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Biomedizinische Technik. Biomedical Engineering

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https://www.readbyqxmd.com/read/28525361/engineering-of-biodegradable-magnesium-alloy-scaffolds-to-stabilize-biological-myocardial-grafts
#1
Tobias Schilling, Michael Bauer, Christian Biskup, Axel Haverich, Thomas Hassel
OBJECTIVE: Regenerative bioprostheses are being investigated for replacement of dysfunctional myocardium worldwide. The aim of this study was to develop a degradable magnesium structure to mechanically support the delicate biological grafts during the early remodeling phase. METHODS: Sheets of magnesium alloys (LA33, LA63 and AX30) were manufactured into scaffolds by abrasive water jet cutting. Thereafter, their surface properties, corrosion kinetics, and breakage behaviors were investigated...
May 19, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28475487/can-somatosensory-electrical-stimulation-relieve-spasticity-in-post-stroke-patients-a-tms-pilot-study
#2
André Salles Cunha Peres, Victor Hugo Souza, João Marcos Yamasaki Catunda, Kelley Cristine Mazzeto-Betti, Taiza Elaine Grespan Santos-Pontelli, Claudia Domingues Vargas, Oswaldo Baffa, Draulio Barros de Araújo, Octávio Marques Pontes-Neto, João Pereira Leite, Marco Antonio Cavalcanti Garcia
Evidence suggests that somatosensory electrical stimulation (SES) may decrease the degree of spasticity from neural drives, although there is no agreement between corticospinal modulation and the level of spasticity. Thus, stroke patients and healthy subjects were submitted to SES (3 Hz) for 30' on the impaired and dominant forearms, respectively. Motor evoked potentials induced by single-pulse transcranial magnetic stimulation were collected from two forearm muscles before and after SES. The passive resistance of the wrist joint was measured with an isokinetic system...
May 5, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28475486/a-new-method-for-qrs-detection-in-ecg-signals-using-qrs-preserving-filtering-techniques
#3
Tanushree Sharma, Kamalesh K Sharma
Detection of QRS complexes in ECG signals is required for various purposes such as determination of heart rate, feature extraction and classification. The problem of automatic QRS detection in ECG signals is complicated by the presence of noise spectrally overlapping with the QRS frequency range. As a solution to this problem, we propose the use of least-squares-optimisation-based smoothing techniques that suppress the noise peaks in the ECG while preserving the QRS complexes. We also propose a novel nonlinear transformation technique that is applied after the smoothing operations, which equalises the QRS amplitudes without boosting the supressed noise peaks...
May 5, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28467307/heart-valves-from-polyester-fibers-a-preliminary-6-month-in-vivo-study
#4
Antoine Vaesken, Anne Pelle, Graciela Pavon-Djavid, Jeanne Rancic, Nabil Chakfe, Frederic Heim
Transcatheter aortic valve implantation (TAVI) has become a popular alternative technique to surgical valve replacement for critical patients. Biological valve tissue has been used in TAVI procedures for over a decade, with over 150,000 implantations to date. However, with only 6 years of follow up, little is known about the long-term durability of biological tissue. Moreover, the high cost of tissue harvesting and chemical treatment procedures favor the development of alternative synthetic valve leaflet materials...
May 3, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28467306/in-service-characterization-of-a-polymer-wick-based-quasi-dry-electrode-for-rapid-pasteless-electroencephalography
#5
Paulo Pedrosa, Patrique Fiedler, Vanessa Pestana, Beatriz Vasconcelos, Hugo Gaspar, Maria H Amaral, Diamantino Freitas, Jens Haueisen, João M Nóbrega, Carlos Fonseca
A novel quasi-dry electrode prototype, based on a polymer wick structure filled with a specially designed hydrating solution is proposed for electroencephalography (EEG) applications. The new electrode does not require the use of a conventional electrolyte paste to achieve a wet, low-impedance scalp contact. When compared to standard commercial Ag/AgCl sensors, the proposed wick electrodes exhibit similar electrochemical noise and potential drift values. Lower impedances are observed when tested in human volunteers due to more effective electrode/skin contact...
May 3, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28467305/breast-sentinel-lymph-node-biopsy-with-imaging-towards-minimally-invasive-surgery
#6
REVIEW
Fredrick Johnson Joseph, Alexander van Oepen, Michael Friebe
Breast sentinel lymph nodes are still commonly assessed through complete lymph node dissections, which is a time-consuming and radical approach because the nodes are difficult to identify. To prevent false diagnosis and achieve accurate results, minimally invasive, image-guided procedures are applied and constantly improved. The purpose of this paper is to present the currently used imaging modalities ultrasound, fluorescence, single-photon emission computed tomography (SPECT), magnetic resonance imaging (MRI) and hybrid imaging methods and comparing their effectiveness for breast sentinel lymph node biopsy...
