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Skin tissue is a kind of complex biological material abundant with fibers. A new constitutive model, relating macroscopic responses with microstructural fiber configuration alteration, is developed to investigate the stress softening behaviors of skin tissue observed during cyclic loading–unloading tests. Two influential factors are introduced to describe the impact of fiber configuration change and stretch-induced damage. The present model achieves good agreement between predicted stress distribution of human skin and corresponding ex vivo experimental data obtained from the literature, affirming its capability to effectively capture the characteristic softening behaviors of human skin under cyclic loading conditions. [ABSTRACT FROM AUTHOR]

The skin is crucial for homeostasis and body defense, requiring quick healing to maintain internal balance. Initially used for bone repair, calcium hydroxyapatite (HAp) is now being studied for soft tissue engineering. This literature review investigated HAp’s role in tissue repair through searches on PubMed, Scopus (Elsevier), Science Direct, Springer Link, and Google Scholar databases without time restrictions, using keywords “hydroxyapatite AND skin AND wound” and “hydroxyapatite AND skin repair”. Inclusion criteria encompassed in vivo studies in humans and animals, English publications, full access, and sufficient data on HAp’s role in tissue repair. Exclusions included duplicates, unrelated articles, editor letters, reviews, comments, conference abstracts, dissertations, and theses. Out of the 472 articles initially identified, 139 met the inclusion criteria, with 21 focusing on HAp for tissue repair. Findings indicate that HAp and nano-HAp in skin regeneration are promising, especially when combined with other biomaterials, offering antimicrobial and anti-inflammatory benefits and stimulating angiogenesis. This suggests their potential application in dermatology, surgery, and dentistry, extending HAp’s versatility from hard tissues to enhancing critical properties for soft tissue repair and accelerating healing.

Stevens Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe cutaneous adverse reactions characterised by keratinocyte apoptosis, necroptosis and epidermal detachment. Several cytokines and cytotoxic proteins have been shown to be elevated in the blood and skin of SJS/TEN sufferers and biologics such as intravenous immune globulin and tumour necrosis factor (TNF)‐alpha inhibitors have demonstrated good therapeutic potential. The exact pathogenic model of SJS/TEN however remains elusive. This systematic review aimed to evaluate the case–control studies of cytokines and cytotoxic proteins in the blister fluid and skin of adults with Stevens Johnson syndrome and/or toxic epidermal necrolysis. This review was registered with INPLASY and conducted in accordance with the PRISMA reporting guidelines. Potential bias was assessed using the NIH criteria. Eleven articles describing results from 96 cases and 170 controls were included. Fas, Fas ligand, Interleukin (IL)‐8 and B‐cell lymphoma (Bcl)‐2 were elevated in SJS/TEN blister fluid and skin tissue, compared with healthy controls. IL‐2, IL‐6, TNF‐alpha, tumour necrosis factor‐related apoptosis‐inducing ligand (TRAIL), interferon‐gamma and matrix metalloproteinase‐2 were elevated in SJS/TEN blister fluid compared with fluid sampled from lesional controls. Granulysin, IL‐33, TGF‐beta‐1 and IL‐13 were elevated in SJS/TEN skin tissue compared with lesional lichen planus tissue, as was IL‐13, IFN‐gamma, IL‐2 and IL‐5, when compared with erythema multiforme tissue. A wide array of cytokines and cytotoxic proteins are present at higher concentrations in the blister fluid and skin tissue of SJS/TEN patients compared with healthy and lesional controls. Our findings suggest that these proteins may be pathogenic, as well as possibly markers for diagnosis, disease severity and course. They may also prove to be useful therapeutic targets. More research is needed. [ABSTRACT FROM AUTHOR]

The skin is crucial for homeostasis and body defense, requiring quick healing to maintain internal balance. Initially used for bone repair, calcium hydroxyapatite (HAp) is now being studied for soft tissue engineering. This literature review investigated HAp's role in tissue repair through searches on PubMed, Scopus (Elsevier), Science Direct, Springer Link, and Google Scholar databases without time restrictions, using keywords "hydroxyapatite AND skin AND wound" and "hydroxyapatite AND skin repair". Inclusion criteria encompassed in vivo studies in humans and animals, English publications, full access, and sufficient data on HAp's role in tissue repair. Exclusions included duplicates, unrelated articles, editor letters, reviews, comments, conference abstracts, dissertations, and theses. Out of the 472 articles initially identified, 139 met the inclusion criteria, with 21 focusing on HAp for tissue repair. Findings indicate that HAp and nano-HAp in skin regeneration are promising, especially when combined with other biomaterials, offering antimicrobial and anti-inflammatory benefits and stimulating angiogenesis. This suggests their potential application in dermatology, surgery, and dentistry, extending HAp's versatility from hard tissues to enhancing critical properties for soft tissue repair and accelerating healing. [ABSTRACT FROM AUTHOR]

The present article addresses a novel mathematical model involving the Atangana-Baleanu (A-B) definition of fractional derivatives in time that offers a new interpretation of the thermo-mechanical effects inside skin tissue during thermal therapy. A Laplace transform mechanism is proposed to achieve closed-form solutions for prominent physical quantities, such as temperature, displacement, strain, and thermal stress. Computational results are obtained in time domains using an efficient numerical inversion algorithm of Laplace transform. The impact of the fractional parameter is investigated on the variations of the field quantities through the graphical results. The behavior of each physical field is speculated against the time parameter. The domain of influence of each field quantity is suppressed when the definition of the Atangana Baleanu fractional model is adopted, replicating that the waves under the A-B fractional model predict the finite nature of propagation compared to the conventional heat transport model. Further, we observe that the nature of the thermo-mechanical waves becomes stable earlier inside the tissue. [ABSTRACT FROM AUTHOR]

