Biological Skin Research Articles

Auto-Resonant Tuning for Capacitive Power and Data Telemetry Using Flexible Patches

This brief proposes and demonstrates a reliable power and data transfer scheme for biomedical implants through a resonant capacitive link. Flexible, conformable, and biocompatible patches are adopted with an automatic resonant frequency calibration technique for the first time. A voltage feedback network, a Class- ${D}$ driver, and a custom algorithm have been developed for the low overhead calibration. An ex vivo chicken skin tissue-based experiment with 4 cm2 flexible, conformal capacitive patches demonstrated the method. Experimental results show that the power delivered to the load (PDL) of the link extends up to 150 mW and maximum power transfer efficiency (PTE) of the link is 54%. A simultaneous data transfer with a rate of up to 170 kbps alongside power transfer using 1.5 to 2 mm-thick biological skin tissue has been achieved.

Relationship of transcutaneous oxygen tension with age and skin elasticity in Korean women.

Oxygen has several positive effects on the skin, including improving collagen synthesis and accelerating wound healing. However, only a few studies have investigated the relationship between skin oxygenation and skin aging parameters. Therefore, this study aimed to assess the correlation between skin oxygenation and skin aging parameters-elasticity, hydration, sebum, color (lightness, redness), and blood perfusion-in Korean women. We evaluated the transcutaneous partial pressure of oxygen, also known as transcutaneous oxygen tension (TcPO2 ), and skin aging parameters, including elasticity, hydration, sebum, color (lightness or redness), and blood perfusion, in the cheek of 34 healthy women (aged 20-69years) and assessed the correlation between TcPO2 and other skin aging parameters using IBM SPSS Statistics 25 software (SPSS Inc). Facial TcPO2 was negatively correlated with age (P<.05). There were positive correlations between facial TcPO2 and elasticity parameters (P<.01). We noted no correlation between facial TcPO2 and skin lightness; however, skin lightness tended to slightly improve with increasing TcPO2 . Skin aging parameters, including hydration, sebum, skin redness, and blood perfusion, showed no correlations with TcPO2 . In Korean women, facial TcPO2 tends to decrease with increasing age and is positively correlated with gross, net, and biological skin elasticity. Therefore, this study demonstrated that oxygen tension of facial skin can be a major causative factor of skin aging.

The Use of Dehydrated Human Amniotic/Chorionic Membrane Skin Substitute in the Treatment of Pediatric Facial Burn.

Facial burns have lasting physical and psychological effects on pediatric patients. Proper management to minimize morbidities challenges reconstructive surgeons. New technologies allowed the development of skin substitutes such as amniotic and chorionic membranes, yet the use of these skin dressings and their impact on burn outcomes have not been sufficiently studied to guide practices. The objective of this study is to report on the outcomes of dehydrated amniotic membrane as a biologic skin dressing in pediatric facial burn injury compared to cadaveric allografts. Retrospective review of data collected from our institutional burn registry from 2012 to 2016. The study population included patients younger than 16 years with facial burns. Patients between 2012 and 2014 received cadaveric allografts, whereas during 2015 to 2016 patients received dehydrated human amniotic/chorionic membrane as standard treatment. Demographic characteristics and outcome measures were compared between the 2 groups. Included 30 patients with a mean age of 3.7 years and with an average total body surface area burn of 6.8% (2%-27%). Mean injury severity scores did not significantly differ between both groups, 1.8 in amniotic group versus 2.3 in cadaveric skin group (P > 0.05). There were 4 complications (3 hypertrophic scars and 1 wound infection) in the cadaveric allografts group versus no complications in the amniotic membrane group (P < 0.05). Dehydrated amniotic/chorionic membrane wound dressings are a safe alternative to cadaveric allografts in treating pediatric partial thickness facial burns.

Evolution of Biological Bandages as First Cover for Burn Patients.

