Human Skin Surface Research Articles

Age-dependent variation in cytokines, chemokines, and biologic analytes rinsed from the surface of healthy human skin.

In the skin, aging is associated with overall epidermal thinning, decreased barrier function, and gradual deterioration of the epidermal immune response. However, the presence and role of cytokines, chemokines, and biologic analytes (CCBAs) in immunosenescence are not known. Here we identified age-related changes in skin properties and CCBAs from stratum corneum of healthy human subjects, providing a means to utilize CCBAs as benchmarks for aging skin health. Transepidermal water loss and a(*) (skin redness) decreased in an age-dependent manner, and were significantly lower (p < 0.05) in Groups 2 (56.6 ± 4.6 years) and 3 (72.9 ± 3.0 years) vs. Group 1 (24.3 ± 2.8 years). In skin wash fluid, 48 CCBAs were detected; seven were significantly lower (p < 0.05) in Groups 2 and 3: EGF, FGF-2, IFNα2, IL-1RA, HSA, keratin-6, and involucrin; cortisol was significantly higher (p < 0.05) in Groups 2 and 3. Our results correspond with the pro-inflammatory shift that occurs with immunosenescence and also provides basis for understanding the inflammatory changes in normal aging skin.

Mapping The Human Skin Surface

The skin’s surface has long been terra incognita. Although scientists have charted some of its molecular makeup, they haven’t had a detailed map. But now, researchers have reported a three-dimensional plot of the microbes and molecules found on the surface of human skin (Proc. Natl. Acad. Sci. USA 2015, DOI: 10.1073/pnas.1424409112). The map blazes a trail for understanding the interplay among health, hygiene, and the human microbiome. This project “gives a much more detailed view of how microbes and metabolites change over the surface of the body than our previous work in this area,” says Rob Knight, a professor of biomedical sciences at the University of California, San Diego, who has been involved in previous microbiome projects and was responsible for the microbial sequencing performed in the new study. To map the composition of the skin, the researchers swabbed 400 1-inch-square spots on each of two volunteers, a man and ...

Molecular cartography of the human skin surface in 3D

The human skin is an organ with a surface area of 1.5-2 m(2) that provides our interface with the environment. The molecular composition of this organ is derived from host cells, microbiota, and external molecules. The chemical makeup of the skin surface is largely undefined. Here we advance the technologies needed to explore the topographical distribution of skin molecules, using 3D mapping of mass spectrometry data and microbial 16S rRNA amplicon sequences. Our 3D maps reveal that the molecular composition of skin has diverse distributions and that the composition is defined not only by skin cells and microbes but also by our daily routines, including the application of hygiene products. The technological development of these maps lays a foundation for studying the spatial relationships of human skin with hygiene, the microbiota, and environment, with potential for developing predictive models of skin phenotypes tailored to individual health.

Skin Impedance Measurements by Means of Novel Gold Sensors Fabricated by Direct Writing

In this paper impedance sensors designed for measurement of skin impedance are described. The design of our sensors is simple and efficient. Thanks to their geometry accurate results average impedance measurements over the skin surface was obtained. Measurements were performed in KCl water solution and at the surface of human skin. RC equivalent circuit model was developed and fitted to measurements data. Different types of sensors (6 types) make possible to tune measurement set-up for specific properties of the skin (e.g. low or high skin impedance which differs among persons). Based on the proposed RC equivalent circuits including Warburg impedance element, the most universal skin model was elaborated.

A Portable Human Skin Tester Based on Resistance and Capacitance Measurement

A portable tester for accessing the electrical properties of human skin surface is reported. A pair of interdigital electrodes (IDE) that contact directly with the human skin, is used as the sensing element. The impedance of the sensing system is modeled as a resistance and a capacitance in series. A square wave signal is applied so that impedance of the IDE is measured in a charging/discharging way. The response voltages of the IDE at two excitation frequencies, 10 kHz and 600 Hz, are measured successively during one measurement cycle. Since the equivalent capacitance of skin performs different frequency-dependent property other than the resistance, their values can be resolved from the measured response voltages. A microprocessor-based system is implemented as a prototype battery-powered portable unit for household measurements. Good repeatability and satisfied accuracy have been obtained by experimental results.

