Rectification of the EMG is an unnecessary and inappropriate step in the calculation of Corticomuscular coherence

Corticomuscular coherence (CMC) estimation is a frequency domain method used to detect a linear coupling between rhythmic activity recorded from sensorimotor cortex (EEG or MEG) and the electromyogram (EMG) of active muscles. In motor neuroscience, rectification of the surface EMG is a common pre-processing step prior to calculating CMC, intended to maximize information about action potential timing, whilst suppressing information relating to motor unit action potential (MUAP) shape. Rectification is believed to produce a general shift in the EMG spectrum towards lower frequencies, including those around the mean motor unit discharge rate. However, there are no published data to support the claim that EMG rectification enhances the detection of CMC. Furthermore, performing coherence analysis after the non-linear procedure of rectification, which results in a significant distortion of the EMG spectrum, is considered fundamentally flawed in engineering and digital signal processing. We calculated CMC between sensorimotor cortex EEG and EMG of two hand muscles during a key grip task in 14 healthy subjects. CMC calculated using unrectified and rectified EMG was compared. The use of rectified EMG did not enhance the detection of CMC, nor was there any evidence that MUAP shape information had an adverse effect on the CMC estimation. EMG rectification had inconsistent effects on the power and coherence spectra and obscured the detection of CMC in some cases. We also provide a comprehensive theoretical analysis, which, along with our empirical data, demonstrates that rectification is neither necessary nor appropriate in the calculation of CMC.     

Osteo-articular diseases as comorbidity in non-orthopaedic surgery

Osteo-articular diseases have significant presence among general population. Osteo-articular disorders can be caused by disease or by trauma. There are many osteo-articular diseases which have influence on general state of the organysm and on other present diseases in a various level. The influence appears by increasing risk of main disease complications, limited movement complicates postoperative treatment of main disease and medicament therapy of osteo-articular disease sometimes modifies perioperative therapy of main disease. Trauma as comorbidity needs urgent care and, in the same time, it is a huge complication for the injured condition. Osteoarticular trauma healing usually lasts several weeks, so it prolongs the healing of intercurrent surgical disease. Osteo-articular changes as comorbidity during the acute surgical disease healing need proper preoperative preparing, With the aim to minimise perioperative morbidity and mortality.     

Evaluation of 3D blood flow patterns and wall shear stress in the normal and dilated thoracic aorta using flow-sensitive 4D CMR

Background

The purpose of this study was to investigate 3D flow patterns and vessel wall parameters in patients with dilated ascending aorta, age-matched subjects, and healthy volunteers.

Methods

Thoracic time-resolved 3D phase contrast CMR with 3-directional velocity encoding was applied to 33 patients with dilated ascending aorta (diameter ≥40 mm, age=60±16 years), 15 age-matched normal controls (diameter ≤37 mm, age=68±7.5 years) and 15 young healthy volunteers (diameter ≤30 mm, age=23±2 years). 3D blood flow was visualized and flow patterns were graded regarding presence of supra-physiologic-helix and vortex flow using a semi-quantitative 3-point grading scale. Blood flow velocities, regional wall shear stress (WSS), and oscillatory shear index (OSI) were quantified.

Results

Incidence and strength of supra-physiologic-helix and vortex flow in the ascending aorta (AAo) was significantly higher in patients with dilated AAo (16/33 and 31/33, grade 0.9±1.0 and 1.5±0.6) than in controls (2/15 and 7/15, grade 0.2 ± 0.6 and 0.6 ± 0.7, P<.05) or healthy volunteers (1/15 and 0/15, grade 0.1 ± 0.3 P<.05). Greater strength of the ascending aortic helix and vortex flow were associated with significant differences in AAo diameters (P<.05). Peak systolic WSS in the ascending aorta and aortic arch was significantly lower in patients with dilated AAo (P<.0157-.0488). AAo diameter positively correlated to time to peak systolic velocities (r=0.30-0.53, P<.04), OSI (r=0.33-0.49, P<0.02) and inversely correlated to peak systolic WSS (r=0.32-0.40, P<.03). Peak systolic WSS was significantly lower in AAo aneurysms at the right and outer curvature within the AAo and proximal arch (P<.01-.05).

Conclusions

Increase in AAo diameter is significantly correlated with the presence and strength of supra-physiologic-helix and vortex formation in the AAo, as well with decrease in systolic WSS and increase in OSI.     

Antitumor activity from antigen-specific CD8 T cells generated in vivo from genetically engineered human hematopoietic stem cells

The goal of cancer immunotherapy is the generation of an effective, stable, and self-renewing antitumor T-cell population. One such approach involves the use of high-affinity cancer-specific T-cell receptors in gene-therapy protocols. Here, we present the generation of functional tumor-specific human T cells in vivo from genetically modified human hematopoietic stem cells (hHSC) using a human/mouse chimera model. Transduced hHSC expressing an HLA-A*0201–restricted melanoma-specific T-cell receptor were introduced into humanized mice, resulting in the generation of a sizeable melanoma-specific naïve CD8⁺ T-cell population. Following tumor challenge, these transgenic CD8⁺ T cells, in the absence of additional manipulation, limited and cleared human melanoma tumors in vivo. Furthermore, the genetically enhanced T cells underwent proper thymic selection, because we did not observe any responses against non–HLA-matched tumors, and no killing of any kind occurred in the absence of a human thymus. Finally, the transduced hHSC established long-term bone marrow engraftment. These studies present a potential therapeutic approach and an important tool to understand better and to optimize the human immune response to melanoma and, potentially, to other types of cancer.     

In Vivo Imaging and Computational Analysis of the Aortic Root. Application in Clinical Research and Design of Transcatheter Aortic Valve Systems

Valvular heart disease is a major cause of morbidity and mortality in developing and industrialized countries. For patients with advanced symptomatic disease, surgical open-heart valve replacement is an effective treatment, supported by long-term outcome data. More recently, less-invasive transcatheter approaches for valve replacement/implantation have been developed for patients that are not considered surgical candidates. An understanding of valvular and paravalvular anatomy and biomechanics is pivotal for the optimization of interventional valve procedures. Advanced imaging is increasingly used not only for clinical guidance but also for the design and further improvement of transcatheter valve systems. Computed tomography is particularly attractive because it acquires high-resolution volumetric data sets of the root including the leaflets and coronary artery ostia, with sufficient temporal resolution for multi-phasic analysis. These volumetric data sets allow subsequent 3-D and 4-D display, reconstruction in unlimited planes, and mathematical modeling. Computer modeling, specifically finite element analysis, of devices intended for implantation in the aortic root, allows for structural analysis of devices and modeling of the interaction between the device and cardiovascular anatomy. This paper will provide an overview of computer modeling of the aortic root and describe FEA approaches that could be applied to TAVI and have an impact on clinical practice and device design.