Showing papers by "University of Valencia published in 1982"
TL;DR: In this paper, two pseudoclassical particle models invariant under extended Poincare supersymmetry with central charges were proposed, in which the central charge provided the mass term breaking the U(n) internal symmetry and in the second model the u(n ) symmetry was preserved.
156 citations
TL;DR: In this article, the experimental distributions of 25 MeV α-particles scattered from 28 nuclei ranging from 50Cr to 93Nb have been measured and then analyzed in terms of a regular optical model with standard Woods-Saxon geometries for both the real and imaginary potentials.
37 citations
TL;DR: It is concluded that β‐adrenoceptor agonists exert preventive and curative effects on gastric damage induced in the rat, and this effect seems specific and mediated through β‐adsenoceptor activation.
Abstract: 1. Experiments were designed to evaluate the effect of the pharmacological activation of beta-adrenoceptors on various models of gastric ulcer in the rat. 2. Pretreatment with the beta-adrenoceptor stimulant drugs, isoprenaline or salbutamol, significantly inhibited stress-induced gastric ulcers. This anti-ulcer effect was abolished by propranolol but not by atenolol, suggesting that beta 2-adrenoceptors mediate this response. 3. In the pylorus-ligation model, salbutamol inhibited lesion formation and reduced the intragastric content of hydrogen ions, histamine and pepsin although the latter was only affected with the higher dose of salbutamol. 4. Salbutamol also prevented the ulcerogenic action on the gastric mucosa of an exogenously perfused artificial gastric juice, showing that the anti-ulcer effect is not necessarily dependent on acid inhibition. 5. Salbutamol also reduced the formation of acute ulcers induced by various iatrogenic means (histamine, polymyxin B, reserpine and indomethacin). 6. Long-term treatment with salbutamol accelerated the healing of experimental chronic gastric ulcer. 7. In anaesthetized rats, salbutamol produced a dose-related increase in mucosal blood flow which may contribute to its mode of action. 8. It is concluded that beta-adrenoceptor agonists exert preventive and curative effects on gastric damage induced in the rat. This effect seems specific and mediated through beta-adrenoceptor activation.
33 citations
TL;DR: In this article, the kinetic rate constants for cracking, isomerization, and disproportionation of n-heptane over a CrHNaY (32% chromium exchanged) zeolite catalyst at 400, 450, and 470 °C have been calculated.
26 citations
TL;DR: In this paper, it was reported that tetrahydrofuran was the solvent of choice for the formation of the mono-lithiated pyrrole derivative and that the rate of the metallation was accelerated by the presence of TMEDA.
26 citations
TL;DR: The results suggest that at least part of the mannoproteins initially found in the periplasmic space may move into the wall, and the time lag between the addition of the radioactive precursors and their incorporation in the cell envelope indicates that protein formation and carbohydrate incorporation take place in succession.
Abstract: By pulse and chase labeling experiments, two independent mannoprotein pools have been found associated with the Saccharomyces cerevisiae envelope. One of them probably corresponds to mannoproteins localized in the periplasmic space. These molecules showed a high turnover rate at 28° C. The second pool is formed by intrinsic wall mannoproteins which are apparently stable for long periods of time, after a small initial turnover. These results suggest that at least part of the mannoproteins initially found in the periplasmic space may move into the wall.
25 citations
TL;DR: In this paper, a survey of the normal histology was developed based not only on normal adult histological structures but also on reparative tissues, as in chronic inflammatory reactions of the gingival mucosa, regenerative tissue of wounds and in chronic osteomyelitis.