The response of human thermal sensation and its prediction to temperature step-change (cool-neutral-cool).

This paper reports on studies of the effect of temperature step-change (between a cool and a neutral environment) on human thermal sensation and skin temperature. Experiments with three temperature conditions were carried out in a climate chamber during the period in winter. Twelve subjects participated in the experiments simulating moving inside and outside of rooms or cabins with air conditioning. Skin temperatures and thermal sensation were recorded. Results showed overshoot and asymmetry of TSV due to the step-change. Skin temperature changed immediately when subjects entered a new environment. When moving into a neutral environment from cool, dynamic thermal sensation was in the thermal comfort zone and overshoot was not obvious. Air-conditioning in a transitional area should be considered to limit temperature difference to not more than 5°C to decrease the unacceptability of temperature step-change. The linear relationship between thermal sensation and skin temperature or gradient of skin temperature does not apply in a step-change environment. There is a significant linear correlation between TSV and Qloss in the transient environment. Heat loss from the human skin surface can be used to predict dynamic thermal sensation instead of the heat transfer of the whole human body.

The long-term use of soap does not affect the pH-maintenance mechanism of human skin.

The pH at the surface of healthy human skin is around 5. Cleansing the skin with soap increases the pH of the skin, which then returns to a more acidic pH within a few hours. However, the effects of skin cleansing with soap over a long time on the pH regulatory system is still unclear. We compared the pH of the skin between users of a soap-based cleanser and of a mild-acidic cleanser prior to and following the cleansing. This study had two groups of subjects, one group who had used a soap-based cleanser for more than 5 years and the other group who had used a mild-acidic cleanser for more than 5 years. The pH on the inner forearm of each subject was measured prior to and for 6 h after cleansing with a soap bar. There were no differences between the pH of the skin these two groups prior to cleansing, immediately after cleansing or in the pH recovery rate for 6 h. These results suggest that long-term continuous use of a soap-based cleanser does not affect the pH-maintaining mechanism of human skin.

Detecting cannabis use on the human skin surface via an electronic nose system.

The most commonly used drug testing methods are based on the analysis of hair and urine using gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry or immunoassay screening. These methods are time-consuming and partly expensive. One alternative method could be the application of an “electronic nose” (eNose). We have developed an eNose to detect directly on the human skin surface metabolic changes in the human body odor caused by cannabis consumption. Twenty cannabis-smoking and 20 tobacco-smoking volunteers were enrolled in this study. For the sensor signal data processing, two different methods were applied: Principle component analysis (PCA) with discriminant analysis, and the method of pattern recognition with subsequent support vector machines (SVM) processing. The PCA analysis achieved a correct classification of 70%, whereas the SVM obtained an accuracy of 92.5% (sensitivity 95%, specificity 90%) between cannabis-consuming volunteers and tobacco-smoking subjects. This study shows evidence that a low-cost, portable and fast-working eNose system could be useful for health protection, security agencies and for forensic investigations. The ability to analyze human body odor with an eNose opens up a wide field for diagnosing other drugs and also various diseases.

Fingerprint Recovery from Human Skin by Finger Powder

An examination experiment has been carried out to investigate whether fingerprint powder and lifting technique can recover and transfer latent fingerprints from human skin surfaces of dead bodies. For recovery Swedish Black powder and for transfer White Fingerprint Gelatine were used. Crime scene investigation is a process that aims at recording the scene as it is first encountered, and recognizing and collecting all physical evidence potentially relevant to the solution of the case. Crime scene investigators who have received comprehensive forensic training usually quickly take over the work at the scene and implement ideas from research institutes in practice. The personnel processing crime scenes should be aware of equipment necessary to process a crime scene and a mechanism to secure and transport the evidence to the laboratory. Physical evidence has the potential to play a critical role in the overall investigation and resolution of a suspected criminal act. We can therefore say that in investigating crimes, we are using traditional investigative approaches with modern methods and state of the art tools.

