Nail Keratin Research Articles

Is Raman Spectroscopy of Fingernails a Promising Tool for Diagnosing Systemic and Dermatological Diseases in Adult and Pediatric Populations?

Background: Raman spectroscopy is a well-known tool used in criminology, molecular biology, and histology. It is also applied to diagnose bone mineral disorders by taking advantage of the similarity of the structure of keratin and bone collagen. Raman spectroscopy can also be used in dermatology and diabetology. The purpose of the present review is to critically evaluate the available research about the use of Raman spectroscopy in the mentioned areas of medicine. Methodology: PubMed was searched for peer-reviewed articles on the subject of use of Raman spectroscopy in bone mineral disorders, dermatology, and diabetes mellitus. Results: Nail keratin and bone collagen are related structural proteins that require disulfide bond for structural stability. Therefore, Raman spectroscopy of keratin may have potential as a diagnostic tool for screening bone quality and distinguishing patients at risk of fracture for reasons different from low bone mineral density (BMD) in the adult women population. Raman spectroscopy can also investigate the changes in keratin's structure in nails affected by onychomycosis and distinguish between healthy and onychomycosis nail samples. It could also reduce the need for nail biopsy by distinguishing between dermatophytic and non-dermatophytic agents of onychomycosis. Additionally, Raman spectroscopy could expedite the diagnostic process in psoriasis (by assessing the secondary structure of keratin) and in diabetes mellitus (by examining the protein glycation level). Conclusions: In adult populations, Raman spectroscopy is a promising and safe method for assessing the structure of fingernails. However, data are scarce in the pediatric population; therefore, more studies are required in children.

Expression Profiles of Protease in Onychomycosis-Related Pathogenic Trichophyton rubrum and Tinea Capitis-Related Pathogenic Trichophyton violaceum.

The two fungal species Trichophyton rubrum and Trichophyton violaceum are common pathogens on human, infecting keratinized tissue of the outer body parts. Both species are belonging to the "Trichophyton rubrum complex" and share very high similarity in the genome. Secreted proteinases, key factors for keratin degradation, are nearly identical. Contrary, the ecological niches are differing. Trichophyton rubrum preferably infects skin and nails, whereas T. violaceum preferably infects the scalp. We postulate, that differences in the protease expression contribute to differences in ecological preferences. We analyzed the expression profiles of all 22 endoprotease genes, 12 subtilisins (S8A), 5 deuterolysins (M35) and 5 fungalysins (M36), for both species. To compare the influence of the keratin source, we designed experiments with human nail keratin, sheep wool keratin and keratin free cultivation media. Samples were taken at 12h, 24h, 48h and 96h post incubation in keratin medium. The expression of the proteases is higher in wool-keratin medium compared to human nail medium, with the exception of MEP4 and SUB6. Expression in the keratin-free medium is lowest. The expression profiles of the two species are remarkable different. The expression of MEP1, MEP3, SUB5, SUB11 and SUB12 are higher in T. rubrum compared to T. violaceum. MEP2, NpIIc, NpIIe, SUB1, SUB3, SUB4, SUB7 and SUB8 are higher expressed in T. violaceum compared to T. rubrum. The differences of the protease expression in the two species may expalin the differences in the ecological niches. Further analysis are necessary to verify the hypothesis.Please check and conform the edit made in title.Here I thinke the species of strains shouldnt be capital， and the right expression should be, "Expression Profiles of Protease in Onychomycosis-Related Pathogenic Trichophyton rubrum and Tinea Capitis-Related Pathogenic Trichophyton violaceum"Author names: Please confirm if the author names are presented accurately and in the correct se-quence (given name, middle name/initial, family name). Author 1 Given name: [Jingjing] Last name [Chen], Author 2 Given name: [Yangmin] Last name [Gao], Author 3 Given name: [Shuzhen] Last name [Xiong], Author 4 Given name: [Ping] Last name [Zhan]. Also, kindly confirm the details in the metadata are correct.YesPlease check and confirm the inserted city and country are correctly identified for affiliation 3.Please change the affiliations, Affiliation 2:²Jiangxi Provincial Clinical Research Center for Skin Diseases, Dermatology Hospital of Jiangxi Province,The Affiliated Dermatology Hospital of Nanchang University, Nanchang, 330200, Jiangxi; Affiliation 3: 3Institute of Clinical Medicine, Jiangxi Provincial People's Hospital, The First Affiliated Hospital of Nanchang Medical College,Nanchang 330001, Jiangxi. Thanks a lot!

