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Biomedical subjects

P Marchand

Publications and source records attributed to P Marchand.

At least 19 recordsLinked to original sources
PubMed1999

New selective nonsteroidal aromatase inhibitors: synthesis and inhibitory activity of 2,3 or 5-(alpha-azolylbenzyl)-1H-indoles.

Six azolyl substituted indoles were synthesized and tested for their activity to inhibit two P450 enzymes: P450 arom and P450 17a. It was observed that the introduction of alpha-imidazolylbenzyl chain at carbon 3 or 5 on indole nucleus led to very active molecules. Compounds 22, 23 and especially 33 demonstrate very high potential against P450 arom. Under our assay conditions of high substrate concentration the IC50 are 0.057, 0.0785 and 0.041 microM, respectively. These compounds are moderate inhibitors against P450 17alpha.

Aromatase Inhibitors↗
PubMed1998

[Diaphragmatic or juxtadiaphragmatic schwannoma?].

The authors report one case of schwannoma of diaphragmatic topography. This lesion is exceptional and, to our knowledge, only seven cases have been published in the literature. The first diagnosis was a suprarenal tumour. Magnetic resonance imaging provided more detail about the juxta diaphragmatic topography of the tumour, which was subsequently confirmed by surgery. The diagnosis of benign schwannoma was made at the pathological and immuno-histochemical examination of the specimen. The schwannoma corresponded to the type B of the classification of Antoni. Pathogeny and origin of the tumour are discussed. The sympathetic nervous para-vertebral system, the phrenic or intercostal nerves could be the origin of the tumour. In the eight cases reported, the tumoural removal was performed through thoracotomy (n = 5) or laparotomy (n = 3). The preoperative exact location of the juxta diaphragmatic tumours remains difficult to specify.

Adult↗
PubMed1998

N-methyl-N-alkylsilyltrifluoroacetamide-I2 as a new derivatization reagent for anabolic steroid control.

Analytical methods for the control of growth promoters have to be specific and sensitive. At low concentration levels, it is difficult to identify some molecules unambiguously even with the improved performance of analytical methods. GC-MS analysis of 17 beta-trenbolone and its major metabolite, 17 alpha-trenbolone, is a good example. A new derivatization agent has been developed which is based on silylation of the 3- and 17-oxygenated functions and nucleophilic substitution in the 4-position. The structure of the derivatized products was demonstrated using a simple model, cyclohex-2-en-1-one, by NMR and MS spectrometry. In contrast to data found in the literature, this derivative permitted specific mass spectra for trenbolone, sensitive signals for high mass ions and reproducible gas chromatograms to be obtained. The addition of an N(CH3)COCF3 radical to the steroid nucles allowed highly specific detection in GC-high resolution MS even following extraction from complex matrices; sensitive responses were also observed in the negative chemical ionization mode. Moreover, there are significant differences in the electron ionization mass spectra of the two stereoisomers, 17 alpha- and 17 beta-trenbolone. These preliminary results and those obtained for androsta-1,4-dien-3-one and pregna-4,6-dien-3-one indicate useful advances for the determination of steroids and potential applications for metabolism studies on such compounds.

Anabolic Agents↗
PubMed1997

Synthesis and in vitro evaluation of 3-(1-azolylmethyl)-1H-indoles and 3-(1-azolyl-1-phenylmethyl)-1H-indoles as inhibitors of P450 arom.

In the challenge to develop potent inhibitors of aromatase for reducing the levels of estrogens, we found that azolyl-substituted indoles inhibit aromatase activity, 3-(1-Azolylmethyl)-1H-indoles 9-15 and 3-(1-azolyl-1-phenylmethyl)-1H-indoles 22-25 were prepared, and tested on their ability to inhibit P450 arom. Analysis of the inhibitory effect exerted by several derivatives (11, 12, 22, and 23) on microsomal aromatase in vitro activity indicates that azolyl-substituted indoles containing an imidazole moiety are more potent inhibitors than triazole derivatives. In the first series, the introduction of the N-benzyl moiety has been found to enhance the inhibitory profile of these 3-(1-azolylmethyl)-1H-indole derivatives. The corresponding 4-fluoro derivative 12 displays the highest inhibitory activity (IC50 = 0.0718 microM) of all investigated compounds; thus, 12 is 258 times as potent as aminoglutethimide (AG). The presence of a chloro grouping in para position of the phenyl ring in compounds 22 and 24 exerts a positive effect only in the triazol-l-yl sub-series: compound 25 is 4-fold more potent than 24.