Abstract: Summary The vascular tumors are morphologically recognized by their ability to configurate complete or atypical angiomatous structures. Based on our personal experience of 42 cases of benign and malignant angiomatous tumors, we discussed several aspects of their histogenesis and its morphology when studied with transmission and scanning electron microscopy. Therefore, a survey of the normal histology was developed based not only on normal adult histological structures but also on reparative tissues, as in chronic inflammatory reactions of the gingival mucosa, regenerative tissue of wounds and in chronic osteomyelitis. Supported by morphological arguments, we postulate the existence of several endothelial cell subpopulations, which are involved through several ways in tumoral angiogenesis. This fact is clearly seen in benign capillary angioma, in pseudopyogenic granuloma of the skin and in cellular angioma of infancy. Among the malignant vascular tumors, the hemangiopericytoma shows a large cell heterogeneity, dilating from well developed pericytes to fusocellular and anaplastic ones; well differentiated hemangiopericytoma keeps an epithelial-like appearance and its cells surrounded by basement membranes. It seems possible to distinguish an hemangioendothelioma from an angiosarcoma (hemangiocarcoma). Both are angiogenic neoplasms of malignant nature, but the first is mainly composed by transformed endothelial cells of a mesenchymal nature, similar to those seen in embryonic angiogenesis. The second tumor type possesses not only endothelial cells but also mesenchymal angioblasts from which other cells derivatives are conformed as atypical pericytes. Furthermore, in some cases angiosarcoma displays embryonic metaplastic hematopoiesis (erythropoiesis) inside the neoformed stroma. Histogeneis of Kaposi sarcoma of the skin remains a matter of controversy. The histiocytic endothelial cells could be considered as the primitive endothelial cell subpopulation from which this tumor group could be originated. Bone vascular tumors adopt a more specific texture. Particular emphasis is given to the angiogenic variant of Ewing's sarcoma, from which three cases have been isolated among the 219 neoplasms reviewed.
23 citations
TL;DR: Hypericum ericoides contains quercetin, hyperin, kielcorin and a new flavone, identified as 5,4′- dihydroxy-7-methoxy-6-methylflavone or 6- C -methyl-7 O -methylapigenin this paper.
21 citations
TL;DR: The new method consists of the addition of sodium novobiocin to a modification of Rappaport's medium, which allows a better recovery of salmonellas from water than selenite broth.
Abstract: A new enrichment procedure for the recovery of salmonellas from aquatic environments is proposed. It has been tested in a eutrophic lake showing moderate to high faecal contamination levels (the Albufera lake near Valencia, Spain), and in effluents coming into a wastewater treatment plant. The new method consists of the addition of sodium novobiocin to a modification of Rappaport's medium (R10/43°C). The new medium (NR10/43°C) allows a better recovery of salmonellas from water than selenite broth.
21 citations
TL;DR: The results suggest that some step common to the biogenesis of quite different kinds of envelope protein is blocked by the presence of the hybrid protein, and may indicate that the assembly of these membrane proteins is blocked at a relatively late step rather than at the level of primary recognition of some site by the signal sequence.
Abstract: The synthesis of a membrane-bound MalE beta-galactosidase hybrid protein, when induced by growth of Escherichia coli on maltose, leads to inhibition of cell division and eventually a reduced rate of mass increase. In addition, the relative rate of synthesis of outer membrane proteins, but not that of inner membrane proteins, was reduced by about 50%. Kinetic experiments demonstrated that this reduction coincided with the period of maximum synthesis of the hybrid protein (and another maltose-inducible protein, LamB). The accumulation of this abnormal protein in the envelope therefore appeared specifically to inhibit the synthesis, the assembly of outer membrane proteins, or both, indicating that the hybrid protein blocks some export site or causes the sequestration of some limiting factor(s) involved in the export process. Since the MalE protein is normally located in the periplasm, the results also suggest that the synthesis of periplasmic and outer membrane proteins may involve some steps in common. The reduced rate of synthesis of outer membrane proteins was also accompanied by the accumulation in the envelope of at least one outer membrane protein and at least two inner membrane proteins as higher-molecular-weight forms, indicating that processing (removal of the N-terminal signal sequence) was also disrupted by the presence of the hybrid protein. These results may indicate that the assembly of these membrane proteins is blocked at a relatively late step rather than at the level of primary recognition of some site by the signal sequence. In addition, the results suggest that some step common to the biogenesis of quite different kinds of envelope protein is blocked by the presence of the hybrid protein.
