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G Merlin

Publications and source records attributed to G Merlin.

At least 37 records · Page 2Linked to original sources
PubMed1991

[Responsibility of psychotropic drugs in road accidents].

Serum concentrations of psychotropic drugs were measured in 363 drivers injured in road accidents and admitted to the emergency department of Angers regional university hospital. The figures obtained were correlated to the presumed responsibility of each driver in the accident. Benzodiazepines and phenobarbitone were found in the serum of 39 drivers, and responsibility was significantly increased in this group. The role played by these medicines in road accidents has often been alluded to in the literature, but the value of these previous studies was limited by the lack of quantitative assays. Measuring serum concentrations has permitted a more accurate analysis of the relationship between responsibility for road accident and consumption of psychotropic drugs, including barbiturates. This has prompted the authors to organize a regional information campaign intended for the general public and doctors and aimed at drawing attention to the higher risk of accident among road users taking these drugs.

Accidents, Traffic↗
PubMed1991

Induction of HLA-DR by interferon-gamma requires a trypsin-like protease.

Induction of HLA-DR antigen expression by interferon-gamma (IFN-gamma) is inhibited by trypsin inhibitors and an anti-trypsin monoclonal antibody, but not by chymotrypsin inhibitors, suggesting a requirement for trypsin-like protease (TLP) activity in IFN-gamma-induced HLA-DR expression. Using p-nitroanilide and thioester substrates, TLP activity was demonstrated in cellular extracts of a hybrid epidermal cell line and judged to be essential for HLA-DR expression. TLP activity was inhibited by the trypsin inhibitors soybean trypsin inhibitor, ovomucoid trypsin inhibitor, and tosyl-lysyl-chloromethyl ketone and by an anti-trypsin monoclonal antibody, closely paralleling inhibition of HLA-DR expression by such agents. TLP activity was enhanced by exposure to trypsin-linked agarose, indicating that the protease normally exists in an inactive form, perhaps in an enzyme-inhibitor complex or as an activatable proenzyme. Finding glucocorticoids (GC) to also inhibit IFN-gamma-induced HLA-DR expression and to regulate serine protease, especially urokinase plasminogen activator (uPA), activity raised the possibility of GC regulation of TLP activity. However, TLP activity was found to be constitutively expressed, regulated by neither GC nor IFN-gamma, nor was uPA activity involved in HLA-DR regulation. Trypsin inhibitors and GC also inhibited induction of intracellular 2',5'-oligoadenylate (2-5A) synthetase by IFN-gamma. Thus, TLP activity is required for IFN-gamma induction of HLA-DR and 2-5A synthetase.

2',5'-Oligoadenylate Synthetase↗
PubMed1990

Rapid increase of the human IFN-gamma receptor phosphorylation in response to human IFN-gamma and phorbol myristate acetate. Involvement of different serine/threonine kinases.

Various cell surface receptors are phosphorylated upon binding of their ligand, and this phosphorylation seems to be involved in the signal transduction or in the feedback regulation of this signal. The possibility of a phosphorylation of the human IFN-gamma receptor (hu-IFN-gamma-R) has been investigated with 32P-labeled whole Raji cells and receptor purification either by immunoprecipitation with an anti-hu-IFN-gamma-R polyclonal antiserum or by affinity chromatography. The hu-IFN-gamma-R was found to be phosphorylated at a basal level. Upon incubation of the cells with recombinant hu-IFN-gamma, a dose-dependent two-fold increase of this phosphorylation was observed. Phosphoamino acid analysis by TLC showed that the same amino acids, serine and threonine, are phosphorylated at a basal level and after incubation with hu-IFN-gamma. Protein kinase C and Ca2+/calmodulin-dependent kinase pathways have been reported in some cases to be involved in the signal transduction pathway of hu-IFN-gamma. Both pathways involved the activation of a serine/threonine kinase and therefore we have investigated the possibility of hu-IFN-gamma-R phosphorylation by these kinases. PMA, an activator of protein kinase C, induced a rapid increase of the receptor phosphorylation in Raji cells, whereas the Ca2+ ionophore A23187 did not. PMA-induced hu-IFN-gamma-R phosphorylation was not associated with any effect on expression or inactivation of the receptor. PMA alone did not mimic the hu-IFN-gamma effect in Raji cells as measured by induction of IP-10 gene expression, a high specific marker of hu-IFN-gamma response. But the protein kinase C inhibitors, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7) and staurosporine, reduced this IFN-gamma-induced expression. However, H7 and staurosporine treatment as well as protein kinase C depletion suppressed PMA-induced receptor phosphorylation, whereas constitutive and hu-IFN-gamma-induced phosphorylation remained unchanged. Our results suggest that the serine/threonine kinase involved in the hu-IFN-gamma-R phosphorylation induced by IFN-gamma is different from protein kinase C.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1990

