Cell differentiation in the embryonic periderm and in scaffolding epithelia of skin appendages.

Terminal differentiation of epithelial cells is critical for the barrier function of the skin, the growth of skin appendages, such as hair and nails, and the development of the skin of amniotes. Here, we present the hypothesis that the differentiation of cells in the embryonic periderm shares characteristic features with the differentiation of epithelial cells that support the morphogenesis of cornified skin appendages during postnatal life. The periderm prevents aberrant fusion of adjacent epithelial sites during early skin development. It is shed off when keratinocytes of the epidermis form the cornified layer, the stratum corneum. A similar role is played by epithelia that ensheath cornifying skin appendages until they disintegrate to allow the separation of the mature part of the skin appendage from the adjacent tissue. These epithelia, exemplified by the inner root sheath of hair follicles and the epithelia close to the free edge of nails or claws, are referred to as scaffolding epithelia. The periderm and scaffolding epithelia are similar with regard to their transient functions in separating tissues and the conserved expression of trichohyalin and trichohyalin-like genes in mammals and birds. Thus, we propose that parts of the peridermal differentiation program were coopted to a new postnatal function during the evolution of cornified skin appendages in amniotes.

The limb dorsoventral axis: Lmx1b's role in development, pathology, evolution, and regeneration.

The limb anatomy displays well-defined dorsal and ventral compartments, housing extensor, and flexor muscles, which play a crucial role in facilitating limb locomotion and manipulation. Despite its importance, the study of limb dorsoventral patterning has been relatively neglected compared to the other two axes leaving many crucial questions about the genes and developmental processes implicated unanswered. This review offers a thorough overview of the current understanding of limb dorsoventral patterning, synthesizing classical literature with recent research. It covers the specification of dorsal fate in the limb mesoderm and its subsequent translation into dorsal morphologies-a process directed by the transcription factor Lmx1b. We also discuss the potential role of dorsoventral patterning in the evolution of paired appendages and delve into the involvement of LMX1B in Nail-Patella syndrome, discussing the molecular and genetic aspects underlying this condition. Finally, the potential role of dorsoventral polarity in digit tip regeneration, a prominent instance of multi-tissue regeneration in mammals is also considered. We anticipate that this review will renew interest in a process that is critical to limb function and evolutionary adaptations but has nonetheless been overlooked.

Detection of 2-ethyl-1-hexanol and its modulating effect in biofilm of Fusarium oxysporum.

In immunocompetent individuals, Fusarium spp. stands out as the causative agent of onychomycosis, among the non-dermatophyte molds. Despite evidence indicating that Fusarium oxysporum organizes itself in the form of a biofilm causing onychomycosis, there is little literature on the etiopathogenesis of the biofilm on the nail, specifically the signaling molecules present, known as quorum sensing (QS). Thus, this study detected the presence of a molecule related to QS from the ex vivo biofilm of F. oxysporum on human nail and investigated its effect on preformed biofilm in vitro. The detection and physicochemical characterization of a QS molecule, from the extracellular matrix (ECM), was carried out by Fourier transform infrared (FTIR) spectroscopy with an attenuated total reflectance (ATR) accessory and by headspace gas chromatography coupled to mass spectrometry (GC-MS) analyses. Determination of viable cells, cell activity, total biomass, ECM components and scanning electron microscopy (SEM) were performed to evaluate the influence of the QS molecule on the in vitro biofilm of F. oxysporum. The beginning, in the ex vivo biofilm of F. oxysporum on human nails, the volatile organic compound 2-ethyl-1-hexanol (2EH) was detected as a component of QS. Thereafter in vitro analyses, synthetic 2EH was able to modulate the biofilm by stimulating its filament, increasing total biomass and ECM production in terms of total carbohydrates, but with a reduction in total proteins and nucleic acids. We thus evidence, for the first time, the presence of 2EH in the biofilm of F. oxysporum, developed on the human nail, and the in vitro action of this compound as a QS molecule.