Aromatase Inhibitors↗
PubMed1997

Recombinant human 92-kDa type IV collagenase/gelatinase from baculovirus-infected insect cells: expression, purification, and characterization.

Human 92-kDa type IV collagenase/gelatinase (MMP9) has been expressed in insect cells and secreted into the cell medium via a baculovirus expression system. The expression level of the proenzyme from Trichoplusia ni cells was estimated to be > = 300 mg/L of cell medium. The recombinant protein was purified in a single step using heparin-affinity chromatography with an overall yield of ca. 70%. The purified zymogen could be activated in vitro using 4-aminophenylmercuric acetate to yield an active protease. Kinetic analysis of the activated recombinant enzyme demonstrates that this material is comparable to activated MMP9 from natural human sources. The recombinant enzyme provides a useful source of protein for a variety of biochemical and biophysical studies aimed at elucidating the structure and function of human MMP9.

Amino Acid Sequence↗
PubMed1996

Cysteine mutations in the MAM domain result in monomeric meprin and alter stability and activity of the proteinase.

Meprins are oligomeric, glycosylated cell surface or secreted metalloendopeptidases that are composed of multidomain disulfide-linked subunits. To investigate whether subunit oligomerization is critical for intracellular transport or for the enzymatic and/or physical properties of the proteinase, specific cysteine residues were mutated, and the mutants were expressed in 293 cells. Mutation of mouse meprin alpha Cys-320 to Ala in the MAM domain (an extracellular domain found in meprin, A-5 protein, and receptor protein-tyrosine phosphatase mu) resulted in expression of a monomeric form of meprin, as determined by SDS-polyacrylamide gel electrophoresis and nondenaturing gel electrophoresis. The monomeric subunits were considerably more vulnerable to proteolytic degradation and heat inactivation in vitro compared with the oligomeric form of the enzyme. Proteolytic activity of the monomeric meprin using a bradykinin analog or aminobenzoyl-Ala-Ala-Phe-p-nitroanilide as substrate was similar to that of disulfide-linked oligomeric meprin; however, activity against azocasein was markedly decreased. Mutation of another cysteine residue in the MAM domain (C289A), predicted to be involved in intrasubunit disulfide bridging, resulted in disulfide-linked oligomers and monomers. These results indicated that this mutant was capable of forming intersubunit disulfide bonds but less efficiently than wild-type meprin subunits. Mutant C289A also retained activity toward peptides but not the protein substrate and was more vulnerable to proteolytic degradation and heat inactivation compared with the wild-type enzyme. Both Cys mutants were expressed and secreted into the medium at levels comparable with the wild type and had slightly altered glycosylation. This work indicates that 1) Cys-320 of mouse meprin alpha is most likely responsible for the covalent interactions of the subunits; 2) covalent dimerization of subunits is not essential for efficient biosynthesis, trafficking, or posttranslational processing of the secreted protease; and 3) mutations in the MAM domain affect noncovalent interactions of the subunits and the stability and activity of the protease domain, indicating that domain-domain interactions are critical for structure and function of the enzyme.

Animals↗
PubMed1995

COOH-terminal proteolytic processing of secreted and membrane forms of the alpha subunit of the metalloprotease meprin A. Requirement of the I domain for processing in the endoplasmic reticulum.

Cell surface isoforms of meprin A (EC 3.4.24.18) from mice and rats contain beta subunits that are type I integral membrane proteins and alpha subunits that are disulfide-linked to or noncovalently associated with membrane-anchored meprin subunits. Both alpha and beta subunits are synthesized with COOH-terminal domains predicted to be cytoplasmic, transmembrane, and epidermal growth factor-like; these domains are retained in beta subunits but are removed from alpha during maturation. The present studies establish that an inserted 56-amino acid domain (the "I" domain), present in alpha but not in beta, is necessary and sufficient for COOH-terminal proteolytic processing of the alpha subunit. This was demonstrated by expression of mutant meprin subunits (deletion mutants, chimeric alpha beta subunits, and beta mutants containing the I domain) in COS-1 cells. Mutations of two common processing sites present in the I domain (a dibasic site and a furin site) did not prevent COOH-terminal proteolytic processing, indicating that the proteases responsible for cleavage are distinct from those having these specificities. Deletion of the I domain from the alpha subunit resulted in accumulation of unprocessed subunits in a preGolgi compartment. Furthermore, COOH-terminal proteolytic processing of wild-type alpha subunits occurred before acquisition of endoglycosidase H resistance. Pulse-chase experiments and expression of an alpha subunit transcript containing a c-myc epitope tag, confirmed that proteolytic processing at the COOH terminus occurs in the endoplasmic reticulum. This work identifies the region of the alpha subunit that is essential for COOH-terminal processing and demonstrates that the differential processing of the evolutionarily-related subunits of meprin A that results in a structurally unique tetrameric protease begins in the endoplasmic reticulum.

