Mechanical properties of human forearm and vulvar skin

Water flow elastography - A promising tool to measure tissue stiffness during minimally invasive surgery

Mechanical properties are important markers for pathological processes in tissue. Elastography techniques are therefore becoming more and more useful for diagnostics. In minimally invasive surgery (MIS), however, the probe size is limited and the handling is restricted, thereby excluding the application of most established elastography techniques. In this paper we introduce water flow elastography (WaFE) as a new technique that benefits from a small and inexpensive probe. This probe flows pressurized water against the sample surface to locally indent it. The volume of the indentation is measured with a flow meter. We use finite element simulations to find the relation between the indentation volume, the water pressure, and the Young's modulus of the sample. We used WaFE to measure the Young's modulus of silicone samples and porcine organs, finding agreement within 10% to measurements with a commercial material testing machine. Our results show that WaFE is a promising technique for providing local elastography in MIS.

Palmar skin elasticity measured by the Cutometer MPA 580 is decreased in mild Dupuytren's disease compared to healthy controls

Introduction

Involvement of the palmar skin is often seen in patients with Dupuytren's disease (DD) with severe finger contractures. However, skin elasticity may be already decreased earlier in the disease. The Cutometer MPA 580 could provide an objective skin measurement tool to assess this decrease in elasticity. Linking objective skin measurements to functional outcome measures could lead to better prediction of disease progression. We set up a study to investigate if the Cutometer was able to detect differences in skin elasticity between patients with mild Dupuytren's disease and healthy controls.

Methods

A cross-sectional analytical study was performed. Three assessors measured skin elasticity (palmar hand) on two sites using the Cutometer on 30 patients with mild DD and 30 healthy controls. Student's t-test was used to evaluate differences in skin elasticity and a linear model to evaluate interactions between the groups and sites.

Results

Significant differences in skin elasticity were found between DD patients and controls, as well as differences based on the location examined.

Discussion

Similar to other skin conditions, the Cutometer MPA 580 was able to demonstrate a significant lower elasticity in the palmar skin in DD patients compared to healthy controls. A decrease in skin elasticity in different locations of the hand correlated with areas that often pose problems in the treatment of more severe DD. The Cutometer could potentially be a tool to identify these areas earlier in the disease.

The Structure of Human Sebaceous Glands and Its Relation to Skin Viscoelasticity

High-frequency ultrasound has realized high-resolution observation of deep part of the dermis in vivo. The size of sebaceous glands was evaluated by three-dimensional ultrasound microscopy with the ultrasonic frequency of 120 MHz. The viscoelasticity of the same regions was measured by well-established biomechanical equipment. There was no significant difference between the size of sebaceous glands in cheek and forearm. The skin's ability to recover to its initial position after deformation was significantly higher in forearm than in cheek. Both sizes of sebaceous glands in cheek and forearm were positively correlated with the parameter of viscoelasticity. The size of the sebaceous glands in the deep part of the dermis can be a parameter of skin viscoelasticity. High-frequency ultrasound imaging contributes to the evaluation of human skin morphology as well as functions.

Aloe sterol supplementation improves skin elasticity in Japanese men with sunlight-exposed skin: a 12-week double-blind, randomized controlled trial

Background/objective

Recently, it was confirmed that the daily oral intake of plant sterols of Aloe vera gel (Aloe sterol) significantly increases the skin barrier function, moisture, and elasticity in photoprotected skin. This study aimed to investigate whether Aloe sterol intake affected skin conditions following sunlight exposure in Japanese men.

Methods

We performed a 12-week, randomized, double-blind, placebo-controlled study to evaluate the effects of oral Aloe sterol supplementation on skin conditions in 48 apparently healthy men (age range: 30–59 years; average: 45 years). The subjects were instructed to expose the measurement position of the arms to the sunlight outdoors every day for 12 weeks. The skin parameters were measured at 0 (baseline), 4, 8, and 12 weeks.

Results

Depending on the time for the revelation of the sunlight, the b* value and melanin index increased and the skin moisture decreased. After taking an Aloe sterol tablet daily for 12 weeks, the skin elasticity index (R2, R5, and R7) levels were significantly higher than the baseline value. There were no differences between the groups in these skin elasticity values. In the subgroup analysis of subjects aged <46 years, the change in the R5 and R7 was significantly higher in the Aloe group than in the placebo group at 8 weeks (P=0.0412 and P=0.0410, respectively). There was a difference in the quantity of sun exposure between each subject, and an additional clinical study that standardizes the amount of ultraviolet rays is warranted. No Aloe sterol intake-dependent harmful phenomenon was observed during the intake period.

Conclusion

Aloe sterol ingestion increased skin elasticity in the photodamaged skin of men aged <46 years.

Biomechanical properties of infantile hemangiomas: clinical stage and effect of age

BACKGROUND

Infantile hemangiomas (IHs) are benign vascular neoplasms with rapid capillary proliferation shortly after birth and slow involution with diminishing capillary proliferative activity, fibrosis, and fatty replacement over 7-10 years.

METHODS

Hemangiomas and contralateral control sites in 88 subjects were measured using a suction device, 6-mm probe and 200 mbar negative pressure. Mechanical properties were assessed vs. controls and effects of body site, depth, clinical stage, histology diagnosis, and time.

RESULTS

Biological elasticity, overall elasticity, net elasticity, total recovery, and elastic recovery were lower for IH vs. controls (P < 0.001). IH total deformation, elastic deformation, viscoelastic creep, and residual deformation were higher than controls (P < 0.001). Involuting IHs had lower viscoelasticity than proliferating and stable lesions (P < 0.001) and lower viscoelastic creep than stable IHs (P = 0.04). IH viscoelasticity was higher at 2.3 than 12.9, 23.7, and 61.0 months and at 4.9 and 8.1 than 61.0 months. IH elastic recovery varied by body site with larger differences vs. control for abdomen and leg. Elastic recovery differences from control were smaller at younger vs. older ages.

