Showing papers by "National University of La Plata published in 1975"

Oxidative desaturation of α-linolenic, linoleic, and stearic acids by human liver microsomes

Abstract: The desaturation of stearic, linoleic, and α-linolenic acids by human liver microsomes were studied. The microsomes were isolated from liver biopsies obtained during operations. It was shown that human liver microsomes are able to desaturate 1-14C-α-linolenic acid to octadeca-6,9,12,15-tetraenoic acid; 1-14C-linoleic acid to γ-linolenic acid; and 1-14C-stearic acid to oleic acid in the same system described in the rat. However, the desaturation activity obtained was low compared to other mammals. This effect was attributed to fasting, premedication, or the anaesthesia.

Demonstration of intermolecular forces in cell adhesion using a new electrochemical technique.

Abstract: THE problem of cell adhesion has been approached from both chemical1–3 and physical4,5 viewpoints. We present here new evidence that a purely physical attraction acts between cells and other surfaces and that electrostatic forces can overcome this attraction. Previous attempts to demonstrate and interpret such forces6–8 have largely been frustrated by inadequately defined test surfaces, biological media including complex macromolecular components, and inappropriate assays for cell adhesion.

Dietary and hormonal effects upon activity of "soluble" protein and particulate fraction of fatty acid desaturation system of rat liver microsomes.

Abstract: Rat liver microsomes were extracted with a buffered 0.15 M KCl and 0.25 M sucrose solution and fractionated by centrifugation into a particulate component and a supernatant containing a protein factor necessary for fatty acid desaturation. The delta 6 fatty acid desaturation activity of the extracted microsomes was reduced significantly, and the readdition of the supernatant restored the enzymatic activity to the original value of the whole microsomes. A protein diet or a fat-free diet increased the delta 6 desaturation activity of the whole microsomes. The activating effect was evoked upon the particulate components of the enzymatic desaturation system and not upon the protein factor present in the supernatant. Fasting, refeeding, and refeeding plus glucagon and theophylline treatments of rats also modified the delta 6 desaturation activity of whole liver microsomes. The effect also was evoked on the delta 6 desaturation system tightly bound to the microsomal membrane but not on the protein factor of the supernatant. Accordingly, the protein factor of the supernatant is considered to be different from the cyanide sensitive factor and the desaturase.

Glycogen metabolism in muscle: Its circadian and seasonal variations

Abstract: The glycogen content of mice diaphragm and 14-C-glucose incorporation into glycogen was studied around the clock at 4-hr intervals. It was found that glycogen content presents a circadian rhythm with a peak value around 4 hr; this rhythm was reproduced in four different months, but with changes both in the absolute values and in the range of oscillation around the 24-hr mean value. Although labeled glucose incorporation exhibited a circadian variation as well, it peak value was 180 degrees out of phase compared with the glycogen rhythm. When the animals were submitted to a 29-hr fasting, the glycogen-24 hr-variation was still present, with similar oscillation around the mean. However, the absolute glycogen values were one-third as high as the ones obtained in the control animals. Our results suggest that the rhythm of glycogen content is due, at least partly, to the circadian variation of its synthesis. Furthermore, food intake is not the main factor responsible for the above mentioned rhythm.

Das thermische verhalten einiger "prussiate"

Abstract: Das thermische Verhalten einer Anzahl komplexer Verbindungen des Typs [FeII(CN)5L]5− wurde mittels thermogravimetrischer und Differential-Thermoanalyse untersucht. Eine einfache Korrelation zwischen der Zersetzungstemperatur und der Lage des Liganden L in der spektrochemischen Reihe konnte gefunden werden. Die aus dem Studium der festen Zersetzungsprodukte erhaltenen experimentellen Beweise gestatten es, einige Zersetzungsschemata aufzustellen.

