Showing papers by "University of Bologna published in 1972"
TL;DR: The enzyme appears as an oxidase in the supernatant of rat heart, intestine, spleen, pancreas, lung and kidney and the enzyme of all organs but intestine can be converted into a dehydrogenase by dithioerythritol.
Abstract: 1. The ;xanthine oxidase' activity of rat liver supernatant, most of which behaves as an NAD(+)-dependent dehydrogenase (type D) can be rapidly converted into an oxidase (type O) by thiol reagents such as tetraethylthiuram disulphide, copper sulphate, 5,5'-dithiobis-(2-nitrobenzoic acid), N-ethylmaleimide and p-hydroxymercuribenzoate. Treatment with copper sulphate, if prolonged, leads to almost complete inactivation of the enzyme. The effect of these reagents is prevented by dithioerythritol, and in all cases but that of N-ethylmaleimide is reversed by the same thiol. 2. Dithioerythritol prevents and reverses the conversion of xanthine oxidase from type D into type O brought about by storage of rat liver supernatant at -20 degrees C, preincubation under anaerobic conditions, treatment with carbon or with diethyl ether, and reverses, but does not prevent, the conversion obtained by preincubation of the whole liver homogenate. 3. Conversion of the enzyme from type D into type O is effected by preincubation of rat liver supernatant with the sedimentable fraction from rat liver but not from chick or pigeon liver. The xanthine dehydrogenase activity of chick liver supernatant is not changed into an oxidase by preincubation with the sedimentable fraction from rat liver. 4. The enzyme activity of rat liver supernatant is converted from type D into type O during purification of the enzyme: the purified enzyme can be reconverted into type D by dithioerythritol. 5. The enzyme appears as an oxidase in the supernatant of rat heart, intestine, spleen, pancreas, lung and kidney. The enzyme of all organs but intestine can be converted into a dehydrogenase by dithioerythritol.
410 citations
195 citations
TL;DR: In the course of numerous polygraphic recordings made on normal subjects and patients with sleep disturbances, several vegetative and somatic phenomena which tended to oscillate or repeat themselves periodically every 20–30 sec during sleep are observed.
190 citations
TL;DR: Fast wave sleep is associated with changes in the regulation of postural, respiratory and thermoregulatory muscle activities in unrestrained cats sleeping at different environmental temperatures.
107 citations
TL;DR: It is suggested that the hepatotoxic actions of allyl alcohol and ofallyl formate on rat liver are related to their conversion into acrolein.
Abstract: 1. Acrolein was detected in rat liver suspensions incubated in the presence of allyl alcohol and allyl formate. Acrolein was determined by condensation of the distilled aldehyde with semicarbazide, followed by spectrophotometric measurement of the semicarbazone at 257nm and identification by paper chromatography. 2. The transformation of allyl alcohol into acrolein occurred in the presence of NAD(+). Inhibitors of rat liver alcohol dehydrogenase inhibited the reaction. 3. It is suggested that the hepatotoxic actions of allyl alcohol and of allyl formate on rat liver are related to their conversion into acrolein.
91 citations
TL;DR: In this paper, the authors studied deep-focus earthquakes in the Lipari Islands from the point of view of high-frequency S-wave attenuation and interpreted the results on the basis of plate-tectonics theory, and allowed the definition of a 3D model of the deep structure of this area.
87 citations
TL;DR: The observation that the breaks in the Arrhenius plots for membranous enzymes fall at different temperatures suggests caution in their correlation with phase transitions of membrane phospholipids.
81 citations
TL;DR: In this article, a critical study of the behavior of a massive spin two charged particle in an external electromagnetic field is made, and a unique Lagrangian which does not increase the number of degrees of freedom required for the description of a spin two particle is presented.
60 citations
TL;DR: In this article, preliminary results on the production of negative particles in inclusive reactions at intermediate angles (80 − 200 mrad) at the CERN ISR are reported. But the antiproton production cross-sections are apparently larger than smaller energies.
55 citations
TL;DR: The study shows that, starting from Stage 10, the notochord cells become hypertrophic and acquire the characteristics of secretory elements, with the production of chondroitin sulphate (A and/or C) and probably of collagen microfibrils.