CONCLUSIONS

Measurement of biomechanical properties may be useful to characterize IH progression and treatment response in clinical settings.

Objective evaluation of the effect of autologous platelet concentrate on post-operative scarring in deep burns

INTRODUCTION

The healing of grafted areas after surgical treatment of deep burns frequently generates mutilating scars, and rises the risk of subsequent scar hypertrophy. Scar assessment based on clinical evaluation is inherently subjective, which stimulates search for objective means of evaluation.

OBJECTIVE

The aim of this study was to objectively evaluate the effect of using autologous platelet concentrate (APC) in combination with split thickness skin grafting (STSG) on scarring processes following surgery of deep burns as compared with application of STSG alone.

METHOD

Selected viscoelastic properties of 38 scars on 23 patients in total were examined using the Cutometer MPA 580 under controlled conditions for long-term outcomes 1, 3, 6 and 12 months after surgery following deep burns.

RESULTS

The findings of this study suggest that the STSG+APC combination reduces the time of scar viscoelastic properties recovery as compared with application of STSG alone. This was statistically significant for viscoelastic parameters R2 and Q1.

CONCLUSION

APC has been advocated to enhance scarring after surgery of deep dermal and full thickness burns. We objectively demonstrated that the viscoelastic properties of scars treated with STSG+APC combination return more rapidly to the plateau state than areas treated with STSG only.

Effect of compositions in nanostructured lipid carriers (NLC) on skin hydration and occlusion

Purpose

To study the effects of varying lipid concentrations, lipid and oil ratio, and the addition of propylene glycol and lecithin on the long-term physical stability of nanostructured lipid nanocarriers (NLC), skin hydration, and transepidermal water loss.

Methods

The various NLC formulations (A1–A5) were prepared and their particle size, zeta potential, viscosity, and stability were analyzed. The formulations were applied on the forearms of the 20 female volunteers (one forearm of each volunteer was left untreated as a control). The subjects stayed for 30 minutes in a conditioned room with their forearms uncovered to let the skin adapt to the temperature (22°C ± 2°C) and humidity (50% ± 2%) of the room. Skin hydration and skin occlusion were recorded at day one (before treatment) and day seven (after treatment). Three measurements for skin hydration and skin occlusion were performed in each testing area.

Results

NLC formulations with the highest lipid concentration, highest solid lipid concentration, and additional propylene glycol (formulations A1, A2, and A5) showed higher physical stability than other formulations. The addition of propylene glycol into an NLC system helped to reduce the particle size of the NLC and enhanced its long-term physical stability. All the NLC formulations were found to significantly increase skin hydration compared to the untreated controls within 7 days. All NLC formulations exhibited occlusive properties as they reduced the transepidermal water loss within 7 days. This effect was more pronounced with the addition of propylene glycol or lecithin into an NLC formulation, whereby at least 60% reduction in transepidermal water loss was observed.

Conclusion

NLCs with high lipid content, solid lipid content, phospholipid, and lecithin are a highly effective cosmetic delivery system for cosmetic topical applications that are designed to boost skin hydration.

Suppression of UV-induced wrinkle formation by induction of HSP70 expression in mice

UV-induced wrinkle formation owing to the degeneration of the extracellular matrix (ECM) is a major dermatological problem in which abnormal activation of matrix metalloproteinases (MMPs) and elastases have important roles. Heat shock protein 70 (HSP70) has cytoprotective and anti-inflammatory activities. In this study, we examined the effect of HSP70 expression on UV-induced wrinkle formation. Mild heat treatment (exposure to heated water at 42 °C) of the dorsal skin of hairless mice induced the expression of HSP70. The long-term repeated exposure to UV induced epidermal hyperplasia, decreased skin elasticity, degeneration of ECM, and wrinkle formation, which could be suppressed in mice concomitantly subjected to this heat treatment. The UV-induced epidermal hyperplasia, decreased skin elasticity, and degeneration of ECM were less apparent in transgenic mice expressing HSP70 than in wild-type mice. UV-induced fibroblast cell death, infiltration of inflammatory cells, and activation of MMPs and elastase in the skin were also suppressed in the transgenic mice. This study provides evidence for an inhibitory effect of HSP70 on UV-induced wrinkle formation. The results suggest that this effect is mediated by various properties of HSP70, including its cytoprotective and anti-inflammatory activities. We propose that HSP70 inducers used in a clinical context could prove beneficial for the prevention of UV-induced wrinkle formation.

Confocal laser scanning microscopy evaluation of an acellular dermis tissue transplant (Epiflex®)

The structure of a biological scaffold is a major determinant of its biological characteristics and its interaction with cells. An acellular dermis tissue transplant must undergo a series of processing steps, to remove cells and genetic material and provide the sterility required for surgical use. During manufacturing and sterilization the structure and composition of tissue transplants may change.

The composition of the human cell-free dermis transplant Epiflex® was investigated with specific attention paid to its structure, matrix composition, cellular content and biomechanics.

We demonstrated that after processing, the structure of Epiflex remains almost unchanged with an intact collagen network and extracellular matrix (ECM) protein composition providing natural cell interactions. Although the ready to use transplant does contain some cellular and DNA debris, the processing procedure results in a total destruction of cells and active DNA which is a requirement for an immunologically inert and biologically safe substrate. Its biomechanical parameters do not change significantly during the processing.

High-resolution ultrasound imaging of human skin in vivo by using three-dimensional ultrasound microscopy

Observing the morphology of human skin is important in the diagnosis of skin cancer and inflammation and in the assessment of skin aging. High-frequency ultrasound imaging provides high spatial resolution of the deep layers of the skin, which cannot be visualized by optical methods. The objectives of the present study were to develop a three-dimensional (3-D) ultrasound microscope and to observe the morphology of normal human skin in vivo. A concave polyvinylidene fluoride transducer with a central frequency of 120 MHz was excited using an electric pulse generated by semiconductor switching. The transducer was scanned two-dimensionally by using two linear motors on the region-of-interest and the ultrasonic reflection was digitized with 2-GHz sampling. Consecutive B-mode images perpendicular to the skin surface were reconstructed to generate multiplanar reconstructed images and 3-D volume-rendering images clearly showing microstructures such as sebaceous glands and hair follicles. The 3-D ultrasound microscope could be used to successfully image the morphology of human skin noninvasively and may provide important information on skin structure.

