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Biomedical subjects

M Bléry

Publications and source records attributed to M Bléry.

At least 19 recordsLinked to original sources
PubMed2001

[Evaluation of plain abdominal radiography prescriptions in a university hospital center].

OBJECTIVES: The aim of this study was to evaluate the prescription, impact and diagnostic utility of plain abdominal radiography in a University Hospital. METHODS: Plain abdominal radiography series performed over 15 consecutive days were evaluated for quality and agreement with the patient's clinical status. Agreement between the final diagnosis and the radiographic findings were also compared. Contribution of plain abdominal radiography to final diagnosis was assessed on the basis of the conclusions on the hospital discharge report or from those drawn from a telephone survey. The same relationship was also assessed in terms of clinician status (medical student, resident physician, senior physician). RESULTS: The series included 175 radiography series (11.6 per day). In 86% of the cases, the choice of views was adapted to the clinical context. In 14% it was not. The quality of the x-rays was found to be unsatisfactory in 17%, good in 63% and excellent in 20%. The radiography was considered to be contributive to the final diagnosis in 13% of the cases and non-contributive in 87%. Clinician status was not correlated with the degree of usefulness for final diagnosis. Finally, the prescription was in agreement with standard guidelines in 28% of the cases and not in agreement in 72%. CONCLUSION: Plain abdominal radiographs are neither sensitive nor specific, frequently misleading, and costly per specific and correct diagnosis. Better physician awareness is required to limit the number of unnecessary examinations.

Abdomen↗
PubMed2001

Inhibition of IgE-mediated mast cell activation by the paired Ig-like receptor PIR-B.

The potential of the paired Ig-like receptors of activating (PIR-A) and inhibitory (PIR-B) types for modifying an IgE antibody-mediated allergic response was evaluated in mouse bone marrow-derived mast cells. Although mast cells produced both PIR-A and PIR-B, PIR-B was found to be preferentially expressed on the cell surface, where it was constitutively tyrosine phosphorylated and associated with intracellular SHP-1 protein tyrosine phosphatase. PIR-B coligation with the IgE receptor (FcepsilonRI) inhibited IgE-mediated mast cell activation and release of serotonin. Surprisingly, the inhibitory activity of PIR-B was unimpaired in SHP-1-deficient mast cells. A third functional tyrosine-based inhibitory motif, one that fails to bind the SHP-1, SHP-2, and SHIP phosphatases, was identified in parallel studies of FcepsilonRI-bearing rat basophilic leukemia (RBL) cells transfected with constructs having mutations in the PIR-B cytoplasmic region. These results define the preferential expression of the PIR-B molecules on mast cells and an inhibitory potential that can be mediated via a SHP-1-independent pathway.

Animals↗
PubMed2000

Signaling pathways engaged by NK cell receptors: double concerto for activating receptors, inhibitory receptors and NK cells.

Despite the absence of antigen-specific receptors at their surface, NK cells can selectively eliminate virus-infected cells, tumor cells and allogenic cells. A dynamic and precisely coordinated balance between activating and inhibitory receptors governs NK cell activation programs. Multiple activating and inhibitory NK cell surface molecules have been described, a group of them acting as receptors for MHC class I molecules. In spite of their heterogeneity, activating NK cell receptors present remarkable structural and functional homologies with T cell- and B cell-antigen receptors. Inhibitory NK cell receptors operate at early stages of activating cascades by recruiting protein tyrosine phosphatases via intra- cytoplasmic motifs (ITIM), a strategy which is widely conserved in hematopoietic and non-hematopoietic cells.

Cytotoxicity, Immunologic↗
PubMed2000

Primary malignant lymphoma of the urinary bladder: report of three cases and review of the literature.

We report three cases of a primary malignant lymphoma of the urinary bladder. The radiological features revealed a sessile mass of the lateral wall for one case, a circumferential thickening in the second, and two separated masses of the bladder wall in the last case. Primary malignant lymphoma of the urinary bladder is extremely rare. From a review of the literature, the clinical and radiological findings are discussed. In this paper we report the first case of urinary bladder lymphoma presented on CTas multiple masses.

Aged↗
PubMed2000

Early signaling via inhibitory and activating NK receptors.

This review focuses on recent findings on the structural features of inhibitory NK cell receptors containing immunoreceptor tyrosine-based inhibition motif (ITIM) and of NK cell activating receptors, both in human and mouse. First, the study of the inhibitory killer cell immunoglobulin-like receptors (KIR) unveiled the presence of intracytoplasmic ITIM and their capacity to recruit protein tyrosine phosphatases such as SHP-1 in vivo. A brief summary of the known SHP-1 targets may help us to understand the inhibition mediated by the KIR. The characterization of ITIM thus allowed the definition of a large group of inhibitory cell surface receptors. The second part of the review describes the known NK cell activating receptors. Most of them require association with ITAM-containing polypeptides in order to mediate cell activation.

