Search results for "Biomedical engineering"

Color-Doppler Flow Mapping of the Heart in Normal Subjects

1988

Assessment of a mattress with phase change materials using a thermal and perception test

2017

Abstract Mattresses composed by phase change materials (PCMs) may improve the thermoregulation of the human body. The aim of the study was to analyse the thermoregulatory efficiency of a PCMs and a conventional mattresses via the evaluation of the skin temperature, thermal comfort and thermal perception. Twenty participants lay on a PCMs and a conventional mattress for 20 min in each mattress on the same day. Skin temperature of the back of the participants and temperature of the sheet of the mattresses were measured before and immediately after lying on each mattress. Thermal comfort and thermal perception were also reported during the last minute of the lying test. The PCMs mattress resul…

Electronic Design for a Bleeding Detector to be Used in Intraoperative Radiotherapy Applications

2021

An electronic design for a bleeding detector used with mobile linac during intraoperative radiotherapy (IORT) is presented. It consists on a readout circuit based on a De Sauty Bridge and a wireless power supply using a supercapacitor. The goal is the measurement of the height of fluid present in the applicator in order to avoid a misadministration dose during the irradiation process. A minimum measurement height of 5 mm is required by clinic to be confident with the selected radiation dose. The measurement circuit uses a capacitive sensor which detects variations lower than 0.1 pF. The readout circuit converts dynamic capacitance variation from the bleeding detector into an analog voltage …

2014

This study was performed to explore the feasibility of tracing nanoparticles for drug transport in the healthy rat brain with a clinical MRI scanner. Phantom studies were performed to assess the R1 ( =  1/T1) relaxivity of different magnetically labeled nanoparticle (MLNP) formulations that were based on biodegradable human serum albumin and that were labeled with magnetite of different size. In vivo MRI measurements in 26 rats were done at 3T to study the effect and dynamics of MLNP uptake in the rat brain and body. In the brain, MLNPs induced T1 changes were quantitatively assessed by T1 relaxation time mapping in vivo and compared to post-mortem results from fluorescence imaging. Followi…

Multicomponent polymeric micelles based on polyaspartamide as tunable fluorescent pH-window biosensors

2010

Abstract PHEA-PEG 5000 -C 16 is a polyaspartamide polymer with appended hydrophilic PEG 5000 functions and hydrophobic n-C 16 units forming biocompatible micelles with a CAC as low as 1.8 × 10 −7  M. The protonation and acidity constants of the polymer's amino and carboxylic groups have been determined by potentiometric titrations at five different concentrations higher than CAC, finding concentration-independent values. Viscosity and polarity of the micellar core have been investigated by means of fluorescent probes, finding local values comparable to those of pure toluene and to the core of sodium dodecyl sulphate micelles, independently on the protonation degree of the polymer. The fluor…

Water-Soluble Aza-BODIPYs: Biocompatible Organic Dyes for High Contrast In Vivo NIR-II Imaging

2020

International audience; A simple NIR-II emitting water-soluble system has been developed and applied in vitro and in vivo. In vitro, the fluorophore quickly accumulated in 2D and 3D cell cultures and rapidly reached the tumor in rodents, showing high NIR-II contrast for up to 1 week. This very efficient probe possesses all the qualities necessary for translation to the clinic as well as for the development of NIR-II emitting materials.

Experimental Evaluation of a New Electromagnetic Shock Wave Source

1987

Clinical application of new shock wave sources always warrants prior experimental evaluation of the stone disintegration capabilities and characterization of the shock wave impulses. The least possible tissue traumatization is necessary for successful clinical introduction. After the spark-gap generation of shock waves with semi-ellipsoid focussing had been introduced to the urological armamentarium for extracorporeal destruction of renal and ureteral stones in 1980 (Chaussy 1982), new modes of shock wave generation have been developed. In cooperation with the Siemens Company of Erlangen, Germany, a new electromagnetic shock wave source was evaluated by in vitro and in vivo animal experimen…

Multinucleated giant cells in the implant bed of bone substitutes are foreign body giant cells-New insights into the material-mediated healing process

2017

In addition to macrophages, multinucleated giant cells (MNGCs) are involved in the tissue reaction to a variety of biomaterials. Especially in the case of bone substitute materials it has been assumed that the MNGCs are osteoclasts, based on the chemical and physical similarity of many materials to the calcified matrix and the bony environment in which they are used. However, many studies indicate that these cells belong to the cell line of the foreign body giant cells (FBGCs), which are of "inflammatory origin", although they have been shown to possess both a pro- and also anti-inflammatory phenotype. Moreover, no information is available about their role in the tissue reaction to bone sub…

Small-sized granules of biphasic bone substitutes support fast implant bed vascularization

2015

The present study investigated the influence of granule size of 2 biphasic bone substitutes (BoneCeramic® 400-700 μm and 500-1000 μm) on the induction of multinucleated giant cells (MNGCs) and implant bed vascularization in a subcutaneous implantation model in rats. Furthermore, degradation mechanisms and particle phagocytosis of both materials were examined by transmission electron microscopy (TEM). Both granule types induced tissue reactions involving primarily mononuclear cells and only small numbers of MNGCs. Higher numbers of MNGCs were detected in the group with small granules starting on day 30, while higher vascularization was observed only at day 10 in this group. TEM analysis reve…

A Novel Approach to Propagation Pattern Analysis in Intracardiac Atrial Fibrillation Signals

2010

The purpose of this study is to investigate propagation patterns in intracardiac signals recorded during atrial fibrillation (AF) using an approach based on partial directed coherence (PDC), which evaluates directional coupling between multiple signals in the frequency domain. The PDC is evaluated at the dominant frequency of AF signals and tested for significance using a surrogate data procedure specifically designed to assess causality. For significantly coupled sites, the approach allows also to estimate the delay in propagation. The methods potential is illustrated with two simulation scenarios based on a detailed ionic model of the human atrial myocyte as well as with real data recordi…