Showing papers by "University of Palermo published in 1969"

Purine and pyrimidine nucleotides in the brain of normal and convulsant rats.

Abstract: — Purine and pyrimidine nucleotides were measured in the brain of normal and electroshocked rats after chromatographic separation on ion-exchange resin of mono-, di- and tri-phosphorylated derivatives. CMP, IMP and NAD did not show any significant quantitative change. Adenine nucleotides showed an abrupt change followed by a rapid return to the control value. GTP was the only purine nucleotide exhibiting a relatively slow return to its starting concentration. The greatest percentage increase after electroshock was observed in UMP, which returned to its control value only after 5 min; UDPCoenzymes (i.e. UDPA plus UDPG) showed a relatively small drop during the development of the seizure and the slowest return to the base line; UTP showed a late transistory increase above the normal level after an initial drop associated with convulsant activity. Tritiated uridine was injected intracisternally to investigate the turnover of pyrimidine nucleotides. UTP showed the highest specific radioactivity at the earliest time, followed by UMP, UDPCoenzymes and CMP. It was found that convulsant activity is associated with dramatic changes in the specific radioactivity of pyrimidine nucleotides.

Limiting Conditions of Yielding for Anisotropic Materials

Abstract: The known Limiting Conditions of Yielding presuppose homogeneity andisotropy of the material. Formulas for anisotropic materials have been proposed: but they cannot be applied to all practical applications. The Limiting Condition of Yielding already proposed by the A. for isotropic materials can easily be extended to materials with different mechanical properties in different directions: the formulas obtained confirm the particular cases and the particular formulas already known for isotropic materials. The various solutions proposed by the A. for anisotropic bodies are usually represented by paraboloids whose characteristics obviously depend on the experimental parameters.

The Function of the Caudate Nucleus in the Control of Some Paroxystic Activities in the Neuraxis

Abstract: (1969). The Function of the Caudate Nucleus in the Control of Some Paroxystic Activities in the Neuraxis. Archives Internationales de Physiologie et de Biochimie: Vol. 77, No. 3, pp. 465-484.

Aspartate aminotransferase and carbohydrate metabolism of rat brain

Abstract: E stato determinato il rapporto tra forma «piridossalica» e forma «piridossaminica» dell'aspartato aminotransferasi nell'encefalo totale di ratti albini durante l'ipoglicemia da insulina e l'iperglicemia da allossana. Il rapporto tra le due forme catalitiche dell'enzima e stato considerato un indice dell'efficienza del ciclo degli acidi tricarbossilici, ed e stata prospettata la possibilita che l'aspartato aminotransferasi abbia una funzione regolativa nei riguardi del ciclo.

Drawing and extruding: Theoretical and approximate formulas

Abstract: The problem of drawing of wires and of strips has been treated in several studies; among these the studies of Sachs seem essential. However, the results deduced according to similar theories are not always in accordance with the experimental results: reduction of area or of thickness are in fact usually smaller than those resulting from the theory. This is in dependance of the fact that Sachs has adopted the Limiting Condition of Yielding by v. Mises, according to which the limit values of stress in traction and compression are equal. More recently other AA. (Alberti, Noto La Diega, Bugini), admitting the Limiting Condition of Yielding by A. (or of the Paraboloid of Revolution) of which we have treated in one of our previous works, attain results tallying with the experience. In the present study the above said subjects are treated as to evidence their unitarian signifiance and clarify their several aspects. The approximate formulas proposed by A. result of easy and quick application. In the same manner are treated other problems, among which the problem of the extrusion (Bagarello, Ammendola).

Aspartate aminotransferase in brain tissue cultures.

Abstract: SOME 8 years ago JENKINS and SIZER (1960) reported direct spectrophotometric evidence for the reversible interconversion between the ‘pyridoxal’ and ‘pyridoxamine’ forms of aspartate aminotransferase (~-aspartate-2-oxoglutarate aminotransferase; EC 2.6.1.1.). In vitro findings indicated that an increase of keto acids is responsible for a shift of the enzyme from the ‘pyridoxaniine’ toward the ‘pyridoxal’ form (JENKINS and SIZER, 1960). Evidence for the occurrence in vivo of such an interconversion has since been obtained (BONAVITA, GUARNERI and SCARDI, 1964). Since the level of substrates participating in the transamination reaction modifies the ratio between the ‘pyridoxal’ and ‘pyridoxamine’ form of the enzyme, the ratio can be regarded as a valuable index in vivo of the steady level of keto acids in the tissue, which in turn is regulated by the rate of flux in the citric acid cycle (GOLDBERG, PASSONEAU and UWRY 1965). The present communication describes the early occurrence of changes of the ‘pyridoxal’ ‘pyridoxamine’ ratio in primary cultures of brain cortex from adult and new-born rats, in contrast with an ependymoma originally induced by the intracerebral implantation of methylcholanthrene into a C57B1/6J mouse at the laboratories of Dr. H. M. Zimmerman (Montefiore Hospital, Bronx, New York) (see ZIMMERMAN and MAIER, 194849), which does not undergo any change. A few years ago BORNSTEIN (1964) described the morphological development of neonatal mouse cerebral cortex in tissue cultures and found that there is practically no outgrowth during the first 2 days following explantation. In the present biochemical study, nervous tissues have been submitted to analysis soon after explantation, in an attempt to obtain data on the metabolic changes which occur before the outgrowth of neurites and the development of myelinated axons. A study of the ‘pyridoxal’/‘pyridoxamine’ ratio of aspartate aminotransferase soon after the explantation of mature and immature nervous tissues may contribute to the understanding of basic differences between these tissues and to answering the question as to whether or not metabolic changes in tissue cultures are only related to the environment.

Single giant larvae of Ascidia malaca from double eggs.

Abstract: E stata operata la fusione due a due di uova vergini diAscidia malaca. Le uova giganti cosi ottenute, sono state successivamente fecondate e il loro sviluppo e stato seguito. Da esse sono state ottenute in numerosi casi delle larve giganti che mostravano unicita in tutti i loro organi. L'osservazione dell'uovo gigante, dopo fecondazione, permette di asserire che le larve giganti sono triploidi.

Self-consistency conditions for localized magnetic moments in a free electron gas

Abstract: The self-consistent conditions for a localized magnetic moment in a metal are studied in the case where the density of states of the host metal is free electron like. A method is outlined which in principle allows to determine self-consistently in the Hartree-Fock approximation the relevant parameters of the magnetic ground state of the system. A numerical example is approximately worked out to show how the theory gives reasonable answers in spite of the crudeness of some of the approximations used.

Separation of principal stresses along sections of symmetry by means of isopachic patterns

Abstract: An approximate rapid method for the separation of principal stresses along sections of symmetry free from external loads is described. The method is based on the sum of principal stresses and checked by applying it to a circular ring under diametral compression and to a grooved bar in tension.