Surgical interventions for ingrown toenail.

BACKGROUND: Paronychia is a prevalent clinical disease affecting the soft tissue surrounding the nails. Most cases of toenail paronychia are commonly associated with ingrown toenails. While conservative treatment is effective for mild cases of ingrown toenails, surgical intervention becomes necessary for moderate to severe cases, particularly when granulomas form. OBJECTIVE: To provide a systematic understanding of these classic and modified procedures for surgeons to select the appropriate surgical interventions for patients suffering from moderate to severe ingrown toenails and discuss this technology's advantages and limitations for dermatologic surgery. METHODS: A literature search was performed using PubMed/MEDLINE and Google Scholar databases. Studies discussing surgical intervention for ingrown toenails were included. Moreover, the surgical steps were meticulously depicted by detailed schematic diagrams. RESULTS: These surgical techniques can be divided into three categories: matrix resection, debulking of periungual soft tissues, and the rotational flap technique. Each approach possesses distinct advantages and limitations. CONCLUSION: For moderate to severe cases, surgical interventions may exhibit superior outcomes, faster recovery times, and lower recurrence rates. The surgeon must possess a comprehensive understanding and proficient skillset in various surgical techniques for ingrown toenails.

Does Electrocauterization of the Matrix After the Wedge Resection of the Toe-Nail Affect Recurrence in Discrete Age Groups Differently? A Retrospective Analysis.

The onychocryptosis, also known as ingrown toe-nails, is a painful, common disorder which is less common in children than in adults. The purpose of the present study was to focus on the effect of electrocautery matricectomy on recurrence rate and clinical outcomes in different age groups. We performed a retrospective assessment of 189 consecutive ingrown toe-nails surgeries. Electrocautery matricectomy was performed in 68 (49.2%) of 138 (73%) adults, 25 (49%) of 51 (27%) adolescents. Recurrence was observed in 11 (21.5%) adolescent patients, while recurrence was observed in 12 (8.6%) adult patients. Recurrence was observed in 9 (9.6%) of 93 patients in whom cautery was used, while 14 (14.5%) recurrences were observed in 96 patients who did not use cautery. When the adolescent patient group was evaluated separately, recurrence was observed in 2 (8%) of 25 patients in the cautery group, while recurrence was observed in 9 (34.6%) of 26 patients in the other group. EM addition to the wedge excision does not affect the results in adult patients, but it significantly reduces recurrence in adolescent patients. Especially in younger patients, it is recommended to complete the matricectomy with electrocoagulation.

Biomarkers of environmental manganese exposure.

We conducted a critical review on biomarkers of environmental manganese (Mn) exposure to answer the following questions: 1) are there reliable biomarkers of internal Mn exposure (Mn in biological matrices) associated with external metrics of Mn exposure (Mn in environmental media)? and 2) are there accurate reference values (RVs) for Mn in biological matrices? Three bibliographic databases were searched for relevant references and identified references were screened by two independent reviewers. Of the 6342 unique references identified, 86 articles were retained for data abstraction. Our analysis of currently available evidence suggests that Mn levels in blood and urine are not useful biomarkers of Mn exposure in non-occupational settings. The strength of the association between Mn in environmental media and saliva was variable. Findings regarding the utility of hair Mn as a biomarker of environmental Mn exposure are inconsistent. Measurements of Mn in teeth are technically challenging and findings on Mn in tooth components are scarce. In non-occupationally exposed individuals, bone Mn measurements using in vivo neutron activation analysis (IVNAA) are associated with large uncertainties. Findings suggest that Mn in nails may reflect Mn in environmental media and discriminate between groups of individuals exposed to different environmental Mn levels, although more research is needed. Currently, there is no strong evidence for any biological matrix as a valid biomarker of Mn exposure in non-occupational settings. Because of methodological limitations in studies aimed at derivation of RVs for Mn in biological materials, accurate RVs are scarce.

Biomarkers for occupational manganese exposure.

