Ultraviolet Light Causes Skin Cell Senescence: From Mechanism to Prevention Principle.

The skin is an effective protective barrier that significantly protects the body from damage caused by external environmental factors. Furthermore, skin condition significantly affects external beauty. In today's era, which is of material and spiritual prosperity, there is growing attention on skincare and wellness. Ultraviolet radiation is one of the most common external factors that lead to conditions like sunburn, skin cancer, and skin aging. In this review, several mechanisms of UV-induced skin cell senescence are discussed, including DNA damage, oxidative stress, inflammatory response, and mitochondrial dysfunction, which have their own characteristics and mutual effects. As an illustration, mitochondrial dysfunction triggers electron evasion and the generation of more reactive oxygen species, leading to oxidative stress and the activation of the NLRP3 inflammasome, which in turn causes mitochondrial DNA (mt DNA) damage. Based on the current mechanism, suitable prevention and treatment strategies are proposed from sunscreen, dietary, and experimental medications respectively, aimed at slowing down skin cell aging and providing protection from ultraviolet radiation. The effects of ultraviolet rays on skin is summarized, offering insights and directions for future studies on mechanism of skin cell senescence, with an anticipation of discovering more effective prevention and cure methods.

Comparative in vitro activity of Delafloxacin and other antimicrobials against isolates from patients with acute bacterial skin, skin-structure infection and osteomyelitis.

The aim of this study was to compare the in vitro activity of delafloxacin with other fluoroquinolones against bacterial pathogens recovered from inpatients with osteomyelitis, Acute Bacterial Skin and Skin-Structure Infections (ABSSSI). In total, 100 bacterial isolates (58 % Gram-negative and 42 % Gram-positive) recovered from inpatients between January and April 2021, were reidentified at species level by MALDI-TOF MS. Antimicrobial susceptibility testing was conducted using the broth microdilution method and the detection of biofilm formation was assessed through the microtiter plate assay. The screening for mecA was carried out by PCR, while mutations in the Quinolone Resistance Determining Regions (QRDR), specifically gyrA and parC, were analyzed using PCR followed by Sanger sequencing. Results showed that delafloxacin exhibited greater in vitro potency (at least 64-times) than the other tested fluoroquinolones (levofloxacin and ciprofloxacin) when evaluating Staphylococcus aureus (MIC50 ≤0.008 mg/L) and coagulase-negative Staphylococcus (MIC50 0.06 mg/L). Furthermore, delafloxacin (MIC50 0.25 mg/L) was at least 4 times more potent than other tested fluoroquinolones (MIC50 1 mg/L) against P. aeruginosa. No difference in delafloxacin activity (MIC50 0.03 mg/L) was observed against Enterobacter cloacae when compared with ciprofloxacin (MIC50 0.03 mg/L). Despite presenting low activity against K. pneumoniae isolates (22.2 %), delafloxacin exhibited twice the activity compared to both levofloxacin and ciprofloxacin. Delafloxacin also exhibited a strong activity (71.4 %‒85.7 %.) against biofilm producing bacterial pathogens tested in this study. Interestingly, 82.14 % of the staphylococci tested in this study harbored mecA gene. In addition, the gyrA and parC genes in fluoroquinolone-resistant Gram-negative isolates displayed different mutations (substitutions and deletions). Herein, we showed that delafloxacin was the most active fluoroquinolone against staphylococci (including MRSA) and P. aeruginosa when compared to other fluoroquinolones such as ciprofloxacin and levofloxacin.

Noninvasive Detection of the Skin Structure and Inversed Retrieval of Chromophore Information Based on Diffuse Reflectance Spectroscopy.

The detection of skin's structure lays the foundation for personalized laser surgery of vascular skin disease, which can be noninvasively achieved by diffuse reflectance spectroscopy (DRS). A two-step inverse Monte Carlo radiation method based on DRS under two source-detector separations was proposed to quantify the skin structure, including chromophore concentration (melanin fm and hemoglobin fb), epidermal thickness tepi, average vessel diameter Dves, depth dpws and thickness tpws of the vascular layer for diseased skin. The method fitted the simulated DRS to the measured DRS iteratively, differences between which were described by a specific objective function to amplify blood absorption at 500-600 nm, and Dves, dpws, and tpws were estimated based on fm, fb, and tpws fitted in the first step. The results showed that the two-step method dramatically improve the inversion accuracy with mean errors of fm, fb, tpws, and dpws less than 5%.

