Skin viscoelasticity: physiologic mechanisms, measurement issues, and application to nursing science

Does sensitive skin lie in epidermal barrier impairment or abnormalities? Results from an observational study assessing biophysical parameters

BACKGROUND

The pathophysiology of sensitive skin is largely unknown and no univocal data on the role of the epidermal barrier impairment have been identified. The aim of this study was to assess whether subjects with or without sensitive skin differ for some biophysical skin parameters, which reflect skin barrier integrity or skin hyperactivity.

METHODS

This observational, cross-sectional study included adult volunteers not affected with chronic inflammatory skin diseases who attended the Unit of Dermatology and the Center of Cosmetology of the University of Ferrara, Ferrara, Italy, between March 2021 and November 2022. All subjects, subdivided into those with or without sensitive skin, based on either Lactic Acid Stinging Test (LAST) result or a questionnaire-based skin sensitivity score ≥4, were tested for transepidermal water loss (TEWL), skin elasticity and hydrations and dermographism.

RESULTS

One hundred and eighty-seven subjects were included. No significant differences in terms of TEWL, elasticity and hydration levels were recorded between subjects with sensitive skin and those without, subdivided according to both the LAST result and the questionnaire score. Dermographism was elicited more in subjects with sensitive skin than in the others, although without statistical significance.

CONCLUSIONS

The study failed to find significant biophysical differences between sensitive and non-sensitive skin. Therefore, the role of skin barrier impairment does not appear to be a necessary condition in determining an abnormal skin sensitivity to potentially unpleasant and irritating stimuli. These findings indirectly support the relevance of a peripheral sensory neural hyperactivity in the pathophysiology of sensitive skin.

Guidelines for Manufacturing and Application of Organoids: Skin

To address the limitations of animal testing, scientific research is increasingly focused on developing alternative testing methods. These alternative tests utilize cells or tissues derived from animals or humans for in vitro testing, as well as artificial tissues and organoids. In western countries, animal testing for cosmetics has been banned, leading to the adoption of artificial skin for toxicity evaluation, such as skin corrosion and irritation assessments. Standard guidelines for skin organoid technology becomes necessary to ensure consistent data and evaluation in replacing animal testing with in vitro methods. These guidelines encompass aspects such as cell sourcing, culture techniques, quality requirements and assessment, storage and preservation, and organoid-based assays.

Annurca Apple Oleolite as Functional Ingredient for the Formulation of Cosmetics with Skin-Antiaging Activity

The identification of natural remedies for the management of the skin aging process is an increasingly growing issue. In this context, ursolic acid (UA), a ubiquitous molecule, mainly contained in Annurca apple (AA) fruit, has demonstrated valuable cosmetic potential. To this end, in the current study, the AA oleolite (AAO, extract in sunflower oil containing 784.40 ± 7.579 µg/mL of UA) was evaluated to inhibit porcine elastase enzymatic reactions through a validated spectrophotometric method. AAO has shown a valuable capacity to contrast the elastase enzyme with a calculated IC50 of 212.76 mg/mL, in comparison to UA (IC50 of 135.24 μg/mL) pure molecules and quercetin (IC50 of 72.47 μg/mL) which are used as positive controls. In this context and in view of the valuable antioxidant potential of AAO, its topical formulation with 2.5% (w/w) AAO was tested in a placebo-controlled, double-blind, two-arm clinical study on 40 volunteers. Our results indicated that after 28 days of treatment, a significant reduction of the nasolabial fold (-7.2 vs. baseline T0, p < 0.001) and forehead wrinkles (-5.3 vs. baseline T0, p < 0.001) were registered in combination with a valuable improvement of the viscoelastic skin parameters, where skin pliability/firmness (R0) and gross elasticity (R2) were significantly ameliorated (-13% vs. baseline T0, p < 0.001 for R0 and +12% vs. baseline T0, p < 0.001 for R2). Finally, considering the positive correlation between skin elasticity and hydration, the skin moisture was evaluated through the estimation of Trans epidermal water loss (TEWL) and skin conductance.

Skin properties associated with skin tears in older adults: A case-control study

BACKGROUND

The world population is growing rapidly and skin problems such as skin tears (STs) are more common in aging skin due to changes in the epidermis and dermis. Identification of ageing related skin properties, which are risk factors for STs, is essential for the development of ST prevention protocols.

