Skin Surface Replicas Research Articles

Feasibility of skin surface elastography by tracking skin surface topography

Recent advances have led to a multitude of image modalities being used for visualization of tissue stiffness. High-resolution images of tissue stiffness are desirable, as they have the potential to provide useful diagnostic information. A noncontact optical imaging method has the attractions of low cost, simplicity, and utility when skin contact is undesirable. However, previous optical techniques have required the application of paint or ink to the surface of the skin and so have required contact. Therefore, the present study assessed the feasibility of tracking skin surface topography to produce elastograms. The study showed, by analyzing a variety of silicone skin surface replicas from various body sites of subjects of different ages, that skin surface elastography by tracking surface topography would be feasible. The study further showed that the quality of the strain images can be optimized by measuring skin line pattern frequency. Skin samples with high skin line frequency will achieve best spatial resolution, in the order of 1 mm, comparable to contact techniques reported previously. A mechanically inhomogeneous silicone replica was then imaged, illustrating the technique's ability to detect strain contrast. Finally, the feasibility of implementing the technique in vivo was illustrated using a single pigmented skin lesion.

Preliminary performance assessment of computer automated facial approximations using computed tomography scans of living individuals

ReFace (Reality Enhancement Facial Approximation by Computational Estimation) is a computer-automated facial approximation application jointly developed by the Federal Bureau of Investigation and GE Global Research. The application derives a statistically based approximation of a face from a unidentified skull using a dataset of ∼400 human head computer tomography (CT) scans of living adult American individuals from four ancestry groups: African, Asian, European and Hispanic (self-identified). To date only one unpublished subjective recognition study has been conducted using ReFace approximations. It indicated that approximations produced by ReFace were recognized above chance rates (10%). This preliminary study assesses: (i) the recognizability of five ReFace approximations; (ii) the recognizability of CT-derived skin surface replicas of the same individuals whose skulls were used to create the ReFace approximations; and (iii) the relationship between recognition performance and resemblance ratings of target individuals. All five skin surface replicas were recognized at rates statistically significant above chance (22–50%). Four of five ReFace approximations were recognized above chance (5–18%), although with statistical significance only at the higher rate. Such results suggest reconsideration of the usefulness of the type of output format utilized in this study, particularly in regard to facial approximations employed as a means of identifying unknown individuals.

Validation of skin surface microtopography as a measure of skin photoaging in a subtropical population aged 40 and over

Evidence suggests that skin surface microtopography is a valid measure of photoaging among young adults, but whether this applies to older adults is unknown. We investigated the association between degree of photoaging as measured by histological dermal elastosis and skin microtopography grades by decade of age from 40 to 89 years in a community sample in Australia. Skin surface replicas and punch biopsies were taken from 664 participants of the Nambour Skin Cancer Study. The association was assessed using ordinal logistic regression with proportional odds assumption, using histological dermal elastosis grades as outcome. There was significant increase in odds of higher skin surface microtopography grades with higher dermal elastosis grades for age groups below 70 years [40 to 49 years: odds ratio (OR) 2.96, 95% confidence interval (CI) 1.68-5.22; 50 to 59 years: OR 3.78, 95% CI 2.28-6.26; 60 to 69 years: OR 2.47, 95% CI 1.41-4.35). The association was not significant for those 70 years or older. Skin surface microtopography grading system is a valid measure of degree of dermal elastosis for middle-aged and older adults up to 69 years but appears not to be valid for adults 70 years or more living in a high sun exposure setting.

Bioengineering and subjective approaches to the clinical evaluation of dry skin

Dry skin (also known as xerosis) is a cutaneous reaction pattern indicative of abnormal desquamation, which has not only cosmetic considerations, but can also lead to the penetration of irritants and allergens through the stratum corneum (SC). Over the last few decades, our understanding of the structure, composition, formation and function of the SC has advanced tremendously; however, despite these advancements, the occurrence of dry skin remains prevalent in the adult population. The clinical evaluation of dry skin is therefore of significant importance to the cosmetic industry not only for understanding the condition but also for measuring the effects of treatment. Traditionally, dry skin has been evaluated by visual inspection, however, recently a variety of bioengineering techniques have emerged enabling the investigator to objectively assess the extent of xerotic conditions. The most frequently employed methods for the evaluation of dry skin are discussed in this review, including regression testing, squametry, measurement of transepidermal water loss, epidermal hydration, profilometry, confocal Raman spectroscopy, optical coherence tomography, in vivo confocal microscopy and magnetic resonance imaging.

