Search results for " Biomedical"
showing 10 items of 480 documents
Pectin biopolymer mechanics and microstructure associated with polysaccharide phase transitions.
2019
Polysaccharide polymers like pectin can demonstrate striking and reversible changes in their physical properties depending upon relatively small changes in water content. Recent interest in using pectin polysaccharides as mesothelial sealants suggests that water content, rather than nonphysiologic changes in temperature, may be a practical approach to optimize the physical properties of the pectin biopolymers. Here, we used humidified environments to manipulate the water content of dispersed solution of pectins with a high degree of methyl esterification (high-methoxyl pectin; HMP). The gel phase transition was identified by a nonlinear increase in compression resistance at a water content …
Comparaison de la mesure des déformations de fantômes de l’aorte à partir d’image obtenues par IRM et stéréovision
2015
International audience; The study of the wall strain distribution could be helpful to improve the decision criterion for surgery of aortic aneurysm. Recently, numerical simulations can complete the data obtained from imaging measurement in order to develop reliable models. However, the used medical imaging tools are not experimentally validated, in metrological point of view. The aim of this study focused on accuracy and reliability of measurement obtained from kinetic MR sequences. The measures of deformations from MRI were compare to those obtained from stereovision system. Cylindrical phantom of silicone material similar to arterial behavior simulated a symmetric aneurysm was designed. A…
Reliability of Local Activation Waves Features to Characterize Paroxysmal Atrial Fibrillation Substrate During Sinus Rhythm
2020
[EN] Analysis of coronary sinus (CS) electrograms (EGMs) is vastly used for the assessment of the atrial fibrillation (AF) substrate. As a catheter consists of five dipoles (distal, mid-distal, medial, mid-proximal, proximal), results may vary upon the employed channel: myocardial contraction and bad contact are unavoidable factors affecting the recording. This work aims to specify the most reliable channels in catching AF dynamics, using 44 multichannel bipolar CS recordings in sinus rhythm (SR) of paroxysmal AF with 1-5 minutes duration. Local activation waves (LAWs) were detected and main features obtained: duration, amplitude, area and correlation between dominant morphologies of each c…
Photoplethysmography in dogs and cats: a selection of alternative measurement sites for a pet monitor.
2018
Objective Photoplethysmography (PPG) is an increasingly popular health and well-being tool for monitoring heart rate and oxygen saturation. Due to the pigmentation and hairiness of dogs and cats, a pulse oximeter is routinely placed solely on the tongue. As this approach is feasible only for pet monitor use during surgical procedures, we investigate PPG signal quality on several other measurement sites that would be better tolerated by conscious animals. Approach Acquired PPG signals are analyzed by four signal quality indices: mean baseline, signal power, kurtosis, and tolerance score. Main results In dogs, the metacarpus and tail can be substituted for oral pulse oximeter placement since …
Circadian rhythms in ischaemic heart disease
2022
Abstract Circadian rhythms are internal regulatory processes controlled by molecular clocks present in essentially every mammalian organ that temporally regulate major physiological functions. In the cardiovascular system, the circadian clock governs heart rate, blood pressure, cardiac metabolism, contractility, and coagulation. Recent experimental and clinical studies highlight the possible importance of circadian rhythms in the pathophysiology, outcome, or treatment success of cardiovascular disease, including ischaemic heart disease. Disturbances in circadian rhythms are associated with increased cardiovascular risk and worsen outcome. Therefore, it is important to consider circadian rhy…
Interictal cardiorespiratory variability in temporal lobe and absence epilepsy in childhood
2015
It is well known that epilepsy has a profound effect on the autonomic nervous system, especially on the autonomic control of heart rate and respiration. This effect has been widely studied during seizure activity, but less attention has been given to interictal (i.e. seizure-free) activity. The studies that have been done on this topic, showed that heart rate and respiration can be affected individually, even without the occurrence of seizures. In this work, the interactions between these two individual physiological variables are analysed during interictal activity in temporal lobe and absence epilepsy in childhood. These interactions are assessed by decomposing the predictive information …
An emotional contribution to the Festschrift of the Journal of Biomaterials Science for Teiji Tsuruta
2017
AbstractIt is a honor for me to contribute to the ‘Festschrift for Teiji Tsuruta’! Being old, it is much easier for me to look back than to think ahead. Thus, please allow me to make a few ‘historical remarks’ about Biomaterials and Biotechnology, long before Science stepped in. Remarks about Georg Christoph Lichtenberg, the Gottinger physicist and philosopher, and his relation to Teiji Tsuruta. And talking about him as teacher, one cannot do it without looking at Hermann Staudinger and his dreams.
Crosslinked α,β-Polyasparthydrazide Micromatrices for Controlled Release of Anticancer Drugs
1995
The preparation of new hydrogels by the reaction of α,β- polyasparthydrazide and glutaraldehyde is reported. A different crosslinking degree was obtained by varying the ratio crosslinking agent/polymer which influenced the swelling behavior of the gel. 5-Fluorouracil, was incorporated into the matrices during the crosslinking reaction and in vitro release studies were performed in simulated gastric juice (pH 1.1) and pH 7.4 buffer solution. The hydrogels prepared were chemically stable in the dissolution media. The observed data show the potential application of these new matrices for peroral administration of anticancer agents.
Polyphosphoester surfactants as general stealth coatings for polymeric nanocarriers
2020
Opsonization of nanocarriers is one of the most important biological barriers for controlled drug delivery. The typical way to prevent such unspecific protein adsorption and thus fast clearance by the immune system is the covalent modification of drug delivery vehicles with poly(ethylene glycol) (PEG), so-called PEGylation. Recently, polyphosphoesters (PPEs) were identified as adequate PEG substitutes, however with the benefits of controllable hydrophilicity, additional chemical functionality, or biodegradability. Here, we present a general strategy by non-covalent adsorption of different nonionic PPE-surfactants to nanocarriers with stealth properties. Polyphosphoester surfactants with dif…
Poly(lactic acid)/carvacrol-based materials: preparation, physicochemical properties, and antimicrobial activity
2020
The current demand for new antimicrobial systems has stimulated research for the development of poly(lactic acid)/carvacrol (PLA/CAR)-based materials able to hinder the growth and spread of microorganisms. The eco-friendly characteristics of PLA and cytocompatibility make it very promising in the perspective of green chemistry applications as material for food and biomedical employments. The broad-spectrum biological and pharmacological properties of CAR, including antimicrobial activity, make it an interesting bioactive molecule that can be easily compounded with PLA by adopting the same techniques as those commonly used for PLA manufacturing. This review critically discusses the most comm…