The interaction of streptokinase.plasminogen activator complex, tissue-type plasminogen activator, urokinase and their acylated derivatives with fibrin and cyanogen bromide digest of fibrinogen. Relationship to fibrinolytic potency in vitro.

The effects of purified soluble fibrin and of fibrinogen fragments (fibrin mimic) on the activation of Lys-plasminogen (i.e. plasminogen residues 77-790) to plasmin by streptokinase.plasminogen activator complex and by tissue-type plasminogen activator were studied. Dissociation constants of both activators were estimated to lie in the range 90-160 nM (fibrin) and 16-60 nM (CNBr-cleavage fragments of fibrinogen). The kinetic mechanism for both types of activator comprised non-essential enzyme activation via a Rapid Equilibrium Ordered Bireactant sequence. In order to relate the fibrin affinity of plasminogen activators to their fibrinolytic potency, the rate of lysis of supported human plasma clots formed in the presence of unmodified or active-centre-acylated precursors of plasminogen activators was studied as a function of the concentration of enzyme derivative. The concentrations of unmodified enzyme giving 50% lysis/h in this assay were 0.9, 2.0 and 11.0 nM for tissue-type plasminogen activator, streptokinase.plasmin(ogen) and urokinase respectively. However, the potencies of active-centre-acylated derivatives of these enzymes suggested that acylated-tissue plasminogen activator and streptokinase.plasminogen complexes of comparable hydrolytic stability were of comparable potency. Both types of acyl-enzyme were significantly more potent than acyl-urokinases.     

The anabolic action of intermittent parathyroid hormone on cortical bone depends partly on its ability to induce nitric oxide‐mediated vasorelaxation in BALB/c mice

There is strong evidence that vasodilatory nitric oxide (NO) donors have anabolic effects on bone in humans. Parathyroid hormone (PTH), the only osteoanabolic drug currently approved, is also a vasodilator. We investigated whether the NO synthase inhibitor L‐NAME might alter the effect of PTH on bone by blocking its vasodilatory effect. BALB/c mice received 28 daily injections of PTH[1–34] (80 µg/kg/day) or L‐NAME (30 mg/kg/day), alone or in combination. Hindlimb blood perfusion was measured by laser Doppler imaging. Bone architecture, turnover and mechanical properties in the femur were analysed respectively by micro‐CT, histomorphometry and three‐point bending. PTH increased hindlimb blood flow by >30% within 10 min of injection (P < 0.001). Co‐treatment with L‐NAME blocked the action of PTH on blood flow, whereas L‐NAME alone had no effect. PTH treatment increased femoral cortical bone volume and formation rate by 20% and 110%, respectively (P < 0.001). PTH had no effect on trabecular bone volume in the femoral metaphysis although trabecular thickness and number were increased and decreased by 25%, respectively. Co‐treatment with L‐NAME restricted the PTH‐stimulated increase in cortical bone formation but had no clear‐cut effects in trabecular bone. Co‐treatment with L‐NAME did not affect the mechanical strength in femurs induced by iPTH. These results suggest that NO‐mediated vasorelaxation plays partly a role in the anabolic action of PTH on cortical bone. © 2016 The Authors. Cell Biochemistry and Function published by John Wiley & Sons, Ltd.     

Nuclear gene trees and the phylogenetic relationships of the mangabeys (Primates: Papionini)

Phylogenetic relationships of mangabeys within the Old World monkey tribe Papionini are inferred from analyses of nuclear DNA sequences from five unlinked loci. The following conclusions are strongly supported, based on congruence among trees derived for the five separate gene regions: (1) mangabeys are polyphyletic within the Papionini; (2) Cercocebus is the sister taxon to the genus Mandrillus; and (3) Lophocebus belongs to a clade with Papio and Theropithecus, with Papio as its most likely sister taxon. Morphologically based phylogenies positing mangabey monophyly were evaluated by mapping the sequences for each locus on these trees. The data seem to fit these trees poorly in both maximum-parsimony and likelihood analyses. Incongruence among nuclear gene trees occurred in the interrelationships among Lophocebus, Papio, and Theropithecus. Several factors that may account for this incongruence are discussed, including sampling error, random lineage sorting, and introgression.      

PPCMatrix: a PowerPC dotmatrix program to compare large genomic sequences against protein sequences

Summary : An interactive dotmatrix program for the MacOS was designed that allows comparison of DNA to protein sequences using nested 3-frame translations. Availability : Shareware, available at http://copan.bioz.unibas.ch/software/ Contact : burglin@ubaclu. unibas.ch