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Biomedical subjects

A Moreau

Publications and source records attributed to A Moreau.

At least 145 records · Page 8Linked to original sources
PubMed1993

Effects of digitonin on the intracellular content of rat hepatocytes: implications for its use in the study of intralobular heterogeneity.

Anterograde or retrograde perfusion of rat liver with digitonin selectively permeabilizes the periportal or the perivenous zone of the hepatic lobule. Digitonin perfusion is used to analyze the effluents released by permeabilized hepatocytes or, combined with collagenase perfusion, to obtain cell suspensions enriched in either periportal or perivenous hepatocytes. Despite the wide use of digitonin to study lobular heterogeneity, its affects on rat hepatocytes are not well documented. We therefore analyzed the effects of digitonin perfusion on the intracellular content of rat hepatocytes by combining electron microscopy, histoenzymology, immunohistochemistry, and in situ hybridization. At the concentration currently used for the study of lobular heterogeneity, digitonin perfusion induced a marked cytosolic clarification of permeabilized hepatocytes, while most organelles except mitochondria were well preserved. In the digitonin-altered zones, there was no histochemical detection of non-membrane-bound enzymes (lactate dehydrogenase, glutamate dehydrogenase), whereas membrane-bound enzymes (succinate dehydrogenase, beta-hydroxybutyrate dehydrogenase, NADPH dehydrogenase, glucose-6-phosphatase) were still detected. Immunohistochemistry and in situ hybridization revealed significant amounts of several plasma proteins (albumin, alpha 2-macroglobulin, alpha 1-inhibitor 3, alpha 1-acid glycoprotein) and their respective mRNAs in digitonin-permeabilized hepatocytes. The demonstration that digitonin-permeabilized hepatocytes retain many intracellular constituents shows that biochemical analysis of cellular effluents released from digitonin-permeabilized hepatocytes must be interpreted with caution and that the apparent characteristics of cell suspensions obtained by the digitonin-collagenase technique might be significantly altered by contamination with permeabilized hepatocytes from the opposite zone.

Animals↗
PubMed1993

[Extramedullary hematopoiesis. An unusual cause of Pagetic spinal cord compression].

An original case is reported: spinal cord compression due to extramedullary hematopoiesis of the epidural space, related to Paget's disease of bone, successfully treated by surgery. Extramedullary hematopoiesis, usually occurring in cases of hematological disease, can also complicate Paget's disease, probably by bone effraction mechanism. A review of literature has found 5 other cases of extramedullary hematopoiesis occurring in Paget's disease, without hematological disease. Medullar scintigraphy (Indium111, Technetium99 Sulfur colloid) can confirm the diagnosis after X-ray findings, without the need for biopsy. Awareness knowledge of this complication can sometimes avoid invasive investigation. Low dose radiotherapy is useful in the case of hematological disorders. In Paget's disease, there is a risk of sarcomatous degeneration. In our patient, surgery cured cord compression, but it relapsed because of extensive fibrosis, in complicating surgical hemorrhage.

Aged↗
PubMed1993

[Bacillary peliosis in AIDS. Anatomo-clinical study of 2 cases].

The authors report two cases of peliosis hepatis, occurring in patients with AIDS, who presented a persistent fever and an hepatomegaly. The liver biopsies showed areas of peliosis, where bacilli were observed by Warthin-Starry stain. In one case, techniques of molecular biology allowed the identification of Rochalimaea henselae, pathogen involved in bacillary angiomatosis. This rickettsia has been newly recognized in the United-States, where 17 cases of bacillary peliosis have been published in immunocompromised hosts and mainly in patients with AIDS. These observations illustrate the clinical and histological features of this new opportunistic infection, as it is described in the literature. The clinical signs include an unexplained fever, an hepatomegaly, and in 75% of the cases, a splenomegaly. The cutaneous lesions of bacillary angiomatosis are associated in 40% of the cases. An antibiotic treatment by erythromycin ensures a complete recovery.

AIDS-Related Opportunistic Infections↗
PubMed1992

Cloning and expression in Escherichia coli of a xylanase-encoding gene from the yeast Cryptococcus albidus.

