Duplex assessment of venous reflux and chronic venous insufficiency: The significance of deep venous reflux

AbstractPurpose: This study was undertaken to examine the role of superficial and deep venous reflux, as defined by duplex-derived valve closure times (VCTs), in the pathogenesis of chronic venous insufficiency.Methods: Between January 1992 and November 1995, 320 patients and 500 legs were evaluated with clinical examinations and duplex scans for potential venous reflux. VCTs were obtained with the cuff deflation technique with the patient in the upright position. Imaging was performed at the saphenofemoral junction, the middle segment of the greater saphenous vein, the lesser saphenous vein, the superficial femoral vein, the profunda femoris vein, and the popliteal vein. Not all patients had all segments examined because tests early in the series did not examine the profunda femoris or lesser saphenous vein and because some patients had previous ligation and stripping or venous thrombosis. VCTs were examined for individual segment reflux, grouped into superficial and deep systems, and then correlated with the clinical stage as defined by the SVS/ISCVS original reporting standards in venous disease. Segment reflux was considered present if the VCT was greater than 0.5 seconds, and system reflux was considered present if the sum of the segments was greater than 1.5 seconds. Between-group differences were analyzed with analysis of variance and post hoc tests where appropriate.Results: Sixty-nine limbs studied were in class 0, 149 limbs were in class 1, 168 limbs were in class 2, and 114 limbs were in class 3. VCTs in the superficial veins were significantly lower in class 0 than in the other clinical classes. There was no difference in superficial reflux in the symptomatic limbs (classes 1 to 3). Reflux VCTs in the superficial femoral and popliteal veins increased as the clinical symptoms progressed, with a significant increase in class 3 ulcerated limbs when compared with nonulcerated limbs. The incidence of deep venous reflux was 60% in class 3 limbs, compared with 29% in class 2 limbs, whereas the incidence of superficial venous reflux did not differ among the symptomatic limbs. Isolated superficial femoral and popliteal vein reflux was uncommon, even in class 3 limbs, but combined superficial femoral and popliteal vein reflux was found in 53% of class 3 limbs, compared with 18.5% of class 2 limbs.Conclusions: Reflux in the deep venous system plays a significant role in the progression of chronic venous insufficiency. Deep system reflux increases as clinical changes become more severe, with significant axial reflux contributing to ulcer formation. (J Vasc Surg 1996;24:755-62.

Cardiovascular roles of estrogen receptors: insights gained from knockout models

The effects of estrogen are mediated through two functionally distinct receptors, estrogen receptor α (ER- α ), and estrogen receptor β (ER- β ), both of which are expressed in the cardiovascular system. The etiology of cardiovascular disease is believed to result in part from the loss of endogenous estrogen, indicating that estrogen and its receptors may play important roles in the prevention of cardiovascular disease in women

Deuterium retention and erosion in liquid Sn samples exposed to D2 and Ar plasmas in GyM device

The use of tin (Sn) as a liquid metal for plasma facing components has been recently proposed as a solution to the high heat load issue on the divertor target plates in nuclear fusion reactors. Due to its low vapor pressure, low reactivity with hydrogen and good resilience to neutron impact, tin is a good candidate as plasma facing component. However its high atomic number poses concerns about plasma contamination.In this paper two fundamental aspects have been investigated: deuterium retention and erosion fluxes from the Sn surface towards the plasma. The samples were exposed to plasma inside the linear machine GyM in magnetic cusp configuration. This setup permits to expose free liquid specimens without the need for the Capillary Porous System. Moreover it permits to lower the magnetic field in order to increase Sn Larmor radius and consequently limit Sn re-deposition in erosion experiments.Ex-situ analyses by ion beam diagnostics on solid samples exposed to deuterium plasma have proved that the amount of retained atomic deuterium is very low, approximately 0.18 at% estimated by Nuclear Reaction Analysis and 0.25 at% estimated by Elastic Recoil Detection Analysis.In the framework of erosion studies, the spectroscopic parameter S/XB was evaluated in Ar plasma for the SnI line at 380.1 nm by Optical Emission Spectroscopy and mass loss measurements in the 5–11 eV Te range, at a density ne ∼ 1.5 × 1011 cm−3. An average value of 150 ± 23 was obtained. Keywords: Liquid metals, Deuterium retention, Erosion, Double-cusp magnetic configuration, Ion beam diagnostics, S/XB spectroscopic paramete

Overview of power exhaust experiments in the COMPASS divertor with liquid metals

Power handling experiments with a special liquid metal divertor module based on the capillary porous system technology were performed in the tokamak COMPASS. The performance of two metals (Li and LiSn alloy) were tested for the first time in a divertor under ELMy H-mode conditions. No damage of the capillary mesh and a good exhaust capability were observed for both metals in two separate experiments with up to 12 MW/m(2) of deposited perpendicular, inter-ELM steady-state heat flux and with ELMs of relative energy similar to 3% and a local peak energy fluence at the module similar to 15 kJ.m(-2). No droplets were directly ejected from the mesh top surface and for the LiSn experiment, no contamination of the core and SOL plasmas by Sn was observed. The elemental depth profile analysis of 14 stainless-steel samples located around the vacuum vessel for each experiment provides information about the migration of evaporated/redeposited liquid elements

D-shaped configurations in FTU for testing liquid lithium limiter: Preliminary studies and experiments