May 3, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28453437/umbilical-cord-as-human-cell-source-for-mitral-valve-tissue-engineering-venous-vs-arterial-cells
#7
Axel Malischewski, Ricardo Moreira, Luis Hurtado, Valentine Gesché, Thomas Schmitz-Rode, Stefan Jockenhoevel, Petra Mela
Around 2% of the population in developed nations are affected by mitral valve disease and available valvular replacements are not designed for the atrioventricular position. Recently our group developed the first tissue-engineered heart valve (TEHV) specifically designed for the mitral position - the TexMi valve. The valve recapitulates the main components of the native valve, i.e. annulus, asymmetric leaflets and the crucial chordae tendineae. In the present study, we evaluated the human umbilical cord as a clinically applicable cell source for the TexMi valve...
April 28, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28448270/a-new-in-vitro-spine-test-rig-to-track-multiple-vertebral-motions-under-physiological-conditions
#8
Agnes Beckmann, Christian Herren, Marion Mundt, Jan Siewe, Philipp Kobbe, Rolf Sobottke, Hans-Christoph Pape, Marcus Stoffel, Bernd Markert
In vitro pure moment spine tests are commonly used to analyse surgical implants in cadaveric models. Most of the tests are performed at room temperature. However, some new dynamic instrumentation devices and soft tissues show temperature-dependent material properties. Therefore, the aim of this study is to develop a new test rig, which allows applying pure moments on lumbar spine specimens in a vapour-filled chamber at body temperature. As no direct sight is given in the vapour-filled closed chamber, a magnetic tracking (MT) system with implantable receivers was used...
April 27, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28384099/a-decomposition-model-and-voxel-selection-framework-for-fmri-analysis-to-predict-neural-response-of-visual-stimuli
#9
Savita V Raut, Dinkar M Yadav
This paper presents an fMRI signal analysis methodology using geometric mean curve decomposition (GMCD) and mutual information-based voxel selection framework. Previously, the fMRI signal analysis has been conducted using empirical mean curve decomposition (EMCD) model and voxel selection on raw fMRI signal. The erstwhile methodology loses frequency component, while the latter methodology suffers from signal redundancy. Both challenges are addressed by our methodology in which the frequency component is considered by decomposing the raw fMRI signal using geometric mean rather than arithmetic mean and the voxels are selected from EMCD signal using GMCD components, rather than raw fMRI signal...
April 6, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28358711/the-influence-of-implant-body-and-thread-design-of-mini-dental-implants-on-the-loading-of-surrounding-bone-a-finite-element-analysis
#10
Arpad Toth, Istabrak Hasan, Christoph Bourauel, Torsten Mundt, Reiner Biffar, Friedhelm Heinemann
Mini dental implants (MDI) were once thought of as transitional implants for treatment in selected clinical situations. Their reduced diameter makes them a very attractive option for patients with poor tolerance to maxillary and mandibular prostheses. Using the method of finite element analysis, a series of different designed MDI prototypes have been investigated. The prototypes differed in the geometry of implant body and/or design of implant head. The load transfer of the implant prototypes to the idealised alveolar bone has been regarded and the prototypes have been compared to each other and to a number of standard commercial implants...
March 30, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28306517/biomechanical-analysis-of-stiffness-and-fracture-displacement-after-using-pmma-augmented-sacroiliac-screw-fixation-for-sacrum-fractures
#11
Andreas Höch, Richard Schimpf, Niels Hammer, Stefan Schleifenbaum, Michael Werner, Christoph Josten, Jörg Böhme
Cement augmentation of pedicle screws is the gold standard for the stabilization of osteoporotic fractures of the spine. In-screw cement augmentation, in which cement is injected through the cannula, is another option for fracture stabilization of fragility fractures of the sacrum. However, biomechanical superiority of this technique compared to conventional sacroiliac screw fixation has not been tested. The present study compares the stability of cement-augmented and non-cement-augmented sacroiliac screw fixation in osteoporotic sacrum fractures under cyclic loading...
March 15, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28306516/identification-and-classification-of-upper-limb-motions-using-pca
#12
Karan Veer, Renu Vig
This paper describes the utility of principal component analysis (PCA) in classifying upper limb signals. PCA is a powerful tool for analyzing data of high dimension. Here, two different input strategies were explored. The first method uses upper arm dual-position-based myoelectric signal acquisition and the other solely uses PCA for classifying surface electromyogram (SEMG) signals. SEMG data from the biceps and the triceps brachii muscles and four independent muscle activities of the upper arm were measured in seven subjects (total dataset=56)...
March 15, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28258973/rapid-automated-mosaicking-of-the-human-corneal-subbasal-nerve-plexus
#13
Yash J Vaishnav, Stuart A Rucker, Keshav Saharia, Nancy A McNamara
Corneal confocal microscopy (CCM) is an in vivo technique used to study corneal nerve morphology. The largest proportion of nerves innervating the cornea lie within the subbasal nerve plexus, where their morphology is altered by refractive surgery, diabetes and dry eye. The main limitations to clinical use of CCM as a diagnostic tool are the small field of view of CCM images and the lengthy time needed to quantify nerves in collected images. Here, we present a novel, rapid, fully automated technique to mosaic individual CCM images into wide-field maps of corneal nerves...
