Showing papers by "Paul Sabatier University published in 1973"
139 citations
TL;DR: In the adult carp, the ultrastructure of the enterocytes of the distal segment of the medium intestine is similar to that of the intestinal cells of certain mammals during the neonatal period as discussed by the authors.
Abstract: In the adult carp, the ultrastructure of the enterocytes of the distal segment of the medium intestine is similar to that of the intestinal cells of certain mammals during the neonatal period. Frequent aspects of pinocytosis are visible at the base of a plateau of already developed microvillosities. The apical cytoplasm shows the presence of a dense tubulo-vesicular network. The vacuoles which separate off run together to form a voluminous supranuclear body. Their P.A.S. positive and orthochromatic contents are rich in alkaline phosphatases. The permeability of this epithelium to macromolecules is demonstrated by the administration of “Horseradish Peroxidase” (HRP). This protein penetrates by pinocytosis into the apical tubulo-vesicular system and reaches the blood circulation via the extra-cellular spaces. The presence of certain structures involved in protein transport following a period of experimental fasting of six months reflects their independence with regard to exogenous supplies.
70 citations
TL;DR: The chemisorption of oxygen on the copper faces (110, (100) and (111) has been studied by LEED as discussed by the authors, and a final adsorption compound is evident on these three faces.
44 citations
TL;DR: In this article, the synthesis and chemical reactivity of 1-sila- and 1-germa-3-cyclopentenes (I), 6-oxa-3sila and -3-germabicyclo[3.1.0]hexanes (II) are closely dependent upon the heteroatom M and its Σ substituents.
41 citations
TL;DR: In this paper, a planification de l'echantillonnage is envisagee dans le cas d'inventaires faunistiques extensifs and d'etudes quantitative intensives.
Abstract: La planification de l'echantillonnage est envisagee dans le cas d'inventaires faunistiques extensifs et d'etudes quantitatives intensives. Des methodes sont donnees pour decrire un echantillon en termes statistiques. La dispersion spatiale d'une population est discutee et les types fondamentaux de distribution decrits. Des tests sont presentes pour definir la dispersion au hasard, reguliere ou contagieuse d'une population. Les problemes d'estimation des nombres par unite de surface ou de volume sont exposes, ainsi que les methodes de calcul des limites de confiance de ces estimations. Les methodes parametriques et non-parametriques de comparaison quantitative de deux echantillons sont decrites et les utilisations du x2 et des tables de contingence discutees. Une derniere partie est consacree aux problemes poses par l'echantillonnage sur le terrain et le sous-echantillonnage au laboratoire.
41 citations
TL;DR: In this article, the photoelectron spectra of allylgermanes and allylstannanes were investigated and the hyperconjugative ability of the CM(M = Si, C, Ge and Sn) bonding MO's with the ethylene π-MO is explained by simple perturbation theory.
39 citations
TL;DR: A direct role of 25‐OH D3 in the regulation of calcium metabolism may have to be considered in patients with chronic renal failure, since these patients may be unable to synthesize 1,25 dihydroxy D3, the metabolite of vitamin D3 considered to be active on intestine and bone.
Abstract: . 47 patients with chronic renal failure were investigated for plasma 25-hydroxycholecalciferol (25-OH D3) concentration, serum calcium, phosphorus, alkaline phosphatase. 22 patients had chronic haemodialysis twice weekly. There is a highly significant positive coefficient of correlation between calcaemia and 25-OH D3 plasma concentration. Levels of serum calcium had previously been shown to correlate well with the presence and type of osteodystrophies in chronic renal failure. Since these patients may be unable to synthesize 1,25 dihydroxy D3, the metabolite of vitamin D3 considered to be active on intestine and bone, a direct role of 25-OH D3 in the regulation of calcium metabolism may have to be considered.
39 citations
TL;DR: In this paper, the depolarization thermocurrent (DTC) method was used to study mechanisms described by the Williams-Landel-Ferry (WLF) equation.
Abstract: The depolarization thermocurrent (DTC) method gives the dependence of the dielectric relaxation time on temperature. It has been used for investigations of relaxations obeying an Arrhenius-like law in crystalline polymers. The analysis of this method shows it is possible to study mechanisms described by the Williams-Landel-Ferry (WLF) equation. The critical temperature appearing in the free-volume theory of Cohen and Turnbull and also in the statistical thermodynamic theory of Adam and Gibbs can then be measured with good accuracy. The thermal coefficient of expansion of the free-volume and the WLF coefficient for any reference temperature can also be obtained. Since analysis of the experimental DTC spectrum is particularly simple, this method seems to be a very useful tool for examination of relaxation transitions in amorphous polymers. As an example, results obtained for poly(methyl methacrylate) are presented; they are consistent with published data.