In the yeast, Cryptococcus albidus, a comparison between the sequence of the xylanase (XLN)-encoding chromosomal gene (XLN) and the cDNA sequence reveals the presence of seven introns, ranging in length from 51 to 69 bp. One of their 5' splice site sequences is similar to the consensus sequence for yeast, while the other six resemble the consensus sequence for higher eukaryotes. Their 3' end splice site sequences are representative of the conserved sequence found in eukaryotes. Their putative branching point sequences are different from the well-known conserved sequence, 5'-TACTAAC, observed in yeast, but again resemble the mammalian one. The cDNA encoding XLN is expressed by Escherichia coli, under the control of the lacZ promoter. The gene product remains inside the cell and has a molecular size of 40 kDa, which matches the size of the nonglycosylated protein. When compared to the glycosylated enzyme, the nonglycosylated XLN from E. coli shows twofold less affinity for substrate and its Vmax is 100-fold lower. Moreover, the nonglycosylated XLN only acts on large xylan polymers and very slightly on xylohexaose.

Base Sequence↗
PubMed1992

Secretion of a Cryptococcus albidus xylanase in Saccharomyces cerevisiae.

The xylanase(XLN)-encoding gene(XLN) of Cryptococcus albidus and its cDNA were each inserted into the vector, pVT100, for expression in Saccharomyces cerevisiae. Expression was under the control of either their own promoter or the gene encoding alcohol dehydrogenase (ADH1) promoter. Yeast transformed with plasmids containing the cDNA of the structural XLN gene and the XLN promoter produced active extracellular XLN when grown with galactose as carbon source. However, with glucose as carbon source, XLN was repressed. Using the ADH1 promoter, which is stimulated by glucose, XLN was secreted into the culture medium. In both cases, the secreted 48-kDa enzyme corresponded to the native XLN produced by C. albidus. With the plasmid bearing the genomic XLN gene, there was transcription, but the seven introns interrupting XLN were not spliced out by S. cerevisiae and no enzyme was produced.

Alcohol Dehydrogenase↗
PubMed1992

Drug-induced prolonged cholestasis in adults: a histological semiquantitative study demonstrating progressive ductopenia.

Drug-induced acute hepatitis may be followed by prolonged cholestasis despite the withdrawal of the drug. Eight patients suffering from prolonged cholestasis caused by several drugs were investigated with sequential liver biopsies. At the early stage, lesions of acute cholangitis were observed in most patients; at the chronic phase, ductopenia, defined by the absence of interlobular bile ducts in at least 50% of small portal tracts, was demonstrated in all patients. Ductopenia might be the consequence of acute cholangitis; the degree of ductopenia and the chronicity of the disease might be directly related to the severity of the early acute damage of bile ducts. Consequently, in patients with severe cholestasis related to drugs, research of early morphological signs of acute cholangitis and then of ductopenia seems to be important.

Adult↗
PubMed1992

Primary Epstein-Barr virus infection with clonal T-cell lymphoproliferation.

A case of fatal Epstein-Barr virus infection in a previously healthy girl who was first found to have severe infectious mononucleosis with spontaneous recovery is reported. Because an abnormal immune response to the virus persisted, the disease relapsed, manifesting in cutaneous and pulmonary lesions associated with hemophagocytic syndrome responsible for death. Pathologic findings were characterized by polymorphous atypical lymphoid infiltrate, prominent necrosis, and histiocytic hyperplasia. Lymphoid cells displayed CD8 phenotype and clonal T-cell receptor gene rearrangement. Viral genome was detected in lesions by Southern blot and located in nuclei of lymphoid cells by in situ hybridization. Pathologic findings suggested fatal infectious mononucleosis; however, phenotype and genotype favored a malignant diagnosis. Clonality was demonstrated to have arisen during primary infection. Virologic examination indicated that Epstein-Barr virus was a causative agent. Such a process belongs to the recently recognized spectrum of Epstein-Barr virus-related T-cell lymphoproliferative disorders that might overlap fatal infectious mononucleosis in patients who are especially vulnerable to the virus.