Tretinoin cyclodextrin complex (RA/CyD) causes less irritation with an equal antiwrinkle effect compared with conventional tretinoin: clinical and histologic studies of photoaged skin

BACKGROUND

Topical tretinoin [all-trans-retinoic acid (RA)] currently is widely used to treat photoaged skin. However, undesirable side effects such as erythema, irritation, and scaling are unavoidable and limit the use of tretinoin. To address these issues, the authors developed the tretinoin cyclodextrin complex (RA/CyD), which is tretinoin encapsulated by cyclodextrin. Cyclodextrins are cyclic oligosaccharides commonly used in food additives and fabric fresheners. This study aimed to evaluate the antiwrinkle effect of RA/CyD and alleviation of the side effects compared with RA treatment alone.

METHODS

In this study, 12 photoaged patients completed an 8 week study using RA and RA/CyD in a double-blind manner. Before and after the treatment, the patients' evaluations, wrinkle scores, skin elasticity, and wrinkle area measurement using skin replica were evaluated. Three men were recruited for histologic analysis.

RESULTS

The patients reported that undesirable irritant reactions were more moderate with RA/CyD than with RA. In the assessment of wrinkle scores, skin elasticity, and wrinkle area measurement, RA/CyD demonstrated an antiwrinkle effect statistically equal to that of RA. In histology, both RA/CyD and RA demonstrated epidermal hyperplasia. In immunohistochemistry, inflammation induced by RA/CyD was more moderate than that induced by RA.

CONCLUSION

The findings show that RA and RA/CyD result in the equivalent clinical improvement for patients with photoaging. The use of RA/CyD overcomes the drawbacks of RA while possessing equal effect. It is expected that CyD will broaden tretinoin treatment.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors at www.springer.com/00266.

Improvement of skin quality using a new collagen scaffold in acute burns and reconstructive surgery: an in vivo evaluation of split skin graft transplantation in a rat model

INTRODUCTION

Split-thickness skin grafting is often associated with poor skin quality. In this context, a new collagen cell carrier (CCC), as an underlayment in split skin graft (SSG) transplantation for covering tissue defects in rats, has been evaluated as an improving agent.

METHODS

Twenty-eight full-thickness wounds were covered with SSGs, applying the CCC as an underlayment in 14 rats and using SSG transplantation alone in control group. Postgraft skin areas were assessed using an instrument that measures mechanical properties of skin. Three parameters were considered for skin elasticity analysis: total skin deviation (R0), gross elasticity (R2) and viscoelasticity (R8). Measurements were performed every 10 days for 80 days after grafting. Biopsies were taken subsequently for histologic evaluation.

RESULTS

The results demonstrated significantly superior elasticity values in CCC-supplemented SSGs in terms of gross elasticity and viscoelasticity (R2/R8) starting from day 60 after grafting to the end of the measuring period. There was no histologic evidence of inflammation, adverse host tissue reaction, or scar tissue formation.

CONCLUSION

Split skin grafting is associated with poor dermal quality, but CCC may offer unique opportunities in complex wound management in terms of skin graft quality improvement.

Imaging of sebaceous glands of human skin by three-dimensional ultrasound microscopy and its relation to elasticity

High frequency ultrasound imaging has realized high resolution in vivo imaging of the biological tissues at a microscopic level. Human skin structure, especially sebaceous glands at the deep part of the dermis, was observed by three-dimensional ultrasound microscopy with the central frequency of 120 MHz. The visco-elasticity and surface sebum level of the observed region were measured by established testing devices. Both sebaceous glands density and surface sebum level were higher in cheek than those in forearm. The viscosity of forearm was lower than that of cheek. These results suggest that sebaceous glands may act as cushions of the skin besides their classical role of secreting sebum and some hormones. High frequency ultrasound imaging contributes to the evaluation of human skin aging.

In vitro and in vivo skin anti-aging evaluation of gel containing niosomes loaded with a semi-purified fraction containing gallic acid from Terminalia chebula galls

CONTEXT

The galls of Terminalia chebula Retz. (Combretaceae) frequently appear in many Thai Lanna medicinal plant recipes for promotion of longevity.

OBJECTIVE

The objective of this study was to evaluate the skin anti-aging of gel containing niosomes loaded with a semi-purified fraction containing gallic acid from T. chebula galls.

METHOD

The semi-purified fraction containing phenolic compounds including gallic acid isolated from T. chebula galls loaded in non-elastic or elastic niosomes, and its developed gel, were evaluated for rabbit skin irritation by the closed patch test and skin anti-aging in human volunteers by measuring skin elasticity and roughness.

RESULTS

Gel containing the fraction unloaded (SS) or loaded in non-elastic (SN) or elastic (SE) niosomes and gallic acid loaded in non-elastic (GN) or elastic (GE) niosomes showed no skin irritation, whereas the unloaded gallic acid (GS) gave the irritation in rabbit's skin by the closed patch test. The % parameter changes of skin elastic recovery and skin elastic extension when applied with SN and SE gels were +28.73 and +32.57; -21.25 and -22.63%, respectively. SN and SE gel also showed a significant decrease of the maximum and average roughness values with the parameter changes of -29.43 and -32.38; -39.47 and -35.28%, respectively.

CONCLUSION

The semi-purified fraction loaded in niosomes indicated not only higher chemical stability of gallic acid containing in the fraction, but also more in vivo anti-aging activities than the unloaded fraction when incorporated in gel.

