Increased generation of platelet-derived microparticles following percutaneous transluminal coronary angioplasty

Platelet-derived microparticles (PMPs) which are produced during platelet activation contribute to coagulation1 and bind to traumatized endothelium in an animal model2. Such endothelial injury occurs during percutaneous transluminal coronary angioplasty (PTCA), a procedure which restores the diameter of occluded coronary arteries using balloon inflations. However, re-occlusions subsequently develop in 20-25% of patients3, although this is limited by treatment with anti-platelet glycoprotein IIb/IIIa receptor drugs such as abciximab4. However, abciximab only partially decreases the need for revascularisation5, and therefore other mechanisms appear to be involved. As platelet activation occurs during PTCA, it is likely that PMPs may be produced and contribute to restenosis. This study population consisted of 113 PTCA patients, of whom 38 received abciximab. Paired peripheral arterial blood samples were obtained from the PTCA sheath: 1) following heparinisation (baseline); and 2) subsequent to all vessel manipulation (post-PTCA). Blood was prepared with an anti-CD61 (glycoprotein IIIa) fluorescence conjugated antibody to identify PMPs using flow cytometry, and PMP results expressed as a percentage of all CD61 events. The level of PMPs increased significantly from baseline following PTCA in the without abciximab group (paired t test, P=0.019). However, there was no significant change in the level of PMPs following PTCA in patients who received abciximab. Baseline clinical characteristics between patient groups were similar, although patients administered abciximab had more complex PTCA procedures, such as increased balloon inflation pressures (ANOVA, P=0.0219). In this study, we have clearly demonstrated that the level of CD61-positive PMPs increased during PTCA. This trend has been demonstrated previously, although a low sample size prevented statistical significance being attained6. The results of our work also demonstrate that there was no increase in PMPs after PTCA with abiciximab treatment. The increased PMPs may adhere to traumatized endothelium, contributing to re-occlusion of the arteries, but this remains to be determined. References: (1) Holme PA, Brosstad F, Solum NO. Blood Coagulation and Fibrinolysis. 1995;6:302-310. (2) Merten M, Pakala R, Thiagarajan P, Benedict CR. Circulation. 1999;99:2577-2582. (3) Califf RM. American Heart Journal.1995;130:680-684. (4) Coller BS, Scudder LE. Blood. 1985;66:1456-1459. (5) Topol EJ, Califf RM, Weisman HF, Ellis SG, Tcheng JE, Worley S, Ivanhoe R, George BS, Fintel D, Weston M, Sigmon K, Anderson KM, Lee KL, Willerson JT on behalf of the EPIC investigators. Lancet. 1994;343:881-886. (6) Scharf RE, Tomer A, Marzec UM, Teirstein PS, Ruggeri ZM, Harker LA. Arteriosclerosis and Thrombosis. 1992;12:1475-87.

Nonlinear container ship model for the study of parametric roll resonance

Parametric roll is a critical phenomenon for ships, whose onset may cause roll oscillations up to +-40 degrees, leading to very dangerous situations and possibly capsizing. Container ships have been shown to be particularly prone to parametric roll resonance when they are sailing in moderate to heavy head seas. A Matlab/Simulink parametric roll benchmark model for a large container ship has been implemented and validated against a wide set of experimental data. The model is a part of a Matlab/Simulink Toolbox (MSS, 2007). The benchmark implements a 3rd-order nonlinear model where the dynamics of roll is strongly coupled with the heave and pitch dynamics. The implemented model has shown good accuracy in predicting the container ship motions, both in the vertical plane and in the transversal one. Parametric roll has been reproduced for all the data sets in which it happened, and the model provides realistic results which are in good agreement with the model tank experiments.

Manoeuvring control of underactuated surface vessels using manifold regulation for Port-Hamiltonian systems

This paper considers the manoeuvring of underactuated surface vessels. The control objective is to steer the vessel to reach a manifold which encloses a waypoint. A transformation of configuration variables and a potential field are used in a Port-Hamiltonian framework to design an energy-based controller. With the proposed controller, the geometric task associated with the manoeuvring problem depends on the desired potential energy (closed-loop) and the dynamic task depends on the total energy and damping. Therefore, guidance and motion control are addressed jointly, leading to model-energy-based trajectory generation.

Anti-wind-up designs for dynamic positioning of marine vehicles with control allocation

This paper presents a framework for the design of a joint motion controller and a control allocation strategy for dynamic positioning of marine vehicles. The key aspects of the proposed designs are a systematic approach to deal with actuator saturation and to inform the motion controller about saturation. The proposed system uses a mapping that translates the actuator constraint sets into constraint sets at the motion controller level. Hence, while the motion controller addresses the constraints, the control allocation algorithm can solve an unconstrained optimisation problem. The constrained control design is approached using a multivariable anti-wind-up strategy for strictly proper controllers. This is applicable to the implementation of PI and PID type of motion controllers.

