Minimal Erythema Dose Research Articles

A Spectrophotometric Method to Determine Minimal Erythema Dose for Ultraviolet Radiation in Human Skin

Background/Objectives: Ultraviolet radiation (UVR) induces oxidative stress in the skin by generating reactive oxygen species (ROS), which can lead to inflammatory conditions including erythema (a sign of sunburn). This clinical study aims to develop an instrumental evaluation method to determine the minimal erythema dose (MED) for UVR. Methods: Fourteen human subjects aged 27 to 57 years (48.93 ± 8.54) participated in this study. Six subsites were designated on the test skin site of each subject and irradiated with UVR at different doses. The examiner visually assessed erythema, determining the ‘visual MED’. Additionally, the a* value (a chrominance parameter presenting greenness to redness) was measured using a spectrophotometer as an indicator of erythema. The a* values of the UVR-irradiated subsites were compared to the non-irradiated control value, and the differences were referred to as Δa*. The Δa* value of the subsites irradiated with UVR at the ‘visual MED’ was referred to as the Δa*VMED for each subject. The mean of the Δa*VMED values of all subjects was chosen as a criterion value for the ‘instrumental MED’. The ‘instrumental MED’ was defined as the lowest dose of UVR that causes an Δa* value equivalent to the criterion value. The ‘visual MED’ and ‘instrumental MED’ values of all subjects were subjected to correlation analysis. Results: The mean of the Δa*VMED values of all subjects was 1.88 ± 0.8. The means of the ‘visual MED’ and ‘instrumental MED’ values (in J m−2 unit) of all subjects were 300.14 ± 84.16 and 303.29 ± 77.99, respectively. In Pearson correlation analysis, the ‘instrumental MED’ and ‘visual MED’ values had a very strong positive correlation with each other (r = 0.864, p = 0.000). Conclusions: This study suggests that the instrumental evaluation method of MED based on the spectrophotometric measurement of the a* values can complement or replace the visual evaluation method and that this method will be useful in monitoring skin tolerance to oxidative stress affected by prooxidant factors and defensive factors.

Comparative Study of Cutaneous Squamous Cell Carcinogenesis in Different Hairless Murine Models

Background: In recent decades, a significant global increase in the incidence of non-melanoma skin cancer has been observed. To explore the pathogenesis of and potential therapeutic approaches for squamous cell carcinoma, various in vivo studies using mouse models have been conducted. However, investigations comparing different hairless mouse models, with or without melanin, as well as models with hypercholesterolemia and immunosuppression, in terms of their ability to induce squamous cell carcinoma have yet to be undertaken. Methods: Four mouse strains, namely SKH-hr1, SKH-hr2, SKH-hr2+ApoE, and immunodeficient Nude (Foxn1 knockout), were exposed to UVA and UVB radiation three times per week, initially to 1 Minimal Erythemal Dose (MED), incrementally increased weekly to a maximum dose of 3 MED. Clinical evaluation, photodocumentation, and biophysical parameters were monitored, along with proteasome protein activity and histopathological assessments. Results: The SKH-hr1 model primarily developed actinic keratosis without significant progression to invasive squamous cell carcinoma (SCC), while the SKH-hr2 and SKH-hr2+ApoE models exhibited a higher likelihood and intensity of papilloma and aggressive SCC formation, with the latter showing upregulated proteasome activity. Histopathological analysis confirmed the presence of poorly differentiated, invasive SCCs in the SKH-hr2 and SKH-hr2+ApoE models, contrasting with the less aggressive SCCs in the Nude mice and the mixed lesions observed in the SKH-hr1 mice. Conclusions: The SKH-hr2+ApoE and SKH-hr2 mice were identified as the most suitable for further exploration of squamous cell carcinogenesis. In contrast, the SKH-hr1 mice were found to be the least suitable, even though they are albino. Notably, proteasome analysis revealed a potential role of proteasome activity in squamous cell carcinogenesis.

