787-5 Systemic Effect of Ramipril on Endothelin, but not on Elcosanoid Levels in Patients with Coronary Artery Disease

Study aimNeurohumoral effects of ramipril (R) alone or in combination with isosorbide dinitrate (ISDN) compared to ISDN or placebo.Study designPlacebo-controlled double-blind parallel group trial.Methods32 patients with coronary artery disease (CAD) received placebo, R5mg, ISDN 20mg slow release b.i.d. or R+ISDN for one week. A 24 hour kinetic profile of ramipril and its metabolite, of ace activity (ACE-A) and of related hormones (renin and aldosterone), of endothelin and of prostaglandins (PG), thromboxane B2 (TXB2), PGF2a, 6-keto PGF1a, the stable metabolite of prostacyclin (PGI2-M) was studied after the first dose. Measurements were repeated after 8 days of treatment before and 3 hours after the morning dose.ResultsHormone measurements are presented as means of percent difference of patients treated with R (n=16) vs. those without ace-inhibitor (n=16).Time (hrs)0123468240–83–8Ramipril (mg/l)08543210.417Ramiprilat (mg/l)0611108751214ACE-A (%)-6-78-95-98-98-97-96-80-82-98Aldosteron (%)9-5-31-34-21-27-23-34--Renin (%)-9-771913175332--Endothelin (%)-17-13-25-19-16-15-40--TXB2 (%)41045-5012-3PGF2a (%)101700-8-22-9PGI2-M (%)70-38--59-1-713-=not done; significant differences are printed in italics (two-tailed t-test)A single oral dose of 5mg R reduced ACE activity (p<0.001), decreased aldosterone and increased renin (p<0.1). R did not influence plasma levels of the vasoconstricting (TXB2, PGF2a) or vasodilating (PGI2-M) eicosanoid mediators, but decreased endothelin (p<0.1).ConclusionR, in a dose that results in significant systemic inhibition of the renin angiotensin aldosteron system, does not induce measurable changes of circulating eicosanoid concentrations, but seems to diminish systemic release of endothelin

Kolloidisten suspensioiden online -analysointi: tutkimuksesta liiketoimintaa

publishedVersio

Micromechanical modeling of failure behavior of metallic materials

Microstructural and micromechanical modeling is arising as a key material modeling technique providing numerical modeling capabilities with an improved description of critical material features and mechanisms. Material characteristics such as microstructural morphologies, individual phases and defects can be included explicitly in numerical models and their significance to the material properties and performance measures of interest quantified. Similarly, mechanisms dependent on microstructural scale mechanisms such as polycrystalline plasticity can be modeled accounting for such anisotropic phenomena, and as such, improved accuracy can be reached with respect to design critical mechanisms such as cleavage fracture and initiation of short fatigue cracks. Micromechanical modeling deals with evaluating and modeling material failure relevant mechanisms at the scale of the material microstructure. Typical example is material damage with respect to ductile or brittle fracture, fatigue damage and crack initiation, or for example analysis of material wear which can be seen as a more intricate failure process where several mechanisms interact across multiple spatial scales. Current work addresses some typical failure mechanisms of metallic materials at the scale of the material microstructure. Case studies are discussed where micromechanical modeling is employed to assess material failure with different damage mechanical models and concepts. The basis in all is the description of material deformation by crystal plasticity constitutive models. Two treatments of damage are considered: direct coupling of the crystal plasticity model to a damage mechanical approach and a simpler methodology where a non-coupled evaluation of damage parameters is considered. The use cases consist of fracture, fatigue and wear problems from problems targeting both design of new materials, optimization of material solutions and improved design of products and components

Monitoring Arterial Pulse Waves With Synchronous Body Sensor Network

acceptedVersionPeer reviewe

Self-powered, high sensitivity printed e-tattoo sensor for unobtrusive arterial pulse wave monitoring

Self-powered, highly unobtrusive, low-cost and accurate arterial pulse wave monitoring devices need to be developed to enable cost-efficient monitoring of entire cardiovascular disease risk groups. We report the development of a scalable fabrication process for a highly unobtrusive piezoelectric ultra-thin (t ~ 4,2 µm) e-tattoo arterial pulse wave sensor which utilizes only transparent and biocompatible polymer-based materials. The ferroelectric performance of the ultra-thin P(VDF-TrFE) material layer is optimized through the use of crosslinked PEDOT:PSS electrodes; this results in ~70 % and ~34 % improvements in remanent polarization (Pr) and coercive field (Ec), respectively, when compared to the sensors with pristine PEDOT:PSS electrodes. The ultra-thin form factor enables access to the high bending mode sensitivity of the P(VDF-TrFE) material layer; the maximum sensitivity value achieved in uniaxial and multiaxial bending is ~1700 pC N-1, which is ~50 times higher than the measured normal mode sensitivity. The increased sensitivity is linked to a specific set of direct piezoelectric coefficients using combination of experimental results, statistical analysis and finite element modeling. Finally, the accuracy of the e-tattoo sensor is demonstrated in the non-invasive measurement of radial artery pulse wave by comparing the signal to that obtained with reference device from 7 study subjects.publishedVersionPeer reviewe

Self-Powered, Ultrathin, and Transparent Printed Pressure Sensor for Biosignal Monitoring

Ultrathin sensing devices utilizing piezoelectric materials have emerged as potential candidates to develop highly skin-conformable and energy-efficient continuous biosignal monitoring systems. However, biocompatible, cost-efficient, and simple fabrication processes still need to be investigated to enable wider adoption of such devices. This study proposes a simple two-step printing process for the fabrication of a piezoelectric biosignal sensor that utilizes readily available and biocompatible polymer-based materials for the substrate (i.e., Parylene-C), electroactive layer (i.e., poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE)), and interdigitated electrodes (i.e., poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)). The proposed interdigitated electrode architecture improves upon the conventional metal–insulator–metal architecture by (1) increasing the thickness-normalized output voltage and (2) enabling the detection of bending orientation. The performance of the proposed sensor structure is demonstrated with the measurement of the arterial pulse waveform signal and limb movement detection. The presented results pave the way for cost-effective and continuous unobtrusive on-skin biosignal monitoring.publishedVersionPeer reviewe

A Fully Printed Ultra-Thin Charge Amplifier for On-Skin Biosignal Measurements

In this contribution, we propose a fully printed charge amplifier for on-skin biosignal measurements. The amplifier is fabricated on an ultra-thin parylene substrate and consists of organic transistors, integrated bias and feedback resistors, and a feedback capacitor. The fabrication process utilizes inkjet-printed Ag ink for source, drain, gate, and capacitor electrode metallization as well as for the interconnects between the amplifier elements. Dispensed polystyrene, 2,7-dihexyl-dithieno[2,3-d:2',3'-d']benzo[1,2-b:4,5-b']dithiophene (PS:DTBDT-C6), is used as the transistor channel material, dispensed poly(3-hexylthiophene) (P3HT) as the high-resistivity material for the printed resistors, and parylene as the capacitor dielectric. A pass band optimized for pulse-wave measurement (60 mHz to 36 Hz) is achieved with a maximum charge amplification of 1.6 V/nC. To demonstrate the potential of the proposed printed amplifier, a radial arterial pulsewave signal recorded with a printed piezoelectric poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE) sensor was fed to it and the output was analyzed to quantify the similarity of the pulse-wave features calculated from the original signal and the amplifier output. The amplified signal contains all the essential features of a pulse wave, such as both systolic waves, the dicrotic notch, and diastolic wave, which enable the accurate derivation of the clinically relevant indices utilized in the evaluation of vascular health.acceptedVersionPeer reviewe