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Biomedical subjects

M Humbert

Publications and source records attributed to M Humbert.

16 recordsLinked to original sources
PubMed1992

Activation of macrophages and cytotoxic cells during cytomegalovirus pneumonia complicating lung transplantations.

The functional status of immune cells within human transplanted lungs was analyzed during cytomegalovirus (CMV) pneumonia complicating lung and heart-lung transplantations. The expression of interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6) genes is a marker for the activation of macrophages as is that of serine esterase B (SE-B) gene for cytotoxic cells. The levels of expression of these genes by bronchoalveolar lavage (BAL) cells were determined by in situ hybridization. Eight cases of CMV pneumonia were included in this study. BAL cells from either rejection episodes (eight cases) or control transplanted patients experiencing neither infection nor allograft rejection (eight cases) were analyzed in parallel. In the control patients, virtually no cells expressed the IL-1 beta, the IL-6, or the SE-B genes. In contrast, these three genes were all expressed in samples from patients with CMV pneumonia. IL-1 beta gene-expressing cells were abundant in all infected patients (mean +/- SEM: 898 +/- 449 positive cells per 10(4) cells, p less than 0.001, compared with those in control patients). IL-6 gene-expressing cells were less numerous (92 +/- 74 positive cells per 10(4) cells) and present in five of the eight cases of CMV pneumonia. Activated cytotoxic cells were detected in seven of the eight cases of CMV pneumonia (36.5 +/- 19 SE-B gene-expressing cells per 10(4) cells, p less than 0.001). During allograft rejections (eight cases) IL-1 beta gene-expressing cells were present in all but one patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Mouse B lymphocyte specific endocytosis and recycling of MHC class II molecules.

In B lymphocytes, the processing of exogenous proteins and the subsequent binding of antigenic peptides to class II molecules encoded by the major histocompatibility complex (MHC) occurs most likely within endocytic compartments. To examine the endocytic transport of MHC class II molecules, we used (i) surface iodination followed by internalization, pronase treatment and immunoprecipitation, (ii) in situ iodination of endosomal compartments, and (iii) confocal microscopy to visualize the fate of fluorescence coupled Fab fragments. In murine I-Ak, I-Ek positive B lymphoma cells, cell surface MHC class II molecules are partially protected from pronase digestion after 15 min at 37 degrees C and recycled back to the cell surface within the next 30 min. The fluorescence coupled Fab fragments are delivered to juxtanuclear endocytic compartments in 15 min. In contrast to the murine B cells, L fibroblasts transfected with either I-A alpha beta k or I-E alpha k beta k,d fail to internalize their surface class II molecules. A fraction of class II molecules, however, is still present in endosomal compartments as detected after in situ iodination in L fibroblasts. We conclude that the recipient L fibroblasts lack one or several factors needed for the transport of MHC class II molecules from the cell surface to the endosomes. We suggest that in murine B lymphoma cells, antigenic peptides can gain access to a pool of recycling class II molecules whereas in L cells they meet newly synthesized class II molecules targeted to the endosomal compartments.

Animals↗
PubMed1990

[B-lymphocyte hyperreactivity and differentiation factors of T-lymphocytes in systemic lupus erythematosus].

Polyclonal B cell activation is the most visible biological manifestation of systemic lupus erythematosus (SLE) autoimmunity. Murine models and in vitro lymphocyte studies are the most important tools used to improve our comprehension of the disease. It was successively demonstrated that there is an intrinsic B lymphocyte hyperreactivity in human and murine lupus; that the B lymphocytes overreact to stimulating factors produced by T lymphocytes; and that these stimulating factors could be over-produced. This last feature contrasts with decreased interleukin 2 production and lymphocyte response to this cytokine. A more precise study of the interleukins involved in the control of the humoral response shows the importance of interleukins 4, 5, 6 and of gamma-interferon. Further investigations are needed to improve our understanding of B cell hyperreactivity during SLE. These studies will benefit from better molecular characterization of many interleukins and their receptors.

Animals↗
PubMed1989

Use of glucose-6-phosphate dehydrogenase as a new label for nucleic acid hybridization reactions.