Perioral Wrinkles: Histologic Differences Between Men and Women

Women tend to develop more and deeper wrinkles in the perioral region than men. Although much is known about the complex mechanisms involved in skin aging, previous studies have described histologic differences between men and women with respect to skin aging only incidentally and have not investigated the perioral region. The purpose of this study was to investigate gender-specific differences in the perioral skin. To determine wrinkle severity, skin surface replicas of the upper lip region in 10 male and 10 female fresh cadavers were analyzed by using the dermaTOP blue three-dimensional digitizing system (Breuckmann, Meersburg, Germany). In 30 fresh male and female cadavers, three full-thickness lip resections were investigated in a blinded fashion for specific histologic features. All results were statistically analyzed in a linear regression model with SPSS software (version 15.0; SPSS, Chicago, IL). The female replicas showed more and deeper wrinkles than the male replicas (P < .01). Histologic analysis revealed that the perioral skin of men displayed a significantly higher number of sebaceous glands (P = .000; 95% confidence interval [CI] 23.6-53.2), sweat glands (P = .002; 95% CI 2.1-8.1), and a higher ratio between vessel area and connective tissue area in the dermis (P = .009; 95% CI 0.003-0.021). The amount of hair follicles did not significantly differ between men and women, although the average number of sebaceous glands per hair follicle was greater in men (P = .002; 95% CI 0.33-1.28). Women exhibit more and deeper wrinkles in the perioral region and their skin contains a significantly smaller number of appendages than men, which could be a feasible explanation for why women are more susceptible to development of perioral wrinkles.

Effects of Processed Fabric with Eggshell Membrane on Human Skin Properties

This study aims to clarify the effects of deoxyribonucleic acid (DNA) processed knitted fabric on human skin activity. We used two kinds of DNA, that is, the nucleoprotein extracted from salmon milt and the oligoDNA treated nucleoprotein with enzyme. The oligoDNA contains over 85% DNA. To determine the effects of oligoDNA application, the first experiment was a direct application method that applied an aqueous solution of oligoDNA powder directly to the inside of the upper arm for 14 weeks. The condition of the skin, measured by the water content of the skin, water evaporation from skin, tensile recovery, the microscope images of the replicas of skin surface and subjective feeling showed good results. Therefore, the second experiment applied the oligoDNA by using fabric. Arm bands were made of the knitted fabric processed with the oligoDNA solution and wearing tests were conducted. But this processed fabric was not useful. So, we used the nucleoprotein instead of the oligoDNA and modified the concentration of the solution. The nucleoprotein contains about 40% of DNA and about 60% of protamine. The results showed that the condition of human skin was affected by the modified processed fabric. The effects of the processed fabric on the skin condition were found in the water content of the skin, tensile recovery and the microscope images of the replicas of skin surface after four weeks had passed.

Relationships between changes in mechanical properties of the skin, wrinkling, and destruction of dermal collagen fiber bundles caused by photoaging

