Fibrinogen gamma ' increases the sensitivity to activated protein C in normal and factor V Leiden plasma
BLOOD
Authors: Omarova, Farida; de Willige, Shirley Uitte; Simioni, Paolo; Ariens, Robert A. S.; Bertina, Rogier M.; Rosing, Jan; Castoldi, Elisabetta
Abstract
Activated protein C (APC) resistance, often associated with the factor V (FV) Leiden mutation, is the most common risk factor for venous thrombosis. We observed increased APC resistance in carriers of fibrinogen gamma gene (FGG) haplotype 2, which is associated with reduced levels of the alternatively spliced fibrinogen gamma ' chain. This finding prompted us to study the effects of fibrinogen and its gamma ' chain on APC resistance. Fibrinogen, and particularly the gamma A/gamma ' isoform, improved the response of plasma to added APC in the thrombin generation-based assay. Similarly, a synthetic peptide mimicking the C-terminus of the fibrinogen gamma ' chain, which binds thrombin and inhibits its activities, greatly increased the APC sensitivity of normal and FV Leiden plasma, likely due to its ability to inhibit thrombin-mediated activation of FV and FVIII. Although the fibrinogen gamma ' peptide also inhibited protein C activation by the thrombin/thrombomodulin complex, it still increased the sensitivity of plasma to endogenously formed APC when thrombin generation was measured in the presence of soluble thrombomodulin. We conclude that fibrinogen, and particularly fibrinogen gamma ', increases plasma APC sensitivity. The fibrinogen gamma ' peptide might form the basis for pharmacologic interventions to counteract APC resistance.
FGG-NUFFT-Based Method for Near-Field 3-D Imaging Using Millimeter Waves
SENSORS
Authors: Kan, Yingzhi; Zhu, Yongfeng; Tang, Liang; Fu, Qiang; Pei, Hucheng
Abstract
In this paper, to deal with the concealed target detection problem, an accurate and efficient algorithm for near-field millimeter wave three-dimensional (3-D) imaging is proposed that uses a two-dimensional (2-D) plane antenna array. First, a two-dimensional fast Fourier transform (FFT) is performed on the scattered data along the antenna array plane. Then, a phase shift is performed to compensate for the spherical wave effect. Finally, fast Gaussian gridding based nonuniform FFT (FGG-NUFFT) combined with 2-D inverse FFT (IFFT) is performed on the nonuniform 3-D spatial spectrum in the frequency wavenumber domain to achieve 3-D imaging. The conventional method for near-field 3-D imaging uses Stolt interpolation to obtain uniform spatial spectrum samples and performs 3-D IFFT to reconstruct a 3-D image. Compared with the conventional method, our FGG-NUFFT based method is comparable in both efficiency and accuracy in the full sampled case and can obtain more accurate images with less clutter and fewer noisy artifacts in the down-sampled case, which are good properties for practical applications. Both simulation and experimental results demonstrate that the FGG-NUFFT-based near-field 3-D imaging algorithm can have better imaging performance than the conventional method for down-sampled measurements.