Das Schwingungsspektrum von Magnesium-orthovanadat

Abstract: The infrared and laser-Raman spectra of crystalline Mg3(VO4)2 are reported and a factor group analysis for the full lattice is presented to support the discussion. The 1,000 to 600 cm−1 region of the spectrum is essentially related to internal (stretching) modes of the greatly distorted VO4 tetrahedra, whereas the bands in the low frequency region must be assigned to complex vibrations originating in the interaction of the bending vibrations of the tetrahedral groups with the external modes.

Das Schwingungsspektrum von Pb2V2O7

Abstract: The infrared and laser-Raman spectra of crystalline Pb2V2O7 are reported and discussed with the aid of a “Site Symmetry”-analysis.

Molecular weight distribution of native poly(D‐β‐hydroxybutyric acid)

Abstract: The molecular weight distribution of the biopolyester 1 from D-β-hydroxybutyric acid, isolated from Rhizobium meliloti by methods which preserved its native molecular properties, was studied. The weight average degree of polymerization is approximately DPw=23000, 1 being therefore one of the highest biopolymers with respect to chain length. The distribution of the degree of polymerization of 1 is distinguished by a great homogeneity, which it still possesses even after 30 hours of synthesis. One can conclude, therefore, that biosynthesis of an endogeneous bacterial polymer like 1 takes place also by a mechanism which produces molecules of homogeneous chain length, as e.g. a Possion type mechanism, and where the mean time of synthesis coincides approximately with the mean time of generation. Es wurde die Molekulargewichtsverteilung des Biopolyesters 1 aus D-β-Hydroxybuttersaure untersucht, der unter Erhaltung seiner nativen molekularen Eigenschaften aus Rhizobium meliloti isoliert worden war. Das Gewichtsmittel des Polymerisationsgrads liegt bei DPW=23000, weswegen man 1 als eines der hochstmolekularen Biopolymere ansehen kann. Die Kettenlangenverteilung von 1 weist auch noch nach 30 Stunden Synthesezeit eine auserordentlich grose Einheitlichkeit auf. Daraus last sich schliesen, das auch endogene bakterielle Polymere wie 1 nach einem Mechanismus synthetisiert werden, der einheitliche Molekule erzeugt. Dies kann ein Poisson-Mechanismus sein, bei dem die mittlere Synthesezeit in etwa mit der mittleren Generationszeit der Bakterien ubereinstimmt.

Protectins in Argentine Mollusks: Immunological and Immunochemical Aspects

Abstract: The agglutinating activities of the organs, fluids and spawn from snails and slugs toward various human blood groups has now been examined in detail. The effect of calcium salts and aspects of the variation of agglutinins and hemolysins between individuals of a single species or between species are described in the present paper. Two families of the order Stylommatophora, Vaginulidae and Strophocheilidae, as well as a family of subclass Prosobranchia, order Mesogastropoda, Ampullariidae, represent very primitive groups of the class Gastropoda native to Argentina. O. lactea and H. aspersa are introduced species well known with respect to their serological behaviour. They were studied for possible populational or geographic differences in reactivities. V. solea is a slug of not yet clear taxonomical classification. To some authors it belongs to a new order Systellommatophora which is different from Stylommatophora and Basommatophora (1). Borus, which is of a large size, has a number of morphological features that assign it to Strophocheilidae group A, the most primitive of the family (2).

Berechnung von mittleren Schwingungsamplituden einiger tetraedrischer Moleküle und Ionen nach der Methode der charakteristischen Schwingungen

Abstract: Mean amplitudes of vibration of a series of tetrahedralXY4 molecules and ions (hydrides, halides, oxides and oxoanions) have been calculated using the “Method of the Characteristic Vibrations” ofA. Muller. The results indicate that this method leads to very good values for most of the investigated species, and especially in the cases of highMX/MY mass ratio.