Amino Acid Sequence↗
PubMed1995

[Major liver injury. Role of preoperative transcutaneous endoluminal aortic clamping].

Severe contusion of the liver (type V in the Moore and Flint classification) still has a very poor prognosis. Exsanguination may lead to cardiac arrest when the abdomen is opened. Three patients with major liver injury were treated after percutaneous intra-aortic balloon occlusion and complete vascular exclusion of the liver. Two patients survived and one died due to complications resulting from lung trauma. The aorta was occluded with a balloon catheter inserted via the femoral route. The hepatic vascular exclusion was performed surgically after resuscitation had reestablished a satisfactory haemodynamic situation. Liver resection could then be performed under safe conditions. Aortic occlusion is a simple procedure with minimal disadvantages which could improve prognosis of major liver contusion by reducing the rate of intra-operative death.

Aorta↗
PubMed1995

Disruption of murine Hexa gene leads to enzymatic deficiency and to neuronal lysosomal storage, similar to that observed in Tay-Sachs disease.

Tay-Sachs disease is an autosomal recessive lysosomal storage disease caused by beta-hexosaminidase A deficiency and leads to death in early childhood. The disease results from mutations in the HEXA gene, which codes for the alpha chain of beta-hexosaminidase. The castastrophic neurodegenerative progression of the disease is thought to be a consequence of massive neuronal accumulation of GM2 ganglioside and related glycolipids in the brain and nervous system of the patients. Fuller understanding of the pathogenesis and the development of therapeutic procedures have both suffered from the lack of an animal model. We have used gene targeting in embryonic stem (ES) cells to disrupt the mouse Hexa gene. Mice homozygous for the disrupted allele mimic several biochemical and histological features of human Tay-Sachs disease. Hexa-/- mice displayed a total deficiency of beta-hexosaminidase A activity, and membranous cytoplasmic inclusions typical of GM2 gangliosidoses were found in the cytoplasm of their neurons. However, while the number of storage neurons increased with age, it remained low compared with that found in human, and no apparent motor or behavioral disorders could be observed. This suggests that the presence of beta-hexosaminidase A is not an absolute requirement of ganglioside degradation in mice. These mice should help us to understand several aspects of the disease as well as the physiological functions of hexosaminidase in mice. They should also provide a valuable animal model in which to test new forms of therapy, and in particular gene delivery into the central nervous system.

Animals↗
PubMed1995

Dialog organization and functional communication in a medical assistance task by phone.

This study is based on a corpus of 110 dialogs recorded in a medical assistance telephonist's workstation. Given the nature of the task, we have considered five main variables in dialog (topics) as well as their order of occurrence (sequences). These data were analyzed with a lexical analysis program. Results show a great difference between Operator/Specialist dialog and Operator/Nonspecialist dialog. Dialog "script" is very strong in the first case in which the operator merely plays a feedback role (routine procedures). If the caller is a private individual, the situation is often an indefinite problem, and the operator may have to adapt to the person (weak script) to obtain relevant information as quickly as possible (problem-solving procedures). This provides confirmation of the operator's twofold competence (efficient decision-making, dialog management).

Humans↗
PubMed1994

Membrane association and oligomeric organization of the alpha and beta subunits of mouse meprin A.

Meprins are oligomeric cell surface metalloproteinases of the "astacin family." They consist of two types of subunits (alpha and beta), which are evolutionarily related and whose cDNA sequences predict a similar domain structure. The present work shows that reducing agents solubilized meprin alpha subunits (approximately 90%), but not beta subunits, from mouse kidney brush border membranes. In addition, immunoblotting of membranes or purified meprins with an antibody raised to the alpha subunit epidermal growth factor-like domain, predicted to be near the COOH terminus from the cDNA-deduced amino acid sequence, indicated that this domain is not present in the mature alpha subunit. By contrast, an epitope predicted to be near the COOH terminus of the beta subunit was present in the mature form of beta. When meprins were solubilized from brush border membranes by papain, the size of the alpha subunit (approximately 90 kDa) did not change, while the beta subunit decreased from 110 to 90 kDa with concomitant loss of the COOH-terminal epitope. These data indicate that beta is a type I transmembrane protein, while alpha does not transverse the membrane and its association is dependent on disulfide bonds. The oligomeric organization of purified meprin A (EC 3.4.24.18), examined by sedimentation equilibrium analysis and native gradient gel electrophoresis, is that of disulfide-bridged dimers which aggregate noncovalently to form higher molecular weight complexes, predominantly tetramers. Western blotting of ICR kidney brush border membrane proteins identified alpha 2 homodimers and alpha beta heterodimers. Treatment of mouse or rat kidney brush border membranes with 7 M urea solubilized alpha 2, but not alpha beta dimers. Thus, the mature alpha subunit exists in alpha 2 and alpha beta disulfide-linked dimers which form tetramers, and the alpha 2 homodimers associate with the membrane through noncovalent interactions with alpha beta.

