EEMCO guidance for the in vivo assessment of skin surface pH

Genistein transfersome-embedded topical delivery system for skin melanoma treatment: in vitro and ex vivo evaluations

Skin melanoma is considered the most dangerous form of skin cancer due to its association with high risk of metastasis, high mortality rate and high resistance to different treatment options. Genistein is a natural isoflavonoid with known chemotherapeutic activity. Unfortunately, it has low bioavailability due to its poor aqueous solubility and excessive metabolism. In the current study, genistein was incorporated into transferosomal hydrogel to improve its bioavailability. The prepared transferosomal formulations were characterized regarding: particle size; polydispersity index; zeta potential; encapsulation efficiency; TEM; FTIR; DSC; XRD; in vitro drug release; viscosity; pH; ex vivo anti-tumor activity on 3D skin melanoma spheroids and 1-year stability study at different storage temperatures. The optimized formulation has high encapsulation efficiency with an excellent particle size that will facilitate its penetration through the skin. The transfersomes have a spherical shape with sustained drug release profile. The anti-tumor activity evaluation of genistein transfersome revealed that genistein is a potent chemotherapeutic agent with enhanced penetration ability through the melanoma spheroids when incorporated into transfersomes. Stability study results demonstrate the high physical and chemical stability of our formulations. All these outcomes provide evidence that our genistein transferosomal hydrogel is a promising treatment option for skin melanoma.

The Skin Acid Mantle: An Update on Skin pH

The acid mantle concept refers to the buffer system located in the upper stratum corneum of the skin. By sustaining an acidic environment, the acid mantle contributes to the regulation of the microbiome, structural stability, and inflammation. Skin pH is pivotal in maintaining the integrity of the epidermal barrier. Shifts in pH can disrupt barrier properties, and recent studies have emphasized its impact on dermatologic disease processes. This review explores the complex relationship of mechanisms through which skin pH impacts dermatologic pathologies. Furthermore, we highlight the promising potential of pH-targeted therapies for advancing the management of skin conditions.

Effects of a pH-Regulating Emollient Cream in Mild Atopic Dermatitis Patients with Moderate Localized Lesions

INTRODUCTION

Increased skin pH values in patients with atopic dermatitis (AD) contribute to poor antimicrobial and permeability barrier functions of the skin. In practice, the majority of topical preparations available for dry skin conditions do not provide sufficient pH and buffering capacity for maintaining optimum skin surface conditions. To address this issue, we tested a novel zinc lactobionate preparation to determine whether the regular application would lower skin surface pH, and in doing so improve the condition of lesional skin.

METHODS

The assessment for local severity of AD was done with the Scoring Atopic Dermatitis Index (SCORAD) and skin dryness was assessed by capacitance measurement.

RESULTS

The results showed that the test product lowered skin pH and improved AD skin lesions from moderate to mild during 2 weeks of application. In the treated area a lowered pH of about 0.85 units was found. Together with the lowering of pH, the local SCORAD significantly improved from 8.3 on average down to 4.0, while in the untreated area, only a slight improvement (from 8.2 to 6.4) was found.

CONCLUSION

Synergistic effects of the test product's pH lowering and emollient properties might explain the observed improvements in clinical signs of AD and further research against a comparator would allow the specific contribution of pH modulation to these improvements to be unambiguously isolated.

Clinical efficacy of a multilamellar cream on skin physiology and microbiome in an epidermal stress model: A controlled double-blinded study

INTRODUCTION

Stratum corneum (SC) is essential for skin barrier function, mitigating water loss and shielding against potentially harmful substances and allergens. The SC's lipid matrix, arranged in a lamellar structure, is integral to its protective role. Our study explores the restoration effects of a multilamellar cream with an acidic pH compared to a basic placebo cream on skin physiology and its interaction with the skin microbiome after stress induction via tape stripping (TS).

MATERIALS AND METHODS

In this double-blind study, 14 healthy participants aged 21-58 years were assessed pre- and post-tape stripping, followed by a 14 days application of a multilamellar test cream and a placebo cream with evaluations on days 7, 14 and 17 for sustained effects. Skin physiology was analysed in terms of epidermal barrier function, SC hydration and surface pH. The microbiome was analysed by 16S rRNA amplicon sequencing the 16S rRNA gene using Illumina MiSeq, with subsequent species identification.

RESULTS

Our study showed significant improvements in skin barrier repair and SC hydration with verum, particularly after 14 days of application, while both creams initially enhanced stratum corneum hydration. No significant changes in surface-pH were detected. The skin microbiome analysis revealed that TS slightly decreased alpha diversity, a trend that verum significantly reversed, enhancing diversity beyond baseline levels after 14 days. Overall, while both creams contributed to a broader microbial phyla diversity over time, no significant changes in the abundance of specific genera or species were noted between treatments.

DISCUSSION AND CONCLUSION

Our study delineates the efficacy of a pH-optimized multilamellar cream in enhancing epidermal barrier recovery and SC hydration post-sequential TS, in contrast to an unstructured basic placebo. Verum cream significantly improved skin barrier function and SC hydration at day 14, with sustained effects evident beyond the treatment period. Furthermore, the multilamellar formulation facilitated the restitution of cutaneous microbiome diversity, a key indicator of healthy skin ecology, underscoring the symbiotic relationship between barrier integrity and microbial composition. These findings underscore the importance of multilamellar emollient structures in dermatological therapeutics, with potential implications for the design of advanced skincare interventions that holistically support cutaneous resilience and homeostasis.

Effects of a mattress cover with special airflow technology on the structure and function of the sacral and heel skin during loading: A two-arm exploratory crossover trial

Prolonged mechanical loading of the skin and underlying soft tissue cause pressure ulceration. The use of special support surfaces are key interventions in pressure ulcer prevention. They modify the degree and duration of soft tissue deformation and have an impact on the skin microclimate. The objective of this randomized cross-over trial was to compare skin responses and comfort after lying for 2.5 h supine on a support surface with and without a coverlet that was intended to assist with heat and moisture removal at the patient/surface interface. In addition, physiological saline solution was administered to simulate an incontinence episode on the mattress next to the participants' skin surface. In total, 12 volunteers (mean age 69 years) with diabetes mellitus participated. After loading, skin surface temperature, stratum corneum hydration and skin surface pH increased, whereas erythema and structural stiffness decreased at the sacral area. At the heel skin area, temperature, erythema, and stratum corneum hydration increased. These results indicate occlusion and soft tissue deformation which was aggravated by the saline solution. The differences in skin response showed only minor differences between the support surface with or without the coverlet.

Screen-printed wearable skin surface pH sensor for real-time monitoring of the buffering capacity of human skin

This study demonstrated for the first time that skin surface pH can be monitored in real-time, using a screen-printed wearable pH sensor, to evaluate the buffering capacity of the human skin. The screen-printed pH sensor was composed of a polyaniline-based pH-sensitive electrode and a nitrocellulose membrane-based liquid junction type of Ag/AgCl reference electrode. This sensor showed a reliable and reversible potentiometric response to pH with long-term potential stability. Intermittent monitoring of the buffering capacity of skin surface pH demonstrated the reliability of the proposed wearable pH sensor, which was comparable to that of a commercially available flat-tip pH sensor. We found that contact of the wearable pH sensor with the subject's skin via aqueous electrolyte solutions was necessary for the sensor to continuously monitor the skin surface pH while sustaining the natural buffer capacity of the human skin surface.

Effects of a leave-on product on the strength of the dermoepidermal junction: An exploratory, intraindividual, randomized controlled trial in older adults with dry skin

Background and Aims

Skin aging is associated with dry skin and a decrease of the strength of the dermoepidermal adhesion, which increases the risk for lacerations (skin tears). Application of leave-on products improves dry skin and seems to reduce skin tear incidence. The aim of this study was to measure the effects of a humectant containing leave-on product on the strength of the dermoepidermal junction in older adult participants with dry skin.

