Precise tactile localization on the human fingernail.

Fingernails are specialized features of the primate hand, which are believed to contribute to manual dexterity. The sensorimotor functions of fingernails, however, remain poorly understood. This study investigates the ability of humans to precisely localize touches applied to the fingernail plate. Nine different locations on the fingernail were touched and participants judged the location by clicking a mouse cursor on a photograph of their finger. Performance in this condition was compared with stimuli applied to the skin of the fingertip. The results showed that participants are able to localize touch on the fingernails at substantially higher than chance levels. Moreover, the precision of this ability is not appreciably lower than that of the fingertips. These results show that the fingernail is a highly sensitive sensory organ, which is capable of providing rich spatial information about tactile stimuli.

Formulation and Antimycotic Evaluation of Colloidal Itraconazole-Loaded Metered Dose Sprays for Treating Superficial Mycoses.

Commercial topical formulations containing itraconazole (poorly water soluble), for mycotic infections, have poor penetration to infection sites beneath the nails and skin thereby necessitating oral administration. To improve penetration, colloidal solutions of itraconazole (G1-G4) containing Poloxamer 188, tween 80, ethanol, and propylene glycol were prepared and incorporated into HFA-134-containing sprays. Formulations were characterized using particle size, drug content, and Fourier-transform infrared spectroscopy (FTIR). In vitro permeation studies were performed using Franz diffusion cells for 8 h. Antimycotic activity on Candida albicans and Trichophyton rubrum was performed using broth micro-dilution and flow cytometry, while cytotoxicity was tested on HaCaT cell lines. Particle size ranged from 39.35-116.80 nm. FTIR and drug content revealed that G1 was the most stable formulation (optimized formulation). In vitro release over 2 h was 45% for G1 and 34% for the cream. There was a twofold increase in skin permeation, fivefold intradermal retention, and a sevenfold increase in nail penetration of G1 over the cream. Minimum fungicidal concentrations (MFC) against C. albicans were 0.156 and 0.313 µg/mL for G1 and cream, respectively. The formulations showed optimum killing kinetics after 48 h. MFC values against T. rubrum were 0.312 and 0.625 µg/mL for the G1 and cream, respectively. Transmission electron microscopy revealed organelle destruction and cell leakage for G1 in both organisms and penetration of keratin layers to destroy T. rubrum. Cytotoxicity evaluation of G1 showed relative safety for skin cells. The G1 formulation showed superior skin permeation, nail penetration, and fungicidal activity compared with the cream formulation.

Acute fingertip and nail injuries in the hand.

A correct diagnosis and treatment of fingertip- and nail injuries, commonly seen in the emergency room, is crucial. Insufficient treatment can result in long-term complications, including finger dysfunction and dysaesthesia, nail deformity, infection, or pain. These remaining problems may induce severe impairment of the quality of life of the patient. This review summarises the diagnosis and treatment.

Long-pulsed nd: YAG laser treatment of nail psoriasis: clinical and ultrasonographic assessment.

