Volar Forearm Research Articles

Multidimensional outline of experimental techniques for human skin tribology: A scoping review

Human skin tribology involves the study of friction behaviour of skin, with other materials in contact. Numerous studies have been conducted based both on the simulations and experimentations for the tribological investigations. Present study reports key experimental findings post year 2000 in which human skin (in vivo) is taken as test specimen. This review study highlights the latest technologies and trends that is in practice for tribological investigations on the human skin. For the selection of articles, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) technique is adapted. Articles were screened out using various inclusion and exclusion criteria. Classifications were made based on the site of investigations viz. fingertip (22%), finger pad (36%), volar forearm (32%), and other regions (10%) as the anatomical regions. Study concludes that the maximum investigations have been performed on fabric/ textile followed by polymers, metals, plastics, and many others. Shearing has come up as the prominent factor for the erosion of soft surfaces. Study concludes the stick- slip friction to be the foremost contributor to the adhesion friction.

Recovery of microbial DNA by agar-containing solution from extremely low-biomass specimens including skin

Recovering a sufficient amount of microbial DNA from extremely low-biomass specimens, such as human skin, to investigate the community structure of the microbiome remains challenging. We developed a sampling solution containing agar to increase the abundance of recovered microbial DNA. Quantitative PCR targeting the 16S rRNA gene revealed a significant increase in the amount of microbial DNA recovered from the developed sampling solution compared with conventional solutions from extremely low-biomass skin sites such as the volar forearm and antecubital fossa. In addition, we confirmed that the developed sampling solution reduces the contamination rate of probable non-skin microbes compared to the conventional solutions, indicating that the enhanced recovery of microbial DNA was accompanied by a reduced relative abundance of contaminating microbes in the 16S rRNA gene amplicon sequencing data. In addition, agar was added to each step of the DNA extraction process, which improved the DNA extraction efficiency as a co-precipitant. Enzymatic lysis with agar yielded more microbial DNA than conventional kits, indicating that this method is effective for analyzing microbiomes of low-biomass specimens.

The Pressure Is on: Dorsal Versus Volar Univalves for Long-arm Casts.

Fiberglass casts are routinely used to treat fractures of the upper extremity. When posttraumatic edema is anticipated, the cast is often valved to hopefully prevent potential complications, especially compartment syndrome. Due to volar forearm compartments being most involved with upper extremity compartment syndrome, volar skin surface pressures (SSP) are paramount. Despite past literature showing that a univalved cast will retain a 3-point mold better than a bivalved cast, there is a paucity of information analyzing the effects of univalving on the volar SSP. We hypothesized that a volar univalve technique would have a greater decrease in the volar skin surface pressures compared to a dorsal univalve in long-arm casts. A 100-mL saline bag attached to an arterial line pressure transducer was placed between a long-arm cast and the skin along the volar forearm of a single adult volunteer. Fourteen casts were applied by a single certified orthopaedic technologist with 30 years of experience and assigned randomly to receive either a volar or dorsal univalve. We calculated the change in volar forearm SSP on each cast in 4 stages: isolated univalve, with a 3-mm cast spacer, with a 6-mm spacer, and with bivalve. Statistical analysis of the data was performed using a Mann-Whitney U test. When comparing volar versus dorsal univalve, volar SSP significantly dropped by a mean of 32.00 versus 20.43mmHg (P value=0.001) in stage I, 45.14 versus 38.00mmHg in stage II (P value=0.026), and 56.53 versus 49mmHg in stage III (P value=0.001). There was no significant difference between the 2 groups after a bivalve was performed at stage IV (P value=0.318). Our findings support that a volar univalve with a 6-mm spacer will provide the greatest reduction of skin surface pressure while theoretically maintaining the cast's structural integrity and biomechanical properties when compared to a bivalved cast. Level II, prospective comparative study.

Effects of oral morphine on experimentally evoked itch and pain: a randomized, double-blind, placebo-controlled trial.