Methods

A randomized controlled trial using a split body design was conducted. One forearm was randomly selected and treated with a lipophilic leave-on product containing 5% urea for 8 weeks. The other forearm was the control. The parameters stratum corneum hydration (SCH), transepidermal water loss, pH, roughness, epidermal thickness and skin stiffness were measured at the baseline, Weeks 4 and 8. At Week 8, suction blisters were created and time to blistering was measured. Blister roofs and interstitial fluid were analyzed for Interleukin-1α, 6 and 8.

Results

Twelve participants were included. After 8 weeks treatment, SCH was higher (median difference 11.6 AU), and the overall dry skin score (median difference -1) and median roughness (Rz difference -12.2 µm) were lower compared to the control arms. The median group difference for Interleukin-1α was -452 fg/µg total protein (TP) in the blister roofs and -2.2 fg/µg TP in the blister fluids. The median time to blister formation was 7.7 min higher compared to the control arms.

Conclusion

The regular application of humectant containing leave-on products improves dry skin and seems to lower inflammation and contribute to the strengthening of the dermoepidermal adhesion. This partly explains how the use of topical leave-on products helps to prevent skin tears.

An update of skin permeability data based on a systematic review of recent research

The cutaneous absorption parameters of xenobiotics are crucial for the development of drugs and cosmetics, as well as for assessing environmental and occupational chemical risks. Despite the great variability in the design of experimental conditions due to uncertain international guidelines, datasets like HuskinDB have been created to report skin absorption endpoints. This review updates available skin permeability data by rigorously compiling research published between 2012 and 2021. Inclusion and exclusion criteria have been selected to build the most harmonized and reusable dataset possible. The Generative Topographic Mapping method was applied to the present dataset and compared to HuskinDB to monitor the progress in skin permeability research and locate chemotypes of particular concern. The open-source dataset (SkinPiX) includes steady-state flux, maximum flux, lag time and permeability coefficient results for the substances tested, as well as relevant information on experimental parameters that can impact the data. It can be used to extract subsets of data for comparisons and to build predictive models.

Maintenance of an Acidic Skin Surface with a Novel Zinc Lactobionate Emollient Preparation Improves Skin Barrier Function in Patients with Atopic Dermatitis

INTRODUCTION

The skin of patients with atopic dermatitis (AD) is characterised by elevated pH. As a central homeostatic regulator, an increased pH accelerates desquamation and suppresses lipid processing, resulting in diminished skin barrier function. The aim of this study was to determine whether a novel zinc lactobionate emollient cream can strengthen the skin barrier by lowering skin surface pH.

METHODS

A double-blind, forearm-controlled cohort study was undertaken in patients with AD. Participants applied the test cream to one forearm and a vehicle cream to the other (randomised allocation) twice daily for 56 days. Skin surface pH and barrier function (primary outcomes) were assessed at baseline and after 28 days and 56 days of treatment, amongst other tests.

RESULTS

A total of 23 adults with AD completed the study. During and after treatment, a sustained difference in skin surface pH was observed between areas treated with the test cream and vehicle (4.50 ± 0.38 versus 5.25 ± 0.54, respectively, p < 0.0001). This was associated with significantly reduced transepidermal water loss (TEWL) on the test cream treated areas compared with control (9.71 ± 2.47 versus 11.20 ± 3.62 g/m2/h, p = 0.0005). Improvements in skin barrier integrity, skin sensitivity to sodium lauryl sulphate, skin hydration, and chymotrypsin-like protease activity were all observed at sites treated with the test cream compared with the control.

CONCLUSION

Maintenance of an acidic skin surface pH and delivery of physiologic lipids are beneficial for skin health and may help improve AD control by reducing sensitivity to irritants and allergens.

Enhancing skin health and safety in aged care (SKINCARE trial): A cluster-randomised pragmatic trial

BACKGROUND

Older nursing home residents are prone to develop different skin conditions at the same time, including xerosis cutis, skin tears, pressure ulcers, incontinence-associated dermatitis or intertrigo. Guidelines and recommendations mainly address these skin conditions separately. The overall aim of this study was to measure the effects of the implementation of a skincare and prevention package.

TRIAL DESIGN

A two-arm cluster-randomised controlled trial was conducted.

METHODS

In nursing homes being assigned to the intervention group, an evidence-based and structured skincare and prevention programme was implemented for six months. Nursing home residents in the control group received standard care as usual. Blinded dermatologists conducted head-to-toe skin assessments, and the researchers assessed skin barrier parameters including stratum corneum hydration and transepidermal water loss at the upper and lower extremities after three and six months. Outcomes included the cumulative incidence of incontinence-associated dermatitis, skin tears, pressure ulcers and intertrigo, and were presented as intention-to-treat and per protocol analysis. Skin dryness and resident-reported outcomes (pain, itch, quality of life) were assessed.

RESULTS

A random sample of 17 nursing homes in the federal state of Berlin, Germany, was drawn and randomised in intervention (n = 9) and control groups (n = 8). In total, 165 participants were allocated to the intervention, and 149 participants were allocated to the control group. The cumulative incidence of skin tears (19.2 %, 95 % CI 12.8-27.8), pressure ulcers (13.6 %, 95 % CI 8.1-21.9) and intertrigo (27.0 %, 95 % CI 18.4-37.7) was lower in the intervention compared to the control group, with cumulative incidences of 27.2 % (95 % CI 19.3-36.9) for skin tears, 16.9 % (95 % CI 10.6-25.9) for pressure ulcer, and 37.8 % (95 % CI 27.5-49.4) for intertrigo. The incidence of incontinence-associated dermatitis was higher in the intervention group (26.3 %, 95 % CI 17.9-36.8) compared to the control group (23.1 %; 95 % CI 14.6-34.5). Mean skin dryness was lower in the intervention group but showed variation. The impact on pain, itch, and quality of life was trivial.

CONCLUSIONS

The present study results indicate that the implementation of tailored and evidence-based nursing routines improves skin health and safety in residential long-term care. Evidence suggests that multiple adverse skin conditions can be prevented by regular skin assessments and individually tailored skincare routines. Positive effects on skin dryness were observed, but skin physiology parameters did not indicate changes of the skin barrier function.

TRIAL REGISTRATION

This study is registered at the German Clinical Trials Register (registration number: DRKS00015680; date of registration: January 29th, 2019) and ClinicalTrials.gov (NCT03824886; date of registration: January 31st, 2019).

The prevalence and severity of dry skin and related skin care in older adult residents in institutional long-term care: A cross-sectional study

OBJECTIVES

To identify possible factors associated with different severities of xerosis cutis and to describe possible associations between (skin) care dependency and application of moisturizers.

DESIGN

Cross-sectional study using baseline data from a cluster-randomized controlled trial. Demographic and health characteristics, skin physiological measurements, functional abilities and application of moisturizers were compared between the participants with mild and severe dry skin. Frequency of moisturization were also compared based on the participants' skin care dependency.

RESULTS

The more distal the body area, the more severe xerosis were observed. There were no or minor differences between the groups, except for the stratum corneum hydration and skin surface pH. Participants with severe xerosis received moisturizers less often. Skin care dependent residents received moisturizers frequently.

CONCLUSION

There is under-application regarding xerosis cutis treatment in long-term care. Skin care provided by nurses, in adequate frequencies, might be helpful compared to skin care performed by the residents themselves.

