Showing papers by "Université catholique de Louvain published in 1971"
TL;DR: A comparison of the amino acid compositions of human lactoferrin and transferrin suggests that the two proteins are more closely related to one another than was suspected before.
Abstract: A molecular weight of 75000 was computed for human lactoferrin on the basis of a sedimentation coefficient s°20, W= 4.93, a partial specific volume v20= 0.715 and a diffusion coefficient D°20, W= 5.6×10−7 cm2xsec−1. A molecular weight of 76800 ± 1600 was estimated from electrophoreses in agarose acrylamide gel containing sodium dodecylsulphate. No decrease of the molecular weight was observed when the reduced and alkylated or aminoethylated protein was submitted to 6 M urea, indicating that the molecule of lactoferrin consists of a single polypeptide chain. From the analysis of the amino acid composition of human lactoferrin a theoretical molecular weight of 76400 was computed by means of a statistical test. A comparison of the amino acid compositions of human lactoferrin and transferrin suggests that the two proteins are more closely related to one another than was suspected before.
185 citations
TL;DR: In this article, the activation of synthetase in a liver gel filtrate and the latency by which it is normally preceded have been studied in conditions where the level of phosphorylase a was greatly modified by the addition of either the pure enzyme or of antibodies directed against it.
Abstract: The activation of glycogen synthetase in a liver gel filtrate and the latency by which it is normally preceded have been studied in conditions where the level of phosphorylase a was greatly modified by the addition of either the pure enzyme or of antibodies directed against it. In the presence of liver or muscle phorphorylase a, glycogen synthetase phosphatase was nearly inactive; phosphorylase b had only a slight effect. Antibodies, obtained in the rabbit against dog liver phosphorylase, strongly depressed the activity of phosphorylase a in a mouse liver preparation; they simultaneously allowed an immediated activation of glycogen synthetase.
These results indicate that the lag period that precedes that activation of glycogen synthetase in a liver filtrate is the time required for the conversion of phosphorylase a into b by phosphorylase phosphatase. The previously reported shortening of the lag period by glucose, caffeine and nicotinamide or by a tratment with glucocorticoids is entirely explained by the faster inactivation of phosphorylase in the same conditions. The elongation of the lag period by glycogen and its supporession by AMP and magnesium remained however to be explained. It has been shown that the dose of glycogen that prolongs the lag period also inhibits phosphorylase posphatase, wherease AMP and magnesium counteract the inhibition of synthetase phosphatase by phosphorylase a.
150 citations
TL;DR: The renal effect of insulin is demonstrated with plasma hormone concentration observable in pathophysiological conditions; it offers therefore a possible explanation for some clinical findings such as the changes in sodium, potassium and water excretion occurring in man after fasting and subsequent glucose feeding.
Abstract: Insulin has been shown to decrease sodium, potassium and water excretion by direct action on the kidney. Reduction of sodium excretion is due to enhanced tubular reabsorption as a probable consequence of stimulated active sodium transport. The renal effect of insulin is demonstrated with plasma hormone concentration observable in pathophysiological conditions; it offers therefore a possible explanation for some clinical findings such as the changes in sodium, potassium and water excretion occurring in man after fasting and subsequent glucose feeding.
127 citations
TL;DR: In this paper, a concerted cycloaddition involving an orthogonal approach of the ketene and olefin in accordance with Woodward and Hoffmann's suggestion was proposed.
122 citations
105 citations
TL;DR: The ribosome load of the microsomal vesicles increased steadily along the density gradient, indicating the existence of a continuous spectrum of microsome entities ranging from entirely ribosomal-free vesicle to vesicular heavily coated with ribosomes.
Abstract: Rat liver microsomes and microsomal subfractions isolated by density equilibration were submitted to a quantitative morphological and biochemical analysis. The total area of the endoplasmic reticulum was estimated at 7.3 m2 per g of liver. The microsome fraction contained 2.8 mg of phospholipids and 6.7 mg of proteins per m2 of membrane area. After correction for ribosomal and intracisternal proteins, the latter value was lowered to 4.7 mg of membrane protein per m2. More than half of the microsomal vesicles carried ribosomes. After density equilibration of the microsomes, the distribution pattern of ribosomes followed closely that of RNA. The ribosome load of the microsomal vesicles increased steadily along the density gradient, indicating the existence of a continuous spectrum of microsomal entities ranging from entirely ribosome-free vesicles to vesicles heavily coated with ribosomes.
103 citations
TL;DR: The first appeals to Medvedev's delayed maturity hypothesis of ageing and the second one links developmental speed to mitotic division rate, which are put forward to explain those data.
78 citations
62 citations
60 citations
TL;DR: In this article, first principles dynamical calculations are presented for the diffraction of low energy electrons at clean copper (100) surface under normal incidence, and the results are carefully compared to the experimental data of Andersson in a wide energy range from 0 to 140 e V and for the three main diffracted beams.
52 citations
TL;DR: Late circulatory disturbances of the lungs, brain, liver and skin and late modifications of the respiratory and hepatic functions after local x-irradiation, are assessed by appropriate quantitative in vivo radiotracer tests in rats.
Abstract: SummaryLate circulatory disturbances of the lungs, brain, liver and skin and late modifications of the respiratory and hepatic functions after local x-irradiation, are assessed by appropriate quantitative in vivo radiotracer tests in rats.Except for the central nervous system, which shows an increase of its blood flow, a decrease of the organic functions and their circulatory supply is observed. These late changes become statistically demonstrable above a dose-level of 1000 R.