Long-term inhalation exposure to manganese (Mn) metal or its inorganic compounds can result in manganism or subclinical neurofunctional deficits. Studies have described affected workers in Mn dioxide mining, Mn-containing ore crushing and milling facilities, manufacturing of dry-cell batteries, Mn steel and alloy production plants, and in welders. The objective of this study was to critically review existing evidence on the reliability of potential biomarkers of Mn exposure, specifically the relationship between inhalation exposure to Mn particulates in different occupational settings and Mn concentrations in blood and other biological fluids and tissues, with a particular focus on whole blood as a potentially useful medium for measuring internal tissue dose. We also examined available evidence on the relationship between Mn levels in blood and adverse clinical and subclinical neurotoxic outcomes. Three bibliographic databases were searched for relevant studies and identified references were screened by two independent reviewers. Of the 6338 unique references identified, 76 articles were retained for data abstraction. Findings indicate that the relationships between Mn in blood and both external Mn exposure indices and neurofunctional impairments are limited and inconsistent. Different sources of exposure to Mn compounds, heterogeneity in the methodological approaches, and inadequate reporting of essential information limited direct comparison of the reported findings. Among the Mn-exposure biomarkers considered in this review - including biomarkers in blood, plasma, serum, erythrocytes, urine, bone, toenails, fingernails, hair, saliva - biomarkers in whole blood may provide to be most useful in Mn biomonitoring and risk assessment.

Toenail speciation biomarkers in arsenic-related disease: a feasibility study for investigating the association between arsenic exposure and chronic disease.

Long-term exposure to environmental arsenic has been associated with many chronic diseases, including several cancers, and diabetes. Urinary studies have implicated arsenic speciation as an important risk factor, however, such associations have not been replicated using toenail samples: a relatively new biosample for estimating long-term internal dose-exposure to arsenic. Despite having several advantages over conventional biosamples such as ease of collection and storage, standard methods for arsenic speciation analysis in toenails have not yet been established. The primary objectives of this study were to 1) establish an analytical method for arsenic speciation analysis in toenails, 2) describe preliminary arsenic speciation profiles of toenail samples from individuals with skin, lung, bladder, and kidney cancer, type II diabetes, and no known disease, and 3) determine if these speciation patterns differ between disease groups to inform the feasibility of subsequent research. A small cross-sectional feasibility study was carried out using 60 toenail samples and baseline questionnaire data from the Atlantic Partnership for Tomorrow's Health (Atlantic PATH) study. Arsenic speciation profiles were determined using high performance liquid chromatography (HPLC) paired with inductively coupled plasma-mass spectrometry (ICP-MS). While no differences in total arsenic were found, arsenic speciation profiles were significantly different between certain cancer groups and the reference group with no known disease. Specifically, the percentage of monomethylarsonic acid (%MMA) was found to be significantly higher in the toenails of individuals with lung cancer and kidney cancer, compared to healthy individuals with similar total arsenic exposure. To the best of our knowledge, this is the first study to describe arsenic speciation patterns in individuals with several arsenic-related diseases using toenails: a convenient, non-invasive, biobankable sample capable of longer-term exposure estimation than conventional biosamples. These preliminary data provide evidence that toenail arsenic speciation patterns differ between groups with arsenic-related disease, and those with no known disease. Toenail arsenic speciation analysis is feasible and could potentially have important implications for research on arsenic-related diseases. Further investigation is warranted and would benefit from including detailed arsenic exposure data to explore the observed heterogeneity in arsenic speciation profiles.

Winograd surgery can be performed under partial digital block in patients with ingrown toenails.

BACKGROUND: Winograd procedures performed under a partial digital block with a single needle to the surgical side instead of the entire toe were not evaluated. This study aimed to examine the clinical results of classic ring block and partial digital block performed during Winograd procedures in cases of ingrown toenails. METHODS: A total of 210 patients underwent Winograd surgery were divided into two groups according to the type of anesthesia used as follows: traditional ring block (TRB) and partial digital block (PDB). Visual analog scale (VAS) scores, Heifetz stage patient satisfaction levels, recurrence rates, and need for reoperation were recorded. RESULTS: Compared with the PDB group, the during operation VAS score was statistically significantly higher in the TRB group (p = 0001). There was no statistically significant difference between the groups in terms of postoperative satisfaction, recurrence (p = 0294), and reoperation rates (p = 0651). CONCLUSIONS: This study is the first to show that adequate anesthetic efficacy can be achieved with a less invasive intervention for Winograd procedures.