Nail psoriasis is a chronic, inflammatory condition which is difficult to treat, linked with greater psoriasis severity, and may be associated with anxiety and significant functional impairment of the quality of life. The 1064 nm Nd: YAG laser was reported to yield satisfactory results in the treatment of nail psoriasis.The aim of the study was to assess the clinical and ultrasonographic efficacy of long-pulsed 1064 nm Nd: YAG laser in the treatment of fingernail psoriasis and compare its effect to control fingernails.This intra-patient randomized controlled trial analyzed 86 fingernails collected from 13 patients suffering from cutaneous and nail psoriasis. The nails were randomized into two groups. Group A was treated with Nd: YAG laser once monthly for three sessions while group B served as control. Assessment took place at baseline, 1 and 3 months after the last treatment session. For scoring, the 32-points target NAPSI scoring systems was used. Additionally, two blinded dermatologists' score of improvement, patients' pain assessment by visual analogue score and ultrasonographic assessment were all performed.At the end of follow up, the medians of tNAPSI score, plate definition, matrix thickness, bed thickness and bed vascularity decreased significantly in the Nd: YAG laser treated group in comparison to baseline (p = 0.001, 0.006, 0.039, < 0.001 and 0.010, respectively). While, there was a non-significant reduction in median tNAPSI score in the control group at last follow up, however, ultrasonography recorded a significant reduction in the medians of plate definition, bed thickness and vascularity (p = 0.002, 0.011 and 0.033, respectively) from the baseline. Comparison of the Nd: YAG laser and the control groups showed no significant difference from baseline regarding the medians of tNAPSI, tNAPSI percentile improvement, pits count, blinded evaluation of photographs and ultrasonographic assessments.In conclusion, Nd: YAG laser showed clinical and ultrasonographic improvement in fingernail psoriasis. Ultrasonography is a useful noninvasive tool in diagnosing and monitoring the clinical and even the subclinical changes in nail psoriasis. Nail psoriasis although difficult to treat, may show spontaneous improvement.

A survey of the treatment and management of ingrown toenails by UK podiatrists: A cross-sectional survey.

BACKGROUND: Ingrown toenails are a common pathology. Although a range of conservative and surgical measures are widely used for this condition, little is known about their use in practice. This study explored current practice relating to the treatment or management of ingrown toenails by podiatrists in the UK. METHODS: A cross-sectional online survey (Qualtrics, Provo, UT, USA) conducted between March to June 2020 was distributed to practicing podiatrists treating or managing ingrown toenails in the UK. RESULTS: A total of 396 practicing podiatrists responded (60.1% based in the private sector). The majority (88.6%) performed nail surgery most commonly (54.3%) less than five a month. Nearly all (95%) only performed nail avulsion with or without chemical matrixectomy, universally using phenol (97.2%). Application time and number of applications varied but was most commonly applied three times (61.5%) for a total of 3 minutes (75%). Aftercare varied considerably between public and private sectors, with public sectors offering fewer follow-up appointments. CONCLUSIONS: Although there is a variation in clinical practice throughout the treatment pathway, almost all respondents offered nail avulsion with phenol matrixectomy, whereas very few provided incisional nail surgery. This data provides the most comprehensive description of how UK podiatrists conduct nail surgery for onychocryptosis.

Coxsackievirus A10 impairs nail regeneration and induces onychomadesis by mimicking DKK1 to attenuate Wnt signaling.

Coxsackievirus A10 (CV-A10) infection, a prominent cause of childhood hand-foot-and-mouth disease (HFMD), frequently manifests with the intriguing phenomenon of onychomadesis, characterized by nail shedding. However, the underlying mechanism is elusive. Here, we found that CV-A10 infection in mice could suppress Wnt/ß-catenin signaling by restraining LDL receptor-related protein 6 (LRP6) phosphorylation and ß-catenin accumulation and lead to onychomadesis. Mechanistically, CV-A10 mimics Dickkopf-related protein 1 (DKK1) to interact with Kringle-containing transmembrane protein 1 (KRM1), the CV-A10 cellular receptor. We further found that Wnt agonist (GSK3ß inhibitor) CHIR99021 can restore nail stem cell differentiation and protect against nail shedding. These findings provide novel insights into the pathogenesis of CV-A10 and related viruses in onychomadesis and guide prognosis assessment and clinical treatment of the disease.

Sensitivity, specificity, and discordance with self-report of nail sample testing for alcohol and cannabis.

