The dynamics of two-dimensional viscous vesicles in shear flow, with different fluid viscosities etain and etaout inside and outside, respectively, is studied using mesoscale simulation techniques. Besides the well-known tank-treading and tumbling motions, an oscillatory swinging motion is observed in the simulations for large shear rate. The existence of this swinging motion requires the excitation of higher-order undulation modes (beyond elliptical deformations) in two dimensions. Keller-Skalak theory is extended to deformable two-dimensional vesicles, such that a dynamical phase diagram can be predicted for the reduced shear rate and the viscosity contrast etain/etaout. The simulation results are found to be in good agreement with the theoretical predictions, when thermal fluctuations are incorporated in the theory. Moreover, the hydrodynamic lift force, acting on vesicles under shear close to a wall, is determined from simulations for various viscosity contrasts. For comparison, the lift force is calculated numerically in the absence of thermal fluctuations using the boundary-integral method for equal inside and outside viscosities. Both methods show that the dependence of the lift force on the distance ycm of the vesicle center of mass from the wall is well described by an effective power law ycm(-2) for intermediate distances 0.8Rp< approximately ycm< approximately 3Rp with vesicle radius Rp. The boundary-integral calculation indicates that the lift force decays asymptotically as 1/[ycm ln(ycm)] far from the wall.

There are no data from prospective studies concerning the treatment of isolated calf muscle vein thrombosis (soleal and gastrocnemial muscle veins), found in 20-40% of patients with lower extremity thrombosis of the calf. We investigated the outcome in two cohorts of consecutive patients, the first receiving low-molecular-weight heparin for 10 days at therapeutic doses and compression therapy; the second cohort, compression therapy alone. In patients on therapeutic heparin (n = 52), no progression to deep vein thrombosis occurred [0%; 95% confidence interval (CI), 0-6.8%]. Patients without anticoagulation (n = 32) showed a statistically significant higher percentage of progression into the deep calf veins (25%; 95% CI, 11.5-43.4%) as well as recurrent muscle vein thrombosis. No symptomatic pulmonary embolism or bleeding event occurred; one patient died in each group, both related to malignancy. The data suggest a need for short-term anticoagulation in such patients to prevent further thromboembolic complications. Randomized prospective studies are now warranted in a larger study population.

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