Manganese-cobalt geomimetic materials for supercapacitor electrode

A manganese-cobalt asbolane material synthesized by low-temperature cationic exchange from birnessite in cobalt nitrate solution has been comprehensively characterized and tested for the first time as a massive (with high active mass loading) positive electrode material for to asymmetric aqueous supercapacitors. The structure of this Mn-rich material, which is homologous to the natural asbolanes well known by mineralogists, consists of MnO2-type slabs with partial substitution of Co3+ for Mn; the slabs alternate with Co(OH)2 islands located in the interlayer spacing. This structural arrangement was confirmed through in-depth electronic transmission microscopy analyses, which reveal two interlocking hexagonal sublattices with distinct a lattice-cell parameters but identical c parameters. The electrochemical performance of this geomimetic phase in alkaline electrolytes is highly promising, with specific capacitance of up to 180 F g-1 at moderate current densities and 94 F g-1 at 10 A g-1. Investigation into the charge storage mechanisms indicates effective synergy between the pseudocapacitive properties of the MnO2 slabs and the Co(OH)2 islands, in which protonic conduction is suspected to play a key role. Additionally, long-term cycling and calendar aging tests suggest that the interlayer cobalt gradually migrates to the metal oxide layer upon cycling while maintaining excellent energy storage performance. This study clearly underscores the value of exploring geomimetic minerals as potential electrode materials for energy storage applications.

Impact of Anionic Ordering on the Iron Site Distribution and Valence States in Oxyfluoride Sr2FeO3+xF1-x (x = 0.08, 0.2) with a Layered Perovskite Network

Sr₂FeO₃F, an oxyfluoride compound with an n = 1 Ruddlesden-Popper structure, was identified as a potential interesting mixed ionic and electronic conductor (MIEC). The phase can be synthesized under a range of different pO₂ atmospheres, leading to various degrees of fluorine for oxygen substitution and Fe⁴⁺ content. A structural investigation and thorough comparison of both argon- and air-synthesized compounds were performed by combining high-resolution X-ray and electron diffraction, high-resolution scanning transmission electron microscopy, Mössbauer spectroscopy, and DFT calculations. While the argon-synthesized phase shows a well-behaved O/F ordered structure, this study revealed that oxidation leads to averaged large-scale anionic disorder on the apical site. In the more oxidized Sr₂FeO_3.2F_0.8 oxyfluoride, containing 20% of Fe⁴⁺, two different Fe positions can be identified with a 32%/68% occupancy (P4/nmm space group). This originates due to the presence of antiphase boundaries between ordered domains within the grains. Relations between site distortion and valence states as well as stability of apical anionic sites (O vs F) are discussed. This study paves the way for further studies on both ionic and electronic transport properties of Sr₂FeO_3.2F_0.8 and its use in MIEC-based devices, such as solid oxide fuel cells.

Composite Mn-Co electrode materials for supercapacitors: why the precursor's morphology matters!

In the energy storage field, an electrode material must possess both good ionic and electronic conductivities to perform well, especially when high power is needed. In this context, the development of composite electrode materials combining an electrochemically active and good ionic conductor phase with an electronic conductor appears as a perfectly adapted approach to generate a synergetic effect and optimize the energy storage performance. In this work, three layered MnO₂ phases with various morphologies (veils, nanoplatelets and microplatelets) were combined with electronic conductor cobalt oxyhydroxides with different platelet sizes (∼20 nm vs. 70 nm wide), to synthesize 6 different composites by exfoliation and restacking processes. The influence of precursors' morphology on the distribution of the Mn and Co objects within the composites was carefully investigated and correlated with the electrochemical performance of the final restacked material. Overall, the best performing restacked composite was obtained by combining MnO₂ possessing a veil morphology with the smallest cobalt oxyhydroxide nanoplatelets, leading to the most homogeneous distribution of the Mn and Co objects at the nanoscale. More generally, the aim of this work is to understand how the size and morphology of the precursor building blocks influence their distribution homogeneity within the final composite and to find the most compatible building blocks to reach a homogeneous distribution at the nanoscale.

