Effects of two types of surface treatments on the structural elasticity of human fingernails.

BACKGROUND: The human nail has a three-layered structure. Although it would be useful to quantitatively evaluate the changes in deformability of the nail due to various surface treatments, few studies have been conducted. METHODS: The effects of two types of surface treatment-a chemically acting nail softener and a physically acting nail strengthener-on the deformability of human fingernails were investigated. The Young's modulus of each plate of the nail samples before and after softening treatment was determined by nanoindentation. The Young's modulus of the strengthener was determined by conducting a three-point bending test on a polyethylene sheet coated with the strengthener. RESULTS: Young's modulus decreased in order from the top plate against the softening treatment time, and the structural elasticity for bending deformation (SEB) of the nail sample, which expresses the deformability against bending deformation independent of its external dimensions, decreased to 60% after 6 h of treatment. The Young's modulus of the nail strengthener was 244.5 MPa, which is less than 10% of the SEB of the nail. When the nail strengthener was applied to the nail surface, the SEB decreased to 73%, whereas the flexural rigidity increased to 117%. CONCLUSION: Changes in nail deformability caused by various surface treatments for softening and hardening were quantitatively evaluated successfully.

Nail growth arrest under low body temperature during hibernation.

Growth and differentiation are reduced or stopped during hibernation, an energy conserving strategy in harsh seasons by lowered metabolism and body temperature. However, few studies evaluated this in a same individual using a non-invasive method. In this study, we applied a non-invasive tracking method of the nail growth throughout the hibernation period in the same hibernating animals, the Syrian hamster (Mesocricetus auratus). We found that nail growth was markedly suppressed during the hibernation period but rapidly recovered by the exit from the hibernation period. Our data suggest that nail growth was arrested during deep torpor, a hypometabolic and hypothermic state, but recovered during periodic arousal, a euthermic phase. Consistent with this, nail stem cells located in the nail matrix did not exit the cell cycle in the deep torpor. Thus, hibernation stops nail growth in a body temperature-dependent manner.

Different Numbers of Long-Pulse 1064-nm Nd-YAG Laser Treatments for Onychomycosis: A Pilot Study.

PURPOSE: To examine the benefits of different numbers of 1064-nm Nd-YAG laser treatments in patients with onychomycosis. METHODS: This was a pilot study of patients with onychomycosis who were divided into three groups: four treatment sessions (group A), eight sessions (group B), and 12 sessions (group C). Only infected nails of degrees II-III (Scoring Clinical Index for Onychomycosis) were included. Treatment was given once a week using a long-pulse Nd-YAG 1064-nm laser. Patients were followed at 8, 16, and 24 weeks after the first treatment. Side effects were recorded. RESULTS: Treatments were completed for 442 nails in 102 patients. The efficacy rates at 8, 16, and 24 weeks were 35.5%, 38.7%, and 37.4% for group A; 31.4%, 41.7%, and 44.0% for group B; and 27.7%, 50.0%, and 55.4% for group C, respectively. There was a significant difference in the efficacy rate at 24 weeks (P = 0.016) between groups A and C, but not for groups A vs. B, or for groups B vs. C. No difference in the efficacy rate at 8 or 16 weeks was observed among the three groups. In all three groups, the efficacy was better for degree II nails than for degree III nails (all P = 0.016) between groups A and C, but not for groups A vs. B, or for groups B vs. C. No difference in the efficacy rate at 8 or 16 weeks was observed among the three groups. In all three groups, the efficacy was better for degree II nails than for degree III nails (all. CONCLUSIONS: The 1064-nm Nd-YAG laser had clinical benefits against onychomycosis. Higher numbers of treatments provided better long-term (24-week) benefits, but had no impact on the short-term outcomes. The efficacy of laser treatment on degree II onychomycosis was better than for degree III.

EEMCO Guidance for the in vivo Assessment of Biomechanical Properties of the Human Skin and Its Annexes: Revisiting Instrumentation and Test Modes.