2024 Results of a United Kingdom and Ireland Phototherapy Minimal Erythema Dose Survey.

2024 Results of a United Kingdom and Ireland Phototherapy Minimal Erythema Dose Survey.

Phototesting for a variety of skin conditions before narrowband (TL-01) Ultraviolet-B

Background: For the majority of photo responsive skin disorders, narrowband ultraviolet-B (NBUV-B) phototherapy is currently regarded as the preferred option. The initial dosage of NBUV-B phototherapy is determined as a percentage of the minimal erythema dose (MED) at the majority of dermatology centers that offer phototherapy. This will shorten the time of therapy and lower the chance of burning while optimizing the therapeutic effect. Three times a week is the usual dosage for NBUV-B phototherapy treatment, which takes 18 to 30 sessions on average to clear the condition. For these types of treatment plans, a precise evaluation of the MED is necessary before starting treatment in order to prevent NBUV-B overdoses or underdoses. Aim: The objective of this study is to investigate the MED of 311nm NBUV-B phototherapy in a group of Libyan patients. Methods: For this prospective study, 150 patients with a range of skin conditions who saw the phototherapy unit at Bir Usta Melad Hospital of Dermatology and Venereology in Tripoli, Libya over an 8-month period were enrolled. Skin conditions include vitiligo, atopic dermatitis, and psoriasis are among those being researched. Using Fitzpatrick's questionnaire, skin types were assigned to each patient. Using a MED tester instrument (Dermalight® 80), 311 nm NBUV-B was applied to the right forearm. The test findings were recorded 24 hours later. Results: Of the patients studied, 82 (54.7%) were female and 68 (45.3%) were male. Their ages ranged from 10 to 60 years, with 30% of the sample falling between the ages of 31 and 40. The patients were clinically diagnosed with the following conditions: vitiligo 65(43.3%), psoriasis 61(40.7%), eczema 8(5.3%), pruritus 6(4%), and alopecia areata and lichen planus 5(3.3%) each. According to Fitzpatrick's categorization, the skin prototypes in the included series were 15(10%) patients of skin type III, 118(78.7%) patients of skin type IV, and 17(11.3%) patients of skin type V. Among the enrolled participants, the minimum necessary dose to elicit an erythema for NBUV-B ranged between 300 mJ/cm2 and 750 mJ/cm2, with the mean dosage was 484.7 ± 82.2 mJ/cm2. Conclusions: The average MED to 311nm NBUV-B in Libyan patients was around 500 mJ/cm2, which can be utilized to determine the initial dose and treatment regimen of phototherapy for various skin conditions.

Oral administration of cysteine peptides attenuates UV-B-induced skin erythema and pigmentation in humans

The oral administration of antioxidants may suppress UV-B-induced skin damage. HITHION YH-15, the extract of Torula yeast (Cyberlindnera jadinii), is rich in cysteine-containing peptides such as reduced and oxidized glutathione (GSH and GSSG), γ-glutamylcysteine (γ-Glu-Cys), and cysteinylglycine (Cys-Gly). These four constituents are termed cysteine peptides. In this study, we investigated the protective effects of cysteine peptides against UV-B in a randomized, placebo-controlled, double-blind, parallel-group study. A total of 90 healthy males and females aged 30–59 years were enrolled and randomized into two groups of 45 individuals each (cysteine peptides (48 mg/day) and placebo). Changes in UV-B-induced erythema and pigmentation were compared between groups after 5 weeks of test food intake. The minimal erythema dose (MED) significantly increased (*p = 0.019) in the cysteine peptides group compared to that in the placebo group, indicating suppression of UV-B-induced erythema. ΔL* value significantly increased (***p < 0.0001) in the cysteine peptides group compared to that in the placebo, indicating pigmentation suppression. We demonstrated that oral administration of cysteine peptides suppresses UV-B-induced erythema and pigmentation through multiple mechanisms. Thus, cysteine peptides may find use as nutricosmetics for maintaining skin health and well-being.UMIN Clinical Trials Registry ID: UMIN 000050157.

Mitigation of ultraviolet-induced erythema and inflammation by para-hydroxycinnamic acid in human skin.