Reactivity at the Electrode-Electrolyte Interfaces in Li-Ion and Gel Electrolyte Lithium Batteries for LiNi0.6Mn0.2Co0.2O2 with Different Particle Sizes

The layered oxide LiNi_0.6Mn_0.2Co_0.2O₂ is a very attractive positive electrode material, as shown by the good reversible capacity, chemical stability, and cyclability upon long-range cycling in Li-ion batteries and, hopefully, in the near future, in all-solid-state batteries. Three samples with variable primary particle sizes of 240 nm, 810 nm, and 2.1 μm on average and very similar structures close to the ideal 2D layered structure (less than 2% Ni²⁺ ions in Li⁺ sites) were obtained by coprecipitation followed by a solid-state reaction at high temperatures. The electrochemical performances of the materials were evaluated in a conventional organic liquid electrolyte in Li-ion batteries and in a gel electrolyte in all-solid-state batteries. The positive electrode/electrolyte interface was analyzed by X-ray photoelectron spectroscopy to determine its composition and the extent of degradation of the lithium salt and the carbonate solvents after cycling, taking into account the changes in particle size of the positive electrode material and the nature of the electrolyte.

Sarilumab in adults hospitalised with moderate-to-severe COVID-19 pneumonia (CORIMUNO-SARI-1): An open-label randomised controlled trial

Background

Patients with COVID-19 pneumonia can have increased inflammation and elevated cytokines, including interleukin (IL)-6, which might be deleterious. Thus, sarilumab, a high-affinity anti-IL-6 receptor antibody, might improve the outcome of patients with moderate-to-severe COVID-19 pneumonia.

Methods

We did a multicentric, open-label, Bayesian randomised, adaptive, phase 2/3 clinical trial, nested within the CORIMUNO-19 cohort, to test a superiority hypothesis. Patients 18 years or older hospitalised with COVID-19 in six French centres, requiring at least 3L/min of oxygen but without ventilation assistance and a WHO Clinical Progression Scale [CPS] score of 5 were enrolled. Patients were randomly assigned (1:1) via a web-based system, according to a randomisation list stratified on centre and with blocks randomly selected among 2 and 4, to receive usual care plus 400 mg of sarilumab intravenously on day 1 and on day 3 if clinically indicated (sarilumab group) or usual care alone (usual care group). Primary outcomes were the proportion of patients with WHO-CPS scores greater than 5 on the 10-point scale on day 4 and survival without invasive or non-invasive ventilation at day 14. This completed trial is closed to new participants and is registered with ClinicalTrials.gov, NCT04324073.

Findings

165 patients were recruited from March 27 to April 6, 2020, and 148 patients were randomised (68 patients to the sarilumab group and 80 to the usual care group) and followed up for 90 days. Median age was 61·7 years [IQR 53·0–71·1] in the sarilumab group and 62·8 years [56·0–71·7] in the usual care group. In the sarilumab group 49 (72%) of 68 were men and in the usual care group 59 (78%) of 76 were men. Four patients in the usual care group withdrew consent and were not analysed. 18 (26%) of 68 patients in the sarilumab group had a WHO-CPS score greater than 5 at day 4 versus 20 (26%) of 76 in the usual care group (median posterior absolute risk difference 0·2%; 90% credible interval [CrI] −11·7 to 12·2), with a posterior probability of absolute risk difference greater than 0 of 48·9%. At day 14, 25 (37%) patients in the sarilumab and 26 (34%) patients in the usual care group needed ventilation or died, (median posterior hazard ratio [HR] 1·10; 90% CrI 0·69–1·74) with a posterior probability HR greater than 1 of 37·4%. Serious adverse events occurred in 27 (40%) patients in the sarilumab group and 28 (37%) patients in the usual care group (p=0·73).

Interpretation

Sarilumab treatment did not improve early outcomes in patients with moderate-to-severe COVID-19 pneumonia. Further studies are warranted to evaluate the effect of sarilumab on long-term survival.

