Bioengineering and subjective approaches to the clinical evaluation of dry skin

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.

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.

[Dermoscopy of genodermatoses]

Genodermatoses are a group of inherited skin diseases whose diagnosis is challenging due to their rarity as well as their clinical and genetic diversity. The majority of genodermatoses are autosomal or X‑linked inherited, but mosaic forms are also observed. Genodermatoses comprise various phenotypes ranging from limited cutaneous disease to severe cutaneous and extracutaneous involvement and may also be early warning signs of a multisystemic disorder. Despite recent advances in genetic technology and skin imaging modalities, dermoscopy can be useful for screening, diagnosis, and treatment follow-up. In ectopic mineralization and lysosomal storage disorders (pseudoxanthoma elasticum and Fabry disease, respectively), cutaneous manifestations may indicate involvement of other organs. In keratinization diseases (e.g., ichthyoses) and acantholytic skin fragility disorders (e.g., Darier and Hailey-Hailey disease), dermoscopy may help to assess treatment response by visualizing background erythema, hyperkeratosis, and interkeratinocyte space prominence. Dermoscopy is a noninvasive, easily accessible, useful, in vivo assessment tool that is well established in dermatology to recognize characteristic features of genodermatoses.

Biophysical and Subject-Based Assessment of the Effects of Topical Moisturizer Usage on Xerotic Skin—Part II: Visioscan® VC 20plus Imaging

As new biophysical methods become available to the skin researcher it is important to understand the type of information that they are capable of measuring, and how it relates to consumer perception of topical moisturizing products. The aim of the work presented here was to understand what dry skin imaging can reveal about the skin and subject feedback from the use of a topical moisturizing product and how it relates to the consumer usage experience of a topical product. Images from a dry skin camera—the Visioscan® VC 20plus—during 3 weeks in vivo usage of a topical moisturizing product were analyzed. Subject feedback regarding their skin condition was also collected. Strong statistical improvements (p < 0.05) were observed for a wide range of skin parameters derived from the Visioscan® VC 20plus. Skin scaliness and smoothness and parameters associated with skin health and appearance (surface, energy, contrast, homogeneity) improved as a result of topical product usage. Subjects reported their skin to feel less dry, to be smoother, and more supple and to look and feel healthier after product usage. The length of time until they felt the need to re-apply the product increased during the study.

Fourier transform infrared absorption (FTIR) on dry stratum corneum, corneocyte-lipid interfaces: experimental and vibrational spectroscopy calculations

Many questions concerning the biophysical and physiological properties of skin are still open. Skin aging, permeability, dermal absorption, hydration, and drug transdermal delivery, are few examples of processes with unveiled underlying mechanisms. In this work, it is presented a comparison between Fourier transform infrared absorption (FTIR) of dry stratum corneum and stratum corneum under lipase action supported by first-principles density functional vibrational calculations. The molecular structure of stratum corneum was modeled by an archetype of its hygroscopic proteic portion inside the corneocytes, the natural moisturizing factor, coupled to glycerol molecules which represent the lipid fraction of stratum corneum. Vibrational spectra were calculated and compared to experimental data obtained on the animal model of stratum corneum. The experimental results indicated prominent spectral differences between dry and lipase-treated stratum corneum. Principal components analysis and hyerarchical clustering indicated that 1200, 1650, and 1695 cm^-1 bands are the most influential on the discrimination. It is noticed that bands in the fingerprint region (800-1800 cm^-1) were correctly assigned. Moreover, the calculations revealed the existence of two coupled vibration between the hydroxyl group of lipid and methylene (1120 and 1160 cm^-1), which are of special interest since they probe the lipid-amino acid coupling. The model was also able to predict the shear modulus of dry stratum corneum in excellent agreement with the reported values from the literature. Other physical/chemical properties could be calculated exploring the chemical accuracy and molecular resolution of this model. Research in dermatology, cosmetology, and biomedical engineering in the specific topics of drug delivery and/or mechanical properties of skin are examples of fields that would potentially take advantage of this approach.

