Showing papers by "University of Buenos Aires published in 1969"
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TL;DR: The evolution differed in each case, but, in those cases in which the tumor was not widely resected, it tended to recur and be found more often in the female subject and in the lower jaw.
162 citations
TL;DR: In the convulsant rat, ultra-structural alterations of some nerve endings of the cerebral cortex were observed and altered nerve endings were preferentially found in the GAD-rich (nonaminergic) fraction of isolated nerve endings.
86 citations
TL;DR: The finding that bovine growth hormone was as effective as triiodothyronine raises the question of whether the effects of early thyroid dysfunction on cerebral development reflect a direct action of thyroid hormone on this process or whether they are indirectly mediated.
76 citations
TL;DR: Several experiments with thin layer and column chromatography suggest that in the organic phase the [14C]5‐HT is not bound to the lipids but to a special proteolipid, different from that found in myelin and has similar chromatographic properties to that previously observed in the proteolIPid.
Abstract: —In vitro binding experiments with 5-hydroxy[14C]tryptamine (3.3 × 10−6 M) were carried out on subcellular fractions of the cat brain. The highest specific activity was observed in some fractions of nerve-ending membranes isolated from the hypothalamus, basal ganglia, and gray areas of the mesencephalon. The specificity of this high affinity binding was demonstrated by competition with reserpine, butanolamide of lysergic acid, and desmethylimipramine. With butanol-water extraction the [14C]5-HT was found in the butanol while the gangliosides were separated in the water phase. Several experiments with thin layer and column chromatography suggest that in the organic phase the [14C]5-HT is not bound to the lipids but to a special proteolipid. This proteolipid is different from that found in myelin and has similar chromatographic properties to that previously observed in the proteolipid which binds d-[14C]tubocurarine in nerve-ending membranes of the cerebral cortex.
70 citations
TL;DR: The ultrastructural and histochemical changes of the sex chromosomes (sex vesicle) during meiosis in the male mouse have been sequentially studied.
70 citations
67 citations
TL;DR: Different patterns of elution for grey and white matter extracts were found and the implications are discussed in relation to the chemical and physicochemical characteristics of the different proteolipids and to the receptor properties shown by some of them in grey matter.
60 citations
50 citations
01 Jan 1969
TL;DR: Chemical synapses are by far the more common and are the only ones that will be considered here from the point of view of their structural and biochemical organization.
Abstract: The synaptic region may be defined as the site of contact between two excitable cells having a specific structural, biochemical, and functional differentiation for the transmission of nerve impulses. As suggested by Du Bois Raymond in 1877, synaptic transmission may be either chemical or electrical, and both mechanisms have been found to occur in the peripheral and central nervous systems. However, chemical synapses are by far the more common and are the only ones that will be considered here from the point of view of their structural and biochemical organization.
50 citations
TL;DR: Experiments confirmed that the receptor properties for d-tubocurarine may be in a special type of proteolipid present in the nerve-ending membrane, probably at the junctional complex and in relation to previous attempts to isolate a cholinergic receptor.
Abstract: The binding capacity of isolated acetylcholinesterase-rich nerve-ending membranes of the cat cerebral cortex for dimethyl-14C-d-tubocurarine (1.5 × 10−6 M) was studied with an in vitro technique. After treatment of the membranes with organic solvents, most of the radioactivity was found in the extract and bound either to the lipids or proteolipids, but not to the gangliosides.
Comparing the binding capacity per milligram of proteolipid protein of the M1 1.0 nerve-ending fraction with that of myelin, there was a tenfold increase in specific activity in the former. This layer cromatography of a lipid extract, previously passed through Sephadex G 25 fine, showed that the radioactivity remained at the point of origin together with the proteolipids. The use of a special technique with Sephadex LH20 demonstrated that the bound dimethyl-14C-d-tubocurarine was eluted together with a protein peak which had no cholesterol and negligible amounts of phospholipids.
Experiments using precipitation with ether of the proteolipid protein and passage through the Sephadex LH20 column gave similar results and confirmed that the receptor properties for d-tubocurarine may be in a special type of proteolipid present in the nerve-ending membrane, probably at the junctional complex. These results are discussed in relation to previous attempts, reported in the literature, to isolate a cholinergic receptor.
50 citations
31 Dec 1969
TL;DR: Pineal glands of normal adult mice, 7 to 42 days after bilateral superior cervical gangliectomy and 5 and 16 hours after one dose of reserpine were studied under the electron microscope, finding that the architecture of the gland is basically similar to that of other mammalian pineal glands previously studied.
