A novel optically transparent RF shielding for fully integrated PET/MRI systems.

Preclinical imaging benefits from simultaneous acquisition of high-resolution anatomical and molecular data. Additionally, PET/MRI systems can provide functional PET and functional MRI data. To optimize PET sensitivity, we propose a system design that fully integrates the MRI coil into the PET system. This allows positioning the scintillators near the object but requires an optimized design of the MRI coil and PET detector. It further requires a new approach in realizing the radiofrequency (RF) shielding. Thus, we propose the use of an optically transparent RF shielding material between the PET scintillator and the light sensor, suppressing the interference between both systems. We evaluated two conductive foils (ITO, 9900) and a wire mesh. The PET performance was tested on a dual-layer scintillator consisting of 12 × 12 LSO matrices, shifted by half a pitch. The pixel size was 0.9 × 0.9 mm2; the lengths were 10.0 mm and 5.0 mm, respectively. For a light sensor, we used a 4 × 4 SiPM array. The RF attenuation was measured from 320 kHz to 420 MHz using two pick-up coils. MRI-compatibility and shielding effect of the materials were evaluated with an MRI system. The average FWHM energy resolution at 511 keV of all 144 crystals of the layer next to the SiPM was deteriorated from 15.73 ± 0.24% to 16.32 ± 0.13%, 16.60 ± 0.25%, and 19.16 ± 0.21% by the ITO foil, 9900 foil, mesh material, respectively. The average peak-to-valley ratio of the PET detector changed from 5.77 ± 0.29 to 4.50 ± 0.39, 4.78 ± 0.48, 3.62 ± 0.16, respectively. The ITO, 9900, mesh attenuated the scintillation light by 11.3 ± 1.6%, 11.0 ± 1.8%, 54.3 ± 0.4%, respectively. To attenuate the RF from 20 MHz to 200 MHz, mesh performed better than copper. The results show that an RF shielding material that is sufficiently transparent for scintillation light and is MRI compatible can be obtained. This result enables the development of a fully integrated PET detector and MRI coil assembly.

[Pre-examination phase: perimeter and process description]. / Périmètre et description de l'étape pré-analytique.

This document describes the perimeter and the content of the pre-examination phase using a process approach, i.e. a transversal and functional description of this activity. Pre-examination phase progresses trough steps differently combined according to the circumstances. Each step may be described as a sub-process characterized by an objective, intrinsic elements (beginning/end, input and output elements, upstream and downstream process, actors and technical means) and specific requirements. Ten steps have been defined from customer (patient and prescriber) information to transport. This process approach of pre-examination phase has several advantages: exhaustiveness, customer expectations listing at each step, risk to be prevented and anticipation of potential failures. We propose a tool allowing afterwards to optimize one or the other step and to secure it using procedures and monitoring based upon indicators.

[Guidelines relative to the collection and handling management of biological samples]. / Recommandations pour la maîtrise de l'étape de prélèvement des échantillons biologiques.

Guidelines relative to the management of samples collection and handling for common tests are proposed with a list of websites to improve knowledge concerning the practices of biological sampling. Then, methodology is given for the creation of an electronic primary sample collection manual for medical laboratory tests. A list containing the medical laboratory tests for which the information and/or particular documents are needed either for the request or interpretation is presented. Another list for some specific laboratory tests with special individual requirements is proposed. We give also items allowing a standardized description of laboratory tests to help to create a personalized list of the available examinations, facilitating the information of professionals.

[Guidelines for the pre-examination processing and transport of medical laboratory samples]. / Recommandations concernant le traitement pré-analytique et le transport des échantillons de biologie médicale.

We resume here the guidelines about sample processing and transport for laboratory tests. All the steps of the pre-examination phase process, downstream to the recording of the requests, are described in this document. The purpose is to assure a secure and optimal sample management. The traceability of all the steps of the process is needed for the sample treatment and preservation. Then, we propose guidelines for the transport management step, according to the regulations and conditions to be applied to guarantee the sample integrity.

[Guidelines concerning sample reception and request recording of laboratory tests]. / Recommandations concernant l'accueil et l'enregistrement des échantillons de biologie médicale.

The process is described to help to achieve the requirements of the ISO 15189 standard. The precautions to be respected for a correct recording of the request are specified. The criteria for traceability are formalized. A logogram illustrates the propositions of attitude to be followed when occurs nonconformities. Then, we propose guidelines for the treatment of the identification uncertainties of the primary sample. An algorithm is proposed to formalize the process and treat the situations which can be met with an irreplaceable or critical sample.

