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Sample records for mechanical thrombectomy combined

  1. Septic thrombophlebitis: percutaneous mechanical thrombectomy and thrombolytic therapies.

    PubMed

    Kar, Subrata; Webel, Richard

    2014-01-01

    Suppurative thrombophlebitis (Lemierre's syndrome) of the internal jugular vein is a rare and sometimes fatal complication. It commonly occurs from oropharyngeal infections, peripheral lines, complications from dental procedures, gingivitis, or central venous catheterizations. Empiric antibiotics are the initial treatment of choice followed by thrombolytics or surgical thrombectomy in refractory cases. We present a case of septic thrombophlebitis of the right internal jugular vein from a peripherally inserted central venous catheter. We also review the current percutaneous mechanical thrombectomy and thrombolytics therapies for such a rare disorder. Mechanical thrombectomy includes rotational thrombectomy or rheolytic therapies. Devices include the Amplatz thrombectomy device (Microvena), the Arrow-Trerotola Percutaneous thrombolytic device (Arrow), and the Cragg-Casteneda thrombolytic brush (Microtherapeutics). Rheolytic therapies include Angiojet, the Hydrolyzer, and the Oasis Thrombectomy System. Percutaneous mechanical thrombectomy techniques include rotational fragmentation, aspiration or suction thrombectomy, and hydrodynamic thrombectomy. AngioJet catheters may be used for percutaneous embolectomy in conjunction with pulse spray techniques, which instill thrombolytics locally. Thrombolytics include streptokinase, urokinase, and recombinant-tissue plasminogen activator. Mechanical thrombectomy combined with thrombolytics provide optimal treatment results secondary to their complementary effects. Therefore, patients who are refractory to standard medical therapy and considered poor surgical candidates may benefit from combined percutaneous mechanical thrombectomy with thrombolytics to achieve superior results if no contraindications exist for thrombolytics.

  2. Combined use of stent angioplasty and mechanical thrombectomy for acute tandem internal carotid and middle cerebral artery occlusion

    PubMed Central

    Gao, Feng; Joyce Lo, WaiTing; Sun, Xuan; Xu, XiaoTong

    2015-01-01

    Purpose Tandem internal carotid and middle cerebral artery occlusion carries a grave prognosis, with intravenous and intra-arterial thrombolytics having low efficacy. Currently, endovascular therapy is a promising means for treatment in which the proximal carotid lesion can be treated with angioplasty and stenting, whilst mechanical thrombectomy can be used for the treatment of the distal occlusion. Two approaches can be used – the antegrade (proximal-to-distal) approach or the retrograde (distal-to-proximal) approach, although there has not yet been any consensus on which is the better approach. Case report We present two patients with tandem occlusions, one treated using the antegrade and one using the retrograde approach, with different revascularization outcomes, despite having similar functional outcome on follow-up. Conclusion The combined use of stent angioplasty and mechanical thrombectomy can be used to treat tandem occlusions, and with procedural modifications, the antegrade approach may more easily achieve technical success. PMID:26246102

  3. Mechanical thrombectomy using a combined CT/C-arm X-ray system

    PubMed Central

    Herweh, Christian; Pham, Mirko; Schönenberger, Silvia; Bösel, Julian; Ringleb, Peter A; Heiland, Sabine; Bendszus, Martin; Möhlenbruch, Markus

    2016-01-01

    Background Mechanical thrombectomy (MT) using stent-retrievers has been proven to be a safe and effective treatment in acute ischemic stroke (AIS), particularly in large vessel occlusion. Other than patient characteristics, time to recanalization is the most important factor linked to outcome. MT is usually performed in a dedicated angiography suite using a floor- and/or ceiling-mounted biplane angiographic system. Here we report our first experience of MT with a new combined CT and mobile C-arm X-ray device setup. Methods Patients with AIS underwent stroke imaging (non-contrast enhanced CT, CT perfusion, and CT angiography) using a commercially available 64-slice CT scanner which was modified for combined use with a C-arm system. In patients with large vessel occlusion, MT was conducted without further patient transfer within the CT imaging suite using a mobile C-arm X-ray device equipped with a 30×30 cm (12×12 inch), 1.5×1.5 k full-view flat detector which was positioned between the gantry and patient table. The safety and feasibility of this new system was assessed in preliminary patients. Results Angiographic imaging quality of the mobile C-arm was feasible and satisfactory for diagnostic angiography and MT. Using this setup, time between stroke imaging and groin puncture (picture-to-puncture time) was reduced by up to 35 min (including time for preparation of the patient such as intubation). Conclusions MT using a combined CT/C-arm system is safe and feasible. The potential advantages, particularly time saving and ensuing improvement in patient outcome, need to be assessed in a larger study. PMID:25935925

  4. Influence of a combined CT/C-arm system on periprocedural workflow and procedure times in mechanical thrombectomy.

    PubMed

    Pfaff, Johannes; Schönenberger, Silvia; Herweh, Christian; Pham, Mirko; Nagel, Simon; Ringleb, Peter Arthur; Heiland, Sabine; Bendszus, Martin; Möhlenbruch, Markus Alfred

    2017-09-01

    To achieve the fastest possible workflow in ischaemic stroke, we developed a CT/C-arm system, which allows imaging and endovascular treatment on the same patient table. This prospective, monocentric trial was conducted between October 2014 and August 2016. Patients received stroke imaging and mechanical thrombectomy under general anaesthesia (GA) or conscious sedation (CS) using our combined setup comprising a CT-scanner and a mobile C-arm X-ray device. Primary endpoint was time between stroke imaging and groin puncture. We compared periprocedural workflow and procedure times with the literature and a matched patient cohort treated with a biplane angiographic system before installation of the CT/C-arm system. In 50 patients with acute ischaemic stroke due to large-vessel occlusion in the anterior circulation, comparable recanalization rates were achieved by using the CT/C-arm setup (TICI2b-3:CT/C-arm-GA: 85.7%; CT/C-arm-CS: 90.9%; Angiosuite: 78.6%; p = 0.269) without increasing periprocedural complications. Elimination of patient transport resulted in a significant reduction of the time between stroke imaging and groin puncture: median, min (IQR): CT/C-arm-GA: 43 (35-52); CT/C-arm-CS: 39 (28-49); Angiosuite: 64 (48-74); p < 0.0001. The combined CT/C-arm system allows comparable recanalization rates as a biplane angiographic system and accelerates the start of the endovascular stroke treatment. • The CT/C-arm setup reduces median time from stroke imaging to groin puncture. • Mechanical thrombectomy using a C-arm device is feasible without increasing peri-interventional complications. • The CT/C-arm setup might be a valuable fallback solution for emergency procedures. • The CT/C-arm setup allows immediate control CT images during and after treatment.

  5. Mechanical Thrombectomy of Hemodialysis Fistulae and Grafts

    SciTech Connect

    Patel, Aalpen A. Tuite, Catherine M.; Trerotola, Scott O.

    2005-12-15

    In this article, the authors present approaches they use in performing dialysis access intervention-in particular clotted access. It is not meant to be a comprehensive review of dialysis access management. At our institution, mechanical thrombectomy is the primary mode of treatment for clotted hemodialysis access. We will present physical examination findings in clotted dialysis access and contraindications for mechanical thrombectomy in dialysis access. We will also discuss the devices for mechanical thrombectomy and the techniques we use. Finally, we will discuss the difficulties encountered in these procedures and their solutions.

  6. [Percutaneous mechanical thrombectomy by means of rotational thrombectomy. Current study situation].

    PubMed

    Lichtenberg, Michael

    2010-10-01

    Acute and subacute ischemia of the limbs is still one of the most frequent reasons for amputation. There are different therapy options for reperfusion therapy including balloon thrombectomy, local lysis and rotational thrombectomy. Balloon thrombectomy, the standard surgical treatment, has proven an effective tool for the treatment of acute vascular obstructions. Nevertheless technical problems and complications can occur. Localized lysis on the other hand could be time - consuming and cost intensive, requiring intensive care monitoring and reangiograms. To achieve a successful result, at least one lower limb artery or major collateral has to be reopened to establish a sufficient situation. During the last years considerable advances have been made in endovascular interventions for the treatment of acute and subacute limb ischemia. The Straub Rotarex is one of the modern peripheral mechanical thrombectomy device, which combines mechanical thrombus fragmentation and removal of the material using negative pressure. There are different clinical and experimental studies, which have shown promising results in restoring blood flow to the occluded vessels. Studies mainly exist for the lower extremities. Some case reports showed effective treatment of the subclavian and axillary arteries. The advantages of the Rotarex system is simple handling, a short intervention time and the avoidance of lytic substances with consequent reduced risk of hemorrhage complications. In this article an overview about the main Rotarex studies is given which analyzed the results of percutaneous rotational thrombectomy in patients with subacute an acute thrombotic occlusions in peripheral arteries.

  7. Mechanical Thrombectomy of Iliocaval Thrombosis Using a Protective Expandable Sheath

    SciTech Connect

    Truong, Tri H.; Spuentrup, Elmar; Staatz, Gundula; Wildberger, Joachim E.; Schmitz-Rode, Thomas; Nolte-Ernsting, Claus C.A.; Guenther, Rolf W.; Haage, Patrick

    2004-09-15

    We report a case of successful percutaneous treatment of a subacute ilio-caval venous thrombosis in a 64-year-old female patient by using a novel combination of a rotatory fragmentation device (percutaneous thrombectomy device: PTD) and large wire basket (temporary Guenther basket filter) under temporary caval filter protection using an expandable sheath. Because the patient had multiple myeloma with increased risk for contrast media-induced renal failure, the therapeutic angiographic procedure was performed without iodinated contrast medium. Non-contrast-enhanced MR venography (high-resolution True FISP) confirmed the effective thrombus removal by the percutaneous mechanical thrombectomy procedure.

  8. Successful Recanalization of Acute Superior Mesenteric Artery Thromboembolic Occlusion by a Combination of Intraarterial Thrombolysis and Mechanical Thrombectomy with a Carotid Filter

    SciTech Connect

    Zelenak, Kamil; Sinak, Igor; Janik, Jan; Mikolajcik, Anton; Mistuna, Dusan

    2013-06-15

    Acute superior mesenteric artery (SMA) occlusion is a life-threatening disease, and acute intestinal ischemia develops from the sudden decrease in perfusion to the intestines. The key to saving the patient's life is early diagnosis, and prompt revascularization of the SMA can prevent intestinal infarction and decrease the risk of bowel segment necrosis. Computed tomographic angiography may be useful for rapid diagnosis. We report recanalization of an SMA occlusion in an 80-year-old man with a combination of intraarterial thrombolysis and mechanical thrombectomy with a carotid filter.

  9. Mechanical Thrombectomy for Early Treatment of Massive Pulmonary Embolism

    SciTech Connect

    Reekers, Jim A. Baarslag, Henk Jan; Koolen, Maria G.J.; Delden, Otto van; Beek, Edwin J.R. van

    2003-06-15

    We report our technique and results of percutaneous mechanical thrombectomy in a consecutive series of eight patients with massive PE. We also discuss the possible role of mechanical PE thrombectomy. Eight consecutive patients with acute massive PE, with or without hemodynamic impairment, were treated with mechanical thrombectomy. We used a modified 7-fr hydrolyzer catheter. The treatment was combined with systemic fibrinolysis. From the logistic and technical point we encountered no problems. All patients showed significant improvement while still in the angiography suite. There were no bleeding complications and no other events related to the procedure. Despite the clinical improvement, one patient died shortly after the procedure from cardiac failure. In all patients there was an acute increase in PO2 to normal values. Only a mean of about 50% of all local thrombus could be removed (range 30-80%). The mean PAP pre-intervention decreased only minimally from 42.5 mmHg to 36.3 mm Hg post-intervention (not significant). In three patients, the PAP continues to remain high at follow-up. The most important feature of mechanical thrombectomy for massive PE is the immediate improvement of the cardiac output, PO2, and clinical situation, overcoming the first critical hours after massive PE. The amount of thrombus reduction seems not to be an important parameter.

  10. Improving Reperfusion Therapies in the Era of Mechanical Thrombectomy

    PubMed Central

    Linfante, Italo; Cipolla, Marilyn J.

    2016-01-01

    Recent positive clinical trials using mechanical thrombectomy proved that endovascular recanalization is an effective treatment for patients with acute stroke secondary to large vessel occlusions. The trials offer definite evidence that in acute ischemia recanalization is a powerful predictor of good outcome. However, even in the era of rapid and effective recanalization using endovascular approaches, the percentage of patients with good outcomes varies between 33% and 71%. In addition, the number of patients who are eligible for endovascular thrombectomy is small and usually based on having salvageable tissue on imaging. There is therefore room for improvement to both enhance the effectiveness of current practice and expand treatment to a larger subset of stroke patients. In this review, we highlight some of the most promising approaches to improve endovascular therapy by combining with strategies to enhance collateral perfusion and vascular protection. PMID:27221511

  11. Mechanical Thrombectomy in Acute Ischemic Stroke: A Systematic Review.

    PubMed

    Lambrinos, Anna; Schaink, Alexis K; Dhalla, Irfan; Krings, Timo; Casaubon, Leanne K; Sikich, Nancy; Lum, Cheemun; Bharatha, Aditya; Pereira, Vitor Mendes; Stotts, Grant; Saposnik, Gustavo; Kelloway, Linda; Xie, Xuanqian; Hill, Michael D

    2016-07-01

    Although intravenous thrombolysis increases the probability of a good functional outcome in carefully selected patients with acute ischemic stroke, a substantial proportion of patients who receive thrombolysis do not have a good outcome. Several recent trials of mechanical thrombectomy appear to indicate that this treatment may be superior to thrombolysis. We therefore conducted a systematic review and meta-analysis to evaluate the clinical effectiveness and safety of new-generation mechanical thrombectomy devices with intravenous thrombolysis (if eligible) compared with intravenous thrombolysis (if eligible) in patients with acute ischemic stroke caused by a proximal intracranial occlusion. We systematically searched seven databases for randomized controlled trials published between January 2005 and March 2015 comparing stent retrievers or thromboaspiration devices with best medical therapy (with or without intravenous thrombolysis) in adults with acute ischemic stroke. We assessed risk of bias and overall quality of the included trials. We combined the data using a fixed or random effects meta-analysis, where appropriate. We identified 1579 studies; of these, we evaluated 122 full-text papers and included five randomized control trials (n=1287). Compared with patients treated medically, patients who received mechanical thrombectomy were more likely to be functionally independent as measured by a modified Rankin score of 0-2 (odds ratio, 2.39; 95% confidence interval, 1.88-3.04; I2=0%). This finding was robust to subgroup analysis. Mortality and symptomatic intracerebral hemorrhage were not significantly different between the two groups. Mechanical thrombectomy significantly improves functional independence in appropriately selected patients with acute ischemic stroke.

  12. Stent-based mechanical thrombectomy in acute basilar artery occlusion.

    PubMed

    Cohen, José E; Leker, Ronen R; Moscovici, Samuel; Attia, Moshe; Itshayek, Eyal

    2011-12-01

    Stent-based mechanical thrombectomy was recently proposed as an effective alternative to other mechanical techniques to achieve recanalization of large-vessel embolic occlusions in the anterior circulation. To our knowledge, there are no reports of the use of this technique in acute basilar artery occlusion (ABAO). We present a patient with complete endovascular recanalization of ABAO using a stent-based thrombectomy technique. Advantages and limitations of this technique in the management of ABAO are discussed. The stent-thrombectomy technique is promising, and will need further evaluation in posterior circulation stroke. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Superior Mesenteric Artery Embolism Treated with Percutaneous Mechanical Thrombectomy

    SciTech Connect

    Popovic, Peter Kuhelj, Dimitrij; Bunc, Matjaz

    2011-02-15

    A case of acute superior mesenteric artery embolism treated with percutaneous thrombus aspiration is described. A 63-year-old man with chronic atrial fibrillation was admitted to the hospital with progressive abdominal pain. Computed tomography angiography revealed an occlusion of the distal part of the superior mesenteric artery. The patient was effectively treated using transaxillary percutaneous mechanical thrombectomy using a 6F Aspirex thrombectomy catheter.

  14. Influence of Thrombus Age on the Mechanical Thrombectomy Efficacy of the Amplatz Thrombectomy Device In Vitro

    SciTech Connect

    Grimm, Jan Jahnke, Thomas; Muhle, Claus; Heller, Martin; Mueller-Huelsbeck, Stefan

    2003-06-15

    Purpose: To determine the efficacy of thrombectomy for the Amplatz Thrombectomy Device (ATD) according to the age of the thrombus. Methods: Thrombectomy was performed with the 7 Fr or 8 Fr ATD. Five-day-old or 8-day-old thrombi were made from porcine blood by clotting within silicone tubes to be used in a flow model. Emboli sizes, weight, remaining thrombus and activation time were evaluated. Results: The age of the thrombus had no influence on the activation time necessary for complete thrombolysis. A significant difference was found in the overall amount of embolization only with the 7 Fr device although a similar trend was shown with the 8 Fr device. The amount of embolized thrombotic material was higher for both devices if older thrombi (i.e., 8 days old) we reprocessed. The overall impression was that the 8 Fr device showed slightly better results (less remaining thrombus and embolization). Conclusion: A tendency toward higher amounts of embolization was observed if older thrombi were used in the model. Therefore the interventional radiologist should be aware of the potentially higher risk of peripheral embolization when performing mechanical thrombectomy(with the ATD) in older thrombotic occlusions, especially since the higher rate of embolization was mainly due to an increased proportion of larger embolic particles (1 mm), which are clinically more significant.

  15. Mechanical Thrombectomy of Occluded Hemodialysis Native Fistulas and Grafts Using a Hydrodynamic Thrombectomy Catheter: Preliminary Experience

    SciTech Connect

    Sahni, Vikram Kaniyur, Sunil; Malhotra, Anmol; Fan, Stanley; Blakeney, Charles; Fotheringham, Tim; Sobeh, Mohammed; Matson, Matthew

    2005-12-15

    The purpose of this study was to evaluate the efficacy and safety of a new hydrodynamic percutaneous thrombectomy catheter in the treatment of thrombosed hemodialysis fistulas and grafts. Twenty-two patients (median age: 47 years; range: 31-79 years) underwent mechanical thrombectomy for thrombosed hemodialysis fistulas or polytetrafluoroethylene (PTFE) grafts. In all cases, an Oasis hydrodynamic catheter was used. Five patients had native fistulas and 17 had PTFE grafts. Six patients required repeat procedures. All patients with native fistulas and 15 of the 17 with PTFE grafts also underwent angioplasty of the venous limb following the thrombectomy. Major outcome measures included technical success, clinical success, primary and secondary patency, and complication rates. Twenty-eight procedures were performed in total. The technical success rate was 100% and 90% and clinical success was 86% and 76% for native fistulas and grafts, respectively. The primary patency at 6 months was 50% and 59% for fistulas and grafts, respectively, and the secondary patency at 6 months was 75% and 70% for fistulas and grafts, respectively. Two patients died of unrelated causes during the follow-up period. The Oasis catheter is an effective mechanical device for the percutaneous treatment of thrombosed hemodialysis access. Our initial success rate showed that the technique is safe in the treatment of both native fistulas and grafts.

  16. A Novel Mechanical Thrombectomy Device for Retrieval of Intravascular Thrombus

    SciTech Connect

    Monsky, Wayne L.; Finitsis, Stephanos; Cicco, Dino De; Brock, John M.; Kucharczyk, John; Latchaw, Richard E.

    2011-04-15

    Purpose: Thrombotic and embolic vascular occlusion represents a leading cause of morbidity and mortality. Currently available thrombectomy devices have limitations, including difficulty removing organized thrombus and clot fragmentation with distal embolization. A novel mechanical thrombectomy device (MTD), designed to remove both hard and soft thrombus without trauma to the blood vessel, was tested in preclinical porcine models evaluating efficacy, safety, and ease of use. Materials and Methods: A total of 26 vessels in 14 pigs underwent mechanical thrombectomy with MTD. Thrombectomy was performed in nine superficial femoral arteries, eight subclavian arteries, five primary branches of the subclavian artery, lateral thoracic artery or the thyrocervical trunk, and four external carotids. Subacute organized fibrin-laden thrombus was injected into the arteries producing vascular occlusion. The MTD was then used for thrombectomy to restore patency and blood flow. Results: Intact thrombus was retrieved from 24 of 26 of the vessels with a single pass of the MTD, resulting in complete restoration of patency in 21 vessels and partial patency in 4 vessels. In 8 cases that used an early design, the embolic material fragmented during withdrawal from the access sheath. In 4 procedures that used an early design, the MTD failed to deploy fully and the embolus was not completely captured. No intraprocedural complications or vascular damage occurred. Conclusions: The present pilot studies demonstrate basic safety and efficacy of a novel MTD with design attributes suitable for retrieval of intact acute and organized chronic thrombus. The device has potential intracranial and peripheral utility.

  17. Mechanical Solitaire Thrombectomy with Low-Dose Booster Tirofiban Injection.

    PubMed

    Goh, Duck-Ho; Jin, Sung-Chul; Jeong, Hae Woong; Ha, Sam Yeol

    2016-09-01

    Mechanical thrombectomy using a Solitaire stent has been associated with a high recanalization rate and favorable clinical outcome in intra-arterial thrombolysis. To achieve a higher recanalization rate for mechanical Solitaire thrombectomy, we used an intra-arterial low-dose booster tirofiban injection into the occluded segment after stent deployment. We report the safety and recanalization rates for mechanical Solitaire thrombectomy with a low-dose booster tirofiban injection. Between February and March 2013, 13 consecutive patients underwent mechanical Solitaire thrombectomy with low-dose booster tirofiban injection. The occlusion sites included the proximal middle cerebral artery (5 patients), the internal carotid artery (5 patients), the top of the basilar artery (2 patients) and the distal middle cerebral artery (M2 segment, 1 patient). Six patients underwent bridge treatment, including intravenous tissue plasminogen activator. Tirofiban of 250 µg was used in all patients except one (500 µg). All occluded vessels were recanalized after 3 attempts at stent retrieval (1 time, n=9; 2 times, n=2; 3 times, n=2). Successful recanalization was achieved in all patients (TICI 3, n=8; TICI 2b, n=5). Procedural complications developed in 3 patients (subarachnoid hemorrhage, n=2; hemorrhagic transformation, n=1). Mortality occurred in one patient with a basilar artery occlusion due to reperfusion brain swelling after mechanical Solitaire thrombectomy with low-dose booster tirofiban injection. Favorable clinical outcome (mRS≤2) was observed in 8 patients (61.5%). Our modified mechanical Solitaire thrombectomy method using a low-dose booster tirofiban injection might enhance the recanalization rate with no additive hemorrhagic complications.

  18. Mechanical Solitaire Thrombectomy with Low-Dose Booster Tirofiban Injection

    PubMed Central

    Goh, Duck-Ho; Jeong, Hae Woong; Ha, Sam Yeol

    2016-01-01

    Purpose Mechanical thrombectomy using a Solitaire stent has been associated with a high recanalization rate and favorable clinical outcome in intra-arterial thrombolysis. To achieve a higher recanalization rate for mechanical Solitaire thrombectomy, we used an intra-arterial low-dose booster tirofiban injection into the occluded segment after stent deployment. We report the safety and recanalization rates for mechanical Solitaire thrombectomy with a low-dose booster tirofiban injection. Materials and Methods Between February and March 2013, 13 consecutive patients underwent mechanical Solitaire thrombectomy with low-dose booster tirofiban injection. The occlusion sites included the proximal middle cerebral artery (5 patients), the internal carotid artery (5 patients), the top of the basilar artery (2 patients) and the distal middle cerebral artery (M2 segment, 1 patient). Six patients underwent bridge treatment, including intravenous tissue plasminogen activator. Tirofiban of 250 µg was used in all patients except one (500 µg). All occluded vessels were recanalized after 3 attempts at stent retrieval (1 time, n=9; 2 times, n=2; 3 times, n=2). Results Successful recanalization was achieved in all patients (TICI 3, n=8; TICI 2b, n=5). Procedural complications developed in 3 patients (subarachnoid hemorrhage, n=2; hemorrhagic transformation, n=1). Mortality occurred in one patient with a basilar artery occlusion due to reperfusion brain swelling after mechanical Solitaire thrombectomy with low-dose booster tirofiban injection. Favorable clinical outcome (mRS≤2) was observed in 8 patients (61.5%). Conclusion Our modified mechanical Solitaire thrombectomy method using a low-dose booster tirofiban injection might enhance the recanalization rate with no additive hemorrhagic complications. PMID:27621948

  19. Mechanical thrombectomy for acute ischemic stroke with cerebral microbleeds.

    PubMed

    Shi, Zhong-Song; Duckwiler, Gary R; Jahan, Reza; Tateshima, Satoshi; Gonzalez, Nestor R; Szeder, Viktor; Saver, Jeffrey L; Kim, Doojin; Ali, Latisha K; Starkman, Sidney; Vespa, Paul M; Salamon, Noriko; Villablanca, J Pablo; Viñuela, Fernando; Feng, Lei; Loh, Yince; Liebeskind, David S

    2016-06-01

    The influence of cerebral microbleeds (CMBs) on post-thrombolytic hemorrhagic transformation (HT) in patients with acute ischemic stroke remains controversial. To investigate the association of CMBs with HT and clinical outcomes among patients with large-vessel occlusion strokes treated with mechanical thrombectomy. We analyzed patients with acute stroke treated with Merci Retriever, Penumbra system or stent-retriever devices. CMBs were identified on pretreatment T2-weighted, gradient-recall echo MRI. We analyzed the association of the presence, burden, and distribution of CMBs with HT, procedural complications, in-hospital mortality, and clinical outcome. CMBs were detected in 37 (18.0%) of 206 patients. Seventy-three foci of microbleeds were identified. Fourteen patients (6.8%) had ≥2 CMBs, only 1 patient had ≥5 CMBs. Strictly lobar CMBs were found in 12 patients, strictly deep CMBs in 12 patients, strictly infratentorial CMBs in 2 patients, and mixed CMBs in 11 patients. There were no significant differences between patients with CMBs and those without CMBs in the rates of overall HT (37.8% vs 45.6%), parenchymal hematoma (16.2% vs 19.5%), procedure-related vessel perforation (5.4% vs 7.1%), in-hospital mortality (16.2% vs 18.3%), and modified Rankin Scale score 0-3 at discharge. CMBs were not independently associated with HT or in-hospital mortality in patients treated with either thrombectomy or intravenous thrombolysis followed by thrombectomy. Patients with CMBs are not at increased risk for HT and mortality following mechanical thrombectomy for acute stroke. Excluding such patients from mechanical thrombectomy is unwarranted. The risk of HT in patients with ≥5 CMBs requires further study. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  20. Percutaneous mechanical thrombectomy for treatment of acute femoropopliteal bypass occlusion.

    PubMed

    Lichtenberg, Michael; Käunicke, Matthias; Hailer, Birgit

    2012-01-01

    Acute and subacute ischemia of the legs in acute and subacute femoropopliteal bypass occlusion is a dramatic situation that endangers the survival of the limbs, depending on the severity of the ischemia. Different therapy options like percutaneous mechanical thrombectomy procedures, which include rotational thrombectomy, have become available in recent years, in addition to local lysis and surgical thrombectomy. Surgical thrombectomy using the Fogarty catheter technique, in particular, shows an increased incidence of perioperative complications but only small technical success rates in randomized trials. On the other hand, local lysis is associated with increased costs due to resource-consuming measures, such as intensive monitoring and repeat angiographies, in addition to bleeding complications. In the past, further development of the Straub Rotarex(®) system as an endovascular therapy option has demonstrated good success leading to amputation-free survival in multiple studies. At the same time, a low rate of complications with use has been documented. Most examinations have been conducted in the thigh. To date, there are little investigational data on its use in acutely and subacutely occluded femoropopliteal bypasses. In this paper, the current study-based significance of the Rotarex system for this indication is analyzed based on the existing literature and the authors' own experiences with 22 patients.

  1. Percutaneous mechanical thrombectomy for treatment of acute femoropopliteal bypass occlusion

    PubMed Central

    Lichtenberg, Michael; Käunicke, Matthias; Hailer, Birgit

    2012-01-01

    Acute and subacute ischemia of the legs in acute and subacute femoropopliteal bypass occlusion is a dramatic situation that endangers the survival of the limbs, depending on the severity of the ischemia. Different therapy options like percutaneous mechanical thrombectomy procedures, which include rotational thrombectomy, have become available in recent years, in addition to local lysis and surgical thrombectomy. Surgical thrombectomy using the Fogarty catheter technique, in particular, shows an increased incidence of perioperative complications but only small technical success rates in randomized trials. On the other hand, local lysis is associated with increased costs due to resource-consuming measures, such as intensive monitoring and repeat angiographies, in addition to bleeding complications. In the past, further development of the Straub Rotarex® system as an endovascular therapy option has demonstrated good success leading to amputation-free survival in multiple studies. At the same time, a low rate of complications with use has been documented. Most examinations have been conducted in the thigh. To date, there are little investigational data on its use in acutely and subacutely occluded femoropopliteal bypasses. In this paper, the current study-based significance of the Rotarex system for this indication is analyzed based on the existing literature and the authors’ own experiences with 22 patients. PMID:22661895

  2. Mechanical Thrombectomy in Patients with Deep Venous Thrombosis

    SciTech Connect

    Delomez, Maxence; Beregi, Jean-Paul; Willoteaux, Serge; Bauchart, Jean-Jacques; D'Othee, Bertrand Janne; Asseman, Philippe; Perez, Nessim; Thery, Claude

    2001-01-15

    Purpose: To report our experience with mechanical thrombectomy in proximal deep vein thrombosis (DVT).Methods: Eighteen patients with a mean ({+-} SD) age of 37.6 {+-} 16.1 years who presented with DVT in the iliac and femoral vein (n = 3), inferior vena cava (n = 5), or inferior vena cava and iliac vein (n = 10), were treated with the Amplatz Thrombectomy Device after insertion of a temporary caval filter.Results: Successful recanalization was achieved in 15 of 18 patients (83%). Overall, the percentage of thrombus removed was 66 {+-} 29%: 73 {+-} 30% at caval level and 55 {+-} 36% at iliofemoral level. Complementary interventions (seven patients) were balloon angioplasty (n = 2), angioplasty and stenting (n = 2), thrombo-aspiration alone (n = 1), thrombo-aspiration, balloon angioplasty, and permanent filter (n = 1), and permanent filter alone (n = 1). There was one in-hospital death. Follow-up was obtained at a mean of 29.6 months; three patients had died (two cancers, one myocardial infarction); 10 had no or minimal sequelae; one had post-phlebitic limb.Conclusion: Mechanical thrombectomy is a potential therapeutic option in patients presenting with proximal DVT.

  3. Aspiration thrombectomy in concert with stent thrombectomy.

    PubMed

    Dumont, Travis M; Mokin, Maxim; Sorkin, Grant C; Levy, Elad I; Siddiqui, Adnan H

    2013-07-12

    In the SWIFT and TREVO 2 trials, aspiration thrombectomy was not able to be performed. Outside these studies, in post-market application, the interventionist can use aspiration thrombectomy in addition to stent device thrombectomy. This technique is described in detail in the present report. Combined aspiration/stentriever thrombectomy may improve recanalization efforts, simplify a second thrombectomy attempt if necessary and may limit distal embolization.

  4. Evolution of endovascular mechanical thrombectomy for acute ischemic stroke

    PubMed Central

    Przybylowski, Colin J; Ding, Dale; Starke, Robert M; Durst, Christopher R; Crowley, R Webster; Liu, Kenneth C

    2014-01-01

    Acute ischemic stroke (AIS) is a common medical problem associated with significant morbidity and mortality worldwide. A small proportion of AIS patients meet eligibility criteria for intravenous thrombolysis (IVT) with recombinant tissue plasminogen activator, and its efficacy for large vessel occlusion is poor. Therefore, an increasing number of patients with AIS are being treated with endovascular mechanical thrombectomy when IVT is ineffective or contraindicated. Rapid advancement in catheter-based and endovascular device technology has led to significant improvements in rates of cerebral reperfusion with these devices. Stentrievers and modern aspiration catheters have now surpassed earlier generation devices in the degree and rapidity of revascularization. This progress has been achieved with no concurrent increase in risk of major complications or mortality, both when used alone or in combination with IVT. The initial randomized controlled trials comparing endovascular therapy to IVT for AIS failed to show superior outcomes with endovascular treatment, but key limitations of each trial may limit the significance of these results to current practice. While endovascular devices and operator experience continue to evolve, we are optimistic that this will be accompanied by improvements in patient outcomes. This review highlights the major endovascular devices used in current practice and the trials which have investigated their efficacy. PMID:25405185

  5. Evolution of endovascular mechanical thrombectomy for acute ischemic stroke.

    PubMed

    Przybylowski, Colin J; Ding, Dale; Starke, Robert M; Durst, Christopher R; Crowley, R Webster; Liu, Kenneth C

    2014-11-16

    Acute ischemic stroke (AIS) is a common medical problem associated with significant morbidity and mortality worldwide. A small proportion of AIS patients meet eligibility criteria for intravenous thrombolysis (IVT) with recombinant tissue plasminogen activator, and its efficacy for large vessel occlusion is poor. Therefore, an increasing number of patients with AIS are being treated with endovascular mechanical thrombectomy when IVT is ineffective or contraindicated. Rapid advancement in catheter-based and endovascular device technology has led to significant improvements in rates of cerebral reperfusion with these devices. Stentrievers and modern aspiration catheters have now surpassed earlier generation devices in the degree and rapidity of revascularization. This progress has been achieved with no concurrent increase in risk of major complications or mortality, both when used alone or in combination with IVT. The initial randomized controlled trials comparing endovascular therapy to IVT for AIS failed to show superior outcomes with endovascular treatment, but key limitations of each trial may limit the significance of these results to current practice. While endovascular devices and operator experience continue to evolve, we are optimistic that this will be accompanied by improvements in patient outcomes. This review highlights the major endovascular devices used in current practice and the trials which have investigated their efficacy.

  6. New Cerebral Microbleeds After Mechanical Thrombectomy for Large-Vessel Occlusion Strokes.

    PubMed

    Shi, Zhong-Song; Duckwiler, Gary R; Jahan, Reza; Tateshima, Satoshi; Gonzalez, Nestor R; Szeder, Viktor; Saver, Jeffrey L; Kim, Doojin; Ali, Latisha K; Starkman, Sidney; Vespa, Paul M; Salamon, Noriko; Villablanca, J Pablo; Viñuela, Fernando; Feng, Lei; Loh, Yince; Liebeskind, David S

    2015-11-01

    The interval appearance of cerebral microbleeds (CMBs) after endovascular treatment has never been described. We investigated the frequency and predictors of new CMBs that developed shortly after mechanical thrombectomy for acute ischemic stroke, and its impact on clinical outcome.We retrospectively analyzed patients with large-vessel occlusion strokes treated with Merci Retriever, Penumbra System, or stent-retriever devices. Serial T2*-weighted gradient-recall echo (GRE) magnetic resonance imaging (MRI) before and 48 h after endovascular thrombectomy were assessed to identify new CMBs. We examined independent factors associated with new CMBs after mechanical thrombectomy. We analyzed the association of the presence, burden, and distribution of new CMBs with clinical outcome.A total of 187 consecutive patients with serial GRE were enrolled in this study. CMBs were evident in 36 (19.3%) patients before mechanical thrombectomy. New CMBs occurred in 41 (21.9%) patients after mechanical thrombectomy. Of the 68 new CMBs, 45 appeared in the lobar location, 18 in the deep location and 5 in the infratentorial location. The presence of baseline CMBs was associated with new CMBs after mechanical thrombectomy (OR 5.38; 95% CI 2.13-13.59; P < 0.001), no matter whether the patients were treated primarily with mechanical thrombectomy or with intravenous thrombolysis followed by mechanical thrombectomy. Patients with new CMBs did not have increased rates of hemorrhagic transformation, in-hospital mortality, and modified Rankin Scale score 4 to 6 at discharge.New CMBs are common after mechanical thrombectomy in one-fifth of patients with acute ischemic stroke. Baseline CMBs before mechanical thrombectomy predicts the development of new CMBs. New CMBs after mechanical thrombectomy do not influence clinical outcome.

  7. New Cerebral Microbleeds After Mechanical Thrombectomy for Large-Vessel Occlusion Strokes

    PubMed Central

    Shi, Zhong-Song; Duckwiler, Gary R.; Jahan, Reza; Tateshima, Satoshi; Gonzalez, Nestor R.; Szeder, Viktor; Saver, Jeffrey L.; Kim, Doojin; Ali, Latisha K.; Starkman, Sidney; Vespa, Paul M.; Salamon, Noriko; Villablanca, J. Pablo; Viñuela, Fernando; Feng, Lei; Loh, Yince; Liebeskind, David S.

    2015-01-01

    Abstract The interval appearance of cerebral microbleeds (CMBs) after endovascular treatment has never been described. We investigated the frequency and predictors of new CMBs that developed shortly after mechanical thrombectomy for acute ischemic stroke, and its impact on clinical outcome. We retrospectively analyzed patients with large-vessel occlusion strokes treated with Merci Retriever, Penumbra System, or stent-retriever devices. Serial T2∗-weighted gradient-recall echo (GRE) magnetic resonance imaging (MRI) before and 48 h after endovascular thrombectomy were assessed to identify new CMBs. We examined independent factors associated with new CMBs after mechanical thrombectomy. We analyzed the association of the presence, burden, and distribution of new CMBs with clinical outcome. A total of 187 consecutive patients with serial GRE were enrolled in this study. CMBs were evident in 36 (19.3%) patients before mechanical thrombectomy. New CMBs occurred in 41 (21.9%) patients after mechanical thrombectomy. Of the 68 new CMBs, 45 appeared in the lobar location, 18 in the deep location and 5 in the infratentorial location. The presence of baseline CMBs was associated with new CMBs after mechanical thrombectomy (OR 5.38; 95% CI 2.13–13.59; P < 0.001), no matter whether the patients were treated primarily with mechanical thrombectomy or with intravenous thrombolysis followed by mechanical thrombectomy. Patients with new CMBs did not have increased rates of hemorrhagic transformation, in-hospital mortality, and modified Rankin Scale score 4 to 6 at discharge. New CMBs are common after mechanical thrombectomy in one-fifth of patients with acute ischemic stroke. Baseline CMBs before mechanical thrombectomy predicts the development of new CMBs. New CMBs after mechanical thrombectomy do not influence clinical outcome. PMID:26632753

  8. Mechanical Thrombectomy with Rotarex System in Buerger's Disease.

    PubMed

    Kilickesmez, Ozgur; Oguzkurt, Levent

    2015-01-01

    We report the case of a patient with 2-month history of chronic thromboembolism of the distal superficial femoral and popliteal arteries with diagnostic features of thromboangiitis obliterans disease. The occlusion could not be crossed by antegrade approach and was achieved retrogradely via dorsalis pedis artery puncture followed by mechanical removal of the thrombus with Rotarex system (Straub Medical AG, Wangs, Switzerland). Subsequent ballooon angioplasties achieved exclusion of the thrombus, and straight-line flow established to the foot through the anterior tibial Artery. The present case report demonstrates the success of mechanical thrombectomy in a patient with Buerger's vasculitis.

  9. Mechanical Thrombectomy with Rotarex System in Buerger's Disease

    PubMed Central

    Kilickesmez, Ozgur; Oguzkurt, Levent

    2015-01-01

    We report the case of a patient with 2-month history of chronic thromboembolism of the distal superficial femoral and popliteal arteries with diagnostic features of thromboangiitis obliterans disease. The occlusion could not be crossed by antegrade approach and was achieved retrogradely via dorsalis pedis artery puncture followed by mechanical removal of the thrombus with Rotarex system (Straub Medical AG, Wangs, Switzerland). Subsequent ballooon angioplasties achieved exclusion of the thrombus, and straight-line flow established to the foot through the anterior tibial Artery. The present case report demonstrates the success of mechanical thrombectomy in a patient with Buerger's vasculitis. PMID:25861548

  10. Comparison of a Balloon Guide Catheter and a Non-Balloon Guide Catheter for Mechanical Thrombectomy.

    PubMed

    Velasco, Aglaé; Buerke, Boris; Stracke, Christian P; Berkemeyer, Shoma; Mosimann, Pascal J; Schwindt, Wolfram; Alcázar, Pedro; Cnyrim, Christian; Niederstadt, Thomas; Chapot, René; Heindel, Walter

    2016-07-01

    Purpose To evaluate the effectiveness of mechanical thrombectomy with the use of a stent retriever in acute ischemic stroke, performed by using a balloon guide catheter or non-balloon guide catheter. Materials and Methods In accordance with the institutional review board approval obtained at the two participating institutions, retrospective analysis was performed in 183 consecutive patients treated between 2013 and 2014 for occlusions in the middle cerebral artery or carotid terminus by using a stent retriever with a balloon guide catheter (n = 102) at one center and a non-balloon guide catheter (n = 81) at the other center. Data on procedure duration, number of passes, angiographic findings, type of stent retriever used, and expertise of the operators were collected. Successful recanalization was defined as grade 3 or 2b modified Treatment in Cerebral Ischemia recanalization accomplished in up to three passes. Univariate and multivariate subgroup analyses were conducted to control for the confounding variables of prior thrombolysis, location of occlusion, and operator expertise. Results Successful recanalization with the balloon guide catheter was achieved in 89.2% of thrombectomies (91 of 102) versus 67.9% (55 of 81) achieved with the non-balloon guide catheter (P = .0004). The one-pass thrombectomy rate with the balloon guide catheter was significantly higher than for that with the non-balloon guide catheter (63.7% [65 of 102] vs 35.8% [29 of 81], respectively; P = .001). The procedure duration was significantly shorter by using the balloon guide catheter than the non-balloon guide catheter (median, 20.5 minutes vs 41.0 minutes, respectively; P < .0001). Conclusion The effectiveness of mechanical thrombectomy with stent retrievers in acute ischemic stroke in the anterior circulation in terms of angiographic results and procedure duration was improved when performed in combination with the balloon guide catheter. (©) RSNA, 2016.

  11. Mechanical thrombectomy in pediatric acute ischemic stroke: Clinical outcomes and literature review.

    PubMed

    Madaelil, Thomas P; Kansagra, Akash P; Cross, DeWitte T; Moran, Christopher J; Derdeyn, Colin P

    2016-08-01

    There are limited data on outcomes of mechanical thrombectomy for pediatric stroke using modern devices. In this study, we report two cases of pediatric acute ischemic stroke treated with mechanical thrombectomy, both with good angiographic result (TICI 3) and clinical outcome (no neurological deficits at 90 days). In addition, we conducted a literature review of all previously reported cases describing the use of modern thrombectomy devices. Including our two cases, the aggregate rate of partial or complete vessel recanalization was 100% (22/22), and the aggregate rate of favorable clinical outcome was 91% (20/22). This preliminary evidence suggests that mechanical thrombectomy with modern devices may be a safe and effective treatment option in pediatric patients with acute ischemic stroke. © The Author(s) 2016.

  12. Massive intravascular hemolysis with mechanical rheolytic thrombectomy of a hemodialysis arteriovenous fistula.

    PubMed

    Carrera, Louis A; Reddy, Rachita; Pamoukian, Vicken N; Michelis, Michael F; DeVita, Maria V; Rosenstock, Jordan

    2013-01-01

    A 57-year-old man with chronic kidney disease stage 5 presented for ambulatory evaluation of his arteriovenous fistula. He underwent rheolytic thrombectomy with tissue plasminogen activator infusion, angioplasty, and brachial artery stenting under local sedation. His immediate postoperative course was complicated by hypotension, cardiac dysrhythmias and hyperkalemia requiring emergent hemodialysis, due to severe intravascular hemolysis. This case illustrates that mechanical thrombectomy can cause clinically significant intravascular hemolysis, thus careful postoperative monitoring is recommended.

  13. The blower: a useful tool to complete thrombectomy of the mechanical prosthetic valve.

    PubMed

    Aroussi, Aziz Alami; Sami, Ibrahim Mohamed; Leguerrier, Alain; Verhoye, Jean Phillippe

    2006-05-01

    Thrombectomy could be an excellent approach on one condition (ie, that all parts of the thrombus are removed). We propose to use a tool (ie, the blower) to complete thrombectomy of the prosthetic mechanical valve. The blower is a vaporizer that mixes air and heparinized saline with regulator of flow and proportion used in beating heart surgery. For thrombectomy, we have modified the air-water mixing part and intensity until we obtained a jet that enabled us to remove the micro thrombus that covered the prosthetic valve and surrounding tissues. The blower completely cleaned the prosthetic valve. With this tool, thrombectomy seems easier, more complete, and more reliable with the advantages of short cross-clamping time.

  14. Percutaneous mechanical thrombectomy of superior mesenteric artery embolism

    PubMed Central

    Kuhelj, Dimitrij; Kavcic, Pavel; Popovic, Peter

    2013-01-01

    Background The present series present three consecutive cases of successful percutaneous mechanical embolectomy in acute superior mesenteric artery ischemia. Superior mesenteric artery embolism is a rare abdominal emergency that commonly leads to bowel infarction and has a very high mortality rate. Prompt recognition and treatment are crucial for successful outcome. Endovascular therapeutic approach in patients with acute SMA embolism in median portion of its stem is proposed. Case reports. Three male patients had experienced a sudden abdominal pain and acute superior mesenteric artery embolism in median portion of its stem was revealed on computed tomography angiography. No signs of intestinal infarction were present. The decision for endovascular treatment was made in concordance with the surgeons. In one patient 6 French gauge Rotarex® device was used while in others 6 French gauge Aspirex® device were used. All patients experienced sudden relief of pain after the procedure with no signs of intestinal infarction. Minor procedural complication – rupture of a smaller branch of SMA during Aspirex® treatment was successfully managed by coiling while transient paralytic ileus presented in one patient resolved spontaneously. All three patients remained symptom-free with patent superior mesenteric artery during the follow-up period. Conclusions Percutaneous mechanical thrombectomy seems to be a rapid and effective treatment of acute superior mesenteric artery embolism in median portion of its stem in absence of bowel necrosis. Follow-up of our patients showed excellent short- and long-term results. PMID:24133388

  15. Primary stentriever versus combined stentriever plus aspiration thrombectomy approaches: in vitro stroke model comparison

    PubMed Central

    Mokin, Maxim; Ionita, Ciprian N; Nagesh, Swetadri Vasan Setlur; Rudin, Stephen; Levy, Elad I; Siddiqui, Adnan H

    2014-01-01

    Background Artificial stroke models can be used for testing various thrombectomy devices. Objective To determine the value of combined stentriever–aspiration thrombectomy compared with the stentriever-alone approach. Methods We designed an in vitro model of the intracranial circulation with a focus on the middle cerebral artery (MCA) that closely resembles the human intracranial circulation. After introducing fresh clot in the MCA, we used conventional biplane angiography and microangiographic fluoroscopy to compare recanalization rates and occurrence of emboli in new, unaffected territory for thrombectomy approaches in which a stentriever (Solitaire flow restoration stentriever, Covidien) was used alone or in combination with continuous manual aspiration through a Navien catheter (Covidien). Results In a total of 22 experiments (11 for each approach), successful clot delivery to the MCA was achieved in all cases. Successful angiographic recanalization (thrombolysis in cerebral infarction score of 2b–3) was achieved more frequently with the combined stentriever–aspiration approach than with the stentriever-alone approach (in 10 vs 4 experiments, p=0.023). Emboli in new territory occurred in three experiments with the stentriever-alone approach, and none were seen with the combined approach (p=0.21). Conclusions The combined stentriever–aspiration approach to thrombectomy leads to better angiographic recanalization rates than use of the stentriever alone. Further experiments are needed to test the value of balloon-guide catheters and aspiration performed using other types of catheters and modes of aspiration. PMID:24789594

  16. Mechanical thrombectomy for acute stroke in childhood: how much does restricted diffusion matter?

    PubMed

    Ladner, Travis R; He, Lucy; Jordan, Lori C; Cooper, Calvin; Froehler, Michael T; Mocco, J

    2015-12-01

    Mechanical thrombectomy holds promise for children with large cerebral arterial occlusions, although there are few reports in this population. We report a case of retrievable stent-assisted mechanical thrombectomy in a 5-year-old with basilar artery occlusion, despite late presentation and extensive initial diffusion-weighted imaging (DWI) restriction. This resulted in successful Thrombolysis in Cerebral Infarction 2B reperfusion and excellent clinical outcome. At 6-week follow-up he was completely back to baseline with no residual deficits (pediatric stroke outcome measure=0, modified Rankin scale=0). At 3-month follow-up the patient has not had any recurrent stroke or concern for stroke-like symptoms. We review the literature on mechanical thrombectomy and DWI changes in acute stroke in early to middle childhood (<12 years old).

  17. [Mechanical thrombectomy in the treatment of acute disturbance of cerebral circulation].

    PubMed

    Pienimäki, Juha-Pekka; Ollikainen, Jyrki; Kähärä, Veikko; Seppänen, Janne; Numminen, Heikki

    2013-01-01

    An essential aim of acute treatment of brain infarction is to restrict the size of the infarct by rapid and permanent recanalization of the obstructed artery. Thrombolytic therapy based on intravenous administration of alteplas (IV-tPA) exhibits the highest efficacy in the treatment of cerebral artery thrombi that are fairly small or intermediate in size. Intra-arterial thrombolysis (IA-tPA) and mechanical thrombectomy can be considered, if IV-tPA turns out to be ineffective or is contraindicated. In situations where the expected effect of IV-tPA:n is modest per se, mechanical thrombectomy should be taken into account as part of the therapeutic strategy.

  18. Simple mechanical thrombectomy with intrapulmonary arterial thrombolysis in pulmonary thromboembolism: a small case series

    PubMed Central

    Ahmed, Khurshid; Munawar, Muhammad; Andina Munawar, Dian; Hartono, Beny

    2014-01-01

    Pulmonary thromboembolism (PTE) is a life-threatening condition with a high early mortality rate caused by acute right ventricular failure and cardiogenic shock. We report a series of three patients who presented with acute and subacute submassive PTE. They were successfully treated by simple catheter-based mechanical thrombectomy and intrapulmonary arterial thrombolysis. Mechanical fragmentation and aspiration of thrombus was performed by commonly used J-wire, multi-purpose and Judkin Right guiding catheters and this obviated the need of specific thrombectomy devices. PMID:25593584

  19. Basilar artery occlusion in a child treated successfully with mechanical thrombectomy using ADAPT.

    PubMed

    Lena, Jonathan; Eskandari, Ramin; Infinger, Libby; Fargen, Kyle M; Spiotta, Alejandro; Turk, Aquilla; Turner, Raymond D; Chaudry, Imran

    2016-04-11

    Acute ischemic stroke (AIS) in the pediatric population is rare. Furthermore, it is common for physicians to take significantly longer diagnosing a posterior circulation stroke in a child than in an adult. There are increasing case reports in the literature of treating AIS in children with intravenous tissue plasminogen activator, intra-arterial thrombolysis, and/or mechanical thrombectomy. We present the first case of pediatric AIS treated using a direct aspiration first pass technique (ADAPT) as a means of mechanical thrombectomy. 2016 BMJ Publishing Group Ltd.

  20. Advantages to Indigo mechanical thrombectomy for ALI: device and technique.

    PubMed

    Yamada, R; Adams, J; Guimaraes, M; Schönholz, C

    2015-06-01

    Catheter-directed thrombolysis (CDT) has been used as the first therapeutic option for acute limb ischemia (ALI) due to its less invasive nature; however, recent systematic review showed higher incidence of major complications related to lytic infusion, including hemorrhagic stroke. In this setting, aspiration thrombectomy with Indigo has the greatest advantage of not increasing systemic risk of bleeding. The Indigo™ system from Penumbra® (Alameda, CA, USA) promotes active thrombectomy using a vacuum pump that generates substantial suction, enabling aspiration of clots of varying sizes and lengths. The device has three components: aspiration catheter, separator and pump. There are 2 aspiration catheter sizes: CAT 3 and CAT 5. The separators are intended to mobilize the clot and clean the catheter lumen, and therefore restoring flow for continuous aspiration. The pump is small-sized equipment capable of applying near pure vacuum aspiration pressure of -29 mmHg. Aspiration thrombectomy with Indigo has two key advantages: it does not require the use of lytics, and it provides immediate flow reestablishment. Its use when thrombolysis is contraindicated or has failed is already well established and, in the future, it may likely become the first line endovascular option in patients with acute limb ischemia.

  1. The Rotarex® and Aspirex® mechanical thrombectomy devices.

    PubMed

    Horsch, Alexander D; van Oostayen, Jacques; Zeebregts, Clark J; Reijnen, Michel M P J

    2009-04-01

    The Rotarex® and Aspirex® are newly developed over-the-wire rotational thrombectomy catheters. These devices combine mechanical clot fragmentation and active negative-pressure removal of thrombus particles to prevent distal embolization. Several successful in vitro studies have been followed by the pursuit of different applications, and the device has been used successfully in the treatment of acute to chronic thrombo-embolic arterial occlusions in the limbs, hemodialysis access grafts, bypasses, stents, pulmonary artery occlusion, and inferior vena cava and aortohepatic bypass occlusions. Widespread clinical use so far has not been achieved, and more specific indications must be identified to extend the experience with the Rotarex® and Aspirex® devices.

  2. Developments in mechanical thrombectomy devices for the treatment of acute ischemic stroke.

    PubMed

    Mordasini, Pasquale; Gralla, Jan

    2016-01-01

    Several recent prospective randomized controlled trials of endovascular stroke therapy using latest generation thrombectomy devices, so called stent-retrievers, have shown significantly improved clinical outcome compared to the standard treatment with intra-venous thrombolysis using r-tPA alone. Despite some differences in inclusion criteria between these studies, all required non-invasive vessel imaging to proof occlusion of a major brain supplying vessel. Furthermore, in most studies additional imaging techniques were used to exclude patients with already established large cerebral infarction or unfavorable collateral or penumbral status. Patients with small infarct volume, severe neurological deficits and in whom thrombectomy can be initiated within the first 6 hours after symptom onset seem to benefit the most. Therefore, mechanical thrombectomy using stent-retrievers in addition to intra-venous thrombolysis is recommended for the treatment of acute ischemic stroke with proven major vessel occlusion in the anterior circulation.

  3. Mechanical Thrombectomy in Inferior Vena Cava Thrombosis After Caval Filter Placement: A Report of Three Cases

    SciTech Connect

    Poon, W.L.; Luk, S.H.; Yam, K.Y.; Lee, Anselm C.W.

    2002-10-15

    Inferior vena caval (IVC) filter thrombosis inpatients with contraindications to anticoagulant therapy is a difficult and challenging clinical problem. We report our experience in treating three such patients using a mechanical thrombectomy device, which resulted in rapid symptomatic relief until anticoagulant therapy could be safely introduced.

  4. Anesthesia Technique and Outcomes of Mechanical Thrombectomy in Patients With Acute Ischemic Stroke.

    PubMed

    Bekelis, Kimon; Missios, Symeon; MacKenzie, Todd A; Tjoumakaris, Stavropoula; Jabbour, Pascal

    2017-02-01

    The impact of anesthesia technique on the outcomes of mechanical thrombectomy for acute ischemic stroke remains an issue of debate. We investigated the association of general anesthesia with outcomes in patients undergoing mechanical thrombectomy for ischemic stroke. We performed a cohort study involving patients undergoing mechanical thrombectomy for ischemic stroke from 2009 to 2013, who were registered in the New York Statewide Planning and Research Cooperative System database. An instrumental variable (hospital rate of general anesthesia) analysis was used to simulate the effects of randomization and investigate the association of anesthesia technique with case-fatality and length of stay. Among 1174 patients, 441 (37.6%) underwent general anesthesia and 733 (62.4%) underwent conscious sedation. Using an instrumental variable analysis, we identified that general anesthesia was associated with a 6.4% increased case-fatality (95% confidence interval, 1.9%-11.0%) and 8.4 days longer length of stay (95% confidence interval, 2.9-14.0) in comparison to conscious sedation. This corresponded to 15 patients needing to be treated with conscious sedation to prevent 1 death. Our results were robust in sensitivity analysis with mixed effects regression and propensity score-adjusted regression models. Using a comprehensive all-payer cohort of acute ischemic stroke patients undergoing mechanical thrombectomy in New York State, we identified an association of general anesthesia with increased case-fatality and length of stay. These considerations should be taken into account when standardizing acute stroke care. © 2017 American Heart Association, Inc.

  5. Mechanical Thrombectomy in Patients With Acute Ischemic Stroke: A Health Technology Assessment

    PubMed Central

    2016-01-01

    Background In Ontario, current treatment for eligible patients who have an acute ischemic stroke is intravenous thrombolysis (IVT). However, there are some limitations and contraindications to IVT, and outcomes may not be favourable for patients with stroke caused by a proximal intracranial occlusion. An alternative is mechanical thrombectomy with newer devices, and a number of recent studies have suggested that this treatment is more effective for improving functional independence and clinical outcomes. The objective of this health technology assessment was to evaluate the clinical effectiveness and cost-effectiveness of new-generation mechanical thrombectomy devices (with or without IVT) compared to IVT alone (if eligible) in patients with acute ischemic stroke. Methods We conducted a systematic review of the literature, limited to randomized controlled trials that examined the effectiveness of mechanical thrombectomy using stent retrievers and thromboaspiration devices for patients with acute ischemic stroke. We assessed the quality of the evidence using the GRADE approach. We developed a Markov decision-analytic model to assess the cost-effectiveness of mechanical thrombectomy (with or without IVT) versus IVT alone (if eligible), calculated incremental cost-effectiveness ratios using a 5-year time horizon, and conducted sensitivity analyses to examine the robustness of the estimates. Results There was a substantial, statistically significant difference in rate of functional independence (GRADE: high quality) between those who received mechanical thrombectomy (with or without IVT) and IVT alone (odds ratio [OR] 2.39, 95% confidence interval [CI] 1.88–3.04). We did not observe a difference in mortality (GRADE: moderate quality) (OR 0.80, 95% CI 0.60–1.07) or symptomatic intracerebral hemorrhage (GRADE: moderate quality) (OR 1.11, 95% CI 0.66–1.87). In the base-case cost-utility analysis, which had a 5 year time horizon, the costs and effectiveness for

  6. Recanalization with stent-based mechanical thrombectomy in anterior circulation major ischemic stroke.

    PubMed

    Cohen, José E; Gomori, John M; Leker, Ronen R; Moscovici, Samuel; Ramirez-Denoriega, Fernando; Itshayek, Eyal

    2012-01-01

    We report the use of a self-expanding stent as a thrombectomy device in 17 patients (mean age 64.3 years) with major ischemic stroke secondary to large vessel occlusion. The patients had a mean National Institutes of Health Stroke Scale (NIHSS) score of >12, no cerebral hemorrhage or early infarction signs that affected more than 1/3 of the endangered territory, and an insufficient collateral supply. Within 8 hours of symptom onset, a stent (Solitaire; ev3, Irvine, CA, USA) was deployed across the occluded segment (endovascular bypass step). A repeat angiogram was performed to evaluate reconstituted flow. The guide-catheter balloon was inflated for proximal carotid occlusion. The partially deployed stent was slowly pulled back (mechanical thrombectomy step) under continuous aspiration. Complete recanalization (TIMI grade 3 flow) was achieved in fewer than 66 minutes after femoral access in all patients, with complete clot removal in a mean of two thrombectomy attempts. No stent was permanently implanted. Two patients developed asymptomatic hemorrhagic transformation (11.8%). Two patients presented post-recanalization parenchymal hemorrhage (11.8%); one suffered an intracerebral and intraventricular hemorrhage 12 hours after a successful and uneventful procedure and died 10 days later. The modified Rankin Scale scores were 0 to 2 in 15 patients (88.2%) and 3 in one patient (5.9%) at 1 month. In our preliminary experience, rapid stent-based mechanical thrombectomy has had unprecedented success. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. Twelve months outcome after percutaneous mechanical thrombectomy for treatment of acute femoropopliteal bypass occlusion.

    PubMed

    Lichtenberg, Michael; Stahlhoff, Wilhelm; Boese, Dirk; Hailer, Birgit

    2013-04-01

    Acute and subacute ischemia of the legs in acute and subacute femoropopliteal bypass occlusion is a dramatic situation that endangers the survival of the limbs, depending on the severity of the ischemia. Different therapy options like percutaneous mechanical thrombectomy procedures, which include rotational thrombectomy, have become available in recent years in addition to local lysis and surgical thrombectomy. Rotational thrombectomy with the Straub Rotarex(®) System as an endovascular therapy option has demonstrated promising results leading to amputation-free survival in multiple studies. We recently provided data of 22 patients with acute femoropopliteal bypass occlusion where we examined the feasibility of the Rotarex(®) System in this indication. A technical success rate of 82% was demonstrated. During a follow-up period of 6 months, no reinterventions in these patients had to be performed. We now provide patency rates in 21 patients of our study group after a follow-up period of 12 months. The average ABI after 12 months was 0.80 ± 0.1. One patient showed a hemodynamic restenosis in a Nitinolstent distal to the femoropopliteal bypass which was implanted in the index procedure. No reocclusion of the femoropopliteal bypasses occurred in all patients.

  8. Conscious sedation versus general anaesthesia during mechanical thrombectomy for stroke: a propensity score analysis.

    PubMed

    McDonald, Jennifer S; Brinjikji, Waleed; Rabinstein, Alejandro A; Cloft, Harry J; Lanzino, Giuseppe; Kallmes, David F

    2015-11-01

    Debate exists as to whether patients with acute ischemic stroke who are undergoing mechanical thrombectomy should receive general anaesthesia or conscious sedation during the procedure. Using a multihospital administrative database, we compared outcomes and complications of patients receiving mechanical thrombectomy, who were receiving general anaesthesia and conscious sedation, and studied trends in usage over time. Premier database patients who underwent mechanical thrombectomy from 2006 to 2013 for acute ischemic stroke were identified. Using propensity score analysis, recipients of general anaesthesia and conscious sedation underwent 1:1 matching. Outcomes including usage trends, discharge status, mortality, length of stay, haemorrhage and pneumonia were examined. A total of 2512 patients receiving mechanical thrombectomy were identified. 1999 (80%) received general anaesthesia and 513 (20%) received conscious sedation. Following 1:1 matching by the propensity score matching, 507 general anaesthesia and 507 conscious sedation patients were matched. Patients who received general anaesthesia during their procedure had significantly higher rates of in-hospital mortality (25% vs 12%, OR=2.37 95% CI 1.68 to 3.37, p<0.0001), and pneumonia (17.0% vs 9.3%, OR=2.0, 95% CI 1.35 to 2.96, p=0.0005) compared with patients of thrombectomy who received conscious sedation. ICH/SAH rates were similar between patients receiving general anaesthesia and patients receiving conscious sedation (11% vs 12%, p=0.62). Usage rate of general anaesthesia decreased from 83.8% in 2006 and 74.0% in 2013. In our cohort, thrombectomy patients receiving conscious sedation have decreased in-hospital mortality, decreased rates of pneumonia, and lower hospital costs and lengths of stay when compared with patients who received general anaesthesia. However, most practitioners continue to use general anaesthesia in the setting of acute stroke interventions. Published by the BMJ Publishing Group

  9. Successful Mechanical Thrombectomy in a 2-Year-Old Male Through a 4-French Guide Catheter

    PubMed Central

    Stidd, David A.

    2014-01-01

    A 2-year-old boy with hypoplastic left heart syndrome that required multiple cardiovascular surgeries and a heterozygous prothrombin G20210A mutation with resulting thrombophilia maintained on warfarin presented with acute right middle cerebral artery (MCA) infarction manifesting as a left hemiplegia. An MRI revealed a complete occlusion of the right M1 segment with an area of restricted diffusion in the right basal ganglia representing only a small area of acute infarction. Patchy areas of subacute infarction were also present in the right MCA territory. He underwent endovascular mechanical thrombectomy with a stent retriever. This is an account of a successful mechanical thrombectomy performed in the youngest patient reported in the English literature to date. PMID:25426305

  10. Basilar artery occlusion in a child treated successfully with mechanical thrombectomy using ADAPT.

    PubMed

    Lena, Jonathan; Eskandari, Ramin; Infinger, Libby; Fargen, Kyle M; Spiotta, Alejandro; Turk, Aquilla; Turner, Raymond D; Chaudry, Imran

    2017-01-01

    Acute ischemic stroke (AIS) in the pediatric population is rare. Furthermore, it is common for physicians to take significantly longer diagnosing a posterior circulation stroke in a child than in an adult. There are increasing case reports in the literature of treating AIS in children with intravenous tissue plasminogen activator, intra-arterial thrombolysis, and/or mechanical thrombectomy. We present the first case of pediatric AIS treated using a direct aspiration first pass technique (ADAPT) as a means of mechanical thrombectomy. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  11. Clinical and radiological outcome after mechanical thrombectomy in acute ischemic stroke: What matters?

    PubMed

    Kaschka, Iris N; Kloska, Stephan P; Struffert, Tobias; Engelhorn, Tobias; Gölitz, Philipp; Kurka, Natalia; Köhrmann, Martin; Schwab, Stefan; Doerfler, Arnd

    2016-04-01

    Recent studies have shown the efficacy of mechanical thrombectomy in acute ischemic stroke. We sought to identify prognostic parameters for clinical and radiological outcome after mechanical thrombectomy. In 34 patients (age 72 ± 13 years, 64.7% women) with acute occlusion of the distal ICA and/or M1 segment who were treated with mechanical thrombectomy, the Spearman correlation was performed to assess potential prognostic outcome parameters (age, NIHSS, ASPECT, thrombus length (TL), clot burden score (CBS), relative filling time delay (rFTD), time to recanalization (TTR) and TICI score). The modified Rankin scale (mRS) and the Alberta Stroke Program Early CT (ASPECT) score were used for clinical and radiological outcome, respectively. Receiver operating characteristic (ROC) analysis was performed to assess parameters predicting favorable clinical (ΔmRS ≤ 2) and radiological outcome (ΔASPECT ≤ 2). Variables associated with favorable clinical outcome included NIHSS, TL, TTR and TICI score (p ≤ 0.01) with NIHSS ≤ 15 (p = 0.001, area under the curve (AUC) 0.87), TL ≤ 2 cm (p = 0.017, AUC 0.75), TTR ≤ 231 min (p = 0.001 AUC 0.88) and TICI ≥ 2b (p = 0.050, AUC 0.70). Shorter TTR and higher TICI scores were associated with favorable radiological outcome (p < 0.001) with TTR ≤ 224 min (p = 0.023, AUC 0.77) and TICI ≥ 2b (p = 0.000, AUC 0.86). Fast and complete recanalization is essential to achieve a favorable radiological and functional outcome after mechanical thrombectomy in acute ischemic stroke. Age, CBS and collateral supply play a subordinate role. © The Author(s) 2016.

  12. Clinical and radiological outcome after mechanical thrombectomy in acute ischemic stroke: What matters?

    PubMed Central

    Kloska, Stephan P; Struffert, Tobias; Engelhorn, Tobias; Gölitz, Philipp; Kurka, Natalia; Köhrmann, Martin; Schwab, Stefan; Doerfler, Arnd

    2016-01-01

    Objective Recent studies have shown the efficacy of mechanical thrombectomy in acute ischemic stroke. We sought to identify prognostic parameters for clinical and radiological outcome after mechanical thrombectomy. Methods In 34 patients (age 72 ± 13 years, 64.7% women) with acute occlusion of the distal ICA and/or M1 segment who were treated with mechanical thrombectomy, the Spearman correlation was performed to assess potential prognostic outcome parameters (age, NIHSS, ASPECT, thrombus length (TL), clot burden score (CBS), relative filling time delay (rFTD), time to recanalization (TTR) and TICI score). The modified Rankin scale (mRS) and the Alberta Stroke Program Early CT (ASPECT) score were used for clinical and radiological outcome, respectively. Receiver operating characteristic (ROC) analysis was performed to assess parameters predicting favorable clinical (ΔmRS ≤ 2) and radiological outcome (ΔASPECT ≤ 2). Results Variables associated with favorable clinical outcome included NIHSS, TL, TTR and TICI score (p ≤ 0.01) with NIHSS ≤ 15 (p = 0.001, area under the curve (AUC) 0.87), TL ≤ 2 cm (p = 0.017, AUC 0.75), TTR ≤ 231 min (p = 0.001 AUC 0.88) and TICI ≥ 2b (p = 0.050, AUC 0.70). Shorter TTR and higher TICI scores were associated with favorable radiological outcome (p < 0.001) with TTR ≤ 224 min (p = 0.023, AUC 0.77) and TICI ≥ 2b (p = 0.000, AUC 0.86). Conclusion Fast and complete recanalization is essential to achieve a favorable radiological and functional outcome after mechanical thrombectomy in acute ischemic stroke. Age, CBS and collateral supply play a subordinate role. PMID:26932163

  13. Mechanical thrombectomy with Solitaire AB stents for the treatment of intracranial venous sinus thrombosis.

    PubMed

    Ma, Ji; Shui, Shaofeng; Han, XinWei; Guo, Dong; Li, Teng-Fei; Yan, Lei

    2016-12-01

    Background Cerebral venous sinus thrombosis (CVST) is a rare clinicopathological entity with substantial diagnostic and therapeutic dilemmas. The appropriate management of CVST remains to be defined. Purpose To evaluate the efficiency and safety of mechanical thrombectomy with Solitaire AB stents for the treatment of intracranial venous sinus thrombosis. Material and Methods Twenty-three consecutive patients with CVST who were treated with mechanical thrombectomy using Solitaire AB stents between January 2013 and October 2014 were retrospectively analyzed. The headache intensity was evaluated according to the visual analogue scale (VAS), and neurological function was assessed using the National Institute of Health Stroke Scale (NIHSS). Follow-up data were available for all patients for 6-14 months. Magnetic resonance imaging (MRI) and magnetic resonance venography (MRV) were performed at 3 and 6 months after neurointervention, and telephone interviews were performed monthly thereafter. The Wilcoxon signed-rank test was used to compare the evaluation data (VAS and NIHSS) at admission and discharge. Results Twenty-six Solitaire AB stents were used. No neurointervention-related complications were noted. The symptoms were significantly improved after neurointervention in all patients. The comparisons between the VAS and NIHSS evaluations at admission and discharge were significantly different ( P < 0.05). No recurrence was observed during the follow-up period. Conclusion Mechanical thrombectomy with Solitaire AB stents is safe and effective for the treatment of CVST and can significantly improve clinical symptoms. The occurrence of complications is low, and the prognosis is favorable.

  14. Mechanical Thrombectomy of Iliac Vein Thrombosis in a Pig Model Using the Rotarex and Aspirex Catheters

    SciTech Connect

    Minko, P. Bücker, A.

    2013-06-08

    PurposeTo investigate the efficacy and safety of mechanical thrombectomy for iliac vein thrombosis using Rotarex and Aspirex catheters in a pig model.Materials and MethodsIliac vein thrombosis was induced in six pigs by means of an occlusion-balloon catheter and thrombin injection. The presence of thrombi was verified by digital subtraction angiography (DSA) and computed tomography (CT). Thrombectomy was performed using 6F and 8F Rotarex and 6F, 8F, and 10F Aspirex catheters (Straub Medical AG, Wangs, Switzerland). After intervention, DSA and CT were repeated to evaluate the efficacy of mechanical thrombectomy and to exclude local complications. In addition, pulmonary CT was performed to rule out pulmonary embolism. Finally, all pigs were killed, and iliac veins were dissected to perform macroscopic and histological examination.ResultsThrombus induction was successfully achieved in all animals as verified by DSA and CT. Subsequent thrombectomy lead to incomplete recanalization of the iliac veins with residual thrombi in all cases. However, the use of the 6F and 8F Rotarex catheters caused vessel perforation and retroperitoneal hemorrhage in all cases. Application of the Aspirex device caused one small transmural perforation in a vessel treated with a 10F Aspirex catheter, and this was only seen microscopically. Pulmonary embolism was detected in one animal treated with the Rotarex catheters, whereas no pulmonary emboli were seen in animals treated with the Aspirex catheters.ConclusionThe Aspirex catheter allowed subtotal and safe recanalization of iliac vein thrombosis. In contrast, the use of the Rotarex catheter caused macroscopically obvious vessel perforations in all cases.

  15. [Mechanical thrombectomy using Solitaire AB stent for acute middle cerebral artery occlusion with atrial fibrillation].

    PubMed

    Zhu, Xucheng; Peng, Ya; Xuan, Jinggang; Chen, Ronghua; Shao, Huaming; Cao, Jie; Yang, Yilin

    2015-10-20

    To investigate the endovascular management strategy of mechanical thrombectomy using Solitaire AB stent for acute middle cerebral artery occlusion with atrial fibrillation and assess the safety and efficacy. From June 2012 to Dec 2013, 40 patients of acute middle cerebral artery occlusion with atrial fibrillation admitted to our institutes were treated by Solitaire AB stent.Clinical status was evaluated by the score of National Institute of Health Stroke Scale (NIHSS) before and 72 hours after treatment, immediate scale of thrombolysis in cerebral infarction (TICI) after thrombectomy, the 90 d score of Modified Rankin Scale (mRS).The patients were classified into good result group (mRS≤2) and bad result group (mRS>2) according to the mRS score. Out of 40 cases, there were 28 cases caused by cardiogenic embolism. Recanalization was successful (TICI score 2b or 3) in 37 out of 40 (92.5%). 90 d follow-up mRS was 0-2 in 19 of 40 patients (47.5%). 3-5 in 21 patients (52.5%). 5 patients died (12.5%).Symptomatic hemorrhagic transform developed in 6 patients (15%).No complications related to the Solitaire AB thrombectomy occurred.Mean time from symptom onset to recanalization (312±52 min vs 370±68 min, P<0.05) and initial NIHSS score (17.0±0.4 vs 18.6±0.4, P<0.05) were of significant difference between good result group and bad result group. These results confirm that mechanical thrombectomy using solitaire AB stent for acute middle cerebral artery occlusion with atrial fibrillation is safe and effective.

  16. Mechanical thrombectomy for acute ischemic stroke: final results of the Multi MERCI trial.

    PubMed

    Smith, Wade S; Sung, Gene; Saver, Jeffrey; Budzik, Ronald; Duckwiler, Gary; Liebeskind, David S; Lutsep, Helmi L; Rymer, Marilyn M; Higashida, Randall T; Starkman, Sidney; Gobin, Y Pierre; Frei, Donald; Grobelny, Thomas; Hellinger, Frank; Huddle, Dan; Kidwell, Chelsea; Koroshetz, Walter; Marks, Michael; Nesbit, Gary; Silverman, Isaac E

    2008-04-01

    Endovascular mechanical thrombectomy may be used during acute ischemic stroke due to large vessel intracranial occlusion. First-generation MERCI devices achieved recanalization rates of 48% and, when coupled with intraarterial thrombolytic drugs, recanalization rates of 60% have been reported. Enhancements in embolectomy device design may improve recanalization rates. Multi MERCI was an international, multicenter, prospective, single-arm trial of thrombectomy in patients with large vessel stroke treated within 8 hours of symptom onset. Patients with persistent large vessel occlusion after IV tissue plasminogen activator treatment were included. Once the newer generation (L5 Retriever) device became available, investigators were instructed to use the L5 Retriever to open vessels and could subsequently use older generation devices and/or intraarterial tissue plasminogen activator. Primary outcome was recanalization of the target vessel. One hundred sixty-four patients received thrombectomy and 131 were initially treated with the L5 Retriever. Mean age+/-SD was 68+/-16 years, and baseline median (interquartile range) National Institutes of Health Stroke Scale score was 19 (15 to 23). Treatment with the L5 Retriever resulted in successful recanalization in 75 of 131 (57.3%) treatable vessels and in 91 of 131 (69.5%) after adjunctive therapy (intraarterial tissue plasminogen activator, mechanical). Overall, favorable clinical outcomes (modified Rankin Scale 0 to 2) occurred in 36% and mortality was 34%; both outcomes were significantly related to vascular recanalization. Symptomatic intracerebral hemorrhage occurred in 16 patients (9.8%); 4 (2.4%) of these were parenchymal hematoma type II. Clinically significant procedural complications occurred in 9 (5.5%) patients. Higher rates of recanalization were associated with a newer generation thrombectomy device compared with first-generation devices, but these differences did not achieve statistical significance. Mortality

  17. Prospective, multicenter, single-arm study of mechanical thrombectomy using Solitaire Flow Restoration in acute ischemic stroke.

    PubMed

    Pereira, Vitor M; Gralla, Jan; Davalos, Antoni; Bonafé, Alain; Castaño, Carlos; Chapot, René; Liebeskind, David S; Nogueira, Raul G; Arnold, Marcel; Sztajzel, Roman; Liebig, Thomas; Goyal, Mayank; Besselmann, Michael; Moreno, Antonio; Moreno, Alfredo; Schroth, Gerhard

    2013-10-01

    Mechanical thrombectomy using stent retriever devices have been advocated to increase revascularization in intracranial vessel occlusion. We present the results of a large prospective study on the use of the Solitaire Flow Restoration in patients with acute ischemic stroke. Solitaire Flow Restoration Thrombectomy for Acute Revascularization was an international, multicenter, prospective, single-arm study of Solitaire Flow Restoration thrombectomy in patients with large vessel anterior circulation strokes treated within 8 hours of symptom onset. Strict criteria for site selection were applied. The primary end point was the revascularization rate (thrombolysis in cerebral infarction ≥2b) of the occluded vessel as determined by an independent core laboratory. The secondary end point was the rate of good functional outcome (defined as 90-day modified Rankin scale, 0-2). A total of 202 patients were enrolled across 14 comprehensive stroke centers in Europe, Canada, and Australia. The median age was 72 years, 60% were female patients. The median National Institute of Health Stroke Scale was 17. Most proximal intracranial occlusion was the internal carotid artery in 18%, and the middle cerebral artery in 82%. Successful revascularization was achieved in 79.2% of patients. Device and procedure-related severe adverse events were found in 7.4%. Favorable neurological outcome was found in 57.9%. The mortality rate was 6.9%. Any intracranial hemorrhagic transformation was found in 18.8% of patients, 1.5% were symptomatic. In this single-arm study, treatment with the Solitaire Flow Restoration device in intracranial anterior circulation occlusions results in high rates of revascularization, low risk of clinically relevant procedural complications, and good clinical outcomes in combination with low mortality at 90 days. http://www.clinicaltrials.gov. Unique identifier: NCT01327989.

  18. Is there a benefit of mechanical thrombectomy in patients with large stroke (DWI-ASPECTS≤ 5)?

    PubMed

    Manceau, Pierre-François; Soize, Sébastien; Gawlitza, Matthias; Fabre, Guillaume; Bakchine, Serge; Durot, Carole; Serre, Isabelle; Metaxas, Georgios-Emmanouil; Pierot, Laurent

    2017-09-14

    Whether to withhold mechanical thrombectomy when the diffusion-weighted imaging (DWI) lesion exceeds a given volume is undetermined. We aimed to identify markers that will help to select patients with large DWI lesions (DWI-Alberta Stroke Program Early CT Score, DWI-ASPECTS≤5) that may benefit from thrombectomy. From May 2010 to November 2016, we studied 82 acute ischemic stroke patients with DWI-ASPECTS≤5 (43 men, 64.6±14.4 years, NIHSS 18.4±5.4) treated with state-of-the-art mechanical thrombectomy. Thrombectomy alone was performed in 28 (34%) and bridging therapy in 54 (66%) patients. Recanalization was defined as a thrombolysis in cerebral infarction (TICI) score 2B-3 and significant hemorrhagic transformation as parenchymal hematoma type 2 (European Cooperative Acute Stroke Study 3 classification). Pretreatment variables were compared between patients with a good (mRS 0-2) and a poor (mRS 3-6) neurological outcome at 3 months. Overall, 28 patients (34%) achieved good neurological outcome at 3 months. Recanalizers were significantly more likely to achieve good outcome (61% vs 7.3%, P<0.0001), had lower mortality (24% vs 49%, P=0.03) and similar rates of parenchymal hematoma type 2 (9.8% vs 7.3%, P=1) compared to non-recanalizers. Regression modeling identified DWI-ASPECTS>2 (OR 6.93; 95%CI 1.05-45.76, P=0.04), glycemia ≤6.8 mmol/l (OR 4.05; 95%CI 1.09-15.0, P=0.03) and thrombolysis (OR 3.67; 95%CI 1.04-12.9, P=0.04) as independent predictors of good neurological outcome. In patients with DWI-ASPECTS≤5, 2/3 of patients experienced good neurological outcome when recanalized by state-of-the-art thrombectomy, while only 1/14 non-recanalizers achieved similar outcomes. Pretreatment markers of good neurological outcomes were DWI-ASPECTS>2, intravenous thrombolysis and glycemia≤6.8 mmol/l. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  19. Efficacy and Safety of Thrombectomy Combined with Intracoronary Administration of Tirofiban in ST-segment Elevation Myocardial Infarction (STEMI).