Pain and itch share similar neuronal networks; hence, it is difficult to explain why opioids can relieve painbut provoke itching. The present human volunteer study aimed to investigate the similarities and differences in responses to experimentally provoked pain and itching to explore the underlying fundamental mechanisms. Twenty-four healthy volunteers were enrolled in this single-center, randomized, double-blind, placebo-controlled, parallel-group trial. Three volar forearms and two mandibular areas were marked, and participants randomly received morphine (20 mg) or identical placebo tablets. Heat, cold, and pressure pain thresholds, and vasomotor responses were assessed at baseline and after oral morphine administration. Itch provocations were induced by intradermal application of 1 % histamine or a topical cowhage (non-histaminergic itch) to a marked area of theskin. The participants were subsequently asked to rate their itching and pain intensities. The assessments were repeated for all marked areas. Morphine caused analgesia, as assessed by the significant modulation of cold and pressure pain thresholds (p<0.05). There were no significant differences in histaminergic or non-histaminergic itch or pain intensity between the morphine and placebo groups. Superficial blood perfusion (vasomotor response) following histamine provocation wassignificantly increased by morphine (p<0.05) in both areas. No correlation was found between the provoked itch intensity and analgesic efficacy in any area or group. Oral administration of morphine caused analgesia without modulating itch intensities but increased neurogenic inflammation in response to histamine, suggesting that different opioid mechanisms in histaminergic and non-histaminergic neurons evoke neurogenic inflammation.

75 Intraoperative Use of Infrared Thermal Imaging Camera – a Clinical Aid for Pedicled Flaps in Hand Reconstruction

Abstract Introduction Venous insufficiency remains one of the commonest causes for flap failure. Forward-looking infrared (FLIR) thermography measures infrared emissions from dissipated heat and converts temperature values into an image. This has various advantages to the current use of indocyanine green (ICG) angiography to assess flap perfusion. Case A man in his mid-30s was involved in a road traffic accident and sustained extensive injuries to his right hand. These included multiple metacarpal fractures, degloving of the proximal aspect of the entire thumb and significant skin loss on the volar distal forearm. After several washouts and tissue debridement, a pedicled chest wall flap was performed. Five weeks later the chest wall flap was divided using an infrared thermal imaging camera (FLIR E5) intraoperatively as a clinical aid to assess perfusion. This detected a small area of venous congestion which was not detectable by clinical assessment. Discussion There are drawbacks to the current intraoperative use of ICG angiography to assess flap perfusion. These include hot flushes and skin rashes, and the technique requires an intraoperative injection, extensive equipment involving a screen and a specialised camera. In comparison FLIR cameras are handheld, easy to use and involves a one-off cost of purchasing the camera that is relatively inexpensive compared to ICG angiography. Conclusions Thermal imaging techniques such as FLIR provides an alternative intraoperative option for patients who are unable to have ICG, for centres that do not have access to ICG and for surgeons looking for more convenient alternatives.

Comparison of brain functional response to mechanical prickling stimuli to the glabrous and hairy skin.

A kind of prickle sensation, which is a composite feeling of pain and itch, can be evoked by mechanical stimulation of fiber ends from fabric surface against to human hairy skin, rather than glabrous skin. Now, a functional magnetic resonance imaging (fMRI) study was conducted to investigate the cognitive differences in the brain for mechanical prickling stimuli to the two types of skin. A nylon filament with the diameter of 205μm and the length of 8mm was used to deliver mechanical prickling stimuli respectively to two skin sites, fingertip (glabrous skin) and volar forearm (hairy skin), of eight healthy male subjects. Simultaneously, the technology of fMRI was adopted to acquire BOLD (Blood Oxygen Level-Dependent) signals of brain functional response of the subjects. Somatosensory areas, emotional areas, and the posterior parietal cortex (especially the precuneus) are important brain regions that distinguish between the two conditions. The representation of mechanical prickling stimulation to glabrous skin in the brain favors much more the tactile information of the stimulation and contains no itch, while the key brain area, precuneus, involved in itch was activated by the same mechanical prickling stimulation to hairy skin, and brain response for the condition of hairy skin contains more emotional information, which plays an important role in pain processing. Therefore, it can be inferred that a kind of stronger prickle sensation, which contains both pain and itch, was evoked by mechanical stimulation to hairy skin than glabrous skin.