Objective scar assessment tools: a clinimetric appraisal

BACKGROUND

Scars may lead to an array of cosmetic, psychological, and functional problems. Different scar features can be distinguished (i.e., color, thickness, relief, pliability, and surface area) that are clinically relevant and contribute to the quality and judgment of a scar. Today, objective evaluation of these scar features is indispensable for practicing evidence-based medicine (e.g., to evaluate the outcome of clinical trials). In this review, an overview and update are given on the most relevant noninvasive objective measurement tools for scar evaluation.

METHODS

A PubMed literature search was performed. Articles evaluating the clinimetric properties of noninvasive scar assessment tools were included. The selected objective measurement tools were then critically reviewed with respect to the clinimetric properties of reliability, validity, and feasibility.

RESULTS

In total, 75 articles were selected and 23 different noninvasive measurement methods were evaluated.

CONCLUSION

Based on the scar features color, thickness, relief, pliability, and surface area, the best measurement tools that are currently available were recommended.

The characteristics of aromatase deficient hairless mice indicate important roles of extragonadal estrogen in the skin

The roles of extragonadal estrogen in the skin are poorly understood, due to the lack of proper animal models. We examined the skin phenotypes of aromatase-knockout hairless (ArKO) mice and wild-type hairless (WT) mice, both of which were obtained through crossbreeding of Ar+/- mice and hairless mice. Differences in the skins of ArKO and WT mice were compared with those of ovariectomized (OVX) and control (Sham) mice. A difference was observed in the skin tone of ArKO mice, which is pale white and differs from the pinkish tone of all other mice. However, both ArKO and OVX mice similarly exhibited deteriorations of skin properties as compared to their respective controls. Furthermore, all the deteriorations were similarly amplified by chronic UVB irradiation in both ArKO and OVX mice as compared to their respective controls. The unique skin phenotype of ArKO mice was observed in sunburn reactions. Specifically, skins of ArKO mice showed no reaction after an acute UVB irradiation at dose intensities caused sunburn in others. However, follow-up observation found delayed reactions associated with brownish skin color and swelling only in ArKO mice, thereby suggesting that the role of extragonadal estrogen may be connected with the protective reactions of skin.

Estimating material parameters of human skin in vivo

An accurate mathematical representation of the mechanical behaviour of human skin is essential when simulating deformations occurring in the skin during body movements or clinical procedures. In this study constitutive stress-strain relationships based on experimental data from human skin in vivo were obtained. A series of multiaxial loading experiments were performed on the forearms of four age- and gender matched subjects. The tissue geometry, together with recorded displacements and boundary forces, were combined in an analysis using finite element modelling. A non-linear optimization technique was developed to estimate values for the material parameters of a previously published constitutive law, describing the stress-strain relationship as a non-linear anisotropic membrane. Ten sets of material parameters where estimated from the experiments, showing considerable differences in mechanical behaviour both between individual subjects as well as mirrored body locations on a single subject. The accuracy of applications that simulate large deformations of human skin could be improved by using the parameters found from the in vivo experiments as described in this study.

Loss of skin elasticity precedes to rapid increase of wrinkle levels

BACKGROUND

Decreased skin elasticity is considered as a factor that promotes wrinkle formation. However, the relationship between decreased skin elasticity and the formation of wrinkles is not fully understood.

OBJECTIVE

The purpose of this study is to characterize the relationship between skin elasticity and wrinkle formation using quantitative methods.

METHODS

Skin elasticity at the corner of the eye was measured using a Cutometer SEM575. Wrinkle levels at the corner of the eye were determined from three-dimensional analysis of surface replicas. Ninety healthy female volunteers living in Tokyo, Japan (aged 18-76 years) were examined in this study.

RESULTS

In each scatter plot examined, women with lower U(r)/U(f) values or with higher U(v)/U(e) values showed a tendency for increased R(a) and R(max) values. However, this study determined widely scattered values for both types of parameters. These relationships were then reanalyzed in relation to age. Results were compared within a young (YNG) group of 27 women (aged 18-29), a middle-aged (MED) group of 26 women (aged 30-48) and an elderly (OLD) group of 37 women (aged 50-76). For elasticity parameters, U(r)/U(f) and U(v)/U(e) values, significant differences were found between the YNG and MED groups and also between the MED and OLD groups. For roughness parameters, a significant difference was found only between the MED and OLD groups. These results suggest that changes in R(a) or R(max) values lag about 20 years behind changes in skin elasticity values.

CONCLUSIONS

Despite a strong relationship, elasticity parameters are unlikely to be an independent predictor of wrinkle levels. The amount of UV exposure to skin with decreased elasticity seems to be the variable that determines wrinkle levels. This finding represents another complexity in the mechanism of wrinkle formation.

Effect of room humidity on the formation of fine wrinkles in the facial skin of Japanese

BACKGROUND/PURPOSE

Changes in humidity are commonly known to influence the condition of the skin. Previous studies of the skin dealt with variations in relative humidity (RH) either through statistical analysis or by maintaining room humidity at a constant level; however, the range of humidity and the length of acclimation varied in each study. This study aimed to determine whether the generally used ranges of RH are truly acceptable for studies of human skin.

METHODS

Skin conductance, elasticity and fine wrinkles were assessed on the eyelids of 20 volunteers, first after acclimation for 30 min in a high-humidity room (70% RH) and again after acclimation for 30 min in a low-humidity room (40% RH).

RESULTS

The study found significant decreases in skin conductance and elasticity and significant increases in fine wrinkles after acclimation to low humidity compared with high humidity.

CONCLUSION

These results indicate that even a 30% difference in RH can affect skin properties in 30 min. The importance of humidity stabilization and the necessity of acclimation to the humidity, particularly when the study concerns wrinkles, were thus confirmed.

Effect of Pulse Width of a 595-nm Flashlamp-Pumped Pulsed Dye Laser on the Treatment Response of Keloidal and Hypertrophic Sternotomy Scars

BACKGROUND

Flashlamp-pumped pulsed dye lasers (PDLs) have successfully treated keloidal and hypertrophic scars.

