Atherosclerotic Plaque Adhesion Strength and its role in Plaque Rupture

Cardiovascular diseases are disorders affecting the blood vessels and the heart. According to the World Health Organization, cardiovascular diseases are one of the leading causes of death worldwide. They are responsible for over 17.1 million deaths per year worldwide, representing 31.5% of deaths 1, 2. Atherosclerosis, a chronic inflammatory disorder affecting large arteries, is the underlying cause of many cardiovascular diseases. Plaque rupture is a serious complication of advanced atherosclerosis, often leading to life-threatening clinical consequences such as myocardial infarction (heart attack) or stroke. 75% of newly developed myocardial infarction cases are caused by atherosclerotic plaque rupture. It affects approximately 1.1 million people in the USA per year, with a 40% fatality rate; 220,000 of these deaths occur without hospitalization. Over the past few decades, the mechanisms of atherosclerotic plaque progression and formation have been widely studied. However, due to the complexity of the process, plaque rupture mechanisms are still poorly understood. In this thesis, a novel hypothesis regarding mechanisms of plaque rupture is proposed. Specifically, we hypothesize that the adhesive strength of the bond between the plaque and the vascular wall is an important determinant of atherosclerotic plaque stability (resistance to rupture). We also expect adhesive strength to be a function of plaque composition and extracellular matrix (ECM) organization at the plaque-media interface. This proposed mode of rupture is called delamination or plaque peeling. Mouse plaque peeling experiments were very challenging and they needed time to be performed and validated. Thus, due to similarity of the experimental protocol, we used experimental data obtained on the dissection of human coronary artery specimens by Ying Wang3, and we created a numerical model to apply the cohesive zone technique to this problem. Arterial dissection is a rare but potentially fatal condition in which blood passes through the inner lining and between the layers of the arterial wall. It results in separation of the different layers, creating a false lumen in the process. The advantages to performing a primary study on arterial dissection were first to apply the cohesive zone models to a less complex problem than atherosclerosis. The innovative technical approach to measure the adhesive strength developed previously4,3, will be applied in this thesis to mice. It includes a micro-scale peel experiment protocol to measure adhesive strength of mouse atherosclerotic plaques during delamination from the underlying vessel wall. Our team at USC, as far as we know, was the first to perform these types of measurements on mice. The use of mice in our experiments presents the advantage that the extracellular matrix composition could be systematically changed using transgenic strains, altered diet, or drug treatments. Different mouse strains or models could then be used and the mechanical properties will be studied on each type. Another innovation of our work will involve application of a cohesive zone model to describe delamination behavior of atherosclerotic plaques under a range of physiological and pathophysiological conditions, using a 2D numerical model. While the cohesive zone approach has been widely used to model fracture mechanics in classic engineering materials, it was rarely applied to describe failure of atherosclerotic plaques. The study of plaque delamination by Leng et al. 20155 was designed to test the use of cohesive zones by implementing a specific traction separation law, assuming the parameter values of the behavior laws of the plaque and the cohesive zone using values from the literature. Innovation in our approach is to use a simple traction separation law to study the behavior of plaques and identifying their properties. Experimental results of delamination of the plaques were used in the definition of traction-separation laws of the cohesive zone

Webbapplikation för visualisering av statistik

Syna is one of the oldest credit bureau and they got access to large actual data from different authorities like Skatteverket, Kronofogden etc. With help from this actual data, Syna have a possibility to represent this data in a graphical way. The task for this thesis was to implement a web interface that represents the chosen data in a graphical diagram. A big part of this thesis was to analyze different ways to represent this data. Also how to dynamically store the result in a MySQL databases to optimize the performance of the web application. The thesis had some requests from Syna. These requests affected performance, usability and implementation and were the main concern of this thesis. The web interface main task is to represent the data that came from the different databases that Syna beholds. The retrieval of the data came from the program Softbool’s Boolware and this program is used regularly in Syna’s network. The result from these searches where then dynamically stored in a MySQL databases. The purpose of this web interface is that it should act like a tool for newsletter companies, universities, and companies etc., to see the relations of the information that affects their operations. This rapport includes the process of the thesis, methods, methodologies and models used under the thesis progress

Tracheal agenesis as a rare cause of difficult intubation in a newborn with respiratory distress: a case report

<p>Abstract</p> <p>Introduction</p> <p>Tracheal agenesis is a very rare congenital airway anomaly. It may pose a great challenge to the first attending physician both in diagnosis and in establishing the airway during the first day of life.</p> <p>Case presentation</p> <p>We report a newborn Malay baby boy with trachea agenesis (type III by Floyd's classification) who presented with severe respiratory distress immediately after birth. Clinical diagnosis in this case was not straightforward, as it started with difficulty in intubation followed by an unsuccessful emergency tracheostomy in the neonatal intensive care unit. Urgent surgical neck exploration with endoscopic examination in the general operating theatre revealed the final diagnosis. The authors present a short description of the embryopathology and diagnostic criteria of the abnormality.</p> <p>Conclusion</p> <p>We hope this case presentation will be valuable in increasing the awareness of physicians about this rare cause of tracheal obstruction or difficult intubation.</p