Abstract: Pineal glands of normal adult mice, 7 to 42 days after bilateral superior cervical gangliectomy and 5 and 16 hours after one dose of reserpine (10 mg/kg) were studied under the electron microscope. The architecture of the gland is basically similar to that of other mammalian pineal glands previously studied. Mouse pinealocytes are polymorphic cells with perivascular and intercellular processes. Its most prominent feature is the presence of abundant granulated vesicles with a mean diameter of 1100 A and a dense core of about 800 A intermingled with clear vesicles of similar size distributed throughout the cytoplasm and more concentrated in perivascular and intercellular processes. These processes were seen in continuity with the perykaryon and remained after bilateral superior cervical gangliectomy. Processes containing the plurivesicular component of adrenergic nerves situated in perivascular and intercellular spaces disappeared after bilateral superior cervical gangliectomy. Reserpine depleted small granulated vesicles of nerves but the larger ones of perikaryon and polar processes remained almost unchanged. The histochemical technique of Wood was positive for catechol- and indolamines in the nerves. The reaction was negative in the perikaryon and polar processes. The significance of these findings is discussed.
TL;DR: The correlation between morphological and biochemical data suggests that both catechol and indolamines are stored in granulated vesicles in the pineal nerves of the rat.
TL;DR: Testicular biopsies of 6 adult patients operated for chromophobe adenoma have been studied before and after treatment with HCG, HMG, and HMG withHCG to estimate the variations in the relative number of germinal and Leydig cell populations.
Abstract: Testicular biopsies of 6 adult patients operated for chromophobe adenoma have been studied before and after treatment with HCG, HMG, and HMG with HCG. Control biopsies were obtained at different intervals of time in each case, ranging from 6 months to 10 yr after operation. Based on the extent of the regression of germinal epithelium, tubular wall and interstitial cells, the patients were classified in 2 groups, each one comprising 3 patients. Group I showed germinal cells up to spermatocyte level accompanied by moderate peritubular hyalinization and partial atrophy of Leydig cells. Group II only showed spermatogonial and Sertoli cells, accompanied by intense peritubular hyalinization and almost complete atrophy of Leydig cells. In order to estimate the variations in the relative number of germinal and Leydig cell populations before and after treatment, a cell count was applied to histological sections. The 3 patients of the 2 groups received treatment during 3 months with one of the following ho...
TL;DR: Glycogen content in the rat testis was chemically and histochemically studied during maturation of the gonad, and an abrupt drop in 10- and 15-day-old rats was observed.
Abstract: Glycogen content in the rat testis was chemically and histochemically studied during maturation of the gonad. Higher values in the immediate post-natal period, and an abrupt drop in 10- and 15-day-old rats was observed. From 20 days onward, there was a progressive decrease, reaching the lowest values in adultanimals. Histochemically, glycogen was mainly present in the germinal cells, i.e., in gonocytes from 5 to 15 days old, and in primary spermatocytes from 15 to 20 days. A weaker reaction was noticed in spermatogonia and Sertoli cells of adult animals. (Endocrinology 85: 607, 1969)
TL;DR: In this paper, the authors use the positions of the magnetic south pole in the Triassic determined by palaeomagnetic studies of African and South American rocks to reconstruct the drifting apart of Africa and South America in the Permian.
Abstract: ON the basis of the positions of the magnetic south pole in the Triassic determined by palaeomagnetic studies of African and South American rocks, Creer1 has argued that the drifting apart of Africa and South America began in the Permian. Briefly, if South America and Africa are placed in such a position that their Palaeozoic polar wandering curves coincide, there is obtained a reconstruction very similar to that suggested by the shapes of the coastlines, and the earliest palaeopoles which do not coincide are those of the Triassic. In this argument, the Triassic palaeopole for South America was computed from a study of the lavas of the Serra Geral formation, in the southern part of Brazil. Unfortunately, a radiometric study2 of forty-one samples of basalt and dacite has shown that the principal phase of this igneous cycle is of Middle Cretaceous age, about 115–125 m.y.
TL;DR: The binding capacity of subcellular fractions, from the cat basal ganglia and brain stem, was studied using respectively α- and β-adrenergic blocking agents 14C-dibenamine and14C-propanolol to suggest that it may be a special proteolipid present in the nerve-ending membranes.
TL;DR: In this article, D'Appoloia, D'Apolonia, Elio D'APPOLONIA, and RICHARD F. BRISSETTE discussed the effect of over-buried pressure on the relative density of SANDs.
