5-Hydroxylation of kynurenine in animals

Zusammenfassung 5-Oxykynuramin (Vorläufer von Mausamin aus Maushirn) wurde aus Urin von Huhn und Maus nach Verabreichung von Kynurenin durch Kombination der Ionen-Austausch-Chromatographie mit Papier-Chromatographie isoliert. Durch Vergleich mit dem synthetischen Präparat wurde es papierchromatographisch und durch Spaltung mittels Mäuseleberhomogenat in 4,6-Dioxychinolin und 6-Oxykynurensäure identifiziert.

---

---

The authors thank Dr. K.Murakami for his help in this study.     

Increase of collagen synthesis in pulmonary arteries of monocrotaline-treated rats

Summary Collagen synthesis in the pulmonary artery in animals with pulmonary hypertension was studied using monocrotaline-treated rats as a model. Incorporation of¹⁴C-labeled proline into collagenase-digestible protein in the pulmonary artery was found to be 4–5 times higher in monocrotaline-treated rats than in control rats.     

Leukocyte accumulation promoting fibrin deposition is mediated in vivo by P-selectin on adherent platelets.

The glycoprotein P-selectin is a cell adhesion molecule of stimulated platelets and endothelial cells, which mediates the interaction of these cells with neutrophils and monocytes. It is a membrane component of cell storage granules, and is a member of the selectin family which includes E-selectin and L-selectin. P-selectin recognizes both lineage-specific carbohydrate ligands on monocytes and neutrophils, including the Lewis x antigen, sialic acid, and a protein component. In inflammation and thrombosis, P-selectin may mediate the interaction of leukocytes with platelets bound in the region of tissue injury and with stimulated endothelium. To evaluate the role of P-selectin in platelet-leukocyte adhesion in vivo, the accumulation of leukocytes within an experimental thrombus was explored in an arteriovenous shunt model in baboons. A Dacron graft implanted within an arteriovenous shunt is thrombogenic, accumulating platelets and fibrin within its lumen. These bound platelets express P-selectin. Here we show that antibody inhibition of leukocyte binding to P-selectin expressed on platelets immobilized on the graft blocks leukocyte accumulation and inhibits the deposition of fibrin within the thrombus. These results indicate that P-selectin is an important adhesion molecule on platelets, mediating platelet-leukocyte binding in vivo, that the presence of leukocytes in thrombi is mediated by P-selectin, and that these leukocytes promote fibrin deposition.