In vitro skin penetration of acetyl hexapeptide-8 from a cosmetic formulation

There is a concern that peptides in cosmetic creams marketed as anti-aging/anti-wrinkle may penetrate into the deep layers of the skin and potentially stimulate biological activity. Claims for one cosmetic peptide, acetyl hexapeptide-8 (Ac-EEMQRR-amide), suggest interference with neuromuscular signaling as its anti-wrinkle mechanism of action. Therefore, the skin penetration of commercially available Ac-EEMQRR-amide from a cosmetic formulation (oil-in-water (O/W) emulsion) was determined in hairless guinea pig (HGP) and human cadaver skin assembled into in vitro diffusion cells. An O/W emulsion containing 10% Ac-EEMQRR-amide was applied to skin at a dose of 2 mg/cm2. After a 24-h exposure, the skin surface was washed to remove unabsorbed peptide. Skin disks were tape stripped to determine the amount of peptide in the stratum corneum. Removal of the stratum corneum layers was verified by confocal microscopy. The epidermis was heat separated from the dermis and each skin fraction was homogenized. Skin penetration of Ac-EEMQRR-amide was measured in skin layers by hydrophilic interaction liquid chromatography with tandem mass spectrometry using electrospray ionization (ESI) in the positive mode. Stable isotopically labeled hexapeptides were used as internal standards for the quantitation of native hexapeptides to correct for matrix effects associated with ESI. The results (percent of applied dose) showed that the majority of the Ac-EEMQRR-amide was washed from the surface of both HGP and human skin. Ac-EEMQRR-amide that penetrated skin remained mostly in the stratum corneum of HGP (0.54%) and human (0.22%) with the peptide levels decreasing as each layer was removed by tape stripping. Total Ac-EEMQRR-amide found in the epidermis of HGP and human skin was similar at 0.01%. No peptide was detected in the dermis or buffer collected underneath the skin for both human and HGP. There was no hexapeptide metabolite (H2N-EEMQRR-amide) detected in any layers of HGP skin, human skin or buffer collected underneath the skin. This skin penetration data will be useful for evaluating the safety of cosmetic products containing small peptide cosmetic ingredients.

Staphylococcal Bicomponent Pore-Forming Toxins: Targets for Prophylaxis and Immunotherapy

Staphylococccus aureus represents one of the most challenging human pathogens as well as a common colonizer of human skin and mucosal surfaces. S. aureus causes a wide range of diseases from skin and soft tissue infection (SSTI) to debilitating and life-threatening conditions such as osteomyelitis, endocarditis, and necrotizing pneumonia. The range of diseases reflects the remarkable diversity of the virulence factors produced by this pathogen, including surface antigens involved in the establishment of infection and a large number of toxins that mediate a vast array of cellular responses. The staphylococcal toxins are generally believed to have evolved to disarm the innate immune system, the first line of defense against this pathogen. This review focuses on recent advances on elucidating the biological functions of S. aureus bicomponent pore-forming toxins (BCPFTs) and their utility as targets for preventive and therapeutic intervention. These toxins are cytolytic to a variety of immune cells, primarily neutrophils, as well as cells with a critical barrier function. The lytic activity of BCPFTs towards immune cells implies a critical role in immune evasion, and a number of epidemiological studies and animal experiments relate these toxins to clinical disease, particularly SSTI and necrotizing pneumonia. Antibody-mediated neutralization of this lytic activity may provide a strategy for development of toxoid-based vaccines or immunotherapeutics for prevention or mitigation of clinical diseases. However, certain BCPFTs have been proposed to act as danger signals that may alert the immune system through an inflammatory response. The utility of a neutralizing vaccination strategy must be weighed against such immune-activating potential.

