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Biomedical subjects

M Gendreau

Publications and source records attributed to M Gendreau.

14 recordsLinked to original sources
PubMed1994

Conservative management of carpal tunnel syndrome: a reexamination of steroid injection and splinting.

The awareness of carpal tunnel syndrome by the lay public has increased dramatically in recent years, with an apparent shift in patient-population presentation. We prospectively studied steroid injection and wrist splinting in 76 hands in 57 patients, presenting without advanced disease or associated medical conditions, by standard evaluation and protocol of treatment. The average age of the patients was 38 years; 50 women and 7 men were included. Follow-up examination after simultaneous steroid injection and splinting averaged 11 months. Ten hands were noted to be symptom-free at the final evaluation. Women were noted to have a significant decrease in the rate of symptom resolution when compared to men. Patients, 40 years of age or younger, were also noted to have a significant decrease in the rate of symptom resolution when compared to patients over 40 years of age. No significant differences were noted when comparing symptom duration prior to treatment or workers' compensation insurance status to final symptom resolution. Young women are the least likely to have resolution of carpal tunnel syndrome symptoms when treated conservatively.

Adrenal Cortex Hormones↗
PubMed1992

p56lyn catalyzes a reversible autophosphorylation reaction and a nucleoside diphosphate kinase reaction.

The reversible autophosphorylation of the pp60c-src family tyrosine kinase, p56lyn has been characterized by a simple procedure that involves the examination of the enzyme catalyzed radioisotope exchange between ATP and ADP. The equilibrium constant of the reaction was determined to be 3.31 and corresponded to a standard free energy of hydrolysis of the phosphotyrosine bond in p56lyn of -8.08 kcal/mol. GDP was capable of substituting for ADP as phosphate acceptor so that p56lyn displayed a nucleoside diphosphate kinase activity.

ATP Synthetase Complexes↗
PubMed1991

Serial transfer of GVH-R splenomegaly in chicken embryos.

Using histocompatible chicken strains B14 and B19, we demonstrate that the capacity to induce a GVH-R in an embryo could be induced precociously by the reaction itself. While naive chickens display this capacity around 3 to 4 weeks posthatching, embryos engrafted with adult allogeneic cells at E13 or E8 became endowed with this capacity at E20 and E15, respectively. Furthermore, this acceleration could be obtained by serial transfer of splenic cells through a sequence of three embryos undergoing the GVH-R. The highest efficiency in transfer was realized by regularly alternating the MHC haplotype at each transfer. It is concluded that the original cells from the adult donor may be partially responsible for the transfer, but that cells from the successive embryos are also certainly involved. Thus, maturation of the embryonic immune system appears accelerated by a GVH-R.

Age Factors↗
PubMed1991

T-lymphocyte subsets in the embryonic spleen undergoing a graft-versus-host reaction.

Allogeneic immunocompetent T cells injected into chicken embryos induce a graft-versus-host reaction (GVHR) whose most prominent manifestation is splenic hyperplasia. The highly inbred CC and CB strains of chickens used here are, respectively, homozygous for the B4 or B12 MHC haplotypes. By means of a panel of immunological reagents, including alloantisera and monoclonal antibodies against public domains of the T-cell receptor, CD4, CD8, and the inducible interleukin-2-receptor light chain (CD25), it is shown that the bulk of cells in the enlarged spleen are of host origin and do not express markers typical of mature T or B lymphocytes. Among recipient splenocytes, the quantitatively most important population consists of TCR alpha beta-TCR gamma delta- CD4-CD8+CD25+ (TCR0) lymphocytes. Donor cells encountered in the spleen prevalently exhibit a TCR alpha beta+CD4+CD8-CD25+ phenotype and proliferate in vivo. The data demonstrate that nonspecific host and potentially specific donor-derived cellular elements contribute to splenomegaly.

Animals↗
PubMed1989

Ontogeny of the GVH-R inducing capacity, in conventional and germ-free chickens.

Three strains of MHC homozygous chickens were used to study the ontogeny of the GVH-R. It was found that this function of the immune system was acquired with a delay in animals raised in germ-free conditions. In our previous work, we had shown that, contrary to expectation, bursal cells were capable of mounting a GVH-R against embryos, and actually were particularly efficient in this regard when compared to spleen cells. The present experiments have disclosed that splenomegaly induction may be dissociated from the toxic effect that bursal cells also exert on recipient embryos.

Animals↗
PubMed1988

Brain-derived neurotrophic factor stimulates survival and neuronal differentiation in cultured avian neural crest.