To evaluate whether p-hydroxycinnamic acid (pHCA) alone and in combination with niacinamide (Nam) can mitigate UV-induced erythema, barrier disruption, and inflammation. Three independent placebo-controlled double-blinded studies were conducted on female panellists who were pretreated on sites on their backs for 2 weeks with skin care formulations which contained 0.3% or 1% pHCA with 5% Nam, 1% pHCA alone, 1.8% octinoxate, or control formula. Treated sites were then exposed to 1.5 minimal erythemal dose (MED) solar simulated radiation (SSR) and had chromameter and expert grading measures for erythema, barrier integrity via TEWL, and the skin surface IL-1RA/IL-1α inflammatory biomarkers isolated from D-Squame tapes. Across the three independent studies, pHCA alone or in combination with Nam showed a significant mitigation of UV-induced erythema, barrier disruption, and levels of the surface inflammatory biomarkers IL-1RA/IL-1α. The cinnamate analogue Octinoxate did not replicate the effects of pHCA. The study results show that pHCA alone or in combination with Nam can mitigate UV-induced damage to skin. These include mitigation of UV-induced erythema as measured by instrument and expert grade visualization. Additionally, pHCA with Nam protected damage to the barrier and reduced the induction of the SASP-related surface inflammatory biomarker IL-1RA/IL-1α. The inability of Octinoxate to have any protective effect and the detection of low levels of pHCA on skin surface after 24 h of application supports that these effects are based on a biological response to pHCA. These findings add to the body of evidence that pHCA alone or in combination with Nam can enhance the skin's biological response to UV-induced damage. This supports pHCA can potentially impact aging and senescence, thereby maintain skin's functionality and appearance.

Continuum of light sensitivity in atopic dermatitis: A retrospective analysis of 139 cases in Scotland

BackgroundPrevious reports have characterized photosensitivity in atopic dermatitis (AD), but with differences in terminology and criteria. ObjectiveThis study aims to assess outcomes in 139 AD patients referred for photodiagnostic testing and to establish diagnostic criteria for photosensitivity in AD. MethodsClinical and photodiagnostic data were reviewed, categorizing photosensitivity into Photo-Exacerbated AD (PEAD), Photo-Sensitive AD (PSAD), and Chronic Actinic Dermatitis (CAD). ResultsOf the patient cohort, mean age was 42.6±16.7 years and 61.9% were male. PEAD patients (51.1%) had normal monochromator phototesting. PSAD patients (7.9%) displayed slight-to-moderate UVA sensitivity (≥30% of normal minimal erythema dose [MED]) and mostly normal/slightly reduced UVB MEDs (≥80% of normal MED). Conversely, 41% of patients had CAD and 93% of this group demonstrated significant UVB sensitivity, with very low UVB MEDs (<80% of normal MED) and/or very low UVA MEDs (<30% of normal MED). No significant differences in sex, age, or skin phototype were observed between groups. Serial phototesting revealed changes in photosensitivity status over time in eight patients. LimitationsSmall sample size and retrospective design. ConclusionsThis study highlights the heterogeneity of photosensitivity patterns in AD patients and the importance of follow-up assessments due to potential shifts in disease spectrum over time.

Topical nanoencapsulated cannabidiol cream as an innovative strategy combating UV-A–induced nuclear and mitochondrial DNA injury: A pilot randomized clinical study