Synthesis and characterization of proton conducting membranes based on human nail keratin and sulfonated polysulfone

Synthesis and characterization of proton conducting membranes based on human nail keratin and sulfonated polysulfone has been carried out. This research was conducted to make a proton conducting membrane based on acid-base pairs. In this study, human nail was dissolved using NaOH solvent. Through a neutralization process using glacial acetic acid, then evaporation of the solution was carried out to obtain human nail keratin. Sulfonated polysulfone composite membrane-human nail keratin was prepared in mass ratio of 3.5/0.5; 3.3/0.7; 3/1. Composite membranes were characterized by functional group analysis, XRD (X-Ray Diffraction), cation exchange capacity, degree of swelling and proton conductivity. Functional group analysis of sulfonated polysulfone-human nail keratin composite membranes showed interactions at peaks of 3000-3500 cm−1. The composite membrane has the highest cation exchange capacity, which is 2.02 meq/g on the composite membrane variation of 3/1. The greatest degree of swelling in the variation of 3/1 was 33.23%. The highest proton conductivity in the mass variation of 3/1 is 4.87 x 10−5 S/cm. The results of XRD analysis showed that the composite membrane synthesized by human nail keratin and sulfonated polysulfone had semicrystalline properties.

Physicochemical study of keratin containing impurities from human nails

The purpose of this research to study of physicochemical properties of keratin from human nails which still contains impurities. The method in this study, keratin from human nail waste was dissolved using NaOH solvent at room temperature, then neutralized to pH 7 using glacial acetic acid. On this report have studied the analysis of functional groups of keratin with impurities, viscosity, melting point, solubility and diffractogram pattern using XRD. The FTIR spectrum shows the transmittance in the wave number 1750-1200 cm−1 which is the characterization region of keratin protein. The intrinsic viscosity of nail keratin was obtained at 0.105 g/dL or 10 g/ml. The melting point of nail keratin was obtained at 210 °C. Keratin solubility test using HCl and NaOH 0.1 M and 1 M respectively, showed that keratin was soluble in strong base NaOH with high concentration. The results of XRD analysis, in a diffractogram pattern without a dominant peak and tend to widen, keratin from human nails is included in the amorphous structure type.

Synthesis and characterization of proton-conducting membranes based on bacterial cellulose and human nail keratin

Abstract In this work, proton-conducting membranes have been prepared by entrapping human nail keratin in bacterial cellulose at different mass ratios. Bacterial cellulose was obtained by fermenting coconut water with the Acetobacter xylinum bacterium, and keratin was obtained from human nails. The membrane is produced by the blending and heating process at a temperature of 40°C. FTIR spectroscopy showed the interaction between bacterial cellulose and human nail keratin at a peak area of 3,000–2,000 cm−1. The X-ray diffraction analysis has confirmed the effect of keratin mass on the diffractogram pattern of the membranes. The maximum proton conductivity has been measured as 4.572 × 10−5 S·cm−1 at 25°C and produces a degree of swelling of 32.50% for a mass ratio of bacterial cellulose/human nail keratin 4:1.

