China 
Africa 
Explore chapters and articles related to this topic
Role of Streptokinase as a Thrombolytic Agent for Medical Applications
Published in Pankaj Bhatt, Industrial Applications of Microbial Enzymes, 2023
Hamza Rafeeq, Muhammad Anjum Zia, Asim Hussain, Ayesha Safdar, Muhammad Bilal, Hafiz M. N. Iqbal
Thrombosis is blood clot formation in the blood vessels, and this is actually the result of an imbalance of hemostasis and its inhibitors (Rizzoli et al., 2013). Changes in the blood vessels result in thrombosis, especially if the blood flow is slow (Kikkert et al., 2014). Atherosclerosis is due to changes in blood vessels. The plaques are protrusions in blood vessels, and these plaques are made up of lipids and collagens made up of smooth muscles (Tadayon et al., 2015). Different cells, such as free fatty acids, cholesterol, and scar tissues present in the arterial walls, make the arteries constrict, making it difficult for blood to flow to the heart. Chest pain is caused by slowed blood flow, and heart attack results from complete blockage of blood. And the most prominent cause of death in the developed countries is thrombosis. Forty-five percent of total deaths are due to vascular diseases in the United States (Ali et al., 2016). Lifestyle and diet changes prevent thrombosis. High plasma lipid levels are due to an imbalanced diet, lack of physical activity, high blood pressure, and cigarette smoking (Ali et al., 2016). Figure 14.1 represents the mechanism of thrombus formation in a circulatory system.
Elements of Continuum Mechanics
Published in Clement Kleinstreuer, Biofluid Dynamics, 2016
Thrombosis is the formation of a blood clot, called a thrombus, inside an artery or vein. Thrombosis develops by the same mechanisms that control hemostasis, i.e., the clotting system which prevents blood loss in the event of vessel injury. A thrombus is primarily composed of platelets and red blood cells bound together by molecules in the cell membrane of the platelets, called membrane glycoproteins (GPs), by other proteins in the blood or inside the platelets, and by a network of polymerized plasma protein called fibrin (Colman et al., 1994). An arterial thrombus, as found in high shear regions, is composed primarily of platelets, with some fibrin and trapped red blood cells, which are typically found distal to the plateletrich part of the thrombus. As mentioned, an arterial thrombus is usually found superimposed on an atherosclerotic plaque which has fissured (or ruptured) to expose subendothelium plaque components to the blood. Arterial thrombosis may also develop on artificial surfaces such as vascular grafts, heart valves, and stents, as well as in aneurysms or injured arteries.
Biomimetic Approaches for the Design and Development of Multifunctional Bioresorbable Layered Scaffolds for Dental Regeneration
Published in Vincenzo Guarino, Marco Antonio Alvarez-Pérez, Current Advances in Oral and Craniofacial Tissue Engineering, 2020
Campodoni Elisabetta, Dozio Samuele Maria, Mulazzi Manuela, Montanari Margherita, Montesi Monica, Panseri Silvia, Sprio Simone, Tampieri Anna, Sandri Monica
The inability of most tissues and organs in adult humans to regenerate after damage, has been a serious problem that affects doctors, dentists and, of course, patients. Among them, the tooth is a complex organ made of highly mineralized tissues (alveolar bone, cement, dentin, enamel) and non-mineralized periodontal ligament (PDL), which connects the alveolar bone to the cement and guarantees the functionality and stability of the tooth. Dental diseases are extremely widespread all over the world, such as periodontitis, pulpitis and others that require a reconstruction of the dental apparatus. Biocompatible prosthetic devices have provided options in many cases helping millions of people, but the body’s reaction to these devices is far from ideal. Complications including thrombosis, infections, ongoing inflammatory reactions, excessive fibrosis, impaired functions, mobilization and extrusion, are problematic for patients and expensive for the healthcare system. In dentistry, titanium and bioceramics implants or materials such as stainless steel, silicone rubber and poly methacrylate are widely used for the reconstruction of dental apparatus. However, the failure of these devices due to healing problems, infection and overload problems is well recognized Nowadays, the accepted standard for defining success in dental implants, has become a phenomenon called osseointegration, associated to a concept of years of reliable function rather than device life. The challenge for osseointegration is the stimulation of the right response in the surrounding tissue, which is strictly related to the material and the implant chemistry and features.
