Background: The risk of ischaemic stroke in patients with atrial fibrillation (AF) and mechanical heart valve (MHV) prostheses can be reduced by oral anticoagulation (OAC), which increases the risk of serious bleeding. The aims of this thesis were [1] to find out how effective and safe warfarin is where treatment quality is high, i.e. Sweden, with proportion of time that patients spend within the therapeutic range (TTR) &gt;70%, [2] whether there is evidence for administering low-molecular-weight heparin (LMWH) during temporary interruptions of OAC (bridging therapy), and whether non-vitamin K-dependent oral anticoagulants (NOACs) as a group, [3] or individually, [4] are more effective and safer than warfarin when used for stroke prevention in patients with AF. Materials and methods: All four studies were retrospective, based on the Swedish anticoagulation register Auricula, and done with merging of data from some or all of the National Patient Register, the Prescribed Drug Register, the Swedish Stroke Register (Riksstroke), and the Cause of Death Register. In studies 2–4, propensity score matching was performed to obtain treatment groups with similar risk profiles. Outcomes were defined as haemorrhages or thromboses requiring specialist care, or death. Haemorrhages were intracranial, gastrointestinal, or other. Thromboses were ischaemic stroke, systemic embolism, myocardial infarction, or venous thromboembolism (VTE). Study 1 described all patients on warfarin during 2006–2011, which was before the introduction of NOACs. Study 2 was a cohort study of all patients who had a planned interruption of warfarin during the same period. Study 3 included all 49,011 patients starting OAC for stroke prevention due to AF between 1 July 2011 and 31 December 2014, and study 4 all 64,382 patients with the same indication between 1 January 2013 and 31 December 2015. Results: Study 1 showed that for the 77,423 patients on warfarin with 217,804 treatment years, TTR was 77.4% for patients with AF, 74.5% with MHV, and 75.9% with VTE. Annual rates of intracranial bleeding were 0.38%, 0.51%, and 0.30%. In study 2, with 14,556 warfarin interruptions, the 30-day risk of a bleeding requiring specialist care was 0.64% for LMWH treated and 0.46% for controls. For patients with VTE as indication for OAC, bleeding rate with LMWH was significantly higher at 0.85% vs. 0.16% (hazard ratio 5.24, 95% confidence interval 1.39–19.77), but with no difference for patients with MHV or AF. The incidence of ischaemic complications was higher in the LMWH bridging group overall and for patients with MHV and AF, but not for patients with VTE. In study 3, for the 12,694 patients starting NOAC (10,392 treatment years) or matched warfarin patients (9,835 treatment years, TTR 70%) due to AF, annual incidence of ischaemic stroke and systemic embolism did not differ between the groups (1.35% vs. 1.58%), but risks of major bleedings and intracranial bleedings were significantly lower: 2.76% vs. 3.61% and 0.40% vs. 0.69%. In study 4, patients on individual NOACs (6,574 dabigatran, 8,323 rivaroxaban, 12,311 apixaban) were compared to 37,174 patients starting warfarin (in total 81,176 treatment years). No NOAC showed any difference in risk of ischaemic stroke or systemic embolism, but there were fewer intracranial bleedings, serious bleedings overall, and deaths for dabigatran and apixaban compared to warfarin. For patients starting rivaroxaban the risk of gastrointestinal bleeding was higher than for matched warfarin counterparts, with no significant differences in other bleeding risks, or mortality. Conclusions: Swedish warfarin treatment shows TTR levels that are high by international standards, correlating to low incidences of ischaemic and haemorrhagic events. LMWH bridging has not been proven beneficial, even for patients with MHV, meaning that bridging in general cannot be recommended. NOACs as a group were safer than high-quality warfarin treatment. Efficacy did not differ, even when comparing individual NOACs to warfarin, but there were fewer bleedings on dabigatran and apixaban. Although not more efficient than warfarin with a high TTR, NOACs should be the recommended first choice for OAC in AF, on the merit of lower bleeding risks. / <p>Finansiär: Forskning och Utveckling, Region Västernorrland</p>

Anticoagulants, also known as antithrombotics, are among the most commonly prescribed medications in the United States. Understanding how these medications work, the propensity for interactions with other drugs, dietary factors, and disease states is important for clinicians assessing and providing care to patients in all environments. In this review, we seek to provide essential information for the home health care provider for evaluating patients receiving anticoagulants commonly prescribed in the home health care setting. The low-molecular-weight heparins and vitamin K antagonists are the most commonly used agents for outpatient anticoagulation. New agents, such as the direct factor Xa inhibitors and direct thrombin inhibitors have recently been approved with additional new agents in the approval process and development pipeline. We seek to review the most pertinent information for each of these classes of medications providing information on pharmacology, interactions with other drugs, diet, and diseases and important clinical information.