963-P: Near-Infrared Device for Diabetes Screening—ANODE01 Study

Background: Diabetes mellitus (DM) screening is currently complex, inefficient and requires resource-intensive, invasive sampling. Development of affordable, rapid, and precise mass-screening tools is valuable in identifying the millions with undiagnosed DM, especially in lower income countries. Materials and Methods: Accuracy and safety of a novel miniaturized full-spectrum near-infrared (NIR) spectroscopy device intended for DM screening was assessed in a multi-ethnic population with (n=50) or without (n=50) DM. Thirty NIR spectra scans per each middle fingernail and hand were tested for detection of dichotomised DM status based on cut-off values (< HbA1c 6.5% or 6.0 ≥) and specificity (%) of chemometrics outcomes, in assessment of glycated nail keratin versus an HbA1c point-of-care assay as control. Results: The cohort had mean age of 43.6 vs 64.4 years, 42 vs 76% females and 54 vs 68% Caucasians for non-DM and DM participants. Median (IQR) HbA1c % was 5.45 (5.2 - 5.6) and 6.8 (6.3-7.6), respectively. Clinical feasibility for NIR use was confirmed with no adverse device -related events reports for the over 6000 spectral measurements. The NIR-device demonstrated a specificity of 95.2% and 94.1% at HbA1c 6.5 and 6.0% cut-off levels, respectively (Table). Conclusions: Our preliminary results indicate high specificity and potential for clinical implementation of non-invasive NIR technology in detection of those without immediate DM risk. Disclosure P.Choudhary: Advisory Panel; Medtronic, Novo Nordisk, Dexcom, Inc., MannKind Corporation, Insulet Corporation, Research Support; Abbott Diabetes, Speaker's Bureau; Sanofi, Lilly. D.Lazaro-pacheco: Consultant; Glyconics Ltd. J.E.Salter: None. P.M.Paldanius: Consultant; Glyconics Ltd, Speaker's Bureau; Novartis. Funding Glyconics

986-P: Near-Infrared Device for Screening of Diabetes—ANODE02 Study

Background: Currently, screening for diabetes mellitus (DM) can be complex, inefficient and often resource-intensive with invasive sampling. Affordable screening tools with high specificity will be essential for smart allocation of limited healthcare resources for those in need of further diagnostics. Materials and methods: We explored the accuracy and safety of a novel compact miniaturized near-infrared (NIR) full-spectrum spectroscopy device intended for DM screening. Assessments of up to 30 NIR spectra per each middle fingernail and hand, in a cohort of people living with (n=50) or without (n=50) DM focused on detection of dichotomised DM status (< HbA1c 48 mmol/mol or 6.5% ≥) and specificity (%) based chemometrics outcomes, in assessment of glycated nail keratin versus an HbA1c point-of-care assay as control. Results: Demographics of a community primary care centre-based cohort (n=100) are presented in Table. Overall, no adverse NIR-device-related events were being reported for any of the over 6000 spectral measurements. Based on the best chemometrics model, the NIR-device demonstrated a specificity of 98.5% (95%CI 95.5 - 100.0) and 88.9% (80.5 - 97.3) at 48 and 42 mmol/mol cut-off levels, respectively, in detection of those without DM. Conclusions: Our preliminary results are indicative of high specificity and safe implementation of non-invasive NIR technology with potential for early detection and management of increasing DM risk. Disclosure F.Cos: Advisory Panel; AstraZeneca, Boehringer Ingelheim International GmbH, Abbott Diagnostics, Lilly, Novo Nordisk, Consultant; Glyconics Ltd, Menarini Group, Speaker's Bureau; AstraZeneca, Boehringer Ingelheim International GmbH, Lilly. D.Lazaro-pacheco: Consultant; Glyconics Ltd. J.E.Salter: None. P.M.Paldanius: Consultant; Glyconics Ltd, Speaker's Bureau; Novartis. Funding Glyconics

Molecular Mobility in Keratin-Rich Materials Monitored by Nuclear Magnetic Resonance: A Tool for the Evaluation of Structure-Giving Properties.

