Facial Skin Tissue Research Articles

Analysis of optical absorption of photoaged human skin using a high-frequency illumination microscopy analysis system.

Skin is composed of different layers, including the stratum corneum, epidermal living layer and papillary and reticular dermis. Each has specific optical properties due to differences in their biological components. Alterations in the skin's cutaneous biological components resulting from photoaging caused by chronic exposure to UV light affect the deterioration of appearance associated with the skin's optical properties. Various methods for analysing cutaneous optical properties have been previously proposed, including mathematical models and computer simulations. However, these were insufficient to elucidate changes in each skin layer and comprehensively understand the skin's integrated optical properties. We focused on UV-induced yellowing of the facial skin. We evaluated site-specific optical absorption of human skin tissue sections to investigate the yellowish discoloration, which is suggested to be related to the photodamage process. The method includes our original technique of separating the transmitted and scattered light using high-frequency illumination microscopy, leading to microscopic analysis of the tissue's optical absorption in the regions of interest. In analysing the sun-exposed facial skin tissue sections, we successfully showed that dermal regions of aged skin have increased absorption at 450 nm, where yellowish colours are complemented. Furthermore, we confirmed that elastic fibres with observable histological disorder resulting from photodamage are a prominent source of high optical absorption. We detected changes in the skin's optical absorption associated with dermal degeneration resulting from photodamage using a novel optical microscopy technique. The results provide a base for the evaluation of optical property changes for both yellowing discoloration and other tissue disorders.

Effect of pdo facelift threads on facial skin tissues: An ultrasonographic analysis.

Recent studies demonstrate that PDO threads, after being introduced into the facial skin, provide benefits due to collagen formation around the thread and improved vascularization. This work aims to report the ultrasound and photographic follow-up after the execution of the facelift thread technique, thus evaluating the anti-aging treatment that PDO threads will provide for human facial skin. The facelift will be performed using PDO thread 18G cannulated Sculpt i- Thread FML 100 × 185 mm, and 29G PDO thread Needled Flat i-Thread 38 × 50 mm. A total of 10 patients were selected for the study; all of them had medium-grade facial ptosis and aged 40-50 years old. In order to control tissue changes after thread, insertion ultrasound measurements will be made with Philips ultrasound 12 MHz linear probe at maximum resolution, initial evaluations and control of 30, 60, 90, and 120 days, measuring the skin layers: epidermis\dermis and hypodermis. Photographic control was performed before and after 120 days of intrusion of the PDO threads. The formation of collagen around the PDO thread was evidenced through ultrasound images in all patients in this study, as well as improvement in the appearance of the skin and sagging, evaluated by photographic control. We can define that the PDO threads used for the facelift are effective in the formation of collagen around the thread (observed through the increase in the dermal layer), and improvement of the condition of the anti-aging factor through sagging skin, vascularization and thinning of the superficial fat layer (observed through the reduction of the subcutaneous or hypodermis layer).

Cytotoxicity Evaluation on Clean Grade Silicone Reinforced with Nanosilica Filler as an Alternative Maxillofacial Prosthesis

Maxillofacial prosthesis is a non-invasive procedure to replace damaged or lost facial tissue structures. Extraoral maxillofacial prosthesis to resemble facial skin tissue is made of silicone. The addition of fillers and pigments to silicone has been done to improve its physical and mechanical properties while maintaining its biocompatibility. This study aims to evaluate the cytotoxicity of nano silica filler and intrinsic pigment additives in clean grade silicone as an alternative material for maxillofacial prosthesis. Thirty clean grade silicone samples were divided into 6 treatment groups: 1 group of silicone without any additives and 5 groups of silicone with addition of intrinsic pigment and nano silica filler with concentration of 0%, 1%, 2%, 3% and 6%. Cytotoxicity was assessed by MTT assay against 3T3L1 fibroblasts. The average absorbance value for all treatment groups was 0,941-1,105, which was lower than the control group. The post hoc test showed that only the 6% of nano silica and intrinsic pigment additive group did not differ from the control group. The addition of silica nano filler and intrinsic pigment to silicone did not cause toxicity to 3T3L1 cells. The cytotoxicity of nano silica is determined by its particle size and concentration. The use of intrinsic pigments produces compounds that are less reactive to genetic material. In conclusion, the addition of nano silica filler and intrinsic pigment to clean grade silicone as an alternative maxillofacial prosthesis is nontoxic. The addition of 6% nano silica filler and intrinsic pigment to clean grade silicone showed the best cell viability.

