Function of von Willebrand factor after crossed bone marrow transplantation between normal and von Willebrand disease pigs: effect on arterial thrombosis in chimeras.

von Willebrand factor (vWF) is essential for the induction of occlusive thrombosis in stenosed and injured pig arteries and for normal hemostasis. To separate the relative contribution of plasma and platelet vWF to arterial thrombosis, we produced chimeric normal and von Willebrand disease pigs by crossed bone marrow transplantation; von Willebrand disease (vWD) pigs were engrafted with normal pig bone marrow and normal pigs were engrafted with vWD bone marrow. Thrombosis developed in the chimeric normal pigs that showed normal levels of plasma vWF and an absence of platelet vWF; but no thrombosis occurred in the chimeric vWD pigs that demonstrated normal platelet vWF and an absence of plasma vWF. The ear bleeding times of the chimeric pigs were partially corrected by endogenous plasma vWF but not by platelet vWF. Our animal model demonstrated that vWF in the plasma compartment is essential for the development of arterial thrombosis and that it also contributes to the maintenance of bleeding time and hemostasis

Changes in Doppler mitral inflow patterns during parabolic flight.

Aim of the study was to evaluate by transthoracic Doppler the alterations in mitral inflow velocity pattern caused by acute changes in loading conditions occurring during parabolic flights. Each parabola included normogravity (1 Gz, 1 min), mild hypergravity (1.8 Gz, 20 sec), microgravity (0 Gz, 24 sec) and mild hypergravity (1.8 Gz, 20 sec) phases. Pulsed-Doppler images were digitally acquired in 11 unmedicated subjects (46 +/- 5 years), in standing upright position and supine resting. Doppler profiles were semi-automatically traced and inflow parameters extracted and averaged onto three consecutive beats. Only in standing position, significant alterations during microgravity (p<0.05) were noted in several parameter

Changes in Doppler mitral inflow patterns during parabolic flight

Aim of the study was to evaluate by transthoracic Doppler the alterations in mitral inflow velocity pattern caused by acute changes in loading conditions occurring during parabolic flights. Each parabola included normogravity (1 Gz, 1 min), mild hypergravity (1.8 Gz, 20 sec), microgravity (0 Gz, 24 sec) and mild hypergravity (1.8 Gz, 20 sec) phases. Pulsed-Doppler images were digitally acquired in 11 unmedicated subjects (46 +/- 5 years), in standing upright position and supine resting. Doppler profiles were semi-automatically traced and inflow parameters extracted and averaged onto three consecutive beats. Only in standing position, significant alterations during microgravity (p<0.05) were noted in several parameter

Time-variant spectral analysis of heart rate variability during parabolic flight with and without LBNP

none7CAIANI EG; L. MAINARDI; BAILLIART O; CHOLLEY B; CERUTTI S; CAPDEROU A; VAIDA P.Caiani, ENRICO GIANLUCA; Mainardi, Luca; Bailliart, O; Cholley, B; Cerutti, Sergio; Capderou, A; Vaida, P

Quantification of left ventricular modification in weightlessness conditions from the spatio-temporal analysis of 2D echocardiographic images

none9Two-dimensional echocardiography (2DE) performed during flights with parabolic trajectory to simulate weightlessness provide a unique means to study left ventricular (LV) modifications in order to prevent post-flight orthostatic intolerance in astronauts. However, conventional analysis of 2DE is based on manual tracings, which depends on readers' experience. Accordingly, our aim was to objectively quantify from 2DE images the LV modifications relevant to different gravity levels, by applying a semi-automated level-set border detection technique. The algorithm validation was performed by comparing manual tracing results, obtained by two independent observers on twenty images, with the semi-automated measurements. To quantify LV modifications, three consecutive cardiac cycles were analyzed for each gravity phase (1Gz, 1.8Gz, 0Gz). The level-set procedure was applied frame-by-frame to detect the LV endocardial contours and obtain LV area versus time curves, from which end-diastolic (EDA) and end-systolic (ESA) areas were computed and averaged to compensate for respiratory variations. Linear regression (y=0.91x+1.47, r=0.99, SEE:0.80cm2) and Bland-Altman analysis (bias=–0.58cm2, 95% limits of agreement=±2.14cm2) showed excellent correlation between semi-automatic and manually traced values. Interobserver variability was 5.4%, while the inter-technique variability resulted in 4.1%. Modifications in LV dimensions during the parabola were found: compared to 1Gz values, EDA and ESA were significantly reduced at 1.8Gz of 8.8±5.5% and of 12.1±10.1% respectively, while during 0Gz EDA and ESA increased of 13.3±7.3% and of 11.6±5.1% respectively, due to abrupt changes in venous return. The proposed method resulted in fast and reliable estimations of LV dimensions, whose changes caused by different gravity conditions were objectively quantified.noneC. CORSI; LAMBERTI C.; S. CERUTTI; J.P. LAULOM; O. BAILLIART; B. CHOLLEY; A. CAPDEROU; P. VAIDA; E.G. CAIANIC. CORSI; LAMBERTI C.; S. CERUTTI; J.P. LAULOM; O. BAILLIART; B. CHOLLEY; A. CAPDEROU; P. VAIDA; E.G. CAIAN