Modeling the effect of blood vessel bifurcation ratio on occlusive thrombus formation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Hari Hara Sudhan Lakshmanan, Joseph J. Shatzel, Sven R. Olson, Owen J.T. McCarty, Jeevan Maddala
Clinical decision making when it comes to anticoagulation is often dichotomous; for example, duration of anticoagulation for VTE is primarily dependent on whether the event was provoked by a transient risk factor or not, with “unprovoked” VTE carrying a high risk of recurrent thrombosis and typically mandating lifelong anticoagulation (Kearon et al. 2012). Arterial thrombosis can be treated with antiplatelet agents or anticoagulants depending on the thrombus location and etiology (Amsterdam et al. 2014). While select therapies may improve outcomes in a subset of patients with thrombosis, there remains an unmet need to better stratify patients who will benefit from the available therapies, balancing safety with efficacy. More granular risk stratification could conceivably be aided by mathematical models that could predict occlusion in microvessels and imaging to visualize microvascular thrombi (Leiderman and Fogelson 2014). Vessel geometry and local hemodynamics are factors that contribute to initiation of thrombus formation leading to vessel occlusion. Bifurcations present a complex hemodynamic environment with unique properties that may specifically predispose these regions to thrombosis (Otero-Cacho et al. 2018). Results from microfluidic studies that involve multiple bifurcations demonstrate the importance of geometry in the kinetics of thrombus formation (Zilberman-Rudenko et al. 2017). Clinically, large vessel bifurcations are common sites of arterial plaques and thrombosis, predisposing patients to stroke in the case of carotid artery bifurcation (Morbiducci et al. 2016).
In Vitro models for thrombogenicity testing of blood-recirculating medical devices
Published in Expert Review of Medical Devices, 2019
Evaluating the thrombosis potential of medical devices is an essential part of their development. Currently, a combination of in vitro and in vivo thrombosis models are used to predict the clinical thrombosis outcomes of such devices. In vitro studies can be categorized into two subsets: static models and dynamic models. Each of these models offer distinct advantages and disadvantages for probing the thrombosis potential of surfaces and devices. ISO 10993–4 offers a selection of testable markers for thrombosis, but offers little guidance on their use in static tests and dynamic flow loops. The result is that in vitro testing is underutilized in the field of blood-recirculating medical devices. When in vitro thrombosis testing is done, it is highly unstandardized. Flow loops use varying materials, shear rates, and physical features and test for thrombosis using a variety of molecular markers, most commonly hemolysis. The clinical relevance of each individual flow loop is not established, leaving most thrombosis testing to in vivo testing. While current guidelines may suffice for small blood contacting devices, the next generation of medical devices, wearable and artificial implantable organs, are being challenged with high volumes of blood, flow rates, and prolonged exposure to blood. Blood-recirculating medical devices such as mechanical circulatory support, ECMO systems, and hemodialysis equipment require a more thorough investigation of thrombosis in a benchtop setting as they advance into wearable and implantable devices.
Gelatin coating promotes in situ endothelialization of electrospun polycaprolactone vascular grafts
Published in Journal of Biomaterials Science, Polymer Edition, 2021
Yuehao Xing, Yongquan Gu, Lianrui Guo, Jianming Guo, Zeqin Xu, Yonghao Xiao, Zhiping Fang, Cong Wang, Zeng-Guo Feng, Zhonggao Wang
The anticoagulant property is crucial to prevent thrombosis. Our previous study showed that anticoagulant properties of PCL grafts improved after heparin modification [28]. Therefore, heparin was immobilized covalently on the gelatin to enhance the anticoagulant property of the grafts. With the release of heparin, the heparin content may not be sufficient to prevent thrombosis. Therefore, we studied the effect of different heparin content on the prevention of thrombosis. The results showed that no thrombus was found in the GP-H grafts and the P-H grafts. Therefore, low heparin content is sufficient for thrombosis prevention.