Anticoagulation With an Inhibitor of Factors XIa and XIIa During Cardiopulmonary Bypass.

BACKGROUND: Exposure of blood to polyanionic artificial surfaces, for example, during cardiopulmonary bypass (CPB), induces a highly procoagulant condition requiring strong anticoagulation. Unfractionated heparin (UFH) is currently used during CPB but can lead to serious bleeding complications or development of a hypercoagulable state culminating in life-threatening thrombosis, highlighting the need for safer antithrombotics. Ixodes ricinus contact phase inhibitor (Ir-CPI) is a protein expressed by I. ricinus ticks, which specifically inhibits both factors XIIa and XIa, 2 factors contributing to thrombotic disease while playing a limited role in hemostasis. OBJECTIVES: This study assessed the antithrombotic activity of Ir-CPI in animal contact phase-initiated thrombosis models, including CPB. The safety of Ir-CPI also was evaluated. METHODS: The authors evaluated the antithrombotic activity of Ir-CPI by using in vitro catheter-induced clotting assays and rabbit experimental models of catheter occlusion and arteriovenous shunt. During CPB with cardiac surgery in sheep, the clinical applicability of Ir-CPI was investigated and its efficacy compared to that of UFH using an uncoated system suitable for adult therapy. Taking advantage of the similar hemostatic properties of pigs and humans, the authors performed pig liver bleeding assays to evaluate the safety of Ir-CPI. RESULTS: Ir-CPI prevented clotting in catheter and arteriovenous shunt rabbit models. During CPB, Ir-CPI was as efficient as UFH in preventing clot formation within the extracorporeal circuit and maintained physiological parameters during and post-surgery. Unlike UFH, Ir-CPI did not promote bleeding. CONCLUSIONS: Preclinical animal models used in this study showed that Ir-CPI is an effective and safe antithrombotic agent that provides a clinically relevant approach to thrombosis prevention in bypass systems, including highly thrombogenic CPB.

NDS27 combines the effect of curcumin lysinate and hydroxypropyl-ß-cyclodextrin to inhibit equine PKCδ and NADPH oxidase involved in the oxidative burst of neutrophils.

Polymorphonuclear neutrophils (PMNs) are involved in host defence against infections by the production of reactive oxygen species (ROS), but excessive PMN stimulation is associated with the development of inflammatory diseases. After appropriate stimuli, protein kinase C (PKC) triggers the assembly of NADPH oxidase (Nox2) which produces superoxide anion (O2 (•) (-)), from which ROS derive. The therapeutic use of polyphenols is proposed to lower ROS production by limiting Nox2 and PKC activities. The purpose of this study was to compare the antioxidant effect of NDS27 and NDS28, two water-soluble forms of curcumin lysinate respectively complexed with hydroxypropyl-ß-cyclodextrin (HPßCD) and γ-cyclodextrin (γ-CD), on the activity of Nox2 and PKCδ, involved in the Nox2 activation pathway. Our results, showed that NDS27 is the best inhibitor for Nox2 and PKCδ. This was illustrated by the combined effect of HPßCD and curcumin lysinate: HPßCD, but not γ-CD, improved the release of curcumin lysinate and its exchange against lipid or cholesterol as demonstrated by the lipid colouration with Oil Red O, the extraction of radical lipophilic probes recorded by ESR and the HPLC measurements of curcumin. HPßCD not only solubilised and transported curcumin, but also indirectly enhanced its action on both PKC and Nox2 activities. The modulatory effect of NDS27 on the Nox2 activation pathway of neutrophils may open therapeutic perspectives for the control of pathologies with excessive inflammatory reactions.

Effect of different kinds of anoxia/reoxygenation on the mitochondrial function and the free radicals production of cultured primary equine skeletal myoblasts.

Horses are outstanding athletes, performing in many different disciplines involving different kinds of efforts and metabolic responses. Depending on exercise intensity, their skeletal muscle oxygenation decreases, and the reperfusion at cessation of the exercise can cause excessive production of free radicals. This study on cultured primary equine myoblasts investigated the effect of different kinds of anoxia/reoxygenation (A/R) on routine respiration, mitochondrial complex I specific activity and free radicals production. Our data revealed that short cycles of A/R caused a decrease of all the parameters, opposite to what a single long period of anoxia did. A preconditioning-like effect could explain our first pattern of results whereas mild uncoupling could be more appropriate for the second one. Anyway, it seems that mitochondrial complex I could play a major role in the regulation of the balance between metabolic and antioxidant protection of the muscular function of athletic horses.

Intra- and extracellular antioxidant capacities of the new water-soluble form of curcumin (NDS27) on stimulated neutrophils and HL-60 cells.

Phagocytic cells, especially neutrophils (PMNs) are specialized in the production of reactive oxygen species (ROS) to kill pathogenic agents, but an excessive ROS production is associated with tissue damages and inflammatory diseases. Phagocytes are thus prime therapeutic targets to control inflammatory events associated to ROS production. Nowadays, there is a growing interest for the use of polyphenols to modulate the inflammatory response. The aim of this work was to study the antioxidant effect of NDS27, a highly water-soluble form of the polyphenolic molecule curcumin, on in vitro stimulated equine PMNs and human promyelocytic leukemia cells (HL-60). NDS27 was either pre-incubated with cells and eliminated before their activation (intracellular effect) or let in the medium (extracellular effect). Our results indicate that NDS27 significantly and dose-dependently (10(-6) M-10(-4) M) inhibited the ROS production in both cell types without affecting their viability. NDS27 was able to cross and interact with cell membrane, especially for HL-60 cells, while we observed a better intracellular antioxidant effect with PMNs. The activity of myeloperoxidase (MPO) released by PMNs and HL-60 cells, was decreased by NDS27, but more efficiently for PMNs. These results suggested that the greater efficiency of NDS27 in PMNs is due to an inhibitory effect on cells which are more mature for ROS production, probably by targeting the enzymes implied in respiratory burst like MPO. The modulatory effect of NDS27 on the oxidant activity of cells involved in immune and inflammatory responses opens perspectives for a therapeutic control of pathologies with excessive inflammatory reactions.