Showing papers by "University of Buenos Aires published in 1979"
TL;DR: According to the finding that GSSG release occurs into bile, measurements were carried out in bile samples obtained from anesthetized rats and confirmed the release of both oxidized and reduced ghrtathione from the liver of rats chronically treated with ethanol.
231 citations
TL;DR: In this article, Nifurtimox (a nitrofuran derivative) was added to trypanosoma cruzi culture (epimastigote) to induce an increase in the respiratory rate and the release of H 2 O 2 from the whole cells to the suspending medium.
130 citations
TL;DR: The results suggest a central action of both cholinergic agents attributable to an activation of muscarinic brain receptors in mice and an action of oxotremorine and physostigmine on mechanisms involved in memory storage.
Abstract: The immediate posttrial injection of oxotremorine (0.125, 0.250 and 0.500 μMol/kg i.p.) and equimolecular doses of physostigmine can facilitate the retention of a passive avoidance response in mice. Injections given 10 min after training also significantly facilitate retention, but injections given 30 or 120 min after training do not affect retention. These findings suggest an action of oxotremorine and physostigmine on mechanisms involved in memory storage. The enhanced retention produced by oxotremorine and physostigmine was blocked by pretreatment with atropine (2 μMol/kg, 20 min, i.p.) but was not affected by methylatropine (2 μMol/kg, 20min, i.p.). The retention was not modified by posttrial injection of metoxotremorine (0.250 μMol/kg i.p.) or neostigmine (0.250 μMol/kg i.p., quaternary analogs of oxotremorine and physostigmine, respectively. The results suggest a central action of both cholinergic agents attributable to an activation of muscarinic brain receptors.
106 citations
TL;DR: The present observations indicate an inhibitory effect of melatonin on the spontaneous neuronal activity of the mesencephalic reticular formation, which may contribute to the changes in the sleep-wakefulness cycle and anticonvulsant action attributed to this hormone.
64 citations
TL;DR: The Meseta Buenos Aires as discussed by the authors is an olivine basaltic unit that is associated with andesite flows of tholeiitic character and has a minimum age of 57 m.y.
Abstract: The Meseta Buenos Aires faces the triple junction between the Nazca, Antarctic, and South American plates and consists of two olivine basaltic units separated by two sedimentary units. Seventeen whole-rock K-Ar age determinations gave a minimum age of 57 m.y. (late Paleocene) for the lower unit and ages ranging from 16 to 4.4 m.y. (early Miocene to Pliocene) for the upper unit. The Friasian Land-Mammal Stage sedimentary unit underlying the upper basaltic unit is assigned to the late Oligocene-early Miocene interval, and the marine sedimentary unit underlying the Friasian deposits and overlying the lower basaltic unit is assigned to the Eocene–early Oligocene interval. The lower basaltic unit rests unconformably on a marine fossiliferous sedimentary unit of probable Late Cretaceous to early Paleocene age. The basalts of the Meseta Buenos Aires are alkaline and are associated with andesite flows of tholeiitic character. The lower unit formed while the Farallon plate was being subducted under the South American plate, and any relation between this unit and the triple junction is excluded. The origin of the upper unit could be related to perturbations in the subcrustal mantle caused by the subduction of segments of the Chile Rise. Geochemical considerations, in addition to the fact that both basaltic units formed under different tectonic settings, are consistent with the hypothesis that the origin of the alkali basalts is independent of the environment in which they are found.
52 citations
TL;DR: In this article, the 13 C NMR spectra of some tertiary and quaternary aporphine alkaloids are recorded and the signals assigned, and the substituent shielding effects together with the effects of N - and O -methylation and the twisting of the biphenyl system are analyzed and utilized in the spectral interpretation.
48 citations
TL;DR: The microsomal glucosidases which act on the oligosaccharide that contains 2 N-acetylglucosamine, 9 mannose and 1–3 glucose residues have been studied and some properties of the enzymes are described.
44 citations
TL;DR: The observations that after in vivo administration of low doses of actinomycin D there is a decrease in the RNA polymerase II with a concomitant inhibition in theRNA polymerase I activity in the isolated nuclei lend support to the proposal thatLow doses ofActinomycus D affect rRNA synthesis through inhibition of the synthesis of messenger RNAs (mRNAs) of high turnover which code for proteins required for nucleolar activity [S].
44 citations
TL;DR: Palaeomagnetic data from 101 hand samples collected in a rock sequence of about 300m of red beds and igneous rocks of the La Colina Formation (Late Palaeozoic) and Amand-Talampaya Formation (Early Triassic) exposed in north-western Argentina (30" S 67" W) are given as mentioned in this paper.