In this paper, the thermoviscoelastic response of skin tissue, as a typical class of viscoelastic biological tissue, subject to thermal shock is studied based on the fractional Kelvin-Voigt model and fractional Pennes bioheat conduction. A time-fractional biothermoviscoelastic governing equation is derived and initial-boundary value conditions are given for monolayer skin tissue of finite thickness. The temperature change and thermal stress of viscoelastic skin tissue are obtained by the Laplace transform and its inversion using matlab software. The influences of viscosity coefficient, relaxation times, fractional-order viscosity/heat parameter, and blood perfusion rate of skin tissue on the temperature distribution and the elastic displacement are analyzed. The numerical results show that fractional-order viscosity does not affect temperature, whereas fractional-order heat flow does. Moreover, fractional-order heat flow affects the sensitivity of blood perfusion rate to the thermodynamic response. [ABSTRACT FROM AUTHOR]

Scaffold porosity is a critical factor in replicating the complex in vivo microenvironment, directly influencing cellular interactions, migration, nutrient transfer, vascularization, and the formation of functional tissues. For optimal tissue formation, scaffold design must account for various parameters, including material composition, morphology, mechanical properties, and cellular compatibility. This review highlights the importance of interconnected porosity and pore size, emphasizing their impact on cellular behavior and tissue formation across several tissue engineering domains, such as skin, bone, cardiovascular, and lung tissues. Specific pore size ranges enhance scaffold functionality for different tissues: small pores (∼1–2 µm) aid epidermal cell attachment in skin regeneration, moderate pores (∼2–12 µm) support dermal migration, and larger pores (∼40–100 µm) facilitate vascular structures. For bone tissue engineering, multi-layered scaffolds with smaller pores (50–100 µm) foster cell attachment, while larger pores (200–400 µm) enhance nutrient diffusion and angiogenesis. Cardiovascular and lung tissues benefit from moderate pore sizes (∼25–60 µm) to balance cell integration and nutrient diffusion. By addressing critical design challenges and optimizing pore size distributions, this review provides insights into scaffold innovations, ultimately advancing tissue regeneration strategies.

In this paper, a new and more general model of heat conduction that depends on the drift velocity due to thermomass motion assumption will be established and will be applied to the skin tissue. Four different heat conduction models will be incorporated into a unified equation of heat conduction: the Pennes, Vernotte-Cattaneo, dual-phase-lag of Tzou, and the general two-temperature three-phase-lag of Youssef. The governing partial differential equations of the general two-temperature three-phase-lag model of bioheat conduction will be implemented and solved directly in the domain of the Laplace transformation. The numerical solutions of the Laplace transform will be calculated by executing the Tzou iteration formula. The ramp-type heat on the surface of the skin tissue will be considered as thermal loading. The conductive and dynamic temperature increment reactions have been studied and discussed with different values of ramp-time heat, characteristic length, and drift velocity parameters. The novelty of this work is to introduce some comparisons of the four under-studied bioheat conduction models and show the differences between them in the figures. The numerical results show that the ramp-time heat, drift velocity, and characteristic length parameters have major impacts on the increment of both dynamical and conductive temperature distributions.

Introduction: Changes in skin phenotypic characteristics are based on skin tissue. The study of the metabolic changes in skin tissue can help understand the causes of skin diseases and identify effective therapeutic interventions. Objectives: We aimed to establish and optimize a non-targeted skin metabolome extraction system for skin tissue metabolomics with high metabolite coverage, recovery, and reproducibility using gas chromatography/mass spectrometry. Methods: The metabolites in skin tissues were extracted using eleven different extraction systems, which were designed using reagents with different polarities based on sequential solid-liquid extraction employing a two-step strategy and analyzed using gas chromatograph/mass spectrometry. The extraction efficiency of diverse solvents was evaluated by coefficient of variation (CV), multivariate analysis, metabolites coverage, and relative peak area analysis. Results: We identified 119 metabolites and the metabolite profiles differed significantly between the eleven extraction systems. Metabolites with high abundances in the organic extraction systems, followed by aqueous extraction, were involved in the biosynthesis of unsaturated fatty acids, while metabolites with high abundances in the aqueous extraction systems, followed by organic extraction, were involved in amino sugar and nucleotide sugar metabolism, and glycerolipid metabolism. MeOH/chloroform-H2O and MeOH/H2O-chloroform were the extraction systems that yielded the highest number of metabolites, while MeOH/acetonitrile (ACN)-H2O and ACN/H2O-IPA exhibited superior metabolite recoveries. Conclusion: Our results demonstrated that our research facilitates the selection of an appropriate metabolite extraction approach based on the experimental purpose for the metabolomics study of skin tissue. [ABSTRACT FROM AUTHOR]

An effective procedure to explore the thermal response of living skin tissue exposed on severe thermal circumstance is proposed in this paper. The triple-layered inner structure with variable blood perfusion is employed to construct the governing equations via the dual-phase-lag model of bio-heat transfer. An analytical procedure, based on the Laplace transform and its limit theorem, is then introduced to the solution, in which a linearization technique is prior to disperse the non-linear terms included in these governing equations. The thermal response of the skin tissue with its boundary subjected to a pulse heat flux is solved and verified. A detailed parametric study has been carried out to evaluate the effect of the temperature dependency, phase lags, and material distribution on thermal response and associated thermal damage. [ABSTRACT FROM AUTHOR]

