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DSA
Kinds of DSA Selected AbstractsTumor imaging in small animals with a combined micro-CT/micro-DSA system using iodinated conventional and blood pool contrast agentsCONTRAST MEDIA & MOLECULAR IMAGING, Issue 4 2006Cristian T. Badea Abstract X-ray based micro-computed tomography (CT) and micro-digital subtraction angiography (DSA) are important non-invasive imaging modalities for following tumorogenesis in small animals. To exploit these imaging capabilities further, the two modalities were combined into a single system to provide both morphological and functional data from the same tumor in a single imaging session. The system is described and examples are given of imaging implanted fibrosarcoma tumors in rats using two types of contrast media: (a) a new generation of blood pool contrast agent containing iodine with a concentration of 130,mg/mL (FenestraÔ VC, Alerion Biomedical, San Diego, CA, USA) for micro-CT and (b) a conventional iodinated contrast agent (Isovue®-370,mg/mL iodine, trademark of Bracco Diagnostics, Princeton, NJ, USA) for micro-DSA. With the blood pool contrast agent, the 3D vascular architecture is revealed in exquisite detail at 100,µm resolution. Micro-DSA images, in perfect registration with the 3D micro-CT datasets, provide complementary functional information such as mean transit times and relative blood flow through the tumor. This imaging approach could be used to understand tumor angiogenesis better and be the basis for evaluating anti-angiogenic therapies. Copyright © 2006 John Wiley & Sons Ltd. [source] Ruptured symptomatic internal carotid artery dorsal wall aneurysm with rapid configurational change.EUROPEAN JOURNAL OF NEUROLOGY, Issue 10 2010Clinical experience, management outcome: an original article Background:, Aneurysms located at non-branching sites, protruding from the dorsal wall of the supraclinoid internal carotid artery (ICA) with rapid configurational changes, were retrospectively reviewed in effort to identify and characterize these high-risk aneurysms. Methods:, A total of 447 patients with 491 intracranial aneurysms were treated from March 2005 to August 2008, and of these, eight patients had ICA dorsal wall aneurysms. Four of them suffered subarachnoid hemorrhage (SAH), and all had aneurysms undergoing rapid configuration changes during the treatment course. Digital subtraction cerebral angiography (DSA) performed soon after the SAH events. Data analyzed were patient age, sex, Hunt and Kosnik grade, time interval from first DSA to second DSA, aneurysm treatment, and modified Rankin scale score after treatment for 3 months. Success or failure of therapeutic management was examined among the patients. Results:, Digital subtraction cerebral angiography showed only lesions with small bulges in the dorsal walls of the ICAs. However, the patients underwent DSA again for re-bleeding or for post-treatment follow-up, confirming the SAH source. ICA dorsal wall aneurysms with rapid growth and configurational changes were found on subsequent DSA studies. Conclusions:, Among the four patients, ICA dorsal wall aneurysms underwent rapid growth with configurational change from a blister type to a saccular type despite different management. ICA trapping including the lesion segment can be considered as the first treatment option if the balloon occlusion test (BOT) is successful. If a BOT is not tolerated by the patient, extracranial,intracranial bypass revascularization surgery with endovascular ICA occlusion is another treatment option. [source] On-line dynamic security assessment to mitigate the risk of blackout in the Italian power systemEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 8 2008Diego Cirio Abstract This paper provides a comprehensive survey of the major initiatives and research projects recently carried out by the Italian system operator, Cesi Ricerca, and Universities on power system monitoring, defense, and security assessment. The technological and methodological features of an advanced wide area measurement system (WAMS) are described and the main aspects of an adaptive system for event-based automatic load shedding are presented. Then preventive and corrective security assessment, with particular emphasis to dynamic security assessment,DSA, is introduced. Results from an EU project, where the Italian power system served as a test site for on-line experimentation, are reported. Considering the need for very fast assessment by stability indices, a complementary approach to the above "conventional" DSA, currently under way, is described in further detail. The methodology relies on a correlation model relating significant power system measurements with local loadability margins. Results of some tests on the Italian power system are presented and discussed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Groundwater parameter estimation via the unsteady adjoint variable formulation of discrete sensitivity analysisINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 6 2002C. O. E. Burg Abstract Discrete sensitivity analysis (DSA) is a method that efficiently estimates the derivatives of a numerically approximated objective function with respect to a set of parameters at a fraction of the cost of using finite differences. Coupled with an optimization algorithm, this method can be used to locate the optimal set of parameters for the objective function. The time dependent adjoint variable formulation of discrete sensitivity analysis is derived and applied to a time-dependent, two-dimensional groundwater code. The derivatives agreed with finite difference derivatives to between 6 and 8 significant digits, at approximately , the computational cost. Using the BFGS optimization algorithm to update the parameters, the parameter estimation technique successfully identified the target values, for problems with small number of parameters. Copyright © 2002 John Wiley & Sons, Ltd. [source] Die shape design optimization of sheet metal stamping process using meshfree methodINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 12 2001Nam Ho Kim Abstract A die shape design sensitivity analysis (DSA) and optimization for a sheet metal stamping process is proposed based on a Lagrangian formulation. A hyperelasticity-based elastoplastic material model is used for the constitutive relation that includes a large deformation effect. The contact condition between a workpiece and a rigid die is imposed through the penalty method with a modified Coulomb friction model. The domain of the workpiece is discretized by a meshfree method. A continuum-based DSA with respect to the rigid die shape parameter is formulated using a design velocity concept. The die shape perturbation has an effect on structural performance through the contact variational form. The effect of the deformation-dependent pressure load to the design sensitivity is discussed. It is shown that the design sensitivity equation uses the same tangent stiffness matrix as the response analysis. The linear design sensitivity equation is solved at each converged load step without the need of iteration, which is quite efficient in computation. The accuracy of sensitivity information is compared to that of the finite difference method with an excellent agreement. A die shape design optimization problem is solved to obtain the desired shape of the workpiece to minimize spring-back effect and to show the feasibility of the proposed method. Copyright © 2001 John Wiley & Sons, Ltd. [source] A retrospective review of the outcome of plasma exchange and aggressive medical therapy in antibody mediated rejection of renal allografts: A single center experienceJOURNAL OF CLINICAL APHERESIS, Issue 6 2008Wisam Al-Badr Abstract Antibody-mediated rejection (AMR) has been recognized as a major cause of renal allograft loss. Protocols using plasma exchange (PE) to reverse rejection have mixed results. Methods: A retrospective chart review was performed to determine the clinical response to PE inpatients with AMR of renal allograft. A good response to treatment was defined as a decline in serum creatinine (SCr) to within 25% above the prerejection value or discontinuation of dialysis with a SCr <2 mg/dl within 3 months of discharge from the hospital and disappearance of donor-specific alloantibodies (DSA). Results: Twenty-two patients, treated with PE for biopsy proven AMR with or without acute-cellular rejection (ACR), were included in the study. Sixty-four percent of patients had concurrent AMR and ACR. Fifty-two percent of all patients had a good response to antirejection therapy, whereas 63% of patients with only AMR and 46% of patients with both AMR and ACR had a good response. Good response to PE did not correlate with the number of plasma volumes exchanged (P = 0.09), but correlated with a shorter period from transplantation to the rejection episode (P = 0.002). Conclusion: Only a shorter interval between transplantation and the acute rejection episode correlated with a good response to PE. J. Clin. Apheresis, 2008. © 2008 Wiley-Liss, Inc. [source] Extracranial and intracranial vertebral artery dissection: Long-term clinical and duplex sonographic follow-upJOURNAL OF CLINICAL ULTRASOUND, Issue 8 2008Tiemo Wessels MD Abstract Purpose. To determine the value of color Doppler sonography (CDUS) in the diagnosis and follow-up of patients with extracranial and intracranial vertebral artery (VA) dissection. Method. Thirty-three patients aged 42 ± 12 years with 40 VADS confirmed via digital subtraction angiography (DSA) (n = 37) and magnetic resonance angiography (MRA) (n = 3) were included in the study. All patients were investigated with extracranial CDUS and transcranial CDUS (TCCDUS) over a mean ± SD follow-up period of 42 ± 24 months and occurrence of new ischemic symptoms was assessed. Sonographic results were compared with initial and follow-up angiographic results. Results. At presentation, 24/33 (73%) patients had suffered an ischemic stroke, 5/33 (15%) had a transient ischemic attack (TIA), and 4/33 (12%) were asymptomatic. Two patients had a recurrent vertebrobasilar TIA; there was no recurrent stroke. The initial DSA findings consisted of 14 stenoses, 20 tapered occlusions, and 6 pseudoaneurysms. During follow-up, 63% of the vessels recanalized. Sonographic findings were consistent with angiographic findings in 80% at the initial examination and in 86% during follow-up. The main reason for discordant results was the failure of CDUS to detect pseudoaneurysms. No recurrence occurred in the vertebral arteries (VA), but 1 patient had an asymptomatic carotid artery dissection during follow-up. Conclusion. Recurrent TIA or stroke after VAD appears to be extremely rare, independent of recanalization or persistent occlusion of the affected artery. CDUS and TCCDUS provide reliable follow-up of VAD in all patients presenting with stenosis or occlusion, but do not allow for detection of pseudoaneurysms of the VA. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2008 [source] Contrast-enhanced power Doppler sonography of ductal pancreatic adenocarcinomas: Correlation with digital subtraction angiography findingsJOURNAL OF CLINICAL ULTRASOUND, Issue 4 2004Chien-Hua Chen MD Abstract Purpose The purpose of this prospective study was to utilize contrast-enhanced power Doppler sonography to evaluate the enhancement characteristics of ductal pancreatic adenocarcinomas and correlate them with the tumor vascularity observed on digital subtraction angiography (DSA). Methods Twenty consecutive patients with ductal pancreatic adenocarcinoma underwent power Doppler sonography and DSA. Tumor vascularity was assessed using unenhanced and contrast-enhanced power Doppler sonography. The contrast agent Levovist was administered intravenously by bolus injection of a dose of 2.5 g at a concentration of 350 mg/mL; saline was administered immediately thereafter. The patients were asked to hold their breath for 30 seconds (for the period 15,45 seconds after saline injection) while the early phase of enhancement was studied; the delayed phase of enhancement was observed between 60 and 120 seconds after saline administration, while patients breathed gently. Results None of the 20 pancreatic carcinomas showed any color signals on power Doppler sonography before administration of the contrast medium. Seventeen (85%) of the 20 pancreatic carcinomas also showed no enhancement in the early and delayed phases of contrast-enhanced power Doppler sonography. However, in the early phase of contrast-enhanced power Doppler sonography; 1 lesion showed pronounced enhancement and 2 showed mild enhancement. On DSA, the 17 carcinomas showing no enhancement on power Doppler sonography were found to be hypovascular, whereas the remaining 3 carcinomas with contrast enhancement on power Doppler sonography were found to be hypervascular. Conclusions The enhancement characteristics of the ductal pancreatic adenocarcinomas correlated well with the tumor vascularity observed on DSA. However, further study is needed to determine the accuracy of contrast-enhanced sonography in the diagnosis of pancreatic masses. © 2004 Wiley Periodicals, Inc. J Clin Ultrasound 32:179,185, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.20018 [source] Desensitizing Agent Efficacy during Whitening in an At-Risk PopulationJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 1 2004RALPH H. LEONARD Jr. DDS. ABSTRACT Background: Nightguard vital bleaching (NGVB) has gained acceptance among dentists and patients as a simple and effective procedure to lighten discolored teeth. Although the efficacy and predictability of NGVB have been well established, it has been documented that patients undergoing the procedure may experience side effects such as tooth sensitivity (TS) and gingival irritation (GI). A previous NGVB study suggested that selected participants might benefit from a regimen of a desensitizing agent (DSA)to decrease or prevent TS during whitening. Purpose: The purpose of this study was to determine whether the daily use of an active DSA (UltraEZTM, Ultradent Products Inc., South Jordan, UT, USA) during NGVB would decrease TS in a population at risk for TS when compared with a placebo. Materials and Methods: Forty subjects participated in this single-blind randomized clinical trial. All participants had indicated that they had preexisting TS or other risk factors for TS during NGVB. To evaluate TS caused by the tray alone, participants wore custom-fitted maxillary whitening trays containing no DSA or whitening solution during week 1. Next, participants were randomly assigned to apply either the active DSA or placebo daily for 14 days in the trays for 30 minutes prior to whitening. The placebo was the same formulation as UltraEZ but without the desensitizing agents (3% potassium nitrate and 0.11% by weight fluoride ion). The bleaching solution was a 10% carbamide peroxide whitening solution (OpalescenceTM, Ultradent Inc.). Post treatment, participants were followed up for 1 week, during which time they used neither trays nor solutions. Throughout the study, participants completed a daily diary to record their perceptions of TS and the time spent wearing the tray with the whitening solution. Results: Forty-one percent of the active group had at least 1 day of TS during treatment compared with 78% of the placebo group. The difference was statistically significant (p= .027) using the two-tailed Fisher exact test. [source] Development's invisible hands: Introduction to special issueJOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 6 2009Alan Thomas Abstract This Special Issue comes from the Development Studies Association (DSA) 30th Anniversary conference in 2008. The theme was ,Development's Invisible Hands', focusing on the forces likely to influence global change and re-shape development agendas over the next 30 years. The first section comprises brief invited thinkpieces mainly from DSA past presidents. Interestingly, while some focus on Adam Smith's original ,invisible hand' analogy and others discuss a range of non-market issues, several invoke Karl Polanyi on the limitations of market society. The second and third sections consist, respectively, of ,synthesis' papers on parallel panel themes and papers developed from the best panel presentations. The papers demonstrate the range of issues raised by questioning the future of development and development studies,while the limitations of future gazing are pointed up by the unexpected challenge to current development models presented since the conference by the global financial crisis. Copyright © 2009 John Wiley & Sons, Ltd. [source] A short history of the development studies associationJOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 6 2009Michael Tribe Abstract This paper outlines the origins of the Development Studies Association (DSA) in the 1960s together with the main features of the association since its formation in 1978. Some of the leading individuals in this evolution are identified, but it is made clear that institutional pressures have also been important over the years. Issues which threaten the Association include ,free-riding' (the obverse of which is ,externalities') as well as the linked question of those involved in ,development' who are neither members nor involved in the activities of the association. The paper also considers whether the DSA has ,made a difference', links the DSA to its European sister association, the European Association of Development Research and Training Institutes (EADI), and describes recent and prospective future developments. Copyright © 2009 John Wiley & Sons, Ltd. [source] Where we stand and what we stand for: The DSA now and in the futureJOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 6 2009Lalage Bown Abstract The paper looks at some visible and invisible challenges to development studies,seen as comprising a policy-related field,in relation to the UK and the DSA and against the background of world economic turmoil. They include: a revaluation of the multi-disciplinary and inter-disciplinary nature of the subject, to retain its broad base; the need to work within a comparative framework, linking poor and rich countries and the importance of a value base for development research. A strong appeal is made for better efforts to educate a wider public, especially in collaboration with the Development Education Association. Copyright © 2009 John Wiley & Sons, Ltd. [source] The private sector, poverty reduction and international developmentJOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 6 2007Chris Garforth Abstract The private sector, after shifting fortunes in development theory and practice over the years, is now widely recognised as the key to economic growth, which itself is indispensable for poverty reduction. The Development Studies Association (DSA) Annual Conference in 2006 brought together academics, private sector actors, NGOs and policy makers to share insights and experiences on how this vital contribution to growth, development and poverty reduction can be realised. This paper summarises the main themes and discussions of the conference and introduces the papers selected for inclusion in this conference issue. Copyright © 2007 John Wiley & Sons, Ltd. [source] Whole-body MR angiography using a novel 32-receiving-channel MR system with surface coil technology: First clinical experienceJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2005Michael Fenchel MD Abstract Purpose To demonstrate the feasibility of detecting atherosclerotic vascular disease using an innovative magnetic resonance angiography (MRA) protocol in combination with a dedicated whole-body MR scanner with new surface coil technology. Materials and Methods A total of 10 volunteers and eight patients with peripheral arterial occlusive disease (PAOD) were examined at 1.5 T. Conventional digital subtraction angiography (DSA) of the symptomatic region was available as a reference standard in all eight patients. Depending on subjects' size, four to five three-dimensional data sets were acquired using an adapted injection protocol. Images were assessed independently by two readers for vascular pathology. Additionally, signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were measured. Results Whole-body MRA yielded excellent sensitivity and specificity of more than 95% for both readers with high interobserver agreement (k = 0.93). Surface coil signal reception rendered a high SNR (mean 151.28 ± 54.04) and CNR (mean 120.75 ± 46.47). Despite lower SNR and CNR of the cranial and cervical vessels, a two-step injection protocol exhibited less venous superposition and therefore proved to be superior compared to single-bolus injection. Conclusion Our approach provides accurate noninvasive high-resolution imaging of systemic atherosclerotic disease, covering the arterial vasculature from intracranial arteries to distal runoff vessels. The recently introduced MR scanner and coil technology is feasible to significantly increase the performance of whole-body MRA. J. Magn. Reson. Imaging 2005;21:596,603. © 2005 Wiley-Liss, Inc. [source] Follow up of coiled intracranial aneurysms with standard resolution and higher resolution magnetic resonance angiographyJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 1 2008S Dupre Summary Time-of-flight magnetic resonance angiography is a non-invasive alternative to digital subtraction angiography (DSA) for follow up of coiled intracranial aneurysms. Standard cranial MRA protocols are a compromise between spatial resolution and imaging time. This study compares a standard resolution MRA protocol with a protocol at higher spatial resolution MRA (HR-MRA) in 21 follow-up occasions in 17 coiled aneurysms in 15 patients. Images were reviewed for presence of residual or recurrent aneurysm and compared with DSA as the gold standard. Aneurysm flow signal on standard resolution MRA differed significantly from HR-MRA in 6/21 cases (P = 0.02) and DSA in 6/21 cases (P = 0.02). HR-MRA had 100% concordance with DSA (P = 1.0). In this study, three-dimensional time-of-flight magnetic resonance angiography carried out at standard resolution is inadequate for follow up of coiled intracranial aneurysms. HR-MRA is comparable to DSA for detection of aneurysm recurrence. [source] Three-Dimensional Digital Subtraction Angiography in Evaluation of Vertebrobasilar Artery Dissections: Comparison with 2D DSAJOURNAL OF NEUROIMAGING, Issue 3 2010Ameer E. Hassan DO No abstract is available for this article. [source] Investigation of a New Approach to Measuring Contact Angles for Hydrophilic Impression MaterialsJOURNAL OF PROSTHODONTICS, Issue 2 2007Gerard Kugel DMD Purpose: The purpose of this investigation was to examine the initial water contact angles of seven unset impression materials using commercially available equipment, in an effort to determine whether polyether impression materials (Impregum) have lower contact angles and are, therefore, more hydrophilic than VPS impression materials. Materials and Methods: The hydrophilic properties of unset polyether and VPS impression materials were analyzed with respect to their water contact angle measurements using the commercially available Drop Shape Analysis System DSA 10. Twenty-five data points per second were collected via video analysis. There was no delay from start of measurement and data collection. Data was collected for approximately 12 s. Droplet size was determined on the thickness of canula. If the droplets became too small in volume, the water that evaporated during the measurement was large in comparison to the volume of the droplet. Therefore, 