Contactless Heart Rate Measurement System Based RGB Camera, Cascade Object Detector and Independent Component Analysis

This paper focuses on the development of non-contact heart rate measurement based on video analysis. This project implements an RGB camera (OV2640 with ESP32 Cam) and an FTDI Programmer which enables the sensor to record videos from a subject at a distance of 20 cm. The Region of Interest (ROI) of the facial skin tissue was detected by using Cascade Object Detector (COD) which can detect object categories whose aspect ratio does not vary significantly. Then, the Independent Component Analysis (ICA) was applied by extracting distinct source signals (red, blue and green channels) from the observed mixed colour signals. Next, the average pixel of ROI was calculated based on red, green and blue facial pixel at given time. Finally, the heart rate was extracted from the frequency spectrum of the average pixel. The performance of the developed contactless system was compared with the fingertip pulse oximeter (Oxitech) by means of percentage of error (PE). The lowest range of PE is between 0 to 5.62 % whereas the highest PE is 22.54 %. The highest error was due to incorrectly captured ROI of facial skin area as well as due to the movement made during the recording session. Meanwhile, the average time for the developed system to process the heart rate of the subject is 4.51 minutes. In future, a robust ROI algorithm can be adopted to reduce error contributed by incorrectly ROI selection. Other than that, this project has a potential to contribute to the area of contactless measurement of oxygen saturation.

Robotics Meets Cosmetic Dermatology: Development of a Novel Vision-Guided System for Skin Photo-Rejuvenation

In this article, we present a novel robotic system for skin photo-rejuvenation, which uniformly delivers laser thermal stimulation to a subject’s facial skin tissue. The robotized treatment is performed by a customized manipulator instrumented with a cosmetic laser generator, a depth sensor, and a thermal camera. To plan the optimal trajectory of the manipulator, our system computes the surface model of the face and segments it into seven regions, then automatically fills these regions with uniform laser irradiation. Finally, we report the detailed results of experiments on multiple human subjects to validate the performance of the system. To the best of the author’s knowledge, this is the first time that facial skin rejuvenation has been automated by robot manipulators.

Spatiotemporal monitoring of changes in oxy/deoxy-hemoglobin concentration and blood pulsation on human skin using smartphone-enabled remote multispectral photoplethysmography.

We propose a smartphone-enabled remote multispectral photoplethysmography (SP-rmPPG) system and method to realize spatiotemporal monitoring of perfusion changes and pulsations of the oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb) information of the effective blood volume within light interrogated skin tissue beds. The system is implemented on an unmodified smartphone utilizing its built-in camera and flashlight to acquire videos of the skin reflectance. The SP-rmPPG method converts the RGB video into multispectral cubes, upon which to decouple the dynamic changes in HbO2 and Hb information using a modified Beer-Lambert law and the selective wavelength bands of 500 nm and 650 nm. Blood pulsation amplitudes are then obtained by applying a window-based lock-in amplification on the derived spatiotemporal changes in HbO2 or Hb signals. To demonstrate the feasibility of proposed method, we conduct two experiments on the skin tissue beds that are conditioned by occlusive maneuver of supplying arteries: one using the popular blood cuff pressure maneuver on the upper arm, and another artificially inducing a transient ischemic condition on the facial skin tissue beds by finger pressing on the supplying external carotid artery. The cuff experiment shows that the measured dynamic information of HbO2 and Hb in the downstream agrees well with the parallel measurements of oxygenation saturation given by the standard pulse oximeter. We also observe the expected imbalance of spatiotemporal changes in the HbO2 and Hb between the right and left cheeks when the transient ischemic condition is induced in the one side of facial skin tissue beds. The results from the two experiments sufficiently demonstrate the feasibility of the proposed method to monitor the spatiotemporal changes in the skin hemodynamics, including blood oxygenation and pulsation amplitudes. Considering the ever-growing accessibility and affordability of the smartphone to the general public, the proposed strategy promises the early screening of vascular diseases and improving general public health particularly in rural areas with low resource settings.

