Showing papers by "University of Buenos Aires published in 1978"
TL;DR: Results are compatible with the idea that the Ca2+-ATPase from human red cell membranes has two classes of site for ATP binding, both of which are occupied when the enzyme catalyzes the hydrolysis of ATP at maximum rate.
108 citations
TL;DR: Angiotensin II released serotonin from neuron terminals and accelerated synthesis of the serotonin, and this increase in synthesis depended on the activation of tryptophan hydroxylase, which represents a subtle regulation of the open-loop serotonin system.
Abstract: Angiotensin II released serotonin from neuron terminals and accelerated synthesis of the serotonin. This increase in synthesis depended on the activation of tryptophan hydroxylase. A biphasic effect was observed: at high doses the stimulatory effect depended on conversion of angiotensin II to angiotensin III. At low doses an inhibitory effect was found, possible dependent on an angiotensin II metabolite. These actions represent a subtle regulation of the open-loop serotonin system.
76 citations
TL;DR: It is suggested that the whorl configuration caused the high rate of protein and PRL synthesis as well as the changes in RNA metabolism displayed by the tumors.
Abstract: The hormone function, the metabolism of nucleic acids, and the ultrastructure of estrogen-induced pituitary tumors and of normal glands were examined in male F344 rats. The tumors had a high capacity for prolactin (PRL) synthesis, and the plasma levels of PRL were elevated 65-fold to 100-fold in the tumor-bearing animals. Uridine uptake and phosphorylation to nucleotides, as well as uridine incorporation into total RNA, were similar in tumors and normal glands, whereas [3H]thymidine incorporation into DNA was double in the former group as compared to the latter. After a [3H]uridine pulse, labeled RNA turnover was different in tumors and normal glands. Electron microscopy of the tumors revealed hypertrophy, degranulation, and hyperplasia of cells producing PRL with proliferation of their ergastoplasm in whorls. Other pituitary cell types were reduced in number. It is suggested that the whorl configuration caused the high rate of protein and PRL synthesis as well as the changes in RNA metabolism displayed by the tumors.
67 citations
TL;DR: The results are consistent with the idea that combination of ATP at a non-catalytic site is needed for rapid dephosphorylation of the Ca2+-ATPase and suggest that the role of Mg2+ on deph phosphate conversion is to convert the phosphoenzyme into a form that reacts rapidly with water.
60 citations
TL;DR: The data suggest that hGH binds to both somatotropic and lactogenic sites in the liver of normal rats, and in hypophysectomized animals, only the somatogenic binding sites could be detected.
Abstract: The specific uptake by rat liver of human (hGH) and bovine (bGH) GHs labeled with 125I was studied by an in vivo procedure. A significant reduction of the uptake was observed when labeled hormones were injected together with different amounts of the corresponding native GH. This reduction was dose dependent, and the concentration of native hormone that prevents 50% of the liver uptake of the labeled hormone was close to 12 microgram/100 g BW. In normal rats, only native hGH or bGH significantly decreased the liver uptake of [125I]iodo-bGH, while bovine PRL (oPRL) or heat-denatured bGH were inactive. The highest inhibition of the uptake of [125I]iodo-hGH by rat liver was obtained when this labeled hormone was injected either together with hGH or with bGH plus oPRL while partial displacement was observed with bGH or oPRL. These data suggest that hGH binds to both somatotropic and lactogenic sites in the liver of normal rats. In hypophysectomized animals, only the somatogenic binding sites could be detected.
43 citations
TL;DR: O2− production is involved in the toxic action of naphthoquinones against Trypanosoma cruzi as is inferred from the correlation between quinone effect upon growth and the rate of O2− release from quin one-treated epimastigotes.
41 citations
TL;DR: β-Lapachone markedly increased the generation of superoxide anions and hydrogen peroxide by subcellular membranes of Bacillus subtilis and Bacillus stearothermophilus.