BackgroundUltraviolet-A radiation (UVA) contributes to photoaging/photocarcinogenesis by generating inflammation and oxidative damage. Current photoprotective strategies are limited by availability/utilization of UVA filters, highlighting an unmet need. Cannabidiol (CBD), having anti-inflammatory/antioxidant properties via regulation of NFR-2, HMOX1, and PPAR-y, could potentially mitigate damage from UVA exposure. Objective/MethodsProspective, single-center, pilot clinical trial (NCT05279495). Nineteen participants applied nano-CBD (nCBD) or vehicle (VC) cream to randomized, blinded buttock sites twice-daily for 14-days, then treated sites were irradiated with ≤3x UVA minimal erythema dose. After 24-hours, punch biopsies were obtained for histology, immunohistochemistry, real-time PCR. ResultsAt 24-hours, 21% of participants had less observed erythema on CBD-treated skin than VC skin. Histologically, nCBD-treated skin had reduced UVA-induced epidermal hyperplasia than VC (p=0.01). Immunohistochemistry detected reduced cytoplasmic/nuclear 8-oxo-guanine glycosylase 1 staining in nCBD-treated skin compared to VC (p<0.01). Quantitative mtDNA PCR demonstrated UVA-induced deletion of ND4 (proxy:4977bp deletion; p=0.003) and ND1 (proxy:3895bp deletion; p=0.002) were significantly reduced by in vivo nCBD treatment compared to VC. LimitationsSample size. ConclusionTopically applied nCBD cream reduced UVA-induced formation of a frequent mutagenic nuclear DNA base lesion and protected against mtDNA mutations associated with UVA-induced skin aging. This trial is the first to identify UV-protective capacity of CBD-containing topicals in humans.

Formulation and Activity of Sunscreen Cream from Ethanol Extract of Calendula officinalis L Flowers

Sunscreen made of natural ingredients is an alternative to protect the skin from excess UV radiation and a substitute for chemical products that have side effects. It was reported that Calendula officinalis L. has flavonoid and saponin metabolite compounds which function as photoprotective agents. This research aims to formulate sunscreen cream and examine the effect of variations in Calendula officinalis L flower extract (5%;7%;10% w/v) on physicochemical properties, stability, and values of the Sun Protecting Factor (SPF) in vitro using UV-Vis spectrophotometry and in vivo using wistar line rat test animals to see the time of formation of Minimum Erythema Dose (MED). It has been proven that variations in the concentration of Calendula officinalis L. extract affected the physicochemical properties, such as pH value, viscosity, spreadability, and adhesion strength. However, the overall results of the physicochemical properties still met the requirements. Variations in extract concentration affected the SPF value. In vitro SPF test showed the minimum protection category for F1, extra protection for F2, maximum protection for F3, and no protection for F0. Meanwhile, the in vivo SPF test showed the minimal protection category for F1, medium protection for F2, extra protection for F3, and no protection for F0.

A Bayesian network meta-analysis of 14 molecules inhibiting UV daylight-induced pigmentation.

Hyperpigmentation disorders are very frequent, affect the quality of life and may become a psychological burden for afflicted patients. Many anti-pigmenting or depigmenting agents are available with various efficacy and almost no comparative data. 2-mercaptonicotinoyl glycine (2-MNG) was recently proposed as a viable candidate showing safe and effective results on hyperpigmentation control invitro and invivo. A Bayesian network meta-analysis (BNMA) was conducted to map and rank the anti-pigmenting and depigmenting efficacy of 2-MNG 0.5% on UV daylight (UVDL)-induced pigmentation together with 13 other reference molecules. A comparison in the kinetics of 2-MNG 0.5% was also performed. Fourteen studies were conducted, for each, on 15-30 women of skin phototype III in Shanghai, China and Paris, France. The products were applied on mini zone, in randomized and blinded protocol, on the back, 5 days a week during 6 weeks, at a dose of 4 mg/cm2. During the second week, volunteers were exposed under to varying minimum erythemal dose of UVDL during 4 consecutive days-adapted to obtain a similar induction of skin pigmentation regardless of the population. Assessments were performed instrumentally using Chromameter®. Ascorbic acid 7% was used as a positive control for all experiments. A Bayesian network meta-analysis was then established to map and follow the kinetics of 2-MNG 0.5% performance with 13 reference molecules (glutathione 2%, kojic acid 1%, hydroquinone 4%, ascorbyl glucoside 2%, niacinamide 4%, etc.). 2-MNG 0.5% dominated the ranking at all time points with a significant high probability of strong efficacy against UVDL-induced pigmentation. Ascorbic acid 7% ranks second after 4 days of irradiations (D12) whereas hydroquinone 4% ranks second 1 month after irradiations (D40). In the kinetics, 2-MNG at 0.5% was effective as from the end of irradiations (D12) to the study endpoint (D40). This suggested an immediate and persistent efficacy across all timepoints evaluated. The BNMA revealed a rapid and lasting efficacy of 2-MNG 0.5% on the anti-pigmenting and depigmenting phases of the clinical protocol. 2-MNG 0.5% ranked first, with immediate and lasting effect compared to 13 other references. This study is the first allowing comparison between reference anti-pigmenting and depigmenting agents and will help clinicians for proposing the most effective approach for their patients.