March 4, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28258972/design-of-a-mechanism-for-converting-the-energy-of-knee-motions-by-using-electroactive-polymers
#14
Pascal Armbruster, Yannick Oster, Marcel Vogt, Christian Pylatiuk
Harvesting energy from human body motions has become a promising option to prolong battery life for powering medical devices for autonomy. Up to now, different generating principles including dielectric electroactive polymers (DEAPs) have been suggested for energy conversion. However, there is a lack of mechanisms that are specifically designed to convert energy with DEAPs. In a proof of concept study, a mechanical system was designed for stretching DEAPs in those phases of the gait cycle, in which the muscles mainly perform negative work...
March 4, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28258971/an-image-processing-strategy-to-extract-important-information-suitable-for-a-low-size-stimulus-pattern-in-a-retinal-prosthesis
#15
Yili Chen, Jixiang Fu, Dawei Chu, Rongmao Li, Yaoqin Xie
BACKGROUND: A retinal prosthesis is designed to help the blind to obtain some sight. It consists of an external part and an internal part. The external part is made up of a camera, an image processor and an RF transmitter. The internal part is made up of an RF receiver, implant chip and microelectrode. METHODS: Currently, the number of microelectrodes is in the hundreds, and we do not know the mechanism for using an electrode to stimulate the optic nerve. A simple hypothesis is that the pixels in an image correspond to the electrode...
March 4, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28157688/pattern-recognition-of-enrichment-levels-of-selex-based-candidate-aptamers-for-human-c-reactive-protein
#16
Xinliang Yu, Ruqin Yu, Xiaohai Yang
Selecting aptamers for human C-reactive protein (CRP) would be of critical importance in predicting the risk for cardiovascular disease. The enrichment level of DNA aptamers is an important parameter for selecting candidate aptamers for further affinity and specificity determination. This paper is the first report on pattern recognition used for CRP aptamer enrichment levels in the systematic evolution of ligands by exponential enrichment (SELEX) process, by applying structure-activity relationship models. After generating 10 rounds of graphene oxide (GO)-SELEX and 1670 molecular descriptors, eight molecular descriptors were selected and five latent variables were then obtained with principal component analysis (PCA), to develop a support vector classification (SVC) model...
May 24, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/27574854/computer-assisted-evaluation-of-plate-osteosynthesis-of-diaphyseal-femur-fracture-considering-interfragmentary-movement-a-finite-element-study
#17
Claudia Wittkowske, Stefan Raith, Maximilian Eder, Alexander Volf, Jan S Kirschke, Benjamin König, Christoph Ihle, Hans-Günther Machens, Stefan Döbele, Laszlo Kovacs
A semi-automated workflow for evaluation of diaphyseal fracture treatment of the femur has been developed and implemented. The aim was to investigate the influence of locking compression plating with diverse fracture-specific screw configurations on interfragmentary movements (IFMs) with the use of finite element (FE) analysis. Computed tomography (CT) data of a 22-year-old non-osteoporotic female were used for patient specific modeling of the inhomogeneous material properties of bone. Hounsfield units (HU) were exported and assigned to elements of a FE mesh and converted to mechanical properties such as the Young's modulus followed by a linear FE analysis performed in a semi-automated fashion...
May 24, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/27567597/accuracy-of-leg-alignment-measurements-from-antero-posterior-radiographs
#18
Rahul Khare, Branislav Jaramaz
After a knee replacement procedure, postoperative radiological assessment is carried out to evaluate outcome and predict procedure success. For this assessment, long-standing load-bearing antero-posterior radiographs are used to carry out manual identification of anatomic landmarks. These landmarks are subsequently used to estimate leg alignment. The positions of the landmarks in the radiographs are affected by the patient pose and the X-ray projection center. Although there is some past work exploring the impact of patient pose on the landmarks in the radiographs, there is no previous work on the impact of the X-ray projection center on the estimated leg alignment...
May 24, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/27514073/holoentropy-enabled-decision-tree-for-automatic-classification-of-diabetic-retinopathy-using-retinal-fundus-images
#19
Vijay Mahadeo Mane, D V Jadhav
Diabetic retinopathy (DR) is the most common diabetic eye disease. Doctors are using various test methods to detect DR. But, the availability of test methods and requirements of domain experts pose a new challenge in the automatic detection of DR. In order to fulfill this objective, a variety of algorithms has been developed in the literature. In this paper, we propose a system consisting of a novel sparking process and a holoentropy-based decision tree for automatic classification of DR images to further improve the effectiveness...
May 24, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/27505082/shear-stress-and-von-mises-stress-distributions-in-the-periphery-of-an-embedded-acetabular-cup-implant-during-impingement
#20
Christoph Arndt, Alexandra Görgner, Carsten Klöhn, Roger Scholz, Christian Voigt
As literature implies, daily activities of total hip arthroplasty (THA) patients may include movements prone to implant-implant impingement. Thus, high shear stresses may be induced at the acetabular implant-bone interface, increasing the risk of implant loosening. The aim of the current study is to determine whether or not impingement events may pose an actual risk to acetabular periprosthetic bone. An existing experimental workflow was augmented to cover complete three-dimensional strain gage measurement...
May 24, 2017: Biomedizinische Technik. Biomedical Engineering
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