Selective detection of urease-producing bacteria on the genital skin surface in patients with incontinence-associated dermatitis

We aimed to investigate the association between the presence of cutaneous urease-producing bacteria and the development of incontinence-associated dermatitis (IAD) using an original urea agar medium as a step toward developing advanced preventive measures. In previous clinical assessments, we developed an original urea agar medium to detect urease-producing bacteria via the medium's colour changes. In a cross-sectional study, specimens were collected via the swabbing technique at genital skin sites in 52 stroke patients hospitalised in a university hospital. The primary objective was to compare the presence of urease-producing bacteria between the IAD and no-IAD groups. Determining the bacterial count was the secondary objective. The prevalence of IAD was 48%. A significantly higher detection rate of urease-producing bacteria was observed in the IAD group than in the no-IAD group (P = .002) despite the total number of bacteria being equivalent between them. In conclusion, we discovered that there was a significant association between the presence of urease-producing bacteria and IAD development in hospitalised stroke patients.

Association Between Skin Acid Mantle, Natural Moisturizing Factors, and Antibacterial Activity Against S. aureus in the Stratum Corneum

Purpose

The skin has evolved a system to prevent pathogenic microorganism colonization and infection. This study examined the role of natural moisturizing factors (NMFs) and skin pH on Staphylococcus aureus (S. aureus) growth and colonization on the human stratum corneum (SC).

Study Population and Methods

A survey study with 82 female participants was performed. Participants maintained their daily hygiene routine, except for refraining from using leave-on products on their forearms on the day of the test. Skin sampling was performed using adhesive tapes. An ex vivo method was developed to study the viability and growth of S. aureus on human SC sampled from normal skin. NMFs, including pyrrolidone carboxylic acid (PCA), urocanic acid (UCA), histidine, and proline in SC samples, were measured by liquid chromatography with tandem mass spectrometry. The impact of PCA and UCA on S. aureus growth and metabolic activity was measured by optical density and isothermal microcalorimetry, respectively.

Results

Heterogeneity of S. aureus viability on human SC samples was observed. Skin pH showed a significant negative association (p<0.05) with SC antibacterial activity in the ex vivo assay. One unit of skin pH decrease corresponded to 68.1% of S. aureus cell death. The levels of PCA and histidine were significantly negatively associated (p<0.05) with skin pH. The addition of 5 mM and 10 mM PCA significantly inhibited S. aureus growth by approximately 25% at 20 hours and reduced its metabolic activity in vitro.

Conclusion

The results indicate that PCA, one of the NMFs in human skin, plays an important role in regulating the human skin acid mantle in vivo and contributes to antibacterial activity against S. aureus.

Effects of impermeable and semipermeable glove materials on resolution of inflammation and epidermal barrier impairment after experimental skin irritation

BACKGROUND

Semipermeable membranes might be suitable for glove liners or comfort gloves in individuals with irritant contact dermatitis (ICD).

OBJECTIVES

To evaluate the effects of different glove materials on inflammation and epidermal barrier impairment after experimental skin irritation.

METHODS

Nine test areas on the volar forearms of 24 healthy volunteers were irritated with sodium lauryl sulfate (1%) and afterward covered for 6 days (6 or 8 h/day) with semipermeable Sympatex (SYM), vinyl (OCC), combinations of vinyl with Sympatex (SYM/OCC) or cotton (COT/OCC), or left uncovered (CON). Up to day 10, measurements of transepidermal water loss (TEWL), erythema (a*), skin humidity (SH) and visual scoring (VS) were applied.

RESULTS

No significant differences in skin parameters were found between COT/OCC and SYM/OCC as well as between each of the combinations and CON. SYM, COT/OCC and SYM/OCC led to better results for most skin parameters than OCC alone.

CONCLUSIONS

Occlusive material has a negative impact on skin barrier recovery and inflammation after skin irritation whereas SYM is not inferior to uncovered areas indicating good tolerability. Altogether, the data suggest that SYM is a useful alternative to COT as material for glove liners and comfort gloves in ICD patients.

Skin Physiology, Mucosal Functions, and Symptoms Are Modulated by Grass Pollen and Ozone Double Exposure in Allergic Patients

INTRODUCTION

Along with climate changes, we see an increase in allergic symptoms and the number of pollen-allergic patients in many countries. Increased allergic symptoms are associated with an elevated ozone exposure which may be linked by impaired epithelial barrier function. This study aimed to quantify the clinical effect of ozone and pollen double exposure (DE). We tested whether ozone impairs barrier-related skin physiology and mucosal functions under DE with pollen in grass pollen-allergic patients versus healthy controls.

METHODS

This case-control study included 8 grass pollen-allergic patients and 8 non-allergic healthy subjects exposed to grass pollen and ozone in the GA2LEN pollen chamber, comparing shorter and longer DE duration. Non-invasive skin physiological parameters were assessed, including stratum corneum hydration, skin redness, surface pH, and basal transepidermal water loss as a parameter for epidermal barrier function. The subjects' general well-being, bronchial, nasal, and ocular symptoms were documented.

RESULTS

Skin physiology tests revealed that DE in allergic patients deteriorates the epidermal barrier function and increases the surface pH and skin redness. DE significantly induced nasal secretion in pollen-allergic versus healthy subjects, which was more pronounced with longer DE. The general well-being was significantly impaired under DE versus pollen or ozone alone, with a negative influence of DE duration. No relevant bronchial symptoms were recorded.

CONCLUSION

Skin physiology and nasal mucosal symptoms are negatively affected by ozone and grass pollen DE in allergic patients. The negative effects showed, in some parameters, a dose (time)-response relationship. The pH can be regarded as a possible modulatory mechanism.

Insights into Health Risks of Face Paint Application to Opera Performers: The Release of Heavy Metals and Stage-Light-Induced Production of Reactive Oxygen Species

Face paints used by opera performers have been shown to contain high levels of heavy metals. However, whether frequent exposure, via dermal contact and inadvertent oral ingestion, results in occupational diseases is unknown, as is the potential exacerbation of toxicity by high-intensity irradiation from stage lights. In this study, we examined the release of Cr, Cu, Pb, and Zn from 40 face paints and the consequent health risks posed by different practical scenarios involving their use. The results showed that the in vitro bioaccessibility (IVBA) of Cr, Cu, Pb, and Zn in the tested products was, on average, 7.0, 5.5, 19.9, and 7.9% through oral ingestion and 1.1, 2.2, 1.6, and 1.2% through dermal contact, respectively. Stage light irradiation significantly increased the IVBA associated with dermal contact, to the average of 4.8, 34.9, 5.7, and 1.9% for Cr, Cu, Pb, and Zn, respectively. The increase was mainly due to the light-induced generation of reactive oxygen species, particularly hydroxyl free radicals. The vitality and transcriptional response of 3D skin models as well as a quantitative risk assessment of skin sensitization indicated that dermal contact with face paints may induce predictable skin damage and potentially other skin diseases. Long-term exposure to face paints on stage may also pose a non-carcinogenic health risk. The demonstrated health risks to opera performers of face paint exposure should lead to strict regulations regarding the content of theatrical face paints.

Towards a modern approach to traditional use of Helichrysum italicum in dermatological conditions: In vivo testing supercritical extract on artificially irritated skin

ETHNOPHARMACOLOGICAL RELEVANCE

Helichrysum italicum has been widely used in traditional medicine to treat allergies, colds, cough, skin, liver and gallbladder disorders, inflammation, infections, and sleeplessness. Furthermore, it possesses considerable wound healing and skin protective properties, documented by several in vivo studies performed on animals. However, there is a lack of experimental evidence supporting its potential as a topical agent tested by human clinical trials.

AIM OF THE STUDY

The study aimed to investigate the skin protective activity of cotton gauze and polypropylene non-woven fabric, impregnated with H. italicum extract by the integrated supercritical CO₂ extraction-supercritical solvent impregnation process.