Eradication of skin microbiota restores cytokine production and release in polymorphic light eruption.

Polymorphic light eruption (PLE) has been mechanistically linked to cytokine abnormalities. Emerging preclinical evidence posits the skin microbiome as a critical modulator of ultraviolet (UV)-induced cytokine expression, thereby influencing subsequent immune responses. This intricate relationship remains underexplored in the context of PLE. Hence, we investigated the differential responses between disinfected and non-disinfected skin following both single and repetitive exposures to solar-simulated UV radiation in patients with PLE. An experimental, half-body pilot study was conducted involving six PLE patients and 15 healthy controls. Participants' skin was exposed to single and multiple doses of solar-simulated UV radiation, both in disinfected and in non-disinfected skin areas. The co-primary outcomes were PLE score and cytokine expression in blister fluid analysed through OLINK proteomic profiling. Secondary outcomes were erythema, pigmentation, induction of apoptotic cells in vacuum-generated suction blisters, and density of infiltrate in skin biopsies of PLE patients. Among the 71 cytokines analysed, baseline expression levels of 20 specific cytokines-integral to processes such as apoptosis, inflammation, immune cell recruitment, cellular growth, and differentiation-were significantly impaired in PLE patients compared with healthy controls. Notably, skin disinfection reversed the observed cytokine imbalances following a single UV exposure at the minimal erythema dose (MED) level and exhibited even more pronounced effects after multiple UV exposures. However, no significant differences were evident in PLE score, erythema, pigmentation, or rates of apoptotic cell induction upon UV radiation. These findings provide evidence for UV-driven cytokine regulation by the skin microbiota and imply microbiome involvement in the PLE immune response.

Redefine photoprotection: Sun protection beyond sunburn.

Excessive exposure to ultraviolet (UV) light leads to acute and chronic UV damage and is the main risk factor for the development of skin cancer. In most countries with western lifestyle, the topical application of sunscreens on UV-exposed skin areas is by far the most frequently used preventive measure against sunburn. Further than preventing sunburns, increasing numbers of consumers are appreciating sunscreens with a medium- to high-level sun protective factor (SPF) as basis for sustainable-skin ageing or skin cancer prevention programs. However, recent investigations indicate that clinically significant DNA damages as well as a lasting impairment of cutaneous immunosurveillance already occur far below the standard of one minimal erythema dose (MED) sunburn level, which contributes to the current discussion of the clinical value of high-protective SPF values. Exvivo investigations on human skin showed that the application of SPF30 reduces DNA damage for a day long sun exposure (24 MED) drastically by about 53% but is significantly surpassed by SPF100 reducing DNA damage by approx. 73%. Further analysis on different SPF protection levels in UV-exposed cell culture assays focusing on IL-18, cell vitality and cis/trans-urocanic acid support these findings. Whereas SPF30 and SPF50+ sunscreens already offer a solid UVB cover for most indications, our results indicate that SPF100 provides significant additional protection against mutagenic (non-apoptotic-) DNA damage and functional impairment of the cutaneous immunosurveillance and therefore qualifies as an optimized sunscreen for specifically vulnerable patient groups such as immunosuppressed patients, or skin cancer patients.

New-insight UVB Treatment for Psoriasis Vulgaris in Vietnamese Patients.