Epidermoid cysts are originated from entrapped ectodermal tissues at the fetal period or implanted epithelial tissue following trauma or inflammation. Although epidermoid cysts occur throughout the body, there have been only a few reports of epidermoid cysts originated from inserted skin tissue by interpositional arthroplasty for temporomandibular joint (TMJ) ankylosis. In this report, we show a rare case of epidermoid cyst considered as originated from abdominal skin tissue inserted into the TMJ 52 years ago. 63-year-old Japanese male presented with complain of swelling in the left buccal and subaural region. He had undergone two previous interpositional arthroplasties for TMJ ankylosis when he was 11 and 17 years old. Abdominal skin tissue had been inserted in the first surgery and a silicone sheet in the second surgery. CT revealed a 24 × 24 × 23 mm, well-marginated and round-shaped mass in the left region between mandibular ramus and parotid gland. The silicone sheet-like artifact was found in the left TMJ and partially contacted with the mass. MRI depicted the mass having the low signal in T1-weighted and the high signal on T2-weighted images. Needle biopsy detected the denucleated squamous cells. Therefore, the lesion was considered as dermoid or epidermoid cysts. Under general anesthesia, the mass was excised through the S-shaped skin incision from preauricular to subaural area and histopathologically diagnosed as an epidermoid cyst. It should be noted that epidermoid cysts could occur even long after skin tissue insertion which should be considered in diagnosis of the lesion arising around TMJ. [ABSTRACT FROM AUTHOR]

This article presents a mathematical analysis of thermoelastic skin tissue using an improved thermal conduction theory known as the refined three-phase-lag (TPL) theory. By accounting for the effects of multiple time derivatives, this advanced model provides a more accurate representation of how skin tissue behaves under different temperature conditions. The thin skin tissue is considered to have mechanically clamped surfaces, which are assumed to be one-dimensional. Furthermore, the skin tissue experiences a thermal shock load on its outer surface while maintaining a constant temperature on its inner surface. The proposed model has led to the derivation of certain generalized thermoelasticity theories in previous studies. The Laplace transform and its associated numerical inversion method are employed to calculate the distributions of temperature, displacement, dilatation, and stress in the system. The obtained outcomes are explicitly depicted to analyze the significant influences on the distributions of the field variables. These findings shed light on the behavior of skin tissue when subjected to a particular temperature distribution at the boundary condition, enhancing our knowledge in this area. [ABSTRACT FROM AUTHOR]

HY-072808 is a novel phosphodiesterase 4 inhibitor clinically used for topical atopic dermatitis treatment. Cytochrome P450 enzymes are involved in transforming it into major metabolite ZZ-24. An efficient UPLC–MS/MS method was established to detect HY-072808 and ZZ-24 in plasma and skin tissues of minipigs.One-step protein precipitation was performed with acetonitrile. Subsequently, elution was served with a methanol and water gradient containing 0.1% formic acid for 3.5 min. The plasma and skin tissue concentrations of HY-072808 and ZZ-24 showed good linearity from 0.200 to 200 ng/mL.The experimental minipigs exhibited low systemic exposure and bioavailability of 3.1–7.6% after transdermal application of 1–4% HY-072808 ointment. Multiple topical administrations over seven consecutive days showed a minor accumulation in systemic exposure, with accumulation factors of 2.3 and 4.0 for HY-072808 and ZZ-24, respectively.The distribution of HY-072808 ointment among different cortical layers in minipigs was studied for the first time. Following transdermal application of 2% HY-072808 ointment, the concentration in plasma and skin tissues in the order of epidermis > dermis > subcutaneous tissue ≈ subcutaneous muscle ≈ plasma; at 48 h after the administration, the epidermis and dermis still had a high concentration of the drug. [ABSTRACT FROM AUTHOR]

Background: Glabridin is one of the main components of the isoflavonoids in Glycyrrhiza glabra and possesses anti-inflammatory, anti-bacterial, and anti-cancer effects. Objectives: Herein, the therapeutic effects and mechanisms of action of the glabridin liposome (GL) complex were studied in mice with imiquimod-induced psoriasis. Materials and Methods: After treatment with GLs, their effectiveness was assessed using parameters, such as Psoriasis Area and Severity Index (PASI) score, histopathology, inflammatory cytokines, and psoriasis-associated proteins. Results: The results demonstrated that GLs could significantly improve psoriatic symptoms, downregulate mast cell infiltration, and significantly reduce the PASI score of psoriatic mice. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) results showed that GLs significantly decreased IL-23 and STAT3 mRNA expression. The results of immunohistochemistry and the enzyme-linked immunosorbent assay indicated that GLs decreased the expression of tumor necrosis factor-alpha (TNF-α), IL-17, and IL-22. Conclusion: GLs can alleviate psoriasis by inhibiting the expression of keratinocyte-activating proteins. These results suggest that GLs have great potential for the clinical treatment of psoriasis. [ABSTRACT FROM AUTHOR]