MATERIALS AND METHODS

The integrated process of supercritical CO₂ extraction of H. italicum and the impregnation of cotton gauze and polypropylene non-woven fabric was performed under 350 bar and 40 °C with and without the addition of ethanol as a cosolvent. Impregnated textile materials were tested in vivo for their bioactivity on irritated human skin. Randomized in vivo studies performed involved assays of both safety and efficacy of the impregnated textiles. The effects were evaluated using the in vivo non-invasive biophysical measurements of the following skin parameters: electrical capacitance, transepidermal water loss, melanin index, erythema index, and skin pH.

RESULTS

Both cotton gauze and polypropylene non-woven fabric were impregnated with H. italicum extracts under supercritical conditions with considerable values of the impregnation yield (1.97%-4.25%). The addition of ethanol as a cosolvent during the process caused significant changes in the incorporated extracts' impregnation yield and chemical profile. Both impregnated textile materials were safe, evaluated by their testing on the human skin with no cause of any irritation and redness. However, efficacy studies revealed that polypropylene non-woven fabric impregnated with H. italicum extract with ethanol as a cosolvent, possessed significantly greater potential for skin protection than the other investigated samples.

CONCLUSIONS

The present study demonstrated the feasibility of the combined supercritical extraction and impregnation process in developing materials for topical application based on H. italicum extract. The results of in vivo studies performed on human volunteers confirmed the suitability of H. italicum active components to be a part of human skin protective preparations because of their ability to maintain the skin unimpaired. Traditionally claimed applications as a medicinal plant capable of regenerating skin have been scientifically proven, in addition to employing green technology in obtaining the impregnated materials with a broad spectrum of utilization.

Characterization and ex vivo evaluation of excised skin samples as substitutes for human dermal barrier in pharmaceutical and dermatological studies

BACKGROUND

Excised animal and human skins are frequently used in permeability testing in pharmaceutical research. Several factors exist that may have influence on the results. In the current study some of the skin parameters that may affect drug permeability were analysed for human, mouse, rat and pig skin.

MATERIALS AND METHODS

Classic biophysical skin parameters were measured (e.g. pH, hydration, permittivity, transepidermal water loss). Physiological characteristics of the skins were also analysed by confocal Raman spectroscopy, scanning electron microscopy and two-photon microscopy.

RESULTS

Based on biophysical testing, skin barrier function was damaged in psoriatic mouse skin and in marketed pig skin. Hydration and pH values were similar among the species, but freezing and thawing reduced the water content of the skins and shifted the surface pH to acidic. Aging reduced hydration and permittivity, resulting in impaired barrier function. Mechanical sensitization used in permeability studies resulted in proportional thinning of dead epidermis.

DISCUSSION

Results indicate that depending on the scientific question it should be considered whether fresh or frozen tissue is used, and for certain purposes rodent skins are well usable. The structure of the skin tissue (ceramide, cholesterol, keratin, natural moisturizing factor or urea) is similar in rats and mice, but due to the higher skin thickness the lipid distribution is different in porcine skin. Psoriasis led to irregular chemical composition of the skin.

CONCLUSION

A comprehensive evaluation of skin samples of four species was performed. The biophysical and microscopic observations should be considered when selecting drug penetration models and experimental conditions.

Skin Barrier Function in Infants: Update and Outlook

A good understanding of infant skin should provide a rationale for optimum management of the health of this integument. In this review, we discuss the skin barrier function of infants, particularly with reference to the use of diapers and baby wipes. The skin barrier of newborns continues to develop with age. Two years after birth, the barrier properties of infant skin closely resemble those of adult skin. However, several risk factors may contribute to impaired skin barrier and altered skin permeability in infants. Problems may arise from the use of diapers and baby wipes. The skin covered by a diaper is effectively an occluded environment, and thus is vulnerable to over-hydration. To date there has been no published information regarding dermal absorption of ingredients contained in baby wipes. Similarly, dermal absorption of topical ingredients in infants with underlying skin conditions has not been widely explored. Clearly, there are serious ethical concerns related to conducting skin permeation studies on infant skin. However, the increasing availability of non-invasive methods for in vivo studies is encouraging and offers new directions for studying this important patient group.

An exploratory study of the effects of the pH of synthetic urine on skin integrity in healthy participants

Background: Incontinence-associated dermatitis (IAD) develops from prolonged exposure of skin to urine and/or stool and represents a common complication in older adults, reducing the quality of life. Increased pH is an important etiologic factor of IAD, however, the relationship between urinary pH and skin barrier disruption remains unclear. Objective: To examine the effects of synthetic urine (s-urine) at various pH on transepidermal water loss (TEWL), stratum corneum hydration (SCH) and skin surface pH. Methods: S-urine solutions (pH 5.0-9.0) were applied to the volar forearms of 15 healthy participants for 2 hrs, with another site serving as the untreated control. Measurements of TEWL, SCH and skin surface pH were obtained at baseline and after each challenge. Skin buffering capacity was also examined in 5 volunteers by recording skin pH at baseline, after 2 hrs exposure and every 5 mins for 40 mins. Results: TEWL and SCH were increased following exposure to s-urine compared to baseline values. Although there was tendency for pH to an increase after exposure, further investigation showed that changes are only temporal as pH value is restored to baseline within 5 mins. There were no significant differences between solutions. Conclusions: This study revealed that urine disrupts healthy skin integrity; however, its effects are not pH dependent. Transient changes were observed on the acid mantle of the skin due to its innate buffering capacity. Future studies need to examine the effects of urine combined with bacteria responsible for pH elevation in patients with urinary incontinence.

Impact of pH on growth of Staphylococcus epidermidis and Staphylococcus aureus in vitro

The pH of skin is critical for skin health and resilience and plays a key role in controlling the skin microbiome. It has been well reported that under dysbiotic conditions such as atopic dermatitis (AD), eczema, etc. there are significant aberrations of skin pH, along with a higher level of Staphylococcus aureus compared to the commensal Staphylococcus epidermidis on skin. To understand the effect of pH on the relative growth of S. epidermidis and S. aureus, we carried out simple in vitro growth kinetic studies of the individual microbes under varying pH conditions. We demonstrated that the growth kinetics of S. epidermidis is relatively insensitive to pH within the range of 5-7, while S. aureus shows a stronger pH dependence in that range. Gompertz's model was used to fit the pH dependence of the growth kinetics of the two bacteria and showed that the equilibrium bacterial count of S. aureus was the more sensitive parameter. The switch in growth rate happens at a pH of 6.5-7. Our studies are in line with the general hypothesis that keeping the skin pH within an acidic range is advantageous in terms of keeping the skin microbiome in balance and maintaining healthy skin.

Role of pH in skin cleansing

BACKGROUND

The importance of maintaining the acid-mantle of human stratum corneum to maintain its healthy barrier and skin's biological functions such as desquamation and lipid biosynthesis is well recognized in the literature. An outcome of this has been an increase in the number of skincare products formulated at or near the skin pH with an implication that a product formulated at skin pH will be good for skin. Such an assumption often does not take into account the specific interactions of ingredients in the product with the stratum corneum under skin pH conditions.

OBJECTIVE

The objective of this research was to determine whether a skin cleansing product by virtue of its pH being same as "skin pH" is milder to skin.

METHODS

A well established Forearm Controlled Application Test (FCAT) protocol was used in clinical studies to compare "skin pH" cleansing systems with neutral pH cleansing systems. Specifically, certain commercially available "skin pH" cleansing bars were compared with a neutral pH syndet bar in two separate FCAT studies. Since these bars differed in their surfactant composition, in a separate FCAT study, two identical prototype bar formulations differed only in their pH were compared. Additionally, two body wash liquid prototypes, identical in composition but differing only in their pH were also compared in another FCAT study.

