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Time filter

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Cord, Switzerland

Berndt K.,Balgrist University Hospital
Journal of the American Association for Laboratory Animal Science : JAALAS | Year: 2012

Intraarterial chemotherapy (IAC) is considered effective for the treatment of solid tumors with high local doses of systemically toxic chemotherapeutics. Osteosarcoma, which is often located in the extremities, is a potential target for IAC. However, the efficacy of this treatment modality has varied, and standardized protocols are difficult to establish due to tumor heterogeneity and the limited numbers of patients available for clinical trials. Reproducible experimental models are needed to further investigate IAC in osteosarcoma. Here, we describe a new microsurgical technique for repeated infusion of drugs into the mouse femoral artery for local treatment of experimental intratibial metastasizing osteosarcoma. We successfully achieved 5 catheterizations at 3-d intervals in 70% of the mice tested. Laser speckle imaging indicated a maximal 50% reduction in blood flow around the ankle region of catheterized legs infused with 0.5 mg/kg cisplatin. However, blood flow in the front feet was affected only minimally. Histologic examination of catheterized arteries of saline control or cisplatin-treated mice showed circular fibrinoid media necrosis and partial thrombosis, but total occlusion of the arteries was not observed. The method we describe for repeated transient catheterization of the mouse femoral artery likely will be useful in future studies comparing the efficacies of intraarterial and systemic cisplatin treatment of intratibial metastasizing osteosarcoma in mice under standardized conditions. Source


Sarabadani Tafreshi A.,ETH Zurich | Sarabadani Tafreshi A.,University of Zurich | Klamroth-Marganska V.,Balgrist University Hospital | Nussbaumer S.,Hocoma | Riener R.,Balgrist University Hospital
IEEE Transactions on Biomedical Engineering | Year: 2015

Prolonged bed rest has significant negative impacts on the human body, particularly on the cardiovascular system. To overcome adverse effects and enhance functional recovery in bedridden patients, the goal is to mobilize patients as early as possible while controlling and stabilizing their cardiovascular system. In this paper, we used a robotic tilt table that allows early mobilization by modulating body inclination and automated leg movement to control the cardiovascular variables heart rate (HR) or systolic or diastolic blood pressures (sBP, dBP). The design and use of a control system is often done with a simulation model of a plant, but the time-variant and nonlinear nature of the cardiovascular system and subject-specific responses to external stimuli makes the modeling and identification challenging. Instead, we implemented an intelligent self-learning fuzzy controller that does not need any prior knowledge about the plant. The controller modulates the body inclination in order to adjust the cardiovascular parameters, with leg movement considered as a perturbing factor to the controller. The controller performance was evaluated in six healthy subjects. Measured mean values of HR, sBP, and dBP differed from desired reference values by 1.11 beats/min, 5.10 mmHg, and 2.69 mmHg, respectively. With this new control strategy, HR and dBP could be successfully controlled within medically tolerable ranges (deviations < 2.5 beats/min and < 5 mmHg from desired values, respectively). The control of sBP was less accurate; the results suggest that simultaneous control of multiple input stimuli rather than only adaptive automatic change of the tilt table angle might improve the controllability. © 1964-2012 IEEE. Source


Bontrager D.,ETH Zurich | Novak D.,ETH Zurich | Novak D.,Balgrist University Hospital | Zimmermann R.,University of Zurich | And 5 more authors.
Conference Proceedings - IEEE International Conference on Systems, Man and Cybernetics | Year: 2014

Functional near-infrared spectroscopy (fNIRS) is a noninvasive optical method that measures cortical activity based on hemodynamics in the brain. Physiological signals (biosignals), such as blood pressure and respiration, are known to appear in cortical fNIRS recordings. Some biosignal components occupy the same frequency band as the cortical response, and respond to the subjects activity. To process an fNIRS signal in a braincomputer interface, it is desirable to know which components of the signal come from cortical response, and which come from biosignal interference. Numerous filtering methods have been proposed to this end with mixed success, possibly because they assume that the cortical and physiological signals combine linearly, or that biosignals do not correlate with subject behavior. Here, we propose an adaptive filter with a cost function based on mutual information to selectively remove information that correlates with blood pressure from the fNIRS signal. The filter was tested with real and simulated data. The real signals were measured on seven healthy subjects performing an isometric pinching task. Cross-correlation and mutual information were employed as performance measures. The filter successfully removed correlations between blood pressure and the fNIRS signal, by an equal or greater amount compared to a traditional recursive least squares adaptive filter. Blood pressure was found to be the most informative signal to classify rest and active periods using linear discriminant analysis. Any task information in the fNIRS signal was redundant to that expressed by blood pressure. © 2014 IEEE. Source