Subcutaneous anticoagulant medications like Heparin and Low-Molecular Weight Heparin are injections that readily cause bruising, pain, induration, and hematoma formation at the injection site. It is known that these adverse reactions can be correlated to the technique used to administer these medications; however, there is no established technique that reduces bruising, pain, induration, and hematoma formation at the site. Currently, the only protocol for subcutaneous Heparin and Low-Molecular Weight Heparin is that it is to be administered subcutaneously in the abdomen and when using a prefilled syringe, the air bubble should not be removed. The purpose of this study was to identify current nursing practice for the administration of these medications and to compare the results to researched techniques that resulted in less adverse site reactions. A total of 33 participants were recruited. The survey targeted six researched techniques found, after a comprehensive literature review, to have reduced site adverse effects associated with subcutaneous Heparin and Low-Molecular Weight Heparin. After completing the survey, it was found that current practice does not reflect techniques researched to reduce bruising, pain, induration, and hematoma formation at the site. In fact, very few completed one of the six research techniques that were questioned, which included: a two minute application of a cold compress/pack before and/or after the injection, an injection duration lasting 30 seconds, slow removal of the needle over five seconds, application of pressure after the injection for a minimum of 30 seconds, use of a hot pack/compress after the injection, and the use of a3 mL syringe. It was also found that there were inconsistencies in techniques that have been previously established as current protocol for these medications.

Hypercoagulable states occur when the process of hemostasis is disturbed. It manifests as a deep vein thrombosis or a pulmonary embolism. It is also one of the most common cardiovascular diseases. There are two factors- genetic and acquired. Inherent factors involve coagulation inhibitor deficiency, prothrombin gene mutation and activated protein C resistance. Acquired factors include antiphospolipid syndrome, pregnancy, overweight etc. The analytic part of the thesis is focused on the effect of a low molecular weight heparin. It was shown in many theses that the LMWH could have a negative impact on a parturition complications or a week of parturition, a birth weight. The results of statistical analysis show that there is a coherence between the week of parturition and the type of parturition. What is more, the anticoagulation drug therapy shows a positive effect on the week of parturion. The data used in the thesis originate in laboratory information management system of Clinical Haematology ward in the hospital Nemocnice České Budějovice a.s.