Amino Acid Motifs↗
PubMed2000

[Evaluation of radiological medical practice at a hospital during night duty].

PURPOSE: To evaluate the radiological activity during night duty, in a University Hospital. Materials and methods. During 100 days, the radiological activity has been evaluated from examinations requiring radiologist (including US and CT, special X-ray examinations). The urgent nature and the agreement between the suspected disease and the final diagnose have been compared with the level of the clinician (medical student, resident, senior). RESULTS: 981 radiological examinations were performed on an emergency basis. In 39%, the examination was urgent or very urgent and for 61%, little urgent or non-urgent. The level of the clinician was correlated with the degree of emergency evaluated by the radiologist and with the agreement between suspected disease and the final diagnose (p<0. 0001). CONCLUSION: During night duty, the medical activity in radiology is not justified only by emergency, but also by the continuous hospital activities. Better formation of the physician is required to limit the number of examinations.

Emergency Service, Hospital↗
PubMed2000

[Imaging of acute urinary infections in adults. Radiologic findings and strategy for imaging procedures].

Urinary infection is very common in women. Generally no imaging is needed. The role of imaging is mandatory in the following cases: renal infection, urinary obstructive syndrome, immuno-compromised patients. The results of imaging in pathology are described: pyelonephritis, renal and perinephric abscesses with or without phlegmon, perinephritis and emphysematous perinephritis. A strategy for imaging procedures is proposed.

Abscess↗
PubMed1999

Intraluminal duodenal diverticulum: radiological and endoscopic ultrasonography findings of an unusual cause of acute pancreatitis.

Intraluminal duodenal diverticulum is a rare congenital web of membrane which may be symptomatic when it becomes distended. This report describes a case revealed by presenting as an acute pancreatitis. The radiological findings are reported. The findings at CT, upper gastro-intestinal series, endoscopic ultrasound and endoscopic retrograde cholangiopancreatography are described and differential diagnostic features from choledochocele and duodenal duplication are discussed. By endoscopic ultrasonography, observation of a thin wall, without different layers such as choledochocele or duodenal duplication, may be useful for diagnosis.

Acute Disease↗
PubMed1999

[Emphysematous pyelonephritis: apropos of 4 cases].

PURPOSE: The propose of this study was to describe the imaging findings in four patients with emphysematous pyelonephritis and to perform a review of the literature. MATERIAL AND METHODS: Four cases of emphysematous pyelonephritis are presented. US and CT examinations were available for all patients. RESULTS: Gas within the kidney may be diagnosed by plain film or rarely by ultrasound, but its location and its extent are best evaluated by CT. A review of the literature shows that emphysematous pyelonephritis is a rare and life-threatening infection typically occurring in diabetic patients. CONCLUSION: CT is useful for diagnosing emphysematous pyelonephritis, especially when symptoms fail to resolve promptly with medical therapy.

Adult↗
PubMed1998

Gene structure, expression pattern, and biological activity of mouse killer cell activating receptor-associated protein (KARAP)/DAP-12.

Natural killer cell and T cell subsets express at their cell surface a repertoire of receptors for MHC class I molecules, the natural killer cell receptors (NKRs). NKRs are characterized by the existence of inhibitory and activating isoforms, which are encoded by highly homologous but separate genes present in the same locus. Inhibitory isoforms express an intracytoplasmic immunoreceptor tyrosine-based inhibition motif, whereas activating isoforms lack any immunoreceptor tyrosine-based inhibition motif but harbor a charged amino acid residue in their transmembrane domain. We previously characterized KARAP (killer cell activating receptor-associated protein), a novel disulfide-linked tyrosine-phosphorylated dimer that selectively associates with the activating NKR isoforms. We report here the identification of the mouse KARAP gene, its localization on chromosome 7 and its genomic organization in five exons. Point mutation and transfection studies revealed that KARAP is a novel signaling transmembrane subunit whose transduction function depends on the integrity of an intracytoplasmic immunoreceptor tyrosine-based activation motif. In contrast to previous members of the immunoreceptor tyrosine-based activation motif polypeptide family, KARAP is ubiquitously expressed on hematopoietic and nonhematopoietic cells, suggesting its association with a broad range of activating receptors in a variety of tissues.

Adaptor Proteins, Signal Transducing↗
PubMed1998

The paired Ig-like receptor PIR-B is an inhibitory receptor that recruits the protein-tyrosine phosphatase SHP-1.

