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Augusto Arce

Bio: Augusto Arce is an academic researcher from National University of Cordoba. The author has contributed to research in topics: GABAA receptor & Receptor. The author has an hindex of 16, co-authored 28 publications receiving 684 citations.

Papers
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Journal ArticleDOI
TL;DR: Analysis of gangliosides labelled with CMP-N[(3)H]-acetylneuraminic acid showed that rigid relationships exist between the enzymes and the sialyl acceptors; the enzymes are not free to interact with all the specific substrates present in the preparation.
Abstract: Gangliosides bound to subcellular particles from rat brain were labelled by incubation of the particles (i) with CMP-N[3H]-acetylneuraminic acid and (ii) simultaneously, with CMP-N[3H]-acetylneuraminic acid and UDP-N-acetyl-[14C1]galactosamine or with CMP-N[3H]-acetylneuraminic acid and UDP-[U-14C]-galactose. Analysis of the labelled gangliosides showed that in (i), (a) the labelling was mostly in the neuraminidase-labile sialyl groups, (b) rigid relationships exist between the enzymes and the sialyl acceptors; the enzymes are not free to interact with all the specific substrates present in the preparation and (c) the precursor of the trisialoganglioside was the major disialoganglioside with a sialyl 2→8 sialyl group. In (ii), (a) precursor–product relationships between the main pools of each ganglioside apparently do not exist, (b) for the labelling of Tay–Sachs ganglioside the amount formed from hematoside was at least 2.5 times that from aminoglycolipid and (c) the major monosialoganglioside was the precursor for the major disialoganglioside with a sialyl 2→8 sialyl group.

79 citations

Journal ArticleDOI
TL;DR: Rat brain homogenate catalyzes the transfer of N -acetylneuraminic acid from cytidine-5′-monophospho- N - caches to different ganglioside derivatives, and the products of the synthesis were tentatively identified.

71 citations

Book ChapterDOI
TL;DR: The pathways of synthesis of brain gangliosides have been inferred from results of usual enzymic experiments in which all the substrates are from exogenous origen and from results in which endogenous acceptors present in subcellular membranes are labelled by using exogenous, water soluble donors.
Abstract: The pathways of synthesis of brain gangliosides have been inferred from results of usual enzymic experiments in which all the substrates are from exogenous origen and from results of experiments in which endogenous acceptors present in subcellular membranes are labelled by using exogenous, water soluble donors. For the synthesis of most gangliosides the results obtained with both methods are in agreement but in the synthesis of GDIb they are discrepant. The pathways obtained with each method are summarized in Fig. 1a and 1b. In the present communication we will deal preferentially with progress made in this field since the ganglioside conference at Strasbourg in 1973 (see ref. 12).

56 citations

Journal ArticleDOI
TL;DR: It was concluded that partial turnover of the ganglioside molecule does not occur and a model for the synthesis ofgangliosides is presented that accounts for results from previous experiments in vitro and the lack of precursor-product relationships observed in experiments in vivo.
Abstract: 1. After injection of [6-3H]glucosamine into 8-day-old rats it was found that all the major brain gangliosides and their sialyl groups were labelled at essentially the same rate, except the hematoside, which was the least labelled. In 18-day-old rats it was found that the two major gangliosides with the sialyl (2→8)-sialyl linkage, and their sialyl groups were more labelled than the hematoside, the Tay–Sachs ganglioside, the other two major gangliosides and their respective sialyl groups. 2. No difference was found in any of the cases studied between the specific radioactivities of the neuraminidase-resistant and -labile sialyl groups belonging to the same ganglioside. The same was found for the specific radioactivities of the galactosyl groups proximal and distal to the ceramide moiety of total brain gangliosides from rats injected with [U-14C]glucose. From this it was concluded that partial turnover of the ganglioside molecule does not occur. 3. A model for the synthesis of gangliosides is presented that accounts for results from previous experiments in vitro and the lack of precursor–product relationships observed in experiments in vivo.