Amino Acid Sequence↗
PubMed1994

Developments in residue assay and metabolism study of growth-promoters by mass spectrometric analysis.

The French national reference laboratory, for the control of growth-promoter residues, has developed routine methods of multiresidue analysis. These are mainly for the determination of beta-agonistic and steroid compounds. Apart from this regulatory activity, some research into growth-premotor metabolism and assay has also been carried out. This research concerns the method development of assay and metabolism studies of new compounds, including in vitro metabolism studies on cell (mainly hepatocytes) cultures, as well as studying the organic synthesis of new compounds and metabolites. Three examples of the different areas of research are presented here: the metabolism study of 4-chlorotestosterone in cattle; a methodological study on beta-agonists assay by mass spectrometry; and a residue study of beta-agonists in edible tissues.

Adrenergic beta-Agonists↗
PubMed1993

Cloning, expression, and chromosomal localization of the mouse meprin beta subunit.

Meprins are plasma membrane homo- or hetero-oligomeric metalloendopeptidases that contain glycosylated alpha and/or beta subunits. This paper reports the cloning and sequencing of the mouse kidney beta subunit. The primary translation product is composed of 704 amino acids which includes a transient signal sequence of 20 amino acids at the NH2 terminus. The protease domain (Asn-63 to Leu-260) contains the putative zinc-binding motif characteristic of metalloendopeptidases of the "astacin family." The COOH terminus contains an epidermal growth factor-like domain, a potential membrane-spanning domain, and an additional 26 amino acids. The beta subunit has an overall 42% identity to the alpha subunit, however, a 56-amino acid segment near the COOH terminus of alpha is missing in beta, and the putative transmembrane and cytoplasmic domains of the subunits share no significant sequence similarity. NH2-terminal analyses of detergent-solubilized mature forms revealed that, unlike alpha, the prosequence (Leu-21 to Lys-62) is not removed from the beta subunit. Northern blot analysis revealed a 2.5-kilobase message for the beta subunit in the kidney and intestine of C57BL/6 and C3H/He mice. The gene for the beta subunit was localized to mouse chromosome 18. These studies indicate that alpha and beta probably derived from a common ancestral gene, but have evolved so that their genes are on two different chromosomes, and their tissue-specific expression and post-translational processing differ.

Amino Acid Sequence↗
PubMed1993

Desmin sequence elements regulating skeletal muscle-specific expression in transgenic mice.

During the development of the mouse embryo, desmin is one of the first muscle proteins detected in both the heart and the somites. The expression of the desmin gene differs from most other muscle genes, since it is initiated in replicating myoblasts and accumulates as the muscle differentiates. We have characterized a muscle-specific enhancer which directs the expression of desmin in vitro in the myoblasts and myotubes of C2 cells but not in non-myogenic cells. We report here on the generation and characterization of transgenic mice bearing a transgene in which the 1 kb DNA 5' regulatory sequence of the desmin gene is linked to a reporter gene coding for Escherichia coli beta-galactosidase (Des1-nlacZ). The enhancer activity of the desmin promoter is very strong and the reporter gene expression is easily detected in tissue sections. We have demonstrated that the regulatory elements present in the transgene Des1-nlacZ are sufficient to direct muscle-specific and developmentally regulated expression of nlacZ in skeletal muscles. Endogenous desmin expression and transgene activity were found to be correlated during the development of skeletal muscles. The transgene was expressed in the committed mononucleate myoblasts as well as in the myotubes. In addition, we have shown that the desmin-derived sequences direct a highly selective expression of nlacZ in cells that leave the somites and invade the limb bud, indicating that the cells that migrate from the somites are already predetermined for myogenesis. In contrast, smooth and cardiac muscle cells were beta-galactosidase negative both during embryonic and foetal development. Interestingly, the transgene was found to be expressed in the conduction system of the heart, which exhibits many features characteristic of skeletal muscles.