Abstract: The author examines by means of ultrastructural, histochemical and autoradiographic techniques the development of the notochord of the chick embryo in the period between Hamburger-Hamilton's Stages 9 and 26. The interest in this research is that, during this period, the notochord is transformed from an apparently undifferentiated organ into an organ with secretory activity, and at the same time becomes an inductive organ in the development of the axial skeleton. The study shows that, starting from Stage 10, the notochord cells become hypertrophic and acquire the characteristics of secretory elements, with the production of chondroitin sulphate (A and/or C) and probably of collagen microfibrils. Such substances not only cluster densely around the notochord, thus contributing to the formation of the perichordal sheath, but they also diffuse outwards, becoming distributed among the sclerotomic cells; the latter, on the other hand, start to differentiate into cartilaginous cells only after the halo deriving from the notochord has enlarged and diffused among them. It is also pointed out that there is a close temporal connection between the high degree of secretory activity of the notochord and the start of its inductive activity on the sclerotomes.
54 citations
TL;DR: The cytological study of the maturation of summer and winter eggs of an italian population of this species has shown that both types of eggs undergo only one maturation division of equational type with the expulsion of only one diploid polar body.
Abstract: The cladoceran Daphnia middendorffiana is an arctic species able to produce winter eggs which develop parthenogenetically. The cytological study of the maturation of summer and winter eggs of an italian population of this species has shown that both types of eggs undergo only one maturation division of equational type with the expulsion of only one diploid polar body, the same maturation process as had been found in the pseudosexual eggs of a race of Daphnia pulex (Schrader, 1925).—The chromosomes behaviour during the maturation of summer and winter eggs of D. middendorffiana has been compared with that of a population of D. pulex which shows a normal heterogonic cycle.
TL;DR: In this paper, the authors re-examine the mantle core discontinuity and conclude that it is a composition discontinuity rather than a phase transition, and they further conclude that the mantle-core discontinuity is not a transition phase transition.
Abstract: We re-examine the problem of the mantle-core discontinuity. By means of theoretical equations of state for silicates in the metallic form, we conclude, once more, that it is a composition discontinuity rather than a phase transition.
TL;DR: Chitosan treated with copper sulphate exhibits a new crystal structure and a distinctive infrared spectrum, is quite stable and does not shrink, and is proposed as a chromatographic support for ligand-exchange chromatography.
TL;DR: ATPase activity of photosynthetic membrane fragments from the bacterium Rhodopseudomonas capsulata can be stimulated by continuous illumination under conditions of active cyclic electron flow and it is demonstrated that oxidized DCIP acts as an uncoupler of bacterial photophosphorylation.
TL;DR: An o -diphenol oxidase extracted from sweet cherry fruits was purified 17-fold, and the recovery of enzyme activity was 5·6%, probably due to steric hindrance.
TL;DR: In this paper, it was shown that the generation current is proportional to the depletion layer width rather than to W and the current-capacitance product must be expected to vary as the ratio W i W, which is all but constant with the applied voltage.
Abstract: In a reverse-biased p-n junction, the current component arising from carrier generation in the depletion layer has been up to now considered proportional to the depletion layer width W. As the junction capacitance varies inversely with W, the current-capacitance product should be constant with the applied voltage whenever the reverse current is essentially a generation current. There is experimental evidence, however, that this is not so. In the present paper it is shown that an important cause of such a discrepancy is the considerable difference existing between the depletion layer width and the width Wi of the region in which the generation function reaches its maximum value. In fact, the generation current is proportional to Wi rather than to W and the current-capacitance product must be expected to vary as the ratio W i W , which is all but constant with the applied voltage. A simple model is proposed for evaluation of the generation current effective width Wi, which has been explicitly computed as a function of the applied reverse voltage and of the doping profile in cases of abrupt and linearly-graded junctions.
01 Jan 1972
TL;DR: In this article, the aim of these researches on dehydrogenation reactions is not confined to the solution of technological problems, however, and the results have allowed important contributions to some aspects of the theory of heterogeneous catalysis to be obtained.
Abstract: Reactions involving hydrogenation and dehydrogenation are employed particularly in the petrochemical industry. Among these the dehydrogenation of butane over chromia-alumina catalysts plays an important role, because it represents the most important process for obtaining butenes and butadiene. Due to their practical interest, such processes have been the object of extensive investigations. The aim of these researches on dehydrogenation reactions is not confined to the solution of technological problems, however, and the results have allowed important contributions to some aspects of the theory of heterogeneous catalysis to be obtained.