An emerging family of cell surface inhibitory receptors is characterized by the presence of intracytoplasmic immunoreceptor tyrosine-based inhibition motifs (ITIM). These ITIM-bearing inhibitory receptors, which are typically paired with activating isoforms, associate with Src homology domain 2-containing phosphatases following ITIM tyrosine phosphorylation. Two categories of phosphatases are recruited by the ITIM-bearing receptors: the protein-tyrosine phosphatases, SHP-1 and SHP-2, and the polyphosphate inositol 5-phosphatase, SHIP. The dynamic equilibrium of B cell activation is partially controlled by two well known ITIM-bearing receptors, CD22 and FcgammaRIIB, a low affinity receptor for IgG. We describe here that a murine ITIM-bearing molecule, PIR-B, can also negatively regulate B cell activation. Tyrosine-phosphorylated ITIMs allow PIR-B to associate with SHP-1 but not with SHIP. Engagement of PIR-B thereby initiates a SHP-1-dependent inhibitory pathway that may play an important role in regulating B lymphocyte activation.

Amino Acid Sequence↗
PubMed1997

Reconstituted killer cell inhibitory receptors for major histocompatibility complex class I molecules control mast cell activation induced via immunoreceptor tyrosine-based activation motifs.

Natural killer and T cells express at their surface, members of a multigenic family of killer cell inhibitory receptors (KIR) for major histocompatibility complex Class I molecules. KIR engagement leads to the inhibition of natural killer and T cell activation programs. We investigated here the functional reconstitution of KIR in a non-lymphoid cell type. Using stable transfection in the RBL-2H3 mast cell line, we demonstrated that (i) KIR can inhibit signals induced by FcepsilonRIgamma or CD3zeta polypeptides that bear immunoreceptor tyrosine-based activation motifs; (ii) two distinct immunoreceptor tyrosine-based inhibition motifs-bearing receptors, i.e. KIR and FcgammaRIIB, use distinct inhibitory pathways since KIR engagement inhibits the intracellular Ca2+ release from endoplasmic reticulum stores, in contrast to FcgammaRIIB, which only inhibits extracellular Ca2+ entry; (iii) KIR require co-ligation with an immunoreceptor tyrosine-based activation motif-dependent receptor to mediate their inhibitory function. This latter finding is central to the mechanism by which KIR selectively inhibit only the activatory receptors in close vicinity. Taken together our observations also contribute to define and extend the family of immunoreceptor tyrosine-based inhibition motif-bearing receptors involved in the negative control of cell activation.

Animals↗
PubMed1997

Mammographic pattern due to residual Lipiodol after galactography.

The purpose of this pictorial essay is to describe the different mammographic aspects of residual Lipiodol ultra fluid (LUF) after galactography, and to define some specific patterns, because it may in some cases mimic microcalcifications and give diagnostic problems. The mammograms of 14 patients, aged 32-63 years, presenting LUF residues related to previous galactography, were analyzed retrospectively. In 12 cases the diagnosis was easy because the patients presented a typical pattern on mammography and came with their initial galactography. In 2 cases the diagnosis was more difficult because the patients did not remember the previous injection and the progressive resorption mimicked perfectly intraductal calcification. Benign duct ectasia with inflammatory reaction to foreign bodies were found in 3 cases in which surgery was performed. Lipiodol ultra fluid is no longer used for galactography, but it may persist in breast ducts or cysts for years and seems to still be used in some countries. There are in most cases specific signs enabling the diagnosis.

Adult↗
PubMed1997

Transduction of cytotoxic signals in natural killer cells: a general model of fine tuning between activatory and inhibitory pathways in lymphocytes.

NK-cells are large granular lymphocytes, which are capable of exerting two major types of effector function, cell cytotoxicity and lymphokine secretion. NK-cells can exert cell cytotoxicity in one of two ways. First, NK-cells are able to recognize and to induce the lysis of antibody-coated target cells during antibody-dependent cell cytotoxicity (ADCC). Second, during natural cytotoxicity NK-cells are also able to recognize and to induce the lysis of a variety of target cells, including primarily virus-infected cells as well as tumor cells. Recently, a novel mechanism has been elucidated which controls NK-cell-activation programs and which is based on the cell surface expression of killer-cell inhibitory receptors (KIR). We will review here the molecular dissection of this inhibitory signalling pathway which utilizes immunoreceptor tyrosine-based inhibition motifs (ITIM) expressed in KIR intracytoplasmic domain. We will also show that this strategy used by NK-cells to regulate their effector functions is a general decision mechanism which exists not only in T- and B-lymphocytes, but also in a variety of other hematopoietic cells.

Amino Acid Sequence↗