Tuber production by purple nutgrass (Cyperus rotundus L.) in darkness

Abstract: Summary: Resume: Zusammenfassung Observations were made on the development of new tubers from sprouts of isolated tubers of Cyperus rotundus grown in the dark. The metabolic events occurred primarily in the sprout itself, though the physiological state of the parent tuber affected the phenomenon. A seasonal variation in the behaviour of the sprouts was observed; maximum tuber formation was found in autumn and winter and minimum in spring and summer. The initiation of new tubers was independent of the sprout length and seemed rather to be dependent on its age. The physiological slate that enabled the sprouts to form tubers alternated with periods in which this condition was lost. Production de tubercules par le cyperus (Cyperus rotundus L.) a l'obscurite Des observations ont ete faites sur le developpement de nouveaux tubercules a partir de pousses de tubercules isoles de Cyperus rotundus croissant a robscurite. Les transformations metaboliques apparurent dans la pousse elle-meme, bien que le phenomene fut affecte par l'etat du tubercule parental. Une variation saisonniere fut observee dans le comportement des pousses: la formation maximale des tubercules fut constatee en automne et en hiver, la formation minimale au printemps et en ete. L'initiation d e nouveaux tubercules fut indeependante de la longueur de la pousse et sembla plutot dependre de son âge. L'etat physiologique, qui permet aux pousses de former des tubercules, alterna avec des peeriodes an cours desquelles cette faculte fut perdue. Knollenbildung bei Cyperus rotundus L. in Dunkelheit Es wurde die Entwicklung neuer Knollen aus den Sprossen von isolierten Knollen von Cyperus rotundus beobachtet, die bei Dunkelheit gewachsen waren. Die Stoffwechselprozesse verliefen hauptsachlich im Spross selbst, sie wurden aber vom physiologischen Zustand der Mutterknolle beeinflusst. Das Verhalten der Sprosse war von der Jahreszeit abhangig: die meisten Knollen wurden im Herbst und Winter, die wenigsten im Fruhjahr und Sommer gebildet. Die Bildung neuer Knollen war von der Sprosslange unabhangig und schien eher VOM Alter der Sprosse, abhangig zu sein. Der physiologische Zustand der Sprosse der sie zur Knollenbildung befahigte wechselte mit Perioden ab in denen keine Knollenbildung auftrat.

Darstellung, kristallographische Daten und IR-Spektrum von Mangan(II)-diarsenat

Abstract: Mn2As2O7 has been obtained by solid state reaction between As2O5 and MnCO3 at 600 °C and also by thermal decomposition of NH4MnAsO4·H2O. The crystallographic study has shown that the substance crystallizes in the monoclinic thortveitite structure. Its i.r. spectrum was recorded and discussed in relation with their structural properties. The i.r. spectrum of the parent compound NH4MnAsO4·H2O was also briefly discussed.

Second-class currents in 0−→0+ and unique nuclear β transitions

Abstract: The induced pseudotensor contribution to 0− → 0+ and uniqueβ transitions has been analyzed starting from two possible forms of the nonrelativistic Hamiltonian. The role of mesonic corrections and mesonic second-class currents has been discussed

Study of a Neutral Hydrogen Feature Previously Observed by Cugnon

Abstract: An anomalous velocity cloud nearl=349°,b=+3°, was investigated by Cugnon (1968). The authors made a new set of observations in order to obtain a more complete picture of the feature, including the region originally out of Cugnon's limit of observation. A comparison with optical and radio observations was made and several possibilities of interpretation as to the nature of the object were analyzed.

Galactic X-ray sources and the ionospheric D region

Abstract: SEVERAL authors (see refs 1–5 for example) have studied the possible influence of galactic point X-ray sources in the ionospheric D region. The observed variabilities in phase and amplitude of very low frequency (v.l.f.) night-time propagation have been attributed to different ionisation sources, but the relationship between the appearance of strong X-ray sources in the sky and the recorded v.1.f. phase and intensity variations has been emphasised. Particularly important are the effects of Sco X-1, Cen X-2 and Cen X-4.

Das thermische Verhalten von Na5[Fe(CN)5SO3]·2H2O

Abstract: The thermal behaviour of Na5[Fe(CN)5SO3]·2H2O has been investigated by thermogravimetric and differential thermal analysis. Detailed studies of the decomposition residues using various physicochemical methods show that decomposition occurs in a manner similar to that previously postulated for related compounds.