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J Seguin

Publications and source records attributed to J Seguin.

50 records · Page 3Linked to original sources
PubMed1986

Influence of Ca2+e on 5-HT2- and alpha 1-induced arterial contraction and phosphoinositide metabolism.

Serotonin and phenylephrine were found to induce contractile responses and inositol phosphate (IP) formation in isolated rat tail artery. Both processes displayed similar concentration dependence in the presence of 2.5 mM external calcium (Ca2+e) and both were respectively inhibited by either ketanserine or prazosin, depending on the agonist used. In the absence of Ca2+e the amines no longer produced a contractile effect. In addition, lack of Ca2+ caused a shift to the right in the dose-response curve for phenylephrine-induced IP formation whereas serotonin-induced IP formation was not affected by changes in Ca2+e. The results suggest that alpha 1- and 5-HT2-induced contractions are quantitatively related to phosphatidylinositol metabolism. Contraction, but not IP formation requires the presence of Ca2+e. Different effects of Ca2+e on phenylephrine- and serotonin-induced IP formation could be related to a differential Ca2+ effect on binding of alpha 1- or 5-HT2 agonists.

Animals↗
PubMed1986

The cellular basis of salivary immunity in the mouse: incidence and distribution of B cells, T cells and macrophages in single-cell suspensions of the major salivary glands.

A multiparametric analysis of the resident immune populations in the parotid, submandibular and sublingual salivary glands was done in single-cell suspensions. The incidence of T and B cells and of macrophages was assessed using phenotypic markers in immunofluorescent staining and a functional assay was used to enumerate immunoglobulin (Ig)-secreting cells. Characteristic frequencies and isotype distributions of cytoplasmic Ig+ B cells and surface Ig+ B lymphocytes were found in the three types of glands. Even though IgA was always found to be the predominant isotype in individual salivary secretions (90-93%) this was not directly correlated by an absolute predominance of IgA-secreting cells in the glands (45-65%). Significant percentages of T cells (Thy-1+ and Lyt-1+ cells: 3-4%) and macrophages (Mac 1+ and esterase-positive cells: 3-10%) were also recovered in our suspensions. It is therefore concluded that the murine salivary glands contain both effector and regulatory cells required for the development and expression of salivary immunity.

Animals↗
PubMed1986

The oral immune system: dynamics of salivary immunoglobulin production in the inbred mouse.

In the oral cavity, salivary immunoglobulins (Igs) are the principal mediators of specific immunity. Using carbachol to stimulate saliva flow, we investigated, in a kinetic study, individual variations in salivary Ig concentrations in 23 adult BALB/c mice using an enzyme-linked immunosorbant assay (ELISA). It appeared that salivary Ig concentrations are highly variable in individual mice (IgA: 3-81 micrograms/mL; IgG: 0-2.9 micrograms/mL; IgM: 0.002-0.14 microgram/mL). In individual mice stimulated at different times over a 3 week period there are considerable variations both in salivary Ig concentrations and in their respective ratio. Broad variations were also found in the levels of specific IgA and IgG antibodies to three indigenous oral murine bacteria. Present data thus indicate that among genetically identical mice of the same age and sex, sharing identical diet, there is considerable heterogeneity in salivary Igs. As this heterogeneity was mimicked at the cellular level in major and minor salivary gland-associated B-cells, it appears that antibody dynamics in the oral cavity could reflect the adaptive capacity of the oral immune system to local antigenic challenge.

Animals↗
PubMed1983

[Surgical treatment of acute necrotizing hemorrhagic pancreatitis. Analysis and prospective deductions on 58 cases].

Three degrees of severity could be recognized in 58 patients operated upon for severe acute hemorrhagic pancreatitis, based on results of intensive care, particularly anti-shock therapy, wide peritoneal lavage, and possible need for endoscopic relief of sphincter of Oddi obstruction due to a stone. The principal parameters evaluated were clinical and biological features and the course of the affection. As a result of these data, 44 pancreatic resections of variable extension and 14 excisions of necrotic tissues were performed. Results of these two types of operations, as well as the dominant causes of postoperative and secondary deaths, are analyzed in detail. The indications for surgery are discussed, together with the tactical methods to be applied as a function of the general condition and the detailed study of the pancreas and the state of the adjacent organs. Particular importance should be attached to the presence of respiratory insufficiency. The possible need for routine biliary external drainage is discussed, and the major role played by parenteral nutrition, which should be initiated as early as possible, is emphasized. These findings suggest that two fundamental principles should guide surgery of acute hemorrhagic pancreatitis: the need for surgery in selected cases, though over-aggressive operations should be avoided, and, more particularly, the concept, to be shared of the need for repeated operations, enabling avoidance of excessive procedures during initial surgery.

Acute Disease↗
PubMedDate not supplied

Neutral postgrafted colloidal particles for gene delivery.

Surface modification of cationic lipoplexes has been carried out by means of a postgrafting reaction. The original lipoplexes described comprise a cationic lipid, a neutral lipid, poly(ethylene glycol)-cholesterol (with or without a targeting ligand) and DNA. Modifying their surface via a chemical, postgrafting reaction did not alter their size (approximately 100 nm) nor their ability to compact DNA, but did give a reduced zeta potential (approximately 0 mV) to afford surface neutral particles. With the modified lipoplexes nonspecific NIH3T3 cell surface binding in vitro was inhibited. Intravenous injection of the neutralized lipoplexes in mice showed decreased accumulation of the particles in the lung as compared to PEGylated cationic lipoplexes. Tumor targeting was also achieved in vivo by the addition of an RGD-PEG-Cholesterol as a lipid-ligand in the postgrafted lipoplex formulation.

Acetates↗