OBJECTIVE

The objective was to investigate the effect of pulse width of a PDL in treating keloidal and hypertrophic scars.

METHODS

On each of 19 patients, keloidal or hypertrophic median sternotomy scars were divided into two segments. Both segments on all patients were randomly treated with a 595-nm PDL at a fluence of 7 J/cm(2) and pulse widths of 0.45 and 40 ms to both segments, every 4 weeks for a total of three treatments. Scar volume, height, erythema, and pliability were measured at Weeks 0, 4, 8, and 24.

RESULTS

The volume of segments treated with 0.45- and 40-ms pulses decreased significantly after two treatments. Segments treated with a 0.45-ms pulse width showed significantly greater improvement than those treated with 40-ms pulses after three treatments. Elasticity of 0.45-ms segments was significantly higher than those of 40-ms segments, following two treatments. Pulse width had no significant effect in improvement of scar erythema.

CONCLUSIONS

A pulse width of 0.45 ms of PDL was more effective in decreasing scar size and improving scar pliability than that of 40 ms. A 595-nm PDL was safe and effective in treatment of hypertrophic scars and keloids in dark-skinned individuals. This study was supported in part by an educational grant from the Dermatological Society of Thailand.

Inhibition of ultraviolet-B-induced wrinkle formation by an elastase-inhibiting herbal extract: implication for the mechanism underlying elastase-associated wrinkles

BACKGROUND

Previously, we have demonstrated that fibroblast-derived elastase plays an essential role in the increased three-dimensional tortuosity of elastic fibers, contributing to the loss of skin elasticity in UV-B-exposed skin. This decrease in skin elasticity is closely associated with the formation of wrinkles induced by UV exposure.

OBJECTIVE

To further clarify the role of elastase in the formation of wrinkles induced by UV exposure, we assessed the effects of an extract of Zingiber officinale (L.) Rose (which inhibits fibroblast-derived elastase) on the wrinkle formation induced by chronic UV-B irradiation.

RESULTS

Topical application of an extract of Zingiber officinale (L.) Rose to rat or hairless mouse skin significantly inhibited the wrinkle formation induced by chronic UV-B irradiation at a suberythemal dose, which was accompanied by a significant prevention of the decrease in skin elasticity in both types of animal skin. In the rat hind limb skin, consistent with the inhibition of reduced skin elasticity, wrinkle prevention occurred concomitantly with a significant decrease in the curling and three-dimensional tortuosity of dermal elastic fibers.

CONCLUSION

Our results indicate that herbal extracts with an ability to inhibit fibroblast-derived elastase may prove to be effective as anti-wrinkling agents, confirming the important role of elastase in UV-B-induced wrinkle formation.

Effect of dermal thickness, tissue composition, and body site on skin biomechanical properties

BACKGROUND/PURPOSE

Quantitative measurement of skin biomechanical properties has been used effectively in the investigation of physiological changes in tissue structure and function and to determine treatment efficacy. As the methods are applied to new questions, tissue characteristics that may influence the resultant biomechanical properties are important considerations in the research design. For certain applications, variables such as dermal thickness and subdermal tissue composition, as well as age and/or solar exposure, may influence the skin biomechanics.

METHODS

We determined the influence of dermal thickness, tissue composition, and age on the skin biomechanical properties at the shoulder, thigh, and calf among 30 healthy females. We compared two devices, the Biomechanical Tissue Characterization System and the Cutometer SEM 575 Skin Elasticity Meter , to determine the effect of tissue sampling size. Dermal thickness was measured with 20 MHz ultrasound (Dermascan C) and tissue composition was inferred from anthropomorphic data.

RESULTS

Skin thickness was significantly correlated with stiffness, energy absorption, and U(r)/U(f) for the shoulder. Body mass index (BMI) was significantly correlated with stiffness (negative correlation), energy absorption (positive), and skin thickness (negative) for the shoulder. Significant differences across body sites were observed. The calf was significantly different from the thigh and shoulders for all parameters (P<0.05, one-way anova). The calf had significantly lower laxity, laxity%, elastic deformation, energy absorption, elasticity, elasticity %, U(r), U(f), and U(r)/U(f) and significantly higher stiffness compared with the thighs and shoulders. sites. The thigh and shoulder sites were significantly different for all parameters except U(r)/U(f), elasticity %, laxity%, and stiffness. The dominant and non-dominant sides were significantly different. The dominant side (right for 90% of the subjects) had increased stiffness and decreased energy absorption (tissue softness, compliance) compared with the left side. A significant (P< or =0.02) negative relationship with age was seen for all biomechanical measures except stiffness at the shoulder. For the thigh and calf sites, significant negative correlations with age were found for elasticity %, U(r), and U(r)/U(f). Age and skin thickness were not correlated in this population. Skin thickness and age influenced the energy absorption at the shoulder site. The biological elasticity at the calf site could be predicted by age and BMI. The biological activity at the thigh site could be predicted by skin thickness and BMI.

CONCLUSIONS

Significant regional variations in biomechanical properties and dominant side effects were observed. The biomechanical properties were significantly influenced by age. Certain properties varied with dermal thickness and tissue composition. The parameters were well correlated between the two instruments. The Cutometer, with its smaller aperture, was found to be more sensitive to age relationships.

Ovariectomy is sufficient to accelerate spontaneous skin ageing and to stimulate ultraviolet irradiation-induced photoageing of murine skin

BACKGROUND

Wrinkling and sagging of the skin during photoageing is physiologically associated with diminished elasticity, which can be attributed to increased fibroblast-derived elastase activity. This degrades the dermal elastic fibres needed to maintain the three-dimensional structure of the skin. We previously reported that ovariectomy accelerates ultraviolet (UV)B-induced wrinkle formation in rat hind limb skin by altering the three-dimensional structure of elastic fibres.

OBJECTIVES

In this study, we used hairless mice to assess the effects of ovariectomy with or without chronic UVA or UVB radiation on sagging and wrinkling of skin, on the elasticity of skin, as well as on matrix metalloproteinase activities in the skin.