TL;DR: In this work, atebrine fluorescence in chromatophores is shown to change with changes in the energetic state of phosphorylating membrane systems, and the mechanism of ate brine uptake is similar to that previously pro- posed for uptake of other amines by illuminated chloroplasts.
TL;DR: The reversible resolution of light dependent phosphorylating systems in cells of the non-sulfur purple bacterium Rhodopseudomonas capsulate has been recently achieved and a coupling factor was isolated, whose main characteristics can be summarized as follows.
TL;DR: It was found that, during the first day of withdrawal, the mean leverpressing rate of the morphine group decreased significantly, indicating that an “abstinence syndrome” in rats can be detected by means of an operant behavior technique.
Abstract: Rats previously trained to a fixed-ratio schedule (FR 50) were treated twice daily with saline or morphine sulfate (final dose, 40 mg/kg IP) for 20 days. On Days 21, 22, and 23, the morphine-treated animals received saline instead. Operant behavior was recorded during the first 14 days of treatment and again on Days 19-23. It was found that, during the first day of withdrawal, the mean leverpressing rate of the morphine group decreased significantly, indicating that an “abstinence syndrome” in rats can be detected by means of an operant behavior technique.
TL;DR: In this paper, a bubble chamber experiment was described in which observations were made of positive kaon interactions in deuterium and partial cross sections were given at 13 kaon momenta in the range 0.64-1.51 GeV/ c.
TL;DR: In this article, a high-resolution vacuum infrared spectrograph equipped with a liquid-helium-cooled Ge:Cu detector was used to detect dideuteroacetylene (C2D2) at 18.6 µm.
TL;DR: This preliminary study demonstrates time relationships between tonic and phasic components of FS, but very complex ones, the mechanisms of which deserve further investigation.
TL;DR: The results led to suggest that in non-sulfur purple bacteria functional interchangeability between coupling factors of photosynthesis and respiration exists, and were supported by the demonstration that an antibody against photosynthetic coupling factor could inhibit indifferently photophosphorylation in pigmented membranes and oxidative phosphorylated in aerobic membranes.
TL;DR: In this paper, the rotational constants B and C and the nuclear quadrupole coupling constants of six isotopic species of monochloroamine have been obtained from low Jμ a R branch transitions.
TL;DR: Le cellule a secretina vengono identificate con l'immunofluorescenza nella mucosa duodenale e digiunale di maiale facendo uso di antisieri anti-secretina sintetica porcina.
Abstract: Le cellule a secretina vengono identificate con l'immunofluorescenza nella mucosa duodenale e digiunale di maiale facendo uso di antisieri anti-secretina sintetica porcina. Parallele ricerche ultrastrutturali consentono di identificare in un tipo peculiare di cellular endocrina l'equivalente ultrastrutturale della cellular a secretina.
TL;DR: The hypothesis is advanced that superficial proteins are linked to the mitochondrial membrane by other types of bonds and the importance of hydrophobic interactions between phospholipids and proteins in mitochondria is discussed.
TL;DR: In this article, the motion of high-energy particles and photons in a giant vortex around the axis of symmetry above and below the equatorial plane, dragged by the gravitational field, is analyzed in the Kerr metric with the use of first integrals.
Abstract: The motion is analysed, in general, in the Kerr metric with the use of first integrals. Some of the high-energy particles and photons are found to move in a giant vortex around the axis of symmetry above and below the equatorial plane, dragged by the gravitational field.
TL;DR: In this article, the dynamic problem of rigid plastic structures subjected to impulsive loading is discussed in matrix notation on the basis of finite element discretization of the structure and piecewise linear approximation of the yield surfaces, using some quadratic programming concepts.
Abstract: This paper discusses the dynamic problem of rigid plastic structures subjected to impulsive loading. A couple of “dual” extremum theorems reduces the problem to the optimization of convex quadratic functions subject to linear inequalities and equations: the first theorem takes as variables stress and accelerations, the second accelerations and plastic multiplier rates. The problem is discussed in matrix notation on the basis of finite element discretization of the structure and piecewise linear approximation of the yield surfaces, using some quadratic programming concepts. The procedure is illustrated by a simple numerical example.
TL;DR: In the habituated tissue and crown gall of Scorzonera hispanica, cultivated in vitro, two polyamines occur in larger amounts than in the normal tissue, the greatest increase being found in the crown gall tumor.