Funding

Assistance publique—Hôpitaux de Paris

Therapeutic prevention of COVID-19 in elderly: a case-control study

COVID-19 is a particularly aggressive disease for the elderly as 86% of deaths related to COVID-19 occur in people over 65 years of age. Despite the urgent need for a preventive treatment, there are currently no serious leads, other than the vaccination. The aim of this retrospective case-control study is to find a pharmacological preventive treatment of COVID-19 in elderly patients. One-hundred-seventy-nine patients had been in contact with other COVID-19 patients at home or in hospital, of whom 89 had tested RT-PCR-positive (COVID-pos) for the virus and 90 had tested RT-PCR-negative (COVID-neg). Treatments within 15 days prior to RT-PCR (including antihypertensive drugs, antipsychotics, antibiotics, nonsteroidal anti-inflammatory drugs, proton pump inhibitors (PPIs), oral antidiabetics (OADs), corticosteroids, immunosuppressants), comorbidities, symptoms, laboratory values, and clinical outcome were all collected. COVID-pos patients more frequently had a history of diabetes (P = .016) and alcoholism (P = .023), a lower leukocyte count (P = .014) and a higher mortality rate - 29.2% versus 14.4% - (P = .014) when compared to COVID-neg patients. Patients on PPIs were 2.3 times less likely (odds ratio [OR] = 0.4381, 95% confidence interval [CI] [0.2331, 0.8175], P = .0053) to develop COVID-19 infection, compared to those not on PPIs. No other treatment decreased or increased this risk. COVID-pos patients on antipsychotics (P = .0013) and OADs (P = .0153), particularly metformin (P = .0237), were less likely to die. Thus, patients on treatment with PPI were less likely to develop COVID-19 infection, and those on antipsychotics or metformin had a lower risk of mortality. However, prospective studies, including clinical trials, are needed to confirm or not these findings.

Stacking Versatility in Alkali-Mixed Honeycomb Layered NaKNi2TeO6

The reaction between P2-type honeycomb layered oxides Na₂Ni₂TeO₆ and K₂Ni₂TeO₆ enables the formation of NaKNi₂TeO₆. The compound is characterized by X-ray diffraction and ²³Na solid-state nuclear magnetic resonance spectroscopy, and the structure is discussed through density functional theory calculations. In addition to the honeycomb Ni/Te cationic ordering, NaKNi₂TeO₆ exhibits a unique example of alternation of sodium and potassium layers instead of a random alkali-mixed occupancy. Stacking fault simulations underline the impact of the successive position of the Ni/Te honeycomb layers and validate the presence of multiple stacking sequences within the powder material, in proportions that evolve with the synthesis conditions. In a broader context, this work contributes to a better understanding of the alkali-mixed layered compounds.

Controlled Nanostructuration of Cobalt Oxyhydroxide Electrode Material for Hybrid Supercapacitors

Nanostructuration is one of the most promising strategies to develop performant electrode materials for energy storage devices, such as hybrid supercapacitors. In this work, we studied the influence of precipitation medium and the use of a series of 1-alkyl-3-methylimidazolium bromide ionic liquids for the nanostructuration of β(III) cobalt oxyhydroxides. Then, the effect of the nanostructuration and the impact of the different ionic liquids used during synthesis were investigated in terms of energy storage performances. First, we demonstrated that forward precipitation, in a cobalt-rich medium, leads to smaller particles with higher specific surface areas (SSA) and an enhanced mesoporosity. Introduction of ionic liquids (ILs) in the precipitation medium further strongly increased the specific surface area and the mesoporosity to achieve well-nanostructured materials with a very high SSA of 265 m2/g and porosity of 0.43 cm3/g. Additionally, we showed that ILs used as surfactant and template also functionalize the nanomaterial surface, leading to a beneficial synergy between the highly ionic conductive IL and the cobalt oxyhydroxide, which lowers the resistance charge transfer and improves the specific capacity. The nature of the ionic liquid had an important influence on the final electrochemical properties and the best performances were reached with the ionic liquid containing the longest alkyl chain.