Biomechanics of the skin is an important subject in skin research. It has been studied for many decades involving various technologies and methods to characterize and quantify mechanical properties of the skin under different in vivo conditions. The present EEMCO paper reviews the current rel-evant information, providing practical orientation to researchers dedicated to in vivo assessment of biomechanics of skin and its annexes. We discuss the available non-invasive instruments, including their principles and variables. A correspondence between the descriptors nomenclature proposed by Agache and the designation for the suction-based standard instruments is proposed. The addressed properties include skin softness/stiffness, firmness, elasticity, elastic and viscoelastic properties, extensibility, resilience, anisotropy, acoustical shock wave hardness, friction (in relation to topographic properties), thickness, fiber/stress mechanics (bending, cyclic, tensile, fatigue, or torsion), and hardness. We provide the relation of these properties to biomechanical descriptors and in some cases to SI units. Practical guidance for the proper use of these instruments, limitations, and possible interpretations are provided, while discussing the meaning of descriptive or "phenomenological" variables. For studies intended to quantify the effect of an intervention with regard to mechanical properties, we recommend a minimum of 30-40 participants, based on normal distribution of the data sets. Some important limitations are recognized, including the lack of standardization of procedures and calibration of instruments, which compromises the relevance and real nature of the descriptors/parameters obtained with these devices. The present work highlights an approach to a better practice and a science-supported biomechanical assessment of human skin, hair, and nails.

Repair of thumb defect by using the toenail flap: biomechanical analysis of donor foot-a retrospective cohort study.

BACKGROUND: The thumb accounts for 50% of the total hand function. This study reports the functional outcomes and complications of people with traumatic thumb amputations who underwent toe-to-thumb reconstruction. METHODS: From January 2013 to January 2018, 29 patients with second-degree thumb defect underwent thumb reconstruction with distal phalangeal braided toenail flap. The footscan foot pressure gait analysis system was used to measure the index changes of the same foot before and after 1, 3 and 6 months. The contact area, peak pressure, impulse value, contact time of each gait phase, centre of gravity coordinate and foot balance were analysed statistically. RESULTS: Twenty-nine cases of thumb reconstruction recovered well. After following up for 6-15 months, the appearance of the reconstructed thumb was close to normal, and the sensation was restored to S3+. The two-point discrimination was 6-8 mm, and the function of the thumb was good. The function of the donor foot was well restored, and no skin ulceration, pain and claudication were noted during walking. Compared with that before the operation, the biomechanical indices of the donor foot were basically restored to normal 6 months after the operation. Only the stress and impulse values of the third metatarsal head were significantly increased, forming a stress concentration area centred on the third metatarsal head. CONCLUSIONS: This study confirmed that the toenail flap with distal phalangeal bone restored the second-degree thumb defect without destroying the main functional structure of the sole. The biomechanical indices of the donor foot were basically restored to normal 6 months after the operation. Only the stress concentration area centred on the third metatarsal head, and the pain on the forefoot was induced after the operation. Discomfort, callus formation, metatarsal fasciitis, etc., can lead to fatigue fracture of the third metatarsal bone in severe cases, which requires further follow-up and observation. TRIAL REGISTRATION: Clinicaltrials.gov , NCT03879941; registered on 10 March 2019, retrospectively.

Human nail bed-derived decellularized scaffold regulates mesenchymal stem cells for nail plate regeneration.

Among hand trauma, nail bed is the most involved tissue in hospital emergency departments, resulting in the loss of nail plate, which leads to a disturbance of hand grasp function, long-lasting digit tip pain, hyperpathia, and disesthesia. Treatment of nail bed defects is a significant clinical challenge due to the lack of uniform nail bed thickness and distinct regenerative ability. In this study, it is shown that the extracellular matrix of decellularized nail bed scaffolds can play an important role in inducing bone mesenchymal stem cells to differentiate into nail epithelial cells. Using decellularized nail bed scaffolds combined with bone mesenchymal stem cells, it is revealed that the engineered nail bed can promote nude mouse nail plate regeneration ectopically. The natural extracellular matrix of decellularized nail bed scaffolds can serve as a 3D structural template for bone mesenchymal stem cell differentiation into nail-associated cells, initiating the nail plate regeneration. These results not only provide a proof-of-principle for the generation of transplantable nail grafts based on decellularized nail bed scaffolds derived from clinically wasted amputated fingers but also provide important considerations for clinical treatment for digit tip trauma.

Differences Between Patient-Reported Versus Clinician-Observed Nonulcerative Signs and Symptoms of the Foot in Patients With Diabetes Mellitus.