    PubMed

    Gao, Lu; Cao, Zhenhua; Zhang, Hong

    2016-07-31

    BACKGROUND No/slow reflow gives rise to serious complications in STEMI patients undergoing PCI, and can lead to worse outcomes. Several measures are used to prevent no/slow reflow, including thrombus removal processes and intensive use of anticoagulant agents. Our study was designed to evaluate the efficacy and safety of thrombectomy and intracoronary administration of GPIIb/IIIa inhibitors in STEMI patients undergoing PPCI. MATERIAL AND METHODS We randomly assigned 240 STEMI patients into 3 groups. Before PPCI, patients in group A received thrombectomy and intracoronary administration of tirofiban. Patients in group B received thrombectomy, and patients in group C neither of these 2 treatments. Their demographic data and coronary angiography results were recorded. TIMI grade flow was used to evaluate the effect. After the follow-up, major adverse cardiac events were regarded as study endpoints in evaluating the safety of the combined therapy. RESULTS We found no significant differences among the 3 groups in demographic and clinical characteristics (p>0.05). Patients in group A had better TIMI grade classifications and ST-segment elevation (p=0.005), and lower incidence of no/slow reflow (p=0.031) and MACE. During 6-month follow-up, the MACE rate was lower in group A than in groups B and C (p=0.038). CONCLUSIONS The use of thrombectomy combined with intracoronary administration of tirofiban is relatively effective and safe in STEMI patients undergoing PPCI.

  20. Efficacy, safety, and clinical outcome of modern mechanical thrombectomy in elderly patients with acute ischemic stroke.

    PubMed

    Son, Seungnam; Kang, Dong-Hun; Hwang, Yang-Ha; Kim, Yong-Sun; Kim, Yong-Won

    2017-07-20

    The average life expectancy is increasing worldwide, surpassing 80 years in some countries. Recently, mechanical thrombectomy (MT) using modern devices and techniques has led to improved clinical outcomes following acute ischemic stroke. However, thus far, it remains uncertain whether MT is effective in elderly patients aged over 80 years. Between July 2013 and June 2016, 207 patients with acute ischemic stroke in the anterior circulation received MT at our center. The applied MT strategies were forced arterial suction thrombectomy (FAST) and stent retriever thrombectomy. Patients were divided into those <80 years (n = 173) and those ≥80 years (n = 34). We compared clinical and angiographic parameters between groups. The median age was 67.5 in the younger group and 82 in the elderly group; 92.5% of the younger group and 70.6% of the elderly group received MT via the FAST technique. Angiographic outcomes, including procedural time, mTICI 2b-3 reperfusion (85.5% vs. 82.4%, p = 0.633), and symptomatic intracranial hemorrhage, were not different between the groups. A favorable clinical outcome rate was significantly higher in the younger group (62.4% vs. 44.1%, p = 0.047). Younger age, a low NIHSS score, and fast onset to reperfusion time were favorable prognostic factors in elderly patients. Modern MT in elderly patients with acute ischemic stroke is safe and effective compared to younger patients despite a lower favorable clinical outcome. Our findings may suggest that an appropriate MT strategy with respect to the location of the target occlusion and vascular tortuosity might be helpful to achieve fast reperfusion and improved outcomes for elderly patients.

  1. Revolution in acute ischaemic stroke care: a practical guide to mechanical thrombectomy.

    PubMed

    Evans, Matthew R B; White, Phil; Cowley, Peter; Werring, David J

    2017-08-01

    Rapid, safe and effective arterial recanalisation to restore blood flow and improve functional outcome remains the primary goal of hyperacute ischaemic stroke management. The benefit of intravenous thrombolysis with recombinant tissue-type plasminogen activator for patients with severe stroke due to large artery occlusion is limited; early recanalisation is generally less than 30% for carotid, proximal middle cerebral artery or basilar artery occlusion. Since November 2014, nine positive randomised controlled trials of mechanical thrombectomy for large vessel occlusion in the anterior circulation have led to a revolution in the care of patients with acute ischaemic stroke. Its efficacy is unmatched by any previous therapy in stroke medicine, with a number needed to treat of less than 3 for improved functional outcome. With effectiveness shown beyond any reasonable doubt, the key challenge now is how to implement accessible, safe and effective mechanical thrombectomy services. This review aims to provide neurologists and other stroke physicians with a summary of the evidence base, a discussion of practical aspects of delivering the treatment and future challenges. We aim to give guidance on some of the areas not clearly described in the clinical trials (based on evidence where available, but if not, on our own experience and practice) and highlight areas of uncertainty requiring further research. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  2. Revolution in acute ischaemic stroke care: a practical guide to mechanical thrombectomy

    PubMed Central

    Evans, Matthew R B; White, Phil; Cowley, Peter; Werring, David J

    2017-01-01

    Rapid, safe and effective arterial recanalisation to restore blood flow and improve functional outcome remains the primary goal of hyperacute ischaemic stroke management. The benefit of intravenous thrombolysis with recombinant tissue-type plasminogen activator for patients with severe stroke due to large artery occlusion is limited; early recanalisation is generally less than 30% for carotid, proximal middle cerebral artery or basilar artery occlusion. Since November 2014, nine positive randomised controlled trials of mechanical thrombectomy for large vessel occlusion in the anterior circulation have led to a revolution in the care of patients with acute ischaemic stroke. Its efficacy is unmatched by any previous therapy in stroke medicine, with a number needed to treat of less than 3 for improved functional outcome. With effectiveness shown beyond any reasonable doubt, the key challenge now is how to implement accessible, safe and effective mechanical thrombectomy services. This review aims to provide neurologists and other stroke physicians with a summary of the evidence base, a discussion of practical aspects of delivering the treatment and future challenges. We aim to give guidance on some of the areas not clearly described in the clinical trials (based on evidence where available, but if not, on our own experience and practice) and highlight areas of uncertainty requiring further research. PMID:28647705

  3. Vessel wall magnetic resonance imaging in acute ischemic stroke: effects of embolism and mechanical thrombectomy on the arterial wall.

    PubMed

    Power, Sarah; Matouk, Charles; Casaubon, Leanne K; Silver, Frank L; Krings, Timo; Mikulis, David J; Mandell, Daniel M

    2014-08-01

    The aim of the study was to determine the effects of thromboembolism and mechanical thrombectomy on the vessel wall magnetic resonance imaging (VW-MRI) appearance of the intracranial arterial wall. This was a cross-sectional study of consecutive patients with acute intracranial arterial occlusion who underwent high-resolution contrast-enhanced VW-MRI within days of stroke presentation. For each patient, we categorized arterial wall thickening and enhancement as definite, possible, or none using contralateral arteries as a reference standard. We performed χ(2) tests to compare the effects of medical therapy and mechanical thrombectomy. Sixteen patients satisfied inclusion criteria. Median time from symptom onset to VW-MRI was 3 days (interquartile range, 2 days). Among 6 patients treated with mechanical thrombectomy using a stent retriever, VW-MRI demonstrated definite arterial wall thickening in 5 (83%) and possible thickening in 1 (17%); there was definite wall enhancement in 4 (67%) and possible enhancement in 2 (33%). Among 10 patients treated with medical therapy alone, VW-MRI demonstrated definite arterial wall thickening in 3 (30%) and possible thickening in 2 (20%); there was definite wall enhancement in 2 (20%) and possible enhancement in 2 (20%). Arterial wall thickening and enhancement were more common in patients treated with mechanical thrombectomy than with medical therapy alone (P=0.037 and P=0.016, respectively). Mechanical thrombectomy results in intracranial arterial wall thickening and enhancement, potentially mimicking the VW-MRI appearance of primary arteritis. This arterial wall abnormality is less common in patients with arterial occlusion who have been treated with medical therapy alone. © 2014 American Heart Association, Inc.

  4. Prospective, Multi-Centre, Single-Arm Study of Mechanical Thrombectomy using Solitaire FR in Acute Ischemic Stroke-STAR

    PubMed Central

    Pereira, Vitor M; Gralla, Jan; Davalos, Antoni; Bonafé, Alain; Castaño, Carlos; Chapot, Rene; Liebeskind, David S; Nogueira, Raul G; Arnold, Marcel; Sztajzel, Roman; Liebig, Thomas; Goyal, Mayank; Besselmann, Michael; Moreno, Alfredo; Schroth, Gerhard

    2013-01-01

    Background and Purpose Mechanical thrombectomy using stent retriever devices have been advocated to increase revascularization in intracranial vessel occlusion. We present the results of a large prospective study on the use of the Solitaire FR in patients with acute ischemic stroke. Methods STAR was an international, multicenter, prospective, single-arm study of Solitaire FR thrombectomy in patients with large vessel anterior circulation strokes treated within 8 hours of symptom onset. Strict criteria for site selection were applied. The primary endpoint was the revascularization rate (3TICI 2b) of the occluded vessel as determined by an independent core lab. The secondary endpoint was the rate of good functional outcome (defined as 90-day modified Rankin scale (mRS) 0–2). Results A total of 202 patients were enrolled across 14 comprehensive stroke centers in Europe, Canada and Australia. The median age was 72 years, 60% were female patients. The median National Institute of Health Stroke Scale (NIHSS) was 17. Most proximal intracranial occlusion was the internal carotid artery in 18%, the middle cerebral artery in 82%. Successful revascularization was achieved in 79.2% of patients. Device and/or procedure related severe adverse events were found in 7.4%. Favorable neurological outcome was found in 57.9%. The mortality rate was 6.9%. Any intracranial hemorrhagic transformation was found in 18.8% of patients, 1.5% were symptomatic. Conclusions In this single arm study, treatment with the Solitaire™ FR device in intracranial anterior circulation occlusions results in high rates of revascularization, low risk of clinically relevant procedural complications, and good clinical outcomes in combination with low mortality at 90 days. Clinical Trial Registration This study is registered with ClinicalTrials.gov, number NCT01327989. PMID:23908066

  5. Mechanical Thrombectomy in the Treatment of Distal Occlusions during Coil Embolization of Ruptured Intracranial Aneurysms

    PubMed Central

    Briganti, Francesco; Leone, Giuseppe; Marseglia, Mariano; Chiaramonte, Carmela; Solari, Domenico; Caranci, Ferdinando; Cappabianca, Paolo; Maiuri, Francesco

    2016-01-01

    The experience in the management of thromboembolic complications of distal vessels during coil embolization using stent-retrievers in the setting of subarachnoid hemorrhage (SAH) is still limited. We report a case of 58-year-old woman with a ruptured small anterior communicating aneurysm who experienced during coil embolization a thromboembolic occlusion of the upper post-bifurcation branch of the middle cerebral artery. Mechanical thrombectomy with a stent-retriever (Solitaire, Covidien, Neurovascular) resulted in complete recanalization of the occluded branch with no ischemic complication. This case should encourage the use of the Solitaire device as an effective rescue strategy in the treatment of distal artery occlusions in the setting of SAH. PMID:28664011

  6. Combined Multimodal Computed Tomography Score Correlates With Futile Recanalization After Thrombectomy in Patients With Acute Stroke.

    PubMed

    Espinosa de Rueda, Mariano; Parrilla, Guillermo; Manzano-Fernández, Sergio; García-Villalba, Blanca; Zamarro, Joaquín; Hernández-Fernández, Francisco; Sánchez-Vizcaino, Cristina; Carreón, Ester; Morales, Ana; Moreno, Antonio

    2015-09-01

    Futile recanalization after acute ischemic stroke occurs in almost half of the patients despite optimal angiographic results. Multimodal neuroimaging may help to improve patient's selection but is still dismissed by many interventionalists. Our aim was to evaluate the accuracy of each parameter of multimodal computed tomography (CT) and their combination for predicting futile recanalization after successful thrombectomy. We retrospectively reviewed a cohort of consecutive patients with anterior circulation stroke, fully assessable multimodal CT, and successful recanalization. Nonenhanced CT, CT angiography source images, cerebral blood volume (CBV), cerebral blood flow (CBF), and mismatch CBV-CBF maps were studied by Alberta Stroke Program Early CT Score (ASPECTS); collaterals on CT angiography were graded as poor or good (≤50% or >50% of the middle cerebral artery territory). Futile recanalization was defined as modified Rankin Scale score >2 at 3 months despite successful recanalization. One hundred fifty patients were included and 57% of them had futile recanalization. They had lower ASPECTS on nonenhanced CT, CT angiography source images, CBV, CBF, and mismatch CBV-CBF and presented more frequently poor collaterals (all P<0.001). Among them, CBV showed the highest area under the curve (0.83; 95% confidence interval, 0.76-0.88). In multivariate analyses, CT angiography source images ≤5 (odds ratio, 5.1; 95% confidence interval, 1.2-21.9), CBV≤6 (odds ratio, 3.5; 95% confidence interval, 1.2-9.7), and poor collaterals (odds ratio, 8.6; 95% confidence interval, 1.8-41.7) were independent predictors of futile recanalization. A combined score of these 3 parameters added complementary information: 57% of the patients with score-1, 89% with score-2, and 100% with score-3 had futile recanalization. Reclassification analyses indicated that this score improved prediction of futile recanalization. In this population, a combined multimodal CT score predicted futile

  7. Transjugular Intrahepatic Portosystemic Shunt, Mechanical Aspiration Thrombectomy, and Direct Thrombolysis in the Treatment of Acute Portal and Superior Mesenteric Vein Thrombosis

    SciTech Connect

    Ferro, Carlo; Rossi, Umberto G. Bovio, Giulio; Dahamane, M'Hamed; Centanaro, Monica

    2007-09-15

    A patient was admitted because of severe abdominal pain, anorexia, and intestinal bleeding. Contrast-enhanced multidetector computed tomography demonstrated acute portal and superior mesenteric vein thrombosis (PSMVT). The patient was treated percutaneously with transjugular intrahepatic portosystemic shunt (TIPS), mechanical aspiration thrombectomy, and direct thrombolysis, and 1 week after the procedure, complete patency of the portal and superior mesenteric veins was demonstrated. TIPS, mechanical aspiration thrombectomy, and direct thrombolysis together are promising endovascular techniques for the treatment of symptomatic acute PSMVT.

  8. Catheter-directed thrombolysis combined with manual aspiration thrombectomy for acute inferior vena cava filter thrombosis.

    PubMed

    Li, Wen D; Li, Cheng L; Qian, Ai M; Zhang, Ye Q; Li, Xiao Q

    2016-12-01

    The occurrence of inferior vena cava (IVC) filter thrombosis has been reported, however, the optimal treatment of IVC thrombosis has not been established yet. The aim of this study was to assess the results of catheter-directed thrombolysis (CDT) combined with aspiration thrombectomy (AT) in the treatment for IVC filter thrombosis. A total of 35 consecutive patients received endovascular treatment with CDT alone or CDT with AT for IVC filter thrombosis at Second Affiliated Hospital of Suzhou University from May 2009 to May 2014 were included in this study. The procedure, complications and clinical outcome between these two groups were retrospectively reviewed. The mean age of patients was 44.7±15.8 years (range: 17-74 years). The patients were consisted of 21 males and 14 females. CDT alone and CDT with AT were performed in 16 and 19 patients, respectively. The mean procedural time in the group receiving CDT alone group was longer than in the group receiving CDT with AT (99.5±51.4 vs. 64.9±35.9 hours, P<0.05) and the dose of urokinase used during the procedure was significantly lower in the CDT + AT group (2.1±1.1 vs. 1.5±0.6 million IU, P<0.05). Besides, total number of complications in the CDT + AT group was smaller than in the group treated with CDT alone (9 vs. 4 cases, P<0.05). Our results confirmed that CDT with AT was a safe and effective method in the treatment of acute IVC filter thrombosis. Compared with CDT alone, it was better performing thanks to a shorter thrombolysis time and a lower urokinase dose required. In addition, it may decrease the occurrence of complications.

  9. Unsuccessful percutaneous mechanical thrombectomy in fibrin-rich high-risk pulmonary thromboembolism.

    PubMed

    Vidmar, Jernej; Serša, Igor; Kralj, Eduard; Popovič, Peter

    2015-01-01

    We report a case of unsuccessful percutaneous mechanical thrombectomy in treatment of a high-risk pulmonary embolism (PE). Pulmonary thromboemboli are commonly expected as a homogenous mass, rich with red blood cell content, which respond well to percutaneous mechanical thrombectomy (PMT). Catheter-based approach or surgical embolectomy are two treatment options that are usually considered for treatment of high-risk PE when the thrombolytic therapy fails or it is contraindicated due to a patient's persisting hemodynamic compromise. Currently, selection criteria for PE treatment options are based mostly on the assessment of patient's history. The aim of this report is to highlight a possible treatment complication in PMT of structurally heterogeneous thrombotic mass due to PMT inadequacy. A 32 year-old male with polytrauma was admitted to an intensive care unit after a right-sided nephrectomy and evacuation of retroperitoneal hematoma. The patient initial haemostatic disorder was improved by administration of blood preparations, an anti-fibrinolytic agent and concentrates of fibrinogen. On the third day he presented sudden onset of hemodynamic instability and was incapable of standard CTA diagnostic procedure. Urgent and relevant investigations including transthoracic and transesophageal echocardiogram confirmed a high-risk PE. PMT was performed due to contraindications for systemic thrombolysis. Long-term PMT was attempted using aspiration with several devices. No major improvement was achieved in any of the treatments and the patient died. Autopsy confirmed a large heterogeneous thrombotic mass in the pulmonary trunk folding to the right main artery. Additional histological analysis revealed a high fibrin-rich content in the peripheral surroundings of the thrombus. In the case, it was confirmed that the outcome of PMT was directly influenced by mechanical and histological features of the thromboembolus in high-risk PE. Formation of a rather complex thromboembolus

  10. Mechanical Thrombectomy in Acute Ischemic Stroke: Initial Single-Center Experience and Comparison with Randomized Controlled Trials.

    PubMed

    Carvalho, Andreia; Cunha, André; Rodrigues, Marta; Figueiredo, Sofia; Paredes, Ludovina; Gregório, Tiago; Morais, Hugo; Pinheiro, Joaquim; Cruz, Vítor Tedim; Roriz, José Mário; Pinho, João; Ferreira, Carla; Torre, Edgar; Nunes, Joana; Castro, Sérgio; Ribeiro, Manuel; Veloso, Miguel; Barros, Pedro

    2017-03-01

    Until recently, intravenous thrombolysis was the only reperfusion therapy with proven efficacy in patients with acute ischemic stroke. However, this treatment option has low recanalization rates in large-vessel occlusions. The search for additional treatments continued until 5 randomized trials (MR CLEAN, ESCAPE, EXTEND-IA, SWIFT PRIME, and REVASCAT) revealed the superiority of mechanical thrombectomy for anterior circulation large-vessel occlusion. After 1 year of performing thrombectomy with stent retrievers in our tertiary hospital, we intended to answer the question: is it possible to achieve similar results in a "real-world" setting? We analyzed data from our prospective observational registry, compared it with the trials aforementioned, and concluded that the answer is affirmative. Our study population of 77 patients, with a mean age of 68,2 years and 48,1% men, is comparable with these trials in much of selection criteria, baseline characteristics, and rate of previous intravenous thrombolysis (72,7%). Recovery of functional independence at 90 days was achieved in almost two thirds of patients, similarly to the referred trials. We devoted special emphasis on fast recanalization, keeping a simple image selection protocol (based on non-enhanced and computed tomography angiography) and not waiting for clinical response to thrombolysis in patients eligible for mechanical thrombectomy. We emphasize a successful recanalization rate of 87% and only 2,6% symptomatic intracranial hemorrhage. In summary, mechanical thrombectomy seems to be a safe and effective treatment option in a "real-world" scenario, with results similar to those of the recent randomized controlled trials. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  11. Vessel Wall Enhancement and Blood-Cerebrospinal Fluid Barrier Disruption After Mechanical Thrombectomy in Acute Ischemic Stroke.

    PubMed

    Renú, Arturo; Laredo, Carlos; Lopez-Rueda, Antonio; Llull, Laura; Tudela, Raúl; San-Roman, Luis; Urra, Xabier; Blasco, Jordi; Macho, Juan; Oleaga, Laura; Chamorro, Angel; Amaro, Sergio

    2017-03-01

    Less than half of acute ischemic stroke patients treated with mechanical thrombectomy obtain permanent clinical benefits. Consequently, there is an urgent need to identify mechanisms implicated in the limited efficacy of early reperfusion. We evaluated the predictors and prognostic significance of vessel wall permeability impairment and its association with blood-cerebrospinal fluid barrier (BCSFB) disruption after acute stroke treated with thrombectomy. A prospective cohort of acute stroke patients treated with stent retrievers was analyzed. Vessel wall permeability impairment was identified as gadolinium vessel wall enhancement (GVE) in a 24- to 48-hour follow-up contrast-enhanced magnetic resonance imaging, and severe BCSFB disruption was defined as subarachnoid hemorrhage or gadolinium sulcal enhancement (present across >10 slices). Infarct volume was evaluated in follow-up magnetic resonance imaging, and clinical outcome was evaluated with the modified Rankin Scale at day 90. A total of 60 patients (median National Institutes of Health Stroke Scale score, 18) were analyzed, of whom 28 (47%) received intravenous alteplase before mechanical thrombectomy. Overall, 34 (57%) patients had GVE and 27 (45%) had severe BCSFB disruption. GVE was significantly associated with alteplase use before thrombectomy and with more stent retriever passes, along with the presence of severe BCSFB disruption. GVE was associated with poor clinical outcome, and both GVE and severe BCSFB disruption were associated with increased final infarct volume. These findings may support the clinical relevance of direct vessel damage and BCSFB disruption after acute stroke and reinforce the need for further improvements in reperfusion strategies. Further validation in larger cohorts of patients is warranted. © 2017 American Heart Association, Inc.

  12. Acute Pancreatitis after Percutaneous Mechanical Thrombectomy: Case Report and Review of the Literature

    SciTech Connect

    Hershberger, Richard C. Bornak, Arash; Aulivola, Bernadette; Mannava, Krishna

    2011-02-15

    Purpose: We describe a case of severe acute pancreatitis after percutaneous mechanical thrombectomy (PMT) and review the literature for the occurrence of this complication. Materials and Methods: A 53-year-old man with a history of bilateral external iliac artery stent placement sought care for acute onset of lifestyle-limiting left claudication. Angiography confirmed left external iliac stent occlusion, and PMT with the AngioJet Xpeedior catheter (Possis Medical, Minneapolis MN) was performed. Results: After PMT of the occluded external iliac artery, a residual in-stent stenosis required the placement of a second iliac stent. The procedure was complicated by severe acute pancreatitis. Other causes of pancreatitis were eliminated during the patient's hospital stay. A literature review revealed nine cases of acute pancreatitis after PMT. Conclusion: Although rare, pancreatitis can be a devastating complication of PMT. The development of pancreatitis seems to be related to the products of extensive hemolysis triggering an inflammatory process. To prevent this complication, we recommend that close attention be paid to the duration and extent of PMT, thereby avoiding extensive hemolysis and subsequent complications.

  13. Improvement of Stent Retriever Design and Efficacy of Mechanical Thrombectomy in a Flow Model

    SciTech Connect

    Wenger, Katharina; Nagl, Frank; Wagner, Marlies Berkefeld, Joachim

    2013-02-15

    In vitro experiments were performed to evaluate the efficacy of mechanical intracranial thrombectomy comparing the newly developed Aperio stent retriever and standard devices for stroke treatment. The Aperio (A), with an increased working length of 4 cm and a special cell design for capturing and withholding clots, was compared to three benchmark devices: the Solitaire retrievable stent (B), the Merci X6 (C), and the Merci L5 retriever (D). In a vascular glass model with pulsatile flow, reminiscent of the M1 segment of the middle cerebral artery, we repeatedly induced occlusion by generating thrombi via a modified Chandler loop system. The numbers of recanalization attempts, peripheral embolizations, and recanalizations at the site of occlusion were recorded during 10 retrieval experiments with each device. Eleven devices were able to remove the blood clots from the occluded branch. In 34 of 40 experiments, restoration of flow was obtained in 1-3 attempts. The main differences between the study devices were observed in terms of clot withholding and fragmentation during retrieval. Although there was only one fragmentation recorded for device A, disengagement of the whole clot or peripheral embolization of fragments occurred more frequently (5-7 times) with devices B, C, and D. In a vascular model, the design of device A was best at capturing and withholding thrombi during retrieval. Further study will be necessary to see whether this holds true in clinical applications.

  14. Mechanical endovascular thrombectomy for acute ischemic stroke: a retrospective multicenter study in Belgium.

    PubMed

    Fockaert, Niels; Coninckx, Marieke; Heye, Sam; Defreyne, Luc; Brisbois, Denis; Goffette, Pierre; Gralla, Jan; Mordasini, Pasquale; Peeters, Andre; Desfontaines, Philippe; Hemelsoet, Dimitri; Thijs, Vincent; Lemmens, Robin

    2016-03-01

    Clinical trials have shown a beneficial effect of mechanical thrombectomy in acute ischemic stroke patients treated within six up to even 12 h after symptom onset. This treatment was already performed in selected hospitals in Belgium before completion of the randomized controlled trials. Outcome data on these procedures in Belgium have not been published. We performed a retrospective multicenter study of all patients with acute ischemic stroke treated with mechanical endovascular therapy in four hospitals in Belgium. Clinical outcomes, as measured by the modified Rankin Scale (mRS), site of arterial occlusion, reperfusion and the association between these variables were studied. The study included 80 patients: 65 patients with an occlusion in the anterior circulation and 15 with an occlusion in the posterior circulation. Good functional outcome (GFO) rates, defined as mRS 0-2 at 90 days, were 42 % in all patients, 44 % in anterior circulation stroke and 34 % in posterior circulation stroke. Reperfusion was achieved in 78 % of patients; more (100 %) in patients with posterior compared to patients with anterior circulation stroke (72 %; p = 0.02). The rate of GFO was greater in patients with reperfusion versus patients in whom reperfusion was not achieved (adjusted OR 8.2, 95 % CI 2.0-34.2). Symptomatic intracerebral hemorrhage was documented in 5 % of all patients. Endovascular treatment with mechanical devices for acute ischemic stroke in Belgium results in GFO and reperfusion rates similar to recently published results in the endovascular-treated arms of randomized clinical trials. Rates of symptomatic intracranial hemorrhage are low and comparable to other cohort studies and clinical trials.

  15. Development of a recalcitrant, large clot burden, bifurcation occlusion model for mechanical thrombectomy.

    PubMed

    Srinivasan, Visish M; Chen, Stephen R; Camstra, Kevin M; Chintalapani, Gouthami; Kan, Peter

    2017-04-01

    OBJECTIVE Stroke is a major cause of disability and death in adults. Several large randomized clinical trials have shown the significant benefit of mechanical thrombectomy with modern stent retrievers in the treatment of large-vessel occlusions. However, large clots located at bifurcations remain challenging to treat. An in vivo model of these recalcitrant clots needs to be developed to test future generations of devices. METHODS Autologous blood was drawn from anesthetized swine via a femoral sheath. Blood was then mixed with thrombin, calcium chloride, and saline, and injected into silicone tubing to form cylindrical clots in the standard fashion. Matured clots were then delivered in an unfragmented fashion directly into the distal extracranial vasculature, at branch points where vessel sizes mimic the human middle cerebral artery, by using Penumbra aspiration tubing and the Penumbra ACE68 reperfusion catheter. RESULTS A total of 5 adult swine were used to develop the model. The techniques evolved during experiments in the first 3 animals, and the last 2 were used to establish the final model. In these 2 swine, a total of 8 autologous clots, 15-20 mm, were injected directly into 8 distal extracranial vessels at branch points to mimic a bifurcation occlusion in a human. All clots were delivered directly at a distal bifurcation or trifurcation in an unfragmented fashion to cause an occlusion. Ten revascularization attempts were made, and none of the branch-point occlusions were fully revascularized on the first attempt. CONCLUSIONS Using novel large-bore distal access catheters, large unfragmented clots can be delivered into distal extracranial vessels in a swine occlusion model. The model mimics the clinical situation of a recalcitrant bifurcation occlusion and will be valuable in the study of next-generation stroke devices and in training settings.

  16. Aspiration catheter for percutaneous thrombectomy: clinical results.

    PubMed

    Guenther, R W; Vorwerk, D

    1990-04-01

    The clinical application of an aspiration thrombectomy system is presented. The system consists of a 7-F Teflon catheter with a rotating coaxial propeller-tipped wire. Thrombectomy was successful in treating occlusion of two femoropopliteal arteries and one hemodialysis implant but was not completely successful in a draining shunt vein. Preliminary results are encouraging; mechanical thrombectomy may offer an alternative to local lysis therapy.

  17. Uric acid therapy improves the outcomes of stroke patients treated with intravenous tissue plasminogen activator and mechanical thrombectomy.

    PubMed

    Chamorro, Ángel; Amaro, Sergio; Castellanos, Mar; Gomis, Meritxell; Urra, Xabier; Blasco, Jordi; Arenillas, Juan F; Román, Luis S; Muñoz, Roberto; Macho, Juan; Cánovas, David; Marti-Fabregas, Joan; Leira, Enrique C; Planas, Anna M

    2017-06-01

    Background Numerous neuroprotective drugs have failed to show benefit in the treatment of acute ischemic stroke, making the search for new treatments imperative. Uric acid is an endogenous antioxidant making it a drug candidate to improve stroke outcomes. Aim To report the effects of uric acid therapy in stroke patients receiving intravenous thrombolysis and mechanical thrombectomy. Methods Forty-five patients with proximal vessel occlusions enrolled in the URICO-ICTUS trial received intravenous recombinant tissue plasminogen activator within 4.5 h after stroke onset and randomized to intravenous 1000 mg uric acid or placebo (NCT00860366). These patients also received mechanical thrombectomy because a brain computed tomogaphy angiography confirmed the lack of proximal recanalization at the end of systemic thrombolysis. The primary outcome was good functional outcome at 90 days (modified Rankin Score 0-2). Safety outcomes included mortality, symptomatic intracerebral bleeding, and gout attacks. Results The rate of successful revascularization was >80% in the uric acid and the placebo groups but good functional outcome was observed in 16 out of 24 (67%) patients treated with uric acid and 10 out of 21 (48%) treated with placebo (adjusted Odds Ratio, 6.12 (95% CI 1.08-34.56)). Mortality was observed in two out of 24 (8.3%) patients treated with uric acid and one out of 21 (4.8%) treated with placebo (adjusted Odds Ratio, 3.74 (95% CI 0.06-226.29)). Symptomatic cerebral bleeding and gout attacks were similar in both groups. Conclusions Uric acid therapy was safe and improved stroke outcomes in stroke patients receiving intravenous thrombolysis followed by thrombectomy. Validation of this simple strategy in a larger trial is urgent.

  18. Acute thromboembolic occlusion of the superior mesenteric artery following covered stent occlusion in the superior mesenteric artery: endovascular therapy using mechanical rotational thrombectomy.

    PubMed

    Goltz, Jan P; Petritsch, Bernhard; Spor, Leo; Hahn, Dietbert; Kickuth, Ralph

    2012-09-01

    Acute thromboembolic occlusion of the superior mesenteric artery is a rare and often fatal condition in which surgery represents the golden standard in therapy. We present a case in which a patient was treated with covered stent implantation for acute bleeding from the superior mesenteric artery following pancreatic resection, radiation, and embolization of a hepatic artery pseudoaneurysm. Some weeks later clinical signs were suggestive of acute thromboembolic occlusion of the superior mesenteric artery and digital subtraction angiography showed occlusion of the previously implanted covered stents. The patient was successfully treated transfemorally with percutaneous mechanical instent thrombectomy using a 6F Rotarex® catheter. We conclude that in selected cases percutaneous mechanical thrombectomy may represent a minimally-invasive alternative to open surgical thrombectomy for treatment of acute thromboembolic occlusion of the superior mesenteric artery.

  19. Increased risk of renal dysfunction with percutaneous mechanical thrombectomy compared with catheter-directed thrombolysis.

    PubMed

    Morrow, Katherine L; Kim, Ann H; Plato, Steven A; Shevitz, Andrew J; Goldstone, Jerry; Baele, Henry; Kashyap, Vikram S

    2017-05-01

    Percutaneous mechanical thrombectomy (PMT) is regularly used in the treatment of both venous and arterial thrombosis. Although there has been no formal report, PMT has been linked to cases of reversible postoperative acute kidney injury (AKI). The purpose of this study is to evaluate the risk of renal dysfunction in patients undergoing PMT vs catheter-directed thrombolysis (CDT) for treatment of an acute thrombus. This study is a retrospective review of all patients in a single institution with a Current Procedural Terminology code for PMT or CDT from January 2009 through December 2014. Each patient was grouped into one of the four following procedural categories: PMT only, PMT with tissue plasminogen activator (tPA) pulse-spray, PMT with CDT, or CDT only. Preoperative and postoperative creatinine and glomerular filtration rate (GFR) values were obtained for each patient. The RIFLE (Risk, Injury, Failure, Loss, and End-stage renal disease) criteria were used to categorize the extent of renal dysfunction. χ(2) analysis, one-way analysis of variance, and unpaired t-test were used to assess significance. A total of 227 patients were reviewed, of which 82 were excluded due to either existence of preoperative AKI, history of end-stage renal disease, or lack of clinical data. Of the remaining 145 patients, 53 (37%) presented with arterial thrombosis (mean age, 62 years; 43% male) and 92 (63%) presented with venous thrombosis (mean age, 48 years; 45% male). The incidence of renal dysfunction was highest in the PMT/tPA pulse group (21%), followed by the PMT group (20%) and the PMT/CDT group (14%). CDT was not associated with renal dysfunction. PMT (P = .046), and PMT/tPA pulse (P = .033) were associated with higher rates of renal dysfunction than the CDT controls. The average preoperative GFR for the 22 patients who developed AKI was 53.7 ± 9.4 mL/min/1.73 m(2). The minimum postoperative GFR within 48 hours was an average of 35 ± 16 mL/min/1.73 m(2

  20. Mechanical thrombectomy in patients with medical contraindications for intravenous thrombolysis: a prospective observational study.

    PubMed

    Alonso de Leciñana, María; Martínez-Sánchez, Patricia; García-Pastor, Andrés; Kawiorski, Michal M; Calleja, Patricia; Sanz-Cuesta, Borja E; Díaz-Otero, Fernando; Frutos, Remedios; Sierra-Hidalgo, Fernando; Ruiz-Ares, Gerardo; Fandiño, Eduardo; Díez-Tejedor, Exuperio; Gil-Nuñez, Antonio; Fuentes, Blanca

    2016-11-07

    The present study was conducted with the objective of evaluating the safety of primary mechanical thrombectomy (MT) in patients with large vessel occlusion (LVO) stroke and comorbidities that preclude treatment with IV thrombolysis (IVT), compared with patients who received standard IVT treatment followed by MT. Secondary objectives were to analyse the recanalization rate and outcomes. A prospective observational multicenter study (FUN-TPA) that recruited patients treated within 4.5 hours of symptom onset was performed. Treatments were IVT followed by MT if occlusion persisted, or primary MT when IVT was contraindicated. Outcome measures were procedural complications, symptomatic intracranial hemorrhage (SICH), recanalization rate, National Institutes of Health Stroke Scale (NIHSS) score at 7 days, modified Rankin Scale (mRS) score and mortality at 90 days. Of 131 patients, 21 (16%) had medical contraindications for IVT and were treated primarily with MT whereas 110 (84%) underwent IVT, followed by MT in 53 cases (40%). The recanalization rate and procedural complications were similar in the two groups. There were no SICHs after primary MT vs 3 (6%) after IVT+MT. Nine patients (43%) in the primary MT group achieved independence (mRS 0-2) compared with 36 (68%) in the IVT+MT group (p=0.046). Mortality rates in the two groups were 14% (n=3) vs 4% (n=2) (p=0.13). Adjusted ORs for independence in patients receiving standard IVT+MT vs MT in patients with medical contraindications for IVT were 2.8 (95% CI 0.99 to 7.98) and 0.24 (95% CI 0.04 to 1.52) for mortality. MT is safe in patients with potential comorbidity-derived risks that preclude IVT. MT should be offered, aiming for prompt recanalization, to patients with LVO stroke unsuitable for IVT. NCT02164357; Results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  1. Mechanical Thrombectomy in Wake-Up Strokes: A Case Series Using Alberta Stroke Program Early CT Score (ASPECTS) for Patient Selection.

    PubMed

    Konstas, Angelos Aristeidis; Minaeian, Artin; Ross, Ian B

    2017-07-01

    There is lack of published studies on mechanical thrombectomy with stent retrievers for wake-up stroke (WUS). To report the outcomes of WUS patients with large vessel occlusions, selected for intervention based on Alberta Stroke Program Early CT Score (ASPECTS) and treated with stent retrievers or primary aspiration thrombectomy. Data were collected retrospectively for each consecutive WUS patient undergoing mechanical thrombectomy with a stent retriever or primary aspiration catheter between February 2015 and September 2016. ASPECTS ≥ 6 was used as the primary imaging criterion for offering thrombectomy in these WUS patients. Main outcomes were the in-hospital improvement in the National Institutes of Health Stroke Scale (NIHSS) and the occurrence of symptomatic hemorrhage. Twelve patients were included in this study; 11 were treated with stent retrievers and 1 was treated with primary aspiration thrombectomy alone. Successful recanalization was achieved in 100% of the patients (33% thrombolysis in cerebral infarction [TICI] 2B and 67% TICI 3). Every patient experienced a reduction in the NIHSS during hospitalization, with a mean NIHSS decrease of 11.1 ± 5.1 points. There was a trend for a larger reduction in the NIHSS in patients with TICI 3 compared to TICI 2B recanalization. There was no symptomatic intracranial hemorrhage in our cohort. For patients with WUS, careful selection of patients using ASPECTS may allow for safe interventions, with low risk of clinical deterioration, and no-periprocedural mortality. All our patients demonstrated a reduction in their NIHSS after the thrombectomy and clinical improvement. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  2. Endovascular mechanical thrombectomy of an occluded superior division branch of the left MCA for acute cardioembolic stroke.

    PubMed

    Schumacher, H C; Meyers, P M; Yavagal, D R; Harel, N Y; Elkind, M S V; Mohr, J P; Pile-Spellman, J

    2003-01-01

    Cardiac embolism accounts for a large proportion of ischemic stroke. Revascularization using systemic or intra-arterial thrombolysis is associated with increasing risks of cerebral hemorrhage as time passes from stroke onset. We report successful mechanical thrombectomy from a distal branch of the middle cerebral artery (MCA) using a novel technique. A 72-year old man suffered an acute ischemic stroke from an echocardiographically proven ventricular thrombus due to a recent myocardial infarction. Intraarterial administration of 4 mg rt-PA initiated at 5.7 hours post-ictus failed to recanalize an occluded superior division branch of the left MCA. At 6 hours, symptomatic embolic occlusion persisted. Mechanical extraction of the clot using an Attracter-18 device (Target Therapeutics, Freemont, CA) resulted in immediate recanalization of the MCA branch. Attracter-18 for acute occlusion of MCA branches may be considered in selected patients who fail conventional thrombolysis or are nearing closure of the therapeutic window for use of thrombolytic agents.

  3. [Mechanical thrombectomy with the Solitaire AB device in acute ischemic stroke of posterior circulation: a series of 17 cases].

    PubMed

    He, Zijun; Luo, Yongchun; Zhang, Zhenhai; Liang, Chunyang; Wang, Bin; Zhang, Qiang; Xu, Ruxiang; Shen, Chunsen

    2016-05-01

    To evaluate the efficacy and safety of mechanical thrombectomy with the Solitaire AB device in recanalization of patients with acute ischemic stroke of posterior circulation. The clinical data of 17 consecutive patients with acute ischemic stroke of posterior circulation, treated with the Solitaire AB device from August 2011 to August 2015 in Department of Neurosurgery, the Military General Hospital of Beijing People's Liberation Army, were extracted and then retrospectively analyzed. There were 12 male and 5 female patients with a median age of 60 years (ranging from 44 to 75 years). Among them, 8 cases occluded in basilar artery, 4 cases occluded in vertebral artery and 5 cases occluded in vertebral plus basilar artery. Recanalization rate as well as complications after treatment were analysized. Also, neurological functions of the patients before and after treatment, measured by National Institute of Health stroke scale (NIHSS) score, were compared via t test and the clinical outcomes were assessed by modified Rankin score (mRS) at 90 days after treatment. Fifteen patients resulted in successfully recanalization, and 2 cases failed both of whose onset to sheath time were above 7.5 hours. The NIHSS score at 7 days was 11±10, which was significantly decreased compared to the admission NIHSS score 17±5 (t=2.949, P=0.009). No symptomatic intracranial hemorrhage case was found after thrombectomy. At 90 days, one patient died(mRS 6), one patient seriously disabled (mRS 5), two patients moderately seriously disabled (mRS 4), four patients resulted in moderate outcome (mRS 3) and the other 9 patients achieved good outcome (mRS 0 to 2). The dead and seriously disabled cases were both due to failure in recanalization. Two moderately seriously disabled cases were probably attributed to their severe admission condition (NIHSS >20) and prolonged time (onset to sheath time >6 hours). Mechanical thrombectomy with the Solitaire AB device contributes to a high rate of

  4. Efficacy of Balloon-Guiding Catheter for Mechanical Thrombectomy in Patients with Anterior Circulation Ischemic Stroke

    PubMed Central

    Oh, Jae-Sang; Yoon, Seok-Mann; Shim, Jai-Joon; Doh, Jae-Won; Bae, Hack-Gun; Lee, Kyeong-Seok

    2017-01-01

    Objective To evaluate the efficacy of balloon guiding catheter (BGC) during thrombectomy in anterior circulation ischemic stroke. Methods Sixty-two patients with acute anterior circulation ischemic stroke were treated with thrombectomy using a Solitaire stent from 2011 to 2016. Patients were divided into the BGC group (n=24, 39%) and the non-BGC group (n=38, 61%). The number of retrievals, procedure time, thrombolysis in cerebral infarction (TICI) grade, presence of distal emboli, and clinical outcomes at 3 months were evaluated. Results Successful recanalization was more frequent in BGC than in non-BGC (83% vs. 66%, p=0.13). Distal emboli occurred less in BGC than in non-BGC (23.1% vs. 57.1%, p=0.02). Good clinical outcome was more frequent in BGC than in non-BGC (50% vs. 16%, p=0.03). The multivariate analysis showed that use of BGC was the only independent predictor of good clinical outcome (odds ratio, 5.19: 95% confidence interval, 1.07–25.11). More patients in BGC were successfully recanalized in internal carotid artery (ICA) occlusion with small retrieval numbers (<3) than those in non-BGC (70% vs. 24%, p=0.005). In successfully recanalized ICA occlusion, distal emboli did not occur in BGC, whereas nine patients had distal emboli in non-BGC (0% vs. 75%, p=0.001) and good clinical outcome was superior in BGC than in non-BGC (55.6% vs. 8.3%, p=0.01). Conclusion A BGC significantly reduces the number of retrievals and the occurrence of distal emboli, thereby resulting in better clinical outcomes in patients with anterior circulation ischemic stroke, particularly with ICA occlusion. PMID:28264235

  5. Initial clinical use of a novel mechanical thrombectomy device, XCOIL™, in hemodialysis graft and fistula declot procedures

    PubMed Central

    Monsky, Wayne L.; Latchaw, Richard E.

    2016-01-01

    PURPOSE We aimed to evaluate the safety and effectiveness of a novel catheter-based mechanical thrombectomy device, XCOIL™, as a first line therapy to restore patency of thrombosed dialysis grafts and fistulae. METHODS In 2010, 18 consecutive/sequential patients (11 male, 7 female; median age, 52 years; age range, 32–69 years) with occluded arteriovenous grafts (n=15) or fistulae (n=3) were treated with XCOIL™ (NexGen Medical Systems Inc.) without adjunctive thrombolytic drugs. XCOIL™ was advanced distal to the thrombus within the outflow vein as well as distal to the arterial inflow platelet thrombin plug, using a 4F angiographic catheter. The percentage of thrombus cleared, primary patency, procedure time, and XCOIL™ performance were documented. RESULTS Thrombosis occurred 1–30 days prior to the procedure. Thrombosed segments of graft/fistula measured 10–50 cm. Pre- and postprocedure angiography demonstrated that in 15 of 18 cases (83%) XCOIL™ removed 80%–100% of the venous outflow thrombus. In 11 of 14 cases (79%), the platelet thrombin plug was also removed. Thrombectomy procedure time averaged 8 min, with one to three passes with the XCOIL™ required. No evidence of distal embolization or graft/vessel injury was found on angiography following clot removal. In four cases in whom patency was not restored with XCOIL™, subsequent use of other clot removal devices also failed to restore patency. In one case with severe venous stenosis, the device failed to deploy and the thrombus was not captured. No intraprocedural complications related to XCOIL™ use occurred. CONCLUSION XCOIL™ is an effective and safe first-line therapy option for the treatment of thrombosed hemodialysis grafts/fistulae. Rapid removal of intact thrombus and platelet thrombin plug can be achieved without adjunctive thrombolytics. PMID:27015445

  6. A Comparison between Mechanical Thrombectomy and Intra-arterial Fibrinolysis in Acute Basilar Artery Occlusion: Single Center Experiences

    PubMed Central

    Jung, Seunguk; Jung, Cheolkyu; Bae, Yun Jung; Choi, Byung Se; Kim, Jae Hyoung; Lee, Sang-Hwa; Chang, Jun Young; Kim, Beom Joon; Han, Moon-Ku; Bae, Hee-Joon; Kwon, Bae Ju; Cha, Sang-Hoon

    2016-01-01

    Background and Purpose Recent advances in intra-arterial techniques and thrombectomy devices lead to high rate of recanalization. However, little is known regarding the effect of the evolvement of endovascular revascularization therapy (ERT) in acute basilar artery occlusion (BAO). We compared the outcome of endovascular mechanical thrombectomy (EMT) versus intra-arterial fibrinolysis (IAF)-based ERT in patients with acute BAO. Methods After retrospectively reviewed a registry of consecutive patients with acute ischemic stroke who underwent ERT from September 2003 to February 2015, 57 patients with acute BAO within 12 hours from stroke onset were enrolled. They were categorized as an IAF group (n=24) and EMT group (n=33) according to the primary technical option. We compared the procedural and clinical outcomes between the groups. Results The time from groin puncture to recanalization was significantly shorter in the EMT group than in the IAF group (48.5 [25.3 to 87.8] vs. 92 [44 to 179] minutes; P=0.02) The rate of complete recanalization was significantly higher in the EMT group than in the IAF group (87.9% vs 41.7%; P<0.01). The good outcome of the modified Rankin Scale score≤2 at 3 months was more frequent in the EMT group than in the IAF group, but it was not statistically significant (39.4% vs 16.7%; P=0.06). Conclusions EMT-based ERT in patients with acute BAO is superior to IAF-based ERT in terms of the reduction of time from groin puncture to recanalization and the improvement of the rate of complete recanalization. PMID:27283281

  7. Assessment of factors associated with prominent changes in blood pressure during an early mobilization protocol for patients with acute ischemic stroke after mechanical thrombectomy

    PubMed Central

    YAGI, Maiko; WATANABE, Sato; KONDO, Chika; KAIHOKO, Yukiko; ENDO, Koji; MIYASHITA, Fumio; TAKADA, Tatsuro; UEDA, Toshihiro

    2016-01-01

    Objective: To assess factors associated with changes in blood pressure during early mobilization protocol for patients with acute ischemic stroke who were treated with mechanical thrombectomy. Design: Retrospective observational study. Method: We analyzed patients with acute ischemic stroke who were treated with mechanical thrombectomy (MT group, n=60) and patients who received conservative medical management (control group, n=60) matched by age and National Institute Health of Stroke Score at admission from April 2009 to July 2014. The proportion of patients with prominent blood pressure change during an early mobilization protocol was compared between the MT group and control group. Factors associated with prominent blood pressure change were also analyzed using multivariable logistic regression analysis. Result: The deviation in blood pressure response was much more significant in the MT than control group (13.3 vs. 1.7%, p<0.016). Logistic regression analysis showed the interval from admission to being able to sit in a wheelchair associated with prominent changes in blood pressure (odds ratio, 1.604; 95% confidence interval, 1.196-2.150; p<0.002). Conclusion: Our results showed that prominent changes in blood pressure during an early mobilization protocol can occur easily in patients with acute ischemic stroke after mechanical thrombectomy. PMID:28289575

  8. Eligibility for mechanical thrombectomy in acute ischemic stroke: A phase IV multi-center screening log registry.

    PubMed

    Tsivgoulis, Georgios; Goyal, Nitin; Mikulik, Robert; Sharma, Vijay K; Katsanos, Aristeidis H; Zand, Ramin; Paliwal, Prakash R; Roussopoulou, Andromachi; Volny, Ondrej; Pandhi, Abhi; Zompola, Christina; Elijovich, Lucas; Safouris, Apostolos; Chang, Jason; Alexandrov, Andrei V; Alexandrov, Anne W

    2016-12-15

    No eligibility screening logs were kept in recent mechanical thrombectomy (MT) RCTs establishing safety and efficacy of endovascular reperfusion therapies for acute ischemic stroke (AIS). We sought to evaluate the potential eligibility for MT among consecutive AIS patients in a prospective international multicenter study. We prospectively evaluated consecutive AIS patients admitted in four tertiary-care stroke centers during a twelve-month period. Potential eligibility for MT was evaluated using inclusion criteria from MR CLEAN & REVASCAT. Our study population consisted of 1464 AIS patients (mean age 67±14years, 56% men, median admission NIHSS-score: 5, IQR: 3-10). A total of 123 (8%, 95% CI: 7%-10%) and 82 (6%, 95% CI: 5%-7%) patients fulfilled the inclusion criteria for MR CLEAN&REVASCAT respectively. No evidence of heterogeneity (p>0.100) was found in the eligibility for MT across the participating centers. Absence of proximal intracranial occlusion (69%) and hospital arrival outside the eligible time window (38% for MR CLEAN & 35% for REVASCAT) were the two most common reasons for ineligibility for MT. Our everyday clinical practice experience suggests that approximately one out of thirteen to seventeen consecutive AIS may be eligible for MT if inclusion criteria for MR CLEAN and REVASCAT are strictly adhered to.

  9. Endovascular Stroke Therapy Focused on Stent Retriever Thrombectomy and Direct Clot Aspiration: Historical Review and Modern Application

    PubMed Central

    Kang, Dong-Hun; Park, Jaechan

    2017-01-01

    Intravenous recombinant tissue plasminogen activator had been the only approved treatment for acute ischemic stroke since its approval in 1995. However, the restrictive time window, numerous contraindications, and its low recanalization rate were all limitations of this modality. Under those circumstances, endovascular stroke therapy went through a great evolution during the past two decades of intravenous thrombolysis. The results of the 2013 randomized trials for endovascular stroke therapy were neutral, although they were limited by insufficient imaging screening at enrollment, early-generation devices with less efficacy, and treatment delays. Huge progress was made in 2015, as there were five randomized clinical trials which all demonstrated the safety and efficacy of endovascular stroke treatment. Despite differences in detail patient enrollment criteria, all 5 trials employed key factors for good functional recovery; (1) screening with non-invasive imaging to identify the proximal occlusion and exclude a large infarct core, (2) using highly effective modern thrombectomy devices mainly with stent retriever, and (3) establishment of a fast workflow to achieve effective reperfusion. The results of those trials indicate that modern thrombectomy devices can allow for faster and more effective reperfusion, which can lead to improved clinical outcomes compared to intravenous thrombolysis alone. These advances in mechanical thrombectomy are promising in the global fight against ischemic stroke-related disability and mortality. Two current mainstreams among such mechanical thrombectomy techniques, “stent retriever thrombectomy” and “direct clot aspiration”, are the topic of this review. Stent retriever thrombectomy using Solitaire and Trevo retriever will be firstly discussed. And, the commonalities and the differences between two major clot aspiration thrombectomy techniques; a direct aspiration first pass technique (ADAPT) and forced arterial suction

  10. Forced Arterial Suction Thrombectomy Using Distal Access Catheter in Acute Ischemic Stroke

    PubMed Central

    Lee, Ho-Cheol; Kang, Dong-Hun; Hwang, Yang-Ha; Kim, Yong-Sun

    2017-01-01

    Historical innovations in mechanical thrombectomy devices and strategies for ischemic stroke have resulted in improved angiographic outcomes and better clinical outcomes. Various devices have been used, but the two most common approaches are aspiration thrombectomy and stent-retrieval thrombectomy. Aspiration thrombectomy has advanced from the traditional Penumbra system to forced arterial suction thrombectomy and a direct aspiration first-pass technique. Newer generation aspiration catheters with flexible distal tips and a larger bore have demonstrated faster and better recanalization relative to older devices. Recently, several species of distal access catheters have similar structural characteristics to the Penumbra reperfusion catheter. Therefore, we used the distal access catheter for forced arterial suction thrombectomy in three patients with acute ischemic stroke. In each case, we achieved fast and complete recanalization without significant complications. Forced arterial suction thrombectomy using a distal access catheter might provide another option for mechanical thrombectomy in patients with acute ischemic stroke. PMID:28316869

  11. TREVO and Capture LP have equal technical success rates in mechanical thrombectomy of proximal and distal anterior circulation occlusions.

    PubMed

    Protto, Sara; Pienimäki, Juha-Pekka; Seppänen, Janne; Matkaselkä, Ira; Ollikainen, Jyrki; Numminen, Heikki; Sillanpää, Niko

    2017-07-01

    Mechanical thrombectomy (MT) is a proven method to treat large vessel occlusions in acute anterior circulation stroke. We compared the technical, imaging, and clinical outcomes of MT performed with either TREVO or Capture LP devices. There were 42 and 43 patients in the TREVO and Capture LP groups, respectively. Baseline variables, technical outcome (Thrombolysis In Cerebral Infarction, TICI), 24 hours imaging outcome, and 3-month clinical outcome (modified Rankin Scale, mRS) were prospectively recorded. The patients were stratified according to clot location, groups compared, and logistic regression models devised to study the effect of device selection on the clinical outcome. The technical success rates were equal in both proximal (internal carotid artery and proximal M1 segment) and distal occlusions (distal M1 and M2 segments). The proportion of TICI 2b or 3 was 96% and 87% with TREVO and 87% and 89% with Capture LP (p=0.25 and p=0.80, respectively). Device selection did not significantly predict good clinical outcome (mRS ≤2) in either proximal or distal occlusions. In multivariate analysis, selecting Capture LP borderline significantly increased the odds of an excellent outcome close to sixfold both in proximal and distal occlusions (OR 6.7, 95% CI 0.82 to 53.7, p=0.08 and OR 5.7, 95% CI 0.88 to 37.8, p=0.07, respectively). TREVO and Capture LP perform equally well in proximal and distal occlusions in the anterior circulation when technical and good clinical outcome are considered. Capture LP may have a small advantage in reaching mRS ≤1 at 3 months. However, this needs to be confirmed in a randomized study. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  12. Safety and Efficacy of Mechanical Thrombectomy Using Stent Retrievers in the Endovascular Treatment of Acute Ischaemic Stroke: A Systematic Review

    PubMed Central

    Puñal-Riobóo, Janet; Atienza, Gerardo; Blanco, Miguel

    2015-01-01

    Background The treatment of choice for acute ischaemic stroke is the intravenous administration of recombinant tissue plasminogen activator within 3-4.5 h of symptom onset. However, the use of a thrombolytic would be limited by its narrow therapeutic window and contraindications. As a result, in recent years, techniques such as mechanical thrombectomy have emerged, which employ thrombus retrieval devices, such as stent retrievers (Solitaire™, Trevo® or Revive™), whose safety and efficacy in the endovascular treatment of acute ischaemic stroke is analysed in this article. Methods A systematic literature search was undertaken until March 2015. The quality of evidence was assessed according to the GRADE methodology. A meta-analysis of the results of randomised controlled trials (RCTs) was performed, and the weighted average for the case series' sample size was calculated (Review Manager v5.2 and SPSS v19). Results Seventeen primary studies (2 RCTs, Solitaire™ and Trevo® vs. Merci®, and 15 case series) were selected. The RCT results show that stent retrievers have a safety profile similar to the Merci® device. However, both Solitaire™ and Trevo® achieved a higher recanalisation success rate (OR, 4.56; 95% CI, 2.63-7.90; p < 0.00001) and appropriate clinical outcome at 90 days (OR, 2.54; 95% CI, 1.52-4.25; p < 0.0004), although the 90-day mortality rate was similar in both groups (OR, 0.75; 95% CI, 0.17-3.37; p = 0.70). Conclusions Stent retrievers appear to be safe and effective devices, achieving high recanalisation rates and good clinical outcomes in the endovascular treatment of patients with acute ischaemic stroke due to the occlusion of intracranial arteries in comparison with the clot retriever Merci®. PMID:26279662

  13. Mechanical Thrombectomy Using Solitaire in a 6-Year-Old Child

    PubMed Central

    Huded, Vikram; Kamath, Vikram; Chauhan, Bhumir; de Souza, Romnesh; Nair, Rithesh; Sapare, Anil; Kekatpure, Minal

    2015-01-01

    A six-year-old boy was diagnosed as recurrent posterior circulation stroke secondary to basilar artery occlusion with rapid progression of symptoms. Etiology of stroke was a dissection of V3 segment of left vertebral artery, which was treated using endovascular technique 26 hours after worsening of symptoms. Since the guidelines for acute revascularization in pediatric stroke are not well established, there is limited experience in the use of mechanical devices for acute ischemic stroke revascularization in children. To our knowledge, this is one of the youngest reported cases of acute ischemic stroke from Asia managed with newer mechanical clot removal devices. PMID:26060522

  14. Mechanical thrombectomy in acute ischemic stroke: Consensus statement by ESO-Karolinska Stroke Update 2014/2015, supported by ESO, ESMINT, ESNR and EAN.

    PubMed

    Wahlgren, Nils; Moreira, Tiago; Michel, Patrik; Steiner, Thorsten; Jansen, Olav; Cognard, Christophe; Mattle, Heinrich P; van Zwam, Wim; Holmin, Staffan; Tatlisumak, Turgut; Petersson, Jesper; Caso, Valeria; Hacke, Werner; Mazighi, Mikael; Arnold, Marcel; Fischer, Urs; Szikora, Istvan; Pierot, Laurent; Fiehler, Jens; Gralla, Jan; Fazekas, Franz; Lees, Kennedy R

    2016-01-01

    The original version of this consensus statement on mechanical thrombectomy was approved at the European Stroke Organisation (ESO)-Karolinska Stroke Update conference in Stockholm, 16-18 November 2014. The statement has later, during 2015, been updated with new clinical trials data in accordance with a decision made at the conference. Revisions have been made at a face-to-face meeting during the ESO Winter School in Berne in February, through email exchanges and the final version has then been approved by each society. The recommendations are identical to the original version with evidence level upgraded by 20 February 2015 and confirmed by 15 May 2015. The purpose of the ESO-Karolinska Stroke Update meetings is to provide updates on recent stroke therapy research and to discuss how the results may be implemented into clinical routine. Selected topics are discussed at consensus sessions, for which a consensus statement is prepared and discussed by the participants at the meeting. The statements are advisory to the ESO guidelines committee. This consensus statement includes recommendations on mechanical thrombectomy after acute stroke. The statement is supported by ESO, European Society of Minimally Invasive Neurological Therapy (ESMINT), European Society of Neuroradiology (ESNR), and European Academy of Neurology (EAN). © 2016 World Stroke Organization.

  15. Implications of limiting mechanical thrombectomy to patients with emergent large vessel occlusion meeting top tier evidence criteria.

    PubMed

    Bhole, Rohini; Goyal, Nitin; Nearing, Katherine; Belayev, Andrey; Doss, Vinodh T; Elijovich, Lucas; Hoit, Daniel A; Tsivgoulis, Georgios; Alexandrov, Andrei V; Arthur, Adam S; Alexandrov, Anne W

    2017-03-01

    Recent guidelines for endovascular management of emergent large vessel occlusion (ELVO) award top tier evidence to the same selective criteria in recent trials. We aimed to understand how guideline adherence would have impacted treatment numbers and outcomes in a cohort of patients from a comprehensive stroke center. A retrospective observational study was conducted using consecutive emergent endovascular patients. Mechanical thrombectomy (MT) was performed with stent retrievers or large bore clot aspiration catheters. Procedural outcomes were compared between patients meeting, and those failing to meet, top tier evidence criteria. 126 patients receiving MT from January 2012 to June 2015 were included (age 31-89 years, National Institutes of Health Stroke Scale (NIHSS) score 2-38); 62 (49%) patients would have been excluded if top tier criteria were upheld: pretreatment NIHSS score <6 (10%), Alberta Stroke Program Early CT score <6 (6.5%), premorbid modified Rankin Scale (mRS) score ≥2 (27%), M2 occlusion (10%), posterior circulation (32%), symptom to groin puncture >360 min (58%). 26 (42%) subjects had more than one top tier exclusion. Symptomatic intracerebral hemorrhage (sICH) and systemic hemorrhage rates were similar between the groups. 3 month mortality was 45% in those lacking top tier evidence compared with 26% (p=0.044), and 3 month mRS score 0-2 was 33% versus 46%, respectively (NS). After adjusting for potential confounders, top tier treatment was not associated with neurological improvement during hospitalization (β -8.2; 95% CI -24.6 to -8.2; p=0.321), 3 month mortality (OR=0.38; 95% CI 0.08 to 1.41), or 3 month favorable mRS (OR=0.97; 95% CI 0.28 to 3.35). Our study showed that with strict adherence to top tier evidence criteria, half of patients may not be considered for MT. Our data indicate no increased risk of sICH and a potentially higher mortality that is largely due to treatment of patients with basilar occlusions and those treated at

  16. National trends in utilization and outcomes of endovascular treatment of acute ischemic stroke patients in the mechanical thrombectomy era.

    PubMed

    Hassan, Ameer E; Chaudhry, Saqib A; Grigoryan, Mikayel; Tekle, Wondwossen G; Qureshi, Adnan I

    2012-11-01

    Because several new devices for mechanical thrombectomy have become available, the outcomes of patients undergoing endovascular treatment for acute ischemic stroke are expected to improve in the United States. We performed this analysis to evaluate trends in utilization of endovascular treatment and associated rates of death and disability among acute ischemic stroke patients over a 6-year period, including further assessment within age strata. We obtained data for patients admitted to hospitals in the United States from 2004 to 2009 with a primary diagnosis of ischemic stroke using a large national database. We determined the rate and pattern of utilization, and associated in-hospital outcomes of endovascular treatment among ischemic stroke patients and further analyzed trends within age strata. Outcomes were classified as minimal disability, moderate to severe disability, and death based on discharge disposition and compared between 2 time periods: 2004 to 2007 (post-MERCI) and 2008 to 2009 (post-Penumbra) approvals Of the 3,292,842 patients admitted with ischemic stroke, 72,342 (2.2%) received intravenous thrombolytic treatment and 13 799 (0.4%) underwent endovascular treatment. There was a 6-fold increase in patients who underwent endovascular treatment (0.1% of ischemic strokes in 2004 vs 0.6% in 2009; P<0.001), with the patients aged≥85 years having the lowest rate of utilization (0.2%). The rates of intracranial hemorrhage remained unchanged throughout the 6 years. In multivariate logistic regression analysis, after adjusting for age, gender, presence of hypertension, congestive heart failure, renal failure, and secondary intracranial hemorrhages, there was no difference in the rate of minimal disability between the 2 study intervals (2004-2007 vs 2008-2009; odds ratio, 0.8; 95% confidence interval, 0.7-1.04; P=0.11). Mortality decreased while moderate to severe disability increased for patients treated during 2008 to 2009 (odds ratio, 0.7; 95% confidence

  17. Acute Superior Mesenteric Venous Thrombosis: Transcatheter Thrombolysis and Aspiration Thrombectomy Therapy by Combined Route of Superior Mesenteric Vein and Artery in Eight Patients

    SciTech Connect

    Yang, Shuofei Liu, Baochen Ding, Weiwei He, Changsheng Wu, Xingjiang Li, Jieshou

    2015-02-15

    PurposeTo assess the feasibility, effectiveness, and safety of catheter-directed thrombolysis and aspiration thrombectomy therapy by combined route of superior mesenteric vein and artery (SMV+SMA) for acute superior mesenteric venous thrombosis (ASMVT).MethodsThis retrospective study reviewed eight ASMVT patients with transcatheter direct thrombolysis and aspiration thrombectomy therapy via SMV and indirect thrombolysis via SMA during a period of 14 months. The demographics, etiology, risk factors, therapeutic effect, complications, mortality, and follow-up of the study population were assessed. Anatomic and imaging classification of location and extent of thrombus at diagnosis and degree of thrombus lysis were described.ResultsTechnical success was achieved with substantial improvement in symptoms and thrombus resolution after thrombolytic therapy in all patients. The local urokinase infusion by SMA and SMV was performed for 5–7 (6.13 ± 0.83) and 7–15 (12 ± 2.51) days. Anticoagulation was performed catheter-directed and then orally throughout hospitalization and after discharge. Four patients required delayed localized bowel resection after thrombolytic therapy with no death. Thrombolytic therapy was not interrupted despite minor bleeding at the puncture site in two patients and sepsis in another two postoperatively. Nearly complete removal of thrombus was demonstrated by contrast-enhanced CT scan and portography before discharge. Patients were discharged in 10–27 (19.25 ± 4.89) days after admission. No recurrence developed during the follow-up of 10–13 (12.13 ± 0.99) months.ConclusionsCatheter-directed thrombolytic and aspiration therapy via SMV+SMA is beneficial for ASMVT in avoiding patient death, efficient resolving thrombus, rapid improving symptoms, reversing extensive intestinal ischemia, averting bowel resection, or localizing infarcted bowel segment and preventing short bowel syndrome.

  18. Endovascular stroke treatment now and then-procedural and clinical effectiveness and safety of different mechanical thrombectomy techniques over time.

    PubMed

    von Gadow, Niels; Nikoubashman, Omid; Freiherr, Jessica; Block, Frank; Reich, Arno; Fesl, Gunther; Wiesmann, Martin

    2017-02-01

    The most essential development in endovascular stroke treatment (EST) was the shift from intra-arterial thrombolysis to endovascular thrombectomy with dedicated thrombectomy devices, most notably the introduction of stent-retrievers. We evaluated procedural and clinical effectiveness and safety of different EST techniques over time. We retrospectively analyzed EST cases that were treated by the same interventionalist before (n=36) and after (n=50) stent-retrievers were established as the treatment device of first choice. EST techniques in the first cohort comprised intra-arterial thrombolysis (n=24), manual thrombus aspiration (n=15), the use of the Penumbra thrombectomy system (n=13) and the Phenox clot retriever (n=3), intracranial stenting (n=10), and EST with stent-retrievers as a salvage procedure (n=11). In the second cohort, EST with stent-retrievers was the treatment option of first choice (n=47). Intra-arterial thrombolysis (n=15) and stenting of the occluded vessel (n=1) were performed, whenever EST with stent-retrievers failed. In both cohorts, revascularization rates (TICI ≥2b) were high (91.7% and 86.0%, respectively). A significantly lower number of interventional techniques per case were required in the second cohort (mean ± SD, 1.4±0.5 vs. 2.1±0.9, P<0.001). Recanalization was achieved almost twice as fast in the second cohort (85 vs. 163 minutes on average, P<0.001). The rate of patients achieving good functional outcome (mRS ≤2) was higher in the second cohort (40.0% vs. 22.2%, P=0.083). Our findings imply that when stent-retrievers were established as first-line the treatment device a significantly lower number of interventional techniques per case were required and recanalization was achieved almost twice as fast.

  19. Endovascular stroke treatment now and then—procedural and clinical effectiveness and safety of different mechanical thrombectomy techniques over time

    PubMed Central

    von Gadow, Niels; Freiherr, Jessica; Block, Frank; Reich, Arno; Fesl, Gunther; Wiesmann, Martin

    2017-01-01

    Background The most essential development in endovascular stroke treatment (EST) was the shift from intra-arterial thrombolysis to endovascular thrombectomy with dedicated thrombectomy devices, most notably the introduction of stent-retrievers. We evaluated procedural and clinical effectiveness and safety of different EST techniques over time. Methods We retrospectively analyzed EST cases that were treated by the same interventionalist before (n=36) and after (n=50) stent-retrievers were established as the treatment device of first choice. EST techniques in the first cohort comprised intra-arterial thrombolysis (n=24), manual thrombus aspiration (n=15), the use of the Penumbra thrombectomy system (n=13) and the Phenox clot retriever (n=3), intracranial stenting (n=10), and EST with stent-retrievers as a salvage procedure (n=11). In the second cohort, EST with stent-retrievers was the treatment option of first choice (n=47). Intra-arterial thrombolysis (n=15) and stenting of the occluded vessel (n=1) were performed, whenever EST with stent-retrievers failed. Results In both cohorts, revascularization rates (TICI ≥2b) were high (91.7% and 86.0%, respectively). A significantly lower number of interventional techniques per case were required in the second cohort (mean ± SD, 1.4±0.5 vs. 2.1±0.9, P<0.001). Recanalization was achieved almost twice as fast in the second cohort (85 vs. 163 minutes on average, P<0.001). The rate of patients achieving good functional outcome (mRS ≤2) was higher in the second cohort (40.0% vs. 22.2%, P=0.083). Conclusions Our findings imply that when stent-retrievers were established as first-line the treatment device a significantly lower number of interventional techniques per case were required and recanalization was achieved almost twice as fast. PMID:28275555

  20. Presumed Pulmonary Embolism Following Power-Pulse Spray Thrombectomy of Upper Extremity Venous Thrombosis

    SciTech Connect

    Tsai, Jason; Georgiades, Christos S.; Hong, Kelvin; Kim, Hyun S.

    2006-08-15

    To achieve more effective thrombolysis in a shorter treatment time, percutaneous mechanical thrombectomy has been increasingly used in the treatment of deep venous thrombosis (DVT). The power-pulse spray is a new technique to combine chemical and rheolytic effects on clots. We present a case of presumed pulmonary embolism following power-pulse spray treatment for upper extremity DVT which necessitated resuscitation and intubation. The power-pulse spray technique should be used with caution when treating DVT.

  1. Successful Reperfusion With Mechanical Thrombectomy Is Associated With Reduced Disability and Mortality in Patients With Pretreatment Diffusion-Weighted Imaging-Alberta Stroke Program Early Computed Tomography Score ≤6.

    PubMed

    Desilles, Jean-Philippe; Consoli, Arthuro; Redjem, Hocine; Coskun, Oguzhan; Ciccio, Gabriele; Smajda, Stanislas; Labreuche, Julien; Preda, Cristian; Ruiz Guerrero, Clara; Decroix, Jean-Pierre; Rodesch, Georges; Mazighi, Mikael; Blanc, Raphaël; Piotin, Michel; Lapergue, Bertrand

    2017-04-01

    In acute ischemic stroke patients, diffusion-weighted imaging (DWI)-Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is correlated with infarct volume and is an independent factor of functional outcome. Patients with pretreatment DWI-ASPECTS ≤6 were excluded or under-represented in the recent randomized mechanical thrombectomy trials. Our aim was to assess the impact of reperfusion in pretreatment DWI-ASPECTS ≤6 patients treated with mechanical thrombectomy. We analyzed data collected between January 2012 and August 2015 in a bicentric prospective clinical registry of consecutive acute ischemic stroke patients treated with mechanical thrombectomy. Every patient with a documented internal carotid artery or middle cerebral artery occlusion with pretreatment DWI-ASPECTS ≤6 was eligible for this study. The primary end point was a favorable outcome defined by a modified Rankin Scale score ≤2 at 90 days. Two hundred and eighteen patients with a DWI-ASPECTS ≤6 were included. Among them, 145 (66%) patients had successful reperfusion at the end of mechanical thrombectomy. Reperfused patients had an increased rate of favorable outcome (38.7% versus 17.4%; P=0.002) and a decreased rate of mortality at 3 months (22.5% versus 39.1%; P=0.013) compared with nonreperfused patients. The symptomatic intracranial hemorrhage rate was not different between the 2 groups (13.0% versus 14.1%; P=0.83). However, in patients with DWI-ASPECTS <5, favorable outcome was low (13.0% versus 9.5%; P=0.68) with a high mortality rate (45.7% versus 57.1%; P=0.38) with or without successful reperfusion. Successful reperfusion is associated with reduced mortality and disability in patients with a pretreatment DWI-ASPECTS ≤6. Further data from randomized studies are needed, particularly in patients with DWI-ASPECTS <5. © 2017 American Heart Association, Inc.

  2. Mechanical Thrombectomy in and Outside the REVASCAT Trial: Insights From a Concurrent Population-Based Stroke Registry.

    PubMed

    Urra, Xabier; Abilleira, Sònia; Dorado, Laura; Ribó, Marc; Cardona, Pere; Millán, Mònica; Chamorro, Angel; Molina, Carlos; Cobo, Erik; Dávalos, Antoni; Jovin, Tudor G; Gallofré, Miquel

    2015-12-01

    Recent trials have shown the superiority of endovascular thrombectomy (EVT) over medical therapy alone in certain stroke patients with proximal arterial occlusion. Using data from the Randomized Trial of Revascularization With Solitaire FR Device Versus Best Medical Therapy in the Treatment of Acute Stroke due to Anterior Circulation Large Vessel Occlusion Presenting Within 8-Hours of Symptom Onset (REVASCAT) and a parallel reperfusion treatment registry, we sought to assess the utilization of EVT in a defined patient population, comparing the outcomes of patients treated in and outside the REVASCAT trial. SONIIA [Sistema Online d'Informació de l'Ictus Agut], a population-based, government-mandated, prospective registry of reperfusion therapies for stroke encompassing the entire population of Catalonia, was used as data source. The registry documents 5 key inclusion criteria of the REVASCAT trial: age, stroke severity, time to treatment, baseline functional status, and occlusion site. We compared procedural, safety, and functional outcomes in patients treated inside and outside the trial. From November 2012 to December 2014, out of 17596 ischemic stroke patients in Catalonia (population 7.5 million), 2576 patients received reperfusion therapies (17/100000 inhabitants-year), mainly intravenous thrombolysis only (2036). From the remaining 540 treated with EVT, 103 patients (out of 206 randomized) were treated within REVASCAT and 437 outside the trial. Of these, 399 did not fulfill some of the study criteria, and 38 were trial candidates (8 treated at REVASCAT centers and 30 at 2 non-REVASCAT centers). The majority of procedural, safety, and functional outcomes were similar in patients treated with EVT within and outside REVASCAT. REVASCAT enrolled nearly all eligible patients representing one third of all patients treated with EVT. Patients treated with EVT within and outside REVASCAT had similar outcomes, reinforcing the therapeutic value of EVT. URL: http

  3. Thrombectomy and thrombolysis: the interventional radiology approach.

    PubMed

    Dunn, Marilyn E

    2011-04-01

    To present interventional therapeutic options for patients with thrombosis. Thrombosis in small animals results from an unbalance in the normal hemostatic mechanisms leading to vessel occlusion. In veterinary medicine, thrombosis is recognized as a common complication of many acquired diseases, including cardiac, endocrine, immunological, inflammatory, and neoplastic disorders. Clinical signs are variable depending on the location of the thrombus and various laboratory and imaging modalities can aid in its identification and localization. Once identified, a decision must be made to whether or not intervene and which method is most appropriate. A number of minimally invasive approaches for dealing with thrombosis are available and offer veterinarians a choice of therapeutic options when dealing with a thrombotic patient. In the presence of thrombosis, a combined approach of vessel balloon dilatation, catheter-directed thrombolysis and stenting may be most appropriate. Percutaneous mechanical thrombectomy, if available, may also be appropriate. Embolic trapping devices can be used with vena cava thrombosis to help prevent pulmonary embolism. Anticoagulant therapy may be indicated in the postoperative period to prevent further thrombus formation while the patient's fibrinolytic system breaks the clot down. Outcome is variable depending on the site of the thrombus formation. Arterial thrombosis can be life-threatening while venous thrombosis tends to be less life-threatening but may lead to pulmonary embolism. © Veterinary Emergency and Critical Care Society 2011.

  4. Intraparenchymal Hyperattenuations on Flat-Panel CT Directly After Mechanical Thrombectomy are Restricted to the Initial Infarct Core on Diffusion-Weighted Imaging.

    PubMed

    Schneider, Tanja; Mahraun, Tobias; Schroeder, Julian; Frölich, Andreas; Hoelter, Philip; Wagner, Marlies; Darcourt, Jean; Cognard, Christophe; Bonafé, Alain; Fiehler, Jens; Siemonsen, Susanne; Buhk, Jan-Hendrik

    2016-09-16

    The presence of intraparenchymal hyperattenuations (IPH) on flat-panel computed tomography (FP-CT) after endovascular recanalization in stroke patients is a common phenomenon. They are thought to occur in ischemic areas with breakdown of the blood-brain barrier but previous studies that investigated a mutual interaction are scarce. We aimed to assess the relationship of IPH localization with prethrombectomy diffusion-weighted imaging (DWI) lesions. This retrospective multicenter study included 27 acute stroke patients who underwent DWI prior to FP-CT following mechanical thrombectomy. After software-based coregistration of DWI and FP-CT, lesion volumetry was conducted and overlapping was analyzed. Two different patterns were observed: IPH corresponding to the DWI lesion and IPH exceeding the DWI lesion. The latter showed demarcated infarction of DWI exceeding IPH at 24 h. No major hemorrhage following IPH was observed. Most IPH were manifested within the basal ganglia and insular cortex. The IPH primarily appeared within the initial ischemic core and secondarily within the penumbral tissue that progressed to infarction. The IPH represent the minimum final infarct volume, which may help in periinterventional decision making.