Morphological characterization of two dermal and hypodermal alterations in an adult man: surgical scar vs. stretch mark.

Scars and stretch marks are extremely common. For scars, evidence of alterations of the dermal and hypodermic layers is known, while for stretch marks, less data are available, and they are considered purely aesthetic conditions. The intra- and inter-subject variability of the skin makes the comparison between these two particularly complex. This study presents the case of a 54-year-old man who had both stretch marks and a surgical scar on his abdomen. We performed ultrasound and elastosonographic investigations for both to analyse the structural alteration of the skin and subcutaneous layers. Their structures were also compared to the structure of intact skin. The two skin conditions appeared substantially morphologically different and different from intact skin. The alterations detected, particularly of the connective structures, allow us to state that both scars and stretch marks are alterations of both the dermis and the hypodermis and stretch marks differ from scars.

Clinical consequences of age-related skin barrier dysfunction. Part I. Structural, molecular and physiologic changes with cutaneous aging.

Aging is associated with significant changes to skin structure and function. As the United States population ages, dermatologists are increasingly presented with the clinical consequences of these changes. Understanding the biology of aging skin allows dermatologists to best guide patients towards proactive treatment of age-related skin disease. The first article of this 2-part continuing medical education series reviews the structural, molecular and functional changes associated with skin aging.

Laser Interference Additive Manufacturing: Mask Bundle Shape Bionic Shark Skin Structure.

Here, we explored a new manufacturing strategy that uses the mask laser interference additive manufacturing (MLIAM) technique, which combines the respective strengths of laser interference lithography and mask lithography to efficiently fabricate across-scales three-dimensional bionic shark skin structures with superhydrophobicity and adhesive reduction. The phenomena and mechanisms of the MLIAM curing process were revealed and analyzed, showing the feasibility and flexibility. In terms of structural performance, the adhesive force on the surface can be tuned based on the growth direction of the bionic shark skin structures, where the maximum rate of the adhesive reduction reaches about 65%. Furthermore, the evolution of the directional diffusion for the water droplet, which is based on the change of the contact angle, was clearly observed, and the mechanism was also discussed by the models. Moreover, no-loss transportations were achieved successfully using the gradient adhesive force and superhydrophobicity on the surface by tuning the growth direction and modifying by fluorinated silane. Finally, this work gives a strategy for fabricating across-scale structures on micro- and nanometers, which have potential application in bioengineering, diversional targeting, and condenser surface.

Assessment of pharmacokinetics-pharmacodynamics to support omadacycline dosing regimens for the treatment of patients with acute bacterial skin and skin structure infections.

Pharmacokinetic-pharmacodynamic (PK-PD) relationships for efficacy were evaluated using data from omadacycline-treated patients with acute bacterial skin and skin structure infections (ABSSSI) enrolled in two phase 3 studies. Patients received omadacycline 100 mg intravenously (IV) every 12 hours for two doses, followed by 100 mg IV every 24 hours (q24h), with the option to switch to 300 mg oral (PO) q24h after 3 days or 450 mg PO q24h for two doses, followed by 300 mg PO q24h for a total duration of 7-14 days. Clinical response was evaluated at 48-72 hours [early clinical response (ECR)], end of treatment (EOT), and 7-14 days after EOT. Using a population pharmacokinetic (PK) model and PK data from patients with Staphylococcus aureus at baseline, omadacycline free-drug plasma area under the concentration-time curve (AUC) values were determined, and the relationships between free-drug plasma AUC:MIC ratio and dichotomous efficacy endpoints were evaluated. Using these relationships, the population PK model, simulation, and an omadacycline MIC distribution for S. aureus, mean percent probabilities of response were evaluated. Statistically significant PK--PD relationships were identified for ECR (P = 0.016 and 0.013 for optimized two- and three-group free-drug plasma AUC:MIC ratios, respectively). At an MIC value of 0.5 µg/mL, percent probabilities of model-predicted success for ECR based on the univariable PK-PD relationships using continuous and two-group free-drug plasma AUC:MIC ratio variables were 91.9 and 95.6%, respectively, for the IV-to-PO dosing regimen and 89.3 and 88.4%, respectively, for the PO-only dosing regimen. These data support for omadacycline IV-to-PO and PO-only dosing regimens for ABSSSI and an omadacycline susceptibility breakpoint of 0.5 µg/mL for S. aureus.

