Dogs with pituitary-dependent hyperadrenocorticism (PDH) are at increased risk of thromboembolic disease (TED); however the pathogenesis of thrombosis in these patients is poorly characterized. Thromboelastography (TEG®) is a whole blood hemostatic test that has recently been shown to be capable of detecting hypercoagulability in veterinary patients. A modification of TEG, PlateletMappingTM (TEG-PM) measures platelet response to the agonists arachidonic acid (MAAA) and adenosine diphosphate (MAADP), and compares this to fibrin clot strength in the absence of platelet activation (MAfibrin). This prospective study evaluated dogs with PDH for hypercoagulability using TEG-PM as well as conventional plasma-based coagulation tests (prothrombin time [PT], activated partial thromboplastin time [aPTT], fibrinogen concentration). Hemostatic testing was performed in 40 healthy dogs, 19 dogs with untreated PDH, 16 of the dogs with PDH after 3 months’ treatment and 15 dogs after 6 months’ treatment. Systolic blood pressure (SBP) was also measured in all the dogs with PDH before and during treatment. In addition, urine protein to creatinine ratio (UPCR) and antithrombin activity [AT] were measured in some dogs with PDH. PT was significantly decreased in the dogs with PDH compared to controls, however all of the dogs with PDH had results within the reference interval. Dogs with PDH were hyperfibrinogenemic compared to healthy dogs; fibrinogen concentrations reduced with treatment of PDH but remained significantly elevated. AT activity in the PDH dogs was not significantly decreased despite the majority of dogs tested having significant proteinuria. Approximately half of the dogs with untreated PDH were hypertensive, and blood pressure did not change significantly following resolution of hypercortisolemia. Serum cholesterol was increased in dogs with untreated PDH but normalized following control of PDH. TEG-PM revealed decreased κ, increased α-angle and increased MAthrombin in dogs with PDH in comparison to healthy dogs. Platelet response to AA was significantly increased in dogs with untreated PDH. Following treatment of PDH, the majority of TEG-PM parameters (with the exception of MAthrombin) did not change significantly. In conclusion, dogs with PDH had evidence of hypercoagulability and hypertension, which persisted despite medical treatment of PDH. These factors may explain the association between hyperadrenocorticism and TED. / OVC Pet Trust Fund, Vetoquinol

Objectives: To determine the effects of prednisone and prednisone plus ultralow-dose aspirin on coagulation in healthy dogs, and to determine intra-individual variation in thromboelastography (TEG). Animals: 14 healthy experimental dogs and 10 healthy client-owned dogs Procedures: Prospective, randomized, blinded study. TEG was performed twice three days apart on each experimental dog prior to treatment and intra-individual variation was calculated. Dogs were given prednisone (2 mg/kg/day) plus aspirin (0.5 mg/kg/day) or prednisone (2 mg/kg/day) plus placebo for 14 days, after which TEG and other baseline tests were repeated. Changes from baseline between and within each group were compared using t-tests or Wilcoxon 2 sample tests. Client owned dogs had TEG performed twice three days apart to determine intra-individual variation. Results: Intra-individual variation in TEG parameters were <10% for MA (maximum amplitude) and angle. For experimental dogs, MA and fibrinogen significantly increased from baseline whereas Ly30 (percent lysis 30 minutes after MA) and antithrombin activity significantly decreased within each group. For the prednisone plus placebo group, Ly60 (percent lysis 60 minutes after MA) significantly decreased from baseline. For all parameters, there was no difference between groups for change from baseline. Conclusions and Clinical Relevance: Prednisone caused hypercoagulability in healthy dogs evidenced by increased MA and fibrinogen and decreased antithrombin activity. Concurrent use of ultra-low dose aspirin had no effect on measured TEG parameters. Intra-individual variation in some TEG parameters is high and may preclude routine clinical utility. / Master of Science

The objective of the present study was to systematically evaluate the impact of methodology on thromboelastometry with canine whole blood. Thromboelastometry was performed on citrated blood using a variety of combinations of clotting activators [ex-tem (tissue factor or TF), in-tem (ellagic acid), diluted TF from Innovin, or Ca (recalcification only)] and storage times. Thromboelastometry was also performed using diluted TF from Innovin on blood collected into a contact inhibitor. Ex-vivo contact activation was compared between canine and human blood. Clotting activator had a marked impact on coagulation time, a minor impact on alpha angle, and no impact on clot formation time or maximum clot firmness. When ex-tem or in-tem was the clotting activator, sample storage up to 30 min did not affect results. With diluted TF from Innovin or Ca, sample storage was associated with the development of increased coagulability (as indicated by shorter coagulation time and clot formation time and higher alpha angle) due to ex-vivo contact activation. Canine blood underwent markedly more ex-vivo contact activation than did human blood. Canine blood undergoes significant ex-vivo contact activation during and after collection, which influences thromboelastometry results when a weak clotting activator (such as low TF or recalcification) is used. Thromboelastometry with a strong activator (such as ex-tem or in-tem) is less influenced by ex-vivo changes, and, therefore, likely to be more reflective of in-vivo hemostatic capabilities and to provide consistently interpretable and comparable results.