Association of the clinical components in the distal interphalangeal joint synovio-entheseal complex and subsequent response to ixekizumab or adalimumab in psoriatic arthritis.

OBJECTIVES: To assess the frequency of simultaneous distal interphalangeal (DIP) joint disease and adjacent nail psoriasis (finger unit) among patients with psoriatic arthritis (PsA) and compare the efficacy of the interleukin (IL)-17A antagonist ixekizumab (IXE) and the tumour necrosis factor (TNF)-α inhibitor adalimumab (ADA). METHODS: This post hoc analysis evaluated the simultaneous occurrence of DIP joint involvement (tenderness and/or swelling) and adjacent nail psoriasis among patients with PsA from the SPIRIT-H2H (NCT03151551) trial comparing IXE to ADA. Among patients with simultaneous DIP joint involvement and adjacent nail psoriasis in ≥ 1 digit at baseline, treatment effects were assessed through week 52 for each affected finger unit; 'finger unit' defines the connected DIP joint and adjacent nail of an individual digit. RESULTS: A total of 354 patients had simultaneous DIP joint involvement and adjacent nail psoriasis in ≥ 1 finger unit at baseline. Among them, 1309 (IXE = 639, ADA = 670) finger units had baseline DIP joint tenderness and/or swelling and adjacent nail psoriasis. Proportions of affected finger units achieving complete resolution were significantly higher with IXE vs ADA as early as week 12 (38.8% vs 28.4%, p< 0.0001) and at all post-baseline assessments through week 52 (64.9% vs 57.5%, p= 0.0055). CONCLUSIONS: In this study cohort, patients with DIP joint involvement almost always had adjacent nail psoriasis. Greater resolution of DIP joint tenderness, swelling, and adjacent nail psoriasis was achieved at all timepoints over 52 weeks through targeting IL-17A with IXE than TNF-α with ADA, which is noteworthy given prior comparable musculoskeletal outcomes for both drug classes.

De novo enhancer deletion of LMX1B produces a mild nail-patella clinical phenotype.

Critical genes involved in embryonic development are often transcription factors, regulating many downstream genes. LMX1B is a homeobox gene that is involved in formation of the limbs, eyes and kidneys, heterozygous loss-of-function sequence variants and deletions cause Nail-Patella syndrome. Most of the reported variants are localised within the gene's coding sequence, however, approximately 5%-10% of affected individuals do not have a pathogenic variant identified within this region. In this study, we present a family with four affected individuals across two generations with a deletion spanning a conserved upstream LMX1B-binding sequence. This deletion is de novo in the mother of three affected children. Furthermore, in this family, the manifestations appear limited to the nails and limbs, and therefore may reflect an attenuated phenotype of the classic Nail-Patella phenotype that includes ophthalmological and renal manifestations.

Nail fold capillaroscopy in leprosy: Unveiling the microvascular changes.