34 citations
TL;DR: The NMR spectra of these products showed that both were formed as a mixture of cis and trans isomers, with the isomer ratios being very similar to those of the starting silacyclobutane as mentioned in this paper.
32 citations
TL;DR: In this article, the theoretical energy minimum for the (60, 60, 60) -so-called LEM -conformation in which each methyl group is staggered with respect to the two opposite (MC) bonds is derived.
24 citations
TL;DR: In this article, the steric requirement for the toxic activity of cord factor was studied by synthesizing several stereoisomers of methyl 6-mycoloyl-α-D-glucopyranoside and determining their toxicity for mice and the action on the mitochondrial oxidative phosphorylation.
TL;DR: Genetic studies of the fate of recombinants as well as the measure of the amount of DNA taken up have shown that all the markers are integrated in strain 401 by the same recombination process, that specific to high efficiency markers.
Abstract: Transformation of the pneumococcus mutant 401 by DNA9s bearing the standard reference marker and several other markers belonging to two unlinked loci has shown that differences in the integration efficiencies of these markers were considerably reduced in this strain compared to the wild-type strain Cl 3 . The sensitivities of mutant 401 to ultraviolet light and to X-ray irradiation are the same as those of Cl 3 . However, in 401 all the markers tested are more resistant to inactivation as shown by transformation of 401 and Cl 3 by ultraviolet-irradiated DNA. The increase in resistance is greater for low efficiency (LE) markers than for high efficiency (HE) markers.—The decreased discrimination between LE and HE markers in strain 401 is not due to a mechanism related to modification of markers in the transforming DNA by the recipient cells, nor are the proteins inducing competence of the cells responsible for the differences in the integration efficiencies of various markers.—Genetic studies of the fate of recombinants as well as the measure of the amount of DNA taken up have shown that all the markers are integrated in strain 401 by the same recombination process, that specific to high efficiency markers.
TL;DR: Une population de Sialis lutaria a ete etudiee de 1969 a 1971 dans le lac de Port-Bielh (2 285 m, Pyrenees-Centrales) dans l'isothermie d'automne, where dix stades larvaires ont ete denombres.
Abstract: Une population de Sialis lutaria a ete etudiee de 1969 a 1971 dans le lac de Port-Bielh (2 285 m, Pyrenees-Centrales). Dix stades larvaires ont ete denombres. Le cycle de developpement dure trois annees. Les larves se nourrissent essentiellement de crustaces benthiques pendant la premiere annee, de chironomides et d'oligochetes les annees suivantes. La croissance larvaire s'effectue pendant l'isothermie d'automne. 66,7 % de l'accroissement intervient au cours de la troisieme annee. Le rapport PS/PF varie au cours de la croissance. La production annuelle nette atteint 5,12 kg/ha/PS. Elle represente les 2/3 de celle du chironomide dominant du lac. Le rapport P/B max = 1,34 montre une certaine stabilite; il est voisin de ceux precedemment trouves pour deux chironomides du meme lac.
TL;DR: Results obtained during the purification of oak leaves suggest the presence, in oak, of two isofunctional forms of the enzyme, the one sensitive, the other insensitive to the action of aromatic amino acids.
Abstract: Chorismate mutase from Quercus pedunculata Ehrh leaves has been purified by ammonium sulfate precipitation, molecular sieving and hydroxyapatite chromatography Some results obtained during the purification suggest the presence, in oak, of two isofunctional forms of the enzyme, the one sensitive, the other insensitive to the action of aromatic amino acids The regulable form exhibits a molecular weight of about 45,000 It is inhibited by tyrosine and by phenylalanine and is activated by tryptophan In addition to its activating properties, this latter compound, endowed with a great affinity for the enzyme, reverses the inhibition due to the two other amino acids
The H+ concentration of the medium plays an important role in the sensitivity of the enzyme with regard to its effectors Inhibition by tyrosine and by phenylalanine is maximal at pH 65, at which value the two ligands present an identical effect At alkaline pH values, the rate of inhibition decreases regularly, tyrosine becoming the most effective inhibitor Activation by tryptophan is particularly acute in a mildly acid medium; at pH 65, this effector increases the enzymatic activity threefold Its action is weak (20% activation) in the optimum pH zone (pH 78) and increases towards the more basic pH values As a result, tryptophan maintains a constant level of enzymatic activity throughout a large pH zone (between 65 and pH 90) The physiological significance of these results is discussed
TL;DR: In this paper, a new approach to the acylphosphines R 2 CH-CO-PEt 2 was proposed, which is a new method of synthesis of the phosphorylated β-diketone.