Differential regulation of the human IFN-gamma receptor expression in Raji and IM9 lymphoblastoid cells versus THP-1 monocytic cells by IFN-gamma and phorbol myristate acetate.

Expression of the human (hu) IFN-gamma-R has been studied in Raji and IM9 cells (two B lymphoblastoid cell lines) and in THP-1 cells (a monocytic cell line) with respect to IFN-gamma binding sites, receptor protein and mRNA levels. Although, in these three cell lines, the hu-IFN-gamma-R mRNA was expressed to the same extent, the high affinity receptor was expressed differently both in cell surface receptor binding and amount of receptor protein. Various ligands are able to modulate the expression of their own receptor. We investigated the modulation of the hu-IFN-gamma-R by its ligand. Hu-IFN-gamma induced a rapid and dose-dependent decrease of its cell surface receptor number without alteration of receptor affinity, amounts of receptor protein or hu-IFN-gamma-R mRNA accumulation and stability. Thus, in Raji, IM9, and THP-1 cells, the hu-IFN-gamma had no effect on its receptor gene expression and the cell surface decrease was simply due to ligand blocking and receptor internalization rather than true down-regulation. The second messenger in the hu-IFN-gamma signal transduction pathway is not well characterized, but activation of protein kinase C has been reported in some cases. Therefore, the modulation of the hu-IFN-gamma-R expression by PMA, a potent activator of protein kinase C and a modulator of other receptor expression, has been investigated. In Raji and IM9 cells, PMA had no or few effects on the cell surface receptor number and no detectable effect on the receptor protein or on mRNA levels. In contrast, in THP-1 cells, PMA treatment induced a time and dose-dependent five- to sixfold increase of the cell surface receptors due to a rapid and persistent increase of the hu-IFN-gamma-R gene expression in THP-1 cells was specifically inhibited or reversed by hu-IFN-gamma treatment. The modulation of the hu-IFN-gamma-R expression by PMA in THP-1 cells and by hu-IFN-gamma in PMA-treated THP-1 cells seems associated with their effect on monocyte-macrophage differentiation and/or macrophage activation.

Blotting, Northern↗
PubMed1990

[Traumatic infarction of the right ventricle caused by coronary dissection].

A case is reported of a 47 year-old man who suffered from a right ventricular myocardial infarct which occurred as a result of right coronary arterial dissection after non-penetrating anteroposterior chest compression. The patient was admitted with right heart failure and a central venous pressure of 17 cm H2O. The ST segment in leads V1 to V3 (V2: 7mm) was significantly elevated. Echocardiography showed dilatation of both right atrium and ventricle, with a deviated septum. Emergency cardiac angiography confirmed a hypokinetic right ventricle, with no other abnormal finding. Coronary angiography, performed 24 h after admission, revealed a dissection of the second part of the right coronary artery, with a normal left coronary system which reperfused that part of the right coronary arterial territory located beyond the dissection. The ST segment elevation stopped at the 10th hour. Initially, the patient's condition worsened. Thereafter, he slowly improved under treatment (5.5 micrograms.kg-1.min-1 dobutamine, and fluids so as to maintain a pulmonary wedged pressure of about 15 mmHg). As post-traumatic myocardial infarction is rare, the diagnostic and therapeutic strategies are discussed.