METHODS

Ovariectomies or sham operations were performed on 6-week-old female ICR/HR hairless mice.

RESULTS

Even in the ovariectomy group without UV irradiation, the skin elasticity was significantly decreased during the 3-13 weeks after ovariectomy, which was accompanied by a significant increase in elastase activity in the skin. After UVA or UVB irradiation, skin elasticity was significantly decreased to a greater extent in the ovariectomy group than in the sham operation group, and this was accompanied by a reciprocal increase in elastase activity but not in the activities of collagenases I or IV in the skin. Consistent with the decreased skin elasticity, UVA irradiation for 12 weeks elicited more marked sagging in the ovariectomy group than in the sham operation group. UVB irradiation for 12 weeks also induced more marked wrinkle formation in the ovariectomy group than in the sham operation group.

CONCLUSIONS

These results suggest that ovariectomy alone is sufficient to accelerate skin ageing and to increase UV sensitivity, which results in the further deterioration of the skin and photoageing, and may account for the accelerated skin ageing seen in postmenopausal women.

Influence of hydration and experimental length scale on the mechanical response of human skin in vivo, using optical coherence tomography

BACKGROUNDS/AIMS

Human skin is a complex tissue consisting of different layers. To gain better insight into the mechanical behaviour of different skin layers, the mechanical response was studied with experiments of various length scales. Also, the influence of (superficial) hydration on the mechanical response is studied. The work is based on the hypothesis that experiments with different length scales represent the mechanical behaviour of different skin layers. For suction, this means that a large aperture diameter reflects the behaviour of mainly dermis, whereas a very small diameter reflects the behaviour of only the top layer of the skin.

METHODS

Suction measurements at varying pressures and aperture sizes were performed on the volar forearm of 13 subjects aged 29-47 years. The deformation of the skin was visualized using ultrasound (US) (dermis) and optical coherence tomography (OCT) (epidermis and dermis). US measurements were performed on hydrated skin, OCT measurements on dry and hydrated skin. The experiment was simulated by a finite element model (FEM) exhibiting extended Mooney material behaviour. An identification method was used to compare the experimental and numerical results to identify the parameters of the material.

RESULTS

The material parameters C(10) and C(11) were calculated for four subjects: C(10)=29.6+/-21.1 kPa and C(11)=493+/-613 kPa for 6 mm aperture diameter, C(10)=11.5+/-8.7 kPa and C(11)=18.3+/-12.6 kPa for 2 mm aperture diameter and C(10)=10.8+/-9.5 kPa and C(11)=9.3+/-7.7 kPa for 1 mm aperture diameter. Skin hydration caused ambiguous effects on the mechanical response.

CONCLUSIONS

US and OCT, combined with suction, using varying apertures sizes, proved to be a valuable tool to study the mechanical behaviour of different skin layers. With increasing experimental length scale, increasing values for the parameters of the material model were found. This indicates the need of a multi-layered material layer FEM, which can be used to identify mechanical behaviour of epidermis and dermis.

The Effect of Sunscreen on Skin Elastase Activity Induced by Ultraviolet-A Irradiation

It has been reported that application of sunscreens prevents the photoaging of skin in animal models and in humans. We irradiated the dorsal skin of hairless mice with ultraviolet-A (UVA), and investigated the effects of sunscreens on skin elastase activity and on skin properties. Six-week-old female HR/ICR hairless mice were used in these experiments. After being treated with either a UVA sunscreen (also containing ultraviolet-B (UVB) sunscreen to eliminate any slight UVB in the UVA lamps; Protection Factor of UVA (PFA)=6, Sun Protection Factor (SPF)=20) or a vehicle, the dorsal skins of mice were irradiated with the UVA lamps at 22.3 J/cm(2)/d, 5 times a week. At the end of 15 weeks skin properties were evaluated and elastase activities were measured. In the vehicle control group, UVA irradiation increased the brightness and yellowing of the skin, decreased the water content of the stratum corneum, increased skin thickness, decreased skin elasticity, increased skin elastase activity, and decreased the ability of the skin to recover in a pinch test, as compared to an unirradiated group. All these differences were statistically significant. In the UVA sunscreen group, both the UVA induced skin damage and the increase in skin elastase activity were significantly inhibited, as compared to the vehicle group. However, as compared to the unirradiated group, skin elastase activity was significantly increased and immediate extensibility of skin (Ue) was significantly decreased, thereby indicating that the UVA sunscreen did not prevent photoaging to the same level as the unirradiated group. These results suggest the partial efficacy of the topical photoprotection from UVA by the sunscreen in inhibiting elastase activation, and also suggest the possibility of reducing photoaging.

The Use of Pulsed Dye Laser for the Prevention and Treatment of Hypertrophic Scars in Chinese Persons

BACKGROUND

Pulse dye laser has been used with variable degrees of success in the treatment of hypertrophic scars, and although earlier reports suggested a significant degree of improvement, more recent studies have raised concern about its effectiveness. Furthermore, most previous studies examined its use in patients with light skin types, and the use of pulse dye laser in dark-skinned patients for the treatment of hypertrophic scars is not well established.

OBJECTIVE

The objective was to assess the role of pulsed dye laser therapy in the treatment and prevention of hypertrophic scars in Chinese persons.

METHODS

Twenty-nine patients (35 scars) who had scars for less than 6 months were recruited into the prevention group, and 27 patients (36 scars) who had scars for more than 6 months were recruited into the treatment arm of the study. Each received pulse dye laser treatment (585 nm, 1.5-msec pulse duration, 5-mm spot size, 7-8 J/cm(2)) for three to six treatments at 8-week intervals. Half of the scar was treated with the laser and the other half was used as a control. All patients were assessed for subjective improvement with the use of a structured questionnaire and objectively with ultrasonography for thickness and a cutometer for viscoelasticity. Scars were marked on every patient and mapped with a translucent paper at the first appointment to ensure the consistency of location. At the end of the study, 15 patients from the prevention group (15 scars) and 23 patients from the treatment group (34 scars) agreed to return for spectrophotometer assessment.