Long-term exposure to ultraviolet (UV) radiation induces various cutaneous changes that differ from those because of physiological aging, including structural destruction of dermal collagen fiber bundles (DCFBs), which comprise the major component of the dermis. Wrinkling, a representative change in skin surface associated with photoaging, is often seen at the corners of the eyes and in the space between the eyebrows. These are locations where the skin contracts repeatedly and routinely. Lowered resiliency to skin contraction induced by marked structural changes in DCFBs may represent one cause of photo-induced wrinkles. Using animal models of photoaging, changes in mechanical properties of the skin caused by UV irradiation were measured, and relationships between UV-induced changes were analyzed. Animal models of photoaging were prepared by irradiating hairless mice with UVB light. Dorsal skin surface replicas of animals were taken using silicon rubber, and volume of wrinkles was calculated using an image analyzer. Stress of the skin against horizontal contraction was measured using a new device called the Resiliometer. Three-dimensional organization of dermal collagen structures in skin samples collected from the back of each animal was observed under scanning electron microscopy, and compactness of DCFBs was assessed from electron micrography. With time and therefore increasing UV dose, deep wrinkles formed on the backs of mice. Volume of wrinkles peaked at 8 weeks. All parameters obtained from Resiliometer measurements were increased by irradiation. DCFB structure was degraded in a radiation dose-dependent manner. DCFB grading was significantly correlated with each Resiliometer parameter. Significant correlations were also observed between each Resiliometer parameter and volume of wrinkles. Stress of the skin against horizontal contraction obtained using the Resiliometer changes following UV irradiation, correlating with photo-induced wrinkling and destruction of DCFBs. These results support the hypothesis that changed force of restitution to skin contraction induced by marked structural changes in DCFBs represents one cause of photo-induced wrinkles. The resiliometric parameter may offer a good indicator for monitoring the condition of DCFB structure, as changes in these would induce failure in restitution to skin contraction, leading to wrinkling.

A study of differences in surface roughness between sun-exposed and unexposed skin with age.

To understand and separate the roles of age and solar ultraviolet exposure (sun damage) on the surface roughness of skin. To determine the effects of age and site (sun exposed vs. unexposed) on skin roughness in normal healthy subjects. Using a stylus profilometer and silicone skin surface replicas, we have measured skin surface roughness parameters on habitually exposed (back of hand) and habitually unexposed (upper buttock) skin sites from the same individual in a sample of 73 subjects from the normal population. We compared the two sites in order to determine any differences in roughness caused, we postulate, by the effect of solar ultraviolet exposure on the exposed site. We found that the two sites are indistinguishable in roughness until after 30 years of age. For the over 30 years group, the difference between exposed and unexposed skin roughness correlated strongly with age. For all ages, skin roughness showed a positive correlation with age on the unexposed, but not the exposed, site. On the hand site subjects aged 40 years and older had significantly smoother skin than those aged less than 40 years, as measured by one roughness parameter. On the back, the older group had significantly rougher skin than the younger group measured by two roughness parameters. We propose that on the back of the hands, solar damage reverses or reduces the increase in roughness which would otherwise be caused by intrinsic ageing.

Effect of exposure of human skin to a dry environment.

Changes in the skin conditions after exposure to low humidity have been generally experienced in everyday life, but there have been few reports to approach it-especially in healthy skin. We have examined the effect of low humidity on healthy human skin by using noninvasive measurement devices. Skin conditions on the ventral forearm and the cheek before and after 3 or 6 h exposure to low humidity were evaluated by measuring skin surface conductance, skin surface capacitance and transepidermal water loss. Skin surface replicas were also taken before and after exposure and analysed for roughness parameters--Ra (arithmetic mean roughness value), Rz (10-point height), Sm (mean value of the profile element) and VC1 (anisotropy of skin furrows). There was a significant decrease of water content of stratum corneum at both test sites from the time points 0 h to 3 h and 6 h (P < 0.01) and transepidermal water loss from the time point 0 h to 6 h (P < 0.05). Regarding the roughness parameters, a significant increase of Rz in the directions of 45 degrees/225 degrees and 90 degrees/270 degrees to the body axis and Sm in the directions of 0 degrees/180 degrees (P < 0.05) on the forearm and VC1 (P < 0.05) on the cheek. The parameter Rz also showed a tendency to increase in the directions of 45 degrees/225 degrees (P = 0.06) on the cheek. A specific pattern of the changes to be related to the Langer's lines in the surface morphology was observed. The changes of skin surface pattern in our experiment lead us to consider that exposure to low humidity even in such a short period would be related to inducing aggravation of skin texture and the formation of fine wrinkles. A short exposure of skin to a low-humidity environment induced changes in the moisture contents in the stratum corneum and skin surface pattern, which lead us to assume that a dry environment in our daily life would make fine wrinkles related to lack of water in the stratum corneum.

