XANES spectroscopy for the clinician

XANES spectroscopy, which uses synchrotron radiation as a probe, offers substantial information about the local structure of biological samples, encompassing those without long range order such as Pt anticancer molecules, and nanometre scale or amorphous particles of calcium phosphate. Its subcellular spatial resolution, as well as its capacity to operate at room temperatures and pressures represent major advantages for medical research. Moreover, paraffin embedded biopsy samples can be analysed without any further preparation, Key publications which illustrate these capacities are presented

Chemical characterization of inks in skin reactions to tattoo

Skin reactions are well described complications of tattooing, usually provoked by red inks. Chemical characterizations of these inks are usually based on limited subjects and techniques. This study aimed to determine the organic and inorganic composition of inks using X-ray fluorescence spectroscopy (XRF), X-ray absorption spectroscopy (XANES) and Raman spectroscopy, in a cohort of patients with cutaneous hypersensitivity reactions to tattoo. A retrospective multicenter study was performed, including 15 patients diagnosed with skin reactions to tattoos. Almost half of these patients developed skin reactions on black inks. XRF identified known allergenic metals - titanium, chromium, manganese, nickel and copper - in almost all cases. XANES spectroscopy distinguished zinc and iron present in ink from these elements in endogenous biomolecules. Raman spectroscopy showed the presence of both reported (azo pigments, quinacridone) and unreported (carbon black, phtalocyanine) putative organic sensitizer compounds, and also defined the phase in which Ti was engaged. To the best of the authors' knowledge, this paper reports the largest cohort of skin hypersensitivity reactions analyzed by multiple complementary techniques. With almost half the patients presenting skin reaction on black tattoo, the study suggests that black modern inks should also be considered to provoke skin reactions, probably because of the common association of carbon black with potential allergenic metals within these inks. Analysis of more skin reactions to tattoos is needed to identify the relevant chemical compounds and help render tattoo ink composition safer.Peer reviewe

Relationship between calcinosis cutis in epidermal necrolysis and caspofungin, a physicochemical investigation

Epidermal necrolysis (EN) is a rare life-threatening condition, usually drug-induced and characterised by a diffuse epidermal and mucosal detachment. Calcinosis cutis is reported in various skin diseases, occurring preferentially with tissue damage, but has never been described in EN. Clinical, biological and histopathological characteristics of three patients were retrospectively obtained from medical charts. Immunohistochemistry of classical osteogenic markers was used to explore the pathogenesis of the calcifications; their chemical composition was determined by $\mu$Fourier transform infra-red ($\mu$FTIR) spectroscopy and their localization and morphology by field-emission scanning electron microscopy (FE-SEM). In a recent letter, part of the results of this investigation has been already presented. In this contribution, we have added original data to this previous letter. We have investigated a set of biopsies corresponding to patients who presented atypical healing retardation due to calcinosis cutis. Through FE-SEM observations at the nanometre scale, we describe different areas where are present voluminous calcifications at the surface, submicrometre spherical entities within the papillary dermis and then large “normal” fibres. FE-SEM observations show clearly that “large” calcifications are the result of an agglomeration of small spherical entities. Moreover, micrometre scale spherical entities are the results of an agglomeration of nanometer scale spherical entities. Finally, the last set of data seems to show that the starting point of the calcifications process is “distant” from the epidermis in part of the dermis which appears undamaged. Regarding the chemical composition of large calcifications, different $\mu$FTIR maps which underlined the presence of calcium-phosphate apatite have been gathered. Moreover, histopathology indicates that these pathological calcifications are not induced following a trans-differentiation of the skin cells into an osteochondrogenic phenotype. The association of caspofungin administration, known to induce in vitro intracellular calcium influx, and inflammation, induced by EN, known to favor dystrophic calcifications in various inflammatory skin diseases, could explain this never-before reported occurrence of calcinosis cutis

Relationship between calcinosis cutis in epidermal necrolysis and caspofungin, a physicochemical investigation