Narrowband UVB (NBUVB) has recently been used in Vietnam for the treatment of psoriasis. However, there are no data on Vietnamese patients to adopt a uniform national protocol. This study aimed to establish an optimal NBUVB therapy for the treatment of psoriasis in Vietnamese patients. One hundred and twenty-two patients with psoriasis vulgaris were included. They were randomly allocated to two groups: the percentage dose (group 1, 62 patients) and the fixed dose (group 2, 60 patients). In group 1, the starting dose was 50% of the minimal erythema dose (MED) and the 10% increment dose adjusted in the next sessions. In group 2, the starting dose was based on Fitzpatrick skin types (fixed dose). Psoriasis area and severity index (PASI) was used to evaluate efficacy. More than 68% of the patients get PASI75 at session 36. Group 2 had significantly fewer sessions (20 ± 5 vs 25 ± 7, P- value = 0.0004) and lower cumulative dose than group 1 (14.1 ± 4.3 J/cm2 vs 18.0 ± 8.0 J/cm2, P- value = 0.0075) to achieve PASI75. Adverse effects were more common in group 2 than group 1, including burning sensation/erythema (43.33% vs 14.52%, P- value = 0.0009) and pruritus (75.00% vs 22.58%, P- value <0.0001). NBUVB therapy was safe and effective for Vietnamese psoriasis patients. Fixed doses produced a quicker clinical response with fewer sessions and lower cumulative doses. Adverse effects were mild in both groups and less noted for the MED-based dose. For the recommendation, a fixed dose should be applied for patients who have less concern about side effects, while a MED-based dose can be suitable for patients having conditions related to light sensitivity.

Plant-Derived Extracts Plus Vitamin E and/or Aloe Vera Protect Against Intrinsic/Extrinsic Stressor in Human Skin: In Vitro and Clinical Evidence.

Humans are exposed to physical, biological, chemical, and psychological stressor throughout their life span. In recent years many medicinal plants have been shown to induce stress adapting and protective functions. Plant-derived extracts and vitamin E exhibit stress protection or resistance by normalizing cellular homeostasis and enhancing resistance to toxic stimuli to overcome cellular damage. Here we report the evaluation of a topical preparation (product test materials; PTM) containing an ingredient blend of Rhodiola Rosea, Eleutherococcus Senticosus (Siberian Ginseng), Rhaponticum Carthamoides, Inonotus Obliqus, and Slegainella Lepidophylla as the base formula and tested the addition of Lespedeza Capitata (leaf/stem) extract plus vitamin E and/or Aloe Vera to determine the induced protective functions in human skin when challenged with intrinsic and extrinsic stressors. The base topical preparation plus Lespedeza Capitata extract plus vitamin E or the base topical preparation plus vitamin E and Aloe Vera were assayed in vitro on (a) intrinsically stressed excised abdominoplasty skin, (b) full thickness (FT) skin equivalent models post-treated with a combination of ultra-violet (UV) B light (250 mJ/cm2) and diesel particular matter (DPM) (75 µg/mL) skin, for their effect on antioxidant, inflammation, and stress biomarker geners. Additionally, the bioadaptive activity of the PTMs was confirmed in providing resilience and protection against UV-induced erythema. For example, in a clinical study, daily topical application of the PTMs on the buttocks of 20 woman (18-78 years old), average age of 51.1 years, median body mass index (BMI) of 26.5 for 8 weeks followed by 2 minimal erythema dose (MED) of UVB exposure was accessed 24 hours after irradiation. Statistical analysis was performed by t-test and ANOVA, repectively. Pretreatment with the topical PTMs on intrsinically stressed skin significantly reduced the expression of the stress gene biomarkers, p53, pro-inflammatory cytokines Interleukin-1β (IL-1β) and Tumor Necrosis Factor-α (TNFα) and the pro-apoptotic BCL2 associated X, apoptosis regulator (BAX) values compared to controls. Topical application of the PTMs on Full Thickness (FT) human skin treated with UVB light and DPM significantly enhanced the stress response by activating heat shock transcription factor 4 (HSF4) and heat shock protein family B (small) member 1 (HSPB1) gene levels belonging to the heat shock protein (HSP) family by significantly increasing the expression of heme oxygenase 1 (HMOX1). At the same time, significantly reducing IL-1β levels were observed plus protection of skin cells from toxicity ocurred by significantly increasing the expression of B-cell lymphoma 2 (BCL2) (anti-apoptotic gene). In the clinical study, daily topical applications of the PTMs for 8 weeks followed by 2MED of UVB irradiation with clinical assessment 24 hours later revealed a significantly reduced intensity of erythema when compared to the buttock region treated with UVB alone. The PTMs containing adaptogen ingredients may confer stress resistance and induce stress protective responses against intrinsic as well as extrinsic stressors as demonstrated by the obtained in vitro and clinical evidence.

