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E Rivas

Publications and source records attributed to E Rivas.

48 records · Page 3Linked to original sources
PubMed1971

Conductance changes produced by acetylcholine in lipidic membranes containing a proteolipid from Electrophorus.

Ultrathin lipidic membranes containing one ten-thousandth of a special proteolipid from electric organ of Electrophorus reacted to the addition of acetylcholine by a rapid and transient increase in conductance. Such a change was not induced by choline and is greatly reduced by a previous application of d-tubocurarine. These properties, resembling those from chemically excitable membranes, were not observed with another proteolipid from the same tissue.

Acetylcholine↗
PubMedDate not supplied

Modulatory effects of phosphatidylserine on the binding of muscarinic cholinergic receptor ligands. Studies in vitro and in vivo.

The modulation of the binding of muscarinic cholinergic receptor ligands by phosphatidylserine purified from bovine cerebral cortex (BC-PS) was examined in vitro and in vivo. The enrichment of bovine cerebral cortical synaptosomal membranes with BC-PS, using a fusion technique, produced a concentration-dependent decrease in the affinity (increase in Kd) of [3H]quinuclidinyl benzylate (3H-QNB) specific binding to muscarinic acetylcholine receptors (mAChR), without changes in their maximal number (Bmax). Similar results were observed when [3H]oxotremorine (3H-OXO) was used to label a high affinity subpopulation of mAChR. On the other hand, preincubation of BC-PS liposomes with synaptosomal membranes in a nonoptimum fusion condition (at pH 7.4) did not alter the binding properties of both radioligands. Fusion experiments using a pure phosphatidylserine preparation from spinal cord revealed a similar decrement in the affinity of 3H-QNB specific binding. Five day's intraperitoneal (i.p.) administration of 15 mg/kg of BC-PS liposomes in rats increased the maximal number of cerebral cortical binding sites for 3H-OXO. Scatchard analysis revealed no changes in the apparent dissociation constant. This modification is selective in relation to the neural structure studied. Thus, BC-PS treatment did not modify 3H-OXO binding in the hippocampal formation and cerebellum. In contrast, parallel experiments using the muscarinic antagonist 3H-QNB showed no alteration in the binding properties of mAChR. Five day's i.p. administration of 15 mg/kg/d of phosphatidylcholine from bovine cerebral cortex (BC-PC) liposomes produced quite similar results to those obtained with BC-PS. These results indicate that mAChR are under the modulatory action of phosphatidylserine (PS) and phosphatidylcholine (PC), and suggest that this endogenous phospholipids may play a regulatory role on the mAChR. The possible implications of these findings on the effects of PC or PS treatment in neurological disorders involving a decrease in central cholinergic functions are discussed.

Animals↗
PubMedDate not supplied

[Child health care program in Mexico. Evaluation of the quality of the integrated health care given in training centers].

OBJECTIVE: To assess the quality of the integral care of children under five years old (AIMCA) at three first level care units, that without additional resources, were selected by the Child Health Care Program (PASN) to function as statewide training centers. MATERIAL AND METHODS: Using matching list, structure, validated by a consensus of experts and a pilot test, six components of the AIMCA were assessed. The study included children under five years old outpatient clinic, during a period of a week: on the average 30 at each unit. RESULTS: Although there were differences between each health unit, in a high number of cases, the score given to each component of the AIMCA was optimum or satisfactory. The most relevant deficiencies were those related to the mother's training. The assessment allowed for correcting deficiencies in the AIMCA and others related with the organization of Training Centers. CONCLUSIONS: It is possible to have an AIMCA of good quality, at first level units without additional resources. We propose that the mother's training be given mainly by a nurse, especially in children with factors of poor prognosis. The methodology used can be employed to evaluate the AIMCA periodically at training centers.

Child Health Services↗