Jaremko J.L.,University of Alberta | Lambert R.G.W.,University of Alberta | Zubler V.,Balgrist University Hospital | Weber U.,Balgrist University Hospital | And 8 more authors.
Journal of Rheumatology | Year: 2014

Objective. As a wider variety of therapeutic options for osteoarthritis (OA) becomes available, there is an increasing need to objectively evaluate disease severity on magnetic resonance imaging (MRI). This is more technically challenging at the hip than at the knee, and as a result, few systematic scoring systems exist. The OMERACT (Outcome Measures in Rheumatology) filter of truth, discrimination, and feasibility can be used to validate image-based scoring systems. Our objective was (1) to review the imaging features relevant to the assessment of severity and progression of hip OA; and (2) to review currently used methods to grade these features in existing hip OA scoring systems. Methods. A systematic literature review was conducted. MEDLINE keyword search was performed for features of arthropathy (such as hip + bone marrow edema or lesion, synovitis, cyst, effusion, cartilage, etc.) and scoring system (hip + OA + MRI + score or grade), with a secondary manual search for additional references in the retrieved publications. Results. Findings relevant to the severity of hip OA include imaging markers associated with inflammation (bone marrow lesion, synovitis, effusion), structural damage (cartilage loss, osteophytes, subchondral cysts, labral tears), and predisposing geometric factors (hip dysplasia, femoral-acetabular impingement). Two approaches to the semiquantitative assessment of hip OA are represented by Hip OA MRI Scoring System (HOAMS), a comprehensive whole organ assessment of nearly all findings, and the Hip Inflammation MRI Scoring System (HIMRISS), which selectively scores only active lesions (bone marrow lesion, synovitis/effusion). Validation is presently confined to limited assessment of reliability. Conclusion. Two methods for semiquantitative assessment of hip OA on MRI have been described and validation according to the OMERACT Filter is limited to evaluation of reliability. (First Release Nov 15 2013; J Rheumatol 2014;41:359-69; doi:10.3899/jrheum.131082). © The Journal of Rheumatology Copyright 2014. All rights reserved. Source


Maksymowych W.P.,University of Alberta | Cibere J.,Arthritis Research Centre of Canada | Loeuille D.,Nancy University Hospital Center | Weber U.,Balgrist University Hospital | And 6 more authors.
Journal of Rheumatology | Year: 2014

Objective. Development of a validated magnetic resonance image (MRI) scoring system is essential in hip OA because radiographs are insensitive to change. We assessed the feasibility and reliability of 2 previously developed scoring methods: (1) the Hip Inflammation MRI Scoring System (HIMRISS) and (2) the Hip Osteoarthritis MRI Scoring System (HOAMS). Methods. Six readers (3 radiologists, 3 rheumatologists) participated in 2 reading exercises. In Reading Exercise 1, MRI of the hip of 20 subjects were read at a single time point followed by further standardization of methodology. In Reading Exercise 2, MRI of the hip of 18 subjects from a randomized controlled trial, assessed at 2 timepoints, and 27 subjects from a cross-sectional study were read for HIMRISS and HOAMS bone marrow lesions (BML) and synovitis. Reliability was assessed using intraclass correlation coefficient (ICC) and kappa statistics. Results. Both methods were considered feasible. For Reading 1, HIMRISS ICC were 0.52, 0.61, 0.70, and 0.58 for femoral BML, acetabular BML, effusion, and total scores, respectively; and for HOAMS, summed BML and synovitis ICC were 0.52 and 0.46, respectively. For Reading 2, HIMRISS and HOAMS ICC for BML and synovitis-effusion improved substantially. Interobserver reliability for change scores was 0.81 and 0.71 for HIMRISS femoral and HOAMS summed BML, respectively. Responsiveness and discrimination was moderate to high for synovitis-effusion. Significant associations were noted between BML or synovitis scores and Western Ontario and McMaster Universities Osteoarthritis Index pain scores for baseline values (p < 0.001). Conclusion. The BML and synovitis-effusion components of both HIMRISS and HOAMS scoring systems are feasible and reliable, and should be validated further. (First Release Nov 15 2013; J Rheumatol 2014;41:370.8; doi:10.3899/jrheum.131083). © The Journal of Rheumatology Copyright 2014. All rights reserved. Source

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