Coronary Angiography↗
PubMed1989

Cloning of murine interferon gamma receptor cDNA: expression in human cells mediates high-affinity binding but is not sufficient to confer sensitivity to murine interferon gamma.

A full-length cDNA encoding the murine interferon gamma (IFN-gamma) receptor was isolated from a lambda gt11 library using a human IFN-gamma receptor cDNA probe. The deduced amino acid sequence of the murine IFN-gamma receptor shows approximately 53% homology to its human counterpart but no homology to other known proteins. Murine IFN-gamma receptor cDNA was expressed in human HEp-2 cells, which do not bind murine IFN-gamma and are insensitive to its action. Transfectants displayed the same binding properties as mouse cells. The biological responsiveness of such transfectants to various biological effects of both human and murine IFN-gamma was investigated, including modulation of major histocompatibility complex class I and class II antigen expression, inhibition of cell growth, and antiviral activity. Like parental HEp-2 cells, these transfectants responded only to human, but not to murine, IFN-gamma. Inversely, mouse L929 cells transfected with human IFN-gamma receptor cDNA were insensitive to human IFN-gamma. These results confirm and extend previous findings, suggesting that species-specific cofactors are needed for IFN-gamma-mediated signal transduction.

Amino Acid Sequence↗
PubMed1989

Molecular characterization of the human interferon-gamma receptor: analysis of polymorphism and glycosylation.

Different molecular masses have been assigned to the human interferon-gamma receptor (HuIFN-gamma-R) by several authors. After extensive purification from Raji cells, this receptor was shown in a previous work to consist of two major protein species with molecular masses of 92 kD and 50 kD, as revealed by SDS-PAGE. We show here that the 50-kD band is most probably a degradation product of the 92-kD band due to a trypsin-like protease active during the purification process. The native protein of Raji cells seems, therefore, to have a molecular mass of 92 kD. The same molecular mass was found with Colo 205 cells (derived from a colon carcinoma). However, in conditions where degradation does not occur, the HuIFN-gamma-R shows a certain polymorphism: in IM-9 cells, another B-cell line, two bands exist with molecular masses of 95 kD and 85 kD, and in Wish cells, an amnion-derived cell line, one (or two) band(s) can be detected around 87 kD. This polymorphism is due at least in part to a variable extent of N-glycosylation from line to line and also within the same line, since after tunicamycin treatment of the Raji, IM-9, and Wish cells, very similar bands are obtained with a molecular mass of 72 kD.

Blotting, Western↗
PubMed1988

Molecular cloning and expression of the human interferon-gamma receptor.

A cDNA encoding the human interferon-gamma receptor was isolated from a lambda gt11 expression library using a polyclonal antireceptor antiserum. The gene for this receptor was identified in a cosmid library and transfected into mouse cells. The human interferon-gamma receptor expressed in mouse cells displayed the same binding properties as in human cells. However, transfected cells were not sensitive to human IFN-gamma, suggesting the need for species-specific cofactors in receptor function. As inferred from the cDNA sequence, the human interferon-gamma receptor shows no similarities to known proteins and represents a novel transmembrane receptor. It is most likely the product of a single mRNA and a gene located on chromosome 6q.

Amino Acid Sequence↗
PubMed1988

High affinity human IFN-gamma-binding capacity is encoded by a single receptor gene located in proximity to c-ros on human chromosome region 6q16 to 6q22.

We have used human-rodent somatic cell hybrids to investigate the regional localization of the IFN-gamma R gene on human chromosome 6 and studied functional and antigenic characteristics of the expressed IFN-gamma R by Scatchard analyses of 125I-IFN-gamma binding and binding of an anti-receptor mAb (A6C5). The data obtained revealed coordinate expression of IFN-gamma- and A6C5-binding capacity as well as competition in binding to chromosome 6-positive hybrids and normal cells, indicating that the A6C5-defined protein is by itself capable of high affinity IFN-gamma binding and, thus, is likely to constitute the major IFN-gamma R protein of distinct cell types. The receptor gene could be allocated to region 6q16 to 6q22, which also contains the c-ros oncogene. Genetic linkage of the IFN-gamma R gene to an oncogene located in a region of non-random chromosomal aberrations may have a causal relationship to the deregulated IFN-gamma R expression in several malignancies.