Safety and efficacy of Sclerocarya birrea (A.Rich.) Hochst (Marula) oil: A clinical perspective

ETHNOPHARMACOLOGICAL RELEVANCE

Sclerocarya birrea (A.Rich.) Hochst (Marula) nut oil is a popular ingredient in cosmetics such as skin lotions, lipsticks and foundations. The demand for this African oil increased tremendously such that in 2008 almost US$ 20 million was spent on Marula oil for cosmetic product manufacturing. The ethnobotanical literature states that the Zulu people in South Africa amongst others applied the oil to maintain a healthy skin. Scientific studies to support the traditional use as well as the inclusion of Marula oil in cosmetic products is lacking. This study evaluated the irritancy potential (safety), the moisturising and hydrating effects as well occlusivity properties (efficacy) of Marula oil after topical application. In addition, the Marula oil used in this study was comprehensively characterised using two-dimensional gas chromatography coupled to mass spectrometry.

METHODS AND MATERIALS

Quantification of the fatty acid methyl esters (FAMEs) was done using a LECO Pegasus 4D GC × GC-MS. To determine the safety and efficacy of Marula oil healthy caucasian adult female volunteers (n = 20) who complied with the inclusion and exclusion criteria for the irritancy patch, moisture efficacy, hydrating and occlusivity tests were recruited for each study. A 2 × magnifying lamp (visual observation), Chromameter®, Aquaflux® and Corneometer® instruments were used to evaluate and monitor the irritancy level, skin barrier function, transepidermal water loss, hydrating and occlusive effects of topically applied Marula oil.

RESULTS

The GC × GC-MS analysis identified several saturated as well as unsaturated fatty acids. Oleic acid was the major fatty acid constituting 69.0% of the oil followed by palmitic acid (15.3%), linoleic acid (9.2%), palmitoleic acid (4.1%) and stearic acid (1.5%). The clinical study revealed that Marula oil is non-irritant (p < 0.001), with moisturising and hydrating properties (p < 0.001) when applied to a lipid-dry (xerosis) skin. Additionally the oil exhibited occlusive effects (p < 0.001) when applied to normal skin. These findings may be linked to the absorption of the oil into the skin due to the high percentage of oleic acid and the presence of palmitic acid which are known to disturb the stratum corneum intercellular lipids. These fatty acids present in Marula oil are very similar to those present in the epidermis, and can be considered biomimetic.

CONCLUSIONS

Marula oil rich in fatty acids exhibits moisturising, hydrating and occlusive properties. As the oil is non-irritating and provides a moisturising effect with moderate prevention of transepidermal water loss, average moisture retention properties and noteworthy occlusive effects, its inclusion in cosmetic products based on its traditional use may be justified depending on the application.

Full-depth epidermis tomography using a Mirau-based full-field optical coherence tomography

With a Gaussian-like broadband light source from high brightness Ce(3+):YAG single-clad crystal fiber, a full-field optical coherence tomography using a home-designed Mirau objective realized high quality images of in vivo and excised skin tissues. With a 40 × silicone-oil-immersion Mirau objective, the achieved spatial resolutions in axial and lateral directions were 0.9 and 0.51 μm, respectively. Such a high spatial resolution enables the separation of lamellar structure of the full epidermis in both the cross-sectional and en face planes. The number of layers of stratum corneum and its thickness were quantitatively measured. This label free and non-invasive optical probe could be useful for evaluating the water barrier of skin tissue in clinics. As a preliminary in vivo experiment, the blood vessel in dermis was also observed, and the flowing of the red blood cells and location of the melanocyte were traced.

Hydration effects on the barrier function of stratum corneum lipids: Raman analysis of ceramides 2, III and 5

The stratum corneum is the outermost layer of the skin; its barrier function is highly dependent on the composition and the structure as well as the organization of lipids in its extracellular matrix. Ceramides, free fatty acids and cholesterol represent the major lipid classes present in this matrix. They play an important role in maintaining the normal hydration levels required for the normal physiological function. Despite the advancement in the understanding of the structure, composition and the function of the stratum corneum (SC), the concern of "dry skin" remains important in dermatology and care research. Most studies focus on the quantification of water in the skin using different techniques including Raman spectroscopy, while the studies that investigate the effect of hydration on the quality of the barrier function of the skin are limited. Raman spectroscopy provides structural, conformational and organizational information that could help elucidate the effect of hydration on the barrier function of the skin. In order to assess the effect of relative humidity on the lipid barrier function; we used Raman spectroscopy to follow-up the evolution of the conformation and the organization of three synthetic ceramides (CER) differing from each other by the nature of their polar heads (sphingosine, phytosphingosine and α hydroxyl sphingosine), CER 2, III and 5 respectively. CER III and 5 showed a more compact and ordered organization with stronger polar interactions at intermediate relative humidity values, while CER 2 showed opposite tendencies to those observed with CER III and 5.

