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SummaryRecently a new hemostatic disorder has been described which appears to be an important risk factor for familial thromboembolism. The disorder is characterized by a poor anticoagulant response to activated Protein C (APC) and has been shown to be due to lack of an APC cofactor activity which is a property of factor V.A kit for determining the response of plasma samples towards addition of APC in an APTT-based assay - COATEST APC Resistance -has been evaluated on 35 coagulation instruments in a multicenter study involving 32 laboratories. A lyophilized normal plasma and identical plasma aliquots from 20 individuals, one of whom had a borderline resistance to APC, were analysed in each laboratory and the sensitivity of each plasma to APC was determined as the ratio between the clotting times obtained in the presence and absence of APC (APC ratio).The plasma from the individual with a borderline resistance to APC activity was correctly classified as the lowest responder in each laboratory, with an APC ratio in the range 1.6-2.4. In comparison, plasmas from individuals with a pronounced response to APC activity resulted in APC ratios above 3.4 in most cases. Interestingly, although the actual APT time for a plasma from a given individual showed a more than 10 s difference due to the type of instrumentation used, the variation in the APC ratio was limited. A similar discrimination was also obtained from evaluation of the actual prolongation of the clotting time in the presence of APC.The intra-laboratory coefficient of variation for the clotting times were on average 2.0% and 3.9% in the absence and presence of APC, respectively, indicating that the precision for the prolonged clotting times obtained in the presence of APC is sufficient to allow a safe assignment of the APC response. The APC ratio for the lyophilized normal plasma was 2.7 ± 0.2 (2 S.D.) illustrating a narrow distribution between instruments which shows the feasibility of including such plasma for assay validation. Altogether, the results indicate that all the coagulation instruments included in the study can be used for detection of individuals with resistance to APC activity through determination of the APC ratio or the prolongation time.

X-ray magnetic circular dichroism at the Er M4,5 edge is used to study the switching behavior of the hard ErFe2 layers in an epitaxial [ErFe2(70{\AA})/YFe2 (150{\AA})]{\times}25 exchange-spring superlattice. Magnetic hysteresis loops for the Er magnetization, at temperatures T < 200 K, reveal a switching behavior with a single type of irreversible switch corresponding to vertical exchange spring states. Experiments at T > 200 K reveal a crossover to a regime with two types of switching processes. Computational modelling for this system gives a semi-quantitative agreement with the experiment and reveals that the observed high temperature switching behavior is due to a spin-flop like reorientation transition. In contrast to conventional spin-flop transitions in antiferromagnets, in this exchange spring system the increase in anisotropy energy of the hard magnetic layers is overcome by the decrease in Zeeman energy of the soft layers. Computational studies also reveal the presence of transitions between vertical exchange spring and spin-flop states with a first-order character as well as continuous transitions between these states., Comment: 10 Pages 5 Figures

Implanted 3.25 keV Ar+ ions have been used to modify the in-plane bulk anisotropy in thin films of epitaxially grown Laves phase YFe2. The magneto optical Kerr effect, vibrating sample magnetometry and computational modeling have been used to show that the dominant source of anisotropy changes from magnetoelastic in as-grown samples to magnetocrystalline in ion implanted samples. This change occurs at a critical fluence of order 1017 Ar+ ions cm-2. The change in source of the anisotropy is attributed to a relaxation of the strain inherent in the epitaxially grown thin-films. Atomic force microscopy shows that the samples' topography remains unchanged after ion implantation. The ability to control the dominant source of magnetic anisotropy without affecting the sample surface could have important consequences in the fabrication of patterned media for high use in density magnetic data storage devices., Comment: 8 pages, 4 images