PURPOSE: The primary aim of this study was to compare patient reported versus clinician-observed nonulcerative foot conditions in patients attending a diabetic foot clinic and deemed at risk for diabetic foot ulcers. DESIGN: Retrospective review of medical records. SUBJECTS AND SETTING: The medical records of 126 patients with diabetes mellitus and deemed at risk for developing diabetic foot ulcers were reviewed. All patients received care from a diabetic foot outpatient clinic in a university-based hospital in Tokyo, Japan, between November 2008 and October 2009. METHODS: We compared patients' self-identified foot complaints with clinically observable conditions affecting the feet of these individuals with diabetes mellitus. Patients' medical records were retrieved, and patient complaints and identified preulcerative signs of the foot were documented. All clinical observations were made by nurse specialists with knowledge of diabetic foot conditions. Nonulcerative diabetic foot conditions we observed included calluses, corns, abnormal nails, fissures, tinea pedis, and tinea unguium. Patient sensitivity to correctly identify these signs was calculated using the following formula: patient-reported foot signs divided by clinically identified preulcerative signs. RESULTS: Patient sensitivity for identifying nonulcerative signs varied based on the foot condition was 51.4% for calluses, 47.8% for pincer nails, 44.4% for corns, 33.3% for fissures, 19.4% for nail abnormalities, 3.9% for scales/maceration between the toes, 2.6% for interdigital tinea pedis, and 18.2% for tinea unguium. CONCLUSION: These findings suggest that persons with diabetes vary in their awareness of conditions affecting their feet and enhancing their risk for the development of diabetic foot ulcers. We recommend additional education on foot-related self-care including how often to observe their feet and how to recognize symptoms that may elevate their risk for diabetic foot ulcers.

Wearable Nail Deformation Sensing for Behavioral and Biomechanical Monitoring and Human-Computer Interaction.

The dynamics of the human fingertip enable haptic sensing and the ability to manipulate objects in the environment. Here we describe a wearable strain sensor, associated electronics, and software to detect and interpret the kinematics of deformation in human fingernails. Differential forces exerted by fingertip pulp, rugged connections to the musculoskeletal system and physical contact with the free edge of the nail plate itself cause fingernail deformation. We quantify nail warpage on the order of microns in the longitudinal and lateral axes with a set of strain gauges attached to the nail. The wearable device transmits raw deformation data to an off-finger device for interpretation. Simple motions, gestures, finger-writing, grip strength, and activation time, as well as more complex idioms consisting of multiple grips, are identified and quantified. We demonstrate the use of this technology as a human-computer interface, clinical feature generator, and means to characterize workplace tasks.

Motor system recruitment during action observation: No correlation between mu-rhythm desynchronization and corticospinal excitability.

Observing others' actions desynchronizes electroencephalographic (EEG) rhythms and modulates corticospinal excitability as assessed by transcranial magnetic stimulation (TMS). However, it remains unclear if these measures reflect similar neurofunctional mechanisms at the individual level. In the present study, a within-subject experiment was designed to assess these two neurophysiological indexes and to quantify their mutual correlation. Participants observed reach-to-grasp actions directed towards a small (precision grip) or a large object (power grip). We focused on two specific time points for both EEG and TMS. The first time point (t1) coincided with the maximum hand aperture, i.e. the moment at which a significant modulation of corticospinal excitability is expected. The second (t2), coincided with the EEG resynchronization occurring at the end of the action, i.e. the moment at which a hypothetic minimum for action observation effect is expected. Results showed a Mu rhythm bilateral desynchronization at t1 with differential resynchronization at t2 in the two hemispheres. Beta rhythm was more desynchronized in the left hemisphere at both time points. These EEG differences, however, were not influenced by grip type. Conversely, motor potentials evoked by TMS in an intrinsic hand muscle revealed an interaction effect of grip and time. No significant correlations between Mu/Beta rhythms and motor evoked potentials were found. These findings are discussed considering the spatial and temporal resolution of the two investigated techniques and argue over two alternative explanations: i. each technique provides different measures of the same process or ii. they describe complementary features of the action observation network in humans.

Wide range of age of onset and low referral rates to psychiatry in a large cohort of acne excoriée at a Swiss tertiary hospital.

INTRODUCTION: Repetitive skin manipulation is the key symptom in skin picking disorder (SPD) or acne excoriée des jeunes filles Brocq. The diagnostic and statistical manual of mental disorders (DSM-5) has recognized SPD as an independent disease, namely an obsessive-compulsive disorder. Thus, psychiatric treatment is indicated. Therefore, in a large cohort of SPD, we asked whether dermatologists' treatment strategy includes routine referrals to psychiatry. In addition, we describe epidemiological data, treatments and follow up. METHODS: We performed a retrospective study, searching in our hospital database between January 1 2011 and December 31 2016. RESULTS: A total of 154 (141 female, 13 male) patients were included in our study. In less than 5% a referral to a psychologist or psychiatrist occurred. More than 90% of all patients received topical and almost 40% systemical anti-acne treatment. The loss of follow-up was very high. DISCUSSION: Our study shows that dermatologists focus on treating acne-like lesions in SPD, but rarely refer to psychiatry. Possible reasons include considerations of patients' reactions who often reject the idea of a psychological origin of the disease. Our results suggest that new treatment strategies should be created to address SPD correctly, i.e. by combined consultations with psychiatrists or specific training of dermatologists in psychiatric therapy and diagnostics.

