape strips taken, is a significant step forward. The possibility to obtain samples from different layers of epidermis may lead to an improved understanding of skin barrier properties.

A novel LC-MS/MS method to quantify eumelanin and pheomelanin and their relation to UVR sensitivity - A study on human skin biopsies.

Melanin in the skin can be divided into eumelanin and pheomelanin subtypes. Simultaneous quantification of these subtypes could clarify their relation to skin type and skin cancer development. We describe a novel, sensitive liquid chromatography-tandem mass spectrometry method to quantify two eumelanin markers, pyrrole-2,3,5-tricarboxylic acid (PTCA) and pyrrole-2,3-dicarboxylic acid (PDCA), and two pheomelanin markers, thiazole-4,5-dicarboxylic acid (TDCA) and thiazole-2,4,5 tricarboxylic acid (TTCA), performed in a single run using the same biopsy. Volunteers with either Fitzpatrick skin type (FST) I/II or III/IV (n = 30) each provided a 4-mm punch biopsy from the buttock. Upon analysis, the FST I + II group had significantly less of all four melanin biomarkers (PTCA, 0.75 ng/mm2 ; PDCA, 0.08 ng/mm2 ; TTCA, 0.24 ng/mm2 ; and TDCA, 0.10 ng/mm2 ) versus the FST III + IV group (PTCA, 4.89 ng/mm2 ; PDCA, 0.22 ng/mm2 ; TTCA, 2.61 ng/mm2 ; and TDCA, 0.72 ng/mm2 ), p ≤ 0.003. We find that this new LC-MS/MS method is sensitive enough to quantify eumelanin and pheomelanin markers even in the lightest skin types.

Serum 25(OH)D levels after oral vitamin D3 supplementation and UVB exposure correlate.

BACKGROUND: The inter-individual variation in 25(OH)D3 increase (Δ25(OH)D3 ) after vitamin D3 supplementation was determined and compared with the UVB irradiation response. METHODS: Nineteen Danish participants received 85 µg vitamin D3 (cholecalciferol) daily for nine weeks with regular serum 25(OH)D3 measurements. These participants had three years earlier taken part in a 9-week controlled UVB study. The Δ25(OH)D3 was not confounded by ambient UVB, BMI or ethnicity. RESULTS: Δ25(OH)D3 was 53 nmol L-1 and almost identical to Δ25(OH)D3 (52 nmol L-1 ) after UVB. Δ25(OH)D3 ranged from 17 to 91 nmol L-1 (span 74 nmol L-1 ) and was about half of that observed after UVB irradiation (span 136 nmol L-1 ). The interquartile ranges for vitamin D3 supplementation (38.8-71.4 nmol L-1 , span: 32.6 nmol L-1 ) and UVB irradiation (35.7-65.4 nmol L-1 , span: 29.7 nmol L-1 ) were similar indicating a comparable response of the two interventions. As the 25(OH)D3 start levels (R2  = 0.398, P = 3.8 × 10-3 ), 25(OH)D3 end levels (R2  = 0.457, P = 1.5 × 10-3 ) and Δ25(OH)D3 (R2  = 0.253, P = 0.028) between both interventions were correlated, this suggested a possible common individual background for the variation. Four pigment SNPs influenced the variation in the vitamin D3 -induced and UVB-induced Δ25(OH)D3 . A combined model including the influence of these four SNPs and the 25(OH)D3 start level explained 86.8% (P = 1.6 × 10-35 ) of the individual variation after vitamin D3 supplementation. CONCLUSION: The inter-individual variation in the two interventions was comparable and had no common demographic but a partly common genetic background.