The spatial and temporal thermal response of skin and malignant tissues under the influence of microwave irradiation at different powers and frequencies is investigated using both the analytical and finite difference time domain methods. Given that the microwave heating process is highly dependent on the physical characteristics of the tissue; therefore, the temperature and frequency dependence of the tissue conductivity and permittivity are considered to estimate the temperature distribution inside the biological tissue for hyperthermia treatment. The results show how the appropriate microwave frequency range can be selected to enhance the hyperthermia efficiency. This study may open an avenue for obtaining appropriate microwave parameters for hyperthermia treatment. [ABSTRACT FROM AUTHOR]

In this study, we develop the heat conduction equation for bio-thermoelastic skin tissue with one relaxation time using Penne's principle, the first law of thermodynamics, and the second law of thermodynamics. We use these novel governing equations to explore the influence of arterial blood temperature on physical parameters in homogeneous, isotropic, thermally conducting half-space skin tissue. Normal mode analysis is applied in the domain to acquire analytical results for measured quantities. For a given skin tissue, these expressions are numerically calculated and graphically illustrated. The findings were predicted and tested for various values of arterial blood temperature. [ABSTRACT FROM AUTHOR]

3D‐printed scaffolds can better mimic the function of human skin, both biologically and mechanically. Within the scope of this study, the effect of the addition of different amounts (10, 15, 20 mg) of gentamicin sulfate (GS) to a 10 mL solution of natural and synthetic polymers is investigated. Sodium alginate (SA), gelatin‐methacryloyl (GelMA), and polyvinyl alcohol (PVA) are chosen as bioactive materials. The surface morphology and pore structures are visualized by scanning electron microscopy (SEM). According to the results, it is observed that the pore sizes of all scaffolds are smaller than 270 µm, the lowest value (130 µm) is obtained in the scaffold loaded with 15 mg GS, and it also has the highest tensile strength value (12.5 ± 7.6 MPa). Similarly, it is observed that the tensile strength (9.7 ± 4.5 MPa) is high in scaffold loaded with 20 mg GS. The biocompatibility test is performed with fibroblast cells, and the results show that the scaffolds are biocompatible with cells. The antibacterial test is carried out against the S.aureous and E. coli and the results indicate that all GS‐loaded scaffolds demonstrate antibacterial activity. [ABSTRACT FROM AUTHOR]

This study focuses on the analysis of the bio-thermoelasticity response exhibited by biological tissues when their inner and outer surfaces are free from stress and exposing the outer surface of the skin to harmonic heating with heatlessness of the inner surface of the skin. The investigation employs a refined Green-Lindsay model for a comprehensive understanding of the phenomenon. A system of partial differential equations is written and the solution is obtained using the Laplace transform and numerical inverse Laplace. The current model's results for temperature, displacement, stress, and strain distributions are presented, and it is compared to various (coupled and uncoupled) models from previous literature. The relaxation times effect on the model with other models is clarified, the effect of time, and some vital parameters are also studied, and tabularly to illustrate the effect of blood perfusion on the four distributions. [ABSTRACT FROM AUTHOR]

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In this paper, the effect of the femtosecond laser process parameters on the texture characteristics of the microstructure was analyzed with the response surface method. The correspondence between the temperature of skin during laser bonding and microscopic tissue texture characteristics parameters was explored. The results show that the three process parameters of laser power, scanning speed, and scanning times and the interaction between the parameters have different patterns of influence on the four texture characteristics parameters of skin microstructure angular second‐order moments, entropy, contrast, and relevance. Angular second‐order moments and relevance of skin microstructure textures increase with increasing temperature, while entropy values and contrast decrease. It provides another way to evaluate the performance of femtosecond laser‐bonded skin with microstructure. [ABSTRACT FROM AUTHOR]

Abstract 3D‐printed scaffolds can better mimic the function of human skin, both biologically and mechanically. Within the scope of this study, the effect of the addition of different amounts (10, 15, 20 mg) of gentamicin sulfate (GS) to a 10 mL solution of natural and synthetic polymers is investigated. Sodium alginate (SA), gelatin‐methacryloyl (GelMA), and polyvinyl alcohol (PVA) are chosen as bioactive materials. The surface morphology and pore structures are visualized by scanning electron microscopy (SEM). According to the results, it is observed that the pore sizes of all scaffolds are smaller than 270 µm, the lowest value (130 µm) is obtained in the scaffold loaded with 15 mg GS, and it also has the highest tensile strength value (12.5 ± 7.6 MPa). Similarly, it is observed that the tensile strength (9.7 ± 4.5 MPa) is high in scaffold loaded with 20 mg GS. The biocompatibility test is performed with fibroblast cells, and the results show that the scaffolds are biocompatible with cells. The antibacterial test is carried out against the S.aureous and E. coli and the results indicate that all GS‐loaded scaffolds demonstrate antibacterial activity.

Raman-active modes of human skin and pork belly have been studied systematically by a near-infrared Raman spectrometer with an exciting laser of 1064nm. The main components and quantitative determination of pork belly are extracted by fitting the Raman spectra with the normalized Raman spectra of biochemical reagents such as collagen, elastin, triolein, fibronectin, fibrin, and hyaluronic acid. It demonstrates that the main components and quantity are various at different locations of pork belly, while the main components of human skin are similar to those of pig skin. In a further step, the evolution of the heating time-dependent Raman modes of isolated pig skin has been investigated for the mechanism of burnt skin. One can find that the spatial structure and main components of skin have an excellent thermal stability in the temperature range from -120 to 200∘C, which is confirmed by the temperature dependent Raman spectra of isolated pig skin, microporous acellular dermal matrix (MADM) as well as their corresponding biochemical reagents (collagen, elastin, triolein, etc.). These results help understand the mechanism of the living skin burnt by fire or hot water, and supplies an alternative technology for surgeons to diagnose the depth of a burn injury in time.