Contains fulltext : 70239.pdf (Publisher’s version ) (Closed access) Flow-mediated dilatation (FMD) of the brachial and radial arteries is an important research tool for assessment of endothelial function in vivo, and is nitric oxide (NO) dependent. The leg skeletal muscle vascular bed is an important territory for studies in exercise physiology. However, the role of endothelial NO in the FMD response of lower limb arteries has never been investigated. The purpose of this study was to examine the contribution of NO to FMD in the superficial femoral artery in healthy subjects. Since physical inactivity may affect endothelial function, and therefore NO availability, spinal cord-injured (SCI) individuals were included as a model of extreme deconditioning. In eight healthy men (34 +/- 13 years) and six SCI individuals (37 +/- 10 years), the 5 min FMD response in the superficial femoral artery was assessed by echo-Doppler, both during infusion of saline and during infusion of the NO synthase blocker N(G)-monomethyl-L-arginine (L-NMMA). In a subset of the controls (n = 6), the 10 min FMD response was also examined using the same procedure. The 5 min FMD response in controls (4.2 +/- 0.3%) was significantly diminished during L-NMMA infusion (1.0 +/- 0.2%, P < 0.001). In SCI, L-NMMA also significantly decreased the FMD response (from 8.2 +/- 0.4% during saline to 2.4 +/- 0.5% during L-NMMA infusion). The hyperaemic flow response during the first 45 s after cuff deflation was lower in both groups during infusion of L-NMMA, but the effect of L-NMMA on FMD persisted in both groups after correction for the shear stress stimulus. The 10 min FMD was not affected by L-NMMA (saline: 5.4 +/- 1.6%, L-NMMA: 5.6 +/- 1.5%). Superficial femoral artery FMD in response to distal arterial occlusion for a period of 5 min is predominantly mediated by NO in healthy men and in the extremely deconditioned legs of SCI individuals.

We study the interactions of the vortex lattice with a periodic square array of holes in a superconducting Nb film. Using high resolution magnetic field measurements of electrical losses, extremely narrow states with a magnetic field width reaching 1% of the matching field value are found at the commensurate points. They are accompanied by pronounced harmonic generation in response to ac modulation of the magnetic field or current. We relate these sharp anomalies to a locked commensurate state of the Mott insulator type., Comment: 7 pages, 4 figures

Magnetization and magnetoresistance measurements are reported for antiferromagnetically coupled DyFe$_2$/YFe$_2$ multilayers in fields up to 23 T. We demonstrate that the formation of short exchange springs (~ 2 nm) in the magnetically soft YFe$_2$ layers results in a giant magneto-resistance as high as 32% in the spring region. It is shown that both the magnitude of the effect, and its dependence on magnetic field, are in good agreement with the theory of Levy and Zhang for giant magnetoresistance due to domain wall like structures., Comment: 4 pages, 4 figures, submitted to Phys. Rev. Lett

I read with much interest the article of Derksen et al in the January issue of the Annals of the Rheumatic Diseases .1 The authors gave a detailed introduction to the difficult field of treatment of pregnant patients with antiphospholipid syndrome (APS). Despite the presence of only a limited amount of data from controlled studies the authors gave helpful recommendations for the daily management of these patients. However, there is a major concern with which I would like to deal. As we know the success of treatment of APS with oral anticoagulants very much depends on the strictness with which the dose is adjusted to the …

Haemodynamic side effects of antilymphocyte serum (ALS) have been studied in six dogs treated with equine anti-dog ALS. All animals responded with a severe but transient reduction of cardiac output and, in most cases, a drop in aortic pressure. This effect is best explained by a direct negative inotropic action followed by secondary vasoconstriction. An indirect effect of ALS by release of cardiotoxic substances from damaged blood cells seems to be a more probable explanation than a direct action of ALS on cardiac cell membranes.

Summary • Expansins are cell wall proteins required for cell enlargement and cell wall loos- ening during many developmental processes. The involvement of the Petunia hybrida expansin A1 (PhEXPA1) gene in cell expansion, the control of organ size and cell wall polysaccharide composition was investigated by overexpressing PhEXPA1 in petunia plants. • PhEXPA1 promoter activity was evaluated using a promoter-GUS assay and the protein’s subcellular localization was established by expressing a PhEXPA1- GFP fusion protein. PhEXPA1 was overexpressed in transgenic plants using the cauliflower mosaic virus (CaMV) 35S promoter. Fourier transform infrared (FTIR) and chemical analysis were used for the quantitative analysis of cell wall polymers. • The GUS and GFP assays demonstrated that PhEXPA1 is present in the cell walls of expanding tissues. The constitutive overexpression of PhEXPA1 significantly affected expansin activity and organ size, leading to changes in the architecture of petunia plants by initiating premature axillary meristem outgrowth. Moreover, a significant change in cell wall polymer composition in the petal limbs of transgenic plants was observed. • These results support a role for expansins in the determination of organ shape, in lateral branching, and in the variation of cell wall polymer composition, probably reflecting a complex role in cell wall metabolism