Significance: Cutaneous wound regeneration is vital to keep skin functions and for large wounds, to maintain human survival. In a deep burn, the ability of the skin to heal is compromised due to the damage of vasculature and resident cells, hindering a coordinated response in the regeneration process. Temporal skin substitutes used as first cover can play a major role in skin regeneration as they allow a rapid wound covering that, in turn, can significantly reduce infection risk, rate of secondary corrective surgeries, and indirectly hospitalization time and costs.Recent Advances: Skin was one of the first tissues to be bioengineered providing thus a skin equivalent; however, what is the current status subsequent to 40 years of tissue engineering? We review the classic paradigms of biological skin substitutes used as first cover and evaluate recent discoveries and clinical approaches adapted for burn injuries cover, with an emphasis on innovative cell-based approaches.Critical Issues: Cell-based first covers offer promising perspectives as they can have an active function in wound healing, such as faster healing minimizing scar formation and prepared wound bed for subsequent grafting. However, cell-based therapies encounter some limitations due to regulatory hurdles, as they are considered as “Advanced Therapy Medicinal Products,” which imposes the same industry-destined good manufacturing practices as for pharmaceutical products and biological drug development.Future Directions: Further improvements in clinical outcome can be expected principally with the use of cell-based therapies; however, hospital exemptions are necessary to assure accessibility to the patient and safety without hindering advances in therapies.

Evidence for Healing Diabetic Foot Ulcers With Biologic Skin Substitutes

Development of diabetic foot ulcers is a common complication of diabetes. Standard-of-care (SOC) therapy alone is often not sufficient to heal these wounds, resulting in application of adjuvant wound therapies including biologic skin substitutes. Although a variety of products exist, it has been difficult to formulate conclusions on their clinical efficacy. We therefore performed a systematic review and meta-analysis on the efficacy of healing diabetic foot ulcers with biologic skin substitutes. A systematic review was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). Four electronic databases (PubMed/MEDLINE, EMBASE [Ovid], Cochrane CENTRAL [Ovid], and Web of Science) were searched from inception through February 27, 2019. Searches included keywords and subject headings pertaining to 3 main concepts: biologic skin substitutes, wound healing, and diabetic foot ulcers. Cochrane randomized controlled trial filters were used to narrow results. Data were extracted from 54 included articles, and risk-of-bias assessments were conducted by 2 independent reviewers. The primary objective was to calculate a pooled risk ratio for the proportion of wounds completely closed by 12 weeks. Secondary objectives included a pooled risk ratio for the proportion of wounds completely closed by 6 weeks and mean time to healing. Twenty-five studies were identified that assessed the proportion of complete wound closure by 12 weeks. We found that wounds treated with biologic dressings were 1.67 times more likely to heal by 12 weeks than those treated with SOC dressings (P < 0.00001). Five studies assessed the proportion of complete wound closure by 6 weeks. Wounds treated with biologic dressings were 2.81 times more likely to heal by 6 weeks than those treated with SOC dressings (P = 0.0001). Descriptively, 29 of 31 studies that assessed time to healing favored biologic dressings over SOC dressings. This systematic review provides supporting evidence that biologic skin substitutes are more effective than SOC dressings at healing diabetic foot ulcers by 12 weeks. Future studies must address the relative benefits of different skin substitutes as well as the long-term implications of these products and their financial considerations.

Large-Area Soft e-Skin: The Challenges Beyond Sensor Designs

Sensory feedback from touch is critical for many tasks carried out by robots and humans, such as grasping objects or identifying materials. Electronic skin (e-skin) is a crucial technology for these purposes. Artificial tactile skin that can play the roles of human skin remains a distant possibility because of hard issues in resilience, manufacturing, mechanics, sensorics, electronics, energetics, information processing, and transport. Taken together, these issues make it difficult to bestow robots, or prosthetic devices, with effective tactile skins. Nonetheless, progress over the past few years in relation with the above issues has been encouraging, and we have achieved close to providing some of the abilities of biological skin with the advent of deformable sensors and flexible electronics. The naive imitation of skin morphology and sensing an impoverished set of mechanical and thermal quantities are not sufficient. There is a need to find more efficient ways to extract tactile information from mechanical contact than those previously available. Renewed interest in neuromorphic tactile skin is expected to bring some fresh ideas in this field. This article reviews these new developments, particularly related to the handling of tactile data, energy autonomy, and large-area manufacturing. The challenges in relation with these advances for tactile sensing and haptics in robotics and prosthetics are discussed along with potential solutions.