5 ,l was chosen as the lowest volume. Five trials were conducted per series for each featured material. Contact angles were calculated using the circle fitting method. Three tests using this technique were designed to control the variables of contact angle measurement with regard to time, the varying amount of fluid in contact with impression material during clinical use, and material thickness. Sample thickness of impression material was controlled by stripping the paste flat on a glass plate using a marking template to ensure a constant film thickness. Tests were conducted in a climatized room at 24°C ± 1°C. Deionized water was used as the fluid. The device was calibrated according to manufacturer's instruction for Young,Laplace fitting prior to the measurements. Results were analyzed using One-Way ANOVA, Tukey test, and t -test, as appropriate. Results: Comparing the fast setting impression materials by One-Way ANOVA and Tukey tests (p < .05) revealed the initial contact angles to range from 66.2 ± 1.5° to 127.5 ± 4.4°, of which the polyether material was the lowest after 45 s (66.2 ± 1.5°), 120 s (70.3 ± 2.8°), and 24 h (80.3 ± 1.0°) after start of the mix. The selected times represent the different stages of unset material, ranging from 45 s as the earliest practical data collection time to 24 h, at which a stone model would be poured. The polyether materials tested exhibited lower contact angles and, thus, significantly higher initial hydrophilicity than all measured VPS materials. Additionally, Impregum impression materials are more hydrophilic in the unset stage than in the set stage. VPS may show a stepwise development of hydrophilicity in the set stage that was not observed in the unset stage. Conclusions: The polyether impression materials tested were significantly more hydrophilic before, during, and after setting than that of VPS impression materials. Regardless of the amount of water in contact with the impression material, the polyether impression materials showed a significantly higher hydrophilicity in the unset stage than the VPS materials. The initial contact angle was not dependent on the thickness of the material. All parameters, including variation of time, volume of water droplet, and thickness of material, resulted in different absolute contact angles, but did not lead to a dramatic change in the ranking of the materials with regard to their hydrophilic behavior. [source] IV-DSA is a new diagnostic tool for axillary lymph node metastasis in breast cancer patientsJOURNAL OF SURGICAL ONCOLOGY, Issue 2 2004Osamu Watanabe MD Abstract Background and Objective The aim of this study is to know whether intravenous digital subtraction angiography (IV-DSA) is useful to detect axillary lymph node metastasis of breast cancer and to evaluate the anigiogenesis of lymph nodes in the axilla. Patients and Methods Forty three primary breast cancer patients (N0: 26 cases, N1: 5 cases, N2: 2 cases) who underwent IV-DSA between January and November 2000 were included in the study. Infinix CB apparatus (Toshiba, Japan) was used to collect IV-DSA images and when a mass became stained in the axilla, it was considered to be metastatic. The angiogenesis was studied by examining microvessel density (MVD) after lymph node immunostaining for factor VIII. Primary tumor was detected by IV-DSA in all 43 cases. Results Axillary lymph node metastases were detected by IV-DSA in 34.9% of cases (15/43), and by pathology in 37.2% (16/43). The sensitivity, specificity, and accuracy of the diagnostic method were 75.0% (12/16), 88.9% (24/27), and 83.7% (36/43), respectively. MVD, calculated after immunostaining for factor VIII, was significantly lower in the in metastatic region of lymph nodes identified by DSA (88.5,±,35.0) than in metastasis-free lymph nodes (141.1,±,34.0, P,<,0.0001). Conclusions IV-DSA is useful in the diagnosis of axillary lymph node metastasis of breast cancer. Our results suggest that the primary factors involved in the mechanism of DSA display may be different from high/low MVC values. J. Surg. Oncol. 2004;87:75,79. © 2004 Wiley-Liss, Inc. [source] Prevention of the Initiation of Atrial Fibrillation: Mechanism and Efficacy of Different Atrial Pacing ModesPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2000WEN-CHUNG YU Several atrial pacing modes have been reported to be effective in the prevention of atrial fibrillation (AF); they included biatrial pacing, dual site right atrial pacing, Bachmann's bundle (BB) pacing, and coronary sinus pacing. However, the relative efficacy and electrophysiological mechanisms of these pacing modes in the prevention of AF are not clear. In 15 patients (age 54 ± 14 years) with paroxysmal AF, P wave duration, effective refractory period, and atrial conduction time were determined with six different atrial drive pacings, that were right atrial appendage (RAA), BB, right posterior interatrial septum (RPS), distal coronary sinus (DCS), RAA plus RPS simultaneously (DSA), and RAA plus DCS simultaneously (BiA). All these patients consistently had AF induced with early RAA extrastimulation coupling to RAA drive pacing. No patient had AF induced with RAA extrastimulation coupled to BB, RPS, or DCS drive pacing, but seven and eight patients had AF induced with RAA extrastimulation coupled to DSA and BiA drive pacing, respectively. The P wave duration was longest during RAA pacing, and became shorter during other atrial pacing modes. Analysis of electrophysiological change showed that early RAA extrastimulation coupled to RAA drive pacing caused the longest atrial conduction delay among these atrial pacing modes; BB, RPS, and DCS drive pacing caused a greater reduction of this conduction delay than DSA and BiA drive pacing. In addition, the effective refractory periods of RAA determined with BB, RPS, and DCS drive pacing were similar and longer than that determined with DSA and BiA drive pacing. In patients with paroxysmal AF, this arrhythmia was readily induced with RAA extrastimuli coupled to RAA drive pacing. BB, RPS, and DCS pacing were similar and more effective than DSA and BiA pacing in preventing AF. [source] A Study of Ta Content Effect on Electro-Chemical Properties of Ir-Ta-O Coatings Deposited by Unbalanced Magnetron SputteringPLASMA PROCESSES AND POLYMERS, Issue S1 2007Sung Dae Kim Abstract In this study, Ir-Ta-O coating with various Ta contents in the range from 0 to 21.1 at.