Adolescent↗
PubMed1992

A novel shuttle vector for Streptomyces spp. and Escherichia coli as a tool in site-directed mutagenesis.

This paper describes the construction and utilization of a novel shuttle vector for Streptomyces spp. and Escherichia coli as a useful vector in site-directed mutagenesis. The shuttle vector pIAFS20 (6.7 kb) has the following features: a replicon for Streptomyces spp., isolated from plasmid pIJ702; the thiostrepton-resistance gene as a selective marker in Streptomyces; the ColE1 origin, allowing replication in E. coli; and the ampicillin-resistance gene as a selective marker in E. coli. Vector pIAFS20 also contains the phage f1 intergenic region, which permits production of single-stranded DNA in E. coli after superinfection with helper phage M13K07. Moreover, the lac promoter is located in front of the multiple cloning sites cassette, allowing eventual expression of the cloned genes in E. coli. After mutagenesis and screening of the mutants in E. coli, the plasmids can be readily used to transform Streptomyces spp. As a demonstration, a 3.2-kb DNA fragment containing the gene encoding the xylanase A from Streptomyces lividans 1326 was inserted into pIAFS20, and the promoter region of this gene served as a target for site-directed mutagenesis. The two deletions reported here confirm the efficiency of this new vector as a tool in mutagenesis.

Base Sequence↗
PubMed1992

[Nephroblastomatosis and Wilms' tumor. Apropos of a case].

This case report illustrates the different anatomopathologic patterns and evolutive potentials of perilobar nephroblastomatosis described by Beckwith. The latter differs from those of an intralobar nephroblastomatosis. The evolutive possibilities of nephroblastomatosis underline the importance of imaging technology in the diagnosis and control of such lesions, as well as the role of chemotherapy and above all the caution required in the indications for surgery.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Immunohistochemical detection of cells positive for colony-stimulating factor 1 in lymph nodes from reactive lymphadenitis, and Hodgkin's disease.

Colony-stimulating factor 1 (CSF-1) is a cytokine involved in hematopoiesis and perhaps more importantly in the early stages of immunological defense mechanisms. Although numerous studies of in vitro CSF-1-producing cells have been published, in vivo data is totally lacking. According, we performed immunohistochemical detection of CSF-1-positive cells on frozen sections of reactive lymphadenitis (three cases) and Hodgkin's disease (13 cases) lymph node biopsies, using as antibody a highly specific polyclonal rabbit antiserum prepared in our laboratory. Endothelial cells from high endothelial venules and most fibroblasts were positive in all cases (reactive lymphadenitis and Hodgkin's samples), and most lymphocytes in interfollicular T cell areas showed faint granular positivity in reactive lymphadenitis lymph nodes. Hodgkin and Reed-Sternberg cells were positive in all cases tested, although staining intensity was highly variable and the percentage of positive cells differed from case to case. These data from in vivo biopsies confirm previous results for in vitro CSF-1 production by endothelial cells, fibroblasts, T lymphocytes, and Hodgkin cell lines. They are consistent with the role of this cytokine in immune response and raise the question of its significance in Hodgkin's disease.

Hodgkin Disease↗
PubMed1991

Assignment by in situ hybridization of a fibroblast growth factor receptor gene to human chromosome band 10q26.

A 2.3-kb cDNA probe for the human bek fibroblast growth factor receptor was used to determine the chromosomal localization of the corresponding gene by in situ hybridization. The results show that this gene, a form of which is amplified in some poorly differentiated stomach cancers, is localized on chromosome region 10q26. The two previously identified fibroblast growth factor receptor genes are thus not on the same chromosome, as the related flg ("fms-like gene") fibroblast growth factor receptor gene has previously been mapped to human chromosome region 8p12.

Autoradiography↗
PubMed1991

Progress in outgrowth culture from rabbit tracheal explants: balance between proliferation and maintenance of differentiated state in epithelial cells.