BACKGROUND: Leprosy, a chronic infectious disease, is associated with various nail changes. Its etiopathogenesis is multifaceted, with microvascular damage being crucial. Nail fold capillaroscopy (NFC) emerges as a novel tool for detecting early vascular deficits in leprosy. The study aimed to assess and provide a complete clinical characterization of NFC changes in leprosy patients. METHODS: It is an observational cross-sectional study, done over a period of 1.5 year (January 2021 to august 2022) in a tertiary care hospital, encompassing 60 patients diagnosed with leprosy (18-60 years). After obtaining informed consent; detailed history, complete cutaneous and neurological examinations were conducted. All fingernails and toenails were examined for clinical changes. Subsequently, onychoscopy was performed using USB type of video-dermatoscope (Model AM7115MZT Dino-lite), a non-invasive tool. This was followed by NFC which was done for all fingernails and images were recorded by single operator, which were then assessed for quantitative and qualitive changes and statistical analysis was conducted using SPSS v20, with mean capillary density compared using Student's t-test, morphological change frequencies assessed by proportions, and group comparisons made using Chi-square or Fischer exact tests, with a significance threshold of p < 0.05. RESULTS: Among the 60 patients, 39 were in the lepromatous group, which included both borderline lepromatous (BL) and lepromatous leprosy (LL) patients, and 17 were in the tuberculoid group, which included borderline tuberculoid (BT) leprosy patients; 23.3 % had Type 1 reactions, and 18.3 % had Type 2 reactions. Nail fold capillaroscopy (NFC) showed microvasculature changes in 93.3 % of patients. The average capillary density was 6.8 ± 1.5 capillaries per mm, with the lepromatous group having a lower density (6.5 ± 1.09) compared to the tuberculoid group (7.0 ± 0.86). The most common NFC changes in the tuberculoid group were tortuous capillaries (70 %), capillary dropouts, and dilated capillaries (both 64.7 %). In the lepromatous group, capillary dropouts (82 %) were most frequent, followed by tortuous (69 %), receding (69 %), and dilated capillaries (66 %). A dilated and prominent subpapillary plexus was more common in the lepromatous group (35 %, p = 0.04). Patients with trophic changes in the lepromatous group had more capillary dropouts and bizarre capillaries. Capillary dropouts, dilated capillaries, and visible subpapillary venous plexus were more prevalent in patients with Type 2 reactions. CONCLUSION: NFC changes are prevalent in both tuberculoid and lepromatous leprosy, which may be an indicator of peripheral vascular compromise and trophic changes, especially in lepromatous leprosy. NFC can be an auxiliary tool for detecting microvascular abnormalities in leprosy patients.

Multiple nail gun injuries: suicide or homicide?

Nail gun injuries are a forensic problem; it can be difficult to distinguish self-inflicted injuries from accident and homicide instances. This kind of injuries shares some characteristics with both gunshot and puncture wounds. We describe a peculiar case of a man who committed suicide driving nails into his skull using a pneumatic nail gun. Entrance wounds were found on both temporal regions of the head. Reviewing scientific literature, this is the first case in Italy reporting the macroscopic data of bilateral head and brain nail gun injuries during an autopsy. Circumstantial elements were not sufficient to clarify if these lesions were self-inflicted, inflicted by accident, or else. Radiological examination can be helpful to show the exact location of the nails, but it has also its own limitations. We firmly believe that autopsy, especially the head section, is crucial to identify the nature and the extension of these lesions, thus giving us much more information about the mechanism of death and the circumstances in which it occurred.

Dermoscopic features of nails in Leprosy patients in a tertiary referral hospital in West Java, Indonesia.

INTRODUCTION: Leprosy is a chronic granulomatous infectious disease, mainly affecting the skin and peripheral nerves, caused by the obligate intracellular bacteria Mycobacterium leprae. The disease has been discussed in several review articles in recent research, but as far as we know, only a few have addressed the effects of leprosy on nails, especially those who examine the dermoscopic features of nails in leprosy patients. PURPOSES: We aimed to document nail changes in leprosy patients and identify any particular findings through dermoscopic examination. METHOD: This was an observational study conducted in the Dermatology and Venereology Clinic of Hasan Sadikin Hospital, West Java, Indonesia, from March 2023 through May 2023. All patients have established cases of leprosy, and the diagnosis is based on clinical and bacteriological examinations. Recruitment was done through total sampling. Dermoscopic examination of all fingernails and toenails was performed at 10x magnification using a handheld dermatoscope (Heine DELTA 20 T Dermatoscope) in polarized mode without the linkage fluid to document the dermoscopic features. RESULT: Of a total of 19 patients, 15 had nail changes due to leprosy. Out of 15 patients, 13 patients were male. Patients below 25 years old had more nail changes. Most of the patients had a duration of disease greater than two years. Both fingers and toes were involved in nine patients. In this study, the most common dermoscopic feature found was the longitudinal ridge. Other dermoscopic features found in this study were transverse lines, onycholysis, longitudinal melanonychia, leukonychia, subungual hemorrhage, subungual hyperkeratosis, anonychia, and onychorrexis. CONCLUSION: Nail changes are found in leprosy patients and have a wide variety of clinical appearances. A dermoscopy should be performed to assess nail changes in leprosy.