Nanoparticles (NPs) of WO3-x Compounds by Polyol Route with Enhanced Photochromic Properties

Tungsten trioxide (WO₃) is well-known as one of the most promising chromogenic compounds. It has a drastic change of coloration induced from different external stimuli and so its applications are developed as gas sensors, electrochromic panels or photochromic sensors. This paper focuses on the photochromic properties of nanoWO₃, with tunable composition (with tunable oxygen sub-stoichiometry). Three reference samples with yellow, blue and black colors were prepared from polyol synthesis followed by post annealing under air, none post-annealing treatment, or a post-annealing under argon atmosphere. These three samples differ in terms of crystallographic structure (cubic system versus monoclinic system), oxygen vacancy concentration, electronic band diagram with occurrence of free or trapped electrons and their photochromic behavior. Constituting one main finding, it is shown that the photochromic behavior is highly dependent on the compound’s composition/color. Rapid and important change of coloration under UV (ultraviolet) irradiation was evidenced especially on the blue compound, i.e., the photochromic coloring efficiency of this compound in terms of contrast between bleached and colored phase, as the kinetic aspect is high. The photochromism is reversible in a few hours. This hence opens a new window for the use of tungsten oxide as smart photochromic compounds.

Structural transformations of the La2−xPrxNiO4+δ system probed by high-resolution synchrotron and neutron powder diffraction

Subtle structural distortions in the La_2−xPr_xNiO_4+δ system are investigated using high resolution X-ray powder diffraction and neutron powder diffraction, analyzed by combined Rietveld refinements.

Tailoring the Composition of Eu3+-Doped Y3NbO7 Niobate: Structural Features and Luminescent Properties Induced by Spark Plasma Sintering

The defective fluorite-related Y₃NbO₇ host lattice was doped with Eu³⁺ ions to understand the influence of spark plasma sintering (SPS) process on this host lattice. The intrinsic disorder due to the occurrence of oxygen vacancies results in amorphous-type responses of the luminescent cations, and the spectral distribution varies as a function of the niobium content. Two spectral fingerprints of europium emissions were clearly enhanced. The correlation between luminescence, X-ray diffraction, and electron diffraction characterizations shows the existence of local inhomogeneity. Indeed, the particular nonequilibrium sintering conditions allowed pointing out a lack of miscibility within the Y₃NbO₇ solid solution domain. Thus, the SPS pellet is a composite of two extreme compositions. This phase demixing is mainly induced by the pressure coupled with a current effect that makes possible ionic migration in this Y₃NbO₇ ionic conductive matrix.

Tuning the Mn valence state in new Ca(0.66)Mn(2-x)Al(x)O4 (x≤ 0.4) oxides: impact on magnetic and redox properties

New Ca(0.66)Mn(2-x)Al(x)O4 (x≤ 0.4) solid solutions crystallizing with the CaFe2O4-type structure (SG: Pnma) were synthesized for the first time by the glycine-nitrate process. The structures were determined on the basis of XRD Rietveld analysis and electron diffraction investigation. While the CaMn3O6 ('Ca(0.66)Mn2O4') oxide adopts a monoclinic unit cell, the Al substitution for Mn (x = 0.2, 0.4) leads to an orthorhombic cell with only two Mn atomic positions, with different valence states, and 33% of Ca sites empty. The Ca molar concentration decreases down to 0.6 in order to increase the Mn valence leading to a phase mixture, whereas a slight Ca content increase up to 0.7 leads to a decrease of Mn valence in the pure phase. The Al(3+) ions are located at a specific Mn site because their ionic radii are close to that of Mn(4+) and a more isotropic environment. The unit cell parameters and volume strongly decrease for a low Al content and tend to an asymptotic value of x = 0.33-0.4, around the limit of solubility. As the Al content increases, the Mn valence state in the same slightly distorted octahedral site increases up to 4+ whereas the other octahedral site is highly elongated and corresponds mainly to Jahn-Teller Mn(3+). At x = 0.33, these two Mn sites correspond to Mn(4+) and Mn(3+) respectively. Moreover, the aluminium content increase induces a weakening of the global antiferromagnetic long range interactions between the ferromagnetic chains. The Al substitution leads to the change of the Mn valence distribution as well as the unit cell symmetry of the CaMn3O6 phase. These 1D tunnel networks stabilizing the Mn(3+)/Mn(4+) valence states can be reduced under Ar/5%H2 between T = 300 °C and T = 600 °C (heating rate = 2 °C min(-1)) into pure Mn(2+) rocksalt solid solution despite the large difference in ionic radii. The re-oxidation leads to the same CaFe2O4-type structure and several redox cycles can be operated. The relationship between the two double chains of the edge-sharing octahedral sites and the rocksalt-type framework is clear and should appear as the driving force for the structural transformation during the reduction/oxidation processes. Finally, Al substitution allows an increasing of the Mn-O bond covalence and consequently the reduction in temperature.