Abstract: WAYS TO MODIFY THE TERZAGHI AND PECK METHOD FOR ESTIMATING THE SETTLEMENT OF SPREAD FOOTINGS FOUNDED ON SANDS ARE EXAMINED. THE AUTHORS INCLUDE THE EVALUATION OF THE RELATIVE DENSITY OF SAND FOUNDATIONS BY THE STANDARD SPLIT-BARREL PENETRATION TEST UTILIZING THE EFFECT OF OVERBURDEN PRESSURES. THE WRITERS' PREFER TO REGARD THIS IN TERMS OF INTERPRETATION OF THE RELATIVE DENSITY OF SANDS UNDER VARIOUS OVERBURDEN PRESSURES FROM PENETRATION TEST DATA, RATHER THAN A CORRECTION AS EXPRESSED BY THE AUTHORS AND DISCUSSERS. EXPERIENCE ON BUREAU OF RECLAMATION PROJECTS DURING THE LAST 15 YEARS HAVE PROVIDED CONFIDENCE IN THE APPLICABILITY OF THE PROCEDURE. PENETRATION TEST RESULTS MUST BE LOOKED AT FROM THE STANDPOINT OF AVERAGE VALUES AND RANGE OF VALUES. THE WRITER FEELS THAT A CORRELATION WHICH IS CLOSE TO AVERAGE TRENDS OF PENETRATION RESISTANCE AND RELATIVE DENSITY IS MOST USEFUL. CHANGES OF OVERBURDEN PRESSURE WITH RESPECT TO DEPTH IS A NECESSARY CONSIDERATION. HOLTZ AND GIBBS CONCLUDE THAT A GENERAL CORRELATION SHOULD BE AN AVERAGE REPRESENTATION FOR A BROAD VARIETY OF USES. PECK AND BAZARAA DISCUSS THE PENETRATION TEST METHODS. THEY DISCUSS THE CORRECTION OF N VALUES FOR THE EFFECT OF OVERBURDEN PRESSURES USED BY THE AUTHORS. THEY CRITICIZE THE HOLTZ AND GIBBS CORRECTION AS BEING UNREALISTIC AND INTRODUCING AN INHERRENT INCONSISTENCY INTO THE PROCEDURES. A METHOD OF IMPROVING THE GIBBS AND HOLTZ CORRECTION IS INTRODUCED. THE WRITER SUGGESTS THAT THE N VALUES SHOULD BE CORRECTED FOR THE EFFECT OF OVERBURDEN PRESSURE, PREFERABLY BY BAZARAA'S MODIFICATION OF THE GIBBS AND HOLTZ PROCEDURES. THE CORRECTED N VALUES SHOULD THAN BE INSERTED INTO THE TERZAGHI-PECK CHART TO DETERMINE THE SETTLEMENT BY THE STANDARD SPLIT-BARREL PENETRATION TEST. BOLOGNESI DISCUSSES SETTLEMENTS PREDICTIONS FROM PLATE LOAD TESTS AND THE INFLUENCE OF THE WATER TABLE ON THE SETTLEMENT OF FOUNDA- TIONS. A FIGURE IS PRESENTED WHICH SHOWS ALL THE POSSIBILITIES AND LIMITATIONS OF THE PROPOSAL THAT, ON FIRST LOADING, THE TANGENT MODULUS OF DEFORMATION OF SANDS IS A FUNCTION OF THE STRESS CONDITIONS. THE ANALYSIS PRESENTED SHOWS THAT THE MOST IMPORTANT FACTOR TO BE TAKEN INTO CONSIDERATION WHILE EXTRAPOLATING SETTLEMENTS FROM A STANDARD SIZE PLATE TO THE SETTLEMENT OF A PROTOTYPE FOOTING IS THE PRECONSOLIDATION PRESSURE, OR PRECONSOLIDATION-LIKE EFFECTS. REFERENCES: SETTLEMENT OF SPREAD FOOTINGS ON SAND, DAVID J. D'APPOLONIA, ELIO D'APPOLONIA, AND RICHARD F. BRISSETTE, ASCE PROC. PAPER 5959, MAY 1968.
TL;DR: When South America, Africa and Australia are placed in their pre-drift relative positions, a common polar wandering curve can be constructed through their upper Carboniferous and Lower and Upper Permian poles.
TL;DR: Although the findings are still preliminary the dose-response curves obtained show a sigmoid shape characteristic of a cooperative interaction, which is reminiscent of similar phenomena observed in excitable membranes 151.
TL;DR: Treatment of prepubertal male rats under constant illumination with 100, 300 and 500 μg of melatonin resulted in a decrease in the weight of the anterior pituitary and seminal vesicles, whereas only the 500 μg dose significantly affected the testicular weight.