RESULTS

Fifty-four percent of patients in the prevention group and 66% of patients in the treatment group considered their scars to be better or much better. For both groups of patients, there was significant improvement in term of pruritics after laser treatment. For objective assessment, although scar thickness reduced significantly compared to baseline in the treatment group, such change was not significant when changes in the control side were taken into consideration. There was insignificant change in viscoelasticity. Spectrophometer assessment indicated a significant degree of lightening in the treatment group.

CONCLUSION

Our study indicated that although there was significant symptomatic improvement, there was an insignificant degree of objective improvement in terms of scar thickness and viscoelasticity in the prevention group compared to the control group. Our findings are in line with several previous controlled studies and contradict the results of several others. Such differences can be due to differences in assessment methodology, laser settings, skin type, and scar location. Suprapurpuric pulsed dye laser should not be considered as the standard of practice for the treatment and prevention of hypertrophic surgical scars especially in the chest in Asians patients.

Use of 1,320 nm Nd:YAG laser for wrinkle reduction and the treatment of atrophic acne scarring in Asians

BACKGROUND AND OBJECTIVES

The role of 1,320 Nd:YAG in non-ablative skin rejuvenation in Asians is has not been established. Furthermore, no study has investigated the effectiveness of 1,320 Nd:YAG laser in the treatment of atrophic scarring in Asians. The objective of our study was to investigate the effectiveness of 1,320 Nd:YAG laser in wrinkle reduction and the treatment of atrophic acne scarring in Asians.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-seven female patients were included in the study: seven were treated for acne scarring and the others for wrinkle reduction. A 1,320 nm Nd:YAG laser (Cooltouch II, Roseville, CA) was used to treat both the cheeks and forehead for the patients with wrinkles, and both cheeks only for patients with atrophic acne scarring. All patients received treatment in the post-auricular areas. A spot size of 10 mm was used, and three passes were performed (two pre-cooling and one post-cooling). Patients were treated monthly for 6 months. All patients were subjectively assessed before and after their last treatment sessions using a structured questionnaire, and objectively assessed by the use of clinical photographs for by independent observers. A cutometer was used to assess viscoelasticity, and biopsies were taken at the post-auricular site for assessment by a pathologist.

RESULTS

The overall degree of patients' satisfaction was rated as 4.9 (range 0-9.8) for wrinkle reduction and 4 (range 0-10) for acne scarring. In terms of objective assessment by independent observers, the degree of improvement was considered to be mild or no change in most cases. The independent pathologist who assessed the degree of improvement in terms of increased collagen production detected no change in 8 patients, mild improvement in 9, and moderate improvement in 10. There was also improvement in term of epidermal thickness in 13 cases. Assessment by viscoelasticity indicated a significant degree of improvement in most parameters in both groups of patients. Blistering occurred in five cases, all in the central facial areas, and post-inflammatory hyperpigmentation occurred in three cases. All cases of PIH resolved after the use of 4% hydroquinoine. There was no scarring or hypopigmentation.

CONCLUSIONS

The 1,320 nm Nd:YAG laser is effective for wrinkle reduction and atrophic acne scar improvement, but to further enhance the clinical outcome a combination approach with another device such as IPL and a surgical technique such as subcision is necessary.

Effects of Aging, Menopause, and Hormone Replacement Therapy on Forearm Skin Elasticity in Women

OBJECTIVES

To investigate the decline per year in skin elasticity in postmenopausal women and how much hormone replacement therapy (HRT) increased elasticity over 12 months.

DESIGN

Observational study of convenience sample.

SETTING

The Cardiovascular Hospital of Central Japan, a cardiovascular medical center.

PARTICIPANTS

One hundred seventy-six postmenopausal subjects, mean age+/-standard deviation=61.3+/-9.1.

MEASUREMENTS

In Study 1, skin elasticity was measured in the right forearm using a suction device. Comparisons also were made with 45 premenopausal subjects (aged 34.5+/-9.9). Skin elasticity in the right forearm was measured using the same device at baseline and 12 months after initiation of HRT.

INTERVENTIONS

In Study 2, 12 postmenopausal subjects (mean age=57.1+/-7.4, range 49-71) received conjugated equine estrogen (0.625 mg/d) in combination with medroxyprogesterone acetate (2.5 mg/d) for 12 months.

RESULTS

In Study 1, significant negative correlations between skin elasticity and age and years since menopause were found (r=-0.60, P<.001 for each), as well as a 0.55% decline per year in skin elasticity. In Study 2, 12 months of HRT significantly increased skin elasticity in postmenopausal subjects, by 5.2%.

CONCLUSION

After menopause, skin elasticity declined 0.55% per year; 12 months of HRT increased elasticity by 5.2%.

Effects of aging and postmenopausal hypoestrogenism on skin elasticity and bone mineral density in Japanese women

Skin collagen content and bone mass decrease with aging. Loss of collagen from the skin might decrease its elasticity. We investigated associations between skin elasticity, bone mineral density (BMD), age, and menopausal hypoestrogenism. Thirty-eight healthy Japanese postmenopausal women were studied (mean age, 55.7 +/- 5.9 yr; range, 48 to 71). Skin elasticity was measured using a suction device applied to the dorsal right forearm. BMD values of L2 to 4 vertebral bodies were measured by dual-energy X-ray absorptiometry. Age showed significant negative correlations with both skin elasticity and BMD (r = -0.57, p<0.001 and r = -0.40, p<0.05, respectively). Years since menopause also showed significant negative correlations with both skin elasticity and BMD (r = -0.51, p<0.01 and r = -0.41, p<0.05, respectively). We also found a positive correlation between skin elasticity and BMD in these postmenopausal women (r = 0.44, p<0.01). In conclusion, we demonstrated declining skin elasticity and bone mass in postmenopausal women to possibly be age- and estrogen-related. Additionally, decreased skin elasticity might serve as a predictor of bone loss in postmenopausal women.