A Segmentation Enhancement Method for the Low-Contrast and Narrow-Banded Substances in CBCT Images

Due to its low contrast, narrow banded, and emerged to the output imaging attribute scale, facial skin tissue is difficult to extract from dental cone-beam computed tomography (CBCT) reconstructions. Furthermore, there is a challenge of balancing the indication and patient-specific factors and imaging dosage to make it both safe and diagnostically effective for successful treatment planning. These issues make a new frontier for facial skin and soft tissue diagnostic applications driven by sparse dental and low-dose CBCT data. In this study, a new segmentation enhancement method for low-contrast and narrow-banded substances is proposed based on our previous work on selective anatomy analysis iterative reconstruction (SA2IR). The purpose of the proposed method is to segment facial skin tissue based on combinatorial optimization and previously known facial soft tissue structure anatomy. Our results using this method indicated that the skin thickness was much more easily and more quickly identified than with conventional ultrasonic scanning methods. This method holds the potential to be an assisting tool for studying linage of anthropometrics, forensics, human archaeology, and some narrow medico-dental applications.

Substance P receptor blocker, aprepitant, inhibited cutaneous and other neurogenic inflammation side effects of the EGFR1-TKI, erlotinib.

Cutaneous changes like rash and hair loss, as well as other neurogenic inflammation side effects, occur frequently during anticancer treatment with the epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), erlotinib. These adverse events may be so severe that they impair the patient's compliance with the treatment or even cause its discontinuation. In the current preclinical study, rats (9.2weeks) were treated with erlotinib (10mg/kg/day) ± aprepitant (2mg/kg/day) for 12weeks. Visual changes in the development of facial skin lesions/hair loss and SP-receptor expression (immunohistochemically) in facial skin tissue were assessed; also changes in plasma magnesium, 8-isoprostane, substance P (SP), neutrophil superoxide production, and cardiac function (echocardiography) were measured. Erlotinib lowered plasma magnesium 14%, elevated SP 65%, caused 3.7-fold higher basal superoxide production, 2.5-fold higher 8-isoprostane levels, 11.6% lower cardiac systolic, and 10.9% lower diastolic function. Facial dermatological changes (alopecia, skin reddening, scabbing, nose crusting) occurred by 4weeks (± + to ++) in erlotinib-treated rats, and progressively worsened (±++ to +++) by week 12. Facial skin SP-receptor upregulation (78% higher) occurred in epidermal and hair follicle cells. All adverse effects were substantially and significantly mitigated by aprepitant, including a 62% lowering of skin SP-receptors (p < 0.05). Elevated SP levels mediated the side effects of erlotinib treatment, but aprepitant's significant prevention of the systemic and cutaneous adverse events indicates a novel potential therapy against the side effects of this anticancer treatment.

An open-source remote heart rate imaging method with practical apparatus and algorithms

Recent developments in computer science and digital image processing have enabled the extraction of an individual’s heart pulsations from pixel changes in recorded video images of human skin surfaces. This method is termed remote photoplethysmography (rPPG) and can be achieved with consumer-level cameras (e.g., a webcam or mobile camera). The goal of the present publication is two-fold. First, we aim to organize future rPPG software developments in a tractable and nontechnical manner, such that the public gains access to a basic open-source rPPG code, comes to understand its utility, and can follow its most recent progressions. The second goal is to investigate rPPG’s accuracy in detecting heart rates from the skin surfaces of several body parts after physical exercise and under ambient lighting conditions with a consumer-level camera. We report that rPPG is highly accurate when the camera is aimed at facial skin tissue, but that the heart rate recordings from wrist regions are less reliable, and recordings from the calves are unreliable. Facial rPPG remained accurate despite the high heart rates after exercise. The proposed research procedures and the experimental findings provide guidelines for future studies on rPPG.

Effect of Humidified Noninvasive Ventilation on the Development of Facial Skin Breakdown.