OBJECTIVE

The aim of this study was to reveal the skin properties related to epidermal function and dermal associated with STs.

MATERIAL AND METHODS

A prospective case-control study was conducted with a sample of 36 older adults, 18 participants with ST and 18 participants without ST, in two elderly care centers. Tewameter TM 210 was used to measure transepidermal water loss, the Sebumeter SM810 was used to measure sebum, and Cutometer Dual MPA 580 was used to measure skin viscoelasticity (R0-R9). The differences of skin properties between groups were analyzed using the independent t-test and Mann-Whitney U test.

RESULTS

The case group had a mean age of 77,17 ± 9,7 and the control group had a mean age of 75,33 ± 6,8. It was determined that there were more ecchymosis (p < 0.000), hematoma (p = 0.008), and ST history (p = 0.001) in the case group. Older adults in the case group were more frail than the control group (p = 0.044). Regarding the score of the skin properties, the case group showed that the TEWL levels of the older adults in the case group were lower (p = 0.031) compared to the control groups. There was a significant difference between the groups and R0, R2, R5, and R7. While R0 was higher in the case group, R2, R5, and R7 were lower than the control group.

CONCLUSION

Older adults with ST showed differences in skin properties compared to those without ST, especially transepidermal water loss, and viscoelasticity (R0, R2, R5, R7). The results of this study suggest that some changes in skin properties may be a risk factor for STs.

A randomized, double-blind, controlled study evaluating the effects of two facial serums on skin aging

BACKGROUND

Skin aging is a natural process that occurs because of oxidative stress. Facial skin aging is often concerning for individuals due to the exposure of the face.

OBJECTIVES

To assess and compare the effects of two anti-aging facial serums on the following characteristics associated with facial skin aging: fine lines/wrinkles, age spots, firmness, elasticity, texture, radiance, tone, lifting, clarity, and complexion.

METHODS

A 24-week, double-blind controlled study was conducted on 130 participants who were randomized into two groups: facial serum with Liposomal Blend and facial serum without Liposomal Blend. Clinical evaluations (Visual Analog Scale) and instrumental evaluations (Cutometer, SIAscope, and Clarity Pro image analysis) were performed at weeks 0 (baseline), 2, 4, 8, 12, and 24 to assess for changes in skin aging characteristics.

RESULTS

A total of 123 participants completed the study; participants that used the facial serum with Liposomal Blend had significantly greater improvements in skin aging characteristics compared to those that used the facial serum without Liposomal Blend. This study shows that Liposomal Blend is a vehicle with the ability to enhance the anti-aging properties of the ingredients within the facial serum by facilitating its delivery into the underlying layers of the skin. Higher concentration of ingredients at the site of action could potentially lead to greater damage repair and improvements in signs of facial skin aging.

CONCLUSION

By using Liposomal Blend, practitioners and pharmacists could potentially improve the delivery of the ingredients within their formulations into the skin, which may lead to increased treatment efficacy.

Viscoelasticity of Liposomal Dispersions

Janus-faced viscoelastic gelling agents-possessing both elastic and viscous characteristics-provide materials with unique features including strengthening ability under stress and a liquid-like character with lower viscosities under relaxed conditions. The mentioned multifunctional character is manifested in several body fluids such as human tears, synovial liquids, skin tissues and mucins, endowing the fluids with a special physical resistance property that can be analyzed by dynamic oscillatory rheology. Therefore, during the development of pharmaceutical or cosmetical formulations-with the intention of mimicking the physiological conditions-rheological studies on viscoelasticity are strongly recommended and the selection of viscoelastic preparations is highlighted. In our study, we aimed to determine the viscoelasticity of various liposomal dispersions. We intended to evaluate the impact of lipid concentration, the presence of cholesterol or 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and the gelling agents polyvinyl alcohol (PVA) and hydroxyethylcellulose (HEC) on the viscoelasticity of vesicular systems. Furthermore, the effect of two model drugs (phenyl salicylate and caffeine) on the viscoelastic behavior of liposomal systems was studied. Based on our measurements, the oscillation rheological properties of the liposomal formulations were influenced both by the composition and the lamellarity/size of the lipid vesicles.