Abstract: Summary. Palaeomagnetic data from 101 hand samples collected in a rock sequence of about 300m of red beds and igneous rocks of the La Colina Formation (Late Palaeozoic) and Amand-Talampaya Formation (Early Triassic) exposed in north-western Argentina (30" S 67" W) are given. Samples were submitted to thermal, chemical and AC cleaning. After cleaning, the majority of La Colina Formation samples showed reversed polarity and yielded a palaeomagnetic pole at 49" S 343" E (ag5 = So), which is consistent with the K-Ar age (295 * 5 Myr, Late Carboniferous) of a basaltic lava flow situated in the middle of La Colina rock succession. These rocks also recorded a normal polarity event (which we haveacorrelated with the latest normal polarity event of the Debal'tseva Zone at the base of the Kiaman Magnetic Interval) and two excursions of the geomagnetic field. After treatment, the samples from the Amana-Talampaya Formation showed normal and reversed polarity and revealed frequent reversals and excursions of the geomagnetic field suggesting an Illawarra Zone age (post Kiaman, Late Tatarian-Early Scyntian and younger).
37 citations
TL;DR: It is concluded that heme oxygenase is not specific for hemin IX, and the enzyme is highly selective for the α-methine bridge, defined as the methine opposed to that flanked by the 6,7-propionic acid residues.
35 citations
TL;DR: There is experimental evidence that several of these effects are produced by different parts of the molecule, and how these active centers produce the corresponding physiological effects is still an unsolved problem.
TL;DR: A SEM study of the basal intercellular spaces of the retina in chick embryos of different developmental stages finds that, in the more advanced stages, the vitreal expansions from retinal cells are placed in rows following the same orientation as the axon bundles.
Abstract: We have made a SEM study of the basal intercellular spaces of the retina in chick embryos of different developmental stages. Since this is the environment where optic axons grow, the structural characteristics of this region might play some role in the orientation of axonal migration towards the choroid fissure. The basal region of undifferentiated retinas is formed by the vitreal expansions of neuroepithelial cells. In pre-axonal stages, the intercellular spaces between these expansions do not show any preferential orientation towards the fissure. The growth cones of ganglion cell axons appear in an apicobasal direction and turn towards the fissure immediately beneath the vitreal surface. Fasciculation is an early event during development and, in the more advanced stages, the vitreal expansions from retinal cells are placed in rows following the same orientation as the axon bundles. These observations are discussed in relationship to current hypotheses on axonal migration and orientation.
TL;DR: The results obtained, after the action of different concentrations of Triton X-100, suggest that, while nicotinic receptors are post Synaptic, the muscarinic ones are both pre- and postsynaptic.
TL;DR: The chemical shifts of the carbons of the peptide alkaloids discarine-A, discarineB, lasiodine-B, Lasiodine A,Lasiodine B,lasiodine C, Lasidine D,Lasidine E,Laside D, Lasidee E, Pandamine, Pandaminine and hymenocardine have been assigned in this paper.
TL;DR: Human polymorphonuclear leukocytes were cytotoxic to Trypanosoma cruzi epimastigotes in the presence of specific antibodies from Chagas' disease patients and sera from rabbits immunized with homogenates of T. cruziEpimastIGotes.
TL;DR: The results indicate a negative feedback between prolactin content and DNA synthesis in the rat anterior pituitary gland.
Abstract: We investigated the relationship between prolactin content and DNA replication in the anterior pituitary gland. Thymidine incorporation in pregnant rats is significantly lower than in virgin controls. This is accompanied by a decreased activity of DNA polymerase. Sulpiride administration to pregnant rats enhances thymidine incorporation to levels similar to virgin controls. The results indicate a negative feedback between prolactin content and DNA synthesis in the rat anterior pituitary gland.
TL;DR: Le fragment 6-1 du poeme de Parmenide "il est necessaire de dire and de penser qu'il y a de l'etre (ou que l'tre existe)" pose le probleme du sens predicatif ou existentiel du verbe etre, solutions qu'envisage de maniere erudite l'auteur as discussed by the authors.