RESULTS

The results obtained showed that skin-cleansing systems formulated solely or predominantly with anionic surfactants under skin pH conditions can result in increased skin dryness and irritation compared to those under neutral pH conditions. The results are explained in terms of the increased electrostatic interaction of anionic surfactants with stratum corneum under low pH conditions compared to neutral pH conditions.

CONCLUSION

Skin-cleansing systems formulated solely or predominantly with anionic surfactants under skin pH conditions can result in increased skin dryness and irritation compared to those under neutral pH conditions. Any skin cleansing product by virtue of its pH being same as that of "skin pH" does not guarantee that it will be good for skin. The mildness of a cleanser will be determined by the interactions of its surfactants and other ingredients with stratum corneum under its formulated pH conditions.

Temporal Variation of the Facial Skin Microbiome: A 2-Year Longitudinal Study in Healthy Adults

BACKGROUND

The human skin microbiome is highly personalized, depending on, for example, body site, age, gender, and lifestyle factors. The temporal stability of an individual's skin microbiome-its resiliency and robustness over months and years-is also a personalized feature of the microbiome. The authors measured the temporal stability of the facial skin microbiome in a large cohort of subjects. In addition to measuring microbiome dynamics, they tracked facial skin condition using noninvasive, objective imaging and biophysical measures to identify significant facial features associated with temporal changes in microbiome diversity and composition.

METHODS

The authors used 16S ribosomal RNA amplicon sequencing to track cheek and forehead skin microbiome diversity and composition annually over a 2-year period (2017-2019) in 115 healthy adult men and women. Skin metadata included facial features, such as wrinkles, hyperpigmentation, porphyrins, and skin color tone, as well as biophysical parameters for stratum corneum barrier function, pH, hydration, and elasticity.

RESULTS

Across the subject population, the facial skin microbiome composition and diversity were relatively stable, showing minor variation over the 2-year period. However, for some subjects, composition, diversity, and relative abundance of specific organisms showed substantial changes from one year to the next, and these changes were associated with changes in stratum corneum barrier function and follicular porphyrins.

CONCLUSIONS

For healthy people, facial skin microbiome diversity and composition are relatively stable from year to year. Tracking the temporal changes in the microbiome along with skin phenotypic changes allows for a deeper understanding of the skin microbiome's role in health and disease. These results should be helpful in the design of longer-term intervention trials with microbiome-based skin care treatments.

Formulation and Evaluation of Alcohol-Free Hand Sanitizer Gels to Prevent the Spread of Infections during Pandemics

Hand hygiene is an essential factor to prevent or minimize the spread of infections. The ability to prepare an alcohol-free hand sanitizer (AFHS) with antimicrobial properties is crucial, especially during pandemics, when there are high demands and a low supply chain for ethanol and isopropanol. The objective of this study was to prepare AFHS gels based on natural materials that contain essential oils (EOs) that would be effective against a broad spectrum of pathogens. The results showed that the organoleptic characteristics of all prepared hand sanitizer gels were considered acceptable. The pH of the formulations was slightly acidic (circa 3.9) owing to the presence of aloe vera in large proportions (90% v/v), which is known for its acidity. The spreadability for all tested formulations was in the acceptable range. The antimicrobial effectiveness test demonstrated that the prepared hand sanitizer gels had antimicrobial activities against different gram-positive and gram-negative bacteria and Candida albicans yeast. The highest antibacterial effect was observed with tea tree oil hand sanitizers, which lack activity against the yeast, while clove oil hand sanitizers showed effectiveness against all microorganisms, including Candida albicans. The lavender hand sanitizer exhibited the least antimicrobial efficiency. The acceptability study on 20 human volunteers showed that the hand sanitizer gel containing 1.25% (v/v) clove oil did not produce any signs of skin irritation. This study suggested that the prepared natural hand sanitizer gel with 1.25% (v/v) clove oil can be a potential alternative to commonly used alcohol-based hand sanitizers (ABHS).

Formulation of topical acidic products and acidification of the skin - Contribution of glycolic acid

OBJECTIVE

The acidic skin pH is one of the regulating factors of skin barrier homeostasis. Topical products as extrinsic factors which influence skin pH could be used for acidification of the skin and consequent beneficial effect. To formulate stabile and safe topical emulsion product with low pH is on-going challenge and areas interesting to explore are related to the effect of acidic products on the skin pH together with development of protocols for these studies. Aim of our work was to investigate formulations of acidic topical products with glycolic acid (GA) stabilized with long chain alkyl polyglucoside emulsifier, in regard to the specific colloidal structure of the vehicle, together with effect of products with different concentration of acidic active on skin pH.

METHODS

Investigated formulations were basic vehicle and two creams with glycolic acid (concentration 2 and 10 wt%). Microstructure was investigated by polarization microscopy, Raman spectral imaging, thermal analysis and rheological measurements. Effects on the skin were assessed by measurement of biophysical skin parameters in vivo studies (5-hour, 24-hour and 7-days). In vitro screening of antimicrobial activity was performed against bacteria Staphylococcus epidermidis.

RESULTS

Polarization micrographs and Raman images have shown that GA does not disturb the specific colloidal structure. Together with rheological and thermal analysis obtained results have shown that GA in higher concentrations contributes to vehicles' lamellar structure. In 5-hour study the mean values of skin pH ranged from 3.98-4.25 and 3.89-4.10 after application of products with smaller and higher GA concentration. GA samples lowered skin surface pH to 5 and less in 24-hour and 7-day study, with stronger effect of sample with more GA. Sample with 10% of GA had significant inhibitory effect on growth of S. epidermidis in 1:1 concentration.

CONCLUSIONS

Investigated APG emulsifier could be used as a stabilizer for acidic topical products with GA which are characterized by satisfactory safety profile. Topical products induce acidification of the skin after short- and long-term application without barrier impairment or sign of irritation. Acidification of the skin depends on presence of ingredients which are proton donors and their concentrations.

Changes in Skin Barrier Function after Repeated Exposition to Phospholipid-Based Surfactants and Sodium Dodecyl Sulfate In Vivo and Corneocyte Surface Analysis by Atomic Force Microscopy

(1) Background: The aim of the study was to evaluate the effect of pure lecithins in comparison to a conventional surfactant on skin in vivo. (2) Methods: Physiological skin parameters were evaluated at the beginning and the end of the study (day 1 and day 4) (n = 8, healthy forearm skin) with an Aquaflux^®, skin-pH-Meter, Corneometer^® and an Epsilon^® sensor. Confocal Raman spectroscopy was employed to monitor natural moisturizing factor, urea and water content of the participants' skin. Tape strips of treated skin sites were taken and the collected corneocytes were subjected to atomic force microscopy. Circular nano objects were counted, and dermal texture indices were determined. (3) Results: Transepidermal water loss was increased, and skin hydration was decreased after treatment with SDS and LPC80. Natural moisturizing factor and urea concentrations within the outermost 10 µm of the stratum corneum were lower than after treatment with S75 or water. Dermal texture indices of skin treated with SDS were higher than skin treated with water (control). (4) Conclusions: Results suggest very good (S75) or good (LPC80) skin-tolerability of lecithin-based surfactants in comparison to SDS and encourage further investigation.

Premature infant skin barrier maturation: status at full-term corrected age

OBJECTIVE

To evaluate the effects of gestational age (GA) and postnatal age on skin barrier integrity by comparing premature infants at full-term corrected age with infants born at term.

STUDY DESIGN

Parallel comparison of chest skin in 36 premature infants with 39 full-term infants using daily measures of transepidermal water loss (TEWL), skin pH, erythema and rash, over 2 weeks.

RESULT

Chest skin pH was significantly lower for premature infants, indicating that acid mantle formation had occurred in the premature versus full-term infants. Chest TEWL was significantly higher for premature versus full-term infants over 2 weeks, suggesting that even 7-8 weeks after birth, skin integrity is poorer in premature infants.

