A binding site for histamine in hog pyloric mucosa

Zusammenfassung In verschiedenen Lagen der Mucosa und der Submucosa des Pylorusteils des Schweinemagens wurden Mastzellen gezählt und der Histamingehalt berechnet. Der hohe Histamingehalt lässt sich durch die entsprechend hohe Mastzellenzahl erklären. Die Mastzellenzahl fällt in der angrenzenden Mucosa steil ab, doch bleibt der Histamingehalt gleich hoch. Es ist möglich, dass in diesem Gewebe neben den Mastzellen auch das metachromatische Mucin der unteren Mucosa Histamin bindet.     

Observations on vitamin B12-binding factor from hog gastric mucosa

Riassunto Vengono riferiti i risultati dell'esame con elettroforesi continua su carta di una preparazione dalla mucosa gastrica di maiale dotata di potere di legame sulla vitamina B₁₂ e l'isolamento da essa con metodi di estrazione e di precipitazione frazionata del fattore responsabile di tale legame.     

Starvation and gastrin storage in the pyloric antral mucosa of male rabbits

Résumé Parmi les lapins mâles privés de nourriture pendant une période de 72 h au maximum, la quantité de gastrine brutte par gramme fut la plus élevée chez les sujets soumis à ce test pendant 12 h et la moins élevée chez ceux qui l'ont subit pendant 72 h au maximum. L'activité gastrique de l'extrait brut n'était pas affectée par la privation de nourriture et aucune corrélation ne put être établie entre le taux de la glucose sanguine et la gastrine accumulée chez les lapins affamés.

---

---

Acknowledgments. I am grateful to the M. R. C. London for the synthetic human gastrin I used. This work was supported by fund from University of Ibadan Senate Research Grant.     

A possible role for histamine in larval growth

Résumé Le rôle possible de l'histamine au cours de la croissance larvaire a été étudié. L'inhibition de l'oxydase des diamines au moyen de l'aminoguanidine, a fortement ralenti la croissance larvaire duTribolium confusum. Cette substance, cependant, ne s'est pas avérée toxique. D'autre part l'inhibition des décarboxylases par le semicarbazide ou le deoxypyridoxine ne modifie pas la croissance sans devenir toxique.     

Amantadine modulates phencyclidine binding site sensitivity in rat brain

Summary Amantadine, an antiviral drug with various CNS effects, significantly increases the affinity of the [³H] PCP receptor in rat brain. Rimantadine, an analogue of amantadine devoided of CNS effects, does not have any affect on the [³H] PCP receptor. These results may suggest that some of the CNS actions of amantadine are related to an interaction with the PCP receptor.Acknowledgments. We thank Dr W. K. Schmidt (E.I. Dupont, Newark, Delaware) for gifts of amantadine and rimantadine. Dr R. Quirion is a fellow of the Medical Research Council of Canada.     

The site of binding of injected H3-norepinephrine

Zusammenfassung Tritium-markiertes nor-Epinephrin, welches im Meerschweinchenherzen 4 bis 8 h nach intravenöser Injektion gebunden war, wurde mit der gleichen Geschwindigkeit wie körpereigenes Catecholamin nach Verabreichung von Reserpin freigesetzt. Es kann daher angenommen werden, dass injiziertes nor-Epinephrin sich im Herzen mit der Masse des endogenen Hormons vermischt.     

A new histamine metabolite,quantitatively important in chicken

Summary After i.v. injection of¹⁴C-histamine to chicken, we identified one of the histamine metabolites as N-acetylmethylhistamine in the urine. This new metabolite accounted for about 20% of the urinary or 14% of the administered radioactivity.This work was supported by the Agricultural Research Council of Norway (grant No. 14.202.01).Acknowledgment. I wish to thank J. Utne Skåre who performed all the mass-spectrographic work and A. Grande for making the colon fistula.     

High affinity of quinidine for a stereoselective microsomal binding site as determined by a radioreceptor assay

Summary The techniques of the radioreceptor binding assay were applied to detect stereoselective binding of quinidine and quinine to a site on human liver microsomes. Binding of³H-dihydroquinidine was 50% inhibited by 20–100 nM quinidine, while its enantiomer quinine did not displace the³H-ligand at concentrations up to 500 nM. This stereoselectivity agreed with the affinity values measured by functional enzyme assays of cytochrome P450 activity using sparteine or debrisoquine as substrates.Acknowledgments. We thank C. Ulpian for advice and assistance. We also thank Dr M. Robinette of Metro Organ Retrieval and Exchange and Dr T. Inaba for making human hepatic tissue available. This work was supported by grants from the Medical Research Council of Canada.     

Zinc binding to peptide analogs of the structural zinc site in alcohol dehydrogenase: Implications for an entatic state

Zinc binding to the peptide replica and analogs to residues 93–115 of horse liver alcohol dehydrogenase (ADH) was examined by competition of the peptides and the chromophoric chelator 4-(2- pyridylazo)resorcinol for zinc and X-ray absorption fine structure analysis of the zinc ligands. In the enzyme, zinc is coordinated by four Cys residues. In the peptide replica, zinc is bound to three Cys and one His residue. A four-Cys zinc coordination is observed only when His is removed, leading to increased zinc stability. ADH crystal structures reveal that the ε-amino group of the conserved residue Lys323 is within H-bond distance of the backbone amide oxygens of residues 103, 105 and 108, likely stabilizing the zinc coordination in the enzyme. The peptide data thus indicate structural strain and increased energy in the zinc-binding site in the protein, characteristic of an entatic state, implying a functional nature for this zinc site. Received 3 July 2008; received after revision 11 August 2008; accepted 1 September 2008     

Binding site of activators of the cystic fibrosis transmembrane conductance regulator in the nucleotide binding domains

The use of substances that could activate the defective chloride channels of the mutant cystic fibrosis transmembrane conductance regulator (CFTR) has been suggested as possible therapy for cystic fibrosis. Using epithelia formed by cells stably transfected with wildtype or mutant (G551D, G1349D) CFTR, we estimated the apparent dissociation constant, K_D, of a series of CFTR activators by measuring the increase in the apical membrane current. Modification of apparent K_D of CFTR activators by mutations of the nucleotide-binding domains (NBDs) suggests that the binding site might be in these regions. The human NBD structure was predicted by homology with murine NBD1. An NBD1-NBD2 complex was constructed by overlying monomers to a bacterial ABC transporter NBD dimer in the head-to- tail conformation. Binding sites for CFTR activators were predicted by molecular docking. Comparison of theoretical binding free energy estimated in the model to free energy estimated from the apparent dissociation constants, K_D, resulted in a remarkably good correlation coefficient for one of the putative binding sites, located in the interface between NBD1 and NBD2.Received 21 September 2004; received after revision 6 December 2004; accepted 10 December 2004     

A specific binding protein for the moulting hormone ecdysterone in locust haemolymph

Summary Specific binding of³H-ecdysterone to a high mol. wt. protein from Locusta migratoria haemolymph was shown by gel filtration. The hormone-protein complex shos a dissociation constant K_d3.10^–7 M, and the concentration of binding sites varies during the last larval instar.     

Phylogenetical persistence of the non-mast cell histamine stores of the digestive tract: A comparison with mast cell histamine

Résumé La teneur en histamine des divers segments du tube digestif a été mesurée chez les poissons, les batraciens et les reptiles. Les résultats indiquent la présence de dépôts d'histamine dans la muqueuse gastrique de tous les vertébrés, tandis que l'histamine de mastocytes n'existe que chez des groupes limitées de vertébrés.