20 citations
TL;DR: A short route to the 2-azabicyclo[3.3.1]nonan-7-one system is described in this paper, where the Fischer indole synthesis from 4-piperidones with diethyl 2-oxopropylphosphonate, followed by catalytic hydrogenation furnished the corresponding piperidylpropanones 6 which were cyclized with mercuric acetate in acetic acid to the target target bicyclic ketones.
01 Jan 1982
TL;DR: In this paper, a stoichiometric and kinetic study of the 99mTc-DMSA complex obtained in the presence of large amounts of Sn2+ was made and the Tc oxidation state is 3+.
TL;DR: In this article, a nueva family parametrica de distribuciones, which contiene a uniforme como caseo particular, is proposed. But it is not clear how to compare it with a modelo probabilistico.
Abstract: Se pone de manifiesto que el problema de contrastar si un conjunto de datos es o no compatible con un modelo probabilistico totalmente especificado puede ser reducido al problema de contrastar si una determinada transformacion de los datos puede ser considerada como una muestra aleatoria de una distribucion uniforme. Mediante la construccion de una nueva familia parametrica de distribuciones, que contiene a la uniforme como caso particular, se propone un contraste bayesiano de uniformidad que constituye una alternativa a los metodos clasicos para el contraste de modelos probabilisticos.
01 Jan 1982
TL;DR: The puffing pattern of several chromosomal rearrangements of the J and U chromosomes of Drosophila subobscura shows a rich chromosomal polymorphism and the standardization of apuffing pattern in this species important.
Abstract: The puffs and Balbiani rings are the visible expression of sites of genetic activity (Beerman, 1952). Since Beermann’s original hypothesis, puffing patterns for several species of Diptera have been described. Thus for the genus Drosophila, Ashburner (1967, 1969a and 1969b) has reported the puffing pattern of Drosophila melanogaster and Drosophila simulans, Beredens (1965) of Drosophila hydei, and Moriwaki and Ito (1969) of Drosophila ananassae. In a previous paper Frutos and Latorre (1981) have determined puffing patterns of the J and U chromosomes of Drosophila subobscura. This species shows a rich chromosomal polymorphism and the puffing pattern of several chromosomal rearrangements of the J and U chromosomes were studied. In spite of the fact that not much variability was found, we consider the standardization of a puffing pattern in this species important.
TL;DR: In this paper, the method of multiple linear regression was applied to the spectrophotometric determination of the protonation constants and the molar absortivity coefficient of the monoprotonated species of diprotic acids.
TL;DR: In the U chromosome, the U1−2 and U1+2+8 arrangements show the same puffing pattern, and neither quantitative nor qualitative differences were found, however, thepuffing pattern of these chromosomes alters considerably in the Ust arrangement of the K228 laboratory strain.
Abstract: A study of the puffing patterns of the Jst, J1, U1−2, U1−2−8 and Ust chromosomal arrangements of Drosophila subobscura, from different geographical origins, has been carried out. Twenty-eight puffs were observed, 10 on the J chromosome, and 18 on the U chromosome. No differences, whether qualitative or quantitative, have been found between the puffing pattern of the J chromosome, whether from the same of different geographical background. In the U chromosome, the U1−2 and U1+2+8 arrangements show the same puffing pattern, and neither quantitative nor qualitative differences were found. However, the puffing pattern of these chromosomes alters considerably in the Ust arrangement of the K228 laboratory strain.
TL;DR: Observations suggest that between the execution points of cdc 3 and cdc 10, essential processes in the assembly of cell membrane occur, and this may help to explain why these strains stop growing after 3 hours of incubation at the non-permissive temperature.
Abstract: The four temperature-sensitive mutants of Saccharomyces cerevisiae in the cell division cycle defective in cytokinesis (cdc, 3, 10, 11 and 12), have been analyzed with respect to the biosynthesis of the cell wall polymers. After 3 hours of incubation at the non-permissive temperature (37°C) these strains stop growing. The synthesis of glucan, mannan and chitin (wall polymers) level off in a similar time, but glucan, mannan and chitin synthases remained active for at least 4 hours.