  5. Does Mechanical Thrombectomy in Acute Embolic Stroke Have Long-term Side Effects on Intracranial Vessels? An Angiographic Follow-up Study

    SciTech Connect

    Kurre, Wiebke Perez, Marta Aguilar; Horvath, Diana; Schmid, Elisabeth; Baezner, Hansjoerg; Henkes, Hans

    2013-06-15

    Purpose. Mechanical thrombectomy (mTE) proved to be effective treating acute vessel occlusions with an acceptable rate of procedural complications. Potential long-term side effects of the vessel wall trauma caused by mechanical irritation of the endothelium are unknown up to now. Methods. From a retrospectively established database of 640 acute stroke treatments, we selected 261 patients with 265 embolic vessel occlusions treated successfully by mTE without permanent implantation of a stent. Analysis comprised the type of devices used and the number of passes performed. Digital subtraction angiography immediately after treatment was evaluated for vasospasm, dissection, and extravasation. Control angiographic images were evaluated for any morphological change compared to the immediate posttreatment angiographic run. Results. Recanalization was achieved with a median of one (range 1-10) mTE maneuvers. Vasospasm occurred in 69 territories (26.0 %) and was treated with glyceroltrinitrate in three. Dissection was observed in one vessel (0.4 %). Intraprocedural hemorrhage in two patients (0.8 %) was either wire or device induced. Follow-up digital subtraction angiography was available for 117 territories after a median of 107 days, revealing target vessel occlusion in one segment (0.9 %) and a de novo stenosis of four segments (3.4 %). All findings were clinically asymptomatic. Posttreatment vasospasm was more frequent in patients with de novo stenosis and occlusion (p = 0.038). Conclusion. De novo stenoses and occlusions occur in a small proportion of patients after mTE. Because all lesions were clinically asymptomatic, this finding does not affect the overall benefit of the treatment. Vasospasm may predict late vessel wall changes.

  6. Stent Retriever Thrombectomy in Patients Who Are Ineligible for Intravenous Thrombolysis: A Multicenter Retrospective Observational Study.

    PubMed

    Dorn, F; Prothmann, S; Patzig, M; Lockau, H; Kabbasch, C; Nikoubashman, O; Liebig, T; Zimmer, C; Brückmann, H; Wiesmann, M; Stetefeld, H; Poppert, H; Reich, A; Kellert, L; Fesl, G

    2016-02-01

    Intravenous thrombolysis with rtPA is the standard of care for patients with acute ischemic stroke within 4.5 hours after symptom onset. However, a considerable number of patients are ineligible for IV thrombolysis due to various contraindications. Recent studies have proved the superiority of mechanical thrombectomy for patients with large-vessel occlusions in combination with IV rtPA compared with IV rtPA alone. We aimed to demonstrate the efficacy of mechanical thrombectomy for patients who are ineligible for IV rtPA. Patients from the stroke registries of 4 dedicated centers who were treated with mechanical thrombectomy from January 2010 to October 2014 were retrospectively evaluated. Inclusion criteria were the following: acute stroke due to proved large-artery occlusion, ineligibility for IV thrombolysis, and a timeframe of ≤4.5 hours between stroke and the start of mechanical thrombectomy. Recanalization success, periprocedural complications, clinical outcome, and hemorrhages were evaluated. One hundred thirty endovascular recanalization procedures were identified. The locations were the following: proximal ICA in 17 (13.1%), terminus ICA in 25 (19.2%), M1 segment in 77 (59.2%), and M2 segment in 11 (8.5%). TICI 2b/3 results were achieved in 101 (77.7%), and an mRS score of 0-2 in 47 patients (37.9%). There was a significant correlation between TICI 2b/3 results and good clinical outcomes (87.2% versus 6.8%; P = .048). A good clinical result was most frequent when recanalization was achieved within 4.5 hours (37/74 = 50% versus 10/50 = 20.0%; P = .001). Symptomatic hemorrhage occurred in 13.1% of patients; mortality was 24.2%. Periprocedural complications were recorded in 10 patients (7.7%). Mechanical thrombectomy can achieve good clinical outcomes in patients with acute large-artery occlusion ineligible for IV thrombolysis, in particular when recanalization is reached early. © 2016 by American Journal of Neuroradiology.

  7. Amplatz Thrombectomy Device: Unexpected Interaction with the Cragg Endoprosthesis

    SciTech Connect

    Schwarzenberg, Helmut; Mueller-Huelsbeck, Stefan; Heller, Martin

    1998-01-15

    In a 74-year-old woman, a Dacron-covered Cragg endoprosthesis was implanted into the left superficial femoral artery after successful recanalization of a 6-cm-long occlusion. At 4.5 months after discharge the endoprosthesis was occluded. In order to perform a thrombectomy, an Amplatz thrombectomy device (ATD) was activated and advanced into the occluded graft. Suddenly, a mechanical failure of the ATD occurred. Extraction of the ATD was achieved only after repeated attempts at rotating motion and jerky pullback maneuvers. The most likely explanation is that one of the graft-struts had advanced into the tip of the ATD and resulted in a broken drive shaft. Recanalization was completed by performing percutaneous transluminal angioplasty and pharmacological thrombolysis with recombinant human-tissue plasminogen activator. In conclusion, users of the ATD have to be aware of interactions of the ATD with the struts of implanted stents or grafts during thrombectomy.

  8. Single center experience of Mechanical thrombectomy with the Trevo XP ProVue 6×25 mm stent retriever in MCA occlusion : Comparison with Trevo XP ProVue 4×20 mm.

    PubMed

    Yi, Ho Jun; Sung, Jae Hoon; Lee, Dong Hoon; Hong, Jae Taek; Lee, Sang Won

    2017-08-18

    There are a few studies assessing the suitable stent size for mechanical thrombectomy in MCA occlusion. So, the authors attempted to determine what size of a stent is suitable for thrombectomy in MCA occlusion through a comparison of Trevo XP 6×25 mm and 4×20 mm stents. The authors changed Trevo XP 4×20 mm stent to Trevo XP 6×25 mm stents for thrombectomy in MCA occlusion with the hypothesis that larger size stent would make better outcomes. Retrospectively, a total of 87 patients were divided into two groups : Trevo XP 6×25 mm stents group and Trevo XP 4×20 mm stent group, and comparative study was performed in terms of clinical, radiologic outcomes and complications. The proportion of patients with a good clinical outcome and successful recanalization was higher in Trevo XP 6×25 mm stent group than in Trevo XP 4×20 mm stent group with statistical significance (p = 0.041, p = 0.036). In multivariate analysis, the use of Trevo 6×25 mm stent was a predictive factor for a good clinical outcome (OR 1.22 [95% CI 1.06-1.38], p=0.03) and successful recanalization (OR 1.89 [95% CI 1.25-2.87], p=0.018). However, there was no statistically significant difference in complication between the two groups. Our study revealed that the Trevo XP 6×25 mm stent provides better clinical and radiological outcomes than the Trevo XP 4×20 mm stent for MCA occlusion without an increase in the rate of complications. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Does Preinterventional Flat-Panel Computer Tomography Pooled Blood Volume Mapping Predict Final Infarct Volume After Mechanical Thrombectomy in Acute Cerebral Artery Occlusion?

    SciTech Connect

    Wagner, Marlies; Kyriakou, Yiannis; Mesnil de Rochemont, Richard du; Singer, Oliver C.; Berkefeld, Joachim

    2013-08-01

    PurposeDecreased cerebral blood volume is known to be a predictor for final infarct volume in acute cerebral artery occlusion. To evaluate the predictability of final infarct volume in patients with acute occlusion of the middle cerebral artery (MCA) or the distal internal carotid artery (ICA) and successful endovascular recanalization, pooled blood volume (PBV) was measured using flat-panel detector computed tomography (FPD CT).Materials and MethodsTwenty patients with acute unilateral occlusion of the MCA or distal ACI without demarcated infarction, as proven by CT at admission, and successful Thrombolysis in cerebral infarction score (TICI 2b or 3) endovascular thrombectomy were included. Cerebral PBV maps were acquired from each patient immediately before endovascular thrombectomy. Twenty-four hours after recanalization, each patient underwent multislice CT to visualize final infarct volume. Extent of the areas of decreased PBV was compared with the final infarct volume proven by follow-up CT the next day.ResultsIn 15 of 20 patients, areas of distinct PBV decrease corresponded to final infarct volume. In 5 patients, areas of decreased PBV overestimated final extension of ischemia probably due to inappropriate timing of data acquisition and misery perfusion.ConclusionPBV mapping using FPD CT is a promising tool to predict areas of irrecoverable brain parenchyma in acute thromboembolic stroke. Further validation is necessary before routine use for decision making for interventional thrombectomy.

  10. The Penumbra 5MAX ACE Catheter Is Safe, Efficient, and Cost Saving as a Primary Mechanical Thrombectomy Device for Large Vessel Occlusions in Acute Ischemic Stroke

    PubMed Central

    Vidal, Gabriel A.; Milburn, James M.

    2016-01-01

    catheter can be considered a first-line approach to mechanical thrombectomy for large vessel occlusions. Our results demonstrated high rates of successful reperfusion in a timely manner with excellent clinical outcomes, although our sample size was small. In addition, this direct-aspiration technique has important cost-savings potential compared to stent retrievers. PMID:27999507

  11. Endovascular Mechanical Thrombectomy of an Occluded Superior Division Branch of the Left MCA for Acute Cardioembolic Stroke

    SciTech Connect

    Schumacher, H. C. Meyers, P. M.; Yavagal, D. R.; Harel, N. Y.; Elkind, M. S. V.; Mohr, J. P.; Pile-Spellman, J.

    2003-06-15

    Cardiac embolism accounts for a large proportion of ischemic stroke. Revascularization using systemic or intra-arterial thrombolysis is associated with increasing risks of cerebral hemorrhageas time passes from stroke onset. We report successful mechanicalthrombectomy from a distal branch of the middle cerebral artery (MCA)using a novel technique. A 72-year old man suffered an acute ischemic stroke from an echocardiographically proven ventricular thrombus due toa recent myocardial infarction. Intra-arterial administration of 4 mgrt-PA initiated at 5.7 hours post-ictus failed to recanalize an occluded superior division branch of the left MCA. At 6 hours,symptomatic embolic occlusion persisted. Mechanical extraction of the clot using an Attracter-18 device (Target Therapeutics, Freemont, CA) resulted in immediate recanalization of the MCA branch. Attracter-18 for acute occlusion of MCA branches may be considered in selected patients who fail conventional thrombolysis or are nearing closure of the therapeutic window for use of thrombolytic agents.

  12. Mechanical thrombectomy using Rotarex system and stent-in-stent placement for treatment of distal femoral artery occlusion secondary to stent fracture – a case report and literature review

    PubMed Central

    Dys, Krzysztof; Drelichowska-Durawa, Justyna; Dołega-Kozierowski, Bartosz; Lis, Michał; Sokratous, Kyriakos; Iwanowski, Wojciech; Drelichowski, Stanisław; Witkiewicz, Wojciech

    2013-01-01

    Summary Background: Treatment of peripheral arterial diseases may be distinguished into conservative and interventional management; the latter is divided into surgical and endovascular procedures. Management of peripheral artery stenosis and occlusion with vascular stents is associated with the risk of late complications such as restenosis, stent fracture or dislocation. Case Report: A 62-year-old woman with generalized atherosclerosis, particularly extensive in lower limb arteries, was admitted to the Department of Angiology 11 months after having an endovascular procedure performed due to critical ischemia of left lower limb. Because of stent occlusion, a decision to perform angiographic examination of lower limb arteries was made. Examination revealed occlusion of the superficial femoral artery along its entire length, including previously implanted stents. Distal stent was fractured with slight dislocation of the proximal segment. A decision was made to perform mechanical thrombectomy using a Rotarex system followed by a stent-in-stent placement procedure. Follow-up angiography and ultrasound scan performed 24 hours after the procedure revealed a patent vessel with satisfactory blood flow. Discussion: Nowadays, imaging diagnostics of peripheral artery stenosis involves non-invasive examinations such as ultrasound, minimally invasive examinations such as angio-MRI and MDCT, or invasive examinations such as DSA and IVUS. DSA examinations are used to confirm significant stenosis or occlusion of a vessel, particularly when qualifying a patient for endovascular treatment. Due to their anatomic location, the superficial femoral artery and the popliteal artery are subject to various forces e.g. those exerted by the working muscles. Mechanical thrombectomy and atherectomy are efficient methods of arterial recanalization used in the treatment of acute, subacute or even chronic occlusions or stenosis of peripheral vessels. Conclusions: Frequency of angioplasty and

  13. Stent retriever thrombectomy for acute ischemic stroke: Indications, results and management in 2015.

    PubMed

    Gory, B; Riva, R; Labeyrie, P E; Turjman, F

    2016-02-01

    The functional benefit of stent retriever thrombectomy in acute ischemic stroke has been clearly demonstrated in recent positive MR CLEAN, ESCAPE, EXTEND-IA, SWIFT PRIME, REVASCAT and THRACE trials. Thrombectomy, in association with intravenous thrombolysis, should now be offered to patients with documented occlusion of the distal internal carotid or proximal middle cerebral arteries, with a relatively normal unenhanced computed tomography (CT), and within 6hours after the onset of symptoms. Thrombectomy results in a mean absolute decrease in handicap of 22% (14 to 31%). Of the 3 up to 8 patients treated, 1 is independent at 3 months according to the initial selection. In case of a contraindication to thrombolysis, early primary thrombectomy should be considered. In acute basilar artery occlusion, thrombectomy should be performed alone or combined with thrombolysis. In an effort to increase the number of patients treated, a very rapid transfer to interventional neuroradiology centers is mandatory. In the future, thrombectomy should be evaluated in patients with distal arterial occlusion, or beyond 6hours after the onset of symptoms, or when the time of symptoms onset is unknown.

  14. Cerebral Granulomatous Inflammation Secondary to Hydrophilic Polymer Embolization Following Thrombectomy

    PubMed Central

    Meiers, Craig; Abebe, Yoftahe; Alberto, Neville; Riedinger, John; Breker, Dane; Manchak, Michael; Drofa, Alexander; Teigen, Corey

    2017-01-01

    Patient: Female, 59 Final Diagnosis: Granulomatous response to microscopic polymer Symptoms: Worsening neurologic deficit Medication: — Clinical Procedure: Mechanical thrombectomy Specialty: Neurosurgery Objective: Unusual or unexpected effect of treatment Background: Given the recent completion of multiple trials demonstrating the benefit of endovascular mechanical thrombectomy for select patients with proximal large artery occlusive ischemic strokes, there has been a large increase in the performance of these procedures. In the context of increased thrombectomy performance, there have also been increased reports of rare occurrences of granulomatous inflammatory response to the hydrophilic polymer which coat many of these interventional devices. Case Report: A 59-year-old female presented with a complete occlusion of her right proximal middle cerebral artery (MCA) and imaging showed a large area of penumbra. Cerebral angiogram and mechanical thrombectomy were successfully performed with reversal of clinical symptoms. Eight months following her stroke, she developed progressive recurrence of left-sided neurological deficits. After extensive workup culminating in tissue sampling, she was found to have developed granulomatous inflammation surrounding microscopic embolization of hydrophilic polymer, which is used to coat many interventional devices such as wires and catheters. The patient responded both clinically and radiographically to anti-inflammatory steroid therapy. Conclusions: Recognizing the significant potential morbidity of a large vessel ischemic stroke and the expanded use of endovascular interventions aimed at staving off this disability, there are emerging and at times indolent complications from the use of hydrophilic polymer coated wires and catheters. This rare and potentially under-recognized complication should be considered in the differential for any patient with new neurological findings following cerebral intervention, especially given the

  15. Emergent Right Coronary Artery Thrombectomy with a Jet Aspiration Thrombectomy Catheter

    SciTech Connect

    Yamauchi, Teiyu; Furui, Shigeru; Isshiki, Takaaki; Toyoizumi, Hideki; Kohtake, Hiroshi; Takeshita, Kohji; Suzuki, Shigeru; Harasawa, Arimi; Sasaki, Yasushi

    1999-07-15

    A saline-jet aspiration thrombectomy (JAT) catheter was used in a patient with acute myocardial infarction. A right coronary arteriogram showed complete thrombotic occlusion at the proximal segment. With this catheter the thrombus was removed without complications in 5 sec. The patient underwent percutaneous transluminal coronary angioplasty and placement of a Palmaz-Schatz stent after successful thrombectomy. Thrombectomy with a JAT catheter was very useful in this patient.0.

  16. Cerebral Granulomatous Inflammation Secondary to Hydrophilic Polymer Embolization Following Thrombectomy.

    PubMed

    Meiers, Craig; Abebe, Yoftahe; Alberto, Neville M; Riedinger, John; Breker, Dane A; Manchak, Michael; Drofa, Alexander; Teigen, Corey

    2017-05-08

    BACKGROUND Given the recent completion of multiple trials demonstrating the benefit of endovascular mechanical thrombectomy for select patients with proximal large artery occlusive ischemic strokes, there has been a large increase in the performance of these procedures. In the context of increased thrombectomy performance, there have also been increased reports of rare occurrences of granulomatous inflammatory response to the hydrophilic polymer which coat many of these interventional devices. CASE REPORT A 59-year-old female presented with a complete occlusion of her right proximal middle cerebral artery (MCA) and imaging showed a large area of penumbra. Cerebral angiogram and mechanical thrombectomy were successfully performed with reversal of clinical symptoms. Eight months following her stroke, she developed progressive recurrence of left-sided neurological deficits. After extensive workup culminating in tissue sampling, she was found to have developed granulomatous inflammation surrounding microscopic embolization of hydrophilic polymer, which is used to coat many interventional devices such as wires and catheters. The patient responded both clinically and radiographically to anti-inflammatory steroid therapy. CONCLUSIONS Recognizing the significant potential morbidity of a large vessel ischemic stroke and the expanded use of endovascular interventions aimed at staving off this disability, there are emerging and at times indolent complications from the use of hydrophilic polymer coated wires and catheters. This rare and potentially under-recognized complication should be considered in the differential for any patient with new neurological findings following cerebral intervention, especially given the consideration that this appears to a treatable complication.

  17. Thrombectomy in patients ineligible for iv tPA (THRILL).

    PubMed

    Bendszus, Martin; Thomalla, Götz; Knauth, Michael; Hacke, Werner; Bonekamp, Susanne; Fiehler, Jens

    2015-08-01

    A relevant proportion of patients with acute ischemic stroke are ineligible for intravenous thrombolysis with recombinant tissue plasminogen activator. Mechanical thrombectomy offers a treatment alternative for these patients; however, only few data are available on its safety and efficacy. The aim of this study was to compare safety and efficacy of stent retrievers as device class with best medical care alone in acute stroke patients with large intracranial vessel occlusion in the anterior circulation who are not eligible for intravenous thrombolysis with recombinant tissue plasminogen activator up to eight-hours of symptom onset. 'Thrombectomy in patients ineligible for iv tPA' is a prospective, open-label, blinded end-point, binational (Germany and Austria), two-arm, randomized, controlled, post-market study. Primary end-point is the modified Rankin Score shift analysis 90 days (±14) after stroke. Secondary end-points are excellent neurological outcomes (modified Rankin Score ≤ 1), good neurological outcomes (modified Rankin Score ≤ 2 or National Institutes of Health Stroke Scale improvement ≥ 10), difference between predicted infarct volume and actual core infarct volume (computed tomography or magnetic resonance imaging) at 30 (±6) h post-ictus, successful recanalization (thrombolysis in cerebral infarction score 2b or 3), functional health status 90 (±14) days after stroke (European Quality of Life-5 Dimensions) as well as common safety end-points (adverse event, serious adverse event, symptomatic intracranial haemorrhage at 30 (±6) h, death, or dependency). Whether mechanical thrombectomy in patients with acute ischemic stroke who are not eligible for intravenous thrombolysis with recombinant tissue plasminogen activator improves clinical outcomes is unclear. 'Thrombectomy in patients ineligible for iv tPA' may change clinical practice by providing evidence of an effective and safe treatment for such patients. © 2015 World Stroke

  18. The transient intraluminal filament middle cerebral artery occlusion model as a model of endovascular thrombectomy in stroke.

    PubMed

    Sutherland, Brad A; Neuhaus, Ain A; Couch, Yvonne; Balami, Joyce S; DeLuca, Gabriele C; Hadley, Gina; Harris, Scarlett L; Grey, Adam N; Buchan, Alastair M

    2016-02-01

    The clinical relevance of the transient intraluminal filament model of middle cerebral artery occlusion (tMCAO) has been questioned due to distinct cerebral blood flow profiles upon reperfusion between tMCAO (abrupt reperfusion) and alteplase treatment (gradual reperfusion), resulting in differing pathophysiologies. Positive results from recent endovascular thrombectomy trials, where the occluding clot is mechanically removed, could revolutionize stroke treatment. The rapid cerebral blood flow restoration in both tMCAO and endovascular thrombectomy provides clinical relevance for this pre-clinical model. Any future clinical trials of neuroprotective agents as adjuncts to endovascular thrombectomy should consider tMCAO as the model of choice to determine pre-clinical efficacy.

  19. Successful carbon dioxide angiography guided endovascular thrombectomy of the superficial femoral artery in a young patient with critical limb ischemia.

    PubMed

    Giusca, Sorin; Eisele, Tom; Raupp, Dorothea; Eisenbach, Christoph; Korosoglou, Grigorios

    2017-03-01

    Currently, the treatment of thromboembolic ischemia of the lower extremities includes percutaneous rotational thrombectomy and aspiration devices. However, the standard approach for endovascular treatment requires the administration of iodine contrast agents, which is problematic in patients with pre-existing renal disease and diabetes. Herein, we describe a case of a CO2 angiography guided endovascular thrombectomy of the superficial femoral artery (SFA) in a young patient with critical limb ischemia. Mechanical thrombectomy using the Rotarex system, catheter aided aspiration and subsequent stent placement in the SFA was entirely guided using CO2 angiography.

  20. Anchor technique: Use of stent retrievers as an anchor to advance thrombectomy catheters in internal carotid artery occlusions

    PubMed Central

    Wolfe, Stacey Q; Janjua, Rashid M; Hedayat, Hirad; Burnette, Christofer

    2015-01-01

    In three recent cases of acute complete internal artery occlusions, we used stent retriever deployed through the mechanical aspiration/distal access catheters to achieve recanalization. In all cases the stent retriever was used as an anchor and supplemented mechanical thrombectomy. This report describes the technical details of the procedure and presents an alternative plan of action in difficult cases when standard thrombectomy techniques do not work. PMID:26494404

  1. Massive Pulmonary Embolism: Treatment with the Rotarex Thrombectomy System

    SciTech Connect

    Liu Sheng; Shi Haibin; Gu Jianping; Yang Zhengqiang; Chen Liang; Lou Wensheng; He Xu; Zhou Weizhong; Zhou Chungao; Zhao Linbo; Xia Jinguo; Li Linsun

    2011-02-15

    This study was designed to evaluate the efficacy and safety of percutaneous mechanical thrombectomy (PMT) for acute massive pulmonary embolism (PE). Fourteen patients (8 men, 6 women) with a mean age of 55.4 (range, 38-71) years with acute massive PE were initially diagnosed by computed tomography (CT) and confirmed by pulmonary angiography. All patients presented with acute PE symptoms and hemodynamic compromise. Each patient was treated with Straub Rotarex thrombectomy device and five patients received additional thrombolysis. Technique success and clinical improvement were achieved in all patients without major complications. The mean pulmonary artery pressure (PAP) decreased from 37.6 {+-} 6.6 to 29 {+-} 6.4 mmHg (P < 0.01) after PMT. Partial arterial pressures of O{sub 2} (PaO{sub 2}) increased from 61.1 {+-} 9.2 to 88 {+-} 5.1 mmHg (P < 0.01). The Miller index was 0.67 {+-} 0.11 and 0.37 {+-} 0.13 (P < 0.01), respectively, before and after PMT (P < 0.01). Eleven patients had no recurrence of PE on a mean follow-up of 28.3 months, whereas the other three patients were lost to follow-up. The preliminary experience in our series suggests that the Straub Rotarex thrombectomy device, which has been utilized in peripheral arteries, also is useful for the treatment of acute massive PE.

  2. Infective Endocarditis Complicated by Acute Ischemic Stroke from Septic Embolus: Successful Solitaire FR Thrombectomy

    PubMed Central

    Liang, Jackson J; Bishu, Kalkidan G; Anavekar, Nandan S

    2012-01-01

    Infective endocarditis (IE) is often complicated by systemic embolization. Acute stroke due to septic emboli is a particularly dreaded complication. Optimal treatment for acute stroke in IE has not been well outlined. Fibrinolytic therapy may be associated with increased risk for hemorrhagic transformation in patients with acute stroke in the setting of IE. We present a case of IE complicated by acute stroke which was successfully treated with mechanical thrombectomy. This case illustrates a role of mechanical thrombectomy devices in this patient population.

  3. [Open thrombectomy in acute iliofemoral venous thrombosis].

    PubMed

    Pokrovskiĭ, A V; Ignat'ev, I M; Gradusov, E G; Bredikhin, R A

    2017-01-01

    The study was aimed at assessing efficacy of open thrombectomy in acute iliofemoral venous thrombosis. From January 2012 to December 2016, a total of 37 patients underwent transfemoral thrombectomy for acute iliofemoral venous thrombosis. The Control Group consisted of 24 patients receiving standard anticoagulant therapy. Six patients were subjected to a hybrid operation consisting in thrombectomy supplemented with stenting of the residual compression stenosis of the left common iliac vein (CIV). The outcomes of the operations were controlled by means of duplex scanning. Clinical efficacy of the operations was evaluated with the help of the Venous Clinical Severity Score (VCSS) and CEAP classification. Patency of the iliofemoral segment at 6 months of follow up after thrombectomy was observed in 92% of patients. At the same time, in patients receiving anticoagulant therapy recanalization of the iliofemoral segment was observed in only 21% (5/24; χ2=31, p<0.01) of cases. Recanalization of the femoropopliteal segment 6 months after thrombectomy was noted to occur in 70% (23/33) of patients. The median of the composite index by the VCSS after 6 months decreased from 7 to 2 (p=0.002). The cumulative patency of the iliofemoral segment 36 months after surgery amounted to 86%. Clinical assessment of the remote results of thrombectomy according to the CEAP classification demonstrated that 90% (19/21) of patients were either free from or had weakly pronounced symptoms of post-thrombotic syndrome. Performing thrombectomy for iliofemoral thrombosis by selective indications using modern methods of restoring patency of deep veins significantly increases efficacy of treating patients presenting with this severe pathology and prevents the development of pronounced manifestations of post-thrombotic syndrome.

  4. Percutaneous Venous Thrombectomy Using the Arrow-Trerotola Percutaneous Thrombolytic Device (PTD) with Temporary Caval Filtration: In Vitro Investigations

    SciTech Connect

    Wildberger, Joachim Ernst Haage, Patrick; Bovelander, Jan; Pfeffer, Joachim; Weiss, Claudia; Vorwerk, Dierk; Schmitz-Rode, Thomas; Guenther, Rolf W.

    2005-04-15

    Purpose. To evaluate the size and quantity of downstream emboli after thrombectomy using the Arrow-Trerotola Percutaneous Thrombolytic Device (PTD) with or without temporary filtration for extensive iliofemoral and iliocaval thrombi in an in vitro flow model. Methods. Iliocaval thrombi were simulated by clotted bovine blood in a flow model (semilucent silicone tubings, diameter 12-16 mm). Five experimental set-ups were performed 10 times each; thrombus particles and distribution were measured in the effluent. First, after retrograde insertion, mechanical thrombectomy was performed using the PTD alone. Then a modified self-expanding tulip-shaped temporary vena cava stent filter was inserted additionally at the beginning of each declotting procedure and removed immediately after the intervention without any manipulation within or at the filter itself. In a third step, the filter was filled with thrombus only. Here, two experiments were performed: Careful closure within the flow circuit without any additional fragmentation procedure and running the PTD within the filter lumen, respectively. In the final set-up, mechanical thrombectomy was performed within the thrombus-filled tubing as well as in the filter lumen. The latter was closed at the end of the procedure and both devices were removed from the flow circuit. Results. Running the PTD in the flow circuit without filter protection led to a fragmentation of 67.9% ({+-}7.14%) of the clot into particles {<=}500 {mu}m; restoration of flow was established in all cases. Additional placement of the filter safely allowed maceration of 82.9% ({+-}5.59%) of the thrombus. Controlled closure of the thrombus-filled filter within the flow circuit without additional mechanical treatment broke up 75.2% ({+-}10.49%), while additional mechanical thrombectomy by running the PTD within the occluded filter led to dissolution of 90.4% ({+-}3.99%) of the initial clot. In the final set-up, an overall fragmentation rate of 99.6% ({+-}0

  5. Evolution of thrombectomy approaches and devices for acute stroke: a technical review.

    PubMed

    Spiotta, Alejandro M; Chaudry, M Imran; Hui, Ferdinand K; Turner, Raymond D; Kellogg, Ryan T; Turk, Aquilla S

    2015-01-01

    While intravenous administration of tissue plasminogen activator (tPA) remains the only FDA-approved treatment modality for acute ischemic stroke, many patients do not meet the criteria for intravenous tPA and are offered intra-arterial therapy. Rapid advances in devices and approaches have marked the evolution of thrombectomy over the past decade from rudimentary mechanical disruption, followed by intra-arterial thrombolytic infusions to increasingly effective thrombectomy devices. We review the critical advancements in thrombectomy technique that have evolved and the key anatomic and technical challenges they address, from first-generation Merci retrieval systems to second-generation Penumbra aspiration systems and third-generation stent retrievers, as well as nuances of their uses to maximize their effectiveness. We also highlight more recent advances that offer patients hope for more expedient vessel recanalization.

  6. Massive Pulmonary Embolism: Percutaneous Emergency Treatment Using an Aspirex Thrombectomy Catheter

    SciTech Connect

    Popovic, Peter; Bunc, Matjaz

    2010-10-15

    Massive pulmonary embolism (PE) is a life-threatening condition with a high early mortality rate caused by acute right ventricular failure and cardiogenic shock. A 51-year-old woman with a massive PE and contraindication for thrombolytic therapy was treated with percutaneous mechanical thrombectomy using an Aspirex 11F catheter (Straub Medical AG, Wangs, Switzerland). The procedure was successfully performed and showed a good immediate angiographic result. The patient made a full recovery from the acute episode and was discharged on heparin treatment. Our case report indicates that in patients with contraindications to systemic thrombolysis, catheter thrombectomy may constitute a life-saving intervention for massive PE.

  7. Surgical Thrombectomy for Phlegmasia Cerulea Dolens

    PubMed Central

    Yang, Shin-Seok; Yun, Woo-Sung

    2016-01-01

    Phlegmasia cerulea dolens (PCD) is a medical emergency that can lead to venous gangrene of the lower extremity. Early diagnosis and prompt treatment is crucial for limb salvage. There are two treatment options (endovascular or surgical). In the endovascular era, catheter-directed thrombolysis is the treatment of choice to achieve venous outflow. However, surgical thrombectomy is indicated in certain cases. The authors report successful surgical thrombectomy in a 75-year-old man with PCD and review the treatment of PCD. PMID:28042562

  8. Massive pulmonary embolism: treatment with the rotarex thrombectomy system.

    PubMed

    Liu, Sheng; Shi, Hai-Bin; Gu, Jian-Ping; Yang, Zheng-Qiang; Chen, Liang; Lou, Wen-Sheng; He, Xu; Zhou, Wei-Zhong; Zhou, Chun-Gao; Zhao, Lin-Bo; Xia, Jin-Guo; Li, Lin-Sun

    2011-02-01

    This study was designed to evaluate the efficacy and safety of percutaneous mechanical thrombectomy (PMT) for acute massive pulmonary embolism (PE). Fourteen patients (8 men, 6 women) with a mean age of 55.4 (range, 38-71) years with acute massive PE were initially diagnosed by computed tomography (CT) and confirmed by pulmonary angiography. All patients presented with acute PE symptoms and hemodynamic compromise. Each patient was treated with Straub Rotarex thrombectomy device and five patients received additional thrombolysis. Technique success and clinical improvement were achieved in all patients without major complications. The mean pulmonary artery pressure (PAP) decreased from 37.6 ± 6.6 to 29 ± 6.4 mmHg (P < 0.01) after PMT. Partial arterial pressures of O(2) (PaO(2)) increased from 61.1 ± 9.2 to 88 ± 5.1 mmHg (P < 0.01). The Miller index was 0.67 ± 0.11 and 0.37 ± 0.13 (P < 0.01), respectively, before and after PMT (P < 0.01). Eleven patients had no recurrence of PE on a mean follow-up of 28.3 months, whereas the other three patients were lost to follow-up. The preliminary experience in our series suggests that the Straub Rotarex thrombectomy device, which has been utilized in peripheral arteries, also is useful for the treatment of acute massive PE.

  9. Recanalization of thrombosed superficial femoral arteries with a hydraulic thrombectomy catheter in a canine model.

    PubMed

    Qian, Z; Wholey, M; Ferral, H; Maynar, M; Postoak, D; Hamide, J; Newman, W P; Moncada, R; Gonzalez-Roman, A; Gimenez, C; Castañeda, W R

    1999-12-01

    This experiment was conducted to evaluate efficacy and safety of the Oasis thrombectomy catheter on arterial thrombosis in dogs. Thrombosis was induced in 18 femoral arteries of nine mongrel dogs. Recanalization of the thrombosed femoral artery was performed using a thrombectomy catheter 7-10 days after thrombus induction. Pre- and postprocedural arterial status was documented by angiography. After mechanical thrombectomy, the animals were sacrificed and the femoral arteries were harvested and examined macro- and microscopically. Additionally, in vitro fragmentation was carried out to determine particle size and distribution from the recovered effluent. Subacute thrombosis was successfully created in 15 femoral arteries. Full recanalization was achieved in 80% (12/15) of the thrombosed femoral arteries without any residual thrombus. No significant downstream embolization was documented angiographically. Endothelial denudation was observed in all the treated arteries along with occasional disruption of the internal elastic lamina. No medial injury was seen. Ninety-eight percent of thrombus was liquefied, defined as particles smaller than 15 microm, by the catheter. Particles larger than 400 microm represented 0.27% of the original clot weight. Occluded femoral arteries with 7- to 10-day-old thrombus can be efficiently recanalized with the Oasis catheter in dogs without any significant complication. This thrombectomy catheter appears to be highly effective and safe and requires no sophisticated equipment. Blood loss was our major concern regarding use of this catheter but can be minimized by strictly controlling activation time and restricting the inflow into the vascular segment being treated.

  10. Effect of Coronary Thrombectomy in Cardiogenic Shock Complicating ST-Segment Elevation Myocardial Infarction.

    PubMed

    Suzuki, Makoto; Sumiyoshi, Tetsuya; Miyachi, Hideki; Yamashita, Jun; Yamasaki, Masao; Miyauchi, Katsumi; Yamamoto, Takeshi; Nagao, Ken; Tomoike, Hitonobu; Takayama, Morimasa

    2015-06-15

    Optimal coronary reflow is the critical key issue to ameliorate clinical outcomes in patients with cardiogenic shock complicating ST-segment elevation myocardial infarction (Shock-STEMI). We investigated our hypothesis that pre-percutaneous coronary intervention (PCI) procedural coronary thrombectomy may provide clinical advantages to attempt optimal coronary reflow in patients with Shock-STEMI. Of 7,650 patients with acute myocardial infarction registered in the Tokyo CCU Network Scientific Council from January 2009 to December 2011, a total of 180 consecutive patients (144 men, 68 ± 13 years) with Shock-STEMI who showed pre-PCI procedural Thrombolysis in Myocardial Infarction flow grade 0 (absent initial coronary flow) were recruited. Achievements of post-PCI procedural Thrombolysis in Myocardial Infarction flow grade 3 (optimal coronary reflow) and also in-hospital mortality were evaluated in those in accordance with and without coronary thrombectomy. Coronary thrombectomy was performed in 128 patients with Shock-STEMI (71% of all). Overall in-hospital mortality was 41% and that in anterior Shock-STEMI with a necessity of mechanical circulatory support increased by 59% (i.e., profound shock). Coronary thrombectomy did not affect any improvements in the achievement of optimal coronary reflow (65% vs 58%, p = 0.368) and in-hospital mortality (42% vs 37%, p = 0.484) in these patients. Even when focused on 76 patients with profound shock, neither an achievement of optimal coronary reflow (56% vs 47%, p = 0.518) nor in-hospital mortality (58% vs 65%, p = 0.601) were different between with and without coronary thrombectomy. Multivariate logistic analysis did not demonstrate any association of coronary thrombectomy (p = 0.798), left main Shock-STEMI (p = 0.258), and use of mechanical circulatory support (p = 0.119) except a concentration of hemoglobin (for each 1 g/dl increase, odds ratio 1.247, 95% confidence interval 1.035 to 1.531, p = 0.019) with optimal

  11. Endovascular thrombectomy and post-procedural headache.

    PubMed

    Khan, Sabrina; Amin, Faisal Mohammad; Holtmannspötter, Markus; Hansen, Klaus; Florescu, Anna Maria; Fakhril-Din, Zainab; Petersen, Julie Falkenberg; Ghanizada, Hashmat; Ayata, Cenk; Gaist, David; Ashina, Messoud

    2017-12-01

    We investigated the prevalence of post-procedural headache in patients who have undergone thrombectomy for ischemic stroke, and correlated history of migraine with risk of peri-procedural complications. A total of 314 patients underwent thrombectomy at the Danish National Hospital from January 2012 to December 2014. Eligible subjects were phone-interviewed using a purpose-developed semi-structured questionnaire according to the International Classification of Headache Disorders 3, beta version criteria. Among 96 eligible subjects, there was a significant decrease in migraine (p = 0.022) within the first 3 months after EVT compared to 1 year before treatment, which was further evident at interview time (on average 1.6 years after EVT, p = 0.013). A minority of patients experienced headaches for the first time within 3 months of their EVT (migraine 2, TTH 9), which persisted at interview time for subjects with migraine. Out of 12 subjects with peri-procedural complications, 2 had a history of migraine with aura. Thrombectomy leads to a significant decrease in previously known migraine, and new onset of headache in a small subset of patients. A history of migraine does not appear to predispose to peri-procedural complications.

  12. Endovascular treatment of acute limb ischemia and proximal deep vein thrombosis using rotational thrombectomy: A review of published literature.

    PubMed

    Lichtenberg, Michael; Stahlhoff, Friedrich-Wilhelm; Boese, Dirk

    2013-01-01

    Acute and subacute ischemia of the lower extremity is still a common reason for amputation. The treatment of this condition includes the well known procedure of local thrombolysis, surgical thrombectomy and, in recent times, percutaneous mechanical thrombectomy procedures such as rotational thrombectomy. However, in randomized studies Fogarty's procedure of surgical thrombectomy was associated with a high rate of perioperative complications and, in part, low technical success rates. On the other hand, local thrombolysis is associated with hemorrhage as well as high costs because of measures requiring substantial resources, such as intensive care monitoring or repeat angiographies. In several studies, the endovascular therapy options of Straub Rotarex® and Aspirex® systems, both products of technical advancements in the field, were shown to be successful in terms of amputation-free survival. Their use was also associated with low complication rates. The majority of studies were focused on arterial blood flow in the femur. However, in the meantime several registers and studies have shown that the systems can also be effectively used to treat proximal deep vein thrombosis. In the present report we review the current study-based value of rotational thrombectomy in the venous and arterial system.

  13. Surgical thrombectomy for thrombosed dialysis grafts: comparison of adjunctive treatments.

    PubMed

    Liu, Yun-Hen; Hung, Yen-Ni; Hsieh, Hung-Chang; Ko, Po-Jen

    2008-02-01

    Vascular surgeons often encounter dialysis graft failure in hemodialysis patients during their daily practice. Despite advances in percutaneous treatment, there remains a role for surgical thrombectomy of thrombosed dialysis grafts. This study was designed to investigate the long-term outcome of dialysis graft thrombectomy and to examine the indications for and effectiveness of therapies adjuvant to Fogarty thrombectomy. Surgical outcomes of 590 consecutive dialysis graft thrombectomies performed between 2001 and 2003 were retrospectively reviewed. The 590 cases were classified into four groups based on the procedure performed adjuvant to Fogarty thrombectomy: group A, surgical thrombectomy by Fogarty thrombectomy catheter alone; group B, thrombectomy plus intraoperative angioplasty of graft outlet; group C, thrombectomy plus sequential balloon angioplasty in subsequent intervention; group D, thrombectomy plus graft outlet surgical revision. Age, gender, co-morbidity, and primary patency of grafts were reviewed and analyzed. The four groups exhibited similar demographic features and comorbidities (p>0.05). Mean primary patency in the four groups was 1.99+/-4.02, 7.21+/-7.61, 8.35+/-9.53, and 7.26+/-6.99 (months), respectively. Survival curves for each group were determined by Kaplan-Meier methods. Primary patency in group A was statistically inferior to all of the other three groups, whereas groups B, C, and D did not significantly differ with regard to graft patency. Surgical thrombectomy alone is inadequate for treating a thrombosed dialysis graft. The underlying graft outlet stricture requires direct surgical revision or balloon angioplasty during surgery or intervention in the angiography suite to ensure long-term patency of the graft.

  14. Right atrial thrombi: Percutaneous mechanical thrombectomy

    SciTech Connect

    Beregi, Jean-Paul; Aumegeat, Valerie; Loubeyre, Christophe; Coullet, Jean-Michel; Asseman, Philippe; Debacker-Steckelorom, Caroline; Bauchart, Jean-Jacques; Liu Pengcheng; Thery, Claude

    1997-03-15

    The current therapeutic options for right atrial thrombi-surgical embolectomy and thrombolysis- are associated with high mortality and such patients often have contraindications to these therapeutic options. the purpose of this study was to evaluate the feasibility of endovascular right atrial embolectomy. Two patients with contraindications to thrombolysis and surgery were treated by a femoral approach. A catheter was placed in the right atrium, under fluoroscopic control, and a basket device was used to trap the thrombus. The location and extent of the thrombus was established before the procedure by transesophageal echocardiography (TEE) and the procedure was performed with TEE and fluoroscopy. Thrombi were withdrawn in the basket into the inferior vena cava (IVC) and a filter was inserted by a jugular approach and positioned in the IVC, just above the thrombi. The basket was removed leaving the thrombus below the filter. One patient died immediately after the procedure. In conclusion, endovascular extraction of right atrial thrombi may represent a potential therapeutic alternative, particularly in patients with contraindications to thrombolysis and surgery.

  15. [Thrombectomy and plication of veins as a method of preventing pulmonary artery thromboembolism at a multidisciplinary surgical hospital].

    PubMed

    Galkin, S V; Pashin, N V; Dedyukhin, I G; Aleksandrov, A G; Lebedeva, M V

    2016-01-01

    The authors assessed efficacy and safety of the operation of plication of deep veins of lower extremities, pelvic veins, and the inferior vena cava as a method of preventing fatal pulmonary artery thromboembolism. A total of 48 patients were operated on. Of these, 23 patients belonged to traumatological-and-orthopaedical cohort, 3 to general surgical cohort, 4 to gynaecological, and 18 to vascular cohort (isolated deep vein thrombosis). The length of the floating head of the thrombus varied from 2 to 10 cm. The presence of a floating thrombus in traumatological, surgical and gynaecological patients, regardless of the length of the floating part was an absolute indication for thrombectomy and venous plication. Vascular patients were operated on in accordance with the National Guidelines (with the length of the thrombus floating portion of not less than 4 cm). In all cases, surgical management envisaged direct and indirect thrombectomy. Plication was always performed above the level of venotomy. It was shown that thrombectomy combined with plication of major veins is a reliable and safe method of prophylaxis, being in some cases the only possible method of preventing fatal pulmonary artery thromboembolism. The operation of plication makes it possible not to cancel a scheduled surgical intervention in patients with a detected floating thrombus of major veins. The operation of thrombectomy and plication above the level of the floating head of the thrombus may be considered an operation of choice in the conditions where there is no possibility to use endovascular methods of treatment (implantation of a cava filter, endovascular catheter thrombectomy), as well as in pregnant women. Restoration of the venous lumen occurs at safe terms spontaneously, not requiring repeat surgical intervention. Simultaneous plication of the vein does not complicate the course of the postoperative period of the main surgical intervention. Thrombectomy and plication do not lead to the

  16. Successful Manual Aspiration Thrombectomy in a Pediatric Patient.

    PubMed

    Weiner, Gregory M; Feroze, Rafey A; Agarwal, Nitin; Panczykowski, David M; Ares, William J; Kooshkabadi, Ali; Cummings, Dana D; Carson, Vincent; Aghaebrahim, Amin; Jankowitz, Brian T

    2016-08-01

    Timely recognition of stroke at major pediatric medical centers is improving, and although treatment guidelines for pediatric stroke exist, no extensive study establishing the efficacy of surgical or thrombolytic treatment has been completed. Extrapolation of adult guidelines to pediatric patients remains the mainstay of treatment in the absence of adequate information regarding safety and efficacy in children. Recent trials have demonstrated revascularization and clinical improvement after endovascular retrieval therapy in adults with acute large vessel occlusive stroke. Furthermore, successful mechanical thrombectomy using a variety of techniques has been documented in numerous children and adolescents. We present a 15-year-old boy with altered mental status and left hemiparesis due to acute ischemic stroke secondary to blockage of the right internal carotid artery terminus, most likely precipitated by end-stage heart failure and cardiac embolism. Mechanical aspiration thrombectomy using the Penumbra aspiration catheter without any adjunct surgical equipment or thrombolytic therapy was used to remove thrombus and treat the patient's acute ischemic stroke. He experienced complete artery recanalization with a Thrombolysis in Cerebral Infarction (TICI) score of 2C after the procedure. He also exhibited an 8 point improvement in his pediatric National Institutes of Health Stroke Scale score within 24 hours. Mechanical aspiration thrombectomy is commonly used in adult hospitals but infrequently employed in pediatric patients with arterial ischemic stroke. Given its efficacy in our patient, we encourage a larger systematic trial to evaluate the use of mechanical thrombectomy in pediatric patients with acute ischemic stroke. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Safety and Efficacy of Solitaire Stent Thrombectomy

    PubMed Central

    Campbell, Bruce C.V.; Hill, Michael D.; Rubiera, Marta; Menon, Bijoy K.; Demchuk, Andrew; Donnan, Geoffrey A.; Roy, Daniel; Thornton, John; Dorado, Laura; Bonafe, Alain; Levy, Elad I.; Diener, Hans-Christoph; Hernández-Pérez, María; Pereira, Vitor Mendes; Blasco, Jordi; Quesada, Helena; Rempel, Jeremy; Jahan, Reza; Davis, Stephen M.; Stouch, Bruce C.; Mitchell, Peter J.; Jovin, Tudor G.; Saver, Jeffrey L.

    2016-01-01

    Background and Purpose— Recent positive randomized trials of endovascular therapy for ischemic stroke used predominantly stent retrievers. We pooled data to investigate the efficacy and safety of stent thrombectomy using the Solitaire device in anterior circulation ischemic stroke. Methods— Patient-level data were pooled from trials in which the Solitaire was the only or the predominant device used in a prespecified meta-analysis (SEER Collaboration): Solitaire FR With the Intention for Thrombectomy as Primary Endovascular Treatment (SWIFT PRIME), Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion With Emphasis on Minimizing CT to Recanalization Times (ESCAPE), Extending the Time for Thrombolysis in Emergency Neurological Deficits—Intra-Arterial (EXTEND-IA), and Randomized Trial of Revascularization With Solitaire FR Device Versus Best Medical Therapy in the Treatment of Acute Stroke Due to Anterior Circulation Large Vessel Occlusion Presenting Within Eight Hours of Symptom Onset (REVASCAT). The primary outcome was ordinal analysis of modified Rankin Score at 90 days. The primary analysis included all patients in the 4 trials with 2 sensitivity analyses: (1) excluding patients in whom Solitaire was not the first device used and (2) including the 3 Solitaire-only trials (excluding ESCAPE). Secondary outcomes included functional independence (modified Rankin Score 0–2), symptomatic intracerebral hemorrhage, and mortality. Results— The primary analysis included 787 patients: 401 randomized to endovascular thrombectomy and 386 to standard care, and 82.6% received intravenous thrombolysis. The common odds ratio for modified Rankin Score improvement was 2.7 (2.0–3.5) with no heterogeneity in effect by age, sex, baseline stroke severity, extent of computed tomography changes, site of occlusion, or pretreatment with alteplase. The number needed to treat to reduce disability was 2.5 and for an extra patient to achieve independent

  18. Vessel wall signal enhancement on 3-T MRI in acute stroke patients after stent retriever thrombectomy.

    PubMed

    Abraham, Peter; Scott Pannell, J; Santiago-Dieppa, David R; Cheung, Vincent; Steinberg, Jeffrey; Wali, Arvin; Gupta, Mihir; Rennert, Robert C; Lee, Roland R; Khalessi, Alexander A

    2017-04-01

    OBJECTIVE In vivo and in vitro studies have demonstrated histological evidence of iatrogenic endothelial injury after stent retriever thrombectomy. However, noncontrast vessel wall (VW)-MRI is insufficient to demonstrate vessel injury. Authors of this study prospectively evaluated iatrogenic endothelial damage after stent retriever thrombectomy in humans by utilizing high-resolution contrast-enhanced VW-MRI. Characterization of VW-MRI changes in vessels subject to mechanical injury from thrombectomy may allow better understanding of the biological effects of this intervention. METHODS The authors prospectively recruited 11 patients for this study. The treatment group included 6 postthrombectomy patients and the control group included 5 subjects undergoing MRI for nonvascular indications. All subjects were evaluated on a Signa HD× 3.0-T MRI scanner with an 8-channel head coil. Both pre- and postcontrast T1-weighted Cube VW images as well as MR angiograms were acquired. Sequences obtained for evaluation of the brain parenchyma included diffusion-weighted, gradient echo, and T2-FLAIR imaging. Two independent neuroradiologists, who were blinded to the treatment status of each patient, determined the presence of VW enhancement. Patient age, National Institutes of Health Stroke Scale score on presentation, location of occlusion, stroke etiology, type of device used, number of device deployments, Thrombolysis in Cerebral Infarction (TICI) reperfusion score, stroke volume, and 90-day modified Rankin Scale score were also noted. RESULTS Postcontrast T1-weighted VW enhancement was detected in the M2 segment in 100% of the thrombectomy patients, in the M1 segment in 83%, and in the internal carotid artery in 50%. One patient also demonstrated A1 segment enhancement, which was attributable to thrombectomy treatment of that vessel segment during the same procedure. None of the control patients demonstrated VW enhancement of their intracranial vasculature on T1-weighted images

  19. A novel fluoroscopic-assisted balloon thrombectomy technique for thrombosed hemodialysis prosthetic grafts [corrected].

    PubMed

    Kakkos, Stavros K; Haddad, Joseph A; Haddad, Georges K

    2010-01-01

    Previous studies have shown that stenosis of the arterial anastomosis of thrombosed hemodialysis (HD) grafts, unmasked after conventional thrombectomy, very often necessitate subsequent arterial angioplasty. The aim of this study was to describe a novel fluoroscopic-assisted balloon thrombectomy technique which permits simultaneous arterial angioplasty (should this is required) for thrombosed HD grafts. Thirty patients with 36 thrombotic episodes of their prosthetic HD grafts participated in this study. A balloon angioplasty catheter is placed beyond the arterial anastomosis, over a guidewire; the balloon is inflated with contrast solution under fluoroscopy and pulled back to remove the arterial thrombus from the anastomosis. Any coexisting stenosis revealed by balloon indentation is completely dilated at that time, rather than after the thrombectomy. Mechanical thrombolysis of the graft and venous outflow is then performed with the AngioJet catheter (Possis Medical, Inc). Technical and clinical success rates (the latter defined as one subsequent HD session) of the procedure were 100% and 94%, respectively. No complications, including arterial embolism, vessel rupture or pulmonary embolism, were encountered. Primary assisted patency at 3 and 6 months was 51% and 32%, respectively, while functional secondary patency at the same follow-up points was 78%. Our technique is safe and also effective in both short- and long-term follow-up. Because it offers convenience, since the treatment of arterial anastomotic stenoses is accomplished in one (rather than two) steps, this method deserves further investigation.

  20. [RADICAL LAPAROSCOPIC NEPHRECTOMY WITH INFERIOR VENA CAVA THROMBECTOMY].

    PubMed

    Perlin, D V; Aleksandrov, I V; Zipunnikov, V P; Ljaljuev, A M

    2015-01-01

    Laparoscopic radical nephrectomy has proven itself as the "gold standard" treatment of renal cell carcinoma. Inferior vena cava (IVC) tumor thrombus is a complicating factor that occurs in 5% to 10% of patients with renal cell carcinoma. In world literature, there are only anecdotal reports on using laparoscopic approach for IVC thrombectomy in patients with renal cell carcinoma. Herein we report our experience of laparoscopic radical nephrectomy and thrombectomy of the level II tumor thrombus in the IVC. Two patients (79-year-old female and 48-year-old male) underwent radical nephrectomy with thrombectomy from IVC for renal cell carcinoma T3bNxM0 complicated by the formation of a tumor thrombus in the IVC. To do this, IVC was isolated, the right gonadal and lumbar veins were ligated and transected. The IVC and the left renal vein blood flow were controlled with a plastic clip and Satinski clamp. After thrombectomy and resection of the IVC, the wall the defect was sutured with continuous Prolene suture. Laparoscopic radical nephrectomy with thrombectomy without conversion to open surgery was successfully carried out in both patients. During 6-18 months follow-up no local recurrence or distant metastasis were observed. Laparoscopic radical nephrectomy with thrombectomy for renal cell carcinoma complicated with tumor thrombus level II is a safe and reproducible method, which can be applied to a specific population of patients.

  1. Transverse rupture of ring-supported Dacron graft 10 years after axillobifemoral artery bypass: induced by graft deterioration and Fogarty thrombectomy.

    PubMed

    Miyake, Keisuke; Sakagoshi, Nobuo; Kitabayashi, Katsukiyo

    2016-12-01

    A 70-year-old woman underwent an axillobifemoral artery bypass using a bifurcated ring-supported Dacron graft in 2004 and then noticed a pulsatile mass in the left flank 10 years later. A Fogarty thrombectomy was performed for acute graft occlusion. Eight months later, computed tomography revealed pseudoaneurysm formation in the graft body and surgical graft interposition was performed. The operative findings showed a transverse rupture of the graft just above the bifurcation. Histological findings revealed graft deterioration with filaments broken off from the graft. Although the cause of pseudoaneurysm formation was not apparent, the combination of graft deterioration and additional damage from the Fogarty thrombectomy was highly suspicious.

  2. Catheter directed lysis and thrombectomy of submassive pulmonary embolism.

    PubMed

    Krichavsky, Marc Z; Rybicki, Frank J; Resnic, Frederic S

    2011-01-01

    Acute pulmonary embolism (PE) is a common and potentially highly morbid disease. However, there are a broad range of clinical presentations, varying from asymptomatic to life-threatening hemodynamic compromise. Accordingly, the aggressiveness of treatment for acute PE must be adjusted to the acuity of the presentation and patient-specific comorbidities. Thrombolysis is FDA approved for massive PE with hemodynamic compromise. However, this therapy has associated risk, most notably intracranial hemorrhage and other bleeding complications. This has prompted interest in catheter-directed therapies to mechanically remove thrombus and to locally deliver reduced doses of thrombolytics. Guidelines support use of this catheter-based strategy in cases of increased bleeding risk or high acuity with insufficient time for systemic pharmacologic therapy to be effective. We present the case of an 83-year-old man with acute high-risk PE and worsening hemodynamic and respiratory status who was treated with catheter-directed thrombolysis and rheolytic thrombectomy. There was significant improvement in thrombus burden, symptoms, and hemodynamic parameters including right ventricular function and pulmonary artery pressures. However, his course was complicated by intracranial hemorrhage and access site hematoma, demonstrating that even reduced doses and local delivery of thrombolytics do not ensure freedom from bleeding complications.

  3. Aspirex Thrombectomy in Occluded Dialysis Access: A Retrospective Study.

    PubMed

    Dyer, Jules; Rosa, Joao; Chachlani, Menka; Nicholas, Johann

    2016-10-01

    This study is the first to present the outcomes of the Straub Aspirex device for the salvage of occluded renal dialysis access fistulae. This is a retrospective study, using data from the Renal Unit and Radiology Department database. It included all the patients between 2010 and 2014 who underwent percutaneous mechanical thrombectomy (PMT) treated by JD. Aspirex is an over-the-wire, 6-10 French catheter within which is a rapidly rotating helix which draws thrombus into a window near the tip which it then macerates and removes. Access survival was assessed using the Kaplan-Meier method, and multi-variant analysis was performed using the Cox proportional hazards model. Significance was considered if p < 0.05. A total of 27 procedures were performed for 19 patients. 13 had autologous arterio-venous fistulae, and 14 had synthetic (PTFE) arterio-venous grafts. 15 were males, 4 females. 100 % of the patients successfully had a channel of thrombus removed. This resulted in an 81.5 % initial clinical success, with primary patency rates of 53.6, 44.3 and 33 % by days 30, 90 and 480, respectively, without significant difference of any analysed covariates. No major complication (pulmonary embolus, paradoxical cerebral infarction, limb ischaemia or significant haemorrhage) occurred. Aspirex has rates of patency and complication similar to other PMT devices. No covariant studied affected outcome.

  4. AngioJet Thrombectomy for Occluded Dialysis Fistulae: Outcome Data

    SciTech Connect

    Littler, Peter Cullen, Nicola; Gould, Derek; Bakran, Ali; Powell, Steven

    2009-03-15

    This study evaluates AngioJet thrombectomy of occluded autogenous dialysis fistulae and polytetrafluoroethylene (PTFE) grafts in a UK hemodialysis population. Comparison is made with published data of alternative percutaneous thrombectomy methods. All patients with occluded dialysis fistulae who sought care at the Royal Liverpool University Hospital between October 2006 and June 2008 were included in the study. All patients were treated with the AngioJet Rheolytic Thrombectomy Device (Possis, Minneapolis, MN). Demographics, time of occlusion, adjunctive therapies, complications, and follow-up data have been prospectively recorded. A total of 64 thrombectomy procedures were performed in 48 patients. Forty-four autogenous fistulas were treated in 34 patients (19 brachiocephalic, 8 radiocephalic, and 7 transposed brachiobasilic). Twenty PTFE grafts were treated in 14 patients (9 brachioaxillary, 3 brachiocephalic loop grafts, 1 brachiobasilic, and 1 femoro-femoral). The average length of occlusion was 24 cm. Average time to intervention was 4 days. Immediate primary patency was 91%. Primary patency at 1, 3, and 6 months, respectively, was 71%, 60%, and 37%. Secondary patency at 3, 6, and 12 months was 87%, 77%, and 62%, respectively. Angioplasty was carried out in all procedures. Patients required stent insertion in 34 of the 64 thrombectomies to treat angioplasty-resistant stenoses. Complications included a puncture-site hematoma, and three angioplasty-related vein ruptures in one patient, all treated with covered stent grafts. Two cases of distal brachial arterial embolization were successfully treated by thrombosuction. AngioJet thrombectomy in dialysis access occlusion is safe and effective, comparing favorably with other methods.

  5. Combined mechanical loading of composite tubes

    NASA Technical Reports Server (NTRS)

    Derstine, Mark S.; Pindera, Marek-Jerzy; Bowles, David E.

    1988-01-01

    An analytical/experimental investigation was performed to study the effect of material nonlinearities on the response of composite tubes subjected to combined axial and torsional loading. The effect of residual stresses on subsequent mechanical response was included in the investigation. Experiments were performed on P75/934 graphite-epoxy tubes with a stacking sequence of (15/0/ + or - 10/0/ -15), using pure torsion and combined axial/torsional loading. In the presence of residual stresses, the analytical model predicted a reduction in the initial shear modulus. Experimentally, coupling between axial loading and shear strain was observed in laminated tubes under combined loading. The phenomenon was predicted by the nonlinear analytical model. The experimentally observed linear limit of the global shear response was found to correspond to the analytically predicted first ply failure. Further, the failure of the tubes was found to be path dependent above a critical load level.

  6. A New Rotational Thrombectomy Catheter: System Design and First Clinical Experiences

    SciTech Connect

    Schmitt, Hans-Erich; Jaeger, Kurt A.; Jacob, Augustinus L.; Mohr, Helmuth; Labs, Karl-Heinz; Steinbrich, Wolfgang

    1999-11-15

    Purpose: To describe a new catheter for the percutaneous mechanical removal of fresh and organized thrombi, and to assess its efficacy and safety in vitro and in vivo. Methods: The catheter consists of a coated stainless steel spiral that rotates at 40,000 rpm over a guidewire inside the whole length of an 8 Fr, single-lumen, polyurethane catheter, driving a dual-blade cutting crown. Abraded occlusion material is sucked into the catheter head through distal side holes and transported by the spiral into a reservoir at the proximal end. The efficacy of the device was tested in arterial models and fresh bovine carotid arteries (n = 72). In a clinical pilot study 10 patients (8 women, 2 men; mean age 70.6 {+-} 10.1 years) with occlusions of the superficial femoral artery (2-12 cm, mean 5.8 cm), not older than 4 weeks, underwent thrombectomy with the new catheter. Results: In arterial models and bovine cadaver arteries the catheter completely removed fresh thrombi. Occlusion material of higher consistency was cut into particles of 100-500 {mu}m and transported outside. Thrombectomy was successful and vessel patency restored in all 10 patients. The ankle/brachial pressure index significantly (p < 0.0005) increased from 0.41 {+-} 0.18 before intervention to 0.88 {+-} 0.15 after 48 hr and to 0.84 {+-} 0.20 after 3 months. Two reocclusions occurred within 14 days after the intervention. Conclusion: Thrombectomy with the new device appears to be feasible and safe in patients with acute and subacute occlusions of the femoropopliteal artery.

  7. [Percutaneous rheolytic thrombectomy in the treatment of high-risk acute pulmonary embolism: Initial experience of a single center].

    PubMed

    Faria, Rita; Oliveira, Márcia; Ponte, Marta; Pires-Morais, Gustavo; Sousa, Marta; Fernandes, Paula; Rodrigues, Alberto; Braga, Pedro; Gonçalves, Manuel; Gama, Vasco

    2014-06-01

    For years, the treatment of high-risk pulmonary embolism (PE) was based on two well-defined strategies: thrombolysis, whose benefits have been documented in randomized trials, and surgical embolectomy. However, mechanical reperfusion by percutaneous techniques is used in an increasing number of patients, and is a valid therapeutic option when there is a formal contraindication to thrombolysis, as rescue therapy when thrombolysis fails to improve hemodynamics, and/or when emergency surgical thrombectomy is unavailable or contraindicated. This article discusses the indications for the use of percutaneous techniques in PE, reports the initial experience of our center with the AngioJet® thrombectomy device (Possis Medical Inc, Minneapolis, MN, USA) and reviews the available evidence, the most recent recommendations and the main complications associated with this procedure. Copyright © 2013 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

  8. Balloon catheter dilatation and thrombectomy for acute aortoiliac occlusion

    PubMed Central

    Archie, Joseph P.

    1981-01-01

    A case of acute distal aortic thrombosis in an elderly high-risk patient was successfully managed with intraoperative thrombectomy and balloon catheter dilatation of the common iliac arteries. Balloon catheter dilatation may be indicated prior to bypass grafting in high-risk patients with acute aortoiliac thrombosis. PMID:15216181

  9. Guidewire-Controlled Advancement of the Amplatz Thrombectomy Device

    SciTech Connect

    Mueller-Huelsbeck, Stefan; Schwarzenberg, Helmut; Heller, Martin

    1998-01-15

    The Amplatz Thrombectomy Device (ATD) is a percutaneous rotational catheter proven to homogenize thrombus. The catheter design allows neither application over a coaxial running guidewire nor the use of the device as a monorail system. We report a technical modification that provides guided advancement of the catheter over a wire in order to prevent failure of application and to facilitate the interventional procedure.

  10. Isolated pharmacomechanical thrombectomy for the management of chronic DVT.

    PubMed

    Pappy, Reji; Hanna, Elias B; Abu-Fadel, Mazen S; Hennebry, Thomas A

    2011-02-01

    Thrombo-reduction in the setting of deep vein thrombosis (DVT) to prevent the postthrombotic syndrome has not been traditionally managed by interventional cardiologists. We report a case series of successful chronic DVT management with pharmacomechanical thrombectomy utilizing the Trellis device. ©2010, Wiley Periodicals, Inc.

  11. Endovascular thrombectomy with or without systemic thrombolysis?

    PubMed

    Tsivgoulis, Georgios; Katsanos, Aristeidis H; Mavridis, Dimitris; Alexandrov, Anne W; Magoufis, Georgios; Arthur, Adam; Caso, Valeria; Schellinger, Peter D; Alexandrov, Andrei V

    2017-03-01

    Current recommendations advocate that pretreatment with intravenous thrombolysis (IVT) should first be offered to all eligible patients with emergent large vessel occlusion (ELVO) before an endovascular thrombectomy (ET) procedure. However, there are observational data that question the safety and efficacy of IVT pretreatment in patients with ELVO. We performed a meta-analysis of the included subgroups from ET randomized controlled trials (RCTs) to evaluate the comparative efficacy between direct ET without IVT pretreatment and bridging therapy (IVT and ET) in patients with ELVO. We included a total of seven RCTs, including 1764 patients with ELVO (52.8% men). Patients receiving bridging therapy (IVT followed by ET) had lower rates (p = 0.041) of 90-day death/severe dependency (modified Rankin Scale-score of 5-6; 19.0%, 95% CI: 14.1-25.1%) compared with patients receiving only ET (31.0%, 95% CI: 21.2-42.9%). Moreover, patients receiving IVT and ET had a nonsignificant (p = 0.389) trend towards higher 90-day functional independence rates (51.4%, 95% CI: 42.5-60.1%) compared with patients undergoing only ET (41.7%, 95% CI: 24.1-61.7%). Finally, shift-analysis uncovered a nonsignificant trend towards functional improvement at 90 days for bridging therapy over ET (cOR = 1.28, 95% CI: 0.91-1.89; p = 0.155). It should be noted that patients included in the present meta-analysis were not randomized to receive IVT, and thus the two groups (bridging therapy versus ET monotherapy) may differ in terms of baseline characteristics and, in particular, in terms of onset to groin puncture time and thus the risk of confounding bias cannot be ruled out. Despite the limitations and the risk of confounding bias, our findings contradict the recent notion regarding potential equality between ET and bridging therapy in ELVO patients and suggest that IVT and ET are complementary therapies that should be pursued in a parallel and noncompeting fashion.

  12. Catheter-Directed Thrombolysis with Percutaneous Rheolytic Thrombectomy Versus Thrombolysis Alone in Upper and Lower Extremity Deep Vein Thrombosis

    SciTech Connect

    Kim, Hyun S. Patra, Ajanta; Paxton, Ben E.; Khan, Jawad; Streiff, Michael B.

    2006-12-15

    Purpose. To compare the efficacy of catheter-directed thrombolysis (CDT) alone versus CDT with rheolytic percutaneous mechanical thrombectomy (PMT) for upper and lower extremity deep vein thrombosis (DVT). Methods. A retrospective cohort of consecutive patients with acute iliofemoral or brachiosubclavian DVT treated with urokinase CDT was identified, and a chart review was conducted. Demographic characteristics, treatment duration, total lytic dose, clot lysis rates and complications were compared in patients treated with urokinase CDT alone or combined CDT and rheolytic PMT. Results. Forty limbs in 36 patients were treated with urokinase CDT alone. Twenty-seven limbs in 21 patients were treated with urokinase CDT and rheolytic PMT. The mean treatment duration for urokinase CDT alone was 48.0 {+-} 27.1 hr compared with 26.3 {+-} 16.6 hr for urokinase CDT and rheolytic PMT (p = 0.0004). The mean urokinase dose required for CDT alone was 5.6 {+-} 5.3 million units compared with 2.7 {+-} 1.8 million units for urokinase CDT with rheolytic PMT (p = 0.008). Complete clot lysis was achieved in 73% (29/40) of DVT treated with urokinase CDT alone compared with 82% (22/27) treated with urokinase CDT with rheolytic PMT. Conclusion. Percutaneous CDT with rheolytic PMT is as effective as CDT alone for acute proximal extremity DVT but requires significantly shorter treatment duration and lower lytic doses. Randomized studies to confirm the benefits of pharmacomechanical thrombolysis in the treatment of acute proximal extremity DVT are warranted.

  13. Third nerve palsy following carotid artery dissection and posterior cerebral artery thrombectomy: Case report and review of the literature

    PubMed Central

    Kogan, Michael; Natarajan, Sabareesh K.; Kim, Nina; Sawyer, Robert N.; Snyder, Kenneth V.; Siddiqui, Adnan H.

    2014-01-01

    Background: Common causes of oculomotor nerve palsy are diabetes, aneurysmal compression, and uncal herniation. A lesser-known cause of third nerve dysfunction is ischemia, often due to carotid artery dissection. Case Description: An 80-year-old man presented with an acute ischemic stroke with a National Institutes of Health Stroke Scale score of >20 from a high cervical internal carotid artery (ICA) dissection and a tandem ICA terminus embolic occlusion with extension of clot into the adjacent fetal posterior cerebral artery (PCA). We used a stentriever to perform selective PCA thrombectomy, with immediate postthrombectomy development of ipsilateral anisocoria. The anisocoria progressed into complete oculomotor nerve palsy over 8 h after the procedure. Conclusions: The clinical course described in this case is consistent with injury to the third nerve due to mechanical injury or occlusion of perforator supply to the nerve during thrombectomy. Oculomotor nerve palsy is a rare but known complication after ischemia; however, to our knowledge, this is the first case after thrombectomy for a PCA embolus. PMID:25525555

  14. Prototype fabrication and preliminary in vitro testing of a shape memory endovascular thrombectomy device.

    PubMed

    Small, Ward; Wilson, Thomas S; Buckley, Patrick R; Benett, William J; Loge, Jeffrey M; Hartman, Jonathan; Maitland, Duncan J

    2007-09-01

    An electromechanical microactuator comprised of shape memory polymer (SMP) and shape memory nickel-titanium alloy (nitinol) was developed and used in an endovascular thrombectomy device prototype. The microactuator maintains a straight rod shape until an applied current induces electro-resistive (Joule) heating, causing the microactuator to transform into a corkscrew shape. The straight-to-corkscrew transformation geometry was chosen to permit endovascular delivery through (straight form) and retrieval of (corkscrew form) a stroke-causing thrombus (blood clot) in the brain. Thermal imaging of the microactuator during actuation in air indicated that the steady-state temperature rise caused by Joule heating varied quadratically with applied current and that actuation occurred near the glass transition temperature of the SMP (86 degrees C). To demonstrate clinical application, the device was used to retrieve a blood clot in a water-filled silicone neurovascular model. Numerical modeling of the heat transfer to the surrounding blood and associated thermal effects on the adjacent artery potentially encountered during clinical use suggested that any thermal damage would likely be confined to localized areas where the microactuator was touching the artery wall. This shape memory mechanical thrombectomy device is a promising tool for treating ischemic stroke without the need for infusion of clot-dissolving drugs.

  15. AUTOPSY FINDINGS AFTER INTRACRANIAL THROMBECTOMY for ACUTE ISCHEMIC STROKE: A CLINICOPATHOLOGIC STUDY of FIVE PATIENTS

    PubMed Central

    Yin, Nicole S.; Benavides, Sebastian; Starkman, Sidney; Liebeskind, David S.; Saver, Jeffrey A.; Salamon, Noriko; Jahan, Reza; Duckwiler, Gary R.; Tateshima, Satoshi; Vinuela, Fernando; Vespa, Paul M.; Chute, Dennis J.; Vinters, Harry V.

    2014-01-01

    Background and Purpose Endovascular thrombectomy is an increasingly used treatment for arterial occlusion in acute stroke. Various devices (including most extensively the Mechanical Embolus Removal in Cerebral Ischemia/MERCI Retriever device) have been utilized for this. Methods We review the neuropathologic findings in 5 patients (age range 59–87 years) who died acutely or as late as 38 days after procedures using the Merci (4 patients) and Penumbra (1 patient) devices were carried out to remove thrombo-emboli from the middle cerebral artery (MCA). Partial recanalization was achieved by thrombectomy in all 5 patients. Results All patients showed extensive cerebral infarcts, 3/5 with clinical hemorrhagic transformations of the infarct or frank intraparenchymal hemorrhage after thrombectomy— in one case this was judged to be at least partly on the basis of concomitant hypertensive microvascular disease. With one exception basal arteries examined in detail by immunohistochemistry, showed prominent, though usually non-occlusive (and generally non-ulcerated) atheromata, often with significant luminal stenosis. One patient showed a subintimal dissection with resultant occlusion of the MCA. Conclusions In this highly selected group of patients, the vascular pathologic abnormalities affecting basal arteries were variable, but complicated atherosclerosis was a common finding. Extensive irreversible brain necrosis prior to therapeutic procedures may have contributed to deaths. PMID:20360544

  16. Multi-mechanism vibration harvester combining inductive and piezoelectric mechanisms

    NASA Astrophysics Data System (ADS)

    Marin, Anthony; Priya, Shashank

    2012-04-01

    With increasing demand for wireless sensor nodes in automobile, aircraft and rail applications, the need for energy harvesters has been growing. In these applications, energy harvesters provide a more robust and inexpensive power solution than batteries. In order to enhance the power density of existing energy harvesters, a variety of multimodal energy harvesting techniques have been proposed. Multi-modal energy harvesters can be categorized as: (i) Multi-Source Energy Harvester (MSEH), (ii) Multi-Mechanism Energy Harvester (MMEH), and (iii) Single Source Multi-Mode Energy Harvester (S2M2EH). In this study, we focus on developing MMEH which combines the inductive and piezoelectric mechanisms. The multi-mechanism harvester was modeled using FEM techniques and theoretically analyzed to optimize the performance and reduce the overall shape and size similar to that of AA battery. The theoretical model combining analytical and FEM modeling techniques provides the system dynamics and output power for specific generator and cymbal geometry at various source conditions. In the proposed design, a cylindrical tube contains a magnetic levitation cavity where a center magnet oscillates through a copper coil. Piezoelectric cymbal transducers were mounted on the top and bottom sections of the cylindrical shell. In response to the external vibrations, electrical energy was harvested from the relative motion between magnet and coil through Faraday's effect and from the piezoelectric material through the direct piezoelectric effect. Experimental results validate the predictions from theoretical model and show the promise of multimodal harvester for powering wireless sensor nodes in automobile, aircraft, and rail applications.

  17. Thrombectomy within 8 hours after symptom onset in ischemic stroke.

    PubMed

    Jovin, Tudor G; Chamorro, Angel; Cobo, Erik; de Miquel, María A; Molina, Carlos A; Rovira, Alex; San Román, Luis; Serena, Joaquín; Abilleira, Sonia; Ribó, Marc; Millán, Mònica; Urra, Xabier; Cardona, Pere; López-Cancio, Elena; Tomasello, Alejandro; Castaño, Carlos; Blasco, Jordi; Aja, Lucía; Dorado, Laura; Quesada, Helena; Rubiera, Marta; Hernandez-Pérez, María; Goyal, Mayank; Demchuk, Andrew M; von Kummer, Rüdiger; Gallofré, Miquel; Dávalos, Antoni

    2015-06-11

    We aimed to assess the safety and efficacy of thrombectomy for the treatment of stroke in a trial embedded within a population-based stroke reperfusion registry. During a 2-year period at four centers in Catalonia, Spain, we randomly assigned 206 patients who could be treated within 8 hours after the onset of symptoms of acute ischemic stroke to receive either medical therapy (including intravenous alteplase when eligible) and endovascular therapy with the Solitaire stent retriever (thrombectomy group) or medical therapy alone (control group). All patients had confirmed proximal anterior circulation occlusion and the absence of a large infarct on neuroimaging. In all study patients, the use of alteplase either did not achieve revascularization or was contraindicated. The primary outcome was the severity of global disability at 90 days, as measured on the modified Rankin scale (ranging from 0 [no symptoms] to 6 [death]). Although the maximum planned sample size was 690, enrollment was halted early because of loss of equipoise after positive results for thrombectomy were reported from other similar trials. Thrombectomy reduced the severity of disability over the range of the modified Rankin scale (adjusted odds ratio for improvement of 1 point, 1.7; 95% confidence interval [CI], 1.05 to 2.8) and led to higher rates of functional independence (a score of 0 to 2) at 90 days (43.7% vs. 28.2%; adjusted odds ratio, 2.1; 95% CI, 1.1 to 4.0). At 90 days, the rates of symptomatic intracranial hemorrhage were 1.9% in both the thrombectomy group and the control group (P=1.00), and rates of death were 18.4% and 15.5%, respectively (P=0.60). Registry data indicated that only eight patients who met the eligibility criteria were treated outside the trial at participating hospitals. Among patients with anterior circulation stroke who could be treated within 8 hours after symptom onset, stent retriever thrombectomy reduced the severity of post-stroke disability and increased the

  18. Early middle cerebral artery stenosis following stent-assisted thrombectomy

    PubMed Central

    Akpınar, Süha

    2015-01-01

    Stent-assisted thrombectomy (SAT) is an extensively used endovascular treatment method for stroke in which the thrombectomy stents come into direct contact with the vascular intimal surface and entrap the thrombus causing the arterial occlusion. Although there are a few studies that demonstrate that the vessel wall changes in the arteries where stroke intervention is performed, we observed progressive stenosis in early follow-up imaging studies in a case. We present a middle cerebral artery (MCA) stroke patient who had four repetitive stent passes during SAT and developed distal MCA stenosis 2 months after SAT at the control magnetic resonance angiography (MRA). Inclusion of early follow-up MRA studies would be helpful in defining the silent vascular changes in patients who have undergone repetitive SAT. PMID:26015531

  19. Superior mesenteric venous thrombosis treated by direct aspiration thrombectomy.

    PubMed

    Nakayama, Satoshi; Murashima, Naoya; Isobe, Yoshinori

    2008-01-01

    A 69-year-old man, with hepatits C virus-related liver cirrhosis and hemophilia B, developed massive ascites and watery diarrhea after endoscopic injection sclerotherapy for esophageal varices. A multi detector row computed tomography revealed a superior mesenteric venous thrombus without bowel infarction. It was assumed that the thrombus was caused by transient congestion of the portal system after retrograde propagation of the sclerosant agent, in a condition where anticoagulation proteins, such as proteins C and S, had decreased. Because long systemic thrombolytic therapy was hazardous for the patient with hemorrhagic diathesis due to impaired coagulation, a direct thrombolysis was performed with urokinase followed by aspiration thrombectomy, with cannulation of the portal venous system using a transjugular intrahepatic approach. The patient had no complications in this procedure and subsequently diarrhea and refractory ascites were resolved. Direct thrombectomy via the transjugular intrahepatic route may be a useful therapy for mesenteric venous thrombus in the cirrhotic patient.

  20. Endovascular therapy for acute ischaemic stroke: the Pragmatic Ischaemic Stroke Thrombectomy Evaluation (PISTE) randomised, controlled trial

    PubMed Central

    Muir, Keith W; Ford, Gary A; Messow, Claudia-Martina; Ford, Ian; Murray, Alicia; Clifton, Andrew; Brown, Martin M; Madigan, Jeremy; Lenthall, Rob; Robertson, Fergus; Dixit, Anand; Cloud, Geoffrey C; Wardlaw, Joanna; Freeman, Janet; White, Philip

    2017-01-01

    Objective The Pragmatic Ischaemic Thrombectomy Evaluation (PISTE) trial was a multicentre, randomised, controlled clinical trial comparing intravenous thrombolysis (IVT) alone with IVT and adjunctive intra-arterial mechanical thrombectomy (MT) in patients who had acute ischaemic stroke with large artery occlusive anterior circulation stroke confirmed on CT angiography (CTA). Design Eligible patients had IVT started within 4.5 hours of stroke symptom onset. Those randomised to additional MT underwent thrombectomy using any Conformité Européene (CE)-marked device, with target interval times for IVT start to arterial puncture of <90 min. The primary outcome was the proportion of patients achieving independence defined by a modified Rankin Scale (mRS) score of 0–2 at day 90. Results Ten UK centres enrolled 65 patients between April 2013 and April 2015. Median National Institutes of Health Stroke Scale score was 16 (IQR 13–21). Median stroke onset to IVT start was 120 min. In the intention-to-treat analysis, there was no significant difference in disability-free survival at day 90 with MT (absolute difference 11%, adjusted OR 2.12, 95% CI 0.65 to 6.94, p=0.20). Secondary analyses showed significantly greater likelihood of full neurological recovery (mRS 0–1) at day 90 (OR 7.6, 95% CI 1.6 to 37.2, p=0.010). In the per-protocol population (n=58), the primary and most secondary clinical outcomes significantly favoured MT (absolute difference in mRS 0–2 of 22% and adjusted OR 4.9, 95% CI 1.2 to 19.7, p=0.021). Conclusions The trial did not find a significant difference between treatment groups for the primary end point. However, the effect size was consistent with published data and across primary and secondary end points. Proceeding as fast as possible to MT after CTA confirmation of large artery occlusion on a background of intravenous alteplase is safe, improves excellent clinical outcomes and, in the per-protocol population, improves disability

  1. Retrievable stent thrombectomy in the treatment of acute ischemic stroke: analysis of a revolutionizing treatment technique.