An adult Chinese patient with developmental delay with short stature, dysmorphic features, and sparse hair (Loucks-Innes syndrome).

Variants of the diphthamide biosynthesis I (DPH1, OMIM*603527) are associated with developmental delay, short stature, and sparse hair syndrome (DEDSSH/DPH1 syndrome) (OMIM# 616901). Another name is Loucks-Innes syndrome. DPH1 syndrome is an ultrarare and severe neurodevelopmental disorder. Less than 20 patients were reported from different ethnicities. Here, we described the first Chinese adult with genetically confirmed DPH1 syndrome. We summarized previously reported patients in the literature and found that developmental delay, unusual skull shape, sparse hair, and facial dysmorphism were consistently present in all DPH1 syndrome patients. Dysplastic toenails and dental abnormalities are age-dependent characteristics of DPH1 syndrome. Our patient was the first reported patient with documented growth hormone deficiency. Dental and endocrine checkup should be considered in the routine follow-up of DPH1 syndrome patients.

Portable X-ray Fluorescence as a Rapid Determination Tool to Detect Parts per Million Levels of Ni, Zn, As, Se, and Pb in Human Toenails: A South India Case Study.

Chronic exposure to inorganic pollutants adversely affects human health. Inductively coupled plasma mass spectrometry (ICP-MS) is the most common method used for trace metal(loid) analysis of human biomarkers. However, it leads to sample destruction, generation of secondary waste, and significant recurring costs. Portable X-ray fluorescence (XRF) instruments can rapidly and nondestructively determine low concentrations of metal(loid)s. In this work, we evaluated the applicability of portable XRF as a rapid method for analyzing trace metal(loid)s in toenail samples from three populations (n = 97) near the city of Chennai, India. A Passing-Bablok regression analysis of results from both methods revealed that there was no proportional bias among the two methods for nickel (measurement range ∼25 to 420 mg/kg), zinc (10 to 890 mg/kg), and lead (0.29 to 4.47 mg/kg). There was a small absolute bias between the two methods. There was a strong proportional bias (slope = 0.253, 95% CI: 0.027, 0.614) between the two methods for arsenic (below detection to 3.8 mg/kg) and for selenium when the concentrations were lower than 2 mg/kg. Limits of agreement between the two methods using Bland-Altman analysis were derived for nickel, zinc, and lead. Overall, a suitably calibrated and evaluated portable XRF shows promise in making high-throughput assessments at population scales.

Comparison of Chemical Matricectomy with Trichloroacetic Acid, Phenol, or Sodium Hydroxide for Ingrown Toenails: A Systematic Review and Network Meta-Analysis.

is missing (Short communication).

Using human hair and nails as biomarkers to assess exposure of potentially harmful elements to populations living near mine waste dumps.