Immune heparin-induced thrombocytopenia (HIT) is a potentially serious complication of heparin therapy and is associated with antibodies directed against a complex of platelet factor 4 (PF4) and heparin. Early diagnosis of HIT is important to reduce morbidity and mortality. I developed an enzyme immunoassay that detects the binding of HIT IgG to PF4-heparin in the fluid phase. This required techniques to purify and biotinylate PF4. The fluid phase assay produces consistently low background and can detect low levels of anti-PF4-heparin. It is suited to testing alternative anticoagulants because, unlike in an ELISA, a clearly defined amount of antigen is available for antibody binding. I was able to detect anti-PF4-heparin IgG in 93% of HIT patients. I also investigated cross-reactivity of anti-PF4-heparin antibodies with PF4 complexed to alternative heparin-like anticoagulants. Low molecular weight heparins cross-reacted with 88% of the sera from HIT patients while half of the HIT sera weakly cross-reacted with PF4-danaparoid (Orgaran). The thrombocytopenia and thrombosis of most of these patients resolved during danaparoid therapy, indicating that detection of low affinity antibodies to PF4-danaparoid by immunoassay may not be an absolute contraindication for danaparoid administration. While HIT patients possess antibodies to PF4-heparin, I observed that HIT antibodies will also bind to PF4 alone adsorbed on polystyrene ELISA wells but not to soluble PF4 in the absence of heparin. Having developed a technique to affinity-purify anti-PF4-heparin HIT IgG, I provide the first estimates of the avidity of HIT IgG. HIT IgG displayed relatively high functional affinity for both PF4-heparin (Kd=7-30nM) and polystyrene adsorbed PF4 alone (Kd=20-70nM). Furthermore, agarose beads coated with PF4 alone were almost as effective as beads coated with PF4 plus heparin in depleting HIT plasmas of anti-PF4-heparin antibodies. I conclude that the HIT antibodies which bind to polystyrene adsorbed PF4 without heparin are largely the same IgG molecules that bind PF4-heparin and thus most HIT antibodies bind epitope(s) on PF4 and not epitope(s) formed by part of a PF4 molecule and part of a heparin molecule. Binding of PF4 to heparin (optimal) or polystyrene/agarose (sub-optimal) promotes recognition of this epitope. Under conditions that are more physiological and sensitive than previous studies, I observed that affinity-purified HIT IgG will cause platelet aggregation upon the addition of heparin. Platelets activated with HIT IgG increased their release and surface expression of PF4. I quantitated the binding of affinity-purified HIT 125I-IgG to platelets as they activate in a plasma milieu. Binding of the HIT IgG was dependent upon heparin and some degree of platelet activation. Blocking the platelet Fc??? receptor-II with the monoclonal antibody IV.3 did not prevent HIT IgG binding to activated platelets. I conclude that anti-PF4-heparin IgG is the only component specific to HIT plasma that is required to induce platelet aggregation. The Fab region of HIT IgG binds to PF4-heparin that is on the surface of activated platelets. I propose that only then does the Fc portion of the bound IgG activate other platelets via the Fc receptor. My data support a dynamic model of platelet activation where released PF4 enhances further antibody binding and more release.

Immune heparin-induced thrombocytopenia (HIT) is a potentially serious complication of heparin therapy and is associated with antibodies directed against a complex of platelet factor 4 (PF4) and heparin. Early diagnosis of HIT is important to reduce morbidity and mortality. I developed an enzyme immunoassay that detects the binding of HIT IgG to PF4-heparin in the fluid phase. This required techniques to purify and biotinylate PF4. The fluid phase assay produces consistently low background and can detect low levels of anti-PF4-heparin. It is suited to testing alternative anticoagulants because, unlike in an ELISA, a clearly defined amount of antigen is available for antibody binding. I was able to detect anti-PF4-heparin IgG in 93% of HIT patients. I also investigated cross-reactivity of anti-PF4-heparin antibodies with PF4 complexed to alternative heparin-like anticoagulants. Low molecular weight heparins cross-reacted with 88% of the sera from HIT patients while half of the HIT sera weakly cross-reacted with PF4-danaparoid (Orgaran). The thrombocytopenia and thrombosis of most of these patients resolved during danaparoid therapy, indicating that detection of low affinity antibodies to PF4-danaparoid by immunoassay may not be an absolute contraindication for danaparoid administration. While HIT patients possess antibodies to PF4-heparin, I observed that HIT antibodies will also bind to PF4 alone adsorbed on polystyrene ELISA wells but not to soluble PF4 in the absence of heparin. Having developed a technique to affinity-purify anti-PF4-heparin HIT IgG, I provide the first estimates of the avidity of HIT IgG. HIT IgG displayed relatively high functional affinity for both PF4-heparin (Kd=7-30nM) and polystyrene adsorbed PF4 alone (Kd=20-70nM). Furthermore, agarose beads coated with PF4 alone were almost as effective as beads coated with PF4 