Rheological Considerations of Pharmaceutical Formulations: Focus on Viscoelasticity

Controlling rheological properties offers the opportunity to gain insight into the physical characteristics, structure, stability and drug release rate of formulations. To better understand the physical properties of hydrogels, not only rotational but also oscillatory experiments should be performed. Viscoelastic properties, including elastic and viscous properties, are measured using oscillatory rheology. The gel strength and elasticity of hydrogels are of great importance for pharmaceutical development as the application of viscoelastic preparations has considerably expanded in recent decades. Viscosupplementation, ophthalmic surgery and tissue engineering are just a few examples from the wide range of possible applications of viscoelastic hydrogels. Hyaluronic acid, alginate, gellan gum, pectin and chitosan are remarkable representatives of gelling agents that attract great attention applied in biomedical fields. This review provides a brief summary of rheological properties, highlighting the viscoelasticity of hydrogels with great potential in biomedicine.

Fabrication of polyvinyl pyrrolidone-K90/Eudragit RL100-based dissolving microneedle patches loaded with alpha-arbutin and resveratrol for skin depigmentation

Alpha-arbutin (AA) and resveratrol (Res) are widely used in skin-lightening products. However, current topical formulations have minimal skin-lightening effects due to the low absorption and poor solubility of these active compounds. This study investigated the efficacy and safety of using dissolving microneedle (DMN) patches to improve the delivery of AA and Res for skin depigmentation. The DMN patches (F0-F3) fabricated from polyvinyl pyrrolidone-K90 (PVP-K90)/Eudragit RL100 blends successfully penetrated excised porcine skin and showed sufficient mechanical strength to resist compression forces. Loading DMNs with 10% AA and 2% Res at a ratio of 5 : 1 (F3) resulted in a synergistic interaction between the drugs with desirable dissolving ability, drug loading, and stability. Furthermore, both in vitro and in vivo studies revealed that the use of F3 DMN patches successfully enhanced the intradermal delivery of AA and Res over a 24 h period, with the delivered amount being higher (∼2.6 times) than that provided by a cream formulation (P < 0.05). After removing the DMN patches, the mice's skin was spontaneously and completely resealed within 12 h. In clinical studies, F3 DMN patches slightly decreased the melanin index of the participants without causing skin irritation or erythema at any time during the 24 h period when the patches were applied (P < 0.05). Moreover, application of the patches for 24 h was not found to affect skin hydration, transepidermal water loss, or skin elasticity. Therefore, AA/Res-loaded DMN patches could offer a promising approach for the effective local delivery of cosmetic agents for skin depigmentation.

Is "Initial Size of the Graft the Real Culprit behind Primary Contraction of Full-Thickness Skin Graft"? - A Cross-Sectional Study

Background  Primary contraction of full-thickness graft has been traditionally quoted to be 40%. There are lacunae in literature to elaborate on the factors influencing it ever since. Methods  About 75 subjects who underwent full-thickness grafting procedures to resurface small defects were included in the study. The initial and final graft dimensions after primary contraction were traced on X-ray templates and the percentage of contraction was evaluated using the graphical method. This was further correlated with age, collagen, elastic matrix metalloproteinases-1 (MMP-1) and -2 content along with dermal thickness of the skin specimen sent from the graft. Results  The primary contraction of the graft had a very significant correlation only with the initial size of graft harvested with a linear regression of 33.3% and a Spearman's correlation of 0.587 significant at a p -value of 0.001. Conclusion  This study though preliminary tries to highlight an important factor that primary contraction of grafts is a physical phenomenon independent of its contents like collagen, elastin, or MMP-1 and -2 or age and dependent on its initial size of harvest instead.

Soap or alcohol-based products? The effect of hand hygiene on skin characteristics during the COVID-19 pandemic

BACKGROUND

Different strategies for hand skin hygiene have been used to prevent the spread of SARS-CoV-2. However, frequent hand sanitization has been associated with skin damage. The present study aimed to evaluate hand hygiene habits during the COVID-19 pandemic and the effect of the repetitive use of soap or alcohol-based products on skin characteristics.

METHODS

We conducted a survey regards hand hygiene habits acquired during the COVID-19 pandemic. Also, we performed cutometry in a cohort of individuals who cleansed their volar forearms every 30 min, during 4 h, using soap or alcohol-based products.