Growth of high quality single crystals of strontium doped (Nd,Pr)-nickelates, Nd2−xSrxNiO4+δand Pr2−xSrxNiO4+δ

High quality, large size single crystals of Nd_2−xSr_xNiO_4+δand Pr_2−xSr_xNiO_4+δ(x= 0.0, 0.1 and 0.5) were successfully grown using the TSFZ technique.

Different Cerium Valence Transitions Observed by Hydrogenation of the Ternary Germanides CeRhGe and CeIrGe – Structure, Physical Properties and Chemical Bonding

The ternary germanides CeRhGe and CeIrGe which crystallize in the orthorhombic TiNiSi-type structure, absorb hydrogen at 523 K. X-Ray powder diffraction and transmission electron microscopy indicate that the hydrides CeRhGeH1.8 and CeIrGeH1.8 adopt the hexagonal ZrBeSi-type structure. Magnetization, electrical resistivity and thermoelectric power measurements reveal that these hydrides are intermediate-valence compounds. An unusual transition from antiferromagnetic to spin fluctuation behavior occurs upon hydrogenation of CeRhGe, while on the contrary, CeIrGeH1.8 presents a Kondo temperature of 285 K smaller than that observed for CeIrGe (610 K). In order to explain these opposite valence transitions, the electronic structures of the hydrides have been selfconsistently calculated within the local spin density functional theory (LSDF). The structures are compared to those reported previously by us for CeRhGe and CeIrGe.

Structural, Magnetic and Electrical Properties of the Ternary Silicide Gd6Co1.67Si3 Derived from the Hexagonal Ho4Co3.07 (or Ho6Co4.61) Type Structure

The title compound was discovered as an impurity phase in many GdCoSi samples. It crystallizes in the hexagonal space group P63/m with a = 11.7787(5) and c = 4.1640(2) Å . Using X-ray powder diffraction, an ordered distribution between Co and Si was found but one site is not fully occupied by Co for steric reasons. Magnetization measurements reveal that Gd6Co1.67Si3 exhibits a ferromagnetic transition at TC = 294(2) K, a Curie temperature similar to that reported for pure gadolinium. This magnetic ordering has been confirmed by electrical resistivity investigations.

Thermal stability of Li2MnO3: from localized defects to the spinel phase

The thermal stability of Li(2)MnO(3) has been investigated by the means of coupled differential thermal analysis and thermogravimetric analysis associated with powder X ray diffraction. Various experiments performed in air and in argon allowed us to propose a mechanism of spinel-type defects formation in intergrowth with Li(2)MnO(3) when treated in air above 900 °C. The fidelity of the DIFFaX simulations performed led to the understanding of the influence of the existence of spinel type defects intergrowth on X ray and electron diffraction patterns. The formation of these defects occurs during cooling and is preceded by the formation of LiMnO(2) defects in heating. With sufficiently long thermal treatments, defects expand such that a spinel type phase can be observed after cooling.