Abstract: beta-Lapachone markedly increased the generation of superoxide anions and hydrogen peroxide by subcellular membranes of Bacillus subtilis and Bacillus stearothermophilus. Peroxide generation by beta-lapachone was parallel to the inhibition of growth in both microorganisms.
40 citations
TL;DR: In this paper, Norepinephrine added in vitro to nerve ending membranes from rat cerebral cortex stimulates the activity of (Na+, K+) adenosinetriphosphatase (ATPase) only in the presence of the soluble brain fraction.
Abstract: Norepinephrine added in vitro to nerve ending membranes from rat cerebral cortex stimulates the activity of (Na+, K+) adenosinetriphosphatase (ATPase) only in the presence of the soluble brain fraction. In its absence norepinephrine inhibits the enzyme. (Mg2+)ATPase also showed stimulation by norepinephrine in the presence of the soluble fraction, but of lesser magnitude. The activation of (Na+, K+)ATPase by norepinephrine is not reproduced by cyclic AMP and is not antagonized by either α- or β-adrenergic blocking agents. These results suggest that the stimulation caused by norepinephrine is a direct effect on the enzyme and is not mediated by cyclic AMP or adrenergic receptors.
32 citations
TL;DR: The role of the alternate oxidase in plants is poorly understood, but has been found to be associated with thermogenesis 133, and suggested to be important in plant productivity, seed germination and fruit ripening, which underlines the need for more basic knowledge of this respiratory activity.
31 citations
TL;DR: Dyskinetoplasty occurred after inhibition of electron transfer by antimycin and cyanide, though to a much more significant extent, thus confirming the functional association of electron transport at the mitochondrial cytochrome system of T. cruzi and the enzymatic reactions of the tricarboxylic acid cycle.
29 citations
TL;DR: The intrinsic viscosity of hyaluronic acid in synovial fluid decreases significatively in mild and severe arthritis (24% and 37% respectively).
Abstract: The intrinsic viscosity of hyaluronic acid in synovial fluid decreases significatively in mild and severe arthritis (24% and 37% respectively). Variation in hyaluronic acid concentration parallels the above results. Chondroitin-6-sulfate can be detected in about 30% of the arthritic fluids.
TL;DR: All attempts to find a (Na+-K+)-activated, ouabain-inhibited, ATPase have been unsuccessful, in spite of the fact that living epimastigoes of T. cruzi are able to concentrate K+ and exclude Na+ from the medium.
Abstract: 1. 1. Subcellular fractions obtained from epimastigotes of Trypanosoma cruzi , disrupted by three different procedures, contained in addition to the already known Mg 2+ -activated adenosine triphosphatase (ATPase; E.C.3.6.1.4), a Ca 2+ -ATPase activity. 2. 2. The Ca 2+ -ATPase (a) was activated by low concentrations of CaCl 2 (apparent K a , 80 μM); (b) had a K a for ATP of 0.6 mM (at 1 mM CaCl 2 , pH 8.0); (c) presented a broad pH curve (optimum 7.1–8.6); and (d) was insensitive to oligomycin concentrations which inhibited the Mg 2+ -ATPase present in the same preparations. 3. 3. All attempts to find a (Na + −K + )-activated, ouabain-inhibited. ATPase have been unsuccessful, in spite of the fact that living epimastigoes of T. cruzi are able to concentrate K + and exclude Na + from the medium.
TL;DR: The results indicate that the chloroform-extracted enzyme is a soluble F1-ATPase similar to those isolated from mammalian mitochondria.
Abstract: 1. Grinding of epimastigotes of Trypanosoma cruzi with glass powder in a mortar yielded a Mg2+-activated adenosine triphosphatase (ATPase) preparation which was highly sensitive to oligomycin. 2. Chloroform treatment of the particles resulted in the solubilization of an ATPase which was (a) activated by MgCl2; (b) slightly inhibited by CaCl2; (c) activated by sulphite and bisulphite; (d) had an optimum pH of 7.6; and (e) had a Km for ATP of 2.1 mM (in the presence of 4 mM MgCl2). 3. The solubilized enzyme was insensitive to oligomycin and leucinostatin, which inhibited the membrane-bound ATPase, though inhibited by efrapeptin and quercetin. 4. The results indicate that the chloroform-extracted enzyme is a soluble F1-ATPase similar to those isolated from mammalian mitochondria.