plus heparin in depleting HIT plasmas of anti-PF4-heparin antibodies. I conclude that the HIT antibodies which bind to polystyrene adsorbed PF4 without heparin are largely the same IgG molecules that bind PF4-heparin and thus most HIT antibodies bind epitope(s) on PF4 and not epitope(s) formed by part of a PF4 molecule and part of a heparin molecule. Binding of PF4 to heparin (optimal) or polystyrene/agarose (sub-optimal) promotes recognition of this epitope. Under conditions that are more physiological and sensitive than previous studies, I observed that affinity-purified HIT IgG will cause platelet aggregation upon the addition of heparin. Platelets activated with HIT IgG increased their release and surface expression of PF4. I quantitated the binding of affinity-purified HIT 125I-IgG to platelets as they activate in a plasma milieu. Binding of the HIT IgG was dependent upon heparin and some degree of platelet activation. Blocking the platelet Fc??? receptor-II with the monoclonal antibody IV.3 did not prevent HIT IgG binding to activated platelets. I conclude that anti-PF4-heparin IgG is the only component specific to HIT plasma that is required to induce platelet aggregation. The Fab region of HIT IgG binds to PF4-heparin that is on the surface of activated platelets. I propose that only then does the Fc portion of the bound IgG activate other platelets via the Fc receptor. My data support a dynamic model of platelet activation where released PF4 enhances further antibody binding and more release.

No description available.

Le microenvironnement des cellules tumorales présente plusieurs particularités comme l'hypoxie, l'acidification du milieu extracellulaire et l'hypersécrétion d'enzymes hydrolytiques. Ces hydrolases, comme la cathepsine D et l'héparanase, interviennent dans les étapes de la progression tumorale et notamment l'angiogenèse. Cette thèse s'intègre dans un projet dont la finalité est de concevoir un nano-objet moléculaire enzymo-sensible qui réagirait d'une manière spécifique aux enzymes hypersécrétées dans le microenvironnement tumoral pour assurer de façon simultanée, une fonction de détection et de ciblage des tumeurs. La première partie de nos travaux a été consacrée à la conception et à la validation d'un lien peptidique intégrable dans l'objet moléculaire, sensible aux formes de la cathepsine D actives du microenvironnement tumoral de cancers mammaires. Cet objectif a été réalisé suite à l'étude cinétique de l'hydrolyse de 5 peptides par la cathepsine D mature et la pro-cathepsine D dans les conditions de pH du microenvironnement tumoral. Nous avons également étudié l'effet de l'hypoxie et de l'acidification du milieu extracellulaire sur la sécrétion des formes actives de la cathepsine D par la lignée tumorale de cancer mammaire MCF-7. Dans une deuxième partie, nous avons travaillé sur l'élaboration d'héparines de bas poids moléculaire pouvant assurer la fonction thérapeutique de l'objet moléculaire grâce à leur activité anti-angiogénique. Nous avons mis au point une méthode innovante pour la dépolymérisation de l'héparine qui consiste en une hydrolyse radicalaire par le péroxyde d'hydrogène assistée par les ultrasons. Cette technique permet la production d'oligosaccharides d'héparines caractérisées par des poids moléculaires et des degrés de sulfatation contrôlés. En fonction des conditions de dépolymérisation par cette technique, les héparines de bas poids moléculaires produites peuvent être utilisées comme anticoagulant ou anti-angiogénique. / Tumor microenvironment is characterized by several particularities such as hypoxia, extracellular media acidification and the hyper-secretion of hydrolytic enzymes. These hydrolases, such as cathepsin D and heparanase, are involved in many steps of tumor progression like angiogenesis. This thesis is a part of a project that aims to develop a "smart" molecular nano-object that specifically reacts to hyper-secreted enzymes in the tumor microenvironment for the simultaneous detection and targeting of tumor. The first part of our work concerned the design and the validation of a peptide that is sensitive to active forms of cathepsin D which is a protease, unregulated in many tumors microenvironment such as breast cancers. This objective has been achieved following the kinetic study of the hydrolysis of 5 peptides by mature cathepsin D and procathepsin D in the pH conditions of the tumor microenvironment. On the other hand, we studied the effect of hypoxia and the acidification of the extracellular medium on the secretion of active forms of cathepsin D by the breast cancer cell line MCF-7. In a second part, we worked on the development of low molecular weight heparins that may provide therapeutic function of the molecular object through their anti-angiogenic activity. We have developed an innovative method for the depolymerization of heparin that consists on a radical hydrogen peroxide hydrolysis assisted by ultrasound. This technique allows the production of heparins oligosaccharides characterized by controlled molecular weight and degree of sulfatation. Depending on the depolymerization conditions by this technique, the produced low molecular weight heparins can be used as an anticoagulant or anti-angiogenic.