BACKGROUND: Nails accumulate the alcohol metabolite, ethyl glucuronide (ETG), and the cannabis metabolite, carboxy- delta-9-THC over 3-6 months. Few studies have examined nail toxicology testing's sensitivity and specificity and the agreement between nail testing and self-reported alcohol and marijuana use. METHODS: In an ongoing clinical trial, 1101 veterans completed initial telephone questionnaires and were then asked to mail nail clippings for substance use analysis. We examined sensitivity and specificity of ETG and carboxy- delta-9-THC in nails compared to self-report of alcohol use patterns (the AUDIT-C) and substance-related harms (alcohol and THC subscales of the ASSIST). We then examined factors associated with discordance between nails and self-report. RESULTS: Almost two-thirds (707/1101) of respondents mailed in nail clippings. Those with returned nails were disproportionately married, white race, older, and less depressed. At a threshold of 8pg/mg, sensitivity was only.50 to detect risky alcohol use and.49 to detect alcohol-related issues. Sensitivity for marijuana issues was only.61. Specificity was greater than.77 for all measures. Factors associated with positive nails/negative self-report (i.e. false positives) for risky alcohol use on the Audit-C included more pain and being unmarried; false positive nails for alcohol-related issues on the ASSIST were associated with being unmarried and non-Hispanic ethnicity. False positive nails for THC-related issues on the ASSIST were associated with being African American, Hispanic, and having had legal issues. CONCLUSIONS: At standard cut-offs, nail measures had low sensitivity and higher specificity. The groups who disproportionately submit positive nails/negative self-report could have substance use patterns not adequately captured by self-report, inaccurate self-report due to social pressures, or distinct drug metabolism.

Management of an elderly patient with retention of a steel nail in the scrotum: a case report.

BACKGROUND: The retention of foreign bodies inside the body during ludic/sexual procedures or for traumatism represents one of the causes of visits to accident and emergency departments that often requires surgical removal of the foreign body. However, there are cases where the discovery of such foreign bodies takes place after many years, as in patients that are slightly compromised from a neuro-sociological point of view. CASE PRESENTATION: A 76-year-old male presented to an outpatient urological examination due to an increase in scrotal volume. At the ultrasound check, an acoustic interference from a solid object was detected, for which computed tomography was requested. The computed tomography scan revealed the presence of an elongated metal body in the perineum. The removal of the foreign body in the operating theatre was then scheduled. A 10 cm long stainless-steel nail located within an abscessed foreign body granuloma was identified and removed via a scrotal access. Four days later, a new surgical toilet was performed due to minimal necrosis of the skin flaps. The patient then performed three more dressings in the operating theatre during the following week. Healing took place by secondary intention until a perfect healing of the surgical wound was obtained. CONCLUSIONS: Removal of foreign bodies from the perineum in case of infection can be challenging. Careful attention and postoperative dressings are crucial for the success of the case.

Nailfold capillary measurements correlated to NOTCH3 R544C mutation in preclinical CADASIL patients.

BACKGROUND: Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) is a hereditary disease caused by NOTCH3 mutation. Nailfold capillaroscopy is a non-invasive technique typically used for rheumatic diseases. It has potential in other conditions linked to vascular pathology. However, capillaroscopy in CADASIL has not been explored. This study aims to investigate whether capillaroscopy measurements can correlate with brain vascular changes in preclinical CADASIL patients, specifically those with NOTCH3 mutation. METHODS: This study included 69 participants from the Taiwan Precision Medicine Initiative (TPMI) dataset who visited Taichung Veterans General Hospital from January to December 2022. All individuals underwent genetic studies, brain imaging and nailfold capillaroscopy. The Mann-Whitney U test was used to compare results of brain imaging between carriers and controls. It was also used to compare measurements in nailfold capillaroscopy within each group. Spearman Rank Correlation Analysis was used to explore the relationship between capillary measurements and brain MRI results. RESULTS: White matter hyperintensities (WMH) expression was positively correlated with capillary dimension and negatively correlated with density. Our results presented that R544C carriers exhibited a diffuse increase in WMH (p < 0.001) and a global reduction in gray matter volume but preserved in specific areas. The white matter lesion scores in all brain regions were higher in the mutation carriers than the controls. (p < 0.001). CONCLUSION: This research highlights the association of nailfold capillaroscopy findings with white matter lesions in preclinical CADASIL patients. Capillaroscopy guides an effective screening strategy in individuals with NOTCH3 mutations.