53 citations

Journal ArticleDOI
TL;DR: It was concluded that recently synthesized polysialogangliosides (completed in vitro) are in the membranes in a position less accessible to neuraminidase than are those synthesized earlier which were present in the membrane at the start of the labelling experiment.
Abstract: 1. Treatment of rat brain microsomal membranes with a neuraminidase preparation from Clostridium perfringens resulted in an almost complete conversion of polysialogangliosides into monosialogangliosides. 2. Neuraminidase treatment of the membranes did not increase the incorporation of N-[3H]acetylneuraminic acid from CMP-N-[3H]acetylneuraminic acid into the gangliosidic fraction, indicating that a monosialoganglioside is an acceptor of N-acetylneuraminic acid in these membranes only if, in addition to having the right chemical structure, it is in a proper position, probably in relation to the endogenous sialyltransferases. 3. These experiments also indicated that no independent turnover of the neuraminidase-labile N-acetylneuraminyl groups of gangliosides occurred in vitro. 4. N-[3H]Acetylneuraminic acid from endogenous polysialogangliosides labelled in vitro was released by neuraminidase at a slower rate than N-acetylneuraminic acid from unlabelled gangliosides of the same membranes. From this it was concluded that recently synthesized polysialogangliosides (completed in vitro) are in the membranes in a position less accessible to neuraminidase than are those synthesized earlier which were present in the membranes at the start of the labelling experiment.

49 citations


Cited by
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Journal ArticleDOI
TL;DR: Compounds that have a different spectrum of therapeutic efficacy in anxiety disorders such as panic attacks, generalized anxiety disorder or obsessive-compulsive disorder were poorly effective as anxiolytics in the open field test, suggesting that this paradigm may not model features of anxiety disorders.

2,665 citations

Journal ArticleDOI
TL;DR: This review attempts to establish the level of repeatability and validity found for fear tests used on cattle, pigs, sheep and goats, poultry and horses, and focuses on the three most common types of fear tests: the arena test, the novel object test, and the restraint test.

755 citations

Journal ArticleDOI
26 Nov 1976-Science
TL;DR: Observations are attempted to unify observations and provide a reasonable interpretation of the role of gangliosides in mediating cell surface phenomena to predict that analyogous phenomena involving gangliosisides will be discovered in brain.
Abstract: Gangliosides are unique acidic glycolipids that are selectively concentrated in the plasma membrane of cells. Surface labeling studies have demonstrated that at least a portion of the oligosaccharde chain of gangliosides extends beyond the hydrophe) is imbedded in the membrane bilayer. It is becoming increasingly apparent that gangliosides participate in the internalization of environmental signals elicited by cholera toxin and glycoprotein hormones such as thyrotropic hormone and chorionic gonadotropin as well as other substances such as interferon and possibly serotonin. The mechanism by which cholera toxin binds to a specific ganglioside receptor on the celraction of trophic agents with gangliosides. We would predict that analyogous phenomena involving gangliosides will be discovered in brain. The biosynthesis of gangliosides proceeds by the ordered sequential addition of sugars to the lipid moiety. These reactions are catalyzed by a cluster of membrane-bound glycosyltransferases. Any alteration in the activity or specificity of one of these enzymes will result in a dramatic change in the ganglioside pattern of an afflicted cell or organ. The drastic consequences that accompany abnormalities of ganglioside synthesis have been documented in a heritable metabolic disorder in vivo and in tumorigenic transformation of cells in vitro. In this article, we have attempted to unify these observations and to provide a reasonable interpretation of the role of gangliosides in mediating cell surface phenomena.

719 citations

Journal ArticleDOI
TL;DR: The period of discovery of new lipids in the nervous system appears to be over and all the major lipid components have been discovered and a great deal is now known about their structure and metabolism.

694 citations

Journal Article
TL;DR: Benzodiazepines (BZs)2 are used clinically as muscle relaxants, anticonvulsants, anxiolytics, and sedative-hypnotics.
Abstract: Benzodiazepines (BZs)2 are used clinically as muscle relaxants, anticonvulsants, anxiolytics, and sedative-hypnotics. These effects are mediated primarily via the central BZ receptors (CBRs) located in the central nervous system (CNS;[Braestrup and Squires, 1977][1]; [Mohler and Okada, 1977][2]; [

505 citations