On the strongly correlated electron hydride Ce2Ni2MgH7.7

The intermediate valence compound Ce 2Ni 2Mg absorbs irreversibly hydrogen when exposed under 1 MPa of H 2 pressure at room temperature. The resulting hydride Ce 2Ni 2MgH 7.7 is stable in air and crystallizes as the deuteride La 2Ni 2MgD 8 in a monoclinic structure (space group P2 1 /c) with the unit cell parameters a = 11.7620(2), b = 7.7687(2), and c = 11.8969(2) A and beta = 92.75 degrees . The H-insertion in Ce 2Ni 2Mg induces a structural transition from a tetragonal to a monoclinic symmetry with an unit cell volume expansion Delta V m/ V m approximately 24.9%. The investigation of the hydride by magnetization, electrical resistivity, and specific heat measurements indicates a change from an intermediate valence behavior to a non-magnetic strongly correlated electron system. This transition results from a change of the coupling constant J cf between 4f(Ce) and conduction electrons induced by the hydrogenation.

Lithium deintercalation in LiFePO4 nanoparticles via a domino-cascade model

Lithium iron phosphate is one of the most promising positive-electrode materials for the next generation of lithium-ion batteries that will be used in electric and plug-in hybrid vehicles. Lithium deintercalation (intercalation) proceeds through a two-phase reaction between compositions very close to LiFePO(4) and FePO(4). As both endmember phases are very poor ionic and electronic conductors, it is difficult to understand the intercalation mechanism at the microscopic scale. Here, we report a characterization of electrochemically deintercalated nanomaterials by X-ray diffraction and electron microscopy that shows the coexistence of fully intercalated and fully deintercalated individual particles. This result indicates that the growth reaction is considerably faster than its nucleation. The reaction mechanism is described by a 'domino-cascade model' and is explained by the existence of structural constraints occurring just at the reaction interface: the minimization of the elastic energy enhances the deintercalation (intercalation) process that occurs as a wave moving through the entire crystal. This model opens new perspectives in the search for new electrode materials even with poor ionic and electronic conductivities.

Superstructures in Room-temperature Ordered Deuterides CeCuSiDx and CeCuGeDx

Crystallographic superstructures in the deuterides CeCuSiD1.64(5) and CeCuGeH1.15(5) have been characterized by neutron diffraction. Deuterium atoms are inserted in [Ce3Cu] and [Ce3Si] or [Ce3Ge] tetrahedral sites available in the hexagonal ZrBeSi-related structure of these deuterides. A partial but ordered occupancy of these tetrahedra by D atoms induces the occurrence of superstructures along the c axis, and the CeCuXDy structures can be described with a c parameter multiplied by 3 and 7 for X = Ge and Si, respectively, in comparison with the c parameters of the ZrBeSi-type subcells.

Microcystic Adnexal Carcinoma: Report of Seven Cases Including One with Lung Metastasis

BACKGROUND

Microcystic adnexal carcinoma (MAC) is a rare cutaneous neoplasm, with a high rate of local recurrences.

OBJECTIVE

A series of MAC was analyzed and compared to previously published cases.

METHODS

Seven cases of MAC were identified in the register of the institution. Medical and pathological records were reviewed.

RESULTS

The primary MAC were located on the face in all patients, and 85% were initially misdiagnosed. The mean follow-up duration was 108 months. The recurrence rate was high: 4 patients developed recurrences. In 3 patients, the course of the disease was severe: one of them developed pathologically proven lung metastasis.

CONCLUSION

The present study and review of the literature confirm the clinically aggressive evolution of MAC and its rare ability to give rise to metastasis. Long-term clinical follow-ups with imaging investigations are mandatory.

Supercritical fluid technology of nanoparticle coating for new ceramic materials

This work highlights, for the first time, the coating of ferroelectric nanoparticles with a chemical fluid deposition process in supercritical fluids. BaTiO3 nanoparticles of about 50 nm are coated with a shell of a few nanometers of amorphous alumina and can be recovered as a dry powder for processing. The sintering of these core-shell nanoparticles gives access to a ceramic material with very interesting ferroelectric properties, in particular, dielectric losses below 1%.