Epidermal necrolysis (EN) is a rare life-threatening condition, usually drug-induced and characterised by a diffuse epidermal and mucosal detachment. Calcinosis cutis is reported in various skin diseases, occurring preferentially with tissue damage, but has never been described in EN. Clinical, biological and histopathological characteristics of three patients were retrospectively obtained from medical charts. Immunohistochemistry of classical osteogenic markers was used to explore the pathogenesis of the calcifications; their chemical composition was determined by $\mu$Fourier transform infra-red ($\mu$FTIR) spectroscopy and their localization and morphology by field-emission scanning electron microscopy (FE-SEM). In a recent letter, part of the results of this investigation has been already presented. In this contribution, we have added original data to this previous letter. We have investigated a set of biopsies corresponding to patients who presented atypical healing retardation due to calcinosis cutis. Through FE-SEM observations at the nanometre scale, we describe different areas where are present voluminous calcifications at the surface, submicrometre spherical entities within the papillary dermis and then large “normal” fibres. FE-SEM observations show clearly that “large” calcifications are the result of an agglomeration of small spherical entities. Moreover, micrometre scale spherical entities are the results of an agglomeration of nanometer scale spherical entities. Finally, the last set of data seems to show that the starting point of the calcifications process is “distant” from the epidermis in part of the dermis which appears undamaged. Regarding the chemical composition of large calcifications, different $\mu$FTIR maps which underlined the presence of calcium-phosphate apatite have been gathered. Moreover, histopathology indicates that these pathological calcifications are not induced following a trans-differentiation of the skin cells into an osteochondrogenic phenotype. The association of caspofungin administration, known to induce in vitro intracellular calcium influx, and inflammation, induced by EN, known to favor dystrophic calcifications in various inflammatory skin diseases, could explain this never-before reported occurrence of calcinosis cutis

Pathologies related to abnormal deposits in dermatology : a physico-chemical approach

Although numerous pathologies are associated with abnormal skin deposits, these remain poorly described, as accurate characterization continues to present a challenge for dermatologists. Their submicrometer size as well as their diverse chemistry require various characterization tools. We aim to exemplify characterization of endogenous and exogenous skin deposits in some selected skin diseases using different physico-chemical techniques. We begin with a presentation of selected dis-eases associated with skin deposits. We then present those of our results which show their variety of structure, location and chemical composition, obtained with various tools: Field Emission Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy, X-ray fluorescence, vibra-tional spectroscopies, as well as techniques specific to synchrotron radiation. Our results constitute a real opportunity to improve diagnosis, and to understand the pathogenesis of many skin diseases, and opportunities for therapeutic intervention.Peer reviewe

Caractéristiques physico-chimiques, genèse et conséquences tissulaires des dépôts cutanés calciques

Although many dermatological pathologies are associated with pathological skin deposits, endogenous or exogenous, these remain poorly described. Their sub-micrometric size as well as their diversity of chemical composition require the use of various physico-chemical tools to allow a complete characterization. Our objective is to provide a multi-scale physico-chemical characterisation from micrometer to nanometer, but also to explore the genesis and tissue consequences of these deposits using different techniques in order to extract a clinical message. After presenting the current knowledge on these calcifying dermatoses and describing the principles of scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and vibrational spectroscopies, we present the application of these tools to four different dermatoses: calciphylaxis, calcified leg ulcers, calcinosis cutis on epidermal necrolysis and sarcoidosis. Our results show that endogenous skin deposits are mainly composed of carbapatite, whose ultrastructural appearance corresponds to phosphocalcium nanospherules aggregating to form micron-sized plaques. These deposits show a tropism towards the elastic fibres that complementary studies by multiphoton microscopy will allow to explore. These original results provide a better understanding of the physio-genesis of cutaneous calcifications, but also allow us to envisage diagnostic methods and therapeutic approaches.Bien que de nombreuses pathologies dermatologiques soient associées à des dépôts cutanés pathologiques, endogènes ou exogènes, ceux-ci restent mal décrits. Leur taille sub-micrométrique ainsi que leur diversité de composition chimique nécessitent l’utilisation de divers outils physico-chimiques pour en permettre une caractérisation complète. Notre objectif est d’apporter une caractérisation physico-chimique multi échelle du micromètre au nanomètre, mais aussi d’explorer la genèse et les conséquences tissulaires de ces dépôts en utilisant différentes techniques afin d’en extraire un message clinique. Après avoir présenté les connaissances actuelles sur ces dermatoses calcifiantes et décrit les principes de la microscopie électronique à balayage couplée à la spectroscopie de rayons X à dispersion d'énergie et des spectroscopies vibrationnelles, nous présentons l’application de ces outils à quatre dermatoses différentes : calciphylaxie, ulcères de jambe calcifiés, calcinosis cutis sur nécrolyse épidermique et sarcoïdose. L’ensemble de nos résultats montrent que les dépôts cutanés endogènes sont principalement composés de carbapatite, dont l’aspect ultra-structural correspond à des nano-sphérules phospho-calciques s’agrégeant pour former des plaques de dimension micronique. Ces dépôts présentent un tropisme vis-à-vis des fibres élastiques que des études complémentaires par microscopie multiphoton permettront d’explorer. Ces résultats originaux permettent de mieux comprendre la physio genèse des calcifications cutanées, mais également d’envisager des méthodes de diagnostic ainsi que des pistes thérapeutiques