We describe here a sensitive new procedure for detecting DNA hybridization by dot blots. The method utilizes DNA or oligonucleotide probes labeled with biotin, sulfone, or haptens that can be detected by glucose-6-phosphate dehydrogenase (G6PDH) conjugates. Biotin labeling of DNA gave the best sensitivity. G6PDH activity was revealed by staining or by bioluminescence using an FMN oxidoreductase and a luciferase from Beneckea harveyi. Bioluminescent detection offered better sensitivity and faster revelation than the colorimetric assay and was found to be very useful in visualizing single mutations in human DNA after hybridization with an allele-specific biotinylated oligonucleotide probe. Revelation can be performed using a luminometer, photographic films, or a very sensitive video camera. The detection is limited by the nonspecific binding of the labeled reagent (streptavidin or antibodies). This limit is similar to that obtained with other nonisotopic labeling procedures, but our method is faster and several hybridization reactions can be performed on the same support.

Bacteriophage lambda↗
PubMed1989

A method of HLA class II typing using nonradioactive labelled oligonucleotides.

The typing of HLA class II genes using molecular biology techniques has brought undoubtedly new insights in the analysis of their polymorphism. Particularly interesting is the dot-blot analysis of enzymatically-amplified genomic DNA hybridized with sequence-specific oligonucleotides. In order to use this technique of typing on a routine basis, we established a non-radioactive detection method of enzymatically-amplified genomic DNA dot-blots. We could clearly demonstrate that, using biotin-labelled specific oligonucleotides, it was possible to specifically discriminate between DQB1 first domain DNA sequences displaying three, two or even only one base-pair difference at a given codon position. The very satisfactory sensitivity level reached by this non-radioactive detection method could safely allow its use for clinical applications of HLA typing at the DNA level.

DNA↗
PubMed1989

[Diagnosis of glucagonoma. Value of scanning, echography and arteriography. Apropos of 2 cases and a review of the literature].

The authors report two cases of glucagonoma, a rare endocrine tumor of the pancreas, and describe the data currently found in literature. Glucagonoma is a single and usually large tumor, which develops in the alpha cells of the islets of Langerhans and evolves slowly. The combination of characteristic skin lesions, diabetes and weight loss should lead to searching for hyperglucagonemia and for the pancreatic tumor. The diagnosis is usually made rather late, average evolution is five years before diagnosis when it is detected. Imaging, in particular ultrasound and computed tomography (CT), proves to be necessary for the positive diagnosis of glucagonoma as it localizes the pancreatic mass and plays a role in local assessment, thus providing guidance for surgery. The role of imaging is also fundamental for the detection of metastases, which are the only sign of malignancy as no criterion of benignity is found for this tumor.

Adenoma, Islet Cell↗
PubMed1989

[A new diagnostic approach in lymphangiomatosis. Apropos of a case].

Lymphangiomyomatosis is a rare disease affecting exclusively women usually in child-bearing age. It is characterized by proliferation of an atypical smooth muscle involving the pulmonary, mediastinal and retroperitoneal lymph system. The case reported here concerns a 53-year old woman presenting with an interstitial pulmonary lesion giving a characteristic image at CT. The patient also had recurrent chylothorax and a renal angiomyolipoma explored by CT and magnetic resonance imaging. The diagnosis of lymphangiomyomatosis was made on a cluster of arguments, without having recourse to surgical lung biopsy.

Chylothorax↗
PubMedDate not supplied

In vivo expression of IL-1 beta and IL-6 genes during viral infections in human.

Macrophage infiltration is a constant feature of human virus-infected tissues. However, the in situ functional status of these cells remains undetermined. In order to document an activation of macrophages in virus-infected tissues, the expression of IL-1 beta and IL-6 genes was analyzed using in situ hybridization. Several tissues were studied, as well as infections induced by different viruses: lymph nodes infected by HIV-1 (9 cases) or EBV (one case), lungs infected by CMV (5 cases) or adenovirus (1 case), livers infected by HBV, either chronically (2 cases) or acutely (7 cases presenting a fulminant hepatitis). With the exception of fulminant HBV hepatitis, IL-1 beta and IL-6 genes were expressed in all cases. IL-1 beta and IL-6 genes were usually coordinately regulated, as cells containing IL-1 beta or IL-6 mRNA were present in identical amounts and displayed a similar distribution. Analysis of the location and the morphology of monokine gene-expressing cells indicated that both small macrophages and endothelial cells expressed IL-1 beta and IL-6 genes. However, neither tingible body macrophages present in lymph node follicles nor Kupffer cells expressed these genes at a detectable level. Infected cells themselves were also negative for monokine gene expression. These findings indicate that expression of IL-1 beta and IL-6 genes by reactive cells may play a role in viral spreading limitation as well as virus-induced tissue damage.

AIDS-Related Complex↗