RESULTS

We received 138 responses from people with medium-high educational level who reported a 2.5-time increase in the frequency of hand cleansing (p < 0.0001) that resulted in skin damage. An in vivo analysis of skin moisture and elasticity was also performed among 19 health workers and students. In general, skin moisture decreased with every cleansing, mainly after 2 h of washing with soap (p < 0.01), while skin elasticity only reduced after 4 h of treatment (p < 0.05). Alcohol-based solution or alcohol-based gel (70% ethanol, both) did not affect skin moisture or elasticity during testing.

CONCLUSION

It is known that the excessive use of soap or alcohol-based products causes dermatological issues. The present study demonstrates that non-medicated soap significantly affects skin moisture and elasticity, probably because the soap removes the hydrolipidic protective barrier, favoring transepidermal water loss, where the lack of the appropriate stratum corneum hydration also affects skin elasticity, mainly associated with changes in epidermal structure.

Viscoelastic properties of plasma-agarose hydrogels dictate favorable fibroblast responses for skin tissue engineering applications

Dermal wound healing relies on the properties of the extracellular matrix (ECM). Thus, hydrogels that replicate skin ECM have reached clinical application. After a dermal injury, a transient, biodegradable fibrin clot is instrumental in wound healing. Human plasma, and its main constituent, fibrin would make a suitable biomaterial for improving wound healing and processed as hydrogels albeit with limited mechanical strength. To overcome this, plasma-agarose (PA) composite hydrogels have been developed and used to prepare diverse bioengineered tissues. To date, little is known about the influence of variable agarose concentrations on the viscoelastic properties of PA hydrogels and their correlation to cell biology. This study reports the characterization of the viscoelastic properties of different concentrations of agarose in PA hydrogels: 0 %, 0.5 %, 1 %, 1.5 %, and 2 % (w/v), and their influence on the cell number and mitochondrial activity of human dermal fibroblasts. Results show that agarose addition increased the stiffness, relaxation time constants 1 (τ1) and 2 (τ2), and fiber diameter, whereas the porosity decreased. Changes in cell metabolism occurred at the early stages of culturing and correlated to the displacement of fast (τ1) and intermediate (τ2) Maxwell elements. Fibroblasts seeded in low PA concentrations spread faster during 14 d than cells cultured in higher agarose concentrations. Collectively, these results confirm that PA viscoelasticity and hydrogel architecture strongly influenced cell behavior. Therefore, viscoelasticity is a key parameter in the design of PA-based implants.

Standardizing Dimensionless Cutometer Parameters to Determine In Vivo Elasticity of Human Skin

Objective: Skin fibrosis places an enormous burden on patients and society, but disagreement exists over methods to quantify severity of skin scarring. A suction cutometer measures skin elasticity in vivo, but it has not been widely adopted because of inconsistency in data produced. We investigated variability of several dimensionless parameters generated by the cutometer to improve their precision and accuracy. Approach: Twenty adult human subjects underwent suction cutometer measurement of normal skin (NS) and fibrotic scars (FS). Using Mode 1, each subject underwent five trials with each trial containing four curves. R0/2/5/6/7 and Q1/2/3 data were collected. Analyses were performed on these calculated parameters. Results: R0/2/5/6/7 and Q1/2 parameters from curves 1 to 4 demonstrated significant differences, whereas these same parameters were not significantly different when only using curves 2-4. Individual analysis of all parameters between curve 1 and every subsequent curve was statistically significant for R0, R2, R5, R6, R7, Q1, and Q2. No differences were appreciated for parameter Q3. Comparison between NS and FS were significantly different for parameters R5, Q1, and Q3. Innovation: Our study is the first demonstration of accurate comparison between NS and FS using the dimensionless parameters of a suction cutometer. Conclusions: Measured parameters from the first curve of each trial were significantly different from subsequent curves for both NS and FS. Precision and reproducibility of data from dimensionless parameters can therefore be improved by removing the first curve. R5, Q1, and Q3 parameters differentiated NS as more elastic than FS.