The use of noninvasive ventilation masks is known to cause damage to facial skin tissue, which affects both the efficacy of the intervention and the patient's quality of life. The use of humidification with noninvasive ventilation is a common practice, but its relative role in the development of facial pressure ulcers has not been fully studied. A crossover cohort design was used in this study, with 15 healthy volunteers. Each volunteer randomly received both 10 cm H2O of CPAP with and without humidification through an oronasal mask. Skin integrity was evaluated by measuring transepidermal water loss, skin hydration, and skin pH at the bridge of the nose. Device-skin interface conditions (pressure and microclimate) were recorded at the bridge of the nose and both cheeks. The pro-inflammatory cytokine interleukin-1α was collected from the nose bridge before and after CPAP application by using a skin analysis tape. Nasal symptoms were collected by using a validated 6-point score. Humidified CPAP significantly increased transepidermal water loss (P < .001) and skin humidity (P = .02) compared with non-humidified CPAP. There were no significant differences in skin hydration, skin pH, skin temperature, and cytokine expression between both conditions. However, there was a trend of increased median ratios of interleukin-1α concentrations in the humidified CPAP. There was a significant increase in the interface pressure at the bridge of the nose after CPAP application (P = .02), with higher interface pressure values at the nose bridge compared with both left (P = .002) and right (P = .003) cheeks. The participants reported elevated nasal discomfort during non-humidified CPAP. These findings indicated that noninvasive ventilation with humidification had a potential disrupting effect on the barrier function of facial skin, associated with changes in skin microclimate and function. Further research is required to establish the cause of mask-related skin damage and to evaluate the effects of mask design, application techniques, and air flow and humidity settings.

Elastic-viscoplastic modeling of soft biological tissues using a mixed finite element formulation based on the relative deformation gradient.

The characteristic highly nonlinear, time-dependent, and often inelastic material response of soft biological tissues can be expressed in a set of elastic-viscoplastic constitutive equations. The specific elastic-viscoplastic model for soft tissues proposed by Rubin and Bodner (2002) is generalized with respect to the constitutive equations for the scalar quantity of the rate of inelasticity and the hardening parameter in order to represent a general framework for elastic-viscoplastic models. A strongly objective integration scheme and a new mixed finite element formulation were developed based on the introduction of the relative deformation gradient-the deformation mapping between the last converged and current configurations. The numerical implementation of both the generalized framework and the specific Rubin and Bodner model is presented. As an example of a challenging application of the new model equations, the mechanical response of facial skin tissue is characterized through an experimental campaign based on the suction method. The measurement data are used for the identification of a suitable set of model parameters that well represents the experimentally observed tissue behavior. Two different measurement protocols were defined to address specific tissue properties with respect to the instantaneous tissue response, inelasticity, and tissue recovery.

Automatic expression spotting in videos

In this paper, we propose a novel solution for the problem of segmenting macro- and micro-expression frames (or retrieving the expression intervals) in video sequences, which is a prior step for many expression recognition algorithms. The proposed method exploits the non-rigid facial motion that occurs during facial expressions by capturing the optical strain corresponding to the elastic deformation of facial skin tissue. The method is capable of spotting both macro-expressions which are typically associated with expressed emotions and rapid micro- expressions which are typically associated with semi-suppressed macro-expressions. We test our algorithm on several datasets, including a newly released hour-long video with two subjects recorded in a natural setting that includes spontaneous facial expressions. We also report results on a dataset that contains 75 feigned macro-expressions and 37 feigned micro-expressions. We achieve over a 75% true positive rate with a 1% false positive rate for macro-expressions, and a nearly 80% true positive rate for spotting micro-expressions with a .3% false positive rate.

High-resolution 3D surface strain magnitude using 2D camera and low-resolution depth sensor

Generating 2-D strain maps of the face during facial expressions provides a useful feature that captures the bio-mechanics of facial skin tissue, and has had wide application in several research areas. However, most applications have been restricted to collecting data on a single pose. Moreover, methods that strictly use 2-D images for motion estimation can potentially suppress large strains because of projective distortions caused by the curvature of the face. This paper proposes a method that allows estimation of 3-D surface strain using a low-resolution depth sensor. The algorithm consists of automatically aligning a rough approximation of a 3-D surface with an external high resolution camera image. We provide experimental results that demonstrate the robustness of the method on a dataset collected using the Microsoft Kinect synchronized with two external high resolution cameras, as well as 101 subjects from a publicly available 3-D facial expression video database (BU4DFE).

