High resolution skin colorimetry, strain mapping and mechanobiology

The Pressurized Skin: A Review on the Pathological Effect of Mechanical Pressure on the Skin from the Cellular Perspective

Since human skin is the primary interface responding to external mechanical stimuli, extrinsic forces can disrupt its balanced microenvironment and lead to cutaneous lesions. We performed this review to delve into the pathological effects of mechanical pressure on skin from the cellular perspective. Fibroblasts of different subsets act as heterogeneous responders to mechanical load and express diverse functionalities. Keratinocytes relay mechanical signals through mechanosensitive receptors and the ensuing neurochemical cascades to work collaboratively with other cells and molecules in response to pressure. Mast cells release cytokines and neuropeptides, promoting inflammation and facilitating interaction with sensory neurons, while melanocytes can be regulated by pressure through cellular and molecular crosstalk. Adipocytes and stem cells sense pressure to fine-tune their regulations of mechanical homeostasis and cell differentiation. Applying mechanical pressure to the skin can induce various changes in its microenvironment that potentially lead to pathological alterations, such as ischemia, chronic inflammation, proliferation, regeneration, degeneration, necrosis, and impaired differentiation. The heterogeneity of each cellular lineage and subset from different individuals with various underlying skin conditions must be taken into consideration when discussing the pathological effects of pressure on the skin. Thus, elucidating the mechanotransduction and mechanoresponsive pathways from the cellular viewpoint is crucial in diagnosing and managing relevant dermatological disorders.

Do static and dynamic activities induce potentially damaging breast skin strain?

Background/Aim

This study aimed to quantify breast skin strain and strain rate and the effect of support garments at reducing strain and to determine characteristics that correlate with strain during static and dynamic activity.

Methods

39 women (UK size 32C to 36G) had electromagnetic sensors applied to their breast skin. Sensor coordinates were recorded while standing, walking, running, in no, low and high breast support conditions, plus bare-breasted in the estimated neutral position to calculate strain. Relative breast coordinates and 35 inter-sensor distances identified peak breast skin strain (%) and strain rate (%·s^-1), which were then correlated with nipple kinematics, breast pain and participant characteristics.

Results

Mean peak breast skin strain was generally <60% during standing, walking and running; however, some individuals exhibited 93% strain in bare-breasted running. Compared with low support, high support did not further reduce strain during standing and walking. Peak breast skin strain/strain rate location was longitudinal, in lateral and medial breast regions and displayed strong correlations with breast volume, body mass index and bust circumference.

Conclusion

Static and dynamic activity did not result in excessive breast skin strain, suggesting low risk of skin damage. However, during running, some individuals experienced excessive skin strains (up to 93%) and strain rates (up to 1258%·s^-1). Breast skin strain/strain rate location suggests lift is required in the lateral and medial bra cup to reduce strain, particularly in larger breast volumes due to increased skin strain risk.

Therapeutic targets in the management of striae distensae: A systematic review

BACKGROUND

Striae distensae are permanent dermal lesions that can cause significant psychosocial distress. A detailed understanding of the numerous treatment modalities available is essential to ensuring optimal patient outcomes.

OBJECTIVE

Our objective was to evaluate and summarize the different treatment methods for striae distensae by linking their proposed modes of action with the histopathogenesis of the condition to guide patient treatment.

METHODS

A systematic review of the literature was performed with no limits placed on publication date. Relevant studies were assigned a level of evidence by the authors.

RESULTS

Ninety-two articles were identified, with 74 being eligible for quality assessment. The majority of treatments aim to increase collagen production. The use of vascular lasers can reduce erythema in striae rubrae by targeting hemoglobin, whereas increasing melanin through methods such as ultraviolet light is a major focus for treatment of striae albae. Despite some topical treatments being widely used, uncertainty regarding their mode of action remains. No treatment has proved to be completely effective.

LIMITATIONS

Limitations of the study include low-quality evidence, small sample sizes, and varying treatment protocols and outcome measures, along with concerns regarding publication bias.

CONCLUSIONS

Further randomized, controlled trials are needed before definitive conclusions and recommendations can be made.

Photoprotection in specific populations: Children and people of color

Improved education on appropriate photoprotection in children is vital. Photoprotection for these individuals should include seeking shade, the use of physical agents (clothing, hat, sunglasses), and application of sunscreens on exposed areas. Avoidance of the use of tanning beds is an important component of education for teenagers. Ultraviolet radiation exposure induces DNA damage and photoaging in all skin types, including people of color. The extent of such damage is inversely related to constitutive skin pigmentation. Therefore, personalized photoprotection recommendations concerning skin cancer risk factors, desired treatment outcomes, health needs (eg, vitamin D), and photoaging based on the needs and preferences of the patient are essential. It is clear that additional research is needed on optimal levels of protection against ultraviolet radiation for people of color.

Topical management of striae distensae (stretch marks): prevention and therapy of striae rubrae and albae

Striae distensae (SD) are common dermal lesions, with significant physical and psychological impact. Many therapeutic modalities are available but none can completely eradicate SD. The most common therapy is the application of topicals used both therapeutically and prophylactically. Even though there are many commercially available topical products, not all have sufficient level of evidence to support their continued use in SD. The aim here was to assess the evidence for the use of topicals in SD and to propose a structured approach in managing SD. A systematic search of published literature and manufacturer website information for topicals in SD was carried out. The results showed that there are few studies (n = 11) which investigate the efficacy of topicals in management of SD. Trofolastin and Alphastria creams demonstrated level-2 evidence of positive results for their prophylactic use in SD. Additionally, tretinoin used therapeutically showed varying results whilst cocoa butter and olive oil did not demonstrate any effect. Overall, there is a distinct lack of evidence for each topical formulation. The majority of topicals failed to mention their effect on early vs. later stages of SD (striae rubrae compared to striae albae) and their role in both prevention and treatment. In conclusion, there is no topical formulation, which is shown to be most effective in eradicating or improving SD. A structured approach in identification and targeted management of symptoms and signs with the appropriate topical is required. Randomized controlled trials are necessary to assess the efficacy of topical products for treatment and prevention of different stages of SD.

Characterization and stability studies of emulsion systems containing pumice

Emulsions are the most common form of skin care products. However, these systems may exhibit some instability. Therefore, when developing emulsions for topical application it is interesting to verify whether they have suitable physical and mechanical characteristics and further assess their stability. The aim of this work was to study the stability of emulsion systems, which varied in the proportion of the emulsifying agent cetearyl alcohol (and) sodium lauryl sulfate (and) sodium cetearyl sulfate (LSX), the nature of the oily phase (decyl oleate, cyclomethicone or dimethicone) and the presence or absence of pumice (5% w/w). While maintaining the samples at room temperature, rheology studies, texture analysis and microscopic observation of formulations with and without pumice were performed. Samples were also submitted to an accelerated stability study by centrifugation and to a thermal stress test. Through the testing, it was found that the amount of emulsifying agent affects the consistency and textural properties such as firmness and adhesiveness. So, formulations containing LSX (5% w/w) and decyl oleate or dimethicone as oily phase had a better consistency and remained stable with time, so exhibited the best features to be used for skin care products.