Assessment of Human Exposure to Traditional and Novel Organophosphate Esters via Multiple Personal Matrices.

Herein, 16 traditional and 13 novel organophosphate esters (OPEs) in skin wipes, personal PM2.5, sputum, and nails (fingernails and toenails) and 7 OPE metabolites in urine synchronously obtained from 64 college students were analyzed. Similar compositional profiles of the OPEs were found in skin wipes and nails and in personal PM2.5 and induced sputum. Significant correlations were observed between the concentrations of high-lipophilicity low-volatility OPEs in skin wipes and nails and between the concentrations of high-volatility low-lipophilicity OPEs in personal PM2.5 and sputum. These results imply that OPEs in fingernails and toenails may mainly come from external sources rather than internal exposure, and human nails and sputum can be used as indicators of human exposure to OPEs. A comparison between the daily exposure doses of the OPEs in personal PM2.5 and sputum shows that more volatile compounds may have higher inhalation bioavailability, which should be considered to improve the accuracy of inhalation exposure assessments. According to comprehensive external and internal exposure assessment, dermal absorption may be a more dominant pathway than inhalation, and skin wipes may be the best representative environmental matrix of human exposure to OPEs.

Nail psoriasis and nail lichen planus: Updates on diagnosis and management.

BACKGROUND: Inflammatory diseases of the nail, including nail psoriasis and nail lichen planus, are associated with significant disease burden and have a negative impact on quality of life. Diagnosis is often delayed, especially when patients present without cutaneous findings. Therefore, recognizing clinical signs and symptoms of inflammatory nail diseases, and initiating timely and appropriate treatment, is of utmost importance. OBJECTIVE: We review recent studies on diagnostic techniques, discuss severity grading and scoring systems, and describe consensus treatment recommendations for nail psoriasis and nail lichen planus. METHODS: An updated literature review was performed using the PubMed database on studies assessing diagnostic techniques or treatment modalities for nail psoriasis and nail lichen planus. RESULTS: Recent studies on diagnostic techniques for inflammatory nail disease have focused on use of dermoscopy, capillaroscopy, and ultrasound modalities. Treatment of these conditions is dichotomized into involvement of few (≤3) or many (>3) nails. Recent psoriatic therapeutics studied for nail outcomes include brodalumab, tildrakizumab, risankizumab, deucravacitinib, and bimekizumab, while emerging treatments for nail lichen planus include JAK inhibitors and intralesional platelet rich plasma injections. CONCLUSIONS: We emphasize the need for increased awareness and expanded management strategies for inflammatory nail diseases to improve patient outcomes.

Clinical, onychoscopic, nail clipping, and histopathological findings of malignant onychopapilloma.

This report describes the clinical, onychoscopic, nail clipping, and histopathologic features of a malignant onychopapilloma. A 71-year-old male presented to our outpatient clinic for a stable, asymptomatic lesion on his left middle finger that had been present for 2 years. Prior nail clipping histopathology showed nail plate thinning with subungual abnormal onychocytes. Clinical examination revealed a 2-mm-wide streak of longitudinal xanthonychia extending to the proximal nail fold, with distal hyperkeratosis and onycholysis. Onychoscopy showed irregular longitudinal nail plate ridging with scattered punctate hemorrhagic foci. An excisional nail unit biopsy demonstrated cellular atypia of the nail bed epithelium, matrix metaplasia, longitudinal abnormal onychocytes, increased Ki-67 staining, and negative HPV immunoperoxidase staining, confirming the diagnosis of malignant onychopapilloma.

A case of superficial acral fibromyxoma masquerading as squamous cell carcinoma of the thumb: A case report.