Increased expression of cathelicidin by direct activation of protease-activated receptor 2: possible implications on the pathogenesis of rosacea.

PurposeRecent findings of increased cathelicidin protein and its proteolytic fragments in rosacea suggest a pathogenic role for cathelicidin in this disease. The relationship between cathelicidin and protease-activated receptor 2 (PAR-2) is therefore of interest, as PAR-2, expressed principally in keratinocytes, regulates pro-inflammatory cytokine expression in the skin. The purpose of this study was to determine the relationship between expression of PAR-2 and cathelicidin in rosacea and to test the effect of direct PAR-2 activation on cathelicidin expression in keratinocytes.Materials and MethodsSamples from 40 patients with clinicopathologic diagnosis of rosacea and facial skin tissue samples from 20 patients with no specific findings or milium without inflammation were retrieved. Intensities of immunohistochemical staining for PAR-2 and cathelicidin were compared between normal and rosacea-affected skin tissues. Additionally, correlations between PAR-2 and cathelicidin staining intensities within rosacea patients were analyzed. In cultured keratinocytes, changes in PAR-2, cathelicidin, and vascular endothelial growth factor (VEGF) mRNA and protein were analyzed after treatment with PAR-2 activating peptide (AP).ResultsCathelicidin expression was significantly higher in rosacea skin tissues than in normal tissues (p<0.001), while PAR-2 expression was not significantly higher in rosacea tissues than in normal skin tissues. A positive correlation between PAR-2 and cathelicidin within rosacea samples was observed (R=0.330, p=0.037). After treatment of PAR-2 AP, both mRNA and protein levels for PAR-2, cathelicidin, and VEGF significantly increased in cultured keratinocytes, compared with PAR-2 control peptide treatment.ConclusionPAR-2 may participate in the pathogenesis of rosacea through activation of cathelicidin LL-37, a mediator of innate immune responses in the skin.

Comparison of changes in facial skin temperature caused by ethyl chloride spraying, ice block rubbing and cold gel packing in healthy subjects

The aim of this study was to compare the effects of three cryotherapeutic modalities (ethyl chloride spraying, ice block rubbing and cold gel packing) on facial skin temperature. Thirty healthy volunteers (15 men, 15 women; mean age, 29·4±3·2years) participated in this study. Each of the three modalities was randomly applied to the skin over the right masseter muscle. The skin surface temperature was recorded at baseline and every 5min for 60min after the application of one of the three cryotherapeutic modalities. Immediately after application, cold gel packing demonstrated the greatest reduction in surface temperature (10·6°C), followed by ethyl chloride spraying (4·3°C) and ice block rubbing (3·7°C) (P<0·001). During the 60-min post-application period, ethyl chloride spraying and ice block rubbing produced similar skin surface temperature changes. The skin surface remained coldest for the longest period of time after cold gel packing. The median time for recovery of the baseline temperature after application of the cold gel pack was about three to four times longer than that for the other modalities (P<0·001). Ethyl chloride spraying and ice block rubbing resulted in less reduction and faster recovery of skin surface temperature than did cold gel packing. In conclusion, ethyl chloride spraying and ice block rubbing had a limited cooling effect on the facial skin tissue and could not reduce the skin surface temperature enough for local analgesia. Moreover, the cooling effect of cold gel packing was remarkable, but not sufficient for local analgesia.

A new physical model with multilayer architecture for facial expression animation using dynamic adaptive mesh

This paper presents a new physically-based 3D facial model based on anatomical knowledge which provides high fidelity for facial expression animation while optimizing the computation. Our facial model has a multilayer biomechanical structure, incorporating a physically-based approximation to facial skin tissue, a set of anatomically-motivated facial muscle actuators, and underlying skull structure. In contrast to existing mass-spring-damper (MSD) facial models, our dynamic skin model uses the nonlinear springs to directly simulate the nonlinear visco-elastic behavior of soft tissue and a new kind of edge repulsion spring is developed to prevent collapse of the skin model. Different types of muscle models have been developed to simulate distribution of the muscle force applied on the skin due to muscle contraction. The presence of the skull advantageously constrain the skin movements, resulting in more accurate facial deformation and also guides the interactive placement of facial muscles. The governing dynamics are computed using a local semi-implicit ODE solver. In the dynamic simulation, an adaptive refinement automatically adapts the local resolution at which potential inaccuracies are detected depending on local deformation. The method, in effect, ensures the required speedup by concentrating computational time only where needed while ensuring realistic behavior within a predefined error threshold. This mechanism allows more pleasing animation results to be produced at a reduced computational cost.