Abstract: Le fragment 6-1 du poeme de Parmenide "il est necessaire de dire et de penser qu'il y a de l'etre (ou que l'etre existe)" pose le probleme du sens predicatif ou existentiel du verbe etre, solutions qu'envisage de maniere erudite l'auteur. La ligne 6.3, parle d'un eloignement de ce chemin. Dans l'ensemble integre 6.4-7.5a on trouve une description complete de l'impraticabilite d'un chemin de la recherche fonde sur les sens et l'intellect errant, et une exhortation a l'utilisation du logos revele par la deesse qui constitue le second chemin.
TL;DR: The results suggest that preincubation of the vesicles in Tris causes an increase of their permeability for Ca, or a membrane damage, and that Tris must diffuse within thevesicles to promote these effects.
01 Jan 1979
TL;DR: The Fisher's dispersion analysis test was employed and it was established that the Bucher's method working between 4 times 108 and 1 times 108 spermatozoa showed no significant variation of the results.
Abstract: The Fisher's dispersion analysis test was employed to establish the accuracy limits of spermatozoa concentrations for the evaluation of ATP content of spermatozoa. It was established that the Bucher's method working between 4 times 108 and 1 times 108 spermatozoa, showed no significant variation of the results. With less than 1 times 108 spermatozoa results are significantly different and therefore they are not reliable.
TL;DR: By purifying the crude enzyme extracts from leaves of different ages on DEAE-cellulose columns it was shown that the decrease in deaminase activity was due to a real decrease in the amount of enzyme.
Abstract: The activity of porphobilinogen deaminase was measured in young and senescent or mature leaves of pepper (Capsicum annuum), and poinsettia (Euphorbia pulcherrima). Whereas high activity was found in the crude extracts of the young leaves, almost no activity was found in the extracts of senescent or mature leaves. The decrease in deaminase activity was not due to the presence of an isolatable inhibitor. By purifying the crude enzyme extracts from leaves of different ages on DEAE-cellulose columns it was shown that the decrease in deaminase activity was due to a real decrease in the amount of enzyme. Fruiting also decreased porphobilinogen deaminase activity. Several kinetic constants of the C. annuum deaminase were determined.
TL;DR: Antigenic determinant areas were detected in bovine growth hormone fragments 6–124 and 125–149, the former being predominant, and the activity seems to be concentrated in the sequence 87–124.
Abstract: Antigenic determinant areas were detected in bovine growth hormone fragments 6--124 and 125--149, the former being predominant. Reduction and carboxymethylation of disulfide bridge 53--164 destroys the immunological reactivity of the area which is little affected by reduction and carbamoylmethylation. All the activity found in fragment 6--124 seems to be concentrated in the sequence 87--124.
Journal Article•
TL;DR: This is the first description of an association between idiopathic atrophoderma and C2 deficient state and a Family with hereditary deficiency of the second component of complement was studied.
Abstract: . A Family with hereditary deficiency of the second component of complement was studied. Three siblings were homozygous for C2 deficiency and two of them had associated skin diseases. Ono sister presented with idiopathic atrophoderma and the other had clinical and pathological manifestations of discoid lupus erythematosus. This is the first description of an association between idiopathic atrophoderma and C2 deficient state.
01 Jan 1979
TL;DR: Bovine and human growth hormone labeled with 125 I were injected into turtle Chrysemys dorbigni in order to study their distributions in tissues and suggests specific uptake of hGH or bGH by the liver and the presence in the liver of both somatogenic and lactogenic binding sites.
TL;DR: The porphobilinogen oxygenase was isolated from red cells of healthy persons and of patients with disturbances in porphyrin metabolism and was found to be heterogeneous when compared with the enzyme of other sources.
TL;DR: In this article, the expected values of certain random variables associated with a random process of manifolds in R n were computed by inserting certain general formulas of integral geometry into the definition of the moment measures of a point process.
Abstract: We compute the expected values of certain random variables associated with a random process of manifolds in R
n
by inserting certain general formulas of integral geometry into the definition of the moment measures of a point process.
TL;DR: The findings suggest that the intracellular prolactin content of the anterior pituitary gland plays a role in the regulation of DNA synthesis through a mechanism mediated by oestrogens.
Abstract: Sulpiride administration to rats releases prolactin and increases DNA replication in the anterior pituitary gland. Clomiphene prevents the stimulation of DNA synthesis produced by sulpiride, but does not affect prolactin release from the gland. These findings suggest that the intracellular prolactin content of the anterior pituitary gland plays a role in the regulation of DNA synthesis through a mechanism mediated by oestrogens.
TL;DR: A rapid, simple and economical method is described for typing monoclonal immunoglobulins, a modification of the immunofixation electrophoresis method and cellulose acetate has been used as a supporing medium.