Keratins are structural proteins that are abundant in human skin, nails, and hair, where they provide mechanical strength. In the present study, we investigate the molecular mobilities and structures of three keratin-rich materials with clearly different mechanical properties: nails, stratum corneum (upper layer of epidermis), and keratinocytes (from lower layer of epidermis). We use solid-state NMR on natural-abundance 13C to characterize small changes in molecular dynamics in these biological materials with close to atomistic resolution. One strong advantage of this method is that it detects small fractions of mobile components in a molecularly complex material while it simultaneously gives information on the rigid components in the very same sample. The molecular mobility can be linked to mechanical material properties in different conditions, including hydration or exposure to osmolytes or organic solvents. Importantly, the study revealed that the response to both hydration and addition of urea is clearly different for the nail keratin compared to the stratum corneum keratin. The comparative examination of these materials may provide a better understanding of skin diseases originating from keratin malfunction and contributes to the design and development of new materials.

Extraction of Keratin from Pig Nails and Electrospinning of Keratin/Nylon6 Nanofibers for Copper (II) Adsorption.

In this study, keratins were extracted from pig nail waste via the reduction method for the first time, using L-cysteine as the reductant and urea as the lytic agent. Nylon6 and pig nail keratin were successfully combined via electrospinning to generate a series of nylon6/pig nail keratin nanofibers with a variety of keratin concentrations (0% to 8%, w/w). From the results, it was found that the best concentration was 6% (w/w). The morphologies of the electrospun nanofibers were examined via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structural properties were characterized using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), and the thermal properties were described using thermo-gravimetric analysis (TGA). These results confirmed that the nanofibers were composed of both polymeric phases. Finally, copper (II) was used as a model ion, and the nanofiber membranes exhibited a strong adsorption affinity for metal ions in the water samples. This study provides an important foundation for the application of nanofiber membranes in metal adsorption.

Simultaneous quantification of 106 drugs or their metabolites in nail samples by UPLC-MS/MS with high-throughput sample preparation: Application to 294 real cases

The nail is an alternative matrix to complement hair analysis in proving drug intake over several months in forensic toxicology investigations. However, because of the high hardness and toughness of nails, the existing pretreatment procedures for nails have the disadvantages of either a high degree of time consumption (from hours to days), or low extraction recoveries. This study aims to propose a high-throughput nail sample preparation method and provide a quantitative analytical method for 106 drugs and their metabolites present in nail. We developed cryogenic grinding, coupled with high-speed grinding in the extraction solvent method, which could improve the extraction recovery by thoroughly destroying the nail keratin for approximately 18 min. Subsequently, an ultra-high-performance liquid chromatography-tandem mass spectrometry method was developed for the identification and quantification of 34 synthetic cannabinoids, 26 fentanyls, 18 synthetic cathinones, 10 phenylethylamines, eight opioids, three phencyclidine, two tryptamines, two piperazine, cocaine, benzoylecgonine, and tetrahydrocannabinol (THC). Nail samples were collected from people with a history of drug abuse from five different regions of China. The analysis of 294 authentic samples resulted in 213 detected samples, and showed a broad concentration range including 5.04–67.26 pg/mg for nine synthetic cannabinoids, 109.29–250.29 pg/mg for a synthetic cathinone, 5.06–434291 pg/mg for four phenylethylamines, 5.06–464278 pg/mg for three phencyclidine, 5.50–192195 pg/mg for six opioids, 19.44–36.11 pg/mg for cocaine, and 50.53 pg/mg for THC in nail. Furthermore, up to 10 different compounds were detected in a single nail sample. This nail analysis method serves as a useful tool for the large-scale surveillance of illicit drugs abuse.

Nikolaus Rungius: Lifestyle and Status of an Early Seventeenth-Century Northern Finnish Vicar

Vicar Nikolaus Rungius’s (ca. 1560–1629) mummified remains have been the subject of research that has provided a wide variety of information on his life. This article examines the ways Rungius’s health and lifestyle highlight his status as a vicar, and this status is visible in his burial and funerary clothing. He was a relatively large man for his time. CT scans even include indications of certain conditions related to being overweight. Likewise, stable-isotope analyses of his nail keratin support the hypothesis that he was consuming a rather heavy, protein-rich diet. Given his status as the vicar of Kemi parish in northern Finland, he likely made sumptuous use of the rich local natural resources of fish, game, and domestic animals as part of his regular diet. In addition to his diet and health, the vicar’s high-quality clothes, while fragmentary, also open an avenue to extend the exploration of his social status and wealth.