Study of disorder in a tetragonal tungsten bronze ferroelectric relaxor: a structural approach

Electron diffraction analysis, nuclear magnetic resonance measurements, structure determinations and refinements were performed on two ferroelectric lead-containing ceramics (classical and relaxor), with tetragonal tungsten bronze structure, in order to investigate the origin of the relaxor behaviour in such compounds. In both compounds the lead atoms are found to be off-centred in the CN (coordination number) 15 (A2) site. The main difference between the two compositions is the proportion of lead in this site: in the relaxor composition, theA2 site is at least half occupied by lead atoms. Disorder in the repartition of lead and potassium atoms in theA1 (CN 12) andA2 sites was also studiedviacombinatorial calculations to correlate the evolution of the relaxor behaviour in the Pb5Ta10O30–Li10Ta10O30–K10Ta10O30ternary system with composition. The combinatorial study demonstrated that the relaxor behaviour is enhanced by the disorder in cationic repartition.

[Pigmented nodular tenosynovitis. A misdiagnosed etiology of isolated tumefaction of fingers or toes]

BACKGROUND

Pigmented nodular tenosynovitis (more commonly called giant cell tumor) is a benign tumor of synovial joint or tendon sheaths.

CASE REPORT

A 17-year-old girl had a tumefaction of the first toe. The mass was firm and painless and had been present for one year. Radiological studies revealed a cystic area of the first phalanx. Magnetic resonance imaging demonstrated a poorly vascularized tissular lesion. Surgical excision of the tumor was performed. Macroscopic and histologic findings confirmed the diagnosis of pigmented nodular tenosynovitis.

DISCUSSION

Clinical and radiological aspects of nodular tenosynovitis are characteristic. This diagnosis should be made by dermatologists. Eighty percent of cases occur in fingers and more rarely in toes. Patients are usually females (60 p. 100). A subcutaneous mass is the most common presenting sign whereas pain or joint swelling are rare. Optimal treatment is surgical resection. The only risk is recurrence (20 p. 100).

CD101 is expressed by skin dendritic cells. Role in T-lymphocyte activation

CD101 was first described in our laboratory using two different monoclonal antibodies, BA27 and BB27, recognizing a 140-kDa disulfide-bonded homodimeric polypeptide on a small subset of circulating T lymphocytes and on most activated T cells in vitro. Further, it has been reported that most intestinal mucosal T lymphocytes expressed CD101. The gene coding for the CD101 antigen has been cloned and found to be identical to the gene coding for the recently described V7 antigen, corresponding to a type I trans-membrane protein with seven immunoglobulin-like loops in its extracellular domain. To define surface proteins that are involved in skin dendritic cell (DC) localization or function, we looked for the expression of CD1O1 on skin DC migrating from human skin explants. The majority of these DC had a phenotype of Langerhans cell (LC)-like mature DC, i.e., HLA-DR+ CD1a+ CD1c+ CD11a+ CD11c+ CD40+ CD50+ CD54+ CD58+ CD80+ CD83+ CD86+. We found that CD101 was expressed by a major subset of these HLA-DR+ CD1a+ CD1c+ LC-like skin DC. Next, we studied the effect of anti-CD101 monoclonal antibodies on primary allogeneic and on soluble antigen-specific mixed skin DC-lymphocyte reactions. We showed that two different monoclonal antibodies, BB27 and V7.1, inhibited the T-lymphocyte proliferative responses and that the inhibitory effect was overcome by high doses of exogenous IL-2. As both DC and T lymphocytes expressed CD101 molecules, we determined that the inhibitory effect was achieved both at the responder T-cell level and at the DC level. Thus, CD101 which is expressed on a subset of circulating T lymphocytes, has also been found on a subpopulation of LC-like DC. This molecule plays a major role in the activation of T cells by skin DC.

Application of PCR site-directed mutagenesis for a rapid and accurate detection of mutation 3500 (Arg-->Gln) of human apolipoprotein B-100

A rapid detection of the Arg3500-->Gln mutation of human apolipoprotein B-100 is of particular interest because of its prevalence in familial forms of hypercholesterolemia. A simple procedure, based on amplification by polymerase chain reaction (PCR) and NlaIII endonuclease restriction cleavage, allows this diagnosis without ambiguity. By using two oligonucleotide primers carrying one mismatch each, two permanent restriction sites were generated in the normal allele, while one of them disappeared in the mutant allele. Thus, the two alleles can be differentiated by their specific N/aIII restriction profile.