Potentially harmful elements (PHEs) manganese (Mn), cobalt (Co), copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn) were measured in human hair/nails, staple crops and drinking water to ascertain the level of exposure to dust transference via wind and rain erosion for members of the Mugala community living near a mine waste dump in the Zambian Copperbelt. The mean PHE concentrations of hair in decreasing order were Zn (137 ± 21 mg/kg), Cu (38 ± 7 mg/kg), Mn (16 ± 2 mg/kg), Pb (4.3 ± 1.9 mg/kg), Ni (1.3 ± 0.2 mg/kg) and Cr (1.2 ± 0.2 mg/kg), Co (0.9 ± 0.2 mg/kg) and Cd (0.30 ± 0.02 mg/kg). Whilst for toenails the decreasing order of mean concentrations was Zn (172 ± 27 mg/kg), Cu (30 ± 5 mg/kg), Mn (12 ± 2 mg/kg), Pb (4.8 ± 0.5 mg/kg), Ni (1.7 ± 0.14 mg/kg) and Co (1.0 ± 0.02 mg/kg), Cr (0.6 ± 0.1 mg/kg) and Cd (0.1 ± 0.002 mg/kg). The concentration of these potentially harmful elements (PHEs) varied greatly among different age groups. The results showed that Mn, Co, Pb, Cd and Zn were above the interval values (Biolab in Nutritional and environmental medicine, Hair Mineral Analysis, London, 2012) at 0.2-2.0 mg/kg for Mn, 0.01-0.20 mg/kg for Co, < 2.00 mg/kg for Pb, < 0.10 mg/kg for Cd and 0.2-2.00 mg/kg for Zn, whilst Ni, Cu and Cr concentrations were within the normal range concentrations of < 1.40 mg/kg, 10-100 mg/kg and 0.1-1.5 mg/kg, respectively. Dietary intake of PHEs was assessed from the ingestion of vegetables grown in Mugala village, with estimated PHE intakes expressed on a daily basis calculated for Mn (255), Pb (48), Ni (149) and Cd (33) µg/kg bw/day. For these metals, DI via vegetables was above the proposed limits of the provisional tolerable daily intakes (PTDIs) (WHO in Evaluation of certain food additive and contaminants, Seventy-third report of the Joint FAO/WHO Expert Committee on Food Additives, 2011) for Mn at 70 µg/kg bw/day, Pb at 3 µg/kg bw/day, Ni and Cd 5 µg/kg bw/day and 1 µg/kg bw/day, respectively. The rest of the PHEs listed were within the PTDIs limits. Therefore, Mugala inhabitants are at imminent health risk due to lead, nickel and cadmium ingestion of vegetables and drinking water at this location.

Toenail Metal Exposures in Fishermen from Bodo City, Nigeria.

We conducted exposure assessment using toenails from 20 fishermen living in Bodo City, a community of the Niger delta region in Nigeria. This community has been affected by over 4000 oil spills and environmental disasters. Fishing is the primary source of food and income for individuals in this community. Previous research in Bodo City found elevated metal levels in fish. Toenails were used as a biomarker to investigate the feasibility for use in risk assessment studies in developing countries. The toenails collected had significantly higher manganese levels (median 5.8 µg/g) and lead levels (median 0.98 µg/g) than those reported in more developed countries, comparable levels to those from other low-middle incomes countries. These exposure levels are likely a direct result of exposures from the environmental disasters the community has experienced and would be related to increased risks for many diseases previously associated with heavy metal exposures.

Toenail-Based Metal Concentrations and Young-Onset Breast Cancer.

Several metals have carcinogenic properties, but their associations with breast cancer are not established. We studied cadmium, a metalloestrogen, and 9 other metals-arsenic, cobalt, chromium, copper, mercury, molybdenum, lead, tin, and vanadium--in relation to young-onset breast cancer (diagnosis age <50 years), which tends to be more aggressive than and have a different risk profile from later-onset disease. Recent metal exposure was measured by assessing element concentrations, via inductively coupled plasma mass spectrometry, in toenail clippings of 1,217 disease-discordant sister pairs in the US-based Sister (2003-2009) and Two Sister (2008-2010) studies. Conditional logistic regression was used to calculate odds ratios and 95% confidence intervals. After correcting for differential calendar time of sample collection, no statistically significant associations were observed between any metals and breast cancer. Vanadium had the largest odds ratio (for fourth vs. first quartile, odds ratio = 1.54, 95% confidence interval: 0.75, 3.16; P for trend = 0.21). The association between cadmium and young-onset breast cancer was near null, with no evidence of a dose-response relationship (for fourth vs. first quartile, odds ratio = 0.95, 95% confidence interval: 0.64, 1.43; P for trend = 0.64). Positive associations between urinary cadmium concentrations and breast cancer have been reported in case-control studies, but we observed no such association between young-onset breast cancer and toenail concentrations of any assessed metals.