Rotational radiofrequency-based technology leads to adipose tissue reduction and contouring effect in the thighs, abdomen, and flanks.

BACKGROUND: Excess body adiposity and skin irregularities represent a major problem in today's society. Currently, radiofrequency-based devices constitute an increasingly popular medical-aesthetic application and a powerful non-invasive method to combat this problem. OBJECTIVE: This study aims to determine the efficacy and safety of the high-frequency device Zionic™ (Termosalud, Inc., Gijón, Spain) in reducing body contouring and improving skin appearance in the abdomen/flanks or thighs. MATERIALS AND METHODS: Thirty nine individuals were treated with the Zionic™ device in the abdomen/flanks or thighs. A total of 8 sessions of 40-50 min each, 72/96 h apart were performed. At baseline, body measurements were taken including photographs, body contours, and ultrasound scans to assess dermal thickness, dermal echogenicity, and subcutaneous fat thickness. The measurements were repeated after the eight sessions for comparison and analysis. Quantitative data was complemented with a customized survey to evaluate participants satisfaction level. RESULTS: At the follow-up visit, a significant average reduction of 3% in abdomen/flanks circumferences and 2% in thighs contours was noticed. Abdomen/flanks and thighs subcutaneous fat layer thickness was significantly reduced by 8% and 6%, respectively. Dermal echogenicity changes, related to skin collagen content and organization, showed non-significant increasing tendencies of 7% for abdomen/flanks and 8% for thighs. Thighs dermal thickness was significantly increased by 6%. Results were associated to a high satisfaction level (80%) and no severe adverse events. CONCLUSION: Zionic™ treatment is a safe, effective, and well-tolerated noninvasive procedure for body contouring and improvement of skin properties in abdomen, flanks, and thighs.

Progress in Topical and Transdermal Drug Delivery Research-Focus on Nanoformulations.

Skin is the largest organ and a multifunctional interface between the body and its environment. It acts as a barrier against cold, heat, injuries, infections, chemicals, radiations or other exogeneous factors, and it is also known as the mirror of the soul. The skin is involved in body temperature regulation by the storage of fat and water. It is an interesting tissue in regard to the local and transdermal application of active ingredients for prevention or treatment of pathological conditions. Topical and transdermal delivery is an emerging route of drug and cosmetic administration. It is beneficial for avoiding side effects and rapid metabolism. Many pharmaceutical, technological and cosmetic innovations have been described and patented recently in the field. In this review, the main features of skin morphology and physiology are presented and are being followed by the description of classical and novel nanoparticulate dermal and transdermal drug formulations. The biophysical aspects of the penetration of drugs and cosmetics into or across the dermal barrier and their investigation in diffusion chambers, skin-on-a-chip devices, high-throughput measuring systems or with advanced analytical techniques are also shown. The current knowledge about mathematical modeling of skin penetration and the future perspectives are briefly discussed in the end, all also involving nanoparticulated systems.

Dalbavancin for the treatment of acute bacterial skin and skin structure infections (ABSSSI) in pediatric patients: a case series.

Acute bacterial skin and skin-structure infections (ABSSSI) are a significant cause of morbidity in pediatric patients, requiring timely and effective treatment. Dalbavancin, a long-acting lipoglycopeptide antibiotic recently approved for pediatric use, offers advantages such as excellent bactericidal activity against Gram-positive bacteria (including multidrug-resistant pathogens) and high tissue penetration. We present a case series of pediatric patients with ABSSSI treated with dalbavancin. Five cases were described demonstrating the efficacy of dalbavancin in different clinical scenarios. Patients with complex skin conditions, including cellulitis and deep abscesses, benefited from dalbavancin therapy, achieving significant clinical improvement. Notably, dalbavancin facilitated early discharge, improving quality of life and reducing healthcare costs. These cases highlight the potential of dalbavancin as a valuable treatment option for ABSSSI in pediatric patients, particularly in settings where conventional therapies fail to achieve optimal clinical outcomes or prolonged hospitalization is not feasible. Further research is needed to clarify its role and optimize its use in pediatric patients with ABSSSI.