TL;DR: It is concluded that longevity is not determined solely by preimaginal duration of development and that more of one developmental factor must be involved.
TL;DR: La mesure toutes les 3, 6, 12 ou 24 h, sous deux photopériodicités distinctes, de the ponte journalière de Drosophila melanogaster a montré that la ponte présente un cycle journalier bien marqué and que celui-ci peut-être modifié par un changement de the photopÉriodicity.
Abstract: La mesure toutes les 3, 6, 12 ou 24 h, sous deux photoperiodicites distinctes, de la ponte journaliere deDrosophila melanogaster a montre que la ponte presente un cycle journalier bien marque et que celui-ci peut-etre modifie par un changement de la photoperiodicite.
TL;DR: In this article, a grand nombre de transitions, appartenant aux substitutions isotopiques D12C16O16OD, H12C 16O 16OD, D12 C16O 16 OD, H 12C 16 O 16 OD and H 13C 16 OD of the molecule d'acide formique, ont ete mesurees Une determination des constantes de rotation de ces differentes molecules est donnee.
TL;DR: In this article, a general framework for thinking in which various problems related to buyer behaviour are recognized is proposed, and two comprehensive consumer behaviour models briefly, and after a more thorough examination retains a third as a consumer behaviour framework.
Abstract: Proposes a general framework for thinking in which various problems related to buyer behaviour are recognized. Examines how the marketing concept has developed this century. Reviews two comprehensive consumer behaviour models briefly, and after a more thorough examination retains a third as a consumer behaviour framework. Attempts to indicate the present situation with regard to consumer behaviour.
TL;DR: Horseradish peroxidase has been used as a cytochemical tracer to study peculiar ultra-structural aspects of exogenous protein uptake and fate in four types of rat liver cells to describe the localization of HRP in cytoplasmic annular profiles and intercellular spaces.
TL;DR: The sedimentation and diffusion coefficients of undissociated haemocyanins from Helix pomatia, Archachatina marginata, Pila leopoldvillensis and Murex trunculus have been determined by ultracentrifugation and laser spectroscopy.
Abstract: 1. 1. The sedimentation and diffusion coefficients of undissociated haemocyanins from Helix pomatia, Archachatina marginata, Pila leopoldvillensis and Murex trunculus have been determined by ultracentrifugation and laser spectroscopy. 2. 2. The s 20.w 0 values were all a little over 100 S, and the D 20.w 0 values were all a little over 1·0 × 10 −7 cm 2 sec −1 . 3. 3. Combination of these values with determined or calculated values υ , the partial specific volume, gave molecular weights of close to 9 × 106 for all these haemocyanins.
TL;DR: In this article, an etude approfondie du spectre de rotation of l'etat fondamental de vibration de l'acide formique a ete entreprise.
TL;DR: Just how much importance attaches to the humic matter, not only as an energy substrate reserve for the micro-organisms and plants but also as a site for biological activities which are quite distinct from any microbial proliferation and the role of which in plants has still to be studied.
Abstract: The dialysed humic acids obtained from a forest Mull by extraction of a diluted solution of sodium carbonate are enzymatically active. It is found by radiorespirometry that the humic acids act on thel-tryptophan carboxyl C14, although thed-tryptophan carboxyl suffers no attack. The methylene group and the indole and benzene nuclei are not broken down. Only the carboxyl function is mineralised. Radiochromatography shows that through the action of the humic acids the tryptophan is broken down primarily into indoleacetamide and secondarily into β-indoleacetic acid. From the nature of these compounds it is assumed that the humic acids have an oxygenas effect on thel-tryptophan. The enzymatic activity has its optimum value at 65°C. It is partially inhibited by lyophilisation and by toluene. The pyridoxal phosphate (0.1 µM) has a slight activating influence. The alkalis and mineral acids decompose the enzyme. We can therefore see just how much importance attaches to the humic matter, not only as an energy substrate reserve for the micro-organisms and plants but also as a site for biological activities which are quite distinct from any microbial proliferation and the role of which in plants has still to be studied. It would be of interest to determine the presence of this enzymatic system in other pedologically defined soils and to study it in correlation with their fertility. In addition, there remains the task of detecting the microbial agents in the soil which contribute to the formation of this remarkable enzymatic system.
TL;DR: The interferometric method proposed here obviates the limitations of previous methods, its accuracy is better than 1 nm and it is restricted to special cases.
Abstract: In quantitative electron microscopy, a knowledge of the thickness (0) of the sections is often required . For example, when objects smaller than 0 (e .g . ribosomes) are counted in sections, 0 must be known in order that the observed numbers may be related to the unit volume of the section . Even when comparatively large structures are submitted to morphometric analysis, the section thickness cannot be disregarded if the size of the object is of the order of a few times 0 (5) . Several techniques have been used to measure section thickness, but they suffer important limitations, which can be of three kinds : (a) Their accuracy is not satisfactory, at least for 0 ranging from 30 to 60 nm. In published interferometric methods, the accuracy is not better than 10% (2, 7). (b) Thickness measurement and electron microscopic examination cannot be performed on the same section, mounted on the usual microscopy grids (6) . (c) The method is restricted to special cases, for example when certain folds are present in the section (4) or when standard objects are embedded together with the material (3) . The interferometric method proposed here obviates the limitations (b) and (c) and its accuracy is better than 1 nm . We used a Zeiss Standard GFL POL microscope, equipped with a Jamin-Lebedeff
TL;DR: In this article, the slow thermolysis of ammonium dichromate crystals is studied by means of differential thermal analysis and thermogravimetric analysis and four consecutive reactions clearly occur.