Moisturizing effect of a cosmetic formulation containing pequi oil (Caryocar brasiliense) from the Brazilian cerrado biome

Caryocar brasiliense, popularly known in Brazil as “pequi”, is a species widely distributed in the Brazilian Cerrado. The seeds are surrounded by a woody endocarp coated with a yellow fleshy mesocarp rich in oil and vitamin A, whose oil has a useful role in the treatment of skin aging and protection of human skin against UV-induced damage and skin hydration. The aim of this study was to evaluate the effect of cosmetic formulations containing pequi oil (Caryocar brasiliense) on skin hydration, after a single application. Hydration effect assessment was performed by applying the formulations under study (Control – no formulation, vehicle, and vehicle + pequi oil) onto forearm skin of 30 human volunteers. Skin capacitance and Transepidermal Water Loss (TEWL) measurements were analyzed before, and at 1, 2 and 3 hours after, a single application. Evaluation results of a single application of the vehicle containing pequi oil showed an increase in stratum corneum water content, indicating a skin moisturizing effect. Results of the evaluation of immediate effects of TEWL demonstrated that the vehicle containing pequi oil significantly increased skin moisture during the 3 h evaluation period. The formulations containing pequi oil showed clinical efficacy, increasing stratum corneum water content and enhancing skin barrier function.

Raman spectroscopy: in vivo quick response code of skin physiological status

Dermatologists need to combine different clinically relevant characteristics for a better understanding of skin health. These characteristics are usually measured by different techniques, and some of them are highly time consuming. Therefore, a predicting model based on Raman spectroscopy and partial least square (PLS) regression was developed as a rapid multiparametric method. The Raman spectra collected from the five uppermost micrometers of 11 healthy volunteers were fitted to different skin characteristics measured by independent appropriate methods (transepidermal water loss, hydration, pH, relative amount of ceramides, fatty acids, and cholesterol). For each parameter, the obtained PLS model presented correlation coefficients higher than R2=0.9. This model enables us to obtain all the aforementioned parameters directly from the unique Raman signature. In addition to that, in-depth Raman analyses down to 20 μm showed different balances between partially bound water and unbound water with depth. In parallel, the increase of depth was followed by an unfolding process of the proteins. The combinations of all these information led to a multiparametric investigation, which better characterizes the skin status. Raman signal can thus be used as a quick response code (QR code). This could help dermatologic diagnosis of physiological variations and presents a possible extension to pathological characterization.

Does massage postapplication improve moisturizer's efficacy? A 2-week regression study

BACKGROUND

Combining massage with moisturizer application is a popular technique in beauty spa sessions. The subjective positive psychological effects of massage with moisturizer application in hand and face beauty treatment are documented by many people attending spa sessions. The aim of this study was to objectively evaluate the effect of local effleurage massage as an external intervention on moisturizer efficacy.

METHODS

In a regression-type study of 2-week, twice-daily application followed by 1 week of regression, 13 female subjects applied "off the shelf" moisturizer twice daily on both forearms followed by 1 min superficial massage for one forearm randomized among subjects. The influence of massage after moisturizer application on skin barrier properties was evaluated by noninvasive measurements of transepidermal water loss (TEWL), skin capacitance, and skin elasticity at baseline, day 7, and day 14 during the treatment phase, and day 21 following a 1-week regression period, in which no moisturizer and no massage were performed on forearms.

RESULTS

The tested "off the shelf" moisturizer in both "massage" and "no-massage" application protocols caused a comparable progressive improvement in skin hydration level and barrier permeability over the 2-week treatment period, which was maintained during the 1-week regression (no moisturizer) period. In addition, skin elasticity was similarly improved by both application protocols.

CONCLUSION

In this long-term study, the daily performance of massage after moisturizer application was not an effective external intervention for enhancing moisturizer efficacy.