Impact of Iron Supplementation on Hospital Length of Stay for Pneumonia or Skin and Skin Structure Infections: A Retrospective Cohort Study.

Objectives: Pathogenic organisms utilize iron to survive and replicate and have evolved many processes to extract iron from human hosts. The goal of this study was to elucidate the impact of iron supplementation given in the setting of acute infection. Methods: This was a retrospective cohort study of Veterans Affairs patients who received intravenous antibiotics for pneumonia or skin and skin structure infections. Five-thousand subjects were included in each of the 2 cohorts: iron-receiving and non-iron-receiving. Data was analyzed using Fischer's Exact test if categorical and independent t-tests if continuous. Primary and secondary objectives analyzed with Cox proportional hazard regression and outcome rates estimated utilizing Kaplan-Meier method. Results: Five-thousand patients were included in each cohort. The iron cohort was significantly older (Mean-years: Iron = 71.6, No-iron = 68.9; mean-difference = 2.7, P < .0001) with reduced renal function (Mean-eGFR[mL/min/1.73 m²]: Iron = 67.2, No-iron = 77.4; mean-difference = 10.2, P < .0001). For the primary outcome, the iron cohort had a significantly longer mean length of hospital stay (10.4 days) compared to the no-iron cohort (8.7 days) (mean difference 1.7 days, P < .0001). Secondary outcome analysis showed the iron cohort received intravenous antibiotics for longer (Iron = 8.2 days, No-iron = 7.1 days; mean-difference = 1.1 days, P < .0001) with a higher proportion of 30-day readmissions (Iron = 15.6%, No-iron = 12.8%; proportion difference = 2.8%, P < .0001). No significant difference was found between cohort proportions for 30-day mortality (Iron = 12.7%, No-iron = 11.3%, proportion difference = 1.4%, P = .052). Conclusions: Baseline characteristic differences between cohorts is representative of patients who would be expected to require iron replacement therapy. Given the magnitude of primary and secondary-outcomes, further studies controlling for these factors would be warranted.

High-frequency Ultrasound in the Assessment before and after Applying HArmonyCa™.

AIM: To describe a clinical case of ultrasound (US) used to evaluate, before, post-immediately, and after 4 months, the facial application of a volumizing and biostimulating substance. BACKGROUND: Detecting the behavior of injected filler materials with high-frequency US-guided application is the future of natural facial rejuvenation with more predictable and satisfactory results. TECHNIQUE: A patient indicated for orofacial harmonization (OFH) procedures through volumizing and biostimulating material application was invited to participate. The technique was performed by applying HArmonyCa™ (Allergan Aesthetics, Irvine, CA, USA) in the gonial, preauricular, and bilateral lateral zygomatic angle regions. The first evaluations used the US images before and after product application with a Logiq e® high-frequency US device (GE Healthcare, Chicago, IL, USA) with a probe/linear transducer of 18 MHz. About 4 months after the procedure, a new assessment with the same initial acquisition pattern was performed. The first evaluation showed normal-looking anatomical structures without the esthetic material. Immediately after the procedure and 4 months later, the assessments presented semi-permanent esthetic fillers as dispersed lobulated hyperechogenic areas with a cloud aspect. CONCLUSION: High-frequency US was efficient in the static evaluation of HArmonyCa™ behavior on the facial skin. CLINICAL SIGNIFICANCE: The US-guided application of injectable products in specific areas has minimal side effects and contributes to more predictable and satisfactory results. How to cite this article: Gouveia RSA, Tostes LLL, Bezerra FV, et al. High-frequency Ultrasound in the Assessment before and after Applying HArmonyCa™. J Contemp Dent Pract 2024;25(1):10-14.

Evaluation of the anti-aging effects of Zinc-α2-glycoprotein peptide in clinical and in vitro study.