Syndrome de Sweet médicamenteux à l’hydroxychloroquine : à propos de 2 cas

IntroductionHydroxychloroquine is widely prescribed in systemic lupus erythematosus. Dermatologic adverse drug reactions are rare but can mimic a disease specific manifestation of lupus. Exceptionally, Sweet's syndrome, or acute febrile neutrophilic dermatosis, may be drug-induced. Case reportsTwo patients aged 31 and 42 years were treated with hydroxychloroquine for systemic lupus and Sjogren's syndrome, respectively. Three weeks after starting treatment, they had a febrile, purple and erythematous papular rash of the trunk and limbs. There was a biological inflammatory syndrome and skin biopsy disclosed an infiltrate of the dermis rich in neutrophils. Lesions regressed after stopping hydroxychloroquine and introducing systemic corticosteroid therapy. Allergologic tests discussed the differential diagnosis with a delayed-type hypersensitivity reaction. ConclusionWe report two exceptional cases of drug-induced Sweet's syndrome related to hydroxychloroquine treatment in autoimmune rheumatic diseases.

Molecular Functionality of Cytochrome P450 4 (CYP4) Genetic Polymorphisms and Their Clinical Implications.

Enzymes in the cytochrome P450 4 (CYP4) family are involved in the metabolism of fatty acids, xenobiotics, therapeutic drugs, and signaling molecules, including eicosanoids, leukotrienes, and prostanoids. As CYP4 enzymes play a role in the maintenance of fatty acids and fatty-acid-derived bioactive molecules within a normal range, they have been implicated in various biological functions, including inflammation, skin barrier, eye function, cardiovascular health, and cancer. Numerous studies have indicated that genetic variants of CYP4 genes cause inter-individual variations in metabolism and disease susceptibility. Genetic variants of CYP4A11, 4F2 genes are associated with cardiovascular diseases. Mutations of CYP4B1, CYP4Z1, and other CYP4 genes that generate 20-HETE are a potential risk for cancer. CYP4V2 gene variants are associated with ocular disease, while those of CYP4F22 are linked to skin disease and CYP4F3B is associated with the inflammatory response. The present study comprehensively collected research to provide an updated view of the molecular functionality of CYP4 genes and their associations with human diseases. Functional analysis of CYP4 genes with clinical implications is necessary to understand inter-individual variations in disease susceptibility and for the development of alternative treatment strategies.

Mimicking Human and Biological Skins for Multifunctional Skin Electronics

AbstractElectronic skin (e‐skin) technology is an exciting frontier to drive the next generation of wearable electronics owing to its high level of wearability, enabling high accuracy to harvest information of users and their surroundings. Recently, biomimicry of human and biological skins has become a great inspiration for realizing novel wearable electronic systems with exceptional multifunctionality as well as advanced sensory functions. This review covers and highlights bioinspired e‐skins mimicking perceptive features of human and biological skins. In particular, five main components in tactile sensation processes of human skin are individually discussed with recent advances of e‐skins that mimic the unique sensing mechanisms of human skin. In addition, diverse functionalities in user‐interactive, skin‐attachable, and ultrasensitive e‐skins are introduced with the inspiration from unique architectures and functionalities, such as visual expression of stimuli, reversible adhesion, easy deformability, and camouflage, in biological skins of natural creatures. Furthermore, emerging wearable sensor systems using bioinspired e‐skins for body motion tracking, healthcare monitoring, and prosthesis are described. Finally, several challenges that should be considered for the realization of next‐generation skin electronics are discussed with recent outcomes for addressing these challenges.