-% were synthesized by unbalanced magnetron sputtering (UBMS) method. The chemical concentration, crystalline structure, binding state, and morphology of coatings were characterized by electron probe microanalyzer (EPMA), X-ray photoelectron (XPS), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). In addition, the possibilities of Ir-Ta-O coatings synthesized by UMBS on a real dimensionally stable anode (DSA) electrode were investigated by electro-chemical application test. Ta existed mainly as a densely packed tantalum oxide compound in the Ir-Ta-O coatings and Ta oxidation states were changed from low oxidation state into high oxidation state in accordance with increase in Ta contents. The feasibility of making a DSA electrode prepared by physical vapor deposition (PVD) technique was demonstrated through the present work. [source] Comparing the dynamic behaviour of several rubbers filled with silanized silica nanofillerPOLYMER INTERNATIONAL, Issue 2 2009Saeed Ostad Movahed Abstract BACKGROUND: The effect of the same amount of precipitated silica nanofiller on the curing and dynamic properties of different rubbers, including natural rubber (NR) without and with the addition of elemental sulfur (NR with S), synthetic polyisoprene (IR), polybutadiene (BR) and poly(styrene- co -butadiene) copolymer (SBR), was investigated. The silica surfaces were pre-treated with bis(3-triethoxysilylpropyl)tetrasulfane (TESPT) to chemically bond the silica to the rubber. The rubbers were primarily cured by using sulfur in TESPT with the addition of optimum accelerator (TBBS) and activator (ZnO), which helped to form sulfur chemical bonds between the rubber and filler. RESULTS: Cure properties, Mooney viscosity, glass transition temperature, bound rubber and crosslink density along with dynamic properties of the filled rubbers, including tan ,, loss modulus (G,) and storage modulus (G,), were measured as a function of double oscillation amplitude (DSA) from 15 to 1000 µm, temperature from ,130 to 100 °C and frequency from 1 to 100 Hz. The results with emphasis on potential for tyre tread applications are discussed. It emerged that SBR along with BR filled rubbers had the highest rolling resistance while IR filled rubber had the least. Moreover, it was found that SBR filled rubber had the best skid resistance and BR filled rubber the worst. CONCLUSION: Interestingly, the variation of G, with DSA showed a complicated behaviour for different filled rubbers. It emerged that in some DSA ranges the Payne effect was observed, and in the remaining ranges increments of G, with DSA were seen. Because the bound rubber of most of the filled rubbers was more than 92%, there should be another predominant mechanism in the systems studied rather than simply de-agglomeration or filler network breakdown, which is proposed by the Payne model. In addition, the nanoscale of the filler may be effective for this behaviour. Copyright © 2008 Society of Chemical Industry [source] Peritransplant Immunoadsorption for Positive Crossmatch Deceased Donor Kidney TransplantationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 9 2010G. Bartel Various desensitization protocols were shown to enable successful living donor kidney transplantation across a positive complement-dependent cytotoxicity crossmatch (CDCXM). Positive crossmatch transplantation, however, is less well established for deceased donor transplantation. We report a cohort of 68 deceased donor renal allograft recipients who, on the basis of broad sensitization (lymphocytotoxic panel reactivity ,40%), were subjected to a protocol of peritransplant immunoadsorption (IA). Treatment consisted of a single session of immediate pretransplant IA (protein A) followed by posttransplant IA and antilymphocyte antibody therapy. Twenty-one patients had a positive CDCXM, which could be rendered negative by pretransplant apheresis. Solid phase HLA antibody detection revealed preformed donor-specific antibodies (DSA) in all 21 CDCXM-positive and in 30 CDCXM-negative recipients. At 5 years, overall graft survival, death-censored graft survival and patient survival were 63%, 76% and 87%, respectively, without any differences between CDCXM-positive, CDCXM-negative/DSA-positive and CDCXM-negative/DSA-negative recipients. Furthermore, groups did not differ regarding rates of antibody-mediated rejection (24% vs. 30% vs. 24%, p = 0.84), cellular rejection (14% vs. 23% vs. 18%, p = 0.7) or allograft function (median 5-year serum creatinine: 1.3 vs. 1.8 vs. 1.7 mg/dL, p = 0.62). Our results suggest that peritransplant IA is an effective strategy for rapid desensitization in deceased donor transplantation. [source] NK Cell Transcripts and NK Cells in Kidney Biopsies from Patients with Donor-Specific Antibodies: Evidence for NK Cell Involvement in Antibody-Mediated RejectionAMERICAN JOURNAL OF TRANSPLANTATION, Issue 8 2010L. G. Hidalgo To explore the mechanisms of antibody-mediated rejection (ABMR) in kidney transplants, we studied the transcripts expressed in clinically indicated biopsies from patients with donor-specific antibody (DSA). Comparison of biopsies from DSA-positive versus DSA-negative patients revealed 132 differentially expressed transcripts: all were associated with class II DSA but none with class I DSA. Many transcripts were expressed in DSA-positive ABMR but were also expressed in T-cell-mediated rejection (TCMR), reflecting shared molecular features. Removal