Toenail-Based Metal Concentrations and Young-Onset Breast Cancer.

Several metals have carcinogenic properties, but their associations with breast cancer are not established. We studied cadmium, a metalloestrogen, and 9 other metals-arsenic, cobalt, chromium, copper, mercury, molybdenum, lead, tin, and vanadium--in relation to young-onset breast cancer (diagnosis age <50 years), which tends to be more aggressive than and have a different risk profile from later-onset disease. Recent metal exposure was measured by assessing element concentrations, via inductively coupled plasma mass spectrometry, in toenail clippings of 1,217 disease-discordant sister pairs in the US-based Sister (2003-2009) and Two Sister (2008-2010) studies. Conditional logistic regression was used to calculate odds ratios and 95% confidence intervals. After correcting for differential calendar time of sample collection, no statistically significant associations were observed between any metals and breast cancer. Vanadium had the largest odds ratio (for fourth vs. first quartile, odds ratio = 1.36, 95% confidence interval: 0.84, 2.21; P for trend = 0.17). Cadmium was associated with a small increase in risk, with no evidence of a dose-response relationship (for fourth vs. first quartile, odds ratio = 1.15, 95% confidence interval: 0.82, 1.60; P for trend = 0.67). Positive associations between urinary cadmium concentrations and breast cancer have been reported in case-control studies, but we observed no such association between young-onset breast cancer and toenail concentrations of any assessed metals.

A Randomized, Double-Blind, Controlled Trial Evaluating the Efficacy of Nd:YAG 1064 nm Short-Pulse Laser Compared With Placebo in the Treatment of Toenail Onychomycosis.

INTRODUCTION: Laser and light-based therapies have emerged as interesting treatment options with minimal side effects or contraindications to treat onychomycosis. Although increasing reports of successful treatment exist, few randomized, controlled, prospective studies have evaluated their true efficacy. We conducted a prospective, randomized, double-blind, controlled trial to evaluate the cure rate of onychomycosis treated by laser. METHODS: Fifty-one patients were randomized to receive 3 treatments (0, 12, 24 weeks) of 1064 Nd:YAG short-pulse (Cutera GenesisPlus) laser or placebo sham laser. The primary efficacy end point is the proportion of patients with a complete cure rate of the target great toenail at week 52. The secondary efficacy end points, at week 52, were treatment success defined as almost clear nail (≤ 10%) and negative mycology, completely or almost clear nail of the great toenail, negative mycology, improvement from one OSI severity class to another of the target toenail, and the difference in proximal nail plate clearance between baseline and week 52. RESULTS: No patient (0%) in the laser group and 2 patients (7.7%) in the placebo group reached the primary outcome. One patient (4.8%) in the laser group reached treatment success vs 2 (7.7%) in the placebo group. Only 6 patients (33%) had negative cultures in the laser group vs 11 (50%) in the placebo group. None of the secondary end points were met. CONCLUSIONS: This study demonstrated that 3 treatments of Nd:YAG 1064 nm laser at 3-month intervals were not effective to treat onychomycosis.

Manganese in toenails is associated with hearing loss at high frequencies in humans.

PURPOSE: Elevated hearing thresholds from high frequencies are known to be one of the hallmarks of age-related hearing loss. Our recent study showed accumulation of manganese (Mn) in inner ears resulting in acceleration of age-related hearing loss in mice orally exposed to Mn. However, there is no evidence showing an association between Mn in non-invasive biological samples and hearing loss in humans evaluated by pure tone audiometry (PTA). In this study, we evaluated Mn in non-invasive biological samples as a possible biomarker for hearing loss in humans. MATERIALS AND METHODS: We determined hearing levels by PTA and Mn levels in toenails, hair and urine with an inductively coupled plasma mass spectrometer (ICP-MS) in 145 healthy subjects in Bangladesh. RESULTS: Multivariable analyses showed that Mn levels in toenails, but not in hair and urine samples, were significantly associated with hearing loss at 8 kHz and 12 kHz. Moreover, our experimental study showed a significant correlation between Mn levels in inner ears and nails, but not hair, in mice orally exposed to Mn. CONCLUSIONS: The results provide novel evidence that Mn in toenails is a possible biomarker for hearing loss at high frequencies in humans.