Araticum (Annona crassiflora Mart.) as a source of nutrients and bioactive compounds for food and non-food purposes: A comprehensive review.

Araticum (Annona crassiflora Mart.) is a fruitful tree native to the Brazilian Cerrado biome that holds high nutritional, functional and economic potential. This plant has been used since ancient times by folk medicine for the treatment of several pathological conditions. There has been increasing interest in the development of pulp-based food products as well as the by-products utilization to obtain value-added ingredients. Understanding the chemical composition and biological activities of different botanical parts of Annona crassiflora Mart. provides a basis to support future researches and applications. In this context, this paper carries out an exhaustive review of the scientific literature, on the main phytochemicals of different botanical parts of Annona crassiflora Mart. (fruit, leaves, stem and root) and their biological activities, assessing their potential uses for several industrial segments. Annona crassiflora Mart. fruits and especially their by-products (peel and seeds) and leaves have been shown a wide range of bioactive compounds such as phenolic compounds, alkaloids, annonaceous acetogenins, tocols, carotenoids, phytosterols, dietary fiber, vitamins, minerals and essential oils. These compounds contribute to various biological activities, including antioxidant, hepatoprotective, anti-inflammatory, antitumoral, analgesic, antidiabetic, skin healing, antidiarrhoeic, antimicrobial, antiparasitic, insecticide and herbicide activities of Annona crassiflora Mart. extracts. Therefore, these findings demonstrate that Annona crassiflora Mart. fruit, by-products and leaves can be excellent candidates to be used as functional foods and/or sources for obtaining bioactive compounds for the food, cosmetics and pharmaceutical applications.

Two-temperature high-order lagging effect of living tissue subjected to moving heat source

The work is dealing with the studying the effect of the moving heat source with constant velocity on the biological skin tissue. The heat conduction equation has been considered to be a two-temperature high-order thermal lagging model. A limited length of skin tissue has been constructed to be initially at rest and the first end subjected to constant heat flux while the second end has zero heat flux. Laplace transform has been applied and the inversion has been calculated numerically. The results show that the two-temperature parameter and the value of the heat source velocity have significant effects on the conductive and dynamical temperatures increment.

Three-dimensional biological tissue under high-order effect of two-temperature thermal lagging to thermal responses due to a laser irradiation

Using the lasers and heat transfer through biological skin tissue is essential for the processes of the medical treatment. Thus, two-temperature bio-heat transfer equations were introduced and used to discuss the variation of temperature in a laser-irradiated biological tissue. As a result, the Laplace and Fourier transform techniques have been applied, and the solutions of the conductive temperature have been represented in figures. The two-temperature parameter, the penetration depth parameter, the dimensions of the rectangular laser pulse, and the power density of laser irradiation parameter have significant effects on the thermal waves through the skin tissue.

Integrated Soft Ionotronic Skin with Stretchable and Transparent Hydrogel-Elastomer Ionic Sensors for Hand-Motion Monitoring.

Skin-like stretchable sensors with the flexible and soft inorganic/organic electronics have many promising potentials in wearable devices, soft robotics, prosthetics, and health monitoring equipment. Hydrogels with ionic conduction, akin to the biological skin, provide an alternative for soft and stretchable sensor design. However, fully integrated and wearable sensing skin with ionically conductive hydrogel for hand-motion monitoring has not been achieved. In this article, we report a wearable soft ionotronic skin (iSkin) system integrating multichannel stretchable and transparent hydrogel-elastomer hybrid ionic sensors and a wireless electronic control module. The ionic sensor is of resistive type and fabricated by curing ionic hydrogel precursor on a benzophenone-treated preshaped elastomer to form a hydrogel-elastomer hybrid structure. The hydrogel-elastomer hybrid iSkin is highly stretchable (∼300% strain), transparent (∼95% transmittance in the visible light range), and lightweight (<22 g). Experiments demonstrate that the fully integrated iSkin system can conformably attach onto the dexterous hands for recognizing the joint proprioception and hand gesture, and understanding the sign language. Our iSkin system would also provide a test bed for customized material selection and construction in a variety of applications.