of shared transcripts created 23 DSA selective transcripts (DSASTs). Some DSASTs (6/23) showed selective high expression in NK cells, whereas others (8/23) were expressed in endothelium or in endothelium plus other cell types (7/23). Of 145 biopsies ranked by DSAST expression, the 25 with highest DSAST expression primarily consisted of ABMR (22/25, 88%), either C4d-positive or C4d-negative. By immunostaining, CD56+ and CD68+ cells in peritubular capillaries, but not CD3+ cells, were increased in ABMR compared to TCMR, compatible with a role for NK cells, as well as macrophages, as effectors in endothelial injury during ABMR. Thus, the strategy of using DSASTs in the biopsy to identify mechanism-related transcripts in biopsies from patients with clinical phenotypes indicates the selective involvement of NK cells in ABMR. [source] Pancreas Allograft Biopsies with Positive C4d Staining and Anti-Donor Antibodies Related to Worse Outcome for PatientsAMERICAN JOURNAL OF TRANSPLANTATION, Issue 7 2010H. De Kort C4d+ antibody-mediated rejection following pancreas transplantation has not been well characterized. Therefore, we assessed the outcomes of 27 pancreas transplantation patients (28 biopsies), with both C4d staining and donor-specific antibodies (DSA) determined, from a cohort of 257 patients. The median follow-up was 50 (interquartile range [IQR] 8,118) months. Patients were categorized into 3 groups: group 1, patients with minimal or no C4d staining and no DSA (n = 13); group 2, patients with either DSA present but no C4d, diffuse C4d+ and no DSA or focal C4d+ and DSA (n = 6); group 3, patients with diffuse C4d+ staining and DSA (n = 9). Active septal inflammation, acinar inflammation and acinar cell injury/necrosis were significantly more abundant in group 3 than in group 2 (respective p-values: 0.009; 0.033; 0.025) and in group 1 (respective p-values: 0.034; 0.009; 0.002). The overall uncensored pancreas graft survival rate for groups 1, 2 and 3 were 53.3%, 66.7% and 34.6%, respectively (p = 0.044). In conclusion, recipients of pancreas transplants with no C4d or DSA had excellent long-term graft survival in comparison with patients with both C4d+ and DSA present. Hence, C4d should be used as an additional marker in combination with DSA in the evaluation of pancreas transplant biopsies. [source] Geographic Variation in End-Stage Renal Disease Incidence and Access to Deceased Donor Kidney TransplantationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 4p2 2010A. K. Mathur The effect of demand for kidney transplantation, measured by end-stage renal disease (ESRD) incidence, on access to transplantation is unknown. Using data from the U.S. Census Bureau, Centers for Medicare & Medicaid Services (CMS) and the Organ Procurement and Transplantation Network/Scientific Registry of Transplant Recipients (OPTN/SRTR) from 2000 to 2008, we performed donation service area (DSA) and patient-level regression analyses to assess the effect of ESRD incidence on access to the kidney waiting list and deceased donor kidney transplantation. In DSAs, ESRD incidence increased with greater density of high ESRD incidence racial groups (African Americans and Native Americans). Wait-list and transplant rates were relatively lower in high ESRD incidence DSAs, but wait-list rates were not drastically affected by ESRD incidence at the patient level. Compared to low ESRD areas, high ESRD areas were associated with lower adjusted transplant rates among all ESRD patients (RR 0.68, 95% CI 0.66,0.70). Patients living in medium and high ESRD areas had lower transplant rates from the waiting list compared to those in low ESRD areas (medium: RR 0.68, 95% CI 0.66,0.69; high: RR 0.63, 95% CI 0.61,0.65). Geographic variation in access to kidney transplant is in part mediated by local ESRD incidence, which has implications for allocation policy development. [source] Complement Independent Antibody-Mediated Endarteritis and Transplant Arteriopathy in MiceAMERICAN JOURNAL OF TRANSPLANTATION, Issue 3 2010T. Hirohashi Complement fixation, as evidenced by C4d in the microvasculature, is a widely accepted criterion of antibody-mediated rejection. Complement fixation has been shown to be essential in acute antibody-mediated rejection, but its role in chronic rejection has not been addressed. Previous studies showed that passive transfer of complement fixing monoclonal IgG2a anti-H-2Kk into B6.RAG1,/, KO recipients of B10.BR hearts led to progressive chronic transplant arteriopathy (CTA) over 14,28 days, accompanied by C4d deposition. The present studies were designed to test whether complement was required for these lesions. We report that a noncomplement fixing donor-specific alloantibody (DSA, monoclonal IgG1 anti-H-2Kk) injected into B6.RAG1 -/- KO recipients of B10.BR hearts also promotes CTA, without C4d deposition. Furthermore, a passive transfer of DSA (monoclonal IgG2a anti-H-2Kk) initiated endarteritis followed by CTA in B6.RAG1,/- mice genetically deficient in the third component of complement (RAG1,/,C3,/,). These studies indicate that antibody to class I MHC antigens can trigger chronic arterial lesions in vivo without complement participation, in contrast to acute antibody-mediated rejection. This pathway may be relevant to C4d-negative chronic rejection sometimes observed in patients with DSA, and argues that lack of C4d deposition does not exclude antibody-mediated chronic rejection. [source] Baseline Donor-Specific Antibody Levels and Outcomes in Positive Crossmatch Kidney TransplantationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 3 2010J. M. Gloor Renal transplant candidates with donor-specific alloantibody (DSA) have increased risk of antibody-mediated allograft injury. The goal of this study was to correlate the risk of antibody-mediated rejection (AMR), transplant glomerulopathy (TG) and graft survival with the baseline DSA level (prior to initiation of