Biological and behavioral factors modify urinary arsenic metabolic profiles in a U.S. population.

BACKGROUND: Because some adverse health effects associated with chronic arsenic exposure may be mediated by methylated arsenicals, interindividual variation in capacity to convert inorganic arsenic into mono- and di-methylated metabolites may be an important determinant of risk associated with exposure to this metalloid. Hence, identifying biological and behavioral factors that modify an individual's capacity to methylate inorganic arsenic could provide insights into critical dose-response relations underlying adverse health effects. METHODS: A total of 904 older adults (≥45 years old) in Churchill County, Nevada, who chronically used home tap water supplies containing up to 1850 µg of arsenic per liter provided urine and toenail samples for determination of total and speciated arsenic levels. Effects of biological factors (gender, age, body mass index) and behavioral factors (smoking, recent fish or shellfish consumption) on patterns of arsenicals in urine were evaluated with bivariate analyses and multivariate regression models. RESULTS: Relative contributions of inorganic, mono-, and di-methylated arsenic to total speciated arsenic in urine were unchanged over the range of concentrations of arsenic in home tap water supplies used by study participants. Gender predicted both absolute and relative amounts of arsenicals in urine. Age predicted levels of inorganic arsenic in urine and body mass index predicted relative levels of mono- and di-methylated arsenic in urine. Smoking predicted both absolute and relative levels of arsenicals in urine. Multivariate regression models were developed for both absolute and relative levels of arsenicals in urine. Concentration of arsenic in home tap water and estimated water consumption were strongly predictive of levels of arsenicals in urine as were smoking, body mass index, and gender. Relative contributions of arsenicals to urinary arsenic were not consistently predicted by concentrations of arsenic in drinking water supplies but were more consistently predicted by gender, body mass index, age, and smoking. CONCLUSIONS: These findings suggest that analyses of dose-response relations in arsenic-exposed populations should account for biological and behavioral factors that modify levels of inorganic and methylated arsenicals in urine. Evidence of significant effects of these factors on arsenic metabolism may also support mode of action studies in appropriate experimental models.

What do the trace metal contents of urine and toenail samples from Qatar׳s farm workers bioindicate?

Qatar׳s farm workers provide a unique population for exposure study: they are young, healthy males. This study combined trace element profiles in urine and toenail with survey information from 239 farm workers to assess the extent to which the biomarkers provide complementary exposure information. Urinary Mo levels (average=114 µg/L) were elevated; average urinary values (µg/L) for all other elements were: V (1.02), Cr (0.55), Mn (2.15), Fe (34.1), Co (0.47), Ni (2.95), Cu (15.0), As (47.8), Se (25.7), Cd (1.09), Ba (22.5), Pb (2.50) and U (0.15). Average toenail concentrations (mg/kg) were: Mn (2.48), Cu (4.43), As (0.26), Se (0.58), Mo (0.07), Cd (0.03), Ba (1.00), Pb (0.51) and U (0.02). No significant association was found between corresponding elements in urine and toenails. Elemental profiles suggest groundwater (with the exception of Mo) and soil-dust-crop exposure pathways cannot account for elemental variations. The main factors moderating trace element contents are related to depuration processes involving participants׳ trace element body burden prior to work in Qatar, and interactions of trace element metabolic cycles which over-ride the exposure footprint. Toenail and urine need to be carefully validated before reliable use as biomarkers of exposure in general populations for most elements in the study.

A review of lasers and light for the treatment of onychomycosis.