Nailfold Capillaroscopy: A Comprehensive Review on Its Usefulness in Both Clinical Diagnosis and Improving Unhealthy Dietary Lifestyles.

Since the 1970s, the utility of nailfold capillaroscopy (NFC) in diagnosing rheumatological disorders such as systemic sclerosis has been well established. Further studies have also shown that NFC can detect non-rheumatic diseases such as diabetes, glaucoma, dermatitis, and Alzheimer disease. In the past decade, nailfold capillary morphological changes have also been reported as symptoms of unhealthy lifestyle habits such as poor diet, smoking, sleep deprivation, and even psychological stress, all of which contribute to slow blood flow. Therefore, studying the relationships between the morphology of nailfold capillaries and lifestyle habits has a high potential to indicate unhealthy states or even pre-disease conditions. Simple, inexpensive, and non-invasive methods such as NFC are important and useful for routine medical examinations. The present study began with a systematic literature search of the PubMed database followed by a summary of studies reporting the assessment of morphological changes detected by NFC, and a comprehensive review of NFC's utility in clinical diagnosis and improving unhealthy dietary lifestyles. It culminates in a summary of dietary and lifestyle health promotion strategy, assessed based on NFC and other related measurements that indicate healthy microvascular blood flow and endothelial function.

Comparative analysis of the distribution and antifungal susceptibility of yeast species in cat facial hair and human nails.

Zoonotic yeast species have been implicated in disease development in both humans and cats. This study analyzed the yeast mycobiota present in feline facial hair and human nails and explored potential interspecies associations. A total of 118 biological specimens were examined, including 59 feline facial hair and 59 human nail samples. DNA extraction and DNA sequencing were performed to identify the specific yeast species. The most predominant yeast species in humans and cats were selected for antifungal susceptibility testing (itraconazole, ketoconazole, miconazole, and terbinafine). The findings unveiled diverse yeast species in cats and humans. Malassezia pachydermatis (45.8%) and Malassezia furfur (30.5%) were the most common yeast species in cats and humans, respectively. However, no significant correlation was detected between the yeast species identified in cats and their owners residing in the same household (p > 0.05). Miconazole exhibited the highest minimum inhibitory concentrations (MICs) against Malassezia pachydermatis and Malassezia furfur in both cat and human isolates, whereas terbinafine showed the lowest MICs against most Malassezia pachydermatis and Malassezia furfur in both cat and human isolates. Diverse yeast species in cat facial hair and human nails suggest possible cross-contamination among humans, pets, and environments.

Fish intake and mercury exposure in young children.

Fish consumption is one of the main sources of mercury (Hg) exposure, but few studies have examined Hg exposure from fish consumption among children. This study aimed to assess the frequency of fish intake and associations with Hg and other element concentrations among 700 three-year-old children from the New Hampshire Birth Cohort Study. Usual fish intake was derived from a validated food frequency questionnaire (Block Questionnaire for ages 2-7) and toenail element concentrations were determined using ICP-MS. Multiple linear regression analysis was used to assess the association between fish intake and toenail element concentrations. A mixture analysis, using Weighted quantile sum (WQS) regression, was used to estimate the relative contribution of fish consumption to element exposures. Twenty-three percent of children were reported to consume at least one fish meal/week on average during the previous 6 months. In adjusted linear regression models, children with any type of fish consumption versus no consumption had 108% (95% confidence interval (CI: 68%, 153%)) higher toenail Hg concentrations. To a lesser extent, children consuming "other fish (not fried) including tuna" and "fried fish or fish sticks" had 120% (95% CI: 82%, 164%), and 23% (95% CI: 2%, 51%) higher toenail concentrations, respectively, than those consuming no fish. Using WQS regression, Hg was the element most strongly related to fish consumption. Fish intake among young children was related to Hg exposure even at low levels of consumption. Future studies will need to determine the health consequences of this exposure.

