High resolution 3-Dimensional imaging of the human cardiac conduction system from microanatomy to mathematical modeling

Cardiac arrhythmias and conduction disturbances are accompanied by structural remodelling of the specialised cardiomyocytes known collectively as the cardiac conduction system. Here, using contrast enhanced micro-computed tomography, we present, in attitudinally appropriate fashion, the first 3-dimensional representations of the cardiac conduction system within the intact human heart. We show that cardiomyocyte orientation can be extracted from these datasets at spatial resolutions approaching the single cell. These data show that commonly accepted anatomical representations are oversimplified. We have incorporated the high-resolution anatomical data into mathematical simulations of cardiac electrical depolarisation. The data presented should have multidisciplinary impact. Since the rate of depolarisation is dictated by cardiac microstructure, and the precise orientation of the cardiomyocytes, our data should improve the fidelity of mathematical models. By showing the precise 3-dimensional relationships between the cardiac conduction system and surrounding structures, we provide new insights relevant to valvar replacement surgery and ablation therapies. We also offer a practical method for investigation of remodelling in disease, and thus, virtual pathology and archiving. Such data presented as 3D images or 3D printed models, will inform discussions between medical teams and their patients, and aid the education of medical and surgical trainees

Evaluation of the impact of interdisciplinarity in cancer care

<p>Abstract</p> <p>Background</p> <p>Teamwork is a key component of the health care renewal strategy emphasized in Quebec, elsewhere in Canada and in other countries to enhance the quality of oncology services. While this innovation would appear beneficial in theory, empirical evidences of its impact are limited. Current efforts in Quebec to encourage the development of local interdisciplinary teams in all hospitals offer a unique opportunity to assess the anticipated benefits. These teams working in hospital outpatient clinics are responsible for treatment, follow-up and patient support. The study objective is to assess the impact of interdisciplinarity on cancer patients and health professionals.</p> <p>Methods/Design</p> <p>This is a quasi-experimental study with three comparison groups distinguished by intensity of interdisciplinarity: strong, moderate and weak. The study will use a random sample of 12 local teams in Quebec, stratified by intensity of interdisciplinarity. The instrument to measure the intensity of the interdisciplinarity, developed in collaboration with experts, encompasses five dimensions referring to aspects of team structure and process. Self-administered questionnaires will be used to measure the impact of interdisciplinarity on patients (health care utilization, continuity of care and cancer services responsiveness) and on professionals (professional well-being, assessment of teamwork and perception of teamwork climate). Approximately 100 health professionals working on the selected teams and 2000 patients will be recruited. Statistical analyses will include descriptive statistics and comparative analysis of the impact observed according to the strata of interdisciplinarity. Fixed and random multivariate statistical models (multilevel analyses) will also be used.</p> <p>Discussion</p> <p>This study will pinpoint to what extent interdisciplinarity is linked to quality of care and meets the complex and varied needs of cancer patients. It will ascertain to what extent interdisciplinary teamwork facilitated the work of professionals. Such findings are important given the growing prevalence of cancer and the importance of attracting and retaining health professionals to work with cancer patients.</p

Questioning Quill

The physical presence rule of Quill Corp. v. North Dakota is under increasing attack from the “Kill Quill” movement — a consortium of state tax administrators, industry leaders, and academics opposed to the decision. The physical presence rule prohibits states from requiring many out-of-state vendors to collect taxes on goods sold into the states. Kill Quill states have grown increasingly aggressive, and litigation is well underway in South Dakota and Alabama over those states’ direct disregard for the rule. As a petition to the Supreme Court for certiorari grows closer, the case for overturning the physical presence rule remains cloudy.Technology and the economy have changed in the 25 years since Quill was decided, but are these changes enough to convince the Court to reexamine the rule? This Article argues that more will be needed; attention must be drawn to the analytical gaps in the cases endorsing the physical presence rule. These cases have failed to explain the basis for requiring any connection between a taxing state and a taxpayer under the Commerce Clause (under which the physical presence rule originates) and have reflexively blended together the substance of sales taxes and use taxes. Through unpacking these issues, the Article exposes principles to guide the development of fundamentally sound rules for sales and use tax jurisdiction

A Detailed 3D Model of the Rabbit Right Atrium Including the Sinoatrial Node, Atrioventricular Node, Surrounding Blood Vessels and Valves

We used multiple techniques to generate a threedimensional anatomical model of the rabbit right atrium with the sinoatrial node (SAN) and atrioventricular node (AVN). The model includes the right atrium, SAN, AVN, part of right ventricle, aorta with aortic valve, superior vena cava, inferior vena cava, coronary sinus, tricuspid valve, part of mitral valve, fossa ovalis and central fibrous body. The tendon of Todaro and right and left sinoatrial ring bundles were highlighted as landmarks. 1

Expression of Kir2.1 and Kir6.2 transgenes under the control of the alpha-MHC promoter in the sinoatrial and atrioventricular nodes in transgenic mice

Kir2.1 and Kir6.2 are ion channel subunits partly responsible for the background inward rectifier and ATP-sensitive K+ currents (IK1 and IKATP) in the heart. Very little is known about how the distribution of ion channel subunits is controlled. In this study, we have investigated the expression (at protein and mRNA levels) of GFP-tagged Kir2.1 and Kir6.2 transgenes under the control of the α-MHC promoter in the sinoatrial node (SAN), atrioventricular node (AVN), His bundle and working myocardium of transgenic mice. After dissection, serial 10-μm cryosections were cut. Histological staining was carried out to identify tissues, confocal microscopy was carried out to map the distribution of the GFP-tagged ion channel subunits and in situ hybridization was carried out to map the distribution of corresponding mRNAs. We demonstrate heterologous expression of the ion channel subunits in the working myocardium, but not necessarily in the SAN, AVN or His bundle; the distribution of the subunits does not correspond to the expected distribution of α-MHC. Both protein and mRNA expression does, however, correspond to the expected distributions of native Kir6.2 and Kir2.1 in the SAN, AVN, His bundle and working myocardium. The data demonstrate novel transcriptional and/or post-transcriptional control of ion channel subunit expression and raise important questions about the control of regional expression of ion channels