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Biomedical subjects

J Magnan

Publications and source records attributed to J Magnan.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1979

Studies on the inhibitory action of somatostatin in the electrically stimulated rat vas deferens.

Somatostatin (SS) inhibits in a dose-dependent manner electrically evoked contractions in the rat vas deferens. This action was not modified by yohimbine, naloxone or a mixture of antagonists containing atropine, phentolamine, methysergide, burimamide, propranolol and indomethacin, but was markedly potentiated by reducing the Ca2+ concentration of the medium from 2.5 to 1.25 mM and greatly inhibited when increasing the Ca2+ concentration of the medium from 2.5 to 5.0 mM. Clonidine (CLO), but not beta-endorphin (ENDO) was affected similarly to SS by changing the Ca2+ concentration of the medium. The contractile effect of norepinephrine in unstimulated rat vas deferens was not altered by SS. These results were taken as an indication that SS produces its inhibitory action in the rat vas deferens by interacting with specific SS and its receptors presumably located in the cell membranes of adrenergic nerve terminals. The interaction between SS and its receptors may provoke a decreased diffusion of Ca2+ ions into the nerve terminals and/or a decreased mobilisation of Ca2+ ions from intraneuronal stores thus leading to a reduction in electrically evoked release of norepinephrine.

Animals↗
PubMed1978

Rat vas deferens: a specific bioassay for endogenous opioid peptides.

The electrically-evoked contractions of the rat vas deferens were selectively inhibited by beta-endorphin, the preparation being much less sensitive to enkephalins and narcotic analgesic drugs. However, introduction of D-Ala in position 2 of [Leu]-enkephalin enhanced the activity of the opioid peptide to the order of that of beta-endorphin. It is concluded that the rat vas deferens preparation constitutes a specific bioassay for endogenous opioid peptides and related compounds.

Animals↗
PubMed1977

[Adhesive otitis: 30 surgical cases (author's transl)].

Adhesive otitis accounts for 3% of all cases of chronic otitis. It is characterized by the attachment of the entire epidermal layer of the drum to the inner wall of the cavity. Three causative factors are identified: abnormal permeability of the auditory tube; absence of the fibrous layer of the tympanic membrane; a predisposing milieu. This is a very different condition from tympanosclerosis and its scleroadhesive sequelae. It can, however, be associated with cholesteatoma. An analysis of 30 cases in which surgery was performed points to the real progress brought about by the use of tympanic homografts. One problem remains: permanent aeration of the new tympanic cavity.

Adolescent↗