Automation of a series of cutaneous topography measurements from silicon rubber replicas.

Skin relief is a matter of interest for dermatologists and surgeons. One of the methods available for surface topography measurement is based on 3D profilometry using skin surface replicas. and most studies use statistical results obtained from a large number of skin replica samples. The advent of optical profilometers (without contact) made it possible to remove the solid positive replica and to reduce the duration of the profilometric data acquisition. Nevertheless this saving of time, to be really interesting, needs to automate the data acquisition on a series of negative replicas. By adding a video camera to the optical profilometer and then by processing the resulting images, we have conceived a system able to carry out topographic measurements on a series of replicas loosely organized on a sample holder, without any human intervention. The silicon replicas in use have a very light colour: nearly white, sometimes slightly blue or green. The laser spot of the profilometer is so luminous that its red colour looks white through the camera. When choosing a replica holder with a matt dark colour and marking the left upper corner of the study area on the replica in black ink, the colours to be differentiated on the image are then close to the black one and the white one. We accordingly change the colour camera image into a black and white image (with 256 grey levels) and then carry out thresholdings to separate the different objects or information included in this image. With the use of a perfectly circular replica, of an accurately known size, laid on the sample holder at the center of the area filmed by the camera, we adjust the threshold level, which allows separation of the replica from its holder. We then move this calibrated replica in order to find the relationship between the size in pixels and the real size on the sample holder, in various positions of the video image. The software has four main built-in stages: Moving the sample holder beneath the sensor until a part of a replica is detected in the field of view of the camera; Moving the sample holder until this replica lies just in the middle of the image given by the camera; Recognition of the mark of the upper left corner of the surface area to be measured out inside this replica; and Moving the sample holder until the laser spot of the profilometer coincides with the origin of the surface area to be measured out, then carrying out this measurement. From the upper left corner of the sample holder, a scanning, line-by-line or column-by-column (according to the selected priority direction), is carried out until the successive replicas are found, and is stopped as soon as the number of replicas entered by the operator is reached. The simplicity of the algorithms used makes it possible to distinguish the next measurement area from the preceding one in a few seconds.

3D reconstruction of skin surface from photometric stereo images with specular reflection and interreflection

This paper describes a new method for reconstructing the structure of a skin surface replica from three shading images taken from three different lightings. Since the shading images include specular reflections and interreflection, the conventional photometric stereo method is not suitable for reconstructing its surface structure. In the proposed method, the evaluation function of the surface shape is defined, then the structure is reconstructed by optimizing the evaluation using simulated annealing. The experimental results from both synthetic images and real images demonstrate that the proposed method is more effective for shape reconstruction from shading images which include specular reflection and interreflection. © 1999 Scripta Technica, Electr Eng Jpn, 129(3): 51–58, 1999

Tape stripping of human stratum corneum yields cell layers that originate from various depths because of furrows in the skin.

Tape stripping of human stratum corneum is widely used as a method for studying the kinetics and penetration depth of drugs. Several factors can influence the quantity of stratum corneum that is removed by a piece of tape, such as the manner of tape stripping, the hydration of the skin, cohesion between cells, body site and interindividual differences. However, few data are available about the influence of furrows in the human epidermis on the tape-stripping technique. In this study, we investigated the efficacy of tape stripping in removing complete cell layers from the superficial part of the human stratum corneum. A histological section of skin that was tape-stripped 20 times clearly showed nonstripped skin in the furrows, indicating persistent incomplete tape stripping. Replicas of tape-stripped skin surface demonstrated that even after removing 40 tape strips the furrows were still present. We validated the tape-stripping method further with X-ray microanalysis in the mapping mode by scanning electron microscopy, using a TiO2-containing compound as a marker. TiO2 applied to the skin before the tape-stripping procedures was still present after the tenth tape strip, and was specifically located on the rims of the furrows. We emphasize that results from studies using the tape-stripping method have to be viewed from the perspective that cells on one tape strip of the stratum corneum may be derived from different layers, depending on the position of the tape strip in relation to the slope of the furrow, and such results should be interpreted with considerable caution.