    PubMed

    Walcott, Brian P; Boehm, Kevin M; Stapleton, Christopher J; Mehta, Brijesh P; Nahed, Brian V; Ogilvy, Christopher S

    2013-10-01

    Acute ischemic stroke resulting from intracranial vessel occlusion is associated with high morbidity and mortality. The mainstays of therapy are fibrinolytics and mechanical thrombectomy in properly selected patients. A new Food and Drug Administration-approved technology to perform thrombectomy, retrievable stenting, may provide superior revascularization rates and improved patient outcomes. We analyzed the cumulative human experience reported for the Trevo Pro Retrieval System (Stryker, Kalamazoo, MI, USA) and the Solitaire FR Revascularization Device (ev3, Irvine, CA, USA) as the definitive treatment for acute ischemic stroke. A literature search was undertaken to identify studies using the retrievable stents published up to September 2012. Nineteen studies identified a total of 576 patients treated with either the Trevo (n=221) or Solitaire (n=355) devices. Pooled data analysis identified median baseline National Institutes of Health Stroke Scale scores of 18.5 ± 0.289 (standard error of the mean) and 17.9 ± 0.610, and time to recanalization of 53.9 ± 23.6 minutes and 59.0 ± 8.0 minutes for the Trevo and Solitaire groups, respectively. Recanalization was variably defined by individual studies, most commonly achieving at least a thrombolysis in cerebral infarction score of 2a-3 or a thrombolysis in myocardial infarction score of 2-3. Revascularization (83%, 82%), mortality (31%, 14%), hemorrhage (8%, 6%), device complications (5%, 6%), and good patient outcomes (51%, 47%) were found with the Trevo and Solitaire devices, respectively. Preliminary analysis reveals excellent clinical outcomes for retrievable stent technology. This may be attributable to both high rates of revascularization with a relatively short time to perfusion restoration.

  2. Thrombectomy for Acute Stroke in Childhood: A Case Report, Literature Review, and Recommendations.

    PubMed

    Buompadre, Maria Celeste; Andres, Kathleen; Slater, Lee-Anne; Mohseni-Bod, Hadi; Guerguerian, Anne-Marie; Branson, Helen; Laughlin, Suzanne; Armstrong, Derek; Moharir, Mahendranath; deVeber, Gabrielle; Humpl, Tilman; Honjo, Osami; Keshavjee, Shaf; Ichord, Rebecca; Pereira, Vitor; Dlamini, Nomazulu

    2017-01-01

    The updated American Heart Association/American Stroke Association guidelines include recommendation for thrombectomy in certain adult stroke cases. The safety and efficacy of thrombectomy in children are unknown. An 8-year-old girl experienced acute stroke symptoms on two occasions while therapeutically anticoagulated on Novalung. Computed tomography scans showed proximal vessel thrombi, which were retrieved using a Trevo device without hemorrhagic complications. Postprocedural assessment found respective decreases in the National Institutes of Health Stroke Scale score from 10 to 4 and 12 to 7. The indications for treatment and early benefits observed in our case are consistent with other pediatric thrombectomy cases reported. However, publication bias and the heterogeneity of reported cases prevent drawing conclusions about the safety and efficacy of thrombectomy in children. Anticipating that updates to adult stroke guidelines would likely incite stroke providers to consider thrombectomy in children, our institution developed guidelines for thrombectomy before the index patient. Establishing institutional guidelines before considering thrombectomy in children may optimize patient safety.

  3. Combined Hydrophobicity and Mechanical Durability through Surface Nanoengineering

    NASA Astrophysics Data System (ADS)

    Elliott, Paul R.; Stagon, Stephen P.; Huang, Hanchen; Furrer, David U.; Burlatsky, Sergei F.; Filburn, Thomas P.

    2015-04-01

    This paper reports combined hydrophobicity and mechanical durability through the nanoscale engineering of surfaces in the form of nanorod-polymer composites. Specifically, the hydrophobicity derives from nanoscale features of mechanically hard ZnO nanorods and the mechanical durability derives from the composite structure of a hard ZnO nanorod core and soft polymer shell. Experimental characterization correlates the morphology of the nanoengineered surfaces with the combined hydrophobicity and mechanical durability, and reveals the responsible mechanisms. Such surfaces may find use in applications, such as boat hulls, that benefit from hydrophobicity and require mechanical durability.

  4. Combined hydrophobicity and mechanical durability through surface nanoengineering

    DOE PAGES

    Elliott, Paul R.; Stagon, Stephen P.; Huang, Hanchen; ...

    2015-04-08

    This paper reports combined hydrophobicity and mechanical durability through the nanoscale engineering of surfaces in the form of nanorod-polymer composites. Specifically, the hydrophobicity derives from nanoscale features of mechanically hard ZnO nanorods and the mechanical durability derives from the composite structure of a hard ZnO nanorod core and soft polymer shell. Experimental characterization correlates the morphology of the nanoengineered surfaces with the combined hydrophobicity and mechanical durability, and reveals the responsible mechanisms. Such surfaces may find use in applications, such as boat hulls, that benefit from hydrophobicity and require mechanical durability.

  5. Combined Hydrophobicity and Mechanical Durability through Surface Nanoengineering

    PubMed Central

    Elliott, Paul R.; Stagon, Stephen P.; Huang, Hanchen; Furrer, David U.; Burlatsky, Sergei F.; Filburn, Thomas P.

    2015-01-01

    This paper reports combined hydrophobicity and mechanical durability through the nanoscale engineering of surfaces in the form of nanorod-polymer composites. Specifically, the hydrophobicity derives from nanoscale features of mechanically hard ZnO nanorods and the mechanical durability derives from the composite structure of a hard ZnO nanorod core and soft polymer shell. Experimental characterization correlates the morphology of the nanoengineered surfaces with the combined hydrophobicity and mechanical durability, and reveals the responsible mechanisms. Such surfaces may find use in applications, such as boat hulls, that benefit from hydrophobicity and require mechanical durability. PMID:25851026

  6. Combined hydrophobicity and mechanical durability through surface nanoengineering.

    PubMed

    Elliott, Paul R; Stagon, Stephen P; Huang, Hanchen; Furrer, David U; Burlatsky, Sergei F; Filburn, Thomas P

    2015-04-08

    This paper reports combined hydrophobicity and mechanical durability through the nanoscale engineering of surfaces in the form of nanorod-polymer composites. Specifically, the hydrophobicity derives from nanoscale features of mechanically hard ZnO nanorods and the mechanical durability derives from the composite structure of a hard ZnO nanorod core and soft polymer shell. Experimental characterization correlates the morphology of the nanoengineered surfaces with the combined hydrophobicity and mechanical durability, and reveals the responsible mechanisms. Such surfaces may find use in applications, such as boat hulls, that benefit from hydrophobicity and require mechanical durability.

  7. Thrombectomy using a stent retriever with artificially induced vertebral artery vasospasm in a patient with acute basilar artery occlusion: a case report

    PubMed Central

    Kim, Sanghyeon; Choi, Jae-Hyung

    2015-01-01

    An acute basilar artery occlusion is not an uncommon cause of stroke. It represents 6–10% of large vessel strokes and has been associated with poor clinical outcomes. Multimodal treatments have been introduced to recanalise a basilar artery occlusion successfully. However, all mechanical thrombectomy devices are not always usable in an emergent situation. We present a case of basilar artery occlusion treated with a stent retriever assisted by a vertebral artery vasospasm. We attempted thrombectomy with a stent retriever several times. However, the captured thrombus was not pulled out and migrated to the distal basilar artery and posterior cerebral artery due to anterograde flow of the vertebral artery. We carefully advanced the catheter into the distal vertebral artery and generated a vasospasm. The vertebral artery vasospasm reduced the forward flow significantly like a balloon-guided catheter. The thrombus was pulled out with the stent. PMID:26678752

  8. Aspiration Thrombectomy After Intravenous Alteplase Versus Intravenous Alteplase Alone.

    PubMed

    Mocco, J; Zaidat, Osama O; von Kummer, Rüdiger; Yoo, Albert J; Gupta, Rishi; Lopes, Demetrius; Frei, Don; Shownkeen, Harish; Budzik, Ron; Ajani, Zahra A; Grossman, Aaron; Altschul, Dorethea; McDougall, Cameron; Blake, Lindsey; Fitzsimmons, Brian-Fred; Yavagal, Dileep; Terry, John; Farkas, Jeffrey; Lee, Seon Kyu; Baxter, Blaise; Wiesmann, Martin; Knauth, Michael; Heck, Donald; Hussain, Syed; Chiu, David; Alexander, Michael J; Malisch, Timothy; Kirmani, Jawad; Miskolczi, Laszlo; Khatri, Pooja

    2016-09-01

    Thrombectomy, primarily with stent retrievers with or without adjunctive aspiration, provided clinical benefit across multiple prospective randomized trials. Whether this benefit is exclusive to stent retrievers is unclear. THERAPY (The Randomized, Concurrent Controlled Trial to Assess the Penumbra System's Safety and Effectiveness in the Treatment of Acute Stroke; NCT01429350) was an international, multicenter, prospective, randomized (1:1), open label, blinded end point evaluation, concurrent controlled clinical trial of aspiration thrombectomy after intravenous alteplase (IAT) administration compared with intravenous-alteplase alone in patients with large vessel ischemic stroke because of a thrombus length of ≥8 mm. The primary efficacy end point was the percent of patients achieving independence at 90 days (modified Rankin Scale score, 0-2; intention-to-treat analysis). The primary safety end point was the rate of severe adverse events (SAEs) by 90 days (as treated analysis). Patients were randomized 1:1 across 36 centers in 2 countries (United States and Germany). Enrollment was halted after 108 (55 IAT and 53 intravenous) patients (of 692 planned) because of external evidence of the added benefit of endovascular therapy to intravenous-alteplase alone. Functional independence was achieved in 38% IAT and 30% intravenous intention-to-treat groups (P=0.52). Intention-to-treat ordinal modified Rankin Scale odds ratio was 1.76 (95% confidence interval, 0.86-3.59; P=0.12) in favor of IAT. Secondary efficacy analyses all demonstrated a consistent direction of effect toward benefit of IAT. No differences in symptomatic intracranial hemorrhage rates (9.3% IAT versus 9.7% intravenous, P=1.0) or 90-day mortality (IAT: 12% versus intravenous: 23.9%, P=0.18) were observed. THERAPY did not achieve its primary end point in this underpowered sample. Directions of effect for all prespecified outcomes were both internally and externally consistent toward benefit. It is

  9. Endovascular thrombectomy for stroke: current best practice and future goals.

    PubMed

    Campbell, Bruce C V; Donnan, Geoffrey A; Mitchell, Peter J; Davis, Stephen M

    2016-03-01

    Endovascular thrombectomy for large vessel ischaemic stroke substantially reduces disability, with recent positive randomised trials leading to guideline changes worldwide. This review discusses in detail the evidence provided by recent randomised trials and meta-analyses, the remaining areas of uncertainty and the future directions for research. The data from existing trials have demonstrated the robust benefit of endovascular thrombectomy for internal carotid and proximal middle cerebral artery occlusions. Uncertainty remains for more distal occlusions where the efficacy of alteplase is greater, less tissue is at risk and the safety of endovascular procedures is less established. Basilar artery occlusion was excluded from the trials, but with a dire natural history and proof of principle that rapid reperfusion is effective, it seems reasonable to continue treating these patients pending ongoing trial results. There has been no evidence of heterogeneity in treatment effect in clinically defined subgroups by age, indeed, those aged >80 years have at least as great an overall reduction in disability and reduced mortality. Similarly there was no heterogeneity across the range of baseline stroke severities included in the trials. Evidence that routine use of general anaesthesia reduces the benefit of endovascular thrombectomy is increasing and conscious sedation is generally preferred unless severe agitation or airway compromise is present. The impact of time delays has become clearer with description of onset to imaging and imaging to reperfusion epochs. Delays in the onset to imaging reduce the proportion of patients with salvageable brain tissue. However, in the presence of favourable imaging, rapid treatment appears beneficial regardless of the onset to imaging time elapsed. Imaging to reperfusion delays lead to decay in the clinical benefit achieved, particularly in those with less robust collateral flow. The brain imaging options to assess prognosis have

  10. 302 Vessel Wall Enhancement on Magnetic Resonance Imaging After Stent-Retriever Thrombectomy.

    PubMed

    Abraham, Peter; Cheung, Vincent J; Lee, Roland; Pannell, Jeffrey Scott; Gupta, Mihir; Rennert, Robert; Khalessi, Alexander Arash

    2016-08-01

    Animal and in vitro studies have demonstrated histologic iatrogenic endothelial injury after stent-retriever thrombectomy. However, noncontrast vessel wall magnetic resonance imaging (MRI) studies have failed to demonstrate vessel injury. Our prospective study examines iatrogenic endothelial damage after stent-retriever thrombectomy in vivo utilizing high-resolution contrast-enhanced vessel wall MRI (VW-MRI). We evaluated 11 patients, including postthrombectomy and control subjects, on a Signa HDx 3.0-T MRI scanner with an 8-channel head coil. Pre- and postcontrast T1-weighted CUBE vessel wall images and MR angiograms were acquired with attention to the Circle of Willis. Parenchymal imaging included diffusion, susceptibility, and T2 fluid attenuated inversion recovery (FLAIR)-weighted images. The primary end point was vessel wall enhancement, as determined by 2 independent, blinded board-certified neuroradiologists before examination of parenchymal imaging. Additional covariates were age, National Institutes of Health Stroke Scale, level of occlusion, stroke etiology, devices utilized, number of passes required for thrombectomy, TICI reperfusion score, stroke volume, and 90-day modified Rankin Scale (mRS). Post-contrast T1-weighted vessel wall enhancement was detected in the middle cerebral artery (MCA) M2 segment in 100%, the M1 segment in 83%, and the internal carotid artery in 50% of thrombectomy patients. One patient demonstrated A1 segment anterior cerebral artery (ACA) enhancement, and was prospectively identified by both radiologists as having undergone ACA thrombectomy due to embolism during MCA thrombectomy. Postcontrast T1-weighted vessel wall enhancement was detected in 0% of control patients. Our findings suggest that vessel wall injuries incurred during stent-retriever thrombectomy can be detected utilizing contrast-enhanced 3 T VW-MRI. Our results further demonstrate greater endothelial injury when the thrombectomy device is oversized relative to the

  11. Endovascular thrombectomy for acute ischemic stroke in failed intravenous tissue plasminogen activator versus non-intravenous tissue plasminogen activator patients: revascularization and outcomes stratified by the site of arterial occlusions.

    PubMed

    Shi, Zhong-Song; Loh, Yince; Walker, Gary; Duckwiler, Gary R

    2010-06-01

    Intracranial mechanical thrombectomy is a therapeutic option for acute ischemic stroke patients failing intravenous tissue plasminogen activator (IV tPA). We compared patients treated by mechanical embolus removal in cerebral ischemia (MERCI) thrombectomy after failed IV tPA with those treated with thrombectomy alone. We pooled MERCI and Multi MERCI study patients, grouped them either as failed IV tPA or non-IV tPA, and assessed revascularization rates, procedural complications, symptomatic hemorrhage rates, clinical outcomes, and mortality. We also evaluated outcomes stratified by the occlusion site and final revascularization. Among 305 patients, 48 failed, and 257 were ineligible for IV tPA. Nonresponders to IV tPA trended toward a higher revascularization rate (73% versus 63%) and less mortality (27.7% versus 40.1%) and had similar rates of symptomatic hemorrhage and procedural complications. Favorable 90-day outcomes were similar in failed and non-IV tPA patients (38% versus 31%), with no difference according to occlusion site. Among patients failing IV tPA, good outcomes tended to occur more frequently in revascularized patients (47.1% versus 15.4%), although this relationship was attributable solely to middle cerebral artery and not internal carotid artery occlusions, with no difference in mortality. Among IV tPA-ineligible patients, revascularization correlated with good outcome (47.4% versus 4.4%) and less mortality (28.5% versus 59.6%). The risks of hemorrhage and procedure-related complications after mechanical thrombectomy do not differ with respect to previous IV tPA administration. Thrombectomy after IV tPA achieves similar rates of good outcomes, a tendency toward lower mortality, and similar revascularization rates when stratified by clot location. Good outcomes correlate with successful revascularization except with internal carotid artery occlusions in tPA-nonresponders.

  12. Tuning Cell and Tissue Development by Combining Multiple Mechanical Signals.

    PubMed

    Sinha, Ravi; Verdonschot, Nico; Koopman, Bart; Rouwkema, Jeroen

    2017-05-03

    Mechanical signals offer a promising way to control cell and tissue development. It has been established that cells constantly probe their mechanical microenvironment and employ force feedback mechanisms to modify themselves and when possible, their environment, to reach a homeostatic state. Thus, a correct mechanical microenvironment (external forces and mechanical properties and shapes of cellular surroundings) is necessary for the proper functioning of cells. In vitro or in the case of nonbiological implants in vivo, where cells are in an artificial environment, addition of the adequate mechanical signals can, therefore, enable the cells to function normally as in vivo. Hence, a wide variety of approaches have been developed to apply mechanical stimuli (such as substrate stretch, flow-induced shear stress, substrate stiffness, topography, and modulation of attachment area) to cells in vitro. These approaches have not just revealed the effects of the mechanical signals on cells but also provided ways for probing cellular molecules and structures that can provide a mechanistic understanding of the effects. However, they remain lower in complexity compared with the in vivo conditions, where the cellular mechanical microenvironment is the result of a combination of multiple mechanical signals. Therefore, combinations of mechanical stimuli have also been applied to cells in vitro. These studies have had varying focus-developing novel platforms to apply complex combinations of mechanical stimuli, observing the co-operation/competition between stimuli, combining benefits of multiple stimuli toward an application, or uncovering the underlying mechanisms of their action. In general, they provided new insights that could not have been predicted from previous knowledge. We present here a review of several such studies and the insights gained from them, thereby making a case for such studies to be continued and further developed.

  13. SIMPLIFIED METHODS FOR COMBINING MECHANICAL VENTILATION AND NATURAL INFILTRATION

    SciTech Connect

    Modera, M.; Peterson, F.

    1985-01-01

    During the past ten years, the means of ventilating single-family residences has received considerable attention. In many areas, the use of natural ventilation for infiltration has either come under close scrutiny, or has already been supplanted by mechanical ventilation systems. To evaluate the energy efficiency and ventilation effectiveness of both mechanical and natural ventilation strategies, both complex and simplified infiltration models are used. This paper examines the inaccuracies associated with using simplified models to compare ventilation strategies. Two simplified techniques for combining mechanical ventilation flows to the flows caused by wind and stack effects are examined. The simplified combination techniques are compared with the results obtained with an iterative flow-balance simulation. The flow-balance simulation determines the ventilation by balancing the incoming and outgoing flows under the pressure conditions resulting from the combination of wind effect, stack effect and mechanical ventilation. These comparisons result in three major conclusions: (1) the commonly used flow superposition technique (flow combination in quadrature) provides better estimates of the total flow than does a technique that takes into account measured flow exponents, (2) although flow combination in quadrature overpredicts ventilation when combining wind-induced and stack-induced flows, this is not the case when mechanical ventilation is added to the picture, and (3) a simple correction for the errors caused by the simplified flow superposition technique is not easy to achieve due to the large variations in error that occur with changes in wind direction and individual flow ratios.

  14. Combination of metformin with chemotherapeutic drugs via different molecular mechanisms.

    PubMed

    Peng, Mei; Darko, Kwame Oteng; Tao, Ting; Huang, Yanjun; Su, Qiongli; He, Caimei; Yin, Tao; Liu, Zhaoqian; Yang, Xiaoping

    2017-03-01

    Metformin, a widely prescribed drug for treating type II diabetes, is one of the most extensively recognized metabolic modulators which has shown an important anti-cancer property. However, fairly amount of clinical trials on its single administration have not demonstrated a convincing efficiency yet. Thus, recent studies tend to combine metformin with clinical commonly used chemotherapeutic drugs to decrease their toxicity and attenuate their tumor resistance. These strategies have displayed promising clinical benefits. Interestingly, metformin experiences a diversity of molecular mechanisms when it combines different chemotherapeutic drugs. For example, AMPK/mTOR signaling pathway activation plays a major role when it combines with hormone modulating drugs. In contrast, suppression of HIF-1, p-gp and MRP1 protein expression is its main mechanism when metformin combines with anti-metabolites. Furthermore, when combining of metformin with antibiotics, inhibition of oxidative stress and inflammatory signaling pathway becomes a novel pharmaceutical mechanism for its cardio-protective effect. Induction of apoptotic mitochondria and nucleus could be the major player for the synergistic effect of its combination with cisplatin. In contrast, down-regulation of lipoprotein or cholesterol synthesis might be the undefined molecular base when metformin combines with taxane. Thus, deep exploration of molecular mechanisms of metformin with these different drugs is critical to understand its synergistic effect and help for personalized administration. In this mini-review, detailed molecular mechanisms of these combinations are discussed and summarized. This work will promote better understanding of molecular mechanisms of metformin and provide precise targets to identify specific patient groups to achieve satisfactory treatment efficacy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. The golden 35 min of stroke intervention with ADAPT: effect of thrombectomy procedural time in acute ischemic stroke on outcome.

    PubMed

    Alawieh, Ali; Pierce, Alyssa K; Vargas, Jan; Turk, Aquilla S; Turner, Raymond D; Chaudry, M Imran; Spiotta, Alejandro M

    2017-05-02

    In acute ischemic stroke (AIS), extending mechanical thrombectomy procedural times beyond 60 min has previously been associated with an increased complication rate and poorer outcomes. After improvements in thrombectomy methods, to reassess whether this relationship holds true with a more contemporary thrombectomy approach: a direct aspiration first pass technique (ADAPT). We retrospectively studied a database of patients with AIS who underwent ADAPT thrombectomy for large vessel occlusions. Patients were dichotomized into two groups: 'early recan', in which recanalization (recan) was achieved in ≤35 min, and 'late recan', in which procedures extended beyond 35 min. 197 patients (47.7% women, mean age 66.3 years) were identified. We determined that after 35 min, a poor outcome was more likely than a good (modified Rankin Scale (mRS) score 0-2) outcome. The baseline National Institutes of Health Stroke Scale (NIHSS) score was similar between 'early recan' (n=122) (14.7±6.9) and 'late recan' patients (n=75) (15.9±7.2). Among 'early recan' patients, recanalization was achieved in 17.8±8.8 min compared with 70±39.8 min in 'late recan' patients. The likelihood of achieving a good outcome was higher in the 'early recan' group (65.2%) than in the 'late recan' group (38.2%; p<0.001). Patients in the 'late recan' group had a higher likelihood of postprocedural hemorrhage, specifically parenchymal hematoma type 2, than those in the 'early recan' group. Logistic regression analysis showed that baseline NIHSS, recanalization time, and atrial fibrillation had a significant impact on 90-day outcomes. Our findings suggest that extending ADAPT thrombectomy procedure times beyond 35 min increases the likelihood of complications such as intracerebral hemorrhage while reducing the likelihood of a good outcome. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  16. Combination of biochemical and mechanical cues for tendon tissue engineering.

    PubMed

    Testa, Stefano; Costantini, Marco; Fornetti, Ersilia; Bernardini, Sergio; Trombetta, Marcella; Seliktar, Dror; Cannata, Stefano; Rainer, Alberto; Gargioli, Cesare

    2017-05-04

    Tendinopathies negatively affect the life quality of millions of people in occupational and athletic settings, as well as the general population. Tendon healing is a slow process, often with insufficient results to restore complete endurance and functionality of the tissue. Tissue engineering, using tendon progenitors, artificial matrices and bioreactors for mechanical stimulation, could be an important approach for treating rips, fraying and tissue rupture. In our work, C3H10T1/2 murine fibroblast cell line was exposed to a combination of stimuli: a biochemical stimulus provided by Transforming Growth Factor Beta (TGF-β) and Ascorbic Acid (AA); a three-dimensional environment represented by PEGylated-Fibrinogen (PEG-Fibrinogen) biomimetic matrix; and a mechanical induction exploiting a custom bioreactor applying uniaxial stretching. In vitro analyses by immunofluorescence and mechanical testing revealed that the proposed combined approach favours the organization of a three-dimensional tissue-like structure promoting a remarkable arrangement of the cells and the neo-extracellular matrix, reflecting into enhanced mechanical strength. The proposed method represents a novel approach for tendon tissue engineering, demonstrating how the combined effect of biochemical and mechanical stimuli ameliorates biological and mechanical properties of the artificial tissue compared to those obtained with single inducement. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  17. 40 CFR 280.94 - Allowable mechanisms and combinations of mechanisms.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Allowable mechanisms and combinations of mechanisms. 280.94 Section 280.94 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... OPERATORS OF UNDERGROUND STORAGE TANKS (UST) Financial Responsibility § 280.94 Allowable mechanisms...

  18. The Role of Manual Aspiration Thrombectomy in Patients Undergoing Primary Percutaneous Coronary Intervention for STEMI.

    PubMed

    Alak, Aiman; Jolly, Sanjit S

    2016-03-01

    In STEMI, primary PCI restores macrovascular coronary blood flow effectively but microvascular perfusion remains a challenge. Thrombus has the potential to embolize to the microvasculature limiting effective coronary blood flow. Thrombus burden is associated with a higher mortality and manual aspiration thrombectomy has the potential to reduce thrombus burden. The first large trial of routine aspiration thrombectomy (TAPAS, N = 1071) showed an improvement in myocardial blush and an unexpected reduction in mortality. Reinforcing the enthusiasm for this finding meta-analysis of small trials also showed a reduction in mortality, which led to routine manual thrombectomy becoming a class IIa recommendation in the American and European Guidelines for STEMI. Subsequently; however, large trials such as TOTAL (N = 10,732) and TASTE (N = 7244) and meta-analysis showed an increase in the risk of stroke with routine manual thrombectomy but no improvement in mortality, myocardial infarction, stent thrombosis, or severe heart failure. As such, manual thrombectomy should not be routinely used instead saving it as a bailout procedure as indicated.

  19. Iliocaval Stenosis and Iliac Venous Thrombosis in Retroperitoneal Fibrosis: Percutaneous Treatment by Use of Hydrodynamic Thrombectomy and Stenting

    SciTech Connect

    Vorwerk, Dierk; Guenther, Rolf W.; Wendt, Georg; Neuerburg, Joerg; Schuermann, Karl

    1996-11-15

    A case of bilateral iliac stenosis and caval stenosis due to retroperitoneal fibrosis was treated by caval stenting and iliac balloon angioplasty, but was complicated by subsequent iliac thrombosis. Venous thrombectomy was successfully achieved by hydrodynamic thrombectomy, and iliac patency was stabilized by bilateral stent insertion.

  20. View Combination: A Generalization Mechanism for Visual Recognition

    ERIC Educational Resources Information Center

    Friedman, Alinda; Waller, David; Thrash, Tyler; Greenauer, Nathan; Hodgson, Eric

    2011-01-01

    We examined whether view combination mechanisms shown to underlie object and scene recognition can integrate visual information across views that have little or no three-dimensional information at either the object or scene level. In three experiments, people learned four "views" of a two dimensional visual array derived from a three-dimensional…

  1. Percutaneous hydrodynamic thrombectomy of acute thrombosis in transjugular intrahepatic portosystemic shunt (TIPS): A feasibility study in five patients

    SciTech Connect

    Raat, Henricus; Stockx, Luc; Ranschaert, Eric; Nevens, Frederik; Wilms, Guy; Baert, Albert L.

    1997-05-15

    Purpose. To evaluate the feasibility of percutaneous hydrodynamic thrombectomy in restoring patency of acutely thrombosed stent-shunts after transjugular intrahepatic portosystemic shunt (TIPS).MethodsPercutaneous hydrodynamic thrombectomy was performed in five consecutive patients with angiographically documented complete thrombosis of the stent-shunt which developed within 2 weeks after the TIPS procedure. Thrombectomy was performed with a hydrolytic suction thrombectomy catheter, introduced via a transjugular approach.ResultsIn all patients, immediate restoration of patency of the stent-shunt was achieved after deploying additional stent(s) to cover residual adherent mural thrombus. In two patients early reocclusion occurred.ConclusionPercutaneous hydrolytic suction thrombectomy in acutely thrombosed intrahepatic portosystemic shunts is technically feasible.

  2. The golden hour of stroke intervention: effect of thrombectomy procedural time in acute ischemic stroke on outcome.

    PubMed

    Spiotta, Alejandro M; Vargas, Jan; Turner, Raymond; Chaudry, M Imran; Battenhouse, Holly; Turk, Aquilla S

    2014-09-01

    Outcome studies in acute ischemic stroke (AIS) have focused on time from symptom onset to treatment. The purpose of this study was to investigate whether time to achieve vessel recanalization from groin puncture affects outcomes. We studied all AIS cases that underwent intra-arterial therapy between May 2008 and October 2012 at a high volume center for anterior circulation occlusions. Candidacy for thrombectomy is determined by CT perfusion imaging, irrespective of time of onset. Patients were then dichotomized into two groups: 'Early recan' assigned in which recanalization was achieved in ≤60 min from groin puncture and 'Delayed recan' in which procedures extended beyond 60 min. Time to recanalize was also studied as a continuous variable. 159 patients (53.5% women, mean age 66.4±15.2 years) were identified. The mean National Institutes of Health Stroke Scale (NIHSS) score was similar between 'Early recan' patients (16.8±6.1) compared with 'Delayed recan' patients (15.4±5.8, p=0.149). Among the 'Early recan' patients, recanalization was achieved in 40.7±13.6 min compared with 101.7±32.5 min in the 'Delayed recan' patients (p<0.0001). The likelihood of achieving a good outcome (modified Rankin Scale score 0-2) was higher in the 'Early recan' group (53.6%) compared with the 'Late recan' group (30.8%; p=0.009). On logistic regression analysis, time to recanalization from groin puncture, baseline NIHSS, revascularization, diabetes, and hemorrhages were found to significantly impact on outcome at 90 days, as measured by the modified Rankin Scale. Our findings suggest that extending mechanical thrombectomy procedure times beyond 60 min increases complications and device cost rates while worsening outcomes. These findings can serve as a time frame of when it is prudent to abort a failed thrombectomy case. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  3. Combined quantum mechanical/molecular mechanics modeling for large organometallic and metallobiochemical systems

    NASA Astrophysics Data System (ADS)

    Leong, Max Kangchien

    A method of combined quantum mechanics/molecular mechanics has been developed to model larger organometallic and metallobiochemical systems where neither quantum mechanics nor molecular mechanics, applied separately, can solve the problem. An electronically transparent interface, which allows charge transfers between the quantum and classical fragments, is devised and realized by employing a special iterative procedure of double (intrafragment and interfragment) self-consistent calculations. The combined QM/MM scheme was successfully applied to model iron picket-fence porphyrin, vitamin B12, aquocobalamin, and vitamin B12 coenzyme molecules.

  4. Endovascular therapy including thrombectomy for acute ischemic stroke: A systematic review and meta-analysis with trial sequential analysis.

    PubMed

    Phan, Kevin; Zhao, Dong Fang; Phan, Steven; Huo, Ya Ruth; Mobbs, Ralph J; Rao, Prashanth J; Mortimer, Alex M

    2016-07-01

    One of the primary strategies for the management of acute ischemic stroke is intravenous (IV) thrombolysis with tissue plasminogen activator (t-PA). Over the past decade, endovascular therapies such as the use of stent retrievers to perform mechanical thrombectomy have been found to improve functional outcomes compared to t-PA alone. We aimed to reassess the functional outcomes and complications of IV thrombolysis with and without endovascular treatment for acute ischemic stroke using conventional meta-analysis and trial sequential analysis. Pooled relative risks (RR) and 95% confidence intervals (CI) were calculated for the effect of IV thrombolysis with and without endovascular therapy on functional outcome, mortality and symptomatic intracranial hemorrhage (SICH). Trial sequential analysis was done to strengthen the meta-analysis. We analyzed six randomized controlled trials involving 1943 patients. Patients who received IV thrombolysis with endovascular treatment showed significantly higher rates of excellent functional outcomes (modified Rankin Scale [mRS] 0-1) (RR, 1.75 [95% CI, 1.29-2.39]) compared to those who received IV thrombolysis alone. A similar association was seen for good functional outcomes (mRS 0-2) (RR, 1.56 [95% CI, 1.24-1.96]). Trial sequential analysis demonstrated endovascular treatment increased the RR of a good functional outcome by at least 30% compared to IV thrombolysis alone. There was no significant difference in all-cause mortality for mechanical thrombectomy compared to IV thrombolysis alone or the incidence of SICH at 3month follow-up. Endovascular treatment is more likely to result in a better functional outcome for patients compared to IV thrombolysis alone for acute ischemic stroke. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Pulmonary Hypertension Among End-Stage Renal Failure Patients Following Hemodialysis Access Thrombectomy

    SciTech Connect

    Harp, Richard J.; Stavropoulos, S. William; Wasserstein, Alan G.; Clark, Timothy W.I.

    2005-01-15

    Purpose: Percutaneous hemodialysis thrombectomy causes subclinical pulmonary emboli without short-term clinical consequence; the long-term effects on the pulmonary arterial vasculature are unknown. We compared the prevalence of pulmonary hypertension between patients who underwent one or more hemodialysis access thrombectomy procedures with controls without prior thrombectomy.Methods: A retrospective case-control study was performed. Cases (n = 88) had undergone one or more hemodialysis graft thrombectomy procedures, with subsequent echocardiography during routine investigation of comorbid cardiovascular disease. Cases were compared with controls without end-stage renal disease (ESRD) (n = 100, group 1), and controls with ESRD but no prior thrombectomy procedures (n = 117, group 2). The presence and velocity of tricuspid regurgitation on echocardiography was used to determine the prevalence and grade of pulmonary hypertension; these were compared between cases and controls using the chi-square test and logistic regression.Results: The prevalence of pulmonary hypertension among cases was 52% (46/88), consisting of mild, moderate and severe in 26% (n = 23), 10% (n = 9) and 16% (n = 14), respectively. Prevalence of pulmonary hypertension among group 1 controls was 26% (26/100), consisting of mild, moderate and severe pulmonary hypertension in 14%, 5% and 7%, respectively. Cases had 2.7 times greater odds of having pulmonary hypertension than group 1 controls (p = 0.002). The prevalence of pulmonary hypertension among group 2 controls was 42% (49/117), consisting of mild, moderate and severe pulmonary arterial hypertension in 25% (n = 49), 10% (n = 12) and 4% (n = 5), respectively. Cases were slightly more likely to have pulmonary hypertension than group 2 controls (OR = 1.5), although this failed to reach statistical significance (p = 0.14).Conclusion: Prior hemodialysis access thrombectomy does not appear to be a risk factor for pulmonary arterial hypertension

  6. Behavior of cracked cylinders under combined thermal and mechanical loading

    SciTech Connect

    Ignaccolo, S.

    1996-12-01

    Nuclear pressure vessels and pipings can be submitted in their life to severe mechanical and thermal loadings. Engineering methods easy to apply, but sufficiently accurate, are needed to assess the flaws. In the field of non-linear fracture mechanics a lot of work has been achieved for structures submitted to mechanical loadings. But for thermal loadings, and particularly for thermal gradients, only few contributions are available. The authors propose, here, to present the main results of a complete set of finite element computations, conducted in France by CEA, EDF and FRAMATOME, on cracked cylinders submitted to combined mechanical and thermal loads. The interaction between these two types of loads is analyzed in the cases of austenitic and ferritic structures. Moreover, these results are compared to the predictions obtained by simplified engineering methods (R6 procedure, J{sub SA16}, and J{sub EDF} approaches). Their domain of validity is also discussed.

  7. Inhaled nitric oxide as an adjunct to suction thrombectomy for pulmonary embolism.

    PubMed

    Faintuch, Salomão; Lang, Elvira V; Cohen, Robert I; Pinto, Duane S

    2004-11-01

    Pulmonary suction thrombectomy can be a successful interventional tool in the treatment of pulmonary thromboembolism. Removal of clot burden typically results in prompt recovery of hemodynamic stability and improved oxygenation. However, in rare cases, clot removal does not sufficiently improve the clinical situation. Herein, two patients with massive pulmonary thromboembolism are presented whose condition improved only after they received nitric oxide as an adjunct to pulmonary suction thrombectomy. The treatment with this inhalable vasodilator was based on the hypothesis that prolonged ischemia had induced microcirculatory vasospasm, persistent after removal of the central clot.

  8. Stentriever thrombectomy with distal protection device for carotid free floating thrombus: a technical case report.

    PubMed

    Giragani, Suresh; Balani, Ankit; Agrawal, Vikas

    2017-01-18

    We report the clinical details, imaging findings and management of a 45-year-old man who presented with recurrent transient ischemic attacks due to carotid free floating thrombus. Free floating thrombus of the carotid artery is a very rare condition with a high risk of distal embolic shower. The optimal treatment options are debatable and include medical management, surgical thrombectomy and endovascular thrombectomy. We describe the use of a stentriever with filter protection in the management of carotid free floating thrombus as a novel treatment option. 2017 BMJ Publishing Group Ltd.

  9. Stentriever thrombectomy with distal protection device for carotid free floating thrombus: a technical case report.

    PubMed

    Giragani, Suresh; Balani, Ankit; Agrawal, Vikas

    2017-01-25

    We report the clinical details, imaging findings and management of a 45-year-old man who presented with recurrent transient ischemic attacks due to carotid free floating thrombus. Free floating thrombus of the carotid artery is a very rare condition with a high risk of distal embolic shower. The optimal treatment options are debatable and include medical management, surgical thrombectomy and endovascular thrombectomy. We describe the use of a stentriever with filter protection in the management of carotid free floating thrombus as a novel treatment option.

  10. Comparison of Perfusion CT Software to Predict the Final Infarct Volume After Thrombectomy.

    PubMed

    Austein, Friederike; Riedel, Christian; Kerby, Tina; Meyne, Johannes; Binder, Andreas; Lindner, Thomas; Huhndorf, Monika; Wodarg, Fritz; Jansen, Olav

    2016-09-01

    Computed tomographic perfusion represents an interesting physiological imaging modality to select patients for reperfusion therapy in acute ischemic stroke. The purpose of our study was to determine the accuracy of different commercial perfusion CT software packages (Philips (A), Siemens (B), and RAPID (C)) to predict the final infarct volume (FIV) after mechanical thrombectomy. Single-institutional computed tomographic perfusion data from 147 mechanically recanalized acute ischemic stroke patients were postprocessed. Ischemic core and FIV were compared about thrombolysis in cerebral infarction (TICI) score and time interval to reperfusion. FIV was measured at follow-up imaging between days 1 and 8 after stroke. In 118 successfully recanalized patients (TICI 2b/3), a moderately to strongly positive correlation was observed between ischemic core and FIV. The highest accuracy and best correlation are shown in early and fully recanalized patients (Pearson r for A=0.42, B=0.64, and C=0.83; P<0.001). Bland-Altman plots and boxplots demonstrate smaller ranges in package C than in A and B. Significant differences were found between the packages about over- and underestimation of the ischemic core. Package A, compared with B and C, estimated more than twice as many patients with a malignant stroke profile (P<0.001). Package C best predicted hypoperfusion volume in nonsuccessfully recanalized patients. Our study demonstrates best accuracy and approximation between the results of a fully automated software (RAPID) and FIV, especially in early and fully recanalized patients. Furthermore, this software package overestimated the FIV to a significantly lower degree and estimated a malignant mismatch profile less often than other software. © 2016 American Heart Association, Inc.

  11. Increasing Efficacy of Thrombectomy by Using Digital Subtraction Angiography to Confirm Stent Retriever Clot Integration

    PubMed Central

    Simon, Scott; Cooke, Jonathon

    2016-01-01

    Physicians performing thrombectomy for acute stroke have had increasing success as thrombectomy-specific devices have continued to evolve. As the devices evolve, so too must the techniques. The current generation of stent retriever thrombectomy devices requires five minutes of dwell time, regardless of the particularities of the case. We have noticed the presence of flow through the stent immediately prior to removal portends a lower chance of successful thrombus retrieval than when no flow is seen, regardless of dwell time. We hypothesize that interventionalists can use the presence or absence of flow to predict adequacy of seating time and decrease the number of deployments per case. This could significantly decrease time to recanalization by avoiding time-consuming, unsuccessful pulls. This is a technical report of a few cases of stent retriever thrombectomy. We propose using post-deployment digital subtraction angiography to confirm thrombus-device integration and increase the chance of thrombus removal. PMID:27182473

  12. Endovascular treatment of iliofemoral deep vein thrombosis in pregnancy using US-guided percutaneous aspiration thrombectomy

    PubMed Central

    Gedikoglu, Murat; Oguzkurt, Levent

    2017-01-01

    PURPOSE We aimed to describe ultrasonography (US)-guided percutaneous aspiration thrombectomy in pregnant women with iliofemoral deep vein thrombosis. METHODS This study included nine pregnant women with acute and subacute iliofemoral deep vein thrombosis, who were severe symptomatic cases with massive swelling and pain of the leg. Patients were excluded from the study if they had only femoropopliteal deep vein thrombosis or mild symptoms of deep vein thrombosis. US-guided percutaneous aspiration thrombectomy was applied to achieve thrombus removal and uninterrupted venous flow. The treatment was considered successful if there was adequate venous patency and symptomatic relief. RESULTS Complete or significant thrombus removal and uninterrupted venous flow from the puncture site up to the iliac veins were achieved in all patients at first intervention. Complete relief of leg pain was achieved immediately in seven patients (77.8%). Two patients (22.2%) had a recurrence of thrombosis in the first week postintervention. One of them underwent a second intervention, where percutaneous aspiration thrombectomy was performed again with successful removal of thrombus and establishment of in line flow. Two patients were lost to follow-up after birth. None of the remaining seven patients had rethrombosis throughout the postpartum period. Symptomatic relief was detected clinically in these patients. CONCLUSION Endovascular treatment with US-guided percutaneous aspiration thrombectomy can be considered as a safe and effective way to remove thrombus from the deep veins in pregnant women with acute and subacute iliofemoral deep vein thrombosis. PMID:27801353

  13. Cost-effectiveness of endovascular thrombectomy in patients with acute ischemic stroke.

    PubMed

    Aronsson, Mattias; Persson, Josefine; Blomstrand, Christian; Wester, Per; Levin, Lars-Åke

    2016-03-15

    To evaluate the cost-effectiveness of adding endovascular thrombectomy to standard care in patients with acute ischemic stroke. The cost-effectiveness analysis of endovascular thrombectomy in patients with acute ischemic stroke was based on a decision-analytic Markov model. Primary outcomes from ESCAPE, Extending the Time for Thrombolysis in Emergency Neurological Deficits-Intra-Arterial (EXTEND-IA), Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands (MR CLEAN), Endovascular Revascularization With Solitaire Device Versus Best Medical Therapy in Anterior Circulation Stroke Within 8 Hours (REVASCAT), and Solitaire with the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke (SWIFT PRIME) along with data from published studies and registries were used in this analysis. We used a health care payer perspective and a lifelong time horizon to estimate costs and effects. The model showed that adding thrombectomy with stent retrievers to guideline-based care (including IV thrombolysis) resulted in a gain of 0.40 life-years and 0.99 quality-adjusted life-years along with a cost savings of approximately $221 per patient. The sensitivity analysis showed that the results were not sensitive to changes in uncertain parameters or assumptions. Adding endovascular treatment to standard care resulted in substantial clinical benefits at low costs. The results were consistent throughout irrespective of whether data from ESCAPE, EXTEND-IA, MR CLEAN, REVASCAT, or SWIFT PRIME were used in this model. © 2016 American Academy of Neurology.

  14. Coronary artery embolism from infectious endocarditis treated with catheter thrombectomy using a GuideLiner catheter.

    PubMed

    Oestreich, Brett A; Sommer, Per; Armstrong, Ehrin J

    2016-04-01

    A 27-year-old male with history of IV drug use and recurrent endocarditis necessitating bioprosthetic mitral and tricuspid valve replacements presented with 2 weeks of fevers and chest pain. ECG revealed inferior ST-elevation myocardial infarction and he was taken urgently to the cardiac catheterization laboratory. Coronary angiography revealed thrombotic occlusion of the distal right coronary artery (RCA) with no angiographic evidence of atherosclerotic disease. Aspiration thrombectomy was performed followed by rheolytic thrombectomy. Despite multiple attempts at thrombectomy, significant residual organized thrombus persisted in the distal RCA. Therefore, further thrombectomy was performed by placing a GuideLiner catheter (Vascular Solutions, Minneapolis, MN) deep within the right coronary artery near the bifurcation into the posterior descending and posterior left ventricular arteries. After repeat aspiration, there was significant improvement with thrombolysis in myocardial infarction 3 flow. Intravascular ultrasound of the RCA revealed a normal-appearing vessel without evidence of atherosclerotic disease and mild residual thrombus. The decision was made to not pursue stent placement, given the concern for a likely embolic source. Following the procedure, the patient's chest pain resolved and his ST-segments normalized. © 2015 Wiley Periodicals, Inc.

  15. Bifurcated aortic endograft limb occlusion managed with a novel method of isolated pharmacomechanical thrombectomy.

    PubMed

    Pappy, Reji; Hanna, Elias B; Hennebry, Thomas A

    2010-11-15

    Limb occlusion of an aortic endograft is uncommon, however, it can result in permanent sequelae if management is delayed. We report the first case utilizing the Trellis device to achieve localized and prompt isolated pharmacomechanical thrombectomy (PMT) for the treatment of acute limb thrombosis of a bifurcated aortic endograft. Copyright © 2010 Wiley-Liss, Inc.

  16. [Thrombosis of the right atrium after umbilical venous catheterization. Favourable outcome after early thrombectomy].

    PubMed

    Paupe, A; Lenclen, R; Blanc, P; Chassevent, J; Hoenn, E; Molho, M; Zannier, D; Olivier-Martin, M

    1992-02-01

    A case of right atrial thrombosis after venous umbilical catheterization in a 21 day-old premature newborn is reported. The initiating factors of such an accident and its clinical signs are evocated. The authors emphasize the value of a systematic ultrasonographic supervision of newborns with central catheters for a long period of time and the value of surgical thrombectomy.

  17. Rescue strategy for acute carotid stent thrombosis during carotid stenting with distal filter protection using forced arterial suction thrombectomy with a reperfusion catheter of the Penumbra System: a technical note.

    PubMed

    Kim, Yong-Won; Kang, Dong-Hun; Hwang, Jeong-Hyun; Park, Jaechan; Hwang, Yang-Ha; Kim, Yong-Sun

    2013-08-01

    Among the procedural complications related to carotid artery stenting (CAS), internal carotid artery (ICA) flow arrest is one of the most drastic complications, as it can cause major ischemic stroke. Acute carotid stent thrombosis (ACST) is a rare etiology of ICA flow arrest during carotid artery stenting with distal filter protection, but the most devastating. Moreover, no definitive management strategy has been established so far for treating ACST. We introduce a rescue management strategy for differential diagnosis of ICA flow arrest and for recanalization of ACST with a simple endovascular mechanical thrombectomy technique. In three cases of ICA flow arrest caused by ACST, selective angiography with a 1.7 F microcatheter provided confirmative diagnosis. Recanalization was then achieved with a Penumbra System (PS) reperfusion catheter using the forced arterial suction thrombectomy (FAST) technique. Successful recanalization with a Thrombolysis In Cerebral Infarction score of 3 was achieved for all three patients. Recanalization was confirmed with follow-up angiography at least 24 h after the procedure. No complications associated with this technique occurred. Based on our preliminary experiences, selective microangiography can be helpful for rapid diagnosis of ACST, and the present mechanical thrombectomy technique, using a modification of the PS, can play a role in adjuvant management or as a last resort for the treatment of ACST during CAS.

  18. Number needed to treat for stroke thrombectomy based on a systematic review and meta-analysis.

    PubMed

    Church, Ephraim W; Gundersen, Alexandra; Glantz, Michael J; Simon, Scott D

    2017-05-01

    The positive results of recent clinical trials examining endovascular treatment of acute stroke were the culmination of nearly two decades of studies of endovascular stroke treatment. We systematically reviewed this body of work, evaluated the strength of evidence, and performed a meta-analysis to define the clinical impact of these investigations. Terms were entered into search engines in a systematic fashion. Articles were reviewed independently by study authors, graded for level of evidence, and combined in a meta-analysis. The overall body of evidence was evaluated using GRADE criteria. Our search yielded 948 articles. Twenty-five met predefined inclusion criteria. We identified 12 grade I, 1 grade II, 5 grade III, and 7 grade IV studies (κ=0.86). Meta-analysis for independence at 90days showed a benefit of endovascular treatment (grade I studies OR 1.58 [1.20-2.07]). When limiting the analysis to studies using stent retriever, the OR increased to 2.44 (1.77-3.36). The number needed to treat (NNT) was 8. Endovascular treatment was not associated with increased symptomatic intracranial hemorrhage, and forgoing endovascular treatment was associated with death at 90 days. The quality of evidence according to GRADE criteria was "moderate." In summary, we found impressive evidence for a benefit of endovascular treatment of acute stroke, particularly when using stent retriever devices. Our meta-analysis is unique in that it includes all studies related to this topic and defines the clinical impact of the data, providing NNT. We show that thrombectomy is among the most effective stroke treatments currently available. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Thrombectomy reduces the systemic complications in device-related right atrial septic thrombosis

    PubMed Central

    Sontineni, Siva Prasad; White, Michael; Singh, Sindhu; Arouni, Amy; Cloutier, David; Nair, Chandra K; Mohiuddin, Syed M

    2009-01-01

    BACKGROUND: Septic thrombosis of the right atrium is an unusual complication associated with the use of indwelling devices. The optimal management of this condition is unclear. Our experience with a patient with hemodialysis catheter-related septic thrombosis of the right atrium illustrates the difficulties associated with this condition. OBJECTIVES: To determine the effects of surgical thrombectomy compared with nonsurgical treatment with antibiotics (with or without anticoagulation) on mortality rates and complications in patients with device-related septic thrombosis of the right atrium. METHODS: A retrospective analysis of all reported cases of device-related right heart septic thrombosis in which therapy and outcome were reported was conducted using a PubMed search in the English-language literature (1985 to 2006). RESULTS: Forty cases of device-related right atrial septic thromboses were reported in the literature during the chosen time period. The treatments administered were none (12.5%), antibiotics (12.5%), antibiotics and anticoagulation (20%), and thrombectomy (55%). The mean clot size was significantly larger in patients who underwent thrombectomy. All untreated patients died. Excluding the untreated patients from the analysis, systemic complications were significantly lower in the thrombectomy group than in the groups receiving nonsurgical therapies. Using multivariate modelling with survival as the primary outcome, age, sex, clot size, clot location, microbial organism or type of treatment were not predictive of the outcome. CONCLUSION: Device-related right atrial septic thrombosis is associated with significant mortality and is uniformly fatal if untreated. Surgical thrombectomy is associated with less frequent systemic complications. A well-designed prospective, randomized trial is needed to determine the optimal treatment of this condition. PMID:19214299

  20. Interfacility Transfer Directly to the Neuroangiography Suite in Acute Ischemic Stroke Patients Undergoing Thrombectomy.

    PubMed

    Jadhav, Ashutosh P; Kenmuir, Cynthia L; Aghaebrahim, Amin; Limaye, Kaustubh; Wechsler, Lawrence R; Hammer, Maxim D; Starr, Matthew T; Molyneaux, Bradley J; Rocha, Marcelo; Guyette, Francis X; Martin-Gill, Christian; Ducruet, Andrew F; Gross, Bradley A; Jankowitz, Brian T; Jovin, Tudor G

    2017-07-01

    In patients identified at referring facilities with acute ischemic stroke caused by a large vessel occlusion, bypassing the emergency department (ED) with direct transport to the neuroangiography suite may safely shorten reperfusion times. We conducted a single-center retrospective review of consecutive patients transferred to our facility for consideration of endovascular therapy. Patients were identified as admitted directly to the neuroangiography suite (DAN), transferred to the ED before intra-arterial therapy (ED-IA), and transferred to the ED but did not receive IA therapy (ED-IV). A retrospective review of a prospectively maintained database of transfer patients between January 2013 and October 2016 with large vessel occlusions identified 108 ED-IV patients and 261 patients who underwent mechanical thrombectomy (DAN=111 patients and ED-IA=150 patients). There were no differences in baseline characteristics among the 3 groups. The median computed tomography ASPECTS (Alberta Stroke Program Early CT Score) was lower in the ED-IV group versus the ED-IA and DAN groups (8 versus 9; P=0.001). In the DAN versus ED-IA cohort, there were comparable rates of TICI2b/3 recanalization and access to recanalization time. There was significantly faster hospital arrival to groin access time in the DAN cohort (81 minutes versus 22 minutes; P=0.001). Functional independence at 90 days was comparable in the DAN versus ED-IA cohorts but worse in the ED-IV group (43% versus 44% versus 22%; P=0.001). DAN is safe, feasible, and associated with faster times of hospital arrival to recanalization. The clinical benefit of this approach should be assessed in a prospective randomized trial. © 2017 American Heart Association, Inc.

  1. 40 CFR 280.94 - Allowable mechanisms and combinations of mechanisms.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... requirements of the financial test under this rule, the financial statements of the owner or operator are not consolidated with the financial statements of the guarantor. ... 40 Protection of Environment 28 2012-07-01 2012-07-01 false Allowable mechanisms and combinations...

  2. Gelled Complex Fluids: Combining Unique Structures with Mechanical Stability.

    PubMed

    Stubenrauch, Cosima; Gießelmann, Frank

    2016-03-01

    Gelled complex fluids are soft materials in which the microstructure of the complex fluid is combined with the mechanical stability of a gel. To obtain a gelled complex fluid one either adds a gelator to a complex fluid or replaces the solvent in a gel by a complex fluid. The most prominent example of a "natural" gelled complex fluid is the cell. There are various strategies by which one can form a gelled complex fluid; one such strategy is orthogonal self-assembly, that is, the independent but simultaneous formation of two coexisting self-assembled structures within one system. The aim of this Review is to describe the structure and potential applications of various man-made gelled complex fluids and to clarify whether or not the respective system is formed by orthogonal self-assembly.

  3. Physiological Mechanisms in Combined Electric-Acoustic Stimulation.

    PubMed

    Sato, Mika; Baumhoff, Peter; Tillein, Jochen; Kral, Andrej

    2017-09-01

    Electrical stimulation is normally performed on ears that have no hearing function, i.e., lack functional hair cells. The properties of electrically-evoked responses in these cochleae were investigated in several previous studies. Recent clinical developments have introduced cochlear implantation (CI) in residually-hearing ears to improve speech understanding in noise. The present study documents the known physiological differences between electrical stimulation of hair cells and of spiral ganglion cells, respectively, and reviews the mechanisms of combined electric and acoustic stimulation in the hearing ears. Literature review from 1971 to 2016. Compared with pure electrical stimulation the combined electroacoustic stimulation provides additional low-frequency information and expands the dynamic range of the input. Physiological studies document a weaker synchronization of the evoked activity in electrically stimulated hearing ears compared with deaf ears that reduces the hypersynchronization of electrically-evoked activity. The findings suggest the possibility of balancing the information provided by acoustic and electric input using stimulus intensity. Absence of distorting acoustic-electric interactions allows exploiting these clinical benefits of electroacoustic stimulation.

  4. Surgical thrombectomy and transluminal balloon angioplasty for failed above-knee femoropopliteal polytetrafluoroethylene bypass grafts.

    PubMed

    Costanza, Michael J; Neschis, David G; Queral, Luis A; Flinn, William R

    2004-03-01

    Endovascular therapy offers an alternative to redo bypass or surgical graft revision for failed above-knee femoropopliteal PTFE bypass grafts. We evaluated the outcome of surgical thrombectomy and balloon angioplasty for the treatment of thrombosed bypass grafts. Thirty selected patients with thrombosed above-knee femoropopliteal PTFE bypass grafts were treated. Under local anesthesia, a surgical thrombectomy followed by bypass graft angiography and balloon angioplasty of perianastomotic stenoses was performed. Stents were used selectively for suboptimal angioplasty results. Patients underwent duplex scanning of the bypass graft postoperatively and at 6-month intervals. Life-table analysis and log-rank (Mantel-Cox) comparisons were performed. Patients were categorized into two groups on the basis of time elapsed from initial bypass graft construction to graft failure. Group 1 included 21 patients with a mean time to graft failure of 10 months (range, 0-20). Surgical thrombectomy was successful in 20 grafts (95%) and 17 patients had a stent placed after angioplasty. Rethrombosis occurred within 30 days in seven grafts (33%) in group 1 and major amputations were performed in six patients (28%). Group 2 included nine patients with a mean time to initial bypass graft failure of 48 months (range, 29-96). All patients in group 2 had a successful surgical thrombectomy and all received a stent. None of the grafts treated in group 2 reoccluded within 30 days of intervention and one patient (11%) went on to require a major amputation. By life-table analysis, the 6- and 12-month patency for group 1 was 15.3% and 5.1%, compared to 58.3% and 38.9% for group 2 (p = 0.027). Surgical thrombectomy along with balloon angioplasty has an unacceptably high rate of failure and limb loss in patients treated for early (<2 years) femoropopliteal PTFE bypass graft thrombosis. Surgical graft revision or redo bypass is recommended to achieve successful revascularization in these patients

  5. Apparent-Strain Correction for Combined Thermal and Mechanical Testing

    NASA Technical Reports Server (NTRS)

    Johnson, Theodore F.; O'Neil, Teresa L.

    2007-01-01

    Combined thermal and mechanical testing requires that the total strain be corrected for the coefficient of thermal expansion mismatch between the strain gage and the specimen or apparent strain when the temperature varies while a mechanical load is being applied. Collecting data for an apparent strain test becomes problematic as the specimen size increases. If the test specimen cannot be placed in a variable temperature test chamber to generate apparent strain data with no mechanical loads, coupons can be used to generate the required data. The coupons, however, must have the same strain gage type, coefficient of thermal expansion, and constraints as the specimen to be useful. Obtaining apparent-strain data at temperatures lower than -320 F is challenging due to the difficulty to maintain steady-state and uniform temperatures on a given specimen. Equations to correct for apparent strain in a real-time fashion and data from apparent-strain tests for composite and metallic specimens over a temperature range from -450 F to +250 F are presented in this paper. Three approaches to extrapolate apparent-strain data from -320 F to -430 F are presented and compared to the measured apparent-strain data. The first two approaches use a subset of the apparent-strain curves between -320 F and 100 F to extrapolate to -430 F, while the third approach extrapolates the apparent-strain curve over the temperature range of -320 F to +250 F to -430 F. The first two approaches are superior to the third approach but the use of either of the first two approaches is contingent upon the degree of non-linearity of the apparent-strain curve.

  6. Atomistic insight into the catalytic mechanism of glycosyltransferases by combined quantum mechanics/molecular mechanics (QM/MM) methods.

    PubMed

    Tvaroška, Igor

    2015-02-11

    Glycosyltransferases catalyze the formation of glycosidic bonds by assisting the transfer of a sugar residue from donors to specific acceptor molecules. Although structural and kinetic data have provided insight into mechanistic strategies employed by these enzymes, molecular modeling studies are essential for the understanding of glycosyltransferase catalyzed reactions at the atomistic level. For such modeling, combined quantum mechanics/molecular mechanics (QM/MM) methods have emerged as crucial. These methods allow the modeling of enzymatic reactions by using quantum mechanical methods for the calculation of the electronic structure of the active site models and treating the remaining enzyme environment by faster molecular mechanics methods. Herein, the application of QM/MM methods to glycosyltransferase catalyzed reactions is reviewed, and the insight from modeling of glycosyl transfer into the mechanisms and transition states structures of both inverting and retaining glycosyltransferases are discussed.

  7. Inactivation mechanism of glycerol dehydration by diol dehydratase from combined quantum mechanical/molecular mechanical calculations.

    PubMed

    Doitomi, Kazuki; Kamachi, Takashi; Toraya, Tetsuo; Yoshizawa, Kazunari

    2012-11-13

    Inactivation of diol dehydratase during the glycerol dehydration reaction is studied on the basis of quantum mechanical/molecular mechanical calculations. Glycerol is not a chiral compound but contains a prochiral carbon atom. Once it is bound to the active site, the enzyme adopts two binding conformations. One is predominantly responsible for the product-forming reaction (G(R) conformation), and the other primarily contributes to inactivation (G(S) conformation). Reactant radical is converted into a product and byproduct in the product-forming reaction and inactivation, respectively. The OH group migrates from C2 to C1 in the product-forming reaction, whereas the transfer of a hydrogen from the 3-OH group of glycerol to C1 takes place during the inactivation. The activation barrier of the hydrogen transfer does not depend on the substrate-binding conformation. On the other hand, the activation barrier of OH group migration is sensitive to conformation and is 4.5 kcal/mol lower in the G(R) conformation than in the G(S) conformation. In the OH group migration, Glu170 plays a critical role in stabilizing the reactant radical in the G(S) conformation. Moreover, the hydrogen bonding interaction between Ser301 and the 3-OH group of glycerol lowers the activation barrier in G(R)-TS2. As a result, the difference in energy between the hydrogen transfer and the OH group migration is reduced in the G(S) conformation, which shows that the inactivation is favored in the G(S) conformation.

  8. Antiphospholipid syndrome and acute myocardial infarction: treatment with thrombectomy and abciximab.

    PubMed

    Martí, Vicens; Seixo, Filipe; Santaló, Miguel; Serra, Antonio

    2014-01-01

    Antiphospholipid syndrome (APS) is an autoimmune coagulation disorder that manifests clinically as venous and arterial thrombosis, and may affect any tissue or organ. Coronary artery involvement, however, is very rare. Case reports in the literature describing patients with coronary acute syndrome and APS treated with coronary angioplasty show conflicting results. We report an adult male patient with APS who presented with an acute myocardial infarction. Given the high risk of thrombosis in these patients, he was treated percutaneously with thrombectomy and abciximab. We review the few cases of coronary angioplasty in patients with APS reported to date. To our knowledge, this is the first case in which acute myocardial infarction due to thrombotic coronary occlusion was treated with thrombectomy and abciximab without stenting the artery. Copyright © 2013 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

  9. Endovascular Aneurysm Repair with Balloon Thrombectomy for Acute Thrombosis of Abdominal Aortic Aneurysm.

    PubMed

    Uotani, Kensuke; Hamanaka, Akihiro; Matsushiro, Keigo; Idaka, Erika; Ito, Kiyo; Yamasaki, Yuko; Kushima, Takeyuki; Sugimoto, Takaki; Sugimoto, Koji

    2017-08-17

    Acute occlusion of abdominal aortic aneurysm (AAA) is a rare complication and is usually treated with surgical reconstruction. We present a case of acute AAA occlusion that was successfully treated by endovascular aneurysm repair (EVAR) with Fogarty balloon thrombectomy. A 77-year-old man with a history of acute myocardial ischemia presented with limb weakness and coldness. Contrast-enhanced computed tomography showed a 42-mm-diameter infrarenal AAA that was completely thrombosed in the distal portion. The proximal neck of the aneurysm was patent, and its shape was suitable for EVAR. Therefore, we performed balloon thrombectomy of the aortoiliac thrombus that was followed by EVAR. EVAR can be a less invasive alternative than traditional treatment for acute occlusion of AAA.

  10. Combined quantum mechanics/molecular mechanics (QM/MM) methods in computational enzymology.

    PubMed

    van der Kamp, Marc W; Mulholland, Adrian J

    2013-04-23

    Computational enzymology is a rapidly maturing field that is increasingly integral to understanding mechanisms of enzyme-catalyzed reactions and their practical applications. Combined quantum mechanics/molecular mechanics (QM/MM) methods are important in this field. By treating the reacting species with a quantum mechanical method (i.e., a method that calculates the electronic structure of the active site) and including the enzyme environment with simpler molecular mechanical methods, enzyme reactions can be modeled. Here, we review QM/MM methods and their application to enzyme-catalyzed reactions to investigate fundamental and practical problems in enzymology. A range of QM/MM methods is available, from cheaper and more approximate methods, which can be used for molecular dynamics simulations, to highly accurate electronic structure methods. We discuss how modeling of reactions using such methods can provide detailed insight into enzyme mechanisms and illustrate this by reviewing some recent applications. We outline some practical considerations for such simulations. Further, we highlight applications that show how QM/MM methods can contribute to the practical development and application of enzymology, e.g., in the interpretation and prediction of the effects of mutagenesis and in drug and catalyst design.

  11. Supradiaphragmatic Inferior Vena Caval Thrombectomy Without Cardiopulmonary Bypass: A Case Series at a Single Center

    PubMed Central

    Soleimani, Mohammad; Mohammadi, Reza; Masoumi, Navid; Safarinejad, Mohammad Reza

    2016-01-01

    Introduction Inferior vena cava tumor thrombectomy in renal cell carcinoma patients is a challenging procedure, frequently requiring the vascular bypass technique for high-level thrombi with additional complications. Adopting a technique such as intrapericardial control in selected cases will circumvent these problems. Here, we present the results of our intrapericardial control technique during supradiaphragmatic inferior vena caval tumor thrombectomy. Case Presentation The records of six patients with supradiaphragmatic tumor thrombi, who underwent radical nephrectomy and thrombectomy at our center with intrapericardial control between the years 2008 and 2015, were retrospectively reviewed. The patients’ characteristics, intra- and postoperative data, histology, and follow-up records were gathered and compared. There were no immediate or 30-day postoperative deaths. The mean age of the patients was 61.3 years (range 46 - 75). The total mean duration of surgery was 315 minutes and the mean amount of transfused red blood cells was 4.33 units during surgery and 0.8 units in the postoperative period. The average hospitalization duration was 8 days (range 5 - 17). Tumor stage was T3 in four patients and T4 in two, due to ipsilateral adrenal involvement. The mean duration of follow-up was 33.5 months. Only one of the patients developed recurrences, first in the tumor bed and then at the site of the skin incision; these were excised with no apparent complications. Conclusions Radical nephrectomy and tumor thrombectomy by intrapericardial control without cardiopulmonary bypass and hypothermic circulatory arrest is a safe and effective procedure that can avoid serious intra- and postoperative complications while providing acceptable cancer-control and mortality results. PMID:27878115

  12. Rheolytic Thrombectomy of an Acutely Thrombosed Transjugular Intrahepatic Portosystemic Stent Shunt

    SciTech Connect

    Mueller-Huelsbeck, Stefan; Link, Johann; Hoepfner, Michael; Loeser, Christian; Heller, Martin

    1996-04-15

    As an alternative to chemical thrombolysis, an acutely occluded transjugular intrahepatic portosystemic stent shunt in a 72-year-old woman was successfully recanalized using a 5 Fr rheolytic catheter system. No adjunctive thrombectomy treatment was necessary. The underlying stenotic leason was treated with percutaneous transluminal angioplasty and a Palmaz stent. Immediately after the intervention optimal shunt flow was achieved. Ascites vanished within a few days and no further bleeding complications appeared.

  13. Thrombolysis and thrombectomy in patients treated with dabigatran with acute ischemic stroke: Expert opinion.

    PubMed

    Diener, H C; Bernstein, R; Butcher, K; Campbell, B; Cloud, G; Davalos, A; Davis, S; Ferro, J M; Grond, M; Krieger, D; Ntaios, G; Slowik, A; Touzé, E

    2017-01-01

    Systemic thrombolysis with rt-PA is contraindicated in patients with acute ischemic stroke anticoagulated with dabigatran. This expert opinion provides guidance on the use of the specific reversal agent idarucizumab followed by rt-PA and/or thrombectomy in patients with ischemic stroke pre-treated with dabigatran. The use of idarucizumab followed by rt-PA is covered by the label of both drugs.

  14. Primary combined androgen blockade in localized disease and its mechanism.

    PubMed

    Namiki, Mikio; Kitagawa, Yasuhide; Mizokami, Atsushi; Koh, Eitetsu

    2008-04-01

    In spite of clinical practice guidelines such as NCI-PDQ - in which primary androgen deprivation therapy (PADT) is not recommended as the primary treatment for localized prostate cancer - many patients have been treated with PADT. One of the reasons is that urologists themselves permit patients' desire because they know the effectiveness of PADT for some patients in their experiences. In this review we demonstrate basic mechanisms and the clinical efficacy of primary combined androgen blockade (PCAB) for localized or locally advanced prostate cancer. Then we discuss which patients are candidates for PCAB, and show that more than 30% of low- or intermediate-risk localized prostate cancers could be controlled in the long term with only PCAB. Short-term or intermittent PADT could not be recommended because of the possibilities of changing the character of the cancer cells by incomplete androgen ablation. We propose algorithms for the treatment of localized prostate cancer not only in low- and intermediate-risk groups but also in the high-risk group.

  15. [Sorption and mechanism of surfactants on bentonite in combined pollution].

    PubMed

    Sun, Xiao-Hui; Lu, Ying-Ying; Chen, Shu-Guang; Li, Ling-Jian; Shen, Xue-You

    2007-04-01

    Sorption of cationic surfactant cetyl pyridinium chloride (CPC), anionic surfactant sodium dodecylbenzene sulfonate (SDBS) and nonionic surfactant Triton X-100 (TX-100) on bentonite was studied. The influences of cation-exchange capacity (CEC), temperature and salinity on the sorption of CPC were also discussed. The results indicate that the sorption of CPC on Na-bentonite is greater than that of TX-100 and SDBS, and SDBS hardly shows any sorption. CPC is adsorbed to Na-bentonite through a combination of hydrophobic bonding and cation-exchange. While TX-100 is adsorbed to Na-bentonite via the formation of an adsorption layer of twain surfactant molecule and hydrogenolysis of silicon-oxygen surface of bentonite and TX-100. The amount of SDBS adsorbed on Ca-bentonite increases with increasing surfactant concentration, reaching a maximum at 1.5 critical micelle concentration (CMC), and then decreases with increasing surfactant loading. The mechanism of the retention appears to be formation of a sparingly soluble Ca-SDBS species, and dissolution in the micelle. The amount of CPC adsorbed on bentonite decreases with increasing temperature, and increases with increasing CEC. NaCl can enhance the sorption of CPC on bentonite.

  16. Feasibility of Crosslinked Acrylic Shape Memory Polymer for a Thrombectomy Device.

    PubMed

    Muschenborn, Andrea D; Hearon, Keith; Volk, Brent L; Conway, Jordan W; Maitland, Duncan J

    2014-02-25

    To evaluate the feasibility of utilizing a system of SMP acrylates for a thrombectomy device by determining an optimal crosslink density that provides both adequate recovery stress for blood clot removal and sufficient strain capacity to enable catheter delivery. Four thermoset acrylic copolymers containing benzylmethacrylate (BzMA) and bisphenol A ethoxylate diacrylate (Mn~512, BPA) were designed with differing thermomechanical properties. Finite element analysis (FEA) was performed to ensure that the materials were able to undergo the strains imposed by crimping, and fabricated devices were subjected to force-monitored crimping, constrained recovery, and bench-top thrombectomy. Devices with 25 and 35 mole% BPA exhibited the highest recovery stress and the highest brittle response as they broke upon constrained recovery. On the contrary, the 15 mole % BPA devices endured all testing and their recovery stress (5 kPa) enabled successful bench-top thrombectomy in 2/3 times, compared to 0/3 for the devices with the lowest BPA content. While the 15 mole% BPA devices provided the best trade-off between device integrity and performance, other SMP systems that offer recovery stresses above 5 kPa without increasing brittleness to the point of causing device failure would be more suitable for this application.

  17. Treatment of acute embolic occlusions of the subclavian and axillary arteries using a rotational thrombectomy device.

    PubMed

    Zeller, T; Frank, U; Bürgelin, K; Sinn, L; Horn, B; Schwarzwälder, U; Roskamm, H; Neumann, F J

    2003-05-01

    Acute embolic or local thrombotic ischaemia of the upper limbs can be treated by embolectomy or by endovascular techniques. We report here on the endovascular thrombectomy of acute embolic occlusions of subclavian and axillary arteries in two patients using a rotational thrombectomy device and give an overview about the actual literature. Two female patients, each with a history of multivessel coronary disease and intermittent atrial fibrillation, complained of sudden onset of pain at rest and paleness of the left and right arm, respectively. Duplex ultrasound showed a localized embolic occlusion of the left subclavian artery and the bifurcation of the brachial artery in the first patient and a localized embolic occlusion of the distal right subclavian and axillary artery in the second patient. In the first patient, the left subclavian artery was reopened using a 8F-Rotarex device via the femoral access, while the bifurcation of the brachial artery was reopened by local thrombolysis using 25 mg rt-PA because of the insufficient length of the thrombectomy device of 80 cm. In the second patient, the right subclavian and axillary arteries were reopened using a 6F-Rotarex device. Follow-up examinations before discharge and after 6 months showed normalized perfusion of the arms of both patients.

  18. Treatment options and outcomes for caval thrombectomy and resection for renal cell carcinoma.

    PubMed

    Haidar, Georges M; Hicks, Taylor D; El-Sayed, Hosam F; Davies, Mark G

    2017-05-01

    Advanced renal cell carcinoma (RCC) has a significant predisposition to vascular invasion. Tumor vascular invasion and thrombus are found in the renal vein and the inferior vena cava (IVC) in up to 10% to 25% of patients. This study reviewed the current status of radical nephrectomy with IVC thrombectomy for advanced RCC. A two-level search strategy of the literature (MEDLINE, PubMed, The Cochrane Library, and Google Scholar) for relevant articles listed between January 2000 and December 2015 was performed. The review was confined to patients with primary RCC associated with vascular invasion. Untreated RCC with intravascular thrombus has a median survival of 5 months. Surgical exposure and intervention are tailored to the level of tumor thrombus. The 30-day mortality for radical nephrectomy with IVC thrombectomy is low (1.5%-10%), and the complication rates have been reported to be 18%, 20%, 26%, and 47% for IVC tumor thrombus level I, II, III, and IV disease, respectively. Disease-specific survival ranges from 40% to 60% at 5 years after nephrectomy and removal of the intravascular tumor. Radical nephrectomy with IVC thrombectomy is an effective cancer control operation that can be safely performed with acceptable mortality and morbidity. Preoperative imaging coupled with perioperative surgical management of the IVC is critical to procedural success and patient outcomes. Copyright © 2017 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

  19. Feasibility of Crosslinked Acrylic Shape Memory Polymer for a Thrombectomy Device

    PubMed Central

    Muschenborn, Andrea D.; Hearon, Keith; Volk, Brent L.; Conway, Jordan W.; Maitland, Duncan J.

    2014-01-01

    Purpose To evaluate the feasibility of utilizing a system of SMP acrylates for a thrombectomy device by determining an optimal crosslink density that provides both adequate recovery stress for blood clot removal and sufficient strain capacity to enable catheter delivery. Methods Four thermoset acrylic copolymers containing benzylmethacrylate (BzMA) and bisphenol A ethoxylate diacrylate (Mn~512, BPA) were designed with differing thermomechanical properties. Finite element analysis (FEA) was performed to ensure that the materials were able to undergo the strains imposed by crimping, and fabricated devices were subjected to force-monitored crimping, constrained recovery, and bench-top thrombectomy. Results Devices with 25 and 35 mole% BPA exhibited the highest recovery stress and the highest brittle response as they broke upon constrained recovery. On the contrary, the 15 mole % BPA devices endured all testing and their recovery stress (5 kPa) enabled successful bench-top thrombectomy in 2/3 times, compared to 0/3 for the devices with the lowest BPA content. Conclusion While the 15 mole% BPA devices provided the best trade-off between device integrity and performance, other SMP systems that offer recovery stresses above 5 kPa without increasing brittleness to the point of causing device failure would be more suitable for this application. PMID:25414549

  20. Performance of a thrombectomy device for aspiration of thrombus with various sizes based on a computational fluid dynamic modeling.

    PubMed

    Soleimani, Sajjad; Dubini, Gabriele; Pennati, Giancarlo

    2016-06-01

    It is important to thoroughly remove the thrombus within the course of aspiration thrombectomy; otherwise, it may lead to further embolization. The performance of the aspiration thrombectomy device with a generic geometry is studied through the computational approach. In order to model the thrombus aspiration, a real left coronary artery is chosen while thrombi with various sizes are located at the bifurcation area of the coronary artery and, depending on the size of the thrombus, it is stretched toward the side branches. The thrombus occupies the artery resembling the blood current obstruction in the coronary vessel similar to the situation that leads to heart attack. It is concluded that the aspiration ability of the thrombectomy device is not linked to the thrombus size; it is rather linked to the aspiration pressure and thrombus age (organized versus fresh thrombus). However, the aspiration time period correlates to the thrombus size. The minimum applicable aspiration pressure is also investigated in this study.

  1. YinYang atom: a simple combined ab initio quantum mechanical molecular mechanical model.

    PubMed

    Shao, Yihan; Kong, Jing

    2007-05-10

    A simple interface is proposed for combined quantum mechanical (QM) molecular mechanical (MM) calculations for the systems where the QM and MM regions are connected through covalent bonds. Within this model, the atom that connects the two regions, called YinYang atom here, serves as an ordinary MM atom to other MM atoms and as a hydrogen-like atom to other QM atoms. Only one new empirical parameter is introduced to adjust the length of the connecting bond and is calibrated with the molecule propanol. This model is tested with the computation of equilibrium geometries and protonation energies for dozens of molecules. Special attention is paid on the influence of MM point charges on optimized geometry and protonation energy, and it is found that it is important to maintain local charge-neutrality in the MM region in order for the accurate calculation of the protonation and deprotonation energies. Overall the simple YinYang atom model yields comparable results to some other QM/MM models.

  2. Manual Aspiration Thrombectomy with Stent Placement: Rapid and Effective Treatment for Phlegmasia Cerulea Dolens with Impending Venous Gangrene

    SciTech Connect

    Oguzkurt, Levent Tercan, Fahri; Ozkan, Ugur

    2008-01-15

    Phlegmasia cerulea dolens is an uncommon but potentially life-threatening complication of acute deep vein thrombosis. It is an emergency and delay in treatment may cause death or loss of the patient's limb. Surgical thrombectomy is the recommended treatment in venous gangrene. Catheter-directed intrathrombus thrombolysis has been reported as successful, but it may require a lengthy infusion. Manual aspiration thrombectomy may clear the entire thrombus with no need for thrombolytic administration and provide rapid and effective treatment for patients with phlegmasia cerulea dolens with impending venous gangrene.

  3. Soluble collagen approach to a combination tannage mechanism

    USDA-ARS?s Scientific Manuscript database

    Although complex salts of Cr(III) sulfate are currently the most effective tanning agents, salts of other metals, including aluminum, have been used either alone or in combination with vegetable tannins or other organic chemicals. In the present study, the interactions of metallic sulfates, and cond...

  4. Soluble collagen approach to a combination tannage mechanism

    USDA-ARS?s Scientific Manuscript database

    Although complex salts of Cr(III) sulfate are currently the most effective tanning agents, salts of other metals, including aluminum, have been used either alone or in combination with vegetable tannins or other organic chemicals. In the present study, the interactions of aluminum sulfate, and quebr...

