Comparative blood coagulation studies in the ostrich

Frost, Carminita; Naudé, Ryno J.; Oelofsen, Willem; Jacobson, Barry

doi:10.1016/s0162-3109(99)00058-2

Cited by 35 publications

(20 citation statements)

References 21 publications

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“…44,45 Despite this, there is no evidence of deterioration of the fXI gene, 44 indicating that its product remains under selection pressure because it provides an adaptive function. Similarly, birds lack fXII [46][47][48] but have an intact gene for the fXI/PK predecessor. 1 Here, there is convincing evidence that the fXII gene was lost along the lineage leading from reptiles to birds.…”

Section: Discussionmentioning

confidence: 99%

Factor XI contributes to thrombin generation in the absence of factor XII

Kravtsov

Matafonov

Tucker

et al. 2009

Blood

135

151

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During surface-initiated blood coagulation in vitro, activated factor XII (fXIIa) converts factor XI (fXI) to fXIa. Whereas fXI deficiency is associated with a hemorrhagic disorder, factor XII deficiency is not, suggesting that fXI can be activated by other mechanisms in vivo. Thrombin activates fXI, and several studies suggest that fXI promotes coagulation independent of fXII. However, a recent study failed to find evidence for fXII-independent activation of fXI in plasma. Using plasma in which fXII is either inhibited or absent, we show that fXI contributes to plasma thrombin generation when coagulation is initiated with low concentrations of tissue factor, factor Xa, or ␣-thrombin. The results could not be accounted for by fXIa contamination of the plasma systems. Replacing fXI with recombinant fXI that activates factor IX poorly, or fXI that is activated poorly by thrombin, reduced thrombin generation. An antibody that blocks fXIa activation of factor IX reduced thrombin generation; however, an antibody that specifically interferes with fXI activation by fXIIa did not. The results support a model in which fXI is activated by thrombin or another protease generated early in coagulation, with the resulting fXIa contributing to sustained thrombin generation through activation of factor IX. (Blood. 2009;114:452-458) IntroductionThe plasmas of placental and marsupial mammals contain factor XI (fXI), 1 the zymogen of a protease (fXIa) that contributes to fibrin formation and stability through activation of factor IX (fIX). [2][3][4] Congenital fXI deficiency is associated with a variable traumainduced bleeding disorder in humans and other species. [5][6][7][8] The mechanism by which fXI is converted to fXIa during blood coagulation has been a topic of recent debate. 9,10 When blood is exposed to a surface in vitro, the process of contact activation converts factor XII (fXII) to the protease fXIIa, which then activates fXI. 3,4 Substances, such as RNA, 11 polyphosphates, 12 and collagen, 13 induce pathologic coagulation in mice in a fXIIdependent manner 13,14 and may represent physiologic surfaces for fXII activation. However, the contribution of fXIIa-mediated fXI activation to normal hemostasis is unclear, as fXII deficiency, unlike fXI deficiency, is not associated with abnormal bleeding in any species in which it has been identified. 4 This key observation supports hypotheses proposing that fXI is either activated during hemostasis by a protease other than fXIIa or that auxiliary mechanisms for fXI activation compensate in the absence of fXII. 3,[15][16][17] Candidates for fXI-activating proteases include ␣-thrombin, 15,16 meizothrombin, 18 and fXIa (autoactivation). 15,16 Thrombin has received much attention in this regard. Several laboratories have presented evidence suggesting that a protease generated early in coagulation, such as thrombin, converts fXI to fXIa. [19][20][21][22][23] This hypothesis has been challenged by a recent study that did not find evidence for fXI activation in thrombin or tissue facto...