Associations of a toenail metal mixture with attention and memory in the Gulf long-term follow-up (GuLF) study.

BACKGROUND: Research on metal-associated neurodegeneration has largely focused on single metals. Since metal exposures typically co-occur as combinations of both toxic and essential elements, a mixtures framework is important for identifying risk and protective factors. This study examined associations between toenail levels of an eight-metal mixture and attention and memory in men living in US Gulf states. METHODS: We measured toenail concentrations of toxic (arsenic, chromium, lead, and mercury) and essential (copper, manganese, selenium, and zinc) metals in 413 non-smoking men (23-69 years, 46 % Black) from the Gulf Long-Term Follow-Up (GuLF) Study. Sustained attention and working memory were assessed at the time of toenail sample collection using the continuous performance test (CPT) and digit span test (DST), respectively. Associations between toenail metal concentrations and performance on neurobehavioral tests were characterized using co-pollutant adjusted general linear models and Bayesian Kernel Machine Regression. RESULTS: Adjusting for other metals, one interquartile range (IQR) increase in toenail chromium was associated with a 0.19 (95 % CI: -0.31, -0.07) point reduction in CPT D Prime score (poorer ability to discriminate test signals from noise). One IQR increase in toenail manganese was associated with a 0.20 (95 % CI, -0.41, 0.01) point reduction on the DST Reverse Count (fewer numbers recalled). Attention deficits were greater among Black participants compared to White participants for the same increase in toenail chromium concentrations. No evidence of synergistic interaction between metals or adverse effect of the overall metal mixture was observed for either outcome. CONCLUSIONS: Our findings support existing studies of manganese-related memory deficits and are some of the first to show chromium related attention deficits in adults. Longitudinal study of cognitive decline is needed to verify chromium findings. Research into social and chemical co-exposures is also needed to explain racial differences in metal-associated neurobehavioral deficits observed in this study.

Child and Adolescent Manganese Biomarkers and Adolescent Postural Balance in Marietta CARES Cohort Participants.

BACKGROUND: Manganese (Mn) plays a significant role in both human health and global industries. Epidemiological studies of exposed populations demonstrate a dose-dependent association between Mn and neuromotor effects ranging from subclinical effects to a clinically defined syndrome. However, little is known about the relationship between early life Mn biomarkers and adolescent postural balance. OBJECTIVES: This study investigated the associations between childhood and adolescent Mn biomarkers and adolescent postural balance in participants from the longitudinal Marietta Communities Actively Researching Exposures Study (CARES) cohort. METHODS: Participants were recruited into CARES when they were 7-9 y old, and reenrolled at 13-18 years of age. At both time points, participants provided samples of blood, hair, and toenails that were analyzed for blood Mn and lead (Pb), serum cotinine, hair Mn, and toenail Mn. In adolescence, participants completed a postural balance assessment. Greater sway indicates postural instability (harmful effect), whereas lesser sway indicates postural stability (beneficial effect). Multivariable linear regression models were conducted to investigate the associations between childhood and adolescent Mn biomarkers and adolescent postural balance adjusted for age, sex, height-weight ratio, parent/caregiver intelligence quotient, socioeconomic status, blood Pb, and serum cotinine. RESULTS: CARES participants who completed the adolescent postural balance assessment (n=123) were 98% White and 54% female and had a mean age of 16 y (range: 13-18 y). In both childhood and adolescence, higher Mn biomarker concentrations were significantly associated with greater adolescent sway measures. Supplemental analyses revealed sex-specific associations; higher childhood Mn biomarker concentrations were significantly associated with greater sway in females compared with males. DISCUSSION: This study found childhood and adolescent Mn biomarkers were associated with subclinical neuromotor effects in adolescence. This study demonstrates postural balance as a sensitive measure to assess the association between Mn biomarkers and neuromotor function. https://doi.org/10.1289/EHP13381.

Retronychia: the importance of proper footwear.