pretransplant conditioning). These analyses include 119 positive crossmatch (+XM) compared to 70 negative crossmatch (,XM) transplants performed between April 2000 and July 2007. Using a combination of cell-based crossmatch tests, DSA level was stratified into very high +XM, high +XM, low +XM and ,XM groups. In +XM transplants, increasing DSA level was associated with increased risk for AMR (HR = 1.76 [1.51, 2.07], p = 0.0001) but not TG (p = 0.18). We found an increased risk for both early and late allograft loss associated with very high DSA (HR = 7.71 [2.95, 20.1], p = 0.0001). Although lower DSA recipients commonly developed AMR and TG, allograft survival was similar to that of ,XM patients (p = 0.31). We conclude that the baseline DSA level correlates with risk of early and late alloantibody-mediated allograft injury. With current protocols, very high baseline DSA patients have high rates of AMR and poor long-term allograft survival highlighting the need for improved therapy for these candidates. [source] Bortezomib as the Sole Post-Renal Transplantation Desensitization Agent Does Not Decrease Donor-Specific Anti-HLA AntibodiesAMERICAN JOURNAL OF TRANSPLANTATION, Issue 3 2010R. Sberro-Soussan Persistence of donor-specific anti-HLA antibodies (DSA) associated with antibody-mediated graft injuries following kidney transplantation predicts evolution toward chronic humoral rejection and reduced graft survival. Targeting plasma cells, the main antibody-producing cells, with the proteasome inhibitor bortezomib may be a promising desensitization strategy. We evaluated the in vivo efficacy of one cycle of bortezomib (1.3 mg/m2× 4 doses), used as the sole desensitization therapy, in four renal transplant recipients experiencing subacute antibody-mediated rejection with persisting DSA (>2000 [Mean Fluorescence Intensity] MFI). Bortezomib treatment did not significantly decrease DSA MFI within the 150-day posttreatment period in any patient. In addition, antivirus (HBV, VZV and HSV) antibody levels remained stable following treatment suggesting a lack of efficacy on long-lived plasma cells. In conclusion, one cycle of bortezomib alone does not decrease DSA levels in sensitized kidney transplant recipients in the time period studied. These results underscore the need to evaluate this new desensitization agent properly in prospective, randomized and well-controlled studies. [source] Cluster Analysis of Lesions in Nonselected Kidney Transplant Biopsies: Microcirculation Changes, Tubulointerstitial Inflammation and ScarringAMERICAN JOURNAL OF TRANSPLANTATION, Issue 2 2010B. Sis Banff classification empirically established scoring of histologic lesions, but the relationships of lesions to each other and to underlying biologic processes remain unclear. We hypothesized that class discovery tools would reveal new relationships between individual lesions, and relate lesions to C4d staining, anti-HLA donor-specific antibody (DSA) and time posttransplant. We studied 234 nonselected renal allograft biopsies for clinical indications from 173 patients. Silhouette plotting and principal component analysis revealed three groups of lesions: microcirculation changes, including inflammation (glomerulitis, capillaritis) and deterioration (double contours, mesangial expansion); scarring/hyalinosis; and tubulointerstitial inflammation. DSA and C4d grouped with microcirculation inflammation, whereas time posttransplant grouped with scarring/hyalinosis lesions. Intimal arteritis clustered with DSA, C4d and microcirculation inflammation, but also showed correlations with tubulitis. Fibrous intimal thickening in arteries clustered with scarring/hyalinosis. Capillary basement membrane multilayering showed intermediary relationships between microcirculation deterioration and time-dependent scarring. Correlation analysis and hierarchical clustering confirmed the lesion relationships. Thus, we propose that the pathologic lesions in biopsies are not independent but are members of groups that represent distinct pathogenic forces: microcirculation changes, reflecting the stress of DSA; scarring, hyalinosis and arterial fibrosis, reflecting the cumulative burden of injury over time; and tubulointerstitial inflammation. Interpretation of lesions should reflect these associations. [source] The Impact of C4d Pattern and Donor-Specific Antibody on Graft Survival in Recipients Requiring Indication Renal Allograft BiopsyAMERICAN JOURNAL OF TRANSPLANTATION, Issue 12 2009A. Haririan We examined the pattern of PTC C4d by immunohistochemistry and DSA in 297 kidney recipients with indication biopsies, and evaluated their predictive value for graft survival. Median biopsy time was 5.1 months posttransplant. Patients were followed for 17.9 ± 9.4 months postbiopsy. An 18.5% had focal and 15.2% had diffuse C4d, with comparable graft survival (adjusted graft failure HR: 2.3, p = 0.001; HR:1.9, p < 0.02, respectively). 31.3% were DSA+, 19.5% class I and 22.9% class II DSA. Only those with class II DSA had worse outcome (adjusted HR:2.5, p = 0.001 for class II only; HR:2.7, p < 0.001 for class I/II DSA). Among patients with <10%C4d, 23.9% had DSA, compared to 68.9% with diffuse staining. For patients biopsied in first-year posttransplant presence of DSA, regardless of C4d positivity in biopsy, was a poor prognostic factor (adjusted graft failure HR: 4.2, p < 0.02 for C4d,/DSA+; HR:4.9, p = 0.001 for C4d+/DSA+), unlike those biopsied later. We have shown that focal C4d had similar impact on graft survival as diffuse pattern. During the first-year posttransplant either class I or II DSA, and afterward only class II DSA were associated with worse graft survival. DSA was predictive of worse outcome regardless of C4d for patients biopsied in first year and only with C4d positivity afterward, supporting the importance of assessment of both DSA and C4d pattern in biopsy. [source] | ||||||||||||||||||||||||||||||||||