An experimental Staphylococcus aureus carriage and decolonization model in rhesus macaques (Macaca mulatta)

Our human model of nasal colonization and eradication of S. aureus is limited by safety issues. As rhesus macaques are closely related to humans and natural hosts for S. aureus, we developed an experimental decolonization and inoculation protocol in these animals. Animals were screened for nasal carriage of S. aureus and 20 carriers were selected. Decolonization was attempted using nasal mupirocin (10 animals) or mupirocin plus trimethoprim/ sulfadiazine intramuscularly (10 animals) both once daily for 5 days, and checked by followup cultures for 10 weeks. Intranasal inoculation was performed with S. aureus strain 8325–4 in culture-negative animals. 11/20 animals, of which 5 received mupirocin and 6 the combination treatment, became culture-negative for S. aureus for 10 weeks and these 11 animals were subsequently inoculated. Swabs were taken once a week for 5 weeks to test for the presence of the inoculated strain. In 3 animals, strain 8325–4 was cultured from the nose 1 week after inoculation, indicating short-term survival of this strain only, a finding similar to that previously found in our human model. These data demonstrate that rhesus macaques may constitute a relevant animal model to perform S. aureus eradication and inoculation studies with relatively limited invasive handling of the animals

Isolated congenital tracheal stenosis in a preterm newborn

Severe tracheal stenosis, resulting in functional atresia of the trachea is a rare congenital malformation with an estimated occurrence of two in 100,000 newborns. If no esophagotracheal fistula is present to allow for spontaneous breathing, this condition is usually fatal. We report on a male infant born at 32 weeks of gestation. The patient presented with respiratory distress immediately after delivery due to severe congenital tracheal stenosis resulting in functional atresia of the trachea. Endotracheal intubation failed and even emergency tracheotomy did not allow ventilation of the patient lungs. The patient finally succumbed to prolonged hypoxia due to functional tracheal atresia. The etiology of tracheal atresia and tracheal stenosis is still unclear, but both conditions are frequently combined with other anomalies of the VACTERL (vertebral anomalies, anal atresia, cardiovascular anomalies, tracheoesophageal fistula, esophageal atresia, renal/radial anomalies and limb defects) and TACRD (tracheal agenesis, cardiac, renal and duodenal malformations) association. Conclusion Successful treatment of severe congenital tracheal stenosis and tracheal atresia depends on either prenatal diagnosis or recognition of this condition immediately after birth to perform tracheotomy without delay. Nevertheless, despite any efforts, the therapeutical results of severe tracheal stenosis and tracheal atresia are still unsatisfactory

Social identity and the recognition of creativity in groups

Authors' draft; final version published in British Journal of Social Psychology, 45, 479-497This paper develops an analysis of creativity that is informed by the social identity approach. Two studies are reported that support this analysis. Study 1 (N=73) manipulated social identity salience and the content of group norms. The group norm was either conservative (i.e. promoted no change) or progressive (i.e. promoted change). When social identity was salient and the group norm was conservative, a non-novel proposal was perceived to be more creative. Study 2 (N=63) manipulated social norms and identity relevance. Results showed that while social norms influenced perceptions of creativity, identity relevance influenced positivity but not perceptions of creativity. These findings support the idea that perceptions of creativity are grounded in the normative content of group membership and self-categorization processes

Modelling of redox flow battery electrode processes at a range of length scales : a review

In this article, the different approaches reported in the literature for modelling electrode processes in redox flow batteries (RFBs) are reviewed. RFB models vary widely in terms of computational complexity, research scalability and accuracy of predictions. Development of RFB models have been quite slow in the past, but in recent years researchers have reported on a range of modelling approaches for RFB system optimisation. Flow and transport processes, and their influence on electron transfer kinetics, play an important role in the performance of RFBs. Macro-scale modelling, typically based on a continuum approach for porous electrode modelling, have been used to investigate current distribution, to optimise cell design and to support techno-economic analyses. Microscale models have also been developed to investigate the transport properties within porous electrode materials. These microscale models exploit experimental tomographic techniques to characterise three-dimensional structures of different electrode materials. New insights into the effect of the electrode structure on transport processes are being provided from these new approaches. Modelling flow, transport, electrical and electrochemical processes within the electrode structure is a developing area of research, and there are significant variations in the model requirements for different redox systems, in particular for multiphase chemistries (gas–liquid, solid–liquid, etc.) and for aqueous and non-aqueous solvents. Further development is essential to better understand the kinetic and mass transport phenomena in the porous electrodes, and multiscale approaches are also needed to enable optimisation across the relevent length scales