Smart Thermometer Technology for Detection and Monitoring of More than 100 Diseases at Home

Smart Thermometer Technology is intended for early detection and objective monitoring of more than 100 diseases (inflammatory, vascular and tumor) by measuring the temperature of the area of interest on human skin surface. The technology includes fast-operating infrared sensors that can be connected by wireless communication to mobile devices, available to a user (smart phones, tabs, etc.) with built-in specialized thermography software. It measures the temperature of any areas of human skin surface via infrared sensor point by point, generates thermogram and automatically gives comprehensive to an average person report about the state of the examined area and dynamics of the pathological process after each monitoring session. Self-examination of one anatomical area takes no more than 1 minute. Smart Thermometer Technology allows us to increase the accuracy of monitoring of a disease, and in most cases without participation of a doctor, simplify and cheapen obtaining of information on the course of a pathologic process and obtaining of the conclusion on the effectiveness of treatment.

Hardware Infection with Corynebacterium spp.: a Case Report and Review of the Literature

There are over 120 species in the genus Corynebacterium, many of which are generally non-pathogenic. Isolates are frequently recovered from human clinical specimens, but because Corynebacterium spp. are known to be colonizers of human skin and mucosal surfaces, they are often not identified to the species level due to limitations in identification methods and lack of consensus concerning their clinical relevance. In this article, we present a case report demonstrating the difficulty and importance of distinguishing different strains of Corynebacterium isolated from a patient with a post-operative spine infection and review the current literature. This case illustrates not only the role of molecular diagnostics in determining the etiology of infection, but also the diagnostic subtleties that remain for the clinical microbiologist and infectious disease practitioner regarding the genus Corynebacterium.

Genome Sequence of Staphylococcus massiliensis Strain S46, Isolated from the Surface of Healthy Human Skin

Staphylococcus massiliensis strain S46 was isolated from the surface of healthy human skin. Here, we report the draft genome sequence of S. massiliensis S46 (2,447,110 bp, with a G+C content of 36.3%).

A study of human skin and surface temperatures in stable and unstable thermal environments

Skin temperature is a common physiological parameter that reflects human thermal responses. The purpose of this research was to investigate the effects of radiant temperature on human skin temperature and surface temperature in stable and unstable thermal environments. For a clothed human body, the skin temperature is the surface temperature of the skin, while the surface temperature is the outer surface temperature of the clothes. For this aim, the radiant temperature from 26 to 38°C and then from 38 to 26°C was controlled in three different ways; in stable condition keeping stable above 40min, in unstable condition at a rate of 2°C/5min, and in another unstable condition at a rate of 2°C/10min. Experimental data showed that at the same radiant temperature, the local skin/surface temperatures during the radiant temperature decrease were higher compared to those during the radiant temperature increase. During the radiant temperature increase/decrease, the increments/decrements of the mean skin temperature and the mean surface temperature decreased gradually from the stable condition, 2°C/10min to 2°C/5min. Compared to surface temperature, the faster the radiant temperature changed, the more obviously the change in skin temperature was delayed. These data demonstrated that the human body has physiological adaptability to unstable thermal environments.

A Graphical Approach for Human Skin Moisture Evaluation by Electrical Impedance Spectroscopy

A pair of concentrically placed gold electrodes is utilized in contact with human skin surface for moisture evaluation. The electrical impedance spectroscopy is measured within a frequency range of 100Hz to 5MHz. It is showed that, in case of relatively dried stratum corneum, reproducibility of measured impedances will decrease significantly in lower frequency range. The integrality of impedance frequency locus is correspondingly dependent on skin moist state. On the other hand, in case of relatively wetted stratum corneum, an integral locus can be obtained and Cole-Cole arc model can be applied for quantitative calculation. The integrality of the locus is introduced as a supplemental parameter. Experimental results with moistened filter paper as well as human skin indicate that, the skin moisture can be better represented both graphically and quantitatively.

Thermal phase transition behavior of lipid layers on a single human corneocyte cell

We have improved the selected area electron diffraction method to analyze the dynamic structural change in a single corneocyte cell non-invasively stripped off from human skin surface. The improved method made it possible to obtain reliable diffraction images to trace the structural change in the intercellular lipid layers on a single corneocyte cell during heating from 24°C to 100°C. Comparison of the results with those of synchrotron X-ray diffraction experiments on human stratum corneum sheets revealed that the intercellular lipid layers on a corneocyte cell exhibit essentially the same thermal phase transitions as those in a stratum corneum sheet. These results suggest that the structural features of the lipid layers are well preserved after the mechanical stripping of the corneocyte cell. Moreover, electron diffraction analyses of the thermal phase transition behaviors of the corneocyte cells that had the lipid layers with different distributions of orthorhombic and hexagonal domains at 24°C suggested that small orthorhombic domains interconnected with surrounding hexagonal domains transforms in a continuous manner into new hexagonal domains.