Design of a low-frequency ultrasound diagnostic sensor based on skin mechanical impedance

Skin integrity assessment is a very important matter in the nursing care, especially for patients with low mobility. However, the methodology of skin analysis is limited by a lack of reliable yet portable tools. In this paper, a new sensor is proposed for skin mechanical impedance characterisation, aiming to provide an objective assessment of skin health. The device consists in a microcontroller connected to a Langevin transducer. Using the vector control method, the reference vibration of the transducer is assured, and the mechanical impedance is observed. To ensure the repeatability of the measurements, tests in the morning and in the afternoon were taken. To verify if the device can distinguish sites with different mechanical properties on the same body, tests were made on 2 different body sites: the palm of the hand and the volar forearm. Measurements of skin hydration were also taken, to find a potential correlation of these parameters and skin acoustical mechanical impedance. Results have shown that the measurements provided by the device are mostly reliable, and reveal a fair correlation between mechanical impedance and hydration, in the level of stratum corneum, the outermost layer of skin. Also, the device is able to show the difference on the mechanics of the skin in the different body sites tested, independently of the hydration.

The effect of long-term cigarette smoking on selected skin barrier proteins and lipids

The negative impact of cigarette smoking on the skin includes accelerated aging, pigmentation disorders, and impaired wound healing, but its effect on the skin barrier is not completely understood. Here, we studied the changes in selected epidermal proteins and lipids between smokers (45–66 years, smoking > 10 years, > 10 cigarettes per day) and non-smokers. Volar forearm epidermal and stratum corneum samples, obtained by suction blister and tape stripping, respectively, showed increased thickness in smokers. In the epidermis of smokers, we observed a significant upregulation of filaggrin, loricrin, and a trend of increased involucrin but no differences were found in the case of transglutaminase 1 and kallikrein-related peptidase 7, on the gene and protein levels. No significant changes were observed in the major skin barrier lipids, except for increased cholesterol sulfate in smokers. Liquid chromatography coupled with mass spectrometry revealed shorter acyl chains in ceramides, and an increased proportion of sphingosine and 6-hydroxysphingosine ceramides (with C4 trans-double bond) over dihydrosphingosine and phytosphingosine ceramides in smokers, suggesting altered desaturase 1 activity. Smokers had more ordered lipid chains found by infrared spectroscopy. In conclusion, cigarette smoking perturbs the homeostasis of the barrier proteins and lipids even at a site not directly exposed to smoke.

Use of a novel indentometer to evaluate skin stiffness in healthy and diseased human skin.