Storing fish?: a dog\u2019s isotopic biography provides insight into Iron Age food preservation strategies in the Russian Arctic

Analysis of individual animal bodies can provide numerous useful insights in archeology, including how humans provisioned such animals, which in turn informs on a variety of other past behaviors such as human dietary patterns. In this study, we conducted stable carbon (δ13C) and nitrogen (δ15N) isotope analysis of collagen and keratin from four types of tissues from a dog burial at the Ust’-Polui site in the Iamal region of Arctic Russia. Ust’-Polui is an Iron Age site located on the Lower Ob River, a major northern fishery characterized by extreme seasonal shifts in fish presence. During a 6-month period stretching over the coldest months of the year, fish are nearly entirely absent in the Lower Ob River. Despite this, the stable isotope compositions of the dog’s bone and dentine collagen and hair and nail keratin all indicate a monotonous diet focusing on local fish. This pattern indicates the dog was provisioned year-round with fish. This was likely accomplished by mass harvesting of fish using nets or traps. Such fish were then processed and frozen for consumption during the non-fishing season. These findings suggest that people in the Ust’-Polui region also relied to some extent on fish throughout the year. Stored fish likely provided a dietary buffer for uneven returns from reindeer and bird hunting, both of which also are well-evidenced at the site.

Ciclopirox and Efinaconazole Transungual Permeation, Antifungal Activity, and Proficiency To Induce Resistance in Trichophyton rubrum.

Onychomycosis is a nail fungal infection, mostly caused by dermatophytes. The treatment efficacy is impaired by difficulties of reaching effective drug levels at the site of infection; frequent relapses occur after cessation of antifungal therapy. The aim of the study was to compare two commercial products containing ciclopirox or efinaconazole for antimycotic activity and antifungal drug resistance. A study of permeation and penetration through bovine hoof membranes, as a nail model, was performed to evaluate the antimycotic activity of permeates against clinical isolates of selected fungi, and the frequency of spontaneous in vitroTrichophyton rubrum-resistant strains was assessed by broth microdilution assays. The results suggest that ciclopirox creates a depot in the nail, leading to a gradual release of the drug over time with action on both the nail plate and bed. Conversely, efinaconazole, mildly interacting with nail keratin, mainly exerts its antifungal activity in the nail bed. However, in the case of T. rubrum, the antifungal activities of the drugs in the nail plate seem comparable. Finally, efinaconazole showed a potential for induction of resistance in T. rubrum, which may limit its efficacy over time. Ciclopirox did not show any potential to induce resistance in T. rubrum and appears endowed with a more complete activity than efinaconazole in the management of onychomycosis as the nail keratin is a substrate for the growth of fungal cells, and the availability of drug in large concentration just in the nail bed may not be sufficient to guarantee the complete eradication of pathogens.

Proximity to highways has limited influence on space use and physiology of terrestrial testudines

Transportation infrastructure is one of the mainstays of human modification of terrestrial landscapes. Turtle populations are highly affected by roads through direct mortality, contributing to population declines. However, sub-lethal effects, such as increased physiological stress, may indirectly affect turtle demographic rates, particularly in populations recently exposed to roads. We took advantage of a unique study system in southeast Ohio, where an intact forest was bisected by a four-lane highway in 2013, exposing eastern box turtles (Terrapene carolina carolina) to a new threat. The goal of this study was to evaluate ecological, physiological, and behavioral effects of exposure to a new road by comparing a roadside turtle population to a control population in a nearby roadless area, and guide mitigation on new and existing roadways. We used a unique combination of radio telemetry to assess space use, behavior, and habitat selection of turtle, and bioassay techniques to analyze chronic stress using corticosterone stored in nail keratin. We found no differences in home range sizes and habitat selection between the two sites, but roadside turtles showed strong highway avoidance, despite spending a significant amount of time in its immediate vicinity. All turtles selected for higher woody debris and understory vegetation cover, and males at both sites selected for higher canopy cover. Corticosterone concentrations from nails collected upon initial capture (2017) did not differ between the two sites, but males showed a wider range of variation. Corticosterone concentrations were significantly higher in 2018, with roadside animals showing the highest levels, but they were not correlated with home range size or proximity to highway. As such, further work is needed to evaluate indirect effects of multiple stressors on turtle endocrinology and their demographic implications, as well as the level of demographic compensation resulting from road avoidance.