Biological Pattern Based on Reaction-Diffusion Mechanism Employed as Fabrication Strategy for a Shell Structure

This paper examines how generative architectural design processes aim to apply the principles of biological morphogenesis to the design and building of mechanical or architectural structures. Despite the revolution in computation aided design and interdisciplinary upgrades of digital fabrication technologies, design processes fail to acknowledge materials, tools and construction logic in an early design stage, as manifested in nature. The objective of this paper is to introduce a design workflow, based on the knowledge of the tool, material properties, design intuition and aesthetic criteria, to translate biological skin patterns to fabrication processes, incorporating three materials and procedures in a single parametric workflow. Mesh relaxation processes and weighted mesh graph representations are examined as design potentials for stripe organization in fabrication in analogy to numerical simulations of a reaction-diffusion (RD) mechanism. A thin shell and landscape emerge as a self-organizing system in equilibrium. The paper argues that skin patterns in fabrication open a new field for interdisciplinary investigation.

Primena algoritama segmentacije mreže kao strategija za fabrikaciju - generisanje uzoraka na osnovu mehanizma reakcije-difuzije

This paper examines how the evolution of architectural generative design processes aim to apply similar physical and geometrical principles of biological processes taking place during development and to translate them to fabrication processes. In analogy to the reaction-diffusion mechanism for biological pattern prediction, the logic of stripe is used as construction system and examined for its structural behaviour. Both, mesh relaxation processes and weighted mesh graphs representations are employed as design tools for the construction of a minimal thin shell structural skin with branching topologies. Eventually the design workflow is extended to engage also collaborative fabrication processes and to steer the design based on intuition, knowledge of the fabrication tools, properties of the materials, manufacturing simulations and logic of assemble. This approach could lead to the optimization of material usage and machine time and facilitate the assembly process of a physical object which integrates the whole process into its form. The outcomes have been used to fabricate a prototype, using three different materials and digital fabrication methods, to examine the stability and the mechanical connectivity by taking in count the tolerances. The paper argues that biological skin patterns and segmentation in fabrication open a new field of interdisciplinary investigation and architectural applications.

Comparative study of silver-sulfadiazine-impregnated collagen dressing versus conventional burn dressings in second-degree burns.

Background:The advantages of biological skin dressings like collagen are well-known. It makes wound impermeable to bacteria and creates the most physiological interface between the wound surface and the environment. Silver-sulfadiazine-impregnated collagen (SIC) is a type 1 collagen impregnated with silver sulfadiazine (SSD)-loaded alginate microspheres to deliver SSD in a controlled fashion to manage infected burn wounds for an extended period of time with lesser dressing changes.Materials and Methods:In this study, we used SIC for the treatment of second-degree burn wounds in 25 patients and compared with similar burn wounds in 25 patients treated with conventional dressings.Results:For SIC-treated group, we observed improved wound healing in all the patients after 7 days except two patients who required skin grafting, and none of them had any serious complications. For conventionally treated group, improved wound healing was seen in 14 patients, whereas the rest of the patients required prolong dressing or skin grafting. All the patients who were treated with SIC were satisfied with healing of wound and pain relief.Conclusion:Second-degree burn wounds are well-treated with SIC in the form of good healing, control of infection, and reducing pain without any serious complications when compared with conventional dressing.