Mechanical behavior of the skin can be evaluated by different non-invasive methods. In this study, we applied a new measurement device based on indentometry to determine the skin mechanical properties in healthy individuals and in patients with systemic sclerosis (SSc). Three studies were performed. Study 1 included 100 healthy individuals (46 male and 54 female) divided into four age groups with mean ages of 21.5, 28.9, 51.2, and 69.3 years, respectively. Test sites were located on the center of the forehead and the middle of both volar forearms. Study 2 included 16 healthy individuals (two males and 14 females). Test sites were on both volar forearms. Measurements were made before and after the application of Vaseline and emulsion with 12% urea. Study 3 included 20 patients (one male and 19 females) with SSc and 60 age-matched healthy individuals (23 males and 37 females). Test sites were on the center of the forehead and the middle of both volar forearms. Skin stiffness was measured with skin Indentometer IDM 800 (Courage + Khazaka, Cologne, Germany) equipped with two probes with pin diameters of 3 and 5mm, respectively. The stiffer the skin, the less deep the displacement by the indenter. The smaller the diameter, the deeper the pin will go into the skin when using the same force. In addition, the Corneometer CM 820 (Courage + Khazaka) was used to determine epidermal water content in study 2. Indentometric (IDM) values of healthy subjects measured with both probes were lower on the forehead compared to volar forearms. There was no significant difference between both forearms. In all age groups, the IDM values on the male forearms were lower than on the female forearms whereas there was no significant difference on the forehead. In both sex and on all test locations a significant positive correlation between age and IDM values measured with both probes was observed. There was a significant positive correlation between IDM values measured with both probes. The application of moisturizers induced significant changes in epidermal water content whereas the IDM values remained unchanged. At both the forehead and volar forearms, the IDM values in patients with SSc were significantly lower compared to the healthy control skin. The non-invasive indentometric method used can successfully distinguish the changes in normal skin mechanical properties related to age, sex, and anatomical location, as well as in patients with SSc. The method is not appropriate to study the changes related to epidermal hydration.

Decreased role of neuropeptides in the microvascular function in migraine patients with polycystic ovary syndrome

Background and aimsTo understand pathophysiological mechanisms underlying migraine as a cardiovascular risk factor, we studied neuropeptide action and endothelial function as measures of peripheral microvascular function in middle-aged women with or without migraine. MethodsWe included women with the endocrine disorder polycystic ovary syndrome (PCOS), a population with supposed elevated cardiovascular risk, with and without comorbid migraine. In 26 women without and 23 women with migraine in the interictal phase (mean age 50.8 ± 2.9 years) local thermal hyperemia (LTH) of the skin of the volar forearm was measured cross-sectionally under control conditions, after inhibition of neuropeptide release by 5% lidocaine/prilocaine (EMLA) cream application, and after inhibition of nitric oxide formation by iontophoresis of NG-monomethyl-l-arginine (L-NMMA). Hereafter, changes in the natural logarithm of the reactive hyperemia index (lnRHI) and augmentation index (AI) during reperfusion after occlusion-derived ischemia were measured. ResultsWhile mean values under control conditions and L-NMMA conditions were similar, migraine patients had a significantly higher mean area of the curve (AUC) of the total LTH response after EMLA application than those without (86.7 ± 26.5% versus 67.9 ± 24.2%; p = 0.014). This was also reflected by a higher median AUC of the plateau phase under similar conditions in women with migraine compared to those without (83.2% (IQR[73.2–109.5]) versus 73.2% (IQR[54.3–92.0]); p = 0.039). Mean changes in lnRHI and AI scores were similar in both groups. ConclusionsIn PCOS patients with migraine, neuropeptide action was lower compared with those without migraine. While larger studies are warranted, these findings provide a potential mechanism supporting previous findings that migraine may be independent from traditional risk factors, including atherosclerosis.