This paper presents a new mathematical perfect of fractional order to deal with the response of skin tissue subjected to ramp-type heating based on the refined Lord--Shulman generalized thermoelasticity model. Three different models; the classical, the simple Lord--Shulman as well as the refined Lord--Shulman will be discussed. The governing equivalences of the present three models are attained. The general solution for the initial and boundary condition problem is found by employing the Laplace transform approach and its inverse. Numerical results are represented in figures with a comparison to the different theories with different values of fractional order to discuss the impact of the fractional order on temperature, displacement, and dilatation distributions. The effect of ramp-type heat is studied numerically and graphically on distributions of temperature, displacement, and dilatation according to different theories. [ABSTRACT FROM AUTHOR]

It has been well recognized that interactions between electromagnetic fields and metals are very strong. The consequence of human tissue in contact with metal, when subjected to an alternating electromagnetic field, is an increase in tissue temperature, which results from metals absorbing the energy obtained through induction. However, the electromagnetic induction characteristics and tissue energy absorbed caused by various electromagnetic field exposure conditions have not been well understood. A computational model was developed and employed in this study to assess the temporal and spatial temperature increases in skin due to contact with a highly conductive metallic plate while subjected to a high-intensity electromagnetic field. The effects of plate material, plate thickness, coil distance, and exposure time on temperature increase in the skin were computationally investigated. The electromagnetic and temperature distributions in skin layers during exposure to electromagnetic fields were achieved using models of electromagnetic wave propagation and an unsteady bioheat transfer. The modeling approach used indicates that the plate thickness, plate material, coil distance, and exposure time have a significant impact on the temperature change in the skin. The most important parameter was found to be the metal type. Iron has the greatest effect on skin temperature increase when subjected to external electromagnetic induction. These results allow the researchers to estimate more precisely the exposure limits for induction coils. [ABSTRACT FROM AUTHOR]

In India, rabies in cattle is under-reported. Religious sentiments hamper its diagnosis, discouraging post-mortem examination, particularly opening the cranium. Specimens of peripheral tissue innervated by the cranial nerves could potentially be used as alternative diagnostic specimens to the brain. Herein, we present a case study of a novel approach for diagnosing rabies in a cow suspected of having rabies, using skin tissue specimens of the nasolabial plate obtained post-mortem. Brain and nasolabial tissue specimens tested positive for rabies using conventional reverse-transcription polymerase chain reaction. This approach has been previously shown to have a high diagnostic sensitivity in animals. We encourage further studies with more nasolabial plate skin specimens for both post- and antemortem diagnosis of rabies in cattle. [ABSTRACT FROM AUTHOR]

The generalized thermo-viscoelastic theory without energy dissipation is used in this work to investigate the transfer of bioheat and the mechanical heat-induced response in a human skin plane tissue with variable thermal and rheological properties. Integral transformations are used for Laplace and Fourier. In the scheme of two-dimensional equations, the exponential matrix procedure, which forms the basis of the state-space approach of modern control theory, is applied. The resulting formulation is applied to a thermal shock half-space problem. The inversion process for Fourier and Laplace transforms is carried out using a numerical method based on Fourier series expansions. Comparisons between computational measurements and Penne's experimental verification indicate that the Green–Naghdi (II) bioheat mathematical model is an effective method for estimating the transition of bioheat to viscoelastic skin tissue. The influences of variable thermal conductivity and volume materials properties on all fields are examined. [ABSTRACT FROM AUTHOR]

Objective: In the present study, the effect of 2600 MHz radiofrequency radiation (RFR) exposure, and melatonin treatment on skin and liver tissue hydroxyproline (Hyp) levels were evaluated. Methods: In the study, 2600 MHz RFR application was performed by Rohde & Schwartz Radiofrequency signal generator via ETS-Lindgren horn antenna. 36 Wistar albino male rats were randomly divided into 6 groups (n = 6); Control, sham, RFR, control + Melatonin, Sham + Melatonin, RFR + Melatonin. RFR was applied to the related groups for 30 days (5 days/week) for 30 minutes a day. Average electric field value is 21.74 V / m. Melatonin groups were subcutaneously injected with melatonin (10 mg/kg) for 30 days. At the end of the experiment, Hyp levels were measured in the skin and liver tissues. Results: Hyp levels in skin tissue decreased significantly in RFR treated groups compared to the control and sham groups (p <0.05). Also, Hyp levels in skin tissue decreased significantly in RFR + melatonin treated group compared to the control, sham and sham+melatonin groups. No changes in Hyp levels in liver tissue were determined. Conclusion: In this study, RFR exposure leads to significant changes in skin Hyp levels but not liver tissue. This effect is thought to be due to the closer the skin tissue to the surface. [ABSTRACT FROM AUTHOR]