TL;DR: Histology shows that a part of their outer wall consists of a particular epithelium covered by a cuticular intima, which is thicker than the intima of the common epithelia, which are associated with mitochondria.
Abstract: Les Machilides presentent une serie de vesicules abdominales paires, sous forme de sacs exsertiles capables d'absorber l'eau d'un film liquide. Les coupes histologiques montrent qu'une partie de la paroi de ces vesicules est faite d'un epithelium particulier revetu d'une intima cuticulaire plus epaisse que celle de l'epithelium banal. La microscopie electronique permet de preciser la structure des cellules absorbantes qui sont caracterises essentiellement par des microvillosites apicales et de profondes invaginations de la membrane plasmique basale associees a des mitochondries allongees. Une comparison est faite avec d'autres types de cellules absorbantes connues chez les Arthropodes, notamment dans le rectum. Grâce a leurs vesicules abdominales, les Thysanoures possedent des organes originaux jouant un role important dans l'equilibre hydrique de ces insectes.
TL;DR: In this paper, the germyl and silylphosphines R 3 MPEt 2 (M = Ge, Si) condense by a dipolar 1,2-addition to one of the carbonyl groups of the α-diketones and lead to phosphorus ketoalcoxygermanes or -silanes.
TL;DR: Most of the mutants found are transformation-defective and show a large diversity in their response to ultraviolet light, and some of these mutants have lost their ability to take up transforming DNA.
Abstract: A method of transformation on solid medium especially adapted for pneumococcus has been developed. Under specific conditions, all colonies that are allowed to grow in the presence of transforming DNA for six hours give rise to transformed bacteria. Combined with replica plating this technique has been used to isolate mutants modified with regard to recombination. Most of the mutants found are transformation-defective and show a large diversity in their response to ultraviolet light. Some of these mutants have lost their ability to take up transforming DNA. One shows a reduced yield of transformants for a given quantity of DNA taken up. Mutants that manifest altered behavior with regard to marker efficiencies have also been isolated. One of these exhibits a decrease in the transformation efficiency of only the high efficiency markers and two mutants show a decrease in the transformation efficiency of the low efficiency markers.
TL;DR: Lithium reacts rapidly with 1,2-dichloro-disilanes, digermanes and conjugated dienes in a solvent of Et2O/THF(5/1) to give 1, 2-disila-, and 1 2-digerma-4-cyclohexenes in good yield as discussed by the authors.
TL;DR: The importance of algales benthiques dans la productivite primaire d'un lac de haute montagne is evaluated in this article, where Nitella flexilis constitue 80 % de la biomasse algale benthique; les variations de sa teneur en Chlorophylle traduisent une adaptation aux modifications du climat lumineux qu'elle determine en partie.
Abstract: L'importance des communautes algales benthiques dans la productivite primaire d'un lac de haute montagne est evaluee. Les algues lithophytiques de la zone littorale (0-6 m) et Nitella flexilis, qui recouvre pratiquement tout le fond de la zone littori-profonde (6-19 m), forment une biomasse environ 140 fois superieure a la biomasse moyenne de phytoplancton pendant la periode estivale. Nitella flexilis constitue 80 % de la biomasse algale benthique; les variations de sa teneur en Chlorophylle traduisent une adaptation aux modifications du climat lumineux qu'elle determine en partie. La colonisation de substrats artificiels s'avere peu adequate pour evaluer la production du periphyton; elle indique cependant une productivite 10 fois moindre en zone littorale qu'en zone littori-profonde. Les mesures, au 14 C, du taux d'assimilation de Nitella flexilis et des algues epiphytes revelent qu'a la suite de phenomenes de compensation par le developpement du periphyton et l'ajustement de la teneur en Chlorophylle, l'activite photosynthetique depend peu de la lumiere. La contribution des algues benthiques a la production primaire est evaluee a 30 %. Leur role dans le cycle des elements chimiques est envisage.
TL;DR: In this paper, the depolarization thermocurrent (DTC) method was used to resolve the dielectric relaxation spectrum in polyglycine I and II between liquid nitrogen temperature and 150°C.