Interrater reproducibility of the Myoton and durometer devices to quantify sclerotic chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD) is a severe complication in long-term survivors of allogeneic hematopoietic stem cell transplantation. This disease is challenging to manage clinically due to a lack of validated tools to quantitatively measure skin sclerosis. The current gold standard for measuring skin sclerosis is the NIH Skin Score which has only moderate agreement among clinicians and experts. To more accurately assess skin sclerosis in cGVHD, the Myoton and durometer devices can be used to directly measure biomechanical parameters of the skin. However, the reproducibility of these devices is not known in patients with cGVHD. To determine this reproducibility, three observers independently measured 10 anatomic sites in each of seven patients with sclerotic cGVHD using the Myoton and durometer. Clinical reproducibility was measured by mean pairwise differences (U-statistic) and intraclass correlation coefficients (ICCs) with 95% confidence intervals (CIs). Mean pairwise differences, expressed in true physical units, were used to report typical errors for each anatomic site and device. Mean pairwise differences were less than 11% of the average overall values for all five Myoton parameters and durometer hardness. These were lower for Myoton creep (4.1%), relaxation time (4.7%), and frequency (5.1%) than decrement (9.0%), stiffness (10.4%), and durometer hardness (9.0%). Myoton parameters creep, relaxation time, and frequency showed promise for capturing skin biomechanics more accurately than Myoton stiffness, decrement, or durometer hardness. Mean pairwise differences trended highest in the shin and volar forearm and lowest in the dorsal forearm. The interobserver ICC for overall (averaged across all measured body sites of a patient) creep (0.94; 95% CI 0.87-1.00), relaxation time (0.96; 95% CI 0.90-1.00), and frequency (0.95; 95% CI 0.88-1.00), trended higher than that for decrement (0.43; 95% CI 0.00-0.88), stiffness (0.92; 95% CI 0.81-1.00), and durometer hardness (0.82; 95% CI 0.61-1.00). Similar trends were observed in healthy participants. These findings can help clinicians design better studies to assess therapeutic response to new cGVHD treatments and support the interpretation of future measurements.

In vivo detection of healthy skin: Comparison of multiphoton microscopy and reflectance confocal microscopy.

Noninvasive skin examination evolved rapidly in recent years, with multiphoton microscopy (MPM) and reflectance confocal microscopy (RCM) being used to image in-vivo skin at high resolution. The aim of this study is to compare the imaging clarity between the two techniques and measure the thickness of the epidermis in different body sites. We also measured the degree of skin aging with noninvasive tools. Fifty-six volunteers were evaluated and measured at three different body sites, including the cheek, volar forearm, and back. We used RCM and MPM to evaluate the clarity of each skin layer, including stratum corneum, stratum granulosum, stratum spinosum, dermo-epidermal junction, and dermis. We measured epidermal thickness (ET) at the three body sites in individuals of different ages and genders. We assessed skin aging by the second harmonic to autofluorescence aging index of dermis (SAAID), and multiple linear regression was used to analyze the factors affecting SAAID. MPM had advantages in observation of stratum granulosum, collagen fiber, and elastic fiber (p<0.001), but RCM provided better observation in dermo-epidermal junction layer (p<0.001). The epidermis was thicker in the cheek area than the volar forearm and back in both RCM and MPM detection, and the average ET measured by MPM was lower than RCM. ET varied among the three body sites with significant differences (p<0.05). ET was significantly lower at almost all sites in individuals above 40y (p<0.05). SAAID decreased with age, and more rapidly in women. Cheeks have lower SAAID scores than other body sites. MPM and RCM provide noninvasive methods for imaging skin and each method has its own advantages. Epidermal thickness and SAAID correlated with age, gender, and different body sites. MPM could also assess the degree of skin aging, which could guide the clinical treatment of patients with diffferent ages and genders in the above body sites.

Age-dependent changes in epidermal architecture explored using an automated image analysis algorithm on in vivo reflectance confocal microscopy images.

Reflectance confocal microscopy (RCM) allows for real-time in vivo visualization of the epidermis at the cellular level noninvasively. Parameters relating to tissue architecture can be extracted from RCM images, however, analysis of such images requires manual identification of cells to derive these parameters, which can be time-consuming and subject to human error, highlighting the need for an automated cell identification method. First, the region-of-interest (ROI) containing cells needs to be identified, followed by the identification of individual cells within the ROI. To perform this task, we use successive applications of Sato and Gabor filters. The final step is post-processing improvement of cell detection and removal of size outliers. The proposed algorithm is evaluated on manually annotated real data. It is then applied to 5345 images to study the evolution of epidermal architecture in children and adults. The images were acquired on the volar forearm of healthy children (3 months to 10 years) and women (25-80 years), and on the volar forearm and cheek of women (40-80 years). Following the identification of cell locations, parameters such as cell area, cell perimeter, and cell density are calculated, as well as the probability distribution of the number of nearest neighbors per cell. The thicknesses of the Stratum Corneum and supra-papillary epidermis are also calculated using a hybrid deep-learning method. Epidermal keratinocytes are significantly larger (area and perimeter) in the granular layer than in the spinous layer and they get progressively larger with a child's age. Skin continues to mature dynamically during adulthood, as keratinocyte size continues to increase with age on both the cheeks and volar forearm, but the topology and cell aspect ratio remain unchanged across different epidermal layers, body sites, and age. Stratum Corneum and supra-papillary epidermis thicknesses increase with age, at a faster rate in children than in adults. The proposed methodology can be applied to large datasets to automate image analysis and the calculation of parameters relevant to skin physiology. These data validate the dynamic nature of skin maturation during childhood and skin aging in adulthood.