CONCLUSION

Skin barrier properties of premature infants at adjusted full-term age differ from full-term infants, suggesting that epidermal barrier development depends on GA and time from birth. These maturational differences may influence premature infant response to topical agents.

Effect of hydroxypropyl-β-cyclodextrin in fluid and semi-solid submicron emulsions on physiological skin parameters during regular in vivo application

Objective

The aim of the present study was to evaluate the effect of hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) in cosmetic submicron emulsions and submicron emulsion gels on physiological skin parameters during regular application in a clinical set‐up.

Methods

Formulation morphology was investigated using cryo‐transmission electron microscopy. Stability of the employed formulations was determined by photon correlation spectroscopy, measurement of pH and rheological properties. Effect on physiological skin parameters was evaluated during regular application over four weeks in a parallel group study (n = 15, healthy forearm skin) with a Corneometer, Sebumeter, skin‐pH‐Meter, Aquaflux and an Epsilon sensor. Confocal Raman spectroscopy was employed to monitor urea and NMF levels.

Results

Both submicron emulsions and gels showed satisfying storage stability irrespective of cyclodextrin incorporation. No statistically significant effects on skin barrier function and any of the observed parameters were obtained, indicating good skin tolerability of all tested formulations.

Conclusion

Results suggest good skin tolerability of the developed cosmetic submicron emulsions and gels with HP‐β‐CD.

The influence of topical 5% tranexamic acid at pH 2.38 with and without corundum microdermabrasion on pigmentation and skin surface lipids

Tranexamic acid (TA) has anti-hemorrhagic effects; however, oral administration has been found to decrease hyperpigmentation. The aim of the work was to compare the effects of treatment with 5% tranexamic acid in combination with corundum microdermabrasion on skin pigmentation, redness, pH, transepidermal water loss (TEWL), sebum level and hydration of back surface and dorsal surface of the hand skin. Six treatments were performed every week on the back surface and both dorsal surfaces of the hands of 12 subjects. The entire back/both hands were treated with 5% tranexamic acid at pH 2.38; left side of the back or left hand were also subjected to corundum microdermabrasion. Skin parameters were measured using the Courage & Khazaka 580 Multi Probe Adapter. Clinical photos were taken using the Fotomedicus system. Significant differences between treatment methods were observed for melanin, erythema and pH. In addition, the two methods differed significantly with regard to the amount of sebum, TEWL and the level of moisture in the skin. Both methods gave similar acidic pH. Summing up tranexamic acid causes a significant reduction in epidermal melanogenesis, has a significant impact on the level of skin hydration, lipids of the epidermis and maintaining the proper TEWL. TA has a significant effect on reducing skin redness.

Favorable effect of creams with skimmed donkey milk encapsulated in nanoliposomes on skin physiology

The use of donkey milk has a long history in external dermal application for cosmetic and medical purposes. The encapsulation of different drugs into nanoliposomes and nutrients may have many benefits for the delivery of the targeted substance. The aim of the present study is to test creams with nanoliposomes encapsulated with skimmed donkey milk, reported in our registered patent, compared with effect of the placebo cream and the untreated skin. To investigate the effect of formulated cream, we have measured the electrical capacitance, transepidermal water loss and the skin pH value. The study included 15 healthy volunteers (11 women and 4 men). The patented creams exhibited satisfactory moisturizing properties very soon after application, while hydration was reached earlier in the spots treated with night cream. Transepidermal water loss slightly decreased only after 4 weeks of treatment in each of the spots assessed. The pH value was similar after each of the treatments. Tested creams may enhance the moisture of skin very soon after application, in this way potentially enable deeper permeation of phospholipids and essential proteins, without changing the pH. It may also contribute to additional anti-aging effects.

Short-term skin reactions following use of N95 respirators and medical masks

Background

In the context of the COVID‐19 pandemic, cases of adverse skin reactions related to the wearing of masks have been observed.

Objectives

To analyze the short‐term effects of N95 respirators and medical masks, respectively, on skin physiological properties and to report adverse skin reactions caused by the protective equipment.

Methods

This study used a randomized crossover design with repeated measurements. Twenty healthy Chinese volunteers were recruited. Skin parameters were measured on areas covered by the respective masks and on uncovered skin 2 and 4 hours after donning, and 0.5 and 1 hour after removing the masks, including skin hydration, transepidermal water loss (TEWL), erythema, pH, and sebum secretion. Adverse reactions were clinically assessed, and perceived discomfort and non‐compliance measured.

Results

Skin hydration, TEWL, and pH increased significantly with wearing the protective equipment. Erythema values increased from baseline. Sebum secretion increased both on the covered and uncovered skin with equipment‐wearing. There was no significant difference in physiological values between the two types of equipment. More adverse reactions were reported following a N95 mask use than the use of a medical mask, with a higher score of discomfort and non‐compliance.

Conclusions

This study demonstrates that skin biophysical characters change as a result of wearing a mask or respirator. N95 respirators were associated with more skin reactions than medical masks.

Skin barrier function after repeated short-term application of alcohol-based hand rub following intervention with water immersion or occlusion

BACKGROUND

Alcohol-based hand rub (ABHR) is recommended for hand hygiene, and application on dry skin is generally well tolerated. However, hydration of the skin may lead to increased susceptibility to ABHR.

OBJECTIVES

To evaluate if increased skin hydration changes skin barrier response to ABHR, as compared to application on dry skin.

METHODS

Twenty healthy volunteers participated in a 3-day experimental setup. Intervention areas on the forearms were exposed to either water immersion or occlusion followed by repeated exposures to ABHR. Skin barrier function was assessed by measurement of transepidermal water loss (TEWL), electrical conductance, pH, and erythema at baseline and day 3.

RESULTS

The area exposed to water immersion preceding ABHR showed a significant increase in TEWL from baseline to day 3 (P = .04), and for the occluded area the same trend was found (P = .11), with an additional decrease in electrical conductance (P = .03). No significant differences were found for the control area. The assessments did not differ significantly between intervention and control sites.

CONCLUSION

Our results indicate that extensive skin hydration may lead to increased susceptibility to ABHR. Further evaluation of this observation is important, since ABHRs are widely used, particularly among health care workers in whom hand eczema is a huge problem.

Assessment of non-invasive techniques and herbal-based products on dermatological physiology and intercellular lipid properties

Skin is the largest external organ of the human body. It acts as a barrier to protect the human body from environmental pollution, mechanical stress, and excessive water loss. The defensive function resides primarily on top of the epidermis layer commonly known as stratum corneum (SC). Human SC consists of three major lipids, namely ceramide, free fatty acid, and cholesterol that comprise approximately 50%, 25%, and 25% of the total lipid mass, respectively. The optimal composition of SC lipids is the vital epidermal barrier function of the skin. On the other hand, skin barrier serves to limit passive water loss from the body, reduces chemical absorption from the environment, and prevents microbial infection. In contrast, epidermal lipids are important to maintain the cell structure, growth and differentiation, cohesion and desquamation as well as formation of a permeability barrier. Multiple non-invasive in vivo approaches were implemented on a regular basis to monitor skin physiological and intercellular lipid properties. The measurement of different parameters such as transepidermal water loss (TEWL), hydration level, skin elasticity, collagen intensity, melanin content, sebum, pH, and tape stripping is essential to evaluate the epidermal barrier function. Novel non-invasive techniques such as tape stripping, ultrasound imaging, and laser confocal microscopy offer higher possibility of accurate and detailed characterisation of skin barrier. To date, these techniques have also been widely used to determine the effects of herbal plants in dermatology. Herbal plants have been traditionally used for ages to treat a variety of skin diseases, as reported by the World Health Organisation (WHO). Their availability, lower cost, and minimal or no side effects have created awareness among society, thus increase the demand for natural sources as the remedy to treat various skin diseases. This paper reviews several non-invasive techniques and evaluations of herbal-based product in dermatology.