BACKGROUND: Skin aging, characterized by the deterioration of skin density and elasticity, is a common concern among individuals seeking to maintain a youthful appearance. Zinc-α2-glycoprotein (ZAG) is secreted by various body fluids, and is associated with lipolysis and identified as an atopic dermatitis biomarker. This study evaluated the potential of ZAG peptides, which exert multiple benefits such as anti-aging. MATERIALS AND METHODS: We conducted a 4-week clinical trial on patients with noticeable periorbital wrinkles (n = 22) using a ZAG peptide-containing product. The effects of the products on skin density, elasticity, and the depth of periorbital wrinkles were evaluated using Cutometer Dual MPA580, Ultrascan, and Antera 3D CS, respectively. The effect of ZAG peptides on UVB-treated keratinocyte cells was evaluated in vitro to understand the mechanisms underlying its effects against impaired skin barrier function, collagen degradation, and senescence. In addition, the effects of ZAG peptides on cell viability and expression of aging and skin barrier-related genes were assessed using cell counting kit assay and quantitative reverse transcription-polymerase chain reaction, respectively. RESULTS: The patients demonstrated improved skin density, elasticity, and reduced periorbital wrinkles. Further, more than 85% patients scored the product as satisfactory regarding anti-aging effects. Furthermore, ZAG peptides reduced SA-ß-gal staining, downregulated the senescence-related genes, and upregulated the skin barrier function-related genes in UVB-irradiated keratinocyte cells. CONCLUSIONS: Our clinical and in vitro findings showed that ZAG peptides exert anti-aging effects and improve skin barrier functions, suggesting their promising potential as therapeutic agents to combat skin aging and improve skin health.

Real-World Use of Dalbavancin for Treatment of Soft Tissue and Bone Infection in Children: Safe, Effective and Hospital-Time Sparing.

Acute bacterial skin and skin structure infections (ABSSSI) and osteoarticular infections compound the burden of morbidity, mortality and prolonged hospitalizations among gram-positive infections. Dalbavancin, a second-generation, intravenous lipoglycopeptide, due to its prolonged half-life, can be a valuable alternative in their treatment when administered as inpatient treatment at the price of an extended hospital stay. Between October 2019 and September 2023, 31 children and adolescents were treated with dalbavancin because of bone and joint infections (n = 12 patients, 39%), ABSSSI (n = 13 patients, 42%), mainly for the limbs, facial cellulitis or complicated ABSSSI (n = 6 patients, 19%), at five Italian pediatric centers. Microbiological study provided gram-positive bacterial isolate in 16 cases, in 11 cases from a positive blood culture; 9 of them were MRSA. Twenty-five patients were initially treated with a different antibiotic therapy: beta-lactam-based in 18 patients (58%), glycopeptide-based in 15 patients (48%) and daptomycin in 6 (19%). The median time that elapsed between admission and start of dalbavancin was 18 days. A total of 61 doses of dalbavancin were administered to the 31 patients: 16 received a single dose while the remaining 15 patients received between two (n = 9) and nine doses. The frequency of administration was weekly in five cases or fortnightly in nine patients. Median length of stay in hospital was 16 days. Median time to discharge after the first dose of dalbavancin was 1 day. Treatment was very well-tolerated: of the 61 administered doses, only four doses, administered to four patients, were associated with an adverse event: drug extravasation during intravenous administration occurred in two patients, with no sequelae; however, in two patients the first administration was stopped soon after infusion start: in one (ID #11), due to headache and vomiting; in another (ID #12) due to a systemic reaction. In both patients, drug infusion was not repeated. None of the remaining 29 patients reported treatment failure (resistant or recurrent disease) or an adverse effect during a median follow-up time of two months. The use of dalbavancin was safe, feasible and also effective in shortening the hospital stay in children and adolescents.

Diagnosing, assessing and managing cellulitis.

Cellulitis is an acute bacterial infection that affects the deep dermis and surrounding subcutaneous tissue. Although it is a common condition, it is often misdiagnosed because it can mimic a range of conditions that also cause inflamed, red, irritated and painful skin. Such misdiagnoses may lead to unnecessary hospital admissions and antibiotic overuse, with most alternative diagnoses being non-infectious. Undertaking a holistic patient assessment, skin assessment and thorough clinical history is important in the diagnosis of cellulitis, and it is vital to use a collaborative multidisciplinary approach in its acute management and to prevent recurrence. This article defines the term cellulitis and explores its presenting features. The author also discusses the associated risk factors, clinical assessment techniques and effective management strategies, as well as outlining the actions that nurses can take to prevent recurrence.