Split thickness skin graft versus application of the temporary skin substitute suprathel in the treatment of deep dermal hand burns: a retrospective cohort study of scar elasticity and perfusion

Two therapeutic options for deep dermal hand burns are autologous split-thickness skin graft (STSG) following tangential excision and the application of the temporary wound dressing Suprathel following removal of burn blisters. We compared elasticity and perfusion of burn scars after both types of therapy at least one year after completion of treatment. A case series of 80 patients of our department with deep dermal hand burns between 2013 and 2018 was examined in the year 2019 at least one year after completion of treatment (24 females and 56 males with a median age of 47.6 years). The clinical assessment of the scar was performed with the Vancouver Scar Scale (VSS) and Patient and Observer Scar Assessment Scale (POSAS) and the objective assessment with suction cutometry (MPA 580) and an O2C device on both hands. Our statistical analysis showed no statistically significant differences for the R2 and R5 elasticity values between the two types of therapy. The 95% confidence intervals for the ratios of elasticity, and microcirculatory perfusion parameters and scar scale scores of burn scars to respective healthy areas of skin after STSG and Suprathel-therapy mostly covered 1. Subgroup analysis of R2 viscoelasticity and analyses with adjustments for scar compression therapy, nicotine consumption, age, palmar or dorsal localization of the burn scar and interactions of age with smoking and localization gave similar results. The adjusted analysis of SO2 showed statistically significant lower SO2 values, 9% less, after STSG compared to Suprathel treatment. Split-thickness skin graft following tangential excision and the application of Suprathel following removal of burn blisters may be equivalent options for treatment of deep dermal hand burns. To detect possible small differences, further studies with larger samples are required.

Spermidine-induced recovery of human dermal structure and barrier function by skin microbiome

An unbalanced microbial ecosystem on the human skin is closely related to skin diseases and has been associated with inflammation and immune responses. However, little is known about the role of the skin microbiome on skin aging. Here, we report that the Streptococcus species improved the skin structure and barrier function, thereby contributing to anti-aging. Metagenomic analyses showed the abundance of Streptococcus in younger individuals or those having more elastic skin. Particularly, we isolated Streptococcus pneumoniae, Streptococcus infantis, and Streptococcus thermophilus from face of young individuals. Treatment with secretions of S. pneumoniae and S. infantis induced the expression of genes associated with the formation of skin structure and the skin barrier function in human skin cells. The application of culture supernatant including Streptococcal secretions on human skin showed marked improvements on skin phenotypes such as elasticity, hydration, and desquamation. Gene Ontology analysis revealed overlaps in spermidine biosynthetic and glycogen biosynthetic processes. Streptococcus-secreted spermidine contributed to the recovery of skin structure and barrier function through the upregulation of collagen and lipid synthesis in aged cells. Overall, our data suggest the role of skin microbiome into anti-aging and clinical applications.

Scarring at Donor Sites after Split-Thickness Skin Graft: A Prospective, Longitudinal, Randomized Trial

OBJECTIVE

To investigate if previous findings on the association between dressing treatments and subjective opinion on final donor site scar outcome using the Patient and Observer Scar Assessment Scale (POSAS) can be confirmed objectively. The previous study showed that patients dressed with hydrofiber covered with film were more satisfied with their donor site scars than patients receiving porcine xenograft or polyurethane foam dressings.

METHODS

Scar outcome measurements were assessed by a blinded observer using POSAS and the Cutometer dual MPA 580 device to measure the viscoelasticity of skin.

RESULTS

A total of 17 participants were included in this study, five of whom were treated with hydrofiber, six with polyurethane foam, and another six with porcine xenograft. There were no significant differences among groups in any of the POSAS items or in the viscoelasticity measurements made with the Cutometer.

CONCLUSIONS

The investigators could not confirm previous associations between dressing treatment and long-term donor site scars. No associations between donor sites' healing times and final scarring were found. Hypopigmentation was reported in 15 of 17 donor sites evaluated.

Self-perceived and objective measurements of facial puffiness in Chinese women

BACKGROUND

Facial puffiness, caused by mild or normal fluid retention, commonly experienced by women, may not pose a health risk, but it can be a cause of cosmetic concern. The objectives of this study were to determine whether self-perceived facial puffiness can be measured objectively.

MATERIALS AND METHODS

A total of 151 Chinese women between 20 and 68 years of age were recruited. Facial water content, skin thickness, and elasticity were measured at two time points within a day (visit one occurred when the participants perceived they had facial puffiness; visit two occurred when the participants perceived their facial puffiness had subsided). Participants were also given a rating scale to self-evaluate their puffiness and firmness at different regions of the face.

RESULTS

The participants could perceive a difference in facial puffiness between the two visits. Water content and skin thickness were significantly higher in all regions of the face for all participants during the first visit. Skin elasticity was also significantly different between visits one and two. There was a significant increase in water content and skin thickness in the lower eyelid region in women who were older than 40 years.