Permanent fillers—What is their role

AbstractBackgroundWith the growing cosmetic industry, there have been numerous advancements in nonsurgical interventions including the use of permanent dermal filler injections. Permanent fillers are relatively novel in clinical use when compared to temporary and semi‐permanent fillers. The only FDA‐approved, non‐biodegradable permanent filler uses polymethylmethacrylate (PMMA) microspheres. PMMA is suspended in bovine collagen and lidocaine solution for injection, absorbed by the body, and replaced overtime by collagen. ArteFill® was the first FDA approved permanent filler in 2005 for correction of nasolabial folds, with studies demonstrating rejuvenation for up to five years, trumping its predecessors in longevity. A decade later with rebranding, Bellafill® was indicated for correction of nasolabial fold and atrophic acne scars.AimsTo review the development of permanent fillers, mechanism, and safety.Materials &amp; MethodsA qualitative systematic review was conducted on PMMA microspheres indications, contraindications, and off‐label use on benefits, risks, and adverse events.ResultsThe durability of permanent fillers has a strong appeal for both patients and practitioners, however, usage for certain patient populations demonstrates increased risk for both early and late complications compared to temporary and semi‐permanent fillers. A skin test composed of purified 3.5% bovine collagen gel administered in the volar forearm is recommended one month prior to injection, to identify any patients who may have a positive response. Bovine collagen demonstrates low immunogenicity with the incidence of preexisting hypersensitivity reported to be between 2‐4%. Bovine collagen in dermatologic formulations use pepsin‐solubilized formulations in which telopeptides are cleaved to further help reduce aberrant immunogenic responses.DiscussionEarly and late complications may outweigh the benefits in use of permanent fillers, however these complications are patient dependent.ConclusionPermanent fillers may be useful in volume replacement for nasolabial folds and atrophic acne scars, however a provider must use good clinical judgement in deciding which patients are ideal candidates.

The impact of dupilumab on skin barrier function: A systematic review.

Skin barrier dysfunction plays an important role in atopic dermatitis (AD) aetiopathogenesis. Dupilumab, a drug that inhibits IL-4 and IL-13, is an effective treatment for AD but there is scarce evidence about its impact on epidermal barrier. The objective of this systematic review is to evaluate the influence of dupilumab on skin barrier in patients with AD using non-invasive tools. A systematic review was designed following PRISMA guidelines. The literature search identified 73 references and, finally, only 6 were selected, including a total of 233 participants. All the studies were prospective observational studies. Dupilumab improved clinical scores in all the research. Skin barrier function parameters were mainly measured on the volar forearm. Transepidermal water loss (TEWL) was the parameter most frequently measured, evaluated in all the studies. Dupilumab decreased TEWL on eczematous lesions and non-involved skin. About 33.6% (2/6) studies reported that dupilumab also increased stratum corneum hydration (SCH) on eczematous lesions while one study did not report any changes in this parameter. This drug also decreased temperature and improved ceramide composition. In conclusion, dupilumab improved skin barrier function in AD patients, mainly reflected in a decreased in TEWL values.