The feasibility of getting "D" shaped plasma configurations in FTU, with a possible X point close to the first wall, has been investigated with the aim of achieving an H-mode regime in this machine. This regime could allow both evaluating the thermal effects on the liquid lithium limiter due to the possible Edge Localized Modes and studying the L-H transition properties in low recycling conditions due to the presence of lithium.. An alternative design for the magnetic system in FTU has been also proposed, to realize an X-point inside the plasma chamber, close to the Liquid Lithium Limiter.Preliminary experiments with elongated configurations and limited ECRH additional heating power did not allowed approaching the L-H transition but they were used to develop a proper elongation control. This controller allowed guaranteeing the vertical stability in elongated configurations despite the reduced power available for the horizontal field coils in FTU. The elongation was stably keep over 1.2, while the lithium limiter was very close to the last close flux surface. Neither limiter damages nor plasma pollution were observed in these configurations.A possible alternative connection of the poloidal field coils in FTU is here proposed, with the aim of achieving a true X-point configuration with a magnetic single null well inside the plasma chamber and strike points on the lithium limiter. A preliminary assessment of this design allowed estimating the required power supply upgrade and showed its compatibility with the existing mechanical structure and cooling system, at least for plasmas with current up to 300 kA and flat-top duration up to 4s. Keywords: FTU, Liquid lithium limiter, L-H transition, X-point, Plasma elongatio

Three-dimensional steep wave impact on a vertical cylinder

In the present study we investigate the 3-D hydrodynamic slamming problem on a vertical cylinder due to the impact of a steep wave that is moving with a steady velocity. The linear theory of the velocity potential is employed by assuming inviscid, incompressible fluid and irrotational flow. As the problem is set in 3-D space, the employment of the Wagner condition is essential. The set of equations we pose, is presented as a mixed boundary value problem for Laplace's equation in 3-D. Apart from the mixed-type of boundary conditions, the problem is complicated by considering that the region of wetted surface of the cylinder is a set whose boundary depends on the vertical coordinate on the cylinder up to the free-surface. We make some simple assumptions at the start but otherwise we proceed analytically. We find closed-form relations for the hydrodynamic variables, namely the time dependent potential, the pressure impulse, the shape of the wave front (from the contact point to beyond the cylinder) and the slamming force

The role of amputation as an outcome measure in cellular therapy for critical limb ischemia: implications for clinical trial design

<p>Abstract</p> <p>Background</p> <p>Autologous bone marrow-derived stem cells have been ascribed an important therapeutic role in No-Option Critical limb Ischemia (NO-CLI). One primary endpoint for evaluating NO-CLI therapy is major amputation (AMP), which is usually combined with mortality for AMP-free survival (AFS). Only a trial which is double blinded can eliminate physician and patient bias as to the timing and reason for AMP. We examined factors influencing AMP in a prospective double-blinded pilot RCT (2:1 therapy to control) of 48 patients treated with site of service obtained bone marrow cells (BMAC) as well as a systematic review of the literature.</p> <p>Methods</p> <p>Cells were injected intramuscularly in the CLI limbs as either BMAC or placebo (peripheral blood). Six month AMP rates were compared between the two arms. Both patient and treating team were blinded of the assignment in follow-up examinations. A search of the literature identified 9 NO-CLI trials, the control arms of which were used to determine 6 month AMP rates and the influence of tissue loss.</p> <p>Results</p> <p>Fifteen amputations occurred during the 6 month period, 86.7% of these during the first 4 months. One amputation occurred in a Rutherford 4 patient. The difference in amputation rate between patients with rest pain (5.6%) and those with tissue loss (46.7%), irrespective of treatment group, was significant (p = 0.0029). In patients with tissue loss, treatment with BMAC demonstrated a lower amputation rate than placebo (39.1% vs. 71.4%, p = 0.1337). The Kaplan-Meier time to amputation was longer in the BMAC group than in the placebo group (p = 0.067). Projecting these results to a pivotal trial, a bootstrap simulation model showed significant difference in AFS between BMAC and placebo with a power of 95% for a sample size of 210 patients. Meta-analysis of the literature confirmed a difference in amputation rate between patients with tissue loss and rest pain.</p> <p>Conclusions</p> <p>BMAC shows promise in improving AMP-free survival if the trends in this pilot study are validated in a larger pivotal trial. The difference in amp rate between Rutherford 4 & 5 patients suggests that these patients should be stratified in future RCTs.</p

Muon detection in electron-positron annihilation for muon collider studies

The investigation of the energy frontier in physics requires novel concept for future colliders. The idea of a muon collider is very appealing since it would aim to study particle collisions up to tens of TeV energy while offering a cleaner experimental environment with respect to hadronic colliders. One key element in the muon collider design is muon production with small emittance. Recently, the Low EMittance Muon Accelerator (LEMMA) collaboration has explored the close-to-threshold muon production by 45 GeV positron annihilating in a low Z material target. Muons are emerging with a natural small emittance. In this paper we describe the performance of a system of segmented absorbers with alternating active layers realized with fast Cherenkov detectors and a muon identification technique based on it. Passive layers were made of tungsten. Muons and electron beams data were collected in September 2018 at the H2 line in the North Area of the Conseil Européen pour la Recherche Nucléaire (CERN)