A wide spectrum of tumors may affect the periungual spaces of the digits. Superficial acral fibromyxoma (SAF) is a rare, benign soft tissue tumor with diverse clinical presentations. We present a case of a 55-year-old woman with a 2-year history of a solitary periungual tumor on the left thumb, subjected to multiple episodes of trauma. Initially suspected to be a periungual squamous cell carcinoma (SCC) based on clinical and dermoscopic features, the tumor was confirmed to be a CD34- SAF through histopathology and immunohistochemistry. Although CD34 immunoreactivity is common in SAF, one-third of these tumors, including this case, do not stain for this marker. Periungual SCC considered a "great mimicker of nail tumors," may resemble other benign nail tumors such as SAF. The patient underwent complete surgical excision with primary closure, resulting in no recurrence after 1 year. This case highlights SAF as an underrecognized benign entity that may manifest with features suspicious of malignancy, potentially leading to unnecessarily aggressive interventions. Recognizing SAF through accurate biopsy techniques and thorough histopathologic evaluation, even in the absence of CD34 reactivity, is crucial for appropriate treatment and preservation of hand function and appearance.

Nail-patella syndrome with nephropathy in a de novo LMX1B mutation: triangular lunula of the thumb and lack of finger creases as clues.

Nail-patella syndrome (NPS) is an autosomal dominant disease caused mostly by mutations in the LMX1B gene and is characterized by hypoplastic nails, hypoplastic patella, elbow deformities, glaucoma, and nephropathy, sometimes leading to kidney failure. The combination and the severity of symptoms vary greatly from patient to patient. Because a kidney biopsy may show nonspecific findings, patients with nephropathy alone may not be diagnosed without undergoing genetic testing. We examined the case of a 6-year-old girl with persistent high proteinuria who was not diagnosed by kidney biopsy but had a diagnosis of a de novo mutation in the LMX1B gene following genetic testing. Retrospectively, only the thumbs showed triangular lunulae, while the third and fourth fingers lacked skin creases over the distal interphalangeal joints, which is subtle but characteristic of NPS. Notifying pediatric nephrologists of these findings can help avoid unnecessary kidney biopsies and lead to early detection of the disease.

The Typical Nail Lichen Planus Severity Index: An Outcome Instrument for Typical Nail Lichen Planus.

INTRODUCTION: Despite numerous treatment options for nail lichen planus (NLP), a validated method for measuring the severity of NLP and therapeutic response in clinical trials is absent. The aim of the study was to develop and validate a measurement instrument, Typical Nail Lichen Planus Severity Index (tNLPSI), for typical NLP that could be used in clinical trials. METHODS: A total of 48 patients pathologically confirmed with typical NLP were enrolled in this study. Five dermatologists were trained to use the tNLPSI activity scale and the Physician's Global Assessment (PGA) scale to score samples independently to estimate inter-rater and intra-rater reliability across two sessions. In addition, tNLPSI activity scores were compared with PGA scores to assess the construct validity. RESULTS: The tNLPSI activity scale had excellent internal consistency and inter-rater reliability (Cronbach's alpha 0.990; ICC = 0.954; 95% CI = 0.930-0.971), and the correlations between the different graders' scores indicate good consistency (rp = 0.934-0.968). In addition, the tNLPSI activity scale demonstrated high intra-rater reliability (ICC = 0.996; 95% CI = 0.993-0.998), showing good reproducibility. And tNLPSI activity scores and PGA scores showed good construct validity (Spearman's rho = 0.941 and Spearman's rho = 0.903-0.935, respectively; p < 0.01). CONCLUSION: The tNLPSI activity scale was demonstrated to be consistent, reliable, reproducible, and feasible, making it a potential valuable tool for evaluating the treatment response in typical NLP clinical trials.

Yellow Nail Syndrome: Analysis of 23 Consecutive Patients and Effect of Combined Fluconazole-Vitamin-E Treatment.

