Purine and pyrimidine receptors

Adenosine 5′-triphosphate (ATP), in addition to its intracellular roles, acts as an extracellular signalling molecule via a rich array of receptors, which have been cloned and characterised. P1 receptors are selective for adenosine, a breakdown product of ATP, produced after degradation by ectonucleotidases. Four subtypes have been identified, A₁, A_2A, A_2B and A₃ receptors. P2 receptors are activated by purines and some subtypes also by pyrimidines. P2X receptors are ligand-gated ion channel receptors and seven subunits have been identified, which form both homomultimers and heteromultimers. P2Y receptors are G protein-coupled receptors, and eight subtypes have been cloned and characterised to date. Received 22 November 2006; received after revision 11 January 2007; accepted 27 February 2007     

Serum cholesterol levels in germ-free chickens

Résumé On démontre qu'il n'y a pas de différence entre le cholestérol du sérum de poulets élevés dans des conditions aseptiques et ceux élevés dans des conditions normales et soumis à un régime sans cholestérol. Les poulets sans bactéries croissent mieux que les poulets normaux.      

Glycerol permeability of erythrocytes

Zusammenfassung Untersuchungen über die Unterschiede in der Lipoidzusammensetzung der Erythrocyten von neun Tierarten ergaben eine verschiedene Glyzerinpermeabilität dieser Zellen. Bei der einen Gruppe zeigen die Erythrocyten eine stark temperatur bedingte Glyzerinpermeabilität, bei der anderen eine hohe, kaum temperaturabhängige Permeabilität, die bei Erniedrigung des pH-Wertes im Medium stark abnimmt.     

The specificity of histones in nucleated erythrocytes

Riassunto Dagli eritrociti del pollo, dellaRana cateasbeiana e del pesceCaranx hippos sono stati isolati gli istoni nella ipotesi che gli eritrociti forniti di nucleo contengano una frazione di istone funzionante come repressore permanente della sintesi degli acidi nucleici. Detti istoni sono stati frazionati ed analizzati nella loro composizione in amino-acidi. In tutte e tre le speci su menzionate è stata trovata una frazione relativamente ricca in lisina, arginina, alanina, e serina che è stata denominata F2c. L'assenza di detta frazione negli altri tessuti incluso il midollo osseo indica che la frazione F2c può costituire un repressore genetico permanente.

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This investigation was supported by the U.S. Public HEalth Service Grant No. CA-07746, American Cancer Society Grants E-388 and IN-43-F2, and by the Robert A. Welch Foundation Grant G-138.     

Pargyline: A glucuronyl transferase inducer

Zusammenfassung Nachweis, dass mehrtägige Behandlung von Ratten mit hohen Dosen Pargylin die Glucuronyltransferase-Aktivität der Lebermikrosomen erhöht.

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This study was supported by U.S. Public Health Service Grant No. NB 02928.

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The authors wish to thank Mr.K. Kingsbury for excellent technical assistance in this study.     

The specificity of histones in chicken erythrocytes

Zusammenfassung Isolierung, qualitative und quantitative Charakterisierung der Histone von Hühnererythrocyten wird beschrieben. Mittels Gelfiltration an Sephadex G 75 wurde eine Fraktion des Histons, charakteristisch für die Hühnererythrocytenzellkerne isoliert und analysiert. Diese Fraktion, als F2c bezeichnet, ist ein Teil des lysinreichen Histons F2, reich an Lysin, Alanin, Serin und Arginin (z.B. 21,0, 15,1, 11,9 und 10,6% respektive). Threonin konnte als N-terminale Aminosäure in dieser Fraktion festgestellt werden.     

Purine nucleotide cycle as a possible anaplerotic process in rat skeletal muscle

Summary The intermediates of the purine nucleotide cycle (PNC) stimulated pyruvate oxidation by isolated skeletal muscle mitochondria in a system containing mitochondria and cytosol from rat skeletal muscle. Thus, in skeletal muscle the PNC might be involved in the anaplerotic supply of tricarboxylic acid cycle intermediates.Acknowledgment. This work was supported by a grant from the Polish Academy of Science within the project MR II.1.2.4.     

Hormonal influences on erythrocyte catechol-O-methyl transferase activity in humans

Résumé Dans le cas de beaucoup de femmes prenant des contraceptifs oraux, l'activité du transférase catéchole-O-méthyle du globule rouge est réduite à des nivaux analogues à ceux observes dans le cas de femmes souffrant de dépression non-traitée. Le dépôt de contraceptifs à action durable n'affecte pas d'une manière significative l'enzyme, bien qu'elle soit réduite pendant le troisième trimestre de la grossesse.     

Excess dietary lysine induces hypercholesterolemia in chickens

Summary Lysine and arginine supplements were fed to 5-day-old chicks to test whether they would develop hypercholesterolemia in response to excess lysine in a fashion similar to mammals. Chicks developed hypercholesterolemia with a 4–5% lysine but not with arginine supplementation. These results indicate the lysine induced hypercholesterolemia is not due to anaplerotic interactions of arginine and lysine with the urea cycle.Acknowledgment. This work was funded in part through a fellowship (D.L.) from the American Heart Association, Illinois affiliate and a grant from the National Livestock and Meat Board.     

Excess dietary lysine induces hypercholesterolemia in chickens

Lysine and arginine supplements were fed to 5-day-old chicks to test whether they would develop hypercholesterolemia in response to excess lysine in a fashion similar to mammals. Chicks developed hypercholesterolemia with a 4-5% lysine but not with arginine supplementation. These results indicate the lysine induced hypercholesterolemia is not due to anaplerotic interactions of arginine and lysine with the urea cycle.     

Interaction of lead with erythrocytes

Zusammenfassung Untersuchungen mit²⁰³Pb in vitro ergeben, dass Blei in den Erythrozyten vorwiegend an Hämoglobin gebunden wird, während Stromasubstanzen kein Blei aufnehmen.