Contrast-enhanced micro-CT imaging in murine carotid arteries : a new protocol for computing wall shear stress

Background: Wall shear stress (WSS) is involved in the pathophysiology of atherosclerosis. The correlation between WSS and atherosclerosis can be investigated over time using a WSS-manipulated atherosclerotic mouse model. To determine WSS in vivo, detailed 3D geometry of the vessel network is required. However, a protocol to reconstruct 3D murine vasculature using this animal model is lacking. In this project, we evaluated the adequacy of eXIA 160, a small animal contrast agent, for assessing murine vascular network on micro-CT. Also, a protocol was established for vessel geometry segmentation and WSS analysis. Methods: A tapering cast was placed around the right common carotid artery (RCCA) of ApoE(-/-) mice (n = 8). Contrast-enhanced micro-CT was performed using eXIA 160. An innovative local threshold-based segmentation procedure was implemented to reconstruct 3D geometry of the RCCA. The reconstructed RCCA was compared to the vessel geometry using a global threshold-based segmentation method. Computational fluid dynamics was applied to compute the velocity field and WSS distribution along the RCCA. Results: eXIA 160-enhanced micro-CT allowed clear visualization and assessment of the RCCA in all eight animals. No adverse biological effects were observed from the use of eXIA 160. Segmentation using local threshold values generated more accurate RCCA geometry than the global threshold-based approach. Mouse-specific velocity data and the RCCA geometry generated 3D WSS maps with high resolution, enabling quantitative analysis of WSS. In all animals, we observed low WSS upstream of the cast. Downstream of the cast, asymmetric WSS patterns were revealed with variation in size and location between animals. Conclusions: eXIA 160 provided good contrast to reconstruct 3D vessel geometry and determine WSS patterns in the RCCA of the atherosclerotic mouse model. We established a novel local threshold-based segmentation protocol for RCCA reconstruction and WSS computation. The observed differences between animals indicate the necessity to use mouse-specific data for WSS analysis. For our future work, our protocol makes it possible to study in vivo WSS longitudinally over a growing plaque

Vortex microavalanches in superconducting Pb thin films

Local magnetization measurements on 100 nm type-II superconducting Pb thin films show that flux penetration changes qualitatively with temperature. Small flux jumps at the lowest temperatures gradually increase in size, then disappear near T = 0.7Tc. Comparison with other experiments suggests that the avalanches correspond to dendritic flux protrusions. Reproducibility of the first flux jumps in a decreasing magnetic field indicates a role for defect structure in determining avalanches. We also find a temperature-independent final magnetization after flux jumps, analogous to the angle of repose of a sandpile.Comment: 6 pages, 5 figure

CMV retinitis screening and treatment in a resource-poor setting: three-year experience from a primary care HIV/AIDS programme in Myanmar

Cytomegalovirus retinitis is a neglected disease in resource-poor settings, in part because of the perceived complexity of care and because ophthalmologists are rarely accessible. In this paper, we describe a pilot programme of CMV retinitis management by non-ophthalmologists. The programme consists of systematic screening of all high-risk patients (CD4 <100 cells/mm3) by AIDS clinicians using indirect ophthalmoscopy, and treatment of all patients with active retinitis by intravitreal injection of ganciclovir. Prior to this programme, CMV retinitis was not routinely examined for, or treated, in Myanmar

Cognitive Behavioral Therapy Versus Usual Care Before Bariatric Surgery:One-Year Follow-Up Results of a Randomized Controlled Trial

Background Although early results of bariatric surgery are beneficial for most patients, some patients regain weight later. Cognitive behavioral therapy (CBT) has been suggested as a way to improve patients' psychological health and maintaining weight loss in the longer term. The added value of preoperative CBT to bariatric surgery was examined. Pre- and posttreatment and 1-year follow-up data are presented. Methods In a multi-center randomized controlled trial, CBT was compared to a treatment-as-usual (TAU) control group. Measurements were conducted pre- and posttreatment/pre-surgery (T0 and T1) and at 1-year post-surgery (T2). Patients in the intervention group received 10 individual, weekly sessions of preoperative CBT focused on modifying thoughts and behaviors regarding eating behavior, physical exercise, and postoperative life style. Outcome measures included weight change, eating behavior, eating disorders, depression, quality of life, and overall psychological health. Results Though no significant differences between conditions were found per time point, in the CBT, condition scores on external eating, emotional eating, depressive symptoms, and psychological distress decreased significantly more over time between pre- (T0) and posttreatment (T1) pre-surgery compared to TAU. No significant time x condition differences were found at 1-year post-surgery (T2). Conclusions Compared to TAU, preoperative CBT showed beneficial effects on eating behavior and psychological symptoms only from pretreatment to posttreatment/pre-surgery, but not from pre-surgery to 1-year post-surgery. Preoperative CBT does not seem to contribute to better long-term outcomes post-surgery. Recent studies suggest that the optimal time to initiate psychological treatment may be early in the postoperative period, before significant weight regain has occurred

Scaling in a Nonconservative Earthquake Model of Self-Organised Criticality

We numerically investigate the Olami-Feder-Christensen model for earthquakes in order to characterise its scaling behaviour. We show that ordinary finite size scaling in the model is violated due to global, system wide events. Nevertheless we find that subsystems of linear dimension small compared to the overall system size obey finite (subsystem) size scaling, with universal critical coefficients, for the earthquake events localised within the subsystem. We provide evidence, moreover, that large earthquakes responsible for breaking finite size scaling are initiated predominantly near the boundary.Comment: 6 pages, 6 figures, to be published in Phys. Rev. E; references sorted correctl

Response to “Letter in response to ‘Students’ age and parental level of education influence COVID-19 vaccination hesitancy’”

[No abstract available