Bacterial lysates in food allergy prevention

In the concept of food allergy prevention, no successful strategy could be identified until now. Although interventional trials using probiotics, prebiotics, hydrolyzed formula and bacterial lysates early in infancy were found to reduce the incidence of atopic dermatitis, no effect on food sensitization and allergy could be shown. Studies in a farming environment showed that early contact to livestock, bacteria and moulds may upregulate the immune responses regulated via Toll-like receptors and thus prevent allergy. There is increasing evidence that the unbalanced composition of the human microbiome on human skin and mucosal surfaces may be a key player in the development of inflammatory diseases like allergy and asthma. However, during the last 5 years, this concept could not yet be verified in the interventional trials. There are few studies using bacterial lysates, for example, Escherichia coli plus Enterococcus faecalis in ProSymbioflor and heat-killed Bifidobacterium breve and Streptococcus thermophilus; however, food allergy prevalence could not be reduced by these interventions. During the last 5 years, new interventional trials addressed the use of bacterial lysates. There was only an effect on eczema in the ProSymbioflor trial, whereas the trial using B. breve and S. thermophilus in a cow's milk formula showed a slight reduction of food sensitization at the age of 12 months. However, these strategies need further investigation and success seems to be restricted to certain subpopulations.

Monte Carlo simulation of light reflection from cosmetic powder particles near the human skin surface

The reflection and scattering properties of light incident on human skin covered with powder particles have been investigated. A three-layer skin structure with a pigmented area is modeled, and the propagation of light in the skin's layers and in a layer of particles near the skin's surface is simulated using the Monte Carlo method. Assuming that only single scattering of light occurs in the powder layer, the simulation results show that the reflection spectra of light from the skin change with the size of powder particles. The color difference between normal and discolored skin is found to decrease considerably when powder particles with a diameter of approximately 0.25 μm are present near the skin's surface. The effects of the medium surrounding the particles, and the influence of the distribution of particle size (polydispersity), are also examined. It is shown that a surrounding medium with a refractive index close to that of the skin substantially suppresses the extreme spectral changes caused by the powder particles covering the skin surface.

Molecular Probes in Tandem Electrospray Ionization Mass Spectrometry: Application to Tracing Chemical Changes of Specific Phospholipid Molecular Species

New ionization and detection techniques in mass spectrometry have been successfully applied for efficient analyses of complex biological systems. It is, however, still difficult to trace structural changes of a specific molecular species in such systems. In the present study, a molecular probe strategy in combination with tandem electrospray ionization mass spectrometry has been examined using synthetic deuterium-labeled phosphatidylcholine hydroperoxide (PC-OOH/D3) and ethyl-labeled phosphatidylcholine having docosahexaenoic acid side chain (DHA-PC/Et). Administration of a mixture of PC-OOH/D3 and DHA-PC/Et to human blood and human skin surface, followed by extraction and analysis with collision-induced tandem electrospray ionization mass spectrometry demonstrated that metabolites of both molecular probes can be detected simultaneously with strict selectivity. The present method is also found to be useful in tracing chemical changes of the unstable docosahexaenoyl group on the surface of processed fish. The activity of phospholipase A2 can also be assessed using a phospholipid molecular probe with a linoleoyl and a deuteriomethyl group via selective detection of the lyso-phospholipid product by mass spectrometry. The advantage of the present method is that no chromatographic separation is required and analysis can be performed under strictly the same condition for different molecular probes, affording multiple data by one experiment. The present strategy may be useful for tracing time-dependent phenomena in dynamic phospholipid biochemistry, and can be widely used for any biological and food systems.