[Self assesment grid for pre-examination phase]. / Proposition de grille d'auto-évaluation de la phase pré-analytique.

This document is a proposal of questionnaire for self-assessment of pre-analytical phase referring to the different steps described in the document SG1-01. The questions are aimed at verifying that what is examined fulfills ISO 15189 standard requirements or in general tends towards client satisfaction. This questionnaire has been elaborated using 5 M risk assessment tool for exhaustiveness purpose. This document may be useful to develop internal audit grids.

Antitubulin antibodies. II. Natural autoantibodies and induced antibodies recognize different epitopes on the tubulin molecule.

Natural and induced antitubulin antibodies were compared for their epitope recognition on alpha- and beta-tubulin subunits by immunoenzymatic assays and Western blot techniques on partially digested tubulin molecules. Our results indicated that natural autoantibodies recognized different epitopes from those recognized by induced antibodies, because: 1) all polyspecific natural autoantibodies tested so far recognized the same or very overlapping epitopes in the central part of both alpha- and beta-subunits (between positions 100 and 300 on the tubulin amino acid sequence) and that this epitope differed from the various epitopes recognized by induced antitubulin antibodies on the amino-terminal or carboxy-terminal parts of the tubulin subunits; 2) one human myeloma protein (monoclonal (m)IgA, kappa) with a monospecific antitubulin activity bound to an epitope around position 310 on both alpha- and beta-subunits and a second human mIg (mIgM, kappa) with a monospecific anti-beta activity bound to an epitope on the carboxy-terminal part of the subunit around amino acid position 350. Both epitopes differed from epitopes recognized by induced antitubulin antibodies. These results thus confirmed our previous findings indicating that natural and induced antitubulin antibodies do not share cross-reactive idiotopes.

Distribution of Trop 3 and 4 antigens in human endometrial glandular epithelium.

The reactivities of three monoclonal antibodies (MAbs), Trop 3, Trop 4, and W6/32, were studied on human uterine tissue by using an indirect immunoperoxidase method. Nonpregnant endometrial glandular epithelium was stained by all three MAbs. During pregnancy, Trop 3 expression was not detectable, but Trop 4 and W6/32 showed variable staining on the endometrial glandular epithelium, especially during late pregnancy. These findings support previous work suggesting a local regulation of antigenic expression by endometrial glandular epithelial cells.

Human serum reacting specifically with a subset of beta-tubulin isoforms.

The serum of a patient suffering from myeloma was found to decorate microtubules and mitotic spindles of cultured cells. Immunoblots performed after one- and two-dimensional electrophoresis showed a reaction with a certain subset of beta-tubulin isoforms, but not with beta'- and alpha-tubulins. The tubulin subset contained both ubiquitous (beta-3) and neurospecific (beta-4,5,6) isoforms. An IgM lambda and an IgA kappa myeloma protein were found in this serum. Immunoblots performed with specific anti-isotype second antibodies showed that the tubulin subset could be evidenced using anti-mu, alpha, lambda, and kappa-specific antisera. Moreover, the tubulin subset was also evidenced using an anti-gamma second antibody. These results, which do not exclude a participation of the myeloma proteins in the anti-tubulin reactivity, indicate, however, that the antibody response was polyclonal. The same restricted specificity of all classes of anti-tubulin antibodies of this serum favours the hypothesis that the immune response of the patient was directed against an antigen sharing epitopes with tubulin rather than with tubulin itself.

IL2-like material is present in human placenta and amnion.

Human term placenta was shown to react with different polyclonal and monoclonal anti-interleukin 2 (IL2) antibodies by using indirect immunofluorescence on frozen sections. Labelling was localized on syncytiotrophoblast membrane, amniotic epithelium and cytotrophoblast of the reactivity [corrected]. The reproducibility of the observations with different basal plate. These features were observed with two different rabbit anti-IL2 polyclonal antibodies, a sheep IL2 antiserum and 15.2, an anti-IL2 monoclonal antibody. However, DMS-1, a second anti-IL2 monoclonal antibody, did not react. Pre-incubation of anti-IL2 sera with IL2 resulted in the disappearance of syncytiotrophoblast reactivity. The reproducibility of the observations with different reagents strongly suggests that the recognized molecule shares several epitopes with IL2. However, it has not been possible to demonstrate the presence of a conventional IL2 receptor by using two monoclonal antibodies directed to the 55 kDa chain of IL2 receptor.