Aging Skin and Wound Healing.

Responsible for many essential functions of life, human skin is made up of many components, each of which undergoes significant functional changes with aging and photodamage. Wound healing was previously thought to be defective in the elderly given the higher presence of chronic wounds and the longer time required for re-epithelialization of acute wounds. However, these notions have been challenged in recent research, which has shown that wound healing in the elderly is delayed but not defective. Poor healing of chronic wounds in older populations is more often attributable to comorbid conditions rather than age alone.

Preventing, assessing and treating skin tears.

Skin tears are acute wounds caused by mechanical forces resulting in the separation of the skin's outer layers. Skin tears are more likely to occur in vulnerable people such as older people and people with neurodegenerative conditions. Rising life expectancy means that the number of patients with skin tears is expected to increase. This article describes the characteristics of skin tears, details the risk factors for skin tears and explains the importance of using a holistic, evidence-based and person-centred approach to skin tear prevention, assessment and treatment. The article outlines the crucial role of nurses as part of the multidisciplinary team in the management of skin tears.

A Cluster Validity Index-Based Objective Criteria for Aesthetic Evaluation of Periorbital Treatment.

Purpose: Dark circles and pigmentation around the eyes are common reasons people see dermatologists. An effective assessment of the severity of infraorbital color and texture differences is critical for determining appropriate treatment. Evaluation of the visual severity of cases is mostly based on visual inspection. Treatment efficiency is often measured using patient questionnaires in many cases. The subjectivity of assessments may lead to a prolonged healing process, misdiagnosis, and excessive use of drugs or chemicals. Patients and Methods: In this study, a computer-aided objective evaluation approach was proposed for grading periorbital facial rejuvenation. This approach is based on the analysis of numerical features extracted from different facial regions in digital images. Healing was objectively graded by evaluating data clusters formed using the extracted features. Accordingly, an increase in the visual similarity between paired facial regions is accepted as an indicator of healing, which directly affects the form of data clusters. An intracluster validity index was measured to evaluate the clusters as dense and well separated. A total of 144 facial regions were extracted and examined, and the automatically calculated grades were compared with expert evaluations. Results: The cosmetic effects of the experimental drug were evaluated during the experiments, and expert grades were accepted as the ground truth. The results show that the proposed automated grading approach can evaluate rejuvenation with an accuracy of up to 0.91 accuracy in the upper orbital region. Conclusion: This study concluded that the proposed data-clustering-based approach is promising and can be functional without any special instruments.

Skin quality sensor to evaluate vibration and friction generated when sliding over skins.

OBJECTIVE: The mechanical condition and tactile evaluation of skin are essential for the development of skin care products. Most of the existing commercial instruments and studies aim to evaluate the skin surface by pressing it for hardness or by using imaging sensors, but there have been few instrumental measurements employing rubbing motion. Here, we have developed a sensor specialized for tactile sensation and the contact phenomenon during skin rubbing. METHODS: The developed sensor has three features: It can measure body parts including cheeks and arms, automate the rubbing motion of the probe and measure vibration and friction simultaneously. It is hand-held, with metal probes that rub the skin surface while rotating under a motor drive; it has an accelerometer and a force sensor beneath the probe measuring vibration and friction forces. To evaluate the validity of the sensor's measurements, artificial skin models were measured using the developed sensor and commercially available sensors and the results were compared. The relationship between the sensor output, surface roughness measurement and sensory evaluation was also investigated. Additionally, we evaluated the inter-rater reliability when measuring actual skin. RESULTS: The measurements of five artificial skin models with different surface shapes showed a high correlation (r = 0.99) between the vibration intensity values evaluated by the developed sensor and those measured by a tri-axial acceleration sensor attached to a fingernail. The correlation coefficient between the vibration intensity values and surface roughness was r = 0.91, and the correlation with the sensory evaluation score of roughness was r = 0.99. The friction coefficients measured by the developed sensor and the force plate had r = 0.93, based on measurements of five artificial skin models with different friction conditions. The inter-rater correlation coefficients between the three participants of the developed sensor were as high as 0.92 and 0.94 for the vibration and friction measurements respectively. CONCLUSION: The vibration intensities and friction coefficients from the sensor were highly correlated with those of the conventional sensor. The inter-rater reliability was also high. The developed sensor can be useful for tactile evaluation in skin-care product development.

