STUDY BY MÖSSBAUER SPECTROSCOPY OF NEW SPINEL COMPOUNDS CONTAINING Fe3+ AND Sb5+ IONS

Nous avons étudié par spectroscopie Mössbauer du 57Fe, de nouveaux composés contenant des ions Fe3+ et Sb5+ et dérivant de la structure spinelle. Deux types de structures cristallographiques existent : cubique et orthorhombique, deux types de spectres Mössbauer y correspondent. Dans les composés cubiques, les ions Fe3+ occupent les sites B ; dans les orthorhombiques, ils occupent les sites A et B dans le rapport de population 2/1. Nous donnons aussi des informations magnétiques déduites des spectres Mössbauer.New compounds with Fe3+ and Sb5+ ions deriving from the spinel structure are studied by Mössbauer spectroscopy on 57Fe. Two kinds of crystallographic structures cubic and orthorhombic exist for these compounds and two kinds of Mössbauer spectra are observed. In the cubic compounds, Fe3+ ions occupy B sites ; in the orthorhombic one, they occupy A and B sites in the population ratio 2/1. Magnetic informations are also given from the Mössbauer spectra

Studies of spinels. (VIII) Synthesis and structural study of new antimonates M5II M3III SbO12 by X-ray diffraction and Mössbauer spectroscopy

X-ray and Mössbauer data on spinel antimonates, with formula (MII2MIII3) [MII8MIII2Sb2]O24, with MII = Mg, Zn, Ni and MIII = Fe, Ga are presented. The cationic orderings and distributions are widely discussed and even if no long-range cationic ordering appears, the Mössbauer data show a short-range one. Preliminary magnetic results are also obtained.Preudhomme J., Tarte P., Kenens R., Grandjean F., Gérard A. Studies of spinels. (VIII) Synthesis and structural study of new antimonates M5II M3III SbO12 by X-ray diffraction and Mössbauer spectroscopy. In: Bulletin de la Classe des sciences, tome 66, 1980. pp. 776-791

Large planar drift chambers

The authors describe 14 m/sup 2/ hexagonal planar drift chambers designed for the neutrino experiment of the CERN-Dortmund-Heidelberg- Saclay Collaboration. Details on mechanical construction, electronic read-out, results on efficiency and accuracy are presented. (6 refs)

The charged trigger system of NA48 at CERN

The NA48 charged trigger is a mixed hardware and software real time processing system intended to detect the interesting configurations of $K^{0}$ charged decays. It achieves real-time event building, track reconstruction and kinematics computation on drift chamber data at an event rate of 100 kHz and within a maximum decision latency of 100 $/mu$s. The system uses data driven, FPGA-based coordinate builders, a hardware event builder based on a crossbar switch, and a farm of up to 16 event processors for its software part. It has been installed and operated at CERN since 1995. After a description of the constraints and architecture of the various subsystems, the paper will give an account of the results and performance of the system based on the 1996/1997 runs. More specifically, the replacement of the present DSP-based implementation of the processing farm by RISC processors will be discussed

Anti-CD20 IgA can protect mice against lymphoma development: evaluation of the direct impact of IgA and cytotoxic effector recruitment on CD20 target cells.

International audienceBACKGROUND: While most antibody-based therapies use IgG because of their well-known biological properties, some functional limitations of these antibodies call for the development of derivatives with other therapeutic functions. Although less abundant than IgG in serum, IgA is the most abundantly produced Ig class in humans. Besides the specific targeting of its dimeric form to mucosal areas, IgA was shown to recruit polymorphonuclear neutrophils against certain targets more efficiently than does IgG1. DESIGN AND METHODS: In this study, we investigated the various pathways by which anti-tumor effects can be mediated by anti-CD20 IgA against lymphoma cells. RESULTS: We found that polymeric human IgA was significantly more effective than human IgG1 in mediating direct killing or growth inhibition of target cells in the absence of complement. We also demonstrated that this direct killing was able to indirectly induce the classical pathway of the complement cascade although to a lesser extent than direct recruitment of complement by IgG. Recruitment of the alternative complement pathway by specific IgA was also observed. In addition to activating complement for lysis of lymphoma cell lines or primary cells from patients with lymphoma, we showed that monomeric anti-CD20 IgA can effectively protect mice against tumor development in a passive immunization strategy and we demonstrated that this protective effect may be enhanced in mice expressing the human FcαRI receptor on their neutrophils. CONCLUSIONS: We show that anti-CD20 IgA antibodies have original therapeutic properties against lymphoma cells, with strong direct effects, ability to recruit neutrophils for cell cytotoxicity and even recruitment of complement, although largely through an indirect way

The gaseous microstrip detector Micromegas for the COMPASS experiment at CERN

The measurements foreseen in the COMPASS experiment at CERN, require high resolution tracking detectors, with low radiation length and high rate capability. For this purpose we have developed and optimized a gaseous microstrip detector 'Micromegas'. Twelve planes with 1024 strips each, assembled in 3 stations of 4 views XYUV, have been operated with success in the summer of 2002 in the COMPASS environment. We describe here the performances and results obtained. (3 refs)

Single-cell analysis reveals fibroblast clusters linked to immunotherapy resistance in cancer

International audienceA subset of Cancer-Associated Fibroblasts (FAP+/CAF-S1) mediates immunosuppression in breast cancers (BC), but its heterogeneity and its impact on immunotherapy response remain unknown. Here, we identify 8 CAF-S1 clusters by analyzing more than 19000 single CAF-S1 fibroblasts from BC. We validate the 5 most abundant clusters by flow cytometry and in silico analyses in other cancer types, highlighting their relevance. Myofibroblasts from clusters 0 and 3, characterized by extra-cellular matrix proteins and TGFB signaling respectively, are indicative of primary resistance to immunotherapies. Cluster 0/ecm-myCAF up-regulates PD-1 and CTLA-4 protein levels in regulatory T lymphocytes (Tregs), which in turn increases CAF-S1 cluster 3/TGFB-myCAF cellular content. Thus, our study highlights a positive feedback loop between specific CAF-S1 clusters and Tregs and uncovers their role in immunotherapy resistance