  5. Thrombectomy assisted by carotid stenting in acute ischemic stroke management: benefits and harms.

    PubMed

    Steglich-Arnholm, Henrik; Holtmannspötter, Markus; Kondziella, Daniel; Wagner, Aase; Stavngaard, Trine; Cronqvist, Mats E; Hansen, Klaus; Højgaard, Joan; Taudorf, Sarah; Krieger, Derk Wolfgang

    2015-12-01

    Extracranial carotid artery occlusion or high-grade stenosis with concomitant intracranial embolism causes severe ischemic stroke and shows poor response rates to intravenous thrombolysis (IVT). Endovascular therapy (EVT) utilizing thrombectomy assisted by carotid stenting was long considered risky because of procedural complexities and necessity of potent platelet inhibition-in particular following IVT. This study assesses the benefits and harms of thrombectomy assisted by carotid stenting and identifies factors associated with clinical outcome and procedural complications. Retrospective single-center analysis of 47 consecutive stroke patients with carotid occlusion or high-grade stenosis and concomitant intracranial embolus treated between September 2011 and December 2014. Benefits included early improvement of stroke severity (NIHSS ≥ 10) or complete remission within 72 h and favorable long-term outcome (mRS ≤ 2). Harms included complications during and following EVT. Mean age was 64.3 years (standard deviation ±12.5), 40 (85%) patients received IVT initially. Median NIHSS was 16 (inter-quartile range 14-19). Mean time from stroke onset to recanalization was 311 min (standard deviation ±78.0). Early clinical improvement was detected in 22 (46%) patients. Favorable outcome at 3 months occurred in 32 (68%) patients. Expedited patient management was associated with favorable clinical outcome. Two (4%) patients experienced symptomatic hemorrhage. Eight (17%) patients experienced stent thrombosis. Four (9%) patients died. Thrombectomy assisted by carotid stenting seems beneficial and reasonably safe with a promising rate of favorable outcome. Nevertheless, adverse events and complications call for additional clinical investigations prior to recommendation as clinical standard. Expeditious patient management is central to achieve good clinical outcome.

  6. Pneumomediastinum and Mediastinal Hematoma Secondary to Right Brachiocephalic Vein Thrombectomy Mimicking STEMI

    PubMed Central

    Shukla, Prem; Nivera, Noel

    2017-01-01

    A 50-year-old male with a history of hemodialysis dependent chronic kidney disease presented to our emergency department with acute midsternal crushing chest pain. Patient was diagnosed with acute anterolateral wall Myocardial Infraction due to the presence of corresponding ST segment elevations in EKG and underwent emergent cardiac catheterization which revealed normal patent coronaries without any disease. He continued to have chest pain for which CT of the chest was done which revealed pneumomediastinum with mediastinal hematoma, due to the recent attempted thrombectomy for thrombus in his right brachiocephalic vein. PMID:28804656

  7. Safety and Efficacy of Solitaire Stent Thrombectomy: Individual Patient Data Meta-Analysis of Randomized Trials.

    PubMed

    Campbell, Bruce C V; Hill, Michael D; Rubiera, Marta; Menon, Bijoy K; Demchuk, Andrew; Donnan, Geoffrey A; Roy, Daniel; Thornton, John; Dorado, Laura; Bonafe, Alain; Levy, Elad I; Diener, Hans-Christoph; Hernández-Pérez, María; Pereira, Vitor Mendes; Blasco, Jordi; Quesada, Helena; Rempel, Jeremy; Jahan, Reza; Davis, Stephen M; Stouch, Bruce C; Mitchell, Peter J; Jovin, Tudor G; Saver, Jeffrey L; Goyal, Mayank

    2016-03-01

    Recent positive randomized trials of endovascular therapy for ischemic stroke used predominantly stent retrievers. We pooled data to investigate the efficacy and safety of stent thrombectomy using the Solitaire device in anterior circulation ischemic stroke. Patient-level data were pooled from trials in which the Solitaire was the only or the predominant device used in a prespecified meta-analysis (SEER Collaboration): Solitaire FR With the Intention for Thrombectomy as Primary Endovascular Treatment (SWIFT PRIME), Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion With Emphasis on Minimizing CT to Recanalization Times (ESCAPE), Extending the Time for Thrombolysis in Emergency Neurological Deficits-Intra-Arterial (EXTEND-IA), and Randomized Trial of Revascularization With Solitaire FR Device Versus Best Medical Therapy in the Treatment of Acute Stroke Due to Anterior Circulation Large Vessel Occlusion Presenting Within Eight Hours of Symptom Onset (REVASCAT). The primary outcome was ordinal analysis of modified Rankin Score at 90 days. The primary analysis included all patients in the 4 trials with 2 sensitivity analyses: (1) excluding patients in whom Solitaire was not the first device used and (2) including the 3 Solitaire-only trials (excluding ESCAPE). Secondary outcomes included functional independence (modified Rankin Score 0-2), symptomatic intracerebral hemorrhage, and mortality. The primary analysis included 787 patients: 401 randomized to endovascular thrombectomy and 386 to standard care, and 82.6% received intravenous thrombolysis. The common odds ratio for modified Rankin Score improvement was 2.7 (2.0-3.5) with no heterogeneity in effect by age, sex, baseline stroke severity, extent of computed tomography changes, site of occlusion, or pretreatment with alteplase. The number needed to treat to reduce disability was 2.5 and for an extra patient to achieve independent outcome was 4.25 (3.29-5.99). Successful

  8. Suction Thrombectomy of Thrombotic Occlusion of the Subclavian Artery in a Case of Takayasu's Arteritis

    SciTech Connect

    Purkayastha, Sukalyan; Jayadevan, E.R.; Kapilamoorthy, T.R.; Gupta, A.K. E-mail: gupta@sctimst.ac.in

    2006-04-15

    Takayasu's arteritis, also known as pulseless disease, is a chronic inflammatory arteritis affecting large vessels, predominantly the aorta and its main branches. Vessel inflammation leads to wall thickening, fibrosis, stenosis, and thrombus formation. Percutaneous removal of arterial thrombus with the use of several devices has been reported, with mixed results. We present a case of Takayasu's arteritis with thrombotic occlusion of the subclavian artery in which pulsed urokinase injection and suction thrombectomy were used to revascularize a threatened limb and to establish the sole arterial supply to the brain.

  9. Stent-retriever thrombectomy after intravenous t-PA vs. t-PA alone in stroke.

    PubMed

    Saver, Jeffrey L; Goyal, Mayank; Bonafe, Alain; Diener, Hans-Christoph; Levy, Elad I; Pereira, Vitor M; Albers, Gregory W; Cognard, Christophe; Cohen, David J; Hacke, Werner; Jansen, Olav; Jovin, Tudor G; Mattle, Heinrich P; Nogueira, Raul G; Siddiqui, Adnan H; Yavagal, Dileep R; Baxter, Blaise W; Devlin, Thomas G; Lopes, Demetrius K; Reddy, Vivek K; du Mesnil de Rochemont, Richard; Singer, Oliver C; Jahan, Reza

    2015-06-11

    Among patients with acute ischemic stroke due to occlusions in the proximal anterior intracranial circulation, less than 40% regain functional independence when treated with intravenous tissue plasminogen activator (t-PA) alone. Thrombectomy with the use of a stent retriever, in addition to intravenous t-PA, increases reperfusion rates and may improve long-term functional outcome. We randomly assigned eligible patients with stroke who were receiving or had received intravenous t-PA to continue with t-PA alone (control group) or to undergo endovascular thrombectomy with the use of a stent retriever within 6 hours after symptom onset (intervention group). Patients had confirmed occlusions in the proximal anterior intracranial circulation and an absence of large ischemic-core lesions. The primary outcome was the severity of global disability at 90 days, as assessed by means of the modified Rankin scale (with scores ranging from 0 [no symptoms] to 6 [death]). The study was stopped early because of efficacy. At 39 centers, 196 patients underwent randomization (98 patients in each group). In the intervention group, the median time from qualifying imaging to groin puncture was 57 minutes, and the rate of substantial reperfusion at the end of the procedure was 88%. Thrombectomy with the stent retriever plus intravenous t-PA reduced disability at 90 days over the entire range of scores on the modified Rankin scale (P<0.001). The rate of functional independence (modified Rankin scale score, 0 to 2) was higher in the intervention group than in the control group (60% vs. 35%, P<0.001). There were no significant between-group differences in 90-day mortality (9% vs. 12%, P=0.50) or symptomatic intracranial hemorrhage (0% vs. 3%, P=0.12). In patients receiving intravenous t-PA for acute ischemic stroke due to occlusions in the proximal anterior intracranial circulation, thrombectomy with a stent retriever within 6 hours after onset improved functional outcomes at 90 days. (Funded

  10. Impact of Thrombus Length on Outcomes After Intra-Arterial Aspiration Thrombectomy in the THERAPY Trial.

    PubMed

    Yoo, Albert J; Khatri, Pooja; Mocco, J; Zaidat, Osama O; Gupta, Rishi; Frei, Donald; Lopes, Demetrius; Shownkeen, Harish; Berkhemer, Olvert A; Meyer, Denise; Hak, Susana S; Kuo, Sophia S; Buell, Hope; Bose, Arani; Sit, Siu Po; von Kummer, Rüdiger

    2017-07-01

    Increasing thrombus length (TL) impedes recanalization after intravenous (IV) thrombolysis. We sought to determine whether the clinical benefit of aspiration thrombectomy relative to IV r-tPA (recombinant tissue-type plasminogen activator) may be greater at longer TL. THERAPY was a randomized trial of aspiration thrombectomy plus IV r-tPA versus IV r-tPA alone in large-vessel stroke patients with prospective TL measurement ≥8 mm. In this post hoc study, we evaluated the association of TL with trial end points and potential endovascular treatment effect, using univariate, multivariable, and multiplicative interaction analyses. TL data were available for all 108 patients (28% internal carotid artery, 62% M1, and 10% M2). Median TL was 14.0 mm (interquartile range, 9.7-19.5 mm). Longer TL was associated with worse outcome (90-day modified Rankin Scale score: odds ratio, 1.24 per 5-mm TL increment; 95% confidence interval, 1.04-1.52; P=0.02), even after adjusting for key outcome predictors (adjusted P=0.004). Longer TL was also associated with more serious adverse events (adjusted P=0.01), more symptomatic hemorrhages (adjusted P=0.03), and increased mortality (adjusted P=0.01). No significant relationship was observed between TL and angiographic reperfusion (modified thrombolysis in cerebral ischemia 2b-3), but greater TL was associated with longer endovascular procedural times (ρ=0.36; P=0.045). Increasing TL was associated with greater aspiration thrombectomy treatment effect (interaction term P=0.03). This might be related to a potentially stronger adverse effect of increasing TL on 90-day modified Rankin Scale for patients treated with IV r-tPA (ρ=0.39; P=0.01) compared with intra-arterial therapy (ρ=0.20; P=0.165). Ischemic stroke patients with longer symptomatic thrombi have worse 90-day clinical outcomes but may have a greater relative benefit of aspiration thrombectomy over IV r-tPA alone. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01429350

  11. Pharmacomechanical thrombectomy with the Castañeda brush catheter in thrombosed hemodialysis grafts and native fistulas.

    PubMed

    Heye, Sam; Van Kerkhove, Filip; Claes, Kathleen; Maleux, Geert

    2007-11-01

    To evaluate the safety and efficacy of the Castañeda brush catheter in the treatment of thrombosed hemodialysis fistulas and grafts. Twenty-six revascularization procedures with the Castañeda brush catheter combined with urokinase were retrospectively analyzed in 21 patients (mean age, 69 years; range, 35-87 y). Hemodialysis shunts were native arteriovenous (AV) fistulas (n=15; 16 procedures) or polytetrafluoroethylene grafts (n=6; 10 procedures). Major outcomes included procedure time, anatomic and clinical success rates, complication rate, and primary, primary assisted, and secondary patency. In 26 procedures, the brush catheter was used in combination with a mean dose of 239,792 IU urokinase (range, 60,000-300,000 IU). Additional angioplasty was performed in all procedures; five procedures (19%) required additional stent implantation. Mean procedure time was 99.2 minutes (range, 49-261 min). Anatomic and clinical success rates were 100% and 96.2%, respectively. Two minor complications (8%) occurred, neither of which was device-related: one case of extravasation treated by balloon tamponade and one hematoma at the distal puncture site without the need for surgery or transfusion. Primary patency rates were 87%, 62%, and 50% at 3, 6, and 12 months, respectively, for AV fistulas, and 50%, 33%, and 17%, respectively, for grafts. Assisted primary patency rates were 93%, 77%, and 70% at 3, 6, and 12 months, respectively, for AV fistulas, and 50%, 33%, and 17%, respectively, for grafts. At 3, 6, and 12 months, secondary patency rates were 93%, 85%, and 80%, respectively, for AV fistulas, and 83%, 67%, and 50%, respectively, for grafts. The Castañeda brush catheter is a safe and effective pharmacomechanical thrombectomy device for the treatment of thrombosed hemodialysis grafts and native fistulas.

  12. Combined Mechanical and Electrical Study of Polymers of Biological Origin

    NASA Astrophysics Data System (ADS)

    Zsoldos, G.; Szoda, K.; Marossy, K.

    2017-02-01

    Thermally Simulated Depolarization Current measurement is an excellent but not widely used method for identifying relaxation processes in polymers. The DMA method is used here to analyze the mechanical changes depend on temperature in biopolymers. The two techniques take advantage of the energy changes involved in the various phase transitions of certain polymer molecules. This allows for several properties of the material to be ascertained; melting points, enthalpies of melting, crystallization temperatures, glass transition temperatures and degradation temperatures. The examined biopolymer films are made from biological materials such as proteins and polysaccharides. These materials have gained wide usage in pharmaceutical, medical and food areas. The uses of biopolymer films depend on their structure and mechanical properties. This work is based on pectin and gelatin films. The films were prepared by casting. The casting technique used aqueous solutions in each case of sample preparation. The manufacturing process of the pectin and gelatin films was a single stage solving process.

  13. Connecting caddisworm silk structure and mechanical properties: combined infrared spectroscopy and mechanical analysis

    PubMed Central

    Ashton, Nicholas N.; Pan, Huaizhong; Stewart, Russell J.

    2016-01-01

    The underwater silk of an aquatic casemaking caddisfly larvae (Hesperophylax occidentalis) is viscoelastic, and displays distinct yield behaviour, large strain cycle hysteresis and near complete recovery of its initial strength and stiffness when unloaded. Yield followed by a stress plateau has been attributed to sequential rupture of serial Ca2+-cross-linked phosphoserine (pS) β-domains. Spontaneous recovery has been attributed to refolding of the Ca2+/pS domains powered by an elastic network. In this study, native Ca2+ ions were exchanged with other metal ions, followed by combined mechanical and FTIR analysis to probe the contribution of pS/metal ion complexes to silk mechanical properties. After exchange of Ca2+ with Na+, the fibres are soft elastomers and the infrared spectra are consistent with Cv3 symmetry of the – groups. Multivalent metal ions decreased the – symmetry and the symmetric stretching modes (vs) split in a manner characteristic of ordered phosphate compounds, such as phosphate minerals and lamellar bilayers of phosphatidic acid lipids. Integrated intensities of the vs bands, indicative of the metal ion's effect on transition dipole moment of the P–O bonds, and thereby the strength of the phosphate metal complex, increased in the order: Na+ < Mg2+ < Sr2+ < Ba2+ < Ca2+ < Eu3+ < La3+ < Zn2+ < Fe2+. With a subset of the metal ion series, the initial stiffness and yield stress of metal ion-exchanged fibres increased in the same order: establishing the link between phosphate transition dipole moments and silk fibre strength. PMID:27278649

  14. Connecting caddisworm silk structure and mechanical properties: combined infrared spectroscopy and mechanical analysis.

    PubMed

    Ashton, Nicholas N; Pan, Huaizhong; Stewart, Russell J

    2016-06-01

    The underwater silk of an aquatic casemaking caddisfly larvae (Hesperophylax occidentalis) is viscoelastic, and displays distinct yield behaviour, large strain cycle hysteresis and near complete recovery of its initial strength and stiffness when unloaded. Yield followed by a stress plateau has been attributed to sequential rupture of serial Ca(2+)-cross-linked phosphoserine (pS) β-domains. Spontaneous recovery has been attributed to refolding of the Ca(2+)/pS domains powered by an elastic network. In this study, native Ca(2+) ions were exchanged with other metal ions, followed by combined mechanical and FTIR analysis to probe the contribution of pS/metal ion complexes to silk mechanical properties. After exchange of Ca(2+) with Na(+), the fibres are soft elastomers and the infrared spectra are consistent with Cv3 symmetry of the -[Formula: see text] groups. Multivalent metal ions decreased the -[Formula: see text] symmetry and the symmetric stretching modes (vs) split in a manner characteristic of ordered phosphate compounds, such as phosphate minerals and lamellar bilayers of phosphatidic acid lipids. Integrated intensities of the vs bands, indicative of the metal ion's effect on transition dipole moment of the P-O bonds, and thereby the strength of the phosphate metal complex, increased in the order: Na(+) < Mg(2+) < Sr(2+) < Ba(2+) < Ca(2+) < Eu(3+) < La(3+) < Zn(2+) < Fe(2+) With a subset of the metal ion series, the initial stiffness and yield stress of metal ion-exchanged fibres increased in the same order: [Formula: see text] [Formula: see text] establishing the link between phosphate transition dipole moments and silk fibre strength. © 2016 The Authors.

  15. Combined holographic-mechanical optical tweezers: construction, optimization, and calibration.

    PubMed

    Hanes, Richard D L; Jenkins, Matthew C; Egelhaaf, Stefan U

    2009-08-01

    A spatial light modulator (SLM) and a pair of galvanometer-mounted mirrors (GMM) were combined into an optical tweezers setup. This provides great flexibility as the SLM creates an array of traps, which can be moved smoothly and quickly with the GMM. To optimize performance, the effect of the incidence angle on the SLM with respect to phase and intensity response was investigated. Although it is common to use the SLM at an incidence angle of 45 degrees, smaller angles give a full 2pi phase shift and an output intensity which is less dependent on the magnitude of the phase shift. The traps were calibrated using an active oscillatory technique and a passive probability distribution method.

  16. Combined holographic-mechanical optical tweezers: Construction, optimization, and calibration

    SciTech Connect

    Hanes, Richard D. L.; Jenkins, Matthew C.; Egelhaaf, Stefan U.

    2009-08-15

    A spatial light modulator (SLM) and a pair of galvanometer-mounted mirrors (GMM) were combined into an optical tweezers setup. This provides great flexibility as the SLM creates an array of traps, which can be moved smoothly and quickly with the GMM. To optimize performance, the effect of the incidence angle on the SLM with respect to phase and intensity response was investigated. Although it is common to use the SLM at an incidence angle of 45 deg., smaller angles give a full 2{pi} phase shift and an output intensity which is less dependent on the magnitude of the phase shift. The traps were calibrated using an active oscillatory technique and a passive probability distribution method.

  17. Combining two proven mechanical tenderness measurements in one steak.

    PubMed

    Callahan, Z D; Belk, K E; Miller, R K; Morgan, J B; Lorenzen, C L

    2013-09-01

    This research was performed to determine the true efficacy of measuring both Warner-Bratzler shear force (WBSF) and slice shear force (SSF) in the same steak. The objectives were to compare cooking methods commonly used in preparing steaks for WBSF and SSF procedures and compare them at different cooling times. United States Department of Agriculture select strip loins (n = 240) were aged for either 7 or 14 d to increase the variation in tenderness. Each strip loin was then frozen and cut into 2.54-cm steaks. Steaks were then cooked to an internal temperature of 71°C using a convection conveyor oven (conveyor), a convection oven, clamshell grill, or an open hearth grill. Steaks were allotted to 4 different cooling times to create the combinations of: WBSF 4 h/SSF 0 h, WBSF 4 h/SSF 4 h, WBSF 24 h/SSF 0 h, WBSF 24 h/SSF 24 h. Five 1.25-cm cores were used for WBSF and one 1- by 5-cm slice for SSF. The WBSF from steaks cooked with conveyor were tougher than convection oven cooked steaks [51.9 Newtons (N) vs. 46.1 N; P < 0.05]. However, SSF were tougher when cooked in oven compared with those cooked in conveyor (267.5 N vs. 237.2 N; P < 0.05). Correlations for WBSF and SSF performed in the same steak ranged from 0.51 to 0.88 (P < 0.0001). The WBSF 24 h/SSF 0 h and WBSF 4 h/SSF 4 h had the strongest relationships (0.88 and 0.82, respectively; P < 0.05) between WBSF and SSF when using clamshell method. Performing WBSF and SSF in the same steak was successful based on moderate to high correlation values but the magnitude of the relationship is dependent on the combination of cooking method and cooling time.

  18. Development of a surgical safety checklist for the performance of radical nephrectomy and tumor thrombectomy

    PubMed Central

    2012-01-01

    Background The surgical management of renal cell carcinoma with invasion of the renal vein or inferior vena cava is associated with significant rates of perioperative morbidity and mortality. In this report we propose a surgical checklist aimed at reducing adverse events associated with the resection of these tumors. Methods This review describes the development of an evidence- and experience-based surgical checklist aimed at improving the perioperative safety of patients undergoing radical nephrectomy and tumor thrombectomy. Results Reducing the risk of complications during the surgical management of renal tumors with venous invasion begins with appropriate pre-operative imaging aimed at defining the cranial extent of the tumor thrombus, thus facilitating accurate preoperative planning. Other key elements of the checklist are aimed at ensuring clear and precise pre-, intra- and postoperative communication between members of the multidisciplinary-care team. Conclusion A standardized surgical checklist may help to increase the perioperative safety of patients undergoing radical nephrectomy and tumor thrombectomy. Future validation studies are required to determine the clinical feasibility and post-implementation safety profile of this new checklist. PMID:23241448

  19. Percutaneous Introducibility of the Expandable Vascular Sheath System and Injury Potential of Balloon-Assisted Thrombectomy: Preliminary In Vivo Results

    SciTech Connect

    Brossmann, Joachim; Haghighi, Parviz; Bookstein, Joseph J.

    1999-01-15

    Purpose: To test the percutaneous introducibility of the expandable vascular sheath (EVS) system and the safety of percutaneous balloon-assisted thrombectomy. Methods: The EVS was inserted directly (n= 9) or through a 9.5 Fr regular vascular introducer sheath (n= 9) into the femoral arteries and veins and carotid arteries in four dogs (18-21 kg). Balloon-assisted thrombectomies were simulated in iliac arteries. Histologic examinations were done at sites of funnel deployment immediately (n= 4) and 25 days (n= 8) after the intervention. Results: The EVS was successfully introduced into six of nine vessels by a direct percutaneous approach. Balloon-assisted thrombectomy using the EVS device caused localized intimal denudation, disruption of the internal elastic lamina, and mild hemorrhages into the media; one arterial dissection at the site of funnel deployment was seen. All indirect insertions and funnel deployments were successful. Twenty-five days after the experiments, intimal hyperplasia was noted in all cases. Conclusion: Percutaneous balloon-assisted thrombectomy may cause mild vascular injuries. Direct percutaneous introduction of the EVS device cannot be recommended yet.

  20. Treating electrostatics with Wolf summation in combined quantum mechanical and molecular mechanical simulations

    NASA Astrophysics Data System (ADS)

    Ojeda-May, Pedro; Pu, Jingzhi

    2015-11-01

    The Wolf summation approach [D. Wolf et al., J. Chem. Phys. 110, 8254 (1999)], in the damped shifted force (DSF) formalism [C. J. Fennell and J. D. Gezelter, J. Chem. Phys. 124, 234104 (2006)], is extended for treating electrostatics in combined quantum mechanical and molecular mechanical (QM/MM) molecular dynamics simulations. In this development, we split the QM/MM electrostatic potential energy function into the conventional Coulomb r-1 term and a term that contains the DSF contribution. The former is handled by the standard machinery of cutoff-based QM/MM simulations whereas the latter is incorporated into the QM/MM interaction Hamiltonian as a Fock matrix correction. We tested the resulting QM/MM-DSF method for two solution-phase reactions, i.e., the association of ammonium and chloride ions and a symmetric SN2 reaction in which a methyl group is exchanged between two chloride ions. The performance of the QM/MM-DSF method was assessed by comparing the potential of mean force (PMF) profiles with those from the QM/MM-Ewald and QM/MM-isotropic periodic sum (IPS) methods, both of which include long-range electrostatics explicitly. For ion association, the QM/MM-DSF method successfully eliminates the artificial free energy drift observed in the QM/MM-Cutoff simulations, in a remarkable agreement with the two long-range-containing methods. For the SN2 reaction, the free energy of activation obtained by the QM/MM-DSF method agrees well with both the QM/MM-Ewald and QM/MM-IPS results. The latter, however, requires a greater cutoff distance than QM/MM-DSF for a proper convergence of the PMF. Avoiding time-consuming lattice summation, the QM/MM-DSF method yields a 55% reduction in computational cost compared with the QM/MM-Ewald method. These results suggest that, in addition to QM/MM-IPS, the QM/MM-DSF method may serve as another efficient and accurate alternative to QM/MM-Ewald for treating electrostatics in condensed-phase simulations of chemical reactions.

  1. Treating electrostatics with Wolf summation in combined quantum mechanical and molecular mechanical simulations

    SciTech Connect

    Ojeda-May, Pedro; Pu, Jingzhi

    2015-11-07

    The Wolf summation approach [D. Wolf et al., J. Chem. Phys. 110, 8254 (1999)], in the damped shifted force (DSF) formalism [C. J. Fennell and J. D. Gezelter, J. Chem. Phys. 124, 234104 (2006)], is extended for treating electrostatics in combined quantum mechanical and molecular mechanical (QM/MM) molecular dynamics simulations. In this development, we split the QM/MM electrostatic potential energy function into the conventional Coulomb r{sup −1} term and a term that contains the DSF contribution. The former is handled by the standard machinery of cutoff-based QM/MM simulations whereas the latter is incorporated into the QM/MM interaction Hamiltonian as a Fock matrix correction. We tested the resulting QM/MM-DSF method for two solution-phase reactions, i.e., the association of ammonium and chloride ions and a symmetric SN{sub 2} reaction in which a methyl group is exchanged between two chloride ions. The performance of the QM/MM-DSF method was assessed by comparing the potential of mean force (PMF) profiles with those from the QM/MM-Ewald and QM/MM-isotropic periodic sum (IPS) methods, both of which include long-range electrostatics explicitly. For ion association, the QM/MM-DSF method successfully eliminates the artificial free energy drift observed in the QM/MM-Cutoff simulations, in a remarkable agreement with the two long-range-containing methods. For the SN{sub 2} reaction, the free energy of activation obtained by the QM/MM-DSF method agrees well with both the QM/MM-Ewald and QM/MM-IPS results. The latter, however, requires a greater cutoff distance than QM/MM-DSF for a proper convergence of the PMF. Avoiding time-consuming lattice summation, the QM/MM-DSF method yields a 55% reduction in computational cost compared with the QM/MM-Ewald method. These results suggest that, in addition to QM/MM-IPS, the QM/MM-DSF method may serve as another efficient and accurate alternative to QM/MM-Ewald for treating electrostatics in condensed-phase simulations of chemical

  2. Treating electrostatics with Wolf summation in combined quantum mechanical and molecular mechanical simulations.

    PubMed

    Ojeda-May, Pedro; Pu, Jingzhi

    2015-11-07

    The Wolf summation approach [D. Wolf et al., J. Chem. Phys. 110, 8254 (1999)], in the damped shifted force (DSF) formalism [C. J. Fennell and J. D. Gezelter, J. Chem. Phys. 124, 234104 (2006)], is extended for treating electrostatics in combined quantum mechanical and molecular mechanical (QM/MM) molecular dynamics simulations. In this development, we split the QM/MM electrostatic potential energy function into the conventional Coulomb r(-1) term and a term that contains the DSF contribution. The former is handled by the standard machinery of cutoff-based QM/MM simulations whereas the latter is incorporated into the QM/MM interaction Hamiltonian as a Fock matrix correction. We tested the resulting QM/MM-DSF method for two solution-phase reactions, i.e., the association of ammonium and chloride ions and a symmetric SN2 reaction in which a methyl group is exchanged between two chloride ions. The performance of the QM/MM-DSF method was assessed by comparing the potential of mean force (PMF) profiles with those from the QM/MM-Ewald and QM/MM-isotropic periodic sum (IPS) methods, both of which include long-range electrostatics explicitly. For ion association, the QM/MM-DSF method successfully eliminates the artificial free energy drift observed in the QM/MM-Cutoff simulations, in a remarkable agreement with the two long-range-containing methods. For the SN2 reaction, the free energy of activation obtained by the QM/MM-DSF method agrees well with both the QM/MM-Ewald and QM/MM-IPS results. The latter, however, requires a greater cutoff distance than QM/MM-DSF for a proper convergence of the PMF. Avoiding time-consuming lattice summation, the QM/MM-DSF method yields a 55% reduction in computational cost compared with the QM/MM-Ewald method. These results suggest that, in addition to QM/MM-IPS, the QM/MM-DSF method may serve as another efficient and accurate alternative to QM/MM-Ewald for treating electrostatics in condensed-phase simulations of chemical reactions.

  3. Discovery, mechanisms of action and combination therapy of artemisinin

    PubMed Central

    Cui, Liwang; Su, Xin-zhuan

    2009-01-01

    Despite great international efforts, malaria still inflicts an enormous toll on human lives, especially in Africa. Throughout history, antimalarial medicines have been one of the most powerful tools in malaria control. However, the acquisition and spread of parasite strains that are resistant to multiple antimalarial drugs have become one of the greatest challenges to malaria treatment, and are associated with the increase in morbidity and mortality in many malaria-endemic countries. To deal with this grave situation, artemisinin-based combinatory therapies (ACTs) have been introduced and widely deployed in malarious regions. Artemisinin is a new class of antimalarial compounds discovered by Chinese scientists from the sweet wormwood Artemisia annua. The potential development of resistance to artemisinins by Plasmodium falciparum threatens the usable lifespan of ACTs, and therefore is a subject of close surveillance and extensive research. Studies at the Thai–Cambodian border, a historical epicenter of multidrug resistance, have detected reduced susceptibility to artemisinins as manifested by prolonged parasite-clearance times, raising considerable concerns on resistance development. Despite this significance, there is still controversy on the mode of action of artemisinins. Although a number of potential cellular targets of artemisinins have been proposed, they remain to be verified experimentally. Here, we review the history of artemisinin discovery, discuss the mode of action and potential drug targets, and present strategies to elucidate resistance mechanisms. PMID:19803708

  4. Mechanical analysis of PA66 under combined shear-compression

    NASA Astrophysics Data System (ADS)

    Duan, Qian; Jin, Tao; Chen, Shengjia; Shu, Xuefeng

    2017-05-01

    The large-strain mechanical behavior of PA66 was investigated using shear-compression specimens (SCS) with two opposite slots machined at different angles (15°, 30°, 45°, and 50°). Results show that strain rate and slot angle affect the equivalent stress in different levels. Slot angle sensitivity affects both flow stress and hardening characteristics, and strain rate influences elastic deformation. Increasing the strain rate gradually increases the equivalent stress. SCS with a slot angle of 30° exhibits the largest equivalent stress and the greatest effect of strain rate. The stress-strain curve differs between cylindrical specimens and SCS under quasi-static conditions. The yield stress obtained by the cylindrical specimens is higher than that of SCS. A constitutive model is modified based on the Drucker-Prager criterion to describe the effect of hydrostatic pressure and strain rate on the equivalent yield stress of polymer materials. The theoretical formula predictions are consistent with experimental results, thereby confirming the feasibility of this constitutive relationship.

  5. Discovery, mechanisms of action and combination therapy of artemisinin.

    PubMed

    Cui, Liwang; Su, Xin-zhuan

    2009-10-01

    Despite great international efforts, malaria still inflicts an enormous toll on human lives, especially in Africa. Throughout history, antimalarial medicines have been one of the most powerful tools in malaria control. However, the acquisition and spread of parasite strains that are resistant to multiple antimalarial drugs have become one of the greatest challenges to malaria treatment, and are associated with the increase in morbidity and mortality in many malaria-endemic countries. To deal with this grave situation, artemisinin-based combinatory therapies (ACTs) have been introduced and widely deployed in malarious regions. Artemisinin is a new class of antimalarial compounds discovered by Chinese scientists from the sweet wormwood Artemisia annua. The potential development of resistance to artemisinins by Plasmodium falciparum threatens the usable lifespan of ACTs, and therefore is a subject of close surveillance and extensive research. Studies at the Thai-Cambodian border, a historical epicenter of multidrug resistance, have detected reduced susceptibility to artemisinins as manifested by prolonged parasite-clearance times, raising considerable concerns on resistance development. Despite this significance, there is still controversy on the mode of action of artemisinins. Although a number of potential cellular targets of artemisinins have been proposed, they remain to be verified experimentally. Here, we review the history of artemisinin discovery, discuss the mode of action and potential drug targets, and present strategies to elucidate resistance mechanisms.

  6. Laser-activated shape memory polymer intravascular thrombectomy device

    NASA Astrophysics Data System (ADS)

    Small, Ward, IV; Wilson, Thomas S.; Benett, William J.; Loge, Jeffrey M.; Maitland, Duncan J.

    2005-10-01

    A blood clot (thrombus) that becomes lodged in the arterial network supplying the brain can cause an ischemic stroke, depriving the brain of oxygen and often resulting in permanent disability. As an alternative to conventional clot-dissolving drug treatment, we are developing an intravascular laser-activated therapeutic device using shape memory polymer (SMP) to mechanically retrieve the thrombus and restore blood flow to the brain. Thermal imaging and computer simulation were used to characterize the optical and photothermal behavior of the SMP microactuator. Deployment of the SMP device in an in vitro thrombotic vascular occlusion model demonstrated the clinical treatment concept.

  7. Hounsfield unit value and clot length in the acutely occluded vessel and time required to achieve thrombectomy, complications and outcome.

    PubMed

    Spiotta, Alejandro M; Vargas, Jan; Hawk, Harris; Turner, Raymond; Chaudry, M Imran; Battenhouse, Holly; Turk, Aquilla S

    2014-07-01

    Intra-arterial therapy for acute ischemic stroke (AIS) now has an established role. We investigated if Hounsfield Units (HU) quantification on non-contrast CT is associated with ease and efficacy of mechanical thrombectomy and outcomes. We retrospectively studied a prospectively maintained database of cases of AIS given intra-arterial therapy between May 2008 and August 2012. Functional outcome was assessed by 90-day follow-up modified Rankin Scale (mRS). Patients were dichotomized based on time to recanalization. HU were calculated on head CT and thrombus location and length were determined on CT angiography. Simple linear regression was used to analyze the association between clot length, average HU and other clinical variables. 141 patients were included. There was no difference in clot length or average HU among patients with good recanalization achieved within 1 h and those in which the procedures extended beyond 1 h. There was no relationship between clot length or density and recanalization. The thrombus length and density were not significantly different between patients with procedural complications and those without. Neither the presence of post-procedure intracranial hemorrhage nor the 90-day mRS was associated with thrombus length or density. We have not found any significant associations between either thrombus length or density and likelihood of recanalization, time to achieve recanalization, intraprocedural complications, postprocedural hemorrhage or functional outcome at 90 days. These results do not support a predictive value for thrombus quantification in the evaluation of AIS. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  8. Resizing procedure for optimum design of structures under combined mechanical and thermal loading

    NASA Technical Reports Server (NTRS)

    Adelman, H. M.; Narayanaswami, R.

    1976-01-01

    An algorithm is reported for resizing structures subjected to combined thermal and mechanical loading. The algorithm is applicable to uniaxial stress elements (rods) and membrane biaxial stress members. Thermal Fully Stressed Design (TFSD) is based on the basic difference between mechanical and thermal stresses in their response to resizing. The TFSD technique is found to converge in fewer iterations than ordinary fully stressed design for problems where thermal stresses are comparable to the mechanical stresses. The improved convergence is demonstrated by example with a study of a simplified wing structure, built-up with rods and membranes and subjected to a combination of mechanical loads and a three dimensional temperature distribution.

  9. A path-independent integral for fracture of solids under combined electrochemical and mechanical loadings

    NASA Astrophysics Data System (ADS)

    Haftbaradaran, Hamed; Qu, Jianmin

    2014-11-01

    In this study, we first demonstrate that the J-integral in classical linear elasticity becomes path-dependent when the solid is subjected to combined electrical, chemical and mechanical loadings. We then construct an electro-chemo-mechanical J-integral that is path-independent under such combined multiple driving forces. Further, we show that this electro-chemo-mechanical J-integral represents the rate at which the grand potential releases per unit crack growth. As an example, the path-independent nature of the electro-chemo-mechanical J-integral is demonstrated by solving the problem of a thin elastic film delaminated from a thick elastic substrate.

  10. Oscillating probe aspiration thrombectomy: comparative in vitro evaluation of two concepts.

    PubMed

    Schmitz-Rode, T; Günther, R W

    1992-01-01

    Aspiration thrombectomy supported by an oscillating metal probe within the catheter allows continuous aspiration of large thrombi without catheter obstruction. Thrombus aspiration assisted by an ultrasound-driven probe (frequency 26 kHz) and by an electric motor-driven probe (frequency 40 Hz) was compared in two different in vitro models: aspiration of large clots from a Petri dish and recanalization of thrombotic occlusions in a flow model. Comparable results were found for a 1 mm ultrasound-driven probe and a 0.5 mm motor-driven probe. The motor-driven device, however, seems to be more appealing for in vivo application because of its simplicity, probe flexibility, absence of thermal effects, and low cost.

  11. Successful interventional thrombectomy of a basilar artery thrombus in a long-term LVAD patient.

    PubMed

    Zerdzitzki, Matthaeus; Schmid, Christof; Hirt, Stephan; Wendl, Christina; Schlachetzki, Felix; Camboni, Daniele

    2015-01-01

    Cerebral thromboembolism builds the Achilles heel for patients on left ventricular support (LVAD). Thrombolytic therapy is usually contraindicated considering the increased risk of intracranial hemorrhage in patients with LVAD under therapeutic oral anticoagulation with concomitant platelet inhibition. We report on an alternative approach to this dilemma. On day 1,091 of LVAD support (INCOR Berlin Heart), a 69 year-old male patient was admitted to a rural hospital unconscious with a left-sided hemiplegia. Cerebral computed tomography (CT) with CT angiography revealed a thromboembolic distal basilar artery occlusion. The patient was immediately transported to our medical center, where an interventional thrombectomy restored full patency of the vessel. The patient recovered without neurologic sequelae within days. This case highlights the fact that patients on LVAD support with a neurologic event should be immediately transferred to a neurovascular center for appropriate treatment including a neurointervention.

  12. A Hybrid Approach to Composite Damage and Failure Analysis Combining Synergistic Damage Mechanics and Peridynamics

    DTIC Science & Technology

    2017-06-30

    to Composite Damage and Failure Analysis Combining Synergistic Damage Mechanics and Peridynamics Sb. GRANT NUMBER N00014- l6- l -2 173 Sc. PROGRAM... Composite Damage and Failure Analysis Combining Synergistic Damage Mechanics and Peridynamics A ward Number 1\\00014-1 6-1-2173 DOD - NAVY -Office of...of interface bonds between different phases in a composite . Task 1.2 Ply level constrained cracking Task 1.1 dealt with initiation of micro-level

  13. Successful treatment of extensive cerebral venous sinus thrombosis using a combined approach with Penumbra aspiration system and Solitaire FR retrieval device

    PubMed Central

    Raychev, Radoslav; Tateshima, Satoshi; Rastogi, Sachin; Balgude, Amit; Yafeh, Banafsheh; Saver, Jeffrey L; Vespa, Paul M; Buitrago, Manuel; Duckwiler, Gary

    2013-01-01

    We present a young woman with rapidly progressive neurologic decline in the setting of malignant cerebral edema due to extensive superior sagittal sinus thrombosis and cortical venous thrombosis despite intravenous heparin administration. Complete revascularization of the occluded sinus was achieved using suction thrombectomy with the 5 max Penumbra catheter in combination with the Solitaire FR clot retrieval device. The successful endovascular treatment halted the progression of her cerebral edema, and the patient eventually had an excellent recovery after prolonged intensive medical therapy. To our knowledge, this is the first reported case describing such a combined mechanical approach for cerebral venous sinus thrombosis. The clot retrieval properties of the Solitaire device combined with direct aspiration via the newest generation Penumbra catheters may allow more rapid, safe and efficient revascularization than all previously reported endovascular treatments for this potentially devastating condition. PMID:24022899

  14. Fabrication of microfibrillated cellulose gel from waste pulp sludge via mild maceration combined with mechanical shearing

    Treesearch

    Nusheng Chen; Junyong Zhu; Zhaohui Tong

    2016-01-01

    This article describes a facile route, which combines mild maceration of waste pulp sludge and a mechanical shearing process, to prepare microfibrillated cellulose (MFC) with a high storage modulus. In the maceration, the mixture of glacial acetic acid and hydrogen peroxide was used to extract cellulose from never-dried waste pulp sludge. Then, two different mechanical...

  15. The effect of combined mechanism ankle support on postural control of patients with chronic ankle instability.

    PubMed

    Hadadi, Mohammad; Ebrahimi, Ismaeil; Mousavi, Mohammad Ebrahim; Aminian, Gholamreza; Esteki, Ali; Rahgozar, Mehdi

    2017-02-01

    Chronic ankle instability is associated with neuromechanical changes and poor postural stability. Despite variety of mechanisms of foot and ankle orthoses, almost none apply comprehensive mechanisms to improve postural control in all subgroups of chronic ankle instability patients. The purpose of this study was to investigate the effect of an ankle support implementing combined mechanisms to improve postural control in chronic ankle instability patients. Cross-sectional study. An ankle support with combined mechanism was designed based on most effective action mechanisms of foot and ankle orthoses. The effect of this orthosis on postural control was evaluated in 20 participants with chronic ankle instability and 20 matched healthy participants. The single-limb stance balance test was measured in both groups with and without the new orthosis using a force platform. The results showed that application of combined mechanism ankle support significantly improved all postural sway parameters in chronic ankle instability patients. There were no differences in means of investigated parameters with and without the orthosis in the healthy group. No statistically significant differences were found in postural sway between chronic ankle instability patients and healthy participants after applying the combined mechanism ankle support. The combined mechanism ankle support is effective in improving static postural control of chronic ankle instability patients to close to the postural sway of healthy individual. the orthosis had no adverse effects on balance performance of healthy individuals. Clinical relevance Application of the combined mechanism ankle support for patients with chronic ankle instability is effective in improving static balance. This may be helpful in reduction of recurrence of ankle sprain although further research about dynamic conditions is needed.

  16. A Hybrid Approach to Composite Damage and Failure Analysis Combining Synergistic Damage Mechanics and Peridynamics

    DTIC Science & Technology

    2016-03-31

    Damage and Failure Analysis Combining Synergistic Damage Mechanics and Peridynamics 5b. GRANT NUMBER N00014-1 6-1-2173 5c. PROGRAM ELEMENT NUMBER 6...Damage Mechanics and Peridynamics Award Number N00014-16-1-2173 DOD - NAVY- Office of Naval Research PI: Ramesh Talreja Co-PI: Florin Bobaru Executive...local stress states are responsible for the precursor mechanisms that initiate cracks. This task studies the point-failure processes that become critical

  17. In Vitro Evaluation of a Rheolytic Thrombectomy System for Clot Removal from Five Different Temporary Vena Cava Filters

    SciTech Connect

    Buecker, Arno; Neuerburg, Joerg; Schmitz-Rode, Thomas; Vorwerk, Dierk; Guenther, Rolf W.

    1997-11-15

    Purpose: To evaluate the feasibility of thrombus removal from temporary vena cava filters using a rheolytic thrombectomy device and to assess the embolization rate of this procedure. Methods: Five temporary vena cava filters together with porcine thrombi were placed in a vena cava flow model (semitranslucent silicone tube of 23 mm diameter, pulsatile flow at a mean flow rate of 4 L/min). A rheolytic thrombectomy system (Hydrolyser) was used with a 9 Fr guiding catheter to remove the clots. The effluent was passed through filters of different size and the amount of embolized particles as well as the remaining thrombus were measured. Results: Thrombus removal rates ranged from 85% to 100%. Embolization rates between 47% and 60% were calculated for the different filters. Conclusion: The Hydrolyser is able to remove sufficiently high amounts of thrombus from temporary vena cava filters. However, the amount of embolized particles makes it impossible to utilize this method without special precautions against embolization.

  18. Acute Middle Cerebral Artery Occlusion Treated by Thrombectomy in a Patient with Myelodysplastic Syndrome and Severe Thrombocytopenia

    PubMed Central

    Onder, Halil; Murat Arsava, E.; Arat, Anıl; Akif Topcuoglu, M.

    2015-01-01

    Objective Experience on thrombolysis and/or thrombectomy for acute major ischemic strokes in the setting of deep (less than 40,000/mm3) thrombocytopenia is limited. Methods Case report and review of the literature. Results A 63-year-old female with myelodysplastic syndrome presented with left middle cerebral artery stroke within 2 hours of symptom onset. Severe thrombocytopenia (10.000/mm3) precluded systemic thrombolysis. However, endovascular thrombectomy provided successful recanalization and dramatic clinical recovery with NIHSS score decreasing from 20 to 2 soon after the procedure. Her modified Rankin scale was 1 at the end of the third month. Conclusion This exceptional case highlights that neurothrombectomy could be feasible and of justifiable merit even in the setting of critically low thrombocytopenia if a meticulous procedure is followed in subjects with severe acute stroke. PMID:26576212

  19. Disaggregation of human solid tumours by combined mechanical and enzymatic methods.

    PubMed Central

    Engelholm, S. A.; Spang-Thomsen, M.; Brünner, N.; Nøhr, I.; Vindeløv, L. L.

    1985-01-01

    Two combined mechanical and enzymatic disaggregation techniques and a simple mechanical disaggregation procedure were compared. The combined procedures involved a mechanical comminution of the tumour tissue followed by incubation in trypsin. In one method, the tissue was subjected to long-term trypsinization at 4 degrees C, and in the other procedure, repeated short-term trypsinization at 37 degrees C was applied. The results were compared in terms of the yield of viable cells, plating efficiency, the ability to produce tumours in nude mice, and DNA distribution as measured by flow cytometry. The combined techniques provided reproducible cell yields of 2-10 X 10(7) viable cells g-1 of tissue, whereas only a small number of tumour cells was produced by the mechanical method. DNA analysis demonstrated that only the long-term trypsinization procedure resulted in a representative cell yield from all the tumours tested. PMID:3966975

  20. Predictive Factors for Good Outcome and Mortality After Stent-Retriever Thrombectomy in Patients With Acute Anterior Circulation Stroke

    PubMed Central

    Yoon, Woong; Kim, Seul Kee; Park, Man Seok; Baek, Byung Hyun; Lee, Yun Young

    2017-01-01

    Background and Purpose Predictive factors associated with stent-retriever thrombectomy for patients with acute anterior circulation stroke remain to be elucidated. This study aimed to investigate clinical and procedural factors predictive of good outcome and mortality after stent-retriever thrombectomy in a large cohort of patients with acute anterior circulation stroke. Methods We analyzed clinical and procedural data in 335 patients with acute anterior circulation stroke treated with stent-retriever thrombectomy. A good outcome was defined as a modified Rankin Scale score of 0 to 2 at 3 months. The associations between clinical, imaging, and procedural factors and good outcome and mortality, respectively, were evaluated using logistic regression analysis. Results Using multivariate analysis, age (odds ratio [OR], 0.965; 95% confidence interval [CI], 0.944-0.986; P=0.001), successful revascularization (OR, 4.658; 95% CI, 2.240-9.689; P<0.001), parenchymal hemorrhage (OR, 0.150; 95% CI, 0.049-0.460; P=0.001), and baseline NIHSS score (OR, 0.908; 95% CI, 0.855-0.965; P=0.002) were independent predictors of good outcome. Independent predictors of mortality were age (OR, 1.043; 95% CI, 1.002-1.086; P=0.041), successful revascularization (OR, 0.171; 95% CI, 0.079-0.370; P<0.001), parenchymal hemorrhage (OR, 2.961; 95% CI, 1.059-8.276; P=0.038), and a history of previous stroke/TIA (OR, 3.124; 95% CI, 1.340-7.281; P=0.008). Conclusions Age, revascularization status, and parenchymal hemorrhage are independent predictors of both good outcome and mortality after stent retriever thrombectomy for acute anterior circulation stroke. In addition, NIHSS score on admission is independently associated with good outcome, whereas a history of previous stroke is independently associated with mortality. PMID:28178407

  1. Stent-Retriever Thrombectomy for Acute Anterior Ischemic Stroke with Tandem Occlusion: A Systematic Review and Meta-Analysis.

    PubMed

    Sivan-Hoffmann, Rotem; Gory, Benjamin; Armoiry, Xavier; Goyal, Mayank; Riva, Roberto; Labeyrie, Paul Emile; Lukaszewicz, Anne-Claire; Lehot, Jean-Jacques; Derex, Laurent; Turjman, Francis

    2017-01-01

    To assess the efficacy and safety profile of stent-retriever thrombectomy (SRT) in acute anterior ischemic stroke patients with tandem occlusion. Using the MEDLINE database, we conducted a systematic review and meta-analysis of all studies that included patients with acute ischemic stroke attributable to tandem occlusion who received treatment with SRT between November 2010 and May 2015. The literature search identified 11 previous studies involving a total of 237 subjects out of whom 193 (81.4 %) were treated with acute stent placement for the extracranial internal carotid artery occlusion. Mean initial NIHSS score was 17, and median time from onset to recanalization was 283.5 min. Mean intravenous thrombolysis rate was 63.8 %. In the meta-analysis, the recanalization rate reached 81 % (95 % CI, 73-89). Meta-analysis of clinical outcomes showed a pooled estimate of 44 % (95 % CI, 33-55; 10 studies) for favourable outcome, 13 % (95 % CI, 8-20; 10 studies) for mortality, and 7 % (95 % CI, 2-13; eight studies) for symptomatic intracranial haemorrhage. SRT with emergency carotid stenting is associated with acceptable safety and efficacy in acute anterior stroke patients with tandem occlusion compared to natural history. However, the best modality to treat proximal stenosis is based on an individual case basis. • Stent retriever thrombectomy of tandem occlusion is efficient and safe. • Emergent carotid stenting during thrombectomy increase symptomatic intracranial haemorrhage without impact mortality. • Thrombectomy of tandem anterior circulation occlusion may be the first therapeutic option.

  2. Forced arterial suction thrombectomy with the penumbra reperfusion catheter in acute basilar artery occlusion: a retrospective comparison study in 2 Korean university hospitals.

    PubMed

    Eom, Y-I; Hwang, Y-H; Hong, J M; Choi, J W; Lim, Y C; Kang, D-H; Kim, Y-W; Kim, Y-S; Kim, S Y; Lee, J S

    2014-12-01

    A performance of forced arterial suction thrombectomy was not reported for the treatment of acute basilar artery occlusion. This study compared revascularization performance between intra-arterial fibrinolytic treatment and forced arterial suction thrombectomy with a Penumbra reperfusion catheter in patients with acute basilar artery occlusion. Fifty-seven patients with acute basilar artery occlusion were treated with intra-arterial fibrinolysis (n = 25) or forced arterial suction thrombectomy (n = 32). Baseline characteristics, successful revascularization rate, and clinical outcomes were compared between the groups. Baseline characteristics, the frequency of patients receiving intravenous recombinant tissue plasminogen activator, and mean time interval between symptom onset and femoral puncture did not differ between groups. The forced arterial suction thrombectomy group had a shorter procedure duration (75.5 minutes versus 113.3 minutes, P = .016) and higher successful revascularization rate (88% versus 60%, P = .017) than the fibrinolysis group. Fair outcome, indicated by a modified Rankin Scale 0-3, at 3 months was achieved in 34% of patients undergoing forced arterial suction thrombectomy and 8% of patients undergoing fibrinolysis (P = .019), and the mortality rate was significantly higher in the fibrinolysis group (25% versus 68%, P = .001). Multiple logistic regression analysis identified the forced arterial suction thrombectomy method as an independent predictor of fair outcome with adjustment for age, sex, initial NIHSS score, and the use of intravenous recombinant tissue plasminogen activator (odds ratio, 7.768; 95% CI, 1.246-48.416; P = .028). In acute basilar artery occlusion, forced arterial suction thrombectomy demonstrated a higher revascularization rate and improved clinical outcome compared with traditional intra-arterial fibrinolysis. Further clinical trials with the newer Penumbra catheter are warranted. © 2014 by American Journal of

  3. A systematic review and meta-analysis of randomized controlled trials of endovascular thrombectomy compared with best medical treatment for acute ischemic stroke.

    PubMed

    Balami, Joyce S; Sutherland, Brad A; Edmunds, Laurel D; Grunwald, Iris Q; Neuhaus, Ain A; Hadley, Gina; Karbalai, Hasneen; Metcalf, Kneale A; DeLuca, Gabriele C; Buchan, Alastair M

    2015-12-01

    Acute ischemic strokes involving occlusion of large vessels usually recanalize poorly following treatment with intravenous thrombolysis. Recent studies have shown higher recanalization and higher good outcome rates with endovascular therapy compared with best medical management alone. A systematic review and meta-analysis investigating the benefits of all randomized controlled trials of endovascular thrombectomy where at least 25% of patients were treated with a thrombectomy device for the treatment of acute ischemic stroke compared with best medical treatment have yet to be performed. To perform a systematic review and a meta-analysis evaluating the effectiveness of endovascular thrombectomy compared with best medical care for treatment of acute ischemic stroke. Our search identified 437 publications, from which eight studies (totaling 2423 patients) matched the inclusion criteria. Overall, endovascular thrombectomy was associated with improved functional outcomes (modified Rankin Scale 0-2) [odds ratio 1·56 (1·32-1·85), P < 0·00001]. There was a tendency toward decreased mortality [odds ratio 0·84 (0·67-1·05), P = 0·12], and symptomatic intracerebral hemorrhage was not increased [odds ratio 1·03 (0·71-1·49), P = 0·88] compared with best medical management alone. The odds ratio for a favorable functional outcome increased to 2·23 (1·77-2·81, P < 0·00001) when newer generation thrombectomy devices were used in greater than 50% of the cases in each trial. There is clear evidence for improvement in functional independence with endovascular thrombectomy compared with standard medical care, suggesting that endovascular thrombectomy should be considered the standard effective treatment alongside thombolysis in eligible patients. © 2015 The Authors. International Journal of Stroke published by John Wiley & Sons Ltd on behalf of World Stroke Organization.

  4. Conical intersections in solution: formulation, algorithm, and implementation with combined quantum mechanics/molecular mechanics method.

    PubMed

    Cui, Ganglong; Yang, Weitao

    2011-05-28

    The significance of conical intersections in photophysics, photochemistry, and photodissociation of polyatomic molecules in gas phase has been demonstrated by numerous experimental and theoretical studies. Optimization of conical intersections of small- and medium-size molecules in gas phase has currently become a routine optimization process, as it has been implemented in many electronic structure packages. However, optimization of conical intersections of small- and medium-size molecules in solution or macromolecules remains inefficient, even poorly defined, due to large number of degrees of freedom and costly evaluations of gradient difference and nonadiabatic coupling vectors. In this work, based on the sequential quantum mechanics and molecular mechanics (QM/MM) and QM/MM-minimum free energy path methods, we have designed two conical intersection optimization methods for small- and medium-size molecules in solution or macromolecules. The first one is sequential QM conical intersection optimization and MM minimization for potential energy surfaces; the second one is sequential QM conical intersection optimization and MM sampling for potential of mean force surfaces, i.e., free energy surfaces. In such methods, the region where electronic structures change remarkably is placed into the QM subsystem, while the rest of the system is placed into the MM subsystem; thus, dimensionalities of gradient difference and nonadiabatic coupling vectors are decreased due to the relatively small QM subsystem. Furthermore, in comparison with the concurrent optimization scheme, sequential QM conical intersection optimization and MM minimization or sampling reduce the number of evaluations of gradient difference and nonadiabatic coupling vectors because these vectors need to be calculated only when the QM subsystem moves, independent of the MM minimization or sampling. Taken together, costly evaluations of gradient difference and nonadiabatic coupling vectors in solution or

  5. A Hybrid Approach to Composite Damage and Failure Analysis Combining Synergistic Damage Mechanics and Peridynamics

    DTIC Science & Technology

    2016-06-30

    composites . However, this temperature can be varied. Today, resins are avai lable to do room temperature curing of thermosetting resins . Therefore, the... Composite Damage and Failure Analysis Combining Synerg istic Damage Mechanics and Peridynamics Sb. GRANT NUMBER N00014-16-1 -2 173 Sc. PROGRAM ELEMENT...by ANSI Std. Z39.18 Quarterly Progress Report, Aprill -June 30, 2016 A Hybrid Approach to Composite Damage and Failure Analysis Combining

  6. Leaf structure affects a plant's appearance: combined multiple-mechanisms intensify remarkable foliar variegation.

    PubMed

    Chen, Yun-Shiuan; Chesson, Peter; Wu, Ho-Wei; Pao, Shang-Hung; Liu, Jian-Wei; Chien, Lee-Feng; Yong, Jean W H; Sheue, Chiou-Rong

    2017-03-01

    The presence of foliar variegation challenges perceptions of leaf form and functioning. But variegation is often incorrectly identified and misinterpreted. The striking variegation found in juvenile Blastus cochinchinensis (Melastomataceae) provides an instructive case study of mechanisms and their ecophysiological implications. Variegated (white and green areas, vw and vg) and non-variegated leaves (normal green leaves, ng) of seedlings of Blastus were compared structurally with microtechniques, and characterized for chlorophyll content and fluorescence. More limited study of Sonerila heterostemon (Melastomataceae) and Kaempferia pulchra (Zingiberaceae) tested the generality of the findings. Variegation in Blastus combines five mechanisms: epidermal, air space, upper mesophyll, chloroplast and crystal, the latter two being new mechanisms. All mesophyll cells (vw, vg, ng) have functional chloroplasts with dense thylakoids. The vw areas are distinguished by flatter adaxial epidermal cells and central trichomes containing crystals, the presence of air spaces between the adaxial epidermis and a colorless spongy-like upper mesophyll containing smaller and fewer chloroplasts. The vw area is further distinguished by having the largest spongy-tissue chloroplasts and fewer stomata. Both leaf types have similar total chlorophyll content and similar  F v/F m (maximum quantum yield of PSII), but vg has significantly higher F v/F m than ng. Variegation in Sonerila and Kaempferia is also caused by combined mechanisms, including the crystal type in Kaempferia. This finding of combined mechanisms in three different species suggests that combined mechanisms may occur more commonly in nature than current understanding. The combined mechanisms in Blastus variegated leaves represent intricate structural modifications that may compensate for and minimize photosynthetic loss, and reflect changing plant needs.

  7. Comparison of energy consumptions between ultrasonic, mechanical, and combined soil washing processes.

    PubMed

    Son, Younggyu; Nam, Sanggeon; Ashokkumar, Muthupandian; Khim, Jeehyeong

    2012-05-01

    Vigorous physical effects including micro-jet and micro-streaming can be induced in heterogeneous systems by acoustic cavitation. This can be useful for the removal of pollutants from contaminated soil particles. In this study, the diesel removal efficiencies in ultrasonic, mechanical, and combined soil washing processes have been compared considering the electrical energy consumptions for these processes. The combined process showed synergistic effects for both removal efficiency and effective volume also has the advantage of a short operation time compared to the sequential processes. Thus the ultrasonic soil washing process with mechanical mixing is considered a promising technology for industrial use. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Cost-Effectiveness of Solitaire Stent Retriever Thrombectomy for Acute Ischemic Stroke

    PubMed Central

    Shireman, Theresa I.; Wang, Kaijun; Saver, Jeffrey L.; Goyal, Mayank; Bonafé, Alain; Diener, Hans-Christoph; Levy, Elad I.; Pereira, Vitor M.; Albers, Gregory W.; Cognard, Christophe; Hacke, Werner; Jansen, Olav; Jovin, Tudor G.; Mattle, Heinrich P.; Nogueira, Raul G.; Siddiqui, Adnan H.; Yavagal, Dileep R.; Devlin, Thomas G.; Lopes, Demetrius K.; Reddy, Vivek K.; de Rochemont, Richard du Mesnil; Jahan, Reza; Vilain, Katherine A.; House, John; Lee, Jin-Moo; Cohen, David J.

    2017-01-01

    Background and Purpose Clinical trials have demonstrated improved 90-day outcomes for patients with acute ischemic stroke treated with stent retriever thrombectomy plus tissue-type plasminogen activator (SST+tPA) compared with tPA. Previous studies suggested that this strategy may be cost-effective, but models were derived from pooled data and older assumptions. Methods In this prospective economic substudy conducted alongside the SWIFT-PRIME trial (Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke), in-trial costs were measured for patients using detailed medical resource utilization and hospital billing data. Utility weights were assessed at 30 and 90 days using the EuroQol-5 dimension questionnaire. Post-trial costs and life-expectancy were estimated for each surviving patient using a model based on trial data and inputs derived from a contemporary cohort of ischemic stroke survivors. Results Index hospitalization costs were $17 183 per patient higher for SST+tPA than for tPA ($45 761 versus $28 578; P<0.001), driven by initial procedure costs. Between discharge and 90 days, costs were $4904 per patient lower for SST+tPA than for tPA ($11 270 versus $16 174; P=0.014); total 90-day costs remained higher with SST+tPA ($57 031 versus $44 752; P<0.001). Higher utility values for SST+tPA led to higher in-trial quality-adjusted life years (0.131 versus 0.105; P=0.005). In lifetime projections, SST+tPA was associated with substantial gains in quality-adjusted life years (6.79 versus 5.05), cost savings of $23 203 per patient and was economically dominant when compared with tPA in 90% of bootstrap replicates. Conclusions Among patients with acute ischemic stroke enrolled in the SWIFT-PRIME trial, SST increased initial treatment costs, but was projected to improve quality-adjusted life-expectancy and reduce healthcare costs over a lifetime horizon compared with tPA. PMID:28028150

  9. Retrograde rotational thrombectomy with the Rotarex® catheter system: treatment option for an acute thrombotic occlusion of a subclavian artery

    PubMed Central

    Lichtenberg, Michael; Kaeunicke, Matthias; Lukat, Michael; Hailer, Birgit

    2011-01-01

    Purpose: The Rotarex® catheter system is an effective tool for endovascular therapy of acute occluded arteries of the lower extremities, especially for the femoral artery. The authors report the use of the Rotarex catheter system for retrograde percutaneous thrombectomy of an occluded subclavian artery. Case presentation: A 79-year-old male patient was referred because of acute pain and paleness of his left arm. Ultrasound examination and computed tomography angiography proved an occlusion of the left subclavian artery from the origin of the vessel. A retrograde recanalization was attempted using the 6F Rotarex catheter and combined with initiation of a local low-dose lytic therapy. A normal blood flow to the left arm was restored. Follow-up examination 3 months later showed a normal perfusion situation of the left upper extremity. Conclusion: The Rotarex catheter system is an effective tool for endovascular therapy of acute occluded arteries and efficacy is not restricted to the lower extremities. PMID:22102785

  10. Intracoronary abciximab and aspiration thrombectomy in patients with large anterior myocardial infarction: the INFUSE-AMI randomized trial.

    PubMed

    Stone, Gregg W; Maehara, Akiko; Witzenbichler, Bernhard; Godlewski, Jacek; Parise, Helen; Dambrink, Jan-Henk E; Ochala, Andrzej; Carlton, Trevor W; Cristea, Ecaterina; Wolff, Steven D; Brener, Sorin J; Chowdhary, Saqib; El-Omar, Magdi; Neunteufl, Thomas; Metzger, D Christopher; Karwoski, Theodore; Dizon, Jose M; Mehran, Roxana; Gibson, C Michael

    2012-05-02

    Thrombus embolization during percutaneous coronary intervention (PCI) in ST-segment elevation myocardial infarction (STEMI) is common and results in suboptimal myocardial perfusion and increased infarct size. Two strategies proposed to reduce distal embolization and improve outcomes after primary PCI are bolus intracoronary abciximab and manual aspiration thrombectomy. To determine whether bolus intracoronary abciximab, manual aspiration thrombectomy, or both reduce infarct size in high-risk patients with STEMI. Between November 28, 2009, and December 2, 2011, 452 patients presenting at 37 sites in 6 countries within 4 hours of STEMI due to proximal or mid left anterior descending artery occlusion undergoing primary PCI with bivalirudin anticoagulation were randomized in an open-label, 2 x 2 factorial design to bolus intracoronary abciximab delivered locally at the infarct lesion site vs no abciximab and to manual aspiration thrombectomy vs no thrombectomy. A 0.25-mg/kg bolus of abciximab was administered at the site of the infarct lesion via a local drug delivery catheter. Manual aspiration thrombectomy was performed with a 6 F aspiration catheter. Primary end point: infarct size (percentage of total left ventricular mass) at 30 days assessed by cardiac magnetic resonance imaging (cMRI) in the abciximab vs no abciximab groups (pooled across the aspiration randomization); major secondary end point: 30-day infarct size in the aspiration vs no aspiration groups (pooled across the abciximab randomization). Evaluable cMRI results at 30 days were present in 181 and 172 patients randomized to intracoronary abciximab vs no abciximab, respectively, and in 174 and 179 patients randomized to manual aspiration vs no aspiration, respectively. Patients randomized to intracoronary abciximab compared with no abciximab had a significant reduction in 30-day infarct size (median, 15.1%; interquartile range [IQR], 6.8%-22.7%; n = 181, vs 17.9% [IQR, 10.3%-25.4%]; n = 172; P = .03

  11. Experimental evaluation of stent retrievers’ mechanical properties and effectiveness

    PubMed Central

    Machi, Paolo; Jourdan, Franck; Ambard, Dominique; Reynaud, Cedric; Lobotesis, Kyriakos; Sanchez, Mathieu; Bonafé, Alain; Costalat, Vincent

    2017-01-01

    Background Five randomized controlled trials recently appeared in the literature demonstrating that early mechanical thrombectomy in patients with acute ischemic stroke is significantly related to an improved outcome. Stent retrievers are accepted as the most effective devices for intracranial thrombectomy. Objective To analyze the mechanical properties of stent retrievers, their behavior during retrieval, and interaction with different clots and to identify device features that might correlate with the effectiveness of thrombus removal. Materials and methods All stent retrievers available in France up to June 2015 were evaluated by mechanical and functional tests aimed at investigating the variation of their radial force and their behavior during retrieval. Devices were also tested during in vitro thrombectomies using white and red experimental thrombi produced with human blood. Functional tests and in vitro thrombectomies were conducted using a rigid 3D printed vascular model. Results Mechanical tests showed a variation in radial force during retrieval for each stent. A constant radial force during retrieval was related to continuous cohesion over the vessel wall and a higher rate of clot removal efficacy. All stent retrievers failed when interacting with white large thrombi (diameter ≥6 mm). Conclusions None of the tested devices were effective in removing white clots of large diameter (≥6 mm). Constant radial force during retrieval allows constant cohesion to the vessel wall and pressure over the clot; such features allow for a higher rate of clot removal. PMID:27016318

  12. Robust mechanisms of ventral furrow invagination require the combination of cellular shape changes

    NASA Astrophysics Data System (ADS)

    Conte, Vito; Muñoz, José J.; Baum, Buzz; Miodownik, Mark

    2009-03-01

    Ventral furrow formation in Drosophila is the first large-scale morphogenetic movement during the life of the embryo, and is driven by co-ordinated changes in the shape of individual epithelial cells within the cellular blastoderm. Although many of the genes involved have been identified, the details of the mechanical processes that convert local changes in gene expression into whole-scale changes in embryonic form remain to be fully understood. Biologists have identified two main cell deformation modes responsible for ventral furrow invagination: constriction of the apical ends of the cells (apical wedging) and deformation along their apical-basal axes (radial lengthening/shortening). In this work, we used a computer 2D finite element model of ventral furrow formation to investigate the ability of different combinations of three plausible elementary active cell shape changes to bring about epithelial invagination: ectodermal apical-basal shortening, mesodermal apical-basal lengthening/shortening and mesodermal apical constriction. We undertook a systems analysis of the biomechanical system, which revealed many different combinations of active forces (invagination mechanisms) were able to generate a ventral furrow. Two important general features were revealed. First that combinations of shape changes are the most robust to environmental and mutational perturbation, in particular those combining ectodermal pushing and mesodermal wedging. Second, that ectodermal pushing plays a big part in all of the robust mechanisms (mesodermal forces alone do not close the furrow), and this provides evidence that it may be an important element in the mechanics of invagination in Drosophila.

  13. Effects of combined mechanical stimulation on the proliferation and differentiation of pre-osteoblasts

    PubMed Central

    Kang, Kyung Shin; Lee, Seung-Jae; Lee, Haksue; Moon, Wonkyu

    2011-01-01

    We observed how combined mechanical stimuli affect the proliferation and differentiation of pre-osteoblasts. For this research, a bioreactor system was developed that can simultaneously stimulate cells with cyclic strain and ultrasound, each of which is known to effectively stimulate bone tissue regeneration. MC3T3-E1 pre-osteoblasts were chosen for bone tissue engineering due to their osteoblast-like characteristics. 3-D scaffolds were fabricated with polycaprolactone and poly-L-lactic acid using the salt leaching method. The cells were stimulated by the bioreactor with cyclic strain and ultrasound. The bioreactor was set at a frequency of 1.0 Hz and 10% strain for cyclic strain and 1.0 MHz and 30 mW/cm2 for ultrasound. Three experimental groups (ultrasound, cyclic strain, and combined stimulation) and a control group were examined. Each group was stimulated for 20 min/day. Mechanical stimuli did not affect MC3T3-E1 cell proliferation significantly up to 10 days when measured with the cell counting kit-8. However, gene expression analysis of collagen type-I, osteocalcin, RUNX2, and osterix revealed that the combined mechanical stimulation accelerated the matrix maturation of MC3T3-E1 cells. These results indicate that the combined mechanical stimulation can enhance the differentiation of pre-osteoblasts more efficiently than simple stimuli, in spite of no effect on cell proliferation. PMID:21532314

  14. [Combined hopping-superexchange mechanism of charge transfer in DNA; a model with nearest interactions].

    PubMed

    Lakhno, V D; Sultanov, V B

    2007-01-01

    In the framework of the earlier developed combined hopping-superexchange mechanism of charge transfer in DNA, a model with all nearest interactions between nucleobases is proposed. It is shown that the transfer rates for various types of nucleotide sequences calculated within this model are in a good agreement with experimental data.

  15. Clinical study on VATS combined mechanical ventilation treatment of ARDS secondary to severe chest trauma

    PubMed Central

    Qi, Yongjun

    2016-01-01

    The aim of the study was to investigate the clinical effects of microinvasive video-assisted thoracoscopic surgery (VATS) combined with mechanical ventilation in the treatment of acute respiratory distress syndrome (ARDS) secondary to severe chest trauma. A total of 62 patients with ARDS secondary to severe chest trauma were divided into the observation and control groups. The patients in the observation groups were treated with VATS combined with early mechanical ventilation while patients in the control group were treated using routine open thoracotomy combined with early mechanical ventilation. Compared to the controls, the survival rate of the observation group was significantly higher. The average operation time of the observation group was significantly shorter than that of the control group, and the incidence of complications in the perioperative period of the observation group was significantly lower than that of the control group (p<0.05). The average application time of the observation group was significantly shorter than that of the control group, and the incidence of ventilator-associated complications was significantly lower than that of the control group (p<0.05). In conclusion, a reasonable understanding of the indications and contraindications of VATS, combined with early mechanical treatment significantly improved the success rate of the treatment of ARDS patients secondary to severe chest trauma and reduced the complications. PMID:27446317

  16. Combination of fuel-cladding chemical and mechanical interactions in mixed oxide fuel pins

    SciTech Connect

    Gotzmann, O.

    1982-04-01

    Encapsulated mixed oxide fuel pins were irradiated in the Belgian reactor BR-2 under epithermal flux conditions. Of 12 pins, 5 failed. Heavy cladding corrosion and significant cladding deformation was observed in postirradiation examination. The failures are attributed to a combined action of fuel-cladding mechanical and chemical interactions, for which favorable conditions existed in these tests.

  17. In Vitro Evaluation of a New Rotational Thrombectomy Device: The Straub Rotarex Catheter

    SciTech Connect

    Zana, Katalin; Otal, Philippe; Fornet, Bela; Forrai, Gabor; Chabbert, Valerie; Smayra, Tarek; Joffre, Francis; Rousseau, Herve

    2001-09-15

    Purpose: To evaluate the efficacy of a new rotational thrombectomy device, and the procedure-related risk of particle embolization.Methods: The experiments were performed in transparent silicone tubes. The conditions of flow were as close as possible to physiological parameters. Distal embolization was detected by a mesh of nylon filters.Results: The Straub Rotarex catheter was able to remove all clots. The mean number of migrating particles larger than 1000 {mu}m was 0.17 ({+-}0.38), the mean number of 400-1000 {mu}m migrating particles was 1.08 ({+-}1.04). The mean intervention time was 67 ({+-}37) sec. The mean volume of collected liquid was 96.6 ({+-}24.7) ml.Conclusion: The in vitro results suggest that the Straub Rotarex catheter is able to remove large volumes of thrombus with a limited risk of embolization. The main limitation of our model is the absence of adhesion of the clot to the tube.

  18. Percutaneous Aspiration Thrombectomy for the Treatment of Arterial Thromboembolic Occlusions Following Percutaneous Transluminal Angioplasty

    SciTech Connect

    Schleder, Stephan; Diekmann, Matthias; Manke, Christoph; Heiss, Peter

    2015-02-15

    PurposeThis study was designed to evaluate the technical success and the early clinical outcome of patients undergoing percutaneous aspiration thrombectomy (PAT) for the treatment of arterial thromboembolism following percutaneous infrainguinal transluminal angioplasty (PTA).MethodsIn this single-center study, during a period of 7 years retrospectively, 47 patients (22 male, 47 %) with a mean age of 73 (range 53–96) years were identified in whom PAT was performed for the treatment of thromboembolic complications of infrainguinal PTA. Primary technical success was defined as residual stenosis of <50 % in diameter after sole PAT, whereas secondary technical success was defined as residual stenosis of <50 % in diameter after PAT and additional PTA and/or stenting. Clinical outcome parameters (e.g., need for further intervention, minor/major amputation) were evaluated for the 30-day postinterventional period.ResultsPrimary technical success was achieved in 64 % of patients (30/47); secondary technical success was obtained in 96 % of patients (45/47). Clinical outcome data were available in 38 patients. In 87 % of patients (33/38), there was no need for further intervention within the 30-day postinterventional period. In three patients, minor amputations were conducted due to preexisting ulcerations (Rutherford Category 5 respectively).ConclusionsPAT enables endovascular treatment of iatrogenic thromboembolic complications after PTA with good technical and early clinical results and minimal morbidity.

  19. Hydraulic analysis of the functional properties of saline-jet aspiration thrombectomy catheters

    NASA Astrophysics Data System (ADS)

    Yamauchi, Teiyu; Furui, Shigeru; Kohtake, Hiroshi; Harasawa, Arimi; Kaminaga, Tatsuro; Tanaka, Hiroko; Takeshita, Tohru

    1999-12-01

    The purpose of this paper is to clarify the functional properties of a saline-jet aspiration thrombectomy catheter based on hydraulics. This catheter, developed by the authors, aspirates intravascular thrombi by means of the effect of a high-speed jet. We have derived the relationships between Qs, Qa and pn, where Qs is the water supply rate, Qa is the water aspiration rate and pn is the negative pressure created in the distal lumen of the catheter. The relationships are represented by simple equations using c1 and c2, where c1 and c2 are coefficients proper to the catheter. We have obtained c1 and c2 experimentally for three types of catheter with different distal shapes. Two practical conclusions are derived from this study. First, making a short taper at the distal end increases the negative pressure created and is advantageous for thrombus aspiration. Second, making the diameter of the inner tube and nozzle smaller is essential for improving the aspiration ability of the catheter.

  20. A procedure for combining acoustically induced and mechanically induced loads (first passage failure design criterion)

    NASA Technical Reports Server (NTRS)

    Crowe, D. R.; Henricks, W.

    1983-01-01

    The combined load statistics are developed by taking the acoustically induced load to be a random population, assumed to be stationary. Each element of this ensemble of acoustically induced loads is assumed to have the same power spectral density (PSD), obtained previously from a random response analysis employing the given acoustic field in the STS cargo bay as a stationary random excitation. The mechanically induced load is treated as either (1) a known deterministic transient, or (2) a nonstationary random variable of known first and second statistical moments which vary with time. A method is then shown for determining the probability that the combined load would, at any time, have a value equal to or less than a certain level. Having obtained a statistical representation of how the acoustic and mechanical loads are expected to combine, an analytical approximation for defining design levels for these loads is presented using the First Passage failure criterion.

  1. Mechanical versus clinical data combination in selection and admissions decisions: a meta-analysis.

    PubMed

    Kuncel, Nathan R; Klieger, David M; Connelly, Brian S; Ones, Deniz S

    2013-11-01

    In employee selection and academic admission decisions, holistic (clinical) data combination methods continue to be relied upon and preferred by practitioners in our field. This meta-analysis examined and compared the relative predictive power of mechanical methods versus holistic methods in predicting multiple work (advancement, supervisory ratings of performance, and training performance) and academic (grade point average) criteria. There was consistent and substantial loss of validity when data were combined holistically-even by experts who are knowledgeable about the jobs and organizations in question-across multiple criteria in work and academic settings. In predicting job performance, the difference between the validity of mechanical and holistic data combination methods translated into an improvement in prediction of more than 50%. Implications for evidence-based practice are discussed. (c) 2013 APA, all rights reserved.

  2. Combination of Universal Mechanical Testing Machine with Atomic Force Microscope for Materials Research

    NASA Astrophysics Data System (ADS)

    Zhong, Jian; He, Dannong

    2015-08-01

    Surface deformation and fracture processes of materials under external force are important for understanding and developing materials. Here, a combined horizontal universal mechanical testing machine (HUMTM)-atomic force microscope (AFM) system is developed by modifying UMTM to combine with AFM and designing a height-adjustable stabilizing apparatus. Then the combined HUMTM-AFM system is evaluated. Finally, as initial demonstrations, it is applied to analyze the relationship among macroscopic mechanical properties, surface nanomorphological changes under external force, and fracture processes of two kinds of representative large scale thin film materials: polymer material with high strain rate (Parafilm) and metal material with low strain rate (aluminum foil). All the results demonstrate the combined HUMTM-AFM system overcomes several disadvantages of current AFM-combined tensile/compression devices including small load force, incapability for large scale specimens, disability for materials with high strain rate, and etc. Therefore, the combined HUMTM-AFM system is a promising tool for materials research in the future.

