| 1. |
- Kvitting, J.P., et al.
(författare)
-
Analysis of human myocardial dynamics using virtual markers based on magnetic resonance imaging
- 2010
-
Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 30:1, s. 23-29
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Myocardial dynamics are three-dimensional (3D) and time-varying. Cineradiography of surgically implanted makers in animals or patients is accurate for assessing these events, but this invasive method potentially alters myocardial motion. The aim of the study was to quantify myocardial motion using magnetic resonance imaging (MRI) and hence to provide a non-invasive approach to characterize 3D myocardial dynamics. Methods: Myocardial motion was quantified in ten normal volunteers by tracking the Lagrangian motion of individual points (i.e. virtual markers), based on time-resolved 3D phase-contrast MRI data and Fourier tracking. Nine points in the myocardium were tracked over the entire cardiac cycle, allowing a wire frame model to be generated and systolic and diastolic events identified. Results: Radius of curvature of the left ventricular (LV) wall was calculated from the virtual markers; the ratio between the anterior–posterior (AP) and septal–lateral (SL) walls in the LV shows an oval shape of the apical short axis plane at end systole (ES) and more circular at end diastole (ED). The AP/SL ratio for the basal plane shows an oval shape at ES and ED. We found that the rotation of the basal plane in ES was less compared to the apical plane [−2·0 ± 2·2 versus 4·1 ± 2·6 degrees (P<0·005)]. The apical plane rotated counter clock wise as viewed from the apex. Conclusion: This new non-invasive tool, despite current limitations in temporal and spatial resolution, may provide a comprehensive set of virtual myocardial markers throughout the entire LV without the confounding effects introduced by surgical implantation.
|
|
| 2. |
- Sigfridsson, Kalle, 1964, et al.
(författare)
-
Usefulness of a Nanoparticle Formulation to Investigate Some Hemodynamic Parameters of a Poorly Soluble Compound
- 2011
-
Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 1520-6017 .- 0022-3549. ; 100:6, s. 2194-2202
-
Tidskriftsartikel (refereegranskat)abstract
- Drug solubility is an important issue when progressing investigational compounds into clinical candidates. The present paper describes the development and characterization of a nanosuspension that was formulated to overcome problems with poor water solubility and possible adverse events caused by cosolvent mixtures, using ticagrelor as a model compound. A homogeneous nanosuspension of ticagrelor was formed using a wet milling approach, which yielded particle sizes around 230 nm. The nanosuspensions were chemically stable for at least 10 months at both room temperature and when refrigerated, and physically (i.e., particle size) stable for at least 10 months under refrigeration, and approximately 3 years at room temperature and when frozen. One rat model and two dog models were used to assess the pharmacokinetics and hemodynamic-related effects following intravenous administration of nanoparticles. There were no biologically consistent or dose-dependent effects of the nanoparticles on the hemodynamic parameters tested, that is, heart rate, mean aortic pressure, cardiac output, left femoral artery blood flow, or cardiac inotropy (measured as max dP/dt). In conclusion, a stable ticagrelor nanosuspension formulation was developed, suitable for intravenous administration. At the doses evaluated, this formulation was without hemodynamic effects in three sensitive preclinical models. (C) 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:2194-2202, 2011
|
|