The response of trunk neural crest cells taken from precise levels of the neural axis and cultured together with adjacent somites to Brain-derived neurotrophic factor (BDNF), was examined in cultures grown in a chemically defined medium. In control cultures, the number of neural crest-derived neurons expressing the HNK-1 epitope, increased as a function of somitic level in a caudorostral direction. Treatment of cultures with increasing concentrations of BDNF (50 pg/ml to 1 ng/ml) resulted in a 1.5- to 6-fold stimulation in the number of neurons developing from crest cells excised at advanced and post-migratory stages, whereas early migrating crest cells were responsive only to concentrations equal to or higher than 1 ng/ml of BDNF. Nerve growth factor used at 5 and 30 ng/ml had no effect on survival of HNK-1-positive cells at any of the somitic levels tested. In an attempt to identify the subpopulation of HNK-1-immunoreactive neurons responding to BDNF, control and treated cultures were stained for the HNK-1 antibody in combination with substance P (SP) antibodies (as a marker for sensory neurons). SP immunoreactivity localized to a subpopulation of phase-bright, HNK-1-positive neurons. The absolute number of SP-positive neurons increased 2- to 4-fold upon BDNF treatment; however, their relative proportion within the population expressing the HNK-1 epitope remained essentially unchanged from control to treated cultures (on day 1, 20% as compared to 23.3% and on day 2, 44.6% compared to 49.7% for control and treated cultures, respectively). Taken together, these data suggest that BDNF stimulates primary neuronal differentiation of SP expressing neurons, and/or their survival.

Animals↗
PubMed1984

[Separation of the virotoxins of the mushroom Amanita virosa and comparative study of their interaction on actin in vitro].

Cyclic peptides have been extracted with methanol from Amanita virosa and separated by preparative HPLC. Six peptides were obtained: phalloidin and five new peptides recently identified by Faulstich as virotoxins. We have compared the interaction of these six peptides with actin in vitro. They increased the rate of polymerization of actin and protected F-actin against several denaturating agents: proteases, heat, chaotropic ions, cytochalasin B, and DNAse I. The five virotoxins have therefore the same biological properties as phalloidin. However, the differential spectra of interaction between actin and the five virotoxins are different than the differential spectra between actin and phalloidin, thus it appears that the molecular interaction of actin with virotoxins is different than with phalloidin. The five virotoxins have the same activity. Although these virotoxins have different functional groups on amino acids 1 and 7, it is concluded that these two amino acids are of minor importance in the interaction of these peptides with actin.

Actins↗
PubMed1983

Rapid assay of human plasma carboxypeptidase N by high-performance liquid chromatographic separation of hippuryl-lysine and its product.

A rapid and sensitive method for measuring carboxypeptidase N (CPN) activity in human plasma is described. The procedure is based on the hydrolysis of a high-specificity/low-affinity substrate, hippuryl-L-lysine, to its products hippuric acid and lysine. The substrate and product are separated quantitatively by high-performance liquid chromatography in less than 10 min following a minimal sample preparation time. The advantages of this method over previous ones are discussed and data are presented demonstrating the reliability of this method for the routine clinical determination of CPN activity.

Carboxypeptidases↗
PubMed1982

Synthesis of peptides by the solid-phase method. 7. Substance P and analogues.

Substance P and 21 related peptides containing isosteric or isofunctional groups were prepared by the solid-phase method. After purification by gel filtration and ion-exchange chromatography, the compounds were characterized by thin-layer chromatography, paper electrophoresis, and amino acid and elemental analysis. The biological activities of the peptides were evaluated in vitro on the guinea pig ileum, the rabbit mesenteric vein, and the dog common carotid artery and in vivo on the rat blood pressure. It is shown that the replacement of some residues in the undecapeptide substance P causes variable losses of apparent affinity with a little or no change in the intrinsic activity. All the analogues used in the present study were found to be inactive as antagonists.

Animals↗
PubMed1981

Synthesis of peptides by the solid-phase method. 6. Neurotensin, fragments, and analogues.

Neurotensin (NT) and 24 related compounds, including fragments or analogues modified at the C-terminal end of the parent molecule, have been prepared by the solid-phase method. After purification by cation-exchange chromatography, the compounds were characterized by thin-layer chromatography, amino acid analysis, elemental analysis, and high-pressure liquid chromatography. The stimulating effects of the peptides were evaluated in rat stomach strips, in isolated spontaneously beating atria of guinea pigs, and in the coronaries of perfused rat hearts. The differences between the biological activities of these compounds are discussed.

Animals↗
PubMed1980

Synthesis of peptides by the solid-phase method. V. Substance P and analogs.

We have synthesized a series of 12 analogs of the undecapeptide substance P in order to perform a structure-activity study of this peptide. In the present work, each residue was substituted by L-alanine, and the C-terminal amide was replaced by the free carboxyl in order to pinpoint biologically important side chains and functional groups. The synthesis of the analogs was carried out by the automatic solid-phase method. Couplings were performed by the symmetrical anhydride procedure. After cleavage with liquid HF, the peptides were purified by gel filtration and ion-exchange chromatography. Their purity was assessed by thin-layer chromatography, paper electrophoresis, amino acid and elemental analyses, and high pressure liquid chromatography. They were tested for biological activity in vitro on the ileum of the guinea pig, the mesenteric vein of the rabbit, and the vas deferens of the rat, and in vivo by measuring their effect on the blood pressure of the rat.

Animals↗