INTRODUCTION: Yellow nail syndrome (YNS), a very rare disorder of unknown etiology, is characterized by a triad associating yellow nails, respiratory manifestations, and lymphedema. YNS treatment remains non-codified. METHOD: This retrospective study was conducted from January 2008 to December 2022 in a single tertiary department exclusively dedicated to lymphatic diseases. All consecutive patients with YNS were included. RESULTS: Thirteen men and 10 women were included. Three patients had yellow nails at birth or during childhood. For the other 20 patients, median (Q1-Q3) age at first sign was 50.8 (43-61) years, with first-YNS-sign-to-diagnosis interval of 17 (10-56) months. For 4 patients, YNS was associated with primary intestinal lymphangiectasia. The first YNS sign was chronic cough (45.5%), followed by yellow nails (27.3%), chronic sinusitis (18.2%), and lymphedema (9.1%). At first consultation for all patients, 69.6% had the complete triad, all had yellow nails and cough, 82.6% had chronic sinusitis, and 69.6% had lymphedema. Twelve patients' lymphedema involved only the lower limb(s), 2 the lower and upper limbs, and 2 the lower and upper limbs and face. Nineteen (82.6%) patients were prescribed fluconazole (100 mg/day [n = 8] or 300 mg/week [n = 11]) combined with vitamin E (1,000 mg/day) for a median of 13 months. Responses were complete for 4 (21.1%) patients, partial for 8 (42.1%), and therapeutic failures for 7 (36.8%). CONCLUSIONS: YNS is a rare disease that almost always starts with a chronic cough. Despite inconstant efficacy, fluconazole-vitamin E in combination can be prescribed to treat yellow nails.

Numerical evaluation of internal femur osteosynthesis based on a biomechanical model of the loading in the proximal equine hindlimb.

Femoral fractures are often considered lethal for adult horses because femur osteosynthesis is still a surgical challenge. For equine femur osteosynthesis, primary stability is essential, but the detailed physiological forces occurring in the hindlimb are largely unknown. The objective of this study was to create a numerical testing environment to evaluate equine femur osteosynthesis based on physiological conditions. The study was designed as a finite element analysis (FEA) of the femur using a musculoskeletal model of the loading situation in stance. Relevant forces were determined in the musculoskeletal model via optimization. The treatment of four different fracture types with an intramedullary nail was investigated in FEA with loading conditions derived from the model. The analyzed diaphyseal fracture types were a transverse (TR) fracture, two oblique fractures in different orientations (OB-ML: medial-lateral and OB-AP: anterior-posterior) and a "gap" fracture (GAP) without contact between the fragments. For the native femur, the most relevant areas of increased stress were located distally to the femoral head and proximally to the caudal side of the condyles. For all fracture types, the highest stresses in the implant material were present in the fracture-adjacent screws. Maximum compressive (-348 MPa) and tensile stress (197 MPa) were found for the GAP fracture, but material strength was not exceeded. The mathematical model was able to predict a load distribution in the femur of the standing horse and was used to assess the performance of internal fixation devices via FEA. The analyzed intramedullary nail and screws showed sufficient stability for all fracture types.

Luminescence of favipiravir in skin appendages and sclera. A controlled study and literature review.