CONCLUSION

This is the first study to show that self-perceived facial puffiness can be measured objectively and that skin elasticity can change significantly when facial puffiness subsides.

Effects of low-dose Aloe sterol supplementation on skin moisture, collagen score and objective or subjective symptoms: 12-week, double-blind, randomized controlled trial

Daily oral intake of 40 μg Aloe sterol was shown in a double‐blind clinical trial to significantly increase skin barrier function, moisture and elasticity. Ultrasonographic results also suggested that the intake of Aloe sterol increases collagen content in the dermis. Here, we evaluate the effects of a much smaller dose of Aloe sterol, approximately half that used previously, on skin functions in more detail. This is a monocentric, double‐blind, randomized, placebo‐controlled, supplementation study of the effects of low‐dose Aloe sterol on skin transepidermal water loss, hydration, collagen score, evaluation of objective or subjective symptoms, and safety after 12 weeks of daily intake. We randomly administrated either Aloe sterol or placebo to 122 healthy volunteers. Transepidermal water loss was significantly reduced and collagen score was increased in the Aloe sterol group compared with the placebo group at week 12. In the Aloe sterol group, there was significant improvement of objective skin condition (face erythema and pruritus of inner and outer arms) at week 12 compared with week 0, but not in the placebo group. Subjectively, there was significant improvement of visual analog scale of skin acne, fingernail brittleness and constipation in the Aloe sterol group. According to subgroup analysis, although not planned before the study initiation, subjects with dry skin in the Aloe sterol group had significantly increased skin hydration values at week 12 compared with the placebo group. Our results confirmed that even low‐dose Aloe sterol ingestion improves skin moisture by promoting skin barrier function and dermal collagen production, which contributes to maintenance of healthy skin.

A blackberry-dill extract combination synergistically increases skin elasticity

BACKGROUND

The loss of structural elastin due to intrinsic and extrinsic ageing results in the skin's inability to stretch and recoil (decrease in elasticity) and manifests as loss of skin firmness and sagging. While other extracellular matrix (ECM) components such as collagen and hyaluronic acid are continually synthesized and assembled through life, elastic fibres are not. Elastic fibre assembly and functionality require fibre cross-linking, induced by the lysyl oxidase-like (LOXL) enzymes, which sharply decrease during ageing.

OBJECTIVE

To evaluate the enhanced elastogenic effect of a blackberry-dill extract combination, which was hypothesized to induce elastin fibre component synthesis, fibre cross-linking and reduce elastin fibre degradation.

METHODS

The blackberry and the dill extracts were tested separately and in combination to confirm single ingredient bioactivity and synergistic benefits. Human skin explants, dermal fibroblasts, elastase assays, ELISAs, quantitative real-time PCRs and spectrofluorometer measurements were used. Moreover, a double-blinded, placebo-controlled clinical study was carried out to assess skin elasticity using Cutometer and histologically from biopsies.

RESULTS

The blackberry extract induced elastin gene expression, elastin promoter activity and inhibited elastic fibre degradation by matrix metalloproteinases (MMPs) 9 and 12. The dill extract induced elastin, collagen and LOXL1 gene expression, resulting in enhanced fibre cross-linking in human skin explants. Clinically, the blackberry and dill combination treatment displayed synergistic pro-elasticity activity as compared to each ingredient alone and placebo.

CONCLUSION

Taken together, these results demonstrated the two multimodal plant-based extracts complemented each other in terms of bioactivity and resulted in a synergistic elastogenesis induction.

Fabrication of Aligned Biomimetic Gellan Gum-Chitosan Microstructures through 3D Printed Microfluidic Channels and Multiple In Situ Cross-Linking Mechanisms

In this study we use a combination of ionic- and photo-cross-linking to develop a fabrication method for producing biocompatible microstructures using a methacrylated gellan gum (a polyanion) and chitosan (a polycation) in addition to lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) as the photoinitiator. This work involves the development of a low-cost, portable 3D bioprinter and a customized extrusion mechanism for controlled introduction of the materials through a 3D printed microfluidic nozzle, before being cross-linked in situ to form robust microstructure bundles. The formed microstructures yielded a diameter of less than 1 μm and a tensile strength range of ∼1 MPa. This study is the first to explore and achieve GGMA:CHT microstructure fabrication by means of controlled in-line compaction and photo-cross-linking through 3D printed microfluidic channels.