The Predicting the Value of Local Individual Minimal Erythema Dose without Test Ultraviolet Irradiation

The article substantiates the need for a prognostic approach and formulates the problem to assessing minimal erythema dose (MED) in dermatology without UV test exposure. Arguments are given in favor of using a number of optical non-invasive diagnostic methods for this purpose. The photosensitivity of human skin to ultraviolet radiation is determined by its optical and morphological parameters, as well as the reactivity of the skin microvasculature. These values can be determined before treatment; therefore, it is theoretically possible to predict an individual MED for healthy and psoriasis-affected skin. The article substantiates possible methods and approaches for solving this problem, proposes an optical model of the skin, and describes the proposed research protocol.

Evaluating the factors influencing sun protection factors (SPF): Pooling data from multiple studies involving two reference ISO 24444:2019 sunscreen products (P2 and P8).

Standardized methods for sun protection factor (SPF) testing are still beset with endpoint and method-driven issues, and can be influenced by multiple factors. The purpose of this analysis is to explore the factors influencing the results of sun protection factor (SPF) testing in human subjects according to the ISO 24444:2019 standard. Intrinsic factors, such as baseline skin color, age and gender, the minimal erythemal dose on an unprotected area (MEDu), as well as environmental factors such as season/weather influences, are considered for analysis. Datasets generated for two reference products (P2 and P8) during the conduct of 50 such studies using the ISO standard 24444:2019 for the testing of SPF products, from a single testing center located in Bucharest, Romania between April 2021 and December 2022, were retrieved and compiled. Overall, the data for 334 subjects was available, with 276 observations for the reference P8, and 171 for P2. No effects due to gender or age were detected. Seasonal changes, the individual typology angle (ITA°) and MEDu were found to have an influence on the outcome of the SPF values. This study adds new original data about the impact of intrinsic and extrinsic factors on SPF variations pertaining to ISO reference sunscreen P8 (SPF 50+). The findings suggest that some factors will inevitably impact the results between two SPF experiments for the same product and SPF testing laboratory. The interconnections between the sources of this variation are discussed. The findings of this research help to identify and characterize factors that contribute to SPF testing variability.

The Impact of Antioxidants on Vitiligo and Melasma: A Scoping Review and Meta-Analysis.

Reactive oxygen species (ROS) generated during melanogenesis make melanocytes particularly vulnerable to oxidative stress, influencing their survival and melanin synthesis. Oxidative stress, significantly present in vitiligo and recently also detected in melasma, triggers inflammatory cascades and melanogenesis, making antioxidants a promising therapeutic avenue. A systematic search was conducted on Embase and Pubmed to study the efficacy of antioxidants for treating vitiligo and/or melasma. Meta-analysis was performed to assess the difference in Melasma Severity Index (MASI) scores between baseline and follow-up. Various antioxidants like polypodium leucotomos, ginkgo biloba, catalase/superoxide dismutase, and vitamin E have potential in vitiligo. For melasma, vitamin C, silymarin, and niacinamide were among those showing promise in reducing pigmentation, with vitamin C displaying significant effects in meta-analysis. Different antioxidants improve both vitiligo and melasma, with an increased minimal erythema dose (MED) following UV exposure being significant for vitiligo and tyrosinase inhibition being crucial for melasma. However, the efficacy of individual antioxidants varies, and their exact mechanisms, especially in stimulating melanocyte proliferation and anti-inflammatory pathways, require further investigation to understand better and optimize their use.