Antibodies, Monoclonal↗
PubMed1987

Purification of human gamma interferon receptors by sequential affinity chromatography on immobilized monoclonal antireceptor antibodies and human gamma interferon.

mAbs against human IFN-gamma (huIFN-gamma) receptors were obtained by immunizing a BALB/c mouse with eluates from immobilized recombinant huIFN-gamma (rhuIFN-gamma) on which lysates of enriched Raji cell membranes had been adsorbed. mAbs were selected for competitive inhibition of receptor binding of 125I-labeled rhuIFN-gamma. The following additional properties suggest that these antibodies are specific for huIFN-gamma receptors: they bind to the surface of human cells expressing IFN-gamma receptors but not to heterologous cells; this binding is inhibited competitively by addition of rhuIFN-gamma; the number of binding sites revealed by direct binding of 125I-labeled rhuIFN-gamma correlates with the amount of antigen recognized by the mAbs on different cell lines. A Triton X-100 extract of a membrane-enriched fraction of human Raji cells was affinity purified with these mAbs and the eluates from such columns were further purified on immobilized rhuIFN-gamma. As revealed by SDS-PAGE, the final eluate contained two major protein bands with approximate Mr of 90,000 (p90) and 50,000 (p50), respectively. Both proteins were able to specifically bind 125I-labeled rhuIFN-gamma upon electroblotting to nitrocellulose. This binding could be inhibited by the huIFN-gamma receptor mAbs, suggesting that the same epitopes are recognized on p90, p50, and on the cell surface. Therefore, these proteins most likely represent at least a part of huIFN-gamma receptors.

Animals↗
PubMed1985

3' end structure of the human (2'-5') oligo A synthetase gene: prediction of two distinct proteins with cell type-specific expression.

Analysis of the sizes of the (2'-5') oligo A synthetase polyadenylated transcripts in various human cell lines by hybridization with a cDNA probe revealed that the pattern of the transcripts was cell-type specific. In order to investigate whether the 1.6 Kb, 1.8 Kb and 3.6 Kb mRNA, which are predominantly expressed in different cell-lines, encode different proteins or could differ in the size of their 3' or 5' untranslated sequences, the corresponding gene was isolated. On Southern blots of human genomic RNA, the cDNA probe hybridize to a 3.1 Kb EcoRI fragment. Three overlapping genomic clones were isolated which contain the same 3.1 Kb EcoRI fragment. Transcriptional mapping of the 3' end of the gene by Northern blots, hybridization translation experiments and sequencing showed that the 1.6 and 1.8 Kb mRNA are produced by a differential processing at the 3' end of the primary transcript of the same gene. The polyadenylation site of the 1.6 Kb mRNA is located 1.9 Kb upstream to the one of the 1.8 Kb mRNA. To produce the latter transcript, a portion of the last exon of the 1.6 Kb mRNA (including a segment coding for a very hydrophobic sequence of 18 amino acids and 3' untranslated sequence) is spliced out. The two mRNAs thus encode two different proteins which could have different affinity for cellular elements. The 3.6 Kb transcript has the same polyadenylation site as the 1.8 Kb mRNA, but contains additional unspliced 3' intron sequences.

2',5'-Oligoadenylate Synthetase↗
PubMed1985

125I-labelled human interferons alpha, beta and gamma: comparative receptor-binding data.