Anonychia multiplex: methotrexate induced?

Psoriasis is a chronic systemic inflammatory disease primarily involving skin, nails, and articular system with associated disease-related comorbidities including type 2 diabetes mellitus and metabolic syndrome. In the past, studies had hypothesized that rapid nail growth of psoriatic nail plate with associated parakeratosis does not allow the fungus to lodge in the nail keratin, thereby the incidence of onychomycosis should have been low in nail psoriasis. However, current studies mention that psoriatic nails are predisposed to secondary onychomycosis, but the end result of manifesting as anonychia multiplex of these two coexistent nail diseases, further complicated by methotrexate, has not been reported in the literature till date. We hereby, report a case of anonychia multiplex of psoriatic nails with coexisting onychomycosis, probably induced by methotrexate-related immunosuppression, for its rarity.

Raman spectroscopy predicts the link between claw keratin and bone collagen structure in a rodent model of oestrogen deficiency

Osteoporosis is a common disease characterised by reduced bone mass and an increased risk of fragility fractures. Low bone mineral density is known to significantly increase the risk of osteoporotic fractures, however, the majority of non-traumatic fractures occur in individuals with a bone mineral density too high to be classified as osteoporotic. Therefore, there is an urgent need to investigate aspects of bone health, other than bone mass, that can predict the risk of fracture. Here, we successfully predicted association between bone collagen and nail keratin in relation to bone loss due to oestrogen deficiency using Raman spectroscopy. Raman signal signature successfully discriminated between ovariectomised rats and their sham controls with a high degree of accuracy for the bone (sensitivity 89%, specificity 91%) and claw tissue (sensitivity 89%, specificity 82%). When tested in an independent set of claw samples the classifier gave 92% sensitivity and 85% specificity. Comparison of the spectral changes occurring in the bone tissue with the changes occurring in the keratin showed a number of common features that could be attributed to common changes in the structure of bone collagen and claw keratin. This study established that systemic oestrogen deficiency mediates parallel structural changes in both the claw (primarily keratin) and bone proteins (primarily collagen). This strengthens the hypothesis that nail keratin can act as a surrogate marker of bone protein status where systemic processes induce changes.

Affinity of Luliconazole for Human Nail Derived Keratin

Affinity of Luliconazole (LLCZ), an antifungal drug used for topical treatment of onychomycosis in Japan, to nail keratin was demonstrated. Efinaconazole (EFCZ) was used as a reference drug. Drugs at fixed concentrations were added to 4 ml of buffer solution containing 40 mg of nail keratin powder prepared from healthy volunteers or from tinea unguium patients. The mixtures were shaken at 37℃, and adsorption and desorption rates of the drug in nail keratin were measured. Theoretical analysis using the Freundlich adsorption isotherm was applied to eliminate effects of testing conditions on the results. Results showed that compared with EFCZ, LLCZ exhibited high adsorption rates and low desorption rates in nail keratins. These results were verified by Freundlich analysis, in which adsorption coefficient (KadsF) and desorption coefficient (KadsF) of LLCZ were 5-7 times and about 2 times higher than EFCZ, respectively. In addition, antifungal activity against Trichophyton rubrum of the desorbed LLCZ samples was determined using disk diffusion assay. In conclusion, LLCZ is considered to possess high affinity to nail keratin. LLCZ, therefore, can be retained in the nail as a reservoir and continuously desorbed at the infection site to exhibit antifungal activity against pathogenic fungi. The pharmacokinetics of LLCZ in the nail is believed to differ from that of EFCZ. As adsorption and desorption rates of the two drugs in nail keratin tended to be different between healthy volunteers and patients, further detailed study is needed.