A review on biocompatibility nature of hydrogels with 3D printing techniques, tissue engineering application and its future prospective

Recently, tissue engineering (TE) is one of the fast growing research fields due the accessibility of extra-molecular matrix (ECM) at cellular and molecular level with valuable potential prospective of hydrogels. The enhancement in the production of hydrogel-based cellular scaffolds with the structural composition of ECM has been accelerated with involvement of rapid prototyping techniques. Basically, the recreation of ECM has been derived from naturally existed or synthetic hydrogel-based polymers. The rapid utilization of hydrogels in TE puts forward the scope of bioprinting for the fabrication of the functional biological tissues, cartilage, skin and artificial organs. The main focus of the researchers is on biofabrication of the biomaterials with maintaining the biocompatibility, biodegradability and increasing growth efficiency. In this review, biological development in the structure and cross-linking connections of natural or synthetic hydrogels are discussed. The methods and design criteria that influence the chemical and mechanical properties and interaction of seeding cells before and after the implantations are also demonstrated. The methodology of bioprinting techniques along with recent development has also been reviewed. In the end, some capabilities and shortcomings are pointed out for further development of hydrogels-based scaffolds and selection of bioprinting technology depending on their application.

Beneficial Effects of Marine Algae-Derived Carbohydrates for Skin Health.

Marine algae are considered to be an abundant sources of bioactive compounds with cosmeceutical potential. Recently, a great deal of interest has focused on the health-promoting effects of marine bioactive compounds. Carbohydrates are the major and abundant constituent of marine algae and have been utilized in cosmetic formulations, as moisturizing and thickening agents for example. In addition, marine carbohydrates have been suggested as promising bioactive biomaterials for their various properties beneficial to skin, including antioxidant, anti-melanogenic and skin anti-aging properties. Therefore, marine algae carbohydrates have potential skin health benefits for value-added cosmeceutical applications. The present review focuses on the various biological capacities and potential skin health benefits of bioactive marine carbohydrates.

The isomorphism hypothesis: The prisoner's dilemma as intertemporal allocation, and vice versa

Economists model the choice of the current self in intertemporal allocation as the outcome of identity: the current and future selves belong to the same decision maker by the sheer fact they reside in the same “biological skin” defined by biological identity. The economists should be consistent and likewise model the choice of each player in the prisoner's dilemma or, generally, the social dilemma as the outcome of identity: the selves of the players belong to the same decision maker by the sheer fact they reside in the same “social skin” defined by social identity. If the economists consider cooperation rather than defection to be the rational strategy of the current self in intertemporal allocations, they should be consistent and consider cooperation rather than defection to be the rational strategy of each player in social dilemmas. Symmetrically, if the economists judge defection rather than cooperation to be the rational strategy in social dilemmas, it behooves them to also judge defection rather than cooperation to be the rational strategy in intertemporal allocations.

Role Differences in Healthcare: Overcoming Borders through Semiotic Skin is the Basis for Communication

Role differences in healthcare systems are the very foundation of communication in this specific field of environment. It has to be understood as a collective corporation between collective individuals and thus connect through intertwined border zones. These border zones between collective communicators holds the notions of individuality, which is represented in the ability to decipher and negotiate the multiple layers in the communicative border zone. These processes in border zones of persons - in relation with others - are dealt with by the Semiotic Skin Theory. In addition, the biological skin is central for human lives and the Semiotic Skin is conceptualized as a socio-somatic-semiotic, layered and dynamic membrane that operates as a semi-permeable, communicative boundary. A constant interpretation between a self-reflecting system and an unending spiral of semiosis is the emergent of the semiotic skin. It creates a semi-permeable barrier that holds the very notions of the multi-layered skin-on-the-skin that is reflected in an embodied communication between humans and environment. In this theoretical understanding of an embodied aspect of not only meaning-making but also the regulative aspect of embodied interaction with others, the very idea of borders of individuality becomes the notion of interpretation. Any communication in a medical setting involves actions on the border of mutual understanding - e.g. communication between a pediatrician and a child. The concepts of a collective patient and a collective doctor are introduced as to understand the aspects of the multiple dynamics of the semiotic skin as the holder of an individual's personal ideas/interpretations in the interaction with one other person, holding multiple aspects from others as well. Examples of the interaction between patients and the healthcare system in Denmark illustrate how a new theoretical and practical performance of mastering the communicative partnership in the cross field between the healthcare system and psychology is born.