Stabilization of parametric roll resonance with active u-tanks via Lyapunov control design

Parametric ship roll resonance is a phenomenon where a ship can rapidly develop high roll motion while sailing in longitudinal waves. This effect can be described mathematically by periodic changes of the parameters of the equations of motion, which lead to a bifurcation. In this paper, the control design of an active u-tank stabilizer is carried out using Lyapunov theory. A nonlinear backstepping controller is developed to provide global exponential stability of roll. An extension of commonly used u-tank models is presented to account for large roll angles, and the control design is tested via simulation on a high-fidelity model of a vessel under parametric roll resonance.

Art spaces in community and economic development : connections to neighborhoods, artists, and the cultural economy

There is growing interest in the arts in community and economic development, yet little research examines the dynamics of community-based arts institutions to inform urban planning and policy. Drawing on interviews with participants and organizers of small and midsized art spaces, the study explores the factors that influence their involvement in neighborhood revitalization and outreach, support for artistic communities, and efforts to build bridges to commercial cultural sectors. Art spaces function as a conduit for building social networks that contribute to both community revitalization and artistic development. But issues pertaining to the location, organization, and management of art spaces may limit their community and economic development potential. The article concludes with proposals to craft stronger arts-based community and economic development programs.

Creative expression as the objective in video games

This study explores the idea of video games where the players are not just allowed to express themselves creatively, but are challenged to do so and are judged based on the quality of their creative expression. The outcome of the research is a series of six games which comment on this idea. The study also raises further questions regarding how current video games are constructed and designed in comparison with non-computer games, and invites a further evolution of the craft of video game design in a direction that focuses more on interpreting and reacting to what the player is doing.

We need to talk (denim workshop)

A collaborative, participatory denim craft station installed by the LEVEL feminist collective in the Q[ARI] Project - Artist-Run Initiatives exhibition, at the Griffith University Art Gallery in 2013. The exhibition was funded by the Queensland Government through Arts Queensland, and featured seven artist-run-initiatives from Brisbane.

Q&A : Christy Dena

Dr. Christy Dena is a noted academic and transmedia writer, experience designer, and director whose work includes the 2011 Digital Emmy-nominated Conspiracy for Good and The Hunt for Cisco. Dena is currently working on AUTHENTIC IN ALL CAPS, an online comedy/drama. Q: How did you get into transmedia? Q: What would you recommend that transmedia creators learn about to improve their craft? Q: What are the most important things to keep in mind when you’re designing an interactive element...

Development of an electronic role-play assessment initiative in bioscience for nursing students

Devising authentic assessments for subjects with large enrolments is a challenge. This study describes an electronic role-play assessment for approximately 600 first-year nursing students to learn and apply pathophysiology (bioscience) concepts to nursing practice. Students used Microsoft Office PowerPoint® to prepare electronic role-plays both between a nurse and patient, and between two nurses, thus simulating workplace scenarios. Student feedback demonstrated that respondents found this assessment useful for learning pathophysiology, and for applying pathophysiology to a nursing clinical setting. This electronic presentation circumvented issues associated with a traditional oral presentation such as embarrassment and logistics of scheduling groups, and rated well with students of non-English speaking background. The electronic role-play assessment initiative encouraged students to apply their bioscience knowledge to a clinical setting, and allowed students to conceptualise the importance of bioscience within both the nursing degree and the profession.

Advances in gyro-stabilisation of vessel roll motion

The use of gyro-dynamic forces to counteract the wave-induced roll motion of marine vessels in a seaway was proposed over 100 years ago. These early systems showed a remarkable performance, reporting roll reductions of up to 95% in some sailing conditions. Despite this success, further developments were not pursued since the systems were unable to provide acceptable performance over an extended envelope of sailing and environmental conditions, and the invention of fin roll stabilisers provided a satisfactory alternative. This has been attributed to simplistic controls, heavy drive systems, and large structural mass required to withstand the loads given the low strength materials available at the time. Today, advances in material strength, bearings, motor technology and mechanical design methods, together with powerful signal processing algorithms, has resulted in a revitalized interest in gyro-stabilisers for ships. Advanced control systems have enabled optimisation of restoring torques across a range of wave environments and sailing conditions through adaptive control system design. All of these improvements have resulted in increased spinning speed, lower mass, and dramatically increased stabilising performance. This brief paper provides an overview of recent developments in the design and control of gyro-stabilisers of ship roll motion. In particular, the novel Halcyon Gyro-Stabilisers are introduced, and their performance is illustrated based on a simulation case study for a naval patrol vessel. Given the growing national and global interest in small combatants and patrol vessels, modem gyro-stabilisers may offer a significant technological contribution to the age old problem of comfort and mission operability on small ships, especially at loiter speeds.