Background: Hyperthyroid cats are predisposed to thrombus formation. The mechanism for thrombogenesis is currently unknown, but could be associated with altered hemostasis as seen in hyperthyroid humans. Objective: The purpose of this study was to evaluate markers of hemostasis in hyperthyroid cats compared to healthy cats, and in hyperthyroid cats before and after treatments with radioactive iodine (RIT). Methods: Twenty-five cats with hyperthyroidism and 13 healthy euthyroid cats > 8 years of age were studied. Prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, antithrombin (AT), D-dimers, thrombin-antithrombin complexes (TAT), von Willebrand Factor antigen (vWF:Ag), and activity of factors VIII and IX were measured. An echocardiogram was performed in all cats and healthy cats with abnormal echocardiograms were excluded. Measurements of hemostasis were evaluated again in 7 cats > 6 months after RIT and deemed to have restored euthyroid status. Results: There is a significant likelihood of being in hypercoagulable state based on hyperthyroid state (P = 0.019) and serum T4 level is significantly associated with predicating hypercoagulability (P = 0.043). Hyperthyroidism is associated with significantly higher median fibrinogen concentration (P < 0.0001), higher median AT activity (P < 0.0001), and higher median vWF:Ag level (P = 0.01) with all values decreasing significantly post-RIT. Fibrinogen and AT had a strong positive correlation with serum T4 value (r = 0.79; 95% CI 0.63 - 0.89 and r = 0.70; 95% CI 0.50 - 0.84, respectively). Presence of an abnormal echocardiogram in hyperthyroid cats was associated with a significantly higher median fibrinogen concentration (P = 0.03). Echocardiographic status did not have a significant impact on the remaining hemostatic markers in hyperthyroid cats. Conclusions: These results provide evidence of altered hemostasis and hypercoagulability in hyperthyroid cats that do not appear to be solely attributed to cardiac abnormalities. These differences of altered hemostasis resolved after radioiodine therapy, but further studies are warranted to determine if hypercoagulable state resolves. / Master of Science / In feline hyperthyroidism, there is a predisposition for thrombus formation. An alteration of hemostasis has been documented in hyperthyroid humans, but despite reports of thrombus formation in hyperthyroid cats, the underlying mechanism is currently unknown. Hyperthyroidism can lead to cardiac abnormalities that could possibly contribute thrombus formation, although thrombus formation has occurred in hyperthyroid cats without detected abnormalities. The goal of this study was to evaluate markers of hemostasis in hyperthyroid cats presenting for radioiodine therapy to evaluate for presence of hypercoagulability. Twenty-five hyperthyroid cats were evaluated with hemostasis panels and echocardiograms. The results were compared to a group of 13 healthy cats. Markers of hemostasis and echocardiograms in 7 hyperthyroid cats were also compared to results 6 months or greater post-radioiodine therapy. There was evidence of altered hemostasis and hypercoagulability in hyperthyroid cats. The alterations noted resolved after radioiodine therapy and do not appear to be solely attributed to cardiac abnormalities seen in hyperthyroid cats.

Enoxaparin, a low-molecular-weight heparin, is commonly used as an anticoagulant in dogs, and is currently dosed at 0.8mg/kg every 6 hours. With an increase in individual enoxaparin doses, less frequent dosing may be possible, thereby reducing owner inconvenience and expense. The three phases of this study investigated the appropriate dose (Phase one- 0.8mg/kg, SQ once; Phase two- 2mg/kg, SQ once; Phase three- 1.3 mg/kg, SQ q8h for 7 total doses) and dosing interval needed for maximum effectiveness of enoxaparin. A Sonoclot® analyzer and factor Xa activity were used to assess level of anticoagulation in six healthy dogs. Anticoagulation was inconsistent at the 0.8mg/kg dose, while the 2mg/kg dose showed a high level of anticoagulation, and the 1.3mg/kg dose provided more reliable anticoagulation than the other dosages and dosing intervals. Small sample size and the use of same-breed healthy dogs potentially affected the strength of the results.