Primary cultures of rabbit tracheal cells were obtained as outgrowths from explants of tracheal mucosa. A 30% collagen substratum containing serum and minimal essential medium was required for obtaining an outgrowth of epithelial cells keeping their differentiated characteristics. The tracheal epithelial cells obtained near the explant in the first days of culture presented morphologic similarities with normal tracheal epithelium. Cultures contained basal cells and epithelial polarized cells that exhibited apical tight junctions and desmosomes. Ciliated cells stayed functional during all time culture. Their number slightly increased at the beginning of the culture and then stayed constant when the total number of cells increased. Development of the outgrowth was rapid and significant inasmuch as the outgrowth surface reached 30 times that of the explant after less than 8 days. This was linked to cellular proliferation, as demonstrated by the incorporation of bromodeoxyuridine (BrdU) in phase-S nuclei and the revelation of BrdU using an immunofluorescence technique. The epithelial nature of the outgrowth cells and the absence of contamination with fibroblasts were established by positive staining with anti-keratin antibody and by negative staining with anti-vimentin antibody, respectively.

Animals↗
PubMed1990

Detection of a biliary cell membrane glycoprotein in the serum of cholangiocarcinoma-bearing rats. Possible relevance to the membrane proteins used as serum tumor markers in humans.

Certain markers used in the diagnosis and monitoring of human adenocarcinomas, such as carcinoembryonic antigen are membrane glycoproteins normally absent from the serum. How those proteins may reach the blood after the neoplastic transformation remains debated. In this work, we show that cholangiocarcinoma induced by 3'-methyl-4-dimethylaminoazobenzene in the rat provides some insight into the mechanisms implicated in this process. We observed that the extracellular matrix of all cholangiocarcinomas tested contained large amounts of a glycoprotein identified by a monoclonal antibody termed B10, and previously characterized as an integral membrane protein normally restricted to the apical domain of epithelial cell plasma membrane. The extracellular deposition of the B10-binding glycoprotein in cholangiocarcinomas was associated with the appearance of detectable levels of the protein in the serum, and an abnormal membrane expression of the protein, which was detected on both apical and basal plasma membrane domains of neoplastic biliary cells. We postulate that neoplastic transformation of biliary cells leads to an inappropriate membrane expression of the B10-binding protein, which in turn, results in the extracellular release of the protein and in its diffusion into the blood. The characteristic desmoplastic stroma of cholangiocarcinoma offers the opportunity to easily visualize the release process. A comparable mechanism is likely to explain how certain membrane glycoproteins used as serum markers in human malignancy may reach the blood.

Adenoma, Bile Duct↗
PubMed1989

Cellular expression of alpha-fetoprotein gene and its relation to albumin gene expression during rat azo-dye hepatocarcinogenesis.

During hepatocarcinogenesis, alpha-fetoprotein (AFP) synthesis may be dramatically increased while albumin synthesis is frequently decreased. Therefore, a reciprocal modulation between both gene expressions has been hypothesized. In this work, we combined in situ hybridization and immunoperoxidase on parallel liver tissue sections in order to analyze at the cellular level, AFP gene expression and its relation to ALB gene expression in both early and neoplastic lesions induced by 3MeDAB in the rat. In early lesions, cell populations were heterogenous as regards AFP expression. High levels of AFP transcripts were detected both in oval type cells and in a subset of basophilic hepatocytes within preneoplastic lesions. In these two highly AFP-expressing cell populations, significant levels of ALB transcripts were concomitantly detected. In the majority of altered hepatocytes, no AFP expression was detected while the level of ALB expression was decreased. In neoplastic lesions, AFP expression was strikingly heterogenous and independent from the degree of morphological differentiation. No evidence of reciprocal modulation with ALB gene expression could be assessed. In both preneoplastic and neoplastic lesions, a few altered hepatocytes displayed significant levels of AFP transcripts while no corresponding protein could be detected; such a discrepancy was not observed for ALB. This work shows that during 3MeDAB hepatocarcinogenesis, AFP gene activation occurs in heterogenous cell populations and according to different cellular patterns. Our observations lend no support to the hypothesis of a reciprocal modulation between AFP and ALB gene expressions during rat azo-dye hepatocarcinogenesis.

Albumins↗