Physico-chemical characteristics, genesis and tissue consequences of cutaneous calcium deposits

Bien que de nombreuses pathologies dermatologiques soient associées à des dépôts cutanés pathologiques, endogènes ou exogènes, ceux-ci restent mal décrits. Leur taille sub-micrométrique ainsi que leur diversité de composition chimique nécessitent l’utilisation de divers outils physico-chimiques pour en permettre une caractérisation complète. Notre objectif est d’apporter une caractérisation physico-chimique multi échelle du micromètre au nanomètre, mais aussi d’explorer la genèse et les conséquences tissulaires de ces dépôts en utilisant différentes techniques afin d’en extraire un message clinique. Après avoir présenté les connaissances actuelles sur ces dermatoses calcifiantes et décrit les principes de la microscopie électronique à balayage couplée à la spectroscopie de rayons X à dispersion d'énergie et des spectroscopies vibrationnelles, nous présentons l’application de ces outils à quatre dermatoses différentes : calciphylaxie, ulcères de jambe calcifiés, calcinosis cutis sur nécrolyse épidermique et sarcoïdose. L’ensemble de nos résultats montrent que les dépôts cutanés endogènes sont principalement composés de carbapatite, dont l’aspect ultra-structural correspond à des nano-sphérules phospho-calciques s’agrégeant pour former des plaques de dimension micronique. Ces dépôts présentent un tropisme vis-à-vis des fibres élastiques que des études complémentaires par microscopie multiphoton permettront d’explorer. Ces résultats originaux permettent de mieux comprendre la physio genèse des calcifications cutanées, mais également d’envisager des méthodes de diagnostic ainsi que des pistes thérapeutiques.Although many dermatological pathologies are associated with pathological skin deposits, endogenous or exogenous, these remain poorly described. Their sub-micrometric size as well as their diversity of chemical composition require the use of various physico-chemical tools to allow a complete characterization. Our objective is to provide a multi-scale physico-chemical characterisation from micrometer to nanometer, but also to explore the genesis and tissue consequences of these deposits using different techniques in order to extract a clinical message. After presenting the current knowledge on these calcifying dermatoses and describing the principles of scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and vibrational spectroscopies, we present the application of these tools to four different dermatoses: calciphylaxis, calcified leg ulcers, calcinosis cutis on epidermal necrolysis and sarcoidosis. Our results show that endogenous skin deposits are mainly composed of carbapatite, whose ultrastructural appearance corresponds to phosphocalcium nanospherules aggregating to form micron-sized plaques. These deposits show a tropism towards the elastic fibres that complementary studies by multiphoton microscopy will allow to explore. These original results provide a better understanding of the physio-genesis of cutaneous calcifications, but also allow us to envisage diagnostic methods and therapeutic approaches