HFSM: HIERARCHICAL FACIAL SHAPE MODELING ALGORITHM FOR REALISTIC FACIAL EXPRESSION ANIMATION

We propose a hierarchical 3D facial modeling technique for realistic facial expression animation from the anatomical specification. We analyze the real human face to construct the facial model with a hierarchical biomechanical structure, incorporating a physically-based approximation to facial skin tissue, a set of anatomically-motivated facial muscle actuators and underlying skull structure. The deformable skin model has multi-layer structure to approximate different types of soft tissue. It takes into account the nonlinear stress-strain relationship of the skin and the fact that soft tissue is almost incompressible. Different kinds of muscle models have been developed to simulate the distribution of the muscle force exerted to the skin due to muscle contraction. The 3D face model incorporates a skull structure which extends the scope of facial motion and facilitates facial muscle construction. The facial muscle construction is achieved by a muscle mapping approach which efficiently locates facial muscles at the anatomically correct positions between the skin and skull layers. To generate facial expressions, the resulting hierarchical facial model is animated by solving the governing dynamic equation. For computational efficiency, we use a localized, semi-implicit integration method in the numerical simulation. The dynamic facial animation algorithm runs at an interactive rate and synthesizes various realistic facial expressions.

Computerized Morphometric Quantitation of Elastin and Collagen in SMAS and Facial Skin and the Possible Role of Fat Cells in SMAS Viscoelastic Properties

Recently, the superficial musculoaponeurotic system (SMAS) was found to be a composite tissue comprising collagen, elastic fibers, and fat cells in an extracellular viscous matrix. Both SMAS and facial skin tissues exhibit viscoelastic properties, but SMAS tissue has delayed stress relaxation. As a consequence, SMAS is viewed as a firmer elastic foundation for the more viscous facial skin. In some patients, a slackening effect of SMAS tissue takes place over a period ranging from weeks to months after tightening. To determine the relative quantity of viscoelastic components and better understand their biomechanical behavior, a quantitative morphometric study of the elastic and collagen fibers in the SMAS and facial skin was conducted. Thirty-four SMAS preparations were taken from 17 patients during either primary face lift operations (12 women) or reoperative face lift procedures (4 women, 1 man), which were performed 4 to 9 months after the original surgery, to examine the elastin and collagen content. For comparison, preauricular skin was also gathered from these patients. The specimens were stained with Weigert's staining to identify elastin and collagen fibers. Using a computerized morphometric analysis, 100 fields of each SMAS and skin specimen were examined. According to our findings, the average percentage of elastin and collagen fibers in SMAS and facial skin was as follows: (1) the percentage of elastin fibers in the SMAS was 4.71 +/- 1.2 (standard error of mean +/- 0.0291); (2) the percentage of elastin fibers in the skin was 6.1 +/- 1.8 (standard error of mean +/- 0.0436); (3) The percentage of collagen fibers in the SMAS was 38.7 +/- 5.9 (standard error of mean +/- 0.1430); and (4) the percentage of collagen fibers in the skin was 48.47 +/- 6.96 (standard error of mean +/- 0.1688). A statistical significance of p < 0.0001 was demonstrated between the collagen and elastin groups. A different percentage of elastin and collagen fibers was found among the 17 patients and within each of them separately. Neither gender nor age differences were found regarding elastin and collagen fiber content. No statistical differences were demonstrated between specimen sources, i.e., whether the operations were primary or reoperative face lift procedures. Findings from previous studies indicate that the cheek has two viscoelastic layers, the skin and the SMAS. The proportional similarity in average percentages of elastin and collagen in SMAS and facial skin cannot explain the relatively delayed stress relaxation effect of the SMAS. Therefore, the fat cells that are found exclusively in the SMAS probably lend a certain degree of firmness to this layer and play a significant role in the long-term efficacy of SMAS surgery.