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Section: Discussionmentioning

confidence: 99%

Factor XI contributes to thrombin generation in the absence of factor XII

Kravtsov

Matafonov

Tucker

et al. 2009

Blood

135

151

View full text Add to dashboard Cite

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“…Ostriches are well-studied avians for the coagulation cascade and xenobiotic-metabolizing enzymes (Frost et al, 1999;Amsallem-Holtzman and Ben-Zvi, 1997).…”

Section: Discussionmentioning

confidence: 99%

“…The coagulation system or the coagulation factors of avian species can be different from mammal (Thomson et al, 2002). In ostriches, the vitamin K-dependent coagulation factors, such as factor II, IIV, IX and X, are known to have low or no activity (Frost et al, 1999).…”

Section: Discussionmentioning

confidence: 99%

Comparison of warfarin sensitivity between rat and bird species

Watanabe

Saengtienchai

Tanaka

et al. 2010

Comparative Biochemistry and Physiology Part C: Toxicology &

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Scattering coumarin-derivative rodenticides in broad areas have caused primary-and secondary-poisoning incidents in non-target wild birds. In this study, we compared factors determining warfarin sensitivity between bird species and rats based on vitamin K 2,3-epoxide reductase (VKOR) kinetics, VKOR inhibition by warfarin and warfarin metabolism assays. In VKOR characterization, chickens and ostriches showed significantly lower enzymatic efficiencies than rats (one-sixth and one-third, respectively), suggesting bird species depend more on a non-VKOR vitamin K source. On the other hand, the inhibition constants (K i ) of VKOR for warfarin were significantly different between chickens and ostriches (11.3 ± 2.5 μM and 0.64 ± 0.39 μM, respectively). Interestingly, the ostrich K i was similar to the values for rats (0.28 ± 0.09 μM). The K i results reveal a surprising possibility that VKOR in some bird species are easily inhibited by warfarin. Warfarin metabolism assays also showed a large inter-species difference in bird species. Chickens and ostriches showed higher metabolic activity than that of rats, while mallards and owls showed only a slight ability to metabolize warfarin. In this study, we clarified the wide inter-species difference that exists among birds in xenobiotic metabolism and sensitivity to a rodenticide.

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“…Clotting time was noted when no plasma flow could be observed and plasma was immobilized in the glass tubes. Recalcification assays were performed with chicken plasma, as chickens lack a functional intrinsic pathway (APTT test) and the extrinsic pathway (PTT test) does not work with heterologous tissue factor (Frost et al, 1999). Under the conditions used chicken plasma only clotted after 15-20 min of incubation at 37 1C compared to the APTT and PTT tests with human plasma that clotted within 100 s.…”

Section: Assay For Clotting Factorsmentioning

confidence: 99%

Characterization of anti-hemostatic factors in the argasid, Argas monolakensis: Implications for the evolution of blood-feeding in the soft tick family

Mans

Andersen

Schwan

et al. 2008

Insect Biochemistry and Molecular Biology

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To date, the only anti-hemostatic factors characterized for softs ticks are for Ornithodoros moubata and Ornithodoros savignyi, ticks that feeds mainly on mammals. This includes thrombin (ornithodorin and savignin), fXa (TAP and fXaI) and platelet aggregation (disagegin and savignygrin) inhibitors that belong to the BPTI-Kunitz protein family. This raises the question on how well anti-hemostatic factors will be conserved in other soft tick genera that feeds on other vertebrates such as birds. We characterized the anti-hemostatic factors from Argas monolakensis, a soft tick that feeds mainly on Californian gulls. The main anti-clotting factor (monobin) is an ortholog of ornithodorin and savignin and shows similar slow tight-binding kinetics. The main anti-platelet activities are apyrase and fibrinogen receptor antagonists (monogrins). The monogrins are orthologs of disagregin and savignygrin and like savignygrin presents the RGD integrin-recognition motif on the BPTI substrate-binding presenting loop. This implies that the anti-hemostatic factors evolved in the ancestral soft tick lineage and has been maintained in soft tick species from two distinct genera with different host preferences. The Argas derived anti-hemostatic factors bind to mammalian targets with affinities similar to that observed for their orthologs in the Ornithodoros genus. This cross-reactivity could have facilitated the switching of soft ticks from avian to mammalian hosts and can explain in part the ability of Argas ticks, to feed on humans, thereby remaining a possible health risk.

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Comparative blood coagulation studies in the ostrich

Cited by 35 publications

References 21 publications

Factor XI contributes to thrombin generation in the absence of factor XII

Factor XI contributes to thrombin generation in the absence of factor XII

Comparison of warfarin sensitivity between rat and bird species

Characterization of anti-hemostatic factors in the argasid, Argas monolakensis: Implications for the evolution of blood-feeding in the soft tick family

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