Nail features in healthy term newborns: a single-centre observational study of 52 cases.

INTRODUCTION: The anatomy and embryology of the nail are well known, and nail abnormalities are a feature of many genodermatoses. However, the physiological aspect is not well described. We aimed to analyse the physiological features of nails in healthy newborns. METHODS: We performed an observational, prospective study at University Hospital Center of Tours between July and October 2015. Newborns were included by a dermatologist assistant during the systematic examination on release of the mother from the hospital. The medical history of the mother and infant were recorded by using a standardized questionnaire. Finger- and toenails were systematically photographed for a second interpretation by a dermatologist with blinding to the first photograph. RESULTS: Fifty-eight patients were eligible, and 52 were included. Half of the newborns were males, and the mean age at inclusion was 3.6 ± 1.2 days. Fingernails had an oval shape (71.1%) or a flat curvature (63.5%), and half had a lunula. Toenails showed an apparent hypertrophy of the proximal nail fold (38.4%) and lateral nail fold (73.1%). The shape of the nails was triangular (50.0%) or round (21.1%). We noted koilonychia in 32.7% of infants and lunula in 7.7%. Distal parts showed onychoschizia (28.8%) and onycholysis (26.9%). CONCLUSION: Koilonychia, onychoschizia of toenails or absence of lunula are physiological features of nails in newborns.

Structural and component mining of nails using bioengineering techniques.

The human nail is one of the challenging membranes for the scientists to target and to improve the clinical efficacy of ungual formulations. The understanding of nail physiology, impact of hydration on its properties and presence of trace elements in nails as biomarkers has been explored by various researchers in clinical studies. Despite the importance of biophysical techniques for the assessment of structure and physiology of nail, minimum literature analyses biophysical, biochemical and bioanalytical approaches. However, nowadays scientists in bioengineering field are keen in developing non-invasive, reliable and reproducible techniques for the assessment of different anatomical and functional parameters of nails for testing of ungual products.

Are fingernails a key to unlocking the puzzle of mammalian limb regeneration?

Some mammalian digit tips, including those of mice and human children, can regenerate following amputation, whereas mammalian limb regeneration does not occur. One major difference between the digit tip and the rest of the limb is the presence of the nail, which is necessary for this type of regeneration. This couples well with the finding that canonical Wnt signalling and Lgr6, an agonist of Wnt signalling that marks nail stem cells, are necessary for digit tip regeneration. This viewpoint essay discusses the role of the nail in digit tip regeneration and explores whether nail stem cells and their presumptive niche can be solely accountable for why regeneration is possible in the digit tip, but not the rest of the limb.

Does Exercise Decrease Pain via Conditioned Pain Modulation in Adolescents?

PURPOSE: Pain relief after exercise, exercise-induced hypoalgesia (EIH), is established across the lifespan. Conditioned pain modulation (CPM: pain inhibits pain) may be a mechanism for EIH. METHODS: In 55 adolescents, pressure pain thresholds were measured before and after exercise (deltoid, quadriceps, and nail bed) and during CPM at the nail bed and deltoid test stimulus sites. The relationship between EIH and CPM was explored. RESULTS: EIH occurred at deltoid and quadriceps; CPM occurred at nail bed and deltoid. CPM and EIH correlated at deltoid; adolescents with greater CPM experienced greater pain relief after exercise. At this site, CPM predicted 5.4% of EIH. Arm lean mass did not add a significant effect. Peak exercise pain did not influence EIH. Adolescents with none, minimal, moderate, or severe peak exercise pain experienced similar EIH. CONCLUSIONS: A potential relationship exists between CPM and EIH in adolescents. Pediatric physical therapists should consider the CPM response when prescribing exercise as a pain management tool.

Automatic data-processing equipment of moon mark of nail for verifying some experiential theory of Traditional Chinese Medicine.