Effects of impermeable and semipermeable glove materials on resolution of inflammation and epidermal barrier impairment after experimental skin irritation.

Semipermeable membranes might be suitable for glove liners or comfort gloves in individuals with irritant contact dermatitis (ICD). To evaluate the effects of different glove materials on inflammation and epidermal barrier impairment after experimental skin irritation. Nine test areas on the volar forearms of 24 healthy volunteers were irritated with sodium lauryl sulfate (1%) and afterward covered for 6 days (6 or 8 h/day) with semipermeable Sympatex (SYM), vinyl (OCC), combinations of vinyl with Sympatex (SYM/OCC) or cotton (COT/OCC), or left uncovered (CON). Up to day 10, measurements of transepidermal water loss (TEWL), erythema (a*), skin humidity (SH) and visual scoring (VS) were applied. No significant differences in skin parameters were found between COT/OCC and SYM/OCC as well as between each of the combinations and CON. SYM, COT/OCC and SYM/OCC led to better results for most skin parameters than OCC alone. Occlusive material has a negative impact on skin barrier recovery and inflammation after skin irritation whereas SYM is not inferior to uncovered areas indicating good tolerability. Altogether, the data suggest that SYM is a useful alternative to COT as material for glove liners and comfort gloves in ICD patients.

α-ionone promotes keratinocyte functions and accelerates epidermal barrier recovery.

As a common fragrance ingredient, α-ionone is widely used in cosmetics, perfume, and hygiene products. Nevertheless, little information is available for its biological activities on the skin. In this study, we investigated the effect of α-ionone on keratinocyte functions associated with skin barrier repair and further evaluated its skin barrier recovery capacity to explore its therapeutic potential for the treatment of skin barrier disruption. The effect of α-ionone on the keratinocyte functions including cell proliferation, migration, and production of hyaluronic acid (HA) and human β-defensin-2 (HBD-2) were examined in vitro using human immortalized keratinocytes (HaCaT cells) as experimental model. The barrier recovery effects of topical hydrogels containing 0.1% or 1% α-ionone were tested on the volar forearm of 31 healthy volunteers by measuring transepidermal water loss (TEWL) and stratum corneum (SC) hydration following barrier disruption induced by repeated tape-stripping. The statistical significance was evaluated by one-way analysis of variance (ANOVA) followed by a Dunnett's post-hoc test. α-ionone promoted HaCaT cell proliferation (P<0.01) dose-dependently in the 10 to 50 µM range. Meanwhile, it also increased the intracellular cyclic adenosine monophosphate (cAMP) levels (P<0.05). Furthermore, HaCaT cells treated with α-ionone (10, 25, 50 µM) showed enhanced cell migration (P<0.05), up-regulated gene expression of hyaluronic acid synthases 2 (HAS2) (P<0.05), HAS3 (P<0.01), and HBD-2 (P<0.05), and enhanced production of HA (P<0.01) and HBD-2 (P<0.05) in the culture supernatant. These beneficial actions of α-ionone were abrogated by cAMP inhibitor, suggesting that its effects are cAMP-mediated in HaCaT cells. In vivo study showed that topical application of α-ionone-containing hydrogels accelerated the epidermal barrier recovery of human skin after barrier disruption by tape stripping. Treatment with hydrogel containing 1% α-ionone resulted in a significant increase of above 15% in the barrier recovery rate at day 7 post-treatment when compared to the vehicle control (P<0.01). These results demonstrated the role of α-ionone in the improvement of keratinocyte functions and the epidermal barrier recovery. These findings suggest possible therapeutic application of α-ionone in the treatment of skin barrier disruption.

In vivo transepidermal water loss: Validation of a new multi-sensor open chamber water evaporation system Tewameter TM Hex.