Animals↗
PubMed1992

The MgATP-binding site on chicken gizzard myosin light chain kinase remains open and functionally competent during the calmodulin-dependent activation-inactivation cycle of the enzyme.

An ATP-like affinity labeling reagent, 5'-[p-(fluorosulfonyl)benzoyl]adenosine (FSBA), was used to probe the MgATP-binding site of smooth muscle myosin light chain kinase from chicken gizzard (smMLCK) and its calmodulin (CaM) complex. Native smMLCK has an absolute requirement for the binding of the calcium complex of CaM for expression of its catalytic activity. FSBA reacted with smMLCK-CaM and with the CaM-free, inactive enzyme as well. Both reactions were dependent on time and FSBA concentration. Reaction was accompanied by the incorporation of covalently bound [14C]FSBA into smMLCK protein at a molar ratio of approximately 1:1 in each case. p-(Fluorosulfonyl)benzoic acid, an analogue of FSBA lacking the adenosine targeting group, did not react at a significant rate with either form of smMLCK. Reaction of CaM-free and CaM-bound smMLCK with FSBA displayed saturation kinetics. The first-order rate constants for the conversion of the reversible, noncovalent enzyme-FSBA complex to form the irreversibly inhibited, covalently modified enzyme were similar for both smMLCK and smMLCK-CaM, 0.15 and 0.07 min-1, respectively. The concentrations of FSBA yielding the half-maximal rate of inactivation, KI, were essentially identical--0.65 and 0.64 mM, respectively--for smMLCK and smMLCK-CaM. MgATP, but not MgGTP or a substrate peptide, potently inhibited reaction with FSBA. Inhibition by MgATP was competitive. The measured inhibitory constant for MgATP was essentially the same--33 versus 34 microM--for both smMLCK and smMLCK-CaM. It therefore is concluded that the MgATP-binding site on smMLCK remains accessible and recognizable as such when the enzyme becomes inactivated upon dissociation of CaM.

Adenosine Triphosphate↗
PubMed1992

Rapid diagnosis of influenza A. Comparison with ELISA immunocapture and culture.

The Directigen Flu-A is an enzyme immunoassay for detecting in 15 min the influenza A nucleoproteinic antigen directly from specimens after passive adsorption on a cellulose membrane. The test was assessed using 160 frozen (-20 degrees C) specimens collected during the 1988-1989 A/H1N1 influenza epidemic and the 1989-1990 A/H3N2 epidemic. Compared to the ELISA immunocapture test, the sensitivity of the commercial test was 87.8% and the specificity was 97.6%. When compared to isolation of viruses on LLCMK2 cells and/or chicken embryo, the sensitivity was 84%. No cross-reaction was found with other respiratory disease viruses. The feasibility, practicability and rapidity of the test make it a test of choice for rapid diagnosis of influenza A.

Antigens, Viral↗
PubMed1991

Comparative study of biosynthetic human growth hormone immunogenicity in growth hormone deficient children.

The immunogenicities of six recombinant human growth hormone (rhGH) preparations, from KABI (A rhGH191 and B rhGH192), Eli Lilly (C), Nordisk (D), Sanofi (E) and Serono (F), used to treat 260 GH-deficient children, have been compared using a common specific and sensitive procedure for antibody determination. For this purpose we developed two immunoassays: a competitive liquid radioimmunoassay using 125I-rhGH, and an immunometric solid enzymoimmunoassay in which the rhGHs were immobilized. Blood samples were collected from the GH-deficient children before treatment and after 3, 6, 9, 12, 18 and 24 months of therapy. Human GH antibodies were detected in children treated with 3 of the 6 rhGH preparations. Seven percent of the patients treated with hormone A, 14% with hormone B and 22% with hormone C formed antibodies against the respective rhGH. Differences in capacity and affinity of the hGH antibodies were observed between these anti-GH-positive groups. They could be divided into 2 groups according to their immunopotency. One group (7, 14 and 6% of the patients treated with hormones A, B and C, respectively) developed anti-hGH antibodies with very low binding capacities (30-100 fmol/ml). The other group (16% of the patients treated with hormone C) developed IgG-type antibodies to hGH with higher binding capacities (200-1,200 fmol/ml) and a measurable binding affinity (Ka = 10(8) M-1). These hGH antibodies partially inhibited the binding of labeled GH to its specific liver membrane receptor. However, because of their low titer, they did not inhibit growth in the treated children.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