  3. Combination of Universal Mechanical Testing Machine with Atomic Force Microscope for Materials Research

    PubMed Central

    Zhong, Jian; He, Dannong

    2015-01-01

    Surface deformation and fracture processes of materials under external force are important for understanding and developing materials. Here, a combined horizontal universal mechanical testing machine (HUMTM)-atomic force microscope (AFM) system is developed by modifying UMTM to combine with AFM and designing a height-adjustable stabilizing apparatus. Then the combined HUMTM-AFM system is evaluated. Finally, as initial demonstrations, it is applied to analyze the relationship among macroscopic mechanical properties, surface nanomorphological changes under external force, and fracture processes of two kinds of representative large scale thin film materials: polymer material with high strain rate (Parafilm) and metal material with low strain rate (aluminum foil). All the results demonstrate the combined HUMTM-AFM system overcomes several disadvantages of current AFM-combined tensile/compression devices including small load force, incapability for large scale specimens, disability for materials with high strain rate, and etc. Therefore, the combined HUMTM-AFM system is a promising tool for materials research in the future. PMID:26265357

  4. Isobolographic analysis of the mechanisms of action of anticonvulsants from a combination effect.

    PubMed

    Matsumura, Nobuko; Nakaki, Toshio

    2014-10-15

    The nature of the pharmacodynamic interactions of drugs is influenced by the drugs׳ mechanisms of action. It has been hypothesized that drugs with different mechanisms are likely to interact synergistically, whereas those with similar mechanisms seem to produce additive interactions. In this review, we describe an extensive investigation of the published literature on drug combinations of anticonvulsants, the nature of the interaction of which has been evaluated by type I and II isobolographic analyses and the subthreshold method. The molecular targets of antiepileptic drugs (AEDs) include Na(+) and Ca(2+) channels, GABA type-A receptor, and glutamate receptors such as NMDA and AMPA/kainate receptors. The results of this review indicate that the nature of interactions evaluated by type I isobolographic analyses but not by the two other methods seems to be consistent with the above hypothesis. Type I isobolographic analyses may be used not only for evaluating drug combinations but also for predicting the targets of new drugs.

  5. Excited States and Photochemistry of Chromophores in the Photoactive Proteins Explored by the Combined Quantum Mechanical and Molecular Mechanical Calculations.

    PubMed

    Liu, Lihong; Cui, Ganglong; Fang, Wei-Hai

    2015-01-01

    A photoactive protein usually contains a unique chromophore that is responsible for the initial photoresponse and functions of the photoactive protein are determined by the interaction between the chromophore and its protein surroundings. The combined quantum mechanical and molecular mechanical (QM/MM) approach is demonstrated to be a very useful tool for exploring structures and functions of a photoactive protein with the chromophore and its protein surroundings treated by the QM and MM methods, respectively. In this review, we summarize the basic formulas of the QM/MM approach and emphasize its applications to excited states and photoreactions of chromophores in rhodopsin protein, photoactive yellow protein, and green fluorescent protein. © 2015 Elsevier Inc. All rights reserved.

  6. Long-term outcomes with aspiration thrombectomy for patients undergoing primary percutaneous coronary intervention: A meta-analysis of randomized trials.

    PubMed

    Elgendy, Akram Y; Elgendy, Islam Y; Mahmoud, Ahmed N; Bavry, Anthony A

    2017-04-13

    Randomized clinical trials that examined long-term clinical outcomes of routine aspiration thrombectomy prior to primary percutaneous coronary intervention (PCI) in patients with acute ST-segment elevation myocardial infarction have yielded different results. We hypothesized that the routine use of manual thrombus aspiration prior to primary PCI lacks long-term clinical benefits. Electronic databases were searched for randomized trials comparing routine aspiration thrombectomy and conventional PCI. We included only trials that reported clinical outcomes beyond 6 months. The primary outcome was all-cause mortality, and the secondary outcomes included major adverse cardiovascular events, re-infarction, cardiovascular mortality, and stent thrombosis (ST). A DerSimonian-Laird model was used to construct the summary estimates risk ratio (RR). We retrieved 18 trials with 20 641 ST-segment elevation myocardial infarction patients, of whom 10 331 patients underwent routine aspiration thrombectomy prior to primary PCI. At a mean follow-up of 12 months, there was no significant decrease in the risk of all-cause mortality (RR: 0.93, 95% confidence interval [CI]: 0.82-1.05, P = 0.22), major adverse cardiac events (RR: 0.95, 95% CI: 0.87-1.03, P = 0.18), re-infarction (RR: 0.95, 95% CI: 0.80-1.13, P = 0.59), cardiovascular mortality (RR: 0.80, 95% CI: 0.47-1.36, P = 0.40), or ST (RR: 0.80, 95% CI: 0.63-1.01, P = 0.06) with routine aspiration thrombectomy. Routine aspiration thrombectomy prior to primary PCI was not associated with a reduction in long-term mortality or clinical outcomes. Future randomized trials are warranted to further evaluate the role of aspiration thrombectomy in select patients and coronary lesions.

  7. Combination effect of ultrasound and shake as a mechanical action for textile cleaning.

    PubMed

    Gotoh, Keiko; Harayama, Kokoro; Handa, Keiko

    2015-01-01

    The ultrasonic cleaning of artificially soiled fabrics with and without shake was carried out in an aqueous anionic surfactant solution. The polyester, cotton and polyester/cotton (65/35) fabrics were soiled with oleic acid or carbon black as a model soil, and cleaned together with their original fabrics with applying ultrasound for 5min. The detergency and the soil redeposition were determined from the change in the Kubelka-Munk function of the soiled and original fabric surfaces due to the cleaning. For any fabric, the removal of oleic acid and carbon black from the soiled fabric and their redeposition onto the original fabric increased with increasing electric power consumption of ultrasound. When ultrasound and shake were applied at the same time, the detergency further increased for any electric power consumption. The maximum detergency obtained with combination of ultrasound 340W and shake 160spm was compared with detergency obtained with Wascator, a horizontal axis drum type washer. It was found that the ultrasound/shake combination cleaning enabled efficient removal of both soils from any fabric and the detergency of the polyester fabrics was comparable to that with Wascator. The mechanical action during the washing was evaluated by two mechanical action test pieces commercially available, which indicated that the ultrasound/shake combination cleaning provided gentle mechanical action to the fabric in comparison with the drum type washer. The SEM observations showed the damage of the fabric and fiber surfaces was negligibly small after the ultrasound/shake combination washing.

  8. An Opportunistic Routing Mechanism Combined with Long-Term and Short-Term Metrics for WMN

    PubMed Central

    Piao, Xianglan; Qiu, Tie

    2014-01-01

    WMN (wireless mesh network) is a useful wireless multihop network with tremendous research value. The routing strategy decides the performance of network and the quality of transmission. A good routing algorithm will use the whole bandwidth of network and assure the quality of service of traffic. Since the routing metric ETX (expected transmission count) does not assure good quality of wireless links, to improve the routing performance, an opportunistic routing mechanism combined with long-term and short-term metrics for WMN based on OLSR (optimized link state routing) and ETX is proposed in this paper. This mechanism always chooses the highest throughput links to improve the performance of routing over WMN and then reduces the energy consumption of mesh routers. The simulations and analyses show that the opportunistic routing mechanism is better than the mechanism with the metric of ETX. PMID:25250379

  9. An opportunistic routing mechanism combined with long-term and short-term metrics for WMN.

    PubMed

    Sun, Weifeng; Wang, Haotian; Piao, Xianglan; Qiu, Tie

    2014-01-01

    WMN (wireless mesh network) is a useful wireless multihop network with tremendous research value. The routing strategy decides the performance of network and the quality of transmission. A good routing algorithm will use the whole bandwidth of network and assure the quality of service of traffic. Since the routing metric ETX (expected transmission count) does not assure good quality of wireless links, to improve the routing performance, an opportunistic routing mechanism combined with long-term and short-term metrics for WMN based on OLSR (optimized link state routing) and ETX is proposed in this paper. This mechanism always chooses the highest throughput links to improve the performance of routing over WMN and then reduces the energy consumption of mesh routers. The simulations and analyses show that the opportunistic routing mechanism is better than the mechanism with the metric of ETX.

  10. Combined optical and mechanical scanning in optical-resolution photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Li, Lei; Yeh, Chenghung; Hu, Song; Wang, Lidai; Soetikno, Brian T.; Chen, Ruimin; Zhou, Qifa; Shung, K. Kirk; Maslov, Konstantin I.; Wang, Lihong V.

    2014-03-01

    Combined optical and mechanical scanning (COMS) in optical-resolution photoacoustic microscopy (OR-PAM) has provided five scanning modes with fast imaging speed and wide field of view (FOV). With two-dimensional (2D) galvanometer-based optical scanning, we have achieved a 2 KHz B-scan rate and 50 Hz volumetric-scan rate, which enables real-time tracking of cell activities in vivo. With optical-mechanical hybrid 2D scanning, we are able to image a wide FOV (10×8 mm2) within 150 seconds, which is 20 times faster than the conventional mechanical scan in our second-generation OR-PAM. With three-dimensional mechanical-based contour scanning, we can maintain the optimal signal-to-noise ratio and spatial resolution of OR-PAM while imaging objects with uneven surfaces, which is ideal for fast and quantitative studies of tumors and the brain.

  11. Use of the GuideLiner catheter for aspiration thrombectomy in a patient with ST-elevation myocardial infarction with a large intracoronary thrombus.

    PubMed

    Numasawa, Yohei; Motoda, Hiroyuki; Yamazaki, Hiroyuki; Kuno, Toshiki; Kodaira, Masaki; Fujisawa, Taishi

    2016-04-01

    We report a 67-year-old man with ST-elevation myocardial infarction with a large intracoronary thrombus who was successfully treated with percutaneous thrombectomy using the GuideLiner catheter. This catheter is designed for the "Mother and Child" technique with a rapid exchange system and it has a larger internal diameter than conventional aspiration devices. When aspiration thrombectomy using a conventional aspiration catheter is not feasible or fails, use of the GuideLiner catheter for aspiration of thrombus is a reasonable alternative for primary percutaneous coronary intervention in patients with acute myocardial infarction.

  12. Contact Aspiration with the New ARC™ Catheter for Thrombectomy of Acute Ischemic Stroke: A Single Center Results.

    PubMed

    Gory, Benjamin; Turjman, Francis

    2017-10-05

    Contact aspiration has gained growing acceptance in the endovascular stroke therapy. The safety and efficacy data of the novel ARC™ catheter (Medtronic, Irvine, CA) used for intracranial thrombectomy was poorly evaluated. We reported our preliminary results with the ARC™ with regard to angiographic reperfusion, duration of thrombectomy, safety, and clinical outcome at 90 days. In a single center series including 20 large-vessel occlusion stroke patients prospectively collected, we retrospectively evaluated the safety and efficacy profiles of the ARC™ intracranial catheter for first-line contact aspiration. Successful reperfusion was defined as modified Thrombolysis in Cerebrovascular Infarction [mTICI] scores 2b-3 at final angiogram, and functional independence as modified Rankin Scale score 0 to 2 at 90 days. Median admission NIHSS was 15, and prior intravenous thrombolysis was administered in 12 patients (60%). Proximal occlusion was located in the anterior circulation in 16 patients (80%). Primary aspiration alone was successful in 10 out of 15 patients (67%) within a median time of 26 minutes. Overall successful reperfusion was achieved in 16 patients (80%) within a median time of 31 minutes. There were no device-related events. Median NIHSS was 2.5 at discharge. Six of 17 patients (35%) were independent, and 6 (35%) died at 90 days. Symptomatic intracerebral hemorrhage occurred in 5%. In our initial experience, the ARC™ appears safe and efficient for contact aspiration thrombectomy in large-vessel stroke therapy. However, improvement of its distal navigability needs further developments to improve the aspiration alone success, and large prospective studies are warranted. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Left Hand-assisted Laparoscopic Nephrectomy With Renal Vein Thrombectomy for Stage T3b Renal Cell Carcinoma.

    PubMed

    Ghareeb, George M; Kenleigh, Dorian A; Brown, James A

    2016-04-01

    A 60-year-old male was found to have an 8.0 cm left renal mass and associated renal vein thrombus on computed tomography. The thrombus extended 3 mm beyond the right aortic border to within 1.6 cm of the left border of the inferior vena cava. The patient underwent left nephrectomy with renal vein thrombectomy using a hand-assisted laparoscopic approach. The tumor thrombus was "milked" proximally back into left renal vein, which was then divided with an endovascular stapler. Left renal vein thrombi extending to right margin of the aorta can be managed with hand-assisted laparoscopic approach.

  14. Combining clinical studies and analogue experiments to investigate cognitive mechanisms in posttraumatic stress disorder

    PubMed Central

    Ehring, Thomas; Kleim, Birgit; Ehlers, Anke

    2013-01-01

    Research into cognitive mechanisms in posttraumatic stress disorder (PTSD) typically comprises two types of studies. The first group of studies is conducted with survivors of traumatic events and assesses the association between PTSD and cognitive variables with questionnaires and/or information processing paradigms. In the second group of studies, healthy non-traumatized individuals are exposed to an analogue stressor (e.g., a stressful film) and cognitive variables of interest are usually experimentally manipulated to investigate their effects on analogue PTSD symptoms. This review illustrates how studies of trauma survivors and analogue studies with non-traumatized populations can be usefully combined. Two examples for this approach are presented: (1) research into the role of perceptual priming for trauma-related stimuli and (2) research into trauma-related rumination. The advantages and limitations of both types of studies are discussed and it is argued that a combination of both approaches is needed to investigate cognitive mechanisms in PTSD. PMID:23814633

  15. Clinical experience with Angiojet: a comprehensive review.

    PubMed

    Ierardi, A M; Xhepa, G; Piffaretti, G; Bacuzzi, A; Tozzi, M; Carbone, M; Barile, A; Squillaci, E; Fonio, P; Brunese, L; Carrafiello, G

    2015-12-01

    The development of various sophisticated mechanical thrombectomy devices and the amassed experience of physicians in minimal invasive therapy produced a paradigm shift in vascular access management toward percutaneous declotting procedures, using pharmaceutical thrombolysis, mechanical thrombectomy, balloon thrombectomy, and a combination of the above techniques. In this setting, in the last years, AngioJet™ (Possis, Minneapolis, MN, USA) rheolytic thrombectomy (RT) showed an increasing use in emergency and election patients. The purpose of this review is to present the current status of percutaneous rheolytic thrombectomy in different fields of applications.

  16. A Hybrid Approach to Composite Damage and Failure Analysis Combining Synergistic Damage Mechanics and Peridynamics

    DTIC Science & Technology

    2017-03-30

    most manufacturing processes for polymer matrix composites (PMCs) one starts with dry bundles of fibers. On resin infusion, the initially closed-pack... Composite Damage and Failure Analysis Combining Synergistic Damage Mechanics and Peridynamics 5b. GRANT NUMBER NOOO 14-16-1-21 73 5c. PROGRAM...distributions. The activities related to Task 2 cover the new peridynamic model for multi-phase composites which can introduce the presence of pores and

  17. A Hybrid Approach to Composite Damage and Failure Analysis Combining Synergistic Damage Mechanics and Peridynamics

    DTIC Science & Technology

    2016-09-30

    during resin infusion in polymer matrix composites . Task 2.1 is concerned with damage evolution in a peridynamic model of poroelastic materials. Effects... Composite Damage and Failure Analysis Combining Synergistic Damage Mechanics and Peridynamics 5b. GRANT NUMBER NOOO 14-16-1-2173 5c. PROGRAM ELEMENT...element containing disordered fiber distributions. Procedures have been developed to simulate formation of fiber clusters during resin infusion in

  18. Combination therapy including serratiopeptidase improves outcomes of mechanical-antibiotic treatment of periimplantitis.

    PubMed

    Sannino, G; Gigola, P; Puttini, M; Pera, F; Passariello, C

    2013-01-01

    This study was designed as a retrospective analysis of clinical outcomes of cases of periimplantitis treated by mechanical debridement and the administration of antibiotics combined or not with the administration of either the proteolytic enzyme serratiopeptidase (SPEP) or non-steroidal anti-inflammatory drugs (NSAIDs). Clinical charts of 544 partially edentulous patients treated for periimplantitis between June 1996 and December 2010 were analyzed to obtain clinical data of the affected implants just before the beginning of treatment and 12 months later to evaluate the outcomes of combined mechanical antibiotic treatment alone or in combination with the co-administration of the anti-inflammatory SPEP or NSAIDs. The comparative analysis revealed that therapeutic outcomes were significantly different in the three groups. Failure rate in the group that received SPEP (6 percent) was significantly lower compared to the group that received NSAIDS (16.9 percent; P less than 0.01) and to the group that received no anti-inflammatory therapy (18.9 percent; P less than 0.01). Treatment including SPEP was associated with significantly better healing also when successful treatments alone were considered. The data reported in this paper strongly support the hypothesis that SPEP is a valid addition to protocols for the combined therapy of peri-implantitis. In fact, it allows to enhance success rates significantly and also favors better tissue repair around successfully treated implants as compared to other regimens.

  19. Characterization of PV modules by combining results of mechanical and electrical analysis methods

    NASA Astrophysics Data System (ADS)

    Sander, Martin; Henke, Bastian; Schwarz, Hannes; Dietrich, Sascha; Schweizer, Stefan; Ebert, Matthias; Bagdahn, Jörg

    2010-08-01

    Photovoltaic modules (PV modules) are supposed to have a lifetime of more than 20 years under various environmental conditions like temperature changes, mechanical loads, etc. Common outdoor exposure may influence efficiency and lifetime which necessitates assessment of PV module performance and detection of output deficits. For this purpose reliable and nondestructive testing methods are desirable. Commercially available PV modules were tested by different analysis methods. The PV module's electrical properties were investigated by thermography and electroluminescence measurements. The combination of these two techniques is well-suited to detect many cell and module defects. A crystalline module showed significant cell breakage after temperature cycle test. To observe the mechanisms of this specific defect type laminated test specimens on smaller scales were produced and analyzed over production process and during temperature cycles derived from the international standards IEC 61215 and IEC 61646. The defect study on small scales allows conclusions about the defect's influence on larger PV modules. Further methods capable for mechanical characterization like Laser Doppler vibrometry, surface geometry scan and digital image correlation are presented briefly. The combination of the methods mentioned above allows a very precise assessment of the mechanical and electrical capability which is essential for reliability and lifetime concepts.

  20. Measuring the mechanical properties of plant cells by combining micro-indentation with osmotic treatments.

    PubMed

    Weber, Alain; Braybrook, Siobhan; Huflejt, Michal; Mosca, Gabriella; Routier-Kierzkowska, Anne-Lise; Smith, Richard S

    2015-06-01

    Growth in plants results from the interaction between genetic and signalling networks and the mechanical properties of cells and tissues. There has been a recent resurgence in research directed at understanding the mechanical aspects of growth, and their feedback on genetic regulation. This has been driven in part by the development of new micro-indentation techniques to measure the mechanical properties of plant cells in vivo. However, the interpretation of indentation experiments remains a challenge, since the force measures results from a combination of turgor pressure, cell wall stiffness, and cell and indenter geometry. In order to interpret the measurements, an accurate mechanical model of the experiment is required. Here, we used a plant cell system with a simple geometry, Nicotiana tabacum Bright Yellow-2 (BY-2) cells, to examine the sensitivity of micro-indentation to a variety of mechanical and experimental parameters. Using a finite-element mechanical model, we found that, for indentations of a few microns on turgid cells, the measurements were mostly sensitive to turgor pressure and the radius of the cell, and not to the exact indenter shape or elastic properties of the cell wall. By complementing indentation experiments with osmotic experiments to measure the elastic strain in turgid cells, we could fit the model to both turgor pressure and cell wall elasticity. This allowed us to interpret apparent stiffness values in terms of meaningful physical parameters that are relevant for morphogenesis.

  1. Combined Quantum Mechanical and Molecular Mechanics Studies of the Electron-Transfer Reactions Involving Carbon Tetrachloride in Solution

    SciTech Connect

    Valiev, Marat; Bylaska, Eric J.; Dupuis, Michel; Tratnyek, Paul G.

    2008-03-27

    The reductive dechlorination of carbon tetrachloride, CC₄, was investigated using combined high level quantum mechanical and molecular mechanics (QM/MM) approach. The first electron transfer process was assumed to proceed by a concerted electron transfer-bond breaking mechanism, and reaction barriers for the first electron reduction were estimated by using the crossing point of the free energy profiles of CCl₃-Cl and CCl₃-Cl•- as a function of the CCl₃-Cl distance. The results of these calculations showed that the activation barriers for this reaction are reachable under a wide range of reduction potentials. In the gas-phase, the barrier to reduction varied from 0.8 kcal/mol for reducing agent with a -5 kcal/mol work function to 24.7 kcal/mol for a reducing agent with a 40 kcal/mol work function at the CCSD(T)/aug-cc-pVDZ level. In the aqueous phase, QM/MM calculations at the CCSD(T)/aug-cc-pVDZ level predicted that the barrier to reduction varied from 0.7 kcal/mol to 35.2 kcal/mol for -2.32 V and 0.93 V reduction potentials respectively. COSMO continuum solvation calculations were also performed for comparison. For strong reducing agents (EH < -1.5V) very little difference was seen between the QM/MM and COSMO activation barriers. For weak reducing agents (EH > 0V) the activation barriers differed by as much as 6 kcal/mol between the QM/MM and COSMO calculations. These results demonstrate that ab initio electronic structure methods coupled with explicit molecular mechanics representation of the aqueous environment offer an efficient and accurate way to calculate the free energy reaction barriers for dissociative electron transfer reactions of organochlorine compounds to identify the potentially important environmental degradation processes.

  2. Mechanism of Sporicidal Activity for the Synergistic Combination of Peracetic Acid and Hydrogen Peroxide.

    PubMed

    Leggett, Mark J; Schwarz, J Spencer; Burke, Peter A; McDonnell, Gerald; Denyer, Stephen P; Maillard, Jean-Yves

    2015-12-04

    There is still great interest in controlling bacterial endospores. The use of chemical disinfectants and, notably, oxidizing agents to sterilize medical devices is increasing. With this in mind, hydrogen peroxide (H2O2) and peracetic acid (PAA) have been used in combination, but until now there has been no explanation for the observed increase in sporicidal activity. This study provides information on the mechanism of synergistic interaction of PAA and H2O2 against bacterial spores. We performed investigations of the efficacies of different combinations, including pretreatments with the two oxidizers, against wild-type spores and a range of spore mutants deficient in the spore coat or small acid-soluble spore proteins. The concentrations of the two biocides were also measured in the reaction vessels, enabling the assessment of any shift from H2O2 to PAA formation. This study confirmed the synergistic activity of the combination of H2O2 and PAA. However, we observed that the sporicidal activity of the combination is largely due to PAA and not H2O2. Furthermore, we observed that the synergistic combination was based on H2O2 compromising the spore coat, which was the main spore resistance factor, likely allowing better penetration of PAA and resulting in the increased sporicidal activity.

  3. Mechanism of Sporicidal Activity for the Synergistic Combination of Peracetic Acid and Hydrogen Peroxide

    PubMed Central

    Leggett, Mark J.; Schwarz, J. Spencer; Burke, Peter A.; McDonnell, Gerald; Denyer, Stephen P.

    2015-01-01

    There is still great interest in controlling bacterial endospores. The use of chemical disinfectants and, notably, oxidizing agents to sterilize medical devices is increasing. With this in mind, hydrogen peroxide (H2O2) and peracetic acid (PAA) have been used in combination, but until now there has been no explanation for the observed increase in sporicidal activity. This study provides information on the mechanism of synergistic interaction of PAA and H2O2 against bacterial spores. We performed investigations of the efficacies of different combinations, including pretreatments with the two oxidizers, against wild-type spores and a range of spore mutants deficient in the spore coat or small acid-soluble spore proteins. The concentrations of the two biocides were also measured in the reaction vessels, enabling the assessment of any shift from H2O2 to PAA formation. This study confirmed the synergistic activity of the combination of H2O2 and PAA. However, we observed that the sporicidal activity of the combination is largely due to PAA and not H2O2. Furthermore, we observed that the synergistic combination was based on H2O2 compromising the spore coat, which was the main spore resistance factor, likely allowing better penetration of PAA and resulting in the increased sporicidal activity. PMID:26637595

  4. [Mechanism reversing MDR of K562/A02 by garlicin combined with erythromycin].

    PubMed

    Yu, Min; Liu, Xin; Xu, Bo; Wang, Hui; Chen, Wei

    2008-10-01

    This study was purposed to investigate the reversal effect of garlicin, erythromycin alone or combination of garlicin with erythromycin on K562/A02 and its possible mechanisms, so as to provide experimental evidence for combination reversal strategies. Cytotoxicity and the reversal effect of garlicin and erythromycin alone and combination of this two drugs were detected by MTT assay. The expression of mdr1 gene of K562/A02 was detected by RT-PCR. The P-gp expression was observed by immunohistochemical technique. Flow cytometry was used to detect intracellular drug concentration. The results showed that the sensitivity of K562/A02 to ADM increased somewhat in the presence of 1, 4, 8 mg/L garlicin, the reversal multiples at 1, 4, 8 mg/L garlicin were 1.80, 2.26 and 2.82 respectively in dose-dependent manner. The reversal multiple of erythromycin 60 mg/L was 2.20. The combination of two drugs could increase the reversal multiple to 4.94, and had no more cytotoxin. Both of garlicin and erythromycin alone could down-regulate the expression of mdr1 and P-gp of K562/A02 and elevate the intracellular concentrations of ADM in K562/A02 cells. Meanwhile, the effects described above were enhanced when garlicin was combined with erythromycin. It is concluded that the garlicin and erythromycin alone under cytotoxic dose both can reverse the MDR of K562/A02 cells effectively. Moreover, the combination of two drugs is more effective than that in use alone. Combination of these two drugs shows synergistic actions in regulating the expression of mdr1/P-gp and increasing the intracellular concentrations of ADM in K562/A02 cell.

  5. COMBINE*: An integrated opto-mechanical tool for laser performance modeling

    NASA Astrophysics Data System (ADS)

    Rehak, M.; Di Nicola, J. M.

    2015-02-01

    Accurate modeling of thermal, mechanical and optical processes is important for achieving reliable, high-performance high energy lasers such as those at the National Ignition Facility [1] (NIF). The need for this capability is even more critical for high average power, high repetition rate applications. Modeling the effects of stresses and temperature fields on optical properties allows for optimal design of optical components and more generally of the architecture of the laser system itself. Stresses change the indices of refractions and induce inhomogeneities and anisotropy. We present a modern, integrated analysis tool that efficiently produces reliable results that are used in our laser propagation tools such as VBL [5]. COMBINE is built on and supplants the existing legacy tools developed for the previous generations of lasers at LLNL but also uses commercially available mechanical finite element codes ANSYS or COMSOL (including computational fluid dynamics). The COMBINE code computes birefringence and wave front distortions due to mechanical stresses on lenses and slabs of arbitrary geometry. The stresses calculated typically originate from mounting support, vacuum load, gravity, heat absorption and/or attending cooling. Of particular importance are the depolarization and detuning effects of nonlinear crystals due to thermal loading. Results are given in the form of Jones matrices, depolarization maps and wave front distributions. An incremental evaluation of Jones matrices and ray propagation in a 3D mesh with a stress and temperature field is performed. Wavefront and depolarization maps are available at the optical aperture and at slices within the optical element. The suite is validated, user friendly, supported, documented and amenable to collaborative development. * COMBINE stands for Code for Opto-Mechanical Birefringence Integrated Numerical Evaluations.

  6. The concentric-ring array for ultrasound hyperthermia: combined mechanical and electrical scanning.

    PubMed

    Ibbini, M S; Cain, C A

    1990-01-01

    While two-dimensional phased arrays can be electronically focused and steered in three dimensions without physically moving the applicator, they generally require a relatively large number of small transducer elements and, consequently, complex drive electronics. A configuration that does not require a large number of elements is that of a concentric-ring array. The field conjugation method can be used to produce a focal spot (or multiple spots) along the array axis. The resulting focal regions are very small and need to be steered transversely to heat tumours of typical size. However, steering the focused beam away from the array axis results in annular heating patterns which are often associated with undesired secondary foci (hot spots). In this paper, a method based on combining electrical and mechanical scanning using a concentric-ring applicator is presented. Advantages of the new method over the mechanically scanned fixed-focus transducers, currently in use, are pointed out. Computer simulations are conducted to investigate the possibility of heating different size tumours by appropriately combining the two scanning techniques. The bioheat transfer equation is solved numerically and temperature distributions associated with relevant heating patterns are presented and discussed. The simulations demonstrate the possibility of the combined technique to produce useful heating patterns which cannot be produced by either technique separately.

  7. Restrained Proton Indicator in Combined Quantum-Mechanics/Molecular-Mechanics Dynamics Simulations of Proton Transfer through a Carbon Nanotube.

    PubMed

    Duster, Adam W; Lin, Hai

    2017-09-14

    Recently, a collective variable "proton indicator" was purposed for tracking an excess proton solvated in bulk water in molecular dynamics simulations. In this work, we demonstrate the feasibility of utilizing the position of this proton indicator as a reaction coordinate to model an excess proton migrating through a hydrophobic carbon nanotube in combined quantum-mechanics/molecular-mechanics simulations. Our results indicate that applying a harmonic restraint to the proton indicator in the bulk solvent near the nanotube pore entrance leads to the recruitment of water molecules into the pore. This is consistent with an earlier study that employed a multistate empirical valence bond potential and a different representation (center of excess charge) of the proton. We attribute this water recruitment to the delocalized nature of the solvated proton, which prefers to be in high-dielectric bulk solvent. While water recruitment into the pore is considered an artifact in the present simulations (because of the artificially imposed restraint on the proton), if the proton were naturally restrained, it could assist in building water wires prior to proton transfer through the pore. The potential of mean force for a proton translocation through the water-filled pore was computed by umbrella sampling, where the bias potentials were applied to the proton indicator. The free energy curve and barrier heights agree reasonably with those in the literature. The results suggest that the proton indicator can be used as a reaction coordinate in simulations of proton transport in confined environments.

  8. Understanding CO2 capture mechanisms in aqueous hydrazine via combined NMR and first-principles studies.

    PubMed

    Lee, Byeongno; Stowe, Haley M; Lee, Kyu Hyung; Hur, Nam Hwi; Hwang, Son-Jong; Paek, Eunsu; Hwang, Gyeong S

    2017-09-13

    Aqueous amines are currently the most promising solution for large-scale CO2 capture from industrial sources. However, molecular design and optimization of amine-based solvents have proceeded slowly due to a lack of understanding of the underlying reaction mechanisms. Unique and unexpected reaction mechanisms involved in CO2 absorption into aqueous hydrazine are identified using (1)H, (13)C, and (15)N NMR spectroscopy combined with first-principles quantum-mechanical simulations. We find production of both hydrazine mono-carbamate (NH2-NH-COO(-)) and hydrazine di-carbamate ((-)OOC-NH-NH-COO(-)), with the latter becoming more populated with increasing CO2 loading. Exchange NMR spectroscopy also demonstrates that the reaction products are in dynamic equilibrium under ambient conditions due to CO2 exchange between mono-carbamate and di-carbamate as well as fast proton transfer between un-protonated free hydrazine and mono-carbamate. The exchange rate rises steeply at high CO2 loadings, enhancing CO2 release, which appears to be a unique property of hydrazine in aqueous solution. The underlying mechanisms of these processes are further evaluated using quantum mechanical calculations. We also analyze and discuss reversible precipitation of carbamate and conversion of bicarbonate to carbamates. The comprehensive mechanistic study provides useful guidance for optimal design of amine-based solvents and processes to reduce the cost of carbon capture. Moreover, this work demonstrates the value of a combined experimental and computational approach for exploring the complex reaction dynamics of CO2 in aqueous amines.

  9. Clinic Predictive Factors for Insufficient Myocardial Reperfusion in ST-Segment Elevation Myocardial Infarction Patients Treated with Selective Aspiration Thrombectomy during Primary Percutaneous Coronary Intervention.

    PubMed

    Tian, Jinfan; Liu, Yue; Song, Xiantao; Zhang, Min; Xu, Feng; Yuan, Fei; Lyu, Shuzheng

    2016-01-01

    Background. Insufficient data are available on the potential benefit of selective aspiration and clinical predictors for no-reflow in STEMI patients undergoing primary percutaneous coronary intervention (PPCI) adjunct with aspiration thrombectomy. Objective. The aim of our study was to investigate clinical predictors for insufficient reperfusion in patients with high thrombus burden treated with PPCI and manual aspiration thrombectomy. Methods. From January 2011 till December 2015, 277 STEMI patients undergoing manual aspiration thrombectomy and PPCI were selected and 202 patients with a Thrombolysis in Myocardial Infarction (TIMI) thrombus grade 4~5 were eventually involved in our study. According to a cTFC value, patients were divided into Group I (cTFC > 40), namely, insufficient reperfusion group; Group II (cTFC ≤ 40), namely, sufficient reperfusion group. Results. Univariate analysis showed that hypertension, multivessel disease, time from symptom to PCI (≧4.8 hours), and postaspiration cTFC > 40 were negative predictors for insufficient reperfusion. After multivariate adjustment, age ≧ 60 years, hypertension, time from symptom to PCI (≧4.8 hours), and postaspiration cTFC > 40 were independently associated with insufficient reperfusion in STEMI patients treated with manual aspiration thrombectomy. Upfront intracoronary GP IIb/IIIa inhibitor (Tirofiban) was positively associated with improved myocardial reperfusion. Conclusion. Fully identifying risk factors will help to improve the effectiveness of selective thrombus aspiration.

  10. Clinic Predictive Factors for Insufficient Myocardial Reperfusion in ST-Segment Elevation Myocardial Infarction Patients Treated with Selective Aspiration Thrombectomy during Primary Percutaneous Coronary Intervention

    PubMed Central

    Song, Xiantao; Zhang, Min; Xu, Feng; Yuan, Fei

    2016-01-01

    Background. Insufficient data are available on the potential benefit of selective aspiration and clinical predictors for no-reflow in STEMI patients undergoing primary percutaneous coronary intervention (PPCI) adjunct with aspiration thrombectomy. Objective. The aim of our study was to investigate clinical predictors for insufficient reperfusion in patients with high thrombus burden treated with PPCI and manual aspiration thrombectomy. Methods. From January 2011 till December 2015, 277 STEMI patients undergoing manual aspiration thrombectomy and PPCI were selected and 202 patients with a Thrombolysis in Myocardial Infarction (TIMI) thrombus grade 4~5 were eventually involved in our study. According to a cTFC value, patients were divided into Group I (cTFC > 40), namely, insufficient reperfusion group; Group II (cTFC ≤ 40), namely, sufficient reperfusion group. Results. Univariate analysis showed that hypertension, multivessel disease, time from symptom to PCI (≧4.8 hours), and postaspiration cTFC > 40 were negative predictors for insufficient reperfusion. After multivariate adjustment, age ≧ 60 years, hypertension, time from symptom to PCI (≧4.8 hours), and postaspiration cTFC > 40 were independently associated with insufficient reperfusion in STEMI patients treated with manual aspiration thrombectomy. Upfront intracoronary GP IIb/IIIa inhibitor (Tirofiban) was positively associated with improved myocardial reperfusion. Conclusion. Fully identifying risk factors will help to improve the effectiveness of selective thrombus aspiration. PMID:27891513

  11. Endovascular Treatment of a Ruptured Profunda Femoral Artery Branch After Fogarty Thrombectomy of a Femoro-Femoral Crossover Arterial Graft: A Case Report and Review of the Literature

    SciTech Connect

    Manousaki, Eirini; Tsetis, Dimitrios; Kostas, Theodoros; Katsamouris, Asterios

    2010-02-15

    We present a very rare case of a life-threatening rupture of a profunda femoral artery distal branch after a Fogarty thrombectomy of a thrombosed crossover synthetic graft between the ipsilateral common femoral artery and a contralateral iliac-popliteal graft; the bleeding profunda femoral artery branch was successfully embolized with metallic coils through the axillary artery approach.

  12. Biodiesel production from palm oil using combined mechanical stirred and ultrasonic reactor.

    PubMed

    Choedkiatsakul, I; Ngaosuwan, K; Cravotto, G; Assabumrungrat, S

    2014-07-01

    This paper investigates the production of biodiesel from palm oil using a combined mechanical stirred and ultrasonic reactor (MS-US). The incorporation of mechanical stirring into the ultrasonic reactor explored the further improvement the transesterification of palm oil. Initial reaction rate values were 54.1, 142.9 and 164.2 mmol/L min for the mechanical-stirred (MS), ultrasonic (US) and MS-US reactors, respectively. Suitable methanol to oil molar ratio and the catalyst loading values were found to be 6 and 1 of oil, respectively. The effect of ultrasonic operating parameters; i.e. frequency, location, and number of transducer, has been investigated. Based on the conversion yield at the reactor outlet after 1 h, the number of transducers showed a relevant role in the reaction rate. Frequency and transducer location would appear to have no significant effect. The properties of the obtained biodiesel (density, viscosity, pour point, and flash point) satisfy the ASTM standard. The combined MS-US reactors improved the reaction rate affording the methyl esters in higher yield.

  13. Mechanism-based drug combinations with the DNA-strand-breaking nucleoside analog, CNDAC

    PubMed Central

    Liu, Xiaojun; Jiang, Yingjun; Nowak, Billie; Hargis, Sarah; Plunkett, William

    2016-01-01

    CNDAC (2’-C-cyano-2’-deoxy-1-β-D-arabino-pentofuranosyl-cytosine, DFP10917) and its orally bioavailable prodrug, sapacitabine, are undergoing clinical trials for hematological malignancies and solid tumors. The unique action mechanism of inducing DNA strand breaks distinguishes CNDAC from other deoxycytidine analogs. To optimize the clinical potentials of CNDAC, we explored multiple strategies combining CNDAC with chemotherapeutic agents targeting distinct DNA damage repair pathways that are currently in clinical use. The ability of each agent to decrease proliferative potential, determined by clonogenic assays, was determined in paired cell lines proficient and deficient in certain DNA repair proteins. Subsequently each agent was used in combination with CNDAC at fixed concentration ratios. The clonogenicity was quantitated by median effect analysis, and a combination index was calculated. The c-Abl kinase inhibitor, imatinib, had synergy with CNDAC in HCT116 cells, regardless of p53 status. Inhibitors of PARP1 that interfere with homologous recombination (HR) repair or base excision repair (BER) and agents such as temozolomide that cause DNA damage repaired by the BER pathway were also synergistic with CNDAC. The toxicity of the nitrogen mustards, bendamustine and cytoxan, or of platinum compounds, which generate DNA adducts repaired by nucleotide excision repair and HR, was additive with CNDAC. An additive cell killing was also achieved by the combination of CNDAC with taxane mitotic inhibitors (paclitaxel and docetaxel). At concentrations which allow survival of the majority of wild type cells, the synergistic or additive combination effects were selective in HR-deficient cells. This study provides mechanistic rationales for combining CNDAC with other active drugs. PMID:27474148

  14. Mechanisms for optimising photodynamic therapy: second-generation photosensitisers in combination with mitomycin C.

    PubMed Central

    van Geel, I. P.; Oppelaar, H.; Oussoren, Y. G.; Schuitmaker, J. J.; Stewart, F. A.

    1995-01-01

    Mechanisms for improving photodynamic therapy (PDT) were investigated in the murine RIF1 tumour using meso-tetrahydroxyphenylchlorin (m-THPC) or bacteriochlorin a (BCA) as photosensitisers and comparing these results with Photofrin-mediated PDT. The 86Rb extraction technique was used to measure changes in perfusion at various times after interstitial PDT. Non-curative combinations of light doses with m-THPC and BCA PDT markedly decreased vascular perfusion. This decrease was more pronounced for both new photosensitisers than for Photofrin. Comparison of tumour perfusion after PDT with tumour response revealed an inverse correlation for all three photosensitisers, but the relationship was less clear for m-THPC and BCA. In vivo/in vitro experiments were performed after Photofrin or m-THPC PDT in order to assess direct tumour kill (immediate plating) vs indirect vascular effects (delayed plating). For both photosensitisers, there was little direct cell killing but clonogenic survival decreased as the interval between treatment and excision increased. When m-THPC PDT was combined with mitomycin C (MMC), light doses could be decreased by a factor of 2 for equal tumour effects. Lower light and m-THPC doses could be used compared with Photofrin PDT in combination with MMC. BCA PDT with MMC did not result in a greater tumour response compared with BCA PDT alone. Reduction in both light and photosensitiser does for effective PDT regimes in combination with MMC offers substantial clinical advantages, since both treatment time and skin photosensitisation will be reduced. PMID:7640216

  15. Synergistic Effects and Mechanisms of Budesonide in Combination with Fluconazole against Resistant Candida albicans

    PubMed Central

    Li, Xiuyun; Yu, Cuixiang; Huang, Xin; Sun, Shujuan

    2016-01-01

    Candida albicans is an important opportunistic pathogen, causing both superficial mucosal infections and life-threatening systemic diseases in the clinic. The emergence of drug resistance in Candida albicans has become a noteworthy phenomenon due to the extensive use of antifungal agents and the development of biofilms. This study showed that budesonide potentiates the antifungal effect of fluconazole against fluconazole-resistant Candida albicans strains both in vitro and in vivo. In addition, our results demonstrated, for the first time, that the combination of fluconazole and budesonide can reverse the resistance of Candida albicans by inhibiting the function of drug transporters, reducing the formation of biofilms, promoting apoptosis and inhibiting the activity of extracellular phospholipases. This is the first study implicating the effects and mechanisms of budesonide against Candida albicans alone or in combination with fluconazole, which may ultimately lead to the identification of new potential antifungal targets. PMID:28006028

  16. Quantifying Subpopulation Synergy for Antibiotic Combinations via Mechanism-Based Modeling and a Sequential Dosing Design

    PubMed Central

    Ly, Neang S.; Xu, Hongmei; Tsuji, Brian T.

    2013-01-01

    Quantitative modeling of combination therapy can describe the effects of each antibiotic against multiple bacterial populations. Our aim was to develop an efficient experimental and modeling strategy that evaluates different synergy mechanisms using a rapidly killing peptide antibiotic (nisin) combined with amikacin or linezolid as probe drugs. Serial viable counts over 48 h were obtained in time-kill experiments with all three antibiotics in monotherapy against a methicillin-resistant Staphylococcus aureus USA300 strain (inoculum, 108 CFU/ml). A sequential design (initial dosing of 8 or 32 mg/liter nisin, switched to amikacin or linezolid at 1.5 h) assessed the rate of killing by amikacin and linezolid against nisin-intermediate and nisin-resistant populations. Simultaneous combinations were additionally studied and all viable count profiles comodeled in S-ADAPT and NONMEM. A mechanism-based model with six populations (three for nisin times two for amikacin) yielded unbiased and precise (r = 0.99, slope = 1.00; S-ADAPT) individual fits. The second-order killing rate constants for nisin against the three populations were 5.67, 0.0664, and 0.00691 liter/(mg · h). For amikacin, the maximum killing rate constants were 10.1 h−1 against its susceptible and 0.771 h−1 against its less-susceptible populations, with 14.7 mg/liter amikacin causing half-maximal killing. After incorporating the effects of nisin and amikacin against each population, no additional synergy function was needed. Linezolid inhibited successful bacterial replication but did not efficiently kill populations less susceptible to nisin. Nisin plus amikacin achieved subpopulation synergy. The proposed sequential and simultaneous dosing design offers an efficient approach to quantitatively characterize antibiotic synergy over time and prospectively evaluate antibiotic combination dosing strategies. PMID:23478962

  17. Effect of Physical Aging on Mechanical Behavior of an Elastomeric Glass under Combined Pressure and Temperature.

    DTIC Science & Technology

    1986-12-01

    NO. 3. RECIPIENT’S CATALOG NUMBER Technical Report No. 7 C.- 4. TITLE (and Subtitle) S . TYPE OF REPORT & PERIOD COVERED Effect of Physical Aging on...Mechanical Behavior of an Elastomeric Glass Under Combined Pressure and Temperature G. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(e) S . CONTRACT OR GRANT...NUMBER( s ) K. Vijayan and K. D. Pae NOOO14-82-K-0608 9. PERFORMING r" GANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK High PrE 3,ure

  18. Structural Stability of a Stiffened Aluminum Fuselage Panel Subjected to Combined Mechanical and Internal Pressure Loads

    NASA Technical Reports Server (NTRS)

    Rouse, Marshall; Young, Richard D.; Gehrki, Ralph R.

    2003-01-01

    Results from an experimental and analytical study of a curved stiffened aluminum panel subjected to combined mechanical and internal pressure loads are presented. The panel loading conditions were simulated using a D-box test fixture. Analytical buckling load results calculated from a finite element analysis are presented and compared to experimental results. Buckling results presented indicate that the buckling load of the fuselage panel is significantly influenced by internal pressure loading. The experimental results suggest that the stress distribution is uniform in the panel prior to buckling. Nonlinear finite element analysis results correlates well with experimental results up to buckling.

  19. Creep behavior of magnetorheological elastomers under combined magnetic and mechanical loads

    NASA Astrophysics Data System (ADS)

    Ghafoorianfar, Nima

    2016-04-01

    In this work, creep behavior of magnetorheological elastomers is investigated under combined magnetic and mechanical loading conditions. For the first time, a creep behavior model of MR elastomer is presented in this work in compression mode. A Weibull distribution function is used to model this behavior of MRE very well for both magnetic and mechanical loading conditions. This new model, which have been used previously for modeling recovery of thermosetting polymeric materials, is able to demonstrate the MRE creep behavior more accurately compared to previous models in the literature. The results show that the creep intensity is highly dependent on the carbonyl iron particle volume percentage of MRE samples, as well as the applied magnetic field.

  20. Surfaces with combined microscale and nanoscale structures: a route to mechanically stable superhydrophobic surfaces?

    PubMed

    Groten, Jonas; Rühe, Jürgen

    2013-03-19

    Materials with superhydrophobic properties are usually generated by covering the surfaces with hydrophobic nanoscale rough features. A major problem, however, for any practical application of such strongly water-repellent surfaces is the mechanical fragility of the nanostructures. Even moderate forces caused by touching or rubbing the surfaces are frequently strong enough to destroy the nanostructures and lead to the loss of the superhydrophobic properties. In this article, we study the mechanical stability of superhydrophobic surfaces with three different topographies: nano- and microscale features and surfaces carrying a combination of both. The surfaces are generated by silicon etching and subsequent coating with a monolayer of a fluoropolymer (PFA). We perform controlled wear tests on the different surfaces and discuss the impact of wear on the wetting properties of the different surfaces.

  1. Endovascular Treatment of Phlegmasia Cerulea Dolens with Impending Venous Gangrene: Manual Aspiration Thrombectomy as the First-Line Thrombus Removal Method

    SciTech Connect

    Oguzkurt, Levent Ozkan, Ugur; Demirturk, Orhan S.; Gur, Serkan

    2011-12-15

    Purpose: Our purpose was to report the outcome of endovascular treatment with manual aspiration thrombectomy as the first-line thromboablative method for phlegmasia cerulea dolens. Methods: Between October 2006 and May 2010, seven consecutive patients (5 women, 2 men; age range, 31-80 years) with the diagnosis of phlegmasia cerulea dolens secondary to acute iliofemoral deep venous thrombosis had endovascular treatment with manual aspiration thrombectomy. Catheter-directed thrombolysis and stent placement were used as adjunctive procedures. Phlegmasia was left-sided in five and right-sided in two patients. Results: All patients had associated great saphenous vein thrombosis in addition to iliofemoral deep vein thrombosis (DVT). Aspiration thrombectomy completely removed the thrombus from the popliteal vein to the inferior vena cava (IVC) in all cases. Three patients with May-Thurner syndrome had stent placement in the left common iliac vein. Two patients had early recurrences. Repeated aspiration thrombectomy was unsuccessful in one patient. There were no complications related to the procedure. One patient who had been successfully treated died of sepsis and another patient who had unsuccessful repeated interventions had below-the-knee amputation. Overall, the clinical success and survival rates of patients in this study were 86%. On follow-up, three patients with successful treatment were asymptomatic with no deep venous insufficiency. One of these patients died during the 4-month follow-up period. Two patients had mild ankle swelling with deep venous insufficiency. Conclusions: Manual aspiration thrombectomy with adjunctive use of catheter-directed thrombolysis and stent placement is an effective endovascular treatment method with high clinical success and survival rates for phlegmasia cerulean dolens.

  2. Design and fabrication of miniaturized PEM fuel cell combined microreactor with self-regulated hydrogen mechanism

    NASA Astrophysics Data System (ADS)

    Balakrishnan, A.; Frei, M.; Kerzenmacher, S.; Reinecke, H.; Mueller, C.

    2015-12-01

    In this work we present the design and fabrication of the miniaturized PEM fuel cell combined microreactor system with hydrogen regulation mechanism and testing of prototype microreactor. The system consists of two components (i) fuel cell component and (ii) microreactor component. The fuel cell component represents the miniaturized PEM fuel cell system (combination of screen printed fuel cell assembly and an on-board hydrogen storage medium). Hydrogen production based on catalytic hydrolysis of chemical hydride takes place in the microreactor component. The self-regulated hydrogen mechanism based on the gaseous hydrogen produced from the catalytic hydrolysis of sodium borohydride (NaBH4) gets accumulated as bubbles at the vicinity of the hydrophobic coated hydrogen exhaust holes. When the built up hydrogen bubbles pressure exceeds the burst pressure at the hydrogen exhaust holes the bubble collapses. This collapse causes a surge of fresh NaBH4 solution onto the catalyst surface leading to the removal of the reaction by-products formed at the active sites of the catalyst. The catalyst used in the system is platinum deposited on a base substrate. Nickel foam, carbon porous medium (CPM) and ceramic plate were selected as candidates for base substrate for developing a robust catalyst surface. For the first time the platinum layer fabricated by pulsed electrodeposition and dealloying (EPDD) technique is used for hydrolysis of NaBH4. The major advantages of such platinum catalyst layers are its high surface area and their mechanical stability. Prototype microreactor system with self-regulated hydrogen mechanism is demonstrated.

  3. Combined nutritional support in patients with chronic obstructive pulmonary disease (COPD), under mechanical ventilation (MV).

    PubMed

    Grigorakos, Leonidas; Sotiriou, Evangelia; Markou, Nikolaos; Stratouli, Stamatina; Boutzouka, Eleni; Philntisis, George; Baltopoulos, George

    2009-01-01

    The importance of nutrition is clearly established in the management of the critically ill patient: malnutrition contributes to immune incompetence, poor wound healing, increased postoperative complication and prolonged hospital stay. The interaction between nutritional status, nutritional supply and respiratory function is important in the management of the Chronic Obstructive pulmonary Disease (COPD) patients under mechanical ventilation (MV). In the present study was analyzed the benefits of combined nutritional support in patients with COPD under MV. One hundred ninety two (192) patients with COPD were admitted to our Intensive Care Unit (ICU), due to severe respiratory failure of whom 163 (84.9%) patients were under MV. In 18 (11.04%) patients after the 10th day under MV and due to severe malnutrition (serum albumin < 2.5 gm/dl, total lymphocyte count (TLC) < 900/mm3), added in the enteral nutrition (EN) of 1800 Kcals and parenteral nutrition (PN) of 2000 Kcals, at high concentration in lipids from central venous catheter. Seven (38.89%) patients on the 4th day, after combined nutrition, had a positive balance of nitrogen and normal level of the nutritional indices, 4 (22.22%) were on normal level on the 5th day, 3 (16.67%) on the 6th day, 1 (5.56%) on the 7th day after combined nutrition. We had no complications from the combination of EN and PN. Conclusively, of these 18 patients that were given both EN and PN, 15 (83.33%) were weaned from MV and continued the combined nutritional support for 3 days, while 3 (16.67%) died during the combination of EN and PN, without having achieved a normal level of the indices of nutrition and without a positive balance of nitrogen. In this study was found that: 1. patients with COPD under MV rapidly developed malnutrition, 2. the combination EN and PN without complications contribute to the weaning from MV, 3. positive nitrogen balance and normal increases of nutrition are achieved after the 4th day of combined nutrition

  4. Probabilistic Simulation of Combined Thermo-Mechanical Cyclic Fatigue in Composites

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    2011-01-01

    A methodology to compute probabilistically-combined thermo-mechanical fatigue life of polymer matrix laminated composites has been developed and is demonstrated. Matrix degradation effects caused by long-term environmental exposure and mechanical/thermal cyclic loads are accounted for in the simulation process. A unified time-temperature-stress-dependent multifactor-interaction relationship developed at NASA Glenn Research Center has been used to model the degradation/aging of material properties due to cyclic loads. The fast probability-integration method is used to compute probabilistic distribution of response. Sensitivities of fatigue life reliability to uncertainties in the primitive random variables (e.g., constituent properties, fiber volume ratio, void volume ratio, ply thickness, etc.) computed and their significance in the reliability-based design for maximum life is discussed. The effect of variation in the thermal cyclic loads on the fatigue reliability for a (0/+/-45/90)s graphite/epoxy laminate with a ply thickness of 0.127 mm, with respect to impending failure modes has been studied. The results show that, at low mechanical-cyclic loads and low thermal-cyclic amplitudes, fatigue life for 0.999 reliability is most sensitive to matrix compressive strength, matrix modulus, thermal expansion coefficient, and ply thickness. Whereas at high mechanical-cyclic loads and high thermal-cyclic amplitudes, fatigue life at 0.999 reliability is more sensitive to the shear strength of matrix, longitudinal fiber modulus, matrix modulus, and ply thickness.

  5. Probabilistic Simulation of Combined Thermo-Mechanical Cyclic Fatigue in Composites

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    2010-01-01

    A methodology to compute probabilistically-combined thermo-mechanical fatigue life of polymer matrix laminated composites has been developed and is demonstrated. Matrix degradation effects caused by long-term environmental exposure and mechanical/thermal cyclic loads are accounted for in the simulation process. A unified time-temperature-stress-dependent multifactor-interaction relationship developed at NASA Glenn Research Center has been used to model the degradation/aging of material properties due to cyclic loads. The fast probability-integration method is used to compute probabilistic distribution of response. Sensitivities of fatigue life reliability to uncertainties in the primitive random variables (e.g., constituent properties, fiber volume ratio, void volume ratio, ply thickness, etc.) computed and their significance in the reliability-based design for maximum life is discussed. The effect of variation in the thermal cyclic loads on the fatigue reliability for a (0/+/-45/90)s graphite/epoxy laminate with a ply thickness of 0.127 mm, with respect to impending failure modes has been studied. The results show that, at low mechanical-cyclic loads and low thermal-cyclic amplitudes, fatigue life for 0.999 reliability is most sensitive to matrix compressive strength, matrix modulus, thermal expansion coefficient, and ply thickness. Whereas at high mechanical-cyclic loads and high thermal-cyclic amplitudes, fatigue life at 0.999 reliability is more sensitive to the shear strength of matrix, longitudinal fiber modulus, matrix modulus, and ply thickness.

  6. Quinolinic Acid, an endogenous molecule combining excitotoxicity, oxidative stress and other toxic mechanisms.

    PubMed

    Pérez-De La Cruz, Verónica; Carrillo-Mora, Paul; Santamaría, Abel

    2012-01-01

    Quinolinic acid (QUIN), an endogenous metabolite of the kynurenine pathway, is involved in several neurological disorders, including Huntington's disease, Alzheimer's disease, schizophrenia, HIV associated dementia (HAD) etc. QUIN toxicity involves several mechanisms which trigger various metabolic pathways and transcription factors. The primary mechanism exerted by this excitotoxin in the central nervous system (CNS) has been largely related with the overactivation of N-methyl-D-aspartate receptors and increased cytosolic Ca(2+) concentrations, followed by mitochondrial dysfunction, cytochrome c release, ATP exhaustion, free radical formation and oxidative damage. As a result, this toxic pattern is responsible for selective loss of middle size striatal spiny GABAergic neurons and motor alterations in lesioned animals. This toxin has recently gained attention in biomedical research as, in addition to its proven excitotoxic profile, a considerable amount of evidence suggests that oxidative stress and energetic disturbances are major constituents of its toxic pattern in the CNS. Hence, this profile has changed our perception of how QUIN-related disorders combine different toxic mechanisms resulting in brain damage. This review will focus on the description and integration of recent evidence supporting old and suggesting new mechanisms to explain QUIN toxicity.

  7. Quinolinic Acid, an Endogenous Molecule Combining Excitotoxicity, Oxidative Stress and Other Toxic Mechanisms

    PubMed Central

    Pérez-De La Cruz, Verónica; Carrillo-Mora, Paul; Santamaría, Abel

    2012-01-01

    Quinolinic acid (QUIN), an endogenous metabolite of the kynurenine pathway, is involved in several neurological disorders, including Huntington’s disease, Alzheimer’s disease, schizophrenia, HIV associated dementia (HAD) etc. QUIN toxicity involves several mechanisms which trigger various metabolic pathways and transcription factors. The primary mechanism exerted by this excitotoxin in the central nervous system (CNS) has been largely related with the overactivation of N-methyl-D-aspartate receptors and increased cytosolic Ca2+ concentrations, followed by mitochondrial dysfunction, cytochrome c release, ATP exhaustion, free radical formation and oxidative damage. As a result, this toxic pattern is responsible for selective loss of middle size striatal spiny GABAergic neurons and motor alterations in lesioned animals. This toxin has recently gained attention in biomedical research as, in addition to its proven excitotoxic profile, a considerable amount of evidence suggests that oxidative stress and energetic disturbances are major constituents of its toxic pattern in the CNS. Hence, this profile has changed our perception of how QUIN-related disorders combine different toxic mechanisms resulting in brain damage. This review will focus on the description and integration of recent evidence supporting old and suggesting new mechanisms to explain QUIN toxicity. PMID:22408367

  8. Solvent effect on the absorption spectra of coumarin 120 in water: A combined quantum mechanical and molecular mechanical study.

    PubMed

    Sakata, Tetsuya; Kawashima, Yukio; Nakano, Haruyuki

    2011-01-07

    The solvent effect on the absorption spectra of coumarin 120 (C120) in water was studied utilizing the combined quantum mechanical∕molecular mechanical (QM∕MM) method. In molecular dynamics (MD) simulation, a new sampling scheme was introduced to provide enough samples for both solute and solvent molecules to obtain the average physical properties of the molecules in solution. We sampled the structure of the solute and solvent molecules separately. First, we executed a QM∕MM MD simulation, where we sampled the solute molecule in solution. Next, we chose random solute structures from this simulation and performed classical MD simulation for each chosen solute structure with its geometry fixed. This new scheme allowed us to sample the solute molecule quantum mechanically and sample many solvent structures classically. Excitation energy calculations using the selected samples were carried out by the generalized multiconfigurational perturbation theory. We succeeded in constructing the absorption spectra and realizing the red shift of the absorption spectra found in polar solvents. To understand the motion of C120 in water, we carried out principal component analysis and found that the motion of the methyl group made the largest contribution and the motion of the amino group the second largest. The solvent effect on the absorption spectrum was studied by decomposing it in two components: the effect from the distortion of the solute molecule and the field effect from the solvent molecules. The solvent effect from the solvent molecules shows large contribution to the solvent shift of the peak of the absorption spectrum, while the solvent effect from the solute molecule shows no contribution. The solvent effect from the solute molecule mainly contributes to the broadening of the absorption spectrum. In the solvent effect, the variation in C-C bond length has the largest contribution on the absorption spectrum from the solute molecule. For the solvent effect on the

  9. Possible Peroxo State of the Dicopper Site of Particulate Methane Monooxygenase from Combined Quantum Mechanics and Molecular Mechanics Calculations.

    PubMed

    Itoyama, Shuhei; Doitomi, Kazuki; Kamachi, Takashi; Shiota, Yoshihito; Yoshizawa, Kazunari

    2016-03-21

    Enzymatic methane hydroxylation is proposed to efficiently occur at the dinuclear copper site of particulate methane monooxygenase (pMMO), which is an integral membrane metalloenzyme in methanotrophic bacteria. The resting state and a possible peroxo state of the dicopper active site of pMMO are discussed by using combined quantum mechanics and molecular mechanics calculations on the basis of reported X-ray crystal structures of the resting state of pMMO by Rosenzweig and co-workers. The dicopper site has a unique structure, in which one copper is coordinated by two histidine imidazoles and another is chelated by a histidine imidazole and primary amine of an N-terminal histidine. The resting state of the dicopper site is assignable to the mixed-valent Cu(I)Cu(II) state from a computed Cu-Cu distance of 2.62 Å from calculations at the B3LYP-D/TZVP level of theory. A μ-η(2):η(2)-peroxo-Cu(II)2 structure similar to those of hemocyanin and tyrosinase is reasonably obtained by using the resting state structure and dioxygen. Computed Cu-Cu and O-O distances are 3.63 and 1.46 Å, respectively, in the open-shell singlet state. Structural features of the dicopper peroxo species of pMMO are compared with those of hemocyanin and tyrosinase and synthetic dicopper model compounds. Optical features of the μ-η(2):η(2)-peroxo-Cu(II)2 state are calculated and analyzed with TD-DFT calculations.

  10. Left ventricular mechanics of counterpulsation and left heart bypass, individually and in combination.

    PubMed

    Rose, E A; Marrin, C A; Bregman, D; Spotnitz, H M

    1979-01-01

    Counterpulsation and left heart bypass devices have been successfully used to salvage patients with severe left ventricular power failure following cardiopulmonary bypass. Each of these techniques is believed to reduce or minimize myocardial work, yet the effects of these devices on the force of myocardial contraction have not been defined. In the present investigation the effects of counterpulsation produced by intravascular (intra-aortic balloon pumping) and extravascular (pulsatile assist device) balloon devices, partial left atrial-aortic bypass, and total bypass on left ventricular mechanics were examined. The devices were studied individually and in combination in 10 anesthetized open-chest dogs. Left ventricular wall stress, external work, and contractility indices were calculated by computer using a changing volume spherical model of the left ventricle. Results indicate that although all currently available circulatory assist devices reduced peak left ventricular wall stress, a spectrum of relative effectiveness progressed from intra-aortic balloon pumping or pulsatile assist device alone through the combination intra-aortic balloon pumping plus the pulsatile assist device. Partial left heart bypass was more effective than intra-aortic balloon pumping plus the pulsatile assist device in reducing peak wall stress, but the difference was small. Total left heart bypass was vastly superior to any of the other modalities tested in its effects on peak wall stress as well as external work. The addition of counterpulsation to partial or total left heart bypass produced minimal changes in left ventricular systolic mechanics.

  11. Evolution of water sorption in catalyst coated membranes subjected to combined chemical and mechanical degradation.

    PubMed

    Venkatesan, Senthil velan; Lim, Chan; Rogers, Erin; Holdcroft, Steven; Kjeang, Erik

    2015-06-07

    Catalyst coated perfluorosulfonic acid ionomer membranes (CCMs) were subjected to a combined chemical/mechanical accelerated stress test (AST) designed for rapid benchmarking of in situ membrane stability in polymer electrolyte fuel cells. In order to understand the evolution of the ionomer water sorption characteristics during combined chemical/mechanical degradation, CCM samples were periodically extracted from the AST and analyzed for ionomer mass fraction and water sorption properties. In spite of severe fluoride release and membrane thinning, the water uptake per unit mass of the partially degraded CCMs was found to be essentially constant. The mass fraction of ionomer in the CCM samples determined from thermogravimetric analysis (TGA) showed significant material loss throughout the AST process due to ionomer degradation and fluoride release, up to roughly 50% at end-of-life. The effects proceeding at different stages of degradation were therefore more accurately revealed by ionomer mass-normalized data. The water uptake per unit gram of ionomer was shown to increase significantly with degradation, in contrast to the previous results normalized by CCM dry mass. Although increased water sorption may indicate enlarged solvated hydrophilic domains in the membrane, which would be beneficial for enhanced proton mobility, the proton conductivity was found to decrease. This finding suggests that the additional water sorbed in the membrane was not contributing to proton conduction and was therefore likely situated in non-ionic cavities formed through degradation rather than in the ionic clusters.

  12. High-scale yield of nano hydroxyapatite through combination of mechanical activation and chemical dispersion.

    PubMed

    Gao, Xueling; Dai, Chunchu; Liu, Weiwei; Liu, Yumei; Shen, Ru; Zheng, Xiaotong; Duan, Ke; Weng, Jie; Qu, Shuxin

    2017-06-01

    The aim of this study is to develop a simple, convenient and effective approach to synthesize nano-sized hydroxyapatite (nano-HA) at high-scale yield. Nano-HA was wet synthesized in the presence or absence of alendronate sodium (ALN), one of bisphosphonates for anti-osteoporotic. Then aged and washed nano-HA precipitate was directly treated by mechanical activation combined with the chemical dispersion of ALN to prevent the agglomeration of nano-HA. ALN acted not only as a chemical dispersant but also as an orthopedic drug. In vitro release showed that ALN was released slowly from nano-HA. Transmission electron microscopy (TEM) revealed that nano-HA with size less than 100 nm appeared as single particle after being treated by mechanical activation combined with the dispersion of ALN (AMA-HA and MA-HA). High resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) confirmed that as-prepared nanoparticles were HA with low crystallinity and crystallite size. Fourier transform infrared spectroscopy (FTIR) indicated that the phosphonate groups in ALN were introduced to bond with the Ca(2+) of HA to impede the growth of HA crystal. Zeta potential illustrated that the absolute value of surface negative charge of nano-HA increased significantly with the addition of ALN, which inhibited the agglomeration of nano-HA. The present approach makes it feasible to produce nano-HA at high-scale yield, which provide the possibility to construct bone graft.

  13. Gemcitabine/cannabinoid combination triggers autophagy in pancreatic cancer cells through a ROS-mediated mechanism

    PubMed Central

    Donadelli, M; Dando, I; Zaniboni, T; Costanzo, C; Dalla Pozza, E; Scupoli, M T; Scarpa, A; Zappavigna, S; Marra, M; Abbruzzese, A; Bifulco, M; Caraglia, M; Palmieri, M

    2011-01-01

    Gemcitabine (GEM, 2′,2′-difluorodeoxycytidine) is currently used in advanced pancreatic adenocarcinoma, with a response rate of < 20%. The purpose of our work was to improve GEM activity by addition of cannabinoids. Here, we show that GEM induces both cannabinoid receptor-1 (CB1) and cannabinoid receptor-2 (CB2) receptors by an NF-κB-dependent mechanism and that its association with cannabinoids synergistically inhibits pancreatic adenocarcinoma cell growth and increases reactive oxygen species (ROS) induced by single treatments. The antiproliferative synergism is prevented by the radical scavenger N-acetyl--cysteine and by the specific NF-κB inhibitor BAY 11-7085, demonstrating that the induction of ROS by GEM/cannabinoids and of NF-κB by GEM is required for this effect. In addition, we report that neither apoptotic nor cytostatic mechanisms are responsible for the synergistic cell growth inhibition, which is strictly associated with the enhancement of endoplasmic reticulum stress and autophagic cell death. Noteworthy, the antiproliferative synergism is stronger in GEM-resistant pancreatic cancer cell lines compared with GEM-sensitive pancreatic cancer cell lines. The combined treatment strongly inhibits growth of human pancreatic tumor cells xenografted in nude mice without apparent toxic effects. These findings support a key role of the ROS-dependent activation of an autophagic program in the synergistic growth inhibition induced by GEM/cannabinoid combination in human pancreatic cancer cells. PMID:21525939

  14. Introduction of Enhanced Compressive Residual Stress Profiles in Aerospace Components Using Combined Mechanical Surface Treatments

    NASA Astrophysics Data System (ADS)

    Gopinath, Abhay; Lim, Andre; Nagarajan, Balasubramanian; Cher Wong, Chow; Maiti, Rajarshi; Castagne, Sylvie

    2016-11-01

    Mechanical surface treatments such as Shot Peening (SP) and Deep Cold Rolling (DCR) are being used to introduce Compressive Residual Stress (CRS) at the surface and subsurface layers of aerospace components, respectively. This paper investigates the feasibility of a combined introduction of both the surface and sub-surface compressive residual stress on Ti6Al4V material through a successive application of the two aforementioned processes, one after the other. CRS profiles between individual processes were compared to that of combination of processes to validate the feasibility. It was found out that shot peening introduces surface compressive residual stress into the already deep cold rolled sample, resulting in both surface and sub-surface compressive residual stresses in the material. However the drawback of such a combination would be the increased surface roughness after shot peening a deep cold rolled sample which can be critical especially in compressor components. Hence, a new technology, Vibro-Peening (VP) may be used as an alternative to SP to introduce surface stress at reduced roughness.

  15. A possible mechanism for combined arsenic and fluoride induced cellular and DNA damage in mice.

    PubMed

    Flora, Swaran J S; Mittal, Megha; Pachauri, Vidhu; Dwivedi, Nidhi

    2012-01-01

    Arsenic and fluoride are major contaminants of drinking water. Mechanisms of toxicity following individual exposure to arsenic or fluoride are well known. However, it is not explicit how combined exposure to arsenic and fluoride leads to cellular and/or DNA damage. The present study was planned to assess (i) oxidative stress during combined chronic exposure to arsenic and fluoride in drinking water, (ii) correlation of oxidative stress with cellular and DNA damage and (iii) mechanism of cellular damage using IR spectroscopy. Mice were exposed to arsenic and fluoride (50 ppm) either individually or in combination for 28 weeks. Arsenic or fluoride exposure individually led to a significant increase in reactive oxygen species (ROS) generation and associated oxidative stress in blood, liver and brain. Individual exposure to the two toxicants showed significant depletion of blood glutathione (GSH) and glucose 6-phosphate dehydrogenase (G6PD) activity, and single-stranded DNA damage using a comet assay in lymphocytes. We also observed an increase in the activity of ATPase, thiobarbituric acid reactive substance (TBARS) and a decreased, reduced and oxidized glutathione (GSH : GSSG) ratio in the liver and brain. Antioxidant enzymes like superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) were decreased and increased in liver and brain respectively. The changes were more pronounced in liver compared to brain suggesting liver to be more susceptible to the toxic effects of arsenic and fluoride. Interestingly, combined exposure to arsenic and fluoride resulted in less pronounced toxic effects compared to their individual effects based on biochemical variables, IR spectra, DNA damage (TUNEL and comet assays) and histopathological observations. IR spectra suggested that arsenic or fluoride perturbs the strength of protein and amide groups; however, the shifts in peaks were not pronounced during combined exposure. These results thus highlight the role of

  16. Insight into the Phosphodiesterase Mechanism from Combined QM/MM Free Energy Simulations

    PubMed Central

    Wong, Kin-Yiu; Gao, Jiali

    2011-01-01

    Summary Molecular dynamics simulations employing a combined quantum mechanical and molecular mechanical potential have been carried out to elucidate the reaction mechanism of the hydrolysis of a cyclic nucleotide cAMP substrate by phosphodiesterase 4B (PDE4B). PDE4B is a member of the PDE superfamily of enzymes that play crucial roles in cellular signal transduction. We have determined a two-dimensional potential of mean force for the coupled phosphoryl bond cleavage and proton transfer through a general acid catalysis mechanism in PDE4B. The results indicate that the ring-opening process takes place through an SN2 reaction mechanism, followed by a proton transfer to stabilize the leaving group. The computed free energy of activation for the PDE4B-catalyzed cAMP hydrolysis is about 13 kcal/mol and an overall reaction free energy is about −17 kcal/mol, both in accord with experimental results. In comparison with the uncatalyzed reaction in water, the enzyme PDE4B provides a strong stabilization of the transition state, lowering the free energy barrier by 14 kcal/mol. We found that the proton transfer from the general acid residue His234 to the O3' oxyanion of the ribosyl leaving group lags behind the nucleophilic attack, resulting in a shallow minimum on the free energy surface. A key contributing factor to transition state stabilization is the elongation of the distance between the divalent metal ions Zn2+ and Mg2+ in the active site as the reaction proceeds from the Michaelis complex to the transition state. PMID:21595828

  17. Mechanisms mediating enhanced neutralization efficacy of Staphylococcal enterotoxin B by combinations of monoclonal antibodies

    SciTech Connect

    Dutta, Kaushik; Varshney, Avanish K.; Franklin, Matthew C.; Goger, Michael; Wang, Xiaobo; Fries, Bettina C.

    2015-01-08

    Staphylococcal enterotoxin B (SEB) is a superantigen that cross-links the major histocompatibility complex class II and specific V-β chains of the T-cell receptor, thus forming a ternary complex. Developing neutralizing mAb to disrupt the ternary complex and abrogate the resulting toxicity is a major therapeutic challenge because SEB is effective at very low concentrations. We show that combining two SEB-specific mAbs enhances their efficacy, even though one of the two mAbs by itself has no effect on neutralization. Crystallography was employed for fine-mapping conformational epitopes in binary and ternary complexes between SEB and Fab fragments. NMR spectroscopy was used to validate and identify subtle allosteric changes induced by mAbs binding to SEB. The mapping of epitopes established that a combination of different mAbs can enhance efficacy of mAb-mediated protection from SEB induced lethal shock by two different mechanisms: one mAb mixture promoted clearance of the toxin both in vitro and in vivo by FcR-mediated cross-linking and clearance, whereas the other mAb mixture induced subtle allosteric conformational changes in SEB that perturbed formation of the SEB·T-cell receptor·major histocompatibility complex class II trimer. Lastly structural information accurately predicted mAb binding to other superantigens that share conformational epitopes with SEB. Fine mapping of conformational epitopes is a powerful tool to establish the mechanism and optimize the action of synergistic mAb combinations.

  18. Mechanisms mediating enhanced neutralization efficacy of Staphylococcal enterotoxin B by combinations of monoclonal antibodies

    DOE PAGES

    Dutta, Kaushik; Varshney, Avanish K.; Franklin, Matthew C.; ...

    2015-01-08

    Staphylococcal enterotoxin B (SEB) is a superantigen that cross-links the major histocompatibility complex class II and specific V-β chains of the T-cell receptor, thus forming a ternary complex. Developing neutralizing mAb to disrupt the ternary complex and abrogate the resulting toxicity is a major therapeutic challenge because SEB is effective at very low concentrations. We show that combining two SEB-specific mAbs enhances their efficacy, even though one of the two mAbs by itself has no effect on neutralization. Crystallography was employed for fine-mapping conformational epitopes in binary and ternary complexes between SEB and Fab fragments. NMR spectroscopy was used tomore » validate and identify subtle allosteric changes induced by mAbs binding to SEB. The mapping of epitopes established that a combination of different mAbs can enhance efficacy of mAb-mediated protection from SEB induced lethal shock by two different mechanisms: one mAb mixture promoted clearance of the toxin both in vitro and in vivo by FcR-mediated cross-linking and clearance, whereas the other mAb mixture induced subtle allosteric conformational changes in SEB that perturbed formation of the SEB·T-cell receptor·major histocompatibility complex class II trimer. Lastly structural information accurately predicted mAb binding to other superantigens that share conformational epitopes with SEB. Fine mapping of conformational epitopes is a powerful tool to establish the mechanism and optimize the action of synergistic mAb combinations.« less

  19. Mechanisms mediating enhanced neutralization efficacy of staphylococcal enterotoxin B by combinations of monoclonal antibodies.

    PubMed

    Dutta, Kaushik; Varshney, Avanish K; Franklin, Matthew C; Goger, Michael; Wang, Xiaobo; Fries, Bettina C

    2015-03-13

    Staphylococcal enterotoxin B (SEB) is a superantigen that cross-links the major histocompatibility complex class II and specific V-β chains of the T-cell receptor, thus forming a ternary complex. Developing neutralizing mAb to disrupt the ternary complex and abrogate the resulting toxicity is a major therapeutic challenge because SEB is effective at very low concentrations. We show that combining two SEB-specific mAbs enhances their efficacy, even though one of the two mAbs by itself has no effect on neutralization. Crystallography was employed for fine-mapping conformational epitopes in binary and ternary complexes between SEB and Fab fragments. NMR spectroscopy was used to validate and identify subtle allosteric changes induced by mAbs binding to SEB. The mapping of epitopes established that a combination of different mAbs can enhance efficacy of mAb-mediated protection from SEB induced lethal shock by two different mechanisms: one mAb mixture promoted clearance of the toxin both in vitro and in vivo by FcR-mediated cross-linking and clearance, whereas the other mAb mixture induced subtle allosteric conformational changes in SEB that perturbed formation of the SEB·T-cell receptor·major histocompatibility complex class II trimer. Finally structural information accurately predicted mAb binding to other superantigens that share conformational epitopes with SEB. Fine mapping of conformational epitopes is a powerful tool to establish the mechanism and optimize the action of synergistic mAb combinations.

  20. Keratinocyte galvanotaxis in combined DC and AC electric fields supports an electromechanical transduction sensing mechanism.

    PubMed

    Hart, Francis X; Laird, Mhairi; Riding, Aimie; Pullar, Christine E

    2013-02-01

    Sedentary keratinocytes at the edge of a skin wound migrate into the wound, guided by the generation of an endogenous electric field (EF) generated by the collapse of the transepithelial potential. The center of the wound quickly becomes more negative than the surrounding tissue and remains the cathode of the endogenous EF until the wound is completely re-epithelialized. This endogenous guidance cue can be studied in vitro. When placed in a direct current (DC) EF of physiological strength, 100 V/m, keratinocytes migrate directionally toward the cathode in a process known as galvanotaxis. Although a number of membrane-bound (e.g., epidermal growth factor receptor (EGFR), integrins) and cytosolic proteins (cAMP, ERK, PI3K) are known to play a role in the downstream signaling mechanisms underpinning galvanotaxis, the initial sensing mechanism for this response is not understood. To investigate the EF sensor, we studied the migration of keratinocytes in a DC EF of 100 V/m, alternating current (AC) EFs of 40 V/m at either 1.6 or 160 Hz, and combinations of DC and AC EFs. In the AC EFs alone, keratinocytes migrated randomly. The 1.6 Hz AC EF combined with the DC EF suppressed the direction of migration but had no effect on speed. In contrast, the 160 Hz AC EF combined with the DC EF did not affect the direction of migration but increased the migration speed compared to the DC EF alone. These results can be understood in terms of an electromechanical transduction model, but not an electrodiffusion/osmosis or a voltage-gated channel model. Copyright © 2012 Wiley Periodicals, Inc.

  1. Mechanism of bacterial inactivation by (+)-limonene and its potential use in food preservation combined processes.

    PubMed

    Espina, Laura; Gelaw, Tilahun K; de Lamo-Castellví, Sílvia; Pagán, Rafael; García-Gonzalo, Diego

    2013-01-01

    This work explores the bactericidal effect of (+)-limonene, the major constituent of citrus fruits' essential oils, against E. coli. The degree of E. coli BJ4 inactivation achieved by (+)-limonene was influenced by the pH of the treatment medium, being more bactericidal at pH 4.0 than at pH 7.0. Deletion of rpoS and exposure to a sub-lethal heat or an acid shock did not modify E. coli BJ4 resistance to (+)-limonene. However, exposure to a sub-lethal cold shock decreased its resistance to (+)-limonene. Although no sub-lethal injury was detected in the cell envelopes after exposure to (+)-limonene by the selective-plating technique, the uptake of propidium iodide by inactivated E. coli BJ4 cells pointed out these structures as important targets in the mechanism of action. Attenuated Total Reflectance Infrared Microspectroscopy (ATR-IRMS) allowed identification of altered E. coli BJ4 structures after (+)-limonene treatments as a function of the treatment pH: β-sheet proteins at pH 4.0 and phosphodiester bonds at pH 7.0. The increased sensitivity to (+)-limonene observed at pH 4.0 in an E. coli MC4100 lptD4213 mutant with an increased outer membrane permeability along with the identification of altered β-sheet proteins by ATR-IRMS indicated the importance of this structure in the mechanism of action of (+)-limonene. The study of mechanism of inactivation by (+)-limonene led to the design of a synergistic combined process with heat for the inactivation of the pathogen E. coli O157:H7 in fruit juices. These results show the potential of (+)-limonene in food preservation, either acting alone or in combination with lethal heat treatments.