Skin resurfacing with the Ultrapulse carbon dioxide laser. Observations on 100 patients.

The Ultrapulse carbon dioxide (CO2) laser has been shown to be a highly effective treatment for photodamaged skin including improvement of rhytides, precancerous and benign skin lesions, as well as superficial benign pigmented lesions. We describe our experiences using the Ultapulse CO2 laser in treating 100 patients with different severities of photodamaged skin. All patients had moderately or severely photodamaged skin and were selected for treatment with the Ultrapulse CO2 laser to evaluate the efficacy and toxicity of this treatment. The patients were placed on a pretreatment regimen for 2-6 weeks prior to receiving treatment with the Ultrapulse CO2 laser. Patients were evaluated for pre- and posttreatment severity of photodamage. In addition, skin surface replicas were obtained in selected patients and evaluated by computer image analysis technology. At 1 month post-laser treatment, 68 patients received a moderate improvement, five patients achieved a marked improvement, and the remaining 27 patients showed minimal improvement. By 2 months post-laser treatment, 20 of the 27 patients who at 1 month showed only minimal improvement revealed a moderate to marked improvement from baseline. All the patients studied developed a transient erythema that lasted up to 6 weeks, and many of these patients showed a transient hyperpigmentation that persisted for up to 4 months. The Ultrapulse CO2 laser is confirmed as an effective treatment for skin resurfacing of photodamaged skin.

Computer-assisted image analysis of skin surface replicas

Using a rubber-based dental impression material, negative surface impressions were made of demarcated areas of skin and prepared as dry specimens for scanning-electron microscopy. Electron micrographs were taken at low magnification and, using a programmed computer-assisted image analyser, it was possible to represent quantitatively the topography of that particular body site according to the degree of circularity of the various geometric subunits. This technique was most applicable to skin topography with a reliable geometrical pattern of triangles and squares, a feature of hair-bearing surfaces in general and in particular, the antecubital fossa. Using standardized trauma of various types the origin of skin surface markings were found to be located in the dermis. The technique was applied to the healing of experimental trauma produced by tape stripping, the resolution of clinical eczema and a comparison of steroid-treated and untreated tape-stripped skin.

不均一な肌表面への均一なメーク膜の形成

It is a common experience that a makeup which forms a smooth, continuous film when applied on one person may form uneven, unattractive film on another subject. Formulating makeup which can provide perfectly uniform film, regardless the skin condition, remains an unanswered challenge to cosmetic formulators.The purpose of this study was to investigate the reasons for the above difference and to find relationships between the uniformity of the film and the physical properties of the makeup foundation ingredients and the effects of microstructure of the skin surface.Factor analysis of the experimental data indicated that the uniformity of the foundation film had most significant relationship with the evenness of the relief pattern shown by the skin surface replica. Three-dimensional measurements of the replica by a surface roughness meter established that the evenness of the rising portions of the skin surface was the main controlling factor in determining the uniformity of the film.Relationship between the uniformity of the applied film and physical properties of the powder were investigated by determining the uniformity of the powder film applied on the skin or a positive replica. Reduction of the particle size of the powder and prevention of agglomeration were found to promote forming uniform films. A new surface treatment technique by fluoride coating effectively reduced surface activity of the powder, reduced the particle size and eliminated agglomeration. Using this technique and information from this research, we developed a novel makeup which proved to form very uniform film even on uneven skin surface.

Topical tretinoin therapy: Its use in photoaged skin

Tretinoin cream has been used extensively to reverse the changes of photoaging. It is the first topical therapy to undergo controlled clinical testing and proved to be efficacious. These results have been substantiated with photography, histopathologic examination, and skin surface replicas. The mechanism of action of retinoic acid is unknown, but it may bind to a specific receptor that alters the gene expression of the cell. Therapy is most successful when a liberal amount of tretinoin 0.1% cream is applied to the skin daily. Tretinoin cream has an excellent safety record; a local cutaneous hypervitaminosis A reaction is the only common problem.

Quick method of measuring the furrows distribution on skin surface replicas.