TL;DR: In cultures growing at high, intermediate, and low rates, cell diameter does not change with length, which means that cells maintain a constant diameter during the cell cycle.
Abstract: Measurements of cell diameter and length inSalmonella typhimurium LT2 cells were correlated using both light and electron microscopy. In cultures growing at high, intermediate, and low rates, cell diameter does not change with length. This constancy is also maintained in septated cells before division. Since length increases continuously with cell age, the above observations mean that cells maintain a constant diameter during the cell cycle.
TL;DR: In this article, the formation of violurato complexes of Cr(III) has been studied in aqueous solution, and the acidity constants of this species have been determined: pKa1 = 3.32, pKa2 = 4.25,pKa3 =4.83 and pKa4 =6.99.
Abstract: The formation of violurato complexes of Cr(III) has been studied in aqueous solution. Two compounds, [Cr(H2V)3].5H2O and Na[Cr(H2V)2(OH)2].4H2O have been synthesized and characterized. [Cr(H2V)3] behaves in aqueous solution as a triprotic acid but it can also add a proton yielding [Cr(H2V)2(H3V)]+. The acidity constants of this species have been determined: pKa1 =3.32, pKa2 =4.25, pKa3 =4.83 and pKa4 =6.99 (25°C, 0.1 M NaC1O4). [Cr(H2V)2(OH)2]− undergoes a deprotonation of the two H2V− ligands and a protonation of the hydroxo ligands. The acidity constants of [Cr(H2V)2(H2O)2]+ have been also determined: pKa1 =3.5, pKa2 =4.6, pKa3 =7.1 and pKa4 =9.2 (25°C, 0.1 M NaC1O4). The coordination of a violuric acid molecule as a neutral ligand is reported for the first time.
TL;DR: It has been found that the final concentration of alpha-galactosidase produced by induced cells when transferred at the non-permissive temperature is inversely proportional to the incubation time in glucose.
TL;DR: In this paper, the photo-Fries rearrangement of methoxybenzophenone has been used to obtain high yields in hexane and methanol, but the yields are low in methanoline.
TL;DR: In this paper, a Bayesian solution to the Fieller-Creasy problem for the case in which the variances are not assumed equal is presented. But the solution is not suitable for the non-informative prior distributions.
Abstract: The problem of making inferences about the ratio of two normal populations is usually known as the Fieller-Creasy problem, and it gave rise to a controversy among fiducialists and confidence-intervalists. A Bayesian solution to such a problem when the two normal populations have the same unknown variance was presented by Bernardo (1977) using reference non-informative prior distributions. The solution to the case in which the variances are not assumed equal is obtained here. Some numerical results for artificial populations are given
TL;DR: The peptide composition of plasma membrane in Saccharomyces cerevisiae cells growing at different temperatures between 18 and 38 degrees C was studied using SDS-polyacrylamide gel electrophoresis and the 80 kDa protein band was the only one with significant differential decay.
TL;DR: From the flowers of Acacia retinoide 6- C -glucosylnaringenin has been identified and it is suggested that this substance may be a phytochemical intermediate between glucose and glucose-like substances in the fruit extract of the tree.
TL;DR: Methods of simple and multiple linear regression applied to the potentiometric determination of protonation constants of diprotic and triprotic acids are studied critically and the best way of fitting the data, according to the order of magnitude of the constants, is established.
TL;DR: In this article, Bernardo et al. showed that the usual uniform prior for the mean is not sound, and that this prior must be modified by using the maximization of missing information procedure.
Abstract: If we are interested in making inferences about the square norm of the mean in a multivariate normal model, the usual uniform prior for the mean is not sound, as revealed by Stein in his 1959 work
This paper studies in what sense this prior must be modified by using the maximization of missing information procedure (Bernardo, 1979)
TL;DR: The electrophoretic pattern of the internal membranes revealed close similarities with that of the plasma membrane and though two-dimensional electrophoresis might disclose greater differences, these similarities suggest a common origin for most of the components of both membranous systems.
TL;DR: In this paper, the application of linear regression to the spectrophotometric determination of the protonation constant of an acid base system in strong acid and strong basic media is studied critically.