  2. Mechanism of Bacterial Inactivation by (+)-Limonene and Its Potential Use in Food Preservation Combined Processes

    PubMed Central

    Espina, Laura; Gelaw, Tilahun K.; de Lamo-Castellví, Sílvia; Pagán, Rafael; García-Gonzalo, Diego

    2013-01-01

    This work explores the bactericidal effect of (+)-limonene, the major constituent of citrus fruits' essential oils, against E. coli. The degree of E. coli BJ4 inactivation achieved by (+)-limonene was influenced by the pH of the treatment medium, being more bactericidal at pH 4.0 than at pH 7.0. Deletion of rpoS and exposure to a sub-lethal heat or an acid shock did not modify E. coli BJ4 resistance to (+)-limonene. However, exposure to a sub-lethal cold shock decreased its resistance to (+)-limonene. Although no sub-lethal injury was detected in the cell envelopes after exposure to (+)-limonene by the selective-plating technique, the uptake of propidium iodide by inactivated E. coli BJ4 cells pointed out these structures as important targets in the mechanism of action. Attenuated Total Reflectance Infrared Microspectroscopy (ATR-IRMS) allowed identification of altered E. coli BJ4 structures after (+)-limonene treatments as a function of the treatment pH: β-sheet proteins at pH 4.0 and phosphodiester bonds at pH 7.0. The increased sensitivity to (+)-limonene observed at pH 4.0 in an E. coli MC4100 lptD4213 mutant with an increased outer membrane permeability along with the identification of altered β-sheet proteins by ATR-IRMS indicated the importance of this structure in the mechanism of action of (+)-limonene. The study of mechanism of inactivation by (+)-limonene led to the design of a synergistic combined process with heat for the inactivation of the pathogen E. coli O157:H7 in fruit juices. These results show the potential of (+)-limonene in food preservation, either acting alone or in combination with lethal heat treatments. PMID:23424676

  3. Aspiration Thrombectomy and Drug-Eluting Stent Implantation Decrease the Occurrence of Angina Pectoris One Year After Acute Myocardial Infarction

    PubMed Central

    Lee, Wei-Chieh; Fang, Chih-Yuan; Chen, Huang-Chung; Hsueh, Shu-Kai; Chen, Chien-Jen; Yang, Cheng-Hsu; Yip, Hon-Kan; Hang, Chi-Ling; Wu, Chiung-Jen; Fang, Hsiu-Yu

    2016-01-01

    Abstract Angina pectoris is a treatable symptom that is associated with mortality and decreased quality of life. Angina eradication is a primary care goal of care after an acute myocardial infarction (AMI). Our aim was to evaluate factors influencing angina pectoris 1 year after an AMI. From January 2005 to December 2013, 1547 patient received primary percutaneous intervention in our hospital for an acute ST-segment elevation myocardial infarction (MI). Of these patients, 1336 patients did not experience post-MI angina during a 1-year follow-up, and 211 patients did. Univariate and multivariate logistic regression analyses were performed to identify the factors influencing angina pectoris 1 year after an AMI. Propensity score matched analyses were performed for subgroups analyses. The average age of the patients was 61.08 ± 12.77 years, with a range of 25 to 97 years, and 82.9% of the patients were male. During 1-year follow-up, 13.6% of the patients experienced post-MI angina. There was a longer chest pain-to-reperfusion time in the post-MI angina group (P = 0.01), as well as a higher fasting sugar level, glycohemoglobin (HbA1C), serum creatinine, troponin-I and creatine kinase MB (CK-MB). The post-MI angina group also had a higher prevalence of multiple-vessel disease. Manual thrombectomy, and distal protective device and intracoronary glycoprotein IIb/IIIa inhibitor injection were used frequently in the no post-MI angina group. Antiplatelet agents and post-MI medication usage were similar between the 2 groups. Multivariate logistic regression analyses demonstrated that prior MI was a positive independent predictor of occurrence of post-MI angina. Manual thrombectomy use and drug-eluting stent implantation were negative independent predictors of post-MI angina. Higher troponin-I and longer chest pain-to-reperfusion time exhibited a trend toward predicting post-MI angina. Prior MIs were strong, independent predictors of post-MI angina. Manual thrombectomy

  4. Aspiration Thrombectomy and Drug-Eluting Stent Implantation Decrease the Occurrence of Angina Pectoris One Year After Acute Myocardial Infarction.

    PubMed

    Lee, Wei-Chieh; Fang, Chih-Yuan; Chen, Huang-Chung; Hsueh, Shu-Kai; Chen, Chien-Jen; Yang, Cheng-Hsu; Yip, Hon-Kan; Hang, Chi-Ling; Wu, Chiung-Jen; Fang, Hsiu-Yu

    2016-04-01

    Angina pectoris is a treatable symptom that is associated with mortality and decreased quality of life. Angina eradication is a primary care goal of care after an acute myocardial infarction (AMI). Our aim was to evaluate factors influencing angina pectoris 1 year after an AMI.From January 2005 to December 2013, 1547 patient received primary percutaneous intervention in our hospital for an acute ST-segment elevation myocardial infarction (MI). Of these patients, 1336 patients did not experience post-MI angina during a 1-year follow-up, and 211 patients did. Univariate and multivariate logistic regression analyses were performed to identify the factors influencing angina pectoris 1 year after an AMI. Propensity score matched analyses were performed for subgroups analyses.The average age of the patients was 61.08 ± 12.77 years, with a range of 25 to 97 years, and 82.9% of the patients were male. During 1-year follow-up, 13.6% of the patients experienced post-MI angina. There was a longer chest pain-to-reperfusion time in the post-MI angina group (P = 0.01), as well as a higher fasting sugar level, glycohemoglobin (HbA1C), serum creatinine, troponin-I and creatine kinase MB (CK-MB). The post-MI angina group also had a higher prevalence of multiple-vessel disease. Manual thrombectomy, and distal protective device and intracoronary glycoprotein IIb/IIIa inhibitor injection were used frequently in the no post-MI angina group. Antiplatelet agents and post-MI medication usage were similar between the 2 groups. Multivariate logistic regression analyses demonstrated that prior MI was a positive independent predictor of occurrence of post-MI angina. Manual thrombectomy use and drug-eluting stent implantation were negative independent predictors of post-MI angina. Higher troponin-I and longer chest pain-to-reperfusion time exhibited a trend toward predicting post-MI angina.Prior MIs were strong, independent predictors of post-MI angina. Manual thrombectomy and drug

  5. Hybrid operative thrombectomy is noninferior to percutaneous techniques for the treatment of acute iliofemoral deep venous thrombosis.

    PubMed

    Rodríguez, Limael E; Aboukheir-Aboukheir, Aihab; Figueroa-Vicente, Ricardo; Soler-Bernardini, Hiram; Bolanos-Avila, Guillermo; Torruella-Bartolomei, Luis J; Comerota, Anthony J; Martinez-Trabal, Jorge L

    2017-03-01

    Hybrid operative thrombectomy (HOT) is a novel technique for the treatment of acute iliofemoral deep venous thrombosis (IFDVT) and is an alternative to percutaneous techniques (PTs) that use thrombolytics. In this study, we compare perioperative and intermediate outcomes of HOT vs PT as interventions for early thrombus removal. From July 2008 to May 2015, there were 71 consecutive patients who were treated with either PT (n = 31) or HOT (n = 40) for acute or subacute single-limb IFDVT. HOT consisted of surgical thrombectomy with balloon angioplasty with or without stenting by a single incision and fluoroscopically guided retrograde valve manipulation to extract the thrombus. PT included catheter-directed thrombolysis with or without pharmacomechanical thrombectomy using the Trellis-8 system (Bacchus Vascular, Santa Clara, Calif). Patients who presented with bilateral DVT (n = 4), inferior vena cava involvement (n = 8), or venous gangrene (n = 1) were excluded. Perioperative outcomes, quality measures, and thrombus resolution were compared between the two treatment groups. Clinical, Etiology, Anatomy, and Pathophysiology (CEAP) classification, Villalta score, and venous duplex ultrasound at intermediate follow-up were also analyzed. The left limb was the most common site of the IFDVT overall. Technical success (≥50% resolution) was 100% for both groups, and >80% resolution was achieved in all patients treated with HOT. There were eight major bleeding events in the PT group compared with three in the HOT group (P = .04). PT patients had a significantly longer length of stay (13 vs 10 days; P = .028) compared with HOT. At 2-year duplex ultrasound examination, there was no difference between HOT and PT in mean reflux times at the femoral-popliteal segment. At 2 years, 85% and 87% of the patients (HOT vs PT, respectively) had not developed post-thrombotic syndrome, and there was no difference between the groups for mean Villalta score (2.1 ± 1.9 vs 2.3 ± 2

  6. Reaction mechanisms of aqueous monoethanolamine with carbon dioxide: a combined quantum chemical and molecular dynamics study.

    PubMed

    Hwang, Gyeong S; Stowe, Haley M; Paek, Eunsu; Manogaran, Dhivya

    2015-01-14

    Aqueous monoethanolamine (MEA) has been extensively studied as a solvent for CO2 capture, yet the underlying reaction mechanisms are still not fully understood. Combined ab initio and classical molecular dynamics simulations were performed to revisit and identify key elementary reactions and intermediates in 25-30 wt% aqueous MEA with CO2, by explicitly taking into account the structural and dynamic effects. Using static quantum chemical calculations, we also analyzed in more detail the fundamental interactions involved in the MEA-CO2 reaction. We find that both the CO2 capture by MEA and solvent regeneration follow a zwitterion-mediated two-step mechanism; from the zwitterionic intermediate, the relative probability between deprotonation (carbamate formation) and CO2 removal (MEA regeneration) tends to be determined largely by the interaction between the zwitterion and neighboring H2O molecules. In addition, our calculations clearly demonstrate that proton transfer in the MEA-CO2-H2O solution primarily occurs through H-bonded water bridges, and thus the availability and arrangement of H2O molecules also directly impacts the protonation and/or deprotonation of MEA and its derivatives. This improved understanding should contribute to developing more comprehensive kinetic models for use in modeling and optimizing the CO2 capture process. Moreover, this work highlights the importance of a detailed atomic-level description of the solution structure and dynamics in order to better understand molecular mechanisms underlying the reaction of CO2 with aqueous amines.

  7. Mechanisms of Donor-Specific Tolerance in Recipients of Haploidentical Combined Bone Marrow/Kidney Transplantation

    PubMed Central

    Andreola, G.; Chittenden, M.; Shaffer, J.; Cosimi, A.B.; Kawai, T.; Cotter, P.; LoCascio, S.A.; Morokata, T.; Dey, B.R.; Tolkoff-Rubin, N.T.; Preffer, F.; Bonnefoix, T.; Kattleman, K.; Spitzer, T.R.; Sachs, D.H.; Sykes, M.

    2011-01-01

    We recently reported long-term organ allograft survival without ongoing immunosuppression in 4 of 5 patients receiving combined kidney and bone marrow transplantation from haploidentical donors following non-myeloablative conditioning. In vitro assays up to 18 months revealed donor-specific unresponsiveness. We now demonstrate that T cell recovery is gradual and is characterized by memory-type cell predominance and an increased proportion of CD4+CD25+CD127−FOXP3+ Treg during the lymphopenic period. Complete donor-specific unresponsiveness in proliferative and cytotoxic assays, and in limiting dilution analyses of IL-2-producing and cytotoxic cells, developed and persisted for the 3-year follow-up in all patients, and extended to donor renal tubular epithelial cells. Assays in 2 of 4 patients were consistent with a role for a suppressive tolerance mechanism at 6 months to 1 year, but later (≥18 months) studies on all 4 patients provided no evidence for a suppressive mechanism. Our studies demonstrate, for the first time, long-term, systemic donor-specific unresponsiveness in patients with HLA-mismatched allograft tolerance. While regulatory cells may play an early role, long-term tolerance appears to be maintained by a deletion or anergy mechanism. PMID:21645255

  8. Selecting optimal combinations of transcription factors to promote axon regeneration: Why mechanisms matter.

    PubMed

    Venkatesh, Ishwariya; Blackmore, Murray G

    2016-12-23

    Recovery from injuries to the central nervous system, including spinal cord injury, is constrained in part by the intrinsically low ability of many CNS neurons to mount an effective regenerative growth response. To improve outcomes, it is essential to understand and ultimately reverse these neuron-intrinsic constraints. Genetic manipulation of key transcription factors (TFs), which act to orchestrate production of multiple regeneration-associated genes, has emerged as a promising strategy. It is likely that no single TF will be sufficient to fully restore neuron-intrinsic growth potential, and that multiple, functionally interacting factors will be needed. An extensive literature, mostly from non-neural cell types, has identified potential mechanisms by which TFs can functionally synergize. Here we examine four potential mechanisms of TF/TF interaction; physical interaction, transcriptional cross-regulation, signaling-based cross regulation, and co-occupancy of regulatory DNA. For each mechanism, we consider how existing knowledge can be used to guide the discovery and effective use of TF combinations in the context of regenerative neuroscience. This mechanistic insight into TF interactions is needed to accelerate the design of effective TF-based interventions to relieve neuron-intrinsic constraints to regeneration and to foster recovery from CNS injury.

  9. Mechanism of red mud combined with Fenton's reagent in sewage sludge conditioning.

    PubMed

    Zhang, Hao; Yang, Jiakuan; Yu, Wenbo; Luo, Sen; Peng, Li; Shen, Xingxing; Shi, Yafei; Zhang, Shinan; Song, Jian; Ye, Nan; Li, Ye; Yang, Changzhu; Liang, Sha

    2014-08-01

    Red mud was evaluated as an alternative skeleton builder combined with Fenton's reagent in sewage sludge conditioning. The results show that red mud combined with Fenton's reagent showed good conditioning capability with the pH of the filtrate close to neutrality, indicating that red mud acted as a neutralizer as well as a skeleton builder when jointly used with Fenton's reagent. Through response surface methodology (RSM), the optimal dosages of Fe(2+), H2O2 and red mud were proposed as 31.9, 33.7 and 275.1 mg/g DS (dry solids), respectively. The mechanism of the composite conditioner could be illuminated as follows: (1) extracellular polymeric substances (EPS), including loosely bound EPS and tightly bound EPS, were degraded into dissolved organics, e.g., proteins and polysaccharides; (2) bound water was released and converted into free water due to the degradation of EPS; and (3) morphology of the conditioned sludge exhibited a porous structure in contrast with the compact structure of raw sludge, and the addition of red mud formed new mineral phases and a rigid lattice structure in sludge, allowing the outflow of free water. Thus, sludge dewatering performance was effectively improved. The economic assessment for a wastewater treatment plant of 370,000 equivalent inhabitants confirms that using red mud conditioning, combined with Fenton's reagent, leads to a saving of approximately 411,000 USD/y or 50.8 USD/t DS comparing with using lime and ordinary Portland cement combined with Fenton's reagent, and approximately 612,000 USD/y or 75.5 USD/t DS comparing with the traditional treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. [NB4 cell apoptosis induced by bortezomib combined with As(2)O(3) and its mechanism].

    PubMed

    Chen, Xiao-Wen; Xia, Hai-Long; Xia, Rui-Xiang

    2011-04-01

    This study was aimed to investigate the apoptosis induced by bortezomib combined with As(2)O(3) in APL cell line NB4 and its mechanism. The apoptotic cells were detected by flow cytometry with Annexin V/propidium iodide double staining; the morphology of apoptotic cells was observed by Hoechst staining, Western blot was used to measure activation of caspase-3 and -9 as well as expression of NOXA; the siRNA technique was used to specifically silence NOXA gene; the lipofectamine 2000 was used to transfect pEGFP-Noxa plasmid and pEGFP vacant vector. The results showed that the bortezomib combined with As(2)O(3) could induce significant apoptosis of NB4 cells and activation of caspase 3 and caspase 9, but As(2)O(3) (0.5 µmol/L) alone could not cause marked activation of caspase cascade and apoptosis of NB4 cells. The expression level of NOXA in NB4 cells induced by bortezomib combined with As(2)O(3) was up-regulated; the activation level of caspase-3 and apoptotic rate of NB4 cells treated by bortezomib combined with As(2)O(3) decreased after specifically silencing the NOXA gene. The high expression of NOXA induced by transfection of plasmid could enhance the caspase 3 activity induced by As(2)O(3) alone. It is concluded that bortezomib can enhance sensitivity of NB4 cells to apoptosis induced by As(2)O(3) which may be related with up-regulation of proapoptotic protein NOXA.

  11. Efficacy of Stent-Retriever Thrombectomy in Magnetic Resonance Imaging Versus Computed Tomographic Perfusion-Selected Patients in SWIFT PRIME Trial (Solitaire FR With the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke).

    PubMed

    Menjot de Champfleur, Nicolas; Saver, Jeffrey L; Goyal, Mayank; Jahan, Reza; Diener, Hans-Christoph; Bonafe, Alain; Levy, Elad I; Pereira, Vitor M; Cognard, Christophe; Yavagal, Dileep R; Albers, Gregory W

    2017-06-01

    The majority of patients enrolled in SWIFT PRIME trial (Solitaire FR With the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke) had computed tomographic perfusion (CTP) imaging before randomization; 34 patients were randomized after magnetic resonance imaging (MRI). Patients with middle cerebral artery and distal carotid occlusions were randomized to treatment with tPA (tissue-type plasminogen activator) alone or tPA+stentriever thrombectomy. The primary outcome was the distribution of the modified Rankin Scale score at 90 days. Patients with the target mismatch profile for enrollment were identified on MRI and CTP. MRI selection was performed in 34 patients; CTP in 139 patients. Baseline National Institutes of Health Stroke Scale score was 17 in both groups. Target mismatch profile was present in 95% (MRI) versus 83% (CTP). A higher percentage of the MRI group was transferred from an outside hospital (P=0.02), and therefore, the time from stroke onset to randomization was longer in the MRI group (P=0.003). Time from emergency room arrival to randomization did not differ in CTP versus MRI-selected patients. Baseline ischemic core volumes were similar in both groups. Reperfusion rates (>90%/TICI [Thrombolysis in Cerebral Infarction] score 3) did not differ in the stentriever-treated patients in the MRI versus CTP groups. The primary efficacy analysis (90-day mRS score) demonstrated a statistically significant benefit in both subgroups (MRI, P=0.02; CTP, P=0.01). Infarct growth was reduced in the stentriever-treated group in both MRI and CTP groups. Time to randomization was significantly longer in MRI-selected patients; however, site arrival to randomization times were not prolonged, and the benefits of endovascular therapy were similar. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01657461. © 2017 American Heart Association, Inc.

  12. Immuno-pharmacodynamics for evaluating mechanism of action and developing immunotherapy combinations.

    PubMed

    Parchment, Ralph E; Voth, Andrea Regier; Doroshow, James H; Berzofsky, Jay A

    2016-08-01

    Immunotherapy has become a major modality of cancer treatment, with multiple new classes of immunotherapeutics recently entering the clinic and obtaining market approval from regulatory agencies. While the promise of these therapies is great, so is the number of possible combinations not only with each other but also with small molecule therapeutics. Furthermore, the observation of unusual dose-response relationships suggests a critical dependency of drug effectiveness on the dosage regimen (dose and schedule). Clinical pharmacodynamic (PD) biomarkers will be useful endpoints for confirming drug mechanism of action, evaluating combination therapies for synergy or antagonism, and identifying optimal dosage regimens. In contrast to conventional PD in which drug action occurs entirely within a single target cell (ie, is self-contained within the malignant cell), immunotherapy involves a complex mechanism of action with sequential steps that propagate through multiple cell types, both normal and malignant. Its intercellular pharmacology begins with molecular target engagement either on an immune effector cell or a malignant cell, followed by stimulatory biochemical and biological signals in immune effector cells, and then finally ends with activation of cell death mechanisms in malignant cells lying within a certain distance from the activated effector cells (immune cell-tumor cell proximity). Evaluating such "trans-cellular pharmacology," in which different steps of drug action are distributed across multiple cell types, requires novel microscopy and image analysis tools capable of quantifying PD-biomarker responses, mapping the responses onto the cellular geography of the tumor using phenotypic biomarkers to identify specific cell types, and finally analyzing the spatial relationships between biomarkers in the context of each cell's biological role. We have termed this form of nearest neighbor image analysis of drug action "proximity PD microscopy," to indicate the

  13. Mechanically fastened composite laminates subjected to combined bearing-bypass and shear loading

    NASA Technical Reports Server (NTRS)

    Madenci, Erdogan

    1993-01-01

    Bolts and rivets provide a means of load transfer in the construction of aircraft. However, they give rise to stress concentrations and are often the source and location of static and fatigue failures. Furthermore, fastener holes are prone to cracks during take-off and landing. These cracks present the most common origin of structural failures in aircraft. Therefore, accurate determination of the contact stresses associated with such loaded holes in mechanically fastened joints is essential to reliable strength evaluation and failure prediction. As the laminate is subjected to loading, the contact region, whose extent is not known, develops between the fastener and the hole boundary through this contact region, which consists of slip and no-slip zones due to friction. The presence of the unknown contact stress distribution over the contact region between the pin and the composite laminate, material anisotropy, friction between the pin and the laminate, pin-hole clearance, combined bearing-bypass and shear loading, and finite geometry of the laminate result in a complex non-linear problem. In the case of bearing-bypass loading in compression, this non-linear problem is further complicated by the presence of dual contact regions. Previous research concerning the analysis of mechanical joints subjected to combined bearing-bypass and shear loading is non-existent. In the case of bearing-bypass loading only, except for the study conducted by Naik and Crews (1991), others employed the concept of superposition which is not valid for this non-linear problem. Naik and Crews applied a linear finite element analysis with conditions along the pin-hole contact region specified as displacement constraint equations. The major shortcoming of this method is that the variation of the contract region as a function of the applied load should be known a priori. Also, their analysis is limited to symmetric geometry and material systems, and frictionless boundary conditions. Since the

  14. Network bursting dynamics in excitatory cortical neuron cultures results from the combination of different adaptive mechanisms.

    PubMed

    Masquelier, Timothée; Deco, Gustavo

    2013-01-01

    In the brain, synchronization among cells of an assembly is a common phenomenon, and thought to be functionally relevant. Here we used an in vitro experimental model of cell assemblies, cortical cultures, combined with numerical simulations of a spiking neural network (SNN) to investigate how and why spontaneous synchronization occurs. In order to deal with excitation only, we pharmacologically blocked GABAAergic transmission using bicuculline. Synchronous events in cortical cultures tend to involve almost every cell and to display relatively constant durations. We have thus named these "network spikes" (NS). The inter-NS-intervals (INSIs) proved to be a more interesting phenomenon. In most cortical cultures NSs typically come in series or bursts ("bursts of NSs", BNS), with short (~1 s) INSIs and separated by long silent intervals (tens of s), which leads to bimodal INSI distributions. This suggests that a facilitating mechanism is at work, presumably short-term synaptic facilitation, as well as two fatigue mechanisms: one with a short timescale, presumably short-term synaptic depression, and another one with a longer timescale, presumably cellular adaptation. We thus incorporated these three mechanisms into the SNN, which, indeed, produced realistic BNSs. Next, we systematically varied the recurrent excitation for various adaptation timescales. Strong excitability led to frequent, quasi-periodic BNSs (CV~0), and weak excitability led to rare BNSs, approaching a Poisson process (CV~1). Experimental cultures appear to operate within an intermediate weakly-synchronized regime (CV~0.5), with an adaptation timescale in the 2-8 s range, and well described by a Poisson-with-refractory-period model. Taken together, our results demonstrate that the INSI statistics are indeed informative: they allowed us to infer the mechanisms at work, and many parameters that we cannot access experimentally.

  15. Combination of Oral Antibiotics and Mechanical Bowel Preparation Reduces Surgical Site Infection in Colorectal Surgery.

    PubMed

    Ohman, Kerri A; Wan, Leping; Guthrie, Tracey; Johnston, Bonnie; Leinicke, Jennifer A; Glasgow, Sean C; Hunt, Steven R; Mutch, Matthew G; Wise, Paul E; Silviera, Matthew L

    2017-10-01

    Surgical site infections (SSI) are a common complication after colorectal surgery. An infection prevention bundle (IPB) was implemented to improve outcomes. A standardized IPB that included the administration of oral antibiotics with a mechanical bowel preparation, preoperative shower with chlorhexidine, hair removal and skin preparation in holding, antibiotic wound irrigation, and a "clean-closure" protocol was implemented in January 2013. Data from the American College of Surgeons NSQIP were analyzed at a single academic institution to compare pre-IPB and post-IPB SSI rates. In January 2014, a prospective database was implemented to determine compliance with individual IPB elements and their effect on outcomes. For the 24 months pre-IPB, the overall SSI rate was 19.7%. During the 30 months after IPB implementation, the SSI rate decreased to 8.2% (p < 0.0001). A subset of 307 patients was identified in both NSQIP and our prospective compliance databases. Elements of IPB associated with decreased SSI rates included preoperative shower with chlorhexidine (4.6% vs 16.2%; p = 0.005), oral antibiotics (3.4% vs 15.4%; p < 0.001), and mechanical bowel preparation (4.4% vs 14.3%; p = 0.008). Patients who received a full bowel preparation of both oral antibiotics and a mechanical bowel preparation had a 2.7% SSI rate compared with 15.8% for all others (p < 0.001). On multivariate analysis, full bowel preparation was independently associated with significantly fewer SSI (adjusted odds ratio 0.2; 95% CI 0.1 to 0.9; p = 0.006). Implementation of an IPB was successful in decreasing SSI rates in colorectal surgery patients. The combination of oral antibiotics with a mechanical bowel preparation was the strongest predictor of decreased SSI. Copyright © 2017 American College of Surgeons. All rights reserved.

  16. Network Bursting Dynamics in Excitatory Cortical Neuron Cultures Results from the Combination of Different Adaptive Mechanism

    PubMed Central

    Masquelier, Timothée; Deco, Gustavo

    2013-01-01

    In the brain, synchronization among cells of an assembly is a common phenomenon, and thought to be functionally relevant. Here we used an in vitro experimental model of cell assemblies, cortical cultures, combined with numerical simulations of a spiking neural network (SNN) to investigate how and why spontaneous synchronization occurs. In order to deal with excitation only, we pharmacologically blocked GABAAergic transmission using bicuculline. Synchronous events in cortical cultures tend to involve almost every cell and to display relatively constant durations. We have thus named these “network spikes” (NS). The inter-NS-intervals (INSIs) proved to be a more interesting phenomenon. In most cortical cultures NSs typically come in series or bursts (“bursts of NSs”, BNS), with short (∼1 s) INSIs and separated by long silent intervals (tens of s), which leads to bimodal INSI distributions. This suggests that a facilitating mechanism is at work, presumably short-term synaptic facilitation, as well as two fatigue mechanisms: one with a short timescale, presumably short-term synaptic depression, and another one with a longer timescale, presumably cellular adaptation. We thus incorporated these three mechanisms into the SNN, which, indeed, produced realistic BNSs. Next, we systematically varied the recurrent excitation for various adaptation timescales. Strong excitability led to frequent, quasi-periodic BNSs (CV∼0), and weak excitability led to rare BNSs, approaching a Poisson process (CV∼1). Experimental cultures appear to operate within an intermediate weakly-synchronized regime (CV∼0.5), with an adaptation timescale in the 2–8 s range, and well described by a Poisson-with-refractory-period model. Taken together, our results demonstrate that the INSI statistics are indeed informative: they allowed us to infer the mechanisms at work, and many parameters that we cannot access experimentally. PMID:24146781

  17. Combined biaxial and uniaxial mechanical characterization of prosthetic meshes in a rabbit model.

    PubMed

    Röhrnbauer, B; Ozog, Y; Egger, J; Werbrouck, E; Deprest, J; Mazza, E

    2013-06-21

    The present experimental study is aimed at a combined uniaxial and biaxial mechanical characterization of the deformation behavior of two types of prosthetic meshes, SPMM (heavy-weight) and Gynemesh M (light-weight, partly absorbable), after integration in the host tissue. Explants from a full-thickness-abdominal-wall-defect-rabbit-model were tested in the two loading conditions. Corresponding protocols and data analysis procedures for biaxial inflation tests and uniaxial tensile tests were developed. Biaxial responses were observed to be by factor 2-4 stiffer compared to corresponding uniaxial experiments, depending on the material tested. In biaxial loading conditions, SPMM explants were stiffest. Gynemesh M explants and native tissue were similarly compliant at low membrane tensions (<5N/cm) (abdominal wall: 40±23N/cm, Gynemesh M: 59±44N/cm, SPMM: 145±36N/cm). At high membrane tensions (>5N/cm), there were distinct differences in the stiffness of the three groups, SPMM explants being the stiffest, followed by Gynemesh M explants and native tissue being the most compliant. In uniaxial loading conditions, the two explants were similarly stiff and distinctly stiffer than native tissue at low membrane tensions (<5N/cm) (abdominal wall: 9±1N/cm, Gynemesh M: 21±5N/cm, and SPMM: 24±5N/cm). At high membrane tension (>5N/cm), differences between all groups vanished. Biaxial and uniaxial tests yield different results with respect to the mechanical behavior of mesh explants. These findings demonstrate that an evaluation of the mechanical biocompatibility of prosthetic meshes should be based on an experimental configuration (uniaxial or biaxial tension) which reproduces the expected in vivo conditions of mechanical loading and deformation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Combined spectroscopic study on the growth mechanism of Diphosphine-stabilized Gold Nanoclusters

    NASA Astrophysics Data System (ADS)

    Bao, Jie; Yang, Lina; Liu, Wei; Huang, Yuanyuan; Huang, Ting; Cao, Yuanjie; Yao, Tao; Sun, Zhihu; Wei, Shiqiang

    2016-05-01

    The formation process of 1,5-Bis(diphenylphosphino) pentane (L5)-protected Au nanocluster through the reduction of precursor Au2L5Cl2 by borane-tert-butylamine (TBAB) is traced by a combination of time-dependent x-ray/UV-vis absorption spectroscopies and mass spectrometry. It is revealed that the initial generation of dual-core basic unit Au4L5 2Cl is a critical step, which allows for a subsequent size-growth process via incorporation of the existing Au monomer (Au(I)-Cl) or Au2L5 to form Au5L5 2, Au8L5 3Cl, Au10L5 4Cl and finally main Au11L5 4Cl2 This work advances one step further toward understanding the mechanism of formation and growth of diphosphine ligands-protected Au NCs.

  19. Combined Quenching Mechanism of Anthracene Fluorescence by Cetylpyridinium Chloride in Sodium Dodecyl Sulfate Micelles.

    PubMed

    Soemo, Angela R; Pemberton, Jeanne E

    2014-03-01

    The Stern-Volmer quenching constant (KSV) for quenching of anthracene fluorescence in sodium dodecyl sulfate (SDS) micelles by pyridinium chloride has been reported previously to be 520 M(-1) based on steady state fluorescence measurements. However, such measurements cannot distinguish static versus dynamic contributions to the overall quenching. In the work reported here, the quenching dynamics of anthracene in SDS micelles by cetylpyridinium chloride (CPC), an analogue of pyridinium chloride, were investigated using both steady state and time resolved fluorescence quenching. Concurrent measurement of the decrease in fluorescence intensity and lifetime of anthracene provide a quantitative evaluation of collision induced (i.e. dynamic) versus complex formation (i.e. static) quenching of the anthracene fluorophore. The results reveal that a combined quenching mechanism is operative with approximately equal constants of 249 ± 6 M(-1) and 225 ± 12 M(-1) for dynamic and static quenching, respectively.

  20. Combined intrinsic and extrinsic neuronal mechanisms facilitate bridging axonal regeneration one year after spinal cord injury.

    PubMed

    Kadoya, Ken; Tsukada, Shingo; Lu, Paul; Coppola, Giovanni; Geschwind, Dan; Filbin, Marie T; Blesch, Armin; Tuszynski, Mark H

    2009-10-29

    Despite advances in promoting axonal regeneration after acute spinal cord injury (SCI), elicitation of bridging axon regeneration after chronic SCI remains a formidable challenge. We report that combinatorial therapies administered 6 weeks, and as long as 15 months, after SCI promote axonal regeneration into and beyond a midcervical lesion site. Provision of peripheral nerve conditioning lesions, grafts of marrow stromal cells, and establishment of NT-3 gradients supports bridging regeneration. Controls receiving partial components of the full combination fail to exhibit bridging. Notably, intraneuronal molecular mechanisms recruited by delayed therapies mirror those of acute injury, including activation of transcriptional activators and regeneration-associated genes. Collectively, these findings provide evidence that regeneration is achievable at unprecedented postinjury time points.

  1. [Apoptosis mechanism of taxol combined with resveratrol on human laryngeal carcinoma Hep-2 cells].

    PubMed

    Lu, Chen-Xin; Sun, Jing-Hui; Wu, Chun-Lian

    2016-02-01

    Laryngeal cancer is one of the most common malignant tumors in the respiratory tumors, and its incidence ranks second highest in the respiratory tumors. Resveratrol (Res) is a kind of polyphenols, which can inhibit nucleotides can inhibit the growth of liver cancer cells, gastric cancer cells, pancreatic cells and other tumor cells by inhibiting ribonucleotide reductase in the cells. Taxol (Tax) is a kind of secondary metabolites of Taxus chinensis, which has anti-tumor activity for breast cancer, cervical cancer, ovarian cancer and other tumors by inhibiting cellular microtubule depolymerization. But at present the effects of resveratrol combined with taxol on human laryngeal carcinoma cell strain Hep-2 and their underlying molecular mechanisms are rarely reported. After human laryngeal cancer cell Hep-2 cells were processed with resveratrol (Res) and taxol (Tax), CCK-8 assay was used to evaluate the effect of these two herbs on the proliferation of cancer cells; AO/PI staining and JC-1 were used to detect Hep-1 cells apoptosis; the expression of Bax, Bcl-2, PARP, TRIB3, and XIAP genes was detected by real time quantitative PCR; the activity of caspase-3 and caspase-8 was determined with quantitative fluorescence method. The experimental results showed that compared with Tax, Res medication alone, joint group significantly enhanced inhibition of Hep-2 cells activity, decreased the dosage of Tax, increased the expression of Bax and PARP, TRIB3, reduced the expression of the Bcl-2 and XIAP, and promoted the activity of caspase-3 and caspase-8. The test results showed that compared with the single medication, combined group could significantly increase the inhibitory effect on Hep-2 cells, significantly reduce Tax dosage, increase expressions of Bax, PARP, TRIB3, reduce expressions of Bcl-2, XIAP, and promote activity of caspase-3, caspase-8. This indicated apoptosis of human laryngeal carcinoma cell strain Hep-2 may be induced with Res, Tax, and the combination of

  2. The Molecular Mechanism of Action of the CR6261-Azichromycin Combination Found through Computational Analysis

    PubMed Central

    Cui, Wei; Wang, Kui; Ruan, Jishou; Qi, Zhi; Feng, Yi; Shao, Yiming; Tuszynski, Jack A.

    2012-01-01

    Background CR6261 was found in 2008 and F10 was found in 2009. In 2010 Friesen et al experimentally showed that Oseltamivir/Zanamivir may improve the therapeutic efficacy of CR6261. As a result, the use of CR6261 combined with a drug to provide an antibody-based therapy against all influenza A viruses was proposed. Although CR8020 may neutralize group 2 influenza viruses and FI6 may neutralize both group 1 and group 2 influenza viruses as determined in 2011, the insight of Friesen et al is still interesting. Here, we address the following questions: how to uncover the molecular mechanism of a drug, which improves the therapeutic efficacy of mAbs and how to find drugs that enable CR6261 (CR8020, F10) to become a universal mAb. Methods and Findings Using the 3D structures of 3 gbn, 3 gbm, 3 ztn, 3 ztj, 3 fku and 3 sdy, we separate the 3D structures of CR6261, F10, CR8020 and FI6, and the 3D structures of trimer HAs of H3N2 and H5N1. Based on the experimental result of Friesen et al, we have found many clues, which reveal the molecular mechanism of action for a drug and an HA-mAb complex. Conclusions Oseltamivir/Zanamivir may congruously improve the therapeutic efficacies of CR6261, F10, CR8020 and FI6 by providing an additional affinity to compensate for the loss of affinity between HA and mAb resulting from mutations. However, Oseltamivir or Zanamivir are not expected to generally widen the spectrum of these mAbs. In order to enhance CR6261, CR8020, or for F10 to become universal, we may select Azichromycin, Oseltamivir, or the combination of Azichromycin and Oseltamivir, respectively. PMID:22693576

  3. Impact of synchronous metastasis distribution on cancer specific survival in renal cell carcinoma after radical nephrectomy with tumor thrombectomy.

    PubMed

    Tilki, Derya; Hu, Brian; Nguyen, Hao G; Dall'Era, Marc A; Bertini, Roberto; Carballido, Joaquín A; Chandrasekar, Thenappan; Chromecki, Thomas; Ciancio, Gaetano; Daneshmand, Siamak; Gontero, Paolo; Gonzalez, Javier; Haferkamp, Axel; Hohenfellner, Markus; Huang, William C; Koppie, Theresa M; Linares, Estefania; Lorentz, C Adam; Mandel, Philipp; Martinez-Salamanca, Juan I; Master, Viraj A; Matloob, Rayan; McKiernan, James M; Mlynarczyk, Carrie M; Montorsi, Francesco; Novara, Giacomo; Pahernik, Sascha; Palou, Juan; Pruthi, Raj S; Ramaswamy, Krishna; Rodriguez Faba, Oscar; Russo, Paul; Shariat, Shahrokh F; Spahn, Martin; Terrone, Carlo; Thieu, William; Vergho, Daniel; Wallen, Eric M; Xylinas, Evanguelos; Zigeuner, Richard; Libertino, John A; Evans, Christopher P

    2015-02-01

    Metastatic renal cell carcinoma can be clinically diverse in terms of the pattern of metastatic disease and response to treatment. We studied the impact of metastasis and location on cancer specific survival. The records of 2,017 patients with renal cell cancer and tumor thrombus who underwent radical nephrectomy and tumor thrombectomy from 1971 to 2012 at 22 centers in the United States and Europe were analyzed. Number and location of synchronous metastases were compared with respect to patient cancer specific survival. Multivariable Cox regression models were used to quantify the impact of covariates. Lymph node metastasis (155) or distant metastasis (725) was present in 880 (44%) patients. Of the patients with distant disease 385 (53%) had an isolated metastasis. The 5-year cancer specific survival was 51.3% (95% CI 48.6-53.9) for the entire group. On univariable analysis patients with isolated lymph node metastasis had a significantly worse cancer specific survival than those with a solitary distant metastasis. The location of distant metastasis did not have any significant effect on cancer specific survival. On multivariable analysis the presence of lymph node metastasis, isolated distant metastasis and multiple distant metastases were independently associated with cancer specific survival. Moreover higher tumor thrombus level, papillary histology and the use of postoperative systemic therapy were independently associated with worse cancer specific survival. In our multi-institutional series of patients with renal cell cancer who underwent radical nephrectomy and tumor thrombectomy, almost half of the patients had synchronous lymph node or distant organ metastasis. Survival was superior in patients with solitary distant metastasis compared to isolated lymph node disease. Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  4. The Use of the 'Preclosure' Technique for Antegrade Aspiration Thrombectomy with Large Catheters in Acute Limb Ischemia

    SciTech Connect

    Funke, C. Pfiffner, R.; Husmann, M.; Pfammatter, T.

    2013-04-15

    This study was designed to assess retrospectively short- and mid-term outcomes of the use of a suture-mediated closure device to close the antegrade access in patients undergoing percutaneous aspiration thrombectomy with large catheters for acute leg ischemia. Between November 2005 and February 2010, a suture-mediated active closure system (ProGlide{sup Registered-Sign} 6F, Abbott) was placed before arterial sheath (mean 9 F, range 6-12 F) introduction in 101 patients (74 men, 73 %, mean age 70.1 {+-} 12.6 years standard deviation). Data regarding mortality, complications, and factors contributing to vascular complications at the access site was collected for 6 month after the intervention to detect device-related problems. As a coincidence, 77 patients had follow-up visits for a duplex ultrasound. There were a total of 19 vascular complications (19 %) at the puncture site, all of which were of hemorrhagic nature and none of which consisted of vessel occlusion. Two major outcome complications (2 %) occurred. A retroperitoneal hematoma and a serious inguinal bleeding required additive treatment and did not result in permanent sequelae. Nine cases involved death of which eight were not attributable to the closure and one remained unclear. Successful closure was achieved in 95 patients (94 %); additional manual compression was sufficient in the majority of the remaining patients. Numerous factors contributing to vascular complications were encountered. With acceptable short- and mid-term outcomes, the 'preclose' technique can be a reliable option for the closure of a large antegrade femoral access even for patients at a high risk of vascular complications, such as those undergoing aspiration thrombectomy.

  5. Experience with A Direct Aspiration First Pass Technique (ADAPT) for Thrombectomy in Distal Cerebral Artery Occlusions Causing Acute Ischemic Stroke.

    PubMed

    Vargas, Jan; Spiotta, Alex M; Fargen, Kyle; Turner, Raymond D; Chaudry, Imran; Turk, Aquilla

    2017-03-01

    Thromboembolic occlusion of distal branches in anterior and posterior circulation may produce severe clinical deficits. A Direct Aspiration at first Pass Technique (ADAPT) is a simple, fast method for achieving good angiographic and clinical outcomes using large-bore catheters in large vessel occlusions. We present our results using ADAPT with distal cerebral artery occlusions. ADAPT was used to treat 35 patients (14 women, 21 men; average age 65.5 years ± 12.6) with acute ischemic stroke with thrombus in the distal middle cerebral artery, anterior cerebral artery, or posterior cerebral artery. Patients presented with a mean National Institutes of Health Stroke Scale score of 14.1 ± 6.9; 15 patients received intravenous tissue plasminogen activator. Mean time from onset to puncture was 7.1 hours ± 5.1. Of patients, 28 (80%) presented with isolated M2 segment occlusions, 1 (2.9%) presented with isolated A3 segment occlusion, and 6 (17.1%) presented with tandem occlusions. Mean time to recanalization was 35.7 minutes ± 26.4. A thrombolysis in cerebral infarction grade 2B or better was achieved in 34 patients (97.1%), with 15 achieving a thrombolysis in cerebral infarction 3. Aspiration alone was successful in 26 cases (77.1%), whereas 7 (20%) required additional techniques. A 90-day modified Rankin Scale score was available in 32 patients; 59.4% had a 90-day score of 0-2. No patients had a modified Rankin Scale score of 6. Acute distal anterior circulation thromboembolic occlusions may be treated safely with intraarterial thrombectomy. Prior studies have demonstrated the success of ADAPT in proximal large vessel occlusions. This series suggests that ADAPT is an effective, safe method for performing thrombectomy in distal branches of anterior and posterior circulation. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Stretchable Silver Nanowire Microelectrodes for Combined Mechanical and Electrical Stimulation of Cells.

    PubMed

    Hosseini, Vahid; Gantenbein, Silvan; Avalos Vizcarra, Ima; Schoen, Ingmar; Vogel, Viola

    2016-08-01

    The use of stretchable electrodes interfaced with the human body has enabled a new frontier in biomedical engineering, and the miniaturization of such electrodes can allow for a more precise spatial control to monitor or stimulate tissues. The understanding of the response of cells or tissues to combined electromechanical stimulation, as made possible by stretchable electrodes, is essential to improve medical devices and therapies. Cheap to produce and easy to use platforms for in vitro cell studies are thus urgently needed. This study reports the successful implementation of silver nanowires (AgNWs) into an integrated miniaturized electromechanical stimulator, which is compatible with cell culture. The innovative steps include a lithography-based lift-off method to micropattern AgNWs onto an elastic silicone membrane. These stretchable microelectrodes are then integrated into a microfluidic device for cell culture, which enables the synchronous electromechanical stimulation of cells. In a proof-of-concept study, it is furthermore shown that fibroblasts respond uniquely to mechanical stretching, electrical stimulation, and combined electromechanical stimulations in terms of cell alignment and morphology, as well as by producing the extracellular matrix protein collagen. This proof-of-concept study illustrates the functionality and usability of these stretchable AgNWs microelectrodes for either basic research or future biomedical applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Neural mechanisms of attention become more specialised during infancy: Insights from combined eye tracking and EEG.

    PubMed

    Kulke, Louisa; Atkinson, Janette; Braddick, Oliver

    2017-03-01

    The Fixation Shift Paradigm (FSP) measures infants' ability to shift gaze from a central fixation stimulus to a peripheral target (e.g. Hood & Atkinson, 1993: Infant Behavior and Development, 16(4), 405-422). Cortical maturation has been suggested as crucial for the developing ability to shift attention. This study investigated the development of neural mechanisms by combining EEG with simultaneous eye tracking during FSP testing, in typically developing infants aged between 1 and 8 months. The most prominent neural response was a frontal positivity which occurred only in the hemisphere contralateral to the target in the youngest infants but became more ipsilateral with age. This changing lateralisation was associated with improving ability to shift attention (decreasing saccade latencies and fewer 'sticky fixations'-failures to disengage attention from the central target). These findings suggest that the lateralisation of neural responses develops during infancy, possibly due to developing intracortical connections, allowing infants to shift attention more efficiently. Successful use of combined simultaneous remote eye tracking and EEG to measure infant attention shifts. Neural responses involved in attention shifts change in the first year of life. The lateralisation of EEG responses changes with age in the first year of life. Frontal cortex is involved in attention shifts from around 2 months of age. © 2016 Wiley Periodicals, Inc.

  8. Modulation of oligodendrocyte differentiation and maturation by combined biochemical and mechanical cues

    PubMed Central

    Lourenço, Tânia; Paes de Faria, Joana; Bippes, Christian A.; Maia, João; Lopes-da-Silva, José A.; Relvas, João B.; Grãos, Mário

    2016-01-01

    Extracellular matrix (ECM) proteins play a key role during oligodendrogenesis. While fibronectin (FN) is involved in the maintenance and proliferation of oligodendrocyte progenitor cells (OPCs), merosin (MN) promotes differentiation into oligodendrocytes (OLs). Mechanical properties of the ECM also seem to affect OL differentiation, hence this study aimed to clarify the impact of combined biophysical and biochemical elements during oligodendrocyte differentiation and maturation using synthetic elastic polymeric ECM-like substrates. CG-4 cells presented OPC- or OL-like morphology in response to brain-compliant substrates functionalised with FN or MN, respectively. The expression of the differentiation and maturation markers myelin basic protein — MBP — and proteolipid protein — PLP — (respectively) by primary rat oligodendrocytes was enhanced in presence of MN, but only on brain-compliant conditions, considering the distribution (MBP) or amount (PLP) of the protein. It was also observed that maturation of OLs was attained earlier (by assessing PLP expression) by cells differentiated on MN-functionalised brain-compliant substrates than on standard culture conditions. Moreover, the combination of MN and substrate compliance enhanced the maturation and morphological complexity of OLs. Considering the distinct degrees of stiffness tested ranging within those of the central nervous system, our results indicate that 6.5 kPa is the most suitable rigidity for oligodendrocyte differentiation. PMID:26879561

  9. Growth inhibitive effect of betulinic acid combined with tripterine on MSB-1 cells and its mechanism.

    PubMed

    An, N; Li, H Y; Zhang, X M

    2015-12-01

    Marek's disease (MD), a highly infectious lymphoproliferative disease in chickens, is caused by a cell-associated oncogenic herpesvirus, Marek's disease virus (MDV). MSB-1 is a MD-derived lymphoblastoid cell line and can induce tumors when inoculated into susceptible chickens. Betulinic acid, which is present as one of the major effective components in many traditional Chinese medicines, has recently been reported to inhibit growth of cancer cells and employed as a potential anticancer agent. Tripterine, a major active compound extracted from the Chinese herb Tripterygium wilfordii Hook F, has now also shown anti-tumor activities in various cancers. The aim of this study was to investigate the synergistic growth-inhibitive effect of betulinic acid combined with tripterine on MSB-1 cells and its mechanism. Viability of MSB-1 cells was assessed by 3-(4,5-dimethylthiazol-2-y1)-2,5-diphenyltetrazolium bromide (MTT) method. Cell apoptotic analysis was performed by fluorescence detection. NF-κB transcription activity was detected by measuring luciferase activity. Western blotting was used to analyze the expression of p65, IκB and Meq. Our results showed that the proliferation in the combination group was significantly decreased as compared with that of monotherapy using betulinic acid or tripterine, accompanied by an induction of apoptosis, inhibition of NF-κB transcriptional activity and its targeting oncogenic gene Meq. The results suggest that the combination of betulinic acid and tripterine at lower concentration may produce a synergistic inhibitive effect on MSB-1 cells that warrants further investigation for its potential clinical applications.

  10. Bacterial radiosensitization by using radiation processing in combination with essential oil: Mechanism of action

    NASA Astrophysics Data System (ADS)

    Lacroix, Monique; Caillet, Stéphane; Shareck, Francois

    2009-07-01

    Spice extracts under the form of essential oils were tested for their efficiency to increase the relative radiosensitivity of Listeria monocytogenes and Escherichia coli O157H7 in culture media. The two pathogens were treated by gamma-irradiation alone or in combination with oregano essential oil to evaluate their mechanism of action. The membrane murein composition, and the intracellular and extracellular concentration of ATP was determined. The bacterial strains were treated with two irradiation doses: 1.2 kGy to induce cell damage and 3.5 kGy to cause cell death for L. monocytogenes. A dose of 0.4 kGy to induce cell damages, 1.1 kGy to obtain viable but nonculturable (VBNC) state and 1.3 kGy to obtain a lethal dose was also applied on E. coli O157H7. Oregano essential oil was used at 0.020% and 0.025% (w/v), which is the minimum inhibitory concentration (MIC) for L. monocytogenes. For E. coli O157H7, a concentration of 0.006% and 0.025% (w/v) which is the minimum inhibitory concentration was applied. The use of essential oils in combination with irradiation has permitted an increase of the bacterial radiosensitization by more than 3.1 times. All treatments had also a significant effect ( p⩽0.05) on the murein composition, although some muropeptides did not seem to be affected by the treatment. Each treatment influenced differently the relative percentage and number of muropeptides. There was a significant ( p⩽0.05) correlation between the reduction of intracellular ATP and increase in extracellular ATP following treatment of the cells with oregano oil. The reduction of intracellular ATP was even more important when essential oil was combined with irradiation, but irradiation of L. monocytogenes alone induced a significant decrease ( p⩽0.05) of the internal ATP without affecting the external ATP.

  11. Combined use of nitrogen and coatings to improve the quality of mechanically harvested Manzanilla olives.

    PubMed

    Ramírez, Eva; Sánchez, Antonio H; Romero, Concepción; Brenes, Manuel

    2015-03-15

    The combined effect of an edible coating and a nitrogen atmosphere on the quality of Manzanilla olives mechanically harvested and processed as Spanish-style green olives was assessed. The percentage of olives free of any brown spots ranged between 35-50%, 10-25% and 50-65% for fruit directly processed, storage under nitrogen and coated and storage under nitrogen respectively. Moreover, olives stored in the open air developed brown spots due to the oxidation of oleuropein. By contrast, the anoxic conditions prevented oleuropein from undergoing enzymatic oxidation but not from its enzymatic hydrolysis. Hence, the phenolic derivative HyEDA was formed in olives stored under nitrogen, and this substance was rapidly oxidized in the open air to give rise to brown spots although to a lesser extent in the coated fruit. Therefore, the postharvest storage of coated olives under nitrogen can be a good method to prevent bruise damage in mechanically harvested fruit. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Subchromoplast sequestration of carotenoids affects regulatory mechanisms in tomato lines expressing different carotenoid gene combinations.

    PubMed

    Nogueira, Marilise; Mora, Leticia; Enfissi, Eugenia M A; Bramley, Peter M; Fraser, Paul D

    2013-11-01

    Metabolic engineering of the carotenoid pathway in recent years has successfully enhanced the carotenoid contents of crop plants. It is now clear that only increasing biosynthesis is restrictive, as mechanisms to sequestrate these increased levels in the cell or organelle should be exploited. In this study, biosynthetic pathway genes were overexpressed in tomato (Solanum lycopersicum) lines and the effects on carotenoid formation and sequestration revealed. The bacterial Crt carotenogenic genes, independently or in combination, and their zygosity affect the production of carotenoids. Transcription of the pathway genes was perturbed, whereby the tissue specificity of transcripts was altered. Changes in the steady state levels of metabolites in unrelated sectors of metabolism were found. Of particular interest was a concurrent increase of the plastid-localized lipid monogalactodiacylglycerol with carotenoids along with membranous subcellular structures. The carotenoids, proteins, and lipids in the subchromoplast fractions of the transgenic tomato fruit with increased carotenoid content suggest that cellular structures can adapt to facilitate the sequestration of the newly formed products. Moreover, phytoene, the precursor of the pathway, was identified in the plastoglobule, whereas the biosynthetic enzymes were in the membranes. The implications of these findings with respect to novel pathway regulation mechanisms are discussed.

  13. [Mechanism of action of combined extremely weak magnetic field on aqueous solution of amino acid].

    PubMed

    Zhadin, M N; Bakharev, B V; Bobkova, N V

    2014-01-01

    The fundamental physical mechanisms of resonance action of an extremely weak (40 nT) alternating magnetic field at the cyclotron frequency combined with a weak (40 μT) static magnetic field, on living systems are analyzed in the present work. The experimental effects of such sort of magnetic fields were described in different papers: the very narrow resonant peaks in electrical conductivity of the aqueous solutions in the in vitro experiments and the biomedical in vivo effects on living animals of magnetic fields with frequencies tuned to some amino acids. The existing experimental in vitro data had a good repeatability in different laboratories and countries. Unfortunately, for free ions such sort of effects are absolutely impossible because the dimensions of an ion rotation radius should be measured by meters at room temperature and at very low static magnetic fields used in all the above experiments. Even for bound ions these effects should be also absolutely impossible from the positions of classic physics because of rather high viscosity of biological liquid media (blood plasma, cerebrospinal liquid, cytoplasm). Only modern quantum electrodynamics of condensed media opens the new ways for solving these problems. The proposed article is devoted to analysis of quantum mechanisms of these effects.

  14. Comprehensive mechanical characterization of PLA fabric combined with PCL to form a composite structure vascular graft.

    PubMed

    Li, Chaojing; Wang, Fujun; Douglas, Graeham; Zhang, Ze; Guidoin, Robert; Wang, Lu

    2017-05-01

    Vascular grafts made by tissue engineering processes are prone to buckling and twisting, which can impede blood flow and lead to collapse of the vessel. These vascular conduits may suffer not only from insufficient tensile strength, but also from vulnerabilities related to compression, torsion, and pulsatile pressurization. Aiming to develop a tissue engineering-inspired blood conduit, composite vascular graft (cVG) prototypes were created by combining a flexible polylactic acid (PLA) knitted fabric with a soft polycaprolactone (PCL) matrix. The graft is to be populated in-situ with cellular migration and proliferation into the device. Comprehensive characterizations probed the relationship between structure and mechanical properties of the different cVG prototypes. The composite grafts exhibited major improvements in mechanical characteristics compared to single-material devices, with particular improvement in compression and torsional resistance. A commercial expanded polytetrafluoroethylene (ePTFE) vascular graft was used as a control against the proposed composite vascular grafts. CVG devices showed high tensile strength, high bursting strength, and improved suture retention. Compression, elastic recovery, and compliance were similar to those for the ePTFE graft. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Combining ibuprofen sodium with cellulosic polymers: a deep dive into mechanisms of prolonged supersaturation.

    PubMed

    Terebetski, Jenna L; Michniak-Kohn, Bozena

    2014-11-20

    The combination of a highly soluble salt form of a drug with a polymeric precipitation inhibitor has the potential to prolong drug supersaturation even following salt disproportionation. In this study, dissolution profiles of ibuprofen sodium in the presence of various cellulosic polymers, including hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), and hydroxypropyl cellulose (HPC), were examined in order to assess degree and duration of supersaturation. In addition, the roles that the polymers played in altering drug solubility, media viscosity, physical form, and particle morphology were also assessed. A deep dive into the mechanisms of supersaturation revealed that intermolecular hydrogen bonding between ibuprofen and HPMC was driving supersaturation through nucleation inhibition and crystal growth modification. Polymer viscosity was proposed as the primary factor prolonging supersaturation of ibuprofen in the presence of MC, while mechanisms other than hydrogen bonding were likely to be attributed to supersaturation with the most hydrophobic polymer evaluated, HPC. Overall, the study suggested that induction of intermolecular interactions between ibuprofen and HPMC were more effective at inhibiting nucleation and maintaining prolonged supersaturation than physical modulation of solution properties, such as viscosity. Copyright © 2014. Published by Elsevier B.V.

  16. A numerical study of combined use of two biocontrol agents with different biocontrol mechanisms in controlling foliar pathogens.

    PubMed

    Xu, X-M; Jeffries, P; Pautasso, M; Jeger, M J

    2011-09-01

    Effective use of biocontrol agents is an important component of sustainable agriculture. A previous numerical study of a generic model showed that biocontrol efficacy was greatest for a single biocontrol agent (BCA) combining competition with mycoparasitism or antibiosis. This study uses the same mathematical model to investigate whether the biocontrol efficacy of combined use of two BCAs with different biocontrol mechanisms is greater than that of a single BCA with either or both of the two mechanisms, assuming that two BCAs occupy the same host tissue as the pathogen. Within the parameter values considered, a BCA with two biocontrol mechanisms always outperformed the combined use of two BCAs with a single but different biocontrol mechanism. Similarly, combined use of two BCAs with a single but different biocontrol mechanism is shown to be far less effective than that of a single BCA with both mechanisms. Disease suppression from combined use of two BCAs was very similar to that achieved by the more efficacious one. As expected, a higher BCA introduction rate led to increased disease suppression. Incorporation of interactions between two BCAs did not greatly affect the disease dynamics except when a mycoparasitic and, to a lesser extent, an antibiotic-producing BCA was involved. Increasing the competitiveness of a mycoparasitic BCA over a BCA whose biocontrol mechanism is either competition or antibiosis may lead to improved biocontrol initially and reduced fluctuations in disease dynamics. The present study suggests that, under the model assumptions, combined use of two BCAs with different biocontrol mechanisms in most cases only results in control efficacies similar to using the more efficacious one alone. These predictions are consistent with published experimental results, suggesting that combined use of BCAs should not be recommended without clear understanding of their main biocontrol mechanisms and relative competitiveness, and experimental evaluation.

  17. Combined Effects of UV Exposure Duration and Mechanical Abrasion on Microplastic Fragmentation by Polymer Type.

    PubMed

    Song, Young Kyoung; Hong, Sang Hee; Jang, Mi; Han, Gi Myung; Jung, Seung Won; Shim, Won Joon

    2017-03-28

    It is important to understand the fragmentation processes and mechanisms of plastic litter to predict microplastic production in the marine environment. In this study, accelerated weathering experiments were performed in the laboratory, with ultraviolet (UV) exposure for up to 12 months followed by mechanical abrasion (MA) with sand for 2 months. Fragmentation of low-density polyethylene (PE), polypropylene (PP), and expanded polystyrene (EPS) was evaluated under conditions that simulated a beach environment. PE and PP were minimally fragmented by MA without photooxidation by UV (8.7 ± 2.5 and 10.7 ± 0.7 particles/pellet, respectively). The rate of fragmentation by UV exposure duration increased more for PP than PE. A 12-month UV exposure and 2-month MA of PP and PE produced 6084 ± 1061 and 20 ± 8.3 particles/pellet, respectively. EPS pellets were susceptible to MA alone (4220 ± 33 particles/pellet), while the combination of 6 months of UV exposure followed by 2 months of MA produced 12,152 ± 3276 particles/pellet. The number of fragmented polymer particles produced by UV exposure and mechanical abrasion increased with decreasing size in all polymer types. The size-normalized abundance of the fragmented PE, PP, and EPS particles according to particle size after UV exposure and MA was predictable. Up to 76.5% of the initial EPS volume was unaccounted for in the final volume of pellet produced particle fragments, indicating that a large proportion of the particles had fragmented into undetectable submicron particles.

  18. Combined exposure to big endothelin-1 and mechanical loading in bovine sternal cores promotes osteogenesis.

    PubMed

    Meyer, Luisa A; Johnson, Michael G; Cullen, Diane M; Vivanco, Juan F; Blank, Robert D; Ploeg, Heidi-Lynn; Smith, Everett L

    2016-04-01

    , 19 and 23. The data suggest that combined exposure to big ET1 and mechanical loading results in increased osteogenesis as measured in biomechanical, histomorphometric and biochemical responses.

  19. Incidence and mechanisms of resistance to the combination of amoxicillin and clavulanic acid in Escherichia coli.

    PubMed Central

    Stapleton, P; Wu, P J; King, A; Shannon, K; French, G; Phillips, I

    1995-01-01

    Among Escherichia coli organisms isolated at St. Thomas's Hospital during the years 1990 to 1994, the frequency of resistance to amoxicillin-clavulanic acid (tested by disk diffusion in a ratio of 2:1) remained constant at about 5% of patient isolates (10 to 15% of the 41 to 45% that were amoxicillin resistant). Mechanisms of increased resistance were determined for 72 consecutively collected such amoxicillin-clavulanic acid-resistant isolates. MICs of the combination were 16-8 micrograms/ml for 51 (71%) of these and > or = 32-16 micrograms/ml for the remainder. The predominant mechanism was hyperproduction of enzymes isoelectrically cofocusing with TEM-1 (beta-lactamase activities, > 200 nmol of nitrocefin hydrolyzed per min per mg of protein) which was found in 44 isolates (61%); two isolates produced smaller amounts (approximately 150 nmol/min/mg) of such enzymes, and two isolates hyperproduced enzymes cofocusing with TEM-2. Eleven isolates produced enzymes cofocusing with OXA-1 beta-lactamase, which has previously been associated with resistance to amoxicillin-clavulanic acid. Ten isolates produced increased amounts of chromosomal beta-lactamase, and four of these additionally produced TEM-1 or TEM-2. Three isolates produced inhibitor-resistant TEM-group enzymes. In one of the enzymes (pI, 5.4), the amino acid sequence change was Met-67-->Val, and thus the enzyme is identical to TEM-34. Another (pI, 5.4) had the substitution Met-67-->Ile and is identical to IRT-I67, which we propose now be given the designation TEM-40. The third (pI, 5.2) had the substitution Arg-241-->Thr; this enzyme has not been reported previously and should be called TEM-41. The rarity and diversity of inhibitor-resistant TEM-group enzymes suggest that they are the result of spontaneous mutations that have not yet spread. PMID:8585729

  20. Opioid Mechanism Involvement in the Synergism Produced by the Combination of Diclofenac and Caffeine in the Formalin Model

    PubMed Central

    Flores-Ramos, José María; Díaz-Reval, M. Irene

    2013-01-01

    Analgesics can be administered in combination with caffeine for improved analgesic effectiveness in a process known as synergism. The mechanisms by which these combinations produce synergism are not yet fully understood. The aim of this study was to analyze whether the administration of diclofenac combined with caffeine produced antinociceptive synergism and whether opioid mechanisms played a role in this event. The formalin model was used to evaluate the antinociception produced by the oral administration of diclofenac, caffeine, or their combination. Opioid involvement was analyzed through intracerebroventricular (i.c.v.) administration of naloxone followed by the oral administration of the study drugs. Diclofenac presented a dose-dependent effect, with a mean effective dose (ED50) of 6.7 mg/kg. Caffeine presented an analgesic effect with a 17–36% range. The combination of subeffective doses of each of the two drugs presented the greatest synergism with an effect of 57.7 ± 5.6%. The maximal antinociceptive effect was obtained with the combination of 10.0 mg/kg diclofenac and 1.0 mg/kg of caffeine, with an effect of 76.7 ± 5.6%. The i.c.v. administration of naloxone inhibited the effect of diclofenac, both separately and combined. In conclusion, caffeine produces antinociceptive synergism when administered in combination with diclofenac, and this synergism is partially mediated by opioid mechanisms at the central level. PMID:27335871

  1. Mechanical behavior of twinned SiC nanowires under combined tension-torsion and compression-torsion strain

    SciTech Connect

    Li, Zhijie; Wang, Shengjie; Wang, Zhiguo; Zu, Xiaotao T.; Gao, Fei; Weber, William J.

    2010-07-01

    The mechanical behavior of twinned silicon carbide (SiC) nanowires under combined tension-torsion and compression-torsion is investigated using molecular dynamics simulations with an empirical potential. The simulation results show that both the tensile failure stress and buckling stress decrease under combined tension-torsional and combined compression-torsional strain, and they decrease with increasing torsional rate under combined loading. The torsion rate has no effect on the elastic properties of the twinned SiC nanowires. The collapse of the twinned nanowires takes place in a twin stacking fault of the nanowires.

  2. Hydrous Ringwoodite: Clarifying Defect Mechanisms Through Combined Single-Crystal Refinement, Compressibility, and IR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Panero, W. R.; Smyth, J. R.; Jacobsen, S. D.; Frost, D. J.; Reaman, D. M.; Pigott, J. S.; Thomas, S.; Liu, Z.

    2009-12-01

    Incorporation of hydrogen into mantle silicates reduces bulk density and compressibility by varying amounts through associated defects. As the stiffest of the olivine polymorphs, ringwoodite should experience the greatest effects of hydration. We have synthesized Mg ringwoodite (γ-Mg2SiO4) with 2.6 wt% H2O at 20 GPa and 1250°C in the 5000 ton multi-anvil press at Bayerisches Geoinstitut and refined the crystal structure at ambient conditions from single-crystal X-ray diffraction data. The unit cell length is 8.0829(3) Å. The hydration mechanism is principally by octahedral cation vacancy with possible minor tetrahedral vacancy at a ratio of ~7:1. To further clarify the defect mechanism, we report low-temperature, ambient-pressure FTIR together with room temperature compression in a quasi-hydrostatic neon pressure medium to 23 GPa. FTIR spectra of this sample as well as one with about half the water content show three primary overlapping OH stretching bands at 2534, 3125, and 3622 cm-1 at ambient pressure and 300 K. Cooling to 11 K shows just 3% reduction of the width of the main 3125 cm-1 OH band, whereas the peak width reduction was recovered upon heating to room temperature. The sample with the lower water content shows splitting of the primary 3125 cm-1 peak, to 3089 and 3263 cm-1 at temperatures below 120 K. We interpret these results to indicate that the high water storage capacity of ringwoodite results from a combination of multiple bonding sites and loosely bound hydrogen dominated by cation vacancies. The 300 K isothermal bulk modulus (K0) and its pressure derivative (K’=dK0/dP) are 160.7(1.1) GPa and 5.0(2) respectively. Compared with nominally anhydrous ringwoodite, we observe a 12% decrease in the bulk modulus and a measurable increase in K’. The data indicate some evidence οf a change in compression mechanism at ~15 GPa, possibly resulting from a shift from initial compression of vacancies to more uniform compression of the structure

  3. Combined photosynthesis and mechanical aeration for nitrification in dairy waste stabilisation ponds.

    PubMed

    Sukias, J P S; Craggs, R J; Tanner, C C; Davies-Colley, R J; Nagels, J W

    2003-01-01

    New Zealand has 16,500 dairy farms (avg. 220 cows), with cows kept on pasture throughout the year. During the 9-month dairy season, the cows are milked twice a day (averaging 2.5-3 h per day in the dairy parlour). Urine and faecal wastes deposited in the dairy parlour are washed away with high pressure hoses, using large volumes of water. A common method of treatment is in simple two-pond (anaerobic/facultative) lagoon systems, which remove about 95% of suspended solids and BOD5, but only 75% of total-N prior to discharge. High concentrations of ammoniacal-N in the effluent can cause toxicity to aquatic organisms in receiving waters. Mechanical aeration of the second (facultative) lagoon to promote nitrification improves effluent quality by reducing oxygen demand and potential ammonia toxicity to streamlife. Mechanical aeration however is associated with considerable mixing, which may prevent algae from optimising photosynthesis in the facultative lagoon. A series of experiments was undertaken which tested the efficiency of mechanical aeration and then attempted to combine it with daytime algal oxygen production in order to maximise ammonia conversion to nitrate, while minimising costs to the farmer. An experimental facility was developed by dividing a large facultative lagoon into two, producing a matched pair of lagoons, operated in parallel with influent flow split equally. Over successive dairy seasons, various aeration regimes were compared. Continuous aeration promoted nearly complete nitrification of the ammoniacal-N (99% removal), and effluent BOD was approximately halved. However the continuous mixing reduced algal biomass, and thus daytime algal photosynthesis. Night-only aeration permitted greater algal photosynthesis to occur, as well as halving electrical power consumption. Ammoniacal-N removal reduced to 90% (10 g m(-3) remaining in the effluent), while BOD removal was also lower than in the continuously aerated lagoon (59 and 69% respectively

  4. The neural dynamic mechanisms of asymmetric switch costs in a combined Stroop-task-switching paradigm

    PubMed Central

    Wu, Shanshan; Hitchman, Glenn; Tan, Jinfeng; Zhao, Yuanfang; Tang, Dandan; Wang, Lijun; Chen, Antao

    2015-01-01

    Switch costs have been constantly found asymmetrical when switching between two tasks of unequal dominance. We used a combined Stroop-task-switching paradigm and recorded electroencephalographic (EEG) signals to explore the neural mechanism underlying the phenomenon of asymmetrical switch costs. The results revealed that a fronto-central N2 component demonstrated greater negativity in word switch (cW) trials relative to word repeat (wW) trials, and both First P3 and P3b components over the parieto-central region exhibited greater positivity in color switch (wC) trials relative to color repeat (cC) trials, whereas a contrasting switch-related fronto-central SP effect was found to have an opposite pattern for each task. Moreover, the time-frequency analysis showed a right-frontal lower alpha band (9-11 Hz) modulation in the word task, whereas a fronto-central upper alpha band (11-13 Hz) modulation was exclusively found in the color task. These results provide evidence for dissociable neural processes, which are related to inhibitory control and endogenous control, contributing to the generation of asymmetrical switch costs. PMID:25989933

  5. Mechanism-based corrector combination restores ΔF508-CFTR folding and function

    PubMed Central

    Okiyoneda, Tsukasa; Veit, Guido; Dekkers, Johanna F.; Bagdany, Miklos; Soya, Naoto; Xu, Haijin; Roldan, Ariel; Verkman, Alan S.; Kurth, Mark; Simon, Agnes; Hegedus, Tamas; Beekman, Jeffrey M.; Lukacs, Gergely L.

    2013-01-01

    The most common cystic fibrosis (CF) mutation, ΔF508 in the nucleotide binding domain-1 (NBD1), impairs CFTR coupled-domain folding, plasma membrane (PM) expression, function and stability. VX-809, a promising investigational corrector of ΔF508-CFTR misprocessing, has limited clinical benefit and incompletely understood mechanism, hampering drug development. Based on the effect of second site suppressor mutations, robust ΔF508-CFTR correction likely requires stabilization of NBD1 and the membrane spanning domains (MSDs)-NBD1 interface, both established primary conformational defects. Here, we elucidated the molecular targets of available correctors; class-I stabilizes the NBD1-MSD1/2 interface, class-II targets NBD2, and only chemical chaperones, surrogates of class-III correctors, stabilize the human ΔF508-NBD1. While VX-809 can correct missense mutations primarily destabilizing the NBD1-MSD1/2 interface, functional PM expression of ΔF508-CFTR also requires compounds that counteract the NBD1 and NBD2 stability defects in CF bronchial epithelial cells and intestinal organoids. Thus, structure-guided corrector combination represents an effective approach for CF therapy. PMID:23666117

  6. Enhancing combined biological nitrogen and phosphorus removal from wastewater by applying mechanically disintegrated excess sludge.

    PubMed

    Zubrowska-Sudol, Monika; Walczak, Justyna

    2015-06-01

    The goal of the study was to evaluate the possibility of applying disintegrated excess sludge as a source of organic carbon to enhance biological nitrogen and phosphorus removal. The experiment, performed in a sequencing batch reactor, consisted of two two-month series, without and with applying mechanically disintegrated excess sludge, respectively. The effects on carbon, nitrogen and phosphorus removal were observed. It was shown that the method allows enhancement of combined nitrogen and phosphorus removal. After using disintegrated sludge, denitrification effectiveness increased from 49.2 ± 6.8% to 76.2 ± 2.3%, which resulted in a decline in the NOx-N concentration in the effluent from the SBR by an average of 21.4 mg NOx-N/L. Effectiveness of biological phosphorus removal increased from 28.1 ± 11.3% to 96.2 ± 2.5%, thus resulting in a drop in the [Formula: see text] concentration in the effluent by, on average, 6.05 mg PO4(3-)-P/L. The application of disintegrated sludge did not deteriorate effluent quality in terms of COD and NH4(+)-N. The concentration of NH4(+)-N in both series averaged 0.16 ± 0.11 mg NH4(+)-N/L, and the concentration of COD was 15.36 ± 3.54 mg O2/L. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Heat flux reduction mechanism induced by a combinational opposing jet and cavity concept in supersonic flows

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Jiang, Yan-ping; Yan, Li; Liu, Jun

    2016-04-01

    The thermal protection on the surface of hypersonic vehicles attracts an increasing attention worldwide, especially when the vehicle enters the atmosphere at high speed. In the current study, the Reynolds-averaged Navier-Stokes (RANS) equations coupled with the Menter's shear stress transport (SST) model have been employed to investigate the heat flux reduction mechanism induced by the variations of the cavity configuration, the jet pressure ratio and the injectant molecular weight in the combinational opposing jet and cavity concept. The length of the cavity is set to be 6 mm, 8 mm and 10 mm in order to make sure that the cavity configuration is the "open" cavity, and the jet pressure ratio is set to be 0.4, 0.6 and 0.8 in order to make sure that the flow field is steady. The injectant is set to be nitrogen and helium. The obtained results show that the aft angle of the cavity only has a slight impact on the heat flux reduction, and the heat flux peak decreases with the decrease of the length of the cavity. The design of the thermal protection system for the hypersonic blunt body is a multi-objective design exploration problem, and the heat flux distribution depends on the jet pressure ratio, the aft wall of the cavity and the injectant molecular weight. The heat flux peak decreases with the increase of the jet pressure ratio when the aft angle of the cavity is large enough, and this value is 45°.

  8. Potential of combining mechanical and physicochemical municipal wastewater pre-treatment with direct membrane filtration.

    PubMed

    Hey, Tobias; Väänänen, Janne; Heinen, Nicolas; la Cour Jansen, Jes; Jönsson, Karin

    2017-01-01

    At a full-scale wastewater treatment plant, raw municipal wastewater from the sand trap outlet was mechanically and physicochemically pre-treated before microfiltration (MF) in a large pilot-scale study. MF was performed using a low transmembrane pressure (0.03 bar) without backflushing for up to 159 h (∼6.6 d). Pre-filtration ensured stable MF operation compared with the direct application of raw wastewater on the membrane. The combination of physicochemical pre-treatment, such as coagulation, flocculation, and microsieving, with MF meets the European and Swedish discharge limits for small- and medium-sized wastewater treatment plants (WWTPs). The specific electricity footprint was 0.3-0.4 kWh·m(-3), which is an improvement compared to the median footprint of 0.75 kWh·m(-3) found in 105 traditional Swedish WWTPs with sizes of 1500-10,000 person equivalents. Furthermore, the biological treatment step can be omitted, and the risk of releasing greenhouse gases was eliminated. The investigated wastewater treatment process required less space than conventional wastewater treatment processes, and more carbon was made available for biogas production.

  9. Electrostatic vibration energy harvester with combined effect of electrical nonlinearities and mechanical impact

    NASA Astrophysics Data System (ADS)

    Basset, P.; Galayko, D.; Cottone, F.; Guillemet, R.; Blokhina, E.; Marty, F.; Bourouina, T.

    2014-03-01

    This paper presents an advanced study including the design, characterization and theoretical analysis of a capacitive vibration energy harvester. Although based on a resonant electromechanical device, it is intended for operation in a wide frequency band due to the combination of stop-end effects and a strong biasing electrical field. The electrostatic transducer has an interdigited comb geometry with in-plane motion, and is obtained through a simple batch process using two masks. A continuous conditioning circuit is used for the characterization of the transducer. A nonlinear model of the coupled system ‘transduce-conditioning circuit’ is presented and analyzed employing two different semi-analytical techniques together with precise numerical modelling. Experimental results are in good agreement with results obtained from numerical modelling. With the 1 g amplitude of harmonic external acceleration at atmospheric pressure, the system transducer-conditioning circuit has a half-power bandwidth of more than 30% and converts more than 2 µW of the power of input mechanical vibrations over the range of 140 and 160 Hz. The harvester has also been characterized under stochastic noise-like input vibrations.

  10. Effectiveness of Mechanical Debridement Combined With Adjunctive Therapies for Nonsurgical Treatment of Periimplantitis: A Systematic Review.

    PubMed

    de Almeida, Juliano Milanezi; Matheus, Henrique Rinaldi; Rodrigues Gusman, David Jonathan; Faleiros, Paula Lazilha; Januário de Araújo, Nathália; Noronha Novaes, Vivian Cristina

    2017-02-01

    This study aimed to perform a systematic review of the effectiveness of nonsurgical treatment associated with different adjuvant therapies on periimplantitis. Different individuals, following a research process, performed a network research of controlled and randomized controlled clinical trials on PubMed, Embase/MEDLINE, with 20 years' time constraint and the last search in January 2016. From 108 articles found by the first search, they analyzed 10 full texts, and in none did they find a standard control group. When compared, mechanical therapies combined with adjuvant therapy decreased prevalence of periimplant ratios; however, some groups showed unsatisfactory results, mainly related to the probing depth and bleeding index. When comparing debridement with other nonsurgical therapies (Er:YAG, Vector, air abrasive with amino acid glycine powder), increased periimplant levels were noticed in the test and control groups, although in different periods. Despite the improvement in the periimplant indices, there is no sufficient evidence to score the best results or even to choose the best association for nonsurgical treatment of periimplantitis; hence, more trials are necessary to answer this question.

  11. Angular approach combined to mechanical model for tool breakage detection by eddy current sensors

    NASA Astrophysics Data System (ADS)

    Ritou, M.; Garnier, S.; Furet, B.; Hascoet, J. Y.

    2014-02-01

    The paper presents a new complete approach for Tool Condition Monitoring (TCM) in milling. The aim is the early detection of small damages so that catastrophic tool failures are prevented. A versatile in-process monitoring system is introduced for reliability concerns. The tool condition is determined by estimates of the radial eccentricity of the teeth. An adequate criterion is proposed combining mechanical model of milling and angular approach.Then, a new solution is proposed for the estimate of cutting force using eddy current sensors implemented close to spindle nose. Signals are analysed in the angular domain, notably by synchronous averaging technique. Phase shifts induced by changes of machining direction are compensated. Results are compared with cutting forces measured with a dynamometer table.The proposed method is implemented in an industrial case of pocket machining operation. One of the cutting edges has been slightly damaged during the machining, as shown by a direct measurement of the tool. A control chart is established with the estimates of cutter eccentricity obtained during the machining from the eddy current sensors signals. Efficiency and reliability of the method is demonstrated by a successful detection of the damage.

  12. Combined toxicity and underlying mechanisms of a mixture of eight heavy metals.

    PubMed

    Zhou, Qi; Gu, Yuanliang; Yue, Xia; Mao, Guochuan; Wang, Yafei; Su, Hong; Xu, Jin; Shi, Hongbo; Zou, Baobo; Zhao, Jinshun; Wang, Renyuan

    2017-02-01

    With the rapid development of modernization and industrialization in China, a large quantity of heavy metals, including zinc, copper, lead, cadmium and mercury, have been entering the atmosphere, soil and water, the latter being the primary route of pollution. In the present study, in vitro experiments were performed to examine the joint toxicity and the underlying mechanisms of the eight most common heavy metals contaminating offshore waters on the eastern coast of Ningbo region. Using a cell cycle assay, cell apoptosis and reactive oxygen species (ROS) detection methods, the present study demonstrated that the heavy metal mixture arrested JB6 cells at the S phase, induced the generation of ROS and cell apoptosis. A luciferase assay indicated that the levels of activator protein‑1 and nuclear factor‑κB transcription factors were upregulated. Upregulation of the protein levels of C‑jun and p65 were detected in the JB6 cells by western blot analysis; these two genes have important roles in cell carcinogenesis. These results provide a useful reference for further investigations on the combined toxicity of the exposure to multiple heavy metals.