Efficacy of a collagen hydrolysate and antioxidants-containing nutraceutical on metrics of skin health in Indian women

BACKGROUND

The skin's aging process involves a decreased biosynthesis of extracellular matrix proteins (predominantly collagen) compounded by damage from environmental and intrinsic stressors. The Indian population is susceptible to skin damage given its geography and increasing urbanization or a genetic disposition. Previous studies have investigated nutrients such as collagen peptides, vitamins and phytonutrient-rich botanical extracts for their individual benefits on skin.

AIMS

This study examined the collective effect of a proprietary blend of these nutrients (in Nutrova Collagen+Antioxidants; NCA) on skin parameters, which has not been previously studied, especially in an Indian context.

PATIENTS/METHODS

34 healthy, Indian women (mean age = 39.5 years) were given a placebo daily for 30 days to establish a baseline, followed by NCA for two intervals of 30 days. 3D image reconstruction allowed the analysis of skin topography and blemishes. Instrumental measurements also included skin firmness, elasticity, hydration, and transepidermal water loss. Clinical evaluation was used to grade blemishes, wrinkles and periorbital hyperpigmentation.

RESULTS

Based on instrumental evaluation, NCA significantly reduced wrinkle width, open pores, skin roughness, and the colour of hyperpigmented blemishes, while improving skin hydration, firmness and barrier function from baseline to Day 30 and Day 60. NCA also increased elasticity at Day 30. Clinical evaluation showed that periorbital hyperpigmentation and wrinkles reduced significantly.

CONCLUSION

NCA is effective for improving overall skin health in Indian women. These results show that targeted nutrient supplementation can improve skin health and further research over extended durations is merited.

Understanding rates of genital-anal injury: Role of skin color and skin biomechanics

PURPOSE

A series of studies suggest that non-Hispanic White women have significantly more injuries than non-Hispanic Black women after sexual assault and consensual sexual intercourse. One explanation for this difference is that the degree of skin protection may vary as skin mechanics and skin pigmentation vary. The aim of the study was to determine the association among genital-anal injury, skin color, skin viscoelasticity and skin hydration in women following consensual sexual intercourse when controlling for age, smoking history, body mass index (BMI), sun exposure, and health status.

PROCEDURES

We employed a prospective cohort study design to enroll women 21 years of age or older at two study sites. They underwent two data collection sessions, baseline and follow-up after consensual sexual intercourse. Baseline genital-anal injury identification occurred with a standard forensic examination (direct visualization, nuclear staining with toluidine blue contrast, and colposcopy examination) and measurements of other variables (skin color, skin viscoelasticity, skin hydration, age, smoking history, body mass index [BMI], sun exposure, and health status). Participants were then asked to have consensual sexual intercourse with a male partner of their choice and to return for a second forensic examination for injury detection. Genital-anal injury was regressed on skin color, skin viscoelasticity, skin hydration, age, smoking history, BMI, sun exposure, and health status.

FINDINGS

We enrolled 341 participants, 88 non-Hispanic White (25.8%), 54 non-Hispanic Black (15.8%), 190 Hispanic/Latina (55.7), and 9 Other Identities (2.6%). At baseline the genital-anal injury prevalence was 57.77% and at follow-up after consensual sexual intercourse, injury prevalence was 72.73%. External genital injury prevalence was associated with increased L* (lightness) values (Adjusted Odds Ratio [AOR] = 1.98, 95% Confidence Interval [CI] = 1.03, 4.04) and decreased skin elasticity (AOR = 0.96, 95% CI = 0.93, 0.99) at baseline. Increased skin hydration was associated with a significantly higher frequency of external, internal, anal, and total genital-anal injuries (Adjusted Rate Ratio [ARR] > 1.27) at follow-up. Also at the follow-up examination, Hispanic/Latina participants had significantly lower external genital and total genital-anal injury prevalence and frequency as compared to non-Hispanic White participants (AOR < 0.40).

CONCLUSIONS

Our findings provide qualified support for the importance of skin color during the forensic examination. Women with lighter skin tones may have skin that is more easily injured than women with darker tones. In contrast, external genital injuries may be more easily identified in women with light as compared to dark skin, a situation that is important in both the health care and criminal justice systems. Additionally, women with decreased viscoelasticity and increased hydration may be more easily injured. These findings support the need to develop forensic procedures that are effective in people across the range of skin colors and to interpret forensic findings considering the innate properties of the skin.