Theoretical Substantiation of the Possibility of Performing Non-Damaging UV Diagnostics of Biological Tissues In Vivo

Since UV radiation is capable of causing skin erythema, there is a risk of damage during in vivo UV spectroscopy of skin. In particular, the conventional estimation of radiation dose indicates the impossibility of conducting such studies when using fiber sources to deliver UVA and UVB radiation to the skin due to the rapid accumulation of the minimal erythema dose (MED). Using numerical simulations, we investigated the possibility of achieving MED when exposing the skin to UV light of diagnostic power and forming irradiation spots of different sizes. It has been shown that the conventional approach to calculating the dose as radiant exposure (J/cm2) turns out to be unsuitable in the case of irradiation spots of small area (which is the case when fiber sources are used) since it greatly overestimates the dose. This, in turn, results in a significant underestimation of the permissible duration of the diagnostic procedure. The reason for this is the failure to take into account the diffusion of radiation in biological tissue. We substantiated that for a more correct calculation of the dose taking into account diffusion, it is necessary to estimate the volumetric energy density (J/cm3) in biological tissue. In vivo experiments confirmed that this approach is more correct in determining the time to reach erythema compared to the conventional approach. The calculations showed that the minimum spot area of UVA/UVB irradiation on the skin surface, beyond which the calculation of the dose as radiant exposure does not introduce a significant error, is 1.5–3 mm2, which corresponds to diameters of 1.4–2 mm in the case of a round irradiation spot.

Efficacy of Oral Lycopene Supplementation for Photoprotection in Filipino Patients in a Tertiary Hospital in Makati: A Single-blind Randomized Controlled Trial

Abstract Background: Ultraviolet radiation has been proven to result in unwarranted effects on the skin through reactive oxygen species (ROS) and direct DNA damage. Lycopene, a naturally occurring substance, acts as an antioxidant by neutralizing ROS. Objective: The objective of the study was to determine the efficacy of oral lycopene supplementation for photoprotection in adult Filipino patients seen in a tertiary hospital in Makati City. Design: The study design involves single-blind, parallel, randomized controlled trial. Methods: Thirty-six Filipino patients aged 18 years old and above with Fitzpatrick Skin Phototype (FSP) III–V were divided into two groups using a computer-generated randomization. Group A received lycopene 500 mg/soft gel capsule two capsules per orem once daily for 12 weeks, while Group B received no intervention during the entire observation period. Minimal erythema dose (MED) of patients from both groups was assessed by a single treatment-blinded reader at baseline, week 6, and week 12. Results: Group A showed a significant increase in MED across periods, with a 20.83% increase from baseline at week 6 and a 43.06% increase at week 12. Group B MED remained constant from baseline to week 6 and to week 12. These results show that there is a significant effect in the increase in MED as compared to the control group. Conclusion: Oral lycopene is effective in increasing the MED of patients and may be used for photoprotection among patients with FSP III–V.

Exploring adult-onset actinic prurigo in Thailand.

Actinic prurigo (AP) is an uncommon photodermatosis. In European and Native American populations, AP is more common in young women and demonstrates clinical improvement or remission in adulthood. The clinical signs of AP differ in Asians because the disorder typically occurs in adults (adult-onset AP) and is clinically persistent. The objective of this study was to investigate the characteristics and outcomes of patients with AP in Thailand. A total of 15 cases with AP were evaluated. All of them were adult-onset AP (mean onset age of 45.5 years). Males predominated (66.7%). The majority of them manifested with papules on the face and upper extremities. Mucositis was present in 2 patients. Phototesting revealed that the minimal erythematous dose (MED) for UVA decreased in 3 subjects and the MED for both UVA and UVB decreased in other 3 patients. A photo-provocation test was performed on 9 patients with normal MED, and 5 of them showed positive UVA photo-provocation, while 4 showed positive UVA and UVB photop-rovocation. A systemic immunosuppressant was prescribed in 60% of patients. Median time for clinical improvement was 8.6 months. Complete clinical remission was found in only 3 patients. Adult-onset AP has different clinical features and responds differently to treatment, compared to classical AP.