Distribution of Trop 3 and 4 antigens as defined by monoclonal antibodies raised against a human choriocarcinoma cell line.

The reactivities of Trop 3 and 4 monoclonal antibodies (MAbs) were studied on human term and 7-week extraembryonic membranes, adult tissues, and cell lines. Trop 3 MAb reacted with cells of chorionic villi, decidua, amniotic epithelium, and basal plate trophoblast. Trop 4 MAb reacted only with syncytiotrophoblast. On epithelium, Trop 3 MAb bound to stratified and glandular epithelium, but Trop 4 MAb reactivity was limited to basal keratinocytes. On peripheral blood mononuclear cells, Trop 3 MAb reacted with the majority of cells and Trop 4 MAb with the totality. Most cell lines were positive with both MAbs. However, one chemically induced MHC mutant was negative and another decreased its expression of Trop 3 antigen. Our results suggest Trop 3 MAb might recognize a monomorphic determinant of TLX antigens and Trop 4 is involved in cell proliferation or in cell-to-cell interaction.

[Physiology of Langerhans cells and their potential role in oral pathology]. / Physiologie des cellules de Langerhans et rôle potentiel en pathologie orale.

Langerhans cells represent a minor epidermal cell population in mammals. They are also observed in squamous epithelia of the oesophagus, vagina and cervix, as well as in oral epithelia. They occur in higher density in the non keratinized epithelium. These cells are characterized by a dendritic pattern, a clear cytoplasm and ultrastructurally by the presence of Birbeck granules. They are usually located in a suprabasal position. Their bone marrow origin is now well established. Surface markers and functional properties identify them as belonging to the macrophage/monocyte lineage. Langerhans cells can be identified in tissue sections by immunofluorescence or immunoperoxidase techniques using monoclonal antibodies directed against surface antigens such as class II histocompatibility antigens, T6 marker, or possibly T4 marker. There is also a cytoplasmic marker, the S-100 protein. A renewed interest in Langerhans cells comes from evidence of their role in the cutaneous immune response. At present these cells are considered as dendritic cells expressing a high density of class II histocompatibility antigens and behave as very potent antigen presenting cells that activate mainly helper T lymphocytes. However, experimental data on antigen processing and interleukin 1 secretion are still lacking. This review also examines the oral pathology literature with respect to modifications in the number or localization of Langerhans cells and their proximity to T lymphocytes, for example in lichen planus, Behcet's syndrome, erythema multiforme, gingivitis and oral carcinoma. Histiocytosis X represents a particular case in which the Langerhans cell itself is affected.

HLA in families with Down's syndrome children.

Thirty couples having a DS child were typed for HLA-A and B antigens and compared to twenty control families and 176 blood donors. Although differences in frequency of B antigens exist between DS families and controls, they are not significant after correction for the number of antigens tested. No excessive HLA sharing was found in DS parents contrarily to two previous studies (Mattironi et al. 1981, Aymé et al. 1983).

[Modifications of the maternal immune response associated to pregnancy (author's transl)]. / Modifications de la réponse immune lors de la grossesse.

The author reviews the literature on the immune status of pregnant women. No major alteration of the immune response was observed. If any, the modifications are not important and involve the synthesis of immunoglobulins, the presence of circulating immune complexes, some sub-populations of mononuclear cells and the in vitro lymphocyte response to T dependent antigens. Phagocytosis, the number of B and T cells and mitogen lymphocyte response are normal. Studies on the immuno-suppressive effect of both pregnant women sera and serum substances (hormones, pregnancy associated or specific proteins, carcino-embryonic antigens) are reported. Discrepancies are observed between conclusions drawn by various authors: they relate to the efficiency of the measurement and to the observed effect. The contradictory results obtained with alpha-foetoprotein provide an illustration of the critical analysis of these studies. Finally, the in vivo immune status of pregnant women is reported as observed in cutaneous tests, transplantations and auto-immune diseases. The most relevant observations are: a defect of the expression of delayed hypersensitivity reaction, a facilitating effect of pregnancy in kidney transplantation similar to that obtained after transfusion and an inconstant and mild defect of graft immunity. Therefore, pregnancy produces a specific immune status about which tests presently available give few relevant results, similar to those obtained in some cancers.