In this article, a mathematical analysis of thermoelastic skin tissue is presented based on a refined dual-phase-lag (DPL) thermal conduction theory that considers accounting for the effect of multiple time derivatives. The thin skin tissue is regarded as having mechanically clamped surfaces that are one-dimensional. Additionally, the skin tissue undergoes ramp-type heating on its outer surface, whereas its inner surface keeps the assessed temperature from vanishing. Some of the previous generalized thermoelasticity theories were obtained from the proposed model. The distributions of temperature, displacement, dilatation, and stress are attained by applying the Laplace transform and its numerical reversal approaches. The outcomes are explicitly illustrated to examine the significant influences on the distributions of the field variables. The refined DPL bioheat conduction model in this study predicts temperature, and the findings revealed that the model is located among the existing generalized thermoelastic theories. These findings offer a more thorough understanding of how skin tissue behaves when exposed to a particular boundary condition temperature distribution. [ABSTRACT FROM AUTHOR]

Based on Green–Lindsay generalized thermoelasticity theory, this paper presents a new refined higher-order time-derivative thermoelasticity model. Thinner one-dimensional skin tissue is considered when its inner surface is free of traction and does not show any temperature increase. The skin tissue's bounding surface has been heated by ramp-type heating. The classical thermoelastic theories are obtained from the present general formula. The governing equations of the present model are obtained. To move the system into a space state, the Laplace transform is used. The inverse of the Laplace transform is also used with Tzuo's method to solve the problem. As a result, the field quantities are obtained numerically, and the results of the current model are graphically represented with a comparison to two different theories of thermoelasticity. The effects of various parameters on thermomechanical waves through the skin tissue are analyzed. The theory notes a vibrational behavior in heat transfer and a different effect on the parameters discussed in this article. [ABSTRACT FROM AUTHOR]

Circular RNA (circRNA) is a type of non-coding RNA generated from back-splicing the reactions of linear RNA. It plays an important role in various cellular and biological processes. However, there are few studies about the regulatory effect of circRNAs on cashmere fiber traits in cashmere goats. In this study, the expression profiles of circRNAs in skin tissue were compared between Liaoning cashmere (LC) goats and Ziwuling black (ZB) goats, with a significant difference in cashmere fiber yield, cashmere fiber diameter, and cashmere fiber color, using RNA-seq. A total of 11,613 circRNAs were expressed in the caprine skin tissue, and their type, chromosomal distribution, and length distribution were characterized. A total of 115 up-regulated circRNAs and 146 down-regulated circRNAs in LC goats were screened compared to ZB goats. The authenticity of 10 differentially expressed circRNAs was validated by detecting their expression levels and the head-to-tail splice junction using RT-PCR and DNA sequencing, respectively. The parent genes of differentially expressed circRNA were mainly enriched in some Gene Ontology (GO) terms and pathways related to cashmere fiber traits, such as the canonical Wnt signaling pathway, which is involved in the regulation of cell promotion, stem cell proliferation, Wnt signaling pathway regulation, epithelial morphogenesis, MAPK signaling pathway, and cell adhesion molecules pathway. Eight differentially expressed circRNAs were further selected to construct a circRNA-miRNA network, and some miRNAs that were previously reported as related to fiber traits were found in the network. This study provides a deep understanding of the roles of circRNAs in the regulation of cashmere fiber traits in cashmere goats and the involvement of differential splicing in phenotypic expression according to breed and region. [ABSTRACT FROM AUTHOR]

Circular RNAs (circRNAs) were identified as noncoding RNAs with covalently closed structures differing from other types of RNA molecules. It was thought that circRNAs were implicated in the development of secondary hair follicles (SHFs) of cashmere goats. In this investigation, a total of 21 novel circRNAs were identified from the skin tissue of cashmere goats. Of them, nine circRNAs were found to be significantly higher in expression at anagen skin tissue than those at telogen of cashmere goats. Based on bioinformatics analysis, a complicated regulatory relationship was revealed among the nine upregulated circRNAs at anagen with related signalling pathways, such as Wnt signalling pathway, TGF-beta signalling pathway, mTOR signalling pathway, MAPK signalling pathway, and axon guidance. Further, the expression pattern analysis of the nine upregulated circRNAs at anagen along with their host genes in SHFs suggested their potential functional roles in the regeneration and growth of anagen SHFs of cashmere goats. Our results provided novel significant information for elucidating the molecular regulatory mechanisms understanding the regeneration and growth of SHFs in cashmere goats, which will be essential for artificially regulating the growth of cashmere to increase cashmere yield.

In this study, we introduce a three-phase-lag (TPL) bioheat transfer model for living biological tissue by considering the heat conduction law that includes heat flux, temperature gradient and thermal displacement gradient, among the constitutive relation. The formulated TPL bioheat model is an extension of bioheat transfer models proposed by Pennes, Cattaneo-Vernotte and Tzou. The semi-analytical method has been used for the solution of TPL bioheat transfer model and this model is validated with experimental data [Stolwijk, J. A. J., and J. D. Hardy. 1966. Temperature regulation in man: a theoretical study. Pflugers Archiv Fur Die Gesamte Physiologie Des Menschen Und Der Tiere 291(2):129–62]. The phase lag times due to heat flux, temperature gradient and thermal displacement gradient is semi analytically investigated and it is found that phase-lag due to thermal displacement gradient affects significantly on temperature distribution in tissue. The semi-analytical solution has been verified with a numerical solution. The effect of parameters, such as lagging times, blood perfusion rate, metabolic heat source term and TPL parameter on tissue temperature is also discussed in detail. Three-phase-lag bioheat transfer model has been introduced for the study of heat transfer in living biological tissue. The semi analytical method has been used for the solution of the TPL model. Proposed model is validated with experimental data. The formulated TPL model is more accurate than other existing models. [ABSTRACT FROM AUTHOR]