Nous avons mené une étude prospective randomisée dans le but de comparer l'effet de l'irrigation du cathéter de type PICC avec deux types d'anticoagulants: Héparine standard et Tinzaparine, une héparine de faible poids moléculaire. Notre étude s'adresse aux patients de la clinique externe d'oncologie de l'hôpital Maisonneuve-Rosemont. Entre début Mai 2005 et Mars 2008, nous avons recruté 131 patients dont 70 ont été randomisés. Parmi les 61 patients exclus, 23 n'ont pas rencontré les critères d'inclusion, 30 ont refusé de participer et 8 ne sont pas inclus pour d'autres raisons. Sur les 70, 36 sujets sont randomisés dans le groupe Héparine standard et 34 dans le groupe Tinzaparine. La population en intention de traiter comprend 65 sujets dont 32 dans le groupe Héparine standard et 33 dans le groupe Tinzaparine. Le médicament a été administré pendant un mombre maximal de 30 jours et les sujets ont été suivis pendant 90 jours. La thrombose veineuse associée au cathéter (TVAC) a été objectivée par une phlébographie ou une échographie-Doppler à la fin de la période de 30 jours suivant l'installation du cathéter. L'incidence de la TVAC sur 30 jours est de 14,39 par 1000 cathéter-jours (IC à 95%:[9,0;19,79]/1000 cathéter-jours ou 41,5% (27/65). L'incidence de la thrombose veineuse profonde (TVP) symptômatique du membre supérieur sur la période de suivi de 90 jours est de 0,41 par 1000 cathéter-jours (IC à 95%:[0,08;0,81]/1000 cathéter-jours ou 3% (2/65). Nous n'avons observé aucune différence entre les deux groupes par rapport à la fréquence de la TVAC ni de la TVP. Nous ne pouvons conclure à une différence dans l'efficacité de la Tinzaparine par rapport à l'Héparine standard dans la prévention de la TVAC. / Our prospective, randomized study aims at comparing the effectiveness of two types of heparin used for the instillation of peripherally inserted central catheter (PICC): Standard heparin and Tinzaparin, a low molecular weight heparin. We recruited patients from the ambulatory center of Maisonneuve-Rosemont hospital. Between the beginning of May 2005 and March 2008, 131 patients were enrolled. Of 61 patients excluded, 23 did not satisfy the inclusion criteria, 30 refused to participate and 8 were not enrolled for other reasons. Seventy patients were randomized into two groups, 36 in the Standard heparin group and 34 in the Tinzaparin group. Our population intent-to-treat included 65/70 patients, 32 of these received Standard heparin and 33 received Tinzaparin. The experimental intervention was administered for a maximum of 30 days and all the subjects were followed up for 90 days. The events were documented objectively with a venogram or Doppler ultrasonography by the end of the 30 days following the catheter installation. The incidence of catheter-related venous thrombosis (CRVT) during 30 days of instillation is 14,39/1000 catheter-days (CI 95%:[9,0;19,79]/1000 catheter-days or 41.5% (27/65). The incidence of symptomatic upper extremity deep venous thrombosis (DVT) during the observation period of 90 days is 0,41/1000 catheter-days (CI 95%:[0,08;0,81]/1000 catheter-days or 3% (2/65). We did not observe any difference in the frequency of CRVT or DVT between the two groups. We can not conclude that either Standard heparin or Tinzaparin is more effective in the prevention of CRVT in our population.