Permeation kinetics of active drugs through lanolin-based artificial membranes

Skin-penetration studies play an essential role in the selection of drugs for dermal or transdermal application. In vivo experiments in humans are not always possible for ethical, practical, or economic reasons, especially in the first part of the drug development. It is necessary to develop alternative methods using accessible and reproducible surrogates for in vivo human skin. The in vitro methodologies using biological membranes (human and animal skin) are recognized and well accepted as an alternative but present high inter- and intra-individual variability. Therefore, the formation of synthetic membranes has been studied to obtain skin- mimicking models for permeation studies. The aim of this work is to create lanolin-based artificial membranes that can mimic the absorption through the skin of compounds applied topically. A series of synthetic membranes using two different types of lanolin (water-extracted (WE) and solvent-extracted (SE)) were prepared. Next, the in vitro release test of three drugs (diclofenac sodium, ibuprofen and lidocaine) was performed on artificial membranes and on porcine skin placed on Franz cells. The percentage of release, flux, permeability coefficient, lag time, area under the curve, maximal concentration and time were determined for each compound in the different types of membrane. The results showed that lanolin membranes presented a strong diminution of permeability compared to most artificial membranes, leading to a very similar permeability to that of skin. The SE and WE membranes showed a diminution of transepidermal water loss and permeability of compounds compared with membranes alone. The results from WE membranes were similar to those found for the skin. The lanolin membranes were not capable of perfectly mimicking permeation through the skin, but they did have the same rank order of drug penetration as the skin. It may be deduced from these tests that these systems provide more reliable results for compounds with low to medium lipophilicity. The results demonstrated that new lanolin-based artificial membranes have the potential to be exploited as screening models for determining the permeability of a compound destined to be topically delivered.

The effect of various primers improving adhesiveness of gel polish hybrids on pH, TOWL and overall nail plates condition

BACKGROUND

Hybrid manicure is now a popular method of nail care and nail art, which is associated with its durability. Unfortunately, it has an adverse effect on pH, TOWL and overall nail plates condition and has not been investigated in detail so far.

AIMS

The aim of this study was to compare the pH and TOWL of the hand nails after using different primers. The effect of application time, breaks between applications and the method of curing and removal on those parameters and overall nail plates condition were evaluated.

PATIENTS/METHODS

An evaluation survey was conducted among 116 women. pH and TOWL measurements of the nail plate in 35 women were taken using the Courage & Khazaka. Clinical photos were made using the Fotomedicus system.

RESULTS

The measured pH values of the nail plate in the test group with gel polish hybrid on the nails were from 5.50 to 6.65, while after removal of the gel polish hybrid, the values ranged from 5.63 to 6.68. TOWL of the nail plate covered with gel polish hybrid ranged from 2.9 to 33.2 g/m² /h, whereas after removal of hybrids-from 1.9 to 45.7 g/m² /h.

CONCLUSION

Different forms of acid-free primers maintain a lower pH of the nail plate covered with a gel polish hybrid, while the acidic primer maintains higher values of the nail plate pH. The significant decrease in the nail plate TOWL following the application of gel polish hybrid indicates a reduced loss of water from the surface of the nail to the atmosphere.

Topical application of highly concentrated water-in-oil emulsions: Physiological skin parameters and skin penetration in vivo - A pilot study

Important aspects in the development of new dermal drug delivery systems are the formulations' physicochemical properties and stability. Moreover, their influence on skin physiology and their penetration performance in vivo are of crucial interest. We have recently developed novel concentrated water-in-oil emulsions based on a non-ionic silicone surfactant; the present study deals with the effect of these formulations on physiological skin parameters of healthy volunteers after repeated application. Variations in skin condition and barrier integrity were investigated using classical biophysical and spectroscopic techniques. After four weeks of continuous treatment, no signs of skin irritation could be observed. Both tested emulsions had a positive effect on skin properties despite their relatively high water content and low lipid content. In vivo tape stripping studies revealed penetrated amounts of the incorporated model drug fluorescein sodium of almost 50% of the applied dose, with a superior performance of emulsions with isopropyl myristate when compared to liquid paraffin. In summary, our study confirmed the suitability of the developed W/O emulsions for pharmaceutic and cosmetic applications.

Facial skin mapping: from single point bio-instrumental evaluation to continuous visualization of skin hydration, barrier function, skin surface pH, and sebum in different ethnic skin types

Dry skin is one of the most important concerns of consumers worldwide. Despite huge efforts over several decades, the personal care industry still does not offer a perfect solution to satisfy the unmet needs of consumers for moisturising treatments in different ethnic groups. The paucity of data for the underlying cellular and biochemical problems in, and the effects of moisturisers on photodamaged facial skin may partly explain this. Mainly, single point measurements are used to understand the effects of products on skin physiology even on surrogate skin sites such as the non‐photodamaged volar forearm. Some groups have developed discontinuous facial maps of skin biophysical properties, however, in 2014 a continuous facial analysis of bio‐instrumental evaluations was developed using a heat map approach. These maps enabled a continuous visualization of features that not only revealed an unexpected complexity of facial skin but also indicated that use of surrogate skin sites for facial skin is inappropriate. We have demonstrated that remarkable gradients of skin hydration, TEWL, skin surface pH and sebum exist within short distances across the face and the gradients are distinctive among different ethnic groups. In addition, these studies have demonstrated that darkly‐pigmented individuals do not necessarily have a better skin barrier function than their less‐pigmented counterparts and that Caucasians have a lower facial skin surface pH compared with more pigmented subjects. Overall, there are no correlations between capacitance, TEWL and skin surface pH including individual topology angle values. Novel 3D camera approaches have also been used to facilitate a more precise assignment of measurement sites and visualisation. The 3D facial colour mappings illustrated precisely the local moisturising effects of a moisturising cream. There were subtle ethnic differences in efficacy that may be related to underlying skin biochemistry and/or ethnic differences in product application. A placebo‐controlled study using conductance measurements in Chinese subjects is also reported. Finally, a new whole face statistical approach has been taken to prove differences in skin parameters but also of moisturiser treatment that adds further to our understanding of the ethnic differences in skin physiology and product application. This paper reviews the background of the development and application of this methodology.

New Insights into the Intrinsic and Extrinsic Factors That Shape the Human Skin Microbiome

Many studies have highlighted the importance of body site and individuality in shaping the composition of the human skin microbiome, but we still have a poor understanding of how extrinsic (e.g., lifestyle) and intrinsic (e.g., age) factors influence its composition. We characterized the bacterial microbiomes of North American volunteers at four skin sites and the mouth. We also collected extensive subject metadata and measured several host physiological parameters. Integration of host and microbial features showed that the skin microbiome was predominantly associated with demographic, lifestyle, and physiological factors. Furthermore, we uncovered reproducible associations between chronological age, skin aging, and members of the genus Corynebacterium. Our work provides new understanding of the role of host selection and lifestyle in shaping skin microbiome composition. It also contributes to a more comprehensive appreciation of the factors that drive interindividual skin microbiome variation.