In this retrospective study, the understanding of heat transport and temperature variations on the tissues of the patients with recurrent cervical cancer subjected to chemoradiation or neoadjuvant chemotherapy followed by surgery and radiotherapy has been studied in the light of Caputo–Fabrizio (CF) bio-heat transport law, in the context of Lord–Shulman (LS) model. The skin tissue is subjected to prescribed temperature and both ends of the tissue are thermally insulated. Laplace transform technique is implemented to solve the governing equations. The influences of CF order and moving heat source velocity on the temperature of skin tissues and the thermal injuries are precisely investigated. The thermal injuries to the tissue are assessed by the denatured protein range using the current formulation in which the numerical inversion of the Laplace transform is carried out using Zakian methods. The numerical outcomes of thermal injuries and temperatures have been represented graphically. Excellent predictive capability is demonstrated for identification of appropriate procedure to select different orders of CF derivative to reach effective heating in hyperthermia treatment. [ABSTRACT FROM AUTHOR]

Histopathological diagnosis involves examination of slides stained by chemical stains which are health hazard to researchers, technicians and pathologists. This study screened plant based natural stains for histological applications. About 176 test staining solutions were prepared from 11 plant extracts and the staining ability in rat skin tissue was compared with the routinely used Hematoxylin and Eosin (H&E) stain. Punica granulatum, Bixa orellana, Termanalia chebula, Rheum emodi, Rubia tinctorium, Beta vulgaris, Lawsonia inermis, and Tagetes erecta extracts showed more staining intensity. This is the first study to demonstrate the staining ability of Termanalia chebula, Rheum emodi, and Tagetes erecta in biological tissue. Among all plants, Rubia tinctorium and Beta vulgaris showed better staining ability, but lower than H&E. By modifying the concentration, pH, and staining time, we could get better natural stains for histology. [ABSTRACT FROM AUTHOR]

The irregular shape and depth of wounds could be the major hurdles in wound healing for the common three-dimensional foam, sheet, or film treatment design. The injectable hydrogel is a splendid alternate technique to enhance healing efficiency post-implantation via injectable or 3D-bioprinting technologies. The authentic combination of natural and synthetic polymers could potentially enhance the injectability and biocompatibility properties. Thus, the purpose of this study was to characterise a hybrid gelatin–PVA hydrogel crosslinked with genipin (GNP; natural crosslinker). In brief, gelatin (GE) and PVA were prepared in various concentrations (w/v): GE, GPVA3 (3% PVA), and GPVA5 (5% PVA), followed by a 0.1% (w/v) genipin (GNP) crosslink, to achieve polymerisation in three minutes. The physicochemical and biocompatibility properties were further evaluated. GPVA3_GNP and GPVA5_GNP with GNP demonstrated excellent physicochemical properties compared to GE_GNP and non-crosslinked hydrogels. GPVA5_GNP significantly displayed the optimum swelling ratio (621.1 ± 93.18%) and excellent hydrophilicity (38.51 ± 2.58°). In addition, GPVA5_GNP showed an optimum biodegradation rate (0.02 ± 0.005 mg/h) and the highest mechanical strength with the highest compression modulus (2.14 ± 0.06 MPa). In addition, the surface and cross-sectional view for scanning electron microscopy (SEM) displayed that all of the GPVA hydrogels have optimum average pore sizes (100–199 μm) with interconnected pores. There were no substantial changes in chemical analysis, including FTIR, XRD, and EDX, after PVA and GNP intervention. Furthermore, GPVA hydrogels influenced the cell biocompatibility, which successfully indicated >85% of cell viability. In conclusion, gelatin–PVA hydrogels crosslinked with GNP were proven to have excellent physicochemical, mechanical, and biocompatibility properties, as required for potential bioinks for chronic wound healing. [ABSTRACT FROM AUTHOR]

Scaffold porosity is a critical factor in replicating the complex in vivo microenvironment, directly influencing cellular interactions, migration, nutrient transfer, vascularization, and the formation of functional tissues. For optimal tissue formation, scaffold design must account for various parameters, including material composition, morphology, mechanical properties, and cellular compatibility. This review highlights the importance of interconnected porosity and pore size, emphasizing their impact on cellular behavior and tissue formation across several tissue engineering domains, such as skin, bone, cardiovascular, and lung tissues. Specific pore size ranges enhance scaffold functionality for different tissues: small pores (∼1-2 µm) aid epidermal cell attachment in skin regeneration, moderate pores (∼2-12 µm) support dermal migration, and larger pores (∼40-100 µm) facilitate vascular structures. For bone tissue engineering, multi-layered scaffolds with smaller pores (50-100 µm) foster cell attachment, while larger pores (200-400 µm) enhance nutrient diffusion and angiogenesis. Cardiovascular and lung tissues benefit from moderate pore sizes (∼25-60 µm) to balance cell integration and nutrient diffusion. By addressing critical design challenges and optimizing pore size distributions, this review provides insights into scaffold innovations, ultimately advancing tissue regeneration strategies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Mukasheva, Adilova, Dyussenbinov, Yernaimanova, Abilev and Akilbekova.)