Objectifs: Etude de l'influence des cellules du pancréas d'adénocarcinome (BXPC3) et des cellules de carcinome du sein humain (MCF7) sur l'efficacité antithrombotique de l'apixaban, du fondaparinux et de l'énoxaparine. Recherche des mécanismes procoagulants des BXPC3 et MCF7.Méthodes: Les cellules sont cultivées sur plaques 96 puits. Un plasma normal pauvre ou riche en plaquettes est surchargé par des anticoagulants. La génération de thrombine (GT) est réalisée dans différentes conditions par le test CAT. Le facteur tissulaire alternatif épissé (asTF), l'activité du FT (FTa) et le cancer procoagulant (CP) sont évalués. Les cellules HUVEC servent de contrôle normal.Résultats: La comparaison sur la base de l’IC50 a montré qu'en présence de BXPC3 ou de MCF7, l'efficacité de l'apixaban a été préservée. Le fondaparinux est plus vulnérable par la présence de cellules cancéreuses. Le FTa et l’asTF sont plus abondants pour les BXPC3 que les cellules MCF7. La GT est médiée plus fortement par le FVII pour les BXPC3 que les MCF7. Le facteur XII était plus important pour la GT médiée par les MCF7. La présence de MPs augmente considérablement la production de thrombine et cet effet est fonction du type de cellules et leur origine.Conclusion: Le type de cellules cancéreuses est déterminant pour l'efficacité anti-thrombotique des inhibiteurs spécifiques du facteur Xa. La GT par les BXPC3 est dominée par la voie du FT. Le rôle du FXII est plus impliqué pour les MCF7. L'hypercoagulabilité induite par les cellules cancéreuses est la résultante de la combinaison des propriétés procoagulantes des cellules cancéreuses elles-mêmes et des éléments procoagulants du microenvironnement. / Aims: study of influence of pancreas adenocarcinoma cells (BXPC3) and human breast carcinoma cells (MCF7) on the antithrombotic efficiency of apixaban, fondaparinux and enoxaparin. Dissection of procoagulant mechanisms of BXPC3 and MCF7.Methods: Cells were cultured and adhered in 96-well plates. Normal platelet poor or rich plasma were spiked whit apixaban, fondaparinux or enoxaparin. Thrombin generation (TG) was done with CAT¨ assay in different conditions. Alternatively spliced TF (asTF), TF activity (TFa) and cancer procoagulant (CP) were assessed. Primary human umbilical vein cells (HUVEC) were used as normal control.Results: Comparison on the basis of IC50 showed that in the presence of BXPC3 or MCF7 the efficiency of apixaban was preserved. Fondaparinux was more vulnerable to the presence of cancer cells. The TFa and asTF were found in abundant amounts in BXCP3 than MCF7 cells. TG enhancement by BXPC3 and MCF7 was mediated by FVII. Factor XII was more important for TG enhancement by MCF7.The presence of MPs drastically increases the generation of thrombin and this effect depending of the type of their original cells.Conclusion: The type of cancer cells is determinant for the antithrombotic efficiency of the specific factor Xa inhibitors. The mechanism of activation of blood coagulation by the BXPC3 is dominated by the TF pathway, MCF7 additionally imply also FXII activation. The hypercoagulability induced by cancer cells is the resultant of the combination of the procoagulant properties of cancer cells with procoagulant elements of the plasma microenvironment and highlight that circulating MVs are key players in the pathogenesis of cancer-associated thrombosis.