BACKGROUND/OBJECTIVES: Favipiravir is an antiviral agent, recently used for COVID-19 infections. Several reports associate favipiravir intake with Wood's lamp fluorescence of hair, nails, and sclera. The present study was designed to elucidate the positivity rates, and sites of favipiravir-related fluorescence and to unravel the site-specific changes in fluorescence positivity rates by a function of time past exposure. METHODS: The study population comprised 50 patients and 50 control individuals. All patients in the patient group had received a full dose of favipiravir for COVID-19 infection. Fifty volunteers served as the control group. Wood's lamp examination was performed in a completely darkened room, and the positivity rate, extent, pattern, and distribution of fluorescence were recorded. RESULTS: Wood's light revealed fluorescence of the fingernails, toenails, sclera, and hair in 35 (70%), 35 (70%), 22 (44%), and 8 (16%) patients, respectively. No control individual tested positive by Wood's lamp. Statistical analysis revealed significant differences between patient and control groups in terms of Wood's light luminescence in the fingernails (p = .000), toenails (p = .000), sclera (p = .000) and hair (p = .003). Although fingernail, toenail, and hair fluorescence positivity rates declined or ceased at or after 91 days of favipiravir exposure, ocular fluorescence positivity rates were prolonged up to 188 days. CONCLUSIONS: These findings confirm that favipiravir may produce fluorescence of nails, sclera, and hair, detectable by Wood's light starting from the initial month and peaking at second- and third months following exposure to the medication. Although nail and hair fluorescence tend to abate after 3 months, ocular fluorescence may persist even longer than 6 months after cessation of the medication.

Inhalation exposure to toxic heavy metals in nail salon technicians and health risk assessment using Monte Carlo simulation.

OBJECTIVE: Nail salons offer a developing and diverse occupation for many women, especially the new generation. Due to the increasing apprehension surrounding heavy metals in dust caused by filing nails containing dried nail polish, the present study was designed aimed to health risk assessment of heavy metals in breathing zone of nail salon technicians (NSTs). METHODS: This is a cross-sectional study that was conducted in NSTs. The concentration of Cadmium (Cd), Lead (Pb), Nickel (Ni), Chromium (Cr) and Manganese (Mn)in breathing zone of 20 NSTs was determined using ICP-OES. RESULTS: The metal concentrations were in the following order: Mn > Pb > Ni > Cr > Cd with corresponding arithmetic mean values of0.008, 0.0023, 0.0021, 0.001 and 0.0006 mg m-3, respectively, which are exceeded the recommended levels stated in the indoor air guidelines. The average lifetime carcinogenic risk (LCR) for Cr, Cd, Ni and Pb was calculated 0.0084, 0.00054, 0.00026 and 1.44 E - 05, respectively. The LCR values of all metals (except Pb) exceeded the acceptable level set by the USEPA. The mean of Hazard quotients (HQ) for Mn, Cd, Cr, Ni and Pb were calculated to be23.7, 4.74, 2.19, 0.51 and 0.0.24, respectively. The sensitivity analysis showed that, the exposure frequency (EF) for Cr and Ni had the strong effects on generation of both LCR and HQ. Furthermore, the concentrations of Mn, Cd and Pb had strong impacts on the HQ generation and the concentration of Cd and Pb had main effects on LCR generation. CONCLUSION: To effectively reduce pollutant concentration, it is recommended to install a ventilation system near nail salon work tables and conduct continuous monitoring and quality control of nail products.

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.

Inter-observer reliability of the Onychomycosis Severity Index depending on clinical experience: A review of 50 cases.

BACKGROUND: Onychomycosis (ONM) is the most prevalent nail unit pathology, and its severity and monitoring are often based on the visual judgement of clinicians. OBJECTIVE: The objective of this study is to assess the reliability of the Onychomycosis Severity Index (OSI) classification when utilized by three clinicians with varying levels of clinical experience: an experienced podiatrist (with 5 years of experience), a moderately experienced podiatrist (with 2 years of experience) and an inexperienced podiatrist (a recent graduate familiar with the OSI classification but lacking clinical experience). Additionally, we compared the severity assessments made through visual inspection with those determined using the OSI by different clinicians. METHODS: We evaluated reliability using the intraclass correlation index (ICC), analysing 50 images of ONM. RESULTS: The OSI demonstrated a very high level of reliability (ICC: 0.889) across clinicians, irrespective of their experience levels. Conversely, a statistically significant increase in severity was observed when comparing visual assessments with the OSI (p < .001) for ONM severity evaluation. CONCLUSION: The OSI proves to be a reproducible classification system, regardless of the clinical experience of the practitioner employing it.