Increased platelet-derived microparticles in the coronary circulation of percutaneous transluminal coronary angioplasty patients

Platelet-derived microparticles that are produced during platelet activation are capable of adhesion and aggregation. Endothelial trauma that occurs during percutaneous transluminal coronary angioplasty (PTCA) may support platelet-derived microparticle adhesion and contribute to development of restenosis. We have previously reported an increase in platelet-derived microparticles in peripheral arterial blood with angioplasty. This finding raised concerns regarding the role of plateletderived microparticles in restenosis, and therefore the aim of this study was to monitor levels in the coronary circulation. The study population consisted of 19 angioplasty patients. Paired coronary artery and sinus samples were obtained following heparinization, following contrast administration, and subsequent to all vessel manipulation. Platelet-derived microparticles were identified with an anti-CD61 (glycoprotein IIIa) fluorescence-conjugated antibody using flow cytometry. There was a significant decrease in arterial platelet-derived microparticles from heparinization to contrast administration (P 0.001), followed by a significant increase to the end of angioplasty (P 0.004). However, there was no significant change throughout the venous samples. These results indicate that the higher level of platelet-derived microparticles after angioplasty in arterial blood remained in the coronary circulation. Interestingly, levels of thrombin–antithrombin complexes did not rise during PTCA. This may have implications for the development of coronary restenosis post-PTCA, although this remains to be determined.

Increased generation of platelet-derived microparticles following percutaneous transluminal coronary angioplasty

Platelet-derived microparticles that are produced during platelet activation bind to traumatized endothelium. Such endothelial injury occurs during percutaneous transluminal coronary angioplasty. Approximately 20% of these patients subsequently develop restenosis, although this is improved by treatment with the anti-platelet glycoprotein IIb/IIIa receptor drug abciximab. As platelet activation occurs during angioplasty, it is likely that platelet-derived microparticles may be produced and hence contribute to restenosis. This study population consisted of 113 angioplasty patients, of whom 38 received abciximab. Paired peripheral arterial blood samples were obtained following heparinization and subsequent to all vessel manipulation. Platelet-derived microparticles were identified using an anti-CD61 (glycoprotein IIIa) fluorescence-conjugated antibody and flow cytometry. Baseline clinical characteristics between patient groups were similar. The level of platelet-derived microparticles increased significantly following angioplasty in the group without abciximab (paired t test, P 0.019). However, there was no significant change in the level of platelet-derived microparticles following angioplasty in patients who received abciximab, despite requiring more complex angioplasty procedures. In this study, we have demonstrated that the level of platelet-derived microparticles increased during percutaneous transluminal coronary angioplasty, with no such increase with abciximab treatment. The increased platelet-derived microparticles may adhere to traumatized endothelium, contributing to re-occlusion of the arteries, but this remains to be determined.

Development of an online role-play assessment initiative for nursing students in their bioscience studies

Devising assessment tasks for large units that embrace academic goals of authenticity and assessment variety can be a challenge. We developed an online Role-Play Assessment Initiative for first year nursing students in bioscience. Students responded to a case study by preparing two role-play dialogues: as a nurse with the patient, and between two nurses. The aims were to assess whether the students could: 1) understand the underlying disease process (pathophysiology) and relate it to clinical practice; 2) use language appropriate for lay and medical conversation; and 3) apply information using active learning. We conducted a student survey using quantitative questions (Likert scale: 1=strongly disagree to 5=strongly agree), and qualitative questions. 65 completed surveys were received. 80% of respondents agreed (includes agree or strongly agree) that it was a useful way to learn and understand pathophysiology of the case study. 86% agreed that it was useful to apply pathophysiology from lectures to a clinical setting. Overall, students found it enjoyable, which is beneficial for enhanced student engagement, and agreed that it allowed them to work well in a group (74% and 85%, respectively). Most qualitative suggestions for improvement related to group work, despite the encouraging response to group work in quantitative questions. Most positive comments surrounded different communication with a nurse compared with a patient. These results demonstrate that students developed deeper understanding of pathophysiology through active learning and were able to expand their nursing career skills during the role-play. Learning using role-play to simulate the workforce has fostered active learning.