Skin elasticity meter or subjective evaluation in scars: a reliability assessment

Various methods are available for evaluating the elasticity of scars. However, the reliability and validity of these methods have been sparsely examined. The aim of this study was to examine the reliability of the subjective evaluation of scar pliability, while at the same time testing the reliability of the measurements of a non-invasive suction device (Cutometer Skin Elasticity Meter 575) on scars. Four observers assessed 49 scar areas of 20 patients with a subjective assessment of pliability. Subsequently, each observer measured the scar areas with the Cutometer. The intraclass correlation coefficients (ICC) of the elasticity (Ue) and extension (Uf) parameters of the Cutometer were acceptable (r = 0.76 and 0.74, respectively) when a single observer carried out the measurements. The subjective assessment of pliability needs to be completed by two or more observers to make the evaluation reliable (r = 0.79). The concurrent validities between the subjective pliability-assessment and each of the Cutometer parameters were statistically significant and ranged from r = 0.29-0.53. The correlations between each of the Cutometer parameters were high and statistically significant (r > or = 0.71).

CONCLUSION

A single observer can reliably use the Cutometer for the elasticity measurements of scars. Furthermore, either Ue or Uf, instead of all five elasticity values provided by the Cutometer, can be adequately used for the elasticity measurements of scars. The subjective assessment of pliability of scars can only be assessed reliably when completed by two or more observers. The concurrent validity showed that all Cutometer parameters, except for visco-elasticity (Uv), and the subjective assessment of pliability measured the same characteristic of a scar.

Involvement of changes in stratum corneum keratin in wrinkle formation by chronic ultraviolet irradiation in hairless mice

Chronic exposure to ultraviolet (UV) radiation alters components of the skin. We previously reported that chronic low-dose UV irradiation induced wrinkle formation but did not significantly alter dermal components of hairless mice. In the present study, we examined whether the epidermal changes by UV irradiation could contribute to wrinkle formation. Hairless mice were irradiated with one-third the minimum erythema dose (MED) of UVB (20 mJ/cm2) and UVA (14 J/cm2) for 10 weeks, and followed up for another 24weeks without irradiation. Fine wrinkles were detected following irradiation, which existed even 24 weeks after cessation of irradiation. An increase in the viscoelastic proportion of the total distension (Uv/Ue) was recognized in irradiated mice, which may be related to wrinkle formation. In the epidermis, an increase in the amount of transepidermal water loss and a decrease in the water content of the stratum corneum were seen after 10 weeks of UV irradiation, neither of which recovered during the 24-week observation period. In addition, there was a significant increase in the amount of stratum corneum keratin after 10 weeks of irradiation, which persisted during the 24-week follow-up. The results of our study suggest that chronic low-dose UV irradiation primarily alters the epidermal rather than the dermal components of the skin. In addition, our results indicate that the increased keratin content of the stratum corneum may be involved in the alteration of the physical properties of the skin. This process could be one of the early events of wrinkle formation.

Prospective study of pulsed dye laser in conjunction with cryogen spray cooling for treatment of port wine stains in Chinese patients

BACKGROUND

Pulsed dye laser (PDL) in conjunction with cryogen spray cooling (CSC) is effective in improving efficacy and safety for treatment of port wine stains (PWSs) in whites. However, for dark-skinned patients such as Chinese, only retrospective studies have been performed.

OBJECTIVES

To compare prospectively clinical efficacy in terms of blanching and acute and long-term adverse effects of PDL alone and PDL-CSC for treatment of PWSs in Chinese patients.

METHODS

Thirty-five Chinese patients (13 males and 22 females) were recruited, and 131 treatments were performed. Half of the test area on the PWS was treated with PDL alone, and the contralateral half was treated with PDL-CSC. The degree of PWS blanching was objectively assessed by spectrophotometer. Skin textural changes were detected by cutometer. All measurements were taken at baseline and before each subsequent laser treatment. Patients were interviewed immediately after treatment and again the following week using a visual analog scale questionnaire to assess the degree of pain and swelling. Occurrence of blisters was noted during each follow-up visit. Patients were evaluated for evidence of long-term adverse effects such as dyspigmentation and scarring after three treatments.

RESULTS

Statistically significant higher fluences were used on the PDL-CSC-treated group. The percentage change in the spectrophotometer a* value was significantly greater using PDL-CSC, indicating that there was more PWS blanching after treatment. There was no significant difference in the incidence of skin textural changes after three treatments with PDL alone or PDL-CSC. The immediate pain scores were significantly higher for PDL alone than with PDL-CSC. Blisters were significantly more common on the area treated using PDL alone than PDL-CSC. The overall incidence of long-term adverse effects was not significantly different between the PDL alone and PDL-CSC treatments. PDL-CSC was also the preferred treatment modality for most patients.

CONCLUSIONS

PDL-CSC was more effective than PDL alone for blanching of PWS in Chinese patients. Moreover, PDL-CSC was better tolerated and resulted in a lower incidence of acute adverse effects such as blistering.

The influence of solid lipid nanoparticles on skin hydration and viscoelasticity--in vivo study

Effects on skin hydration and viscoelasticity are important criteria during the development of novel cosmetic formulations. This study focuses on the in vivo performance of a conventional o/w cream and of the same cream enriched with solid lipid nanoparticles (SLN). Influences on skin hydration and viscoelastic properties were investigated with validated devices (Corneometer and Cutometer). After an application period of 4 weeks, significant changes in skin hydration were detected for both formulations. The SLN-enriched cream was significantly more effective than the conventional cream (+24% for the cream and +31% for the SLN-cream). The viscoelastic parameters UF and UA/UF remained almost unchanged, which is attributed to the young age of the volunteers. At this stage, SLN represent a promising compound for hydrating new cosmetic formulations.