BACKGROUND AND OBJECTIVE: Onychomycosis is a common fungal infection that affects many individuals. Systemic therapies are effective, but are limited by their side effects and potential for hepatotoxicity. Topical therapies have less serious side effects, yet provide only limited efficacy due to their inability to penetrate the nail plate. These limitations have led to the investigation of laser and light-based modalities as alternative treatment options for onychomycosis. This article will provide an overview and critical assessment of the field of laser and other energy-based treatments for onychomycosis. STUDY DESIGN/MATERIALS AND METHODS: A literature search was conducted on laser and light-based treatments for onychomycosis. RESULTS: Early data are promising, however, many of these studies are small or poorly designed. CONCLUSION: Further evaluation and larger studies are needed to determine the optimal light source, pulse duration, and treatment schedule for long-term success.

Do toenail manganese and iron levels reflect brain metal levels or brain metabolism in welders?

Inhalation of welding fumes can cause metal accumulation in the brain, leading to Parkinsonian-like symptoms. Metal accumulation and altered neurochemical profiles have been observed using magnetic resonance imaging (MRI) in highly exposed welders, being associated with decreased motor function and cognition. While MRI is impractical to use as a health risk assessment tool in occupational settings, toenail metal levels are easier to assess and have been demonstrated to reflect an exposure window of 7-12 months in the past. Yet, it is unclear whether toenail metal levels are associated with brain metal levels or changes in metabolism, which are the root of potential health concerns. This study investigates whether toenail manganese (Mn) and iron (Fe) levels, assessed at several time points, correlate with brain Mn and Fe levels, measured by MRI, as well as brain GABA, glutamate (Glu), and glutathione (GSH) levels, measured by Magnetic Resonance Spectroscopy (MRS), in seventeen Mn-exposed welders. Quantitative T1 and R2* MRI maps of the whole brain, along with GABA, Glu, and GSH MRS measurements from the thalamus and cerebellum were acquired at baseline (T0). Toenail clippings were collected at T0 and every three months after the MRI for a year to account for different exposure periods being reflected by toenail clippings and MRI. Spearman correlations of toenail metal levels were run against brain metal and metabolite levels, but no significant associations were found for Mn at any timepoint. Cerebellar GSH positively correlated with toenail Fe clipped twelve months after the MRI (p = 0.05), suggesting an association with Fe exposure at the time of the MRI. Neither thalamic GABA nor Glu correlated with toenail Fe levels. In conclusion, this study cannot support toenail Mn as a proxy for brain Mn levels or metabolic changes, while toenail Fe appears linked to brain metabolic alterations, underscoring the importance of considering other metals, including Fe, in studying Mn neurotoxicity.

Assessment of Essential and Toxic Element Levels in the Toenails of Children with Autism Spectrum Disorder.

Autism spectrum disorder (ASD) has become a global public health concern, impacting the quality of life. The question of gene-environment interaction in the emergence of ASD remains a subject of ongoing debate, and exploring its pathophysiology is thoroughly related to metals as a risk factor. Therefore, this study aims to assess the levels of toxic (Al, Cd, Hg, and Pb) and essential (Cr, Mn, Fe, Ni, Cu, Zn, and Se) elements in toenail samples collected in children with ASD and neurotypical children, by ICP-MS. Parallelly, we will discuss the use of toenails as an exposure indicator. The study involved 208 children aged 3 to 14 from Marrakech, Morocco. One hundred two were diagnosed with ASD and 106 were neurotypical children. Significant statistical differences in the concentration of Cr, Mn, and Fe were documented between the two groups. Higher levels of Pb in toenails compared to reference values have been reported. No association was established between concentrations of elements and age. Spearman correlation coefficients revealed a significantly different pattern of mutual dependence for toxic and essential elements between the two groups. The strongest positive correlations were found in the neurotypical group (Fe-Mn (ρ = 0.750), and Se-Zn (ρ = 0.800)). These results provide additional, although inconclusive, evidence on the probable role of element disturbance in the pathogenesis of ASD. Further studies should be performed to explore other nutritional, cultural, sociodemographic, environmental, and methodological factors that may impact the levels of these elements in the nails and their possible correlation with the incidence of ASD.