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Biomedical subjects

P Marchand

Publications and source records attributed to P Marchand.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1989

[Esophagectomy without thoracotomy using a stripping method: technic, results, indications in benign and malignant diseases of the esophagus].

A technique of esophagectomy without thoracotomy using a stripper with limited dissection of the mediastinum has been applied to 48 patients: neoplasia in 41 (squamous-cell carcinoma of the esophagus: 34, carcinoma of the gastric cardia: 5, pharyngeal carcinoma: 2) and non-malignant pathology in 7 (2 caustic necroses, 2 ruptured esophagus, 2 anastomotic leakages after gastro-esophageal resection, 1 caustic stenosis). There were 3 post-operative deaths. The best indications of this procedure are extended tumors of the lower esophagus in poor-risk patients, and perhaps superficial carcinomas of the esophagus whatever the site. The usefulness of this technique in such situations as perforations and mediastinitis is emphasized.

Adult↗
PubMed1987

Selective tropism of bovine leukemia virus (BLV) for surface immunoglobulin-bearing ovine B lymphocytes.

Bovine leukemia virus (BLV) is experimentally infectious for sheep. Virus production does not occur in the animals, but only after in vitro cultivation of infected lymphocytes in the presence of phytohemagglutinin. Lipopolysaccharide or dextran sulfate 500 had no effect. After panning separation, it was possible to demonstrate that, in peripheral blood lymphocytes, BLV was integrated in the B lymphocytes only and that BLV expression took place in a fraction of this population. The ovine leukemia may constitute a good experimental model for understanding the virus-induced leukemias of the BLV-human T cell leukemia virus group.

Animals↗
PubMed1987

[Chemoembolization of hepatic metastases. Preliminary study].

Twenty-one patients with hepatic metastases were treated by chemoembolization over a 2-year period, the technique consisting of selective injection of a mixture of Spongel powder and Adriamycin plus 5-FU into the hepatic artery. Indications and results are discussed as a function of clinical, biologic and radiologic criteria.

Adult↗
PubMed1986

[Acute pancreatitis caused by lithiasis in a dilated ampulla of Vater].

Unusual features in a case of dilatation of ampulla of Vater were in the existence of biliary calculi in the diverticulum and lithiasis complicated by a revealing acute pancreatitis. Diagnosis was suggested from barium meal followed through images and confirmed by perioperative cholangiography. Surgical treatment of such cases is simple, allows recovery without sequelae and avoids risks of recurrence.

Acute Disease↗
PubMed1986

[Functional studies of the esophagus in gastroesophageal reflux: application to anti-reflux surgery].

A functional exploration of the esophagus, an acid reflux test, a manometry and an endoscopic examination were performed on 56 patients in succession, who had undergone a complete fundoplication for gastro-esophageal reflux. These tests were done pre-operatively as well as post-operatively at short term (1 year) and long term (4 years). The functional and endoscopic pre-operative work-up did not enable to isolate a group of patients likely to present a therapeutic failure. 54 patients were seen again at 1 year, with a good clinical result in 50 of them (92 per cent). At 4 years, 39 out of 48 patients (81 per cent) maintained that result. The acid reflux test was abnormal in all cases of clinical recurrence. Two asymptomatic patients had an abnormal test. One presented a clinical recurrence subsequently, the other had a severe esophagitis confirming the recurrence. On manometry, a significant and stable increase of the pressure of the lower esophageal sphincter was noticed after fundoplication (8.1 +/- 1.8 mmHg pre-operatively, 15.5 +/- 1.4 mmHg at 1 year, 14.5 +/- 1.5 mmHg at 4 years). In case of recurrence, the pressures were in an average lower although values within normal limits could not exclude a recurrence. A complete fundoplication is therefore a reliable long term procedure. The functional exploration of the esophagus post-operatively enables to select asymptomatic patients with a high recurrence risk and gives an objective evaluation of the operative results.

Adolescent↗