The validity and reliability of using ultrasound elastography to measure cutaneous stiffness, a systematic review

BACKGROUND

Ultrasound elastography is an imaging technology which can objectively and non-invasively assess tissue stiffness. It is emerging as a useful marker for disease diagnosis, progression and treatment efficacy.

OBJECTIVE

To examine current, published research evaluating the use of ultrasound elastography for the measurement of cutaneous or subcutaneous stiffness and to determine the level of validity and reliability, recommended methodologies and limitations.

METHODS

MEDLINE, Web of science and Scopus were systematically searched in August 2016 to identify original articles evaluating the use of ultrasound elastography to assess cutaneous stiffness. Relevant studies were then quality evaluated using the Quality Assessment of Diagnostic Accuracy Studies v 2 (QUADAS-2) tool and the Quality Appraisal of Reliability Studies (QAREL).

RESULTS

From a total of 688 articles, 14 met the inclusion criteria for full review. Within the 14 studies, elastography was used to evaluate tumors, systemic sclerosis, lymphedema, abscess, and post-radiation neck fibrosis. Only three robust studies demonstrated good interrater reliability, whereas all validity studies had low sample sizes and demonstrated risks of bias.

CONCLUSION

Robust evidence supporting the use of ultrasound elastography as a diagnostic tool in cutaneous conditions is low, however, initial indicators support further research to establish the utility of ultrasound elastography in dermatology.

Dermal anchoring structures: convex matrix structures at the bottom of the dermal layer that contribute to the maintenance of facial skin morphology

BACKGROUND/PURPOSE

Facial skin must be linked to underlying structures to maintain facial morphology and prevent sagging, but the mechanism of facial skin retention is largely unknown. We aimed to elucidate this mechanism.

METHODS

Twenty-two cheek skin specimens (age range: 10s-60s, both genders) were observed histologically. And 30 cheek of healthy Japanese volunteers (age range: 30s-50s, female) was photographed and the severity of sagging was graded. Dermal layer morphology was observed non-invasively with ultrasound. Skin-retaining force was measured with a Cutometer MPA 580(®) , and sagging severity was evaluated by grading criteria.

RESULTS

Histological observation revealed characteristic convex structures at the bottom of the dermal layer. Non-invasive study showed that the depth of the convex structures, measured by ultrasonography, was significantly negatively related to the ratio of viscoelastic to elastic distention (Uv/Ue) and positively related to the ratio of elastic recovery to total deformation (Ur/Uf) at the cheek of female volunteers, measured by cutometer. It was also negatively related to sagging severity. Further, Ur/Uf was negatively and Uv/Ue was positively related to sagging severity.

CONCLUSION

Characteristic convex structures at the bottom of the dermal layer serve as anchoring structures to maintain skin morphology.

Accuracy Improvement on the Measurement of Human-Joint Angles

A measurement technique that decreases the root mean square error (RMSE) of measurements of human-joint angles using a personal wireless sensor network is reported. Its operation is based on virtual rotations of wireless sensors worn by the user, and it focuses on the arm, whose position is measured on 5 degree of freedom (DOF). The wireless sensors use inertial magnetic units that measure the alignment of the arm with the earth's gravity and magnetic fields. Due to the biomechanical properties of human tissue (e.g., skin's elasticity), the sensors' orientation is shifted, and this shift affects the accuracy of measurements. In the proposed technique, the change of orientation is first modeled from linear regressions of data collected from 15 participants at different arm positions. Then, out of eight body indices measured with dual-energy X-ray absorptiometry, the percentage of body fat is found to have the greatest correlation with the rate of change in sensors' orientation. This finding enables us to estimate the change in sensors' orientation from the user's body fat percentage. Finally, an algorithm virtually rotates the sensors using quaternion theory with the objective of reducing the error. The proposed technique is validated with experiments on five different participants. In the DOF, whose error decreased the most, the RMSE decreased from 2.20(°) to 0.87(°). This is an improvement of 60%, and in the DOF whose error decreased the least, the RMSE decreased from 1.64(°) to 1.37(°). This is an improvement of 16%. On an average, the RMSE improved by 44%.