Instrumentation technology for transepidermal water loss measurements has not been substantially modified since its introduction by Nilsson in 1977. Recent progress in sensor development allowed a new sensor arrangement using a matrix of 30 sensors. Raw measurement values are processed with spatial statistical analysis. We aimed to compare the new, multi-sensor probe (Tewameter TMHex) with the established Tewameter TM300 probe and to gain reference data for the new parameters of transepidermal energy loss and water vapor concentration on skin. Baseline measurements and repeated measurements on the volar forearm and assessment on eight different anatomical locations were performed on 24 healthy volunteers (both gender) with the TMHex and the TM300. A significant correlation (p<0.001; R-coefficient=0.9) between TMHex and the TM300 with a low coefficient of variance (CV) 11% for TMHex and 19% for TM300, could be assessed. The CV ranged between 7% (right inner upper arm) and 14% (palms). Average transepidermal heat loss ranged from 12W/m2 on the lower leg to 38.8W/m2 on the palm. The correlation between TMHex and TM300 along with the robustness of the measurements with the TMHex shows that the new probe for assessment of epidermal barrier function is comparable to the TM300. In most conditions, TMHex provides more accurate measurements than TM 300. New parameters open the field to studying skin's water and energy balance.

Effect of an Emollient Emulsion Containing 15.0% of Caprylic/Capric Triglyceride on the Urocanic Acid of the Stratum Corneum.

Natural moisturizing factor (NMF) includes several compounds in the stratum corneum (SC), among them, urocanic acid (UCA). Ultraviolet (UV) exposure turns the trans-UCA of the SC into its cis isomer. We investigated the impact of a topical emollient emulsion treatment on the UCA isomers of the SC exposed to artificial UV stress. Aliquots of emollient emulsion were applied in healthy subjects for 2 h on delimited areas of the volar forearm, then, the SC was removed by tape stripping. Tapes were irradiated in a solar simulator chamber and a high performance liquid chromatograph was used to quantify UCA isomers from stripped SC extract. The amount of both UCA isomers were almost twice higher in the SC treated with the emollient emulsion. We also observed that the UV irradiation elevated the amount of the cis/trans UCA ratio on the SC (non-treated and treated), suggesting that the emollient sample was not able to avoid the UCA isomerization. The in vivo tests corroborated with the UCA data obtained ex vivo, since we found an increase in the superficial skin hydration with respective reduction of the TEWL, probably occurring by the occlusion performed by the emollient emulsion containing 15.0% w/w of caprylic/capric triglyceride.

Moisturizing at a molecular level - The basis of Corneocare.

This review covers the last 20 years of research we and our collaborators have conducted on ethnic differences in facial skin moisturization placed in historical context with previous research. We have focussed particularly on the biochemical and cellular gradients of the stratum corneum (SC) with the aim of discovering new skin moisturization and SC maturation mechanisms, identifying new technologies and/or providing conceptual innovations for ingredients that will improve our understanding and treatment of dry skin. Specifically, we discuss gradients for corneodesmosomes and proteases, corneocyte phenotype-inducing enzymes, filaggrin and natural moisturizing factor (NMF), and barrier lipids. These gradients are interdependent and influence greatly corneocyte maturation. The interrelationship between corneodesmolysis and the covalent attachment of ω-hydroxy ceramides and ω-hydroxy fatty acids to the corneocyte protein envelope forming the corneocyte lipid envelope is especially relevant in our new understanding of mechanisms leading to dry skin. This process is initiated by a linoleoyl-ω-acyl ceramide transforming enzyme cascade including 12R lipoxygenase (12R-LOX), epidermal lipoxygenase-3 (eLOX3), epoxide hydrolase 3 (EPHX3), short-chain dehydrogenase/reductase family 9C member 7 (SDR9C7), ceramidase and transglutaminase 1. Our research has opened the opportunity of using novel treatment systems for dry skin based on lipids, humectants, niacinamide and inhibitors of the plasminogen system. It is clear that skin moisturization is a more complex mechanism than simple skin hydration.