OBJECTIF: l'état mécanique et l'évaluation tactile de la peau sont essentiels au développement de produits de soins de la peau. La plupart des instruments disponibles sur le marché et des études publiées à ce jour évaluent la surface de la peau en la comprimant pour déterminer sa dureté ou en utilisant des capteurs d'imagerie, mais il n'y a eu que peu de mesures instrumentales utilisant le mouvement de frottement. Ici, nous avons développé un capteur spécialisé pour la sensation tactile et le phénomène de contact lors du frottement de la peau. MÉTHODES: le capteur développé possède trois caractéristiques : il permet d'exercer des mesures sur plusieurs parties du corps, y compris les joues et les bras ; il automatise le mouvement de frottement de la sonde et il mesure simultanément les vibrations et les frottements. Tenu à la main, doté de sondes en métal qui frottent la surface de la peau tout en tournant sous l'action d'un moteur, il est équipé d'un accéléromètre et d'un capteur de force situé sous la sonde qui mesure les forces de vibration et de frottement. Pour déterminer la validité des mesures du capteur, des modèles de peau artificielles ont été évalués à l'aide du capteur développé et de capteurs déjà disponibles sur le marché, et les résultats ont été comparés. Le lien entre les mesures réalisées à l'aide du capteur, la mesure de la rugosité de la surface de la peau et l'évaluation sensorielle a également été étudié. En outre, nous avons évalué la fiabilité inter-évaluateurs lors de la mesure réelle de la peau. RÉSULTATS: les mesures de cinq modèles de peau artificielle avec des formes de surface différentes ont montré une forte corrélation (r = 0,99) entre les valeurs d'intensité des vibrations évaluées par le capteur développé et celles mesurées par un capteur d'accélération triaxial fixé à un ongle. Le coefficient de corrélation entre les valeurs d'intensité des vibrations et la rugosité de la surface était r = 0,91, et la corrélation avec le score d'évaluation sensorielle de la rugosité était r = 0,99. Les coefficients de frottement mesurés par le capteur développé et la plaque de force étaient r = 0,93, sur la base des mesures de cinq modèles de peau artificielle avec des conditions de frottement différentes. Les coefficients de corrélation inter-évaluateurs entre les trois participants utilisant le capteur développé ont atteint 0,92 et 0,94 pour les mesures de vibrations et de frottement, respectivement. CONCLUSION: les intensités des vibrations et les coefficients de frottement du capteur se sont avérés fortement corrélés avec ceux du capteur conventionnel. La fiabilité inter-évaluateurs était également élevée. Le capteur développé peut être utile pour l'évaluation tactile lors du développement de produits de soins de la peau.

Interspecific differences and ecological correlations between scale number and skin structure in freshwater fishes.

Fish skin is mainly composed of the epidermis, dermis, and its derivative scales. There is a wide diversity in scale number in fishes, but the diversity of skin structure lacks systematic histological comparison. This research aimed to improve our understanding of the functional relationship between the scale number and the skin structure in freshwater fishes and to determine which ecological factors affect the scale number and skin structure. First, we presented a method to quantify skin structure in fish and histologically quantified the skin structure of 54 freshwater fishes. Second, we collected the scale number and habitat information of 509 Cyprinidae fishes in China and explored which ecological factors were related to their scale number. Third, common carp and scaleless carp were used as models to study the effects of scale loss on swimming. We found a strong negative correlation between scale thickness and scale number. The main factor affecting the skin structure of fishes was the species' water column position, and the skin of benthic fishes was the most well-developed (thicker skin layers (dermis, epidermis) or more/larger goblet cells and club cells). The scale number was related to two factors, namely, temperature and water column position, and cold, benthic and pelagic adaptation may have contributed to increased scale numbers. Only in benthic fishes, the more well-developed their skin, the more scales. In common carp, scale loss did not affect its swimming performance. In summary, we suggest that there is a rich diversity of skin structure in freshwater fishes, and the scales of fish with well-developed skin tend to degenerate (greater number/smaller size/thinner, or even disappear), but the skin of fish with degenerated scales is not necessarily well developed.