Abstract: The depolarization thermocurrent (DTC) method was used to resolve the dielectric relaxation spectrum in polyglycine I and II between liquid nitrogen temperature and 150°C. The results are compared with those obtained by other dielectric methods. In the two forms of polyglycine, the same relaxation has been observed at very low temperatures. At higher temperatures an influence of moisture on the mechanisms has been observed; a relaxation existing in ice is noticed also in dry polyglycine I. Relaxations studied by DTC near or above room temperature, seem to be related with measured de conductivity and give information concerning the nature of charge carriers.
La methode des thermocourants de depolarisation (TCD) a permis la resolution du spectre des relaxations dielectriques dans la polyglycine I et II entre la temperature de l'azote liquide et 150°C. Les resultats ont ete compares a ceux obtenus par d'autres mesures dielectrques. Dans les deux formes de polyglycine, une měme relaxation a ete observee a tres basse temperature. A plus haute temperature, nous avons montre l'influence de traces d'humidite sur certains mecanismes et avons note la presence dans la polyglycine I deshydratee, d'une relaxation qui aussi dans la glace. Parmi les processus etudies par TCD au vosinage de la temperature ambiante et au-dessus, certains semblent lies a la conductivite mesuree en courant continu: leur etude est sucesptibelde de fournir des informations sur la nature des porteurs de charge.
TL;DR: In this article, the photolysis of trigermanes (PhX 2 GeGe(X)(Ph)GeX 2 Ph (X = Cl or MeO) by α-elimination, and condensation with dimethylbutadiene with formation of germylgermacyclopentenes.
TL;DR: In this article, the optimized geometries and theoretical data from conformational analysis cf borazane and its perfluoro derivatives are investigated within the framework of the CNDO/2 approximation.
TL;DR: In this article, the IR and Raman spectra of four 1-oxa-2-germacyclopentanes, four 1 -oxa -2-germanium derivatives, two monoalkoxytriethylgermaniums, three dialkoxydiethyl germaniums and hexaethyldigermoxane have been examined in the 3600-100 cm −1 region.
TL;DR: In this paper, the Esro S46/2 Skylark was launched into an auroral westward-traveling surge, and data showed that the low-energy (E ≲, 5 kev) electron precipitation remains relatively stable throughout the flight.
Abstract: Twelve auroral electron detectors from 300 ev to 30 kev were launched on the Esro S46/2 Skylark rocket from Kiruna, Sweden, on January 28, 1971, at 2120 MLT into an auroral westward-traveling surge. Data show that the low-energy (E ≲, 5 kev) electron precipitation remains relatively stable throughout the flight; it does not seem to be directly related to the luminous intensity. On the other hand, when the rocket goes through the surge, the high-energy (E ≳ 5 kev) precipitation is greatly increased, and the angular distribution of these electrons, which was anisotropic, being maximum at 90° pitch angle, becomes isotropic. The precipitation mechanism of these electrons in the evening sector during the expansion phase of the magnetospheric substorm is probably associated with instabilities occurring near the equatorial plane in this sector.
TL;DR: In polar solvents, phenylchlorohydrogermanes can add onto the carbonyl group of aldehydes and ketones with formation of α-chlorogermyl alcohols as mentioned in this paper.
TL;DR: In this article, a technique d'attenuation hyperfrequence is used to caracterise dans le silicium a basse temperature, un processus intrinseque de recombinaison regi par une cinetique de second ordre.
TL;DR: The main features of the mass spectra of silacyclopentanol derivatives are hydrogen transfer, hydroxyl α-elimination and expulsion of C(2) and C(4) carbons with their substituents.
TL;DR: In this paper, the dipole moments of trialkylalkoxysilanes, trialkyldisiloxanes and trialkynoxysilicenes have been determined.
TL;DR: It is shown that in vitro optimum temperature is 25°C for the fish, and not 30°C as in Mammalians, and it has been impossible, under the same experimental conditions, to observe normal release of inorganic phosphorus from G-1-P with carp liver.
Abstract: In this paper we give some values of glycogen phosphorylase activity of heart, red muscle and white muscle from the Carp. We show that in vitro optimum temperature is 25°C for the fish, and not 30°C as in Mammalians. We also made measurements with rat and tench liver, but it has been impossible, under the same experimental conditions, to observe normal release of inorganic phosphorus from G-1-P with carp liver.