Nous avons mené une étude prospective randomisée dans le but de comparer l'effet de l'irrigation du cathéter de type PICC avec deux types d'anticoagulants: Héparine standard et Tinzaparine, une héparine de faible poids moléculaire. Notre étude s'adresse aux patients de la clinique externe d'oncologie de l'hôpital Maisonneuve-Rosemont. Entre début Mai 2005 et Mars 2008, nous avons recruté 131 patients dont 70 ont été randomisés. Parmi les 61 patients exclus, 23 n'ont pas rencontré les critères d'inclusion, 30 ont refusé de participer et 8 ne sont pas inclus pour d'autres raisons. Sur les 70, 36 sujets sont randomisés dans le groupe Héparine standard et 34 dans le groupe Tinzaparine. La population en intention de traiter comprend 65 sujets dont 32 dans le groupe Héparine standard et 33 dans le groupe Tinzaparine. Le médicament a été administré pendant un mombre maximal de 30 jours et les sujets ont été suivis pendant 90 jours. La thrombose veineuse associée au cathéter (TVAC) a été objectivée par une phlébographie ou une échographie-Doppler à la fin de la période de 30 jours suivant l'installation du cathéter. L'incidence de la TVAC sur 30 jours est de 14,39 par 1000 cathéter-jours (IC à 95%:[9,0;19,79]/1000 cathéter-jours ou 41,5% (27/65). L'incidence de la thrombose veineuse profonde (TVP) symptômatique du membre supérieur sur la période de suivi de 90 jours est de 0,41 par 1000 cathéter-jours (IC à 95%:[0,08;0,81]/1000 cathéter-jours ou 3% (2/65). Nous n'avons observé aucune différence entre les deux groupes par rapport à la fréquence de la TVAC ni de la TVP. Nous ne pouvons conclure à une différence dans l'efficacité de la Tinzaparine par rapport à l'Héparine standard dans la prévention de la TVAC. / Our prospective, randomized study aims at comparing the effectiveness of two types of heparin used for the instillation of peripherally inserted central catheter (PICC): Standard heparin and Tinzaparin, a low molecular weight heparin. We recruited patients from the ambulatory center of Maisonneuve-Rosemont hospital. Between the beginning of May 2005 and March 2008, 131 patients were enrolled. Of 61 patients excluded, 23 did not satisfy the inclusion criteria, 30 refused to participate and 8 were not enrolled for other reasons. Seventy patients were randomized into two groups, 36 in the Standard heparin group and 34 in the Tinzaparin group. Our population intent-to-treat included 65/70 patients, 32 of these received Standard heparin and 33 received Tinzaparin. The experimental intervention was administered for a maximum of 30 days and all the subjects were followed up for 90 days. The events were documented objectively with a venogram or Doppler ultrasonography by the end of the 30 days following the catheter installation. The incidence of catheter-related venous thrombosis (CRVT) during 30 days of instillation is 14,39/1000 catheter-days (CI 95%:[9,0;19,79]/1000 catheter-days or 41.5% (27/65). The incidence of symptomatic upper extremity deep venous thrombosis (DVT) during the observation period of 90 days is 0,41/1000 catheter-days (CI 95%:[0,08;0,81]/1000 catheter-days or 3% (2/65). We did not observe any difference in the frequency of CRVT or DVT between the two groups. We can not conclude that either Standard heparin or Tinzaparin is more effective in the prevention of CRVT in our population.