Despite recognition that biogeography and individuality shape the function and composition of the human skin microbiome, we know little about how extrinsic and intrinsic host factors influence its composition. To explore the contributions of these factors to skin microbiome variation, we profiled the bacterial microbiomes of 495 North American subjects (ages, 9 to 78 years) at four skin surfaces plus the oral epithelium using 16S rRNA gene amplicon sequencing. We collected subject metadata, including host physiological parameters, through standardized questionnaires and noninvasive biophysical methods. Using a combination of statistical modeling tools, we found that demographic, lifestyle, and physiological factors collectively explained 12 to 20% of the variability in microbiome composition. The influence of health factors was strongest on the oral microbiome. Associations between host factors and the skin microbiome were generally dominated by operational taxonomic units (OTUs) affiliated with the Clostridiales and Prevotella. A subset of the correlations between microbial features and host attributes were site specific. To further explore the relationship between age and the skin microbiome of the forehead, we trained a Random Forest regression model to predict chronological age from microbial features. Age was associated mostly with two mutually coexcluding Corynebacterium OTUs. Furthermore, skin aging variables (wrinkles and hyperpigmented spots) were independently correlated to these taxa.

Enhancing SKIN health and safety in aged CARE (SKINCARE Trial): a study protocol for an exploratory cluster-randomized pragmatic trial

BACKGROUND

Aged long-term care receivers are affected by various adverse skin conditions like pressure ulcers, incontinence-associated dermatitis, dryness, intertrigo, and many more. Prevention of these skin problems and the provision of general hygiene and skin care activities are key areas of nursing practice. Numerous condition-specific guidelines are available and are implemented separately. On the other hand, there is huge overlap in terms of etiology, pathogenesis, and prevention of the skin conditions mentioned above. This leads to fragmented practice neglecting shared etiologies and prevention and treatment principles.

METHODS

The overall aims of this trial are to test the feasibility and to estimate possible effects of the implementation of a comprehensive skin care and prevention strategy targeting main nursing-relevant skin problems at the same time. A two-arm cluster-randomized controlled trial will be performed in 20 nursing homes randomly selected from the population of nursing homes of the state of Berlin, comparing skin care according to the skin care and prevention strategy with standard skin care.

DISCUSSION

It is expected that the implementation of this evidence-based skin care and prevention strategy will reduce the incidence of pressure ulcers, incontinence dermatitis, and other skin problems frequently related to care dependency. This trial will benefit individual patients and aged nursing home residents in general given the high prevalence and incidence of the addressed skin conditions. Findings of this exploratory trial may lay the foundation for a change in the development and evaluation of clinical standards and practices in general as it moves the perspective from individual conditions to a more comprehensive view on overlapping or coexisting health problems, in this case common skin conditions, in old-age long-term care receivers.

TRIAL REGISTRATION

The study is registered at the German Clinical Trials Register https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00015680 (Deutsches Register Klinischer Studien, or DRKS; registration number: DRKS00015680 , date of registration: January 29, 2019) and ClincialTrials.gov (registration number: NCT03824886 , date of registration: January 31, 2019).

Measurement of transepidermal water loss, stratum corneum hydration and skin surface pH in occupational settings: A review

BACKGROUND

The skin provides a permeable barrier which may be impaired in occupational settings. Transepidermal water loss (TEWL), stratum corneum hydration (SCH) and skin surface pH (SSpH) have been used in occupational settings to predict early onset of occupational skin diseases, to measure the effectiveness of prevention strategies for occupational skin diseases, and to assess skin condition during exposure. The aim was to compare the findings, identify shortcomings in the methodology and data reporting and furthermore, to make recommendations for future studies.

MATERIALS AND METHODS

A literature study was conducted on studies published before December 2018 to provide a review on the measurement of TEWL, SCH and SSpH in occupational settings.

RESULTS

TEWL, SCH and SSpH were previously measured in a wide variety of industries. Results between studies were highly variable, due to different study designs and different anatomical positions measured. Not all of the measurement conditions were reported and variations in study objectives led to data being reported and interpreted differently for most studies.

CONCLUSION

Incomplete reporting of methodology hinders comparison of bioengineering measurements. No bioengineering method has been proven useful as a predictive tool for occupational skin diseases, however, it is useful in the acute assessment of skin condition. It is recommended that future studies on TEWL, SCH and SSpH adhere to guidelines for occupational settings as far as possible to enable comparison between studies.

Stimulus Sensitive Smart Nanoplatforms: An Emerging Paradigm for the Treatment of Skin Diseases

Background:

Over the past century, the prevalence of skin diseases has substantially increased. These diseases present a significant physical, emotional and socio-economic burden to the society. Such conditions are also associated with a multitude of psychological traumas to the suffering patients. The effective treatment strategy implicates targeting of drugs to the skin. The field of drug targeting has been revolutionized with the advent of nanotechnology. The emergence of stimulus-responsive nanoplatforms has provided remarkable control over fundamental polymer properties for external triggers. This enhanced control has empowered pioneering approaches in the treatment of chronic inflammatory skin diseases.

Objective:

Our aim was to investigate the studies on smart nanoplatforms that exploit the altered skin physiology under diseased conditions and provide site-specific controlled drug delivery.

Method:

All literature search regarding the advances in stimulus sensitive smart nanoplatforms for skin diseases was done using Google Scholar and Pubmed.

Conclusion:

Various stimuli explored lately for such nano platforms are pH, temperature, light and magnet. Although, the scientists have actively taken up this research topic but there are still certain lacunaes associated which have been discussed in this review. Further, an interdisciplinary collaboration between the healthcare providers and pharmacists is a pivotal requirement for such systems to be available for patients.

Evaluation of structural damage and pH of nail plates of hands after applying different methods of decorating

BACKGROUND

The purpose of this study was to evaluate the effect of nail polish, gel polish hybrid, gel nail, and acrylic nail powder and the removal of these formulas on the nail plates properties, particularly the influence of different coatings on morphology and pH.

METHODS

The morphology and structure of nail plates were analyzed with use of scanning electron microscopy. The pH values of the nail plates of hands were measured using the system Courage & Khazaka.

RESULTS

The analysis of morphology and structure of the surface of nail plates showed distinct changes caused by decorative coatings. The most common ones include fragility and splitting of the nails. The pH value measured in the whole group ranged from 5.21 to 7.00.

CONCLUSIONS

The methods used to prepare nails for decoration and all methods of removing the applied preparations damage the healthy nail plates. The most common changes are brittleness and nail splitting. The nail polish remover causes less damage than acetone, and the use of a nail drill machine and nail file causes the greatest destruction of nail plates. The biggest effect on the pH change has the gel polish hybrid, gel nail, and acrylic nail powder, causing the pH value of nail plates to rise above 6.0, whereas after the application of the nail polish, the pH of the plates was on average 5.8 which is closest to the normal value, assumed as physiological.

Werner syndrome: quantitative assessment of skin aging

Background

Werner syndrome (WS) is a rare autosomal recessive disorder characterized by premature aging in adults. Although not sufficient to diagnose WS, persistent short stature and alteration of the dentition are among the few early signs that appear at puberty and can lead to a suspected diagnosis.

Objective

The study aimed at quantifying the signs of WS skin aging through biophysical parameters to find new parameters to be applied together with clinical observations in order to diagnose the disease early.

Patients and methods

The skin disorders induced by the disease were studied using noninvasive techniques: Tewameter TM300, Corneometer CM825, Skin-pH-Meter PH900, Mexameter MX16, Visioscan VC98, and Cutometer MPA580. Twenty-four patients divided into young group, WS group, and elderly group were recruited for the study.

Results

The WS skin is quite similar to aged skin, with some differences concerning the barrier function and skin elasticity; for instance, a WS patient of 30 years of age has the same skin roughness of a 50/60 years old subject with a more severe skin condition leading to higher dryness, high transepidermal water loss, and less distensibility correlating with skin indurations.

Conclusion

In patients with WS, the biophysical parameters can quantify the damage induced on the skin by the disease. In order to stage the degree of the disease, biophysical parameters could be used in the future as a diagnostic procedure in the initial stages of the disease as they may reveal lesions not yet clinically perceptible or in advanced stages.