A fast method of measuring the distribution of furrows can be obtained via the analysis of TV camera images of skin replicas. These replicas are either negative (or direct) or positive. Reflected or transmitted light is used, depending on the type of replica. Each point of the matrix (256 x 256 pixels) is digitised over 6 bits (64 levels) and treated by a personal computer (IBM AT or PC). With such an image, it is not possible to obtain significant results without eliminating noise and enhancing the furrows. Specific software is written in processor language 8086 to obtain a real time system. The distribution of skin furrows is quantified for several interesting cases such as the ageing of the skin or the effect of stress.

Structural determinants of the response of the skin to chemical irritants.

A study was made of the relationships between structural parameters of the epidermis and stratum corneum and the skin's sensitivities to chemical irritation by dithranol or ammonium hydroxide. Statistically significant positive correlations were found between the minimal blistering time to ammonium hydroxide and the area bounded by the skin surface contour line as determined by a skin surface replica technique. A significant positive correlation was also found between the minimal irritancy dose of dithranol and (a) the mean corneocyte area, and (b) the mean epidermal thickness in cell numbers. Mean corneocyte area was also found to increase with age and to be significantly less in UV-sensitive Types I and II subjects than in the relatively UV-insensitive Types III and IV subjects. These correlations are further evidence that there are inherent structural differences in the skin which influence the way the skin reacts to chemical trauma.

An animal model of solar-aged skin: histological, physical, and visible changes in UV-irradiated hairless mouse skin.

Albino hairless mice (Skh:HR‐l) exposed to sub‐erythemal doses of UVB or UVA radiation display physical, visible, and histological alterations. Skin surface replicas, transepidermal water loss, and skin fold thickness were found to change with irradiation. Visibly, the skin wrinkled with UVB and sagged with UVA exposure. These changes were graded on 3‐point scales. Histological alterations included tissue thickening, loss of elastic fibers, elastosis, loss of collagen, and increases in muco‐substances. The UVB alterations occur to a much lesser extent with an SPF‐15 (7% PABA and 3% oxybenzone) sunscreen product. This sunscreen product had little effect on development of UVA‐induced changes. However, an efficient UVA sunscreen (Parsol 1789) did reduce the UVA‐induced changes. Many of the UVB‐induced alterations regressed after UVB irradiation was stopped. No regression in UVA‐induced alterations was observed when UVA irradiation was stopped. Qualitatively, the effects with UVA irradiation were like those observed in mouse chronological aging. These models and the convenient physical and visible grading methods described can be used to determine the effectiveness of topical treatments, such as sunscreens.

Evaluation of anti‐wrinkle effects on humans

Synopsis Image analysis provides a practical method for studying the cutaneous relief and better understanding of the formation of wrinkles during ageing and their regression induced by an anti-wrinkle product. Quantimet 900 degrees allows a fully automated analysis of 40 replicas of skin surface per cycle of 6 h. The basic principle consists of measuring shadows, generated by incident lighting at the surface of Silflo replicas. Incident light of 38 degrees was selected for analysing crow's feet wrinkles and 26 degrees for the microrelief when crow's feet were absent (slight furrows less than 50 mu-m). The following parameters were recorded: the number of wrinkles, their mean depth, and the coefficient of developed skin surface (CDSS). An O/W emulsion containing 30% biological ingredients was applied daily on the face of 140 female subjects, aged from 20 to 57 years, during 4 weeks. Replicas were made before the first application (t(0)) and 24 h after the last one (t(0)). Data obtained with the image analysis method showed a decrease in number and depth of crow's feet from t(0), to t(4) of 16% and a sharp decrease of the CDSS (30%). No modification of the microrelief was observed. These results were confirmed by measuring forehead casts with the Anaglyphographc(R) apparatus (a profilometric method) on the same subjects: a decrease of 40% in number and 23% in depth were recorded for the forehead wrinkles, with no modification of the microrelief. Both image analysis and profilometry measured the effects provoked by this treatment. The CDSS, which might measure the reservoir of extensibility of the surface of the skin, should be the best parameter to demonstrate the efficiency of anti-wrinkle products.