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M Bléry

Publications and source records attributed to M Bléry.

At least 19 recordsLinked to original sources
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↗
PubMed1996

Human and mouse killer-cell inhibitory receptors recruit PTP1C and PTP1D protein tyrosine phosphatases.

NK cells express cell surface receptors for MHC class I proteins (KIR). Engagement of these receptors inhibits NK cell cytotoxic programs. KIR can be expressed on T cells, and their engagement also results in inhibition of effector functions initiated by the CD3/TCR complex. While human KIR genes belong to the Ig gene superfamily, mouse KIR belong to a family of dimeric lectins. Despite these distinct evolutionary origins, we show here that both HLA-Cw3-specific human p58.183 receptors and H-2D d/k-specific mouse Ly49A receptors recruit the same protein tyrosine phosphatases, PTP1C and PTP1D, upon phosphorylation of critical intracytoplasmic tyrosine residues. These results document a common pathway by which diverse KIR can down-regulate NK and T cell activation programs, and further define the sequence of the immunoreceptor tyrosine-based inhibitory motif (ITIM), initially described in FcgammaRIIB1, and expressed in both human and mouse KIR.

Amino Acid Sequence↗
PubMed1996

Function of killer cell inhibitory receptors for MHC class I molecules.

NK- and T-cells express at their surface, members of a multigenic family of killer-cell inhibitory receptors (KIR) for MHC Class I molecules. KIR engagement leads to the inhibition of NK- and T-cell activation programs. These receptors recruit the protein tyrosine phosphatases (PTPase), SHP-1 and SHP-2, upon tyrosine phosphorylation of immunoreceptor tyrosine-based inhibition motif (ITIM) expressed in both human and mouse KIR. We further define the ITIM amino acids sequence required in that recognition and demonstrate the critical role of the phosphoY-2 amino acid residue in this V/IxYxxL/V motif. In addition, using RBL-2H3 cells expressing endogenous Fc epsilonRI receptors as well as transfected CD25/CD3zeta chimera and p58.183 human KIR, we show that KIR inhibitory function requires co-engagement of KIR and ITAM-containing receptors. These results document the pathway used by KIR to down-regulate NK- and T-cell activation programs.

Amino Acid Sequence↗
PubMed1996

Polyhedral microcalcifications on mammograms: prevalence and morphometric analysis.

OBJECTIVE: The purpose of this study was to determine the incidence and the mammographic appearance of polyhedral microcalcifications. MATERIALS AND METHODS: Prospectively, we evaluated screening mammograms in 2000 women for polyhedral microcalcifications. The number of polyhedral microcalcifications on routine and magnification views was established, and a quantitative analysis was done to determine if the shape of the polyhedral microcalcifications varied in the different projections. The ratio between the longer axis (R) and the shorter axis (r) was calculated. RESULTS: Two radiologists detected at least two polyhedral microcalcifications on one projection in 58 (3%) women. The number of polyhedral microcalcifications detected ranged from 2 to 47 (mean, 8.2) for screening mammograms and from 2 to 62 (mean, 13.4) on magnification views. Polyhedral microcalcifications were bilateral in 22 cases, scattered in one breast in 19 cases, segmental in 10 cases, and grouped in a cluster in seven cases. Lateral projections showed more rhombohedral microcalcifications, and craniocaudal projections showed more square microcalcifications. CONCLUSION: The frequency of polyhedral microcalcifications is 3%. The shape of polyhedral microcalcifications varies: craniocaudal views show them to be square and lateral views show them to be rhombohedral.

Breast↗
PubMed1995

Cholangiographic features in fibrosis and cirrhosis of the liver. Radiological-pathological correlation.

The cholangiographic features of intrahepatic bile ducts associated with cirrhosis or fibrosis are not well known. In order to achieve a radiological-pathological correlation, we studied nine livers with fibrosis or cirrhosis excised at autopsy. Cholangiograms were obtained within 24 hr after death from the nonfixed liver and multiple tissues samples were taken for histologic examination. Radiological data were interpreted by two independent investigators blinded to the clinical and histological findings. Cirrhosis (alcoholic in 4, posthepatitis in two) was observed in six livers, fibrosis (alcoholic in 2, posthepatitis in one) in three. No liver with fibrosis had cholangiographic abnormalities. In contrast, cholangiography of all livers with cirrhosis was abnormal. Abnormalities were a diminished arborization, a decrease of the distal opacification, an irregularity of caliber, and a tortuous course of the bile ducts. Histological study showed that the irregular and tortuous course were due to compression of the bile ducts by regenerative nodules. Furthermore, a thick fibrosis was organized around the bile ducts. In conclusion, fibrosis alone was not associated with cholangiographic abnormalities. In cirrhotic livers, intrahepatic bile ducts showed an irregular and tortuous course, a diminished arborization and a decrease of the distal opacification. These abnormalities were secondary to the presence of regenerative nodules and fibrosis organized around the bile ducts.

Autopsy↗
PubMed1995

Mammographic lesions suggestive of radial scars: microscopic findings in 40 cases.