Orientadores: Fabíola Traina, Erich Vinícius de Paula / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-24T00:53:36Z (GMT). No. of bitstreams: 1 Colella_MarinaPereira_D.pdf: 9236093 bytes, checksum: efa509cf78d63c66379b975a9b095ac8 (MD5) Previous issue date: 2013 / Resumo: A anemia falciforme (AF) é caracterizada pela presença de crises vaso-oclusivas e hemólise intravascular com consequente depleção de óxido nítrico, ativação endotelial e inflamação crônica. Praticamente todos os elementos da coagulação estão alterados na direção pró-coagulante na AF, de forma que uma incidência aumentada de eventos tromboembólicos tem sido descrita nesta doença. A hidroxiuréia é atualmente um dos pilares do tratamento destes pacientes, tendo como principal ação induzir um aumento da hemoglobina fetal. A hemoglobinopatia SC (HbSC) é a segunda hemoglobinopatia mais prevalente após a AF. Sabe-se que há uma incidência elevada de eventos tromboembólicos na HbSC, porém conhece-se muito pouco sobre a ativação da coagulação nesta doença. O presente estudo foi dividido em duas partes, tendo dois objetivos principais: (1) testar a hipótese de que a hidroxiuréia teria um efeito benéfico no estado de hipercoagulabilidade visto na AF; (2) avaliar o estado de hipercoagulabilildade presente na HbSC. Na primeira parte do estudo avaliamos a ação da hidroxiuréia nos principais componentes do balanço hemostático em pacientes com AF tratados (SS-HU) ou não (SS) com hidroxiureia; e estudamos o efeito da hidroxiureia na ativação final da coagulação em um modelo murino de AF incapaz de expressar a hemoglobina fetal. Nossos resultados mostraram que o tratamento com hidroxiuréia esteve associado com melhora dos marcadores de ativação da coagulação, incluindo redução na expressão gênica de fator tecidual (FT) (5.0[SS] vs. 2.6[SS-HU], p=0.02) e diminuição nos níveis plasmáticos de FT (p=0.01), complexo trombina-antitrombina III (TAT) (11.5[SS] vs. 7.5[SS-HU], p=0.03) e fragmento 1+2 da protrombina (301.5[SS] vs. 245[SS-HU], p=0.09). Os pacientes tratados com hidroxiuréia também apresentaram reduções significativas dos níveis de trombomodulina solúvel (3.6[SS] vs. 2.5[SS-HU], p=0.0007) e fator de necrose tumoral alfa (TNF-_) (2.7[SS] vs. 0.3[SS-HU], p<0.0001). A redução dos marcadores de hipercoagulabilidade apresentou correlações significativas com o aumento da HbF e reduções dos marcadores de hemólise, ativação endotelial e inflamação. Em modelo murino de AF, a hidroxiuréia resultou em diminuição dos níveis plasmáticos de TAT (138.5[salina] vs. 106.7[HU], p=0.05). Esses resultados fornecem evidências de um efeito benéfico da hidroxiuréia em reduzir o estado de hipercoagulabilidade na AF. Na segunda parte do presente estudo, nós avaliamos os diversos componentes do balanço hemostático nos pacientes com HbSC e comparamos com os pacientes AF (SS e SS-HU). A comparação dos marcadores de hipercoagulabilidade entre pacientes HbSC e AF revelou que a expressão gênica do FT foi semelhante ao encontrado na AF (2.6[SC] vs. 3.1[SS+SS-HU], p=0.2), enquanto os níveis de TAT e D-dímero foram inferiores (TAT: 4.2[SC] vs. 7.4[SS+SS-HU], p<0.0001; D-dímero: 710.4[SC] vs. 1495[SS+SS-HU], p=0.0003). Em comparação com pacientes com AF, os pacientes com HbSC apresentaram níveis semelhantes de trombomodulina solúvel (3.2[SC] vs. 3.0[SS+SS-HU], p=0.6), TNF-_ (2.7[SC] vs. 2.2[SS+SSHU], p=0.5), e níveis inferiores de interleucina 8 (2.5[SC] vs. 3.2[SS+SS-HU], p=0.05). Dentre os pacientes com HbSC os marcadores de hipercoagulabilidade também apresentaram correlações significativas com marcadores de hemólise e inflamação. Em conclusão, nossos resultados fornecem evidências de um efeito benéfico da hidroxiuréia em reduzir o estado de hipercoagulabilidade na AF e demostram que existe uma ativação da coagulação na HbSC quando comparados a indivíduos normais, porém não tão intensa quanto a vista na AF / Abstract: Sickle cell anemia is characterized by the presence of vaso-occlusive crises and intravascular hemolysis with consequent depletion of nitric oxide, endothelial activation and chronic inflammation. Virtually all of the components of coagulation are altered in the procoagulant direction in sickle cell anemia, and thus an increased incidence of thromboembolic events has been described in this disease. Hydroxyurea is currently one of the mainstays of treatment of these patients, with the primary action of inducing an increase in fetal hemoglobin. Hemoglobin SC disease is the second most prevalent hemoglobinopathy after sickle cell anemia. There is a high incidence of thromboembolic events in hemoglobin