Search results for "Biomedical engineering"
showing 10 items of 2020 documents
Experimente zur Entwicklung eines implantierbaren und dauernd funktionsfähigen Glukose-Sensors auf Basis der Polarimetrie - Experiments Aimed at Enab…
1995
In vitro and in vivo experiments devised with the aim of developing a permanently implantable glucose sensor based on polarimetry are described. It was found that in ultrafiltrated human blood plasma the overall optical rotation was 94% specific for glucose, and that polarisation photometry yielded a sufficiently sensitive signal for in vivo glucose detection. The three types of capillary membrane intended for implantation that we tested, revealed an in vitro response time to glucose concentration of 10 minutes; when implanted, they maintain this over a period of weeks, during which time the same glucose concentrations can be measured daily in ultrafiltrated capillary fluid as in the blood …
Nuclear Magnetic Resonance for Cultural Heritage
2007
Abstract Nuclear magnetic resonance (NMR) portable devices are now being used for nondestructive in situ analysis of water content, pore space structure and protective treatment performance in porous media in the field of cultural heritage. It is a standard procedure to invert T 1 and T 2 relaxation data of fully water-saturated samples to get “pore size” distributions, but the use of T 2 requires great caution. It is well known that dephasing effects due to water molecule diffusion in a magnetic field gradient can affect transverse relaxation data, even if the smallest experimentally available half echo time τ is used in Carr–Purcell–Meiboom–Gill experiments. When a portable single-sided N…
Evaluation of Risk Parameters in Bone Regeneration Using a Customized Titanium Mesh
2019
PURPOSE The aim of the study was an evaluation of risk factors for an innovative bone regeneration technique using a customized titanium mesh that was tested in a clinical setting. MATERIALS AND METHODS This retrospective study included 65 patients with 70 grafting procedures of osseous defects of the jaws with a customized titanium mesh together with Advanced- and Injectable-Platelet-Rich Fibrin (A- and I-PRF), resorbable membranes, and bone grafting materials. Exposures of the meshes and grafting outcome were analyzed according to a novel classification as (a) punctual and (b) tooth width or complete exposure of the mesh (c). No exposure was stated as (d). RESULTS In 37% of cases, exposur…
Triple-target stimuli-responsive anti-COVID-19 face mask with physiological virus-inactivating agents
2021
Conventional face masks to prevent SARS-CoV-2 transmission are mostly based on a passive filtration principle. Ideally, anti-COVID-19 masks should protect the carrier not only by size exclusion of virus aerosol particles, but also be able to capture and destroy or inactivate the virus. Here we present the proof-of-concept of a filter mat for such a mask, which actively attracts aerosol droplets and kills the virus. The electrospun mats are made of polycaprolactone (PCL) a hydrophilic, functionalizable and biodegradable polyester, into which inorganic polyphosphate (polyP) a physiological biocompatible, biodegradable and antivirally active polymer (chain length, ∼40 Pi units) has been integr…
Bioadhesive monolayer film for the in vitro transdermal delivery of sumatriptan
2006
The work presented here aims to develop a bioadhesive monolayer film containing sumatriptan as adjuvant for the treatment of headache pain in a severe migraine attack. Permeation experiments were performed from the films prepared and from the respective solution, to evaluate the relevant permeation parameters. The effect of the penetration enhancers Transcutol, 2-pyrrolidone, and polyethylene glycol 600 was evaluated. The results obtained show that Transcutol and 2-pyrrolidone decreased sumatriptan permeation from solution, whereas a modest increase was produced by polyethylene glycol 600. The enhancers produced the same effects when they were included in the film. Compared to solution, the…
Combination strategies for enhancing transdermal absorption of sumatriptan through skin
2006
The aim of the present work was to characterize in vitro sumatriptan transdermal absorption through human skin and to investigate the effect of chemical enhancers and iontophoresis applied both individually and in combination. A secondary objective was to compare the results obtained with those in porcine skin under the same conditions, in order to characterize the relationship between the two skin models and validate the porcine model for further research use. Transdermal flux of sumatriptan was determined in different situations: (a) after pre-treatment of human skin with ethanol, Azone (1-dodecyl-azacycloheptan-2-one), polyethylene glycol 600 and R-(+)-limonene, (b) under iontophoresis a…
Biological tolerance of different materials in bulk and nanoparticulate form in a rat model: sarcoma development by nanoparticles
2006
In order to study the pathobiological impact of the nanometre-scale of materials, we evaluated the effects of five different materials as nanoparticulate biomaterials in comparison with bulk samples in contact with living tissues. Five groups out of 10 rats were implanted bilaterally for up to 12 months with materials of the same type, namely TiO 2 , SiO 2 , Ni, Co and polyvinyl chloride (PVC), subcutaneously with bulk material on one side of the vertebral column and intramuscularly with nanoparticulate material on the contralateral side. At the end of each implantation time, the site was macroscopically examined, followed by histological processing according to standard techniques. Malign…
Overcoming the barrier of CD8+ T cells: Two types of nano-sized carriers for siRNA transport
2019
Abstract Bioengineering immune cells via gene therapy offers treatment opportunities for currently fatal viral infections. Also cell therapeutics offer most recently a breakthrough technology to combat cancer. These primary human cells, however, are sensitive to toxic influences, which make the utilization of optimized physical transfection techniques necessary. The otherwise commonly applied delivery agents such as LipofectamineⓇ or strongly cationic polymer structures are not only unsuitable for in vivo experiments, but are also highly toxic to immune cells. This study aimed to improve the design of polymeric carrier systems for small interfering RNA, which would allow efficient internali…
Joined effects of pennation angle and tendon compliance on fibre length in isometric contractions: a simulation study.
1998
The main purpose of this study was to investigate the joined behaviours of tendon and pennation angle during maximal isometric contractions. A musculotendon model of the human soleus muscle was simulated as a function of ankle joint position, which determines the soleus length. Analysis of the respective values of tendon length and pennation angle for various musculotendon lengths showed that the primary effects of tendon elasticity and pennation angle variation were to reduce the fibre length variations by absorption of the musculotendon lengthening. The efficiency of this reduction process was the highest at short soleus lengths and principally related to tendon length variations. Finally…
Mechanical and neural stretch responses of the human soleus muscle at different walking speeds
2009
During human walking, a sudden trip may elicit a Ia afferent fibre mediated short latency stretch reflex. The aim of this study was to investigate soleus (SOL) muscle mechanical behaviour in response to dorsiflexion perturbations, and to relate this behaviour to short latency stretch reflex responses. Twelve healthy subjects walked on a treadmill with the left leg attached to an actuator capable of rapidly dorsiflexing the ankle joint. Ultrasound was used to measure fascicle lengths in SOL during walking, and surface electromyography (EMG) was used to record muscle activation. Dorsiflexion perturbations of 6 deg were applied during mid-stance at walking speeds of 3, 4 and 5 km h(-1). At eac…