In this paper, a new and more general model of heat conduction that depends on the drift velocity due to thermomass motion assumption will be established and will be applied to the skin tissue. Four different heat conduction models will be incorporated into a unified equation of heat conduction: the Pennes, Vernotte-Cattaneo, dual-phase-lag of Tzou, and the general two-temperature three-phase-lag of Youssef. The governing partial differential equations of the general two-temperature three-phase-lag model of bioheat conduction will be implemented and solved directly in the domain of the Laplace transformation. The numerical solutions of the Laplace transform will be calculated by executing the Tzou iteration formula. The ramp-type heat on the surface of the skin tissue will be considered as thermal loading. The conductive and dynamic temperature increment reactions have been studied and discussed with different values of ramp-time heat, characteristic length, and drift velocity parameters. The novelty of this work is to introduce some comparisons of the four under-studied bioheat conduction models and show the differences between them in the figures. The numerical results show that the ramp-time heat, drift velocity, and characteristic length parameters have major impacts on the increment of both dynamical and conductive temperature distributions., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 Published by Elsevier Ltd.)

It has been well recognized that interactions between electromagnetic fields and metals are very strong. The consequence of human tissue in contact with metal, when subjected to an alternating electromagnetic field, is an increase in tissue temperature, which results from metals absorbing the energy obtained through induction. However, the electromagnetic induction characteristics and tissue energy absorbed caused by various electromagnetic field exposure conditions have not been well understood. A computational model was developed and employed in this study to assess the temporal and spatial temperature increases in skin due to contact with a highly conductive metallic plate while subjected to a high-intensity electromagnetic field. The effects of plate material, plate thickness, coil distance, and exposure time on temperature increase in the skin were computationally investigated. The electromagnetic and temperature distributions in skin layers during exposure to electromagnetic fields were achieved using models of electromagnetic wave propagation and an unsteady bioheat transfer. The modeling approach used indicates that the plate thickness, plate material, coil distance, and exposure time have a significant impact on the temperature change in the skin. The most important parameter was found to be the metal type. Iron has the greatest effect on skin temperature increase when subjected to external electromagnetic induction. These results allow the researchers to estimate more precisely the exposure limits for induction coils.

In this article, we present a mathematical model of thermoelastic skin tissue based on a refined Lord–Shulman heat conduction theory. A small thickness of skin tissue is considered to be one-dimensional with mechanical clamped surfaces. In addition, the skin tissue's outer surface is subjected to ramp-type heating while its inner surface is adiabatic. A simple Lord–Shulman theory, as well as the classical coupled thermoelasticity, are also applied in this article. Laplace transform techniques and their inversions are calculated to return to the time domain. Numerical outcomes are represented graphically to discuss the significant impacts on the temperature, dilatation, displacement, and stress distributions. Such results provide a more comprehensive and better insight for understanding the behavior of skin tissue during the temperature distribution of a specific boundary condition. [ABSTRACT FROM AUTHOR]

The evolution of thermal response in the biological tissue is very important to the effective medical treatment processes. The purpose of this work is to seek an analytical method to solve the transient bio-heat transfer problem. The governing equations with the pulse boundary heat flux on skin tissue are first proposed in the context of the dual-phase-lag model (DPL model). An analytical procedure, based on Laplace transform technique and its limit theorem, is then introduced to solve these equations analytically. The exact solution of the temperature distribution is finally obtained and is used to reveal the temporal and spatial effects on the transient heat transfer through skin tissues. The thermal damage is further studied and some evaluation is also conducted by comparing with the results from the classical Pennes model of bio-heat transfer (PMBHT). [ABSTRACT FROM AUTHOR]

The present paper reports a magnesium oxide (MgO) nanoparticle incorporated carboxy methyl cellulose (CMC)/poly vinyl alcohol (PVA) composite film with favorable composition for skin tissue engineering application. CMC/PVA films were prepared with different polymer ratios and cross linked with glutaraldehyde. The films possess surface roughness favorable for cell adhesion, desired swelling behavior and controlled degradation. Among the films, CMC/PVA (50:50) have tensile strength (28.31 MPa) and hydrophilicity (69.8º contact angle) close to those of skin tissue. MgO nanoparticles was incorporated in CMC/PVA film to improve antimicrobial and cell supportive property. The MTT assay revealed that MgO–incorporated composite films were non-cytotoxic exhibiting higher cell viability which is favorable for cell proliferation. CMC/PVA films with 1.5% PVA showed higher cell viability than other composite films with desired antimicrobial property. Thus, CMC/PVA composite film containing 1.5% MgO was demonstrated to be a potential artificial extra cellular matrix for skin tissue engineering application. [ABSTRACT FROM AUTHOR]

An analytical solution of the three-dimensional transient temperature distribution for skin tissue when heated by a laser heat source is presented in this work. An equation for the three-dimensional bioheat transfer of skin tissue is obtained firstly, and the transient temperature value at any point inside the skin tissue can be solved using the separation variable method and the Newton-Cotes method. Previous research primarily focused on semi-infinite domains, while this work presents an analytical solution for finite domains. A comparison of present analytical solution with simulation software results and numerical solution is given to demonstrate the feasibility of the analytical solution. The three-dimensional temperature distribution of skin tissue irradiated by a laser is theoretically studied. The extent of thermal damage to skin tissue is assessed by substituting the analytical solution of the temperature field for laser-irradiated skin tissue into the thermal damage equation. The calculations in this work reveal that the variation of temperature field in biological tissues is dependent not only on the laser incident light intensity and the optical parameters of the tissues but also on the heat transfer properties of the biological tissues, such as the blood perfusion rates. [ABSTRACT FROM AUTHOR]