Biodegradation of keratin by Trichosporum loubieri RC-S6 isolated from tannery/leather waste

Keratin proteins are a major constituent of skin and its appendages including nails, hair, feathers, and wool. Keratinases are peptidases that degrade keratin. Keratinases are produced by a number of different bacterial genera as well as dermatophyte fungi. The aim of this research was to isolate and identify keratinolytic yeasts that produce enzymes that might replace some of the chemicals used during tanning in leather production. Bioprospecting/sampling targeted discarded leather scraps from chromium-polluted soil adjacent to a tannery. Isolated yeasts were selected for identification and further characterization based on their ability to hydrolyze keratin and based on zymography analyses. Yeast strain RC-S6 was putatively identified as a Trichosporon loubieri strain based on biochemical and ribosomal DNA analyses. This strain produced its highest keratinase activity on nail keratin (193.3 U ml−1). Sulfide production was observed for all keratin media types but the best substrate was human hair. T. loubieri RC-S6 secretes keratinases that degrade nails, hair, feathers and wool and degradation was faster with nail and hair keratin. The keratinases from this strain have biotechnological potential for dehairing in leather production.

Glycation in human fingernail clippings using ATR-FTIR spectrometry, a new marker for the diagnosis and monitoring of diabetes mellitus

Although HbA1c is a good diagnostic tool for diabetes, the precarity of the health system and the costs limit the use of this biomarker in developing countries. Fingernail clippings contain ±85% of keratins, which are prone to glycation. Nail keratin glycation may reflect the average glycemia over the last months. We explored if attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) can be used as a non-invasive tool for assessing glycation in diabetes. Using ATR-FTIR spectroscopy, glycation and deglycation experiments with fructosamine 3-kinase allowed to identify the spectrum that corresponds with keratin glycation in fingernail clippings. Clippings of 105 healthy subjects and 127 diabetics were subjected to the standardized ATR-FTIR spectroscopy method. In vitro glycation resulted in an increased absorption at 1047cm-1. Following enzymatic deglycation, this peak diminished significantly, proving that the AUC between 970 and 1140cm-1 corresponded with glycated proteins. Within-run CV of the assay was 3%. Storage of nail clippings at 37°C for 2weeks did not significantly change results. In diabetics, glycated nail protein concentrations (median: 1.51μmol/g protein, IQR: 1.37-1.85μmol/g protein) were significantly higher than in the controls (median: 1.19μmol/g protein, IQR: 1.09-1.26μmol/g protein) (p<0.0001). ROC analysis yielded an AUC of 0.92 at a cut-off point of 1.28μmol/g nail (specificity: 82%; sensitivity: 90%). No correlation was observed between the glycated nail protein concentrations and HbA1c. Protein glycation analysis in fingernails with ATR-FTIR spectroscopy could be an alternative affordable technique for diagnosing and monitoring diabetes. As the test does not consume reagents, and the preanalytical phase is extremely robust, the test could be particularly useful in developing countries.

Changes in nail keratin observed by Raman spectroscopy after Nd:YAG laser treatment.

Lasers and photodynamic therapy have been considered a convergence treatment for onychomycosis, which is a fungal infection on the nail bed and nail plate. Laser therapies have shown satisfactory results without significant complications for onychomycosis; however, the mechanism of clearing remains unknown. In this work, we investigated changes in the chemical structure of nail keratin induced by Nd:YAG laser using Raman spectroscopy. Toe nails with onychomycosis were treated with 1064 nm Nd:YAG laser. After laser treatment, the disulfide band (490-590 cm-1 ) of nail keratin was rarely observed or was reduced in intensity. The amide I band (1500-1700 cm-1 ) also showed changes induced by the laser. The α-helical (1652 cm-1 ) structures dominated the β-sheet (1673 cm-1 ) in nontreated nail, but the opposite phenomenon was observed after laser treatment.