PURPOSE: To analyze the histologic appearance of mammographically detected lesions suspected of being radial scars. MATERIALS AND METHODS: Mammographic and pathologic findings in 40 patients with a preoperative diagnosis of radial scar were reviewed retrospectively. RESULTS: Pathologic examination revealed 20 pure radial scars, 12 pure carcinomas, and eight malignant lesions (seven tubular carcinomas and one infiltrating ductal carcinoma) associated with a radial scar. At mammography, no difference was noted between benign and malignant lesions according to size and shape of the spicule, size of the central core, and the presence of calcifications. CONCLUSION: Because of the association of radial scars with borderline and malignant lesions, a spiculated lesion suggestive of a radial scar found at mammography must always be surgically removed. The surgeon and pathologist must be aware of the mammographic aspects of radial scar, however, to avert excessive surgery, because all cancers in this study had a good prognosis.

Adult↗
PubMed1995

[Tuberculous tenosynovitis of the wrist: ultrasonographic diagnosis and contribution of MRI].

Chronic tenosynovitis of the hand due to Mycobacterium tuberculosis has become rare. In the two cases presented here, the final diagnosis was obtained by isolation of the organism in the intercarpal fluid (1 case), or by a synovial biopsy (1 case). Ultrasonography showed a hypoechoic thickening of one or several tendon sheaths. MR enabled better differentiation between the thickening of the synovium itself and a fluid effusion. The criteria permitting to differentiate tuberculous from non-infectious tenosynovitis are: young age, male sex, specific epidemiological factors, elevated erythrocyte sedimentation rate, marked local swelling, association with other foci of tuberculosis, unusual exudation and synovial thickening, and association with osteitis.

Adult↗
PubMed1994

Correlation between contrast enhancement in dynamic magnetic resonance imaging of the breast and tumor angiogenesis.

RATIONALE AND OBJECTIVE: The authors determined the relation between tumor angiogenesis in small invasive breast carcinoma and contrast enhancement on magnetic resonance imaging (MRI) after gadolinium injection. MATERIALS AND METHODS: Magnetic resonance imaging was performed before surgery in a prospective study of 20 patients who had a small palpable lump. Spin-echo sequences after injection of gadolinium were studied by factor analysis of medical image sequences and were compared with a histologic quantification of tumor angiogenesis after immunocytochemical staining. RESULTS: In nine cases, there was good correlation between the MRI and the histologic plane. In four patients, an early factor was found on MRI. This factor was related to a high concentration of arterioles located in the stroma or, in one patient, to the intratumor repair process. CONCLUSION: Early enhancement correlated well with the number of vessels determined histologically.

Adult↗
PubMed1993

Polyhedral microcalcifications at mammography: histologic correlation with calcium oxalate.

Pathologists have associated calcium oxalate dihydrate (weddellite) in breast biopsy specimens with benign or borderline lesions and rarely with malignancy. These microcalcifications may have a polyhedral shape in histologic specimens owing to their crystalline structure. A retrospective radiologic-histologic correlation study was performed on 300 clusters of microcalcifications to determine if microcalcifications with a polyhedral shape could be found at mammography. In 19 cases (6.3%), polyhedral microcalcifications (PMs) were detected by two radiologists. In 12 of these 19 cases, weddellite crystals were found in the histologic specimen under polarized light; in seven cases, no calcification was found. Although rare, PMs can be found at mammography by radiologists aware of their existence. They are due to weddellite crystals and in this series were associated with benign disease in 89% of cases. Prospective studies are required to determine the frequency of PMs on screening mammograms and to evaluate their negative predictive value.

Breast↗
PubMed1990

[Study of the efficacy and tolerance of Iopamiron 370 compared to Telebrix Hystero in hysterosalpingography].

Hysterosalpingography is used to study the state of the uterine cavity as well as to analyse the patency of the tubes and the state of the tubal mucosa. It is difficult to find a contrast medium that has both the ideal qualities, be well tolerated and able to show fine pictures that have good contrasts, while at the same time are sufficiently viscous to allow up examination. The contrasts products that are used to carry out hysterosalpingography are often classed as viscous (Telebrix Hystero) and fluid (Iopamiron). This prospective randomised study compares local tolerance and efficiency of the two products. Fifty patients had Iopamiron and 48 Telebrix Hystero in July 1988 and February 1989. There was a statistical difference between the two groups which was significantly in favour of Iopamiron on the following features: Pain as noted on a questionnaire with steps of five points each (p = 0.02), Pain as described by the patient immediately after the examination on a visual analogue scale with p less than 0.01. Overall appreciation of the two products according to their tolerance and the efficiency of the products, which is to say the clearness of the pictures obtained with a p = 0.05.

Consumer Behavior↗
PubMed1989

[Rectal malacoplakia. Contribution of x-ray computed tomography and endorectal echography].

The authors report about the observation of a case of malacoplakia with rectal involvement. They lay stress on the usefulness of computed tomography and of rectal echography, which allow assessing extension within the rectal wall and, as the case may be, into the lymph nodes. These examinations also allowed following up the disease, the signs of which abated with antibiotic treatment.

Adolescent↗