SC disease, but very little is known about the activation of coagulation in this disease. This study was divided into two parts, with two main objectives: (1) test our hypothesis that hydroxyurea would have a beneficial effect on the hypercogulable state seen in sickle cell anemia; (2) evaluate the hypercoagulable state present in hemoglobin SC disease. In the first part of this study we evaluated the effect of hydroxyurea in the main components of the hemostatic balance of sickle cell anemia patients treated (SS-HU) or not (SS) with the drug; and we also evaluated the effect of hydroxyurea on thrombin generation in a sickle cell murine model, uncapable of expressing fetal hemoglobin. Our results showed that treatment with hydroxyurea was associated with reduced markers of coagulation activation, including a reduction in the expression of the tissue factor gene (5.0[SS] vs. 2.6[SS-HU], p=0.02) and in plasma levels of tissue factor (p=0.01), thrombin-antithrombin complex III (TAT) (11.5[SS] vs. 7.5[SS-HU], p=0.03), and prothrombin fragment 1+2 (301.5[SS] vs. 245[SS-HU], p=0.09). Patients treated with hydroxyurea also presented reductions in the levels of soluble thrombomodulin (3.6[SS] vs. 2.5[SS-HU], p=0.0007) and tumor necrosis fatoralpha (TNF-_) (2.7[SS] vs. 0.3[SS-HU], p<0.0001). Hypercoagulability markers presented significant correlations with the increase in fetal hemoglobin levels and reductions in hemolysis, endothelial activation and inflammation markers. In the murine model of sickle cell anemia hydroxyurea resulted in reduction of plasma levels of TAT (138.5[saline] vs. 106.7[HU], p=0.05). These results provide evidence that treatment with hydroxyurea has a beneficial effect of reducing the hypercoagulability state seen in sickle cell anemia. In the second part of this study, we studied the various components of the hemostatic balance in hemoglobin SC disease patients and compared them with sickle cell anemia patients (SS and SS-HU). The gene expression of tissue fator was similar to the expression seen in sickle cell anemia (2.6[SC] vs. 3.1[SS+SS-HU], p=0.2), while the levels of TAT and D-dimer were lower (TAT: 4.2[SC] vs. 7.4[SS+SS-HU], p<0.0001; D-dimer: 710.4[SC] vs. 1495[SS+SS-HU], p=0.0003). In comparison to patients with sickle cell anemia, patients with hemoglobin SC disease presented similar levels of soluble thrombomodulin (3.2[SC] vs. 3.0[SS+SS-HU], p=0.6), TNF-_ (2.7[SC] vs. 2.2[SS+SS-HU], p=0.5), and lower levels of interleukin 8 (2.5[SC] vs. 3.2[SS+SS-HU], p=0.05). In hemoglobin SC patients, the hypercoagulability markers presented significant correlations with hemolysis and inflammation markers. In conclusion, our results provide evidence that treatment with hydroxyurea has a beneficial effect of reducing the hypercoagulability state seen in sickle cell anemia, and that there is an activation of coagulation in hemoglobin SC disease when compared to normal individuals, but not as intense as seen in sickle cell anemia / Doutorado / Clinica Medica / Doutora em Clínica Médica

Diabetes mellitus, which is largely driven by nutritional and behavioral factors, is characterized by accelerated atherosclerosis with impaired plaque stability. Atherosclerosis and associated complications are the major cause of mortality in diabetic patients. Efficient therapeutic concepts for diabetes-associated atherosclerosis are lacking. Atherosclerosis among diabetic patients is associated with reduced endothelial thrombomodulin (TM) expression and impaired activated protein C (aPC) generation. Here, we demonstrate that atherosclerotic plaque stability is reduced in hyperglycemic mice expressing dysfunctional TM (TMPro/Pro mice), which have a pro-coagulant phenotype due to impaired thrombin inhibition and markedly reduced aPC generation. The vessel lumen and plaque size of atherosclerotic lesions in the truncus brachiocephalic were decreased in diabetic TMPro/Pro ApoE-/- mice compared to diabetic ApoE-/- mice. While lipid accumulation in lesions of diabetic TMPro/Pro ApoE-/- mice was lower than that in diabetic ApoE-/- mice, morphometric analyses revealed more prominent signs of instable plaques, such as a larger necrotic core area and decreased fibrous cap thickness in diabetic TMPro/Pro ApoE-/- mice. Congruently, more macrophages and fewer smooth muscle cells were observed within lesions of diabetic TMPro/Pro ApoE-/- mice. Thus, impaired TM function reduces plaque stability, a characteristic of hyperglycemia-associated plaques, thus suggesting the crucial role of impaired TM function in mediating diabetes-associated atherosclerosis.