BACKGROUND: Doctors who practice Traditional Chinese Medicine (TCM) diagnose using four methods - inspection, auscultation and olfaction, interrogation, and pulse feeling/palpation. The shape and shape changes of the moon marks on the nails are an important indication when judging the patient's health. There are a series of classical and experimental theories about moon marks in TCM, which does not have support from statistical data. OBJECTIVE: To verify some experiential theories on moon mark in TCM by automatic data-processing equipment. METHODS: This paper proposes the equipment that utilizes image processing technology to collect moon mark data of different target groups conveniently and quickly, building a database that combines this information with that gathered from the health and mental status questionnaire in each test. RESULTS: This equipment has a simple design, a low cost, and an optimized algorithm. The practice has been proven to quickly complete automatic acquisition and preservation of key data about moon marks. CONCLUSION: In the future, some conclusions will likely be obtained from these data; some changes of moon marks related to a special pathological change will be established with statistical methods.

Anatomy of the nail unit and the nail biopsy.

The nail unit is the largest and a rather complex skin appendage. It is located on the dorsal aspect of the tips of fingers and toes and has important protective and sensory functions. Development begins in utero between weeks 7 and 8 and is fully formed at birth. For its correct development, a great number of signals are necessary. Anatomically, it consists of 4 epithelial components: the matrix that forms the nail plate; the nail bed that firmly attaches the plate to the distal phalanx; the hyponychium that forms a natural barrier at the physiological point of separation of the nail from the bed; and the eponychium that represents the undersurface of the proximal nail fold which is responsible for the formation of the cuticle. The connective tissue components of the matrix and nail bed dermis are located between the corresponding epithelia and the bone of the distal phalanx. Characteristics of the connective tissue include: a morphogenetic potency for the regeneration of their epithelia; the lateral and proximal nail folds form a distally open frame for the growing nail; and the tip of the digit has rich sensible and sensory innervation. The blood supply is provided by the paired volar and dorsal digital arteries. Veins and lymphatic vessels are less well defined. The microscopic anatomy varies from nail subregion to subregion. Several different biopsy techniques are available for the histopathological evaluation of nail alterations.

Diagnosis using nail matrix.

Diagnosing nail matrix diseases requires knowledge of the nail matrix function and anatomy. This allows recognition of the clinical manifestations and assessment of potential surgical risk. Nail signs depend on the location within the matrix (proximal or distal) and the intensity, duration, and extent of the insult. Proximal matrix involvement includes nail surface irregularities (longitudinal lines, transverse lines, roughness of the nail surface, pitting, and superficial brittleness), whereas distal matrix insult induces longitudinal or transverse chromonychia. Clinical signs are described and their main causes are listed to enable readers to diagnose matrix disease from the nail's clinical features.

Development of topical therapeutics for management of onychomycosis and other nail disorders: a pharmaceutical perspective.

The human nail plate is a formidable barrier to drug permeation. Development of therapeutics for management of nail diseases thus remains a challenge. This article reviews the current knowledge and recent advances in the field of transungual drug delivery and provides guidance on development of topical/ungual therapeutics for management of nail diseases, with special emphasis on management of onychomycosis, the most common nail disease. Selection of drug candidates, drug delivery approaches, and evaluation of formulations are among the topics discussed. A comprehensive mathematical description for transungual permeation is also introduced.

Morphopathological aspects of healthy nails and nails affected by onychomycosis.

Patients of onychomycosis are common in the dermatology practice. Contemporary morphology creates opportunities to study the functional units of the nail when such infections occur from morphopathological point of view. There were 22 nails biopsies from onychomycosis patients taken for the research of morphopathological changes in the thickened nail plate affected by onychomycosis. Samples of cadaverous' nails were used as a control material. The material was stained with haematoxylin and eosin and immunohistochemical methods. Terminal deoxynucleotidyl transferase dUTP nick end labelling reaction and periodic acid-Schiff reaction were also performed. We found patchy hypertrophy in the granulose layer of the epidermis, with focal acanthosis. In the horn layer, we identified nests of parakeratosis of various sizes, with incorporations of homogenous and eosinophil masses. We found high levels of interleukin 6 and interleukin 10 positive cells in the nail bed and in the bloodstream. Interleukin 1, however, was not a part of any of the functional units of any of the nails. Significant amount of fibres containing human beta defensin-2 were found in the bed and plate of the nail. Therefore one can conclude that as regards the nails affected by onychomycosis, the most effective morphopathogenical processes include cytokine and defensin excretion occurrence in the nail bed.