TL;DR: It is indicated that, in the inner membrane, apoHBD interacts with the whole length of the fatty acyl chain and, consequently, is sensitive to phase transition.
TL;DR: Spontaneous motility of epididymis is possible in the presence of smaller amounts of endogenous prostaglandins, and sudden contraction occurring during ejaculation, induced by sympathetic and parasympathetic nerves stimulation, could be influenced or modulated by prostag landins.
Abstract: Prostaglandins E2 and F2α tromethamine salt caused an increase in amplitude and frequency of rat epididymal contractions. Moreover, they caused a significant potentiation of contractile responses of epididymal smooth muscle to stimulation by norepinephrine or acetylcholine. Indomethacin treatment caused no changes in the spontaneous motility, and this inhibitor of prostaglandins synthesis decreased the responses of epididymis to norepinephrine or acetylcholine. Spontaneous motility of epididymis is possible in the presence of smaller amounts of endogenous prostaglandins, and sudden contraction occurring during ejaculation, induced by sympathetic and parasympathetic nerves stimulation, could be influenced or modulated by prostaglandins.
TL;DR: Human red cells containing low ATP and high Pi concentrations were suspended in media with and without 2mm Ca2+, and the incorporation of (32P)Pi into ATP was measured, consistent with the idea that Ca2-dependent incorporation of Pi into ATP is catalyzed by the Ca2+ pump using energy derived from theCa2+ concentration gradient.
Abstract: Human red cells containing low ATP and high Pi concentrations were suspended in media with and without 2mm Ca2+, and the incorporation of (32P)Pi into ATP was measured. There was some incorporation whatever the medium, but in every experiment there was an extra incorporation when the cells were in the Ca2+-containing medium. This extra incorporation was abolished by the ionophore A23187, which collapses the Ca2+ concentration gradient across the membranes, or by LaCl3, which blocks the Ca2+ pump. Starved and phosphate-loaded cells also show an uptake of Ca2+ which is not apparent in fresh cells. Results are consistent with the idea that Ca2+-dependent incorporation of Pi into ATP is catalyzed by the Ca2+ pump using energy derived from the Ca2+ concentration gradient.
TL;DR: The absence of fibrin degradation products in serum suggests that there is no intravascular fibrIn deposition in this experimental model of hemorrhagic fever, and this finding was confirmed by histologic studies.
Abstract: is indicated by the presence of fibrin monomers. It is probable that the initial decrease in the number of platelets may be related to impaired production in the bone marrow as has been shown by other investigators. The absence of fibrin degradation products in serum suggests that there is no intravascular fibrin deposition in this experimental model of hemorrhagic fever. This finding was confirmed by histologic studies. Thrombocytopenia and alteration of results in blood clotting tests with decreased levels of coagulation factors were reported in patients with Argentine hemorrhagic fever (AHF) [1]. In some patients, an ongoing process of consumption coagulopathy was suggested by the presence of fi
TL;DR: In the Ca2-ATPase of human red cells the rate of dephosphorylation of the phosphoenzyme is increased by ADP, provided Ca2+ is present, which suggests that phosphorylations of theCa2+- ATPase is a reversible process.
Journal Article•
TL;DR: Ribonucleic acid extracts obtained from the lymph nodes and spleens of guinea pigs, which were immunized with testicular antigen emulsified in Freund's complete adjuvant, developed a delayed hypersensitivity to sperm antigens and testicular lesions which resembled the lesions obtained in the donor RNA guinea pig.