Abstract: Treatment of prepubertal male rats under constant illumination with 100, 300 and 500 μg of melatonin resulted in a decrease in the weight of the anterior pituitary and seminal vesicles, whereas only the 500 μg dose significantly affected the testicular weight. No changes took place in the gonadotrophic levels of FSH or LH in the pituitary gland. Two hypotheses are suggested to explain this apparent discrepancy. (Endocrinology 84: 937, 1969)
TL;DR: The finding points to the histochemical demonstration of an unidentified component (s) of the retina which shows a striking specificity of localization and which is made evident when zinc iodide is used in the Champy-Maillet mixture.
Abstract: The osmium tetroxide-zinc iodide fixative of Champy-Maillet has been used to study the rat's retina at the electron microscope level. Electron opaque deposits were observed all along the photoreceptor cells and concentrated in the outer segments of rods and cones and in the nerve endings. In the outer segments that deposits are located in the inter and intra disk spaces as well as between the disk and outer membranes. In the outer plexiform layer reactive sites include synaptic vesicles and mitochondria; other minor reactive sites are described in the inner segment and inner plexiform layer. Electron opaque deposits were not seen if potassium iodide substitutes zinc iodide in the fixative. However, if osmium tetroxide-potassium iodide fixed retinae are immersed in osmium tetroxide-zinc iodide the characteristic electron-dense material is evidenced at those same sites. The effect of other several fixatives were studied with a similar “double” fixation procedure. Our finding points to the histochemical demonstration of an unidentified component (s) of the retina which shows a striking specificity of localization and which is made evident when zinc iodide is used in the Champy-Maillet mixture.
TL;DR: The effect of high concentrations of Mg(2+) (or Mn(2+)) on the kinetics of yeast pyruvate carboxylase can be explained as a deinhibition with respect to ATP(4-), instead of a direct enzyme activation.
Abstract: 1. Pyruvate carboxylase from baker's yeast acts with either MgATP2− or MnATP2− as substrate. The optimum pH for the enzyme reaction is 8·0 with MgATP2− and 7·0 with MnATP2−. 2. When the reaction velocity is plotted against MgATP2− (or MnATP2−) concentration slightly sigmoid curves are obtained, either in the presence or in the absence of acetyl-CoA (an allosteric activator). In the presence of excess of free Mg2+ (or Mn2+) the curves turn into hyperbolae, whereas in the presence of excess of free ATP4− the apparent sigmoidicity of the curves increases. 3. The sigmoidicity of the plots of v against MgATP2− (or MnATP2−) concentration can be explained by the inhibitory effect of free ATP4−, the concentration of which, in the experimental conditions employed, is significant and varies according to the total concentration of the ATP–magnesium chloride (or ATP–manganese chloride) mixture. Free ATP4− behaves as a negative modifier of yeast pyruvate carboxylase. 4. The effect of high concentrations of Mg2+ (or Mn2+) on the kinetics of yeast pyruvate carboxylase can be explained as a deinhibition with respect to ATP4−, instead of a direct enzyme activation. 5. At pH6·5 manganese chloride is more effective than magnesium chloride as enzyme activator even in the presence of a great excess (16-fold) of the latter. This is consistent with a significant contribution of the MnATP2− complex to the activity of yeast pyruvate carboxylase, in medium conditions resembling those existing inside the yeast cell (pH6·25–6·75; 12mm-magnesium chloride and 0·75mm-manganese chloride). 6. The physiological significance of the enzyme inhibition by free ATP4− is doubtful since the Mg2+ and Mn2+ concentrations reported to exist inside the yeast cell are sufficient to decrease ATP4− concentrations to ineffective values.
TL;DR: The hypertrophy of the retrolingual gland following incisor amputations was prevented only by denervation of both the sympathetic and parasympathetic nerves, it being transmitted by both nerves.
TL;DR: A histometric analysis of bone density was made in the interradicular bone of rats fed either a powdered protein free diet, pair-fed with an isocaloric 27 % casein diet or fed control diets, ad libitum, of either soft or hard consistencies, and a marked osteoporosis was found.
Abstract: A histometric analysis of bone density was made in the interradicular bone of rats fed either a powdered protein free diet, pair-fed with an isocaloric 27 % casein diet or fed control diets, ad libitum, of either soft or hard consistencies. A marked osteoporosis was found in the two nutritionally restricted groups. The pair fed animals showed a greater osteoporosis than the protein deficient animals. These results were statistically significant (p = 0.001).
TL;DR: In this article, a complete analysis of the high resolution proton magnetic resonance spectra of monosubstituted benzaldehydes has been performed as an ABCDE spin system.
Abstract: A complete analysis of the high resolution proton magnetic resonance spectra of monosubstituted benzaldehydes has been performed as an ABCDE spin system. The chemical shifts and the coupling constants are determined in six compounds with great accuracy. By using the additivity rule the calculated proton coupling constants of benzene are (in Hertz):