  13. Analysis of the mechanism of sludge ozonation by a combination of biological and chemical approaches.

    PubMed

    Yan, Sang-Tian; Chu, Li-Bing; Xing, Xin-Hui; Yu, An-Feng; Sun, Xu-Lin; Jurcik, Benjamin

    2009-01-01

    Using the practical sludge obtained from municipal sewage treatment plants, the mechanism of the sludge ozonation process was systematically investigated by a combination of biological and chemical approaches, including analysis of the changes in biological response by CFU and PCR-DGGE, bio-macromolecular activity and radical scavenging activity. The results indicated that after the sludge was exposed to ozone at less than 0.02 g O(3)/g TSS, the DGGE fingerprint remained constant and there was still some enzyme activity, indicating that the sludge solubilization was the main process. At greater than 0.02 g O(3)/g TSS, the bacteria began to be broken down and ozone was used to oxidize the bio-macromolecules such as proteins and DNA released from the sludge. Bacteria belonging to 'G-Bacteria' were able to conserve their DNA in the presence of less than 0.08 g O(3)/g TSS. At levels higher than 0.10 g O(3)/g TSS, the disintegration of the sludge matrix became slow and the microbes lost most of their activity, and ozone was used to transform the bio-macromolecules into small molecules. However, at levels higher than 0.14 g O(3)/g TSS, the ozone failed to oxidize the sludge efficiently, because several radical scavengers such as lactic acid and SO(4)(2-) were released from the microbial cells in the sludge.

  14. Cost-Effectiveness of Solitaire Stent Retriever Thrombectomy for Acute Ischemic Stroke: Results From the SWIFT-PRIME Trial (Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke).

    PubMed

    Shireman, Theresa I; Wang, Kaijun; Saver, Jeffrey L; Goyal, Mayank; Bonafé, Alain; Diener, Hans-Christoph; Levy, Elad I; Pereira, Vitor M; Albers, Gregory W; Cognard, Christophe; Hacke, Werner; Jansen, Olav; Jovin, Tudor G; Mattle, Heinrich P; Nogueira, Raul G; Siddiqui, Adnan H; Yavagal, Dileep R; Devlin, Thomas G; Lopes, Demetrius K; Reddy, Vivek K; du Mesnil de Rochemont, Richard; Jahan, Reza; Vilain, Katherine A; House, John; Lee, Jin-Moo; Cohen, David J

    2017-02-01

    Clinical trials have demonstrated improved 90-day outcomes for patients with acute ischemic stroke treated with stent retriever thrombectomy plus tissue-type plasminogen activator (SST+tPA) compared with tPA. Previous studies suggested that this strategy may be cost-effective, but models were derived from pooled data and older assumptions. In this prospective economic substudy conducted alongside the SWIFT-PRIME trial (Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke), in-trial costs were measured for patients using detailed medical resource utilization and hospital billing data. Utility weights were assessed at 30 and 90 days using the EuroQol-5 dimension questionnaire. Post-trial costs and life-expectancy were estimated for each surviving patient using a model based on trial data and inputs derived from a contemporary cohort of ischemic stroke survivors. Index hospitalization costs were $17 183 per patient higher for SST+tPA than for tPA ($45 761 versus $28 578; P<0.001), driven by initial procedure costs. Between discharge and 90 days, costs were $4904 per patient lower for SST+tPA than for tPA ($11 270 versus $16 174; P=0.014); total 90-day costs remained higher with SST+tPA ($57 031 versus $44 752; P<0.001). Higher utility values for SST+tPA led to higher in-trial quality-adjusted life years (0.131 versus 0.105; P=0.005). In lifetime projections, SST+tPA was associated with substantial gains in quality-adjusted life years (6.79 versus 5.05), cost savings of $23 203 per patient and was economically dominant when compared with tPA in 90% of bootstrap replicates. Among patients with acute ischemic stroke enrolled in the SWIFT-PRIME trial, SST increased initial treatment costs, but was projected to improve quality-adjusted life-expectancy and reduce healthcare costs over a lifetime horizon compared with tPA. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01657461. © 2016 American

  15. Generalized Hybrid-Orbital Method for Combining Density Functional Theory with Molecular Mechanicals

    PubMed Central

    Pu, Jingzhi; Gao, Jiali; Truhlar, Donald G.

    2015-01-01

    The generalized hybrid orbital (GHO) method has previously been formulated for combining molecular mechanics with various levels of quantum mechanics, in particular semiempirical neglect of diatomic differential overlap theory, ab initio Hartree–Fock theory, and self-consistent charge density functional tight-binding theory. To include electron-correlation effects accurately and efficiently in GHO calculations, we extend the GHO method to density functional theory in the generalized-gradient approximation and hybrid density functional theory (denoted by GHO-DFT and GHO-HDFT, respectively) using Gaussian-type orbitals as basis functions. In the proposed GHO-(H)DFT formalism, charge densities in auxiliary hybrid orbitals are included to calculate the total electron density. The orthonormality constraints involving the auxiliary Kohn–Sham orbitals are satisfied by carrying out the hybridization in terms of a set of Löwdin symmetrically orthogonalized atomic basis functions. Analytical gradients are formulated for GHO-(H)DFT by incorporating additional forces associated with GHO basis transformations. Scaling parameters are introduced for some of the one-electron integrals and are optimized to obtain the correct charges and geometry near the QM/MM boundary region. The GHO-(H)DFT method based on the generalized gradient approach (GGA) (BLYP and mPWPW91) and HDFT methods (B3 LYP, mPW1PW91, and MPW1K) is tested—for geometries and atomic charges—against a set of small molecules. The following quantities are tested: 1) the C–C stretch potential in ethane, 2) the torsional barrier for internal rotation around the central C–C bond in n-butane, 3) proton affinities for a set of alcohols, amines, thiols, and acids, 4) the conformational energies of alanine dipeptide, and 5) the barrier height of the hydrogenatom transfer between n-C4H10 and n-C4H9, where the reaction center is described at the MPW1K/6–31G(d) level of theory. PMID:16086343

  16. Interspecies diversity of erythrocyte mechanical stability at various combinations in magnitude and duration of shear stress, and osmolality.

    PubMed

    Nemeth, Norbert; Sogor, Viktoria; Kiss, Ferenc; Ulker, Pinar

    2016-10-05

    We hypothesized that the results of red blood cell mechanical stability test show interspecies differences. The comparative investigations were performed on blood samples obtained from rats, beagle dogs, pigs and healthy volunteers. Mechanical stress was applied in nine combinations: 30, 60 or 100 Pa shear stress for 100, 200 or 300 seconds. Generally, rat erythrocytes showed the highest capability of resistance. With the applied combinations of mechanical stress pig erythrocytes were the most sensitive. On human erythrocytes 60 Pa for 200 s was the minimum combination to result significant deformability deterioration. By increasing the magnitude and duration of the applied mechanical stress we experienced escalating deformability impairment in all species. 100 Pa shear stress for 300 seconds on human erythrocytes showed the largest deformability impairment. The mechanical stability test results were also dependent on osmolality. At hypoosmolar range (200 mOsmol/kg) the mechanical stress improved EI data mostly in rat and porcine blood. At higher osmolality (500 mOsmol/kg), the test did not show detectable difference, while in 250-300 mOsmol/kg range the differences were well observable. In summary, erythrocytes' capability of resistance against mechanical stress shows interspecies differences depending on the magnitude and duration of the applied stress, and on the osmolality.

  17. Transverse crack initiation under combined thermal and mechanical loading of Fibre Metal Laminates and Glass Fibre Reinforced Polymers

    NASA Astrophysics Data System (ADS)

    van de Camp, W.; Dhallé, M. M. J.; Warnet, L.; Wessel, W. A. J.; Vos, G. S.; Akkerman, R.; ter Brake, H. J. M.

    2017-02-01

    The paper describes a temperature-dependent extension of the classical laminate theory (CLT) that may be used to predict the mechanical behaviour of Fibre Metal Laminates (FML) at cryogenic conditions, including crack initiation. FML are considered as a possible alternative class of structural materials for the transport and storage of liquified gasses such as LNG. Combining different constituents in a laminate opens up the possibility to enhance its functionality, e.g. offering lower specific weight and increased damage tolerance. To explore this possibility, a test programme is underway at the University of Twente to study transverse crack initiation in different material combinations under combined thermal and mechanical loading. Specifically, the samples are tested in a three-point bending experiment at temperatures ranging from 77 to 293 K. These tests will serve as a validation of the model presented in this paper which, by incorporating temperature-dependent mechanical properties and differential thermal expansion, will allow to select optimal material combinations and laminate layouts. By combining the temperature-dependent mechanical properties and the differential thermal contraction explicitly, the model allows for a more accurate estimate of the resulting thermal stresses which can then be compared to the strength of the constituent materials.

  18. Effect of salmeterol/fluticasone combination on the dynamic changes of lung mechanics in mechanically ventilated COPD patients: a prospective pilot study

    PubMed Central

    Chen, Wei-Chih; Chen, Hung-Hsing; Chiang, Chi-Huei; Lee, Yu-Chin; Yang, Kuang-Yao

    2016-01-01

    Background The combined therapy of inhaled corticosteroids and long-acting beta-2 agonists for mechanically ventilated patients with COPD has never been explored. Therefore, the aim of this study was to investigate their dynamic effects on lung mechanics and gas exchange. Materials and methods Ten mechanically ventilated patients with resolution of the causes of acute exacerbations of COPD were included. Four puffs of salmeterol 25 μg/fluticasone 125 μg combination therapy were administered. Lung mechanics, including maximum resistance of the respiratory system (Rrs), end-inspiratory static compliance, peak inspiratory pressure (PIP), plateau pressure, and mean airway pressure along with gas exchange function were measured and analyzed. Results Salmeterol/fluticasone produced a significant improvement in Rrs and PIP after 30 minutes. With regard to changes in baseline values, salmeterol/fluticasone inhalation had a greater effect on PIP than Rrs. However, the therapeutic effects seemed to lose significance after 3 hours of inhaled corticosteroid/long-acting beta-2 agonist administration. Conclusion The combination of salmeterol/fluticasone-inhaled therapy in mechanically ventilated patients with COPD had a significant benefit in reducing Rrs and PIP. PMID:26869782

  19. Safety and efficacy of thrombectomy in acute ischaemic stroke (REVASCAT): 1-year follow-up of a randomised open-label trial.

    PubMed

    Dávalos, Antoni; Cobo, Erik; Molina, Carlos A; Chamorro, Angel; de Miquel, M Angeles; Román, Luis San; Serena, Joaquín; López-Cancio, Elena; Ribó, Marc; Millán, Mónica; Urra, Xabier; Cardona, Pere; Tomasello, Alejandro; Castaño, Carlos; Blasco, Jordi; Aja, Lucía; Rubiera, Marta; Gomis, Meritxell; Renú, Arturo; Lara, Blanca; Martí-Fàbregas, Joan; Jankowitz, Brian; Cerdà, Neus; Jovin, Tudor G

    2017-05-01

    The REVASCAT trial and other studies have shown that the neurovascular thrombectomy improves outcomes at 90 days post stroke. However, whether the observed benefit is sustained in the long term remains unknown. We report the results of the prespecified 12-month analysis of the REVASCAT trial. Patients with acute ischaemic stroke who could be treated within 8 h of symptom onset were randomly assigned to medical therapy (including intravenous alteplase when eligible) and neurovascular thrombectomy with Solitaire FR or medical therapy alone. The main secondary outcome measure at 1 year follow-up was disability, measured using the modified Rankin Scale (mRS), ranging from 0 (no symptoms) to 6 (death) with categories 5 (severe disability) and 6 (death) collapsed into one category (severe disability or death), analysed as the distribution of the mRS. Additional prespecified secondary outcome measures included health-related quality of life measured with the EuroQol five dimensions questionnaire (EQ-5D) utility index (ranging from -0·3 to 1, higher values indicate better quality of life), the rate of functional independence (mRS 0-2), and cognitive function measured with the Trail Making Test (reported elsewhere). Treatment allocation was open label but endpoints at 12 months were assessed by masked investigators. The trial was registered at ClinicalTrials.gov, number NCT01692379. From Nov 24, 2012, to Dec 12, 2014, 206 patients were randomly assigned to medical therapy plus endovascular treatment (n=103) or medical treatment alone (n=103), at four centres in Catalonia, Spain. At 12 months post randomisation, based on 205 of 206 outcomes available at 12 months, thrombectomy reduced disability over the range of the mRS (common adjusted odds ratio [aOR] 1·80, 95% CI 1·09-2·99), and improved functional independence (mRS=0-2; 45 [44%] of 103 patients vs 31 [30%] of 103 patients; aOR 1·86, 95% CI 1·01-3·44). Health-related quality of life was superior in the

  20. Catalytic Cycle of Multicopper Oxidases Studied by Combined Quantum- and Molecular-Mechanical Free-Energy Perturbation Methods.

    PubMed

    Li, Jilai; Farrokhnia, Maryam; Rulíšek, Lubomír; Ryde, Ulf

    2015-07-02

    We have used combined quantum mechanical and molecular mechanical free-energy perturbation methods in combination with explicit solvent simulations to study the reaction mechanism of the multicopper oxidases, in particular, the regeneration of the reduced state from the native intermediate. For 52 putative states of the trinuclear copper cluster, differing in the oxidation states of the copper ions and the protonation states of water- and O2-derived ligands, we have studied redox potentials, acidity constants, isomerization reactions, as well as water- and O2 binding reactions. Thereby, we can propose a full reaction mechanism of the multicopper oxidases with atomic detail. We also show that the two copper sites in the protein communicate so that redox potentials and acidity constants of one site are affected by up to 0.2 V or 3 pKa units by a change in the oxidation state of the other site.

  1. [Discovery of topiramate's new functions based on medicinal property combinations and study on its mechanism].

    PubMed

    Li, Guang-Ji; Gu, Hao; Guo, Wei-Jia; Zhang, Yan-Ling; Wang, Yun; Qiao, Yan-Jiang

    2014-07-01

    To study topiramate's new functions according to the medicinal property combinations, in order to apply the traditional Chinese medicinal theory in discovering new purposes of old drugs. According to New Traditional Chinese Medicinal Families--Chemical Traditional Chinese Medicines, the authors found out topiramate's property. Then based on the therapeutic principle of diabetes, hypertension, epilepsy and lung cancer, as well as the relations of efficacies and medicinal property combinations, they summarized the corresponding medicinal property combination modes, compared topiramate's medicinal property combination mode with corresponding medicinal property combination modes of these diseases, and predict topiramate's new functions. According to the comparison, the corresponding medicinal property combinations were consistent with topiramate's medicinal property combinations as evidenced by corresponding literatures, whereas other medicinal property combinations were not. Based on medicinal property combination modes, the authors screened topiramate's new functions according to e of TCM clinical experience, discovered topiramate's therapeutic effects on diabetes, hypertension and lung cancer in addition to epilepsy, and explore new drug function according to medicinal property combination modes, which could help greatly shorten the new drug R&D period.

  2. Effects and mechanisms of the combined pollution of lanthanum and acid rain on the root phenotype of soybean seedlings.

    PubMed

    Sun, Zhaoguo; Wang, Lihong; Zhou, Qing; Huang, Xiaohua

    2013-09-01

    Rare earth pollution and acid rain pollution are both important environmental issues worldwide. In regions which simultaneously occur, the combined pollution of rare earth and acid rain becomes a new environmental issue, and the relevant research is rarely reported. Accordingly, we investigated the combined effects and mechanisms of lanthanum ion (La(3+)) and acid rain on the root phenotype of soybean seedlings. The combined pollution of low-concentration La(3+) and acid rain exerted deleterious effects on the phenotype and growth of roots, which were aggravated by the combined pollution of high-concentration La(3+) and acid rain. The deleterious effects of the combined pollution were stronger than those of single La(3+) or acid rain pollution. These stronger deleterious effects on the root phenotype and growth of roots were due to the increased disturbance of absorption and utilization of mineral nutrients in roots. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Quantum Mechanics/Molecular Mechanics Method Combined with Hybrid All-Atom and Coarse-Grained Model: Theory and Application on Redox Potential Calculations.

    PubMed

    Shen, Lin; Yang, Weitao

    2016-04-12

    We developed a new multiresolution method that spans three levels of resolution with quantum mechanical, atomistic molecular mechanical, and coarse-grained models. The resolution-adapted all-atom and coarse-grained water model, in which an all-atom structural description of the entire system is maintained during the simulations, is combined with the ab initio quantum mechanics and molecular mechanics method. We apply this model to calculate the redox potentials of the aqueous ruthenium and iron complexes by using the fractional number of electrons approach and thermodynamic integration simulations. The redox potentials are recovered in excellent accordance with the experimental data. The speed-up of the hybrid all-atom and coarse-grained water model renders it computationally more attractive. The accuracy depends on the hybrid all-atom and coarse-grained water model used in the combined quantum mechanical and molecular mechanical method. We have used another multiresolution model, in which an atomic-level layer of water molecules around redox center is solvated in supramolecular coarse-grained waters for the redox potential calculations. Compared with the experimental data, this alternative multilayer model leads to less accurate results when used with the coarse-grained polarizable MARTINI water or big multipole water model for the coarse-grained layer.

  4. Quantitative assessment of device-clot interaction for stent retriever thrombectomy.

    PubMed

    van der Marel, Kajo; Chueh, Ju-Yu; Brooks, Olivia W; King, Robert M; Marosfoi, Miklos G; Langan, Erin T; Carniato, Sarena L; Gounis, Matthew J; Nogueira, Raul G; Puri, Ajit S

    2016-02-01

    Rapid revascularization in emergent large vessel occlusion with endovascular embolectomy has proven clinical benefit. We sought to measure device-clot interaction as a potential mechanism for efficient embolectomy. Two different radiopaque clot models were injected to create a middle cerebral artery occlusion in a patient-specific vascular phantom. A radiopaque stent retriever was deployed within the clot by unsheathing the device or a combination of unsheathing followed by pushing the device (n=8/group). High-resolution cone beam CT was performed immediately after device deployment and repeated after 5 min. An image processing pipeline was created to quantitatively evaluate the volume of clot that integrates with the stent, termed the clot integration factor (CIF). The CIF was significantly different for the two deployment variations when the device engaged the hard clot (p=0.041), but not the soft clot (p=0.764). In the hard clot, CIF increased significantly between post-deployment and final imaging datasets when using the pushing technique (p=0.019), but not when using the unsheathing technique (p=0.067). When we investigated the effect of time on CIF in the different clot models disregarding the technique, the CIF was significantly increased in the final dataset relative to the post-deployment dataset in both clot models (p=0.004-0.007). This study demonstrates in an in vitro system the benefit of pushing the Trevo stent during device delivery in hard clot to enhance integration. Regardless of delivery technique, clot-device integration increased in both clot models by waiting 5 min. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  5. Agreement Among Stroke Faculty and Fellows in Treating Ischemic Stroke Patients With Tissue-Type Plasminogen Activator and Thrombectomy.

    PubMed

    Ramadan, Ahmad-Riad; Denny, Mary Carter; Vahidy, Farhaan; Yamal, Jose-Miguel; Wu, Tzu-Ching; Sarraj, Amrou; Savitz, Sean; Grotta, James

    2017-01-01

    The aim of this study is to determine agreement among vascular neurology fellows and faculty in treating patients with acute ischemic stroke with intravenous tissue-type plasminogen activator and intra-arterial thrombectomy (IAT). Patients were evaluated simultaneously by at least 2 vascular neurology. Agreement was determined using kappa (κ) and intraclass correlation coefficients. In 60 patients, agreement was substantial for tissue-type plasminogen activator (κ=0.75 [95% confidence interval, 0.57-0.92]) and IAT (κ=0.63 [95% confidence interval, 0.30-0.96]), with no difference between fellow-fellow versus fellow-faculty. Intraclass correlation coefficient for National Institutes of Health Stroke Scale was 0.94 (95% confidence interval, 0.90-0.97) and κ for Alberta Stroke Program Early CT Score was 0.53 (95% confidence interval, 0.20-0.78). Rapidly improving or mild deficits caused disagreement for both tissue-type plasminogen activator and IAT, whereas interpretation of computed tomographic perfusion led to disagreement for IAT. We found substantial agreement between vascular neurology fellows and faculty in treating with tissue-type plasminogen activator or IAT. Areas for improvement include recognition of stroke mimics, consensus on treating less severe strokes, and use/interpretation of imaging. © 2016 American Heart Association, Inc.

  6. Combining colloidal probe atomic force and reflection interference contrast microscopy to study the compressive mechanics of hyaluronan brushes.

    PubMed

    Attili, Seetharamaiah; Richter, Ralf P

    2012-02-14

    We describe a method that combines colloidal probe atomic force microscopy (AFM) and reflection interference contrast microscopy (RICM) to characterize the mechanical properties of thin and solvated polymer films. When analyzing polymer films, a fundamental problem in colloidal probe AFM experiments is to determine the distance at closest approach between the probe and the substrate on which the film is deposited. By combining AFM and RICM in situ, forces and absolute distances can be measured simultaneously. Using the combined setup, we quantify the compressive mechanics of films of the polysaccharide hyaluronan that is end-grafted to a supported lipid bilayer. The experimental data, and comparison with polymer theory, show that hyaluronan films are well-described as elastic, very soft and highly solvated polymer brushes. The data on these well-defined films should be a useful reference for the investigation of the more complex hyaluronan-rich coats that surround many living cells.

  7. [Synergistic mechanism of steam explosion combined with laccase treatment for straw delignification].

    PubMed

    Li, Guanhua; Chen, Hongzhang

    2014-06-01

    Components separation is the key technology in biorefinery. Combination of steam explosion and laccase was used, and synergistic effect of the combined pretreatment was evaluated in terms of physical structure, chemical components and extraction of lignin. The results showed that steam explosion can destroy the rigid structure and increase the specific surface area of straw, which facilitated the laccase pretreatment. The laccase pretreatment can modify the lignin structure based on the Fourier transform infrared test, as a result the delignification of straw was enhanced. Nuclei Growth model with a time dependent rate constant can describe the delignification, and the kinetics parameters indicated that the combined pretreatment improved the reaction sites and made the delignification reaction more sensitive to temperature. The combined pretreatment enhanced delignification, and can be a promising technology as an alternative to the existing pretreatment.

  8. Inhibitory effect and mechanism of acarbose combined with gymnemic acid on maltose absorption in rat intestine

    PubMed Central

    Luo, Hong; Wang, Le Feng; Imoto, Toshiaki; Hiji, Yasutake

    2001-01-01

    AIM: To compare the combinative and individual effect of acarbose and gymnemic acid (GA) on maltose absorption and hydrolysis in small intestine to determine whether nutrient control in diabetic care can be improved by combination of them. METHODS: The absorption and hydrolysis of maltose were studied by cyclic perfusion of intestinal loops in situ and motility of the intestine was recorded with the intestinal ring in vitro using Wistar rats. RESULTS: The total inhibitory rate of maltose absorption was improved by the combination of GA (0.1 g/L-1.0 g/L) and acarbose (0.1 mmol/L-2.0 mmol/L) throughout their effective duration (P < 0.05, U test of Mann-Whitney), although the improvement only could be seen at a low dosage during the first hour. With the combination, inhibitory duration of acarbose on maltose absorption was prolonged to 3 h and the inhibitory effect onset of GA was fastened to 15 min. GA suppressed the intestinal mobility with a good correlation (r = 0.98) to the inhibitory effect of GA on maltose absorption and the inhibitory effect of 2 mmol/L (high dose) acarbose on maltose hydrolysis was dual modulated by 1 g/L GA in vivo indicating that the combined effects involved the functional alteration of intestinal barriers. CONCLUSION: There are augmented effects of acarbose and GA, which involve pre-cellular and paracellular barriers. Diabetic care can be improved by employing the combination. PMID:11819725

  9. SGLT2 inhibitor/DPP-4 inhibitor combination therapy - complementary mechanisms of action for management of type 2 diabetes mellitus.

    PubMed

    Dey, Jayant

    2017-04-03

    Type 2 diabetes mellitus is a progressive disease with multiple underlying pathophysiologic defects. Monotherapy alone cannot maintain glycemic control and leads to treatment failure. Ideally, a combination of glucose-lowering agents should have complementary mechanisms of action that address multiple pathophysiologic pathways, can be used at all stages of the disease, and be generally well tolerated with no increased risk of hypoglycemia, cardiovascular events, or weight gain. The combination should also provide conveniences for patients, such as oral dosing, single-pill formulations, and once-daily administration, potentially translating to improved adherence. Two classes of glucose-lowering agents that meet these criteria are the sodium glucose cotransporter-2 (SGLT2) inhibitors and dipeptidyl peptidase-4 (DPP-4) inhibitors. This article reviews the rationale for combination therapy with these agents, and evidence from clinical trials with empagliflozin and linagliptin or dapagliflozin and saxagliptin in the management of type 2 diabetes mellitus. Both combinations have been approved as single-pill formulations.

  10. Combined in vivo and ex vivo analysis of mesh mechanics in a porcine hernia model.

    PubMed

    Kahan, Lindsey G; Lake, Spencer P; McAllister, Jared M; Tan, Wen Hui; Yu, Jennifer; Thompson, Dominic; Brunt, L Michael; Blatnik, Jeffrey A

    2017-07-21

    Hernia meshes exhibit variability in mechanical properties, and their mechanical match to tissue has not been comprehensively studied. We used an innovative imaging model of in vivo strain tracking and ex vivo mechanical analysis to assess effects of mesh properties on repaired abdominal walls in a porcine model. We hypothesized that meshes with dissimilar mechanical properties compared to native tissue would alter abdominal wall mechanics more than better-matched meshes. Seven mini-pigs underwent ventral hernia creation and subsequent open repair with one of two heavyweight polypropylene meshes. Following mesh implantation with attached radio-opaque beads, fluoroscopic images were taken at insufflation pressures from 5 to 30 mmHg on postoperative days 0, 7, and 28. At 28 days, animals were euthanized and ex vivo mechanical testing performed on full-thickness samples across repaired abdominal walls. Testing was conducted on 13 mini-pig controls, and on meshes separately. Stiffness and anisotropy (the ratio of stiffness in the transverse versus craniocaudal directions) were assessed. 3D reconstructions of repaired abdominal walls showed stretch patterns. As pressure increased, both meshes expanded, with no differences between groups. Over time, meshes contracted 17.65% (Mesh A) and 0.12% (Mesh B; p = 0.06). Mesh mechanics showed that Mesh A deviated from anisotropic native tissue more than Mesh B. Compared to native tissue, Mesh A was stiffer both transversely and craniocaudally. Explanted repaired abdominal walls of both treatment groups were stiffer than native tissue. Repaired tissue became less anisotropic over time, as mesh properties prevailed over native abdominal wall properties. This technique assessed 3D stretch at the mesh level in vivo in a porcine model. While the abdominal wall expanded, mesh-ingrown areas contracted, potentially indicating stresses at mesh edges. Ex vivo mechanics demonstrate that repaired tissue adopts mesh properties, suggesting

  11. Single or in combination antimicrobial resistance mechanisms of Klebsiella pneumoniae contribute to varied susceptibility to different carbapenems.

    PubMed

    Tsai, Yu-Kuo; Liou, Ci-Hong; Fung, Chang-Phone; Lin, Jung-Chung; Siu, L Kristopher

    2013-01-01

    Resistance to carbapenems has been documented by the production of carbapenemase or the loss of porins combined with extended-spectrum β-lactamases or AmpC β-lactamases. However, no complete comparisons have been made regarding the contributions of each resistance mechanism towards carbapenem resistance. In this study, we genetically engineered mutants of Klebsiella pneumoniae with individual and combined resistance mechanisms, and then compared each resistance mechanism in response to ertapenem, imipenem, meropenem, doripenem and other antibiotics. Among the four studied carbapenems, ertapenem was the least active against the loss of porins, cephalosporinases and carbapenemases. In addition to the production of KPC-2 or NDM-1 alone, resistance to all four carbapenems could also be conferred by the loss of two major porins, OmpK35 and OmpK36, combined with CTX-M-15 or DHA-1 with its regulator AmpR. Because the loss of OmpK35/36 alone or the loss of a single porin combined with bla CTX-M-15 or bla DHA-1-ampR expression was only sufficient for ertapenem resistance, our results suggest that carbapenems other than ertapenem should still be effective against these strains and laboratory testing for non-susceptibility to other carbapenems should improve the accurate identification of these isolates.

  12. Shared and unique responses of plants to multiple individual stresses and stress combinations: physiological and molecular mechanisms

    PubMed Central

    Pandey, Prachi; Ramegowda, Venkategowda; Senthil-Kumar, Muthappa

    2015-01-01

    In field conditions, plants are often simultaneously exposed to multiple biotic and abiotic stresses resulting in substantial yield loss. Plants have evolved various physiological and molecular adaptations to protect themselves under stress combinations. Emerging evidences suggest that plant responses to a combination of stresses are unique from individual stress responses. In addition, plants exhibit shared responses which are common to individual stresses and stress combination. In this review, we provide an update on the current understanding of both unique and shared responses. Specific focus of this review is on heat–drought stress as a major abiotic stress combination and, drought–pathogen and heat–pathogen as examples of abiotic–biotic stress combinations. We also comprehend the current understanding of molecular mechanisms of cross talk in relation to shared and unique molecular responses for plant survival under stress combinations. Thus, the knowledge of shared responses of plants from individual stress studies and stress combinations can be utilized to develop varieties with broad spectrum stress tolerance. PMID:26442037

  13. Transcriptome Analysis of Sunflower Genotypes with Contrasting Oxidative Stress Tolerance Reveals Individual- and Combined- Biotic and Abiotic Stress Tolerance Mechanisms.

    PubMed

    Ramu, Vemanna S; Paramanantham, Anjugam; Ramegowda, Venkategowda; Mohan-Raju, Basavaiah; Udayakumar, Makarla; Senthil-Kumar, Muthappa

    2016-01-01

    In nature plants are often simultaneously challenged by different biotic and abiotic stresses. Although the mechanisms underlying plant responses against single stress have been studied considerably, plant tolerance mechanisms under combined stress is not understood. Also, the mechanism used to combat independently and sequentially occurring many number of biotic and abiotic stresses has also not systematically studied. From this context, in this study, we attempted to explore the shared response of sunflower plants to many independent stresses by using meta-analysis of publically available transcriptome data and transcript profiling by quantitative PCR. Further, we have also analyzed the possible role of the genes so identified in contributing to combined stress tolerance. Meta-analysis of transcriptomic data from many abiotic and biotic stresses indicated the common representation of oxidative stress responsive genes. Further, menadione-mediated oxidative stress in sunflower seedlings showed similar pattern of changes in the oxidative stress related genes. Based on this a large scale screening of 55 sunflower genotypes was performed under menadione stress and those contrasting in oxidative stress tolerance were identified. Further to confirm the role of genes identified in individual and combined stress tolerance the contrasting genotypes were individually and simultaneously challenged with few abiotic and biotic stresses. The tolerant hybrid showed reduced levels of stress damage both under combined stress and few independent stresses. Transcript profiling of the genes identified from meta-analysis in the tolerant hybrid also indicated that the selected genes were up-regulated under individual and combined stresses. Our results indicate that menadione-based screening can identify genotypes not only tolerant to multiple number of individual biotic and abiotic stresses, but also the combined stresses.

  14. Transcriptome Analysis of Sunflower Genotypes with Contrasting Oxidative Stress Tolerance Reveals Individual- and Combined- Biotic and Abiotic Stress Tolerance Mechanisms

    PubMed Central

    Ramu, Vemanna S.; Paramanantham, Anjugam; Ramegowda, Venkategowda; Mohan-Raju, Basavaiah; Udayakumar, Makarla

    2016-01-01

    In nature plants are often simultaneously challenged by different biotic and abiotic stresses. Although the mechanisms underlying plant responses against single stress have been studied considerably, plant tolerance mechanisms under combined stress is not understood. Also, the mechanism used to combat independently and sequentially occurring many number of biotic and abiotic stresses has also not systematically studied. From this context, in this study, we attempted to explore the shared response of sunflower plants to many independent stresses by using meta-analysis of publically available transcriptome data and transcript profiling by quantitative PCR. Further, we have also analyzed the possible role of the genes so identified in contributing to combined stress tolerance. Meta-analysis of transcriptomic data from many abiotic and biotic stresses indicated the common representation of oxidative stress responsive genes. Further, menadione-mediated oxidative stress in sunflower seedlings showed similar pattern of changes in the oxidative stress related genes. Based on this a large scale screening of 55 sunflower genotypes was performed under menadione stress and those contrasting in oxidative stress tolerance were identified. Further to confirm the role of genes identified in individual and combined stress tolerance the contrasting genotypes were individually and simultaneously challenged with few abiotic and biotic stresses. The tolerant hybrid showed reduced levels of stress damage both under combined stress and few independent stresses. Transcript profiling of the genes identified from meta-analysis in the tolerant hybrid also indicated that the selected genes were up-regulated under individual and combined stresses. Our results indicate that menadione-based screening can identify genotypes not only tolerant to multiple number of individual biotic and abiotic stresses, but also the combined stresses. PMID:27314499

  15. Combination Regimens of Radiation Therapy and Therapeutic Cancer Vaccines: Mechanisms and Opportunities

    PubMed Central

    Garnett-Benson, Charlie; Hodge, James W.; Gameiro, Sofia R.

    2014-01-01

    Radiation therapy is widely used with curative or palliative intent in the clinical management of multiple cancers. Although mainly aimed at direct tumor cell killing, mounting evidence suggests that radiation can alter the tumor to become an immunostimulatory milieu. Data suggest that the immunogenic effects of radiation can be exploited to promote synergistic antitumor effects in combination with immunotherapeutic agents. Here we review concepts associated with the immunogenic consequences of radiation therapy, and highlight how preclinical findings are translating into clinical benefit for patients receiving combination regimens of radiation therapy and therapeutic cancer vaccines. PMID:25481266

  16. Emergent stent-assisted angioplasty of extracranial internal carotid artery and intracranial stent-based thrombectomy in acute tandem occlusive disease: technical considerations.

    PubMed

    Cohen, José E; Gomori, Moshe; Rajz, Gustavo; Moscovici, Samuel; Leker, Ronen R; Rosenberg, Shai; Itshayek, Eyal

    2013-09-01

    Tandem occlusions of the internal carotid artery (ICA) and a major intracranial artery respond poorly to intravenous thrombolytic therapy, and are usually managed by endovascular means. This study describes experience with stent-assisted endovascular ICA revascularization and stent-based thrombectomy. In patients with tandem ICA-middle cerebral artery (MCA)/distal ICA occlusion, the carotid occlusion was recanalized by primary angioplasty and stent implantation, and the distal occlusion by stent-based thrombectomy. Two variant techniques are described. Seven consecutive patients, mean age 64.1 years (range 49-75) and mean admission National Institutes of Health Stroke Scale score of 23, were included. Occlusion sites were tandem proximal ICA and MCA trunk (six patients) and tandem proximal left ICA and ICA terminus (one patient). Complete recanalization with complete perfusion (Thrombolysis in Myocardial Infarction [TIMI] 3, Thrombolysis in Cerebral Infarction [TICI] 3) was achieved in six patients and partial recanalization with partial perfusion (TIMI 2, TICI 2A) in one. Mean time to therapy was 4.9 h (range 3-6.5); mean time to recanalization was 55 min (range 38-65 min). CT performed 1 day after recanalization showed cortical sparing (>90% of the cortex at risk) in seven patients. Five patients (72%) presented with good clinical outcome (modified Rankin Scale (mRS) score 0-2) at 1 month; one patient (patient No 7) reached an mRS score of 3 and one patient died. In selected cases of acute ICA occlusion and concomitant major vessel embolic stroke, angioplasty and stenting of the proximal occlusion and stent-based thrombectomy of the intracranial occlusion may be feasible, effective and safe, and provide early neurological improvement. Further experience and prospective studies are warranted.

  17. Comparison of paclitaxel and everolimus-eluting stents in ST-segment elevation myocardial infarction and influence of thrombectomy on outcomes. ESTROFA-IM study.

    PubMed

    de la Torre Hernández, José M; Alfonso, Fernando; Martin Yuste, Victoria; Sánchez Recalde, Angel; Jimenez Navarro, Manuel F; Pérez de Prado, Armando; Hernández, Felipe; Abdul-Jawad Altisent, Omar; Roura, Gerard; García Camarero, Tamara; Elizaga, Jaime; Calviño, Ramón; Moreu, Jose; Bosa, Francisco; Jimenez Mazuecos, Jesús; Ruiz-Arroyo, José R; Garcia Del Blanco, Bruno; Rumoso, José R

    2014-12-01

    We sought to compare the long-term clinical outcome of with ST-segment elevation myocardial infarction treated with paclitaxel-eluting stents or everolimus-eluting stents and the influence of thrombectomy on outcomes. The ESTROFA-IM is a multicenter retrospective registry collecting consecutive patients with infarction treated with these stents in 16 centers. Propensity-score matching was performed to select comparable stent groups and comparable groups with and without thrombectomy. After matching patients, 350 treated with everolimus-eluting stents and 350 with paclitaxel-eluting stents were included in the analysis. The clinical and angiographic characteristics were comparable in both groups. The 2-year incidence of death, infarction, and target lesion revascularization was 14.9% for paclitaxel-eluting stents and 11.5% for everolimus-eluting stents (P = .04) and the incidence of definite/probable thrombosis 4.3% and 1.4%, respectively (P = .01). The use of paclitaxel-eluting was an independent predictor for events (hazard ratio = 2.44, 95% confidence interval, 1.28-4.65; P = .006). The benefit of everolimus-eluting stents over paclitaxel-eluting stents regarding stent thrombosis was more evident in the nonthrombectomy subgroup (5.4% vs 1.4%; P = .01). A significant interaction was found in the subgroups with and without thombectomy in the comparison between paclitaxel-eluting stents and everolimus-eluting stents for the end-point of stent thrombosis (P = .039). The results of this multicenter registry suggest better clinical outcomes with the everolimus-eluting stents in ST-segment elevation myocardial infarction. The lower risk of thrombosis with these stents could be more relevant in the absence of thrombectomy. Copyright © 2014 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.

  18. Cardiopulmonary bypass (CPB) has no significant impact on survival in patients undergoing nephrectomy and level III-IV inferior vena cava thrombectomy; a multi-institutional analysis

    PubMed Central

    Dall'Era, Marc A.; Durbin-Johnson, Blythe; Carballido, Joaquín A.; Chandrasekar, Thenappan; Chromecki, Thomas; Ciancio, Gaetano; Daneshmand, Siamak; Gontero, Paolo; Gonzalez, Javier; Haferkamp, Axel; Hohenfellner, Markus; Huang, William C.; Espinós, Estefania Linares; Mandel, Philipp; Martinez-Salamanca, Juan I.; Master, Viraj A.; McKiernan, James M.; Montorsi, Francesco; Novara, Giacomo; Pahernik, Sascha; Palou, Juan; Pruthi, Raj S.; Rodriguez-Faba, Oscar; Russo, Paul; Scherr, Douglas S.; Shariat, Shahrokh F.; Spahn, Martin; Terrone, Carlo; Vergho, Daniel; Wallen, Eric M.; Xylinas, Evanguelos; Zigeuner, Richard; Libertino, John A.; Evans, Christopher P.

    2016-01-01

    Purpose The impact of cardiopulmonary bypass (CPB) usage in level III-IV tumor thrombectomy on surgical and oncologic outcomes is unknown. We sought to determine the impact of cardiopulmonary bypass (CPB) on overall and cancer specific survival, as well as surgical complication rates, and immediate outcomes in patients undergoing nephrectomy and level III-IV tumor thrombectomy with or without CPB. Patients and Methods We retrospectively analyzed 362 patients with RCC and with level III or IV tumor thrombus from 1992 to 2012 in 22 US and European centers. Cox proportional hazards models were used to compare overall and cancer-specific survival between patients with and without CPB. Perioperative mortality and complications rates were assessed using logistic regression analyses. Results The median overall survival was 24.6 months in non-CPB patients and 26.6 months in CPB patients. Overall survival and cancer-specific survival (CSS) did not differ significantly in both groups, neither in univariate analysis nor when adjusting for known risk factors. In multivariate analysis, no significant differences were seen in hospital LOS, Clavien 1-4 complication rate, intraoperative or 30 day mortality, and CSS between both groups. Limitations include the retrospective nature of the study. Conclusions In our multi-institutional analysis, the use of cardiopulmonary bypass did not significantly impact cancer specific survival or overall survival in patients undergoing nephrectomy and level III or IV tumor thrombectomy. Neither approach was independently associated with increased mortality in the multivariate analysis. Higher surgical complications were not independently associated with the use of CPB. PMID:25797392

  19. A combined methodology of multiplet and composite focal mechanism techniques for identifying seismologically active zones in Syria

    NASA Astrophysics Data System (ADS)

    Abdul-Wahed, Mohamad; Asfahani, Jamal; Al-Tahhan, Ibrahim

    2011-10-01

    This contribution is an attempt to enlarge the current knowledge about the focal mechanisms as well as the seismotectonic settings in Syria. The seismologically active zones have been identified by applying an appropriate methodology to the events recorded during the period 1995-2003 by the Syrian National Seismological Network (SNSN). The recorded events in Syria were classified as weak during the research period. It was extremely important to propose and apply an appropriate methodology to identify the focal mechanisms generating this seismic activity. The proposed methodology consists of applying a combination of two techniques: the multiplet and the composite focal mechanisms. The combination of many events in one composite focal mechanism was realized by a multiplet technique using the spectral coherence of the events as a measure of similarity. The application of the proposed methodology allows a data set of composite fault plane solutions to be obtained. Most of the composite fault plane solutions had strike-slip mechanisms which are in agreement with the configuration of seismogenic belts in Syria.

  20. Combining MR elastography and diffusion tensor imaging for the assessment of anisotropic mechanical properties: a phantom study.

    PubMed

    Qin, Eric C; Sinkus, Ralph; Geng, Guangqiang; Cheng, Shaokoon; Green, Michael; Rae, Caroline D; Bilston, Lynne E

    2013-01-01

    To investigate the anisotropic elasticity of soft tissues using MR elastography (MRE) combined with diffusion tensor imaging (DTI). The storage moduli parallel (μ(‖)) and perpendicular (μ(⊥)) to the local fiber orientation were calculated assuming a transversely isotropic model. The local fiber orientation was provided by DTI. The proposed technique was validated against rheometry using anisotropic viscoelastic phantoms with various fiber volume fractions (V(f) = 0%, 15%, and 35%) and bovine skeletal muscle samples. The anisotropic ratio (μ(‖)/μ(⊥)) as measured by MRE correlated well with rheometry for all samples (R(2) = 0.809). The combined MRE/DTI technique was also able to differentiate different levels of mechanical anisotropy with the mechanical anisotropy (μ(‖)/μ(⊥)) of the V(f) = 35% phantoms being significantly higher than the V(f) = 15% and the isotropic (V(f) = 0%) phantoms. The bovine muscle samples showed significantly higher mechanical anisotropy than all phantoms. This study has demonstrated the feasibility of the proposed imaging technique for characterizing mechanical anisotropy of anisotropic materials and biological tissues, and validated the mechanical anisotropy results. Copyright © 2012 Wiley-Liss, Inc.

  1. Control of a simulated arm using a novel combination of Cerebellar learning mechanisms

    NASA Technical Reports Server (NTRS)

    Assad, C.; Hartmann, M.; Paulin, M. G.

    2001-01-01

    We present a model of cerebellar cortex that combines two types of learning: feedforward predicitve association based on local Hebbian-type learning between granule cell ascending branch and parallel fiber inputs, and reinforcement learning with feedback error correction based on climbing fiber activity.

  2. Optical-mechanical system for on-combine segregation of wheat by grain protein concentration

    USDA-ARS?s Scientific Manuscript database

    Grain segregation by grain protein concentration (GPC) may help growers maximize revenues in markets that offer protein premiums. Our objective was to develop an on-combine system for automatically segregating wheat (Triticum aestivum L.) by GPC during harvest. A multispectral optical sensor scans...

  3. Control of a simulated arm using a novel combination of Cerebellar learning mechanisms

    NASA Technical Reports Server (NTRS)

    Assad, C.; Hartmann, M.; Paulin, M. G.

    2001-01-01

    We present a model of cerebellar cortex that combines two types of learning: feedforward predicitve association based on local Hebbian-type learning between granule cell ascending branch and parallel fiber inputs, and reinforcement learning with feedback error correction based on climbing fiber activity.

  4. Compositional and Mechanical Properties of Peanuts Roasted to Equivalent Colors using Different Time/Temperature Combinations

    USDA-ARS?s Scientific Manuscript database

    Peanuts in North America and Europe are primarily consumed after dry roasting. Standard industry practice is to roast peanuts to a specific surface color (Hunter L-value) for a given application; however, equivalent surface colors can be attained using different roast temperature/time combinations,...

  5. Effect of Different Time/Temperature Roast Combinations on Nutritional and Mechanical Properties of Peanuts

    USDA-ARS?s Scientific Manuscript database

    Peanuts in North America and Europe are primarily consumed after dry roasting. Standard industry practice is to roast peanuts to a specific surface color (Hunter L-value) for a given application; however, equivalent surface colors can be attained using different roast temperature/time combinations....

  6. Drink Refusal Training as Part of a Combined Behavioral Intervention: Effectiveness and Mechanisms of Change

    ERIC Educational Resources Information Center

    Witkiewitz, Katie; Donovan, Dennis M.; Hartzler, Bryan

    2012-01-01

    Objective: Many trials have demonstrated the effectiveness of cognitive behavioral interventions for alcohol dependence, yet few studies have examined why particular treatments are effective. This study was designed to evaluate whether drink refusal training was an effective component of a combined behavioral intervention (CBI) and whether change…

  7. Combined Enzymatic and Mechanical Cell Disruption and Lipid Extraction of Green Alga Neochloris oleoabundans

    PubMed Central

    Wang, Dongqin; Li, Yanqun; Hu, Xueqiong; Su, Weimin; Zhong, Min

    2015-01-01

    Microalgal biodiesel is one of the most promising renewable fuels. The wet technique for lipids extraction has advantages over the dry method, such as energy-saving and shorter procedure. The cell disruption is a key factor in wet oil extraction to facilitate the intracellular oil release. Ultrasonication, high-pressure homogenization, enzymatic hydrolysis and the combination of enzymatic hydrolysis with high-pressure homogenization and ultrasonication were employed in this study to disrupt the cells of the microalga Neochloris oleoabundans. The cell disruption degree was investigated. The cell morphology before and after disruption was assessed with scanning and transmission electron microscopy. The energy requirements and the operation cost for wet cell disruption were also estimated. The highest disruption degree, up to 95.41%, assessed by accounting method was achieved by the combination of enzymatic hydrolysis and high-pressure homogenization. A lipid recovery of 92.6% was also obtained by the combined process. The combined process was found to be more efficient and economical compared with the individual process. PMID:25853267

  8. Aspiration Thrombectomy for Treatment of ST-segment Elevation Myocardial Infarction: a Meta-analysis of 26 Randomized Trials in 11,943 Patients.

    PubMed

    Spitzer, Ernest; Heg, Dik; Stefanini, Giulio G; Stortecky, Stefan; Rutjes, Anne W S; Räber, Lorenz; Blöchlinger, Stefan; Pilgrim, Thomas; Jüni, Peter; Windecker, Stephan

    2015-09-01

    There is continued debate about the routine use of aspiration thrombectomy in patients with ST-segment elevation myocardial infarction. Our aim was to evaluate clinical and procedural outcomes of aspiration thrombectomy-assisted primary percutaneous coronary intervention compared with conventional primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction. We performed a meta-analysis of 26 randomized controlled trials with a total of 11 943 patients. Clinical outcomes were extracted up to maximum follow-up and random effect models were used to assess differences in outcomes. We observed no difference in the risk of all-cause death (pooled risk ratio = 0.88; 95% confidence interval, 0.74-1.04; P = .124), reinfarction (pooled risk ratio = 0.85; 95% confidence interval, 0.67-1.08; P = .176), target vessel revascularization (pooled risk ratio = 0.86; 95% confidence interval, 0.73-1.00; P = .052), or definite stent thrombosis (pooled risk ratio = 0.76; 95% confidence interval, 0.49-1.16; P = .202) between the 2 groups at a mean weighted follow-up time of 10.4 months. There were significant reductions in failure to reach Thrombolysis In Myocardial Infarction 3 flow (pooled risk ratio = 0.70; 95% confidence interval, 0.60-0.81; P < .001) or myocardial blush grade 3 (pooled risk ratio = 0.76; 95% confidence interval, 0.65-0.89; P = .001), incomplete ST-segment resolution (pooled risk ratio = 0.72; 95% confidence interval, 0.62-0.84; P < .001), and evidence of distal embolization (pooled risk ratio = 0.61; 95% confidence interval, 0.46-0.81; P = .001) with aspiration thrombectomy but estimates were heterogeneous between trials. Among unselected patients with ST-segment elevation myocardial infarction, aspiration thrombectomy-assisted primary percutaneous coronary intervention does not improve clinical outcomes, despite improved epicardial and myocardial parameters of reperfusion. Copyright © 2015 Sociedad Española de Cardiolog

  9. Molecular mechanisms of the cross-impact of pathological processes in combined diabetes and cancer. Research and clinical aspects.

    PubMed

    Aleksandrovski, Ya A

    2002-12-01

    The mechanisms of interaction and cross-impact of metabolic processes in a combined diabetes and cancer condition are discussed. A hypothesis is proposed whereby the processes responsible for destruction of the organism in the case of diabetes--long-term hyperglycemia and generation of methylglyoxal--may substantially impact tumor development. The hypothesis is based on the fact that both diabetes and carcinogenesis cause dysfunction of the vital cellular signal system regulated by the protein kinase C (PKC) family. Normalization of the PKC functional activity in the case of diabetes restrains development of diabetic complications and inhibits the processes of tumor growth and metastasizing in carcinogenesis. On this basis, an attempt is made to interpret both the detrimental and beneficial effects of diabetes on cancer. The resultant effect is determined by the type of tumor and the duration and level of hyperglycemia. The mechanisms of the impact of diabetes mellitus on cancer are analyzed to develop recommendations for combined cancer therapy options.

  10. Multi-Drug Resistance Transporters and a Mechanism-Based Strategy for Assessing Risks of Pesticide Combinations to Honey Bees.

    PubMed

    Guseman, Alex J; Miller, Kaliah; Kunkle, Grace; Dively, Galen P; Pettis, Jeffrey S; Evans, Jay D; vanEngelsdorp, Dennis; Hawthorne, David J

    2016-01-01

    Annual losses of honey bee colonies remain high and pesticide exposure is one possible cause. Dangerous combinations of pesticides, plant-produced compounds and antibiotics added to hives may cause or contribute to losses, but it is very difficult to test the many combinations of those compounds that bees encounter. We propose a mechanism-based strategy for simplifying the assessment of combinations of compounds, focusing here on compounds that interact with xenobiotic handling ABC transporters. We evaluate the use of ivermectin as a model substrate for these transporters. Compounds that increase sensitivity of bees to ivermectin may be inhibiting key transporters. We show that several compounds commonly encountered by honey bees (fumagillin, Pristine, quercetin) significantly increased honey bee mortality due to ivermectin and significantly reduced the LC50 of ivermectin suggesting that they may interfere with transporter function. These inhibitors also significantly increased honey bees sensitivity to the neonicotinoid insecticide acetamiprid. This mechanism-based strategy may dramatically reduce the number of tests needed to assess the possibility of adverse combinations among pesticides. We also demonstrate an in vivo transporter assay that provides physical evidence of transporter inhibition by tracking the dynamics of a fluorescent substrate of these transporters (Rhodamine B) in bee tissues. Significantly more Rhodamine B remains in the head and hemolymph of bees pretreated with higher concentrations of the transporter inhibitor verapamil. Mechanism-based strategies for simplifying the assessment of adverse chemical interactions such as described here could improve our ability to identify those combinations that pose significantly greater risk to bees and perhaps improve the risk assessment protocols for honey bees and similar sensitive species.

  11. Multi-Drug Resistance Transporters and a Mechanism-Based Strategy for Assessing Risks of Pesticide Combinations to Honey Bees

    PubMed Central

    Guseman, Alex J.; Miller, Kaliah; Kunkle, Grace; Dively, Galen P.; Pettis, Jeffrey S.; Evans, Jay D.; vanEngelsdorp, Dennis; Hawthorne, David J.

    2016-01-01

    Annual losses of honey bee colonies remain high and pesticide exposure is one possible cause. Dangerous combinations of pesticides, plant-produced compounds and antibiotics added to hives may cause or contribute to losses, but it is very difficult to test the many combinations of those compounds that bees encounter. We propose a mechanism-based strategy for simplifying the assessment of combinations of compounds, focusing here on compounds that interact with xenobiotic handling ABC transporters. We evaluate the use of ivermectin as a model substrate for these transporters. Compounds that increase sensitivity of bees to ivermectin may be inhibiting key transporters. We show that several compounds commonly encountered by honey bees (fumagillin, Pristine, quercetin) significantly increased honey bee mortality due to ivermectin and significantly reduced the LC50 of ivermectin suggesting that they may interfere with transporter function. These inhibitors also significantly increased honey bees sensitivity to the neonicotinoid insecticide acetamiprid. This mechanism-based strategy may dramatically reduce the number of tests needed to assess the possibility of adverse combinations among pesticides. We also demonstrate an in vivo transporter assay that provides physical evidence of transporter inhibition by tracking the dynamics of a fluorescent substrate of these transporters (Rhodamine B) in bee tissues. Significantly more Rhodamine B remains in the head and hemolymph of bees pretreated with higher concentrations of the transporter inhibitor verapamil. Mechanism-based strategies for simplifying the assessment of adverse chemical interactions such as described here could improve our ability to identify those combinations that pose significantly greater risk to bees and perhaps improve the risk assessment protocols for honey bees and similar sensitive species. PMID:26840460

  12. Antifungal mechanism of the combination of Cinnamomum verum and Pelargonium graveolens essential oils with fluconazole against pathogenic Candida strains.

    PubMed

    Essid, Rym; Hammami, Majdi; Gharbi, Dorra; Karkouch, Ines; Hamouda, Thouraya Ben; Elkahoui, Salem; Limam, Ferid; Tabbene, Olfa

    2017-08-01

    The present study aimed to investigate the anti-Candida activity of ten essential oils (EOs) and to evaluate their potential synergism with conventional drugs. The effect on secreted aspartic protease (SAP) activity and the mechanism of action were also explored. The antifungal properties of essential oils were investigated using standard micro-broth dilution assay. Only Cinnamomum verum, Thymus capitatus, Syzygium aromaticum, and Pelargonium graveolens exhibited a broad spectrum of activity against a variety of pathogenic Candida strains. Chemical composition of active essential oils was performed by gas chromatography-mass spectrometry (GC-MS). Synergistic effect was observed with the combinations C. verum/fluconazole and P. graveolens/fluconazole, with FIC value 0.37. Investigation of the mechanism of action revealed that C. verum EO reduced the quantity of ergosterol to 83%. A total inhibition was observed for the combination C. verum/fluconazole. However, P. graveolens EO may disturb the permeability barrier of the fungal cell wall. An increase of MIC values of P. graveolens EO and the combination with fluconazole was observed with osmoprotectants (sorbitol and PEG6000). Furthermore, the combination with fluconazole may affect ergosterol biosynthesis and disturb fatty acid homeostasis in C. albicans cells as the quantity of ergosterol and oleic acid was reduced to 52.33 and 72%, respectively. The combination of P. graveolens and C. verum EOs with fluconazole inhibited 78.31 and 64.72% SAP activity, respectively. To our knowledge, this is the first report underlying the mechanism of action and the inhibitory effect of SAP activity of essential oils in synergy with fluconazole. Naturally occurring phytochemicals C. verum and P. graveolens could be effective candidate to enhance the efficacy of fluconazole-based therapy of C. albicans infections.

  13. Simultaneous mechanical stiffness and electrical potential measurements of living vascular endothelial cells using combined atomic force and epifluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Callies, Chiara; Schön, Peter; Liashkovich, Ivan; Stock, Christian; Kusche-Vihrog, Kristina; Fels, Johannes; Sträter, Alexandra S.; Oberleithner, Hans

    2009-04-01

    The degree of mechanical stiffness of vascular endothelial cells determines the endogenous production of the vasodilating gas nitric oxide (NO). However, the underlying mechanisms are not yet understood. Experiments on vascular endothelial cells suggest that the electrical plasma membrane potential is involved in this regulatory process. To test this hypothesis we developed a technique that simultaneously measures the electrical membrane potential and stiffness of vascular endothelial cells (GM7373 cell line derived from bovine aortic endothelium) under continuous perfusion with physiological electrolyte solution. The cellular stiffness was determined by nano-indentation using an atomic force microscope (AFM) while the electrical membrane potential was measured with bis-oxonol, a voltage-reporting fluorescent dye. These two methods were combined using an AFM attached to an epifluorescence microscope. The electrical membrane potential and mechanical stiffness of the same cell were continuously recorded for a time span of 5 min. Fast fluctuations (in the range of seconds) of both the electrical membrane potential and mechanical stiffness could be observed that were not related to each other. In contrast, slow cell depolarizations (in the range of minutes) were paralleled by significant increases in mechanical stiffness. In conclusion, using the combined AFM-fluorescence technique we monitored for the first time simultaneously the electrical plasma membrane potential and mechanical stiffness in a living cell. Vascular endothelial cells exhibit oscillatory non-synchronized waves of electrical potential and mechanical stiffness. The sustained membrane depolarization, however, is paralleled by a concomitant increase of cell stiffness. The described method is applicable for any fluorophore, which opens new perspectives in biomedical research.

  14. Combined effects of chemical priming and mechanical stimulation on mesenchymal stem cell differentiation on nanofiber scaffolds

    PubMed Central

    Subramony, Siddarth D.; Su, Amanda; Yeager, Keith; Lu, Helen H.

    2014-01-01

    Functional tissue engineering of connective tissues such as the anterior cruciate ligament (ACL) remains a significant clinical challenge, largely due to the need for mechanically competent scaffold systems for grafting, as well as a reliable cell source for tissue formation. We have designed an aligned, polylactide-co-glycolide (PLGA) nanofiber-based scaffold with physiologically relevant mechanical properties for ligament regeneration. The objective of this study is to identify optimal tissue engineering strategies for fibroblastic induction of human mesenchymal stem cells (hMSC), testing the hypothesis that basic fibroblast growth factor (bFGF) priming coupled with tensile loading will enhance hMSC-mediated ligament regeneration. It was observed that compared to the unloaded, as well as growth factor-primed but unloaded controls, bFGF stimulation followed by physiologically relevant tensile loading enhanced hMSC proliferation, collagen production and subsequent differentiation into ligament fibroblast-like cells, upregulating the expression of types I and III collagen, as well as tenasin-C and tenomodulin. The results of this study suggest that bFGF priming increases cell proliferation, while mechanical stimulation of the hMSCs on the aligned nanofiber scaffold promotes fibroblastic induction of these cells. In addition to demonstrating the potential of nanofiber scaffolds for hMSC-mediated functional ligament tissue engineering, this study yields new insights into the interactive effects of chemical and mechanical stimuli on stem cell differentiation. PMID:24267271

  15. Combined effects of chemical priming and mechanical stimulation on mesenchymal stem cell differentiation on nanofiber scaffolds.

    PubMed

    Subramony, Siddarth D; Su, Amanda; Yeager, Keith; Lu, Helen H

    2014-06-27

    Functional tissue engineering of connective tissues such as the anterior cruciate ligament (ACL) remains a significant clinical challenge, largely due to the need for mechanically competent scaffold systems for grafting, as well as a reliable cell source for tissue formation. We have designed an aligned, polylactide-co-glycolide (PLGA) nanofiber-based scaffold with physiologically relevant mechanical properties for ligament regeneration. The objective of this study is to identify optimal tissue engineering strategies for fibroblastic induction of human mesenchymal stem cells (hMSC), testing the hypothesis that basic fibroblast growth factor (bFGF) priming coupled with tensile loading will enhance hMSC-mediated ligament regeneration. It was observed that compared to the unloaded, as well as growth factor-primed but unloaded controls, bFGF stimulation followed by physiologically relevant tensile loading enhanced hMSC proliferation, collagen production and subsequent differentiation into ligament fibroblast-like cells, upregulating the expression of types I and III collagen, as well as tenasin-C and tenomodulin. The results of this study suggest that bFGF priming increases cell proliferation, while mechanical stimulation of the hMSCs on the aligned nanofiber scaffold promotes fibroblastic induction of these cells. In addition to demonstrating the potential of nanofiber scaffolds for hMSC-mediated functional ligament tissue engineering, this study yields new insights into the interactive effects of chemical and mechanical stimuli on stem cell differentiation. © 2013 Published by Elsevier Ltd.

  16. Membrane degradation during combined chemical and mechanical accelerated stress testing of polymer electrolyte fuel cells

    NASA Astrophysics Data System (ADS)

    Lim, C.; Ghassemzadeh, L.; Van Hove, F.; Lauritzen, M.; Kolodziej, J.; Wang, G. G.; Holdcroft, S.; Kjeang, E.

    2014-07-01

    A cyclic open circuit voltage (COCV) accelerated stress test (AST) is designed to screen the simultaneous effect of chemical and mechanical membrane degradation in polymer electrolyte fuel cells. The AST consists of a steady state OCV phase to accelerate chemical degradation and periodic wet/dry cycles to provide mechanical degradation. The membrane degradation process induced by COCV AST operation is analyzed using a standard MEA with PFSA ionomer membrane. The OCV shows an initially mild decay rate followed by a higher decay rate in the later stages of the experiment. Membrane failure, defined by a threshold convective hydrogen leak rate, is obtained after 160 h of operation. Uniform membrane thinning is observed with pinhole formation being the primary cause of failure. Mechanical tensile tests reveal that the membrane becomes stiffer and more brittle during AST operation, which contributes to mechanical failure upon cyclic humidity induced stress. Solid state 19F NMR spectroscopy and fluoride emission measurements demonstrate fluorine loss from both side chain and main chain upon membrane exposure to high temperature and low humidity OCV condition.

  17. Enhancement of mechanical properties of 3D printed hydroxyapatite by combined low and high molecular weight polycaprolactone sequential infiltration.

    PubMed

    Suwanprateeb, Jintamai; Thammarakcharoen, Faungchat; Hobang, Nattapat

    2016-11-01

    A new infiltration technique using a combination of low and high molecular weight polycaprolactone (PCL) in sequence was developed as a mean to improve the mechanical properties of three dimensional printed hydroxyapatite (HA). It was observed that using either high (M n~80,000) or low (M n~10,000) molecular weight infiltration could only increase the flexural modulus compared to non-infiltrated HA, but did not affect strength, strain at break and energy at break. In contrast, a combination of low and high molecular infiltration in sequence increased the flexural modulus, strength and energy at break compared to those of non-infiltrated HA or infiltrated by high or low molecular weight PCL alone. This overall enhancement was found to be attributed to the densification of low molecular weight PCL and the reinforcement of high molecular PCL concurrently. The combined low and high molecular weight infiltration in sequence also maintained high osteoblast proliferation and differentiation of the composites at the similar level of the HA. Densification was a dominant mechanism for the change in modulus with porosity and density of the infiltrated HA/PCL composites. However, both densification and the reinforcing performance of the infiltration phase were crucial for strength and toughening enhancement of the composites possibly by the defect healing and stress shielding mechanisms. The sequence of using low molecular weight infiltration and followed by high molecular infiltration was seen to provide the greatest flexural properties and highest cells proliferation and differentiation capabilities.

  18. Top triangle moose: Combining Higgsless and topcolor mechanisms for mass generation

    SciTech Connect

    Chivukula, R. Sekhar; Christensen, Neil D.; Coleppa, Baradhwaj; Simmons, Elizabeth H.

    2009-08-01

    We present the details of a deconstructed model that incorporates both Higgsless and top-color mechanisms. The model alleviates the tension between obtaining the correct top quark mass and keeping {delta}{rho} small that exists in many Higgsless models. It does so by singling out the top quark mass generation as arising from a Yukawa coupling to an effective top Higgs which develops a small vacuum expectation value, while electroweak symmetry breaking results largely from a Higgsless mechanism. As a result, the heavy partners of the SM fermions can be light enough to be seen at the LHC. After presenting the model, we detail the phenomenology, showing that for a broad range of masses, these heavy fermions are discoverable at the LHC.

  19. Top triangle moose: Combining Higgsless and topcolor mechanisms for mass generation

    NASA Astrophysics Data System (ADS)

    Chivukula, R. Sekhar; Christensen, Neil D.; Coleppa, Baradhwaj; Simmons, Elizabeth H.

    2009-08-01

    We present the details of a deconstructed model that incorporates both Higgsless and top-color mechanisms. The model alleviates the tension between obtaining the correct top quark mass and keeping Δρ small that exists in many Higgsless models. It does so by singling out the top quark mass generation as arising from a Yukawa coupling to an effective top Higgs which develops a small vacuum expectation value, while electroweak symmetry breaking results largely from a Higgsless mechanism. As a result, the heavy partners of the SM fermions can be light enough to be seen at the LHC. After presenting the model, we detail the phenomenology, showing that for a broad range of masses, these heavy fermions are discoverable at the LHC.

  20. Cellular graphene aerogel combines ultralow weight and high mechanical strength: A highly efficient reactor for catalytic hydrogenation

    PubMed Central

    Zhang, Bingxing; Zhang, Jianling; Sang, Xinxin; Liu, Chengcheng; Luo, Tian; Peng, Li; Han, Buxing; Tan, Xiuniang; Ma, Xue; Wang, Dong; Zhao, Ning

    2016-01-01

    The construction of three-dimensional graphene aerogels (GAs) is of great importance owing to their outstanding properties for various applications. Up to now, the combination of ultralow weight and super mechanical strength for GA remains a great challenge. Here we demonstrate the fabrication of cellular GAs by a facile, easily controlled and versatile route, i.e. the chemical reduction of graphene oxide assemblies at oil-water interface under a mild condition (70 °C). The GA is ultralight (with density <3 mg cm−3) yet mechanically resilient because the walls of the cell closely pack in a highly ordered manner to maximize mechanical strength. The GA has been utilized as an appealing reactor for catalytic hydrogenation, which exhibited great advantages such as large oil absorption capability, exceptional catalytic activity, ease of product separation and high stability. PMID:27174450

  1. Cellular graphene aerogel combines ultralow weight and high mechanical strength: A highly efficient reactor for catalytic hydrogenation

    NASA Astrophysics Data System (ADS)

    Zhang, Bingxing; Zhang, Jianling; Sang, Xinxin; Liu, Chengcheng; Luo, Tian; Peng, Li; Han, Buxing; Tan, Xiuniang; Ma, Xue; Wang, Dong; Zhao, Ning

    2016-05-01

    The construction of three-dimensional graphene aerogels (GAs) is of great importance owing to their outstanding properties for various applications. Up to now, the combination of ultralow weight and super mechanical strength for GA remains a great challenge. Here we demonstrate the fabrication of cellular GAs by a facile, easily controlled and versatile route, i.e. the chemical reduction of graphene oxide assemblies at oil-water interface under a mild condition (70 °C). The GA is ultralight (with density <3 mg cm-3) yet mechanically resilient because the walls of the cell closely pack in a highly ordered manner to maximize mechanical strength. The GA has been utilized as an appealing reactor for catalytic hydrogenation, which exhibited great advantages such as large oil absorption capability, exceptional catalytic activity, ease of product separation and high stability.

  2. Controller design for flexible, distributed parameter mechanical arms via combined state space and frequency domain techniques

    NASA Technical Reports Server (NTRS)

    Book, W. J.; Majett, M.

    1982-01-01

    The potential benefits of the ability to control more flexible mechanical arms are discussed. A justification is made in terms of speed of movement. A new controller design procedure is then developed to provide this capability. It uses both a frequency domain representation and a state variable representation of the arm model. The frequency domain model is used to update the modal state variable model to insure decoupled states. The technique is applied to a simple example with encouraging results.

  3. The calculation of the thermal rate coefficient by a method combining classical and quantum mechanics

    NASA Astrophysics Data System (ADS)

    Wahnström, Göran; Carmeli, Benny; Metiu, Horia

    1988-02-01

    We propose and test a method for computing flux-flux correlation functions (and thermal rate coefficients) which divides the degrees of freedom in two groups, one treated classically and the other quantum mechanically. The method is tested by applying it to a simple model for which we can also obtain exact results. The approximate method gives good results if the mass associated with the classical degrees of freedom exceeds 16 a.u.

  4. Photochromic Mechanism of a Bridged Diarylethene: Combined Electronic Structure Calculations and Nonadiabatic Dynamics Simulations.

    PubMed

    Wang, Ya-Ting; Gao, Yuan-Jun; Wang, Qian; Cui, Ganglong

    2017-02-02

    Intramolecularly bridged diarylethenes exhibit improved photocyclization quantum yields because the anti-syn isomerization that originally suppresses photocyclization in classical diarylethenes is blocked. Experimentally, three possible channels have been proposed to interpret experimental observation, but many details of photochromic mechanism remain ambiguous. In this work we have employed a series of electronic structure methods (OM2/MRCI, DFT, TDDFT, RI-CC2, DFT/MRCI, and CASPT2) to comprehensively study excited state properties, photocyclization, and photoreversion dynamics of 1,2-dicyano[2,2]metacyclophan-1-ene. On the basis of optimized stationary points and minimum-energy conical intersections, we have refined experimentally proposed photochromic mechanism. Only an S1/S0 minimum-energy conical intersection is located; thus, we can exclude the third channel experimentally proposed. In addition, we find that both photocyclization and photoreversion processes use the same S1/S0 conical intersection to decay the S1 system to the S0 state, so we can unify the remaining two channels into one. These new insights are verified by our OM2/MRCI nonadiabatic dynamics simulations. The S1 excited-state lifetimes of photocyclization and photoreversion are estimated to be 349 and 453 fs, respectively, which are close to experimentally measured values: 240 ± 60 and 250 fs in acetonitrile solution. The present study not only interprets experimental observations and refines previously proposed mechanism but also provides new physical insights that are valuable for future experiments.

  5. Combined quantum mechanics (TDDFT) and classical electrodynamics (Mie theory) methods for calculating surface enhanced Raman and hyper-Raman spectra.

    PubMed

    Mullin, Jonathan; Valley, Nicholas; Blaber, Martin G; Schatz, George C

    2012-09-27

    Multiscale models that combine quantum mechanics and classical electrodynamics are presented, which allow for the evaluation of surface-enhanced Raman (SERS) and hyper-Raman scattering spectra (SEHRS) for both chemical (CHEM) and electrodynamic (EM) enhancement mechanisms. In these models, time-dependent density functional theory (TDDFT) for a system consisting of the adsorbed molecule and a metal cluster fragment of the metal particle is coupled to Mie theory for the metal particle, with the surface of the cluster being overlaid with the surface of the metal particle. In model A, the electromagnetic enhancement from plasmon-excitation of the metal particle is combined with the chemical enhancement associated with a static treatment of the molecule-metal structure to determine overall spectra. In model B, the frequency dependence of the Raman spectrum of the isolated molecule is combined with the enhancements determined in model A to refine the enhancement estimate. An equivalent theory at the level of model A is developed for hyper-Raman spectra calculations. Application to pyridine interacting with a 20 nm diameter silver sphere is presented, including comparisons with an earlier model (denoted G), which combines plasmon enhanced fields with gas-phase Raman (or hyper-Raman) spectra. The EM enhancement factor for spherical particles at 357 nm is found to be 10(4) and 10(6) for SERS and SEHRS, respectively. Including both chemical and electromagnetic mechanisms at the level of model A leads to enhancements on the order of 10(4) and 10(9) for SERS and SEHRS.

  6. Formation of Hot Planets by a Combination of Planet Scattering, Tidal Circularization, and the Kozai Mechanism

    NASA Astrophysics Data System (ADS)

    Nagasawa, M.; Ida, S.; Bessho, T.

    2008-05-01

    We have investigated the formation of close-in extrasolar giant planets through a coupling effect of mutual scattering, the Kozai mechanism, and tidal circularization, by orbital integrations. Close-in gas giants would have been originally formed at several AU beyond the ice lines in protoplanetary disks and migrated close to their host stars. Although type II migration due to planet-disk interactions may be a major channel for the migration, we show that this scattering process would also give a nonnegligible contribution. We carried out orbital integrations of three planets with Jupiter mass, directly including the effect of tidal circularization. We have found that in about 30% of the runs close-in planets are formed, which is much higher than suggested by previous studies. Three-planet orbit crossing usually results in the ejection of one or two planets. Tidal circularization often occurs during three-planet orbit crossing, but previous studies have monitored only the final stage after the ejection, significantly underestimating the formation probability. We have found that the Kozai mechanism in outer planets is responsible for the formation of close-in planets. During three-planet orbital crossing, Kozai excitation is repeated and the eccentricity is often increased secularly to values close enough to unity for tidal circularization to transform the inner planet to a close-in planet. Since a moderate eccentricity can retain for the close-in planet, this mechanism may account for the observed close-in planets with moderate eccentricities and without nearby secondary planets. Since these planets also remain a broad range of orbital inclinations (even retrograde ones), the contribution of this process would be clarified by more observations of Rossiter-McLaughlin effects for transiting planets.

  7. Mechanisms of tramadol-related neurotoxicity in the rat: Does diazepam/tramadol combination play a worsening role in overdose?

    PubMed

    Lagard, Camille; Chevillard, Lucie; Malissin, Isabelle; Risède, Patricia; Callebert, Jacques; Labat, Laurence; Launay, Jean-Marie; Laplanche, Jean-Louis; Mégarbane, Bruno

    2016-11-01

    Poisoning with opioid analgesics including tramadol represents a challenge. Tramadol may induce respiratory depression, seizures and serotonin syndrome, possibly worsened when in combination to benzodiazepines. Our objectives were to investigate tramadol-related neurotoxicity, consequences of diazepam/tramadol combination, and mechanisms of drug-drug interactions in rats. Median lethal-doses were determined using Dixon-Bruce's up-and-down method. Sedation, seizures, electroencephalography and plethysmography parameters were studied. Concentrations of tramadol and its metabolites were measured using liquid-chromatography-high-resolution-mass-spectrometry. Plasma, platelet and brain monoamines were measured using liquid-chromatography coupled to fluorimetry. Median lethal-doses of tramadol and diazepam/tramadol combination did not significantly differ, although time-to-death was longer with combination (P=0.04). Tramadol induced dose-dependent sedation (P<0.05), early-onset seizures (P<0.001) and increase in inspiratory (P<0.01) and expiratory times (P<0.05). The diazepam/tramadol combination abolished seizures but significantly enhanced sedation (P<0.01) and respiratory depression (P<0.05) by reducing tidal volume (P<0.05) in addition to tramadol-related increase in respiratory times, suggesting a pharmacodynamic mechanism of interaction. Plasma M1 and M5 metabolites were mildly increased, contributing additionally to tramadol-related respiratory depression. Tramadol-induced early-onset increase in brain concentrations of serotonin and norepinephrine was not significantly altered by the diazepam/tramadol combination. Interestingly neither pretreatment with cyproheptadine (a serotonin-receptor antagonist) nor a benserazide/5-hydroxytryptophane combination (enhancing brain serotonin) reduced tramadol-induced seizures. Our study shows that diazepam/tramadol combination does not worsen tramadol-induced fatality risk but alters its toxicity pattern with enhanced

  8. The combined influence of chemical, metallurgical and mechanical factors on environment assisted cracking

    NASA Technical Reports Server (NTRS)

    Williams, D. P., III; Pao, P. S.; Wei, R. P.

    1979-01-01

    The principal aim of the paper is to re-emphasize and focus on both the multidisciplinary nature of the environment assisted cracking or embrittlement phenomenon. The multiplicity of factors involved in the embrittlement process is indicated, the mutual dependence of these factors and the influences of mechanical and environmental conditions are considered, and the interactions of various factors in determining the overall embrittlement response are discussed. The need for an interdisciplinary approach for resolving the major differences and for understanding embrittlement is outlined.

  9. A combined experimental-numerical approach for determining mechanical properties of aluminum subjects to nanoindentation

    PubMed Central

    Liu, Mao; Lu, Cheng; Tieu, Kiet Anh; Peng, Ching-Tun; Kong, Charlie

    2015-01-01

    A crystal plasticity finite element method (CPFEM) model has been developed to investigate the mechanical properties and micro-texture evolution of single-crystal aluminum induced by a sharp Berkovich indenter. The load-displacement curves, pile-up patterns and lattice rotation angles from simulation are consistent with the experimental results. The pile-up phenomenon and lattice rotation have been discussed based on the theory of crystal plasticity. In addition, a polycrystal tensile CPFEM model has been established to explore the relationship between indentation hardness and yield stress. The elastic constraint factor C is slightly larger than conventional value 3 due to the strain hardening. PMID:26464128

  10. Rapid diffusion of magic-size islands by combined glide and vacancy mechanisms

    SciTech Connect

    Perez, D; Voter, A F; Uche, O U; Hamilton, J C

    2009-01-01

    Using molecular dynamics, nudged elastic band, and embedded atom methods, we show that certain 2D Ag islands undergo extremely rapid one-dimensional diffusion on Cu(001) surfaces. Indeed, below 300K, hopping rates for 'magic-size' islands are orders of magnitude faster than hopping rates for single Ag adatoms. This rapid diffusion requires both the c(10 x 2) hexagonally-packed superstructure typical of Ag on Cu(001) and appropriate 'magic-sizes' for the islands. The novel highly-cooperative diffusion mechanism presented here couples vacancy diffusion with simultaneous core glide.

  11. Deprotonation mechanism of new antihypertensive piperidinylmethylphenols: a combined experimental and theoretical study.

    PubMed

    Islas-Martínez, José Manuel; Rodríguez-Barrientos, Damaris; Galano, Annia; Angeles, Enrique; Torres, Luis A; Olvera, Fabiola; Ramírez-Silva, María Teresa; Rojas-Hernández, Alberto

    2009-08-27

    Four new antihypertensive piperidinylmethylphenol compounds were synthesized for their potential antihypertensive and antiarhythmic properties. The pKa values were determined experimentally, with the aid of the program SQUAD, by capillary zone electrophoresis (CZE) at T=298.15 K and 0.015 M ionic strength (I=0.05 M) and by UV spectrophotometry at pseudophysiological conditions (T=310.15 K and I=0.15 M), obtaining good agreement between the values determined with both techniques. A theoretical study was followed in order to propose a deprotonation mechanism for each compound.

  12. A combined experimental-numerical approach for determining mechanical properties of aluminum subjects to nanoindentation.

    PubMed

    Liu, Mao; Lu, Cheng; Tieu, Kiet Anh; Peng, Ching-Tun; Kong, Charlie

    2015-10-14

    A crystal plasticity finite element method (CPFEM) model has been developed to investigate the mechanical properties and micro-texture evolution of single-crystal aluminum induced by a sharp Berkovich indenter. The load-displacement curves, pile-up patterns and lattice rotation angles from simulation are consistent with the experimental results. The pile-up phenomenon and lattice rotation have been discussed based on the theory of crystal plasticity. In addition, a polycrystal tensile CPFEM model has been established to explore the relationship between indentation hardness and yield stress. The elastic constraint factor C is slightly larger than conventional value 3 due to the strain hardening.

  13. Histopathology combined with transcriptome analyses revea