Abstract: Ribonucleic acid extracts (RNA) obtained from the lymph nodes and spleens of guinea pigs, which were immunized with testicular antigen emulsified in Freund's complete adjuvant (FCA), were injected intraperitoneally into normal guinea pigs. The transferred guinea pigs developed a delayed hypersensitivity to sperm antigens and testicular lesions which resembled the lesions obtained in the donor RNA guinea pigs. When the transfer was performed with RNA extracted from guinea pigs immunized with FCA alone or with 'immune' RNA treated with Ribonuclease, neither cellular immunity nor testicular lesions were observed.
TL;DR: In vivo activity of olivacine does not parallel its in vitro effects suggesting inactivation of the drug by the host, and ultrastructural and metabolic alterations in Trypanosoma cruzi epimastigotes are observed.
TL;DR: The magnitude of the equilibrium distribution between the normal and tautomeric proton positions of minimum energy is consistent with the idea that simultaneous double proton tunneling in the ground state is not significant, thus ruling out a possibility for an error mechanism in the genetic code.
TL;DR: The receptors that bind lactogenic hormones have been solubilized from adult female rat liver microsomes with 1% (wt/v) Triton X-100 and retained their specificity for lactogenic hormone binding.
TL;DR: In this article, the sodium salt of diethyl malonate 2-14C in decaline was used to obtain 3-dimethylaminomethyl-5-benzyloxy-6-azaindole-2-carboxy-late.
Abstract: Ethyl 3-dimethylaminomethyl-5-benzyloxy-6-azaindole-2-carboxy-late was condensed with the sodium salt of diethyl malonate-2-14C in decaline, and ethyl 5-benzyloxy-2-ethoxy carbony 1–6-azaindole-3-(2′-ethoxycarbonyl) propionate-2′-14C hydrochloride was obtained in good yield. Further treatment of the labelled azaindole with acid afforded the labelled 6-azaindanone which was reduced to 5-carboxyporphobilinogen lactam. Decarboxylation and saponification of the latter afforded porphobilinogen-9-14C with an overall yield of 27% in the five labelled steps.
TL;DR: Blood volume and iron kinetics were determined in three specimens of Bradypus tridactylus which were obtained in the coastal north-east regions of Brazil and the plasmaIron turnover rate was calculated to be 165.6 μg/kg per day and the red cell iron turnover rate 102.7 μg/ kg per day.
TL;DR: Results demonstrate that meperidine in standard classical doses is a potent inhibitor of BAO in man.
Abstract: Meperidine is a potent narcotic related chemically and pharmacologically to morphine and atropine. To examine its gastric antisecretory activity a study designed to test the effect of meperidine on basal acid secretion was carried out: 100 mg of meperidine given intramuscularly reduced basal acid output (BAO) by 66.3% at 1 hr (P<0.001), 64.9% at 2 hr (P<0.001), and 44.9% at 3 hr (P=0.005). This degree of reduction of BAO by this dose of meperidine did not differ from that produced by 30 mg of propantheline intramuscularly. These results demonstrate that meperidine in standard classical doses is a potent inhibitor of BAO in man.
TL;DR: In this article, the CNDO/2 MO and INDO MO methods were used to study the molecular electronic structure of the bicyclic molecules derived by transannular interaction of the amide groups in two isomeric dioxodiazacyclo-decanes.
TL;DR: In this article, 3-azido-3-deoxy-1,5,6-tri-O-(methylsulfonyl)-muco-inositol and its 2,4-diacetate are also described.
TL;DR: After chronic Administration of sodium barbitone to rats, a marked increase incorporation of [14C]-Leucine into isolated nerve endings was observed and chronic administration of the barbiturate produced a decreased incorporation in mitochondrial and microsomal fractions.
Abstract: After chronic administration of sodium barbitone to rats, a marked increase incorporation of [14C]-Leucine into isolated nerve endings was observed. Withdrawal of the drug resulted in a decreased incorporation with respect to values obtained with chronic ingesting animals. On the other hand chronic administration of the barbiturate produced a decreased incorporation in mitochondrial and microsomal fractions. These results are discussed in relation to the development of tolerance and abstinence syndrome to this drug.