Binding of 125I-labelled human recombinant DNA interferons (IFNs) alpha-2, beta and gamma was compared on various human lymphoid cells and embryonic fibroblasts. While binding constants were within an order of magnitude for all three interferons (10(-10) to 10(-9) M), no competition was observed between IFN-gamma on the one hand and IFN-alpha 2 and IFN-beta on the other. However, consistent with previous reports, IFN-alpha 2 and IFN-beta competed for presumably common receptors. Depending on the cell type, binding sites for IFN-gamma were expressed in different numbers compared to those for IFN-alpha 2 and IFN-beta. These direct comparative binding studies support the hypothesis that the receptor system for IFN-gamma is unrelated to the IFN-alpha/beta system.

Binding Sites↗
PubMed1985

[Demonstration of 2-5A synthetase in human circulating mononuclear cells after oral administration of an interferon inducer isolated from a fraction of Escherichia coli and Klebsiella pneumoniae].

Evaluation of the activity of an enzyme activated by interferon (2'-5' oligo-isoadenylate synthetase or 2-5A synthetase) has been used to determine, in man, the interferon inducing capacity of a fraction isolated from Escherichia coli and Klebsiella pneumoniae, SL04, an immunomodulating agent administrated per os. An increase of the activity of this enzyme has been shown in four out of five volunteers following a single oral administration of 100 mg of SL04. This activation demonstrated in humans confirms the pharmacological results of the interferon induction obtained with SL04 in vivo in mice and in vitro in human cell cultures.

2',5'-Oligoadenylate Synthetase↗
PubMed1984

(2'-5') Oligo A synthetase in human polymorphonuclear cells increased activity in interferon treatment and in viral infections.

The interferon (IFN)-induced enzyme 2-5A synthetase was found in human peripheral blood polymorphonuclear cells (PMNL). The average enzyme activity in a group of 15 patients with various viral infections was significantly higher (25-fold) than in healthy individuals. Eight patients with multiple sclerosis and six patients with bacterial infections were found to have normal 2-5A synthetase levels in the PMNL. Relationship of PMNL 2-5A synthetase levels to IFN was confirmed by finding enzyme increases in PMNL incubated in vitro with IFN, as well as in patients undergoing IFN therapy. These findings suggest that in PMNL, as in other cells, the level of 2-5A synthetase can be regulated by IFN and can be increased as a result of IFN information in diseases.

2',5'-Oligoadenylate Synthetase↗
PubMed1983

Interferon-induced 56,000 Mr protein and its mRNA in human cells: molecular cloning and partial sequence of the cDNA.

Treatment of responsive cells by interferons (IFNs) induces within a few hours a rise in the concentration of several proteins and mRNAs. In order to characterize these IFN-induced mRNA species, we have cloned in E. coli the cDNA made from a 17-18S poly(A)+ RNA of human fibroblastoid cells (SV80) treated with IFN-beta. We describe here a pBR322 recombinant plasmid (C56) which contains a 400 bp cDNA insert corresponding to a 18S mRNA species newly induced by IFN. The C56 mRNA codes for a 56,000 dalton protein easily detectable by hybridization-translation experiments. The sequence of 66 of the carboxy-terminal amino-acids of the protein can be deduced from the cDNA sequence. IFNs-alpha, beta or gamma are able to activate the expression of this gene in human fibroblasts as well as lymphoblastoid cells. The mRNA is not detectable without IFN; it reaches maximum levels (0.1% of the total poly(A)+ RNA) within 4-8 hrs and decreases after 16 hrs.

Amino Acid Sequence↗
PubMed1983

Molecular cloning and sequence of partial cDNA for interferon-induced (2'-5')oligo(A) synthetase mRNA from human cells.

By using a translation assay in oocytes, a 17S RNA fraction coding for the interferon-induced (2'-5')oligo(A) synthetase was purified from human cells. A cDNA library was prepared by cloning in Escherichia coli plasmid pBR322 and screened by positive hybridization-translation in oocytes. A cDNA clone corresponding to the (2'-5')oligo(A) synthetase mRNA was identified. In SV80 cells, this E cDNA recognizes three RNAs of 1.65, 1.85, and 3.6 kilobases, which are present only after interferon treatment of the cells. In Namalva cells, mainly one RNA of 1.8 kilobases is seen.

2',5'-Oligoadenylate Synthetase↗