Retronychia is commonly underdiagnosed and exhibits classic features of proximal nail fold elevation and nail plate layering. Herein we summarize the literature and discuss cause, diagnosis, and treatment of this condition.

The development of hair follicles and nail.

The hair follicle and nail unit develop and regenerate through epithelial-mesenchymal interactions. Here, we review some of the key signals and molecular interactions that regulate mammalian hair follicle and nail formation during embryonic development and how these interactions are reutilized to promote their regeneration during adult homeostasis and in response to skin wounding. Finally, we highlight the role of some of these signals in mediating human hair follicle and nail conditions.

Lgr6-expressing functional nail stem-like cells differentiated from human-induced pluripotent stem cells.

The nail matrix containing stem cell populations produces nails and may contribute to fingertip regeneration. Nails are important tissues that maintain the functions of the hand and foot for handling objects and locomotion. Tumor chemotherapy impairs nail growth and, in many cases, loses them, although not permanently. In this report, we have achieved the successful differentiation of nail stem (NS)-like cells from human-induced pluripotent stem cells (iPSCs) via digit organoids by stepwise stimulation, tracing the molecular processes involved in limb development. Comprehensive mRNA sequencing analysis revealed that the digit organoid global gene expression profile fits human finger development. The NS-like cells expressed Lgr6 mRNA and protein and produced type-I keratin, KRT17, and type-II keratin, KRT81, which are abundant in nails. Furthermore, we succeeded in producing functional Lgr6-reporter human iPSCs. The reporter iPSC-derived Lgr6-positive cells also produced KRT17 and KRT81 proteins in the percutaneously transplanted region. To the best of our knowledge, this is the first report of NS-like cell differentiation from human iPSCs. Our differentiation method and reporter construct enable the discovery of drugs for nail repair and possibly fingertip-regenerative therapy.

Relationship between nailfold videocapillaroscopic findings and cardiovascular risk factors.

BACKGROUND: Nailfold Videocapillaroscopy (NVC) is a valuable tool in the differential diagnosis of Raynaud's phenomenon (RP), present in certain Rheumatic diseases (RD). Knowing that many people have cardiovascular risk factors (CVRF), the main objective was to demonstrate that CVRF and carotid plaques produce NVC alterations. METHODS: Cross-sectional unicentric study carried out from 2020 to 2023. Four groups were formed: subjects with RD and RP, participants with RD without RP, subjects with RP without RD and finally participants without RP or RD (study group). Each subject exhibiting CVRF presented only a single risk factor. The variables collected were: sociodemographic, CVRF (diabetes, tobacco, alcohol (ALC), obesity (OBE), dyslipidemia and arterial hypertension (AH)), diseases, RP, treatments, tortuosities and NVC alterations (ramified capillaries, enlarged capillaries, giant capillaries, haemorrhages and density loss) and carotid ultrasound (CU). RESULTS: 402 subjects were included (76 % women, mean age 51 ± 16 years), 67 % had CVRF, 50 % RP and 38 % RD. Tortuosities were present in 100 % of CVRF participants. A statistically significant association was found between the presence of CVRF and all the NVC alterations: ramified capillaries (OR = 95.6), enlarged capillaries (OR = 59.2), giant capillaries (OR = 8.32), haemorrhages (OR = 17.6) and density loss (OR = 14.4). In particular, an association was found between giant capillaries with AH (p = 0,008) and OBE (p ã€ˆ0,001), and haemorrhages and density loss with ALC and OBE (p < 0,001). On the other hand, 40 subjects presented CU plaques (9.9 %), associated with enlarged capillaries (OR = 8.08), haemorrhages (OR = 4.04) and ramified capillaries (OR = 3.01). The pathological intima-media thickness was also associated with haemorrhages (OR = 3.14). CONCLUSIONS: There is a clear association between CVRF and ultrasound atherosclerotic findings in carotid with NVC alterations. These findings are of special interest for a correct NVC interpretation and to avoid false positives in the diagnosis of primary and secondary RP.