Assessment of Intraday Variations in Skin Indentation Resistance.

INTRODUCTION: Information about the mechanical properties of skin and their changes with age and other conditions is important to help characterize skin physiology and pathological changes. One method to obtain this information is to measure the force required to indent the skin to a specified indentation depth (FORCE). This process measures the tissue's resistance to indentation or its compressibility and is related to the tissue's elastic modulus. Since such measurements are made in clinical and other settings at various times of day (TOD), it is useful to estimate the extent of intraday variations in FORCE that may be expected. This report focuses on this issue. METHOD: FORCE was self-measured on the volar forearm, 5 cm distal to the antecubital fossa, every two hours from 08:00 to 24:00 hours on two consecutive days by 12 medical students (six females and six males) who were trained in the measurement process using an indentation device (SkinFibroMeter). Variability in FORCE versus TOD was analyzed using the nonparametric Friedman test and differences between genders by the nonparametric Wilcoxon test. Differences between the first day (day 1) and the second day (day 2) were tested at each TOD. The whole-body fat percentage (FAT%) and water percentage (H2O%) were determined for each participant via bioimpedance measurements at 50 KHz. RESULTS: The age and BMI of the combined group (mean ± SD) were 24.5 ± 1.5 years and 23.2 ± 3.3 kg/m2. The overall average FORCE (mean ± SD) for the day over the 16 hours was 84.1 ± 22.7 mN and for day 2, it was 83.4 ± 28.5 mN with no significant difference between day 1 and day 2. For females, the overall two-day average FORCE (mean ± SD) over the 16 hours was 81.8 ± 20.3 mN and for males, it was 85.7 ± 30.1 mN with no significant difference between them (p = 0.271). Overall, there was no statistically significant difference in FORCE among TOD (p = 0.568). FORCE was not correlated with either FAT%, HTO%, or BMI. CONCLUSION: The findings indicate no statistically significant variation in indentation force in females, males, or combined concerning the TOD of the measurement or differences between consecutive days at corresponding times. This suggests that whether such measurements are done in a research setting or within a clinic, they can be done at various TOD with minimal expected variation for a given subject. However, an extension of these findings to persons with skin conditions or ages not herein evaluated must await further study.

Diversity of Asian skin: A review on skin biophysical properties.

Asian is home to dozens of different ethnic groups that are characterised by fascinating social and cultural variations. Unfortunately, existing literature on the skin properties of Asians tends to group this diverse population solely based on skin colour, perpetuating the misconception and stereotype that all Asian skin is the same. While Asia is one of the largest continents in the world, the difference in the geographical location and climate have long shaped the population into various ethnic groups with significant differences in the collective and diverse customs, traditions, cultures and living habits. The diverse ethnic groups in this region hint us that their skin biophysical characteristics can be very different from each other. This review features the profiling of the distinctive skin biophysical properties of Asians. We learn more about the different ethnic groups in Asia and acknowledge the unique skin biophysical properties even from the same country.

Biophysical and ultrasonographic changes of acute Old World cutaneous leishmaniasis skin lesions in comparison with uninvolved skin: A possible tool for non-invasive early detection and treatment outcome assessment.

Cutaneous leishmaniasis (CL) is a skin disease caused by intracellular protozoa, which is endemic in Iran. The goal of this study was to compare biophysical characteristics in CL lesions with uninvolved skin. Stratum corneum hydration, transepidermal water loss, surface friction, pH, sebum, melanin, erythema, temperature, elasticity parameters (R0, R2, and R5), thickness and echo-density of epidermis and dermis were measured on the active erythematous indurated part of a typical CL lesion in 20 patients, and compared with the same location on the other side of the body as control. Paired t-test was used for statistical analyses and a p < 0.05 was considered significant. Melanin content, R2 and echo-density of dermis were significantly lower, whereas transepidermal water loss, friction index, pH, erythema index, temperature, and the thickness of dermis were significantly higher in CL lesions. There was no significant difference in stratum corneum hydration, sebum, R0, R5, thickness of epidermis, and density of epidermis between CL and normal skin. CL lesions are characterized by certain changes in biophysical and ultrasonographic properties, which are mostly correlated with histological features. These changes are likely to be useful in the non-invasive early detection of CL and also as treatment outcome measures for clinical trials of new treatment modalities for CL in the future.

Skin biophysical properties including impaired skin barrier function determine ultraviolet sensitivity.

BACKGROUND: The levels of burning susceptibility to ultraviolet (UV) radiations are affected by various factors, including Fitzpatrick skin types, skin color, sex, and ethnicity. However, studies on the relationship between skin biophysical properties and erythemal responses to UV radiations are rare. OBJECTIVE: This study aimed to investigate biophysical properties of the skin that determined individual skin sensitivity to UV radiation. METHODS: As an indicator of skin sensitivity to UV radiation, Korean women were subjected to minimal erythema dose (MED) testing. The skin biophysical properties, such as skin hydration, transepidermal water loss (TEWL), were measured. MED were also evaluated in further variations in the skin, including barrier disruption. RESULTS: A significant negative correlation was observed between TEWL and MED. With an increase in TEWL, that represents reduced skin barrier function, skin UV sensitivity also increased. Artificial alteration of skin conditions also changed erythemal response to UV radiation. When the skin barrier was disrupted, MED significantly decreased, indicating increased skin UV sensitivity. It is hypothesized that the altered penetration of UV radiation into the stratum corneum under the respective skin conditions caused different erythema reactions. CONCLUSION: For the first time in a clinical study, the skin biophysical properties, including skin barrier function, were found to have significant effects on skin sensitivity to UV radiation. This finding could help predict individual susceptibility to UV damage. Therefore, skincare products that improve skin conditions associated with UV sensitivity, as well as sunscreen are important for protection against the hazards of UV radiation.

Changes in skin characteristics after using respiratory protective equipment (medical masks and respirators) in the COVID-19 pandemic among healthcare workers.

BACKGROUND: The coronavirus disease-2019 (COVID-19) outbreak has presented unique dermatologic challenges due to respiratory protective equipment (RPE)-related skin conditions. OBJECTIVE: To objectively evaluate the effects of RPE including medical masks and respirators on the skin barrier by measuring various physiological properties of the skin. METHODS: A cross-sectional study was designed. Twenty healthy healthcare workers were included in this study. Skin parameters including skin hydration, transepidermal water loss (TEWL), erythema, sebum secretion, pH, and skin temperature were measured in the RPE-covered and RPE-uncovered areas of the face 4 and 8 hours after wearing RPE and 14 hours after not wearing RPE. RESULTS: Skin hydration, TEWL, erythema, pH, and skin temperature increased in the RPE-covered areas after wearing RPE for 4 and 8 hours. By contrast, in the RPE-uncovered areas, skin hydration decreased and TEWL, erythema, and pH showed minimal changes over time. Based on the repeated-measure analysis, the changes in skin physiological properties over time were significantly different between RPE-covered and RPE-uncovered areas. CONCLUSION: We observed that skin physiological characteristics change with the prolonged use of RPE such as medical masks and respirators. These changes may lead to various adverse skin reactions after long-term use.