Rate-limiting roles of the tenase complex of factors VIII and IX in platelet procoagulant activity and formation of platelet-fibrin thrombi under flow

The importance of factor Xa generation in thrombus formation has not been studied extensively so far. Here, we used mice deficient in either factor VIII or factor IX to determine the role of platelet-stimulated tenase activity in the formation of platelet-fibrin thrombi on collagen. With tissue factor present, deficiency in factor VIII or IX markedly suppressed thrombus growth, fibrin formation and platelet procoagulant activity (phosphatidylserine exposure). In either case, residual fibrin formation was eliminated in the absence of tissue factor. Effects of factor deficiencies were antagonized by supplementation of the missing coagulation factor. In wild-type thrombi generated under flow, phosphatidylserine-exposing platelets bound (activated) factor IX and factor X, whereas factor VIII preferentially co-localized at sites of von Willebrand factor binding. Furthermore, proteolytic activity of the generated activated factor X and thrombin was confined to the sites of phosphatidylserine exposure. With blood from a hemophilia A or B patient, the formation of platelet-fibrin thrombi was greatly delayed and reduced, even in the presence of high concentrations of tissue factor. A direct activated factor X inhibitor, rivaroxaban, added to human blood, suppressed both thrombin and fibrin formation. Together, these data point to a potent enforcement loop in thrombus formation due to factor X activation, subsequent thrombin and fibrin generation, causing activated factor X-mediated stimulation of platelet phosphatidylserine exposure. This implies that the factor VIII/factor IX-dependent stimulation of platelet procoagulant activity is a limiting factor for fibrin formation under flow conditions, even at high tissue factor concentrations

An organelle-specific protein landscape identifies novel diseases and molecular mechanisms

Contains fulltext : 158967.pdf (publisher's version ) (Open Access)Cellular organelles provide opportunities to relate biological mechanisms to disease. Here we use affinity proteomics, genetics and cell biology to interrogate cilia: poorly understood organelles, where defects cause genetic diseases. Two hundred and seventeen tagged human ciliary proteins create a final landscape of 1,319 proteins, 4,905 interactions and 52 complexes. Reverse tagging, repetition of purifications and statistical analyses, produce a high-resolution network that reveals organelle-specific interactions and complexes not apparent in larger studies, and links vesicle transport, the cytoskeleton, signalling and ubiquitination to ciliary signalling and proteostasis. We observe sub-complexes in exocyst and intraflagellar transport complexes, which we validate biochemically, and by probing structurally predicted, disruptive, genetic variants from ciliary disease patients. The landscape suggests other genetic diseases could be ciliary including 3M syndrome. We show that 3M genes are involved in ciliogenesis, and that patient fibroblasts lack cilia. Overall, this organelle-specific targeting strategy shows considerable promise for Systems Medicine

Monitoring in vitro thrombus formation with novel microfluidic devices

Cardiovascular disease is a major cause of mortality globally and is subject to ongoing research to improve clinical treatment. It is established that activation of platelets and coagulation are central to thrombosis, yet at different extents in the arterial and venous system. In vitro perfusion chamber technology has contributed significant knowledge on the function of platelets in the thrombotic process under shear conditions. Recent efforts to downscale this technique with a variety of microfluidic devices has opened new possibilities to study this process under precisely controlled flow conditions. Such microfluidic devices possess the capability to execute platelet function tests more quickly than current assays, while using small blood samples. Gradually becoming available to the clinic now, they may provide a new means to manage the treatment of cardiovascular diseases, although accurate validation studies still are missing. This review highlights the progress that has been made in monitoring aspects of thrombus formation using microfluidic devices

Monitoring in vitro thrombus formation with novel microfluidic devices

Cardiovascular disease is a major cause of mortality globally and is subject to ongoing research to improve clinical treatment. It is established that activation of platelets and coagulation are central to thrombosis, yet at different extents in the arterial and venous system. In vitro perfusion chamber technology has contributed significant knowledge on the function of platelets in the thrombotic process under shear conditions. Recent efforts to downscale this technique with a variety of microfluidic devices has opened new possibilities to study this process under precisely controlled flow conditions. Such microfluidic devices possess the capability to execute platelet function tests more quickly than current assays, while using small blood samples. Gradually becoming available to the clinic now, they may provide a new means to manage the treatment of cardiovascular diseases, although accurate validation studies still are missing. This review highlights the progress that has been made in monitoring aspects of thrombus formation using microfluidic devices

Multidisciplinary collaborative care for depressive disorder in the occupational health setting: Design of a randomised controlled trial and cost-effectiveness study

<p>Abstract</p> <p>Background</p> <p>Major depressive disorder (MDD) has major consequences for both patients and society, particularly in terms of needlessly long sick leave and reduced functioning. Although evidence-based treatments for MDD are available, they show disappointing results when implemented in daily practice. A focus on work is also lacking in the treatment of depressive disorder as well as communication of general practitioners (GPs) and other health care professionals with occupational physicians (OPs). The OP may play a more important role in the recovery of patients with MDD. Purpose of the present study is to tackle these obstacles by applying a collaborative care model, which has proven to be effective in the USA, with a focus on return to work (RTW). From a societal perspective, the (cost)effectiveness of this collaborative care treatment, as a way of transmural care, will be evaluated in depressed patients on sick leave in the occupational health setting.</p> <p>Methods/Design</p> <p>A randomised controlled trial in which the treatment of MDD in the occupational health setting will be evaluated in the Netherlands. A transmural collaborative care model, including Problem Solving Treatment (PST), a workplace intervention, antidepressant medication and manual guided self-help will be compared with care as usual (CAU). 126 Patients with MDD on sick leave between 4 and 12 weeks will be included in the study. Care in the intervention group will be provided by a multidisciplinary team of a trained OP-care manager and a consultant psychiatrist. The treatment is separated from the sickness certification. Data will be collected by means of questionnaires at baseline and at 3, 6, 9 and 12 months after baseline. Primary outcome measure is reduction of depressive symptoms, secondary outcome measure is time to RTW, tertiary outcome measure is the cost effectiveness.</p> <p>Discussion</p> <p>The high burden of MDD and the high level of sickness absence among people with MDD contribute to the relevance of this study. The intervention is an innovative approach, with trained OPs in a new role as care managers in the treatment of MDD. If this intervention proves to be cost-effective, implementation will be very relevant for individual patients as well as for society.</p> <p>Trial registration</p> <p>ISRCTN78462860</p